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Grundfos Challenge: Design and integration of a gear unit for a hydronic valve into an enclosure box

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Pumps and valves are vital components in any hydronic system and their performance can make a huge difference on the overall system performance. An essential part of valves performance is their ability to always position the valve seat correctly. Several contradictive parameters are involved in such positioning systems by which an optimal solution is achieved through best compromise. The Grundfos Challenge is therefore to provide solutions for design and integration of a gear unit for a hydronic control valve.

The Challenge
The Challenge is design and development of a gear unit for a hydronic valve that is thoroughly integrated into an enclosure box. Thus, we seek the best solution to the challenge: How can a gear drive train system, that meets certain gear box requirements, be designed, while ensuring a thorough integration of the system into the enclosure box to accommodate the structural integrity of the product? (See figures and attached CAD drawings). The solution is bounded by the technical requirements to the enclosure box, design-space envelope and gearbox (shaft output torque etc.) specified below

Requirements

  • Technical Requirements (See details in Case Documentation)


    Enclosure box (red in attached figures)
    • The enclosure box is sealed by a lid (not shown). The lid should not be designed nor be considered with respect to the structural integrity
    • Outer surfaces of the enclosure box cannot be changed
    • Inner surfaces of the enclosure box may be changed to form the interface to the gear system e.g. adding towers, pins, etc. to transfer loads to the box
    • All forces from the gear train are transferred via the box
    • All degrees of freedom are fixed at the end of the cylindrical face (blue circle in attached figures)
    • Manufacturing: Injection molding, tool disassembly direction, Z.
    • Min. material thickness: 1mm
    • Material: Polycarbonate 10% glass fiber – Assume linear material properties (23 degrees Celsius): E=4.114GPa, ν=0.38, ρ=1270kg/m3
    • Assembly: Gear unit is mounted in the enclosure in the Z-direction


    Design-space envelope
    • The gear drive train system must fit within the specified design-space envelope of the enclosure box (black/grey box – see figures and attached CAD drawings).
    • The motor must also fit within the design-space envelope.


    Gear system
    • Free choice of gear system e.g. planetary, worm, spur etc.
    • Minimal maintenance systems are preferred
    Electric motor
    • The motor for the gear system is pre-specified and provides a well-defined input torque: See attached motor pull out torque curve (clockwise and counter-clockwise)
    • Allowable RPM range: 500-1500RPM
    • Dimension: See attached CAD file
    • Shaft connection: Flat shaft
    • Operation mode: 3 sec ON followed by 7 sec OFF

    Output shaft
    • RPM: 1 RPM +/- 5%
    • Torque: 20Nm +/- 1Nm (at 1 RPM)
    • Radial rotating force: Maximum 300N at tip
    • Movement: Bi-directional (open/close of valve) – 360 degrees in both directions (no fixed stop)
    • Hysteresis: < 3 degrees
    • Material: Steel – E=200GPa, ν=0.3, ρ=7800kg/m3
    • Shaft Connection: Oldham

  • Judging criteria

    1. Are the technical requirements met?
    • Within the design-space envelope?
    • Is assembly in Z-direction possible?
    • Etc.

    2. Is the solution considered reliable and robust?

    3. Is the gear principle novel and maintenance-free?

    4. Designs with the following features are favored:
    • Non-lubricated gear systems
    • The compactness of solution (considering potential thermal risks for gear unit and PCBs in enclosure box)
    • Low weight
    • Low cost
    • Low hysteresis on the output shaft

    5. Alternative and creative features to improve the product and/or its application further e.g. out-of-spec. application, added value, improved robustness, manufacturing, high lifetime, maintenance-free, etc.

  • Submission

    • Submit CAD files in STEP format
    • Screenshots in various views (preferably rendered)
    • Screenshots of simulation results (if applicable) and a small description of the setup (so that it can be replicated by the jury)
    • Documentation incl.
    - Gear ratio
    - Bill of material incl. material composition
    - Design considerations e.g. on manufacturing, assembly, reliability etc.
    - Description of alternative/creative features
    - Etc.

  • *DOWNLOAD IMPORTANT FILES BELOW*

    Be sure to use the Specification Download button below to Download the Case Documentation, Pictures and CAD Files for this Challenge (The CAD Files are Required for this Challenge!)

Download specification

Rules

  • ENTERING THE COMPETITION:


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      GRUNDFOS CHALLENGE SPECIFIC ENTRY AGREEMENT:
      By submitting an Entry in the Grundfos Challenge, each Top 3 Finalists grants to Grundfos (Sponsor) and its designees a worldwide, non-exclusive, sub-licensable, transferable, fully paid up, royalty-free, perpetual, irrevocable right to use, reproduce, distribute, create derivative works from, publically perform, publically display, digitally perform, make, have made, sell, offer for Sale and import the Entry and to develop or have developed the technology described in the Entry, in any media now known or hereafter developed for any purpose whatsoever, commercial or otherwise, without further approval by Entrant (“Non-Exclusive License”).

      If Entrant’s Entry is awarded a prize in the Grundfos Challenge, Entrant agrees to and does hereby grant to Sponsor and its designees a worldwide, exclusive, sub-licensable, transferable, fully paid up, royalty-free, perpetual, irrevocable right to use, reproduce, distribute, create derivative works from, publically perform, publically display, digitally perform, make, have made, sell, offer for Sale and import the Entry and to develop or have developed the technology described in the Entry, in any media now known or hereafter developed for any purpose whatsoever, commercial or otherwise, without further approval by Entrant (“Exclusive License”).

      By submitting an Entry, Entrant represents that is has the right to grant these rights and the Exclusive License.

  • SUBMITTING AN ENTRY


    Only entries uploaded to GrabCAD through the "Submit entry" button on this Challenge page will be considered an entry. Only public entries are eligible. We encourage teams to use GrabCAD Workbench for developing their entries. Entries are automatically given the tag "GrundfosChallenge2019" when uploading to GrabCAD. Please do not edit or delete this tag. Only entries with valid tag will participate in the Challenge.

  • AWARDING THE WINNERS


    The sum of the Awards is the total gross amount of the reward. The awarded participant is solely liable for the payment of all taxes, duties and other similar measures if imposed on the reward pursuant to the legislation of the country of his/her residence, domicile, citizenship, workplace, or any other criterion of similar nature. Only 1 award per person. Prizes may not be transferred or exchanged. All winners will be contacted by the GrabCAD staff to get their contact information and any other information needed to get the prize to them. Payment of cash awards is made through PayPal. All team awards will be transferred to the member who entered the Challenge.

  • We will release the finalists before the announcement of the winners to give the Community an opportunity to share their favorites in the comments, discuss concerns, and allow time for any testing or analysis by the Jury. The Jury will take the feedback into consideration when picking the winners.


    Winning designs will be chosen based on the Rules and Requirements.

  • Schedule


    This Challenge ends on November 19th, 2019 (23:59 EST.) Finalists will be announced on November 26th, 2019. Winners will be announced on December 3rd, 2019.

Prizes

Prizes

$10000 in Prizes

1st Place

$6000

2nd Place

$3000

3rd Place

$1000

*IMPORTANT*
All prizes will be awarded through Paypal. Please make sure that you have a Paypal account ready beforehand when we start awarding prizes to get your winnings quicker. We will NOT use any other payment method to award your winnings.

About Grundfos

Grundfos is a global leader within advanced pump solutions employing more than 19,000 employees in 56 countries worldwide. Our purpose is to pioneer solutions to the world’s water and climate challenges and improve quality of life for people.
We dare to do things that others do not in order to overcome the complex challenge of moving water in the most intelligent and energy efficient way. We believe that innovation is not only a business opportunity, but an obligation. And what really matters to us is not short-term profit, but the impact we make. We have the determination and power to set the standard for the industry and society as a whole. We are not only pioneers. We are also game changers.

For more information, visit our company website at www.grundfos.com.

212 comments

  • SWARAJ BISWAS

    SWARAJ BISWAS 3 months ago

    Please specify the following: 1. What will be the operating speed of the motor. 2. If there is no operating speed, then please specify the top speed of the motor.

    SWARAJ BISWAS has uploaded 30 CAD models & has left 28 comments.
  • Chris Tziros

    Chris Tziros 3 months ago

    Under the section called "Gear Unit" you have specified the material properties by writting "Material: Steel – E=200GPa, ν=0.3, ρ=7800kg/m3".
    Is this a restriction only for out gear unit casing?
    Our we allowed to use deferent materials on the gears themselves?
    Also what is happening on the side of the red-Enclosure box that is not beeing shown? Should we design it, Is it going to be open to the enviroment (air/water), is it going to be sealed, or should we just leave that out of our design considerations?

    Chris Tziros has uploaded 19 CAD models & has left 70 comments.
  • neomechanikos

    neomechanikos 3 months ago

    Questions:
    1. What is the total rotational distance required to actuate the valve?
    2. Is it correct to assume the Z direction is indicated by the blue arrow?
    3. Please explain "no fixed gear principle" in the gear system requirements. Should this be interpreted that there are no specific gear requirements?
    4. What is the method of transferring the motor torque to the gearbox and to the valve? Such as keyed shaft, shaft flat, spline, force fit, etc.
    Thank you.

    neomechanikos has uploaded 0 CAD models & has left 2 comments.
  • Lasse Ledet

    Lasse Ledet 3 months ago

    Hi all,

    Thanks for your questions. We will update the requirements with your inputs ASAP, but for consistency here are the answers to your inquiries:

    SWARAJ BISWAS: There is no fixed RPM requirements for the motor, however, the allowable RPM range is specified to 500-1500RPM

    Chris Tziros: It is only the output shaft where steel is required. For the remaining gear system, it is entirely up to you – even for the gear unit casing. Regarding the enclosure box: It is sealed by a lid (not shown), which need not be designed nor a part of the design considerations. Similarly, the structural integrity should be preserved also without considering the lid

    neomechanikos: 1) The total rotational distance is 360 degrees in both directions with no fixed stop (because the enclosure box may be oriented in several ways with respect to the valve seat. 2) Yes, this is correct, thanks for pointing it out. 3) There are no requirements to which gear technology you decide to use e.g. it may be planetary, worm, spur gears etc. 4) The connection between the motor and gearbox is with a flat shaft connection and between the output shaft and valve an Oldham connection (however this connection may be neglected).

    I hope this answers your inquiries, otherwise feel free to comment again

    /Lasse

    Lasse Ledet has uploaded 0 CAD models & has left 15 comments.
  • Kesa

    Kesa 3 months ago

    There is an Update in the Specifications download. Please download the new Version if you havent already.

    Kesa has uploaded 1 CAD models & has left 81 comments.
  • Lukasz

    Lukasz 3 months ago

    After downloading the specification, there are no CAD files

    Lukasz has uploaded 1 CAD models & has left 1 comments.
  • Ben Casto

    Ben Casto 3 months ago

    Are the final output figures quoted as if the motor was running constantly or do these include the 7 second off time?

    Ben Casto has uploaded 13 CAD models & has left 53 comments.
  • Kesa

    Kesa 3 months ago

    The new Specification Should have the files in there now. Thank you Lukasz

    Kesa has uploaded 1 CAD models & has left 81 comments.
  • Thomas Sutrina

    Thomas Sutrina 3 months ago

    The gear ratio is large. The likelihood that any type of gear train can be back driven is small. The torque electrical connection is not presented and the torque curve is typical of a PM motor or a stepper motor. Your graph does not present the toque at zero RPM Which suggest that the motor is not design to operate to hold position. So is a requirement that the gear train can not be back driven?

    Thomas Sutrina has uploaded 3 CAD models & has left 34 comments.
  • Thomas Sutrina

    Thomas Sutrina 3 months ago

    Please elaborate, "Torque: Maximum 16Nm at 1 RPM and Radial rotating force: Maximum 300N at tip." Is the maximum torque created by the maximum force as some lever length? Does the housing of the gearbox we are responsible for required to take the 300 N maximum force? and if so what is the lever length along the Z axis. Otherwise I would assume that your enclosure or the valve body handles the forces generated by the fluid and the closure contact forces except for a pure torque, 16 Nm. What is the torque at closure; zero RPM? Obviously this is the actual final condition the motor must drive the valve up to. Also what is the hysteresis to initiate motion, zero to 1 RPM?

    Thomas Sutrina has uploaded 3 CAD models & has left 34 comments.
  • Thomas Sutrina

    Thomas Sutrina 3 months ago

    No position senors are required, however; some means of determining the closure of the valve is needed. This could be mechanical stops in the valve and once the torque exceeds a value which has a matching current your controller turns it off. Two position valve. For a position-able valve you may have sensors elsewhere. Other approaches such as time and angle or turns count of the motor would do the same thing from the two stops. I do not know the details but the choice of drives would be effected.

    Thomas Sutrina has uploaded 3 CAD models & has left 34 comments.
  • Brandon McLaughlin

    Brandon McLaughlin 3 months ago

    There is a typo somewhere in the description... the output torque says 20Nm in the pdf file I downloaded. However it says 16Nm in the above description. Which is it? 4Nm is a significant amount of torque.

    Also, it is impossible to meet the power requirements as listed. To move the output shaft 360 degrees in 3 seconds, you would require 16Nm x 2pi radians / 3 seconds. This is 335 watts.

    The motor provided can only deliver 1/10th this amount. For example, at 800 RPM, the curve shows 40mNm, giving a maximum power of 3.35 watts. I'm hoping that the valve actuator (output) shaft has 10 times the amount of torque listed, or that the time requirement is 30 seconds instead of 3.

    Can someone please clarify this? It impacts my design.

    Brandon McLaughlin has uploaded 0 CAD models & has left 10 comments.
  • Brandon McLaughlin

    Brandon McLaughlin 3 months ago

    I'm sorry, the output would be 33.5 watts in the above comment ^^^, I guess we are all liable to have typos :)

    Brandon McLaughlin has uploaded 0 CAD models & has left 10 comments.
  • Nic

    Nic 3 months ago

    In regards to the motor, should the electrical connector be flush with the external envelope to allow for direct connection, or, should the cabling be passed via a grommet of some type? Is the motor hard-wired with no pluggable connection?

    Nic has uploaded 26 CAD models & has left 89 comments.
  • Chris Tziros

    Chris Tziros 3 months ago

    So, what is the output torque at 1 rpm, 16 or 20 Nm?

    Chris Tziros has uploaded 19 CAD models & has left 70 comments.
  • Brandon McLaughlin

    Brandon McLaughlin 3 months ago

    Chris Tziros, I'm going to roll with 1.6Nm until I am told otherwise for the power reasons stated above. That's a 10 times difference in output torque, but it's either that or they let us take longer to do the move.

    Brandon McLaughlin has uploaded 0 CAD models & has left 10 comments.
  • geo

    geo 3 months ago

    @ Grundfos: To have a better final solution, a feedback for All is helpful. Evaluation example: Function = 2 points, manufacturability = 9 points, number of parts / costs = 10 points. Result = 7.0 points. A gear ratio 1:85 is mandatory.
    I am of the opinion, that Courtesy in the wrong place does not produce a good construction.

    geo has uploaded 20 CAD models & has left 677 comments.
  • Sava Savov

    Sava Savov 3 months ago

    Brandon, I think you don't have to "... move the output shaft 360 degrees in 3 seconds...". The output speed must be 1 rpm, as far as I can see. So if output torque is 16 Nm you get for the output power: P=16Nm x 2pi radians / 60 seconds = 1,676 W. I think that the problem will be the input power because it depends on mechanism - how much will be the mechanism resistance (how much power will be needed to overcome this resistance before we can get the final output power).

    Sava Savov has uploaded 18 CAD models & has left 114 comments.
  • Brandon McLaughlin

    Brandon McLaughlin 3 months ago

    Sava, I am totally good with that understanding. I guess the "on time 3 seconds, off time 7 seconds" can be thrown in the trash can and we stick with the 1 RPM as a fixed output speed and the 1.676 W is the power output required, which is theoretically possible to accomplish with the approximately 3.35 W max output on the dinky little motor. Thanks for the comment!

    Brandon McLaughlin has uploaded 0 CAD models & has left 10 comments.
  • Brandon McLaughlin

    Brandon McLaughlin 3 months ago

    And yes, the mechanism efficiency would have to be no worse than 50%. This is the challenge. Let's see what we can do!

    Brandon McLaughlin has uploaded 0 CAD models & has left 10 comments.
  • Thomas Sutrina

    Thomas Sutrina 3 months ago

    This is a small valve so my guess is that the traveling torque could be 1/10 or less of the value to setting or breaking the sealing of the valve. However that also requires the zero RPM torque point of the motor. Generally the pressure drop across the valve times the area of the closure and time the drag coefficient for rotation is small until almost full closure is approached. The only exception is for a butterfly valve that is only used for large valves.

    Thomas Sutrina has uploaded 3 CAD models & has left 34 comments.
  • Brandon McLaughlin

    Brandon McLaughlin 3 months ago

    I was curious about the type of valve as well.... I have a few ideas about mechanisms that would not give constant torque through the full move, but they would maintain on average >16Nm. It's kind of a moot point though since they don't specify the resistant torque profile through the move.

    Brandon McLaughlin has uploaded 0 CAD models & has left 10 comments.
  • Sava Savov

    Sava Savov 3 months ago

    Maximum torque is 16 Nm (or 20 Nm) but is there a minimum torque that can be acceptable for valve to work properly?

    Sava Savov has uploaded 18 CAD models & has left 114 comments.
  • Brandon McLaughlin

    Brandon McLaughlin 3 months ago

    If the requirement was constant torque, constant speed, then the list of available approaches to the design is somewhat limited. If we are allowed some wiggle room, for example a sinusoidal, cycloidal, or other type of curve on the angular velocity of the output shaft, then we have a few other options on the table. Since it is a valve and as Thomas pointed out there are places where you won't see a whole lot of resistance, some of these approaches can be "clocked" so that the high points on the output torque curve would align with the points of high resistance. And who really cares what the angular velocity profile of a closing valve at 1 rpm really is? It's slow as all hell.

    Brandon McLaughlin has uploaded 0 CAD models & has left 10 comments.
  • Lasse Ledet

    Lasse Ledet 3 months ago

    Hi all,

    Thanks for all the great comments. We are very glad to see passionate people that are keen to solve a problem that is not so easy. I’ll try to answer your questions below.

    First, sorry for the confusion about the torque level. The correct specifications are: 20Nm +/- 1Nm (as in the attachments). We will correct this ASAP.

    Besides the torque, the output shaft must also withstand the radial force (simultaneously). It is placed at the tip of the shaft (length available from the CAD files) and the force does not produce any additional torque.

    The torque is generated by the resistance of the valve seat and the valve seat itself will ensure that the system is self-contained from hydraulic forces.

    The valve position is feedback controlled by sensors placed in the fluid and its strict position is therefore not important. However, too much hysteresis disrupts stable feedback control.

    The attached motor curve is a test curve for the motor as standalone and not a measurement from operation of the actual system. Extrapolating the motor curve will give you the torque a zero RPM.

    The start torque on the output shaft is included in the torque specifications. The controller handles changing torque e.g. from stationary to moving valve seat.

    The output shaft moves at 1RPM (+/-5%) with an operation cycle of 3 sec. ON followed by 7 sec. OFF. This means that the valve is not able to close in one go. The operation cycle relates to the gear unit’s durability, if designers wish to consider this.

    The motor is a step motor connected by four wires. The wires are connected to a PCB inside the enclosure.

    @geo we agree that a weighting system would generally be convenient, however, as these alternative/creative features are indeed secondary requirements we feel a weighting system is not suitable.

    I hope this answers all your questions otherwise feel free to comment again.

    Lasse Ledet has uploaded 0 CAD models & has left 15 comments.
  • Brandon McLaughlin

    Brandon McLaughlin 3 months ago

    Thanks. It clarifies a few things. I think some people are interested in the work required to close the valve into its seat. Let's define 0 degrees as the fully closed state and 360 degrees as the fully opened state. It could be that as we are closing the valve, most of the travel should be of relatively low resistance until some specified angle, that at which the valve seat is interacting with the valve.

    Maybe it's that the valve seat is resisting the 20Nm +/- 1Nm for the entire stroke. That's a lot of work for this little motor to do. But maybe it's only resisting at say that last 45 degrees before valve closed. There is a large difference in the work required here. 8 times more, in fact.

    This is important to know because then the mechanism can be designed to concentrate it's efforts into that last bit of travel. For example you could have the system move quickly through most of the stroke and then spend a lot more time on the portion of high resistance. Otherwise you're just wasting time. Does this make sense?

    Brandon McLaughlin has uploaded 0 CAD models & has left 10 comments.
  • manish shah

    manish shah 3 months ago

    Can anyone explain what the fixed gear principle is ?

    manish shah has uploaded 26 CAD models & has left 59 comments.
  • Lasse Ledet

    Lasse Ledet 3 months ago

    @Brandon: It certainly makes sense and you are absolutely right that the torque on the valve is generally not constant throughout its stroke. However, as the valve may be in the same position for long enough that it can get stuck, we need the 20Nm to make sure we can loosen it again. And unfortunately, this can happen at arbitrary positions.

    @Manish what is meant by “No fixed gear principle” simply means that you may choose whichever gear mechanism you find suitable e.g. spur, worm, mesh etc.

    Lasse Ledet has uploaded 0 CAD models & has left 15 comments.
  • Brandon McLaughlin

    Brandon McLaughlin 3 months ago

    Ok, that's reasonable for now. Thanks!

    Brandon McLaughlin has uploaded 0 CAD models & has left 10 comments.
  • Thomas Sutrina

    Thomas Sutrina 3 months ago

    The step model of the stepper motor does not have a 'D' shape but is round. Your words tell us it is a shaft with a flat. I assume the the step files in the two folders are identical.

    Manish Shah. Fixed gears on a car with a manual transmission means that first gear is a fix ratio. Second is a fix ratio etc. The ratio for a two pulley belt drive is fixed so long as slippage is very small. And induction motor is considered a fixed speed motor because at the design torque the speed is fixed, what is listed for the motor as you know the speed when sold are listed with a few steps.

    Thomas Sutrina has uploaded 3 CAD models & has left 34 comments.
  • Thomas Sutrina

    Thomas Sutrina 3 months ago

    It appears that the motor is an TSM49-075 from Anaheim Automation which doesn't have a flat on their base line unit.

    Thomas Sutrina has uploaded 3 CAD models & has left 34 comments.
  • Thomas Sutrina

    Thomas Sutrina 3 months ago

    I think we can assume the flat is 1 mm off from the center of the shaft which seems like a standard.

    Thomas Sutrina has uploaded 3 CAD models & has left 34 comments.
  • Sava Savov

    Sava Savov 3 months ago

    Is there a problem if the torque is 2-3 times larger than 20 Nm just in beginning of the motion, just to peel off, and then to decrease to 20 Nm until the angular velocity reaches 1rpm? Or it is dangerous the torque to be so high so as to not overload something?

    Sava Savov has uploaded 18 CAD models & has left 114 comments.
  • Sava Savov

    Sava Savov 3 months ago

    After all, why not show the whole valve - no one will steal it, but even if it does, everything is documented here.

    Sava Savov has uploaded 18 CAD models & has left 114 comments.
  • André Succissi Rinaldi

    André Succissi Rinaldi 3 months ago

    A question that came to my mind on the engine torque chart.
    In the torque axis there is the dimensional mNm, would this dimensional correspond to Nmm or only Nm?

    André Succissi Rinaldi has uploaded 2 CAD models & has left 4 comments.
  • Ananth Narayan

    Ananth Narayan 3 months ago

    @André Succissi Rinaldi, it's mill Newton-meter.

    Ananth Narayan has uploaded 63 CAD models & has left 280 comments.
  • Lasse Ledet

    Lasse Ledet 3 months ago

    @Thomas: Yes, the shaft is just round in the CAD file and you may consider it round or with a D-shape in your design. It will not affect the judgement of your entry :-)

    @Sava: As we are using a step motor you may consider the 20Nm as a maximum since the torque of the motor is proportional to the ampere input. This means that the controller can decrease the torque if needed whereas an increase (above 20Nm) will be damaging for the structure. To not constrain the design of the gear system unnecessarily we have chosen to not disclose the valve.

    @André: It is correct that mNm refers to milli-Newton meter

    Lasse Ledet has uploaded 0 CAD models & has left 15 comments.
  • Melville

    Melville 3 months ago

    Hi
    I can now grasp the gravity of problem !!
    Gone through the initial stages of gear selection !!
    With the commercial "rigid" drives out there can be a big issue
    I presume that the output required is precise that is 1 rpm with "small" change
    I understand that a range of inputs are given such as 500-1500 RPM
    If we use a gear the ratio is very rigid and the output will be dangerously low
    I think that the solution would be near pure electronic with German VFD

    Melville has uploaded 12 CAD models & has left 8 comments.
  • Sava Savov

    Sava Savov 3 months ago

    A planetary gearbox can solve the problem easy ! But I tried something else and it seems it will work - never saw this before and i will bet on it.

    Sava Savov has uploaded 18 CAD models & has left 114 comments.
  • Thomas Sutrina

    Thomas Sutrina 3 months ago

    "D" flat on the motor output shaft does effect the design. Without a flat then creep on the mate is low enough that friction works via shrink fit or a screw.

    I do agree that for evaluation it doesn't matter since your engineers will fix the problem.

    Thomas Sutrina has uploaded 3 CAD models & has left 34 comments.
  • Chris Tziros

    Chris Tziros 3 months ago

    @Sava Savov,
    what would be the angular backlash of the planetery gearbox though?

    Chris Tziros has uploaded 19 CAD models & has left 70 comments.
  • Sava Savov

    Sava Savov 3 months ago

    I can't translate to myself what exactly backlash means. Maybe if only planetary gearbox is used, the motor must have a brake integrated.

    Sava Savov has uploaded 18 CAD models & has left 114 comments.
  • Halbmond

    Halbmond 3 months ago

    Read all the comments. So the ratio is 500:1 ? Input speed may change 500 to 1500 rpm and output speed 1 to 3 rpm ?

    Halbmond has uploaded 0 CAD models & has left 18 comments.
  • Sava Savov

    Sava Savov 3 months ago

    @Halbmond,
    The nominal output speed is 1 rpm. If you choose the nominal speed of the motor to be 1000 rpm (for example), you have to make a gear box with ratio=1000/1. I thing so.

    Sava Savov has uploaded 18 CAD models & has left 114 comments.
  • Daniel Gelep

    Daniel Gelep 3 months ago

    Damn, I see a lot of comments and I really do not understand what is unclear for you guys ? Input data, output data and requirements are extremely clear. I understand all from one reading without any other question. Is not missing any other info or shall not be need any extra clarification.

    I also start to work on this and I will present at the proper time.

    Good luck to all of you.

    Daniel Gelep has uploaded 0 CAD models & has left 4 comments.
  • Melville

    Melville 3 months ago

    Hi for gearbox planetary number of teeth use "http://www.mekacademy.com/
    for teeth selection !

    Melville has uploaded 12 CAD models & has left 8 comments.
  • Nic

    Nic 3 months ago

    Can we please be given some indication of the intended/prospective production volume for this unit? It would help to inform the choice between off-the-shelf and custom components. Thanks

    Nic has uploaded 26 CAD models & has left 89 comments.
  • Ankush Sharma

    Ankush Sharma 3 months ago

    i am unable to understand 1 thing. we need 1rpm at the output shaft as well as 20Nm torque as well, how can we reduce both torque and rpm at the same time?

    Ankush Sharma has uploaded 1 CAD models & has left 1 comments.
  • Ananth Narayan

    Ananth Narayan 3 months ago

    @Ankush Sharma, please see the documentation pull out graph it's milli-newton-meter. Hope you might have misunderstood. Reduce the speed by increasing torque.

    Ananth Narayan has uploaded 63 CAD models & has left 280 comments.
  • df

    df 3 months ago

    This job to done properly require quite a lot of work. Most probably few months for first the successful iteration, then later do it 2 more times to get it really right. And also quite a lot of testing to get materials right, to get tolerances right and to satisfy all this criteria (which cost quite a lot). I did design for similar project so remember problems. Also, to get `some indication about position` you need to design PCB with electrical schematics, including motor controls and do some software to see if idea works. Good luck with 10 000 usd budget :)

    df has uploaded 1 CAD models & has left 3 comments.
  • Lasse Ledet

    Lasse Ledet 3 months ago

    @Nic you may assume high volume production

    Lasse Ledet has uploaded 0 CAD models & has left 15 comments.
  • Elie VILLAIN

    Elie VILLAIN 3 months ago

    Hello,
    I have a question about "min material thickness: 1mm"
    Does this also affect the width of the teeth of the gear ?

    Elie VILLAIN has uploaded 3 CAD models & has left 32 comments.
  • Lasse Ledet

    Lasse Ledet 3 months ago

    @Elle, no for the gears you are free to chose as long as they can be manufactured (preferably at a reasonable price). The material thickness is related to the changes you may do on the enclosure box as thicknesses below 1mm give rise to challenges for the injection molding process

    Lasse Ledet has uploaded 0 CAD models & has left 15 comments.
  • Elie VILLAIN

    Elie VILLAIN 3 months ago

    Thank you Lasse,
    I have an other question : Could it be possible to know roughly the frequency of use of the system ? (hour per day)

    Elie VILLAIN has uploaded 3 CAD models & has left 32 comments.
  • Pammeg

    Pammeg 3 months ago

    Hello,
    for me two things are not clear :
    1.If a constant speed (1 RPM) of output shaft is required (with variable speed 500-1500 RPM of the input motor), or a fixed speed ratio is allowed.
    2. If more than 360 degrees of output shaft rotation are allowed, on only one turn per direction is required.

    Pammeg has uploaded 6 CAD models & has left 10 comments.
  • Fredrik Lie Larsen

    Fredrik Lie Larsen 3 months ago

    Hi!
    Is the efficiency of the gearing a consideration? Assuming two solutions achieve 20Nm at 1rpm,would a higher efficiency transfer be preferred?

    Fredrik Lie Larsen has uploaded 15 CAD models & has left 58 comments.
  • Lasse Ledet

    Lasse Ledet 3 months ago

    @Elie: You may expect the operation sequence (3 sec. ON, 7 sec. OFF) to run 24 hours a day, 9 month a year.

    @Pammeg: 1) You should choose a fixed rpm of the motor and then pick the corresponding gear ratio to get 1 rpm on the output shaft. 2) Only 360 degrees in each direction is required, however, it is no problem if the solution can turn even more as long as it can do at least 360 degrees in both directions.

    @Frederik: In fact, the cost of the solution is more important than efficiency. You may consult the judging criteria above to see what is taken into consideration.

    Lasse Ledet has uploaded 0 CAD models & has left 15 comments.
  • Hans Kristian Bruun

    Hans Kristian Bruun 2 months ago

    The 20Nm is primarily to loosen the valve if it gets stuck. Are there any feedback forces from the valve? And do you prefer self-locking gear?
    What is the preferred IP-rating of the enclosure box?

    Hans Kristian Bruun has uploaded 4 CAD models & has left 8 comments.
  • Viktor Bazarov

    Viktor Bazarov 2 months ago

    Why did you change requirement from "no fixed gear systems" to "free of choice" in a mid of challenge ?

    Viktor Bazarov has uploaded 4 CAD models & has left 7 comments.
  • Lasse Ledet

    Lasse Ledet 2 months ago

    @Hans: Assume that there are no feedback forces. The valve itself is self-locking, so it is not a requirement for the gear system. The enclosure box (red) itself incl. its lid (not shown) seals off the gear system from the environment and therefore there are no requirements for the IP-rating of the gear system as it is inside the enclosure box.

    @Viktor: Unfortunately, the wording “no fixed gear systems” has caused confusion and therefore a clarification was needed. The meaning is the same as the original one, which was somewhat clarified in the comments above. The idea is that you are not required to use any special gear system i.e. you are free to choose e.g. planetary gears, worm, mesh, spur etc. And of course, you may choose fixed as well as variable gear ratio systems.

    Lasse Ledet has uploaded 0 CAD models & has left 15 comments.
  • Sanyog Lamsal

    Sanyog Lamsal 2 months ago

    Hello.
    Will the gear system be made in-house or are they imported? If there are any manufacturing constraints for the gear system, please mention it. Or, is it supposed to contain only standard components?

    Sanyog Lamsal has uploaded 14 CAD models & has left 17 comments.
  • Sanyog Lamsal

    Sanyog Lamsal 2 months ago

    Are hysteresis and backlash synonymous ?

    Sanyog Lamsal has uploaded 14 CAD models & has left 17 comments.
  • Fredrik Lie Larsen

    Fredrik Lie Larsen 2 months ago

    @Lasse Ledet Where on the output shaft is the oldham connection intended to be mounted? Between the output and the valve, or between the output shaft and the rest of the gear system, on the inside of the enclosure? :)

    Fredrik Lie Larsen has uploaded 15 CAD models & has left 58 comments.
  • Chris Tziros

    Chris Tziros 2 months ago

    1) What is the method via which our last gear will be connected to the output shaft (e.g. keyway, press-fit, set screw, hex-drive)?
    2) Is the connection between our last gear and the output shaft going to be made during the gear unit assembly or during valve instalation on site?

    Both of these questions aim in the proper bearing arrangement selection
    Basically i am trying to understand whether the bearing can be placed on the output shaft after the output shaft has already been connected with our last gear, and whether the bearing can ride on the ouput shaft itself (bearing ID=20mm).

    Chris Tziros has uploaded 19 CAD models & has left 70 comments.
  • Lasse Ledet

    Lasse Ledet 2 months ago

    @ Sanyog: It is entirely up to you whether you want your design to consist of standard components or be manufactured in-house. As mentioned above you may assume a large volume. You may think of hysteresis as the accumulated backlash throughout the entire gear system i.e. when the direction is changed, how many revolutions will it take before the output shaft starts to move. This is typically represented as the corresponding angle on the output shaft i.e. < 3 degrees.

    @Frederik: The Oldham coupling is between the output shaft and the valve. You do, however, not need to account for it in your submission.

    @Chris: 1) You may decide which connection you prefer. 2) Nothing will be assembled on-site, everything should be assembled prior to installation. Thus, you are free to choose the order you would like to assemble the unit in.

    Lasse Ledet has uploaded 0 CAD models & has left 15 comments.
  • Juan Arroyave

    Juan Arroyave 2 months ago

    If you want 300N at the tip, it means that the final power is 15000NM because the tip of the shaft measures 2cm, then T1 (300N) / 2cm = T2 / 100cmm. therefore T2 = 300N x 100cm / 2cm which gives T2 = 15000 NM

    Juan Arroyave has uploaded 394 CAD models & has left 381 comments.
  • Lasse Ledet

    Lasse Ledet 2 months ago

    @Juan: The force acting on the tip has mostly something to do with forces created by e.g. misalignment and this force does not produce any torque as it is a radial force that may be at any arbitrary angle. So, this force must be taken by either the gear system or by a bearing placed in the enclosure box. The choice is yours.

    Lasse Ledet has uploaded 0 CAD models & has left 15 comments.
  • Fredrik Lie Larsen

    Fredrik Lie Larsen 2 months ago

    @Lasse Ledet Can we change the diameter of the output shaft ( green )? It seems needlessly thick for just 20Nm :)

    Fredrik Lie Larsen has uploaded 15 CAD models & has left 58 comments.
  • Lasse Ledet

    Lasse Ledet 2 months ago

    @Frederik: Sure, it is rather thick for the 20Nm but there are other reasons for having this thickness. However, you may change the diameter of the part of the shaft that is inside the enclosure box.

    Lasse Ledet has uploaded 0 CAD models & has left 15 comments.
  • Vaughan Thomson

    Vaughan Thomson 2 months ago

    Nice challenge. What level of detail are the judges looking for? For example, should all fasteners be modeled?

    Vaughan Thomson has uploaded 1 CAD models & has left 6 comments.
  • Juan Arroyave

    Juan Arroyave 2 months ago

    @Lasse Ledet, Is possible you give us the electric motor power??? or torque??? Thanks for your collaboration

    Juan Arroyave has uploaded 394 CAD models & has left 381 comments.
  • Nic

    Nic 2 months ago

    In regards to the 30% duty cycle of the motor (3s on, 7s off) and the determination that the output should operate at 1rpm, is that to say the instantaneous shaft speed should be 1rpm, or should the shaft complete a full revolution in 1 minute, i.e. the instantaneous speed should be 3.3rpm?

    Nic has uploaded 26 CAD models & has left 89 comments.
  • Nic

    Nic 2 months ago

    It seems an impossible task if the required speed is 3.3rpm given the 20Nm requirement?

    Nic has uploaded 26 CAD models & has left 89 comments.
  • Vaughan Thomson

    Vaughan Thomson 2 months ago

    Another question regarding the wall thickness of the red enclosure. I understand that the outer shape must remain the same and additions internally for gear support is allowed. Are are we allowed to reduce the wall thickness in any areas by removing material from the inside of the red enclosure? Whilst keeping with the minimum thickness of 1mm?

    Vaughan Thomson has uploaded 1 CAD models & has left 6 comments.
  • Lasse Ledet

    Lasse Ledet 2 months ago

    @Vaughan: 1) The level of detail is up to you. But of course, the judges are able to see past a few missing fasteners. 2) The enclosure box has its own requirements and therefore the thickness specified. However, there is no problem in removing material locally inside the enclosure as long as you cope with the 1mm requirements.

    @Juan: In the attached material you’ll find a torque vs. RPM graph for the motor from which to can deduce the torque.

    @Nic: The duty cycle should not be accounted for in this regard i.e. the instantaneous speed is the 1rpm.

    Lasse Ledet has uploaded 0 CAD models & has left 15 comments.
  • Vaughan Thomson

    Vaughan Thomson 2 months ago

    @Lasse: Thanks for the feedback.

    Vaughan Thomson has uploaded 1 CAD models & has left 6 comments.
  • Vaughan Thomson

    Vaughan Thomson 2 months ago

    I am wandering now about the sealing of the enclosure at the 20mm shaft. In previous comments it has been made clear that the 20mm shaft can be stepped down on the inside of the box. would it be acceptable to step the 20mm shaft down before it enters the box and reduce the hole size to suit? Also will there need to be a provision for a running seal or alternatively would an exposed bearing be allowed here?

    Vaughan Thomson has uploaded 1 CAD models & has left 6 comments.
  • e.g.oussama

    e.g.oussama 2 months ago

    you accept STL file

    e.g.oussama has uploaded 27 CAD models & has left 285 comments.
  • Vaughan Thomson

    Vaughan Thomson 2 months ago

    I would like to know if the motor shaft can carry radial and/or axial load. If so what amount?

    Vaughan Thomson has uploaded 1 CAD models & has left 6 comments.
  • Lasse Ledet

    Lasse Ledet 2 months ago

    @Vaughan: The shaft should be stepped down inside the box, however, you need not worry too much about sealing of the shaft; a simple bearing will do. There are no axial forces, but a radial force of 300N (as specified) and this force is rotating, meaning that it may be at any arbitrary angle.

    @E.g.oussama: We do prefer STEP files, but if no other options an STL will do.

    Lasse Ledet has uploaded 0 CAD models & has left 15 comments.
  • Netanel Segev

    Netanel Segev 2 months ago

    Hi Lasse, Can we add Ribs in the inner side of the Enclosure box, but outside of the Space-Design Env. to give the Box structural strength? the gears and the motor along with the bearings is inside the Space-Design Env. and the ribs dont take any factor for the gear train or motor inside the Space-Design Env.

    Farther more, in the PDF, the Space-Design Env. is with extra circule EX-BOSS, which means we can use this space as well, is that correct?

    Thanks,
    Nate Segev

    Netanel Segev has uploaded 3 CAD models & has left 7 comments.
  • Lasse Ledet

    Lasse Ledet 2 months ago

    Hi Nate. No worries, as long as it is on the inner surfaces of the enclosure box you may add ribs etc. as you like (maybe keeping in mind the manufacturing constraints for the box). It is only the gear system that must be within the design space. And you may also use the extra circle of the design-space env.

    Lasse Ledet has uploaded 0 CAD models & has left 15 comments.
  • Netanel Segev

    Netanel Segev 2 months ago

    @Lasse Ledet, Thank you!

    Netanel Segev has uploaded 3 CAD models & has left 7 comments.
  • Alex Y.

    Alex Y. 2 months ago

    Just wondering why the deadline shows 11 hours remaining, but current EST is 08:30 am. I guess EST is obligatory?

    Alex Y. has uploaded 55 CAD models & has left 776 comments.
  • Muhammad Jabroot

    Muhammad Jabroot 2 months ago

    How any one add an entry??

    Muhammad Jabroot has uploaded 2 CAD models & has left 1 comments.
  • Kesa

    Kesa 2 months ago

    @Muhammed You must upload your entry on the GrabCAD Community and use the tag "GrundfosChallenge2019" and it will count. As it states in the rules section. Please look over the Rules if you aren't sure about submitting an entry.

    Kesa has uploaded 1 CAD models & has left 81 comments.
  • Ananth Narayan

    Ananth Narayan 2 months ago

    Wow so much entries.

    Ananth Narayan has uploaded 63 CAD models & has left 280 comments.
  • Alex Y.

    Alex Y. 2 months ago

    There are some very nice solution submitted =)

    Alex Y. has uploaded 55 CAD models & has left 776 comments.
  • ZBH

    ZBH 2 months ago

    Good luck everyone..may the best solution wins

    ZBH has uploaded 50 CAD models & has left 35 comments.
  • Nic

    Nic 2 months ago

    Quick question for GrabCAD community, I have three GIFs in my project and one doesnt play, is there a file limitation for GIFs in the gallery? The others are the same length and play fine.

    Thanks again and good luck to all.

    Nic has uploaded 26 CAD models & has left 89 comments.
  • fuad syaifuddin

    fuad syaifuddin 2 months ago

    thanks u the grundfos challenge

    fuad syaifuddin has uploaded 6 CAD models & has left 5 comments.
  • Alex Y.

    Alex Y. 2 months ago

    @Nic: Some (bigger) GIFs take a long time to be processed when uploading or editing a project. You can see that .jpg images get process quickly and the thumbmail is there, during the GIF has no thumbnail. If you wait some time (it may take 30mins or more) the GIF should be processed and you can save the project.
    Just try this.

    Alex Y. has uploaded 55 CAD models & has left 776 comments.
  • Nic

    Nic 2 months ago

    Thanks for the help Alex! I recreated the first GIF to be slightly smaller, all good now in my gallery. Cheers

    Nic has uploaded 26 CAD models & has left 89 comments.
  • Sava Savov

    Sava Savov about 2 months ago

    A "brilliant" idea came to my sick mind, how this challenge can become more interesting! And it is:
    After the finalists announcement, the participants send to GrabCad 10 $ and bet who will be the winner. Once the winner is announced, the money raised is distributed to those who have made the correct assumption (GrabCad takes something too, of course).
    This will be a kind of second chance for all of us, if we are in the number of these, who didn't make it well.
    In case nobody guess the winner (that is most likely),the money goes in fond for awards for new challenge, which GrabCad can organizes in near future.
    This will be some kind of publics vote, too.
    By the way, the voters can be all 6 million members if they be invited - massive gambling! :)

    Sava Savov has uploaded 18 CAD models & has left 114 comments.
  • Francisco Taveira

    Francisco Taveira about 2 months ago

    When and how will the finalists be announced?

    Francisco Taveira has uploaded 2 CAD models & has left 4 comments.
  • Kesa

    Kesa about 2 months ago

    Finalists and Winners will be announced here. Also due to this week being Thanksgiving in the USA they will be announced early next week. Sorry for any inconvenience this may pose.

    Kesa has uploaded 1 CAD models & has left 81 comments.
  • Ananth Narayan

    Ananth Narayan about 2 months ago

    Hello @Kesa, when will the finalist be announced. Can I get date and time.

    Ananth Narayan has uploaded 63 CAD models & has left 280 comments.
  • V.Novacov

    V.Novacov about 2 months ago

    Read the article "Schedule" above

    V.Novacov has uploaded 9 CAD models & has left 33 comments.
  • Francisco Taveira

    Francisco Taveira about 2 months ago

    The schedule above is outdated, at least regarding the finalists annoucement.

    Francisco Taveira has uploaded 2 CAD models & has left 4 comments.
  • Kesa

    Kesa about 2 months ago

    Finalists will be announced today.

    Kesa has uploaded 1 CAD models & has left 81 comments.
  • Mišel Ciglarić

    Mišel Ciglarić about 2 months ago

    I really don't understand why vvelox.solutio-1 solution i better over my. He uses worm gear and that can't be better than spur gears. Spurs have bigger efficiency. It looks fancy but that's not better than mine.

    Mišel Ciglarić has uploaded 1 CAD models & has left 22 comments.
  • TB rose

    TB rose about 2 months ago

    Honestly,the least the jury team should have done was to take a quick look at the selected finalist design reports.There are designs that dont meet even the torque and angular velocity requirements at the output shaft.I think it is disheartening to all the contenters that their ideas and hardwork was just worth less than one minute eyeballing to judge it.I think it is shamefull on the part of the company.Dont get me wrong some of the finalist designs really deserve to be there and are very impressive and well-though.

    TB rose has uploaded 1 CAD models & has left 3 comments.
  • Dani Epstein

    Dani Epstein about 2 months ago

    First of all, congratulations to all the finalists! Given the sheer amount of entries this might be too much to ask, but would it be possible to give a brief comment on the rest of the entries as to why they failed to make it to the finals?

    Dani Epstein has uploaded 1 CAD models & has left 6 comments.
  • Lasse Ledet

    Lasse Ledet about 2 months ago

    “Hello world” would be the appropriate thing to say when sending out this message as nations from all over the world has participated in this Grundfos Challenge. We have been extremely impressed to see such high participation, passion, diversity and inventiveness on what is more or less a classical topic of mechanics. By the end of the Challenge there were an amazing 113 submissions with everything from, belt drive, worm, hypoid, planetary, spur and other gear types to make the transmission from motor to shaft. Truly impressive work! On behalf of Grundfos, we would like to thank all of you who participated. We hope it has been as fun and challenging for you as it has been for us.

    Now, all the candidate solutions have been analyzed and we found that the majority was beyond what one could expect. Yet, 10 solutions have impressed the judges and therefore, we can, as of today, announce the Top 10 finalists, who will continue to the Grand Final. The winner of the 3rd, 2nd and, not least, the 1st prize will be announced later this week. Best of luck to everyone!

    Lasse Ledet has uploaded 0 CAD models & has left 15 comments.
  • Nic

    Nic about 2 months ago

    Congratulations to the finalists, there's a good range of solutions put forward. I'll throw my support to velox with the hypoid/worm gear set and to blackunicornengineering with the harmonic drive. They both used similar concepts to my entry Grundfos Grunty Hydronic Valve .

    For blackunicorn, I would say it would be more cost effective to have the harmonic gear set at the initial stage thereby saving cost.

    For velox, perhaps the axial load of the worm on the motor would compromise longevity of the motor bearing, as Sava commented.

    As with everyone, I had high hopes of contending the final, but with all these challenges, I take away lessons learned and experience gained.

    Cheers

    Nic has uploaded 26 CAD models & has left 89 comments.
  • Alaek Nu'man

    Alaek Nu'man about 2 months ago

    https://www.green-mechanic.com/2014/05/advantages-and-disadvantages-of_7.html?m=1

    Hopefully can be taken into consideration in determining the type of gear that is suitable for application to the system.

    Alaek Nu'man has uploaded 3 CAD models & has left 12 comments.
  • fuad syaifuddin

    fuad syaifuddin about 2 months ago

    thanks you

    fuad syaifuddin has uploaded 6 CAD models & has left 5 comments.
  • Sava Savov

    Sava Savov about 2 months ago

    I learned a lot from that challenge. Before it I didn't know how to calculate the ratio of a planetary gear - now I can do it in two ways (for the second way - thanks to Thomas Sutrina). I also got acquainted with these hypoid, cycloid, harmonic, ratchet-based gears - it was very interesting. In fact from all the solutions I learned something. I became richer! Thanks to all.
    @Nic By the way, even though I think I understood the harmonic gears, I can't figure out what blackunicorn is trying to spin with the largest gear wheel? It is mounted somewhere on the corpus of harmonic gearbox. But this gearwheel must spin the wave generator (the elliptical part which is inside the box) isn't it ???

    Sava Savov has uploaded 18 CAD models & has left 114 comments.
  • Alaek Nu'man

    Alaek Nu'man about 2 months ago

    https://en.m.wikipedia.org/wiki/Cycloidal_drive

    additional reverence for cycloidal drives

    Alaek Nu'man has uploaded 3 CAD models & has left 12 comments.
  • Nic

    Nic about 2 months ago

    @Sava - blackunicorn has a pretty good design doc which shows a cross section through the flexible gear and the elastic bearing. The ring gear drives the elliptical bearing which drives the flexible gear on the main shaft. I was looking at the same topology myself but the commercial units I found didn't fit the envelope for the required torque spec. That's why I moved the harmonic gear to the first stage where it was smaller, cheaper, and had less stress.

    Nic has uploaded 26 CAD models & has left 89 comments.
  • Alien_F1_Space

    Alien_F1_Space about 2 months ago

    Good morning .. It's not important project challenges. Because The model I upload is being downloaded by many people, I am not interested that the people downloading my model. I think I should leave with GrabCad challenges .I join new website projects to myself .. Thanks..

    Alien_F1_Space has uploaded 41 CAD models & has left 11 comments.
  • Sava Savov

    Sava Savov about 2 months ago

    @Nic
    Hmm… I decided to look closer to BlackUnicornEngineering’s gear box.
    Ratio 442
    When motor rotates with the min rpm=500 the output shaft will have 500/442=1,1 rpm. It can be reached about 20 Nm on output shaft when the motor starts (maxT1=0,053 Nm, ratio=442 and if the efficiency of spur gear is 0,98 and for harmonic drive is 0,9 we get 0,053*442*0,98*0,98*0,9=20,25 Nm). When motor rpm = 500 the max T-output =0,0435*442*0,98*0,98*0.9=16,6 Nm. So far so good.
    But I really think he messed things up with the harmonic gear – he mounted the gear wheel, which has to drive that harmonic unit, to the so called “internal gear” of the unit. If the output is the flex gear, the internal gear must be fixed. If the output is internal gear, the flex gear must be fixed. But the input always is the elliptic cam. Here BlackUnicornEngineering made the internal gear as input gear and even leaved the elliptic cam part free which leads to a situation where there will be no any reduction – the internal gear and the flex shaft will work as one part. So this design needs to be reworked – the input must be the elliptic cam and the internal gear to be fixed. And last but not least, the price even only of the harmonic unit is scary for mass use - 360 euros.

    Sava Savov has uploaded 18 CAD models & has left 114 comments.
  • Alex Y.

    Alex Y. about 2 months ago

    @Sava: One point is important for this challenge - the EFFICIENCY! Most of us has done estimations for this but at least the certain concepts needs to be validated in hardware. Here the real efficiency will come out. If the torque requirement is still fixed within 20±1Nm some concepts would be needed to adjust the ratio depending on the test results.

    Alex Y. has uploaded 55 CAD models & has left 776 comments.
  • Alex Y.

    Alex Y. about 2 months ago

    To leave some words on the concepts:
    The both cycloidal gearboxes have enormous advantages concerning the easy assembly. It can be seen in my animation. I also have some hardware parts of a cycloidal geabox so I can talk about it from my own experience: NO tools needed, only stacking the parts together!
    Also the manufacturing of prototypes would be very easy due to modern technologies available cycloids are not a challenge anymore.
    In my eyes the way from the concept phase here @ the challenge towards the first working prototypes is very short with cycloidal gearboxes.
    Furthermore there is a big potential regarding serial production since there are a lot of manufacturing possibilities and materials so industrialization will be easier, additionally advantaged by the low number of parts.

    Alex Y. has uploaded 55 CAD models & has left 776 comments.
  • Elie VILLAIN

    Elie VILLAIN about 2 months ago

    Happy to be one of the finalists. Thanks to grabcad and Grundfos for organizing such an interesting competition. I had a lot of fun and learned a lot by doing it. It also allowed me to dive back into my old student knowledge... It's not polite to vote for yourself, so I'd say the proposal Dual Cycloidal Gearbox by alex.y-1 is the one that deserve to win (Smart & well documented). Let the best win :)

    Elie VILLAIN has uploaded 3 CAD models & has left 32 comments.
  • Sava Savov

    Sava Savov about 2 months ago

    @ Elie Villain
    OK, then for ballance I will vote for Multi stage radial tandem harmonic gear box by Dario D'Amico. I like your design too but it has a small problem as you know.

    Sava Savov has uploaded 18 CAD models & has left 114 comments.
  • Alex Y.

    Alex Y. about 2 months ago

    Thank you very much, Elie!
    At least there is one reason to vote for the own model: You have surely evaluated different concepts and have chosen this certain one, because you rated it to be the best solution among your research. So you worked out the best solution! :)
    Your design is great, it is well documented, nicely presented... So don't be modest ;-)
    Also I agree with you - We had a lot of fun during this challenge and learned a lot of new things!

    Alex Y. has uploaded 55 CAD models & has left 776 comments.
  • BlackUnicornEngineering

    BlackUnicornEngineering about 2 months ago

    Thank you all beeing part of this challenge. It was a lot fun working on it and, for sure, seeing all this awesome solutions. Special thanks to the GrabCAD team for providing this platform and giving us a lot great oppertuneties showing our skills. Thanks to Grundfos for making this challenge happen and trusting our engineering community. I wish all of the finalists the best of luck. =)

    BlackUnicornEngineering has uploaded 9 CAD models & has left 1 comments.
  • Vaughan Thomson

    Vaughan Thomson about 2 months ago

    My 3 favorites are Alex, Elie and Velox submissions. They are all quite elegant solutions although I haven't looked at the details vs requirements. It seems like one of them exceeds the design space and another may be quite heavy. Good luck to the judges in picking the winners and thanks for the opportunity.

    Vaughan Thomson has uploaded 1 CAD models & has left 6 comments.
  • Ananth Narayan

    Ananth Narayan about 2 months ago

    It's my time for the vote:

    1. Grundfos Challenge - Dual Cycloidal Gearbox by alex.y-1

    2. Split-gear unit by chris.tziros-1

    All the designs are and I am happy that this platform thought me many information, accomplished my dream (To make the design popular so that it comes in home page)

    Thanks a lot guys. We will wait for the good.

    Ananth Narayan has uploaded 63 CAD models & has left 280 comments.
  • Sergey Taranets

    Sergey Taranets about 2 months ago

    Hello All
    ...Great design, great presentation ... - what else is needed to win?
    Dear gentlemen, you offer very boring solutions.
    All finalists solved the problem only by manipulating the value of the efficiency:
    • Selecting a point on the graph of motor characteristics
    • Selection of the gear chain with the necessary gear ratio
    • Multiple of efficiency values of all steps
    • Checking the result: 1 rpm 20 (+/- 1) Nm
    Only one of the finalists suggested a way to remove the lateral clearance of the entire chain of gears ... or does hysteresis no longer matter? We can talk about the manufacture of gears without play, but it will be a “golden” gearbox.
    Sorry, but this is the level of a students.
    This is a particular solution to the problem.
    For example, 3 points - 500, 1000, 1500 rpm.
    Here the permissible error for solving within the limits of the problem conditions is +/- 1/500, 1/1000, 1/1500 Nm
    This is a very small range of permissible torque error.
    This is close to the level of the internal motor friction.
    Is there any certainty that the motor manufacturer will ensure repeatability in mass production?
    Is there any guarantee that your efficiency calculations are correct? - this can only confirm real tests of a real gearbox.
    A virtual simulator cannot take into account all the factors.
    No problem if such a decision suits the sponsor.
    I apologize for the harsh judgment and my low rating of your technical solutions. I tried to find a more general and more correct solution.
    My solution (a magnetic coupling built into the 2nd stage) involves a wider range of input torque, while the torque at the output of the gearbox will be nominal (20 Nm) and it can be adjusted in each instance of the gearbox.
    But I have very poor English and not a bright presentation. By the condition of participation in the competition, I agree to any decision of the jury, but I have the right to my own opinion.
    I ask a jury (or the GrabCAD administration) to exclude my projects from this Challenge.

    Sergey Taranets has uploaded 186 CAD models & has left 275 comments.
  • Sanyog Lamsal

    Sanyog Lamsal about 2 months ago

    I'm rooting for Alex. All the best to everyone !

    Sanyog Lamsal has uploaded 14 CAD models & has left 17 comments.
  • Sava Savov

    Sava Savov about 2 months ago

    I invented the warm water! And you guys stole it from me!
    Voibor, was you the one who invented the bow and arrow? Do not be silly, the history doesn't starts from you.

    Sava Savov has uploaded 18 CAD models & has left 114 comments.
  • Alex Y.

    Alex Y. about 2 months ago

    Some news here: The jury has just commented the finalist's models! Seems that they will come to an end soon =)

    Alex Y. has uploaded 55 CAD models & has left 776 comments.
  • Sava Savov

    Sava Savov about 2 months ago

    I am sure that their decision will surprise all - it always happen like that :)

    Sava Savov has uploaded 18 CAD models & has left 114 comments.
  • Chris Tziros

    Chris Tziros about 2 months ago

    I think there must be a mistake implemented in “BlackUnicornEngineering” named “Grundfos Challenge Gearbox” that is severely affecting the output torque.
    The challenge's criteria require an output shaft torque equal to 20Nm +/- 1Nm (at 1 RPM) while the design seems to have taken a required torque of 16Nm, as it is stated in the "Project Summary" of the particular submission.Considering a gear ratio of "437.5", that seems to be adopted, the output torque at 1RPM is only 11.08 Nm.

    I neither question nor criticize the judge’s selection and decisions. I simply thought right to mention the above point just in case the error was omitted.

    Chris Tziros has uploaded 19 CAD models & has left 70 comments.
  • Mišel Ciglarić

    Mišel Ciglarić about 2 months ago

    Is it possible to check if those finalists or anybody else does not have opened second profile after they saw some solutions?

    Mišel Ciglarić has uploaded 1 CAD models & has left 22 comments.
  • Mišel Ciglarić

    Mišel Ciglarić about 2 months ago

    Velox is member since 19. November and he uploaded this model on 19. November which is similar to mine.

    Mišel Ciglarić has uploaded 1 CAD models & has left 22 comments.
  • Mišel Ciglarić

    Mišel Ciglarić about 2 months ago

    With idea of spiroid

    Mišel Ciglarić has uploaded 1 CAD models & has left 22 comments.
  • Alex Y.

    Alex Y. about 2 months ago

    Hello Sergey,
    thank you for the extensive response! You are surely right with your approaches to limit the output torque with a magnetic clutch.
    But anyway I have to defend all the “boring” entries, because the also fulfilled the requirements. Since this is a special type of project work, there is no communication with the “client” and all the requirements are defined in the description of the challenge. Therefore the description demands the best solution – low cost and weight, no maintenance, quick assembly, high efficiency and very exact definition of the operating point.
    Of course it is not possible to fulfill all those requirements to 100% so it is the decision of the designer to distribute the rating of the different requirements. As the operating point is exactly defined it is pretty obvious that you have to make an efficiency estimation to achieve a best fit solution with the given motor output torque. There is no doubt that you will need to validate the solutions with several tests but this is just normal development process. Nobody can develop a gearbox which needs no testing. Your design is a very good proposal for testing the gearbox prototype at different load points by limiting and varying and the output torque. But this is only one among of 100 others.
    To sum up – there is no unique and 100% correct solution for this task and in the end it will be the subjective decision of the jury how they evaluate every single entry. For this they gave us a very good guideline and Lasse also has answered a lot of questions here. That are the rules and we have to accept it.
    By the way, I think that the most of the participants here are actually students. They are gaining experience during this challenge and with this they are improving the “level of students” to become an experienced designer some day!

    Alex Y. has uploaded 55 CAD models & has left 776 comments.
  • Velox Solutio --

    Velox Solutio -- about 2 months ago

    VELOX SOLUTIO would like to thank all of our fellow participants in this challenge, as well as the teams at GrabCAD and GRUNDFOS that have given us the opportunity to participate. This is the first time that we have entered a GrabCAD challenge, and we have had a lot of fun during the whole process. We are very thankful to be amongst the 10 finalists and we wish the very best of luck to all of the other entrants that have reached this stage!

    Velox Solutio -- has uploaded 1 CAD models & has left 3 comments.
  • Sergey Taranets

    Sergey Taranets about 2 months ago

    @ Alex Y.
    As students, they are too conservative :(
    ... and the jury is probably also students

    Sergey Taranets has uploaded 186 CAD models & has left 275 comments.
  • Mišel Ciglarić

    Mišel Ciglarić about 2 months ago

    I am not saying that somebody has steal my idea for hypoid. This is brainstorming and it's normal that somebody's idea is developing by other's over time. Everybody should be aware of that. For example, the next stage for solution after spur and worm gear with hypoid will be hypoid with ratio of 60:1 and planetary gear with ratio 10:1. This will give us high efficiency and will probably solve this challenge problem. Or not?

    Mišel Ciglarić has uploaded 1 CAD models & has left 22 comments.
  • Sava Savov

    Sava Savov about 2 months ago

    I don't think anyone has to worry about this backlash at all. This backlash will be the sum of:
    First - the angle to which the output shaft will rotate owing to the play (luft, clearance, backlash) of last stage. Еvery following angle which will be added to that first angle will be smaller and smaller and smaller because now our system acts as multiplicator.
    Let's say that we have five stages with equal ratio i=3,5". Let's take for example an enormous value for every stage backlash - the backlash angle for each stage to be 1 deg.
    So the whole backlash of the output shaft will be:
    1+1/3,5+1/(3,5*3,5)+1/(3,5*3,5*3,5)+1/(3,5*3,5*3,5*3,5)=1,374 deg
    Even with so high value of backlash in gears we get more than half smaller value for the backflash on output shaft from 3 deg.

    Sava Savov has uploaded 18 CAD models & has left 114 comments.
  • Sava Savov

    Sava Savov about 2 months ago

    And if in previous example we take 2 deg backlash for each stage, again the result for the backlash of output shaft is smaller than 3. It is 2,795 deg

    Sava Savov has uploaded 18 CAD models & has left 114 comments.
  • Mišel Ciglarić

    Mišel Ciglarić about 2 months ago

    @ Sava. You are completely right about that. When you search in gearing theory and find backlashes for diferent gearing this become clear. But probably with multigearing system like with train spur gears backlash can exceed 3deg over time due to wear of material.

    Mišel Ciglarić has uploaded 1 CAD models & has left 22 comments.
  • Chris Tziros

    Chris Tziros about 2 months ago

    @Sava Savov your calculations are totally wrong.
    You do not divide the backlash with the gear ratio in order to get the total amount of it, it is actually the opposite, you multiply them and then add it. Any simple motion study would verify the point I am trying to make. Also i did actually carry a motion study for my original design, which had no anti-backlash mechanism, and the results showed a total backlash of around 400 degrees. All the gears used on the above study had a backlash of 0.1 mm which is a common tooth form and demands no special manufacturing process. The total backlash number may not be exact for every spur gear system but the hysteresis caused by the total backlash is actually significant which is probably why the criteria also states that they want a low hysteresis, and also the reason that many people decided to go with a cycloidal drive which would almost eliminate any backlash. By the way i would like to mention that i really like Alex Y.'s cycloidal drive design as well as his presentation and renders.

    Since there seem to be quite a lot of people that haven’t taken the time to do such a study or do not have the tools to do so, i have posted a picture below my submission (in the comments sector) that presents the results of a motion study proving my point.

    I do not know whether backlash and the hysteresis caused from it is going to play a significant role on the winner results but there is a great deal of backlash and it is not just 2-3 degrees as Sava Savov has mentioned.

    Good luck everyone.

    Chris Tziros has uploaded 19 CAD models & has left 70 comments.
  • Alaek Nu'man

    Alaek Nu'man about 2 months ago

    cycloidal gear system that has a low level of backlash, but this gear system has a high level of vibration.

    Alaek Nu'man has uploaded 3 CAD models & has left 12 comments.
  • Sergey Taranets

    Sergey Taranets about 2 months ago

    A bit of nostalgia ... More than 30 years ago, I was a young engineer who received the task of calculating the springs for split gears of a multi-stage gearbox (more than 20 steps). These were low torque gearboxes. I used hairpin (torsion) springs made of thin steel wire. For different steps, they could be twisted at a different angle and get a different moment. In this competition, I refused this option because the moment is relatively large and I have no way of calculating (simulating) the efficiency of friction of the back of the tooth ...
    chris.tziros is the only one to whom I gave a “like” for the decision.
    I wish him victory.

    Sergey Taranets has uploaded 186 CAD models & has left 275 comments.
  • Alex Y.

    Alex Y. about 2 months ago

    @Chris: This study is very cool, I will have a closer look later. I am very curious, how the jury will rate the different hysteresis behaviours of the finalist's gearbox concepts!
    @Alaek: That is correct, the eccentric drive causes some unbalance in the gearbox. To improve the vibration behaviour of cycloidal gearboxes a shortened cycloid curve is used, which reduces the eccentricity and therefore vibrations. I have uploaded a picture in the comments of my entry.
    For a valve application my thought was that the NVH is not the big issue, but we do not have any informations where this valve is used.
    Of course cycloidal gearboxes can't be used in e.g. pedelecs since there is no acceptance of vibrations by the customer.
    Maybe the jury will give us the informations later :)

    Good luck to you all for this competition!

    Alex Y. has uploaded 55 CAD models & has left 776 comments.
  • geo

    geo about 2 months ago

    My English is too poor to understand the required requirements for this competition. Gears or worm gears already exist and Grundfos has 19,000 employees.
    I can not imagine that Grundfos will benefit from the submissions.
    In my opinion, Grabcad competitions only make sense for design drafts.
    Grundfos is running in my basement. For many years.
    I appreciate this company.

    geo has uploaded 20 CAD models & has left 677 comments.
  • Velox Solutio --

    Velox Solutio -- about 2 months ago

    @Chris Tziros: in a gear train in order to calculate the total amount of backlash you must divide the backlash of any step by the gear ratio as Sava Savov saied.
    Moreover both warm gear and hypoid gear offer a very low backlash and a very low level of vibration.

    Velox Solutio -- has uploaded 1 CAD models & has left 3 comments.
  • Sava Savov

    Sava Savov about 2 months ago

    About my thoughts for backlash, I saw that more exploration is needed.
    Now I will continue with my previous virtual example: In this example I began to compensate the looseness in mechanism by rotating the output shaft further and in condition of stopped input shaft. Now I will start to compensate the looseness by rotating back the input shaft and in condition of stopped output shaft.
    Now the question is: How many rounds or turns must the input shaft make for the totally looseness in mechanism to vanish (when the output shaft has not any motion!)?
    First the input shaft have to compensate the looseness in first stage - we said that it is 1 deg (we assumed that there are 5 stages, in every stage the backlash angle is 1 deg and the ratio for every stage is 3,5). Then it will continue to rotate to compensate the looseness in second stage and that second angle, which will be added to the first angle, will be 1*3,5=3,5 deg. Then comes the third, fourth, and fifth angle. So the total backlash ON INPUT SHAFT when the OUTPUT SHAFT IS STOPPED will be:
    1+1*3,5+1*3,5*3,5+1*3,5*3,5*3,5+1*3,5*3,5*3,5*3,5=209,685 deg
    Here (output shaft is immobilized), when the input shaft has rotated ~210 deg, the whole looseness in mechanism will be compensated.
    In first part of the example (input shaft is immobilized) we saw that when the output shaft has rotated 1,374 deg, the whole looseness in mechanism will be compensated.
    Now, what will happen if the input shaft rotates in back direction and output shaft is rotated by some outside torque in back direction too? In this condition it is possible the looseness in mechanism to stay in some of the stages.
    What will happen if the input shaft rotates in back direction and output shaft is rotated by some outside torque in forward direction? In this condition the looseness in mechanism will vanish fast and the calculated values in the example will be smaller for the output shaft and for the input shaft.

    But we know that there is no driving torque at the output shaft. So the backlash for the output shaft will be zero – there will be backlash only for the input shaft when it changes its direction of rotation. And if we want to know how much displacement we “lost” for the output shaft, we have to calculate: “backlash angle of input shaft”/Ratio. For our example (ratio=3,5^5) the lost displacement for output shaft will be:
    209,685/525,219=0,4 deg

    Sava Savov has uploaded 18 CAD models & has left 114 comments.
  • Alex Y.

    Alex Y. about 2 months ago

    I agree, since the hysteresis is defined on the outputshaft you will not have any problems with gear backlash even when assuming 1° of backlash per spurgear stage. As you calculated it correctly the angle at inputshaft will be much higher so you have to rotate the onputshaft 210° backwards until the backlash is compensated.

    Alex Y. has uploaded 55 CAD models & has left 776 comments.
  • Chris Tziros

    Chris Tziros about 2 months ago

    @Sava Savov
    I don't really understand your explanation, something that ofcourse shouldn't come as a surpise since you are using numbers out of the blue without explaining them (525.219) and also make asssumptions without any proof "So the backlash for the output shaft will be zero"

    Anyway i will stick to my motion study results since they are far more expanatory than your words, also if there was no need for backlash compensation i think the criteria wouldn't even mention the hysteresis. No need to further discuss the issue, i think it must be a case of different prespectives.

    As always, good luck everyone.

    Chris Tziros has uploaded 19 CAD models & has left 70 comments.
  • Nic

    Nic about 2 months ago

    The most practical transmission, in terms of backlash, would likely be a harmonic drive which presents practically zero backlash at high ratios where the elliptical bearing is sufficiently preloaded. These are often used in CNC machines for this reason. Vibration would also be lower than a cycloidal gear set. My reference says harmonic drives do exhibit some velocity ripple, but for the case of a hydronic valve, it's of no concern. My 2 cents.

    Nic has uploaded 26 CAD models & has left 89 comments.
  • Mišel Ciglarić

    Mišel Ciglarić about 2 months ago

    @Nic. Biggest disadvantage of harmonic drive is production price. Nobody would buy this kind expensive regulator.

    Mišel Ciglarić has uploaded 1 CAD models & has left 22 comments.
  • Alex Y.

    Alex Y. about 2 months ago

    @Misel: I think that't the point about harmonic drive. Cycloidal drive is much cheaper - I know a serial production application, where cycloidal gearbox is used for parking lock engagement in an electric drive transmission. And if it is used in automotive sector it can't be expensive :D

    Alex Y. has uploaded 55 CAD models & has left 776 comments.
  • Kesa

    Kesa about 2 months ago

    Winners will be announced Tomorrow 12/6/2019

    Kesa has uploaded 1 CAD models & has left 81 comments.
  • Chris Tziros

    Chris Tziros about 2 months ago

    Thanks for letting us know Kesa!

    Chris Tziros has uploaded 19 CAD models & has left 70 comments.
  • Dario D'Amico

    Dario D'Amico about 2 months ago

    I think there is a misunderstanding about backlash and hysteresis.
    Even though they both produce inaccuracy at the output shaft position their causes are different. Backlash is because of geometrical clearance between the elements of the trasmission, hysteresis is because of the non ideal nature of materials. Hysteresis occurs only when some load is applied, backlash occurs always even with no loads.

    Given the nature of the application I think that limiting backlash is not really a priority, even in the spec there is no mention of backlash but hysteresis only.

    Backlash is more of a problem for applications like machine tools where you need accurate repeatability accross all of the range of movement, even when there's no load is applied.

    Dario D'Amico has uploaded 12 CAD models & has left 23 comments.
  • Tittoni Sotiris

    Tittoni Sotiris about 2 months ago

    Hi to all and good luck to the finalist!
    I agree with @geo and i was waiting to see the finalists just to understand what Grundfos looked for, a fancy design or a low-cost durable one. The real problem is how the mechanism withstands 9 months of continuous work.

    Tittoni Sotiris has uploaded 7 CAD models & has left 7 comments.
  • Chris Tziros

    Chris Tziros about 2 months ago

    @Dario D'Amico, your explanation might be correct but in the above comments Lasse Ledet has already given us more or less what we should think of when talking about hysteresis on this particular design by saying the following.
    "You may think of hysteresis as the accumulated backlash throughout the entire gear system i.e. when the direction is changed, how many revolutions will it take before the output shaft starts to move."

    Chris Tziros has uploaded 19 CAD models & has left 70 comments.
  • Mišel Ciglarić

    Mišel Ciglarić about 2 months ago

    @Cristian Oekerman: i did little look to your design and I don't understand how you achieve to get high ratio of 132 for cycloid gear? Is this only prediction? Can you please put little more technical explanation? Or somebody else please?

    Mišel Ciglarić has uploaded 1 CAD models & has left 22 comments.
  • Alex Y.

    Alex Y. about 2 months ago

    @Misel, he uses 2 stages the ratio is 12*11=132

    Alex Y. has uploaded 55 CAD models & has left 776 comments.
  • Mišel Ciglarić

    Mišel Ciglarić about 2 months ago

    Oh.. I see now:-) Well done Cristian! Very elegant approach. Tnx.

    Mišel Ciglarić has uploaded 1 CAD models & has left 22 comments.
  • Mišel Ciglarić

    Mišel Ciglarić about 2 months ago

    The problem with cycloid gears is that you need to have proper center distance for proper function. This can be big problem. If distance is to close that will generate tremendous radial force, if to far ratio will be lower.

    Mišel Ciglarić has uploaded 1 CAD models & has left 22 comments.
  • Alex Y.

    Alex Y. about 2 months ago

    You will need quite high quality of the parts anyway because low hysteresis is one of the requirements, independent of the gearbox type. Therefore I don't think there will be an issue with the eccenter tolerances.

    Alex Y. has uploaded 55 CAD models & has left 776 comments.
  • Francisco Taveira

    Francisco Taveira about 2 months ago

    First of all, I would like to emphasize how glad and proud I am to be in the finalists.
    I really apreciate all designs, and most of alld the cycloid and harmonic reduction concepts.

    I did not have the chance to check them in detail, because I'm since Tuesday early morning in the maternity house with a newborn daughter, checking stuff with a bad signal on my cellphone...

    Although I have one overall concern in mind, which is the output gears stress.
    Seems to me that most designs are optimistic about the efforts on the gear connected to the output shaft which delivers 20Nm. Even though I maximized the latest gear with the available design space, no more than 65mm diameter gear was possible, and with as thick as 10mm gear (m=1), appliyng Lewis calclaution returned 145MPa to the big gear and 275MPa to the one driving it, so I'm quite surprised to see such small gears on the output and materials as nylon being applied.

    Once again, I did not had the chance to check the calculations of the other designs, it's just the main concern seeing them out of the blue.

    Nevertheless, big cheers to all finalists and aeeryone who participated...

    Francisco Taveira has uploaded 2 CAD models & has left 4 comments.
  • Alex Y.

    Alex Y. about 2 months ago

    @Francisco: Congratulations to your newborn daughter, I wish you all the best! =)

    Alex Y. has uploaded 55 CAD models & has left 776 comments.
  • Francisco Taveira

    Francisco Taveira about 2 months ago

    @Alex, Many thanks! Couldn't be more excited :D

    Francisco Taveira has uploaded 2 CAD models & has left 4 comments.
  • Sava Savov

    Sava Savov about 2 months ago

    I think Francisco is the big winner - he have the biggest possible award - CHILD!

    Sava Savov has uploaded 18 CAD models & has left 114 comments.
  • Sava Savov

    Sava Savov about 2 months ago

    ...has..

    Sava Savov has uploaded 18 CAD models & has left 114 comments.
  • Sava Savov

    Sava Savov about 2 months ago

    By the way, it's around 7 pm in Denmark - and still no results. These people seem to continue to work in time that could nobody have to work. But it was said a long ago:
    "Something is rotten in the state of Denmark." :)

    Sava Savov has uploaded 18 CAD models & has left 114 comments.
  • Kesa

    Kesa about 2 months ago

    Winners have been announced. Thank you everyone for participating in the Challenge. Hope to see you all bring magnificent models into our future challenges.

    Kesa has uploaded 1 CAD models & has left 81 comments.
  • Sava Savov

    Sava Savov about 2 months ago

    I am not surprised that I am surprised :) Congratulations to the winners and all the best to all!

    Sava Savov has uploaded 18 CAD models & has left 114 comments.
  • Chris Tziros

    Chris Tziros about 2 months ago

    Really surprised not to see Alex Y. on the top three. Definitely a lot of quality work from his part, just like he always does.
    Anyway, congratulations to anyone that accepted the challenge and managed to come up with an assiduous result.

    Chris Tziros has uploaded 19 CAD models & has left 70 comments.
  • Sava Savov

    Sava Savov about 2 months ago

    It may looks ugly to post a kind of negative comment in this moment but the game is over and one comment more or less will not have big affect to anything. I am just talking to myself : You must have a sixth sense, third eye, eighteen open chakras, to know that some of the criteria you fulfil finally will be ignored by the judges - criteria, which they themselves have stated, and the judges will judge by other, hidden, unknown criteria. It was said 20 Nm as a must! But at the end comes up that the judges don't care about this thing?? So, why they put this as requirement? Full mystery...

    Sava Savov has uploaded 18 CAD models & has left 114 comments.
  • Alex Y.

    Alex Y. about 2 months ago

    Congratulations to the winners!
    @Chris: Well, I think I have stolen the wrong idea ;-) The other stolen idea has won :D

    Alex Y. has uploaded 55 CAD models & has left 776 comments.
  • Elie VILLAIN

    Elie VILLAIN about 2 months ago

    Thanks again to Grabcad and Grundfos for organizing this contest. Everyone did a very good job and deserved to win among the finalists... and in the end I had this luck... My design is certainly not perfect and certainly contains some mistakes. However,I think I made the difference because of the material used to meet the cost and non-lubrication constraints. I also spent a lot of time justifying all my choices by basing the study on the resistance dimensioning of gears. Thank you for rewarding my work, I learned a lot and had a lot of fun! :)

    Elie VILLAIN has uploaded 3 CAD models & has left 32 comments.
  • Dario D'Amico

    Dario D'Amico about 2 months ago

    Well, congratulation to the winners.

    This was a very interesting challenge, I would like to urge grabcad to provide us with more of them in the future.

    Dario D'Amico has uploaded 12 CAD models & has left 23 comments.
  • Velox Solutio --

    Velox Solutio -- about 1 month ago

    Our congratulations to the winners of this challenge!! It has been great fun participating and we will definitely repeat the experience. Many thanks to all the other participants, the finalists and, of course, the winners for having shared such stimulating proposals with all of us. Many thanks, also, to the GrabCad and Grundfos teams for their hard work during the challenge. I’m sure that the decision making process has not been easy for them!!

    Velox Solutio -- has uploaded 1 CAD models & has left 3 comments.
  • Mišel Ciglarić

    Mišel Ciglarić about 1 month ago

    Congratulations to the winners! Thank you GrabCad! Thank you Grundfos! Thank you all! I hope that this process was not discouraging for Grundfos and that they will give us more challenges here on Grabcad in near future.

    Mišel Ciglarić has uploaded 1 CAD models & has left 22 comments.
  • trinityscsp (Juarez)

    trinityscsp (Juarez) about 1 month ago

    Congratulations to the winners, really interesting ideas.

    trinityscsp (Juarez) has uploaded 1198 CAD models & has left 11382 comments.
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