how to model this screw with catia v5 http://cjoint.com/?DGvqrK7znGB
You can do like this:
1- in a sketch draw the half of the screw in order to shaft the sketch
2- the same with the head of the screw (optional) if you like to do in different sketch
3- in wire frame & surface module, draw an helix with Taper angle following the surface of the body screw (you must to take this measure)
4- draw the section or the screw and do a Rib with screw section ans Helix as guide.
If you do this.. you'll have something like the picture
good luck. I attach an example if you have doubts.. V5.19 release