Forces required for cold rolling

[WardHollowayPE]

I need to design a machine to cold roll a taper onto a .5 inch shaft. Given the material and dimensions, and amount of displacement per revolution, I need a formula for calculating required load or pressure. I suspect the solution may involve the hardness or modulus of elasticity in compression. I also realize that during cold forming the process is in the non-elastic region.

Thanks in advance for any help.

 

[bvasa]

I can't give you the formula, but I can add a couple factors to it-
1. Surface area of contact between the forming tools and the shaft
2. Yield strength of the material (it changes during the process as the material is cold worked).
3. Lowering of the yield point by adiabatic heating, a side effect of the cold forming process.

Since all these factors can change during the course of forming one part, it's probably best to design to the max load condition.

For a couple examples of machine designs, you might look up swaging or wedge rolling.

http://www.felss.de

is one of several swaging machine manufacturers. I don't have a link for wedge rolling machines.

Good luck.