Theoretical analysis of the forging process for producing hollow balls

Hollow balls are used in the production of various machines and devices. The technology for producing hollow balls by metal forming technologies poses numerous difficulties connected with the forming of a hollow billet. The billet, which is usually in the form of a rod, is subject to such processes as forging, helical rolling or cross-wedge rolling. The paper discusses a new method and conditions for producing a hollow ball. It was assumed that the ball would be produced in two forging operations: an initial forging operation and finish forging operation. The presented results are based on the FEM numerical analysis conducted using DEFORM-3D. It was assumed that the billet material was made from AISI 304 stainless steel used to produce balls for ball valves. Both the shape progression during the forging process and variations in the forming force were analyzed. Based on the conducted analyses, it can be claimed that hollow balls can be produced using the proposed forging method.