A blank optimization design method for three-roll cross rolling of complex-groove and small-hole ring

• Using stepped-section blank to form complex-groove and small-hole ring is proposed.
• Theoretical design formulas for blank design in TRCR are described.
• Blank shape and size influence the quality of this profile ring greatly.
• A BP-neural network prediction model for revising blank size is established.

Complex-groove and small-hole rings have the common geometric characteristic of asymmetric deep-groove on the outer surface and small-hole in the center, such as duplicate gears and double-side flanges. It is difficult to get the complete section profile directly by traditional forging or special ring rolling technology. Three-roll cross rolling (TRCR) is an advanced plastic deformation to form ring parts with deep groove, which can form the complete deep groove directly by three-roll rotary rolling. As a key to the design of TRCR, the blank design influences material flow and distribution as well as final shape of deep-groove. In this paper, the material flow behavior in TRCR of complex-groove and small-hole ring with rectangular section blank is analyzed by a theoretical approach. Through analysis, forming the ring with stepped-section blank is put forward, and a theoretical method to design the blank size is established. Then the possibility and shortage of the theoretical method are discussed by FE simulation. Therefore, a volume correction coefficient is proposed to correct the blank size. Further, a prediction model of the volume correction coefficient is established by using orthogonal simulation test and back propagation (BP) neural network. Finally, the blank design method is verified by simulation and experiment. The result shows that complex-groove and small-hole rings can be formed perfectly with blanks which are designed by the theoretical formulas and the prediction model.