Material Flow Control and Process Design in Constraint Ring Rolling of Thin-Walled Conical Cylinders with Three Ring Ribs

Thin-walled conical cylinders with three ring ribs (TWCCTRR) are the critical bearing-load components of aerospace equipment, and now the high-performance fabrication of TWCCTRR is confronting great challenges. Constraint ring rolling (CRR) is a new plastic-forming technique that shows great potential in forming high-performance TWCCTRR. However, unreasonable material flow (UMF) is prone to occur in the CRR of TWCCTRR, which weakens its performance. Therefore, the problem of UMF in the CRR of TWCCTRR is investigated in this work. Through finite element (FE) simulation, it is found that UMF occurs at the bottom of the middle rib in single-pass CRR of TWCCTRR because the rib at the middle part is the earliest among the three ribs to be completely filled. Therefore, the double-pass CRR process is proposed for forming TWCCTRR without UMF, which makes the three ribs fully fill simultaneously to avoid UMF. Based on the FE simulation, in contrast to the single-pass CRR, the deformation homogeneity of TWCCTRR obviously improved, and meanwhile, the maximum radial forming force is approximately reduced by 15% in double-pass CRR due to the variation in material flow mode. Investigation results offer theoretical guidance for the CRR of high-performance TWCCTRR.