Two-Step Spin Forming of Thin-Walled Heads with Lateral Normal Flanged Holes

Abstract

A thin-walled head with a lateral normal flanged hole is a key part of a propellant tank, and its low-cost and high-precision forming process is very challenging. In this paper, a two-step method is proposed to preform the head via marginal-restraint mandrel-free spinning and then to realize the flanging of the lateral normal hole using a punching–spinning method. Finite element analysis of round-hole punching–spinning flanging shows that the larger the thinning ratio and the roller fillet radius, the lower the rebound and contour rise amount; the larger the feed ratio, the lower the rebound and the higher the contour rise amount. Further study on the effects of round-hole punching–spinning flanging on the secondary deformation of thin-walled heads shows that the deformation of the head in the area around the flanging hole is less severe than that of the flat blank, and the deformation in the circumferential direction is different from that in the busbar direction. Finally, it is verified through experiments that the two-step method can realize the spin forming of thin-walled heads with lateral normal flanged holes.