SHAPESET: A process to reduce sidewall curl springback in high-strength steel rails

Abstract

High-strength steel rails for structural members can reduce vehicle weight, but sidewall curl springback in these rails causes assembly difficulties with adjacent parts. A process to greatly reduce curl springback, known as SHAPESET, was investigated for a variety of high-strength steels, including two dual-phase steels. Gridded blanks were stamped by the two-step SHAPESET process and by conventional methods. The SHAPESET process nearly eliminated sidewall curl and was not sensitive to material strength. The first step of SHAPESET stamps a preform to eliminate the shock line, which restricts the spread of strain in the sidewall. The second step firmly clamps the preform flanges, in order to strain the part to the final shape. In comparison, the curl springback could only be reduced in a conventional stamping process by increasing the drawbead restraining force, which tended to produce failure by splitting.