Rate of deformation and redundant shears in the combined rotary piercing-elongating process

Abstract

Abstract

The ultimate success of the new combined rotary piercing-elongating process for tube making will depend on the possibility of lessening the inherent severity of the operation. The reduction in the incidence and magnitude of redundant shearing strains will be therefore of primary importance.

The present work examines, experimentally, the influence of the predetermined rate of deformation on the redundant shear in the pass. It is shown that there exists a well defined relation between these strains and the geometry of the pass, and, hence, the rate of deformation.

It is concluded that a range of low feed angles should be used, and that a feed angle of 8°, combined with the decelerated rate in the piercing zone of the pass and a uniform rate in the elongating zone, is likely to provide a satisfactory compromise between the velocity requirement and the quality of the finished product.