Application of the theory of plasticity of the cold pilgering of tubes

Abstract

This paper deals with the appllication of the theory of plasticity to the cold pilgering of tubes, i.e. the presentation of an analytical model of the cold pilgering process, fundamental equations, some examples of calculations, and limited results of experimental operations. By using this theory, the stresses, strains, and roll-separating forces during the pilgering process are calculated theoretically, and also the characteristics of the cold pilgering process are demonstrated: calculated values are in close agreement with experimental data. In the industrial operation of this process, groove design is very important as the dimensional accuracy of the tubes and the life of the tools is highly dependent on this design: the presented theory can be successfully applied to this topic. By using the theory, the deformation of a tube can be calculated for given dimensions of the groove and mandrel: however, by applying this procedure conversely, it is possible for the appropriate groove dimensions to be determined. A new groove designed using this procedure has been applied to industrial operation of the process, and has brought about a marked improvement in the dimensional accuracy of tubes, and a dramatical increase in yield and productivity. The new groove has been applied successfully to various materials, e.g., stainless,steel, titanium, zirconium alloy, copper, and copper alloy.