Shear spinning technology for manufacture of long thin wall tubes of small bore

Abstract

Metal spinning is a process in which the deformation stresses are localized to a small region. The material is made to flow and move over the rotating mandrel with the help of a spinning tool mounted on a saddle and moving along the profile of the mandrel. The process has been in use for a long time to produce axi-symmetric shapes and tubular products with small L/D ratio. However, the conventional process fails to produce long, thin-wall, small-bore tubes. The process has been modified to spin long, small-bore, thin-tubes in hard-to-work materials such as CP titanium, Incoloy 825, Inconel 600 and Stainless steel AISI-304. The technology of making tubes in the above materials has been developed. The effect of feed, roller profile, percentage reduction and lubricants used on the surface finish and the power consumption when working with AISI-304 is reported. It is observed that the mechanical properties of the product improve considerably, close dimensional tolerances are obtained on outside and inside diameters and the wall thickness, and high reductions are possible without intermediate annealing. The new process is economically viable for producing tubes in high-strength materials, particularly when the volume of production is not high. The special features of the modified machine are given also.