Patent ID: 8677620
Filing Date: 2014-03-25
Classification: B21D,B23K,B23P,C21D,F01L,Y10T

Abstract:
1. A method for making cam shafts, by linking cam rings to a hollow shaft in an IHPF (Internal High Pressure Forming) process, the hollow shaft being deformed in said IHPF process to form a cam shaft, comprising the steps of providing surface-hardened cam rings of even thickness, an outer surface of each cam ring being hardened to produce a defined thickness area that is hard and elastic and to a minor extent plastically deformable, with an area below being plastically deformable, wherein the surface-hardened cam rings show a permissible residual expansion of >=0.5%, and providing the hollow shaft in form of a tube made from a material that is plastically deformable, and joining the surface-hardened cam rings and the hollow shaft in the IHPF process by internal pressure, whereby the hollow shaft is deformed to form cams under the surface-hardened cam rings and the surface-hardened cam rings are secured on the hollow shaft in a force-and form-closing manner, wherein the surface hardened cam rings are made from a low-alloyed spring steel.