To provide a method for hardening a cam shaft, capable of suppressing, a bending after hardening the cam shaft, and also arranging the depth of a hardening layer of a cam part in an each block.
The method for induction hardening is carried out by induction hardening a cam shaft 1 wherein a cam block having a plural number of cam parts is composed of a plural number of cam blocks 11 having a journal part within those cam blocks. In this induction hardening, the following processes are in turn carried out, which are composed of a) a transporting process to arrange the cam shaft 1 by penetrating into a coil ring of an annular heating coil 21a, b) a rotate-driving process to rotate the cam shaft 1 at a constant rotating velocity, c) a heating process to induction-heat the whole cam part at the same time a high frequency current is drew through the annular heating coil 21a, d) an air-cooling process to air-cool the cam shaft heated after the heating process, e) a cool-hardening process to cool-harden the whole cam part at the same time after air-cooling, and f) a carrying out process to carry the cam shaft 1 hardening-treated out.
KAWAHARA MASAJI
MIYASHITA KOICHI
