Induction hardening of camshaft

摘要

In a camshaft hardening process in which cams (5a-c) are simultaneously induction hardened in groups while adjacent camshaft zones, which are not to be hardened, are shielded by a cooling device, the cam groups are simultaneously hardened by a linear inductor and heating up of the cams (5a-c) is carried out initially in one or more low power time intervals and finally in a high power time interval, the time intervals being separated by a pause interval in which no power is supplied. Also claimed is a linear inductor for carrying out the above process, having two or more heating conductors (2, 3) which extend axially parallel to the camshaft (4) in the region of the cam group generatrix and which are mutually offset by /}180 deg relative to the rotational axis (L) of the camshaft (4). The novelty is that (a) the length of the heating conductor branches (2, 3) corresponds to the distance between the outermost ends (5a', 5c') of the cam group; and (b) each heating conductor (2, 3) is in the form of a loop with two branches (2a, 2b, 3a, 3b) extending axially parallel to the camshaft (4), the first branch (2a, 3a) being offset by less than 90 deg to the second branch (2b, 3b) relative to the rotational axis (L) of the camshaft (4).