INDUCTION HARDENING METHOD OF PIN OF CRANKSHAFT AND INDUCTION HARDENING DEVICE THEREFOR

摘要

PURPOSE:To decrease an actual load applied to a pin and to reduce the range of variaction of actual load by controlling an opposite load for decreasing the load applied to the pin in accordance with the progress of hardening. CONSTITUTION:Hardening is executed by hanging a power transformer T and heating coil body C which is fixed in the lower part of the transformer at one end of a wire 33 and placing them on the pin Pi of the crankshaft K which is revolved while keeping the shaft center line K1 horizontally. At this time, to reduce the actual load on the pin P1, a 2nd load having a constant value in the opposite direction opposed to a 1st load of the transformer T and hardening coil C is generated on a piston 52 in a cylinder 51 with air pressure and this load is given to the other end of the wire 33. In the respective sections between a 1st intermediate point M and the top dead center U, the top dead center U and a 2nd intermediate point N, the 2nd intermediate point N and the bottom dead center L and the bottom dead center L and the 1st intermediate point U where the pin P1 passes while rotating, solenoid valves 91-94 are switched, the output air pressure from pressure-reducing valves 81-84 is introduced into the cylinder 51 and the 2nd load is changed from a constant value to the other constant value stepwise one or more times.