| 摘要 |
<p>PURPOSE:To prevent local deformation of tooth part at quenching rear part of a steering rack and to facilitate the following correcting operation, by quenching tooth part and rear part in order by plane shaped induction coil at high frequency quenching tooth part and rear part having almost circular section. CONSTITUTION:The steering rack 1 is fixed to a high frequency quenching apparatus 16 with electrodes 7, 8, etc., while parallelly setting the tooth edge surface to plane surface of an induction coil 9, tooth part is heated under a prescribed condition, then coolant liquid is sprayed to tooth part to form a tooth part quench hardened layer 2. At this time, rack part is not locally deformed and tooth part is convexly bent in axial line direction. The rack 1 is fixed with electrodes 13, 14, etc., while almost parallelly setting tooth edge surface to plane surface of an induction coil 19 having almost plane surface and opposing the coil 19 to rear part, rear part is heated under a prescribed condition, then coolant liquid is injected thereto to form a rear part quench hardened layer 3. At this time, rack tooth is not locally deformed, tooth part is concavely bent in axial line direction by heat treatment stress, the former bending of the layer 2 during quenching is regulated and correcting operation can be facilitated.</p> |
