| 摘要 |
PROBLEM TO BE SOLVED: To provide a method for quenching rack teeth so as not to cause quenching failure originating in insufficient heating in the vicinity of the rack teeth in an end of a rack shaft, using a direct energization heating and quenching method. SOLUTION: A leading edge 15a of a first electrode 15 is formed into such a shape as to be engaged and contact with rack teeth 11a of a rack shaft 11, and a second electrode 17 is structured into such a shape as to be pressure-welded to an inner bottom surface 11h of a tie-rod-fixing hole 11g in the end of the rack shaft in the shaft direction. The quenching method comprises the steps of: actuating hydraulic organizations 12 and 13 arranged in the opposite sides across the rack shaft 11; bringing the rack teeth 11a1 in one end of the rack shaft 11 in contact with the leading edge of the first electrode 15; pressure-welding the leading edge 17a of the second electrode 17 to the inner bottom surface 11h of the tie-rod-fixing hole in the other end of the rack shaft 11; and supplying a high-frequency electric current between the electrodes through the rack shaft 11 from a high-frequency power source 11. Because the second electrode 17 does not contact with the rack teeth 11a2 in the end, the rack teeth in the end is sufficiently heated as well. Accordingly, the quenching failure does not occur. COPYRIGHT: (C)2007,JPO&INPIT
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