PRECISE HEAT-TREATMENT OF THIN HOLLOW CYLINDRICAL BODY, APPARATUS THEREFOR, AND PRECISELY HEAT-TREATED THIN HOLLOW CYLINDRICAL BODY OBTAINED THEREBY

摘要

PURPOSE:To precisely heat-treat the whole thickness of a hollow cylindrical body without substantial generation of bending strain, by heat-treating the hollow cylindrical body under the condition that its end surface is supported by pressing force expansible with respect to thermal affection and that binding power in point-to-point cotact is applied to the cylindrical body along its circumferential direction. CONSTITUTION:A thin hollow cylindrical body W is clamped between clamping rotary means 5a and 5b against a coil spring 52, forcedly rotated and dislocated to a heating zone H. The cylindrical body W is circumscribed to a roll 6 by a slight contact surface at its outside points, and induction-heated. An expanding phenomenum at this time is restricted by the roll 6, and axially expanded so as to contract the coil spring 52. consequently, the expanding length is absorbed. When the quenched cylindrical body W is dislocated to a cooling zone Q, the expansion formed during heating is shrunk. At this time, the cylindrical body W is restricted by the point-to-point contact of the roll 6, so that the cylindrical body W, being axially constricted by the pressing power of the coil spring 52, is cooled. In this way, the whole length of the heated part is uniformly cooled.