Abstract: A steel workpiece maintained at a specified quenching temperature is rapidly cooled to a temperature just above the martensite transformation start point (Ms point) by being immersed in a high-temperature quenching oil. Thereafter, the steel workpiece is taken out of the high-temperature quenching oil so as to be soaked by the heat possessed by the steel workpiece and subsequently cooled by being immersed in the high-temperature quenching oil. Through these processes, a temperature difference between steel workpieces or the portions of a steel workpiece in the martensite transformation stage is reduced, and a cooling speed in a high-temperature region (not lower than about 550° C.) is made to be a slow speed sufficient for restraining a thermal distortion, by which the quenching distortion and quenching variation can be reduced.

Abstract: A steel workpiece maintained at a specified quenching temperature is rapidly cooled to a temperature just above the martensite transformation start point (Ms point) by being immersed in a high-temperature quenching oil. Thereafter, the steel workpiece is taken out of the high-temperature quenching oil so as to be soaked by the heat possessed by the steel workpiece and subsequently cooled by being immersed in the high-temperature quenching oil. Through these processes, a temperature difference between steel workpieces or the portions of a steel workpiece in the martensite transformation stage is reduced, and a cooling speed in a high-temperature region (not lower than about 550° C.) is made to be a slow speed sufficient for restraining a thermal distortion, by which the quenching distortion and quenching variation can be reduced.

Abstract: A parts feeder for feeding parts that are disposed on a carrier having a base tape and an adhesive tape. Parts are disposed above holes which are formed at equal intervals on the base tape, and the parts are held by an adhesive tape adhered to a lower surface of the base tape. The feeder includes a pitched feeding mechanism for intermittently feeding the carrier tape at a predetermined pitch, a separating mechanism for separating the adhesive tape from the base tape in synchronization with the feeding of the carrier tape at an adhesive tape separating stage, and a pressing mechanism for pressing the parts disposed on the base tape against the base tape prior to the separation of the adhesive tape from the base tape at the adhesive tape separating stage.