Abstract: In a method for producing a motor rotor, a lamination stack made up of stacked thin steel sheets each formed with a through hole, the lamination stack having a shaft bore formed of the through holes aligned with one another, is retained as a rotor core in a thickness direction with a pair of jigs from both sides, and a shaft is inserted into the shaft bore and joined to the lamination stack by shrink fitting. Each jig includes a shaft hole, a radially inner peripheral portion for holding a peripheral edge of the shaft bore of the lamination stack at a position, in a radial direction of the shaft hole, surrounding the shaft hole radially inside; and a radially outer peripheral portion for holding the outer periphery of the lamination stack. The radially inner and outer peripheral portions are positioned at different heights in a jig height direction.

Abstract: In a method for producing a motor rotor, a lamination stack made up of stacked thin steel sheets each formed with a through hole, the lamination stack having a shaft bore formed of the through holes aligned with one another, is retained as a rotor core in a thickness direction with a pair of jigs from both sides, and a shaft is inserted into the shaft bore and joined to the lamination stack by shrink fitting. Each jig includes a shaft hole, a radially inner peripheral portion for holding a peripheral edge of the shaft bore of the lamination stack at a position, in a radial direction of the shaft hole, surrounding the shaft hole radially inside; and a radially outer peripheral portion for holding the outer periphery of the lamination stack. The radially inner and outer peripheral portions are positioned at different heights in a jig height direction.

Abstract: A thread rolling apparatus has thread rolling dies mounted respectively on a pair of sliding mechanisms which are vertically movably driven by respective actuators, and a support disposed between the thread rolling dies for rotatably supporting a workpiece. The sliding mechanisms and the support are interconnected by a rack and pinion mechanism for imparting a forced rotational drive force to the workpiece in synchronism with the movement of the sliders. The lead angle of the thread rolling dies is set to match the forced rolling diameter of the workpiece. By adjusting the distance between the thread rolling dies in matching relation to the workpiece diameter before threading, the thread rolling apparatus can form different screws having equal pitches and different nominal diameters.

Abstract: Serration rolling tools and thread rolling tools each having groups of leading teeth, finishing teeth and disengaging teeth are provided, a lead angle of the thread rolling tool being set in accordance with the rolling diameter of the serration section in a work piece. The thread rolling tool and serration rolling tool are arranged parallel and integrally. First a rolling operation for forming serrations is started by the serration rolling tools, a rolling operation for forming threads being started by the thread rolling tools in the course of the rolling operation by the group of the leading teeth of the serration rolling tools. A rolling operation for finishing the threads is completed in the latter half of the rolling operation by the group of the finishing teeth for the serrations. The difference in rolling diameters is absorbed by the slide of the aforesaid thread rolling tools on a shaft member (work piece), thus enabling the simultaneous formation of serrations and threads in a short rolling stroke.

Abstract: A method of making valve sleeves used for controlling the flow of hydraulic fluid in devices, such as power steering units in motorized vehicle, and the product of the utilized method. The method utilizes a grooving male die which forms a groove on an interior surface of a valve sleeve.

Abstract: A forced rotational drive force is imparted to a workpiece in synchronism with the movement of a pair of thread rolling dies, the thread rolling dies having a lead angle selected to match the forced rolling diameter of the workpiece, for thereby forming screw threads on the workpiece. These thread rolling dies are moved toward each other to form screw threads on a workpiece. By adjusting the distance between the thread rolling dies to match the workpiece diameter before threading, there can be produced various screws having equal pitches and different nominal diameters.