Abstract: A steel component formed by carburizing and then induction-hardening of a steel consisting essentially of, by mass, C: minimum 0.08% and less than 0.3%; Si: maximum 2.0%; Mn: from 0.2% to 3.0%; P: maximum 0.03%; S: from 0.005% to 0.05%; Ni: maximum 1.5%; Cr: maximum 3.0%; Mo: maximum 1.0%; O: maximum 0.0025%; and N: from 0.005% to 0.03%; and further including either or both of, by mass, Al: from 0.005% to 0.05%, and Ti: from 0.005% to 0.05%; and still further including either or both of, by mass, V: maximum 0.3%, and Nb: maximum 0.3%; and a balance including Fe and unavoidable impurities. The hardness of the surface layer is at least 55 HRC and the hardness of the core portion is from 20 to 50 HRC. The core portion does not include a martensite structure.

Abstract: A method of heat-treating a steel member including carburizing a steel member in a carburizing gas under a reduced pressure. The steel member is then cooled in a cooling gas having a pressure lower than atmospheric pressure. A desired portion of the cooled steel member is then heated using high-density energy. The steel member is then quenched.

Abstract: A steel component formed by carburizing and then induction-hardening of a steel consisting essentially of, by mass, C: minimum 0.08% and less than 0.3%; Si: maximum 2.0%; Mn: from 0.2% to 3.0%; P: maximum 0.03%; S: from 0.005% to 0.05%; Ni: maximum 1.5%; Cr: maximum 3.0%; Mo: maximum 1.0%; O: maximum 0.0025%; and N: from 0.005% to 0.03%; and further including either or both of, by mass, Al: from 0.005% to 0.05%, and Ti: from 0.005% to 0.05%; and still further including either or both of, by mass, V: maximum 0.3%, and Nb: maximum 0.3%; and a balance including Fe and unavoidable impurities. The hardness of the surface layer is at least 55 HRC and the hardness of the core portion is from 20 to 50 HRC. The core portion does not include a martensite structure.

Abstract: A method of heat-treating a steel member including carburizing a steel member in a carburizing gas under a reduced pressure. The steel member is then cooled in a cooling gas having a pressure lower than atmospheric pressure. A desired portion of the cooled steel member is then heated using high-density energy. The steel member is then quenched.

Abstract: A Roots pump having a plurality of rotor assemblies each including a light-alloy rotor, a steel shaft press-fitted in a bore of the rotor and a lock pin which is inserted through the rotor and the shaft to prevent removal of the shaft from the rotor. The lock pin is located substantially at an axial center of a press-fitted portion of the shaft accommodated the axial bore. The shaft has a timing gear at one end thereof for meshing with a timing gear of the shaft of the adjacent rotor assembly. The shaft further has a plurality of engagement teeth provided at one of opposite ends of the press-fitted portion on the side of the timing gear. The engagement teeth are at least partially embedded in an inner surface defining the axial bore of the rotor, upon press-fitting of the press-fitted portion in the axis bore, to thereby prevent a rotational movement of the shaft relative to the rotor.

Abstract: A solenoid valve for hydraulic control, comprises: a stationary iron core; a guide pipe; a return spring; a plunger; and a valve body.Firstly, the plunger is made slidable immediately on the inner periphery of a columnar recess of the stationary iron core, whereby a magnetic reluctance of a magnetic path formed when a current is passed is decreased, so that an attracting force can be increased accordingly.Furthermore, the plunger made hollow is made slidable on the outer periphery of the guide pipe and the valve body is fixed to and disposed at an end portion of the plunger, so that these movable members can be rendered light in weight.Further, a member for guiding the sliding of the plunger (a guide pipe) is disposed on the inner periphery of the plunger made hollow, further, this guide member is made hollow, and a return spring is incorporated in this guide member, so that the solenoid valve as a whole can be rendered very compact.

Abstract: Herein disclosed are outer race working method and apparatus of the type, in which such a roughly shaped outer race workpiece of a Birfield type constant-velocity ball joint as is formed with a groove made axially straight at its portion above the joint center and having an axial curvature below the joint center, in which a hexagonal-pillar guide punch and a split mandrel composed of six segments are inserted into the aforementioned groove of the roughly shaped workpiece thereby to iron the inner surface of the aforementioned groove and to form both a center hole corresponding to the center of a ball rolling groove and a face for providing a reference for the axial position of the groove center, and in which the roughly shaped workpiece is then ironed by means of an ironing die, whereby the ball rolling groove is plastically worked all over its surface from its lower portion to its upper portion.