Abstract: A tripod type constant velocity universal joint includes an outer joint member having track grooves formed at trisected positions in a circumferential direction to extend in an axial direction thereof, and a tripod member. The tripod member includes a trunnion barrel and trunnion journals radially projecting from trisected positions on the trunnion barrel in the circumferential direction. The universal joint also includes spherical rollers each fitted in a rotatable manner about each of the trunnion journals through intermediation of a plurality of needle rollers. The spherical rollers are in the track grooves, and each has an outer spherical surface guided by roller guide surfaces formed on both side walls of each of the track grooves. Hollow holes are formed in the trunnion journals, respectively, and a quench-hardened layer is formed on each of outer circumferential surfaces of the trunnion journals and surfaces of the hollow holes.

Abstract: A tripod type constant velocity universal joint has an inner circumferential surface of each inner ring which is configured to rotatably support a roller formed to have an arc-shaped protruding section, and an outer circumferential surface of each leg shaft of a tripod member formed to have a straight shape in longitudinal section and a substantially elliptical shape in transverse section. The outer circumferential surface of the leg shaft and the inner circumferential surface of the inner ring are held in contact with each other in a direction orthogonal to an axis of the joint and have a gap between the outer circumferential surface and the inner circumferential surface in an axis direction of the joint. The leg shaft has a hollow hole in which a quench-hardened layer is formed on the outer circumferential surface of the leg shaft and a surface of the hollow hole.

Abstract: A forging method for a shaft member includes preforming at least one of a plurality of enlarged diameter portions to obtain a semi-finished member, and forming a remainder of the enlarged diameter portions in the semi-finished member using a mold. The mold includes a punch, split dies, and a workpiece receiving member. The forming of the remainder of the enlarged diameter portions includes allowing the semi-finished member having the at least one of the enlarged diameter portions to be placed on the workpiece receiving member, cramping the semi-finished member in its radial direction by closing the split dies, and filling the semi-finished member into forming surfaces of the split dies by the pressure applied by the punch under the state in which the semi-finished member is cramped.

Abstract: Provided is a tripod type constant velocity universal joint, including: an outer joint member having track grooves; a tripod member including trunnion journals; and spherical rollers each fitted in a rotatable manner about each of the trunnion journals through intermediation of a plurality of needle rollers, in which a corner portion is formed at a root portion of the each of the trunnion journals so as to restrict movement of each of the plurality of needle rollers in the axial direction toward the root portion of the each of the trunnion journals by interference between an end surface corner rounded portion of the each of the plurality of needle rollers and the corner portion at the root portion.

Abstract: An inspection device inspects a joint-type outer joint member of a constant velocity universal joint that includes a cup section having a bottomed cylindrical shape and track grooves in an inner periphery thereof for torque transmitting elements, and a shaft section extending from a bottom of the cup section. The inspection device inspects the outer joint member, which is obtained through melt-welding on a cup member forming the cup section and a shaft member forming the shaft section. The inspection device includes a surface inspection unit to inspect for a defect which appears on a surface of the outer joint member due to welding, an internal inspection unit to inspect for an internal defect of a welded portion, and a recording unit to record an inspection result of the inspection. The inspection device is configured to efficiently perform in-line total inspection for the melt-welded joint-type outer joint member.

Abstract: Provided is a method of manufacturing an outer joint member of a constant velocity universal joint, which is constructed by forming a cup section having track grooves, and a shaft section, and by welding a cup member and a shaft member, the method including: forming the cup member and the shaft member of medium carbon steel; preparing a cup member having a cylindrical portion and a bottom portion integrally formed by forging, and a joining end surface in a machining step; preparing a shaft member having a joining end surface formed in a machining step; bringing the joining end surface of the cup member and the joining end surface of the shaft member into abutment against each other; welding the cup member and the shaft member by radiating a beam; and performing, after the welding, an ultrasonic flaw detection-inspection step.

Abstract: In an outer joint member of a constant velocity universal joint, a cup member and a shaft member are made of medium to high carbon steel and welded together. The cup member has a bottomed cylindrical shape that is opened at one end, and includes a cylindrical portion, a bottom portion, and a short shaft section of a solid shaft shape protruding from the bottom portion and having a joining end surface. The shaft member has a solid shaft shape and a joining end surface. The joining end surfaces of the cup and shaft members are brought into abutment against each other, and a high energy intensity beam is radiated from an outer side in a radial direction to form a welded portion. A structure of a molten metal at the welded portion is in a mixed phase of ferrite and granular cementite.

Abstract: In a tripod type constant velocity universal joint 1, when D1 represents a large inner diameter being a diameter of a circle connecting radially outer end portions of roller guide surfaces 7 and D2 represents a small inner diameter being a diameter of a circle connecting radially inner end portions of the roller guide surfaces 7, a ratio D2/D1 between the small inner diameter D2 and the large inner diameter D1 is set within a range of from 0.73 to 0.80. Further, when d represents a large diameter of a spline formed in a trunnion hub 8 of a tripod member 3 and PCD represents a pitch circle diameter of the roller guide surfaces 7, a ratio d/PCD between the large diameter d and the pitch circle diameter PCD is set to 0.60 or more.

Abstract: A cup member has a cylindrical portion, a bottom portion, and a short shaft portion having a solid shaft shape and including a joining end surface at an end portion thereof. A shaft member has a solid shaft shape and includes a joining end surface at one end thereof. The joining end surfaces of the cup and shaft members are brought into abutment against each other and welded from a radially outer side to form a welded portion. At this time, center segregation is prevented from interfering with the welded portion. The cup member is formed by forging including upsetting a billet having a columnar shape successively in a plurality of stages, extruding the cylindrical portion and the short shaft portion, and ironing the cylindrical portion. In the course of the upsetting, a region of the billet corresponding to a bottom side of the cup member is narrowed.

Abstract: A method of manufacturing an outer joint member of a constant velocity universal joint includes forming cup and shaft members of medium carbon steel, preparing, as the cup member, a cup member having cylindrical and bottom portions integrally formed by forging, and a joining end surface formed on an outer surface of the bottom portion, and preparing, as the shaft member, a shaft member having a joining end surface to be joined to the bottom portion of the cup member. The method also includes bringing the joining end surfaces of the cup and shaft members into abutment against each other, and welding the cup and shaft members from an outer side of the cup member to an abutment portion between the cup and shaft members in a radial direction of the cup members.

Abstract: A method of manufacturing an outer joint member of a constant velocity universal joint includes forming cup and shaft members using medium carbon steel, preparing, as the cup member, a cup member having cylindrical and bottom portions integrally formed, and a joining end surface formed on an outer surface of the bottom portion, preparing, as the shaft member, a shaft member having a joining end surface to be joined to the bottom portion of the cup member, and bringing the joining end surfaces of the cup and shaft members into abutment against each other. The method also includes welding the cup and shaft members from an outer side of the cup member to an abutment portion between the cup and shaft members in a radial direction of the cup member under a state in which a hollow cavity portion is formed inside the abutment portion.

Abstract: A method of manufacturing an outer joint member of a constant velocity universal includes forming cup and shaft members of medium carbon steel, preparing, as the cup member, a cup member having cylindrical and bottom portions integrally formed by forging, and a joining end surface formed on an outer surface of the bottom portion after the forging, preparing, as the shaft member, a shaft member having a joining end surface to be joined to the bottom portion of the cup member, and bringing the joining end surfaces of the cup and shaft members into abutment against each other. The method also includes welding the cup and shaft members from an outer side of the cup member to an abutment portion between the cup and shaft members in a radial direction of the cup member.

Abstract: For butt-welding, which includes bringing joining end surfaces of a cup member and a shaft member into abutment against each other and radiating a high energy intensity beam from a radially outer side, the shaft member has a recess on a radially inner side of the joining end surface to obtain a welded portion having a closed hollow cavity on a radially inner side after butt-welding. The joining end surface (protruding surface) of the cup member protrudes toward a radially inner side with respect to an inner diameter of the joining end surface of the shaft member. With this, a welded portion of an outer joint member of a constant velocity universal joint, which is manufactured by joining the cup member and the shaft member, can be improved in strength and quality.

Abstract: A method of manufacturing an outer joint member of a constant velocity universal joint includes forming cup and shaft members of medium carbon steel, forging the cup member to have integrally formed cylindrical and bottom portions, and machining a joining end surface on an outer surface of the bottom portion after the forging. The method also includes preparing the shaft member to have a joining end surface to be joined to the bottom portion of the cup member, which is formed by machining, bringing the joining end surfaces of the cup and shaft members into abutment against each other and welding the cup and shaft members by radiating a beam from an outer side of the cup member to an abutment portion between the cup and shaft members in a radial direction of the cup member.

Abstract: Provided is a method of manufacturing an outer joint member of a constant velocity universal joint, which is constructed by welding a cup member and a shaft member, the method including: forming the cup member and the shaft member of medium carbon steel; preparing; preparing; bringing the joining end surface of the cup member and the joining end surface of the shaft member into abutment against each other; welding the cup member and the shaft member; and performing, after the welding, ultrasonic flaw detection-inspection from any one of a surface side of the cup member and a surface side of the shaft member, which has the another one of the joining end surface of the cup member and the joining end surface of the shaft member.

Abstract: A method of manufacturing an outer joint member of a constant velocity universal joint includes forming cup and shaft members of medium carbon steel, forging the cup member to have integrally formed cylindrical and bottom portions, and machining a joining end surface on an outer surface of the bottom portion after the forging. The method also includes preparing the shaft member to have a joining end surface to be joined to the bottom portion of the cup member, which is formed by machining, bringing the joining end surfaces of the cup and shaft members into abutment against each other and welding the cup and shaft members by radiating a beam from an outer side of the cup member to an abutment portion between the cup and shaft members in a radial direction of the cup member.

Abstract: A constant-velocity universal joint includes an outer joint member; an inner joint member arranged in an inside of the outer joint member; and torque transmitting members. At least one of the outer joint member and the inner joint member comprises track grooves that are engaged with rolling surfaces of the torque transmitting members. At least one of the components of the constant-velocity universal joint is formed of a metal sintered compact. The metal sintered compact has a relative density of 80% or more and less than 100%. The metal sintered compact comprises a hardened layer formed on a surface thereof through heat treatment. Among the components each formed of the metal sintered compact, a component having a ring shape is subjected to a cold rolling process.