A forging apparatus includes an ironing mechanism and a phase alignment mechanism. The ironing mechanism includes: a punch set, which is fitted into a cylindrical portion of a pre-processing material to be formed into the outer joint member, and is radially expandable and contractible, the cylindrical portion having grooves formed in an inner peripheral surface thereof; and a die having a hole into which the cylindrical portion is press-fitted. The phase alignment mechanism is configured to align phases of the grooves in the inner peripheral surface of the pre-processing material and phases of track groove portion forming surfaces of the punch set with each other before the pre-processing material is fitted to the punch set.

Outer ball grooves of an outer joint member of a constant velocity joint each have a first ball groove for allowing a ball to roll therein when the constant velocity joint operates, and a second ball groove having a ball groove radius larger than a ball groove radius of the first ball groove. The second ball groove has a curved line and a connecting line. The curved line is connected to a groove bottom end of the first ball groove located closer to an opening of the outer joint member and is curved radially outward in a concave manner. The connecting line connects the curved line and the opening. The curved line is curved with a curvature center that is located closer to the opening than the groove bottom end of the first ball groove and that is located radially inside the outer joint member.

A method for manufacturing a rolling bearing unit is provided to periodically reciprocate a stage (38) in a vertical direction by rotating and driving a servo motor (44) while rotating a roll about a central axis of a hub main body using a roll driving motor (43) in a state in which a processing surface of the roll is pressed against other end surface of a caulking section in an axial direction. A period of the reciprocation is restricted by a relation between a rotation position of the roll about the central axis of the hub main body and an engaged state between concave sections, which are sections between a plurality of processed teeth formed in the processing surface of the roll, and a face spline tooth formed by the concave section.

A manufacturing method is used for an outer joint member of a constant velocity universal joint. The outer joint member includes a cup section having track grooves formed in its inner periphery, which are engageable with torque transmitting elements, and a shaft section formed at a bottom portion of the cup section. The manufacturing method includes welding the cup and shaft members by irradiating a beam to joining end portions of the cup and shaft members, causing an outer surface including the welded portion to be formed into a flat smooth surface by removal processing, irradiating ultrasonic waves to the flat smooth surface with one probe at an incident angle which prevents total reflection in a circumferential angle beam flaw detection method, and setting a focal point of the ultrasonic waves to positions from a surface to an inside of the welded portion, to thereby perform inspection.

A manufacturing method is used for an outer joint member of a constant velocity universal joint. The outer joint member includes a cup section having track grooves formed in an inner periphery of the cup section, which are engageable with torque transmitting elements, and a shaft section formed at a bottom portion of the cup section. The outer joint member is constructed by forming the cup section and the shaft section as separate members, and by welding a cup member forming the cup section and a shaft member forming the shaft section to each other. The manufacturing method at least includes welding the cup member and the shaft member by irradiating a beam to joining end portions of the cup member and the shaft member, and inspecting a welded portion formed in the welding by a plurality of ultrasonic flaw detection methods with one probe.

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.

A rotary press device (33) includes a restriction section (36) configured to restrict a motion of a roll (30) around a central axis of a roll (30) against movement of the roll (30) around a central axis of a hub main body (8) during rotary forging. In an example, the restriction section (36) has guide teeth (44) meshed with teeth formed on a processing surface of the roll (30).

A rotary press device (33) includes a restriction section (36) configured to restrict a motion of a roll (30) around a central axis of a roll (30) against movement of the roll (30) around a central axis of a hub main body (8) during rotary forging. In an example, the restriction section (36) has guide teeth (44) meshed with teeth formed on a processing surface of the roll (30).

The present invention relates to a method for manufacturing a universal joint using a pipe. The shaft joint of the universal joint is manufactured by: a material preparation step of preparing a material by cutting a pipe to a predetermined length; a shaft formation step of forming a shaft by reducing the outer diameter of a shaft formation portion by forming the outside of the shaft formation portion with a forming machine; a cutting step of bisecting the non-reduced head formation portion by forming a split across the non-reduced head formation portion in an axial direction; a yoke formation step of forming both opposite members of a yoke in a head by pressing the bisected head formation portion; a pinhole formation step of forming a pinhole across the yoke; and a spline shaft formation step of forming a spline shaft on the outer surface of the reduced hollow shaft.

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.