A shaft coupling structure of the present invention includes a male joint and a female shaft that are coupled together. The outer peripheral surface of the male joint has an outer peripheral side concave-convex portion having a concave-convex shape in the circumferential direction and an annular concave groove, and the inner peripheral surface of the female shaft has an inner peripheral side concave-convex portion having a concave-convex shape in the circumferential direction. The outer peripheral side concave-convex portion and the inner peripheral side concave-convex portion engage with a concave-convex engagement. The outer peripheral surface of the male joint and an end portion on one side of the female shaft in the axial direction are welded and fixed together, and an embossed portion provided on the inner peripheral surface of the female shaft is arranged on the inner side of the annular concave groove.

A shaft coupling structure of the present invention includes a male joint and a female shaft that are coupled together. The outer peripheral surface of the male joint has an outer peripheral side concave-convex portion having a concave-convex shape in the circumferential direction and an annular concave groove, and the inner peripheral surface of the female shaft has an inner peripheral side concave-convex portion having a concave-convex shape in the circumferential direction. The outer peripheral side concave-convex portion and the inner peripheral side concave-convex portion engage with a concave-convex engagement. The outer peripheral surface of the male joint and an end portion on one side of the female shaft in the axial direction are welded and fixed together, and an embossed portion provided on the inner peripheral surface of the female shaft is arranged on the inner side of the annular concave groove.

Provided is a power transmission shaft, including: a metal shaft member; and a resin shaft member connected to the metal shaft member in an axial direction of the power transmission shaft. The resin shaft member is made of fiber reinforced plastic. The metal shaft member and the resin shaft member are joined to each other through a close-contact fitting portion between a male spline, which is formed in an outer surface of the metal shaft member, and a female spline formed by press-fitting the male spline into the resin shaft member. An edge is formed at a radially outer edge portion of a press-fitting-start end surface of the male spline of the metal shaft member.

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.

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.

An outer joint member of a constant velocity universal joint includes a cup section having track grooves formed in an inner periphery thereof, which are engageable with torque transmitting elements, and a shaft section formed at a bottom portion of the cup section. The cup section and the shaft section are formed as separate members, and by bringing a cup member forming the cup section and a shaft member forming the shaft section into abutment against each other at respective joining end surfaces and welding them, a hollow cavity portion is formed. The cup member has, at an axial center, a ventilation hole that communicates with the hollow cavity portion and any one of the joining end surfaces of the cup member and the joining end surface of the shaft member has a welding spatter receiving groove formed on a radially inner side thereof.

An outer joint member of a constant velocity universal joint includes a cup section having track grooves formed in an inner periphery thereof, which are engageable with torque transmitting elements, and a shaft section formed at a bottom portion of the cup section. The cup section and the shaft section are formed as separate members, and by bringing a cup member forming the cup section and a shaft member forming the shaft section into abutment against each other at respective joining end surfaces and welding them, a hollow cavity portion is formed. The cup member has, at an axial center, a ventilation hole that communicates with the hollow cavity portion and any one of the joining end surfaces of the cup member and the joining end surface of the shaft member has a welding spatter receiving groove formed on a radially inner side thereof.

A vehicular propeller shaft through which a rotary motion of a drive power source is transmitted to drive wheels and which includes a first tubular member and a second tubular member. The first tubular member has a large-diameter cylindrical section, a small-diameter cylindrical section having a smaller outside diameter than the large-diameter cylindrical section, and a tapered cylindrical section formed between one end of the large-diameter cylindrical section and the small-diameter cylindrical section. The large-diameter cylindrical section, the small-diameter cylindrical section and the tapered cylindrical section are formed integrally with each other. The second tubular member is coaxially joined to the first tubular member and formed of a material having a higher degree of strength than the first tubular member.

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.

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.