A method for producing a joint outer part by means of flow forming is provided. A blank is arranged on a contour mandrel such that it cannot rotate with respect to the contour mandrel. The contour mandrel is driven in such a way that the blank and the contour mandrel rotate about a common axis. The blank is shaped at least partially with the aid of a flow forming roller which acts on the blank in order to form the joint outer part. At least one track is formed with a concave region in the joint outer part.

A double-offset plunging type constant velocity universal joint includes inner and outer joint members each having six linear track grooves extending along an axial direction. The inner joint member has a coupling hole at a center portion thereof for coupling a shaft. Six torque transmission balls retained by a cage are incorporated between the linear track grooves of the inner and outer joint members. A ratio T.sub.CAGE/D.sub.BALL of a minimum thickness (T.sub.CAGE) of the cage to a diameter of the torque transmission ball (D.sub.BALL) is from 0.225 to 0.245, wherein a ratio D.sub.BALL/D.sub.S of a diameter (D.sub.BALL) of the torque transmission ball to a spline large diameter (D.sub.S) of the coupling hole of the inner joint member is from 0.79 to 0.85, and wherein a ball contact ratio () of the torque transmission ball is from 1.08 to 1.12.

Machining ball tracks and guiding webs of an inner part for a constant velocity joint in a clamping arrangement includes mechanical machining of at least one first ball track in a first rotational position; rotating the articulated inner part into a second rotational position for machining at least one further ball track; wherein at least one guiding web is mechanically machined during the rotating of the inner joint part from the first rotational position into the second rotational position. A corresponding device is used for machining ball tracks and guiding webs of an inner joint part.

A fixed type constant velocity universal joint (3) includes an outer joint member (31), an inner joint member (32), eight balls (33), and a cage (34). A curvature center (O.sub.31d) of track grooves (31d) of the outer joint member (31) and a curvature center (O.sub.32e) of track grooves (32e) of the inner joint member (32) are offset to opposite sides in an axial direction of the joint with respect to a joint center (O(f)) by an equal distance. A ratio (PCD.sub.BALL/D.sub.BALL) of a pitch circle diameter (PCD.sub.BALL) of the balls (33) to a diameter (D.sub.BALL) of each of the balls (33) is set from 3.70 to 3.87. A ratio (T.sub.C/D.sub.BALL) of a radial thickness (T.sub.C) of the cage (34) to the diameter (D.sub.BALL) of each of the balls (33) is set from 0.22 to 0.25.

A fixed type constant velocity universal joint (3) includes an outer joint member (31), an inner joint member (32), eight balls (33), and a cage (34). A diameter (D.sub.31c) of the outer joint member (31) at an opening end of an inner peripheral surface (31c) is set larger than an outer diameter (D.sub.34b) of the cage (34) at a center portion in a circumferential direction of pockets (34a) when the cage (34) is seen from an axial direction of the joint. A bottom surface (31f) of a mouth section (31a) of the outer joint member (31) is arranged so as to interfere with an imaginary spherical surface (Q) being an extension of the inner peripheral surface (31c) of the outer joint member (31) toward a deep-side.

There is provided a sliding constant velocity universal joint (3) which allows consistent placement of a coil spring (21) at a predetermined position, visible check into the state of assembly from an external view, and therefore has reduced chances for buckling/deformation of the coil spring (21) and has stable sliding characteristics. In a sliding constant velocity universal joint configured for torque transmission while allowing an angle change and an axial change, an outer joint member (4) incorporates therein an elastic member (21) axially expandable/retractable between a tip of a shaft (1) connected to an inner joint member (5) and the outer joint member (4); the tip of the shaft (1) is provided with a shaft protruding portion (27) for supporting an inner diameter portion of an end portion of the elastic member (21) facing the shaft (1); the elastic member (21) has its end facing the outer-joint-member (4) provided with a receptacle (24) for fitting into an inner diameter portion of the elastic member (21); the outer joint member (4) has its inner surface press-fitted by an end plate (23); and the receptacle (24) is pressed onto the end plate (23) in the inner surface of the outer joint member (4).

A counter track joint comprises an outer joint part, an inner joint part, first pairs of tracks widening towards the opening side of the outer joint part when the counter track joint is aligned, and second pairs of tracks widening towards the connecting side of the outer joint part when the counter track joint is aligned; a ball in each of the first and second pairs of tracks; a ball cage having circumferentially distributed cage windows each receiving one of the balls, wherein one of the outer ball track group and the inner ball track group is hardened and hard machined, and the other of the outer ball track group and the inner ball track group is soft finished and subsequently hardened. A method of manufacturing a counter track joint is provided.

A tripod constant-velocity joint includes: an outer joint member having a cavity elongated in a longitudinal direction and three roller tracks; an inner joint member having a center body and three journals outwardly radially protruded from the center body; and three roller assemblies respectively coupled to the journal in a state of being respectively disposed in the roller tracks. The respective roller assembly comprises: an inner race which is connected to the journal and is provided with a first inner ball groove and a second inner ball groove on both lateral sides thereof; a first ball array and a second ball array respectively having a plurality of balls which are respectively disposed in the first inner ball groove and in the second inner ball groove; and a ball cage which restricts movements of the first ball array and the second ball array in a longitudinal direction thereof.

A fixed type constant velocity universal joint has an operation mode in which, when a maximum operating angle is taken, in a column portion that is one of column portions on both sides of a pocket of a cage receiving a torque transmission ball at a phase angle and is located on a side corresponding to a phase angle larger than the phase angle, a projection end portion obtained by projecting an end portion of a spherical inner peripheral surface of the outer joint member on the opening side in a perpendicular direction toward the spherical outer peripheral surface of the cage and a projection end portion obtained by projecting an end portion of the spherical outer peripheral surface of the inner joint member on the back side in the perpendicular direction toward the spherical inner peripheral surface of the cage overlap in the axial direction of the cage.

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.