Patent ID: 8353778

Claim:
A tripod type constant velocity universal joint comprising: an outer joint member having an inner peripheral surface provided with three linear track grooves extending in an axial direction; a tripod member arranged in the outer joint member and including a boss portion and three leg shafts protruding from a radially outer surface of the boss portion; and a plurality of torque transmitting elements supported respectively by the three leg shafts and guided respectively by the three linear track grooves, the tripod member being molded with a full-enclosed forging die including a plurality of openable/closable dies and a plurality of punches for pressing a material between the openable/closable dies, wherein the radially outer surface of the boss portion of the tripod member comprises, from an axial central portion to each of opposite end surfaces, a first flat-surface portion, a convex curved-surface portion, a tapered-surface portion, a concave curved-surface portion, and a second flat-surface portion, the tapered-surface portion being tangential with respect to the convex curved-surface portion, a taper angle of the tapered-surface portion being set to 25° or less, the tapered-surface portion being tangential with respect to the concave curved-surface portion, the first flat-surface portion being tangential with respect to the convex curved-surface portion and being parallel to an axial direction, and the second flat-surface portion being tangential with respect to the concave curved-surface portion and being parallel to the axial direction, and wherein a projection area of an entire periphery in a peripheral direction of a projection portion of the radially outer surface of the boss portion on a plane including either of the opposite end surfaces of the boss portion is smaller than if the radially outer surface was formed as a single convex curved surface about a boss-portion axial center.