Ntn Corporation

Shunsuke Makino

Jiahua Miao

Akira Sera

Hiroshi Murakami

Hiroshi Adachi

Junichi Izumino

Taku Itagaki

Kenji Konaka

Makoto Ikki

A tripod type constant velocity universal joint includes an outer joint member including three track grooves having roller-guide surfaces arranged to face each other in a circumferential direction, a tripod member including three leg shafts projecting in a radial direction, and roller units each including a roller and an inner ring for supporting the roller in a freely rotatable manner. The inner ring is externally fitted to a corresponding one of the three leg shafts. The roller is movable along the roller-guide surfaces of a corresponding one of the three track grooves. Each of the three leg shafts includes a region formed into a substantially circular-arc shape in horizontal cross-section that is orthogonal to an axial line of each of the three leg shafts.

Tripod type constant velocity universal joint and method for producing same

After molding a preliminarily molded product as a material, the preliminarily molded product is put into a full-enclosed forging die so that a product is molded with the full-enclosed forging die. A shear-drop suppressing portion for suppressing thickness reduction on a boss-portion side of an outer peripheral portion of a leading end surface of each of shaft portions of the product is formed on the preliminary leading-end surface configuring a leading end surface of each of the shaft portions of the product in the preliminarily molded product. When the preliminarily molded product is put into the full-enclosed forging die and the product is to be molded, a relief portion is formed between the leading end surface of each of the shaft portions to be molded and a cavity of the full-enclosed forging die.

Forging method, molding device for forgings, and tripod uniform motion universal joint

After molding a product-to-be-preliminarily-molded to form a preliminarily molded product as a material, the preliminarily molded product is put into a full-enclosed forging die so that a product is molded with the full-enclosed forging die. On a preliminary leading-end surface to be formed as a leading end surface of a shaft portion of the product formed of the preliminarily molded product, there is formed a shear-drop suppressing portion for suppressing thickness reduction on a boss-portion side of an outer peripheral portion of the leading end surface of the shaft portion of the product. At a time of putting the preliminarily molded product into the full-enclosed forging die so as to mold the product, a relief portion is formed between the leading end surface of the shaft portion to be formed and a cavity of the full-enclosed forging die.

A manufacturing method for a tripod type constant velocity universal joint includes, when forging a raw-shaped material corresponding to each of three journals into a journal shape using a molding surface of a die and in a state where a relief portion is provided on a raw-shaped-material-leading-end-side of the die, molding an outer peripheral surface of the raw-shaped material into a projected round shape. The molding occurring with a tapered surface formed on the molding surface with which the outer peripheral surface of the raw-shaped material is held in contact and a recessed round surface formed between the molding surface and the tapered surface.

Tripod type constant-velocity universal joint and method for producing the same

A forging method and a full-enclosed forging die contribute to the alleviation of an enclosing force applied to dies and in which a relatively small enclosing apparatus can be used even with respect to larger-sized products. A tripod type constant velocity universal joint is formed with a tripod member molded with the full-enclosed forging die. The full-enclosed forging die includes openable/closable dies and punches for pressing a material between the dies. From the forging die, the tripod member including a boss portion and shaft portions protruded radially from the boss portion is molded.

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Iwata, Japan

Shunsuke Makino