MANUFACTURE OF YOKE UNIVERSAL JOINT HAVING SHANK

摘要

PURPOSE:To obtain a yoke provided with a shank, which generates no burr and has a high strength, by constituting it so that a coarse arm part can be elongated and formed by crushing and pressing a coarse yoke part of a coarse forming member by a punch having an upper slanting forming surface, in an arm elongating process. CONSTITUTION:In a preforming process, a coarse forming member 15 consisting of a coarse shank 16 and a coarse yoke part 17 is brought to a cold extrusion forming. In an arm elongating process, the coarse yoke part 17 is crushed and pressed by a punch P having a wedge-shaped forming part A of a radius R, a receiving hole 26 for inserting through the coarse shank 16, a recessed part 27 for forming a coarse base part 20, and a die having a forming surface 28 of an angle alpha in the X direction of the right and left. A preforming member 19 by which a coarse arm part 21 has been elongated and formed in the X direction is subjected to crush-forming of the coarse base part 20, and bending and iron-forming of the coarse arm part 21, and becomes a yoke member 30 having an arm 7. In this way, a yoke provided with a shank, which generates no burr and has a high strength can be formed.