| 摘要 |
PURPOSE:To improve the work efficiency of an equal speed universal joint tire provided with a spherical internal circumference surface and a ball groove having a curved-line ball rolling track, by reducing the area of a tire raw material having an elliptic internal circumference surface from its external circumference with a conically drawn die while restraining the internal circumference with a split die punch. CONSTITUTION:The internal circumference surface Wa of a raw material W for a tire is made into a nearly conic surface which spreads from a maximum diameter part to an opening end Wc, a ball groove Wb is formed nearly linearly from its maximum diameter part to the opening end Wc, and an escape groove Wf having prescribed width and depth is formed at a spherical internal circumference surface part between the ball grooves Wb. Then, the raw material W is fitted by restraining a split die punch 17 as the curved-surface forming member of the internal surface of the contractible raw material, and this is reduced in area from its external circumference in the radius direction with drawing dices 11 and 12 which have nearly conic internal circumference surfaces, thus obtaining the tire 2 of an equal speed universal joint. |
