| 摘要 |
The ball screw comprises a shaft (1) including a spiral-shaped shaft groove (1a) having a semicircular-shaped (Gothic-arch-shaped) section, a nut including a spiral-shaped nut ball groove (3a) which corresponds to the shaft groove and has a semicircular-shaped (Gothic-arch-shaped) section, a large number of balls rotatably fitted into between the nut ball groove and shaft groove in such a manner that they are held by and between these two grooves, and a circulation member capable of defining a ball circulation passage for allowing the balls to circulate endlessly therethrough, wherein a portion of the nut ball groove (R2) is formed larger in the effective diameter than the remaining portions of the nut. <IMAGE> <IMAGE> |
