| 摘要 |
PURPOSE:To enable a thread in a predetermined length to be correctly and smoothly cut, by engaging a ball with and disengaging it from an engagement hole in a longitudinal moving member and lifting a guide ring by the ball. CONSTITUTION:A ball 27 is engaged with a ball press moving hole 25 and an engagement hole 26, and a ball holding ring 28, having a fitting groove 29 fitting a part of the ball 27 is movable in the direction of an axial line but unable to rotate relatively with respect to a holder 3 by a ball 30 and a key groove 31. A main until 1, if it is rotated in a tapping direction, integrally rotates by forward rotation of a spindle, rotating also a longitudinal moving member 7 and a tap 9 in the same direction, and the tap 9, being fitted to a hole of a work piece ad cutting a thread by rotating and advancing movement in the axial line direction, is stopped after advancing by the length that an engaging length l of the ball 27 with the engagement hole 26 is subtracted from a length of the thread. If the spindle is reversed, the main unit, fitting the ball 27 to a recessed part 52, reverse a ring 47, member 7 and the tap 9. |
