| 摘要 |
Means for controlling the advance of a thread forming member include a unidirectionally driven constant speed spindle, with the spindle mounting a thread forming member. A lead screw and a nut threadedly mounted thereon have a thread in which the helix angle is sufficiently high that the nut is freely rotatable relative to the lead screw in response to axial movement of the lead screw. The lead screw or the nut is attached to the spindle. There are means for controlling rotation of the other of these two members independently of the member attached to the spindle and during unidirectional constant speed rotation of the spindle to thereby control axial movement of the spindle.
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