| 摘要 |
A pair of rolls each having a peripheral groove in which there is an embossed half-thread. The rolls are on parallel shafts which are driven by a pinion stand. The pinion stand is provided with a device for making a vernier adjustment of the top roll's circumferential or rotational angle position with respect to the bottom roll so that the half-threads thereon will impress a smooth, continuous full thread on a rod passing between the rolls. One shaft is driven through the vernier device which comprises a coupling element in which there are two sets of internal gear teeth one of which is straight and the other of which is helical. The coupling element is rotated with a hollow gear which meshes with the straight internal teeth. A driven shaft extends out of the coupling element through the hollow gear and has a gear which engages with the internal helical teeth. Shifting the coupling element axially causes it to slide on the straight teeth and effect a torque on the helical teeth which changes the phase angle of the shaft of the top roll with respect to the shaft of the bottom roll and effects the desired rotational angle correction between the rolls.
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