| 摘要 |
A tool couple which is used with a manually-operated threading die to aid in cutting the initial threads on a pipe or bolt. The device is used to force the anterior cutting edge of the die firmly against the outer, unthreaded surface of the workpiece at the outset of a threading operation. The die is kept wedged, as the initial threads are being cut, between the workpiece and a rotatable member of the tool couple so that the die cannot slip backward toward and merely chamfer the leading edge of the workpiece. To keep the die so wedged, the rotatable member is advanced by means of a shaft in the direction of the end of the workpiece at approximately the same rate as the die is moved along the longitudinal axis of the workpiece. Usually only one revolution of the threading die, assisted by the tool couple, is required to establish the starting thread. The rotatable member, which dissipates torque developed during the threading operation, is retained in general alignment with the die by a protrusion in the shape of a shallow truncated cone on the face of the member which is adapted to extend a short distance into the central passageway of the die. A frame supporting the shaft can be swung out of the way once sufficient threads have been cut on the workpiece to hold the threading die in place.
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