Method and apparatus for fast threading pullout in a numerically controlled threading application

A method for use with a numerically controlled threading machine for accelerating a pullout of a machine member from a thread on a workpiece, the method comprising the steps of:

• receiving position command signals from a numerical control for determining commanded movement of the machine member;
• generating a first velocity signal based on the commanded movement for driving the machine member along a pullout axis;
• generating a supplemental velocity signal for movement of the machine member along the pullout axis;
• adding the supplemental velocity signal to the first velocity signal when the commanded movement of the machine member reaches a selected position on the thread, to produce an accelerated pullout movement of the machine member along the pullout axis;
• monitoring the accelerated pullout movement of the machine member;
• and
• discontinuing the supplemental velocity signal after a portion of the pullout movement.

An apparatus for use with a numerically controlled threading machine for decreasing the time for pullout of a machine member from a thread on a workpiece along a pullout axis, the apparatus comprising:

• position determining logic structure in communication with the numerical control to receive position command signals from the numerical control and determine commanded movement of the machine member;
• at least one machine member position sensor;
• velocity calculation structure in communication with the position determining logic structure and the sensor to determine a commanded velocity for the machine member from the commanded movement and the sensed position of the machine member;
• and
• supplemental velocity structure adapted to apply a supplemental pullout velocity to the machine member along a pullout axis when the commanded movement reaches a preselected position the supplemental pullout velocity being applied to the machine member in addition to the commanded velocity.