| 摘要 |
PROBLEM TO BE SOLVED: To provide a screw treated producing method and apparatus which enable one to reduce a production cost by shortening processing hours and to select at random an opening position of the threading on the peripheral surface of a workpiece. SOLUTION: Relatively rotating a hardware for threading (a round die for thread rolling) 27 and a workpiece (a shaft like workpiece constituting a main hardware for a spark plug), the rotational angle position of the tool 27 is detected, an opening commencement signal is announced under a predetermined condition, and the tool 27 begins to threading (thread rolling) sticking fast to the workpiece W. The angle position signal which triggers to transmit the opening commencement signal can use the output signal for an encoder 28 which detects the rotational angle position of the tool 27 and the encoder 28 is provided on the motor spindle 21a which rotates synchronously to the rotation shaft 26 of the tool 27.
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