Patent ID: 6144891
Filing Date: 2000-11-07
Classification: B23P,B25B

Abstract:
A method of tightening a workpiece between an externally threaded member and an internally threaded member, by rotating a rotary threaded member which is one of said externally and internally threaded members, while said externally and internally threaded members are held in engagement with each other and while a stationary threaded member which is the other of said externally and internally threaded members is prevented from being rotated, said method comprising:detecting an actual initial value of a wrenching torque acting on said rotary threaded member while said rotary threaded member is rotated with an axial force acting thereon, in an initial stage of a wrenching operation in which a seat surface of said rotary threaded member is spaced apart from a seat surface of said workpiece;determining a terminating condition for terminating said wrenching operation, on the basis of the detected actual initial value of the wrenching torque; andterminating said wrenching operation when said terminating condition is satisfied.