Method and apparatus for fixedly connecting threaded tubes, and control program for their use

摘要

Method of fixedly connecting together externally and internally threaded tubes (18, 14) by tight engagement of externally and internally threaded portions (122, 124) of the tubes, wherein a wrenching operation is performed to rotate the externally and internally threaded tubes (18, 14) relative to each other with the externally and internally threaded portions (124, 122) engaging each other while an axial force is applied so as to act between the tubes. A physical quantity relating to a coefficient of friction between said tubes is obtained on the basis of a detected wrenching torque applied to rotate the tubes relative to each other and the axial force, and a terminating condition for terminating the wrenching operation is determined on the basis of the obtained physical quantity. The wrenching operation is terminated when the terminating condition has been satisfied. Apparatus for practicing the method and recording medium storing a control program for the method are also disclosed.