Central Motor Wheel Co., Ltd.

Kazuya Mori

Yukitaka Murakami

Shinji Hashimura

Method of fixedly connecting together externally and internally threaded tubes by tight engagement of externally and internally threaded portions of the tubes, wherein a wrenching operation is performed to rotate the externally and internally threaded tubes relative to each other with the externally and internally threaded portions engaging each other while an axial force is applied 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.

Apparatus for fixedly connecting threaded tubes, and recording medium storing control program

Method and apparatus for fixedly connecting threaded tubes, and recording medium storing control program for practicing or controlling those method and apparatus

An elevator carrying a motor for rotating a socket wrench is lowered by a hydraulic cylinder while being guided by a linear guide, such that the socket wrench is rotated by the motor while the socket wrench is in engagement with the head of a bolt, with a compressive force being applied to the bolt based on a hydraulic pressure of the cylinder, and such that a wrenching torque and the compressive force acting on the bolt is detected by a detector. A coefficient of friction between thread surfaces of the bolt and an internal thread is evaluated based on the wrenching torque in an initial stage of wrenching operation in which the bolt head is spaced apart from a workpiece, while a coefficient of friction between the bolt head and the workpiece is evaluated based on the wrenching torque in an intermediate stage in which the thread surfaces of the bolt and the internal thread are spaced apart from each other immediately after contacting of the bolt head and the workpiece. The wrenching operation is terminated when actual wrenching torque reaches a target wrenching torque determined from the friction coefficients.

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Kurume, Japan

Kazuya Mori