Mitsubishi Denki Kabushiki Kaisha

Kabushiki Kaisha Terauchi Seisakusho

Toshio Akiyoshi

Tsutomu Onishi

Shozo Haikawa

Hakushi Shibuya

A power wrench, or clamping tool, for tightening a bolt, nut and the like comprising a power shaft engaging the bolt, nut and the like, a driving power source of electromotive, pneumatic or hydraulic type, an anti-reaction force member for the prevention of rotation of the tool case due to the reaction force, a harmonic drive mechanism as the speed reduction mechanism between the power shaft and the driving power source, planetary gear device provided between the harmonic drive mechanism and the power shaft, a first mechanism engaged with a nut screwed to a torque set bolt and rotating the nut with the rotation of the power shaft thereby tightening the nut, a second mechanism engaged to the torque set bolt in such a way as to break the torque set bolt at a predetermined position when the tightening torque arrives at a predetermined value in the course of the clamping and a knock out mechanism which discharges the broken piece of the torque set bolt out of the case by means of a spring force. The tool case rotates with respect to a handle under relatively high frictional restraint to prevent the handle from rotation during the breakage or failure of the anti-reaction force member, and the anti-reaction force member is rotatable freely to a limited degree with respect to the tool case for locating the anti-reaction force member in contact with an adjacent nut and bolt to the nut being torqued down by the power wrench.

Power wrench

A clamping or power wrench tool for tightening a bolt, nut and the like comprising a power shaft engaging the bolt, nut and the like, a driving power source of electromotive, pneumatic or hydraulic type, an anti-reaction force member for the prevention of rotation of the tool case due to the reaction force, a harmonic drive mechanism as the speed reduction mechanism between the power shaft and the driving power source, planetary gear device provided between the harmonic drive mechanism and the power shaft, a first mechanism engaged with a nut screwed to a torque set bolt and rotating the nut with the rotation of the power shaft thereby tightening the nut, a second mechanism engaged to the torque set bolt in such a way as to break the torque set bolt at a predetermined position when the tightening torque arrives at a predetermined value in the course of the clamping and a knock out mechanism which discharges the broken piece of the torque set bolt out of the case by means of a spring force.

Clamping tool

A clamping tool is provided with an electric motor as a driving source of the tool. The condition of the axial force of the clamping means, such as a bolt and nut, on the clamped elements, such as metal sheets is detected by monitoring one of the following quantities of the motor or motor circuit: current, voltage, numbers of rotation, and electric power of said electric motor. When the differential coefficient of the measured quantity reaches approximately zero, after the transient starting conditions have subsided, the motor is stopped. This occurs substantially at the yielding point of the clamping means.

Growing community of inventors

Fukuoka, Japan

Toshio Akiyoshi