PURPOSE: To increase the accuracy of detection and the life, by specifying the installed location of strain gauge.
CONSTITUTION: The strain gauge 14 is fitted to the flange tube 13 which is externally inserted to the main shaft 12 coupled with the output shaft 11a of the rotary drive source 11, in which the upper end is fixed to the driver case 10 and the lower end is fixed to the external cylinder 15 of the planet gear set having the inner tooth 15a. Thus, the driver A is lifted down with the operation of the lifting up and down air cylinder 4, and the bit 20 is turned through the main shaft 12, planet gear, gear support 17, follower shaft 18, and torque adjusting spring 27 with the rotation drive source 11, and when the screw is tightened, the reaction due to the progress of tightening is detected with the strain gauge 14, and the number of revolution of the rotary drive source 11 is controlled. Further, since the strain detection section has no contact and rolling part and the signal is directly obtained from the strain gauge 14, the specified purpose can be achieved.
YOMO OSAMU
SUGIURA HIROTADA
