| 摘要 |
PURPOSE:To prevent occurrence of any defective article for clamping by detecting the shaft torque after lapse of a certain time subsequent to stoppage of a motor and performing screw clamping again in case of a screw clamping machine which detects the shaft torque of a driver bit before cutting off motor driving. CONSTITUTION:A torque sensor 14 which detects the shaft torque is provided on a power transmission shaft 13 of a driver bit 12 driven by means of a pulse motor 11. A value detected by the torque sensor 14 is compared with a predetermined desirable clamping torque value by means of a comparator and, when both values coincide with each other, power supply to the pulse motor 11 is stopped. Comparison between the value detected by the torque sensor 14 and the desirable clamping torque value is made again after lapse of a certain time subsequent to stoppage of the pulse motor 11 and, in case there is any difference between abovementioned two values, the pulse motor is driven again until the value detected by the torque sensor 14 coincides with the desirable clamping torque value. When the value detected by the torque sensor 14 is still lowered even after repetition of said comparison predetermined number of times, the article concerned is regarded as defective one for clamping. |
