TORQUE DETECTING APPARATUS

PURPOSE:To measure the torque with high accuracy and good response by correcting the input/output characteristic of each sensor with an amplifier gain in accordance with the changing amount of a gap from a rotary shaft confronting to a torque sensor and a rotary phase sensor. CONSTITUTION:A cylindrical elastic body 5 provided below a driving shaft 3 of a driller elastically deforms in the radial direction in accordance with the cutting torque of a drill 9. The amount of this deformation is detected by a non-contact sensor 6. Then, the amount is sampled by a rotary phase signal of a non-contact sensor 4 which detects the presence/absence of a marker 2 indicated with a distance of a predetermined angle on the circumference of the driving shaft 3. Accordingly, the change with time of the cutting torque generated in the drill 9 is detected. Each signal amplifier gain of the sensors 6, 4 is increased/decreased so that when a reference gap between the sensor 6 and the elastic body 5 is minutely changed because of the mechanical vibration or change with time, the relation of the reference gap to the sensor output is held. Accordingly, the outputs of the sensors 6, 4 can be kept constant when no load is added. By obtaining a signal proportional to the amount of the gap between the sensors 6, 4, highly accurate measurement of the torque is achieved.