The invention relates to screw thread screw-up machine based on servo system. Its features are that the servo motor is used as the driving mechanism. Reducing mechanism and toque sensor are set between the driving and output mechanism. The reducing mechanism is adopted two grade reducing; the first grade is planet gear train; the second grade is low tooth difference driving. It is adopted dynamic toque sensor; one end of the strain axis of the sensor is directly connected to the output end of the reducing mechanism; the other end is directly connected to the spline housing used as the driving input in the output mechanism. The invention possesses high assembling efficiency and high assembling precision, especially suits to motor dom, can realize relatively precise control to the screwing up of the bolt. |