Ball-lead screw unit and injection moulding machine with the unit

The present invention provides a device for a ball screw linear motion of the device by using a plurality of ball screw shaft and ball screw nut single mobile body. In the ball screw unit, the ball screw nut and a plurality of identical threaded engagement of the ball screw shaft, and in each one of the respective screw nut of the ball screw shaft is fixed by a flange secured to the body work , a single fixed flange or flanges each provided with one fixed load cell, while the other as the ball screw nut hydraulic cylinder and a hydraulic piston support mechanism. Hydraulic fluid pressure is controlled to be equal to the force support mechanism supporting the thrust load detected by the sensor. With this structure, the larger the load evenly distributed on the ball screw nut.