Metering system of injection molding machine

Claim 1

A metering system of an injection molding machine, including a numerical control unit comprising: a first servo motor for diving a screw of the injection molding machine in an axial direction a second servo motor for rotating said screw; position detecting means for detecting a position of said screw; and memory means for storing a screw rotating speed command value and a torgure limit value in correspondence with a screw position, said numerical control unit having a torque limit function, said numercal control unit, during a metering process, reading out the screw rotating speed command value and the torque limit value from said memory means in accordance with the screw position detected by said position detecting means, and outputing the the readout screw rotating speed command value to said second servo motor and the readout torque limit command value to said first servo motor, thereby controlling a rotating speed of said screw in accordance with the screw position, and controlling an output torque of said first servo motor to a value below the readout torque limit command value for controlling a back pressure of said screw in accordance with said screw position.