Patent ID: 7915850

Claim:
An apparatus comprising: a motion controlling unit comprising: a position order generator capable of outputting a first position command; a first servomotor position controller and a second servomotor position controller, both servomotor position controllers are connected to the position order generator for receiving the first position command; a first driving amplifying unit connected to the first servomotor position controller, wherein the first driving amplifying unit is configured to receive a second position command from the first servomotor position controller, and the first driving amplifying unit comprises a first position controller connected to the first servomotor position controller; a second driving amplifying unit connected to the second servomotor position controller, wherein the second driving amplifying unit is configured to receive a third position command from the second servomotor position controller, and the second driving amplifying unit comprises a second position controller connected to the second servomotor position controller; and a first servomotor and a second servomotor connected to the first and second driving amplifying units respectively, wherein the first servomotor is connected to the first position controller to form a first servomotor position feedback circuit, and the second servomotor is connected to the second position controller to form a second servomotor position feedback circuit; a first screw cap and a second screw cap respectively mounted to ball screws of the first and second servomotors; a mounting element for mounting an injection screw connected to the screw caps; first and second position detectors are associated with the screw caps capable of detecting absolute positions of the corresponding screw caps, the first and second screw caps connected to the first and second servomotor position controllers respectively to form a first and a second screw cap position feedback circuits.