Patent ID: 7677875

Claim:
An in-line screw injection molding machine using servo-motors as a measurement driving source and an injection driving source, comprising: means for controlling driving of said measurement servo-motor by open control with a constant set rotational velocity of a screw and controlling driving of said injection servo-motor by back pressure feedback control in which an astern speed of said screw is controlled to follow a set value of back pressure set in advance, in a period between a measurement start position and a measurement control changeover position on a measuring stroke; means for controlling driving of said injection servo-motor by open control following an astern speed setting pattern and controlling driving of said measurement servo-motor by back pressure feedback control in which said rotational velocity of said screw is controlled, in a period between said measurement control changeover position and a measurement completion position; wherein control is made so that all of a measured value of said back pressure controlled by said measurement servo-motor, a measured value of said astern speed of said screw controlled by said injection servo-motor, and a measured rotational speed of said screw turn zero concurrently at timing when said screw reaches said measurement completion position.