Drive control apparatus for an injection molding machine

Abstract

A drive control apparatus connects a hydraulic source 4 and an oil tank 5 to an injection cylinder 2 through a servo valve 3 and controls the injection cylinder 2 by the servo valve 3. A first change-over valve 6 which is connected between the hydraulic source 4 and the servo valve 3 and has a large capacity. A flow limiting circuit 9 connects a throttle valve 7 to a second change-over valve 8 having a small capacity in series and is connected to the first change-over valve 6 in parallel. A change-over valve control portion 10 opens both the first change-over valve 6 and the second change-over valve 8 when controlling a large rate of flow in an injection process or the like and controls to close the first change-over valve 6 when controlling a small rate of flow in a pressure maintenance process or the like. As a result, the first change-over valve 6 having a large capacity and the second change-over valve 8 (which is connected to the throttle valve 7 in series and has a small capacity) are opened so that the control suitable for the large rate of flow is performed when controlling the large rate of flow. When the first change-over valve 6 having a large capacity is closed, control of a small rate of flow is carried out.

Dependencies are inferred from the claim text.