CLOSING DEVICE FOR INJECTION MOLDING MACHINE

PROBLEM TO BE SOLVED: To perform an accurate injection compression molding. SOLUTION: In a closing state in which almost no closing force is applied, a solenoid (a) of a solenoid operable switch-over valve 8 is deenergized, and fused resin is injected from an injection device 14 into a cavity by virtue of the forward movement of an injection screw. This resin pressure opens up the parting surfaces of molds to produce a compression margin. When an injection screw moves to a preset position, a piston rod 20r of an auxiliary cylinder 20 is moved rightward by virtue of the operation of an electric motor 25. This press sends a working fluid in an auxiliary fluid chamber 20a of the auxiliary cylinder 20 into a closing side fluid chamber 1a of a closing cylinder 1, and the working fluid so sent moves a piston rod 1r rightward, and therefore the molds are closed by a predetermined pressure over the compression margin. Since the auxiliary cylinder 20 is constructed to be operated by the electric motor 25, the position and moving speed of a cross head 2a can be controlled in many steps with accuracy.