Patent ID: 8641400

Claim:
A mold clamping apparatus comprising: a mold block comprising a stationary die plate that holds a stationary mold and a movable die plate that holds a movable mold; a die plate moving means that moves the movable die plate toward and away from the stationary die plate; and a mold clamping means that connects and pressurizes the stationary die plate and the movable die plate, wherein the mold clamping means includes a plurality of mold clamping cylinders provided on one of the stationary die plate and the movable die plate, a plurality of tie bars each having one end connected to a ram of the mold clamping cylinder, and the other end having a plurality of ring grooves or screw grooves at regular pitches, a half nut provided on the other of the stationary die plate and the movable die plate and engageable with the plurality of ring grooves or screw grooves, a hydraulic pipe communicating with each of the plurality of mold clamping cylinders, a hydraulic source including a hydraulic pump that supplies oil to the hydraulic pipe, and a control device that controls the supply of the oil from the hydraulic source to the hydraulic pipe, the control device controls the supply of the oil based on a mold clamping force by each of the plurality of tie bars determined correspondingly to an estimated mold opening force by mold internal pressure for molding with the mold internal pressure being asymmetrical with respect to a center of the mold block, the hydraulic pipe comprising a common pipe, an auxiliary pipe, and a changeover valve connected to the common pipe and the auxiliary pipe, said changeover valve provided correspondingly to the hydraulic source, and the control device is configured to control the changeover valve depending on a flow amount of the oil required by the mold clamping cylinder.