Abstract: A mold clamping unit comprises guide rollers for guiding fitting and releasing of a mold, a hydraulic clamp for holding the mold at a molding position, a guiding portion formed to project in a direction perpendicular to a mold open-close direction from a lower portion of platen and a locking mechanism provided to an upper portion opposing to the guiding portion for the platen, for locking the mold at a releasing position. Since exchange and maintenance operations of a stamper can be carried out under a condition where the mold is released to the releasing position over the guiding portion and locked by the locking mechanism, fitting/releasing of the mold to/from the platen can be facilitated and exchange and maintenance operations of the stamper can be made easy.

Abstract: A combination of displacement mechanisms adaptive for positioning a stationary platen to a frame, permitting the stationary platen to be displaced toward an injection unit to allow an escaping extension of tie-rods in a mold clamp action, is operative to displace the same toward the injection unit for a maintenance service, so that it can be displaced toward the injection unit further from a molding position in a molding operation.

Abstract: A stationary platen for holding a stationary part of a mold centered to an injection axis is securely connected by tie-rods to a cylinder body integral with a cylinder part of a clamp cylinder which moves a movable part of the mold in a clamp direction, and subjected to a deformation when the mold is clamped, which deformation is made symmetrical with respect to a reference plane including the injection axis by a combination of mechanisms therefor.