INJECTION MOLDING MACHINE AND CONTROL METHOD THEREOF

To provide a simple-structured injection molding machine capable of effectively suppressing deterioration of molding qualities and a control method of this injection molding machine.SOLUTION: The injection molding machine 1 controls in a manner that in a pressure holding operation (pressure holding process), an in-mold resin pressure Pc which is a pressure of a resin material in a mold cavity 4 becomes a pressure holding objective pressure value Ps. Then, during the pressure holding operation, when an in-injection cylinder resin pressure Pi which is a pressure of the resin material in an injection cylinder 11 reaches a pressure holding upper limit pressure value Pu, forward/backward motion of a screw 12 is regulated until a pressure holding period Th has passed.SELECTED DRAWING: Figure 4 【課題】成形品の品質の低下を効果的に抑制できる簡易な構成の射出成形機およびこの射出成形機の制御方法を提供する。【解決手段】射出成形機１は、保圧動作（保圧工程）においてキャビティ４内の樹脂材料の圧力である金型内樹脂圧Ｐｃが保圧目標圧力値Ｐｓとなるように制御する。そして、保圧動作中に、射出シリンダ１１内の樹脂材料の圧力である射出シリンダ内樹脂圧Ｐｉが保圧上限圧力値Ｐｕに到達したとき、保圧期間Ｔｈが経過するまでスクリュー１２の前後進を規制する。【選択図】図４