An injection molding machine including a mold clamping device for clamping a mold comprising a fixed mold and a movable mold by a predetermined mold clamping force; an injection device for injecting and filling a resin into the mold by a predetermined injection pressure, wherein the mold clamping device enables natural compression of the resin at least as the resin inside the mold solidifies; and a molding machine controller at least including a specific molding condition setting function for setting a specific molding condition by obtaining a parting opening amount which becomes a predetermined gap between the movable mold and the fixed mold during injection filling, a molding injection pressure which becomes an injection pressure capable of molding a good product and a molding clamping force which becomes a mold clamping force capable of molding a good product; a fast injection condition setting function for setting, as a fast injection condition, a fast injection speed from the start of injection, the fast injection speed being higher than the injection speed set by the specific molding condition, and a fast injection section for continuing the fast injection speed; and a molding control function for mold-clamping the mold clamping device by the molding clamping force, setting the molding injection pressure to a limit pressure, injecting and filling the mold by the fast injection condition from the start of injection, and filling the mold by the specific molding condition by the end of the fast injection section.

A run-around circuit makes a hydraulic fluid discharged from a rod-side chamber along with a forward movement of a piston in an injection cylinder flow into a head-side chamber. A servo valve is provided in the run-around circuit and is connected to a tank. In a first state, the servo valve permits flow from the rod-side chamber to the head-side chamber, while prohibits flow from the rod-side chamber to the tank. In a second state, the servo valve prohibits flow from the rod-side chamber to the head-side chamber, while permits flow from the rod-side chamber to the tank. The servo valve can control the flow rate of the hydraulic fluid discharged from the rod-side chamber in each of the first state and second state.

A run-around circuit makes a hydraulic fluid discharged from a rod-side chamber along with a forward movement of a piston in an injection cylinder flow into a head-side chamber. A servo valve is provided in the run-around circuit and is connected to a tank. In a first state, the servo valve permits flow from the rod-side chamber to the head-side chamber, while prohibits flow from the rod-side chamber to the tank. In a second state, the servo valve prohibits flow from the rod-side chamber to the head-side chamber, while permits flow from the rod-side chamber to the tank. The servo valve can control the flow rate of the hydraulic fluid discharged from the rod-side chamber in each of the first state and second state.

Injection unit (3) comprises: cylinder (32); screw (33) at least a part of which is housed in cylinder (32) and that is rotatable and movable in an axial direction of cylinder (32); drive shaft (42) that drives screw (33); connecting shaft (41) that connects screw (33) and drive shaft (42); and support member (52) that is located between screw (33) and drive shaft (42), that allows connecting shaft (41) to rotate and move axially, and that supports connecting shaft (41) at least in the vertical direction.

A hydraulic circuit for opening and closing a mould of an injection moulding machine, and an injection moulding machine system includes an operating oil cylinder and a proportional valve; by means of adjusting the proportional valve to different operating states, the operating oil cylinder can be controlled to execute different actions, so as to control mould opening, mould closing and mould differential closing of the injection moulding machine. By means of a differential proportional valve with a flow regeneration function, the present invention can effectively increase control precision in a mould opening and closing process, reduce energy consumption and the number of parts of a system, and save on space taken up by the system, with complete functions of mould opening and closing also being realizable.

A hydraulic circuit for opening and closing a mould of an injection moulding machine, and an injection moulding machine system includes an operating oil cylinder and a proportional valve; by means of adjusting the proportional valve to different operating states, the operating oil cylinder can be controlled to execute different actions, so as to control mould opening, mould closing and mould differential closing of the injection moulding machine. By means of a differential proportional valve with a flow regeneration function, the present invention can effectively increase control precision in a mould opening and closing process, reduce energy consumption and the number of parts of a system, and save on space taken up by the system, with complete functions of mould opening and closing also being realizable.

A mold clamping apparatus includes a mold clamping cylinder. The mold clamping cylinder has, in a region thereof located below left and right lower tie bars and above left and right sliders, a left grooved portion opened leftward and elongated horizontally, a right grooved portion opened rightward and elongated horizontally, and a leg portion formed between the left and right grooved portions. The leg portion and the left and right grooved portions together form a constricted part.

A mold clamping apparatus includes a mold clamping cylinder. The mold clamping cylinder has, in a region thereof located below left and right lower tie bars and above left and right sliders, a left grooved portion opened leftward and elongated horizontally, a right grooved portion opened rightward and elongated horizontally, and a leg portion formed between the left and right grooved portions. The leg portion and the left and right grooved portions together form a constricted part.

A mold clamping apparatus includes a fixed platen, a mold clamping cylinder, a movable platen moved by the mold clamping cylinder toward the fixed platen, and a mold opening/closing actuator for moving the movable platen or the mold clamping cylinder. The mold clamping apparatus further includes a mold thickness adjustment cylinder provided between the mold clamping cylinder and the movable platen, the mold thickness adjustment cylinder being configured to generate an axial force larger than an axial force in an expanding direction of the mold opening/closing actuator and smaller than an axial force in a contracting direction of the mold clamping cylinder.

A mold clamping apparatus includes a fixed platen, a mold clamping cylinder, a movable platen moved by the mold clamping cylinder toward the fixed platen, and a mold opening/closing actuator for moving the movable platen or the mold clamping cylinder. The mold clamping apparatus further includes a mold thickness adjustment cylinder provided between the mold clamping cylinder and the movable platen, the mold thickness adjustment cylinder being configured to generate an axial force larger than an axial force in an expanding direction of the mold opening/closing actuator and smaller than an axial force in a contracting direction of the mold clamping cylinder.