Injection molding machine for performing foam molding and method for controlling injection molding machine

An injection molding machine comprising:

• a heating cylinder having a gas inlet;
• a screw drivable in the heating cylinder;
• a gas supply device configured to supply a gas to the gas inlet;
• and
• a controller,
• wherein an inside of the heating cylinder is divided into a plurality of sections, and from upstream, the inside of the heating cylinder is divided into a first compression and metering section in which the molten injection material is compressed, a starvation section in which a pressure of the injection material decreases, and a second compression and metering section in which the injection material is compressed again, and wherein the gas inlet is provided in the starvation section,
• wherein the gas supply device comprises:
• a gas supply source configured to supply a gas;
• a pressure adjustment device configured to adjust a primary pressure of a gas from the gas supply source to a secondary pressure;
• a check valve provided downstream of the pressure adjustment device;
• and
• a secondary pressure detection device configured to detect the secondary pressure at a downstream of the check valve,
• wherein the gas inlet is connected to the heating cylinder downstream of the check valve, and the gas supply device is configured to supply the gas at the secondary pressure to the gas inlet,
• wherein the controller is configured to detect an abnormality in a case where the secondary pressure becomes out of a normal pressure range, and
• wherein the normal pressure range, which is a normal pressure range of the secondary pressure, is greater than a value that is obtained by subtracting a second threshold from a set pressure for the gas at the secondary pressure and is less than a value that is obtained by adding a first threshold to the set pressure, the first threshold being a value of 0.1 MPa to 1.5 MPa, and the second threshold being a value of 0.1 MPa to 1.5 MPa.