Shut-off nozzle, injection device, and injection molding machine

An injection device comprising:

• a heating cylinder;
• a screw inserted in the heating cylinder;
• and
• a shut-off nozzle provided in the heating cylinder, the shut-off nozzle comprising:
• a nozzle body portion having a resin flow path formed therein;
• a needle valve insertable in the nozzle body portion coaxially with the nozzle body portion and configured to open and close an outlet of the resin flow path;
• and
• a needle driving mechanism configured to drive the needle valve, the needle driving mechanism comprising:
• a cylinder mechanism provided in the nozzle body portion;
• and
• a spring holder configured to transmit a driving force from the cylinder mechanism to the needle valve,
• wherein the nozzle body portion comprises a valve housing, the valve housing having:
• a needle hole in an axial direction, a rear end portion of the needle valve being insertable into the needle hole;
• and
• a spring holder hole orthogonal to the axial direction,
• wherein the spring holder is inserted in the spring holder hole in a direction orthogonal to the axial direction in a state in which slide in the axial direction is allowed, both ends of the spring holder are fixed to the cylinder mechanism, and a central portion of the spring holder is in contact with or connected with the rear end portion of the needle valve, enabling the needle valve to move forward in the axial direction via the spring holder so as to close the outlet when the cylinder mechanism is driven, and
• wherein enlargement portions are formed in both side surfaces of the valve housing, each of the enlargement portions being continuous with the spring holder hole and having a shape enlarged from the spring holder hole.

An injection molding machine comprising:

• a mold clamping device configured to clamp a mold,
• an injection device configured to inject a resin, the injection device comprising:
• a heating cylinder;
• a screw inserted in the heating cylinder;
• and
• a shut-off nozzle provided in the heating cylinder,
• wherein the shut-off nozzle comprises:
• a nozzle body portion having a resin flow path formed therein;
• a needle valve insertable in the nozzle body portion coaxially with the nozzle body portion and configured to open and close an outlet of the resin flow path;
• and
• a needle driving mechanism configured to drive the needle valve, the needle driving mechanism comprising:
• a cylinder mechanism provided in the nozzle body portion;
• and
• a spring holder configured to transmit a driving force from the cylinder mechanism to the needle valve,
• wherein the nozzle body portion comprises a valve housing, the valve housing having:
• a needle hole in an axial direction, a rear end portion of the needle valve being insertable into the needle hole;
• and
• a spring holder hole orthogonal to the axial direction,
• wherein the spring holder is inserted in the spring holder hole in a direction orthogonal to the axial direction in a state in which slide in the axial direction is allowed, both ends of the spring holder are fixed to the cylinder mechanism, and a central portion of the spring holder is in contact with or connected with the rear end portion of the needle valve, enabling the needle valve to move forward in the axial direction via the spring holder so as to close the outlet when the cylinder mechanism is driven, and
• wherein enlargement portions are formed in both side surfaces of the valve housing, each of the enlargement portions being continuous with the spring holder hole and having a shape enlarged from the spring holder hole.