An injection molding apparatus includes an electric motor, a torque variable mechanism that changes an output torque of the electric motor, and a screw driving unit that transmits the output torque of the torque variable mechanism to a feed screw, whereby the feed screw is turned by the electric motor, the torque variable mechanism and the screw driving unit. The torque variable mechanism applies, to the feed screw, a torque equivalent to a hydraulic drive. The electric motor is interchangeable with a hydraulic motor to enable the injection molding apparatus to change between electric and hydraulic drive of the feed screw.

An injection molding machine is equipped with a screw having a spline shaft formed with a spline on an outer circumferential surface, a bush having a spline hole formed with a spline on an inner circumferential surface, a linear motion motor for moving the bush in an axial direction of the screw, a rotational motion motor for rotating the bush about an axis of the screw, and a motor control unit which, in the case of fitting the spline shaft in the spline hole, controls the linear motion motor to advance the bush in a direction approaching the screw in a state that the bush and the screw are separated, and which controls the rotational motion motor to rotate the bush when the acquired output torque becomes equal to or larger than a first predetermined torque.

An injection molding apparatus is on the basis of a hydraulic injection molding device, and the apparatus includes an electric motor, a torque variable mechanism that changes output torque by the electric motor, and a screw driving unit that transmits the output torque by the torque variable mechanism to a screw. The screw is turned by the electric motor, the torque variable mechanism, and the screw driving unit. The torque variable mechanism applies, to the screw, torque equivalent to a hydraulic drive.

An embodiment of the present invention provides an injection device including a screw that includes a plurality of outer circumferential protrusions, each of the plurality of outer circumferential protrusions being provided with an outer circumferential protrusion slope and a second outer circumferential protrusion slope. A bush of the injection device includes a plurality of inner circumferential protrusions, each of the plurality of inner circumferential protrusions being provided with an inner circumferential protrusion slope and a second inner circumferential protrusion slope. A rear end of each of the plurality of outer circumferential protrusions and a front end of each of the plurality of inner circumferential protrusions include no flat surface.

An injection device includes a spline supporting member rotatably supporting a spline shaft and attached to a pressure plate, and a nut supporting member rotatably supporting a spline nut and attached to a rear plate. The spline supporting member is provided with a spline positioning mechanism for adjusting the mounting position of the spline supporting member. The nut supporting member is provided with a nut positioning mechanism for adjusting the mounting position of the nut supporting member. The spline supporting member and the nut supporting member are formed with holes for axial-center checking, rods being inserted through the holes.

An injection molding machine is equipped with a screw having a spline shaft formed with a spline on an outer circumferential surface, a bush having a spline hole formed with a spline on an inner circumferential surface, a linear motion motor for moving the bush in an axial direction of the screw, a rotational motion motor for rotating the bush about an axis of the screw, and a motor control unit which, in the case of fitting the spline shaft in the spline hole, controls the linear motion motor to advance the bush in a direction approaching the screw in a state that the bush and the screw are separated, and which controls the rotational motion motor to rotate the bush when the acquired output torque becomes equal to or larger than a first predetermined torque.

An injection device includes a spline supporting member rotatably supporting a spline shaft and attached to a pressure plate, and a nut supporting member rotatably supporting a spline nut and attached to a rear plate. The spline supporting member is provided with a spline positioning mechanism for adjusting the mounting position of the spline supporting member. The nut supporting member is provided with a nut positioning mechanism for adjusting the mounting position of the nut supporting member. The spline supporting member and the nut supporting member are formed with holes for axial-center checking, rods being inserted through the holes.