An injection unit for an injection molding machine includes a cylindrical body rotatably supported in a housing interior for rotational coupling with a plasticizing screw. The cylindrical body is fixed to rotate with the plasticizing screw about an injection axis. A gear train in the housing includes a central gear mounted about, and fixed to rotate with, the cylindrical body, the central gear having an uppermost extent vertically above the injection axis and opposed first and second lateral extents on horizontally opposed sides of the injection axis. A rotary drive for powering rotation of the plasticizing screw includes a first motor having a first motor shaft rotatable about a first motor axis, the first motor axis parallel to the injection axis, the first motor axis at a first elevation below the uppermost extent of the central gear, and laterally outboard of the first lateral extent of the central gear.

An injection apparatus includes (a) a barrel; (b) a nozzle at a front end of the barrel; (c) a screw in the barrel; and (d) a drive assembly including: (i) a housing having a front end coupled to the barrel; (ii) a spindle in the housing and fixed to the screw; (iii) a first motor in the housing and having a hollow first rotor through which the spindle passes. The first rotor is coupled to the spindle for driving rotation of the screw about the axis. The drive assembly further includes (iv) a second motor in the housing axially rearward of the first motor. The second motor has a hollow second rotor through which the spindle passes. The second rotor is coupled to the spindle for translating the screw along the axis in response to rotation of the second rotor relative to the spindle.

A screw driving device includes: a plasticization motor; a rotation drive shaft provided coaxially with a screw and configured to rotate the screw; and a transmission mechanism configured to decelerate rotation of the plasticization motor and transmit the rotation to the rotation drive shaft. The transmission mechanism includes: a speed reducer whose output shaft is coupled to the rotation drive shaft; a drive rotation member provided in the plasticization motor; a driven rotation member provided on an input shaft of the speed reducer; and one endless string-shaped force transmission member wound around the drive rotation member and the driven rotation member.

An injection molding apparatus and method of fabricating a molded part are provided. The apparatus may include a barrel, a nozzle enclosing an end of the barrel and defining an opening in fluid communication with an inside of the barrel, and an extrusion screw positioned at least partially inside the barrel and rotatable relative to the barrel. The extrusion screw may include a screw tip. Relative axial movement between the barrel and the extrusion screw may open or close the opening of the nozzle to permit or prevent, respectively, material flow through the opening of the nozzle. The method may include clamping a mold, opening a nozzle, rotating the extrusion screw to pump a molten material into the mold until the mold is filled, closing the nozzle, and unclamping the mold to release a molded part.

In a configuration in which a guide member that guides an intermediate member to be slidably movable is provided on an upper surface of side support plates, a bending buffer portion is provided in a first region of the side support plates which is located more outward than a part of the side support plates on which the guide member is provided. The bending buffer portion is configured to be bent and deformed easier than a second region of the side support plates in which the guide member is provided.

In a configuration in which a guide member that guides an intermediate member to be slidably movable is provided on an upper surface of side support plates, a bending buffer portion is provided in a first region of the side support plates which is located more outward than a part of the side support plates on which the guide member is provided. The bending buffer portion is configured to be bent and deformed easier than a second region of the side support plates in which the guide member is provided.

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.

A stepped flight is formed on a screw of an injection molding machine. The stepped flight is a flight in which a step-shaped step portion is formed on a top portion thereof. The top portion of the flight includes a large diameter portion on an upstream side and a land portion on a downstream side. When a gap ratio m of a gap H.sub.1 between the land portion and a bore of the heating cylinder to a gap H.sub.2 between the large diameter portion and the bore is defined as H.sub.1/H.sub.2, the gap ratio m is selected to be 2.3≤m≤6.4.

A flange is formed on a heating cylinder in a vicinity of a center in a longitudinal direction and a predetermined joining plate adheres to the flange. A flange plate is provided on a support frame. The joining plate is fixed to the flange plate to attach and detach freely, and the heating cylinder is caused to be supported by the support frame. Accordingly, movement in an axial direction and rotation of the heating cylinder are restricted. A guide portion for positioning during attachment and detachment is provided on one or both of the joining plate and the flange plate.

A plasticizing device includes a plasticizing section that includes a feeding port for receiving a material and plasticizes the material to generate a melted material, a material feeding section that includes a depositing port communicating with the feeding port and feeds the material from the depositing port to the plasticizing section, and a blowing section that blows gas into a feeding path connecting the depositing port and the feeding port.