An injection molding machine includes a cylinder that accommodates a molten resin, a discharging nozzle, a piston that discharges the molten resin from the discharging nozzle, and one or more processors configured to execute the following functions. The functions include calculating a target pressure at which a flow rate of the molten resin discharged from the discharging nozzle becomes an indicated flow rate, controlling a pressure of the molten resin in the cylinder such that the pressure becomes the target pressure, acquiring a temperature of the molten resin in the cylinder, and acquiring a pseudo-plastic viscosity corresponding to the temperature of the molten resin. The target pressure is calculated based on the indicated flow rate, the temperature of the molten resin, the pseudo-plastic viscosity, and the size of the discharging nozzle.

An injection molding machine includes a cylinder that accommodates a molten resin, a discharging nozzle, a piston that discharges the molten resin from the discharging nozzle, and one or more processors configured to execute the following functions. The functions include calculating a target pressure at which a flow rate of the molten resin discharged from the discharging nozzle becomes an indicated flow rate, controlling a pressure of the molten resin in the cylinder such that the pressure becomes the target pressure, acquiring a temperature of the molten resin in the cylinder, and acquiring a pseudo-plastic viscosity corresponding to the temperature of the molten resin. The target pressure is calculated based on the indicated flow rate, the temperature of the molten resin, the pseudo-plastic viscosity, and the size of the discharging nozzle.

An injection molding machine capable of changing the position of the supply hole of the resin material in a cylinder as appropriate is provided. An injection molding machine according to one aspect of the present disclosure includes: a supply hole through which a resin material is supplied to an inside of a cylinder, the supply hole being formed in a side wall part of the cylinder; and a closing part that, when a torpedo piston moves to a side of an other end part of the cylinder in order to plasticize the resin material, moves together with the torpedo piston and closes the supply hole.

An injection molding machine capable of changing the position of the supply hole of the resin material in a cylinder as appropriate is provided. An injection molding machine according to one aspect of the present disclosure includes: a supply hole through which a resin material is supplied to an inside of a cylinder, the supply hole being formed in a side wall part of the cylinder; and a closing part that, when a torpedo piston moves to a side of an other end part of the cylinder in order to plasticize the resin material, moves together with the torpedo piston and closes the supply hole.

An injection molding apparatus has a mold tool that is positioned around a field joint of a pipeline to define a mold cavity. Two or more pumping chambers communicate with the mold tool. Each chamber is expansible to draw in molten polymer and contractible to drive the polymer into the mold cavity. Expansion of one chamber is synchronized with contraction of another chamber. The operation of supply and injection valves associated with the chambers is also synchronized, both with each other and with expansion and contraction of the chambers. In the embodiment described, two pumping chambers are defined within a common pressurizing cylinder, in which the chambers are separated by a piston. The piston is movable within the cylinder to determine and to synchronize expansion and contraction of the chambers.

An injection molding apparatus has a mold tool that is positioned around a field joint of a pipeline to define a mold cavity. Two or more pumping chambers communicate with the mold tool. Each chamber is expansible to draw in molten polymer and contractible to drive the polymer into the mold cavity. Expansion of one chamber is synchronized with contraction of another chamber. The operation of supply and injection valves associated with the chambers is also synchronized, both with each other and with expansion and contraction of the chambers. In the embodiment described, two pumping chambers are defined within a common pressurizing cylinder, in which the chambers are separated by a piston. The piston is movable within the cylinder to determine and to synchronize expansion and contraction of the chambers.

An injection molding apparatus comprises a support base and a mold carrier removably mounted to the support base. The mold carrier includes a mounting plate with attachment features for engaging the support base. A mold with two mold plates is slidably mounted to the mounting 5 plate. A clamp is operable to move the plates between open and closed positions. In the closed position, the plates abut one another. In the open position, the plates are spaced apart for removing molded articles.

A plasticizing device that plasticizes a solid material includes a drive motor, a screw rotated by the drive motor along a rotation axis of the drive motor and having a groove forming surface on which a groove is formed, a barrel having a facing surface facing the groove forming surface and provided with a communication hole in a central portion thereof, and a heating unit configured to heat at least one of the screw and the barrel. A first facing region and a second facing region that is closer to the central portion than the first facing region are provided between the groove forming surface and the facing surface. A second gap between the groove forming surface and the facing surface in the second facing region is larger than a first gap between the groove forming surface and the facing surface in the first facing region.

The invention relates to an apparatus (1) for injection molding, said apparatus comprising -a mold cavity member (20) having a mold cavity (22), -a melt channel, -an injection chamber (16) and -an injection gate having an injection gate hole (24). The apparatus further comprises a movable injection sleeve (10) and furthermore -the melt channel is configured for providing a flow of molten material from a source of molten material to an injection chamber (16), -the apparatus (1) is configured for transferring the molten material from the injection chamber (16) to the mold cavity (22) via said injection gate hole (24), said injection gate being controllable by a forward part of a movable filling valve (6), and -the injection chamber (16) has a volume that is controllable by movement of the movable injection sleeve (10). The invention further relates to a method of injection molding.

A method for increasing the injection speed of a melted plastic injection device for injecting said melted plastic into a molding cavity (51), said injection device comprising: a first cylinder (1) provided with a tubular casing (2) defining a first inner diameter d.sub.1, and a first piston (3) slidable inside said tubular casing (2), adapted to be loaded with melted plastic and to inject said melted plastic toward the molding cavity (51); a second cylinder (21) constrained to the first cylinder (1) and provided with a second piston (23) which rod (24) is connected to the first piston (3) and is adapted to actuate said first cylinder (1) during an injection operation; the method comprising the steps of: releasing second cylinder (21) and first cylinder (1) by extracting the first piston (3) from the tubular casing (2); coaxially inserting a tubular body (12), defining a second inner diameter d.sub.3 which is smaller than the first inner diameter d.sub.1, into the tubular casing (2); disconnecting the first piston (3) from the rod (24); connecting a third piston (13) to the rod (24), said third piston (13) being sized to slide inside said tubular body (12); constraining second cylinder (21) and first cylinder (1) by inserting the third piston (3) into the tubular casing (2).