An apparatus for injecting a molten plastic material into a mold is described. The apparatus includes a heated manifold (manifold) with channels to distribute molten material inside it, and a heated injector, to inject molten material to the mold cavity, equipped with a translatable shutter to regulate the flow of the injected molten material.

An actuator is attached to the manifold to receive molten material from it to send to the injector and move the shutter. The actuator includes a piston connected to the plug, and a first conduit to bring a pressurized fluid from the outside to the piston. A plate includes a second internal conduit to bring pressurized fluid to the injector, where a gap separates the plate and the actuator.

A connecting member is mounted to cross the gap and carry pressurized fluid from the plate to the actuator.

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.

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.

An injection molding apparatus including an actuator interconnected to a rod or valve pin having a smooth continuous cylindrical outer surface and one or more discontinuous or relieved or relieved portions formed as discontinuities in the cylindrical outer surface and adapted to be disposed within a fluid flow channel, the one or more discontinuous or relieved portions being configured and arranged along the axial length of the pin or rod such that the flow of injection fluid over or past the one or more discontinuous or relieved portions is modified to flow at substantially different rates or velocities or in substantially different flow patterns relative to rate or velocity or pattern of flow of injection fluid over or past the smooth continuous cylindrical outer surface.

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.

The disclosure relates to an injection nozzle (1) suitable for injection molding of thermoplastic materials, in particular polyolefin materials, the injection nozzle (1) comprising a housing (2) comprising a sleeve-shaped rear section (3) and a thereto coaxially arranged sleeve-shaped front section (4) surrounding a central passage (5) extending in an axial direction (z) forming part of a melt channel (6). In the central passage (5) a needle (7) is arranged movable in the axial direction (z) between a retracted open position and an extended closed position in which a gate (8) at a tip (9) of the front section (4) is closed by a front end (10) of the needle (7) in a sealing manner. A spacer (11) is arranged between the rear section (3) and the front section (4) defining a total length of the housing (2) in the axial direction (z).

An apparatus for injection molding of fluid plastic materials includes a mold, a hot runner distributor of the fluid plastic material, at least one injector, and an actuator for controlling the opening and closing of the injector, including a jack whose cooling is performed by means of an air flow.

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).

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).