Abstract: Active decompression to prevent melt drool from a mold (12, 14) or runner system (20) is achieved through the selective coupling and de-coupling of an injection piston (34) to a plunger (38). Following successive injection (FIG. 5a) and hold phases (FIG. 5b) of an injection molding process (FIG. 5), the runner and channel system is partially de-compressed (FIG. 5c) by drawing back together, over a short distance, the plunger (38) and the injection pressure (34) as one unit. The injection piston is then mechanically de-coupled from the plunger (FIG. 5e), with the injection piston (34) withdrawn to essentially its final shot position, but minus a customary packing distance (?). Plastic melt (100), extruded into a shooting pot (28) positioned in front of the plunger (38), is permitted to push the plunger backwards, but now with minimal work expenditure. When the plunger again contacts (FIG. 5f) the injection piston (34), melt pressure now causes both units to be moved back to reach a final shot size volume.

Abstract: An injection molding machine conventionally includes a hydraulic circuit that communicates energy from a first motor. The hydraulic circuit typically includes pumps that regulate, in a conventional fashion, the flow of hydraulic fluid to control molding sub-assembles and functions, such as clamp up, stroke and injection. Additionally and conventionally, a dedicated electric drive is coupled to an extruder to effect rotation and operation thereof. According to the invention, the hydraulic circuit is extended to include a hydraulic motor drive whose operation is to rotate the extruder, thereby permitting the dedicated electric drive and its associated frequency and power control circuitry to be eliminated.

Abstract: Active decompression to prevent melt drool from a mold (12, 14) or runner system (20) is achieved through the selective coupling and de-coupling of an injection piston (34) to a plunger (38). Following successive injection (FIG. 5a) and hold phases (FIG. 5b) of an injection molding process (FIG. 5), the runner and channel system is partially de-compressed (FIG. 5c) by drawing back together, over a short distance, the plunger (38) and the injection pressure (34) as one unit. The injection piston is then mechanically de-coupled from the plunger (FIG. 5e), with the injection piston (34) withdrawn to essentially its final shot position, but minus a customary packing distance (6). Plastic melt (100), extruded into a shooting pot (28) positioned in front of the plunger (38), is permitted to push the plunger backwards, but now with minimal work expenditure. When the plunger again contacts (FIG. 5f) the injection piston (34), melt pressure now causes both units to be moved back to reach a final shot size volume.

Abstract: In a molding machine (130), exemplified in FIG. 4, lateral and angled offsetting of a twin screw extruder (26) from a shooting pot assembly (24) permits shortening of a transfer channel (56). To additionally reduce shear effects arising from melt residence time a nozzle adaptor (52), the transfer channel (56) is located within a hollow cone (102) of a platen (90), the hollow cone (102) typically formed by an arch-shaped intermediate support structure (154) coupling together front (150) and rear (152) walls of the platen (90). To address bulk material removal brought about by the introduction of a barrel head, transfer channel (56) and extruder barrel tip within the hollow cone (102), reinforcement of an upper region of the rear wall (152) of the platen (90) is accomplished using a cross-member (160, 164).

Abstract: A platen (90), exemplified in FIG. 7, has a cone-based configuration in which a rear wall (152) provides access, via a hole (98, 100, 104), to a hollow recess (102) defined by the cone. The hole permits both housing of a transfer channel (56) within the hollow recess (102) and relative angled entry of an extruder barrel head and head end of a shooting pot (23, 24) that couple to the transfer channel (56). The platen (90) includes a reinforcing cross-member (160, 164) located above the hole (98, 100, 104), which cross-member produces an outwardly projecting step (163) near a top surface of the platen (90). The projecting step (163) substantially corresponds to a width of the hollow recess (102). The cross member (160) may thicken the rear wall (152) above the hole (100) by providing an inwardly extending flange (166). The platen (90) therefore retains sufficient strength, while accommodating for a lateral mounting displacement of the extruder (26) and shooting pot (23).

Abstract: A injection unit (10) of an injection system, including a shooting pot (12) having a shooting pot head (13) at one end, defining a melt chamber (14) therein; a melt inlet channel (16) for laterally bringing melt into the melt chamber (14); a plunger (26) arranged in the melt chamber (14), the plunger (26) being linearly moveable from a retracted position into an extended position, so as to force melt accumulated in the melt chamber (14) through a melt outlet channel (20) arranged in said shooting pot head (13) into an injection mold; an annular melt passage (28) provided between the melt chamber (14) and the plunger (26), for allowing the melt to flow from the melt inlet channel (16) to an outlet end (18) of the melt chamber (14); and a melt distribution channel (30) for distributing the melt from the melt inlet channel (16) to the annular melt passage (28).