Abstract: Disclosed herein, amongst other things, is a control structure for a molding system (900). The control structure includes a controller (106, 934) and a valve actuator (104) for positioning a valve member (102) of a valve (101) for regulating flow of molding material in the molding system (900), wherein the controller (106, 934) is configured to monitor an operating parameter of the valve actuator (104) for indirectly appreciating an indication of a molding parameter of the molding system (900).

Abstract: An improved take-off device for an injection molding machine that includes an extensible sleeve for extending a suction channel during transfer of parts from the mold core assembly to the take-off device, the tube being retractable after the parts have been transferred.

Abstract: Apparatus for coinjecting a plurality of thermoplastic materials to mold an article having a layered wall structure using thermoplastic material having different optimum processing temperatures including the maintenance of the optimum temperatures in flow paths individual to each material from its source to a mold cavity.

Abstract: In order to mold tamperproof bottle closures or other plastic articles having a threaded cap frangibly connected with an adjoining skirt which has a number of internal projections or spurs inclined in a transverse plane at approximately identical acute angles to its inner peripheral surface, a male mold portion has a core in the form of a stepped cylinder with a small-diameter part rotatably enveloped by a sleeve flush with an adjoining large-diameter part jointly defining an annular gap with a surrounding shell. The sleeve has recesses in the shape of undercut slots forming the internal projections of a skirt molded in that gap; after sufficient hardening, the shell is rotated to extract these projections from their recesses with resulting radial expansion of the skirt into an adjoining space from which the shell has been axially withdrawn.

Abstract: An intermediate platen carrying two inner plates of a stack mold, coacting with two outer plates respectively mounted on a stationary and a movable platen of an injection-molding machine which are interconnected by a set of four tie bars, has a pair of forwardly extending and a pair of rearwardly extending outrigger arms terminating in respective shoes which slide on two of the tie bars, preferably the lower ones.

Abstract: One of two relatively movable platens of an injection-molding machine carries a housing in which a cylindrical cam with a generally helicoidal groove is rotatably lodged, the cam being rigid with a shaft disposed parallel to the direction of platen motion. A cam follower on the inner surface of that housing engages in the helicoidal groove whereby the shaft is rotated during relative reciprocation of the platens; a hub idling on the opposite shaft end, supported by a control box on the other platen, can be positively coupled to the shaft by a clutch in this box so as to rotate therewith. An elbow coupled with that hub, directly or through a carriage having a rack in mesh with a gear fixed to the hub, supports a pick-up head which in the engaged state of the clutch enters between two separated mold portions respectively carried by the platens for extracting a freshly molded workpiece from the mold or, possibly, placing an externally supplied insert in an empty mold cavity.

Abstract: A four-sided turret interposed between a fixed and a movable platen of an injection-molding machine, mounted on a carriage which is slidable in the direction of platen motion, is rotatable about an axis perpendicular to that direction into four operative positions spaced 90.degree. apart. In each of these positions, in which one or more cores carried on one of its faces enter respective cavities of a confronting mold plate on the fixed platen while a corresponding core or cores on an opposite face are received in a companion plate on the movable platen, the turret is positively indexed by two aligned pins on these plates which enter respective bores in the turret upon closure of the mold; such closure, conversely, is prevented by the pins until the turret is in the proper position.

Abstract: A plasticizing screw of an injection-molding machine, axially movable in an extruder barrel, is driven by a tubular input shaft via a splined quill partly retractable into the shaft with which the quill is coupled through an internally and externally splined bushing. Another such bushing is removably seated, for possible replacement by a similar bushing of different inner diameter, in an internally splined cup-shaped head of the quill and engages the splined rear end of the screw. The quill head rests via a thrust bearing against the front end of a nonrotatable tubular piston coaxially surrounding the quill and entering by its rear end an annular cylinder which is hydraulically connected with a pressure accumulator including a gas cushion. The accumulator creates a back pressure by which molding material, plasticized by the screw during the preceding phase in which the screw was repressed into a rear position, is introduced via a check valve into a shooting pot alongside the extruder barrel.

Abstract: A take-off plate, mounted near one of two relatively movable mold portions and insertable therebetween to remove freshly molded workpieces, enters a slot of a guide block rigid with the same mold portion upon moving from a retracted to an inserted position, the guide block also having a bore intersecting the slot and extending in the direction of mold motion. A pin on the other mold portion traverses the bore upon closure of the mold to prevent untimely insertion of the take-off plate; conversely, the take-off plate in its inserted position obstructs the bore to prevent premature mold closure.

Abstract: An injection mold with a female mold portion and a male mold portion has a locking ring with beveled inner centering surfaces which, in a mold-closed position, embrace respective outer centering surfaces of the two mold portions for holding them precisely aligned for molding a thin-walled cup between a tapered core of the male portion and a cavity wall of the female portion. The core is surrounded by a stripper ring which rests on an internal shoulder of the locking ring concentric therewith and is entrainable with the latter by a stripper plate when the mold is opened. The two concentric rings may be interconnected by screws, by a snap ring, or by radially extending pins lodged in coplanar bores of the locking ring and engaging in a peripheral groove of the stripper ring, these pins having flattened faces or eccentric ends held in contact with one of the groove walls by mounting bolts which traverse the channels and secure the locking ring to the stripper plate.

Abstract: A clamping mechanism, effective to press a movable platen against a fixed platen in a terminal phase of a mold-closing stroke of an injection-molding machine, comprises a series of coaxial annular pistons received with progressively larger clearances in respective inner peripheral grooves of a stationary housing linked by tie rods with the fixed platen. The pistons, which can be interconnected by elastic bolts, bear upon a mounting frame, slidable along the tie rods, supporting a pair of laterally withdrawable shutters which in their retracted position give passage to a tubular thrust member coaxially surrounding a plunger secured to that thrust member and to the movable platen. The opposite end of the plunger carries a piston head received, within the housing, in a central driving cylinder to which hydraulic fluid can be admitted from either end for advancing or retracting the movable platen in a mold-closing or a mold-opening stroke.