Abstract: An apparatus for injection molding using a stack mold comprising first and second mold assemblies interposed between a movable platen and a stationary platen comprises at least one centering device for coupling movement of the movable platen to intermediate mold members of the mold assemblies, the centering device comprising first and second helical gear mechanisms and a transmission coupling rotation of helical gear segments of the first and second helical gear mechanisms. Effective pitch of the helical gear mechanisms and the ratio of rotation coupled by the transmission are chosen to maintain the intermediate mold members centered in or offset from center in the separation between the movable platen and stationary platen.

Abstract: A rack and pinion centering device for stack molding has at least one attachment device comprising a base attached to a mold member and at least one releasable clamp member, an end of a rack of a centering device being interposed between the base and the releasable clamp member and being held in a longitudinal location relative to the base within a range of adjustment by the releasable clamp members, whereby the longitudinal location of the rack relative to the mold member is determined within the range of adjustment. The attachment device permitting machining of mold members for attachment of centering devices while a mold assembly is removed from the clamp unit of a molding machine.

Abstract: A rack and pinion centering device for stack molding has at least one attachment device comprising a base attached to a mold member and at least one releasable clamp member, an end of a rack of a centering device being interposed between the base and the releasable clamp member and being held in a longitudinal location relative to the base within a range of adjustment by the releasable clamp members, whereby the longitudinal location of the rack relative to the mold member is determined within the range of adjustment. The attachment device permitting machining of mold members for attachment of centering devices while a mold assembly is removed from the clamp unit of a molding machine.

Abstract: An apparatus for injection molding using a stack mold comprising first and second mold assemblies interposed between a movable platen and a stationary platen comprises at least one centering device for coupling movement of the movable platen to intermediate mold members of the mold assemblies, the centering device comprising first and second helical gear mechanisms and a transmission coupling rotation of helical gear segments of the first and second helical gear mechanisms. Effective pitch of the helical gear mechanisms and the ratio of rotation coupled by the transmission are chosen to maintain the intermediate mold members centered in or offset from center in the separation between the movable platen and stationary platen.

Abstract: A sprue bar nozzle assembly for controlling flow of melt through conduits of a mold assembly for injection molding comprises a sprue bar extension and nozzle, the sprue bar extension comprising means for adjusting the overall length of the sprue bar nozzle assembly and the nozzle comprising a nose comprising a seating surface for mating engagement with a mating surface of a mating segment of a melt conveying conduit and a slide valve, an open position of the slide valve permitting melt to flow through the sprue bar nozzle assembly and a closed position preventing melt from flowing through the sprue bar nozzle assembly, the slide valve being biased to a closed position by a biasing means and being driven to the open position by forces applied to the nose of the nozzle as a result of closure of an associated mold assembly.

Abstract: An apparatus for conducting melt in stack mold arrangements comprises at least one tubular body having a passage there through for conveying melt, an interface member mounted to at least one tubular body at a terminus of the passage for conducting melt between the tubular body and a mating mold member engaged by the interface member, and a length adjusting device interposed between the interface member and the tubular body and having a wedge member and means for setting the transverse position of the wedge member relative to the longitudinal axis of the tubular body whereby the overall length of the combined tubular body and interface member is established. A sprue bar assembly comprises a sprue bar segment, a nozzle and a length adjusting device interposed between the nozzle and the sprue bar segment having an adjustable wedge member for establishing the overall length of the sprue bar assembly.

Abstract: An apparatus for conducting melt in stack mold arrangements comprises at least one tubular body having a passage there through for conveying melt, an interface member mounted to at least one tubular body at a terminus of the passage for conducting melt between the tubular body and a mating mold member engaged by the interface member, and a length adjusting device interposed between the interface member and the tubular body and having a wedge member and means for setting the transverse position of the wedge member relative to the longitudinal axis of the tubular body whereby the overall length of the combined tubular body and interface member is established. A sprue bar assembly comprises a sprue bar segment, a nozzle and a length adjusting device interposed between the nozzle and the sprue bar segment having an adjustable wedge member for establishing the overall length of the sprue bar assembly.

Abstract: A nozzle controls flow of melt in injection molding equipment by passive actuation with opening and closing of a mold assembly. The nozzle comprises a valve pin having a pin passage therethrough movably supported within a nozzle passage and a contact arm transverse to and extending beyond the nozzle passage, the valve pin sealingly engaging the nozzle passage. Biasing means biases the valve pin to a closed position preventing passage of melt through the nozzle. The contact arm effects movement of the valve pin to an open position when closing of the mold assembly exerts a force on the contact arm to overcome the biasing means. A mold arrangement of plural mold assemblies comprises pairs of nozzles of the invention to control flow of melt through mating conduit segments between an injection unit and at least one mold assembly, the nozzles arranged and configured for seating engagement with abutment of the conduit segments.

Abstract: A flow nozzle (10) that conveys plastic melt from an injection unit of a molding machine to a mold cavity (72) has an improved, removable seal design. The nozzle body (12) is designed to threadedly receive a nozzle tip (24) that includes an outlet (30) that communicates with the mold cavity. A thin-wall, cylindrical seal ring (40) includes a compression portion that is received between the nozzle body and nozzle tip and is compressed to create a seal between these two elements when the tip is assembled to the nozzle body. The seal ring further includes a sealing portion (50) that encircles the nozzle tip and has an outer diameter slightly larger than the outer diameter of the nozzle body.

Abstract: A latching device (20) for a mold assembly (10) uses a cam action to hold the “A” side plate against the hot runner system/nozzle plate (18) during operation. Preferably, a latch (20) is provided on each side of the mold to effectively hold the “A” side plate against the nozzle plate (18) during the high pressure injection of plastic melt. For purposes of a mold insert change, each latch (20) is rotated to release the “A” side plate from the nozzle plate (18), and hold the “A” side plate against the “B” side plate. This enables the “A” (12) and “B” (14) portions of the mold assembly to be moved away from the nozzle plate (18), thereby avoiding interference of the hot runner nozzles and “A” side insert and enabling quick mold insert change.

Abstract: A thermal expansion compensation support and method are used in a hot runner injection mold for maintaining liquid-tight relationships between parts that define a flow passageway. The support includes an annular housing having an annular recess that receives a spring, such as a Belleville washer, and a cover that overlies the annular recess in the housing. The housing and the cover are spring biased from each other to maintain a pressure force on the surfaces that are in contact with the outer faces of each of the cover and of the annular housing. The support imparts a holding force on the several parts of the machine that define the molding material flow passageway to prevent leakage. The method involves holding the parts together at a first holding force level for an initial portion of a warm-up temperature range and holding the parts together at a second holding force level for the remainder of the temperature range.

Abstract: A flow nozzle (10) that conveys plastic melt from an injection unit of a molding machine to a mold cavity (72) has an improved, removable seal design. The nozzle body (12) is designed to threadedly receive a nozzle tip (24) that includes an outlet (30) that communicates with the mold cavity. A thin-wall, cylindrical seal ring (40) includes a compression portion that is received between the nozzle body and nozzle tip and is compressed to create a seal between these two elements when the tip is assembled to the nozzle body. The seal ring further includes a sealing portion (50) that encircles the nozzle tip and has an outer diameter slightly larger than the outer diameter of the nozzle body.

Abstract: A latching device (20) for a mold assembly (10) uses a cam action to hold the “A” side plate against the hot runner system/nozzle plate (18) during operation. Preferably, a latch (20) is provided on each side of the mold to effectively hold the “A” side plate against the nozzle plate (18) during the high pressure injection of plastic melt. For purposes of a mold insert change, each latch (20) is rotated to release the “A” side plate from the nozzle plate (18), and hold the “A” side plate against the “B” side plate. This enables the “A” (12) and “B” (14) portions of the mold assembly to be moved away from the nozzle plate (18), thereby avoiding interference of the hot runner nozzles and “A” side insert and enabling quick mold insert change.

Abstract: A molding nozzle controls the flow of material from a source of plastic melt to an outlet that communicates with a gate to a mold cavity. The nozzle contains a valve pin that includes a guide section and a valve end, and is movable toward and away from the gate to open and close the gate selectively. The valve pin is guided for movement by guide surfaces on inwardly-extending vanes within the nozzle, such that the guide surfaces engage the guide section of the valve pin. The valve end of the valve pin has a smaller diameter than that of the guide section, so that the valve section is free-floating to allow annular flow in the guide surface region to minimize the likelihood of formation of flow lines in the molded part.

Abstract: A thermal expansion compensation support and method are used in a hot runner injection mold for maintaining liquid-tight relationships between parts that define a flow passageway. The support includes an annular housing having an annular recess that receives a spring, such as a Belleville washer, and a cover that overlies the annular recess in the housing. The housing and the cover are spring biased from each other to maintain a pressure force on the surfaces that are in contact with the outer faces of each of the cover and of the annular housing. The support imparts a holding force on the several parts of the machine that define the molding material flow passageway to prevent leakage. The method involves holding the parts together at a first holding force level for an initial portion of a warm-up temperature range and holding the parts together at a second holding force level for the remainder of the temperature range.

Abstract: A thermal expansion compensation support and method are used in a hot runner injection mold for maintaining liquid-tight relationships between parts that define a flow passageway. The support includes an annular housing having an annular recess that receives a spring, such as a Belleville washer, and a cover that overlies the annular recess in the housing. The housing and the cover are spring biased from each other to maintain a pressure force on the surfaces that are in contact with the outer faces of each of the cover and of the annular housing. The support imparts a holding force on the several parts of the machine that define the molding material flow passageway to prevent leakage. The method involves holding the parts together at a first holding force level for an initial portion of a warm-up temperature range and holding the parts together at a second holding force level for the remainder of the temperature range.