Abstract: A blow molding assembly for thermoplastic resins, used, for example, for the manufacture of bottles wherein parisons are heated in an oven and then transported to a mold station where they are biaxially oriented and blown. The invention is particularly concerned with a transport system operating from the oven to the molds, wherein the spacing between the various parisons being transported by means of picker means can be adjusted so that the parisons may be introduced into molds at a spacing different from the spacing of the parisons in their travel through the oven. The transport system includes means for picking off parisons from a conveyor with a predetermined spacing and means for spreading or narrowing the spacing to match the centerline-to-centerline spacing of the molds.

Abstract: An injection molding machine having a barrel and a reciprocating and rotatable screw disposed therein. A combination heat transfer and stratification device is disposed between the screw and the outlet of the barrel. The device includes a generally tubular portion having radially outwardly extending ribs. The ribs are in contact with the inner wall of the barrel. Heating means supply heat to the portion of the barrel containing the device and heat is transmitted through the rib portions. A process is disclosed whereby plastic is partially melted in the screw section and then stratified for final melting and thereby reduces mixing to provide a mottled appearance or plastic parts containing long fine filaments such as fine wires.

Abstract: A screw for use in the bore of an extruder barrel of a molding machine thermo-plastics material feeder has an intermediate section of circumferentially interrupted helical flights or screw threads with inclined ramps on the leading ends of the interrupted flights or threads effective to flatten unmelted lumps of plastics material for increasing the surface area thereof to enhance heat transfer for expediting melting of the material. The tapered ramps are preferably longitudinally grooved forming shallow pockets gripping the plastics material and shearing the lumps as they are wedged between the ramps and bore of the extruder barrel. The peripheries of the flights or screw threads are spaced from the bore of the extruder barrel to define extrusion gaps therebetween with the gaps diminishing in thickness from the inlet to the outlet ends of the screw section or zone.

Abstract: A single screw injection device or extruder sequentially injects skin and foamed plastics melts into a mold to produce structural skin covered foam molded parts free from swirl marks. A single extrusion screw or plasticator selectively feeds, compresses and meters a plastics melt to a first injector for skin melt injection or to a gas injection well where it meters gas flow into the melt, mixes the gas and melt to form a foam and feeds the foam to a second injector for foam melt injection into the mold. A valve controls the flow of the plastics melt and the foamed plastics melt to a single injection nozzle for discharge into the mold. In sandwich molding, a small amount of the unfoamed melt is first injected to form the skin for the molded article and then the valve is shifted to connect the nozzle with the foamed melt from the screw whereupon the injector forces the foamed melt through the nozzle into the mold to overlie the skin melt.

Abstract: A valve controlled multiple port nozzle device is provided for co-injection molding to sequentially and simultaneously feed a plurality of plastics material melts into a mold. The nozzle device is especially adapted for initially feeding a skin melt followed by a simultaneous feeding of the skin melt and core or foamed melt and then followed by a final skin melt feed into a mold for producing a molded article with a core surrounded by a complete skin. The nozzle device has a single needle or pin valve controlling flow through the nozzle orifice and sequentially opening the orifice to flow from two inlet ports. The needle or pin has a blind bore selectively communicating with one of the ports as it is retracted from the nozzle orifice and spacers are provided to vary the gap between the needle valve tip and the orifice relative to the opening of the blind bore to its port.

Abstract: A blow molding assembly for thermoplastic resins, used, for example, for the manufacture of bottles wherein parisons are heated in an oven and then transported to a mold station where they are biaxially oriented and blown. The invention is particularly concerned with a transport system operating from the oven to the molds, wherein the spacing between the various parisons being transported by means of picker means can be adjusted so that the parisons may be introduced into molds at a spacing different from the spacing of the parisons in their travel through the oven. The transport system includes means for picking off parisons from a conveyor with a predetermined spacing and means for spreading or narrowing the spacing to match the centerline-to-centerline spacing of the molds.

Abstract: An improvement is provided for plastic molding machinery of the type comprising a plastic melt injection apparatus and a mold. A shut-off valve which provides communication between the injection apparatus and the mold, includes a single elongate passageway and an elongate shut-off piston oriented generally parallel to the flow path and mounted in the passageway by a housing, which housing is supported by a single, streamlined leg so that the plastic melt flows therethrough in a single, undivided flow path. The melt flow path, as defined by the passageway and housing mounted therein has a generally circular transverse cross-section at an upstream station and a generally U-shaped transverse cross-section at a station downstream of the circular station. An aspect of the improvement is a plug-shaped tip formed integrally on the downstream end of the piston for expelling residue and cleaning the outlet port especially in structural foam molding applications.

Abstract: An oven for heating tubular parisons to a target or orientation temperature. A first plenum on one side of the oven and a second plenum on the opposite side of the oven, both exhaust to a common chamber disposed therebetween. The parisons are heated by a high velocity fluid above the target temperature in the zone defined by the first plenum and the chamber and the parisons are tempered by a lower velocity fluid at the target temperature in the zone defined by the second plenum and the chamber.

Abstract: An injection molding machine having a barrel and a reciprocating and rotatable screw disposed therein. A combination heat transfer and stratification device is disposed between the screw and the outlet of the barrel. The device includes a generally tubular portion having radially inwardly extending ribs. The ribs are in contact with the inner wall of the barrel. Heating means supply heat to the portion of the barrel containing the device and heat is transmitted through the rib portions.

Abstract: A screw for use in a thermoplastic extruder. A plurality of recessed pockets and/or raised lobes are in the screw shaft and these operate as the shaft is rotated to constantly shift the melted and unmelted portions of the plastic resin radially inwardly and outwardly within a pitch length of the screw inside the extruder to quickly and uniformly mix the plastic into a homogeneous melt.

Abstract: An apparatus for transferring parisons from an oven to a blow mold has the capability of straightening up tilted parisons and gripping them uniformly without flattening the ends. The apparatus includes a gripper with jaws which open wide when opened, thereby providing an entry space between the jaws for a tilted parison as well as an upright parison and which in the closed position form an essentially complete circle about the parison to uniformly grip the same in cooperation with a push piece which moves into the open end of the parison.

Abstract: An oven for heating tubular parisons has a conveyor passing therethrough with parison holders rotatably mounted thereon for vertically supporting the parisons. To assure uniform heating of the parisons around their circumferences, the parison holders are rotated about their axes. For this purpose teeth projecting out from the parison holders engage a group of stiff brush-like bristles, arranged either as tufts or as a continuous stand thereof, fixedly arranged alongside the conveyor path at a distance therefrom to be engaged by the said teeth.

Abstract: An oven for uniformly heating parisons to a target temperature, including a movable wall portion which is raised and lowered to accommodate parisons of various axial lengths. The movable portion maintains a confined flow path to minimize stray air currents.

Abstract: A cascade type dynamic mixer for extrusion of plastic comprises extruder screw means to advance a thermoplastic resin material through a hollow barrel, and having a mixing section along a length thereof provided with a plurality of encircling barrier rings in axially spaced relation therealong. The rings have localized high shear cascade areas which are graduated to pass progressively smaller size particles along the mixing section. On each ring, undulations provide alternating plastic advancing and reversing flight lengths, the shear areas being on the reversing flight lengths which are shallower than the plastic advancing flight lengths and progressively higher in each ring downstream along the mixing section.

Abstract: Redistributive mixing is effected in an extruder wherein the extruder screw advances thermoplastic material toward and through transfer grooves in a corotative torpedo. The torpedo grooves progressively diminish in cross sectional flow area from inlet ends at the upstream end of the torpedo toward downstream ends running out adjacent to the torpedo tip. Feeder grooves in a complementary passage wall of a stationary discharge head adapter in which the torpedo operates, receive the thermoplastic material transferred and propelled with redistributive mixing action from the torpedo grooves. The passage wall grooves have upstream entry ends aligned with the upstream ends of the torpedo grooves and extend therefrom in progressively increasing cross sectional flow area to downstream ends feeding toward an outlet.

Abstract: A device for positively positioning a tubular workpiece on a carrier, and in particular for positioning a tubular parison on a carrier of a conveyor within a parison heating oven. The parisons are engaged by a cam operated positioning cap which exerts a downward force on the top of the parison to position the parison on its carrier member.

Abstract: An oven for heating tubular parisons to a target or orientation temperature. A first plenum on one side of the oven and a second plenum on the opposite side of the oven, both exhaust to a common chamber disposed therebetween. The parisons are heated by a high velocity fluid above the target temperature in the zone defined by the first plenum and the chamber and the parisons are tempered by a lower velocity fluid at the target temperature in the zone defined by the second plenum and the chamber.