Abstract: A cooling device of an injection mold for an optical disk substrate reduces the chances of cavitation caused by a turbulent flow of passing cooling water, thus enabling a disk cavity plate to be cooled uniformly. A plurality of main arc-shaped passages, which have the same cross-sectional shape and which are concentrically arranged, are provided at a pitch "p" from the inner circumference on the rear surface of the disk cavity plate of the optical disk substrate injection mold. Further provided are a connecting arc-shaped passage having a radius of "p" which connects a first main arc-shaped passage having a radius of R.sub.1 with a second main arc-shaped passage having a radius of R.sub.

Abstract: A method for tempering an injection mold wherein in a recurrent cycle, the molten material is introduced under pressure into the mold recess of the injection mold, hardened and removed from the mold. Coolant or heating medium is supplied as a function of the deviation of the measured actual temperature from the desired command temperature. A plurality of flow control valves for the coolant or heating medium are preferably controlled via a measuring sensor. The three-dimensional quantitative distribution of coolant as needed is ascertained empirically or by computer with respect to the particular mold and the runners provided in the mold for the coolant or heating medium, and at least one specific time in the cycle period a comparison is made between the command temperature and the actual temperature of the one measuring sensor.

Abstract: The present relates to an apparatus for molding plastic parts which includes a cavity insert and a core insert wherein each insert has an open area on the shell or back side thereof. A device for circulating fluid through each chamber cools the inserts. In one preferred embodiment, the cavity and core inserts are made using a mold having a ceramic formulation including generally uniform size aggregate materials and carbon fibers. In certain embodiments, the apparatus further includes pressure bearing devices for absorbing molding pressure during operation of the molding apparatus.

Abstract: A method for controlling the temperature of injection molding machines using cross-linking polymers and molding die units using plastics. Each unit is equipped with at least one cooling channel for circulating a temperature controlling medium therethrough. The temperature of the exhausted medium is compared to a desired value and the circulation of the medium is adjusted accordingly. The method includes the steps of calculating the heat dissipation within a cycle and presetting the desired heat dissipation, prior to the start of temperature control. The temperature of the exhausted medium and the feed medium are continuously measured. The heat content value WRG of the unit is determined once the unit reaches thermal equilibrium. The value WRG is stored in a subsequent cycle as a desired value based on the difference between the temperature of the exhausted medium and the feed medium during a reference cycle.

Abstract: Apparatus for injection molding plastic articles includes a first mold base, a plurality of mold cavity units fixed to the first mold base, a second mold base, and a plurality of mold core units fixed to the second mold base in alignment with the mold cavity units fixed to the first mold base, the mold bases being reciprocally movable longitudinally with respect to each other, and a stripper plate, situated between the first and second mold bases and movable with respect to the second mold base, carrying a plurality of pairs of secondary mold elements, the secondary mold elements cooperating with the mold cavity-units and mold core units to define the surface of the plastic articles.

Abstract: An apparatus for molding polystyrene mold halves which are used, for subsequent molding of a soft contact lens. The apparatus is designed with superior heat conduction capacity so as to minimize the molding cycle time, while simultaneously producing uniformly precise and accurate optical quality surfaces. Molten polystyrene is provided via a hot runner system to a plurality of mold cavities. In a specific variation, the convex surface provides the optical quality surface to the concave surface of the mold half produced thereby. The structural element which defines the convex surface includes a hollow cylindrical bushing and a removable power insert mounted therein, which may be changed so that the prescription strength of the contact lens to be formed by the mold may be varied. In a first embodiment, the power insert includes only a convex surface at its operational end.

Abstract: The present invention relates to a modular fluid distribution block having particular utility in a cooling system for the mold of an injection molding machine. The fluid distribution block of the present invention is characterized by a housing having a plurality of ports in fluid communication with each other and a plurality of feet. The feet have three orthogonally arranged bores machined therein to allow the fluid distribution block to be connected to another fluid distribution block, a plate for closing off a port and/or a fitting for allowing the fluid distribution block to be connected to another component such as a flexible hose. The fluid distribution block is preferably formed from a corrosive resistant material to avoid the problem of scaling. The manner in which the fluid distribution block is incorporated into a system for providing a mold with cooling fluid is also described.

Abstract: A system and apparatus for injection molding articles of crystallizable polymeric materials in a substantially completely amorphous state is provided. The system includes (i) a mold defining an article formation cavity and an outer cavity connected by a gate, (ii) a melt transport mechanism including a bushing having a distal portion located in the outer cavity in close proximity to the gate inlet, and (iii) a source of molten material. The geometric configurations of the distal portion of the bushing, the inner portion of the outer cavity and the gate, and the relative locations of the distal end of the bushing and the inlet of the gate are each selected such that melt material may flow from the source through the melt transport mechanism and gate into the article formation cavity. The melt transport mechanism is maintained at a temperature above the characteristic crystal melt temperature of the polymeric material.

Abstract: A process and an apparatus (10) for the production of a plastic article of large area and small wall thickness, wherein the plastic material (90) is injected in the viscous condition into a mold cavity which is defined by a bottom mold portion (20) and a top mold portion (36). During the operation of injection of the viscous plastic material, which takes place through an inlet (76), the top mold portion (36), with the bottom mold portion (20), forms a pre-molding cavity (86) which is enlarged in a wedge shape starting from the inlet (76). During injection of the viscous plastic material (90) into the pre-molding cavity (86) or immediately after the injection operation, the bottom and top mold portions (20, 36) are moved relatively towards each other, forming the definitive mold cavity (78), so that the viscous plastic material is uniformly distributed in the diminishing mold cavity.

Abstract: The present invention is directed to a method and an apparatus for forming glass articles from molten glass involving differentially cooling a plunger for press forming glass articles in a cooperative forming mold. More specifically, the method involves introducing cooling fluid into an inlet cooling cavity located in the upper portion of the plunger and causing the cooling fluid to flow from the inlet cooling cavity into a cooling passage located along the periphery of the nose portion and thereafter to flow into a outlet cooling cavity located in the upper portion of the plunger and thereafter exhausting the spent cooling fluid from the plunger.

Abstract: An injection molding apparatus for a preform is disclosed, having an injection molding station (14) and a cooling and ejection station (16). In the injection molding station (14), neck cavity molds (60), injection core molds (50) and an injection cavity mold (42) are clamped and preforms (1) are injection molded. Thereafter, the injection cavity mold (42) is separated at a relatively high temperature. The preforms (1) are transferred to the cooling and ejection station (16) while being cooled by the injection core molds (50) and neck cavity molds (60). While the next preforms (1) are being injection molded in the injection molding station (14), in the cooling and ejection station (16) cooling of the preforms (1) continues. After cooling the preforms (1) to a temperature suitable for release, the injection core molds (50) are separated only through a stroke sufficient to allow a space to open between core pins (52) of the injection core molds 50 and the inner surface of the preforms (1).

Abstract: A method for runnerless injection molding of a synthetic resin, provided with a novel valve gate for performing intermittent temperature control to forcibly change the property of a molten or solidified resin material adjacent to the gate, capable of performing a precision molding operation without leaving an improper gate mark. The apparatus therefor comprises a runner 3 with a temperature maintaining means for storing a molten resin and forming an injection passage, a gate 1 in communication with a cavity 2 connected to the end of the runner 3, a valve pin 4 enclosed within the runner 3, and an intermittent temperature control assembly P.

Abstract: Injection molds suitable for use in injection molding, structural foam molding, low-pressure injection molding, and gas-assisted injection molding of plastic articles are described. The injection molds contain a thin metal layer contoured on its outer surface to the shape of the article to be molded, a rigid thermoset plastic material cast upon the inner surface of the metal layer and supporting the metal layer, and heat transfer elements cast within the plastic material and located adjacent to the metal layer to transfer heat for the metal layer and the plastic material. Preferably the thin metal layer is nickel, the plastic material is epoxy, and the heat transfer elements are metal chips and heat transfer tubing. The injection molds of the present invention can be prepared at considerable cost and time savings relative to conventional injection molds.

Abstract: The invention relates to a method of controlling the temperature of an injection mold, in particular for plastics and aluminium diecasting. The molten material being pressure-fed into the mold recess or the mold recesses of an injection mold by means of an extruder or the like in recurring cycles, cured therein, removed from the mold, and pressure-melted material being again supplied with the start of another cycle. A plurality of flow control valves are controlled by a sensor to provide an impulse or intermittent flow of the temperature control medium during each molding cycle at the same point in time as the previous cycle. The sensor compares a calculated temperature for a determined point in time of a molding cycle with the actual temperature of the molding cycle for that point in time and triggers the flow of temperature control medium for a set period of time to adjust the temperature of the molding cycle. This provides a more exact method of injection molding.

Abstract: In injection molding, a mold forms a wall member, which defines a cavity, by bringing together two mold halves. The cavity wall is formed by a specially machined cavity plate having built-in support columns, fins and ejector pins columns. The plate forms a passageway and in-out flow chambers on the opposite side from the cavity surface which completely surrounds the cavity where coolant or heating circulating carrier flows at high rates. The resulting flow of coolant/heating carrier at high rates can be controlled by special positioning of the flow chambers and creates added turbulence. The built-in support columns, fins and ejector pins also dramatically increase the area of contact of the flow carrier with the cavity plate. The design incorporates built-in support columns and fins which make possible a thinner cavity surface plate by adding strength and structural support to the cavity area.

Abstract: Improved optical disks for information storage and holographic imaging, and optical lenses and reflective optical elements are among the difficult-to-mold thermoplastic products which require precision replication of the molding surfaces, in micro detail. By heating (with circulating heat transfer fluids supplied by a hot side reservoir) these mold surfaces to a temperature setpoint sufficiently high to retard solidification and premature viscoelastic skinning of the molten thermoplastic injected into the mold cavity, superior quality molded surfaces can be formed by the plastic, which is then rapidly cooled to solidification (by circulating heat transfer fluids supplied from a cold side reservoir).

Abstract: Rapid cooling of molded workpieces such as PET parisons formed in an injection molding machine is provided by a receiver receiving molded workpieces upon ejection from the molding machine, the receiver being transported out of the molding machine to an adjacent position where a cooling head coupled to a source of cooling fluid such as liquid nitrogen directs the fluid toward the surfaces of each workpiece. The cooling head engages and is sealed to the receiver to inhibit the escape of cooling fluid into the atmosphere thereby reducing cost, environmental impact, etc. A cooling program control coupled to the cooling fluid source supplies a discontinuous flow cooling fluid from said source to contact the workpieces only when the cooling head is engaged with and sealed to the receiver. A vacuum unit withdraws cooling fluid from the receiver subsequent to contact between the workpieces and the cooling fluid. The cooling fluid can then recooled and recycled for reuse.

Abstract: An arrangement for charging a plurality of molds for processing plastic materials with at least two sources of fluid and for temperature regulating the molds. Each mold of the arrangement is provided with a feed inlet conduit to which a three-way valve is connected. The feed inlet conduit is also connected to the two sources of fluid and each mold further includes an outlet conduit with a thermostat valve. A distribution element is connected to the feed inlet conduit and to the two sources of fluid. The three-way valve is connected to least two sources of fluid. This three-way valve has an outlet which is connected to the distribution element. A heating element is connected in each inlet conduit of each mold. A temperature regulator is mounted in each outlet of each mold for each heating element. This temperature regulator is coacts with the thermostat valve which is mounted downstream of each temperature regulator in each outlet conduit of each mold.

Abstract: An apparatus of cooling and solidifying a preform involves introducing a preform in a heated state released from an injection mold into a cooling tube having a bottom opening and an upper opening through which cooling air flows from said bottom opening to said upper opening, said bottom opening being provided with a fan for cooling air, and inserting a cooling core into the preform to place the cooling core in close contact therewith, the preform being forcibly cooled from interior and exterior thereof by cooling air flowing in a turning state between the preform and the cooling tube and a coolant supplied to said cooling core.

Abstract: In a mold for producing injection molded parts, the supply conduits for supplying molten material to the mold cavity are heated by various heating devices. Temperature measuring devices are provided for determining the temperature at predetermined locations within the melt flow. For the purpose of controlling the various heating devices depending on the predetermined temperatures at the individual measuring points, there is removably fixed to the mold at least one regulating member which is electrically connected via an electrical connector socket with electrical conduits installed within the interior of the mold. The electrical conduits installed within the interior of the mold are lead to the various heating and temperature measuring devices. The regulating member can be connected via an external conduit with a data supply and indicator member. The regulating member as well as the data supply and indicator member are preferably equipped to store several programs.

Abstract: A method and apparatus of cooling and solidifying a preform involves: introducing a preform in a heated state released from an injection mold into a cooling tube having a bottom opening and an upper opening through which cooling air flows from the bottom opening to the upper opening, the bottom opening being provided with a fan for cooling air, and inserting a cooling core into the preform to place the cooling core in close contact therewith, the preform being forcibly cooled from interior and exterior thereof by cooling air flowing in a turning state between the preform and the cooling tube and a coolant supplied to the cooling core.

Abstract: A mold cavity, a molten plastic inlet conduit for communication therewith and a channel in the inlet conduit for conveying molten plastic to the mold cavity. Separate heating and cooling are provided in the inlet conduit adjacent the mold cavity to closely control the temperature of the molten plastic in the channel adjacent the mold cavity.

Abstract: The method is used to process a synthetic moulding compound which crystallizes within a specific temperature range. In order to prevent milkiness in the blank to be produced, the moulding compound is chilled. The method prevents such milkiness, at least in the gate area of the blank, by keeping all of the moulding compound, during the operating cycle, as far as the gate area, at a temperature which is above the temperature T.sub.CC below which the moulding compound begins to crystallize. A gate system, which may be used to carry out the method, uses, in the interior of the injection nozzle, a strongly heat conducting nozzle core, a strongly heat conducting area in the immediate vicinity of the gate opening, and a gap for heat insulation of the nozzle tip, the nozzle core and the moulded body.

Abstract: The temperatures of structural members of a plastic compression molding machine are controlled so that the socket-and-spigot gap between the dies is maintained at a constant size or so that changes in the socket-and-spigot gap between the dies is maintained below an allowable limit. Working oil for the lift cylinder is passed through passages in at least the bolster, the slide, and the frame. A temperature controller can include heat exchangers and/or flow-rate control valves to control the temperature and/or flow rate of the portion of the working oil to be circulated through the respective structural member.

Abstract: An injection molding machine and method in which a hot runner has heated nozzles and piston operated nozzles valves, the stems of the nozzle valves and the nozzle bushings have passages connected to the cylinders to carry cooling fluid to the cylinders to actuate the nozzle valves.

Abstract: Optimum sprue design requires suitably large cross-sectional area of the open aperture during mold filling and packing yet fast heat removal from the molten sprue during solidification. This is accomplished by a "hollow" sprue configuration, wherein an enlarged female sprue bushing cavity of large draft angles is axially aligned with a "spreader die" type of male member having a generally conical-tipped or parabolic-tipped torpedo shape, creating a cross-sectional open aperture consisting of an annular ring along at least partway up from the base to the tip. Both male and female may be fitted with internal mass-transport cooling. Since the cooling time of the sprue is directly proportional to the wall thickness of the molten plastic sprue being formed, and cooling time is further inversely proportional to the plastic/mold surface area, the resulting "hollow sprue" provides superior cooling without impaired fill and pack function.

Abstract: An injection mold apparatus has an injection mold which includes two mold halves incorporating thinwalled members to define a cavity therebetween. Before injecting plastic material into the cavity, the mold is heated to a temperature above the melting point of the plastic material by circulating a heat carrier flowing through a heating device. During injection of plastic material, the flow of heat carrier is stopped for maintaining the temperature of the mold and for supporting the thinwalled members. After completely filling the cavity, the mold is cooled down to a temperature below the freezing point of the plastic material by suitably circulating the heat carrier which now passes through a cooling device.

Abstract: An injection molding heated manifold having a melt passage with a longitudinal portion to convey melt from a molding machine to a number of different nozzles. The steel manifold has a pair of cooling bores extending parallel to and equally spaced on opposite sides of the longitudinal portion of the melt channel. A cooling fluid, such as air, flows through the cooling bores to quickly cool the manifold after the system is shut down to minimize deterioration of the melt in the melt channel. The air flows helically around spiral vanes which are mounted in the cooling bores to avoid temperature stratification along the melt passage.

Abstract: A device for the injection of a plastic material in a mold having an injection head with an injection face designed to be placed in contact with the mold feeder channel. The injection head has an injection chamber supplied with plastic material by a feeder conduit. The plastic material is injected from the injection chamber to the mold feeder channel by means of a clack-valve system. The device also has a support for the injection head and an injection rod.

Abstract: Process and apparatus for the manufacture of integral roller door structures of any desired length and width, and comprising longitudinally juxtaposed slats separated by integral hinge formations. Such a structure having slats of any desired length can be produced by a semi continuous moulding process in which a molten plastics material and a foaming agent are injected into a mould, the part of the structure so formed being allowed to solidify before removing the solidified structure partially from the mould, then closing mould about the remaining portion of the structure, thereafter moulding a further part of the structure within the mould onto the remaining portion of the previously moulded part and repeating the cycle as often as required.

Abstract: This mold tooling has a hot drop assembly operatively mounted in a bore formed therein which opens to a mold face. Heated plastic material is fed to a feed tube of the hot drop assembly and this material is heated at a temperature higher than the working temperature of the mold during its transit the face of the tool by electrically energized heater bands encircling the feed tube. The space between the heater bands and bore wall accommodates tubing through which a flow of chilled cooling air is injected. The temperature and amount of the cooling air may be regulated to match the heat energy discharged by the heating bands into the bore and to the body of the tooling. The flow of cooling air transmits heat energy out of the bore so that heat sensitive plastic materials being molded is not degraded by hot drop assembly heat energy that otherwise would be conducted by the tool body to the tool face.

Abstract: An injection molding multi-gate nozzle with a central portion having a central melt bore and a spiral electrical heating element integrally brazed in a channel in its outer surface. The nozzle has a number of elongated conductive probes spaced in a sleeve portion which extends around the central portion adjacent its forward end. Each probe extends in the sleeve portion a predetermined distance rearwardly along the central portion and projects from the sleeve portion a predetermined distance forwardly of the forward end of the central portion. Each conductive probe has a copper inner portion which picks up heat from the adjacent coils of the heating element and carries it forwardly to the projecting forward portion adjacent one of the gates. In addition to providing additional heat, this configuration with the forwardly projecting probes provides the mold with more structural strength and improved cooling.

Abstract: A process for tempering tools, for use on the form tools of extrusion forming machines. In the injection molding tools there are conduction circuits for a coolant which are connected to ducts for the inflow and backflow of the coolant. Valves (4) control the throughflow of the coolant. There are temperature sensors (5, 6) in the ducts for the inflow and backflow of the coolant. The temperature sensors (5, 6) are connected to a computer (7) which controls the opening and closing times of the valves (4) as a function of a nominal difference fed in between the inflow and backflow temperatures of the coolant. Advantageously, a temperature sensor (3) which is also connected to the computer (7) is provided on the form tool.

Abstract: A runnerless method for injecting and molding a synthetic resin through a gate wherein a molten resin is intermittently cooled to solidification using a cooling medium to close the door for every injecting and molding operation of a molten resin in the gate, and relates also to a novel runnerless apparatus for injecting and molding a synthetic resin provided with a metal mold mechanism composed of a plural number of component members, in which the passage for the molten resin including a runner, the gate, and a cavity are drilled, a cooling medium-employing intermittent cooling mechanism for intermittently cooling the gate thereby enabling solidification of the molten resin in the gate, a mechanism for continuously applying heat to the gate for melting an existing resin, and an injection mechanism.

Abstract: A moulding apparatus and a method for producing a food product from a food mixture/formulation having a heat sensitive binding agent are described. The apparatus has a component which includes a barrel with a nozzle on one end. A heater is associated with the nozzle to heat a food mixture/formulation which is to be fed under pressure therein to a preselected upper temperature and thus form a food paste. A differentially heated mould is associated with the nozzle to receive the food paste to be ejected therefrom and then to form a moulded food product from the food paste.

Abstract: This invention relates to an injection molding system having a number of nozzles conveying melt from an elongated manifold to a common cavity. In the preferred embodiment, each heated nozzle has a melt channel which is offset from a central valve pin bore for conveying the melt to the gate. The melt channel extends through a side portion of the nozzle which is bolted to the side surface of the manifold. The bolts provide a seal against leakage of the pressurized melt, while at the same time allow slight lateral movement between the manifold and the nozzle. This provides for thermal expansion of the manifold relative to the nozzle which is accurately located in a well in the core. The system is used for large cavities which require large flow volumes and avoids the difficulty of accurate machining of the large molds to provide sealing.

Abstract: For manufacturing articles of plastics, rubber or any other material a mold or die assembly comprising a mold or die base assembled from repetitive modular standard elements consisting of substantially "ready to use" interchangeable base plates is provided by the invention.The base plates are prefabricated by high-precision castings or galvanoplastics or any other similar high-precisious non-cutting method of manufacture.At least two of such base plates are, as mold or die plates, provided with a pre-determined number and arrangement of finished to sized, prefabricated cylindrical bores or piercings of any non-circular, mainly polygonal cross-section. Each of said bores or piercings is capable of fittingly receiving an interchangeable mold or die insert carrying the individually designed (negative) mold or die cavity surface for forming the particular article(s) to be manufactured.

Abstract: A cut-off nozzle system is mounted on the melt conduction duct of the center, sectioned mold clamping plate of an injection molding machine, in such a way that in addition to rapid accessibility of the individual parts of the nozzle system, the center, section mold clamping plate can be easily and quickly separated from the associated screw unit as required for the removal of the molded parts from the molds. The nozzle system has a spacing ring with a torpedo as well as a right-angled adapter and a cut-off nozzle, which parts are exchangeably joined with each other to form one rigid unit. With a high-speed clamping device, this unit is fastened on the movable center, sectioned mold clamping plate. For the upward removal of the molded parts, the screw unit is displaced sideways while the cut-off nozzle system remains mounted on the center mold clamping plate.

Abstract: A coupling device of the insertion or plug-in type for connecting lines which conduct flowing media, preferably pressurized fluids, to the mold halves of a molding tool in an injection molding machine. The coupling device includes a first coupling member, for example, a coupling nipple, mounted on an adapter plate of the injection molding machine and a second coupling member, for example, a coupling sleeve, mounted on a mold half of the molding tool. A locking device is used for fixing the two coupling members in an engaged position. The locking device is biased into its locking position by means of a spring and can be moved against the biasing force by means of an electromagnet from the locking position into a releasing position.

Abstract: There is provided an apparatus for the manufacture of plastic parts from thermoplastic, thermoset and/or elastomer material by injection molding or reaction injection molding. The apparatus includes a multi-station locking unit of horizontal or vertical configuration adapted to hold a number of molds, and an associated injection unit of the simultaneous injection of the molds. The apparatus further has a movable center mold clamping plate sectioned lengthwise relative to the locking direction, the two parts of the plate being kept together by a high-speed clamping device and having arranged between the parts a melt conduction system having one or a number of separate melt conduction rails. Each melt conduction rail is rigidly clamped at its face between the sectioned mold clamping plate lengthwise relative to the direction of flow of the melt.

Abstract: An apparatus is disclosed for encapsulating a plurality of electronic components, which are bonded to the conductors of a strip, within a mold. The apparatus has an injection unit made up of a plurality of plungers slidable in a carrier and controlled by hydraulic cylinders. The hydraulic cylinders apply pressure to the plungers, which have a heating element for heating the material to be injected. A sensor attached to each plunger senses when the material is sufficiently softened, at which point a driving mechanism drives the entire carrier toward the mold, causing the plungers to inject the material into the mold.

Abstract: In a small-sized and precision injection molding apparatus, a raw material supply means, a raw material plasticization means, an injection plunger means and a melted resin flow passage means are all together incorporated in a mold, thereby a substantial distance from the raw material up to a cavity becomes shorter. Thus, an overall construction of the injection molding apparatus becomes small-size and compact.

Abstract: A electric runner distributor heater for use in passageway of a mold into which a flow stream of fluid plastic material is introduced and which in turn communicates with a plurality of sprue orifices. The heater includes a metal casing having an exposed surface over which the fluid material is directed at an elevated temperature, a plurality of unsheathed electrical heating elements disposed in respective zones of the casing corresponding to the location of selected of the sprue orifices, heat transmitting material compacted in the bore of the casing and surrounding each heating element for electrically insulating the heating element from the casing and filling all air voids between the casing and heating element to effect direct heat transfer to the casing from the heating element, leads coupling the heating elements to a power source, and a control for independently controlling the temperature of the heating elements and thus the temperature of respective zones of the casing.

Abstract: A method and apparatus for cold runner transfer molding. Insulating and/or cooling means are provided so that the mold runnerblock is kept sufficiently cool to prevent curing of the plastic molding compound therein. By the addition of a plunger near the gate of the mold, a quasi-continuous molding operation may be effected. Local preheating of the molding material at the gate locale may be used to liquefy a feedstock which has travelled through the cold-runners in powdered form.

Abstract: A method of controlling the heating of hot runner molds for injection molding of thermoplastic objects is disclosed, whereby the mold cavities (11, 12) receive the material to be molded via channels or runners divided into five heating zones (I through V), the temperature of each zone being controlled by means of an electric heating element (EC) associated with a thermocouple. In the event of failure of one zone's thermocouple, heat control is continued in said zone according to the power applied to the heating element of an adjacent zone.

Abstract: This invention relates to a valve gated injection molding system in which melt flows through an elongated manifold to a number of spaced nozzles to fill a single non-linear cavity. Each nozzle is mounted against a manifold offset block which is bolted to the side of the manifold. Pressurized melt from the manifold flows through a melt duct in each manifold block and through the central bore of the respective nozzle to a gate into the cavity. Actuating mechanism is mounted to reciprocate a valve pin extending through each manifold block and nozzle. Each manifold offset block can be mounted with a different orientation on the side of the manifold to properly space the gates along the non-linear cavity to ensure it completely fills as quickly as possible. Slight lateral movement of each manifold block relative to the manifold is permitted to avoid melt leakage due to misalignment of the nozzles as a result of thermal expansion of the manifold.

Abstract: A mini-extruder apparatus for extruding small quantities of material. The apparatus is designed to overcome the problems of excessive heat transfer from the heated portion of the barrel to the feed portion of the extruder barrel and the premature failure of the long thin extruder screws employed in extruders. The mini-extruder includes an extruder barrel having a substantially circumferential, radially extending cavity formed in an isolator portion of the extruder barrel to thermally isolate the feed portion from the heated portion. The mini-extruder also includes a drive system constructed to drive the extruder screw at both ends. The mini-extruder can also be designed as a co-rotating or counter-rotating twin screw extruder where each end of each extruder screw is driven.

Abstract: The process and apparatus includes a die assembly having a die cavity defined therein and an inlet port in the die assembly communicating with the die cavity. An injection nozzle is provided for delivering molten synthetic resin to the die cavity through the inlet port having an opening aligned with the inlet port and a thermally insulating sleeve positioned around the injection nozzle having an elastically yieldable component and a rigid component.

Abstract: Apparatus for making injection molded polymeric articles, comprising a vibratory pneumatic cooling assembly adapted to dissipate thermal energy from the polymeric articles after they are ejected from the mold cavities through use of an oscillating perforated vibratory grid adapted to maintain the articles in relative motion while at least partially supporting them on a substantially uniform cushion of air. A method for employing the apparatus of the invention to substantially reduce the cycle time required for injection molding polymeric articles is also provided.

Abstract: A hot-runner tool with at least one hot-runner section for supplying molten plastic to an injection mold, preferably a multiple injection mold with a pin-point gate for each casting. The hot-runner section has an outer housing with a flow channel, at least one inlet, and at least one outlet and a heat conductor that can be connected to an electric voltage and that the molten plastic flows around. The flow channel in the hot-runner section is demarcated externally by at least one metal tube that is separated from the heat conductor and a layer of heat insulation is positioned between the metal tube and the inner surface of the outer housing. The metal tube can store and conduct a lot of heat and helps to heat up the plastic rapidly. Since the tube supplies additional heat to those points along the hot-runner section where the plastic needs more heat than at other points, the tube homogenizes the molten plastic along the total length of the hot-runner section.