Abstract: Apparatus for joining cohesive coated plastic sheets in a closed peripheral pattern with bulging of at least one sheet within the closed peripheral pattern to provide a sealed compartment containing only a gas such as air, or foam, under superatmospheric pressure. A method for forming a sealed bulging compartment containing substantially only a gas at superatmospheric pressure comprises joining two cohesive material coated sheets by engagement of said portions of said cohesive material coating at a closed periphery while causing at least one of the sheets to be bulged by gas at superatmospheric pressure. A bulging sealed cushion formed of two sheets each coated on one side with cohesive, air impervious material, at least one of the sheets being bulged outward, and containing substantially only a gas at superatmospheric pressure.

Abstract: An injection-molding method using an injection molding machine having a mold apparatus comprising(A) a fixed mold member,(B) a movable mold member movable in the mold opening and closing directions,(C) an intermediate mold member which is provided between the fixed mold member and the movable mold member and is slidable in the mold opening and closing directions between the fixed mold member and the movable mold member, and(D) at least one intermediate mold member sliding means for sliding the intermediate mold member in the mold opening and closing directions,the method including the steps ofinjecting a molten resin into a cavity formed of cavity wall surfaces of the fixed mold member, the intermediate mold member and the movable mold member, andincreasing the distance of the cavity by moving the movable mold member in the mold opening direction with keeping the intermediate mold member in intimate contact with the fixed mold member or the movable mold member by the intermediate mold member sliding means, an

Abstract: A process for the injection molding of objects having an outer layer of enamel and an inter layer of a plastic material is disclosed. According to the process, a liquid enamel is used. This enamel is injected by an enamel-injection apparatus through an enamel-injection die. A plastic melt passes through an injection unit into the cavity. According to the invention, the liquid enamel is injected into the flow path of the melt in the region before the cavity, before the melt is injected, so that the melt is encased by enamel before it is distributed in the cavity. Variations are also disclosed. For example, the form can be filled with enamel and the excess enamel drained. Then, the melted plastic material is introduced into the injection molding form. Also, the form can filled and then the capacity of the form increased to accommodate the melted plastic material. In any case, it is possible to use liquid enamels to enamel injection molded parts in the tool or form.

Abstract: It is proposed that a pressure control device and/or pressure regulating device (8) be used for a fluid medium, in particular air or gas, preferably nitrogen, which is to be supplied to an injection mold in addition to the molten plastic, this pressure control device and/or pressure regulating device (8) being provided as a stationary, but preferably as a mobile unit between a pressure generator/pressure accumulator (7) and an injection system associated with the injection mold (3), e.g., in a nozzle head or add-on building block.

Abstract: A process for the production of a molded article having a hollow structure, using an injection molding machine equipped with a mold apparatus having a mold provided with a cavity, said process comprising the steps of(a) positioning a plug in its forward end position in the cavity with a plug-moving means before a molten resin is injected,(b) moving the plug toward its backward end position nearly in parallel with a flow-axis direction of the molten resin, with the plug-moving means or under a pressure of the injected molten resin, after the injection of the molten resin is initiated,(c) introducing a pressurized fluid into the molten resin in the cavity through a pressurized fluid introducing portion while the plug is moving, and(d) moving the plug up to its backward end position nearly in parallel with the flow-axis direction of the molten resin with the plug-moving means or under the pressure of the molten resin and/or the pressurized fluid introduced into the molten resin, and then, cooling and solidifying

Abstract: A control system for a gas assisted injection molding apparatus which provides precise and reproducible indication of when the injection of plastic is to terminate and when the pressured gas is to be introduced on basis of sensing of the location of the flow front of the injected plastic in the mold cavity. The flow front sensor control system according to the present invention includes: one or more sensors located at one or more predetermined locations of the cavity of a mold of a gas assisted injection molding apparatus, a controller which processes sensed data from the one or more sensors and thereupon sends a signal to the gas assisted plastic injection molding apparatus to discontinue plastic injection and introduce pressured gas. The preferred type of sensor is a temperature sensor; however, other types of sensors, such as a pressure sensor, may be used.

Abstract: Apparatus for pulsating gas-assisted injection molding hollow tubular plastic parts includes the injection of a molten plastic into a mold cavity in an amount less than the cavity volume and in separate molten plastic flows that flow along the cavity and ultimately unite in a solidifying fusion welding state at an interface. A pressurized gas is injected into the molten plastic to form a central void in the molten plastic extending to opposite sides of the interface leaving a voidless solidifying fusion weld section encompassing the interface. The gas pressure acting on the opposite sides of the interface is trapped and then alternately increased and decreased by a separate gas injection that creates gas pulsations that effect shifting of the molten weld section in opposite directions to force intermingling of the plastic molecules therein and across the interface to enhance the strength of the fusion weld section on solidification and eliminate appearance knit lines.

Abstract: An injection molding apparatus for a resin structure uses gas injection. The apparatus includes a resin supply that feeds more than one resin to a mold, a gas exhaust that discharges gas supplied to the resin in order to closely contact the resin to the mold, and a supply selector that selectively opens and closes the resin supply using the pressure of the discharged gas to supply a different kind of resin onto the inner surface of a previously supplied resin.

Abstract: An injection molded product including a plurality of internal cavities is produced by, after having injected a molten resin material into the molding cavity, injecting an inert gas with a gas pressure gradually increasing into the resin material through gas injection nozzles, which are in contact with the resin material to form the respective internal cavities inside the molten resin material. After removing the gas injection nozzles from the resin material for discharging of the inert gas directly from the resin material, any one of the gas injection nozzles, whose temperature during injection of the inert gas was lower than a predetermined temperature level, is judged to be clogged and the gas injection nozzle is cleaned by being blown out with high pressure gas.

Abstract: A cabinet forming a casing for electronic equipment molded integrally by blow molding, includes a first panel formed to a substantially uniform thickness, a second panel formed to a thickness substantially equal with that of the first panel, and a corner portion formed to a thickness substantially equal with that of the first panel and the second panel and having a cylindrical hollow portion.

Abstract: A gas-feeding nozzle is to be used with a mold attached to an injection molding machine and for introducing a pressurized gas into molten resin injected in a cavity of the mold to produce an injection molded article having a hollow structure. A top forward portion of the gas-feeding nozzle is formed of a gas ejection portion having an inner side wall, along a direction of flow of the pressurized gas, having at least one concavo-convex portion.

Abstract: A method of manufacturing an integral one-piece needle, the method comprising feeding a polymeric resin into a mould cavity and injecting a fluid under pressure into at least a portion of the cavity to eject therefrom the central region of the polymeric resin. This creates an annulus of polymeric resin having an orifice therethrough, the annulus of polymeric resin forming the cannula of the needle, the mounting hub being provided by the remaining portion of the cavity.

Abstract: A molding apparatus for producing a synthetic resin molded product including a forming mold with a molding cavity, a gate communicating with the cavity, and an overflow chamber communicating with the cavity through a flow-out passage, a gas blow-in mechanism for blowing gas into molten synthetic resin which has been injected into the cavity through the gate so as to form a void in the molten synthetic resin in the cavity to mold a hollow product and a flow-out passage opening and closing mechanism for closing the flow-out passage until the molten resin fills the molding cavity and opening the flow-out passage when the gas blow-in mechanism is in operation.

Abstract: A preform (1), a method for blow molding a bottle, and a bottle (13) formed from the preform and by the method are disclosed for use with beverages and the like wherein the bottles usually contain such beverages under pressure. The preform is shaped so that the resultant bottle is provided with a product-containing portion having a preferred hemispherical end portion and an integral bottom portion including a void therein for defining a hollow base portion (4, 12) which, in one form, contains fluid under pressure for balancing pressures related to the pressurized product. The hollow base portion provides for efficient use of material, and a minimal number of manufacturing steps, for providing a stable base for the hemispherical end portion (11) of the product containing portion of the bottle.

Abstract: A method and system for injection molding plastic articles which utilize a spill cavity whose volume varies. In one embodiment, the volume varies during introduction of pressurized gas into a mold cavity flow coupled to the spill cavity. In another embodiment, the volume of the spill cavity varies during a plastic injection which fills the mold cavity. A piston reciprocally mounted within a cylinder defines the variable volume of the spill cavity. In one embodiment, a pneumatic control circuit controls the pressure on a lower surface of the piston to thereby control the position of the piston within the cylinder and therefore the volume of the spill cavity. In another embodiment, an air spring is utilized to control pressure on the piston which counters the pressure of the plastic on the piston. In one embodiment, a stop pin connected to the piston prevents the piston from leaving the cylinder when the mold is opened and solidified plastic in the spill cavity is to be ejected therefrom.

Abstract: The invention relates to a method for fabricating hollow plastic objects of thermoplastic material, comprising the following steps: 1) injecting melt into the tool cavity (1,2); b) Simultaneously and/or subsequently introducing a pressurized fluid into the melt, so that the melt which has been introduced into the molding tool (1, 2) is distributed in the cavity and is pressed against the walls of the molding tool (1, 2), the pressurized fluid being conducted from a pressurized container (5) into the melt, and the pressurized container (5) being supplied with fluid by a compressor (7) which contains a drive element (6); c) allowing the molded part (8) to cool; and d) relieving the cavity of the pressure of the pressurized fluid. According to the invention, the drive element (6) of the compressor (7) is maintained at a temporally constant power level (P) at least over the production of a large number of plastic objects.

Abstract: An injection-molding apparatus for making a hollow-wall container having sides and a base has front and rear mold parts together forming side surfaces of a mold cavity centered on an axis and a floor mold part defining a base surface of the mold cavity. An inner core sleeve and an outer core sleeve are axially displaceable relative to each other and to the mold parts and have front ends. The sleeves together form a passage extending to the front ends and the front ends form a compartment. A sleeve actuator can displace the sleeves axially between a front position with the front ends of the sleeves projecting relatively far into the cavity and a rear position with the front ends of the sleeves generally retracted from the cavity. A piston/cylinder unit formed between the sleeves connected to the passage is pressurizable to shift the sleeves relative to each other and thereby open up the compartment into the cavity. A floor actuator can axially shift the floor between front and rear positions.

Abstract: Disclosed are expandable bladders for use in curing presses for rubber compositions such as pneumatic tires. The bladders are a crosslinked elastomer comprising an isobutylene rubbery polymer. The bladder composition includes corn oil which improves the release characteristics of the cured bladder from a tire innerliner cured in contact with said bladder. The improved release characteristics have been observed to allow rubber compositions such as tires to be molded with fewer defects caused during release of the bladder from the tires or caused by abraded or deformed bladders. The use of corn oil also has been observed to increase the useful life time of the bladder allowing more tires to be cured without changing bladders. A preferred isobutylene rubbery polymer is a brominated copolymer of isobutylene and p-methylstyrene. The bladder compositions have also been observed to have an enhanced flexibility due to the corn oil.

Abstract: A molded protective strip for automobiles is prepared by the gas injection molding of a resin composition which comprises (A) 55 to 75% by weight of polypropylene, (B) 18 to 30% by weight of ethylene-propylene copolymer rubber, and (C) 10 to 20% by weight of talc, has a ratio (MI).sub.PP /(MI).sub.EPR of 10 or less, and a polydispersity index of 20 to 100. (MI).sub.PP and (MI).sub.EPR represents melt indices of the polypropylene of component (A) and the ethylene-propylene copolymer rubber of component (B), respectively. The polydispersity index is calculated from a frequency-storage modulus curve obtained with a composition consisting of components (A), (B), and (C) alone at the temperature of 230.degree. C. The molded protective strip can be prepared without using a vinyl chloride resin, shows almost no heat shrinkage, has a small coefficient of linear expansion, is excellent in dimensional stability, and exhibits excellent appearance.

Abstract: A process for producing a skin material-laminated hollow molded article of thermoplastic resin, using a mold having, in any one or both of its fixed and movable parts, at least one fluid-ejecting pin which can be slid in a clamping direction and which has a fluid-ejecting hole at its pointed end. The process consists of fixing two sheets of a skin material having a tensile modulus at ambient temperature of 50-1,000 kg/cm.sup.2 and a tensile modulus at 80.degree. C. of 5 to 100 kg/cm.sup.2 on the parting surfaces of both the mold parts which are in the open state. A molten thermoplastic resin is fed between the skin materials in an amount of 5 to 50% by volume of the cavity volume. The fluid-ejecting pin is thrusted so that its pointed end penetrates one of the skin material sheets and comes between the skin material sheets. The mold parts are closed to wrap the molten thermoplastic resin in between the skin material sheets.

Abstract: Tooling and method for gas assist injection molding of plastics material into a hollowed part in which a mold chamber formed between stationary and movable mold tools is initially charged with an inert gas to provide a resistance force against the flow front of a short shot of plastics melt subsequently injected into the cavity and supplied with a pressurized assist gas so that the velocity of the flow front of the short shot expanded by the assist gas in the mold chamber is modulated by the controlled release of the retarding chamber charge gas to prevent blow out of the short shot while eliminating flow hesitation lines to improve molded part appearance and uniformity of part wall thickness.

Abstract: The apparatus includes an air compressor (13), which is cooled by direct oil injection, and an air cooler (14) connected downstream of it which serves as a condensate separator. Connected to it is a heat exchanger (18) which is heated by the waste heat from the oil discharged from the air compressor (13). The temperature of the air is raised thereby to a level at which the separators (4) downstream thereof develop their optimum efficiency. The nitrogen flowing out of the separators (4), the purity of which is predetermined by a downstream throttle (3), flows into an inflatable reservoir (5) which is connected to the suction side of a high pressure compressor. The latter discharges into a high pressure storage container which for its part supplies an injection moulding machine. The nitrogen is conveyed in a closed circuit between the injection moulding machine and the inflatable reservoir.

Abstract: A system for injection molding a hollow plastic article utilizing a secondary resin flow path which communicates one portion of an article-defining cavity with a second portion of the article-defining cavity. The second portion of the article-defining cavity is typically the hardest-to-fill area of the article-defining cavity. The secondary resin flow path is outside of the article-defining cavity and the normal flow of plastic resin.

Abstract: A gas-feeding device as follows:(A) a gas-feeding nozzle and(B) gas-feeding nozzle shifting device for putting a top portion of the gas-feeding nozzle in forward and backward movement in a guide portion which is provided in a mold and communicates with a cavity and an outside of the mold,the gas-feeding device being used for feeding a pressurized gas through the gas-feeding nozzle into a molten resin injected into the cavity of the mold attached to an injection molding machine for producing a molded article having a hollow portion,wherein:a clearance is provided between the top portion of the gas-feeding nozzle and the guide portion, andat least part of the top portion of the gas-feeding nozzle is out of contact with the guide portion when the molten resin is injected into the cavity.

Abstract: When injection-molding a molten thermoplastic resin into a molding having different thicknesses, a void inducing member is set in a cavity corresponding to heavy sections. Then gas pressure is applied passing through a gas passageway to a tip end of the void inducing member, thus forming a void nucleus in the resin adjacent to the tip end of the void inducing member. The void nucleus develops to a void by shrinking force of the resin as the molten resin cools.

Abstract: A method for manufacturing synthetic resin containers which are excellent in strength, toughness and heat insulation and have inner surfaces smooth and agreeable to the touch. The method including the steps of: (a) forming an inner surface layer component from a synthetic resin sheet by thermoforming; (b) fitting the inner surface layer component onto a male die; (c) pouring a synthetic resin in a melt condition into the inside of a female die; (d) fitting the male die onto the female die and bringing it close to the female die to compress the synthetic resin; (e) injecting compressed air into the synthetic resin through at least one air nozzle formed in the female die while enlarging a gap between the male and female dies so as to correspond to a predetermined thickness of a prospective molded product; (f) causing the compressed air to press the synthetic resin against entire inner surface of the cavity; and (g) cooling the synthetic resin to solidify the same and releasing the product from the dies.

Abstract: A method and system for the injection molding of plastic articles in an injection molding system including a chamber in a mold of the system which stores a charge of pressurized gas immediately prior to use. The mold has an injection aperture and a mold cavity for receiving molten resin. A resin flow path fluidly communicates the injection aperture and the mold cavity within the mold. An orifice in the mold opens the chamber to the mold. A gas receiver initially stores the charge of pressurized gas and a fluid circuit selectively introduces the charge of pressurized fluid into the chamber. A valve mechanism in the chamber selectively fluidly communicates the chamber to the flow path under control of a controller. When communicated to the flow path, the charge of gas distributes the molten plastic within the mold cavity in one embodiment of the invention.

Abstract: A gas assisted injection molding machine includes an injector valve assembly secured to the clamping plate and having an elongate supply duct extending through the core and into the mold cavity. The duct supports a valve member for sliding movement and is itself supported in the core by an ejector sleeve. The ejector sleeve moves with the ejection mechanism to force molded articles off the end of the supply duct.

Abstract: A process for injection molding of thermoplastic materials which includes a nozzle body having a bore to provide a flow path for molten thermoplastic. One end of the nozzle body is adapted for connection with a sprue of an associated mold body, and the other is adapted for connection with an end of an associated injection molding machine. The nozzle body has a shut-off valve fluid pin housing adapted for reciprocating movement in the nozzle bore to control the flow of plastic through the nozzle body. The shut-off valve fluid pin housing also includes a body having a fluid pin with a tip portion and a fluid passage formed in the body and open at the tip portion and the other end of the fluid passage communicating with a source of two pressurized fluids, one in vapor and liquid phase and another in gas.

Abstract: A shift knob for use with automatic automotive transmissions has a one-piece body construction molded from a hard resin. The knob body is formed by gas injection molding, has a substantially uniform wall thickness and is covered with a soft resin. The knob body has a relatively thick bulbous grip portion at one end and gradually tapers to a slimmer lower end portion.

Abstract: A vent valve for a gas assisted injection molding machine has a valve member to control flow from the mold cavity. A shear co-operates with an anvil in the passageway between the mold and valve member to sever material in the passageway as the molded article is ejected.

Abstract: Method and apparatus for pulsating gas-assisted injection molding hollow tubular plastic parts includes the injection of a molten plastic into a mold cavity in an amount less than the cavity volume and in separate molten plastic flows that flow along the cavity and ultimately unite in a solidifying fusion welding state at an interface. A pressurized gas is injected into the molten plastic to form a central void in the molten plastic extending to opposite sides of the interface leaving a voidless solidifying fusion weld section encompassing the interface. The gas pressure acting on the opposite sides of the interface is trapped and then alternately increased and decreased by a separate gas injection that creates gas pulsations that effect shifting of the molten weld section in opposite directions to force intermingling of the plastic molecules therein and across the interface to enhance the strength of the fusion weld section on solidification and eliminate appearance knit lines.

Abstract: A method of evacuating uncured resin from internal passages of semi-hollow stereolithographically produced objects includes, subjecting the object to air flow for between about 0.5 hours and about 2 hours, at a temperature greater than about 75.degree. F.; externally cleaning the object with alcohol; submerging the object in a bath of alcohol, wherein the bath is internally agitated; removing the object from the bath and repeating the above steps to displace any residual resin, wherein total object exposure time to alcohol does not exceed three hours.

Abstract: The present invention provides polyhydric phenols which are starting materials for glycidyl ether compounds which can provide cured products having low moisture absorption, high heat resistance and improved crack resistance and can be used for encapsulating semiconductor devices. The polyhydric phenols are represented by the following formula: ##STR1## wherein R.sup.1 independently represents a halogen atom, an alkyl or cycloalkyl group of 1-9 carbon atoms, an alkoxy group of 4 or less carbon atoms or an aryl group and R.sup.1 may be identical or different when l is 2 or more, R.sup.2 independently represents a halogen atom, an alkoxy group of 4 or less carbon atoms or an alkyl group of 6 or less carbon atoms and R.sup.2 may be identical or different when m is 2 or more, R.sup.

Abstract: A device for injection molding articles of plastics material having hollow spaces. The device includes a molding tool with a mold cavity. Plastics material melt is fed to the mold cavity through a nozzle. Another pressurized medium is supplied to the mold cavity through a hollow needle at a location different from the location of the nozzle. A needle core is mounted in the hollow needle. The needle core is axially displaceable within certain limits. The opening of the hollow needle to the mold cavity can be opened and closed or its cross-sectional area can be varied by moving the needle core.

Abstract: An apparatus for injecting a viscous fluid and a non-viscous fluid into a mold cavity of a mold body includes a nozzle body having a discharge end a flow passage for the viscous fluid extending to the discharge end. A valve element is mounted for reciprocation in the nozzle body flow passage to control the flow of the viscous fluid through the nozzle body discharge end. The valve element includes a barrel having a first end and a second end and a first bore extending longitudinally in the barrel. A tip is detachably secured to the barrel first end for selectively engaging a portion of the nozzle body discharge end to prevent a flow of the viscous fluid therepast. The tip has a first end, a second end and a second bore extending longitudinally through the tip from the first end to the second end. A pin is located in the second bore. The pin has a first end located adjacent the tip first end, such that the pin and the tip define between them an annular opening at the tip first end.

Abstract: A method for producing polymeric tubing which is resistant to permeation by organic material contained therein which has at least one region defined by a plurality of outwardly extending annular ridges. In this method, tubular polymeric material having a first outer diameter and composed of at least three overlying polymeric layers is introduced into a mold device upon exit of the tubular polymeric material from a suitable extrusion device, the surface of the mold device having at least one region defined by an annular depression in an essentially cylindrical surface. Once the tubular material is introduced, it is expanded to a second outer diameter such that the tubular material deformably contacts the mold surface. The corrugated tubular material then exits from the die device after completion of the expansion step.

Abstract: An injection mold apparatus has a core and cavity halves. One or more gas poppet valves are affixed in the injection mold either in the movable and/or in the stationary halves of the mold. The poppet valves (or poppets) are located to open into a mold portion formed in the cavity between the movable portion of the injection mold and the fixed mold portion when the mold portions are closed. At least one gas line is connected to the poppets and to a gas pressure source and is adapted to open the poppets to the passage of nitrogen or other gas into the mold following the injection of molten plastic into the closed mold halves. Porous metal covers may be used to cover the opening in the mold either the movable and/or stationary halves of the injection mold in lieu of the gas poppet valves, and the gas pressure through the porous metal cover can be used to carry out the molding operation.

Abstract: A method of injection molding for use with an injection molding machine includes: (a) generating pressurized gas and pressurized moisture within molten plastic as plastic pellets are plasticized in the injection molding machine, the pressurized gas and the pressurized moisture having a total pressure defining an internal counterpressure within the molten plastic; (b) pressuring air within a cavity of a mold in the injection molding machine to an air pressure level which is substantially equal to the internal counterpressure in order to counterbalance the internal counterpressure as the molten plastic is injected into the cavity, thus providing a substantially pressure balanced molding environment for the plastic; and (c) maintaining the air pressure level in the cavity substantially constant as the molten plastic is injected into the cavity.

Abstract: A mold apparatus and method is used to form a solid injection molded plastic part having no internal voids, a Class A finish, a sink-free exterior appearance surface, and unevenly distributed structural detail extending from the opposite surface, the detail including free-standing reinforcement ribs, attachment bosses, and the like. A charge of hot melted thermoplastic and pressurized gas are sequentially injected into a mold cavity defining the shape of the desired part, the plastic not filling the cavity and being simultaneously received in shaped recesses and grooves which form the structural detail. The pressurized gas forces the hot plastic from one mold half against the other mold half, and into the recesses and grooves, and is maintained during cooling. A gas seal is formed by the plastic to prevent gas in the mold cavity from reaching the finished exterior surface of the part during shrinkage of the plastic.

Abstract: A device for producing moldings of plastic material having a cavity therein filled with a fluid comprises a mold cavity, an injector for injecting flowable plastic into the mold cavity, an injector for injecting a pressurized fluid into an interior portion of the plastic, and a side cavity connected to the mold to receive flowable plastic melt expelled by the injected pressurized fluid. The side cavity may be randomly lockable and may comprise a closing stuffer which rests flush with respect to the mold cavity interior walls.

Abstract: A drive apparatus for driving a movable member of a plastic molding die apparatus is provided which drives and controls a movable shaft for holding a gas injection nozzle by using a plurality of cylinders so that the gas injection nozzle of the die apparatus for use in a gas injection molding method can easily be changed. Resin is supplied from a position through a second die into a cavity formed between a first die and the second die, the drive apparatus disposed adjacent to the first die is used to drive the movable shaft for holding the nozzle of a gas supply means to supply gas into the resin in the cavity so that a hollow product is molded. The nozzle of the gas supply means is disposed at the leading portion of the hollow movable shaft.

Abstract: A method and system for injection molding a hollow plastic article utilizing a secondary resin flow path which communicates one portion of an article-defining cavity with a second portion of the article-defining cavity. The second portion of the article-defining cavity is typically the hardest-to-fill area of the article-defining cavity. The secondary resin flow path is outside of the article-defining cavity and the normal flow of plastic resin.

Abstract: A gas control unit for a gas-assisted injection molding system, wherein a quantity of gas is introduced into a mold cavity in combination with a quantity of plastic material during the molding process. The gas control unit operates on the basis of regulating the mass of gas within the system, as opposed to the final hold pressure. Because the mass of the gas is constant within the gas control unit throughout an injection cycle, a preferred initial-to-final (hold) pressure ratio can be determined through mathematical computations for a particular molding system. As a result, once the required mass of gas has been isolated from a suitable source, releasing the gas to the mold cavity results in a predictable pressure. This capability permits the gas control unit to determine whether the gas has fully expanded and, therefore, whether the gas has properly filled the mold cavity so as to produce a properly molded article.

Abstract: The invention relates to a hollow injection-molding method of forming a hollow portion in molten resin in a mold cavity by introducing a pressurized fluid, and also to a pressurized fluid introducing and discharging apparatus therefor, and has an object of eliminating the backflow of the molten resin into a pressurized fluid passage. A gap between a cylindrical sleeve and a shaft core inserted into the sleeve is used as the pressurized fluid passage. The front end of the shaft core is projected into a mold beyond the sleeve front end to serve as a guide face. By sliding the shaft core, the state of an opening portion of the pressurized fluid passage in the side of the mold is changed between a narrowed state where the pressurized fluid can pass through the opening portion but the molten resin cannot enter the opening portion and a widened state allowing the pressurized fluid to rapidly discharge. The guide face allows the pressurized fluid to be reliably introduced into the mold cavity.

Abstract: Improvements in articles, made by gas assisted injection molding of polyethylene and other materials, such as large arch shaped subsurface leaching conduits, and the processes by which they are made, are disclosed. The improvements involve control of which portions are hollow and which are solid, and include a stepped rib, where the thinner upper rib portion is solid and the wider base is hollow; articles having corrugated surfaces strengthened by ribs on both sides, where the hollows of the opposing side ribs are connected through holes in the undulating walls; articles having ribs which are narrowed where they are solid, compared to their width where they are hollow; and, articles having thinned wall regions surrounding sprues, to avoid undesired hollowing during injection molding.

Abstract: An apparatus and method are provided for producing a hollow molded product having a thick part free from a thin part or defect. According to the method, a mold is designed to have a cavity for a hollow molded product having a bent portion such as an assist grip. This mold is provided with dams mounted in a gas passage around an in-course in the bent forming portion. When injecting fluid into the already injected resin in the cavity, the dams are so designed to function in guiding the resin to flow between the dam and an out-course of the cavity. By this method, sufficient amount of the resin remains around the in-course so as to form a thick part of the hollow molded product.

Abstract: A structurally reinforced panel for a vehicle body includes an injection molded resin panel having an integrally molded hollow reinforcement truss extending across the panel.

Abstract: A process for producing expanded plastic with a skin and a molding apparatus therefor, the process including blowing a parison being held in a closed blow mold to obtain a hollow article, filling the hollow article with thermoplastic preexpanded resin beads before the hollow article is cooled to solidify, heating and fusing said beads, and cooling the expanded plastic. A hollow article and an expanded body are completely fused together, and improved productivity is obtained.

Abstract: A gas injector having a retractable nozzle with linear gas feed passage therethrough for a gas assist plastics injection molding machine. The injector interfaces with the injection molding tool and has a nozzle with a tip that, in a forward position, protrudes through a port therein leading into the tool cavity or a runner system leading into the cavity for gas injection during molding. The nozzle tip is connected by a nozzle body to a base that is operatively mounted in an actuator housing. The base is connected to an in-line gas routing extension of the nozzle that projects through the outer cover of the housing. The extension is coaxial with an internal spring that seats on the base and holds the nozzle tip in a gas injection position resisting the force of plastics injection pressure.