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: 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: The invention relates to a method for fabricating hollow plastic objects of thermoplastic material, having the following steps: a) 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: A method and an apparatus are disclosed for producing plastic objects with solid regions and hollow regions. The method has the following steps: a) blocking off a part of the cavity (2) of a molding tool (1), so that little or no plastic melt can reach the blocked-off region (8); b) injecting plastic melt into the unblocked region (9) of the cavity (2) of the molding tool (1); c) releasing the blockage, so that plastic melt can reach the previously blocked-off region (8) of the cavity (2); d) injecting a pressurized gas into the melt by means of at least one fluid injection nozzle (7), so that the melt injected into the molding tool is distributed into the desired regions of the cavity (2) while forming a hollow space and is pressed against the cavity walls of the molding tool (1); e) allowing the molded part (6) to cool; f) relieving the cavity (2) of the pressure of the pressurized fluid; and g) demolding the molded part.

Abstract: A method and an apparatus for producing plastic objects with hollow spaces is disclosed. The method comprises the following steps: injecting a sufficient amount of plastic melt into the cavity (2) of the molding tool (1); simultaneously and/or subsequently injecting a pressurized fluid into the melt by means of a fluid injection nozzle (7); allowing the molded part (6) to cool; relieving the cavity (2) of the pressure of the compressed fluid, and demolding the molded part, while plastic melt is driven out into at least one overflow cavity (8), which is connected to the cavity (2). According to the invention, the volume of the overflow cavity (8) is changed, and in particular enlarged. This volume increase advantageously is controlled or regulated. The advantage achieved thereby is that the injection molding cycle, especially the overflow of melt into the overflow cavity (8), remains controllable by simple means.

Abstract: The proposal is for a device for injection molding plastic items enclosing hollow spaces with which a further pressurised medium like air, gas or a fluid can be introduced through a hollow needle (5) at a point differing from the nozzle into a mould (1), the mould hollow or cavity (4) of which can be filled with molten pastic through a nozzle. There is a needle core (9) which can be moved axially to a limited extent in the hollow needle (5) and it is possible via this needle core (9) to vary the cross-section of or open and close the aperture (16) of the hollow needle (6) opening into the mould hollow or cavity (4). The needle core (9) bears a thickened head or plate (10) in front of the end of the aperture in the hollow needle, the outside diameter of which corresponds at least approximately to the outside diameter of the hollow needle, so that it forms, with the aperture end (6) of the hollow needle (5), a radially directed splitting valve.

Abstract: A method of injection molding of workpieces, formed of at least two different layers, and which includes forming at least one layer from lacquer, with the apparatus for effecting the method including at least two injection molding devices for forming melts of lacquer and non-lacquer materials and an injection unit communicating with the two devices for injecting the two melts into a mold cavity of a mold.

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: 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: 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: A method and an apparatus of injection molding articles of thermoplastic material. The method includes initially forcing molten plastics material into an injection mold in an amount sufficient for forming the article. Subsequently, a flowable medium is forced into the injection mold with a pressure which distributes the plastics material uniformly over the surface of the mold cavity of the injection mold so as to form a hollow body. The hollow body is then cooled while the pressure of the medium is maintained. Finally, the pressure of the medium is released and the molded article is removed from the injection mold. The pressure of the medium in the mold cavity is controlled and/or varied at least temporarily until the plastics material has cooled. The apparatus for carrying out the method includes a pressure reservoir for the medium which is connectible to the injection mold through lines. The lines include control and/or regulating elements.

Abstract: A method of manufacturing multiple-layer molded articles with an outer skin of compact thermoplastic material and a core of foamed thermoplastic material includes initially introducing the material for the skin into a mold cavity in a quantity sufficient for the desired thickness of the skin and subsequently feeding into the mold cavity the material for the core to which the expanding agent has been added. During and/or after being introduced into the mold cavity, the core material containing expanding agent is temporarily subjected by means of an additional gas and/or a pressurized, low-boiling liquid to an active pressure which exceeds the gas pressure of the expanding agent. Subsequently, the additional gas or the low-boiling liquid is removed from the hollow space which is still free of skin material and core material.

Abstract: A method and an apparatus of injection molding articles of thermoplastic material. The method includes initially forcing molten plastics material into an injection mold in an amount sufficient for forming the article. Subsequently, a flowable medium is forced into the injection mold with a pressure which distributes the plastics material uniformly over the surface of the mold cavity of the injection mold so as to form a hollow body. The hollow body is then cooled while the pressure of the medium is maintained. Finaly, the pressure of the medium is released and the molded article is removed from the injection mold. The pressure of the medium in the mold cavity is controlled and/or varied at least temporarily until the plastics material has cooled. The apparatus for carrying out the method includes a pressure reservoir for the medium which is connectible to the injection mold through lines. The lines include control and/or regulating elements.

Abstract: A method for manufacturing multilayer molded articles of at least two plastics material components having substantially different properties with respect to behavior, processing and/or temperature changes. The plastics material components are injected from different extruder unit through a common sprue brushing into a mold cavity of a molding tool. The plastics material components are introduced in a predetermined time sequence initially into different cross-sectional areas of a common sprue cone and are subsequently forced into the sprue cone in a converging manner toward a sprue duct of the sprue bushing.

Abstract: An injection-molding apparatus has a nozzle extending along an axis and formed with an axially forwardly opening outlet, an annular port fixed immediately axially behind or upstream of the outlet, and a central axially forwardly opening port axially fixed behind the annular outlet. Respective plastifiers for feeding respective plastified synthetic resins, normally thermoplastics, are connected to the respective ports. An axially displaceable valve body in the nozzle is displaceable from a fully forward position blocking both of the ports, through a partially back position blocking only the central port, to a fully back position clear of both of the ports. Thus in the fully forward position no resin can enter the nozzle, in the partially back position resin can enter the nozzle only from the annular port, and in the fully back position resins can enter the nozzle through both of the ports.

Abstract: A method for injection molding a product having a non-cellular skin layer and a cellular core portion. The method involves successive or simultaneous injection of a non-foamable resin material and a foamable resin material through a sprue bushing having an injection channel connected to the mold cavity and a pair of fixed feed channels intersecting with the injection channel. The injection mold has a bore with a sprue bushing therein. The sprue bushing having an injection channel therein and intersecting with a pair of fixed feed channels. Injection units deliver the materials to the pair of fixed feed channels.

Abstract: Apparatus for injecting thermoplastic material including means to form a tubular stream of plastic with a central stream containing a foaming agent.

Abstract: Process and apparatus for injection molding plastic to provide a foamed core with an unfoamed outer skin.

Abstract: Method and apparatus for the intermittent manufacture of multi-layer molded bodies of thermoplastic material with a foamed core and an unfoamed shell, wherein a strand of a nonfoaming plastic of ring-shaped cross-section enclosing a strand of plastic containing a foaming agent is injected into a mold.