Abstract: A method and an apparatus for producing plastic objects with hollow spaces is disclosed. The method comprises the following steps: establishing a fluid connection (9) between the main cavity (2) of a mold (1) and an overflow cavity (8) and injecting a sufficient amount of plastic melt into the cavity (2) of the mold (1) along a melt flow path, which extends from a plasticizing unit (4, 5) through a plastic injection nozzle (3) into the mold (1), such that plastic melt passes from the main cavity (2) into the overflow cavity (8). The fluidic connection (9) between the main cavity (2) and the overflow cavity (8) is then broken-off prior to the introduction of a pressurized fluid, especially a pressurized gas, into the melt in the cavity (2) by means of at least one fluid injection nozzle (7), so that the melt situated in the cavity (2) is distributed in the cavity (2) while forming a hollow space, and is pressed against the cavity walls of the mold (1).

Abstract: A hydraulic operating system for plastic processing machines, especially for injection molding machines, comprises a hydraulic pump (1), which is driven by an electric motor (2), at least one hydraulic drive (3, 4, 5), a hydraulic line network (6), which connects the hydraulic pump (1) and the hydraulic drives (3, 4, 5), and a machine control (7), in which the hydraulic pump (1) is designed a continuous or constant transport pump and the electric motor (2) is operated at a variable rpm, being appropriately influenced by the machine control (7).

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: A hydraulic operational system for an injection molding machine, including a hydraulic line network, a plurality of hydraulic drives for driving different components of the injection molding machine, a plurality of directional control valves, for connecting the hydraulic drives with the network, a constant delivery pump for supplying the hydraulic line network with hydraulic fluid, and a steplessly controlled electric motor or a multi-stage electric motor for driving the constant delivery pump, and a maximum driving speed of which is controlled so that it corresponds to the hydraulic pump operation at which the hydraulic pump provides at least one of a delivery volume and a hydraulic fluid pressure corresponding to the at east one of a maximum amount of the hydraulic fluid and a maximum pressure of the hydraulic fluid required for operating all of the plurality of hydraulic drives.

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 closing unit for injection mold machines is disclosed which generally includes two end plates, guide crosspieces connecting the end plates at a distance from one another, an intermediate plate which is parallel to the end plates and displaceable longitudinally relative to the guide crosspieces and moving cylinders which abut an end plate and act at the intermediate plate via their piston rods. The moving cylinders also displace the intermediate plate along the guide crosspiece in the closing and opening direction to vary its distance from the other end plate. The intermediate plate and the other end plate form a gripping plate for the two mold halves of a form tool which is brought into its closing position by the two gripping plates. Increased closing force may be applied to the form tool at a central die via a pressure cushion insertable between one end plate and the intermediate plate.

Abstract: A displacement and/or actuating force drive device for an injection molding machine, for example, for actuation of the push-type screw of a plasticizing extruder or the closing unit of an injection mold, comprises generally a hydraulic stroke drive, in tandem in rows or in series with a mechanical stroke spindle system driven by a brushless three-phase servomotor type electromotor. The motor is associated with a positioning regulation device dependent upon the closing and opening position of the injection mold. The hydraulic stroke drive can be actuated from a pressure regulation circuit by a servo valve. The circuit depends upon the closing force between the two mold halves of the injection mold.

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: An apparatus for injection molding of plastics material in accordance with a gas or liquid injection method. The apparatus includes a nozzle which can be applied to the injection molding die or the injection mold. This nozzle enables selectively the sole injection of plastics material melt, the simultaneous injection of plastics material melt and medium as well as the sole injection of medium into the mold cavity of the injection molding die or injection mold. The melt is supplied to the nozzle mouth by the extruder screw cylinder of the extruder around a nozzle torpedo, while the medium is introduced into the nozzle so as to be spaced from the nozzle mouth.

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: An arrangement for securing a die to a die holder for use as a molding die in an injection molding machine permits the die to be oriented on the die holder in a number of different angularly rotated positions. Clamping bolts secured to the die extend perpendicularly of a contacting plane between the die and die holder and project into corresponding holes in the die holder. Slides are provided in passageways in the die holder with the passageways extending parallel to the contacting plane. The slides are displaceable in the passageways into securing and clamping engagement with the clamping bolts. The slides are wedge-shaped and inter-engage corresponding wedge-shaped recesses in the outer surface of the clamping bolts. The slides can be displaced by actuating members. Hydraulic piston cylinder units can be used as the actuating members for holding the slides in the clamped position during operation.

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 hydraulic closing unit, particularly for injection molding machines which process plastics material. The closing unit includes a mold clamping plate which is slidably guided on guide columns between a stationary support plate and a stationary mold clamping plate. An annular main piston acts on the slidable mold clamping plate with a high mold closing force in mold closing direction. The main piston is axially slidably guided in the stationary support plate and load can be applied to both sides of the main piston. At least two coupling planes are provided between the main piston and the central pressure column. The coupling planes are mounted spaced apart and one behind the other in sliding direction of the slidable mold clamping plate. The main piston and the pressure column are slidable relative to each other over the distance range between the coupling planes.

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: A method of injection molding thermoplastic material from an injection molding machine including a slidable screw into a mold whose optimum pattern of the injection rate has been determined on and is known for another injection molding machine. The method includes transferring the defined optimum characteristic values for a first injection molding machine onto a second injection molding machine. The known optimum injection flow rate pattern (V.sub.A) of a previously used first injection molding machine is introduced manually and/or by means of data carriers into a control device of a second injection molding machine to be used. The second injection molding machine is operated with any compatible injection flow rate pattern (V.sub.b), with the resulting injection time (t.sub.Eb) being adjusted to that of the first injection molding machine by means of a multiplicative change of the injection flow rate pattern. Forming an adjustment factor K.sub.V =V.sub.b /V.sub.

Abstract: A quick changing and quick gripping device for the molding tools of injection molding machines. The two mold halves of each molding tool are alignable in insertion guides between two adapter plates located opposite each other. The adapter plates are movable toward each for closing the molding tool and are movable apart from each other for opening the molding tool. The mold halves can be fixed in their aligned position by means of clamping members. During the changing and/or gripping procedure, the two mold halves of the closed molding tool are fixedly locked or coupled to each other. At least one locking bar is movably mounted in a mold half and automatically engages a locking bar engagement member mounted in the other mold half by means of a biasing force, such as, a spring. The locking bar includes an actuating element which projects into the range of an intermediate plate of the respective mold half, the intermediate plate being capable of being operatively connected to the clamping members.

Abstract: A device for manufacturing molded articles of plastics material which have an outer skin of a plastics material free of expanding agents and a porous core of a plastics material containing an expanding agent includes an extruder head with a main duct in communication with a discharge opening. Two feed ducts for the two plastics materials lead angularly offset into the main duct at locations axially spaced from the discharge opening and from each other. A closing needle is axially movably placed in the main duct. The two feed ducts can be separated from the main duct by means of the closing needle. The closing needle defines a connecting duct extending essentially in axial direction. The connecting duct ends at the end face of the closing needle and at the circumference of the closing needle radially toward the more remote feed duct.