Abstract: In the production of a reaction mixture which forms plastic material, in particular foamed plastic material, from at least two flowable reaction components, the inlet members or other switch-over members which must be switched over in a precise fashion, are controlled by a sliding valve comprising a slide which is assigned a restoring spring which operates in opposition to a moving electromagnet, and a holding electromagnet. First, the holding electromagnet is fully activated whereupon the moving electromagnet is activated. Following the build-up of force of the moving electromagnet, the holding electromagnet is switched off so that the inlet member or other switch-over member opens abruptly.

Abstract: A process and apparatus are described for the production of a flowable reaction mixture from at least two flowable reactive components which may be difficult to mix, which components react with one another to form a solid or a foam material. The components are injected into a mixing zone where they components are mixed in a continuous flow. The mixture flowing from the throttle zone is divided into two sub-streams which flow around a piston and which recombine opposite the division point.

Abstract: The present invention is directed to an apparatus for introducing gas into one of at least two free-flowing components which are subsequently mixed to provide a foam-forming free-flowing mixture by transferring the component to have gas dispersed therein from a supply container to a gas loading area, loading the component with gas and returning the component to the supply area, wherein the gas used in the gas loading area is obtained from a gas cushion maintained in the supply container and wherein the gas is compressed to a pressure higher than the pressure in the gas loading area before it is dispersed into the free-flowing component.

Abstract: In order to keep the reversing times from circulation of the reaction components to mixing and vice versa as short as possible for the purpose of good mixing in the initial and end phases in the preparation of flowable reaction mixtures by high-pressure mixing, the holding pressure applied to the flow reversing element is maintained by a releasable non-return valve until the full hydraulic reversing pressure has built up on the opposite side, and only then is the non-return valve released.

Abstract: To avoid contaminating the sprue runner which leads from the mixing device to the molding cavity of a molding tool for the production of molded plastic, especially foam plastic, parts, an insertable lining is placed in the sprue runner and can be removed along with the molded part.

Abstract: The present invention is directed to a process and apparatus for introducing gas into one of at least two free-flowing components which are subsequently mixed to provide a foam-forming free-flowing mixture by transferring the component to have gas dispersed therein from a supply container to a gas loading area, loading the component with gas and returning the component to the supply area, wherein the gas used in the gas loading area is obtained from a gas cushion maintained in the supply container and wherein the gas is compressed to a pressure higher than the pressure in the gas loading area before it is dispersed into the free-flowing component.

Abstract: The invention relates to a nozzle for mixing at least two flowable (and in particular foam-forming) reaction components comprising a housing; component supply pipes leading into the housing; a housing bore arranged in the housing having a coaxial outlet channel in its end face; at least one needle casing arranged coaxially in the housing bore; an injection needle guided coaxially in the needle casing; a first chamber arranged between the wall of the housing bore and the needle casing with one of the component supply pipes opening into said first chamber; a second chamber arranged between the needle casing and the injection needle, with another component supply pipe opening into said second chamber; wherein in the closed state, said injection needle forms a tight fit with the internal end face of the needle casing, and the external end face of said needle casing forms a tight fit with the internal end face of the housing bore; and wherein in the open state, said injection needle frees a coaxial nozzle opening

Abstract: A nozzle is used to mix two or more flowable reaction components which nozzle has a force controlled injection needle (7) and a force controlled needle casing (12) guided in a guiding bore (12). One component emerges centrally into an outlet channel (3) while the opening (25,26) of at least one further supply pipe (23,24) lies in the area of a sealing surface (4) which limits one side of the guide bore (2) and which forms a tight fit (18) with an outer sealing surface (17) thereof when the needle casing (12) is in a closed position.

Abstract: The instant invention is directed to a process for filling a cavity with a flowable reaction mixture through an inlet opening located at the bottom of the cavity. The process broadly comprises injecting a relatively small amount of reaction mixture into the cavity to cover the inlet opening with reaction mixture. The injection process is then briefly interrupted. Thereafter, the remaining amount of reaction mixture is injected into the cavity. The invention also relates to apparatus useful in performing the above-described process.

Abstract: The present invention is directed to an apparatus for producing a reaction mixture from at least two fluid components comprising: (A) a storage container for each component; (B) feed pipes leading from each storage container via metering pumps to injection nozzles; (C) return pipes leading from each injection nozzle to the storage containers; (D) the injection nozzles opening into the mixing chamber of a mixhead, the mixhead having an outlet opening downstream of the injection nozzles, each injection nozzle comprising (i) a housing, (ii) a bore arranged in the housing, the bore connected to a feed pipe and a return pipe, (iii) a nozzle needle within the bore, the nozzle needle being provided with (a) an annular groove for connecting the feed pipe and the return pipe, (b) a sealing surface, and (c) a needle spindle, (iv) a sealing surface in the housing, the sealing surface adapted to contact the sealing surface of the nozzle needle, and (v) a central nozzle bore located in the sealing surface (vi) wherein the

Abstract: A process and a mixing head for the production of a reaction mixture comprising at least two reaction components, with a high degree of mixing. By this process, reaction components are introduced, at a high pressure into one end of the mixing chamber of the mixing head, these components being deflected by the front of the discharge piston which forms the opposite end of the chamber, a counterflow forming intensive turbulences on the wall of the mixing chamber and on the boundary surface with the incoming flow before this counterflow exits the mixing chamber at the same end through which it entered the chamber, substantially as a radially-directed, laminar flow.

Abstract: Hydraulically coupled injection nozzles (5,28) and return nozzles (15,38) are used in an apparatus for producing a reaction mixture of fluid components forming foam or a solid material. These nozzles (5,15,28,38) comprise control pins (11,20,34,43) which are designed to be inserted into the openings (6,17,29,40) of the nozzles (5,15,28,38). The ratio between the distances which the control pins (11,20,34,43) travel outside and inside the orifices (6,17,29,40) is adjusted in such a way that, when the nozzles (5,15,28,38) are switched from "mixing" to "circulation" or vice versa, there is a time interval during which all the nozzles (5,15,28,38) are closed.

Abstract: The invention relates to a method and a device for producing a solid-forming or foam-forming flowable reaction mixture by metered injection of flowable reaction components into a mixing zone from which the finished reaction mixture is discharged.

Abstract: The instant invention is directed to a process for filling a cavity with a flowable reaction mixture through an inlet opening located at the bottom of the cavity. The process broadly comprises injecting a relatively small amount of reaction mixture into the cavity to cover the inlet opening with reaction mixture. The injection process is then briefly interrupted. Thereafter, the remaining amount of reaction mixture is injected into the cavity. The invention also relates to apparatus useful in performing the above-described process.

Abstract: Continuous foam blocks with rectangular cross-section are produced on a side-limited conveyor band by feeding a foamable mixture to a cover foil travelling with said conveyor band and covering the free surface of the mixture with a bearing layer not earlier than immediately after the supply of the mixture and not later than before the zone in which a skin would be formed on the free surface of the block.

Abstract: The instant invention relates to an apparatus for the continuous production of foam plastic blocks of a rectangular cross-section, in particular based on polyurethane. The apparatus generally comprises an endless conveyor belt whose upper run is provided with side walls, an unwinding device for a bottom and side sheet to cover the upper run of the belt and the side walls, a levelling device in the form of a roller or a doctor, which extends transversely in relation to the conveyor, a mixture application device and an unwinding device for a sheet to cover the mixture applied.

Abstract: The instant invention is directed to an improved device for mixing liquid reaction components comprising a storage container for each reaction component, a feed pipe leading from each container to a mixing head where the pipe terminates in a pressure controlled injecting jet, and a return pipe containing a shut-off valve, the improvement wherein a pressure adjustable initial stress valve is located in each return pipe. The adjusted initial stress pressure is greater than the solution pressure of the gases or air contained in the reaction components but less than the opening pressure of the injection jet.

Abstract: The instant invention relates to a method and apparatus for measuring the proportion of undissolved gas in a liquid component for the production of foam materials, particularly those based on polyurethanes. The method is based on the equation of state of ideal gases (Boyle-Mariot Law: p.multidot.v = constant) at constant temperatures. The gaseous portion of a liquid component charged with gas increases its volume under expansion according to the above equation. The gas expansion also increases the liquid volume. The differences in the volumes, of the liquid at two differing pressures is therefore a measurement of the quantity of gas present in the liquid. The apparatus consists of a closed graduated measurement vessel being connected to a variable pressure means capable of producing at least two different defined pressures.

Abstract: The two coupled vertical-lift slides of a mixing head for multicomponent plastics are formed with recesses which, in the rest position of the mixing head, form part of the mixing chamber wall so that a stripping rod, whose diameter is greater than the minimum interval between the vertical-lift slides, can be pushed through, preferably perpendicularly of the vertical-lift slides, to scrape out the mixing chamber.

Abstract: The present invention provides a mixing head having vertical lift slides in which the injection pressures can be altered. Each lift slide is provided with a number of injection openings of different diameters arranged in one plane perpendicular to the axis of the slide. The injection pressure is altered by rotating the lift slide to bring a different injection opening into registry with a mixing chamber. The head of each lift slide is provided with a head having change-over detents which mesh with a carrying yoke to facilitate changing injection openings. The lift slides may also be provided with return openings of such diameter that the pressure in the system remains the same whether the slides are in a mixing position or a return position.