Abstract: The invention relates to a process and a device for the production of mouldings containing a layer of polyurethane in shot operation, in which a gas stream is introduced into the flow channel of the spray device in at least two positions.

Abstract: The invention relates to a method and device for partially or completely foaming the hollow spaces in the ballast structure of a ballast bed, below which a subgrade (7) is located, having a reactive plastic, wherein the reactive components are mixed in a high-pressure mixer (1,26) and wherein the start time for the reactive mixture (4) is adjusted such that the foaming process substantially only begins when the reactive mixture has reached the subgrade (7).

Abstract: The invention relates to a process and a device for the production of mouldings containing a layer of polyurethane in shot operation, in which a gas stream is introduced into the flow channel of the spray device in at least two positions.

Abstract: Cellular or compact polyurethane moldings are produced by conveying at least one isocyanate component and at least one polyol component by a metering machine in dispensing manner into a mixing chamber via component lines to form a polyurethane reaction mixture. Subsequently, the polyurethane reaction mixture is discharged from the mixing chamber into a mold. The pressures of the components are registered by means of pressure transducers in the component lines and are transmitted to a monitoring device. The temporal profiles of the pressures are compared with reference pressure values stored in the monitoring device. A malfunction is signalled in the event of deviation of at least one of the measured pressure profiles from the reference pressure profile beyond a predetermined tolerance threshold.

Abstract: The present invention relates to a method for the continuous mixing of at least one polyol component and at least one isocyanate component and optionally additives to form a polyurethane reaction mixture in a stirrer mixer with an axially conveying stirrer.

Abstract: Molded articles comprising at least one layer of polyurethane are produced in a batch process by mixing polyurethane-forming components to form a reactive mixture that is flowed through a channel having at least one opening through which a gas is introduced and sprayed on a substrate surface. The device suitable for carrying out this batch process includes a cylindrical mixing chamber, a flow channel through which the reactive mixture flows and is sprayed onto the surface of a substrate where it cures thereon. The flow channel is cleaned by a stream of gas.

Abstract: Polyurethane moldings are produced by conveying in shot operation at least one isocyanate component and at least one polyol component for a predetermined time-interval &Dgr;t into a mixing chamber with predetermined volumetric flow-rates {dot over (V)}s/iso for the isocyanate and {dot over (V)}s/polyol for the polyol and with predetermined pressures ps/iso for the isocyanate and ps/polyol for the polyol, mixing those components in a mixing chamber, and discharging the polyurethane reaction mixture into a mold. Prior to shot operation, the components are conveyed in a circuit through circulation lines between the mixing head and the respective component storage vessels. The pressures of the components are measured by means of pressure sensors and are transmitted via pulse lines to a control device.

Abstract: Plastic moldings reinforced with long fibers are made without the risk of forming loops in a continuous thread or roving fed to a cutting unit at the end of a mold filling operation or tearing thereof during renewed start-up for the next molding filling operation, even at a relatively high take-off speed of the continuous thread. This is achieved by keeping the continuous thread permanently under tension pneumatically against the conveying direction. The device useful for carrying out this process is equipped with at least one tensioning air inlet in the guide for the continuous thread or roving.

Abstract: The present invention relates to a method for the continuous mixing of at least one polyol component and at least one isocyanate component and optionally additives to form a polyurethane reaction mixture in a stirrer mixer with an axially conveying stirrer.

Abstract: The present invention relates to a process for the continuous production of polyurethane foam from at least one polyol component and at least one isocyanate component in the presence of water as a blowing agent and optionally further additives, in which, the process steps of mixing and nucleation are separated spatially from one another, such that the components are mixed with one another initially, and bubble nuclei are generated in the polyurethane reaction mixture.

Abstract: Filler-containing molded parts or articles are produced from a free-flowing reaction mixture, e.g. of polyol and isocyanate, in a manner which permits the changeover to a different filler content to be carried out more rapidly and, possibly, without material loss. This is achieved by dividing at least one of the reaction components into at least two portions, at least one of which is charged with filler, by adjusting the mixing ratio of these portions and hence the filler content of the finished molded part. At least two storage vessels are provided for at least one of the reaction components. Adjustable metering devices are arranged between these two storage vessels and the mixing device.

Abstract: Plastic moldings reinforced with long fibers are made without the risk of forming loops in a continuous thread or roving fed to a cutting unit at the end of a mold filling operation or tearing thereof during renewed start-up for the next molding filling operation, even at a relatively high take-off speed of the continuous thread. This is achieved by keeping the continuous thread permanently under tension pneumatically against the conveying direction. The device useful for carrying out this process is equipped with at least one tensioning air inlet in the guide for the continuous thread or roving.