Abstract: A split mold for multi-component plastics, especially polyurethanes, with venting channels has heating devices in the zone of the said channels to prevent plastic from entering the channels and thus forming flash on the moldings.

Abstract: To mix two or more fluid plastic components, which react with one another, intimately and abruptly, the components are injected under high pressure and at high velocity into a mixing chamber. To provide greater control of the type of mixing, i.e. to allow control of the spread of the jet and/or the jet volume and the jet energy losses, the components are guided so that they impinge on one another at an angle, preferably an angle which can be varied. To achieve this, and in particular to allow the point of impingement of the jets to be varied, the injection nozzles can be slid or pivoted at right angles to the lengthwise axis of the mixing chamber, and may also be adjustable in the direction of the said axis, and in respect of their distance from the axis.

Abstract: A mixing device for mixing together multi-component plastics materials, for example polyurethane, comprises a mixing chamber into which supply ducts for the components lead and in which a piston is reciprocable between a retracted position in which the supply ducts are in communication with the mixing chamber and a forward position in which the supply ducts are shut off from the mixing chamber. The piston is provided with an axial bore through it connected to a supply of air under pressure to enable air to be supplied into the mixing chamber together with the components for producing plastic foam such as foamed polyurethane.