Device for preparing and ejecting a chemically reacting mixture

A device for preparing a chemically reacting mixture, and for ejecting the mixture into a mold, the mixture comprising at least two components, in particular a mixture of isocyanate and a polyol that reacts completely to form polyurethane, the device comprising a mixing head having an outwardly open first bore, a reciprocable ram coupled to said head, said ram having an ejector rod axially movable in said bore for ejecting the mixture from said chamber when in an extended position, said rod defining with said bore a mixing chamber in a retracted position of said rod, said head having inlet passages for inletting the respective components into said chamber for preparing the mixture, means associated with said ram for axially moving said rod between said positions for ejecting the mixture out of said chamber, said mixing head having an outwardly open second bore intersecting with said first bore, ceramic body means located in said second bore and comprising a pair of stripper elements having abutting end walls shaped to together form an opening of substantially the same shape and size as that of said rod, said second bore being so positioned relative to said passages that said rod extends through said opening in said retracted position of said rod, whereby any film or residue of the mixture adhering to said rod is stripped from said rod by said ceramic body means as said rod is retracted from said extended position.