Mixing head for producing a preferably chemically reactive mixture of

Abstract

A mixing head essentially comprises a housing with a mixing chamber which has inlet orifices for the individual plastics components and an outlet orifice for the plastics component mixture. In the mixing chamber is located an expulsion plunger of identical cross-section, which plunger is connected to a working piston which can be actuated by a pressure medium, the plunger being movable to and fro between a mixing position, which leaves the inlet orifices open, and a position in the region of the front outlet orifice, in which it seals the inlet orifices from the mixing chamber. The mixing head moreover has a restrictor which can be pushed into and out of the mixing chamber by a pressure medium. In the direction of motion of the expulsion plunger for reaching the mixing position B, the working piston displaces, starting shortly before one extreme position and ending upon reaching this extreme position, a pressure medium from the pressure chamber in front of its control surface facing away from the expulsion plunger, whereby the piston allocated to the restrictor can be moved so as to push the restrictor into the mixing chamber. For moving the expulsion plunger into the expulsion position, the working piston can be subjected to pressure medium via two connections, of which one connection can be sealed shortly after the working piston leaves its extreme position and at the same time the restrictor can be pushed out of the mixing chamber, while thereafter the other connection can be subjected to pressure medium.