Abstract: An apparatus for proportioning reaction mixtures, particularly for the manufacture of hard polyurethane foam. The apparatus includes two proportioning cylinders each for proportioning one of the components to a mixing head. The pistons of the two proportioning cylinders can be operated alternatingly for filling the cylinders with the compound and subsequently ejecting the component from the cylinders. Double-acting hydraulic cylinders driven by a common hydraulic pump operate independently from each other the proportioning pistons of the two proportioning cylinders. A servo-controlled proportional valve is provided in each of the connecting lines between the hydraulic cylinders and the hydraulic pump. The control cycles of the proportional valves determining the ejection of the two cooperating proportioning cylinders are adjusted relative to each other so as to temporarily overlap.

Abstract: A mixing and extruding nozzle for two reactant components has a housing formed with a mixing chamber, a pair of parallel and oppositely directed faces flanking and turned away from the chamber, respective injection passages having inner ends opening into the chamber and outer ends opening at the respective faces, and respective outwardly open grooves in the faces offset from the passages. A valve-type rocker pivotal relative to the housing about an axis perpendicular to and traversing the two faces and offset from the passages and grooves has two like halves each formed with a face confronting the respective housing face and a feed passage opening at the respective rocker face offset from the axis.