Meshing cog-wheel injection unit with lateral sealing and scropers

Abstract

An injection unit intended to inject, for example, rubber into a mold comprises in principle two driven cog-wheels, which are located each in a hollow space in the unit housing and mesh with each other, and which in an injection chamber located in direct connection to the engagement zone of the cog-wheels subjects material fed-in to a high pressure, so that the material is pressed out of the injection chamber to a mold. Due to the high pressure, sealing problems arise which according to this invention are solved in that in the housing of the injection unit plane sealings are provided for co-operation with peripheral side portions of the respective cog-wheel, and that at least in the sides of the cog-wheels or in the surfaces of the plane sealings facing to the cog-wheels grooves extending all about are located radially inside the base circle of the cog-wheels for taking up possible material leaking in between the cog-wheels and the plane sealings, and that in connection to the respective groove, in the rotation direction of the cog-wheels after the injection chamber, means are provided for guiding said material in between the cogs of the cog-wheels and, thus, for returning the material to the injection chamber.