Plasticization and injection unit for rubber injection molding machines comprises plasticizing cylinder feeding side of second injection piston via inlet from which channel extends through piston to outlet valve

摘要

A plasticizing cylinder(8) with a plasticizing and injection screw(9) having a tip forming a first injection piston(10) enters the side of a second injection piston(5) moved axially by a drive unit(6). A channel extends through the second piston from the mouth of the plasticizing cylinder to a valve(12) at the outlet end facing an injection molding tool. The plasticizing cylinder area(8,9,10) and the channel area of the second injection piston(5) are heated to different temperatures. The second injection piston may be either conical or have a flat front end. The valve may comprise either a flow operated non-return valve(12) or an externally operated closure member. An integral unit is formed by the plasticizing cylinder(8), its drive unit(11) and the second piston so that they all move together. Pressure cylinders form the drive units(6,11) for both the plasticizing cylinder and second piston.