Multi-orifice injector nozzle for injection molding machine

In an injection molding machine having an injection mold with a plurality of injection ports for the simultaneous injection of plastic material therethrough, and an injection unit with a plastification cylinder for supplying plastified material to the injection mold, a multi-orifice injector nozzle attachment for the injection unit adapted, for example, for the processing of clear, temperature-sensitive plastic materials, the attachment comprising in combination:

• a nozzle head in the form of a split block constituted by two block halves joined together along flat clamping faces defining a central separation plane;
• a system of flow channels extending through the nozzle head in alignment with its separation plane, so that the channel walls are constituted jointly by the contiguous block halves, the channel system including:
• a main channel entering the nozzle head from one side thereof;
• three parallel smaller injection channels leaving the nozzle head on the side opposite the main channel;
• a primary channel bifurcation having an entry portion communicating with the main channel and two exit portions opening into two intermediate channels;
• two transversely spaced secondary channel bifurcations, each having an entry portion communicating with one of said intermediate channels and two exit portions of which the outer one leads to the respective outer injection channel and the inner one coverges with the inner exit portion of the other secondary bifurcation;
• and
• a central channel junction having two entry portions communicating with said converging inner exit portions and an exit portion opening into the central injection channel;
• and wherein
• the entry and exit portions of the several channel bifurcations and of the channel junction have curved, smoothly continuing wall outlines and gradual diameter transitions, free of recesses, for an even flow of plastic material therethrough;
• the nozzle attachment further comprising:
• means for removably connecting the nozzle head to the discharge end of the plastification cylinder, so that its main channel sealingly communicates with said cylinder;
• and
• means for clamping together the two block halves of the nozzle head so as to establish hermetic contact between their clamping surfaces along the outline of said channel system.