Injection-molding station for the manufacture of multilayer preforms

An injection-molding station for the manufacture of multilayer preforms comprising:

• an injection-molding machine (2) having at least one injection-molding cavity (1);
• at least one multi-component nozzle (3);
• at least two melt accumulators (4, 5) connected thereto;
• at least two plasticizer units (6, 7) for charging them;
• a control unit (8);
• and
• actuators (15, 18) that can be activated independently of one another by the control unit (8),
• wherein the at least one multi-component nozzle (3) is constructed as a shutoff nozzle with at least two melt channels (9, 10) disposed concentrically relative to one another, at least in portions, connected to the melt accumulators (4, 5) and merging with one another inside the at least one multi-component nozzle and with two closing slides (17, 19), which can be separately activated, associated therewith;
• wherein the actuators (15, 18) act on the slides (17, 19) in such a way that the melt channels (9, 10) respectively have an infinitely variable passage cross section;
• wherein the melt accumulators (4, 5) are constructed as cylinder accumulators with a proportional actuator (26, 27) that is associated with the respective piston (22, 23) and can be activated by the control unit (8);
• wherein the control unit (8) comprises a memory unit for coordinated movement or position profiles of the at least two closing slides (17, 19) and the at least two melt-accumulator pistons (22, 23);
• wherein the drives of the plasticizing units (6, 7), the actuators (15, 18) of the closing slides (17, 19) and the proportional actuators (26, 27) of the melt-accumulator pistons (22, 23) are of electromechanical construction;
• wherein the closing slides (17, 19) are constructed as shutoff needles (13, 14) disposed concentrically relative to one another wherein a first of the shutoff needles is constructed as a hollow needle (12);
• and
• wherein both the outside and inside of the hollow needle (12) adjacent to the nozzle mouth (54) taper toward the mouth.