| 摘要 |
The invention relates to a co-injection nozzle (2) for an injection moulding device for producing multi-layered injection-moulded products, said nozzle comprising: a central bore (20); a valve needle (10) for opening and closing a nozzle opening (30), which needle is held in an axially movable manner in the central bore (20); an annular inner melt channel (23) for the first melt (A); an annular central melt channel (24) for a second melt (B); and an annular outer melt channel (25) for the first melt (A), the inner, central and outer melt channels (23, 24, 25) being fluidically combined in the region of the nozzle tip (9) in order to form a concentrically-layered melt stream. According to the invention, the co-injection nozzle (2) has a back-flow barrier (40), integrated into the central bore (20), for the second melt (B), this barrier being formed by a cut-out (42) in the valve needle (10) and by a melt channel (41) for the second melt (B), which channel penetrates the central bore (20). In the open position of the back-flow barrier (40), the cut-out (42) is located with respect to the penetrating melt channel (41), such that the second melt (B) can flow through the penetrating melt channel (41), whilst flowing in the central bore (20) past the valve needle (10). |
