| 摘要 |
PURPOSE: To achieve extrusion of a medium and ensure that no melt can reach an outlet opening by permitting the outlet opening of a hollow needle to vary or open/close its cross-sectional surface through a needle core slidably in the hollow needle toward a mold cavity or a recessed portion. CONSTITUTION: A needle core 9 is axially adjusted within a hollow needle 5 by means of an adjusting nut 12, a counter nut 13, and a support collar or support disk 14, such that an outlet opening in the form of a radially directed gap valve 16 is created between the head or plate 10 of the needle core 9 and the opening end of the hollow needle 5. This arrangement is particularly adjusted to a width of less than 0.2 mm by means of the adjusting nut 12, the counter nut 13, and the support collar or support disk 14. Since the gap valve 16 is adjusted to the gap width of less than 0.2 mm, the pressurized medium can reach the mold cavity 4, while it can prevent plastic melt from accumulating at or clogging the gap valve 16. |
