| 摘要 |
Outer section and main body each have associated lines for molten plastic. These form a connection for flow, between the screw thread recesses and the screw ante-chamber. In a second position of the outer section relative to the main body, the connection is interrupted in a controlled manner. Outer section (7) and main body (6) each have associated lines for molten plastic (11, 12). These form a connection for flow, between the screw thread recesses (3) and the screw ante-chamber (4). In a second position of the outer section relative to the main body, the connection is interrupted in a controlled manner. The axial cheek (16) is configured to cover and seal the melt line (11) in the end face (19), on making contact with it (19). The outer section (7) is carried with the tip (14). The melt line is formed by bores, of which there are a number, distributed evenly around the circumference of the outer section. They start from the end face, and discharge into the cylindrical inner face of the outer section. The angle between the axis of each bore and the axis of screw rotation, is 30degrees to 90degrees, preferably 45degrees. The melt line (11) comprises grooved channels. It (12) comprises several bores distributed evenly over the circumference of the main body (6), angled as specified above, with respect to the rotation axis. A grooved configuration is also feasible. Main body and tip are integral or screwed together. The main body is permanently screwed to, or permanently attached to the plasticizing- and injection screw. The outer section is hollow, cylindrical. The cheek is conical or spherical. Outer circumference(s) of the outer section have a wear-resistant coating, as does the inner circumference of the outer section. The tip and its seating areas have wear-resistant coatings.
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