| 摘要 |
<p>The invention provides an annular die for an extruder head for extruding thermoplastic tubes having a die gap which can be uniformly enlarged or reduced by displacing relative thereto a conical die core, said die having a multistage sleeve, an inner stage of which has a uniform boundary surface, and at least one outer stage of which has a boundary surface having a non-uniform shape in the circumferential direction of the die, said stages having effective edges which, on vertical adjustment of the die core, form the outer boundary of the die gap independently of each other.</p> |
