| 摘要 |
The invention relates to an extruder head for extrusion blow-molding plastic containers, comprising a ring-gap nozzle having a mandrel and a ring-shaped nozzle body, an elastically deformable sleeve, and setting devices for deforming the elastic sleeve radially. The sleeve is upwardly and downwardly supported on sliding surfaces and guided in a radially movable manner. Largely wear-free deformations and displacements of the sleeve are possible if according to a first embodiment of the invention, the sleeve is realized from the upper end on the inlet side to the outlet of the nozzle in the form of a cylinder or tube with a longitudinal profile approximated to the shape of the cylinder. The cross-section of the stream of melt exiting from the ring-gap nozzle is shaped by the lower edge of the sleeve located on the inner side of the tube, said sleeve being arranged at the end on the nozzle outlet side. According to another embodiment of the instruction as defined by the invention, the sleeve has a conical widening toward the end on the nozzle outlet side. The sleeve is further developed in such a way that the inside diameter of the sleeve measured on the upper face is smaller than the inside diameter at the nozzle outlet. With an unsymmetrical design of the sleeve, the wall profile of the sleeve andthe height of the points of force application by the setting devices have to be coordinated in a suitable manner in order to assure that when the sleeve is deformed, the upper face of the sleeve guided on a sliding surface of the body of the nozzle will at least approximately maintain its plane parallelism in relation to the sliding surface.
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