| 摘要 |
<p>Method for extruding plastic pipes from an extruder nozzle having a number of heating elements (26A, 26B, 26C) which are distributed circumferentially around the extruder nozzle (10A). The wall thickness of the extruded pipe is measured by means of ultrasound in a number of measuring positions (19A, 19B, 19C) distributed around the pipe, said measuring positions corresponding to the number of heating elements in the extruder nozzle and being located on the calibrator sleeve (16) in a vacuum or pressure calibrator (12) forming part of the extruder line. The power of the heating elements is controlled in dependence of measured thickness values for adjusting the surface friction and thus the wall thickness in the sections of the pipe wall, corresponding to the heating elements.</p> |
