| 摘要 |
<p>The invention proposes apparatus for testing plastic profiles or sections, particularly extruded polyethylene tubes which have been cross-linked by radiation, although the application of the invention is not restricted to that field. An electrode at a high potential and a grounded electrode are provided and surround the moving plastic section. A probe consisting preferably of a metal braid is disposed inside the profile or section adjacent to the apparatus and is preferably magnetically held and is not directly conductively grounded to the outside. Defects such as electron punctures in the wall of the plastic profile or section are detected by the breakdowns which are effected at the locations of said defects. It will be understood that the apparatus proposed by the invention can also be used to detect the location of other defects, such as contraction holes, inclusions, bubbles etc., and to deliver control signals to suitable devices for marking, rejecting etc.</p> |
