| 摘要 |
<p>A melt indicator for plastics used especially in connection with resistance wire, electro-fusion welding of PE-pipes and formed articles, shows that a suitable state is reached for safe bonding. The indicator made of the same material as plastics to be welded, is sunk in the wall of the plastic piece (2) and comprises a segmented cylindrical mandrel (1) protruding from the base of the indicator recess delineated by a circular groove (3). Preferably the base of the indicating recess has a spherical surface, being generated by the surface of the base of sectional grooves (4) and by the surface of the base of the cylindrical circular groove (3) surrounding the mandrel (1) segmented by sectional grooves (4). The lowest part of the indicator recess is found 1mm above the heating coil (5). The upper end of the segmented mandrel (1) is found at the level of the external surface plane of elements (2) to be welded. The circular groove (3) surrounding the segmented mandrel (1) is constructed with internal cylindrical and external conical side walls narrowing towards the surface of the base.</p> |
