| 摘要 |
The lower of a pair of welding electrodes for coating or enclosing a reinforcement material such as carton, leather, etc., between two bands of synthetic thermoplastic for document cases, book covers, foodstuff packets, etc., is cut away relatively to the upper electrode in the zone which during working, is adjacent to the edge of the reinforcement material and extends inwards. When the lower electrode is a plate, in the zone opposite to the side of the upper electrode which is close to the edge of the reinforcement, a cutout is machined in the plate over part of its thickness. When the electrodes are rods, in a direction outwards from their centre line, the lower electrode is narrower than the upper. When the upper electrode is a cutter with a side face, the face of the lower electrode adjacent to the face of the upper electrode away from its cutting edge, is offset inwards from that face. Method prevents the formation of bubbles, wrinkles and holes with other deformation in the zones adjacent to the weld, due to overheating, by restricting lateral radiation from the electrodes. |
