| 摘要 |
<p>PURPOSE:To provide a case or the like made of a thermoplastic resin sheet and is free from any welded corner projection, by folding a thermoplastic sheet to form a gusset with ?-shape in cross section, putting other sheets on and under the above, mentioned sheet, and welding them. CONSTITUTION:The sheet 4a that will constitute one side of the desired case is placed on a heating plate 2, and the gusset 6 that is formed to have a ?-shaped cross section is mounted to the three sides (b) of an intermediate body 3 and is put on the sheet 4a. Then the sheet 4 that will constitute the other side of the desired case is placed thereon, then an upper heating plate 1 is placed thereon, and while the heating plate 1 is being pressed toward the heating plate 2, a high- frequency electric current or heating electric current is passed through the heating plates 1, 2 thereby welding the thermoplastic sheets 4, 4a to the edges 6a, 6b of the gusset 6.</p> |
