| 摘要 |
PURPOSE:To enable to rapidly and highly accurately realize various forms of bending and consequently remarkably improve the work efficiency by a method wherein the bent edges of a tubular body are mechanically formed in advance on both the upper and lower edges of a flate plate-shaped plastic sheet. CONSTITUTION:Four folding lines 1' corresponding to the respective corners are arranged in parallel to one another in the direction of the width on a flat plate-like plastic sheet 1 cut in the pre-desired size. At the same time, a bent edge 2 with a hook-shape in cross section and a bent edge 2' with an L-shape in cross section are respectively heated and bent with an impulse heater or the like at the upper edge and the lower edge of the sheet 1. Neater corners can be obtained by providing a cut of notch 1'' at the position of each folding line 1' in the lower bend edge 2'. The design of the drum of a vessel to be formed can be changed into a polygonal tube such as trigonal tube, hexagonal tube or the like or a circular tube. |
