| 摘要 |
PROBLEM TO BE SOLVED: To provide a box body using a plastic hollow body sheet which causes no steps when folded and an improvement in the method for manufacturing the same.SOLUTION: A plurality of rectangular blanks are combined at right angles, the marginal part of one blank is folded and welded to the marginal part of the other blank while being pressurized. A weld part is so formed that the marginal part of the folded blank may be flush with the marginal part of the other blank. The weld part of the corner is separated off to a folded piece formation position, and an unseparated part is made as a trunk side wall. Each separated part turns into a folded part jointed to the trunk side wall to block the opening side of the trunk. |
