| 摘要 |
Bottom (1) to a container, box, basket, barrel, cask or the like (8) made of a polymeric material and preferably produced by injection moulding. Material thickening and essentially scalloped, jagged and/or wave-like elevations (5) constitute an integrated part of the upper (3) and/or lower (4) surface of the bottom (1). The height (Fig.12, A-B) of the elevations (5) is 0.5-20 mm representing at least 20 % of the maximum thickness of the bottom (1). Intervening spaces (6) are formed between the material thickening elevations (5). A container (8) including a bottom (1) is produced by injection moulding and is cooled in the mould in such a way that the elevations (5) hold a core temperature exceeding the surface temperature to such an extent that the core shrinkage is larger than the surface shrinkage. A strong inner tensile stress is obtained, whereby the elevations (5) work as pretensioned reinforcing bars. |
