| 摘要 |
The disclosure relates to an envelope to a cowper or a similar apparatus, comprising a wall (1) made with welded metal sheet, characterized in that it comprises a second wall (4) of welded metal sheet, which is arranged outside and parallel to the first wall, those two walls delimiting therebetween a space (5) filled with a filler material (6) consisting of light alloy shot, for example aluminium or aluminium alloy shot, embedded in a thermosetting resin binder. The operation life of said apparatuses is thus considerably improved and the lining and reinforcing process is relatively easy to implement. |
