| 摘要 |
The invention concerns a device comprising a frame (1) with two horizontal support surfaces (6A, 6B) and two sloping support surfaces (6C, 6D) adapted to co-operate with matching support surfaces (12A, 12B, 12C, 12D) integral with the cover element (2). The sloping support surfaces (6C, 6D, 12C, 12D) slope downwards towards the horizontal support surfaces (6A, 6B, 12B, 12A) and the frame (1) is provided, in the proximity of each sloping support surface (6C, 6D), with an internal projection opposite the corresponding sloping support surface (6C, 6D), a lateral counter-support surface (9C, 9D) which on a plane is obliquely oriented relative to the lateral surface (8) of the frame adjacent to the two sloping surfaces (6C, 6D), the two counter-support surfaces (9C, 9D) extending towards the inside of the frame along converging directions and being designed to co-operate with matching counter-support surfaces (13C, 13D) integral with the cover element (2). |
