Composite body forming chamber - has U=section connecting rails with recess in central part opposite thickened portion

摘要

The body is assembled from two or more parts, typically rails, so as to form a hollow space. The connecting components are U-section rails (6), with a central thickened portion (7) extending in the same direction as the flanges. A recess (8) is formed in the central part on the opposite side to this thickened portion, its depth being typically equal to the thickness of the thickened portion. There can be a mushroom-shaped extension on the thickened portion, engaging behind the gap formed between protrusions on the rail-shaped parts.