Clip=on flange for rectangular box section duct - has hollow L=section with bar forming channel with double thickness walls housing duct edge

摘要

The clip-on flange is for use at transverse joints between rectangular box section ducts (1) in aerotechnical installations. A length is fitted to each edge of the duct to locate corner pieces (3) and form a continuous square external flange (2) for a sealed (23) and clipped (20) joint. The cross-section approximates to a double walled 'L'. The leg (10, 11) is tapered and hollow to accommodate corner pieces (3), returns terminally square (5) to locate connecting clips (20), and is shaped (22) to locate a seal (23). The bar is formed by a return-folded doubling of both the walls (10, 11) of the leg to derive a narrow channel (6). The channel (6) houses the edge (7) of the duct with a cranked flap (17) engaging a reciprocal duct rib (19) to lock the assembly. The sheet metal layers (12, 13, 16) forming the double walls of the channel (6) are crimped (14, 18) together.