Abstract: An air duct connecting assembly which consists of sleeve-like male and female connectors. The connectors, which are fabricated from a resilient sheet material, are manipulated from generally flat rectangular blanks into their sleeve-like configurations and are retained therein by the use of lock-tab and matching slot arrangements. One portion of each connector is adapted for insertion into the end of a tubular air duct section, two of which are to be connected, and each has means for mechanically joining the connector to the duct. The other portions of the connectors are adapted to be mated in male and female telescoped relationship. Means are provided on the mating portions of the male and female connectors for locking the connectors in their telescoped relationship.

Abstract: Thin-walled metal duct particularly useful for heating and air-conditioning purposes is usually made by grooving, spiral wrapping, and seaming strips of thin metal sheet. The resultant tubular form provides the necessary rigidity to resist collapse of the tubular form. In the past, at least one end of the ribbed tubular ducts have been reformed to permit the ducts to be joined together. The end reforming techniques of the past have resulted in reformed ends having insufficient rigidity and strength to resist the abuse the ducts frequently receive in shipping, storing, handling, and installation.The present product, method, and apparatus provide a ribbed thin-walled tubular duct having reformed ends with rigidity and strength superior to the prior art products. This achievement is accomplished in the present invention by moving more metal into the end portion of the duct prior to reforming the end portion, thus reinforcing the end portion of the duct.

Abstract: Disclosed herein is rectangular thin walled metal duct easily bendable without significantly changing the cross-sectional area at the bend. Also disclosed are methods and apparatus for forming this rectangular duct and flat/oval duct from round duct having grooves spiraling therearound.