Duct connector for leakfree attachment to the curved sidewall of highly flexible trunkline duct

A duct fitting of generally cylindrical configuration for attachment in a right-angle relationship to a relatively large cylindrically-shaped flexible duct having a curved, easily deformed flexible sidewall of insulating material, in which curved sidewall, a hole of a particular diameter has been created, said duct fitting being constructed of an elongate sheet of bendable material that, before being Assembled into a generally cylindrical configuration, had a first long edge cut into a generally sinusoidal configuration, said duct fitting, when formed into a generally cylindrical configuration, having a first end possessing a curvature conforming to the configuration of the curved sidewall of the flexible duct with which it is to be used, said second end of said duct fitting being adapted to receive thereon, a relatively small branch duct to be connected to the flexible duct, said first end of said duct fitting having a plurality of spaced, bendable teeth disposed about its periphery, arranged in a non-planar array, said teeth of said first end being insertable into the hole created in the curved sidewall of the flexible duct, sidewall protection means insertable into such hole, followed by the insertion into the hole of said teeth, said teeth then being bent over into conforming engagement with said sidewall protection means, which has assumed the configuration of the curved interior surface of the flexible ducting, thus to secure the branch fitting to the flexible ducting in a leak-free manner.

A duct fitting of generally cylindrical configuration for attachment in a right-angle relationship to a relatively large cylindrically-shaped flexible duct having a curved, easily deformed sidewall in which a hole of a certain size has been created, said duct fitting being constructed of deformable sheet material that, before being assembled into a generally cylindrical configuration, was defined by an elongate sheet of material having first and second long edges, said first long edge being cut into a generally sinusoidal configuration, with a plurality of short lateral slots formed at spaced locations along said first long edge, said duct fitting, when formed into a generally cylindrical configuration, having a first end possessing a curvature conforming to the configuration of the curved sidewall of the flexible duct with which it is to be used, namely said first end having a curvature involving a pair of oppositely located peaks disposed in a symmetrical relationship, and a pair of oppositely located valleys disposed between said peaks, said second end of said duct fitting being adapted to receive thereon, a relatively small branch duct to be connected to the flexible duct, said first end of said duct fitting having, as a result of such slots, a plurality of bendable teeth arranged in a curving, non-planar array, said teeth being insertable into the hole created in the curved sidewall of the flexible duct and then bent over into a position preventing withdrawal of said duct fitting from the flexible duct, and insertion-limiting means disposed on the exterior of said duct fitting, for limiting the insertion of said duct fitting into the flexible ducting.

A duct fitting of generally cylindrical configuration for attachment in a right-angle relationship to a relatively large, flexible duct having a curved, flexible, easily deformed sidewall, said duct fitting being constructed of deformable sheet material that, before being assembled into a generally cylindrical configuration, was an elongate piece of material having first and second long edges, said first long edge being of a generally sinusoidal configuration, and having therein a spaced series of short lateral slots, a sinusoidal groove disposed in an evenly-spaced relationship to said first edge of sinusoidal configuration, located adjacent the base of said slots, said duct fitting, when formed into a generally cylindrical configuration, having a first end possessing a curvature conforming to the configuration of the curved sidewall of the flexible duct with which it is to be used, namely said first end having a curvature involving a pair of oppositely located peaks disposed in a symmetrical relationship with an intervening pair of oppositely located valleys, said second end of said duct fitting being adapted to receive thereon, a relatively small branch duct to be connected in a leak-free manner to the flexible duct, said slots on said first end of said duct fitting defining a plurality of bendable teeth arranged in a non-planar array, and a first substantially flat ring whose inner diameter is essentially the same as the effective diameter of said sinusoidal groove residing adjacent said teeth, said first ring undertaking a curvature conforming to the curvature of the curved sidewall of the flexible duct, said first ring serving to limit the insertion of said first end of said duct fitting into the hole in the flexible duct, said teeth thereafter being bent over into contact with the curved interior surface of the flexible duct.

The method for connecting a branch duct in a right-angle relationship to a relatively large, flexible duct having a curved, flexible, easily deformed sidewall by the use of a generally cylindrically-shaped duct fitting constructed of deformable sheet material and inserted into a hole of a certain size located in the sidewall of the flexible duct, this method comprising the steps of

• selecting an elongate piece of deformable sheet material having first and second long edges,
• forming said first long edge into a generally sinusoidal configuration, and forming in such long edge a spaced series of short teeth as well as a continuous groove located adjacent the bottoms of said teeth,
• forming said sheet material into a generally cylindrically-shaped duct fitting by placing the ends of the sheet material together in an overlapping relationship,
• placing a flat ring of flexible material around said duct fitting, with the inner circumference of said ring residing in said continuous groove,
• expanding the sheet material outwardly into cylindrical form, so as to cause said flat ring to seat tightly in said continuous groove and thus to undertake a curved configuration,
• securing said overlapped ends tightly together to cause said duct fitting to retain its cylindrical shape,
• said duct fitting having, because of the generally sinusoidal configuration of said first long edge, a first end possessing a curvature conforming to the configuration of the curved sidewall of the flexible duct with which it is to be used,
• inserting said first end into the hole in the sidewall of the flexible duct, and bending the teeth over into tight, closely conforming contact with the interior of said flexible duct,
• said second end of said duct fitting being adapted to receive thereon, a relatively small branch duct to be connected in a leak-free manner to the flexible duct.