초록 ▼

The invention concerns a method of forming a flange or bellows in a plastic tube. The tube is preheated at a precise area and gripping dies are used to compress the heated area. Upon compression, the heated area is forced to bulge out and fold to form the flange or bellows. A mandrel inserted into t

The invention concerns a method of forming a flange or bellows in a plastic tube. The tube is preheated at a precise area and gripping dies are used to compress the heated area. Upon compression, the heated area is forced to bulge out and fold to form the flange or bellows. A mandrel inserted into the tube prior to compression ensures that the tube bulges outwardly. The invention may be used to form a variety of flanges, rims or bellows on plastic tubing. It is particularly useful in forming retaining rims on polyethylene tubing used for gas tank vents. Exposure to gasoline may cause such tubes to swell or bend. With a retaining rim formed in accordance with the present invention such swelling or bending can readily be accommodated.

대표청구항 ▼

A method for forming a flange or bellows in a plastic tube comprising: inserting a mandrel inside a plastic tube; gripping said tube with at least two gripping dies, said gripping dies initially spaced apart; heating the tube between the two gripping dies until the wall portion of said tube between

A method for forming a flange or bellows in a plastic tube comprising: inserting a mandrel inside a plastic tube; gripping said tube with at least two gripping dies, said gripping dies initially spaced apart; heating the tube between the two gripping dies until the wall portion of said tube between said gripping dies is foldable, moving said gripping dies relatively toward each other to form such flange or bellows; controlling the extent of movement of such gripping dies so as to avoid the interior walls of the flange or bellows from sticking to each other, and providing the gripping dies with opposed annular ridges which are adapted to abut when the dies are moved toward each other.