Device for connecting a tube and a sheet metal element

Process for connecting angularly a tubular shape and a two-sheet sheet metal element, wherein the following steps are performed successively:

• (a) a throughgoing opening is made in each of the two sheets of said two-sheet sheet metal element, said openings having dimensions at least equal to the outside dimensions of said tubular shape;
• (b) the free end of said tubular shape is chamfered;
• (c) a ring, whose outside dimensions are approximately equal to those said openings whose inside dimensions are less than the outside dimensions of said tubular shape, is engaged into said openings in said two-sheet sheet metal element, said ring having a plane section at a first end and a conical bore at the other end and the engaging relationship being such that said other end of said ring is flush with one outside face of said two-sheet sheet metal element;
• (d) said ring is locked axially;
• (e) said tubular shape is force-fitted into said ring and said openings in said two-sheet sheet metal element, by first presenting said chamfered free end of said tubular shape opposite said bored end of said ring, the fitting being continued until said chamfered free end of said tubular shape projects beyond one outside face of said two-sheet sheet metal element;
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• (f) said free end of said tubular sheet is flanged outwardly on said two-sheet sheet metal element into the shape of a round collar in a corolla onto said outside face of said two-sheet sheet metal element.

A method of connecting a tubular shape to a sheet metal element comprising two spaced sheets of metal, said method comprising the steps of:

• (a) forming a through-hole through each of said two spaced sheets of metal, said through-holes having internal dimensions slightly larger than the external dimensions of the tubular shape to be connected to the sheet metal element;
• (b) positioning a ring in said through-holes such that one end of said ring is flush with the outer surface of one of said two spaced sheets of metal and said other end of said ring projects outwardly from said outer surface of said other of said two spaced sheets of metal toward said tubular shape, said ring having an outwardly opening internal chamfer at said other end and having both external and internal dimensions closely matched to those of said tubular shape;
• (c) gripping said ring in a die which provides peripheral support of said ring from said other end of said die to a point slightly spaced from the outer surface of said other of said two spaced sheets of metal;
• (d) providing an external chamfer on the leading end of said tubular shape which is sized and shaped to match the outwardly opening internal chamfer at said other end of said ring;
• (e) forcing said tubular shape axially through said ring until said tubular shape projects beyond said one of said two spaced sheets of metal, during which step said die causes said tubular shape to distort radially inwardly as said tubular shape passes from said other end of said die to said point, the absence of said die between said point and said other of said two spaced sheets of metal permits said tubular shape to recover elastically, distorting said ring outwardly to form a first collar abutting said other of said two spaced sheets of metal between said point and said other of said two spaced sheets of metal and to come into close contact with the inner surfaces of said through-holes in said two spaced sheets of metal;
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• (f) turning outwardly the portion of said tubular shape which projects beyond said one of said two spaced sheets of metal to form a second collar abutting said one of said two spaced sheets of metal.