Folded-seam connection, method of producing it and device

Abstract

In ventilation and air-conditioning technology, so-called spiral pipes have to be joined together in a tightly sealed manner at widely differing angles, which is generally carried out by segment bends and pipe sections. An improved, durable seal of folded-seam connections is achieved by a flange-like double fold which is arranged at a first pipe end and which is surrounded on the outside at least in part with positive locking and with a continuous metal seal, by a second double fold at the second pipe end.

1 . A folded-seam connection with a high degree of sealing tightness between two ductile metallic pipes, pipe sections, pipe segments or pipe bends used for conveying flowing gases, characterized in that a flange-like double fold is provided at a first pipe end and is surrounded by a second double fold of the second pipe end, at least in part form fittingly and with an all around continuous metal seal.  
   
   
       2 . A folded-seam connection according to  claim 1 , characterized in that the inner flange-like double fold has an air gap between its flange parts, and at least lateral faces abut in a springing manner in the interior of the outer double fold.  
   
   
       3 . A folded-seam connection according to  claim 1 , characterized in that at least one continuous insulating layer is provided in part between the flange-like double fold and the second double fold enclosing the latter.  
   
   
       4 . A method of producing metallic sealing folded-seam connections, at least partly positively locking, on ductile pipes and/or pipe-bend segments on a flanging and/or folding/closing machine having rotatably mounted shaping rollers and delivery rollers displaceable in one plane, wherein the two rollers are driven by a motor and project from a machine bench, characterized in that 
 in a first method step a flange-like double fold is produced at a first pipe end;    in a second method step a folding tab with an internal diameter larger than the flange-like double fold is formed on the other pipe end to be joined;    in a third method step the folding tab is pushed over the double fold and after that;    the projecting part of the folding tab is pressed and clamped against the flange-like double fold in an abutting manner, so that the latter is surrounded in a sealed manner.    
   
   
       5 . A method of producing a double fold at a first pipe end according to  claim 4 , characterized in that 
 in a first method step the first pipe end is put onto a rotating first shaping roller fixed in the axial position on the machine bench, with peripheral contact on the inside of the pipe and said roller,    in a second step a second shaping roller likewise rotating is pushed in the tangential plane thereof until it touches the pipe end on the outside so that the latter jointly rotates in synchronism,    in a third step the second shaping roller is pushed stepwise in the tangential plane by the width of the double fold against the first shaping roller so that a continuous folding tab is impressed at the pipe end; and    in a fourth step a lower delivery roller is pushed further in the direction towards the shaping roller in a second plane situated at a lower level than the tangential plane by at least twice the thickness of the pipe material, wherein a lower roller is drawn back under the second shaping roller in synchronism in the opposite direction, so that the folding tab is closed and a flange-like double fold is formed.