Method and preprocessed tube for producing a tube with a bent progression or a bend embodied as a traverse progression

Abstract

A method and a preprocessed tube for producing a tube with a bent progression or with a bend embodied as a transverse progression. For the bent position of the tube or for each fold of the transverse progression, two miter cuts are made into an essentially straight tube, thus creating two tube sections with miter cut surfaces extending along the cutting planes and a cutting wedge. The miter cuts are placed according to the invention such that the cutting planes intersect at a point located inside the tube wall, and at this point a bendable bar is left intact connecting the two tube sections. A folding of the miter cut surfaces of the two tube sections onto each other around the bar acting as a hinge then allows both tube sections to be welded together all around their miter cut surfaces. Preferably an additional centering aid in form of a protrusion and a form-fitting recess is provided in the two opposite miter cut surfaces.

1 . A method for producing a tube with a folded progression of a bend formed as a transverse progression, comprising: making two miter cuts at a first position of a straight tube to be folded or for each fold of the transverse progression, resulting in two tube sections with miter cut surfaces extending along faces of cutting planes and a cutting wedge, the miter cuts are placed such that the cutting planes intersect at a point located inside the tube wall and at this point a bendable bar is left intact connecting the two tube sections, removing a cutting wedge from the two tube sections, bending the miter cut surfaces to each other at the miter cut surfaces, and connecting the miter cut surfaces to one another by welding around. 
   
   
       2 . A method according to  claim 1 , further comprising, at a location of the miter cut surfaces of the two respective tube sections spaced apart from the bar, when making the miter cut making at least one protrusion at the miter cut surface of one of the two tube sections and making at least one recess as a form-fitting counterpart of the protrusion into the miter cut surface of the other of the tube sections. 
   
   
       3 . A method according to  claim 2 , wherein the protrusion and the recess are provided at the miter cut surfaces of the two tube sections at a position approximately diametrically opposite to the bar. 
   
   
       4 . A method according to  claim 2 , wherein the protrusion comprises a triangular or rounded pin and the recess comprises a triangular or groove-shaped notch. 
   
   
       5 . A method according to  claim 1 , wherein the miter cuts are made such that the cutting wedge first remains in the tube via not-severed or incompletely severed holding points. 
   
   
       6 . A method according to  claim 1 , further comprising producing the miter cuts via laser radiation, via water jets, or by plasma cutting. 
   
   
       7 . A method according to  claim 1 , wherein a plurality of the miter cuts are made in the tube in order to achieve a tube progression bent in one or more spatial directions. 
   
   
       8 . A method according to  claim 7 , wherein a placement of the miter cuts and the welding of the miter cut surfaces to each other occur in a linked automatic process. 
   
   
       9 . A preprocessed tube for producing a tube with a bent progression or with a bend embodied as a transverse progression, at least two tube sections ( 1 ,  2 ), which are separated by two miter cuts forming a cutting wedge between the tube sections ( 1 , 2 ) and one miter cut surface at each of the tube sections ( 1 ,  2 ), the miter cuts are placed such that the cutting planes ( 3 ,  4 ) intersect at a point located inside a tube wall of the tube, and a bendable bar ( 5 ) that remains at this point, connecting the two respective tube sections ( 1 ,  2 ). 
   
   
       10 . A preprocessed tube according to  claim 9 , wherein at the point of the miter cut surfaces ( 6 ,  7 ) of the two respective tube sections ( 1 ,  2 ) spaced apart by the bar ( 5 ), at least one protrusion ( 9 ) is provided at the miter cut surface ( 7 ) of one of the two tube sections ( 2 ) and at least one recess ( 8 ) as a form-fitting counterpart to the protrusion ( 9 ) is provided in the miter cut surface ( 6 ) of the other one of the tube sections ( 1 ). 
   
   
       11 . A preprocessed tube according to  claim 9 , wherein the cutting wedge remains fastened to the tube by holding points not-severed or incompletely severed, which can easily be removed.