Process for manufacturing powder-filled welded tubes, such as flux-cored welding wires

Abstract

Process for manufacturing a welded tube containing filling elements, in which a long thin metal sheet is supplied continuously and formed into a gutter shape, into which the filling elements are introduced. Next, the sheet thus filled is made substantially into the form of a tube by bringing its two longitudinal edges close together until they are in contact or almost in contact with each other. According to the invention, the tube undergoes an axial rotation through an angle of between 45° and 110° to the vertical and the two longitudinal edges of the tube are welded together by a laser beam. Application of the process to the manufacture of flux-cored welding wire and the flux-cored wire thus obtained.

1 . Process for manufacturing a welded metal tube containing filling elements, in which the following successive steps are carried out: 
 a) a long narrow metal sheet having two longitudinal edges is continuously supplied;    b) at least one part of said long narrow metal sheet is made in the form of a gutter by bringing one of its two longitudinal edges close to the other;    c) filling elements are introduced into the gutter-shaped metal sheet;    d) at least one part of said long narrow metal sheet filled at step c) is made substantially in the form of a tube by (continuing to bring one of its two longitudinal edges closer to the other until said two longitudinal edges are in contact or almost in contact with each other,    characterized in that, after step d):    e) the tube containing the filling elements is made to undergo an axial rotation through an angle between 45° and 110° to the vertical; and    f) said two longitudinal edges of the tube that have been brought into contact with each other in step d) are welded by a laser beam.    
     
     
         2 . Process according to  claim 1 , characterized in that the tube undergoes full-penetration or almost full-penetration welding.  
     
     
         3 . Process according to  claim 1 , characterized in that, in step e) the tube undergoes an axial rotation through an angle between 60° and 105° to the vertical.  
     
     
         4 . Process according to  claim 1 , characterized in that, in step e), the tube undergoes an axial rotation through an angle between 80° and 100° to the vertical.  
     
     
         5 . Process according to  claim 1 , characterized in that, in step e), the tube undergoes an axial rotation through an angle between 85° and 95° to the vertical.  
     
     
         6 . Process according to  claim 1 , characterized in that, in step e), the tube undergoes an axial rotation through an angle of around 90° to the vertical.  
     
     
         7 . Process according to  claim 1 , characterized in that, during steps a) to f), the metal sheet is furthermore made to undergo a continuous translational displacement movement, for example by means of motorized rotary drive rollers.  
     
     
         8 . Process according to  claim 1 , characterized in that the filling elements occupy up to 50% of the internal volume of the tube.  
     
     
         9 . Process according to  claim 1 , characterized in that, after step f), the welded tube obtained is wire-drawn and/or rolled.  
     
     
         10 . Process according to  claim 1 , characterized in that the welded tube obtained is a flux-cored arc welding wire.  
     
     
         11 . Flux-cored arc welding wire formed from an external metal sheath containing powdery and/or granular filling elements, said external sheath having a full-penetration longitudinal weld seam, characterized in that it is obtained directly by the process according to  claim 1 .  
     
     
         12 . Flux-cored wire according to  claim 11 , characterized in that less than 2% of the filling elements that it contains are damaged during the welding of said tube.  
     
     
         13 . Flux-cored wire according to  claim 11 , characterized in that less than 1% of the filling elements that it contains are damaged during welding of said tube.  
     
     
         14 . Flux-cored wire according to  claim 11 , characterized in that less than 0.6% of the filling elements that it contains are damaged during the welding of said tube.  
     
     
         15 . Flux-cored wire according to  claim 11 , characterized in that it comprises a steel sheath and/or it contains rutile as filling element.  
     
     
         16 . Flux-cored wire according to  claim 12 , characterized in that less than 1% of the filling elements that it contains are damaged during welding of said tube.  
     
     
         17 . Flux-cored wire according to  claim 12 , characterized in that less than 0.6% of the filling elements that it contains are damaged during the welding of said tube.  
     
     
         18 . Flux-cored wire according to  claim 12 , characterized in that it comprises a steel sheath and/or it contains rutile as filling element.  
     
     
         19 . Process according to  claim 2 , characterized in that, in step e) the tube undergoes an axial rotation through an angle between 60° and 105° to the vertical.  
     
     
         20 . Process according to  claim 2 , characterized in that, in step e), the tube undergoes an axial rotation through an angle between 80° and 100° to the vertical.