Method of forming a weld notch in a sheet metal piece

Abstract

Sheet metal pieces intended to be welded can be made with weld notches located along one or more edges. A weld notch is characterized by the absence of certain material constituents so that they do not unacceptably contaminate nearby welds. The weld notch can be created by first forming an ablation trench along the sheet metal piece, then separating the sheet metal piece along the formed ablation trench into two separate pieces, at least one of which includes a newly formed and weldable edge.

1 . A method of forming a weld notch in a sheet metal piece, comprising the steps of:
 (a) providing a sheet metal piece having a plurality of material layers;   (b) forming an ablation trench along the sheet metal piece by removing at least a portion of the plurality of material layers along an ablation path so that the ablation trench is spaced away from an edge of the sheet metal piece; and   (c) cutting the sheet metal piece along the ablation trench to form the weld notch.   
     
     
         2 . The method of  claim 1 , wherein step (b) further comprises forming the ablation trench within an edge region of the sheet metal piece, and step (c) further comprises removing a portion of the edge region. 
     
     
         3 . The method of  claim 1 , wherein step (b) further comprises forming the ablation trench away from an edge region of the sheet metal piece, and step (c) further comprises cutting the sheet metal piece into two separate sheet metal pieces. 
     
     
         4 . The method of  claim 1 , wherein step (b) further comprises directing first and second laser beams toward the sheet metal piece so that the beams overlap at a composite laser spot and form the ablation trench with a non-uniform depth. 
     
     
         5 . The method of  claim 4 , wherein step (c) further comprises cutting the sheet metal piece along a trim line that corresponds to the portion of the ablation trench formed by the composite laser spot. 
     
     
         6 . The method of  claim 1 , wherein step (b) further comprises directing a laser beam toward the sheet metal piece at a non-zero or offset angle of incidence (a) in order to form a weld notch that is offset with respect to the plurality of material layers. 
     
     
         7 . A method of forming a weld notch in a sheet metal piece, comprising the steps of:
 (a) providing a sheet metal piece having a plurality of material layers;   (b) forming an ablation trench along the sheet metal piece by removing at least a portion of the plurality of material layers along an ablation path, wherein the ablation trench is defined in part by surfaces that oppose each other across the width of the ablation trench; and   (c) removing a portion of the sheet metal piece that includes one of the opposing surfaces formed in step (b) to form the weld notch, wherein the weld notch is partly defined by the other of the opposing surfaces.   
     
     
         8 . The method of  claim 7 , wherein the ablation trench is further defined in part by a third surface extending between the opposing surfaces, and step (c) further comprises cutting the sheet metal piece along a central region of the ablation trench so that the weld notch is further defined by a portion of the third surface and another portion of the third surface is removed in step (c). 
     
     
         9 . The method of  claim 7 , wherein the ablation trench is further defined in part by a third surface extending between the opposing surfaces, and step (c) comprises cutting the sheet metal piece along one of the opposing surfaces so that the weld notch is further defined by substantially the entire third surface. 
     
     
         10 . The method of  claim 7 , wherein step (b) further comprises directing first and second laser beams toward the sheet metal piece so that the beams overlap at a composite laser spot and form the ablation trench with a non-uniform depth. 
     
     
         11 . The method of  claim 10 , wherein step (c) further comprises cutting the sheet metal piece along a trim line that corresponds to the portion of the ablation trench formed by the composite laser spot. 
     
     
         12 . The method of  claim 7 , wherein step (b) further comprises directing a laser beam toward the sheet metal piece at a non-zero or offset angle of incidence (a) in order to form a weld notch that is offset with respect to the plurality of material layers. 
     
     
         13 . A method of forming a weld notch in a sheet metal piece, comprising the steps of:
 (a) providing a sheet metal piece having opposite first and second sides and a sheared edge extending therebetween, wherein material from a coating material layer along the first side extends at least partially along the sheared edge toward the second side in a shearing direction;   (b) removing some of the coating material layer from the sheet metal piece along a pre-determined trim line location; and   (c) separating the sheet metal piece into first and second pieces along the trim line location, wherein the first piece includes a newly formed weldable edge substantially free of material from the coating material layer and the second piece includes the sheared edge.   
     
     
         14 . The method of  claim 13 , wherein step (b) comprises forming an ablation trench along the trim line location, the ablation trench having a plurality of trench surfaces, at least a portion of some of the trench surfaces remain with the first sheet metal piece of step (c) as weld notch surfaces. 
     
     
         15 . The method of  claim 13 , wherein the pre-determined trim line location is located within an edge region of the sheet metal piece so that the second piece is not usable to form a welded blank assembly. 
     
     
         16 . The method of  claim 13 , wherein the pre-determined trim line is located away from edge regions of the sheet metal piece so that each of the first and second pieces includes a weld notch along a newly formed weldable edge substantially free of material from the coating material layer and is usable to form a welded blank assembly. 
     
     
         17 . The method of  claim 13 , wherein step (b) further comprises directing first and second laser beams toward the sheet metal piece so that the beams overlap at a composite laser spot and forms an ablation trench with a non-uniform depth. 
     
     
         18 . The method of  claim 17 , wherein the trim line location corresponds to the portion of the ablation trench formed by the composite laser spot and step (c) further comprises cutting the sheet metal piece along the trim line location. 
     
     
         19 . The method of  claim 13  wherein step (b) further comprises directing a laser beam toward the sheet metal piece at a non-zero or offset angle of incidence (a) in order to form a weld notch that is offset with respect to the coating material layer.