Sheet of Material with Fluid-Resistant Bend Controlling Displacements and Method of Forming the Same

Abstract

A method of preparing a two-dimensional sheet of material for bending along a bend line to form a three-dimensional article having a fluid-resistant bend includes the steps of forming at least one bend-controlling displacement in the thickness direction of the sheet of material, a portion of a periphery of the bend-controlling displacement proximate the bend line defining a sheared face directed toward an opposed sheet surface in the sheet of material on an opposite side of the bend line, and bending the sheet of material. A balancing of the forces during bending produces face-to-surface engagement between the sheared face and the opposed sheet surface such that the sheet material is substantially fluid-resistant along the bend line.

1 . A method of preparing a two-dimensional sheet of material for bending along a bend line to form a three-dimensional article having a fluid-resistant bend, the method comprising:
 forming at least one bend-controlling displacement in the thickness direction of the sheet of material, a portion of a periphery of the bend-controlling displacement proximate the bend line defining a sheared face directed toward an opposed sheet surface in the sheet of material on an opposite side of the bend line; and   bending the sheet of material whereby a balancing of the forces during bending produces face-to-surface engagement between the sheared face and the opposed sheet surface such that the sheet material is substantially fluid-resistant along the bend line.   
     
     
         2 . A method according to  claim 1 , wherein the forming step includes forming a plurality of bend-controlling displacements having a pair of bending straps in the sheet of material intersecting the bend line and a respective sheared face extending therebetween, and wherein the bending step subjects the straps to tension such that the sheared face closely abuts against the opposed sheet surface when the sheet of material is bent. 
     
     
         3 . A method according to  claim 2 , wherein the plurality of bend-controlling displacements are formed in the sheet of material with a sheared edge extending along a respective sheared face along one side of the bend line, and wherein the forming step defines an opposed face opposite each sheared face such that bending produces edge-to-face engagement of the sheet of material during the bending step. 
     
     
         4 . A method according to  claim 1 , wherein the bending step seals the opposed surface to the sheared face when the sheet of material is bent. 
     
     
         5 . A method according to  claim 4 , wherein the seal is substantially formed by close abutment of the sheared face to the opposed surface. 
     
     
         6 . A method according to  claim 5 , wherein abutment is substantially uniform along the sheared face. 
     
     
         7 . A method according to  claim 5 , wherein the seal is formed with substantially no use of sealing materials. 
     
     
         8 . A method according to  claim 4 , further including after the forming step, adhering a layer of coating material to the sheet of material across the bend-controlling displacements. 
     
     
         9 . A method according to  claim 8 , wherein the adhering step provides a continuous layer of flexible coating material to the sheet of material across the plurality of bend-controlling displacements, which continuous layer remains substantially intact after the bending step. 
     
     
         10 . A method according to  claim 9 , wherein the coating material is paint. 
     
     
         11 . A method according to  claim 4 , further including after the bending step, adhering a layer of coating material to the sheet of material across the bend-controlling displacements. 
     
     
         12 . A method according to  claim 1 , wherein the forming step forms the bend-controlling displacement with a substantially oval-shape and includes a periphery with end portions and a crown portion extending between the end portions. 
     
     
         13 . A method according to  claim 12 , wherein the forming step provides the crown portion of the bend-controlling displacement with an arcuate profile. 
     
     
         14 . A method according to  claim 12 , wherein the crown portion is a large radii arc. 
     
     
         15 . A method according to  claim 12 , wherein the end portions are a small radii arc. 
     
     
         16 . A method according to  claim 12 , the bend-controlling displacement further including transition zones between the crown portion and the end portions. 
     
     
         17 . A method according to  claim 16 , wherein the transition zones have a radius of curvature intermediate the radii of curvature of the end portions and the crown portion. 
     
     
         18 . A method according to  claim 16 , wherein the first order derivative of the radius of curvature of the sheared face along the crown portion, the transition zones and the end portions is substantially uniform. 
     
     
         19 . A method according to  claim 1 , wherein the forming step forms a joggle zone connecting an unsheared portion of the bend-controlling displacement to the sheet material, wherein each end portion includes a portion of the sheared face and a portion of the joggle zone. 
     
     
         20 . A method according to  claim 1 , wherein the sheared edge extends below the opposed sheet surface a distance that is at least 75% the thickness of the material. 
     
     
         21 . A method according to  claim 1 , wherein the sheared edge has a z-depth of between 0.095-0.110 mm. 
     
     
         22 . A method according to  claim 1 , wherein the sheet of material is steel. 
     
     
         23 . A method according to  claim 1 , wherein the sheared face extends to within approximately 40° of a longitudinal axis of the displacement with respect to a radial center of the end portion. 
     
     
         24 . A method according to  claim 1 , wherein the forming is accomplished using one of a stamping process, punching process, a roll forming process, or an embossing process. 
     
     
         25 . A method according to  claim 1 , wherein the three-dimensional article is a NEMA-3 pull box. 
     
     
         26 . A method according to  claim 13 ,
 wherein the curved crown portion is dimensioned to produce the face-to-surface engagement between the sheared face and the opposed sheet surface.   
     
     
         27 . A method according to  claim 26 , wherein the end portions have a smaller radius of curvature than the crown portions. 
     
     
         28 .- 35 . (canceled) 
     
     
         36 . A two-dimensional sheet of material formed for bending along a bend line to form a three-dimensional article having a fluid-resistant bend, the sheet of material comprising:
 a sheet of material including a bend-controlling displacement in the thickness direction of the sheet of material, a portion of a periphery of the bend-controlling displacement proximate the bend line defining a sheared face directed toward an opposed sheet surface in the sheet of material on an opposite side of the bend line, the sheared face and opposed sheet surface configured and positioned to produce face-to-surface engagement of the sheet of material after bending such the bend is substantially fluid-resistant when bent.   
     
     
         37 .- 50 . (canceled) 
     
     
         51 . A rigid three-dimensional article formed by the method according to  claim 1 . 
     
     
         52 . A rigid three-dimensional article including a sheet of material according to  claim 36 .