Roller offset forming tool and method of mitigating distortion in a metal sheet

Abstract

A roller offset forming tool includes a first roller configured to rotate in a first direction against a metal sheet. The first roller includes a first bead having a first shape. The tool includes a second roller disposed opposite and configured to engage with the first roller. The second roller is configured to rotate in a second direction that is opposite to the first direction against the metal sheet to thereby deform the metal sheet and form an offset feature therein. The second roller includes a secondary bead having a second geometry. The first bead is configured to align and mate with the secondary bead thereby hold the metal sheet between the first and second rollers. The first shape and the second geometry are configured to mitigate a distortion of the metal sheet in an area apart from the offset feature and stiffen the metal sheet at the offset feature.

What is claimed is: 
     
         1 . A roller offset forming tool comprising:
 a first roller configured to rotate in a first direction about a first longitudinal axis against a metal sheet;   wherein the first roller includes a first bead having a first shape; and   a second roller disposed opposite and configured to engage with the first roller;   wherein the second roller is configured to rotate in a second direction that is opposite to the first direction about a second longitudinal axis against the metal sheet to thereby deform the metal sheet and form an offset feature therein;   wherein the second roller includes a secondary bead having a second geometry;   wherein the first bead is configured to align and mate with the secondary bead along a first vertical axis that is substantially perpendicular to the first longitudinal axis and the second longitudinal axis to thereby hold the metal sheet between the first roller and the second roller;   wherein the first shape and the second geometry are configured to mitigate a distortion of the metal sheet in an area apart from the offset feature and stiffen the metal sheet at the offset feature.   
     
     
         2 . The roller offset forming tool of  claim 1 , wherein:
 the first bead defines a first channel therein; and   the secondary bead is configured to protrude into the first channel along the first vertical axis.   
     
     
         3 . The roller offset forming tool of  claim 1 , wherein each of the first bead and the secondary bead is symmetrical across the first vertical axis. 
     
     
         4 . The roller offset forming tool of  claim 1 , wherein the first bead is symmetrical across the first vertical axis and the secondary bead is asymmetrical across the first vertical axis. 
     
     
         5 . The roller offset forming tool of  claim 1 , wherein:
 the first roller further includes a primary bead spaced apart from the first bead along the first longitudinal axis and having a first geometry; and   the second roller further includes a second bead spaced apart from the secondary bead along the second longitudinal axis and having a second shape;   wherein the first geometry and the second geometry are configured to mitigate a distortion of the metal sheet in an area apart from the offset feature and stiffen the metal sheet at the offset feature.   
     
     
         6 . The roller offset forming tool of  claim 5 , wherein the second bead is configured to align and mate with the primary bead along a second vertical axis spaced apart from the first vertical axis along the second longitudinal axis to thereby hold the metal sheet between the first roller and the second roller. 
     
     
         7 . The roller offset forming tool of  claim 5 , wherein:
 the second bead defines a second channel therein; and   the primary bead is configured to protrude into the second channel.   
     
     
         8 . The roller offset forming tool of  claim 5 , wherein:
 the first bead has a first radius;   the primary bead has a primary radius that is less than the first radius;   the second bead has a second radius; and   the secondary bead has a secondary radius that is less than the second radius.   
     
     
         9 . The roller offset forming tool of  claim 5 , wherein:
 the first roller has a first distal end;   the second roller has a second distal end aligned with the first distal end along a vertical axis that is substantially perpendicular to the first longitudinal axis and the second longitudinal axis;   the primary bead is disposed at a first distance from the first distal end;   the secondary bead is disposed at a second distance from the second distal end; and   the second distance is from 20% of the first distance from the first distal end to 80% of the first distance from the first distal end.   
     
     
         10 . A motor vehicle comprising an article formed by the roller offset forming tool of  claim 1 . 
     
     
         11 . A roller offset forming system comprising a metal sheet sandwiched between and disposed in contact with the first bead and the secondary bead of the roller offset forming tool of  claim 1 . 
     
     
         12 . The roller offset forming system of  claim 11 , wherein the metal sheet is substantially free from distortion in the area spaced apart from the offset feature. 
     
     
         13 . A roller offset forming tool comprising:
 a first roller configured to rotate in a first direction against a metal sheet;   wherein the first roller includes a first bead having a first shape and a primary bead spaced apart from the first bead and having a first geometry; and   a second roller disposed opposite and configured to engage with the first roller;   wherein the second roller is configured to rotate in a second direction that is opposite to the first direction against the metal sheet to thereby deform the metal sheet and form an offset feature therein;   wherein the second roller includes a second bead having a second shape and a secondary bead spaced apart from the second bead and having a second geometry;   wherein the first shape, the second shape, the first geometry, and the second geometry are configured to mitigate a distortion of the metal sheet in an area apart from the offset feature and stiffen the metal sheet at the offset feature;   wherein each of the first shape and the second geometry incudes a bottom fillet, a top fillet spaced apart from the bottom fillet, a top, a bottom spaced apart from the top, a side wall connecting the top and the bottom, and an angle of inclination defined between the bottom and the side wall; and   wherein each of the first shape and the second geometry is defined by at least one of:
 a first variable set including a bottom fillet radius, a top fillet radius, a bottom half width, a top half width, and a bead height; and 
 a second variable set including the bottom fillet radius, the top fillet radius, the angle of inclination, a side wall length, and the top half width. 
   
     
     
         14 . The roller offset forming tool of  claim 13 , wherein the first shape is dependent upon the second geometry. 
     
     
         15 . The roller offset forming tool of  claim 13 , wherein the first shape is independent of the second geometry. 
     
     
         16 . The roller offset forming tool of  claim 13 , wherein the angle of inclination is greater than 0° and less than or equal to 90°. 
     
     
         17 . A method of mitigating a distortion of a workpiece, the method comprising:
 forming the workpiece having an offset feature and a plurality of areas each spaced apart from the offset feature from a metal sheet with a roller offset forming tool, wherein the roller offset forming tool includes:
 a first roller configured to rotate in a first direction about a first longitudinal axis against a metal sheet; 
 wherein the first roller includes a first bead having a first shape; and 
 a second roller disposed opposite and configured to engage with the first roller; 
 wherein the second roller is configured to rotate in a second direction that is opposite to the first direction about a second longitudinal axis against the metal sheet to thereby deform the metal sheet and form an offset feature therein; 
 wherein the second roller includes a secondary bead having a second geometry; 
 wherein the first bead is configured to align and mate with the secondary bead along a first vertical axis that is substantially perpendicular to the first longitudinal axis and the second longitudinal axis to thereby hold the metal sheet between the first roller and the second roller; 
 wherein the first shape and the second geometry are configured to mitigate a distortion of the metal sheet in an area apart from the offset feature and stiffen the metal sheet at the offset feature; 
   measuring a height (h o ) of the offset feature and an actual height (h i ) of each of the plurality of areas;   assigning a distortion degree value (DDV) to the workpiece;   determining whether the distortion degree value (DDV) is less than or equal to a threshold distortion degree value (DDV t );   if the distortion degree value (DDV) is greater than the threshold distortion degree value (DDV t ), changing at least one of the first shape and the second geometry and forming a subsequent workpiece; and   if the distortion degree value (DDV) is less than or equal to the threshold distortion degree value (DDV t ), forming the subsequent workpiece without changing at least one of the first shape and the second geometry to thereby mitigate the distortion of the workpiece.   
     
     
         18 . The method of  claim 17 , wherein assigning includes calculating the distortion degree value according (DDV) to formula (I):
   DDV=root mean square( h   i   −h )  (I)
   wherein:
 h i  is the actual height of one of the plurality of areas; and 
 h is an ideal height of any distortion and is less than the height (h o ) of the offset feature such that as (h i −h) approaches zero, the distortion of the workpiece is mitigated. 
   
     
     
         19 . The method of  claim 17 , wherein forming includes sandwiching the metal sheet between the first bead and the secondary bead. 
     
     
         20 . The method of  claim 19 , wherein forming includes turning the first roller in the first direction against the metal sheet and turning the second roller in the second direction against the metal sheet such that the primary bead deforms the metal sheet at the secondary bead and thereby forms the offset feature.