Method and Apparatus for Sharp Bending High Strength Panels

Abstract

A method and apparatus for forming a flange on a panel. The flange is formed under compression to provide a reduced outside radius on the finished flange. The flange may be formed about an outside corner with a distal edge of the flange being restricted by a limiting edge formed on a die. Alternatively, the flange may be formed into an inside corner of a die with a compressive force being exerted on a distal edge of the flange by a compressing tool while a forming tool forms the flange with a reduced final outside radius.

What is claimed is: 
     
         1 . A method of forming a sharp bend on a panel comprising:
 pre-bending the panel to form a flange having a radius at a base portion of the flange between the flange and a body portion of the panel;   clamping the flange between a distal end of the flange and the base portion with a clearance being defined between the flange and an anvil surface; and   compressing the flange against the anvil surface.   
     
     
         2 . The method of  claim 1  further comprising clamping the body portion of the panel between a clamping pad and a die while a punch is reciprocally moved to perform the pre-bending step and then performs the compressing step. 
     
     
         3 . The method of  claim 2  wherein the die has a limiting edge that is engaged by the distal end of the flange during the compressing step. 
     
     
         4 . The method of  claim 3  wherein the flange is formed into engagement with the anvil surface of the die by the punch, and wherein the distal end of the flange slides along the anvil surface until the distal end engages the limiting edge. 
     
     
         5 . The method of  claim 1  wherein the clearance defined between the flange and an anvil surface is defined by an arc-shaped portion of the flange adjacent to the base portion of the flange and wherein the method further comprises compressing the arc-shaped portion against the anvil surface causing the arch-shaped portion to flow toward the base portion of the flange. 
     
     
         6 . The method of  claim 1  further comprising:
 clamping the body portion of the panel between a clamping pad and a die; 
 compressing the distal end of the flange between a compressing tool and the die; and 
 forming the base portion of the flange into a corner of the die with a forming tool while the flange is compressed by the compressing tool. 
 
     
     
         7 . The method of  claim 6  wherein the clearance is defined between the flange and the corner of the die and is defined by an arc-shaped portion of the flange at the base portion of the flange, and wherein the method further comprises causing the base portion of the flange to flow into the corner of the die. 
     
     
         8 . A tool for forming a flange on a panel comprising:
 a die having a limiting edge engaging a distal end of the flange;   a clamping pad for clamping the panel against the die; and   a punch initially engages the panel to form the flange with a radius at a base portion of the flange, and wherein the punch forms the flange against an anvil surface of the die while the flange is compressed between the clamping pad and the limiting edge to reduce the radius of the flange.   
     
     
         9 . The tool of  claim 8  further comprising:
 an outside corner provided on the die, wherein the punch engages the panel to initially form the flange around the outside corner, and wherein the clamping pad clamps the panel on one side of the outside corner. 
 
     
     
         10 . The tool of  claim 8  wherein the base portion of the flange has an arc-shaped portion that defines an arc-shaped clearance relative to the anvil surface, and wherein the punch forms the arc-shaped portion of the flange into the base portion of the flange. 
     
     
         11 . A tool for forming a flange on a panel comprising:
 a die having an inside corner that receives a base portion of the flange in a spaced relationship, wherein the base portion of the flange has an initial radius;   a clamping pad for clamping the panel against the die;   a compressing tool engaging a distal edge of the flange; and   a forming tool that forms the base portion of the flange into the inside corner while the flange is compressed by the compressing tool to form a final radius that is smaller than the initial radius.   
     
     
         12 . The tool of  claim 11  wherein the inside corner has a radius that corresponds to a final outside radius of the flange, and wherein the forming tool has a radius that corresponds to a final inside radius of the forming tool. 
     
     
         13 . The tool of  claim 11  wherein the compressing tool moves with the forming tool to compress the flange while the forming tool forms the final radius. 
     
     
         14 . The tool of  claim 11  wherein the flange is pre-formed in a forming die to a radius that is greater than a minimum radius at which a fracture may occur from bending the flange.