Thermal-assisted multiple sheet roll forming

Abstract

A thermal-assisted method deforms a sheet metal assembly having constrained ends. A focus bending area located between the constrained ends is heated. The focus bending area is bent while the sheet metal assembly is within an elevated bending temperature range. A sheet metal assembly may be formed by this method, which includes an outer metal sheet and an inner metal sheet fixed together to form constrained ends. The sheet metal assembly has a bend formed therein between the first and second constrained ends, wherein each metal sheet is bent at the bend with a maximum gap between the inner and outer metal sheets at the bend. The maximum gap is no greater than five times the thickness of one of the inner and outer metal sheets, and the bend has a radius less than three times the thickness of one of the inner and outer sheets.

What is claimed is: 
     
         1 . A method of forming a sheet metal assembly, the method comprising:
 providing a sheet metal assembly, the sheet metal assembly including at least an outer metal sheet and an inner metal sheet, the outer and inner metal sheets being fixed together to form a constrained first end and a constrained second end, the sheet metal assembly having an initial temperature;   heating a focus bending area of the sheet metal assembly to at least a bending temperature range that is greater than the initial temperature, the focus bending area being located between the constrained first and second ends of the sheet metal assembly; and   bending the focus bending area of the sheet metal assembly while the sheet metal assembly is within the bending temperature range.   
     
     
         2 . The method of  claim 1 , wherein the step of bending includes rolling a roller tool against the sheet metal assembly to form a bend in the focus bending area, the bend having an outer side and an inner side. 
     
     
         3 . The method of  claim 2 , further comprising disposing a heat source adjacent to the outer sheet at the focus bending area prior to performing the heating step, and heating the focus bending area via the heat source. 
     
     
         4 . The method of  claim 1 , wherein the step of heating includes applying a laser beam to the focus bending area. 
     
     
         5 . The method of  claim 1 , further comprising:
 providing the inner metal sheet as being formed of a first material; and   providing the outer metal sheet as being formed of a second material, the first and second materials being different from one another.   
     
     
         6 . The method of  claim 1 , further comprising:
 providing one of the inner and outer metal sheets as being formed of an aluminum alloy; and   providing the other of the inner and outer metal sheets as being formed of steel.   
     
     
         7 . The method of  claim 1 , further comprising:
 providing the inner metal sheet having a first thickness; and   providing the outer metal sheet having a second thickness, the first and second thicknesses being unequal.   
     
     
         8 . The method of  claim 1 , wherein the step of bending comprises forming a bend at the focus bending area, the method further comprising maintaining a maximum gap between the inner and outer metal sheets at the bend, the maximum gap being no greater than five times the thickness of one of the inner and outer metal sheets. 
     
     
         9 . The method of  claim 8 , wherein the maximum gap is no greater than half the thickness of one of the inner and outer metal sheets. 
     
     
         10 . The method of  claim 1 , further comprising quenching the sheet metal assembly rapidly after bending to retain a high-temperature phase structure at room temperature. 
     
     
         11 . The method of  claim 1 , wherein the step of bending comprises forming a bend at the focus bending area, the bend having a radius less than three times the thickness of one of the inner and outer metal sheets. 
     
     
         12 . The method of  claim 1 , further comprising providing the inner and outer metal sheets having substantially equal thicknesses. 
     
     
         13 . The method of  claim 2 , further comprising providing a die having a die bend formed therein, wherein the step of bending includes rolling the sheet metal assembly against the die bend with the roller tool to form a part bend in the sheet metal assembly. 
     
     
         14 . A sheet metal assembly comprising:
 an outer metal sheet; and   an inner metal sheet, the outer and inner metal sheets being fixed together to form a constrained first end and a constrained second end, the sheet metal assembly having a bend formed therein between the first and second constrained ends, wherein each metal sheet is bent at the bend with a maximum gap between the inner and outer metal sheets at the bend, the maximum gap being no greater than five times the thickness of one of the inner and outer metal sheets, the bend having a radius less than three times the thickness of one of the inner and outer metal sheets.   
     
     
         15 . The sheet metal assembly of  claim 14 , the inner metal sheet being formed of a first material, and the outer metal sheet being formed of a second material, the first and second materials being different from one another. 
     
     
         16 . The sheet metal assembly of  claim 15 , one of the inner and outer metal sheets being formed of an aluminum alloy, and the other of the inner and outer metal sheets being formed of steel. 
     
     
         17 . The sheet metal assembly of  claim 14 , the inner metal sheet having a first thickness, and the outer metal sheet having a second thickness, the first and second thicknesses being unequal. 
     
     
         18 . The sheet metal assembly of  claim 14 , wherein the maximum gap is no greater than half the thickness of one of the inner and outer metal sheets. 
     
     
         19 . The sheet metal assembly of  claim 14 , at least one of the inner and outer metal sheets retaining a high-temperature phase structure at room temperature. 
     
     
         20 . The sheet metal assembly of  claim 14 , the inner and outer metal sheets having substantially equal thicknesses.