Method of trimming ultra high strength hot stamping steel sheet using coining

Abstract

The present invention may provide a method of trimming a ultra high strength hot stamping steel sheet using coining, which includes a forming step and a coining step which are simultaneously performed on a hot stamping steel sheet.

What is claimed is: 
     
         1 . A method of trimming a ultra high strength hot stamping steel sheet using coining, the method comprising:
 forming and coining a hot stamping steel sheet.   
     
     
         2 . The method of  claim 1 , wherein a coining bushing, which is used for the coining, is mounted at an end portion of flanges of dies. 
     
     
         3 . The method of  claim 2 , wherein the dies include an upper die and a lower die and coining bushings are mounted on the flanges of the upper die and the lower die which are used for the forming. 
     
     
         4 . The method of  claim 3 , wherein the coining bushings are made of a material identical to a material applied to the upper die and the lower die which are used for the forming. 
     
     
         5 . The method of  claim 3 , wherein the coining bushings are attachable and detachable to the upper die and the lower die respectively. 
     
     
         6 . The method of  claim 3 , wherein when a thickness of the hot stamping steel sheet is greater than 0 mm and equal to or smaller than approximately 1.5 mm, the coining bushings protrude to the outside of the upper die and the lower die at a height of approximately 0.5 mm, respectively. 
     
     
         7 . The method of  claim 3 , wherein when a thickness of the hot stamping steel sheet is greater than approximately 1.5 mm, the coining bushings protrude to the outside of the the upper die and the lower die at a height which is approximately 30% of the thickness of the hot stamping steel sheet. 
     
     
         8 . The method of  claim 1 , wherein after the forming and the coining are simultaneously performed, hard trimming is performed on the hot stamping steel sheet by using a press. 
     
     
         9 . The method of  claim 8 , further comprising:
 before the forming and the coining are simultaneously performed on the hot stamping steel sheet, blanking a steel sheet in a form of a coil, and heating the blank steel sheet.