Stamping apparatus, method of stamping and stamping mold

Abstract

A method of stamping for separating a workpiece part of sheet metal to obtain a workpiece, the method including a work-hardening step of generating work-hardening at vicinity of outline of the workpiece part of the sheet metal by moving a work-hardening punch having an end side facing the sheet metal toward the sheet metal and locally pressing the vicinity of the outline along the outline with a work-hardening projection provided on the end side of the work-hardening punch, and a separation step of punching the workpiece part of the sheet metal which has finished the work-hardening step with a separation punch and thereby separating the workpiece part from the sheet metal, wherein the work-hardening projection is formed to have V-shaped cross-section with both inner wall and outer wall of the work-hardening projection being inclined to pressing direction of the work-hardening punch.

1 . A stamping apparatus for separating a workpiece part of sheet metal to obtain a workpiece, the stamping apparatus comprising:
 a work-hardening punch having an end side configured to face the sheet metal, the end side provided with a work-hardening projection, wherein the work-hardening projection is configured to generate work-hardening at vicinity of outline of the workpiece part of the sheet metal by locally pressing the vicinity of the outline along the outline;   a work-hardening die provided in pair with the work-hardening punch, wherein the work-hardening die is configured to support the sheet metal on outside of the workpiece part;   a separation punch configured to punch the workpiece part of the sheet metal which has pressed by the work-hardening punch, and thereby separate the workpiece part from the sheet metal; and   a separation die provided in pair with the separation punch, wherein the separation die is configured to support the sheet metal on outside of the workpiece part,   wherein the work-hardening projection is formed to have V-shaped cross-section with both inner wall and outer wall of the work-hardening projection being inclined to pressing direction of the work-hardening punch.   
     
     
         2 . The stamping apparatus of  claim 1 , wherein
 the work-hardening projection is provided successively on the end side of the work-hardening punch, and is configured to follow the outline of the workpiece part of the sheet metal.   
     
     
         3 . The stamping apparatus of  claim 1 , wherein
 ridgeline distance of the work-hardening projection and inner width of the work-hardening die are both configured to be substantially equal to outer width of the workpiece,   outer width of the separation punch is configured to be smaller than outer width of the workpiece, and   inner width of the separation die is configured to be larger than outer width of the workpiece.   
     
     
         4 . The stamping apparatus of  claim 1 , further comprising:
 a counter-punch placed inside a die opening of the work-hardening die, wherein the counter-punch is configured to pressure hold the workpiece part from the opposite side of the work-hardening punch when the sheet metal is pressed by the work-hardening punch.   
     
     
         5 . The stamping apparatus of  claim 1 , further comprising:
 means for transferring the sheet metal that has pressed by the work-hardening punch from the work-hardening die to the separation die.   
     
     
         6 . A method of stamping for separating a workpiece part of sheet metal to obtain a workpiece, the method comprising:
 a work-hardening step of generating work-hardening at vicinity of outline of the workpiece part of the sheet metal by moving a work-hardening punch having an end side facing the sheet metal toward the sheet metal and locally pressing the vicinity of the outline along the outline with a work-hardening projection provided on the end side of the work-hardening punch; and   a separation step of punching the workpiece part of the sheet metal which has finished the work-hardening step with a separation punch and thereby separating the workpiece part from the sheet metal,   wherein the work-hardening projection is formed to have V-shaped cross-section with both inner wall and outer wall of the work-hardening projection being inclined to pressing direction of the work-hardening punch.   
     
     
         7 . A stamping mold for separating a workpiece part of sheet metal to obtain a workpiece, the stamping mold comprising:
 a work-hardening punch having an end side configured to face the sheet metal, the end side provided with a work-hardening projection, wherein the work-hardening projection is configured to generate work-hardening at vicinity of outline of the workpiece part of the sheet metal by locally pressing the vicinity of the outline along the outline;   a work-hardening die provided in pair with the work-hardening punch, wherein the work-hardening die is configured to support the sheet metal on outside of the workpiece part;   a separation punch configured to punch the workpiece part of the sheet metal which has pressed by the work-hardening punch, and thereby separate the workpiece part from the sheet metal; and   a separation die provided in pair with the separation punch, wherein the separation die is configured to support the sheet metal on outside of the workpiece part,   wherein the work-hardening projection is formed to have V-shaped cross-section with both inner wall and outer wall of the work-hardening projection being inclined to pressing direction of the work-hardening punch.