Method and system for metal drawing and redrawing

Abstract

A system and method of forming a drawn cup for production of a metal container is provided. The system and method contemplates the provision of gap pins to control the relative movements of cup forming features and provide for reduced risk of damage including pinching, chatter, slivering, and thinning of portions of the cup.

What is claimed is: 
     
         1 . A method of forming a drawn metallic cup having a sidewall, and a dome comprising:
 providing a sheet of stock metal material;   forming a plurality of through holes in the sheet, the through holes provided for receiving gap pins of a forming tool;   providing a forming tool, the forming tool comprising:
 i. a draw die; 
 ii. a draw pad; 
 iii. a blank and draw die; 
 iv. a center punch; and 
 v. a plurality of gap pins; 
   providing said gap pins through said through holes such that distal ends of said gap pins are provided proximal a flange portion of said draw pad;   wherein the stock material to be formed is provided between said draw pad and said blank and draw die;   sheering the sheet to form a generally circular blank;   forming the generally circular blank into a first shape by moving the draw die in a first direction, wherein a portion of the generally circular blank conforms to the draw die under pressure, and wherein the generally circular blank is transitioned out of a space between the draw pad and the blank and draw die;   contacting said flange portion of said draw pad with the distal ends of the gap pins;   contacting an upper surface of the stock material with the center punch travelling in a second direction which is substantially an opposite direction as the first direction to form the blank in a second shape.   
     
     
         2 . The method of  claim 1 , wherein the forming tool further comprises a blanking die. 
     
     
         3 . The method of  claim 2 , wherein the blanking die comprises a cutting edge for sheering the sheet. 
     
     
         4 . The method of  claim 2 , wherein the gap pins extend through apertures in said blanking die. 
     
     
         5 . The method of  claim 1 , wherein prior to forming the generally circular blank into the first shape, a gap between said draw pad and said blank and draw die is approximately equal to a gauge of said sheet of stock material. 
     
     
         6 . The method of  claim 1 , wherein after forming the generally circular blank into the first shape, a gap between said draw pad and said blank and draw die is less than a gauge of said sheet of stock material. 
     
     
         7 . The method of  claim 1 , further comprising indexing said sheet of stock material and performing further drawing and redrawing operations. 
     
     
         8 . A method of forming a drawn and redrawn container body, the method comprising:
 providing a sheet of stock material comprising a plurality of preformed holes for receiving gap pins and positioning said sheet;   providing a forming tool, the forming tool comprising:   a draw die;   a draw pad;   a blank and draw die;   a center punch; and   a plurality of gap pins;   providing said gap pins through said preformed holes, such that said center punch and said draw die are aligned substantially coaxially with a blank to be formed;   wherein said blank to be formed is provided between said draw pad and said blank and draw die, and a gap between said draw pad and said blank and draw die is approximately equal to a gauge of said sheet;   sheering the sheet to form a generally circular blank;   forming the generally circular blank into a first shape by moving the draw die in a first direction, wherein a portion of the generally circular blank conforms to the draw die under pressure, and wherein the first shape is withdrawn from a space between the draw pad and the blank and draw die;   wherein an upward movement of the draw pad is limited by the gap pins wherein distal ends of the gap pins contact a flange portion of the draw pad; and   contacting an upper surface of the stock material with the center punch in a substantially opposite direction as the first direction to create a second shape comprising a cup.   
     
     
         9 . The method of  claim 8 , wherein the forming tool further comprises a blanking die. 
     
     
         10 . The method of  claim 9 , wherein the blanking die comprises a cutting edge for sheering the sheet. 
     
     
         11 . The method of  claim 9 , wherein the gap pins extend through apertures in said blanking die. 
     
     
         12 . The method of  claim 8 , wherein prior to forming the generally circular blank into the first shape, a gap between said draw pad and said blank and draw die is approximately equal to a gauge of said sheet of stock material. 
     
     
         13 . The method of  claim 8 , wherein after forming the generally circular blank into the first shape, a gap between said draw pad and said blank and draw die is less than a gauge of said sheet of stock material. 
     
     
         14 . The method of  claim 8 , wherein the gap pins prevent said draw pad from contacting said blank and draw die. 
     
     
         15 . The method of  claim 8 , further comprising indexing said sheet of stock material and performing further drawing and redrawing operations. 
     
     
         16 . A device for forming and reforming a drawn cup for a metal container body, the device comprising:
 a forming tool comprising a draw die, a draw pad, a blank and draw die, a center punch, a blanking die and a plurality of gap pins;   wherein the draw die is provided substantially coaxial with and movable relative to at least one of the draw pad and the blank and draw die;   wherein the gap pins comprise a first end, a second end and a predetermined length therebetween;   the first ends of the gap pins are secured to the blank and draw die such that the second ends of the gap pins are provided at a fixed distance relative to the blank and draw die; and   wherein a shut height between the draw pad and the blank and draw die is limited by said gap pins.   
     
     
         17 . The device of  claim 16 , further comprising a blanking die, the blanking die comprising a cutting edge adapted for cutting a circular blank of material to be deformed by the device. 
     
     
         18 . The device of  claim 16 , wherein at least one of the draw pad and the blank and draw die comprise an internal void and wherein the draw die is translatable within said internal void. 
     
     
         19 . The device of  claim 16 , wherein an outer circumference of the draw die corresponds to an internal diameter of a cup to be formed. 
     
     
         20 . The device of  claim 16 , wherein the draw die comprises an annular feature adapted to receive the center punch during reforming of a cup.