Ironing punch

Abstract

In an ironing punch to be used for metal ironing, a dot-shaped recess is distributed on an outer peripheral surface of the ironing punch, and a raised portion is formed on at least part of a peripheral edge portion of the dot-shaped recess.

1 . An ironing punch to be used for metal ironing, wherein
 a dot-shaped recess is distributed on an outer peripheral surface of the ironing punch, and   a raised portion is formed on at least part of a peripheral edge portion of the dot-shaped recess.   
     
     
         2 . The ironing punch according to  claim 1 , wherein the raised portion is formed over an entire periphery of the peripheral edge portion of the dot-shaped recess. 
     
     
         3 . The ironing punch according to  claim 1 , wherein the raised portion is formed on part of the peripheral edge portion of the dot-shaped recess. 
     
     
         4 . The ironing punch according to  claim 3 , wherein the raised portion is formed on part of the peripheral edge portion of the dot-shaped recess on a side opposite to a punch tip side. 
     
     
         5 . The ironing punch according to  claim 4 , wherein when viewed in a cross section along an axial direction of the ironing punch, the dot-shaped recess has a shape having a deepest portion disproportionately located on the side opposite to the punch tip side. 
     
     
         6 . The ironing punch according to  claim 5 , wherein an eccentricity ratio of the deepest portion ranges from 30 to 100%. 
     
     
         7 . An ironing method, comprising:
 inserting an ironing punch described in  claim 1  into a metal cylinder;   performing ironing by passing the metal cylinder through an annular die; and   thinning the metal cylinder by pulling out the punch after the ironing is completed.   
     
     
         8 . The ironing method according to  claim 7 , wherein the metal cylinder comprises an organic resin layer on an inner surface of the metal cylinder. 
     
     
         9 . The ironing method according to  claim 8 , wherein the organic resin layer is formed of a thermoplastic resin. 
     
     
         10 . An ironing can, comprising:
 a body portion having a hollow cylinder; and   a bottom portion closing a lower end of the body portion, wherein   a dot-shaped protrusion is distributed on an inner peripheral surface of the body portion, and   an apex of the dot-shaped protrusion is disproportionately located in a direction opposite to a bottom portion when viewed in a longitudinal section along an axial direction.   
     
     
         11 . The ironing can according to  claim 10 , wherein
 an organic resin layer is laminated on the inner peripheral surface of the body portion, and   the dot-shaped protrusion is distributed on a surface of the organic resin layer.