Method for manufacturing container and apparatus for manufacturing container

Abstract

A method of manufacturing a container made of metal, including a bottom portion and a body portion, being open on an upper face side, and having a shape in which the body portion expands outward toward the upper face side. The method includes a stretch forming step of expanding a diameter of a stepped cup body made of metal by operating a diameter expanding punch having a tapered pressing portion that is smaller in diameter than an inner diameter of the large-diameter cylindrical portion and larger in diameter than an inner diameter of the small-diameter cylindrical portion of the stepped cup body along a cylindrical axis direction from an opening side of the large-diameter cylindrical portion, in which the stretch forming step is performed at least once.

1 . A method for manufacturing a container made of metal, including a bottom portion and a body portion, being open on an upper face side, and having a shape in which the body portion expands outward toward the upper face side, the method comprising:
 (a) expanding a diameter of a stepped cup body made of metal and having a small-diameter cylindrical portion having a bottomed cylindrical shape and a large-diameter cylindrical portion with an opening on an upper face side and contiguous to an upper end of the small-diameter cylindrical portion via a step portion by operating a diameter expanding punch having a tapered pressing portion that is smaller in diameter than an inner diameter of the large-diameter cylindrical portion and larger in diameter than an inner diameter of the small-diameter cylindrical portion of the stepped cup body along a cylindrical axis direction from an opening side of the large-diameter cylindrical portion, wherein   step (a) is performed at least once.   
     
     
         2 . The method for manufacturing a container according to  claim 1 , wherein step (a) is repeated a plurality of times. 
     
     
         3 . The method for manufacturing a container according to  claim 2 , wherein step (a) is repeated from 2 to 10 times. 
     
     
         4 . The method for manufacturing a container according to  claim 1  or  2 , wherein an angle of the step portion of the stepped cup body to a plane perpendicular to an axial direction of the stepped cup body is from 0° to 60°. 
     
     
         5 . The method for manufacturing a container according to  claim 1  or  2 , wherein a diameter of a tapered pressing portion of a diameter expanding punch used in step (a) performed earlier and a diameter of a tapered pressing portion of a diameter expanding punch used in step (a) performed subsequently are different from each other. 
     
     
         6 . The method for manufacturing a container according to  claim 1  or  2 , wherein
 the body portion of the container is formed into a shape in which a line connecting an outer peripheral face at 10% height and an outer peripheral face at 90% height from a lowermost portion expands outward at an angle of from 2° to 15° when a total height of the container is 100%, and 
 when the two containers are stacked, a projecting portion of the container placed above projecting upward has a height of 20 mm or less from an upper end of the container placed below. 
 
     
     
         7 . The method for manufacturing a container according to  claim 6 , wherein
 the bottom portion has a thickness of from 0.20 mm to 0.35 mm,   the body portion has a thickness of from 0.10 to 0.22 mm in a height range of 50±10% when the total height of the container is 100%, and   the body portion is formed into a shape in which the line connecting the outer peripheral face at 10% height and the outer peripheral face at 90% height from the lowermost portion expands outward at an angle of from 3° to 10° when the total height of the container is 100%.   
     
     
         8 . The method for manufacturing a container according to  claim 6 , wherein a ratio of the projecting portion to a height of the container is from 4% to 15%. 
     
     
         9 . The method for manufacturing a container according to  claim 6 , wherein a ratio of the projecting portion to a height of the container is from 5% to 9%. 
     
     
         10 . The method for manufacturing a container according to  claim 6 , wherein the body portion includes a contact portion with a less area configured to avoid close contact with another container when the container is stacked with the other container. 
     
     
         11 . An apparatus for manufacturing a container made of metal, including a bottom portion and a body portion, being open on an upper face side, and having a shape in which the body portion expands outward toward the upper face side, the apparatus comprising:
 at least one stretch forming die, each of the stretch forming die including a diameter expanding punch having a tapered pressing portion that is configured to expand a diameter of a stepped cup body made of metal and having a small-diameter cylindrical portion having a bottomed cylindrical shape and a large-diameter cylindrical portion with an opening on an upper face side and contiguous to an upper end of the small-diameter cylindrical portion via a step portion by pressing along a cylindrical axis direction from an opening side of the large-diameter cylindrical portion and that is smaller in diameter than an inner diameter of the large-diameter cylindrical portion and larger in diameter than an inner diameter of the small-diameter cylindrical portion of the stepped cup body.   
     
     
         12 . The apparatus for manufacturing a container according to  claim 11 , wherein the at least one forming die is a plurality of stretch forming dies. 
     
     
         13 . The apparatus for manufacturing a container according to  claim 12 , wherein the number of the plurality of stretch forming dies is from 2 to 10. 
     
     
         14 . The apparatus for manufacturing a container according to  claim 11  or  12 , wherein an angle of the step portion of the stepped cup body to a plane perpendicular to an axial direction of the stepped cup body is from 0° to 60°. 
     
     
         15 . The apparatus for manufacturing a container according to  claim 11  or  12 , wherein diameters of the tapered pressing portions of the diameter expanding punches included in the plurality of stretch forming dies are different from each other.