Three-piece square can and method of manufacturing the same

Abstract

The present invention provides a three-piece rectangular can which can overcome drawbacks (joint defect) of a can body joint portion of a three-piece can, and is of a new type which overcomes shortage of a can body strength which a two-piece can possesses, and exhibits excellent liquid leakage resistance, excellent can body strength and excellent heat radiation property or the like even when the can is used as a casing of a battery or electric equipment. For this end, the three-piece rectangular can of the present invention is formed such that a circular blank formed of an aluminum plate which forms an organic film on at least one surface thereof is formed into a bottomed circular can by deep drawing such that the organic film forms an inner side of the can, a cylindrical sleeve having no seam on a side surface thereof is formed by cutting a can bottom of the bottomed circular can, a rectangular can body portion having no seam on a side surface thereof is formed by deforming the cylindrical sleeve into a rectangular shape, a necking formed portion is formed by applying necking forming to opening portions at both ends of the rectangular can body, and a top lid and a bottom lid are mounted on the opening portions at both ends of the rectangular can body by double seaming by way of an organic compound.

1 . A three-piece rectangular can in which a necking formed portion is formed by applying necking forming to opening portions at both ends of a rectangular can body portion having no seam on a side surface thereof, and a top lid and a bottom lid are seamed by double seaming to the opening portions at both ends of the rectangular can body portion by way of an organic compound, wherein the three-piece rectangular can is formed of an aluminum plate having an organic film formed on at least one surface thereof, and the organic film is formed on at least inner surfaces of the rectangular can body, the top lid and the bottom lid. 
   
   
       2 . A three-piece rectangular can according to  claim 1 , wherein the rectangular can body portion having no seam on the side surface thereof is formed such that a cylindrical sleeve having no seam on a side surface thereof which is formed by cutting a bottom portion of a bottomed circular can from a circular blank by deep drawing is deformed into a rectangular sleeve and the rectangular sleeve has the opening portions at both ends thereof, and the necking formed portion is formed on the opening portions by applying necking forming to the opening portions. 
   
   
       3 . A three-piece rectangular can according to  claim 1 , wherein the rectangular can body portion having no seam on the side surface thereof is formed such that a cylindrical sleeve having no seam on a side surface thereof which is formed by cutting a bottom portion of a bottomed circular can from a circular blank by deep drawing is deformed into a rectangular sleeve and the rectangular sleeve has the opening portions at both ends thereof, the necking formed portion is formed on the opening portions by applying necking forming to the opening portions and, thereafter, a plurality of beads is formed on the rectangular can body portion in a state that the beads surround the rectangular can body. 
   
   
       4 . A three-piece rectangular can according to  claim 1 , wherein a through hole is formed in center portions of the top lid and the bottom lid which are mounted on the opening portions at both ends of the rectangular can body portion having no seam on the side surface thereof by double seaming, and an electrode is mounted in the through hole by way of an insulator. 
   
   
       5 . A three-piece rectangular can according to  claim 1 , wherein the top lid or the bottom lid of the three-piece rectangular can is formed of an aluminum plate to which a non-stretched polyester film which sets a degree of crystallization thereof within a range from 20% to 40% by preheating treatment before forming is applied. 
   
   
       6 . A three-piece rectangular can according to  claim 1 , wherein the three-piece rectangular can which is used as a battery container and is formed of an aluminum plate which applies a biaxially stretched polyester film to at least the inner surfaces of the rectangular can body portion, the top lid and the bottom lid, and the biaxially stretched polyester film possesses an X-ray diffraction intensity ratio which satisfies 5≧I A /I B ≧1, wherein I A  is an X-ray diffraction intensity on a diffraction plane which is parallel to a surface of the polyester film and has a surface distance of approximately 0.34 nm (a CuKαX-ray diffraction angle being set to a value which falls within a range from 24° to 28°), and I B  is an X-ray diffraction intensity on a diffraction plane which is parallel to the surface of the polyester film and has a surface distance of approximately 0.39 nm (a CuKαX-ray diffraction angle being set to a value which falls within a range from 21.5° to 24°). 
   
   
       7 . A manufacturing method of a three-piece rectangular can being characterized in that a circular blank formed of an aluminum plate which forms an organic film on at least one surface thereof is formed into a bottomed circular can by deep drawing such that the organic film forms an inner side of the can, a cylindrical sleeve having no seam on a side surface thereof is formed by cutting a bottom portion of the bottomed circular can, a rectangular can body portion having no seam on a side surface thereof is formed by deforming the cylindrical sleeve into a rectangular shape, a necking formed portion is formed by applying necking forming to opening portions at both ends of the rectangular can body, and a top lid and a bottom lid are mounted on the opening portions at both ends of the rectangular can body by double seaming by way of an organic compound. 
   
   
       8 . A necking method of a rectangular can being characterized in that, in performing necking forming for squeezing an opening portion of a rectangular can body of a rectangular can, a first core is arranged in the inside of a necking formed portion of the rectangular can, a second split core which is expansible and shrinkable is arranged on a lower portion of the necking formed portion and, thereafter, the necking formed portion is formed using a necking die. 
   
   
       9 . A necking method of a rectangular can according to  claim 8 , wherein the rectangular can body is arranged outside the second core on a bolster, the second core is moved in an expansible manner in a state that the second core supports a lower portion of the necking formed portion and, thereafter, the first core mounted on a slide is lowered toward the second core thus positioning the first core at the necking formed portion, and the necking die is lowered to perform the necking forming. 
   
   
       10 . A necking method of a rectangular can according to  claim 8 , wherein the expansion and the shrinking of the second core and the insertion and the removal of the first core are performed in an interlocking manner with lowering and elevation of the slide.