Battery case lid and manufacturing method for battery case lid

Abstract

A battery case lid is formed by working a metal plate, and includes a substrate section and an explosion-proof valve formed in the substrate section. The explosion-proof valve has a reduced thickness section that is thinner than the substrate section, and the reduced thickness section is formed by extending the metal plate by applying pressure while the metal plate is kept unrestrained.

1 - 16 . (canceled) 
     
     
         17 . A battery case lid formed by working a metal plate, the battery case lid comprising:
 a substrate section; and   an explosion-proof valve formed in the substrate section,   
       wherein
 the explosion-proof valve has a reduced thickness section thinner than the substrate section, the reduced thickness section being formed by extending the metal plate by applying pressure with the metal plate kept unrestrained, and 
 the explosion-proof valve is surrounded by a folded part thicker than the reduced thickness section, the folded part being formed by folding the metal plate, and 
 
       wherein
 the reduced thickness section is thinner than a thickness of a metal plate layer forming the folded part. 
 
     
     
         18 . A battery case lid formed by working a metal plate, the battery case lid comprising:
 a substrate section; and   an explosion-proof valve formed in the substrate section,   
       wherein
 the explosion-proof valve has a reduced thickness section thinner than the substrate section, the reduced thickness section being formed by extending the metal plate by applying pressure with the metal plate kept unrestrained, and 
 the explosion-proof is surrounded by a folded part thicker than the reduced thickness section, the folded part being formed by folding the metal plate, and 
 
       wherein
 the folded part horizontally extends around an entire outer periphery of the explosion-proof valve. 
 
     
     
         19 . The battery case lid formed by working a metal plate according to  claim 18 , wherein the folded part is a part folded in three ring-shaped metal-plate layers formed in the substrate section. 
     
     
         20 . The battery case lid formed by working a metal plate according to  claim 18 , wherein the metal-plate layers forming the folded part are gradually decreased in thickness from the bottom to the top layer. 
     
     
         21 . A manufacturing method for a battery case lid including an explosion-proof valve, the manufacturing method comprising:
 pushing an extending punch from a first side of a metal plate disposed over an extending die having a recess, to form a reduced thickness section constituting the explosion-proof valve,   
       wherein
 the recess has an inner diameter greater than an outer diameter of the extending punch, 
 
       wherein
 a clearance between a side face of the recess of the extending die and an outer periphery at a top section on a side face of the extending punch is set to be smaller than a thickness of the metal plate, the top section being formed by an end of the extending punch facing the recess, and 
 
       wherein
 the extending punch is pushed while the metal plate is kept unrestrained, and the metal plate is pressed to be extended between a bottom face of the recess and a pressing face of the extending punch, to form the reduced thickness section and a cylindrical wall portion at least until a gap is formed between the metal plate and the outer periphery at the top section on the side face of the extending punch. 
 
     
     
         22 . The manufacturing method for the battery case lid of  claim 21 , further comprising forming a groove in the reduced thickness section. 
     
     
         23 . The manufacturing method for the battery case lid of  claim 21 , wherein the cylindrical wall portion is formed around the reduced thickness section, the cylindrical wall portion having a height greater than a depth of the recess of the extending die. 
     
     
         24 . The manufacturing method for the battery case lid of  claim 21 , further comprising pressing the reduced thickness section by a bending punch smaller in outer diameter than the reduced thickness section from a second side of the metal plate, to bend the cylindrical wall portion formed around the reduced thickness section. 
     
     
         25 . The manufacturing method for the battery case lid of  claim 24 , further comprising pushing a bent portion formed by bending the cylindrical wall portion by a folding punch from the second side of the metal plate, to fold the bent portion. 
     
     
         26 . The manufacturing method for the battery case lid of  claim 21 , wherein the pressing face of the extending punch has a spherical face which is convex in a pressing direction of the extending punch. 
     
     
         27 . The manufacturing method for the battery case lid of  claim 21 , wherein a lateral protrusion is formed around the outer periphery at the top section on the side face of the extending punch. 
     
     
         28 . The manufacturing method for the battery case lid of  claim 27 , wherein the lateral protrusion has a semi-circular shape protruding outwardly in cross section. 
     
     
         29 . The manufacturing method for the battery case lid of  claim 21 , further comprising correcting the reduced thickness section to be flat. 
     
     
         30 . A battery case lid manufactured by the manufacturing method according to  claim 21 , the battery case lid comprising:
 a substrate section; and   the explosion-proof valve formed in the substrate section,   
       wherein
 the explosion-proof valve has the reduced thickness section thinner than the substrate section, and 
 the explosion-proof valve is surrounded by the cylindrical wall portion thicker than the reduced thickness section, and 
 
       wherein
 the cylindrical wall portion has a thick base portion and a tapered portion, and 
 the tapered portion gradually decreases in thickness from an end portion of the base portion to the reduced thickness section. 
 
     
     
         31 . A battery case lid manufactured by the manufacturing method according to  claim 25 , the battery case lid comprising:
 a substrate section; and   the explosion-proof valve formed in the substrate section,   
       wherein
 the explosion-proof valve has the reduced thickness section thinner than the substrate section, and 
 the explosion-proof valve is surrounded by a folded part thicker than the reduced thickness section, the folded part being formed by folding the metal plate, and 
 
       wherein
 the metal plate is not annealed. 
 
     
     
         32 . The battery case lid of  claim 30 , wherein a groove is formed in an upper face of the reduced thickness section. 
     
     
         33 . The battery case lid of  claim 31 , wherein a groove is formed in an upper face of the reduced thickness section. 
     
     
         34 . The manufacturing method for the battery case lid of  claim 24 , further comprising forming a groove in the reduced thickness section, wherein the reduced thickness section is pressed by a groove forming punch from a second side of the metal plate to form the reduced thickness section with a groove. 
     
     
         35 . The manufacturing method for the battery case lid of  claim 25 , further comprising forming a groove in the reduced thickness section, wherein the reduced thickness section is pressed by a groove forming punch from a second side of the metal plate to form the reduced thickness section with a groove. 
     
     
         36 . The manufacturing method for the battery case lid of  claim 26 , wherein the bottom face of the recess has a spherical surface which is downwardly convex, and a curvature radius of the spherical face of the pressing face is equal to or smaller than a curvature radius of the spherical face of the bottom face of the recess.