Gasket, method of molding same, and cylindrical alkaline-manganese dioxide cell using same

A method of molding a gasket using a mold assembly which comprises:

• assembling a male and female mold, which when assembled define spaces into which a resin is filled to mold a gasket, said spaces comprising:
• a cylindrical space;
• a disc-shaped space positioned along the outer circumference of the cylindrical space;
• a curved space contiguous to the outer circumference of the disc-shaped space;
• and
• a narrow space resulted from a projection formed on the male mold between the cylindrical and disc-shaped spaces, the projection being chamfered or curved at a side thereof facing the cylindrical space and directed downward in the direction of the female mold;
• the male mold having formed therein an injection gate open at the top of the cylindrical space;
• and
• at least any one of an ejector sleeve formed on the female mold at the bottom of the cylindrical space and an ejector pin formed in the curved space, being provided for the resin to be filled uniformly into the mold assembly.

A cylindrical alkaline-manganese dioxide cell including a can open at one towards the lower end thereof, the can opening being sealed with a gasket comprising:

• a cylindrical portion whose lower portion is gradually increased in thickness towards the lower end thereof, having formed therein a hole open at the top and bottom thereof, the lower opening being larger than the upper one, and in which a current collector is to be inserted;
• a disc-shaped portion formed contiguously along the outer circumference of and concentrically with the cylindrical portion;
• a thin portion formed between the cylindrical and disc-shaped portions, concentrically with the cylindrical portion and in a position nearer to the bottom of the disc-shaped portion;
• and
• a peripheral portion formed contiguously along the outer circumference of the disc-shaped portion to have the axial-sectional shape of a curve;
• the cylindrical portion being formed to project at the lower end thereof downward from the bottom of the disc-shaped portion;
• the boundary between the cylindrical and thin portions being chamfered or curved;
• and
• the boundary between the disc-shaped and thin portions being formed like a generally vertical edge.