| CPC B21D 26/021 (2013.01) [H01M 50/224 (2021.01); H01M 50/231 (2021.01)] | 12 Claims |
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1. A method of forming a shell of a soft pack battery comprising the steps of:
a material preparing step which includes a step of preparing a thin sheet material, a preform mold, and a final-forming mold; two opposite sides of the thin sheet material are provided with a first surface and a second surface correspondingly; the preform mold and the final-forming mold are respectively provided with a preform mold cavity and a final-forming mold cavity while a first depth of the preform mold cavity is smaller than a second depth of the final-forming mold cavity; wherein the thin sheet material is selected from the group consisting of aluminum-plastic film, stainless steel, and titanium and having a thickness of 0.02 mm-0.2 mm and an elongation at room temperature of 10%-20%;
a preforming step which includes steps of
adjusting a temperature of the thin sheet material to a working temperature and mounting the thin sheet material into the preform mold while the second surface of the thin sheet material is facing toward the preform mold cavity; and
generating a first fluid pressure and a second fluid pressure respectively on the first surface and the second surface of the thin sheet material while there is a first pressure difference between the first fluid pressure and the second fluid pressure; owing to the first pressure difference, the thin sheet material is deformed from the first surface toward the second surface until the second surface is in contact with the preform mold cavity to form a preform with a first cavity; wherein the working temperature is between room temperature and recrystallization temperature of the thin sheet material, or between the room temperature and glass transition temperature of plastics;
wherein a bottom of the preform is provided with at least one compensation portion;
a final-forming step having the steps of:
maintaining a temperature of the preform at the working temperature and disposing the preform into the final-forming mold while the second surface is facing toward the final-forming mold cavity; and
generating a third fluid pressure and a fourth fluid pressure respectively on the first surface and the second surface while there is a second pressure difference between the third fluid pressure and the fourth fluid pressure; owing to the second pressure difference, the preform is deformed from the first surface toward the second surface until the second surface is in contact with the final-forming mold cavity to form a final formed part with a second cavity; and
taking the final formed part out of the final-forming mold and then cooling down to the room temperature naturally.
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