PLASTIC INJECTION METHOD FOR THE PRODUCTION OF AN ELECTRICAL CAPACITOR LID, AND PRODUCT THUS OBTAINED

摘要

The invention relates to a method for the production of a plastic lid that is formed from two different thermoplastic resins which are injected using a double injection machine. The aforementioned lid serves as an upper cover for a capacitor casing, as packing to seal the casing and as a relief valve for the release of gases in the event of overheating. More specifically, the invention relates to a novel design for a lid which is produced using a novel method hitherto unknown in the capacitor industry, thereby rendering said lid different from existing lids. The inventive lid acts as a cover for the casing of a capacitor, as packing for the hermetic sealing of the casing and as a relief valve for the release of gases should the capacitor overheat. According to the invention, the lid is formed from two different injected thermoplastic resins, namely: a rigid resin (17) for the upper part, and a rubber resin (18) for the lower part and the peripheral area of the lid (3). The upper part (17) forms the actual lid of the casing of the capacitor, while the lower part (18) serves as packing for the casing as well as covering a hole in the rigid part (17), such as to form a relief valve (16) for the release of gases.The peripheral rim (3) serves as packing for the casing, while the edge (7) of the rigid part (17) acts as a mechanical grip in order to prevent the two materials from separating. The lid production method involves the use of a double injection machine (4) which employs two moulds simultaneously and which can inject two different resins during the same process.