SELF-SEALING INJECTION DEVICE FOR THERMOPLASTIC MATERIAL

摘要

The invention concerns a device for injecting thermoplastic material. Said device comprises a dispenser (8) which supplies thermoplastic material to a through passage (12) of an injection nozzle (7) which emerges into the moulding cavity (2) and can be sealed by a sliding needle (21). The needle (21) has an extension (24) which passes through the dispenser (8) up to outside air via guiding means (38), to co-operate with controlled means (30) moving the needle (21). Tightness is provided between the extension (24) and the guiding means (38) by the thermoplastic material itself, which leaks between them from the dispenser (8) and accumulates in an annular groove (43) of one of them. The invention is applicable to injection mould devices.