Injector for pressurised gas into a mould for making a plastic item, mould and moulding method using such an injector and plastic item thus obtained.

摘要

The injector (20) is constituted by a tubular sheath (24) fixed in a wall (5) of the mould and by an injector needle (32) engaged in a fixed position in the internal bore of the sheath (24). The injector needle (32) is pierced by a pressurised-gas supply channel (37) which communicates with an annular injection chamber (40) delimited between the inner surface of the sheath (24) and the external surface of the injection needle (32). The end portion (24a) of the injector projects into the cavity (8) of the mould. In this end portion of the injector, the annular injection chamber (40) has a very small width corresponding to the radial clearance between the sheath (24) and the injection needle (32). The diametral clearance between the sheath and the injection needle in the end portion is approximately 0.05 mm. The mould may comprise at least one injector (20) whose end portion projects into a cavity (27) for producing a rib for reinforcing the part. The pressurised gas may be injected during the injection phase of the plastic into the cavity (8). The plastic part may comprise hollow reinforcement ribs. <IMAGE>