Ring for axial thrust blocking and radial centering of the matrix in an injection moulding apparatus.

摘要

In the production of information media in disc form by the injection-moulding process, there is the risk of streaks forming in the disc, which makes it unusable as an information medium.
Based on the knowledge that the streaking is caused by air which forms in the region of the upper edge of the ring (1) during the injection operation and is compressed by the injection pressure, it is proposed to lead this air away without impairing the centring and thrust-blocking function of the ring and without having to prolong the injection time.