Resistance heated moulds - particularly for compression moulding gramophone records

摘要

Moulding press for thermoplastic masterials, particularly for the production of gramophone records of the type in which two opposed moulds, fixed to cooled mould platens, can be heated by resistance heating in such a way that electric current flows through the electrically insulated moulds themselves in contrast to the mould platens, with the improvement that each mould is incorporated in a circuit independent of that of the other mould and that the current intensity can be controlled in at least one circuit while the currents in both circuits can be regulated relative to one another as a function of the resistance of the appropriate mould in such a way that the temp. of the moulds is the same.