GB190207146A - Improvements in the Method of Forming Duplicate Sound Record Cylinders of Celluloid or similar Materials and the Apparatus and Devices connected therewith. - Google Patents

Abstract

7146. Petit, A. N. March 24. Moulding phonograph records. - Relates to the production of celluloid &c. phonograph records from a master record. A master record a, Fig. 2, is treated with plumbago to render the surface conducting, and is fitted with a cap 3, on the outer sloping face of which the name of the record is cut. Copper end-pieces c, d are then employed to hold the record in position and to form suitable end portions of the electrodeposited mould of copper, which is built up to the dotted line ; b is a detachable base-plate and 6, 6 are the electric connecting-wires joining the two end-pieces to the lead. The mould c, Fig. 1, fitted with a celluloid blank f having..an inturned flange at the upper end, and a folded portion at the end, is then fitted on to a base-plate g, pressure rings and packing k being fitted to each end by extension rods m to form airtight joints, so that air and moisture can be exhausted from between the mould and blank faces ; 9 is a screw valve to close this connection when the mould is ready for insertion into the heating and pressure chamber. The mould is shown in the pressure chamber n, there being accommodation for a number of such moulds. The chamber is closed by a lid, and steam or hot water admitted under pressure. After moulding, the records are shrunk out of the moulds by cooling the chamber with cold water.