GB190216833A - Improvements in Apparatus for Reproducing Phonograms. - Google Patents

Abstract

16,833. Meaeer, W. F. July 29. Moulding phonographic records.-Relates to the reproduction of phonographic records in celluloid or similar material. The celluloid records are produced by expanding a blank record cylinder o against a matrix cylinder a, the inner surface of which bears the sound-record indentations in reverse or negative form. The matrix a is placed upright on the base b and is held in place within the metallic shell c by a backing 8 of plaster-of- Paris. A movable head d is carried by a stem f adjustable by means of a wedge k with respect to the stationary head e. The head d is a trifle smaller than the internal diameter of the matrix a, so as to allow air to escape at n from between the record blank and the matrix. Steam at about 50 lb. pressure is admitted from the pipe r into the pressure chamber p formed by the record cylinder o, bead d, and base b. The heat softens the celluloid, and the pressure expands it against the indented surface of the matrix. The steam supply is then shut off and a valve v is opened to admit cold air under pressure, the exhaust valve y being opened at the same time. When the steam has been blown out, the valve y is closed, cold air under pressure remaining in the pressure chamber until the record is cold and hard. It is then sufficiently shrunken to be removable. To ensure the rapid sealing of the pressure chamber when steam is admitted, channels 5, 7, provided with air outlets 4, 6, are formed in the head d and base b.