process for the manufacture of gramophone records and press for injection moulding: a to the line of the procedure

摘要

1,071,340. Injection moulding gramophone records. DECCA Ltd. Nov. 23, 1965 [Jan. 27, 1965], No. 3530/65. Heading B5A. A gramophone record is made by a method comprising injecting a material such as that described in Specification 1,071,331 through a nozzle 20 into a gap between a movable die 12 and a fixed die 10, moulding the material as described in Specifications 1,071,332, 1,071,333, 1,071,334 and 1,071,335, and then removing the die 12 with the record attached thereto, air being injected in synchronism with the movement of the die 12 through six orifices 32, each of one thousandth of an inch diameter, into the gap between the record and the fixed die 10 to break the vacuum. The dies are maintained at the same temperature (65‹ F. at the inner periphery, 120‹ F. at the outer) by water circulating through annular channels 23, 25, 28 therein the record is removed by ejector pins 21 which withdraw automatically as soon as the record is released by a method described and claimed in Specification 1,071,341. Attraction of the released record to either die due to electrostatic forces is obviated by blowing ionized air over the record, as described and claimed in Specification 1,071,337. The record may be embossed with a sound track or may be a blank disc for use in a two-part process by use of suitable matrices 14, 15.