Improvements in or relating to casting boxes for stereotype plates

摘要

622,981. Stereotype. GOSS PRINTING PRESS CO., Ltd. March 6, 1947, No. 6350. Convention date, May 17, 1946. [Class 100 (ii)] In a casting box for stereotype plates having a pair of shells defining a casting space and supporting a matrix, and each having a vacuum chamber within it which communicates with its inner surface through ports in its inner wall, the shells are hingedly interconnected by means having ports or passages therein to interconnect the vacuum chambers and ensure continuous equalisation of pressure in the latter. The hinge mechanism comprises gudgeons 26, Figs. 3 and 4, connected to the shells 10, 11 and a pintle 25 having an axial passage 27 communicating with an air pump operated by an electric motor controlled by a switch 40 closed automatically when the casting box is shut. The gudgeons of the shell 10, which is stationary, are pivotable relatively to the pintle, which has a pressed fit in the gudgeons of the shell 11 and is rotatable therewith to open the box. Passages 29 in the lowermost gudgeon of each shell communicate with pores 28 in the pintle and with the vacuum chambers 23 in the shells, whereby all the chambers 23 in both shells are in continuous communication. A sleeve 30, gaskets 31, 32, and a stuffing-box 33 are provided for the lowest gudgeon of the shell 10 to prevent leakage of atmospheric air into the chambers, the sleeve having ports 36 and an annular relief 35 to maintain communication.