GB353510A - Improvements in, and relating to, machines for graining lithographic plates - Google Patents

Abstract

353,510. Grinding. BECKETT, C. A., 138, Ella Street, Hull. April 25, 1930, Nos. 12809 and 30140. [Class 60.] Abrading-medium, article moved in, through, or similarly in contact with.-In a machine for graining lithographic plates, means are provided for removing the spherical graining bodies whilst the machine is in operation. The machine consists of a frame 2 having at each corner a cup 3 carrying a ball 4 to support the graining-trough 5, and within the trough is a false bottom 6 hinged to a cross-bar 8. An extension 9 of the trough carries a well 10 in which are perforated containers 11, or a single wide container, to receive the graining balls, and hinged to the bar 8, or on another axis, so that they may be raised, by hand or mechanical means, to discharge the washed balls on to the plate to be grained. On a cross-bar 15 supported by brackets 14 is hinged an apron 16, which, when lowered closes the trough, and, when raised, allows egress of the balls, abrading-powder and water from the trough. The false bottom 6 is raised by a rope 21 passing over pulleys 22, 23 and wound on a pulley to lift the bottom 6 by gearing actuated by a hand-wheel 28, or the bottom may be raised by fluid pressure or other means. The trough is moved by cranks 36, and upon completion of the graining, and with the trough still in motion, apron 16 is raised and the bottom 6 is lifted so that the balls gradually fall into the container 11 ; a movable plate may be substituted for the apron 16.