GB312532A - Improvements in method of forming molds for printing plates and molds formed thereby - Google Patents

Abstract

312,532. Claybourn, L. W. July 9,. 1928. Printing-surfaces.-To prevent certain parts of electrotype or other thin printing-plates from being injured, when pressed against a flat surface to level up the printing-surfaces, or when bent around a cylinder and acted on by pressure for the same purpose, the surfaces are formed with bearer areas of the same height as the printing- surfaces, and these areas take the pressure and prevent injury to the printing areas. The bearer areas may be subsequently removed by routing tools before the printing operation. The printing- surfaces are cast from moulds 42, Fig. 6, such as wax moulds on a metal base, and after the design to be printed has been impressed into the mould, the bearer areas are formed by cutting out grooves 51, Fig. 14, in the mould by means of a cutting tool 53 formed with a sharp bottom and sides and with curved front parts 55, 56 which facilitate the removal of waxed strips. The mould is clamped to a table while the cutter acts, and means are provided for adjusting the cutter in a plane perpendicular to the plane of the mould and for setting it at the same height as the bottom of the depressions produced by the printing-surfaces. The tool or table is traversed to cut out desired areas, such as rectangles, and when the printing-surface is cast, bearer areas 38, Fig. 13, of the same height as the printing surfaces 31 are formed in the moulded plate. Rough edges produced by the cutting-tool may be removed by momentary application of heat. After the printing-plate has been trued up on a flat surface or a cylinder under pressure, the areas 38 are removed by a routing tool.