Patent GB-736002-A (GB)
Title: Improvements in or relating to methods of and apparatus for preparing stereotype, electrotype, plastic or other plates for colour printing
IPC: G03F9/00
Filed: 1951-09-07
Abstract: 736,002. Printing-surfaces. R.B. PRODUCTION & ENGINEERING CO., Ltd., and RIGG, E. W. D. Dec. 8, 1952 [Sept. 7, 1951], No. 21161/51. Class 100 (2). A method of preparing multi-colour printing plates comprises drilling a plurality of pairs of holes in a base, the holes of every pair being of the same spacing, mounting a plurality of original colour plates on the base, each plate being associated with a respective pair of holes, preparing a plurality of sets of duplicate colour plates comprising pairs of holes equivalent to the holes associated with the original plates, and mounting each set of duplicate colour plates on a base. Printing is effected first from one set and then from another set, the equivalent pairs of holes of the duplicate colour plates being used to ensure that all the sets of duplicate colour plates are of identical spacing and orientation, so that the several printings will register with each other. As shown in Fig. 1, the apparatus for carrying out the method comprises a bed 1 on which a drilling board 2 is placed which supports a slide block assembly 3 together with a rectangular frame 4. The frame 4 is adapted to be moved laterally on tracks 6 by a screw 8 and co-operating nut 10 fixed to the frame 4 and operated by a handle 15. Lateral positioning of the block 3 is thus effected. Longitudinal movement of the block 3 is achieved by means of a similar arrangement 18, 19, 20, the screw 18 being journalled in the frame 4 and positioning the block 3 longitudinally within the frame. Markers 17 and 22 are provided so that the exact position of the block 3 may be determined. The slide block assembly 3 comprises a shallow block 23 which has therein a hole in which is mounted a rotatable ring 24, having a member 25 secured thereto. The member 25 is provided with adjustable drilling bushes 27 having holes 28 therein through which a drill 31 may be passed. The rotatable ring 24 is provided with a number of holes 29 which may be registered with a hole in the block 23 by means of a screw 30 for setting the ring in the required position. In order to prepare duplicate plates for printing a metal plate 36 is fastened to the drilling board 2. A piece of celluloid 37 (Fig. 2) large enough to cover a colour plate is fastened on the plate, the slide block assembly 3 moved into position over it and two holes 38 drilled therein. The celluloid is then removed and the slide block assembly moved longitudinally a distance greater than the width of a plate and a plurality of equally spaced holes 38 are drilled on the plate 36. A lateral adjustment of the assembly 3 may be made and a second row of holes drilled. A colour plate 41 (Fig. 4) is then secured by adhesive to the plate 36, inked, and a print taken on celluloid 37, pins 44 having been placed in the holes 38 to keep the celluloid supported at the height of the plate. The celluloid is then placed over successive holes 38 and the respective colour plates 41, 43, 45 aligned therewith and stuck in position on the plate 36 (Fig. 6). Pins 46 (Fig. 9) are then inserted in place of the pins 44 (Fig. 7), a mould is taken, and a duplicate cast of the composite plate. The individual duplicates are then severed, trimmed, and holes 47 (Fig. 11) drilled therein corresponding to the positions indicated by the pin 46. A plurality of such duplicates are made and mounted on a plate 48 (Fig. 12). To this end the plate 48 is mounted on the board 2 and the assembly block 3 set in the same angular position as when the original holes 38 were drilled, the drilling bushes being moved closer together owing to shrinkage of the plates during casting. A plurality of holes are then drilled similar to the holes 38 and the plates mounted by tacks 50 through the plate 48 on a mounting board 49. Subsequent colour plates are mounted in the same manner using the holes already drilled in the plate 48, so that successive prints are in register. The plates may alternatively be mounted over headless tacks engaging holes drilled part way through their rear surfaces. In this case the duplicate plates are prepared in the same way as above including their holes 47 (Fig. 11). The rotating element 25 of the assembly 3 is then removed and replaced on another block 51 (Fig. 13) which replaces the block 23. The block 51 has a plate 52 provided with slots 53 in which are adjustable locating pins 55. The pins 55 are registered with the holes 47 in the duplicate plates 41d and holes in the required position drilled in the back of the plate through the bushings 27. The rotatable element 25 is then returned to the slide block 23 of .the machine and adjusted to a position which it occupied on the block 51 and pairs of holes are drilled in the plate 48 which is subsequently tacked to the board 49 by short tacks which engage and register with holes drilled in the back of the plate. The plates are also secured by adhesive.