GB908431A - Method of and apparatus for mounting printing plates - Google Patents

Abstract

908,431. Printing-surfaces. ORCHARD PAPER CO. Dec. 18, 1959 [July 2, 1959], No. 43061/59. Class 100 (2). A method of mounting printing plates on a printing cylinder comprises providing a mark on the cylinder parallel with the axis thereof, mounting a transparency of the design to be printed, incorporating a registering mark, on one side of a flat, transparent support, detachably securing a printing plate to the same side of the support in registration with a corresponding design portion of the transparency, presenting the support-mounted printing plate to the cylinder while the registering mark on the transparency is in registration with the mark on the cylinder, securing the printing plate to the cylinder and thereafter detaching the support from the printing plate to leave the plate affixed to the cylinder. As shown, in order to prepare them for printing a design in two colours two printing cylinders 15, 16 are rotatably mounted in V-shaped bearings 14, 14<SP>1</SP> formed in blocks 9, 10. The blocks 9, 10 are secured to two beams 1, 2, which form part of the main frame of a device for carrying out the method of the invention, and are adjustable longitudinally of the beams so as to accommodate cylinders of different lengths. A gear 17, 18 is mounted on the portion of each cylinder shaft which projects beyond the block 9. The gears 17, 18 mesh with a gear 19 mounted on a shaft 20 which is journalled in a bearing 21 vertically adjustably secured to the machine frame. A wheel 26 also mounted on the shaft 20 carries a scale 28 the movement of which in relation to a fixed arm 29 denotes the amount of angular movement imparted to the printing cylinders by rotation of the shaft 20. Rotation of the shaft 20 is effected by means of a hand wheel 35 through a worm-and-pinion arrangement. Slide-bars 8 are mounted on the upper sides of beams 1, 2 and serve to guide a carriage B capable of longitudinal sliding movement on the main frame. The carriage B comprises a lower transverse member 37, side members 38, 39, and an upper transverse member 40. The member 40 comprises a pair of spaced-apart runners 40a, 40b which support a slide 41; a shaft 74 journalled in bearings on the slide 41 has a hand wheel 76 mounted at one end and a pinion 75 at the other, the pinion meshing with a rack 77 on the runner 40a whereby rotation of the wheel 76 causes transverse movement of the slide 41 in relation to the cylinders 15, 16. Stabilizers 51, 52 are secured to the underside of the runners 40a, 40b at right-angles thereto and bear on tops of the beams 1, 2 inside the slide-bars 8. Angle-pieces 53 at each end of the stabilizers engage with their undersides the upper surfaces of the slide-bars. Longitudinal movement of the carriage B is effected by turning either of two hand wheels 47, 48 mounted on a shaft 42 journalled in the carriage side members; pinions 43, 44 on the shaft engage racks 45, 46 secured to the underside of the beams 1, 2. Two panel support structures C, C<SP>1</SP> are mounted for both vertical and horizontal adjustment on the slide 41 and each supports a glass panel 62 which is hinged thereto at 60 and is pivotable between a position in which it engages the adjacent printing cylinder and a position in which it rests upon a stop 69. Each cylinder 15, 16 has a score line 90 inscribed thereon parallel to the axis of the cylinder. In use of the device the cylinders are rotated until the lines 90 thereon face upwards. As the design 81 is to be printed in two colours two sorts of printing plate 86, 87, Fig. 16, bearing different parts of the design are necessary. The plates may be made of rubber. A transparency 80 bearing a representation 81 of the complete design to be printed, portions 82, 83 of the repeats of such design, and a transverse centre line 84 is stuck on to the underside of each glass panel 62 in such a position that the lines 84, 90 are in register, Fig. 11, the carriage B having previously been moved to a position adjacent to one end of the pair of cylinders. The panel 62 carried by the support C is raised and a plate 86 is lightly stuck to the underside of the transparency 80 secured thereto, the design on the plate being in register with the corresponding part of the design 81 on the transparency. The underside of the plate 86 is liberally coated with adhesive and the panel 62 is swung downwards until the plate 86 engages the cylinder 15 and sticks thereto. When the panel 62 is subsequently raised the plate 86 breaks away from the transparency 80 and remains on the cylinder. Further plates 86 longitudinally aligned with the first are secured to the cylinder 15 by moving the carriage B into a position where the repeat portion 82 on the transparency 80 registers with the previously applied plate and repeating the procedure previously described. When a complete row of plates has been affixed to the cylinder 15 the cylinders are rotated through the desired angle by means of the hand wheel 35 and a further row is affixed. The cylinder 15 is shown in readiness for printing in Fig. 16. When the securing of plates to the cylinder 15 has been completed the two cylinders are rotated until the lines 90 thereon are again uppermost and the carriage B is moved to a position wherein the design 81 on the transparency carried by the support C is in register with the plate 86 initially applied to the cylinder 15. A second transparency 80 is then fixed to the underside of the panel 62 carried by the support C<SP>1</SP>, the line 84 thereon being registered with the line 90 on the cylinder 16. Thereafter printing-plates 87 are mounted on the cylinder 16 in the same way as the plates 86 were mounted on the cylinder 15, precise alignment of the plates 87 being further ensured by the registration of the design 81 on the first transparency 80 with the corresponding plate 86 on the roller 15. By use of the same apparatus rubber plates may be secured on a printing cylinder so as to register with design portions on engraved copper cylinders as used in the rotogravure process.