GB875904A - A lithographic printing machine - Google Patents

Abstract

875,904. Printing machines. HARDY, R. V. M. Aug. 5, 1959, No. 26710/59. Class 100(2) A lithographic printing machine comprises a base 1, 2, 3, an inking support 21 and an offset pad 23 mounted in spaced positions on the base, and a lithographic plate carrier 7, 8 pivotably mounted on the base between the support and the pad and movable about its pivot to position it selectively on the support 21 for inking of the plate and on the offset pad 23 for transfer of the inked impression. Prinfing surfaces. The carrier 7, 8 is pivoted to the base at 6 and has a cross-bar 9 to which one end of a flexible lithographic plate 10 is secured, holes in the plate being engaged over pegs 11 on the bar 9 and a keeper-bar 12 then being placed over the pegs and secured thereon by knurled nuts. The other end of the plate 10 is secured in similar fashion to a bar 15. The bar 15 has a metal tongue 14 projecting from each end which is slidable in a slot 13 in the corresponding side member of the carrier. Cords 19 pass through eyelets 18 at the outer end of the carrier and connect the tongues 14 to the opposite ends of a tension spring 20 whereby the plate 10 is kept under tension. Offset surfaces. The offset pad 23 comprises a blanket stretched over the curved upper surface of a rigid block 22. The blanket is firmly secured to the block 22 at the end near the pivots 6 and at the opposite end to a tie bar 25. The blanket is tensioned by means of screws 26 which pass through holes in a cross-member 27 of the base and are engaged by knurled nuts 28. Platen machines. In use the carrier 7, 8 is first positioned so that the plate 10 is supported by the support 21 and may be inked and damped by a hand roller. The carrier is then pivoted through almost 180 degrees until the inked surface of the plate is in contact with the pad 23, the image being transferred to the blanket by the application of a dry roller to the back of the plate. The carrier is finally moved to the Fig. 1 position to allow paper to be put on the offset pad. An impression is taken by rolling the paper on the back with a dry roller. Guide plates 29, 30 mounted on the base help maintain register of the plate 10 with the pad 23. Stencilling. The plate 10 may be replaced by a silk screen, pigment being forced through the screen on to a sheet of paper on the block 22.