GB492202A - Improved process and apparatus for making rollers with embossed surfaces - Google Patents

Abstract

492,202. Copying by scanning. TAVY, L. DE. May 6, 1937, Nos. 12962, 12963, 12964, and 12965. Convention dates, May 6, 1936, Sept. 29, 1936, Nov. 4, 1936, and Feb. 25, 1937. [Class 40 (iii)] A design element is transferred to emboss a roller A in correct circumferential registration by scanning the carrier 5 with one or more rays of light and recording on the roller or on a coating a on the roller. The scanning controls simultaneously several recording devices 16, 17, which are spaced along the same generatrix of the roller at intervals equal to the axial length of the design element. The carrier of the design is an endless band continuously covered by the design element. When the scanning drum has a diameter which is substantially smaller than that of the roller, the drum is driven at a multiple of the angular speed of the roller but at the same circumferential speed. The individual rollers of a set for multi-coloured printing are produced by repeatedly scanning a single, multi-coloured design, of which the uncoloured parts are impervious to, or do not reflect light, and the colours do not appreciably overlap in the spectrum. For each successive scanning a different light filter is interposed between the source of light 23 and a photo-electric cell 18b. The design is mounted on a hollow tube 90 of elastic material with a longitudinal slit 92 and longitudinal groove 91 on its external surface. The design carrier on the drum is tensioned by tightening the means 94a .. 94c which grip the inner surface of the drum and cause it to rotate. The headstocks 10, 2, which rotate the scanning drum and the roller, are connected by a chain drive 3a, 4a with changeable chain wheels 3, 4, 3b, 4b, and the scanning and recording devices are removably fastened on the carriage 13 of the lathe, and driven by the usual positive, variable gear. The photo-electric cell is connected through an amplifier to the grid of a gas-discharge tube, which is fed with alternating current and is identically connected to each of the recorders, Fig. 4 (not shown). When preparing rollers for colour printing, the operative limit of the relay is adjusted between the successive scans. The recording may be by mechanically controlled light from an electric arc in a high-pressure bulb containing gas and metallic vapour, Fig. 2 (not shown), an electric spark under atmospheric pressure, Fig. 7 (not shown), which may occur between the recording electrode and the roller and be subjected to a stream of oxygen, or a grid-controlled Lenard tube. For mechanical recording a milling cutter 60, Fig. 8, is rotated independently of the scanning and is pressed against the roller by the recording current acting on opposed magnetic fields 71, 72. The cutter removes locally a protective layer a on the surface of the roller. Specifications 322,994, 323,629, [both in Class 98 (ii)], and 470,435 are referred to.