Patent GB-190523493-A (GB)
Title: Improvements in the Method of and Apparatus for the Preparation of Curved Printing Plates.
Inventor: TAYLOR ELMER ZEBLEY
Filed: 1905-11-15
Granted: 1906-11-15
Abstract: 23,493. Taylor, B. Z. Nov. 15. Etching; transferring designs &c.-Relates to the preparation of curved printing-plates, particularly for use in rotary colour printing-machines, such, for instance, as are described in Specification No. 4591, A.D. 1904. One object is to produce such plates so that the different plates of a set will accurately register with one another. The curved plate to be prepared is mounted on a cylinder which gears with another cylinder upon which a transfer has been accurately located by means of pins. By rotating the cylinders, the design is transferred to the wetted surface of the plate in the usual way. The plate 5 is now mounted on the cylinder 8, Fig. 2, which is carried by two arms 23 pivoted on a shaft 20. The cylinder can be driven in either direction by belts 12, 13 and an electric or other motor 9, while an endways reciprocating movement is also imparted to the cylinder from the motor shaft. The speeds of the rotary and endwise motions are adjusted so as to be approximately the same. A bath 21 contains etching-material and a bath 22 washing-liquid, and by means of the arms 23 the cylinder 8 can be swung from one bath to the other. Brushes 25 of soft hair &c., removable, if desired, act on the surface of the plates mounted on the cylinder. A cover 24 connects the baths, and a funnel-like cover 26 may serve to carry off any fumes evolved during the etching. The rotating cylinder is not run continuously in the baths, but is occasionally dipped. After the first etching, the plate is washed and dried, and then prepared for a second etching. Powdered bitumen, dragon's blood, &c., impervious to the action of acid, is dusted into the angles formed by the first etching, as shown in Fig. 6. This is done by pushing the plate in one direction beneath an arched brush. The powder is then melted on the plate, the latter cooled and then dusted again in the opposite direction and the process repeated ; if necessary, the plate is also dusted in directions at right-angles to the original direction. In this case, the plate is mounted on a support in bearings so that it may be rotated beneath a brush. The object of this " sealing " of the edges of the design is to prevent the edges from being undercut in the second etching. In order to melt the powder, the plate 5 is mounted on a chamber 32, rotatable in bearings 34 by a wheel 33, Fig. 7. Steam being passed through the chamber 32, serves nearly to melt the powder, but a copper &c, bar 38, supported on arms 50 and heated by gas-jets 53, completes the melting. The arms 50 and the chamber 32 are counterweighted, and stops 52 prevent the bar 38 from being brought too near the plate. The powder having been melted, the plate is cooled by placing it on a flannel &c. pad, supported on a perforated casing through which water under pressure is passed. The flow through the waste pipe may be entirely or partially cut off, and the water may be thus forced through the perforations and the flannel into contact with the plate. The operations of etching, washing, powdering, &c. are repeated as often as is necessary to etch the plate to the desired depth. In some cases, instead of applying and melting powder as described, the plate may have applied to it an ink or other substance which will resist the action of the etching-bath. The plate may then be heated and cooled as before described.