GB493095A - Improvements in or relating to a method of and apparatus for coating cylinders - Google Patents

Abstract

An even coating is applied to a cylinder, e.g. a coating of light-sensitive solution to a rotogravure cylinder, by simultaneously combining, during the setting or congealing of the coating, a flow of the coating produced by the rotating of the cylinder about its axis with a gravitational flow towards the ends of the cylinder produced by alternately positioning one end of the cylinder lower and then higher than the other, e.g. by bodily rocking, tilting or oscillating the cylinder about a horizontal axis transverse <PICT:0493095/III/1> to the cylinder or about an axis inclined to the vertical sufficiently to produce the necessary endwise flow of the coating. Apparatus for carrying-out the process comprises a support A provided with a shaft 16 from which is suspended a carriage B for the cylinder 47 to be coated. The carriage B comprises a base 17 supported from the shaft 16 by diagonal plates 18 and provided with guideways 19 for adjustable supports 20. Horizontal bars 25 carried by transverse plates 24 on the carriage B pass through the supports 20 and are provided on the underside with teeth 26 engaging pinions on transverse shafts 27, 28 mounted on each support 20. The shafts 27, 28 carry gear wheels 31 engaged by chains 32, so that, by rotating the shafts 27, supports 20 are adjusted along the carriage B. Each support 20 carries a vertically-adjustable crosshead 35, provided with a nut 36 engaged by a screw 37 mounted on the supports, the screws 37 carrying gears 39 which engage gears 40 splined on a shaft 41, the rotation of which adjusts the crossheads 35 simultaneously. The crossheads 35 carry brackets 43 provided with bearings 44 for supporting rollers 45 adapted to carry the cylinder 47 to be coated. The supports 20 are provided with arms 48 along which the cylinder 47 is run into position, after which the rollers 45 are raised to engage the shaft 46 of the cylinder. Each bracket 43 carries a rigid arm 52 on which is adjustably mounted a post 53 carrying an adjustable end-thrust bearing 56 adapted to engage the end of the shaft 46; the <PICT:0493095/III/2> posts 53 also carrying adjustable locking rollers 60 which are brought into engagement with the upper part of the ends of the shaft 46. The cylinder 47 is rotated through a grooved pulley 67 secured to the shaft 46 and a motor 70 adjustable in arms 71 on one of the supports 20. The carriage B may be provided with mechanical means by which it is tilted or oscillated comprising a driven shaft 80, a crank arm disc 82, a link 84 pivoted to a rack 87 engaging a pinion 88 on a shaft 89, a larger pinion 90 on the shaft 89 and engaging a second rack 91, and a link 93 connecting the rack 91 to an arm 94 rigid with the carriage B. A drip trough 75 is supported on the upper ends of the supports 20 and is provided with spouts 76 leading to receptacles 77. In use, the cylinder 47 is rotated and liquid coating material is applied thereto in any manner, e.g. by hand, with the cylinder either horizontal or inclined; after draining, the cylinder is then tilted or oscillated either by hand or mechanically, the rotation being continued, until the coating has set.