GB814258A - Apparatus for applying coatings to curved surfaces - Google Patents

Abstract

Apparatus for applying a coating to a curved surface by means of a spray gun comprises two curved contour plates arranged in parallel planes, each plate corresponding with the profile of the curved surface in the respective plane, a beam supported at its ends on the contour plates by rollers or the equivalent arranged to locate the ends of the beam in the planes of the plates and means for traversing the spray gun along the beam. As shown, two curved contour plates 12 and 13 are supported, parallel with one another on frameworks 10 and 11. The article to be coated is at 14. Mounted between the contour plates is a beam 16 having at its ends brackets 17 and 18, each of which carries two rollers (one shown at 19) engaging the inner surface of the respective contour plate. The bracket 17 is rigidly connected with the beam 16, but the other bracket 18 is pivotally connected with a flange 21 on the beam by means of a spherical bearing 22. An indexing shaft 25 running the length of the beam has sprockets 26, 27 at its ends which engage fixed chains 28, 29 lying on the outer edges of the contour plates. An indexing hand wheel 30 is mounted on the beam and geared to the indexing shaft through worm gears 31 and 32. The beam carries a pair of parallel guide tubes 35, 36 on which is mounted a sliding carriage 37 having pivotally mounted thereon a saddle 38 supporting a spray gun 39. The pivotal axis of the connection between the saddle and the carriage, which is formed by two pins 40, passes through the centre of the spherical joint 22, and also through the effective points of contact between the sprockets 26, 27 and chains 28, 29. The two brackets 17, 18 have extensions 41, 42 with spherical joints 43, 44 at their extremities. A guide tube 45 is mounted between these joints. The spray gun and its saddle 38, are provided with rollers (one shown at 46) which engage opposite sides of the guide tube 45. The spray gun is of known kind having automatic feed, providing constant spray delivery. It may include a gas burner 52, and electric motor 51, arranged to feed a metal wire 53 into the flame of the burner, and a compressed air jet arranged to blow the molten metal in finely divided form through the nozzle 50 on to the surface to be coated. The supply of fuel, compressed air and electricity is arranged through flexible leads 54, while the wire 53 is supplied from a drum 56 on the floor beneath the beam. The beam 16 has at its ends sprockets 60, 61 on which is mounted an endless chain 62 which is driven continuously through a geared drive 63 which is connected <PICT:0814258/III/1> <PICT:0814258/III/2> with an external motor 64 through a flexible drive 65. The carriage 37 has means for clutching the carriage to one side or the other of the continuously driven chain 62. This may comprise a transverse slide having dogs arranged to engage selectively with opposite sides of the chain. The slide has at one end a double-ramp formation which is actuated automatically by inclined cams or trip members at opposite ends of the beam. If the surface to be coated has a tapered profile, the two contour plates have different contours corresponding with the profile of the surface at two different stations.