GB748774A - Improvements in or relating to spraying apparatus - Google Patents

Abstract

Apparatus for spraying articles comprises stationary walls enclosing a spray zone which is closed except for an opening or openings to pass the articles to be sprayed, conveyer means to convey articles through the openings into the spray zone, and spray means in the housing discharging a spray of material on to the articles as they advance through the spray zone, all exposed stationary surfaces above the path of the article including the top walls, sloping at an angle of at least 45 degrees with respect to the horizontal, with their entire exposed lower edges disposed beyond and at the side of the path of the articles, so that spray material which is intercepted thereby flows along the sloping surface and is discharged beyond the path of the articles. As shown, the apparatus comprises a housing having end walls 10 and 11 and side walls 12 having top walls 13 hinged thereto, and inclined bottom walls 14, the walls 12, 13 and 14 being jacketed for circulation of a heating or cooling medium, such as hot or cold air. The bottom walls 14 slope towards a sump 15, and the top walls slope upwards at an angle of more than 45 degrees to meet in the centre line, the slope being such that oversprayed material caught on the walls flows downwardly towards the sump 15, without dropping off on to the articles being sprayed, and flows to a receiver through a drain pipe 17. Louvres, not shown, may be attached to the top walls to assist in preventing drips. The end walls 10, 11 have openings 30, 31 to permit passage of the articles 63 to be sprayed, which are supported on pins 61 on a conveyer chain 60. Drain gutters 34, 35, along the inclined top edges of the openings 30, 31, prevent spray material from draining on to the passing articles. Vestibules 36, comprising jacketed side walls and bottom walls 38 and 40 respectively, are aligned with the openings 30, 31 to shield the latter and prevent loss of spray and shields are provided to direct the spray away from the exit. The vestibule 36 at the entrance side is provided with inwardly-opening doors 55 hinged to the wall 39 and urged to closed position by springs 53. Certain of the pins 61 may be provided with cross bars 65 to engage and open the doors 55. The vestibule at the exit side may be provided with similar, but outwardly opening, doors, or its end wall 57 may have an opening closely fitting the articles and be provided with an inwardly-extending shield 58 with an upturned lip 59. Openings 70 are provided in the end wall 11, or, in a modification, in <PICT:0748774/III/1> <PICT:0748774/III/2> <PICT:0748774/III/3> <PICT:0748774/III/4> both end walls, to receive spray guns 71 which are carried by plates 74 secured to the walls, or by a form of universal mounting, the holes 70 then being covered by flexible diaphragms. The spray guns, as shown in Fig. 13 are of a type having centrifugal distributers and rotary cases, and each has a fixed housing 80 havin a bore 81 in which is journalled a hollow shaft 82, on one end of which is a gear 101 meshing with a further gear 103 on a separate shaft 104, which is coupled to a driving shaft such as a flexible cable 111 (Fig. 1). The other end of the shaft 82 carries a rotary case 85, the outer flange 86 of which has a channel 87 in which the spray material is caused by the rotation to form an annular film. The case 85 carries an annular flange 93 which extends over the lower grooved end of the housing 80, to form a seal. A stationary hollow shaft 112, clamped to the housing, extends through the shaft 82 and carries a bracket 115 on which is a hollow stud 117. The hub of a distributer 119 is journalled in the stud 117 by ball bearings 120; the outer surface of the distributer 119 carries fins 121 terminating on a conical surface, and dipping into the film of spray material, being driven thereby and picking up the material and projecting is as a fine spray. The axis of the distributer is set at an angle to that of the case 85, and may also be tilted with respect to the diametrical plane through the case in which it is contained. A flange 120a shields the stud 117 from the spray. The spray material is introduced into the casing 85 from a hose or pipe 131 (Fig. 1) through a coupling 130 and the bore 125 in the shaft 112, which communicates with bores 126 and 127 in the bracket 115. The apparatus may be used for applying paint, varnish, lacquer or glaze for ceramics. The walls of the housing may be heated when hot spray or melted materials are used, or cooled when it is desirable to condense solvent vapour, the enclosed spraying zone allowing the atmosphere therein to be controlled.