GB911298A - Method and apparatus for electrostatically applying multi-coatings - Google Patents

Abstract

<PICT:0911298/III/1> Electrostatic coating-apparatus comprises an atomizer array including at least one centrifugal atomizer head, and at least one electrostatic deflector, and means for creating an electrostatic field between the array and the articles being coated, the atomizer head and the deflector being positioned relative each other and to the articles to provide an effective fan-shaped spray pattern emanating from only a part of the peripheral edge of the atomizer head, and for electrostatically depositing the spray on the articles. The electrostatic deflector may be rotatable during the spraying operation and it may itself constitute a spraying head. As shown in Fig. 1, articles 31 are carried around an earthed conveyer 30 and subjected to the spray pattern from a pair of rotary atomizer heads 38 and 40. These are mounted on insulated shafts 42 and 44 of drive motors 50 and 52, mounted with relatively adjustable spacing on a bracket 54. The bracket 54 is connected in a tiltable manner to a piston 58 which is reciprocated vertically by an hydraulic cylinder 60 between limits set by switches 64 and 65. Coating material is supplied to the atomizer heads 38 and 40 from a supply 72 through conduits 73 and 74, connected to feed tubes 75 and 76, and they are charged to a high voltage by a source 100. When supplied with coating material, each atomizer provides a spray of material and repels atomized material from the neighbouring head, so that particles are provided from one position only of the edge of each atomizer. Differently coloured coating-materials may be fed to the atomizers. If no coating material is supplied to one of the heads, it simply functions as a deflector, the rotation providing a cleaning action. Three heads may be mounted on a common bracket, in linear or triangular formation, and their edges may lie in the same or in different planes. Suitable heads are shown in Figs. 3 and 4. In Fig. 3, coating material is fed by a tube 75 to a well 102 of the ring 103 and escapes through openings 104 on to the inner surface of the head and is urged centrifugally to the atomizing edge 101. In Fig. 4, coating material is fed by tube 105 on to a deflecting plate 106 before being urged centrifugally to the edge 101.