GB1126924A - Electrostatic coating apparatus and method - Google Patents

Abstract

1,126,924. Coating apparatus. RANSBURG ELECTRO-COATING CORP. 23 Sept., 1965 [23 Sept., 1964], No. 40687/65. Heading B2L. Electrostatic coating apparatus for applying to an article a coating with a hammer finish, comprises a device for atomizing coating material for producing finely divided charged particles of the coating material, means for establishing a direct high voltage electrostatic field between the device and the article to promote movement of said particles towards the article, and means for cyclically varying a condition of the apparatus to vary cyclically the size of the deposited particles, whereby to produce a hammer finish on the article. In the embodiment shown coating material is supplied by a pump 28 to the upper surface of a rotating disc 10 which discharges particles of coating material on to articles such as panels 11 circulating around a track 15. The disc 10 is maintained at a high potential with respect to the articles which are earthed and the disc 10 is reciprocated vertically to cover the plates. The reciprocation is effected by pneumatic piston and cylinder 38 connected to lever 32 which is pivoted at 33 and carries a support 21, movement of which reciprocates the motor 18 and disc 10 assembly. The speed of reciprocation is so related to the speed of the articles 11 such that the disc will make several complete cycles of reciprocation during the time required for the articles to pass along the circular track 15. Cyclic variation in an operating condition to cause a variation in the size of the particles of the coating material as, for example by increasing the amount of material delivered to the atomizing disc 10 by increasing the speed of pump 28: by reducing the speed of rotation of disc 10 or by cyclically varying the average voltage gradient of the field between the disc 10 and the article, may be brought about by an extension 45 of arm 32, which extension carries a rod 46 at the lower end of which is mounted a housing 47 containing two switches (75. 76 Fig. 3 not shown) which are then actuated, in accordance with the reciprocation of the disc 10, by adjustable dogs 48, 49.