CS204127B1 - Device for electrostatic coating the workpiece by the powder - Google Patents

Description

THE CZECHOSLOVAK SOCIALIST REPUBLIC (19) DESCRIPTION FOUND TO COPYRIGHT CERTIFICATE, 204127 (11) (Bl) - (51) Int. Cl.3 B 05 B 5/08 (22 j Registered 07 12 76 (21) (PV 7974-76) (32) (31) (33) Priority from 10 12 75 (WP B 05 b / 190,000) German Democratic Republic (40) Published on 31 07 80 0 * AD FOR EXTRAORDINARY AND DISCOVERY (45) Published 15 12 63 • (75)

Author of the invention RINGEL JĎRGEN dipl. ing., KLEBER WOLFGANG dr. ing., AUERBACHDIETER dr. and BAUCH HELMUT dr. ing., DRESDEN (GDR) (54) Equipment for electrostatic coating of workpiece 1

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a device for electrostatically coating a workpiece with a powder consisting of a submersible container with at least one ejector, the mixing tube of which simultaneously constitutes an electrokinetic charging device, the coating being carried out by immersing the workpiece in a powder cloud. from electrically charged particles. GDR pat. No. 113,289, which is the state of the art, has been proposed to provide a powder dispensing apparatus in a powder reservoir whose powder charge is fluidized through the porous surfaces of the bottom and walls, and the powder is continuously aspirated by means of electrical charging. the ejector so that the upper part of the immersion tank is reinserted after the electrical charge has been passed. The coating process is carried out by immersing the workpieces having a potential charge opposite to the charge particles, preferably the ground potential, into the fluidized bed and / or into the discharge zone provided above the latter, and / or rinsing with a powder cloud which is inflated by spray heads which are fixed or movable.

Further, it has been proposed that the immersion tank be provided with insulating inner surfaces to prevent premature discharge of the powder particles.

Requirement to use insulating material for

It reduces the possibility of using the above-described method from the immersion tank. In particular, it is a disadvantage that the submersible reservoirs for vortexing, which have metal inner and outer walls, cannot be additionally provided with electro-kinetic charging devices to be used for said process. In addition, there are both economic and manufacturing disadvantages in the production of electrically insulating submersible tanks. The low temperature resistance of most insulating substances does not allow heated workpieces to be introduced into the immersion tank. Furthermore, according to GDR pat. No. 113,289, which teaches the charging of powder particles directly in the ejector by electro-kinetic phenomena, wherein the charging device is to be located outside the immersion tank in order to ensure that there is no charge in it. -Dependent on workpiece and evenly distributed charge. With the arrangement of the electrokinetic charging device outside the submersible reservoir, there is a disadvantage of the long suction tubes for ejectors which are incorporated directly into the bottom of the filter, whereby uncontrolled frictional charging of the powder particles and consequently the uncontrolled charging of the powder particles can occur. to this, irregularities during transport 204127

Claims (2)

Powder and air dispersion. Incorporating the intake pipes directly into the bottom of the filter with manufacturing difficulties. It is an object of the present invention to avoid defects that still exist in the prior art in terms of manufacturing process, manufacturing technique and economics, while maintaining a continuous charging process that results in a homogeneous charge density in the immersion tank. SUMMARY OF THE INVENTION The object of the present invention is to provide a device for electrostatic powder deposition in a submersible container, in which submersible reservoirs of electrically conductive material can be used and powder circulation can be stabilized as well as the transport and regeneration of particle charges. The above-mentioned disadvantages are eliminated by the device for electrostatic coating of the workpiece with the powder according to the invention, the principle of which is that the ejector is provided inside the fuel tank and the opening of the ejek-torp suction pipe opens above the porous bottom plate in part of the submersible tank filled during operation. to the fluidized layer. With the aid of one or more such ejectors, the powder is kept in continuous circulation to form and regenerate the charge particles. According to a preferred embodiment of the invention, at least the inner surfaces of the immersion tank are made of an electrically conductive material and are connected to the earth potential. In such powder charging, the electrically conductive inner walls of the immersion tank do not have a negative effect on the constant and homogeneous charge density of the finely dispersed powder particles. Charging of powder particles with electro-kinetic charging devices and their discharging by electrostatic settling on grounded limiting surfaces of the tank and on grounded workpieces are in equilibrium with each other. Due to the arrangement of the charging orifices, which is optimal for the electrophysical processes, a higher and more stable powder charge is achieved, thereby achieving the same possibilities for use as well as grounded metal immersion containers. At the same time, the production of the coating device is simplified and becomes more economical. In particular, the invention allows additional equipment to be installed in the field of fluidized-bed charging by electrokinetic charging devices without much expense. The device according to the invention will now be explained with reference to the drawing. The drawing shows schematically a coating device in cross-section: According to the figure, powder 2 is fluidized in the fuel reservoir 1, preferably metal, through the transverse bottom plate 10 by a gas stream 11. Through the suction tube 3 leading into the fluidized layer 13, ejector 4, which is inside the immersion tank 1, the powder particles reach the mixing pipe 8, which is insulating material and in which they are intensively fluidized and gas-flowed 5 and receive an electrokinetic charge, which is still supported by the earthed metal tip 7. Thereafter, the electrically charged powder particles are conveyed back through the blowing sides 12 of the ejector 4 to the fluidized bed 13. Several electrodes may also be used to increase the charge of the powder and achieve a more uniform charge distribution in the powdered fluidized bed. The coating of the grounded workpieces8 is preferably carried out in the finely dispersed discharge zone 9 of the precursor. An apparatus for electrostatically coating a workpiece with a powder consisting of a submerged holder with at least one ejector, the mixing tube of which simultaneously forms an electro-electric charging device, the coating being carried out by immersing the workpiece in a powder cloud of electrically charged particles, characterized in that the ejector (4) is fixed inside the immersion tank (1) and the opening of the suction pipe (3) of the ejector (4) opens above the transverse bottom plate (10) into the part 1 of the submersible container (1) filled at fluidized bed (13). 2. Apparatus according to claim 1, characterized in that at least the inner surfaces of the immersion sleeve (1) are made of electrically conductive material and are connected to ground potential. 1 sheet of drawings SeveiOgraíiu, n. P., Race 7. Most