SU927327A1 - Electrostatic spraying gun - Google Patents

Description

(54) ELECTROSTATIC GUN-SPRAYER

one

The invention relates to the field of surface finishing by spraying a paint and varnish material in an electrostatic field and can be used to finish, for example, wood.

A paint sprayer is known for spraying paints and varnishes in an electrostatic field 1.

It uses the electric field between the electrode to which the supply voltage is supplied from a low-power generator located in the handle and the liquid supplied for spraying and at zero potential to electrify the paintwork material.

A disadvantage of the known paint sprayer is the complexity of its manufacture with a low-power generator, located in the handle and with a visor to protect the insulator supporting the electrode from moist air, as well as the need for special equipment to drive the generator and power consumption.

Closest to the proposed technical essence and the achieved effect is an electrostatic spray gun, comprising a housing with liquid and gas nozzles and inducing an electrode sleeve with an outer layer of non-ferrous metal foil 2.

A disadvantage of the known nebulizer is a large fogging and insufficient adhesion properties of the aerosol produced due to the fact that it is equally charged. This requires a conductive coating to be applied to the surface to be treated.

The purpose of the invention is to reduce the fogging and increase the adhesion properties of the sprayed material by creating oppositely charged aerosols.

This is achieved by the fact that in an electrostatic spray gun comprising a housing with liquid and gas nozzles and an inducing sleeve electrode with an outer layer of non-ferrous metal foil, according to the invention, the sleeve electrode is made of a composite metal and electret half-rings separated by a dielectric gasket.

The drawing shows the output part of the pneumatic spray gun, the cut.

The output part includes a housing 1, along the axis of which liquid and gas nozzles 2 and 3 are mounted. The output section of the nozzle 2 coincides with the output section of the nozzle 3. A clamp KpbiujKa 4 of dielectric is mounted on the end of the housing 1. An inductive electrode-hub consisting of a metal half ring 5 and an electret half ring 6, separated by a dielectric (polyethylene) gasket 7 and an outer layer 8 of aluminum or copper foil, is placed tightly with the nozzle 3. The hole of the composite sleeve coincides with the hole in the pressure cap 4 of the dielectric. The annular cavity between the housing 1 and the nozzle 2 is connected to the fitting 9 of the compressed air supply. ,

The device works as follows.

At the same time, paintwork material is supplied through the nozzle 2 and compressed air is supplied through the nozzle 9 into the annular cavity between the body 1 and the nozzle 2. In the exit section of the nozzle 2, the paint material is sprayed with compressed air through the nozzle 3. The internal cavity of the composite sleeve, which is mounted flush with the nozzle 3, passes. The paint-and-paint material aerosol, which already has tribozard, is additionally electrified by forming oppositely charged aerosol when interacting with oppositely charged surfaces of the metal 5 and electret 6 parts of the sleeve, separated by a dielectric An outer layer 8 of the sleeve short-circuits the electret part 6 of the sleeve to the metal part 5. The clamping dielectric cover 4 keeps the composite sleeve in the housing 1. The device is based on the use of an electret effect - a polarized dielectric on its opposite sides carries different charges. dy The metal part of the sleeve is connected through the foil layer to the outside of the electret part and has a similar charge with it. The inner side of the electret part of the sleeve bears the charge of the opposite sign. In general, the composite sleeve is a capacitor, one lining of which is the metal part of the sleeve, and the other is the inner surface of the electret part of the sleeve. The integral sleeve creates an electrostatic field of considerable intensity in the output part of the spray gun: E 4x6ind.

Where

Zina

7G + 1

6 —effective surface charge density of the electret (for ceramic thermoelectric circuits 6

 105Cl / cm2); ind-surface charge density

induced on the metal

parts of the stump; B is the thickness of the sleeve; I is the inner diameter of the outlet of the sleeve;

 - dielectric constant of paintwork material. The electrostatic field created by the composite sleeve has a large heterogeneity due to its annular shape, and, as a result, has focusing

properties. The focusing action of the field and the electrostatic voltage between the oppositely charged drops of an aerosol of paintwork material make the spray more compact, the finish

The wood surface obtained with oppositely charged aerosols of the paintwork material does not require a pre-applied conductive coating to ground the part, since a double electric layer forms on the surface, which increases the paintwork's adhesion to the wood by 10-15%.

The use of the proposed electrostatic spray gun eliminates the need for electricity and electrical equipment, as well as frequent change of the sleeve due to electret loss of electrical properties, reduces the spray pattern when using the proposed device, reduces the loss of paint and varnish material for fogging by 5%.

Compared with the use of conventional electric and 10% conventional pneumatic spray guns, and also to reduce the total consumption of paint material almost 2 times due to the application of a more uniform and thin layer, to improve working conditions, due to a decrease in fogging. The application of the proposed device will allow to obtain an oppositely charged aerosol, due to which it is possible to increase the adhesion of the coating to the substrate by 10-15% and thereby improve the quality of the finish.

Claims (2)

1. USSR author's certificate number 113242, cl. B 05 B 5/00, 1957. 2. USSR author's certificate No. 643206, cl. B 05 B 5/02, 1977 (prototype).