SU939109A1 - Apparatus for deposition of polymeric powder paints - Google Patents

Description

(54) DEVICE FOR DUSTING POLYMER POWDER PAINTS

one

The invention relates to a technique for spraying triboelectric charged polymer powder paints and may find its primary use for applying protective decorative coatings in the automotive, electrical and other industrial fields.

A device for spraying polymeric powder paints is known, comprising a spraying chamber, sprays, ejectors, pipelines for transporting and triboelectric charging.

In this device, the powder paint is electrostatically charged due to the friction of the powder-air mixture during transportation through pipelines against the walls and is deposited on a grounded product. Powder paint is applied by ejection 1.

The disadvantage of such a device is that during the process of operation (operation) the powder acquired by the particles due to the friction against the walls of the pipeline, the electric charge through the walls of the dielectric begins to flow, discharging on the surface of the nearby grounded objects through

air moisture. This leads to the fact that the amount of electric charge acquired by the powder at the outlet of the sprayer is reduced by 30-40 / o. Minimum charge leakage process (approx. -3-5 / o)

 at the beginning of the pipelines and begins to gradually increase, reaching 30–40% at the end of the pipelines, which leads to the fact that unpainted places may form on the parts or the thickness of the powder layer will be insufficient.

The purpose of the invention is to improve the quality of the coating by reducing the charge leakage from the surface of the pipelines.

This goal is achieved in that in a device for spraying polymeric powder paints containing a spraying chamber, sprays, ejectors and pipelines for transporting and triboelectric powder charging, the last 20 are equipped with sectional chambers of toroidal cross-section covering the pipelines along their entire length.

FIG. 1 shows a device for spraying polymeric powder paints.

general form; in fig. 2 shows section A-A in FIG. I.

The device (Fig. 1) consists of a sputtering chamber 1, a container 2 for fluidizing the powder, ejectors 3, nozzles 4 and pipelines for transporting n-triboelectric charging of the powder, each of which (Fig. 2) consists of an internal transport pipeline 5 of fluoroplastic, through which the powder-air mixture 6 is transported. The cooling chamber of the toroidal section consists of three autonomous sections 7, 8 and 9 (Fig. 1) and is formed by the outer wall of the pipeline 5 and. outer pipe 10 of fluoroplastic, between which refrigerant 11 is introduced, for example freon. The front side of the pipeline 10, metallized with aluminum film 12, the outer surface of which is covered with a heat insulating layer 13 of polyurethane foam is thicker, another 5-8 mm. The aluminum film has a satisfactory adhesion to both the fluoroplastic and polyurethane foam.

The device also contains a vehicle 14, a suspension bracket 15 with an article 16 and nozzles 17 for supplying a refrigerant.

The device works as follows. By means of the vehicle 14 on the suspension 15, the product 16 (motorcycle brake lever) enters the spraying chamber 1. In the fluidization tank 2, the powder paint is suspended. Compressed air pressure of 0.5 atm. is fed to the ejectors 3. The powder particles are entrained in the air, and the powder-air mixture 6 enters the inner transport pipe 5, made of fluoroplastic. In the cooling chamber of a toroidal section, through pipes 15, a refrigerant, such as freon, is supplied from a refrigerating machine (not shown). Due to the fact that the leakage of charges increases along the length of the pipeline, i.e. it is minimal at the beginning of the pipeline and maximal at the end, the refrigerant is supplied to the first section 8 of the refrigerating chamber with a temperature of (-8) - (- 10 ) C, in the second 9 - (-13) - (- 15) ° С, in the third 10- (-18) - (- 25) ° С.

Passing through the cooled PTFE line 5 and acquiring an electric charge due to friction against the walls of the dielectric, the powder is sprayed with sprays 4 and deposited on a grounded product 16. After this product enters the reflow oven (not shown) where it is formed (melted) coating and acquires the required physical and chemical indicators.

The use of a toroidal section refrigerating chamber for cooling the fluoroplastic pipeline increases the charge potential of powder paint particles to 28–30 kV as compared to 18–22 kV in the known device, and the charge leakage is completely eliminated due to a sharp decrease in the electrical conductivity of the material. A reduction in charge leakage allows one to obtain coatings of better quality, with a greater thickness than the known device, namely, 160–200 µm versus 120-170 µm, and in a shorter period, namely 7-8 sec. Against 10-15 c in a known device, and the execution of the sectional refrigeration chamber allows the temperature of the refrigerant to be controlled along the length of the pipelines, which makes it possible to increase the efficiency of the refrigeration compartment.

Claims (1)

Apparatus of the Invention A device for spraying polymeric powder paints comprising a chamber 0 papilines, sprayers, ejectors and pipelines for transporting and triboelectric powder charging, characterized in that, in order to improve the quality of the coating by reducing the charge leakage from the surface of the pipelines, the latter are equipped with toroidal sectional chambers covering the pipelines their entire length. Sources of information taken into account in the examination 0 1. Logunenkov V. A., et al. Introduction of a semi-automatic line for painting the hulls of wheel supports with polyvinyl butyral paint PVL-212 .- “Paintwork materials and their use, 1980, No. 5, p. 47-48 (about, totype). Yu / "