The lighting industry is very developed in the Golden Triangle area of ​​Nanhai, Guangdong. Variety, good quality and high level of technology. The lamps and lanterns are fascinating, elegant and beautiful, and they form a variety of combination lamps. They are both beautiful and practical, and become an ornament that adorns the indoor environment, which greatly enriches people's material life. Most of these lamp ornaments are plated to obtain a beautiful appearance, and the surface is sealed by electrostatic spraying to achieve a decorative effect. 2 The color and surface requirements of the plated parts 2.1 Plating and color SPAN> Industrial plating is galvanized, followed by copper, tin, nickel, chrome, etc., with a single surface color. The lamp jewelry is plated with different plating types, and processed from the process to obtain different color effects, so the process is complicated. Common imitation gold, imitation 24K gold, green gold, new green gold, bronze, red ancient, red copper sand, green ancient, antique, brown bronze, light nickel, nickel, gold, pearl black, light nickel brown , Huang Qinggu, Titanium, sand nickel, nickel chrome, chrome sand, pearl silver, rose gold, green black, light chrome silver, silver, gold, green patina, hunters and so on. 2.2 Requirements for the surface of the plated parts 1 The surface of the plated surface should be smooth and flat, the film thickness is uniform, and there is no burr; 2 The color is bright and consistent, the color is clear, and the brightness is good; 3 The surface of the plated layer is water-free, British, sticky, oily, waxy, etc.; Strong adhesion, no shedding, cracks, pitting, etc.; 5 The surface hardness of the coating is good, up to 4H, good wear resistance and corrosion resistance. 3 Coatings and its sealing process 3.l Commonly used coatings In the spraying of lamp ornaments, the electrostatic spraying method is mainly used, and the varnish is used to cover the light to achieve the sealing effect. There are two types of varnishes, self-drying and drying, usually varnishes such as amino, acrylic and alkyd. (1) Acrylic amino varnish (2) Amino polyester varnish 3.2 Sealing process The so-called sealing method is to spray a layer of paint film on the surface of the plated part or dip a layer of paint film, one is to protect and extend its service life; Is to improve the decorative performance of the product. The process is as follows: (1) The plated parts are transferred to the closed production line → hanging up → soot blowing → electrostatic spraying (mechanized spraying and manual spraying) → drying → cooling → unloading → inspection (non-conforming product return plating) → packaging (Finished product) (2) Imitation gold plating parts → dewaxing → water washing → drying → dip 24K gold (prepared by gold plastic) → drying → unloading → inspection (non-qualified product re-soaking gold) → electrostatic spraying → drying →Cooling→Inspection (non-conforming product return plating)→Packaging (finished product) 4 Electrostatic spraying 4.l Basic characteristics of electrostatic spraying Electrostatic spraying mainly uses the principle of “corona discharge†generated by high-voltage electrostatic field, and the coating particles are in the electrostatic spraying process. The motion in the middle is generated by the electric field and is usually expressed by the formula: F=Eq where: F—the electric field force to which the paint particles are subjected; E—the electric field strength; q—the charge amount of the paint particles. At the same time, E is proportional to the voltage between the two poles, and inversely proportional to the distance between the two poles. It can be expressed by E=V/S. Where: V—static voltage applied to the gun and the part; S—the distance between the gun and the part. The larger E is, the larger the electric field force that the paint particles are subjected to. Electrostatic spraying has high production capacity, can be mechanized, automated, and continuous production. The utilization rate of coatings is as high as 80% to 90%, the paint film is uniform, the adhesion is good, the pollution is small, and the working conditions are good; but the disadvantage is equipment investment. Large, the adsorption of complex workpieces is not good, high-voltage electricity is easy to produce sparks, you must pay attention to safety. 4.2 Main equipment (1) High-voltage electrostatic generator; (2) Electrostatic spray booth; (3) Catenary automatic production line; (4) Electrostatic spray gun, including the following three categories: ◠Portable electrostatic spray gun is mainly composed of gas path, circuit, The oil circuit consists of three parts, which are usually used for replenishing small and medium-sized workpieces with complex shapes. ◠Ω disc type electrostatic spray gun Ω disc type electrostatic spray gun has a circular cylindrical shape, the top is equipped with a device that can reciprocate up and down, the lower part is equipped with a disc-type rotating spray plate, and the workpiece runs through the Ω-type catenary orbit into the drying room for spraying. . The disc type paint tray has a diameter of 200 to 625 mm and a rotational speed of 900 r/min. The oil delivery is 175-500mL/min. The rotating shaft rotates at a speed of 20 000 to 30 000 r/min and moves up and down. ◠Rotary electrostatic spray gun Rotary electrostatic spray gun is widely used in China. It has fixed type and pass type 2, mainly composed of oil supply device, high pressure generator, atomizer and transportation device. The diameter of the rotating cup is 60mm. And 75mm, the rotation speed is 2790 ~ 2800r / min, the oil delivery is 20 ~ 180mL / min. The structure of the rotating cup determines the effect of electrostatic spraying. Generally speaking, the larger the radius of curvature of the charged conductor, the greater the distribution density of the charge. Therefore, these factors should be considered when designing the rotating cup. 5 Electrostatic spraying process control (1) voltage
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