Main spraying parameters of industrial spraying 7-axis robot. The early spraying equipment consisted of a reciprocating machine and an automatic spray gun for simple spraying. With the rapid development of technology and the diversification of products, the simple reciprocating machine can no longer meet the requirements of different shapes and complex spraying processes. The industrial flexible robot spraying technology has become an indispensable and important link in the coating production line irreversibly.

(1) Coating efficiency, coating efficiency and coating effectiveness of spraying robot

Painting efficiency is the efficiency of spraying operation, including the effective utilization rate of spraying area, coating and spraying area per unit time. The coating efficiency is the ratio of the amount of paint applied on the coated object to the total amount of paint actually sprayed during the spraying process, or the ratio of the measured thick film on the coated object surface to the film thickness calculated from the amount of paint sprayed, that is, the transfer efficiency of the paint (TE for short) or the utilization rate of the paint.

Coating effectiveness refers to the ratio of the actual surface area of the sprayed object to the coverage area of the spray gun operation; In order to make the coating film at the edge break part of the coated object complete, the coverage area of the general spray gun operation shall be greater than the area of the coated object.

(2) Spray trajectory of spray robot

The spraying trajectory of the spraying robot refers to the sequence and travel of the spray gun during the spraying process. The spraying trajectory of skilled painters can be imitated by using the spraying robot.

(3) Paint flow rate of spraying robot

The paint flow rate of the spraying robot is the amount of paint delivered to each rotating cup per unit time, also called spraying flow rate and paint output rate.

In addition to the rotating speed of the rotating cup, the coating flow rate is the second factor affecting the fineness of atomized particles. When other parameters remain unchanged, the lower the paint flow rate, the finer the atomized particles will be, but it will also lead to the increase of solvent volatilization in the paint mist.

The high paint flow rate of the spraying robot will form a corrugated film. When the paint flow is too high to overload the rotating cup, the film on the edge of the rotating cup will thicken to a certain extent, resulting in the groove lines on the rotating cup can not make the paint diffluent, and layered paint skin will appear, which will produce bubbles or uneven size of paint drops.

The maximum paint flow rate of each spray gun of the spraying robot is related to the diameter of the high-speed rotating cup and the density of the paint at the rotating speed, and its upper limit is determined by the fineness of atomization and the effect of electrostatic coating. The practical experience shows that the paint should be input at a constant speed, and the fluctuation in a small range will not affect the film quality. The content of WeChat for metal processing is good and worth paying attention to.

In the actual spraying process, the coating flow rate of each rotating cup is different due to the different areas sprayed by the spraying robot. In addition, the coating flow rate of the rotating cup will also change due to the change of the shape of the coated object. Taking spraying the car body as an example, when spraying large areas such as door panels, the amount of paint ejected should be large; when spraying door pillars and window pillars, the amount of paint ejected should be small, and the amount of paint ejected should be automatically and accurately controlled during the spraying process, so as to ensure the uniformity of coating quality and film thickness, which is also one of the important measures to improve the utilization rate of paint.

(4) Rotating speed of rotating cup of spraying robot

The rotating speed of the spray robot rotating cup is the biggest factor affecting the atomization fineness of the rotating cup at high rotating speed. When other process parameters remain unchanged, the larger the rotating speed of the rotating cup is, the smaller the diameter of the paint drops is. In the range of slightly low speed, the influence of rotating speed on the atomization fineness is significantly greater than that in the range of high speed.

The rotating speed of the rotating cup of the spraying robot will affect the film thickness. When the rotating speed is too low, the coating film will be rough; Spraying robot and too fine atomization will lead to paint mist loss (causing overspray), which will make the film thickness fluctuate; Colleagues are very sensitive to any air flow in the paint booth when atomizing superfine. The high rotating speed of the rotating cup will not only cause overspray, but also lead to excessive wear of the turbine bearing, increase the consumption of compressed air for cleaning and reduce the solvent content in the coating film. The optimal rotating speed of the rotating cup of the spraying robot can be determined according to the flow rate characteristics of the coating used, so the rotating speed of the rotating cup of the water-based coating with surface tension and the two-component coating with high viscosity is higher than that of the ordinary solvent based coating.

In general, the rotating speed of the spraying robot's no-load rotating cup is 6X10 ^ 4r/min, and the speed range set under load is (1.0~4.2) X10 ^ 4r/min with an error of ± 500r/min

The electrostatic spraying technology has become the mainstream spraying technology in the automobile industry today, and the application of electrostatic automatic spraying equipment has made the middle and surface coating of automobiles enter the automation era. The main spraying parameters of the spraying robot are briefly described below.

1. Spray flow

The flow of the electrostatic spraying robot is the amount of paint delivered to the rotating cup per unit time, also known as the amount ejected. The flow rate affects the thickness of the paint film. The coating of different colors has different covering capacity and construction film thickness. During the spraying process, each robot plays a different role in the spraying area, and the flow set is also different. At the same time, the flow is also related to the shape of the sprayed object. For automobiles, the regular five door and one cover profile generally has a large flow, while the flow of columns, edges and corners is small.

2. Forming air

Gas is sprayed out from the evenly distributed holes at the back of the rotating cup to limit the amplitude of the paint mist (fan amplitude), push the atomized paint mist to the coated object, and place the paint mist to diffuse and rebound to pollute the rotating cup and atomizer. For metallic paint, the spray width will affect the final color effect, and it is easy to appear zebra stripes or hairiness if the spray width is not appropriate. The spray width setting is related to the distance between two guns, and the number of paint overlays is 3. If the distance between the two guns is 100mm, the spraying range should be better controlled to 300mm, so that the same point of paint can be stacked three times.

3. Rotating speed of rotating cup

The rotating speed of the rotating cup is the key parameter of paint atomization. The centrifugal force generated when the rotating cup rotates at high speed makes the paint atomization very thin (50-100 μ m). The smaller the diameter of the paint drop, the better the smoothness of the paint film, the smaller the orange peel effect, and the higher the gloss. The speed setting is also related to the type of paint. The speed of paint is relatively small, and the speed of intermediate paint and varnish is relatively high. The rotation speed is also related to the flow rate. When the flow rate is high, the rotation speed should also be increased to achieve a better atomization effect. However, if the rotation rate is too high, the paint sprayed on the coated object will be dry, which will lead to orange peel problems.

4. High pressure

In electrostatic spraying, the coated object is the positive pole and the rotating cup is the negative pole. High voltage is applied between the two poles to generate strong electric attraction, so that the atomized paint mist particles can be transmitted to the surface of the coated object. The size of high voltage affects the electrostatic effect of electrostatic spraying, painting rate and uniformity of paint film.

Flow, rotating speed, molding air and high pressure directly affect the film quality, and also affect the utilization rate of paint. In production, the paint characteristics and atomizer parameters should be combined to adjust. The four in one parameters should be comprehensively considered and continuously optimized to achieve the ideal spraying effect.

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