Since the electrification status of the powder coating from the friction Spray Gun directly affects the quality of the coating film on the workpiece and the deposition efficiency of the powder, it is required that the powder from the friction Spray Gun has good electrification performance and uniform powder mist delivery. Therefore, in order to increase the powder charging effect of the friction Spray Gun, equipment such as powder supply, powder delivery and Spray Gun should be equipped with corresponding charging measures, so that the powder particles sprayed from the gun mouth can be fully charged.
In order to ensure sufficient friction for powder coatings, sufficient powder supply air pressure is required. Among them, the gas supply pressure of the fluidized bed should be 0.02MPa, the primary powder supply pressure should be 0.1~0.22MPa, and the secondary powder supply pressure should be 0.01~0.05MPa.
Since the friction channel for the powder coating in the friction Spray Gun is narrow and the pipe diameter is about 1mm, in order to better generate friction, the particle size of the charged powder coating should not only be uniform and fine, but also have some specific requirements, such as:
①Easy to triboelectrification, powder coatings with better frictional electrification effects such as epoxy and polyxie modified epoxy should be used.
②It has a high degree of cleanliness and is strictly sieved to remove impurities such as fibers and hard particles to prevent them from blocking the nozzle of the Spray Gun.
③The powder should be dry. Humid agglomeration of powder coatings or ambient air humidity will significantly affect the electrification effect and powder deposition efficiency during friction. When the air humidity is low and the powder is dry, the chargeability of the powder will be better and the coating effect will be better; on the contrary, when the water content is high and the air humidity is high, the resistivity of the powder will decrease, and the charged charge will easily dissipate, which will affect the static electricity. adsorption effect. Therefore, the powder should be dried to remove moisture and prevent moisture. When the air humidity is high, the powder spraying amount should be increased by increasing the powder spraying air pressure to meet the spraying requirements.
④Compressed air needs to be purified. In order to prevent the adverse effects of moisture, oil and dust in the compressed air on friction spraying, the air from the Air Compressor must be fully purified, and its purification degree is better than that used in high-voltage electrostatic spraying. Air is higher.
⑤ The amount of powder spraying should be appropriate, because the spraying effect will be affected if the amount of powder spraying exceeds a certain range, so the appropriate powder spraying amount should be selected according to the requirements of different workpieces. For example, when spraying flat workpieces, the powder spraying amount is 80~100g/min When spraying the inner wall of the pipeline, it can be increased to 100~250g/min.
⑥ The spraying distance should be appropriate. The distance of friction electrostatic spraying is not as strict as the control of high-voltage electrostatic spraying, but has certain flexibility. As long as the control is proper, good spraying effect can be obtained. Generally, the shortest distance is not less than 50mm, and the farthest distance is not more than 300mm.
⑦ deposition efficiency. Generally, the deposition efficiency of friction electrostatic spraying is less than 60%. If frictional electrostatic heating spraying is used, the deposition efficiency can be increased to 80%~85%, and the thickness of the coating can be increased and the uniformity of the coating can be improved. Therefore, when it is necessary to obtain high When improving the deposition efficiency, heating tribostatic spraying can be considered.
冯文;李正超;向旭东 - 《东方汽轮机》