Daily management of cathode electrophoresis line o

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Daily management of car cathode electrophoresis line

in order to ensure the normal production and obtain stable coating quality, the electrophoretic coating production site must strictly and scientifically manage the equipment, tank solution and production environment, and make daily maintenance and operation records. Relevant parameters must be measured regularly and made into change curves to find rules, find problems in time and solve them. After most of the electrophoresis lines are completed, the actual effect basically fails to meet the design expectations, which ultimately affects the quality of the electrophoresis body and the normal operation of the whole line. Therefore, some equipment or processes should be improved in combination with the actual production to obtain better electrophoresis quality and expected results

the quality of electrophoretic paint film plays a very important role in the appearance of the whole vehicle paint film. A good appearance of electrophoretic paint film can not only reduce the working intensity of the next process, but also provide a good paint film foundation for the next process. With the increasingly obvious advantages of rodip-3 turnover conveying system in the electrophoresis line, major automobile manufacturers have introduced this system. Although the equipment, process and materials have a great impact on the quality of paint film, the coating management can not be ignored

electrophoretic tank solution management

cathodic electrophoretic tank solution management is the most important item in the process management of the electrophoretic line in the coating workshop. In order to ensure the stability of the bath solution and the stability of the coating quality of the car body paint film, technicians must detect the key parameters of each process of the electrophoresis line on time to monitor the change of the bath solution. Take the corresponding relationship between tank liquid composition, characteristic value and process conditions as an example, as shown in Table 1

the coating workshop of Chery company generally controls the stability of the bath solution by timely detecting the parameters of the electrophoresis system with the supplier every 4H to make it in the best range

through detection, technicians can timely understand the fluctuations of the parameters of each tank solution in the electrophoresis system, and timely add and adjust the tank solution to ensure the stability of the electrophoresis tank solution and the quality of the electrophoresis paint film

in addition to the timely testing and detection of the parameters of each tank solution of the electrophoresis system in the coating workshop every 4h, the test technology center of Chery company also carries out the necessary testing of the parameters of each tank solution of the electrophoresis system every day, in order to strengthen the management of the electrophoresis tank solution and ensure the stability of the electrophoresis paint tank solution

Chery electric VOC: volatile organic compounds swimming paint suppliers send electrophoretic paint samples to the headquarters laboratory every week for routine and unconventional testing items

in addition to the normal detection, it is also necessary to regularly measure the unconventional detection items of the tank solution, such as bacteria, heavy metal ion content, etc., to ensure the stability of the electrophoresis tank solution. Once any abnormality is found, it can be adjusted and handled in time

equipment management

as we all know, electrophoresis equipment plays a key role in the whole coating equipment. The normal operation of electrophoresis equipment is the basic guarantee for generating a good electrophoresis paint film. Electrophoresis equipment includes tank liquid circulation system, heat exchange system, filtration system, rectifier power supply, anode system, ultrafiltration system, etc. the management of electrophoresis equipment is the focus and difficulty of each electrophoresis line

1. Management and maintenance of ultrafiltration system

ultrafiltration has two purposes: to supply sufficient ultrafiltration and water-soluble impurities in purification paint for effective closed-circuit washing system, which can improve the utilization rate of electrophoretic paint. The key point of ultrafiltration system management is the ultrafiltration filtration volume. Technicians check and record the ultrafiltration system flow every day, and take corresponding measures to deal with abnormalities immediately. When the ultrafiltration excess decreases by 30%, it is necessary to organize and clean. The causes of low permeability are roughly divided into the following aspects:

□ low tank liquid flow in ultrafiltration equipment, changing the pressure setting, lack of coarse filtration, frequent stagnation of equipment (the equipment stops running for more than 1 hour) will reduce the permeability, and may even cause damage to the diaphragm (ultrafiltration membrane)

□ the temperature of the bath liquid is too high

□ ultrafiltration membrane activation layer failure: the activation layer converts the polarity of the charged material to the same polarity as the tank liquid itself. Its function is limited by time, and its durability can reach several months under the best conditions. After the activation layer fails, its function should be restored by cleaning. During cleaning, the cleaning solution should be prepared in strict accordance with the formula and proportion, and the cleaning procedure should be carefully followed, otherwise the ultrafiltration membrane will fail or be scrapped

2. Management and maintenance of edro system

the environmental protection design of the electrophoresis line in the second coating workshop of Chery company to achieve zero emission is due to the application of edro system, which turns ultrafiltration into pure water to spray the car body. The key point of its management is also the permeability of pure water. The reasons for low pure water are usually:

□ improper maintenance during shutdown: the correct method is to wash the reverse osmosis system with pure water once a day when the shutdown time is not more than 72h, and stop after 30min of operation, so as to prevent the components from losing water or growing microorganisms; If the shutdown time of the system exceeds 72h, it must be stored with chemicals

□ improper selection of cleaning agent and method: the correct method is to check the sediment at the water inlet end of the membrane element or the sediment on the filter element before cleaning, judge the nature of the blockage on the membrane surface, select the appropriate cleaning agent, and pay attention to the control of the pH value and temperature of the cleaning solution

□ the ultrafiltration is polluted or the pre filtration is insufficient, causing the bacteria or resin and other pollutants in the ultrafiltration to enter the reverse osmosis membrane

3. Management and maintenance of anode system

careful maintenance of anode and anode solution system is very important to the electrophoretic coating process. Always check the anode system and the growth of anode bacteria, otherwise the anode circulation circuit will be blocked. The conductivity probe in the anode bath liquid should be cleaned regularly. The conductivity of the anode liquid should be measured in the laboratory to calibrate the metering instrument of the anode system. Not all stainless steel anode materials can also prevent the corrosion of acid medium in the anode cover. Some stainless steel anode materials dissolve quickly in the anode cover. The technicians in the coating workshop cooperate with the electrophoretic material supplier to drain and clean the anode system every month, and then carry out sterilization and pure water circulation cleaning. For the advanced meters with anode flow entering the domestic new energy material industry, they should also be disassembled and cleaned regularly to prevent the rotor from being attached by bacteria corpses, which will reduce the flow, slow down the replacement, and affect the stability of the electrophoresis tank solution

4. Management and maintenance of liquid level gauge

due to the high viscosity of the electrophoretic paint, the installation place of the liquid level gauge is a dead corner of the electrophoretic paint cycle, so it is easy to be blocked. If it is not dredged and adjusted in time, it will affect the balance of the liquid level in the electrophoretic tank. Therefore, technicians should dredge and adjust the liquid level gauge of the electrophoresis system once a month to ensure the accuracy of the liquid level of the electrophoresis tank

5. Cleaning management of the drying room

every day during the shutdown interval, technicians will clean the inlet and outlet of the electrophoresis drying room. The key is to do a good job in the cleaning of the inlet elevator and the inlet and outlet roller beds. First, to prevent oil accumulation on the inlet elevator and the top of the drying room, causing oil dripping on the electrophoresis body; The second is to prevent the production from being affected by too much paint on the roller bed, which will cause the skid to be blocked or the roller bed belt to be broken. In the shutdown stage, technicians will deeply clean the whole drying room system. By cleaning the drying room, the oil dripping of the electrophoretic body can be reduced to less than 0.25%, and the number of electrophoretic line stops due to paint deposition is also decreasing month by month

6. Cleaning management of electrophoretic skid

due to the high viscosity of electrophoretic paint, it is easy to attach electrophoretic paint to the skid carrying the vehicle body. If the skid is not cleaned in time, the electrophoretic paint will be brought into the drying room, which will cause the accumulation and blockage of paint dripping on the roller bed and drive chain in the drying room, affecting the smooth progress of production. A scraper is set on the roller bed in the electrophoresis drying room to clean the paint accumulation at the bottom of the skid, and the skid is washed by offline high-pressure water gun regularly

process maintenance

the electrophoresis line in the second coating workshop of Chery company adopts the rodip-3 conveying system, which has many advantages, such as completely eliminating the bubbles in the front and rear covers and roof covers of the car body, uniformity of the electrophoresis paint film, improvement of the film thickness in the inner cavity of the car body, improvement of the washing quality after electrophoresis, improvement of the appearance of the electrophoresis paint film, reduction of tank fluid pollution, etc, However, no matter how good the equipment is, it cannot produce qualified car bodies without scientific and strict management. Chery's coating workshop II carries out the following special management according to the characteristics of rodip line:

□ during the shutdown of production shift conversion, the maintenance personnel should check the nozzle condition in each slot, dredge the nozzle that is blocked and can be removed, and replace the damaged one in time, If the spray direction of the nozzle is found to be bad, it should also be adjusted to ensure the best spray effect. In addition, the electrophoresis inlet and outlet and the electrophoresis channel wall plate should be cleaned to avoid dust and debris polluting the electrophoresis tank

□ during production, the equipment and process parameters of the electrophoresis line should be monitored, and the equipment operation should be recorded every 4H. If it is found that it is out of range, the reason should be found out in time for adjustment

□ control of bath solution process parameters: during the production process, technicians strictly monitor the parameters of electrophoresis bath solution, and cooperate with the electrophoresis supplier to test the parameters of electrophoresis bath solution every 4H to ensure the stability of electrophoresis bath solution

□ control of the quality of the pre-treatment phosphatized car body: the quality of the phosphatized film directly affects the electrophoretic paint film data. If the elongation exceeds 1000%, the stroke of 1000 can be selected or the output result: the output result of the experimental result can be arbitrarily set: the maximum force value, the quality of the elongation. Therefore, we should control the operation of the degreasing and phosphating slag removal system of pretreatment, the dredging of each spray nozzle and the spray volume of fresh pure water washing

□ control of drug addition: each shift should timely add drugs to the electrophoresis tank according to the parameters of the electrophoresis tank. When replenishing drugs, the replenishment acceleration must be controlled and closely tracked, and no evacuation is allowed

□ control of filter bag replacement: the electrophoresis adjuster should patrol the electrophoresis line at any time. If the pressure difference between the inlet and outlet of the electrophoresis filter exceeds the process specified value, it must be replaced in time. Generally, the filter bags of each circulation system of electrophoresis are replaced when production is stopped. If production is relatively compact, we generally choose to replace the filter bags of each circulation system of electrophoresis between meals. When replacing the filter bag, one of the keys is to deal with the electrophoretic paint in the filter, that is, air cannot be evacuated to enter the tank, and too much electrophoretic paint cannot be left to waste, which requires operators to have certain skills. The second key is to exhaust the filter after replacing the filter bag, and ensure that the filter is filled with electrophoretic paint before being incorporated into the system. This is also to ensure that air is not brought into the electrophoretic tank

□ control of electrophoresis drying temperature: test the room temperature curve of electrophoresis drying furnace every month. For different models, furnace temperatures before and during production, we have special personnel to track and test

□ in the holiday with a long time, it is necessary to organize to reverse the tank, focus on the inspection of the spray pipeline and nozzle of the tank liquid bottom spray and side spray, check the status of the spray pipe, nozzle and PVC pipe in the tank, and adjust the direction and angle of the nozzle on both sides of the tank bottom (as shown in Figures 1 and 2), so as to achieve the best condition when the tank liquid circulates

□ check the actual liquid level of the main and auxiliary tanks every hour, and control the electrophoresis main tank

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