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    Home > Coatings News > Paints and Coatings Market > Analysis of the application of rectitte power supply for a car coating line.

    Analysis of the application of rectitte power supply for a car coating line.

    • Last Update: 2020-10-09
    • Source: Internet
    • Author: User
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    Analysis of the rectitive power supply application of a car coating line
    This article Yang Tianyu, Tang Fei, Jiang Qingtao, Dong Baohua, Wang Haitao
    Source: 2020 Paint Industry No. 6
    Author's Introduction
    Yang Tianyu (1986-): Male, engineer, staff of China Automotive Industry Engineering Co., Ltd., mainly engaged in the application of automotive coating line electrophoresis equipment.
    in the automotive coating industry, electrophoresis technology is widely used in body primer production lines, according to the body charge is different, divided into anode electrophoresis, cathode electrophoresis. At present, the most widely used is cathode electrophoresis, the contents described in this paper, are around cathode electrophoresis.
    power supply used in electrophoresis, neither water pumps, fan 380V AC power supply, nor the control system commonly used 24V DC power supply, but after special rectifier processing output of 0 to 400V or 0 to 500V DC power supply, called rectifier power supply.
    recting power supply has AC380V, AC10kV, according to different project requirements, the output voltage has DC0 to 400V or DC0 to 500V and other different specifications, the maximum current can be made in accordance with the requirements of 1000A, 1500A and other specifications. In engineering applications, the actual output voltage is generally in the range of 100 to 350V, and the peak current generally does not exceed 80% of the maximum current of the rectity supply.
    electrophoresis tank, many pieces of metal electrodes, i.e. anodes, are generally evenly distributed. The top of the anode is provided with a post connected to the positive side of the rectaling power supply via a cable. The body is connected to the negative pole of the rectifier by a sling and its copper brush, which is connected to the cathode copper row.
    electrophoresis time is generally 3 to 4min, in the continuous production line, the body will be within 3 to 4min, from the entrance of the electrophoresis tank to the exit, the body through the area will be divided into 2 to 3 areas, each area of voltage values are different. The division of different voltage regions can be achieved by dividing the anode or cathode, and the specific zoning scheme has a very important impact on the actual load of each rectition power supply.
    1 engineering case
    a car coating workshop using cathode electrophoresis process continuous production, as shown in Figure 1.
    1 System Figure
    the body passes through the electrophoresis slot from left to right, passing through three voltage partitions in one, two and three segments in turn. A total of 3 rectifiers, Figure 2 is the rectifier positive and negative wire diagram, the number of anodes is only indicative, not the exact value.
    2 Power-up system diagram
    basic information is as follows: (1) Mode of transmission: continuous transmission. (2) Power-up mode: three-stage voltage, cathode copper row segment, co-anode, full immersion after power-up. (3) Anodes: 26 side anodes in the first paragraph, 24 anodes on the side in the second paragraph, and anodes on the side in the third paragraph 24 on the side. Set 1 current meter per anode to display current values in real time. (4) Rectary power supply: a total of 3 rectary power supply, corresponding to 3 areas, in turn, low voltage zone, high voltage 1 zone, high voltage 2 zone, set 3 different voltages. The control cabinet touch screen displays the total current value of each rective power supply in real time.
    by recording, organizing and comparing the current data, the operating characteristics of the rectition power supply in cathode electrophoresis anode zoning mode can be derived.
    3 shows the voltage and current curves output by the three rectitive power supplies as the bike passes through the electrophoresis tank.
    the current value of each anode as the original data, the corresponding current curve is obtained according to 2 different rules, as shown in Figure 4 and Figure 5. Figure 4 Current curve data finishing rules are: when the copper brush touches any section of copper row, the current value of all anodes in the adulation tank, that is, the current curve of each cathode copper row, the short intersection of the curve is the transition of the copper brush between 2 sections of copper row. Figure 5 Current curve data consolidation rules are: according to the division of the anode region, respectively, add up the current value of the anode belonging to each segment, that is, the current curve of the anode partition.
    from the curve trend, numerical comparison, it is clear that Figure 4 and Figure 3 coincide. Explain that when the body is connected to a copper row, the current add-on value for all anodes is the total current of the rectation power supply there.The curves in the circle in Figure
    3 show the needle-like peaks and troughs, showing the voltage and current characteristics of the rectary power output when the copper brush transitions between high and low-voltage copper rows: the voltage of the low-voltage rectary power supply increases briefly, while the voltage of the high-voltage rective power supply decreases briefly. At the same time, the current value of the lower voltage rectation supply plummets to zero, while the current value of the higher voltage rectation supply surges. Explain that when the lifting copper brush transitions between 2 copper rows, 2 rectaling power supplies connected to 2 copper rows simultaneously apply voltage to the work piece on the lifting, while the current is output by the rectation power supply with a higher voltage value.Figure
    3 Measured rectary power output voltage, current curve (single vehicle)
    Figure 4 Single-vehicle current data finishing-1
    From Figure 5, it can be seen that the body in turn through the low-voltage zone, high-voltage 1 zone, high-voltage 2 zones, the beginning and end of the current in each region in turn, the current change trend is similar. As the body approaches an area, the current in that area increases, the body gradually distances from an area, and the current in that area decreases. The influence area of the anode is not the space occupied by the anode itself, but extends to a certain distance around it, the higher the voltage, the wider the range of influence.
    Figure 5 Single-vehicle current data consolidation-2
    For the convenience of data analysis, the data points of the curve end of the low-voltage zone in Figure 4, the end of the curve in the high-voltage zone 1 and the front current value of the high-voltage zone 2 are 0 are eliminated, and the trend line and formula of the current curve are shown in Figure 6 to Figure 8.
    6 Low Voltage Zone Current Curve
    Figure 7 High Voltage Zone 1 Current Curve
    calculated by Figure 6: Rectal Power Supply No. 1 outputs Q1, average current Im1 x 236 A. Peak current Imax1, 402 A, Imax1:Im1=1.7:1

    .
    8 High Voltage Zone Current Curve
    Total power Q-Q1-Q2-Q3-98458C, average current Im-362A.
    According to the design, the body in the electrophoresis tank full immersion time of 200s, the body into the tank after the full immersion began to power up, charged out of the slot, so, the graph can be seen, 200s rear body out of the slot process there is still current.
    only for the body full immersion of 200s range of current analysis, remove the body with electric outlet stage of the current data, recalculation of more than
    for the single-vehicle current data, according to the data consolidation rules of Figure 4 to obtain a graph and the actual operation curve of the rectregation power supply. In order to further verify the accuracy of Figure 4 data finishing rules, the bike experiment needs to be extended to the continuous vehicle experiment.
    continuous production, 3 voltage zones, low-voltage zone, high-voltage zone 1 copper row at the same time the maximum number of body is 1, therefore, low-voltage zone, high-voltage zone 1 of the single-vehicle current curve and continuous vehicle curve has a very high similarity, continuous vehicle curve presents periodic, each periodic curve unit is consistent with the single-vehicle curve. High-voltage 2 zone copper row at the same time appeared more body, for 3, therefore, high-voltage 2 zone continuous vehicle curve and single-vehicle curve between the difference is large, no obvious similarity, the need for 3 and above continuous body to simulate the full production of the load of the rectition power supply.
    9 shows that 4 cars pass through the electrophoresis tank continuously, and the output voltage and current curve of 3 rectitive power supplies respectively. Figure
    9 Measured rectified supply voltage, current curve (continuous overdring)
    Figure 10 shows that when the copper brush touches each section of the copper row, all anode-added current curves, the trend and value of which are consistent with the Figure 9 curve, thus further verifying the accuracy of the data consolidation rules.
    Fg. 10 Continuous Passing Current Curve
    As can be seen from Figure 10, the high-voltage 2-zone continuous over-vehicle curve has the same peak in 224s and 284s continuously, and has shown periodicity, reflecting the characteristics of the continuous over-vehicle curve, and the data in this range are separately collated, as shown in Figure 11. The calculation can be calculated: No. 3 rectation power supply output power Q3, the average current Im3, 915 A. Peak current Imax3 s 1340A, Imax3 s Im3 s 1.5:1.
    11 High Voltage Zone Current Curve
    Comparing high voltage 1 zone, high voltage 2 zone, peak current ratio Imax3:Imax2=1.8:1, average current ratio Im3:Im2=1.7:1. The peak current and average current differences of Rectifier No. 2 and Rectifier No. 3 are large, and there is room for further adjustment in the distribution of production load.
    2 Application Expansion
    During the above body electrophoresis process, the body resistance value increases with the gradual thickening of the paint film, so the voltage that needs to be applied increases gradually. In the slot segment, the body paint film is the thinnest stage in the whole process, in order to avoid the reaction too fast, resulting in paint film quality defects, the voltage of the slot segment is low, that is, the low voltage zone. The voltage in the high-voltage zone is higher and the current is higher.
    From figure 9 data, the high-voltage zone 2 current is the largest, its peak current is about 2 times the peak current of the high-voltage zone 1 zone, low-voltage zone peak current is 3 times, that is, the peak load of the No. 3 rectifier is 2 times the peak load of the No. 2 rectifier, 3 times the peak load of the No. 1 rectifier. The load of the three rectifiers varies greatly and is very uneven, resulting in a large installed capacity of the equipment as a whole, but the actual efficiency is low. Based on the above data consolidation and graph comparison results, we can adjust the cathode copper row segment position, that is, adjust the length ratio of each segment of copper row, to achieve the adjustment, balance the peak load of the rectation power supply, improve the efficiency of the purpose.
    At present, the power-up time of the low-voltage zone is about 48s, the production beat is 60s/station, taking into account the use of full immersion after power-up mode, high-voltage zone power-up time, film thickness and other factors, the length of the copper row in the low-pressure zone remains unchanged, extending the length of the copper row in the high-voltage zone 1 area, shortening the length of the copper row in the high-voltage zone 2 zone, that is, the copper discharge boundary line in the high-voltage zone 2 is shifted. That is, from the time definition, the high-pressure zone 1, zone 2 copper boundary to the direction of high-pressure zone 2 translation 10s.
    12 Single-vehicle current data simulation
    Figure 13 Continuous over-vehicle current data simulation
    Figure 12 is an analog bike through an electrophoresis tank, three rective power supplies output the current curve.
    13 shows the current curve of the simulated 4 cars passing through the electrophoresis tank and 3 rectitive power supplies. At this point, the peak load ratio of the No. 2 rectation power supply and the No. 3 rectation power supply is close to 1:1.
    12, the first and back segments of the high-voltage 1-zone current curve are very different, in order to ensure high accuracy, it is segmented to fit the trend line, as shown in Figure 14, the calculation can be Q2, the average current Im2, 578A. Peak current Imax2 s 1198A, Imax2 s Im2 s 2.1:1.
    14 High Voltage Zone 1 Current Curve
    Figure 15 shows the high voltage Zone 2 current curve and the fitted trend line, the calculation can be Q3, the average current Im3 is 842A. Peak current Imax3 s 1150A, Imax3:Im3 s 1.4:1
    compared to high voltage 1 zone, high voltage 2 zone, peak current ratio Imax3:Imax2 s 1:1, average current ratio Im3:Im2 s 1.5:1. The peak current ratio Imax3:Imax2=1.8:1 and the average current ratio Im3:Im2=1.7:1 were adjusted before the position of the cathode copper segment in the high-voltage zone 1 and the high-voltage zone 2. It can be seen that after adjusting the position of the copper row segment, the peak current and average current of the No. 2 rectifier and the No. 3 rectifier are close to each other, and the distribution of production load is more reasonable.
    3 Conclusion
    For cathode copper segmentation, electrophoresis line of the co-anode:
    (1) When the sling copper brush touches a section of copper row, the current value of the rective power supply connected to it is equal to the sum of all anode current values.
    (2) When the lifting copper brush transitions between 2 cathode copper rows, the total current of the adjacent 2 rectation power supplies will change dramatically, the rectation current value of the lower voltage drops to zero, and the rectation supply current value with a higher voltage rises sharply. That is, if two rective power supplies are powered on the same car at the same time, the current is actually output by the high voltage rective power supply.
    (3) by adjusting the position of the copper segmentation points, the production load of multiple rectition power supplies can be realloced, so that the peak current and average current of each rectition power supply are as close as possible. For built production lines, the safety factor of equipment operation can be improved, and for new production lines, the installed power can be reduced.
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