Film thickness estimation system for electrodeposition painting equipment

Abstract

To provide a film thickness estimation system for an electrodeposition facility, capable of controlling the thickness of a coating film formed on the surface of a car body within an intended thickness range and of reducing the loss of electrodeposition paint, by adjusting factors relating to the thickness of the coating film without delay.SOLUTION: A film thickness estimation system 1 according to the present invention is a system of estimating the thickness of a film of electrodeposition paint P1 present on each area of a car body W1, in an electrodeposition facility 10. The film thickness estimation system 1 comprises a learning unit 55, a storage unit 54 and an estimation unit 56. The learning unit 55 performs learning by associating data relating to the composition condition factor of the electrodeposition paint P1, data relating to the film thickness, and data relating to the adjustment factor of the electrodeposition facility 10 with each other. The storage unit 54 stores the data associated by the learning unit 55 as learnt data. The estimation unit 56 estimates the thickness of the film present on each area of the car body W1 according to the learnt data.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a film thickness estimation system for estimating the film thickness of an electrodeposition paint for each part of a vehicle body in an electrodeposition painting facility. [Background technology]

[0002] Conventionally, there has been known an electrodeposition coating equipment that performs electrodeposition coating on a vehicle body by applying a current from multiple electrodes arranged in an electrodeposition tank to the vehicle body immersed in an electrodeposition paint in the electrodeposition tank (see, for example, Patent Document 1). Electrodeposition coating using such electrodeposition coating equipment is widely used in the undercoat process of vehicle body painting for the purpose of imparting rust prevention performance. However, in electrodeposition coating, an excessive voltage is applied to ensure a film thickness on the interior plate part of the vehicle body, which results in energy and paint losses and excess film thickness. For this reason, various methods have been devised for controlling the thickness of the paint film formed on the surface of the vehicle body to a desired range.

[0003] In addition, factors related to the thickness of the coating film include, for example, the current passing conditions of the electrodes, the composition of the electrodeposition paint (bath liquid), etc. Data related to these factors are usually obtained through the operations shown in FIG. 6, and are recorded and managed in a document 100 (paper). Specifically, first, a monitoring operation is performed to individually monitor each factor (for example, the acid concentration of the electrodeposition paint 102 in the electrodeposition tank 101, the current value of the current applied to the vehicle body 104 from the electrode 103 arranged in the electrodeposition tank 101, etc.). Next, a comparison operation is performed to measure the film thickness of the vehicle body 104 that has been taken out of the electrodeposition tank 101 and then dried in a drying furnace (not shown), using a film thickness meter 105, and to compare the measured film thickness with each factor. In addition, data relating each factor to the film thickness is recorded in the document 100 as past data. After that, the monitoring operation and comparison operation are repeated many times, and each factor is adjusted by trial and error based on the past data. In this way, the coating film can be brought close to the target thickness range. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2020-132903 A (Figs. 1, 4, etc.) Summary of the Invention [Problem to be solved by the invention]

[0005] Incidentally, as described above, data on the film thickness and each factor are managed by recording them as past data in the form 100. However, the intervals at which the data is acquired are not constant, being every day or every few days. Moreover, since there are many types of factors, the factors to be adjusted must be determined by trial and error, and determining the factors takes time.

[0006] In order to solve the above problem, the invention described in claim 1 is a system for estimating a film thickness of an electrodeposition paint for each part of a vehicle body in an electrodeposition coating facility including an electrodeposition tank for storing electrodeposition paint and transporting a vehicle body while immersed in the electrodeposition paint, a plurality of electrodes arranged in the electrodeposition tank, and a transport means for transporting the vehicle body, the system including a learning unit that learns by associating data on composition condition factors of the electrodeposition paint, data on the film thickness, and data on adjustment factors of the electrodeposition coating facility, a memory unit that stores the data associated by the learning unit as learned data, and an estimation unit that estimates the film thickness for each part of the vehicle body based on the learned data. The adjustment factor of the electrodeposition coating equipment includes a current value of a current applied to the vehicle body, and the learning unit performs a missing value interpolation process to interpolate a missing value between the currently obtained data on the film thickness and the previously obtained data on the film thickness each time the film thickness data is newly obtained, and a current abnormal value removal process to determine a current value outside the certain range as an abnormal value and remove it from the learning data when the current value included in the data on the adjustment factor of the electrodeposition coating equipment is outside a certain range, and the estimation unit estimates the film thickness for each part of the vehicle body based on the learned data after the missing value interpolation process and the current abnormal value removal process have been performed. The gist of the present invention is a film thickness estimation system for electrodeposition coating equipment.

[0007] The present invention has been made in consideration of the above-mentioned problems, and its object is to provide a film thickness estimation system for electrodeposition coating equipment that can adjust factors related to the thickness of the coating film without delay, thereby making it possible to control the thickness of the coating film formed on the surface of a vehicle body to a targeted thickness range and reducing loss of electrodeposition paint. [Means for solving the problem]

[0008] In order to solve the above problem, the invention described in claim 1 is a system for estimating the film thickness of an electrodeposition paint for each part of a vehicle body in an electrodeposition coating equipment comprising an electrodeposition tank for storing electrodeposition paint and in which a vehicle body is transported while immersed in the electrodeposition paint, a plurality of electrodes arranged in the electrodeposition tank, and a transport means for transporting the vehicle body, the system comprising a learning unit that learns by associating data on composition condition factors of the electrodeposition paint, data on the film thickness, and data on adjustment factors of the electrodeposition coating equipment, a memory unit that stores the data associated by the learning unit as learned data, and an estimation unit that estimates the film thickness for each part of the vehicle body based on the learned data.

[0009] In the invention described in claim 1, the learning unit learns data on composition condition factors of the electrodeposition paint, data on film thickness, and data on adjustment factors of the electrodeposition painting equipment by associating them, and the estimation unit estimates the film thickness for each part of the vehicle body based on the data associated by the learning unit (learned data). In this case, since the film thickness can be estimated with almost no time delay after the data is associated, it is possible to prevent the composition of the electrodeposition paint from changing significantly before the film thickness is estimated. As a result, even if the composition of the electrodeposition paint changes over time, the coating film formed on the surface of the vehicle body can be kept within the desired thickness range, thereby improving the paint quality of the vehicle body. Moreover, since it is not necessary to put more electrodeposition paint into the electrodeposition tank in anticipation of changes in the composition of the electrodeposition paint, it is possible to reduce the loss of the electrodeposition paint.

[0010] Examples of the electrodeposition paint include cationic electrodeposition paint and anionic electrodeposition paint, but from the viewpoint of rust prevention, it is preferable to use cationic electrodeposition paint.

[0011] In addition, the compositional condition factor of the electrodeposition paint is preferably at least one selected from the acid concentration (MEQ), NV (non-volatile content), ash content, paint conductivity, and Coulombic efficiency (claim 2), and is particularly preferably the acid concentration. This is because the inventors of the present application conducted intensive research and confirmed that, among the compositional condition factors of the electrodeposition paint, the acid concentration in particular has a high correlation with the thickness of the coating film. However, since the acid concentration cannot be measured in real time, the inventors of the present application searched for a parameter that is linked to the acid concentration and can be measured in real time, and newly confirmed that the current value of the current applied to the vehicle body is linked to the acid concentration. From this, the acid concentration of the electrodeposition paint and, in turn, the thickness of the coating film can be estimated by measuring the fluctuations in the current value.

[0012] In addition, the adjustment factor for the electrodeposition coating equipment is the current value applied to the vehicle body. and , liquid temperature of electrocoating paint and At least one selected from the electrode current application time and It is preferable that (Claim 3). Effect of the Invention

[0013] As described above in detail, according to the inventions described in claims 1 to 3, by promptly adjusting factors related to the thickness of the coating film, the coating film formed on the surface of the vehicle body can be adjusted to a targeted thickness range and loss of electrocoating paint can be reduced. [Brief description of the drawings]

[0014] [Figure 1] FIG. 1 is a schematic cross-sectional view showing an electrodeposition coating facility according to an embodiment of the present invention. [Diagram 2] FIG. 4 is an explanatory diagram showing a method for adjusting a film thickness. [Diagram 3] Graph showing changes in acid concentration (MEQ) and current value. [Figure 4] A table showing management data. [Diagram 5] A graph showing how missing values ​​are interpolated. [Figure 6] FIG. 1 is an explanatory diagram showing a method for adjusting a film thickness in a conventional technique. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will now be described in detail with reference to the drawings.

[0016] As shown in FIG. 1, the film thickness estimation system 1 of this embodiment is a system that estimates the film thickness of an electrodeposition paint P1 for each part of a vehicle body W1 (for example, an outer door panel part, an inner door panel part, etc.) in an electrodeposition coating facility 10. The electrodeposition coating facility 10 is equipped with an electrodeposition tank 11 that stores the electrodeposition paint P1. In the electrodeposition tank 11, the vehicle body W1 is transported while immersed in the electrodeposition paint P1. The electrodeposition tank 11 is composed of a tank upper part 12 that constitutes the ceiling part of the electrodeposition tank 11, a tank bottom part 13 that constitutes the floor part of the electrodeposition tank 11, and two side walls 14. In addition, the electrodeposition tank 11 is opened with an entrance 15 for carrying the vehicle body W1 into the electrodeposition tank 11 and an exit 16 for carrying the vehicle body W1 out of the electrodeposition tank 11. The electrodeposition paint P1 of this embodiment is, for example, a paint that uses a cationic electrolytic resin as the main vehicle.

[0017] The electrodeposition coating equipment 10 also includes a conveyor 21 (conveying means) that conveys the vehicle body W1 in a conveying direction (rightward in FIG. 1). The conveyor 21 lowers the vehicle body W1 while carrying it into the electrodeposition tank 11 through the carry-in entrance 15, and lifts the vehicle body W1 while carrying it out of the electrodeposition tank 11 through the carry-out exit 16. The conveyor 21 includes a rail 22 that extends in the conveying direction, and a plurality of hanger rails 23 that are provided on the rail 22 and that suspend and carry the vehicle body W1. Each hanger rail 23 is further provided with a pulse transmitter 24 that periodically transmits a pulse signal.

[0018] As shown in FIG. 1, a plurality of electrodes 31 are arranged in the electrodeposition tank 11. Each electrode 31 is composed of side electrodes 32, 33 installed on the side wall 14 of the electrodeposition tank 11 and a bottom electrode 34 installed on the tank bottom 13 of the electrodeposition tank 11. The side electrode 32 is in the form of a strip extending in the vertical direction and is arranged at intervals along the conveying direction of the vehicle body W1. The side electrode 33 and the bottom electrode 34 are also in the form of a strip extending in the conveying direction and are arranged at intervals along the conveying direction. A cable 35 (see FIG. 2) is connected to each electrode 31. Each cable 35 is drawn out of the electrodeposition tank 11.

[0019] As shown in FIG. 2, the electrodeposition coating equipment 10 further includes an additive adding means 41 and a liquid component reducing means 44. The additive adding means 41 is for adding an additive 42 to the electrodeposition paint P1. The additive 42 in this embodiment is an organic acid such as citric acid, ascorbic acid, or tartaric acid. The additive adding means 41 includes a tank (not shown), an additive supply valve (not shown), and an additive supply nozzle 43 installed on an additive supply pipe (not shown) that communicates with the electrodeposition tank 11. The tank is adapted to send out the additive 42. The additive supply valve is disposed downstream of the tank and is adapted to switch the additive supply pipe to an open or closed state. When the additive supply valve is switched to an open state, the additive supply valve is adapted to supply the additive 42 sent out from the tank into the electrodeposition tank 11. The additive supply nozzle 43 is disposed above the electrodeposition tank 11 and is adapted to supply the additive 42 into the electrodeposition tank 11.

[0020] As shown in FIG. 2, the liquid component reduction means 44 is for reducing the liquid component of the electrodeposition paint P1. The liquid component reduction means 44 is configured by installing an electrodeposition paint outlet 46, an electrodeposition paint outlet valve 47, a filter 48, and an electrodeposition paint supply port 49 on a circulation pipe 45 whose both ends communicate with the inside of the electrodeposition tank 11. The electrodeposition paint outlet 46 is disposed at the tank bottom 13 of the electrodeposition tank 11, and is configured to discharge the electrodeposition paint P1 to the outside of the electrodeposition tank 11. The electrodeposition paint outlet valve 47 is disposed downstream of the electrodeposition paint outlet 46, and is configured to switch the circulation pipe 45 to an open state or a closed state. The electrodeposition paint outlet valve 47 is configured to be able to discharge the electrodeposition paint P1 to the outside of the electrodeposition tank 11 when switched to an open state. The filter 48 is disposed downstream of the electrodeposition paint outlet valve 47, and is equipped with a filter that separates the filtrate from the electrodeposition paint P1. The filter in this embodiment is a UF (ultrafiltration membrane) membrane. Furthermore, the liquid component of the electrodeposition paint P1 is reduced by the separation of the filtrate, and the filtrate separated from the electrodeposition paint P1 is discarded. The electrodeposition paint supply port 49 is disposed downstream of the filtration device 48, and supplies the electrodeposition paint P1 from which the filtrate has been separated into the electrodeposition tank 11.

[0021] Next, the electrical configuration of the electrodeposition coating equipment 10 will be described.

[0022] As shown in FIG. 1, the electrodeposition coating equipment 10 includes a personal computer 50, which includes a control device 51 for controlling the entire equipment. The control device 51 includes a CPU 52, a ROM 53, a RAM 54, an input / output circuit, and the like. The CPU 52 functions as a learning unit 55 and an estimation unit 56. The CPU 52 is electrically connected to a keyboard 57 of the personal computer 50 and a display 58 of the personal computer 50. The CPU 52 is electrically connected to the conveyor 21, each pulse generator 24, an additive supply valve, and an electrodeposition paint discharge valve 47, and controls them by various drive signals. In this embodiment, each electrode 31 is electrically connected to the CPU 52 by connecting the electrodes 31 to the control device 51 via a cable 35. The pulse signals output from each pulse generator 24 are periodically input to the CPU 52. The ROM 53 is also set (stored) in advance with production takt time information indicating the working time of the electrodeposition coating of each vehicle body W1. The ROM 53 also stores, for each of the side electrodes 32, electrode distance information indicating the distance from a reference position S1 located near the entrance 15 of the electrodeposition tank 11 to the side electrode 32.

[0023] Next, the electrodeposition coating method using the electrodeposition coating equipment 10 will be described.

[0024] First, the CPU 52 outputs a drive signal to the conveyor 21, causing the vehicle bodies W1 (hanger rails 23) to be continuously carried into the electrodeposition tank 11 through the carry-in entrance 15, and the vehicle bodies W1 to be continuously carried out of the electrodeposition tank 11 through the carry-out exit 16. Then, when the vehicle bodies W1 carried into the electrodeposition tank 11 are immersed in the electrodeposition paint P1, a current is applied to the vehicle body W1 from each electrode 31 arranged in the electrodeposition tank 11, and electrodeposition coating is performed on the vehicle body W1. As a result, a coating film is formed on the surface of the vehicle body W1.

[0025] If the coating film is within the targeted thickness range, electrodeposition coating continues without any adjustment work. However, since the composition of the electrodeposition paint P1 changes over time, continuing electrodeposition coating may cause the coating film thickness to fluctuate and deviate from the targeted thickness range. For this reason, the CPU 52 performs a process to estimate the coating thickness of the electrodeposition paint P1 for each part of the vehicle body W1. The coating thickness is estimated periodically (every day in this embodiment).

[0026] Specifically, the CPU 52 first calculates the current positions of the multiple (here, six) vehicle bodies W1 immersed in the electrodeposition paint P1. More specifically, the CPU 52 acquires production takt time information stored in the ROM 53. The CPU 52 also counts the number of pulse signals (number of pulses) output from the corresponding pulse transmitter 24 while the vehicle body W1 (hanger rail 23) moves from the reference position S1 (see FIG. 1) to the current position. The pulse count is performed for all vehicle bodies W1 immersed in the electrodeposition paint P1. The CPU 52 then calculates the moving distance of each vehicle body W1 from the reference position S1, i.e., the current position of each vehicle body W1, based on the counted number of pulses. Furthermore, the CPU 52 calculates the residence time of each vehicle body W1 in the electrodeposition bath 11 (time immersed in the electrodeposition paint P1) based on the current position of each vehicle body W1.

[0027] Next, the CPU 52 measures (monitors) the current value of the current applied from the electrode 31 (side electrode 32) to each vehicle body W1 (see FIG. 2). Specifically, the CPU 52 selects one vehicle body W1 from the multiple vehicle bodies W1 immersed in the electrocoating paint P1. Next, the CPU 52 selects, from the multiple electrode distance information stored in the ROM 53, the electrode distance information in which the distance from the reference position S1 to the side electrode 32 is the closest to the moving distance of the selected vehicle body W1. Then, the CPU 52 outputs a drive signal to an ammeter (not shown) and measures the current value of the current applied from the side electrode 32 to the vehicle body W1 corresponding to the selected electrode distance information. Thereafter, the measurement of the current value is performed in the same manner for the other vehicle bodies W1 immersed in the electrocoating paint P1. Note that data on the current value is stored in the RAM 54 for each vehicle body W1.

[0028] The CPU 52 also estimates (monitors) the acid concentration (MEQ) of the electrodeposition paint P1 based on the fluctuations in the measured current value (see FIG. 2). The inventors of the present application have newly confirmed that the fluctuations in the current value and the fluctuations in the acid concentration are synchronized (see FIG. 3). Therefore, if the CPU 52 knows the fluctuations in the current value, it can estimate the acid concentration of the electrodeposition paint P1. Data relating to the acid concentration is stored in the RAM 54 for each vehicle body W1.

[0029] Then, the vehicle body W1 whose acid concentration has been estimated and whose electrodeposition coating has been completed is carried out of the electrodeposition tank 11 and then dried in a drying oven (not shown). Thereafter, the thickness of the electrodeposition paint P1 for each part of the vehicle body W1 is measured (monitored) by the thickness gauge 61 (see FIG. 2). Since the number of vehicles (vehicle bodies W1) produced in the electrodeposition coating facility 10 of this embodiment reaches hundreds of thousands per year, it is difficult to measure the thickness of the film for each part of all the vehicle bodies W1. Therefore, in this embodiment, the first vehicle body W1 (the vehicle body W1 to be painted first) is selected from the multiple vehicle bodies W1 to be painted on the day of measuring the thickness, and the thickness of the film for each part of the selected vehicle body W1 is measured. That is, the measurement of the thickness is performed at the same timing (for example, the Nth vehicle after the start of painting, or N minutes after the start of painting) on ​​all measurement days. The thickness gauge 61 is not particularly limited, but can be appropriately selected from, for example, an electromagnetic thickness gauge, an eddy current thickness gauge, an infrared thickness gauge, an ultrasonic thickness gauge, a spectroscopic interference thickness gauge, and the like. Further, the film thickness meter 61 is connected to the personal computer 50 via a cable (not shown). Therefore, data on the measured film thickness is transmitted to the personal computer 50 via the cable and stored in the RAM 54 for each part of the vehicle body W1.

[0030] The learning unit 55 of the CPU 52 then correlates and learns data on acid concentration (acid concentration data), which are composition condition factors of the electrodeposition paint P1, data on film thickness (film thickness data), and data on current value (current value data), which is an adjustment factor of the electrodeposition coating equipment 10. Specifically, first, the learning unit 55 integrates the film thickness data stored in the RAM 54 with the current value data and acid concentration data also stored in the RAM 54.

[0031] FIG. 4 is a table showing the management data. This table has columns for "ID", "production date and time", and "objective variable". The "ID" column displays the manufacturing number assigned to each vehicle body W1, and the "production date and time" column displays the date and time when the electrocoating for each vehicle body W1 was completed (specifically, the date and time when the vehicle body W1 was carried out of the electrocoating tank 11). The "ID" and "production date and time" columns are associated with data (current value data and acid concentration data) for approximately 10,000 vehicle bodies W1 produced in one week. Furthermore, film thickness data is recorded in part of the "objective variable" column. For example, when film thickness data on March 5, 2020 is obtained, the film thickness data (objective variable A0) is recorded in the "objective variable" column at the beginning of that date (ID is "1"). As a result, the film thickness data is integrated with the current value data and acid concentration data.

[0032] Although the current value data and acid concentration data are present in the same number as the number of produced car bodies W1, the film thickness data is only for about 7 of the approximately 10,000 cars, so the learning unit 55 cannot perform learning with high accuracy using only these film thickness data. Therefore, the learning unit 55 performs a process of interpolating missing values ​​for the input film thickness data. Specifically, every time new film thickness data (for example, the objective variable A1 shown in FIG. 4) is obtained, the learning unit 55 performs a process of drawing a line segment L1 connecting the new film thickness data (objective variable A1) and the film thickness data (objective variable A0) input one day before the objective variable A1 on the graph shown in FIG. 5. As a result, the missing values ​​between the objective variables A0 and A1 (specifically, the film thickness data of the car body W1 with IDs of 2 to 1429) are interpolated. Note that, when there is a clear correlation between the film thickness data and the observation data (current value data and acid concentration data), the missing values ​​are interpolated using a conventionally known regression equation based on a statistical method.

[0033] Thereafter, by comparing the film thickness data with the observed data, the learning unit 55 can obtain new data regarding "what current value and acid concentration are required to achieve the target film thickness." The learning unit 55 then stores the obtained data in the RAM 54 as learned data (past data). That is, the RAM 54 functions as a "storage unit."

[0034] Furthermore, after the learned data is stored in the RAM 54, if any of the current values ​​included in the observation data (current value data) falls outside a certain range (for example, see E1 in FIG. 3), the CPU 52 removes the current value as an abnormal value (outlier). Accordingly, the learned data including the abnormal value is also removed. In this embodiment, when a current is applied to the car body W1 for a longer period than usual due to the stop of the conveyor 21, when the hanger rail 23 is an empty hanger on which the car body W1 is not suspended, or when the integrated amount of the current value applied to the car body W1 is 40% or less of the average due to a malfunction of the electrodeposition coating equipment 10, the current value included in the data is removed as an abnormal value. That is, the CPU 52 also functions as a current abnormal value determination and removal means.

[0035] On the other hand, if there is no abnormal value in the current value, the CPU 52 controls the display 58 to display the estimated results of the film thickness and acid concentration based on the learned model previously set in the ROM 53. In this embodiment, not only the current values ​​(estimated values) of the film thickness and acid concentration but also their trends up to now are displayed. The display of the estimated results is updated in real time every time learned data is stored in the RAM 54.

[0036] Next, the estimation unit 56 of the CPU 52 estimates the film thickness for each part of the vehicle body W1 based on the learned data stored in the RAM 54. Specifically, the estimation unit 56 first estimates an appropriate voltage value to be applied to the vehicle body W1 from the side electrode 32. The appropriate voltage value is determined from the learned data stored in the RAM 54 (specifically, the current value data and film thickness data included in the learned data). The estimation unit 56 also estimates an appropriate acid concentration of the electrodeposition paint P1. The appropriate acid concentration is determined from the learned data stored in the RAM 54 (specifically, the acid concentration data and film thickness data included in the learned data).

[0037] Thereafter, the CPU 52 controls the display 58 to display recommended settings for the side electrode 32 and the electrodeposition paint P1 for achieving a coating thickness within a desired range. Specifically, the display 58 displays predicted coating thicknesses for each part of the vehicle body W1. The display 58 also displays a recommended voltage value to be applied from the side electrode 32 to the vehicle body W1, a recommended acid concentration, a recommended amount of additive 42 to be added, and a recommended amount of filtrate to be disposed of.

[0038] Then, the CPU 52 applies a voltage to the vehicle body W1 from the side electrodes 32 based on the determined appropriate voltage value. As a result, the coating film formed on the surface of the vehicle body W1 is adjusted to approach a targeted thickness range. It is generally known that the coating thickness tends to increase as the voltage value increases. Therefore, it can be said that there is a positive correlation between the voltage value and the coating thickness.

[0039] Furthermore, the CPU 52 adjusts the electrodeposition paint P1 to have the determined appropriate acid concentration. For example, when the acid concentration is low and the amount of acid is reduced, the repulsion between the paint particles contained in the electrodeposition paint P1 weakens, making them more likely to aggregate. As a result, compared to when the acid concentration is high, the coulombic efficiency (amount of deposition per coulomb) is higher, making it easier to deposit the electrodeposition paint P1 on the surface of the vehicle body W1 with a small amount of electricity. Therefore, under the same current application conditions, an excess film thickness is generated. Therefore, it can be said that there is a negative correlation between the acid concentration and the film thickness.

[0040] Therefore, when the acid concentration is low, the CPU 52 adjusts the acid concentration to be higher. Specifically, the CPU 52 operates the additive adding means 41 to adjust the acid concentration. More specifically, the CPU 52 first outputs a drive signal to the additive supply valve. This switches the additive supply valve to an open state, and the additive 42 in the tank passes through the additive supply pipe and is filled into the electrodeposition tank 11 from the additive supply nozzle 43. In other words, the adjustment work to increase the acid concentration is a work of automatically adding (feeding) the additive 42 to the electrodeposition paint P1 in the electrodeposition tank 11.

[0041] On the other hand, if the acid concentration increases, a larger current is required for deposition. As a result, electrolysis increases and a large amount of gas is generated. In addition, a larger current is required for deposition of the electrodeposition paint P1, which reduces the Coulomb efficiency. In this case, deposition takes a long time, making it difficult to ensure a sufficient film thickness.

[0042] Therefore, when the acid concentration is estimated to be high, the CPU 52 adjusts the acid concentration to be lower. Specifically, the CPU 52 operates the liquid component reducing means 44 to reduce the liquid component of the electrodeposition paint P1, thereby lowering the acid concentration. More specifically, the CPU 52 first outputs a drive signal to the electrodeposition paint discharge valve 47. As a result, the electrodeposition paint discharge valve 47 switches to an open state, and the electrodeposition paint P1 is discharged from the electrodeposition paint discharge port 46 to the outside of the electrodeposition tank 11, passes through the circulation pipe 45, and is guided to the filtration device 48. The filtration device 48 then separates the filtrate from the electrodeposition paint P1. Note that the separation of the filtrate reduces the liquid component of the electrodeposition paint P1, and the filtrate separated from the electrodeposition paint P1 is discarded. Thereafter, the electrodeposition paint P1 from which the filtrate has been separated is supplied into the electrodeposition tank 11 from the electrodeposition paint supply port 49. That is, the adjustment work to lower the acid concentration is a work to automatically reduce the liquid component of the electrodeposition paint P1.

[0043] Therefore, according to this embodiment, the following effects can be obtained.

[0044] (1) In this embodiment, the learning unit 55 learns data on the acid concentration, which is a composition condition factor of the electrodeposition paint P1, data on the film thickness, and data on the current value, which is an adjustment factor of the electrodeposition coating equipment 10, by associating them, and the estimation unit 56 estimates the film thickness for each part of the vehicle body W1 based on the data associated by the learning unit 55 (learned data). In this case, since the film thickness can be estimated with almost no time delay after the data is associated, the composition of the electrodeposition paint P1 is prevented from changing significantly before the film thickness is estimated. As a result, even if the composition of the electrodeposition paint P1 changes over time, the coating film formed on the surface of the vehicle body W1 can be set to a targeted thickness range, thereby improving the coating quality of the vehicle body W1. Moreover, if the learning unit 55 has more opportunities to learn, the film thickness for each part of the vehicle body W1 is optimized, and the coating quality becomes more stable. In addition, since there is no need to put an excessive amount of the electrodeposition paint P1 into the electrodeposition tank 11 in anticipation of a change in the composition of the electrodeposition paint P1, loss of the electrodeposition paint P1 can be reduced.

[0045] (2) In this embodiment, when the acid concentration of the electrodeposition paint P1 is high, the CPU 52 adjusts the acid concentration to be low by controlling the electrodeposition paint P1 to reduce the liquid component based on the learned data. As a result, the acid concentration is lowered and the amount of acid is reduced, so the amount of current required for deposition of the electrodeposition paint P1 is reduced and electrolysis is reduced. This reduces the generation of gas, making it possible to prevent the generation of gas pinholes (gas pinholes) in the coating film and improving the coating quality.

[0046] (3) Incidentally, electrodeposition coating is performed on a large number of vehicle bodies W1 (for example, about 10,000 vehicles per week). For this reason, measuring the film thickness of each part of each vehicle body W1 is not realistic because it requires a lot of labor. Therefore, in this embodiment, the film thickness is measured only on the vehicle body W1 that is first painted on the day of measuring the film thickness, and each time a new film thickness is measured, the missing value (film thickness) between the new film thickness (for example, objective variable A1) and the film thickness measured previously (for example, objective variable A0) is automatically interpolated (see Figs. 4 and 5). In other words, film thickness data is automatically given even to vehicle bodies W1 whose film thickness has not been measured, so that even if electrodeposition coating is performed on a large number of vehicle bodies W1, the film thickness of all vehicle bodies W1 can be easily estimated.

[0047] (4) In this embodiment, when the current value measured by the ammeter (not shown) is outside a certain range (see E1 in FIG. 3), the CPU 52 (learning unit 55) removes the current value as an abnormal value that is far from the actual range and obtains the remaining current values ​​(current value data). As a result, the estimation unit 56 can accurately estimate the film thickness for each part of the vehicle body W1 based on the learned data including the current value data.

[0048] The above embodiment may be modified as follows.

[0049] In the above embodiment, the composition condition factor of the electrodeposition paint P1 included in the learned data was the acid concentration (MEQ). However, the composition condition factor may be another one such as NV (non-volatile content), ash content, paint conductivity, and Coulombic efficiency. It is generally known that as the NV increases, the resin components remaining in the coating film when dried increase, and therefore the film thickness tends to increase. Therefore, it can be said that there is a positive correlation between the NV and the film thickness. It is also known that as the ash content increases, the pigment content of the electrodeposition paint P1 increases, the film resistance increases, and the throwing power improves, and therefore the film thickness tends to increase. Therefore, it can be said that there is a positive correlation between the ash content and the film thickness. Furthermore, it is known that as the paint conductivity increases, the coating film becomes easier to form, and therefore the film thickness tends to increase. Therefore, it can be said that there is a positive correlation between the paint conductivity and the film thickness. It is also known that as the Coulombic efficiency increases, the electrodeposition paint P1 can be easily deposited on the surface of the vehicle body W1 with a small amount of electricity, and the film thickness tends to increase. Therefore, it can be said that there is a positive correlation between the Coulombic efficiency and the film thickness. In addition, two or more of the acid concentration, NV, ash content, paint conductivity, and Coulombic efficiency may be selected and used as the composition condition factors.

[0050] However, among the above composition condition factors, NV, ash content, paint conductivity and Coulombic efficiency can only be obtained by taking a sample of the electrodeposition paint P1 from the electrodeposition tank 11 and having an external organization analyze the components of the sample, so it takes time to obtain the results. Incidentally, paint conductivity can be measured using a conductivity meter, but if the conductivity meter is permanently installed in the electrodeposition coating equipment 10, stable measurement values ​​cannot be obtained due to sensor contamination, etc. Therefore, it is preferable that the composition condition factor is the acid concentration.

[0051] In the above embodiment, the adjustment factor of the electrodeposition coating equipment 10 included in the learned data was the current value of the current applied to the vehicle body W1. However, the adjustment factor may be something else, such as the liquid temperature of the electrodeposition paint P1 or the current application time of the side electrode 32. It is generally known that the film thickness tends to increase as the liquid temperature increases. Therefore, it can be said that there is a positive correlation between the liquid temperature and the film thickness. It is also known that the film thickness tends to increase as the current application time increases. Therefore, it can be said that there is a positive correlation between the ash content and the film thickness. It is also possible to select two or more of the current value, the liquid temperature, and the current application time as the adjustment factor.

[0052] In the above embodiment, the current value data is obtained by measuring the current applied to the vehicle body W1 with an ammeter (and is stored in the RAM 54), the acid concentration data is obtained by estimating from the fluctuation of the current value, and the film thickness data is obtained by measuring the film thickness of the electrodeposition paint P1 with the film thickness meter 61. However, these data may be recorded and managed on a slip (paper) and manually entered by an operator using the keyboard 57 to be stored in the RAM 54.

[0053] In the above embodiment, the current value data, acid concentration data, and film thickness data are obtained every day, but these data may be obtained every few days. Also, the film thickness data is obtained by measuring the film thickness of the vehicle body W1 that is painted first on the film thickness measurement date, but it may be obtained by measuring the film thickness of the vehicle body W1 that is painted second or later on the measurement date. Furthermore, only one film thickness data is obtained per day, but two or more film thickness data may be obtained per day.

[0054] In the above embodiment, the liquid component of the electrodeposition paint P1 is reduced by separating the filtrate from the electrodeposition paint P1 using the filtration device 48, but the liquid component may be reduced by other methods. For example, the liquid component of the electrodeposition paint P1 may be reduced by evaporating it, or the liquid component may be reduced by separating the filtrate from the electrodeposition paint P1 using a centrifuge. Also, in the above embodiment, the acid concentration is adjusted to be low by reducing the liquid component of the electrodeposition paint P1, but the acid concentration may be adjusted to be low by adding an alkali component to the electrodeposition paint P1.

[0055] Next, in addition to the technical ideas described in the claims, the technical ideas grasped by the above-mentioned embodiments will be listed below.

[0056] (1) A film thickness estimation system for an electrocoating facility, as claimed in any one of claims 1 to 3, characterized in that the data on the film thickness is obtained by selecting a specific vehicle body from a plurality of vehicle bodies that are painted on the day the film thickness is measured, and measuring the film thickness of the selected vehicle body.

[0057] (2) In any one of claims 1 to 3, the learning unit performs a process of interpolating missing values ​​between the currently obtained data on the film thickness and the previously obtained data on the film thickness, each time new data on the film thickness is obtained.

[0058] (3) In claim 3, the adjustment factor of the electrodeposition coating equipment is a current value of a current applied to the vehicle body, and the system further comprises a current abnormality determination and removal means for removing a current value outside a certain range as an abnormal value when the current value included in the data relating to the adjustment factor of the electrodeposition coating equipment is outside a certain range.

[0059] (4) In any one of claims 1 to 3, the transport means includes a rail and a plurality of hanger rails that are attached to the rails and transport the vehicle body by suspending it thereon, each of the hanger rails is provided with a pulse generator that periodically transmits a pulse signal, and the film thickness estimation system for an electrocoating facility is characterized in that ...

[0060] (5) In any one of claims 1 to 3, the composition condition factor of the electrodeposition paint is an acid concentration, and the system includes an additive adding means for adding an additive to the electrodeposition paint and a liquid component reducing means for reducing the liquid component of the electrodeposition paint, and the adjustment work for increasing the acid concentration is the work of adding the additive to the electrodeposition paint, and the adjustment work for decreasing the acid concentration is the work of reducing the liquid component of the electrodeposition paint. In this case, the additive adding means and the liquid component reducing means are operated to automatically perform the work of adding additives to the electrodeposition paint and the work of reducing the liquid component of the electrodeposition paint. Therefore, the operator does not have to perform the work of adding additives or the work of reducing liquid components, and the operator's workload is reduced. [Explanation of symbols]

[0061] 1. Film thickness estimation system 10...Electrochemical painting equipment 11...electrodeposition bath 21...Conveyor as a means of transportation 31...Electrode 54…RAM as memory 55…Learning Department 56…Estimation part P1…electrodeposition paint W1: Body

Claims

1. A system for estimating a film thickness of an electrodeposition paint for each part of a vehicle body in an electrodeposition coating facility including an electrodeposition tank for storing electrodeposition paint and transporting a vehicle body while the vehicle body is immersed in the electrodeposition paint, a plurality of electrodes arranged in the electrodeposition tank, and a transport means for transporting the vehicle body, the system comprising: A learning unit that learns data on composition condition factors of the electrodeposition paint, data on the film thickness, and data on adjustment factors of the electrodeposition coating equipment by associating them with each other; a storage unit that stores the data associated by the learning unit as learned data; an estimation unit that estimates the film thickness for each part of the vehicle body based on the learned data; Equipped with The adjustment factors of the electrodeposition coating equipment include a current value of a current applied to the vehicle body, The learning unit is a missing value interpolation process for interpolating missing values ​​between the currently obtained data on the film thickness and the previously obtained data on the film thickness each time the data on the film thickness is newly obtained; a current abnormal value removal process for determining, when the current value included in the data related to the adjustment factors of the electrodeposition coating equipment is outside a certain range, that the current value outside the certain range is an abnormal value and removing it from the learning data; Do the following: The estimation unit estimates the film thickness for each part of the vehicle body based on the learned data after the missing value interpolation process and the current abnormal value removal process are performed. A film thickness estimation system for an electrodeposition coating equipment.

2. 2. The film thickness estimation system in an electrodeposition coating equipment according to claim 1, wherein the composition condition factor of the electrodeposition coating is at least one selected from the group consisting of acid concentration (MEQ), NV (non-volatile content), ash content, coating conductivity, and Coulomb efficiency.

3. The film thickness estimation system in an electrodeposition coating equipment as described in claim 1 or 2, characterized in that the adjustment factor of the electrodeposition coating equipment is at least one selected from the current value of the current applied to the vehicle body, the liquid temperature of the electrodeposition paint, and the current flow time of the electrode.

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