JP7459213B1 - Electrodeposition equipment - Google Patents

Abstract

[Problem] To reduce the cost of a filtration device. [Solution] An electrodeposition apparatus including an electrodeposition tank for electrodeposition coating an object, a multi-stage water washing tank provided downstream of the electrodeposition tank in the transport direction of the object for washing the object with water, and a filtration device capable of filtering liquid and supplying a concentrated liquid concentrated by the filtering operation to the electrodeposition tank, the filtration device obtaining liquid from at least one of the multi-stage water washing tanks and performing the filtering operation without obtaining liquid from the electrodeposition tank. [Selected Figure] Figure 1

Description

The present invention relates to an electrodeposition apparatus.

Conventionally, electrodeposition coating has been widely used for coating automobile bodies, automobile parts, building materials, and the like. In general, the electrodeposition coating process includes an electrodeposition process to electrochemically form a coating film on the object, a water washing process to wash away unelectrodeposited paint, etc., and a drying process to harden the coating film.

Patent Document 1 discloses a configuration in which a UF (Ultra Filtration) device (filtration device) connected to an electrodeposition tank and a UF device connected to a washing tank are arranged in order to reduce loss of electrodeposition paint. Disclosed.

Japanese Patent Application Laid-Open No. 7-224397

However, in the technology described in Patent Document 1, since the electrodeposition paint is recovered by returning the low concentration liquid in the washing tank to the electrodeposition tank, the amount of liquid returned to the electrodeposition tank increases and It is necessary to extract the filtrate from the electrodeposition solution and supply it to the washing side. Therefore, even when a filtration device is provided on the washing tank side, a filtration device is required on the electrodeposition tank side, and there is a problem that the cost of introducing the filtration device becomes high.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a technique for reducing the cost of a filtration device.

In order to achieve the above object, an electrodeposition apparatus according to one aspect of the present invention includes:
an electrodeposition bath for electrocoating the object;
a first washing tank that is provided downstream of the electrodeposition tank in the transport direction of the object and that washes the object ; and a first washing tank that is provided downstream of the first washing tank that washes the object. A multi-stage rinsing tank including a final rinsing tank ;
A filtration operation is performed to filter the liquid supplied from at least one of the plurality of washing tanks without obtaining the liquid from the electrodeposition tank , and the concentrated liquid concentrated by the filtration operation is transferred to the electrodeposition tank. filtration equipment that can be supplied;
a first detection means for detecting the height of the liquid level in the electrodeposition tank;
a control means for suppressing supply of concentrated liquid from the filtration device to the electrodeposition tank when the height of the liquid level in the electrodeposition tank is equal to or higher than a first threshold;
In an electrodeposition apparatus comprising:
The concentrated liquid increased by suppressing the supply of the concentrated liquid to the electrodeposition tank by the control means is supplied to the first washing tank .

According to the present invention, it is possible to reduce the cost of a filtration device.

1 is a diagram showing an example of the overall configuration of an electrodeposition apparatus according to Embodiment 1. FIG. FIG. 2 is a diagram illustrating an example of a hardware configuration of a control unit included in an electrodeposition apparatus according to an embodiment. FIG. 3 is an explanatory diagram of components connected to a control unit included in the electrodeposition apparatus according to one embodiment. 7 is a flowchart showing a procedure of processing performed by a control unit of an electrodeposition apparatus according to a second embodiment. 7 is a flowchart illustrating a procedure of processing performed by a control unit of an electrodeposition apparatus according to Embodiment 3. FIG. 7 is a diagram showing an example of the overall configuration of an electrodeposition apparatus according to Embodiment 4. FIG. 3 is a diagram showing the configuration of an electrodeposition apparatus according to a comparative example.

Hereinafter, embodiments will be described in detail with reference to the accompanying drawings. Note that the following embodiments do not limit the claimed invention, and not all combinations of features described in the embodiments are essential to the invention. Two or more features among the plurality of features described in the embodiments may be arbitrarily combined. In addition, the same or similar configurations are given the same reference numerals, and duplicate explanations will be omitted.

(Embodiment 1)
First, with reference to FIG. 1, an example of the overall configuration of an electrodeposition apparatus according to this embodiment will be described. In the present embodiment, an automobile body will be described as an example of an object to be subjected to electrodeposition coating. In a production line, an automobile body is first electrocoated in an electrodeposition bath, then transported to a washing layer, and washed with water in the washing layer.

In FIG. 1, 10 is an electrodeposition device. 15 indicates the conveyance direction of the vehicle body. The vehicle body is transported from upstream to downstream along the transport direction 15, and an electrodeposition coating process and a water washing process are sequentially performed. Reference numeral 101 denotes an electrodeposition bath for electrocoating the vehicle body. 102 is a spray device for washing the car body with water using the washing liquid in the first washing tank 103 after the car body is electrocoated in the electrodeposition tank 101 and before being washed in the first washing tank 103. . A return path may be provided for returning the washing liquid sprayed onto the vehicle body by the spray device 102 and falling to the first washing tank 103. For example, the return path may be configured to have an inclination so that the washing liquid sprayed onto the vehicle body and dropped returns to the first washing tank 103 by its own weight. That is, an inclined surface or an inclined flow path may be formed so that the electrodeposition tank 101 side is higher and the washing tank 103 side is lower. However, the spray device 102 provides an additional cleaning function and is not an essential component.

103 is a first water washing tank for washing the vehicle body, which is provided downstream of the electrodeposition tank 101 in the vehicle body transport direction. 103a is a spray device for further washing the vehicle body that has been transported to the first water washing tank 103 after being washed with water by the spray device 102. 104 is a second water washing tank for washing the vehicle body, which is provided downstream of the first water washing tank 103 in the vehicle body transport direction.

A third washing tank 105 is provided downstream of the second washing tank 104 in the transport direction of the vehicle body, and is used to wash the vehicle body. 105a is a spray device for further washing the vehicle body that has been washed in the second washing tank 104 and then transported to the third washing tank 105 side. 106 is a pure water washing tank provided downstream of the third washing tank 105 in the transport direction of the vehicle body, and for washing the vehicle body using pure water.

A filtration device 107 is capable of filtering a liquid and supplying a concentrated liquid to an electrodeposition tank according to the filtration of the liquid. In the illustrated example, the filtration device 107 is connected to the first rinsing tank 103, and is configured to obtain liquid (rinsing liquid) from the first rinsing tank 103 and filter it. Alternatively, it may be connected to the second rinsing tank 104 or the third rinsing tank 105 to acquire liquid (rinsing liquid) from the second rinsing tank 104 or the third rinsing tank 105 and filter it. Alternatively, it may be connected to two or more of the first rinsing tank 103, the second rinsing tank 104, and the third rinsing tank 105 to acquire and filter the liquid (rinsing liquid) from each rinsing tank. Good too.

108 is a storage tank that temporarily stores the filtrate that has been filtered by the filtration device 107 and whose concentration has been reduced. The filtration device 107 is connected to the third washing tank 105 via a storage tank 108, and supplies the filtered filtrate whose concentration has been reduced to the third washing tank 105.

Reference numeral 109 denotes a flow path that connects the third rinsing tank 105 and the second rinsing tank 104 and supplies the liquid (rinsing liquid) from the third rinsing tank 105 to the second rinsing tank 104 . A channel 110 connects the second washing tank 104 and the first washing tank 103 and supplies the liquid (washing liquid) from the second washing tank 104 to the first washing tank 103. Note that a flow path may be further provided that connects the first washing tank 103 and the electrodeposition tank 101 and supplies the liquid (rinsing liquid) from the first washing tank 103 to the electrodeposition tank 101.

Each rinsing tank may be configured such that, for example, the liquid level height of the third rinsing tank 105 > the liquid level height of the second rinsing tank 104 > the liquid level height of the first rinsing tank 103. . As a result, liquid (rinsing liquid) flows from the third rinsing tank 105 to the second rinsing tank 104 and from the second rinsing tank 104 to the first rinsing tank 103.

Reference numeral 111 denotes an electrodeposition tank side valve provided on a flow path connecting the filtration device 107 and the electrodeposition tank 101. By opening and closing the electrodeposition tank side valve 111, supply of the concentrated liquid produced as a result of the filtering operation by the filter device 107 to the electrodeposition tank 101 can be suppressed or blocked. In the opening/closing operation, it is possible to continuously transition between the open state and the closed state, and it is possible to control (adjust) the flow rate according to the degree of opening. The opening/closing operation of the electrodeposition tank side valve 111 is controlled by a control section 300, which will be described later.

Reference numeral 112 denotes a washing tank side valve provided on a flow path connecting the filtration device 107 and the first washing tank 103. By opening and closing the washing tank side valve 112, it is possible to suppress or block the filtrate produced as a result of the filtration operation by the filtration device 107 from being supplied to the first washing tank 103. In the opening/closing operation, it is possible to continuously transition between an open state and a closed state, and it is possible to control (adjust) the flow rate according to the degree of opening. The opening/closing operation of the washing tank side valve 112 is controlled by a control unit 300 which will be described later.

151 is an electrodeposition tank liquid level sensor that detects the liquid level in the electrodeposition tank 101. 152 is a water washing tank liquid level sensor that detects the liquid level in the first water washing tank 103.

201 shows the supply of electrodeposition paint to the electrodeposition tank 101. The electrodeposition liquid (electrodeposition paint liquid) containing the electrodeposition paint adheres to the car body through the electrodeposition operation on the car body, so that the amount of the electrodeposition paint in the electrodeposition tank 101 decreases. Furthermore, when the vehicle body is lifted from the electrodeposition tank 101 and transported to the first washing tank 103, the amount of electrodeposition paint that falls off the vehicle body is also reduced. In this way, the electrodeposition bath 101 is carried out to the outside. The electrodeposition paint taken out is replenished into the electrodeposition tank 101 as needed.

202 indicates supply of pure water to the electrodeposition tank 101. In this embodiment, pure water is supplied at 4.3 L/min. 203 indicates supply of pure water to the third washing tank 105. In this embodiment, pure water is supplied at 4.3 L/min.

Here, the NV (Non Volatile) value is a value indicating the nonvolatile content of the paint, and can be determined by (mass of paint after drying)/(mass of paint before drying) x 100. In this embodiment, NV=20% in the electrodeposition tank 101, NV=4.6% in the first washing tank 103, NV=1.3% in the second washing tank 104, and NV=1.3% in the third washing tank 105. NV=0.6%, and in the storage tank 108, NV=0.5%. In the flow path from the first washing tank 103 to the filtration device 107, the washing liquid flows at a rate of 47.3 L/min. The concentrated liquid produced as a result of being filtered by the filtration device 107 has an NV of 46% and is supplied to at least one of the electrolytic cell 101 and the first washing tank 103 at a flow rate of 4.3 L/min. On the other hand, in the flow path from the storage tank 108 to the third washing tank 105, the filtrate flows to the third washing tank 105 at a flow rate of 43 L/min.

Therefore, the concentration rate by the filtration device 107 is 46% (NV after concentration supplied from the filtration device 107 to at least one of the electrodeposition tank 101 and the first water washing tank 103) ÷ 4.6% (NV before concentration in the first water washing tank 103) = 10 times.

On the other hand, with reference to the comparative example shown in FIG. 7, a case will be described in which the liquid in the electrodeposition tank 101 with NV=20% is directly filtered. In FIG. 7, the same components as in this embodiment are given the same reference numerals, and their explanation will be omitted. In the comparative example shown in FIG. 7, the electrodeposition tank 101 and the filtration device 701 are connected, and the liquid (NV=20%) in the electrodeposition tank 101 is supplied to the filtration device 701 at a rate of 1000 L/min. The concentrated liquid (NV=20.8%) filtered and concentrated by the filtration device 701 is returned to the electrodeposition tank 101 at a rate of 950 L/min. On the other hand, the filtrate, which has been filtered by the filtration device 701 and has a lower concentration, is supplied to the third washing tank 105 via the storage tank 108 at a rate of 50 L/min. In the case of such a configuration, the electrodeposition coating liquid adhered to the vehicle body and taken out from the electrodeposition tank 101 is recovered via the flow path 702.

In the case of the comparative example shown in FIG. 7, the concentration ratio by the filtration device 107 is 20.8% (NV after concentration supplied from the filtration device 701 to the electrodeposition tank 101)/20% (from the electrodeposition tank 101 to the filtration device 107). NV before concentration supplied to ) = 1.04 times.

In this way, when the liquid in the electrodeposition tank 101 with NV=20% is directly filtered, the concentration ratio is usually about 1.02 to 1.04 times (1.04 times in the comparative example shown in FIG. 7). . On the other hand, when filtering the liquid in the first washing tank 103 whose NV is 2% to 5% (4.6% in this embodiment), the concentration ratio is usually about 10 times (10 times in this embodiment). ). In this way, when the NV of the liquid to be filtered is low, the concentration ratio can be increased. This is because it is more efficient to filter a liquid with a low concentration than to filter a liquid with a high concentration.

Note that the filtration device 107 can be configured to include one or more UF membranes. This UF membrane has a characteristic that the sampling rate of the filtrate changes depending on the NV value of the liquid to be filtered. For example, when a certain UF membrane directly filters the liquid in the electrodeposition tank 101 with NV=20%, the filtrate whose concentration has been reduced by filtration is 5 L/min/piece, that is, per UF membrane. It has the characteristic that it can be collected at a rate of 5L/min. On the other hand, when filtering the liquid in the first washing tank 103 whose NV is 2% to 5% (4.6% in this embodiment), the filtrate whose concentration has decreased due to filtration is 20 to 25 L/min. It has the characteristic that it can be collected at a rate of 20 to 25 L/min per UF membrane.

In this embodiment, if three UF membranes are arranged, the flow rate will be 60 to 75 L/min, which exceeds the flow rate (43 L/min) flowing from the filtration device 107 to the third washing tank 105 via the storage tank 108. Therefore, in this embodiment, it is sufficient to arrange three UF membranes.

On the other hand, in the case of the comparative example shown in FIG. 7 in which the liquid in the electrodeposition tank 101 with NV=20% is directly filtered, the flow rate of the filtrate whose concentration has been reduced by filtration is 5 L/min/bottle. Considering this, in order for the flow rate flowing from the filtration device 701 into the third washing tank 105 via the storage tank 108 to be 50 L/min or more, it is necessary to arrange ten UF membranes.

As described above, according to the configuration of this embodiment, compared to the comparative example shown in FIG. 7, it is possible to achieve a higher concentration ratio, reduce the number of required UF membranes, and reduce the cost of introducing a filtration device. can do.

As described above, in this embodiment, the liquid (having a relatively low NV value) obtained from the first washing tank 103 is filtered by the filtering device 107, and the concentrated liquid is returned to the electrodeposition tank. Then, the filtration device 107 does not acquire the liquid (electrodeposition paint liquid) from the electrodeposition tank 101. That is, there is no provision for obtaining and filtering the liquid (electrodeposition paint liquid) from the electrodeposition tank 101.

Thereby, the required number of UF membranes can be reduced while reducing the loss of electrodeposition paint. Alternatively, if the number of UF membranes is not changed, the frequency of replacing the UF membranes can be reduced. Further, a filtration device for filtering the liquid obtained from the electrodeposition tank 101 is not required. Therefore, it is possible to reduce the cost of the UF device (UF membrane) while reducing the loss of electrodeposition paint.

(Embodiment 2)
In this embodiment, an example of controlling the liquid level using the electrodeposition apparatus 10 shown in Embodiment 1 will be described.

<Hardware configuration>
FIG. 2 is a diagram illustrating an example of the hardware configuration of a control unit included in an electrodeposition apparatus according to an embodiment. The control unit 300 includes a CPU 3001, a ROM 3002, a RAM 3003, an I/F 3004, an input device 3005, and an output device 3006.

The CPU 3001 executes processing by reading and executing computer programs stored in the ROM 3002 and RAM 3003. Note that at least part of the processing by the CPU 211 may be executed by dedicated hardware. Examples of specialized hardware include ASICs (Application Specific Integrated Circuits), FPGAs (Field Programmable Gate Arrays), DSPs (Digital Signal Processors), and PLCs (Programmable Logic Controllers).

ROM 3002 stores computer programs that do not require modification. RAM 3003 temporarily stores various data. I/F 3004 is, for example, a communication interface used for communication with various sensors (electrodeposition tank liquid level sensor 151, water rinsing tank liquid level sensor 152, etc.) and/or various valves (electrodeposition tank side valve 111, water rinsing tank side valve 112, etc.). Input device 3005 can accept various inputs, and is, for example, an input device such as a keyboard or mouse, or a touch panel. Output device 3006 can perform various outputs, and can be, for example, a display unit, a speaker, etc.

Note that not all of the components shown in FIG. 2 are essential. For example, the input device 3005 and the output device 3006 may not be provided.

<Relationship between the control unit, sensors, and valves>
Next, FIG. 3 is an explanatory diagram of components connected to a control unit included in an electrodeposition apparatus according to an embodiment. The control unit 300 is connected to the electrodeposition tank liquid level sensor 151, the washing tank liquid level sensor 152, the electrodeposition tank side valve 151, and the washing tank side valve 112.

The control unit 300 acquires the detection result of the electrodeposition tank liquid level sensor 151 and/or the detection result of the washing tank liquid level sensor 152. Then, based on the detection results, the opening/closing operations of the electrodeposition tank side valve 111 and/or the washing tank side valve 112 are controlled. That is, the control unit 300 controls the flow from the filtration device 107 to the electrodeposition tank 101 and/or the first washing tank 103 based on the liquid level height of the electrodeposition tank 101 and/or the liquid level height of the first washing tank 103. The flow rate of the concentrated liquid supplied to 103 is controlled. The control unit 300 can suppress or cut off the flow rate of the concentrated liquid by continuously controlling the opening degree of the electrodeposition tank side valve 111 and/or the washing tank side valve 112.

<Processing>
Next, with reference to the flowchart of FIG. 4, the procedure of processing performed by the control unit according to the present embodiment will be described.

In S401, the control unit 300 acquires the detection result of the electrodeposition tank liquid level sensor 151. In S<b>402 , the control unit 300 determines whether the liquid level height of the electrodeposition tank 101 is equal to or higher than the first threshold value based on the detection result of the electrodeposition tank liquid level sensor 151 . If this step is YES, the process advances to S403. On the other hand, if this step is NO, the process advances to S406.

In S403, the control unit 300 suppresses the supply of the concentrated liquid to the electrodeposition tank by controlling the opening degree of the electrodeposition tank side valve 111 to be lowered. In S404, the control unit 300 determines whether the liquid level height of the electrodeposition tank 101 is equal to or higher than a second threshold value that is larger than the first threshold value. If this step is YES, the process advances to S405. On the other hand, if this step is NO, the process advances to S406.

In S405, the control unit 300 controls the opening degree of the electrodeposition tank side valve 111 to zero, thereby cutting off the supply of the concentrated liquid to the electrodeposition tank.

In S406, the control unit 300 determines whether to continue the series of processes. If this step is YES, the process returns to S401. On the other hand, if this step is NO, the process ends. In addition, even when the car body electrodeposition painting line is in operation, and even when it is not in operation, it is necessary to constantly stir the paint in the electrodeposition tank and washing tank to prevent it from settling. Height adjustment will be performed all the time, and a series of processes will be repeated. On the other hand, if a situation occurs where it is necessary to temporarily stop the processing, such as equipment failure, the processing may be terminated. Furthermore, in the event that some kind of error occurs, the control unit 300 may issue an alert via the output device 3006.

As explained above, in this embodiment, the liquid level height of the electrodeposition tank is monitored, and when the liquid level height of the electrodeposition tank increases, the supply of concentrated liquid to the electrodeposition tank is suppressed or control to shut off and lower the liquid level. This makes it possible to maintain the liquid level in the electrodeposition tank at an appropriate height.

In this embodiment, when the liquid level of the electrodeposition tank increases, the opening degree of the electrodeposition tank side valve 111 is adjusted in order to suppress or cut off the supply of concentrated liquid to the electrodeposition tank. Although an example has been described, the configuration may be such that the opening degree of the flush tank side valve 112 is increased. Alternatively, both the electrodeposition tank side valve 111 and the washing tank side valve 112 may be controlled.

(Embodiment 3)
In the second embodiment, an example was described in which the supply of the concentrated liquid to the electrodeposition tank is controlled based on the liquid level in the electrodeposition tank. In contrast, in the present embodiment, an example is described in which the supply of the concentrated liquid to the electrodeposition tank is controlled based on the liquid level in the first water washing tank.

Note that the configuration of the control unit 300 is the same as that described in Embodiment 2 with reference to FIGS. 2 and 3, so a description thereof will be omitted.

<Processing>
With reference to the flowchart of FIG. 5, the procedure of processing performed by the control unit according to this embodiment will be described.

In S501, the control unit 300 acquires the detection result of the washing tank liquid level sensor 152. In S<b>502 , the control unit 300 determines whether the liquid level height of the first washing tank 103 is equal to or lower than the third threshold based on the detection result of the washing tank liquid level sensor 152 . If this step is YES, the process advances to S503. On the other hand, if this step is NO, the process advances to S504.

In S503, the control unit 300 controls the electrodeposition tank side valve 111 to suppress or cut off the supply of the concentrated liquid to the electrodeposition tank. More specifically, control is performed to reduce the opening degree of the electrodeposition tank side valve 111 or to make it zero.

In S504, the control unit 300 determines whether to continue the series of processing. If this step is YES, the process returns to S501. On the other hand, if this step is NO, the process ends. In addition, even when the car body electrodeposition painting line is in operation, and even when it is not in operation, it is necessary to constantly stir the paint in the electrodeposition tank and washing tank to prevent it from settling. Height adjustment will be performed all the time, and a series of processes will be repeated. On the other hand, if a situation occurs where it is necessary to temporarily stop the processing, such as equipment failure, the processing may be terminated. Furthermore, in the event that some kind of error occurs, the control unit 300 may issue an alert via the output device 3006.

As explained above, in this embodiment, the liquid level height of the first washing tank is monitored, and when the liquid level height of the first washing tank decreases, the concentrated liquid is transferred to the electrodeposition tank. The supply is suppressed or cut off, and the amount of liquid is controlled to flow into the first washing tank. This makes it possible to maintain the liquid level in the first washing tank at an appropriate height.

Note that in this embodiment, an example has been described in which the supply of the concentrated liquid to the electrodeposition tank is suppressed or cut off depending on the comparison with one threshold value (third threshold value), but similarly to the flowchart of FIG. 4, Two threshold values may be provided. In that case, as in the process shown in FIG. 4, supply of the concentrated liquid to the electrodeposition tank may be suppressed, for example, when the liquid level height of the first washing tank is equal to or lower than the third threshold value. Then, the supply of the concentrated liquid to the electrodeposition tank may be cut off when the liquid level height of the first washing tank is equal to or lower than a fourth threshold value, which is smaller than the third threshold value.

Furthermore, in this embodiment, when the liquid level in the first washing tank decreases, the opening degree of the electrodeposition tank side valve 111 is adjusted to suppress or cut off the supply of concentrated liquid to the electrodeposition tank. Although an example of adjustment has been described, the opening degree of the washing tank side valve 112 may be increased. Alternatively, both the electrodeposition tank side valve 111 and the washing tank side valve 112 may be controlled.

(Embodiment 4)
This embodiment is an example in which the number of washing tanks is reduced compared to that of embodiment 1. By reducing the number of washing tanks, the number of washing steps can be reduced, and the process length can be shortened.

An example of the overall configuration of the electrodeposition apparatus according to this embodiment will be described with reference to FIG. 6. In FIG. 6, the same reference numerals as those in Embodiment 1 indicate the same components, so duplicate explanation will be omitted. The electrodeposition apparatus 20 of the fourth embodiment differs from the electrodeposition apparatus 10 of the first embodiment in that the third washing tank 105 is removed. That is, in Embodiment 4, the car body is electrodeposited in an electrodeposition tank 101, washed with water in a first washing tank 103, further washed with water in a second washing tank 104, and then washed with pure water. It is transported to tank 106.

In the fourth embodiment, the pure water supplied to the electrodeposition tank 101 has a flow rate of 10 L/min, and the pure water supplied to the third washing tank 105 also has a flow rate of 10 L/min. Further, in the fourth embodiment, NV=20% in the electrodeposition tank 101, NV=2.2% in the first washing tank 103, NV=0.6% in the second washing tank 104, and NV in the storage tank 108. =0.5%. In the flow path from the first washing tank 103 to the filtration device 107, the washing liquid flows at a rate of 110 L/min. The concentrated liquid produced as a result of being filtered by the filtration device 107 has NV=22%, and is supplied to at least one of the electrolytic cell 101 and the first washing tank 103 at a flow rate of 10 L/min. On the other hand, in the flow path from the storage tank 108 to the third washing tank 105, the filtrate flows to the third washing tank 105 at a flow rate of 100 L/min.

Therefore, the concentration ratio by the filtration device 107 is 22% (NV after concentration supplied from the filtration device 107 to at least one of the electrodeposition tank 101 and the first washing tank 103)/2.2% (first washing tank 103). NV before concentration in tank 103) = 10 times.

As described in Embodiment 1, when directly filtering the liquid in the electrodeposition tank 101 with NV=20%, the concentration ratio is usually about 1.02 to 1.04 times. On the other hand, when filtering the liquid in the first washing tank 103 with NV=2% to 5% (4.6% in the first embodiment), the concentration ratio is about 10 times in the fourth embodiment. In this way, when the NV of the liquid to be filtered is low, the concentration ratio can be increased. This is because it is more efficient to filter a liquid with a low concentration than to filter a liquid with a high concentration.

As described in the first embodiment, the filtration device 107 can be configured to include one or more UF membranes. As described above, this UF membrane has the characteristic that the collection speed of the filtrate changes depending on the NV value of the liquid to be filtered.

As described in Embodiment 1, when a certain UF membrane directly filters the liquid in the electrodeposition tank 101 with NV=20%, the filtrate whose concentration has been reduced by filtration is 5 L/min/bottom, i.e. , it has the characteristic that it can be collected at a rate of 5 L/min per UF membrane. On the other hand, when filtering the liquid in the first washing tank 103 whose NV is 2% to 5% (2.2% in the fourth embodiment), the filtrate whose concentration has been reduced by filtration is 20 to 25 L/min. It has the characteristic that it can be collected at a rate of 20 to 25 L/min per UF membrane.

In the fourth embodiment, if five UF membranes are arranged, the flow rate becomes 100 to 125 L/min, which exceeds the 100 L/min flowing from the filtration device 107 to the third washing tank 105 via the storage tank 108. Therefore, in the fourth embodiment, five UF membranes may be arranged. On the other hand, in the comparative example of FIG. 7 in which the liquid in the electrodeposition tank 101 with NV=20% is directly filtered, it is necessary to arrange ten UF membranes.

In this manner, as in this embodiment, by filtering the liquid (with a relatively low NV value) obtained from the first water washing tank 103 using the filtration device 107 and returning the concentrated liquid to the electrodeposition tank, the number of UF membranes required can be reduced while reducing the loss of electrodeposition paint. Alternatively, if the number is not changed, the frequency of replacing the UF membranes can be reduced. In addition, a filtration device for filtering the liquid obtained from the electrodeposition tank 101 is not required. Therefore, it is possible to reduce the cost of the UF device (UF membrane) while reducing the loss of electrodeposition paint.

Furthermore, according to this embodiment, the number of washing tanks can be reduced, so the process length can be reduced (from three washing steps to two washing steps). Therefore, it is also possible to reduce the cost of the washing tank.

[Modified example]
In each of the embodiments described above, the body of an automobile was used as an example of the object to be electrodeposited, but the object is not limited to the body of an automobile. For example, the object may be an automobile part, a building material, or any other industrial product.

Further, in each of the above-described embodiments, only one filtration device 107 is disposed, and the filtration device 107 is not connected to the electrodeposition tank 101, liquid is not supplied from the electrodeposition tank 101, and there are multiple stages. An example has been described in which a liquid (washing liquid) is supplied from at least one of the washing layers. However, it is not limited to this example. The electrodeposition device may include multiple filtration devices. In that case, all of the plurality of filtration devices do not acquire the liquid from the electrodeposition tank 101 and filter it, but acquire the liquid from at least one of the multiple stages of washing layers other than the electrodeposition tank 101 and filter it. You can configure it like this.

For example, a second filtration device separate from the filtration device 107 is further provided, and the second filtration device is connected to, for example, the second washing tank 104, and acquires the washing liquid from the second washing tank 104 and filters it. You may. The second filtration device may supply the concentrated liquid produced as a result of the filtration operation to the electrodeposition tank 101, and supply the filtrate whose concentration has decreased as a result of the filtration operation to the third washing tank 105. .

Alternatively, for example, a third filtration device separate from the filtration device 107 and the second filtration device is provided, and the third filtration device is connected to, for example, the third washing tank 105. The washing liquid may be obtained and filtered. The third filtration device may supply the concentrated liquid produced as a result of the filtration operation to the electrodeposition tank 101, and return the filtrate whose concentration has decreased as a result of the filtration operation to the third washing tank 105. . Further, the second filtration device and the third filtration device may supply the concentrated liquid to a washing tank one or more stages upstream, instead of directly supplying the concentrated liquid to the electrodeposition tank.

In this way, a plurality of filtration devices may be included that perform a filtration operation by acquiring liquid from at least one of the multiple stages of washing tanks. Even when multiple filtration devices are provided, by not providing a configuration for obtaining and filtering the liquid from the electrodeposition tank 101, it is possible to achieve a high concentration ratio and extend the life of the UF membrane of the filtration device. Therefore, it is possible to reduce the cost of introducing a filtration device.

By configuring the filtration device 107 (and the filtration device if a further filtration device is provided) so that it is not directly (or indirectly) connected to the electrodeposition tank 101, or by configuring the device so that it does not include any filtration device that obtains liquid from the electrodeposition tank 101 and performs the filtering operation, it is possible to achieve a high concentration ratio while extending the life of the UF membrane of the filtration device, thereby reducing the introduction cost of the filtration device.

The invention is not limited to the above-described embodiments, and various modifications and changes can be made within the scope of the invention.

10, 20: electrodeposition device, 101: electrodeposition tank, 103: first washing tank, 104: second washing tank, 105: third washing tank, 106: pure water washing tank, 107: filtration device, 108: storage tank, 111: electrodeposition tank side valve, 112: washing tank side valve, 151: electrodeposition tank liquid level sensor, 152: washing tank liquid level sensor 152, control section: 300

Claims (11)

an electrodeposition bath for electrocoating the object;
a first washing tank that is provided downstream of the electrodeposition tank in the transport direction of the object and that washes the object ; and a first washing tank that is provided downstream of the first washing tank that washes the object. A multi-stage rinsing tank including a final rinsing tank ;
A filtration operation is performed to filter the liquid supplied from at least one of the plurality of washing tanks without obtaining the liquid from the electrodeposition tank , and the concentrated liquid concentrated by the filtration operation is transferred to the electrodeposition tank. filtration equipment that can be supplied;
a first detection means for detecting the height of the liquid level in the electrodeposition tank;
a control means for suppressing supply of concentrated liquid from the filtration device to the electrodeposition tank when the height of the liquid level in the electrodeposition tank is equal to or higher than a first threshold;
In an electrodeposition apparatus comprising:
An electrodeposition apparatus, wherein the concentrated liquid increased by suppressing the supply of the concentrated liquid to the electrodeposition tank by the control means is supplied to the first washing tank . 2. The electrodeposition apparatus according to claim 1, wherein the filtering device filters the liquid supplied from the first water washing tank. 3. The electrodeposition apparatus according to claim 2, wherein the filtration device supplies the filtrate whose concentration has been reduced by the filtration operation to the final stage washing tank. 3. The electrodeposition apparatus according to claim 2, further comprising a pure water washing tank provided downstream of the final stage washing tank for washing the object with pure water . The control means controls supply of concentrated liquid from the filtration device to the electrodeposition tank when the height of the liquid level in the electrodeposition tank is equal to or higher than a second threshold value that is larger than the first threshold value. The electrodeposition apparatus according to claim 1 , wherein the electrodeposition apparatus is controlled to be shut off. further comprising a second detection means for detecting the height of the liquid level in the first washing tank,
2. The control means controls the supply of the concentrated liquid to the first washing tank based on the detection results of the first detection means and the second detection means. Electrodeposition apparatus as described. The control means further controls to suppress or cut off supply of the concentrated liquid to the electrodeposition tank when the height of the liquid level in the first washing tank is below a third threshold value. ,
7. The concentrated liquid increased by suppressing or cutting off the supply of the concentrated liquid to the electrodeposition tank by the control means is supplied to the first washing tank. Electrodeposition equipment. a spray device for washing the object with water using a washing liquid in the first washing tank after the object is electrodeposited in the electrodeposition tank and before being washed in the first washing tank;
a return path for returning the washing liquid sprayed onto the object by the spray device and dropped to the first washing tank;
The electrodeposition apparatus according to claim 1 , further comprising the following. 9. The electrodeposition apparatus according to claim 8 , wherein the return path has an inclination so that the washing liquid sprayed onto the object and falling returns to the first washing tank by its own weight. The electrodeposition apparatus according to claim 1, wherein the filtration apparatus does not have a path for directly acquiring the liquid from the electrodeposition tank. The electrodeposition apparatus according to claim 1, further comprising a plurality of filtration devices that obtain liquid from at least one of the plurality of washing tanks and perform a filtration operation.

Images