JP2019131854A - Bath-liquid control device and bath-liquid control method for electrodeposition coating line - Google Patents

Abstract

To provide a bath-liquid control device and a bath-liquid control method for an electrodeposition coating line with low cost and high coating quality without causing any coating defects in an electrodeposition coating line even in a low production state.SOLUTION: A bath-liquid control device comprises: a first electrodeposition tank 2 for storing bath-liquid of electrodeposition paint; a first sub-tank 3 for storing bath-liquid overflowed from the first electrodeposition tank 2; a second electrodeposition tank 4 for storing the same bath-liquid of electrodeposition paint as that in the first electrodeposition tank 2; a second sub-tank 5 for storing bath-liquid overflowed from the second electrodeposition tank 4; a first liquid feeding unit 6 for supplying the bath-liquid in the first sub-tank 3 to the second electrodeposition tank 4; a second liquid feeding unit 7 for supplying the bath-liquid in the second sub-tank 5 to the first electrodeposition tank 2; a third liquid feeding unit 8 for supplying the bath-liquid in the first sub-tank 3 to the first electrodeposition tank 2 and circulating it; a fourth liquid feeding unit 9 for supplying the bath-liquid in the second sub-tank 5 to the second electrodeposition tank 4 and circulating it; and a control unit 10 for controlling the liquid feeding volume of each of the first to fourth liquid feeding units 6-9.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a bath liquid management apparatus and bath liquid management method for an electrodeposition coating line.

  Conventionally, electrodeposition coating is performed in a bath solution, which is a solution of water-soluble paint, with the object to be coated as the anode as the anode and the electrodeposition tank or separately installed electrode as the cathode, with a DC voltage between the two electrodes. Is applied to the surface of the object to be coated to form a coating film, which is suitable for mass production. Because it is used a lot.

  A typical prior art is described, for example, in Patent Document 1 as an electrodeposition bath management method and an electrodeposition coating system. In this prior art, the electrodeposition tank and the replenishment tank containing the electrodeposition coating composition are constantly stirred in order to prevent sedimentation and aggregation of a large amount of rust preventive pigment and extender pigment added to the electrodeposition coating composition. Although it is necessary, since the burden on the equipment and energy cost becomes large, for the purpose of reducing the energy cost for stirring, it consists of fatty acids, fatty acid derivatives, amine compounds and mixtures of one or more of them. The electrodeposition coating composition containing a pigment anti-settling agent selected from the group and a pigment, and having a small amount of precipitate even when left standing for a long time, It is proposed to circulate and stir the electrodeposition bath by taking out a part of the bath solution and returning it to the electrodeposition bath with a pump, and to stop the circulation pump when the electrodeposition coating is not performed. .

JP-A-2005-247992

  In recent years, in order to stabilize or improve productivity, there are cases where two electrodeposition coating lines for applying the same paint are used on the site of the same factory. Each of the two electrodeposition coating lines is equipped with an electrodeposition tank and a sub-tank for containing the bath liquid overflowed from the electrodeposition tank to remove air bubbles, replenishing paint, and adjusting paint composition. It is done.

  These electrodeposition coating lines do not always keep operating at almost constant productivity, but one electrodeposition coating line is operated in a high production state and the other electrodeposition coating line is operated in a low production state. The productivity required as a whole is ensured. In equipment using such a plurality of electrodeposition coating lines, the high-productivity electrodeposition coating line and the low-productivity electrodeposition coating line are the same even when the conventional technique described in Patent Document 1 is used. Although it is possible to reduce the amount of sediment generated in the bath liquid, the coating of the low productivity electrodeposition coating line deteriorates compared to the coating of the high productivity electrodeposition coating line. Along with the deterioration, defects such as coating defects occur. Also, if the low production situation is prolonged, the coating efficiency will decrease, so the amount of additives such as solvents to maintain the coating efficiency will increase excessively. Disposal of excess neutralized acid ions generated by the process, and cationic electrodeposition coatings will unnecessarily increase waste treatment wastewater loads such as waste of filtrate by ultrafiltration (UF) filtration and increase operating costs There's a problem.

  The object of the present invention is to prevent poor coating even in an electrodeposition coating line with a low production state, to suppress an increase in waste water load and an increase in operating cost, and to obtain high coating quality at low cost. To provide a bath liquid management apparatus and bath liquid management method for an electrodeposition coating line.

The bath liquid management device of the present invention stores a bath liquid of an electrodeposition paint, and a first electrodeposition tank for performing electrodeposition coating by immersing an object to be coated in the stored bath liquid;
A first sub-tank that stores the bath liquid overflowed from the first electrodeposition tank, the storage capacity of which is smaller than the storage capacity of the first electrodeposition tank;
A second electrodeposition tank in which a bath liquid of the same electrodeposition paint as the electrodeposition paint stored in the first electrodeposition tank is stored, and an object to be coated is immersed in the stored bath liquid to perform electrodeposition coating. When,
Storing the bath liquid overflowed from the second electrodeposition tank, a second sub tank having a storage capacity smaller than the storage capacity of the second electrodeposition tank;
A first liquid feeding section for supplying the bath liquid in the first sub tank to the second electrodeposition tank;
A second liquid feeding section for supplying the bath liquid in the second sub tank to the first electrodeposition tank;
A bath liquid management device for an electrodeposition coating line, comprising: a control unit that controls a liquid feeding amount of each of the first liquid feeding unit and the second liquid feeding unit.

  In the bath liquid management apparatus of the present invention, the control unit may determine a predetermined first liquid level H in which the liquid level of the bath liquid in the second sub tank is higher than the reference liquid level H0 from the predetermined reference liquid level H0. , The liquid feeding amount of the second liquid feeding part is increased in a state where the liquid feeding of the first liquid feeding part is maintained, and the liquid level of the bath liquid in the second sub tank is set to the reference liquid level. When a predetermined second liquid level L lower than the reference liquid level H0 is reached from H0, the liquid feeding amount of the second liquid feeding part is reduced while maintaining the liquid feeding of the first liquid feeding part. It is characterized by.

  In the bath liquid management apparatus of the present invention, the control unit may determine a third liquid level that is set in advance so that the liquid level of the bath liquid in the second sub-tank is higher than the first liquid level H from the first liquid level H. When Hmax is reached, the liquid feeding of the first liquid feeding unit is stopped.

  Further, in the bath liquid management apparatus of the present invention, the control unit may determine a fourth liquid level Lmin, which is a predetermined liquid level in which the liquid level of the bath liquid in the second sub-tank is lower than the second liquid level L from the second liquid level. When the value is reached, the liquid feeding amount of the first liquid feeding unit is increased.

Moreover, in the bath liquid management apparatus of the present invention, a first pipe connecting the first sub tank and the first electrodeposition tank,
A first circulation pump connected to the first pipe and sending the bath liquid in the first sub-tank to the first electrodeposition tank;
A second pipe connecting the second sub tank and the second electrodeposition tank;
A second circulation pump connected to the second pipe and feeding the bath liquid in the second sub tank to the second electrodeposition tank is further provided.

In the bath liquid management device of the present invention, the first electrodeposition tank has a storage capacity larger than the storage capacity of the second electrodeposition tank,
The first circulation pump has a larger capacity than the second circulation pump,
The first liquid feeding section includes a third pipe that connects the first pipe and the second electrodeposition tank, and a flow rate adjustment valve that is connected to the third pipe.
The second liquid feeding unit is connected to the fourth pipe for connecting the second pipe and the first electrodeposition tank, and the liquid feed for feeding the bath liquid in the second sub tank. A pump, and
The control unit adjusts a liquid feeding amount of the first liquid feeding unit by controlling an opening degree of the flow rate adjusting valve, and controls a discharge amount of the liquid feeding pump, thereby controlling the second liquid feeding unit. It is characterized by adjusting the liquid feeding amount of the part.

The bath liquid management method of the present invention includes a first electrodeposition tank in which a bath liquid of an electrodeposition paint is stored, and an object to be coated is immersed in the stored bath liquid to perform electrodeposition coating.
A first sub-tank that stores the bath liquid overflowed from the first electrodeposition tank, the storage capacity of which is smaller than the storage capacity of the first electrodeposition tank;
A second electrodeposition tank in which a bath liquid of the same electrodeposition paint as the electrodeposition paint stored in the first electrodeposition tank is stored, and an object to be coated is immersed in the stored bath liquid to perform electrodeposition coating. When,
A bath liquid management method for an electrodeposition coating line, comprising: a second sub tank having a storage capacity smaller than a storage capacity of the second electrodeposition tank, storing the bath liquid overflowed from the second electrodeposition tank. And
Electrodeposition coating characterized in that the bath liquid in the first sub-tank is sent to the second electrodeposition tank, and the bath liquid in the second sub-tank is sent to the first electrodeposition tank. This is a line bath liquid management method.

  In the bath liquid management method of the present invention, when the liquid level of the bath liquid in the second sub-tank reaches a predetermined first liquid level H higher than the reference liquid level H0 from the predetermined reference liquid level H0, While maintaining the liquid feeding of the first liquid feeding part, the liquid feeding amount of the second liquid feeding part is increased, and the liquid level of the bath liquid in the second sub-tank is changed from the reference liquid level H0 to the reference liquid. When a predetermined second liquid level L lower than the level H0 is reached, the liquid feeding amount of the second liquid feeding part is reduced while maintaining the liquid feeding of the first liquid feeding part.

  In the bath liquid management method of the present invention, when the liquid level of the bath liquid in the second sub-tank reaches a predetermined third liquid level Hmax higher than the first liquid level H from the first liquid level H, The liquid feeding of the first liquid feeding unit is stopped.

  In the bath liquid management method of the present invention, when the liquid level of the bath liquid in the second sub-tank reaches a predetermined fourth liquid level Lmin lower than the second liquid level L from the second liquid level, The liquid feeding amount of the second liquid feeding unit is increased.

  According to the present invention relating to the bath liquid management apparatus, a first electrodeposition tank, a first sub-tank having a storage capacity smaller than the storage capacity of the first electrodeposition tank, and an electrodeposition paint stored in the first electrodeposition tank A second electrodeposition tank in which a bath solution of the same electrodeposition paint is stored, and a second subtank having a storage capacity smaller than the storage capacity of the second electrodeposition tank, Since the bath liquid in the deposition tank is supplied to the second electrodeposition tank, and the bath liquid in the second electrodeposition tank is supplied to the first electrodeposition tank by the second liquid feeding unit, the first electrodeposition tank and the second electrodeposition tank The bath liquid is exchanged with the electrodeposition bath. As a result, the quality of the bath liquid stored between the first and second electrodeposition tanks is kept the same, and paint deterioration and pigment settling are reduced as in the prior art, so that no coating failure occurs and waste water is discharged. An increase in load and an increase in operating cost can be suppressed, and high coating quality can be obtained at low cost.

  Further, according to the present invention, when the liquid level of the bath liquid in the second sub-tank reaches the predetermined first liquid level H higher than the reference liquid level H0 from the predetermined reference liquid level H0, In the state where the liquid feeding of the first liquid feeding part is maintained, the liquid feeding amount of the second liquid feeding part is increased, and the liquid level of the bath liquid in the two sub tanks is changed from the reference liquid level H0 to the reference liquid level H0. When the low second liquid level L is reached, the liquid feeding amount of the second liquid feeding unit is reduced while maintaining the liquid feeding of the first liquid feeding unit, so that the bath liquid in the second sub-tank is the first. It is maintained between the liquid level H and the second liquid level L, whereby an appropriate liquid amount can be maintained regardless of the production amount.

  Further, according to the present invention, when the liquid level of the bath liquid in the second sub-tank reaches the predetermined third liquid level Hmax higher than the first liquid level H from the first liquid level, Since the liquid feeding of the liquid feeding unit is stopped, it is possible to prevent the bath liquid from being excessively stored in the second sub tank.

  Further, according to the present invention, when the liquid level of the bath liquid in the second sub-tank reaches the predetermined fourth liquid level Lmin lower than the second liquid level L from the second liquid level L, Since the liquid feeding amount of the two liquid feeding units is increased, it is possible to prevent the bath liquid in the second sub tank from being excessively reduced.

  According to the present invention, the first pipe connecting the first sub tank and the first electrodeposition tank, and the first pipe interposed between the first pipe and the bath liquid in the first sub tank are sent to the first electrodeposition tank. 1 circulation pump, 2nd piping which connects the 2nd sub tank and the 2nd electrodeposition tank, and 2nd circulation which is connected to the 2nd piping and sends the bath liquid in the 2nd sub tank to the 2nd electrodeposition tank Since the pump is provided, the bath liquid is circulated between the first sub-tank and the first electrodeposition tank and between the second sub-tank and the second electrodeposition tank, and components such as pigments having a large specific gravity may settle. It is prevented and an appropriate dispersion state can be maintained.

  According to the invention, the storage capacity of the first electrodeposition tank is larger than the storage capacity of the second electrodeposition tank, and the first circulation pump has a larger capacity than the second circulation pump, and the first liquid feeding section Includes a third pipe connecting the first pipe and the second electrodeposition tank, and a flow rate adjusting valve connected to the third pipe, and the second liquid feeding section further includes the second sub tank and the first electrodeposition. A fourth pipe for connecting the tank and a liquid feed pump connected to the fourth pipe for feeding the bath liquid in the second sub-tank, and the control unit controls the opening of the flow rate adjustment valve. The liquid supply amount of the second liquid supply unit is adjusted by adjusting the liquid supply amount of the first liquid supply unit and controlling the discharge amount of the liquid supply pump. As a result, a part of the bath liquid in the first sub-tank is sent to the second electrodeposition tank at an appropriate flow rate according to the opening of the flow control valve, and the liquid is exchanged at a lower operating cost than the liquid feed pump. It becomes possible.

  According to the present invention relating to the bath liquid management method, the first liquid feeding section supplies the bath liquid in the first sub tank to the second electrodeposition tank, and the second liquid feeding section supplies the bath liquid in the second sub tank to the second liquid tank. Since it is supplied to one electrodeposition tank, the bath liquid is exchanged between the first electrodeposition tank and the second electrodeposition tank, and the bath liquid is highly productive even in a low electrodeposition coating line. It is replaced at the same replacement rate as the electrodeposition coating line, so that the quality of the bath solution stored between the first and second electrodeposition tanks is kept the same. Thus, coating failure does not occur, an increase in wastewater load and an increase in operating cost can be suppressed, and high coating quality can be obtained at low cost.

  According to the invention, when the liquid level of the bath liquid in the second sub-tank reaches the predetermined first liquid level H higher than the predetermined reference liquid level H0 from the predetermined reference liquid level H0, the first liquid feeding section. When the liquid supply amount of the second liquid supply unit is increased while the liquid supply of the second sub-tank is maintained and the liquid level of the bath liquid in the two sub tanks reaches a predetermined second liquid level L lower than the reference liquid level H0. Since the liquid feeding amount of the second liquid feeding unit is reduced while the liquid feeding of the first liquid feeding unit is maintained, the bath liquid in the second sub tank is changed between the first liquid level H and the second liquid level L. Thus, an appropriate amount of liquid can be maintained regardless of the production amount.

  Further, according to the present invention, when the liquid level of the bath liquid in the second sub-tank reaches a predetermined third liquid level Hmax higher than the first liquid level H, the liquid feeding of the first liquid feeding unit is stopped. It is possible to prevent the bath liquid from being excessively stored in the second sub tank.

  According to the invention, when the liquid level of the bath liquid in the second sub-tank reaches a predetermined fourth liquid level Lmin lower than the second liquid level L, the liquid supply amount of the first liquid supply unit is increased. Therefore, it is possible to prevent the bath liquid in the second sub tank from being excessively reduced.

It is a systematic diagram which shows the structure of the bath liquid management apparatus 1 of the electrodeposition coating line of one Embodiment of this invention. It is a block diagram which shows typically the control part with which the bath liquid management apparatus 1 is provided, and its control object. FIG. 3A is a graph showing a change in the liquid level of the bath liquid in the second sub tank 5, FIG. 3A shows a change when the liquid level is lowered after rising, and FIG. 3B is a graph showing a rise when the liquid level is lowered. The change when it is done is shown. 3 is a flowchart for explaining an operation of a control unit 10.

  FIG. 1 is a system diagram showing a configuration of a bath liquid management apparatus 1 of an electrodeposition coating line according to an embodiment of the present invention. FIG. 2 schematically shows a control unit provided in the bath liquid management apparatus 1 and its control target. It is a block diagram shown in FIG. In addition, the case where this invention which concerns on the bath liquid management method is implemented by the bath liquid management apparatus 1 of this embodiment is demonstrated below. The bath liquid management apparatus 1 of this embodiment is used for electrodeposition coating of objects to be coated such as aluminum building materials and automobile bodies. The electrodeposition paint may be either a cationic electrodeposition paint using a cationic resin as a main resin or an anion electrodeposition paint using an anion resin as a main resin. Further, the pigment may contain an inorganic pigment that has a high specific gravity and is likely to precipitate.

  The bath liquid management device 1 stores a bath liquid of an electrodeposition paint, and includes a first electrodeposition tank 2 that performs electrodeposition coating by immersing an object to be coated in the stored bath liquid, and a first electrodeposition tank 2. A first sub-tank 3 having a capacity smaller than that of the first electrodeposition tank 2 for storing the overflowed bath liquid, and a bath liquid of the same electrodeposition paint as the electrodeposition paint stored in the first electrodeposition tank 2 are stored. A second electrodeposition tank 4 for performing electrodeposition coating by immersing an object in the stored bath liquid, and a second electrodeposition tank 4 for storing the bath liquid overflowed from the second electrodeposition tank 4 A second sub-tank 5 having a smaller capacity, a first liquid feeding section 6 for supplying the bath liquid in the first sub-tank 3 to the second electrodeposition tank 4, and a bath liquid in the second sub-tank 5; A second liquid feeding section 7 for supplying the first electrodeposition tank 2, a third liquid feeding section 8 for supplying and circulating the bath liquid in the first sub-tank 3 to the first electrodeposition tank 2; S A fourth liquid feeding section 9 for supplying and circulating the bath liquid in the tank 5 to the second electrodeposition tank 4, and a control section 10 for controlling the liquid feeding amounts of the first to fourth liquid feeding sections 6 to 9, respectively. Is provided.

  The third liquid delivery unit 8 is interposed between the first pipe 11 that connects the first subtank 3 and the first electrodeposition tank 2, and the first pipe 11, and the bath solution in the first subtank 3 is first electrodeposited. A first liquid feeding pump P1 for feeding liquid to the tank 2; The 4th liquid feeding part 9 is interposed in the 2nd piping 12 which connects the 2nd subtank 5 and the 2nd electrodeposition tank 4, and the 2nd piping 12, and the bath solution in the 2nd subtank 5 is used for the 2nd electrodeposition. A second liquid feeding pump P2 for feeding liquid to the tank 4;

  A filter 23 is interposed in the first pipe 11 on the downstream side of the first liquid feed pump P1. Further, a filter 24 is interposed in the first pipe 11 on the downstream side of the second liquid feeding pump P2. These filters 23 and 24 are realized by a filter filtration device that filters the bath liquid with a filter accuracy of, for example, 1 μm to 100 μm. The filter 13 is filtered by passing through the bottom sediment of the bath liquid near the bottom of the first sub-tank 3 to remove foreign substances such as aggregates and dust in the bath liquid, and again passes through the first pipe 11 to obtain a clean bath. The liquid is returned into the first electrodeposition tank 2. In addition, the filter 24 is filtered by passing the bottom of the bath liquid near the bottom of the second sub tank 5 in the same manner as the filter 23 described above to remove foreign substances such as aggregates and dust in the bath liquid, and again. The clean bath liquid is returned to the second electrodeposition tank 4 through the second pipe 12.

  The capacity | capacitance of the 1st electrodeposition tank 2 is larger than the 2nd electrodeposition tank 4, and the capacity | capacitance of the 1st circulation pump P1 is larger than the 2nd liquid feeding pump P2. As an example, the first electrodeposition tank 2 is a main tank (or main tank) of the electrodeposition coating line A with high productivity, and the bath liquid is fed at a rate of, for example, about 180 m <3> / hr. Is done. The second electrodeposition tank 4 is a main tank (or main tank) of the electrodeposition coating line B with low productivity, and the bath liquid is fed at, for example, about 60 m <3> / hr to perform electrodeposition coating. These first and second electrodeposition tanks 2 and 4 are replenished with replenishing paint from replenishing tanks 19 and 20, respectively.

  The first liquid feeding section 6 has a first end connected between the first liquid feeding pump P1 of the first pipe 11 and the filter 23, and the other end connected to the lower portion of the second electrodeposition tank 4. A pipe 13 and a flow rate adjusting valve V1 interposed in the third pipe 13 are provided. The second liquid feeding unit 7 has a first end connected between the second liquid feeding pump P <b> 2 of the second pipe 12 and the filter 24, and the other end connected to the lower portion of the first electrodeposition tank 2. A pipe 14 and a flow rate adjustment valve V4 interposed in the fourth pipe 14 are provided. One end of the fifth pipe 15 is connected between the first liquid delivery pump P1 of the first pipe 11 and the bottom of the first sub tank 3, and the other end of the fifth pipe 15 is connected to the second electrodeposition tank. 4 is connected to the lower part. A third liquid feed pump P3 and a flow rate adjustment valve V3 are interposed in the fifth pipe 15, and the flow rate of the bath liquid discharged from the third liquid feed pump P3 is adjusted by the flow rate adjustment valve V3. One end of the sixth pipe 16 is connected between the bottom of the second sub tank 5 of the second pipe 12 and the second liquid feeding pump P2, and the other end of the sixth pipe 16 is the first electrodeposition tank. 2 is connected to the lower part. The sixth pipe 16 is provided with a fourth liquid feed pump P4 and a flow rate adjusting valve V6, and the flow rate of the bath liquid discharged from the fourth liquid feed pump P4 is adjusted by the flow rate adjusting valve V6. One end of the seventh pipe 17 is connected between the filter 23 of the first pipe 11 and the bottom of the first electrodeposition tank 2, and the other end of the seventh pipe 17 is connected to the lower part of the second electrodeposition tank 4. Is done. A flow rate adjusting valve V2 is interposed in the seventh pipe 17, and the flow rate of the bath liquid discharged from the first liquid feeding pump P1 and passing through the filter 23 is adjusted by the flow rate adjusting valve V2. One end of the eighth pipe 18 is connected between the filter 24 of the second pipe 12 and the bottom of the second electrodeposition tank 4, and the other end of the eighth pipe 18 is connected to the lower part of the first electrodeposition tank 2. Is done. A flow rate adjusting valve V5 is interposed in the eighth pipe 18, and the flow rate of the bath liquid discharged from the second liquid feeding pump P2 and passing through the filter 24 is adjusted by the flow rate adjusting valve V5. Each flow control valve V1-V6 may be implement | achieved by the motor operated valve, and may be implement | achieved by the solenoid valve. The first to fourth liquid feeding pumps P1 to P4 and the flow rate adjusting valves V1 to V6 are controlled by the control unit 10. The control unit 10 controls the liquid feed amount of the first to fourth liquid feed pumps P1 to P4 and the opening degree of each flow rate adjusting valve V1 to V6, and may be realized by, for example, a sequence control device or realized by a computer. May be.

  The first sub tank 3 and the second sub tank 5 are respectively provided with liquid level gauges 21 and 22 in order to measure the liquid level of the stored bath liquid. These liquid level gauges 21 and 22 are realized by, for example, a differential pressure type level sensor, and a signal indicating a liquid level corresponding to the liquid level of the stored bath liquid is output. The signal indicating the liquid level is a control unit. 10 is input. In another embodiment, the liquid level gauge 22 may be provided only in the second sub tank 5, and the control unit 10 may be configured to perform a control operation in response to a signal indicating the liquid level from the liquid level gauge 22.

  FIG. 3 is a graph showing a change in the liquid level of the bath liquid in the second sub-tank 5, FIG. 3 (a) shows a change when the liquid level drops after rising, and FIG. 3 (b) shows a liquid level. It shows the change when going up after going down. FIG. 4 is a flowchart for explaining the operation of the control unit 10. In the present embodiment, the first electrodeposition coating line A operates at a high production amount, the second electrodeposition coating line B operates at a low production amount, and the first and third liquid feed pumps P1, P3 are the first and This is a large-capacity pump having a sufficient discharge output for liquid exchange between the second electrodeposition coating lines A and B. The second and fourth liquid feed pumps P2 and P4 are the first and third liquid feed pumps P1 and P1, respectively. A case where the pump is a small-capacity pump having a relatively small discharge output compared to the discharge output of P3 will be described. In step s1, the control operation of the first to fourth liquid feed pumps P1 to P4 and the flow rate adjusting valves V1 to V6 by the control unit 10 is started. A signal indicating the liquid level of the bath liquid in the second sub-tanks 3 and 5 is input. In a state where signals indicating the liquid levels from the liquid level gauges 21 and 22 are input to the control unit 10, the control unit 10 inputs the liquid level in the second sub tank 5 from the liquid level gauges 21 and 22. The determination is made in response to the signal indicating the liquid level, and when the liquid level of the bath liquid in the second sub tank 5 reaches the predetermined first liquid level H from the predetermined reference liquid level H0 in step s2, step The process proceeds to s3, and while the liquid feeding of the first liquid feeding unit 6 is maintained, the opening amount of the flow rate adjusting valve V1 is decreased to reduce the liquid feeding amount of the first liquid feeding unit 6, and the flow rate regulating valve V4. Is increased to increase the amount of liquid fed by the second liquid feeding unit 7.

  In step s2, if the liquid level in the second sub-tank 5 is between the reference liquid level H0 and the first liquid level H, that is, less than the first liquid level H, the process proceeds to step s4, and the flow rate adjusting valves V1, V4. It is determined whether or not the liquid level in the second sub tank 5 is equal to or higher than the third liquid level Hmax while maintaining a steady operation without changing the opening degree. If the liquid level of the bath liquid in the second sub tank 5 reaches the predetermined third liquid level Hmax from the first liquid level H and becomes equal to or higher than the third liquid level Hmax higher than the first liquid level H, the process proceeds to step s5. Then, the flow rate adjusting valve V1 is closed, and the liquid feeding to the first liquid feeding unit 6 is stopped. Further, if it is between the first liquid level H and the third liquid level Hmax, that is, less than the third liquid level Hmax, the process proceeds to the next step s6.

  In step s6, it is determined whether or not the liquid level in the second sub-tank 5 is equal to or lower than a predetermined second liquid level L lower than the first liquid level H from the reference liquid level H0. When the liquid level in the second sub-tank 5 reaches the second liquid level L from the reference liquid level H0 and becomes equal to or lower than the second liquid level L, the process proceeds to step s7 to increase the opening degree of the flow rate adjusting valve V1 and the flow rate. The amount of the bath liquid supplied to the second sub-tank 5 is increased by decreasing the opening degree of the regulating valve V4.

  In step s6, if the liquid level in the second sub-tank 5 further decreases from the second liquid level L, the process proceeds to the next step s8, is the liquid level Hmax lower than the second liquid level L? It is determined whether or not. If the liquid level reaches the third liquid level Hmax and is equal to or lower than the third liquid level Hmax, the process proceeds to step s9, the opening degree of the flow rate adjustment valve V1 is increased, the flow rate adjustment valve V4 is closed, and the second liquid supply unit 7 is increased, and the amount of liquid supplied to the second sub tank 5 is increased.

  As described above, according to the bath liquid management apparatus 1 of the present embodiment, the first electrodeposition tank 2, the first sub tank 3 having a smaller capacity than the first electrodeposition tank, and the first electrodeposition tank 2 are stored. A second electrodeposition tank 4 in which a bath solution of the same electrodeposition paint as the electrodeposition paint to be stored is stored, and a second sub tank 5 having a capacity smaller than that of the second electrodeposition tank 4, 6, the bath liquid in the first sub tank 3 is supplied to the second electrodeposition tank 4, and the bath liquid in the second sub tank 5 is supplied to the first electrodeposition tank 2 by the second liquid feeding unit 7. The bath liquid is exchanged between the electrodeposition tank 2 and the second electrodeposition tank 4, and the bath liquid is replaced with a high replacement rate even in the low electrodeposition coating line B in the production state. Maintains the same quality of the bath solution stored between the second electrodeposition tanks 2 and 4 and reduces paint deterioration and pigment settling as in the prior art, so that no coating failure occurs. Suppressing an increase and increase the operating costs of the waste water load, it is possible to obtain a high coating quality at low cost. Conventionally, since the bath liquid in the second electrodeposition tank 4 and the second sub tank 5 is hydrolyzed, periodic ion exchange is required and 400 to 1200 kg of the adjustment solvent is required. According to the form, the adjustment solvent was 0 to 40 kg, and it was confirmed that the adjustment solvent was substantially reduced and the periodic ion exchange became unnecessary.

  When the liquid level of the bath liquid in the second sub-tank 5 reaches the first liquid level H set in advance, the control unit 10 maintains the liquid supply of the first liquid supply part 6 and maintains the second liquid supply part. When the liquid level of the bath liquid in the two sub tanks 5 reaches a predetermined second liquid level L that is lower than the first liquid level H, the liquid feeding amount of the first liquid feeding unit 6 is increased. In this state, the liquid feeding amount of the second liquid feeding unit 7 is reduced, so that the bath liquid in the second sub-tank 5 is kept between the first liquid level H and the second liquid level L, thereby producing An appropriate amount of liquid can be maintained regardless of the amount.

  When the liquid level of the bath liquid in the second subtank 5 reaches a predetermined third liquid level Hmax higher than the first liquid level H, the control unit 10 stops the liquid supply of the first liquid supply unit 6. Therefore, it is possible to prevent the bath liquid from being excessively stored in the second sub tank 5.

  When the liquid level of the bath liquid in the second sub-tank 5 reaches a predetermined fourth liquid level Lmin that is lower than the second liquid level L, the control unit 10 increases the liquid supply amount of the second liquid supply unit 6. Therefore, it is possible to prevent the bath liquid in the second sub tank 5 from being excessively reduced.

  Further, a first pipe 11 connecting the first sub tank 3 and the first electrodeposition tank 2 is interposed between the first pipe 11 and the bath liquid in the first sub tank 3 to the first electrodeposition tank 2. A first liquid feed pump P1 as a first circulation pump, a second pipe 12 connecting the second sub tank 5 and the second electrodeposition tank 4, and a bath in the second sub tank 5 interposed in the second pipe 12 Since the second liquid feeding pump P2 as a second circulation pump for feeding the liquid to the second electrodeposition tank 4 is provided, the first subtank 3 and the first electrodeposition tank 2 and the second subtank 5 The bath liquid is circulated between the two electrodeposition tanks 4 to prevent sedimentation of components having a large specific gravity, such as pigments, and an appropriate dispersion state can be maintained.

  The first electrodeposition tank 2 has a larger capacity than the second electrodeposition tank 4, the first liquid feed pump P1 has a larger capacity than the second liquid feed pump P2, and the first liquid feed section 6 has a first capacity. The second liquid feeding unit 7 includes a third pipe 13 that connects the first pipe 11 and the second electrodeposition tank 4, and a flow rate adjustment valve V <b> 1 interposed in the third pipe 13. 4th piping 14 which connects 1 subtank, and 2nd liquid feeding pump P2 which intervenes in 4th piping 14 and sends the bath liquid in the 2nd subtank 5 are included. The control unit 10 adjusts the liquid feeding amount of the first liquid feeding unit 6 by controlling the opening degree of the flow rate adjusting valve V1, and controls the discharge amount of the third liquid feeding pump P3, thereby controlling the second feeding amount. The liquid feeding amount of the liquid part 7 is adjusted. Thereby, a part of the bath liquid in the first sub-tank 3 is sent to the second electrodeposition tank 4 at an appropriate flow rate according to the opening degree of the flow rate adjustment valve V1, and a pump is used instead of the flow rate adjustment valve V1. As a result, the liquid can be exchanged at a lower operating cost.

  In the above-described embodiment, the liquid is mainly transferred to the second electrodeposition tank 4 by the third pipe 13 branched from the first pipe 11 for supplying and circulating the bath liquid from the first subtank 3 to the first electrodeposition tank 2. A first liquid feeding section 6 for adjusting the flow rate of the bath liquid to the flow rate adjusting valve V1, and a fourth pipe branched from the second pipe 12 for supplying and circulating the bath liquid from the second sub tank 5 to the second electrodeposition tank 4. The second electrodeposition tank of the second electrodeposition coating line B having a low operating rate by the second liquid feeding part 7 that adjusts the flow rate of the bath liquid transferred to the first electrodeposition tank 2 by the flow rate adjusting valve V2. 4 and the bath solution in the second sub-tank 5 are replaced at a high replacement rate, so that the properties of the paint on the first electrodeposition coating line A and the paint on the second electrodeposition coating line B are kept the same or substantially the same. Although the configuration has been described, as another embodiment of the present invention, the above-described first embodiment is described. In place of the second liquid feeding sections 6 and 7, the flow rate of the bath liquid transferred by the fifth pipe 15 branched from the first pipe 11 is adjusted by the third liquid feed pump P3 and the flow rate adjusting valve V3. A configuration in which the flow rate of the bath liquid transferred by the sixth pipe 16 branched from the second pipe 12 is adjusted by the fourth liquid feed pump P4 and the flow rate adjusting valve V6 is used as the first liquid feed section. Or the structure which adjusts the flow volume of the bath liquid transferred by the 7th piping 17 branched from the 1st piping 11 via the filter 25 by the 1st liquid feeding pump P1 and the flow volume adjustment valve V2 is made into the 1st liquid feeding part. A configuration in which the flow rate of the bath liquid transferred from the second pipe 12 through the eighth pipe 18 branched through the filter 26 is adjusted by the second liquid feed pump P2 and the flow rate adjusting valve V5 is used as the second liquid feed section. Like Also good. Even when such a configuration is adopted, the same effect as that obtained when the first and second liquid feeding units 6 and 7 are used can be achieved.

DESCRIPTION OF SYMBOLS 1 Bath liquid management apparatus 2 1st electrodeposition tank 3 1st subtank 4 2nd electrodeposition tank 5 2nd subtank 6 1st liquid feeding part 7 2nd liquid feeding part 8 3rd liquid feeding part 9 4th liquid feeding part 10 Control part 11 1st piping 12 2nd piping 13 3rd piping 14 4th piping 15 5th piping 16 6th piping 17 7th piping 18 8th piping 19,20 Supply tank 21,22 Liquid level gauge 23,24 Filter P1 1st liquid pump P2 2nd liquid pump P3 3rd liquid pump P4 4th liquid pump V1-V6 Flow control valve

Claims (10)

A first electrodeposition tank in which a bath liquid of an electrodeposition paint is stored, and an object to be coated is immersed in the stored bath liquid to perform electrodeposition coating;
A first sub-tank that stores the bath liquid overflowed from the first electrodeposition tank, the storage capacity of which is smaller than the storage capacity of the first electrodeposition tank;
A second electrodeposition tank in which a bath liquid of the same electrodeposition paint as the electrodeposition paint stored in the first electrodeposition tank is stored, and an object to be coated is immersed in the stored bath liquid to perform electrodeposition coating. When,
Storing the bath liquid overflowed from the second electrodeposition tank, a second sub tank having a storage capacity smaller than the storage capacity of the second electrodeposition tank;
A first liquid feeding section for supplying the bath liquid in the first sub tank to the second electrodeposition tank;
A second liquid feeding section for supplying the bath liquid in the second sub tank to the first electrodeposition tank;
And a control unit for controlling the amount of liquid fed to each of the first liquid feeding unit and the second liquid feeding unit.   When the liquid level of the bath liquid in the second subtank reaches a predetermined first liquid level H higher than the reference liquid level H0 from the predetermined reference liquid level H0, the control unit In the state where the liquid feeding is maintained, the liquid feeding amount of the second liquid feeding unit is increased, and the liquid level of the bath liquid in the second sub tank is lower than the reference liquid level H0 from the reference liquid level H0. 2. The liquid feeding amount of the second liquid feeding unit is reduced when the liquid level is lowered to a predetermined second liquid level L while the liquid feeding of the first liquid feeding unit is maintained. Bath fluid management device for electrodeposition coating line.   When the liquid level of the bath liquid in the second sub-tank reaches a predetermined third liquid level Hmax higher than the first liquid level H from the first liquid level H, the control unit supplies the first liquid supply. 3. The bath liquid management apparatus for an electrodeposition coating line according to claim 2, wherein the liquid feeding of the part is stopped.   When the liquid level of the bath liquid in the second sub-tank falls from the second liquid level L to a predetermined fourth liquid level Lmin that is lower than the second liquid level L, the control unit performs the first liquid feeding. 4. The bath liquid management apparatus for an electrodeposition coating line according to claim 2, wherein the liquid feeding amount of the part is increased. A first pipe connecting the first sub tank and the first electrodeposition tank;
A first circulation pump connected to the first pipe and sending the bath liquid in the first sub-tank to the first electrodeposition tank;
A second pipe connecting the second sub tank and the second electrodeposition tank;
5. The apparatus according to claim 1, further comprising: a second circulation pump that is connected to the second pipe and feeds the bath liquid in the second sub tank to the second electrodeposition tank. Bath fluid management device for electrodeposition coating line. The first electrodeposition tank has a storage capacity larger than the storage capacity of the second electrodeposition tank,
The first circulation pump has a capacity larger than the capacity of the second circulation pump,
The first liquid feeding part includes a third pipe connecting the first pipe and the second electrodeposition tank, and a flow rate adjusting valve connected to the third pipe,
The second liquid feeding unit is connected to the fourth pipe for connecting the second pipe and the first electrodeposition tank, and the liquid feed for feeding the bath liquid in the second sub tank. A pump, and
The control unit adjusts a liquid feeding amount of the first liquid feeding unit by controlling an opening degree of the flow rate adjusting valve, and controls a discharge amount of the liquid feeding pump, thereby controlling the second liquid feeding unit. The bath liquid management device for an electrodeposition coating line according to claim 5, wherein the liquid feeding amount of the part is adjusted. A first electrodeposition tank in which a bath liquid of an electrodeposition paint is stored, and an object to be coated is immersed in the stored bath liquid to perform electrodeposition coating;
A first sub-tank that stores the bath liquid overflowed from the first electrodeposition tank, the storage capacity of which is smaller than the storage capacity of the first electrodeposition tank;
A second electrodeposition tank in which a bath liquid of the same electrodeposition paint as the electrodeposition paint stored in the first electrodeposition tank is stored, and an object to be coated is immersed in the stored bath liquid to perform electrodeposition coating. When,
A bath liquid management method for an electrodeposition coating line, comprising: a second sub tank having a storage capacity smaller than a storage capacity of the second electrodeposition tank, storing the bath liquid overflowed from the second electrodeposition tank. And
Electrodeposition coating characterized in that the bath liquid in the first sub-tank is sent to the second electrodeposition tank, and the bath liquid in the second sub-tank is sent to the first electrodeposition tank. Line bath liquid management method.   When the liquid level of the bath liquid in the second subtank reaches a predetermined first liquid level H higher than the reference liquid level H0 from the predetermined reference liquid level H0, the liquid supply of the first liquid supply unit is maintained. In this state, the liquid supply amount of the second liquid supply unit is increased, and the liquid level of the bath liquid in the second sub-tank is predetermined second liquid lower than the reference liquid level H0 from the reference liquid level H0. 8. The electrodeposition coating line according to claim 7, wherein the liquid deposition amount of the second liquid feeding section is reduced in a state where the liquid feeding of the first liquid feeding section is maintained when the level is lowered to L. Bath liquid management method.   When the liquid level of the bath liquid in the second sub-tank reaches a predetermined third liquid level Hmax higher than the first liquid level H from the first liquid level H, the liquid feeding of the first liquid feeding unit is performed. The bath liquid management method for an electrodeposition coating line according to claim 8, wherein the bath liquid is stopped. When the liquid level of the bath liquid in the second sub-tank falls from the second liquid level L to a predetermined fourth liquid level Lmin lower than the second liquid level L, the liquid feeding amount of the first liquid feeding unit The bath liquid management method for an electrodeposition coating line according to claim 8 or 9, wherein

Images