JPH11197586A - Lightweight foreign matter removing method and coating cleaner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide the method for removing lightweight foreign matter by which such refuse as a metal powder is efficiently removed and to provide a coating cleaner. SOLUTION: This coating cleaner is provided with a chamber 11 through which a material 13 to be cleaned is passed, the tanks 12 and 14 for collecting a cleaning soln. discharged in the chamber through an opening 112 formed in the floor 111 of the chamber and the circulating line 15 for sucking the cleaning soln. collected in the tank and discharging the soln. on the material passing through the chamber. The cleaner is further provided with a magnetic field impressing means 16 for impressing a magnetic field on the floor of the chamber and turning off the magnetic field and a nozzle 17 furnished on the floor of the chamber and discharging the cleaning soln. toward the opening.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for removing lightweight foreign matter which are preferably applied to a pretreatment cleaning step of a coating line, and more particularly to a method for removing lightweight foreign matter excellent in removing lightweight dust such as iron powder. The present invention relates to a removing method and a paint cleaning device.

[0002]

2. Description of the Related Art In a production line of an automobile body, a white body after a welding process is subjected to various cleaning and degreasing processes such as pre-cleaning, washing, hot water washing, preliminary degreasing, and degreasing, and then a zinc phosphate film is formed on the body surface. Is sent to a chemical conversion treatment step for forming a chemical conversion film consisting of, and thereafter, an electrodeposition coating as an undercoat is applied.

In such a pretreatment / electrodeposition process, the white body is subjected to various surface treatments while being continuously and constantly conveyed by an overhead conveyor while being mounted on a hanger.

By the way, in a welding line, which is a pre-process of a painting line, a body panel is joined by spot welding or arc welding and assembled, so that iron powder such as spatter at the time of spot welding adheres to an automobile body. Be brought to As described above, a multi-step cleaning step is provided in a step before the chemical conversion step in order to clean such foreign substances. In particular, as a method of removing metallic foreign matter such as iron powder, a method using a magnet, a method using a rotary separator, and the like have been proposed in addition to providing a filter in a circulation system.

For example, in a cleaning apparatus 1 shown in FIG. 8, a cleaning liquid discharged from a chamber 11 is temporarily stored in a settling tank 12, and then the settling tank 12 and the weir 1
The supernatant liquid is caused to overflow to the spray tank 14 provided through the nozzle 3 to collect dust G such as iron powder at the bottom of the settling tank 12.

[0006]

By the way, a lot of dust such as iron powder brought into the painting line includes very light ones. It takes a considerable amount of time to settle. That is, if the liquid flow from the settling tank 12 to the spray tank 14, particularly the rising flow velocity V of the settling tank 12 indicated by an arrow in the figure is larger than the sedimentation speed of dust, the liquid overflows to the spray tank 14 before settling. Therefore, it is necessary to maintain the liquid flow velocity in the settling tank 12 lower than the sedimentation velocity of dust.

For this purpose, it is conceivable to increase the capacity of the settling tank 12, but there is a limit to increasing the capacity of the settling tank 12 due to the space of the coating line.

[0008] However, if the fine and lightweight iron powder cannot be completely washed off, the iron powder is carried into the chemical conversion treatment tank while adhering to the body, and the iron powder adhering to the steel sheet surface is converted into the chemical conversion film. It is buried, and an electrodeposition coating film is formed thereon, resulting in a coating film defect such as dust.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems of the prior art, and has as its object to provide a method for removing lightweight foreign matter and a paint cleaning apparatus capable of efficiently removing dust such as metal powder. And

[0010]

(1) According to a first aspect of the present invention, a magnetic field is applied to a cleaning liquid sprayed onto an object to be cleaned by applying a magnetic field for a predetermined time. After magnetizing the magnetic foreign matter contained in the above, a method for removing the light foreign matter is provided, wherein the magnetized foreign matter is collected and settled.

[0011] The cleaning liquid sprayed on the object to be cleaned contains various foreign substances of various sizes. Particularly, lightweight foreign substances have a low sedimentation speed due to their own weight, and therefore sedimentation is trapped in a circulation system having a certain flow velocity. It is difficult to do. However, in the method for removing light foreign matter according to the present invention, the magnetic foreign matter contained in the washed foreign matter is magnetized, so that even the light foreign matter is attracted to each other to form a lump having a certain weight. Then, if the aggregated foreign matter is settled and settled,
Even if lightweight foreign matter is contained, it can be efficiently removed.

(2) In order to achieve the above object, according to a second aspect of the present invention, a chamber through which an object to be cleaned passes, and a cleaning liquid discharged in the chamber are placed on a floor surface of the chamber. A tank for collecting the cleaning liquid collected in the tank through an opening formed in the tank, and a circulation system for sucking the cleaning liquid collected in the tank and discharging the cleaning liquid to the object to be cleaned passing through the chamber; A magnetic field applying means for turning on and off the application of a magnetic field to the floor of the chamber; and a nozzle provided on the floor of the chamber and discharging a cleaning liquid toward the opening. Provided.

According to the present invention, a cleaning liquid is discharged to the object to be cleaned passing through the chamber by using a circulating system to be cleaned.
The cleaning liquid used for this cleaning is collected in a tank through an opening formed on the floor of the chamber and is again provided for cleaning.In the coating cleaning apparatus of the present invention, the chamber is cleaned using a magnetic field applying means. Since a magnetic field is applied to the floor, the cleaning liquid discharged to the object to be coated and flowing down is magnetized while reaching the opening along the floor. Therefore, the magnetic foreign matter contained in the cleaning liquid attracts each other while the magnetic field is applied by the magnetic field applying means, and forms a mass having a certain weight. The clumped foreign matter is washed away using a nozzle, collected and settled in a tank, so that even if a lightweight foreign matter is contained, it can be efficiently removed.

The magnetic field applying means according to the present invention is not particularly limited, but according to the third aspect of the present invention, the magnetic field applying means can move toward and away from the outside of the chamber with the floor of the chamber interposed therebetween. It is a magnet body provided. By using a magnet body that moves toward and away from the floor, a member that is easily available and is inexpensive is sufficient.

In the third aspect of the present invention, the magnet body may be manually moved toward and away from the floor, but according to the fourth aspect of the invention, the magnet body is moved toward and away from the floor of the chamber. It is characterized by having a means for making it. This is particularly effective when operating at regular intervals.

Further, as the magnetic field applying means according to the present invention,
The invention according to claim 5 is characterized in that the magnetic field applying means is an electromagnet provided outside the chamber with the floor of the chamber interposed therebetween. By using an electromagnet, ON / OFF of the application of the magnetic field can be executed only by electrically supplying / stopping the current, and there is no need to mechanically operate the magnet body.

The installation position of the magnetic field applying means in the present invention is not particularly limited, but the invention according to claim 6 is characterized in that the magnetic field applying means is provided around an opening in the floor surface. . Since the cleaning liquid discharged in the chamber is collected in the tank from the opening on the floor surface, if the cleaning liquid is installed in the opening, a magnetic field can be applied to all of the cleaning liquid mixed with foreign matter to be removed. .

In the present invention, the use timing of the magnetic field applying means and the nozzle is not particularly limited, but in the invention according to the seventh aspect, the cleaning liquid is discharged from the nozzle while the application of the magnetic field by the magnetic field applying means is stopped. It is characterized by doing. When the application of the magnetic field is cancelled, the clumped foreign matter loses its adsorbing power to the floor surface, so that it can be efficiently collected in the tank by washing it with a nozzle.

[0019] In the present invention, the structure of the tank is not particularly limited.
The cleaning liquid is partitioned into a settling tank section and a spray tank section via a weir, and the cleaning liquid discharged in the chamber is stored in the settling tank section through an opening in the floor surface and stored in the spray tank section. The cleaning liquid thus drawn is suctioned by the circulation system and discharged to the object to be cleaned passing through the chamber. The cleaning liquid containing the clumped foreign matter is put into the settling tank and settled here, thereby preventing the foreign matter from entering the spray tank. As a result, the new cleaning liquid sucked in the circulation system and discharged to the object to be cleaned does not contain foreign matter.

(3) In order to achieve the above object, according to a third aspect of the present invention, a chamber through which an object to be cleaned passes, and a cleaning liquid discharged in the chamber are placed on a floor surface of the chamber. The coating and cleaning apparatus, comprising: a tank that collects the cleaning liquid collected in the tank through an opening formed in the tank; and a circulation system that suctions the cleaning liquid collected in the tank and discharges the cleaning liquid to the object to be cleaned passing through the chamber. A dust separation unit is provided in the system, the dust separation unit includes a liquid inlet, a liquid outlet, and a housing having a concave portion formed so as to face a flow path between these liquid outlets, and an inner surface side of the concave portion of the housing. And a magnetic field applying means for turning on and off the application of a magnetic field.

In the coating and cleaning apparatus according to the second aspect described above, the foreign matter is magnetized in the chamber, but in the present invention, the foreign matter is magnetized in the circulation system. In other words, the cleaning liquid collected in the tank contains foreign matter adhering to the object to be cleaned, but when this is introduced into the liquid inlet of the dust separation means, the magnetic field provided in the recess between the liquid outlet and the liquid outlet. It is magnetized by the application means. As a result, the magnetic foreign matter contained in the cleaning liquid is attracted to each other while the magnetic field is being applied by the magnetic field applying means, and forms a mass having a certain weight. Then, by causing the foreign matter formed into a lump to settle in the housing of the dust separating means, even a lightweight foreign matter can be efficiently removed.

The magnetic field applying means according to the present invention is not particularly limited, but in the invention according to the tenth aspect, the magnetic field applying means is a magnet body provided so as to be able to move in and out of the recess of the housing. It is characterized by the following.
By using a magnet body provided so as to be able to move in and out of the recess, an easily available and inexpensive member is sufficient.

In the tenth aspect of the present invention, the approaching and moving of the magnet body may be performed manually, but in the eleventh aspect of the present invention, the means for moving the magnet body into and out of the recess of the housing is provided. It is characterized by having. This is particularly effective when operating at regular intervals.

Further, as the magnetic field applying means according to the present invention,
According to a twelfth aspect of the present invention, the magnetic field applying means is an electromagnet inserted into a recess of the housing. By using an electromagnet, ON / OFF of the application of the magnetic field can be executed only by electrically supplying / stopping the current, and there is no need to mechanically operate the magnet body.

In the present invention, there is no particular limitation on the timing of removing the foreign matter formed as a lump by magnetization.
In the invention described above, a drain portion is formed in the housing, and the cleaning liquid is discharged from the drain portion in a state where the application of the magnetic field by the magnetic field applying unit is stopped. When the application of the magnetic field is released, the clumped foreign matter loses the adsorbing power, and is efficiently discharged from the drain portion.

In the present invention, the flow path in the housing is not particularly limited, but in the invention according to claim 14, a rectifying plate is provided near at least one of the liquid inlet and the liquid outlet in the housing. It is characterized by having. By providing such a rectifying plate, the cleaning liquid containing foreign matter can be evenly dispersed in the housing, so that the magnetizing efficiency of the magnetic foreign matter by the magnetic field applying means is improved.

[0027]

According to the first, second and ninth aspects of the present invention, even light foreign matters are attracted to each other to form a lump having a certain weight. In addition, foreign substances can be efficiently removed without increasing the capacity of the tank.

According to the third and tenth aspects of the present invention,
Since the magnetic field applying means is constituted by a magnet, an easily available and inexpensive member is sufficient.

According to the fourth and eleventh aspects of the present invention,
It is suitable for automatically removing foreign matter at certain intervals.

According to the fifth and twelfth aspects of the invention,
Since the magnetic field applying means is composed of an electromagnet, ON of the magnetic field application
Since / OFF can be executed electrically, there is no need to mechanically operate the magnet body, which is advantageous in terms of space and durability.

According to the sixth aspect of the present invention, since the magnetic field applying means is provided in the opening, it is possible to apply a magnetic field to all of the cleaning liquid mixed with foreign matter to be removed.

According to the seventh aspect of the present invention, since the lump-shaped foreign matter that has lost the adsorbing power is washed away by the nozzle, it can be efficiently collected in the tank.

According to the eighth aspect of the present invention, the cleaning liquid containing the lump-like foreign matter is put into the settling tank and settled here, so that the foreign matter is prevented from being mixed into the spray tank. It is possible to prevent foreign matter from being mixed into a new cleaning liquid discharged to the object to be cleaned.

According to the thirteenth aspect of the present invention, since the lump-shaped foreign matter having lost the adsorbing power is discharged from the drain portion together with the cleaning liquid, the efficiency of removing the foreign matter is increased.

According to the fourteenth aspect of the present invention, the cleaning liquid containing the foreign matter can be evenly dispersed in the housing, so that the magnetizing efficiency of the magnetic foreign matter by the magnetic field applying means is improved.

[0036]

Embodiments of the present invention will be described below with reference to the drawings. First Embodiment FIG. 1 is a sectional view showing a first embodiment of a coating and cleaning apparatus of the present invention, FIG. 2 is a plan view of the same, and FIG. 3 is a sectional view taken along the line III-III of FIG.

First, an automobile body B to be cleaned is
While being mounted on the coating hanger, it is continuously conveyed at a constant speed by an overhead conveyor. FIG. 1 shows only the body B, and FIG. 2 shows only the installation center of the overhead conveyor C. The body B is transported in a chamber 11 formed in a tunnel shape. In FIG. 2, the sheet is conveyed from left to right.

A plurality of spray pipes 153 are provided on both left and right side walls of the chamber 11, and the washing liquid sucked by the spray pump 151 (water for washing in the washing step,
In the case of a degreasing step, a degreasing liquid is sprayed toward the body B to wash away dust attached to the body B.

As shown in FIGS. 1 to 3, the floor surface 111 of the chamber 11 is inclined downward toward an opening 112 formed substantially at the center. Therefore, when the cleaning liquid sprayed on the body B drips on the floor surface 111, it is guided along the inclined surface to the opening 112, and the opening 112
Falls into the settling tank 12 via the hopper 113 provided on the lower surface of the.

Below the opening 112 in the floor 111, a settling tank 12 and a spray tank 14, which are tanks T according to the present invention, are provided. This tank T
The settling tank 12 and the spray tank 14 are partitioned via a weir 13, and the cleaning liquid overflowing the weir 13 flows into the spray tank 14.

A baffle plate 121 is provided at substantially the center of the settling tank 12 so that the washing liquid dropped from the hopper 113 does not flow toward the weir 13 as it is. The cleaning liquid that has fallen into the settling tank 12 flows through the lower end of the baffle plate 121 as shown by the arrow in FIG. At this time, dust G contained in the cleaning liquid settles in the settling tank 12.

The cleaning liquid flowing into the spray tank 14 is
The liquid is sucked by the spray pump 151 and is injected from the above-described spray pipe 153 to the body B via the pipe 152. The spray pump 151, the pipe 152, and the spray pipe 153 constitute the circulation system 15.

In this embodiment, in particular, the magnet plate (magnet body) 1 is provided below the floor surface 111 (outside the chamber).
61 are provided. As shown in FIG. 2, four magnet plates 161 are provided so as to surround the opening 112 of the floor surface 111.
Reference numeral 1 denotes a floor surface 1 around each rotation shaft 161a.
It is provided rotatably at a position approaching 11 and a position away from it. In this case, in order to separate the magnet plate 161 from the floor surface 111, it is necessary that the magnetic portion (shaded portion) of the magnet plate 161 is slightly offset from the rotation shaft 161a.

The movement of the magnet plate 161 toward and away from the cylinder can be automated by the vertical movement of the rod of the cylinder 162. That is, as shown in FIG. 4, the rod of the cylinder 162 is pressed against the tip of the magnet plate 161 via the rotating shaft 162a, and when the rod is pushed up, as shown in FIG. The magnet plate 161 is separated from the floor surface 111 by approaching the surface 111 and lowering the rod as shown in FIG. Incidentally, at least a portion of the floor surface 111 facing the magnet plate 161 is formed of a non-magnetic material.

In the present embodiment, nozzles 17 are provided on four sides of the floor surface 111 as shown in FIG. 2, and the cleaning liquid is used to wash away the dust G adsorbed by the magnetic field of the magnet plate 161. The direction of each discharge port is set so as to flow along the floor surface 111 and toward the opening 112. The supply of the cleaning liquid to the nozzle 17 can be performed, for example, by using a circulation system 15 provided in the spray tank 14.
However, as will be described later, since the discharge of the cleaning liquid from the nozzle 17 is related to the operation of the magnet plate 161, it is desirable to provide an electromagnetic on-off valve or the like upstream of the nozzle 17.

Next, the operation will be described. FIG. 4 is a cross-sectional view for explaining the foreign matter removing method of the present embodiment, and FIG. 5 is a graph showing the relationship between the particle size of dust brought into the coating line and the sedimentation speed of the dust.

When the present inventors examined the relationship between the particle size of dust brought into the coating line and the sedimentation speed of the dust, the results shown in FIG. 5 were obtained. As shown in the figure, the dust brought into the coating line ranges from small and light particles having a particle size of 100 μm or less to large and heavy particles having a particle size of 600 μm or more. Above all, the sedimentation speed of lightweight dust of 100 μm or less is about 2 cm / sec. on the other hand,
The flow rate of the cleaning liquid from the settling tank 12 to the spray tank 14, that is, the flow rate in the tank T is 10
About cm / sec is required. Therefore, for example, if the capacity of the circulation system 15 is set so that the flow velocity in the tank T becomes 10 cm / sec, small and light dust having a particle size of 200 μm or less will flow immediately after settling. Cannot be removed by sedimentation. In other words, such lightweight dust flows into the spray tank 14 over the weir 13 and is again injected into the body B.

However, in the coating and cleaning apparatus 1 of this embodiment, first, as shown in FIG.
The cleaning liquid is sprayed onto the body B in a state where the cleaning unit 61 is brought close to the floor surface 111 of the chamber 11. As a result, dust adhering to the body B is washed away with the cleaning liquid, falls on the floor 111, and flows toward the opening 112. At this time, since a magnetic field is applied to the floor 111 by the magnet plate 161, In addition, magnetic dust such as iron powder (for example, welding spatter) contained in the cleaning liquid is magnetized by the magnet plate 161,
Adsorb each other. Due to such an action, even the light dust is turned into some lump dust G as shown in FIG.

Next, when the body B is interrupted,
The magnet plate 161 is separated from the floor surface 111 by lowering the rod of the cylinder 162 as shown in FIG. At the same time, the cleaning liquid is sprayed from the nozzle 17 to release the floor surface 11.
Wash off 1 When the magnet plate 161 is separated from the floor surface, the lump of dust G which has been adsorbed to the floor surface is released from the floor surface 111 and is washed away toward the opening 112 with the cleaning liquid from the nozzle 17. The dust particles G fall into the settling tank 12 while sucking each other, that is, in a lump state.

[0050] Then, even if light dust having a size of 100 µm or less is washed out from the body B, since it is gathered, it will have a weight of at least 200 µm or more. As a result, the sedimentation speed is higher than the flow velocity in the tank T, so that the sedimentation is appropriately performed in the settling tank 12. That is, it is possible to prevent the water from flowing into the spray tank 14 beyond the weir 13.

Incidentally, the refuse G settled in the settling tank 12 is discarded, for example, at the time of periodic cleaning of the coating line.

Second Embodiment FIG. 6 is a sectional view showing a second embodiment of the coating and cleaning apparatus of the present invention, and FIG. 7 is a sectional view showing a dust separating apparatus according to the second embodiment.

This embodiment is different from the first embodiment in that a dust separator 18 is provided in the circulation system 15 in place of the magnet plate 161 and the nozzle 17 of the first embodiment. The tank T is a single tank without being divided into a settling tank and a spray tank. Other configurations are the same as those of the first embodiment, and corresponding members are denoted by the same reference numerals.

The dust separating apparatus 18 according to this embodiment has a housing 181 in which a liquid inlet 182, a liquid outlet 183, and a drain portion 184 are formed as shown in FIG. 7, and a spray pump 151 shown in FIG. The washing liquid in the tank T sucked in is supplied to the liquid inlet 182 and the liquid outlet 183.
The cleaning liquid from the spray pipe 153 is supplied through the pipe 152.
It is led to.

A part of the housing 181 is
5 and a magnet rod 186 is provided in the recess 185.
Are provided so that they can appear and disappear. The movement of the magnet bar 186 may be performed by means such as a cylinder, or may be performed manually. By the way, at least the housing 181
Is formed of a non-magnetic material.

In the housing 181, a current plate 187,
187 is provided, whereby the cleaning liquid flowing from the liquid inlet 182 spreads over the entire housing, and the recess 18 is provided.
Foreign matter will be dispersed around 5.

Reference numeral "184V" denotes an electromagnetic valve provided in the drain portion 184, and is opened when dust collected in the housing 181 is discarded outside the system.

Next, the operation will be described. First, as shown in FIG. 7, with the magnet bar 186 inserted into the concave portion 185,
The cleaning liquid is sucked from the tank T by the spray pump 151, and the cleaning liquid is jetted to the body B by the circulation system 15.
As a result, dust adhering to the body B is washed away by the cleaning liquid and falls on the floor surface 111 of the chamber 11, and the opening 11
2 to tank T. Therefore, various kinds of dust are mixed in the cleaning liquid in the tank T.

When the cleaning liquid in the tank T is sucked by the spray pump 151 and introduced into the liquid inlet 182 of the dust separator 18, the cleaning liquid spreads over the entire inside of the housing 181 by the rectifying plate 187, and the periphery of the concave portion 185 is formed. pass. At this time, since a magnetic field is applied to the concave portion 185 by the magnet bar 186, magnetic dust such as iron powder (for example, welding spatter) contained in the cleaning liquid is magnetized by the magnet bar 186 and is attracted to each other. Due to such an action, even light dust is turned into a certain amount of lump dust G as shown in FIG.

Next, when the body B is interrupted,
The magnet bar 186 is pulled out from the concave portion 185. At the same time, the valve 184V of the drain 184 is opened. When the magnet rod 186 is pulled out of the concave portion 185, the lump G of dust that has been adsorbed around the concave portion 185 is released from the concave portion 185, falls by its own weight toward the drain portion 184, and goes out of the system together with the cleaning liquid. Discarded.

The embodiments described above are described for facilitating the understanding of the present invention, but are not described for limiting the present invention. Therefore, each element disclosed in the above embodiment is intended to include all design changes and equivalents belonging to the technical scope of the present invention.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a first embodiment of a coating and cleaning apparatus of the present invention.

FIG. 2 is a plan view showing the first embodiment.

FIG. 3 is a sectional view taken along the line III-III of FIG. 2;

FIG. 4 is a cross-sectional view for explaining a foreign matter removing method according to the first embodiment.

FIG. 5 is a graph showing the relationship between the particle size of dust brought into a coating line and the sedimentation speed of dust.

FIG. 6 is a sectional view showing a second embodiment of the coating and cleaning apparatus of the present invention.

FIG. 7 is a cross-sectional view illustrating a dust separation device according to a second embodiment.

FIG. 8 is a sectional view showing a conventional coating and cleaning apparatus.

DESCRIPTION OF SYMBOLS 1 ... Coating and washing apparatus 11 ... Chamber 111 ... Floor surface 112 ... Opening T ... Tank 12 ... Set ring tank 13 ... Weir 14 ... Spray tank 15 ... Circulation system 16 ... Magnetic field applying means 161 ... Magnet plate 162 ... Cylinder 17 ... Nozzle 18 ... Dust separation device (dust separation means) 181 ... Housing 182 ... Liquid inlet 183 ... Liquid outlet 184 ... Drain part 185 ... Recess 186 ... Magnet rod 187 ... Rectifying plate

Claims (14)

[Claims] 1. A method according to claim 1, wherein a magnetic field is applied to the cleaning liquid sprayed onto the object to be cleaned for a predetermined time to magnetize magnetic foreign substances contained in the cleaning liquid, and then the magnetized foreign substances are aggregated and settled. To remove light foreign matter. 2. A chamber through which an object to be cleaned passes, a tank for collecting the cleaning liquid discharged in the chamber through an opening formed in the floor of the chamber, and a cleaning liquid collected in the tank. A coating and cleaning apparatus, comprising: a circulating system that sucks and discharges the object to be cleaned passing through the chamber; and a magnetic field application unit that switches on and off the application of a magnetic field to a floor surface of the chamber; A nozzle provided on the surface and discharging a cleaning liquid toward the opening. 3. The coating and cleaning apparatus according to claim 2, wherein said magnetic field applying means is a magnet body provided so as to be able to move toward and away from the outside of said chamber with a floor surface of said chamber interposed therebetween. 4. The coating and cleaning apparatus according to claim 3, further comprising means for moving the magnet body toward and away from the floor of the chamber. 5. The coating and cleaning apparatus according to claim 2, wherein said magnetic field applying means is an electromagnet provided outside said chamber with a floor of said chamber interposed therebetween. 6. The coating and cleaning apparatus according to claim 2, wherein said magnetic field applying means is provided around an opening in said floor surface. 7. The coating and cleaning apparatus according to claim 2, wherein the cleaning liquid is discharged from the nozzle while the application of the magnetic field by the magnetic field applying unit is stopped. 8. The tank is divided into a settling tank section and a spray tank section through a weir, and the cleaning liquid discharged in the chamber is supplied to the settling tank section through an opening in the floor surface. The coating liquid according to any one of claims 2 to 7, wherein the cleaning liquid stored and stored in the spray tank portion is sucked by the circulation system and discharged to an object to be cleaned passing through the chamber. Cleaning equipment. 9. A chamber through which an object to be cleaned passes, a tank for collecting the cleaning liquid discharged in the chamber through an opening formed in the floor of the chamber, and a cleaning liquid collected in the tank. A paint cleaning apparatus comprising: a circulating system that suctions and discharges the object to be cleaned passing through the chamber; wherein the circulating system is provided with dust separating means; A coating comprising: a housing having a recess formed so as to face a flow path between the liquid inlet and outlet; and a magnetic field applying means for turning on and off the application of a magnetic field to an inner surface side of the recess of the housing. Cleaning equipment. 10. The coating and cleaning apparatus according to claim 9, wherein said magnetic field applying means is a magnet body provided so as to be able to move in and out of a recess of said housing. 11. A coating and cleaning apparatus according to claim 10, further comprising means for moving said magnet body into and out of said recess of said housing. 12. The apparatus according to claim 9, wherein said magnetic field applying means is an electromagnet inserted into a recess of said housing. 13. A drain portion is formed in the housing,
In a state where the application of the magnetic field by the magnetic field applying unit is stopped,
The coating and cleaning apparatus according to any one of claims 9 to 12, wherein the cleaning liquid is discharged from the drain part. 14. The coating and cleaning apparatus according to claim 9, wherein a current plate is provided near at least one of the liquid inlet and the liquid outlet in the housing.