JP2019127642A - Electrodeposition coating method and device - Google Patents

Abstract

To suppress unevenness of an electrodeposition coating layer formed on a surface of a coated matter on which an amorphous thin film chemical conversion treatment layer is formed.SOLUTION: The electrodeposition coating method comprises: a chemical conversion treatment step for forming a chemical conversion treatment layer on a surface of an automotive body; and an electrodeposition coating step for forming an electrodeposition coating layer on the chemical conversion treatment layer. The chemical conversion treatment step includes a chemical conversion step for forming an amorphous thin film chemical conversion treatment layer on a surface of the automotive body, the electrodeposition coating step includes a first electrodeposition step for forming a first electrodeposition coating on the automotive body, a thermal flow step for performing thermal flow of the first electrodeposition coating so that, electric resistance of the first electrodeposition coating formed on an external plate part of the automotive body becomes higher than that of the first electrodeposition coating formed on an inner plate part, and a second electrodeposition step for forming a second electrodeposition coating on the automotive body.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an electrodeposition coating method and an electrodeposition coating apparatus.

  A metal member represented by an automobile body or the like may be subjected to electrodeposition coating, but before applying this electrodeposition coating, the metal member is degreased and cleaned, and then a chemical conversion film (chemical conversion treatment layer) is formed. Processing is performed.

  In conventional electrodeposition coating pretreatment, a degreasing and cleaning step of removing oil, iron powder, dust, etc. adhering to the metal member, and a chemical conversion treatment of forming a zinc phosphate-based conversion film on the surface of the cleaned metal member Process. This zinc phosphate chemical conversion treatment can deposit a film excellent in corrosion resistance on the surface of a steel such as a hot rolled steel plate or a cold rolled steel plate, a galvanized steel plate, and a part of aluminum alloy.

  However, since the zinc phosphate chemical conversion treatment forms a chemical conversion film by a chemical reaction, conversion sludge containing phosphorus, which causes eutrophication, is inevitably generated in lakes and lakes, etc., resulting in a large environmental load. There was a problem.

  Therefore, for example, as shown in Patent Document 1, using a chemical conversion treatment solution containing at least one member selected from the group consisting of zirconium, titanium and hafnium and fluorine and containing substantially no phosphate ion for chemical conversion treatment Therefore, the generation of sludge can be suppressed and the load on the environment can be reduced.

JP 2004-218073 A

  By the way, the chemical conversion film formed by the zirconium-based chemical conversion treatment solution as described in Patent Document 1 is a non-crystalline film, and has a thinner film thickness than the chemical conversion film formed by the phosphoric acid-based chemical conversion treatment solution. As a result, the throwing power of the electrodeposition coating (the ability to form a coating film to every corner of the object to be coated and the ability of the coating film to have a uniform thickness) is reduced, and it is formed on a thin film conversion coating. Unevenness is likely to occur in the electrodeposition coating layer.

  This invention is made in view of such a point, The place made into the objective is the nonuniformity of the electrodeposition coating film layer which arises on the surface of the to-be-coated-article in which the chemical conversion treatment layer of the amorphous thin film was formed. It is to suppress.

  In order to achieve the above object, in the first invention, a chemical conversion treatment step for forming a chemical conversion treatment layer on the surface of the article to be coated, and a surface of the article to be coated on which the chemical conversion treatment layer is formed after the chemical conversion treatment step An electrodeposition coating step of forming an electrodeposition coating layer on the surface of the object to be coated by immersing the object in a chemical conversion solution. In the first electrodeposition tank, a direct current voltage is applied between the substrate on which the chemical conversion treatment layer is formed and a counter electrode. A first electrodeposition step of forming a first electrodeposition coating film on the coating object, and a portion close to the counter electrode of the coating object on which the first electrodeposition coating film is formed after the first electrodeposition step. The electrical resistance of the formed first electrodeposition coating film is higher than the electrical resistance of the first electrodeposition coating film formed at a portion far from the counter electrode. In the heat flow step of performing the heat flow of the first electrodeposition coating film, and the coated object and the counter electrode in which the heat flow is applied to the first electrodeposition coating film in the second electrodeposition tank after the heat flow step. A second electrodeposition step of forming a second electrodeposition coating on the substrate by applying a DC voltage between the first electrodeposition coating and the second electrodeposition after the second electrodeposition step. And curing the coating film by heating.

  According to the said structure, in a 1st electrodeposition tank, a 1st voltage is applied to the surface of a to-be-coated object by applying a DC voltage between the to-be-coated object in which the amorphous thin film chemical conversion treatment layer was formed, and a counter electrode. An electrodeposition coating is formed. The first electrodeposition coating is formed thick at a portion where the current density is high near the counter electrode, and thin at a portion where the current density is low from the counter electrode.

  Subsequently, the electrical resistance of the first electrodeposition coating formed on the portion near the counter electrode of the substrate on which the first electrodeposition coating is formed is the same as that of the first electrodeposition coating formed on the portion far from the counter electrode By performing the heat flow of the first electrodeposition coating film so as to be higher than the electric resistance, in the subsequent second electrodeposition step, the counter electrode is compared with the first electrodeposition coating film formed at a position close to the counter electrode. A second electrodeposition film is thickly formed on the first electrodeposition film formed at a portion far from the surface.

  And a 2nd electrodeposition coating film is formed in a to-be-coated article by applying a direct current voltage between the to-be-coated object in which the heat flow was given to the 1st electrodeposition coating film, and a counter electrode. . As a result, it is easy to control the thickness of the electrodeposition coating film that combines the first electrodeposition coating film and the second electrodeposition coating film at a portion near the counter electrode and a portion far from the counter electrode to a desired thickness. become.

  Therefore, since the thickness of the electrodeposition coating film of each of the part near the counter electrode of the coated article and the part far from the counter electrode can be easily controlled to a desired thickness, the coated film on which the amorphous thin film conversion treatment layer is formed It is possible to suppress unevenness of the electrodeposited coating layer generated on the surface of an object.

  In a second invention, in the first invention, the electrodeposition coating step includes the first electrodeposition coating film after the first electrodeposition step, after the first electrodeposition step and before the heat flow step. And the washing step for washing the substrate on which the water has been formed, and the washing step for removing or reducing the washing water on the substantially horizontal washing water stagnant surface of the article, in which the washing water for washing is stagnated after the washing step. And a water removal reducing step.

  According to the said structure, after a 1st electrodeposition process and before a heat flow process, the 1st electrodeposition coating material is included by including the water-washing process of washing the to-be-coated article in which the 1st electrodeposition coating film was formed. Taking out of the first electrodeposition step can be minimized.

  Here, after the water-washing step of washing the substrate on which the first electrodeposition coating has been formed, the heat flow step is performed on the first electrodeposition coating while a portion of the washing water for washing is left. In the first electrodeposition film, a recess is formed at the boundary between the portion wet with the cleaning water and the dry portion to which the cleaning water is not attached. When the second electrodeposition coating is performed in a state where such a concave portion is formed, the electrodeposition paint is liable to adhere because the electric resistance of the portion which is the concave portion is lower than the surrounding area. For this reason, the second electrodeposition coating film in a portion corresponding to the boundary between the wet portion and the dry portion is locally thickened to form a convex portion. In this case, even if the middle coat coating and the top coat coating are performed on the electrodeposition coating which is the undercoat, the smoothness is not obtained on the coated surface, or the unevenness of the electrodeposition coating which is the undercoat is middle. Appearance appears through the coated film and the overcoated film, and the appearance becomes worse.

  According to the above configuration, the washing water on the stagnation surface of the washing water that is substantially horizontal of the article to be coated in which the washing water for washing stagnates after washing the article on which the first electrodeposition coating film is formed. By removing or reducing the above, it is possible to suppress the formation of recesses on the surface of the first electrodeposition coating film in the subsequent heat flow step. Further, even if the wash water on the wash water stagnation surface is not completely removed and remains partially, the remaining amount of the wash water is small, so in the subsequent heat flow step, heating for the heat flow is performed. Causes the wash water to evaporate quickly. That is, since the volume contraction difference between the wet portion and the dry portion of the first electrodeposition coating does not last long during the heat flow, the boundary between the wet portion and the dry portion It is avoided to produce a recess in the Even if the concave portion is generated, the concave portion is shallow, so that even if the second electrodeposition coating film is formed after the heat flow, it is possible to suppress the generation of a large uneven portion on the second electrodeposition coating film. Therefore, since it can suppress that a recessed part arises on the surface of a 1st electrodeposition coating film, the nonuniformity of an electrodeposition coating film layer can be suppressed further.

  In a third invention, in the second invention, the washing water removing and reducing step is a step of spraying a gas on the washing water stagnant surface such that the washing water is removed from the washing water stagnant surface. Do.

  According to said structure, since the washing water of a washing water stagnation surface can be removed or reduced by spraying the gas to the washing water stagnation surface of a to-be-coated object, the nonuniformity of an electrodeposition coating layer is further suppressed. can do.

  In a fourth invention, in the second or third invention, the water washing step is a dip water washing step in which the object on which the first electrodeposition coating film is formed is immersed in washing water stored in a dip water washing tank. And before or after the dip rinsing step, and a spray rinsing step of spraying rinsing water on the article on which the first electrodeposition coating film is formed.

  According to the above configuration, the object on which the first electrodeposition coating film is formed is sufficiently washed by the dip water washing step and the spray water washing step, so that the effect of the next washing water removal and reduction step is enhanced. Unevenness of the film layer can be further suppressed.

  In a fifth invention, in any one of the first to fourth inventions, the heat flow in the heat flow step is to apply hot air having a temperature lower than the baking temperature of the first electrodeposition coating film. It is performed by spraying on an object.

  According to said structure, since the heat flow of a heat flow process sprays the warm air of temperature lower than the baking temperature of a 1st electrodeposition coating film on a to-be-coated article, it is not heating by radiation but heating by warm air. Therefore, even if washing water remains on the surface of the first electrodeposition coating, the washing water is rapidly removed. Therefore, it can suppress that a recessed part arises on the surface of a 1st electrodeposition coating film, and can suppress the nonuniformity of an electrodeposition coating film layer further.

  According to a sixth aspect, in the fifth aspect, the heat flow of the heat flow step is such that the first electrodeposition coating film formed at a position close to the counter electrode of the article to be coated in the first electrodeposition tank is 70. C. to 100.degree. C. for several minutes.

  By the way, when the heating temperature of the heat flow is low, or when the heating time is short, the heat flow of the first electrodeposition coating film in the portion close to the counter electrode of the object to be coated becomes insufficient, and the electric resistance is sufficient. Therefore, it is disadvantageous in forming a second electrodeposition coating film having a desired thickness in a portion far from the counter electrode of the object to be coated. On the other hand, when the heating temperature is high, or when the heating time is long, the first electrodeposition coating film that is thinly formed at a site far from the counter electrode of the object to be coated flows into a dense coating film, that is, The electrical resistance becomes high, which is disadvantageous for the formation of the second electrodeposition coating film on this far site.

  According to said structure, the heat flow of a heat flow process is as follows. The 1st electrodeposition coating film formed in the site | part close | similar to the counter electrode of the to-be-coated object in a 1st electrodeposition tank is heated for several minutes from 70 degreeC to 100 degreeC. Therefore, the second electrodeposition coating film having a desired thickness can be formed. Therefore, the nonuniformity of an electrodeposition coating film layer can be suppressed further.

  According to a seventh invention, in any one of the first to sixth inventions, the chemical conversion solution used in the chemical conversion step is a zirconium oxide treatment liquid.

  According to the above configuration, since the zirconium oxide treatment liquid is used in the chemical conversion treatment step, the chemical conversion treatment has a low environmental impact while suppressing unevenness of the electrodeposition coating layer on the amorphous thin film chemical conversion treatment layer. Can be applied to the workpiece.

  In an eighth invention according to any one of the first to seventh inventions, the method further comprises a degreasing and washing step of removing dirt or oil on the surface of the substrate before the chemical conversion treatment step, In the cleaning step, a degreasing tank storing degreasing solution is provided in advance, and an object to be coated before removing dirt or oil on the surface is immersed in the degreasing solution, and an ultrasonic transducer disposed at the lower part of the degreasing tank And degreasing and cleaning the substrate by ultrasonic vibration of the degreasing solution.

  By the way, since a chemical conversion treatment layer is a thin film, the washing | cleaning state of the to-be-coated article in the degreasing washing process which is a pre-process of a chemical conversion treatment process influences notably the formation of a chemical conversion treatment layer. That is, when a large amount of oil, iron powder, or the like remains on the object to be coated, it is difficult to form a thin chemical conversion coating layer, and unevenness of the electrodeposition coating layer is likely to occur.

  According to the above configuration, the object to be coated is degreased and cleaned by ultrasonically vibrating the degreasing solution with the ultrasonic vibrator disposed at the lower part of the degreasing tank. Therefore, compared with cleaning using water pressure by spraying, for example, A portion which is not exposed to the outside such as the inside of the bag-like portion of the coating can be sufficiently degreased and washed. By this, the nonuniformity of an electrodeposition coating film layer can be further suppressed in the electrodeposition coating process of a post process.

  A ninth invention is characterized in that, in any one of the second to eighth inventions, the article to be coated is an automobile body, and the washing water stagnation surface is a roof of the automobile body.

  By the way, for example, in the case of an automobile body, not only the outer plate part exposed to the outside but also the inner plate part not exposed to the outside such as the interior of the vehicle interior, the engine room, the inside of the bag-shaped part, etc. When an electrodeposition coating film having a predetermined thickness is desired to be formed, the throwing power of the electrodeposition coating film tends to be reduced in the automobile body having the complicated structure as described above.

  Here, according to the above configuration, since the object to be coated is an automobile body and the washing water stagnant surface is a roof of the automobile body, it is possible to suppress unevenness of the electrodeposited coating layer of the automobile body, In particular, even in the roof of an automobile body where cleaning water tends to remain, unevenness of the electrodeposited coating layer can be suppressed.

  In the tenth invention, a chemical conversion treatment means for forming a chemical conversion treatment layer on the surface of an object to be coated, and an electrodeposition coating means for forming an electrodeposition coating layer on the surface of the object to be coated on which the chemical conversion treatment layer is formed. The chemical conversion treatment means has a chemical conversion tank in which a chemical conversion solution is stored, and an object to be coated is immersed in the chemical conversion solution to form an amorphous on the surface of the object to be coated. A chemical conversion means for forming a thin chemical conversion treatment layer is provided, the electrodeposition coating means has a first electrodeposition tank, and a DC voltage is applied between an object to be coated on which the chemical conversion treatment layer is formed and a counter electrode. The first electrodeposition means for forming the first electrodeposition coating film on the object to be coated, and the first electrode formed at a position near the counter electrode of the object on which the first electrodeposition film is formed. Heat flow of the first electrodeposition coating film so that the electric resistance of the coating film is higher than the electric resistance of the first electrodeposition coating film formed at a site far from the counter electrode. A heat flow means to perform, a second electrodeposition tank, and a DC voltage is applied between the object to be coated and the counter electrode having a heat flow applied to the first electrodeposition coating film. (2) A second electrodeposition means for forming an electrodeposition coating film, and a curing means for heating and curing the first electrodeposition coating film and the second electrodeposition coating film.

  According to said structure, the effect similar to 1st invention can be acquired.

  In an eleventh invention according to the tenth invention, the electrodeposition coating means is an article to be coated in which the first electrodeposition coating film is formed between the first electrodeposition means and the heat flow means. Washing means for washing the washing water, and washing water removal reducing means for removing or reducing washing water on the washing water stagnation surface, which is substantially horizontal of the object to be coated, in which washing water for washing in the washing means stagnates. It is characterized by having.

  According to the above configuration, the same function and effect as those of the second invention can be obtained.

  In a twelfth invention, in the eleventh invention, the cleaning water removal and reduction means includes a blow nozzle for blowing a gas on the cleaning water stagnant surface so that the cleaning water is removed from the cleaning water stagnant surface. I assume.

  According to the above configuration, the same effect as that of the third invention can be obtained.

  In a thirteenth invention, in the eleventh or the twelfth invention, the water washing means includes a dip water washing tank storing washing water for immersing a substrate on which the first electrodeposition coating film is formed, and the dip water washing Before or after the bath, the apparatus is characterized by comprising a spray nozzle for spraying washing water to the substrate on which the first electrodeposited film is formed.

  According to the above configuration, the same function and effect as those of the fourth invention can be obtained.

  In a fourteenth aspect of the invention, in any one of the tenth to thirteenth aspects of the invention, the heat flow means is applied to the article to be coated from which the washing water has been removed or reduced from the baking temperature of the first electrodeposition coating film. It is characterized by comprising a thermal flow device for blowing warm air of low temperature.

  According to the above configuration, the same function and effect as those of the fifth invention can be obtained.

  According to a fifteenth aspect, in any one of the tenth to fourteenth aspects, the chemical conversion tank stores a zirconium oxide treatment liquid as the chemical conversion solution.

  According to the above configuration, the same function and effect as those of the seventh invention can be obtained.

  In a sixteenth aspect of the invention, in any one of the tenth to fifteenth aspects of the invention, the degreasing step further includes degreasing and cleaning means for removing dirt or oil on the surface of the article to be coated before the chemical conversion treatment means. The cleaning means has a degreasing tank in which the degreasing solution is stored, and the object to be coated before removing the dirt or oil on the surface is immersed in the degreasing solution, and the ultrasonic vibration disposed in the lower part of the degreasing tank The apparatus is characterized by comprising a degreasing means for degreasing and cleaning the object by ultrasonically vibrating the degreasing solution with a needle.

  According to the above configuration, the same function and effect as those of the eighth invention can be obtained.

  In the seventeenth invention, the twelfth invention, the thirteenth invention in the twelfth invention, the fourteenth invention in the twelfth invention, the fifteenth invention in the twelfth invention, or the twelfth invention In any one of the sixteenth inventions of the present invention, the object to be coated is an automobile body, the washing water stagnant surface is a roof of the automobile body, and the heat flow means extends from the water wash means to the heat flow means. The vehicle further comprises a guide rail extending and a hanger suspended on the guide rail, mounted on the car body and transported from the water washing means to the heat flow means, and the blow nozzle is used to cover the roof of the car body. The automobile body is mounted on the hanger and disposed above the hanger with the gas outlet facing downward so as to be blown to the blow nozzle. A solenoid valve for controlling supply and stop of gas, gas is supplied to the blow nozzle while the roof of the car body passes in front of the gas outlet of the blow nozzle, and a frame forming the hanger is A control device for controlling the operation of the solenoid valve in accordance with the transport position of the vehicle body so that the supply of the gas is stopped when crossing the front of the gas outlet of the blow nozzle; Do.

  According to the above configuration, the washing water on the roof which is the washing water stagnant surface is removed or reduced by the blowing of the gas while being transported from the water washing means to the heat flow means with the car body mounted on the hanger it can. When the frame constituting the hanger crosses the front of the gas outlet of the blow nozzle, the supply of the gas is stopped, so foreign substances such as dust and oil that may be attached to the frame are blown away by the gas and covered Adherence to paint is avoided. Therefore, the nonuniformity of an electrodeposition coating film layer can be suppressed further.

  Only one blow nozzle may be disposed above the hanger, or a plurality of blow nozzles may be disposed above the hanger.

  As mentioned above, according to this invention, the nonuniformity of the electrodeposition coating film layer which arises on the surface of the to-be-coated-article in which the non-crystalline thin film chemical conversion treatment layer was formed can be suppressed.

It is a figure which shows the flow of the process using the electrodeposition coating method which concerns on embodiment of this invention. It is sectional drawing which shows typically the degreasing tank provided in the degreasing washing | cleaning area of an electrodeposition coating line. It is a figure which shows the electrodeposition coating area of an electrodeposition coating line. It is sectional drawing which shows typically the 1st electrodeposition tank provided in the electrodeposition coating area of the electrodeposition coating line. It is the front view made into a partial cross section which shows the cleaning water removal promotion apparatus (air blow apparatus) provided in the electrodeposition coating area of the electrodeposition coating line. It is a side view of the same device. It is a top view of the same device. It is a cross-sectional view of the coating-film heat flow apparatus provided in the electrodeposition coating area of the electrodeposition coating line. It is a longitudinal cross-sectional view of the same device.

  Hereinafter, an embodiment for carrying out the present invention will be described based on the drawings. The following description of the preferred embodiments is merely exemplary in nature and is not intended to limit the invention, its applications or its uses.

<Overall configuration>
FIG. 1 is a diagram showing the flow of steps using the electrodeposition coating method according to the present embodiment. The object to be electrodeposited by the electrodeposition coating apparatus E is an automobile body 1 (see FIG. 2 and the like). The electrodeposition coating apparatus E includes an electrodeposition coating line L. The electrodeposition coating line L includes a degreasing cleaning area A, a chemical conversion treatment area B, and an electrodeposition coating area C in order from the upstream side. The automobile body 1 is transported by a hanger type transportation device described later. Specifically, the automobile body 1 is mounted on a hanger 45 (see FIGS. 6, 8, and 9) and is sent in the order of the areas A, B, and C.

<Degreasing and cleaning area A>
The degreasing and cleaning area A is an area for removing dirt or oil and fat from the surface of the automobile body 1. In the degreasing and cleaning area A, a first water washing station A1, a degreasing and cleaning station A2, and a second water washing station A3 are arranged in this order from the upstream side of the electrodeposition coating line L. At the first water washing station A1, the car body 1 is washed with water before removing dirt or oil on the surface. Therefore, the 1st water washing station A1 is provided with the dip water washing tank or the spray nozzle (spray water washing apparatus). The automobile body 1 is cleaned by immersing it in cleaning water stored in a dip rinsing tank or by spraying cleaning water using a spray nozzle. The temperature of the washing water discharged from the dip washing tank or from the spray nozzle is 40 ° C to 50 ° C. As described above, the oil and fat adhering to the surface of the automobile body 1 can be easily removed by washing with water at a temperature higher than room temperature.

  As shown in FIG. 2, the degreasing tank A13 is provided with a degreasing solution A12 for storing the degreasing solution A12 in which the automobile body 1 washed in the first water washing station A1 is immersed. A plurality of ultrasonic transducers A14 are disposed below the degreasing tank A13. The degreasing solution A12 vibrates by the ultrasonic vibration of the ultrasonic vibrator A14. At this time, innumerable small air bubbles are generated in the degreasing solution A12, and the generated air bubbles collide with the automobile body 1 and burst. Degreasing and cleaning is performed by removing dirt and fats and oils adhering to the surface of the automobile body 1 by shock waves generated at this time. The temperature of the degreasing solution A12 in the degreasing tank A13 is 40 ° C to 50 ° C. The degreasing cleaning process by the ultrasonic vibrator A14 is performed for about 1 to 2 minutes. As a result, the dirt or grease of 90% or more of the area of the entire automobile body 1 is cleaned. In the present embodiment, the degreasing tank A13 and the ultrasonic vibrator A14 disposed below the degreasing tank A13 correspond to the degreasing means of the present invention.

  As the degreasing solution A12, the filtrate obtained by the filtration device A15 of the degreasing tank A13 is used. Therefore, filtration apparatus A15, pump A16, and spray nozzle A17 are connected to degreasing tank A13 in order from the upstream side, and spray nozzle A17 is provided in degreasing tank A13. In the filtration device A15, the defatted solution A12 is centrifuged and then passed through a filter to remove oil components, iron powder and the like in the solution. That is, in order to reduce waste of the degreasing solution A12, the degreasing solution A12 used in the degreasing washing passes through the filtering device A15 to remove oil and iron powder and the like, and the filtrate from which the oil etc. is removed is sprayed by the pump A16. It is supplied to the degreasing tank A13 through the nozzle A17.

  On the downstream side of the degreasing tank A13, an inclined part A18 for further removing oil and fat, iron powder and the like remaining in the automobile body 1 degreased and washed in the degreasing tank A13 is provided. The inclined portion A18 is inclined upward from the upstream side toward the downstream side. Spray nozzles A19 are arranged on both sides of the automobile body 1 in the inclined portion A18. The degreasing solution A12 is supplied from the spray nozzle A19 and sprayed onto the vehicle body 1. The car body 1 is immersed in the degreasing solution together with the hanger 45, but the transport device is omitted in FIG.

  In the second water washing station A3, dip water washing, spray water washing, dip water washing, and spray water washing are sequentially performed on the automobile body 1 degreased and cleaned in the degreasing and washing station A2, similarly to the fifth water washing station 7 described later. For that purpose, a first dip washing tank, a first spray nozzle, a second dip washing tank, and a second spray nozzle are provided.

<Chemical conversion treatment area B>
The chemical conversion treatment area B is an area for forming a chemical conversion treatment layer on the surface of the automobile body 1 from which the dirt or oil and fat has been removed. In the chemical conversion treatment area B, a chemical conversion treatment station B1 and a third water washing station B2 are arranged in order from the upstream side of the electrodeposition coating line. The chemical conversion treatment station B1 is provided with a chemical conversion tank (chemical conversion means) that stores a chemical conversion solution in which the automobile body 1 from which dirt or oil and fat have been removed by degreasing cleaning is immersed. In the chemical conversion tank, a zirconium oxide treatment liquid for forming an amorphous thin film as a chemical conversion solution is stored. The temperature of the conversion solution is about 40 ° C. The processing time from immersing the automobile body 1 in the chemical conversion tank to forming the chemical conversion treatment layer is about 2 to 3 minutes. A chemical conversion treatment layer of about 0.02 μm is formed on the surface of the automobile body 1 by this chemical conversion treatment.

  A filtration device, a pump, and a spray nozzle are connected to the chemical conversion tank in order from the upstream side, and the spray nozzle is provided in the chemical conversion tank. In the filtration device, sedimentation by gravity or the formation solution is centrifuged and then passed through a filter to remove formation sludge in the solution. In other words, in order to efficiently use the chemical conversion solution, the chemical conversion solution used in the chemical conversion treatment passes through a filtration device, the chemical conversion sludge is removed, and the filtrate from which chemical conversion sludge has been removed is converted by a pump through a spray nozzle. It is supplied to the tank.

  In the third water washing station B2, dip water washing and subsequent spray water washing of the automobile body 1 on which the chemical conversion treatment layer is formed are performed. For that purpose, a dip washing tank and a spray nozzle are provided. The automobile body 1 is cleaned by being immersed in the cleaning water stored in the dip rinsing tank, and then the cleaning water is sprayed and sprayed by the spray nozzle.

<Electrodeposition coating area C>
The electrodeposition coating area C is an area for forming an electrodeposition coating layer on the surface of the automobile body 1 on which the chemical conversion treatment layer is formed. In the electrodeposition coating area C shown in FIG. 3, in order from the upstream side of the electrodeposition coating line L, the first electrodeposition station 2, the fourth water washing station 3, the washing water removal station 4, the heat flow station 5, and the second electric power station. A landing station 6 and a fifth washing station 7 are arranged. Although not shown, a baking station for the electrodeposited film is provided next to the fifth washing station 7.

  The first electrodeposition station 2 is provided with a first electrodeposition tank 11 that stores an electrodeposition paint 9 in which the chemically converted automobile body 1 is immersed. In the first electrodeposition station 2, as shown in FIG. 4, the automobile body 1 immersed in the first electrodeposition tank 11 is used as a cathode, and the both sides and lower sides of the automobile body 1 are placed in the first electrodeposition tank 11. Cationic electrodeposition coating is performed using the counter electrode 10 provided on the side as an anode. The car body 1 is immersed in the electrodeposition paint 9 together with the hanger 45, but the transport device is not shown in FIG. In the present embodiment, the first electrodeposition tank 11 having the automobile body 1 as a cathode and the counter electrode 10 as an anode corresponds to the first electrodeposition means of the present invention.

  In the fourth water washing station 3, dip water washing and subsequent spray water washing of the automobile body 1 on which the paint of the first electrodeposition tank 11 is electrodeposited are performed. For this purpose, a dip washing tank 12 and a spray nozzle 13 are provided. The automobile body 1 is cleaned by being immersed in the cleaning water stored in the dip cleaning tank 12, and then the cleaning water is sprayed and cleaned by the spray nozzle 13. In the present embodiment, the dip washing tank 12 and the spray nozzle 13 correspond to the washing means of the present invention.

  A UF filtrate obtained by ultrafiltration (hereinafter sometimes referred to as "UF") of the electrodeposition paint of the first electrodeposition tank 11 is used as the rinse water of the above-mentioned dip rinse and spray rinse. For that purpose, a UF device 14 and a filtrate tank 15 for storing the UF filtrate obtained by the UF device 14 are provided. In order to reduce the loss of the electrodeposition paint, the UF filtrate in the filtrate tank 15 is supplied to the spray nozzle 13, the sprayed cleaning liquid is collected in the dip washing tank 12, and the overflow water from the dip washing tank 12 is discharged to the first electric The septic tank 11 collects it.

  At the cleaning water removal station 4, the cleaning water on the roof 1a (see FIGS. 5 to 9), which is a substantially horizontal cleaning water stagnating surface on which the cleaning water for cleaning the automobile body 1 stagnates, is not heated forcibly. Removed or reduced. In order to remove or reduce the washing water, a washing water removal promoting device 8 (washing water removal reducing means) is provided. The station will be described in detail later.

  In the heat flow station 5, the first electrodeposition coating film formed on the outer surface of the automobile body 1 near the counter electrode 10 of the first electrodeposition tank 11 heat-flows, and the first electrodeposition coating film on the near portion is heated. The car body 1 is heated so that the electric resistance of the carrousel is higher than the electric resistance of the first electrodeposition coating film formed at a portion distant from the counter electrode 10 of the first electrodeposition tank 11 such as the inner plate portion of the car body 1 Do. For this purpose, a coating film heat flow device 16 (heat flow means) is provided. The coating film heat flow device 16 includes a hot air heating furnace 17 to which hot air from a heater 18 is supplied. While the automobile body 1 passes through the hot air heating furnace 17, the first electrodeposition coating film is caused to heat flow. The specific configuration of the coating film heat flow device 16 will be described in detail later.

  The second electrodeposition station 6 is provided with a second electrodeposition tank 21 similar to the first electrodeposition tank 11, which stores an electrodeposition paint in which the automobile body 1 passed through the thermal flow station 5 is immersed. In the second electrodeposition station 6 as well as the first electrodeposition station 2, the automobile body 1 immersed in the second electrodeposition tank 21 is used as a cathode, and the counter electrode provided in the second electrodeposition tank 21 ( Cationic electrodeposition coating is performed with an anode (not shown). The electrodeposition paint of the second electrodeposition tank 21 of the present embodiment has the same component composition as the electrodeposition paint of the first electrodeposition tank 11, but the paint components of both electrodeposition tanks 11, 21 are different. There may be. In the present embodiment, the second electrodeposition tank 21 having the automobile body 1 as a cathode and the counter electrode as an anode corresponds to a second electrodeposition means.

  In the fifth water washing station 7, spray water washing, dip water washing, spray water washing, dip water washing and spray water washing are sequentially performed on the automobile body 1 on which the paint of the second electrodeposition tank 21 is electrodeposited. To that end, the first to third spray nozzles 22 to 24, the first dip washing tank 25, the fourth spray nozzle 26, the second dip washing tank 27 and the fifth spray nozzle are sequentially arranged from the upstream side of the electrodeposition coating line L 28 is provided.

  In the spray water washing by the first to fourth spray nozzles 22 to 24 and 26 and the dip water washing by the first dip water washing tank 25, UF obtained by ultrafiltration of the electrodeposition paint in the second electrodeposition tank 21 as washing water The filtrate is used. For that purpose, a UF device 31 and a filtrate tank 32 for storing the UF filtrate obtained by the UF device 31 are provided. Further, cleaning solution recovery tanks 33 and 34 for recovering the cleaning solution sprayed by each of the second spray nozzle 23 and the third spray nozzle 24 are provided. On the other hand, industrial water is used for dip water washing by the second dip water washing tank 27 and spray water washing by the fifth spray nozzle 28.

  In order to reduce the loss of the electrodeposition paint, the UF filtrate in the filtrate tank 32 is supplied to the first and fourth spray nozzles 22 and 26. The washing solution sprayed by the fourth spray nozzle 26 is collected in the first dip washing tank 25. Overflow water from the first dip washing tank 25 is collected in the cleaning liquid recovery tank 34 for the third spray nozzle 24. The cleaning solution of the cleaning solution recovery tank 34 is supplied to the third spray nozzle 24, and the overflow water from the cleaning solution recovery tank 34 is recovered in the cleaning solution recovery tank 33 for the second spray nozzle 23. The cleaning solution of the cleaning solution recovery tank 33 is supplied to the second spray nozzle 23, and overflow water from the cleaning solution recovery tank 33 is recovered in the second electrodeposition tank 21.

  In a baking station (not shown) after the fifth water washing station 7, the first electrodeposition coating film and the second electrodeposition coating film formed on the surface of the automobile body 1 are heated. For that purpose, a heating and curing furnace (hardening means) is provided.

<Washing water removal station 4>
The automobile body 1 is transported along the electrodeposition coating line L in the entire electrodeposition coating apparatus E including the washing water removal station 4 by an overhead conveyor (hanger type transport device). 5 and 6, the conveying device includes a guide rail 41 extending along the electrodeposition coating device E, and a roller 42 that engages the guide rail 41 with a roller 42 along the guide rail 41. It has the trolleys 43 and 44 which move forward and backward, and the hanger 45 which is suspended by the trolleys 43 and 44 and on which the car body 1 is mounted. In FIG. 5, 49 is an oil pan.

  The hanger 45 includes front and rear portal frames 47 and 48 suspended from the front and rear trolleys 43 and 44 via C-neck 46 for supporting the automobile body 1 from both sides. The front and rear portal frames 47 and 48 are connected by connecting bars 51 and 52. Receiving portions 53 and 54 for receiving the automobile body 1 are provided at lower ends of the front and rear portal frames 47 and 48.

  In the present embodiment, the cleaning water removal promoting device 8 of the cleaning water removal station 4 is configured by an air blowing device that blows air as gas toward the roof 1a. As shown in FIG. 7, the air blowing device includes three sets of two sets of two, that is, a total of six nozzle attachment pipes 55. That is, two sets of left and right nozzle mounting pipes 55 arranged at intervals in the horizontal direction orthogonal to the conveyance direction of the automobile body 1 form one set, and the three sets are the front, middle and rear in the conveyance direction. Side by side at intervals. The nozzles (blow nozzles) 60 attached to the left and right nozzle attachment pipes 55 are responsible for the removal of the washing water at the left and right portions of the roof 1a, respectively.

  The nozzle mounting pipe 55 is disposed above the place where the vehicle body 1 is mounted on and received by the receiving portions 53 and 54 of the hanger 45. Each nozzle attachment tube 55 includes three nozzle attachment portions. In this embodiment, as shown in FIG. 5, the nozzle 60 is attached to one of the nozzle attachment portions via a copper tube 60a. Each nozzle 60 has an air outlet opened downward so that air is blown to the roof 1 a of the vehicle body 1. As shown by arrows in FIG. 6, in the present embodiment, air blown from the nozzle 60 is blown toward the roof 1 a from above the portal frames 47 and 48 of the hanger 45. The air blowing speed to the roof 1a is approximately 20 m / sec to 25 m / sec. Note that the blowing speed in this case is the flow speed of the gas at a position where it is assumed that the roof 1a exists when the car body 1 is provided when gas is sent without the car body 1 being provided. .

  Next, air piping for supplying air to the nozzle 60 will be described. A first air supply pipe 56 extends from an air compressor (not shown) as an air source to the side of the vehicle body conveyance path at the washing water removal station 4. The first air supply pipe 56 is branched into three second air supply pipes 57 to 59 in order to supply air to the three sets of nozzle attachment pipes 55. Each of the second air supply pipes 57 to 59 is branched into third air supply pipes 57a to 59a and 57b to 59b in order to supply air to the left and right nozzle mounting pipes 55.

  The first air supply pipe 56 is provided with a manual on-off valve 61 and an air pressure meter 62. Each of the three second air supply pipes 57 to 59 is provided with a manual on-off valve 63 of the pipe line, a solenoid valve 64 for controlling the supply of air to the nozzle 60 and its stop, and an air pressure meter 65 .

  Thus, in the air blow device as the cleaning water removal promoting device, air is supplied to the nozzle 60 while the roof 1 a of the automobile body 1 passes in front of the air outlet of the nozzle 60, and the portal frame of the hanger 45 A control device 66 that controls the operation of the electromagnetic valve 64 according to the transport position of the automobile body 1 is provided so that the supply of air stops when 47 and 48 cross the front of the air outlet of the nozzle 60. For this control, an optical sensor (not shown) for detecting whether or not the roof 1a of the automobile body 1 passes in front of the air outlet of the nozzle 60 is provided, and the detection signal of the optical sensor controls the above control. Device 66 is provided.

<Heat flow station 5>
As shown in FIG. 8, the opposing side walls of the hot air heating furnace 17 have a double wall structure including an inner wall 71 and an outer wall 72. A tunnel furnace surrounded by an inner wall 71, a ceiling wall 73, and a bottom wall 74 is formed, and a guide rail 41 of a hanger type conveying device passes through the upper part of the tunnel furnace in the tunnel furnace longitudinal direction. The automobile body 1 is mounted on the hanger 45 and passes through the tunnel furnace.

  Between the inner wall 71 and the outer wall 72 of the tunnel furnace, hot air blowing means 76 having a heater, a blower motor and a blower fan is provided. Thus, the upper, middle, and lower nozzle boxes 77, 78, and 79 for blowing warm air toward the automobile body 1 mounted on the hanger 45 are provided on the opposed inner side walls 71.

  As shown in FIG. 9, the middle and lower nozzle boxes 78, 79 are spaced apart in the tunnel furnace longitudinal direction by a plurality of longitudinally slotted first hot air outlets 81 that blow out hot air toward the side surface of the automobile body 1. Have prepared. The upper nozzle box 77 includes a second hot air outlet 82 in the form of a cylindrical hole that blows out hot air toward the roof 1 a that is the stagnation surface of the washing body of the automobile body 1.

  Here, the distance from the second warm air outlet 82 to the roof 1 a is longer than the distance from the first warm air outlet 81 to the side surface of the car body 1. Therefore, the hot air blowing speed of the second hot air outlet 82 is set higher than the hot air blowing speed of the first hot air outlet 81 so that the hot air reliably reaches the roof 1a. Moreover, in order to improve the directivity of warm air, the 2nd warm air blower outlet 82 is formed in the cylinder hole shape. The blowing speed of the warm air to the body side surface and the roof 1a of each of the first warm air outlet 81 and the second warm air outlet 82 is about 5 m / sec to 15 m / sec.

  An air suction port 83 for sucking the heated air in the tunnel furnace and circulating it to the hot air blowing means 76 is opened at the upper part of the inner wall 71.

<Electrodeposition coating method>
In the first water washing station A1, the car body 1 before removing the dirt or oil on the surface is dipped in the washing water of the dip water washing tank and then pulled up to perform dip water washing or discharge it from the spray nozzle Spray water washing is performed by spraying spray water.

  The automobile body 1 is transported from the first water washing station A1 to the degreasing washing station A2 while being mounted on the hanger 45. At the degreasing and washing station A2, the washed automobile body 1 is immersed in the degreasing solution A12 of the degreasing tank A13. The degreasing solution A12 is vibrated by the ultrasonic waves of the ultrasonic vibrator A14 disposed in the lower part of the degreasing tank A13, and bubbles generated by this vibration collide with the automobile body 1 and rupture, whereby the automobile body 1 is degreased and washed. (Degreasing process). Since the automobile body 1 is degreased and cleaned by the vibration of ultrasonic waves, the portion not exposed to the outside of the automobile body 1 can be sufficiently degreased and cleaned as compared with the cleaning using water pressure or the like by spray.

  The automobile body 1 is transported from the degreasing washing station A2 to the second washing station A3 while being mounted on the hanger 45. In the second water washing station A3, the degreased automobile body 1 is immersed and pulled up in the washing water of the first dip water washing tank, and dip water washing is performed, and then the first spray nozzle sprays the washing water. Spray water washing is performed, followed by dip water washing by a second dip water washing tank and spray water washing by a second spray nozzle.

  The automobile body 1 is transported from the second water washing station A3 to the chemical conversion treatment station B1 while being mounted on the hanger 45. In the chemical conversion treatment station B1, the cleaned automobile body 1 is immersed in the zirconium oxide treatment liquid of the chemical conversion tank (chemical conversion step). Thus, an amorphous thin film chemical conversion treatment layer is formed on the surface of the automobile body 1. Therefore, the formation sludge which generate | occur | produces by a chemical conversion treatment can be suppressed and the load to an environment can be reduced.

  The automobile body 1 is transported from the chemical conversion treatment station B1 to the third water washing station B2 while being mounted on the hanger 45. In the third water washing station B2, the automobile body 1 on which the chemical conversion treatment layer is formed is dipped and pulled up in the washing water of the dip water washing tank, and dip water washing is performed, and then the spray nozzle sprays the washing water. Spray washing is performed.

  At the first electrodeposition station 2, as shown in FIG. 4, the cleaned automobile body 1 is immersed in the electrodeposition paint 9 of the first electrodeposition tank 11, and a DC voltage is applied between the automobile body 1 and the counter electrode 10. Is applied (first electrodeposition step). Thereby, a 1st electrodeposition coating film is formed in the outer-plate part and inner-plate part of the motor vehicle body 1. As shown in FIG. The first electrodeposition coating film is thickly formed on the portion near the counter electrode 10 where the current density is high like the outer plate portion, and thinly formed on the portion where the current density is low far from the counter electrode 10 like the inner plate portion The

  The automobile body 1 is transported from the first electrodeposition station 2 to the fourth washing station 3 in a state of being mounted on the hanger 45. In the fourth water washing station 3, the automobile body 1 on which the first electrodeposition coating is formed is dipped and pulled up in the washing water of the dip water washing tank 12, and dip water washing (dip water washing step) is performed, and then Spray water washing (spray water washing process) is performed by spraying of the washing water by the spray nozzle 13 (water washing process).

  The automobile body 1 is transported from the fourth water washing station 3 to the washing water removing station 4 while being mounted on the hanger 45. In the washing water removal station 4, when the cleaned roof 1 a of the automobile body 1 passes in front of the air outlet of each nozzle 60, the electromagnetic valve 64 related to the nozzle 60 is opened and the air enters the roof 1 a. Sprayed (wash water removal reduction process). By this air blowing, most of the washing water stagnating on the roof 1a is blown away and removed. Therefore, it is advantageous to prevent the formation of recesses in the first electrodeposition coating in the subsequent heat flow step. The removal or reduction of the washing water is preferably performed unheated or in a low atmosphere so as not to cause an unintended heat flow of the first electrodeposition coating. In addition, when the frames 47 and 48 of the hanger 45 pass in front of the air outlet of the nozzle 60, the air blowing stops. Accordingly, it is possible to prevent oil and dust adhering to the hanger 45 from being blown off by air and adhering to the first electrodeposition coating film.

  The automobile body 1 is conveyed from the washing water removal station 4 to the heat flow station 5 while being mounted on the hanger 45, and is carried into the hot air heating furnace 17, that is, into the tunnel furnace. While passing through the tunnel furnace, the first electrodeposited film on the outer plate portion of the automobile body 1 is heated and heated by the warm air blown out from the first warm air outlet 81 and the second warm air outlet 82. (Heat flow process).

  The heat flow of the first electrodeposition coating film is performed by blowing hot air having a temperature lower than the baking temperature (150 ° C. to 180 ° C.) of the first electrodeposition coating film to the automobile body 1. Since it is not heating by radiation but heating by warm air, even if cleaning water remains on the surface of the first electrodeposition coating film, the cleaning water is quickly removed. It is advantageous in preventing formation of a recess on the surface.

  Further, the heat flow of the first electrodeposition coating film is, for example, a temperature of 70 ° C. to 110 ° C. for the first electrodeposition coating film formed on a portion near the counter electrode 10 of the automobile body 1 in the first electrodeposition tank 11 It is preferable to carry out heating for several minutes. If the heating temperature is low, or if the heating time is short, the heat flow of the first electrodeposition coating near the counter electrode 10 of the automobile body 1 becomes insufficient, and the electrical resistance does not sufficiently increase. This is disadvantageous in forming a second electrodeposition coating film having a desired thickness at a position far from the counter electrode 10 of the automobile body 1. On the other hand, when the heating temperature is high, or when the heating time is long, the first electrodeposition coating film that is thinly formed at a site far from the counter electrode 10 of the automobile body 1 heat-flows into a dense coating film, that is, , The electrical resistance is increased, which is disadvantageous for the formation of the second electrodeposition coating film on this distant site.

  Since the warm air from the second warm air outlet 82 is directed to the roof 1a, even if the washing water remains on the roof 1a, the washing water quickly evaporates. That is, the boundary between the part wetted with the washing water of the roof 1a and the dry part disappears quickly. Therefore, the temperature of the first electrodeposition coating rises substantially uniformly over the entire surface of the roof 1a. Therefore, it is avoided that the first electrodeposition coating is partially formed with portions having different amounts of volume contraction to cause local depressions.

  Since the warm air from the first and second warm air outlets 81 and 82 is applied to the outer plate portion of the automobile body 1, the first electrodeposition coating film on the outer plate portion heat-flows, but the first electric power on the inner plate portion. The amount of heat received by the coated film is small. Therefore, the degree of heat flow of the first electrodeposited film on the inner plate portion is smaller than that of the first electrodeposited film on the outer plate portion. There is almost no heat flow in the deep part of the inner plate part seen from the outer plate part. Therefore, the electrical resistance of the first electrodeposition coating film on the outer plate portion is higher than that of the first electrodeposition coating film on the inner plate portion.

  The automobile body 1 is transported from the thermal flow station 5 to the second electrodeposition station 6 in a state of being mounted on the hanger 45. At the second electrodeposition station 6, the car body 1 having a heat flow applied to the first electrodeposition coating is immersed in the electrodeposition paint of the second electrodeposition tank 21, and a direct current is applied between the car body 1 and the counter electrode. A voltage is applied (second electrodeposition process). Thereby, a 2nd electrodeposition coating film is formed in the outer-plate part and inner-plate part of the motor vehicle body 1. FIG. In this case, the first electrodeposition film on the outer plate has a higher electrical resistance than the first electrodeposition film on the inner plate due to the heat flow described above, so the inner plate is better than the outer plate. A large amount of electrodeposition paint of the second electrodeposition tank 21 adheres to the part. Therefore, by adjusting the immersion time of the automobile body 1 in the electrodeposition paint of the second electrodeposition tank 21, etc., the thickness of the electrodeposition coating on the outer and inner plate portions (the first electrodeposition coating and the second It is easy to control the thickness of the two electrodeposition coating films) to a desired film thickness.

  The automobile body 1 is transported from the second electrodeposition station 6 to the fifth washing station 7 in a state of being mounted on the hanger 45. In the fifth washing station 7, spray washing with the first to third spray nozzles 22 to 24 with respect to the automobile body 1 on which the second electrodeposition coating is formed, dip washing with the first dip washing tank 25, the fifth Spray washing with the four spray nozzles 26, dip washing with the second dip washing tank 27, and spray washing with the fifth spray nozzle 28 are sequentially performed.

  The automobile body 1 is transported from the fifth water washing station 7 to the baking station of the electrodeposition coating film in a state of being mounted on the hanger 45, and the first electrodeposition coating film and the second electrodeposition coating formed on the surface of the automobile body 1 The film is baked and cured (curing step).

<Other Embodiments>
As a hanger for transporting an automobile body, a C-shaped hanger that supports the automobile body 1 from one side can also be adopted. In this case, at the cleaning water removal station 4, second air supply pipes 57 to 59 are disposed on the opposite side of the C-shaped hanger with the automobile body 1 interposed therebetween, and the second air supply pipes 57 to 59 The air supply pipe can be extended toward an intermediate position between the position where the upper frame passes and the position where the roof 1a of the automobile body 1 passes, and the nozzle 60 can be arranged at the intermediate position. Thereby, since the upper frame of the hanger does not pass under the nozzle 60, air can be blown continuously to the roof 1a when the roof 1a passes under the nozzle 60.

  When the C-type hanger is adopted, the position where the upper frame of the C-type hanger passes and the position where the roof 1a of the car body 1 passes from the opposite side of the C-type hanger across the car body 1 also in the heat flow station. The hot air outlet pipe can be extended to an intermediate position between them. Thereby, since the 2nd warm air blower outlet 82 can be arrange | positioned below right above the position where the roof 1a passes, it becomes advantageous when evaporating and removing the washing water remaining on the roof 1a quickly.

  In the above embodiment, the first electrodeposition paint and the second electrodeposition paint have the same composition, but an electrodeposition paint having a composition different from that of the first electrodeposition paint is adopted as the second electrodeposition paint. You can also.

  In the above embodiment, degreasing cleaning is performed using the degreasing tank A13 in which a plurality of ultrasonic transducers A14 are disposed in the degreasing cleaning station A2, but a degreasing bath not including the ultrasonic transducers is employed. It can also be done.

  In the fourth washing station 3, spray water washing is performed after dip water washing, but dip water washing can also be performed after the spray water washing. The electrodeposition paint 9 can be efficiently cleaned by performing spray water washing after dip water washing.

  Moreover, in the said embodiment, although air is sprayed on the roof 1a in the wash water removal station 4, wash water should just be removed from the roof 1a, and methods other than blowing air can also be employ | adopted.

  Moreover, in the said embodiment, although the nozzle 60 is attached to one of the nozzle attachment parts of each nozzle attachment pipe 55 in the washing water removal promotion apparatus 8, a nozzle can also be attached to a some nozzle attachment part.

  In the above embodiment, the zirconium oxide treatment liquid is used as the chemical conversion solution in the chemical conversion treatment station B1, but any chemical solution may be used as long as the chemical conversion treatment layer of non-crystalline thin film is formed on the automobile body 1 Solutions other than the zirconium treatment liquid can also be employed.

E Electrodeposition coating equipment L Electrodeposition line A Degreasing and cleaning area B Chemical conversion area C Electrodeposition area 1 Automobile body (object)
1a Roof (wash water stagnant surface)
A12 Degreasing solution A13 Degreasing tank A14 Ultrasonic transducer 8 Cleaning water removal promoting device 10 Counter electrode 12 Dip washing tank 13 Spray nozzle 16 Coating film heat flow device 41 Guide rail 45 Hanger 60 Nozzle 64 Solenoid valve 66 Control device

Claims (17)

A chemical conversion treatment step of forming a chemical conversion treatment layer on the surface of the substrate;
An electrodeposition coating method comprising: an electrodeposition coating step of forming an electrodeposition coating layer on the surface of the substrate on which the chemical conversion treatment layer is formed after the chemical conversion treatment step;
The chemical conversion treatment process is as follows:
A chemical conversion step of immersing the object to be coated in a chemical conversion solution to form a conversion treatment layer of an amorphous thin film on the surface of the object to be coated;
The above electrodeposition coating process is
A first electrodeposition step of applying a DC voltage between the object to be coated on which the chemical conversion treatment layer is formed and the counter electrode in a first electrodeposition tank to form a first electrodeposition coating film on the object to be coated; ,
The electrical resistance of the first electrodeposition coating film formed on the portion near the counter electrode of the coated object on which the first electrodeposition coating film is formed after the first electrodeposition step is formed on a portion far from the counter electrode Performing a heat flow of the first electrodeposition film so as to be higher than the electrical resistance of the first electrodeposition film;
After the heat flow step, in the second electrodeposition tank, a DC voltage is applied between the object to be coated and the counter electrode to which heat flow has been applied to the first electrodeposition coating film, and the second electrodeposition is applied to the object A second electrodeposition step of forming a coating film;
The electrodeposition coating method characterized by including the hardening process which heat-hardens the said 1st electrodeposition coating film and the 2nd electrodeposition coating film after the said 2nd electrodeposition process. In the electrodeposition coating method according to claim 1,
The electrodeposition coating step is performed after the first electrodeposition step and before the heat flow step.
A water-washing step of washing the substrate on which the first electrodeposition coating film has been formed after the first electrodeposition step;
The method further includes a cleaning water removal and reduction step for removing or reducing the cleaning water on the substantially horizontal cleaning water stagnant surface of the object to be cleaned, in which the cleaning water for cleaning is stagnated after the above-mentioned water cleaning step. Dressing method. In the electrodeposition coating method according to claim 2,
The cleaning water removal reducing step is a step of spraying a gas onto the washing water stagnation surface so that the washing water is excluded from the washing water stagnation surface. In the electrodeposition coating method according to claim 2 or 3,
The water washing step
A dip water-washing step of immersing the object to be coated on which the first electrodeposition coating film is formed in the washing water stored in a dip water-washing tank;
An electrodeposition coating method comprising: a spray water washing step of spraying washing water on an object on which the first electrodeposition coating film is formed before or after the dip water washing step. In the electrodeposition coating method according to any one of claims 1 to 4,
The heat flow in the heat flow step is performed by spraying warm air at a temperature lower than the baking temperature of the first electrodeposition coating film on the object to be coated. In the electrodeposition coating method according to claim 5,
The heat flow in the heat flow step is a state in which the first electrodeposition coating film formed on the portion near the counter electrode of the object to be coated in the first electrodeposition tank is heated from 70 ° C. to 100 ° C. for several minutes The electrodeposition coating method characterized by performing so that it may become. In the electrodeposition coating method according to any one of claims 1 to 6,
The formation solution used in the said formation process is a zirconium oxide processing liquid, The electrodeposition coating method characterized by the above-mentioned. In the electrodeposition coating method according to any one of claims 1 to 7,
Before the chemical conversion treatment step, the method further comprises a degreasing and washing step of removing dirt or oil on the surface of the object to be coated,
The above degreasing and cleaning process is
A degreasing tank storing the degreasing solution is provided in advance,
The object to be coated prior to removing surface dirt or oil is immersed in the degreasing solution, and the object to be coated is ultrasonically vibrated by the ultrasonic transducer disposed under the degreasing tank. An electrodeposition coating method comprising a degreasing step of degreasing and cleaning. In the electrodeposition coating method according to any one of claims 2 to 8,
The electrodeposition coating method, wherein the object to be coated is an automobile body, and the washing water stagnation surface is a roof of the automobile body. A chemical conversion treatment means for forming a chemical conversion treatment layer on the surface of the substrate;
An electrodeposition coating apparatus comprising: an electrodeposition coating means for forming an electrodeposition coating layer on the surface of a substrate on which the chemical conversion treatment layer is formed,
The chemical conversion means is
It has a chemical conversion tank in which a chemical conversion solution is stored, and includes chemical conversion means for immersing the coating object in the chemical conversion solution to form a conversion treatment layer of an amorphous thin film on the surface of the coating object,
The above electrodeposition coating means
A first electrodeposition comprising a first electrodeposition tank and applying a DC voltage between a substrate to which the chemical conversion treatment layer is formed and a counter electrode to form a first electrodeposition coating film on the substrate Means,
The first electrodeposition coating film formed at a site far from the counter electrode where the electrical resistance of the first electrodeposition coating film formed at a site near the counter electrode of the article on which the first electrodeposition coating film is formed Heat flow means for heat flow of the first electrodeposition coating film so as to be higher than the electric resistance of
A second electrodeposition coating film is formed on the coating object by applying a DC voltage between the coating object having a second electrodeposition tank and the first electrodeposition coating film subjected to heat flow and a counter electrode. A second electrodeposition means to form;
An electrodeposition coating apparatus comprising: a curing means for heat-curing the first electrodeposition coating film and the second electrodeposition coating film. In the electrodeposition coating apparatus according to claim 10,
The electrodeposition coating means is disposed between the first electrodeposition means and the heat flow means.
Washing means for washing the substrate on which the first electrodeposition coating film is formed;
Washing water removal reducing means for removing or reducing the washing water on the washing water stagnation surface, which is substantially horizontal of the object to be coated, in which the washing water for washing in the washing means stagnates. Dressing equipment. In the electrodeposition coating apparatus according to claim 11,
The electrodeposition coating apparatus, wherein the cleaning water removal reducing means includes a blow nozzle that blows gas onto the cleaning water stagnation surface so that the cleaning water is excluded from the cleaning water stagnation surface. An electrodeposition coating apparatus according to claim 11 or 12,
The washing means is
A dip water washing tank storing washing water for immersing the substrate on which the first electrodeposition coating film is formed;
An electrodeposition coating apparatus comprising: a spray nozzle for spraying washing water to a substrate on which the first electrodeposited film has been formed before or after the dip water washing tank. In the electrodeposition coating apparatus according to any one of claims 10 to 13,
The heat flow means includes a heat flow device that blows hot air having a temperature lower than the baking temperature of the first electrodeposition coating film on the article from which the washing water has been removed or reduced. Painting equipment. In the electrodeposition coating device according to any one of claims 10 to 14,
An electrodeposition coating apparatus characterized in that a zirconium oxide treatment liquid is stored as the chemical conversion solution in the chemical conversion tank. In the electrodeposition coating device according to any one of claims 10 to 15,
Before the above chemical conversion treatment means, it further comprises a degreasing and washing means for removing dirt or oil on the surface of the object to be coated,
The above degreasing and cleaning means is
A degreasing tank in which a degreasing solution is stored, an object to be coated before removing dirt or oil on the surface, is immersed in the degreasing solution, and the degreasing is performed by an ultrasonic vibrator disposed at a lower portion of the degreasing tank. An electrodeposition coating apparatus comprising degreasing means for degreasing and cleaning the substrate by ultrasonic vibration of a solution. In any one of Claim 12, Claim 13, which refers to Claim 12, Claim 14, which refers to Claim 12, Claim 15, which refers to Claim 12, or Claim 16, which refers to Claim 12. In the electrodeposition coating apparatus described,
The object to be coated is a car body, and the washing water stagnant surface is a roof of the car body,
A guide rail extending from the flush means to the heat flow means;
A hanger suspended from the guide rail and carrying the automobile body and transported from the washing means to the heat flow means,
The blow nozzle is arranged above the place where the automobile body is mounted on the hanger and passes through, with the gas outlet facing downward so that the gas is blown to the roof of the automobile body,
A solenoid valve for controlling supply and stop of gas to the blow nozzle;
The gas is supplied to the blow nozzle while the roof of the automobile body passes in front of the gas outlet of the blow nozzle, and the frame constituting the hanger crosses the front of the blow nozzle of the blow nozzle. And a control device for controlling the operation of the solenoid valve in accordance with the transport position of the vehicle body so as to stop the supply of gas.

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