JP2009185337A - Automatic control method for electrodeposition film thickness - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a coating method capable of easily and surely obtaining electrodeposition coating films complying with required quality even if workpieces different in area. workpieces different in material or workpieces different in required film thicknesses are film-deposited continuously in irregular order. <P>SOLUTION: In the electrodeposition coating line in which a plurality of hangers/ workpieces are continuously conveyed and the workpieces are simultaneously made to fully sink in an electrodeposition tank equipped with energizing bus bars and electrode plates, the electrodeposition coating method comprises introducing a plurality of the energizing bus bars changed in lengths, a plurality of current collectors corresponding to the bus bars and hooks for suspending hangers into the electrodeposition tank, selecting the positions of the hooks for suspending the hanger by the hanger, and controlling the energizing time, thereby assuring the target film thickness. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an electrodeposition coating method for coating using automobile parts, electrical parts, and other hangers, and in particular, objects to be coated with different required coating thicknesses are mixed and irregularly and continuously conveyed to an electrodeposition tank. In this case, it is an electrodeposition coating method that can easily and surely obtain an optimum required coating film thickness according to the size of the object to be coated and the type of metal.

To apply electrodeposition coating according to the required quality to the objects with different coating area, material metal type, and required coating film thickness, such as automobile body and automobile parts, (1) In the tank filled with electrodeposition coating It is common to apply electrodeposition by applying different DC voltages depending on the purpose between the diaphragm electrode and the bare electrode installed on the left and right, top and bottom, and the object to be coated, followed by washing with water and baking. . In addition, (2) a method of dividing the energization bus bar into a plurality of parts and providing a limit switch to perform complicated energization time control is also implemented. Patent Document 1 and Patent Document 2 correspond to this. Furthermore, (3) a method of conducting energization time control by introducing a plurality of energization bus bars and energization time controllers having the same length and combining energization connection and energization interruption is also partly implemented. Patent Document 3 corresponds to this.
JP 2002-30486 A JP 63-145798 A JP-A-10-219497

  Problems in the conventional methods described in the above (1), (2), and (3) will be described. In the method of applying by applying different voltages according to the purpose described in (1), for example, when the shape of the object to be coated is changed, or when the required coating film thickness is changed, the coating voltage is set. If the change is forgotten, the film thickness will be excessive than the required coating film thickness, or the film thickness will be reduced. When the film thickness is excessive, problems such as loosening of screw parts and bolts or increase in the amount of paint used occur.

  On the other hand, in the method of providing a limit switch described in (2) and performing complex energization time control, the equipment cost for limit switch control is high, the management becomes complicated, and an electric power for exclusively painting a small area to be coated. It is particularly difficult to introduce in the coating line.

  In addition, the method of introducing a plurality of energized bus bars and energizing time controllers having the same length described in (3) is complicated in energizing method, has high equipment costs (such as energizing controllers), and can be applied continuously. There is a limit to the types of objects to be coated and the required film thickness, and it is difficult to coat various kinds of objects to be coated alternately.

  The present invention changes the length in an electrodeposition coating line that continuously conveys a plurality of hangers / objects and simultaneously immerses the object in an electrodeposition tank equipped with a current-carrying busbar and an electrode plate. Introducing multiple energized bus bars and multiple current collectors and hooks for hanging hangers corresponding to the bus bars, and selecting the position of the hook to be hung for each hanger controls the energization time and ensures the target film thickness It relates to an electrodeposition coating method that can be performed.

  As described above, when the electrodeposition coating method of the present invention is used, a coating having a different area, a coating having a different material, or a coating having a different required film thickness can be used without artificially changing the coating voltage. The electrodeposition coating film according to the required quality can be obtained reliably and easily by continuously coating the objects in an irregular order.

  In addition, with respect to an object to be coated which has been easily thickened by a conventional coating method, an appropriate film thickness can be secured by the electrodeposition coating method of the present invention, so that the amount of paint used can be reduced. Furthermore, in the conventional coating method, it is necessary to continuously coat the same type and the same material, but if the electrodeposition coating method of the present invention is used, it is not always necessary to continuously coat, for example, alternately or not. Even if the object to be coated is changed to the rule, it is possible to ensure the target coating film thickness.

The conventional coating method and the coating method of the present invention will be described below in detail with reference to the drawings and examples.
FIG. 1 shows a conventional electrodeposition coating tank, in which only one energizing bus bar is mounted. FIG. 2 shows a conventional electrode plate, in which only one set of current collectors and hooks corresponding to the bus bar is mounted. Before performing electrodeposition coating, the object to be coated is hung on a hook using a hanger, and then the electrode plate is transported to the electrodeposition coating tank. Painted. At this time, electricity flows to the energized bus bar, current collector, hook, hanger, and article to be coated.

  In such a conventional coating method, in order to apply electrodeposition coating according to the required quality to the coated object area, material metal type, required coating film thickness such as automobile body, automobile parts, etc., respectively, It is necessary to individually set an appropriate voltage for each coating object, and the coating film thickness of the coating object is controlled by energizing controller, limit switch, etc., by energizing time control, ON / OFF of electrode, etc. . Also, in painting various types of objects such as automobile parts, there are many painting lines in which the set voltage is artificially changed for each object. In such an electrodeposition coating line, when the voltage change for each object to be coated is not performed or forgotten, there is a problem that an excessive film thickness or a thin film is formed. When the film thickness becomes excessive, problems such as loosening of screw parts, bolts, and increase in the amount of paint used occur. In the case of a thin film, there is a problem that the rust prevention performance is lowered, and the required quality standard is satisfied and it becomes impossible to ship the coated product. In addition, in order to apply electrodeposition coating according to the required quality to the coated objects with different coating area, material metal type, and required coating film thickness, create a space between each coated object, It is necessary to prevent the objects to be coated from being electrodeposited at the same time, which causes a problem that production efficiency is lowered.

  On the other hand, FIG. 3 shows the electrodeposition coating tank of the present invention, in which four energized bus bars having different lengths are mounted. FIG. 4 shows an electrode plate according to the present invention, in which four collectors and four hooks are mounted corresponding to each bus bar. Four types of objects to be coated are hung on predetermined hooks, and then the electrode plate is transported to the electrodeposition coating tank. The corresponding energized bus bar and the current collector are brought into contact with each other, and electricity is applied to conduct electrodeposition coating. .

  When electrodeposition coating is carried out using the electrodeposition coating equipment according to the present invention, it is possible to control the current by controlling the energization time by means of a conventional energization controller, limit switch, etc., and by turning on / off the electrode (+ electrode). There is no need to control the coating thickness of the coating. In addition, in various types of coatings such as automobile parts, the set voltage is artificially changed for each coating, but the desired film thickness control can be achieved without implementing this. .

Hereinafter, an embodiment of the present invention will be described in more detail with reference to the drawings in comparison with a conventional type.
FIG. 1 and FIG. 2 show a conventional coating system, in which an object to be coated is placed on the upper part of an electrodeposition tank using a hanger that holds the object to be continuously conveyed, and is energized through an energizing bus. In order to ensure the target film thickness, the voltage is artificially changed in accordance with the target film thickness. In this coating method, it is only possible to continuously coat only the objects with the same area, material type, and required film thickness. It is impossible to paint objects in an irregular order. In addition, if forgetting to change the coating voltage of the rectifier to ensure an appropriate film thickness that varies depending on the object to be coated, there is a problem that the film thickness becomes too thick or too thin.

The present invention will be described with reference to FIGS. 3, 4, and 5.
In FIG. 3, the electrodeposition coating apparatus of the present invention differs from the conventional type in that a plurality of energized bus bars 1 to 4 for power feeding are installed in the upper part of the electrodeposition tank. Each bus bar has a different length and is set to obtain different energization times. The standard energization bus bar has a standard length and a standard energization time, and the non-standard energization bus bar is a short energization bus bar, and is set so that the energization time is shorter than the standard.

  Further, the plurality of current collectors 1 to 4 installed on the upper part of the hanger in FIG. 4 are brought into contact with the plurality of current-carrying bus bars 1 to 4 shown in FIG. The current collectors 1 to 4 in FIG. 4 are connected to the hooks 1 to 4. For example, the hook 1 in FIG. 4 is connected to the current collector 1, and the current collector 1 comes into contact with the current-carrying bus bar 1 in FIG. Therefore, the energization time is automatically changed by freely selecting the positions 1 to 4 of the hook on which the hanger is applied, and even if the coating area and material type of the object to be coated are different as shown in FIG. It is an electrodeposition coating method that can accurately obtain the film thickness. On the other hand, as shown in FIG. 6, the conventional coating method cannot be applied continuously unless the coating area and shape of the object to be coated are the same.

  In addition, the method of adjusting the length of the energized bus bar is divided into a plurality of parts other than the standard length bus bar as shown in FIG. 5, and is connected by an electric cord and a breaker, and optionally by turning the breaker on and off. Fine adjustment (substantial adjustment of the length of the bus bar) of the energizing time between the energizing bus bars is possible.

  Although the following can be illustrated about the specific content of the electrodeposition coating apparatus of this invention, it is not limited to this. The length of the current-carrying bus bar is 2 to 30 m, and the number of current-carrying bus bars varies depending on the installation location of the bus bar, but it can be installed regardless of the upper and side surfaces, and about 4 to 16 bus bars can be installed. With respect to the standard coating voltage, a coating voltage of (50 to 400 V) is set for a coating object having the maximum coating film thickness required for each coating object. The energization time is 30 to 480 seconds, and the bath liquid temperature of the electrodeposition paint is generally used in the range of 25 to 35 ° C. Regardless of the shape, material type, and area of the object, all conductive metals can be painted.

  The electrodeposition coating method of the present invention can be used for all electrodeposition coatings regardless of the anion type or cation type, and regardless of the resin type used such as epoxy type or acrylic type.

  Specific examples of equipment and specific examples of coating conditions will be illustrated below to compare the conventional type with the present invention and clarify the superiority of the present invention.

(A) Conventional coating equipment, examples of coating conditions;
Electrodeposition paint type; Epoxy-type cationic electrodeposition paint name: Saxade # 80V black (manufactured by DuPont Shinto Automotive Systems Co., Ltd.)
Electrodeposition bath temperature: 28 ° C
Washing after electrodeposition; 3 steps of UF water washing + 1 step of pure water washing baking drying; 180 ° C. setting × 30 minutes pass energizing time; 180 seconds energizing bus bar length; 3 m
Conveyor speed: 1 m / min Coating voltage: (Set according to the required film thickness for each workpiece)
Substrate A (material, iron, area-large) = 200 V (required film thickness 30 ± 2 μm)
Coating object B (material, iron, area-medium) = 180 V (required film thickness 20 ± 2 μm)
Object C (material, iron, area-small) = 160 V (required film thickness 15 ± 2 μm)
Object D (material, stainless steel area-small) = 140 V (required film thickness 20 ± 2 μm)

For the articles A, B, C, and D, the coating film thickness is 30 μm, 20 μm, 15 μm,
A coating film thickness of 20 μm was obtained. However, if you forget to change the coating voltage, there is a problem that the coating film thickness becomes excessive or thin. For example, when the object C is applied at 200V, the coating film thickness is 24 μm, when the object D is applied at 180V, the coating film thickness is 27 μm, and when the object A is applied at 140V, the coating film thickness is 14 μm.

Specific examples of the present invention are illustrated below.
(B) Coating equipment and coating condition examples of the present invention;
Electrodeposition paint type; Epoxy-type cationic electrodeposition paint name: Saxade # 80V black (manufactured by DuPont Shinto Automotive Systems Co., Ltd.)
Liquid temperature: 28 ° C
Washing after electrodeposition; UF washing 3 steps + pure water washing 1 step baking drying; 180 ° C. setting × 30 minutes pass energizing time; (Set according to the required film thickness for each coated object)
Object A = 180 seconds (required film thickness 30 ± 2 μm)
Substrate B = 150 seconds (required film thickness 20 ± 2 μm)
Object C = 120 seconds (required film thickness 15 ± 2 μm)
Object to be coated D = 90 seconds (required film thickness 20 ± 2 μm)
Energized bus bar length;
For object A = 3m
For object B = 2.5m (length can be adjusted individually)
For object C = 2.0m (length can be adjusted individually)
For object D = 1.5m (length can be adjusted individually)
Conveyor speed: 1 m / min painting voltage: 200 V fixed (coating objects A to D, all constant)

  The hanger of the object to be coated A is hung on the hook 1, the hanger of the object B to be hung on the hook 2, the hanger of the object C to be hung on the hook 3, The hanger is hung on the hook 4. The energized bus bar and the hook are connected to the energized bus bar 1 ⇔ hook 1, energized bus bar 2 ⇔ hook 2, energized bus bar 3 ３ hook 3, and energized bus bar 4 ⇔ hook 4, respectively, through current collection. As a result, each object to be coated is energized only for the time required for electrodeposition and electrodeposition coating is performed. Under the above-mentioned coating conditions, the coating film thicknesses obtained for the actually coated objects A, B, C, and D were 30 μm, 20 μm, 15 μm, and 20 μm, respectively, and the results satisfy the required quality. .

  As described above, when the electrodeposition coating method of the present invention is used, there is no need to artificially change the coating voltage, and the electrodeposition coating for automobile bodies, automobile parts, home appliances, steel furniture, etc. has different areas. An electrodeposition coating film corresponding to the required quality can be obtained reliably and easily by continuously coating the coating material, the coating material with different materials, or the coating material with different required film thickness in an irregular order.

It is an example of the side view of the electrodeposition coating tank used for the conventional coating. It is an example of the electrode plate used for the conventional painting. It is an example of the side view of the electrodeposition coating tank used for this invention. It is an example of the electrode plate used for this invention. It is an example of the length adjustment method of an electricity supply bus bar. It is an example of the side view of the state by which the to-be-coated object is electrodeposition-coated in the conventional painting. It is an example of the side view of the state by which the to-be-coated object is electrodeposition-coated in this invention.

Claims (3)

  Objects with different areas, materials with different materials, or multiple objects with different required film thicknesses are transported irregularly and continuously. In the electrodeposition coating line that is completely submerged in the electrodeposition tank provided, multiple energized busbars with different lengths and multiple current collectors corresponding to the busbars and hooks for hanging hangers are introduced and hung for each hanger. An electrodeposition coating method that can control the energization time and secure the target film thickness by selecting the position of the hook to be lowered.   The electrodeposition coating method according to claim 1, wherein 2 to 10 hooks for hanging a current-carrying bus bar, a current collector, and a hanger are introduced.   The electrodeposition coating method according to claim 1, wherein 3 to 6 hooks for hanging a current-carrying bus bar, a current collector, and a hanger are introduced.

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