JP2732148B2 - Electrocoating equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial application field) The present invention relates to an electrodeposition coating apparatus, more specifically, an article to be coated is placed on a pallet or the like or stacked on a support structure frame, and the loaded The present invention relates to an electrodeposition coating apparatus of a type in which a coated article is suspended in a conveyor while being immersed in a paint tank and transferred.

That is, the present invention is applied to a case where a product is simultaneously and continuously coated in the electrodeposition coating of a small product, particularly an automobile frame and other parts.

(Prior Art) In recent years, with the remarkable diversification of product demand, many industrial products are required to have a variety of production types in a small quantity. For this reason, in the field of electrodeposition coating, a coating method suitable for such a style is required. Has been developed.

Electrodeposition coating of automobile bodies is mainly performed by the slipper dip method.Recently, different types of automobile bodies are hung together on a conveyor on the same painting line, and these are sequentially immersed in a paint tank and transferred. In this case, a mixed coating method in which the electrodeposition coating is performed continuously is adopted.

In this mixed paint mode, the conditions and paint specifications for electrodeposition coating of automobile bodies differ depending on the vehicle type, so even if simultaneous electrodeposition coating processing is performed, regardless of the vehicle type, the electrodeposition coating film is always Thickness adjustments are needed to make the thickness appropriate and uniform over the entire surface.

Conventionally, various methods have been proposed for the purpose of adjusting the film thickness. A typical example is a method of adjusting the amount of electric charge to be applied to an article to be coated according to the characteristics of an electrodeposition coating (Japanese Patent Application No.
-58673 / Japanese Patent Application Laid-Open No. 58-174597), a method in which the voltage applied to the electrode plate is made variable and the voltage value is adjusted for each vehicle type (Japanese Patent Application No. 58-51640 / Japanese Patent Application Laid-Open No. 59-177398). Divide the power supply rails into multiple parts or arrange a plurality of power supply rails of different lengths side by side so that they can be energized independently, and selectively energize each power supply rail according to the coating specifications of the vehicle model To adjust the amount of current by using
No. 87 / Japanese Utility Model Application No. 60-75468, Japanese Utility Model Application No. 63-127427 / Japanese Utility Model Application No. 2-51265), and each electrode can be energized individually. Adjusting the amount of current by changing the number
58-202948 / Japanese Patent Application Laid-Open No. 60-96795, Japanese Patent Application No. 58-202803
No./JP-A-60-96794).

Also, various other methods have been proposed (Minan Sho 58
-168023 / Japanese Utility Model Application No. 60-75466, Japanese Utility Model Application No. 58-168024 / Japanese Utility Model Application No. 60-75467, Japanese Patent Application No. 60-69084 / Japanese Patent Application Laid-Open No. 61-
No. 231199).

(Problems to be Solved by the Invention) In any of the above-described film thickness adjusting methods, the type of the article to be coated can be determined before the film is immersed in the paint tank, and the film thickness is adjusted according to the determined type. It is premised that conditions such as a current value can be set in advance, and an energization process is performed after the immersion according to the preset conditions.

Since the body of a car is a large product and one body is hung on one support structure of the conveyor, its type can be easily identified by the naked eye.
As disclosed in JP-A-63-244378 / JP-A-2-93098, the vehicle type is automatically determined beforehand by using an optical sensor or the like, and the coating conditions are set. A coating method of forming a coating film is employed.

However, it is often used for painting small products,
In electrodeposition coating, a method in which articles to be coated are placed on a pallet or stacked on a support structure, and immersed in a paint tank while being hung on a conveyor and transferred, several or several different types are usually used. Because several tens of articles to be painted are loaded on a single pallet, etc., even if an optical sensor is used instead of the naked eye, before entering the tank, all types of articles to be painted are determined in advance and the number is determined. It is difficult to calculate.

Therefore, in such electrodeposition coating, none of the above-mentioned film thickness adjusting methods can be adopted, and therefore, development of a new film thickness adjusting means has been required.

The present invention has been made to meet this demand, and its purpose is to simultaneously and continuously deposit a plurality of products of different types, regardless of the type and number of the products, and always perform electrodeposition. An object of the present invention is to provide an electrodeposition coating apparatus capable of forming a coating film to an appropriate and uniform thickness.

(Means for Solving the Problems) In the course of research and development, the inventor of the present invention immersed the article to be coated in the electrodeposition coating tank and then increased the voltage applied to the electrode plate in the coating tank. And the fact that the time-dependent increase in the integrated current value or the current increase rate between the electrode plate and the electrode plate is almost proportional to the total surface area of a set of articles to be coated loaded on a pallet or the like, and completed the present invention. .

That is, the electrodeposition coating apparatus according to the present invention, the article to be coated is loaded on a support structure such as a pallet, and is transferred while immersed in an electrodeposition coating tank while being hung on a conveyor.
In an electrodeposition coating apparatus for forming an electrodeposition coating film by energization, the current between the article to be coated and the electrode plate is integrated during a period in which the voltage applied to the electrode plate in the coating tank is increased after the immersion of the article to be coated. A monitor means for measuring and monitoring the value or rate of increase, and coating conditions such as voltage applied to the electrode plate and energizing time based on the measured integrated current value or current change over time. The present invention is characterized in that a control device is provided for determining each set of articles to be coated and performing electrodeposition coating in accordance with the coating conditions determined for each of the sets of articles to be coated.

(Summary of the Invention) The electrodeposition coating apparatus of the present invention is provided with means for measuring and monitoring the integrated value or increase rate of the current between the article to be coated and the electrode plate in the paint tank. Such a monitoring means is provided with a shunt circuit, for example, in an electric wiring connecting an energizing DC power supply and an electrode plate in a paint tank, preferably an electrode plate in an entry area, and measures an integrated current value or a current increase rate by an ammeter. A readable configuration is sufficient. The monitoring of the integrated current value or the current increase rate may be performed at least during a period in which the voltage applied to the electrode plate in the paint tank after dipping the article to be coated is increased.

Further, the electrodeposition coating apparatus of the present invention, based on the integrated current value measured by the above means or the amount of change in the current increase rate over time, the coating conditions, for each set of workpieces suspended on the conveyor And a control device for performing electrodeposition coating in accordance with the conditions determined for each set.

This control device is composed of, for example, an analog / digital converter and a digital arithmetic unit. As a typical example, first, when the type and the number of articles to be coated are known, preferably at the time of maximum loading, The temporal change of the integrated current value or the current increase rate is measured and recorded in advance as a reference value, and the actually measured integral current value or the current change rate of the current increase rate is compared with the reference value. Then, the total surface area of a set of articles to be coated on a pallet, etc., and if possible, the type and number of them are determined, and then the coating conditions such as the voltage applied to the electrode plate and the energizing time are determined. The control means may be determined each time, and the energization may be adjusted according to the determined conditions.

(Operation) In the present invention, the integrated current value or the current increase rate between the article to be coated and the electrode plate during a specific period is measured and monitored by the monitor means, and the integrated current value or the current measured by the control device is measured. Various coating conditions are determined for each set of articles to be coated based on the change over time of the increasing rate, and the electrodeposition coating is performed according to the determined conditions.

Therefore, even if the type and number of objects to be coated hung on the conveyor are different for each set, the coating conditions are determined so as to form an appropriate and uniform coating film, and the electrodeposition coating is performed according to such conditions. A film can be formed.

(Example) Hereinafter, an example of the present invention will be described with reference to the drawings.

Although the embodiment relates to a slipper-dip type electrodeposition coating apparatus as shown in FIG. 1, it goes without saying that the present invention is also applicable to a batch type electrodeposition coating apparatus.

In the figure, 1 indicates an electrodeposition coating tank, 2 indicates a cationic electrodeposition coating therein, 3a and 3b indicate electrode plates laid on the bottom of the coating tank 1, and 4a and 4b indicate 2 shows a power supply rail arranged near the upper part of the paint tank 1. And 5a, 5b
3 shows a DC power supply electrically connected to an electrode plate and a power supply rail.

On the other hand, 6 indicates a conveyor mounted on the upper side of the electrodeposition paint tank 1, and 7 indicates a pallet suspended in parallel with the conveyor. The conveyor 6 immerses the articles A loaded on the pallet 7 continuously in the paint tank 1 by a mechanism (not shown), and transports the articles A (in the direction of arrow F).

During this transfer, the current collector 8 comes into contact with the power supply rails 4a and 4b, so that the article A in the paint tank and the electrode plates 3a and 3b are electrically connected to each other, and the power is supplied from the power supplies 5a and 5b. A coating film is formed on the surface of the article A to be coated.

The above configuration is similar to that of a general electrodeposition coating apparatus.

In the apparatus of the embodiment, the power supply 5a and the electrode plate 3a
Alternatively, the monitor means 10 and the control device 11 as shown in FIG. 2 are connected to the electric wiring 9 connecting the power supply rail 4a.

As shown in FIG. 2, the monitor means 10 is configured by providing a shunt circuit in the wiring 9, and at least during a period in which the voltage applied to the electrode plate 3a in the paint tank is increased after the article A to be coated is immersed. The integrated value of the current (voltage 0 to 60 mV) flowing through the wiring 9 is measured by the ammeter 12 and monitored.

Further, the control device 11 is connected in order from the ammeter 12,
It comprises an analog / digital converter 13, a digital operation unit 14, and a variable resistor 15. The converter 13 converts the DC current measured by the ammeter 12 into a digital signal, and sends the signal current (4 to 20 mA) to the calculator 14.

The arithmetic unit 14 is a composite arithmetic unit equipped with a microprocessor, and the integrated current value changes with time when the maximum number of articles to be coated A .. are loaded on one pallet 7 (curve in FIG. 3). a) is recorded in advance as a reference value, and a time-dependent change of an actually measured integrated current value (for example, a curve p in FIG. 3) is compared with the reference value to determine whether the integrated current value has been loaded on the pallet 7. The total surface area of the set of coated articles A, if possible, the type and number thereof are determined, and then the coating conditions such as the voltage applied to the electrode plates 3a and 3b and the energizing time are determined for each set of coated articles A, Then, a signal is sent to a control panel (not shown) of the entire apparatus to adjust the energization according to the determined conditions.

Further, the variable resistor 15 is used for compensation, and
To stabilize the control.

Thus, using the apparatus of the embodiment, for example, the coating condition at the time of maximum loading is set to 250 to 300 V, energization is performed for 3 minutes, and the voltage applied to the electrode plate 3a after the immersion of the article A is increased. Was set to 30 seconds, and the electrodeposition coating was performed. As a result, the electrodeposition coating film could always be formed in an appropriate and uniform thickness regardless of the type and number of the articles A to be coated.

A curve p shown in FIG. 3 represents a change over time of the integrated current value measured by the monitor means 10 in such electrodeposition coating.

In the figure, 1 represents the start time of the electrodeposition coating process according to the coating conditions determined by the control device 11 during the period of increasing the voltage applied to the electrode plate 3a.

Therefore, in the normal case where the number of articles A to be coated is smaller than the maximum, the voltage applied to the electrode plate is reduced after the time point l, and the energizing time is adjusted. This fact is clearly shown from the curve p in FIG.

In the present embodiment, means for monitoring the integrated value of the current flowing during the rising period of the applied voltage, and the coating conditions are determined for each group based on the change over time of the integrated current value, and the electrodeposition coating is performed according to the determined conditions. Although the electrodeposition coating apparatus equipped with the control device has been described, in place of those means and the device,
Means for monitoring the rate of increase of the current flowing during the rising period of the applied voltage, and a control device for determining the coating conditions for each group based on the change over time of the rate of current increase, and performing electrodeposition coating according to the set. Needless to say, a configuration may be used.

(Effects of the Invention) As described above, according to the present invention, when a plurality of products of different types are simultaneously and continuously electrodeposited,
Even if the type and number of products are different for each set,
Accordingly, the effect that the electrodeposition coating film can always be formed to an appropriate and uniform thickness can be obtained.

[Brief description of the drawings]

1 is a schematic view showing an electrodeposition coating apparatus according to an embodiment of the present invention, FIG. 2 is a schematic view showing a coating film adjusting means of the apparatus shown in FIG. 1, and FIG. 3 is an integration between an article to be coated and an electrode plate. 4 is a graph showing a change over time in a current value. In the figure, 1 ... electrodeposition paint tank 2 ... electrodeposition paint 3a, 3b ... electrode plates 4a, 4b ... power supply rails 5a, 5b ... DC power supply 6 ... conveyor 7 ... pallet 8 ... collector 10 monitoring means 11 control device 13 analog / digital converter 14 digital computing unit a time variation curve of reference integrated current value b time variation curve of measured integrated current value l: At the start of the coating process according to the determined conditions

Claims (1)

(57) [Claims] An article to be coated is loaded on a support structure such as a pallet, immersed in an electrodeposition paint tank while being suspended on a conveyor, and transferred, and an electrodeposition film for forming an electrodeposition coating film by energization. In the coating apparatus, during the period in which the voltage applied to the electrode plate in the paint tank is increased after the immersion of the article to be coated, the integrated value or the rate of increase of the current between the article to be coated and the electrode plate is measured and monitored. Based on the monitoring means and the measured integrated current value or the rate of increase of the current over time, the coating conditions such as the voltage applied to the electrode plate and the energizing time are determined for each suspended set of coated articles, An electrodeposition coating apparatus comprising a control device for performing electrodeposition coating in accordance with the coating conditions determined for each of the sets of articles to be coated.