JPH0222496A - Multistage current supply-type electrodeposition coating device - Google Patents

Abstract

PURPOSE:To apply an optimum electrodeposition current irrespective of the kinds of works and to stably obtain a high-quality electrodeposition coating by previously discriminating the kind of the work, and optimizing the currents to be supplied to plural electrodeposition electrodes in the electrodeposition cells based on the discrimination signal at the time of electrodeposition-coating the works of complicated shapes with multistage current supply. CONSTITUTION:A work W such as an automobile body is dipped in an electrodeposition soln. P in the electrodeposition bath 1 having a boat-shaped cross section through a rail 11 also used as a feeder line. The kind of the work W is discriminated by a work discriminating device 12 at the inlet to the bath 1, the discrimination signal is inputted to a sequence controller 13, and an optimum electrodeposition condition for the work W is read out from the electrodeposition condition stored therein. The current controllers 7-10 for the electrodeposition electrodes 3-6 are adjusted so that an initial current appropriate for the work W is applied to the electrodes 3-6 as the work W dips into the electro-deposition bath, and a high-quality electrodeposition coating is obtained.

Description

[Detailed Description of the Invention] (Field of Industrial Application) Is the present invention suitable for painting many types of workpieces? Regarding the wearing equipment.

(Prior art) When painting large workpieces with complex shapes such as automobile bodies, a plurality of electrodes are placed in an electrodeposition tank a with a boat-shaped cross section in the direction of movement of the workpiece b, as shown in Figure 3. cSd
Se is installed, and the workpiece b is transferred to the electrodeposition tank a by the conveyor rail f.
Electrodeposition is performed by applying voltage E between electrodes c, d, and e and workpiece b while moving the workpiece inside. Note that the symbol g in the figure indicates a power supply device that supplies the electrodeposited TIE flow.

However, as a general phenomenon in electrodeposition coating, when the workpiece is first immersed, a rapid electrodeposition current q flows because no film has been formed on the workpiece surface (Figure 4), and film formation progresses rapidly. In the case of a workpiece made by joining a plurality of members, such as an automobile body, there is a problem in that film formation becomes insufficient at parts with intricate shapes such as the joining parts.

In other words, if the object to be painted has an uneven shape, the distance between the electrode and the surface to be painted will vary greatly, especially! There is a problem in that the film thickness is thinner in parts located far from the poles.

In order to solve this problem, a plurality of electrodeposited electrodes arranged 9+1 in the direction of movement are divided into groups, and the applied voltage is set higher for the electrodes closer to the direction of movement. It has also been proposed to prevent the generation of excessive current (Utility Model Application Publication No. 56-7761), but since a potential difference is always set on the electrode surface, the low potential side, that is, the entry point. Current flows into the electrodeposited electrode on the side from the high potential side, that is, the electrode on the discharge port side, and a film is formed on the electrode surface. There is a problem that it loses its function as a pole.

(Problems to be Solved) The present invention has been made in view of these problems, and is a multi-stage electrodeposition method that can supply an electrodeposition current under optimal conditions regardless of the type of workpiece. Our objective is to provide coating equipment.

(Means for Solving the Problems) In order to solve such problems, in the present invention, a plurality of t-shirts arranged in a row along the movement path of the workpiece!
The electrodes are divided into multiple groups in the moving direction of the workpiece, and the electrodeposition electrodes of each group are connected to the electrodeposition current adjusting device through diodes that are in the forward direction with respect to the workpiece. I of the workpiece in front of the moving route. The electrodeposition current adjusting device is controlled based on the signal from the determination means by a control means that has preset the optimum energization conditions for each type of workpiece. f! The method automatically selects the optimal electrodeposition current corresponding to the type of electrodeposition to form a gentle initial film and improve the film growth rate during the film growth process, while preventing current from flowing between the electrodes using a diode. It is in.

(Example) The present invention will now be described in detail based on illustrated examples.

FIG. 1 shows an embodiment of the present invention, in which reference numeral 1 denotes an electrodeposition tank with a boat-shaped cross section and an overflow tank 2.2 located outside. A plurality of electrodeposited electrodes 3, 4, 5, 6 are arranged in a row, and a capacitor liquid p is housed inside, and each of the electrodeposited electrodes 3 to 6 is arranged in a forward direction toward the object to be coated. diode 20.2 so that
1.22.23 via T flow regulator a7.8.9.10
It is connected to the.

At the top of the storage tank 1, a conveyor rail 11 which also serves as a power supply line is arranged so as to follow the shape of the bottom plate of the electrodeposition tank 1. 1
2 is a workpiece determination device placed in front of the electrodeposition tank 1;
For example, it consists of a shape recognition device such as an imaging device, a magnetic detection device, etc., and f! It is configured to determine the neck and output a workpiece discrimination signal.

Reference numeral 13 is a sequence gIF device that stores the optimal electrodeposition conditions determined in advance through experiments for each type of workpiece as data, selects one piece of data based on a workpiece discrimination signal, and moves the workpiece. Read the current value according to this? The current adjustment device 7 according to the current value
to 1o.

Next, the operation of the H position configured as described above will be explained based on the waveform diagram shown in FIG.

When the apparatus is operated, the workpiece W is transported by the transport rail 11 toward the electrodeposition tank 1, and passes through the workpiece determination device t12 on the way. The workpiece determination device 12 determines the type of workpiece that has passed and outputs a determination signal. The sequence control device 13 reads out the optimal electrodeposition conditions for the workpiece W that has just passed from among the stored electrodeposition conditions based on the discrimination signal. In this manner, when the workpiece W starts entering the tank, the sequence control device 13 adjusts the current control devices t7 to 1O so as to generate a paddy amount current suitable for the workpiece.

As a result, electrodeposition is started without causing a sudden increase in electrodeposition current, and a film is formed gently.

On the other hand, the sequence control device 12 gradually increases the output voltage of each current adjustment device as the workpiece W moves. As a result, the optimal electrodeposition current value is maintained over a long period of time, and electrodeposition can be carried out without decreasing the film growth rate, despite the increase in electrical resistance due to the increase in film thickness on the surface of the object to be coated. That will happen.

By the way, in the process of adjusting the flow of electrodeposition, potential differences ΔE, ΔE', and ΔFIT will occur between each electrode, but the diodes 20-23 connected to each electrode act in opposite directions between the electrodes. Therefore, on the high potential side! Current flow from the pole to the electrode on the low potential side will be blocked.

When an electrodeposited film of a predetermined thickness is formed, the workpiece W is pulled up from the electrodeposition tank 1, and then different types of workpieces are placed in the electrodeposition tank 1.
When the workpiece is transported to 11, the workpiece determining means 12 determines the type of the workpiece and outputs a determination signal. The sequence control circuit 13 receives this discrimination signal, selects electrodeposition conditions suitable for performing electrodeposition coating on the workpiece, and thereafter controls the flow of electricity according to the movement of the workpiece by the same process as described above.
Arrange.

In this example, the electrodeposition current is controlled based on the time from the reference time, but a plurality of detectors are arranged in the direction of the conveyance path, and control is performed based on future signals. It is clear that the same effect can be achieved.

Furthermore, in the above embodiment, in order to simplify the explanation, one current adjustment device is connected to each T4 electrode, but a plurality of electrodes are treated as one group, and each group has a current of v4! ! It is clear that the same effect can be achieved even if the devices are connected.

Further, in this embodiment, the type of workpiece is determined based on the shape and dimensions of the workpiece, but it is clear that the same effect can be achieved by using an identification label such as a bar code.

(Effects of the Invention) As explained above, in the present invention, a plurality of electrodeposited electrodes arranged in a row along the movement path of the workpiece are divided into a plurality of groups in the movement direction of the workpiece, and each group is Adjust the electrodeposition flow for the t11 pole! In addition to connecting the device, a workpiece determination means for determining the type of workpiece is arranged in front of the electrodeposition tank on the workpiece movement path of the electrodeposition tank, and the control means preset the optimum energization conditions for each type of workpiece. Since the electrodeposition current adjusting device is controlled based on the signal from the determination means, it is possible to automatically supply the optimum electrodeposition current regardless of the type of workpiece. It is not possible to perform high-quality electric @ painting even on surfaces. In addition, since the electrodeposition electrode and the electrodeposition current adjustment device were connected through a diode with the forward direction facing the object to be coated, +! !
Interelectrode current can be blocked regardless of the potential difference generated between the electrodes, and film formation on the t11 electrode can be prevented, thereby simplifying device maintenance work.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram of an apparatus showing one embodiment of the present invention, and FIG.
3 is a waveform diagram showing the operation of the same apparatus, and FIG. 3.4 is a configuration diagram and a waveform diagram showing an example of a conventional electrodeposition apparatus, respectively. l...Electrodeposition baths 3-6...Electrodeposition electrodes 7-10...71 Deposition current adjustment device 11...Transportation rail 12...Workpiece determination device 13...Sequence control device 20 ~23...Diode Fig. 1 2θ-+23 Fig. 2 Irita 1 exists. Tokihara

Claims (1)

[Claims] A plurality of electrodeposited electrodes arranged in a row along the moving path of the workpiece are divided into groups in the direction of movement of the workpiece, and each group of electrodeposited electrodes is connected through a diode with the side to be coated facing forward. In addition to connecting to the electrodeposition current adjustment device, a workpiece determination means for determining the type of workpiece is installed in front of the electrodeposition tank on the workpiece movement path of the electrodeposition tank, and the optimal energization conditions are set in advance for each type of workpiece. A multi-stage electrification electrodeposition coating apparatus, wherein the control means controls the electrodeposition current adjusting device based on the signal from the determination means.