JPH0293098A - Electrodeposition coating equipment - Google Patents

Abstract

PURPOSE:To easily enable accurate energizing control by turning on the necessary electrodes selected from among a plurality of electrodes provided to an electrodeposition coating equipment via the thyristors according to the coating conditions of material to be coated. CONSTITUTION:Material 11 to be coated is transferred via a hanger 2 of a conveyor 1 and immersed in an electrodeposition tank 4. Electrodeposition coating is performed in electrodeposition coating therein by performing energizing between the material 11 connected with a current collecting rail 3 and electrodes 6a, 6b, 7a-7e. In the electrodeposition coating equipment, a plurality of electrodes 7a-7e provided side by side along the carrier passage of the material 11 are parallel connected with a power source device 5 via the thyristors 8 actuated respectively as a switching element of large electric power. Necessary current value and number of the electrode are set by an energizing controller 9 equipped with both a limit switch 10 sensing transportation of the material 11 and an optical sensor 12 according to the coating conditions of the successively transported material 11. Necessary electrodes 7a-7e are selected in correspondence with the number of the electrode and the control signals for turning on the necessary electrodes are output to the respective thyristors 8.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention involves forming an electrodeposited coating film by applying electricity to an object to be coated that is placed on a container hanger and immersed in an electrodeposition coating solution. This invention relates to an electrodeposition coating device.

[Conventional technology]

When electrocoating an automobile body by immersing it in an electrocoating paint solution in an electrocoating bath, place a diaphragm electrode that serves as a positive electrode along the electrocoating bath, and place it on a container hanger to perform electrocoating. The car body placed in the tank is connected to a current collector rail serving as a negative electrode via a hanger, and an electrodeposited coating film is formed on the surface of the car body.

A normal current collector rail is divided into a low-voltage rail section and a high-voltage rail section, and when an automobile body is placed in a tank, this is connected to the low-voltage rail section to prevent steps and rough skin from the electrodeposition coating. After it is completely immersed in the tank, it is connected to the high voltage rail section to increase the throwing power of the electrodeposition paint.

By the way, in car painting, the thickness of the electrodeposited film is 2
Strict control is required within the range of 0 μm to 30 μm (±15%), but the size of the car body immersed in the electrodeposition paint solution in the electrodeposition tank differs depending on the car model, and the coating is difficult to control. If the areas are uneven, there is a problem that accurate control of the film thickness becomes impossible.

In other words, since car bodies of different sizes, such as large cars and small cars, are transferred to the car painting line in a mixed manner, if the current is applied to match the film thickness of a large car with a large coating area, the paint film of a small car with a small surface area will be 11. If it becomes too much, you will end up wasting paint.

Furthermore, the coating film on the car body differs in +7 between luxury cars and ordinary cars, but if these are mixed and transferred, the film thickness cannot be changed for each car type.

[Problem to be solved by the invention]

For this reason, in the past, a bypass rail was installed on the main conveyor rail that transports the car body in the electrodeposition bath, and the main conveyor rail branched out from the middle and intersected with the rail again. A hanger carrying a large vehicle with a large surface area is removed from the electrocoating tank while suspended on the main conveyor rail, while a hanger carrying a general vehicle that may require a thin coating film or a small vehicle with a small coating area is suspended from the main conveyor rail. There are some vehicles that switch to the bypass rail midway to make the vehicle exit the tank earlier than luxury or large vehicles, thereby shortening the energization time (Japanese Patent Laid-Open Publication No. 125394/1983), but in this case, it is unnecessary Providing a bypass rail increases the equipment cost for the conveyor, and there is a risk that a hanger carrying a general vehicle or small vehicle may fall off when changing between the two rails, causing the painting line to stop.

In addition, attempts have been made to change the effective area of each electrode depending on the vehicle model by installing a shielding material on the front side of each electrode arranged in parallel inside the electrodeposition tank to change the exposed area. (Refer to Publication No. 60-75466), in this case, shielding +
A driving mechanism and the like are required, which increases the equipment cost of the entire device, and at the same time, there are problems in that it is prone to breakdowns and lacks reliability.

Note that a method has also been proposed in which the effective area of each electrode is changed by dividing each electrode into two and applying current from both sides at the same time for large cars, and from only one for small cars. (Refer to Japanese Patent Application Laid-Open No. 61-231199), this had the problem that the energization state could only be switched between two stages, and only the one that was constantly used was damaged quickly.

In addition, attempts have been made to change the voltage by moving the electrodes arranged in parallel in the electrodeposition tank back and forth with respect to the object to be coated, which serve as opposite electrodes, and changing the distance between the electrodes (in practice). (Refer to Publication No. 60-75467), in this case, a drive mechanism is required to move each electrode forward and backward, which increases equipment costs, and at the same time, strict film thickness control is required because changes in voltage and film thickness are not exactly proportional. The problem was that it was not possible.

Therefore, the technical object of the present invention is to enable accurate energization control according to the coating conditions of the object to be coated with a simple configuration that does not increase equipment costs.

[Means to solve the problem]

In order to solve this problem, the present invention provides a plurality of electrical currents to be applied to the object to be coated along an electrodeposition tank in which the object to be coated, which is transferred on a hanger of a conveyor, is immersed in an electrodeposition paint liquid. In an electrodeposition coating apparatus in which electrodes are arranged in parallel, each electrode is connected in parallel to a power supply device through a thyristor serving as a high-power switching element, and the objects to be coated are sequentially placed in an electrodeposition bath. Set the current value according to the painting conditions of
An energization controller is provided that selects a necessary number of electrodes from among the electrodes to satisfy the set value and outputs a control signal to turn on a thyristor that supplies power to the selected electrodes. It is characterized by the presence of

[Effect]

According to the present invention, the energization controller sets the current value according to the coating conditions of the object to be coated, which is placed on the hanger of the container and placed in the electrodeposition bath, and is necessary to satisfy the set value. At the same time, a control signal is output to turn on the thyristor that supplies power to each selected electrode from the power supply device. do.

As a result, power is supplied only to the electrodes selected by the energization controller, and the amount of current applied to the object to be painted is set to a size that corresponds to the painting conditions of the object to be painted, so it is accurately proportional to the amount of current. The thickness of the electrodeposited coating can be precisely controlled depending on the type and size of the object to be coated.

〔Example〕

Embodiments of the present invention will be specifically described below based on the drawings.

The figure is a flow sheet diagram showing an example of an electrodeposition coating apparatus according to the present invention.

In this example, hanger (2) of con hair (1), (2)-
A current collector rail (3) that slides into contact with the low voltage rail part (3a) is arranged from the entrance side of the electrodeposition tank (4) to the center of the tank.
and a high voltage rail section (3h) arranged from the center of the tank to the outlet side, and these low voltage rail sections (3a)
and a high voltage rail section (3b) are connected in parallel to the negative electrode side of the power supply device (5).

On the positive electrode side of the power supply device (5), there are a plurality of electrodes (6a), (6b), (7) arranged in parallel along the inside of the electrodeposition bath (4).
a) to (7e) are connected in parallel.

Among these, electrodes (7a) to (7e) are arranged in parallel along directly below the high voltage rail part (3b), and a power supply device (5) supplies a current of 100A to 20OA to each electrode. A thyristor (8) serving as a high power switching element is interposed in each of the connected circuits.

Each thyristor (8) has a capacitance of several hundred amperes, and even if it becomes conductive, it can be turned off again by a gate signal.
GTO thyristor) is used.

An energization controller (9) that turns on/off each of these thyristors (8) is connected to a conhair synchronization signal that is output according to the transfer speed of the conhair (1), and a conhair synchronization signal that is outputted in accordance with the transfer speed of the conhair (1).
The switch signal of the limit switch Oω that detects the presence of the hanger (2) transferred to the input tank side, and the presence or absence of the object to be coated (11) placed on the hanger (2) when the switch signal is output. Based on the detection signal of the optical sensor 02) that determines the size, a control signal is sent at a predetermined timing to cause positive and negative gate currents to flow from the gate circuit 03) between the gate and cathode of each thyristor (8). It is designed to be output as .

In other words, when the energization controller (9) receives a switch signal from the limit switch θ0), the conveyor is the same!
At the same time, each hanger (2) starts counting the IJI signal and calculates the time during which each hanger (2) is in sliding contact with the high voltage rail part (3b), based on the detection signal input from the optical sensor Q2). The presence or absence and size of the object to be painted (11) placed on the river are determined, and the object to be painted determined based on its size (according to the painted area of the river, the current should be applied when passing through the high voltage rail part (3b)). Set the current value.

Then, select the necessary number of electrodes from among electrodes (7a) to (7e) to satisfy the set value, and
When the bunker (2) carrying 1) comes into sliding contact with the high voltage rail part (3h), the thyristor (8) is turned to the gate circuit 03) of the thyristor (8) that supplies DC power to the selected electrode.・Outputs a voltage signal that is a control signal to turn on.

The gate circuit 03) to which the voltage signal is input from the energization controller (9) outputs a positive gate trigger current to turn on the thyristor (8).

As a result, DC power is supplied only to the electrode selected by the energization controller (6) from among the electrodes (7a) to (7e), and the object to be painted (1
1) The electric current applied to /J! The amount of i is set to the optimum size according to the coating area, and the thickness of the electrodeposition coating film formed on the surface of the object to be coated (11) is strictly controlled.

When the object to be coated (11) passes the high voltage rail part (3b) after a certain period of time, the energization controller (9)
stops outputting the voltage signal.

This eliminates the input voltage entering the gate circuit 03), causing the gate circuit 03) to output a negative gate trigger current, turning off the thyristor (8).

Note that in order to turn off a thyristor once turned on, there are methods such as reducing the current flowing through the element to be less than the holding current, or applying a reverse voltage between the anode and cathode using a forced commutation circuit.

〔Effect of the invention〕

As described above, according to the present invention, it is possible to control the amount of current applied according to the coating conditions of the object to be coated immersed in the electrodeposition paint liquid with a simple configuration that does not increase equipment costs. It has very good effects.

[Brief explanation of the drawing]

The figure is a flow sheet diagram showing an example of an electrodeposition coating apparatus according to the present invention. Explanation of symbols (1) - conveyor, (2) - hanger, (3) - current collection rail, (4) - electrodeposition tank, (5) - power supply device, (7a) - (
7e) - Electrode, (8) - Thyristor, (9) - Current controller, (11) - Object to be painted. Procedural amendment motion December 22, 1988 Director General of the Patent Office Yoshi 1) Moon Takeshi 1, Indication of the case 1988 Patent Application No. 244378 2, Name of the invention Electrodeposition coating device 3, Person making the amendment Case Relationship with Patent Applicant Address: 2-4-1 Marunouchi, Chiyoda-ku, Tokyo Name: Trinity Kogyo Co., Ltd. 4 Agent Address: 151 December 20, 1988 (Delivery mortar) 6. ? di Positive Object (Separate 81F,) 1. The statement in the "Detailed Description of the Invention" is corrected as follows. On page 7, line 10 of the specification, the statement ``The figure is'' is corrected to ``Figure 1 is''. 2. The description in "Brief explanation of the drawings" is corrected as follows. On page 11, line 7 of the specification, the statement ``The figure is'' is corrected to ``Figure 1 is''.

Claims (1)

[Claims] Electricity is applied to the object to be coated (11) along the electrodeposition tank (4) in which the object to be coated (11), which is transferred on the hanger (2) of the conveyor (1), is immersed in the electrodeposition paint. Multiple electrodes (
In the electrodeposition coating device in which 7a) to (7e) are installed in parallel,
Each of the electrodes (7a) to (7e) is connected to a power supply device (5) via a thyristor (8) serving as a high-power switching element.
The current value is set according to the coating conditions of the objects to be coated (11) which are connected in parallel to the electrodeposition tank (4) and sequentially entered into the electrodeposition tank (4), and the necessary number of electrodes to satisfy the set value is set. an energization controller that selects one of the electrodes (7a) to (7e) from among the electrodes (7a) to (7e) and outputs a control signal to turn on the thyristor (8) that supplies power to the selected electrode;
9) An electrodeposition coating device comprising: