JPH0745568Y2 - Electro-deposition coating device - Google Patents

Description

[Detailed Description of the Invention] << Industrial Application Field >> The present invention relates to an electrodeposition coating apparatus for transferring works such as automobile bodies in series by a transfer device and sequentially feeding the workpieces into an electrodeposition tank to pass through the tank. In particular, the present invention relates to an electrodeposition coating apparatus in which an applied voltage is appropriately controlled according to a state of entering and exiting a work.

<< Prior Art >> For example, as described in Japanese Patent Publication No. 63-66919,
When the first work of the transferred work row enters the electrodeposition tank, other work does not exist in the electrodeposition tank, and when the subsequent work enters the tank, another work already exists in the tank. However, this makes a big difference in the coating conditions. When the applied voltage between the work and the in-tank electrode is constant, when the leading work enters the tank, the current locally concentrates in the entrance area, and the coating film in that area eventually becomes It is thicker than the part and the coating quality is uneven. Therefore, from the past,
When the leading work enters the tank, the applied voltage is controlled to be gradually increased from a low voltage to a specified voltage to achieve uniform coating quality.

<Problems to be solved by the invention> In the conventional apparatus, in order to determine whether or not another work exists in the electrodeposition tank immediately before a certain work enters the tank,
A detector for detecting the work just before entering the bath and a detector for detecting the work in the electrodeposition bath were provided. If there can be a maximum of 4 workpieces in the electrodeposition tank, a total of 5 workpiece detectors are required. Since this work detector uses a photoelectric or electromagnetic sensor that detects the presence or absence of a work in a non-contact manner, the equipment cost increases if a large number of sensors are required.

The present invention has been made in view of the above-mentioned conventional problems, and its purpose is to reliably detect the bathing state of the leading workpiece with equipment that is simpler and less expensive than before, and control the applied voltage to control the coating quality. An object of the present invention is to provide an electrodeposition coating apparatus capable of uniformizing the temperature.

<< Means for Solving the Problems >> An electrodeposition coating apparatus according to the present invention comprises a conveying means for conveying works in series along an electrodeposition tank and sequentially passing the inside of the tank.
Work detection means for detecting a work conveyed at a predetermined position before entering the tank, conveyance amount detection means for detecting a conveyance amount of the work by the conveyance means, and outputs of the work detection means and the conveyance amount detection means. Immediately before the received work enters the bath, the leading bath work determination means for detecting a state in which no other work exists in the electrodeposition bath, and the work when the leading bath work is detected by this determination means And a voltage control means for gradually increasing the voltage applied to the in-tank electrode from a low voltage to a specified voltage in accordance with the tank entry process of the work.

<Operation> When the carry amount detected by the carry amount detecting means reaches a predetermined value from the time when the work detecting means detects a certain work A, the work A is discharged from the electrodeposition tank. If no succeeding work is detected until the work A discharge tank, there is no work in the electrodeposition tank. The work detected after that state is the leading tank work.

<< Embodiment >> FIG. 1 shows the overall schematic construction of an electrodeposition coating apparatus according to an embodiment of the present invention. In the figure, 1 is an electrodeposition tank,
2 is a hang-conveyor-type transfer device that transfers the works A to I in series along the electrodeposition tank 1 and sequentially passes through the tank.
Is an electrode arranged in the electrodeposition tank 1, 4 is a power supply device for applying a DC voltage between the electrode 3 and the work in the tank, 5 is a power supply device 4 of the power supply device 4 depending on the state of entering and exiting the work in the tank. A controller for changing the output voltage, 6 is a work sensor for detecting a work to be carried at a predetermined position before entering the tank, and 7 is a carrying device 2
Is a rotary encoder as a conveyance amount detecting means for detecting the conveyor movement amount. In the example of the figure, the works A to I are hung on the hanger of the transfer device 2 and are transferred in series without leaving a gap, and A and B have already come out of the electrodeposition tank 1, and C, D, and E. , F are in the electrodeposition tank 1, G is the next work to enter, and H and I continue without any gap. In such a state, the power supply 4
The output voltage of is maintained at the specified value of 300 volts.

The work sensor 6 detects the work just before entering the tank,
When the work is conveyed to this position, the output signal turns on, and when there is no work at this position, the output signal turns off. The rotary encoder 7 is attached to a system that rotates with the conveyance in the conveyance device 2, and outputs a pulse signal for each minute unit conveyance amount.

The controller 5 operates based on the detection signals of the work sensor 6 and the rotary encoder 7 as shown in the flow charts of FIGS.

When the work is conveyed to a predetermined position immediately before entering the tank, the output signal of the work sensor 6 is turned on as described above, and when the work further advances and enters the electrodeposition tank 1 (installation position of the work sensor 6 The output signal is turned off.
As shown in the flowchart of FIG. 2A, when the output signal of the work sensor 6 is on, the rotary encoder 7
The carry amount counter that counts the output of is cleared (steps 101 → 102), and when the output signal of the work sensor 6 is turned off, the output of the rotary encoder 7 is counted by the carry amount counter (steps 101 → 103). That is, the counter counts the amount of conveyance after a certain work has passed the installation point of the work sensor 6. When the carry amount reaches the set value (the carry amount until the entered work is discharged), a predetermined flag F is set to "1" (step 104).
→ 105). That is, the flag F becomes "1" unless the subsequent work reaches the installation point of the work sensor 6 until the workpiece entering the tank after passing through the installation point of the work sensor 6 comes out.

Simultaneously with the above processing, the controller 5 also executes the processing of FIG. 2 (B). When a certain work reaches the installation point of the work sensor 6, the output of the work sensor 6 changes from OFF to ON. In response to this change, it is checked whether or not the flag F is "1" (step 201 → 202).
At this time, if there is a work in the electrodeposition tank 1, the flag F is "0".
If there is no work in the tank, the flag F is "1".
It has become.

If another work does not exist in the electrodeposition tank 1 when a certain work tries to enter the tank, the process proceeds to step 203, and the output voltage of the power supply device 4 is changed from the low voltage of 50 V to the specified voltage of 300 V, and the work is input. Increase gradually according to the tank process. That is, the applied voltage is 50 V at the time of starting the tank, and the voltage is gradually increased so that the applied voltage becomes 300 V when the work enters the tank completely. The output signal of the rotary encoder 7 is used for this gradual increase control, and the applied voltage is increased in proportion to the carry amount. By doing so, it is possible to always realize accurate voltage gradual increase control regardless of the transport speed of the transport device 2. In step 204 following step 203, the flag F is returned to "0".

The configuration of the present invention can also be used for controlling the last work piece to be finally discharged from the tank as follows. If another work does not exist in the electrodeposition tank 1 when a certain work is about to be taken out of the tank, local current concentration still occurs on the work, and a defect is likely to occur in the coating film. Therefore, if the present invention is applied to detect the end work and gradually reduce the applied voltage when the work is about to be discharged, the occurrence of the above defects can be prevented in advance.

<Effects of the Invention> As described in detail above, in the electrodeposition coating apparatus according to the present invention, the work detecting means for detecting the work at a predetermined position before the tank and the conveyance for detecting the conveyance amount by the work conveying means. Since the quantity detection means is provided and the leading bath work is detected based on the outputs of both of these sensing means and the applied voltage is gradually increased when the leading bath work is entered, the configuration of the leading bath work detection system is configured. However, the voltage gradually increasing control for the leading tank work can be accurately performed by the accurate detection operation, and high-quality electrodeposition coating can be performed with a simple configuration.

[Brief description of drawings]

FIG. 1 is an overall schematic configuration diagram of an electrodeposition coating apparatus according to an embodiment of the present invention, and FIG. 2 is a flow chart showing the main operation of the controller 5 in the embodiment. DESCRIPTION OF SYMBOLS 1 ... Electrodeposition tank, 2 ... Transport device 3 ... Electrode, 4 ... Power supply device 5 ... Controller 6 ... Work sensor (work detection means) 7 ... Rotary encoder (transport amount detection means) A to I ……work

Claims (1)

[Scope of utility model registration request] 1. A transfer means for transferring works in series along an electrodeposition tank to sequentially pass through the inside of the tank, a work detection means for detecting a work transferred at a predetermined position before entering the tank, and the transfer. Conveyance amount detection means for detecting the conveyance amount of the work by the means, and a state where no other work exists in the electrodeposition tank immediately before the work receiving the output of the work detection means and the conveyance amount detection means enters the tank The leading entrance tank work determining means for detecting the above, and the applied voltage between the workpiece and the in-tank electrode when the leading entrance tank work is detected by this determining means An electrodeposition coating apparatus comprising: a voltage control unit that gradually increases the voltage to a specified voltage.