JPH0523576Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an electrodeposition tank equipped with a stirring device for a coating liquid in the tank.

[Prior art] Electrodeposition coating equipment that forms a coating film on the surface of a workpiece immersed in a paint solution in an electrodeposition tank is equipped with a coating system that uses paint inside the tank to prevent precipitation of paint components and to make the paint solution uniform within the tank. A liquid stirring device for forcibly stirring the liquid is provided.

Such a liquid stirring device generally has a structure shown in FIG. 3, for example, as disclosed in Japanese Unexamined Patent Publication No. 62-192598.

In FIG. 3, 1 is an electrodeposition tank, 2 and 2 are overflow tanks, and the coating liquid in this overflow tank 2 is pressurized by a pump (not shown).
It is circulated by a liquid circulation device consisting of a riser pipe 3, an injection nozzle 4, etc. Further, the liquid is stirred by a pair of left and right liquid stirring devices 10, 10, and is circulated as a whole in the tank 2.

Here, the liquid stirring device 10 is formed from a stirring blade 12 arranged in a draft tube 11 and a motor 14 connected to the stirring blade 12 by a rotating shaft 13. The draft tube 11 is provided to efficiently circulate the coating liquid within the tank 1 using stirring power. Therefore, the draft tube 11 is provided with an upper opening 11U and a lower opening 11D through which the paint liquid in the tank 1 flows in and out.

Further, the draft tube 11 is covered using the horizontal portion 15F of the holding casing 15 of the motor 14 in order to prevent dust from entering from the outside. The rotating shaft 13 passes through the hole 15H in the horizontal portion 15F.

On the other hand, in order to form a uniform and high-quality coating film, it is necessary not only to stir and circulate the liquid by stirring the liquid as described above, but also to introduce air bubbles brought in when the workpiece is put into the paint liquid in tank 1, and air bubbles generated by electrolysis. Foam based on etc. must be removed. Since this foam floats on the surface of the paint liquid, it is removed by overflowing into the overflow tank 2.

[Problem to be solved by the invention] By the way, in the conventional electrodeposition tank 1, the ability to circulate and stir the paint liquid can be adjusted as appropriate by, for example, increasing the rotational speed of the motor 14. However, no measures have been taken to prevent froth formation. This is because the phenomena of generation and introduction of gas vesicles and their quantitative nature are uncertain, and because the paint liquid is opaque, they cannot be visually confirmed. This is because the amount of air cells brought in at the time of charging was a compromise that was inevitable due to the work shape.

Therefore, since the amount of foam generated is a natural premise, the removal of foam can be solved by expanding the shape of the overflow tank 2, specifically, by expanding the overflow path from tank 1 to overflow tank 2 in plan. It was supposed to be done.

If the amount of foam generated can be reduced, the quality of the coating film can be further improved, and the overflow tank 2 (more specifically, the form of the overflow passage to the overflow tank 2, etc.) can be made smaller and simpler, and the pump can be improved by reducing the amount of overflow.・It should be possible to simplify the conduit, reduce power consumption, and increase the freedom of layout.

The present invention was devised in view of the above circumstances, and its purpose is to provide an electrodeposition bath that can achieve high-quality coating and simplify equipment by eliminating unavoidable causes of bubbles from the viewpoint of device structure. There is a particular thing.

[Means for Solving the Problems] The present invention solves the problem of the amount and manner of foam generation when, for example, the motor rotation speed is increased to enhance liquid stirring, the rotation direction is changed, or the operation mode is changed. We focused on the subtle changes in the air and based on the analysis and research conducted through numerous actual machine operation results, we established that the inside of the draft tube and the atmosphere may be mixed in, based on the fact that the air may be mixed in with the eddy flow that accompanies liquid stirring. It is designed to be airtightly isolated.

That is, an electrodeposition tank equipped with a liquid stirring device consisting of a stirring blade disposed in a draft tube having upper and lower openings through which the paint liquid in the tank flows in and out, and a motor connected to the stirring blade by a rotating shaft. The rotary shaft is hermetically sealed to airtightly isolate a space inside the draft tube from the atmosphere on the side where the motor is disposed.

[Operation] According to the present invention having the above configuration, even when the liquid stirring device is operated, the draft tube interior space and the atmosphere on the motor installation side are hermetically isolated by airtightly sealing the rotating shaft. Therefore, since the supply path for atmospheric air mixed into the paint liquid in the draft tube due to the rotational action of the rotating shaft is cut off, it is possible to prevent froth from forming due to air bubbles mixed into the paint liquid.

Therefore, it is possible to avoid the occurrence of spots due to the adhesion of bubbles and achieve high quality coating. Moreover, since unnecessary bubbles are removed, equipment such as overflow tanks can be simplified and operating costs can be reduced.

[Example] Hereinafter, an example of the present invention will be described based on the drawings.

FIG. 1 is a vertical cross-sectional view of the main parts, and FIG. 2 is a vertical cross-sectional view showing the overall configuration. However, in FIG. 2, the overflow tank 2, liquid circulation devices (3, 4, etc.), etc. are not shown. Note that 7 and 7 are electrodes.

Now, on both sides of the electrodeposition tank 1, a pair of liquid stirring devices 10, 10 are provided. Each liquid stirring device 10
The upper opening 11U is a suction port, and the lower opening 11D is
is formed to act as a discharge port.
Therefore, the liquid stirring devices 10, 10 are designed to stir the sucked paint liquid and circulate it in an upward flow within the electrodeposition tank 1 as shown in FIG.

The liquid stirring device 10 includes a draft tube 11, stirring blades 12, a rotating shaft 13, a motor 14, and the like. As shown in FIG. 1, inside the cylindrical draft tube 11, stirring blades 12 are arranged to stir the paint liquid sucked in from the upper opening 11U and forcefully feed it in the direction of the arrow. Each stirring blade is arranged in tandem on a rotating shaft 13, and a gear mechanism 16
It is connected to the motor 14 via. This motor 14 is fixed to the upper end surface 11F of the draft tube 11 with bolts (not shown) using the horizontal portion 15F of the casing 15.

Here, horizontal part 15F and draft tube 1
A gasket 17 is interposed between the upper end surface 11F of 1 and the through hole 1 provided in the horizontal portion 15F.
Seal members 18 are provided in multiple stages between 5H and the rotating shaft 13.

Therefore, the empty space 1 in the draft tube 11
1S and the atmosphere on the side where the motor 14 is disposed are airtightly isolated, and are configured to prevent not only dust from entering but also air from entering.

The coating liquid in the electrodeposition tank 1 having such a structure is stirred in both stirring devices 10, 10, and circulated as an upward flow as shown in FIG.

At this time, the empty space 11S in the draft tube 11
is isolated from the atmosphere, so even if swirling occurs in the paint liquid due to the rotation of the rotary shaft 13, the air sucked into it will be almost completely absent during normal operation because the supply route is cut off. Therefore, there is no contamination of air bubbles other than the air bubbles generated due to the inevitable electric action and the air bubbles adhering to the work during immersion, and the generation of bubbles in the tank 1 can be controlled to the minimum necessary level.

According to this embodiment, the rotary shaft 13 is hermetically sealed and the empty space 1 in the draft tube 11 is sealed.
1S and the atmosphere on the side where the motor 14 is disposed are airtightly isolated, so unnecessary air bubbles due to the operation of the liquid stirring device 10 are not mixed into the paint liquid.
The generation of bubbles caused by this can be prevented. Therefore, the amount of foam that adheres to the workpiece during immersion into the electrodeposition bath 1 is minimized, and any remaining adhered foam is removed by the rising liquid flow, making it possible to produce a high-quality coating film.

In addition, since the amount of froth generated is suppressed to the necessary minimum amount, the overflow tank 2, its circulation pump, etc. can be made smaller and simpler, and power consumption can be reduced.

In addition, due to the fluid behavior, the amount of air sucked in due to the eddy flow is large enough to achieve perfect circular operation without horizontal vibration of the rotating shaft 13, but in this invention, the amount of air sucked in is extremely small, so even more perfect circular operation is possible. This makes it possible to improve the liquid stirring effect and achieve long-term safe operation of the motor 14, bearings, etc., and also to simplify maintenance.

Furthermore, since there is no air intake due to liquid stirring,
Since air bubbles based on this do not adhere to the bottom of the workpiece immersed in the electrodeposition tank 1, high-quality coating can be achieved from this point of view as well, and the liquid after stirring rises from the bottom of the electrodeposition tank 1. Therefore, the uniformity of the paint liquid in the tank 1 can be further promoted.

[Effects of the invention] The present invention has a configuration that airtightly seals the rotating shaft of the liquid stirring device to airtightly isolate the space inside the draft tube from the atmosphere on the side where the motor is installed, so air intake due to liquid stirring is eliminated. The amount of foam generated within the electrodeposition bath can be suppressed to an inevitable minimum. Therefore, it is possible to achieve both high quality and reduced equipment and operating costs.

[Brief explanation of the drawing]

FIG. 1 is a vertical cross-sectional view of the main parts showing an embodiment of the present invention, FIG. 2 is a vertical cross-sectional view showing the overall structure, and FIG. 3 is a vertical cross-sectional view showing the overall structure of a conventional electrodeposition bath. . 1...electrodeposition tank, 2...overflow tank, 10
...Liquid stirring device, 11...Draft tube, 1
1S... Blank space, 12... Stirring blade, 13... Rotating blade, 14... Motor, 17... Packing, 18
...Seal member.

Claims (1)

[Scope of Claim for Utility Model Registration] A liquid stirring device consisting of a stirring blade disposed in a draft tube having upper and lower openings for inflowing and outflowing the paint liquid in the tank, and a motor connected to the stirring blade by a rotating shaft. An electrodeposition tank comprising the following: The rotating shaft is hermetically sealed to airtightly isolate a space inside the draft tube from the atmosphere on a side where the motor is disposed.