JPH0114819B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention supplies a coating agent such as paint or lubricant to a cup-shaped body that is driven to rotate at high speed and to which a high voltage is applied, and atomizes the coating agent and radiates it. This invention relates to improvements in electrostatic coating equipment.

Conventionally, this type of electrostatic coating apparatus has been constructed as shown in FIG. A rotating shaft 2 projects forward and is extended, and a cup-shaped body 3 is fixed to the tip thereof.

This cup-shaped body 3 includes a substantially cylindrical outer cylinder 4, a partition wall 5 that closes the axial center of the outer cylinder 4, and a partition wall 5 that closes the central part of the outer cylinder 4 in the axial direction.
It is formed from a truncated conical inner cylinder 6 that is integrally molded in the center and whose diameter gradually increases as it goes toward the partition wall 5, and a required interval is provided between the partition wall 5 and the outer cylinder 4. While the slit 7 is formed, a high voltage of about 80 to 120 KV is applied, although not shown.

Reference numeral 8 denotes a coating agent supply pipe for supplying a coating agent such as paint or antirust oil to the back surface of the partition wall 5 of the cup-shaped body 3, and is connected to a coating agent passage 9 formed inside the front end side of the case body 1. They are screwed together. and,
This coating agent passage 9 opens on the side surface of the case body 1,
It is connected via a nipple 10 and a hose 11 to a coating agent supply source (not shown).

The above is an example of the configuration of the conventional device shown in FIG. When a coating agent is supplied to the back surface of the partition wall 5 through the coating agent supply pipe 8 in this state, the coating agent is transferred from the back surface of the partition wall 5 through the slit 7 to the inner circumferential surface of the outer cylinder 4 due to centrifugal force, and then It is supplied in the form of a thin film to the front end surface of the outer cylinder 4 along its inner peripheral surface.

Here, since a high voltage of about 80 to 120 KV is applied to the cup-shaped body 3, the coating agent supplied in the form of a thin film to the front end surface of the outer cylinder 4 is atomized and transported at a required speed, for example. The light is radiated onto the object 12 to be coated, such as a plate-shaped body, and electrostatically coated on the object 12 to be coated.

However, in such a conventional electrostatic coating device, the work of applying the coating agent to the object 12 to be coated,
Particularly, the work of electrostatically applying rust preventive oil to steel strips, etc. is carried out in a sealed oil application chamber, and since the cup-shaped body 3 is driven to rotate at high speed, the object to be coated (in this case, When applying oil from above to the object (object to be oiled) 12, convection occurs in the oil application chamber, and a portion of the lubricant emitted from the electrostatic coating device (electrostatic oil application device here) floats. It adheres to the outer peripheral surface of the case body 1, and when it reaches a certain level, it flows down and drips directly from the front end of the case body 1 onto the object to be oiled, such as a plate-shaped steel plate, and the so-called oil is deposited on the surface. This method has a very serious drawback in that a thick oil film called a spot is formed, resulting in poor oil application.

In addition, when the object 12 to be coated is wide and cannot be coated completely with one electrostatic coating device, and multiple electrostatic coating devices are placed side by side for coating, the floating coating agent due to the above-mentioned convection phenomenon may occur. In addition, since the coating material emitted from adjacent electrostatic coating devices is charged with the same polarity, the coating material particles emitted to the adjacent parts repel each other and generate lifting force, as shown in Figure 1. Since it flies up and floats in the coating chamber, the amount of coating agent floating in the coating chamber increases significantly.As a result, the amount of coating agent particles adhering to the outer peripheral surface of the case body 1 also increases, and the front end of the coating agent particles increases. This has the drawback that the amount of water dripping from the paint increases, making it impossible to form a uniform coating film on the object to be coated.

In particular, when forming an extremely thin oil film of approximately 0.01 to 0.05 μm on the surface of a steel plate for rust prevention purposes during the final forming process of the steel plate, the presence of such oil spots on the steel plate may cause the following problems. When removing an oil film in the pre-treatment process in the processing process, it cannot be removed reliably, and when printing directly on a thin oil film without pre-treatment, such as in the can making process, for example, This has the disadvantage that the printing ink does not adhere well to the oil spot area, resulting in an extremely poor print finish, and there has been a strong demand to prevent the occurrence of oil spots as much as possible.

Therefore, the present invention suppresses the coating agent particles from interfering and repelling each other and flying up as described above, thereby preventing coating agent particles from adhering to the case body as much as possible, and at the same time preventing coating agent particles from floating and adhering to the case body. It is an object of the present invention to eliminate the drawbacks of the conventional device as described above by preventing dripping directly onto an object, and for this purpose, the present invention provides a device that is driven to rotate at high speed by being connected to a rotational drive source disposed inside the case body. An electrostatic coating device having a cup-shaped body to which a high voltage is applied, and configured so that the coating agent supplied to the cup-shaped body through a coating agent supply pipe is atomized by centrifugal force and electrostatic force and then radiated. A charging electrode plate is formed to extend in the circumferential direction from the outer circumferential surface of the cup-shaped body to which a high voltage of the same polarity as that of the cup-shaped body is applied, and the peripheral edge of the charged electrode plate is located at the front end of the case body. It is characterized by protruding outward from the outer part.

Hereinafter, the present invention will be explained based on specific embodiments shown in the drawings.

FIG. 2 is a front view showing an example of an electrostatic coating device according to the present invention, with main parts in cross section. In this embodiment, a charged electrode plate 20 is formed on the outer peripheral surface of the cup-shaped body 3 and extends in the circumferential direction. Further, a coating agent atomizing mechanism is applied to the coating agent supply pipe 8, and the coating agent discharge hole 21 of the coating agent supply pipe 8 is arranged to face the inner peripheral surface of the outer cylinder 4 of the cup-shaped body 3. Except for this, the configuration is substantially the same as that of the conventional device described above.

The shape of the cup-shaped body 3 is not limited to the so-called cup shape shown in the figure, but may be formed into a dish shape with a shallower depth.

The charging electrode plate 20 is a case body 1 of the cup-shaped body 3.
It is formed into a disc extending horizontally in the circumferential direction of the cup-shaped body 3 from the outer periphery of the side end facing the front end of the case body 1, and a high voltage of the same polarity as the cup-shaped body 3 is applied.

Note that, as shown in the figure, the periphery of the charged electrode plate 20 projects further outward than the front end of the case body 1.

The above is an example of the configuration of the present invention, and next, the operation when performing electrostatic oil application using the device of the present invention will be explained.

First, when the device of the present invention is placed facing downward and electrostatically applies oil to the object to be oiled from above, the cup-shaped body 3 is driven to rotate at high speed and the
While applying a high voltage of about 120 KV, the lubricating agent is atomized from the lubricating agent discharge hole 21 of the lubricant supply pipe 8 and the truncated conical surface 22 of the outer cylinder 4 of the cup-shaped body 3 is atomized.
Spray against.

The lubricant sprayed onto the truncated conical surface 22 of the outer cylinder 4 becomes a thin film due to centrifugal force and is gradually transferred to the front side. It is atomized and radiated evenly onto the object to be oiled, and is electrostatically applied to the object.

Here, the coating agent atomization mechanism that atomizes the coating agent and sprays it onto the truncated conical surface 22 of the outer cylinder 4 is applied to the coating agent supply pipe 8 in order to form an extremely thin oil film on the object to be oiled. Supply amount of lubricant to 15c.c./min
With the conventional lubricant supply pipe, droplets are once formed at the tip of the lubricant supply pipe, and once they reach a certain amount, the phenomenon of dropping drop by drop is repeated, resulting in an intermittent dripping phenomenon that causes the lubricant to be continuously applied. This is because there is a drawback that lubricant particles are intermittently emitted from the cup-shaped body 3, resulting in a so-called breathing phenomenon and uneven coating.This is to avoid this. .

This coating agent atomization mechanism will not be described with reference to drawings, but for example, a pressure of about 80 to 120 kg/cm ² is applied to the coating agent supplied to the coating agent supply pipe 8, and the liquid pressure of the coating agent causes fine particles to be formed. The so-called hydraulic atomization method, in which the lubricant is atomized by the air flow ejected from the pipe, which connects a pipe that conducts compressed air at a required pressure to the lubricant supply pipe 8, and the so-called air atomization method, in which the lubricant is atomized by the airflow ejected from the pipe. method can be applied.

However, even if an attempt is made to prevent uneven coating in this way, a part of the lubricant emitted from the cup-shaped body 3 floats due to convection and adheres to the outer peripheral surface of the case body 1, unlike in the conventional device. If the lubricant is dripped directly from the front end of the case body 1, it will cause oil spots on the surface of the object to be oiled as described above, resulting in poor lubricating, but in the present invention, the lubricant attached to the outer peripheral surface of the case body The droplets do not fall directly onto the object to be oiled, but instead are placed in the cup-shaped body 3 facing the front end of the case body 1.
Since the charging electrode plate 20 is rotated at high speed together with the cup-shaped body 3 and a high voltage is applied, the liquid drops onto the charging electrode plate 20 which is formed to extend on the outer peripheral surface of the charging electrode plate 20. It becomes atomized again and flies up, and it never forms oil spots on the object to be oiled.

In addition, even when the object to be oiled is wide and cannot be oiled with one device, and multiple devices are placed side by side to apply oil, a high voltage of the same polarity is applied to the outer periphery of the cup-shaped body 3. Since the charged electrode plate 20 is arranged, the lubricant particles that interfere with each other and tend to fly up in the adjacent parts of each device can be repelled toward the object to be coated. Therefore, there is no possibility that the lubricating agent emitted to adjacent parts of each device interferes with each other and repels each other to generate lifting force and fly up, thereby significantly increasing the floating amount of the lubricating agent, which is the case in the prior art.

Therefore, the device of the present invention is particularly suitable for the surface of steel plates.
It can be said that it is extremely useful when applied to electrostatic oil coating devices that form extremely thin oil films of about 0.01 to 0.05μ.

It should be noted that the present invention is of course applicable not only to the electrostatic oil applicator as described above, but also to a general electrostatic coating apparatus, and the coating agent supply pipe 8 is also not equipped with a coating agent atomizing mechanism and is connected to the rear surface of the partition wall 5. It may also be of a type in which droplets of lubricant are dropped onto the surface of the surface.

Next, FIG. 3 is a front view showing a main part in cross section showing another embodiment of the present invention. In this embodiment, a charged electrode plate 20 to which a high voltage is applied together with a cup-shaped body 3 is
The front end of the case body 1 is surrounded by the back side of a flat disc-shaped body 30 which is formed on the outer circumferential surface of the cup-shaped body 3 and extends in the circumferential direction, and whose extended edge is curved forward. It is formed by forming an annular protrusion 31 and drilling a plurality of through holes 32 that penetrate from the back side to the front side of the flat disc-shaped body 30 at required intervals along the inner wall of the protrusion 31. There is.

The protrusion 31 is formed perpendicularly to the flat disc-shaped body 30, and its end edge is bent inward.

Note that this protrusion 31 is not limited to the above-mentioned configuration in which the end edge portion is bent inward, and may be simply formed vertically, or may be not limited to vertically, but may be inclined inwardly. .

To explain the operation of the device of the present invention having such a configuration, when the coating agent that is floating due to the convection phenomenon and adheres to the outer circumferential surface of the case body 1 reaches a certain amount, it is transmitted along the outer circumferential surface of the case body 1. When the droplets accumulate on the outer periphery of the front end of the case body 1 and grow into a certain number of droplets, they separate from the case body 1 due to their own weight and drip downward. The dropped coating agent is received by the back surface of the flat disk-shaped body 30 of the charging electrode plate 20, which is extended from the outer peripheral surface of the cup-shaped body 3, facing the front end of the case body 1.

Here, the charging electrode plate 20 is driven to rotate at high speed integrally with the cup-shaped body 3, so that the coating agent received on the back surface of the flat disk-shaped body 30 of the charging electrode plate 20 is moved by centrifugal force. As a result, it becomes a thin film and is transferred in the direction of an annular protrusion 31 formed on the back surface of the flat disc-shaped body 30.

The thin film-like coating agent that has reached the protrusion 31 in this way is penetrated from the back side to the front side of the flat disc-shaped body 30 at required intervals along the inner wall of the protrusion 31 by centrifugal force. It moves to the front side of the flat disc-shaped body 30 through the plurality of through holes 32, and is further transferred to the extended end edge curved forward along the front face of the flat disc-shaped body 30, and from the tip thereof. The liquid is electrostatically atomized again by centrifugal force and electrostatic force, and radiated onto the object to be coated, where it is electrostatically coated.

Therefore, it is possible to completely prevent droplets of the coating agent adhering to the outer peripheral surface of the case body 1 from directly dropping onto the object to be coated, thereby causing uneven coating on the surface of the object to be coated.

Furthermore, even when electrostatic coating is performed with multiple devices arranged side by side, high voltage is applied to prevent coating particles from interfering with each other and repelling each other in the adjacent parts of each device, as in the case of the above-mentioned embodiment. The flat disk-like body 30 of the charged electrode plate 20 can reversely repel the coating agent toward the object to be coated, so that unlike the conventional technique, the coating agents emitted to adjacent parts of each device interfere with each other and are repelled. There is no possibility that the floating amount of the coating agent will increase significantly due to lifting force.

As described above, according to the present invention, the flying up of coating agent particles is suppressed to prevent coating agent particles from adhering to the case body as much as possible, and at the same time, coating agent droplets that float and adhere to the case body are protected. It has the excellent effect of not allowing drops to be applied directly onto the object to be coated, and is extremely useful especially when electrostatic painting is carried out with a plurality of devices arranged side by side facing downwards.

[Brief explanation of drawings]

FIG. 1 is a partially sectional front view showing an example of a conventional device, FIG. 2 is a partially sectional front view showing an embodiment of the present invention, and FIG. 3 is a partially sectional front view showing another embodiment of the present invention. It is a front view with a part cut away showing an example. Explanation of symbols 1... Case body, 2... Rotating shaft of air motor, 3... Cup-shaped body, 8... Coating agent supply pipe, 20... Charged electrode plate, 30... Flat disk-shaped body, 31 ... protrusion, 32 ... through hole.

Claims (1)

[Scope of Claims] 1. A cup-shaped body 3 connected to a rotational drive source disposed in a case body 1, driven to rotate at high speed, and to which a high voltage is applied; In an electrostatic coating device in which the coating material supplied through the supply pipe 8 is atomized by centrifugal force and electrostatic force and emitted, the cup-shaped body 3 extends from the outer circumferential surface of the cup-shaped body 3 in the circumferential direction. A charging electrode plate 20 to which a high voltage of the same polarity as that of the cup-shaped body 3 is applied is formed, and the periphery of the charging electrode plate 20 is projected outward from the front end of the case body 1. Electrostatic coating equipment. 2. The electrostatic coating device according to claim 1, wherein the charged electrode plate 20 is formed in a disk shape. 3 A flat disk-shaped body 3 in which the charged electrode plate 20 is formed to extend in the circumferential direction from the outer circumferential surface of the cup-shaped body 3, and the extended edge portion is curved toward the front side.
An annular protrusion 31 surrounding the front end of the case body 1 is formed on the back side of the case body 1, and the protrusion 3
1 at required intervals along the inner wall of the flat disk-shaped body 3.
A plurality of through holes 32 penetrating from the back side to the front side of 0
An electrostatic coating device according to claim 1, further comprising a perforation.