JPS59177152A - Electrostatic coating apparatus - Google Patents

Abstract

PURPOSE:To prevnt the adhesion of coating particles to a case body, by forming a charging electrode plate to which high voltage having the same polarity as a cup shaped body is applied to the outer peripheral surface of the cup shaped body in a state extended to the peripheral direction thereof. CONSTITUTION:An electrostatic coating apparatus is subjected to high speed rotary driving by the rotary drive source arranged in a case body 1 and has a cup shaped body 3 to which high voltage is applied while a coating agent is supplied to the cup shaped body 3 through a coating agent supply pipe 8 and injected while formed into fine particles by centrifugal force and electrostatic force. In this case, a charging electrode plate 20 to which high voltage having the same polarity as the cup shaped body 3 is applied is formed to the outer peripheral surface of the cup shaped body 3 in a state extended to the peripheral direction thereof. Therefore, the liquid droplets of the coating agent adhered to the outer peripheral surface of the case body 1 are not directly dripped on an article to be coated and dripped on the charging electrode plate 20 formed to the outer peripheral surface of the cup shaped body 3 in opposed relation to the front end part of the case body 1 and again formed into fine particles to be flied up to prevent the formation of an oil spot on the article to be coated.

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 rotary shaft 2 projects forward and is extended, and a cup-shaped body 3 is fixed to the tip thereof.

The 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 is integrally formed in the center of the partition wall 5 and gradually increases in diameter toward the partition wall 5. A slit 7 is formed at a required interval between the partition wall 5 and the outer cylinder 4, and a high voltage of about 80 to 120 KV is applied, although not shown. There are holes where the voltage is applied.

Reference numeral 8 denotes a coating agent supply pipe that supplies 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. It has been confirmed. The coating piercing 1289 opens on the side surface of the case body 1 and is connected to a coating agent supply source (not shown) via the nipple 10 and the hose 11.

The above is an example of the configuration of the conventional device shown in FIG. 1.Next, its operation will be briefly explained.
When the coating is rotated at a high speed of approximately OOOrpm and the coating is supplied to the back surface of the partition wall 5 through the coating agent supply pipe 8 in this state, the coating agent passes from the back surface of the partition wall 5 through the slit 7 and onto the inner circumferential surface of the outer cylinder 4 due to centrifugal force. The outer cylinder 4
The material is supplied in a thin film form along the inner peripheral surface of the front end 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 conventional electrostatic coating equipment, the work of applying the coating agent to the object 12 to be coated, especially the work of electrostatically applying rust preventive oil to the steel strip etc., is carried out in a sealed oil application chamber. Moreover, since the cup-shaped body 3 is driven to rotate at high speed, when applying oil to the object 12 to be coated (in this case, the object to be oiled) from above, convection occurs in the oil application chamber. occurs, and a portion of the lubricant emitted from the electrostatic coating device (electrostatic lubricating device here) floats and adheres to the outer peripheral surface of the case body 1, and when this reaches a certain level, it flows down. A very serious drawback is that the oil is dripped directly from the front end of the case body 1 onto the object to be oiled, such as a plate-shaped steel plate, and a thick oil film called an oil spot is formed on the surface of the object, resulting in poor lubrication. had.

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 they fly up and float in the coating chamber, the amount of coating agent floating in the coating chamber increases significantly, and as a result, the amount of coating agent particles that adhere to the outer peripheral surface of the case body 1 also increases, and the amount that drips from the front end of the coating agent particles increases. This has the disadvantage that a uniform coating film cannot be formed on the object to be coated.

In particular, in the final process of forming a steel plate, when an extremely thin oil film of about 0.05μ to 0.05 μm is formed on the surface for rust prevention, etc., oil spots such as those described above are present on the steel plate. Then, when removing the oil film in the pre-treatment process for the next processing process, it is not possible to remove it reliably.
Furthermore, when printing directly onto a thin oil film without pretreatment, such as in the iron making process, there is a problem that the printing ink does not adhere well to the oil spot area and the print finish is extremely poor. There was a strong demand to prevent the occurrence of 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, and prevents coating agent particles from adhering to the case body as much as possible. It is an object of the present invention to solve the above-mentioned drawbacks of the conventional device by preventing the dripping from directly onto the object, and for this purpose, the present invention provides a device that is connected to a rotational drive source disposed inside the case body and driven to rotate at high speed. An electrostatic coating device that has a cup-shaped body to which a high voltage is applied, and that supplies a coating agent to the cup-shaped body through a coating agent supply pipe, atomizes it by centrifugal force and electrostatic force, and radiates it. A charging electrode plate, to which a high voltage having the same polarity as that of the cup-shaped body is applied, is formed on the outer peripheral surface of the cup-shaped body, extending in the circumferential direction thereof.

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 taken 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 as shown in the figure, but may be formed into a dish shape with a shallower depth.

The charging electrode plate 20 is formed into a disk that extends horizontally in the circumferential direction of the cup-shaped body 3 from the outer periphery of the case body 1 side end of the cup-shaped body 3 to face the front end of the case body 1. body 3
A high voltage of the same polarity is applied.

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 a high voltage of about 80 to 120 KV is applied to the cup-shaped body 3. At the same time, the lubricant is atomized from the lubricant discharge hole 21 of the lubricant supply pipe 8 and sprayed onto the truncated conical surface 22 of the outer cylinder 4 of the cup-shaped body 3.

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, and is electrostatically atomized from the front end surface of the outer cylinder 4 by centrifugal force and electrostatic force. It is radiated evenly onto the object to be oiled and is electrostatically applied to the object to be oiled.

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. When the lubricant supply rate is lower than 15 cc/mi-n, in the conventional lubricant supply pipe, a droplet is formed at the tip of the pipe, and once a certain amount is reached, the droplets are dropped one by one, which is repeated, causing intermittent Therefore, the lubricant particles are intermittently emitted from the cup-shaped body 3, causing a so-called breathing phenomenon and causing uneven coating. This is to avoid this.

As for this coating agent atomization mechanism, although explanation with reference to the drawings is omitted, for example, the coating agent supplied to the coating agent supply pipe 8 is applied with a rate of 80 to 120 kg/cn. The so-called hydraulic atomization method applies a certain amount of pressure and atomizes the particles using the liquid pressure of the lubricant, or the lubricant supply pipe 8 is connected to a pipe that conducts compressed air at the required pressure, and the air flow is ejected from the pipe. A so-called air atomization method that atomizes the lubricant can be applied.

However, even if you try to prevent uneven coating in this way,
If 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 and drips directly from the front end of the case body 1, as in the conventional device, the object to be oiled will be However, in the present invention, droplets of the lubricant adhering to the outer peripheral surface of the case body 1 do not drip directly onto the object to be oiled. The liquid is dropped onto a charging electrode plate 20 extending on the outer peripheral surface of the cup-shaped body 3 facing the front end of the case body 1, and the charging electrode plate 20 is driven to rotate at high speed together with the cup-shaped body 3. Moreover, since a high voltage is applied, the charged electrode plate 2
0, it becomes atomized again and flies up, and no oil spots are formed 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 for oiling, a high voltage of the same polarity is applied to the outer periphery of the cup-shaped body 3. Since the electrically charged electrode plate 20 is provided, the lubricant particles that interfere with each other and tend to fly up in adjacent parts of each device can be repelled to the side of the object to be coated. Unlike in the past, there is no possibility that the lubricants emitted to the adjacent parts of each device interfere with each other and repel each other to generate lift and fly up, thereby significantly increasing the amount of floating lubricants.

Therefore, the device of the present invention can be applied to the surface of a steel plate in a range from 0°01 to 0°01.
It can be said that it is extremely useful when applied to electrostatic oil applicators that form extremely thin oil films of about 0.05 μm.

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 a coating agent are dropped on the surface.

Next, FIG. 3 is a front view showing another embodiment of the present invention with main parts in cross section. In this embodiment, the charged electrode plate 20 to which a high voltage is applied together with the cup-shaped body 3 is An annular protrusion surrounding the front end of the case body 1 is formed on the back side of the flat disk-shaped body 30, which is formed on the outer peripheral surface of the case body 3 so as to extend in the circumferential direction and whose extended edge is curved forward. A plurality of through holes 32 forming a strip 31 and penetrating the flat disc-shaped body 30 from the back side to the front side at required intervals along the inner wall of the protruding strip 31
It is formed by drilling.

The protrusion 31 is formed perpendicularly to the flat disc-shaped body 30,
Its edges are 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 formed not only vertically but also inwardly. .

To explain the operation of the device of the present invention having such a configuration, when the amount of coating agent floating due to the convection phenomenon and adhering to the outer peripheral surface of the case body 1 reaches a certain amount or more, the case body 1
The droplets flow downward along the outer peripheral surface of the case body 1, and when they accumulate on the outer circumference 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 applied to a charging electrode plate 20 extending on the outer peripheral surface of the cup-shaped body 3 facing the front end of the case body 1.
It is received on the back surface of the flat disk-shaped body 30.

Here, the charging electrode plate 20 is driven to rotate at high speed while being integrated with the cup-shaped body 3, so that the coating agent received on the back surface of the flat circular I-shaped body 30 of the charging electrode plate 20 forms a thin film due to centrifugal force. As a result, it 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
Due to centrifugal force, a plurality of through holes 32 are drilled from the back side of the flat disc-shaped body 30 forwardly at required intervals along the inner wall of the protrusion 31 to the front side of the flat disc-shaped body 30. The atomized particles are then transferred along the front surface of the flat disc-shaped body 30 to the forwardly curved extended edge, and from the tip thereof are electrostatically atomized again by centrifugal force and electrostatic force and applied to the object to be coated. It is emitted towards the target and electrostatically coats the object to be coated.

Therefore, it is possible to completely prevent the droplets of the coating agent deposited on the outer circumferential 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.

In addition, even when electrostatically coating multiple devices in parallel, high voltage is applied to the adjoining parts of each device to interfere with each other and repel the coating particles, which tend to fly up. Flat disk-shaped body 3 of the charged electrode plate 20
On the contrary, the coating agent emitted to the adjacent parts of each device interferes and repels each other, creating a lifting force and dancing. There is no significant increase at all.

As described above, according to the present invention, the flying up of coating agent particles is suppressed to prevent the coating agent particles from adhering to the case body as much as possible, and at the same time, the droplets of coating agent that float and land on the case body. It has the excellent effect of not dropping directly onto the object to be coated, and is extremely useful especially when performing electrostatic coating with multiple devices facing downward side by side.

[Brief explanation of the drawing]

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-force spout body, 8- Coating agent supply pipe, 20- Charged electrode board, 30-
Flat disk-shaped body, 31 - protrusion, 32 - through hole. Patent applicant Trinity Industries Co., Ltd.

Claims (3)

[Claims] (1) It has a cup-shaped body that is connected to a rotational drive source disposed inside the case body, is driven to rotate at high speed, and is applied with a high voltage, and a coating agent is supplied to the cup-shaped body through a coating agent supply pipe. In an electrostatic coating device that atomizes and emits particles by centrifugal force and electrostatic force, a charged electrode plate is provided to apply a high voltage of the same polarity as that of the cup-shaped body to the outer peripheral surface of the cup-shaped body. An electrostatic coating device characterized by being formed to extend in the circumferential direction. (2) The electrostatic coating device according to claim 1, wherein the charged electrode plate is formed in a disk shape. (3) The charging electrode plate is formed on the outer circumferential surface of the cup-shaped body so as to extend in the circumferential direction thereof, and the case body is attached to the back side of the flat disk-shaped body whose extended end edge is curved forward. an annular protrusion surrounding the front end of the plate, and a plurality of through holes penetrating from the back side to the front side of the flat disc-shaped body at required intervals along the inner wall of the protrusion. An electrostatic coating device according to claim 1.