JPS59145063A - Electrostatic coater - Google Patents

Abstract

PURPOSE:To continuously emit an atomized coating agent at all times for forming a uniform coating film, by providing a mechanism for atomizing a coating agent at the coating agent-ejecting nozzle of a coating agent-supplying pipe, and supplying said coating agent under a finely pulverized condition to a cup-shaped body. CONSTITUTION:A mechanism for atomizing a coating agent provided at a pipe 8 for supplying a coating agent has the double-pipe structure, for instance, comprising an inner pipe for carrying a coating agent through it and an outer pipe for the circulation of compressed air outside said inner pipe, so as to adopt the method for forming a coating agent into an air atomized state by an air stream ejected through the outer pipe. Hence, the coating agent is sprayed in a finely pulverized state through a nozzle 21 for the ejection of a coating agent onto the truncated conical surface 22 of the outer pipe 4 of a cup-shaped body 3. Consequently, the fine pulverization is continuously performed without the stagnation of the coating agent at the position of the ejection nozzle 21, so that the predetermined amount of the coating agent can be supplied to the truncated conical surface 22 at all times.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement in an electrostatic coating device that supplies a coating agent to a cup-shaped body driven to rotate at high speed, atomizes the coating agent, and radiates the coating agent.

Conventionally, this type of electrostatic coating apparatus has been constructed as shown in FIG. It protrudes forward and is extended, and has a cup-shaped body 3 at its tip.
is fixed.

The cup-shaped body 3 is formed integrally with a cylindrical outer cylinder 4, a partition wall 5 that closes the axial center of the outer cylinder 4, and a central portion of the partition wall 5, and the diameter gradually increases toward the partition wall 5 side. (It is composed of a truncated conical inner cylinder 6, a partition wall 5 and an outer cylinder 4.
A slit 7 is formed at a required interval between them, and a high voltage of about 80 to 120 KV is applied, although not shown.

8 is a rust preventive oil applied to the outer peripheral surface of the inner cylinder 6 of the cup-shaped body 3.

A coating agent passage 9 is a coating agent supply pipe that supplies coating agents such as paint and water, and is formed at the front end of the case body 1.
It is combined with The coating agent passage 9 opens on the side surface of the case body 1 and is connected to a coating agent supply source (not shown) via a nipple 10 and a hose 11.

12 is an annular air passage similarly formed at the front end of the case body 1, and is connected to a compressed air supply source (not shown) via a nipple 13 and a hose 14 arranged on the side surface of the case body 1. The compressed air supplied from the compressed air supply source is ejected forward through a large number of small holes or slits 15 bored on the front side of the case body 1, thereby creating an air flow along the outer surface of the cup-shaped body 3. form.

The above is the configuration of the conventional device shown in FIG. 1, and its operation will now be explained. OO
When the 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 flows from the back surface of the partition wall 5 into the slit 7 due to centrifugal force.
It transfers to the inner circumferential surface of the outer tube 4 through the tube, and is further supplied in the form of a thin film to the front end surface along the inner circumferential surface of the outer tube 4.

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 to an object 16 to be coated, such as a plate-shaped body. Then, the coating distribution is made uniform by the air flow blown out from the front end side of the case body 1, and the coating is electrostatically applied to the object 16 to be coated.

However, with such conventional electrostatic coating equipment, good coating can be achieved when the amount of coating agent supplied is relatively large, but when the amount of coating agent supplied is less than about 15 cc/min, the coating agent supply pipe A droplet is once formed at the tip of the coating agent supply pipe 8, and once it reaches a certain amount, the phenomenon of dropping drop by drop is repeated, resulting in a so-called intermittent dripping phenomenon. Therefore, coating agent particles are intermittently emitted from the cup-shaped body 3, causing a so-called breathing phenomenon in the coating state and causing uneven coating, which is a serious drawback. was.

In particular, when forming a thin oil film on the surface of a steel plate for rust prevention purposes in the final process of forming the steel plate, the amount of coating agent supplied should be
c/min, and in this case, the interval between each drop of coating agent dropping from the coating agent supply pipe 8 to the cup-shaped body 3 is about 10-odd seconds.
Since the steel sheet is conveyed at a high speed of approximately m 2 /min, it is almost impossible to uniformly form a thin oil film on the surface of the steel sheet, and the conventional apparatus as described above cannot be applied at all.

Furthermore, in the conventional device, the coating agent is supplied directly from the coating agent supply pipe 8 to the cup-shaped body 3, so if the coating device is installed with the entire coating device facing upward, the coating agent will overflow downward. It also has the disadvantage that it is not possible to perform a good coating operation.

Therefore, the present invention continuously atomizes and radiates the coating agent regardless of the orientation of the coating device or even when the amount of coating agent supplied is extremely small, thereby creating an even coating film on the object to be coated. The purpose of the present invention is to provide an electrostatic coating device that can form an electrostatic coating device, which has a cup-shaped body connected to a rotational drive source, driven to rotate at high speed, and to which a high voltage is applied, and which is connected to the cup-shaped body through a supply pipe. In an electrostatic coating device, a coating agent is supplied using a centrifugal force and an electrostatic force, and the atomized particles are emitted.
A coating agent atomizing mechanism is disposed in the coating agent discharge hole of the supply pipe, and the coating agent is supplied to the cup-shaped body in an atomized state.

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

FIG. 2 is a side view showing an example of the device of the present invention, with main parts taken in cross section.

In the figure, parts corresponding to those in FIG. 1 are denoted by the same reference numerals, and detailed explanation thereof will be omitted, but in this embodiment, a coating agent atomizing mechanism 18 is disposed in the coating agent supply pipe 8.

The coating agent atomizing mechanism 18, as shown in FIG.
For example, the so-called air atomization method has a double tube structure with an outer tube 2o through which compressed air of 0.1 to 1.0 Kg/cnT) is passed, and the coating agent is atomized by air flow ejected from the outer tube 20. The method is in use.

The coating agent injection hole 21 of the coating agent supply pipe 8 is arranged to face the inner circumferential surface of the outer cylinder 4 of the cup-shaped body 3.

Further, the inner circumferential surface of the outer cylinder 4 is composed of a truncated conical surface 22 whose diameter increases toward the tip, and a cylindrical inner surface 23 that communicates with the truncated conical surface 22.

The shape of the cup-shaped body 3 is not limited to the so-called cup shape as shown in FIG. 1, but may be formed into a flat circular dish shape with a shallower depth.

The above is the configuration of one embodiment of the present invention, and its operation will be explained next.

When the cup-shaped body 3 is driven to rotate at high speed, the coating agent is supplied to the inner tube 19 of the coating agent supply pipe 8 through the coating agent passage of the case body 1, and compressed air is supplied to the outer tube 20, whereby the coating agent is ejected. The coating agent that has reached the hole 21 is atomized by compressed air jetted from the outer periphery of the coating agent, and is then transferred to the cup-shaped body 3.
Therefore, the supplied coating agent is continuously atomized and sprayed onto the truncated conical surface 22 of the outer cylinder 4 without accumulation of coating agent at the position of the coating agent injection hole 21. A constant amount is always supplied onto the conical surface 22.

The coating agent sprayed in a fixed amount on the truncated conical surface 22 of the outer cylinder 4 in this way becomes a thin film due to centrifugal force and is gradually transferred to the front side. It is electrostatically atomized and uniformly radiated onto the object 16 to be coated, and is electrostatically coated onto the object 16 to be coated.

In the above-described embodiment, a so-called air atomization method in which the coating agent is atomized using atomizing air is applied as the coating agent atomization mechanism 18. However, the present invention is not limited to this method. For example, 80-120Kg/c
It is also possible to use a so-called hydraulic atomization method in which the particles are atomized only by the liquid pressure of the coating agent by applying a pressure of about J.

As described above, according to the configuration of the present invention, even if the amount of coating agent supplied is extremely small, the coating agent can be continuously supplied from the coating agent supply pipe 8 to the cup-shaped body 3 without interruption. It has been confirmed in experiments that the coating agent can be stably supplied to the cup-shaped body 3 even if the coating agent supply amount is as small as 0.1 cc/min.

Further, according to the present invention, since the coating agent jetting hole 21 is arranged facing the truncated conical surface 22 of the outer cylinder 4 of the force/knob-shaped body 3, even if the coating device is installed facing upward, Even in this case, the coating agent can be smoothly supplied to the cup-shaped body 3, and electrostatic coating can be performed reliably.

As described above, according to the present invention, since the coating agent atomizing mechanism is provided in the coating agent supply pipe that supplies coating agent to the cup-shaped body that is driven to rotate at high speed, regardless of the amount of coating agent supplied, It is possible to continuously and stably supply the lubricant to the force/knob-shaped body without causing the breathing phenomenon (
This eliminates the disadvantage of causing uneven coating on the object to be coated, and has the excellent effect that the entire coating apparatus can be installed facing upward.

[Brief explanation of the drawing]

Figure 1 is a partially sectional plan view showing a conventional device;
The figure is a side view showing an embodiment of the present invention with main parts in cross section.
FIG. 3 is an enlarged sectional view showing the coating agent supply pipe. Explanation of the symbols 1 - Case body, 2 - Rotating shaft of air motor, 3 - Cup-shaped body, 8 - Coating agent supply pipe, 18 - Coating agent atomization mechanism, 21 - Coating agent jetting 7L. Patent applicant: Trinity Industries Co., Ltd. Kawa-1-, 1. . U'-'s

Claims (1)

[Scope of Claims] (It has a cup-shaped body connected to an 11-rotation drive source, driven to rotate at high speed, and to which a high voltage is applied; a coating agent is supplied to the cup-shaped body through a supply pipe, and a centrifugal In an electrostatic coating device that atomizes and emits particles using force and electrostatic force, a coating agent atomizing mechanism is disposed in the coating agent discharge hole of the supply pipe, and the coating agent is atomized and emitted from the cup-shaped body. (2) The electrostatic coating device according to claim 1, wherein the coating agent discharge hole of the supply pipe is disposed opposite to the inner surface of the side wall of the cup-shaped body. Electrostatic painting equipment.