JPH08155350A - Electrostatic coating device - Google Patents

Abstract

PURPOSE: To enhance deposition efficiency of a coating material on a material to be coated by bringing the negative pole of a high voltage generator into contact with the coating material in a coating material route for feeding the coating material to a coating gun from a coating material tank and grounding the position pole thereof, the coating material tank and the material to be coated facing the coating gun. CONSTITUTION: The air spray coating gun 1 is so constituted that the coating material in the coating material tank 3 is fed by a high pressure through an insulating hose 5 by a pump 2 and is ejected in the form of mists from a nozzle 6. The positive pole of the high pressure generator 4 is grounded and the negative pole thereof is connected by a conductor 7 to a metallic electrode 8 interposed in an insulated coating material hose 5. The coating material forcibly fed in this insulated coating material hose 5 comes into contact with the electrode 8 at the time of flowing the inside of the electrode, by which the coating material is electrified with negative charges. This coating material is ejected in the form of mists from the nozzle 6 while having the negative charges and are sucked and deposited by electrostatic attraction force on the material (a) which is to be coated and is grounded with a conveyor (b). Then, the charges are efficiently electrified on the coating material and the efficient electrostatic coating is executed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrostatic coating device for applying a coating material to an article by electrostatic attraction.

[0002]

2. Description of the Related Art In a conventional electrostatic coating apparatus, a high voltage is applied to a corona pin or a rotating cup provided at the tip of a gun to form a high-potential electrostatic field with an object to be grounded. It was supposed to charge the particles.

[0003]

Therefore, in the case of the corona pin, the paint does not come into direct contact, and in the case of the rotating cup, the contact time with the paint is short and the paint is not sufficiently charged, so that the coating is not performed. There was a drawback that the coating rate on the product was low.

Further, when the resistance value is low like water-based paint, it is necessary to mount a paint path including a paint tank on an insulating frame in order to maintain the voltage at the tip of the gun. In this case, the paint path is used. It was dangerous because a high voltage was applied to it.

The present invention aims to eliminate the drawbacks of such conventional devices.

[0006]

As a means for solving such a problem, the invention of claim 1 provides a high voltage generator for a paint in a paint path for feeding the paint from a paint tank to a paint gun. The negative electrode of the high voltage generator, the positive electrode of the high voltage generator, the portion of the high voltage generator near the negative electrode of the high voltage generator to the paint tank, and the object facing the coating gun. According to the invention of claim 1, an electrode connected to the negative electrode of another high voltage generator is provided in the vicinity of the paint spraying part of the coating gun in the invention of claim 1,
The positive electrode of the high voltage generator is grounded, and the invention of claim 3 is characterized in that, in the invention of claim 2, the one high voltage generator has a characteristic that a decrease in voltage due to an increase in current is small. , The other high voltage generator has a characteristic that the voltage sharply decreases with an increase in current, and the other high voltage is caused by a rapid change in the current or voltage of the one high voltage generator. The configuration is such that a blocking device for blocking the output of the generator is provided.

[0007]

The present invention has the above-mentioned structure, and the invention of claim 1 is provided because the negative electrode of the high voltage generator is brought into contact with the paint in the paint path for feeding the paint from the paint tank to the coating gun. The electric charge efficiently charges the paint, enabling efficient electrostatic painting, and since the paint tank is grounded, the paint tank is insulated even when the paint has low electrical resistance such as water-soluble paint. There is no need to put it on a stand, it is highly safe, and there is an effect that it is possible to continuously supply the paint to the paint tank without interrupting the high voltage and interrupting the painting, and it has excellent workability. According to the invention of claim 2, since the paint in the paint path is charged as in the invention of claim 1 and an electrode is also provided at the tip of the coating gun, the paint particles are more strongly charged than the ordinary electrostatic coating. Wear rate improved On the contrary, if the coating rate is as good as the conventional one, there is an effect that the voltage of the electrode at the tip of the coating gun can be lowered and the safety is improved. Furthermore, the invention of claim 3 is the invention of claim 2. In the above, since the one high-voltage generator for charging the paint in the paint path has the characteristic that the decrease in voltage due to the increase in current is small, from near the negative electrode of the one high-voltage generator in the paint path. Even if the paint tank is grounded, the potential of the coating gun can be kept high, and other high voltage generators that apply a voltage to the electrode at the tip of the coating gun will cause the voltage to increase rapidly as the current increases. A grounding device is provided at the tip of the coating gun because it has a shutoff device that shuts off the output of the one high voltage generator due to a sudden change in the current or voltage of the other high voltage generator. When is approaching Sharply reduce the voltage of the tip of the spray gun to prevent the occurrence of spark,
The safety can be improved.

[0008]

Embodiments of the present invention will be described below with reference to the accompanying drawings.

In FIG. 1, reference numeral 1 denotes an airless spray coating gun, which is designed to pump the paint in a paint tank 3 through an insulating hose 5 at a high pressure by a pump 2 so that the paint is sprayed from a nozzle 6 in a mist state. It has become.

Reference numeral 4 denotes a high voltage generator, the positive electrode of which is grounded, and the negative electrode of which is made of a conductive wire 7 and which is interposed in an insulating paint hose 5 as shown in FIG. 8 is connected.

The present embodiment has the above-mentioned structure, and the paint which is pressure-fed in the insulating hose paint 5 is brought into contact with the paint as it flows in the electrode 8 to be negatively charged, and the nozzle is charged with the negative charge. 6 becomes a mist and is attracted and discharged by the electrostatic attraction force to the grounded object a via the ejection conveyor b.

The paint tank 3 is grounded, but the electric charge of the paint ejected from the nozzle 6 is held by the electric resistance of the paint.

If the electric resistance of the paint is small,
It suffices to use the high voltage generator 4 having the characteristic that the voltage drop is small even if the current increases.

The electrode 8 may be provided between the paint tank 3 and the pump 2.

FIG. 3 shows a modified example of the electrode 8 in which the rod-shaped electrode 8 connected to the high voltage generator 4 by the conductor 7 is inserted into the cylindrical body 9 provided in the insulating paint hose 5. It is designed to charge the paint flowing through.

FIG. 4 shows another modification of the electrode 8 in which a wire mesh electrode 8 connected to the high voltage generator 4 by a conductor 7 is housed in a cylindrical body 9 provided in an insulating paint hose 5. The paint flowing in the cylindrical body 9 is electrically charged.

FIG. 5 shows another embodiment of the present invention. In the embodiment shown in FIG. 1, another high voltage generator 10 having a positive electrode grounded is provided, and its negative electrode is provided in the vicinity of the nozzle 6 of the coating gun 1. It is connected to the electrode 11.

In the present embodiment, the coating material is charged in the liquid state by the electrode 8, and is further charged by the electrode 11 after being sprayed from the nozzle 6 and atomized. Remarkably improved.

In the present embodiment, when the high voltage generator 4 having the characteristics that the electric resistance of the paint is small and the voltage drop is small even if the current increases, the high voltage generator 10 is used.
In addition, the one having the characteristic that the voltage sharply decreases with the increase of the current is used, and the breaker for shutting off the output of the high voltage generator 4 by the rapid change of the current or the voltage of the high voltage generator 10 is used. As a result, when a grounded object approaches the coating gun 1 abnormally, the voltage at the tip of the coating gun 1 can be lowered to prevent the occurrence of fire due to sparks.

The present invention can be applied not only to airless spray coating but also to various electrostatic coating such as air spray coating and rotary cup coating.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing an outline of an embodiment of the present invention.

FIG. 2 is an enlarged sectional view of the electrode.

FIG. 3 is an enlarged cross-sectional view of a modified example of an electrode.

FIG. 4 is an enlarged cross-sectional view of another modification of the electrode.

FIG. 5 is an explanatory diagram showing the outline of another embodiment of the present invention.

[Explanation of symbols]

 1: Painting gun 2: Pump 3: Paint tank 4: High voltage generator 5: Insulating paint hose 6: Nozzle 7: Conductor 8: Electrode 10: High voltage generator 11: Electrode a: Workpiece b: Conveyor

Claims (3)

[Claims] 1. A negative electrode of one high-voltage generator is brought into contact with the paint in a paint passage for feeding paint from a paint tank to a coating gun, and the positive electrode of the high-voltage generator and the one of the one of the paint passages. An electrostatic coating apparatus, wherein a portion of the high voltage generator near the negative electrode to the coating tank and an object to be coated facing the coating gun are grounded. 2. An electrode connected to a negative electrode of another high-voltage generator is provided in the vicinity of the paint ejection portion of the coating gun, and the positive electrode of the high-voltage generator is grounded. Electrostatic coating equipment. 3. One of the high voltage generators has a characteristic that a decrease in voltage due to an increase in current is small, and the other high voltage generator rapidly decreases in voltage with an increase in current. 3. A cutoff device having characteristics and provided with a shutoff device for shutting off the output of the one high voltage generator due to a rapid change in the current or voltage of the other high voltage generator. Electrostatic coating equipment.