JPH08243441A - Electrostatic coating device - Google Patents

Abstract

PURPOSE: To provide an electrostatic coating device capable of uniformly applying electrostatic coating to the surface of material to be coated which has a complex surface shape. CONSTITUTION: This electrostatic coating device is constituted by providing a grounded housing 21 comparted into a coating chamber 22 in which powdery coating material 24 is stuck to the material 29 to be coated, such a means that powdery coating material is charged and the charged powdery coating material is classified by air current and fed to the coating chamber and flown in a dense state in the coating chamber 22, and a means for forcedly regulating the flying of the charged powdery coating material flying in a dense state in the coating chamber toward the material to be coated.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrostatic coating apparatus capable of uniformly coating a powder coating material having a complicated surface shape with a powder coating material charged on the surface. Is.

[0002]

2. Description of the Related Art Electrostatic coating is roughly classified into a system in which an electric field is formed between a grounded object using a so-called electrostatic coating gun and a charged paint is sprayed onto the object. In addition to the above, charged powder paint is densely flown into a coating chamber in which electrodes are arranged, and in that atmosphere, the electrode and the grounded object are opposed to each other to form an electric field between them and the charged powder paint is applied. There is a method in which the paint is attached to the grounded object to be painted.

In order to coat an object to be coated with the latter type of electrostatic coating device, the object to be coated is placed in a grounded state by a suspending member in a coating chamber defined in the housing. Charging the powder paint deposited on the floor of the coating room from the power supply The high voltage static electricity is transmitted to the first electrode to charge the powder paint deposited on the floor of the coating room, and the powder paint is charged particles. And flies densely inside the painting room. Further, under this condition, high-voltage static electricity is transmitted from the power source to the second electrode. As a result, high voltage static electricity is applied to the second electrode, and discharge is made from this electrode toward the grounded object to be coated, and an electric field is formed between the second electrode and the object to be coated. An electric line of force is generated, which causes the charged paint particles that fly with high density in the coating chamber to be attached to the surface of the object to be coated along the line of electric force and adhere to the surface of the object to be coated. It is said that the painting will be performed.

[0004]

However, in the latter electrostatic coating apparatus of the conventional type, when the surface of the object to be coated is a flat surface, there is no problem, but it is rather complicated. In the case of an object having a surface shape, there is a problem that so-called coating unevenness occurs, because there are areas where a large amount of powder coating adheres and areas where a small amount of powder coating adheres between parts of the surface of the object to be coated. That is, for example, in the case of an object to be coated having a complicated surface shape as shown in FIG. 3, the magnetic flux of the lines of electric force generated by the electric field formed between the electrode and the object to be coated is applied to the flat portion of the object to be coated. Since the phenomenon of being focused on the side facing the edge portion rather than the facing side occurs, more charged paint particles adhere to the edge portion, causing uneven coating. That is, since the object to be coated shown in FIG. 3 is formed with a concave portion as indicated by reference numeral 12, the lines of electric force 11 are formed on the edges 6c, 6d, 6e, 6f, 6g and 6h which define the concave portion 12. Magnetic flux concentration occurs, and this edge portion 6b
In addition, a larger amount of the charged paint particles 5a adheres, and almost no charged paint particles adhere to the inner side surface and the outer side surface of the concave portion 12. Therefore, the phenomenon that uniform coating is not performed occurs.

The present invention has been made to solve the above-mentioned inconvenience that may occur in the latter type electrostatic coating apparatus.
It is an object of the present invention to provide an electrostatic coating device capable of performing more uniform electrostatic coating even on the outer surface of an object having a complicated surface shape.

[0006]

In order to achieve the above object, the present invention defines a coating chamber for coating an object to be coated which is transported in a grounded state in a grounded housing in a transportation process. A means outside the coating room, for classifying and feeding the charged powder coating material into the coating room by an air flow,
Means for providing an atmosphere in which the charged powder coating material fed to the coating chamber in a classified state is caused to fly in a dense state in the coating chamber, and the charged powder coating material flying in the atmosphere is forcibly subjected to the above-described conveying process. A means for spraying toward the surface of the object, a means for spraying the material to be coated into the coating chamber, a means for preventing the scattering of the electrified paint from the coating chamber at the outlet from the coating chamber, and a filter at the top. The electrostatic coating device is provided with a means for purifying the exhaust gas from the coating chamber with the interposition of.

[0007]

The function of the present invention is as follows.
Blow air into the coating chamber to discharge the charged paint into the coating chamber and fly it in high density to adhere to the surface of the grounded object by electrostatic action. To make the distribution state of flying as uniform as possible,
By passing the coating object through the air blowing frame in that atmosphere, the charged paint particles that fly densely and evenly into the coating chamber are forced toward the coating object by the air ejected from the nozzle of the air blowing frame. Will be sprayed. For this reason, a large amount of charged paint particles are sprayed in a short time in a short time by forcibly spraying the charged paint particles that fly in a dense and uniform state by electrostatic action and stirring by blowing air toward the object to be coated. Adheres to the surface of the object to be coated, which has a complicated surface shape, and provides uniform coating.

[0008]

1 and 2 are views showing an embodiment of an electrostatic coating apparatus according to the present invention. FIG. 1 is a vertical sectional front view of the electrostatic coating apparatus according to the above embodiment, and FIG. 2 is a transverse sectional view of the apparatus shown in FIG.

In these figures, reference numeral 21 is a housing, 22 is a coating chamber formed inside the housing 21,
23 is a paint storage tank disposed on both sides of the housing 21, 24 is powder paint stored in the paint storage tank 23, 25 is a paint passage for sending the powder paint 24 from the paint storage tank 23 to the coating chamber 22, Reference numeral 26 is a nozzle arranged between the paint passage 25 and the coating chamber 22, and 27 is a nozzle 26.
Electrodes provided therein, 28 is an air blowing frame which is arranged in the coating chamber 22 so as to surround the object to be coated, and 29 is a part of the housing 21 which passes through the inside of the air blowing frame 28 and is quiet while being conveyed. An object to be coated to be electrocoated, 30 is an inlet to the object for carrying the object 29 into the housing 21,
Reference numeral 31 is an outlet for the object to be coated for carrying out the object 29 to be coated from the housing. 32 is a filter provided near the ceiling of the coating chamber 22, 33 is a first electrode disposed below the filter 32 in the coating chamber, and 34 is a second electrode provided on the side wall of the object inlet 30. An electrode, 35 is a third electrode provided on the side wall of the article outlet 31, a 36 is a first air nozzle provided at the inlet end of the article inlet 30, and 37 is an outlet end of the article outlet 31. A second air nozzle 38 provided in the section is an article-conveying member that suspends and supports the article 29 to be coated and conveys it inside the housing 21.

The structure and function of the present invention will be described below with reference to the drawings. A paint supply port 40 for introducing the powder paint 24 is provided above the paint storage tank 23. This paint supply port 40 is provided with a lid member 41 that can be opened and closed. A first air outlet 39 is provided inside the paint storage tank 23, and the blown air can pass therethrough, and a support plate 46 having a porous structure for supporting the powder paint 24 in a deposited state is provided. The powder paint 24, which is set and is put into the paint storage tank 23, is deposited on the support plate 46. An air valve 42 for appropriately adjusting the amount of air supplied from the first air outlet 39 is provided at the top of the paint passage 25 communicating with the paint storage tank 23. Therefore, in the paint storage tank 23, the powder paint 24 is lifted up by the air sent from the first air blowing port 39, and the particles are classified and sent to the paint passage 25 in a flying state. Has a role as a tank. Then, by adjusting the opening and closing of the air valve 42 provided at the top of the paint passage 25, the paint passage 2
It is possible to adjust the amount of the powder coating material 24 that is sent to the inside 5 in the flying state.

A second air blowing port 43 is provided at the bottom of the housing 21, and an air exhaust port 44 is provided at the top of the housing 21 with a filter 32 interposed. This structure has a coating chamber 22 inside the housing 21.
The reason is that the powder paint which is sent from the paint passage 25 into the paint chamber 22 by the air blown from the second air outlet 43 and flies in a dense state is uniformly classified to create a density. Further, the filter 32 is configured to exhaust excess air blown into the coating chamber 22 from the housing 21 as clean air by removing the powder coating material 24 by applying it to the filter 32. This housing 21 is ground 4
5 and is set to the potential O.

The air blowing frame 28 is made of an insulating material such as vinyl chloride, and serves as a moving passage for the article to be coated 29 which is suspended by the suspending member of the article conveying member 38 and moves inside the coating chamber 22. The pipe member is bent to have a shape surrounding the object to be coated 29 so that the object to be coated 29 can pass through the portion. A plurality of nozzles 46 are provided on the inner surface of the air blowing frame 28 to inject air toward the object to be coated 29 which is surrounded by the air blowing frame 28 and passes through the inside thereof. It is itself connected to an air supply (not shown). As shown in FIG. 2, such an air blowing frame 28 is provided in the coating chamber 2
A plurality of objects to be coated 29 are provided at a predetermined interval in the inside of the sheet 2.

Paint passage 25 Paint chamber 2 in housing 21
As is clear from FIGS. 1 and 2, a flat nozzle 26, that is, a nozzle constituted by a slit-shaped passage extending in the vertical direction is used as the nozzle 26 that communicates with the nozzle 2. An electrode 27 is arranged inside the nozzle 26. Negative high voltage static electricity is applied to the electrode 27. This electrode 27 is a paint passage 25
The paint particles sent from the coating chamber 22 to the painting chamber 22 are charged negatively charged particles 24a. Further, the first to third electrodes 33, 34, 35 are provided in the coating chamber 22 in the housing 21.
The coating object entrance 30 for feeding the coating object 29 to the coating room 2 and the coating chamber 2
It is provided in the vicinity of the object outlet 31 for taking out the object whose coating is completed from No. 2 and in the vicinity of the air discharge port 44 provided at the top of the housing 21. These electrodes are
At each location, the electrostatically charged repulsive force is applied to the charged paint particles 24a, which are filled in the coating chamber 22 and fly in a dense state, to separate the charged paint particles 24a from the flow of the air flowing out from the coating chamber 22 so that the charged paint is discharged. It is for preventing scattering to the outside of 22. Therefore, a negative voltage is applied to the first to third electrodes 33, 34, 35. Further, the first and second air nozzles 36 and 37 provided at the ends of the article inlet 30 and the article outlet 31 blow high pressure air toward the inside of the housing 21.

The operation of the electrostatic coating device thus constructed will be described below. First, the electrode 27 and the first, second,
Air is supplied from the first and second air outlets 39, 43 and air to the air outlet frame 28 while negative high voltage static electricity is applied to the third electrodes 33, 34, 35. Air is jetted from the nozzle 46.
As a result, in the paint storage tank 23, the powder paint 24 is lifted up by the air blown from the first air outlet 39, and the powder paint which is its particles is classified and sent to the paint passage 25. The amount of particles of the powder paint 24 supplied to the paint passage 25 is adjusted by opening and closing the air valve 42. The powder paint 24 flows from the paint passage 25 through the nozzle 26 into the paint chamber 22. At this time, the coating powder is negatively charged by the electrode 27 provided in the nozzle 26 to become the charged coating particles 24a. Then, the charged paint particles 24a fly into the coating chamber 22 in a dense state.

In the coating chamber 22, an object to be coated 29 to be coated is conveyed from an object to be coated inlet 30 to a member to be coated 38.
Suspended by and carried in. The potential of the object to be coated 29 is set to 0 by the earth 45, and the charged paint particles 24a flowing into the coating chamber 22 are negatively charged.
Even if it is sent into the coating chamber 22 through 7 it is attracted to the article 29 to be coated by electrostatic action and adheres to the surface thereof. When the coating of the object 29 to be coated is completed, the object 29 to be coated is carried out from the outlet 31 of the object to be coated. In this embodiment, the charged paint particles 24a flowing into the coating chamber 22 are agitated by the air blown from the second air outlet 43, and the article to be coated 29 passes through the inside of the air blowing frame 28. The charged paint is forcibly blown toward the surface of the article to be coated 29 by the air blown from the nozzle 46 of the air blowing frame 28 during the passage. Therefore, the coating of the object to be coated 29 is performed by electrostatic action in the coating chamber 22 and the charged paint flying in the coating chamber 22 in a dense state from the nozzle 46 of the air blowing frame 28 toward the object to be coated 29. By exerting the function of forcibly adhering the electrified paint by using the air accelerating action by the air blowing, the large amount of electrified paint particles 24a adhere to the surface of the object 29 to be coated in a short time. Is applied.

In the electrostatic coating apparatus according to the present invention, a large amount of electrostatic charge is generated by the action of forcibly flying the charged powder coating flying in the coating chamber 22 in a dense state onto the object to be coated by air. The paint particles 24a are applied to the surface of the article 29 to be coated for coating. That is, the present embodiment does not include a high-voltage electrode for generating lines of electric force between the object to be coated 29 and realizes an electrostatic coating apparatus without electric field. Therefore, even if the object to be coated 29 has an edge portion or a concave portion defined by the edge (see FIG. 3), the electrode and the object to be coated face each other. Unlike the method of causing the electric field lines, the concentration of electric lines of force due to the electric field shape does not occur between the two. Therefore, the coating object 29 having a complicated surface shape is formed.
However, almost the same amount of the powder coating material 24 is forcibly adhered to the entire surface regardless of the surface shape, and uniform and even coating can be realized.

The charged paint particles 24a that have not adhered to the article to be coated 29 tend to come out of the housing 21 from the air outlet 44, or pass through the article inlet 30 and the article outlet 31. Attempt to go out of the coating chamber 22 of the housing 21. However, since the first electrode 33 to which a negative voltage is applied is provided near the air discharge port 44, the charged paint particles 24a repel each other with the first electrode 33 and stay in the coating chamber 22. To be Further, since the filter 32 is provided in the front part of the air discharge port 44, the charged paint particles 24 that have passed through the first electrode 33.
The a is filtered by the filter 32 and remains in the coating chamber 22. Further, since the second and third powder separation electrodes 34 and 35 to which a negative voltage is applied are provided near the object inlet 30 and the object outlet 31, the charged paint particles 24a are separated from these second particles. And the third powder separation electrodes 34, 3
5 repels each other and is retained in the coating chamber 22. Furthermore, first and second air nozzles 36 and 37 are provided at the ends of the object inlet 30 and the object outlet 31. The first and second air nozzles 36 and 37 are located inside the housing 21. Since the high-pressure air is blown toward one side, the charged paint particles 24a are prevented from scattering from the coating chamber 22 of the housing 21 by the high-pressure air, and
It is kept inside.

[0018]

As described above, according to the present invention,
The electrostatic coating device defines a coating chamber in which the powder coating material charged on the object to be coated is applied in the grounded housing to form a coating chamber, and a nozzle for controlling the flight of the powder coating material by the air flow,
An air injection port configured by an electrode for charging particles of the powder coating material fed into the coating chamber and a grounded conveying means for setting the potential of the object to be coated to zero, and for supplying air into the coating chamber in the housing. And an air outlet for letting out air, or an air blowing frame that blows air toward the object to be coated along the movement path of the object to be coated in the coating chamber, so that the charged particles of the powder coating can be removed By the action of electricity and the action of stirring and accelerating with high-pressure air, a large amount can be attached to the surface of the article to be coated in a short time.

Further, since the electric fieldless electrostatic coating is realized,
Even if the object to be coated has edge portions or recesses, the lines of electric force do not concentrate, and almost the same amount of powder paint is supplied and adheres to the entire surface of the object to be coated, and uniform and even coating is achieved. Can be realized. And because of this aspect, it is necessary to apply a degree of coating that is difficult to apply,
Excessive paint will not be attached to other parts, and it is possible to prevent waste of paint, etc.
Various effects can be obtained.

[Brief description of drawings]

FIG. 1 is a vertical sectional view showing an embodiment of an electrostatic coating apparatus according to the present invention.

2 is a cross-sectional view of the device shown in FIG.

FIG. 3 is a perspective view showing a structural example of an object to be coated which is coated by an electrostatic coating device.

[Explanation of symbols]

 21 Housing 22 Coating Room 23 Paint Storage Tank 24 Powder Paint 26 Nozzle 27 Electrode 28 Air Blowing Frame 29 Object to be Paint 32 Filter 33, 34, 35 Electrode

Claims (1)

[Claims] 1. A powder charged in a grounded housing to define a coating chamber for coating an object to be coated which is transported in a grounded state during the transportation process, and which is outside the coating chamber and is charged in the coating chamber. A means for classifying and feeding paint by air flow,
Means for providing an atmosphere in which the charged powder coating material fed to the coating chamber in a classified state is caused to fly in a dense state in the coating chamber, and the charged powder coating material flying in the atmosphere is forcibly subjected to the above-described conveying process. A means for spraying toward the surface of the object, a means for spraying the material to be coated into the coating chamber, a means for preventing the scattering of the electrified paint from the coating chamber at the outlet from the coating chamber, and a filter at the top. An electrostatic coating apparatus comprising means for purifying exhaust gas from a coating chamber through an intermediary of the above.