JP2018192380A - Electrostatic powder coating device - Google Patents

Abstract

To provide an electrostatic powder coating device capable of heightening coating efficiency and coating quality, and avoiding coating defect.SOLUTION: An electrostatic powder coating device 1 has a nozzle 20 for forming a jet flow 81 of powder in a direction along the surface 91 of a coating object 9 by spraying the powder 8, a needle-like discharge electrode 30 installed toward the coating object 9 on the opposite side to the coating object 9 across the jet flow 81, and a case 10 for storing the coating object 9, the nozzle 20 and the needle-like discharge electrode 30. A counter electrode 40 is installed along the coating object 9, and corona discharge 31 is formed between itself and the needle-like discharge electrode 30.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an electrostatic powder coating apparatus.

For example, in the production of an electrode for a lithium ion battery, an electrostatic powder coating method is employed when applying a powder that becomes an electrode layer on the surface of an electrode substrate.
In the electrostatic powder coating method, charged powder is electrostatically adsorbed on the surface of an object to be coated. Among these, in the corona charging type electrostatic powder coating method, a needle-like discharge electrode for corona discharge is used to charge the powder. In coating, a corona discharge is generated between the electrode and the object to be coated to form a charged space region, and powder is supplied into the charged space region for charging. The charged powder is electrostatically adsorbed to the object to be coated, whereby the powder is applied to the object to be coated.

As the above-described corona charging type electrostatic powder coating method, several types are used in which the position of the electrode with respect to the object to be coated and the supply direction of the powder are different.
In the first type, a gun nozzle that sprays powder toward the surface of an object to be coated is arranged, and a needle-like discharge electrode is coaxially installed at the center of the tip of the gun nozzle. When powder is quantitatively supplied to the gun nozzle, the powder is charged by the electrode when sprayed from the tip and sprayed onto the surface of the object to be coated (Patent Document 1).
In the first type, the gun nozzle and the electrode are integrally formed, and the spray direction of the gun nozzle and the direction of corona discharge by the electrode (from the electrode toward the object to be coated) are the same.

In the second type, an object to be coated is arranged horizontally, a baffle plate is arranged above it, and a gun nozzle is arranged toward the baffle plate. Needle-like discharge electrodes (corona pins) are provided on the front and lower ends of the baffle plate. When powder is sprayed together with gas from the gun nozzle, the powder collides with the baffle plate and descends. The descending powder is charged by an electrode and dropped onto the surface of an object to be coated (Patent Document 2).
In the second type, the spray direction of the gun nozzle is the direction along the surface of the object to be coated, but the moving direction of the powder adhering to the object to be coated and the direction of corona discharge (from the electrode toward the object to be coated) are Are the same.

In the third type, the object to be coated is accommodated in a housing arranged in the vertical direction. At the intermediate height in the housing, needle-like discharge electrodes are arranged in the horizontal direction toward the object to be coated, and a powder nozzle is arranged in the lower part of the housing. In a state where a corona discharge is formed from the needle-shaped discharge electrode toward the object to be coated, the powder that rises is slowly blown up from the nozzle in an air current, and the rising powder is charged by the corona discharge, and is then transferred to the object to be coated. It is adsorbed on the surface of the object to be coated by changing its direction (Patent Document 3).
In the third type, the corona discharge is in the horizontal direction, and the vertical direction in which the powder is blown is a tolerance direction.

JP 2011-77014 A Japanese Patent Laid-Open No. 62-193664 Japanese Patent No. 5751902

Each type of the electrostatic powder coating method described above has the following disadvantages when applied to the formation of an electrode layer such as an electrode for a lithium ion battery.
In the first type, the powder is sprayed vigorously from the tip of the gun nozzle toward the surface of the object to be coated. For this reason, when an electrode material having a relatively large specific gravity as compared with a synthetic resin material is used for the powder, the sprayed powder easily rebounds due to the reaction force when it collides with the object to be coated. The adhesion efficiency to the object to be coated decreases, the coating efficiency decreases and the coating quality also decreases.

  In the second type, the electrode material used as powder is relatively small particles having a particle diameter of several μm to several tens of μm. For this reason, the powder which collided with the baffle plate is hardened on the surface of the baffle plate, causing clogging in a short period of time, and separation of the powder and gas on the baffle plate becomes insufficient, resulting in a decrease in coating efficiency. In addition, after the powder has hardened on the surface of the baffle plate or needle-like discharge electrode, it may fall off from each surface as a lump of powder and adhere to the surface of the object to be coated. It can happen.

  In the third type, since it is difficult to keep the amount (concentration) of the powder sprayed into the housing constant, the variation in the film thickness in the width direction and the conveyance direction of the object to be coated becomes large, and the coating quality is deteriorated. . Moreover, the powder adhering to the acicular discharge electrode may fall off and adhere to the object to be coated as a lump, which may cause poor coating.

  An object of the present invention is to provide an electrostatic powder coating apparatus that can improve coating efficiency and coating quality and can avoid poor coating.

  The electrostatic powder coating apparatus according to the present invention includes a nozzle that sprays powder to form a jet of the powder in a direction along the surface of the object to be coated, and is opposite to the object to be coated across the jet. It has a needle-like discharge electrode installed toward the object to be coated, and a case surrounding the surface of the object, the nozzle and the needle-like discharge electrode.

In the present invention, the powder sprayed from the nozzle becomes a jet in a direction along the surface of the object to be coated. The powder in the form of a jet is charged by corona discharge from the needle-shaped discharge electrode toward the surface of the object to be coated, and is electrostatically attracted to the object to be coated as the flow velocity of the jet decreases away from the nozzle. Adsorbed.
Therefore, in the present invention, since the powder jet is in the direction along the surface of the object to be coated, the powder does not rebound on the object to be coated and the coating efficiency is not lowered. Further, since a baffle plate or the like is not used, coating efficiency is not reduced due to clogging.
Furthermore, in the present invention, the acicular discharge electrode can be arranged outside the powder jet, thereby suppressing the adhesion of the powder to the electrode, and the lump of powder adhering to the electrode adheres to the surface of the object to be coated. This will not cause poor painting.
In the present invention, the case only needs to be able to cover the surface to be coated of the object to be coated, and may accommodate a part of the object to be coated or the entire object to be coated.

  In the electrostatic powder coating apparatus of the present invention, it is desirable that the needle-like discharge electrode is installed outside the jet.

On the outside of the jet of powder injected from the nozzle, the powder gradually decelerated with respect to the powder in the jet is distributed, and a clear boundary is not defined. However, it is possible to identify the position where the powder flowing as a jet is sprayed as the inside of the jet, and the position away until the spray as the jet disappears as the outside of the powder. In this invention, an electrode should just be arrange | positioned in the position which is away from a jet flow and a powder is not sprayed.
In the present invention, the acicular discharge electrode can be disposed outside the powder jet, and the lump of powder adhering to the electrode does not adhere to the surface of the object to be coated and does not cause poor coating.
In the present invention, since the acicular discharge electrode is arranged outside the jet of powder, the adhesion of the powder to the electrode can be suppressed, the lump of powder attached to the electrode adheres to the surface of the object to be coated, It is possible to avoid poor coating.

  In the electrostatic powder coating apparatus according to the present invention, the nozzle is an air nozzle that injects a gas for conveyance and that is supplied with a fixed amount of powder from a side of the gas flow passing through the nozzle. preferable.

  In the present invention, the powder supplied in a constant amount is sucked into a gas flow by the Venturi effect, dispersed in the gas flow, and jetted to form a powder jet. By supplying a fixed amount of powder to such a venturi-type air nozzle, the concentration of the powder in the powder jet can be kept constant, and the coating quality can be improved.

In the electrostatic powder coating apparatus of the present invention, it is preferable that the surface of the object to be coated is arranged in the vertical direction.
In the present invention, even if there is a foreign substance or the like, it can fall downward and avoid adhesion to the object to be coated. In addition, the area occupied by the facility can be made compact.

In the electrostatic powder coating apparatus of the present invention, it is preferable that the nozzle blows the powder upward from below the needle-like discharge electrode.
In the present invention, the correctly sprayed powder rises from the nozzle, is charged by the needle-like discharge electrode, and adheres to the surface of the object to be coated. On the other hand, even if a part of the powder sprayed from the nozzle may become a lump, the lump of powder falls by its own weight and can be prevented from adhering to the object to be coated.

  In the electrostatic powder coating apparatus of the present invention, it is preferable that a counter electrode facing the needle-like discharge electrode is provided between the object to be coated and the needle-like discharge electrode.

In the present invention, the counter electrode can be installed along the surface of the object to be coated. The counter electrode can arbitrarily set the distance from the surface of the object to be coated (or the distance from the acicular discharge electrode). The nozzle may be installed so that the powder jet passes between the counter electrode and the acicular discharge electrode. The counter electrode is kept at the same potential as the object to be coated. Usually, both the counter electrode and the object to be coated are electrically grounded.
In the present invention, since the distance from the acicular discharge electrode to the counter electrode is shorter than the distance from the acicular discharge electrode to the surface of the object to be coated, even if the voltage applied to the acicular discharge electrode is the same, the acicular discharge Corona discharge between the electrode and the counter electrode can be strengthened, and the powder can be charged efficiently.

In the electrostatic powder coating apparatus of the present invention, it is preferable that an air brush for cleaning the surface of the counter electrode facing the needle-like discharge electrode is installed.
In the present invention, the surface of the counter electrode can be cleaned with an air brush. For this reason, even if the powder adheres to the surface of the counter electrode, for example, by operating the airbrush at a time not during the coating operation, it is possible to prevent the powder from growing to a lump and adhering to the object to be coated.

  In the electrostatic powder coating apparatus according to the present invention, the counter electrode is formed in a plate shape and is supported rotatably around a rotation axis in a direction intersecting the surface, and a part of the counter electrode faces the needle discharge electrode. It is preferable that the rotating counter electrode is disposed outside and the other part is disposed outside the case.

  In the present invention, the portion disposed facing the acicular discharge electrode functions as a counter electrode, and the powder adhering to the surface can be removed from the portion disposed outside the case. The rotary counter electrode can be, for example, a disk-shaped electrode, and can be rotated using a motor or the like. By rotating such an electrode, the part functioning as the counter electrode and the part from which the powder is removed can be changed by a predetermined angle. The rotary counter electrode may be continuously rotated during the coating operation, may be rotated intermittently at regular intervals, or may be rotated when the operation is stopped.

  In the electrostatic powder coating apparatus of the present invention, the counter electrode is formed of a plurality of electrode plates, and any one of the electrode plates is disposed to face the needle-like discharge electrode, and the other electrode plates Is preferably an advancing / retracting counter electrode disposed outside the case.

  In the present invention, the electrode plate arranged to face the needle-like discharge electrode functions as a counter electrode, and the electrode plate arranged outside the case can remove the powder adhering to the surface. The advancing and retracting counter electrode can be configured to advance and retract each electrode plate using a motor or the like. The operation of changing the electrode plate may be performed at regular intervals during the coating operation, or may be performed when the operation is stopped.

  ADVANTAGE OF THE INVENTION According to this invention, coating efficiency and coating quality can be improved and the electrostatic powder coating apparatus which can avoid a coating defect can be provided.

The side view which shows 1st Embodiment of this invention. The front view which shows the said 1st Embodiment. The top view which shows the said 1st Embodiment. The side view which shows 2nd Embodiment of this invention. The side view which shows 3rd Embodiment of this invention. The top view which shows the said 3rd Embodiment. The side view which shows 4th Embodiment of this invention. The side view which shows 5th Embodiment of this invention. The top view which shows the said 5th Embodiment. The side view which shows 6th Embodiment of this invention. The top view which shows the said 6th Embodiment.

[First Embodiment]
1 to 3 show a first embodiment of the present invention.
In FIG. 1, an electrostatic powder coating apparatus 1 is an apparatus that performs coating by electrostatically adsorbing powder 8 on the surface of an object 9 to be coated.

The electrostatic powder coating apparatus 1 has a box-shaped case 10 that is long in the height direction. The case 10 has an opening 11 on the back surface, and an object 9 is disposed so as to close the opening 11.
The object to be coated 9 is, for example, a belt-shaped member that is unwound from a roll, and is sent to the roller 12 from the lower left side in FIG. Sent to a roll (not shown).

The electrostatic powder coating apparatus 1 electrostatically adsorbs the powder 8 on the surface 91 when the article 9 is sent along the opening 11, thereby forming a coating film 92 made of the powder 8. .
In order to perform such processing, the case 10 includes a nozzle 20 that sprays the powder 8 in the case 10, a needle-like discharge electrode 30 that charges the sprayed powder 8, and the needle-like discharge electrode 30. A rotary counter electrode 40 disposed opposite to the counter is disposed.
A dust collector 15 is connected to the bottom surface of the case 10 in order to suck dust such as powder 8 that has not been adsorbed to the article 9.

The nozzle 20 is installed on the upper surface of the case 10 in a downward direction toward the inside of the case 10, that is, in a direction along the surface 91 of the article 9 to be coated. The nozzle 20 is connected to a powder quantitative supply device 21 and a high-pressure air supply device 22.
The powder quantitative supply device 21 supplies a constant amount of the powder 8 to the nozzle 20 per time.
The high pressure air supply device 22 supplies high pressure air having a predetermined pressure to the nozzle 20 at a constant flow rate per hour.

Inside the nozzle 20, a supply pipe for the powder 8 is connected to the side of the high-pressure air flow path, and the powder 8 is sucked out by the Venturi effect of the high-pressure air and dispersed into the high-pressure air. The high-pressure air in which the powder 8 is dispersed is sprayed downward from the nozzle 20 into the case 10 to form a jet 81 containing the powder 8.
As shown in FIG. 3, the nozzle 20 is installed so that the jet 81 formed by spraying the powder 8 penetrates the corona discharge 31 from the needle-like discharge electrode 30 to the counter electrode 40.

The acicular discharge electrode 30 is installed on the upper part of the case 10 so as to face the opening 11. A power supply device 32 is connected to the acicular discharge electrode 30.
The acicular discharge electrode 30 is applied with a high voltage (10 to 100 KV) from the power supply device 32, and forms a corona discharge 31 toward the counter electrode 40.

The counter electrode 40 has a disk-shaped electrode plate 41 as shown in FIG. The electrode plate 41 is disposed through a slit or the like on the upper surface of the case 10 (where the nozzle 20 is installed). The lower half region 411 of the electrode plate 41 is exposed inside the case 10, and the other region 412. Is housed in a cover 14 that covers the upper surface of the case 10.
Among these, the area | region in the case 10 of the electrode plate 41 is arrange | positioned in the state which opposes the acicular discharge electrode 30 in the vicinity of the surface 91 of the to-be-coated object 9 which faces the opening 11 of the case 10. FIG. The distance between the electrode plate 41 and the needle-like discharge electrode 30 is formed several times larger than the distance between the electrode plate 41 and the surface 91 of the article 9 to be coated. In addition, by installing in such a positional relationship, the acicular discharge electrode 30 is installed with a sufficient distance outside the jet 81.

The electrode plate 41 is rotationally driven by a motor 42 (see FIG. 1), and the region 411 exposed inside the case 10 and the region 412 accommodated inside the cover 14 are gradually switched.
A wiper 43 for wiping the surface of the electrode plate 41 is installed inside the cover 14, and a dust removing device 44 for collecting dust removed from the surface of the electrode plate 41 is connected to the wiper 43.

Of the surface of the electrode plate 41, the powder 8 adheres to the region 411 in the case 10. As the electrode plate 41 rotates, the portion to which the powder 8 is attached gradually moves to the region 412 in the cover 14. When the electrode plate 41 further rotates and reaches the wiper 43, the powder 8 adhering to the surface is removed, and then returns to the region 411 in the case 10 again. Therefore, even if the powder 8 adheres to the surface of the electrode plate 41, it can be removed.
The rotation operation of the electrode plate 41 may be performed continuously continuously during the painting operation. Alternatively, intermittent operation may be repeated. Ordinarily, the electrode plate 41 may be stopped and operated half a turn at predetermined time intervals.

In such an electrostatic powder coating apparatus 1, electrostatic powder coating is performed on the object 9 by the following procedure.
First, a corona discharge 31 is formed from the needle-like discharge electrode 30 toward the counter electrode 40, and a powder 8 and high-pressure air are supplied to the nozzle 20 to form a downward jet 81 that penetrates the corona discharge 31. To do.
The powder 8 contained in the jet 81 is charged to a high voltage while passing through the corona discharge 31, and after passing through the corona discharge 31, the powder 8 is statically applied to the surface 91 of the object 9 that is maintained at the ground potential. Electroadsorption is performed to form a coating film 92 made of the powder 8.
The article 9 on which the coating film 92 is formed on the surface 91 is sequentially sent upward and taken out.

  During operation, a part of the powder 8 sprayed from the nozzle 20 adheres to the surface of the counter electrode 40 (the region 411 in the case 10 of the electrode plate 41). The adhered powder 8 moves to the region 412 in the cover 14 as the electrode plate 41 rotates, and is removed by the wiper 43. The electrode plate 41 from which the adhered powder 8 has been removed returns to the region 411 again. Thereby, the surface of the counter electrode 40 is always maintained in a clean state, and an appropriate corona discharge 31 can be maintained.

According to this embodiment, the following effects can be obtained.
In this embodiment, since the jet 81 of the powder 8 is in the direction along the surface 91 of the object 9, the powder 8 does not bounce off the object 9 and cause a reduction in coating efficiency. Further, since a baffle plate or the like is not used, coating efficiency is not reduced due to clogging.

In the present embodiment, since the jet 81 from the nozzle 20 is disposed so as to penetrate the corona discharge 31 formed between the needle-shaped discharge electrode 30 and the counter electrode 40, the needle-shaped discharge electrode 30 and the counter electrode 40 are Each can be outside the jet 81.
The needle-shaped discharge electrode 30 and the counter electrode 40 are arranged at a sufficient distance outside the jet 81, so that the adhesion of the powder 8 to the needle-shaped discharge electrode 30 and the counter electrode 40 is greatly reduced or prevented. it can.
Further, the adhesion of the powder 8 to the needle-like discharge electrode 30 and the counter electrode 40 is suppressed, so that the lump of the powder 8 that has adhered and grown is peeled off, and the surface 91 or the coating film 92 of the object 9 is coated. It will not adhere to the surface and cause poor painting.

In particular, the counter electrode 40 close to the object to be coated 9 is configured to include the rotary electrode plate 41 and the wiper 43 so that the surface of the electrode plate 41 can be wiped with the wiper 43 and kept clean at all times. it can.
As a result, it is possible to avoid the lump of the powder 8 in the vicinity of the object 9 and to stably obtain an appropriate corona discharge 31 by the counter electrode 40 whose surface is kept clean.

In the present embodiment, the powder 8 is quantitatively supplied by the powder quantitative supply device 21, and the powder 8 quantitatively supplied to the nozzle 20 is a gas flow due to the venturi effect by the high-pressure air from the high-pressure air supply device 22. Can be sucked out, dispersed in a gas flow and sprayed to form a jet 81 of powder 8.
Thus, by using a venturi-type air nozzle as the nozzle 20 and supplying the powder 8 in a constant amount, the concentration of the powder 8 in the jet 81 can be kept constant, and the coating quality can be improved.

In the electrostatic powder coating apparatus 1 of the present embodiment, since the surface 91 to be coated of the article 9 is arranged in the vertical direction, from the inner surface of the case 10, the acicular discharge electrode 30, the counter electrode 40, and the like. Even if there is a foreign matter such as a lump of the powder 8 that has been peeled off, this foreign matter will drop as it is, and adhesion to the object 9 can be avoided.
Moreover, since it becomes an installation of a vertical direction including the case 10, the exclusive area of an installation can be made compact.

  In the present embodiment, the counter electrode 40 is configured such that the distance from the needle-shaped discharge electrode 30 to the counter electrode 40 is greater than the distance from the needle-shaped discharge electrode 30 to the surface 91 of the object 9 to be coated. It becomes shorter by the distance of 9. For this reason, even if the voltage applied to the acicular discharge electrode 30 is the same, the corona discharge 31 between the acicular discharge electrode 30 and the counter electrode 40 can be strengthened, and the powder 8 can be charged efficiently. .

[Second Embodiment]
FIG. 4 shows a second embodiment of the present invention.
The electrostatic powder coating apparatus 2 of the present embodiment is similar to the electrostatic powder coating apparatus 1 of the first embodiment described above, the object 9, the case 10, the nozzle 20, the acicular discharge electrode 30, and the rotary type. A counter electrode 40 is provided.
However, in this embodiment, the case 10 is installed upside down with respect to the first embodiment. That is, the case 10 has a cover 14 on the bottom surface side, the needle-like discharge electrode 30 and the rotating counter electrode 40 are installed near the bottom surface of the case 10, and the nozzle 20 is installed upward therebetween.

Also according to this embodiment, the same effect as that of the first embodiment described above can be obtained.
Furthermore, since the nozzle 20, the acicular discharge electrode 30 and the counter electrode 40 are installed near the bottom surface of the case 10, the lump of the powder 8 adhering to the acicular discharge electrode 30 and the counter electrode 40 is peeled off and dropped. However, adhesion of the article 9 and the surface 91 positioned above these to the coating film 92 can be avoided.

[Third Embodiment]
5 and 6 show a third embodiment of the present invention.
The electrostatic powder coating apparatus 3 of the present embodiment includes an object 9 to be coated, a case 10, a nozzle 20, and a needle-like discharge electrode 30 similar to the electrostatic powder coating apparatus 1 of the first embodiment described above.
In the first embodiment, the rotating counter electrode 40 is used, whereas in this embodiment, the advancing and retracting counter electrode 50 is used.

The counter electrode 50 has two electrode plates 51 and 52 that are alternately driven up and down by a lifting mechanism 53.
The electrode plates 51 and 52 are inserted through a slit or the like on the upper surface of the case 10 (where the nozzle 20 is installed). When the electrode plates 51 and 52 are lowered, the electrode plates 51 and 52 are exposed to the inside of the case 10. The cover 14 is housed inside.
In the lowered state, the electrode plates 51 and 52 are disposed in the vicinity of the surface 91 of the article 9 facing the opening 11 of the case 10 so as to face the acicular discharge electrode 30. The distance between the electrode plates 51 and 52 and the needle-like discharge electrode 30 is formed to be several times larger than the distance between the electrode plates 51 and 52 and the surface 91 of the object 9 to be coated.
When one of the electrode plates 51 and 52 is raised, the other is lowered. Accordingly, either one of the electrode plates 51 and 52 is disposed at a position facing the needle-like discharge electrode 30, and a corona discharge 31 can be formed between the needle-like discharge electrode 30.

A wiper 54 for wiping the surfaces of the electrode plates 51 and 52 is installed inside the cover 14, and the wiper 54 has a dust removing device (not shown) for collecting dust removed from the surfaces of the electrode plates 51 and 52. It is connected.
Therefore, even if the powder 8 adheres to the surface in a state where the electrode plates 51 and 52 are in the case 10, the adhered powder 8 can be removed when accommodated in the cover 14.

Also according to this embodiment, the same effect as that of the first embodiment described above can be obtained.
Furthermore, since the forward / backward type counter electrode 50 only needs to be configured to advance and retract the two electrode plates 51 and 52 alternately, the dimension in the thickness direction can be made compact.
Note that the number of electrode plates in the advancing / retracting counter electrode 50 is not limited to two, but three or more may be advanced into the case 10.

[Fourth Embodiment]
FIG. 7 shows a fourth embodiment of the present invention.
The electrostatic powder coating apparatus 4 of the present embodiment is similar to the electrostatic powder coating apparatus 3 of the third embodiment described above, the object 9, the case 10, the nozzle 20, the needle-like discharge electrode 30, and the reciprocating type. A counter electrode 50 is provided.
However, in this embodiment, the case 10 is installed upside down with respect to the third embodiment. That is, the case 10 has a cover 14 on the bottom surface side, a needle-like discharge electrode 30 and an advancing / retracting counter electrode 50 are installed in the vicinity of the bottom surface of the case 10, and the nozzle 20 is installed upward therebetween.

Also according to this embodiment, the same effect as that of the first embodiment described above can be obtained.
Furthermore, since the nozzle 20, the acicular discharge electrode 30 and the counter electrode 50 are installed near the bottom surface of the case 10, the lump of the powder 8 adhering to the acicular discharge electrode 30 and the counter electrode 50 is peeled off and dropped. However, adhesion of the article 9 and the surface 91 positioned above these to the coating film 92 can be avoided.

[Fifth Embodiment]
8 and 9 show a fifth embodiment of the present invention.
The electrostatic powder coating apparatus 5 of the present embodiment includes an object 9 to be coated, a case 10, a nozzle 20, and a needle-like discharge electrode 30 similar to the electrostatic powder coating apparatus 1 of the first embodiment described above.
In the first embodiment, the rotating counter electrode 40 is used, whereas in the present embodiment, the fixed counter electrode 60 is used.

  The counter electrode 60 is a flat electrode plate, and is disposed in the vicinity of the surface 91 of the article 9 facing the opening 11 of the case 10 so as to face the needle discharge electrode 30. Corona discharge 31 can be formed between the two. The distance between the counter electrode 60 and the acicular discharge electrode 30 is formed several times larger than the distance between the counter electrode 60 and the surface 91 of the object 9 to be coated.

  The counter electrode 60 is provided with an air brush 61 for cleaning the surface on the side facing the needle-like discharge electrode 30. The air brush 61 sprays the high-pressure air from the high-pressure air supply device 62 onto the surface of the counter electrode 60 on the side facing the needle-like discharge electrode 30 over the entire width, thereby scattering the powder 8 adhering to the surface. Can be removed.

Also according to this embodiment, the same effect as that of the first embodiment described above can be obtained.
Furthermore, since the fixed counter electrode 60 is used, there is no movable part and the mechanism can be simplified. On the other hand, since the air brush 61 for cleaning the surface of the counter electrode 60 is installed, the powder 8 does not adhere to the surface and the charging function does not deteriorate. This airbrush 61 also has no mechanical movable part, and the mechanism can be simplified.

  In this embodiment, the case 10, the nozzle 20, the needle-like discharge electrode 30, and the counter electrode 60 may be installed upside down as in the second embodiment or the fourth embodiment described above. The effects described in the embodiment or the fourth embodiment can be obtained.

[Sixth Embodiment]
10 and 11 show a sixth embodiment of the present invention.
The electrostatic powder coating apparatus 6 of the present embodiment includes an object 9 to be coated, a case 10, a nozzle 20, and a needle-like discharge electrode 30 similar to the electrostatic powder coating apparatus 1 of the first embodiment described above.
In the first embodiment, the rotating counter electrode 40 is used, but in the present embodiment, the counter electrode is omitted, and the corona discharge 31 from the acicular discharge electrode 30 is caused by the surface 91 of the article 9 to be coated. Formed directly between.

According to this embodiment, the following effects can be obtained.
In this embodiment, since the jet 81 of the powder 8 is in the direction along the surface 91 of the object 9, the powder 8 does not bounce off the object 9 and cause a reduction in coating efficiency. Further, since a baffle plate or the like is not used, coating efficiency is not reduced due to clogging.

In the present embodiment, since the jet 81 from the nozzle 20 is disposed so as to penetrate the corona discharge 31 formed between the needle-like discharge electrode 30 and the surface 91 of the object 9 to be coated, the needle-like discharge electrode 30 is It can be outside the jet 81.
For this reason, the adhesion of the powder 8 to the acicular discharge electrode 30 can be greatly reduced or prevented.
Further, the adhesion of the powder 8 to the needle-like discharge electrode 30 is suppressed, so that the lump of the powder 8 that has adhered and grown peels off and adheres to the surface 91 or the coating film 92 of the object 9 to be coated. There will be no paint defects.

In the present embodiment, the powder 8 is quantitatively supplied by the powder quantitative supply device 21, and the powder 8 quantitatively supplied to the nozzle 20 is a gas flow due to the venturi effect by the high-pressure air from the high-pressure air supply device 22. Can be sucked out, dispersed in a gas flow and sprayed to form a jet 81 of powder 8.
Thus, by using a venturi-type air nozzle as the nozzle 20 and supplying the powder 8 in a constant amount, the concentration of the powder 8 in the jet 81 of the powder 8 can be kept constant, and the coating quality is improved. be able to.

In the present embodiment, since the surface 91 to be coated of the article 9 is arranged in the vertical direction, even if there is a foreign matter such as a lump of powder 8 peeled off from the inner surface of the case 10, this foreign matter. Falls down as it is, and can be prevented from adhering to the object 9.
Moreover, since it becomes an installation of a vertical direction including the case 10, the exclusive area of an installation can be made compact.

[Modification]
The present invention is not limited to the above-described embodiments, and modifications and the like within a scope in which the object of the present invention can be achieved are included in the present invention.
In each of the embodiments described above, the nozzle 20 is a Venturi type air nozzle using high-pressure air. However, as the nozzle, it is sufficient that the powder 8 can be appropriately sprayed, and the type thereof can be arbitrarily selected.

In each of the above embodiments, the surface 9 to be coated is arranged in the vertical direction in the object 9 to be painted, but the object 9 may be sent in the horizontal direction while keeping the surface 91 in the vertical direction. The surface 91 may also be maintained horizontal. However, if the surface 91 of the article 9 is arranged in the vertical direction, adhesion of foreign matter such as a lump of powder 8 can be avoided, which is more preferable.
In addition, as the configuration of each part such as the case 10, a configuration capable of obtaining each function may be appropriately adopted.

  The present invention can be used in an electrostatic powder coating apparatus.

  DESCRIPTION OF SYMBOLS 1-6 ... Electrostatic powder coating apparatus, 10 ... Case, 11 ... Opening, 12, 13 ... Roller, 14 ... Cover, 15 ... Dust collector, 20 ... Nozzle, 21 ... Powder fixed quantity supply apparatus, 22 ... High pressure Air supply device, 30 ... acicular discharge electrode, 31 ... corona discharge, 32 ... power supply device, 40 ... rotary counter electrode, 41 ... electrode plate, 411, 412 ... area, 42 ... motor, 43 ... wiper, 44 ... Dust remover, 50 ... Advancing and retracting counter electrode, 51, 52 ... Electrode plate, 53 ... Lifting mechanism, 54 ... Wiper, 60 ... Fixed counter electrode, 61 ... Air brush, 62 ... High pressure air supply device, 8 ... Powder 81 ... Jet, 9 ... Object to be coated, 91 ... Surface, 92 ... Coating film.

Claims (9)

A nozzle for spraying powder to form a jet of the powder in a direction along the surface of the object to be coated;
A needle-like discharge electrode placed toward the object to be coated on the opposite side of the object to be coated across the jet, and a case surrounding the surface of the object to be coated, the nozzle and the needle-like discharge electrode; An electrostatic powder coating apparatus comprising: In the electrostatic powder coating apparatus according to claim 1,
The electrostatic powder coating apparatus, wherein the needle-like discharge electrode is disposed outside the jet. In the electrostatic powder coating apparatus according to claim 1 or 2,
The nozzle is an air nozzle that injects a gas for conveyance and is supplied with a fixed amount of the powder from the side of the gas flow passing through the nozzle. In the electrostatic powder coating apparatus according to any one of claims 1 to 3,
An electrostatic powder coating apparatus, wherein the object to be coated has a surface to be coated arranged in a vertical direction. In the electrostatic powder coating apparatus according to claim 4,
The electrostatic powder coating apparatus, wherein the nozzle blows up the powder upward from below the acicular discharge electrode. In the electrostatic powder coating apparatus according to any one of claims 1 to 5,
An electrostatic powder coating apparatus, wherein a counter electrode facing the acicular discharge electrode is installed between the object to be coated and the acicular discharge electrode. In the electrostatic powder coating apparatus according to claim 6,
An electrostatic powder coating apparatus, wherein an air brush for cleaning a surface of the counter electrode facing the needle-like discharge electrode is installed. In the electrostatic powder coating apparatus according to claim 6,
The counter electrode is formed in a plate shape and is rotatably supported around a rotation axis in a direction intersecting the surface, a part of the counter electrode is disposed to face the needle-like discharge electrode, and the other part of the case An electrostatic powder coating apparatus, characterized by being a rotary counter electrode disposed outside. In the electrostatic powder coating apparatus according to claim 6,
The counter electrode is formed of a plurality of electrode plates, an arbitrary one of the electrode plates is disposed to face the needle-like discharge electrode, and the other electrode plate is disposed outside the case. An electrostatic powder coating apparatus, which is a counter electrode.

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