JPH07213958A - Spray gun type electrostatic coater - Google Patents

Abstract

PURPOSE:To improve the coating efficiency by setting a high voltage generating apparatus in an external electrode holding part, and at the same time, making the separation distance between a coating nozzle and the external electrode almost equal to the distance between the external electrode and an article to be coated. CONSTITUTION:A coating nozzle 7 is installed in the tip part of a spray gun main body 6 and an earth electrode which works also as a needle valve body of a coating valve is positioned in the inside of the coating nozzle 7. A high voltage generating device 20 is built in an external electrode holding part 14. Moreover, the separation distance A of the coating nozzle 7 and an external electrode 16 and the separation distance B of the external electrode 16 and an article to be coated are set within a range from 80mm to 150mm. Consequently, the safety is improved and, at the same time, the coating efficiency is improved by making almost equal the intensity of electric fields in an electrostatic region for charging to that in an electrostatic region for transport.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a spray gun type electrostatic coating apparatus suitable for spraying water-based paints and metallic paints.

[0002]

2. Description of the Related Art Generally, paints used for electrostatic coating are roughly classified into solvent-based paints (oil-based paints) having a relatively large electric resistance and water-based paints (water-based paints) having a relatively small electric resistance value. Further, there are metallic paints in which metal powder is dispersed in these solvent-based paints and water-based paints, and these metallic paints have relatively small electric resistance values like water-based paints. As described above, since the paint has different resistance values depending on its type, the method of applying the high voltage also differs depending on the type of paint.

That is, from the viewpoint of danger prevention, the paint supply pipe,
Although paint tanks, color change valve devices, etc. are used by connecting them to earth, solvent-based paints have a relatively large resistance.
Even if a high voltage is directly applied to the center electrode of the spray gun main body from a high voltage generator provided outside, the spray gun main body does not reach the ground potential via the paint supply pipe line.
Therefore, the electrostatic coating device used for the solvent-based paint is designed so that a high voltage is directly applied to the spray gun body to directly charge the paint particles.

On the other hand, since water-based paints and metallic paints have a small electric resistance value, when a high voltage is directly applied to the center electrode of the spray gun body, the spray gun body is grounded through the paint in the paint supply pipe line. Shorted to the potential,
The paint particles cannot be charged.

Therefore, in the case of water-based paint or metallic paint, an external electrode is provided radially outside the spray gun body, and a high voltage (for example, − An external electrode type spray gun electrostatic coating device is used in which the central electrode (earth electrode) of the spray gun body is connected to the ground while applying 40 to -90 kV).

Here, the external electrode type spray gun type electrostatic coating apparatus will be described. By applying a high voltage to the external electrode, a space between the ground electrode and the external electrode,
Between the external electrode and the article to be coated, an electrostatic field for charging and an electrostatic field for transport are formed by the lines of electric force. Further, each zone is an ionization zone because a high voltage of −90 kV is applied to the external electrode. Then, the paint particles sprayed from the paint nozzle are indirectly charged in the electrostatic field for charging, and the charged paint particles are transported toward the object to be coated in the electrostatic field area for transportation, and are then applied to the object to be coated. It is applied.

As described above, even the water-based paint and the metallic paint having a relatively small resistance value are coated by using the external electrode type spray gun type electrostatic coating device.

[0008]

By the way, in the above-mentioned external electrode type spray gun type electrostatic coating apparatus according to the prior art, the charge of the paint is improved by bringing the ionization zone close to the paint spray port. From an idea,
The distance between the paint nozzle (external electrode) and the object to be coated is set to approximately 1: 4 with respect to the distance between the paint nozzle (ground electrode) and the external electrode. Therefore, the lines of electric force (electric field strength) in the electrostatic field region for charging tend to be strong, and the lines of electric force (electric field strength) in the electrostatic field region for transport tend to be weak.

Of the paint particles charged in the electrostatic field for charging, paint particles that could not be applied to the object to be coated are sprays having a ground electrode along the lines of electric force in the electrostatic field for charging. There is a problem that the paint particles that are returned to the gun body and adhere to the spray gun body and the like, and the uncharged paint particles adhere to the external electrode holding portion and the like of the external electrode.

Further, if the coating is continued with the coating adhered to the external electrode holder and the spray gun body, the coating adherence is increased at an accelerated rate (so-called, so-called
There is a problem in that the quality of the finish of the coating is deteriorated and the reliability of the coating machine is significantly impaired.

On the other hand, a high voltage generator for applying a high voltage to the external electrode is installed outside the coating booth, and the high voltage generator and the external electrode are connected via a long high voltage cable. There are many stray capacitances in high voltage cables. Therefore, when a high voltage is applied to the external electrode, the high voltage cable is charged with electric charges and a large amount of electrostatic energy is accumulated in the high voltage cable. Then, when the worker accidentally contacts the external electrode or the external electrode holding portion after the application to the external electrode is stopped, there is a risk that the charge charged through the worker is discharged and the worker is electrocuted. .

The present invention has been made in view of the above-mentioned problems of the prior art, and a first object of the present invention is to incorporate a high voltage generator in the external electrode holder and to provide the high voltage generator and the external electrode. The object of the present invention is to provide a spray gun type electrostatic coating device capable of improving safety by bringing the two closer together.
A second object of the present invention is to set the positional relationship between the external electrode and the paint nozzle to reduce dirt on the spray gun main body and the external electrode rod and improve the coating efficiency. To provide an electric coating device.

[0013]

According to a first aspect of the present invention, there is provided a spray gun type electrostatic coating device, which comprises a spray gun main body and a tip end side of the spray gun main body. A paint nozzle for ejecting paint toward the ground electrode, a ground electrode held on the ground potential and provided on the spray gun body so that the tip side is located at the paint spray port of the paint nozzle, and an outer peripheral side of the spray gun body. An external electrode holding portion that is provided so as to project forward of the ground electrode, an external electrode that is provided on the tip side of the external electrode holding portion, and to apply a high voltage to the external electrode. , A high voltage generator built in at the base end side of the external electrode holder.

According to a second aspect of the present invention, there is provided a spray gun type electrostatic coating device, wherein the spray gun main body and the spray gun main body are provided at the tip end side of the spray gun main body and apply the paint from the paint spraying port toward the article to be coated. A spraying paint nozzle, a ground electrode which is held at a ground potential, and which is provided on the spray gun body so that its tip end is located at the paint spraying port of the paint nozzle; and a ground electrode provided on the outer peripheral side of the spray gun body. An external electrode holder arranged so as to project forward of the ground electrode, an external electrode provided on the tip side of the external electrode holder, and a high voltage generator for applying a high voltage to the external electrode. And the radial distance between the paint nozzle and the external electrode is set in the range of 80 to 150 mm, and the axial clearance is set in the range of 80 to 150 mm.

Further, it is preferable that the spray gun body and the external electrode holding portion of the external electrode are made of an insulating resin material.

Further, the earth electrode is constituted by a needle valve body of a paint valve for closing the paint spraying port of the paint nozzle, and the needle valve body can be formed of a conductive material.

[0017]

According to the structure of claim 1, the length of the high-voltage cable connecting the high-voltage generator and the external electrode can be shortened, the stray capacitance by the cable can be reduced, and the high voltage is applied to the external electrode. The electrostatic energy charged in the high-voltage cable during charging can be reduced.

According to the structure of claim 2, the electric field intensities of the electrostatic field for charging and the electrostatic field for transportation of the paint nozzle and the external electrode are brought close to each other, and the electrostatic field for charging and the electrostatic field for transportation are brought close to each other. Can be well balanced, and the paint sprayed from the paint nozzle can be prevented from adhering to the spray gun body or the external electrode holding portion.

According to the third aspect of the present invention, by forming the spray gun body and the external electrode holding portion with the insulating resin material, it is possible to reduce high voltage discharge from the spray gun body and the external electrode holding portion to the outside.

Further, according to the structure of claim 4, the needle valve body of the paint valve for closing the paint spraying port of the paint nozzle is made of a conductive material, and the needle valve body is used as a ground electrode to be charged. The paint particles are conveyed along the lines of electric force formed from the external electrode toward the earth electrode, and the spray gun main body can be prevented from being contaminated with the returned paint.

[0021]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT An embodiment of the present invention will be described below with reference to FIGS.

In FIG. 1, reference numeral 1 denotes a spray gun type electrostatic coating apparatus according to the present embodiment.
Is a mounting portion 2 for fixing to a reciprocator (not shown) or the like.
And a coating device 4 fixed to the valve device mounting portion 3, and a side surface of the valve device mounting portion 3 having a paint valve 21, 22 described later and a drain valve 23 and the like built therein. Is stuck,
The external electrode section 5 is arranged substantially parallel to the outer peripheral side of the coating machine 4.

Here, the construction of the coating machine 4 will be described with reference to FIG.

In FIG. 2, reference numeral 6 denotes a spray gun body, which is made of polytetrafluoroethylene or polyethylene terephthalate (hereinafter referred to as "PET") as an insulating resin material and formed into a long tubular shape. A nozzle accommodating portion 6A, which is a tapered concave portion for accommodating a paint nozzle 7 described later, is formed on the tip end side of the spray gun main body 6, and the base end side is fixed to the valve device mounting portion 3.

Reference numeral 7 denotes a paint nozzle which is screwed to the center of the tip of the spray gun body 6 and is formed in a stepped cylindrical shape made of polytetrafluoroethylene, PET or the like, and the paint nozzle 7 is located at the central portion. And a mist formed on the outer peripheral side of the guide cylinder portion 7A, in which the needle valve body (ground electrode 13) of the front side paint valve 21 is movably provided and is formed to extend in the axial direction. The guide air portion 7B is generally constituted by a liquefied air passage 7B, and a paint spray port 7C is integrally formed on the tip end side of the guide cylinder portion 7A.

Reference numeral 8 denotes an air nozzle which is provided so as to cover the tip side of the paint nozzle 7 and is fixed to the tip side of the spray gun body 6 via a retainer ring 9, and the tip outer peripheral side of the air nozzle 8 is A pair of horn portions 8A, 8A are provided facing each other. Further, a plurality of atomized air ejection ports 8B, 8B, ... (2
(Only one is shown) is formed so as to surround the paint spraying port 7C of the paint nozzle 7, and a plurality of pattern air jets 8C, 8C, ... (Only two are shown) are formed in each horn portion 8A. . Then, the air nozzle 8 ejects atomized air from each atomized air ejection port 8B, whereby the paint nozzle 7
The spray of paint sprayed from the paint spray port 7C of No. 1 is promoted, and each pattern air jet port 8C is sprayed to the sprayed paint.
The spray pattern of paint is formed into an elliptical or oval shape by spraying pattern air from the.

Reference numeral 10 denotes a paint supply passage formed between the ground electrode 13 and the spray gun body 6, and a rear paint valve 22 and a front paint valve 21 which will be described later are connected in the middle of the paint supply passage 10. Has been done. Reference numeral 11 denotes a paint discharge passage which is bored in the axial direction of the spray gun main body 6 and connects the paint supply passage 10 with the outside.
A drain valve 23 is connected in the middle of 1. Also. 12
Shows an atomizing air supply passage provided in the spray gun main body 6 in the axial direction.

Reference numeral 13 denotes a ground electrode, and the ground electrode 1
3 is configured as a needle valve body of the front side paint valve 21, and the tip 13A is seated in the paint spray port 7C of the paint nozzle 7 so as to have a length that does not project from the paint spray port 7C. It is formed of a material (for example, a conductive metal material, a conductive resin material, etc.). When the front side paint valve 21 is opened, the tip portion 13A of the ground electrode 13 moves to the base end side, the paint spray port 7C is opened, and the paint in the paint supply passage 10 is sprayed to the paint spray port 7C. It is supposed to be sprayed from.

Next, the structure of the external electrode portion 5 will be described with reference to FIG.

In FIG. 3, 14 is a spray gun body 6
Shows an external electrode holding portion serving as an external electrode holding rod provided on the outer peripheral side of the external electrode holding portion 14. The external electrode holding portion 14 is made of an insulating resin material such as polytetrafluoroethylene or PET, and has a large outer diameter on the proximal end side. The portion 14A is formed in a rod shape such that the tip side is a small diameter portion 14B and a portion between the large diameter portion 14A and the small diameter portion 14B is a tapered portion 14C. Further, the inner diameter has a circuit housing portion 14D for housing a high voltage generator 20 described later on the proximal end side, and a resistor housing portion 14E for housing the high resistance body 17 on the distal end side. Is a lead wire insertion hole 14 into which a lead wire 15 for connecting an external controller (not shown) and the high voltage generator 20 is inserted.
F is drilled, and the tip portion 16A of the external electrode 16 is provided on the tip side.
Is formed with an electrode insertion hole 14G projecting therefrom. In addition,
The lead wire 15 outputs a high voltage application signal from a signal generator (not shown) provided outside to the high voltage generator 20, and the high voltage application signal is a low voltage AC voltage.

Reference numeral 16 denotes an external electrode, and a tip portion 16A of the external electrode 16 is located at a position of a space A in the radial direction and a space B in the axial direction from the paint nozzle 7 of the coating machine 4, as shown in FIG. It is set so that it protrudes from the electrode insertion hole 14G of the external electrode holding portion 14.

Reference numeral 17 denotes a high resistance element accommodated in the resistance element accommodating portion 14E. The external electrode 16 is fixed to the tip end side of the high resistance element 17 and a conductive spring 18 is attached to the base end side. The high voltage generator 20 is connected via a connection cable 19 or the like. The high resistance body 17 has a resistance value of 20 MΩ, for example, and is adapted to adjust the high voltage current value generated from the high voltage generator 20.

Reference numeral 20 denotes a high voltage generator housed in the circuit housing portion 14D. As shown in FIG. 4, the high voltage generator 20 has a plurality of capacitors 20A and diodes 20A.
A multi-stage voltage doubler rectifier circuit (Cockcroft circuit) including B and its outer periphery is molded by a resin mold portion 20C made of an insulating resin.

Further, each valve device provided in the valve device mounting portion 3 will be described with reference to FIG.

In FIG. 4, reference numerals 21 and 22 denote a front-side paint valve and a rear-side paint valve, respectively, which are located in the valve device mounting portion 3 and are provided in the middle of the paint supply passage 10, respectively. Is a 2-port 2-position spring return type air switching valve that is switched by supplying and discharging compressed air FA, RA. And both paint valves 2
When the valves 1 and 22 are opened, the paint from the color change valve device (not shown) arranged outside is supplied toward the paint nozzle 7.

As shown in FIG. 2, the needle valve element of the front side paint valve 21 shares the ground electrode 13 extending toward the axial tip of the spray gun body 6, and the needle valve element (earth electrode 13). The tip 13A of () closes the paint spray port 7C of the paint nozzle 7. As a result, when the compressed air FA is supplied to the front paint valve 21, the needle valve body (earth electrode 13) moves to the axial base end side of the spray gun body 6 and the paint spray port 7C.
Is opened and the paint in the paint supply passage 10 is moved to the paint nozzle 7
Gushes in front of.

Reference numeral 23 denotes a drain valve provided inside the valve device mounting portion 3. The drain valve 23 is the paint valve 21, 2.
2 and an external drain tank (not shown) are connected in the middle of a paint discharge passage 11, and the paint valve 2
Similar to 1 and 22, it is configured as a 2-port 2-position spring return type air switching valve that is switched by supplying and discharging compressed air DA. By opening the drain valve 23, the paint or cleaning liquid in the paint supply passage 10 is discharged to the drain tank.

Reference numeral 24 is a pattern air passage for supplying air to each horn portion 8A of the air nozzle 8, and 25 is an exhaust air passage.

The spray gun type electrostatic coating apparatus 1 according to this embodiment has the above-mentioned structure, and its basic operation is almost the same as that of the prior art.

That is, the paint discharged from the color change valve device is
It flows into the paint supply passage 10 of the spray gun body 6.
Next, by supplying compressed air RA, FA to the rear side paint valve 22 and the front side paint valve 21, each valve body is opened, and the ground electrode 13 is also connected to each paint spray port 7 of the paint nozzle 7.
The paint, which is separated from C and is filled in the guide cylinder portion 7A, is provided at the tip end side in the axial direction of the spray gun main body 6,
It is sprayed toward the article to be coated 26 (see FIG. 5) connected to the ground. At this time, the spray pattern of the paint particles is formed into an elliptical or oval shape by the pattern air ejected from each atomizing air ejection port 8B of the air nozzle 8. The article to be coated 26 is moved at a constant speed by a conveyor (not shown).

On the other hand, the earth electrode 1 provided in the spray gun body 6 is located inside the paint spray port 7C of the paint nozzle 7.
3 is short-circuited to the ground, and the external electrode 16 located on the outer periphery of the spray gun body 6 is connected to the high voltage generator 20. Here, the high voltage (−9
0 kV) is applied to the external electrode to form a charging electrostatic field zone between the ground electrode 13 and the external electrode 16, and a transport electrostatic field zone between the external electrode 16 and the object to be coated 26. A zone is formed. Then, as described above, the paint particles sprayed from the paint nozzle 7 are indirectly charged in the electrostatic field for charging, and the charged paint particles are transported toward the object to be coated 26 in the electrostatic field for transport. And is applied to the article 26 to be coated.

In the present embodiment, however, by incorporating the high voltage generator 20 in the external electrode holding portion 14 of the external electrode 16, the high voltage generator 20 and the external electrode 16 are incorporated.
Connection cable 1 for connecting with the high-resistance element 17 connected to
The length of 9 can be shortened, and the stray capacitance of the connection cable 19 and the connection spring 18 can be reduced.

As a result, in the coating process, when a high voltage is applied to the external electrode 16, the electrostatic energy of the electric charge charged in the connection cable 19 can be made extremely small, and the discharge current after the coating can be made small. it can. As a result, even if the worker accidentally contacts the external electrode 16 or the external electrode holder 14 after the application of the high voltage to the external electrode 16 is stopped, the electric charge discharged through the worker is extremely small and The danger of electric shock to people is eliminated.

Further, the applicant of the present invention has found that the space A between the paint nozzle 7 and the external electrode 16 in the radial direction and the space B in the axial direction between the paint nozzle 7 and the external electrode 16.
As a result of an earnest experiment on the relationship with, the characteristic diagram shown in FIG. 6 was obtained. In this experiment, the spray gun type electrostatic coating apparatus 1 according to this example was used, and the distance C (see FIG. 5) between the paint nozzle 7 and the article to be coated 26 was set to 300 mm.

The experiment was conducted under the following conditions.

Discharge amount of paint: 250 cc / mi
n Paint used: Water-based solid (red) Atomizing air: 1.5 kg / cm ² (gun source pressure) Pattern air: 2.0 kg / cm ² (gun source pressure) Reciprocating linear velocity: 65 m / min Conveyor velocity: 1. 8m / min External electrode supply voltage: -80kV

FIG. 6 shows the result of coating under these conditions.

Here, FIG. 6 shows the distance A in the radial direction on the horizontal axis.
Is taken, and the vertical dimension is the distance B in the axial direction, and the coating efficiency (coating efficiency = coating amount of coating material onto coating object 26 / coating discharge amount) at the position of each external electrode 16 is represented by a number. It is shown.

From the results shown in FIG. 6, if the area where the coating efficiency is about 57% (preferably 60%) or more is surrounded, the range of the optimum area G surrounded by the thick line is obtained. On the other hand, the hatched area in FIG. 6 is the area where the paint stains have occurred on the external electrode holding portion 14 and the like (hereinafter referred to as “dirt area D”).

Here, in the radial separation dimension A,
It can be seen that when it is 80 mm or less, it is not suitable because it is in the dirt region D, and when the separation dimension A is large, the lines of electric force in the electrostatic field area for charging are weakened and the coating efficiency is lowered. Accordingly, it is recognized that the coating efficiency is improved when the radial separation dimension A is 80 to 150 mm.

On the other hand, in the axial separation dimension B, 8
If the thickness is 0 mm or less, the speed of the paint particles sprayed from the paint nozzle 7 is high, so that not only the paint particles cannot be reliably charged in the electrostatic field for charging, but also the electric field strength in the electrostatic field for transport is weakened. Moreover, it is not possible to obtain high coating efficiency. On the other hand, it is understood that when the separation dimension B becomes large, the lines of electric force in the electrostatic field for charging are weakened, the paint particles cannot be reliably charged, and the coating efficiency cannot be improved. Accordingly, it is recognized that the coating efficiency becomes good when the axial separation dimension B is 80 to 150 mm.

The coating efficiency under the above conditions when no voltage is applied to the external electrode 16 is 34.6%.

As described above, in the spray gun type electrostatic coating apparatus 1 according to this embodiment, the paint nozzle 7 and the object to be coated 2 are
6 is set to 300 mm, the positional relationship between the paint nozzle 7 and the external electrode 16 is 80 to 150 for the radial distance A and the axial distance B, respectively.
By setting the distance in the range of mm, the relationship between the separation dimension A between the paint nozzle 7 and the external electrode 16 and the separation dimension B between the external electrode 16 and the object to be coated 26 becomes approximately 1: 1 to 1: 2. can do. As a result, the strength (electric field strength) of the lines of electric force in the electrostatic field area for charging can be made equal to the strength (electric field strength) of the lines of electric force in the transfer electrostatic field area.
As a result, the coating efficiency can be improved and
The paint stain on the external electrode portion 5 can be reduced.

As a result of the above data, in the spray gun type electrostatic coating apparatus 1 in the embodiment,
The distance A between the paint nozzle 7 and the external electrode 16 in the radial direction and the distance B in the axial direction are each 100 mm, and the distance C between the paint nozzle 7 and the object to be coated 26 is set to 300 mm.

On the other hand, by improving the coating efficiency, it is possible to reduce the amount of non-coated charged coating particles, reduce the stain on the spray gun main body 6 of the coating machine 4, etc. So-called dripping can be prevented, the finish quality of the coating can be improved, and the reliability of the coating apparatus 1 can be improved.

Further, the spray gun body 6 and the external electrode 16
Since the external electrode holding portion 14 is formed of an insulating resin material such as polytetrafluoroethylene or PET, it is possible to electrically insulate the ground electrode 13 and the external electrode 16 reliably and reduce paint stains.

Further, since the ground electrode 13 is provided on the spray gun body 6 so as not to project from the paint spray port 7C of the paint nozzle 7, it is provided between the tip portion 13A of the ground electrode 13 and the tip portion 16A of the external electrode 16. Cannot form an electric force line in a straight line state, so that an insulation distance can be secured, a suction force for charged paint particles can be mitigated, and paint stains near the ground electrode 13 can be prevented. .

In the above embodiment, the atomizer air spray gun was used as the coating machine 4 by way of example.
It may be applied to a hydraulic atomization type spray gun using a lip-shaped nozzle tip, and in this case, the liquid atomization is performed by discharging high-pressure paint from the nozzle tip.

[0059]

The spray gun type electrostatic coating device according to the present invention is as described above in detail, and the base end of the external electrode holding portion for holding the external electrode provided on the outer peripheral side of the spray gun body. Since the high voltage generator formed by the multiple voltage circuit is built in the side, the length of the connecting cable connecting the high voltage generator and the external electrode can be shortened, and the stray capacitance can be reduced. Can be made smaller.
As a result, when a high voltage is applied to the external electrode, the electrostatic energy due to the electric charge stored in the connection cable can be reduced, and electric shock after the application is stopped can be reliably prevented.

Further, since the space between the paint nozzle and the external electrode in the radial direction and the axial direction is set within the range of 80 to 150 mm, the electric field strength of the electrostatic field for charging and the electric field strength of the electrostatic field for transport are set. Close to each other to improve the balance between the electrostatic field area for charging and the electrostatic field area for transport, which reduces the adhesion of the paint sprayed from the paint nozzle to the spray gun body and the external electrode holding part. It is possible to improve the coating efficiency on the coating material.

Further, since the spray gun body and the external electrode holding portion of the external electrode are made of the insulating resin material, the ground electrode and the external electrode can be electrically and reliably insulated, and the paint stain can be reduced.

Further, since the needle valve element of the paint valve is made of a conductive material and is also used as the ground electrode, the ground electrode and the external electrode cannot be connected by a straight line distance, and the insulation distance is ensured. Therefore, the performance of the coating machine can be surely improved, and the life of the coating machine can be extended.

[Brief description of drawings]

FIG. 1 is a side view showing a spray gun type electrostatic coating apparatus according to an embodiment of the present invention.

FIG. 2 is a longitudinal sectional view of an essential part showing the vicinity of a paint nozzle in FIG.

FIG. 3 is a vertical sectional view showing an external electrode holding portion in FIG.

FIG. 4 is a configuration diagram showing a paint system and an electric system of the spray gun type electrostatic coating apparatus according to the present embodiment.

FIG. 5 is an explanatory diagram showing a radial separation distance from a paint nozzle to an external electrode, an axial separation distance, and a separation distance from a paint nozzle to an object to be coated in the coating apparatus according to the present embodiment.

FIG. 6 is a characteristic diagram showing numerically the coating efficiency at each position when the position of the external electrode with respect to the paint nozzle is changed by changing the radial separation dimension and the axial separation dimension. .

[Explanation of symbols]

 1 Spray Gun Type Electrostatic Coating Device 4 Coating Machine 5 External Electrode Section 6 Spray Gun Main Body 7 Paint Nozzle 8 Air Nozzle 13 Earth Electrode 14 External Electrode Holding Section 16 External Electrode 20 High Voltage Generator

Claims (4)

[Claims] 1. A spray gun main body, a paint nozzle which is provided at a tip end side of the spray gun main body, and which sprays paint from a paint spray port toward an object to be coated, and is held at a ground potential,
A grounding electrode provided on the spray gun body so that the tip side is located at the paint spraying port of the paint nozzle, and an outer circumference side of the spray gun body, which is provided so as to project forward from the grounding electrode. External electrode holding part,
A spray composed of an external electrode provided on the tip side of the external electrode holding part and a high voltage generator built in at the base end side of the external electrode holding part for applying a high voltage to the external electrode. Gun type electrostatic coating device. 2. A spray gun main body, a paint nozzle which is provided at a tip end side of the spray gun main body, and which sprays paint from a paint spray port toward an object to be coated, and is held at a ground potential,
A ground electrode provided on the spray gun main body so that the tip side is located at the paint spraying port of the paint nozzle, and provided on the outer peripheral side of the spray gun main body so as to project forward from the ground electrode. External electrode holding part,
An external electrode provided on the tip side of the external electrode holder, and a high voltage generator for applying a high voltage to the external electrode,
The distance between the paint nozzle and the external electrode in the radial direction is set to 80.
~ 150 mm range, and the axial separation dimension is 80 ~
Spray gun type electrostatic coating device that is set in the range of 150 mm. 3. The spray gun type electrostatic coating device according to claim 1, wherein the spray gun body and the external electrode holding portion of the external electrode are formed of an insulating resin material. 4. The ground electrode is constituted by a needle valve body of a paint valve for closing a paint spraying port of a paint nozzle, and the needle valve body is made of a conductive material. Spray gun type electrostatic coating device.