JP2004148240A - Electrostatic coating gun and external electrification electrode therefor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve safety and handleability by constituting an external electrode which maintains a high voltage by adequately limiting the electric current to a paint to be supplied in such a manner that the electrode is made attachable and detachable by maintaining the insulation from an atomizer which is a ground potential side in the case of electrostatic coating of the conductive paint. <P>SOLUTION: On the outer side of a spray gun having the atomizer at its tip, an external electrode body which consists of an insulation material over the entire part and has the electrode projected at its tip is freely attachably and detachably provided on a high-voltage output part of the gun body so as to be made easily exchangeable. The attaching and detaching section is set so that a distance at which a juncture with a high-voltage output end through a current-limiting high resistance reaches an outside surface exposure section can be sufficiently taken. The above section can be made to maintain safety and can be made shorter by providing the same with a turning over section. Further, the electrode body itself is simplified and is made exchangeable with a single action of exchange and in addition, the electrode body is configured of a flexible and elastic material for the purpose of failure prevention. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a spray gun for electrostatic coating which is excellent in coating efficiency, safety and workability, particularly when electrostatically coating highly conductive paints such as water-based paints and metallic paints. .
[0002]
2. Description of the Related Art Electrostatic coating is widely used as a coating method for charging sprayed paint particles with high voltage static electricity and improving the coating efficiency by an electric field formed on an object to be coated from an electrostatic spray gun. I have. Paints used for such electrostatic coating are roughly classified into solvent type paints having a large electric resistance value and high conductive paints such as water-based or metallic paints having a low electric resistance value in relation to the effect. The coating method and equipment are very different.
[0003]
That is, the use of solvent-based paints containing volatile organic compounds has been demanded to be reduced due to recent environmental problems, and a shift to water-based paints has been required. However, when an attempt is made to increase the electrostatic coating effect by directly charging the sprayed paint, in the case of a water-based paint, a high voltage that is charged in a usual apparatus flows through the paint to a grounded paint supply source, and the electrostatic force is reduced. Not only is the effect not obtained, but also a danger of high voltage flowing in the paint supply system.
[0004]
For this reason, a method and apparatus for insulating the paint supply system from the ground side and performing electrostatic coating while maintaining a high voltage have been used. However, due to the enormous amount of charge in the paint supply system, an increase in danger is unavoidable. Further, in order to increase the industrial efficiency by performing continuous coating work, paint supply as disclosed in JP-A-6-198228 is required. It is necessary to use the device, and it is necessary to introduce a large-scale device, and there are also problems in use precaution and maintenance.
[0005] Due to these problems, electrostatic coating of water-based paints and metallic paints has not spread widely and has caused delays in environmental measures. On the other hand, the paint particles passing through the area ionized by the discharge from the electrode installed outside the spray area without being directly charged with the paint are charged and placed on the line of electric force (electric field) toward the work to be painted, 2. Description of the Related Art An electrostatic coating machine using an external electrode to be coated on a substrate is known.
As one of the devices, an electrostatic coating device as disclosed in Japanese Patent No. 2770079 or Japanese Patent Application Laid-Open No. 7-213958 has been proposed as a device which is integrated with a spray gun and cooperates therewith.
[0006]
An external electrode type electrostatic coating spray gun applies a high voltage to an external electrode installed at a position outside the spray paint area by the spray gun, thereby discharging to the ground potential side of the object to be coated etc. to generate an electric field. It forms and charges the fine particles of the paint passing therethrough and places it on an electric field formed toward the object to be coated to promote coating. However, the effect of charging the paint particles passing through the discharge area is lower than that of the direct charging method described above, and a sufficient electrostatic effect has not been obtained.
[0007]
In general, as a spray gun for electrostatic coating that can obtain the effects of commercial use, in the case of a direct charging type used mainly for solvent-based coatings, the charging voltage to the electrode is about -30 kV to about -70 kV, and the potential difference is The effect is obtained as much as possible, but it is required to be as low as possible in view of the increased risk of spark discharge or electric shock discharge due to high voltage and the withstand voltage strength of the device. Therefore, it is often used at around -50 kV. On the other hand, in the case of the external electrode system, it is common to charge with a higher potential difference.
[0008]
The external charging method requires a higher voltage in order to obtain a practical effect, compared to a method in which a charging electrode is placed directly at the center of the paint spray to efficiently charge, and the position of the charging electrode is substantially equal to the ground potential. It is installed in front of the spraying device in order to prevent dangerous discharge to the ejection port of the spray paint on the side and voltage reduction of the charging electrode due to the discharge.
Usually, in the case of a commercial spray gun, it is also called 80 mm to 150 mm, and has a configuration in which it protrudes greatly. For this reason, many have been used as automatic spray guns that are driven by being attached to an automatic coating device. In other words, as a hand-held spray gun, the charging electrode protrudes greatly forward and is placed off the center axis of the spray to prevent its function from deteriorating due to spray paint, so it is large and difficult to operate. It became a spray gun, increasing the burden on workers.
[0009]
Although there are proposals for hand-held electrostatic spray guns, there are many problems such as the fact that the electrode protruding at the tip at a practical level makes the operability worse, and there is the danger that the electrode may hit the product during operation and be damaged. It remained and hindered the spread of the proposed one. Also, there is a big difference between the direct charging of the paint and the charging by the discharge of the electrode provided outside.It is required to improve the safety by using higher voltage and to improve the coating efficiency by effective charging. Is required.
[0010]
[Problems to be solved by the invention]
As described above, in the case of the external charging type, the charging effect is not sufficiently obtained, so it is necessary to consider the use of higher voltage and the danger against it, and to consider the dielectric breakdown due to high voltage, and as a spray gun There have been many problems in downsizing the device and putting it into practical use as a hand-held spray gun.
[0011]
A fundamental problem to be solved by the present invention is to improve the operability of an electrostatic spray gun having an externally charged electrode and to protect workers by ensuring safety. Furthermore, the size of the electrostatic spray gun itself has been reduced, ensuring reliability and improving coating efficiency as a device that can be used for hand-held spray guns. It is to plan. Therefore, it is very important to reduce the size of the electrode body protruding to the outside and to facilitate the handling.
[0012]
In addition to electrostatic spraying, spray guns for painting are used for mass production painting on automated lines in factories, but hand-held spray guns used by workers are used for spray coating. This type of spray gun is often used in the process of determining final quality, and poses a problem in safety and operability. In this case, the handling and operability of the spray gun is not only economical to improve coating efficiency, but also leads to improvement in work efficiency, improvement and stability of coating quality, and an overall and long-term improvement effect. Is a very important factor.
[0013]
In this regard, conventional spray guns for electrostatic coating are premised on automatic spray guns that are attached to automatic equipment, etc., and are strictly designed for handling, operability and strict safety measures against danger to workers directly. There is room for improvement. In order to arrange the external electrode in the area of the spray gun normally used, it is important that the electrode is lightweight because it needs to be located far away from the spray nozzle, but it is necessary to combine the necessary elements However, the problems of handling and weight reduction which are most necessary for the operator using the method have not been solved. In addition, a high voltage generator that charges the electrodes is provided integrally with the spray gun to release the operator from the weight of the high voltage cable, eliminating the danger from the electrodes charged to the high voltage protruding forward from the spray nozzle. This requires a spray gun for electrostatic coating that has a high overall practical value.
[0014]
On the other hand, if painting is continued with the paint adhered to the external electrodes and electrode holders, the accumulated paint particles will increase the accumulation and cause the paint to sag, reducing the finish quality of the paint and reducing the reliability of the coating machine. There is a problem of spoiling. In addition, when the diluent in the paint does not dissolve easily, as in the case of a water-based paint, the solid content acts as an insulator, and the effect as an electrode is greatly reduced.
Therefore, it is required to be able to withstand long-term use and to be able to return to a normal state immediately when the function is reduced or disabled.
[0015]
The present invention has been made in view of the above-described problems and demands of the related art, and is capable of being used safely by an operator, being easy to use, and improving productivity and economy in the main range of electrostatic coating used. An effect is obtained, and as a result, a spray gun for electrostatic coating can be obtained which can contribute to the widespread use of water-based coatings which greatly improves environmental problems.
[0016]
[Means for Solving the Problems]
In the present invention, a spray gun for electrostatic coating is provided with a high-voltage generator and an atomizing device, which is separated from the path of the paint supplied to the atomizing device while maintaining electrical insulation, and is provided outside the atomizing device. For a spray gun that has an externally charged electrode protruding in front of the atomizing device, the externally charged electrode is attached to and detached from the electrode connection part provided outside the handheld spray gun with a conductive handle behind the atomizing device. Make it possible. As a result, even if the external electrodes become dirty and their functions deteriorate, they can be easily replaced and returned to the normal state. The same applies to the case where the player accidentally crashes during operation.
[0017]
The electrode connection is provided between the atomizing device and the rear handle so as not to impair the operability of the miniaturized spray gun of the externally charged electrode. From another aspect of safety, by providing a second limiting resistor on the electrode side with respect to the first high resistance provided on the high voltage output side of the electrical junction, the electrode side on which the high voltage is charged is provided. Capacitance can be reduced.
[0018]
The detachable part is the distance between the electrical junction with the high-voltage output part and the exposed end of the outer surface of the detachable part fitting surface, the distance that can prevent creeping discharge. Is prevented from creeping discharge to the ground potential side of the tip of the spray gun or the rear handle due to the influence of the surface approaching or contamination of the surface.
[0019]
As a means to effectively prevent creeping discharge when the connection part itself is shortened and the barrel part is shortened, a folded part is provided between the electrical joint part and the outer surface exposed end of the attachment / detachment part fitting surface. Is adopted. As a result, insulation between the electrode connection portion having a high potential and the outer surface is maintained, and the length of the detachable portion of the gun body and the length of the detachable electrode body can be shortened, thereby facilitating handling.
[0020]
The folded portion has a shape in which a plurality of concentric deep grooves are alternately fitted, so that the creeping distance can be increased and creeping discharge to the outer surface portion can be prevented. In addition, it is possible to shorten the external electrode itself and improve the handling.
[0021]
Further, a feature of the present invention is that the external electrode is exposed at the tip and the electrode body composed of an insulator is formed of a flexible or elastic material, thereby protecting the electrode body from breakage and deformation due to unexpected collision or the like. It absorbs shocks and prevents temporary damage by responding to temporary deformation, improving durability. If the electrode body is damaged due to a greater impact, do not cause damage to the mounting part provided on the spray gun side, so that the electrode body comes off or a part of it is damaged and minimal damage is required. It is also necessary to provide a weak portion in a part of the electrode body. As a result, damage to the entire apparatus can be minimized, and it is possible to return to a normal state by simply replacing the electrode body.
Other detailed features will be described in the embodiments.
[0022]
DESCRIPTION OF THE PREFERRED EMBODIMENTS
An embodiment of the present invention will be described below with reference to FIGS.
Reference numeral 1 denotes an externally charged electrostatic spray gun according to the present embodiment. The spray gun 1 is a hand-held type and is operated by a handle 2 and a trigger 3. The barrel 4 controls the paint sprayed from the atomizing device 5 provided at the tip, and controls the input and output of a low-voltage power supply to be supplied to the high-voltage generator 6 disposed above the barrel 4, thereby controlling the spraying. The high voltage applied to the tip electrode 71 of the external electrode 7 provided outside the gun 1 is controlled.
[0023]
In this embodiment, the atomizing device 5 is an air spray gun for atomizing the paint with compressed air. An air cap 51 is provided around a paint nozzle 52, and a desired spray pattern is applied to the air cap 51. The coating of the object to be coated is performed. These structures adopt a widely known structure of a spray gun, but are formed of an electrically insulating material including the barrel 4 in electrostatic coating. In the case of a spray gun in which a water-based or highly conductive paint is used in the present invention and a charged electrode is provided outside, the paint path is connected to the ground side potential, so that the needle valve 53 in the paint nozzle 52 is made of metal, Is electrically connected to the handle 2. The handle is electrically conductive, as is the case with conventional electrostatic spray guns, and in this embodiment, a semi-conductive resin is used to provide a ground potential for manual operation by an operator. I have to.
[0024]
As shown in FIG. 2, the high-voltage generator 6 includes a low-frequency transformer 61, a Cockcroft-Walton multistage voltage doubler rectifier circuit 62, and a cartridge 64 in which a protective high-resistance 63 is cast with an insulating resin. The cartridge 64 maintains the electrical insulation strength except that the input terminal 65 is exposed on the low voltage supply side and the output terminal 66 is exposed on the high voltage output side.
[0025]
The cartridge 64 is inserted into the mounting portion 11 provided on the barrel portion 4 of the spray gun 1 made of an insulating material, and the output terminal 66 of the high voltage generator 6 is connected to the conducting wire 12. An electrode connection portion 13 of an external electrode is separately provided on the barrel portion 4 of the spray gun 1, and the other end of the conductive wire 12 is exposed as a connection terminal 14 inside the electrode connection portion 13 made of an insulating material.
[0026]
The external electrode 7 attached to the electrode connection portion 13 has the tip electrode 71 exposed at the tip and a detachable portion 72 provided at the rear end, and is entirely formed of an insulating material. The connection terminal 73 is exposed from one end of the attaching / detaching portion 72, and the connection terminal 73 and the tip electrode 71 are connected by a conductor 74. When the external electrode 7 is attached to the electrode connection portion 13 of the barrel 4, the connection terminal 73 and the connection terminal 14 of the barrel 4 are in contact with each other and are electrically connected. In the present embodiment, the connection terminal 73 is formed of a spring in order to ensure connection, but the connection terminal 14 may be formed of a spring.
[0027]
As shown in FIG. 4, the external electrode 7 is inserted into the electrode connecting portion 13 and fixed by locking the locking piece 75 in the locking groove 15 by slightly rotating the electrode. External electrodes can be arranged. This locking method is not limited to this example, and the locking means that is normally used, that is, simply inserts, tightly adheres by its dimensional accuracy, and obtains the necessary fixing force by frictional force, but the deformation of the locking piece and the groove which are deformed. When engaging and disengaging, and detaching, it is possible to select a method such as using a method in which the engaging piece is opened and removed.
[0028]
The external electrode 7 has a simple configuration and can be easily attached and detached, so that it can be easily exchanged. Even if the tip electrode portion becomes dirty or should be damaged by spraying, it can be exchanged immediately without major interruption of the operation. You can continue. In addition, by disposing the connection portion at the rear portion of the atomizing device, only the tip of the thinned external electrode 7 can be placed on the spray region side, and a close position that can increase the charging effect within a range that does not affect the spray is provided. It is possible to install.
[0029]
A further important feature of the present invention is shown in FIGS.
The attachment / detachment portion 72 of the external electrode 7 has a concentric deep groove 76 provided around the conductor 74 and the connection terminal 73 at the center, and the electrode connection portion 13 of the barrel section 4 is also provided with the concentric groove so as to fit therewith. 16 are formed. When the external electrode 7 is attached, the creeping length of the connecting portion reaches the outer surface exposed end portion 77 of the connecting portion while folding the inside of the groove. Therefore, the high voltage charged to the connection terminal 73 can secure a sufficient creepage distance to reach the outer surface exposed end 77, and even if an object at the earth potential contacts the outer surface exposed end 77, unexpected Discharge and dielectric breakdown can be prevented.
The creepage distance for preventing discharge is usually required to be about 15 mm per 10 kV. However, according to the present invention, the attachment / detachment portion can be shortened by folding back, and it is easy to handle, and the configuration of the attachment / detachment portion can be shortened. The length can be reduced.
[0030]
The external electrode 7 is configured such that an accidental electric shock is prevented because the high voltage output through the limiting high resistance 63 is supplied to the high voltage output terminal 66 of the high voltage generator 6 provided on the spray gun 1 side. However, rapid discharge is inevitable with respect to the capacitance charged on the conductor 74 used for the external electrode 7. Therefore, by providing the second high resistance 78 near the tip 71 of the external electrode 7 as shown in FIG. 7, it is possible to obtain further safety. The size of the second high resistance 78 is selected so that the external electrode 7 does not deteriorate the operation and handling.
With such a configuration, the high resistance for restriction is dispersed, the size of the high resistance 63 provided on the high voltage generator 6 side is reduced, the size of the high voltage generator 6 itself is reduced, and the size of the spray gun is reduced. Thus, it is possible to further reduce the weight.
[0031]
Further, the present invention proposes that the external electrode 7 be formed of a flexible or elastic material. That is, the electrode body 70 formed of an insulating resin is made of a resin such as polyethylene to prevent an accidental drop, an impact due to a collision with an object during operation, and the like, and to prevent the electrode body protruding forward of the atomizing device. We can protect damage.
Even in the case where damage is unavoidable due to an impact, for example, as shown in FIG. 7, by including a material portion 79 having low bending strength in a part of the external electrode 7, the strength is higher than that of the electric connection portion 13 on the spray gun main body side. And only the electrode body that can be handled as a consumable item with a simple configuration can be damaged or replaced, thereby minimizing the damage.
[0032]
Needless to say, an externally charged electrostatic gun is used, which is coated with a water-based conductive paint, and the fine particles of the paint ejected from the atomizing device are provided in front of it and discharged to the ejected paint. It is charged when passing through the ionization area formed by, and is applied toward the object to be coated placed on the counter electrode, and the effect is improved, and the atomization device is limited to the air spray gun of this embodiment It is not done.
[0033]
【The invention's effect】
As described above, the present invention makes it possible to easily attach / detach and replace external electrodes on a hand-held electrostatic coating gun having a high-voltage generator. It is possible to obtain a highly practical externally charged electrostatic coating machine with excellent handleability.
[0034]
In addition, the external electrode is provided with a folded part at the attachment / detachment part, so that the required creeping discharge prevention distance can be obtained with a short attachment / detachment part, miniaturizing the external electrode body, and miniaturizing the spray gun itself. Thus, problems in practical use continuation, such as simplification of installation and improvement of operability, can be improved.
[0035]
Furthermore, by minimizing the external electrodes, it is easy to replace them for daily use.Even if they are damaged, the electrostatic painting gun body will not be damaged, and only the inexpensive external electrodes need to be replaced. It can be held down and has a great practical effect.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing an embodiment of the present invention. FIG. 2 is a configuration diagram of a high-voltage generator. FIG. 3 is a partial cross-sectional view of an external electrode mounting portion. FIG. 5 is a cross-sectional view of the external electrode. FIG. 6 is a cross-sectional view of the external electrode. FIG. 7 is a cross-sectional view of the external electrode.
1, spray gun body 2, handle 3, trigger 4, barrel 5, atomizing device 6, high voltage generator 64, cartridge 7, external electrode 9, external charging unit 13, electrode connecting portion 71, tip electrode 72, Detachable part 73, connection terminal 75, locking piece 76, groove 77, exposed end of outer surface

Claims (7)

An atomizing device, which is separated from the path of the paint supplied to the atomizing device while maintaining electrical insulation, and is provided with an externally charged electrode provided to protrude outward and forward from the atomizing device. In the spray gun, the electrode is exposed at the tip at the electrode connection part, which is provided outside the hand-held spray gun equipped with a conductive handle behind the atomization device and is connected to the high voltage output part, and is formed of insulator. An electrostatic coating gun in which an externally charged electrode provided with a detachable portion at the rear end of the electrode assembly is detachably attached to the electrode connection portion. 2. The electrostatic coating gun according to claim 1, wherein the electrode connection portion is provided at a rear portion of the atomizing device. 3. The electrostatic coating gun according to claim 1, wherein an electrode connection portion is provided on the high voltage output portion side via a first high resistance, and a second limiting resistance is provided on the charging electrode side. 2. The static electricity discharge device according to claim 1, wherein the charging electrode attachment / detachment portion has an electrical junction with the high voltage output side, and a distance between the junction and the outer surface exposed end of the connection portion is a distance that can prevent creeping discharge. Electric paint gun. An atomizing device, which is separated from the path of the paint supplied to the atomizing device while maintaining electrical insulation, and is provided with an externally charged electrode provided to protrude outward and forward from the atomizing device. In a spray gun, an externally charged external electrode provided at an electrode connecting portion provided outside the spray gun and to which a high voltage output portion is connected, wherein an electrode is exposed at a tip and a detachable portion is provided at a rear end of an electrode body formed of an insulator. An electrostatic coating gun in which an electrode is detachably attached to the electrode connecting portion, and a creepage portion is provided between an electrical joining portion and an exposed end of an outer surface of the attaching / detaching portion to increase a creepage distance. An atomizing device is provided as a spray gun for electrostatic coating. The atomizing device is separated from the path of the paint supplied to the atomizing device while maintaining electrical insulation, and is provided with an electrode tip protruding outward and forward from the atomizing device. An externally charged electrode attached to a hand-held spray gun, characterized in that the electrode is exposed at the tip and has a bendable portion in which at least a part of an electrode body formed of an insulator is formed of a flexible or elastic material. External charging electrode. An atomizing device is provided as a spray gun for electrostatic coating. The atomizing device is separated from the path of the paint supplied to the atomizing device while maintaining electrical insulation, and is provided with an electrode tip protruding outward and forward from the atomizing device. In an externally charged electrode attached to a hand-held spray gun, the electrode is exposed at the tip and has a connection at the rear, and at least a part of the electrode body made of an insulator has a lower strength than the connection at the spray gun body side. The externally charged electrode of the externally charged electrostatic gun formed.

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