JP3396709B2 - Friction electrification gun for electrostatic painting - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a triboelectric charging gun for electrostatic coating in which powder coating is charged by friction.

[0002]

2. Description of the Related Art A friction charging gun has a charging tube made of a non-conductive resin, and the powder coating is passed through the charging tube at a high speed, and the friction between the powder coating and the charging tube causes powder coating. Is to be charged. Conventionally, in order to improve the contact efficiency between the powder coating and the non-conductive resin, the charging tube is a double tube of the inner tube and the outer tube, and the powder coating is placed in the space between the inner tube and the outer tube. There is one that is made to pass.

The frictional charging gun charges the powder coating material by friction with a non-conductive resin, and an electric charge of the opposite polarity, which is the same amount as the electric charge charged by the powder coating material, is generated on the wall surface of the charging tube. Therefore, in order to continuously charge the powder coating material, it is necessary to quickly release the electric charge on the wall surface of the charging tube that is generated and accumulated due to the friction between the powder coating material and the wall surface of the charging tube. Conductive paint or conductive material (for example, iron,
A conductive layer made of aluminum) is formed, and the electric charge accumulated in the charging tube is released from this conductive layer.
Normally, the charging tube is made of a fluororesin such as polytetrafluoroethylene, and epoxy, acrylic, polyester, etc. are used as the powder coating material.
The powder coating is positively charged and the charging tube is negatively charged.
Therefore, a ground wire is usually connected to the conductive layer of the charging tube, and the charge of the charging tube is removed via this ground wire.

[0004]

By the way, in such a triboelectric charging gun, in order to stably supply an electric charge to the powder coating material and efficiently charge it, the powder coating material generated on the wall surface of the charging tube is used. It is necessary to allow the opposite polarity charge to escape through the conductive layer as quickly as possible.

However, since the charging tube is made of a non-conductive resin material and has a large thickness, it is difficult to smoothly remove the charges generated on the wall surface of the charging tube.

The inner tube and the outer tube forming the charging tube may be thinned so that the charges generated on the wall surface of the charging tube can easily flow to the conductive layer. However, if the charging tube is thinned, the charging tube Since the strength of itself cannot be maintained, there is a limit to how thin it can be made.

As another method, for example, there is a method in which a large number of holes are formed in the charging tube of the outer tube so that the charges generated on the wall surface of the charging tube can easily flow into the conductive layer. When the body paint is easily clogged and the holes are clogged, there is a problem that the electric charge generated on the wall surface of the charging tube is less likely to flow into the conductive layer and the charging effect is deteriorated.

Therefore, according to the present invention, the electric charge generated on the wall surface of the charging tube can be instantly removed without thinning the thickness of the charging tube or forming a hole, and the powder coating material is provided. It is intended to efficiently supply the electric charge to the electric field.

[0009]

In order to solve the above problems, the present invention divides at least one of an inner tube and an outer tube forming a charging tube into a plurality of short tubes in the carrying direction,
A conductive ring that comes into contact with a conductive layer provided inside the inner pipe or outside the outer pipe is sandwiched between the abutting end faces of the short pipe.

[0010]

With the above structure, the charges generated on the wall surface of the charging tube smoothly flow into the conductive layer through the conductive ring, and the charges are not accumulated in the charging tube.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows an example of a triboelectric charging gun of the present invention, which is a charging tube consisting of a double tube of an inner tube 1 and an outer tube 2 made of a non-conductive resin such as polytetrafluoroethylene. And having a space 3 between the inner pipe 1 and the outer pipe 2,
The powder coating material supplied from the powder coating material supply hose 5 connected to the lower end of the grip 4 passes at a high speed, and the powder coating material is charged by friction during the passage.

The inner pipe 1 and the outer pipe 2 are housed in a protective pipe 6.

The inner tube 1 is divided into a plurality of short tubes in the powder coating material conveying direction. Inside the inner tube 1, a conductive layer 7
A conductive tube made of aluminum, iron or the like is inserted to form the. The conductive layer 7 may be formed by coating a conductive paint or a conductive material. The conductive layer 7 is connected to the ground wire via an ammeter.

A conductive ring 8 made of a conductive material such as aluminum or iron is fitted between the abutting end surfaces of the short tubes constituting the inner tube 1 so as to come into contact with the conductive layer 7. .

In the embodiment shown in FIGS. 1 and 2, the outer tube 2
Is composed of one continuous tube without being divided, but this is divided in the same manner as the inner tube 1 and a conductive ring is fitted between the short pipe and the abutting end faces of the short pipe. The conductive ring may be brought into contact with a conductive layer provided on the outer peripheral surface of the outer tube 2.

Next, FIG. 3 shows a preferred embodiment of the inner pipe 1 divided into a plurality of short pipes. The outer peripheral edge portion of the butt end face of the short pipe is obliquely cut to form an inclined surface 9. As a result, when the short pipes are butted to form the inner pipe 1, the inner pipe 1
Recesses are formed at predetermined intervals on the outer peripheral surface of the. Due to this recess, when the powder coating material passes through the space 3 between the inner pipe 1 and the outer pipe 2, the air flow in the space 3 becomes a turbulent flow, and the outer peripheral surface of the inner pipe 1 and the inner pipe 2 Since the number of times the powder coating material that contacts the peripheral surface increases, the charge amount of the powder coating material increases.

(Effect Confirmation Test) In order to confirm the effect of the present invention, the inner pipe 1 and the outer pipe 2 are made of a combination of short pipes made of polytetrafluoroethylene, and the short pipes of the inner pipe 1 are butted. When the conductive ring 8 is fitted to the end face, when the conductive ring 8 is fitted to the abutting end faces of both the short pipes of the inner pipe 1 and the outer pipe 2, both the inner pipe 1 and the outer pipe 2 are made conductive. The charge amount of the powder coating was measured when the sex ring was not fitted. As the short tube, two types were used, one having a peripheral edge cut diagonally with a width of 1.5 cm to form an inclined surface and the other having no inclined surface.

The used gun is The Friction HT-226 (trade name) manufactured by Matsuo Sangyo, and the discharge rate is 100 g / mi.
n, and the conveying air pressure was 3.0 kg / cm ² . The paint used was polyester ivory (manufactured by ICI), epoxy white (manufactured by Shinto Paint Co., Ltd.), and epoxy-polyester gray (manufactured by Takashi Kubo Paint).

The test results are shown in Table 1.

[0020]

[Table 1]

[0021]

As described above, according to the present invention, the charge generated on the wall surface of the charging tube is instantly removed from the conductive ring between the short tubes, and the charge is efficiently supplied to the powder coating material. Therefore, there is an effect that the charge amount of the powder coating material is increased.

Further, when the inner pipe and the outer pipe are divided into a plurality of short pipes, the inner pipe and the outer pipe can be easily assembled, and when they are worn or damaged, they can be partially replaced. Therefore, the running cost can be reduced.

[Brief description of drawings]

FIG. 1 is a partial vertical sectional side view of a friction charging gun for electrostatic coating according to the present invention.

FIG. 2 is an enlarged sectional view of an inner pipe and an outer pipe.

FIG. 3 is an enlarged sectional view of the inner pipe.

[Explanation of symbols]

1 inner tube 2 outer tube 3 space 4 grip 5 Powder coating supply hose 6 protection tube 7 Conductive layer 8 Conductive ring 9 inclined surface

Claims (2)

(57) [Claims] 1. A charging tube comprising a double tube of an inner tube and an outer tube made of a non-conductive resin, wherein a conductive layer is provided on at least one of the inside of the inner tube and the outside of the outer tube. In a friction charging gun for electrostatic coating, in which a powder paint supply device for supplying powder paint by carrier air is connected to the space between the outer pipes, and the powder paint is charged by friction, At least one of them is divided into a plurality of short pipes in the transport direction, and a conductive ring that comes into contact with the conductive layer provided inside the inner pipe or outside the outer pipe is inserted between the abutting end faces of the short pipes. A friction charging gun for electrostatic coating. 2. The triboelectrification for electrostatic coating according to claim 1, wherein the peripheral portion of the abutting end surface of the short pipe facing the space between the inner pipe and the outer pipe is formed as an inclined surface. gun.