JPH0780362A - Triboelectrification gun for electrostatic coating - Google Patents

Abstract

PURPOSE:To provide an electrifying gun for electrostatic coating enabling to impart sufficient electric charge to a powdery coating material without making an electrifying part consisting of a nonconductive resin tube longer or without twisting it. CONSTITUTION:A preliminary electrifying part performing dispersion and electrification is provided at the inlet side of the electrifying part consisting of the nonconductive resin tube 10 by turning the inside wall face of the nonconductive resin ring 33 and sufficient electric charge is imparted to the powdery coating material.

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 brought into contact with a non-conductive resin and the powder coating is charged by friction between the two.

[0002]

2. Description of the Related Art A friction charging gun has a structure in which a charging section made of a non-conductive resin tube is provided in a gun body having a paint inlet at one end and a paint outlet at the other end. There is.

By the way, in the friction charging gun having the above structure, in order to sufficiently charge the powder coating material, it is necessary to increase the number of contact between the powder coating material and the non-conductive resin tube.

Therefore, since the conventional triboelectric charging gun inevitably has a long overall length, it is difficult to mount it on a reciprocator or a coating robot, and the coating range is limited.

Conventionally, there is also a friction charging gun in which the non-conductive resin tube is twisted many times (50 to 70 times) to increase the number of contact between the powder coating and the non-conductive resin tube. The wear of the inner surface of the non-conductive resin tube is severe, and the problem that the non-conductive resin tube is immediately broken, and it becomes difficult to clean the twisted non-conductive resin tube by air blow when changing colors, There is a problem that color change is virtually impossible.

Therefore, according to the present invention, the entire length of the gun is not increased or the non-conductive resin tube is not twisted.
It is intended to obtain a triboelectric charging gun capable of giving a sufficient electric charge to powder coatings.

[0007]

In order to solve the above problems, the present invention comprises a non-conductive resin tube in a gun body having a paint inlet at one end and a paint outlet at the other end. In a friction charging gun for electrostatic coating provided with a charging section, a non-conductive resin ring is provided between the coating material inlet portion and the charging portion, and powder coating material introduced from the coating material inlet portion is used as the non-conductive resin ring. The pre-charging portion is formed of a flow member facing the inner wall surface of the.

[0008]

[Function] When the powder coating material is introduced toward the inner wall surface of the non-conductive resin ring by the flow member, the powder coating material swirls in the non-conductive resin ring, whereby the powder coating material is dispersed and the dispersed powder is dispersed. The body paint contacts the inner wall surface of the non-conductive resin ring and is charged.

When the powder paint precharged in this way is introduced into the charging section composed of the non-conductive resin tube, the charge of the powder paint is stabilized and the amount of charge is increased.

Therefore, the total length of the gun can be shortened, and the non-conductive resin tube of the charging section can be straightened without twisting.

[0011]

Embodiments of the present invention will be described below with reference to the accompanying drawings.

The friction charging gun according to the present invention has a gun body 1 having a paint inlet at one end and a paint outlet at the other end.
A charging section made of a non-conductive resin tube 10 is provided in the inside 1, and a preliminary charging section is provided on the inlet side of this charging section, that is, on the rear side.

The charging unit is a resin-made cylindrical gun body 11
Inside, 6 straight non-conductive resin tubes 10
They are evenly arranged around the center pipe 12. The rear end of the gun body 11 is covered with a rear barrel cap 13, and the rear bundle holder 14 is fitted inside the rear barrel cap 13.
A rear bundle cap 15 that holds the rear end of the center pipe 12 and the rear end of the non-conductive resin tube 10 around the center pipe 12 is fitted inside. Non-conductive resin tube 1
The holding hole of the rear bundle cap 15 that holds the rear end of 0 penetrates rearward. On the other hand, the holding hole of the rear bundle cap 15 that holds the rear end of the center pipe 12 is
It does not penetrate to the rear side, and the protrusion 16 is formed on the rear side thereof.

A bundle cap retainer 17 for retaining the periphery of the rear surface of the rear bundle cap 15 is screwed into the rear end of the rear bundle holder 14.

On the other hand, the front end of the non-conductive resin tube 10 is held by a front bundle cap 19 fixed to the front end of the center pipe 12 by a resin screw 18, and the front bundle cap 19 has a front end of the non-conductive resin tube 10. Is formed with six holding holes. An O-ring 20, an O-ring retainer 21, and an O-ring 22 are sequentially attached to a non-conductive resin tube 10 projecting forward from the holding hole of the front bundle cap 19, and a sub-muzzle having an inner surface narrowed forward in front of the O-ring 23 is fitted. The sub muzzle 23, the O-ring retainer 21, and the front bundle cap 19 are fixed to the gun body 11 by a front bundle holder 24 screwed inside the front end of the gun body 11.

The non-conductive resin tube 10 is made of, for example, ethylene tetrafluoride, and its outer peripheral surface is covered with an aluminum foil 25 and an aluminum tube 26 as a conductive layer.

A hose connector 27, which constitutes a paint inlet, is connected to the rear of the charging portion constructed as described above. A transport hose for supplying powder coating is connected to the hose connector 27. The hose connector 27 is a rear barrel cap 13 at the rear end of the gun body 11.
It is fixed by a rear cap nut 28 and a rear cap 29. An orifice 30 having a narrowed central passage is fitted inside the rear cap 29, and an accelerating air introducing pipe 31 for introducing accelerating air is connected to the rear side of the orifice 30.

A preliminary charging section is provided between the orifice 30 and the rear bundle cap 15. The pre-charging portion is composed of a non-conductive resin ring 33 and a flow member 32 for introducing the powder coating material ejected together with air from the orifice 30 toward the inner wall surface of the non-conductive resin ring 33. A plurality of holes are formed obliquely outward in the direction toward the front 32. By passing through these holes, the powder coating material swirls and contacts the inner wall surface of the non-conductive resin ring 33 to be dispersed.

The non-conductive resin ring 33 is, for example,
It is formed of ethylene tetrafluoride, and when the powder coating material comes into contact with it, an electric charge is added to the powder coating material. Further, the orifice 30 and the flow member 32 are also made of ethylene tetrafluoride, and an electric charge is added to the powder paint even when the powder paint passes through these members.

When the powder coating material is charged in the orifice 30, the flow member 32 and the non-conductive resin ring 33, the charge of the opposite polarity to the charge of the powder coating material is charged to these members by the same amount. Therefore, in order to release this electric charge, an aluminum rear cap earth ring 34 is fitted on the outer surface of the orifice 30, and the rear cap earth ring 34 includes the aluminum bundle cap retainer 17 and the aluminum rear bundle holder. Through 14,
Earth electrode 3 attached to rear bundle holder 14
5 is electrically connected.

The rear bundle holder 14 to which the ground electrode 35 is connected is a non-conductive resin tube 10.
The aluminum foil 25 and the aluminum tube 26 on the outer surface of the non-conductive resin tube 10 are also in contact with the non-conductive resin tube 10.

On the other hand, a muzzle 36 forming a paint outlet is connected in front of the charging section. The muzzle 36 is attached to the front end of the gun body 11 by a front cap nut 37, and a flow agitator 38 for evenly mixing the powder coating material passing through the sub muzzle 23 is fitted between the muzzle 36 and the sub muzzle 23. Has been.

In front of the muzzle 36, a pattern cap 39 for forming an injection pattern of powder coating material is covered.

The sub-muzzle 23, the flow agitator 38, the muzzle 36, and the pattern cap 39 are also made of the same material as the non-conductive resin tube 10, for example, ethylene tetrafluoride, so that the powder paint is also charged. I have to. Therefore, the muzzle earth rings 40 and 41 are fitted between the muzzle 36 and the pattern cap 34 and on the outer surface of the flow agitator 38, and the muzzle earth rings 40 and 41 are not connected to each other via the aluminum front bundle holder 24. Conductive resin tube 10
It is electrically connected to the aluminum tube 26 on the outer surface of the ground electrode 35, so that the electric charge opposite to the powder paint charged on the pattern cap 39, the muzzle 36, the flow agitator 38 and the sub muzzle 23 is released from the ground electrode 35. .

In the triboelectric charging gun constructed as described above, a hose connector 27 is connected to a powder paint transport hose to introduce the powder paint together with the carrier air, and the acceleration air introducing pipe 31 into the orifice 30. When the accelerated air is introduced, the accelerated air is uniformly mixed with the carrier air while passing through the orifice 30, so that the powder coating material is applied to the orifice 3.
0, the powder coating material that has passed through the flow member 32 at high speed is uniformly dispersed while swirling in the non-conductive resin ring 33, and enters the non-conductive resin tube 10 in that state. Before entering the non-conductive resin tube 10, the powder coating material contains the orifice 30 and the flow member 3.
2 and the non-conductive resin ring 33 are brought into contact with each other to give an electric charge. Further, a large amount of electric charge is applied to the powder coating material while passing through the non-conductive resin tube 10, and finally the powder coating material comes into contact with the inner surfaces of the sub-muzzle 23, the flow agitator 38, the muzzle 36 and the pattern cap 39. Also gives an electric charge. Therefore, the charge of the powder coating material ejected from the pattern cap 39 is stabilized, and the charge amount is large.

Further, the orifice 30, the flow member 32, and the rear bundle cap 1 which constitute the above-mentioned friction charging gun.
5, each member such as the non-conductive resin tube 10 can be disassembled into their respective members. Therefore, when the non-conductive resin tube 10 is worn, the non-conductive resin tube 10 is replaced. Is possible.

Further, since the non-conductive resin tube 10 is formed straight, the inner surface can be easily cleaned by air blow, and the color can be changed by cleaning.

By the way, in the above-mentioned pre-charging portion and charging portion, in order to stably supply the electric charge to the powder coating material and efficiently charge it, the non-conductive resin ring 33 or the wall surface of the non-conductive resin tube 10 is used. It is preferable that the electric charge having the opposite polarity to the powder coating material generated in (2) is released through the conductive layer on the outer peripheral surface as soon as possible.

For this reason, as shown in the conceptual diagram of FIG. 5, needle electrodes 42 are provided at predetermined intervals on the non-conductive resin ring 33 of the pre-charging portion and the non-conductive resin tube 10 of the charging portion, and the outer surface is electrically conductive. When the contact is made with the layer 43 and the tip is inserted so as to project from the inner wall surface of the non-conductive resin ring 33 or the non-conductive resin tube 10, the non-conductive resin ring 33 or the wall surface of the non-conductive resin tube 10 is generated. The electric charge having the opposite polarity to that of the powder coating material is applied to the outer surface of the conductive layer 43 from the needle-shaped electrode protruding on the wall surface.
Flow smoothly to the opposite polarity charge is no longer accumulated,
The powder paint is charged one after another. A ground wire 45 is connected to the conductive layer 43 via an ammeter 44. In FIG. 5, the conductive layer indicated by the reference numeral 43 is the aluminum bundle cap retainer 17 in the case of the non-conductive resin ring 33, and the aluminum foil 25 and the aluminum tube on the outer surface in the case of the non-conductive resin tube 10. 26. Further, in FIG. 5, the powder coating material is indicated by reference numeral 46. When the powder coating material is epoxy or polyester, the powder coating material is positively charged, and the non-conductive resin ring 33 and the non-conductive resin ring are used. On the other hand, negative charges are generated on the wall surface of the resin tube 10.

In order to confirm the effect of the needle-shaped electrode 42, there is a difference in the charge amount of the powder coating material when the needle-shaped electrode 42 is provided on the non-conductive resin ring 33 and when it is not provided. When the swelling was measured, the results shown in Tables 1 and 2 were obtained. Similarly, when the needle electrode 42 was provided on the non-conductive resin tube 10 and the needle electrode 42 was not provided, the difference in the charge amount of the powder coating material was measured. The results shown in are obtained. The materials of the non-conductive resin ring 33 and the non-conductive resin tube 10 used in this test are ethylene tetrafluoride.

As a result, it was found that the larger the discharge amount, the greater the difference in the charge amount. This is because the negative charge generated on the wall surface of the non-conductive resin ring 33 or the non-conductive resin tube 10 is instantly removed from the needle-shaped electrode 42, and the powder coating material is rubbed efficiently one after another to obtain a positive charge. It is thought that this is because it is possible.

[0032]

[Table 1]

[0033]

[Table 2]

[0034]

[Table 3]

[0035]

[Table 4]

[0036]

According to the present invention, as described above, before the powder coating material is introduced into the charging portion composed of the non-conductive resin tube, the powder coating material is provided in the preliminary charging portion including the non-conductive resin ring. And the charging is performed, the powder coating can be sufficiently charged even if the charging section is shortened and the non-conductive resin tube of the charging section is not twisted.

[Brief description of drawings]

FIG. 1 is a vertical sectional front view showing an example of a triboelectric charging gun according to the present invention.

FIG. 2 is an enlarged view of the latter half of FIG.

FIG. 3 is an enlarged view of the first half of FIG.

FIG. 4 is a vertical side view of the center of FIG.

FIG. 5 is a partial conceptual diagram of another embodiment of the present invention.

[Description of Reference Signs] 10 non-conductive resin tube 25 aluminum foil 26 aluminum tube 30 orifice 31 accelerated air introduction tube 32 flow member 33 non-conductive resin ring 42 slanted electrode

Claims (6)

[Claims] 1. A friction charging gun for electrostatic coating, comprising: a gun main body having a paint inlet at one end and a paint outlet at the other end; A pre-charging portion including a non-conductive resin ring and a flow member for directing the powder coating material introduced from the coating material inlet portion to the inner wall surface of the non-conductive resin ring is provided between the charging portion and the charging portion. A friction charging gun for electrostatic coating. 2. Between the paint inlet and the flow member,
The friction charging gun for electrostatic coating according to claim 1, wherein an acceleration air introducing pipe is connected, and an orifice is provided between the connecting position of the acceleration air introducing pipe and the flow member. 3. The friction charging gun for electrostatic coating according to claim 1, wherein the charging section is divided into a plurality of straight non-conductive resin tubes arranged in parallel. 4. A non-conductive resin tube and a non-conductive resin ring are respectively provided with a conductive layer on an outer surface thereof, and the non-conductive resin tube and the non-conductive resin ring are grounded via the conductive layer. The triboelectric charging gun for electrostatic coating according to any one of claims 1 to 3, wherein 5. A needle-shaped electrode is inserted into the non-conductive resin tube at a predetermined interval so that the needle-shaped electrode comes into contact with the conductive layer on the outer surface and the tip projects from the inner wall surface of the non-conductive resin tube. The friction charging gun for electrostatic coating according to claim 4. 6. The non-conductive resin ring, wherein needle electrodes are inserted at predetermined intervals so as to contact the conductive layer on the outer surface and the tip projects from the inner wall surface of the non-conductive resin ring. The friction charging gun for electrostatic coating according to claim 4 or 5.