JP6743345B2 - Electrostatic spraying device and electrostatic spraying method - Google Patents

Description

The present invention relates to an electrostatic spraying device and an electrostatic spraying method.

Conventionally, using an electrostatic spraying technique in which a charged liquid is discharged from a cylinder and a large number of minute droplets are formed by a repulsive force due to an electrostatic force to be supplied to an object, when the object has a concave portion, There is known an electrostatic spraying device for efficiently forming a liquid film on the inner surface of a recess (see Patent Document 1).

JP, 2015-192961, A

When such an electrostatic spraying technique is used to apply a liquid such as paint to an object to be coated, for example, a high coating efficiency close to 100% can be obtained.
However, it has been found that when the liquid is applied to the electric field concentration portion such as the end of the rod-shaped object to be coated, the liquid coating efficiency is reduced.

The present invention has been made in view of such circumstances, and an electrostatic spraying device and a static spraying device that can obtain a high liquid coating efficiency even when a liquid is coated on an electric field concentrated portion of an object to be coated. An object is to provide an electrospray method.

The present invention is grasped by the following configurations in order to achieve the above object.
(1) The electrostatic spraying device of the present invention is an electrostatic spraying device that sprays the liquid onto the object to be coated by separating the liquid in a charged state from the nozzle of the liquid spraying unit by the electrostatic force generated by applying a voltage. Of the liquid spraying section having the nozzle, first voltage applying means for applying the voltage between the liquid spraying section and the object to be coated, and the liquid spraying section and the electric field concentration section of the object to be coated. Second voltage applying means for applying the voltage between the members of the conductive material or the semiconductive material arranged in the vicinity to make the member the same polarity as the object to be coated.

(2) In the configuration of (1) above, the second voltage applying means is connected in the middle of the first electric wiring from the first voltage applying means to the object to be coated, and the second voltage applying means is connected by the first voltage applying means. It is provided with the 2nd electric wiring which makes it possible to apply the voltage applied to the above-mentioned subject also to the above-mentioned member, and the 2nd voltage application means makes the above-mentioned member the same potential as the above-mentioned subject. ..

(3) In the configuration of (1) or (2) above, the member is a rod-shaped electrode member having one end arranged in the vicinity of the electric field concentration portion, and the member on the opposite side from the one end of the rod-shaped body. The length to the other end is the length at which the other end is located outside the spray range of the liquid when the one end is arranged in the vicinity of the electric field concentrating portion.

(4) In the configuration according to any one of (1) to (3) above, the member is arranged such that a part of the member is located within a range of 20 mm or less from the electric field concentration portion of the object to be coated. Is arranged.

(5) The electrostatic spraying method of the present invention is an electrostatic spraying method in which the liquid is separated from the nozzles of the liquid spraying section in a charged state by the electrostatic force generated by the application of a voltage and the liquid is sprayed onto the object to be coated. Then, the liquid is sprayed onto the object to be coated in the state where a member made of a conductive material or a semiconductive material having the same polarity as that of the object to be coated is arranged near the electric field concentration portion of the object to be coated.

(6) In the configuration of (5) above, the potential of the member is set to the same potential as the potential of the object to be coated.

(7) In the configuration of (5) or (6) above, the same first article to be coated as the article to be coated is used as the member.

(8) In the configuration of (7) above, a plurality of the first objects to be coated are used as the members.

(9) In the configuration of (7) or (8) above, the electric field concentration part of the first object to be coated is arranged near the electric field concentration part of the object to be coated.

(10) In the configuration of (7) above, the electric field concentration portion of the article to be coated and the first article to be coated is an end portion, and the first article to be coated is with respect to the end portion of the article to be coated. And is arranged in the vicinity of the object to be coated so that the ends of the first object to be coated face each other.

(11) In the configuration of (5) or (6) above, the member is an electrode member different from the object to be coated.

(12) In any one of the configurations (5) to (11), the article to be coated and the member are rod-shaped bodies.

According to the present invention, it is possible to provide an electrostatic spraying device and an electrostatic spraying method capable of obtaining a high liquid coating efficiency even when a liquid is coated on an electric field concentration portion of a coating object.

It is a perspective view of the electrostatic spraying device of the embodiment which concerns on this invention. It is sectional drawing which showed only the liquid spray part of embodiment which concerns on this invention. FIG. 3 is an enlarged cross-sectional view of the liquid spray section of FIG. 2 on the tip side. It is a figure for demonstrating the spraying state etc. of the liquid at the time of spraying a liquid in the state which has not arrange|positioned the member made into the same object as the to-be-coated object of this invention, (a) is a liquid It is a figure which shows a spraying place, (b) is a figure which shows the state of the electric field of the edge part of a to-be-coated article. It is a schematic diagram for demonstrating the cause which becomes a state of Fig.4 (a). FIG. 6 is a diagram for explaining a liquid spray state or the like when liquid is sprayed in a state in which members having the same polarity as the object to be coated described with reference to FIG. 1 are arranged. ) Is a diagram showing a state where the liquid is sprayed, and (b) is a diagram showing the electric field states of the article to be coated 40 and the member 30 by equipotential lines. In the electrostatic spraying device according to the embodiment of the present invention, a member having the same polarity as the object to be coated is the same first object to be coated and a perspective view showing a case where a plurality of first objects to be coated are used. It is a figure. It is a figure which shows the state of the electric field when the edge part of the member of embodiment which concerns on this invention does not taper.

Hereinafter, modes (hereinafter, embodiments) for carrying out the present invention will be described in detail with reference to the accompanying drawings. The same elements are denoted by the same numbers throughout the description of the embodiments.

Unless otherwise specified, expressions such as “tip (edge)” and “front (edge)” indicate the direction of liquid spray in each member, and “rear (edge)” and “rear (edge)”. The expression such as “” represents the side opposite to the liquid spray direction in each member or the like.

FIG. 1 is a perspective view of an electrostatic spraying device 10 according to an embodiment of the present invention.
As shown in FIG. 1, the electrostatic spraying device 10 includes a liquid spraying unit 20 having a nozzle 22, and a first voltage applying unit 50 (voltage power supply) for applying a voltage between the liquid spraying unit 20 and an object 40 to be coated. And a second voltage applying unit including a second electric wire 42a that applies a voltage between the liquid spraying section 20 and the member 30 to make the member 30 have the same polarity as the object 40 to be coated.

In the present embodiment, the case where the first electrical wiring 42 from the first voltage applying means 50 is directly connected to the article 40 to be coated is shown. However, the first electrical wiring from the first voltage applying means 50 is shown. 42 is connected to a holder or the like that holds the object 40 to be coated, and the object 40 to be coated is held by the holder or the like so that the object 40 to be coated is electrically connected to the first voltage applying means 50. Good.

Further, in the present embodiment, the electrostatic spraying device 10 has the grounding means 60 connected to the first electric wiring 42 connected to the article 40 from the first voltage applying means 50, and the article 40 to be coated is provided. Is grounded.
Although the grounding means 60 is not an indispensable requirement, an operator may touch the article 40 to be coated. Therefore, from the viewpoint of safety, the earthing means 60 is provided to ground the article 40. It is preferable.

(Liquid spray part)
FIG. 2 is a cross-sectional view showing only the liquid spraying section 20, and also illustrates a state in which a liquid such as paint is sprayed from the liquid spraying section 20 as described later.

As shown in FIG. 2, the liquid spraying section 20 includes a body portion 21 made of an insulating material in which a liquid flow path 21b having a liquid supply port 21a for supplying a liquid is formed, and a liquid flow of the through hole having the body portion 21. A nozzle 22 provided at the tip of the body portion 21 so as to communicate with the passage 21b, and a mandrel 23 made of a conductive material arranged in the liquid flow passage 21b of the body portion 21 and in the through hole of the nozzle 22 are provided. There is.

The body portion 21 is provided with a hole portion 21c communicating with the liquid flow path 21b in order to take out the mandrel 23 to the rear end side, and a gap between the mandrel 23 is sealed in the hole portion 21c. A seal member 24 is provided to prevent liquid from leaking.
Although the O-ring is used as the seal member 24 in the present embodiment, the seal member 24 is not limited to the O-ring, and any sealable member may be used.

Further, a knob 23a made of an insulating material is provided at the rear end of the mandrel 23 located on the rear end side of the body 21 through the hole 21c, and is provided so as to penetrate almost the center of the knob 23a. An electric wiring connecting portion 23b made of the conductive material is provided.

As shown in FIG. 1, the electric wire 41 from the first voltage applying means 50 is connected to the electric wire connecting portion 23b, and the electric wire connecting portion 23b is brought into contact with the mandrel 23 so that the mandrel 23 and The electrical wiring connection portion 23b is electrically connected.

In the present embodiment, the mandrel 23 is used as the electrode on the liquid spraying section 20 side. However, for example, the nozzle 22 of the liquid spraying section 20 is made of a conductive material, and the nozzle 22 is connected to the first voltage applying unit 50. The electrical wiring 41 may be connected and the nozzle 22 may be used as an electrode on the liquid spraying section 20 side.

Further, as shown in FIG. 2, a female screw structure 21e for screw-connecting the knob 23a is provided on the inner peripheral surface of the rear end opening 21d of the body portion 21, while the tip of the knob 23a is provided. A male screw structure 23c is provided on the outer peripheral surface.

Therefore, the mandrel 23 is detachably attached to the body portion 21 by screwing the male screw structure 23c on the outer peripheral surface of the tip end of the knob portion 23a into the female screw structure 21e of the rear end opening 21d of the body portion 21.
Further, the mandrel 23 can be moved in the front-rear direction by adjusting the screwing amount of the knob 23a, and the position of the distal end surface 23d of the mandrel 23 can be adjusted in the front-rear direction.

Here, in general, the nozzle of the electrostatic spraying device that sprays the liquid is a fine liquid flow path in which the diameter of the through hole through which the liquid flows is small.
This is presumed to be because if the opening diameter of the tip of the nozzle through which the liquid flows is large, a stable atomized state of the liquid cannot be obtained.
For example, depending on the viscosity of the liquid, in the case of a low-viscosity liquid, the opening diameter at the tip of the nozzle is generally set to less than 0.1 mm.

For this reason, the opening at the tip of the nozzle is immediately clogged when the liquid dries, but there is a problem that it is difficult to eliminate this clogging because the opening diameter is small.

However, although the reason will be described later, by using the mandrel 23, it was found that good atomization can be achieved even when the opening diameter at the tip of the nozzle is set to be larger than that in the conventional case. The opening diameter of the opening 22b at the tip of the nozzle 22 of the present embodiment is made as large as 0.2 mm.
As a result, the frequency of occurrence of clogging can be significantly reduced.

The opening diameter of the opening 22b of the nozzle 22 is not limited to 0.2 mm, and in the case of using the mandrel 23, there is no problem even if the opening diameter is about 1.0 mm.

The opening diameter of the opening 22b of the nozzle 22 is preferably 0.1 mm or more, more preferably 0.2 mm or more, and 0.2 mm, considering that clogging is less likely to occur and cleaning can be performed even if clogging occurs. It is more preferable to make it larger.

On the other hand, considering the stability of atomization, the opening diameter of the opening 22b of the nozzle 22 is preferably 1.0 mm or less, more preferably 0.8 mm or less, and further preferably 0.5 mm or less.

Further, in the present embodiment, since the mandrel 23 can be moved in the front-rear direction as described above, even if clogging occurs, the mandrel 23 can be moved to eliminate the clogging.
Furthermore, since the inner diameter of the through hole of the nozzle 22 is also large enough to allow the mandrel 23 to be arranged, it is possible to remove the mandrel 23 and wash a large amount of cleaning liquid.

FIG. 3 is an enlarged view in which the tip end side of the liquid spraying section 20 is enlarged, FIG. 3(a) is a case where the tip end surface 23d of the mandrel 23 is located rearward, and FIG. 3(b) is FIG. This is a case where the tip end surface 23d of the mandrel 23 is located forward of the state of (a).

As shown in FIG. 3A, the nozzle 22 has a tapered inner diameter portion (see range W1) in which the inner diameter is tapered toward the opening portion 22b and the taper angle is α, and the mandrel 23 is provided. Has a tapered portion (refer to range W2) having a taper angle β of which the outer diameter decreases toward the tip surface 23d.

The taper angle α of the tapered inner diameter portion of the nozzle 22 is larger than the taper angle β of the tapered portion of the mandrel 23.
Further, the diameter of the front end surface 23d of the mandrel 23 is set to be smaller than the opening diameter of the opening 22b of the nozzle 22, but the tapered portion of the mandrel 23 gradually increases in diameter toward the rear end side. Therefore, the nozzle 22 is formed to have a portion having a diameter larger than the opening diameter of the opening 22b.

As described above, by forming the tip side of the nozzle 22 and the mandrel 23, by moving the mandrel 23 in the front-rear direction, as can be seen by comparing FIGS. The width of the gap formed with the mandrel 23 can be adjusted, and the amount of liquid discharged from the opening 22b of the nozzle 22 can be adjusted.

Further, by moving the mandrel 23 further to the front side than in the state shown in FIG. 3B, the mandrel 23 abuts on the inner peripheral surface of the nozzle 22 and the opening 22b of the nozzle 22 can be closed. Is.
Therefore, it is possible to prevent the liquid in the nozzle 22 from being dried by closing the opening 22b of the nozzle 22 with the mandrel 23 in a state where liquid such as paint is not sprayed, and to prevent clogging of the nozzle 22. it can.

(Basic spray state of liquid)
Next, with reference to FIG. 2, first, a basic state in which the liquid is sprayed from the liquid spraying section 20 will be described, and thereafter, in the case where the member 30 having the same polarity as the object 40 to be coated is not arranged. The spraying state of the liquid, the spraying state of the liquid when the member 30 having the same polarity as the object 40 to be coated is arranged, and the like will be described.

The liquid supplied to the liquid supply port 21a of the body portion 21 is supplied to the tip end side of the nozzle 22, and the first voltage applying means 50 (see FIGS. 1 and 2) causes the object 40 to be coated and the mandrel 23 to move. It is pulled to the front side by the electrostatic force associated with the voltage applied between and is separated and atomized forward.

The state in which the liquid is separated and atomized will be described more specifically. The liquid is moved forward with respect to the adhesion force due to the surface tension and the viscosity of the liquid on the tip surface 23d of the mandrel 23 and the tip outer peripheral edge 22a of the nozzle 22. By balancing the pulling electrostatic forces, as shown in FIG. 2, a tailer cone 80 is formed in which the liquid supplied to the tip side of the nozzle 22 has a conical shape at its tip.

The Taylor cone 80 is formed by the action of an electric field to separate positive/negative charges in the liquid, and the meniscus at the tip of the nozzle 22 charged with excess charges is deformed into a conical shape.
Then, the liquid is pulled straight from the tip of the Taylor cone 80 by the electrostatic force, and then the liquid is sprayed by the electrostatic explosion.

The sprayed liquid, that is, the liquid that has separated from the nozzle 22 and becomes liquid particles has a dramatically larger area in contact with air than in the state before separation, so that vaporization of the solvent is promoted and the solvent Along with the vaporization, the distance between charged electrons becomes shorter, electrostatic repulsion (electrostatic explosion) occurs, and the liquid particles are further divided into smaller liquid particles.

When this fragmentation occurs, the surface area in contact with air increases more than it did before the fragmentation, which promotes the evaporation of the solvent and causes electrostatic explosion in the same manner as described above. Split into particles.
The liquid is atomized by repeating such electrostatic explosion.

Here, in the present embodiment, the mandrel 23 is provided in the nozzle 22.
If the mandrel 23 is not provided unlike the conventional electrostatic spraying device, the liquid can be attached only to the tip outer peripheral edge 22a of the nozzle 22.

When the opening diameter of the opening 22b of the nozzle 22 is increased in such a state, the liquid can be attached only to the outer peripheral edge 22a of the tip of the nozzle 22, so that, for example, the liquid fluctuates in the vertical and horizontal directions of the nozzle 22. Since it is difficult to form a clean Taylor cone 80 and the Taylor cone 80 itself cannot be maintained, stability of liquid particles leaving the nozzle 22 (stability of particle size, number, charge state, etc.) can be obtained. As a result, it is assumed that stable atomization of the liquid cannot be achieved.

On the other hand, in the present embodiment, the mandrel 23 is arranged in the nozzle 22, and the liquid adheres not only to the tip outer peripheral edge 22a of the nozzle 22 but also to the tip surface 23d of the mandrel 23.
Therefore, even if the opening diameter of the opening 22b of the nozzle 22 is large, since the tip end surface 23d of the mandrel 23 to which the liquid can adhere is present in the central portion of the opening 22b, a stable Taylor cone 80 can be formed and the liquid can be formed. It is considered that the stable atomization of the above is possible.

If the tip surface 23d of the mandrel 23 goes too far forward from the tip outer peripheral edge 22a of the nozzle 22 (that is, the tip surface of the opening 22b of the nozzle 22), the electric field is less likely to act on the liquid coming out of the nozzle 22. If the tip surface 23d of the nozzle 23 recedes too far backward from the tip surface of the opening 22b of the nozzle 22, the state will be the same as that where there is no portion where liquid can adhere to the central portion of the opening 22b.

From this, the position of the tip surface 23d of the mandrel 23 is in the front-back direction along the central axis of the mandrel 23 in the front-back direction with respect to the tip surface of the opening 22b of the nozzle 22 in the state where the liquid is sprayed. It is preferably located within 10 times the opening diameter of the opening 22b at the tip, more preferably within 5 times, and even more preferably within 3 times.

For example, in the present embodiment, the opening diameter of the opening 22b of the nozzle 22 is 0.2 mm, and when the electrostatic force is not taken into consideration, the liquid discharged from the opening 22b of the nozzle 22 has a diameter of about 2 mm at the tip of the nozzle 22. It comes out as a 0.2 mm hemisphere.

Then, the tip of the mandrel 23 reaches the vicinity of the opening 22b of the nozzle 22 so that an electric field (electrostatic force) acts on the liquid emerging at the tip of the nozzle 22 to form a conical Taylor cone 80. It is preferable to be located in the vicinity of the front surface of the opening 22b of the nozzle 22 within 2 mm from the tip surface of the opening 22b of the nozzle 22. In addition, it is preferable that the tip of the mandrel 23 is located within 2 mm behind (retracted from) the tip surface of the opening 22b of the nozzle 22.

As described above, by providing the mandrel 23, stable atomization of the liquid can be performed even if the opening diameter of the opening 22b of the nozzle 22 is increased.
Therefore, the opening diameter of the opening 22b of the nozzle 22 can be made large so that clogging can be suppressed.
Further, since the opening diameter of the opening 22b of the nozzle 22 can be increased, the nozzle 22 can be easily manufactured by machining.

In the present embodiment, the tip of the mandrel 23 is shown as a flat surface as the tip surface 23d, but the tip of the mandrel 23 does not necessarily have to be a flat surface, and the stable Taylor cone 80 is formed. Therefore, for example, the tip end of the mandrel 23 may have a curved surface protruding toward the front side like an R shape.

The liquid sprayed from the liquid spraying unit 20 (nozzle 22) in this way is atomized while repeating electrostatic explosion, and since the atomized liquid is in a charged state, the liquid is sprayed by the first voltage applying means 50. It is attracted by the electrostatic force to the side of the article to be coated 40 that is in a state of different polarity with respect to the spraying section 20, and is applied to the article to be coated 40.

Next, regarding the sprayed state of the liquid when the member 30 having the same polarity as that of the object to be coated 40 is not disposed, and the sprayed state of the liquid when the member 30 having the same pole as that of the object to be coated 40 is disposed The configuration and the like of the liquid spraying section 20 of the present embodiment will be described while explaining.

(When the member 30 is not arranged)
FIG. 4 is a diagram for explaining a sprayed state of the liquid and the like when the liquid is sprayed in a state in which the member 30 having the same polarity as that of the article 40 described with reference to FIG. 1 is not arranged. 4(a) is a diagram showing a state where the liquid is sprayed, and FIG. 4(b) is a diagram showing the state of the electric field at the end portion 40a of the article to be coated 40 by equipotential lines.
It should be noted that FIG. 4A shows only the tip of the nozzle 22 of the liquid spraying section 20 and one end 40a side of the article 40 to be coated, and FIG. 4B shows the end 40a side of the article 40 to be coated. Only showing.

When the member 30 having the same polarity as the object 40 to be coated is not arranged, as shown in FIG. 4B, the end 40a of the object 40 to be coated is an electric field concentration portion where an electric field is concentrated.
Then, as shown in FIG. 4A, the liquid sprayed from the nozzle 22 is in a state in which the liquid is sprayed while being offset slightly above the nozzle 22, and is strongly applied to the object 40 side. There seems to be no attraction.

It is considered that such a phenomenon is caused by the change in the charged state of the sprayed liquid, and it is speculated that a number of factors are combined, but the main factors are as follows. it is conceivable that.

FIG. 5 is a schematic diagram for explaining the cause of the state of FIG. 4A, and is a schematic diagram of the state where the liquid is sprayed, as seen from above.
As described above, the liquid is discharged from the nozzle 22 in the charged state, and atomization proceeds due to electrostatic explosion. Therefore, the atomized liquid is also in the charged state.
Then, the liquid in the charged state is attracted by the electrostatic force to the side of the object to be coated 40 in the state of different polarity, as indicated by the solid arrow L in FIG.

Therefore, the liquid that goes straight from the nozzle 22 toward the article to be coated 40 is applied to the front side of the article to be coated 40 (the side facing the liquid spraying section 20), but in the lateral direction of the article to be coated 40. Even offset and sprayed liquid is attracted to the article to be coated 40 by electrostatic force and is applied to the side surface side or the rear surface side of the article to be coated 40.

On the other hand, when a voltage is applied between the article to be coated 40 and the liquid spraying section 20, the air existing between the article to be coated 40 and the liquid spraying section 20 is also ionized, so that it is charged.

Therefore, the ionized air is also attracted to the article 40 side (see the dotted arrow A in FIG. 5) like the above-mentioned charged liquid particles, but in the case of air, it is applied to the article 40. Therefore, the air drawn toward the object 40 has no place to go.

Therefore, the air attracted to the object 40 side is pressed against the surface of the object 40 by new ionized air or liquid that is pushed around the object 40, and the air is applied to the object 40. It flows on the surface of 40 and moves to the end 40a side of the article 40 to be coated.

Further, as shown in FIG. 4B, since the end portion 40a of the article to be coated 40 is the electric field concentration portion, the charged liquid and the ionized air are likely to gather together, so From the perspective, the situation is such that the flow easily occurs on the end 40a side.

Therefore, air flows along the surface of the article to be coated 40 toward the end portion 40a, and the direction from the end portion 40a along the length direction of the article 40 to be coated in the shape of a rod (upward in FIG. 4A). Direction).
However, the discharged air is discharged (grounded) while flowing along the surface of the object to be coated 40 and approaches a potential state similar to the potential of the object to be coated 40, or a state of the same potential. Become.

Then, when the air in such a potential state is discharged from the end portion 40a of the object 40 to be sprayed into the liquid, the action of removing the charge of the charged liquid occurs, and the removed liquid is covered by the electrostatic force. It will float without being attracted to the coating material 40.

Therefore, as shown in FIG. 4A, it is considered that the liquid that is not strongly attracted to the article 40 is generated.
The reason why the liquid spray is generated slightly upward from the nozzle 22 is presumed that the static-eliminated air drifts to the upper side and acts as a different pole portion.

Therefore, in order to suppress such a phenomenon, in the present embodiment, as shown in FIG. 1, a conductive material or a semiconductive material disposed near the electric field concentration portion (end portion 40a) of the article to be coated 40 is used. The member 30 is provided, and a voltage is applied between the member 30 and the liquid spraying section 20 so that the member 30 has the same polarity as the object 40 to be coated.
In this embodiment, an electrode member made of a conductive material or a semiconductive material having a surface resistance of 10 ¹⁰ Ω or less is used as the member 30.

Specifically, as shown in FIG. 1, it is connected in the middle of the first electric wiring 42 from the first voltage applying means 50 to the object 40 side, and is applied to the object 40 by the first voltage applying means 50. The second electric wiring 42a is provided so that the generated voltage can be applied also to the member 30, and the member 30 is coated by the second voltage applying unit. It has the same polarity as that of the object 40 in the same potential.
However, the second voltage applying means may be configured as another power supply voltage independent of the first voltage applying means 50.

(When the member 30 is arranged)
Hereinafter, a sprayed state of the liquid when the member 30 having the same polarity as the object 40 to be coated is arranged will be described.
FIG. 6 is a diagram for explaining a liquid spray state and the like when liquid is sprayed in a state in which the member 30 having the same polarity as the object 40 to be described with reference to FIG. 1 is arranged. 6(a) is a diagram showing a state where the liquid is sprayed, and FIG. 6(b) is a diagram showing the electric field states of the article 40 and the member 30 by equipotential lines.

Note that FIG. 6A shows only the tip of the nozzle 22 of the liquid spraying section 20 and one end 40a side of the article 40 to be coated, and FIG. 6B shows the end 40a of the article 40 to be coated. Also, only the end 30a side of the member 30 is shown.

Although illustration is omitted, in order to dispose the member 30 as shown in FIG. 6, in the electrostatic spraying device 10 of the present embodiment, the electric field concentration portion of the article 40 to be coated (see FIG. 4B). An arrangement means (holder) for arranging the member 30 so that a part of the member 30 (specifically, the end portion 30a) is located within a predetermined range from the end portion 40a).

As shown in FIG. 6B, the electric field concentration portion of the article 40 is formed so that the end portion 30a of the member 30 faces the end portion 40a of the object 40 which is the electric field concentration portion. If the member 30 is placed in the vicinity of the end 40a, the electric field is formed as if the object 40 and the member 30 are connected to each other, and the electric field of the object 40 is reduced. The electric field concentration at the end portion 40a is significantly reduced.

The arrangement means (holder) for arranging the member 30 so that the object 40 and the member 30 can be brought into a state in which the member 30 is integrated is an electric field concentrating portion of the object 40 (the end of FIG. 4B). It is preferable that the member 30 can be arranged such that a part of the member 30 is located within a range of 20 mm or less from the portion 40a), and the member 30 can be arranged within 15 mm. It is more preferable that the member 30 be arranged within 10 mm.

Therefore, as the overall flow as described above, it is possible to suppress the phenomenon in which the charged liquid or the ionized air flows to the end 40a side of the article 40 to be coated.
Even in the state shown in FIG. 6, it is considered that air flows along the surface of the article to be coated 40, but as can be seen from FIG. 6A, the periphery of the end 40a of the article to be coated 40 is understood. Is in a state in which new ionized air and a charged liquid surround the surroundings, so that the air flowing along the surface of the object to be coated 40 is not discharged and the end portion of the object to be coated 40 is not discharged. It is easy for the liquid to flow toward the outside of the spray range of the liquid on the opposite side of 40a.

Further, even if there is air that has flowed to the end 40a side of the article 40, the air will continue to flow along the surface of the member 30 and will be guided to the outside of the spray range of the liquid. It is not released within the spray range of.

Therefore, it is possible to prevent the charged liquid from being discharged by the discharged air, and it is possible to suppress the decrease in the coating efficiency.

The member 30, which is an electrode member configured as a rod-shaped member, has a length from one end (end 30a) to the other end on the opposite side in order to guide the discharged air outside the spray range of the liquid. It is preferable that the length is such that, when one end (end 30a) is arranged in the vicinity of the electric field concentration portion of the article to be coated 40, the other end is located outside the spray range of the liquid.

However, even if the length of the member 30 is not such that the other end of the member 30 is located outside the spray range of the liquid, if the length of the member 30 is close to the outside of the spray range of the liquid, Since it is considered that the coating efficiency is significantly improved as compared with the case where the member 30 is not arranged, the length at which the other end of the member 30 is located outside the spray range of the liquid is not necessarily limited.

As described above, by spraying the liquid onto the article to be coated 40 with the member 30 having the same polarity as that of the article to be coated 40 arranged near the electric field concentration portion of the article to be coated 40, it is possible to suppress a decrease in the coating efficiency. Is possible.

On the other hand, in the above, the electrode member is used as the member 30, but if the same first coating object as the coating object 40 is used as the member 30, liquid is simultaneously applied to the two coating objects 40. Since the application work can be performed, instead of using the member 30 which is an electrode member different from the object 40 to be coated, the member 30 may be the same first object to be coated 40.

Therefore, the electrode member different from the object to be coated 40 is not an indispensable requirement, and at least has a second voltage applying unit that makes the first object to be coated used as the member 30 have the same polarity as the object to be coated 40. Good.

In the case of using the dedicated electrode member for the member 30, as in the case of using the object 40 to be coated, the arrangement means (holder) for arranging the member 30 each time the type of the object 40 to be coated changes. The advantage is that the design does not need to be changed.

Although the electrostatic spraying device 10 of the present invention has been described above based on the specific embodiments, the present invention is not limited to the above specific embodiments.

In the above embodiment, the case where one member 30 is used for the article 40 to be coated has been described, but as mentioned above, the member 30 may be the same first article to be coated 40. Therefore, when the same first article to be coated (object to be coated 40) as the object to be coated 40 is used as the member 30, as shown in FIG. 7, a plurality of first objects to be coated (object to be coated 40) should be used. Alternatively, the liquid may be applied to a large number of objects 40 at once to improve the efficiency of the work.

Further, in the above embodiment, the end portion 30a of the member 30 has a tapered shape, but as shown in FIG. 8, even if the end portion 30a of the member 30 is not tapered, a similar electric field state can be created. However, the end portion 30a of the member 30 is not limited to be tapered.

Further, in the above embodiment, the member 30 is directly connected to the second electric wiring 42a, but the second electric wiring 42a is connected to the arrangement means (holder) for disposing the member 30, and the arrangement means is arranged. The second electric wiring 42a may be electrically connected to the member 30 via.

In addition, when the article 40 to be coated has an outer shape that fits within the spray range of the liquid, the problem of a decrease in coating efficiency as described above easily occurs, and when the article 40 to be coated is a rod-shaped body. In the electrostatic spraying device 10 of the present invention and the electrostatic spraying method using the electrostatic spraying device 10, the coating object 40 has an outer shape that fits within the spraying range of the liquid. Moreover, it is particularly effective in the case of a rod-shaped body.

However, when the article to be coated 40 as a whole has an outer shape that fits within the spray range of the liquid, and is not a problem that occurs only when it is a rod-shaped object, a portion where the article to be coated 40 projects, etc. Since it is considered that the same problem will occur even when it has the above, the object to be coated 40 to which the present invention is applied is not necessarily limited to the rod-shaped object, and a projection or the like in which an electric field concentration part occurs The thing to have is also contained in the to-be-coated article 40 used as an application target.

As described above, the present invention is not limited to the above embodiment, and appropriately modified and improved ones are also included in the technical scope of the present invention. It is clear from the description of the claims.

DESCRIPTION OF SYMBOLS 10 Electrostatic spraying device 20 Liquid spraying part 21 Body part 21a Liquid supply port 21b Liquid channel 21c Hole part 21d Rear end opening 21e Female screw structure 22 Nozzle 22a Tip outer peripheral edge 22b Opening 23 Mandrel 23a Picking part 23b Electrical wiring connection Part 23c Male screw structure 23d Tip surface 24 Sealing member 30 Member 30a End 40 Object to be coated 40a End 41 Electric wiring 42 First electric wiring 42a Second electric wiring 50 First voltage applying means 60 Grounding means 80 Taylor cone

Claims (10)

An electrostatic spraying device for spraying a liquid onto an object to be coated by separating the liquid in a charged state from a nozzle of a liquid spraying unit by an electrostatic force generated by applying a voltage,
The liquid spraying section having the nozzle,
First voltage applying means for applying the voltage between the liquid spraying section and the article to be coated,
The second voltage is applied between the liquid spraying section and a member made of a conductive material or a semiconductive material, which is arranged in the vicinity of the electric field concentration section of the object to be coated, so that the member has the same polarity as the object to be coated. Voltage applying means ,
The electric field concentration portion of the article to be coated and the member is an end portion,
The electrostatic spraying device , wherein the member is arranged in the vicinity of the object to be coated so that the end portion of the member faces the end portion of the object to be coated . The second voltage applying means is connected in the middle of the first electric wiring from the first voltage applying means to the object side, and the voltage applied to the object by the first voltage applying means is applied to the object. It is equipped with a second electric wire that can be applied to the member,
The electrostatic spraying device according to claim 1, wherein the second voltage applying unit sets the member to the same potential as the object to be coated. The member is a rod-shaped electrode member having one end arranged near the electric field concentration portion,
The length from the one end to the other end on the opposite side of the rod-shaped body is such that, when the one end is arranged in the vicinity of the electric field concentrating portion, the other end is located outside the spray range of the liquid. The electrostatic spraying device according to claim 1, wherein the electrostatic spraying device is provided. The arrangement means for arranging the member so that a part of the member is positioned within a range of 20 mm or less from the electric field concentration portion of the object to be coated is provided. Item 4. The electrostatic spraying device according to any one of items 3. An electrostatic spraying method of spraying a liquid onto a coating object by separating the liquid in a charged state from a nozzle of a liquid spraying section by an electrostatic force generated by applying a voltage,
The liquid is sprayed on the object to be coated in a state in which a member made of a conductive material or a semiconductive material having the same polarity as the object to be coated is arranged in the vicinity of the electric field concentration portion of the object to be coated ,
The electric field concentration portion of the article to be coated and the member is an end portion,
Said member, the electrostatic spraying method, characterized in Rukoto disposed in the vicinity of the end portion the object to be coated so as to face the said member relative to said end portion of the article to be coated. The electrostatic spraying method according to claim 5, wherein the potential of the member is the same as the potential of the object to be coated. The electrostatic spraying method according to claim 5 or 6, wherein the same first article to be coated is used as the member. The electrostatic spraying method according to claim 7, wherein a plurality of the first objects to be coated are used as the members. The electrostatic spraying method according to claim 5 or 6, wherein the member is an electrode member different from the object to be coated. The electrostatic spraying method according to any one of claims 5 to 9 , wherein the article to be coated and the member are rod-shaped bodies.

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