WO2017164198A1 - Electrostatic spray device - Google Patents

Abstract

The present invention provides an electrostatic spray device that is able to prevent, costlessly and without time and effort, a coating liquid from coating a to-be-coated object at a portion thereof where no coating is desired. This electrostatic spray device is provided with: a voltage application unit; a liquid sprayer part having a nozzle for causing a liquid to be released in an electrostatically charged state using an electrostatic force generated by the voltage application unit; and a coating preventive electrode which generates an electric field between the coating preventive electrode and the portion of the to-be-coated object where no liquid coating is to be performed. The voltage application unit is configured to apply a voltage such that, when the electric potential of the to-be-coated object is defined as a reference potential, the liquid sprayer part has a first electric potential different from the reference potential, and the coating preventive electrode has a second electric potential. The second electric potential is different from the reference potential, and has the same direction of polarity as the first electric potential.

Description

Electrostatic spraying equipment

The present invention relates to an electrostatic spraying device.

Conventionally, a nozzle that sprays the solution material in a state where a voltage is applied to the solution material, and a mask that is disposed in the vicinity of the substrate between the nozzle and the substrate and includes openings having a predetermined opening pattern. A thin film forming apparatus is disclosed (see Patent Document 1). In this thin film forming apparatus, the solution material sprayed from the nozzle is deposited as a thin film on the substrate. A portion of the opening portion of the mask on the nozzle side is configured to have an opening area larger than a portion of the opening portion of the mask on the substrate side.

JP 2014-147891 A

By the way, there are various shapes of objects to be coated with a liquid such as paint, and even in the same shape of the object to be coated, there is a case where a portion where the liquid is not desired to be applied is changed. . It is expensive to produce a mask each time depending on the shape of the object to be coated and the area where the liquid is applied. In addition, prior to the operation of applying the liquid, an operation of installing the mask on the object to be coated is necessary, which takes time.

An object of the present invention is to provide an electrostatic spraying device capable of avoiding the liquid from being applied to a portion of the object to which the liquid is not desired to be applied without cost and effort.

(1) An electrostatic spraying apparatus for applying a liquid to an object to be coated according to an embodiment of the present invention uses a voltage applying device and electrostatic force generated by the voltage applying device to separate the liquid in a charged state. A liquid spraying portion having a nozzle for coating, an anti-coating electrode, and an anti-coating electrode for generating an electric field between the anti-coating electrode and a portion of the article to which liquid is not applied; . In the voltage application device, when the potential of the object to be coated is set as the reference potential, the potential of the liquid spraying portion becomes the first potential different from the reference potential, and the potential of the anti-coating electrode is the second potential. It is comprised so that a voltage may be applied. The second potential is a potential different from the reference potential, and the polarity direction is the same as the first potential.

(2) In the embodiment of the above (1), the coating preventing electrode is a liquid with respect to a virtual plane orthogonal to the straight line at a point where a straight line connecting the tip of the nozzle and the coating object at the shortest distance intersects the coating object. Located on the opposite side of the spray section.

(3) In the embodiment of the above (1) or (2), the anti-coating electrode is a rod-shaped member formed from a conductive material or a semiconductive material.

(4) In any one embodiment of the above (1) to (3), the application preventing electrode is located on the opposite side to the liquid spraying part with respect to the object to be coated.

(5) In any one embodiment of the above (1) to (4), the voltage application device is between the object to be coated and the liquid spraying unit and between the object to be coated and the anti-coating electrode. Apply voltage.

(6) In any one embodiment of the above (1) to (5), the first potential and the second potential are substantially the same potential.

(7) In any one embodiment of the above (1) to (6), the electrostatic spraying device includes a proximity electrode disposed in the vicinity of the nozzle. The voltage application device is configured to apply a voltage such that the potential of the proximity electrode is a third potential between the reference potential and the first potential. The third potential is set so that the potential difference between the first potential and the third potential is a potential difference that can generate an electrostatic force that causes the liquid to leave the nozzle in a charged state.

According to an embodiment of the present invention, it is possible to provide an electrostatic spraying device capable of avoiding liquid from being applied to a portion of an object to which liquid is not to be applied without cost and effort. Can do.

It is a perspective view of the electrostatic spraying apparatus of 1st Embodiment which concerns on this invention. It is sectional drawing of the electrostatic spraying apparatus of 1st Embodiment which concerns on this invention. It is sectional drawing which showed only the liquid spraying part of 1st Embodiment which concerns on this invention. It is an expanded sectional view of the front end side of the liquid spraying part of FIG. It is an expanded sectional view of the front end side of the liquid spraying part of FIG. It is a side view which shows the state of the electric field of 1st Embodiment which concerns on this invention. It is a perspective view of the electrostatic spraying apparatus of 2nd Embodiment which concerns on this invention. It is a top view which shows the state of the electric field of 2nd implementation mobile phone based on this invention. It is a perspective view of the electrostatic spraying apparatus of 3rd Embodiment which concerns on this invention. It is a perspective view of the electrostatic spraying apparatus of 4th Embodiment which concerns on this invention.

DETAILED DESCRIPTION Hereinafter, embodiments for carrying out the present invention (hereinafter, embodiments) will be described in detail with reference to the accompanying drawings. Note that the same number is assigned to the same element throughout the description of the embodiment.

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

(First embodiment)
FIG. 1 is a perspective view of an electrostatic spraying device 10 according to a first embodiment of the present invention. FIG. 2 is a cross-sectional view of the electrostatic spraying device 10 along the central axis of the liquid spraying unit 20.

As shown in FIGS. 1 and 2, the electrostatic spraying device 10 includes a liquid spraying unit 20, an adhesion preventing electrode 30, and a voltage applying device 50 (voltage power supply). The liquid spraying unit 20 includes a nozzle 22 that is disposed so as to face a front surface 41 that is a portion on which a liquid is applied to a flat plate-like object 40. The anti-coating electrode 30 is disposed toward the rear surface 42 which is a portion where the liquid of the object 40 is not applied. The anti-coating electrode 30 is a rod-shaped member formed from a conductive material or a semiconductive material. The voltage application device 50 applies a voltage between the object to be coated 40 and the liquid spraying unit 20 and between the object to be coated 40 and the coating preventing electrode 30. The semiconductive material is, for example, a material having a surface resistance of 10 ¹⁰ Ω or less.

In the present embodiment, the voltage application device 50 is shown as one voltage power source, but the voltage application device 50 does not have to be configured with one voltage power source. For example, the voltage application device 50 applies one power supply voltage for applying a voltage between the object to be coated 40 and the liquid spraying unit 20 and 1 for applying a voltage between the object to be coated 40 and the anti-coating electrode 30. One voltage power supply may be provided. That is, the voltage application device 50 may include two power supply voltages in total.

In the present embodiment, the electrical wiring from the voltage application device 50 is directly connected to the article 40. However, the electrical wiring from the voltage application device 50 may be connected to a terminal provided on a mounting table or the like on which the article 40 is mounted. In this case, when the object to be coated 40 is placed on a mounting table or the like, the object to be coated 40 comes into contact with the terminal thereof, so that the object to be coated 40 is electrically connected to the voltage application device 50.

Further, the electrostatic spraying device 10 has a ground wire 60 connected to an electric wiring connected to the workpiece 40 from the voltage application device 50. For this reason, the article 40 is grounded. Since the workpiece 40 may be touched by an operator, it is preferable to ground the workpiece 40 by providing a ground wire 60 from the viewpoint of safety. However, the ground wire 60 is not an essential requirement.

(Liquid spray part)
FIG. 3 is a cross-sectional view showing only the liquid spraying unit 20, and also illustrates a state where a liquid such as paint is sprayed from the liquid spraying unit 20 as will be described later.

As shown in FIG. 3, the liquid spraying part 20 includes a body part 21 formed of an insulating material, a nozzle 22, and a mandrel 23 formed of a conductive material. A liquid channel 21b having a liquid supply port 21a through which liquid is supplied is formed in the body portion 21. The nozzle 22 is provided at the tip of the body part 21. A through hole is formed inside the nozzle 22, and the through hole communicates with the liquid channel 21 b of the body portion 21. The mandrel 23 is disposed in the liquid channel 21 b of the body portion 21 and in the through hole of the nozzle 22.

The body portion 21 is provided with a hole portion 21c communicating with the liquid channel 21b in order to take out the mandrel 23 to the rear end side. A seal member 24 is provided in the hole 21c. The seal member 24 seals the gap between the body portion 21 and the mandrel 23 so that the liquid does not leak. In this embodiment, an O-ring is used as the seal member 24. However, the seal member 24 is not limited to an O-ring, and may be any seal member that can be sealed.

And, at the rear end of the mandrel 23 located on the rear end side of the body portion 21 through the hole portion 21c, a knob portion 23a and an electric wiring connection portion 23b are provided. The knob 23a is made of an insulating material. The electrical wiring connection portion 23b is provided so as to penetrate substantially the center of the knob portion 23a, and is formed of a conductive material.

As shown in FIG. 2, the electrical wiring from the voltage application apparatus 50 is connected to the electrical wiring connection part 23b. When the electrical wiring connecting portion 23b contacts the mandrel 23, the mandrel 23 and the electric wiring connecting portion 23b are electrically connected.

In this embodiment, the mandrel 23 is used as an electrode on the liquid spray unit 20 side. However, the nozzle 22 may be used as an electrode on the liquid spray unit 20 side. In this case, for example, the nozzle 22 of the liquid spray unit 20 may be formed of a conductive material, and an electrical wiring from the voltage application device 50 may be connected to the nozzle 22.

Further, as shown in FIG. 3, a female screw structure 21e for screwing and connecting the knob portion 23a is provided on the inner peripheral surface of the rear end opening 21d of the body portion 21. On the other hand, a male screw structure 23c is provided on the outer peripheral surface at the tip of the knob 23a.

Therefore, the mandrel 23 is detachably attached to the body part 21 by screwing the male thread structure 23c on the outer peripheral surface of the tip of the knob part 23a into the female thread structure 21e of the rear end opening part 21d of the body part 21. Yes. By adjusting the screwing amount of the knob 23a, the mandrel 23 can be moved in the front-rear direction, 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 for spraying the liquid of the electrostatic spraying apparatus has a fine liquid flow path in which the diameter of the through hole through which the liquid flows is small. This is presumably because a stable atomization state of the liquid cannot be obtained when the opening diameter at the tip of the nozzle from which the liquid flows is large. For example, in general, the opening diameter of the nozzle tip is less than 0.1 mm.

For this reason, as soon as the liquid dries, the opening at the tip of the nozzle is clogged. In this case, since the opening diameter is small, there is a problem that it is difficult to eliminate this clogging.

However, although the reason will be described later, the applicant of the present application has found that by using the mandrel 23, better atomization can be achieved even when the opening diameter of the tip of the nozzle is large. For this reason, the opening 22b at the tip of the nozzle 22 of the present embodiment has a large opening diameter of 0.2 mm. As a result, the frequency of clogging can be greatly reduced.

It should be noted that the opening diameter of the opening 22b of the nozzle 22 is not limited to 0.2 mm. In the embodiment 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 less likely to be clogged, and is preferably 0.1 mm or more, more preferably 0.2 mm or more in order to enable cleaning even when clogging occurs. Furthermore, it is preferable to make it larger than 0.2 mm.

On the other hand, 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 in order to stabilize atomization.

Moreover, in this embodiment, since the mandrel 23 can be moved in the front-rear direction as described above, the clogging can be eliminated by moving the mandrel 23 even if clogging occurs. Further, since the inner diameter of the through hole of the nozzle 22 is large enough to allow the mandrel 23 to be disposed, it is possible to remove the mandrel 23 and wash it by flowing a large amount of cleaning liquid.

4A and 4B are enlarged views in which the tip side of the liquid spraying unit 20 is enlarged. FIG. 4A shows a state in which the distal end surface 23d of the mandrel 23 is located rearward. FIG. 4B shows a state in which the distal end surface 23d of the mandrel 23 is located in front of the state of FIG. 4A.

As shown in FIG. 4A, the nozzle 22 has a tapered inner diameter portion (see the range W1) whose inner diameter decreases in a tapered manner toward the opening 22b. The mandrel 23 has a tapered portion (see range W2) whose outer diameter decreases toward the distal end surface 23d.

The taper angle of the tapered inner diameter portion is α. The taper angle of the tapered portion is β. 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 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. Thus, 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, as can be seen by comparing FIG. 4A and FIG. The width of the gap formed can be adjusted. As a result, the amount of liquid exiting from the opening 22b of the nozzle 22 can be adjusted.

Further, by moving the mandrel 23 further forward than in the state shown in FIG. 4B, the mandrel 23 can come into contact with the inner peripheral surface of the nozzle 22 to close the opening 22 b of the nozzle 22. Therefore, it is possible to prevent the liquid in the nozzle 22 from drying by closing the opening 22b of the nozzle 22 with the mandrel 23 in a state where no liquid such as paint is sprayed. As a result, clogging of the nozzle 22 can be suppressed.

Next, referring to FIG. 3, first, a state where the liquid is sprayed from the liquid spraying unit 20 will be described, and then the liquid is applied to the rear surface 42 of the article 40 where the liquid is not applied. A description will be given of the fact that the liquid can be applied to the front surface 41, which is the portion where the liquid is applied, while preventing the liquid from being applied.

The liquid supplied to the liquid supply port 21a of the body part 21 is supplied to the tip end side of the nozzle 22, and is applied between the workpiece 40 and the mandrel 23 by the voltage application device 50 (see FIGS. 1 and 2). Due to the electrostatic force accompanying the applied voltage, it is pulled forward and detaches and atomizes forward.

More specifically, in the voltage application by the voltage application device 50, the potential of the object to be coated 40 is set to the reference potential (in this embodiment, the object 40 is grounded, so the reference potential is 0V). Sometimes, the electric potential of the liquid spray unit 20 (more precisely, the electric potential of the mandrel 23) is set to a first electric potential different from the reference electric potential. The first potential is set such that the potential difference between the reference potential and the first potential is a potential difference that can generate an electrostatic force that can detach the liquid from the nozzle 22 in a charged state. For this reason, the liquid supplied to the front end side of the nozzle 22 is pulled forward by the electrostatic force, and is separated and atomized forward.

In addition, the supply of the liquid should just supply the liquid of the part lost from the liquid spraying part 20 by being consumed by spraying one by one. In other words, it is not necessary to be pumped and supplied at such a pressure that the liquid is ejected from the opening 22b of the nozzle 22 (more precisely, the gap between the opening 22b and the mandrel 23). In the state where the liquid is ejected vigorously, it may happen that the atomization cannot be performed.

The state where the liquid is detached 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 to the front end surface 23d of the mandrel 23 and the front end edge 22a of the nozzle 22. The electrostatic force pulling is balanced. As a result, as shown in FIG. 3, a tailor cone 80 is formed in which the liquid supplied to the tip side of the nozzle 22 has a conical shape at the tip.

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

The liquid to be sprayed, that is, the liquid that has separated from the nozzle 22 into liquid particles has a drastic increase in the area in contact with air as compared to the state before the separation. For this reason, the vaporization of the solvent is promoted, and with the vaporization of the solvent, the distance between the charged electrons approaches, and electrostatic repulsion (electrostatic explosion) occurs. As a result, the liquid particles break up into small-sized liquid particles.

When this splitting occurs, the surface area in contact with air will increase more than before splitting. For this reason, vaporization of the solvent is promoted, and electrostatic explosion occurs as described above. As a result, the liquid particles break up into small-sized liquid particles. The liquid is atomized by repeating such electrostatic explosion.

Here, in this embodiment, a mandrel 23 is provided in the nozzle 22. Assuming that the mandrel 23 is not provided as in the conventional electrostatic spraying device, the portion to which the liquid can adhere is only the tip edge 22a of the nozzle 22.

If the opening diameter of the opening 22b of the nozzle 22 is increased in such a state, the liquid can easily adhere to the top, bottom, left, and right of the nozzle 22, for example, because the portion to which the liquid can adhere is only the tip edge 22a. Or a beautiful tailor cone 80 cannot be formed. In some cases, the tailor cone 80 itself cannot be maintained. For this reason, it is assumed that the stability of the liquid particles detaching from the nozzle 22 (stability such as particle size, number, and charged state) cannot be obtained, and as a result, stable atomization of the liquid cannot be performed. .

On the other hand, in the present embodiment, the mandrel 23 is disposed in the nozzle 22, and the liquid adheres not only to the tip edge portion 22 a of the nozzle 22 but also to the tip surface 23 d of the mandrel 23. Therefore, even if the opening diameter of the opening 22b of the nozzle 22 is large, the tip end surface 23d of the mandrel 23 to which the liquid can adhere is present at the center of the opening 22b, so that a stable tailor cone 80 can be formed. It is thought that stable atomization is possible.

It should be noted that if the tip surface 23d of the mandrel 23 protrudes too far forward from the tip edge portion 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 exiting the nozzle 22. On the other hand, if the distal end surface 23d of the mandrel 23 is excessively retracted backward from the distal end surface of the opening 22b of the nozzle 22, a portion where the liquid can adhere is in the same state as if there is no central portion of the opening 22b.

From this, the position of the tip surface 23d of the mandrel 23 is in the front-rear direction along the central axis of the mandrel 23 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 this embodiment, the opening diameter of the opening 22b of the nozzle 22 is 0.2 mm. For this reason, when the electrostatic force does not act, the liquid comes out from the opening 22b of the nozzle 22 so as to be a hemisphere having a diameter of about 0.2 mm at the tip of the nozzle 22.

Then, the tip of the mandrel 23 reaches the vicinity of the opening 22b of the nozzle 22 so that a conical tailor cone 80 can be formed by an electric field (electrostatic force) acting on the liquid coming out of the tip of the nozzle 22. It should be near. For this reason, it is preferable that the tip of the mandrel 23 be positioned within 2 mm forward (in the direction of exit) from the tip surface of the opening 22 b of the nozzle 22. On the other hand, it is preferable that the tip of the mandrel 23 is located within 2 mm behind (in the retracting direction) from the tip surface of the opening 22b of the nozzle 22 so as to affect the adhesion of the liquid.

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. For this reason, the opening diameter of the opening part 22b of the nozzle 22 can be made into a large opening diameter which can suppress clogging. 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 distal end surface 23d of the distal end of the mandrel 23 is formed in a flat plane. However, the distal end surface 23d is not necessarily a flat flat surface, and may have a shape that can contribute to the stable formation of the tailor cone 80. For example, the tip surface 23d may be formed as a curved surface that protrudes toward the front side, such as an R shape.

The liquid sprayed from the liquid spray unit 20 (nozzle 22) in this way is atomized while repeating electrostatic explosion. Since the atomized liquid is in a charged state, it is attracted by the electrostatic force by the voltage application device 50 to the object 40 that acts as a different polarity with respect to the liquid spraying unit 20, and is applied to the object 40. Will do.

Here, as described above, the electrostatic spraying device 10 according to the present embodiment prevents the application toward the rear surface 42, which is a portion to which the liquid of the object 40 is not applied, as shown in FIGS. An electrode 30 is disposed.

As shown in FIGS. 1 and 2, an electrical wiring directly branched from the electrical wiring connecting the voltage application device 50 and the liquid spray unit 20 is connected to the coating preventing electrode 30. For this reason, the application preventing electrode 30 has a second potential different from the reference potential, similar to the liquid spray unit 20, when the potential of the article 40 is set as the reference potential. Moreover, the second electric potential has the same polarity direction as the first electric potential of the liquid spray unit 20.

In the present embodiment, the electrical wiring directly branched from the electrical wiring that connects the voltage application device 50 and the liquid spray unit 20 is connected to the anti-coating electrode 30 without interposing a resistor or the like. . For this reason, the 1st electric potential of the liquid spraying part 20 and the 2nd electric potential of the adhesion preventing electrode 30 are substantially the same electric potential.

FIG. 5 shows a state of an electric field (electric field when a voltage is applied between the object to be coated 40 and the liquid spray unit 20 and between the object to be coated 40 and the anti-coating electrode 30 by the voltage application device 50. FIG. FIG. 5 is a side view seen from the direction in which the side surface of the liquid spraying unit 20 can be seen. In FIG. 5, the voltage application device 50 and the electrical wiring are not shown.

As can be seen from FIG. 5, an electric field generated between the object to be coated 40 and the coating preventing electrode 30 exists on the rear surface 42 side of the object to be coated 40. The electric field generated between the two sides does not go around to the rear face 42 side. Note that an electric field similar to that in FIG.

That is, since the electric field between the liquid spraying unit 20 and the object to be coated 40 is generated only between the liquid spraying unit 20 and the front surface 41, the liquid sprayed from the liquid spraying unit 20 is the object to be coated. Thus, the wire 40 is drawn to the front surface 41 of the object to be coated 40 and does not wrap around the rear surface 42 side of the object 40 and is applied to the front surface 41 of the object to be coated 40.

On the other hand, when the anti-coating electrode 30 is not provided, an electric field is also generated between the liquid spray unit 20 and the rear surface 42. For this reason, of the liquid sprayed from the liquid spraying unit 20, the liquid sprayed at a position offset from the coating object 40 wraps around the rear surface 42 side of the coating object 40 and is applied. In the case of the present embodiment, since the occurrence of such wraparound coating can be suppressed, it is not necessary to provide a mask on the rear surface 42 of the article 40 to be coated.

(Second Embodiment)
FIG. 6 is a perspective view showing the electrostatic spraying device 10 of the second embodiment. Many of the configurations of the electrostatic spraying device 10 of the second embodiment are the same as those of the first embodiment. For this reason, below, a different point from 1st Embodiment is mainly demonstrated and description may be abbreviate | omitted about the part similar to 1st Embodiment.
The second embodiment is different from the first embodiment in that the article 40 has a quadrangular prism shape, but is similar to the first embodiment in that a liquid is applied to the front surface 41 of the article 40. It is. In the second embodiment, the left and right side surfaces 43 and 44, not the rear surface 42, are mainly portions to which no liquid is applied, so that the two anti-coating electrodes 30 are directed toward the portion where the liquid is not applied. Is different from the first embodiment.

FIG. 7 shows a state of an electric field when a voltage is applied between the object 40 and the liquid spraying unit 20 and between the object 40 and the two anti-coating electrodes 30 by the voltage application device 50. It is the figure which showed (direction of an electric field). FIG. 7 is a top view seen from the direction in which the upper side of the liquid spray unit 20 can be seen. In FIG. 7, the voltage application device 50 and the electrical wiring are not shown.

As can be seen from FIG. 7, an electric field is generated between the object to be coated 40 and the anti-coating electrode 30, so that the left and right side surfaces of the object to be coated 40 to which the anti-coating electrode 30 is directed are also shown. The electric field generated between 43 and 44 and the liquid spraying part 20 does not go around to the side surfaces 43 and 44 side. For this reason, even if a mask is not provided on the left and right side surfaces 43 and 44 of the article 40, the liquid sprayed from the liquid spraying unit 20 does not adhere to the left and right side faces 43 and 44 of the article 40. . In addition, when it is desired to prevent the liquid from being applied to the upper and lower surfaces of the object to be coated 40, an additional anti-coating electrode 30 may be provided toward the upper and lower surfaces.

As described above, when liquid is mainly applied to the front surface 41 of the object to be coated 40, a straight line (see the Z axis in FIG. 7) that connects the tip of the nozzle 22 and the object to be coated 40 with the shortest distance. When a plane (see the front surface 41) orthogonal to the straight line (see the Z-axis in FIG. 7) is defined at a point where it crosses the coating 40, an appropriate position on the opposite side of the liquid spraying unit 20 with respect to the plane (for example, It is preferable that the coating preventing electrode 30 is positioned at a position facing the upper, lower, left, or right surface of the article 40 or a position facing the rear surface 42 as in the first embodiment.

In particular, when the liquid is not applied to the rear surface 42 of the flat plate-like object 40 as in the first embodiment, the anti-coating electrode 30 is opposite to the liquid spray unit 20 with respect to the object 40. It is preferable to be located in the position.

(Third embodiment)
FIG. 8 is a perspective view showing the electrostatic spraying device 10 of the third embodiment. The third embodiment is different from the first embodiment in that a cylindrical object 40 is used instead of the flat object 40 of the first embodiment, and other points are different from those of the first embodiment. It is the same. By doing so, it is possible to apply the liquid to the half surface of the cylindrical object 40 facing the liquid spraying part 20 side and not to apply the liquid to the remaining half surface. is there.

In the embodiment described so far, the case where the second potential that is the potential of the anti-coating electrode 30 is substantially the same as the first potential that is the potential of the liquid spray unit 20 has been described. Note that the second potential is not necessarily the same as the first potential.

If the polarity of the first potential and the second potential is the same when the potential of the object to be coated 40 is the reference potential, what is the second potential that is the potential of the coating preventing electrode 30? The potential may be changed according to the range where the liquid is not desired to be applied.

For example, if a variable resistor is added in the middle of the electrical wiring connected to the anti-coating electrode 30, it is possible to change the second potential by changing the resistance value of this variable resistor. If the second potential is brought close to the reference potential that is the potential of the object to be coated 40, the electric field generated between the coating preventing electrode 30 and the object to be coated 40 becomes weak, so the range in which no liquid is applied is reduced. can do.

On the contrary, if the second potential is separated from the reference potential which is the potential of the object 40, the electric field generated between the anti-coating electrode 30 and the object 40 becomes stronger. The range in which the liquid is not applied can be increased.

However, when the directions of the polarities of the first potential and the second potential are opposite to each other, this means that the anti-coating electrode 30 has a different polarity with respect to the liquid spray unit 20 that is the first potential. means. In this case, an electric field is generated between the application preventing electrode 30 and the liquid spraying unit 20, and the application preventing electrode 30 becomes a target to which the liquid sprayed from the liquid spraying unit 20 is applied. For this reason, as described above, when the potential of the workpiece 40 is set to the reference potential, the polarities of the first potential and the second potential need to be the same.

(Fourth embodiment)
FIG. 9 is a perspective view showing the electrostatic spraying device 10 of the fourth embodiment. In the fourth embodiment, in addition to the configuration shown in FIG. 8, the electrostatic spraying device 10 includes a proximity electrode holder 71 fixed to the outer periphery of the nozzle 22, a proximity electrode 70 disposed in the vicinity of the nozzle 22, The point which comprises is mainly different from 3rd Embodiment. The proximity electrode holder 71 is made of an insulating material.

Application of a voltage to the proximity electrode 70 by the voltage application device 50 is performed so that the potential of the proximity electrode 70 becomes the third potential. The third potential is a potential between the reference potential that is the potential of the article to be coated 40 and the first potential that is the potential of the liquid spray unit 20. The third potential is set such that the potential difference between the first potential and the third potential is a potential difference that can generate an electrostatic force that causes the liquid to leave the nozzle 22 in a charged state.

For example, as shown in FIG. 9, the potential of the proximity electrode 70 (third potential) is obtained by dividing the voltage applied between the object to be coated 40 and the liquid spraying part 20 with the resistance R, The reference potential that is the potential of the object 40 and the first potential that is the potential of the liquid spray unit 20 are set approximately in the middle.

If such a proximity electrode 70 is provided, the separation / atomization of the liquid from the nozzle 22 is mainly performed between the proximity electrode 70 and the liquid spraying unit 20. For this reason, the state which atomized can be maintained even in the state where the to-be-coated object 40 is not arrange | positioned.

Immediately after the start of atomization, the state of atomization may not be stable. However, according to this configuration, the object to be coated 40 is conveyed to a position where the liquid is sprayed by a conveyor or the like at a timing when the atomization is stable. be able to. In other words, it is possible to avoid that the liquid whose atomization state is not stable immediately after the start of atomization is applied to the article 40. Therefore, it is possible to suppress the occurrence of coating unevenness.

As mentioned above, although the electrostatic spraying apparatus of this invention has been demonstrated based on specific embodiment, this invention is not limited to said specific embodiment. For example, in the above-described embodiment, the anti-coating electrode 30 is arranged toward the portion of the article 40 to which the liquid is not applied. However, even if the anti-coating electrode 30 does not face the portion of the object 40 to which the liquid is not applied, the anti-coating electrode 30 does not apply the anti-coating electrode 30 and the liquid of the object 40 to be applied. Since an electric field can be generated between the two portions, liquid application can be prevented.

For this reason, the anti-coating electrode 30 can be disposed in any orientation that can generate an electric field between the anti-coating electrode 30 and the portion of the article 40 to which no liquid is applied. That is, it is not an indispensable requirement that the anti-coating electrode 30 is arranged toward a portion of the article 40 to which the liquid is not applied.

As described above, the present invention is not limited to the above-described embodiment, and forms appropriately modified and improved are also included in the technical scope of the present invention. This will be apparent to those skilled in the art from the claims. Further, in a range where at least a part of the above-described problems can be solved, or in a range where at least a part of the above-described effects can be achieved, any combination or omission of each component described in the claims and the specification Is possible.

DESCRIPTION OF SYMBOLS 10 Electrostatic spraying device 20 Liquid spray part 21 Body part 21a Liquid supply port 21b Liquid flow path 21c Hole part 21d Rear end opening part 21e Female screw structure 22 Nozzle 22a Tip edge part 22b Opening part 23 Mandrel 23a Knob part 23b Electric wiring connection Portion 23c Male screw structure 23d Front end surface 24 Seal member 30 Anti-coating electrode 40 Object 41 Front surface 42 Rear surface 43, 44 Side surface 50 Voltage application device 60 Ground wire 70 Proximity electrode 71 Proximity electrode holder 80 Tailor cone

Claims (7)

An electrostatic spraying device for applying a liquid to an object to be coated,
A voltage application device;
A liquid spraying section having a nozzle for separating the liquid in a charged state using electrostatic force generated by a voltage application device;
An anti-coating electrode, and an anti-coating electrode that generates an electric field between the anti-coating electrode and a portion of the article to which the liquid is not applied; and
With
In the voltage application device, when the potential of the object to be coated is set as a reference potential, the potential of the liquid spray portion becomes a first potential different from the reference potential, and the potential of the anti-coating electrode Is configured to apply a voltage such that is at a second potential,
The electrostatic spraying device, wherein the second potential is a potential different from the reference potential, and a polarity direction is the same as the first potential. The electrostatic spray device according to claim 1,
The anti-coating electrode is opposite to the liquid spraying portion with respect to a virtual plane orthogonal to the straight line at a point where a straight line connecting the tip of the nozzle and the object to be coated with the shortest distance intersects the object to be coated. Located in the electrostatic spraying device. The electrostatic spray device according to claim 1 or 2,
The anti-coating electrode is a rod-shaped member formed of a conductive material or a semiconductive material. The electrostatic spray device according to any one of claims 1 to 3,
The said anti-coating electrode is an electrostatic spraying device located in the opposite side to the said liquid spraying part with respect to the said to-be-coated article. The electrostatic spraying device according to any one of claims 1 to 4,
The voltage applying device applies an electric voltage between the object to be coated and the liquid spraying unit and between the object to be coated and the anti-coating electrode. The electrostatic spray device according to any one of claims 1 to 5,
The electrostatic spraying device, wherein the first potential and the second potential are substantially the same potential. The electrostatic spray device according to any one of claims 1 to 6,
A proximity electrode disposed in the vicinity of the nozzle;
The voltage application device is configured to apply a voltage so that a potential of the proximity electrode becomes a third potential between the reference potential and the first potential,
The third potential is set such that a potential difference between the first potential and the third potential is a potential difference that can generate an electrostatic force that causes the liquid to be detached from the nozzle in a charged state. apparatus.

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