JP2024019031A - electrostatic spray device - Google Patents

Abstract

To provide an electrostatic atomizer which can prevent formation of an unintended coating pattern.SOLUTION: An electrostatic atomizer 10 by an electro-spray method for applying a voltage between a liquid atomizing part 20 having a nozzle 22 for atomizing liquid and a different electrode part 40 which is a different electrode from the liquid atomizing part 20, and thereby atomizing the liquid toward the different electrode part 40 from the nozzle 22 includes the liquid atomizing part 20, voltage application means 50 for applying a voltage between the liquid atomizing part 20 and the different electrode part 40, and thereby generating electrostatic force of detaching the liquid in a charged state from the nozzle 22 and atomizing the liquid, and a shielding member 100 for covering at least a part of a tip outer peripheral surface of the nozzle 22 and shielding action of electrostatic force to a covered part, wherein a gap F in a vertical direction to a shaft line LN of the nozzle 22 is provided between an inside surface 100b facing the tip outer peripheral surface of the nozzle 22 of the shielding member 100 and the tip outer peripheral surface of the nozzle 22.SELECTED DRAWING: Figure 1

Description

The present disclosure relates to electrostatic spray devices.

Patent Document 1 discloses an electrostatic spraying device in which a charged liquid is separated from the tip of a liquid spraying section, and the separated liquid is electrostatically exploded and atomized to be atomized and coated onto an object to be coated. There is. This electrostatic spraying device includes a voltage applying means for generating an electrostatic force to separate the charged liquid from the tip of the liquid spraying section. Further, the liquid spray section includes a nozzle having an opening that serves as a liquid outlet, and a shaft movably disposed within the nozzle. As a result, it is disclosed that this electrostatic spraying device can perform stable atomization even if the opening diameter of the nozzle is increased, and clogging is less likely to occur.

Japanese Patent Application Publication No. 2016-131961

However, in the above-mentioned conventional technology, a portion of the liquid that has not separated from the tip of the liquid spray section may be transmitted from the tip of the nozzle to the outer circumferential surface of the tip of the nozzle due to electrostatic force, forming a liquid pool. If an electrostatic force acts on the tip of this liquid pool, the liquid may separate from the liquid pool and become atomized, and the atomized liquid may form an unintended coating pattern on the surface of the object to be coated.

Therefore, an object of the present disclosure is to provide an electrostatic spraying device that can prevent formation of an unintended coating pattern.

The present invention is understood as follows in order to achieve the above object.
(1) The electrostatic spraying device of the present invention is configured to apply a voltage between a liquid spraying section including a nozzle for spraying liquid and a different polarity section having a different polarity with respect to the liquid spraying section. An electrostatic spraying device using an electrospray method that sprays the liquid toward a different polarity part, the electrostatic spraying apparatus comprising: applying a voltage between the liquid spraying part and the liquid spraying part and the different polarity part; Voltage application means for generating an electrostatic force that causes the liquid to leave the nozzle in a charged state and atomize it; and a voltage applying means that covers at least a portion of the outer peripheral surface of the tip of the nozzle to shield the action of the electrostatic force on the covered portion. a shielding member, and a gap is provided in a direction perpendicular to the axis of the nozzle between an inner surface of the shielding member that faces the outer circumferential surface of the tip of the nozzle and an outer circumferential surface of the tip of the nozzle.
(2) In the above (1), the tip of the shielding member is arranged behind the tip of the nozzle.
(3) In (2) above, the tip of the shielding member is disposed at least 1 mm and no more than 5 mm behind the tip of the nozzle.
(4) In (1) above, the gap between the inner surface of the shielding member and the outer peripheral surface of the tip of the nozzle is 0.2 mm or more and 5 mm or less in a direction perpendicular to the axis of the nozzle.
(5) In (1) or (2) above, the shielding member covers the entire circumference of the outer peripheral surface of the tip of the nozzle.
(6) In the above (1), a cleaning mechanism is provided for cleaning to remove the liquid accumulated in the gap, and the cleaning mechanism is configured to be able to supply the cleaning liquid to the gap.

According to the present disclosure, it is possible to provide an electrostatic spraying device that can prevent formation of an unintended coating pattern.

1 is a sectional view showing the overall configuration of an electrostatic spraying device according to a first embodiment of the present invention. FIG. 2 is an exploded cross-sectional view showing a liquid spray section and a shielding member according to the first embodiment of the present invention. FIG. 2 is a partially enlarged cross-sectional view of the distal end side of the liquid spray unit according to the first embodiment of the present invention, and (a) is a diagram when the distal end surface of the mandrel is located behind the distal end of the nozzle; (b) is a diagram in which the tip end surface of the mandrel is located further forward than in the state of (a). FIG. 3 is a cross-sectional view showing a state in which liquid is sprayed from the liquid spray unit according to the first embodiment of the present invention. FIG. 2 is a perspective view showing an application pattern of a liquid sprayed from a liquid spraying section of a conventional electrostatic spraying device. FIG. 2 is a side view showing an application pattern of a liquid sprayed from a liquid spraying section of a conventional electrostatic spraying device. FIG. 3 is a rear view showing an application pattern of liquid sprayed from a liquid spraying section of a conventional electrostatic spraying device. FIG. 2 is a perspective view showing an application pattern of a liquid sprayed from a liquid spraying section of the electrostatic spraying device according to the first embodiment of the present invention. FIG. 3 is a side view showing an application pattern of liquid sprayed from the liquid spraying section of the electrostatic spraying device according to the first embodiment of the present invention. FIG. 3 is a rear view showing an application pattern of liquid sprayed from the liquid spraying section of the electrostatic spraying device according to the first embodiment of the present invention. FIG. 7 is a cross-sectional view showing a liquid spray section and a shielding member according to a second embodiment of the present invention. FIG. 7 is a cross-sectional view showing a modification of the liquid spray section and the shielding member according to the second embodiment of the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, modes for carrying out the present invention (hereinafter referred to as embodiments) will be described in detail with reference to the accompanying drawings. Note that the same elements are given the same numbers throughout the description of the embodiments.
Unless otherwise specified, expressions such as "tip" and "front" refer to the side of each member in the direction of liquid spraying, and "rear" and "rear" ” and the like indicate the side opposite to the direction in which the liquid is sprayed in each member, etc.

The electrostatic spraying device according to the present invention applies a voltage between a liquid spraying section that includes a nozzle that sprays liquid and a different polarity section that has a different polarity with respect to the liquid spraying section. This is an electrostatic spraying device that uses the electrospray method to spray liquid toward the target.

<First embodiment>
FIG. 1 is a sectional view showing the overall configuration of an electrostatic spraying device 10 according to a first embodiment of the present invention.
As shown in FIG. 1, the electrostatic spraying device 10 applies a voltage between a liquid spraying section 20 that includes a nozzle 22 that sprays liquid and a different polarity section 40 that has a different polarity with respect to the liquid spraying section 20. In this way, the configuration is such that the liquid is sprayed from the nozzle 22 toward the different polarity portion 40 . Specifically, the electrostatic spraying device 10 includes a liquid spraying section 20, a voltage applying means (voltage power source) 50, and a shielding member 100. The electrostatic spraying device 10 is configured to be able to apply a voltage between the liquid spraying section 20 and the different polarity section 40 using the voltage applying means 50.

(Liquid spray part)
FIG. 2 is an exploded cross-sectional view showing the liquid spray section 20 and the shielding member 100 separated.
As shown in FIG. 2, the liquid spraying section 20 includes a body 21 made of an insulating material, a nozzle 22 disposed at the tip of the body 21, and a shaft 23 made of a conductive material. A liquid flow path 21b through which liquid flows is formed in the body portion 21. The liquid channel 21b has a liquid supply port 21a that allows liquid to be supplied to the liquid channel 21b. The nozzle 22 includes an internal space that communicates with the liquid flow path 21b of the body portion 21, and is configured to be able to flow liquid into the internal space. The mandrel 23 is arranged from the inside of the liquid flow path 21b of the body part 21 to the inside of the nozzle 22.

The body portion 21 is provided with a hole 21c that communicates with the liquid flow path 21b in order to take out the mandrel 23 to the rear end side. A sealing member 24 is provided in the hole 21c to seal the gap between the hole 21c and the mandrel 23 to prevent liquid from leaking.
Note that in the first embodiment, an O-ring is used as the sealing member 24, but the sealing member 24 is not limited to an O-ring, and any other material capable of sealing may be used.

A knob 23a made of an insulating material is provided at the rear end of the mandrel 23, which is located on the rear end side of the body section 21 through the hole 21c. Further, at the rear end of the mandrel 23, an electrical wiring connection part 23b made of a conductive material is provided so as to pass through approximately the center of the knob part 23a.

As shown in FIG. 1, the electrical wiring from the voltage application means 50 is connected to the electrical wiring connection portion 23b.
As shown in FIG. 2, the electric wiring connecting part 23b contacts the mandrel 23, so that the mandrel 23 and the electric wiring connecting part 23b are electrically connected.

Furthermore, a female screw structure 21e for threadingly connecting the knob 23a is provided on the inner circumferential surface of the rear end opening 21d, which is the opening on the rear end side of the body part 21. On the other hand, a male screw structure 23c is provided on the outer peripheral surface of the tip of the knob 23a.

Therefore, the mandrel 23 is removably attached to the body part 21 by screwing the male thread structure 23c on the outer peripheral surface of the distal end of the knob 23a into the female thread structure 21e of the rear end opening 21d of the body part 21.
Moreover, since the mandrel 23 moves in the front-rear direction by adjusting the amount of engagement of the knob 23a, the position of the distal end surface 23d of the mandrel 23 can be adjusted in the front-rear direction.

Generally, in an electrostatic spraying device, a nozzle that sprays a liquid has an internal space through which the liquid flows, which has a relatively small diameter, so that the internal space forms a fine liquid flow path.
This is presumed to be because if the opening diameter of the nozzle tip from which the liquid flows out is large, a stable atomization state of the liquid cannot be obtained.
For example, the opening diameter of the nozzle tip is generally less than 0.1 mm.

Therefore, as soon as the liquid dries, the opening at the tip of the nozzle becomes clogged. Since the diameter of this opening is small, there is a problem in that it is difficult to eliminate this clogging.

However, for reasons that will be explained later, it has been found that by using the mandrel 23, better atomization can be achieved even if the opening diameter of the nozzle tip is made larger than in the past. Therefore, in the first embodiment, the opening diameter of the opening 22b at the tip of the nozzle 22 can be made relatively large (for example, 0.2 mm).
As a result, the frequency at which clogging occurs can be significantly reduced.

Note that the opening diameter of the opening 22b of the nozzle 22 is not limited to 0.2 mm, and in the case where the mandrel 23 is used, there is no problem even if the opening diameter is about 1 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, considering that clogging is unlikely to occur and cleaning can be done even if clogging occurs. More preferably, it is 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 even more preferably 0.5 mm or less.

Furthermore, in the first embodiment, as described above, since the mandrel 23 can be moved in the front-rear direction, even if clogging occurs, the clogging can be cleared by moving the mandrel 23.
Furthermore, since the inner diameter of the internal space of the nozzle 22 can be made large enough to accommodate the mandrel 23, it is also possible to remove the mandrel 23 and flush a large amount of cleaning liquid for cleaning.

FIG. 3 is an enlarged view of the distal end side of the liquid spraying section 20, and FIG. ) is a case where the tip end surface 23d of the mandrel 23 is located further forward than in the state shown in FIG. 3(a).

As shown in FIG. 3A, the nozzle 22 has a tapered inner diameter portion (see range A) where the inner diameter tapers toward the opening 22b and has a taper angle α. Further, the mandrel 23 has a tapered portion (see range B) where the outer diameter decreases toward the distal end surface 23d at a taper angle of 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 tip end surface 23d of the mandrel 23 is smaller than the opening diameter of the opening 22b of the nozzle 22. On the other hand, the diameter of the tapered portion of the mandrel 23 gradually increases toward the rear end side. The tapered portion of the mandrel 23 is formed to have a diameter larger than the opening diameter of the opening 22b of the nozzle 22.

By forming the tips of the nozzle 22 and the mandrel 23 as described above, as can be seen by comparing FIGS. The width of the gap formed can be adjusted. Thereby, the amount of liquid coming out of 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. 3(b), the mandrel 23 can be brought into contact with the inner circumferential surface of the nozzle 22. This allows the mandrel 23 to close the opening 22b of the nozzle 22.
Therefore, when the liquid is not being sprayed, the opening 22b of the nozzle 22 can be closed with the mandrel 23 to prevent the liquid in the nozzle 22 from drying out. Thereby, clogging of the nozzle 22 can be suppressed.

(Different pole part 40)
In the first embodiment, the different polarity portion 40 in FIG. 1 is the object to be coated. Specifically, the electrical wiring on the side opposite to that connected to the mandrel 23 is connected to the object to be coated, so that the object to be coated itself has a different polarity with respect to the liquid spray section 20 .
Further, the object to be coated, which becomes the different polarity portion 40, is grounded by a grounding means 80.
Although this grounding means 80 is not an essential requirement, it is preferable to provide it from the viewpoint of safety since the worker may come into contact with the object to be coated.

In the first embodiment, the electrical wiring from the voltage application means 50 is connected to the object to be coated in order to make the object to be coated the different polarity portion 40 . However, in order to make the object to be coated the different polarity portion 40, it is not necessary to directly connect the electrical wiring to the object to be coated.
For example, when the object to be coated is transported by a transport device or the like to a position where a liquid such as paint is applied, the voltage applying means 50 is applied to the mounting portion of the transport device on which the object to be painted is placed. The object to be coated may be electrically connected to the voltage applying means 50 via the mounting section by connecting the electrical wiring.

(shielding member)
As shown in FIG. 1, an electrostatic spraying device 10 according to a first embodiment of the present invention includes a shielding member 100. As shown in FIG. This shielding member 100 covers at least a portion of the outer peripheral surface of the tip of the nozzle 22. Thereby, the shielding member 100 shields the covered portion from the action of electrostatic force. Further, an inner surface 100b, which is an inner surface of the shielding member 100, is arranged to face the outer circumferential surface of the tip of the nozzle 22. A gap F in a direction perpendicular to the axis LN of the nozzle 22 is provided between the inner surface 100b of the shielding member 100 and the outer peripheral surface of the tip of the nozzle 22.

As shown in FIG. 2, the shielding member 100 is formed into a cylindrical shape around an axis LN extending in the length direction of the nozzle 22. As shown in FIG. Moreover, the shielding member 100 includes openings at both ends (specifically, the front end 100a and the rear end 100c) in the direction of the axis LN. The opening on the rear end portion 100c side is formed in a tapered shape so that the rear inner peripheral portion 100d, which is the inner peripheral portion thereof, becomes wider toward the rear. Further, the tip outer peripheral portion 21g of the body portion 21 has a tapered shape that tapers toward the front. Then, the shielding member 100 is attached to the liquid spraying section 20 by fitting the rear inner peripheral portion 100d of the shielding member 100 with the outer peripheral portion 21g of the distal end of the body portion 21 from the outside. Note that the shielding member 100 is not limited to being directly attached to the body section 21. For example, the shielding member 100 may be arranged to cover the outer peripheral surface of the tip of the nozzle 22 using an arm structure or the like.

As shown in FIGS. 1 and 4, the shielding member 100 may have a distal end portion 100a, which is the distal end of the shielding member 100, located behind the distal end of the nozzle 22.

As shown in FIGS. 1, 4, etc., the shielding member 100 is formed in a cylindrical shape, but is not limited to this. For example, the portion of the shielding member 100 that covers the outer circumferential surface of the tip of the nozzle 22 may be formed into a cylindrical shape like a spring pin having an axial longitudinal groove (gap). That is, the shielding member 100 may cover the entire circumference of the outer circumferential surface of the tip of the nozzle 22, or may cover a part of the outer circumferential surface of the tip of the nozzle 22.

Further, the shielding member 100 may be made of a conductive material or an insulating material.

FIG. 4 is a sectional view showing a state in which liquid is sprayed from the liquid spraying section 20 of the electrostatic spraying device 10 according to the first embodiment of the present invention.
While explaining the state of spraying a liquid using the electrostatic spraying device 10 of the first embodiment having the above-described configuration using FIG. 4, the configuration of the electrostatic spraying device 10 of the first embodiment will be further explained. A detailed explanation will be provided regarding such matters.

In FIGS. 1 and 4, the liquid coming out of the nozzle 22 is pulled by the electrostatic force generated by the voltage applied by the voltage applying means 50 between the liquid spraying part 20 and the different polarity part 40 (subject 40). . At this time, the electrostatic force that pulls the liquid balances the adhesion force due to surface tension and viscosity to the tip surface 23d of the mandrel 23 and the tip outer peripheral edge 22a of the nozzle 22. In this way, the liquid supplied to the tip side of the nozzle 22 becomes a Taylor cone 60 having a conical shape at its tip, as shown in FIG.

The Taylor cone 60 is formed by separation of positive and 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 into a conical shape.
Then, the liquid is pulled straight from the tip of the Taylor cone 60 by electrostatic force, and then electrostatically explodes.

The forward pulling force leading to this electrostatic explosion becomes the inertial force of the sprayed liquid. Further, as a result of interactions such as spreading force (repulsive force) during electrostatic explosion and pulling force due to electrostatic force, the liquid is sprayed forward.

The sprayed liquid, that is, the liquid that has separated from the nozzle 22 in a charged state and turned into liquid particles, has a dramatically larger area in contact with the air than before separation, so that the vaporization of the solvent is prevented. promoted. As the solvent evaporates, the distance between the charged electrons becomes closer, electrostatic repulsion (electrostatic explosion) occurs, and the liquid particles split into smaller liquid particles. When this splitting occurs, the surface area that comes into contact with air increases compared to before splitting, which promotes vaporization of the solvent. Then, the liquid explodes again due to electrostatic force and splits into smaller liquid particles. By repeating such electrostatic explosions, the liquid is atomized.

Note that the liquid may be supplied to the liquid spraying section 20 as long as the amount of liquid that is lost from the liquid spraying section 20 due to being consumed by spraying is sequentially supplied. That is, the liquid supplied to the liquid spraying section 20 is supplied under pressure such that the liquid is sprayed from the opening 22b of the nozzle 22 (more precisely, the gap between the opening 22b and the mandrel 23). There's no need. If the liquid is vigorously injected by such pressure-feeding, it may not be possible to atomize the liquid well.

Here, in the first embodiment, the mandrel 23 is arranged within the nozzle 22.
If the mandrel 23 were not provided as in a conventional electrostatic spraying device, the only part to which the liquid could adhere would be the outer peripheral edge 22a of the tip of the nozzle 22.
In such a state, if the opening diameter of the opening 22b of the nozzle 22 is increased, for example, the liquid tends to fluctuate in the vertical and horizontal directions of the nozzle 22, making it impossible to form a well-shaped Taylor cone 60, or causing the Taylor cone 60 itself to become unstable. It may become impossible to maintain. For this reason, the stability of the liquid particles leaving the nozzle 22 (stability of particle size, number, charging state, etc.) cannot be achieved. As a result, it is presumed that stable atomization of the liquid becomes impossible.

On the other hand, in the first embodiment, the mandrel 23 is arranged within the nozzle 22. Therefore, the liquid adheres not only to the outer peripheral edge 22a of the tip of the nozzle 22 but also to the tip surface 23d of the mandrel 23.
That is, even if the opening diameter of the opening 22b of the nozzle 22 is formed relatively large, the tip surface 23d of the mandrel 23 to which the liquid can adhere exists at the center of the opening 22b. Therefore, it is considered that a stable Taylor cone 60 can be formed and stable atomization of the liquid can be performed.

Note that if the tip surface 23d of the mandrel 23 protrudes 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), it becomes difficult for an electric field to act on the liquid coming out of the nozzle 22. On the other hand, if the distal end surface 23d of the mandrel 23 is retracted too far backward from the distal end surface of the opening 22b of the nozzle 22, it will be in the same state that there is no part at the center of the opening 22b to which liquid can adhere.

From this, the position of the distal end surface 23d of the mandrel 23 is determined in the front-rear direction along the longitudinal direction of the mandrel 23 with respect to the distal end surface of the opening 22b of the nozzle 22 in the state of spraying liquid. 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 first embodiment, if the opening diameter of the opening 22b of the nozzle 22 is 0.2 mm and the electrostatic force is not considered, the liquid coming out of the opening 22b of the nozzle 22 is It comes out in a hemispherical shape with a diameter of about 0.2 mm at the tip.

The tip of the mandrel 23 is preferably located near the liquid so that an electric field (electrostatic force) acts on the liquid coming out of the nozzle 22 to form a conical Taylor cone 60. For this reason, the tip of the mandrel 23 is preferably located within 2 mm forward (in the exit direction) from the tip surface of the opening 22b of the nozzle 22. On the other hand, it is preferable that the tip of the mandrel 23 be located within 2 mm rearward (in the direction of retraction) from the tip surface of the opening 22b of the nozzle 22 so as to affect the adhesion of liquid.

As described above, by providing the mandrel 23, stable atomization of the liquid can be achieved even if the opening diameter of the opening 22b of the nozzle 22 is formed relatively large.
Therefore, the opening diameter of the opening 22b of the nozzle 22 can be made large enough to suppress clogging.
Further, since the opening diameter of the opening 22b of the nozzle 22 can be made relatively large, the nozzle 22 can be manufactured by machining.

In the first embodiment, a case is shown in which the tip of the mandrel 23 is a flat plane as the tip surface 23d, but the present invention is not limited to this, as long as it contributes to the stable formation of the Taylor cone 60. For example, the tip of the mandrel 23 may have a curved surface protruding toward the front side, such as an R shape.

FIG. 5 is a perspective view showing a state in which liquid is sprayed from a liquid spraying section 520 of a conventional electrostatic spraying device in which an element equivalent to the shielding member 100 is not provided, and shows the application pattern Q of the sprayed liquid, the application 3 is a perspective view showing a pattern R. FIG.
FIG. 6 is a side view showing a state in which liquid is sprayed from the liquid spraying section 520 of the conventional electrostatic spraying device shown in FIG.
FIG. 7 is a rear view showing a state in which liquid is sprayed from the liquid spraying section 520 of the conventional electrostatic spraying device shown in FIG.
A coating pattern of a liquid sprayed from a liquid spraying section 520 of a conventional electrostatic spraying device will be described with reference to FIGS. 5, 6, and 7.

FIG. 5 shows a conventional electrostatic spraying device in which a liquid is sprayed from a liquid spraying section 520 to form a coating pattern Q and a coating pattern R on the surface of the object 40 to be coated. The process of forming the coating pattern Q and the coating pattern R will be described below.

As shown in FIG. 6, a Taylor cone 60 of the liquid to be applied is formed at the tip of the nozzle 22. This Taylor cone 60 is pulled by an electrostatic force, and a portion of the liquid forming the Taylor cone 60 separates from the nozzle 22 and becomes atomized. This atomized liquid is attracted to and adheres to the surface of the object 40 to be coated, and a coating pattern Q is formed on the surface of the object 40 to be coated.

On the other hand, a liquid pool L is formed on the outer circumferential surface of the tip of the nozzle 22 due to the liquid transmitted from the tip of the nozzle 22 without being drawn forward due to the electrostatic force. This liquid pool L is pulled forward by an electrostatic force acting on its tip, and is separated and atomized. This atomized liquid is attracted to and adheres to the surface of the object 40 to be coated, and a coating pattern R is formed on the surface of the object 40 to be coated.

The application pattern Q originally has a shape close to a circle because the liquid is ejected from the nozzle 22 almost equally in all directions. However, as shown in FIG. 7, the coating pattern Q has a shape in which the side closer to the coating pattern R is shrunk toward the axis LN of the nozzle 22 due to the repulsive force caused by the coating pattern R having the same potential.

As described above, in the liquid spraying section 520 of the conventional electrostatic spraying device, there was a problem in that unintended application patterns Q and R were formed due to the formation of the liquid pool L.

FIG. 8 is a perspective view showing a coating pattern P of the liquid sprayed from the liquid spraying section 20 of the electrostatic spraying device 10 according to the first embodiment of the present invention, FIG. 9 is a side view, and FIG. , is a rear view.
The application pattern P of the liquid sprayed from the liquid spray section 20 of the electrostatic spray device 10 according to the first embodiment of the present invention will be described with reference to FIGS. 8, 9, and 10.

FIG. 8 shows a state in which liquid is sprayed from the liquid spray section 20 in the electrostatic spraying device 10 shown in FIG. 1 to form a coating pattern P on the surface of the object 40 to be coated. The process of forming this coating pattern P will be described below.

As shown in FIG. 9, a Taylor cone 60 of the liquid to be applied is formed at the tip of the nozzle 22. This Taylor cone 60 is pulled by an electrostatic force, and a portion of the liquid forming the Taylor cone 60 separates from the nozzle 22 and becomes atomized. This atomized liquid is attracted to and adheres to the surface of the object 40 to be coated, and a coating pattern P is formed on the surface of the object 40 to be coated.

The liquid transmitted from the tip of the nozzle 22 without being drawn forward due to electrostatic force is transferred to the outer circumferential surface of the tip of the outer circumferential portion 22d of the nozzle 22 between the inner surface 100b of the shielding member 100 facing the outer circumferential surface of the tip of the nozzle 22 and the nozzle. It accumulates in a gap F in a direction perpendicular to the axis LN of the nozzle 22, which is provided between the tip and the outer circumferential surface of the nozzle 22. The shielding member 100 shields the electrostatic force from acting on the covered portion near the outer peripheral surface of the tip of the nozzle 22 . Therefore, no electrostatic force acts on the liquid accumulated in the gap F, and the liquid accumulated in the gap F is not pulled by the electrostatic force. Therefore, the liquid accumulated in the gap F does not separate from the nozzle 22 and become atomized, and formation of an unintended coating pattern on the surface of the object 40 is prevented.

In this way, by covering at least a part of the outer circumferential surface of the tip of the nozzle 22 with the shielding member 100 and providing the gap F, it is possible to prevent the formation of an unintended application pattern and to achieve the intended application pattern as shown in FIG. Only a nearly circular coating pattern P can be formed.

As shown in FIG. 9, the shielding member 100 may have a distal end portion 100a, which is the distal end of the shielding member 100, located behind the distal end of the nozzle 22.

The distal end 100a of the shielding member 100 is preferably disposed 1 mm or more and 5 mm or less behind the distal end of the nozzle 22, and more preferably 1 mm or more and 3 mm or less rearward. That is, in FIG. 9, the rearward distance E of the tip 100a, which is the tip of the shielding member 100, with respect to the tip of the nozzle 22 is preferably 1 mm or more and 5 mm or less, and more preferably 1 mm or more and 3 mm or less.

When the distance E is 1 mm or more, the electrostatic force is sufficiently applied to the tip of the nozzle 22, so that the liquid can be sprayed appropriately.

Further, by setting the distance E to 5 mm or less, formation of a liquid pool on the outer circumferential portion 22d of the nozzle 22 on the front side of the tip portion 100a of the shielding member 100 is more effectively suppressed. By suppressing the formation of liquid pools, it is possible to more effectively suppress the formation of an unintended coating pattern such as coating pattern R in FIG. 7 on the surface of the object 40 to be coated.

As shown in FIGS. 4 and 9, the shielding member 100 covers the outer peripheral surface of the tip of the nozzle 22. As shown in FIGS. The electrostatic spraying device 10 has a gap F in a direction perpendicular to the axis LN of the nozzle 22 between the inner surface 100b of the shielding member 100 that faces the outer circumferential surface of the tip of the nozzle 22 and the outer circumferential surface of the tip of the nozzle 22. are doing. That is, in FIG. 9, a gap F is provided between the inner surface 100b of the shielding member 100 and the outer peripheral surface of the tip of the outer peripheral portion 22d of the nozzle 22. As shown in FIG.

The gap F between the inner surface 100b of the shielding member 100 and the outer peripheral surface of the tip of the nozzle 22 may be 0.2 mm or more and 5 mm or less in a direction perpendicular to the axis LN of the nozzle 22, and may be 1 mm or more and 5 mm or less. It may be 1 mm or more and 3 mm or less.

By setting the gap F to 0.2 mm or more and 5 mm or less, the liquid transmitted from the tip of the nozzle 22 can more easily accumulate in the gap F without being drawn forward by electrostatic force. Since the shielding member 100 blocks the action of electrostatic force on the portion covered by the shielding member 100, the electrostatic force does not act on the liquid accumulated in this gap F. Therefore, formation of an unintended coating pattern such as coating pattern R in FIG. 7 on the surface of the object to be coated 40 can be more effectively suppressed. Moreover, since the gap F is 5 mm or less, electrostatic force acts on the liquid pool formed in the gap F from the front side, and the liquid is prevented from separating to the front side and becoming atomized. Therefore, formation of an unintended coating pattern on the surface of the object to be coated 40 can be more effectively suppressed.

As shown in FIGS. 4, 9, etc., the shielding member 100 is formed in a cylindrical shape and is shown so as to cover the entire circumference of the outer peripheral surface of the tip of the nozzle 22. As shown in FIGS. However, the shielding member 100 is not limited to covering the entire circumference of the outer peripheral surface of the tip of the nozzle 22. If a liquid puddle is formed in a certain direction, for example, only on the lower side of the nozzle 22, cover only the lower side of the nozzle 22 and block the action of electrostatic force on the covered part of the nozzle 22. You can do it like this. That is, the shielding member 100 may be formed in a cylindrical shape and cover the entire circumference of the outer peripheral surface of the tip of the nozzle 22, or may cover a part of the outer circumferential surface of the tip of the nozzle 22.
<Second embodiment>

FIG. 11 is a cross-sectional view showing a liquid spray section 20 and a shielding member 200 according to a second embodiment of the present invention.
A liquid spraying section 20 and a shielding member 200 according to a second embodiment will be described using FIG. 11.

The electrostatic spraying device according to the second embodiment differs in configuration from the electrostatic spraying device 10 according to the first embodiment in that it includes a cleaning mechanism 230. Below, points different from the electrostatic spraying device 10 according to the first embodiment will be explained, and the same or corresponding parts will be given the same reference numerals, and the description will not be repeated in principle.

The electrostatic spraying device according to the second embodiment includes a cleaning mechanism 230 that cleans the gap F to remove liquid accumulated therein, and the cleaning mechanism 230 is configured to be able to supply cleaning liquid to the gap F. Here, the gap F is the same element as the gap F in the first embodiment.

The cleaning mechanism 230 includes a supply storage unit (not shown) that stores and supplies cleaning liquid, a connection supply unit 231 that supplies the cleaning liquid supplied from the supply storage unit to the gap F, and a connection supply unit 231 that supplies cleaning liquid supplied from the connection supply unit 231. and a receiving part 150 for receiving into the gap F.

The supply storage unit includes a cleaning liquid storage unit that stores cleaning liquid, a cleaning liquid delivery unit that sends out the cleaning liquid stored in the cleaning liquid storage unit, and a liquid delivery unit that sends the cleaning liquid sent out by the cleaning liquid delivery unit to the connection supply unit 231. , is provided. The cleaning liquid delivery unit includes a liquid pump for sending the cleaning liquid. Further, the liquid feeding section is formed in a tubular shape, and is formed of, for example, a pipe or a hose.

The connection supply section 231 includes an inlet 231a that is an upstream opening through which cleaning liquid is supplied, an outlet 231b that is a downstream opening, and a supply path 231c that connects the inlet 231a and the outlet 231b. Be prepared. The connection supply section 231 is formed in a tubular shape, and is formed of, for example, a pipe or a hose. The connection supply unit 231 is connected on the upstream side to a supply storage unit that supplies cleaning liquid. That is, the inlet port 231a is directly or indirectly connected to the liquid feeding section of the supply storage section.

The receiving part 150 is provided in the shielding member 200, as shown in FIG. The shielding member 200 of the second embodiment shown in FIG. The structure is different from that of the shielding member 100 of the present invention. The shielding member 200 is the same as the shielding member 100 of the first embodiment in other respects.

That is, like the shielding member 100, the shielding member 200 covers at least a portion of the outer peripheral surface of the tip of the nozzle 22. Thereby, the shielding member 200 shields the covered portion from the action of electrostatic force. Further, an inner surface 200b, which is an inner surface of the shielding member 200, is arranged to face the outer circumferential surface of the tip of the nozzle 22. A gap F in a direction perpendicular to the axis LN of the nozzle 22 is provided between the inner surface 200b of the shielding member 200 and the outer peripheral surface of the tip of the nozzle 22. The shielding member 200 also includes openings at both ends in the direction of the axis LN (specifically, the front end 200a, which is the front end, and the rear end 200c, which is the rear end).

The outlet 231b of the connection supply section 231 and the receiving section 150 are connected to communicate with each other. The connection part 240, which is the part where the outlet 231b and the receiving part 150 are connected in communication, is connected in a sealed state so that the cleaning liquid supplied from the outlet 231b to the receiving part 150 does not leak to the outside. . For example, as shown in FIG. 11, the receiving portion 150 is formed of a through hole provided by connecting an outer surface 200e, which is the outer surface, of the shielding member 200, and an inner surface 200b, which is the inner surface. On the other hand, the connection supply section 231 is formed in a tubular shape. The connecting portion 240 is formed by welding or the like over the entire circumference with the tubular end of the connecting supply portion 231 abutting the outer peripheral portion outside the opening of the through hole forming the receiving portion 150. . However, the connecting portion 240 is not limited to the configuration and structure shown in FIG. 11. For example, the connection section 240 may be configured by joining the tubular end of the connection supply section 231 and the receiving section 150 with a tubular joint member (not shown).

FIG. 12 is a sectional view showing a modification of the liquid spray section 20 and the shielding member 200 according to the second embodiment of the present invention shown in FIG.
A modification of the liquid spray section 20 and the shielding member 200 according to the second embodiment shown in FIG. 11 will be described using FIG. 12.

In the cleaning mechanism 230 shown in FIG. 11, the receiving part 150 is provided in the shielding member 200. In contrast, the cleaning mechanism 230 shown in FIG. 12 differs in that the receiving section 150 is provided in the body section 21A of the liquid spraying section 20. Therefore, the shielding member 200A in which the receiving portion 150 is not provided is the same as the shielding member 100 of the first embodiment.

As shown in FIG. 12, the receiving section 150 includes a receiving port 150a, a supply port 150b, and a receiving supply path 150c. The receiving port 150a is an opening provided in the outer circumference of the body 21f, which is the outer circumference of the body 21A. The supply port 150b is an opening provided in the body distal end portion 21h, which is the distal end portion of the body portion 21A. The reception supply path 150c is a flow path that is provided inside the body portion 21A and connects the reception port 150a and the supply port 150b. In front of the supply port 150b, a gap F is provided in a direction perpendicular to the axis LN of the nozzle 22 between the inner surface 200b of the shielding member 200A and the outer peripheral surface of the tip of the nozzle 22.

The cleaning liquid supplied to the reception port 150a flows through the reception and supply path 150c and is sent out from the supply port 150b. The cleaning liquid sent out from the supply port 150b is then supplied to the gap F. That is, in the cleaning mechanism 230 shown in FIG. 12, the receiving section 150 supplies the cleaning liquid received at the receiving port 150a to the gap F from the supply port 150b via the receiving supply path 150c.

The outlet 231b of the connection supply section 231 and the receiving section 150 are connected in communication, as in the case shown in FIG. 11. As shown in FIG. 12, the outlet 231b of the connecting supply section 231 is connected to the receiving port 150a of the receiving section 150. The connecting part 240, which is the part where the outlet 231b and the receiving part 150 are connected in communication, is sealed tightly so that the cleaning liquid supplied from the outlet 231b to the receiving part 150a of the receiving part 150 does not leak to the outside. It is connected in the state that it is connected.

Next, the flow of the supplied cleaning liquid will be explained. In FIGS. 11 and 12, the cleaning liquid is supplied from the supply storage section to the connection supply section 231. The cleaning liquid supplied to the inlet 231a of the connection supply section 231 flows to the outlet 231b through the supply path 231c. The cleaning liquid supplied from the outlet 231b flows into the receiving part 150. The cleaning liquid flowing through the receiving portion 150 is supplied to the gap F inside the shielding members 200 and 200A.

Inside the shielding members 200, 200A, the cleaning liquid that has passed through the gap F between the inner surface 200b of the shielding members 200, 200A and the outer peripheral surface of the tip of the nozzle 22 flows through the opening of the tip 200a of the shielding members 200, 200A. It is discharged to the outside.

In this way, the cleaning liquid received from the receiving part 150 passes through the gap F, thereby cleaning the gap F so as to remove the liquid accumulated therein. The cleaning liquid that has cleaned the gap F is discharged to the outside from the opening of the tip 200a on the front side of the shielding members 200, 200A.

In addition, as shown in FIG. 11, when the receiving part 150 is provided in the shielding member 200, the receiving part 150 is provided in the shielding member 200 in order to make the flow of the cleaning liquid from the rear side to the front side of the shielding member 200. It is desirable to provide it on the rear side of the center of the member 200. By doing so, the liquid accumulated in the gap F can be removed more reliably.

The cleaning mechanism 230 may be configured to be able to supply compressed gas to the gap F in addition to the cleaning liquid. The connection supply section 231 of the cleaning mechanism 230 may supply compressed gas in addition to the cleaning liquid. In addition, the supply storage unit connects the compressed gas storage unit that stores compressed gas, the compressed gas delivery unit that sends out the compressed gas stored in the compressed gas storage unit, and the compressed gas sent out by the compressed gas delivery unit. It may further include a gas feeding section that sends gas to the supply section 231. The compressed gas delivery unit includes a gas pump for sending compressed gas. The gas feeding section is formed in a tubular shape, and is formed of, for example, a pipe or a hose.

When the cleaning mechanism 230 can supply compressed gas to the gap F, the flow of the supplied compressed gas is similar to the flow of the supplied cleaning liquid. That is, compressed gas is supplied to the connection supply section 231 from the supply storage section. The compressed gas supplied to the inlet 231a of the connection supply section 231 flows to the outlet 231b through the supply path 231c. The compressed gas supplied from the outlet 231b flows into the receiving part 150. The compressed gas that has flowed through the receiving portion 150 is supplied to the gap F inside the shielding members 200 and 200A.

Inside the shielding members 200, 200A, the compressed gas that has passed through the gap F between the inner surface 200b of the shielding members 200, 200A and the outer peripheral surface of the tip of the nozzle 22 is discharged to the outside from the opening of the tip 200a. .

Next, a cleaning method for cleaning the gap F using the cleaning mechanism 230 will be described. This cleaning method includes a step of supplying a cleaning liquid to the gap F to clean it (cleaning step). Moreover, this cleaning method may further include a step of drying the gap F by supplying gas to the gap F (drying step).

In the cleaning process, first, a cleaning liquid is supplied inside the shielding members 200 and 200A (cleaning liquid supply process). Next, the supplied cleaning liquid is passed through the gap F to perform cleaning to remove the liquid accumulated in the gap F (a gap cleaning step). The cleaning liquid and the removed liquid are then discharged to the outside from the openings of the tips 200a of the shielding members 200, 200A (cleaning liquid discharge step). In this way, the cleaning process includes a cleaning liquid supply process, a gap cleaning process, and a cleaning liquid discharge process. By performing this cleaning step, liquid and the like in the gap F are removed.

In the drying process, compressed gas is first supplied into the shielding members 200 and 200A (compressed gas supply process). Next, the supplied compressed gas is passed through the gap F to dry the inner surfaces 200b of the shielding members 200 and 200A forming the gap F, the outer peripheral surface of the tip of the nozzle 22, etc. (gap drying step). Then, the compressed gas is discharged to the outside from the opening of the tip portion 200a of the shielding members 200, 200A (compressed gas discharge step). In this compressed gas discharging step, in addition to discharging the compressed gas, liquid and cleaning liquid remaining in the gap F may also be discharged together due to the action of the flow of the compressed gas. Thus, the drying process includes a compressed gas supply process, a gap drying process, and a compressed gas discharge process. By performing this drying process, the cleaning liquid and the like in the gap F are removed.

The cleaning liquid is appropriately selected depending on the type of liquid. When the liquid is paint, an organic solvent such as thinner is selected as the cleaning liquid. Moreover, compressed air is mainly used as the compressed gas. However, the compressed gas may be a gas other than compressed air, such as a nonflammable gas.

In an electrostatic spray device, a liquid may be continuously sprayed. In this case, the liquid transmitted from the tip of the nozzle 22 also accumulates near the tip portion 200a of the shielding member 200, 200A inside the shielding member 200, 200A. If the liquid is further sprayed in this state, the liquid will not be contained inside the shielding members 200, 200A and will overflow to the outside of the shielding members 200, 200A. Electrostatic force acts on the liquid overflowing to the outside of the shielding members 200, 200A and atomizes the liquid, forming an unintended coating pattern such as the coating pattern R shown in FIGS. 5 to 7.

The electrostatic spraying device according to the second embodiment includes a cleaning mechanism 230 that cleans the gap F to remove liquid accumulated therein, and the cleaning mechanism 230 is configured to be able to supply cleaning liquid to the gap F. The cleaning mechanism 230 is then used to perform each step of the cleaning method described above. As a result, the liquid accumulated in the gap F is removed. In addition, it is possible to prevent the liquid from overflowing to the outside of the shielding members 200, 200A. This can prevent formation of unintended coating patterns such as coating patterns R shown in FIGS. 5 to 7.

Although the present invention has been described above based on specific embodiments, the present invention is not limited to the above embodiments, and modifications and improvements may be made as appropriate.

For example, although the case where the electrostatic spray device is a single nozzle having only one nozzle has been described above, the case is not limited to this, and the same applies to a multi-nozzle electrostatic spray device having multiple nozzles. be.

In the second embodiment, the receiving portion 150 shown in FIG. 11 is not limited to being provided by connecting the outer surface 200e and the inner surface 200b of the shielding member 200. For example, the receiving portion 150 may be provided at the rear end portion 200c of the shielding member 200 to supply the cleaning liquid to the gap F. Further, the receiving portion 150 may be provided integrally with the opening of the rear end portion 200c. Thereby, the entire area or almost the entire area inside the shielding member 200, from the rear end 200c to the tip 200a, can be reliably cleaned.

In the second embodiment, the receiving section 150 shown in FIG. 12 is not limited to having only one supply port 150b. The receiving portion 150 may include a plurality of supply ports 150b in the circumferential direction of the body tip portion 21h. For this reason, the reception supply path 150c may be branched in the middle and connected to a plurality of supply ports 150b. Thereby, the cleaning liquid is evenly supplied to the entire area of the gap F. In addition, the liquid accumulated in the gap F can be removed more reliably.

In the second embodiment, the opening on the rear end 200c side of the shielding member 200A shown in FIG. 12 is formed in a tapered shape so that the rear inner peripheral part 200d, which is the inner peripheral part thereof, widens toward the rear. Further, the tip outer peripheral portion 21g of the body portion 21A has a tapered shape that tapers toward the front. The shielding member 200A is attached to the liquid spraying part 20 by fitting the rear inner peripheral part 200d of the shielding member 200A to the outer peripheral part 21g of the distal end of the body part 21A from the outside. The tapered rear inner circumferential portion 200d may be provided such that its front end portion is at the same position in the front-rear direction as the body tip portion 21h, or is located in front of the same position. As a result, all or almost all of the space where liquid may accumulate inside the shielding member 200A is formed in front of the supply port 150b through which the cleaning liquid is supplied. Thereby, the liquid accumulated in the gap F can be removed more reliably. For this purpose, as shown in FIG. 12, the outer diameter of the rear outer surface 200f, which is the outer circumferential surface on the rear side, may be made larger than the outer diameter of the outer circumferential surface 200e, which is the other outer circumferential surface.

As described above, the present invention is not limited to specific embodiments, and suitable modifications and improvements are also included within the technical scope of the present invention, which is understood by those skilled in the art. It is clear from the description of the claims.

10 Electrostatic spray device 20 Liquid spray parts 21, 21A Body part 21a Liquid supply port 21b Liquid flow path 21c Hole 21d Rear end opening 21e Female screw structure 21f Body outer circumference 21g Tip outer circumference 21h Body tip 22 Nozzle 22a Tip Outer periphery 22b Opening 22d Outer periphery 23 Mandrel 23a Knob 23b Electrical wiring connection 23c Male screw structure 23d Tip surface 24 Seal member 40 Different poles (object to be coated)
50 Voltage application means 60 Taylor cone 80 Earthing means 100 Shielding member 100a Tip part 100b Inner surface 100c Rear end part 100d Rear inner peripheral part 150 Receiving part 150a Receiving port 150b Supply port 150c Receiving supply path 200, 200A Shielding member 200a Tip part 200b Inside Side surface 200c Rear end portion 200d Rear inner peripheral portion 200e Outer surface 200f Rear outer surface 230 Cleaning mechanism 231 Connection supply section 231a Inlet port 231b Outlet port 231c Supply path 240 Connection section 520 Liquid spray section

Claims (6)

An electrostatic device that sprays the liquid from the nozzle toward the different polarity part by applying a voltage between a liquid spraying part including a nozzle that sprays the liquid and a different polarity part having a different polarity with respect to the liquid spraying part. An electrostatic spraying device using a spray method,
the liquid spray section;
Voltage application means that applies a voltage between the liquid spraying part and the different polarity part to generate an electrostatic force that causes the liquid to separate from the nozzle in a charged state and atomize it;
a shielding member that covers at least a portion of the outer peripheral surface of the tip of the nozzle and shields the electrostatic force from acting on the covered portion;
An electrostatic spraying device, wherein a gap is provided in a direction perpendicular to the axis of the nozzle between an inner surface of the shielding member that faces the outer circumferential surface of the tip of the nozzle and an outer circumferential surface of the tip of the nozzle. The shielding member has a tip disposed behind the tip of the nozzle,
The electrostatic spray device according to claim 1. The shielding member has a tip disposed at least 1 mm and no more than 5 mm behind the tip of the nozzle,
The electrostatic spray device according to claim 2. The gap between the inner surface of the shielding member and the outer peripheral surface of the tip of the nozzle is 0.2 mm or more and 5 mm or less in a direction perpendicular to the axis of the nozzle.
The electrostatic spray device according to claim 1. The shielding member covers the entire circumference of the outer peripheral surface of the tip of the nozzle,
The electrostatic spraying device according to claim 1 or claim 2. comprising a cleaning mechanism for cleaning to remove the liquid accumulated in the gap,
The cleaning mechanism is configured to be able to supply cleaning liquid to the gap.
The electrostatic spray device according to claim 1.

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