JP2017170412A - Electrostatic atomizer and electrostatic atomization method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electrostatic atomizer and an electrostatic atomization method which enable a coating workpiece to be coated with a liquid such as a paint regardless of the size of the coating workpiece.SOLUTION: An electrostatic atomizer 10 comprises: liquid spray part 20 having a nozzle 22; a holder 30, which is a holder for holding a coating workpiece 40 partially or entirely conductive or semi-conductive, turning heteropolar to the liquid spray part 20, and makes the held coating workpiece 40 heteropolar to the liquid spray part 20; and voltage impressing means 50 for generating electrostatic force that separates a liquid from the nozzle 22 in a static electrification state to coat the coating workpiece 40 with the liquid by impressing voltage between the liquid spray part 20 and the holder 30, where the holder 30 has a coating workpiece holder 31 for holding a part except the planned part of liquid coating that coats the coating workpiece 40 with the liquid.SELECTED DRAWING: Figure 2

Description

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

  2. Description of the Related Art Conventionally, an apparatus is known that can apply a voltage between a nozzle body and a target plate to charge and spray a liquid from the nozzle toward the target plate (see Patent Document 1).

JP 2008-516766 A

In the apparatus described in Patent Document 1, if the target plate is an object to be coated with paint or the like and the liquid to be sprayed is paint or the like, it is used for the purpose of applying liquid such as paint to the object to be coated. Is possible.
However, there are various sizes of objects to be coated with paints and the like, and in the case of a minute-sized object, an electrode for applying a voltage between the object and the nozzle body is used. There is a problem that it is difficult to connect electric lines.

  Furthermore, in order to apply a voltage between the object to be coated and the nozzle body to atomize the liquid, it is necessary that the object to be coated itself serve as an electrode having a different polarity from the nozzle body. The small size of the object is equivalent to the small size of the electrode, so in the case of a small-sized object, the function as a different polarity to the nozzle body cannot be achieved, and it is difficult to atomize the liquid itself There is also the problem of being.

  The present invention has been made in view of such circumstances, and an electrostatic spraying apparatus and an electrostatic spraying method capable of applying a liquid such as a paint to a coating object regardless of the size of the coating object. The purpose is to provide.

The present invention is grasped by the following composition in order to achieve the above-mentioned object.
(1) The electrostatic spraying device of the present invention is a liquid spraying unit having a nozzle, and a holding body for holding an object to be partially or wholly made conductive or semiconductive, with respect to the liquid spraying unit. Applying a voltage between the holding body that has a different polarity and also holds the object to be coated with a different polarity with respect to the liquid spraying part, and between the liquid spraying part and the holding body, the liquid is applied to the object to be coated. Voltage applying means for generating an electrostatic force that separates the liquid from the nozzle in a charged state so that the liquid is applied, and the holding body is a liquid application scheduled part for applying the liquid of the object to be coated It has a to-be-coated part holding part which hold | maintains.

(2) In the configuration of (1), the holding body is made of a material that can absorb the liquid.

(3) In the configuration of (1) or (2), the coating object holding portion is a through hole having an inner shape substantially the same as the outer shape of the pipe-shaped coating object, and the outer surface of the coating object is Hold.

(4) In the configuration of (3), the through hole has a circular shape corresponding to a circular outer diameter of the article to be coated, and the diameter of the through hole has an outer diameter of 30 mm or less. It is set to 30 mm or less depending on the object.

(5) In any one configuration of the above (1) to (4), the holding body includes a plurality of the object holding portions.

(6) In the configuration of the above (1) or (2), the object holding portion has an outer shape substantially the same as an inner shape of the pipe-shaped object to be coated, and an inner surface of the pipe-shaped object to be coated. Hold.

(7) In the configuration of (6), an outer shape of the object holding portion is a circular shape corresponding to a circular through hole provided in the object to be coated having a maximum outer shape of 30 mm or less, The diameter of the coating material holding part is set to less than 30 mm in accordance with the inner diameter of the through hole of the coating object.

(8) In the configuration of (6) or (7), the object holding unit has a length capable of holding a plurality of the objects to be coated.

(9) In the electrostatic spraying method of the present invention, a part or all of the liquid spraying part is made conductive or semiconductive. Applying a voltage between the liquid spraying unit and the holding body, and a coating object holding step for holding a part other than the liquid coating scheduled part for applying the liquid of the coating object so as to have a different polarity with respect to the spraying part And an application step of applying the liquid to the object to be coated by separating the liquid from a nozzle of the liquid spraying portion in an charged state by electrostatic force.

(10) In the configuration of (9), the coating object holding step is configured to remove the circular pipe-shaped coating object having an outer diameter of 30 mm or less from a through hole having an inner diameter substantially equal to the outer diameter of the coating object. A step of fitting the object into the through-hole so that the outer surface of the object is held by the object holding part, and the applying step is an inner surface of the circular pipe-shaped object The step of applying the liquid to the liquid.

(11) In the configuration of (10), the object holding step is a step of fitting a plurality of objects to be coated into a plurality of object holding parts including through holes provided in the holding body. The applying step is a step of applying the liquid to each of the inner surfaces of the plurality of objects to be coated.

(12) In the configuration of (9), the object holding step has a circular shape corresponding to a circular through hole provided in the object to be coated having a maximum outer shape of 30 mm or less, and the object to be coated A step of mounting the article to be coated on the article holding part so that the article holding part having an outer diameter substantially equal to the inner diameter of the through hole of the article holds the inner surface of the through hole of the article to be coated. And the applying step is a step of applying the liquid to the outer surface of the article to be coated.

(13) In the configuration of (12), the object holding step is a step of mounting the object to be coated so as to stack a plurality of objects to be coated, and the step of applying includes a plurality of steps. Applying the liquid to each outer surface of the article to be coated;

  ADVANTAGE OF THE INVENTION According to this invention, the electrostatic spraying apparatus and electrostatic spraying method which can be made to apply liquids, such as a coating material, to a to-be-coated object irrespective of the magnitude | size of a to-be-coated object can be provided.

It is the top view which looked at the electrostatic spraying apparatus of 1st Embodiment which concerns on this invention from the upper side. It is the sectional view on the AA line of FIG. It is an expanded sectional view of the front end side of the liquid spraying part of FIG. It is a perspective view for demonstrating the holding body of 1st Embodiment which concerns on this invention. It is a perspective view for demonstrating the holding body of 2nd Embodiment which concerns on this invention.

DESCRIPTION OF EMBODIMENTS 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 plan view of an electrostatic spraying device 10 according to a first embodiment of the present invention as viewed from above, and FIG. 2 is a cross-sectional view taken along line AA in FIG.
In FIG. 2, a state in which a liquid such as a paint is sprayed from the liquid spraying unit 20 as illustrated later is also illustrated.

As shown in FIGS. 1 and 2, the electrostatic spraying device 10 is disposed separately from the liquid spraying unit 20 having the nozzle 22 and the nozzle 22, and a part or all of the electrostatic spraying device 10 is made conductive or semiconductive. A holding body 30 that holds the object to be coated 40 and has a different polarity with respect to the liquid spraying unit 20 and also has a holding object 40 that has a different polarity with respect to the liquid spraying part 20, and the liquid spraying unit 20 and the holding body Voltage application means 50 (voltage power supply) for applying a voltage between 30 and 30.
The semiconducting property means that, for example, the surface resistance is 10 ¹⁰ Ω or less and it is in an antistatic state.

The electrical wiring connected from the voltage application means 50 to the holding body 30 is connected to the grounding means 60 so that the holding body 30 is grounded.
The grounding means 60 is not an essential requirement.
However, since the holding body 30 is a member that is touched by an operator during an operation for holding the article to be coated 40, the grounding means 60 is provided to ground the holding body 30 from the viewpoint of safety. It is preferable to do.

(Liquid spray part)
As shown in FIG. 2, the liquid spray unit 20 includes a body part 21 made of an insulating material in which a liquid channel 21 b having a liquid supply port 21 a to which a liquid is supplied is formed, and a through-hole serving as a liquid flow of the body part 21. A nozzle 22 provided at the tip of the body portion 21 so as to communicate with the passage 21b, and a mandrel 23 made of a conductive material disposed in the liquid flow path 21b of the body portion 21 and in the through hole of the nozzle 22. Yes.

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, and a gap between the mandrel 23 is sealed in the hole portion 21c. A seal member 24 is provided to prevent liquid from leaking.
In this embodiment, an O-ring is used as the seal member 24. However, the O-ring is not limited to the O-ring, and any member that can be sealed may be used.

  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 made of an insulating material is provided and provided so as to penetrate almost the center of the knob portion 23a. An electrical wiring connection portion 23b made of the conductive material thus provided is provided.

  As shown in FIG. 2, the electrical wiring connecting portion 23 b is connected to the electrical wiring from the voltage applying means 50, and the electrical wiring connecting portion 23 b is in contact with the mandrel 23 so that the mandrel 23 and the electrical wiring are connected. The part 23b is electrically connected.

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

  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, while a male screw is provided on the outer peripheral surface of the tip portion of the knob portion 23a. A structure 23c is provided.

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

Here, in general, the nozzle for spraying the liquid of the electrostatic spraying device is a fine liquid passage having a small diameter of the through hole through which the liquid flows.
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. However, since the opening diameter is small, there is a problem that it is difficult to eliminate this clogging.

However, the reason will be explained later. However, by using the mandrel 23, it has been found that the atomization can be favorably atomized even when the opening diameter at the tip of the nozzle is larger than that in the prior art. The opening diameter of the opening 22b at the tip of the nozzle 22 of the present embodiment is a large opening diameter of 0.2 mm.
As a result, the frequency of occurrence of clogging can be greatly reduced.

  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 preferably 0.1 mm or more, more preferably 0.2 mm or more, considering that clogging is unlikely to occur and cleaning is possible even when clogging occurs, and more preferably 0.2 mm or more. It is preferable to make it larger than 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 consideration of the stability of 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, the mandrel 23 can be removed and a large amount of washing liquid can be flowed for washing.

  FIG. 3 is an enlarged view in which the distal end side of the liquid spraying part 20 is enlarged. FIG. 3A is a case where the distal end surface 23d of the mandrel 23 is located rearward, and FIG. This is a case where the distal end surface 23d of the mandrel 23 is located in front of the state of (a).

  As shown in FIG. 3A, the nozzle 22 has a tapered inner diameter portion (refer to the range W1) having a taper angle α that becomes smaller in taper toward the opening portion 22b. Has a tapered portion (see range W2) having a taper angle β of which the outer diameter becomes smaller toward the distal end surface 23d.

The taper angle α of the tapered inner diameter portion of the nozzle 22 is set 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 end side of the nozzle 22 and the mandrel 23, as can be seen by comparing FIG. 3A and FIG. The width of the gap formed by the mandrel 23 can be adjusted, and 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. 3B, the mandrel 23 can abut against the inner peripheral surface of the nozzle 22 to close the opening 22 b of the nozzle 22. It is.
Therefore, it is possible to prevent the liquid in the nozzle 22 from being dried by blocking the opening 22b of the nozzle 22 with the mandrel 23 in a state where the liquid such as paint is not sprayed, and to suppress the clogging of the nozzle 22. it can.

(Holding body)
FIG. 4 is a perspective view for explaining the holding body 30.
As shown in FIG. 4, the holding body 30 has a plurality of object holding parts 31 that hold the object 40 to be held, and the object 40 is held in the object holding part 31.

In the present embodiment, the object to be coated 40 has a circular outer diameter and has a pipe shape with a hole in the inside, and a liquid application scheduled portion on which an inner surface 41 of the object to be coated 40 applies a liquid. It is.
In addition, in this embodiment, although the case where the to-be-coated article 40 is circular pipe shape is shown, pipe shapes other than circular shapes, such as a square pipe, may be sufficient.

  And the to-be-coated object holding | maintenance part 31 provided in the holding body 30 is comprised by the through-hole of the internal shape (inside diameter in the case of a circle) substantially the same as the external shape (outer diameter in the case of a circle) of the pipe-shaped to-be-coated object 40. The outer surface 42, which is a portion other than the liquid application scheduled portion (inner surface 41) to which the liquid of the object 40 is applied, is held.

  As described above, when the coating object holding unit 31 holds the entire surface of the outer surface 42 that is not a part to which the liquid of the coating object 40 is applied, an effect of masking a part where the liquid is not applied can be obtained. .

On the other hand, although the coating object holding part 31 covers the entire circumference of the outer surface 42 of the coating object 40, depending on the viscosity of the liquid, there is a gap between the coating object holding part 31 and the outer surface 42 of the coating object 40. In some cases, the liquid may enter the outer surface 42 of the article 40 and the liquid may be applied.
In view of this, when the liquid is applied to the article 40 due to such penetration, the holder 30 may be formed of a material that can absorb the liquid to be applied.

For example, the holding body 30 may be formed of a material that easily absorbs liquid, such as cardboard or nonwoven fabric.
In the case of such a material, it is possible to show a resistance value similar to that of the antistatic material having a surface resistance of 10 ¹⁰ Ω or less by including moisture. It is possible to accomplish.
Note that a material having conductivity such as carbon may be contained so as to have a lower resistance value.

  In this way, when a material capable of absorbing liquid is used for the holding body 30, the liquid applied so as to come into contact with the holding body 30 is absorbed by the holding body 30. Even if the liquid does not enter between the outer surfaces 42 of the object to be coated 40 or does not enter, the entering liquid is eventually absorbed by the holding body 30 so that no liquid remains on the outer surface 42 of the object to be coated 40. it can.

  Next, with reference to FIG. 2, first, a state in which the liquid is sprayed from the liquid spraying unit 20 will be described, and then an electrostatic spraying method using the electrostatic spraying device 10 will be described.

  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 by the electrostatic force accompanying the voltage applied between the holding body 30 and the mandrel 23 having a different polarity, Pulled forward and disengaged and atomized forward.

  In addition, the supply of the liquid should just be sequentially supplied with the liquid which is lost from the liquid spraying part 20 by being consumed by spraying, and the opening 22b of the nozzle 22 (more precisely, the opening 22b and the mandrel) 23, it is not necessary to be pumped and supplied at such a pressure that the liquid is ejected from the gap 23). In the state where the liquid is ejected vigorously, it may be impossible to atomize.

  More specifically, the electrostatic force that pulls the liquid forward is balanced against the adhesive force due to the surface tension and viscosity of the tip 23d of the liquid mandrel 23 and the outer peripheral edge 22a of the nozzle 22 as shown in FIG. As shown, a tailor cone 80 in which the liquid supplied to the tip side of the nozzle 22 has a conical shape at the tip is formed.

The tailor cone 80 is formed into a conical shape by separating positive / negative charges in the liquid by the action of an electric field and deforming the meniscus at the tip of the nozzle 22 charged with excess charge.
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 been separated from the nozzle 22 into liquid particles, has a drastically larger area in contact with air than the state before separation, and thus the evaporation of the solvent is promoted. The distance between the charged electrons is reduced as the gas is evaporated, electrostatic repulsion (electrostatic explosion) occurs, and the liquid particles are further divided into small liquid particles.

When this splitting occurs, the surface area in contact with air increases compared to before splitting, so that the evaporation of the solvent is promoted, an electrostatic explosion occurs as described above, and a liquid with a small particle size. Split into particles.
The liquid is atomized by repeating such electrostatic explosion.

Here, in the present 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 outer peripheral edge 22a of the tip of the nozzle 22.

  When the opening diameter of the opening 22b of the nozzle 22 is increased in such a state, the liquid can be attached only to the outer peripheral edge 22a of the tip of the nozzle 22. This makes it impossible to form a clean tailor cone 80 or to maintain the tailor cone 80 itself, so that the stability of the liquid particles detaching from the nozzle 22 (stability of particle size, number, charged state, etc.) is obtained. As a result, it is surmised that stable atomization of the liquid cannot be achieved.

On the other hand, in this embodiment, the mandrel 23 is disposed in the nozzle 22, and the liquid adheres not only to the outer peripheral edge 22 a of the nozzle 22 but also to the distal end 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.

  If the distal end surface 23d of the mandrel 23 protrudes too far forward from the outer peripheral edge 22a of the nozzle 22 (that is, the distal end surface of the opening 22b of the nozzle 22), the electric field is unlikely to act on the liquid exiting the nozzle 22. If the front end surface 23d of the nozzle 23 is retracted too far backward from the front end surface of the opening 22b of the nozzle 22, the state is the same as when there is no portion where the liquid can adhere to the central portion of the opening 22b.

  From this, the position of the tip surface 23d of the mandrel 23 is in the front-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, and when the electrostatic force is not taken into consideration, the liquid discharged from the opening 22b of the nozzle 22 has a diameter of about It comes out to be a hemisphere of 0.2 mm.

  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. Therefore, it is preferable to be located within 2 mm forward (outward direction) from the front end surface of the opening 22b of the nozzle 22, while acting on the adhesion of the liquid. In addition, it is preferable that the tip of the mandrel 23 be positioned within 2 mm behind (in the retracting direction) from the tip surface of the opening 22 b of the nozzle 22.

As described above, by providing the mandrel 23, stable atomization of the liquid can be performed even if the opening diameter of the opening 22b of the nozzle 22 is increased.
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 tip of the mandrel 23 is shown as a flat flat surface as the tip surface 23d. However, the tip of the mandrel 23 is not necessarily a flat flat surface, and the stable tailor cone 80 is formed. Therefore, for example, the tip of the mandrel 23 may be a curved surface protruding toward the front side like an R shape.

The liquid sprayed from the liquid spraying part 20 (nozzle 22) in this way is atomized while repeating electrostatic explosion, and since the atomized liquid is charged, the holding body 30 side having a different polarity is used. Is attracted by the electrostatic force.
Here, the object to be coated 40 is held so as to be in contact with the object to be coated holding portion 31 of the holding body 30, and therefore the object to be coated 40 and the holding body 30 are in a short-circuited state, so The potential state is substantially the same as that of the holding body 30.

  For this reason, since the object to be coated 40 itself has a different polarity as the holder 30, the liquid attracted to the holder 30 side is applied to both the holder 30 and the object to be coated 40. To wear.

  Below, detailed explanation about the coating state etc. of a liquid is given, performing the description about the electrostatic spraying method which applies the liquid to the to-be-coated article 40 using the electrostatic spraying apparatus 10 mentioned above.

  First, the coating object 40 is also different from the liquid spraying part 20 in the coating object holding part 31 of the holding body 30 that is partly or entirely conductive or semi-conductive with respect to the liquid spraying part 20. In this way, an object holding step for holding the part other than the liquid application scheduled part (inner surface 41) where the liquid of the object 40 is applied is performed.

  In the present embodiment, the object holding portion 31 is formed of a through hole having an inner diameter that is substantially the same as the outer diameter of the circular pipe-shaped object 40, so that the object to be coated 40 is fitted into the through hole. The outer surface 42 of the workpiece 40 is held by the workpiece holding portion 31 made of

  Next, the liquid spraying unit 20 is charged with electrostatic force by applying a voltage between the holding body 30 and the liquid spraying unit 20 (more specifically, the mandrel 23) by the voltage applying unit 50. An application step is performed in which the liquid is applied to the object 40 by being separated from the nozzle 22.

  More specifically, the state when the liquid is applied will be described. The liquid detached from the nozzle 22 is atomized while repeating the electrostatic explosion as described above, but at this time, the speed toward the holding body 30 side. Will also accelerate.

  For this reason, the liquid fine particles that have come so as to be located near the center of the through hole of the article to be coated 40 seem to be due to the flying speed, but surprisingly adhere to the edge of the end of the article to be coated 40. Without doing so, it penetrates into the through-hole of the article to be coated 40 and is attracted and applied to the inner surface 41 of the article to be coated.

  In general, there is a spraying device that atomizes a liquid by compressed air and applies a voltage so as to charge the atomized liquid. In such a spraying device, the diameter of the through-hole of the object to be coated is relatively large. Even if it has, the liquid is attracted and applied to the peripheral edge of the end of the object by the edge effect, and it is difficult to apply the liquid to the inner surface of the through hole of the object.

However, in the case of the present embodiment in which spraying is performed only by electrostatic force, the edge effect is hardly seen, and the liquid can be suitably applied to the inner surface 41 of the object to be coated 40.
In addition, even if the diameter of the through hole of the article to be coated 40 is about several millimeters, it was possible to satisfactorily apply the liquid to the inner surface 41.

As described above, according to the configuration of the first embodiment, first, the liquid is satisfactorily applied to the inner surface 41 of the pipe-shaped object 40, which has been difficult in the past, regardless of the size of the object 40. It is possible.
Further, when the size of the object to be coated 40 itself is reduced, it becomes difficult to make the object to be coated 40 itself have a different polarity, and it becomes difficult to spray the liquid itself. Since the holder 30, which is irrelevant to the size, has a different polarity with respect to the liquid spraying unit 20, the liquid can be sprayed without any problem even if the object 40 is a minute size.

  For this reason, the configuration of the present embodiment cannot ensure a size sufficient to serve as an electrode, as in the pipe-shaped object 40 having a small outer shape, and the size of the through hole is small. This is particularly effective when a liquid is applied to the inner surface 41 of the object to be coated 40.

  For example, the object 40 to be coated, such as a square pipe or a circular pipe, having a maximum outer shape of 30 mm or less, for example, a maximum outer shape of 20 mm (or an outer diameter of 20 mm if circular) or a maximum outer shape of 10 mm (if circular) Particularly suitable for those having an outer diameter of less than 10 mm.

Furthermore, if it is set as the aspect hold | maintained so that the to-be-coated-object holding | maintenance part 31 may cover other than the liquid application plan part (inner surface 41) to which the liquid of the to-be-coated object 40 is applied, the part which does not need to apply the liquid The masking effect can be obtained.
In addition, as described above, if the holding body 30 is formed of a material that absorbs liquid, it is possible to suppress extra liquid from being applied to the article 40.

(Second Embodiment)
Next, a second embodiment according to the present invention will be described with reference to FIG.
In the first embodiment, the case where the liquid is applied to the inner surface 41 of the circular pipe-shaped object 40 has been described, but the present invention is not limited to the application of applying the liquid to the inner surface 41. In the second embodiment, a case where a liquid is applied to the outer surface 42 of the article 40 will be described.

For this reason, in the second embodiment, the shape of the holding body 30 is different from that of the first embodiment in accordance with the liquid application scheduled portion on which the outer surface 42 is applied with the liquid. The configuration is the same as in the first embodiment.
Therefore, below, the holding body 30 of 2nd Embodiment is mainly demonstrated and description may be abbreviate | omitted about another part.

FIG. 5 is a perspective view for explaining the holding body 30 of the second embodiment.
As shown in FIG. 5, the holding body 30 of the second embodiment is a cylindrical rod-like body that matches the shape of the circular through-hole of the circular pipe-shaped workpiece 40, and the holding body 30 is A single electrode having a length different from that of the liquid spray portion 20 can be configured.
In addition, the to-be-coated object 40 may be a square pipe shape, and the through hole of the to-be-coated object 40 is not limited to a circular shape, and may be a rectangular through hole.

  More specifically, the holding body 30 has substantially the same outer shape (outer diameter in the case of a circular shape) as the inner shape (inner diameter in the case of a circular through-hole) of the pipe-shaped object 40 and has a pipe-like shape. A portion for holding the inner surface 41 of the object to be coated 40 is formed, and this portion becomes the object to be coated holding portion 31.

  In the present embodiment, since the cylindrical holder 30 has a uniform outer diameter in the length direction, the outer peripheral surface thereof is the part to be coated holding part 31. It is not necessary to have a uniform outer diameter. For example, in the holding body 30, a taper is provided on the insertion end side where the article 40 is inserted to facilitate insertion of the article 40, and other than the portion provided with the taper. It is good also as the to-be-coated object holding | maintenance part 31 as an outer diameter substantially equal to the internal diameter of the through-hole of the to-be-coated object 40.

In the electrostatic spraying method using such a holding body 30, the object holding step is a step of attaching the object holding part 31 to the plurality of objects 40 to be stacked.
Then, after mounting the object to be coated 40 as described above, a voltage is applied between the holding body 30 and the liquid spraying unit 20 to apply the liquid to each outer surface 42 of the plurality of objects to be coated 40. Perform the landing step.

  Even in the case where the outer surface 42 of the object to be coated 40 is a liquid application scheduled portion as in the present embodiment, the electrical wiring is connected to the object to be coated 40 as the size of the object to be coated 40 decreases. In addition to this, there is a problem that it is not possible to secure a size that can serve as an electrode in the first place.

  However, since the holding body 30 has a sufficient length so as to function as an electrode having a different polarity with respect to the liquid spraying portion 20, it is possible to spray a good liquid regardless of the size of the article to be coated 40. It is possible to apply the liquid to the outer surface 42 of the object 40 that is preferably small.

As mentioned above, although this invention has been described based on specific embodiment, this invention is not limited to the said embodiment.
Although the case where the to-be-coated object 40 is mainly pipe-shaped has been described above, the to-be-coated object 40 is not limited to the pipe shape, and may be solid.
Moreover, in the above, the case where the holding body 30 hold | maintains the some to-be-coated article 40 has been shown.

Specifically, in the first embodiment, the holding body 30 holds the plurality of objects to be coated 40 in such a manner that the plurality of objects to be coated holding portions 31 formed of through holes are provided in the holding body 30, and the second embodiment Then, the length of the holding body 30 (at least the length of the portion that becomes the coating object holding portion 31) has a length that can hold the plurality of coating objects 40, so that the holding body 30 has a plurality of coating objects. The thing 40 was hold | maintained.
However, the holding body 30 only needs to have a coating object holding unit 31 that holds one coating object 40, and the coating object holding unit 31 is configured so that a plurality of coating objects 40 can be held. There is no need.

However, the holding body 30 itself has a size and length sufficient to function as a different polarity. When the object 40 is a minute-sized object, the holding body 30 includes a plurality of objects 40 to be coated. In consideration of the fact that it is possible to provide a plurality of object holding parts 31 that only hold the object, or to provide an object holding part 31 having a length that can hold the objects 40 to be coated, the holding body 30. It is not efficient to apply the liquid while holding only one object 40 to be coated.
For this reason, as in the above-described embodiment, the holding body 30 that can hold the plurality of objects to be coated 40 at a time so that the liquid can be applied to the plurality of objects to be coated 40 at one time with one holding body 30. It is preferable that

  As described above, the present invention is not limited to the above specific embodiments, and modifications and improvements as appropriate are also included in the technical scope of the present invention. Is clear from the description of the scope of claims.

DESCRIPTION OF SYMBOLS 10 Electrostatic spraying apparatus 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 Front end outer periphery 22b Opening part 23 Mandrel 23a Knob part 23b Electric wiring connection Portion 23c Male screw structure 23d End surface 24 Seal member 30 Holding body 31 Object holding part 40 Object 41 Inner surface 42 Outer surface 50 Voltage applying means 60 Grounding means 80 Tailor cone

Claims (13)

A liquid spraying section having a nozzle;
A holding body for holding an object to be partially or wholly conductive or semi-conductive and having a different polarity with respect to the liquid spraying part, and the object to be held also having a different polarity with respect to the liquid spraying part A holding body,
Voltage application means for generating an electrostatic force that causes the liquid to be detached from the nozzle in a charged state so as to apply a voltage between the liquid spraying unit and the holding body to apply the liquid to the object to be coated; With
The electrostatic spraying apparatus, wherein the holding body has a coating object holding unit that holds a part other than the liquid application scheduled part for applying the liquid of the coating object.   The electrostatic spraying device according to claim 1, wherein the holding body is made of a material that can absorb the liquid.   The said coating object holding | maintenance part is a through-hole of the inner shape substantially the same as the external shape of the said pipe-shaped to-be-coated object, and hold | maintains the outer surface of the said coating object. The electrostatic spraying device as described. The through hole is circular according to the circular outer diameter of the article to be coated,
The electrostatic spraying device according to claim 3, wherein a diameter of the through hole is set to 30 mm or less in accordance with the object to be coated having an outer diameter of 30 mm or less.   The electrostatic spraying device according to any one of claims 1 to 4, wherein the holding body includes a plurality of the object holding parts.   3. The coating object holding portion according to claim 1, wherein the coating object holding part has an outer shape substantially the same as an inner shape of the pipe-shaped coating object and holds an inner surface of the pipe-shaped coating object. The electrostatic spraying device as described. The outer shape of the coating object holding part is a circular shape corresponding to a circular through hole provided in the coated object having a maximum outer shape of 30 mm or less,
The electrostatic spraying device according to claim 6, wherein a diameter of the object holding portion is set to be less than 30 mm in accordance with an inner diameter of a through hole of the object to be coated.   The electrostatic spraying device according to claim 6 or 7, wherein the coating object holding unit has a length capable of holding a plurality of the coating objects. The coating object holding portion of the holding body that is partly or entirely conductive or semi-conductive with respect to the liquid spraying part is different from the liquid spraying part. A to-be-coated object holding step for holding a part other than the liquid application scheduled part for applying the liquid of the coating;
A coating step in which a voltage is applied between the liquid spraying unit and the holding body to cause the liquid to be detached from a nozzle of the liquid spraying unit in an electrostatic state by electrostatic force and to apply the liquid to the object to be coated. And an electrostatic spraying method. In the coated object holding step, the circular pipe-shaped coated object having an outer diameter of 30 mm or less is applied to the coated object holding portion including a through hole having substantially the same inner diameter as the outer diameter of the coated object. A step of fitting the article into the through-hole so as to hold the outer surface of the object,
The electrostatic spraying method according to claim 9, wherein the applying step is a step of applying the liquid onto an inner surface of the circular pipe-shaped object. The coating object holding step is a step of fitting a plurality of the coating objects into a plurality of the coating object holding portions including through holes provided in the holding body,
The electrostatic spraying method according to claim 10, wherein the applying step is a step of applying the liquid to each of the inner surfaces of the plurality of objects to be coated. The coated object holding step has a circular shape corresponding to a circular through hole provided in the coated object having a maximum outer shape of 30 mm or less, and an outer diameter substantially equal to the inner diameter of the through hole of the coated object. Attaching the object to be coated to the object holding part so that the object holding part has an inner surface of a through hole of the object to be coated,
The electrostatic spraying method according to claim 9, wherein the applying step is a step of applying the liquid to an outer surface of the object to be coated. The coating object holding step is a step of attaching to the coating object holding unit so as to stack a plurality of the coating objects.
The electrostatic spraying method according to claim 12, wherein the applying step is a step of applying the liquid to each of the outer surfaces of the plurality of objects to be coated.

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