JP2009226247A - Electrostatic powder coating apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electrostatic powder coating technique capable of simplifying a configuration, thinning a coating film and uniformizing the thickness of the coating film. <P>SOLUTION: In the electrostatic powder coating apparatus 1 for coating an object 10 to be coated by jetting an electrostatic powder coating material 12 from a coating gun 13 and blowing it to the object 10 to be coated, which electrically sucks the powder coating material 12, a mesh-like member 15 having many holes 15a is arranged between the object 10 to be coated and the coating gun 13. By the electrostatic powder coating apparatus 1, since the particles of the powder coating material 12 which pass through the holes 15a of the mesh-like member 15 are uniformized, the coating film of the coating in the object 10 to be coated is thinned and the thickness of the coating film is uniformized. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an electrostatic powder coating apparatus.

  In recent years, environmental pollution and bad odor due to volatile organic substances (VOC) have been a problem in painting using a paint containing an organic solvent. For this reason, in the field of coating technology, there are increasing cases of switching to powder coating not containing an organic solvent.

  As a coating technology that does not include such organic solvents, a powder gun called corona gun or tribo gun is used to eject charged powder paint from this coating gun to grounded objects (metals, conductors, etc.) A technique for spraying and attaching a powder coating by static electricity is known.

Conventionally, various electrostatic powder coating techniques have been proposed (see, for example, Patent Documents 1 and 2). The technique described in Patent Document 1 moves a coating gun along the surface of an arc-shaped workpiece, measures the distance between the coating gun and the surface of the workpiece with an ultrasonic displacement sensor, and measures the measurement data. A uniform coating thickness is obtained by controlling the movement trajectory of the coating gun based on the above. In addition, the technique described in Patent Document 2 arranges a mesh-like member to which a negative electrostatic voltage is applied in a coating gun so that negative electrostatic charges are charged when the powder paint passes through the mesh-like member. It is a thing.
JP-A-9-290182 JP-A-8-196960

  However, in the conventional electrostatic powder coating technique, it is difficult to reduce the thickness of the coating film to 40 μm or less when the particle diameter of a commonly used powder coating is about 40 μm on average. Moreover, even if the thickness of the coating film can be reduced to 40 to 50 μm, there is a problem that the variation in the thickness of the coating film becomes as large as about ± 10 μm.

  Further, the technique of Patent Document 1 has a problem that the control and configuration are complicated because it is necessary to move the coating gun up and down and back and forth by the control by the reciprocator. In the technique of Patent Document 2, a mesh-like member is provided in the coating gun to charge the powder coating with negative static electricity, and the coating film is made thin and the coating thickness is made uniform. It was difficult.

  The present invention has been made in view of such problems, and an object of the present invention is to provide an electrostatic coating technique that can simplify the configuration, reduce the thickness of the coating film, and make the thickness of the coating film uniform.

The present invention employs the following means in order to solve the above problems.
That is, the present invention
In the electrostatic powder coating apparatus for coating the object to be coated by spraying the powder paint charged with static electricity from the powder paint spraying means and spraying it on the object to be coated,
A mesh-like member having a large number of holes was disposed between the object to be coated and the powder paint spraying means.

According to the present invention, among the electrostatically charged powder paints ejected from the powder paint ejecting means, the particle diameter is excessively larger than the holes of the mesh-like members, or the mesh-like members are electrically biased and aggregated. The oversized ones collide with the surrounding parts of the mesh-like holes and are crushed, and only paint particles smaller than the holes pass through the holes and are sprayed on the object. The remaining fine particles are lightweight. Therefore, it adheres to the mesh member and is removed. In addition, paint particles that are too small compared to the holes of the mesh member ejected from the coating gun also adhere to the mesh member. Thereby, since the powder coating material which passes a mesh-shaped member becomes only what has a particle diameter in the predetermined range, the film thickness of coating can be made thin and uniform.

  Here, the mesh member can be configured to electrically suck the powder paint. According to this configuration, since the powder coating material ejected from the powder coating material ejecting means can be gathered by the mesh member, it is possible to suppress the powder coating material from being diffused in a wider range than the mesh member, thereby It is possible to prevent the paint from being wasted.

  Moreover, the said hole of the said mesh-shaped member is formed in a substantially square, The one side of the said square can be set as the structure which is 5-30 times with respect to the particle diameter in the said powder coating material. Moreover, it is preferable that the said hole of the said mesh-shaped member is formed in a substantially square, and the side of the said square is 10-15 times with respect to the particle diameter in the said powder coating material.

  The holes of the mesh member may be formed in a substantially square shape, and one side of the square may be 200 to 1200 μm. Furthermore, it is preferable that one side of the square is 400 to 600 μm. The mesh member is preferably formed of stainless steel.

The distance between the mesh member and the object to be coated is preferably 5 to 100 mm, and more preferably 20 to 50 mm.

  According to the present invention, when the powder coating material charged with static electricity is ejected from the powder coating material ejecting means, and the powder coating material passes through the mesh-shaped member, the excessive powder particles are separated by the holes of the mesh-shaped member. Since the diameter is made substantially uniform and sprayed on the object to be coated, and the excessively small particles adhere to the mesh member and are removed, the thickness of the coating film on the object to be coated can be made thin and uniform.

  Hereinafter, an electrostatic powder coating apparatus according to the best mode for carrying out the present invention (hereinafter referred to as an embodiment) will be described with reference to the drawings. The present invention is not limited to the configuration of the embodiment.

  FIG. 1 shows an electrostatic powder coating apparatus 1 according to the present invention. The electrostatic powder coating apparatus 1 ejects a powder coating 12 charged with static electricity from a coating gun 13 which is a powder coating spraying means, and sprays the powder coating 12 onto an object 10 to be electrically sucked. Thus, the object 10 is to be painted, and the mesh member 15 having a large number of holes is disposed between the object 10 and the coating gun 13.

Next, each of the above components will be described. The object to be coated 10 has a charge capable of attracting the powder coating material 12 charged with static electricity. The object to be coated 10 is suspended by, for example, a conductive member 20 and a suspension jig 11 serving as a first holding means on a top plate portion 16a of a booth 16 that is opened only on a surface facing the coating gun 13. In the present embodiment, the hanging jig 11 is formed in a substantially U shape by a rod-shaped member, and one side thereof is attached through the conductive member 20. A ground wire 17 is connected to the hanging jig 11. As a result, the charge of the object to be coated 10 becomes 0, and for example, the negatively charged electrostatic powder coating 12 is sucked. In addition, article 1
0 can be any charge as long as the powder coating 12 can be electrically sucked.

  The powder coating 12 has an average particle diameter of about 40 μm, and a powder material that does not contain an organic solvent, such as an epoxy-based, polyester-based, epoxy-polyester-based, or urethane-based powder coating, can be used. The coating gun 13 is for charging the powder coating 12 with static electricity and spraying it, and a common one such as a corona gun or a tribo gun can be used.

  The mesh member 15 is suspended from the top plate portion 16a of the booth 16 via a conductive member 21 and a suspension member 22 which is a second holding means. A ground wire 23 is connected to the mesh member 15.

  Thus, the hanging jig 11 that holds the object to be coated 10 and the hanging member 22 that holds the mesh-like member 15 are attached to the booth 16 via the conductive members 20 and 21, respectively.

  As shown in FIG. 2, the mesh member 15 is formed in a lattice shape having a large number of holes 15a. As shown in FIG. 3, the holes 15a of the mesh member 15 are formed in a substantially square shape. In addition, the hole 15a of the mesh-like member 15 is not limited to a substantially square shape, but may be various shapes such as a substantially rectangular shape or a substantially circular shape. The mesh member 15 is disposed at a position away from the object to be coated 10 by an arbitrary distance.

  For example, a sieve can be used as the mesh member 15. In this case, nylon, silk, or stainless steel sieves can be used to prevent coarse paint particles from passing through and to prevent the paint particles from adhering to the object to be coated 10. A stainless steel sieve is used to apply electrically biased paint particles (such as particles having a lot of negative charges or positive charges) to the object to be coated 10 even if the paint particles are sized to pass through the sieve. Therefore, it is possible to obtain the effect of selectively passing electrically and size uniform paint particles.

  Next, the operation of the electrostatic powder coating apparatus 1 will be described. In this electrostatic powder coating apparatus 1, since the mesh-like member 15 is disposed between the object to be coated 10 and the coating gun 13, the powder paint sprayed on the object to be coated 10 will be described below. 12 particle sizes can be made uniform (uniformized).

  That is, when the particles of the powder coating material 12 (hereinafter referred to as “powder particles”) sprayed from the coating gun 13 are excessive compared to the size of the holes 15a in the mesh member 15, the powder particles are It cannot pass through the hole 15a and remains attached to the mesh member 15, or the outer peripheral part of the powder particles is crushed by the part around the hole 15a, and becomes a size that passes through the hole 15a. 10 is sprayed. Thereby, it can suppress that the powder particle larger than the hole 15a is sprayed on the to-be-coated article 10. FIG.

  Moreover, since the fine powder particles crushed in the holes 15a are lightweight, they remain attached to the mesh member 15. On the other hand, in the powder coating material 12 ejected from the coating gun 13, powder particles that are too small compared to the holes 15 a are also light, and thus remain attached to the mesh member 15.

  In this manner, the powder particles that pass through the holes 15a of the mesh-like member 15 and are sprayed onto the object to be coated 10 are substantially uniform in terms of electrical and size. Therefore, the thickness of the coating film of the article 10 becomes uniform. Further, since the powder particles sprayed on the article 10 are sized to pass through the holes 15a of the mesh member 15, the size of the holes 15a of the mesh member 15 is set according to the size of the powder particles. By setting appropriately, the thickness of the coating film can be reduced.

  In this embodiment, since the article 10 and the mesh member 15 are electrically insulated, even if the powder coating material 12 ejected from the coating gun 13 adheres to the mesh member 15, it is baked. It can suppress sticking. Thereby, since the powder coating material 12 adhering to the mesh-like member 15 can be easily removed with an air gun or the like, the mesh-like member 15 can be reused. In addition, the electrostatic powder coating apparatus 1 simply disposes the mesh member 15 between the object to be coated 10 and the coating gun 13, and it is not necessary to move the coating gun 13 up, down, left and right. , The configuration can be simplified.

  When the object 10 has a simple shape such as a flat plate, one mesh member 15 can be used for the entire painted surface of the object 10. Further, when the shape of the article to be coated 10 is complicated and there is a possibility that the thickness of the coating film is excessively thick, the mesh member 15 is partially corresponding to the portion where the thickness of the coating film is increased. Can also be arranged. Moreover, the mesh-like member 15 from which the opening (size) of the hole 15a differs can also be used with respect to each site | part. Further, the mesh member 15 can be set to be inclined with respect to the object 10 to be coated.

  This electrostatic powder coating apparatus 1 was used to coat the object 10 and the thickness of the coating film was measured. As shown in FIG. 4, a plate member made of a steel plate having a width of 50 mm × length of 60 mm × thickness of 3 mm was used as the object to be coated 10. The suspension hole 10c has a diameter of 8 mm and is provided at a position 10 mm from the upper end. The object to be coated 10 was held by passing the hanging jig 11 through the hanging hole 10c.

  As the powder coating material 12, an epoxy coating material having an average particle size [D50%] of 40 μm, [D90%] of 130 μm, and [D99%] of 196 μm was used. The coating gun 13 is a corona gun (which causes the powder coating material 12 to be charged with negative static electricity), and the pressure of the main air is 0.01 MPa. The coating gun 13 was set with the tip of the nozzle 13 a corresponding to the center of the object to be coated 10. The distance X1 from the tip of the nozzle 13a to the object to be coated 10 is 200 mm.

  As the mesh member 15, a plain weave stainless steel sieve was used. The mesh member 15 was set between the object to be coated 10 and the coating gun 13 so as to be parallel to the object to be coated 10 at a position 40 mm away from the object to be coated 10. Further, the holes 15a of the mesh member 15 are substantially square. There are five types of sizes of the holes 15a: 106, 212, 425, 600, and 1180 μm on one side (hereinafter referred to as an opening).

  The coating thickness was an electromagnetic film thickness meter manufactured by Kett. As shown in FIG. 5, four points k1 to k4 are set at equal intervals from the lower end of the suspension hole 10c on the central axis of the article 10 as illustrated in FIG.

  6 and 7 show the measurement results S1 to S7 of the thickness of the coating film. In addition, in order to confirm the influence of the material of the mesh-shaped member 15, the thickness of the coating film when using the mesh-shaped member 15 made of nylon and having an opening of 600 μm was also measured (S5). For comparison, the thickness of the coating film without the mesh member 15 was also measured (S7).

  6 and 7, when the mesh member 15 is not used (S7), the thickness of the coating film is the smallest at the measurement point k1 closest to the suspension hole 10c of the article 10 (32. 4 μm), the tendency was that the coating thickness increased as the distance from the suspension hole 10 c increased (maximum 51.7 μm). Moreover, the variation in the thickness of the coating film was 19.3 μm at the maximum.

On the other hand, when the mesh member 15 having an opening of 106 μm is used (S1), since the opening is too small, there are few coating particles that can pass through the opening, and the coating object 10 is attached to the entire article 10 to be coated. The groundwork was exposed without wearing.

  When the mesh member 15 having a mesh opening of 212 to 1180 μm is used (S2 to S6), the coating thickness variation is smaller at each measurement point k1 to k4 than when the mesh member 15 is not used (S7). As a result, the effect that the thickness of the coating film can be made uniform by using the mesh-like member 15 was proved.

  Furthermore, when the mesh member 15 having an opening of 425 to 600 μm was used (S 3 and S 4), the variation in the coating film thickness was 14 μm at the maximum, which was the smallest among the experimental results. From this result, it was found that the opening is preferably 200 to 1200 μm, more preferably 400 to 600 μm. Thereby, since the particle diameter of the powder coating material 12 is an average of 40 micrometers, it turns out that the opening is preferably 5 to 30 times the powder particle diameter, and more preferably 10 to 15 times. Moreover, when the aperture was 212 to 1180 μm (S2 to S6), the thickness of the coating film was 20 to 50 μm, and it was found that the coating film can be thinned.

  Further, when the mesh member 15 is made of nylon, which is a non-conductive member, compared to the case where the mesh-like member 15 is made of stainless steel, both the coating film thickness and the variation are increased. From this result, it was found that the mesh member 15 made of stainless steel was more effective in uniforming the thickness of the coating film than the mesh member 15 made of nylon. In addition, the mesh-like member 15 is not limited to stainless steel, but when formed with various conductive members, it can be seen that the thickness of the coating film is more uniform than when formed with a non-conductive member such as nylon. .

  Moreover, as a result of changing the position of the mesh-like member 15 and measuring the coating film, when the distance between the mesh-like member 15 and the article to be coated 10 is 5 to 100 mm, the coating film can be uniformly and thinned, and the thickness is 20 to 50 mm. It has been found that in some cases it can be made more uniform and thinner.

It is a figure which shows the electrostatic powder coating apparatus of embodiment. It is a front view which shows the mesh-shaped member of embodiment. It is an enlarged view which shows the opening in the mesh-shaped member of embodiment. It is a perspective view which shows the to-be-coated object of an Example. It is a figure which shows the measuring point of the coating film in the to-be-coated article of an Example. It is a figure which shows the measurement result of the coating film thickness of an Example. It is a graph which shows the measurement result of the coating film thickness of an Example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Electrostatic powder coating apparatus 10 Object to be coated 10c Hole 11 Hanging jig 12 Powder coating 13 Coating gun (powder coating spraying means)
13a Nozzle 15 Mesh member 15a Hole in mesh member 16 Booth 16a Top plate portion of booth 17, 23 Ground wire 20, 21 Conductive member 22 Hanging member

Claims (9)

In the electrostatic powder coating apparatus for coating the object to be coated by spraying the electrostatically charged powder paint from the powder paint ejecting means and spraying it on the object to be coated,
An electrostatic powder coating apparatus in which a mesh-like member having a large number of holes is disposed between the object to be coated and the powder paint spraying means.   The electrostatic powder coating apparatus according to claim 1, wherein the mesh member electrically sucks the powder paint.   3. The electrostatic according to claim 1, wherein the holes of the mesh-shaped member are formed in a substantially square shape, and one side of the square is 5 to 30 times the particle diameter in the powder coating material. Powder coating equipment.   The electrostatic powder coating apparatus according to claim 3, wherein the holes of the mesh-shaped member are formed in a substantially square shape, and one side of the square is 10 to 15 times the particle diameter of the powder coating material.   The electrostatic powder coating apparatus according to any one of claims 1 to 3, wherein the holes of the mesh member are formed in a substantially square shape, and one side of the square is 200 to 1200 µm.   The electrostatic powder coating apparatus according to claim 5, wherein one side of the square is 400 to 600 μm.   The electrostatic powder coating apparatus according to claim 1, wherein the mesh member is formed of a conductive member.   The electrostatic powder coating apparatus according to any one of claims 1 to 7, wherein a distance between the mesh member and the object to be coated is 5 to 100 mm.   The electrostatic powder coating apparatus according to claim 8, wherein a distance between the mesh member and the object to be coated is 20 to 50 mm.

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