JP2000126653A - Rotary atomizing coating device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a rotary atomizing coating device by which a hue of coating material can be a proper hue without deteriorating adhesive efficiency in coating. SOLUTION: A rotary atomizing coating device 100 is provided with a rotatable bell cup 30 to whose inner peripheral surface 32 coating material P is fed, an air diffuser 46 which is opened along the periphery on the rear side of the bell cup, feeding shaping air S forward from the rear side and deflecting atomized coating material discharged from the head of the inner peripheral surface of the ball cup to a surface to be coated, and an air guide member 40 disposed between the bell cup 30 and the air diffuser 46, having an air guiding surface 42 whose protrusion is in contact with the end 38 of the bell cap.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rotary atomizing electrostatic coating apparatus, and more particularly to a rotary atomizing coating apparatus capable of maintaining a coating efficiency and maintaining an appropriate color by considering a blowing direction of shaping air. Related to the device.

[0002]

2. Description of the Related Art A rotary atomizing electrostatic coating apparatus using a bell cup has been conventionally known as a coating apparatus for an automobile body or an automobile part. In this type of rotary atomizing electrostatic coating apparatus, a voltage of about -60 kV is applied and 35,000 r.
When the paint is supplied to the inner peripheral surface of the bell cup which rotates at a high speed of about pm, the paint reaches the tip of the inner peripheral surface of the bell cup due to centrifugal force. Jump out towards. At this time, shaping air is supplied from the back of the bell cup to collect the sprayed charged particles toward the object to be coated and form an efficient ring-shaped coating pattern (for example, see Japanese Patent Application Laid-Open No. 9-285742). ).

Here, the surface quality of the painted surface, such as the coating surface and the sharpness, is improved as the particle size of the coated particles is smaller, that is, as the atomization rate is higher. Therefore, it is said that it is preferable to rotate the bell cup at high speed in order to improve the surface quality of the painted surface.

However, when the bell cup is rotated at a high speed, the center of the inner peripheral surface of the bell cup becomes a negative pressure, the surrounding air is entrained, and this air is again pushed out to the tip of the inner peripheral surface of the cup by centrifugal force. The paint supplied to the inner peripheral surface has a strong tendency to fly outward in the radial direction of the bell cup due to the flow of the air. In this case, if the shaping air from the back of the bell cup is strengthened to deflect the coating particles forward, the amount of the coating particles rebounding on the surface of the workpiece increases, so that the scattered paint increases and the coating efficiency increases. There was a problem of lowering.

In view of the above, there has been previously proposed a coating apparatus in which air is separately blown from a circumference having a diameter larger than that of the bell cup to deflect the coating particles which have protruded outward in the radial direction of the bell cup. See JP-A-10-52656).

[0006]

However, the rotary atomizing coating apparatus using the air guide described above has improved coating efficiency as compared with the conventional rotary atomizing coating apparatus, but it is difficult to apply a flat coating such as a metallic coating. When a paint containing a pigment (such as an aluminum pigment or a mica pigment) was applied, a phenomenon was observed in which the color was insufficient and the color became slightly dark. For this reason, it was necessary to provide a separate painting process and a painting machine in order to match such a color tone to an appropriate one.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems of the prior art, and provides a rotary atomizing coating apparatus capable of giving a proper tint of a coating without reducing coating efficiency. With the goal.

[0008]

(1) In order to achieve the above object, a rotary atomizing coating apparatus according to claim 1 comprises: a rotatable bell cup for supplying paint to an inner peripheral surface; An air outlet that is opened along the periphery of the back side of the cup and supplies shaping air from the back side to the front, and is provided with an atomized paint discharged from the tip of the inner peripheral surface of the bell cup. In the rotary atomizing coating apparatus for deflecting the surface of the bell cup, the air guide member further includes an air guide member provided between the bell cup and the air outlet, the extension of which has an air guide surface in contact with the forefront of the bell cup. It is characterized by the following.

In the rotary atomizing coating apparatus according to the first aspect of the invention, the shaping air is supplied from the back of the bell cup so as to be in contact with the forefront of the bell cup, thereby containing aluminum pigment, mica pigment and other flat pigments. The color of the paint can be applied to an appropriate color.

[0010] In addition, by supplying shaping air so as to be in contact with the forefront of the bell cup, the pattern distribution by the bell cup is almost flat, so that uniformity of the film thickness can be expected and the pattern width can be compared. Therefore, even if the moving speed of the bell cup is relatively low, a sufficient number of times of coating can be secured.

(2) In the rotary atomizing coating apparatus according to the first aspect, the angle at which the shaping air contacts the tip of the bell cup is not particularly limited. The guide surface is characterized in that its extension line contacts the front end of the bell cup at an angle of 0 ° or more and 4 ° or less. That is, the shaping air is 0 ° -4 ° with respect to the tip of the bell cup.
It is more preferable to make contact at an angle of, in particular, 0 °. Here, the angle refers to the angle θ shown in FIG.

If the angle exceeds 4 °, the coating efficiency and the change in color tone are not particularly affected (not improved but not reduced), but the air guiding surface necessarily has a large angled cone. Face. For this reason, when manufacturing the air guide member, it is necessary to process the extension of the air guide surface so as to accurately contact the forefront of the bell cup. is there. Conversely, if this angle is less than 0 °, that is, a negative angle, the pattern width by the bell cup becomes too wide, and if the moving speed of the bell cup is made relatively low, there is a possibility that a sufficient number of coating times cannot be secured. is there.

In particular, when the shaping air is supplied in parallel to the tip of the bell cup, there is no effect even if the distance between the air outlet of the shaping air and the tip of the bell cup is slightly changed. It is not necessary to pay much attention to the processing accuracy of the parts other than the air guide surface when manufacturing the device. Further, by supplying the shaping air so as to be in contact with the forefront of the bell cup, it is possible to prevent adhesion of the coating particles to the back surface of the bell cup.

(3) In the rotary atomizing coating apparatus according to the first or second aspect, the specific means for supplying the shaping air so as to be in contact with the tip of the bell cup is not particularly limited. For example, in the rotary atomization coating apparatus according to the third aspect, the air guide member is a cylindrical body having an outer diameter equal to the outermost diameter of the bell cup. According to a fourth aspect of the present invention, in the rotary atomizing coating apparatus, the air guide member is a part of a cone having an outer diameter larger than the outermost diameter of the bell cup.

The above operation and effect can be exhibited by forming the air guide member for guiding the shaping air to the tip of the bell cup with a part of a cylindrical body or a conical body.

(4) In the rotary atomizing coating apparatus according to any one of claims 1 to 4, the shape of the air outlet is not particularly limited. For example, in the rotary atomizing coating apparatus according to the fifth aspect, the air outlet comprises a plurality of round holes. According to a sixth aspect of the present invention, in the rotary atomizing coating apparatus, the air outlet comprises an annular slit having the air guide surface as an inner peripheral wall.

Regardless of whether the air outlet is a round hole or an annular slit, the above-described improvement in coating efficiency and optimization of color can be achieved.

(5) In the case where the air outlet is constituted by an annular slit as in the rotary atomizing coating apparatus according to the sixth aspect, there is no particular limitation, but in the rotary atomizing coating apparatus according to the seventh aspect, And a cover member that forms an outer peripheral wall of the annular slit and has an angle (indicated by α in FIG. 1) formed between the outer peripheral surface and the air guide surface of less than 45 °. I do.

By forming the outer peripheral surface of the member located on the back of the bell cup toward the tip at an acute angle of less than 45 °,
The turbulence of the shaping air can be prevented, whereby the angle of deflection of the coating particles can be made appropriate and the scattering of the coating particles can be prevented.

(6) In the case where the air outlet is constituted by an annular slit as in the rotary atomizing coating apparatus according to the sixth or seventh aspect, the slit width is not particularly limited. In the atomizing coating apparatus, the width of the slit is 1 mm or less.

If the slit width exceeds 1 mm, the guiding effect of the air guiding surface is reduced, and turbulence tends to occur in the shaping air.

(7) In the case where the air outlet is constituted by an annular slit as in the rotary atomizing coating apparatus according to any one of claims 6 to 8, the rotary atomizing coating apparatus according to claim 9 is not particularly limited. The thickness of the tip of the cover member is within 5 times the width of the slit.

By setting the thickness of the tip of the cover member located on the back of the bell cup to within 5 times the slit width,
The turbulence of the shaping air can be prevented, whereby the angle of deflection of the coating particles can be made appropriate and the scattering of the coating particles can be prevented.

(8) In the rotary atomizing coating apparatus according to any one of claims 1 to 9, the applicable paint is not particularly limited.
It can be used as a coating device for solid paint, clear paint, base paint and all other paints. Further, the present invention can be applied not only to the top coating process but also to the intermediate coating paint in the intermediate coating process.

In particular, when the paint is a paint containing a flat pigment as in the rotary atomizing coating apparatus according to the tenth aspect, the effect of optimizing the color tone becomes remarkable.

[0026]

According to the first to tenth aspects of the present invention, it is possible to coat a paint containing an aluminum pigment, a mica pigment, and other flat pigments with an appropriate tint. In addition to this, by supplying shaping air so as to be in contact with the forefront of the bell cup, the pattern distribution by the bell cup is almost flat and uniformity of film thickness can be expected, and the pattern width is relatively wide. Thus, even if the moving speed of the bell cup is relatively low, it is possible to secure a sufficient number of application times.

According to the second aspect of the present invention, the manufacturing cost of the air guide member can be reduced.

Further, according to the invention of claims 6 to 9,
The turbulence of the shaping air can be prevented, whereby the angle of deflection of the coating particles can be made appropriate and the scattering of the coating particles can be prevented.

[0029]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a cross-sectional view showing an embodiment of the rotary atomizing coating apparatus of the present invention, FIG. 2 is a half-sectional view showing another embodiment of the rotary atomizing coating apparatus of the present invention, and FIG. It is a half sectional view showing a comparative example of a coating device.

As shown in FIG. 1, a rotary atomizing electrostatic coating apparatus 100 of the present embodiment includes a rotating shaft 20 inside a housing 10.
Are rotatably supported by a motor (not shown), and a bell cup 30 is fixed to a tip of the rotating shaft 20 at a bell hub portion 34. The bell cup 30 is rotated at a high speed of, for example, about 35,000 rpm during painting.

A plurality of paint holes 36 are formed in the gap between the inner peripheral surface 32 of the bell cup 30 and the bell hub portion 34, and the bell hub portion 34 extends from the tip of the paint nozzle 50 inserted through the rotating shaft 20. Is supplied to the inner peripheral surface 32 of the bell cup 30 through the paint holes 36. Although not shown, fine irregularities are formed at the tip of the inner peripheral surface 32 of the bell cup 30 to atomize the paint P spread in a liquid film along the inner peripheral surface 32. I have. The applied voltage circuit is connected to the rotating shaft 20, and a DC voltage of, for example, about −60 kV is applied to the bell cup 30 via the rotating shaft 20.

In the rotary atomizing electrostatic coating apparatus of the present embodiment,
An air guide member 40 is fixed between the housing 10 and the bell cup 30.
An air guide surface 42 is formed over the entire outer surface of the device.

The air guide member 40 is inserted into the housing 10 via the O-ring 12. At this time, the air guide member 40 is fixed to the housing 10 by screwing into the housing cover 14 provided outside the housing 10. .

An annular air passage 16 is formed between the housing 10 and the housing cover 14. The annular air passage 16 communicates with a plurality of air passages 44 formed in the air guide member 40. Further, the air passage 44 communicates with an air outlet 46 described later.

The air outlet 46 of this embodiment is formed by an annular slit having the air guide surface 42 of the air guide member 40 as an inner peripheral surface and the inner surface of the cover member 48 as an outer peripheral surface. That is, by screwing the air guide member 40 into the housing cover 14 and then screwing the cover member 48 outside the air guide member 40,
A slit-shaped air outlet 46 is formed between the cover member 48 and the air guide surface 42 of the air guide member 40, and shaping air supplied from the air passages 16 and 44 is supplied from the air outlet 46 to the bell cup 30.
Blow out in a ring toward.

Although not particularly limited, the slit width of the slit-shaped air outlet 46 is desirably 1 mm or less. If the slits are wider than this, the air guiding effect by the air guiding surface 42 is reduced, and turbulence is likely to occur in the shaping air S. The outer surface of the cover member 48 is desirably formed so that the angle α formed with the air guide surface 42 is an acute angle of less than 45 °. By doing so, the turbulence of the shaping air can be prevented, the deflection angle of the coating particles can be optimized, and the scattering of the coating particles can be prevented. Furthermore, it is desirable that the thickness of the tip of the cover member 48 be within 5 times the slit width, that is, 5 mm or less. This also prevents the turbulence of the shaping air S, makes it possible to optimize the angle of deflection of the coating particles, and also prevents the scattering of the coating particles.

Particularly, in this embodiment, the air guide member 4
0 is formed as a cylindrical body having an outer diameter equal to the outer diameter of the foremost (most foremost edge) 38 of the bell cup 30, so that the compressed air introduced from the air passages 16 and 44 is formed by a slit. From the air outlet 46 to the tip of the bell cup 30 and from the tip 38
Is discharged as shaping air S in contact with

Next, the operation will be described. In the present embodiment, when the paint P is supplied from the paint nozzle 50 to the back surface of the bell hub portion 34 by rotating the bell cup 30, the bell cup 30
Due to the rotational centrifugal force, the paint P passes through the paint hole 36 and spreads on the inner peripheral surface 32 of the bell cup 30 in the form of a liquid film to reach the tip. The charged coating particles fly outward in the radial direction of the bell cup 30 while being atomized by fine irregularities formed at the tip of the inner peripheral surface of the bell cup 30.

At this time, the shaping air S blown out from the air blowout port 46 flows along the air guide surface 42 of the air guide member 40 and is blown out parallel and in contact with the tip 38 of the bell cup 30. Then, the above-mentioned coating particles are deflected at the tip end 38 of the bell cup 30 toward the object to be coated.

As described above, the coating pattern of the coating particles is determined by the balance between the rotational centrifugal force of the bell cup 30 and the flow rate of the shaping air S. In the rotary atomizing electrostatic coating apparatus 100 of the present embodiment, the shaping is performed. The air S is supplied from the back of the bell cup 30 to the front end 38 of the bell cup 30.
Since the paint is supplied so as to be in contact with the pigment, it is possible to prevent the problem that the paint containing the aluminum pigment, the mica pigment, and the other flat pigment becomes darkened.

In addition, by supplying the shaping air S so as to be in contact with the foremost end 38 of the bell cup 30, the pattern distribution by the bell cup 30 becomes almost flat, and as a result, uniformity of the film thickness is expected. it can. Also,
Since the pattern width is relatively wide, even if the moving speed of the bell cup 30 is relatively low, a sufficient number of times of application can be secured.

Further, in the rotary atomizing electrostatic coating apparatus of the present embodiment, the air guiding surface 42 is formed in a cylindrical shape so as to supply the shaping air S in parallel to the foremost end 38 of the bell cup 30. Even if the axial distance between the air outlet 46 of the shaping air and the foremost end 38 of the bell cup 30 slightly changes, the influence is small. Therefore, when manufacturing the air guide member 40, the air guide surface 42
The machining accuracy of the part other than making the outer diameter of the front end 38 of the bell cup 30 equal to that of the bell cup 30 does not need to be considered so much, and the manufacturing cost can be reduced.

Further, by supplying the shaping air S so as to be in contact with the foremost end 38 of the bell cup 30, the adhesion of the coating particles to the back surface of the bell cup 30 can be minimized. In contrast, in the rotary atomizing coating apparatus 100 according to the comparative example shown in FIG. 3, the shaping air S blown out from the air blowout port 46 and flowing down along the air guide surface 42 blows out to the back surface of the bell cup 30. Is done.
According to this kind of shaping air S, bell cup 3
0 can be suitably prevented from adhering to the back surface, but if the pattern width is too wide and the moving speed of the bell cup is relatively low, it may not be possible to secure a sufficient number of coatings.

The present invention is not limited to the embodiment shown in FIG. 1 at all, and various modifications are conceivable. For example, in the rotary atomizing electrostatic coating apparatus 100 of the present invention shown in FIG. 2, the air guide surface 42 formed on the air guide member 40 has a slight inclination angle θ with respect to the foremost end 38 of the bell cup 30. These examples are also within the scope of the present invention.

In this case, the air guide member 40 is formed not as a cylindrical body but as a part of a conical body, and the air guide surface is positioned so that the tip 38 of the bell cup 30 is located on the extension of the air guide surface 42. 42 angles, bell cup 3
The axial distance between 0 and the air guide member 40 is set. The angle θ formed by the air guide surface 42 is determined in consideration of the manufacturing accuracy and the manufacturing cost of the air guide member 40.
It is desirable that it is 4 ° or less.

In the rotary atomizing electrostatic coating apparatus thus configured, similarly to the above-described embodiment, the shaping air S is supplied from the back surface of the bell cup 30 so as to be in contact with the foremost end 38 of the bell cup 30. Accordingly, it is possible to prevent a problem that the paint containing the aluminum pigment, the mica pigment, and the other flat pigments becomes dark in color.

In addition, by supplying the shaping air S so as to be in contact with the foremost end 38 of the bell cup 30, the pattern distribution by the bell cup 30 becomes almost flat, and as a result, uniformity of the film thickness is expected. it can. Also,
Since the pattern width is relatively wide, even if the moving speed of the bell cup 30 is relatively low, a sufficient number of times of application can be secured.

The embodiments described above are described for facilitating the understanding of the present invention, and are not described for limiting the present invention. Therefore, each element disclosed in the above embodiment is intended to include all design changes and equivalents belonging to the technical scope of the present invention.

For example, in the above-described embodiment, the air outlet 46 for blowing out the shaping air S is formed by an annular slit. However, in the present invention, a plurality of circular holes scattered around the circumference are used instead. Also, an intermittent annular slit or the like can be appropriately adopted.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an embodiment of a rotary atomizing coating apparatus according to the present invention.

FIG. 2 is a half sectional view showing another embodiment of the rotary atomizing coating apparatus of the present invention.

FIG. 3 is a half sectional view showing a comparative example of the rotary atomizing coating apparatus of the present invention.

[Description of Signs] 100 ... Rotary atomizing coating device 30 ... Bell cup 32 ... Inner peripheral surface 34 ... Bell hub 36 ... Paint hole 38 ... Cutting edge 40 ... Air guide member 42 ... Air guide surface 44 ... Air passage 46 ... Air blowing Exit 48: Cover member

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 4D075 AA13 AA78 AA85 EA05 4F033 BA03 CA03 NA01 PB01 4F034 AA04 BA22 BB28 CA25 DA06 DA23

Claims (10)

[Claims] 1. A rotatable bell cup for supplying paint to an inner peripheral surface thereof, and an air outlet opening along a periphery of a back side of the bell cup and supplying shaping air forward from the back side. In the rotary atomizing coating device for deflecting the atomized paint discharged from the inner peripheral surface tip of the bell cup to the surface to be coated, provided between the bell cup and the air outlet,
The rotary atomizing coating apparatus further comprising an air guide member having an air guide surface whose extension is in contact with the tip of the bell cup. 2. The rotary atomizing coating apparatus according to claim 1, wherein the extension line of the air guiding surface contacts an end of the bell cup at an angle of 0 ° or more and 4 ° or less. . 3. The rotary atomizing coating apparatus according to claim 1, wherein said air guide member is a cylindrical body having an outer diameter equal to the outermost diameter of the tip of said bell cup. 4. The rotary atomizing coating apparatus according to claim 1, wherein said air guide member is a part of a cone having an outer diameter larger than the outermost diameter of the bell cup. . 5. A rotary atomizing coating apparatus according to claim 1, wherein said air outlet comprises a plurality of round holes. 6. A rotary atomizing coating apparatus according to claim 1, wherein said air outlet comprises an annular slit having said air guide surface as an inner peripheral wall. 7. An outer peripheral wall of said annular slit is formed,
7. The rotary atomizing coating apparatus according to claim 6, further comprising a cover member in which an angle formed between the outer peripheral surface and the air guiding surface is less than 45 degrees. 8. A rotary atomizing coating apparatus according to claim 6, wherein said slit has a width of 1 mm or less. 9. The apparatus according to claim 6, wherein a thickness of a tip of said cover member is within five times a width of said slit.
9. The rotary atomizing coating apparatus according to any one of 8. 10. The rotary atomizing coating apparatus according to claim 1, wherein the coating is a coating containing a flat pigment.