JPH08196947A - Rotary atomizing type coating device and coating method - Google Patents

Abstract

(57) [Summary] [Purpose] In a rotary atomization type coating device, both reduction of outer mist and reduction of bounce of shaping air on the object to be coated are achieved at the same time, and the mixed material is mixed in the coating material. In this case, the mixed material is uniformly attached to the object to be coated without being sorted. A rotary atomizer 12 and an air blowing passage 70 for blowing shaping air from the outer peripheral side of the rotary atomizer 12 are provided. The pressure of the shaping air blown from the air blowing passage 70 is controlled by air pressure. By the alternate switching means 60, for example, 1
High pressure and low pressure are alternately switched at high speed of several tens of times per second.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rotary atomizer for atomizing and discharging paint by rotating, and an air blowing passage for blowing shaping air from the outer peripheral side of the rotary atomizer. The present invention relates to an atomizing type coating device and a coating method.

[0002]

2. Description of the Related Art Conventionally, a rotary atomizer that atomizes paint by centrifugal force by rotating and discharges it radially outward, and shaping air is blown from the outer peripheral side of the rotary atomizer. There is known a rotary atomizing type coating apparatus including an air blowing passage for directing a flow of atomized paint discharged outward in the radial direction toward an object to be coated.

A conventional general rotary atomization type coating apparatus is provided with a single air blow passage on the outer peripheral side of the rotary atomizer, that is, one annular air blow passage. 58
In Japanese Patent Laid-Open No. 104656, there is provided a double air blowing passage which is provided with a predetermined distance in the radial direction and has the same air blowing direction, and the shaping air is blown in two stages at such distant positions. What has been done is proposed.

[0004]

By the way, in the rotary atomizing type coating apparatus, the atomized coating material discharged outward in the radial direction by the centrifugal force as described above is directed by the shaping air toward the object to be coated. Therefore, if the shaping air pressure is small (the blowing speed is low and the blowing amount is small), the atomized paint discharged in the radial direction due to the centrifugal force cannot be sufficiently oriented, and the atomized paint The amount of so-called outer mist, which penetrates the shaping air and scatters outward in the radial direction, increases the coating efficiency and increases the shaping air pressure to suppress this outer mist (the blowing speed is high and the If the amount is large), the amount of shaping air bounced on the object to be coated will increase, preventing the paint from adhering to the object to be coated, resulting in low coating efficiency. Since, it is extremely difficult both to satisfy the conflicting requirements of reducing the reduction and shaping air rebound of the outer mist.

Further, when a mixed material such as a glittering material and an interference coloring material is mixed in the paint as in the case of metallic coating, when the paint spreads in the radial direction by centrifugal force, the mixed material is mixed. Depending on the weight, for each mixed material, that is, for each size of mixed material of the same type only, if multiple types of mixed material with different specific gravities are contained, the degree of spread differs for each type and size, There is also a problem that the mixed material adheres to different positions on the surface of the article to be coated in a state where the mixed material is sorted according to its type and size, which causes uneven color.

[0006] Therefore, as described in the above publication, the air blowing passages are provided in double, the outer air blowing passages are arranged at a position separated from the inner air blowing passages by a predetermined length, and shaping is performed in two steps. According to the air blower, the velocity of the atomized paint to the outside in the radial direction is considerably small at the position where it reaches the outer air blow passage, so that low pressure air with little rebound from the outer air blow passage It is possible to sufficiently control the direction of the atomized paint flow and suppress the outer mist, and thus it is possible to satisfy the requirements for both the reduction of the outer mist and the reduction of the bounce of the shaping air to some extent.

However, in the case of this device, in order to satisfy such conflicting requirements, it is necessary to dispose the outer air blowing passage at a position separated from the inner air blowing passage by a predetermined length as described above. Therefore, there is a problem in that the coating apparatus becomes large due to this.

Also, in this apparatus, the problem that the mixed material adheres to the article to be coated in a state of being sorted according to the type and size of the mixed material and causes color unevenness has not been solved at all.

In view of the above circumstances, an object of the present invention is to satisfy both contradictory requirements of reducing the outer mist and reducing the bounce of shaping air without increasing the size of the apparatus, and at the same time, to prevent the material mixed in the paint. It is an object of the present invention to provide a rotary atomizing type coating apparatus and a coating method capable of evenly adhering a mixed material to an object to be coated without being sorted even if the mixed material is mixed.

[0010]

In order to achieve the above object, a first rotary atomizing type coating apparatus according to the present invention is provided with a rotary atomizer for atomizing and discharging a coating material by rotating the rotary atomizing apparatus. A rotary atomization type coating device having an air blowing passage for blowing shaping air from the outer peripheral side of the atomizer,
It is characterized by comprising an air pressure alternate switching means for alternately switching the pressure of the shaping air blown out from the air blowing passage between a high pressure and a low pressure.

A second rotary atomizing coating apparatus according to the present invention is the same as the first rotary atomizing coating apparatus, wherein the air blowing passages are multiply arranged at different radial positions. Each of the air blowing directions is composed of a plurality of air blowing passages different from each other, and the air pressure alternate switching means alternately changes the pressure of the shaping air blown out from the air blowing passage located outside in the radial direction into high pressure and low pressure. The third rotary atomizing coating device according to the present invention is characterized in that the air is blown out from the air blowing passage located inside in the radial direction in the second rotary atomizing coating device. A fourth rotary atomizing coating apparatus according to the present invention is characterized in that the pressure of shaping air is substantially constant, and
The air blowing passages are multiply arranged at different positions in the radial direction, and each air blowing direction is composed of a plurality of air blowing passages different from each other, and the air pressure alternate switching means is located inside the radial direction. The pressure of the shaping air blown out from the air blowing passage is alternately switched between high pressure and low pressure.

According to a fifth rotary atomizing coating apparatus of the present invention, in the fourth rotary atomizing coating apparatus, the pressure of shaping air blown out from the air blowing passage located on the outer side in the radial direction is substantially the same. It is characterized by being constant.

A sixth rotary atomizing type coating apparatus according to the present invention is the same as the first rotary atomizing type coating apparatus, wherein the coating material is mixed with a mixed material such as a glitter material and an interference coloring material. Is characterized in that.

In order to achieve the above object, the first coating method according to the present invention has a rotary atomizer for atomizing and discharging the paint by rotating, and shaping air from the outer peripheral side of the rotary atomizer. A coating method for coating an object to be coated using a rotary atomizing coating device comprising an air blowing passage for blowing air, wherein the pressure of shaping air blown out from the air blowing passage is alternately high pressure and low pressure. The feature is that the object to be coated is painted while switching.

A second coating method according to the present invention is the above first method.
In the coating method, the air blowing passages are multiply arranged at different positions in the radial direction, and each of the air blowing directions is composed of a plurality of air blowing passages different from each other. It is characterized in that the object to be coated is coated while the pressure of the shaping air blown out from the passage is alternately switched between high pressure and low pressure.

A third coating method according to the present invention is the above first method.
In the coating method, the air blowing passages are multiply arranged at different positions in the radial direction, and each air blowing direction is composed of a plurality of air blowing passages which are different from each other. It is characterized in that the object to be coated is coated while the pressure of the shaping air blown out from the passage is alternately switched between high pressure and low pressure.

A fourth coating method according to the present invention is the above first method.
In the coating method, the coating material is a coating material mixed with a mixing material such as a glitter material and an interference coloring material.

The low pressure in "alternately switching the pressure of shaping air between high pressure and low pressure" is zero.
That is, it is meant to include stopping the blowing.

[0019]

As described above, the first rotary atomizing type coating apparatus according to the present invention has the air pressure alternating means for alternately switching the pressure of the shaping air blown from the air blowing passage between the high pressure and the low pressure. Since the switching device is provided, when the shaping air pressure is constant as in the conventional device, if the pressure is high, the rebound increases, and if the pressure is low, the outer mist increases. By alternately switching to low pressure, for example, switching at a high speed such as 20 times per second, it is possible to balance the bounce and the outer mist and suppress both of them, thus improving the coating efficiency. .

More specifically, by alternately switching between high pressure and low pressure, the outer mist seems to increase at low pressure, but since it can be switched in an extremely short cycle, the pressure immediately changes from low pressure to high pressure. The increase in mist is suppressed, and if the pressure remains high, the flow velocity of the shaping air increases and the rebound increases, but by alternately switching between high pressure and low pressure, even if the flow velocity increases at high pressure, the low pressure immediately causes The flow velocity is reduced, and the increase in flow velocity is sufficiently suppressed and the increase in rebound is also suppressed as a whole, so that both outer mist and rebound are reduced in a well-balanced manner, and coating efficiency can be improved.

Further, as in the case where the paint is a paint for metallic coating, for example, a luster material (aluminum, glass flakes, etc.)
When a mixed material such as an interference color material (mica, etc.) is mixed, the weight of the mixed material is changed according to the switching between the high pressure and the low pressure by alternately switching the air pressure between high pressure and low pressure. The degree of spread changes repeatedly according to the above, whereby the stirring effect of the mixed material is obtained, and the mixed materials of different types and sizes are stirred and uniformly attached on the object to be coated,
Color unevenness can also be reduced.

As described above, the second rotary atomizing type coating apparatus according to the present invention is the same as the first rotary atomizing type coating apparatus,
The air blowing passages are multiply arranged at different positions in the radial direction, and each of the air blowing directions is a plurality of air blowing passages which are different from each other. Since the pressure of the shaping air blown out from the air blowing passage is alternately switched between high pressure and low pressure, it is possible to more efficiently achieve the above-mentioned improvement in coating efficiency and reduction in color unevenness.

For example, as described above, the air blowing passage is provided in two
When it is provided in a heavy manner, the shaping air is blown from the inner air blowing passage at a more angle, that is, it is blown toward the inside of the rotary atomizer to mainly suppress the outer mist and reduce the blowing pressure at that time. As a result, the bounce is prevented and the atomizing paint is mainly directed to the object by the shaping air blown from the air blowing passage on the outer side, and in this case, the air blown on the outside is blown out. By alternately switching the pressure of the shaping air blown out from the passage between the high pressure and the low pressure, the atomized paint can be sufficiently oriented while suppressing the increase of the flow velocity and preventing the rebound as described above.

It should be noted that the effect of being able to carry out sufficient orientation while suppressing the bounce due to the alternate switching of the air pressure is that, for example, if the air pressure is made low to suppress the bounce, the air will not reach the object to be coated sufficiently. Compared with the difficulty of directing the atomized paint within a narrow range, it can be understood more clearly.

As described above, the third rotary atomizing type coating apparatus according to the present invention is the same as the second rotary atomizing type coating apparatus.
Since the pressure of the shaping air blown from the air blowing passage located on the inner side in the radial direction is set to be substantially constant, when the pressure of the shaping air blown from the inner air blowing passage is also switched alternately between high pressure and low pressure. In comparison, the outer mist can be further suppressed.

As described above, the fourth rotary atomization type coating apparatus according to the present invention is the same as the first rotary atomization type coating apparatus,
The air blowing passages are multiply arranged at different positions in the radial direction, and each of the air blowing directions is a plurality of air blowing passages different from each other. Since the pressure of the shaping air blown out from the air blowing passage is alternately switched between high pressure and low pressure, it is possible to more efficiently achieve the above-mentioned improvement in coating efficiency and reduction in color unevenness.

For example, as described above, the air blowing passage is provided in two
When it is provided with a heavy weight, the shaping air is blown from the inner air blowing passage at a more angle, that is, it is blown toward the inside of the rotary atomizer to suppress the outer mist and at the same time, the blowing pressure is high. By alternately switching between high pressure and low pressure, as described above, the atomized paint is sufficiently directed to the object to be coated while suppressing the increase in the flow velocity and preventing rebound, and Then, the shaping air is blown out from the outside air blowing passage at a low pressure, so that the outer mist that has passed the shaping air blown out from the inside air blowing passage while preventing rebound is formed from this outside air blowing passage. Thus, it is possible to orient the material toward the article to be coated and sufficiently suppress outer mist.

As described above, the fifth rotary atomization type coating apparatus according to the present invention is the same as the fourth rotary atomization type coating apparatus.
Since the pressure of the shaping air blown out from the air blowing passage located on the outer side in the radial direction is made substantially constant, when the pressure of the shaping air blown out from the air blowing passage on the outside is also switched alternately between high pressure and low pressure. In comparison, the outer mist can be further suppressed.

A sixth rotary atomization type coating apparatus according to the present invention is the same as the first rotary atomization type coating apparatus, in which the above-mentioned coating material is mixed with a mixed material such as a glitter material and an interference coloring material. Therefore, in this case, as described above, by alternately switching the high pressure and the low pressure, the degree of spread corresponding to the weight of the mixed material is repeatedly changed according to the switching between the high pressure and the low pressure, and thus, The effect of stirring the mixed material is obtained, and mixed materials of different types and sizes are stirred and uniformly attached on the object to be coated, and color unevenness can be reduced.

When the air blowing passages are provided in double, either the pressure of the shaping air blown from the inner air blowing passage or the pressure of the shaping air blown from the outer air blowing passage is set to a high pressure. The effect of reducing the color unevenness can be obtained even when the pressure is alternately switched to the low pressure, but the blowing pressure of the shaping blown out from the air blowing passage inside the rotary atomizer is alternately switched between the high pressure and the low pressure. In the case of switching, the mixed material can be more effectively agitated, and a further color unevenness reducing effect can be obtained. Further, in this case, the shaping air blown out from the outside air blowing passage can be made to have a substantially constant pressure, so that the flow velocity can be increased as compared with the case where the high pressure and the low pressure are alternately switched. It can be pressed against the object to be coated with a large force, and as a result, the orientation of the mixed material is improved, and the effect of further reducing color unevenness can be obtained.

The first coating method according to the present invention is, as described above, a rotary atomizer that atomizes and discharges the paint by rotating, and an air that blows shaping air from the outer peripheral side of the rotary atomizer. A method of coating an object to be coated using a rotary atomization type coating device comprising a blow-out passage, wherein the pressure of shaping air blown out from the air blow-out passage is alternately switched between high pressure and low pressure. Since the object to be coated is coated, the same effect as that of the first rotary atomization type coating device can be obtained.

As described above, the second coating method according to the present invention is the same as the first coating method, except that the air blowing passages are multiply arranged at different positions in the radial direction and the respective air blowing passages are arranged. It consists of a plurality of air blowing passages having different blowing directions, and the pressure of shaping air blown out from the air blowing passage located on the outer side in the radial direction is changed over between high pressure and low pressure to coat the object to be coated. The same effect as the second rotary atomizing type coating device can be obtained.

As described above, the third coating method according to the present invention is the same as the first coating method, in which the air blowing passages are multiply arranged at different positions in the radial direction and the respective air blowing paths are arranged. It consists of a plurality of air blowing passages having different blowing directions, and since the pressure of shaping air blown from the air blowing passage located on the inner side in the radial direction is alternately switched between high pressure and low pressure, the object to be coated is coated. The same effect as that of the fourth rotary atomization type coating device can be obtained.

As described above, the fourth coating method according to the present invention is the above-mentioned first coating method, wherein the coating material is a coating material mixed with a mixing material such as a glitter material and an interference coloring material. The same operation and effect as those of the sixth rotary atomizing type coating device can be obtained.

[0035]

Embodiments of the present invention will now be described in detail with reference to the drawings.

[Apparatus Configuration] FIG. 1 is a sectional view showing an embodiment of the rotary atomizing coating apparatus according to the present invention (a sectional view taken along the line I--I of FIG. 2), and FIG. 2 is a plan view of the apparatus shown in FIG. Figure, Figure 3
FIG. 3 is a sectional view taken along line III-III.

The illustrated rotary atomization type coating device 10 includes a rotary atomizer 12 for ejecting atomized paint radially outward, and a fog ejected from the rotary atomizer 12 radially outward. Air blowing passage 70 for blowing shaping air for directing the flow of the chemical paint toward the object to be coated, and air pressure alternating for alternately switching the pressure of the shaping air blown from the air blowing passage 70 between high pressure and low pressure And a switching means 60.

The rotary atomizer 12 includes a rotary bell 18, a hollow rotary shaft member 20 that supports and rotates the rotary bell 18.
A paint supply pipe 22 arranged in the rotary shaft member 20 for supplying a liquid paint into the rotary bell 18, and the rotary bell 18 is passed through the rotary shaft member 20 at high speed.
Liquid paint is supplied into the rotary bell 18 from above by the paint supply pipe 22 while rotating about a central axis extending in the longitudinal direction of 20 (vertical direction in the figure), and the liquid paint is centrifugally rotated by the rotary bell 18 It is pressed against the inner peripheral surface to form a thin film, and the thin film liquid paint is also sheared by the centrifugal force from the tip (lower end in the figure) of the rotary bell 18 to be atomized and discharged as an atomized paint toward the outside in the radial direction. .

The air outlet passage 70 is an air outlet ring.
It is provided in 14. The air blowing ring 14 is disposed on the outer peripheral side of the rotary atomizer 12 around the rotation center axis of the rotary atomizer 12, and the rotation center axis of the rotary atomizer 12 is provided inside. An annular air outlet passage 70 is formed around the center. The air outlet passage 70 has an air outlet 70c for blowing shaping air at its tip (lower end in the figure). The air outlet 70c has an annular shape, and is located on the outer peripheral side of the rotary bell 18 slightly behind (upper in the figure) the tip of the rotary bell 18 and close to the tip.

The air blowing passage 70 has an air reservoir 70a in the upstream portion and an inclined air blowing portion in the downstream portion, leaving a predetermined communication gap 70d at a substantially intermediate position in the vertical direction.
It is divided into 70b. The shaping air passes through the air blowing portion 70b so that the air blowing portion 70b
Is blown toward the inside of the rotary bell 18 along the inclination direction of.

Further, the air blowing passage 70 is divided into four passage sections having the same size in the circumferential direction at the position of the one-dot chain line L in FIG. 2 across the upstream air reservoir 70a and the downstream air blowing portion 70b. A, B, C and D are sectioned. Then, in the upstream air reservoir 70a, the passage sections A, B, C, and D are separated by the one-dot chain line L.
Is partitioned by the partition wall 72 provided at the position, and the passage sections A, B, C, and D in the downstream air blowing portion 70b are communicated in the circumferential direction without being partitioned by the partition wall.
It is configured as one common annular passage part.

Two air supply openings 74 are formed on the upper surface of each of the four passage sections A, B, C and D of the air reservoir 70a, and the air supply openings of each passage section are formed.
Each of the air supply sources 74 is connected to a separate air supply source 58, and each air supply source 58 is configured to individually control the air pressure supplied by an air pressure control means 60 as an air pressure alternating switching means having a CPU and a RAM. There is.

In the coating apparatus 10, as described above, four passage sections A, B, C, D are sectioned in the air blowing passage 70 in the circumferential direction, and each passage section A, B, C, D is respectively set. The air is supplied separately and the air pressure can be controlled separately. Therefore, different air pressures can be supplied from the air blowing passage 70 to the passage sections A, B, C and D as required. Shaping air can be blown out.

[Shaping Air Pressure Control] In the coating apparatus 10, pressure switching control of the shaping air blown from the air blowing passage 70 is performed. In this embodiment, the alternate switching control of the air pressure is performed by each passage section A,
The same pressure is switched for B, C, and D at the same timing. That is, the same alternate switching control is performed in the entire area of the air blowing passage 70 in the circumferential direction.

An example of such alternate switching control is shown in FIG.
Will be described with reference to. As shown, in this embodiment, the high pressure is 4 (Kgf / cm ² ) and the low pressure is 0 (Kgf / cm ² ).
The high pressure and the low pressure were alternately switched and repeated, and the repeating cycle was set to 20 (times / sec).

As described above, by alternately switching the pressure of the shaping air blown out from the air blowing passage between the high pressure and the low pressure, it is possible to adjust the bounce and the outer mist in a well-balanced manner and suppress both of them. ,
The coating efficiency can be improved. In other words, by alternately switching between high pressure and low pressure, the outer mist seems to increase at low pressure, but since it can be switched in an extremely short cycle, it quickly changes from low pressure to high pressure, and this high pressure suppresses the increase in outer mist. However, if the pressure remains high, the flow velocity of the shaping air increases and the rebound increases.However, even if the flow velocity increases at high pressure by switching between high pressure and low pressure, the flow velocity immediately decreases due to low pressure. Overall, the increase in flow velocity is sufficiently suppressed and the increase in rebound is also suppressed, so that both outer mist and rebound can be reduced in a well-balanced manner, and coating efficiency can be improved.

Further, as in the case where the paint is a paint for metallic coating, a luster material (aluminum, glass flakes, etc.)
When a mixed material such as an interference color material (mica, etc.) is mixed, the weight of the mixed material is changed according to the switching between the high pressure and the low pressure by alternately switching the air pressure between high pressure and low pressure. The degree of spread changes repeatedly according to the above, whereby the stirring effect of the mixed material is obtained, and the mixed materials of different types and sizes are stirred and uniformly attached on the object to be coated,
Color unevenness can also be reduced.

Regarding the color unevenness, the above coating apparatus 10
In the case where the shaping air pressure is alternately switched under the above conditions, the shaping air pressure is set to 2 (Kgf / c).
Comparison was made by actually coating the object to be coated with the case where it was kept constant at m ² ). The coating conditions other than the shaping air pressure are as follows. An electrostatic type was used as the coating device 10.

Paint: Metallic base (acrylic miramine resin) Interval between coating device and object to be coated: 30 cm Moving speed of coating device: 30 cm / s Rotating bell rotation speed: 20000 rpm Paint discharge rate: 200 cc / min Applied voltage: 50 KV Above When the paint was applied under the conditions and the color unevenness was visually evaluated, the air pressure was changed between when the air pressure was alternately switched and controlled and when the air pressure was kept constant at 2 (Kgf / cm ² ). Two
The one with a constant value (Kgf / cm ² ) has a large color unevenness, while the one with the alternate switching control of the air pressure clearly has less color unevenness and has a sufficient effect on the color unevenness. It was confirmed that there is.

[Coating device having multiple air outlet passages]
Next, a coating apparatus having multiple air outlet passages according to another embodiment of the present invention will be described with reference to FIGS. 5 is a sectional view (a sectional view taken along line VV of FIG. 6),
6 is a sectional view taken along line VI-VI of FIG. 5 (the rotary atomizer is omitted).

The illustrated coating apparatus 10 is provided with double air blowing passages 30 and 32, and has a rotary atomizer 12 for discharging atomized paint radially outward and the rotary atomizer. Bowl 12
Air blowing passages 30 and 32 for blowing shaping air for directing the flow of the atomized paint discharged radially outward from the air to the object to be coated, and shaping blown from the air blowing passages 30 and 32. It is provided with an air pressure alternate switching means 60 for alternately switching the air pressure between high pressure and low pressure.

Since the rotary atomizer 12 is similar to the rotary atomizer of the embodiment shown in FIG. 1, the same components are designated by the same reference numerals and the description thereof will be omitted.

The air outlet passages 30 and 32 are provided in the air outlet ring 14. The air blow-out ring 14 is arranged on the outer peripheral side of the rotary atomizer 12 with the center axis of rotation of the rotary atomizer 12 as a center, and has an annular inner air blow passage 30 and a circular ring inside. And the outer air blowing passage 32 are formed at different positions in the radial direction. Both air outlet passages 30 and 32 are concentrically arranged around the rotation center axis of the rotary atomizer 12, and the outer air outlet passage 32 is located radially outside the inner air outlet passage 30.

The inner air blow-out passage 30 and the outer air blow-out passage 32 are located at substantially intermediate positions in the vertical direction, leaving a predetermined communication gap 30d, 32d therebetween.
It is divided into 30a and 32a and lower air blowout portions 30b and 32b. Both air outlet passages 30 and 32 have air outlets for blowing shaping air at their tips (lower ends in the figure).
It has 30c and 32c. The outer air outlet 32c and the inner air outlet 30c both have an annular shape, and the tip of the rotary bell 18 (lower end in the figure) is located on the outer peripheral side of the rotary bell 18.
It is located slightly rearward (upward in the figure) and close to the tip. The outer air outlet 32c is located radially outward of the inner air outlet 30c, and the inner air outlet portion 30b is inclined toward the inside of the rotary bell 18,
The outer air blowing portion 32b extends in parallel with the central axis of rotation of the rotary bell 18, whereby both air blowing passages 30,
The blowing directions of the shaping air blown out from 32 are different from each other, and are directed forward from the outer air blow passage 32 along the central axis of rotation of the rotary bell 18, and from the inner air blow passage 30 to the inner side of the rotary bell 18. The shaping air will be blown out to the other side.

Further, the inner air blowing passage 30 and the outer air blowing passage 32 are provided with four partition walls 72 extending in the radial direction at predetermined intervals in the circumferential direction. 32 are four passage sections A (30A, 32A), B (30
B, 32B), C (30C, 32C), D (30D, 32D). In addition, this partition wall 72 is used for both air blowing passages 3
Both 0 and 32 are provided only in the upstream air reservoirs 30a and 32a and not in the downstream air outlets 30b and 32b, and the air outlets 30b and 32b are connected to each other in the circumferential direction. It is configured as a common annular passage portion.

Air supply openings 42 are formed on the upper surface of each of the four passage sections A, B, C and D of the air reservoir in both of the air blowing passages 30 and 32, and the air of each passage section is formed. The supply openings 42 are connected to separate air supply sources 58, and each of the air supply sources 58 is configured to be able to separately control the air pressure supplied by the air pressure control means 60, which is an air pressure alternate switching means.

[Pressure Control of Shaping Air] In the above coating apparatus, pressure switching control of the shaping air blown from the air blowing passage is performed. This shaping air pressure alternating switching control is performed by the inner air blowing passage 30
You can do the shaping air blown from
The shaping air blown from the outside air blow passage 32 may be performed, or the shaping air blown from both air blow passages 30 and 32 may be performed. Hereinafter, a specific example of the alternating control of shaping air pressure will be described.

In the first specific example, the pressure of the shaping air blown from the inner air blow passage 30 is constant, and the pressure of the shaping air blown from the outer air blow passage 32 is alternately switched between high pressure and low pressure. Alternate switching control is performed.

According to the first embodiment described above, the inner air blowing passage 30 is inclined so as to blow the shaping air toward the inside of the rotary atomizer 12, so that the inner air blowing passage is formed. Shaping air from 30 more rotating atomizer
The air is blown out toward the inside of 12 to effectively suppress the outer mist, and at that time, the air pressure is reduced to a low pressure to prevent rebound, and in this way, the shaping which is blown out from the outer air blowing passage 32 is performed. By mainly directing the atomized paint to the object to be coated by air, and in that case, by switching the pressure of the shaping air blown from the outside air blowing passage 32 between high pressure and low pressure,
As described above, it is possible to sufficiently increase the direction of the atomized paint while suppressing the increase in the flow velocity and preventing the rebound. Also,
Since the pressure of the shaping air blown out from the inner air blowing passage 30 is made substantially constant, the pressure of the shaping air blown out from the inner air blowing passage 30 is also higher than that in the case where the shaping air is switched to a high pressure and a low pressure. Mist can be suppressed further.

In the second specific example, the pressure of the shaping air blown from the outer air blowing passage 32 is constant, and the pressure of the shaping air blown from the inner air blowing passage 30 is alternately switched between high pressure and low pressure. Alternate switching control is performed.

According to the second embodiment described above, since the inner air blowing passage 30 is inclined so as to blow the shaping air toward the inside of the rotary atomizer 12, the inner air blowing passage 30 More shaping air from the rotating atomizer 12
The air is blown inward to effectively suppress the outer mist, and at that time the air pressure is alternately switched between high pressure and low pressure to suppress the increase in flow velocity and bounce off as described above. Of the atomized paint to the object to be coated while preventing this, and by blowing the shaping air at a low pressure from the outside air blowing passage 32 after doing so, the inside is prevented while rebounding. The outer mist that has passed the shaping air blown from the air blowing passage 30 is directed toward the object by the shaping air from the outer air blowing passage 32, and the outer mist can be sufficiently suppressed. Further, since the pressure of the shaping air blown out from the outer air blowing passage 32 is set to be substantially constant, the pressure of the shaping air blown out from the outer air blowing passage 32 is also switched to a high pressure and a low pressure as compared with the case where the pressure is changed. The outer mist can be further suppressed.

Further, in the case of using a paint containing a mixed material such as a glittering material or an interference coloring material as described above, color unevenness caused by uneven distribution of the mixed material is blown out from the inner air blowing passage 30. This color unevenness can be reduced even when either the pressure of the shaping air that is generated or the pressure of the shaping air that is blown from the outer air blowing passage 32 is switched alternately between high pressure and low pressure. When the pressure of shaping air blown out from the inner air blowing passage 30 close to the atomizer 12 is alternately switched between high pressure and low pressure, the mixed material can be more effectively stirred, and A further effect of reducing color unevenness can be obtained. Further, in this case, the shaping air blown out from the outer air blowing passage 32 has a substantially constant pressure, whereby the flow velocity can be increased as compared with the case where the high pressure and the low pressure are alternately switched. It can be pressed against the object to be coated with a larger force, and as a result, the orientation of the mixed material is improved and a further effect of reducing color unevenness can be obtained.

In any of the above specific examples, as the alternating control of the shaping air pressure, for example, the high pressure is set to 4 (Kgf / cm ² ) and the low pressure is set to 0 (Kgf / cm ² ) as in the above control. The control for setting the repeating cycle to 20 (times / sec) can be performed at the same timing for each passage segment.
In addition, the constant shaping air pressure blown out from the other passage in that case may be a predetermined low pressure lower than the above-mentioned 4 (Kgf / cm ² ), for example.

Of course, any of the above air blowing passages 3
Even when the air pressure is alternately switched to the shaping air pressures blown out from 0, 32, the control mode may be appropriately set based on various coating conditions and the like, and is limited to the above control mode. Not a thing. Further, when the air blowing passages are multiple, the air pressure control in the other passages when the alternate air pressure switching control is performed in any of the passages may be appropriately determined based on various coating conditions and the like. However, the present invention is not limited to the above embodiment.

[Modification] In the above embodiment, the air blowing passage is provided in a single layer or a double layer, but the air blowing channel may be formed in a triple layer or more. In that case, the alternate switching control for alternately switching the air pressure between the high pressure and the low pressure may be performed on the shaping air blown from any of the air blowing passages.

Further, in the above embodiment, the air blowing passage is divided into a plurality of passage sections in the circumferential direction by providing partition walls, but it goes without saying that such partition walls may be provided if necessary. However, the partition may be omitted. .

[Brief description of drawings]

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

FIG. 2 is a plan view of the device shown in FIG.

FIG. 3 is a sectional view taken along line III-III of FIG.

FIG. 4 is a diagram showing an example of alternate control of air pressure.

FIG. 5 is a sectional view showing another embodiment of the rotary atomizing type coating apparatus according to the present invention.

6 is a sectional view taken along line VI-VI of FIG.

[Explanation of symbols]

 12 Rotary atomizer 30, 32, 70 Air outlet passage 60 Air pressure alternate switching means

Claims (10)

[Claims] 1. A rotary atomizing type coating apparatus comprising a rotary atomizer for atomizing and discharging paint by rotating, and an air blowing passage for blowing shaping air from the outer peripheral side of the rotary atomizer. A rotary atomization type coating device comprising an air pressure alternate switching means for alternately switching the pressure of shaping air blown out from the air blowing passage between high pressure and low pressure. 2. The air blowing passages are multiply arranged at different positions in the radial direction and each comprises a plurality of air blowing passages whose air blowing directions are different from each other. 2. The rotary atomizing type coating apparatus according to claim 1, wherein the pressure of the shaping air blown out from the air blowing passage located radially outside is alternately switched between high pressure and low pressure. 3. The rotary atomizing type coating device according to claim 2, wherein the pressure of the shaping air blown from the air blowing passage located on the inner side in the radial direction is substantially constant. 4. The air blowing passages are multiply arranged at different positions in the radial direction and each comprises a plurality of air blowing passages having different air blowing directions. 2. The rotary atomizing coating device according to claim 1, wherein the pressure of the shaping air blown from the air blowing passage located radially inward is alternately switched between high pressure and low pressure. 5. The rotary atomization type coating apparatus according to claim 4, wherein the pressure of the shaping air blown from the air blowing passage located on the outer side in the radial direction is substantially constant. 6. The rotary atomizing type coating apparatus according to claim 1, wherein the coating material is a coating material mixed with a mixing material such as a bright material and an interference coloring material. 7. A rotary atomizing type coating device comprising a rotary atomizer for atomizing and discharging paint by rotating, and an air blowing passage for blowing shaping air from the outer peripheral side of the rotary atomizer. A coating method for coating an object to be coated, wherein the object to be coated is coated by alternately switching the pressure of the shaping air blown from the air blowing passage between high pressure and low pressure. 8. The air blowing passages, which are multiply arranged at different positions in the radial direction and each have a plurality of air blowing directions different from each other, and are located outside in the radial direction. The coating method according to claim 7, wherein the object to be coated is coated while the pressure of the shaping air blown out from the passage is alternately switched between high pressure and low pressure. 9. The air blowing passages, which are multiply arranged at different positions in the radial direction and have a plurality of air blowing passages each having a different air blowing direction from each other, and the air blowing passages are located inside the radial direction. The coating method according to claim 7, wherein the object to be coated is coated while the pressure of the shaping air blown out from the passage is alternately switched between high pressure and low pressure. 10. The coating method according to claim 7, wherein the coating material is a coating material mixed with a mixing material such as a glitter material and an interference coloring material.