Rotary atomization-type coating device and rotary atomization-type coating method

Abstract

The present invention is provided with: a bell cup (11) having a rotating axis (CL) such that a coating pattern of a coating material sprayed from the bell cup has a truncated cone shape; a first annular slit-shaped air outlet (23) that is provided concentrically with the rotating axis and blows out inner shaping air (Sin) from a rear of the bell cup; and a second annular slit-shaped air outlet (24) that is concentric with the rotating axis and has a larger diameter than the first air outlet and that blows outer shaping air (Sout) from the rear of the bell cup.

Description

Rotary atomizer coating device and rotary atomizer coating method

[0001] The present invention relates to a rotary atomizer coating apparatus and a rotary atomizer coating method.

[0002] In a typical rotary atomizer coating device, when paint is sprayed while shaping air is supplied from the back of a bell cup, a doughnut-shaped coating pattern (also called a spray pattern) with a circular hole in the center is formed. When the coating device including the bell cup is moved relative to the workpiece with this doughnut-shaped coating pattern, the amount of paint applied in the direction perpendicular to the direction of movement, i.e., the coating film thickness distribution, becomes uneven. Therefore, it has been proposed to transform the coating pattern sprayed from the bell cup into an elliptical coating pattern (Patent Document 1).

[0003] Japanese Unexamined Patent Publication No. 60-54754

[0004] However, while transforming the coating pattern into an elliptical one, as in the prior art, eliminates the central circular hole, it reduces the area of ​​the coating pattern. This requires either increasing the number of coats or increasing the paint discharge rate and gun distance. The former creates a new problem of reduced productivity, while the latter creates a new problem of reduced paint atomization. Therefore, to avoid these new problems, it is desirable to change the doughnut-shaped coating pattern to a frustum-shaped coating pattern (one in which the film thickness distribution in the direction perpendicular to the direction of movement is trapezoidal).

[0005] SUMMARY OF THE INVENTION The problem to be solved by the present invention is to provide a rotary atomizer coating apparatus and method that produces a coating pattern in the shape of a truncated cone.

[0006] The present invention solves the above problem by rotating a bell cup around a rotation axis, supplying paint to the paint diffusion surface of the bell cup, and atomizing and applying the paint using the bell cup, by blowing inner shaping air in an annular slit shape from the back surface of the bell cup, concentric with the rotation axis, and simultaneously blowing outer shaping air in an annular slit shape from the back surface of the bell cup, concentric with the rotation axis and at a position with a larger diameter than the inner shaping air.

[0007] According to the present invention, the coating pattern of the paint sprayed from the bell cup is in the shape of a truncated cone.

[0008] FIG. 1 is a cross-sectional view showing one embodiment of a rotary atomizer coating apparatus according to the present invention. FIG. 2 is a cross-sectional view showing another embodiment of a rotary atomizer coating apparatus according to the present invention. FIG. 3 is a diagram showing the state of airflow generated on the front surface of a bell cup (without shaping air). FIG. 4 is a diagram showing the state of airflow generated on the front surface of a bell cup (inner shaping air only). FIG. 5 is a diagram showing the state of airflow generated on the front surface of a bell cup (inner shaping air only, increased flow rate). FIG. 6 is a diagram showing the film thickness distribution when only inner shaping air is supplied. FIG. 7 is a diagram showing the state of airflow generated on the front surface of a bell cup (outer shaping air only). FIG. 8 is a diagram showing the state of airflow generated on the front surface of a bell cup (outer shaping air only, increased flow rate). FIG. 9 is a diagram showing the film thickness distribution when only outer shaping air is supplied. FIG. 10 is a diagram showing the state of airflow generated on the front surface of a bell cup (both inner and outer shaping air). FIG. 11 is a diagram showing the film thickness distribution when both inner and outer shaping air are supplied. 10A and 10B are diagrams showing the film thickness distribution of Comparative Example 1 in which the first air outlet from which the inner shaping air is blown out is configured with a plurality of holes instead of a slit shape, and Comparative Example 2 in which the second air outlet from which the outer shaping air is blown out is configured with a plurality of holes instead of a slit shape.

[0009] First Embodiment An embodiment of the present invention will now be described with reference to the drawings. FIG. 1 is a cross-sectional view showing the tip of a rotary atomizer coating device 1 according to one embodiment of the present invention. The rotary atomizer coating device 1 shown in FIG. 1 has a housing 12 made of an electrically insulating material. A hollow shaft 14 is provided within the housing 12 and is rotatable about a rotation axis CL. The hollow shaft 14 is driven to rotate by an air motor 13, and a bell cup 11 that sprays paint is fixed to the tip of the hollow shaft 14 by means of screw fastening or the like. The bell cup 11 is also referred to as an atomizing head or spray head, but will be referred to as a bell cup in this specification. The bell cup 11 rotates together with the hollow shaft 14 about the rotation axis CL. A non-rotating feed tube 16 is disposed in the center hole of the hollow shaft 14, and supplies paint and cleaning thinner from a paint supply device 15 to the bell cup 11.

[0010] In this embodiment, the rotary atomizer coating device 1 applies paint particles charged by a high-voltage power supply 17 along an electrostatic field formed between the coating device and the workpiece, depositing the paint on the workpiece. The workpiece is located on the left side of FIG. 1 at a predetermined gun distance and is grounded via a conductive member that holds the workpiece, such as a coating cart or coating hanger. As shown in FIG. 1 , the high-voltage application method can be an internal application method, in which the high-voltage power supply 17 is installed within the housing 12 and the voltage is applied to the bell cup 11, also made of a conductive material, via a hollow shaft 14 made of a conductive material. Alternatively, when using a water-based paint, an external application type electrostatic coating device can be used, in which a discharge electrode connected to the high-voltage power supply is installed around the bell cup 11 and the voltage is applied to the paint particles ejected from the bell cup 11.

[0011] The tip of the feed tube 16 is exposed from the tip of the hollow shaft 14 and extends toward the interior of the bell cup 11. Paint or cleaning thinner is supplied to this feed tube 16 from the paint supply device 15 and dispensed from its tip onto the paint diffusion surface 111 of the bell cup 11. The cleaning thinner is a cleaning liquid (organic solvent for organic solvent-based paints, or water for water-based paints) for cleaning the paint diffusion surface 111 of the bell cup 11 and the hub 18 (described later). When the rotary atomizer coating apparatus 1 of this embodiment is applied to a topcoat or undercoat coating process that requires a color change, the cleaning thinner is supplied for cleaning when changing the paint color. Therefore, in a coating process that does not require a color change, such as a undercoat coating process in which only a single type of undercoat paint is applied, only the paint may be supplied to the feed tube 16. The color change is performed by a color change valve unit (not shown) included in the paint supply device 15.

[0012] Bell cup 11 is generally cup-shaped and, in this example, is made of a conductive material such as metal. It has a paint-spreading surface 111 on the inner surface of the cup, a cup-shaped outer surface 112, and a leading edge 113 located at the tip of the inner surface from which paint is released. A hub 18 is attached to the center of the base end of bell cup 11 and to the tip of feed tube 16. This hub 18 can be made of either a conductive material such as metal or an electrically insulating material such as plastic. Hub 18 may be attached to the tip of hollow shaft 14 or the base end of bell cup 11 so as to rotate together with hollow shaft 14 or bell cup 11, or it may be attached to the tip of feed tube 16 so as to be non-rotating. Bell cup 11 may also be made of an electrically insulating material.

[0013] Since the bell cup 11 is circular in front view, the hub 18 is also circular in front view. A plurality of paint discharge holes 19 are formed at predetermined intervals on the outer periphery of the hub 18, and paint or cleaning thinner supplied from the tip of the feed tube 16 passes through the paint discharge holes 19 in the hub 18 and is guided to the paint diffusion surface 111 of the bell cup 11, where it is scattered from the entire circumference of the tip edge 113 by centrifugal force.

[0014] Now, in order to deflect the paint particles atomized by the bell cup 11 in a direction toward the workpiece positioned in front of the bell cup 11, shaping air is supplied from the rear side of the bell cup 11. In the rotary atomizer coating device 1 of this embodiment, inner shaping air S is supplied from the rear side of the bell cup 11, which is concentric with the rotation axis CL. ｉｎ is blown out in the shape of an annular slit, and at the same time, the inner shaping air S ｉｎ Outer shaping air S with a larger diameter and concentric with the rotation axis CL ｏｕｔ is blown out in an annular slit shape.

[0015] For this reason, an air ring 20 is provided at the tip of the housing 12 so as to be concentric with the rotation axis CL and surround the bell cup 11. The air ring 20 is formed by assembling an outer ring 21 and an inner ring 22 made of a conductive or electrically insulating material, and the tip where the outer ring 21 and inner ring 22 are assembled forms an annular slit-shaped second air outlet 24. Furthermore, an annular second semi-closed space 26 is formed inside the assembled outer ring 21 and inner ring 22, and a plurality of through holes 27 are formed at predetermined intervals on the base end side of the second semi-closed space 26. When air is supplied from the second air supply device 30 to these through holes 27, outer shaping air S flows out from the annular slit-shaped second air outlet 24 formed at the tip of the air ring 20. ｏｕｔ is burst out.

[0016] On the other hand, by providing the air ring 20 in this example with a small gap between the inner ring 22 of the air ring 20 and the bell cup 11, an annular slit-shaped gap is formed between the tip of the inner ring 22 and the tip edge 113 of the bell cup 11. In this embodiment, this annular slit-shaped gap is formed by the inner shaping air S. ｉｎFurthermore, a first semi-closed space 25 is formed between the inner peripheral surface of the inner ring 22, the outer surface 112 of the bell cup 11, and the housing 12, and a plurality of through holes 28 are formed at predetermined intervals on the base end side of the first semi-closed space 25. When air is supplied to these through holes 28 from a first air supply device 29, inner shaping air S is blown out from the first air outlet 23 in the form of an annular slit formed between the inner ring 22 of the air ring 20 and the bell cup 11. ｉｎ is burst out.

[0017] The inner shaping air S blown out from these first air outlets 23 ｉｎ and outer shaping air S blown out from the second air outlet 24. ｏｕｔ By appropriately adjusting the flow rate of the shaping air and the shaping air, it is possible to control the flight direction of the paint particles projecting tangentially from the tip of the bell cup 11, i.e., the paint pattern. In addition to the force due to the electrostatic field described above, the paint particles are also given momentum by these shaping airs.

[0018] Now, referring to FIGS. 3 to 7B, the inner shaping air S ｉｎ and Outer Shaping Air S ｏｕｔ The effect of is explained based on experimental data.

[0019] 3 shows the state of the airflow generated in front of the bell cup 11 when no shaping air is supplied. In this case, as the bell cup 11 rotates at high speed, the air on the surface of the bell cup 11 is dragged, generating an airflow F1 that flows radially outward. Furthermore, because of the generation of airflow F1, air in front of the bell cup 11 is drawn toward the bell cup 11, generating an airflow F2.

[0020] FIG. 4A is a diagram showing the state of the airflow occurring in front of the bell cup 11, and the inner shaping air S ｉｎ 4B shows the case where only the inner shaping air S is supplied. ｉｎ As shown in FIG. 4A, the air flow rate is increased when only the inner shaping air S is supplied from the rear surface of the bell cup 11.ｉｎ When the air is blown out, the airflow (F1 in FIG. 3) flows radially outward from the bell cup 11 and the inner shaping air S ｉｎ The inner shaping air S ｉｎ After colliding with the surface of the workpiece P, the air becomes excess airflow F4 and diffuses to the surroundings. In this case, the cross section of the coating film C has a two-humped camel shape with a concave center.

[0021] From the state of FIG. 4A, the inner shaping air S ｉｎ When the flow rate of the inner shaping air S is increased, the circulating air flow F3 becomes larger, and the paint particles tend to gather slightly in the center, as shown in Figure 4B. In this case, the cross section of the coating film C remains in the shape of a two-humped camel with a concave center, but the distance between the two raised portions becomes slightly narrower. ｉｎ Since the air is blown out along the back surface of the bell cup 11, an outward velocity component is inevitably generated. Therefore, even if the flow rate is increased, there is little effect in improving the distribution of the two-humped camel shape, but the effect of increasing the circulating airflow F3 in front of the bell cup 11 is that it has the effect of concentrating the entire pattern in the center.

[0022] FIG. 4C shows the inner shaping air S as shown in FIGS. 4A and 4B. ｉｎ The horizontal axis indicates the position on the surface of the workpiece P, and the vertical axis indicates the thickness of the coating film C. ｉｎ When only air is supplied, the film thickness distribution takes on a two-humped camel shape with a concave center, as shown in Figure 4C. Increasing the air flow rate causes the paint particles to gather in the center, but the two-humped camel shape remains. The width of the coating pattern is approximately 550 to 600 mm, and little change in the width of the coating pattern due to changes in the air flow rate is observed.

[0023] FIG. 5A is a diagram showing the state of the airflow occurring in front of the bell cup 11, and the outer shaping air S ｏｕｔ 5B shows the case where only the outer shaping air S is supplied. ｏｕｔAs shown in FIG. 5A, the air flow rate is increased when only the outer shaping air S is supplied from the rear surface of the bell cup 11. ｏｕｔ When the outer shaping air S is blown out, ｏｕｔ Inner Shaping Air S ｉｎ Since the air is blown out from the outside of the first air outlet 23 at an angle that targets the bell edge of the bell cup 11, a velocity component is generated that is directed toward the central axis of the bell cup 11. ｏｕｔ The outer shaping air S and the air flow (F1 in FIG. 3) directed radially outward from the bell cup 11 join together, generating a circulating air flow F5 between the bell cup 11 and the surface of the workpiece P. ｏｕｔ After colliding with the surface of the workpiece P, the airflow F4 diffuses to the surrounding area. In this case, the cross section of the coating film C has a two-humped camel shape with a concave center, but the spacing between the raised portions is slightly smaller than that of the cross section shown in Figure 4A.

[0024] From the state of FIG. 5A, the outer shaping air S ｏｕｔ When the flow rate of the outer shaping air S is increased, the velocity component toward the central axis of the bell cup 11 increases, and the apex of the two-humped camel shape is extremely concentrated in the center, as shown in FIG. ｏｕｔ has an extreme effect of gathering the vertices of the two-humped camel shape to the center, so that the cross section of the coating film C has a sharp distribution that is nearly triangular, as shown in FIG. 5B.

[0025] FIG. 5C shows the outer shaping air S as shown in FIGS. 5A and 5B. ｏｕｔ The horizontal axis indicates the position on the surface of the workpiece P, and the vertical axis indicates the thickness of the coating film C. ｏｕｔ As shown in Figure 5C, when only air is supplied, the film thickness distribution takes on a two-humped camel shape with a concave center, and while increasing the air flow rate causes the paint droplets to gather in the center, the two-humped camel shape remains. Furthermore, the width of the coating pattern is approximately 550 to 600 mm, and it can be seen that while fluctuations in air flow rate cause large fluctuations in film thickness in the center, the width of the coating pattern is not significantly affected.

[0026] FIG. 6A is a diagram showing the state of the airflow occurring in front of the bell cup 11, and the inner shaping air S ｉｎ and Outer Shaping Air S ｏｕｔ As shown in FIG. 5A, the inner shaping air S is supplied from the rear surface of the bell cup 11. ｉｎ and Outer Shaping Air S ｏｕｔ are blown out at the same time, the airflow (F1 in FIG. 3) directed radially outward from the bell cup 11 and the inner shaping air S ｉｎ and outer shaping air S ｏｕｔ The air flows merge together, generating a circulating air flow F6 between the bell cup 11 and the surface of the workpiece P. This circulating air flow F6 causes the inner shaping air S shown in FIG. ｉｎ The entire pattern is gathered in the center by the circulating air flow F3 by the outer shaping air S shown in FIG. ｏｕｔ The circulating air flow F5 by the outer shaping air S allows the top of the two-humped camel to be gathered in the center. Therefore, the paint particles are gathered in the center appropriately while maintaining the pattern width. ｏｕｔ After colliding with the surface of the workpiece P, the air becomes excess airflow F4 and diffuses to the surroundings. In this case, the cross section of the coating film C is trapezoidal with the central depression eliminated.

[0027] FIG. 6B shows the inner shaping air S ｉｎ and Outer Shaping Air S ｏｕｔ When both inner shaping air S are supplied ｉｎ The flow rate is 145NL / min, and the outer shaping air S ｏｕｔ The horizontal axis indicates the position on the surface of the object P to be coated, and the vertical axis indicates the thickness of the coating film C. ｉｎ and Outer Shaping Air S ｏｕｔ 6B, the coating thickness distribution when both of the above are supplied is approximately 400 mm wide, and the coating thickness distribution of the coating pattern rises sharply toward the center, forming the side of a truncated cone. The coating thickness in the central part of the coating pattern is almost flat, and the width of the flat part expands to approximately 250 mm.

[0028] As described above, in the rotary atomizer coating device 1 of this embodiment, the inner shaping air S is blown from the back surface of the bell cup 11. ｉｎ is blown out in a circular slit shape, and at the same time, the outer shaping air S ｏｕｔ By blowing the paint in an annular slit shape, a coating pattern having a truncated cone shape can be obtained, and the film thickness distribution in the direction perpendicular to the moving direction becomes trapezoidal.

[0029] In the rotary atomizer coating device 1 of this embodiment, although not particularly limited, the outer shaping air S ｏｕｔ The flow rate of the inner shaping air S ｉｎ By setting the flow rate distribution in this manner, the inner shaping air S ｉｎ The mixed gas of the atomized paint particles and the outer shaping air S ｏｕｔ The shielding is performed so that the air fills the front of the bell cup 11, and a coating pattern can be formed in which the periphery of the truncated cone is steep and the center is flat, resulting in a film thickness distribution.

[0030] In addition, in the rotary atomizer coating device 1 of this embodiment, although not particularly limited, the outer shaping air S ｏｕｔ The flow rate of the inner shaping air S ｉｎ By distributing the flow rates in this manner, it is possible to obtain a coating pattern having a film thickness distribution with steep tails and a flat center.

[0031] In the rotary atomizer coating device 1 of this embodiment, although not particularly limited, the ratio of the opening cross-sectional area of ​​the annular slit-shaped first air outlet 23 to the opening cross-sectional area of ​​the annular slit-shaped second air outlet 24 is preferably 3:1 to 4:1. By allocating the opening cross-sectional areas in this manner, a coating pattern can be achieved in which the film thickness distribution is steep at both ends and flat in the center.

[0032] In the rotary atomizer coating device 1 of this embodiment, although not particularly limited, it is preferable that the distance between the tip of the inner peripheral surface of the air ring 20 and the tip of the bell cup 11 does not exceed 2 mm.

[0033] In the rotary atomizer coating device 1 of this embodiment, although not particularly limited, the inner shaping air S ｉｎ is preferably non-directional with respect to the circumferential direction of the first air outlet 23. The fact that the inner shaping air S is non-directional with respect to the circumferential direction of the first air outlet 23 means that the inner shaping air S ｉｎ This means that the blowing direction of the air is not inclined in the circumferential direction, but is blown along the direction of the rotation axis CL of the bell cup 11.

[0034] FIG. 7A shows the inner shaping air S ｉｎ 7A shows the film thickness distribution of Comparative Example 1 in which the first air outlet 23 from which the outer shaping air S is blown out is configured with a plurality of holes instead of a slit shape, and FIG. 7B shows the film thickness distribution of Comparative Example 1 in which the first air outlet 23 from which the outer shaping air S is blown out is configured with a plurality of holes instead of a slit shape. ｏｕｔ 6B shows the coating thickness distribution of Comparative Example 2, in which the second air outlet 24 from which the shaping air is blown out is configured with a plurality of holes instead of a slit. In both Comparative Examples 1 and 2, the coating thickness distribution is not symmetrical about the center of the bell cup 11. This is because the holes in Comparative Examples 1 and 2 are formed at an angle in the circumferential direction, and the shaping air blown out from these holes has directionality in the circumferential direction. In contrast, in the rotary atomizer coating apparatus 1 of this embodiment, the coating thickness distribution is symmetrical about the center of the bell cup 11, as shown in FIG.

[0035] Second Embodiment Figure 2 is a cross-sectional view showing another embodiment of the rotary atomizer coating apparatus according to the present invention. The rotary atomizer coating apparatus 1 according to the embodiment shown in Figure 2 is different from the rotary atomizer coating apparatus 1 according to the embodiment shown in Figure 1 in that the configuration of the air ring 20 is partially different. The other components are the same as those of the rotary atomizer coating apparatus 1 according to the embodiment shown in Figure 1, and therefore the same components are designated by the same reference numerals and the description thereof will be incorporated herein.

[0036] 1 , the air ring 20 of this embodiment is provided at the tip of the housing 12, concentric with the rotation axis CL, and surrounding the bell cup 11. The air ring 20 of this embodiment also comprises an outer ring 21 and an inner ring 22, each made of a conductive or electrically insulating material, assembled together, and the tip where the outer ring 21 and inner ring 22 are assembled forms an annular slit-shaped second air outlet 24. Furthermore, an annular second semi-closed space 26 is formed within the assembled outer ring 21 and inner ring 22, and a plurality of through holes 27 are formed at predetermined intervals on the base end side of the second semi-closed space 26.

[0037] 1 , the air ring 20 of this embodiment has a partition wall 31 that circumferentially divides the second semi-closed space 26 and is provided integrally with the inner ring 22. This circumferentially extending partition wall 31 has a plurality of through holes 32 formed discretely, and an elastic seal member 33 is interposed between the partition wall 31 and the outer ring 21. The sum of the cross-sectional areas of the plurality of through holes 32 is set to be larger than the cross-sectional area of ​​the opening at the tip of the second air outlet 24. When air is supplied from the second air supply device 30 to the through holes 27, the air is rectified by the plurality of through holes 32 formed in the partition wall 31 and then reaches the annular slit-shaped second air outlet 24 formed at the tip of the air ring 20, and is emitted from the second air outlet 24 as outer shaping air S. ｏｕｔ is burst out.

[0038] 1, the air ring 20 of this embodiment is different from the air ring 20 of the embodiment shown in FIG. 1 in that the tip of the outer ring 21 is set back from the tip of the inner ring 22, as shown in FIG. 2. With this configuration, the outer shaping air S ｏｕｔ Although the flow rate of the outer shaping air S increases slightly, ｏｕｔ The coating pattern distribution is less responsive to fluctuations in the flow rate, resulting in a stable coating pattern. In addition, since the tip of the outer ring 21 is set back from the tip of the inner ring 22, even if the second air outlet 24 is blocked by paint mist, it can be easily detected visually.

[0039] As described above, the rotary atomizer coating device 1 of this embodiment includes the bell cup 11 having the rotation axis CL, and the inner shaping air S, which is provided concentrically with the rotation axis CL and is blown from the back surface of the bell cup 11. ｉｎ and a first air outlet 23 having an annular slit shape that blows out outer shaping air S from the rear surface of the bell cup 11. The first air outlet 23 is concentric with the rotation axis CL and has a larger diameter than the first air outlet 23. ｏｕｔ The air blower has a second air outlet 24 in the form of an annular slit, which blows out air from the nozzle. This allows for a coating pattern with a truncated cone shape, with steep peripheral sides and a flat center. As a result, a coating film with a uniform thickness distribution can be obtained even with a small number of recoats. In addition, the coating speed can be reduced to, for example, 600 mm / sec or less, improving the coating efficiency.

[0040] In addition, according to the rotary atomizer coating device 1 of this embodiment, the inner shaping air S ｉｎ Since the first air outlet 23 is non-directional with respect to the circumferential direction, the flat portion in the center of the coating pattern, which is shaped like a truncated cone, can be made symmetrical.

[0041] In addition, according to the rotary atomizer coating device 1 of this embodiment, the outer shaping air S ｏｕｔ The flow rate of the inner shaping air S ｉｎ Since the flow rate is greater than or equal to the flow rate of the inner shaping air S ｉｎ The mixed gas of the atomized paint particles and the outer shaping air S ｏｕｔ The shield is formed so that the coating fills the front of the bell cup 11. This allows for a coating pattern with a film thickness distribution in which the sides around the frustum of the cone are steep and the center is flat.

[0042] Furthermore, according to the rotary atomization coating device 1 of this embodiment, the ratio of the opening cross-sectional area of ​​the first air outlet 23 to the opening cross-sectional area of ​​the second air outlet 24 is 3:1 to 4:1, so that a coating pattern having a truncated cone shape with steep peripheral sides and a flat center can be produced.

[0043] Furthermore, the rotary atomizer coating device 1 of this embodiment further includes an air ring 20 that is concentric with the rotation axis CL and that surrounds the bell cup 11, and that has a second air outlet 24 formed at its tip. The annular slit-shaped gap between the tip of the inner peripheral surface of the air ring 20 and the tip of the bell cup 11 serves as a first air outlet 23, and inner shaping air S is blown into a first semi-closed space 25 between the inner peripheral surface of the air ring 20 and the back surface of the bell cup 11. ｉｎ Since the original air is supplied, the first air outlet 23 can be configured with a simple structure. ｉｎ The airflow induced by the bell cup 11 can suppress the accumulation of paint mist on the outer surface of the bell cup 11.

[0044] Furthermore, according to the rotary atomizer coating device 1 of this embodiment, the distance between the tip of the inner surface of the air ring 20 and the tip of the bell cup 11 does not exceed 2 mm, so the first air outlet 23 can be constructed with a simple structure.

[0045] In addition, according to the rotary atomizer coating device 1 of this embodiment, the air ring 20 includes an outer shaping air S ｏｕｔ The air ring 20 has a second semi-closed space 26 to which the original air is supplied, a partition wall 31 that divides the second semi-closed space 26 in the circumferential direction, and a plurality of through holes 32 formed in the partition wall 31, and since the sum of the cross-sectional areas of the through holes 32 is larger than the opening cross-sectional area of ​​the tip of the second air blowing outlet 24, when air is supplied from the second air supply device 30 to the through holes 27, the air is rectified by the plurality of through holes 32 formed in the partition wall 31. Then, this rectified air reaches the second air blowing outlet 24 in the shape of an annular slit formed at the tip of the air ring 20, and is emitted from the second air blowing outlet 24 as outer shaping air S. ｏｕｔ That is, by providing the partition wall 31 with a plurality of through holes 32, it is possible to ensure uniform spacing between the annular slit-shaped second air outlets 24. Furthermore, by providing a plurality of through holes 32, it is possible to equalize the flow rate of air supplied to the second air outlets 24.

[0046] Furthermore, according to the rotary atomizer coating device 1 of this embodiment, the air ring 20 is formed by assembling the outer ring 21 and the inner ring 22, the partition wall 31 is formed integrally with the inner ring 22, and an elastic seal member 33 is interposed between the partition wall 31 and the outer ring 21, so that axial misalignment can be suppressed when assembling the outer ring 21 and the inner ring 22. Furthermore, since the partition wall 31 extends in the circumferential direction, the rigidity of the opening of the second air outlet 24 is increased, and the outer shaping air S ｏｕｔ The deformation of the elastic seal member 33 can absorb vibrations that occur due to the flow rate.

[0047] In addition, according to the rotary atomizer coating device 1 of this embodiment, the tip of the outer ring 21 is set at a position retracted from the tip of the inner ring 22, so that the outer shaping air S ｏｕｔ Although the flow rate of the outer shaping air S increases slightly, ｏｕｔ The coating pattern distribution is less responsive to fluctuations in the flow rate, resulting in a stable coating pattern. In addition, since the tip of the outer ring 21 is set back from the tip of the inner ring 22, even if the second air outlet 24 is blocked by paint mist, it can be easily detected visually.

[0048] DESCRIPTION OF SYMBOLS 1...Rotary atomizer coating device 11...Bell cup CL...Rotating shaft 111...Paint diffusion surface 112...Outer surface 113...Tip edge 12...Housing 13...Air motor 14...Hollow shaft 15...Paint supply device 16...Feed tube 17...High voltage power supply 18...Hub 19...Paint discharge hole 20...Air ring 21...Outer ring 22...Inner ring 23...First air outlet 24...Second air outlet 25...First semi-closed space 26...Second semi-closed space 27, 28...Through holes 29...First air supply device 30...Second air supply device 31...Partition wall 32...Through holes 33...Elastic seal member

Claims

1. (delete)

2. (delete)

3. (delete)

4. (delete)

5. (delete)

6. (delete)

7. (delete)

8. (delete)

9. (delete)

10. (delete)

11. a bell cup having a rotation axis; a first air outlet having an annular slit shape that is provided concentrically with the rotation shaft and that blows inner shaping air from a rear surface of the bell cup; a second air outlet having an annular slit shape, which is concentric with the rotation shaft and has a larger diameter than the first air outlet, and which blows out outer shaping air from a back surface of the bell cup, A rotary atomization coating device, wherein the ratio of the opening cross-sectional area of ​​the first air outlet to the opening cross-sectional area of ​​the second air outlet is 3:1 to 4:

1.

12. an air ring that is concentric with the rotation shaft and surrounds the bell cup, and has the second air outlet formed at a tip thereof; an annular slit-shaped gap between the tip of the inner circumferential surface of the air ring and the tip of the bell cup serves as the first air outlet, 12. The rotary atomizer coating apparatus according to claim 11, wherein original air that becomes the inner shaping air is supplied to a semi-closed space between the inner peripheral surface of the air ring and the back surface of the bell cup.

13. a bell cup having a rotation axis; a first air outlet having an annular slit shape that is provided concentrically with the rotation shaft and that blows inner shaping air from a rear surface of the bell cup; a second air outlet having an annular slit shape, which is concentric with the rotation shaft and has a larger diameter than the first air outlet, and which blows out outer shaping air from the back surface of the bell cup; an air ring that is concentric with the rotation shaft and surrounds the bell cup, and has the second air outlet formed at a tip thereof; an annular slit-shaped gap between the tip of the inner circumferential surface of the air ring and the tip of the bell cup serves as the first air outlet, A rotary atomization type coating device in which original air that becomes the inner shaping air is supplied to a semi-closed space between the inner peripheral surface of the air ring and the back surface of the bell cup.

14. 14. The rotary atomizer coating device according to claim 13, wherein the ratio of the cross-sectional area of ​​the opening of said first air outlet to the cross-sectional area of ​​the opening of said second air outlet is 3:1 to 4:

1.

15. 15. The rotary atomizer coating apparatus according to claim 13, wherein the flow rate of the outer shaping air is equal to or greater than the flow rate of the inner shaping air.

16. a bell cup having a rotation axis; a first air outlet having an annular slit shape that is provided concentrically with the rotation shaft and that blows inner shaping air from a rear surface of the bell cup; a second air outlet having an annular slit shape, which is concentric with the rotation shaft and has a larger diameter than the first air outlet, and which blows out outer shaping air from a back surface of the bell cup, the inner shaping air has a velocity component directed outward relative to the axis of rotation; the outer shaping air has a velocity component directed inward relative to the axis of rotation; A rotary atomizer coating device, wherein the flow rate of the outer shaping air is equal to or greater than the flow rate of the inner shaping air.

17. 17. The rotary atomizer coating device according to claim 11, wherein the inner shaping air is non-directional with respect to the circumferential direction of the first air outlet.

18. 14. The rotary atomizer coating apparatus according to claim 12, wherein the distance between the tip of the inner peripheral surface of the air ring and the tip of the bell cup does not exceed 2 mm.

19. The air ring is A semi-closed space to which source air that becomes the outer shaping air is supplied; A partition wall that divides the semi-closed space in a circumferential direction; a plurality of through holes provided in the partition wall; 19. A rotary atomizer coating device according to claim 12, 13 or 18, wherein the sum of the cross-sectional areas of the through holes is larger than the cross-sectional area of ​​the opening at the tip of the second air outlet.

20. The air ring is formed by assembling an outer ring and an inner ring, the partition wall is integrally formed with the inner ring; 20. The rotary atomizer coating apparatus according to claim 19, wherein an elastic seal member is interposed between said partition wall and said outer ring.

21. 21. The rotary atomizer coating apparatus according to claim 20, wherein the tip of the outer ring is set back from the tip of the inner ring.

22. A rotary atomization coating method in which a bell cup is rotated around a rotation axis, paint is supplied to a paint diffusion surface of the bell cup, and the paint is atomized by the bell cup for coating, Inner shaping air is blown out in an annular slit shape from the back surface of the bell cup, which is concentric with the rotation axis, and an outer shaping air is blown out in an annular slit shape from a rear surface of the bell cup at a position concentric with the rotation axis and having a larger diameter than the inner shaping air; A rotary atomization coating method, wherein the ratio of the opening cross-sectional area of ​​the first air outlet for blowing out the inner shaping air to the opening cross-sectional area of ​​the second air outlet for blowing out the outer shaping air is 3:1 to 4:

1.

23. A rotary atomization coating method in which a bell cup is rotated around a rotation axis, paint is supplied to a paint diffusion surface of the bell cup, and the paint is atomized by the bell cup for coating, Inner shaping air is blown out in an annular slit shape from the back surface of the bell cup, which is concentric with the rotation axis, and an outer shaping air is blown out in an annular slit shape from a rear surface of the bell cup at a position concentric with the rotation axis and having a larger diameter than the inner shaping air; an air ring provided concentrically with the rotation shaft and surrounding the bell cup, the air ring having a second air outlet formed at a tip thereof for blowing out the outer shaping air; an annular slit-shaped gap between the tip of the inner circumferential surface of the air ring and the tip of the bell cup serves as a first air outlet for blowing out the inner shaping air, A rotary atomization coating method in which original air that becomes the inner shaping air is supplied to a semi-closed space between the inner peripheral surface of the air ring and the back surface of the bell cup.

24. A rotary atomization coating method in which a bell cup is rotated around a rotation axis, paint is supplied to a paint diffusion surface of the bell cup, and the paint is atomized by the bell cup for coating, Inner shaping air is blown out in an annular slit shape from the back surface of the bell cup, which is concentric with the rotation axis, and an outer shaping air is blown out in an annular slit shape from a rear surface of the bell cup at a position concentric with the rotation axis and having a larger diameter than the inner shaping air; the inner shaping air has a velocity component directed outward relative to the axis of rotation; the outer shaping air has a velocity component directed inward relative to the axis of rotation; A rotary atomization coating method, wherein the flow rate of the outer shaping air is equal to or greater than the flow rate of the inner shaping air.