JP3838042B2 - Rotary atomizing coating equipment - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a rotary atomizing coating apparatus, and more particularly, to an improvement in a seal portion provided on an atomizing head with a predetermined gap between a non-rotating paint supply pipe.
[0002]
[Prior art]
In order to coat an object to be coated, such as an automobile body, a rotary atomizing type coating apparatus is widely used as disclosed in JP-A-7-328493. The rotary atomizing coating apparatus has a cup-shaped atomizing head, also called a bell. A center feed tube type rotary atomizing coating device is a feed tube in which an atomizing head is provided at the tip side of a hollow rotating shaft, and paint is supplied to the atomizing head on the center of rotation in the center hole of the rotating shaft. Are arranged in a non-rotating state. Then, by rotating the atomizing head at a high speed and supplying the coating material to the inner surface side of the atomizing head through the feed tube, the supplied coating material is atomized and sprayed by the centrifugal force accompanying the rotation.
[0003]
In order to prevent the paint supplied from the feed tube from flowing back to the rotating shaft side, the atomizing head is provided with a seal portion with a predetermined gap between the atomizing head and the feed tube exposed from the tip of the rotating shaft. ing. The inner end of the seal portion closest to the outer peripheral surface of the feed tube is formed in parallel with the axial direction of the feed tube.
[0004]
In the conventional seal portion, the gap is set as narrow as possible within a range that does not hinder the smooth rotation of the atomizing head, and the axial length of the inner end is as long as possible (about 3 mm). It is customary to set to.
[0005]
[Problems to be solved by the invention]
Since the inner end of the seal part forms a cylindrical inner wall coaxial with the rotation axis, when paint enters the gap between the seal part and the feed tube, the paint is caused by the rotating atomizing head. It is centrifuged and only solid content such as pigment in the paint is deposited on the inner end surface of the seal portion. The deposited solid content gradually grows by continuing the operation of the coating apparatus, and finally becomes a lump and peels off from the seal portion. When this solid content lump adheres to the painted surface, a pigment lump referred to as “butsu” is generated on the painted surface, which may reduce the quality of the coating film. Further, when the solid lump that has been peeled off blocks the coating passage of the atomizing head, the sprayed state of the coating becomes non-uniform, and there is a concern that the quality of the coating film may be lowered.
[0006]
Seal air is supplied to the gap between the seal portion and the feed tube. The pressure and flow rate of the seal air are such that the gap is prevented from becoming negative pressure and the paint is not sucked. It is set and does not have the effect of blowing away the paint that has entered the gap.
[0007]
As a result of earnest research to solve the problems associated with the above-described conventional technology, the inventor has a conventional fixed idea that it is necessary to set the axial length of the inner end portion of the seal portion as long as possible. By defeating and defining the axial length of the inner end to a predetermined dimension, or defining the shape of the inner end to a predetermined shape, it is possible to effectively prevent the paint from adhering to the seal portion and staying there. The inventors have found that this can be prevented, and have completed the present invention.
[0008]
Then, an object of this invention is to provide the rotary atomization type coating device which can prevent effectively that a coating material adheres and stays in a seal part, and can prevent the coating-film quality from falling.
[0009]
[Means for Solving the Problems]
The object of the present invention is achieved by the following means.
[0011]
( 1 ) In a rotary atomizing coating apparatus provided with an atomizing head that is provided on the front end side of a hollow rotating shaft and is rotationally driven and sprays paint from the front side.
A non-rotating paint supply pipe disposed in the central hole of the rotating shaft and supplying paint to the atomizing head;
A seal portion provided on the atomization head with a predetermined gap between the paint supply pipe exposed from the tip of the rotating shaft, and
The seal portion is characterized in that a shape of an inner end portion closest to the outer peripheral surface of the paint supply pipe is substantially free from a portion formed in parallel with the axial direction of the paint supply pipe. Rotating atomizing coating equipment.
[0012]
( 2 ) The rotary atomizing coating apparatus according to ( 1 ) above, wherein the inner end has a sharp cross-sectional shape.
[0013]
( 3 ) The rotary atomizing coating apparatus according to ( 1 ) above, wherein the inner end portion has a circular arc shape in cross section.
[0014]
( 4 ) In a rotary atomizing coating apparatus provided with an atomizing head that is provided on the front end side of a hollow rotating shaft and is rotationally driven and sprays paint from the front side.
A non-rotating paint supply pipe disposed in the central hole of the rotating shaft and supplying paint to the atomizing head;
A seal portion provided on the atomization head with a predetermined gap between the paint supply pipe exposed from the tip of the rotating shaft, and
The seal portion is a spiral groove that feeds the paint having the shape of the inner end closest to the outer peripheral surface of the paint supply pipe to the front side of the atomizing head as the atomizing head rotates. A rotary atomizing coating device characterized by its shape.
[0015]
( 5 ) The rotary atomization type according to any one of (1) to ( 4 ), wherein the seal portion is formed of a material having water repellency or oil repellency with respect to the paint. Painting equipment.
( 6 ) In a rotary atomizing coating apparatus provided with an atomizing head that is provided on the front end side of a hollow rotating shaft and is rotationally driven and sprays paint from the front side.
A non-rotating paint supply pipe disposed in the central hole of the rotating shaft and supplying paint to the atomizing head;
A seal portion provided on the atomization head with a predetermined gap between the paint supply pipe exposed from the tip of the rotating shaft, and
The seal portion has a rotary atomizing paint characterized in that the inner end portion closest to the outer peripheral surface of the paint supply pipe has a circular arc shape in a cross section by a plane including the rotation center of the rotation shaft. apparatus.
[0016]
【The invention's effect】
The present invention configured as described above has the following effects.
[0017]
According to the invention described in claim 1 , claim 2, or claim 3 , the conventional fixed idea that it is necessary to set the axial length of the inner end portion of the seal portion as long as possible is overcome. By defining the shape of the inner end in such a way that there is substantially no part formed in parallel to the axial direction of the paint supply pipe, the paint stays in the seal part basically and does not atomize. The solid content in the paint due to the rotation of the head does not deposit on the inner end surface of the seal portion, grow and peel off, and the deterioration of the coating film quality can be prevented.
[0019]
According to the invention described in claim 4 , by defining the shape of the inner end portion in a spiral groove shape that feeds the attached paint to the front side of the atomizing head as the atomizing head rotates, Even if paint enters the seal part, it is sent to the front side of the atomizing head through the spiral groove and scraped off from the tip of the seal part, so that the solid content of the paint can be further prevented. Therefore, the same effect as that of the first aspect of the invention can be obtained.
[0020]
According to the fifth aspect of the present invention, it is ensured that the paint adheres and stays on the seal portion by utilizing the effect that the material of the seal portion has water repellency or oil repellency to the paint. It is possible to further prevent the deterioration of the coating film quality.
According to the invention described in claim 6 , the retention of the paint in the seal portion is fundamental by defining the shape of the inner end portion to a shape having a cross-sectional arc shape in a cross section by a plane including the rotation center of the rotation shaft. The effect similar to that of the first aspect of the invention can be obtained.
[0021]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0022]
(First embodiment)
FIG. 1 is a cross-sectional view showing the structure of the tip of the rotary atomizing coating apparatus 10 according to the first embodiment of the present invention, and FIG. 2 is a diagram of the atomizing head 13 according to the first embodiment of the present invention. It is sectional drawing which expands and shows the seal | sticker part 15 vicinity.
[0023]
As shown in FIG. 1, a rotary atomizing electrostatic coating apparatus 10 includes a hollow shaft 12 (corresponding to a hollow rotating shaft) rotated by an air motor (not shown) provided in a housing 11, and a hollow shaft. An atomizing head 13 which is screwed to the front end side of the screw 12 and is rotationally driven and sprays paint from the front side, and is disposed on the rotation center in the center hole 12a of the hollow shaft 12 and supplies the paint to the atomizing head 13. The non-rotating feed tube 14 (corresponding to the paint supply pipe) and the feed tube 14 exposed from the tip of the hollow shaft 12 are provided on the atomizing head 13 with a predetermined gap therebetween, and the paint adheres thereto. And a seal portion 15 having a paint adhesion preventing structure that prevents the stagnation. The outer periphery of the housing 11 is covered with a housing 16 made of an electrically insulating material.
[0024]
The electrostatic coating apparatus 10 causes charged paint particles to fly along an electrostatic field formed between the objects and the object to be coated. Further, a high-speed air flow called shaping air is blown out from the air outlet 17 from the back side of the atomizing head 13, and the paint particles atomized by the atomizing head 13 are coated in front of the atomizing head 13. It is deflected in the direction toward the object. The paint particles are imparted with the momentum necessary to reach the object even by the shaping air. Reference numeral 18 indicates an air guide for guiding the shaping air ejected from the air ejection port 17 toward the atomizing head 13.
[0025]
The feed tube 14 is composed of a double pipe including an inner pipe 20 and an outer pipe 21 through which the inner pipe 20 is inserted. The inner pipe 20 is supplied with paint, and the outer pipe 21 is used for automatic cleaning. Thinner is supplied. The tip of the feed tube 14 is exposed from the tip of the hollow shaft 12 and extends toward the inside of the atomizing head 13. A paint valve is provided on the base end side of the feed tube 14, and this paint valve communicates with a paint tank (both not shown) via a paint pipe.
[0026]
The atomizing head 13 has a substantially cup shape, and has a cup-shaped outer peripheral surface 30, an inner peripheral-side paint smooth surface 31, and a front-end-side paint discharge edge 32. The atomizing head 13 is made of a conductive material such as metal. In the atomizing head 13, a paint inflow chamber 34 is defined by the bell hub portion 33, and the tip opening of the feed tube 14 communicates with the paint inflow chamber 34. The bell hub portion 33 is formed with a central opening 35 located in the central portion and a number of paint outlet holes 36 located in the peripheral portion. The large number of paint outlet holes 36 are arranged circumferentially at predetermined intervals. The atomizing head 13 is rotated at a high speed of about 35,000 rpm, for example, at the time of painting. Although not shown in the drawings, the coating discharge end edge 32 is formed with fine irregularities for atomizing the coating spread in a liquid film shape along the coating smooth surface 31.
[0027]
The seal portion 15 is formed of a material having water repellency or oil repellency with respect to the paint. Specifically, the material of the seal portion 15 is a fluorine-based resin such as PFA (perfluoroalkoxy fluororesin), FEP (tetrafluoroethylene hexafluoropropylene copolymer). Although it is conceivable to form the entire atomizing head 13 from the above-mentioned fluorine-based resin, there is no rigidity that can withstand high-speed rotation, and there is a possibility that the atomizing head 13 swells outward and is damaged. For this reason, the atomizing head 13 is configured by fitting a seal portion 15, which is a resin processed product, into an inner portion of the main body portion 37 formed of metal or the like.
[0028]
Seal air guided through a space formed between the hollow shaft 12 and the feed tube 14 is supplied to the gap 50 between the seal portion 15 and the feed tube 14. The pressure and flow rate of the sealing air are set to such an extent that the gap 50 is prevented from becoming negative pressure and the paint is not sucked, as in the conventional case. The effect of blowing the paint that has entered the gap 50 is Absent.
[0029]
A high voltage generator (not shown) is electrically connected to the hollow shaft 12 made of a conductive material, and a DC voltage of, for example, about −60 to −90 kV is applied to the atomizing head 13 through the hollow shaft 12. Thereby, the paint particles sprayed from the atomizing head 13 are charged.
[0030]
The air jet 17 is formed in an annular shape between the first air ring 41 and the second air ring 42, and the air guide 18 is formed by the outer peripheral surface of the first air ring 41. The first air ring 41 is attached to the distal end portion of the housing 16. An annular air passage is formed between the housing 11 and the housing 16, and an air introduction hole 43 is formed in the first air ring 41 to connect the air jet port 17 and the air passage. The air supplied to the air passage via an air pipe (not shown) passes through the air introduction hole 43 and is ejected as shaping air from the air ejection port 17. The air rings 41 and 42 are made of, for example, an electrically insulating material such as PEEK (polyether ether ketone), POM (polyacetal), or PFA. The housing 16 is also formed from a similar electrically insulating material.
[0031]
The paint adhesion preventing structure of the seal portion 15 in the first embodiment is formed closest to the outer peripheral surface of the feed tube 14 and parallel to the axial direction of the feed tube 14 as shown in an enlarged view in FIG. It is configured by defining the axial length a of the inner end 51 to a predetermined dimension.
[0032]
An experiment is performed in which coating is performed under a plurality of combinations of the axial length a of the inner end 51 and the gap dimension b between the inner end 51 and the outer peripheral surface of the feed tube 14 to determine the coating quality. It was. From this experimental result, it was found that the axial length a of the inner end portion 51 should be defined within twice the gap dimension b.
[0033]
FIG. 3 shows a graph of the experimental results. The vertical axis of the graph indicates the axial length a, and the horizontal axis indicates the gap dimension b. A white circle indicates that the determination result is OK, and a black circle indicates that the determination result is NG. A line segment indicated by a broken line in the drawing represents the function a = 2b.
[0034]
In the region above the line segment of a = 2b, that is, in the region satisfying a> 2b, the paint stays at the inner end portion 51, and solids such as pigments are deposited and grow, so The coating quality was judged to be NG in all cases due to the occurrence of the coating or the non-uniform coating state of the paint.
[0035]
On the other hand, in the region below the line segment of a = 2b, that is, the region satisfying a ≦ 2b, the coating quality judgment result was OK in all cases. The inner end 51 parallel to the center of rotation is subject to centrifugal separation accompanying rotation, and the solid content of the paint is likely to be deposited. However, in the region where a ≦ 2b is satisfied, the portion parallel to the center of rotation is a gap. It is relatively short with respect to the dimension b, and it does not grow so large that the solid content in the paint becomes “pox”. In this experiment, it was confirmed that the paint did not remain on the inner end portion 51. Since the situation where the solid content grows on the surface of the inner end portion 51 does not occur fundamentally, it can be inferred that good coating quality can be obtained. Further, due to the water repellency or oil repellency effect on the paint provided by the fluororesin that is the material of the seal portion 15, the liquid paint originally hardly enters the gap 50, and it is ensured that the paint adheres and stays on the seal portion 15. From this viewpoint, it can be inferred that good coating quality can be obtained.
[0036]
In addition, although the experiment was performed in the range where the gap dimension b is 0.3 to 1.0 mm, in the actual machine, the gap dimension b is the surface tension of the paint, the ease of penetration into the gap 50, and the solvent thinner. However, it is usually set in the range of 0.3 to 0.8 mm, preferably in the range of 0.5 to 0.6 mm. The tip of the feed tube 14 protrudes from the inner end portion 51 to the tip side (the atomizing head 13 side) by about 3 to 5 mm.
[0037]
Next, the operation will be described.
[0038]
The hollow shaft 12 and the atomizing head 13 are rotated at high speed by an air motor. The paint is guided to the paint inflow chamber 34 through the feed tube 14 and supplied to the front surface of the atomizing head 13 from the central opening 35 and the paint outlet hole 36. The supplied paint is thinly stretched along the paint smooth surface 31 by the centrifugal force generated by the rotation of the atomizing head 13, atomized from the paint discharge edge 32 and discharged.
[0039]
The discharged paint particles try to jump out radially outward by centrifugal force. However, the discharged paint particles are controlled or shaped into a desired pattern so as to be squeezed forward by the shaping air ejected from the air ejection port 17 and are carried toward the object to be coated.
[0040]
Furthermore, the charged paint particles fly toward the object to be coated connected to the ground, and efficiently adhere to the surface of the object to be coated by Coulomb force.
[0041]
In the coating apparatus 10 of the first embodiment, the inner end portion 51 is formed in parallel with the axial direction of the feed tube 14, and the axial length a of the inner end portion 51 is within twice the gap dimension b. Therefore, it is possible to prevent the paint from adhering to the seal portion 15 and staying there. Therefore, the solid content in the paint due to the rotation of the atomizing head 13 does not deposit and grow on the surface of the inner end portion 51 of the seal portion 15, and finally the seal portion does not peel off as a lump. As a result, “pops” do not adhere to the painted surface and the sprayed state of the paint does not become uneven, and it is possible to prevent deterioration of the coating film quality.
[0042]
(Second Embodiment)
FIG. 4 is an enlarged sectional view showing the vicinity of the seal portion 15a of the atomizing head 13 according to the second embodiment of the present invention. Note that members that are the same as those shown in FIG. 1 are given the same reference numerals, and descriptions thereof are partially omitted.
[0043]
The second embodiment is common to the first embodiment in that a seal portion 15a having a paint adhesion prevention structure is provided on the atomizing head 13, but the second embodiment is different in terms of a specific configuration of the paint adhesion prevention structure. This is different from the first embodiment.
[0044]
The paint adhesion prevention structure of the seal portion 15a in the second embodiment is configured by defining the shape of the inner end portion 52 closest to the outer peripheral surface of the feed tube 14 to a predetermined shape.
[0045]
The shape of the inner end portion 52 is defined as a shape in which a portion formed in parallel with the axial direction of the feed tube 14 does not substantially exist. Specifically, as shown in FIG. 4, the shape of the inner end portion 52 has an acute cross-sectional shape and serves as an edge seal.
[0046]
According to the shape of the inner end portion 52, since the portion parallel to the feed tube 14 does not originally exist on the side of the atomizing head 13 that is subjected to centrifugal separation, it is fundamental that the paint adheres to the seal portion 15a and stays there. Does not occur. As a result of effectively preventing stagnation of the paint in the seal portion 15a, there is no possibility that “spots” adhere to the painted surface or the spray state of the paint becomes uneven as in the first embodiment. It is possible to prevent deterioration of coating film quality.
[0047]
Since there is no portion parallel to the feed tube 14 in the seal portion 15a, the paint may flow backward to the hollow shaft 12 side. However, even if the paint flows backward, the paint remains at least inside the hollow shaft 12. Therefore, the paint that has flowed back can be easily removed by performing periodic cleaning using thinner or the like.
[0048]
In addition, paint may adhere to the outer peripheral surface of the feed tube 14, but since the paint is not subjected to the centrifugal separation action, it remains liquid without being deposited. Therefore, it can be easily washed.
[0049]
In order to prevent the paint from flowing back to the hollow shaft 12 as much as possible, a fluororesin is used as the material of the seal portion 15a as in the first embodiment, and the paint with which the fluororesin is provided. It is preferable to use the effect of water repellency or oil repellency.
[0050]
5 and 6 are cross-sectional views showing other examples of the shape of the inner end portion.
[0051]
The shape of the inner end portion may be defined as a shape in which a portion formed in parallel with the axial direction of the feed tube 14 does not substantially exist, and the specific shape is not limited to the acute-angle cross-sectional shape described above. .
[0052]
For example, as shown in FIG. 5, the inner end portion 53 having a sharp cross-sectional arc shape with a large curvature or the inner end portion 54 having a gentle cross-sectional arc shape with a small curvature as shown in FIG. 6 may be used. Even in the shapes of these inner end portions 53 and 54, as described above, it is possible to effectively prevent the paint from adhering to and staying on the seal portion 15a, and as a result, it is possible to prevent deterioration of the coating film quality. .
[0053]
(Third embodiment)
FIG. 7 is an enlarged cross-sectional view showing the vicinity of the seal portion 15b of the atomizing head 13 according to the third embodiment of the present invention. Note that members that are the same as those shown in FIG. 4 are given the same reference numerals, and descriptions thereof are partially omitted.
[0054]
The third embodiment is common to the second embodiment in that the paint adhesion preventing structure is configured by defining the shape of the inner end portion 55 to a predetermined shape, but the specific shape of the inner end portion 55 is not limited. This is different from the second embodiment.
[0055]
The paint adhesion prevention structure of the seal portion 15b in the third embodiment is such that the shape of the inner end portion 55 is sent to the front side of the atomizing head 13 as the atomizing head 13 rotates. It is prescribed. Specifically, the inner end portion 55 has a spiral groove shape. The spiral groove 56 is carved so that the force component along the rotational axis direction of the centrifugal force accompanying the rotation of the atomizing head 13 faces the front side of the atomizing head 13 shown on the left hand side in the drawing.
[0056]
According to the shape of the inner end 55, even if the paint enters the seal portion 15b, the paint travels through the spiral groove 56 by the force component along the rotation axis direction of the centrifugal force. 13 is actively sent out toward the front surface side of 13 and finally scraped off from the tip of the seal portion 15b, so that the solid content of the paint can be further prevented.
[0057]
Therefore, as in the second embodiment, it is possible to effectively prevent the coating material from adhering to and staying on the seal portion 15b. As a result, it is possible to prevent deterioration of the coating film quality.
[0058]
It should be noted that the method of the second embodiment is adopted at the tip of the thread, and the shape formed in parallel with the axial direction of the feed tube 14 is defined as a shape that does not substantially exist, for example, an acute cross-sectional shape or a cross-sectional arc shape. Is preferred.
[0059]
Further, in order to facilitate the movement of the paint in the spiral groove 56, as in the first embodiment, a fluorine resin is used as the material of the seal portion 15b, and the water repellency to the paint provided in the fluorine resin is reduced. It is better to use the effect of oil repellency.
[0060]
(Other modifications)
In the first to third embodiments described above, the example in which the atomized head 13 is configured by fitting the resin processed product constituting the seal portions 15, 15 a, and 15 b into the main body portion 37 is shown. A configuration in which a predetermined part is coated with a fluorine-based resin may be employed.
[0061]
In addition, the direct charging type coating apparatus 10 that directly applies a high voltage to the paint from the high voltage generator is illustrated. However, the present invention applies a high voltage to the paint sprayed from the atomizing head 13 via an external electrode. Needless to say, the present invention can also be applied to an indirect charging type coating apparatus that applies s.
[0062]
Further, the feed tube 14 as the paint supply pipe is not limited to the illustrated double pipe, but is a feed tube constituted by one paint pipe or a feed in which a plurality of paint pipes are bundled. Tubes are also included in the concept of “paint supply pipe”.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing a structure of a tip portion of a rotary atomizing coating apparatus according to a first embodiment of the present invention.
FIG. 2 is an enlarged cross-sectional view showing the vicinity of the seal portion of the atomizing head according to the first embodiment of the present invention.
FIG. 3 is a graph showing experimental results.
FIG. 4 is an enlarged sectional view showing the vicinity of a seal portion of an atomizing head according to a second embodiment of the present invention.
FIG. 5 is a cross-sectional view showing another example of the shape of the inner end portion.
FIG. 6 is a cross-sectional view showing another example of the shape of the inner end portion.
FIG. 7 is an enlarged sectional view showing the vicinity of a seal portion of an atomizing head according to a third embodiment of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 ... Rotary atomization type coating apparatus 12 ... Hollow shaft (hollow rotating shaft)
12a ... Center hole 13 ... Atomizing head 14 ... Feed tube (paint supply tube)
15, 15a, 15b ... seal part 50 ... gaps 51, 52, 53, 54, 55 ... inner end part 56 ... spiral groove a ... axial length b of inner end part ... inner end part and paint supply pipe outer periphery Gap dimension between faces

Claims (6)

In a rotary atomizing coating apparatus provided with an atomizing head that is provided on the front end side of a hollow rotating shaft and is rotationally driven and sprays paint from the front side,
A non-rotating paint supply pipe disposed in the central hole of the rotating shaft and supplying paint to the atomizing head;
A seal portion provided on the atomizing head with a predetermined gap between the paint supply pipe exposed from the tip of the rotating shaft, and
The seal portion is characterized in that a shape of an inner end portion closest to the outer peripheral surface of the paint supply pipe is substantially free from a portion formed in parallel with the axial direction of the paint supply pipe. Rotary atomizing coating equipment. The rotary atomizing coating apparatus according to claim 1, wherein the shape of the inner end portion has an acute-angle cross section . The rotary atomizing coating apparatus according to claim 1 , wherein the inner end portion has a circular arc shape in cross section . In a rotary atomizing coating apparatus provided with an atomizing head that is provided on the front end side of a hollow rotating shaft and is rotationally driven and sprays paint from the front side,
A non-rotating paint supply pipe disposed in the central hole of the rotating shaft and supplying paint to the atomizing head;
A seal portion provided on the atomizing head with a predetermined gap between the paint supply pipe exposed from the tip of the rotating shaft, and
The seal portion is a spiral groove that feeds the paint having the shape of the inner end closest to the outer peripheral surface of the paint supply pipe to the front side of the atomizing head as the atomizing head rotates. A rotary atomizing coating device characterized by its shape . The rotary atomizing coating apparatus according to any one of claims 1 to 4, wherein the seal portion is formed of a material having water repellency or oil repellency with respect to the paint. In a rotary atomizing coating apparatus provided with an atomizing head that is provided on the front end side of a hollow rotating shaft and is rotationally driven and sprays paint from the front side,
A non-rotating paint supply pipe disposed in the central hole of the rotating shaft and supplying paint to the atomizing head;
A seal portion provided on the atomization head with a predetermined gap between the paint supply pipe exposed from the tip of the rotating shaft, and
The seal portion has a rotary atomizing paint characterized in that the inner end portion closest to the outer peripheral surface of the paint supply pipe has a circular arc shape in a cross section by a plane including the rotation center of the rotation shaft. apparatus.

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