JPH09168753A - Rotary atomizing electrostatic coating apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a rotary atomizing electrostatic coating apparatus having an air supply structure for preventing the back flow of coating material without bringing about scaling-up or a cost increase by providing a branch part dividing air flow for preventing the back flow of the coating material on the way of the suction passage to either one of an air bearing, a turbine and a shaping air cap. SOLUTION: Compressed air (air for preventing the back flow of coating material) is supplied to the hollow part of a rotary shaft 18 in order to prevent the back flow of coating material or a washing agent or to enhance upward coating properties. A branch part 26 dividing air flow for preventing the back flow of coating material is provided on the way of the air supply passage to at least either one of an air bearing, a turbine and a shaping air cap. By this constitution, the supply passage of air for preventing the back flow of coating material and a compressed air supply source are used in common with the supply passage of at least one of the air for the air bearing, the air for the turbine and the air for the shaping air cap and the compressed air supply source thereof. As a result, it becomes unnecessary to provide an exclusive passage for air preventing the back flow of coating material in a housing.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rotary atomizing electrostatic coating apparatus, and more particularly to a rotary atomizing electrostatic coating apparatus of the type in which paint backflow preventing air is supplied to the hollow portion of a rotary shaft. Regarding the air supply structure.

[0002]

2. Description of the Related Art FIG. 5 shows an outline of a rotary atomizing electrostatic coating apparatus which has recently become mainstream. The rotary atomizing electrostatic coating device
Mainly, air motor 1, bell head 2, shaping air cap 3, high voltage generator 4, paint feed tube 5
It is composed of As a bearing of the air motor 1 of the rotary atomizing electrostatic coating device, a static pressure air bearing 7 is mainly used. Since the static pressure air bearing 7 supplies air pressurized from the outside to the gap between the bearing and the rotary shaft 8 to float the rotary shaft 8, it is non-contact, completely oil-free, and excellent in durability. Further, the bell head 2 fastened to the rotary shaft 8 is driven by supplying compressed air to the turbine blades 6 on the rotary shaft 8. As described above, in order to drive the static pressure air bearing type rotary atomizing electrostatic coating device, at least two independent paths of the bearing air and the turbine air are required (in addition, the brake air for decelerating the rotation is used. Often have). Conventionally, there is one in which air is supplied to a hollow rotary shaft to prevent backflow of paint and thinner into the rotary shaft and to improve upward paintability (for example, Japanese Patent Application No. 5-31).
7641), in that case, in addition to the above air path,
Further, a dedicated air supply route and its air supply source different from the above air route were required.

[0003]

However, the rotary atomizing electrostatic coating apparatus having the dedicated air supply path and the air supply source for preventing backflow of paint and the like has the following problems. Since various structures and paths are built around the air motor, it is difficult to provide an air supply path for preventing backflow of paint and the like. Moreover, even if it can be provided, the size of the rotary atomizing electrostatic coating device is increased accordingly. As a result, the cost of the rotary atomizing electrostatic coating device increases. An object of the present invention is to provide an air supply structure for preventing paint backflow with almost no additional air supply path, large-sized rotary atomization electrostatic coating device, increased cost of rotary atomization electrostatic coating device, etc. An object is to provide a rotary atomizing electrostatic coating device having the same.

[0004]

The present invention to achieve the above object is as follows. (1) A rotary atomizing electrostatic coating device in which paint backflow prevention air is supplied to a hollow portion of a rotating shaft, in the middle of an air supply passage to at least one of an air bearing, a turbine, and a shaping air cap. A rotary atomizing electrostatic coating device provided with a branch portion for branching the paint backflow preventing air. (2) Among the air supply passages to the air bearing, the turbine, and the shaping air cap, the passage cross-sectional area of the upstream side portion of the branch portion of the passage where the branch portion is provided is calculated as follows. The rotary atomizing electrostatic coating device according to (1), which is larger than the passage cross-sectional area. (3) The rotary shaft is rotatably supported by two radial bearings and one thrust bearing that are separated in the axial direction of the rotary shaft, and the thrust bearing is arranged between the two radial bearings. Of the radial bearing, the branch portion is arranged in a rear first housing portion of the rear radial bearing, and a radial gap is formed between the first housing portion and the rotary shaft. An axial gap that communicates with the radial gap is formed between the rear end and a second housing portion that opposes the axial direction of the rotation axis, and the backflow prevention of the paint that is shunted from the branch portion in the first housing portion is formed. The rotary atomizing electrostatic coating device according to (1), wherein an air nozzle is formed so as to flow the use air into the radial gap.

In the above device (1), at least a part of at least one of the bearing air, the turbine air, and the shaping air is diverted so as to flow back into the rotary shaft as backflow preventing air such as paint. As described above, it is not necessary to additionally provide a dedicated supply passage and an air supply source for the paint backflow prevention air, so that the size of the apparatus is not increased and the cost is hardly increased. In the device of the above (2), since the passage cross-sectional area on the upstream side of the branch portion is made large, even if the air is supplied by increasing the air amount by the paint backflow prevention air, the pressure loss on the upstream side of the branch portion is small. , Bearing air, turbine air,
The pressure drop of the shaping air is small and is almost unaffected by the paint backflow prevention air, and the operation is stable. The above (3)
In this device, since the bearing is blocked from the rear end of the rotary shaft by the axial gap and the radial gap, the paint does not reach the bearing even if the paint enters the rear end of the rotary shaft.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION A rotary atomizing electrostatic coating apparatus according to a preferred embodiment of the present invention will be described with reference to FIGS. FIG. 1 relates to the first embodiment of the present invention, FIG. 2 relates to the second embodiment of the present invention, and FIGS. 3 and 4 show the first and second embodiments of the present invention.
It is commonly applied to the embodiments. Portions common to all embodiments of the present invention are denoted by the same reference numerals throughout all embodiments of the present invention.

First, the structure and operation of the parts common to all the embodiments of the present invention will be described with reference to, for example, FIGS. 1, 3 and 4. Referring to FIG. 1, a rotary atomizing electrostatic coating device 10 according to an embodiment of the present invention includes a housing 19, and a hollow rotary shaft 18 rotatably supported by a radial static pressure air bearing (air bearing) 17 in the housing 19. Thrust hydrostatic air bearing 2 that rotatably supports the axial load applied to the rotary shaft 18.
1, a bell head (rotary atomizing head) 12 fixed to the front end of the rotary shaft 18 and rotating integrally with the rotary shaft 18, and a rotary shaft 1
An air motor 11 for rotating 8; a paint feed tube 15 that extends through the hollow portion of the rotary shaft 18 to supply paint to the bell head 12; and a cleaning agent feed tube 20 that supplies cleaning agent (thinner) to the bell head 12.
Shaping air cap 1 for adjusting the flight pattern of paint sprayed from the bell head 12 toward the paint
3 and a high voltage generator 14 supported by a housing 19 that generates a high voltage to add an electric charge to the paint scattered from the bell head 12.

The rotary atomizing electrostatic coating device 10 further includes a radial static pressure air bearing 17 and a thrust static pressure air bearing 2.
1, a bearing air passage 22 for supplying bearing air to 1, a turbine air passage 23 for supplying turbine air to the turbine 16 of the air motor 11, and a turbine exhaust passage 24 for exhausting air after rotating the turbine, and shaping. A shaping air passage 25 for supplying air to the shaping air cap 13, and each passage has a housing 1
A part of it is formed inside 9.

Compressed air (hereinafter referred to as "compressed air") is used in order to prevent backflow of paints and cleaning agents or to improve upward paintability.
Paint backflow prevention air) is supplied to the hollow portion of the rotary shaft 18. In the embodiment of the present invention, the branch portion 26 for diverting the paint backflow prevention air is provided in the middle of the air supply passage to at least one of the air bearing, the turbine, and the shaping air cap. As a result, the paint backflow prevention air supply passage and its compressed air supply source are at least one of air bearing air, turbine air, and shaping air.
It is shared with one supply passage and its compressed air supply source.
Therefore, a dedicated supply passage for the paint backflow prevention air and its dedicated compressed air supply source are not provided. As a result, it is not necessary to provide a dedicated passage for the paint backflow prevention air in the housing, and there is no need to upsize the housing, and the cost can be reduced.

Of the air supply passages to the air bearing, the turbine and the shaping air cap, the passage cross-sectional area of the upstream portion 26a of the branch portion 26 of the passage where the branch portion 26 is provided is the downstream portion 26b of the branch portion 26. It is larger than the cross-sectional area of the passage. The backflow prevention air requires a considerable amount of air (for example, 5 to 100 liters / minute), and when it is used in common with at least one of air bearing air, turbine air, and shaping air, the loss is that much. , It is necessary to consider the resistance. When the cross-sectional area of the passage on the upstream side of the branch portion 26 is made the same as when the backflow prevention air is not flowed,
At least one of the air for the air bearing, the turbine air, and the shaping air and the resistance of the backflow prevention air are applied, and the proper pressure is secured at the inlet of either the air bearing, the turbine, or the shaping air cap. It is necessary and its design is very difficult. However, in the embodiment of the present invention, since the passage cross-sectional area of the upstream portion 26a of the branch portion 26 is set to be larger than the passage cross-sectional area of the downstream portion 26b of the branch portion 26, the resistance at the upstream portion 26a of the branch portion 26 is increased. , Even if at least one of the air bearing air, the turbine air, and the shaping air and the backflow prevention air are made to flow at the same time due to the reduced pressure loss, at the inlet of either the air bearing, the turbine, or the shaping air cap. It becomes possible to secure an appropriate pressure.

The rotary shaft 18 includes two radial bearings 17 and one thrust bearing 2 which are separated from each other in the axial direction of the rotary shaft 18.
1 is rotatably supported, and the thrust bearing 21 is disposed between the two radial bearings 17. The branch portion 26 is
The housing 19 is arranged in a first housing portion 19a behind the rear radial bearing 17a of the two radial bearings 17. A radial gap 27 is formed between the first housing portion 19a and the rotary shaft 18, and between the rear end of the rotary shaft 18 and the second housing portion 19b that faces the rotary shaft 18 in the rotary shaft axial direction. An axial gap 28 communicating with the radial gap 27 is formed. Then, the branch portion 2 is provided in the first housing portion 19a.
The paint backflow prevention air diverted from 6 is passed through the radial gap 27.
An air nozzle 29 is formed to allow the air to flow out. The radial clearance 27 is preferably thicker than the axial clearance 28.

With this structure, the paint backflow preventing air is branched at the branching portion 26 and then ejected from the air nozzle 29 into the radial gap 27 and then into the axial gap 28.
After passing through the axial gap 28, it rotates around the rear end of the rotary shaft 18 and flows into the hollow portion, and the rotary shaft 18 passes through the hollow portion of the rotary shaft 18.
Flows to the front end of the rotary shaft and flows out from the front end of the rotary shaft. When the paint or thinner is discharged from the front end of the rotary shaft 1,
Prevent backflow into 8. Also at the front end of the air motor, the paint-preventing air is jetted into the cavity 31 through the orifice 30, and is rotated in the circumferential direction and then discharged to the outside. There is an appropriate value for the flow rate of paint backflow prevention air,
Depending on the rotary shaft and the paint feed tube, 5 to 100 for each of the rear end and the front end of the rotary shaft, as described above.
It is in the range of about 1 liter / minute. If this amount is less than this range, the function of preventing backflow cannot be sufficiently fulfilled, and if it is more than this range, the paint cannot be discharged stably as shown in FIG. FIG. 3 is in the above range and shows a state in which the discharge of the paint is stable.

When the paint backflow prevention air is simply supplied from the rear end of the rotary shaft into the hollow portion of the rotary shaft as in the conventional example of FIG. 5, or the paint backflow prevention air is rotated from the middle of the longitudinal direction of the rotary shaft. When supplying paint into the hollow part of the shaft, once the paint etc. enters the hollow part of the rotating shaft, the centrifugal force applied to the paint etc. by the rotation of the rotating shaft quickly causes the paint, etc., to enter the rear bearing and make it unrotatable. Will end up. However, in the embodiment of the present invention, the rear bearing 17a includes the rotary shaft 1
8, the inner space 8 and the axial gap 28 and the radial gap 2
Since it is divided into two stages via 7,
Even if paint or thinner enters the inside of the bearing 8, it does not reach the rear bearing 17a and is prevented from becoming unrotatable.

Next, the structure and operation of the parts peculiar to each embodiment of the present invention will be described. In the first embodiment of the present invention, FIG.
As shown in FIG. 5, a branch portion 26 for dividing the paint backflow prevention air is provided in the middle of the bearing air passage 22. The passage from the branch portion 26 is connected to an air nozzle 29, and the paint backflow prevention air is ejected from the air nozzle 29 into the radial gap 27 and then flows into the rotary shaft 18 through the axial gap 28. In the second embodiment of the present invention, as shown in FIG. 2, a branch portion 26 for dividing the paint backflow prevention air is provided in the middle of the turbine air passage 23. The passage from the branch portion 26 is connected to an air nozzle 29, and the paint backflow prevention air is ejected from the air nozzle 29 into the radial gap 27 and then flows into the rotary shaft 18 through the axial gap 28. When the shaping air passage 25 passes through the air motor, the shaping air supply air may be distributed in the air motor. In that case, the branching portion 26 is located inside the air motor.

[0015]

According to the first aspect of the present invention, a branch portion is provided in at least one air supply passage of bearing air, turbine air, or shaping air to divert a part of the air supply to prevent backflow of paint or the like. As it is made to flow into the rotary shaft as described above, it is not necessary to additionally provide a dedicated supply passage for the paint backflow prevention air and an air supply source as in the conventional case, which does not lead to an increase in size of the apparatus. Almost no cost increase is invited. In the device of claim 2, since the passage cross-sectional area upstream of the branch portion is larger than the passage cross-sectional area downstream of the branch portion,
Even if the air flow is increased by increasing only the paint backflow prevention air, the pressure loss on the upstream side of the branch is small, and the pressure drop is small in all of the bearing air, turbine air, and shaping air. Hardly affected by the operating air,
The operation of each air is stable. In the device of claim 3, since the bearing is blocked from the rear end of the rotary shaft by the axial gap and the radial gap, the paint does not reach the bearing even if the paint enters the rear end of the rotary shaft. .

[Brief description of the drawings]

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

FIG. 2 is a sectional view of a rotary atomizing electrostatic coating device according to a second embodiment of the present invention.

FIG. 3 is a cross-sectional view of the front end portion of the rotary atomizing electrostatic coating device, showing a state in which the paint flows out from the end of the paint feed tube when the flow rate of the paint backflow prevention air is within an appropriate range.

FIG. 4 is a cross-sectional view of the front end portion of the rotary atomizing electrostatic coating device showing a state where the paint flows out from the end of the paint feed tube when the flow rate of the paint backflow prevention air is not within the proper range.

FIG. 5 is a sectional view of a conventional rotary atomizing electrostatic coating device.

[Explanation of symbols]

 10 Rotating Atomizing Electrostatic Coating Device 11 Air Motor 13 Shaping Air Cap 15 Paint Feed Tool 17 Static Pressure Air Bearing 18 Rotating Shaft 19 Housing 21 Thrust Static Pressure Air Bearing 22 Bearing Air Passage 22 23 Turbine Air Passage 23 25 Shaping Air Passage 26 Branch Part 26a Upstream side part 26b Downstream side part 27 Radial gap 28 Axial gap 29 Air nozzle

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Hiroshi Aizawa 1-5-50 Shinmei Kugenuma, Fujisawa-shi, Kanagawa Nippon Seiko Co., Ltd. (72) Toshinori Sato 1-5-50 Kumei, Kugenuma, Fujisawa-shi, Kanagawa Within NSK Ltd. (72) Inventor Jun Takahashi 1-5-50, Shinmei Kugenuma, Fujisawa City, Kanagawa Within NSK Ltd.

Claims (3)

[Claims] 1. A rotary atomizing electrostatic coating device in which paint backflow prevention air is supplied to a hollow portion of a rotary shaft, the air bearing comprising:
A rotary atomizing electrostatic coating device having a branching portion for dividing the paint backflow prevention air in the middle of an air supply passage to at least one of a turbine and a shaping air cap. 2. A passage cross-sectional area of an upstream side portion of the branch portion of a passage where the branch portion is provided among air supply passages to the air bearing, the turbine, and the shaping air cap is set to a downstream side of the branch portion. The rotary atomizing electrostatic coating device according to claim 1, wherein the cross sectional area of the passage is larger than that of the portion. 3. The rotary shaft is rotatably supported by two radial bearings and one thrust bearing separated in the axial direction of the rotary shaft, and the thrust bearing is arranged between the two radial bearings. Of the two radial bearings, the branch portion is arranged in a rear first housing portion of a rear radial bearing, and a radial gap is formed between the first housing portion and the rotary shaft, and the rotation is performed. A paint that forms an axial gap that communicates with the radial gap between the rear end of the shaft and a second housing part that faces the axial direction of the rotation shaft, and that is diverted from the branch part to the first housing part. The rotary atomizing electrostatic coating device according to claim 1, wherein an air nozzle is formed to flow backflow preventing air into the radial gap.