JPH09294942A - Rotary atomizing electrostatic coating apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a beautiful coating surface at high coating efficiency even in a narrow place which can be coated only by a spray gun by holding a bearing member supporting rotary shaft by a synthetic resin cover and embedding a high voltage generator in the cover. SOLUTION: Hollow rotary shafts 1 are floated and supported non- contactingly at an interval in the shaft direction by a pair of bearing members 2 of porous shaped static pressure gas bearings and rotated at a high speed by a turbine mechanism 3. A synthetic resin cover 5 which holds the pair of the bearing members 2 functions as a protection member from high voltage static electricity. A high voltage generator 8 for charging coating which is supplied through a coating supply pipe 6a and scattered by the rotation of a bell head 7 is embedded in the cover 5. A shaping air cap 9 for arranging the flight pattern of coating particles which are charged, atomized, and ejected from the bell head 7 to a material to be coated is fixed and installed projectingly on the end surface of the front cover 5b of the cover 5.

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 device, and more particularly to miniaturization thereof.

[0002]

2. Description of the Related Art A conventional rotary atomizing electrostatic coating device is shown in FIG. This is a mainstream recently, and a hollow rotary shaft A is levitationally supported by a pair of front and rear bearing members B of hydrostatic gas bearings in a non-contact manner and rotated at a high speed by a turbine mechanism C. The bearing member B is fixedly held by a housing E made of aluminum or stainless steel, and the outer surface of the housing E is covered with a synthetic resin cover F which is an exterior member which functions as a protection member against high-voltage static electricity. There is. Then, the paint and the thinner supplied through the hollow portion of the rotating shaft A placed in the electrostatic field of high voltage formed by the high voltage generator G are sent to the bell head H rotating at high speed at the tip of the rotating shaft A. , Sprayed on the object to be coated as charged and atomized paint particles.

[0003]

However, in the conventional rotary atomizing electrostatic coating apparatus described above, the bearing member B is supported by the metal housing E, and the synthetic resin cover F for protection against high-voltage static electricity is further provided. It is exterior. By the way,
In order to ensure a very narrow radial bearing gap and axial bearing gap between the bearing member B and the rotary shaft A, not only the two members A and B but also a component such as a housing E that holds and holds the bearing member B is fixed. High precision is required. For this reason,
As the housing E, a metal housing which is easily processed with high precision is inevitably adopted.
As described above, in the conventional rotary atomizing electrostatic coating device, the housing E and the synthetic resin cover F that covers the housing E have to have a so-called double housing structure. It was difficult to reduce the size, and it was inevitable that the size would be rather large. Therefore, there is a problem that such a large rotary atomizing electrostatic coating device cannot be used in a portion where the space is small.

Therefore, an object of the present invention is to provide a small rotary atomizing electrostatic coating device which has the same coating performance as the conventional one and is capable of coating a portion which can be coated only by a spray gun. Especially.

[0005]

To achieve the above object, a rotary atomizing electrostatic coating apparatus according to claim 1 of the present invention supports a rotary shaft with a bearing member, and the bearing member is made of synthetic resin. It is held by a cover made of synthetic resin, and a high voltage generator is embedded in the cover made of synthetic resin.

Since the rotary atomizing electrostatic coating device of the present invention is basically constructed in this way, the bearing member can be directly held by the resin cover without the metal housing. The housing can be omitted and the entire apparatus can be downsized.

Here, in the rotary atomizing electrostatic coating device according to the first aspect of the present invention, the cylindrical bearing member has gas ejection portions on its inner peripheral surface and both end surfaces, and the rotary shaft is provided in the inner peripheral surface of the bearing member. And the bearing members are respectively disposed on both sides of a flange portion integrally formed in the axially intermediate portion of the rotary shaft, and each bearing member is elastically supported and held by the inner hole of the synthetic resin cover. ,
A thrust bearing gap is formed between one end face of each bearing member and a flange end face of the rotating shaft facing the one end face, and a synthetic resin facing the other end face of the bearing member and the other end face. A thrust direction gap may be formed between each of them and the manufactured cover.

When the rotary atomizing electrostatic coating apparatus of the present invention is constructed in this manner, the bearing member is supported in a floating state on the synthetic resin cover, so that the rotary shaft and the bearing member are highly accurate. Even if the above processing is required, the function of the synthetic resin cover that holds the bearing member is not impaired even with a rougher dimensional accuracy. That is, the synthetic resin cover, which is difficult to obtain dimensional accuracy, can hold the bearing member, and thus the rotary atomization electrostatic coating device that is small and lightweight and has excellent insulation properties can be provided at low cost.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of a rotary atomizing electrostatic coating apparatus of the present invention will be described below with reference to FIG. 1 showing a cross section of the entire structure, FIG. 2 showing another cross section thereof, and FIG. Explain.

In this rotary atomizing electrostatic coating device, a hollow rotary shaft 1 is supported by a pair of porous static pressure gas bearings, which are bearing members 2 which are levitationally supported in a non-contact manner at intervals in the axial direction. The turbine mechanism 3 rotates at high speed. The synthetic resin cover 5 that holds the pair of bearing members 2 functions as a protection member against high-voltage static electricity. A non-rotating paint supply pipe 6a and a thinner supply pipe 6b are inserted through the inner hole of the rotating shaft 1, and the front cover 5b of the synthetic resin cover 5 is provided at the front of the housing body 5c of the synthetic resin cover 5. Is fixed. A bell head 7, which is a coating jig for spraying and atomizing the supplied paint, is integrally rotatably attached to the tip of the rotary shaft 1 that projects leftward from the front cover 5b.

Inside the synthetic resin cover 5, there is embedded a high voltage generator 8 for adding an electric charge to the paint supplied through the paint supply pipe 6a and scattered by the rotation of the bell head 7. Further, a shaping air cap 9 for fixing the flight pattern of paint particles sprayed from the bell head 7 onto the object to be coated is fixed to the tip surface of the synthetic resin front cover 5b of the synthetic resin cover 5. It is projected. Also, the rear end surface 5d of the synthetic resin cover 5
The bearing air supply passage 11 for supplying bearing air to the bearing member 2, the turbine air supply passage 12 for supplying turbine air to the turbine mechanism 3, the air after rotating the turbine and the bearing member 2. An air exhaust path 13 for exhausting jetted air, a shaping air supply path 1 for supplying shaping air to the shaping air cap 9.
Openings 4 and the like are arranged around the paint / thinner supply port 15.

FIG. 3 is an enlarged detail showing a part of the static pressure gas bearing device in the rotary atomizing electrostatic coating device. The bearing member 2 formed by using the porous member has an inner peripheral surface and both end surfaces such that the compressed gas is ejected from the inner peripheral surface and both end surfaces when compressed air is supplied from the outer peripheral surface. Further, gas ejection portions 2a, 2b, 2c are provided at and. In addition, the outer peripheral surface of the bearing member 2 is subjected to a crushing process at a portion except the circumferential groove at the central portion in the axial direction. And the rotating shaft 1
The bearing members 2 are fitted to the rotary shaft 1 on both sides of the flange portion 1F integrally formed with a larger diameter than the both sides at the axially intermediate portion of the rotary shaft 1. 1 is inserted and the bearing members 2 are arranged on both sides of the flange portion 1F.

In this state, the rotary shaft 1 and the bearing member 2 together with the synthetic resin housing body 5c of the synthetic resin cover 5 are provided.
Of the elastic member made of rubber or the like between each bearing member 2 and the inner diameter surface of the synthetic resin cover 5.
By interposing an elastic support member 16 such as a ring, the bearing member 2 is elastically supported by the inner diameter surface of the synthetic resin cover 5. Further, the left bearing member 2 is covered with a front cover 5b of a synthetic resin cover 5 on the outer end surface thereof which does not face the end surface of the flange portion 1F of the rotary shaft 1. As a result, a thrust bearing gap 17a having a predetermined size is formed between one end surface which is the inner end surface of each bearing member 2 and the end surface of the flange portion 1F of the rotary shaft 1 which faces the one end surface. Further, between the outer end surface (the other end surface) of each bearing member 2 and the synthetic resin cover 5 facing the other end surface, a damper clearance 17b, which is a predetermined clearance in the thrust direction.
Is formed.

Compressed gas is supplied to the outer peripheral surface of each bearing member 2 from the bearing air supply passage 11 formed in the synthetic resin cover 5, and is provided on the inner peripheral surface and both end surfaces of each bearing member 2. Compressed gas is ejected from the gas ejection portions 2a, 2b, 2c, and the inner peripheral surface of the gas is ejected from the gas ejection portion 2a between the inner peripheral surface of the bearing member 2 and the outer peripheral surface of the rotary shaft 1. A radial bearing gap 18 having a predetermined size is formed to support the rotating shaft 1 in the radial direction, and the pressure of the compressed gas ejected from the gas ejecting portion 2b on the inner end surface of each bearing member 2 is the flange portion 1F, that is, the rotating shaft. 1 is supported in the thrust direction. Further, each bearing member 2 itself is supported in the thrust direction in a non-contact manner with the synthetic resin front cover 5b and the synthetic resin housing main body 5c by the pressure of the compressed gas ejected from the gas ejection portion 2c on the outer end surface thereof. Has been done. The exhaust is performed through the air exhaust passage 13 formed in the synthetic resin cover 5 and the gap between the rotary shaft 1 and the front cover 5b.

Therefore, the radial load and moment of the rotating shaft 1 which is rotated at a high speed are determined by the gap between the two radial bearings 1.
8 is received by the gas pressure, and the thrust load of the rotary shaft 1 is received by the gas pressure in the thrust bearing gaps 17a on both sides of the flange portion 1F. As for the whirling of the rotary shaft 1 in the radial direction, the bearing member 2 is deformed in the radial direction with deformation of the elastic support member 16 such as an O-ring so that the radial bearing gap 18 becomes constant, as in the conventional case. It is absorbed by moving to. On the other hand, the deflection of the rotary shaft 1 in the thrust direction causes deformation of the elastic support member 16 such as an O-ring and the synthetic resin cover 5 and the bearing member 2 so that the thrust bearing gaps 17a on both sides of the flange portion 1F become constant. Is absorbed by the bearing member 2 moving in the thrust direction with a change in the thrust direction clearances 17b on both sides in the axial direction.
The thrust bearing gap 17a on both sides of the flange portion 1F and the thrust direction gap 17b on the synthetic resin cover 5 side are quickly damped by the gas pressure, and the flange portion 1F and the rotary shaft 1 are axially moved with respect to each bearing member 2. Keep in place. Therefore, the rotary shaft 1 and its flange portion 1F
Does not come into contact with each bearing member 2 in both the radial direction and the thrust direction.

That is, each bearing member 2 in the present embodiment has a structure in which it floats with respect to the synthetic resin cover 5 by the elastic support member 16 such as an O-ring having a damper function and the air film in the gap 17b in the thrust direction. .
Therefore, while the rotary shaft 1 and the bearing member 2 are required to be machined with high precision, the synthetic resin cover 5 that supports each bearing member 2 in a floating manner does not allow the conventional bearing member B to float. Even if the machining accuracy is rougher than that of the metal housing E, the function of the bearing is not impaired. Therefore, in this embodiment, the metal housing is omitted, and the bearing member 2 is directly held by the synthetic resin cover 5.

Next, the turbine mechanism 3 of this embodiment will be described in detail. The turbine mechanism 3 for rotating the rotary shaft 1 at a high speed is provided on the flange portion 1F of the rotary shaft 1. That is, the turbine blade 22 is provided on the outer peripheral portion of the flange portion 1F of the rotary shaft 1, and the outer circumferential surface of the flange portion 1F is provided with circumferential grooves 1F on both axial sides of the turbine blade 22.
c are respectively formed. The diameter of the circle connecting the radially outer ends of the turbine blades 22, that is, the outer diameter of the turbine blades 22 is larger than the inner diameter surface of the bearing member 2, and the turbine blades 22 are formed integrally with the rotary shaft 1. ing. When the turbine blade 22 has a large diameter, the output torque of the turbine mechanism 3 can be increased. Further, when the bearing members 2 are arranged on both sides of the turbine blade 22 in the axial direction, the torque of the turbine blade 22 can be received in a well-balanced manner, the rotation accuracy can be improved, and the rotation characteristics can be stabilized.

Further, on the inner peripheral surface of the synthetic resin cover 5,
A turbine nozzle 23 is provided for ejecting the compressed turbine air, which is supplied from the turbine air supply passage 12 passing through the synthetic resin cover 5, toward the turbine blades 22. When the compressed gas is jetted from the turbine nozzle 23 to the turbine blade 22, the turbine blade 22 is rotated by the pressure, and the rotary shaft 1 and thus the bell head 7 are rotated at high speed.

Next, the function and effect will be described. According to the rotary atomizing electrostatic coating device, the synthetic resin cover 5 holds the bearing member 2, so that the conventional metal housing E is used.
Is omitted, and the outer diameter of the rotary atomizing electrostatic coating device can be reduced, and the size and weight can be reduced. Therefore, it is possible to perform coating in a narrow space, which is conventionally done only by using a small spray gun, by the rotary atomizing electrostatic coating method that can obtain a beautiful and efficient coating surface. In addition, the number of parts can be reduced and the cost can be reduced. Further, conventionally, a bearing air supply passage for supplying compressed air to the bearing member 2 of the static pressure gas bearing and a turbine air supply passage for supplying compressed air to the turbine mechanism C are formed in the metal housing E. In addition, it is difficult to improve the productivity because the bearing member B must be precisely positioned in order to accurately position the bearing member B. However, by omitting the metal housing E, the production efficiency is improved.

In particular, when the static pressure gas bearing is constructed as shown in FIG. 3, each bearing member 2 is provided with respect to the synthetic resin cover 5 by the elastic supporting member 16 having a damper function and the air film in the thrust direction clearance 17b. Because it floats
The synthetic resin cover 5 itself supporting each bearing member 2 has a rougher processing accuracy than that of the structure without floating, so that the cost of the molding die is reduced, and the metal housing E is further omitted. A cost reduction effect can be obtained.

Moreover, as described above, in the radial whirling of the rotary shaft 1, the radial bearing gap 18 between the rotary shaft 1 and the bearing member 2 arranged on both axial sides of the turbine blade 22 is constant. Is absorbed by the radial movement of the bearing member 2 accompanied by the deformation of the elastic support member 16, and the deflection of the rotary shaft 1 in the thrust direction is kept constant in the thrust bearing gaps 17a on both sides of the flange portion 1F. As described above, the elastic support member 16 is deformed and the thrust direction gap 17b between the synthetic resin cover 5 and the bearing member 2 is changed, which is absorbed by the movement of the bearing member 2 in the thrust direction. Is rapidly attenuated by the gas pressure in the thrust bearing gap 17a and the thrust direction gap 17b on the synthetic resin cover 5 side. Since it is correctly maintained at a predetermined position in the axial direction with respect to 2, the torque of the turbine blades 22 is received in a well-balanced manner to ensure highly accurate rotation of the rotary shaft 1 and thus the bell head 7, and therefore the coating quality is deteriorated. Never.

In the above description of the embodiment, the case where the turbine mechanism 3 is provided on the flange portion 1F of the rotary shaft located in the middle of the pair of bearing members 2 and 2 arranged in the axial direction has been described. Not limited to this, the present invention can be applied even if the turbine mechanism 3 is provided at the rear end portion of the rotary shaft 1 within the synthetic resin cover 5 on the rear end side (right side in the drawing) of the bearing members 2 and 2. .

As the bearing member 2, not only the above-mentioned porous throttle bearing but also an orifice throttle bearing, a self-made throttle bearing, a surface throttle bearing and the like can be used.

[0024]

As described above, according to the rotary atomizing electrostatic coating apparatus of the present invention, since the synthetic resin cover holds the bearing member, the metal housing dedicated to holding the bearing member, which has been conventionally required. Can be omitted, and it is possible to provide a compact and lightweight rotary atomization electrostatic coating device with a reduced dimension in the direction perpendicular to the axis at low cost. As a result, it is possible to apply the rotary atomization electrostatic coating method, which has a high coating efficiency and can obtain a beautiful coating surface, even in a place where only a small spray gun can be used in the past.

In particular, when the bearing member for supporting the rotary shaft is made to float with respect to the synthetic resin housing, the synthetic resin housing has a rough processing accuracy, so that the cost is further reduced and the radial of the rotary shaft is reduced. Since the whirling in the direction and the whirling in the thrust direction are easily absorbed and dampened, high-precision rotation of the rotary shaft is ensured, and thus good coating quality is guaranteed.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing one cross section of a rotary atomizing electrostatic coating device of the present invention.

FIG. 2 is a configuration diagram showing another cross section of the rotary atomizing electrostatic coating device of the present invention.

FIG. 3 is a configuration diagram of an embodiment of a static pressure gas bearing device used in the rotary atomizing electrostatic coating device of the present invention.

FIG. 4 is a configuration diagram of a conventional rotary atomizing electrostatic coating device.

[Explanation of symbols]

 1 Rotating Shaft 2 Bearing Member 3 Turbine Mechanism 5 Synthetic Resin Cover 6a Paint Supply Pipe 6b Thinner Supply Pipe 8 High Voltage Generator 16 Elastic Support Member 17a Thrust Bearing Gap 17b Thrust Direction Gap 18 Radial Bearing Gap

Claims (1)

[Claims] 1. A rotary atomizing electrostatic coating device in which a rotary shaft is supported by a bearing member, the bearing member is held by a synthetic resin cover, and a high voltage generator is embedded in the synthetic resin cover.