JPS59228959A - Rotary atomization electrostatic painting device - Google Patents

Abstract

PURPOSE:To extend the life of an electrode by forming the electrode into a pin shape consisting of a metallic material and pressing the tip thereof to the rear end of a revolving shaft by means of a spring. CONSTITUTION:An electrode 6 inserted slidably into a cylindrical hole 65 in an electrode holder 63 consists of a metallic material such as gun metal softer than the material of a revolving shaft 8 and is formed integrally with a small-diameter pin part 66a and an expanding head part 66b. The tip of the pin part 66a is pressed onto the end face of the revolving shaft part 8c by the spring force of a compression spring 68. The pointed tip of such metallic electrode 66 is brought into contact with the rear end face of the shaft 8 on the axial line of revolution of the shaft 8, by which the wear of the electrode 66 is considerably reduced and since the electrode 66 is cooled by the air past a turbine wheel 42, tbe deterioration of the electrode 66 is suppressed.

Description

[Detailed description of the invention] Industrial applications The present invention relates to a rotary atomization electrostatic coating apparatus.

Conventional rotary atomizing electrostatic coating equipment has a rotating shaft supported in a non-contact manner by a non-contact radial bearing and a non-contact thrust bearing in a housing, and a cup-shaped spray head is attached to the outer end of the rotating shaft. A rotary atomizing electrostatic coating device is known which is fixed and equipped with a paint supply device for supplying paint onto the inner circumferential surface of a spray head and a rotary shaft rotation drive device. In this rotary atomizing electrostatic coating device, it is necessary to apply a negative high voltage to the spray head, but as mentioned above, the rotating shaft is supported by the housing in a non-contact manner, so the negative high voltage is applied to the housing. Even if it is applied, it is not possible to apply a negative high voltage to the spray head. Therefore, in this rotary atomization electrostatic coating device, an electrode made of carbon is mounted on the housing facing the rear end of the rotary shaft, and this electrode is pressed onto the rear end of the rotary shaft to electrically connect the housing and the rotary shaft. , thereby applying a negative high voltage to the spray head.

However, when the electrodes are made of carbon in this manner, the electrodes are subject to severe wear, and carbon powder scatters around the rotary shaft, contaminating the rotary shaft and the turbine wheel attached to the rotary shaft.

OBJECTS OF THE INVENTION It is an object of the present invention to provide a rotary atomization electrostatic coating device which increases the life of the electrodes and prevents them from being contaminated by carbon.

Structure of the Invention The structure of the present invention includes a rotating shaft supported in a non-contact manner by a non-contact radial bearing and a non-contact thrust bearing in a housing of a rotary atomizing electrostatic coating device, and the outer end of the rotating shaft is The cup-shaped spray head is fixed to the housing, and is equipped with a paint supply device and a rotary shaft rotation drive device for supplying paint onto the inner peripheral surface of the spray head, and the inner end of the rotary shaft is electrically connected to the housing. In the rotary atomizing electrostatic coating device, a bottle-shaped electrode made of a metal material was attached with acid on the housing facing the rear end of the rotating shaft, and the tip of the electrode was pressed against the rear end of the rotating shaft by a spring. be.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to FIG. 1, a rotary atomizing electrostatic coating apparatus, generally designated 1, comprises a substantially hollow cylindrical metal front housing 2 and a substantially hollow cylindrical rear metal housing 3. , these two housings 2.3 are firmly connected by bolts 4. A support rod 6 made of an electrically insulating material is fitted into the cylindrical hole 5 of the rear housing 3, and the rear housing 3 is secured to the support rod 6 with bolts 7.

This support rod 6 is supported by a base (not shown). On the other hand, a rotating shaft 8 is inserted into the front housing 2. This rotating shaft 8 has a hollow cylindrical part 8a located in the center thereof, a shaft part 8b integrally formed at the front end of the hollow cylindrical part 8a, and a shaft part 8c fixed to the rear end of the hollow cylindrical part 8a. A metal spray head 9 is fixed to the shaft portion 8b of the rotating shaft 8 with a nut 10. The spray head 9 is composed of a p]N head support 12 having an annular space 11 formed therein, and a cup-shaped spray NB main body 13 fixed on the support 12. Figure 1 and 2
As shown in the figure, the outer cylindrical portion 14 of the support body 12 has an opening into the annular space 11 and a spray pipe. A large number of paint outflow holes 16 are formed that smoothly connect to the inner wall surface 15 of the 8-body construction 3.

On the other hand, an end plate 17 is fixed to the front end of the front housing 2, and a paint spray nozzle 18 is mounted on this end plate 17. The paint injection nozzle 18 is connected to a paint tank 20 via a paint supply pump 19, and the paint injection nozzle 1
The nozzle opening 21 of No. 8 is directed toward the cylindrical inner circumferential wall surface of the support outer cylinder 14 .

As shown in FIG. 1, a pair of radial air bearings 30' and 31 are disposed within the front housing 2, and the rotating shaft 8 is rotatably supported by these radial air bearings 30 and 31 in a non-contact manner. . Each radial air bearing 30,3
1 has annular air introduction chambers 32 and 33 formed therein, respectively, and on the inner peripheral surface of each radial air bearing 30 and 31 there are a number of air jet holes 34 connected to the annular air introduction chambers 32 and 33, respectively. 35 is formed. The air introduction hole 36 of the annular air introduction chamber 32 and the air introduction hole 37 of the annular air introduction chamber 33 are connected to an air supply pump 38.

On the other hand, as shown in FIG. 1, a pair of disc-shaped runners 39 and 40 are inserted into the shaft portion 8c of the rotating shaft 8, and these runners 39 and 40 are connected to each other by a nut 43 via a spacer 41 and a turbine wheel 42. It is fixed to the shaft portion 8C. On the other hand, an annular plate 44 is disposed between the runners 39 and 40, and the runners 39 and 40 and the annular plate 44 constitute a non-contact type thrust air bearing. Note that each runner 39 and 40 is arranged so as to be separated from the annular plate 44 by a slight gap. The annular plate 44 has a pair of O-rings 45, 4
6 to the front housing 2 in a sealing manner. As shown in FIGS. 1 and 3, an annular groove 47 is formed in the front housing 2 along the outer circumferential surface of an annular plate 44, and this annular groove 47 is used for compressed air formed in the front housing 2. It is connected to an air supply pump 49 via an introduction hole 48 . On the other hand, a large number of air passages 50 are formed in the annular plate 44 and extend radially inward from the annular groove 47, and a runner 39 is formed from the vicinity of the inner end of each air passage 50.
and an air outlet hole 51' extending toward the runner 40;
52 is formed.

On the other hand, a turbine nozzle holder 53 is fixed within the front housing 2 adjacent to the annular plate 44, and an annular air introduction chamber 54 is formed between the turbine nozzle holder 53 and the front housing 2. This air introduction chamber 54 is connected to a compressor 56 via a compressed air introduction hole 55. The air introduction chamber 54 has a compressed air jet nozzle 57 equipped with a large number of guide vanes (not shown), and the turbine blades 58 of the turbine wheel 42 are disposed facing the jet nozzle 57 . Meanwhile, the housing interior chamber 59 in which the turbine impeller 42 is disposed is connected to the atmosphere through an exhaust hole 60 formed in the rear housing 3. compressor 56
The compressed air introduced into the air introduction chamber 54 is ejected into the housing internal chamber 59 through the ejection nozzle 57. At this time, the jetted compressed air applies rotational force to the turbine wheel 42, and the rotating shaft 8 is thus rotated at a high speed. This jetted compressed air is then exhausted to the atmosphere through the exhaust hole 60.

On the other hand, a through hole 62 is formed in the end wall 61 of the rear housing 3 that defines the housing internal chamber 59 , and an electrode holder 63 passing through the through hole 62 is fixed to the end wall 61 . A cylindrical hole 65 is formed coaxially with the rotation axis of the rotation shaft 8 inside the electrode holder 63, and a material softer than the material of the rotation shaft 8, such as gunmetal, is formed inside the cylindrical hole 65. An electrode 66 made of a metal material is slidably inserted therein. This electrode 66 consists of a small diameter pin portion 66a and an enlarged head portion 66b, and these pin portion 66a and enlarged head portion 66b are integrally formed. The tip portion of the pin portion 68a is formed into a pointed shape, and the tip portion of the pin portion 68a is formed into a pointed shape, and the tip portion of the pin portion 68a is
Contact on the end face of C. An adjustment screw 67 is fixed to the rear end of the cylindrical hole 65 of the electrode holder 63, and a compression spring 68 is inserted between the enlarged head 66b of the electrode 66 and the adjustment screw 67. The tip of the electrode 66 is pressed onto the end surface of the rotating shaft portion 8C by the spring force of the compression spring 68.

On the other hand, a terminal 69 is fixed on the outer wall surface of the rear housing 3 with a bolt 70, and this terminal 69 is connected to a high voltage generator 71 for generating a negative high voltage of -60 kV to -190 kV. Therefore, a high negative voltage is applied to the front housing 2 and the rear housing 3, and a high negative voltage is also applied to the spray head 9 via the electrode 66 and the rotating shaft 8.

From the nozzle port 21 of the paint injection nozzle 18 to the support outer cylinder 14
The paint sprayed onto the inner peripheral wall surface of the spray head body 13 flows out onto the inner peripheral wall surface 15 of the spray head main body 13 through the paint outlet hole 16 due to the centrifugal force generated by the rotation of the spray head 9. Next, this paint spreads as a thin liquid film on the inner circumferential wall surface 15 and reaches the end portion 13a of the main rod body 13. As mentioned above, a negative high voltage is applied to the spray head 9, and therefore the centrifugal force generated by the rotation of the spray head 9 causes the spray head main body 1 to
The paint that spreads in a thin film form from the tip 13a of 3 becomes a spray charged with a negative high voltage. Normally, the surface to be painted is at zero potential, so the paint spray is attracted toward the surface by electric force, thereby painting the surface.

As described above, the rotating shaft 8 is supported by a thrust air bearing consisting of runners 39 and 40 and an annular plate 44, and a pair of radial static air bearings 30 and 31.

In the radial static pressure air bearings 30 and 31, the air jet holes 34
The bearings 30 and 31 are
An air layer is formed between the inner peripheral surface of the rotating shaft hollow cylindrical portion 8a and the outer peripheral surface of the rotating shaft hollow cylindrical portion 8a, and the rotating shaft 8 is supported by this air layer in a non-contact state. On the other hand, in the above-mentioned thrust bearing, the compressed air introduced into the annular groove 47 from the air supply pump 49 passes through the air passage 50 and from the air outlet holes 51 and 52 to the annular plate 4.
4 and the runners 39 and 40, and the pressure necessary to maintain the minute gap between the annular plate 44 and the runners 39 and 40 is generated within this gap. Therefore, the rotating shaft 8 is supported by a pair of radial bearings and a thrust bearing in a non-contact manner with a small air layer interposed therebetween. As is well known, the viscosity coefficient of air is approximately one tenth of the viscosity coefficient of lubricating oil. Therefore, air bearings that use air as a lubricant have extremely small friction losses, and the amount of heat generated by friction losses is extremely small, making it possible to rotate at considerably high speeds. In the embodiment shown in FIG. 1, the rotating shaft 8 is 8000 Or, p
, m can be rotated at high speeds.

Effects of the Invention By forming the electrode 66 from a metal material and bringing the pointed tip of the electrode 66 into contact with the rear end surface of the rotating shaft 8 on the axis of rotation of the rotating shaft 80, wear of the electrode 66 can be greatly reduced. can be reduced.

Furthermore, since the electrode 66 is made of a metal material, carbon does not fly away as in the conventional case, and therefore there is a risk that carbon will adhere to the turbine blades 58 of the turbine wheel 42 and reduce the rotational performance of the air turbine. There is no.

In addition, the electrode 6 is caused by the air that has passed through the turbine wheel 42.
Since the electrode 66 is cooled, deterioration of the electrode 66 can be suppressed.

[Brief explanation of drawings]

FIG. 1 is a side cross-sectional view of a rotary atomization electrostatic coating apparatus according to the present invention, FIG. 2 is a cross-sectional view taken along line nn in FIG. 1, and FIG. It is a sectional view taken along one line. 2.3...Housing, 8...Rotating shaft, 9...Spray mHM, 18...Paint spray nozzle, 30, 31...
・Radial air bearing, 39, 40...Runner, 44
... Annular plate, 66... Electrode.

Claims (1)

[Claims] The rotary atomizing electrostatic coating device is equipped with a rotating shaft supported in a non-contact state by a non-contact radial bearing and a non-contact thrust bearing in the housing, and a cup-shaped injection head is provided at the outer end of the rotating shaft. A rotary atomizer, which is fixed and is equipped with a paint supply device for supplying paint onto the inner circumferential surface of the spray head and the rotary shaft rotation drive device, and the inner end of the rotary shaft is electrically connected to the housing. In an electrostatic coating device, a pin-shaped electrode made of a metal material is mounted on the housing facing the rear end of the rotating shaft, and the tip of the electrode is pressed against the rear end of the rotating shaft by a spring. Painting equipment.