JPH04334565A - Rotary atomization head-type electrostatic coating device - Google Patents

Abstract

PURPOSE:To prevent the occurrence of a sputtering phenomenon between an air motor and its rotating shaft by applying a high voltage to the rotating shaft through a feed tube and an anti-sputtering brush. CONSTITUTION:An anti-sputtering brush 43 is provided on a paint nozzle 41. Then the paint nozzle 41 is installed on the device 27 of a feed tube 26 and a rotating shaft 15 is electrically connected to the sleeve 27 through the brush 43.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a center-feed rotary atomizing head type electrostatic coating device that supplies paint through a rotating shaft.

0002

[Prior Art] In general, a center-feed type electrostatic coating device using a bell-shaped or disk-shaped rotating atomizing head rotates the rotating atomizing head at high speed and paints the paint through a feed tube provided within the rotating shaft. By supplying the charged paint to the rotating atomizing head, the paint is atomized, and the atomized charged paint particles fly and adhere to the object to be coated along the lines of electric force.

[0003] A conventional center-feed type electrostatic coating apparatus will now be described with reference to FIGS. 3 and 4.

First, in FIG. 3, 1 is an electrostatic coating machine, and 2 is an electrostatic coating machine.
1 is a main body made of a resin material (for example, polyacetal) that forms the housing of the electrostatic coating machine 1. The front end of the main body 2 is an annular motor holder 2A, and the rear end has a mounting bracket (not shown). ) is provided.

Reference numeral 3 designates a turbine-type air motor provided in the motor holder portion 2A of the main body 2. is drilled in
A radially circular turbine chamber 5A located on one side in the axial direction
However, there is a shaft hole 5 in which a large diameter hole 5B is formed near the middle part, and radial air bearings 6, 6 located in the large diameter hole 5B of the shaft hole 5 and disposed in the motor housing 4. , thrust air bearings 7, 7 provided in the axial direction front and rear of the turbine chamber 5A in the shaft hole 5, and located between the thrust air bearings 7, and a large number of blades (not shown) on the outer peripheral surface. ) and turbines 8 arranged at equal intervals.

Each of the radial air bearings 6 is positioned around the rotating shaft 15 and fixed to the motor housing 4 in order to support the rotating shaft 15, which will be described later, in a non-contact state with respect to the shaft hole 5. The motor housing 4 comprises a sleeve-shaped bearing 9 made of a breathable metal material, and an air chamber 10 located on the outer peripheral surface of the bearing 9 and formed concentrically with the shaft hole 5 in the motor housing 4. Each of the air bearings 6 constitutes a static pressure air bearing by the bearing 9 and the air chamber 10, and as will be described later, the high pressure air supplied to the air chamber 10 is blown out from the bearing 9, so that the rotating shaft 15 is Can be supported in contact. Although it has been described that two radial air bearings 6 are arranged at a predetermined interval in the axial direction,
The number of air bearings 6 may be one, or three or more may be provided.

Each of the thrust air bearings 7 is disposed in the motor housing 4 on both sides of the turbine 8 in order to support the turbine 8 in a non-contact manner with respect to the turbine chamber 5A. An annular bearing 11 made of a breathable metal material is fixed to the motor housing 4 so as to sandwich both sides of the bearing 11, and an air chamber 12 formed in the motor housing 4 and located on the back side of the bearing 11. configured. Each of the air bearings 7 also includes a bearing 11 and an air chamber 12.
The turbine 8 can be supported in a non-contact manner by forming a static pressure bearing, and by jetting the high pressure air supplied to the air chamber 12 to the bearing 11.

Reference numeral 13 indicates a turbine driving air passage formed in the main body 2 and the motor housing 4. One end of the turbine driving air passage 13 is connected to an air source (not shown), and the other end is connected to the turbine chamber 5A. Inside the turbine 8
The nozzle opening opens toward the front of the blade. The high-pressure air supplied to the turbine drive air passage 13 is injected onto the blades of the turbine 8, thereby causing the turbine 8 to rotate at a high speed.

Reference numeral 14 indicates a bearing air passage formed in the main body 2 and the motor housing 4. One end of the air passage 14 is connected to a pressure source (not shown), and the other end 14A,
14A, . . . are branched and connected to each air chamber 10, 12, respectively.

Reference numeral 15 indicates a rotary shaft formed into a hollow cylinder shape made of a metal material and inserted into the shaft hole 5 of the air motor 3. A turbine 8 is fixed to the base end side of the rotary shaft 15, and a tip portion 15A is attached to the rotary shaft 15. protrudes outside the air motor 3, and the intermediate portion is supported statically by each radial air bearing 6 in a non-contact state with a minute gap between the motor housing 4 and the motor housing 4.

Reference numeral 16 indicates a bell-shaped rotating atomizing head located outside the air motor 3 and fixed to the tip 15A of the rotating shaft 15, and the rotating atomizing head 16 is arranged with an axially intermediate rim 16A in between. One end side becomes the attachment part 16B attached to the tip side of the rotating shaft 15, and the other side becomes the smooth surface 16 that expands into a morning glory shape.
C, and the tip of the smoothed surface 16C is a discharge edge 16D in which a large number of V-shaped grooves are formed. A hub member 17 is attached to the rotary atomizing head 16 in the middle of the smoothing surface 16C, and the rear side of the hub member 17 receives paint and cleaning solvent from a feed tube 26 (described later) through a paint nozzle 30. Convex conical paint supply surface 1 where etc. are supplied.
7A, a large number of first hub holes 17B are bored in the peripheral part to supply paint and cleaning solvent from the paint supply surface 17A to the discharge edge 16D side, and a hub front face 17C is bored in the center part.
A second hub hole 17D that supplies cleaning solvent when cleaning the
, 17D, . . . are drilled.

Reference numeral 18 denotes a first shaping air nozzle provided on the tip side of the main body 2 so as to surround the outer periphery of the rotary atomizing head 16; 19, the first shaping air nozzle 18;
The second shaping air nozzle 19 is screwed and fixed to a main body cover 20 that covers the main body 2 and the air motor 3, and the first shaping air nozzle 18 is connected to the air motor 3. It is caught between. Furthermore, the shaping air nozzles 18 and 19 and the main body cover 20 are made of an insulating material (for example, polyacetal).

[0013] Here, the air motor 3 and the main body cover 2
A first shaping air chamber 21 is formed between the main body 2 and the main body 2, and shaping air is supplied to the air chamber 21 through a shaping air supply passage (not shown) formed in the main body 2. There is. Further, a second shaping air chamber 22 is formed between the first and second shaping air nozzles 18 and 19, and a second shaping air chamber 22 is formed between the first and second shaping air nozzles 18 and 19.
The second shaping air chambers 21 and 22 communicate with each other via a shaping air passage 23 formed in the first shaping air nozzle 18. The shaping air in the second shaping air chamber 22 is then flowed from the ring-shaped air jet holes 24 formed at the tips of the first and second shaping air nozzles 18 and 19 to the tip side of the rotary atomizing head 16. The coating pattern sprayed onto the outer periphery from the rotary atomizing head 16 is formed into a circular pattern.

A ring-shaped air jet hole 25 is also formed between the outer circumferential surface on the tip side of the rotary atomizing head 16 and the tip of the first shaping air nozzle 18, and air flows out from each air bearing 6, 7, turbine 8, etc. A part of the air is ejected as shaping air.

Reference numeral 26 denotes a feed tube provided coaxially within the rotating shaft 15. The feed tube 26 consists of an outer cylinder 27 and an inner cylinder 28, and the proximal end of the outer cylinder 27 has a ring 39 and a ring 39, which will be described later. It is attached to the main body 2 via a holding member 40, and the tip side is a nozzle attachment part 27A to which a paint nozzle 30, which will be described later, is attached. Further, the proximal end side of the inner cylinder 28 is attached to the main body 2 via the holding member 40, and the distal end side extends near the nozzle attachment part 27A of the outer cylinder 27, and the inner cylinder 28 and the outer cylinder 27 are connected to each other. A communication part 29 that communicates between
It becomes.

30 is a nozzle mounting portion 27A of the outer cylinder 27.
As shown in FIG.
0A, and a small diameter portion 30 formed on the tip side of the cylindrical portion 30A.
B, a discharge portion 30C formed in a tapered shape on the distal end surface of the small diameter portion 30B, a valve seat 30D formed on the base end surface on which a valve body 34C of a paint supply valve 34 to be described later is seated, and the cylindrical portion. A threaded portion 30E formed on the outer peripheral surface of the cylinder portion 30A, and an O-ring groove portion 30F located between the threaded portion 30E and the valve seat 30D, into which the O-ring 31 formed annularly on the outer peripheral surface of the cylindrical portion 30A is mounted. It is composed of. Further, the inner peripheral surface of the paint nozzle 30 serves as a paint discharge passage 30G.

Reference numeral 32 indicates a paint supply passage formed in the inner cylinder 28, and the paint supply passage 32 is connected to a paint discharge passage 30G of a paint nozzle 30 provided in the outer cylinder 27 and a paint supply valve 34 to be described later. It is connected so that it can be opened and closed. Reference numeral 33 indicates a paint discharge passage formed between the outer cylinder 27 and the inner cylinder 28, and the paint discharge passage 33 and the paint supply passage 32 communicate with each other at a communicating portion 29. In addition, paint supply passage 3
2 is connected to a color changing device (not shown), and a paint discharge passage 3
3 is connected to a drainage tank (not shown).

Reference numeral 34 indicates a paint supply valve consisting of a 2-port, 2-position spring return type air switching valve. The actuator 34A
It consists of a valve shaft 34B that moves forward and backward, and a valve body 34C that is provided at the tip of the valve shaft 34B and seats on and off the valve seat 30D of the paint nozzle 30. Open and close. 35 is also 2 ports 2
The drain valve 35 also includes an actuator 35A provided in the main body 2, a valve shaft 35B, and a valve body 35C that opens and closes the middle of the paint discharge passage 33. It consists of

Reference numeral 36 indicates an annular conductive ring attached to the outer peripheral surface of the air motor 3. The conductive ring 36 is connected to a high voltage cable (not shown) via a connecting member 37 and a high voltage resistor 38. The high voltage cable is connected to an external high voltage generator (not shown).

Reference numerals 39 and 40 indicate metal rings and holding members provided between the main body 2 and the air motor 3, and the ring 39 electrically connects the motor housing 4 of the air motor 3 and the outer cylinder 27 of the feed tube 26. The holding member 40 is connected to the outer cylinder 27 and the inner cylinder 28 of the feed tube 26.
The motor housing 4 and the inner cylinder 28 are electrically connected to each other via a ring 39.

The high voltage from the high voltage generator is then applied to the motor housing 4 of the air motor 3 via the high voltage cable, high voltage resistor 38, connecting member 37 and conductive ring 36.
It is also supplied to the feed tube 26 via the ring 39 and the holding member 40.

[0022] The prior art is constructed as described above, and the coating process thereof will be described next.

First, in the painting preparation step, it is assumed that the color changing device is driven and the paint supply passage 32 is filled with paint. A high voltage is then applied from the high voltage generator to the feed tube 26 via the high voltage cable, high resistance 37, connection member 37, conductive ring 36, and the motor housing 4, ring 39, and holding member 40 of the air motor 3. supply. Further, shaping air is supplied from the shaping air supply passage, and is ejected from the ring-shaped air ejection hole 24 via the first shaping air chamber 21, the shaping air passage 23, and the second shaping air chamber 22. . In this state, a painting air control signal is supplied to the actuator 34A of the paint supply valve 34, and the valve body 34C is displaced to the right in the figure together with the valve shaft 34B to open the valve.

As a result, the paint in the paint supply passage 32 is transferred from the paint discharge passage 30G of the paint nozzle 30 to the rotary atomizing head 16.
The paint is discharged toward the paint supply surface 17A of the hub member 17 provided at the hub member 17. Due to the high speed rotation of the rotary atomizing head 16, the discharged paint passes through the first hub hole 17B and reaches the smoothed surface 16.
C flows toward the discharge edge 16D, is sprayed as a liquid thread from the discharge edge 16D, and is electrostatically atomized to become charged particles. These charged particles fly along the lines of electric force between the rotary atomizing head 16 and the object to be coated, and are applied to the object to be coated.

At this time, since a high voltage is applied to the feed tube 26, the paint is charged while passing through the paint supply passage 32, and when this charged paint is atomized from the rotary atomizing head 16. The particles become charged particles, which improves the efficiency of coating onto objects.

[0026]

[Problems to be Solved by the Invention] In the above-mentioned prior art, the paint is charged by applying a high voltage to the feed tube 26; The high voltage applied is not only applied to the feed tube 26 but also supplied to the motor housing 4 of the air motor 3.
The motor housing 4 also becomes in a high voltage state. On the other hand, since paint charged to a high voltage is continuously ejected to the rotating atomizing head 16 while passing through the feed tube 26, the rotating atomizing head 16 and the rotating shaft 15 also have a high voltage. However, the rotating shaft 15 and the rotating atomizing head 16 each have air bearings 6,
Since the feed tube 26 and the motor housing 4, which are charged at a high voltage, are not in direct contact with each other, the feed tube 26 and the motor housing 4, which are charged at a high voltage, are not in direct contact with each other. For this reason, since an air chamber consisting of a minute gap exists between the rotating shaft 15, the shaft hole 5, and each bearing 9, 11, a sputtering phenomenon occurs due to an abnormal voltage difference therebetween.

As a result, due to this sputtering phenomenon, the metal of the inner peripheral surface of the shaft hole 5 and each of the bearings 9, 11 is ionized and deposited on the outer peripheral surface of the rotating shaft 15, and the deposits S, S are formed as shown in FIG. ,... occurs. As a result, each vapor deposit S grows in the radial direction of the rotating shaft 15, and the rotating shaft 15 comes into contact with each bearing 9, 11 and the shaft hole 5, and the rotating shaft 15 comes into contact with each bearing 9, 11 and the shaft hole 5.
5, resulting in rotational resistance of the rotary atomizing head 16, reducing the rotation speed of the rotary atomizing head 16, reducing the atomization efficiency of the paint, reducing the coating efficiency, and shortening the life of the rotary atomizing head type electrostatic coating device. There is a problem with doing so.

The present invention has been made in view of the problems of the prior art described above, and provides a rotary atomizing head type electrostatic coating device that can be used for a long period of time without reducing coating efficiency. The purpose is to

[0029]

[Means for Solving the Problems] A feature of the configuration adopted by the present invention in order to solve the above-mentioned problems is that a high voltage is applied to either the feed tube or the rotating shaft from the feed tube to the rotating shaft. The reason is that a sputtering prevention brush is provided to prevent sputtering.

[0030]

[Operation] With the above configuration, high voltage can be supplied from the feed tube to the rotating shaft, and sputtering between the rotating shaft and the air motor can be prevented.

[0031]

Embodiments Hereinafter, embodiments of the present invention will be described with reference to FIGS. 1 and 2. In the embodiment, the same components as those in the prior art described above are given the same reference numerals, and their explanations will be omitted.

In the figure, reference numeral 41 indicates the nozzle mounting portion 27 of the outer cylinder 27.
The paint nozzle 41 of this embodiment is shown in FIG. portion 41A, a small diameter portion 41B formed on the distal end side of the cylindrical portion 41A, a discharge portion 41C formed in a tapered shape on the distal end surface of the small diameter portion 41B, and a valve body 34C of the paint supply valve 34 on the base end surface. a valve seat 41D formed to be seated; a threaded portion 41E formed on the outer peripheral surface of the cylindrical portion 41A;
1A, and an O-ring groove 41F into which an annularly formed O-ring 42 is attached. Further, the inner peripheral surface of the paint nozzle 41 becomes a paint discharge passage 41G,
A small hole 41H is formed in the cylindrical portion 41A located between the small diameter portion 41B and the threaded portion 41E.

Reference numeral 43 indicates a sputtering prevention brush, and the sputtering prevention brush 43 is made of several dozen pieces of highly flexible fibrous conductive material (for example, carbon fiber), and its base end is connected to the paint nozzle 41. Small hole 41H
The distal end side extends so as to diffuse into the paint nozzle 41 in the radial direction. Here, after the sputtering prevention brush 43 is inserted into the small hole 41H, it is fixed by hitting the periphery of the small hole 41H with a punch, and 44, 44, . . . are dents from the punch. It is.

[0034] And sputtering prevention brush 43
By providing the paint nozzle 41 equipped with a paint nozzle 41 in the nozzle attachment part 27A of the outer cylinder 27 of the feed tube 26, the tip side of the sputtering prevention brush 43 comes into contact with the rotating shaft 15, so that the paint is supplied to the outer cylinder 27 of the feed tube 26. The resulting high voltage is applied to the rotating shaft 15 via the sputtering prevention brush 43. Therefore, even when the rotary shaft 15 is rotated by the air motor 3, the sputtering prevention brush 43 does not become a rotational resistance of the rotary shaft 15, but always contacts the rotary shaft 15, and applies a high voltage to the rotary shaft 15. continuing.

The electrostatic coating apparatus according to this embodiment has the above-described configuration, and its basic operation is not particularly different from that of the prior art.

Thus, according to the present embodiment, by providing the paint nozzle 41 having the sputtering prevention brush 43 in the nozzle attachment portion 27A of the outer cylinder 27 of the feed tube 26, the paint is supplied to the outer cylinder 27 of the feed tube 26. The high voltage can be applied to the rotating shaft 15 via the sputtering prevention brush 43, and the high voltage can be easily applied to the rotating shaft 15.

As a result, the potential difference between the rotating shaft 15, the motor housing 4 of the air motor 3, and each bearing 9, 11 is eliminated, and the same potential is generated between the rotating shaft 15, the shaft hole 5, and each bearing 9, 11. It is possible to reliably prevent the sputtering phenomenon. As a result, it is possible to effectively prevent the deposition S from occurring on the outer circumferential surface of the rotating shaft 15 due to the sputtering phenomenon.
rotating shaft 1 for a long period of time without reducing the rotational resistance of
5 can be rotated as high as rated. This prevents a decrease in the rotational speed of the rotary atomizing head 16, keeps the atomization efficiency constant, and prevents the coating efficiency from decreasing. Therefore, the life of the electrostatic coating device can be effectively extended.

In the above embodiment, the sputtering prevention brush 43 is provided on the paint nozzle 41, but in the present invention, instead of this, the sputtering prevention brush 43 is provided on the inner peripheral surface of the rotating shaft 15. Moreover, the shape of the sputtering prevention brush 43 is not limited to the fibrous shape, and may be any shape as long as it does not cause rotational resistance to the rotating shaft 15.

The feed tube 26 also has an outer cylinder 27,
Although a double cylindrical tube consisting of an inner tube 28 is shown as an example, a tube using a single feed tube may also be used, as shown in, for example, Japanese Utility Model Publication No. 1-41496.

Further, although the paint nozzle 41 is attached to the feed tube 26 as an example, when the paint valve is provided in the middle of the paint supply passage, the feed tube is made into a single cylindrical body, and the paint nozzle In this case, a sputtering prevention brush may be provided at the tip of the feed tube.

[0041]

As detailed above, according to the present invention, either the feed tube or the rotating shaft is provided with a sputtering prevention brush that applies a high voltage from the feed tube to the rotating shaft. Therefore, high voltage can be easily applied from the feed tube to the rotating shaft, and the sputtering phenomenon that conventionally occurs between the air motor and the rotating shaft can be reliably prevented. It is possible to effectively prevent the occurrence of vapor deposits, and maintain the rotational speed of the rotating shaft at the rated rotational speed for a long period of time.

[Brief explanation of drawings]

FIG. 1 is a longitudinal cross-sectional view of a main part of an electrostatic coating machine showing an embodiment of the present invention.

FIG. 2 is a perspective view showing a paint nozzle and a sputtering prevention brush according to the present invention.

FIG. 3 is a vertical cross-sectional view of main parts of an electrostatic coating machine according to the prior art.

FIG. 4 is a perspective view of a paint nozzle according to the prior art.

[Explanation of symbols]

1 Electrostatic coating machine 3 Air motor 5 Shaft hole 6 Radial air bearing 7 Thrust air bearing 8 Turbine 15 Rotation axis 16 Rotating atomization head 26 Feed tube 27 Outer cylinder 28 Inner cylinder 41 Paint nozzle 43 Sputtering prevention brush

Claims (1)

[Claims] Claim 1: An air motor having a shaft hole bored in the axial direction, a radial air bearing provided around the shaft hole, and a turbine supported by a thrust air bearing deep inside the shaft hole. , is inserted into the shaft hole of the air motor, is supported by the air bearing, has one axial end fixed to the turbine, and the other end protrudes outside the air motor, and is rotated by the turbine in a non-contact state with respect to the air motor. A rotating shaft, a rotating atomizing head provided at the other end of the rotating shaft, and a rotary atomizing head that is coaxially inserted into the rotating shaft, one end connected to the paint source, and the other end extending into the rotating atomizing head. A rotary atomizing head-type electrostatic coating device comprising a feed tube for applying a high voltage to the feed tube and a high voltage applying means for applying a high voltage to the feed tube via the air motor, wherein either the feed tube or the rotating shaft has a A rotary atomizing head type electrostatic coating device, characterized in that it is provided with a sputtering prevention brush that applies a high voltage from the feed tube to the rotating shaft.