JP2003236417A - Rotary atomizing head type coating apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a rotary atomizing head type coating apparatus capable of certainly charging the particles of a coating material and capable of feeding charged particles to an article to be coated to enhance coating efficiency. <P>SOLUTION: An electrode rod 20 is protruded so that the leading end thereof is protruded to the front of a rotary atomizing head 14 and four branched external electrodes 22, which are branched toward the front region of the rotary atomizing head 14, are provided to the leading end of the electrode rod 20. By this constitution, the branched external electrodes 22 form an ionizing region B in front of the rotary atomizing head 14 over the range from the axial center side of the rotary atomizing head 14 to the outer peripheral side thereof and, therefore, the particles of the coating material passing through a wide range from the axial center side of the rotary atomizing head 14 to the outer peripheral side thereof are charged with high voltage. Further, the distance dimension L1 between the leading end of each of the branched external electrodes 22 and the coating discharge end edge 14D of the rotary atomizing head 14 is made almost equal to the distance dimension L2 between the leading end of each of the branched external electrodes 22 and the article T to be coated to enhance the electric field intensity between the branched external electrodes 22 and the article T to be coated. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to, for example, a water-based paint,
The present invention relates to a rotary atomizing head type coating device by an indirect charging method, which is suitable for coating with a solvent-based paint.

[0002]

2. Description of the Related Art Generally, as a rotary atomizing head type coating apparatus, a high voltage is applied to the rotary atomizing head to directly charge the paint passing through the rotary atomizing head to a high voltage. A head type coating device, for example, an external electrode is provided on the outer peripheral side of the rotary atomizing head, and a corona discharge region is formed on the outer peripheral side of the rotary atomizing head by the external electrode, thereby forming an ionization zone region by the corona discharge region. An indirect charging type rotary atomizing head type coating device is known in which the paint particles are charged to a high voltage when the paint particles pass through.

Of these coating apparatuses, a rotary atomizing head type coating apparatus by an indirect charging system will be described with reference to FIGS. 6 and 7.

In the figure, reference numeral 1 is a cover which is the outer shape of a rotary atomizing head type coating apparatus, and the cover 1 is formed into a thin cylindrical shape by using, for example, an insulating resin material, and an air motor 2 described later therein. Are housed.

Reference numeral 2 is an air motor housed in a cover 1. The air motor 2 is a motor body 2 formed in a cylindrical shape.
A and an air turbine 2 housed in the motor body 2A
B, and a static pressure air bearing 2C that rotatably supports a rotating shaft 3 described later. The air motor 2 is driven to rotate by supplying high-pressure air to the air turbine 2B.

Reference numeral 3 denotes a rotary shaft that is rotatably supported by a static pressure air bearing 2C of the air motor 2. The tip of the rotary shaft 3 projects to the front side of the air motor 2 and the base end side thereof is an air turbine 2B of the air motor 2. Installed on. The rotary shaft 3 is rotationally driven at high speed by the air motor 2.

Reference numeral 4 is a bell-shaped rotary atomizing head provided at the tip of the rotary shaft 3, and the rotary atomizing head 4 is a cup-shaped outer peripheral surface 4A.
Is formed, and its inner peripheral surface serves as a paint smoothing surface 4B for smoothing paint discharged from a feed tube 5 described later. Further, the tip end side of the rotary atomizing head 4 is a paint discharge edge 4C for discharging the paint supplied from the paint smoothing surface 4B.

Reference numeral 5 denotes a feed tube which is provided so as to be inserted into the rotary shaft 3. The feed tube 5 supplies paint, thinner or the like to the rotary atomizing head 4, so that its tip portion projects from the rotary shaft 3. And extends into the rotary atomizing head 4. The feed tube 5 is connected to an external paint supply source (not shown) and supplies paint to the rotary atomizing head 4.

Reference numeral 6 is a shaping air ring screwed to the tip of the cover 1. The shaping air ring 6 is
The rotary atomizing head 4 is formed in a cylindrical shape using an insulating resin material.
It is located rearward of the paint discharge edge 4C and covers the outer peripheral surface 4A. Further, at the tip of the shaping air ring 6, a shaping air jet 7 (2
(Only one is shown) are arranged in an annular shape along the paint discharge edge 4C. The shaping air outlet 7 is an external shaping air source (not shown) via an air passage.
And ejects shaping air having a predetermined discharge pressure (air amount). As a result, the shaping air forms a spray pattern of the sprayed paint.

Reference numeral 8 denotes an electrode mounting member mounted on the rear end side of the cover 1. The electrode mounting member 8 has, for example, six support arms 8A extending radially around the rotary shaft 3 (air motor 2). However, the respective support arms 8A are spaced at substantially equal intervals in the circumferential direction.

Reference numeral 9 denotes an electrode rod attached to the support arm 8A of the electrode attaching member 8. The electrode rod 9 is located radially outside of the cover 1 and extends in the axial direction of the cover 1 and has a tip end thereof. , The external electrode 10 is attached. Further, the external electrode 10 extends axially from the tip of the electrode rod 9 toward the vicinity of the paint discharge edge 4C of the rotary atomizing head 4, and the tip thereof is located rearward of the paint discharge edge 4C. . The external electrode 10 is connected to an external high voltage generation source (not shown) and is applied with a high voltage of, for example, -60 to -120 kV.

The electrode mounting member 8 and the electrode rod 9 are made of an insulating resin material like the cover 1 and the like.

The rotary atomizing head type coating apparatus according to the prior art has the above-mentioned structure, and its operation will be described below.

First, each external electrode 1 is controlled by a high voltage source.
For example, a high voltage of −60 to −120 kV is applied to 0.
As a result, a negative ionization zone A is formed near the tip of the external electrode 15. Further, since the rotary atomizing head 4 and the object to be coated T are both connected to the ground, there is a space between the external electrode 10 and the rotary atomizing head 4 and between the external electrode 10 and the object to be coated T. An electrostatic field region is formed by the lines of electric force.

In this state, the rotary shaft 3 and the rotary atomizing head 4 are rotated at high speed by the air motor 2, and the paint supply source supplies the paint to the rotary atomizing head 4 through the feed tube 5. As a result, the paint supplied to the rotary atomizing head 4 flies out from the paint discharge edge 4C as atomized paint particles toward the outside in the radial direction.

At this time, since the rotary atomizing head 4 is rotating at a high speed, the paint particles discharged from the paint discharging edge 4C by the centrifugal force tend to be blown outward in the radial direction. However, by the shaping air ejected from the shaping air ejection port 7 of the shaping air ring 6, the paint particles are patterned so as to be squeezed forward.

As shown in FIG. 7, the sprayed paint particles are charged to a high voltage in the ionization zone A formed in front of the external electrode 10, and the charged paint particles are charged to the external electrode 10.
Flies along the electrostatic field formed between the object T to be coated and the object T to be grounded, and is applied to the surface of the object T to be coated.

On the other hand, some rotary atomizing head type coating devices are provided with one external electrode at the tip position projecting forward from the central portion of the rotary atomizing head. A rotary atomizing head type coating device is disclosed in, for example, Japanese Patent Laid-Open No. 6-5510.
It is known from the publication No. 6 and the like.

[0019]

By the way, in the above-mentioned rotary atomizing head type coating apparatus, the width dimension (the size of the cross section) of the spray pattern by the paint particles is the discharge amount of the paint, the viscosity of the paint, the rotary fog. It changes depending on the number of revolutions of the blush head 4, the ejection pressure of shaping air, the applied voltage of the external electrode 10, and the like.

On the other hand, as the position of the external electrode 10 is closer to the spray pattern, the coating particles are more easily charged, but at this time, the coating material tends to adhere to the external electrode 10 and easily become dirty. Therefore, the conventional rotary atomizing head type coating device is
The external electrode 10 is arranged on the outer peripheral side of the rotary atomizing head 4 according to the state in which the width dimension of the spray pattern is the widest. For this reason, only some of the paint particles sprayed toward the outer peripheral side can pass through the ionization zone A, and the paint particles passing through the axial center side of the rotary atomizing head 4 are in the ionization zone. It cannot pass Zone A. As a result, there is a problem in that the paint particles passing through the shaft center side of the rotary atomizing head 4 cannot be sufficiently charged, and the paint application efficiency decreases.

The external electrode 10 forms an electrostatic field with the object T to be coated. However, since the rotary atomizing head 4 is also connected to the ground similarly to the object to be coated T, an electrostatic field is formed between the external electrode 10 and the paint discharge edge 4C of the rotary atomizing head 4. At this time, since the external electrode 10 is arranged behind the paint discharge edge 4C of the rotary atomizing head 4, the external electrode 10 is larger than the distance dimension between the external electrode 10 and the rotary atomizing head 4.
The distance between the object T and the object to be coated T is overwhelmingly longer.

As a result, the electric field strength between the external electrode 10 and the object T to be coated becomes significantly lower than the electric field strength between the external electrode 10 and the rotary atomizing head 4, so that the charged paint particles There is also a problem that the force for conveying the coating material toward the article to be coated T is weakened, and the coating efficiency of the coating material is reduced.

Further, another conventional rotary atomizing head type coating apparatus according to Japanese Patent Laid-Open No. 6-55106 has only one external electrode projecting forward of the rotary atomizing head. Due to the narrow ionization sphere, the paint particles cannot be sufficiently charged to a high voltage, and there is a problem that the coating efficiency of the paint decreases.

Further, in the prior art, the function of shaping air is to accelerate the atomization of the paint particles, and the flight direction of the paint particles is directed toward the object to be coated T located in front of the rotary atomizing head 4. It has a function of controlling the spray pattern diameter. However, since these two functions are performed at high and low shaping air pressures (capacities), only one of the functions cannot be changed. For this reason, for example, when the shaping air pressure is increased to reduce the spray pattern diameter, the coating particles are accompanied by an unnecessarily small amount of particles, which accelerates the volatilization of volatile components in the coating particles, resulting in poor coating quality. There was a problem such as doing.

The present invention has been made in view of the above-mentioned problems of the prior art. The present invention can reliably charge the paint particles, and also conveys the charged paint particles to the object to be coated to enhance the coating efficiency. It is an object of the present invention to provide a rotary atomizing head type coating device that can be used.

[0026]

In order to solve the above-mentioned problems, a rotary atomizing head type coating apparatus according to the invention of claim 1 is provided with a rotary shaft rotated by a motor and provided at the tip of the rotary shaft. A rotary atomizing head that sprays the paint supplied from the discharge edge while rotating by the rotary shaft, and extends electrically in the rotary shaft in the axial direction, and is electrically insulated from the rotary atomizing head and the rotary shaft. The electrode rod provided in this state, and the tip of the electrode rod is divided into a plurality of branches toward the front of the rotary atomizing head, and the paint particles sprayed from the paint discharge edge of the rotary atomizing head are charged. Therefore, it is composed of a branch external electrode to which a high voltage is applied from the outside.

With this configuration, the paint particles discharged from the paint discharge edge of the rotary atomizing head are sprayed toward the object to be coated. At this time, in front of the rotary atomizing head, a branch external electrode is provided which is located at the tip of the electrode rod and is branched into a plurality of electrodes. An ionization zone can be formed across the side. As a result, the branch external electrode can charge the paint particles passing through a wide range from the shaft center side to the outer peripheral side to a high voltage.

The branched external electrode branched into a plurality of pieces is
Since the ionization zone is formed in a wide area in the circumferential direction in front of the rotary atomizing head, the paint particles discharged from the rotary atomizing head can be reliably charged to a high voltage by passing through the ionizing zone.

Further, since the branch external electrode is provided in front of the rotary atomizing head, the branch external electrode can be arranged between the rotary atomizing head and the object to be coated. Therefore, for example, the distance between the branch external electrode and the object to be coated can be made approximately the same as the distance between the branch external electrode and the rotary atomizing head, and thus the branch external electrode and the object to be coated can be compared to the conventional technique. It is possible to increase the strength of the electric field between and to strongly attract the charged paint particles toward the object to be coated, and to improve the coating efficiency of the paint.

According to the second aspect of the present invention, the branched external electrodes are provided so as to be inclined with respect to the axial center so that the respective tip ends face the outer peripheral side.

With this configuration, since the tip end side of the branch external electrode is inclined with respect to the axis center so as to face the outer peripheral side, the axis of the rotary atomizing head is extended along the extension line of the branch external electrode. An ionization zone can be formed from the center toward the outer peripheral side, and any paint particles passing through the shaft center side and the outer peripheral side can be charged to a high voltage.

According to the invention of claim 3, a shaping air ring is provided on the outer peripheral side of the rotary atomizing head, and the shaping air ring ejects shaping air for forming a spray pattern of the sprayed paint. An outlet is provided, and a pushing air ejection port for ejecting pushing air for pushing the sprayed paint toward the shaft center is provided on the outer peripheral side of the shaping air ejection port.

With this configuration, when the discharge pressure of the shaping air is high, the paint particles become smaller and the width dimension of the spray pattern also becomes smaller. on the other hand,
When the discharge pressure of the shaping air is low, the paint particles become large and the width dimension of the spray pattern also becomes large. Therefore, when the discharge pressure of the shaping air is low, the spray pattern may spread and the paint particles may fall out of the ionization zone.

On the other hand, since the pushing air ejection port is provided on the outer peripheral side of the shaping air ejection port, by ejecting the pushing air from the pushing air ejection port, the paint particles spreading toward the outer peripheral side are directed toward the shaft center. Can be pushed in. Therefore, regardless of the size of the paint particles, the paint particles can be sprayed so as to pass through the ionization zone formed in front of the rotary atomizing head by the branch external electrode, and the paint particles are charged to a high voltage. be able to.

According to the fourth aspect of the present invention, in the branch external electrode, the distance dimension between the tip of the branch external electrode and the paint discharge edge of the rotary atomizing head is the tip of the branch external electrode and the object to be coated. It is located at a position almost equal to the distance dimension between.

As a result, the electric field strength between the branched external electrode and the object to be coated can be made approximately the same as the electric field strength between the external electrode and the rotary atomizing head, and as in the prior art, the external electrode and The electric field strength is not biased between the rotary atomizing head and the electric field strength between the branched external electrode and the object to be coated. Therefore, the charged paint particles can be strongly attracted toward the object to be coated, and the coating efficiency of the paint can be improved.

[0037]

DETAILED DESCRIPTION OF THE INVENTION A rotary atomizing head type coating apparatus according to an embodiment of the present invention will be described below with reference to FIGS. In this embodiment, the same components as those of the conventional technique are designated by the same reference numerals, and the description thereof will be omitted.

Reference numeral 11 denotes a cover forming the outer shape of the rotary atomizing head type coating apparatus. The cover 11 is formed in a cylindrical shape using, for example, an insulating resin material, and an air motor 12 described later is housed therein. .

Reference numeral 12 is an air motor housed in the cover 11. The air motor 12 includes a motor body 12A, an air turbine, and a static pressure air bearing (all not shown) as in the air motor 2 described in the prior art. It is configured. Then, the air motor 12 rotationally drives a rotary shaft 13 described later by supplying high-pressure air to the air turbine.

Reference numeral 13 is a hollow rotary shaft rotatably supported by a static pressure air bearing of the air motor 12, and the rotary shaft 13 is
The tip end thereof protrudes to the front side of the air motor 12, and the base end side thereof is attached to the air turbine of the air motor 12. The rotary shaft 13 is rotationally driven at high speed by the air motor 12.

Reference numeral 14 denotes a bell-shaped rotary atomizing head provided at the tip of the rotary shaft 13, and the rotary atomizing head 14 applies the paint supplied from a feed tube 15 described later while rotating by the rotary shaft 13. It is atomized. The rear side of the rotary atomizing head 14 is a stepped cylindrical mounting portion 14A that is screwed to the tip of the rotating shaft 13, and the front side is a cup-shaped paint spraying portion 14B that spreads forward. ing. Further, the front surface side of the paint spraying section 14B becomes a paint smoothing surface 14C for smoothing the paint, and the tip side of the paint spraying section 14B is
It is a paint discharge edge 14D for discharging the paint supplied from the paint smoothing surface 14C. On the other hand, a paint receiving portion 14F is formed by the stepped cylindrical portion 14E on the rear surface side of the paint spraying portion 14B. Furthermore, the paint sprayer 14B
From the depth of the paint receiving portion 14F to the paint smoothing surface 14
A large number of paint outflow holes 14G reaching C are arrayed in an annular shape.

Reference numeral 15 is a feed tube provided on the outer peripheral side of the rotary shaft 13. The feed tube 15 supplies paint and thinner to the rotary atomizing head 14, and the base end side is attached to the cover 11 and the tip end. The side is open to the paint receiving portion 14F of the rotary atomizing head 14. The feed tube 15 is connected to an external paint supply source (not shown).

Reference numeral 16 denotes a shaping air ring screwed to the tip of the cover 11, and the shaping air ring 1
Reference numeral 6 is formed in a cylindrical shape using an insulating resin material, and is located rearward of the paint discharge edge 14D of the rotary atomizing head 14 and covers the paint spraying portion 14B. Further, at the tip of the shaping air ring 16, shaping air jets 17 composed of a large number of small holes are arranged in a ring shape along the paint discharge edge 14D. And shaping air jet 1
7 is connected to an external shaping air source (not shown) via an air passage and ejects shaping air having a predetermined discharge pressure (air amount). As a result, the shaping air forms a spray pattern of the paint sprayed from the rotary atomizing head 14.

Reference numeral 18 denotes an auxiliary cover which is provided so as to cover the outer peripheral side of the shaping air ring 16 and is formed of an insulating resin material. The auxiliary cover 18 is located at the tip of the auxiliary cover 18 between the outer peripheral surface of the shaping air ring 16. In addition, the pushing air ejection ports 19 composed of a large number of small holes are arranged in a ring shape. The pushing air ejection port 19 is located on the outer peripheral side of the shaping air ejection port 17, and the rotary atomizing head 1 is provided.
Inject air from the outer peripheral side of 4 toward the center of the shaft.
As a result, the paint particles sprayed from the rotary atomizing head 14 are squeezed forward without being excessively spread to form a spray pattern having a predetermined width.

Reference numeral 20 is an electrode rod fixedly provided so as to extend in the rotating shaft 13 in the axial direction. The electrode rod 20 is formed of an insulating resin material or an insulating ceramic material into a columnar shape. By rotating shaft 13 and rotating atomizing head 1
4 and 4 are electrically insulated. Also, the electrode rod 2
In the case of 0, the tip end side is a protrusion 20A that protrudes forward of the rotary atomizing head 14, and a branch external electrode 22 described later is provided at the tip end of the protrusion 20A. Furthermore, the electrode rod 2
In No. 0, a disc-shaped shield plate 20B, which is located on the rear side of the protrusion 20A and prevents the paint particles from entering the gap between the electrode rod 20 and the rotary shaft 13, is provided. .

Reference numeral 21 denotes a high resistance provided in the electrode rod 20 so as to extend in the axial direction. The high resistance 21 is provided between a high voltage generator (not shown) and a branch external electrode 22 described later. ing. The high resistance 21 prevents spark discharge when the branch external electrode 22 abnormally approaches the object T to be coated. The high resistance 21 is, for example, 100 MΩ or more.
It is set to a value of 1000 MΩ.

Reference numeral 22 denotes a branching external electrode provided so as to project forward from the tip of the projecting portion 20A of the electrode rod 20, and the branching external electrode 22 is divided into a plurality of branches toward the front of the rotary atomizing head 14. A plurality of, for example, four needle electrodes 22A, 22A, ... Are provided. here,
Each needle-shaped electrode 22A that constitutes the branched external electrode 22 is connected to the tip of the high resistance 21. As a result, the branch external electrode 22 is, for example, -60 to -120 from the high voltage generator.
When a high voltage of kV is applied, an ionization zone B for charging the paint particles sprayed from the paint discharge edge 14D of the rotary atomizing head 14 is formed.

Then, each needle-shaped electrode 2 of the branch external electrode 22
As shown in FIGS. 1 and 2, 2A is, for example, 20 ° to 70 with respect to the axial center of the rotary shaft 13 so that the tip end side faces the outer peripheral side.
Inclined at an angle θ of °, preferably 45 °.

Here, the needle-shaped electrode 22 of the branch external electrode 22
When the distance between the tip of A and the paint discharge edge 14D of the rotary atomizing head 14 is L1 and the distance between the tip of the needle-shaped electrode 22A and the object T is L2, the distance is L1 is less than 0.75 times the distance L2 (L1 ≤ 0.75 x L
2) or 1.5 times or more (L1 ≧ 1.5 × L2), it has been experimentally confirmed that the coating efficiency of the paint is lowered to, for example, about 87%.

Therefore, as shown in FIG. 3, the needle-shaped electrode 22A has its tip and the paint discharge edge 14 of the rotary atomizing head 14.
The distance dimension L1 with D is almost equal to the distance dimension L2 between the tip and the object T (0.75 × L2 <L1 <
1.5 × L2, preferably L1≈L2).

The rotary atomizing head type coating apparatus according to the present embodiment has the above-mentioned structure, and its operation will be described below.

First, a high voltage of, for example, -60 to -120 kV is applied to the branch external electrode 22 by the high voltage generator. Thereby, each needle-shaped electrode 22A of the branch external electrode 22
An electrostatic field region due to the lines of electric force is formed between each of the needle-shaped electrodes 22A and the rotary atomizing head 14 and between each of the needle-shaped electrodes 22A and the object to be coated T, and a minus electric field is formed near each tip of the needle-shaped electrodes 22A. The ionization zone B of is formed.

In this state, the rotary shaft 13 and the rotary atomizing head 14 are rotated at high speed by the air motor 12, and
The paint supply source supplies paint to the rotary atomizing head 14 through a feed tube 15. As a result, the coating material supplied to the rotary atomizing head 14 is applied to the paint discharge edge 14 of the rotary atomizing head 14.
It flies from D toward the radially outer side as atomized paint particles.

On the other hand, shaping air is blown around the paint discharge edge 14D from the shaping air jet port 17 located behind the edge 14D. This promotes atomization (atomization) of the paint, so that the paint particles become small when the shaping air discharge pressure is high, and become large when the shaping air discharge pressure is low.

Further, when the discharge pressure of shaping air is high, the width of the spray pattern is narrow, whereas when the discharge pressure of shaping air is low, the width of the spray pattern is wide. Therefore, the pushing air ejection port 19 provided on the outer peripheral side of the shaping air ejection port 17 ejects the pushing air according to the discharge pressure of the shaping air to keep the width of the spray pattern constant.

Then, the paint particles narrowed down to the axial center side of the rotary atomizing head 14 pass through the area around the branch external electrode 22 which is branched into four toward the front of the rotary atomizing head 14.
At this time, since the ionization zone B is formed toward the outer peripheral side at the tip side of the four needle-shaped electrodes 22A constituting the branch external electrode 22, the area in front of the rotary atomizing head 14 is radially formed. It can be covered by a plurality of ionization zones B arranged in line. Therefore, the paint particles are in the ionization region B
Since it will pass through, it is surely charged to a high voltage.

On the other hand, the distance dimension L1 between the tip of the branch external electrode 22 and the paint discharge edge 14D of the rotary atomizing head 14 is the distance dimension L2 between the tip of the branch external electrode 22 and the object T to be coated.
Since the branch external electrode 22 is disposed so as to have a distance substantially equal to that of the branch external electrode 22, the electric field strength is not biased between the branch external electrode 22 and the rotary atomizing head 14 as in the prior art, and the branch external electrode 22 and The electric field strength between the coating material T and the branch external electrode 22 and the rotary atomizing head 14 can be made substantially the same. Therefore, the electric field strength between the branch external electrode 22 and the article to be coated T can be increased as compared with the conventional technique.

As a result, the charged paint particles charged by the ionization zone B fly toward the object T to be coated along the electrostatic field between the branch external electrode 22 and the object T to be coated, and at the same time, the charged paint particles. Can be strongly attracted toward the article to be coated T, and the coating efficiency of the paint can be improved.

Thus, according to the present embodiment, the electrode rod 20 which extends in the axial direction in the rotary shaft 13 and whose tip projects in front of the rotary atomizing head 14 is provided, and the projecting portion 20A of the electrode rod 20 is provided.
Since the branch external electrode 22 that is branched into four is provided at the tip toward the front of the rotary atomizing head 14, the branch external electrode 22 extends in front of the rotary atomizing head 14 from the axial center side to the outer peripheral side. The ionization zone B can be formed, and the paint particles passing through a wide range from the axial center side of the rotary atomizing head 14 to the outer peripheral side can be charged to a high voltage.

The branch external electrode 22 is composed of four needle-shaped electrodes 22A, so that the rotary atomizing head 14 is
Since the ionization sphere B can be formed in a wide area in the circumferential direction in front of, the paint particles released from the rotary atomizing head 14 can be passed through the ionization sphere B, and the paint particles are surely discharged. It can be charged to a high voltage.

Further, the branch external electrode 22 is attached to the rotary atomizing head 14
The branch external electrode 22 can be disposed between the rotary atomizing head 14 and the object T to be coated by providing the branch external electrode 22 in front of.
Therefore, the electric field strength between the branched external electrode 22 and the article to be coated T can be increased as compared with the conventional technique, and thus the charged paint particles can be strongly attracted toward the article to be coated T,
The coating efficiency of the paint can be improved.

Moreover, since the tip end side of each needle-shaped electrode 22A constituting the branch external electrode 22 is inclined at an angle θ with respect to the axis center so as to face the outer peripheral side, the needle-shaped electrode 22
An ionization zone B can be formed from the axial center of the rotary atomizing head 14 toward the outer circumferential side along the extension line of A, and any paint particles passing through the axial central side and the outer circumferential side are charged to a high voltage. Can be made.

Further, since the shaping air ring 16 having the shaping air jet 17 is provided on the outer peripheral side of the rotary atomizing head 14 and the pushing air jet 19 is provided on the outer circumferential side of the shaping air jet 17, pushing By ejecting pushing air from the air ejection port 19,
The paint particles that spread toward the outer peripheral side can be pushed toward the center of the shaft. Therefore, regardless of the size of the paint particles, the paint particles can be sprayed through the axial center side where the ionization zone B is formed, and the paint particles can be efficiently charged.

Further, the distance dimension L1 between the tip of the branch external electrode 22 and the paint discharge edge 14D of the rotary atomizing head 14 is the distance dimension L between the tip of the branch external electrode 22 and the object T to be coated.
Since the branch external electrode 22 is arranged at a position substantially equal to 2, the electric field strength between the branch external electrode 22 and the object to be coated T is made approximately equal to the electric field strength between the external electrode 22 and the rotary atomizing head 14. can do. Therefore, unlike the prior art, the electrostatic field is not biased between the branch external electrode 22 and the rotary atomizing head 14, and the electric field strength between the branch external electrode 22 and the object to be coated T can be increased. . As a result, the charged paint particles can be strongly attracted toward the object to be coated, and the coating efficiency of the paint can be increased.

In the embodiment, the branch external electrode 22 is used.
Is the four needle-shaped electrodes 22 connected to the tip of the high resistance 21.
Although the case of being configured by A has been described as an example, the present invention is not limited to this and, for example, as in a modification shown in FIG.
The branched external electrode 31 may be configured by one trunk portion 31A connected to the high resistance 21 and a plurality of needle-shaped electrode portions 31B, 31B, ... That are radially branched from the tip of the trunk portion 31A.

Further, in the embodiment, the branch external electrode 22 is used.
Has been described by taking as an example the case of being constituted by four needle-shaped electrodes 22A, but the present invention is not limited to this.
The branched external electrode may be composed of 2, 3 or 5 or more needle electrodes. This structure can be similarly applied to the above-described modified example.

Further, in the embodiment, the air motor 12
However, the present invention is not limited to this, and the rotation shaft may be rotated by using, for example, an electric motor.

[0068]

As described above in detail, according to the invention of claim 1, the tip of the electrode rod extending axially in the rotary shaft is branched into a plurality of branches toward the front of the rotary atomizing head. Since the external electrode is provided, an ionization zone can be formed in front of the rotary atomizing head from the axial center side to the outer peripheral side, and a wide range from the axial center side to the outer peripheral side can be formed. The paint particles passing through can be charged to a high voltage.

The branched external electrode branched into a plurality of pieces is
An ionization zone can be formed in a wide area in front of the rotary atomizing head, and the paint particles discharged from the rotary atomizing head can be reliably charged to a high voltage. Further, since the branched external electrode is provided in front of the rotary atomizing head, the external electrode can be arranged between the rotary atomizing head and the object to be coated. Therefore, the electric field strength between the branched external electrode and the object to be coated can be increased as compared with the conventional technique, so that the charged paint particles can be strongly attracted toward the object to be coated and the coating efficiency can be improved. Can be increased.

According to the invention of claim 2, since the branch external electrodes are provided so as to be inclined with respect to the axial center so that the respective tip ends face the outer peripheral side, the branch external electrodes are provided on the respective extension lines of the branch external electrodes. Along with this, an ionization zone can be formed from the axial center of the rotary atomizing head toward the outer peripheral side, and any paint particles passing through the axial center side and the outer peripheral side can be charged to a high voltage.

According to the invention of claim 3, a shaping air ring is provided on the outer peripheral side of the rotary atomizing head, a shaping air jet is provided on the shaping air ring, and an outer peripheral side of the shaping air jet is provided. Since the pushing air ejection port is provided, the paint particles spreading toward the outer peripheral side can be pushed toward the axial center by ejecting the pushing air from the pushing air ejection port. Therefore, regardless of the size of the paint particles, the paint particles can be sprayed through the axial center side where the ionization zone is formed, so that the paint particles can be efficiently charged to a high voltage.

According to the invention of claim 4, in the branch external electrode, the distance dimension between the tip of the branch external electrode and the paint discharge edge of the rotary atomizing head is the tip of the branch external electrode and the object to be coated. Since it is arranged at a position almost equal to the distance dimension between the branch external electrode and the object to be coated, the electric field strength between the branch external electrode and the rotary atomizing head can be made approximately the same. Therefore, the electric field strength between the branched external electrode and the object to be coated can be increased. Therefore, the charged paint particles can be strongly attracted toward the object to be coated, and the coating efficiency of the paint can be improved.

[Brief description of drawings]

FIG. 1 is a partially cutaway front view showing a rotary atomizing head type coating apparatus according to the present embodiment.

FIG. 2 is a left side view of the rotary atomizing head type coating device as viewed in the direction of arrows II-II in FIG.

FIG. 3 is a partially cutaway front view showing a state in which an object to be coated is coated using the rotary atomizing head type coating apparatus according to the present embodiment.

FIG. 4 is an explanatory diagram showing a relationship between a branched external electrode, an ionization zone, and a spray pattern of a paint, as viewed in the direction of arrows IV-IV in FIG.

FIG. 5 is a partially cutaway front view showing a rotary atomizing head type coating apparatus including a branched external electrode according to a modification.

FIG. 6 is a partially cutaway front view showing a rotary atomizing head type coating apparatus according to the prior art.

FIG. 7 is a front view showing a state in which an object to be coated is being coated using a rotary atomizing head type coating device according to the prior art.

[Explanation of symbols]

12 air motor (motor) 13 rotary shaft 14 rotary atomizing head 14D paint discharge edge 16 shaping air ring 17 shaping air jet 19 push air jet 20 electrode rod 20A protrusions 22, 31 branch external electrode 22A needle electrode 31A stem 31B Needle-shaped electrode portion θ Angle of external electrode L1 Distance dimension between tip of branching external electrode and paint discharge edge of rotary atomizing head L2 Distance dimension between tip of branching external electrode and object to be coated

Claims (4)

[Claims] 1. A rotary shaft which is rotated by a motor, a rotary atomizing head which is provided at a tip of the rotary shaft and sprays paint supplied from a discharge edge while being rotated by the rotary shaft, and the rotary shaft. An electrode rod extending in the axial direction and electrically insulated from the rotary atomizing head and the rotary shaft, and a plurality of electrodes are branched at the tip of the electrode rod toward the front of the rotary atomizing head. A rotary atomizing head type coating device provided with a branch external electrode to which a high voltage is applied from outside in order to charge paint particles sprayed from the paint discharge edge of the rotary atomizing head. 2. The rotary atomizing head type coating device according to claim 1, wherein each of the branch external electrodes is provided so as to be inclined with respect to an axial center so that each tip side faces the outer peripheral side. 3. A shaping air ring is provided on the outer peripheral side of the rotary atomizing head, and the shaping air ring is provided with a shaping air ejection port for ejecting shaping air for forming a spray pattern of sprayed paint. The rotary atomizing head type coating device according to claim 1 or 2, wherein a pushing air jet port for jetting pushing air for pushing the sprayed paint toward the shaft center is provided on the outer peripheral side of the shaping air jet port. 4. In the branch external electrode, the distance between the tip of the branch external electrode and the paint discharge edge of the rotary atomizing head is the distance between the tip of the branch external electrode and the object to be coated. 4. The structure is arranged at a position substantially equal to the size.
The rotary atomizing head type coating device described in.