JP2001113207A - Electrostatic coating device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electrostatic coating device, in which coating particles are difficult to be stuck without relation to the material of resin material used for a cover member. SOLUTION: An air motor 2 is fitted on the inner peripheral side of a housing 1 and a rotary atomization head 3 is fitted to the tip of the air motor 2. Further, a cover 8 is fitted on the outer peripheral side of the housing 1 through a retainer ring 9. The air motor 2 is housed in the inside of the cover 8 and also a shaping air ring 10 covering the outer peripheral side of the rotary atomization head 3 is fitted to the front end of the cover 8. Further, a supporting arm 13 extended toward the rotary atomization head 3 is provided in the outside in the direction of the diameter of the housing 1, and also an external electrode 14 connected to a high voltage generator 15 is fitted to the tip of the supporting arm 13. The housing 1, the cover 8, the retainer ring 9, the shaping air ring 10 and the supporting arm 13 are formed of an insulating resin material and also a water repellent film 16 is provided on the surfaces thereof to prevent coating particles from adhering.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrostatic coating apparatus for spraying charged atomized paint particles toward an object to be coated along lines of electric force.

[0002]

2. Description of the Related Art In general, an electrostatic coating apparatus having a high coating efficiency is used for coating an object to be coated such as a vehicle body. Such an electrostatic coating apparatus sprays a supplied paint on the object to be coated. A paint spraying means, a cover member formed of an insulating material and accommodating the paint spraying means, and a high voltage for charging the paint particles sprayed from the paint spraying means to a high voltage and applying the charged paint particles to an object to be coated. And an application unit. Also,
Such electrostatic coating apparatuses include a direct charging type and an indirect charging type.

[0003] Here, a direct charging type electrostatic coating apparatus is
The charged paint particles are sprayed by directly applying a high voltage to the paint before atomization, and the charged paint particles are caused to fly along the lines of electric force formed between the coating device and the object to be coated. It is to be applied to objects. On the other hand, with an indirect charging type electrostatic coating device, a high voltage is applied to an external electrode, and paint particles sprayed from the coating device are charged while passing through a corona discharge region formed in front of the external electrode, The charged paint particles are caused to fly along the lines of electric force formed between the external electrode and the object to be coated, and are applied to the object to be coated.

[0004] The electrostatic coating apparatus according to the prior art is
Regardless of the direct charging type or the indirect charging type, the outer surface of the cover member is charged with a charge having substantially the same potential at the same polarity as the discharged high voltage, and the charged paint particles The cover member repels to prevent paint particles from adhering to the outer surface of the cover member.

[0005] In another conventional electrostatic coating apparatus, there is known an electrostatic coating apparatus in which a water-repellent insulating resin material such as PTFE (polytetrafluoroethylene) is used for a cover member (for example, Japanese Patent Publication No. Hei 6 (1994)). -61491).

[0006]

In the electrostatic coating apparatus according to the prior art, an insulating resin material is used for the cover member, but the electric repulsion does not function effectively. For this reason, there is a problem that the sprayed paint particles easily adhere to the cover member.

That is, when the spray pattern of the paint is shaped using the shaping air, a so-called air pumping phenomenon occurs in which the air around the cover member is entrained by the shaping air. For this reason, the paint particles may be sprayed toward the cover member due to the air pumping phenomenon, and may adhere to the cover member as dirt.

When it is not possible to sufficiently charge the paint particles with a high voltage, floating particles having a small charge amount may drift around the cover member. At this time, since the cover member made of an insulating material is charged to substantially the same potential as the charged paint particles, the floating particles may be attracted to and adhere to the cover member charged to a high voltage.

Further, when the cover member made of a resin material absorbs the moisture in the air around the coating device, the degree of insulation of the cover member decreases and the cover member approaches the ground potential. May be attracted.

As described above, the paint particles adhering to the cover member accumulate as dirt (continuous film) having a low electric resistance, and the dirt is transmitted along the outer surface of the cover member to cause static electricity to leak, and the paint particles adhere. In addition to the above, there is a problem that the coating efficiency of the coating material is remarkably reduced, and the paint adhered to the cover member lowers the degree of insulation of the outer surface of the coating device, making it impossible to continue the coating.

Further, when paint particles adhere to and accumulate on the surface of the cover member, the deposited paint peels off from the cover member and becomes peeled pieces. For this reason, there is a problem that if the peeled piece falls onto the object to be coated, the coating quality of the object to be coated is reduced.

On the other hand, in another conventional electrostatic coating apparatus described in Japanese Patent Publication No. 6-61491, a cover member is formed of a water-repellent resin material such as PTFE (polytetrafluoroethylene). I have. For this reason, even when paint particles fly to the cover member,
Due to the water repellency of the PTFE, the paint particles are repelled and raised substantially hemispherically on the surface of the cover member. For this reason, in the other conventional electrostatic coating apparatus, the coating particles can be continued without the coating particles being deposited on the surface of the cover member.

However, PTFE used for a cover member of an electrostatic coating apparatus is, for example, POM (polyoxymethylene), PET (polyethylene terephthalate), PP
(Polypropylene)
It has low mechanical strength, such as easy damage, and poor machinability. For this reason, in a coating apparatus using PTFE as a cover member as in other related arts, it is necessary to design the cover member to be thick in order to increase the mechanical strength of the cover member, which increases the weight of the coating apparatus. However, the size of the coating apparatus tends to increase. As a result, when the coating device is mounted on a movable arm such as a robot or a reciprocator, and the coating is performed while moving at a high speed, an excessive load is applied to the movable arm with an increase in the weight of the coating device.
There is a problem that functions of a reciprocator and the like are reduced.

Further, since PTFE is poor in mechanical workability, there is a problem that the number of processing steps in the manufacturing process of the cover member increases, the product yield is low, and the manufacturing cost is high.

The present invention has been made in view of the above-mentioned problems of the prior art, and the present invention provides an electrostatic coating apparatus in which paint particles hardly adhere to the outer surface of the cover member regardless of the material of the resin material used for the cover member. It is intended to provide.

[0016]

According to a first aspect of the present invention, there is provided a paint spraying means for spraying a supplied paint onto an object to be coated, and a paint spraying means formed of an insulating material. A cover member for accommodating a spraying means, and a high voltage applying means for charging the paint particles sprayed from the paint spraying means to a high voltage and applying the charged paint particles to an object to be coated; On the surface of the cover member, a water-repellent film having an electrical insulating property for preventing the charged paint particles from adhering is provided.

With this configuration, even when the charged paint particles sprayed from the paint spraying means fly to the surface of the cover member, the paint particles can be repelled by the water-repellent film, and the adhesion of the paint particles can be reduced. Can be prevented.

The invention according to claim 2 is that the cover member is formed of an insulating resin material having a contact angle with water of 60 ° or less.

In this case, the contact angle between the cover member and water is 6
Since the angle is 0 ° or less, paint particles easily adhere to the cover member. However, since a water-repellent film is provided on the surface of the cover member, the paint particles can be repelled by the water-repellent film even in a cover member to which the paint particles are easily attached, so that the paint particles are prevented from being attached. Can be.

Further, the invention of claim 3 is that the water-repellent film has a contact angle with water of 80 ° or more.

Thus, even when the charged paint particles fly to the surface of the cover member, the paint particles are raised almost in a semispherical shape on the water-repellent film and are repelled. Therefore, the adhesion of the paint particles is prevented by the water-repellent film. And at the same time, the attached paint particles can be easily removed.

Further, the invention of claim 4 is that silica powder or glass powder is added to the water-repellent film.

Thus, the contact angle between the water-repellent film and the water can be increased, so that the paint particles are repelled by the water-repellent film and the paint particles are reliably prevented from adhering to the water-repellent film. it can.

Further, the invention of claim 5 is that the water-repellent film is made of a polymethylsiloxane resin paint.

Thus, the contact angle between the water-repellent film and water is set to 8
Since it can be 0 ° or more, even when the charged paint particles fly on the surface of the cover member, the charged paint particles can be flipped on the water-repellent film, and the paint particles adhere to the surface of the cover member. Can be prevented.

According to a sixth aspect of the present invention, the paint spraying means is provided with an air motor and a rotary atomizer located at the front end side of the air motor and rotatably provided by the air motor, and having a tip as a paint discharge edge. It consists of a head and a cover member,
A cover for accommodating the air motor, and a shaping air ring provided on the tip side of the cover so as to cover an outer peripheral side of the rotary atomizing head, and configured to eject shaping air from an air ejection port. Is provided with a water-repellent film on the surface of the cover and the shaping air ring.

Thus, even when the charged paint particles sprayed from the rotary atomizing head fly to the surface of the cover or shaping air ring, the charged paint particles can be repelled by the water-repellent film, and the paint particles can be applied to the cover or the like. Can be prevented from adhering.

According to a seventh aspect of the present invention, the high voltage applying means includes a support arm located outside the cover and extending toward the vicinity of the rotary atomizing head, and a rotary atomizer provided at a tip of the support arm. An external electrode to which a high voltage is applied from the outside to charge the paint particles sprayed from the head is provided, and a water-repellent film is provided on the surface of the support arm.

Thus, even when the charged paint particles from the rotary atomizing head come to the support arm supporting the external electrode, the paint particles can be repelled by the water-repellent film provided on the support arm. It is possible to prevent paint particles from adhering to the support arm.

Further, according to the invention of claim 8, the high voltage applying means applies a high voltage from the outside to the air motor and directly applies the high voltage to the paint before atomization supplied to the rotary atomizing head. It is in the configuration.

As a result, the paint before atomization supplied to the rotary atomizing head is charged to a high voltage via the air motor and the rotary atomizing head, so that the paint is applied to the object as charged paint particles. I do. Even when the charged paint particles sprayed from the rotary atomizing head fly over the surface of the cover and the shaping air ring, the charged paint particles can be repelled by the water-repellent film.

[0032]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an electrostatic coating apparatus according to an embodiment of the present invention will be described in detail with reference to FIGS.

First, FIGS. 1 to 3 show a rotary atomizing type coating machine as an electrostatic coating apparatus according to a first embodiment of the present invention.

In the drawing, reference numeral 1 denotes a substantially cylindrical housing constituting the main body of the coating machine, and a cylindrical portion 1A protruding in a substantially cylindrical shape is provided on the front side of the housing 1, and the cylindrical portion 1A is provided.
Inside, an air motor 2 described later is mounted.
A screw portion 1B is provided on the outer peripheral side of the housing 1, and a retainer ring 9 described later is screwed to the screw portion 1B. The housing 1 is, for example, POM
(Polyoxymethylene), PET (polyethylene terephthalate), PP (polypropylene), HP-PE (high-pressure polyethylene), HP-PVC (high-pressure vinyl chloride),
It is formed of an insulating resin material such as PEI (polyetherimide), PES (polyethersulfone), and polymethylpentene.

Reference numeral 2 denotes an air motor mounted in the cylindrical portion 1A of the housing 1. The air motor 2 includes a cylindrical motor body 2A, an air turbine 2B housed in the motor body 2A, and a base. It comprises a rotating shaft 2C having an end attached to the air turbine 2B and a leading end projecting toward the front of the air motor 2, and a hydrostatic air bearing 2D rotatably supporting the rotating shaft 2C. The air motor 2 is driven to rotate by supplying pressurized air to the air turbine 2B.

Reference numeral 3 denotes a bell-shaped rotary atomizing head provided at the tip of the rotary shaft 2C. The rotary atomizing head 3 has a cup-shaped outer peripheral surface 3A, and the inner peripheral surface of the rotary atomizing head 3. Are paint smoothing surfaces 3B for smoothing paint discharged from a feed tube 4 described later. The tip side of the rotary atomizing head 3 is a paint discharge edge 3C for discharging paint supplied from the paint smoothing surface 3B.

Reference numeral 4 denotes a feed tube which is inserted through the rotary shaft 2C. The feed tube 4 supplies paint, thinner, and the like to the rotary atomizing head 3 so that its tip side projects from the rotary shaft 2C. It extends into the rotary atomizing head 3.
The feed tube 4 has a proximal end extending into the housing 1 and is connected to a paint valve 5 including an air cylinder provided in the housing 1.

Further, the feed tube 4 is connected to the housing 1.
Through a drain valve (not shown), and is connected to a drain tank 7 that collects a drain during color change via a drain valve (not shown). The feed tube 4 discharges the paint supplied from the color changing valve device 6 toward the rotary atomizing head 3 in accordance with opening and closing of the paint valve 5.

8 is a shaping air ring 10 to be described later.
The cover 8 is a cover forming a cover member of the rotary atomizing type coating machine. The cover 8 is formed in a thin cylindrical shape, and is formed on the housing 1 by an annular retainer ring 9 screwed to the screw portion 1B of the housing 1. The air motor 2 is mounted so as to protrude forward, and houses the air motor 2 therein. The cover 8 and the retainer ring 9 are made of the same resin material as the housing 1 such as POM (polyoxymethylene), PET (polyethylene terephthalate), PP
(Polypropylene), HP-PE (high-pressure polyethylene), HP-PVC (high-pressure vinyl chloride), PEI (polyetherimide), PES (polyethersulfone),
It is formed of an insulating resin material such as polymethylpentene, and these insulating resin materials are set to have a contact angle with water of 60 ° or less as shown in Table 1 described later.

Reference numeral 10 denotes a shaping air ring screwed to the tip of the cover 8.
Is formed in a cylindrical shape as shown in FIG. 2, and is located behind the paint discharge edge 3C of the rotary atomizing head 3 and covers the outer peripheral surface 3A. Further, the shaping air ring 10 is formed of the same insulating resin material as the cover 8, and has a large number of air ejection ports 11 (only two are shown) arranged in an annular shape at the tip. The air outlet 11 is connected to a shaping air source (not shown) provided outside the cover 8, and discharges shaping air supplied from the shaping air source.

Reference numeral 12 denotes an annular electrode mounting ring disposed on the rear end side of the housing 1 so as to surround the housing 1. The electrode mounting ring 12 has, for example, six (two) (Only shown). Each support arm 13 is made of the same insulating resin material as the cover 8 and the like, and is located radially outside the housing 1 and extends in the axial direction of the cover 8. An external electrode 14 is attached to the tip of each support arm 13, and the external electrode 14 extends in the axial direction from the tip of the support arm 13 toward the vicinity of the paint discharge edge 3 </ b> C of the rotary atomizing head 3. ing. The external electrode 14 is connected to a high-voltage generator 15 provided outside the housing 1, for example, from −60 to −12.
A high voltage of about 0 kV is applied. Thus, the external electrode 14 charges the paint particles sprayed from the paint discharge edge 3C of the rotary atomizing head 3.

In the rotary atomizing type coating machine described above,
The housing 1, the cover 8, the retainer ring 9, the shaping air ring 10, and the outer surface of the support arm 13, which are located around the rotary atomizing head 3 for spraying paint, have a water-repellent film 1 to be described later.
The provision of the coating 6 prevents the adhesion of paint particles.

Here, the water-repellent film 16 includes a film portion 16A provided on the surface of the housing 1, a film portion 16B provided on the surface of the cover 8, a film portion 16C provided on the surface of the retainer ring 9,
The film part 16 provided on the surface of the shaping air ring 10
D, and a film portion 16E provided on the surface of the support arm 13. The film portions 16A to 16E are provided with substantially the same water-repellent film 16. For this reason, the water repellent film 16 composed of the film portion 16D provided on the outer surface of the shaping air ring 10 will be described below with reference to FIG.

In FIG. 3, reference numeral 16 denotes a water-repellent film provided on the outer surface of the shaping air ring 10. The water-repellent film 16 has, for example, a polymethylsiloxane-based resin paint 17 which is a kind of silicone resin paint. Is used.
The water-repellent film 16 is formed by applying the polymethylsiloxane-based resin paint 17 to the outer surface of the shaping air ring 10. The water-repellent film 16 has a volume specific resistance of, for example, about 10 ¹⁷ Ω / cm, and has electrical insulation.

The thickness of the water repellent film 16 is set to at least 1 μm in order to obtain stable water repellency. On the other hand, if the thickness of the water-repellent film 16 is too large, the cohesive force of the coating film decreases, and the adhesion cannot be maintained. For this reason, the thickness of the water-repellent film 16 is set to a value that provides appropriate water-repellency and adhesion within a range of, for example, about 1 to 9 μm according to the type of the polymethylsiloxane-based resin paint 17.

Assuming that the contact angle of the water-repellent film 16 with the paint particles 18 attached to its surface is θ1, the contact angle θ1 is related to the type of the resin material such as the cover 8 as shown in Table 2. For example, it is formed as a film having an angle of 80 ° or more.

The housing 1, the cover 8, the retainer ring 9, the shaping air ring 10, and the support arm 13 are previously treated with an acidic aqueous solution, a flame, a corona discharge,
By performing a pre-treatment such as a short wavelength ultraviolet treatment, an ozone oxidation treatment, and a silane coupling agent treatment, the water-repellent film 16 is formed.
And a strong adhesion can be obtained.

The rotary atomizing type coating machine according to the present embodiment has the above-described configuration. Next, the operation thereof will be described with reference to FIG. 1 and FIG.

First, when a high voltage is applied to each external electrode 14, each external electrode 14 and the rotary atomizing head 3 at the ground potential are applied.
, And each external electrode 14 and an object to be coated (not shown)
A static electric field region is formed by the lines of electric force.
Further, each of the external electrodes 14 has, for example, -60 to -120.
A high voltage of kV is applied, and the vicinity of the tip of each external electrode 14 is a negative ionization zone.

In this state, the paint is supplied to the rotary atomizing head 3 via the feed tube 4 by opening the paint valve 5 while rotating the rotary shaft 2 C and the rotary atomizing head 3 at a high speed by the air motor 2. You. At this time, the rotary atomization head 3
Supplied to the paint spraying surface 3B is spread radially outward from the paint discharge edge 3C by the centrifugal force generated by the rotation of the rotary atomizing head 3 and spreads out from the paint discharge edge 3C. And further atomized into particles from the liquid thread.

The atomized paint particles are narrowed toward the front of the rotary atomizing head 3 by shaping air that is jetted forward from the air jet port 11 of the shaping air ring 10 to form a spray pattern. You. Further, the paint particles are charged to a high voltage when passing through the ionization zone formed in front of each external electrode 14, and become charged paint particles. As a result, the charged paint particles fly toward the object connected to the ground and adhere to the surface of the object.

Next, the action of the water-repellent film 16 to prevent paint particles from adhering will be described with reference to FIGS.

First, the housing 1, the cover 8, the retainer ring 9, the shaping air ring 10, and the external electrode 14
The support arm 13 is charged to approximately the same potential as the charged paint particles by corona discharge of the external electrode 14. For this reason, an electric repulsion acts between the charged paint particles charged at a high voltage and the cover 8 or the like, so that the charged paint particles are hardly attached to the outer surface of the cover 8 or the like. However, actually, paint particles may adhere to the outer surface of the cover 8 or the like for the following reasons.

First, paint particles released from the paint discharge edge 3C may return to the cover 8 due to convection (air pumping phenomenon) of air generated near the coating machine due to shaping air or the like. Second, as described above, the charged paint particles having a small charge amount such as suspended particles are coated with the cover 8 of the coating machine having a high potential and the shaping air ring 1 as described above.
It is attracted to 0 mag. Third, the cover 8 or the like made of a resin material absorbs moisture in the air around the coating machine, and the cover 8
The charged paint particles are attracted to the cover 8 because the degree of insulation is lowered and approaches the ground potential.

In particular, in the painting booth for painting the body,
The temperature is set to 20 ° C. and the humidity is set to a high humidity of about 80 to 90%. This is to prevent paint particles in the air from floating and to ensure the safety of the painting operation.
As described above, since the coating apparatus performs the coating in the high-humidity coating booth, the cover 8 and the like easily absorb moisture in the air. In addition, in the case of using a paint containing water in the paint, such as a water-based paint, when the paint is sprayed by the painter, the moisture in the paint is dispersed and the humidity around the painter rapidly increases.
The insulating member of the coating machine is in a state of easily absorbing moisture. As a result, the paint particles easily adhere to the cover 8 and the like for the third reason.

Here, the housing 1, the cover 8, the retainer ring 9, the shaping air ring 10, and the support arm 13
Has the properties as shown in Table 1 below. The relative dielectric constant in Table 1 is 1 MHz.
For electromagnetic waves.

[0057]

[Table 1]

As described above, although the resin material used in the present embodiment can ensure the insulation between the air motor 2 and the outside and the outside, since the contact angle with water is 60 ° or less, it is easily stained by paint particles. Has properties.

Therefore, as shown in FIG. 4 as a comparative example, when the water-repellent film 16 is not provided on the surface of the cover 8 or the like, the degree of contamination by the paint particles after the painting operation is 100%. . The degree of dirt represents the ratio of the area where the paint particles adhere to the area of the outer surface of the coating machine.

The reason why the degree of contamination becomes extremely large is as follows. That is, the charged paint particles fly to the housing 1, the cover 8, the retainer ring 9, the shaping air ring 10, the support arm 13 of the external electrode 14, and the like.
It becomes the coating particles 19 and adheres. At this time, the surface of the cover 8 or the like has a high surface energy, and the contact angle θ2 between the surface of the cover 8 or the like and water is about 60 °.
The paint particles 19 adhered to the outer surface such as the like tend to connect with each other to form a continuous film 20. Then, since the continuous film 20 may be eventually connected to the ground, an electric field is formed between the external electrode 14 and the continuous film 20. As a result, the charged paint particles fly toward the continuous film 20, and the stains on the coating machine increase, making it impossible to continue painting.

On the other hand, in the present embodiment, the housing 1 made of a resin material, the cover 8, the retainer ring 9,
Shaping air ring 10, support arm 1 for external electrode 14
A water-repellent film 16 is provided on 3 and the like. As a result, as shown in Table 2, the degree of dirt can be suppressed to about 5% irrespective of the type of resin material such as the cover 8, and the same as PTFE (polytetrafluoroethylene) shown in Table 3 as a comparative example. The coating particles 18 can be prevented from adhering.

[0062]

[Table 2]

[0063]

[Table 3]

That is, the surface energy of the water-repellent film 16 is very low, and the contact angle θ 1 between the water-repellent film 16 and water is 80.
° or more. For this reason, as shown in FIG. 3, the paint particles 18 attached to the outer surface of the cover 8 and the like are raised almost hemispherically on the surface of the water-repellent film 16 and are repelled on the water-repellent film 16.

Therefore, the paint particles 1 adhered to the cover 8 and the like
In No. 8, since the continuous film 20 unlike the comparative example is not formed, the paint particles 18 are not connected to the ground,
Painting work can be reliably continued. Moreover, even if the paint particles 18 adhere to the outer surface of the cover 8 or the like, the paint particles 18 can be easily removed by the action of the water-repellent film 16 described above. Furthermore, continuous film 2
Since 0 is not formed, there is no occurrence of a stripped piece due to the coating film. Therefore, the reliability of the coating machine can be improved without impairing the coating quality of the object to be coated by the stripped pieces.

Thus, in the present embodiment, the water repellent film 16 is provided on the housing 1, the cover 8, the retainer ring 9, the shaping air ring 10, the support arm 13 of the external electrode 14, and the like. The adhesion of the particles 18 can be prevented, and the paint particles 18 can be easily washed. Therefore, the coating machine can be always kept in a clean state, and the coating operation can be continuously performed.

Also, since a polymethylsiloxane-based resin paint 17 is applied to the cover 8, the shaping air ring 10, and the support arms 13 of the external electrodes 14 to form the water-repellent film 16, the insulating resin such as the cover 8 is formed. Regardless of the type of material, the paint particles 18 can be repelled on the outer surface of the cover 8 or the like, and the adhesion of the paint particles 18 can be reliably prevented.

That is, the contact angle between the cover 8 and the water is 60 °.
Even when formed of the following insulating resin material, the coating particles 1 are formed by the water-repellent film 16 provided on the surface thereof.
You can play 8.

For this reason, PTF is used as a material for the cover 8 and the like.
Since a resin material such as POM or PET having higher mechanical strength than E can be used, the cover 8 and the like can be formed to be thin, and the coating machine can be reduced in weight and size. As a result, even when painting is performed by attaching the painting machine to a movable arm such as a robot or reciprocator, the painting machine can be moved quickly without impairing the functions of the robot and the like, and the painting work efficiency can be improved. Can be enhanced.
Further, since the cover 8 can be formed of a material having better mechanical workability than PTFE, the productivity of the cover 8 and the like can be improved, and the manufacturing cost can be reduced.

Since the water repellent film 16 has a contact angle θ1 with water of 80 ° or more, the water repellent film 16 is made of an insulating resin material in which the contact angle between the cover 8 and water is 60 ° or less. Even if the coating particles 18 adhere to the outer surface of the cover 8 or the like, the coating particles 18 protrude substantially hemispherically on the surface of the water-repellent film 16 and repel on the water-repellent film 16 so that the coating particles 1
8 can be prevented from adhering.

Further, since the water-repellent film 16 is provided on the support arm 13 supporting the external electrode 14, even when the charged paint particles having a small charge amount are attracted to the external electrode 14 and adhere to the support arm 13. The paint particles 18 can be repelled by the water repellent film 16. Thereby, the paint particles 18
Since it is possible to prevent the external electrode 14 from being connected to the ground by forming a continuous film, the coating operation can be reliably continued.

FIG. 5 shows a second embodiment of the present invention, which is characterized in that silica powder is added to the water-repellent film. In the present embodiment, the first
The same reference numerals are given to the same components as those in the embodiment, and the description thereof will be omitted.

Reference numeral 21 denotes a water-repellent film provided on the outer surface of the shaping air ring 10 or the like. As the water-repellent film 21, for example, a film obtained by adding a silica powder 23 to a polymethylsiloxane resin paint 22 is used. . The water-repellent film 21 is formed by applying a polymethylsiloxane-based resin paint 22 to which the silica powder 23 has been added to the outer surface of the shaping air ring 10, and the water-repellent film 16 according to the first embodiment is formed. Similarly, it has electrical insulation.

The contact angle of the water repellent film 21 with the paint particles 24 attached to the surface of the water repellent film 21 is θ 3 as shown in FIG.
Then, as shown in Table 4 below, the contact angle θ3 is formed as a film having a contact angle of, for example, about 95 to 110 ° depending on the amount of the silica powder 23 added. Thereby, the degree of dirt can be suppressed to 2% or less.

[0075]

[Table 4]

The addition amount of the silica powder is represented by the following formula 1 as a ratio of the weight of the silica powder 23 to the weight of the polymethylsiloxane-based resin coating material 22 composed of the resin and the thinner.

[0077]

(Equation 1)

Thus, the present embodiment having the above-described structure has substantially the same operation and effect as the first embodiment. However, in the present embodiment, since the water repellent film 21 is formed using the polymethylsiloxane-based resin paint 22 to which the silica powder 23 is added, the silica powder 23 reduces the contact angle θ3 between the water repellent film 21 and water to 90. ° or more. Therefore, the paint particles 2 on the water-repellent film 21
4 can be made more difficult to adhere, so that contamination of the shaping air ring 10 and the like can be more effectively prevented as compared with the first embodiment.

In each of the above embodiments, a case where an indirect charging type rotary atomizing type coating machine using an external electrode is used as an electrostatic coating apparatus has been described as an example. Without using, the air motor 2 and the rotary atomizing head 3 are formed of a conductive material, and the high voltage generator 15 is connected to the air motor 2 via a lead wire 31 shown by a two-dot chain line in FIG. The present invention may be applied to a direct charging type rotary atomizing type coating machine which directly charges a paint supplied through the rotary atomizing head 3 with a high voltage.

In each of the above embodiments, the housing 1, the cover 8, the retainer ring 9, the shaping air ring 10, and the support arm 13 are formed of an insulating resin material such as POM or PET. However, the present invention is not limited to this, and may be formed using another insulating resin material such as nylon 66, for example. Further, in each of the embodiments, the housing 1 and the like use an insulating resin material having a contact angle with water of 60 ° or less. However, a material having a contact angle with water larger than 60 ° may be used. . Further, a housing 1, a cover 8, a retainer ring 9, a shaping air ring 10,
The support arm 13 and the like are not limited to a resin material, but may be an insulating material such as a ceramic.

In the second embodiment, the silica powder 2
The water-repellent film 21 is formed using the polymethylsiloxane-based resin paint 22 to which the silica powder 2 is added.
A configuration may be adopted in which glass powder, which is one of the three, is added.
That is, since the glass powder is composed of almost the same components as the silica powder 23, the glass powder has the same water repellency as the silica powder 23.

Further, in each of the above embodiments, the case where a rotary atomizing type coating machine is used as an electrostatic coating device has been described as an example. However, an air atomizing type coating machine, a hydraulic atomizing type coating machine, and the like. And the like.

The present invention relates to, for example, JP-A-11-26.
As in the electrostatic coating apparatus described in US Pat.
The present invention may be applied to an electrostatic coating apparatus having an exchangeable feed unit connected to a paint supply source.
The invention may be applied to an electrostatic coating apparatus having a cartridge as a replaceable coating tank, such as an electrostatic coating apparatus described in Japanese Patent No. 62699 or the like. In this case, a water-repellent film may be formed on the outer surfaces of the feed unit and the cartridge constituting a part of the coating machine.

[0084]

As described in detail above, according to the first aspect of the present invention, since the water-repellent film is provided on the surface of the cover member made of an insulating material, the charged paint particles sprayed from the paint spraying means are covered with the cover member. The water-repellent film makes it possible to repel the charged paint particles even when the paint particles fly over the surface, and thus prevent the paint particles from adhering. This makes it possible to keep the electrostatic coating apparatus in a clean state at all times, to prevent a continuous film from being formed on the surface of the cover member by the attached paint particles, and to reliably continue coating. .

According to the second aspect of the present invention, since the cover member is formed of an insulating resin material having a contact angle with water of 60 ° or less, various insulating resins having high mechanical strength and light specific gravity are used. Material can be used, the coating equipment is lightweight,
The size can be reduced. Further, the paint particles flying to the cover member can be repelled by the water-repellent film, and the paint particles can be prevented from adhering to the surface of the cover member.

According to the third aspect of the present invention, since the water repellent film has a contact angle with water of 80 ° or more, paint particles adhering to the surface of the cover member are substantially hemispherical on the water repellent film. This makes it possible to prevent the paint particles from adhering, and to easily remove the paint particles from the water-repellent film.

According to the fourth aspect of the present invention, since silica powder or glass powder is added to the water-repellent film, the contact angle between the water-repellent film and water can be increased, and the water-repellent film can be used for coating. The particles can be repelled and the surface of the cover member can be kept clean.

According to the fifth aspect of the present invention, since the polymethylsiloxane-based resin coating is used for the water-repellent film, the contact angle between the water-repellent film and water can be made 80 ° or more. Since the projection is repelled in a substantially hemispherical shape on the water-repellent film, the surface of the cover member can be kept clean.

According to the sixth aspect of the present invention, the paint spraying means is provided at the front end of the air motor and rotatably provided by the air motor. The cover member is composed of a cover for accommodating the air motor, and a shaping air ring provided on the tip side of the cover so as to cover the outer peripheral side of the rotary atomizing head. A water-repellent film is provided on the surface of the cover and shaping air ring, so that even when paint particles sprayed from the rotary atomizing head fly to the cover and shaping air ring, the paint particles are repelled by the water-repellent film. Paint particles can be easily removed.

According to the seventh aspect of the present invention, since the water-repellent film is provided on the support arm supporting the external electrode, the charged paint particles having a small charge amount are attracted to the external electrode and adhere to the support arm. However, the paint particles can be repelled by the water-repellent film. As a result, it is possible to prevent the external electrode from being connected to the ground due to the continuous formation of the adhered paint particles, so that the painting operation can be reliably continued.

Further, according to the invention of claim 8, the high voltage applying means applies a high voltage to the air motor from the outside, and directly applies the high voltage to the paint before atomization supplied to the rotary atomizing head. Since the configuration is applied, the paint particles sprayed from the rotary atomizing head can be charged to a high voltage via the air motor and the rotary atomizing head and sprayed as charged paint particles toward the object to be coated. Even when the charged paint particles sprayed from the rotary atomizing head fly over the surface of the cover and the shaping air ring, the charged paint particles can be repelled by the water-repellent film.

[Brief description of the drawings]

FIG. 1 is a partially cutaway front view showing a rotary atomizing type coating machine according to a first embodiment of the present invention.

FIG. 2 is a sectional view showing a main part of the rotary atomizing type coating machine according to the first embodiment.

FIG. 3 is an enlarged cross-sectional view illustrating a main part of a cover, a shaping air ring, and a water-repellent film according to the first embodiment;

FIG. 4 is an enlarged sectional view of a main part, showing a cover and a shaping air ring according to a comparative example in an enlarged manner.

FIG. 5 is an enlarged cross-sectional view of a main part showing a cover, a shaping air ring, and a water-repellent film according to a second embodiment in an enlarged manner.

[Explanation of symbols]

 Reference Signs List 2 air motor 3 rotary atomizing head 8 cover 10 shaping air ring 13 support arm 14 external electrode 16, 21 water-repellent film 17, 22 polymethylsiloxane-based resin paint 23 silica powder

Claims (8)

[Claims] 1. A paint spraying means for spraying a supplied paint on an object to be coated, a cover member formed of an insulating material and accommodating the paint spraying means, and applying a high voltage to the paint particles sprayed from the paint spraying means. And a high-voltage applying means for applying the charged paint particles to the object to be coated on the surface of the cover member, wherein the cover member has an electrically insulating repellent for preventing the charged paint particles from adhering to the surface of the cover member. An electrostatic coating device comprising an aqueous film. 2. The cover member has a contact angle with water of 60 °.
The electrostatic coating device according to claim 1, wherein the electrostatic coating device is formed of the following insulating resin material. 3. The electrostatic coating apparatus according to claim 1, wherein the water-repellent film has a contact angle with water of 80 ° or more. 4. The electrostatic coating apparatus according to claim 1, wherein the water-repellent film is formed by adding silica powder or glass powder. 5. The electrostatic coating apparatus according to claim 1, wherein said water-repellent film is made of a polymethylsiloxane resin paint. 6. The paint spraying means comprises an air motor, and a rotary atomizing head positioned at a front end side of the air motor and rotatably provided by the air motor and having a tip serving as a paint discharge edge. The cover member includes a cover that houses the air motor, and a shaping air ring that is provided at the tip end of the cover so as to cover the outer peripheral side of the rotary atomizing head, and that ejects shaping air from an air outlet. 6. The electrostatic coating apparatus according to claim 1, wherein a water-repellent film is provided on surfaces of the cover and the shaping air ring located around the rotary atomizing head. 7. The high-voltage applying means includes a support arm located outside the cover and extending toward the vicinity of the rotary atomizing head, and spraying from the rotary atomizing head provided at a tip of the support arm. 7. The electrostatic coating apparatus according to claim 6, comprising an external electrode to which a high voltage is applied from outside to charge the paint particles to be charged, and a water-repellent film is provided on a surface of the support arm. 8. The high voltage applying means is configured to apply a high voltage from the outside to the air motor and directly apply the high voltage to the paint before atomization supplied to the rotary atomizing head. 7. The electrostatic coating device according to 6.