JP3266438B2 - Rotary atomizing head type coating equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rotary atomizing head type coating apparatus suitable for use in a direct charging type electrostatic coating apparatus which directly applies a high voltage.

[0002]

2. Description of the Related Art A generally known direct charging type rotary atomizing head type coating apparatus applies a high voltage to a rotary atomizing head via a rotary shaft, and paint particles emitted from the rotary atomizing head. Is charged, and the paint is caused to fly toward an object connected to the ground, so that the paint is applied to the object.

Here, the conventional direct charging type rotary atomizing head type coating apparatus detects that an overcurrent has flowed between the rotary atomizing head and the object to be coated in order to ensure safety. A device provided with an overcurrent detecting means is known, and such an electrostatic coating apparatus of this type will be described with reference to FIGS. 9 and 10. FIG.

[0004] In the drawing, reference numeral 1 denotes a painting booth, and a conveyor 2 is laid in the painting booth 1, and an object 3 to be grounded is placed on the conveyor 2. The object 3 is conveyed in the coating booth 1 by the conveyor 2, and a coating operation is performed during this time.

[0005] Reference numeral 4 denotes a main body of a direct charging type in which an air motor (not shown) for rotating and driving a metal rotary shaft is built in. A rotary shaft positioned at the tip side of the main body 4 has a rotary shaft. A rotary atomizing head 5 is mounted, and the coating machine main body 4 is connected to a color changing valve device 7 via a coating pipe 6. The color changing valve device 7 is connected to a paint tank (not shown), an air source, a thinner source, etc., and supplies paint from the paint tank to the rotary atomizing head 5 from the coating machine main body 4 through the paint pipe 6. Cleaning is performed by supplying thinner and air as necessary for color change or the like.

Here, the rotary atomizing head 5 is formed in a bell shape with a metal such as an aluminum material, and is provided at a tip of a rotary shaft (neither is shown) of an air motor built in the coating machine main body 4. A high voltage is applied to the rotary atomizing head 5 via a high voltage cable 10 and a rotating shaft, which will be described later. As described above, the rotary atomizing head 5 is rotated at a high speed by the air motor, and when the paint is supplied through the paint pipe 6 in a state where a high voltage is applied through the high voltage cable 10, the rotary atomizing head 5 is rotated. 5 sprays charged paint particles.

A high voltage generator 8 boosts the voltage output from the commercial power supply 9 to a high voltage of, for example, about -60 to -120 [kV], and a high voltage generator 10 paints the high voltage generated from the high voltage generator 8. High-voltage cables applied to the rotary atomizing head 5 via the machine body 4 are shown.
Is connected to the high voltage generator 8 and the other end is connected to the coating machine main body 4.

Reference numeral 11 denotes an overcurrent detector which detects an overcurrent flowing through the rotary atomizing head 5 via the high-voltage cable 10.

Reference numeral 12 denotes a cut-off switch provided between the high-voltage generator 8 and the commercial power supply 9;
Numeral 2 indicates that the overcurrent detector 11 is opened when the current flowing through the high-voltage cable 10 exceeds a predetermined current value.

In the electrostatic coating apparatus according to the prior art constructed as described above, the high voltage generated by the high voltage generator 8 is applied from the coating machine main body 4 to the rotary atomizing head 5 via the high voltage cable 10 or the like. You. On the other hand, by supplying the paint from the paint tank to the rotary atomizing head 5 through the color changing valve device 7 and the paint pipe 6, the paint is charged to the same potential as the applied high voltage. By discharging paint from the
Coating is performed by the force of the electrostatic field between the rotary atomizing head 5 and the substrate 3 at the ground potential. During this time, the high voltage generator 8, the high voltage cable 10, the rotary atomizing head 5, the object 3,
The ground forms an electrical loop through which current flows.

Further, the charged paint particles fly between the rotary atomizing head 5 of the coating machine main body 4 and the work 3 under the force of an electrostatic field, and fly due to air interposed therebetween. Is formed, and the electric resistance value R due to this air is
As a result, the electric charge stored for the insulating material, the bearing, the motor, and the individual capacities C of the rotary atomizing head 5 (these total capacities are considered to be several tens of pF) is discharged. Is prevented.

However, as shown in FIG. 10, when the rotary atomizing head 5 abnormally approaches or comes into contact with the workpiece 3 during coating, a short circuit accident or the like occurs. 3, the electric resistance value R becomes small, and the electric charge stored in the floating capacitance C of each component tends to discharge toward the object 3 at a stretch.

Although the current flowing from the high voltage generator 8 in a normal state is about 50 μA, when the electric charge stored in the stray capacitance C is discharged and sparks are generated at once, the energy reaches 1000 millijoules.

However, the current flowing through the loop is detected by the overcurrent detector 11, and when an overcurrent flows through this loop, the cutoff switch 12 is opened and the supply of the current to the high voltage generator 8 is stopped. . As a result, a short circuit accident due to abnormal approach or contact between the coating machine main body 4 and the workpiece 3 and a short circuit accident due to damage to a high-voltage cable and the like are prevented, and a fire due to paint ignition is prevented.

[0015]

By the way, in the above-mentioned prior art electrostatic coating apparatus, when the rotary atomizing head 5 and the workpiece 3 approach each other abnormally, the electric resistance value due to the air present between them is reduced. The cut-off switch 12 is opened when the current becomes smaller than the set value and flows to the overcurrent detector 11, but if the cut-off switch 12 does not operate or the operation is delayed, the rotation is stopped. Atomization head 5
There is a risk that a spark discharge occurs between the substrate and the object 3 and that the spark discharge causes a fire accident.

In particular, since the rotary atomizing head 5 according to the prior art is machined into a bell shape or a disk shape with a metal such as aluminum material, once the electric resistance value R becomes small and a spark occurs, it is stored in the stray capacitance C. Since most of the generated electric charges are instantaneously discharged, the discharge energy instantaneously increases. Therefore, it is very difficult to suppress the charge below the minimum ignition point of the organic solvent (thinner).

The present invention has been made in view of the above-mentioned problems of the prior art, and the present invention selects a material and a resistance value of the rotary atomizing head so that the rotary atomizing head can be positioned between the rotary atomizing head and the object to be coated. It is an object of the present invention to provide a rotary atomizing head type coating apparatus capable of reducing generated discharge energy and improving safety.

[0018]

A rotary atomizing head type coating apparatus employed in the first aspect of the present invention comprises a coating machine main body including an air motor for driving a rotary shaft to rotate, an outer peripheral surface and an inner peripheral surface. A rotary atomizing head having a bell shape or a disk shape, a base end side of which serves as an attachment portion to be attached to the rotating shaft, and a tip end serving as a paint discharge edge for spraying paint diffused from an inner peripheral surface; High voltage generating means for applying a high voltage to the atomizing head via the rotary shaft.

Then, in order to solve the above-mentioned problem,
A feature of the configuration adopted by the invention of claim 1 is that the rotary atomizing head is formed of an insulating resin material, and the outer peripheral surface of the rotary atomizing head has a paint discharge end from a mounting portion of the rotary atomizing head. the semiconductive film is formed over the edge is to the rear end of the semiconductive film has a structure which is contacted with the rotary shaft outer circumference.

The feature of the structure adopted by the invention of claim 2 is that
The rotary atomizing head is formed of an insulating resin material,
On the outer surface of the head, paint is discharged from the mounting part of the rotary atomizing head.
The semiconductive film is formed over the edges, very small between the rotary shaft outer circumference and the semiconductive layer to the mounting portion rear end position of the rotary atomizing head
The configuration is such that a gap is provided so as to be separated .

[0021] In the present invention of claim 3, together with the pre-Symbol providing an air insulation layer between the rotary shaft outer circumference and semiconductive layer, in that the provided conductor to the rear end of the semi-conductive layer.

According to a fourth aspect of the present invention, the resistance from the base end to the tip end of the rotary atomizing head is set in the range of 10 ⁷ to 10 ⁹ Ω.

[0023]

According to the present invention, the rotary atomizing head is made of an insulating resin material, and a semiconductive film is formed on the outer peripheral surface of the rotary atomizing head from the mounting portion to the paint discharge edge. ,
The stray capacitance of the components constituting the coating device can be a distribution capacitance distributed on the outer peripheral surface of the rotary atomizing head by resistance in each part of the semiconductive film formed on the outer peripheral surface of the rotary atomizing head, A plurality of L-shaped circuits to which the distributed capacitors are connected for the respective resistors are formed on the outer peripheral surface of the rotary atomizing head. Thereby, even if the rotary atomization head and the object to be coated approach each other abnormally, the electric charge stored from the distributed capacitance in the L-shaped circuit located at the paint discharge edge of the rotary atomization head is sequentially discharged. ,
Prevents the charge stored in the stray capacitance from discharging at once,
Discharge energy can be reduced. Moreover, since the floating capacitance connects a plurality of distributed capacitances in parallel, the capacitance of each distributed capacitance is reduced, the electrostatic energy at the time of discharge can be reduced, and each resistance due to the semiconductive film is reduced. And to form an L-shaped circuit from the distributed capacitance,
In the discharge of the L-type circuit, the discharge speed of the electric charge due to the time constant can be delayed, and the current value discharged from the distributed capacitance can be suppressed. Also, the rear end of the semiconductive film is
High voltage generated by high voltage generator
Atomizing head spinning through semi-conductive film with voltage applied from rotating shaft
It can be applied to the emission edge.

[0024] As the invention of claim 2, the Rukoto is separated with a small gap between the rotary shaft outer circumference and the semiconductive layer, the resistance value of the semiconductive layer and the resistance value of the air insulating layer The floating resistance of the components that make up the coating equipment is divided into distributed capacities by this resistance value, and stored in each distributed capacity, even if the rotary atomizing head and the object to be coated approach abnormally. Since the discharged charges are sequentially discharged, the discharge energy can be further reduced.

By forming an air insulating layer and a conductor between the semiconductive film and the outer periphery of the rotating shaft, the resistance value of the semiconductive film and the resistance of the air insulating layer can be improved. The stray capacitance can be divided into distributed capacitances by this resistance value, and the charges stored in each distributed capacitance can be sequentially discharged even if the rotating atomization head and the object to be coated approach abnormally. As a result, the discharge energy can be further reduced. Furthermore, since the conductor is provided at the rear end of the semiconductive film, the resistance value of the air insulating layer between the conductor and the outer periphery of the rotating shaft can be easily and accurately adjusted, and the resistance value is kept constant. be able to.

According to a fourth aspect of the present invention, the resistance from the base end to the tip end of the rotary atomizing head is 10 ⁷ to 10 ⁹ Ω.
The high voltage applied from the high voltage generating means can be increased by setting the value within the range.

[0027]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. In the embodiments, the same components as those of the above-described conventional technology are denoted by the same reference numerals, and description thereof will be omitted.

First, FIGS. 1 to 4 show a first embodiment of the present invention.
The following shows an example.

In the figure, reference numeral 21 denotes an electrostatic coating machine according to the present embodiment,
Reference numeral 22 denotes a coating machine main body which forms a housing of the electrostatic coating machine 21. An annular motor housing portion 22A and a device housing portion 22B for housing a high-voltage generator 46 to be described later are provided at the distal end side of the coating machine main body 22. Are integrally formed, and a mounting bracket (both not shown) is provided on the base end side to be mounted on a reciprocator or the like. The coating machine body 2
The outer peripheral side of 2 is covered with a main body cover 23 formed in a tubular shape with an insulating resin material.

Reference numeral 24 denotes a motor housing 22 of the coating machine main body 22.
1A shows a metal turbine type air motor mounted on the shaft A. The air motor 24 has a shaft hole 25 formed in the axial direction.
And air bearings 26 provided so as to surround the shaft hole 25, and an air turbine 27 provided at the base end side of the shaft hole 25. Compressed air is supplied to each of the air bearings 26 from a bearing air supply passage 28 and to the air turbine 27 from a drive air supply passage 29.

Reference numeral 30 denotes a hollow cylindrical rotary shaft made of a metal material inserted into the shaft hole 25. The rotary shaft 30 has a base end fixed to the air turbine 27 and a tip end protruding outside the air motor 24. . The rotating shaft 30 is driven by the air turbine 27 to rotate at high speed.

Reference numeral 31 denotes a bell-shaped rotary atomizing head according to the present embodiment in which a semiconductive film 34 described later is formed on the outer peripheral surface of the rotary shaft 30 and fixed to the tip end of the rotary shaft 30 outside the air motor 24. The rotary atomizing head 31 is made of an insulating resin material (for example, polyether sulfone (PES), polyphenylene sulfide (PPS), polyetherimide (PE).
I), polyetheretherketone (PEEK) or the like, and the base end is attached to the rotary shaft 30 with a rim 32 provided integrally screwed in the middle in the axial direction as shown in FIG. And the outer peripheral surface 31
B expands like a bosh from the mounting portion 31A toward the tip, the inner peripheral surface 31C expands in a stepped manner, the front side becomes a paint smooth surface, and the distal side diffuses through the inner peripheral surface 31C. A paint discharge edge 31D for spraying paint is provided.

Numeral 33 denotes a hub member which is screwed and provided on the inner peripheral surface 31C of the rotary atomizing head 31 and is formed of a resin material together with the rotary atomizing head 31.
The rear side is a convex conical paint supply surface 33A on which paint and thinner as a cleaning solvent are selectively supplied from a feed tube 39 described later, and the outer peripheral surface is provided with the paint and cleaning solvent from the paint supply surface 33A. A large number of first hub holes 33B are provided (only two are shown) for guiding the thinner to the paint discharge edge 31D side of the rotary atomizing head 31 and a central portion for supplying thinner to the front side. Two hub holes 33C are formed.

Numeral 34 denotes a semiconductive film formed on the outer peripheral surface 31B of the rotary atomizing head by a coating means or the like.
Is formed of, for example, polyester, epoxy, fluororesin or the like obtained by kneading conductive fibers, and the semiconductive film 34 has an outer surface mounting portion 3 as shown in FIG.
The outer peripheral surface 31B is formed from 1A to the paint discharge edge 31D. The thickness of the semi-conductive film 34 is different from the thickness of the mounting portion 31A in the rotary atomizing head 31 according to the present embodiment.
From the paint discharge edge 31D to 10 ⁷ to 10 ⁹
It is set to be in the range of Ω.

Here, the resistance value of the semiconductive film 34 is set by the applied high voltage. For example, when the high voltage is 60 kV or less, the resistance value is set so as to be 10 ⁷ to 10 ⁸ Ω. When the voltage is 60 kV or more, 10 ⁸
The resistance value is set so as to be 〜１０10 ⁹ Ω.

In the rotary atomizing head 31 according to the present embodiment, as shown in FIG.
In the vicinity, the rear end 34A of the semiconductive film 34 is formed up to a position where the rear end 34A comes into contact with the outer periphery of the rotating shaft 30. Therefore, the high voltage supplied from the high voltage Through the rotary atomizing head 31, where the voltage is directly applied to the semiconductive film 34, and a high voltage is supplied from the semiconductive film 34 to the paint discharge edge 31 </ b> D. I have.

Numeral 35 denotes a shaping air ring which is provided on the tip side of the coating machine main body 22 so as to surround the axially intermediate portion of the outer peripheral surface 31B of the rotary atomizing head 31 and is formed of a resin material. An outer air nozzle 35A and an inner air nozzle 35B are provided. The inner air nozzle 35B is screwed to the main body cover 23, and the outer air nozzle 35A is tightly attached to the coating machine main body 22. An annular air ejection hole 35C is formed at the tip end side of the shaping air ring 35, and the air from the shaping air supply passage 36 is supplied to the air ejection hole 35C via the air chambers 37, 38 and the like. ,
This air is ejected as shaping air to the vicinity of the paint discharge edge 31D of the rotary atomizing head 31, and a paint spray pattern sprayed from the rotary atomizing head 31 is formed into a circular shape.

Reference numeral 39 denotes a feed tube provided coaxially within the rotary shaft 30. The feed tube 39 has a double tube structure composed of an outer tube 40 and an inner tube 41, and will be described later in the middle of the inner tube 41. A valve seat 41A on which a valve body 44C of the paint valve 44 is separated and seated is formed integrally.

Reference numeral 42 denotes a paint passage formed in the inner cylinder 41. The paint passage 42 has a base end connected to the color changing valve device 7 through the paint pipe 6 and a tip end provided with a paint supply for the hub member 33. It is open toward the surface 33A. The paint passage 42 discharges paint contained therein toward the hub member 33 when a paint valve 44 provided in the middle thereof opens and closes.

Reference numeral 43 denotes a solvent passage formed between the outer cylinder 40 and the inner cylinder 41. The solvent passage 43 has a base end connected to a cleaning valve device (both not shown) via a solvent supply pipe. The inner cylinder 41 is connected and the distal end side is open toward the distal end 41B side of the inner cylinder 41. The solvent passage 43 opens and closes a tip-side cleaning valve 45, which will be described later, provided in the middle of the solvent passage 43, so that the thinner supplied from outside can be supplied to the tip 41B of the inner cylinder 41.
To clean the front color paint adhered to the tip 41B.

Reference numeral 44 denotes a normally closed paint valve.
Is an actuator 44A provided on the coating machine main body 22.
A valve shaft 44B having a proximal end connected to the actuator 44A and a distal end inserted through the inner cylinder 41;
And a valve body 44C which is detachably seated on the valve seat 41A of the inner cylinder 41. The paint valve 44 is normally seated on the valve seat 41A and closed, and when external control air is supplied to and discharged from the actuator 44A, the valve shaft 44B is contracted and the valve body 44C is connected to the valve of the inner cylinder 41. Seat 41A
And the paint passage 42 is opened.

Reference numeral 45 denotes a normally-closed front-end cleaning valve.
The distal-side cleaning valve 45 is provided with an actuator 45A provided on the coating machine main body 22 and a proximal side provided with the actuator 45A.
And a valve shaft 45B having a distal end inserted into the solvent passage 43, and a valve body 45C provided at the distal end of the valve shaft 45B and opening and closing the middle of the solvent passage 43. The tip side cleaning valve 45 is always in the solvent passage 43.
Is closed, and the valve is opened by supplying control air from the outside to communicate between the cleaning valve device (not shown) and the solvent passage 43.

Reference numeral 46 denotes a device housing portion 22B of the coating machine main body 22.
1 shows a high-voltage generator as high-voltage generating means housed in a high-voltage generator 46. The high-voltage generator 46 is composed of a high-voltage generating circuit composed of a multiplying voltage circuit and a high-voltage resistor for safety assurance. Z). The input side of the high-voltage generator 46 is connected to a high-voltage power supply (both not shown) via a lead wire, and the output side is connected to the air motor 24 via an electrode plate 46A. The high voltage generator 46 boosts the voltage supplied from the high voltage power supply to a predetermined high voltage, and applies the high voltage from the air motor 24 to the rotary atomizing head 31 via the rotary shaft 30.

The electrostatic coating machine 21 according to the present embodiment is configured as described above. Next, the operation thereof will be described.

In the electrostatic coating machine 21 of this embodiment, in the coating operation, the rotary atomizing head 31 is rotated at a high speed by the air motor 24 in the same manner as in the electrostatic coating apparatus of the prior art. With high voltage applied,
By opening the paint valve 44, the paint in the paint tank is supplied to the rotary atomizing head 31 through the paint passage 42, and the paint particles charged and atomized by the rotary atomizing head 31 are discharged by the electrostatic field. Apply to the substrate with force.

In this embodiment, the high voltage supplied from the high voltage generator 46 is supplied to the air motor 24,
It is applied to the semiconductive film 34 of the rotary atomizing head 31 via the rotary shaft 30. At this time, the semiconductive film 34 formed on the outer peripheral surface 31B of the rotary atomizing head 31 further has a rear end 34A.
Is in contact with the rotating shaft 30, the semiconductive film 34 is directly charged and applied to the paint discharge edge 31D.

When the rotary atomizing head 31 is rotated at a high speed, the coating material supplied through the coating channel 42 by opening the coating valve 44 is rotated by the rotation of the rotary atomizing head 31. Spreads on the peripheral surface 31C, and the paint discharge edge 31
D sprays radially outward. At this time, since a high voltage is applied to the paint discharge edge 31D, the discharged paint particles can be charged. Further, the discharged charged paint particles are formed as a paint spray pattern by shaping air ejected from a shaping air ring 35, and fly by applying the force of an electrostatic field formed between the paint and the object. The paint is applied to the paint.

However, in the electrostatic coating machine 21 of this embodiment, unlike the rotary atomizing head 5 of the prior art, the rotary atomizing head 31 itself is formed of an insulating resin material, and then the outer peripheral surface 31 is formed.
By giving a large resistance value to the semiconductive film 34 on which B is formed, as shown in FIG. 4, the coating machine main body 22, the main body cover 23, and the bearing 26 are formed of insulating resin.
And the stray capacitances C of the components constituting the coating device such as the motor 24 are individually distributed on the outer peripheral surface 31B by the resistance R0 of each part of the semiconductive film 34 formed on the outer peripheral surface 31B of the rotary atomizing head 31. And a plurality of L-type circuits can be considered to be constituted by the respective distributed capacitors C0 and the resistors R0.

Here, when the electrostatic coating machine 21 abnormally approaches the object to be coated, the electric resistance value R due to air between the rotary atomizing head 31 and the object to be coated becomes small, and The charge stored in the stray capacitance C by each of the components 21 tries to discharge at once.

However, in this embodiment, a plurality of L-shaped circuits are formed by the distributed capacitance C0 in which the stray capacitance C is distributed on the outer peripheral surface 31B of the rotary atomizing head 31 and the resistance R0. The discharge is sequentially performed from the distributed capacitance C0 in the L-shaped circuit located on the 31D side. At this time, the amount of charge stored in each distributed capacitance C0 is reduced, and the discharge is performed according to the time constant of C0 and R0 constituting the L-shaped circuit. The time can be suppressed, and the charge stored in the floating capacitance C can be prevented from being discharged at a stretch. In addition, the current value at the time of discharge can be suppressed to a level that is less than the ignition energy.

As a result, the discharge energy generated between the electrostatic coating machine 21 and the object to be coated can be suppressed to a small value, so that energy enough to ignite the paint can be prevented from being released, and a fire accident due to spark discharge can be prevented. Can be prevented. Then, the safety of the electrostatic coating machine 21 can be reliably increased, and the reliability can be improved.

Next, FIG. 5 shows a second embodiment according to the present invention. In this embodiment, the same reference numerals are given to the same components as those in the above-described first embodiment, and description thereof will be given. It shall be omitted.

However, the feature of this embodiment is that the rotary atomizing head 3
1 at the rear end position of the mounting portion 31A, the semiconductive film 51
The distance between the rear end 51A and the outer periphery of the rotating shaft 30 is, for example, 2 mm.
That is, the air insulating layer 52 having the gap Δd of about 1 mm or less, preferably about 1 mm or less.

In this embodiment, the air insulating layer 52 having a gap Δd of about 1 mm or less is formed between the semiconductive film 51 and the outer peripheral surface of the rotating shaft 30. Air discharge is performed in the layer 52, and a high voltage on the rotating shaft 30 side is applied to the semiconductive film 51 through the air insulating layer 52. For this reason, the resistance value on the outer peripheral surface 31B of the rotary atomizing head 31 is the sum of the resistance value of the semiconductive film 51 and the air resistance value of the air insulating layer 52, and as shown in FIG. The resistance value of the resistor R0 forming the pattern circuit can be increased. This makes it possible to increase the time constant of each L-shaped circuit, suppress the discharge time of the L-shaped circuit that sequentially discharges from the paint discharge edge 31D side, and reduce the current value. As a result,
The resistance value of the outer peripheral surface 31B of the rotary atomizing head 31 according to the present embodiment can be larger than the resistance value of only the semiconductive film 34 according to the first embodiment, and the discharge energy generated instantaneously is reduced to the first value. The embodiment can be made smaller than in the embodiment, and a fire accident in spark discharge can be prevented. Further, by adjusting the gap Δd of the air insulating layer 52, the resistance value can be easily set.

Next, FIG. 6 shows a third embodiment according to the present invention. In this embodiment, the same components as those in the above-described first embodiment are denoted by the same reference numerals, and description thereof is omitted. It shall be.

However, the feature of this embodiment is that the rotary atomizing head 3
1 at the rear end position of the mounting portion 31A, the semiconductive film 61
An air insulating layer 62 having a gap Δd of about 2 mm or less, preferably 1 mm or less, between the rear end 61A and the outer periphery of the rotating shaft 30 and a metal layer 63 serving as a good conductor are formed.

Although the rotary atomizing head 31 having the above-described structure can provide the same function and effect as that of the first embodiment described above, in this embodiment, the air insulating layer 6 is used.
When adjusting the gap Δd of 2, the metal layer 63 can surely adjust the gap Δd, and the air resistance of the air insulating layer 62 can be easily set. Then, the resistance value of the outer peripheral surface 31B of the rotary atomizing head 31 (the resistance value of the semiconductive film 61 and the air resistance value of the air insulating layer 62) is smaller than the resistance value of the semiconductive film 34 according to the first embodiment. (Total) is easy to manage, and this resistance value can be appropriately maintained.

FIG. 7 shows a fourth embodiment according to the present invention. The feature of this embodiment is that a disk type is used for the rotary atomizing head. Note that, in this embodiment, the first
The same reference numerals are given to the same components as those of the embodiment, and the description thereof will be omitted.

In the drawing, reference numeral 71 denotes a disk-type rotary atomizing head formed of an insulating resin material according to the present embodiment. The disk-type rotary atomizing head 71 has a base end attached to a rotary shaft 73 of an air motor 72. The outer peripheral surface 71B increases in diameter from the mounting portion 71A toward the distal end, the inner peripheral surface 71C becomes a paint smooth surface, and the distal end side is the inner peripheral surface 71C.
Is a paint discharge edge 71D for spraying the paint diffused through. Also, a large number of grooves 71E, 71E,... Are formed in the paint discharge edge 71D. Further, the rotary atomizing head 71 fixes the mounting portion 71A to the rotary shaft 73 with a screw 74 screwed on the axis of the rotary shaft 73.

Reference numeral 75 denotes a semiconductive film.
5 is a paint discharge edge 7 from the mounting portion 71A of the rotary atomizing head 71.
The outer peripheral surface 71B is formed over 1D. And
The rear end 75A of the semiconductive film 75 is electrically connected to the rotating shaft 73 via a screw 74.

Further, reference numeral 76 denotes an inner peripheral surface 7 of the rotary atomizing head 71.
1C shows a paint supply pipe for supplying paint to 1C.

In the rotary atomizing head 71 thus configured, the rotary atomizing head 71 is also rotated at a high speed following the rotation of the rotary shaft 73, and a high voltage from a high voltage generator (not shown) is applied to the rotary shaft. It is applied to the rotary atomizing head 71 via 73. Further, the paint supplied to the inner peripheral surface 71C of the rotary atomizing head 71 is diffused from the inner peripheral surface 71C toward the paint discharge edge 71D by centrifugal force, and each of the paints engraved on the paint discharge edge 71D. The paint is reliably sprayed as the paint particles by the concave groove 71E. At this time, these paint particles are directly charged by the high voltage applied to the paint discharge edge 71D via the semiconductive film 75.

Then, the paint particles released from the paint release edge 71D can be applied on the tip side of the semiconductive film 75, so that the electrostatic coating can be performed reliably.

Further, as described in the first embodiment, even when the object to be coated abnormally approaches, the coating is performed by the resistance value of the semiconductive film 75 covering the outer peripheral surface 71B of the rotary atomizing head 71. By distributing the stray capacitance of the components constituting the device together with the resistance as a distributed capacitance and discharging sequentially from the charge stored in the distributed capacitance on the paint discharge edge 71D side, the current value that was discharged at once is suppressed, and the discharge energy is reduced. And fire accidents can be reliably prevented.

In the fourth embodiment, as in the second embodiment, the rear end 75A of the semiconductive film 75 is used.
A gap may be provided between the rotating shaft 73 (screw 74) and an air insulating layer may be formed, or a conductor may be provided at the rear end 75A of the semiconductive film 75 as in the third embodiment. Good.

In each of the above embodiments, the high voltage cable 10, the overcurrent detector 11, and the cutoff switch 12 have been described as being omitted. However, the present invention is not limited to this.
As shown in a modified example of the above, the high voltage generator 8 may be provided outside the coating machine main body 22, and the overcurrent detector 11 and the cutoff switch 12 as overcurrent detection means may be provided. Spark discharge can be prevented.

[0067]

As described above in detail, according to the first aspect of the present invention, the rotary atomizing head is formed of an insulating resin material,
Since a semiconductive film is formed on the outer peripheral surface of the rotary atomizing head from the mounting portion to the paint discharge edge, the floating capacitance of the components constituting the coating apparatus is distributed by the resistance in each part of the semiconductive film. Even when the rotary atomizing head and the object to be coated approach each other abnormally, the charges stored in the distribution capacity located on the paint discharge edge side are sequentially discharged, so the charges stored in the floating capacity are Discharge at once can be suppressed, and discharge energy can be suppressed low. As a result, the emission current is limited to prevent the energy that can ignite the paint from being released at once, so that spark discharge can be reliably prevented and safety can be improved. Also, the rear end of the semiconductive film
Because it was brought into contact with the outer periphery of the rotating shaft, the
High voltage from the rotating shaft through the semiconductive film
It can be applied to the paint discharge edge.

According to a second aspect of the present invention, at the rear end position of the mounting portion of the rotary atomizing head, the space between the semiconductive film and the outer periphery of the rotary shaft is provided.
The resistance value is the sum of the resistance value of the semiconductive film and the air resistance of the fine gap , and the floating capacitance of the components constituting the coating apparatus is reduced by each part of the semiconductive film. In the case where the rotating atomization head and the object to be coated approach each other abnormally, the charges accumulated from the distribution capacitor located on the paint discharge edge side are sequentially discharged, so that the floating capacity can be obtained. It is possible to prevent the stored electric charge from being discharged at once, thereby preventing spark discharge and improving safety. In addition, by adjusting the minute gap between the rear end of the semiconductive film and the rotating shaft, the resistance value formed therebetween can be easily set.

According to the third aspect of the present invention, at the rear end position of the mounting portion of the rotary atomizing head, an air insulating layer and a conductor are formed between the semiconductive film and the outer periphery of the rotating shaft. The resistance value is the sum of the resistance value of the semiconductive film and the resistance value of the air insulating layer, and the stray capacitance of the components constituting the coating apparatus can be made the distributed capacitance by the resistance in each part of the semiconductive film, Even when the rotating atomization head and the object are abnormally close to each other, the stored charge is discharged sequentially from the distribution capacity located on the paint discharge edge side, so that the charge stored in the floating capacity is prevented from being discharged at once. Thus, the discharge energy can be kept low. Thus, safety can be enhanced even when the rotating atomization head and the object to be coated approach abnormally. Further, the gap between the air insulating layers can be managed by the conductor provided at the rear end of the semiconductive film, and the air resistance of the air insulating layer can be kept constant.

According to the fourth aspect of the present invention, the resistance from the base end to the tip end of the rotary atomizing head is 10 ⁷ to 10 ⁹ Ω.
The high voltage applied from the high voltage generating means can be increased by setting the value within the range.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view showing a main part of an electrostatic coating machine according to a first embodiment.

FIG. 2 is an enlarged longitudinal sectional view showing a bell-shaped rotary atomizing head and a rotary shaft in FIG. 1;

FIG. 3 is a longitudinal sectional view of an essential part showing an enlarged a portion in FIG. 2;

FIG. 4 is an explanatory diagram showing a relationship between a rotary atomization head and a stray capacitance in the first embodiment.

FIG. 5 is a longitudinal sectional view showing the second embodiment, viewed from the same position as in FIG. 3;

FIG. 6 is a longitudinal sectional view showing the third embodiment, viewed from the same position as in FIG. 3;

FIG. 7 is a longitudinal sectional view showing a disk type rotary atomizing head and the like according to a fourth embodiment.

FIG. 8 is a configuration diagram showing a modification of the electrostatic coating device according to the first embodiment.

FIG. 9 is a system diagram of a conventional electrostatic coating apparatus.

FIG. 10 is an explanatory diagram showing a relationship between a rotary atomization head and a stray capacitance according to the related art.

[Explanation of symbols]

 Reference Signs List 21 electrostatic coating machine 22 coating machine main body 24 air motor 30 rotating shaft 31, 71 rotating atomizing head 31A, 71A mounting part 31D, 71D paint discharging edge 34, 51, 61, 75 semiconductive film 34A, 51A, 61A, 75A rear end 46 high voltage generator (high voltage generating means) 52,62 air insulation layer 63 metal layer (conductor)

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) B05B 5/00-5/10 B05D 1/04

Claims (4)

(57) [Claims] 1. A coating machine main body having a built-in air motor for rotatingly driving a rotary shaft, and a bell-shaped or disk-shaped one having an outer peripheral surface and an inner peripheral surface, and a base end side serving as a mounting portion mounted on the rotary shaft. Along with the rotary atomizing head whose tip is a paint discharging edge for spraying paint diffused from the inner peripheral surface, and high voltage generating means for applying a high voltage to the rotary atomizing head via the rotating shaft. in consisting rotary atomizing head type coating machine, pre-Symbol rotary atomizing head is formed of an insulating resin material, on the outer peripheral surface of the rotary atomizing head half toward paint releasing edges of the mounting portion of the rotary atomizing head A rotary atomizing head type coating apparatus, wherein a conductive film is formed and a rear end of the semiconductive film is brought into contact with an outer periphery of the rotating shaft. 2. A built-in air motor for rotating a rotating shaft.
With a bell-shaped body consisting of
Or disk type, with the proximal end attached to the rotating shaft.
And the tip diffuses from the inner peripheral surface.
A rotary atomizing head serving as a paint discharge edge for spraying a material;
High voltage for applying high voltage to the atomization head via the rotating shaft
In the rotary atomizing head type coating apparatus comprising a generating means, the rotary atomizing head is formed of an insulating resin material.
Paint is released from the mounting part of the rotary atomizing head on the outer peripheral surface of the atomizing head.
The semiconductive film is formed over the Extension end edges, the mounting portion rear end position of the rotary atomizing head to separate between the rotary shaft outer circumference and the rear end of the semiconductive film having a minute gap structure Specially
Rotary atomizing head type coating apparatus according to symptoms. With wherein prior Symbol providing an air insulation layer between the rotary shaft outer circumference and semiconductive film, the rotation of said formed by providing a conductor on the rear end of the semiconductive film according to claim 2, wherein the atomizing head Mold coating equipment. 4. A resistance from the base end side of the rotary atomizing head to the tip side, 10 ⁷ to 10 ⁹ Omega claim 1 comprising set within a range of, 2 or 3 rotation according atomizing head Mold coating equipment.