JP3266440B2 - 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 coating an object to be coated such as a car body or steel furniture.

[0002]

2. Description of the Related Art A rotary atomizing head type coating apparatus of a direct charging type which is generally known has a rotary atomizing head formed of a conductive metal material, and a high voltage is applied to the rotary atomizing head via a rotating shaft. Apply
The paint particles emitted from the rotary atomizing head are charged, and the paint is caused to fly toward a coating object connected to the ground, and is applied to the coating 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 a rotary atomizing head type electrostatic coating device of this type will be described with reference to FIGS. 6 and 7. 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 direct charging type coating machine main body having a built-in air motor (not shown) for rotationally driving a metal rotary shaft. The rotary shaft located at the tip end side of the coating machine main body 4 has a rotary fog. A coating head 5 is attached, 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 includes a paint tank (not shown), an air source,
Connected to a thinner source and the like, paint from the paint tank is supplied from the painter body 4 to the rotary atomizing head 5 through the paint pipe 6, and thinner and air are supplied as needed for color change, etc., for cleaning. It is supposed to do.

Here, the rotary atomizing head 5 is formed in a bell shape from a metal such as aluminum, and a high voltage is applied thereto through 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. From 5, charged paint particles charged to a high voltage are sprayed.

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;
Reference numeral 2 denotes an opening when the current flowing through the high-voltage cable 10 detected by the overcurrent detector 11 becomes equal to or more than a predetermined current value.

[0010] In the rotary atomizing head type electrostatic coating apparatus according to the prior art configured as described above, the high voltage generated by the high voltage generator 8 is applied to the coating machine body 4 via the high voltage cable 10 or the like.
To the rotary atomizing head 5. 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 spraying the coating material from above, the electrostatic spraying force is applied between the rotary atomizing head 5 and the object 3 at the ground potential to apply the coating. During this time,
An electric loop is formed by the high-voltage generator 8, the high-voltage cable 10, the rotary atomizing head 5, the workpiece 3, and the ground, and a current flows through the loop.

Further, between the rotary atomizing head 5 of the coating machine main body 4 and the object 3 to be coated, as shown in FIG. 7 , charged paint particles fly by suction under the force of an electrostatic field. A predetermined electric resistance value R is formed by the air interposed therebetween, and the electric resistance value R by the air causes the individual capacities of the insulating material, the bearings and the motor, and the rotary atomizing head 5 and the like constituting the coating machine main body 4. C (these total capacities are considered to be of the order of tens of PF) prevent the stored charge from being discharged.

However, during the painting, the rotary atomizing head 5 is
When a short circuit accident or the like that abnormally approaches or comes into contact with the object occurs, the electric resistance value R between the rotary atomizing head 5 and the workpiece 3 becomes small, and the electric charge stored in the stray capacitance C of each component is reduced. Attempts 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 to stop the current supply to the high voltage generator 8. . 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]

In the above-described conventional rotary atomizing head type electrostatic coating apparatus, the rotary atomizing head 5 and the work 3 are abnormally close to each other. The shut-off switch 12 is opened when the resistance value R decreases and a current equal to or more than the set value flows to the overcurrent detector 11. However, the shut-off switch 12 does not operate or an operation delay occurs. In such a case, a spark discharge is generated between the rotary atomizing head 5 and the object 3 to be coated, and there is a possibility that a fire accident may be caused by the spark discharge.

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

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems of the prior art, and has been made to reduce the discharge energy generated between the rotary atomizing head and the object to be coated, thereby improving the safety. It is intended to provide a chemical coating device.

[0018]

According to a first aspect of the present invention, there is provided a rotary atomizing head type coating apparatus, comprising: a rotating shaft rotated by an air motor; and a tip end side of the rotating shaft. And a rotary atomizing head formed of an insulating resin material and having an outer peripheral side serving as a paint discharging edge, and a rotary atomizing head formed of an insulating resin material and directed toward the vicinity of the paint discharging edge of the rotary atomizing head. Stretch and form paint spray patterns
Aerin that blows out shaping air
And grayed, provided in the shaping air ring, the tip end side is extended toward the vicinity of the paint releasing edges of the rotary atomizing head,
It comprises a corona pin connected to a high-voltage generator, and a high-resistance element connected between the corona pin and the high-voltage generator .

Further, the invention according to claim 2 is characterized in that
A sub air chamber is formed in the ring, and a corona pin is provided so as to protrude from the tip of the shaping air ring.
The resistance element is housed in the sub air chamber.
Have .

[0020]

According to the structure of the first aspect of the present invention, the rotary atomizing head,
Forming shaping air ring etc. with insulating resin material,
The shaping air ring is connected to a high voltage generator.
A corona pin and a high voltage generator
By connecting and providing a high-resistance element between the high-voltage generator and the high-voltage cable, even if the rotary atomizing head or shaping air ring abnormally approaches the workpiece, Prevents the stored charge from being discharged to the object to be coated via the corona pin, and secures sufficient safety only by discharging the extremely small charge charged to the corona pin at the tip side of the high-resistance element. Can be . Also, Sha
Ping air ring is said to eject shaping air
Can be used as a holder for corona pins in addition to functions
it can.

According to the second aspect of the present invention , the high resistance element is
Since it was housed in the sub air chamber,
Corona pins can be mounted using ping air rings.
Capable of holding a shaping air ring on each corona pin
Tools and protective covers for each high-resistance element.
Wear.

[0022]

BRIEF DESCRIPTION OF THE PREFERRED embodiment of the present invention in FIGS. 1-5. In the embodiments, the same components as those in the above-described conventional technology are denoted by the same reference numerals, and description thereof will be omitted.

In the figure, reference numeral 21 denotes an electrostatic coating machine according to the present embodiment,
Numeral 22 indicates a housing of the electrostatic coating machine 21, respectively.
The housing 22 is made of an insulating resin material (for example, polyethylene terephthalate (PET), polyacetal (P
OM), polyamide (PA), polyethylene (PE),
A cylindrical portion 2 made of polypropylene (PP) or the like and having a bottomed shape and extending in the axial direction from the outer periphery of the base portion 22A.
Inside 2B is a motor accommodating portion 22C that accommodates an air motor 23 described later. Further, a female screw portion 22D is formed on the inner periphery of the distal end side of the cylindrical portion 22B.

Reference numeral 23 denotes a motor housing portion 22 of the housing 22.
C shows a turbine-type air motor attached to a motor case 23. The air motor 23 includes a motor case 23A formed of a conductive metal material in a cylindrical shape, and air bearings 23B and 23B rotatably supporting a rotating shaft 27 described later. , An air turbine 23C positioned on the base end side of the motor case 23A and fixed to the outer periphery of the rotating shaft 27. The motor case 23A is connected to a high voltage via a connection terminal 39 and a high-voltage cable 10 described later. It is connected to a voltage generator 8.

Reference numeral 24 denotes a fixing ring provided on the outer periphery of the distal end side of the air motor 23. The fixing ring 24 has a plurality of (two shown) air holes 24A, 24A penetrating in the axial direction. ing. Also, the fixing ring 24
Is screwed into the female screw portion 22D of the housing 22 so that the motor case 23A is
And a main air chamber 25 is defined on the outer peripheral side of the air motor 23. Note that shaping air is supplied to the main air chamber 25 through an air passage 26.

Reference numeral 27 denotes a motor case 23 of the air motor 23.
A shows a hollow cylindrical rotary shaft inserted in the axial direction in A. The rotary shaft 27 has a proximal end fixed to the air turbine 23C and a distal end protruding outside the motor case 23A.
The rotating shaft 27 is driven to rotate at a high speed by the air turbine 23C.

Numeral 28 is located outside the air motor 23 and fixed to the tip end of the rotating shaft 27, and is made of an insulating resin material (for example, polyether sulfone (PES), polyphenylene sulfide (PPS), polyetherimide (PEI), A bell-shaped rotary atomizing head formed of ether ether ketone (PEEK) or the like;
As shown in FIG. 2, is formed in a morning glory shape in which the base end side is attached to the rotating shaft 27 and the front end side is gradually expanded. The front side of the rotary atomizing head 28 is a paint smooth surface 28A, and the outer peripheral end of the paint smooth surface 28A is the paint smooth surface 2A.
Paint release edge 28 for spraying paint diffused by 8A
B.

Numeral 29 denotes a hub member which is screwed to the center of the front side of the rotary atomizing head 28 and is formed of an insulating resin material together with the rotary atomizing head 28. As shown in FIG. 3, the first hub holes 29A, 29 for guiding a cleaning solvent such as paint or thinner discharged from a feed tube 37 to be described later to the paint discharge edge 28B side.
Are provided in the center, and second hub holes 29B, 29B,... For supplying a cleaning solvent are provided in the center portion on the front side.

[0029] 30 shows the market shares over pings air ring provided on the cylindrical portion 22B tip end of the housing 22, the shaping air ring 30, outer ring 31, inner ring 32 to be described later, the sub air chamber 33, air ejection holes 34.

Reference numeral 31 denotes an outer ring formed of an insulating resin material into a cylindrical shape. The outer ring 31 has a male threaded portion 31A whose outer periphery on the base end is screwed to a female threaded portion 22D of the housing 22, and a distal end thereof. The outer nozzle portion 31B extends so as to gradually reduce the diameter of the side.

Reference numeral 32 denotes an inner ring which is screwed into the outer ring 31 and is formed in a stepped cylindrical shape from an insulating resin material. The inner ring 32 defines a sub air chamber 33 between itself and the outer ring 31. Has formed. On the base end side of the inner ring 32, communication holes 32A, 32A for communicating the main air chamber 25 and the sub air chamber 33 are formed, and the front end side extends to the vicinity of the front end of the outer nozzle portion 31B of the outer ring 31. The inner nozzle portion 32B extends.

Reference numeral 34 denotes an annular air ejection hole formed between the outer nozzle portion 31B and the inner nozzle portion 32B. The air ejection hole 34 extends from the air passage 26 to the main air chamber 25 and the sub air chamber. Air supplied through the nozzle 33 is ejected as shaping air toward the outer peripheral side of the rotary atomizing head 28, and the paint discharging edge 2 of the rotary atomizing head 28.
The spray pattern of the paint sprayed from 8B is formed into a circular pattern.

Reference numerals 35, 35,... Indicate a plurality of corona pins made of an elastic metal wire such as a piano wire, for example, as shown in FIG. For example, six are arranged at equal intervals in the circumferential direction. The corona pins 35 are electrically connected to the motor case 23A of the air motor 23 via the high-resistance element 36 while being held by the inner ring 32 together with a high-resistance element 36 described later. It protrudes from the ejection hole 34 toward the vicinity of the paint discharge edge 28B of the rotary atomizing head 28. And
Each of the corona pins 35 is supplied with power from -60 to -120 [k
V] is discharged from the tip side 35A to charge the paint sprayed from the paint discharge edge 28B of the rotary atomizing head 28.

Reference numerals 36, 36 denote high resistance elements (only two are shown) located in the sub air chamber 33 and connected to the corona pins 35, respectively. The high resistance elements 36 are connected to the air motor 23 via a touch plate 36A. And is electrically connected to the motor case 23A. The resistance value of each of the high-resistance elements 36 is such that the high-voltage generator 8, the high-voltage cable 10,
A value suitable for preventing the electric charge stored as a floating capacitance in the air motor 23 or the like from being discharged at once, for example, 10 ⁷ to 1
Those having a range of ⁰⁹ Ω are used. Here, the high voltage is 6
When the voltage is 0 kV or less, it is preferably set to be 10 ⁷ to 10 ⁸ Ω, and when the voltage is 60 kV or more, it is preferably set to be 10 ⁸ to 10 ⁹ Ω.

On the other hand, reference numeral 37 denotes a feed tube which is provided coaxially in the rotary shaft 27 and discharges paint or the like toward the hub member 29, and 38 denotes a paint passage for supplying paint to the feed tube 37. The passage 38 is connected to the color changing valve device 7 via the paint pipe 6. The paint passage 38 is opened and closed via a paint valve (not shown).

Reference numeral 39 denotes a motor case 23 of the air motor 23.
A is a connection terminal for supplying a high voltage to A.
9 is connected to a high voltage generator 8 via a high voltage cable 10. Therefore, since each corona pin 35 is in contact with and electrically connected to the motor case 23A of the air motor 23, a high voltage from the high voltage cable 10 is supplied to each corona pin 35 via the motor case 23A.

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 the present embodiment, in the coating operation, the paint valve is opened while the rotary atomizing head 28 is rotated at a high speed by the air motor 23 in substantially the same manner as the conventional electrostatic coating apparatus. By opening the valve, the paint in the paint tank is supplied to the rotary atomizing head 28 via the paint passage 38 and the feed tube 37, and is sprayed from the rotary atomizing head 28, and the high voltage from the high voltage generator 8 is supplied. The sprayed paint is charged to apply the atomized paint particles to an object to be coated by using the force of an electrostatic field.

In this embodiment, however, the high voltage supplied from the high voltage generator 8 to the motor case 23A of the air motor 23 via the high voltage cable 10 and the connection terminal 39 is applied to each of the corona pins 35 from the motor case 23A. To the paint discharge edge 28 of the rotary atomizing head 28.
A corona discharge region is formed on the B side.

Accordingly, by opening the paint valve while the rotary atomizing head 28 is rotating at a high speed, the paint passage 3 is opened.
8. The paint supplied through the feed tube 37
While being diffused on the paint smooth surface 28A by the rotation of the rotary atomizing head 28, the paint is sprayed radially outward at the paint discharge edge 28B. At this time, since the corona discharge region is formed around the paint discharge edge 28B, the paint particles sprayed from the paint discharge edge 28B can be charged. Further, the sprayed charged paint particles fly while applying the force of the electrostatic field formed between the paint spray pattern and the object to be coated while the paint spray pattern is formed by the shaping air ejected from the shaping air ring 30. It is designed to be applied to an object to be coated.

Thus, according to the present embodiment, unlike the conventional rotary atomizing head 5, the rotary atomizing head 28 and the shaping air ring 30 are formed of an insulating resin material which is an electrical insulator. Therefore, even if the rotary atomizing head 28 or the shaping air ring 30 abnormally approaches the workpiece, it is possible to prevent the discharge from being generated between the rotary atomizing head 28 or the shaping air ring 30 and the workpiece. Thus, a fire accident due to spark discharge can be prevented, and the safety and reliability of the electrostatic coating machine 21 can be improved.

In this embodiment, each high-resistance element 36 is provided so as to be connected to each corona pin 35.
Therefore, even if each corona pin 35 is short-circuited with the object to be coated, each high-resistance element 3
The electric charge stored in the high-voltage generator 8, the high-voltage cable 10, the air motor 23, etc., which is located on the power supply side of the electric motor 6, is prevented from being discharged. Also, only very small electric charges can be discharged, and a fire accident due to spark discharge can be prevented, and sufficient safety can be ensured. Further, since each high-resistance element 36 is housed in the shaping air ring 30, it is possible to prevent each high-resistance element 36 from being damaged by paint or a solvent, and to greatly improve the life and reliability. .

Further, in this embodiment, each corona pin 35 is provided on a shaping air ring 30 for blowing shaping air toward the paint sprayed from the rotary atomizing head 28 in order to form a spray pattern of the paint. since has a configuration to accommodate the respective high-resistance element 36 in the chamber 33, the shaping air ring 30 from Current come to effective use, the retainer of the corona pin 35 in addition to shaping air outlet functions, the high resistance element 36 It can be used as a protective cover, and external electrodes can be provided without significant design changes.

The motor case 23 of the air motor 23
A is electrically connected to the high voltage generator 8 via the connection terminal 39 and the high voltage cable 10, and the corona pin 35 is screwed to the housing 22 to connect the corona pin 35 to the touch plate of each high resistance element 36. Since the motor case 23A is electrically connected to the motor case 23A via 36A, each corona pin 35, a lead wire for connecting the high-resistance element 36 to the high-voltage cable 10, and the like can be eliminated. As a result, each corona pin 35 and high-resistance element 36
Can be easily attached to the inner ring 32. In particular,
When a plurality of corona pins 35 are provided as in the present embodiment, assembling workability can be greatly improved, and
Even when the number of corona pins 35 is increased, it can be easily handled.

[0045]

[0046] In the embodiment, is provided by connecting the respective high-resistance element 36 to each corona pin 35, for example, FIG.
As in the first modification shown in 4, one of a plurality of the high-resistance element 41 corona pin 42, 42, ... may be provided by branching a.

In the embodiment, each corona pin 35 and the high resistance element 36 are connected to the motor case 23A of the air motor 23, and are connected to the high voltage cable 10 via the motor case 23A. The second shown in 5
As in the modified example, the corona pin 51 and the high-resistance element 52 may be connected to the high-voltage cable 10 via the lead wire 53 .

Further, each corona pin 35 (42 , 51 )
The high resistance element 36 (41 , 52 ) does not need to be formed as a separate member. Of the lead wires provided at both ends of the high resistance element 36 (41 , 52 ), the lead wire on the free end side is used as a corona pin. May be used.

The corona pin 35 (42 , 51 ) and the high-resistance element 36 (41 , 52 ) may be connected as separate members via a short wire.

Further, in the embodiment, the case where six corona pins 35 are provided is exemplified. However, one to five or less or seven or more corona pins 35 may be provided.

Further, each corona pin 35 may be arranged in a radially double or triple manner. For example, 12 corona pins 35 are used, and two corona pins 35 are provided at six locations in the circumferential direction. In this case, the rotary atomizing head 2
8, the paint sprayed can be charged efficiently.

On the other hand, in the embodiment, the case where the high-voltage generator 8 is provided outside the electrostatic coating machine 21 is exemplified. However, instead, the high-voltage generator is built in the electrostatic coating machine. You may.

[0053]

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, and extends toward the vicinity of the paint discharge edge of the rotary atomizing head. A shaping air ring made of an insulating resin material is provided, and a tip side of the shaping air ring extends toward a vicinity of a paint discharge edge of the rotary atomizing head, and a high voltage is applied.
Providing a corona pin connected to the generator ;
And a high-voltage generating device . Therefore, even if the rotary atomizing head or shaping air ring , which is an electrical insulator, abnormally approaches the object to be coated, it is possible to prevent discharge and enhance safety,
On the other hand, by using the high-resistance element, even if the corona pin abnormally approaches the object to be coated, the electric charge stored on the power supply side existing between the high-voltage generator and the high-voltage cable passes through the corona pin. Discharge of the object to be coated can be prevented, sufficient safety can be ensured only by discharging extremely minute electric charges on the corona pin at the tip end side of the high-resistance element, and sufficient reliability can be improved. In addition, shaping air
The shaping aerin
To the function of blowing shaping air
It can be used as a holder for corona pins.

Further, according to the invention of claim 2, protrudes co Ronapi <br/> down from the tip of market shares over ping air ring,
High air resistance element air shaping sub air channel
Since it is housed in a bag , the existing shaping air ring can be effectively used, added to the shaping air ejection function, and used as a corona pin holder and a protective cover for high-resistance elements, without any design change. Electrodes can be provided.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view showing an electrostatic coating machine according to a first embodiment of the present invention.

FIG. 2 is an enlarged longitudinal sectional view of a main part showing a rotary atomizing head, a shaping air ring, a rotating shaft and the like in FIG.

FIG. 3 is a front view showing a rotary atomizing head, a hub member, a corona pin, and the like from the direction of arrows III-III in FIG.

FIG. 4 is a circuit diagram showing each corona pin and a high-resistance element according to a first modified example.

FIG. 5 is a longitudinal sectional view showing an electrostatic coating machine according to a second modification.

FIG. 6 is a system diagram of a conventional electrostatic coating apparatus.

FIG. 7 is an explanatory diagram showing a relationship between a rotary atomization head and a stray capacitance according to a conventional technique.

[Explanation of symbols]

8 high-voltage generator 2 1 electrostatic coating machine 2 3 air motor 23A motor case 2 7 rotary shaft 2 8 rotary atomizing head 28B paint releasing edges 30 shaping air-rings 35, 42, 51 corona pin 35A distal end 36, 41, 52 High resistance element

Claims (2)

(57) [Claims] 1. A rotary shaft rotated by an air motor, a rotary atomizing head provided on a tip side of the rotary shaft and formed of an insulating resin material and having a paint discharge edge on an outer peripheral side; Formed by the material and extending near the paint discharge edge of the rotary atomizing head , the paint spray pattern
That blows out shaping air for molding
A ring air ring, provided in the shaping air ring, the tip end side is extended toward the vicinity of the paint releasing edges of the rotary atomizing head, a corona pin connected to a high voltage generator, the corona pin to the high voltage A rotary atomizing head type coating apparatus comprising a high resistance element connected between the generator and the generator. 2. A shaping air ring has a sub air
A corona pin is provided so as to protrude from a tip of the shaping air ring , and the high-resistance element is provided.
Rotary atomizing head type coating apparatus according to claim 1 comprising a configuration to be accommodated in the sub air chamber.