JPH04260461A - Electrostatic painting method and apparatus - Google Patents

Abstract

PURPOSE:To efficiently and easily perform painting work as a whole by rapidly forming a voltage block between a paint supply source and an intermediate storage tank and efficiently utilizing conductive paint and a cleaning solution. CONSTITUTION:After conductive paint is supplied to an intermediate storage tank 18 from a color changing valve mechanism 14 through a first route 16, the color changing valve mechanism 14 and the first route 16 are cut off through a two-way valve 24 and effective electric insulation is formed by the two-way valve 24 itself. Therefore, immediately after the two-way valve 2 is changed over, the conductive paint is supplied to a painting gun 22 from the intermediate storage tank 18 through a second route 20 and painting work can be performed easily and efficiently as a whole.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrostatic coating method and apparatus for electrostatic coating using a conductive paint to which a high voltage is directly applied.

0002

[Prior Art] As a method of applying electrostatic coating to an object to be coated such as an automobile body by directly applying a high voltage to a conductive paint, a technique disclosed, for example, in Japanese Patent Application Laid-Open No. 2-2885 is known. . This is done by the fact that once the conductive paint has been introduced into the reservoir, the insulating paths communicating this reservoir with the paint supply are cleaned and dried to form the voltage block. Conductive paint to which a high voltage is directly applied is supplied from the intermediate storage tank to the paint gun while preventing electrical leakage to the paint supply source to perform electrostatic painting on the object to be painted.

0003

[Problems to be Solved by the Invention] However, with the above technique, after filling the reservoir with conductive paint, cleaning and drying of the insulation path must be performed to form a voltage block, which makes the entire painting process difficult. The cycle time becomes considerably long. Furthermore, regardless of whether the conductive paint used for the next painting is of the same color or a different color, cleaning and drying work is required to form a voltage block, and the conductive paint remaining in the path is left unused and exposed to the outside. This results in an increase in the amount of wasted conductive paint and cleaning fluid, and a problem that the cleaning time becomes longer.

The present invention solves this type of problem by allowing a voltage block to be quickly formed between the paint supply source and the intermediate reservoir, while also efficiently discharging the conductive paint and cleaning fluid. It is an object of the present invention to provide an electrostatic coating method and apparatus that can be utilized to easily improve the efficiency of the entire coating work.

[0005]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention provides an electrically isolable switching valve in a conductive paint path from a grounded conductive paint supply source. supplying conductive paint to the intermediate storage tank via the
a step of electrically insulating the conductive paint supply source and the intermediate storage tank by switching the switching valve to cut off the conductive paint path; and applying paint from the intermediate storage tank in the electrically insulated state. The present invention is characterized by comprising a step of supplying conductive paint to a gun and performing a painting operation.

Furthermore, the present invention provides a grounded paint valve mechanism including at least one paint valve, an intermediate reservoir connected to the paint valve mechanism via a first path, and a first reservoir connected to the intermediate reservoir. A coating gun that is connected via two paths and sprays conductive paint onto the object to be coated can selectively switch communication and disconnection between the paint valve mechanism and the first path, and can be electrically isolated when disconnected. It is characterized by comprising a switching valve.

[0007]

[Operation] In the electrostatic coating method according to the present invention, the conductive paint is supplied from the grounded conductive paint supply source to the intermediate storage tank via the switching valve, and then the switching valve is switched. Simply blocking the conductive paint path electrically isolates the conductive paint supply source from the intermediate reservoir. For this reason,
The conductive paint to which a high voltage has been applied can be quickly supplied from the intermediate storage tank to the paint gun, making it possible to perform painting work efficiently.

Furthermore, in the electrostatic coating apparatus according to the present invention, after the conductive paint is supplied from the paint valve mechanism to the intermediate storage tank via the first path, the conductive paint is connected to the paint valve mechanism and the second tank through the switching valve. The paint valve mechanism and the intermediate storage tank are electrically insulated by only one path being cut off, and in this state, conductive paint is supplied from the intermediate storage tank to the coating gun via the second path to perform painting. Work is done. Therefore, voltage blocks can be formed quickly, and cleaning operations and the like can be performed easily and efficiently.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The electrostatic coating method and apparatus according to the present invention will be described in detail below by giving examples and referring to the accompanying drawings.

In FIG. 1, reference numeral 10 indicates an electrostatic coating apparatus according to a first embodiment of the present invention. This electrostatic coating device 10 includes a grounded color change valve mechanism (paint valve mechanism) 14 including a plurality of paint valves 12a to 12c capable of supplying different conductive paints, and a color change valve mechanism 14 that is connected to the color change valve mechanism 14. an intermediate storage tank 18 connected via a first path 16; a coating gun 22 connected to the intermediate storage tank 18 via a second path 20 and spraying a conductive paint onto an object (not shown); A two-way valve (switching valve) 24 is provided that selectively switches communication and isolation between the color change valve mechanism 14 and the first path 16 and can be electrically insulated when the communication is interrupted.

The color change valve mechanism 14 has air (A) and water (W).
) and a cleaning valve 25 for controlling the supply of cleaning liquid (S) and the like. As shown in FIG. 2, the two-way valve 24 connected to the outlet side of the color change valve mechanism 14 rotates relative to a passage body 30 having two passages 26 and 28. and a valve body 32 that can be engaged with each other. The passage body 30 is formed of an insulating material such as ultra-high molecular weight polyethylene, and one opening of the passages 26 and 28 is arranged on one plane 34 side of the passage body 30. Valve body 3
2 is similarly made of an insulating material such as ultra-high molecular weight polyethylene, and includes an arcuate passage 36 that can freely communicate with and block the passages 26 and 28 (see FIG. 3).

A rotary drive source 40 is fixed to the passage body 30 via a casing 38, and a first coupling member 44 is fixed to a rotating shaft 42 extending from the rotary drive source 40. The second meshing with
A rod 48 is inserted into coupling member 46 . This rod 48 extends externally through the passage body 30, and a spring 50 is arranged at the end of this rod 48, via which the rod 48 is connected to the second coupling member 4.
6 to press the valve body 32 against the plane 34 of the passage body 30.

The casing 38, the first and second coupling members 44, 46, and the rod 48 are made of a conductive material such as stainless steel, and are located at the portion where the flat surface 34 of the passage body 30 and the valve body 32 are in close contact with each other. The shortest distance L1 between the passages 26, 28 and the rod 48 which is a conductor, the arcuate passage 3
6 and the second coupling member 46 which is a conductor, and the shortest distance L3 between this passage 26 and the passage 28.
is selected to be greater than or equal to the distance (mm) obtained by dividing the voltage (kV) directly applied to the conductive paint by the dielectric breakdown strength (kV/mm) of this type of insulating material.

The intermediate storage tank 18 includes a first cylinder chamber 54 for injecting conductive paint and cleaning liquid, which is divided by a piston 52, and a second cylinder chamber 56 for supplying air.
An air supply source 58 communicates with this second cylinder chamber 56 via a flow rate adjustment valve 60 and an on-off valve 62 . This air supply source 58 is connected via a booster 64 to a conductive paint flow rate regulator 66 for adjusting air pressure, and the flow rate regulator 66 controls the discharge amount of the conductive paint.

The first cylinder chamber 54 of this intermediate storage tank 18
A painting gun 22 is connected to via a second path 20,
The coating gun 22 includes a dump valve 68 and a trigger valve 70, and is connected to high voltage application means (not shown).

Next, the operation of the electrostatic coating apparatus 10 constructed as described above will be explained. First, in the two-way valve 24, the valve body 32 is driven by the passage body 3 under the driving action of the rotational drive source 40.
The passage 2 of this passage body 30 is rotated by a predetermined angle with respect to 0.
6 and 28 communicate with each other through an arcuate passage 36 of the valve body 32 (see the two-dot chain line in FIG. 3). Then, conductive paint of a predetermined color is pumped from the paint valve 12a of the color change valve mechanism 14, and is passed through the passages 26, 28 of the two-way valve 24 and the first path 16 to the first cylinder chamber 54 of the intermediate storage tank 18. The coating gun 22 is further filled via the second path 20. During this filling, the trigger valve 70 is closed, while the dump valve 68 is opened, and after filling, the dump valve 68 is closed.

Therefore, the valve body 32 is rotated by a predetermined angle (substantially 90°) with respect to the passage body 30 under the driving action of the rotational drive source 40 constituting the two-way valve 24.
0 passages 26 and 28 are blocked (see solid line in FIG. 3).
. Next, the second cylinder chamber 56 of the intermediate storage tank 18 is supplied from the air supply source 58 via the flow rate adjustment valve 60 and the on-off valve 62.
Driving air is supplied to the piston 52, the piston 52 is displaced toward the first cylinder chamber 54, and the conductive paint is sprayed onto a workpiece (not shown) under the opening action of the trigger valve 70 while a high voltage is applied. .

In this case, in this embodiment, the passages 26 and 28 at the portion where the flat surface 34 of the passage body 30 and the valve body 32 are in close contact with each other.
and the shortest distance L1 between the rod 48 and the arcuate passage 36 and the second
The shortest distance L2 to the coupling member 46 and the shortest distance L3 between the passage 26 and the passage 28 determine the voltage (kV) directly applied to the conductive paint, which is the dielectric breakdown strength (kV) of this type of insulating material. (kV/mm) divided by the distance (mm) or more. Therefore, simply by blocking the passages 26 and 28 of the passage body 30 under the rotational action of the valve body 32, it is possible to effectively prevent current leakage from occurring in the two-way valve 24 when applying a high voltage to the conductive paint. can do.

That is, by blocking the passage 26 and the passage 28, the color change valve mechanism 14 and the intermediate storage tank 18 are electrically insulated, so that the conventional work of cleaning and drying the insulation path can be omitted. This makes it possible to achieve the effect of shortening the cycle time of the entire painting operation at once. Furthermore, there is an advantage that cleaning and drying operations are not required when forming the voltage block, and the amount of cleaning liquid used is significantly reduced, making it economical.

Next, an electrostatic coating apparatus 80 according to a second embodiment of the present invention will be described with reference to FIGS. 4 and 5. Note that the same reference numerals as in the electrostatic coating apparatus 10 according to the first embodiment indicate the same components, and detailed explanation thereof will be omitted.

This electrostatic coating device 80 has a color changing valve mechanism 14.
A discharge path 82 for discharging conductive paint, water, and cleaning liquid is provided between the intermediate storage tank 18 and the color change valve mechanism 14.
A three-way valve (switching valve) 84 is provided which selectively communicates with the path 16 and the exhaust path 82 and which is electrically insulated when connected to the exhaust path 82.

As shown in FIG. 5, this three-way valve 84 includes a passage body 94 made of an insulating material in which one opening of three passages 86 to 90 is arranged on the same virtual circumference with a plane 92; A valve body 98 made of an insulating material is provided, which is rotatably engaged with the body 94 and is formed with an arcuate passage 96 that can freely communicate any two of the passages 86 to 90. Similar to the two-way valve 24 described above, the shortest distance between the passages 86 to 90 and the rod 48 at the part where the flat surface 92 of the passage body 94 and the valve body 98 are in close contact with each other, and the distance between the arcuate passage 96 and the second coupling member 46 are The shortest distance and the shortest distance between the paths 86 to 90 are determined by the voltage (k) directly applied to the conductive paint.
V) is the dielectric breakdown strength of this type of insulating material (kV/m
The selected distance is greater than or equal to the distance (mm) divided by m).

Therefore, the passage 86 is connected to the color change valve mechanism 14, the passage 88 is connected to the intermediate storage tank 18, and the passage 90 is connected to the discharge passage 82. , 88 are in communication, the color change valve mechanism 1
4 is driven. Then, the conductive paint of the desired color passes from the first path 16 to the intermediate storage tank 18 to the paint gun 22.
After being filled, the valve body 98 is rotated to block the passage 86 and the passage 88, and the passage 86 communicates with the discharge passage 82 via the passage 90.

Therefore, similar to the two-way valve 24, the three-way valve 84
By simply blocking the passage 86 and the passage 88 by the switching operation, the color change valve mechanism 14 and the intermediate storage tank 18 can be electrically insulated, and the efficiency of the painting work can be easily achieved.

Moreover, in this electrostatic coating device 80, when painting is performed via the coating gun 22, the cleaning valve 25 constituting the color changing valve mechanism 14 is driven, and the color changing valve mechanism 14 is The cleaning operation is performed up to the passage 90 of the three-way valve 84. Therefore, when conductive paints of different colors are used, the three-way valve 84 is driven to connect the passages 86 and 88, and then the three-way valve 84 is connected to the paint gun 22 via the cleaning valve 25. It is only necessary to carry out the cleaning work, and the effect is that the cleaning time can be effectively shortened.

Next, an electrostatic coating apparatus 100 according to a third embodiment of the present invention will be described with reference to FIGS. 6 and 7. Note that the same reference numerals as in the electrostatic coating device 80 according to the second embodiment indicate the same components, and detailed explanation thereof will be omitted.

This electrostatic coating apparatus 100 includes a cleaning valve mechanism 106 that includes an air valve 102 that controls the supply of air (A), and a cleaning valve 104 that controls the supply of water (W) and cleaning liquid (S). , an insulating path 108 provided between the cleaning valve mechanism 106 and the first path 16 and having a length capable of insulating at least the voltage applied to the conductive paint with air.
, the color change valve mechanism 14 and the cleaning valve mechanism 106 are connected to the first path 1.
6 and a four-way valve (switching valve) 110 that selectively communicates with the discharge path 82.

This four-way valve 110, as shown in FIG.
One opening of the four passages 112 to 118 is a flat surface 120.
Passage bodies 12 made of insulating material arranged on the same virtual circumference in
2, and a valve body 128 made of an insulating material, which is rotatably engaged with the passage body 122 and is formed with arcuate passages 124 and 126 that can freely communicate any two pairs of passages 112 to 118. Equipped with. The passage 112 is the color change valve mechanism 1
4, the passage 114 is connected to the cleaning valve mechanism 106, the passage 116 is connected to the intermediate storage tank 18, and the passage 118 is connected to the discharge passage 82, and the passage 114 is connected from the outlet of the cleaning valve mechanism 106.
The path leading to the passage 116 via the insulating path 108 constitutes an insulating path 108.

Electrostatic coating apparatus 100 configured as described above
In this case, conductive paint of a predetermined color is pumped from the paint valve 12a of the color change valve mechanism 14 into the passages 112, 1 of the four-way valve 110.
16 and the first of the intermediate reservoir 18 via the first path 16
The cylinder chamber 54 is filled, and the paint gun 22 is further filled via the second path 20. During this time, the insulation path 108 and the passage 1 are connected via the cleaning valve 104 of the cleaning valve mechanism 106.
14 and passage 118 are cleaned and dried.

Next, the four-way valve 110 is driven to open the passage 1.
12 and the passage 118, and the passage 114 and the passage 116 communicate with each other, whereby the passage 112 and the passage 116 are cut off. At this time, since the insulating path 108 from the cleaning valve mechanism 106 to the passage 116 has been cleaned and dried, a voltage block is formed in this insulating path 108. Therefore,
Immediately after switching this four-way valve 110, the intermediate storage tank 18
The effect is that the painting work can be carried out using the conductive paint inside. Here, for example, in conductive paint -
Assuming that a high voltage of 60 kV is applied, the insulation path 10
By selecting the length of the insulating path 8 to be 200 mm or more, an electrically insulating state can be effectively obtained in this insulating path 108.

Therefore, if the next color is the same color, the four-way valve 1
After the four-way valve 110 is switched as described above and the painting operation is performed, the four-way valve 110 is switched again to the state shown in FIG. Next, the intermediate storage tank 18 is filled with conductive paint from the paint valve 12a of the color change valve mechanism 14, and the four-way valve 110 is filled with conductive paint.
At the same time, conductive paint to which a high voltage is applied is sprayed from the paint gun 22. During this time, cleaning and drying work from the cleaning valve mechanism 106 to the passage 118 may be performed as necessary.

By the way, if the next color is a different color, the passages 112 and 118 are cleaned from the color change valve mechanism 14 via the cleaning valve 25 of the color change valve mechanism 14 during the electrostatic painting operation. . After the painting operation is finished, while continuing the cleaning operation using the cleaning valve 25, the cleaning valve mechanism 106 connects the insulation path 108 to the first path 16, intermediate storage tank 18,
Cleaning of the second path 20 and the coating gun 22 is started. Furthermore, after the cleaning from the color change valve mechanism 14 to the passage 118 is completed, the four-way valve 110 is switched and the cleaning valve 2
5, the intermediate storage tank 18 and the coating gun 22 are cleaned, while the insulation path 108 is dried by the air valve 102 of the cleaning valve mechanism 106. Thereafter, the intermediate storage tank 18 is filled with conductive paint of a desired color from the color change valve mechanism 14, and the next color painting operation is performed using this conductive paint in the same manner as in the process described above.

Furthermore, in this electrostatic coating apparatus 100, an insulating path 10 leading from the cleaning valve mechanism 106 to the four-way valve 110 is provided.
8 is provided, and this insulating path 108 is cleaned and dried to form electrical insulation, but similarly to the electrostatic coating devices 10 and 80 according to the first and second embodiments, this four-way valve 110
It is also possible to form the electrical insulation by itself. That is, the shortest distance between the rod 48 and the passages 112 to 118 at the part where the flat surface 120 of the passage body 122 and the valve body 128 are in close contact with each other, the shortest distance between the arcuate passages 124 and 126 and the second coupling member 46, and this passage. 112 to 118
The shortest distance between them is the voltage applied directly to the conductive paint (
kV) and the dielectric breakdown strength (kV/
It suffices if the selected distance is greater than or equal to the distance (mm) divided by (mm).

[0034]

[Effects of the Invention] According to the electrostatic coating method and apparatus according to the present invention, the following effects can be obtained.

[0035] After the conductive paint is supplied from the grounded conductive paint supply source to the intermediate storage tank via the switching valve, simply by switching the switching valve to cut off the path for the conductive paint. The conductive paint source and the intermediate reservoir are electrically isolated. Therefore, there is no need to clean or dry the path to form a voltage block after switching the switching valve, and conductive paint can be quickly supplied from the intermediate storage tank to the painting gun, reducing the entire painting process. This allows for efficient execution.

[Brief explanation of the drawing]

FIG. 1 is a schematic configuration diagram of an electrostatic coating apparatus according to a first embodiment of the present invention.

FIG. 2 is a longitudinal sectional view of a two-way valve constituting the electrostatic coating apparatus according to the first embodiment.

FIG. 3 is an explanatory plan view of the two-way valve.

FIG. 4 is a schematic configuration diagram of an electrostatic coating apparatus according to a second embodiment of the present invention.

FIG. 5 is an exploded perspective view of a three-way valve constituting the electrostatic coating apparatus according to the second embodiment.

FIG. 6 is a schematic configuration diagram of an electrostatic coating apparatus according to a third embodiment of the present invention.

FIG. 7 is an exploded perspective view of a four-way valve constituting the electrostatic coating apparatus according to the third embodiment.

[Explanation of symbols]

10...Electrostatic coating device 12a-12c...Paint valve 14...Color change valve mechanism 16...route 18...Intermediate storage tank 20...route 22...painting gun 24...Two-way valve 30...Passage body 32... Valve body 80...Electrostatic coating device 82...Emission route 84...Three-way valve 94...Passage body 98... Valve body 100...Electrostatic coating device 102...Air valve 104...Washing valve 106...Washing valve mechanism 108...Insulation path 110...Four-way valve 122...Passage body 128... Valve body

Claims (8)

[Claims] 1. A process for supplying conductive paint from a grounded conductive paint supply source to an intermediate storage tank via an electrically insulating switching valve provided in a conductive paint path; electrically insulating the conductive paint supply source from the intermediate reservoir by switching a switching valve to cut off the conductive paint path; and in the electrically insulated state, removing the paint gun from the intermediate reservoir 1. An electrostatic coating method comprising the steps of supplying conductive paint to a container and performing a coating operation. 2. A grounded paint valve mechanism comprising at least one paint valve; an intermediate reservoir connected to the paint valve mechanism via a first path; and an intermediate reservoir connected to the intermediate reservoir via a second path. A paint gun that is connected to and sprays conductive paint onto an object to be painted, and a switching valve that selectively switches communication and disconnection between the paint valve mechanism and the first path and can be electrically insulated at the time of disconnection. An electrostatic coating device comprising: 3. The electrostatic coating apparatus according to claim 2, wherein the switching valve has one opening of the two passages communicating with a passage body made of an insulating material provided on one plane side. A passage is formed, and a valve body made of an insulating material is rotatably engaged with the flat surface relative to the passage body, and the passage and the conductor are connected at a portion where the flat surface and the valve body are in close contact with each other. The shortest distance, the shortest distance between the passage of the valve body and the conductor, and the shortest distance between each passage are selected to be greater than or equal to the distance obtained by dividing the voltage directly applied to the conductive paint by the dielectric breakdown strength of the insulating material. An electrostatic coating device characterized by: 4. The electrostatic coating apparatus according to claim 2, further comprising a discharge path disposed between the paint valve mechanism and the intermediate storage tank for discharging the conductive paint and/or the cleaning fluid, the paint valve The mechanism is configured to be able to freely switch between a cleaning valve for supplying cleaning fluid and a plurality of paint valves, and the switching valve is
An electrostatic coating apparatus characterized in that the paint valve mechanism is a three-way valve that selectively communicates with a first path and a discharge path and is electrically insulated when communicated with the discharge path. 5. The electrostatic coating device according to claim 4, wherein the three-way valve is formed of an insulating material in which one opening of the three passages is arranged on the same virtual circumference and provided on one plane side. a valve body made of an insulating material, the passage body being formed with a passage that communicates with at least one pair of openings adjacent to each other on the circumference, and engaging the plane so as to be rotatable relative to the passage body; The shortest distance between the passage and the conductor at the part where the flat surface and the valve body are in close contact with each other, the shortest distance between the passage of the valve body and the conductor, and the shortest distance between each passage are directly connected to the conductive paint. An electrostatic coating device characterized in that the distance is selected to be greater than or equal to the applied voltage divided by the dielectric breakdown strength of the insulating material. 6. The electrostatic coating apparatus according to claim 2, wherein a cleaning valve mechanism comprising an air valve for supplying air and a cleaning valve for supplying cleaning fluid, and a paint valve mechanism and an intermediate storage tank. and a discharge path for discharging conductive paint and/or cleaning fluid, the paint valve mechanism being configured to be able to freely switch between a cleaning valve for supplying cleaning fluid and a plurality of paint valves; The switching valve is a four-way valve having a passage that selectively communicates the paint valve mechanism and the cleaning valve mechanism with the first passage and the discharge passage, and in which the passages are electrically insulated from each other. Electrostatic painting equipment. 7. The electrostatic coating apparatus according to claim 2, wherein: a cleaning valve mechanism comprising an air valve for supplying air and a cleaning valve for supplying cleaning fluid; and a gap between the cleaning valve mechanism and the first path. An insulating path is provided between the paint valve mechanism and the intermediate storage tank, and has a length that can insulate at least the voltage applied to the conductive paint with air, and is arranged between the paint valve mechanism and the intermediate storage tank, and is arranged between the paint valve mechanism and the intermediate storage tank, The paint valve mechanism is configured to be able to freely switch between a cleaning valve for supplying cleaning fluid and a plurality of paint valves, and the switching valve is configured to switch between the paint valve mechanism and the cleaning valve mechanism. What is claimed is: 1. An electrostatic coating device characterized in that the electrostatic coating device has a passageway that selectively communicates the first passageway and the discharge passageway, and is a four-way valve in which the passageways are electrically insulated from each other. 8. The electrostatic coating device according to claim 6 or 7, wherein the four-way valve has one opening of the four passages arranged on the same virtual circumference and provided on one plane side. A passage body made of an insulating material and a passageway that communicates with at least one pair of openings adjacent to each other on the circumference are formed, and the passage body is made of an insulating material and engages with the plane so as to be rotatable relative to the passage body. a valve body, and the shortest distance between the passage and the conductor at the part where the flat surface and the valve body are in close contact with each other, the shortest distance between the passage of the valve body and the conductor, and the shortest distance between each passage are made of conductive paint. An electrostatic coating device characterized in that the distance is selected to be greater than or equal to the voltage directly applied to the insulating material divided by the dielectric breakdown strength of the insulating material.