JPH0351472B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an electrostatic coating method in which two or more colors of paint can be sequentially changed and sprayed using one sprayer.

Conventionally, large electrostatic coating equipment is equipped with a color change valve device, which has a thinner valve and an air valve on the most upstream side of the manifold, and colors A and B toward the downstream side. ,...The configuration is such that a paint valve of N color is provided,
Each of the paint valves is connected to a paint tank via a circulation pipe, a paint pump, etc., and an electrostatic sprayer is connected to the tip of the manifold via a paint pipe. Then, paint is constantly circulated between each paint valve and the paint tank, and after the previous color is painted, thinner and air are alternately supplied from the thinner valve and air valve to the manifold, paint pipe,
High-speed cleaning of the spray machine in a short time of about 30 seconds, for example,
After this cleaning is completed, the paint valve for the next color is opened to begin painting.

However, the large electrostatic coating equipment described above not only requires a large color change valve device, but also requires N paint tanks, paint pumps, and N circulation pipes, making it extremely expensive. It has the disadvantage of getting used to it. Therefore, there has been a problem in that it is not suitable for anything other than large-scale applications such as those in automobile factories where vehicle bodies transported on a conveyor are sequentially painted.

On the other hand, in the case of a simple electrostatic coating device, one end of a paint pipe is connected to a paint tank, an electrostatic sprayer is installed at the other end of the paint pipe, and a paint pump is installed in the middle of the paint pipe. It is becoming. In order to change colors and spray two or more colors of paint sequentially using such a simple electrostatic painting device, connect a thinner tank to one end of the pipe after painting the previous color, and use the paint pump to supply thinner. The paint is supplied from the paint pipe to the electrostatic sprayer to clean the paint pump, paint pipe, electrostatic sprayer, etc. After that, a paint tank for the next color is connected to one end of the paint pipe, and the next color is applied to the inside of the paint pipe. After purging the thinner, the next color was applied.

However, although the simple electrostatic coating equipment mentioned above is small and can be manufactured at low cost, it requires about 10 minutes for cleaning and is difficult to use when painting while changing colors frequently. had the disadvantage of poor workability.

The present invention focuses on the advantages of a simple electrostatic coating device in that the device is small and can be manufactured at low cost. Like large electrostatic coating equipment, it can perform high-speed cleaning in a short time of about 30 seconds, and even when dealing with conductive paints such as water-based paints and metallic paints, the next color can be sprayed from the electrostatic sprayer. At the same time, the present invention provides an electrostatic coating method that can clean the previous color remaining in a paint supply passage between a color change valve and a paint tank.

In order to achieve the above object, the present invention includes one sprayer that sprays paint while applying a high voltage, and a first sprayer that controls the paint and cleaning fluid to be supplied to the sprayer. a second color change valve, and a first one that connects between the sprayer and each color change valve, respectively;
a second paint pipe, first and second paint supply passages that respectively connect between the first and second color change valves and one paint tank of a plurality of paint tanks storing a plurality of colors; After the painting of the previous color paint is completed, cleaning fluid is supplied to one of the first and second color change valves used for supplying the previous color paint to change the color of the one. After cleaning the valve, one paint pipe, and the sprayer, the next color paint supplied from the other paint supply passage is passed from the sprayer to the object to be coated via the other color change valve and the other paint pipe. The previous color paint remaining in the one paint supply passage between the one paint tank and the one color change valve after cleaning of the one color change valve, one paint pipe and the sprayer is completed. and after the cleaning of the previous color paint is completed, the color paints are circulated one after another between the one paint supply passage and the one color change valve to prepare for spraying of the successive color paints. It is an electrostatic painting method.

With the above configuration, one color change valve, one paint pipe, and the previous color paint of the sprayer are washed at high speed, and when the sprayer is clean, the sprayer is removed from the other color change valve through the other paint pipe. The next color paint can be immediately supplied to the next color and the next color can be applied, which can shorten the cleaning time. Additionally, while the next color paint is being sprayed, the previous color paint remaining in the paint supply passage between one paint tank and the color change valve can be cleaned, improving work efficiency. be able to. Furthermore, even if the next color paint is being sprayed while applying high voltage, one paint pipe is clean after washing the previous color paint, so one color change valve or paint The supply passage, paint tank, etc. can be grounded and maintained at earth potential, and even when using conductive paint, color changing work can be performed safely.

The present invention will be described below along with embodiments shown in the drawings.

In Figures 1 and 2, 1 indicates a sprayer, and the sprayer 1 may be a rotary atomizer head sprayer using centrifugal atomization, an air atomizer type sprayer using air atomization, or the like. It will be done. The sprayer 1 is connected to a high voltage generator 3 via a high voltage cable 2,
Further, the sprayer 1 may be equipped with a reciprocator R as needed.
It is configured so that it can spray paint onto the object while reciprocating.

4 and 5 indicate first and second paint pipes, one end of each paint pipe 4 and 5 is connected to the sprayer 1,
The other ends of the first and second ends are respectively held in an insulated state.
It is connected to second color change valves 6 and 7. here,
The length of each paint pipe 4, 5 is relatively short, about 40 to 60 cm, and the material used is a water-repellent material that has high insulation properties and can easily repel paint, thinner, etc. For example, polytetrafluoroethylene, etc. are used.

The first color change valve 6 described above is composed of a manifold 8, an air valve 9 fixed to the manifold 8, a thinner valve 10, and a paint valve 11, and the air valve 9 is connected to an air source 12 to supply air. The thinner valve 10 is connected to a thinner source 13 to control the supply of thinner, and the paint valve 11 is connected to a first paint supply passage 14 made of a conductive material to control the supply of paint. It's getting old. A pump 16 driven by a motor 15 is inserted into the supply side 14A of the paint supply passage 14, and both the supply side 14A and return side 14B of the paint supply passage 14 are inserted into the first paint tank 17. The paint tank 17 is placed on an insulating stand 18.

On the other hand, the second color change valve 7 also includes a manifold 19, an air valve 20, a thinner valve 21, and a paint valve 22.
Air valve 20 is connected to air source 23 and thinner valve 2
1 is connected to a thinner source 24, and the paint valve 22 is connected to a second paint supply passage 25 made of a conductive material. A pump 27 driven by a motor 26 is inserted into the supply side 25A of the paint supply passage 25, and both the supply side 25A and the return side 25B of the paint supply passage 25 are inserted into a second paint tank 28. The paint tank 28 is mounted on the insulating stand 2.
It is placed on 9.

Further, among the first and second color change valves 6 and 7, for example, the first color change valve 6 is configured as shown in FIG. That is, the manifold 8 has a passage 8A formed therein, an air valve 9 and a thinner valve 10 are connected to the upstream side of the passage 8A, and a paint valve 11 is connected to the downstream side of the passage 8A. It is connected to the paint pipe 4. Here, the air valve 9 is formed in its casing with a valve chamber 9A communicating with the passage 8A of the manifold 8 and the air source 12, and a partition chamber 9C in which a partition wall 9B such as a piston or a diaphragm is provided inside. A valve body 9E is provided in the chamber 9A and is seated on and off the valve seat 9D, and the valve body 9E is connected to the partition wall 9B via the valve stem 9F.
A spring 9G that always urges the valve body 9E toward the valve seat 9D is stretched on one side, and a driving air supply port 9H is formed on the other side. The thinner valve 10 also has the same configuration as the air valve 9, including a valve chamber 10A, a partition wall 10B, a partition chamber 10C, a valve seat 10D, and a valve body 10.
E, valve stem 10F, spring 10G, drive air supply port 1
Consists of 0H. Further, the paint valve 11 has a valve chamber 11A in its casing that communicates with the passage 8A of the manifold 8, the supply side 14A and the return side 14B of the paint supply passage 14, and a partition wall provided with a partition wall 11B such as a piston and a diaphragm inside. A chamber 11C is formed, and valve seats 11D and 11E are formed in the valve chamber 11A.
A valve body 11F is provided which seats and leaves the valve body 11F.
F is connected to the partition wall 11B via the valve stem 11G,
A valve body 11F and a valve seat 11D are disposed on one side of the partition wall 11B.
A spring 11H that is always biased is provided on one side, and a drive air supply port 11J is formed on the other side.
In the figure, numerals 30 and 31 are thinner tanks that store cleaning thinner and are placed near the insulating stands 18 and 29.

The coating apparatus used in this embodiment is constructed as described above.Next, the coating process will be explained with reference to the operational diagram of FIG. 3.

First, the paint tank 17 is of color A, and includes the first paint supply passage 14, the first color change valve 6, and the paint pipe 4.
The paint tank 28 is filled with color A, and the paint tank 28 is filled with the previous color, and the second paint supply passage 2 is filled with the color A as shown in FIG.
Although the interior of the paint pipe 5 is filled with the previous color, it is assumed that the second paint pipe 5 has been cleaned and is clean.

Here, if the sprayer 1 is a rotary atomizing head type sprayer, to paint color A, rotate the sprayer 1 at high speed as shown in Fig. 3 A, B, and C, and operate the reciprocator R to apply the color A. The atomizer 1 is reciprocated and a high voltage from a high voltage generator 3 is applied to the rotating atomizing head.

Next, when air is supplied from the driving air supply port 11J of the paint valve 11, the partition wall 11B is displaced upward against the spring 11H, and the valve body 11F is seated on the valve seat 11E. As a result, A from the paint supply passage 14
Apply colored paint to valve chamber 11A and passage 8 of manifold 8.
A. Supply to the sprayer 1 via the paint pipe 4.
As a result, as shown in FIG. 3D, color A is sprayed from the sprayer 1 toward the object to be coated, and it flies along the lines of electric force between the sprayer 1 and the object to be coated by suction. As a result, the color A is painted.

During this time, the paint tank 28 of the previous color is removed from the insulating stand 29, the thinner tank 31 is mounted, and the pump 27 is driven to supply thinner from the supply side 25A of the paint supply passage 25 to the pump 27 and the paint of the color change valve 7. valve 2
2. Return to the return side 25B and paint supply passage 2
5. Clean the previous color remaining in the pump 27 and paint valve 22. As a result, the previous color in the second paint supply passage 25 is cleaned as shown in FIG. 3H. After this cleaning is completed, remove the thinner tank 31 from the insulating stand 29, place the B color paint tank 28, and operate the pump 27 again to circulate B color between the second paint supply passage 25 and the paint valve 22. Then prepare for the next color painting.

On the other hand, when the sprayer 1 finishes spraying the paint of color A as shown in FIG.
In this state, the color change valve 6 is operated as shown in FIG. That is, when air is supplied from the driving air supply port 9H of the air valve 9, the partition wall 9B is displaced upward against the spring 9G, and the valve body 9E is moved against the valve seat 9D.
Leave the seat. As a result, cleaning air from the air source 12 is supplied to the sprayer 1 via the passage 8A of the manifold 8 and the paint pipe 4, and the air inside these
Purge color. Next, after closing the air valve 9,
Similarly to the above, the driving air supply port 10 of the thinner valve 10
Air is supplied from H to open the valve body 10E, and thinner from the thinner source 13 is supplied from the manifold 8 to the paint pipe 4 and the sprayer 1 to clean the inside thereof. By repeating the supply of cleaning air and thinner multiple times as described above, the manifold 8,
Thoroughly clean the paint pipe 4 and sprayer 1.

At this time, by using a water-repellent and insulating material as the paint pipe 4, the thinner, etc. inside the paint pipe 4 is repelled and becomes dry, so even if high voltage is applied to the sprayer 1, the color will not change. No high voltage is applied to the replacement valve 6. Therefore, if a conductive material is used for the paint supply passage 14 and the pump 16 and paint tank 17 are brought to earth potential by, for example, contacting the earth with a ground rod or an air cylinder, the color change valve 6
Since the paint tank 17 can also be set to earth potential, operations such as removing the paint tank 17 can be performed safely even if a conductive paint is used.

In addition, when cleaning the space between the color change valve 6 and the sprayer 1 mentioned above, the color change valve 6 is automatically operated according to a predetermined program for high-speed cleaning in a short time of about 30 seconds or less. Since the paint pipe 4 is short, cleaning time can be shortened.

When cleaning of the sprayer 1 is completed as described above, the paint valve 22 of the second color change valve 7 is opened for a short time as shown in FIG.
The color is supplied to the sprayer 1 via a paint pipe 5. Thereby, preparations are made so that the object to be coated with B color can be coated immediately. On the other hand, since the paint tank 28 is placed on the insulating stand 29 by filling the paint pipe 5 with color B as described above (in this case, the paint tank 28
8 is not grounded), even if conductive paint is used as color B, high voltage is applied to the sprayer 1 and at the same time the color change valve 7 is connected via the paint in the paint pipe 5.
Sprayer 1 is installed in the paint supply passage 25, paint tank 28, etc.
A high voltage with the same potential is applied, which can prevent fires caused by sparks.

Furthermore, when the next object to be coated arrives from the above-mentioned state, the reciprocator R is operated again, high voltage is applied to the sprayer 1, and the paint valve 22 is opened as shown in FIG. 3D to spray the material. Spray B color paint from machine 1 and start painting.

On the other hand, since the paint pipe 4 has been cleaned and is electrically insulated, the insulation stand 1
8 through the A color paint tank 17, the thinner tank 30 is placed, and the pump 16 is driven to flow the thinner into the paint supply passage 14, pump 16, and paint valve 11 to clean the A color remaining inside these. (See Figure 3, G). After this cleaning is finished, insulating stand 1
The thinner tank 30 is removed from the tank 8, the C color paint tank 17 is placed thereon, the pump 16 is operated again, and the C color is circulated between the paint supply passage 14 and the paint valve 11.

By repeating the above-described operations, the first paint supply system consisting of the first paint supply passage 14, color change valve 6, paint pipe 4, etc., produces colors A and C.
A second paint supply system consisting of a second paint supply passage 25, a color change valve 7, a paint pipe 5, etc. supplies paints for colors B, D, F, etc.
By supplying paints of different colors, it is possible to sequentially spray paints of colors A, B, ...N from one sprayer 1.

Since the electrostatic coating method according to the present invention has been described in detail above, the cleaning time of the sprayer can be shortened with a simple configuration, and the preparation for painting the next color can be carried out by using the painting process of the previous color. You can improve your work efficiency. Additionally, if you program the paint pipes and sprayers to automatically clean them, you can further increase work efficiency. Moreover, it has many advantages, such as being able to use either conductive paint or insulating paint as the paint.

[Brief explanation of drawings]

FIG. 1 is an overall configuration diagram of an electrostatic coating apparatus used in the present invention, FIG. 2 is a sectional view of a color change valve, and FIG. 3 is an explanatory diagram of the operation of the coating process according to the present invention. 1... Sprayer, 3... High voltage generator, 4, 5...
...First and second paint pipes, 6,7...First and second color change valves, 8,19...Manifold, 9,2
0... Air valve, 10, 21... Thinner valve, 11,
22... Paint valve, 14, 25... First and second paint supply passages, 16, 27... Pump, 17, 28
...Paint tank, 30,31...Thinner tank.

Claims (1)

[Claims] 1. One sprayer that sprays paint while applying a high voltage, and first and second color changers that control the paint and cleaning fluid to be supplied to the sprayer. a valve, first and second paint pipes respectively connecting the sprayer and each color change valve, the first, second and color change valves, and a plurality of paint tanks for storing paints of a plurality of colors. and first and second paint supply passages respectively connected to one of the paint tanks, and after the painting of the previous color paint is completed, the first and second color change valves are connected to one of the paint tanks. The cleaning fluid is supplied to one of the color change valves used to supply the color change valve, one of the paint pipes, and the sprayer, and after this cleaning is completed, the next color change valve, which is supplied from the other paint supply passage, is supplied with cleaning fluid. The color paint is sprayed from the sprayer toward the object to be coated through the other color change valve and the other paint pipe, and the above-mentioned one color change valve,
After cleaning one paint pipe and sprayer, the previous color paint remaining in the one paint supply passage between one paint tank and one color change valve is cleaned, and after cleaning the previous color paint, the An electrostatic spraying method characterized in that color paints are successively circulated between one paint supply passage and one color change valve to prepare for spraying of the paints one after another. 2. After cleaning one color change valve, one paint pipe, and the sprayer used for painting the previous color, supply the next color paint from the other color change valve to the sprayer for a short time, and then supply the next color paint to the other paint pipe. The electrostatic coating method according to claim 1, wherein the electrostatic coating method is filled with a next color paint.