JPH10272389A - Method and device for replacing coating material in static powder coating - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method and a device capable of facilitating replacement of a section to be replaced at the time of replacing a coating material and cleaning the in side of a coating booth safely in a short time, in a static powder coating for handling powder coating materials of different colors or resins. SOLUTION: A collection through 24 for receiving a coating material discharged from a coating booth 21 and a coating material accumulating section in the lower section of a cyclone 27 are set replaceably based on the classified color and resin of the coating material, and at the time of replacing a coating material, the coating material remaining in spray guns 22 and 22' and the coating booth 21 are dry cleaned, and the section to be replaced is removed and the coating material is recovered, and then the coating booth 21 and the cyclone 27 main body are washed with hot water, and a replacing section for the required coating material is attached after the cleaning section is dried.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for changing powder in electrostatic powder coating in which powder coatings having different colors and / or resins are treated as electrostatic powder coatings and can be easily changed in a short time. .

[0002]

2. Description of the Related Art Electrostatic powder coating does not discharge a solvent,
In recent years, it has gained an important position in the field of painting because of its environmental and economic advantages, such as the ability to collect and reuse paints that have not been applied during spraying. FIG. 6 is a plan view for explaining the configuration of a conventional general electrostatic powder coating line. An object to be coated (hereinafter referred to as a work) is loaded on a hanger of the conveyor 1 at a point A on the circulation conveyor 1 and is carried into the coating booth 2. The painting booth 2 has two areas for spray-painting the charged powder coating material on the work from both sides in the front and rear directions of the work in the transport direction. In each spray coating area, a plurality of spray guns 3 and 7 for spray-coating the powder paint under the control of the coating machines 4 and 8 are provided, and these spray guns 3 and 7 are respectively reciprocator. 5,
9 reciprocates up and down, so that the entire surface of the work continuously conveyed on the conveyor 1 is sequentially painted. The coated work then enters a baking furnace 19, where it is heated at a predetermined temperature and for a predetermined time to form a film by a melting or thermosetting reaction, and then naturally cooled on the conveyor 1 and unloaded at point B.

[0003] Each spray gun 3 of the painting booth 2
On the side opposite to 7, suction ports 10, 10 'connected to exhaust fans 14, 18 are provided, respectively, for sucking oversprayed paint and sending it to cyclones 12, 16.
Most of the paint that has passed through the cyclones 12 and 16 is separated and collected, and fine powder is captured by bag filters 13 and 17 and exhausted through exhaust fans 14 and 18. The paint recovered in this way is added to a paint supply tank provided in the coating machines 4 and 8, and is reused.

[0004]

As described above, powder paints can significantly increase paint yield by recovering overspray paints as compared with solvent paints. However, when powder paints of different colors or different types of resin are applied alternately on the same painting line, not only the paint system but also the paint booth and the collection system must be thoroughly cleaned and recalled when changing paint. It is necessary to prevent foreign paints from being mixed into the paint. In other words, the particles of the paint have a particle size almost close to the film thickness, have a high viscosity even when melted by heating, and do not disperse as in the case of solvent paint. Furthermore, when paint particles of different resins are mixed (for example, acrylic paint is mixed in epoxy paint)
In the baking cooling process, so-called cissing occurs due to the respective flow temperature characteristics, surface tension, compatibility, etc.
A crater is generated with mixed paint particles as nuclei. The size of the craters is larger than the particle size of the mixed paint and reaches 1 to 2 mm, and when they occur collectively, they take on a satin-like shape.

[0005] As a result of the above, the recovered paint causes defective products in the coating, so that the recovered paint cannot be reused. Cleaning of the entire coating apparatus every time paint is changed in order to prevent such contamination of the recovered paint results in stopping the operation of the coating line for a long time, and the operation rate of the equipment is significantly reduced.

[0006] In order to eliminate the operation stoppage at the time of changing the paint, a paint line may be separately provided for each paint, but the capital investment is increased and the cost merit of the paint recovery is lost.
For this reason, a method of exchanging only the recovery system at the time of changing paint has been performed. For example, there is a method in which the entire recovery system using a cassette filter is unitized and prepared for each color, and a required recovery unit is attached to a painting booth when changing colors.
This method is suitable for small-capacity small-sized coating equipment because paint collection is performed only by a filter, but is not suitable for large-capacity coating lines.

[0007] The present applicant has proposed an electrostatic powder coating apparatus as disclosed in Japanese Patent Application Laid-Open No. HEI 8-117647 in which color change can be easily performed in a short time. The schematic configuration is as follows: a coating booth having an inner wall made of a smooth insulating plastic material, forming a discharge port at the lower end of a bottom having a Y-shaped cross section, and a receiving port airtightly connected to the discharge port. Has,
A cylindrical collecting trough detachably connected to a suction duct having one end closed and the other end leading to a cyclone, and a cyclone capable of detachably separating a lower paint depositing section,
A plurality of the collecting troughs and the paint depositing section are provided for each color. Further, in order to facilitate the cleaning work, the painting booth is suspended on a rail provided above the painting booth, and stands by outside the painting booth during operation of the painting apparatus, and a worker is put on the painting booth during cleaning. There is an electric gondola running inside.

According to the above-described coating apparatus, since the inner wall of the coating booth is formed of an insulating material, no image charge is generated by the charged particles. Therefore, the charged paint particles generate electrostatic attraction between the wall and the wall. Does not occur. Further, since the wall has a smooth shape, it can be easily cleaned by wiping with an air blow or a mop. Further, by running the gondola as a work platform, the cleaning operation can be performed quickly and safely. Among the collection systems, paint does not adhere to the suction duct or cyclone main body where the flow velocity is high, and the bag filter is difficult to clean. Do not. Therefore, the change in color change is limited to the collection trough and the paint accumulation portion of the cyclone. All of these exchange parts are moved by a cart and can be exchanged in a short time if they can be set at the exchange position. In this way, mixing of different colors into the recovered paint is
It can be prevented to the extent that there is no practical problem.

However, when the type of resin constituting the paint is different, as described above, the influence of the contamination is even greater, and it is difficult to completely prevent the influence even by the above-mentioned coating apparatus.

SUMMARY OF THE INVENTION The present invention has been made under the above circumstances, and an object of the present invention is to provide an electrostatic powder coating system using powder coating materials having different colors and / or resins, in which a replacement portion when changing paints is used. It is an object of the present invention to provide a method and an apparatus which facilitate replacement and can clean the inside of a painting booth safely and in a short time.

[0011]

SUMMARY OF THE INVENTION The present invention relates to a method for changing the paint of electrostatic powder coating which handles powder paints of different colors and / or resins. The collection trough for receiving the paint and the paint depositing section below the cyclone can be exchanged for each paint color and resin.When changing the paint, first stop the supply of paint to the spray gun and install it in the paint hose and the spray gun. The paint remaining in the paint booth is air-purged, and the paint booth is dry-cleaned using an electric gondola running in the paint booth. Then, the suction fan is stopped and the collection trough and the paint depositing unit are connected. The paint booth is released and the paint is collected. Then, the entire inside of the coating booth is washed with hot water by hot water shower nozzles arranged in front and behind the gondola, and the cycle After the internal emission body is dried and cleaning portion and warm water washing is achieved by coupling the collection trough and paint deposition unit for the required paint.

[0012] The above object of the present invention is also directed to a coating booth in which the inner wall surface is made of a smooth insulating plastic material and has a Y-shaped cross section and a discharge port formed at a lower end of a downward slope. A cylindrical collection trough having a receiving port that is airtightly connected, one end of which is closed and the other end of which is detachably connected to a suction duct that leads to the cyclone, and a cyclone that can detachably separate a lower paint depositing section, It has an electric gondola that waits outside the booth during painting, runs inside the booth when changing paint, and has a hot water shower nozzle lined up on the front and back surfaces, and the collection trough and the paint depositing unit are divided into a plurality by color and resin. Achieved by providing.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In order to collect paint remaining in a booth after painting is completed, dry cleaning such as wiping with an air blow or a mop is essential. Suction is taken from the outlet at the bottom of the booth. However, because the inside of the painting booth is large, some of the suspended paint particles cannot get on the airflow toward the discharge port and settle again in a place with a low flow velocity, and as a result, the amount of collection decreases even if time is spent for cleaning On the other hand, it is extremely difficult to eliminate minute paint residues. From the above, in the present invention, the dry cleaning and the wet cleaning are used in combination, the dry cleaning is completed in a short time in consideration of the paint collection efficiency, and the cleaning of minute residual paint which is a contamination source is performed with hot water washing. I did it. As a result, the paint flows out without being scattered, and complete cleaning can be performed. In addition, paint particles that are electrostatically attached, such as inside the cyclone body, are completely eliminated by being washed off with water. The use of warm water for washing has the advantage that the washing part is dried quickly.

Hereinafter, embodiments of the present invention will be specifically described with reference to the drawings.

FIG. 1 is a view showing a schematic structure of the present invention at the time of painting. A workpiece 20 conveyed by a conveyor is charged with powder charged by spray guns 22 and 22 ′ on both sides while passing through a painting booth 21. The paint is spray painted. At this time, the overspray paint which is not applied to the work 20 is formed into a cylindrical collecting trough 24 which is exchangeably attached to a lower portion thereof through an outlet 23 which is formed in a Y-shaped cross section and which is continuous with a slope at the bottom of the booth. Sucked into. One end of the cylinder of the collection trough 24 is closed, and the other end is detachably connected to a suction duct 26 that suctions by driving a suction fan 25, and the paint sucked into the collection trough 24 is sent to a cyclone 27 together with air. . Cyclone 2
7, the main body and the lower paint depositing section 28 can be separated.
9 together with a color and resin-based mobile collection unit 50. The air that has exited the cyclone 27 catches the fine paint particles that have not been collected by the bag filter 30 and is exhausted from the outlet of the suction fan 25.

The replacement collection trough 241 is mounted on a cart 242 as shown in FIG. 1 and is placed at a fixed position on a table lifter 244 installed in the pit. Here, when the table lifter 244 is raised, the receiving port 243 and the connection end of the collection trough 241 are set at the joint positions with the discharge port 23 and the suction duct 26, respectively, and can be connected by a simple method using a one-touch fitting or the like. The collection unit 50 includes a frame 52 mounted on a cart 51, a paint stacking section 28 supported by a support member 521 provided on the upper portion of the frame 52 so as to be able to move up and down, and discharge from the paint stacking section 28. And a recovered paint tank 29 for receiving the recovered paint to be recovered. To replace the collection unit 50, the collection unit 50 is carried below the cyclone body, and the support member 251 is operated by the operation of a cylinder (not shown).
Is raised, and the flange provided at the upper end of the paint depositing section 28 is brought into contact with the flange 271 on the cyclone main body side, and is joined using a joining fitting.

FIG. 2 is a view showing the appearance of the coating booth 21 of the present invention when the paint is changed, FIG. 2 (A) is a cross-sectional view in the traveling direction of the conveyor, and FIG. 2 (B) is a cross-sectional view of the side.
The material of the inner wall 32 of the coating booth 21 is made of an insulative plastic material such as hard vinyl chloride or FRP, and is formed with a gentle curved surface that does not generate powder or water pools. Opening doors 211 and 212 are provided before and after the painting booth 21, and a cut portion 35 serving as a passage for the work hanger 33 and the gondola hanger 34 is provided on the ceiling. In addition, a flange 231 for connecting the collection trough 24 to both outer sides of the outlet 23 having a vertical side surface is provided at a central portion of the bottom portion having a downward slope with a Y-shaped cross section.
Articles are provided.

The electric gondola 31 has two rails 341.
And run in the forward and reverse directions by a drive motor (not shown). Inner walls 32 are provided on the front and rear surfaces of the gondola 31, respectively.
Also, shower pipes 361 and 362 in which shower nozzles 36 for cleaning the doors 211 and 212 are arranged. The hot water supplied to the shower pipes 361 and 362 is heated by the boiler 37 and kept at a predetermined temperature in a hot water tank 38 and sent to a hot water hose 40 by a pump 39 as shown in FIG. The hot water hose 40 is connected to shower pipes 361 and 362 from above the gondola 31 via a tension portion 41 provided in the middle. Although the tension roll 411 is used as the tension portion 41 in the drawing, a reel winding method may be used.

In the electrostatic powder coating apparatus as described above,
The paint change operation is performed in the following order. First, the supply of the paint to the spray guns 22 and 22 'is stopped, and the paint in the paint hose and the gun is air-purged into the painting booth 21 by compressed air. Next, when the worker gets on the gondola 31 at the position (1) which is the standby position and enters the painting booth 21, the opening / closing doors 211 and 212 of the painting booth 21 are closed and the gondola 31 travels slowly. ,
The operator cleans the peripheral wall in the coating booth 21 using an air nozzle or a mop, and the gondola 31 reciprocates in the coating booth 21 to complete the dry cleaning. Then, the doors 211 and 212 are opened, and the gondola 31 is returned to the original position (1). The dry cleaning using an air nozzle, a mop, or the like may be performed automatically or by remote control.

FIG. 3 shows the configuration in this case in correspondence with FIG. 2B. The shower nozzle 36 is connected to an air nozzle 36A, and the shower pipes 361 and 362 are connected to the air pipe 36.
1A and 362A, the hot water hose 40 also serves as the pneumatic feeding hose 40, and the pump 39 and the pneumatic feeding hose 4
The switching valve 43 is connected between the air conditioner and the compressor valve 0 so that air can be sent from the compressor 42 through the switching valve 43. Then, the drive goes into the painting booth 21 with the gondola 31,
Once stopped at the position (2) near the entrance, the door 211
And 212 are closed, and pressurized air is blown out from the air nozzle 36A of the air pipes 361A and 362A.
In this state, the gondola 31 advances slowly, temporarily stops at the position (3) near the exit, and returns to the position (2) again. Then, the compressor 42 is stopped, and the compressed air is stopped. Next, after switching the switching valve 43 for a hot water shower, the process proceeds to a hot water shower cleaning step.

When the dry cleaning in the painting booth 21 is completed, the operation of the suction fan 25 is stopped, and the empty truck on the table lifter 244 is raised to the receiving position of the collection trough 24 to be connected to the discharge port 23 and the suction duct 26. Is disengaged, and the collection trough 24 is lowered on a carriage and moved to a storage location. In addition, the collection unit 50 is released from the connection with the cyclone main body, and the operation of the cylinder causes the paint accumulation unit 28 to operate.
After the flange surface is lowered, it is moved to the storage location, and the paint collection is completed.

Next, when the gondola 31 waiting at the position (1) enters the painting booth 21 again and stops at the position (2) near the entrance, the doors 211 and 212 are closed, and the shower pipes 361 and 362 are closed. Shower nozzle 36
Spouts a hot water shower from. Gondola 31 in this state
Progresses slowly, temporarily stops at the position (3) near the exit, and returns to the position (2) again. Then, the pump 39 is stopped to stop jetting of the shower, the doors 211 and 212 are opened, and the gondola 31 is returned to the position (1). At this time, the washing water flowing out from the outlet 23 may be drained using a temporary drain trough.

In cleaning the cyclone 27, the internal structure of the cyclone body is simple, so that it can be easily cleaned using a manual shower hose. However, when the exhaust capacity of the suction fan 25 is large, the cyclone 27 becomes large. Become
Since the height is extremely high, the cleaning operation becomes difficult. In such a case, a plurality of small cyclones are used in parallel.
For example, if a multi-separator or the like is used, the height is low, the space is small, and the work is easy.

The temperature of the hot water used for the hot water washing is preferably as high as possible in order to speed up the drying of the washed portion. However, if the temperature exceeds the softening point of the plastic material, which is the structural material of the coating booth 21, the temperature of the residual water generated during the processing is increased. In some cases, deformation due to internal stress or thermal strain during use during installation or use may occur, so that the material used is subject to temperature restrictions. Normally, it is safe if the temperature of the hot water does not exceed 60 ° C.

After the washing portion has been dried in this way, the collection trough 241 and the collection unit 50 for the paint to be used for the next coating are carried from the respective storage locations to the respective mounting positions and combined, and all the paint changing operations are performed. finish.

Although the drying time is shortened by using hot water, if it is desired to eliminate the waiting time for drying at the painting booth, two painting booths are prepared, and one of the painting booths is operated and the painting booth is operated. And the other one may be dried off-line. FIG. 4 shows one of the specific examples. The first booth 61 used for the previous coating on the conveyor line 60 is washed with warm water, and then, along with the rack, is mounted on the rail 6.
11 and moved to the drying area. On the other hand, the second booth 62, which has been standby-dried in the drying area, runs on the rail 621, is inserted into the conveyor line 60, and is used for the next coating.

FIG. 5 shows another specific example.
A power and free conveyor is used for the conveyor line 60, and a first booth 61 and a second booth 62 are arranged in series. In the area of each painting booth, bypasses 613 and 623 are provided as shown in FIG.
2. The path of the free line is selected by switching P3, and the power line between each point is divided and driven. By doing so, the first booth 6
When using No. 1, the work conveyed by the conveyor line 60 takes the path shown by the solid line in the figure,
When the second booth 62 is used, a path indicated by a broken line in the figure is taken.

In the application of the present invention, when only the color of the paint is changed, the above-mentioned warm water washing step can be omitted.

[0029]

As described above, according to the method and apparatus for changing paint in electrostatic powder coating according to the present invention, dry cleaning and wet cleaning can be performed not only when the color of the paint but also the type of resin is changed. Is provided, there is no danger that other paints will be mixed into the recovered paint, and the paint can be changed quickly and safely without lowering the recovery efficiency.

[Brief description of the drawings]

FIG. 1 is a configuration diagram for explaining a schematic configuration of the present invention at the time of painting.

FIG. 2 is a view showing a state of a painting booth of the present invention when a paint is changed.

FIG. 3 is a side view showing another embodiment of the present invention.

FIG. 4 is a diagram showing a specific example in which two painting booths are used alternately.

FIG. 5 is a diagram showing another specific example in which two painting booths are used alternately.

FIG. 6 is a plan view illustrating a schematic configuration of a conventional electrostatic powder coating line.

[Explanation of symbols]

 Reference Signs List 20 Workpiece 21 Painting booth 22, 22 'Spray gun 23 Discharge port 24, 241 Collection trough 25 Suction fan 26 Suction duct 27 Cyclone 28 Paint accumulation section 29 Collection paint tank 30 Bug file 31 Electric gondola 36 Shower nozzle 361, 362 Shower pipe 38 Hot water tank 39 Pump 40 Hot water hose 41 Tension part 50 Collection unit

Claims (7)

[Claims] A paint trough for receiving paint discharged from a coating booth and a paint depositing portion below a cyclone can be exchanged for each paint color and resin.
First, the supply of paint to the spray gun is stopped, paint remaining in the paint hose and the spray gun is purged by air into the paint booth, and the inside of the paint booth is dried using an electric gondola running in the paint booth. After cleaning
Stop the suction fan, release the connection between the collection trough and the paint depositing section and perform paint recovery, and then wash the entire inside of the painting booth with hot water shower nozzles arranged in front and behind the gondola, A method of changing paint in electrostatic powder coating, wherein the inside of the cyclone main body is washed with warm water and the washed portion is dried, and then a required paint collecting trough and a paint depositing portion are connected. 2. The method according to claim 1, wherein the temperature of the hot water for washing the inside of the booth with hot water does not exceed 60 ° C. as high as possible. 3. The paint change in electrostatic powder coating according to claim 1, wherein in the hot water washing of the coating booth, the washing water flowing out from the booth outlet is drained using a temporary drainage trough. Method. 4. The electrostatic powder coating according to claim 1, wherein two painting booths are prepared, one of which is used for a painting line in operation, and the other is dried off-line. Paint change method in Japan. 5. A coating booth whose inner wall surface is made of a smooth insulating plastic material, has a Y-shaped cross section, and forms a discharge port at a lower end of a downward slope, and a receiving port which is hermetically connected to the discharge port. A cylindrical collection trough having one end closed and the other end detachably connected to a suction duct leading to a cyclone, a cyclone capable of detachably detaching a lower paint deposition portion, and the painting booth during painting. Wait outside,
An electric gondola having a hot water shower nozzle arranged on the front and rear surfaces while running in the coating booth at the time of changing paints is provided, and a plurality of the collecting troughs and the paint depositing units are provided for each color and resin. Paint changer for electrostatic powder coating. 6. The electrostatic powder according to claim 5, comprising two painting booths, wherein each of the painting booths can move on a rail together with a gantry to a painting line or a drying area. Paint changer for body painting. 7. The coating material for electrostatic powder coating according to claim 5, wherein two coating booths are arranged in series on a coating line, and each of the coating booth sections is provided with a bypass that can be switched at a point. Replacement device.