JP2000354804A - Coating apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress waste of coating in a filling process of a next color coating and reduce running cost by interposing a variable throttle valve in a discharge passage. SOLUTION: A coating gun 1 is provided with a trigger valve 9 for discharging a coating from a second feed passage 5 through the coating gun 1 and a first dump valve 11 for connecting the second feed passage 5 with a second discharge passage 10. The second discharge passage 10 is connected with a second cleaning valve 12 provided with a water valve 12a, a thinner valve 12b and an air valve 12c, and is also provided with a variable throttle valve 13 controlled by air pressure. A passage for inputting air from an air source 14 to the variable throttle valve 13 has a pressure regulator 15 interposed therein so that the opening of the variable throttle valve 13 can be changed by controlling air pressure by using the pressure regulator 15. By this constitution, even if a next color coating to be used has a low viscosity, waste discharge of the coating through the discharge passage 10 in a filling process is suppressed so that running cost can be reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a coating apparatus capable of performing color change coating.

[0002]

2. Description of the Related Art Conventionally, in a coating apparatus of this kind, as shown in Japanese Utility Model Publication No. 2526393, a washing step at the time of color change and a filling step of the next color paint are provided in a supply path for supplying a paint to a gun. A discharge path connected via a dump valve that opens in step is provided to discharge the washing waste liquid from the discharge path in the cleaning step, and to push out the air in the supply path to the discharge path in the filling step of the next color paint, thereby supplying the supply path. The paint is completely filled without leaving air. In addition, in terms of cycle time management,
The filling of the next color paint is performed in a fixed time.

[0003]

By the way, the viscosity may vary depending on the type of the paint, and therefore, the filling time of the next color paint is determined so that the supply path can be completely filled even with a high-viscosity paint. It is set according to the high viscosity paint. As a result, in the case of a paint having a low viscosity, the paint is supplied even after the completion of the air bleeding, and the paint is wastefully discharged from the discharge path.

[0004] In view of the above, it is an object of the present invention to provide a coating apparatus capable of suppressing waste of paint in a step of filling a next color paint and reducing running cost.

[0005]

In order to solve the above problems,
The present invention is directed to a coating apparatus having a discharge path connected to a supply path for supplying paint to a coating gun via a dump valve that opens in a washing step for color change and a filling step for a next color paint. A variable throttle valve is interposed in the road.

According to the present invention, when the next color paint is a low-viscosity paint, the amount of paint discharged from the discharge passage can be reduced by reducing the opening of the variable throttle valve.

[0007] A similar effect can be obtained even if a variable throttle valve is interposed in the supply path. However, in this case, air tends to remain in the supply path due to the biting of air by the variable throttle valve. On the other hand, in the present invention, since the variable throttle valve is interposed in the discharge path, there is no adverse effect due to air biting in the variable throttle valve.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows an electrostatic coating apparatus in which paint is applied by applying a high voltage from a coating gun 1 to be discharged.

This coating apparatus includes a plurality of paint valves 2a,
Water valve 2b for supplying water (W) as a cleaning liquid for water-based paint
A color change valve 2 having a thinner valve 2c for supplying a thinner (S) as a cleaning liquid for oil-based paint, an air valve 2d for supplying air (A), and a cylinder 3 capable of filling and extruding paint. Is provided. A paint supply source (not shown) that supplies paint at high pressure is connected to each paint valve 2a. When any one of the paint valves 2a is opened, paint from the corresponding paint supply source becomes the first paint valve. Cylinder 3 via supply path 4
Supplied to

The cylinder 3 has a built-in piston 3b which is advanced and retracted by a servomotor 3a. The cylinder 3 is filled with paint from the first supply passage 4 when the piston 3b is retracted, and the cylinder 3 is extended when the piston 3b advances. Supplies the paint to the coating gun 1 via the second supply path 5.

The first supply passage 4 has a cylinder 3 and a color change valve 2
And an insulating mechanism 6 for electrically insulating between the two. The insulating mechanism 6 includes a first switching valve 6a on the color switching valve 2 side, a second switching valve 6b on the cylinder 3 side, and a tube 6c made of an insulating material between the switching valves 6a and 6b. In addition, in relation to the insulating mechanism 6, a first cleaning valve 7 provided with a water valve 7a, a thinner valve 7b, and an air valve 7c, and a first discharge path 8 are provided. The first switching valve 6a has a state in which the upstream portion 4a of the first supply path 4 connected to the color changing valve 2 is connected to the tube 6c, and a state in which the connection is cut off and the first washing valve 7 is connected to the tube 6c. And can be switched freely.
The switching valve 6b is switchable between a state in which the downstream portion 4b of the first supply path 4 connected to the cylinder 3 is connected to the tube 6c and a state in which the connection is cut off and the first discharge path 8 is connected to the tube 6c. It is.

The paint gun 1 has a trigger valve 9 for discharging paint from the second supply passage 5 from the paint gun 1 and a first dump valve 11 for connecting the second supply passage 5 to a second discharge passage 10. Is provided. A second cleaning valve 12 having a water valve 12a, a thinner valve 12b, and an air valve 12c attached thereto is provided in the second discharge path 10.
Is connected, and the variable throttle valve 1 is controlled by air pressure.
3 are interposed. A pressure regulator 15 is provided in a passage for inputting air from the air source 14 to the variable throttle valve 13, and the opening of the variable throttle valve 13 is varied by controlling the air pressure by the pressure regulator 15. Further, the upstream portion 4a of the first supply path 4
Is connected to a third discharge passage 17 via a second dump valve 16.

At the time of painting, first, the upstream portion 4a and the downstream portion 4b of the first supply path 4 are connected via the tube 6c by the first and second switching valves 6a and 6b. The paint is supplied from the valve 2 to the first supply path 4, and the cylinder 3 is filled with the paint. Next, the first cleaning valve 7 is connected to the first discharge path 8 via the tube 6c by both the switching valves 6a and 6b, and in this state, the cleaning liquid (water or thinner) is supplied from the first cleaning valve 7 to the tube. The paint in 6c is washed away, and then air is supplied from the first cleaning valve 7 to dry the inside of the tube 6c with air, thereby ensuring electrical insulation between the two switching valves 6a and 6b.

Next, the trigger valve 9 is opened, and at the same time, the piston 3b is advanced at a constant speed by the servomotor 3a to push the paint from the cylinder 3 to the second supply path 5 at a constant flow rate. The paint is discharged from the paint gun 1 by pressing. At this time, a high voltage is applied to the paint in the coating gun 1, but since the electrical insulation is secured in the tube 6c of the insulating mechanism 6 as described above, even if the paint is conductive such as a water-based paint. No voltage leakage occurs, and good electrostatic coating is achieved.

When the same paint is refilled into the cylinder 3 after the paint is completely extruded from the cylinder 3, both switching valves 6
a, 6b connect the upstream portion 4a and the downstream portion 4b of the first supply passage 4 via the tube 6c, open the second dump valve 16 and connect the third discharge passage 17 to the upstream portion 4a. In this state, the paint remaining in the cylinder 3 is sent back to the first supply path 4 to push out the air in the tube 6c to the third discharge path 17, and then the second dump valve 16 is closed to close the color. The paint is supplied from the replacement valve 2 to the first supply path 4.

When the paint is fed back from the cylinder 3 to the first supply passage 4, the pressure of the paint to be fed back is made relatively low by controlling the torque of the servomotor 3a, and the air in the tube 6c is fed into the paint. Extrude slowly to avoid biting. Further, when the paint is a low-viscosity paint, the back-feed pressure is set lower than when the paint is a high-viscosity paint, and the paint is prevented from being wastefully discharged from the third discharge path 17.

After the extrusion of the paint from the cylinder 3 is completed, when switching colors to fill the cylinder 3 with another paint, the two switching valves 6
a, 6b connect the upstream part 4a and the downstream part 4b of the first supply path 4 via a tube 6c.
Supply the cleaning liquid (water or thinner) from the first supply path 4
Then, the paint in the cylinder 3 and the second supply path 5 is washed away. Then, at the beginning of the cleaning, the trigger valve 9 is opened to clean the discharge path of the coating gun 1, and then the trigger valve 9 is closed and the first dump valve 11 is opened to discharge the cleaning waste liquid to the second discharge path. Discharge to 10 Next, air is supplied from the color changing valve 2 to scavenge the first supply path 4, the cylinder 3, and the second supply path 5, and then the next color paint is supplied from the color changing valve 2. According to this, the first
The paint is filled in order while extruding air into the supply path 4, the cylinder 3, and the second supply path 5, and when the next color paint is completely filled up to the downstream end of the second supply path 5, the first dump valve 11 is closed. The valve is filled to complete the filling of the next color paint.

The filling time is set to a time required for filling the paint having the highest viscosity. For the paint having a low viscosity, the paint is wastefully discharged from the second discharge passage 10 even after the filling is completed. Therefore, when the next color paint is a low-viscosity paint, the opening degree of the variable throttle valve 13 is reduced and the second discharge path 10
To reduce the discharge of paint from

After filling with the next color paint, a washing liquid (water or thinner) is supplied from the second washing valve 12 to wash away the paint in the second discharge path 10, and then air is supplied from the second washing valve 12. Then, the second discharge path 10 is scavenged to complete the color changing operation.

Although the embodiment in which the present invention is applied to the electrostatic coating apparatus having the cylinder 3 and the insulating mechanism 6 has been described above, a single supply path having no insulating mechanism or cylinder from the color changing valve to the coating gun is provided. The present invention can be similarly applied to a coating apparatus that supplies a coating material through the apparatus.

[0021]

As is apparent from the above description, according to the present invention, even if the next color paint is a low-viscosity paint, it is possible to prevent the paint from being wastefully discharged from the discharge path in the filling step. And running costs can be reduced.

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing an example of the device of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Painting gun 5 Supply path 10 Discharge path 11 Dump valve 13 Variable throttle valve

Continued on the front page (72) Inventor Toshiyuki Kubo 1-10-1 Shinsayama, Sayama City, Saitama Prefecture Honda Engineering Co., Ltd. (72) Inventor Osamu Kageyama 1-10-1 Shinsayama 1 Sayama City, Saitama Prefecture Honda Engineering Stock In-company F term (reference) 4F035 AA03 BA05 BA12 BA15 BC06

Claims (1)

[Claims] 1. A coating apparatus having a discharge path connected to a supply path for supplying paint to a coating gun through a dump valve opened in a washing step for color change and a filling step of a next color paint, A coating device, comprising a variable throttle valve interposed in a discharge path.