JP3206835B2 - Quantitative paint supply device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ON / OF coating gun.
The present invention relates to a circulating quantitative paint supply device that switches between supplying the paint pumped up by a gear pump to the paint gun and returning the paint to the tank by switching the direction switching valve in conjunction with the F operation. The present invention relates to a quantitative paint supply device improved so that a prescribed paint supply pressure can be obtained instantaneously during an ON operation.

[0002]

2. Description of the Related Art Conventionally, as a circulation type quantitative paint supply apparatus using a gear pump, as shown in FIG.
By switching the on / off valve c with an air signal for turning on / off the coating gun a to switch the supply of the paint to the coating gun a and to return the paint to the tank b, or FIG. As shown in (1), there is known a method in which the direction of the three-way valve d is switched to switch between supply and reflux of the paint.

[0003]

SUMMARY OF THE INVENTION
When the paint gun a is turned off and the paint is returned to the tank b, the on-off valve c is opened or the three-way valve d is opened.
Since the reflux side of the paint is open, the pressure of the paint becomes extremely low.
Accordingly, when the on-off valve c is closed or the three-way valve d is switched to supply the paint to the coating gun a,
There is a drawback that a delay of several seconds occurs when the paint pressure reaches the specified value and a constant discharge amount is obtained. Above all, paint gun O
In automatic coating in which N.OFF is switched in seconds, it has been difficult to obtain a stable paint discharge amount.

[0004]

As a means for solving the above-mentioned problems, a quantitative paint supply device of the present invention adjusts the flow rate of the paint in the reflux path so that the pressure at the time of the paint reflux is adjusted. A back pressure valve is provided to match the pressure of the feed path .

[0005]

According to the present invention, a pressure gauge is provided in each of the feed path and the return path, so that the paint pressure at the time of supply to the coating gun and the paint pressure at the time of return to the tank can be detected. First, supply paint to the paint gun and check the paint pressure at the time of supply.
The degree of opening of the back pressure valve interposed in the return path is adjusted so that the paint pressure in the return path matches the paint pressure in the feed path.

As a result, the paint pressure when the paint gun is turned off to recirculate the paint is always kept at the same level as the specified paint pressure at the time of supply, and then the paint gun is turned on and the directional control valve is turned off. When the paint is supplied to the paint gun instead, the paint pressure reaches the specified value instantaneously.

[0007]

In other words, according to the present invention, by adjusting the back pressure valve, even when the paint is refluxed, the paint pressure is increased to a specified pressure substantially matching the paint pressure at the time of supply, and the standby state is maintained. Therefore, when the supply is switched to the supply of the paint to the coating gun, the supply pressure instantaneously reaches a prescribed value with good response, and a stable discharge amount can be obtained from the beginning.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to FIGS. In FIG. 1, reference numeral 1 denotes a feed path for pumping the paint in a tank 2 by a gear pump 3 and feeding the paint to a coating gun 4.
A three-way valve 5 that is switched in conjunction with an air signal for controlling N-OFF is interposed, and a recirculation path 6 is connected to a port on one side of the three-way valve. Then, the three-way valve 5 is switched to one side, and the paint is supplied to the coating gun 4 through the feed path 1, and when the coating gun 4 is turned off,
The three-way valve 5 is switched to the other side, so that the paint is returned to the tank 2 by the return path 6.

The feed path 1 is provided with a first pressure gauge 7 for detecting a paint pressure P ₁ supplied to the coating gun 4, and the return path 6 is provided with a return path 6. the back pressure valve 8 in order to increase the coating pressure during reflux by adjusting the paint flow, and a second pressure gauge 9 for detecting the paint pressure P ₂ of the recirculation passage 6 is provided.

As shown in FIG. 2, the opening of the valve opening 13 of the back pressure valve 8 is determined by the balance between the control air pressure supplied to the back side of the diaphragm 10 and the elasticity of the spring 12 mounted on the valve body 11. The flow rate is adjusted by changing the pressure, and the air pressure control type flow rate adjusting valve is suitable. The second pressure gauge 9 is connected to the front side of the diaphragm 10 to detect the paint pressure in the return path 6. You can do it.

Next, the operation of this embodiment will be described. First, the coating gun 4 is turned on, the paint is supplied to the coating gun 4 by switching to one side of the three-way valve 5, and the paint is sprayed. The rotation speed of the gear pump 3 is adjusted so that the discharge amount becomes a predetermined amount. adjust. When the discharge amount reaches a predetermined value, the paint pressure P ₁ at the time of supply is confirmed by looking at the first pressure gauge 7.

Next, the paint gun 4 is set to 0FF and the paint is returned to the tank 2 by switching to the other side of the three-way valve 5,
Changing the control air pressure applied to the back pressure valve 8 which is interposed in the recirculation passage 6, the paint pressure P ₂ of the return passage 6 indicated by the second pressure gauge 9 is coincident with the paint pressure P ₁ of the sheet sending passage 1 Adjust as follows.

As a result, the paint pressure when the paint is refluxed is always kept at the same level as the prescribed paint pressure at the time of supply, and the paint pressure is immediately regulated when the paint is supplied to the coating gun 4 next time. Value, and a predetermined discharge amount is obtained from the beginning.

[0014] or when changing the discharge amount of paint, Tara kinds river connexion viscosity of the paint discharge amount even at the same supply pressure P ₁ of the coating material by differ such changes and summer, again adjusting the control air to be applied to the back pressure valve 8 to, it is sufficient to match the paint pressure P ₂ at reflux in a new supply pressure P _1.

The present invention can cope with the case where the paint as shown in FIG. 3 is simultaneously supplied to a plurality of coating guns 4a, 4b, 4c only by attaching one back pressure valve 8 to the return passage 6. it can.

When the present invention is applied to, for example, a color change coating system in which two kinds of paints are alternately blown, as shown in FIG. 4, each paint is separately applied by a color change valve 15 comprising a three-way valve. While it is possible to supply the paint to the gun 4, while other paint is being supplied from each color changing valve 15, or
The circulation paths 6 for returning the paint to the tank 2 during the washing before the color change are drawn out, and a back-pressure valve 8 similar to that described above is interposed in each of the circulation paths 6 to form a complicated system. Can be handled without any problems.

If the back pressure valve 8 is an air pressure control type flow control valve shown in FIG. 2, the control air pressure applied to the back pressure valve 8 can be set to 0 to immediately open the back pressure valve 8 completely. For example, when the washing is performed from the gear pump 3 to the return path 6 for changing the paint, a large amount of the cleaning liquid can be circulated through the return path 6 for efficient cleaning.

[0018]

[Brief description of the drawings]

FIG. 1 is a configuration diagram of an embodiment of the present invention.

FIG. 2 is a sectional view of a back pressure valve.

FIG. 3 is a configuration diagram of an example in which the present invention is applied to a simultaneous supply system to a plurality of guns.

FIG. 4 is a configuration diagram of an example in which the present invention is applied to a color change coating system.

FIG. 5 is a configuration diagram of a conventional example.

[Explanation of symbols]

1: feeding path 2: tank 3: gear pump 4: painting gun 5: three-way valve (directional switching valve) 6: recirculation path 7, 9:
Pressure gauge 8: Back pressure valve 15: Color change valve (directional change valve)
c: On-off valve (directional switching valve)

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁷ , DB name) B05B 12/00-13/06

Claims (1)

(57) [Claims] 1. A recirculation path for returning paint to the tank via a three-way valve is connected to a feed path for pumping the paint in the tank by a gear pump and supplying the paint to the coating gun. By switching the three-way valve in conjunction with the operation, in a quantitative paint supply device configured to supply the paint to the coating gun and to return to the tank, the return path, the return path, the flow rate of the return path By adjusting, the pressure at the time of the reflux of the paint coincides with the pressure of the feed path.
A constant-quantity paint supply device having a back pressure valve interposed therebetween.