JP3645718B2 - Paint supply device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a coating material supply apparatus for supplying a liquid coating material to a coating gun under pressure and discharging the coating material onto an object to be coated.
[0002]
[Prior art]
When supplying paint to a bell-type or air-spray-type paint gun to which a voltage is applied, as shown in FIG. As shown in FIG. B, a tank pressurizing system for discharging or a paint circulation path 4 incorporating an air pump 6 and an accumulator 7 is connected to the paint tank 5, and the paint gun 3 is branched from the paint circulation path. The paint circulation system is well known.
[0003]
[Problems to be solved by the invention]
In the former case, it is easy to smoothly supply the paint, but there is a problem that the paint is deposited in the supply path when the painting is stopped, and the coating quality is deteriorated particularly in the case of a small amount of painting work with interruption. In the latter case, this drawback is eliminated by the circulation of the paint by the air pump. However, since the paint pulsation occurs due to the reciprocating stroke, it is necessary to follow the accumulator to provide a smoothing action. In addition, since the paint is circulated and discharged from the paint gun, the amount of paint is increased, the pipe diameter must be increased correspondingly, and the pump pressure must be increased accordingly. Furthermore, there is also a problem of quality deterioration due to the circulation of the paint itself with respect to the paint containing the volatile material.
[0004]
SUMMARY OF THE INVENTION In view of the above, an object of the present invention is to provide a paint supply apparatus that can suppress paint deterioration associated with the interruption of paint supply and supply the paint to a paint gun by a tank pressurization method.
[0005]
[Means for Solving the Problems]
In order to achieve this object, according to the present invention, an air pump that operates when painting is stopped is incorporated between a paint discharge port and a paint return port of a paint feeding tank that feeds paint by air pressurization during painting. Connected to the air pump via a valve that opens to bypass the air pump during painting, and a paint gun is connected to the paint circuit on the downstream side, and further downstream The paint circulation path is provided with a valve for opening the paint circulation path when painting is stopped.
[0006]
At the time of painting, the paint is pumped from the paint pumping tank by air pressurization, and the air pump is bypassed by a bypass path and supplied to the coating gun. At that time, the paint circulation path downstream of the paint gun is closed by a valve, and the paint is not circulated to the paint pressure tank. When painting is stopped, the bypass passage is closed and the air pump is operated, so that the paint circulates to the paint pressure feed tank through the open paint circulation path.
[0007]
DETAILED DESCRIPTION OF THE INVENTION
A paint supply apparatus according to an embodiment of the present invention will be described with reference to FIGS. 1 and 2. Reference numeral 10 denotes a paint pumping tank that pumps liquid paint from the paint discharge port 10a by air pressurization, and a paint circulation path 11 is connected between the paint discharge port 10a and the paint return port 10b. An air pump 13 is incorporated in series in the paint circulation path, and compressed air is selectively supplied from a common air pressure source to the paint pressure feed tank 10 by a three-way valve 15.
[0008]
Three-way valves 16 and 16a are incorporated before and after the air pump 13, and a bypass path 14 that bypasses the air pump 13 is connected as a parallel circuit. The coating gun 3 is connected as a branch circuit to the paint circulation path 11 on the downstream side of the three-way valve 16a, and the two-way valve 18 is incorporated in the paint circulation path 11 on the further downstream side. The paint circulation path 11 on the downstream side from the coating gun 3 is dedicated to the circulation of the paint, and the pipe diameter is set smaller than that on the upstream side. Correspondingly, the amount of paint delivered from the air pump 13 is reduced, and the pump pressure is lower than the original paint circulation system.
[0009]
The operation of the paint supply apparatus configured as described above is as follows. At the time of painting, as shown in FIG. 1 (the closed position of each valve is shown in black), the three-way valve 15 supplies compressed air to the paint pressure tank 10, and the three-way valves 16, 16a open the bias path 14. The two-way valve 18 is closed. As a result, the paint pressure-fed from the paint discharge port 10 a is supplied through the bypass passage 14 to the paint gun 3 whose attached valve is opened. Therefore, the paint is smoothly supplied without pulsation by the tank pressurization method, and high-quality painting is performed on the object to be coated.
[0010]
As shown in FIG. 2, the three-way valve 15 supplies compressed air instead of compressed air to the air pump 13 while the painting is stopped. The three-way valves 16 and 16a are switched to the side where the air pump 13 is opened. By opening, the paint is circulated to the paint return port 10b by the operation of the air pump 13. The paint does not need to be supplied to the coating gun 3 with the attached valve closed, and therefore, if a coating amount of paint that does not settle in the circulation path including the paint circulation path 11 is circulated with a small pipe diameter and a low pump pressure. Well, this also reduces the quality degradation associated with the paint circulation itself.
[0011]
The air pump 13 and the paint pressure-feed tank 10 may be supplied with compressed air from different air pressure sources. Further, the bypass path 14 can be directly connected to the paint circulation path 11 by eliminating one of the three-way valves 16 and 16a.
[0012]
【The invention's effect】
As described above, according to the present invention, the paint supply device that takes advantage of the paint circulation method and the tank pressurization method avoids the pulsation of the paint supply, stabilizes the discharge amount, and avoids the precipitation of the paint during the stop. By circulating the paint, it becomes possible to reduce the size of the circulation pump and the diameter of the circulation pipe, thereby reducing the equipment cost. Therefore, it is extremely effective as a paint supply apparatus that performs a small amount of painting that requires a stop time while the paint is stored.
[Brief description of the drawings]
FIG. 1 is a diagram showing a configuration of a paint supply apparatus according to an embodiment of the present invention.
FIG. 2 is a view for explaining a valve state during a circulation operation of the paint supply device.
FIG. 3 is a diagram showing a configuration of a conventional paint supply apparatus.
[Explanation of symbols]
3 Coating Gun 10 Paint Pressure Feed Tank 11 Paint Circulation Path 13 Air Pump 14 Bypass Path

Claims (1)

Connect a paint circulation path with an air pump that is activated when painting stops, between the paint discharge port and the paint return port of the paint pumping tank that pumps the paint by air pressure during painting.
A bypass path is connected to the air pump via a valve that opens to bypass the air pump during painting, a coating gun is connected to the paint circulation path on the downstream side, and the paint circulation path on the further downstream side A paint supply apparatus comprising a valve for opening the paint circulation path when painting is stopped.

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