JP2858048B2 - Paint supply control method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for controlling the supply of paint having thixotropic properties.

[0002]

2. Description of the Related Art Paint supply systems are roughly classified into a dead end system, a loop system and a third line system. The dead-end method is a method in which a paint is supplied from a paint tank to a supply pipe whose final end is closed by a pump, and a branch pipe is branched from a necessary portion of the supply pipe to connect a coating head. The loop type is a method in which the end of the supply pipe is returned to the paint tank, paint is constantly circulated in the supply pipe, and the paint is supplied to the application head through a branch pipe branched from a necessary portion of the pipe. In addition, the third line type means that a coating head is branched and connected to an intermediate portion of the branch pipe in the loop type, a third pipe is connected to the ends of the branch pipes and returned to the paint tank, and paint is always applied to the branch pipe. Is circulated. The third-line type has a high facility cost and it is difficult to adjust the pressure of the third pipe. Therefore, a loop type is generally used for a coating material in which components in the coating material do not precipitate.

[0003]

By the way, in the case of a coating material in which there is no possibility of sedimentation of the components in the coating material, in the case of a fuel having a so-called thixotropic property in which the viscosity is reduced due to the continuation of the flow, the coating operation is interrupted by using a loop type fuel. Since the paint sometimes stays in the branch pipe and the viscosity of the paint increases, a required discharge amount cannot be obtained when the coating operation is restarted, and the film thickness of the portion to be coated becomes thin. For this reason, in the case of paints having thixotropic properties, it is common to adopt a supply method that allows the paint to circulate in the third-line system or even in the connection circuit between the branch pipe and the application head, which increases equipment costs. Has been invited. SUMMARY OF THE INVENTION In view of the above, an object of the present invention is to provide a paint supply control method capable of applying a thixotropic paint without any support even in a loop supply method.

[0004]

In order to achieve the above object,
In the present invention, when the coating operation is interrupted until the viscosity of the coating material is increased and then the coating operation is restarted, the discharge pressure of the coating material is set to be larger than the normal discharge pressure for a certain period of time.

[0005]

When the application operation is interrupted, even if the viscosity of the paint increases due to thixotropy, a decrease in the discharge amount can be prevented by increasing the discharge pressure when the application operation is restarted. After a lapse of a certain time after the restart, the viscosity of the paint decreases to a normal value. Therefore, the discharge pressure is increased only for a certain time after the restart.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to FIG. 1, reference numeral 1 designates a loop-type supply pipe coming out of a paint tank (not shown) and returning to the tank. The paint was supplied. Between the branch pipe 2 and the coating head 3,
A regulator 4, a color changing valve 5, an air operated regulator 6, and a trigger valve 7 are interposed in order from the upstream side. 1 through each branch pipe 2, and the air operation regulator 6 is controlled by a controller 8 having a built-in timer, so that the discharge pressure of the paint can be increased or decreased.

FIG. 3 shows the change in viscosity of a thixotropic paint manufactured by Kansai Paint Co., Ltd. when the flow stops. With this paint, the viscosity of the paint in the branch pipe 2 increases from 600 poise to about 1000 poise by suspending the coating operation for 5 minutes,
In order to obtain a required discharge amount when the coating operation is restarted after 5 minutes, the discharge pressure needs to be about 10 to 20% higher than the normal value. Thus, a master controller (not shown) calculates a pressure rise value corresponding to the interruption time of the coating operation, and controls the air operated regulator 6 via the controller 8 when the coating operation is resumed, to calculate the discharge pressure calculated by the controller 8. To increase for a certain period of time. The viscosity of the paint returns to a normal value in about 5 to 10 seconds, depending on the length of the branch pipe 2, and the above-mentioned fixed time is set in accordance with this time.

[0010] FIG. 2 is a view similar to the above embodiment, in which an intermediate portion of a branch pipe 2 branched from a loop type supply pipe 1 is applied via a regulator 4, a color changing valve 5, an air operated regulator 6, and a trigger valve 7. Connect head 3 and branch 2
A third-line type embodiment in which a third pipe 9 returning to the paint tank is connected to the end of the pipe and the paint is constantly circulated also in the branch pipe 2 is shown. As a result, the viscosity increases due to the stagnation of the paint in the connecting pipe 10, and the discharge pressure is increased for a certain time when the application operation is resumed after the interruption.

[0009]

As is apparent from the above description, according to the present invention, even if the viscosity of the paint increases due to the thixotropic property due to the stoppage of the flow of the paint when the coating operation is interrupted, the coating operation is restarted. By increasing the discharge pressure for a certain period of time, the required amount of paint can be discharged from the beginning of resumption, and the application of thixotropy paint can be performed without hindrance using the loop-type paint supply equipment. Even when equipment is used, there is an effect that the thixotropic paint can be accurately applied without being adversely affected by the stagnation of the paint in the connecting pipe branched from the branch pipe.

[Brief description of the drawings]

FIG. 1 is a circuit diagram of a main part of a loop-type paint supply facility used for carrying out the method of the present invention.

FIG. 2 is a circuit diagram of a main part of a third-line type paint supply facility used for carrying out the present invention.

FIG. 3 is a graph showing a change characteristic of a viscosity of a paint.

[Explanation of symbols]

1 supply pipe, 2 branch pipe, 3 coating head,
6 air operated regulator, 8 controller

Claims (1)

(57) [Claims] 1. A method for controlling the supply of paint having thixotropy, comprising: interrupting the coating operation until the viscosity of the coating material increases, and then restarting the coating operation. A paint supply control method, characterized in that the paint supply is made larger.