JPH0832312B2 - Paint circulation equipment - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a paint circulator installed in a paint factory for automobiles or parts thereof, and more particularly, to a paint circulating device in which paint is fed from a paint tank. The present invention relates to a paint circulating device provided with a paint return line called a so-called third line in addition to the return paint circulation line.

(Prior Art) Conventionally, in an automobile painting plant, a paint circulation pipe is provided in the plant in order to supply paint to each of a large number of painting work positions in a painting line, and a branch from the circulation pipe is provided at each painting work position. There is provided equipment for branching each of the pipes so that each paint gun can be connected to the pipe, and for feeding paint to each paint gun through a circulation line and a branch pipe and returning it to the tank again (for example, Japanese Patent Publication No. 59-26350). (See the official gazette).

Recently, in order to prevent the paint from settling and fixing halfway inside the branch pipe from the circulation pipe to the painting gun,
It is common practice to provide a paint return line, which is a so-called third line, which connects with each branch pipe and collects the paint inside it into a paint tank.
-1100 gazette, see Jitsukai Sho 60-31377 gazette).

(Problems to be Solved by the Invention) In such a conventional automobile coating facility, when the paint in the paint tank becomes insufficient during operation, a required amount of new paint is supplied to the tank. The density and viscosity of the paint to be sent change. In addition, since the paint tank that is usually used is not a closed type from the viewpoint of workability, the solvent is always volatilized from the paint tank, so that the paint tends to gradually increase in concentration and viscosity. If the solvent is replenished in a timely manner, the concentration and viscosity of the paint will suddenly decrease at that point.

Thus, in the coating process, the concentration (viscosity) of the coating constantly changes and sometimes changes discontinuously. Therefore, even if a throttle valve for adjusting the amount of paint discharged from the coating gun is connected to a branch pipe branched from the paint circulation pipe line as shown in Japanese Patent Publication No. 59-26350. The discharge amount of the paint fluctuates due to the change in the viscosity of the paint, and it is difficult to keep the discharge amount at a predetermined constant value only by adjusting the valve.

Therefore, control means for maintaining the discharge amount of the paint at a constant value in accordance with changes in the concentration and viscosity of the paint is required, but such control means has not been available in the past.

As a discharge amount control device, as shown in Japanese Patent Publication No. 59-1106, there is a device that calculates conditions such as viscosity of paint by a central processing unit and controls the discharge amount of paint by its output signal. Already proposed. However, in this device, the temperature-viscosity curve data of the paint is programmed in the arithmetic processing device in advance, the viscosity condition of the paint is determined by inputting the environmental temperature value, and the paint discharge amount is controlled based on that. It was a discharge amount control means that could not cope with unexpected changes in paint concentration (viscosity) at all.

The present invention has been made in consideration of the above circumstances, and an object of the present invention is to reduce the concentration and viscosity of a paint, even if they change a little at all times and sometimes abruptly. It is an object of the present invention to provide a paint circulating device which can cope with the change well and can always maintain the discharge amount of the paint from the coating gun at a desired constant value.

(Means for Solving the Problem) The present inventor has focused on the fact that the concentration (viscosity) of the paint and the pressure of the paint flow have a substantially positive correlation, and the coating gun is controlled by control based on changes in the paint pressure. The present invention has been completed by finding that the discharge amount from the ink can be always maintained constant.

Therefore, the paint circulating apparatus of the present invention connects the paint circulating pipe to which the paint is fed from the paint tank and returns to the paint tank, and each connecting branch pipe branched from the circulating pipe and connected to the coating gun. In a paint circulation device having a paint return pipe for collecting the paint in a paint tank, a paint discharge amount regulator connected to each of the connection branch pipes, and a bypass pipe directly connecting the paint circulation pipe and the paint return pipe A metering pump and a paint pressure detecting device interposed in the passage, and a control mechanism for inputting a paint pressure signal from the detecting device and outputting a discharge amount signal set based on the paint pressure signal to each regulator. It is a feature.

Another paint circulating apparatus of the present invention is the paint circulating apparatus including the paint circulating conduit and the paint returning conduit, wherein a paint discharge amount regulator connected to each of the connecting branch pipes and the paint circulating pipe. Paint is fed from the paint tank and returned to the same tank through a pipe different from the pipe. A metering pump and paint pressure detection device interposed in the measurement paint circulation pipe, and a paint pressure signal is input from the detection device. However, a control mechanism for outputting a discharge amount signal set on the basis of this to each of the regulators is provided.

The paint circulation line and the paint return line may have basically the same configuration as the conventional one. For example, the paint circulation line includes a circulation pump, and the branch pipe branched from this includes a pressure reducing valve and a coating gun. And the paint return pipeline may be one in which a check valve or the like is provided in the return branch pipe communicating with each of the branch pipes.

The paint discharge amount regulator in the present invention may be any element capable of adjusting the amount of paint discharged from the coating gun,
For example, an air operated regulator is used. The regulator is installed in a branch pipe between the paint circulation line and the paint gun.

The bypass line is a line that directly connects the paint circulation line and the paint return line, and the metering pump and the paint pressure detection device are provided in this order. The metering pump keeps the flow rate of the paint flowing through the subsequent pipe line constant, and the device detects the pressure of the paint flowing at a constant amount and outputs it as an electric signal.
The paint pressure detection device in this case is composed of, for example, two pressure sensors, an orifice interposed between them, a capillary tube, etc., and measures the difference between the paint pressure in the paint circulation line and that in the paint return line. Anything that can be detected can be used.

The control mechanism inputs, for example, an electric signal of the detected paint pressure, and based on this, for example, the following equation (1) I = D (C ₂ / C ₁ ) ·· (1) [wherein, I is It represents the magnitude of the electric signal of the discharge amount (current value), C ₁ represents the initial value of the pressure difference detected by the two pressure sensors (before coating), and C ₂ is the pressure detected by the two pressure sensors. It represents the elapsed value of the difference (during coating), and D represents the proportional coefficient or the magnitude of the electric signal of the discharge amount before coating. ], The control circuit that determines the electric signal of the amount of paint to be discharged and outputs it, and the electric / pneumatic converter that converts the output electric signal into a pneumatic pressure signal and sends this to the above air operated regulator. Composed.

The measuring paint environmental conduit used in the second invention of the present invention is
A line separate from the paint circulation line that allows the paint to leave the paint tank and back again. A metering pump and a paint pressure detecting device are also installed in this line in this order. The metering pump may have the same configuration as described above, and the paint pressure detecting device may be, for example, one pressure sensor and an orifice or the like, and may detect the pressure itself of the paint flowing through the circulation pipe line.

(Operation) In the paint circulation device of the present invention, the flow of the paint flowing into the bypass pipe or the measurement circulation pipe is first made constant by a metering pump, and in this state, the pressure of the paint is detected by a pressure sensor or the like. Then, the control mechanism sets the amount of paint to be discharged from the coating gun based on this pressure signal, and sends the discharge amount signal to the discharge amount regulator installed in the branch pipe communicating with the paint circulation pipe line. Eggplant

That is, the apparatus of the present invention immediately recognizes the change in the concentration or viscosity of the paint as the fluctuation value of the paint pressure, accurately sets the paint amount to be discharged from this pressure fluctuation value, and adjusts the discharge amount regulator based on this. By controlling the operation, the amount of paint discharged from the coating gun can be adjusted to the paint concentration (viscosity).
It can always be kept constant without being affected by changes in.

(Example) Hereinafter, the Example of this invention is described with reference to drawings.

Embodiment 1 As shown in FIG. 1, the paint circulating apparatus of the embodiment is installed in a paint booth of an automobile, and the paint tank 1 around the booth and the paint piped along the booth wall to the entire booth. A circulation line 2 and a paint return line 3 are provided.

The paint tank 1 constantly mixes paints by a propeller mixer 23 to prevent the paints from settling.

The paint circulation pipe line 2 branches the connection branch pipe 4 at each painting work site in the booth and can be connected to the painting gun 9. Each branch pipe 4 is provided with an air-actuated regulator 7 for adjusting the amount of paint discharged from the coating gun 9.

The paint return line 3 has a switching terminal 8 in each connection branch pipe 4.
It has a return branch pipe 5 (including a check valve, etc.) that communicates with each other, and a main pipe that connects them is connected to the paint tank 1.

Therefore, by operating the circulation pump 6, the paint is fed from the paint tank 1 to the paint circulation pipe line 2 and circulates through the pipe line 2 and then returns to the tank 1 again (direction of arrow p). The paint that has flowed into the branch pipe 4 is the painting gun 9
However, when not painting, it enters the return branch pipe 5 from the switching terminal 8 and is collected as it is in the paint tank 1 through the paint return pipe line 3 (arrow q direction).

In the embodiment, as shown in FIG. 2, the circulation line 2 and the return line 3 are directly connected to each other by the bypass line 10 immediately before entering the coating booth, and the pressure reducing valve 15, the fixed amount is fixed to the line 10. A pump 11 and a paint pressure detection device 18 are provided in this order.

The detection device 18 is composed of two pressure sensors 12, 13 and an orifice (or capillary tube) 14 provided between them.

Therefore, the paint (in the direction of arrow r) flowing in from the circulation line 2 is made to flow in a constant amount by the metering pump 11, and the pressure of the subsequent flow is detected by the sensors 12 and 13. a,
b shows the electric signal of the detected pressure.

Further, the apparatus of the embodiment comprises a control circuit 16 and an electric / pneumatic pressure converter 17, as shown in FIG. Control circuit
Reference numeral 16 is a control electric signal c which receives the electric signals a and b of the paint pressure from the above-mentioned sensor, sets the amount of paint to be discharged from the coating gun 9 based on the above-mentioned formula (1), and the like.
Is output and sent to the converter 17. The converter 17 converts the electric signal c into a corresponding air pressure signal d and sends it to each air operated regulator 7 (FIG. 1). Therefore, the operation of the regulator 7 is adjusted according to the signal level from the control circuit 16, and the amount of paint discharged from the coating gun 9 is controlled.

The apparatus of Example 1 was able to maintain the desired discharge amount of the coating material even when the coating material and the solvent were replenished and the concentration and the viscosity of the coating material were changed during the coating operation.

Example 2 The paint circulating apparatus of this example is as shown in FIG.
Instead of the bypass pipeline and its interposed (connecting) component, a measurement paint circulation pipeline 22 different from the paint circulation pipeline 2 is provided. The measurement circulation pipe line 22 comprises a metering pump 11 and a paint pressure detection device 21 in this order. The detection device 21 includes a pressure sensor 19 and an orifice (capillary tube) 20. Therefore, by the operation of the pump 11, the paint flows through the circulation pipe line 22 in a constant amount (direction of arrow s), and the pressure of the paint flowing therethrough is detected by the sensor 19. e indicates an electric signal of the detected pressure, which is sent to the control circuit 16. The control circuit 16 sets the amount of paint to be discharged from the coating gun according to a predetermined calculation on the basis of the input signal e, and outputs a control electric signal c indicating the amount of electric power.
Send to the air pressure converter 17. Other configurations, operations, etc. are similar to those of the first embodiment.

Even in the apparatus of Example 2, the amount of coating material discharged from the coating gun could be maintained at a desired fixed amount even if the concentration or viscosity of the coating material changed.

Although the above embodiment has been described with respect to the case of using a manual coating gun, it goes without saying that the present invention can be similarly applied to the case of using an automatic coating gun. In this case, an automatic three-way valve is used instead of the switching terminal 8.

(Effects of the Invention) As described above, in the paint circulating apparatus of the present invention, the concentration and the viscosity of the paint always change a little in the course of painting, and sometimes even when the paint or solvent is replenished rapidly. The effect of responding well to these changes and maintaining the desired discharge amount of the paint from the coating gun at all times is obtained.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram showing a paint circulating apparatus according to Embodiment 1 of the present invention, FIG. 2 is an enlarged view showing a portion of a frame A in FIG. 1, and FIG. 3 is a control mechanism of the apparatus shown in FIG. FIG. 4 is a schematic configuration diagram showing a paint circulating device of a second embodiment. In the figure, 1 ... Paint tank 2 ... Paint circulation pipe 3 ... Paint return pipe 4 ... Connection branch pipe 5 ... Return branch pipe 7 ... Air-operated regulator 9 ... Painting gun 10 ... Bypass Pipe line 11 …… Metering pump 12, 13, 19 …… Pressure sensor 16 …… Control circuit 17 …… Electric / pneumatic pressure converter 18, 21 …… Paint pressure detection device 22 …… Measuring paint circulation line a, b , E ... Pressure detection signal c ... Control electric signal d ... Control air signal p ... Paint circulation flow q ... Paint return flow r ... Bypass flow s ... Measurement paint circulation flow

Claims (2)

[Claims] 1. A paint circulating pipe line to which paint is fed from a paint tank and returned to the same tank, and each connecting branch pipe branched from the circulating pipe line and connected to a coating gun to collect the paint into the paint tank. In a paint circulating device having a paint return pipe, a paint discharge amount regulator connected to each of the connecting branch pipes and a bypass pipe directly connecting the paint circulating pipe and the paint return pipe. A paint circulating device comprising a metering pump and a paint pressure detection device, and a control mechanism for inputting a paint pressure signal from the detection device and outputting a discharge amount signal set on the basis of the paint pressure signal to each of the regulators. 2. A paint circulating pipe line to which the paint is fed from the paint tank and returned to the same tank, and each connecting branch pipe branched from the circulating pipe line and connected to a painting gun, to collect the paint into the paint tank. In the paint circulation device having a paint return pipe for controlling the paint, the paint is supplied from the paint tank through a paint discharge amount regulator connected to each of the connection branch pipes and a pipe different from the paint circulation pipe. A metering pump and a paint pressure detection device interposed in the measurement paint circulation pipe that was sent and returned to the same tank, and a paint pressure signal was input from this detection device, and the discharge amount signal set based on this was input to each regulator. A paint circulating device comprising a control mechanism for outputting.