JPH0832314B2 - 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 a facility for branching each of the pipes so that each paint gun can be connected to the pipe, and for feeding the 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. (See the official gazette).

Recently, in order to prevent the paint from settling and semi-solidifying 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, and 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 paid attention to the fact that the viscosity of the paint and the flow rate of the paint have a substantially negative correlation under the condition that a constant feed pressure is applied to the paint, The present invention has been completed by finding that the discharge amount from the coating gun can be always maintained constant by the control based on the change of the paint flow rate below.

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 paint flow rate regulator and a paint flow rate detection device interposed in the path, and a control for inputting a paint flow rate signal from the detection device and outputting a flow rate signal and a discharge amount signal set on the basis of the paint flow rate signal and the discharge amount regulator And a mechanism.

The paint circulation line and the paint return line may have a configuration similar to the conventional one basically designed to feed the paint under a constant pressure condition, for example, the paint circulation line includes a circulation pump. The branch pipe that branches further may be equipped with a pressure reducing valve and equipped with a switching terminal for the coating gun, and the paint return line may have a check valve or the like in the return branch pipe that communicates with each branch pipe. You can wear a costume.

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 pipeline is a pipeline that directly connects the paint circulation pipeline and the paint return pipeline, and a paint flow regulator and a paint flow detection device are provided in this order. The flow rate regulator may be any element that receives a flow rate signal from the control mechanism described below and acts to make the flow rate of the paint flowing through the bypass pipe line thereafter constant, for example, an air actuated regulator may be used. Further, the flow rate detecting device may be any element that detects the flow rate of the paint flowing in the bypass pipe and outputs it as an electric signal, and for example, a vibration type flow meter may be used.

The control mechanism inputs, for example, an electric signal of the detected paint flow rate, 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 paint flow rate (before coating) detected by, for example, a vibration type flow meter, and C ₂ is detected by, for example, a vibration type flow meter. Represents the elapsed value of the paint flow rate (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 output electric signal is converted into an air pressure signal, and this is used as a flow rate signal, and the air actuated regulator in the above bypass pipeline. And an electric / pneumatic converter which sends as a discharge signal to each of the air-operated regulators in the connecting branch.

(Operation) The paint circulation device of the present invention detects the flow rate of the paint flowing into the bypass pipe that directly connects the paint circulation pipe and the paint return pipe with a vibration type flow meter or the like, and the control mechanism detects this flow signal. Based on this, set the amount of paint to be discharged from the coating gun, and send the discharge amount signal to the discharge amount regulator of the branch pipe that is separated from the paint circulation pipe. It operates to control.

That is, the apparatus of the present invention immediately recognizes the change in the viscosity of the paint under a constant feed pressure as the fluctuation value of the paint flow rate, and accurately sets the paint quantity to be discharged from this fluctuation value of the flow rate. This is to control the adjusting operation of the discharge amount regulator based on the base, and therefore, the discharge amount of the paint from the coating gun can be always kept constant without being influenced by the change of the viscosity of the paint.

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

As shown in FIG. 1, the paint circulating apparatus of the embodiment is installed in a paint booth of an automobile, and a paint tank 1 around the booth and a paint circulating pipe lined along the booth wall to the entire booth. 2 and a paint return line 3.

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 and the air are connected to the line 10. An operation type regulator 12 and a vibration type flow meter 11 are provided in this order.

Therefore, the flow rate of the paint (in the direction of arrow r) flowing in from the circulation line 2 under a constant feed pressure condition is detected by the vibration type flow meter 11. a shows an electric signal of the detected flow rate.

Further, the apparatus of the embodiment comprises a control circuit 16 and an electric / pneumatic pressure converter 17, as shown in FIG. Control circuit
An electric signal a representing the paint flow rate from the flow meter 11 is inputted to the numeral 16, and the quantity of paint to be discharged from the painting gun 9 is set based on the above-mentioned formula (1). Is output and sent to the converter 17. The converter 17 converts the electric signal b into corresponding pneumatic pressure signals c and d, sends the flow rate signal of the signal c to the air actuated regulator 12 of the bypass line 10 (FIG. 2), and discharges the signal d. A signal is sent to each air-operated regulator 7 of the branch pipe 4 (Fig. 1). Therefore,
The operation of the regulator 7 is adjusted according to the signal level from the control circuit 16 to control the amount of paint discharged from the coating gun 9 and the flow rate of paint in the bypass line 10.

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 viscosity of the coating material were changed during the coating operation.

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. Further, in the embodiment, the case of using the air actuated regulator has been described, but it goes without saying that an electric actuated regulator may be applied instead.

(Effects of the Invention) As described above, in the coating material circulation device of the present invention, the viscosity (concentration) of the coating material always changes slightly during the coating process,
Even if it suddenly fluctuates due to replenishment of paint or solvent, it is possible to effectively cope with such changes and maintain the desired discharge amount of the paint from the coating gun.

[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. 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 …… Vibration type flow meter 12 …… Air actuated regulator 16 …… Control circuit 17 …… Electric / pneumatic converter a …… Pressure detection signal b …… Control electric signal c, d …… Control air signal p …… Paint circulation flow q …… Paint return flow r …… Bypass flow

Claims (1)

[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 flow rate regulator and a paint flow rate detection device, and a control mechanism that inputs a paint flow rate signal from the detection device and outputs a flow rate signal and a discharge amount signal set based on the paint flow rate signal to the flow rate regulator and the discharge amount regulator. Paint circulating equipment.