JPH0824858B2 - Quantitative supply method of residual paint in paint hose - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Use) The present invention discharges residual paint in a paint hose from a spray gun at a constant flow rate by air pressure when changing the color of paint discharged from a spray gun. The present invention relates to a method for quantitatively supplying residual paint in a paint hose.

(Prior Art) When an automobile body is used as an object to be overcoated, the color of the paint to be applied may be changed depending on the object. For this purpose, a color change valve is formed by a number of valve members to which paint supply hoses are connected, and a spray gun is attached to the discharge end of this valve via the paint hose. The paint of the above can be discharged from the spray gun. When changing colors, remove the paint used for the previous painting because it remains mainly in the paint hose, including the color change valve and spray gun, in these flow paths. , It is necessary to wash the part of the flow path where the previous color paint is attached.

If all of the above residual paint is discarded to the outside, the loss of the paint will increase, so this residual paint should be used for application of the object to be coated. Conventionally, the paint supply of a predetermined color from the color change valve After stopping the operation, the residual paint is extruded by using air having a constant pressure corresponding to the discharge amount of the paint so that the paint can be effectively used.

FIG. 6 is a view showing a conventional constant amount residual paint supply device in a paint hose. The color change valve 1 is composed of a number of valve members, each of which is operated by compressed air from an air pressure path indicated by a broken line. ing. Further, paint supply hoses 2 and 3 are connected to a part of these valve members.
Actually, paint supply hoses corresponding to the number of colors to be applied to the vehicle to be coated are connected to the color change valve 1, but only two are shown in FIG. Each paint supply hose 2, 3 is a pump 4,
Outward-side flow paths 2a and 3a and return-side flow path connected to the discharge side of No. 5
2b and 3b, and the return passages 2b and 3b are connected to paint sources 8 and 9 by hoses 6 and 7, respectively.
It should be noted that one of the two paint supply hoses is for supplying metallic paint, and the gear pump 4 operates when the clutch 10 discharges the paint from the paint supply hose 2. There is. And the symbols a and 7a
Indicates regulators, respectively.

A paint hose 12 having a spray gun 11 is connected to the color change valve 1 so that paint from a predetermined one of many paint sources is discharged from the spray gun 11. The on / off of the discharge is performed by an opening / closing valve (on / off valve) 13 provided in the paint hose 12. When changing the color of the paint discharged from the spray gun 11, it is necessary to remove the paint remaining between the color change valve 1 and the spray gun 11 and clean the inside of these channels. For this purpose, a hose 14 for cleaning is connected to the color change valve 1.
An upstream side of the two-way valve 15 is branched into a thinner supply passage 14a for supplying thinner as a solvent and an air pressure passage 14b for supplying compressed air. In addition, each supply path 14a, 1
4b is provided with regulators 16 and 17 for pressure adjustment. Reference numeral 18 is a solenoid valve that opens and closes the pneumatic passage 14b, and the two-way valve 15 is operated by a pneumatic passage 20 having a solenoid valve 19. Further, the opening / closing valve 13 is also operated by the pneumatic passage 22 having the solenoid valve 21.

If all of the residual paint is discarded, the paint cannot be effectively used. Therefore, when the color is changed, the residual paint is also used to apply it to the object to be coated. For this reason, as shown in FIG. 6, a pneumatic passage 20 is connected to the color change valve 1 so that residual paint is discharged by compressed air from the pneumatic passage 20.

(Problems to be Solved by the Invention) In the sixth prior art, two air pressure passages 25 are provided in accordance with the number of the two paint supply hoses shown in the drawing, and each air passage 25 is provided. The pressure passage 25 is provided with an electromagnetic valve 26 for opening and closing the inside of the passage and an air regulator 27 for adjusting the pressure of air in the passage. Since a plurality of air regulators 27 are provided in this way, the characteristics such as viscosity are different depending on the residual paint, and thus each color or a plurality of colors are grouped as one group.
This is to change the air pressure for discharging the residual paint.

When the color is changed using such a coating device, in order to apply the residual paint to the object to be coated, select the air pressure corresponding to the paint color of the residual paint and spray the residual paint with that pressure. I am trying to discharge from 11. However, such a conventional residual paint supply method has a problem that the amount of residual paint discharged from the spray gun 11 increases as the residual paint decreases. Then, the change in the discharge amount is affected by various influences such as the temperature, and is changed for each painting work.

The present invention has been made in view of the above-mentioned problems of the prior art, and an object of the present invention is to make it possible to discharge a residual paint from a spray gun at a constant discharge amount.

(Means for Solving Problems) In order to achieve the above object, the present invention provides a spray gun through a paint hose at the discharge end of a color change valve including a plurality of valve members to which paint supply hoses are connected. In the fixed amount supply method, in which the paint remaining in the paint hose is discharged from the spray gun by the compressed air from the pneumatic flow path connected to the color change valve, the paint provided in the paint hose The signal from the pressure sensor that detects the pressure in the hose is sent to the control means, and the signal from the control means is sent to the pressure control valve provided in the pneumatic passage to keep the pressure in the paint hose constant. This is a method for providing and supplying the residual paint in the paint hose.

(Function) When the paint remaining between the color change valve and the spray gun is used for painting, if the amount of the residual paint changes with the discharge of the paint from the spray gun, a constant air pressure is applied. If the residual paint is pressurized, the discharge amount will change, but in the present invention, the pressure in the coating hose is detected by the pressure sensor, and the air in the pneumatic passage is adjusted so that this pressure becomes constant. The pressure will change. As a result, the painting work using the residual paint is performed with the same painting quality as the normal painting work, and the effective use of the residual paint can be achieved.

(Example) Hereinafter, it demonstrates in detail based on the Example of this invention shown in figure.

FIG. 1 is a diagram showing a constant quantity supply device by embodying the constant quantity supply method of the residual paint in the paint hose of the present invention, and the parts common to the parts shown in the conventional example are designated by the same reference numerals. is there.

In FIG. 1, two paint supply hoses 2 and 3 are connected to the color change valve 1, and the paints from the paint sources 8 and 9 are respectively colored through the paint supply hoses 2 and 3. Paint hose 12 connected to change valve 1
Will be discharged from the spray gun 11. Hose 6 connected to each paint supply hose 2, 3,
7 is a regulator 6a, 7a for adjusting the paint pressure.
Is provided.

A pressure sensor 30 is provided between the on-off valve 13 and the spray gun 11 of the paint hose 12 to detect the pressure in the paint hose 12, and the signal from the pressure sensor 30 is a second signal. It is sent to the control means 31 shown in the figure. On the other hand, a pneumatic passage 31 is connected to the color change valve 1 in order to apply the residual paint when the residual paint is applied to the object to be coated. An air regulator 34 for adjusting the air pressure from an air pressure source 33 is provided in the pneumatic pressure passage 32, and an electropneumatic proportional valve 35 as a pressure control valve is provided in the pneumatic pressure passage 32 by a signal from the control means 31. It is provided.
Incidentally, reference numeral 36 in FIG. 1 denotes an electromagnetic valve. Further, in the portion of the color change valve 1 to which the pneumatic passage 32 is connected, a pneumatic passage 29 having an electromagnetic valve 28 is connected to operate the valve member.

The control means 31 has an A / D converter 37 that converts an analog signal from the pressure sensor 30 into a digital signal, and the signal from the pressure sensor 30 is sent to a CPU (computer) 38. The control means 31 is further provided with condition input means 39 for inputting conditions such as the amount of paint discharged and the spray gun 11 on / off, and pressure signal data from the ROM storing the arithmetic expressions and the pressure sensor 30. A storage means 40 including a RAM for storing is provided.

The digital signal output in parallel from the CPU 38 is converted into a pressure signal by the D / A converter 41 and sent to the electropneumatic proportional valve 35. The operation of the electropneumatic proportional valve 35 controls the pressure of air in the pneumatic passage 32. In FIG. 1, reference numeral A indicates the inside of a coating booth, in which the automobile body as an object to be coated is conveyed by a conveyor. The discharge of the paint from the spray gun 11 onto the object to be coated is performed by an automatic machine such as a welding robot or a reciprocator. The symbol B indicates the booth side,
The symbol C indicates outside the booth.

Next, the control procedure in the quantitative supply method of the present invention will be described with reference to the flowchart shown in FIG.

When the amount of discharge or data for selecting a specific color to be applied is input, the gear pump operates and the discharge of paint by the gear pump is started.

For example, spray the paint from the paint supply hose 2
When discharging from 11, the gear pump 4 is operated and the paint passing through the color change valve 1 is sent to the spray gun 11 by the paint hose 12. Spray gun in this way
Pressure sensor 30 with paint applied from 11
The pressure data P0 in the paint hose 12 detected by is read into the RAM in the storage means 40. When the coating of one object is approaching the end, the color change valve 1 is operated to stop the supply of the paint from the paint supply hose 2 and the residual paint by air is utilized by using the air pressure passing through the pneumatic passage 32. Apply. When the application of the residual paint using this compressed air is started, the pressure of the paint in the paint hose 12 is sampled by the pressure sensor 30. The sampling pressure P is compared with the pressure data P0 in the CPU 38. If the sampling pressure P is higher than the pressure data P0,
A signal to decrease the output is sent from the CPU 38 to the electropneumatic proportional valve 35, and conversely, if the sampling pressure is lower, a signal to increase the output is sent to the electropneumatic proportional valve 35. In this way, the paint hose detected by the pressure sensor 30
By feeding back the pressure in 12 to the electropneumatic proportional valve 35 as a pressure control valve, the pressure of the extrusion air is controlled, the pressure in the coating hose 12 is kept constant, and the amount of residual paint discharged is kept constant. Will be retained.

The above-described sampling of the pressure P and the comparison with the pressure P0 are performed until the remaining amount of the residual paint reaches a predetermined residual amount or 0, and is continued until the discharging operation is completed.

In this way, after the residual paint is applied to the object to be coated, the thinner is supplied from the cleaning hose 14,
Next, compressed air is supplied to clean the space between the color change valve 1 and the spray gun 11.

FIG. 5 (A) is a graph showing the outlet pressure in the paint hose 12 and the discharge amount of the paint from the spray gun 11 when the heating air pressure is constant as in the conventional case. B) is the pneumatic flow path 32 in the quantitative supply method of the present invention.
3 is a graph showing the pressure of air extruded from inside, the pressure on the outlet side in the paint hose 12, and the amount of paint discharged from the spray gun 11. In the illustrated embodiment of the present invention, the feedback cycle was 0.36 seconds, once.

FIG. 4 is a view showing an apparatus embodying a method for quantitatively supplying residual paint in a paint hose according to another embodiment of the present invention,
In this case, the gear pumps 4 and 5 in the above-described embodiment are not used, and the paint hose 12 is provided with an air-operated air-operated regulator 40.
The paint flow rate is controlled by. The paint supply hose 3 in this case is provided with a pressurizing cylinder 41, and the paint is pressurized by the reciprocating movement of the cylinder therein. The pressurizing cylinder 41 has a pneumatic passage 42.
A pressure booster 43 that is operated by compressed air from the
The paint is sequentially supplied to the color change valve 1 by the operation of. Other configurations are similar to those of the above-described embodiment, and common members are denoted by the same reference numerals. In FIG. 4, reference numeral 45 indicates a regulator, and reference numeral 46 indicates a solenoid valve. The three-way valve 44 is operated by compressed air from the pneumatic passage 48 having a solenoid valve, and
The regulator 40 is also operated by compressed air from the pneumatic passage 50 having a solenoid valve 49. Furthermore, the fourth
In the figure, reference numeral 51 indicates a micromotion flowmeter.
Also in this case, the residual paint can be discharged from the spray gun 11 at a constant discharge amount as in the case of the above-described embodiment.

(Effects of the Invention) According to the present invention as described above, a signal from a pressure sensor provided in a paint hose for detecting the pressure in the paint hose is sent to the control means, and the signal from the control means is sent to the pneumatic passage. The pressure in the paint hose was kept constant by sending it to the pressure control valve installed in the paint hose, so after painting work on the object with paint of one color is completed, paint of another color is applied. When the Seo is performed, the supply of the paint from the paint supply hose can be stopped, and the paint remaining from the color change valve to the spray gun can be discharged from the spray gun at a constant discharge amount. As a result, it is possible to perform the coating work on the object with a good quality by the residual paint.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing a coating apparatus embodying the method for quantitatively supplying residual paint in a paint hose of the present invention, FIG. 2 is a circuit diagram showing a control means of the present invention, and FIG. 3 is a flow chart showing a control process. FIG. 4 is a schematic view showing a coating apparatus which embodies a quantitative supply method according to another embodiment of the present invention, and FIGS. 5 (A) and (B) compare experimental data of the present invention with a conventional supply method. FIG. 6 is a schematic diagram showing a conventional residual paint supply method. 1 ... Color change valve, 2, 3 ... Paint supply hose, 11 ... Spray gun, 12 ... Paint hose, 30 ... Pressure sensor, 31 ... Control means, 32 ... Pneumatic flow passage, 35 ...
Pressure control valve (electropneumatic proportional valve).

Claims (1)

[Claims] 1. A spray gun is connected via a paint hose to the discharge end of a color change valve, which is composed of a number of valve members to which paint supply hoses are respectively connected, and an air pressure passage connected to the color change valve is connected. In the quantitative supply method in which the paint remaining in the paint hose by compressed air is discharged from the spray gun, a signal from a pressure sensor provided in the paint hose for detecting the pressure in the paint hose is used as control means. A constant amount of residual paint in the paint hose characterized in that the pressure in the paint hose is kept constant by sending a signal from the control means to a pressure control valve provided in the pneumatic passage. Method.