JPH0626694B2 - Automatic spray coating method - Google Patents

Description

TECHNICAL FIELD The present invention relates to an automatic spray coating method for automobile bodies and the like.

"Prior art" In automatic spray coating of automobile bodies, conventionally, control of coating conditions such as paint discharge rate, shaping air pressure, atomizing head rotation speed in coating gun, spray distance, etc., according to the shape of the object to be coated. By doing so, it is possible to prevent the coating film from dripping or sinking and to make the coating film thickness uniform.

However, when painting a complicated shape part with a paint that can appropriately paint a gentle shape part,
If the amount of coating material discharged is reduced and the number of revolutions of the atomizing head is increased to reduce the coating dripping, the concentration of the non-volatile matter deposited during coating is increased and the flowability of the coating material is deteriorated. Therefore, there is a problem in that the smoothness of the painted skin is poor. As the shape of the article to be coated becomes more complicated, this tendency becomes more prominent, and there is a problem that the variation in smoothness increases depending on the shape.

"Problems to be Solved by the Invention" The present invention has been made to solve the above problems.
An object of the present invention is to provide an automatic spray coating method that enhances the smoothness of painted skin and reduces variations in smoothness.

"Means for Solving Problems" In order to achieve the above object, the automatic spray coating method of the present invention increases the paint viscosity in a complicated shape part of the object to be coated, and the paint viscosity in a gently-shaped thin plate. In order to lower the temperature, the amount of the diluent solvent to be mixed with the paint is controlled in the paint mixing valve that switches the discharge and circulation of the paint.

[Operation and Effect of Invention] According to the automatic spray coating method having the above-mentioned configuration, the diluent solvent is added to the paint and mixed in the paint mixing valve in which the discharge and circulation of the paint can be controlled to be switched. The amount is controlled according to the shape part of the object to be coated. Therefore, at the same time as the operation of switching the discharge and circulation of the paint in the paint mixing valve, the addition amount of the diluting solvent mixed with the paint is adjusted or the addition and non-addition of the diluent is switched, so that the complicated shape part In this case, the paint viscosity can be increased, and the paint viscosity can be decreased in areas with gentle shapes to improve the smoothness of the coating surface and reduce variations, and the structure of the device is simple, making automatic spray coating easy. There is an effect that can be done.

[Example] An example of the automatic spray coating method of the present invention will be described with reference to Figs. 1 and 2.

In FIG. 1, an external input 101 is an object to be coated detection signal, an object to be coated type determination signal, a coating color signal, a conveyor synchronization signal, etc., which is input by an input device such as a limit switch, an operation switch or a sensor. External output 10
2 is an electric signal, a pneumatic signal, etc. output by output devices, such as a solenoid valve, a relay, and a display.

A readable / writable random memory is used as the memory substrate 103, and stores coating conditions such as a paint discharge amount and shaping air pressure. Central processing unit (hereinafter referred to as CPU)
104 executes a predetermined program to read out the stored contents of the memory substrate 103, and at the same time the external input 101
The signal is transferred to the output substrate 106, the ejection amount control substrate 107, etc. through the bus line 130. The input board 105 and the output board 106 transmit information between stages and output setting data when the system has multiple stages.

The discharge amount control board 107 and the digital / analog conversion board 108 are directly or by the output board 10 by the CPU 104.
The digital value data designated via 6 is converted into an analog value voltage or current.

The frequency converter 109 converts the voltage or current output by the discharge rate control substrate 107 into electric power having a frequency according to the value. The electropneumatic converter 110 converts the voltage or current received from the digital / analog conversion board 108 into air pressure according to the value.

A gear pump driving motor 111 is connected to the output side of the frequency converter 109, and the gear pump 112 is rotationally driven by the motor 111, and the discharge amount of the paint is determined in proportion to the rotation speed.

The air operate paint regulator 113 determines the addition amount of the diluent solvent according to the air pressure of the electropneumatic converter 110.

The mixing valve 114 for paint switches the discharge and circulation of the paint from the paint tank 119 by the structure shown in FIG.
Switch addition and non-addition of diluent solvent from 20. The paint discharged from the paint mixing valve 114 is sprayed from the paint gun 116 through the trigger / dump valve 115.
The trigger dump valve 115 is provided in the painting gun 116. When the automobile body 121 is painted, the trigger valve is opened to send the paint to the tip of the painting gun 116, and when the color is changed or washed, the dump valve is opened to drain the liquid. The paint is discharged to the tank 118. The coating gun 116 is of a rotary atomizing electrostatic system.

The graphic terminal 117 is equipped with a cathode ray tube and a keyboard and is used when setting and changing the coating conditions. Data input from the keyboard of the graphic terminal 117 is stored in the storage element inside the memory substrate 103.

As shown in FIG. 2, the above-mentioned paint mixing valve 114 has a valve body 7 provided with a pilot air inlet 1, a paint inlet 2, a paint return port 3 and a paint outlet 6. A paint needle valve 8 is arranged in the flow path 4 reaching the return port 3.

A diluent solvent inlet 9 into which the diluent solvent 10 flows into the valve body 7.
And a mixing chamber 11 for mixing the diluent solvent 10 and the paint 5 is provided. Further, the valve body 7 has a flow path 12 extending from the dilution solvent inlet 9 to the mixing chamber 11 and the coating material outlet 6 from the mixing chamber 11.
And a flow path 14 from the paint inlet 2 to the mixing chamber 11.

The flow path 14 from the paint inlet 2 to the mixing chamber 11 and the flow path 4 from the paint inlet 2 to the paint return port 3 are linearly arranged in the valve body 7. And these flow paths 4, 1
In order to open and close 4 reciprocally, the paint needle valve 8
Cone valves 81 and 82 are formed at the middle and lower ends,
Valve seats 71 and 72 are formed on the valve body 7.

A diluting solvent needle valve 15 that opens and closes the diluting solvent inlet 9 is installed in the passage 12 from the diluting solvent inlet 9 to the mixing chamber 11. The conical valve 151 is provided at the lower end of the diluting solvent needle valve 15. Are formed. Further, a valve seat 73 is formed on the valve body 7. A housing 1 is provided above the valve body 7.
6 is fixedly installed, and in the housing 16, a pressure receiving plate 17 that slidably connects two independent paint needle valves 8 and a diluent solvent needle valve 15 is arranged so as to be vertically movable. There is. The pressure receiving plate 17 is pushed up by the pressure air introduced into the pilot air inlet 1.

A push plate 18 is fixed to the upper end of the paint needle valve 8, and a compression spring 19 having a relatively high elasticity is arranged between the upper surface of the pressure receiving plate 17 and the lower surface of the push plate 18. A compression spring 20 having a relatively low elasticity is arranged between the upper surface of the push plate 18 and the inner surface of the housing 16. Further, a push plate 21 is fixed to the upper end of the dilution solvent needle valve 15, and a compression spring 22 is also arranged between the upper surface of the push plate 21 and the inner surface of the housing 16. A shoulder portion 23 that restricts upward movement of the push plates 18 and 21 is provided on the upper portion of the housing 16.

A connection plate 24 having a mixing chamber 11 formed therein is joined to the lower portion of the valve body 7, and the internal flow path 13 is formed below the connection plate 24.
A manifold plate 25 having a spiral structure is joined to the.

"Operation" In the above-mentioned configuration, when coating a complicated-shaped portion of a coating object such as a door end portion of the automobile body 121, a pillar portion, a press line portion, etc., where coating film dripping is to be prevented, a high-viscosity paint is used. Used. First, the CPU 104 reads the coating condition data set in the memory substrate 103 based on the input data such as the body type and the coating color input from the external input 101 from the input substrate 105. Next, the CPU 104
Outputs this coating condition data to the external output 102 through the bus line 130, and at the same time, the discharge amount control board 10
7, frequency converter 109, motor 111, gear pump 1
12, by controlling the paint mixing valve 114, the trigger / dump valve 115, and the painting gun 116.
Spray paint 21. This automatic spray coating system is the same as the current system.

With respect to general parts of the automobile body 121 and parts having a gentle shape in comparison with parts where quality is important, the smoothness of the painted skin can be improved by using a low-viscosity paint. In this case, the high-viscosity paint is supplied to the mixing valve 114 by the automatic spray coating system, but the shape of the body and the addition amount of the diluting solvent are previously examined by the graphic terminal 117, and the set addition amount data is used as the memory substrate 103. The CPU 104 reads the addition amount data from the memory substrate 103 because it is stored in the memory. Next, the CPU 104 outputs the output substrate 10
6, digital-analog conversion board 108, electro-pneumatic converter 1
10, air operated paint regulator 113
And the mixing valve 114 is controlled, and the dilution solvent tank 1
After the diluting solvent from 20 is mixed into the mixing valve 114 from another system, the low-viscosity paint obtained by mixing the high-viscosity paint and the diluting solvent is mixed with the trigger / dump valve 115 and the coating gun 116.
After that, it is spray-coated on the car body 121.

The paint mixing valve 114 performs a discharge operation as shown in Table 1 based on whether low pressure air or high pressure air applied to the pilot air inlet 1 is turned on or off.

According to this embodiment, the paint viscosity, that is, the amount of the diluent solvent added can be freely changed and set according to the shape part of the automobile body 121, so that the smoothness of the coated skin is improved,
There is an advantage that variation in smoothness can be reduced. If an ordinary paint valve that cannot be mixed with a diluting solvent is used, 3 to 4 paint valves and 3 to 4 paint circulation systems are required per paint color. According to the embodiment, since the paint mixing valve 114 having a special structure for performing the three functions of discharging and circulating the paint and mixing and non-mixing the diluent solvent at the time of discharging the paint is used, the capital investment amount is also increased. It has the advantage that it can be implemented at the same level as it is.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of a control system for carrying out the method of the present invention, and FIG. 2 is a sectional view showing the structure of a paint mixing valve in this embodiment. 104 ... CPU, 114 ... Paint mixing valve, 11
6 ... Painting gun, 119 ... Paint tank, 120 ... Diluting solvent tank, 121 ... Automotive body.

Claims (1)

[Claims] 1. A paint mixing valve for switching the discharge and circulation of paint so that the paint viscosity is increased in a complicated shape part of an object to be coated and the paint viscosity is lowered in a gentle shape part. An automatic spray coating method characterized by controlling the addition amount of a diluent solvent to be mixed with.