JPS60122069A - Method and apparatus for coating - Google Patents

Abstract

PURPOSE:To obtain always an ideal appearance of the coating without chapping and dripping by controlling the supply of a solvent in accordance with the temp. in a coating chamber. CONSTITUTION:The amt. of a solvent contained in a paint is previously set so that an appropriate appearance of the coating can be obtained at a minimum temp. such as 20 deg.C which is considered to be the lowest temp. in a coating chamber 3. When the temp. in the coating chamber 3 is elevated, the temp. is detected by a temp. detector 21, and a flow rate controller 19 is opened to start the supply of a solvent from a solvent supply nozzle 14. The flow area of the flow rate controller 19 is increased with the increase in temp. in the coating chamber 3. Accordingly, the amt. of the solvent to be supplied from the solvent supply nozzle 14 is increased with the increase in temp. in the coating chamber 3. A high-quality coated film can be formed by setting the amt. of the solvent so that the optimum viscosity can be obtained when the material to be coated is coated.

Description

[Detailed description of the invention] Industrial applications The present invention relates to a coating method and a coating device.

Prior Art A liquid paint is atomized, and then this atomized paint is applied to a coating material W.
<In the so-called spray painting method in which a coating film is formed by spraying, the temperature of the environment in which spraying is performed is a major factor in determining the appearance quality of the object to be coated. In other words, when the environmental temperature is high, the volatilization of the solvent contained in the paint is accelerated during the process from when the paint is atomized to when it is applied to the object to be coated. The viscosity of the paint increases abnormally, and as a result, the fluidity of the paint film is impaired, resulting in insufficient smoothness of the paint film, resulting in so-called rough skin. On the other hand, when the environmental temperature is low, the viscosity of the paint does not increase sufficiently, causing the paint film to flow too much, resulting in poor paint appearance such as sagging or running. Therefore, keeping the environmental temperature constant is an important condition for ensuring stable coating appearance quality without causing "rough skin,""sagging," or "flow." However, for example, car yj? In a large-scale painting process such as Dee painting, maintaining the temperature of the painting environment constant throughout the year requires a large air conditioning system and energy, which is extremely difficult to achieve.

Therefore, in reality, the environmental temperature is between 20°C and 30°C throughout the year.
The current situation is that the ideal coating appearance quality cannot always be stably ensured because it fluctuates within a range of ℃.

OBJECTS OF THE INVENTION The object of the present invention is to provide a coating method and a coating apparatus in which an ideal coating appearance quality can always be obtained by controlling the supply of solvent lIk according to the coating environment temperature.

Structure of the Invention The structure of the present invention is such that the surface of the object to be coated is coated by mixing the paint supplied from the paint supply nozzle and the solvent supplied from the solvent supply nozzle and spraying the mixture onto the surface of the object to be coated. In the coating method described above, the temperature in the one-bath work chamber in which the paint supply nozzle, solvent supply nozzle, and the object to be coated are arranged is detected, and as the temperature in the painting work chamber rises, the temperature of the solvent supplied from the solvent supply nozzle is increased. The reason is that the amount has been increased.

Furthermore, the configuration of the present invention is such that a rotary atomizing electrostatic coating device equipped with a spray head is disposed in a painting work chamber, and a temperature detector for detecting the temperature inside the painting work chamber is disposed. To supply paint to the spray head, install a paint supply nozzle and a solvent supply nozzle for supplying solvent to the spray head, connect the paint supply nozzle to the paint source, and connect the solvent supply nozzle to the solvent supply nozzle. A flow control valve is connected to the solvent source via a pipe, and a flow control valve is inserted into the solvent supply pipe to increase the flow area when the temperature in the painting work chamber rises in response to an output signal from a temperature sensor.

Embodiment Referring to FIG. 1, 】 is a painting booth, 2 is a rotary bar electrostatic coating device located in an empty working room 3 formed inside the painting booth, 4 is a paint tank, and 5 is a solvent tank. are shown respectively. Referring to FIG. 2, which shows an enlarged view of section A in FIG.
A rotating shaft 8 rotatably supported within the housing 6
A spray head 9 is fixed to the tip of the spray head 9 by a nut 10, and this rotating shaft 8 is rotationally driven by a turbine 7. Rotation +! ti+8 is -60KV ~ -120I (V t7
) is connected to a high voltage generator (not shown) that generates a negative high quasi-pressure, and therefore the spray head 9 has a rotating ftMil 8
A negative +l'ii 'il pressure is applied via. The spray head 9 rotates with a cup-shaped inner peripheral surface]], iI! A paint supply nozzle for supplying paint into this annular space 2] 3,
A solvent supply nozzle 14 for supplying a solvent is arranged. As shown in FIG. 1, the paint supply nozzle 13 is connected to the paint supply pipes 15, 1 and 1. The solvent supply nozzle 14 is connected to the paint tank 4 via a ring 16, and the solvent supply nozzle 14 is connected to the solvent tank 5 via a solvent supply pipe J7 and a solvent supply bong f1B. An electromagnetic flow control valve 19 is inserted into the solvent supply pipe 17 , and this flow control valve 19 is connected to an output terminal of an electronic control unit 20 .

On the other hand, a temperature detector 2] for detecting the temperature inside the painting work room 3 is arranged inside the painting work room 3, and this temperature sensor 2] is connected to an input terminal of the electronic control unit 20.

The flow rate control valve] 9 is actuated by the output signal of the temperature sensor 21, and increases the flow cross section of the solvent supply pipe 17 as the temperature in the coating work chamber 3 rises. Therefore, as the temperature in the painting chamber 3 increases, the amount of solvent supplied from the solvent supply nozzle 4 increases, while the path of the paint supplied from the paint supply nozzle 13 remains constant. .

As shown in FIG. 2, a large number of paint outlet holes 22 are formed at the innermost part of the inner circumferential surface of the spray head 9 defining the current space 2 over the entire circumference thereof. During painting work, the paint is delivered to the annular space of the spray head 9 which rotates at high speed from the paint supply nozzle 13]
Supplied within 2 days.

This paint then passes through the paint outflow hole 22 due to the centrifugal force generated by the rotation of the spray head 9 and flows out of the spray head 9 through the centrifugal force.
It flows out onto the shaped inner peripheral surface 11. Next, this paint is applied to the inner peripheral surface 1.
It spreads as a thin liquid film on the spray head 9 and then advances towards the peripheral edge 23 of the tip of the spray head 9 (7) and is released from the peripheral edge 23 in an atomized state.

As mentioned above, a negative pressure 11 is applied to the spray head 9, so that the atomized particles are negatively charged.

Normally, the object to be coated is at zero level, so the atomized particles are still at 1
B is attracted toward the object to be painted by the energy, and thereby the painting is performed.

- The solvent is supplied from the solvent supply nozzle] 4 into the annular space 12 in the same manner as in the case of painting F, and then passes through the paint outlet hole 22 and is discharged from the tip 1+'i of the spray head 9 11 from the striking part 23. . In this case, the paint and solvent are supplied from separate nozzles, but these f! 5 O'mi 1 and the solvent flow in the annular space 12, (λ family 1) IC outlet 22, in the trench where it is emitted from the spray head 9 and reaches the object to be coated, and in the groove where it reaches the object to be coated. mixed on the surface of the

By the way, the temperature inside the painting work room 3 is not constant and may fluctuate in the range of 20"C to 30"C throughout the year, or even more than this range.Therefore, in the present invention, the temperature inside the painting work room 3 In other words, in the present invention, the amount of solvent contained in the paint is controlled at the lowest temperature when the temperature inside the painting work chamber 3 is fluctuating, for example, at 20°C. The settings are made in advance so that an appropriate coating appearance quality can be obtained.When the temperature inside the coating work chamber 3 rises, this is detected by the temperature detector 21, and the flow rate control valve J9 is opened to open the solvent supply nozzle. The supply of solvent from 4 is started.The flow area of flow control valve 9 is increased by 'J1''9 as the temperature inside the coating work chamber 3 increases.
Therefore, as the temperature inside the coating work chamber 3 rises, the amount of solvent supplied from the solvent supply nozzle 4 is increased.

In this case, the amount of solvent to be supplied is set so that the viscosity of the paint is optimized when it is applied to the object to be coated.

Effects of the Invention If the mixing ratio of solvent and paint is kept constant, when the environmental temperature increases, the amount of solvent volatilized increases, resulting in a decrease in the viscosity of the paint and causing rough skin. The viscosity of the paint is maintained at an optimum level, and no roughness occurs.Furthermore, when the environmental temperature is low, the amount of solvent supplied decreases. Therefore, the paint does not flow too much and therefore does not cause paint (5,11-sagging) or "θi sagging". Therefore, no matter how the environmental temperature changes, Paint appearance quality can be ensured.

[Brief explanation of the drawing]

2! E 1 figure! 2M is an enlarged cross-sectional view of section A in FIG. 1. 2...Rotating atomization station 11 Shin U equipment 0.3...Western clothing work room 54...[Hayashi/Fri/ri, 5...Solvent tank, 9...
Spray head, ]; 3... C 1 supply nozzle, ] 4... Bath agent supply nozzle, 17... Solvent supply pipe, 9... First episode: 拉.

Claims (1)

[Claims] 1. A method for coating the surface of an object by mixing the paint supplied from a paint supply nozzle and the solvent supplied from a solvent supply nozzle and spraying the mixture onto the surface of the object. In the coating method described above, the temperature in the coating work chamber in which the paint supply nozzle, the solvent supply nozzle, and the object to be coated are arranged is detected, and as the temperature rises, the amount of solvent supplied from the solvent supply nozzle is increased. This is the painting method. 2 A rotary atomizing electrostatic 11L coating device equipped with a spray head is placed in the painting work chamber, and a temperature sensor for detecting the temperature inside the painting work chamber is placed, and the rotary atomizing electrostatic painting device is equipped with a Attach a paint supply nozzle for supplying paint and a lr supply nozzle for supplying a solvent to the spray head, connect the paint supply nozzle to a paint source, and connect the solvent supply nozzle to a solvent supply pipe. A coating device in which a flow rate control valve is connected to a solvent source through a solvent supply pipe and increases a flow area when the temperature in a coating work chamber increases in response to an output signal from the temperature sensor.