JPH09192546A - Cleaning of rotary atomizing head rear face of rotary atomization electrostatic coating device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a sticking cleaning agent from dripping to a face to be coated and also prevent a coat defect from occurring during a coating process by setting the pressure of a shaping air during cleaning to a prescribed one lower than the pressure of a shaping air during coating, in a method for cleaning the rear face of a rotary atomizing head to be used for a rotary atomization electrostatic coating device. SOLUTION: The cleaning of a rotary atomizing head rear face is performed between a coating process and a following coating process, and also while a shaping air is ejected from a shaping air nozzle 7. During the coating process, a solenoid valve 17 is opened and a solenoid valve 16 is closed at the time of coating, and the pressure of the shaping air is made higher than about 1.5kg/cm<2> . On the contrary, the solenoid valve 17 is closed and the solenoid valve 16 is opened, and the pressure of the shaping air is regulated to 0.5-1.5kg/cm<2> at the time of cleaning. Thus, the convolution of a cleaning agent into the shaping air after being ejected from an atomizing head rear face cleaning nozzle 2 is inhibited by lowering the pressure of the shaping air during cleaning, and consequently, the cleaning agent does no longer stick to an air cap 3. After the cleaning process, a solenoid valve 29 is opened to purge the cleaning agent from a hose connected to the atomizing head rear face cleaning nozzle 2.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rotary atomizing head back surface cleaning method for a rotary atomizing electrostatic coating apparatus.

[0002]

2. Description of the Related Art Japanese Utility Model Laid-Open No. 62-48458 discloses a rotary atomizing electrostatic coating device. As shown in FIG. 7, the atomizing head back surface cleaning nozzle 52 is provided so as to face the back surface of the rotating atomizing head 51, and the rotary atomizing head 51 is stopped when coating is stopped during coating of the object to be coated. While rotating, the cleaning agent 53 is sprayed from the atomizing head back surface cleaning nozzle 52 and the shaping air 56 is sprayed from the shaping air nozzle 55 formed in the air cap 54 to clean the rotating atomizing head back surface.

[0003]

However, the conventional cleaning of the back surface of the rotary atomizing head has the following problems. Firstly, as shown in FIG. 7, the cleaning solvent ejected from the atomizing head back surface cleaning nozzle is caught up behind the atomizing head by the shaping air that is sprayed during cleaning, and the cleaning solvent is trapped in the air cap. A large amount will adhere. The adhered cleaning solvent gradually drops onto the body surface of the automobile during coating, causing a coating failure. Secondly, as shown in FIG. 8, since the atomizing head back surface cleaning nozzle is composed of a thin cylindrical nozzle, the sprayed cleaning solvent does not contact the entire outer surface of the atomizing head, and only a narrow area can be cleaned. . As a result, the paint accumulated without being washed off comes off from the rotary atomizing head during painting, which causes poor coating quality such as spots and color mixture. In order to prevent this, the atomizing head back surface cleaning nozzle angle and the rotating atomizing head rotation speed are adjusted so that the cleaning solvent ejected from the atomizing head back surface cleaning nozzle flows along the outer surface of the rotating atomizing head as much as possible. However, the setting is delicate and difficult, and a lot of man-hours are required for equipment installation and maintenance. Third,
Since the cleaning solvent is always filled in the atomizing head back surface cleaning nozzle, the cleaning solvent easily drops onto the body surface due to vibration during coating, causing a coating failure. An object of the present invention is to provide a method for cleaning the back surface of a rotary atomizing head of a rotary atomizing electrostatic coating apparatus, which can solve the above-mentioned problems, and particularly prevent the cleaning solvent from adhering to the air cap during cleaning. .

[0004]

The present invention to achieve the above object is as follows. Rotation of the atomizing head backside, which sprays the cleaning agent from the atomizing head backside cleaning nozzle provided facing the rotating atomizing head backside and ejects shaping air from the shaping air nozzle to wash the rotating atomizing head backside. A method for cleaning a back surface of an atomizing head, wherein a shaping air pressure during cleaning is set to be lower than a shaping air pressure during coating.

In the rotary atomizing head back surface cleaning method of the rotary atomizing electrostatic coating apparatus of the present invention described above, the shaping air pressure during cleaning is made smaller than the shaping air pressure during coating. As a result, the cleaning agent is less likely to be caught in the shaping air, and the cleaning agent is less attached to the air cap.
The adhered cleaning agent does not drop on the surface to be coated, and coating defects do not occur.

[0006]

1 to 6 show an embodiment of the present invention. First, a rotary atomizing electrostatic coating apparatus for carrying out the rotary atomizing head back surface cleaning method of the embodiment of the present invention will be described. In the rotary atomizing electrostatic coating apparatus of FIGS. 1 and 2, the rotary atomizing head 1 is fixed to the front end of the hollow shaft 10. The hollow shaft 10 is rotatably supported by a body 9, which is a stationary member, by an air bearing 8. The hollow shaft 10 is rotationally driven by an air motor 12, and the rotary atomizing head 1 is integrated with the hollow shaft 10 and rotated at high speed. A high voltage is applied to the rotary atomizing head 1 from a high voltage generator 4 (which may be embedded inside the body 9 or external), and is applied from the front end edge of the rotary atomizing head 1. Charge scattered paint. Reference numeral 5 is a resin cover made of an electrically insulating material.

A feed tube 6 for a paint and a cleaning agent (also called a cleaning solvent or thinner) is inserted through the hollow shaft 10.
When the paint is applied to the inside of the rotary atomizing head 1, the paint is applied to the inside of the rotary atomizing head 1, and the cleaning agent is supplied to clean the inner surface of the rotary atomizing head 1 during the cleaning. Paint feed tube 6
May be a multi-feed tube that passes through a single detergent feed tube.

An air cap 3 has a plenum chamber 11 inside and ejects shaping air from a number of shaping air nozzles 7 arranged on the same circumference, and a radius is generated by centrifugal force from the rotary atomizing head 1. Direct the flight pattern of the paint that scatters outwards toward the object in front. An atomizing head back surface cleaning nozzle 2 is provided so as to face the back surface of the rotary atomizing head 1, and paint applied to the back surface of the rotary atomizing head 1 during painting is applied to the object to be coated and the next object to be coated. Cleaning is performed by spraying a cleaning agent while the painting is stopped between painting of the object. One atomizing head back surface cleaning nozzle 2 is provided around the rotary atomizing head 1, and the cleaning agent ejected from the atomizing head back surface cleaning nozzle 2 is rotary atomized by the rotation of the rotary atomizing head 1. It hits the entire back surface of head 1.

The paint from the paint source 14 (including a feed pump) is supplied to the paint feed tube. A color change valve 27 and a flow control valve 2 are provided in the middle of the paint supply path.
6. An on / off solenoid valve 25 is provided in this order from upstream to downstream. When the paint feed tube is a multi-feed tube, a feed tube and a paint source are provided for different colors, and the flow control valve 26,
An on / off solenoid valve 25 is provided.

A cleaning agent is supplied from a common cleaning agent source 15 to the cleaning agent feed tube (for cleaning the inner surface of the rotary atomizing head) and the atomizing head back surface cleaning nozzle 2 (for cleaning the outer surface of the rotating atomizing head). To be done. A flow control valve 24 and an on / off solenoid valve 23 are provided in the middle of the cleaning agent supply path to the cleaning agent feed tube.
Are provided in order from upstream to downstream. In the middle of the cleaning agent supply path to the atomizing head back surface cleaning nozzle 2, a flow rate control valve 22,
The on / off solenoid valve 21 is provided in order from upstream to downstream.

Compressed air is supplied to the air motor 12, the air bearing 8, and the shaping air nozzle 7 from a common compressed air source 12. A pressure regulator 20 is provided in the compressed air supply path to the air motor 12. Air bearing 8
Compressed air is directly supplied from the compressed air source 12. However, a pressure regulator and a flow rate control valve may be provided in the compressed air supply path.

The compressed air supply path to the shaping air nozzle 7 is branched into a plurality of passages at a position separated from the shaping air nozzle 7 on the upstream side, and a pressure regulator and an on / off solenoid valve are provided in order from upstream to downstream in each branch passage. To be The pressure regulator of each branch passage changes the set pressure. For example, one branch passage is provided with a pressure regulator 18 and an on / off solenoid valve 16 sequentially from upstream to downstream, and another branch passage is provided with a pressure regulator 19 and an on / off solenoid valve 17 sequentially from upstream to downstream. Therefore, the set pressure of the pressure regulator 18 and the set pressure of the pressure regulator 19 are different. For example, the set pressure of the pressure regulator 18 is set lower than the set pressure of the pressure regulator 19. The setting pressure of the lower pressure regulator 18 is 0.5 to 1.5 kg / c
It is said to be m ² . The reason for setting the lower limit to 0.5 kg / cm ² is that if it is lower than that, the cleaning agent for cleaning the inner surface of the atomizing head does not blow forward and scatters in the centrifugal direction and adheres to the air cap 3, This is because the robot that has the painting machine attached and the car body are dirty. Further, the reason why the upper limit is set to 1.5 kg / cm ² is that if it is higher than that, the cleaning agent on the outer peripheral surface of the atomizing head may be caught in the air cap 3 and adhere to the air cap 3 to drip during coating. .

The compressed air supply path from the compressed air supply source 13 is connected to the downstream portion of the electromagnetic valve 21 of the cleaning agent supply path to the atomizing head back surface cleaning nozzle 2, and is connected to the upstream portion of the connection portion. An on / off solenoid valve 29 is provided. By opening the solenoid valve 29 and closing the solenoid valve 21,
The cleaning agent from the atomizing head back surface cleaning nozzle 2 to the connecting portion can be purged.

Each solenoid valve 20, 21, 23, 25, 16,
17, 29 and the color change valve 27 are operated by a command from the control device 28, and if necessary, the flow control valves 22, 2
4, 26, pressure regulators 18 and 19 are also control devices 28
It is designed to be activated by a command from. Then, the control device 28 sends the shaping air having a high pressure to the shaping air nozzle 7 through the branch passage in which the pressure regulator 19 having the higher set pressure is installed during the coating execution, and the rotary atomizing head back surface cleaning is performed by the cleaning agent. Controls the solenoid valves 16 and 17 so as to send shaping air having a low pressure to the shaping air nozzle 7 through the branch passage in which the pressure regulator 18 having a lower set pressure is installed.

As shown in FIG. 3, the rotary atomizing head back surface cleaning nozzle 2 has a shape of the cleaning agent jetting outlet, and becomes a pattern 30 in which the cleaning agent jetted from the jetting agent spreads away from the jetting outlet after being jetted. It is a wide-angle nozzle so that it hits the entire back surface of the head 1. The spray pattern of the cleaning agent sprayed from the atomizing head back surface cleaning nozzle 2 may be an elliptical pattern 31 as shown in FIG. 4 or a circular pattern 32 as shown in FIG.

In order to ensure that the cleaning agent sprayed from the rotary atomizing head back surface cleaning nozzle 2 hits the entire length of the back surface of the rotary atomizing head 1, instead of using the wide-angle nozzle as described above, it is shown in FIG. As described above, a plurality of cleaning nozzles 33, 34, 35 may be provided so that the cleaning agent ejected from each cleaning nozzle may hit a different portion in the axial direction on the back surface of the rotary atomizing head 1. In this case, from multiple cleaning nozzles at the same time,
Alternatively, the cleaning agent is ejected in order from the cleaning nozzle 2 on the inner peripheral side. When providing a plurality of cleaning nozzles, it is not always necessary to use wide-angle nozzles.

Next, a method for cleaning the back surface of the rotary atomizing head of the embodiment of the present invention which is carried out by using the above apparatus will be described. The rotary atomizing head back surface cleaning method of the embodiment of the present invention is the same as the rotary atomizing head back surface 1
A spraying agent is sprayed from the atomizing head back surface cleaning nozzle 2 provided opposite to the nozzle, and shaping air is sprayed from the shaping air nozzle 7 to clean the rotary atomizing head back surface 1. This is a method for cleaning the back of the head, in which the shaping air pressure during cleaning is lower than the shaping air pressure during coating. When cleaning,
Using a wide-angle nozzle as shown in FIG. 3, or FIG.
A plurality of nozzles 3 arranged on different circumferences as shown in FIG.
By using 3, 34 and 35, the jet cleaning agent is made to hit the entire axial length of the rotary atomizing head 1. During cleaning, the rotary atomizing head 1 is rotated, so that the cleaning agent hits the entire back surface of the rotary atomizing head 1.

Washing is performed between paintings,
This is performed while ejecting shaping air from the shaping air nozzle 7. When cleaning, paint on / off solenoid valve 2
5 is closed. First, the electromagnetic valve 23 is opened to clean the inner surface of the rotary atomizing head 1, and then the electromagnetic valve 21 is opened to clean the back surface of the rotary atomizing head 1. The solenoid valve 17 is open and the solenoid valve 16 is closed at the time of painting, and the shaping air pressure is higher than about 1.5 kg / cm ² , but during cleaning, the solenoid valve 17 is closed and the solenoid valve 16 is open. The pressure is 0.
It is set to 5 to 1.5 kg / cm ² . By lowering the shaping air pressure during cleaning to 0.5 to 1.5 kg / cm ² , entrapment of the cleaning agent sprayed from the atomizing head back surface cleaning nozzle 2 into the shaping air is suppressed, and the cleaning agent becomes air. It will not adhere to the cap 3. After cleaning, the electromagnetic valve 29 is opened to purge the cleaning agent in the atomizing head back surface cleaning nozzle 2 and the hose connected thereto. This prevents the cleaning agent filled in the atomizing head back surface cleaning nozzle 2 from dropping during coating and causing a coating failure.

[0019]

According to the rotary atomizing head back surface cleaning method of the rotary atomizing electrostatic coating apparatus of the present invention, the shaping air pressure during cleaning is made smaller than the shaping air pressure during coating.
The entraining force of shaping air during cleaning is reduced,
As a result, the cleaning agent is less likely to be caught in the shaping air, the amount of the cleaning agent attached to the air cap is reduced, and the deposition of the attached cleaning agent on the surface to be coated during coating and the occurrence of coating defects do not occur.

[Brief description of the drawings]

FIG. 1 is a sectional view and a system diagram of an apparatus for carrying out a rotary atomizing head back surface cleaning method according to an embodiment of the present invention.

FIG. 2 is a front view of the apparatus of FIG.

FIG. 3 is a side view showing a cleaning agent spray pattern of the atomizing head back surface cleaning nozzle in FIG.

FIG. 4 is a side view of an example of a cleaning agent spray pattern of the wide-angle nozzle of FIG.

5 is a side view of another example of the cleaning agent jetting pattern of the wide-angle nozzle of FIG.

6 is a side view when a plurality of atomizing head back surface cleaning nozzles are provided instead of the wide-angle nozzle of FIG.

FIG. 7 is a partial cross-sectional view of an apparatus for performing a conventional rotary atomizing head back surface cleaning method.

FIG. 8 is a side view of a rotary atomizing head showing a range that can be cleaned by a conventional rotary atomizing head back surface cleaning method.

[Explanation of symbols]

 1 Rotating Atomizing Head 2 Atomizing Head Backside Cleaning Nozzle 3 Air Cap 4 High Voltage Generator 5 Resin Cover 6 Feed Nozzle 7 Shaping Air Nozzle 8 Air Bearing 9 Body 10 Hollow Shaft 11 Plenum Chamber 12 Air Motor 13 Compressed Air Source 15 Cleaning Agent Source 16, 17, 29 ON / OFF solenoid valve 18, 19 Pressure regulator 28 Control device

Claims (1)

[Claims] 1. A rotary atomizer for cleaning a back surface of a rotary atomizing head by ejecting a cleaning agent from a atomizing head rear surface cleaning nozzle provided opposite to the rotary atomizing head rear surface and ejecting shaping air from a shaping air nozzle. A method for cleaning a back surface of a rotary atomizing head of an electro-coating device, wherein a shaping air pressure at the time of cleaning is made smaller than a shaping air pressure at the time of coating.