JPH08155349A - Electrostatic coating method and electrostatic coating machine used therein - Google Patents

Abstract

PURPOSE: To make the front surface of a rotary atomizing head for spraying a coating material hardly adherable with a coating material and to easily wash away the coating material even if the coating material adheres thereon. CONSTITUTION: An air chamber 11 communicating with a center air injection hole 8 for preventing the adhesion of the coating material opened at the center in the front surface part of the rotary atomizing head 2 for atomizing the coating material is formed in this rotary atomizing head. The coating material is supplied to a coating material chamber 10 via a coating material pipe 9 and is sprayed from a coating material spray port 6 while the air is injected from the center air injection hole 8 by supplying the compressed air to the air chamber 11 via an air passage 12 formed within a tubular revolving shaft 4 to be mounted with the rotary atomizing head 2 at the time of coating. A washing liquid is supplied to the coating material chamber 10 and the air chamber 11 via a coating material pipe 9 and the air flow passage 12 at the time of washing.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrostatic coating method in which shaping air is sprayed from the outside of a rotary atomizing head for atomizing paint to suppress the spread of sprayed paint, and an electrostatic coating used therefor. Regarding the machine.

[0002]

2. Description of the Related Art A rotary atomizing head to which a high voltage is applied is rotated at a high speed to atomize the paint by its rotating force and electrostatic force, and at the same time electrostatically apply the paint to a work applied to the opposite pole. Electrostatic coating, which is designed to be applied, not only has good coating efficiency and little waste of paint, but also can form a uniform coating film, so high coating quality is required such as in automobile bodies. It is often used for painting.

When performing this electrostatic coating,
By spraying shaping air from the outside toward the sprayed paint from the rotary atomizing head and suppressing the spread of the sprayed paint, the coating patterns can be different according to the size of the object to be coated, the number of coating machines installed, and the installation interval. The size of the painting pattern is adjusted so that the two overlap exactly.

At this time, since the rotary atomizing head is rotated at a high speed of 20,000 to 30,000 revolutions per minute, its centrifugal force and the air flow of shaping air act on the front side of the rotary atomizing head. The air existing in the air is blown to the outside, a negative pressure air pocket is formed on the front side of the rotary atomizing head, and the sprayed paint is entangled therein, and is easily attached to the front of the rotary atomizing head. Therefore, conventionally, a through hole is formed in the center of the front surface of the rotary atomizing head,
Every time the rotary atomizing head is cleaned, the cleaning liquid is made to flow to the front side for cleaning.

[0005]

However, if the colors are frequently changed in the case of multicolor coating, the coating machine is washed every time so that the stain does not become severe, but the same color continues. In this case, the amount of paint adhered increases, and the adhered paint may drip onto the object to be coated during coating, resulting in defective coating. In particular, when electrostatic coating is performed with a single color paint, it is not necessary to frequently wash the paint, and therefore the growth of the adhered paint is fast and the coating failure is remarkable. Therefore, it is a technical object of the present invention to make it difficult for the paint to adhere to the front surface of the rotary atomizing head and to easily wash and remove the paint even if it adheres.

[0006]

In order to solve this problem, the present invention relates to a paint which is inserted into a rotary atomizing head attached to the tip end of a tubular rotary shaft of an air motor. In the electrostatic coating method in which the paint supplied through the pipe is sprayed from the peripheral portion of the tip of the rotary atomizing head, and shaping air is sprayed from the outside of the rotary atomizing head to suppress the spread of the sprayed paint, An air chamber is formed in the rotary atomizing head, the air chamber communicating with a center air injection hole for preventing paint adhesion, which is opened in the center of the front surface of the head, and at the time of coating, an air passage formed in the tubular rotary shaft While supplying compressed air to the air chamber through the center air injection hole and supplying the paint to the paint chamber through the paint pipe and spraying it from the paint spray port, at the time of cleaning, the paint pipe And air flow And supplying a cleaning liquid to the paint chamber and the air chamber through the.

[0007]

According to the present invention, the center air is jetted from the center of the front surface of the rotary atomizing head toward the air pocket where the pressure becomes low at the time of coating, the pressure drop is prevented, and the spray paint is caught. Since it is driven out by the center air, the paint is less likely to adhere to the front part of the rotary atomizing head. Furthermore, since the cleaning liquid is supplied to the air chamber during cleaning, the cleaning liquid oozes out from the center air injection port and the front part of the rotary atomizing head is cleaned.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be specifically described below based on embodiments shown in the drawings. FIG. 1 is a sectional view showing an electrostatic coating machine used in the electrostatic coating method according to the present invention.

In the figure, reference numeral 1 denotes an electrostatic coating machine in which a rotary atomizing head 2 to which a high voltage is applied is attached to the tip of a tubular rotary shaft 4 of an air motor 3. The rotary atomizing head 2 has its tip. A paint spray port 6 is built in the machine body 5 with its surface exposed, and a paint spray port 6 for electrostatically atomizing and spraying the paint supplied through the tubular rotary shaft 4 is formed in a peripheral edge portion of the machine body 5. At the same time, the inner air injection port 7 for injecting stirring air toward the paint sprayed from the paint spray port 6 is formed in an annular shape along the inside of the paint spray port 6 and is formed in a mortar shape. A center air injection hole 8 for injecting paint adhesion preventing air is formed in the center of the front surface portion 2a.

The rotary atomizing head 2 has a paint chamber 10 which receives paint from a paint pipe 9 which is inserted into and supported by a tubular rotary shaft 4 in a non-contact state, and rotates with respect to the paint chamber 10. An air chamber 11 located on the tip side of the atomizing head 2 is formed. The paint chamber 10 is communicated with the paint spray / spray port 6 through a radially formed paint passage 10a, and an air chamber 11 is formed as a radially formed air passage 11a.
Through the inner air injection port 7 and the center air injection hole 8.

An air pipe (air flow path) 12 for supplying compressed air to the air chamber 11 is inserted inside the paint pipe 9 and has a double pipe structure in which the paint pipe 9 is an outer pipe and the air pipe 12 is an inner pipe. Has been formed. And paint pipe 9
Is opened in the paint chamber 10, and the tip of the air pipe 12 is inserted into the through hole 14 formed in the partition wall 13 of the paint chamber 10 and the air chamber 11 in a non-contact state and opened in the air chamber 11. ing. In addition, a shaping air injection port 15 is formed along the outer periphery of the rotary atomizing head 2 in the machine body 5 to inject compressed air from the outside toward the paint sprayed from the paint spray port 6 to adjust the spray pattern. Has been done.

The above is an example of the constitution of the electrostatic coating machine according to the present invention. Next, the electrostatic coating method according to the present invention will be described with reference to the time chart shown in FIG. First, at the time of coating, a high voltage is applied to the rotary atomizing head 5 to rotate the atomizing head 5 at a predetermined number of revolutions, while the paint is supplied from the paint pipe 9 serving as an outer pipe to the coating chamber 10 and the inner pipe is Naru Air Pipe 1
2, compressed air is supplied to the air chamber 11, and compressed air is further supplied to the shaping air injection port 15 (FIG. 3: T).
₁ ~T _2).

At this time, the paint supplied to the paint chamber 10 reaches the tip of the paint spray port 6 through the paint passage 10a and is atomized by its rotational force and electrostatic force. Also,
The compressed air supplied from the air pipe 12 to the air chamber 11 passes through the air passage 11a and is jetted from the inner air jet port 7 and at the same time, is jetted from the center air jet hole 8. Further, shaping air is ejected from the shaping air spray port 15.

Accordingly, compressed air is jetted from both the outside and the inside of the paint spray port 6, and the paint is atomized not only by the rotational force and electrostatic force but also by the air pressure. Even if lowered, the paint can be atomized and sprayed. Further, since the air jetted from the inner air jet port 7 becomes a vortex and agitates the spray paint from the inside thereof, even when the metallic paint is sprayed, the metal pieces are uniformly dispersed without being biased in one direction. . Furthermore, since air is also injected from the center air injection hole 8 of the rotary atomizing head 2, an air pocket having a low pressure is not formed on the front side of the rotary atomizing head 2, and therefore the paint is sprayed by the rotary atomizer. It becomes difficult to adhere to the front surface portion 2a of the fossilized head 2.

Next, when the coating is stopped by stopping the supply of the paint from the paint pipe 9, and when the cleaning is performed, the rotary atomizing head 2 is rotated and high-pressure cleaning air and the cleaning liquid are alternately supplied from the paint pipe 9. (FIG. 3: T _{3 to} T ₄ ). Thereby, the paint pipe 9, the paint chamber 10 and the paint spray port 6
The paint adhering to is removed by washing. At the same time, the cleaning liquid is supplied from the air pipe 12 at a low pressure to exude the cleaning liquid from the center air injection hole 8 and the cleaning liquid is transmitted from the center of the front portion 2a of the rotary atomizing head 2 toward the peripheral edge thereof, and the rotary atomizing head The paint adhering to the front part 2a of No. 2 is removed, and finally air is supplied to blow out the cleaning liquid remaining in the air pipe 12 and the air chamber 11 to complete the cleaning.

At this time, the front portion 2 of the rotary atomizing head 5
If a is formed by recessing in a mortar shape, the cleaning liquid that has exuded from the center air injection hole 8 formed in the center thereof flows along the inclined surface without being sprayed, and therefore adheres to the front surface portion 2a. Can reliably remove the paint. In the embodiment, the case where not only the center air injection hole 8 but also the inner air injection port 7 is formed in the air chamber 11 has been described, but the case where the inner air injection port 7 is not necessary may be used. However, in that case, it is necessary to form a flow path that allows the cleaning liquid supplied during cleaning to escape.

[0017]

As described above, according to the present invention, the center air is jetted from the central portion of the rotary atomizing head during coating, so that a negative pressure air pocket is provided in front of the rotary atomizing head. Therefore, the amount of paint sprayed from the paint injection port on the front side of the rotary atomizing head is significantly reduced, and even if it adheres, the central part of the rotary atomizing head is washed during cleaning. It has an excellent effect that the front part of the rotary atomizing head can be easily washed by letting out the washing liquid from the inside.

[Brief description of drawings]

FIG. 1 is a sectional view showing an example of an electrostatic coating machine according to the present invention.

FIG. 2 is a time chart showing an example of an electrostatic coating method according to the present invention.

[Explanation of Codes] 1 ... Electrostatic coating machine 2 ... Rotating atomizing head 3 ... Air motor 4 ... Tubular rotating shaft 6 ... Paint spray port 8 ... Center air injection hole 9. ..Paint pipe 10 ... Paint chamber 11 ... Air chamber 12 ... Air pipe (air flow path) 15 ... Shaping air injection port

Claims (2)

[Claims] 1. A paint chamber (10) for a rotary atomizing head (2) attached to the tip of a tubular rotary shaft (4) of an air motor (3).
In addition, the paint supplied through the paint pipe (9) inserted through the tubular rotary shaft (4) is sprayed from the peripheral portion of the tip of the rotary atomizing head (2), and outside the rotary atomizing head (2). In the electrostatic coating method in which shaping air is sprayed from the spraying paint while suppressing the spread of the sprayed paint, a center air spray for preventing paint adhesion is opened in the center of the front part of the rotary atomizing head (2). An air chamber (11) communicating with the hole (8) is formed, and at the time of coating, compressed air is supplied to the air chamber (11) through an air flow path (12) formed in the tubular rotary shaft (4). While spraying air from the center air injection hole (8), the paint is supplied to the paint chamber (10) through the paint pipe (9) and sprayed from the paint spray port (6). The paint chamber (10) through the paint pipe (9) and the air flow path (12)
And an electrostatic coating method comprising supplying a cleaning liquid to the air chamber (11). 2. A paint chamber (10) of a rotary atomizing head (2) attached to the tip of a tubular rotary shaft (4) of an air motor (3).
In addition, the paint supplied through the paint pipe (9) inserted through the tubular rotary shaft (4) is sprayed from the peripheral portion of the tip of the rotary atomizing head (2), and outside the rotary atomizing head (2). In an electrostatic coating machine that sprays shaping air from the spraying machine while suppressing the spread of sprayed paint, a center air jet for preventing paint adhesion is opened in the center of the front part of the rotary atomizing head (2). An air chamber (11) communicating with the hole (8) is formed, and the air chamber (11) passes through the tubular rotary shaft (4) while the paint is being supplied to the paint chamber (10). An electrostatic coating machine is characterized in that an air flow path (12) for supplying compressed air is formed.