JP3405493B2 - Rotary atomizing electrostatic coating equipment - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rotary atomizing electrostatic coating device used for vehicle body coating in automobile manufacturing processes, for example.

[0002]

2. Description of the Related Art FIG. 3 is a diagram showing an example of a conventional rotary atomizing electrostatic coating apparatus. The rotary atomizing electrostatic coating apparatus 100 shown in the figure is a cup-shaped member fixed to a rotary shaft 101. A spray head 102, a high voltage generator 103 for applying a high voltage between the rotating shaft 101 and an object to be coated (not shown), and a paint supply nozzle 104 for supplying paint into the spray head 102 rotating at high speed. ing.

The spray head 102 is made of, for example, an aluminum alloy. Further, the rotary shaft 101 and the high voltage generator 103
A protective resistor 105 is provided between the and.

The annular space 1 of the spray head 102 rotating at high speed
The paint is supplied from the paint supply nozzle 104 supplied to the inside 02a through a large number of paint outflow holes 102c provided at the bottom of the inner peripheral surface 102b of the spray head 102, flows out along the inner peripheral surface 102b, and is sprayed by centrifugal force. Tip 102d of head 102
And reaches the end portion 102d to become negatively charged paint particles, which are discharged toward the object to which the high voltage positive side (for example, 0V side) of the high voltage generator 103 is applied. Become.

An example of such a rotary atomizing electrostatic coating device is described in Japanese Patent Application Laid-Open No. 63-229163.

[0006]

However, in the conventional rotary atomizing electrostatic coating apparatus as described above, since the spray head 102 made of metal such as aluminum alloy is used,
The tip end side (spray head side) has a larger charging capacity than the protective resistor 105, and there is a risk of sparking. Since energy at that time is large, it is difficult to reduce the distance from the spray head 102 to the object to be coated. In addition, there is a problem that electric charge may leak through the paint, especially when a low-resistance paint such as water-based paint is used.
The problem was to solve these problems.

[0007]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned conventional problems, and is capable of preventing sparks due to an increase in charge capacity of a spray head and at the time of using a low resistance paint. An object of the present invention is to provide a rotary atomizing electrostatic coating device capable of preventing charge leakage.

[0008]

According to a first aspect of the present invention, there is provided a rotary atomizing electrostatic coating device having a rotating spraying head, wherein the spraying head is cup-shaped. The main body part is molded with resin, electrodes are provided on almost the entire back surface of the main body part, and the inner surface of the spray head has a configuration in which the flight trajectory of the paint particles and the streamline of the ion air are substantially matched. As claimed in claim 2, the tip of the electrode is
It is configured to be located behind the tip of the main body,
According to a third aspect, the electrode is formed of a half-resistor, and the above-mentioned structure is a means for solving the problem.

[0009]

In the rotary atomizing electrostatic coating apparatus according to claim 1 of the present invention, since the cup-shaped main body portion of the spray head is made of resin, the charge capacity in the spray head is reduced,
Prevent the occurrence of sparks. Further, since the electrode is provided on almost the entire back surface of the main body portion, the paint and the electrode do not come into contact with each other, and the leakage of electric charge is prevented especially when the low resistance paint is used. Further, since the inner surface of the spray head is formed so that the flight path of the paint particles and the streamline of the ion air are substantially the same, the charge amount of the paint particles is increased. Further, as in the rotary atomizing electrostatic coating apparatus according to claim 2 of the present invention, the tip of the electrode is located rearward of the tip of the main body, so that the contact between the paint and the electrode can be made more reliable. To prevent leakage of charge, especially when using low resistance paints. Further, by using an electrode composed of a half-resistor as in the rotary atomizing electrostatic coating device according to the third aspect, the electrode itself serves as a protective resistance.

[0010]

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a rotary atomizing electrostatic coating device according to the present invention will be described below with reference to the drawings.

The rotary atomizing electrostatic coating apparatus shown in FIG. 1 has a hollow rotary shaft 1 driven by an air motor, a spray head 2 fixed to the tip of the rotary shaft 1, and a rotary shaft 1. High voltage generator 3 for applying a high voltage to an object to be coated (not shown)
Further, there is provided a paint supply pipe 4 for supplying paint into the spray head 2 rotating at high speed.

A protective resistor 5 is provided between the rotary shaft 1 and the high voltage generator 3. Further, the paint supply pipe 4 is inserted into the rotary shaft 1 at a coaxial position and in a non-rotating state, and the paint supply pipe 4 is provided with a discharge end portion from the tip end of the rotary shaft 1 so that the paint can be supplied into the spray head 2. It is provided in a protruding state.

The spray head 2 has a cup-shaped main body portion 2a.
Is made of a synthetic resin, and an electrode 2b made of a half-resistor is provided on almost the entire rear surface thereof. The tip of the rotary shaft 1 is brought into contact with the electrode 2b and is connected to the rotary shaft 1. There is.

Further, the spray head 2 has a partition wall portion 2c at the center of the main body portion 2a, a paint supply chamber 2d is formed on the back surface side (right side in FIG. 1) of the partition wall portion 2c, and the partition wall portion 2c is formed. 2c
A plurality of paint outflow holes 2e are formed in the outer peripheral portion of the base material at regular intervals in the circumferential direction.

Further, the inner peripheral surface 2h of the spray head 2 is
From the center toward the outside, the flight path of the paint particles during electrostatic coating, which will be described later, and the streamline of ion air generated from the tip 2f of the electrode 2d are made to substantially coincide with each other.

The tip portion 2f of the electrode 2b is located slightly rearward of the tip portion 2g of the body portion 2a, and is normally maintained at a negative high voltage of about -30 to -90 kV with respect to the object to be coated. To be done. At this time, the resistance value of the electrode 2b made of a half-resistor is about 10 MΩ.

Although not shown, an annular air cylinder for discharging shaping air toward the object to be coated is provided on the outer peripheral side of the spray head 2 and is formed by the shaping air from this air cylinder. The air layer regulates the discharge direction of the paint particles and forms a spray pattern.

In the rotary atomizing electrostatic coating apparatus having the above structure, the paint supplied from the paint supply pipe 4 into the supply chamber 2d of the spray head 2 rotating at a high speed flows through the paint outflow hole 2e of the spray head 2. As a result, it flows out along the inner peripheral surface 2h, reaches the tip portion 2g of the spray head 2 by centrifugal force, becomes negatively charged paint particles from the tip portion 2g, and becomes a high voltage of the high voltage generator 3. The positive side (for example, 0 V side) is discharged toward the object to be coated, and is sucked and adhered to the object to be coated.

At this time, in the rotary atomizing electrostatic coating apparatus, since the cup-shaped main body portion 2a of the spray head 2 is made of resin, the charge capacity of the spray head 2 is reduced and sparks may occur. Moreover, since the electrode 2b made of a half-resistor is provided on the back surface of the spray head 2, the electrode 2b
As a result, the electric system is protected by itself functioning as a protective resistance, and the tip portion 2f of the electrode 2b is protected by the main body portion 2.
Since it is located rearward of the tip portion 2g of a, the paint and the electrode 2b do not come into contact with each other, and charge leakage does not occur especially when a low-resistance paint such as an aqueous paint is used. .

Further, in the rotary atomizing electrostatic coating device,
As shown in FIG. 1, the inner surface of the spray head 2 has a trajectory F1 of the paint particles forming the outer peripheral portion of the spray pattern and the electrode 2
Since the shape is such that the flow line F2 of the ion air generated from the tip portion 2f of d is made to substantially coincide with each other, the paint particles are efficiently charged, thereby increasing the charge amount of the paint particles. The coating efficiency will be further improved.

In addition, as shown in FIG. 2, by arranging the tip 2f of the electrode 2b further rearward than the tip 2g of the main body portion 2a, the paint and the electrode 2b are more difficult to contact. This may be preferable, for example, when an aqueous paint is used.

[0023]

As described above, according to the rotary atomizing electrostatic coating apparatus according to the first aspect of the present invention, since the resin is used for the cup-shaped body portion of the spray head, the spray head is used. It is possible to reduce the charge capacity in the ,, thereby, it is possible to prevent the occurrence of sparks, further, since there is no occurrence of sparks, it is possible to reduce the distance between the spray head and the object to be coated, It can also contribute to improving the coating efficiency. Also, since the electrode is provided on almost the entire back surface of the spray head, it is possible to bring the paint and the electrode into a non-contact state, especially when using a low-resistance paint such as an aqueous paint. It is possible to prevent the occurrence of electric charge leakage through the paint. Further, since the inner surface of the spray head is formed so that the flight trajectory of the paint particles and the streamline of the ion air are substantially coincident with each other, the paint particles are efficiently charged and the charge amount of the paint particles is increased. It is possible to further improve the coating efficiency.

According to the rotary atomizing electrostatic coating apparatus of the second aspect of the present invention, since the tip of the electrode is located rearward of the tip of the main body, the coating material at the tip of the spray head is It is possible to more reliably prevent contact with the electrodes, and it is possible to completely prevent the occurrence of charge leakage through the paint. Further, according to the rotary atomizing electrostatic coating device of the third aspect of the present invention, since the electrode composed of the half-resistor is adopted, the electrode itself can act as a protective resistance, thereby protecting the electric system. The good functioning of the device can always be maintained.

[0025]

[Brief description of drawings]

FIG. 1 is a sectional view illustrating an embodiment of a rotary atomizing electrostatic coating device according to the present invention.

FIG. 2 is a cross-sectional view illustrating another example of the structure of the tip of the spray head.

FIG. 3 is a sectional view illustrating a conventional rotary atomizing electrostatic coating device.

[Explanation of symbols]

2 spray head 2a Body part (of spray head) 2b (spray head) electrode 2f electrode tip 2g Body tip 2h inner surface (of spray head)

─────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-8-150352 (JP, A) JP-B 38-24710 (JP, B1) (58) Fields investigated (Int.Cl. ⁷ , DB name) B05B 5/00-5/16

Claims (3)

(57) [Claims] 1. A rotary atomizing electrostatic coating apparatus having a rotating spray head, wherein a main body of the spray head having a cup-like shape is made of resin, and an electrode is provided on almost the entire back surface of the main body. The rotary atomizing electrostatic coating device is characterized in that the inner surface of the spray head has a shape in which the flight trajectory of the paint particles and the streamline of the ion air are substantially aligned with each other. 2. The rotary atomizing electrostatic coating device according to claim 1, wherein the tip of the electrode is located rearward of the tip of the main body. 3. The rotary atomizing electrostatic coating device according to claim 1, wherein the electrode is composed of a half-resistor.