JPH09276750A - Rotary-atomization electrostatic coater - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide the rotary-atomization electrostatic coater capable of being lighted in weight. SOLUTION: A needle electrode 15 is opposed to the rotating shaft 2 or bell head 1 of this rotary-atomization electrostatic coater, and the bell head 1 is charged by utilizing a corona discharge directly or through the rotating shaft 2. Consequently, the bearing and bearing housing need not be formed from a metallic material, and the coater is remarkably lightened in weight by forming them from a ceramic or a resin.

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 capable of reducing the weight of an air motor.

[0002]

2. Description of the Related Art An outline of a rotary atomizing electrostatic coating apparatus, which has recently become mainstream, is shown in FIGS. The rotary atomizing electrostatic coating device mainly includes a bell head (atomizing head) 1, a rotary shaft 2, an air motor 3 ', a main body housing 4', a shaping air cap 5, a paint feed tube 6, a high voltage generator 7,
It is composed of The air motor 3'includes a radial bearing 8
′, Thrust bearing 9 ′, housings 10 ′ and 11 ′ for fixing these bearings, turbine drive air supply nozzle 13
including. As a bearing of the air motor 3'of the rotary atomizing electrostatic coating device, a static pressure air bearing is mainly used. The hydrostatic air bearing uses the air that is pressurized from the outside.
'Is supplied to the gap between the rotary shaft 2 and the rotary shaft 2 to levitate, and the rotation is non-contact and oil-free rotation. Further, the bell head 1 fastened to the rotary shaft 2 has a turbine blade 1 on the rotary shaft 2.
2 is driven by supplying compressed air. When the bell head 1 is charged to a high voltage, all the air motor components (excluding the bearing metal) are made of a conductive material (mainly metal material) (the housings 10 'and 11' are aluminum, the bearings 8'and 9'are (The gun metal) and the electrode pin 14 is brought into contact with the outer peripheral surface of the air motor 1.
In this case, the air layer in the gap between the bearings 8'and 9'and the rotating shaft 2 is thin, and the high voltage of the bearings 8'and 9'discharges, the insulation of the air layers is destroyed (dielectric breakdown), and the conductivity is reduced. Axis of rotation (S
US) 2, the bell head 1 is charged. The electrode pin (or spring, leaf spring, etc.) 14 cannot be brought into contact with the rotating shaft 2. If it contacts the rotating shaft 2,
This is because the pressing force acts on the rotary shaft 2 and the hydrostatic air bearing having a small load capacity is damaged.

[0003]

However, the conventional device has the following problems because the components of the air motor are made of a conductive material (mainly a metal material). Since the metal material has a large specific gravity, the weight of the air motor becomes heavy. Insulation material of sufficient thickness (in Fig. 4, main body housing 4'to prevent dielectric breakdown from around the air motor)
The material must be coated with, for example, polyethylene terephthalate, which makes the coating apparatus body large and heavy. It is an object of the present invention to provide a rotary atomizing electrostatic coating device capable of reducing the weight of an air motor, and hence the coating device.

[0004]

The present invention to achieve the above object is as follows. A rotary atomizing electrostatic coating device that supports and drives a rotating shaft having a bell head attached thereto by an air motor, wherein a needle electrode is provided facing the rotating shaft or the bell head, and the bell head is formed by utilizing corona discharge from the needle electrode.
A rotary atomizing electrostatic coating device with a structure that is charged directly or through a rotary shaft.

In the above apparatus, since the rotating shaft or the bell head is charged in a non-contact manner by utilizing corona discharge, the bearing and the housing of the air motor can be made of a non-conductive material such as ceramic or resin. It is possible to reduce the weight of the air motor and the rotary atomizing electrostatic coating device as compared with the metal material air motor.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A rotary atomizing electrostatic coating apparatus according to an embodiment of the present invention will be described with reference to the drawings. 1 shows a first embodiment of the present invention, and FIG. 2 shows a second embodiment of the present invention. Parts common to the first and second embodiments of the present invention are designated by the same reference numerals throughout the first and second embodiments of the present invention.
Further, the same reference numerals are given to the portions common to the embodiment of the present invention and the conventional apparatus.

First, a portion common to the first and second embodiments of the present invention will be described with reference to, for example, FIG. Referring to FIG. 1, a rotary atomizing electrostatic coating apparatus according to an embodiment of the present invention mainly comprises a bell head (atomizing head) 1 that is rotated by atomizing and scattering the paint, and a rotary shaft 2 having the bell head 1 attached to the front end. , An air motor 3 that rotatably supports and rotates the rotating shaft 2, a body housing 4 that houses the air motor 3, a shaping air cap 5 (according to FIG. 3) provided at the front end of the body housing 4, and a paint on the bell head 1. It comprises a paint feed tube 6 (according to FIG. 3) to be supplied, and a high voltage generator 7 for finally generating a high voltage for charging the bell head 1 to a high voltage. Air motor 3
Is a radial bearing 8 for rotatably supporting the rotary shaft 2, a thrust bearing 9, and a housing 1 for fixing these bearings.
0, 11, and a turbine drive air supply nozzle 13 for sending air to the turbine blade integrated with the rotary shaft 2. As the bearing of the air motor 3 of the rotary atomizing electrostatic coating device, a static pressure air bearing is mainly used. The static pressure air bearing uses air pressurized from the outside to form a gap (several to several degrees) between the bearing 8 and the rotary shaft 2.
100 μm thick) to make the rotary shaft 2 levitate, and the rotation is non-contact and oil-free rotation. In addition, the bell head 1 fastened to the rotary shaft 2 has a turbine blade 12 on the rotary shaft 2.
It is driven by supplying compressed air to.

The structure for charging the bell head 1 to a high voltage is provided with the needle electrode 15 facing the rotary shaft 2 or the bell head 1 (in the illustrated example, the needle electrode 15 faces the rotary shaft 2). However, it may be opposed to the bell head 1), a corona discharge from the needle electrode 15 (a type of discharge in gas, a high voltage (for example, thousands of volts) is applied to the needle electrode.
Is applied, the bell head 1 is charged directly or via the rotating shaft 2 by using the discharge that weakly emits light at the tip of the needle, which occurs before the spark discharge occurs.
The bell head 1 and the rotary shaft 2 are made of a conductive material (for example, SUS) as in the conventional case. The needle electrode 15 is connected to the high voltage generator 7.

With this structure, the bearings 8 and 9 and the bearing fixed housings 10 and 11 do not need to be conductive materials, and non-conductive materials (for example, resin or ceramics).
May be composed of In the embodiment of the present invention, the radial bearing 8 and the thrust bearing 9 are made of ceramic,
The radial bearing fixed housing 10 and the thrust bearing fixed housing 11 are made of resin (for example, polyethylene terephthalate). As a result, since the specific gravity of ceramics and resin is smaller than that of metal materials, the weight of the air motor 3 and the coating device is reduced as compared with the case of using conventional metal materials. The resin (for example, polyethylene terephthalate) is softer than the metal material and requires less processing time, so that the manufacturing cost is also reduced. further,
By reducing the conductive material, the capacitance of the device can be reduced and the device is easier to handle.

Next, parts unique to each embodiment of the present invention will be described. The first embodiment of the present invention shows the case where the air motor 3 and the main body housing 4 are separate bodies. The main body housing 4 is also made of resin (for example, polyethylene terephthalate). The high voltage generator 7 and the shaping air path 16 (see FIG. 3) are installed in the main body housing 4.
Since the radial bearing fixed housing 10 and the thrust bearing fixed housing 11, which are the outer peripheral portion of the air motor 3, are made of an insulating material such as resin, the main body housing 4 does not need to be thicker than the conventional one in terms of electrical insulation, and accordingly, the size is small. And weight reduction.

In the second embodiment of the present invention, a case where the resin portion (radial bearing fixed housing 10 and thrust bearing fixed housing 11) on the outer peripheral portion of the air motor 3 also serves as the main body housing and the main body housing is omitted is described. Shows. A high voltage generator 7 and a shaping air path 16 (see FIG. 3) are installed in the housing of the air motor 3. Since the main body housing is not provided, the size and weight of the device are greatly reduced accordingly.

[0012]

According to the apparatus of the present invention, since the bell head is charged by corona discharge by providing the needle-shaped electrode, it is not necessary to form the bearing and the bearing housing of the air motor from a metal material, and a lightweight material. The weight of the air motor and the coating device can be reduced by using, for example, ceramic or resin.

[Brief description of drawings]

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

FIG. 2 is a schematic sectional view of a rotary atomizing electrostatic coating device according to a second embodiment of the present invention.

FIG. 3 is an overall schematic sectional view of a conventional rotary atomizing electrostatic coating device.

FIG. 4 is a schematic sectional view of a conventional rotary atomizing electrostatic coating device.

[Explanation of symbols]

 1 Bell Head 2 Rotating Shaft 3 Air Motor 4 Body Housing 7 High Voltage Generator 8 Radial Bearing 9 Thrust Bearing 10 Radial Bearing Fixed Housing 11 Thrust Bearing Fixed Housing 12 Air Turbine 15 Needle Electrode

Claims (1)

[Claims] 1. A rotary atomizing electrostatic coating device in which a rotary shaft having a bell head mounted thereon is supported and driven by an air motor,
A rotary atomization characterized in that a needle electrode is provided so as to face the rotating shaft or the bell head, and the bell head is charged by using corona discharge from the needle electrode directly or through the rotating shaft. Electrostatic coating device.