JPH11104526A - Rotary atomizing electrostatic coating machine - Google Patents

Abstract

(57) [Problem] To provide a rotary atomizing electrostatic coating machine capable of suppressing generation of spark from the tip of a rotating shaft. SOLUTION: A hollow rotating shaft 2 made of a metal material, a semiconductive bell head 1 attached to a tip of the rotating shaft 2, and a non-conductive material inserted at least in the tip of the rotating shaft 2 are used. And a paint feed tube 3 comprising:
The rotary shaft 2 is a rotary atomizing electrostatic coating machine whose tip is covered with a non-conductive material or a semi-conductive material.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a rotary atomizing electrostatic coating machine.

[0002]

2. Description of the Related Art As shown in FIG. 4, a bell head body 21c made of a resin material and a bell head 21 made of a semiconductive film 21d formed on the outer peripheral surface of the bell head body 21c.
Japanese Patent Application Laid-Open No. 8-150352
It is known from U.S. Pat. Since the bell head 21 is made of a resin material or a semiconductive material having a higher resistance value than a metal material, a spark is less likely to occur between the bell head 21 and a grounded object than a rotary atomizing electrostatic coating machine having a metal bell head. .

[0003]

However, the conventional rotary atomizing electrostatic coating machine has the following problems. Bell head 21
Is required to be manufactured precisely because it is supported by an air bearing and rotates at a high speed, and is formed of a metal material. Therefore, even if the bell head 21 is formed of a resin material or a semiconductive material, when the ground object approaches the rotary atomizing electrostatic coating machine, as shown by a dotted line in FIG. There is a possibility that a spark may be generated from the tip of the rotating shaft 22 through the paint ejection hole 21a or the self-cleaning hole 21b provided in the bell head. An object of the present invention is to provide a rotary atomizing electrostatic coating machine that can suppress generation of spark from the tip of a rotating shaft.

[0004]

The present invention to achieve the above object is as follows. (1) A hollow rotating shaft made of a metal material, a semiconductive bell head attached to a tip of the rotating shaft, and a paint feed inserted through the rotating shaft and having at least a tip made of a non-conductive material. A rotary atomizing electrostatic coating machine, comprising: a tube; and a rotating shaft whose tip is covered with a non-conductive material or a semi-conductive material. (2) A semi-conductive bell head having a hollow rotating shaft made of a metal material, a mounting portion for the rotating shaft, and a tapered portion attached to the tip of the rotating shaft; and a bell head inserted through the rotating shaft. And a paint feed tube having at least a tip portion made of a non-conductive material, wherein the bell head has a hollow long axis portion between the attachment portion and the tapered portion, Machine.

In the rotary atomizing electrostatic coating machine of the above (1), since the tip of the rotating shaft made of a metal material is covered with a non-conductive material or a semi-conductive material, a grounded object (such as an object to be coated) is formed. ), The distance from the ground object to the metal part of the rotating shaft is longer than when the rotating shaft is not covered with a non-conductive or semi-conductive material. Of sparks can be suppressed. The above (2)
In the rotary atomizing electrostatic coating machine, since the length of the bell head in the axial direction is increased by providing the hollow long shaft portion between the mounting portion of the bell head and the tapered portion, an earth object is approached. However, since the distance from the ground object to the metal rotary shaft is longer than that of a bell head having no long shaft portion, it is possible to suppress the occurrence of sparks from the tip of the rotary shaft.

[0006]

FIG. 1 shows a rotary atomizing electrostatic coating machine according to a first embodiment of the present invention, and FIG. 2 shows a rotary atomizing electrostatic coating machine according to a second embodiment of the present invention. Reference numeral 3 relates to a rotary atomizing electrostatic coating machine according to a third embodiment of the present invention. The first and second embodiments correspond to claim 1, and the third embodiment corresponds to claim 2. Portions common to all embodiments of the present invention are denoted by the same reference numerals throughout all embodiments.

First, the structure of a portion common to all embodiments of the present invention will be described with reference to FIGS. The rotary atomizing electrostatic coating machine according to the embodiment of the present invention includes a bell head 1 for atomizing paint.
A hollow rotary shaft 2 attached to the tip of the bell head 1 and rotating integrally with the bell head 1, an air motor 8 (including an air bearing for rotatably supporting the rotary shaft) for rotating the rotary shaft 2; , A paint feed tube 3 made of a non-conductive material that extends to the inside of the bell head 1 and supplies paint to the bell head 1, a high voltage generator 4 for generating a high voltage applied to the bell head 1, and a casing 5 And Further, an air cap 6 having an air nozzle 6a for ejecting shaping air forward from the outer peripheral end of the bell head 1 toward paint scattered radially outward.
Having. The air cap 6 is made of a non-conductive material. The bell head 1 has a mounting portion 11 to which the rotating shaft 2 is attached, and a tapered portion 12 whose diameter is increased toward the tip. Mounting part 11
A projection 13 is formed at the front end of the bell head 1 so as to project toward the axial center of the bell head 1. The protrusion 13 has a hole at the center, and the paint feed tube 3 is inserted into the hole. The bell head 1 has a hub 14 facing the paint feed tube 3 in front of the paint feed tube 3, and the center of the rear surface of the hub 14 projects rearward. The hub 14 is provided with a paint outlet 1a through which paint passes through the outer periphery,
A self-cleaning hole 1b for passing a cleaning agent is provided at the center.

The bell head 1 may be formed entirely of a semi-conductive material, or the main body of the bell head 1 may be formed of a non-conductive material and provided with a film made of a semi-conductive material on the outer peripheral surface of the bell head body. It has conductivity and receives electric charge from the rotating shaft 2 and transmits it to paint scattered from the outer peripheral end of the bell head 1. When a film of a semiconductive material is provided on the outer peripheral surface of the bell head main body, the film is in contact with the rotating shaft at one end. The semiconductive material forming the bell head 1 is a material obtained by adding carbon to a phenol resin, a material obtained by adding carbon to an epoxy resin, a material obtained by adding carbon to polyether ether ketone, and the like. The non-conductive material forming the bell head 1 is polyimide, polyether ether ketone, or the like.

An external thread is formed on the outer periphery of the tip of the rotary shaft 2, and a female screw is formed on the inner surface of the mounting portion 1 of the bell head 1, so that the rotary shaft 2 is connected to the bell head 1.

The non-conductive material forming the paint feed tube 3 is, for example, polyimide, polyether ether ketone, or the like.

When the paint is applied, the paint is ejected from the paint feed tube 3 and hits the rear surface of the hub 14 so that the hub 14
Flows along the outer peripheral portion along the inner surface of the tapered portion 1e of the bell head 1 through the paint ejection hole 1b and reaches the outer peripheral end. The electrostatic charge transmitted from the high voltage generator 4 to the bell head 1 through a rotating shaft or the like is centrifugal force It is given together with. The paint to which the electrostatic charge has been imparted scatters outward in the radial direction, and immediately thereafter is blown forward by shaping air, adheres to the work, and paints the work.

Next, a configuration specific to each embodiment of the present invention,
The operation will be described. In the first embodiment of the present invention, as shown in FIG. 1, the projecting portion 13 has a covering portion 13a extending rearward from the rear surface. The covering portion 13a is formed in a ring shape at a position separated from the inner peripheral surface of the mounting portion 11 by the thickness of the rotating shaft 2 inward in the radial direction. Therefore, the distal end of the metal rotary shaft 2 has an outer peripheral surface coupled to the mounting portion 11 of the bell head 1, a front end surface covered with the projection 13 of the bell head 1, and an inner peripheral surface covered with the covering portion 13a. . However, the front end face of the rotating shaft 2 and the rear face of the projection 13,
The inner peripheral surface of the rotating shaft 2 and the covering portion 13a are not necessarily in close contact.

The operation of the first embodiment will be described with reference to the mounting portion 11 made of a non-conductive material or a semi-conductive material, and the projecting portion 1.
3 and the covering portion 13a covers the metal portion at the tip of the rotating shaft 2, and the distance from the object to be coated to the metal portion of the rotating shaft is such that the rotating shaft is not covered with a non-conductive material or a semi-conductive material. Since it is longer than in the case, generation of spark from the tip of the rotating shaft 2 is suppressed.

In the second embodiment of the present invention, as shown in FIG. 2, a coating film 7 made of a non-conductive material or a semi-conductive material is provided on the front end face and the inner peripheral face of the tip of the rotating shaft 2a. ing.
The outer peripheral surface of the tip of the rotating shaft 2 is connected to the mounting portion 11 of the bell head 1.

Regarding the operation of the second embodiment of the present invention, the metal portion at the tip of the rotating shaft 2 is covered with a non-conductive material or a semi-conductive material, and the portion from the workpiece to the metal portion of the rotating shaft is covered. Since the distance is longer than when the rotating shaft is not covered with a non-conductive material or a semi-conductive material, generation of spark from the tip of the rotating shaft 2 is suppressed.

In the third embodiment of the present invention, as shown in FIG. 3, a hollow long shaft portion 15 is provided between the mounting portion 11 of the bell head 1 and the tapered portion 12. Due to the long shaft portion 15, the distance from the paint jetting out from the tip of the paint feed tube 3 and colliding with the rear surface of the hub 14 becomes longer than before. In addition, the air cap 6 also has a longer axial length.

Regarding the operation of the third embodiment of the present invention, even when the object to be coated and the bell head are close to each other, the long shaft portion 15 is provided, so that the front end of the rotary shaft 2 is more advanced than the conventional bell head. Is increased, and the distance from the tip of the metal rotary shaft 2 to the object to be coated is longer than that of a conventional bell head, so that the generation of sparks from the tip of the rotary shaft 2 is suppressed.

[0018]

According to the first aspect of the present invention, the tip of the metal rotary shaft is covered with a non-conductive material or a semi-conductive material. The generation of spark can be suppressed. According to the rotary atomizing electrostatic coating machine of the second aspect, by providing the hollow long axis portion between the mounting portion of the bell head and the tapered portion, the distance from the object to be coated to the tip of the rotary shaft is higher than before. Since it becomes longer, generation of spark from the tip of the rotating shaft can be suppressed.

[Brief description of the drawings]

FIG. 1 is a sectional view of a bell head portion of a rotary atomizing electrostatic coating machine according to a first embodiment of the present invention.

FIG. 2 is a side view showing a half of a rotating shaft of a rotary atomizing electrostatic coating machine according to a second embodiment of the present invention in cross section.

FIG. 3 is a sectional view of a rotary atomizing electrostatic coating machine according to a third embodiment of the present invention.

FIG. 4 is a sectional view of a bell head portion of a conventional rotary atomizing electrostatic coating machine.

[Description of Signs] 1 Bell head 2 Rotary shaft 3 Paint feed tube 11 Mounting part 12 Tapered part 15 Long shaft part

Claims (2)

[Claims] 1. A hollow rotating shaft made of a metal material, a semiconductive bell head attached to a tip portion of the rotating shaft, and a semi-conductive bell head inserted through the rotating shaft, at least a tip portion made of a non-conductive material. And a paint feed tube, wherein the rotating shaft has a tip covered with a non-conductive material or a semi-conductive material. 2. A semi-conductive bell head, comprising: a hollow rotary shaft made of a metal material; a bell head attached to a tip end of the rotary shaft, and a mounting portion to the rotary shaft and a tapered portion; A paint feed tube having at least a distal end portion made of a non-conductive material inserted therein, wherein the bell head includes a hollow long axis portion between the mounting portion and the tapered portion, Electric painting machine.