JPH11123349A - Rotary atomizing electrostatic coating machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the leakage of charge through a coating by installing an internal bell head which is formed from an internal cup part and an internal hub which is installed in the inside of the cup part opposite to a coating feed tube and has a coating discharge hole in a peripheral part. SOLUTION: Since an internal bell head 8 rotates with a rotary shaft 2, and an external bell head 1 is installed outside the internal bell head 8, a coating scattered from the head 8 passes through the coating discharge hole 1c of the lead 1 and is atomized again to be scattered radially outward from the peripheral end of the head 1. Since the flow of the coating from a coating tank to the peripheral end of the head 1 through a coating feed tube 3 is interrupted when the coating is scattered from the peripheral end of the head 8, the leakage of charge through the conductive coating is prevented. Therefore, only by adding a simple improvement to a conventional rotary atomizing electrostatic coating machine, coating with a conductive coating can be done.

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 11 of a rotary atomizing electrostatic coating machine includes a cup portion 11a and a hub 11b provided inside the cup portion 11a opposite to a paint feed tube 13. Become. Bell head 1 when applying paint
1 is rotated by the rotation of the rotating shaft 12, the paint supplied from the paint tank connected to the earth and discharged from the paint feed tube 13 hits the rear surface of the hub 11b,
It flows to the outer periphery along the rear surface of the hub 11b, passes through the paint discharge holes 11c provided in the outer periphery of the hub 11b, and scatters outward from the outer end of the bell head 11 in the radial direction. Since the bell head 11 is provided with an electrostatic charge generated from the high-pressure generator, the paint scatters from the outer peripheral end of the bell head 11 and is charged, and adheres to an object to be coated.

[0003]

In the conventional rotary atomizing electrostatic coating machine, the amount of paint passing through the paint discharge hole 11c of the hub 11b is smaller than the amount of paint discharged from the paint feed tube 13. The paint accumulates on the rear surface, and the paint 19 flows without interruption from the paint tank to the outer peripheral end of the bell head 11 (see FIG. 4). Therefore, when a conductive paint such as a water-based paint is applied, the electrostatic charge applied to the bell head 11 leaks through the conductive paint that flows without interruption from the paint tank connected to the ground to the outer end of the bell head. Resulting in. as a result,
There is a problem that electrostatic painting cannot be performed. SUMMARY OF THE INVENTION It is an object of the present invention to provide a rotary atomizing electrostatic coating machine capable of preventing a charge from leaking through a paint by interrupting a flow of the paint from a paint feed tube to an outer peripheral end of a bell head.

[0004]

The present invention to achieve the above object is as follows. (1) A hollow rotary shaft, a stationary paint feed tube passing through the rotary shaft, an external cup portion attached to a tip of the rotary shaft, and the external cup portion facing the paint feed tube. And an external bell head comprising an external hub having a paint discharge hole on the outer peripheral portion provided inside the outer bell head, inside the outer bell head, having the same axis as the rotating shaft, an inner cup part, A rotary atomizing electrostatic coating machine, comprising: an internal bell head that is provided inside the internal cup portion to face the paint feed tube and includes an internal hub having a paint discharge hole on an outer peripheral portion. (2) a hollow rotary shaft, a stationary paint feed tube passing through the rotary shaft, and a bell head attached to a distal end of the rotary shaft, wherein the paint feed tube has an orifice at a distal end; Is a rotary atomizing electrostatic coating machine.

[0005] In the rotary atomizing electrostatic coating machine of the above (1), since the paint is atomized by the internal bell head which rotates with the rotation of the rotating shaft and the flow of the paint is interrupted, the electric charge is prevented from leaking through the paint. be able to. In the rotary atomizing electrostatic coating machine of the above (2), the paint is extruded at a high pressure by the orifice provided at the tip of the paint feed tube and is atomized to interrupt the flow of the paint, so that the electric charge leaks through the paint. Can be prevented.

[0006]

1 and 2 relate to a rotary atomizing electrostatic coating machine according to a first embodiment of the present invention, and FIG. 3 shows a rotary atomizing electrostatic coating machine according to a second embodiment of the present invention. Get involved. The first embodiment corresponds to claim 1, and the second 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 FIG. The rotary atomizing electrostatic coating machine according to the embodiment of the present invention has a bell head (external bell head) 1.
A hollow rotary shaft 2 having a bell head 1 attached to the tip and rotating integrally with the bell head 1, an air motor 7 for driving the rotary shaft 2 to rotate (including an air bearing rotatably supporting the rotary shaft), and a rotary shaft 2 And a paint feed tube 3 extending to the inside of the bell head 1 to supply 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. Further, the bell head 1 has an air cap 6 having an air nozzle 6a for ejecting shaping air forward toward the paint scattered outward in the radial direction from the outer peripheral end. The bell head 1 includes a cup 1a, and a hub (external hub) 1b provided inside the cup 1a in front of the paint feed tube 3 so as to face the paint feed tube 3. The hub 1b has a plurality of paint discharge holes 1c on the outer periphery. The bell head 1 includes a bell head main body 1d formed of a non-conductive resin, and a coating 1e formed of a semiconductive material (for example, phenol resin containing carbon) or a conductive material formed on the surface of the bell head main body 1d. Consists of The coating 1e comes in contact with the rotating shaft 2 at the upper end, receives the electric charge from the rotating shaft 2, and transmits it to the paint scattered from the outer peripheral end of the bell head 1. Since the bell head body 1d is made of resin, the bell head 1 is lighter in weight than a metal bell head. The paint feed tube 3 is made of, for example, a non-conductive material and communicates with a paint tank (not shown). The paint tank is connected to earth. The rotating shaft 2 is made of metal and has conductivity, and its tip is covered with a wall 1f made of a non-conductive material provided in a tubular shape with a predetermined interval radially inward from the rear inner wall surface of the bell head 1. I have. The wall 1f is connected to the bell head main body 1a at the front end, and is formed integrally with the bell head main body 1a. When the conductive paint is flowing in the paint feed tube, the wall 1f maintains an insulation distance between the conductive paint and the rotating shaft.

When the paint is applied, the paint passes through the paint discharge hole 1c provided in the hub 1b, travels along the inner wall surface of the bell head 1, reaches the outer peripheral end, and travels from the high voltage generator 4 to the bell head 1 through the rotating shaft 2 and the like. Static charge is applied together with the centrifugal force. The paint to which the electrostatic charge has been imparted scatters outward in the radial direction, and is immediately blown forward by shaping air discharged from the air nozzle 6a, and adheres to the work to be coated, thereby painting the work to be coated.

Next, a configuration specific to each embodiment of the present invention,
The operation will be described. In the first embodiment of the present invention, an inner bell head 8 having the same axis as the rotating shaft 2 is provided inside a bell head (external bell head) 1 as shown in FIG. The inner bell head 8 includes an inner cup portion 8a and a paint feed tube 3 in front of the paint feed tube 3.
And an internal hub 8b provided inside the internal cup portion 8a in opposition to the internal hub 8b. The inner hub 8b has a plurality of paint discharge holes 8c on the outer periphery.

Next, the operation of the first embodiment of the present invention will be described. When the paint is applied, the paint discharged from the paint feed tube 3 does not directly strike the rear surface of the hub (external hub) 1b of the bell head (external bell head) 1, but first strikes the rear surface of the internal hub 8b of the internal bell head 8. Since the inner bell head 8 rotates together with the rotating shaft 2, the inner hub 8
The paint 9 that has hit the rear surface flows to the outer peripheral portion along the inner hub rear surface 8b, passes through the paint discharge hole 8c, and forms a mist from the outer peripheral end of the internal bell head 8 as shown in FIG. Scatter. Since the outer bell head 1 is provided outside the inner bell head 8, the inner bell head 8 is provided.
Paint scattered from the paint outlet 1c of the external bell head 1
Through the outer bell head 1, it again forms a mist from the outer peripheral end and scatters radially outward. Since the flow of the paint from the paint tank to the outer peripheral end of the bell head 1 through the paint feed tube 3 is interrupted when the paint is scattered from the outer peripheral end of the inner bell head 8, the electric charge leaks through the conductive paint. It is. Therefore, the conductive paint can be applied by the rotary atomizing electrostatic coating machine according to the embodiment of the present invention, which is a simple modification of the conventional rotary atomizing electrostatic coating machine.

In the second embodiment of the present invention, as shown in FIG.
Is provided. The orifice 3a is formed such that the pressure of the paint is increased and the paint discharged from the tip of the paint feed tube 3 is atomized.

Next, the operation of the second embodiment of the present invention will be described. The paint 9 is extruded at a high pressure by the orifice 3a and atomized as shown in FIG. 3, and the flow of the paint from the paint tank through the paint feed tube 3 to the outer peripheral end of the bell head 1 is interrupted. Leakage of charge is cut off. Therefore, the conductive paint can be applied by the rotary atomizing electrostatic coating machine according to the embodiment of the present invention, which is a simple modification of the conventional rotary atomizing electrostatic coating machine.

[0013]

According to the first aspect of the present invention, since the paint is atomized by the internal bell head provided inside the external bell head, the flow of the paint is interrupted, and the electric charge leaks through the paint. Can be prevented. Claim 2
According to the rotary atomizing electrostatic coating machine, the paint is extruded from the paint feed tube at high pressure and atomized by the orifice provided at the tip of the paint feed tube.
It is possible to prevent the flow of the paint from being interrupted and prevent the electric charge from leaking through the paint.

[Brief description of the drawings]

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

FIG. 2 is a sectional view of a bell head portion of the rotary atomizing electrostatic coating machine according to the first embodiment of the present invention.

FIG. 3 is a sectional view of a bell head portion of a rotary atomizing electrostatic coating machine according to a second embodiment of the present invention.

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

[Explanation of symbols]

 Reference Signs List 1 bell head (external bell head) 1a cup part (external cup part) 1b hub (external hub) 1c paint discharge hole 2 rotating shaft 3 paint feed tube 3a orifice 8 internal bell head 8a internal cup part 8b internal hub 8c paint discharge hole

Claims (2)

[Claims] 1. A hollow rotary shaft, a stationary paint feed tube passing through the rotary shaft, an external cup portion attached to a tip end of the rotary shaft, and the outside facing the paint feed tube. An external hub provided on the inner side of the cup portion and having an outer peripheral portion having a paint discharge hole on the outer peripheral portion. Inside the external bell head, the outer bell head has the same axis as the rotating shaft, and the inner cup portion A rotary atomizing electrostatic coating machine, comprising: an internal bell head, which is provided inside the internal cup portion so as to face the paint feed tube and has an internal hub having a paint discharge hole on an outer peripheral portion. 2. A hollow rotary shaft, a stationary paint feed tube passing through the rotary shaft, and a bell head attached to a tip of the rotary shaft, wherein the paint feed tube has an orifice at the tip. , A rotary atomizing electrostatic coating machine.