JPH0641644Y2 - Electrostatic coating equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial application] The present invention is provided with an external electrode on the outside of a rotary atomizing head, and the rotary atomizing head is rotated at a high speed to charge atomized paint particles. The present invention relates to an electrostatic coating apparatus of a type in which charged paint particles are caused to fly along an electrostatic field between an external electrode and an article to be electrostatically applied to the article.

[Conventional technology]

Generally, an electrostatic coating device using a bell-type or disc-type rotary atomizing head rotates the rotary atomizing head at high speed to atomize the coating material into particles. It is designed to fly onto a coating and be electrostatically applied.

By the way, paints are roughly classified into water-based paints and metallic paints having a small electric resistance and solvent-based paints having a relatively large electric resistance.

When solvent-based paint is applied, the electrostatic coating device forms a static electric field between the rotary atomizing head and the object to be coated by directly applying a high voltage to the rotary atomizing head itself. As a result, the paint is atomized by the rotary atomizing head and is simultaneously charged. In this case, the paint directly becomes charged paint particles in the rotary atomizing head and flies along the electrostatic field to electrostatically adhere to the object to be coated.

On the other hand, when coating water-based paints and metallic paints, generally, an electrostatic coating device of a type having an external electrode on the outside of the rotary atomizing head is used. A discharge paint is formed by forming a discharge area and charging the paint particles atomized by the rotary atomizing head when passing through the corona discharge area and forming an electrostatic field between the external electrode and the object to be coated. The particles fly along this electrostatic field and electrostatically adhere to the object to be coated.

The reason why the method for charging the paint particles differs depending on the kind of paint is as follows. That is, the rotary atomizing head is supplied with the paint from the paint tank through the paint supply pipe, but in general, from the viewpoint of danger prevention, the paint supply pipe and the paint tank are used by being connected to the ground. Therefore, in the case of water-based paints and metallic paints with low electrical resistance, even if a high voltage is applied to the rotary atomizing head,
The rotary atomizing head is short-circuited to the ground potential via the paint in the paint supply pipe and cannot be charged. Therefore,
In this case, as described above, the external electrode is provided outside the rotary atomizing head, and the coating device of the type in which the paint particles are charged by the external electrode outside the rotary atomizing head is used.

On the other hand, many solvent-based paints have high electrical resistance, so the rotary atomizing head is short-circuited to ground potential via the paint in the paint supply pipe even if a high voltage is directly applied to the main body of the coating device. There is no such thing. Therefore, in the case of a solvent-based paint, a high voltage is applied to the rotary atomizing head itself without using an external electrode so that the rotary atomizing head atomizes the paint and simultaneously charges the same. .

FIG. 3 shows a conventional electrostatic coating apparatus used for coating water-based paints and metallic paints.

In the figure, reference numeral 1 is a main body of the coating apparatus, which is made of a metal cylinder forming a housing of the coating apparatus, and a tip end side of the main body 1 is a motor mounting for accommodating an air motor 2 for driving a rotary shaft 9 described later. Part 1A, the rear end side has a paint valve inside,
A valve mounting portion 1B for accommodating a cleaning valve and the like (not shown) is provided, and a manifold 1C and a mounting bracket 1D are provided at the rear end of the valve mounting portion 1B.

Reference numeral 3 denotes an insulative cover that covers the outer periphery of the coating apparatus main body 1, and the cover 3 is formed of resin into a cylindrical shape. The cover 3 has a body cover 4 for covering the motor mounting portion 1A and the valve mounting portion 1B, and a first shaping screwed to the front end side of the body cover 4 so as to surround the outer periphery of a rotary atomizing head 10 described later. An air nozzle 5 and a second shaping air nozzle 6 that is provided inside the first shaping air nozzle 5 and is sandwiched between the first shaping air nozzle 5 and the coating apparatus body 1. There is. Here, the first and second shaping air nozzles 5 and 6 have air blowing holes 7 between these nozzles 5 and 6 and air blowing holes 8 between the first shaping air nozzle 5 and the rotary atomizing head 10. The coating pattern sprayed from the rotary atomizing head 10 is formed into a circular shape by blowing air from the.

Reference numeral 9 denotes a rotary shaft, the base end side of the rotary shaft 9 is rotationally driven and supported by a static pressure bearing by an air motor 2 in the coating apparatus main body 1, and the front end side thereof projects forward from the front end side of the coating apparatus main body 1. ing.

Reference numeral 10 denotes a bell-shaped rotary atomizing head which is located on the front side of the coating apparatus main body 1 so as to be surrounded by the air shaping nozzles 6 and which is fixed to the front end side of the rotary shaft 9 and is driven to rotate at high speed. Paint is supplied to the rotary atomizing head 10 from a paint tank (not shown) via a paint supply pipe (not shown) to atomize the rotary, and to supply cleaning solvent and air for cleaning. It has become. Here, the paint supply pipe and the paint tank are used by being connected to the ground from the viewpoint of danger prevention.

Reference numeral 11 denotes an electrode supporting member provided on the outer periphery of the main body cover 4 of the cover 3, and the electrode supporting member 11 has an annular fixing portion 12 attached to the outer peripheral surface of the main body cover 4, and the fixing portion 12
An electrode attachment portion 13 having a larger diameter and an annular shape, and a support piece (not shown) for attaching and supporting the electrode attachment portion 13 to the fixing portion 12 coaxially.
It consists of and.

Reference numeral 14 denotes a needle-shaped external electrode attached to the electrode attachment portion 13, and a plurality of external electrodes 14 are provided at predetermined intervals in the circumferential direction of the electrode attachment portion 13 so as to be higher than the high voltage generator 15. By supplying a high voltage through the voltage cable 16, an electrostatic field is formed between the high voltage and the article to be coated 17.

Therefore, when coating is performed in the electrostatic coating apparatus of the prior art configured as described above, first, the high voltage generator 15
By applying a high voltage to the external electrode 14 from above, an electrostatic field is formed between the external electrode 14 and the object to be coated 17 and a corona discharge region is formed in the vicinity of the rotary atomizing head 10. next,
After the rotary atomizing head 10 is rotated, the paint is atomized by supplying the paint to the rotary atomizing head 10, and the atomized paint particles are charged by passing through the corona discharge region. After that, the object to be coated 17 is flown along the electrostatic field.
Electrostatically apply to.

[Problems to be solved by the device]

However, the above-mentioned conventional technique has the following problems.

That is, in the electrostatic coating device for coating the solvent-based paint, the high voltage is applied from the high voltage generator 15 to charge the rotary atomizing head 10, but at this time, the coating device body 1 itself is also at the same potential. Even if the metallic coating apparatus main body 1 is exposed to the outside without mounting the cover 3 because it is charged, the coating particle is repelled from the coating apparatus main body 1, so that the coating apparatus main body is exposed. It is unlikely that the front end side of the main body 1 of the coating apparatus is contaminated without being applied to No. 1.

On the other hand, in the electrostatic coating apparatus for coating water-based and metallic coatings, the high voltage is applied from the high voltage generator 15 to charge the external electrodes, but at this time, the coating apparatus main body 1 becomes the ground potential. In addition, the coating particles easily pass through the corona discharge region and become charged, and then are attracted to the coating apparatus main body 1 to be applied and stained to be contaminated. Therefore, in order to prevent the stain, it is essential to cover the coating apparatus body 1 with the insulating cover 3, but in this case, the cover 3 and the external electrode 14 are stained due to the following reasons. There is a problem.

That is, based on the high speed rotation of the rotary atomizing head 10, a so-called air pumping phenomenon occurs, in which a radial air flow is generated as shown by an arrow X in FIG. 9, and the surrounding air is entrained in the air flow X to cause a radial direction. Flows Y and Y'diffusing outwardly occur as a so-called air pumping phenomenon. As a result, the paint particles floating around the rotary atomizing head 10 are particularly entrained in the airflow Y'due to this air pumping phenomenon, and are polluted on the outer circumference of the front end side of the cover 3 as indicated by reference numeral 18. There is a problem.

Further, even if -90V is applied to the external electrode 14 side, the charged paint particles charged in the vicinity of the rotary atomizing head 10 are about -40KV, and between the external electrode 14 and the charged paint particles. Of course has a potential difference. Therefore, the charged paint particles are attracted to the external electrode 14 side, and there is also a problem that the paint particles adhere to the external electrode 14 as shown by reference numeral 19 and stain the same.

The present invention has been made in view of the above-mentioned drawbacks of the prior art,
Prevents the phenomenon that the outer circumference of the front end of the cover and the external electrodes are contaminated,
An object of the present invention is to provide an electrostatic coating device that can be maintained in a clean state.

[Means for Solving the Problems]

In order to achieve the above-mentioned object, an electrostatic coating device adopted by the present invention comprises a tubular coating device main body having an air motor for driving a rotary shaft therein, and a cover for covering at least the front end side of the coating device main body. A rotary mist that is located on the front end side of the main body of the coating device and is attached to a rotary shaft, and selectively atomizes any of water-based paint, metallic paint, and solvent-based paint to rotary atomize the selected paint. An atomizing head, an external electrode supporting member provided on the cover at a position radially outward of the rotary atomizing head, and a paint particle supported by the supporting member and atomized by the rotary atomizing head. It is composed of an external electrode which is electrified and is applied by flight to an object to be coated.

A feature of the present invention is that the support member is provided with an air chamber, and the support member is provided with a porous plate that blows out air from the air chamber to the front end side of the cover, and supplies air to the air chamber. Thus, air is blown out through the porous plate, and the outer circumference of the front end side of the cover is covered with an air flow, so that the coating particles are prevented from adhering to the cover and the external electrode.

[Action]

With this configuration, when air is supplied from the outside to the air chamber provided in the support member, this air passes through the porous plate and is uniformly dispersed and blown out from the front surface of the cover. Cover the outer circumference with an air stream. Therefore,
Even if the paint particles try to adhere to the cover or the external electrode, they are blocked by the air flow and do not adhere, so that the cover and the external electrode can be kept in a clean state.

〔Example〕

An embodiment of the present invention will be described below with reference to FIGS. 1 and 2. The same components as those of the conventional technique are designated by the same reference numerals and the description thereof will be omitted.

Reference numeral 21 denotes a porous plate used in the present embodiment. The porous plate 21 is formed of porous plastic having open cells, and has a cover insertion hole 21A having a diameter slightly larger than that of the main body cover 4 and an annular shape surrounding the cover insertion hole 21A. It is configured in a flat plate shape from the portion 21B. Here, the open cells mean cells having continuous air permeability. Then, as the porous plastic used in this example, a material which is not affected by a solvent, for example, those having a porosity of 30 to 80% made of polypropylene or the like are preferable, and specifically, the porous plastic is, for example, manufactured by Kaken Co., Ltd. There is "filterlen" (product name), etc.

Reference numeral 22 denotes an electrode / porous plate support member used in the present embodiment.
23, an electrode mounting portion 24 having a diameter larger than that of the fixed portion 23 and for mounting the external electrode 14, and an air-impermeable and annular shield plate 25 that covers the back surfaces of the fixed portion 23 and the electrode mounting portion 24. . The porous plate 21 is fixed to the front surfaces of the fixing portion 23 and the electrode mounting portion 24 by means such as adhesion or screwing, and an annular air chamber 26 is defined in the electrode / porous plate supporting member 22. Has been done.

27 is an air supply pipe, and the air supply pipe 27 is provided at the base end side of the air supply pipe 28.
And the tip side is connected to the air supply hole 25A of the shielding plate 25 so that air can be supplied from the air source 28 into the air chamber 26.

The electrostatic coating apparatus according to this embodiment is configured in this way, and its operation will be described next.

When the external electrode 14 is connected to the high-voltage generator 15 to be charged and a corona discharge region is formed, the paint is supplied to the rotary atomizing head 10 and the rotary atomizing head 10 is driven to rotate, whereby paint particles are generated. After passing through the corona discharge region after atomization, there is no particular difference from the prior art in that electrostatic coating is performed by electrostatically charging and flying-coating the article 17 to be coated.

Therefore, in the present embodiment, the air from the air source 28 is pressure-fed into the air chamber 26 from the shielding plate 25 via the air supply pipe 27,
The internal pressure of the air chamber 26 is increased. As a result, the air chamber 26
The air supplied into the inside of the porous plate 21 passes through the continuous bubbles to form a uniformly dispersed air flow K ₁ in the circumferential direction from the front side of the porous plate 21, covering the entire outer peripheral surface of the front end side 3A of the cover 3. .

Therefore, the airflow X based on the rotation of the rotary atomizing head 10 is generated,
Even if airflows Y and Y ′ are generated due to the air pumping phenomenon, the cover 3 covers the entire outer peripheral surface of the front end side 3A by the airflow K ₁
Since it is covered with, the airflows Y and Y ′ are positively blocked from flowing toward the cover 3 and the external electrode 14.
As a result, even if there are paint particles floating due to the air flow X, they are prevented from being caught in the air flows Y and Y ′ due to the air pumping phenomenon and being applied to the cover 3 as in the prior art, and the external electrode 14 Even if there is a potential difference between the charged paint particles and the charged paint particles, the charged paint particles can be prevented from adhering to the external electrode 14, and the cover 3 and the external electrode 14 can be kept in a clean state. In addition, the support member 22 that supports the porous plate 21 serves both as a support for the external electrode 14 and a support for the porous plate 21, and as the support member 22, a conventional electrode support member 11 can be used. The implementation of the example can be carried out very easily.

In the above embodiment, the external electrode 14 is used when coating the water-based and metallic paints,
The present invention is not limited to this, and the external electrode 14 may be used when solvent-based paint is applied.

[Effect of the Invention] As described above, according to the present invention, an air chamber is provided in the external electrode supporting member provided on the cover to support the external electrode, and the air from the air chamber is supplied to the supporting member. A configuration is provided in which a porous plate that blows out to the front end side of the cover is provided, and air is uniformly blown to the outer circumference of the front end side of the cover by supplying air to the air chamber, and the entire outer circumference of the front end side of the cover is covered by the air flow of the air. So, out of the paint particles,
It is possible to positively push the flow of the paint particles toward the cover and the external electrode forward, and prevent the paint particles from coating the cover and the external electrode. Then, the cover and the external electrode can be kept clean, and the coating state can be improved. Furthermore, the present invention can be easily implemented by providing a porous member on a support member that supports a conventional external electrode.

[Brief description of drawings]

1 and 2 show an embodiment of the present invention, and FIG. 1 is a side view in which a part of the front end side of the electrostatic coating apparatus equipped with the porous plate of this embodiment is shown in section. Is a perspective view of the porous plate,
FIG. 3 is a side view of a state in which the front end side of the conventional electrostatic coating device is partially sectioned. 1 ... Coating device main body, 2 ... Air motor, 3 ... Cover, 9 ... Rotating shaft, 10 ... Rotating atomizing head, 14 ... External electrode, 21 ... Porous plate, 22 ... Support member, 26 …… Air chamber,
K ₁ ... airflow.

Claims (1)

[Scope of utility model registration request] 1. A cylindrical coating apparatus main body having an air motor for driving a rotary shaft therein, a cover for covering at least the front end side of the coating apparatus main body, and a rotary shaft positioned at the front end side of the coating apparatus main body. A rotary atomizing head that is attached and rotationally atomizes the selected paint by selectively supplying any of water-based paint, metallic paint and solvent-based paint,
An external electrode supporting member provided on the cover at a position radially outward of the rotary atomizing head, and the paint particles supported by the supporting member and atomized by the rotary atomizing head are charged to be covered. In an electrostatic coating device consisting of an external electrode for flight coating toward a coated object, an air chamber is provided in the support member,
The support member is provided with a porous plate that blows air from the air chamber to the front end side of the cover, and air is blown through the porous plate by supplying air to the air chamber,
An electrostatic coating device, characterized in that the outer periphery of the front end side of the cover is covered with an air flow to prevent the coating particles from being applied to the cover and external electrodes.