JPS59213461A - Electrostatic coating apparatus - Google Patents

Abstract

PURPOSE:The amt. of compressed air to be fed to an electrostatic coating apparatus is remarkably reduced by forming an approximately annular air passage to the front end of a case body and introducing compressed air from an air-motor to the case body into said air passage. CONSTITUTION:An end of a pipe conduit 20 consisting of a pipe 21 formed by bending to approximately L-shape as a whole is opened to the inside of a case body 1 enclosing an air-motor 2 and fixed to the side wall of the case body 1, and another end is connected to the front end side of the case body 1, i.e. to the air passage 13 formed at the side end part of a cup-shaped body 4. By this constitution, the compressed air which has been conventionally exhausted to the outside is utilized as shaping air, therefore, the consumption of compressed air is remarkably saved.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an electrostatic coating device in which a coating agent is supplied to a cup-shaped body that is driven to rotate at high speed by an air motor, and is atomized by centrifugal force and electrostatic force and then radiated.

Conventionally, this type of electrostatic coating apparatus has been constructed as shown in FIG. A cup-shaped body 4 is fixed to the tip thereof.

The cup-shaped body 4 is integrally formed with a substantially cylindrical outer cylinder 5, a partition wall 6 that closes the axial center of the outer cylinder 5, and the center of the partition wall 6, and the diameter gradually increases toward the partition wall 6. It is composed of a truncated conical inner cylinder 7, a partition wall 6 and an outer cylinder 5.
A slit 8 is formed at a required interval between them, and a high voltage of about 80 to 120 KV is applied, although not shown.

9 is a rust preventive oil applied to the back surface of the partition wall 6 of the cup-shaped body 4;

A coating agent supply pipe that supplies a coating agent such as paint,
It is fitted into a coating agent passage 10 formed at the front end of the case body 1. The coating agent passage 10 opens on the side surface of the case body 1 and is connected to a coating agent supply source (not shown) via a nipple 11 and a hose 12.

The object to be coated 17, such as a plate-like object, is conveyed at a required speed.
radiated to.

At this time, compressed air is blown out from the front end surface of the case body 1 through a large number of small holes or slits 16 made in the air passage 13, and an air flow called shaving air is formed. The coating agent particles emitted from the cup-shaped body 4 are electrostatically applied to the object 17 with a uniform coating distribution due to the flow.

As mentioned above (in the conventional device, the cup-shaped body 4 is
Air motor 2 that rotates at a high speed of about 0.00 Orpm
In order to rotate the air motor 2, approximately 2 to 4
In addition to feeding several hundred liters of compressed air per minute, approximately 0.4 to 1.2 kg is also supplied to the air passage 13 in order to uniformize the coating distribution with shaving air.
Compressed air of the order of /cnl is also fed several hundred liters per minute.

Therefore, for one electrostatic coating device, the compressed air for driving the air motor rotation and the compressed air for shaving air, for example, a total of 60'OR/m1n13, are supplied to the annular shape formed at the front end of the case body 1. The air passage is connected to a compressed air supply source (not shown) such as a compressor separately disposed through a nipple 14 and a hose 15 disposed on the side surface of the case body 1, and is connected to a compressed air supply source (not shown) such as a separately disposed compressor. A large number of small holes or slits 16 are formed on the front surface of the case body 1 facing the cup-shaped body 4 to allow compressed air supplied from the source.
The shaving air is ejected forward through the cup-shaped body 4 to form an air flow called shaving air along the outer surface of the cup-shaped body 4.

Then, the air motor 2 moves the can and the plastic body 4 for about 20 minutes.
．． When the coating agent is rotated at a high speed of about 000 rpm and in this state is dripped and supplied to the back surface of the partition wall 6 through the coating agent supply pipe 9, the coating agent passes from the back surface of the partition wall 6 through the slit 8 due to centrifugal force to the inner circumferential surface of the outer cylinder 5. Then, it is further supplied in the form of a thin film to the front end surface along the inner circumferential surface of the outer cylinder 5.

While a high voltage of 80 to 120 KV is applied to the cup-shaped body 4, if the coating agent supplied in a thin film form to the front end surface of the outer cylinder 5 needs to be misted due to electrostatic force, electrostatic coating When five devices are installed, it is necessary to supply compressed air at a rate of 3,000 J/min, which poses a problem in that the capacity of the compressor used for this becomes extremely large.

Therefore, the inventor of the present invention focused on the compressed air for the air motor, which was conventionally discharged to the outside through the silencer 18, etc., and came up with the idea of using this as compressed air for shaving air. It is an object of the present invention to provide an electrostatic coating device that can significantly reduce the supply amount compared to conventional devices.

To this end, the present invention supplies a coating agent to a cup-shaped body that is connected to an air motor disposed inside the case body, is driven to rotate at high speed, and is applied with a high voltage, and the coating agent is applied by centrifugal force and electrostatic force. An electrostatic coating device that atomizes and radiates particles, wherein a substantially annular air passage is formed at the front end of the case body, and a large number of small holes are formed on the surface of the air passage facing the cup-shaped body. Alternatively, in the electrostatic coating device in which a slit is formed, a pipe line is provided for introducing compressed air discharged from the air motor into the case body into the air passage.

Hereinafter, the present invention will be explained based on embodiments shown in the drawings.

FIG. 2 is a cross-sectional view showing an example of an electrostatic coating device according to the present invention.
The structure is substantially the same as that shown in FIG. 1, except that it has a conduit 2o connected to the pipe line 2o, and a detailed explanation of the common parts will be omitted.

The conduit 20 is composed of a pipe 21 bent into an abbreviated shape as a whole, and one end of the pipe 21 is connected to the air motor 2.
It is opened in the case body 1 containing a built-in case body 1 and is fixed to the side wall of the case body 1, and the other end is connected to the air passage 13 formed on the front end side of the case body 1, that is, the end on the side of the cup-shaped body 4. ing.

A needle valve 24 consisting of a valve body 22 and an operator 23 is disposed inside the pipe 21 at the bent portion of the conduit 20 .

When a compressed air supply pipe (not shown) is connected to the connection joint 25 and compressed air at a required pressure is supplied into the air motor 2, the air motor 2 is rotated at high speed by the compressed air, and its A cup-shaped body 4 connected to the tip of the rotating shaft 3 is driven to rotate at high speed.

At this time, after the air motor 2 is rotated, the air pressure inside the case body 1 increases due to the compressed air discharged as exhaust from the exhaust holes 26, 26-, which are bored in the outer peripheral wall of the air motor 2. The opening of the pipe 21 fixed to the side wall of the body 1 is introduced into the substantially annular air passage 13 through the oval-shaped conduit 20, which is formed on the side of the cup-shaped body 4 of the air passage 13. Many small holes or slits 1
6 along the outer surface of the cup-shaped body 4;
It is ejected as air.

As described above, according to the present invention, the exhaust air from the air motor 2 can be used as shaving air, so the capacity of the compressor used in the electrostatic coating device can be extremely small compared to conventional devices. This has an excellent effect.

Note that even if there is some pressure loss in the compressed air discharged into the case body 1 from the exhaust hole 26 of the air motor 2, the air pressure of the compressed air supplied to the air motor 2 is normally 2 to 4 kg/c+J. On the other hand, the air pressure of the compressed air supplied to the air passageway 3 as shaving air is relatively low, 0.4 to 1.2 kg/cd, so it can be used sufficiently as shaving air. be.

In addition, if the air pressure of the compressed air discharged from the air motor 2 into the case body 1 is too high, the needle valve 2
By appropriately adjusting the flow rate of air introduced into the airway 13 from inside the case body 1 and exhausting excess air to the outside, a desired amount of shaving air can be obtained.

In this case, the cup-shaped body 4 has a voltage of 80 to 120 KV.
Since a relatively high voltage is applied and it is dangerous to approach the non-electric current, the operator 23 that adjusts the opening and closing of the valve body 22 of the needle valve 24 is extended to the rear end of the case l as shown in the figure. It's a good idea to let them do it.

Note that when using an air turbine type ultra-high-speed rotary air motor that uses air bearings as an air motor, compressed air for the bearings is also supplied in addition to the compressed air for rotation, but in the present invention, compressed air for the bearings is also supplied. It goes without saying that the compressed air discharged from the bearing may be used as kneeping air.

As described above, according to the present invention, a conduit is provided that leads from the case body containing the air motor to an air passageway in which a large number of small holes or slits are formed for blowing out shaving air. The conduit allows the compressed air discharged into the case from the air motor to be used as shaving air, which would otherwise be discharged directly to the outside as exhaust air, thus reducing the amount of compressed air supplied to the electrostatic coating device. This has the effect of making it possible to significantly reduce the amount of energy used, resulting in energy savings.

[Brief explanation of the drawing]

FIG. 1 is a partially sectional front view showing a conventional electrostatic coating apparatus, and FIG. 2 is a partially sectional front view showing an electrostatic coating apparatus according to the present invention. Explanation of symbols 1-case body, 2-air motor, 3-rotating shaft of air motor, 4-cup-shaped body, 13-air passage, 16-.
Small hole or slit, 20--duct. Patent applicant Trinity Industries Co., Ltd.

Claims (1)

[Claims] A coating agent is supplied to a cup-shaped body that is connected to an air motor disposed inside the case body, driven to rotate at high speed, and to which a high voltage is applied, and the coating agent is atomized by centrifugal force and electrostatic force and released. An electrostatic coating device comprising:
In the electrostatic coating device, a substantially annular air passage is formed in the front end of the case body, and a large number of small holes or slits are formed in the surface of the air passage facing the cup-shaped body, from the air motor to the An electrostatic coating device characterized in that a conduit is provided for introducing compressed air discharged into the case body into the air passage.