JP3078690B2 - Electrostatic coating machine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrostatic spraying machine for electrostatically atomizing paint supplied from a paint pipe inserted into a tubular rotary shaft, and more particularly to an electrostatic sprayer suitable for electrostatically coating metallic paint. To an electrostatic coating machine.

[0002]

2. Description of the Related Art A rotating atomizing head to which a high voltage is applied is rotated at a high speed to atomize the paint by its rotating force and electrostatic force, and at the same time, paint is electrostatically applied to a work applied to the opposite pole. Electrostatic coatings that are made to be applied not only have high coating efficiency and low waste of paint, but also can form a uniform coating film. It is used for painting.

[0003] When a metallic paint is applied by a rotary atomizing type electrostatic coating machine, a foil-like metal piece contained in the metallic paint is polarized by electrostatic action, and it is as if planted hair on the work surface. Thus, the coating film is applied in a certain direction as described above, so that the coating film exhibits an iridescent color whose color changes depending on the viewing direction, or a stripe pattern emerges depending on the condition of the light beam.

For this reason, in the case of performing metallic coating, conventionally, an air atomizing type electrostatic coating machine having a relatively weak electrostatic action has been used, or an air spray gun which does not use any electrostatic action has conventionally been used. However, the coating efficiency when using these coating machines is at most 40 to 50% even for an air atomizing type electrostatic coating machine, and 30% for an air spray gun.
Not only is there a lot of waste of paint compared to a rotary atomization type electrostatic coating machine which has extremely low coating efficiency of 80% or more,
There has been a problem that exhaust processing when exhausting contaminated air containing paint mist that has not adhered to the work is costly.

[0005] For this reason, the present inventors have proposed that in a rotary atomizing type electrostatic coating machine, if the stirring air can be jetted from the inside of the paint spray slit formed in the rotary atomizing head, the paint inside It was thought that the direction of the metal pieces contained in the mixture was uneven due to agitation, and an attempt was made to inject shaping air from the outside of the paint spray slit and to inject agitation air from the inside. In this case, in a so-called side-feed type electrostatic coating machine in which the paint pipe is disposed at a position eccentric from the rotation axis of the air motor, the rotation shaft of the air motor is formed in a tubular shape, and the opening at the tip is formed inside the paint spray slit. The agitating air can be supplied to the air injection slit with a simple structure by communicating with the air injection slit formed in the above.

[0006]

However, in the side-feed type electrostatic coating machine, an annular slit or opening is formed so that a paint pipe can be inserted from the back side of the rotary atomizing head. When the paint is supplied to the rotating atomizing head, there is a problem that the paint rebounds and splatters on the back side of the rotating atomizing head, or the paint is charged without being atomized and adheres to the workpiece. . For this reason, in recent years, a center feed type electrostatic coating machine that supplies paint from a paint pipe inserted through a tubular rotary shaft of an air motor so that the supplied paint does not scatter from the back side of the rotary atomizing head has become popular. However, in this type of electrostatic coating machine, it is extremely difficult to supply compressed air for stirring from the tubular rotary shaft because the paint pipe is inserted into the tubular rotary shaft.

[0007] That is, when an attempt is made to supply stirring air to the air jet slit formed along the inside of the paint spray slit via a tubular rotary shaft similarly to a side-feed type electrostatic coating machine, the structure is increased. There is a problem in that it becomes very complicated and the production cost increases. Therefore, the present invention provides a simple structure for reliably stirring air with a simple structure in an air jet slit formed along the inside of a paint spray slit, even when applying a metallic paint with a center feed type electrostatic coating machine. It is an object of the present invention to provide a coating film that does not exhibit an iridescent color or a stripe pattern.

[0008]

SUMMARY OF THE INVENTION In order to solve this problem, the present invention provides a rotary atomizing head attached to the tip of a tubular rotary shaft of an air motor, which is built into the body with its tip face exposed, The paint supplied into the rotary atomizing head from the paint pipe inserted into the tubular rotary shaft is atomized from a paint spray slit formed at the peripheral edge of the tip of the rotary atomizing head. In an electrostatic coating machine configured to suppress the spread of spray paint by injecting shaping air from the outside, a positive pressure chamber receiving a supply of compressed air is provided inside the machine, on the rear side of the rotary atomizing head. Is formed on the rotary atomizing head, along the inside of the paint spray slit,
An air injection slit for injecting air for agitating the spray paint is formed in an annular shape, and an air flow path for supplying air in the positive pressure chamber to the air injection slit is provided on the rear or side surface of the rotary atomizing head. And a hole is formed in the positive pressure chamber.

[0009]

According to the present invention, first, the paint supplied through the inside of the tubular rotary shaft of the rotary atomizing head is atomized by the rotation of the rotary atomizing head and the electrostatic force, and formed on the peripheral edge of the tip. Spreading is suppressed by shaping air injected from the outside of the paint spray slit and sprayed in a predetermined pattern.
At this time, the air injection slit formed along the inside of the paint spray slit and the positive pressure chamber formed on the back side of the rotary atomizing head are formed through the rear or side of the rotary atomizing head. High-pressure air in the positive pressure chamber is injected from the air injection slit through the air flow path, and the air flow is swirled outward by the rotation of the rotary atomizing head. It is injected as a flow.

Therefore, when a metallic paint is applied, the paint sprayed from the paint spray slit is maintained in a predetermined spray pattern by being surrounded by shaping air, and has a spiral shape formed inside the paint. Stirred by the air flow, the direction of the metal pieces contained in the paint becomes uneven, so a uniform metallic coating film is formed,
In addition, since the paint component is applied to the work surface by the electrostatic force, the application efficiency does not decrease.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be specifically described below based on embodiments shown in the drawings. FIG. 1 is a sectional view showing an embodiment of the present invention, and FIG. 2 is an enlarged front view showing a main part thereof.

In FIG. 1, reference numeral 1 denotes an electrostatic coating machine in which a rotary atomizing head 2 to which a high voltage is applied is attached to a tip of a tubular rotary shaft 4 of an air motor 3. A paint spray slit 6 is built in the body 5 with its surface exposed, and a paint spray slit 6 for spraying paint supplied through the inside of the tubular rotary shaft 4 by electrostatic atomization is formed in the peripheral edge of the body. Have been.

The rotary atomizing head 2 has therein a paint chamber 7 communicating with the opening of the tip of the paint pipe 4a inserted through the tubular rotary shaft 4, and the paint chamber 7 is formed radially. The paint spray slit 6 through the paint passage 7a
Is communicated to. Along the inside of the paint spray slit 6, an air jet slit 9 for spraying the air for spray paint agitation is formed in an annular shape, and the slit 9 is an air chamber formed in the rotary atomizing head 2. 10 is communicated. Each of the slits 6, 9 is formed by arranging a large number of slots 6a, 9a at predetermined intervals in a ring shape so that the slit width is not biased. It may be.

A positive pressure chamber 5a, which is supplied with compressed air by a compressed air supply pipe 12, is formed on the rear side of the rotary atomizing head 2 in the machine body 5. An air flow path 11 for supplying the air in the positive pressure chamber 5a to the air chamber 10
Penetrates the side surface of the rotary atomizing head 2 and the paint passage 7
The positive pressure chamber 5a is bored between the holes a and 7a. The air flow path 11 is formed equiangularly about the tubular rotary shaft 4 so that the center of gravity of the rotary atomizing head 2 coincides with the center of rotation.

The compressed air supplied to the positive pressure chamber 5a is injected as shaping air from a gap 8 formed between the body 5 and the rotary atomizing head 2, and is also discharged through the air flow path 11. The air is supplied to the air chamber 10 and is injected from the air injection slit 9 as air for stirring.

The above is an example of the configuration of the present invention, and its operation will now be described. First, the rotary atomization head 2 is rotated while applying a high voltage to the compressed air supply pipe 1.
2 to supply compressed air into the positive pressure chamber 5a.
When the metallic paint is supplied from, the paint reaches the tip of the paint spray slit 6 from the paint chamber 7 through the paint passage 7a, and is atomized by its rotational force and electrostatic force.

At this time, the compressed air supplied into the positive pressure chamber 5a is injected as shaping air from a gap 8 formed between the machine body 5 and the rotary atomizing head 2, and the stirring air is also supplied. Is injected from the air injection slit 9. Therefore, compressed air is sprayed from both the outside and the inside of the paint spray slit 6, and the paint is atomized not only by the rotational force and the electrostatic force but also by the air pressure. Also, the paint can be atomized and sprayed, and coating defects due to deformation of the metal piece due to high-speed rotation of the rotary atomizing head 2 can be prevented.

The atomized paint is sprayed in a predetermined pattern while the spread due to centrifugal force is suppressed because the shaping air is sprayed to the outside, and the paint is sprayed from the air spray slit 9 on the inside. The sprayed air flow becomes a vortex and the sprayed paint is stirred. Therefore, even if the metal pieces contained in the paint are polarized and oriented in a certain direction, the directions are not uniform due to the agitation caused by the vortex, and the metal pieces electrically affect each other, and the polarities of each other are changed. Cancel each other out. Then, the paint component in the paint is electrostatically applied as it is, and the metal pieces are applied in an irregular direction, so that a coating film in which the metal pieces are uniformly dispersed in the coating film is formed, and at the same time, the coating is performed. There is no decrease in the wearing efficiency.

FIG. 3 is a cross-sectional view showing another embodiment of the present invention, FIG. 4 is a cross-sectional view showing an enlarged main portion, FIG. 5 is a front view thereof, and FIG. FIG. 2 is an enlarged cross-sectional view showing a main part of FIG. The same reference numerals are given to the same parts as those in FIG. 1, and the detailed description is omitted.

In this embodiment, the compressed air supplied into the positive pressure chamber 5a is used only as stirring air, and a shaping air supply means is separately provided so that the compressed air in the machine body 5 does not leak from the gap 8 to the outside. In addition, the width of the gap 8 is selected to be small, and a concave portion 15 is formed on the outer peripheral surface of the rotary atomizing head 2 to prevent the flow of the air flowing through the gap 8. The recess 15 is formed by engraving a groove 16 so that a plurality of flanges 17 are formed along the circumference as shown in FIG.
As shown in (1), one or a plurality of spiral grooves 18 may be engraved.

Further, a shaping air injection slit 19 is formed in the body 5 along the outer periphery of the rotary atomizing head 2 in a ring shape, and a compressed air supply pipe 20 is connected to the slit 19, and is not shown. However, each compressed air supply pipe 1
The pressure of the shaping air and the pressure of the stirring air can be set individually by regulators and the like interposed in 2, 20. The shaping air injection slit 19 is formed by arranging a large number of slots 19a in an annular shape so that the slit width is uniform without unevenness. It may be.

When the coating is started, the compressed air supplied from the compressed air supply pipe 20 is sprayed in a predetermined pattern by the shaping air injected from the shaping air injection slit 19, and at the same time, the paint is sprayed into the positive pressure chamber 5a. Is sprayed from the air jet slit 9 to form a vortex, which stirs the sprayed paint. At this time, the pressure of the shaping air and the pressure of the stirring air can be set individually, so while observing the spray state,
According to various kinds of external factors such as the type of the paint and the temperature and the humidity, it is possible to arbitrarily set the pressure in the best paint state. A concave portion 15 is formed on the outer peripheral surface of the rotary atomizing head 2. When air flows into the gap 8 between the body 5 and the rotary atomizing head 2, a pressure difference is generated depending on the location of the gap 8. Is difficult to flow, and air hardly leaks outside through the gap 8.

[0023]

As described above, according to the present invention, when a metallic paint is applied by electrostatic atomization by rotation of a rotary atomizing head and electrostatic force, the outside of the spray paint is regulated by shaping air. At the same time, the metallic pieces in the paint that have been polarized by the electrostatic force and oriented in a uniform direction are agitated by the vortex of the stirring air formed inside the spray paint, and the orientation is uneven, so that the iridescent color is changed. It is possible to form a uniform metallic coating film without exhibiting or embossing stripes, and the coating component has an excellent effect of being efficiently applied to the surface of the object by electrostatic force. In addition, since the stirring air is supplied through an air flow passage penetrating the back or side of the rotary atomizing head, the structure is simple and the manufacturing cost is low,
There is an effect that the existing electrostatic coating machine can be improved only by replacing the rotary atomizing head.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an embodiment of the present invention.

FIG. 2 is an enlarged front view showing a main part thereof.

FIG. 3 is a sectional view showing another embodiment.

FIG. 4 is an enlarged sectional view showing a main part thereof.

FIG. 5 is a front view thereof.

FIG. 6 is an enlarged sectional view showing a main part of still another embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Electrostatic coating machine 2 ... Rotation atomization head 3 ... Air motor 4 ... Tube rotary shaft 4a ... Paint pipe 5 ... Machine 5a ... Positive pressure chamber 6 ... Paint spray Slit 8 ... Gap 9 ... Air injection slit 11 ... Air flow path

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-2-152568 (JP, A) JP-A-62-140660 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) B05D 5/04

Claims (1)

(57) [Claims] 1. A rotary atomizing head (2) attached to a distal end of a tubular rotary shaft (4) of an air motor (3) is incorporated in an airframe (5) with its distal end surface exposed, and said tubular rotary shaft is provided. The paint supplied from the paint pipe (4a) inserted into (4) into the rotary atomizing head (2) is supplied from the paint spray slit (6) formed on the peripheral edge of the tip of the rotary atomizing head (2). In the electrostatic coating machine which is atomized and suppresses the spread of the spray paint by spraying shaping air from the outside of the rotary atomizing head (2), the rotating body (5) includes the rotating machine. A positive pressure chamber (5a) receiving a supply of compressed air is formed on the back side of the atomizing head (2), and the rotary atomizing head (2) is provided along the inside of the paint spray slit (6). An air jet slit (9) for jetting air for stirring the spray paint is formed in an annular shape. An air flow path (11) for supplying air in the positive pressure chamber (5a) to the air injection slit (9) penetrates the back or side of the rotary atomizing head (2). (5a) An electrostatic coating machine having an opening formed therein.