JP3753646B2 - Rotary atomizing coating equipment - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a rotary atomizing coating apparatus that atomizes and discharges paint from a rotary atomizing head to an object to be coated.
[0002]
[Prior art]
For example, when spraying an object to be coated such as an automobile body, a rotary atomizing coating apparatus is widely used. This rotary atomizing coating apparatus generally includes a rotary atomizing head that is rotated via an air turbine (or an air motor), and a shaping air ring that is attached so as to surround the rotary atomizing head. Then, by spraying the shaping air from the outlet formed in the shaping air ring toward the outer periphery of the tip of the rotary atomizing head, the paint sprayed from the rotary atomizing head is formed into a predetermined application pattern. It is comprised so that it may apply to a to-be-coated object.
[0003]
By the way, this type of rotary atomizing coating apparatus has a problem that paint mist adheres to the shaping air ring and gets dirty, and a problem that paint application efficiency is low and paint is wasteful. Various proposals have been made for this purpose.
[0004]
For example, in a “rotating atomizing head type coating apparatus” disclosed in Japanese Patent Application Laid-Open No. 8-332418 (hereinafter referred to as Prior Art 1), a coating machine body whose outer peripheral side is covered with a resin cover, and the coating machine body An air motor that is provided at a ground potential, a rotary atomizing head that is positioned on the front end side of the coating machine main body and is rotatable by the air motor, the front end of which is a paint discharge edge; and Shaping which is provided on the front end side of the coating machine body so as to cover the outer peripheral side of the rotary atomizing head located behind the coating discharge edge of the rotary atomizing head, and ejects shaping air from the air outlet An air ring, and an external electrode provided on the radially outer side of the main body of the coating machine and applied with a high voltage from the outside to charge the paint particles sprayed from the paint discharge edge of the rotary atomizing head. Rotating atomizing head type In instrumentation device, at least part of said shaping air ring, the formed by the air motor and electrically conductive material which is connected, at least some portions made of conductive material are formed as an annular repulsion electrode.
[0005]
Further, in the “rotary electrode type electrostatic coating gun” disclosed in Japanese Patent Publication No. 4-10383 (hereinafter referred to as “prior art 2”), the inner peripheral surface of the gun body gradually increases in diameter toward the tip edge. A cylindrical rotating electrode is installed to form a high-potential electrostatic field between the rotating object and the liquid paint supplied to the inner peripheral surface of the rotating electrode by the rotation of the rotating electrode. In a rotating electrode type electrostatic coating gun that is atomized and released by the action of an electrostatic field and is applied to an object by electrostatic attraction, a cylindrical body surrounding the outer periphery of the rotating electrode is provided on the gun body. By providing a gap between the rotating electrode and the rotating electrode, an annular air passage is formed between the cylindrical body and the rotating electrode, and a pressurized air supply port faces the middle of the air passage. In addition, a communication hole communicating with the atmosphere is provided on the rear end side of the air passage, By discharging pressurized air from the pressurized air supply port, air is sucked into the air passage from the communication hole, and is ejected together with the pressurized air from the tip of the air passage as an annular air flow. ing.
[0006]
[Problems to be solved by the invention]
However, when performing metallic coating, in the above-described prior art 1, there is a possibility that metallic flakes in the paint are applied in a state where they are not arranged in a certain direction with respect to the object to be coated. For this reason, in particular, the color tone of light colors tends to deteriorate, and paint adjustment (toning) is required before painting. As a result, in the case of using multiple colors, it is pointed out that it is not economical because it requires adjustment of paint for the number of colors and a rotary atomizing type coating apparatus for the number of colors.
[0007]
Further, in the above-described prior art 2, it is not specified from which direction the plurality of pressurized air supply ports blow the shaping air on the outer peripheral surface of the rotating electrode, and the mounting to the rotating electrode is not specified. There is no provision for location. Therefore, it has been pointed out that it is difficult to obtain the lightness of the light color tone of the metallic paint, and a stable coating pattern cannot be formed.
[0008]
Therefore, a configuration for forcibly applying the paint to the object to be coated via air pressure is conceivable, but since the air pressure is set high, the paint easily collides with the object to be coated and is scattered. There is a problem that a large amount of paint is wasted.
[0009]
The present invention solves this type of problem, and with a simple configuration, it is possible to stabilize the lightness of light colors, and it is possible to reliably obtain a desired coating pattern without requiring paint toning. An object is to provide a rotary atomizing coating apparatus.
[0010]
[Means for Solving the Problems]
In the rotary atomization type coating apparatus according to the present invention, the rotary atomization head for atomizing the paint, and the rotary atomization head arranged behind the front end of the rotary atomization head to surround the rotary atomization head, An outer shaping air ring having a flat shape surface inclined radially outward at the front end side and a diffuser shape portion having an arc shape surface at the rear end side, and the outer shaping air ring covered with the outer shaping air ring. And an inner shaping air ring that forms a jet port with the air ring.
[0011]
And the product D × N of the diameter D (mm) of the rotary atomizing head and the rotational speed N (rpm) of the rotary atomizing head is set within the range of 1,500,000 to 2,500,000. In addition, the flow rate of the shaping air ejected from the ejection port is set within a range of 450 to 700 (Nl / min) (air 0 ° C., 1 atm).
[0012]
The spout has an inclined cylindrical space portion that ejects shaping air to the outer peripheral surface of the tip side of the rotary atomizing head along the air discharge side inclined surface of the outer shaping air ring. Further, a virtual intersection point of a first imaginary line extending along the plane direction of the flat shape surface of the outer shaping air ring and a second imaginary line extending along the air ejection side inclined surface is provided, and the virtual intersection point And the shortest distance from the tip surface of the rotary atomizing head to the virtual reference line when providing a virtual reference line and a virtual tip line parallel to the tip surface of the rotary atomizing head from the tip position of the inclined cylindrical space portion, respectively. S1 and the shortest distance S2 from the virtual tip line to the virtual reference line are set within a range of shortest distance S1: shortest distance S2 = 1: 1.1 to 1.6.
[0013]
Thereby, a coating material can be efficiently and rapidly made to adhere with respect to a to-be-coated object. In particular, when metallic coating is performed, the metallic flakes in the paint are arranged in a certain direction, so that it is possible to stabilize the lightness of the light-colored color without the need for toning of the paint, and a predetermined coating pattern. You can definitely get it.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 is a schematic diagram illustrating a main part of a rotary atomizing coating apparatus 10 according to an embodiment of the present invention.
[0015]
The rotary atomizing coating apparatus 10 includes a casing 12 in which an air turbine 14 and the like are installed, and a rotary atomizing head 18 is mounted on a rotary shaft 16 of the air turbine 14. An outer shaping air ring 20 is screwed to the tip of the casing 12. An inner shaping air ring 22 is attached so as to be covered by the outer shaping air ring 20, and a jet port 24 for ejecting the shaping air is formed between the outer shaping air ring 20 and the inner shaping air ring 22. The
[0016]
The outer peripheral surface 26 on the front end side of the rotary atomizing head 18 has a conical shape that inclines radially outward (in the direction of arrow Y) toward the front end surface A of the rotary atomizing head 18. The distal end position of the outer shaping air ring 20 is disposed rearward (in the direction of the arrow X) from the distal end surface A of the rotary atomizing head 18, and the diffuser-shaped portion 28 is disposed on the inner surface side of the distal end of the outer shaping air ring 20. Is provided. The diffuser-shaped portion 28 has a flat-shaped surface 30 inclined radially outward on the front end side, and has an arc-shaped surface 32 on the rear end side, and an air ejection side inclined rearward of the arc-shaped surface 32. A surface 33 is provided.
[0017]
The inner shaping air ring 22 is formed with a supply passage 34 that extends substantially in the axial direction and supplies the shaping air. The supply passage 34 is provided between the outer shaping air ring 20 and the inner shaping air ring 22. It communicates with the spout 24 via a chamber 36 provided in the nozzle.
[0018]
As shown in FIG. 2, the jet outlet 24 has an inclined cylindrical space portion 38 that ejects shaping air to the distal outer peripheral surface 26 of the rotary atomizing head 18 along the air ejection side inclined surface 33 of the outer shaping air ring 20. Have.
[0019]
A virtual intersection 42 of a first imaginary line 40a extending along the plane direction of the flat shape surface 30 of the outer shaping air ring 20 and a second imaginary line 40b extending along the air ejection side inclined surface 33 is provided. When the virtual reference line P1 and the virtual tip line P2 parallel to the tip surface A of the rotary atomizing head 18 are provided from the virtual intersection 42 and the tip position of the inclined cylindrical space 38, respectively, The shortest distance S1 from the tip surface A to the virtual reference line P1 and the shortest distance S2 from the virtual tip line P2 to the virtual reference line P1 are the shortest distance S1: the shortest distance S2 = 1: 1.1 to 1. .6 in the range.
[0020]
Operation | movement of the rotary atomization type coating apparatus 10 comprised in this way is demonstrated below.
[0021]
First, as a coating condition of the rotary atomizing coating apparatus 10, the product D × N of the diameter D (for example, 30 mm to 50 mm) of the rotary atomizing head 18 and the rotational speed N (rpm) of the rotary atomizing head 18 is used. Is set within the range of 1,500,000 to 2,500,000, and the flow rate of the shaping air ejected from the ejection port 24 is 450 to 700 (Nl / min) (air 0 ° C. 1 atm). Set to range.
[0022]
Therefore, as shown in FIG. 1, the air turbine 14 is driven, the rotary atomizing head 18 attached to the rotary shaft 16 rotates, and the shaping air is supplied to the supply passage 34. This shaping air is sent from the supply passage 34 to the jet outlet 24 through the chamber 36, and jetted from the inclined cylindrical space portion 38 constituting the jet outlet 24 toward the outer peripheral surface 26 on the front end side of the rotary atomizing head 18. The For this reason, as shown in FIG. 3, the mist-like metallic paint 50 discharged | emitted from the rotary atomization head 18 is shape | molded by a predetermined application pattern via shaping air, and is apply | coated to the to-be-coated article W. FIG.
[0023]
In this case, in this embodiment, as shown in FIG. 2, the outer shaping air ring 20 disposed behind the front end surface A of the rotary atomizing head 18 has a flat surface 30 and an arc-shaped surface 32. A diffuser-shaped portion 28 is provided. Further, the inclined cylindrical space portion 38 ejects shaping air to the distal outer peripheral surface 26 of the rotary atomizing head 18 along the air ejection side inclined surface 33 of the outer shaping air ring 20, and The shortest distance S1 from the tip surface A to the virtual reference line P1 and the shortest distance S2 from the virtual tip line P2 of the inclined cylindrical space 38 to the virtual reference line P1 are the shortest distance S1: the shortest distance S2 = 1. It is set within the range of 1.1 to 1.6 (see FIG. 2).
[0024]
The product D × N of the diameter D (mm) of the rotary atomizing head 18 and the rotational speed N (rpm) of the rotary atomizing head 18 is in the range of 1,500,000 to 2,500,000. The flow rate of the shaping air that is set and ejected from the ejection port 24 is set within a range of 450 to 700 (Nl / min).
[0025]
As a result, as shown in FIG. 3, for example, the metallic paint 50 applied from the rotary atomizing head 18 is formed into a predetermined application pattern, and adheres efficiently and quickly to the workpiece W. Is done. At that time, since the metallic flakes 52 in the metallic paint 50 are arranged in a fixed direction with respect to the article W, the lightness of the light-colored color can be stabilized. Therefore, it is possible to obtain an effect that the toning of the metallic paint 50 is unnecessary and a desired application pattern can be obtained with certainty.
[0026]
By the way, various ratios of the shortest distance S1 from the tip surface A of the rotary atomizing head 18 to the virtual reference line P1 and the shortest distance S2 from the virtual tip line P2 of the inclined cylindrical space 38 to the virtual reference line P1 are variously changed. Then, an experiment was performed to detect a range in which the lightness index L ^* value is equal to or greater than the target value. The result is shown in FIG. This target value corresponds to a threshold value at which a stable light color can be obtained.
[0027]
Thereby, when the ratio between the shortest distance S1 and the shortest distance S2 is 1: 1.0 or less, and when the ratio is 1: 1.7 or more, the lightness index L ^* value includes a target value or less. A desired coating pattern could not be obtained stably. Accordingly, by setting the ratio of the shortest distance S1 and the shortest distance S2 within the range of 1: 1.1 to 1.6, it is possible to stabilize the lightness of light colors.
[0028]
【The invention's effect】
With the rotary atomizing coating apparatus according to the present invention, the paint can be efficiently and quickly attached to the object to be coated with a simple configuration. In particular, when metallic coating is performed, it is possible to arrange metallic flakes in a certain direction to stabilize the lightness of light colors, eliminate the need for paint toning, and reliably obtain a stable coating pattern. be able to.
[Brief description of the drawings]
FIG. 1 is an explanatory diagram of a schematic configuration of a main part of a rotary atomizing coating apparatus according to an embodiment of the present invention.
FIG. 2 is a partially enlarged explanatory view of the rotary atomizing coating apparatus.
FIG. 3 is an explanatory view showing a coating state by the rotary atomizing coating apparatus.
FIG. 4 is an explanatory diagram of a lightness index L ^* value when changing the ratio between the shortest distance S1 and the shortest distance S2.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 ... Rotary atomization type coating device 14 ... Air turbine 18 ... Rotary atomization head 20 ... Outer side shaping air ring 22 ... Inner side shaping air ring 24 ... Outlet 26 ... Front end side outer peripheral surface 28 ... Diffuser shape part 30 ... Flat shape surface 32 ... Arc-shaped surface 33 ... Air ejection side inclined surface 38 ... Inclined cylindrical space 40a, 40b ... Virtual line A ... Tip surface P1 ... Virtual reference line P2 ... Virtual tip line

Claims (1)

A rotary atomizing head for atomizing the paint;
The rotary atomizing head is arranged behind the front end portion of the rotary atomizing head to surround the rotary atomizing head, and has a flat shape surface inclined radially outward on the front end side and an arc-shaped surface on the rear end side. An outer shaping air ring provided with a diffuser-shaped part having,
An inner shaping air ring that is covered by the outer shaping air ring and forms a spout between the outer shaping air ring;
With
The product D × N of the diameter D (mm) of the rotary atomizing head and the rotational speed N (rpm) of the rotary atomizing head is set within a range of 1,500,000 to 2,500,000. ,And,
The flow rate of shaping air ejected from the ejection port is set within a range of 450 to 700 (Nl / min),
The spout has an inclined cylindrical space portion that ejects shaping air to the outer peripheral surface of the tip side of the rotary atomizing head along the air discharge side inclined surface of the outer shaping air ring, and
A virtual intersection point of a first imaginary line extending along the surface direction of the flat shape surface of the outer shaping air ring and a second imaginary line extending along the air ejection side inclined surface is provided, and the virtual When providing a virtual reference line and a virtual tip line parallel to the tip surface of the rotary atomizing head from the intersection and the tip position of the inclined cylindrical space portion, respectively, from the tip surface of the rotary atomizing head to the virtual reference line The shortest distance S1 and the shortest distance S2 from the virtual tip line to the virtual reference line are set within a range of shortest distance S1: shortest distance S2 = 1: 1.1 to 1.6. Rotating atomizing coating equipment.

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