JP4450344B2 - Air spray gun for painting - Google Patents

Description

【００１５】
図５から明らかなように、Ｇ、Ｆ、Ｂ、Ｃ、Ｅ、Ｈ、Ａ、Ｄ、標準の順に粒子径が小さくて溝９の無い標準より溝９のあるものは全て粒子径が小さく、総じて溝９の正面面積の総正面面積に対する割合が大きいもの程粒子径が小さいことが判明した。
【００１６】
しかしながら、Ｇ、Ｈのように溝９が深すぎて塗料経路まで切り込んだ場合には、ノズルの先端面に付着して溜まった塗料がエアーにより不規則に吹き飛ばされて被塗装物に塗着することにより、塗装不良の原因となるため好ましくない。
【図面の簡単な説明】
【図１】本発明の一実施の形態の断面図である。
【図２】その要部の拡大断面図である。
【図３】その塗料ノズルの先端部の正面図である。
【図４】各種の塗料ノズルの先端部の正面図である。
【図５】ノズルから噴出する塗料の粒子径を測定した結果を示すグラフである。
【符号の説明】
２：塗料ノズル
３：エアーキャップ
４：（塗料ノズルの）先端部
５：エアーノズル
９：溝[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an air spray gun for coating in which a liquid paint discharged from a nozzle is mixed with an air flow ejected from an air nozzle disposed at an outer periphery of the liquid paint to be atomized.
[0002]
[Prior art]
Since the outer periphery of the paint nozzle of a conventional paint air spray gun is circular, the air flow ejected from the air nozzle has a ring-shaped cross section, and the paint discharged from the paint nozzle is sucked into the air flow and mainly has an annular air flow. It was designed to mix with the air in the part close to the inner peripheral surface.
[0003]
[Problems to be solved by the invention]
For this reason, the contact area of the paint with the air is small, and a large amount of air is required to sufficiently mix and atomize the paint with the air, so that the amount of paint that scatters increases and the coating efficiency is low. There was a problem.
[0004]
[Means, actions and effects for solving the problems]
As means for solving such a problem, the present invention is such that an axial groove reaching the tip of the paint nozzle is formed on the outer periphery of the paint nozzle, and is ejected from the air nozzle. Since protrusions are formed on the inner peripheral surface of the air flow, and the protrusions are engulfed in the paint flow, the contact area between the paint and air is increased, and the atomization of the paint is promoted. To reduce the scattering and improve the coating efficiency.
[0005]
Furthermore, the present invention is such that the groove becomes deeper toward the tip of the paint nozzle, and since the air flow is blown obliquely into the paint flow, the paint is well mixed with the air and fine particles. Is further promoted, atomized with a smaller amount of air, less scattered, and coating efficiency is further improved. Further, the deeper the groove, the more the atomization is promoted. However, in the present invention, the groove notch does not reach the paint path at the tip of the paint nozzle. It can prevent adhering to the air cap surface. As a result, it is possible to prevent the coating failure that adheres to the surface of the object to be coated by the paint accumulated on the air cap surface being irregularly blown off by the air.
[0006]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.
In FIG. 1 showing the overall structure, reference numeral 1 denotes a gun body, and a paint nozzle 2 having a reduced inner and outer diameter of a tip portion 4 is fixed to the center of the gun body, and an air cap 3 surrounds the paint nozzle 2. Is fixed to the gun body 1.
[0007]
As shown in an enlarged view in FIG. 2, the air cap 5 is provided with an air nozzle 5 with an annular gap a between the tip end 4 of the paint nozzle 2 and the tip of the paint nozzle 2. By spraying pressurized air from the gap a around the paint discharged from the section 4, the paint is sucked into the pressurized air and mixed and atomized, as shown in FIG. The direction in which the mixed flow of paint and air is blown out is regulated by the pressurized air blown out from a large number of small holes 6 formed around the air nozzle 5 of the air cap 3, and further, protrudes up and down on the front of the air cap 3. The mixed flow of paint and air is flattened in a fan shape by the pressurized air blown out from the oblique holes 8 formed in the corner 7 provided.
[0008]
The above is the structure of the nozzle portion of a conventionally known air spray gun. This is because the outer peripheral surface of the tip portion 4 of the paint nozzle 2 is smooth, and the annular pressure that is ejected from the annular gap a. The inner surface of the air becomes smooth, the contact area with the sucked paint is small, the paint does not mix well with the pressurized air, and the paint is not sufficiently atomized. When the amount of pressurized air was increased, there was a problem that the coating efficiency was low because of easy scattering.
[0009]
Therefore, in the present embodiment, as shown in an enlarged view in FIGS. 2 and 3, the outer periphery of the tip portion 4 of the paint nozzle 2 has a triangular cross section and is cut obliquely so as to become deeper toward the tip. Ten axial grooves 9 are formed at equal angular intervals.
[0010]
For this reason, protrusions are formed on the inner peripheral surface of the air flow ejected from the air nozzle 5, and the protrusions bite into the paint flow, so that the contact area between the paint and air is increased and the paint is atomized. Is promoted, atomized with a small amount of air, less scattered, and the coating efficiency is improved.
[0011]
Further, since the groove 9 becomes deeper toward the tip of the paint nozzle 4 and the air flow is blown obliquely into the paint flow, the paint is well mixed with the air and atomization is further promoted. Since it is atomized with a small amount of air, it is less scattered and the coating efficiency is further improved.
[0012]
Here, using a constant pressure air atomizing spray gun having an inner diameter of the air nozzle 5 of 3.1 mm, an inner diameter of the paint nozzle of 1.6 mm, and an outer diameter of 2.6 mm, a spray distance: 300 mm, a discharge amount of 240 ml / min, atomization air pressure: 0.3 Mpa of standard paint nozzle 4 without groove 9 and 8 kinds of paint nozzles 4 having front faces A to H shown in FIG. The results of measuring the particle diameter of the paint sprayed from the nozzle 4 with a particle sizer while changing the viscosity are shown in Table 1, and the average value is shown in a graph in FIG.
[0013]
The maximum depth b of the groove 9 is 0.4 mm for A to F, 0.8 mm for G and H, the inclination angle α of the groove 9 is 30 °, and the front angle β of the groove 9 is A, B, G and H are 60 °, C and D are 30 °, E and F are 40 °, and only D is a trapezoid.
[0014]
[Table 1]

[0015]
As is clear from FIG. 5, the particle diameter is smaller in the order of G, F, B, C, E, H, A, D, and the standard, and all the grooves 9 are smaller than the standard without the groove 9. In general, it was found that the larger the ratio of the front area of the groove 9 to the total front area, the smaller the particle diameter.
[0016]
However, when the groove 9 is too deep and cut into the paint path as in G and H, the paint accumulated on the tip surface of the nozzle is irregularly blown off by the air and applied to the object to be coated. This is not preferable because it causes poor coating.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view of an embodiment of the present invention.
FIG. 2 is an enlarged cross-sectional view of the main part.
FIG. 3 is a front view of a tip portion of the paint nozzle.
FIG. 4 is a front view of the tip of various paint nozzles.
FIG. 5 is a graph showing the result of measuring the particle diameter of a paint ejected from a nozzle.
[Explanation of symbols]
2: Paint nozzle 3: Air cap 4: Tip (of paint nozzle) 5: Air nozzle 9: Groove

Claims (1)

An air nozzle is arranged with a ring-shaped gap around the outer periphery of the cylindrical paint nozzle, and the paint discharged from the paint nozzle is atomized by mixing with the annular air flow ejected from the air nozzle. In the air spray gun, an axial groove reaching the tip of the paint nozzle is formed on the outer periphery of the paint nozzle , the groove becomes deeper toward the tip of the paint nozzle, and the groove The air spray gun for painting is characterized in that the notch does not reach the paint path at the tip of the paint nozzle .

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