JPH0724366A - Spray gun for static powder coating application - Google Patents

Abstract

PURPOSE:To sufficiently and electrostatically charge a static electricity by increasing the contact opportunity between the powder coating and the interior wall of the spray gun and favorably depositing the powder coating on an object to be coated by installing a screw like revolving blade in a passage of the powder coating in the spray gun and thus imparting a revolving flow to the powder coating. CONSTITUTION:In a spray gun 50, a powder coating 40 and atomized air 72 are introduced respectively from supply openings 18, 20 into a connector 2 to be mixed. The mixture, after being sent by pressure to a tube 10 having a conductive layer 8 to be coated which is engaged with a gun body 6 bonded with the connector 2 through a sealant 4, is hit to a screw like revolving blade 12 supported in the tube 10. The vortex of the powder coating is formed forcedly to increase the contact opportunity with the inner wall of the tube 10 so that the powder coating is charged sufficiently with static electricity generated by the friction. The powder coating 40 is ejected from a clearance between a nozzle 14 and a deflector 16 to be deposited favorably on the surface of an object to be coated.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improved spray gun used for electrostatic powder coating.

[0002]

2. Description of the Related Art For electrostatic powder coating, a corona pin is provided on a spray gun for spraying powder coating, and a high voltage is applied to the corona pin to charge the powder coating.
A triboelectric charging method in which powder coating material is triboelectrically charged inside a spray gun is well known. FIG. 2 shows a general apparatus configuration used for triboelectric electrostatic powder coating.

In FIG. 2, reference numeral 30 is a fluidized bed type hopper of the pressure gas blowing type, and the hopper 30 delivers the pressurized gas regulated by a controller 34 through a pipe 32 to the fluidized bed type hopper 30. Is introduced into the gas chamber 36 at the bottom of the porous plate 38 and blown into the hopper 30 through the porous plate 38.
The powder coating material 40 on the upper side of is stored in a fluidized state. Four
Reference numeral 2 denotes an ejector pump installed on the upper lid of the hopper 30. The ejector pump 42 receives the pressure gas adjusted by the control device 34 from the pipe line 44, and the venturi action in the ejector pump 42 causes the hopper 30 to move. The powder coating material 40 in a fluid state is sucked from a suction pipe 46 inserted therein, further transported to a spray gun 50 through a hose 48, and sprayed from the spray gun 50 toward an object to be coated. There is.

As a conventional ejection gun 50, one having a structure shown in FIG. 3 or Japanese Unexamined Patent Publication No. 56-10855.
A structure as known from No. 4 is generally used. Explaining the conventional spray gun shown in FIG. 3, the spray gun 50 is configured integrally with a connector 52 having a powder paint supply port 64 and an atomizing air 72 supply port 66. Shaft core 54 and connector 52
With the shaft 54 and a predetermined gap 56 on the downstream side of the shaft 5
4 is composed of a cylindrical Gumbody 58 and a deflector 62 attached to the shaft core 54 via a shaft 60. Hose joints 68 and 70 are provided at the supply port 64 and the supply port 66, respectively.

The spray gun 50 introduces the powder coating material 40, which is pressure-fed from the ejector pump, into the inside of the connector 52 through the supply port 64, and the atomizing air 72 introduced through the supply port 66.
Together with, the gap 5 between the shaft core 54 and the Gumbo body 58
It is triboelectrified at 6, is ejected from the tip of the Gumbo body 58, is atomized by the action of the deflector, and is applied toward the object to be coated.

[0006]

The conventional jet gun described above has the following problems. That is, in the ejection gun shown in FIG. 3, since the gun body 58 has a straight tubular shape, the powder coating material flows linearly, and there is little chance of contact between the powder coating material 40 and the inner wall of the gun body 58. The body paint was not sufficiently charged with static electricity due to friction. Therefore, the adhesion rate of the powder coating material ejected from the ejection gun 50 toward the object to be coated was also poor. In addition, in order to improve this, there is also one that uses a corona charge charging method together with a corona pin, but when using the corona charging method together, it is a drawback of the corona charging method, from the characteristics of the electric line of force called the Faraday cage effect. However, the powder coating material is less likely to get into the depressions of the article to be coated, and the powder coating material is likely to adhere to the convex portions of the article to be coated, resulting in a non-uniform coating film thickness and deterioration in quality.

In the jet gun having the structure known from Japanese Patent Laid-Open No. 56-108554, a large number of elongated charging tubes have spiral or irregular bent portions.
Since it is provided, the structure is complicated and expensive, there are problems that cleaning and maintenance at the time of color change are troublesome, and the elongated charging tube is clogged.

The present invention has been made in view of the above-mentioned problems, and it is an object of the present invention to provide a spray gun for electrostatic powder coating which has a simple structure, high electrostatic tribocharging efficiency, and easy maintenance. It is intended.

[0009]

In order to solve the above-mentioned problems, the present invention has the following structure. In other words, it is a spray gun used for electrostatic powder coating, characterized in that a screw-shaped swirl blade is provided in the powder paint passage of the spray gun to impart a spiral swirl flow force to the powder paint flow. The composition of the spray gun for electrostatic powder coating is as follows.

[0010]

According to the jet gun of the present invention, the powder paint supplied from the ejector pump to the jet gun is forcibly turned into a vortex by the action of the screw-shaped swirl vanes together with the atomized air, and the inner wall surface of the jet gun is forced to flow. The chances of contact with the powder coating are increased, and the electrostatic charging efficiency due to friction of the powder coating is improved. Therefore, it is possible to obtain a uniform coating rate and film thickness on the object to be coated, and to obtain a high quality coating film. Moreover, the structure is simple and maintenance is easy.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the spray gun for electrostatic powder coating of the present invention will be described below with reference to the drawings. FIG. 1 is a sectional view of an essential part of an electrostatic powder coating spray gun according to the present invention. In the figure, the ejection gun 50 is composed of a connector 2, a gun body 6, a tube 10, a swirl vane 12, a nozzle 14, a deflector 16, and the like. The connector 2 has a supply port 18 for powder coating material 40
And a supply port 20 for atomizing air 72, and the supply port 18 and the supply port 20 are provided with a hose joint 22 and a hose joint 24, respectively. A tubular gum body 6 is connected to the connector 2 via a sealing material 4 such as an O-ring. A tube 10 made of a fluororesin having a coating layer 8 whose outer periphery is coated with a conductive material on the gum body 6.
Further, a swirl vane 12 having a helix angle like a screw is supported and fixed in the tube 10. The swirl vane 12 is provided with a deflector 16 at the tip of the lot 26 via a rod 26 extending to the tip. A nozzle 14 is provided at the tip of the gun body 6 with a sealing material 4 such as an O-ring interposed. The jet gun of this embodiment has the structure described above, and when used, the coating layer 8 of the tube 10 is grounded by a conductive cable (not shown).

Next, the operation of this embodiment will be described. This spray gun 50 is a powder coating 4 which is pressure-fed from an ejector pump.
0 is introduced into the inside of the connector 52 from the supply port 18, and together with the atomized air 72 introduced from the supply port 20, it is pressure-fed toward the tube 10 fitted in the gun body 6 and hits the swirl vane 12. Here, the flow of the powder coating material is forcibly turned into a spiral vortex flow by the action of the swirl vane 12. Due to this eddy flow, the powder coating material 40 increases the chance of contact with the inner wall of the tube 10, and the static electricity generated by friction is sufficiently charged. Then, the powder coating material 40 sufficiently charged by the eddy current is atomized from between the nozzle 14 and the deflector 16 provided at the tip of the ejection gun 50 toward the object to be coated, and is sprayed on the surface of the object to be coated. Adhere to.

In this embodiment, one swirl vane 12 is provided, but it may be provided in multiple stages at a predetermined interval in the axial direction. The charging efficiency is further improved by providing in multiple stages. The original purpose of the jet gun of the present invention is to use it as a triboelectrification system, but it can also be applied to a combination of a corona pin and a corona charge charging system.

[0014]

As described above, according to the present invention, electrostatic powder provided with screw-shaped swirl vanes for imparting a spiral swirl flow force to the powder paint flow in the powder paint passage of the jet gun. Since the spray gun is used for body painting, the powder paint flows as a spiral vortex inside the spray gun, increasing the chances of contact with the inner wall of the spray gun and improving electrostatic charging efficiency. It Moreover, the structure is simple and maintenance is easy.

[Brief description of drawings]

FIG. 1 is a sectional view of a main part of an ejection gun for electrostatic powder coating according to the present invention.

FIG. 2 is a diagram showing a general device configuration of a triboelectric electrostatic powder coating device.

FIG. 3 shows a conventional ejection gun.

[Explanation of symbols]

2 Connector 6 Gumbo day 6 Tube 12 Swirl blade 14 Nozzle 16 Deflector

Claims (1)

[Claims] 1. A spray gun used for electrostatic powder coating, comprising screw-shaped swirl vanes for giving a spiral swirl flow to the powder paint in the powder paint passage of the spray gun. A spray gun for electrostatic powder coating.