JP3401293B2 - Spray gun for electrostatic coating - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fine particle paint sprayed from a spray gun by the action of an electrostatic field by applying a high voltage between the tip of a spray gun and an object to be coated. With respect to the spray gun for electrostatic coating which was made to suck the object to be coated, in particular,
The present invention relates to a spray gun for electrostatic coating which prevents electricity from leaking from the tip of a gun body through the gun body. 2. Description of the Related Art In a spray gun for electrostatic coating, a valve rod for opening and closing a valve port formed in a paint passage is connected to a piston of an air cylinder by a rod inserted into a sliding hole formed in a gun body. Because the valve port is opened and closed, the moisture in the compressed air carried into the air cylinder reaches the tip of the gun body through the gap between the sliding hole and the rod, The applied high-potential electricity is transmitted to the rear of the gun body by moisture, and leaks to the ground to lower the potential, so that normal electrostatic coating may not be performed. [0003] The problem to be solved by the present invention is to prevent the leakage of high voltage due to the transmission of moisture in the air cylinder to the tip of the gun body. According to the present invention, as a means for solving the above-mentioned problems, a valve port is provided in a paint passage formed in a gun body, and a valve rod which opens and closes in contact with and separates from the valve port is provided. While connecting to the piston of the air cylinder through the rod,
In a spray gun for electrostatic coating in which air is blown toward paint sprayed from a nozzle, air branched from an air supply passage flows through the sliding hole of the rod to the air cylinder side in the gun body. After that, an air passage to be discharged to the outside of the gun body was formed. According to the present invention, the air flows through the gap between the sliding hole of the gun body and the rod to the air cylinder side and is then discharged out of the gun body. Moisture that travels and enters the nozzle side is blocked by this air flow, and is discharged out of the gun body. For this reason, there is an effect that high voltage at the tip of the gun body is prevented from leaking, and normal electrostatic coating can be performed. An embodiment of the present invention will be described below with reference to the accompanying drawings. In the figure, reference numeral 1 denotes a synthetic resin gun body, which has an air cylinder 2 in which a piston 3 is slidably fitted in a cylinder 6 at the center of the rear end. Is provided with a coil spring 5, a pressurized air supply hole 7 is formed at a front end of a cylinder 6, and a rear end of the cylinder 6 communicates with the atmosphere through an opening 4. The piston 3 is connected to a first rod 8, and the first rod is connected to a collar 9 fitted on the gun body 1.
Of the gun body 1 is slidably inserted through a sliding hole 21 of the gun body 1 via an O-ring 18, and a second rod 10 is connected to the first rod. A paint reservoir 11 communicating with a paint passage (not shown) is formed at the distal end of the gun body 1 and communicates with a nozzle 14 through a valve port 13 of a valve seat 12. A bellows 15 for sealing the second rod 10 is fitted to the paint reservoir 11, and a valve rod 16 for opening and closing the valve port 13 is fixed to the bellows 15, and a coil mounted between the bellows 15 and the valve seat 12. It is urged in the valve opening direction by the elastic force of the spring 17. Pressurized air supply passages 19 and 20 are formed in the upper and lower parts of the gun body 1, and the upper pressurized air supply passage 19 blows a pressurized air to the paint flow ejected from the nozzle 14 to form an ejection pattern. The pressurized air supply passage 20 on the lower side blows pressurized air to the side edge of the jetting paint stream to promote atomization. A high-voltage cable (not shown) is embedded in the gun body 1 so that a high voltage is applied to the nozzle 14. The above is a known spray gun for electrostatic coating. When pressurized air is supplied from the pressurized air supply hole 7 into the cylinder 6, the piston 3 retreats against the elasticity of the coil spring 5, The first rod 8 and the second rod 10 connected thereto are retracted, and the valve rod 16 is moved by the elastic force of the coil spring 17.
Is retracted, the valve port 13 is opened, and the paint in the paint pool 11 is ejected from the nozzle 14. Then, the pressurized air is blown toward the jetting paint flow to flatten the pattern,
And atomization is promoted. In such a known spray gun for electrostatic coating, since the pressurized air supplied into the cylinder 6 contains moisture, the collar 9 slides with the reciprocating movement of the first rod 8. Hole 21 and sliding hole 22 of gun body 1
The moisture in the cylinder 6 passes through the gap between the first rod 8 and the second rod 10 and reaches the tip of the gun body 1 to which the high voltage is applied, and the high voltage is transmitted to the rear part of the gun body 1 by the moisture. The potential of the tip of the gun body may be reduced by leaking to the ground, and normal coating may not be performed.However, in the present embodiment, this is prevented by adopting the following configuration. I have. That is, a first air passage 23 is formed from the upper pressurized air supply passage 19 to the sliding hole 22 of the gun body 1 and opened through the sliding hole 21 of the collar 9 through the inside of the gun body 1. 4, a second air passage 24 is formed. Therefore, a small amount of pressurized air is discharged from the upper pressurized air supply passage 19 to the atmosphere through the gap between the sliding holes 22 and 21 and the first rod 8. Therefore, the water that travels forward along the first rod is pushed back by this air flow and is released to the atmosphere, so that the high voltage is prevented from reaching the front of the gun body and leaking. A simple electrostatic coating can be performed. The air flow may branch off from the lower pressurized air supply passage 20.

[Brief description of the drawings] FIG. 1 is a sectional view of one embodiment of the present invention. [Explanation of symbols] 1: Gun body 2: Air cylinder 3: Piston 4: Opening 6: Cylinder 8: 1st rod 10: 2nd rod 13: Valve mouth 14: Nozzle 16: Valve rod 19, 20: Pressurized air supply path 21, 22: sliding hole 23, 24: Air passage

Claims (1)

(57) [Claims 1] A valve port is provided in a paint passage formed in a gun body, and a valve rod which opens and closes in contact with and separates from the valve port is connected to a piston of an air cylinder via a rod. In addition, in the spray gun for electrostatic coating in which air is blown toward the paint ejected from the nozzle, the air branched from the air supply path is inserted into the gun body through the sliding hole of the rod through the air cylinder. A spray passage for electrostatic coating, wherein an air passage which is discharged to the outside of the gun body after flowing to the spray gun is formed.