JPH0360753A - Low-pressure pulverizing spray gun - Google Patents

Abstract

PURPOSE:To form the pulverized spray pattern suitable for coating with the low air pressure by executing mixing atomization by a coating material and compressed air in a spraying port and bringing the compressed air flow to make reatomization and the formation and adjustment of the patterns into collision against this spray flow. CONSTITUTION:This gun has a single circular hole nozzle 21 opened into an air cap 30 having a lip-shaped spray aperture 31 and the secondary air flow is brought into collision against the flat spray flow in which the ejected coating material is mixed and sprayed by the primary air flowing on the outer periphery of the nozzle 21, thereby executing pattern adjustment of the spray flow. A secondary air path 27 distributed by an air passage 26 for the above-mentioned primary air is provided in this spray gun and a means 19 for regulating the flow rate is provided in this secondary air passage 27. As a result, the pulverized spray pattern suitable for coating is obtd. by the air pressure as low as about 1/5 the pressure of the conventional air spray.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a spray gun that uses compressed air to atomize a spray material such as paint and spray the atomized material. especially,
The present invention relates to a spray gun that can perform sufficient atomization when the pressure of compressed air is as low as 1 kg f /ctl or less.

[Prior Art] So-called air spray guns, which atomize and spray using compressed air, are broadly classified into external mixing methods and internal mixing methods, depending on the atomization method. With the external mixing method, the paint sprayed from the paint nozzle is mixed at a rate of 3 to 5 kg f/a&
It is mixed outside the spray gun by compressed air ejected under the pressure of By colliding with forming air, the shape of the spray can be changed, making it possible to spray in a pattern of a size suitable for the object to be coated.

In addition, an internal mixing spray gun is a spray gun that sprays paint from a nozzle that opens inside an air cap with a spray port, mixes the paint in the air cap, atomizes it, and then sprays the mixture in a gas-liquid state from the air cap. . Therefore, the shape of the spray is almost determined by the shape of the spray port, and the diameter of the spray particles cannot be made too fine by external mixing.

Spray guns using these atomization methods have been in practical use for a long time, and their contents are widely known to those skilled in the art.

One of the biggest problems with these atomization systems is that the atomized particles often scatter. One possible means to improve this is atomization using low-pressure air, and airless atomization in which air for controlling the spray is used in combination with atomization by liquid injection has been considered, and its practical use is progressing.

Atomization using low-pressure air uses a large volume of low-pressure air to prevent paint from bouncing back and scattering to the surrounding area, but there is a limit to the amount of paint that can be ejected.

It is as low as about 200 cc/rtm, and its practical application range is narrow. Since this type of device also has a problem with the coarseness of the particle size, many devices that attempt to improve this by using hot air are often used in practice.

In the case of airless atomization, so-called high-pressure paint is injected and atomized from a nozzle with a lip-shaped opening, and compressed air is used to further control the spray flow.

In this type of system, there is an internal system in which a hydraulic atomizing nozzle with a lip-shaped opening is placed inside a spray nozzle that has a lip-shaped opening similar to that of air spray, and a hydraulic atomizing nozzle is installed externally. There is an external method in which air collides with the spray stream, and the external method is practically adopted in most cases.

[Problems to be solved by the invention] In any case, conventional atomization methods have their own problems, and a sprayer that uses low-pressure air and whose pattern shape is fine in particle size and can be adjusted to a range suitable for painting. Couldn't get the gun.

That is, in the case of an internal mixing type spray gun, which can easily be set to a relatively low pressure, the pattern cannot be adjusted as described above, and the problem arises that the air cap must be replaced. Furthermore, when spraying low-viscosity paint, the center of the oval pattern tends to become thinner, which has a negative effect on the finish of the sprayed surface.

In addition, in external mixing type low-pressure spray guns, when the spray volume is increased, the particle size becomes extremely coarse.
It is limited to about 150cc/min or less. Furthermore, even with the airless method, since the nature of the mist is based on hydraulic atomization, it cannot be made fine enough to be used in finishing painting, and low-pressure air is also added to this. However, this method only improves the non-uniformity of the spray, but cannot achieve the level of atomization of the mist, and ultimately requires high-pressure air, resulting in increased dispersion.

In the case of the present invention, the purpose of the present invention is to achieve atomization of paint to the extent that it can be used for finishing coating using compressed air of 1 kgf/d or less, preferably 0.7 kgf/d or less, and to obtain a spray gun with less scattering. It is said that

[Means for Solving the Problems] In order to solve the above-mentioned problems, the present invention provides a single circular hole nozzle that opens in an air cap having a lip-shaped spray opening, and the outer circumference of the nozzle is By the flowing primary air,
A spray gun that forms a flat spray stream in which sprayed paint is mixed and sprayed, and adjusts the spray stream by colliding with the flat spray stream, and further includes a secondary air passage distributed from the air passage for the primary air. The secondary air passage is provided with a flow rate adjusting means. In addition, for the flat spray stream, a secondary air stream that collides in front of the flat spray stream is injected from a pair of square nozzles that open diagonally forward from the rear on both sides of the flat plane, so that the secondary air stream collides with the flat spray stream in the same direction as the flat spray stream. It is a flat airflow that expands. Further, another secondary air is injected and collided with an injection port provided on the long axis side of the flat spray stream and diagonally rearward of the spray opening.

Furthermore, a first secondary air stream that sprays and collides with the flat spray stream that is atomized by the primary air stream from the lip-shaped spray opening while expanding in the same direction as the flat spray stream, and a first secondary air stream that sprays and collides with the flat spray stream while expanding in the same direction as the flat spray stream; An air hole is provided for injecting a second secondary air flow which is injected and collides from the long axis direction of the flat spray stream, and an independent secondary air passage communicating with each air hole is provided, and the compressed air is passed through these air holes. A distribution means is provided to supply either one of the secondary air passages.

[Operation] According to the above-mentioned configuration means, an air flow is formed around the outer periphery of the nozzle tip that flows toward the spray opening in front, and then the paint ejected from the nozzle is sucked by the air flow and flows toward the tip. By ejecting and increasing the contact area with the air flow, the particles are efficiently atomized and sprayed from the spray opening. The spray shape at this time is an oval flat pattern depending on the lip-shaped opening. Furthermore, the flat pattern is further crushed by secondary air jetted onto the plane of the pattern from a pair of square nozzles that are jetted diagonally forward from the rear, resulting in a more spread out pattern that is delivered to the surface to be coated. . The secondary air jet at this time is injected from both sides as a parallel flat spray stream that expands in the same direction as the spray pattern.
Crush the pattern to form a uniform spray pattern.

Moreover, since the flow rate adjusting means for primary air and secondary air is provided, the rua of the pattern and the atomization state can be adjusted, and the atomization state suitable for the paint and the surface to be coated can be obtained.

By making the square nozzle separable, it is possible to manufacture individual nozzles with high dimensional accuracy, and by replacing them,
It also becomes possible to obtain variations in pattern formation.

In addition, if the secondary air is injected in a direction perpendicular to the above direction, that is, from the injection holes arranged in the longitudinal direction of the shoulder car spray pattern, it will work in the direction of making the pattern smaller and the spread will be smaller. A circular pattern can be formed.

In the spray gun of the present invention, primary air mainly used for atomization and secondary air for the putter 718m are arranged in a flat pattern with air holes arranged in the longitudinal direction and in the direction perpendicular to the longitudinal direction, and the air holes are adjusted in either direction. In order to send in and spray air, the range of pattern adjustment expands in the expanding and contracting directions for patterns that depend on the shape of the spray nozzle, and from an oval primary spray pattern to a larger pattern to circular. A wide range of adjustment is possible up to the pattern.

[Example] FIG. 1 is a sectional view showing the overall configuration of a spray gun embodying the present invention.

The main body 1 has a gun barrel 2 and a grip 3, and has an air nipple 4 attached to the lower part of the grip 3, and is configured to send compressed air through a through hole 5 to an air valve provided at the upper part.

The air valve section includes an air valve 8 provided inside an air conditioning pipe 7 that is inserted into an air conditioning hole 6 formed from the rear of the gun barrel 2. The air conditioning pipe 7 has a hole 9 that communicates from the outside to the inside, and the hole 9 is opened by rotating the air conditioning pipe 7.
The air flow rate changes depending on how well the through hole 5 and the through hole 5 match. A knob 10 is provided to rotate the air conditioning pipe 7. The air valve 8 is pressed against the seat 12 of the main body by a spring 11 to stop the supply of compressed air. A needle valve 13 extending to the tip of the gun barrel 2 passes through the center of the air JF-8, and a spring I4 is attached to the rear of the needle valve 13, and an opening adjustment knob that holds the spring I4 under pressure and regulates the amount of retraction of the needle valve 13 is inserted. 15 are provided.

In front of the air valve 8, an air valve rod 17 is provided on the outside of the second lift 13 by operating the trigger 16.

By operating the trigger 16, the air valve 8 is retracted to send compressed air into the forward air distribution chamber I8. When the trigger 16 is further pulled, the needle valve 13 is moved back by the rear end of the air valve 8.

A distribution valve 9 is rotatably fitted into the air distribution chamber 18 and is rotated by an external knob 29.

There are three air passages from this air distribution chamber 18 toward the front of the barrel 2, one of which is always connected to the distribution chamber 18, and the other two passages are connected to the distribution valve 19. The flow area varies depending on the rotational position of the provided recess 20, and the flow rate can be adjusted. Therefore, if the change in the flow area in the rotating contact portion is determined by the recess 2o of the distribution valve 19, it is possible to limit the distribution amount arbitrarily.

An atomizer is provided at the tip of the gun barrel 2.

A paint nozzle 21 that sprays paint is screwed into the tip of the main body, and the tip of the needle valve 13 is connected to the paint nozzle 2.
It hits the inside of nozzle port 22 of No. 1 and stops the paint. The outside of this paint nozzle 21 engages with the main body 1 and has two passages 2.
A primary air passage 26 and a passage 23 are formed so that one of the secondary air passages, an air passage 27, and a passage 24 communicate with each other.

-9 The paint nozzle 21 is covered by a tip cap 30, and the nozzle port 22 is arranged inside a spray port 31 that opens at the center of the tip of the tip cap 30.

The spray nozzle 31 has a cylindrical inlet 32, a conical or approximately spherical end, and a V-shaped groove 3 in the center from the outside.
3 and has a lip-shaped opening. A primary air chamber 40 is formed as a tapered surface 35 in front of the inlet portion 32, and the tapered surface 35 and the paint nozzle 21
The compressed air from the passage 23 flows between the outer diameter 36 of the tip and the outer diameter 36 of the tip.

It has been shown that the larger the flow area, the smaller the atomized particles, and therefore it is preferable to set it at least equal to or larger than the opening.

Further, the outside of the spray nozzle 31 forms a conical outer surface 34 like the inside, and the thickness of the opening is set to F='l<< as much as possible. Furthermore, a square cap 37 is provided which engages with the outer surface 34 and has a corner facing symmetrically with respect to the spray axis, is integrated with the tip cap 30, and is removably fixed to the tip of the main body 1 by a cover 38. ing.

A corner nozzle 43 is provided at a corner 42 of the corner cap 37 to eject a flat air stream in an oblique direction.

In the embodiment, a square nozzle having an opening shape similar to that of the spray nozzle 31 is shown;
With respect to the flat spray flow from 1, the flat air flow is made to spread in the same direction from the plane side, so that the jet flow collides with almost the entire area of the flat spray flow. Since this square nozzle 43 injects a flat air stream, it is formed into a hole with a conical or spherical inner surface, and a lip-shaped opening is formed from the outer surface, similar to the spray nozzle described above. As another embodiment, FIG. 6 shows a method in which a square nozzle 43 is separately incorporated as a separate structure. Via the passage 44 of the corner cap 37, it communicates with the other air passage 25 of the secondary air passages surrounded by the outside of the paint nozzle 21 and the inside of the cover 38, and this air passage 25 is connected to the distribution valve 19. The other air passage 28 from
It communicates with

- On the side of the directional cap 37 orthogonal to the square nozzle 43, spray ports 45 are provided at positions facing each other with the spray port 31 as the central axis, and are also formed to spray diagonally in 1)9 directions. ing. That is, as shown in FIG. 2, the spray is sprayed toward the long diameter side ends of the spray stream, and the spray pattern is reduced. This injection port 45 is communicated with the air passage 24 of the paint nozzle 21 via a passage 46 provided in the tip cap 30.

Therefore, the two secondary passages 27° 28 from the distribution valve 19
One side is ejected from the injection port 45 and the other side is ejected from the square nozzle 43. The secondary air is communicated with either by the distribution valve 19, and when it is supplied to the square nozzle 43 side, it is sprayed in a large spray pattern, and when it is supplied to the injection port 45 side, it is sprayed in a small, almost circular spray pattern. Ru.

As in the present invention, it is difficult to determine the size of the pattern for spray particles that are air atomized depending on the shape of the spray nozzle in advance as a flat pattern, and it is not possible to have a large adjustment range. Now, since the adjustment is made by dividing the spray pattern so that it is large on one side and small on the other, the range is wide and the necessary spray pattern can be easily selected.

[Effects of the Invention] As described in detail above, the present invention uses paint and compressed air to mix and atomize in the spray nozzle as an atomization means in painting, and further atomizes this spray flow and forms a pattern. ,
By colliding compressed air streams that perform gu, an atomized spray pattern suitable for painting can be obtained with extremely low air pressure of about 115% compared to conventional air spray. Since no means are used, the paint can be force-fed using the low-pressure spray air mentioned above, and no special means for pressurizing the paint is required, so it can be easily used with a spray gun similar to conventional air spray, etc. You can get the following effect.

Of course, it goes without saying that conventional problems can be improved, such as prevention of scattering of paint particles and improvement of the working environment by lowering the blowing air pressure mentioned above.

[Brief explanation of drawings]

FIG. 1 is a sectional view of a spray gun showing an embodiment of the present invention. FIG. 2 is an enlarged view showing a cross section taken along the line ■-■ in FIG. 1, and FIG. 3 is an enlarged view showing a cross section taken along the line m-nr in FIG. Figure 4 is the first
Figure 5 is a left side view of the tip atomizer part in Figure 4.
It is an enlarged sectional view showing an OB cross section. FIG. 6 is a sectional view of the tip of a spray gun showing another embodiment of the present invention. 8...Air valve 13...Needle valve 19...Distribution valve 21...Paint nozzle 30...Tip cap 31...Spray port 33...V-shaped groove 37...Square cap 43... Square nozzle 45... Injection port

Claims (1)

[Scope of Claims] 1) A flat spray stream having a single circular hole nozzle opening in an air cap having a lip-shaped spray opening, in which the ejected paint is mixed and sprayed by primary air flowing around the outer circumference of the nozzle. On the other hand, in a spray gun that adjusts the pattern of the spray flow by colliding secondary air flows, a secondary air passage is provided which is distributed from the air passage of the primary air, and the secondary air passage is equipped with a flow rate adjusting means. A low-pressure atomization spray gun. 2) It has a single circular hole nozzle that opens in an air cap with a lip-shaped spray opening, and the primary air flowing around the outer circumference of the nozzle creates a flat spray stream in which the ejected paint is mixed and atomized, whereas the secondary air In a spray gun that adjusts the spray pattern by colliding streams, the secondary air stream that collides in front of the flat spray stream has a pair of corners that open diagonally forward from the rear of both sides of the flat plane. A low-pressure atomizing spray gun in which a flat air stream is ejected from a nozzle and expands in the same direction as the flat spray stream. 3) It has a single round hole nozzle that opens in an air cap with a lip-shaped spray opening, and the primary air flowing around the outer circumference of the nozzle is used to mix and spray the ejected paint into a flat spray stream, whereas the secondary air In a spray gun that adjusts the spray pattern by colliding streams, low-pressure fine particles are produced by spraying and colliding secondary air from an injection port located on the long axis side of the flat spray stream and diagonally rearward of the spray opening. chemical spray gun. 4) A first secondary air stream that sprays and collides with a flat spray stream that is sprayed by the primary air stream from a lip-shaped spray opening while expanding in the same direction as the flat spray stream, and a first secondary air stream that sprays and collides with the flat spray stream while expanding in the same direction as the flat spray stream; air holes are provided for injecting a second secondary air flow that is injected and collides with the flat spray stream from the long axis direction, and independent secondary air passages are provided that communicate with each of the air holes, and from the primary air passage , a spray gun provided with distribution means for supplying compressed air to either one of these secondary air passages.