JPS635141B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a spray nozzle which is suitable for atomizing and painting paint using compressed air.

Generally speaking, the two methods of spraying to obtain the necessary atomized particles and spray pattern are the air spray method, in which compressed air collides with and mixes the paint stream, and the other is the air spray method, in which the paint is applied using a high hydrostatic pressure using a small oval orifice. It is broadly divided into airless spray methods.

Here, a high-pressure paint pump is required,
In addition, compared to the airless spray method, which requires changing the orifice depending on the coating conditions, the air spray method is cheaper and simpler, allows you to obtain patterns that match any object to be coated, and can obtain fine particles. Despite the disadvantage that it uses a large amount of compressed air and therefore causes a large amount of spray particles to scatter, it is widely used as a general-purpose painting device.

In view of the above circumstances, the present invention provides an atomizing nozzle for a spray gun that can achieve efficient atomization with a smaller amount of compressed air or lower compressed air pressure, in other words, with less energy in the air spray method. be.

Hereinafter, the present invention will be explained with reference to drawings of embodiments.

In FIG. 1, reference numeral 1 denotes a cap that is integrated with a screw 3 at the tip of the spray gun body 2, and the cap 1 is formed from two pieces, a front part 1a and a rear part 1b. An internal mixing chamber 4 is provided inside the chamber, and a spray nozzle 5 having a smaller diameter due to a step is arranged at the front end of the chamber. Reference numeral 6 denotes an inner nozzle installed in the center of the internal mixing chamber 4 with a compressed air passage 7 maintained between it and the inner wall. A valve seat 10 is provided, and the tip of a needle valve 11 disposed at the center is seated on the valve seat 10, and spraying and stopping of paint is controlled by moving the needle valve 11 back and forth. On the other hand, the paint passage 8 is connected to a paint container (not shown) via a joint and a paint supply hose. Further, the internal mixing chamber 4 communicates with the air passage 12 of the spray gun body 2 via the passage 7, and the step forming the small diameter portion of the internal mixing chamber 4, together with the outer periphery of the tip of the internal nozzle 6, It forms a narrow part, which improves the mixing of paint and air beyond that part (in front). Furthermore, the cap 1 has square air holes 13 which are bored opposite each other so as to cross and collide with each other in front of the central spray nozzle 5, and the square air holes 13 are connected to the air passage 12 of the spray gun body 2. It is constructed so that the amount of air is controlled by a square air control valve 14 arranged therein.

Next, this action will be explained. First, the spray gun main body 2 side has a known configuration, so the details will be omitted.

Here, when the needle valve 11 is moved back, the valve seat 10 of the inner nozzle 6 is opened, and the paint is sprayed from the paint passage 8 side through the spout 9 into the internal mixing chamber 4, and the paint is sprayed from the outside of the inner nozzle 6. The mixture is atomized by the high-speed airflow flowing through the passage 7 and is sprayed from the spray port 5.

In this case, the passage 7 outside the inner nozzle 6 is narrower than in the inner mixing chamber 4 downstream thereof, so that the compressed air is mixed with the paint as it expands and is efficiently atomized due to the confined chamber. It turns out.

Next, this atomized paint is atomized from the spray nozzle 5, and is further atomized by compressed air ejected from the corner air holes 13 located opposite to each other with respect to the spray stream, and is shaped into a desired pattern shape. Become.

FIG. 2 shows another embodiment. This changes the configuration of cap 1 to rear 1, which is the internal cap.
It has a double structure in which the tip part of b fits into the front part 1a which becomes an external cap, and an internal mixing chamber 4 is formed inside the central tip of the rear part 1b, and the rear part of the internal mixing chamber 4 is An inner nozzle 6 with a needle valve 11 similar to that described above arranged in the center is installed in the inner nozzle 6. In this case, the air passage 12 to the square air hole 13 and the passage 7 to the 4 internal mixing chambers are configured separately, thereby achieving more efficient atomization and pattern shape depending on the object to be coated and the type of paint. .

That is, according to the embodiment of the present invention, 1 the inner nozzle 6 has an enlarged portion 15 at the tip of the ejection port 9; For this reason, the paint discharged from the spout 9 is diffused in the enlarged portion, and the high-speed airflow flowing outside the enlarged portion improves the efficiency of atomization performed at the merging point at the tip. Depending on the properties of the paint, it is possible to increase the atomization efficiency by inserting an inclusion (not shown) into this enlarged portion.

2. A narrow part is formed by the tip of the inner nozzle 6 and the stepped part 16 in the cap 1, and the ventilation area of the narrow part is made smaller than the cross-sectional area of the internal mixing chamber 4. Therefore, the compressed air ejected from the narrow portion collides with the paint in the internal mixing chamber 4 and expands at the same time, increasing the atomization efficiency.

3. The flow rates of the compressed air jetting out into the internal mixing chamber 4 through the passage 7 and the compressed air flowing into the square air holes 13 are controlled separately (see FIG. 2). This makes it possible to form a pattern depending on the object to be coated.
Normally, a method is adopted in which the air to the internal mixing chamber 4 is kept constant and the flow rate of the air to the square air holes 13 is varied to change the ratio between the two (see FIG. 1).

As described above, the present invention uses a combination of an inner nozzle, a narrow air passage, an inner mixing chamber, and a corner air hole, so that the atomization of the paint is mixed and atomized in the mixing chamber by a small amount of air. Therefore, the paint particles after spraying have a much slower ejection speed and a wider range of paint (particle groups) than when they are ejected as a liquid, and they come into contact with the air ejected from the corner air hole. They collide and are effectively atomized. Furthermore, since the atomization is generally averaged while the forward speed is limited, the spray becomes stable with less scattering, resulting in good results for the finish of the coating.

[Brief explanation of the drawing]

The drawings show an embodiment of the present invention, and FIG. 1 is a longitudinal sectional side view of a main part, and FIG. 2 is a longitudinal sectional side view of another embodiment. 1... Cap, 4... Internal mixing chamber, 5... Spray port,
6... Inner nozzle, 7... Compressed air passage, 8... Paint passage, 9... Spout nozzle, 10... Valve seat, 11... Needle valve, 13
...Square air hole.

Claims (1)

[Claims] 1 In a spray nozzle equipped with a square air hole at the tip that cross-collides in front of the spray nozzle to form a spray pattern, the inner nozzle with a paint control needle valve placed in the center is seated on the nozzle at the end. The nozzle is disposed in a cap having an internal mixing chamber with a spray opening, and a stepped portion is provided on the inner wall of the cap located outside the tip of the inner nozzle to form a narrow portion between the tip and the tip of the inner nozzle. At the same time, the tip of the inner nozzle forms an enlarged part on the outlet side of the spout, which has a much larger diameter than the spout, and compresses the passage formed between the inner nozzle and the inner wall of the cap. A spray nozzle characterized by being connected to an air source.