JPH0361504B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a spray nozzle that applies high pressure to paint and sprays it from the nozzle to atomize it. In particular, in order to achieve a good and efficient atomization state, the paint is sprayed using high-pressure, high-density compressed air. This relates to an internal mixing type spray nozzle that ejects into the air and atomizes the air together with the compressed air.

Many methods have been proposed to atomize liquids, particularly in painting. Two methods are used: the air spray method, in which compressed air collides with the paint, and the other is the air spray method, in which high pressure is applied to the paint and the paint is sprayed out forcefully from a small atomizing nozzle orifice. The most commonly used method is the airless spray method, which atomizes by colliding with the atmosphere.

Generally, the air spray method, in which paint is atomized using compressed air, has the advantage that various spray conditions and spray patterns can be obtained by varying the pressure, amount, direction, etc. of the compressed air that collides with the flow of paint. There is. However, this air spray method has serious problems such as the use of a large amount of compressed air, which increases the scattering of the sprayed particles, resulting in deterioration of the coating environment and reduction in coating efficiency. On the other hand, the airless spray method, which uses liquid pressure to atomize without using compressed air, has the advantage of less scattering of paint particles and high coating efficiency, and it also sprays at high pressure. This also has the advantage of being able to spray a large amount of highly viscous paint.

Based on the above, the airless spray method is generally used as an excellent painting method in terms of environmental protection and workability in painting work, but depending on the type of paint, the pressurizing pressure of the paint may be low. If the spray nozzle is used too much, uniform atomization is not carried out, and a pattern with striped non-uniform distribution is formed at both ends. In addition, the airless spray method still has many difficulties in achieving proper painting, as it is not possible to adjust the amount of paint sprayed or the pattern width without replacing the spray nozzle.

Therefore, in order to solve this problem, the pressurization of the paint is lowered and the spray pattern is modified by using compressed air flow for the sprayed paint particles to form an appropriate pattern and spray with less scattering. A possible direction was proposed. This method applies high pressure through a lip-shaped opening to form a flat paint spray stream, and then jets a compressed air stream toward this flat spray stream, which is different from the conventional air spray method. In comparison, since spraying can be performed at a sufficiently low pressure, it is possible to eliminate the risk of high pressure, and it is also possible to improve durability by lowering the pressure of the pump. In addition, the spray nozzle can have a larger opening cross-sectional area than if the same amount of paint is ejected, which can prevent early paint clogging and significantly reduce wear on the nozzle opening. This makes it an excellent spray nozzle.

However, in this method, compressed air is caused to collide with a flat fan-shaped paint jet flow, and atomization itself at the colliding portion is performed by the action of the compressed air. Therefore, the problem of paint scattering due to compressed air injected for atomization still remains.

The present invention has been made in view of the above-mentioned circumstances, and provides a spray nozzle that increases the atomization efficiency in hydraulic atomization and creates a suitable atomization state. That is, the present invention is a spray nozzle that ejects pressurized paint as a flat paint stream from a paint nozzle having an approximately lip-shaped opening, and atomizes the paint by collision with air. An air nozzle with the center opening of the opening portion located in front of the injection port is detachably attached, and the air nozzle faces the center port of the air nozzle and is perpendicular to the paint flow ejected from the injection port of the paint nozzle, or perpendicular to the paint flow. forming an internal passage in the air nozzle for compressed air to converge and collide;
Compressed air is introduced and injected into the internal passage to form a high-pressure area at the center opening of the air nozzle, which enables efficient atomization and prevents paint particles from scattering. It is something.

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

Fig. 1 is a cross-sectional view of the spray nozzle of the present invention, in which the paint nozzle 1 has an internal hole that is open at the rear and has a recess at the tip formed in a substantially hemispherical shape, and a substantially V-shaped groove is formed from the outside so as to reach the recess at the tip. and has a known structure having an injection port 1' having a substantially lip-shaped opening,
The paint nozzle 1 is inserted and fixed into a tip holder 2 and attached to a nozzle base 4 at the tip of a spray gun body 3. A paint passage 5 passes through the center of the nozzle base 4, and a needle valve 6 is inserted into the paint passage 5 so as to be able to move forward and backward, and a spray gun body 3 is provided on the outside.
An air passage 8 communicating with the air passage 7 is provided at the tip of the nozzle base 4, and an air nozzle 9 is connected to the paint nozzle 1.
An air cap 11 is attached to the outside of the air nozzle 9.
is screwed on.

The air nozzle 9 is provided with an opening 12 at the center, forming a central opening for the spray stream. Further, the paint stream injected from the injection port 1' of the paint nozzle 1 is atomized and atomized from the center opening of the opening 12 of the air nozzle 9. Further, an internal passage 13 is formed inside the air nozzle 9 and is formed to converge and collide perpendicularly to the paint flow or against the paint flow, and the air flow from the air passage 8 is introduced into the paint nozzle 1. Compressed air is injected toward the injection port 1'.
Thereafter, the compressed air is ejected forward from the central opening 12 of the air nozzle 9. Note that the opening 12
is formed so as to taper toward the front so as not to restrict the spread of the spray flow.
What is important in this case is that the outlet portion of the injection port 1' has a high air density, and the paint is formed so that it is sprayed into the high density air and atomized. The structure shown in the drawing is one example, and the opening 12 is located in front of the injection port 1', and the cross-sectional area of the opening is smaller than the cross-sectional area of the passage at the injection port. That is, the ventilation cross-sectional area of the injection port 1' is equal to the opening 1 of the air nozzle 9.
2, the air flow rate is slow and the pressure is maintained high. Therefore, if the paint sent into the paint nozzle 1 is not pressurized, the compressed air will flow back into the paint passage 5.

Reference numeral 14 denotes a side air port provided in the air cap 11 for adjusting the pattern shape.

Next, to explain the operation of the present invention, first, by pulling the trigger (not shown) of the spray gun body 3, the needle valve 6 is moved back, and the paint is introduced into the paint passage 5 of the spray gun body 3 under pressure. The paint is injected from the injection port 1' of the paint nozzle 1, and compressed air passes from the air passage 7 of the spray gun body 3 through the air passage 8 in the nozzle base 4 earlier than the injection of the paint.
The paint is injected from the central opening 12 through the internal passage 13 of the air nozzle 9, and the paint passes through the compressed air layer toward the opening 12 of the air nozzle 9 and is atomized to the outside. In this case, the paint is sprayed at a pressure of 30 to 100 Kg/cm ² , usually 50 to 70 Kg/cm ^2, and
The compressed air is injected from 0.5 to 3.0 kg/
It has a pressure of cm ² and sprays paint faster than a normal air spray gun. Therefore, when paint is atomized through this compressed air layer, atomization is more efficient because the compressed air layer creates a denser wall of air than under normal atmospheric conditions.

It is preferable that the internal passage 13 of the air nozzle 9 be formed so that it converges and collides with the paint flow from the paint injection port 1' perpendicularly or converges and collides against the paint flow. This means that air pressure is applied in a direction that prevents the injection of paint, and the injection port 1' is placed under pressure higher than atmospheric pressure.

As described above, the present invention injects pressurized paint as a flat paint stream from a paint nozzle having an approximately lip-shaped opening, and also positions the tip of the paint nozzle within an air nozzle, so that the paint is sprayed inside the air nozzle. forming an internal passage so that the compressed air converges and collides with the paint injection port perpendicularly or against the paint flow;
Since compressed air is injected from the opening through the internal passage, the paint is sprayed to the outside through the compressed air layer toward the opening of the air nozzle. At this time, the compressed air layer creates a wall of air that is denser than in normal atmospheric conditions, so paint atomization is performed efficiently, and the resistance during atomization reduces the momentum of paint particles, eliminating unnecessary Splashing of paint particles can be reduced.

Further, since the atomized paint particles are sprayed onto the object to be coated while being surrounded by the airflow ejected from the opening of the air nozzle, scattering to the surroundings and scattering of rebound particles are prevented. In addition, by configuring the opening to taper forward, the ejected airflow forms an air curtain that wraps around the spray pattern in a tapered manner.
It is possible to more effectively prevent paint particles from scattering.

[Brief explanation of drawings]

The drawings show an embodiment of the present invention; FIG. 1 is a sectional view, FIG. 2 is a front view, and FIG. 3 is an enlarged sectional view of main parts. 1... Paint nozzle, 1'... Injection port, 9... Air nozzle, 12... Opening, 13... Internal passage.

Claims (1)

[Scope of Claims] 1. A spray nozzle that ejects pressurized paint as a flat paint stream from a paint nozzle having an approximately lip-shaped opening and atomizes it by collision with air, An air nozzle with the center opening of the opening portion located in front of the injection port at the tip is removably attached, and the air nozzle is directed toward the center port of the air nozzle perpendicularly to the paint flow jetted from the injection port of the paint nozzle, or the paint is An internal passageway for compressed air that converges and collides against the flow is formed in the air nozzle, and the compressed air is introduced into the internal passageway and injected to form a high-pressure area at the center opening of the air nozzle. Mixing spray nozzle. 2. The internal mixing spray according to claim 1, in which a paint having a pressure of 30 to 100 kg/cm ² is injected from a paint nozzle and compressed air having a pressure of 0.5 to 3 kg/cm ² is injected from an air nozzle. nozzle. 3. The internal mixing spray nozzle according to claim 1, wherein the opening in which the center opening of the air nozzle is located has a shape that tapers outward.