JPH02102758A - Spraying method for preventing sticking of coating and spray gun - Google Patents

Abstract

PURPOSE:To prevent the levitating coating particles from being infiltrated into an air cap and stuck thereon by jetting an air flow for preventing entrainment of the air flow from the circumference of an atomized air port. CONSTITUTION:Both an atomized air port 9 jetting the air for atomization and an air blowout port 10 are provided in the circumference of an atomization head. The atomized air port 9 and the air blowout port 10 are connected with an air source via the respective regulation valves and also the jetting pressure from the air blowout port 10 is regulated to <=1/5 for the jetting pressure from the atomized air port 9. In other words, levitating coating particles are prevented from being infiltrated into an air cup and stuck thereon by jetting the low-pressure air from the circumference of the air cup 6.

Description

Detailed Description of the Invention Industrial Field of Application The present invention relates to a spray gun for painting, and more specifically to a spray gun used for spraying objects having concave surfaces, or for continuous automatic painting. The present invention relates to a spray gun and a spray gun used to prevent paint from adhering to the spray gun.

<Prior Art> Generally, there are spray guns for painting that incorporate various atomization methods. The most widely used method is the ground spray method, which provides a good finish and which allows suitable painting to be applied to various shapes of objects and various types of paints.

This method has the drawback that the compressed air is mixed with the paint and atomized and sprayed onto the object to be coated at the same time, resulting in a large number of atomized paint particles being scattered due to the ejected air and the compressed air that bounces off the object. be.

Many experiments have been conducted and countermeasures have been devised in an attempt to prevent scattering. There is a method of installing an air curtain jet nozzle around the 1i air cap to wrap the paint particles and prevent them from scattering.

<Problems to be Solved by the Invention> A problem related to the scattering of paint particles is that when spraying is continued in the scattered paint particles, these scattered particles gradually adhere to the air cap surface of the spray gun. Eventually, it accumulates at the outlet of the atomizing air port, disrupting the airflow and deforming the spray particle distribution and pattern, causing paint film defects, and causing problems such as blowing away the adhered paint and staining the object to be coated. arise. In particular, in automatic painting, unlike in the case of manual painting, there is no need to pay attention to occupational safety and health considerations for suction equipment to remove scattered paint particles, and paint particles tend to fill the area around the spray gun. The surrounding air containing paint particles is easily drawn into the atomizing air ejected from the gun, increasing the amount of paint particles that stick to the paint particles. In addition, if the object to be coated has an uneven (bowl-like) shape, if the inner surface is coated, the scattered particles will return to the spray gun at a high density, resulting in large layer adhesion.For example, in the conventional example, The spray gun became unusable after about 10 minutes, and it was necessary to replace or clean it each time.

In view of the above-mentioned circumstances, the present invention provides a spraying method and a spray gun which eject airflow from the periphery of an atomizing air port to prevent entrainment of airflow (entrained airflow), and wipe away the above-mentioned defects to prevent paint from adhering. The purpose is to

Means for Solving the Problem> The spraying method for preventing paint adhesion according to the first invention includes a spray gun that jets out compressed air together with the sprayed paint to mix both fluids and atomize them. An atomizing air port that blows out air and an air jet port are provided around the atomizing head, and each atomizing air port and air jet port are connected to an air source through separate regulating valves. This is done by adjusting the ejection pressure from the outlet to 115 or less compared to the ejection pressure from the atomizing air port.

In addition, the second invention is a spray gun for carrying out the first invention, in which a paint nozzle is attached to the center of the tip of the spray gun body, with a paint passage inside and a spout formed at the tip. One or more independent passages are provided at the boundary between the paint nozzle and the main body, and the upstream side thereof is an atomizing air supply passage provided in the main body, and the downstream side is an atomizing air port of an atomizing air cap. In addition, an air jet port is provided around the atomizing air cap 2, and the atomizing air cap 2 is connected to a jetting air passage independent of the atomizing air supply path.

Due to the above-mentioned configuration, atomized paint particles are sprayed forward by the jet of atomizing air, but surrounding air is drawn into the mixed airflow and becomes an entrainment airflow. It will be done.

At this time, the air around the rear of the atomizing air gap enters through the periphery of the cap, and if there are atomized particles floating in the air, they will adhere to the air cap surface, but the spraying method of the present invention Since a low-pressure airflow is ejected forward from the outer peripheral surface of the air cap, the spray particles are drawn into this low-pressure airflow and are prevented from adhering to the air cap surface.

In addition, the spray gun in this case forms separate and independent passages in the 2M chemical air passage to eject low-pressure airflow,
This prevents paint particles floating around from being drawn in without disturbing the spray flow, and prevents paint from adhering to the surface of the air cap.

<Example> The present invention will be described below based on the drawings of the example.

The drawing shows an example of an automatic spray gun, in which a paint supply path 4a is formed in the center of the spray gun body 1, a paint nozzle 4 is provided at the rear end, and a paint supply path 4a is formed in the outer periphery of the paint nozzle 4. An air cap 6 is hinged to the cover 5. The air cap 6 is provided with a pattern forming air port 8 and an atomizing air port 9 that communicate with the pattern adjustment air supply path 7, and is provided with an air port 9 that is independent of the main body l in the gap between the air cap 6 and the cover 5 on the outer periphery of the air cap 6. An accompanying air flow blocking air outlet 1O is formed in communication with the injection air supply path 11 provided as a jet air supply path 11. in this case,
The air outlet lO may be formed on the periphery of the air cap 6 itself.

That is, the air outlet 10 has a large number of holes of 0.8 fin formed in a circumferential manner near the peripheral edge of the air cap 6 facing forward. In addition, a cover 5 is provided between the outer peripheral surface of the air cap 6 and the outer peripheral surface of the air cap 6.
This prevents leakage to the outside. Since the air pressure itself is low, leakage from the cover can be ignored, but if there is a problem, it can be stopped with a gasket.

Next, to explain the operation, first, the paint is supplied to the paint nozzle 4 by the operation of the air piston 2 and the needle valve 3 moving back appropriately.
The air is ejected from the end, atomized by the air ejected from the surrounding atomizing air ports 9, and a predetermined pattern is formed by the air ejected from the outer pattern-forming air ports 8.
Normally, the i-forming air and the pattern forming air have separate air passages, and are regulated and ejected from each other. ) The spray pressure in a normal spray gun is 3 to 3.5 kg.
/ cm'' is considered the standard, but in this case, the air pressure from the jet nozzle is approximately 0.2 to 0.3 kg/cm' (equivalent to the associated air flow generated by the air flow sprayed at a specified pressure). airflow towards the front of the cap).

Here, the atomized paint particles are sprayed forward, and the surrounding air is drawn into the mixed airflow and flows as an accompanying airflow. Since a low-pressure airflow is ejected forward from the air outlet 10, the spray particles are drawn into this low-pressure airflow and the accompanying airflow is blocked, thereby preventing paint particles from adhering to the surface of the air cap 6. become what is done.

<Effects of the Invention> As described above, the spraying method and spray gun of the present invention designed to prevent paint adhesion eject airflow from around the atomizing air port to prevent entrainment of airflow, thereby creating an atmosphere in which paint particles float. When spraying indoors, especially with an air spray gun, there is a lot of entrainment due to the accompanying air current generated by the blown air, and paint particles in the entrained air tend to adhere to the air cap, but low-pressure air from around the air cap The intrusion and adhesion of floating paint particles by jetting is eliminated. In addition, in situations where a large amount of paint mist is scattered around the gun, for example, when the gun is installed inside the device such as an automatic painting device, or even if there is a mist suction device, the spray sprayed on a concave surface may be affected by air flow. In addition, the effect is great when the painting condition is such that the spray gun is easily returned to the direction of the spray gun.In the case of painting the bowl mentioned above, even if the spray gun became unusable after about 10 minutes, with the present invention, the spray gun can be used for more than 1 hour. Continuous painting is possible, cleaning the spray gun,
This has the effect of greatly reducing replacement and work interruptions for that purpose.

[Brief explanation of the drawing]

The drawings show an embodiment of the present invention, and FIG. 1 is a sectional side view of the main part, FIG. 2 is a front view, and FIG. 3 is a sectional view of another embodiment of the air outlet for blocking the accompanying airflow. . 1. Spray gun body 0. Needle valve 0. Paint nozzle 0. Cover 9. Air gap 1. Pattern adjustment air supply path 1. Air port for pattern formation 1. Atomizing air port 1. Air outlet for blocking accompanying airflow 11°, injection air supply path

Claims (1)

[Claims] 1. In a spray gun that ejects compressed air together with spray paint to mix both fluids and atomize them, an atomizing air port that ejects the atomizing air and an atomizing head are provided. An air outlet is provided, and each atomizing air outlet and air outlet are connected to an air source through separate regulating valves, and the ejection pressure from the air outlet is adjusted to the ejection pressure from the atomizing air outlet. A spraying method for preventing paint adhesion, which is characterized by adjusting the spraying amount to 1/5 or less. 2. Attach a paint nozzle with a paint passage inside and a spout at the tip to the center of the tip of the spray gun body.
One or more independent passages are provided at the boundary between the paint nozzle and the spray gun body, and the upstream side is an atomizing air supply path provided in the spray gun body, and the downstream side is an atomizing air supply path provided in the atomizing air cap. A spray gun designed to prevent paint from adhering, which is provided with an air outlet around the atomizing air cap, and communicates with the atomizing air supply path and an independent ejection air passage.