JPH0361505B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an air cap for an air spray gun, and more particularly to a side air port that forms a stable spray pattern suitable for painting a spray stream of paint atomized by compressed air. This relates to an air cap having a

Conventionally, as shown in FIG. 1, the air cap of a general air spray gun has a paint nozzle 12 with a paint spout 11 in the center, and a paint nozzle 12 located on the outer periphery of the paint spout 11 of the paint nozzle 12. By jetting out compressed air from the central air port 13, the paint is atomized and a spray stream is formed. Furthermore, in order to accommodate various painting conditions such as various objects, paints, and finishing conditions, the spray pattern is shaped into an oval shape suitable for painting by colliding compressed air flow from the air ports 14 on both sides with the spray flow from the center. Or it is deformed into an oval shape.

However, as the spray pattern becomes larger, simply colliding a simple circular jet from the side air vents with the central spray will constrict only the collision area, making it impossible to form a spray pattern with uniform density. Therefore, by once colliding with the jet from the auxiliary air port 15 coming from near the center air port, the circular jet from the side air port 14 is flattened and collided with the center spray flow. For this reason, in addition to the central air vent, the air cap has side air vents and auxiliary air vents.
This increases the number of holes, necessitates complex and accurate hole machining, and requires a large number of machining steps, resulting in difficult manufacturing and unstable patterns. Moreover, the spray pattern must be checked even after processing, which poses a problem in mass production and lower production costs.

Furthermore, the reason why various air ports are used to stabilize the pattern is to make the combined air flow into an appropriate flat air pattern, but because of the composite flow, not only does the pattern itself lack stability, The forward spray speed is accelerated by the forward jet from the auxiliary air vents located around the central air vent, and the spray itself gives the worker a hard feeling, giving the impression that the work is difficult. I was getting used to it.

In view of the above-mentioned circumstances, the present invention provides a side air port with an irregular opening shape to eject a flat jet from the beginning, stably forming a uniform spray pattern, and achieving high atomization efficiency. The purpose is to provide an air cap that can obtain a spray condition suitable for painting (forming a smooth painted surface), and another purpose is to simplify the processing of the air port of the air cap. The purpose is to reduce man-hours, reduce defect rates and production costs, and provide an air cap suitable for mass production.Another purpose is to eliminate auxiliary air ports, which will reduce the speed of spraying. The purpose is to provide an air cap that obtains a spray flow with a soft feel suitable for.

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

Reference numeral 1 denotes a paint nozzle provided at the tip of a needle valve 3 placed in the center of the gun body 2. The paint nozzle 1 introduces paint from the rear, and has a paint spout 4 at its tip.
is provided. Further, a central air opening 7 consisting of an annular slit is formed between the outer periphery of the tip of the paint nozzle 1 and a central hole 6 of an air cap 5 disposed on the outside thereof. In addition to the central air port 7, the air cap 5 has side air holes 8, which are a pair of single holes for forming a spray pattern that collide with each other on the axis of the paint nozzle 1 and in front of the paint nozzle 4. It has 8. The side air ports 8, 8 have opening shapes that are symmetrical with respect to a plane that is common to the center line with the center air port 7, and are asymmetrical with respect to other lines and planes, and the side air ports 8, As shown in Fig. 5 A, B, and C, 8 is a substantially crescent-shaped, inverted triangular, dish with a substantially flat irregular shape and a bulge 8a on the side closer to 7 (indicated by the arrow in the figure) at the central air opening. shape, a circle such as a V-shape, and an irregular shape other than a rectangle. 9 is a paint inlet, and 10 is an air passage.

Next, the operation of the present invention will be described. First, paint is introduced into the paint nozzle 1 through the paint introduction port 9, and is ejected from the paint spout 4 at the center of the tip of the paint nozzle 1 when the needle valve 3 retreats. On the other hand, compressed air is injected through the air passage 10 from the central air port 7, which is an annular slit formed between the central hole 6 of the air cap 5 and the paint nozzle 1.
A spray stream of fine paint particles is formed by collision and diffusion against the paint jetted from the paint spout 4. Furthermore, the compressed air is at the tip of the air cap 5,
It is injected from a pair of side air ports 8, 8 that collide in front of the paint spout 4, and collides with the spray flow from the center from both sides to flatten the spray flow, forming an oval shape or an oval shape suitable for painting. Forms an oval spray pattern.

In this case, the side air ports 8, 8 are the center air ports 7.
The opening shape is symmetrical only with respect to a plane that is common to the center line of the air vent 7, and is formed in a substantially flat irregular shape other than a circular or square shape with a bulge 8a on the side closer to the central air port 7. Because of this, the jet of compressed air injected from the side air ports 8, 8 becomes flat from the beginning and collides with the spray from the center. Moreover, since the side air ports 8, 8 have a bulge 8a on the side closer to the center, the spray stream collides with the spray stream at a portion that gradually widens from the center. That is, the spray stream at the center is first spread out in the narrow width part of the air injection pattern (air pattern), and the slightly wider part of the air pattern collides with the spray stream. For this reason,
Since a suitably wide air stream can be used at each impingement stage, stable atomization and efficient atomization are achieved.

As described above, the present invention forms the paint jetted from the paint jetting port into an atomized spray stream by jetting compressed air from the central air port, and also aligns the side air port to the center line with the central air port. By creating an irregular shape that is substantially flat other than a circular or square shape that is symmetrical only with respect to a common plane, and by forming a bulge on the side closer to the center air hole by forming the opening shape of the side air hole, The jet of compressed air from the side air vents is flat from the beginning, and the side air vents have a bulge on the side closer to the center. This allows for stable atomization and efficient atomization without causing defective patterns, and it is possible to obtain a spray pattern suitable for painting. In other words, compared to the conventional case of combining various air flows from a plurality of auxiliary air ports and the circular openings of the side air ports to form the air flow for pattern formation, it is possible to create the desired air flow using only a pair of side air ports. can be formed,
Since it is not a synthetic flow, there is no wasted airflow and atomization is improved. Furthermore, the collision angle of the airflow from the side air vents is obtuse compared to the conventional composite flow, and the spray flow is not accelerated by the auxiliary air vents, so the particle velocity is low and the mist is soft, making it easier for workers to paint. This is an easy pattern to do.

Moreover, since only the pair of irregularly shaped side air ports need to be machined into the air cap, the hole machining is simplified and the number of machining steps can be reduced accordingly, making the air cap suitable for mass production. .

[Brief explanation of drawings]

1 and 2 are a sectional view and a perspective view of a conventional air cap. Figures 3 to 5 show embodiments of the present invention; Figure 3 is a sectional view, Figure 4 is a perspective view, and Figures 5A, 2B, and 5 are illustrations of the side air vents seen from the front. It is a diagram. 1... Paint nozzle, 4... Paint spout, 5...
Air cap, 7...center air vent, 8...side air vent, 8a...bulge.

Claims (1)

[Scope of Claims] 1. For a paint nozzle having a paint nozzle at the center, an annular central air port is formed around the nozzle, and the air flow crosses and collides with the spray stream in front of the nozzle. In a spray gun having side air ports arranged in opposite positions such that An air cap for a spray gun characterized by being formed in an opening shape so as to emit a flat air stream. 2. The air cap for a spray gun according to claim 1, wherein the side air port has an irregular opening shape that is substantially flat and has a bulge on the side closer to the paint spout.