JPS59206066A - Spray gun for airless painting - Google Patents

Abstract

PURPOSE:To eliminate tailing and to improve paint depositing efficiency by providing an annular air ejecting hole around a nozzle formed with two paint ejecting holes in a specific disposition. CONSTITUTION:Two paint ejecting holes 6 are formed in such a way that the axial lines thereof intersect with each other at 30-90 deg. angle at the point P within 5mm. from the aperture, and an annular air ejecting hole 17 is provided around the holes 6. When a stop valve 10 is thereupon opened, the liquid paint pressurized to a high pressure by a pump flows through a discharging port 14 into an introducing hole 3, from which the paint passes through the two holes 7 and is ejected from the aperture 8 in the form of bar-shaped paint flow (a) into air. The paint collides against each other at the point P to form a thin liquid film which is atomized by the friction with the air. The atomized paint advances while forming a sectorial ejecting pattern. The air flow (b) ejected from the hole 17 in this stage flows so as to enclose the circumference of the flow (a) like an air curtain.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an airless coating device that pressurizes liquid paint to a high pressure and injects it into the air at high speed through a small-diameter nozzle hole to atomize it by friction with the air. The present invention relates to a device in which paint streams ejected from two nozzle holes are made to collide with each other, and the paint streams are surrounded by an air stream.

Conventionally, by colliding paint streams ejected from two nozzles with each other, a coarse-grained side stream separates from the paint stream ejected from one nozzle, creating parts called tails on both sides of the paint film. An airless painting nozzle designed to prevent this from appearing as stripes on the painted surface was developed in the 3rd year of the
It is described in 85573 and is publicly known.

However, the nozzle described in this publication has a structure in which two tips with small diameter nozzle holes are adjusted and fitted so that their axes intersect with each other, inside the tip of a body branched into a figure 7 shape. Because of this, the structure is complicated and inevitably large, making it difficult to operate.Also, the distance from the front opening of the nozzle hole to the intersection is long, which causes coarse particles to separate from the paint flow before collision. Furthermore, since the intersection angle of the paint flow at the time of collision is large, ranging from 90 degrees to 1 G'O degree,
It was not put into practical use because some of the collided paint flowed back and adhered to the nozzle, dripping and staining the painted surface.

Therefore, the inventor of the present invention installed two nozzle holes reaching the nozzle holes at 511 points from the opening on the front side of the body with the introduction hole formed on the rear side.
We have developed an airless painting nozzle in which the axes intersect with each other at an angle of 30 to 90 degrees at a point within 1 m, and there is no generation of coarse particles or backflow to the nozzle side after collision, and Although it was able to produce excellent effects such as being able to make the size of the conventional single-hole nozzle comparable to that of conventional single-hole nozzles, the problem was that some of the fine particles of paint bounced off the surface to be painted and were scattered. It was confirmed that there is room for improvement.

On the other hand, to eliminate tails, pressurized air is blown into the paint flow.
A technology has been proposed that aims to promote atomization by activating the friction between the paint flow and the air, and it pressurizes the air to a high pressure of 1.5 to 2 kg/cIK. Since the paint needs to be sprayed at a high speed, it has been found that when the airflow bounces off the surface to be coated, it disturbs the paint flow and reduces the coating efficiency.

The present invention was completed against the background of the above circumstances, and an object of the present invention is to provide an airless coating spray gun that does not generate tails and has high coating efficiency.

Hereinafter, one embodiment of the present invention will be described based on the accompanying drawings.

In the figure, 1 is made of a material 4 made of cemented carbide or ceramics with excellent wear resistance, and a body 2 has a conical surface 3 on the outer periphery of the front end, and a collar 4 on the outer periphery of the rear end, introduced in the center of the rear surface. A large hole 5 is formed, and a diameter of 0.3 is formed from the introduction hole 5 to the front end surface.
The nozzle is a nozzle in which the two paint ejection holes 6.6 of 111111 are opened so that their axes intersect with each other at an angle of 60 degrees from the opening to the point 2111111. A flange 15 is connected to the tip of the gun body 11 with a gasket through two parts, and protrudes from the inner circumferential surface.
The cap 14 that is engaged with the flange 4 is attached to the gun body 11.
By aligning the inlet hole 5 with the discharge hole 13 of the on-off valve 10.
The inner surface of the tip of the gap 14 is a circular ZL surface 16, which is aligned with the conical surface 3 of the nozzle 1.
An annular air outlet 17 is formed between the collar 15 and several ventilation holes 18 are provided through the collar 15.
A pressurized air supply 3-picture card 19 formed in the gun body 11 communicates with the air jet hole 17, and the pressurized air supply hole 19 has an on-off valve (not shown) that operates in conjunction with the on-off valve 10. Intervention is provided.

When the on-off valve 10 opens, liquid paint pressurized to high pressure by a pump (not shown) flows into the introduction hole 3 from the discharge hole 14, passes through the two nozzle holes 7.7, and enters the opening 8.
From 8, it becomes a rod-shaped paint stream a and is ejected into the air, collides with each other at point P to form a thin liquid film, and then becomes atomized by friction with the air and advances while expanding in width in a fan-shaped spray pattern. At the same time, the air jetted out from the air jet hole 17 flows to surround the paint flow a. This air flow does not collide with the paint flow a to promote atomization, but rather forms an air curtain to prevent the particles separated from the paint flow a from scattering, so the ejection pressure is 0.
5-1. A low pressure of kg/c+IT is required, so it does not bounce off the surface to be painted and disturb the paint flow.

When a liquid paint with a viscosity of 100 cps was sprayed at a pressure of 100 kg/cJ using the nozzle of this example, the paint particles were distributed in the range of 10 to 50 microns.
It was confirmed that the particles were atomized well.

Furthermore, the coating rate of the paint was extremely high at 95%.

Although it varies depending on conditions such as the viscosity of the paint used,
For good atomization, the diameter of the paint injection hole 6.6 should be 0.
．． It was confirmed that 0.05 to 0.5 mm is optimal.

In addition, if the opening of the paint injection hole 6.6 from point P to point P is too long, large particles of 100 microns or more will separate from the ejected rod-shaped liquid column, and these coarse particles will Even if they collide with each other, they do not become atomized and are directly applied to the object to be painted, resulting in a rough painted surface. Therefore, the distance from the opening of the paint injection hole 6.6 to the point P must be 511811 or less. Furthermore, the larger the intersection angle between the axes of the paint ejection holes 6.6, the more violent the collisions will be, promoting particulate matter, and the larger the spread angle of the fan-shaped paint flow after the collision, but if it is too wide, the backflow will occur. This causes paint to adhere to nozzle 1, so
It has been experimentally confirmed that a range of 0 degrees to 90 degrees is preferable.

As specifically explained in the above embodiment, the airless painting spray gun of the present invention has an introduction hole communicating with the paint supply path on the rear surface of the body, and two paint ejection holes reaching the introduction hole on the front surface of the body. An annular air jet hole is provided around a nozzle whose axes intersect with each other at an angle of 30 degrees to 90 degrees at a point within 5 nm from the opening, and the paint flow jetted from the paint jet hole is The gist of this system is to surround it with the airflow ejected from the air nozzle. Immediately after ejecting from the nozzle, the rod-shaped paint streams collide with each other in a state in which coarse particles are not ejected. Good atomization is achieved without producing particles, and the nozzle can be made to the same size as a single-hole nozzle, making it possible to reduce the size and weight, improve operability, and improve paint quality. Surround the flow with an air flow, and the air flow only needs to be extremely gentle.
It does not disturb the paint flow due to rebound, and has the effect of significantly improving coating efficiency.

[Brief explanation of drawings]

FIG. 1 is a sectional view of an embodiment of the present invention, FIG. 2 is a sectional view taken along the line A to FIG. 1, and FIG. 3 is a front view. 1: Nozzle 2: Body 5: Introduction hole 6: Paint injection hole 17: Air injection hole P: Intersection applicant Asahi Okuma Sangyo Co., Ltd. agent Patent attorney Hiroshi Noguchi 7-

Claims (1)

[Claims] On the front side of the body, which has an introduction hole that communicates with the paint supply path on the rear surface, install two paint injection holes that reach the introduction hole at a point within 5Ill'l1 from the opening, with their axes at an angle of 30 degrees to 90 degrees. An airless device characterized in that an annular air ejection hole is provided around nozzles formed to intersect with each other, and a paint flow ejected from the paint ejection hole is surrounded by an air flow ejected from the air ejection hole. spray gun for painting