JPS59147670A - Painting method by airless spray - Google Patents

Abstract

PURPOSE:To eliminate tailing and to perform vignette painting in the end part of a spray pattern by ejecting air from the side of the flow of the paint to be sprayed from an airless spray gun just in front of a material to be coated. CONSTITUTION:A pressurized paint is ejected from the spray nozzle of an airless spray gun 5 and at the same time, working air is also ejected from the nozzle 12 of an air blow 10 so as to cross the flow of the paint just in front of a material 1 to be painted. An influence of cross air is given to the particles of the paint having a decreased velocity to scatter the particles and to annihilate the tailing 4 in the end part of a spray pattern 3, thereby accomplishing vignette painting.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improved airless spray coating method in which the paint itself is pressurized and sprayed in the form of a mist. More particularly, the present invention relates to improvements in airless spray coating methods designed to eliminate tails.

Airless spray painting aims to atomize the paint by pressurizing and ejecting the paint itself without using atomizing air, so it has the advantage of significantly superior coating efficiency and efficient pressure coating. However, on the other hand, it is known that there is a problem with tails due to the nozzle of the spray gun. In other words, this tail is a phenomenon in which the spray pattern becomes cat's-eye-shaped and the film thickness becomes thicker at the edges of the cat's-eye, which is particularly noticeable when spraying high-viscosity paint.

Therefore, in the conventional airless spray coating method, as shown in FIG. was prevented from appearing. However, according to this coating method, the paint sprayed on the baffle plate 2 eventually accumulates and hangs down on the lower edge of the baffle plate 2, so that it is blown off by the paint jetted from the spray gun 5 and adheres to the object 1 to be coated. There's a problem.

This invention was made by focusing on such conventional problems, and aims to provide an airless spray painting method that can remove the tail without using a baffle plate. By spraying air from the side just before the object to be coated, the tail disappears and the edges of the spray pattern are blurred.

The present invention will be explained in detail below based on a specific device shown in the drawings.

FIG. 2 shows a front view of an embodiment of a spray gun for carrying out the airless spray coating method of the present invention.

This spray gun 5 is an automatic gun for automatic painting, and is supported by an arm 6 of a painting robot. The spray gun 5 contains paint pressurized by a paint pressure pump (not shown) and controlled to a constant pressure;
Actuating air for actuating the needle 7 of the spray nozzle is supplied via a paint hose 8 and an air hose 9. Therefore, since the paint is constantly supplied to the spray nozzle under constant pressure, the paint is sprayed out in the form of mist simply by retracting the needle 7 and opening the spray nozzle. Here, although not shown, the needle 7 is provided so as to be interlocked with a diaphragm or a piston that is actuated by a change in the pressure of working air, so it is moved backward by supplying working air from the air hose 9. Further, in order to close the spray nozzle at the same time as stopping the supply of working air, the needle 7 has a built-in restoring means such as a return spring and tends to always close the spray nozzle. Further, the spray gun 5 is provided with an air blower 10 in front of the spray gun 5, which blows air across the flow of paint blown out from the spray gun 5.

This air blow 10 is provided so that air is guided from an air hose 11 and ejected from a nozzle 12. Further, the air in the air blow 100 is controlled by a valve 13 that controls operating air in conjunction with the control of the spray gun 5. Therefore, at the same time as paint is ejected from the spray gun 5, air is also ejected from the nozzle 12 of the air blow 10. is blown out, and the air stops at the same time as the paint stops blowing out.

According to the spray gun configured as described above, when working air is supplied, the needle 7 is pulled and paint pressurized to a constant pressure is blown out from the spray nozzle, and at the same time working air is also supplied from the air blow 10. It is ejected and sprayed across the paint stream. The paint immediately before the object to be coated 1 has a lower velocity than immediately after ejection and is more susceptible to the influence of wind, so it is scattered by the working air ejected from the side air blower 10, eliminating the tail and creating a blurred coating. becomes. Here, the speed and amount of air ejected from the air blower 10 must be at a minimum enough to scatter the flow of paint to the extent that the tail on the upper end side of the spray pattern 3 disappears.

As is clear from the above description, the present invention sprays air from the side just before the object in the flow of paint from the airless spray gun toward the object. is scattered and the tail disappears. However, since air is blown from a direction substantially perpendicular to the direction of paint travel just before the object to be coated to attenuate the velocity energy of the paint at the edge of the pattern, Prevents paint mist from scattering.

[Brief explanation of the drawing]

FIG. 1 is a front view of a spray gun that performs the conventional airless spray coating method, and FIG. 2 is a front view of a spray gun that implements the airless spray coating method of the present invention. 1...Object to be coated, 3...Painting pattern, 4...Tail, 5...Spray gun, 10...Air blower. Patent applicant Nissan Motor Co., Ltd.

Claims (1)

[Claims] In the airless spray painting method, in which the paint itself is pressurized and ejected in the form of a mist, air is sprayed from the side of the spray pattern just before the object as the paint flows from the spray gun toward the object, eliminating the tail and spraying. An airless spray painting method characterized by shading the edges of the pattern.