JPS61268380A - Atomizing painting method - Google Patents

Abstract

PURPOSE:To form a smooth and uniform paint film having no painting flaw, by setting the spray head of an atomizing painting apparatus so as to always provide a constant distance with respect to a surface to be painted and relatively moving the spray head and an article to be painted so as not to overlap painting patterns. CONSTITUTION:The car body 2 mounted to a truck 1 is automatically fed into a booth at a constant speed by a conveyor and, when the leading end part C of the body reached the position on the center extended line of the spray head 4 of the rotary atomizing electrostatic painting apparatus 3 arranged in the booth, the spraying of the paint from the spray head is started. The painting pattern A' of a paint is preliminarily programmed so that the upper end part thereof always corresponds to the boundary line of the outside panel 5 of the body 2 and a hood 6 and the distance between the spray head 4 and the outside panel 5 is made constant. The spray head 4 is controlled in its movement through air cylinders 8, 9 so as to follow the painting pattern A'.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The disclosed technology belongs to the field of atomization coating technology for automatically conveyed objects to be coated.

Therefore, this invention relates to a method for atomizing an object to be coated which is automatically conveyed by a conveyor or the like and moves relative to an atomizing coating device such as a rotary atomizing electrostatic coating device over time, In particular, the spray head of the atomization coating device is always kept at a constant distance from the surface to be coated of the object to be coated, and the spray head and the object to be coated are moved relative to each other so that the coating patterns do not overlap with each other. This invention relates to an atomization coating method.

<Prior art> As is well known, when painting a large number of objects of the same shape under the same finishing conditions, such as painting the bodies of automobiles in an automobile manufacturing factory, it is necessary to paint the objects in a booth. is automatically conveyed by a conveyor, and is automatically carried out using an atomization coating device such as an air atomization electrostatic coating device or a rotary atomization electrostatic coating device installed in the booth.

Conventionally, when painting the outside panel of a car, for example, as shown in FIG. On the other hand, paint is sprayed from the fixed spray head 4 of the atomization coating device 3 installed in the booth onto the outer panel 5 as the surface to be coated, thereby performing the coating process.

In addition, as for other conventional painting methods,
As disclosed in Publication No. 23 or Japanese Patent Publication No. 59-21670, when painting the outside panel of an automobile,
The spray head is moved up and down along the guide pole of the atomization coating device, and the coating process is performed by meandering relative to the outer panel of the body that is automatically transported.

<Problems to be solved by the invention> However, in the above-mentioned conventional atomization coating method, the third
As in the case of the conventional example shown in the figure, when painting the boundary between the outer plate 5 and the hood 6, the trajectory of the center of the spray head 4 relative to the outer plate 5 is as shown by the dashed line a in the figure. The coating pattern is shown in the hatched area A in the figure.

As a result, the paint particles sprayed from the spray head 4 are oversprayed onto the hood 6, and at the same time as the outer panel 5 is being painted, the paint particles are being oversprayed onto the hood 6, which is being painted by another atomization coating device.
Coupled with the painting process, an overcoated area B is formed over a width of 100 mm or more, as shown by hatching in Figure 4,
As shown in Figure 6, the coating film structure of the overcoated area B is formed by a wet coating layer C applied by a predetermined coating machine and an oversprayed high viscosity layer, and is a painted surface that is not recoated. The viscosity of the wet coating film was different from that of C', and there was a drawback that a uniform and smooth surface could not be obtained.

This is because the floating distance of the overspray paint particles to the surface to be coated of the hood 6 becomes longer, so the volatilization of the solvent in the paint particles increases, and the wetness of the overspray paint particles to the hood 6 by the above-mentioned atomization coating device increases. This is because when it lands on the coating surface, a highly viscous coating layer is formed and it cannot be dissolved in the wet coating.

In addition, Figure 5 shows the relationship between the smoothness of the paint film and the paint film thickness when the ratio λ of the film thickness due to overspray paint particles and the set topcoat film thickness (hereinafter referred to as overspray ratio) is used as a parameter. This shows a relationship, and regardless of the film thickness, the smaller the overspray ratio, the better the smoothness.

Furthermore, in the conventional atomization coating method, the spray head is reciprocated in one direction, so it is difficult to coat objects that have a curved surface over the front part of the vehicle, such as the body 2 of a car. Another drawback was that the distance between the painted surface and the spray head changed over time, making it impossible to obtain a uniform film thickness.

The purpose of this invention is to solve the problems of the atomization coating method based on the above-mentioned prior art, and to make it possible to form a coated surface with a uniform thickness without coating defects.
It is an object of this invention to provide an excellent atomization coating method that is useful in the field of application of coating technology in various manufacturing industries.

<Means/effects for solving the problems> In order to solve the above-mentioned problems, the structure of the present invention, which is based on the above-mentioned claims, is to solve the above-mentioned problems. The spray head and the object to be painted are always kept at a constant distance from the surface to be painted, and the spray head and the object to be painted are moved relative to each other so that each painting pattern does not overlap with each other, so that the paint particles sprayed from the spray head are The amount of solvent volatilized from each particle during landing on the surface to be painted is almost the same, so that there is no difference in the viscosity of each particle, and overspray on each surface to be painted is minimized. Technical measures have been taken to form a smooth coating film with no coating defects and a uniform thickness.

<Embodiment> Next, an embodiment of the present invention will be described below with reference to FIG. 1.2. Note that the same parts as in FIG. 1 will be explained using the same reference numerals.

The embodiment shown in FIG. 1 is an automobile body 2 as an object to be coated.
The outside plate 5 of the body 5 is painted by a rotary atomizing electrostatic coating device @3 as an atomizing coating device, and the body 2 placed on the trolley 1 is conveyed at a constant speed into the booth by a conveyor (not shown). When the tip C of the body 2 reaches the central extension line of the spray head 4 of the rotary atomizing electrostatic coating device 3 installed in the booth, spraying of paint starts from the spray head 4. do.

The rotary atomizing electrostatic coating device 3 is connected to a servo-mechanism type air cylinder 8 supported by a fixed base 7, and another servo-mechanism type air cylinder 9 supported by the air cylinder 8.
can be moved up and down within a range of 200 mm, and the spray head 4 supported by the air cylinder 9 can be moved horizontally within a range of 100 to 350 mm. is programmed and controlled in advance so that the upper end of the coating pattern A' sprayed from the spray head 4 always corresponds to the boundary line between the outer plate 5 and the hood 6 of the body 2, while the air cylinder 9 The horizontal movement of is programmed and controlled in advance so that the distance between the spray head 4 and the outer plate 5 is constant, corresponding to the curved surface of the outer plate 5 along the direction of movement of the body 2.

Therefore, the trajectory of the center of the spray head 4 with respect to the outer plate 5 becomes like the dashed line a' shown in FIG. This is suppressed to a minimum, over-coating is prevented, and a coating film of uniform thickness can be formed even at the boundary between the outer plate 5 and the hood 6.

Furthermore, since the distance between the spray head 4 and the outer plate 5 is always maintained at a set distance, the spray paint particles land on the surface to be painted with a constant viscosity, and as a result, the coating of the paint particles is reduced. Efficiency is improved, the smoothness of the coating film is improved, and coating defects such as local coating defects or gloss defects are no longer caused, and the accuracy of coating finish can be improved.

In this example, in order to prevent overspray paint particles from floating, the descending wind speed in the booth was set to 0.4 to 0.0.2%, which is higher than the conventional wind speed of 0.2 to 0.3111/S.
It is set at 6 m/s.

Other Embodiments> It goes without saying that the embodiments of the present invention are not limited to the above-mentioned embodiments. For example, the atomization coating device may be an air atomization electrostatic coating device, or an air atomization coating device may be used. , an airless atomization coating device, etc., and the means for moving the spray head may be a hydraulic cylinder, an electric cylinder, etc. Various embodiments can be adopted.

<Effects of the Invention> As described above, according to the present invention, the spray head of the atomization coating device is always kept at a constant distance from the surface of the object to be coated, and the above-mentioned arrangement is made such that each coating pattern does not overlap with each other. By moving the spray head and the object to be coated relative to each other, overspray can be minimized and over-coating can be prevented.Furthermore, when spray paint particles land on the surface to be coated, It has the excellent effect of keeping the viscosity constant and improving the smoothness of the coating film.

Therefore, it is possible to form a coating film with extremely good smoothness and uniform thickness over the entire surface of the object to be coated, which has the excellent effect of improving the precision of the coating finish. is played.

[Brief explanation of the drawing]

Figures 1 and 2 show one embodiment of the present invention, Figure 1 is a side view of the painting process, Figure 2 is a rear view of the same, and Figures 3 and below are based on the prior art. Fig. 3 is a side view of the conventional technique equivalent to Fig. 1, Fig. 4 is a reduced plan view of the same, Fig. 5 is a graph showing the correlation between smoothness and film thickness, and Fig. 6 is a coating film according to the conventional technique. FIG. 3...Atomization coating device, 2...Object to be coated, 4...
Spray head, tail...surface to be painted, A'...painting pattern

Claims (1)

[Claims] In a method of atomizing coating an object that moves relative to an atomizing coating device over time, the spray head of the atomizing coating device is always kept at a constant distance from the surface of the object to be coated. An atomization coating method characterized in that the spray head and the object to be coated are moved relative to each other so that the patterns do not overlap each other.