JPH0561981B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is applicable to, for example, an automobile painting line,
The present invention relates to an automatic coating method that performs automatic painting by reciprocating a coating machine in a direction perpendicular to the direction of conveyance of an object to be coated, which is conveyed at a constant speed, at a stroke speed corresponding to the conveyance speed of the object to be coated.

[Conventional technology]

In automotive painting, reciprocators called top reciprocating and side reciprocating
Automatic painting is performed by reciprocating a coating machine at a constant speed from above and from the sides of an automobile body to be coated in a direction perpendicular to the direction of conveyance thereof.

In this case, normally the stroke speed of the paint sprayer is maintained constant according to the conveyance speed of the car body, and the stroke length of the paint sprayer is varied according to changes in the shape of the car body, while a constant spray is maintained from the paint sprayer. The paint is sprayed in the width of the pattern and layered.

By the way, FIGS. 2 a to 2 d show a coating machine having a constant spray pattern width W at different stroke speeds and a constant stroke length L in a direction perpendicular to the conveying direction of the object to be coated (as shown by arrow F). FIG. 3 is an explanatory diagram showing numerically the number of times the paint is applied during reciprocating motion.

For example, in Figure a, the stroke speed of the paint sprayer is too slow compared to the conveyance speed of the object to be painted.
This shows a case where only one coat can be applied, and in this case, in addition to the one-coat area, there are also two-coat areas and areas with gaps (zero coats) that cannot be coated at all, resulting in poor coating.

Therefore, the stroke speed of the coating machine needs to be selected to be at least a certain speed that allows multiple coatings to be applied, depending on the transport speed of the object to be coated, so as not to cause at least scratches.

[Problem that the invention seeks to solve]

However, according to the experiments and research conducted by the present inventors, when the stroke speed of the paint sprayer is set to a speed that allows three coats of paint as shown in Figure 2c, no sagging occurs, but there are two coats of paint other than the three coats. It was found that there were parts where two coats and four coats were applied, and the film thickness became extremely non-uniform. That is, it has been found that when an odd number of coats, such as one coat or three coats, are applied, coating defects are unavoidable to varying degrees.

On the other hand, as shown in FIGS. 2b and 2d, it has been found that if the coating machine is operated at a stroke speed that allows two or four coats, the film thickness becomes extremely uniform.
In other words, it has been found that coating defects can be prevented by setting the stroke speed so that the paint spray pattern is overlapped an even number of times.

However, further experiments revealed that it was not possible to form a uniform coating film over the entire surface of the object to be coated by simply setting the stroke speed of the coating machine to a constant speed that coated the coating an even number of times.

In other words, as shown in Fig. 3, when the coating width changes due to a change in the shape of the object to be coated, which is conveyed at a constant speed in the direction of arrow F, the stroke of the coating machine is simply adjusted according to the change in coating width. Merely adjusting the length sequentially such as stroke length A - stroke length B - stroke length C will result in poor coating.

This means that when the stroke speed of the paint sprayer is set to a constant speed that allows two uniform coats with stroke length A when painting the tip T of the object to be painted,
When stroke length B is used to paint the central area M with a larger coating width by making the stroke longer than stroke length A, the stroke speed is too slow and there are areas that are coated in one coat or areas where there are gaps. On the other hand, when the stroke length C is used to paint the rear end R where the stroke length is small, the stroke speed is too fast, resulting in areas requiring three or four coats.

[Means for solving problems]

Therefore, the present invention, based on the above-mentioned experimental and research results, aims to provide an automatic coating method that can apply extremely uniform coating even when the shape of the object to be coated changes. In order to achieve this objective, the stroke length of the coating machine, which is reciprocated in a direction perpendicular to the direction of conveyance of the workpiece transported at a constant speed, is determined by the stroke length of the paintwork. By varying the stroke speed of the paint sprayer according to changes in shape and at the same time changing the stroke length,
It is characterized by overlapping the paint spray pattern over the entire surface of the object to be painted a certain even number of times.

〔Example〕

Embodiments of the present invention will be specifically described below based on the drawings.

FIG. 1 is an explanatory diagram showing an example of the automatic painting method according to the present invention, in which a coating machine having a constant spray pattern width W is conveyed at a constant speed in the direction of arrow F, and the shape of the object to be coated changes. The numbers indicate the number of times the paint is applied when reciprocating with stroke lengths A, B, and C corresponding to .

That is, according to the method of the present invention, the stroke length of the coating machine is initially set to the stroke length A that matches the shape of the tip T of the object to be coated, and at the same time, the stroke speed is adjusted according to the conveyance speed of the object to be coated. Painting is started by setting the spray patterns of the paint so that they overlap, for example, twice. In other words, if the spray pattern width W of the coating machine is 40 cm, the coating machine will make one reciprocation with the stroke length A and coat the tip T twice while the object to be coated, which is transported at a constant speed, moves 40 cm. Paint at the stroke speed that is possible.

When the painting of the tip T is finished, the stroke length B is changed to a larger stroke length B that matches the shape of the center M, where the painting width is larger than that of the tip T, and at the same time it is kept constant compared to the previous stroke length A. The stroke speed is increased according to the change in the stroke length, which increases by the length, and the stroke speed is changed so that the paint spray pattern is
Also, the painting is continued by setting the speed so that the two times overlap.

That is, a coating machine with a spray pattern width W of 40 cm is used to paint the central portion M by changing the stroke speed so that it can coat twice by reciprocating with a stroke length B while the object to be coated moves 40 cm.

When the painting of the central part M is finished, the rear end R has a smaller coating width than the central part M and the tip T.
By changing the stroke length C to a smaller one that matches the shape of the stroke length C, and at the same time changing the stroke speed to become slower in accordance with the change in the stroke length, which is smaller by a certain length compared to the previous stroke length B, The stroke speed is set to such a speed that the paint spray patterns overlap twice at the rear end R.

That is, the rear end R is coated using a coating machine with a spray pattern width W of 40 cm and changing the stroke speed so that the object to be coated moves once and back with a stroke length C and coats twice while the object to be coated moves 40 cm.

In addition, in response to changes in stroke length that occur when the coating machine moves from the tip T to the center M of the object to be coated and when it moves from the center M to the rear end R,
If the stroke speed of the paint sprayer is varied every 1/2 reciprocation, the area where one coat or three coats occur can be made very small, as shown in FIG.

As a result, the surface of the object to be coated has a substantially uniform 2-color surface over the entire tip portion T, center portion M, and rear end portion R.
Two coats are applied, resulting in a uniform coating film with no scratches and significantly improved coating quality.

In addition, although the example described the case of applying two coats, the same effect can be obtained by applying a constant even number of coats, such as four coats or six coats. This is clear from the results.

〔Effect of the invention〕

As described above, the method of the present invention varies the stroke length of the coating machine according to changes in the shape of the object to be coated, and at the same time varies the stroke speed of the coating machine according to the change in stroke length. Since the paint spray pattern is overlaid over the entire surface of the object a certain even number of times, it is possible to apply an extremely uniform coating over the entire surface of the object, which was not possible before, in response to changes in the coating width of the object. It has the excellent effect of forming a film, reliably preventing coating defects, and greatly improving coating quality.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram showing an example of the method of the present invention, and FIG.
Figures a to d are explanatory diagrams showing a comparison between the state where the paint is applied an odd number of times and the state where the paint is applied an even number of times, and Figure 3 shows the state where the paint is applied an even number of times without using the method of the present invention. It is an explanatory diagram showing a state. Explanation of symbols, W... Spray pattern width, A, B,
C...Stroke length, T...Tip of the object to be coated,
M: Central part of the object to be painted, R: Rear end of the object to be painted.

Claims (1)

[Scope of Claims] 1 Automatic painting is performed by reciprocating a coating machine in a direction perpendicular to the direction of conveyance of the object to be coated, which is conveyed at a constant speed, at a stroke speed corresponding to the conveyance speed of the object to be coated. In the automatic painting method, (a) the stroke length of the coating machine is varied according to the change in the shape of the object to be painted, and (b) the stroke speed of the coating machine is varied according to the change in the stroke length, (c) An automatic painting method characterized in that the spray pattern of the paint is thereby superimposed over the entire surface of the object to be painted a certain even number of times.