JP2636353B2 - Painting method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial application field) The present invention relates to a coating method.

(Prior Art) When an object to be coated, for example, an outer surface of an automobile body is applied by spraying, a preparation step for removing dust adhering to the object to be coated, and a step of spray-coating the object with the coating, Drying the applied paint. This drying step is generally performed in two stages, a setting step and a baking step, and the setting step is performed before the baking step at a lower temperature than the baking step, for example, at room temperature or 40 ° C. It is performed in a temperature atmosphere of 60 ° C. (the baking temperature in the baking process is usually around 140 ° C.).

The object to be coated usually undergoes the above-described preparation step, coating step, and drying step while being conveyed by a conveying means such as a cart, but the posture of the object to be coated is maintained at a predetermined position in each step. It is being done as it is.

By the way, as one criterion for evaluating the quality of a painted surface, there is smoothness (flatness). The greater the smoothness, the smaller the degree of unevenness of the painted surface, and the better the painted surface. It is already known that the smoothness of the painted surface can be improved by increasing the thickness of the coating film, that is, the thickness of the applied paint.

On the other hand, there is a "drip" of the paint as an obstacle to the quality of the painted surface. This dripping is caused by the paint applied by flowing under the gravity and flows largely up and down. As the film thickness of the paint applied at one time is larger, the dripping easily occurs. The cause of the dripping is as follows. After all, because of the influence of gravity, the surface of the object to be coated tends to occur on a surface extending in the vertical direction, that is, a so-called vertical surface. For example, when considering the body of an automobile as an object to be coated, sagging is not likely to occur on a hood or a trunk lid serving as a lateral surface, but sagging tends to occur on a fender serving as an upright surface.

Therefore, the thickness of the coating material to be applied to the surface extending in the horizontal direction, that is, the so-called horizontal surface, of the object to be coated on which the “sagging” of the coating does not become a problem can be made larger than the vertical surface. Even if the thickness of the coating on the horizontal surface is the same as the thickness of the coating on the vertical surface, the unevenness is reduced by a slight flow of paint that does not cause dripping on the horizontal surface, and the vertical surface is smooth. The degree of smoothness better than the degree is obtained.

From the viewpoints described above, in the past, in order to obtain a painted surface with as large a smoothness as possible while preventing "sagging" of the paint, it has been attempted to apply the paint using a paint with low fluidity (small viscosity) as much as possible. I was The so-called "sagging limit" at which "sagging" of the paint occurs on the vertical surface was about 40 [mu] m in the thickness of the coating film of the conventional thermosetting paint. More specifically, the “sag” of the thermosetting paint is likely to occur at the beginning of the setting step and at the beginning of the baking step, particularly at the beginning of the baking step, and is applied in the painting step so that “sag” does not occur at this time. The thickness of the paint is determined, and the maximum value of the determined thickness, that is, the sag limit value is about 40 μm. Therefore, in order to obtain a coated surface having a greater smoothness absolutely, the conventional coating method requires, for example, two coatings.
A series of steps from the painting step to the baking step had to be repeated a plurality of times.

(Problems to be Solved by the Invention) Overcoming the sagging limit, which is a problem when coating by spraying as described above, a coated surface with better smoothness can be obtained if the coating thickness is the same. Applicants have developed a coating method that can be obtained. That is, while the thickness of the coating film when applying the paint by spraying is set to a thickness equal to or more than the sagging limit, the object to be applied is rotated about a substantially horizontal axis until the applied paint is cured until sagging does not occur. We developed a painting method that can be rotated. According to this painting method,
The direction of gravity acting on the paint is changed by the rotation of the object to prevent dripping, while actively utilizing the large fluidity of the paint, making it smoother if the thickness of the coating is the same An excellent painted surface can be obtained.

However, when the above-mentioned coating method is carried out, the paint tends to concentrate on the corner where the horizontal surface and the upright face continue, and after the paint is dried, the paint surface of this corner partially rises considerably considerably. Turns out to be problematic. In particular, when the paint is sprayed on the horizontal surface and the paint is sprayed on the vertical surface, the paint is conventionally sprayed from both directions at the corners (overspray), and the coating film is originally thicker. It tends to be easy.

In particular, the boundary portion near the vertical surface of the lateral surface is important from the viewpoint of appearance, and it is a problem how to prevent the partial rise of the coating film at the boundary portion.

Therefore, an object of the present invention is to provide a coating method utilizing the above-described dripping limit or more of the paint spraying and the rotation of the object to be coated about a substantially horizontal axis, wherein the coating film at the boundary portion near the vertical surface of the horizontal surface is provided. An object of the present invention is to provide a coating method capable of preventing swelling.

(Means and Actions for Solving the Problems) In order to achieve the above object, the present invention has the following configuration. That is, a coating step of applying a paint by spraying on a lateral surface extending in a lateral direction and a vertical surface extending in a vertical direction of the object to be coated,
A drying step of drying the applied paint, wherein the spraying of the paint on the lateral surface is performed so that a boundary portion of the lateral surface which is a portion near the upright surface is thin and other than the boundary portion. The other portion is performed so as to have a thickness equal to or greater than the sag limit. The spraying of the paint on the upright surface is performed so as to have a thickness equal to or greater than the sag limit. The object to be coated is rotated about a substantially horizontal axis until the paint is cured until no dripping occurs.

As described above, in the present invention, the direction of gravity acting on the paint applied to the workpiece is changed by rotating the workpiece about a substantially horizontal axis. It will be dried without occurring.

According to the present invention, it is possible to obtain a very good painted surface whose smoothness far exceeds the level which has been conventionally regarded as the limit by making the thickness of the coating applied at one time much thicker than before. it can.

Also, even if the thickness of the coating film is the same as before,
By utilizing the fluidity of the paint, it is possible to obtain an excellent painted surface having less unevenness, that is, a greater smoothness.

Furthermore, if it is intended to obtain a coated surface having the same smoothness, for example, the same smoothness as that obtained by a conventional coating method, the thickness of the paint to be applied can be made thinner than the conventional one, The amount of paint used can be reduced by the amount that can be made thinner.

Then, in the present invention, when the paint is sprayed on the lateral surface, the boundary portion is formed on the other side of the lateral surface with respect to the boundary near the vertical surface of the lateral surface where the partial swelling of the paint is a problem. Because it is made thinner than the part, even if it receives overspray by spraying paint on the elevation, it prevents the situation where this boundary part becomes extremely thick with respect to other parts of the side surface Is done. As a result, the thickness of the coating film at the boundary portion obtained after the paint is dried is the same as or slightly thicker than the other portion of the lateral surface, which is preferable in appearance. Of course, the fact that the boundary portion does not become too thick is preferable in that not only the amount of paint used is reduced, but also the time for rotating the object to be coated can be shortened as much as possible.

Either the spraying of the paint on the lateral surface or the spraying of the paint on the vertical surface may be performed first, or they may be performed simultaneously. However, since the lateral surface has more time before sagging than the vertical surface,
It is preferred that the spraying on the lateral surface is performed to the left.

Here, the spraying of the paint may be spraying by electrostatic painting. In addition, the dripping of the paint means the movement of the paint that can be visually confirmed when the paint is left in a sprayed state (appears as a streak when the paint is cured),
Generally, it is assumed that dripping occurs when the movement of the paint by about 2 mm is confirmed. Therefore, spraying paint to a thickness greater than the sag limit means that the paint will move at least about 2 mm if left as it is, and the greater the fluidity of the paint used, the greater the sag The marginal thickness becomes smaller. In order to make the thickness equal to or more than the sagging limit, the spraying may be performed by one spraying (one stage blowing), and the thickness may be finally equal to or more than the sagging limit by two or three or more sprayings ( Multistage blowing). Furthermore, the rotation of the object to be coated about the substantially horizontal axis is
Since it is only necessary to prevent a large movement of the paint due to the action of gravity, the paint is continuously moved in a predetermined direction until the paint does not have a large flow state that causes dripping, that is, until the paint is hardened. The rotation may be performed continuously or intermittently, or the forward and reverse rotations may be performed continuously or intermittently. As the rotation angle range of the object to be coated, it is sufficient that the direction in which gravity acts on any part where the paint is sprayed to the thickness above the sag limit is reversed, and 270 ° is sufficient. . The rotation axis of the object to be coated may be inclined at an angle of about 30 degrees with respect to the true horizontal axis, and the rotation axis may be swung.

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

Overview of Overall FIG. 1 shows the overall steps in the case of coating an automobile body W as an object to be coated, and the steps are indicated by P1 to P4.

First, the body W, for which undercoating has been completed as is known by electrodeposition coating, is sent to the preparation process P1 while being held by the carriage D. In the preparation process P1, dust inside and outside the body W is removed by, for example, air blow or vacuum suction. Thereafter, in step P2, paint is sprayed on the body W. Then, the paint is dried in the setting step P3 and the baking step P4.

When the processes P1 to P4 are for intermediate coating, after the process P4, the body W is sent to the process for top coating. In addition, steps P1 to P4
Is for overcoating, the body W is transported to the assembly line in a known manner.

Dust Removal The dust removal in the process P1 may be performed while rotating the body W around the horizontal axis l, as shown in FIG. That is, for example, first, after the rotation of the body W is stopped in the state shown in FIG. 2A to remove dust, the posture of the body W is changed to the state shown in FIG. It stops at the position and the dust is removed again. In this way,
As shown in (c), (d), (i) of FIG. 2, dust is removed while the body W is intermittently rotated.

As described above, by removing the dust while rotating the body W, the dust adhered to the inside of the closed section such as the inner corner of the roof panel or the side sill of the body W, that is, the body W must be rotated. It is possible to completely remove dust that does not fall.

Spraying and drying of paint First, spraying of paint at P2 is performed so that the thickness of the coating film is equal to or greater than the sag limit. That is, in the paint generally used in the past, the maximum thickness of the paint that does not cause “sag”, that is, the sag limit value is about 40 μm, but in the process P2, the coating film is much thicker than the sag limit of 40 μm. (For example, 65 μm). Of course, the dripping limit film thickness can be made sufficiently small, for example, 30 μm or the like (adjustment of the content of the solvent or the anti-sagging agent). It does not become.

The details of the spraying of the coating in the coating step P2 will be described later.

In the setting step P3, the body W is rotated in the horizontal direction as shown in FIGS. 2 (a) to 2 (i). That is, the body W is rotated about a rotation axis l extending in the horizontal direction. In the embodiment, the rotation axis l is
It extends in the front-rear direction. The temperature atmosphere in the setting step P3 is normal temperature in the embodiment, but may be set to an appropriate temperature within a range of a temperature lower than the temperature atmosphere in the next baking step P5, such as 40 ° C. to 60 ° C. Of course, this setting step P3 is for preliminarily evaporating the low-boiling components in the paint, thereby causing pinholes on the painted surface due to rapid volatilization of the low-boiling components in the next baking step P5. Is prevented.

In the baking step P4, for example, the paint is baked in a 140 ° C. temperature atmosphere. In this P4, as in the setting step of P3, the body W is rotated in the horizontal direction as shown in FIGS.

Due to the horizontal rotation of the body W at P3 and P4 described above, the paint is dried without dripping even if the paint is sprayed to a thickness greater than the sag limit at P2. As a result, a high-quality coated surface having extremely high smoothness, which cannot be obtained by the conventional coating method, can be obtained.

Relationship between coating film thickness, sag limit, smoothness, and horizontal rotation FIG. 3 shows the effect of the film thickness on the sag limit. In FIG. 3, the coating thickness is 40
The three cases of μm, 53 μm and 65 μm are shown. It is understood that, in any of these thicknesses, a "drip" peak occurs both at the beginning of the setting step and at the beginning of the printing step. Also, the dripping limit is usually 1 per minute.
~ 2mm is the value when sagging occurs (2mm /
If the sagging of more than a minute occurs, the coated surface is considered to be defective), and the maximum coating thickness obtained in the range below the sagging limit is about 40 μm with a conventional paint.

On the other hand, FIG. 4 shows the influence on the smoothness when the body W is rotated in the horizontal direction and when it is not. A in FIG. 4 shows a state in which the body W is not rotated (conventional coating method). FIG. 4B shows a case where the body W is rotated by 90 ° and then reversed (forward and reverse rotation between FIGS. 2 (a) and (c)). FIG. 4C shows
The case where the body W is rotated by 135 ° and then reversely rotated (forward and reverse rotation between FIGS. 2 (a) and (d)) is shown. 4th
FIG. D shows a case in which the body W is rotated 180 ° and then reversed (forward and reverse rotation between FIGS. 2 (a) and (e)). FIG. 4E shows a case where the body W is continuously rotated in the same direction (FIGS. 2 (a), (b),
(C)... (I) are taken in this order, and the process returns to (a) again).

As is apparent from FIG. 4, if the thickness of the coating film is the same, it is better to rotate the body W (FIG. 4, B, C, D,
E) When the rotation is not performed (FIG. 4A), a greater smoothness can be obtained. In addition, it is understood that even in the same rotation, it is preferable to rotate in the same direction by 360 ° in order to increase the smoothness. Of course, when the body W is not rotated, the thickness of the coating film is limited, and there is a limit in increasing the smoothness.

By the way, the body W is 360
゜ When rotating, the resulting smoothness is
It is "87" (lower limit of 1.0 in PGD value) in IG. When the thickness of the coating film is 40 μm, the IG is “58” (lower limit of 0.7 in the PGD value) when the body W is not rotated. If the IG is "68"
(Lower limit of 0.8 in PGD value).

As is known, IG (image gloss) in the image sharpness indicates the ratio of the sharpness to the mirror surface (black glass) as 100, and the PGD indicates the degree of discrimination of the reflected image as 1.0. Is a value at which the smoothness of the painted surface decreases as the value decreases.

The test conditions of the data shown in FIG. 3 and FIG. 4 are as follows. These test conditions show the conditions when overcoating is performed at P2.

a. Paint: Melamine alkyd (black) Viscosity: 22 seconds / 20 ° C with Ford cup # 4 b. Coating machine: Minibell (16,000 rpm) shaping air
・₂ , 0kg / cm ₂ c. Discharge amount: The first time of spraying divided into two, 100c
c / min 2nd time ··· 150 to 200 cc / min d. Setting time: 10 minutes × normal temperature e. Baking conditions: 140 ° C × 25 minutes f. Base smoothness: 0.6 (PGD value) (intermediate coating, on PE tape) g. Rotating or reversing operation range: Setting (10 minutes) to baking (10 minutes) h. Coating object: Painting on the side of a 30 cm square cylinder, rotatably supported at the center i. Rotation speed of the coating object : 6 rpm, 30 rpm, and 60 rpm were performed, but there was virtually no difference due to the difference in rotation speed. The horizontal axis described here includes a range inclined by about 10 ° with respect to the true horizontal axis.

Spraying of paint in the coating process P2 The body W as an object to be coated is first sprayed with paint on the bonnet, trunk lid, roof panel, etc. as a lateral surface, and then, on a vertical surface such as a fender. Paint is sprayed.

16 and 17, the lateral surface of the body W is indicated by reference numeral 61, and the upright surface is indicated by reference numeral 62. Also, the paint sprayed on the lateral surface 61 is indicated by reference numeral 61A, the paint sprayed on the upright surface 62 is indicated by reference numeral 62A, and the undercoat and intermediate coats are collectively indicated by reference numeral 63 as a base coat. It is. And the sixteenth
The figure shows a state in which the paint is being sprayed on the lateral surface 61, and FIG. 17 shows a state in which the paint is being sprayed on the upright surface 62. As the spraying gun, known electrostatic coating machines (minibell) 64 (for horizontal) and 65 (for vertical) are used.

In FIG. 16, the paint is sprayed on the side surface 61 by reciprocating the coating gun 64 along the side surface 61 at a constant speed. At this time, a masking plate 66 is provided at the boundary between the horizontal surface 61 and the vertical surface 62 so as to protrude from the horizontal surface 61 along the vertical surface 62. Thereby, the side surface 61
Of the paint, most of the paint to be attached to the boundary portion 61a near the elevation 62 (the portion shown as the distance 1 from the surface of the base coating film 63 to the elevation 62) adheres to the masking plate 66. Therefore, the sprayed thickness of the paint on the boundary 61a is
It becomes thinner by a predetermined amount than the other portion 61b of the lateral surface 61 other than the boundary portion 61a. The thickness of the coating of the other portion 61b is equal to or larger than the sag limit.

After the paint is sprayed on the lateral surface 61, the paint is sprayed on the upright surface 62 by reciprocating the coating gun 65 along the upright surface 62 at a constant speed as shown in FIG. When the paint is sprayed on the upright surface 62, the above-mentioned masking plate 66 is removed. Then, a part of the paint discharged from the paint gun 65 is attached to the boundary portion 61a (overspray). Thereby, the thickness of the coating film with respect to the boundary portion 61a, the other portion 61b of the lateral surface 61
And about the same thickness. Of course, the thickness of the coating film with respect to the upright surface 62 is set to be equal to or larger than the sag limit.

As described above, the spray thickness of the paint on the boundary portion 61a is prevented from being extremely large, and as a result, the coating thickness of the boundary portion 61a finally obtained after the drying process P4 is obtained.
It is possible to prevent a situation in which the other portion 61b is extremely excited.

Note that the thickness of the sprayed paint on the boundary portion 61a shown in FIG. 16 is made smaller than the other portion 61b by a predetermined amount in consideration of the degree of concentration of the paint generated when the body W is rotated. It is also possible to put.

Here, after spraying the paint on the upright surface 62 shown in FIG. 17 first, the paint may be sprayed on the lateral surface 61 shown in FIG. And the vertical surface 62 may be simultaneously sprayed with paint. Further, when making the spraying thickness to the boundary portion 61a thinner than the other portion 61b, it is necessary to set the right stroke end position of the coating gun 64 in FIG. 16a far away from the other surface 62 by a considerable distance. In this case, the masking plate 66 may not be provided.

Next, a specific example of a jig used to support the body W so as to be rotatable in the horizontal direction with respect to the carriage D will be described.

FIG. 5 shows a front jig attached to the front of the body W.
Shows 1F. The jig 1F includes a pair of left and right mounting brackets 2, a pair of left and right stays 3 welded to the left and right brackets 2, a connecting bar 4 for connecting the pair of left and right stays 3, and a connecting bar 4. And an integrated rotation shaft 5. In such a jig 1F, the bracket 2 is
It is fixed to a front strength member of the body W, for example, a front end of the front side frame 11. That is, since a bracket 12 for mounting a bumper (not shown) is usually welded to the front side frame 11, the bracket 2 is bolted (not shown) to the bracket 12 on the body W side.
Use to fix.

On the other hand, the rear jig 1R attached to the rear of the body W
Is shown in FIG. The rear jig 1R has the same configuration as the front jig 1F, and the components corresponding to the front jig 1F are denoted by the same reference numerals. This rear jig
To attach the 1R to the body W, the bracket 2 is attached to the floor frame 13 as a strength member at the rear end of the body W.
By fixing with bolts. Of course, at the rear end of the floor frame 13, a bumper mounting bracket is welded in advance because the bumper is generally mounted, so that the rear jig 1R is Mounting can also be performed.

When the jigs 1F and 1R are attached to the body W, the rotating shafts 5 are positioned on the same straight line extending in the front-rear direction of the body W. This same straight line is the rotation axis l of the body W, and is preferably
The rotation axis l passes through the center of gravity G of the body W (see FIG. 7). It should be noted that the rotation axis l passes through the center of gravity G, thereby preventing a large fluctuation in the rotation speed when the body W rotates. This prevents the body W from receiving an impact due to the rotation fluctuation, which is more preferable for preventing dripping.

The front and rear jigs 1F and 1R are for the type of vehicle (the type of body W)
A special one is prepared in advance in accordance with.

Dolly This is a dolly that is used in at least P1, P4, and P5 and has a function of rotating the body W.

In FIG. 7, the trolley D has a base 21, and this base 21
Is mounted on the road surface 23. The base 21 has a single front support extending sequentially upward from the front side to the rear side (from right to left in FIG. 7) in the traveling direction.
24, two intermediate struts 25, 26 and one rear strut 27, and a space between the intermediate struts 25, 26 and the rear strut 27 is a support space 28 with a large space in the front-rear direction. .

The body W is disposed in the support space 28, and the front portion thereof is rotatably supported on the intermediate support 26 using the entire jig 1F, while the rear portion uses the rear jig 1R. And is rotatably supported by the rear support 27.

The front and rear jigs 1F and 1R (the rotating shaft 5) can be freely disengaged from the columns 26 and 27 from above and below, and the rear jig is also provided.
1R is immovably engaged in the direction of the rotation axis l. For this reason, the notch 26a which opens in the upper end surface is formed in the intermediate support | pillar 26 (refer FIG. 10-12), The notch 27a which opens in the upper support surface is formed in the rear support | pillar 27. (First
FIG. 0, FIG. 14, FIG. 15). These two notches 26a, 27a
Is large enough to fit the rotating shafts 5 of the jigs 1F and 1R. The flange 5a is attached to the rotating shaft 5 of the rear jig 1R.
On the other hand, a notch 27b having a shape corresponding to the flange portion 5a communicating with the notch 27a is formed in the rear support column 27. As a result, the rear jig 1R has the notch
It is disengaged from the vertical direction with respect to 27a, 27b, and is immovable in the front-rear direction with respect to the rear support column 27 by the stopper action of the flange portion 5a. The application of the rotational force to the body W is performed via the rotary shaft 5 of the front jig 1F.
(See also FIG. 5).

A stay 29 protrudes downward from the base 21, and a tow wire 30 is connected to a lower end of the stay 29. The wire 30 is of an endless type and is driven in one direction by a motor (not shown), whereby the carriage D is driven in a predetermined transport direction. Of course, the motor is installed at a safe place from the viewpoint of explosion protection.

The rotation of the body W is performed using the movement of the bogie D, that is, using the displacement of the bogie D with respect to the traveling road surface 23. The rotation take-out mechanism 31 for taking out the displacement of the cart D as a rotation is configured as follows. That is, the rotation take-out mechanism 31 includes a rotation shaft 32 extended vertically in the base 21 and supported rotatably, a sprocket 33 fixed to a lower end of the rotation shaft 32, and a chain 34 meshed with the sprocket 33. And is composed of This chain 34
Is arranged in parallel with the wire 30 so as to be immovable with respect to the traveling road surface 23. When the truck D is pulled through the wire 30, the chain 34 is immovable. Sprocket 33 meshing with 34 and therefore a rotating shaft
32 is rotated.

A transmission mechanism 35 for transmitting the rotation of the rotation shaft 32 to (the rotation shaft 5 of) the front jig 1F is configured as follows. That is, the transmission mechanism 35 includes a casing 36 fixed to the rear surface of the front support 24 and a rotating shaft 37 that extends in the lateral direction (front-rear direction) and is rotatably supported by the casing 36.
A pair of bevel gears 38 and 39 for interlocking the rotation shaft 37 and the upper rotation shaft 32, and a connection shaft 40 held rotatably and slidably in the front-rear direction with respect to the intermediate support 25. Have. The connecting shaft 40 is spline-coupled to the rotating shaft 37 (the engaging portion is indicated by reference numeral 41 in FIG. 7). When the rotating shaft 32 is rotated, the connecting shaft 40 is also rotated. become. Of course, the rotation shaft 37 and the connection shaft 40 are installed so as to be located on the rotation axis l.

The connecting shaft 40 is disengaged from the rotating shaft 5 of the front jig 1F. That is, as shown in FIGS. 10 to 12, a cross-shaped connecting portion 5b is formed at the tip of the rotary shaft 5 for the front jig 1F, while the connecting shaft 40 has As shown in FIGS. 10 and 13, a box portion 40a having an engagement recess 40c into which the connecting portion 5b is fitted without play is formed. Thus, for example, the rod 43 is
By sliding the connecting shaft 40 through the connector, the box portion 40a (engaging recess 40c) and the connecting portion 5b are disengaged, and the connecting shaft 40 and the rotating shaft 5 can be integrally rotated during the engagement. It is said. As shown in FIG. 10, the rod 43 is fitted into an annular groove 40b formed on the outer periphery of the box 40a so as not to hinder the rotation of the connecting shaft 40.

With the above configuration, the body W is lowered with respect to the bogie D while the connecting shaft 40 is displaced to the right in FIG. 7, so that the rotating shafts 5 of the front and rear jigs 1F and 1R are It is rotatably supported by the columns 26 and 27 and is immovable in the front-rear direction. Thereafter, the connecting shaft 40 (locking recess 40c) is engaged with (the connection portion 5b of) the rotating shaft 5 in the front jig 1F.
Thus, if the trolley D is pulled through the wire 30, the body W will be rotated about the predetermined horizontal axis l. The removal of the body W from the carriage D may be performed in a procedure reverse to the procedure described above.

(Effects of the Invention) As is apparent from the above description, the present invention provides a coated surface having even more excellent smoothness if the thickness of the coating film is the same, and a boundary portion in the vicinity of the vertical surface in the horizontal surface. Can prevent the swelling of the paint.

[Brief description of the drawings]

FIG. 1 is an overall process diagram showing one embodiment of the present invention. FIG. 2 is a view showing a state of a posture change accompanying rotation of an automobile body as an object to be coated. FIG. 3 and FIG. 4 are graphs showing the relationship among paint thickness, sag, smoothness of the painted surface, and rotation. 5 and 6 are perspective views showing examples of jigs used for rotating the body. FIG. 7 is a side view showing an example of a bogie for body transportation in which the body is rotated. FIG. 8 is a partially cutaway plan view showing a state of the bogie below the traveling path. FIG. 9 is a sectional view taken along line X9-X9 in FIG. FIG. 10 is a side cross-sectional view showing a connecting portion between the rotating jig and the bogie. FIG. 11 is a sectional view taken along the line X11-X11 in FIG. FIG. 12 is a plan view of FIG. FIG. 13 is a sectional view taken along line X13-X13 of FIG. FIG. 14 is a sectional view taken along line X14-X14 of FIG. FIG. 15 is a plan view of FIG. FIG. 16 is a view showing a state where a paint is sprayed on the lateral surface. FIG. 17 is a view showing a state in which paint is sprayed on an elevation. P1 to P4: Process W: Body (object to be coated) l: Rotation axis D: Transport cart 1F, 1R: Rotating jig 61: Side 61a: Boundary 61b: Other parts 61A: Paint (side) 62: Elevated 61B: Paint (elevated) 64: Paint gun (horizontal) 65: Paint gun (elevated) 66: Masking plate

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Takakazu Yamane 3-1, Shinchi, Fuchu-cho, Aki-gun, Hiroshima Prefecture Inside Mazda Co., Ltd.

Claims (1)

(57) [Claims] A coating step of spraying a paint on a lateral surface extending in a lateral direction and a vertical surface extending in a vertical direction of the object to be coated, and a drying step of drying the applied paint. In the coating method, the spraying of the paint on the lateral surface is performed so that a boundary portion of the lateral surface, which is a portion near the vertical surface, is thin and other portions other than the boundary portion have a thickness equal to or greater than the sag limit. The spraying of the paint on the upright surface is performed so as to have a thickness equal to or greater than the sagging limit.In the drying step, the paint applied to the object is cured until sagging does not occur. An object to be coated is rotated about a substantially horizontal axis.