JPS63197578A - Painting method - Google Patents

Abstract

PURPOSE:To form a thick film having high smoothness, by a method wherein dust is removed from an object to be painted in a preparation process while said object is rotated around a horizontal axis and paint is subsequently applied to the object to be painted in a thickness equal to or more than a dripping limit and dried while the object to be painted is rotated around the horizontal axis. CONSTITUTION:The dust removal in a preparation process P1 is performed by air blow while the car body W on a truck D is intermittently rotated around a horizontal axis and, in a paint spraying process P2, paint is sprayed so as to form a paint film far thicker than 40mum becoming a dripping limit. After the alteration of the truck D is rapidly performed, the body W is transferred to a drying process consisting of a setting process P4 and a baking process P5 and the paint is dried while the body W is rotated in the horizontal direction under respective set temp. atmospheres. By rotating the body W in the horizontal direction as mentioned above, no dripping is generated even when the paint film is formed in the thickness equal to or more than the dripping limit and the paint film is smoothly baked and dried.

Description

[Detailed description of the invention] (Industrial application field) The present invention relates to a coating method.

(Prior art and its problems) When painting the outer surface of an object to be painted, such as an automobile body, there are a preparation process for removing dust adhering to the object, a process for applying paint to the object, and a coating process. and a drying step of drying the painted paint. This drying process is generally carried out in two stages: a setting process and a baking process. It is carried out in a temperature atmosphere of @~60@C (baking temperature in the baking process is usually around 140°C).

The object to be coated is usually conveyed by a conveyance means such as a trolley while undergoing the above-mentioned preparation process, painting process, and drying process, but the posture of the object to be coated is subject to change.

Each step is performed while maintaining a predetermined posture.

By the way, one of the criteria for evaluating the quality of painted surfaces is:
It has smoothness (flatness), and the higher the smoothness, the smaller the degree of unevenness on the painted surface, resulting in a better painted surface. It is already known that in order to improve the smoothness of the painted surface, it is sufficient to increase the thickness of the paint film, that is, the film thickness of the applied paint.

On the other hand, something that impedes the quality of the painted surface is "sagging" of the paint. This sagging occurs when the applied paint flows downward under the influence of gravity. The greater the thickness, the more likely ``sagging'' will occur.The cause of this ``sagging'' is ultimately the effect of gravity, so it is more likely to occur on surfaces of the object to be coated that extend in the vertical direction, that is, so-called vertical surfaces.

Therefore, on surfaces extending in the horizontal direction of the object to be coated, that is, so-called lateral surfaces, where "sagging" of the paint does not cause much of a problem, the thickness of the paint applied can be made larger than on the vertical surfaces. In addition, even if the thickness of the paint film on the horizontal surface and the thickness of the paint film on the vertical surface are the same, the unevenness on the horizontal surface will be reduced due to slight flow of the paint that does not cause sagging.
This results in better smoothness than in the vertical plane.

From the above-mentioned point of view, conventionally, in order to prevent the paint from "sagging" and obtain a painted surface with as much smoothness as possible, painting was done using a paint with as little fluidity (low viscosity) as possible. was. The so-called "sag limit" at which paint sag occurs on the vertical surface is a maximum coating film thickness of about 40 pm for conventional paints. More specifically, ``sag'' in the 91 coating tends to occur at the beginning of the setting process and the beginning of the baking process, especially at the beginning of the baking process, and in order to prevent ``sagging'' from occurring during this period, the paint applied during the painting process is The maximum value of the determined thickness, that is, the sagging limit value, is approximately 40 gm. Therefore, if you want to obtain a painted surface with even greater absolute smoothness,
In conventional painting methods, it has been necessary to repeat a series of steps from the painting process to the baking process multiple times, for example, by applying two coats.

The present invention was made in consideration of one or more of the above circumstances, and an object of the present invention is to provide a coating method that allows a coated surface with greater smoothness to be obtained with the same coating thickness. shall be.

(Means and effects for solving the problem) The present invention basically improves the fluidity of the paint by appropriately changing the direction of gravity acting on the paint applied to the object to be coated. By making use of this as a seeding method, it is possible to obtain a coated surface with greater smoothness for the same coating thickness. in particular.

The configuration is as follows. That is, there is a preparation process in which dust adhering to the workpiece is removed while the workpiece is rotated around a horizontal axis, and paint is applied to the workpiece from which the dust has been removed to a thickness that exceeds the sag limit. With the painting process.

The drying process includes rotating the object to be coated around a horizontal axis while drying the paint applied to the object.

In this way, in the present invention, the direction of gravity acting on the paint applied to the object to be coated is changed by rotating the object in the horizontal direction, so that the paint does not sag. It will be dried without drying.

According to the present invention, the film thickness of the paint applied per coat can be made much thicker than before, and an extremely good painted surface with smoothness that far exceeds the level conventionally considered to be the limit can be obtained. can.

Further, even when the thickness of the coating film is the same as that of the conventional coating, the fluidity of the coating material can be utilized to obtain an excellent coated surface with smaller irregularities, that is, greater smoothness.

゛ Furthermore, in order to obtain a painted surface with the same level of smoothness as, for example, the same level of smoothness obtained with conventional painting methods, the film thickness of the paint to be applied can be made thinner than with conventional painting methods. , the amount of paint used can be reduced by the amount that can be made thinner.

Of course, thin p! Paints that cause "sag" even with iS can be obtained by reducing the components that inhibit fluidity from conventional paints by a predetermined percentage (conventional paints contain fluidity additives to improve the sag limit). A hybrid agent is mixed in to reduce the

In addition, since dust is removed while rotating the object to be coated around the horizontal axis in the preparation process, dust will not fall from the object when rotating around the horizontal axis in the drying process. It is possible to reliably avoid a situation where the paint sticks to the painted surface. By the way, if you only remove dust without rotating the object to be coated in the preparation process, it is virtually impossible to completely remove the dust that falls when the object is rotated or rotated. It becomes difficult.

As described above, according to the present invention, it is possible to obtain a high-quality painted surface that not only has good smoothness but also is free from dust.

(Example) Hereinafter, an example of the present invention will be described based on the attached drawings.

L Raw Goho I Figure 1 shows the overall process for painting an automobile body W as an object to be coated, and each process is indicated by P1 to P5.

First, the body W, which has been undercoated by electrodeposition coating in a known manner, is sent to the preparation step Pi while being held on a trolley. In this preparatory step P1, dust inside and outside the body W is removed by, for example, air blowing or vacuum suction. After that, in step P2, paint is sprayed onto the body W. After the carriage is changed in step P3, the paint is dried in setting step P4 and baking step P5.

If the steps P1 to P6 are for intermediate coating, the body W is sent to the top coating step after step P5. Also, process P
If 1 to P6 are for topcoating, the body W is transported to an assembly line in a known manner.

Dust removal in the removal process Pi is performed while rotating the body W around the horizontal axis, as shown in FIG. That is, for example, first, the rotation of the body W is stopped in the state shown in FIG. 2(a) to remove dust, and then the dust is removed as shown in FIG. 2(b).
The posture of the body W is changed to the state shown in FIG. In this way, dust is removed while the body W is intermittently rotated as shown in (c), (d), . . . (f) in FIG.

In this way, by removing dust while rotating the body W, it is possible to remove dust adhering to closed sections such as the inside corners of the roof panel and side sills of the body W, i.e., if the body W is not rotated. It becomes possible to completely remove even the garbage that does not fall.

The rotation range of the body W is 36 degrees as shown in FIG.
It may be rotated by 0°, but it may be rotated by an appropriate angle, such as by rotating within a range of 180° (the range shown in Fig. 2 (a) and (e)), in accordance with the rotation of the body W in the drying process that will be explained later. can be taken as a thing.

To describe the preferred method of removing trash in more detail: 1
The order is as follows.

■Stop the body W in the state shown in Fig. 2(C).

In this state, air blows (flow) the underfloor part of the body W and the inside of the engine room.5. Oky/cm
2 - Same hereafter).

■Stop the body W in the state shown in FIG. 2(d).

In this state, the inside of the body W and the inside of the door are blown with air.

■ Stop the body W in the state shown in t52 (Ce).

In this state, air blow the inside of the trunk room.

■Stop the body W in the state shown in FIG. 2(f).

In this state, air blow to the same area as in (2) above.

■Stop the body W in the state shown in Fig. 2(g).

In this state, air blow to the same area as in (2) above.

■Stop the body W in the state shown in Fig. 2 (X) (Fig. 2 (a)). In this state, air blow is applied to all the outer panels of the body W, and the outer panels of the hind limb body are wiped with a sponge.

Start painting.

First, the paint is sprayed in P2 so that the thickness of the paint film exceeds the sag limit. In other words, with the paints commonly used in the past, the maximum thickness of the paint that does not cause sag, that is, the sag limit value, is about 40 pm.
In step P2, the paint is sprayed to form a coating film much thicker than the sag limit of 40 gm (for example, 65 ILm).

After this P2, the carriage is quickly changed in P3, and then the process moves to the setting step of P4. In this setting step P4, 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 around a rotation axis extending in the horizontal direction, and in the embodiment, this rotation axis extends in the front-rear direction of the body W. The temperature atmosphere in this setting step P4 is set to room temperature in the example, but it may be set to an appropriate temperature in a lower temperature range than the temperature atmosphere in the next baking step P5, such as 40'' to 60°C. Of course, this setting step P4 is to volatilize the low boiling point content in the paint in advance, so that -
In the next baking step P5, pinholes are prevented from occurring on the painted surface due to rapid volatilization of low boiling point components.

In the baking step P5, the paint is baked in an atmosphere at a temperature of, for example, 140°C. Even in this P5, P
Same as setting step 4.

As shown in FIGS. 2(a) to 2(i), the body W is rotated in the horizontal direction.

P4 mentioned above. Due to the horizontal rotation of the body W at P5, even if the paint is sprayed to a thickness exceeding the sag limit at P2, the paint dries without sagging. As a result, a high-quality coated surface with extremely high smoothness that could not be obtained with conventional coating methods can be obtained.

The reason why the cart is changed in P3 is to prevent paint from adhering to the cart used in the drying process in P4 and P5. In other words, in P2, a considerable amount of paint is sprayed onto the truck, but if the truck with this paint adhered is used as is and transferred to the drying process, the paint adhered to the truck will be sprayed onto the truck. This is because as the trolley moves, a considerable amount of paint may peel off and become dust, which may impair the quality of the painted surface.

,・Relationship between film thickness, sag limit, smoothness, and flat rotation Part 3
The figure shows the influence of coating film thickness on the sag limit. In this Figure 3, the coating film thickness is 40 lm.
, 53 m% and 65 m% are shown.

It is understood that for any of these thicknesses, peaks of sag occur both at the beginning of the setting process and at the beginning of the baking process. This value refers to the value at which sag occurs (the painted surface is considered to be defective if sag of 2 mm/min or more occurs when visually observed), and the maximum coating thickness that can be obtained within the range below this sag limit is the same as the conventional The amount of paint is approximately 401Lm.

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 rotated. In Fig. 4, A shows the state in which the body W is not rotated (conventional painting method), and Fig. 4 B shows the state in which the body W is not rotated.
The figure shows the case where it is rotated by 9.0 degrees and then reversed (
Figure 2 (L) and (C) are rotated forward and backward), Figure 4 C shows the case where the body W is rotated 135 @ and then reversed (Figure 2 (a) and ( d)),
The fourth diagram shows the case where the body W is rotated by 180 degrees and then reversed (forward and reverse rotation between Figure 2 (a) and (e)), and Figure 4 E shows the case where the body W is rotated 180 degrees and then reversed. This shows the case of continuous rotation in the same direction (Fig. f82 (a), (b)
, (C)...takes the posture in the order of (i) and returns to (a) again).

As is clear from Fig. 4, if the thickness of the coating is the same, it is better to rotate the body W (Fig. 4 B, C, D, E).
), thicker smoothness can be obtained than in the case of no rotation (FIG. 4A). Furthermore, it is understood that even if the rotation is the same, it is preferable to rotate 360 degrees in the same direction in order to improve the smoothness. Of course, if the body W does not rotate,
Since there is a limit to the thickness of the coating film, there is a limit to how much smoothness can be increased.

By the way, assuming the thickness of the paint film is 65pm, the body width is 36mm.
When rotated by 0°, the obtained smoothness is 1. r87J in G (lower limit of 1.0 in PGD value)
And, when the thickness of the coating film is 40 gm,
If the body W does not rotate, 1. r58J in G (P
The lower limit of GD value is 0.7), whereas when the body W is rotated 360@, it is 1. G de re8J CPG
The lower limit of D value is 0.8).

As is well known, IG (image gloss) in terms of image sharpness indicates the ratio of sharpness to a specular surface (black glass) of 100, and PGD indicates the degree of discrimination of a reflected image to 1. This is a value at which the smoothness of the painted surface decreases as it decreases from 0.

The test conditions for the data shown in FIGS. 3 and 4 are as follows, and these test conditions indicate 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, OOOrpm) Shaping air 0.2, 0 kg 7 cm2 C0 discharge amount: divided into 2 times The first spraying...
100cc/+nfn 2nd time, 150-200cc/min, Setting time: 10 minutes x room temperature e, Baking conditions: 140" CX25 molecules, Base smoothness: 0.6 (PGD value) (Intermediate coating, PE (on tape) g0 Rotation or reversal operating range: Setting (10 minutes) to baking (10 minutes) h, Painted on the side of a rectangular cylinder with a knee side of 30 cm, Supported rotatably in the center i, Worked object Rotation speed: 6 rpm, 30 rpm.

The rotation was carried out at three different rotational speeds of 60 rpm, and in fact no difference occurred due to the difference in rotational speed.

(Hereinafter, blank space) Rotating jig Next, a specific example of a jig used for rotatably supporting the body W in the horizontal direction with respect to the trolley section will be described.

Figure 5 shows the front jig I attached to the front of the body W.
This jig IF, indicated by F, 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, and a connecting bar 4 that connects the pair of left and right stays 3P. , and a rotating shaft 5 integrated with the connecting bar 4. The bracket 2 portion of such a jig IF is fixed to the front strength member of the body W, for example, to the front end of the front side frame 11. That is, since a bracket 12 for normally mounting a bumper (not shown) is welded to the front side frame 11, this body W
The bracket 2 is fixed to the side bracket 12 using a bolt (not shown).

On the other hand, the rear jig IR attached to the rear part of the body W is shown in FIG. The rear jig IR has a similar configuration to the front jig IF, and the same reference numerals are given to the components corresponding to the front jig IF. The rear jig IR is attached to the body W by fixing the bracket 2 to the floor frame 13 as a strength member at the rear end of the body W with bolts. Of course, at the rear end of the floor frame 13,
Since the bumper mounting bracket is generally welded for mounting the bumper, the rear jig IR can also be mounted using this bumper mounting bracket.

When the front and rear jigs IF and IR are attached to the body W, their rotating shafts 5 are positioned on the same straight line extending in the front-rear direction of the body W. This same straight line serves as the edge of the rotation axis of the body W, and preferably, this edge of the rotation axis is the center of gravity G of the body W (see Fig. 7).
It is made to pass through. Note that since the rotation axes intersect through the center of gravity G, large fluctuations in rotational speed are prevented when the body W rotates. This prevents impact from occurring on the body W due to rotational fluctuations, which is more preferable in terms of preventing sagging.

Note that the front and rear #h tools IF and 1R are specially prepared in advance according to the vehicle type (type of body W).

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

In FIG. 7, the trolley has a base 21, and this base 2
Wheels 22 attached to the vehicle 1 are run on a road surface 23. This base 21 consists of one front support 24, two wooden intermediate supports 25, 26, which extend upward in sequence from the front side in the running direction to the rear side (from the right side to the left side in FIG. 7), respectively. and one support space 28 having one rear strut 27, with a large distance between the intermediate strut 25, 26 and the rear strut 27 in the front-rear direction.
It is said that

The body W is disposed in the support space 28, and its front part is rotatably supported with respect to the intermediate support 26 using the front jig IF, while its rear part is supported using the rear jig IR. It is rotatably supported by the rear support 27.

The front and rear jigs IF and IR (rotary shafts 5 of them) can be freely engaged with and disengaged from the columns 26 and 27 from the vertical direction, and the rear jig IR is immovably engaged in the vertical direction of the rotation axis. Ru.

For this reason, a notch 28a that opens on the upper end surface of the intermediate support 26 is formed (see FIGS. 1θ to 12).
, a notch 27a that opens on the upper end surface of the rear support 27 is formed (see Fig. 1θ, Fig. 14, and Fig. 15).
, these notches 26a, 27a are for the treatment IJctF, IR
The size is such that the rotating shaft 5 of the rotary shaft 5 can fit therein. and,
A flange portion 5a is formed on the rotating shaft 5 of the rear jig IR, while a notch 27b having a shape corresponding to the flange portion 5a communicating with the notch 27a is formed in the rear support 27. As a result, the rear jig IR is engaged with and disengaged from the notches 27a and 27b of the rear column 27 from above and below, and the rear column 2
7, it is immobile in the front and back direction. Note that the rotational force is applied to the body W via the rotation shaft 5 of the front jig IF, and therefore, the tip of the rotation shaft 5 of the front jig IF has a
A connecting portion 5b (see also FIG. 5), which will be described later, is formed.

A stay 29 is provided to protrude downward from the base 21,
A traction wire 30 is connected to the lower end of this stay 29. This wire 30 is of an endless type,
It is driven in one direction by a motor (not shown), and thereby the trolley is driven in a predetermined transport direction. Of course, the motor is installed in a safe location from an explosion-proof point of view.

The rotation of the body W is performed by using the movement of the truck, that is, by using the displacement of the truck with respect to the running road surface 23. A rotation extraction mechanism 31 for extracting the displacement of the truck as rotation is configured as follows. In other words, the one-rotation take-out mechanism 31 includes a rotating shaft 32 extended vertically and rotatably supported on a base 21, a sprocket 33 fixed to the lower end of the rotating shaft 32, and a sprocket 33 fixed to the lower end of the rotating shaft 32.
The chain 34 is meshed with the chain 34. This chain 34 is disposed in parallel with the wire 30 in an immovable state with respect to the running road surface 23. This results in
When the trolley is pulled through the wire 30, the chain 3
Since the chain 4 is stationary, the sprocket 33 meshing with the chain 34 rotates the rotating shaft 32 accordingly.

The rotation of the rotation shaft 32 is controlled by the rotation shaft 5 of the front jig IF.
The transmission mechanism 35 for transmitting the signal is configured in a first-order manner. That is, the transmission mechanism 35
The casing 36 fixed to the rear surface of 4 and the casing 3
6, a rotating shaft 37 extending laterally (back and forth) and rotatably supported, a pair of bevel gears 38 and 39 that interlock this rotating shaft 37 and the upper rotating shaft 32, and The connecting shaft 40 is held rotatably and slidably in the front-rear direction. This connecting shaft 40 is 1
It is spline-coupled to the rotating shaft 37 (this engaging portion is indicated by reference numeral 41 in FIG. 7), so that when the rotating shaft 32 is rotated, the connection @40 is also rotated. Of course, the one-rotation shaft 37 and the connection shaft 40 are installed so as to be located on the axis of rotation.

The connecting shaft 40 is connected to the rotating shaft 5 of the front jig IF.
be disengaged. That is, as shown in FIGS. 10 to 12, a cross-shaped connecting portion 5b is formed at the tip of the front jig IF rotating shaft 5, while a cross-shaped connecting portion 5b is formed at the end of the connecting shaft 40. 1
As shown in FIG. 0 and FIG. 13, a box portion 40 has an engaging recess 40c into which the connecting portion 5b is fitted without rattling.
a is formed. Therefore, for example, by sliding the connecting shaft 40 via the rod 43 by a pneumatic cylinder 42, the box portion 40a (engaging recess 40c) and the connecting portion 5b are engaged and disengaged, and when they are engaged, they are connected. The shaft 40 and the rotating shaft 5 are allowed to rotate together. In addition,
The rod 43 is connected to a connecting shaft 40 as shown in FIG.
The box part 40a is fitted into an annular groove 4Ob formed on the outer periphery of the box part 40a so as not to inhibit the rotation of the box part 40a.

With the above configuration, by lowering the body W relative to the trolley while the connecting shaft 40 is displaced to the right side in FIG. 7, the rotating shafts 5 of the front and rear jigs IF and IR
It is rotatably supported by intermediate struts 26 and 27 in an immovable state in the front-rear direction. After this, the connecting shaft 40 (locking recess 4
0c) is the connection part 5b of the rotating shaft 5 in the pretreatment AIF.
) is engaged with. Thereby, when the trolley is towed via the wire 30, the body W is rotated around a predetermined horizontal shaft rim. In addition, the removal of the body W from the trolley may be performed in the reverse order to the above-described procedure.

FIGS. 16, 17, 18, and 19 each show a modification of the connecting portion between the rotating shaft 5 of the front jig IF and the connecting shaft 40. FIG.

16 and 17, first, the notch @26a of the intermediate support 26 is formed in a semicircular shape so as to be able to rotatably support the box portion 40a. Furthermore, while the connecting portion 5b-1 of the rotating shaft 5 is formed in an L-shape, the L-shaped connecting portion 5b-1 is engaged with the engaging recess 40cm1 formed in the box portion 40a in a manner that prevents relative rotation. It has a shape and size. The engagement recess 40cm1 has an opening C in one side of the box part 40a, and when this opening R3 faces upward, the connection part 5b-1 is inserted into the engagement recess 40cm.
cm1 from above and below (sliding of the connecting shaft 40 is not required).

18 and 19, the rotation axis of the front jig IF is shown only when the engagement recess 40 cm2 formed in the box part 40a faces the E direction, as in FIGS. 17 and 18. 5
The connecting portion 5b-2 formed in the shape can be connected and disconnected, and the connecting portion 5cm2 has a rectangular cross section,
The difference from the cases shown in FIGS. 16 and 17 is that the engaging recess 40 cm2 has a shape corresponding to this square.

Of course, in the cases shown in FIGS. 16 to 19, the storage shaft 4
0 and the front jig IF can be engaged and detached (engagement recess 40c
In the case 8) where m1.40cm2 faces upward, the body W
is in the upright position (the roof panel of the body W is facing upward as shown in FIG. 7).

This is a device for changing the carriage at P3 at 11LIξ, and examples thereof are shown in FIGS. 20 to 22.

As shown in FIG. 22, this cart changing device is installed at a transfer station S1 where a cart movement trajectory R1 in the previous process and a cart movement trajectory R2 in the post process are close to each other. The trolley changing device installed at this transfer station Sl is the 20th
As shown in FIG.

This lifter 51 includes a pair of left and right guide posts 52, a base 53 attached to each guide post 52 so as to be vertically driven, and each base 53.

Support legs 54 are each driven to extend and contract. Each of these support legs 54 is

A pair of front and rear support parts 54a spaced apart in the moving direction of the trolley
has.

In the above configuration, the trolley supporting the body W from the previous process is stopped at the transfer station Sl6.
When the trolley is stopped, the support legs 54 are extended from the base 53 located at the bottom.

The base 53 is moved upward. As a result, Fig. 20,
As shown in FIG. 1, the body W on the trolley has support legs 54
While the side sill or floor frame portion of the body W is supported by the supporting portion 54a, it is lifted from the trolley and raised to a high position. Thereafter, the cart for the previous process leaves the transfer station S1, and the cart for the post process is newly located at the transfer station S1. After this, the base 53 is lowered and the body W is transferred to the trolley. Then, in preparation for the next transfer, the support legs 54 are retracted (see the dashed line in Fig. 21), and in this way, the body W is transferred from the front-process cart to the post-process cart. be done.

Of course, when transferring the body W, it is preferable to firmly fix the dolly in a predetermined position in an immovable state using a positioning device or the like that clamps the dolly from the front, back, left and right directions.

The transfer device for the trolley is assumed to have a hanger that is intermittently fed to a high place, and after the body W is transferred to the hanger by the lifter 51, this hanger moves the body W above the trolley for post-processing. The body may be moved, and at this position, the lifter may be used again to transfer the body from the hanger to a cart for post-processing.

(The following is a blank space) Yuki yo J Now, next, supplementary explanation related to the present invention and the trolley,
Modifications of the painting method, etc. will be explained in sequence.

■When applying the top coat after the intermediate coat, the wet sanding after the intermediate coat baking process can be eliminated. In this case, the body W may be rotated only during either the intermediate coating process or the top coating process, that is, 1f!
The quality of the final painted surface obtained after 1i painting is determined by the quality of the intermediate coating, but when the body W is rotated during the intermediate coating, the finish level of this intermediate coating should be increased. This eliminates the need for conventional water grinding. Also, if you rotate the body W with top coating,
Even without wet sanding with the intermediate coat, the poor finish of the intermediate coat can be compensated for by the quality of the coat.

■When rotating the body W with the top coat and forming a thin coating film with a top coat with a small sag limit, it is recommended to use a so-called color intermediate coat, which allows the intermediate coat to show through the top coat. Even if you can see it, it will be completely unreliable in terms of color.

■Rotation of body W regardless of whether the trolley is running or stopping.

The switching to stop and the switching to change in the rotational direction can be accomplished by using a separate dedicated 7-cut unit such as an air motor, for example, but they can also be accomplished, for example, in the following manner. First, in the example shown in FIG. 7, the first and second wheels mesh with the sprocket 33 from opposite sides in the radial direction. If a second pair of chains (corresponding to the chain 34) is provided and each chain is configured so that it can be driven as appropriate, then depending on the following drive mode, The rotation of the body W will be controlled.

■ Stopping the first chain and freeing the second chain: In this case, the body W is rotated in one direction as the trolley moves.

■First chain free and second chain stopped: In this case, the body W is rotated in the opposite direction to the above (■) as the trolley moves.

■Both chains are free m: In this case, the body W is not rotated as one car moves.

(1) Driving the first chain in one direction and freeing the second chain: In this case, even if one bogie is stopped, the body W is rotated in one direction.

■ Driving the first chain in the other direction and freeing the second chain (same even if the ffil chain is free and the second chain is driven in the other direction): In this case, even if the bogie is stopped, the body W is rotated in the opposite direction to the case of @ above.

Note that the above description also applies when a rack bar is used instead of the chain. If this rack bar is always placed in a fixed state (in this case, the running of the trolley is
By arranging the rack bar intermittently or arbitrarily setting the position of the rack bar to the left or right, the body W can be moved in any direction according to the traveling position of the bogie. The body W can be rotated and the rotation of the body W can be stopped at an arbitrary position.

(2) It is also possible to rotate the body W only during the baking process of the drying process.

(Effects of the Invention) As is clear from the above description, the present invention utilizes the application of paint with a thickness exceeding the sag limit and the rotation of the object to be coated to achieve a coating thickness that is higher than that of conventional paints for the same paint thickness. It is also possible to obtain a high-quality painted surface with high smoothness.

In addition, since dust is removed while rotating the object to be coated during the preparation process, there is no chance of dust falling even when the object is rotated in the subsequent drying process, and no dust is attached. A good painted surface can be obtained.

[Brief explanation of the drawing]

FIG. 1 is an overall process diagram showing one embodiment of the present invention. FIG. 2 is a diagram showing a state in which the posture of an automobile body as an object to be coated changes as it rotates. Figures 3 and 4 are graphs showing the relationship between paint thickness, blurring, smoothness of the painted surface, and rotation. FIGS. 5 and 6 are perspective views showing examples of jigs used to rotate the body. FIG. 7 is a side view showing an example of a body transport trolley in which the body can be rotated. FIG. 8 is a partially cutaway plan view showing the state below the running path of the bogie. FIG. 9 is a sectional view taken along the line X9-X9 in FIG. FIG. 10 is a side cross-sectional view showing the joint portion between the rotating jig and the truck. FIG. 11 is a sectional view taken along the line X1l-Xll in FIG. 10. FIG. 12 is a plan view of FIG. 11. FIG. 13 is a sectional view taken along the line X13-X13 in FIG. 10+7). FIG. 14 is a sectional view taken along the line XL4-XIA in FIG. 10 (7). FIG. 15 is a plan view of FIG. 14. Figures 16 and 17 show modified examples of the joint portion between the rotating jig and the trolley.
6-X16 line sectional view. FIG. 17 is a side sectional view. Fig. 18 and Fig. 19 show still another modification of the joint portion between the rotating jig and the cart, and Fig. 18 is similar to Fig. 19 (Fig. 19).
7) A sectional view taken along the line X18-X18, and FIG. 19 is a side sectional view. FIG. 20 is a side view showing an example of a device for changing the truck. FIG. 21 is a front view of FIG. 20. FIG. 22 is a simplified plan view showing an example of the traveling route of the bogie and the arrangement position of the bogie changing device. Pi-P5: Process W: Body i: Rotation axis D: Transport trolley 1F, IR: Rotation jig

Claims (1)

[Claims] (1) Preparation step of removing dust attached to the workpiece while rotating the workpiece around the horizontal axis, and applying paint to a thickness exceeding the sag limit on the workpiece from which the dust has been removed. and a drying step of drying the paint applied to the object while rotating the object around a horizontal axis.