JPS63197579A - Painting method - Google Patents

Abstract

PURPOSE:To certainly prevent the dripping of paint, by rotating an object to be painted which is coated with the paint in a painting process so as to obtain a thickness equal to or more than a dripping limit, in both of a setting process and a baking process. CONSTITUTION:In a top coating process P10, paint is sprayed so as to form a paint film far thicker than 40mum becoming a dripping limit, for example, so as to obtain a thickness of 65mum. After thee alteration of a truck D is rapidly performed, a car body W is transferred to a setting process P12 and the low b.p. component in the paint is volatilized under a temp. atmosphere of about 40-60 deg.C while the body W is rotated around the rotary axis in the horizontal direction. In a succeeding baking process P13, the paint is baked, for example, under a temp. atmosphere of about 140 deg.C while the body W is rotated in the horizontal direction. As a result, the paint is dried without generating dripping and a high quality painting surface having high smoothness is obtained.

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 step of applying a paint to the object and a drying step of drying the applied paint. This drying process is generally carried out in two stages: a setting process and a baking process. ” to be carried out in a temperature atmosphere of ~60°C (
The baking temperature in the baking process is usually around 140℃).

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 paint sagging.This sagging occurs when the applied paint flows downward when subjected to a single gravitational force. The larger the thickness, the more likely it is that sagging will occur.The cause of this sag is ultimately the effect of gravity, so it is more likely to occur on surfaces that extend in the vertical direction of the object to be coated, 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 is less 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.
A smoothness better than that in the vertical plane can be obtained.

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 gm for conventional paints. More specifically, paint sag is particularly likely to occur both at the beginning of the setting process and at the beginning of the baking process;
The thickness of the paint to be applied in the painting process is determined so as not to occur, and the maximum value of this determined thickness, that is, the sagging limit value, is approximately 40 gm. Therefore, in order to obtain a painted surface with even greater absolute smoothness, with conventional painting methods, it is necessary to repeat the series of steps from the painting process to the baking process multiple times, for example by applying two coats. was there.

The present invention has been made in consideration of the above-mentioned circumstances, and an object of the present invention is to provide a coating method that can obtain a coated surface with even greater smoothness if the coating thickness is the same. purpose.

(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 actively taking advantage of this, you can obtain a coated surface with greater smoothness for the same coating thickness. Specifically, the configuration is as follows. Namely.

A painting process in which paint is applied to the object to be painted, a baking process in which the applied paint is dried by baking, and a set in which the paint is dried at a lower temperature than the baking process between the painting process and the baking process. In a painting method that includes a coating process.

In the painting step, the paint is applied to a thickness exceeding the sag limit, and in the setting and baking steps, the object to be coated is rotated horizontally.

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. In particular, since the object to be coated is rotated during both the baking process and the setting process, which tend to cause paint to sag, it is possible to reliably prevent paint from sagging.

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, if you try to obtain a painted surface with the same smoothness, for example, the same level of smoothness as that obtained with conventional painting methods,
The film thickness of the paint to be applied can be made thinner than in the conventional method, and the amount of paint used can be reduced by the amount that can be made thinner.

Of course, paints that cause "sagging" even in thin coatings can be obtained by reducing the components that inhibit fluidity in conventional paints by a predetermined percentage. (A hybrid agent is mixed in to reduce fluidity.)

As described above, in the present invention, if the same amount of paint is used (the same thickness of one coat), a coated surface with greater smoothness than before can be obtained.

In particular, the thickness of each coat that needs to be applied per coat can be made far greater than what was previously thought to be the limit, resulting in an extremely smooth coating that cannot be obtained with conventional coating methods. It is possible to obtain a high-quality painted surface with a high degree of strength.

(Example) An example of the present invention will be described below based on the attached drawings.

Figure 1 shows the overall process for painting an automobile body W as an object to be coated, and each process is designated by P1 to P13.

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, vacuum suction.

Thereafter, the bogie is changed in step P2, and then an intermediate coating is sprayed onto the body W in step P3. In step 4, after the carriage is changed again, the intermediate coating is dried in a setting step P5 and a baking step P6.

After the baking process P6 for intermediate coating, the carriage is changed in process P7, and then processes P8 to P13 for top coating are performed. The steps P8 to P13 for the top coat correspond to the steps P1 to P6 for the intermediate coat, and are substantially different from Pi-P6 except that the paint used in PIO is used for hazing. However, since there is no such thing, the redundant explanation will be omitted.

Then, after step P13, that is, the body W on which the top coating has been completed is transported to an assembly line as is known.

・Spraying of paint and drying is performed in P3 (intermediate coating) and PLO (top coating), and drying is performed in P5, P6 (intermediate coating) and Pi2, Pi3 (top coating), but from P3 to P
6 and PIO to P13 are substantially the same except for the difference between intermediate coating and top coating, so the description will focus on PIO to P13.

First, the paint (for top coating) is sprayed in the PIO so that the thickness of the paint film exceeds the sag limit. In other words, with conventionally commonly used paints, the maximum thickness of paint that does not cause "sag", that is, the sag limit value, is 406 m.
However, in process PIO, this sagging limit is 4
The paint is sprayed to give a coating much thicker than 01Lm (eg 65ILm).

After this PlO, the carriage is quickly changed in Fil, and then the process moves to the setting process of Pi2.

In this setting step P12, as shown in FIGS.
As shown in , the body W is rotated in the horizontal direction. That is, the body W is rotated around a rotating shaft extending in the water direction f, and in the embodiment, this rotating shaft edge stand extends in the front-rear direction of the body W. In addition, the temperature atmosphere in this setting step P12 is room temperature in the example, but it may be 40° to 60"C, etc. in the next baking step P.
An appropriate temperature can be set within a temperature range lower than the temperature atmosphere at step 13. Of course, this setting step P12 is
This is to volatilize the low boiling point content in the paint in advance.
This prevents the occurrence of pinholes on the painted surface due to the rapid volatilization of low boiling point components in the next baking process P13.
be done.

In the baking step P13, the paint is baked in an atmosphere at a temperature of 1406C, for example.

This Pi3 also has the same setting process as the Pi2.
As shown in FIGS. 2(a) to 2(i), the body W is rotated in the water direction 1z.

Due to the horizontal rotation of the body W in Pi2 and Pi3 described above, even if the paint is sprayed to a thickness exceeding the sag limit due to pH, 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.

Note that changing the trolley at P4 and pH is performed at P5.
This is to prevent paint from adhering to the trolleys used in the drying process in P6, Pi2, and Pi3.In other words, in P3 and PIO, a considerable amount of paint will be sprayed onto the trolleys. If a dolly with paint adhered to it is used as is and transferred to the drying process, a considerable amount of the paint adhering to this dolly will peel off as the abutting dolly moves and become dust, impairing the quality of the painted surface. This is because there is a possibility that The purpose of changing the carts of P2, P7, and P9 was to minimize the influence of dust on the painted surface, but P4. The necessity is small compared to changing the truck in Fil.

The f53 diagram for paint) and sag (field and mo) and -○ rotation shows the influence of coating film thickness on the sag limit. In this Figure 3, the coating film thickness is 40ILm,
Three cases are shown: 534m and 65ILm. 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. Also, the sagging limit is usually 1 minute per minute.
This is the value when sagging of ~2mm occurs (visually 2mm).
The coated surface is considered to be defective if it sag for 7 minutes or more), and the maximum coating thickness that can be obtained within the range below this sag limit is about 40 lm with conventional paints.

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.
Figure 4C shows the case of rotating 90° and then reversing it (forward and reverse rotation between Figure 2 (a) and (C)).
The figure shows the case where the body W is rotated 1351 degrees and then reversed (forward and reverse rotation between Figure 2 (a) and (d)), and the fourth diagram shows the case where the body W is rotated 180 degrees and then reversed. Fig. 4E shows the case where the body W is rotated continuously in the same direction (forward and reverse rotation between Fig. 2 (a) and (e)). Figure 2 (a), (b), (
c)... Take the posture in the order of (i) and return 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° 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 657 cm, the body W is 3.
When rotated by 60 degrees, the obtained smoothness is equal to the image sharpness of 1. G is rs7J (lower limit of 1.0 in PGD value), and if the thickness of the coating is 40gm, if the body W does not rotate, it is 1. r58J in G
(The lower limit of PGD value is 0.7), whereas when the body W is rotated 360@, it is 1. r68J in G (
The lower limit of PGD value is 0.8).

As is known, IC (image gloss) in mapping sharpness indicates the ratio of sharpness to a mirror surface (ring glass) of 10O, 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 Fig. 3 and fiS4 are as follows.

The test conditions are as follows: PIO1P12,
The conditions for overcoating with PI3 are shown below, and P5, P
Horizontal rotation was not performed during intermediate coating in step 6 (
Intermediate coating is the traditional painting method).

a, Paint: Melamine alkyd (black) Viscosity: 22 seconds/20”C with Ford cup #4 b, Coating machine: Minibell (16, OOOrpm) Shaping air 1.2.0 kg 7 cm2 C1 discharge amount = divided into 2 times The first spraying...
100cc/min 2nd time, 150-200cc/min, Setting surface distance: 10 minutes x room temperature e, Baking conditions: 140' CX25 molecules, Base smoothness: 0.6 (PGD value) (Intermediate coating, (on PE 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, rotatably supported in the center i, coated Object rotation speed: 6rpm, 30rpm, 60r
The test was carried out at three different rotational speeds, but in fact no difference occurred due to the difference in rotational speed (see the margin below). A specific example of the jig used for this will be explained.

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 each of the left and right brackets 2, and a connecting bar 4 that connects the left and right pair of stays 3. , 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 the front side frame 11 is usually welded with a bracket 12 for attaching panties (section shown), the bracket 2 is attached to the bracket 12 on the body W side by attaching the bolt (section shown). Use and fix.

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 the same structure as 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 a port. Of course, at the rear end of the floor frame 13,
Since several bumper mounting brackets are generally welded together due to the way the bumper is mounted, the rear jig IR can also be mounted using the bumper mounting bracket I.

When the first and second 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. In addition, since the rotating shaft rim passes through the center of gravity G, large fluctuations in the 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 sag.

Note that the two jigs IF and IR are specially prepared in advance according to the vehicle type (type of body W).

The trolley is used at least in P5, P6, PI3, and PI3 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 has one front support 24, two intermediate supports 25, 26, and one rear support that 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). It has a support column 27, and a support space 28 is provided between the intermediate column 25, 26 and the rear column 27 with a large gap in the front-rear direction.

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 support columns 26 and 27 from the vertical direction, and the rear jig IR is engaged with the rotation shafts MU immovably in the force direction. Ru.

For this reason, the intermediate support 26 is formed with a notch 26a that opens at its upper end surface (see FIGS. io to 1512), while the rear support 27 has a notch 327 that opens at its one end
a is formed (@io figure, ff114 figure, 15th
(see figure), these notches 26a, 27a are the jig IF,
The size is such that the rotating shaft 5 of the IR can fit therein. A flange portion 5a is formed on the rotating shaft 5 of the rear jig IR, and a notch 27b having a shape corresponding to the flange i5a communicating with the notch 27a is formed in the rear support 27. As a result, the rear jig IR is engaged and disengaged from the vertical direction with respect to the notches 27, a, 27b of the rear column 27, and is immovable in the front and rear direction with respect to the rear column 27 due to the stopper action of the flange portion 5a. It is said that Note that the rotational force is applied to the body W on the front side! This is carried out via the rotating shaft 5 of the fi tool IF, and for this reason, a connecting portion 5b (see also FIG. 5), which will be described later, is formed at the tip of the rotating shaft 5 of the front jig IF.

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. That is, the rotation take-out mechanism 31 includes a rotation shaft 32 extending vertically and rotatably supported on the base 21, a sprocket 33 fixed to the lower end of the one-rotation shaft 32, and a sprocket 33 fixed to the lower end of the one-rotation 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.

and the rotation of the rotation shaft 32, the front jig IF (rotation shaft 5)
The transmission mechanism 35 for transmitting the signal is configured as follows. 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 connecting shaft 4O is also rotated. Of course, the rotation shaft 37 and the connection shaft 40 are installed so as to be located on the edge of one rotation shaft.

The connecting shaft 40 is connected to the rotating shaft 5 of the front jig IF.
be disengaged. That is, as shown in FIGS. 1O to 12, a cross-shaped connecting portion 5b is formed at the tip of the prebeat AIF rotating shaft 5, while a first connecting portion 5b is formed at the end of the connecting shaft 40.
014, as shown in FIG. 13, a box portion 4 having an engaging recess 40c into which the connecting portion 5b is fitted without rattling.
0a 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. Note that the rod 43 is connected to the connecting shaft 4 as shown in FIG.
It is fitted into an annular groove 40b formed on the outer periphery of the box portion 40a so as not to inhibit the rotation of the box portion 40a.

With the configuration as described below, by lowering the body W relative to the trolley while the connecting shaft 40 is displaced to the right in FIG. 7, the rotating shafts 5 of the front and rear jigs IF and IR are , is supported rotatably and immovably in the front-rear direction by intermediate struts 26 and 27. After this, the connecting shaft 40 (locking recess 40C) is connected to the rotating shaft 5 (the connecting portion 5 of the front jig IF).
b). 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.

In FIGS. 16 and 17, first, the notch 26a of the intermediate support 26 is formed in a semicircular shape so as 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. The shape is as follows. The engagement recess 40cm1 is opened in one side of the box part 40a, and when this opening is facing upward, the connection part 5b-1 is opened in the engagement recess 40c.
It is adapted to be engaged and disengaged from the vertical direction with respect to m1 (sliding of the connecting shaft 40 is not required).

Figure f518 and Figure 19 show the engagement recess 40cm2 formed in the box part 40a, as in Figures 17 and 18.
The connecting portion 5b-2 formed on the rotating shaft 5 of the front jig IF can be engaged and disconnected only when the The difference from the cases shown in FIGS. 16 and 17 is that the matching recess 40 cm2 has a shape corresponding to this quadrangle.

Of course, in the case of FIGS. 16 to 19.

In a state in which the connecting shaft 40 and the front jig IF can be engaged and disengaged (a state in which the engagement recess 40 cm 1.40 cm 2 faces upward),
Body W is in an upright position! ! ! (The roof panel of the body W shown in FIG. 7 is oriented in the - direction).

This is a device for changing the trolley at P2, P4, P7, P9, and pH, and examples thereof are shown in FIGS. 20 to 22. As shown in FIG. 22, this truck changing device is installed at a transfer station Sl where the truck movement trajectory R1 in the previous process and the truck movement trajectory R2 in the subsequent process are close to each other. The trolley changing device installed at the transfer station Sl is substantially composed of a lifter 51, as shown in FIGS. 20 and 21. 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.
The support legs 54 are each driven to expand and contract.
and has.

Each of the support legs 54 has a pair of front and rear support portions 54a spaced apart from each other in the moving direction of the truck.

In the above configuration, the trolley supporting the body W from the previous process is stopped at the transfer station S16.
When the trolley is stopped, the support legs 54 are extended from the base 53 located at the lowest position, and then the base 53 is moved upward. As a result, as shown in FIGS. 20 and 21, the body W on the truck is supported by the support portion 54a of the support leg 54.
While being supported by the side sill or floor frame of the W, it is lifted from the trolley and raised to a high position. After this, the cart for the previous process moves away from the transfer station Sl, and the cart for the post process moves to the new transfer station S.
located at l. 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 one-dot chain line in FIG. 21).

In this way, the body W is transferred from the front-process truck to the rear-process truck.

Of course, when transferring the body W, move the trolley back and forth.

It is preferable to firmly fix the trolley in a predetermined position in an immovable state using a positioning device or the like that clamps it from the 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 transferring the body W to the -H hanger using the lifter 51, the body W is transferred to the upper part of the trolley for post-processing using this hanger. , 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) Supplementary Explanation and Modifications Next, we will provide supplementary explanations and carts related to the present invention.
Modifications of the painting method, etc. will be explained in sequence.

■First, when removing dust in step P1, it is recommended to rotate the body W around the rotating shaft edge stand (second
(Refer to Figures (a) to (i)), as a result, the dust that has adhered to the inner surface of the body W, especially the surface that faces downward in the upright position, falls downward due to gravity, making it easier to remove dust. It will be possible to remove it. This prevents dust from falling during the rotation of the body W during the setting process and baking process, which is important in obtaining a high-quality painted surface.

■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.In other words, the quality of the final painted surface obtained after the top coating is determined by the quality of the intermediate coating. However, when the body W is rotated during the intermediate coating, the finishing level of the intermediate coating can be increased, and the conventional wet sanding becomes unnecessary. Moreover, if the body W is rotated during the top coat, the poor finish of the middle coat can be compensated for by the good finish of the top coat, without the need for wet sanding with the middle 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 it is visible, it will not be of equal support in terms of hue.

(4) Regardless of whether the bogie is running or stopping, switching between rotating and stopping the body W and changing the rotation direction can also be performed, for example, as follows. First, in the example shown in FIG. 7, a pair of first and second chains (chain 3
4), and each chain, respectively.
Set aside so that you can drive it as needed. With such a configuration, the rotation of the body W is controlled according to the following drive mode.

■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 - in this case, the body W does not rotate as the trolley moves).

[Phase]) Driving the first chain in one direction and freeing the second chain: In this case, even if the truck is stopped, the body W is rotated in one direction.

■ Drive the first chain in the other direction and move the second chain to 71
, 1- (if the chain is free and the second chain is driven in the other direction, it is the same): In this case, even if the truck is stopped +E, the body W is rotated in the opposite direction to that in the case (2) 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 movement of the trolley is a prerequisite for the rotation of the body W), the rack bar may be placed intermittently, or the position of the rack bar may be changed from left to right. By setting it arbitrarily, the body W can be rotated in any direction depending on the traveling position of the trolley, and the rotation of the body W can be stopped at any position.

■Modified examples of the trolley Figures 23 to 25 show modified examples of the trolley, and the same components as those shown in Figures 7 to 9 are given the same reference numerals and their explanations will be given. Omitted. In this embodiment, the rotational force for rotating the body W is extracted using the rotational force of the wheels 22 of one car. That is, an axle 46 is rotatably supported on the base 21 via a bearing 45, and the wheels 22 are fixed to each end of the axle 46. Then, bevel gears 47 and 1 fixed to the axle 46
A bevel gear 48 attached to the lower end of the rotating shaft 32 meshes with the rotating shaft 32 . Thereby, when the wheels 22 are rotated, the body W is rotated via the rotating shaft 32.

In addition, a clutch 49 is provided in the middle of the rotating shaft 32,
The advantage of this embodiment is that the relationship between the running of the trolley and the rotation of the body W can be appropriately severed.
This eliminates the need for a long chain such as the chain 34 shown in FIG.

■Preferred aspect of baking furnace In the baking process of P6 and PI3, the rotation of the body W is
The rotating shaft rim that extends in the front-rear direction of the body W is the body W.
The conveyance methods of the bodies W are set to be perpendicular to each other, so that the number of bodies W that can be stored in the baking furnace can be increased as much as possible.

In other words, this solves the problem that if the rotating shaft edge stand that extends in the front-rear direction of the body W is extended as it is in the conveying direction of the body W, the length in the conveying direction that occupies one inner part of the body W becomes extremely long. It is something.

First, as shown in FIG.
The body W is rotated vertically by 90" by 90" and its posture is changed so that the vehicle width direction becomes the transport direction. After this, the body W is carried into the baking furnace 62. Of course, the rotation of the body W in the baking furnace 62 is as follows. - It is carried out centering around the rotating shaft rim that extends in the front-rear direction (the rotating shaft rim is orthogonal to the conveyance method of the body W).

In order to efficiently rotate the body W in the baking furnace 62, that is, in a space-saving manner, it is preferable to do so as follows.That is, on the left and right side wall portions of the baking furnace 62, there are first and second grooves extending in the conveyance direction. A pair of rack bars 63F, 6
3R is fixedly arranged, and the il rack par 63F has the first
A gear 65F fixed to the rotating shaft 64F is engaged with the second rack 83H, and a second gear 65F fixed to the second rotating shaft 64H is engaged with the second rack 83H.
Gear 65R is engaged. The front part of the body W is removably connected to the first rotating shaft 64F via a front jig IF, and the rear part of the body W is detachably connected to the second rotating shaft 64H via a rear jig IR. Can be freely connected. Of course, both rotation shafts 64F and 64R are located above the rotation axis.

An endless chain 67 is disposed along the second rack 63H, and the chain 67 has supporting portions 68 each consisting of a pair of front and rear clamping pieces at predetermined intervals.
A comparison is made. The second rotating shaft 64R is held between the supporting parts 68 from the front and rear in the conveyance direction. This chain 67 is operated by a motor (not shown), and is installed at a location away from the baking furnace 62 from the viewpoint of explosion protection. Note that the support portion 68 of the chain 67
A support bracket 69 for preventing drooping is provided at least below the clamping portion so that the portion that clamps the second rotating shaft 64R from the front and rear directions does not sag.

In addition, 70 in FIG. 27 and FIG. 28 is a hot air circulation path,
A fan 71 connected to this blows hot air blown from the upper part of the baking furnace 62 out from the bottom of the baking furnace 62.

In the above configuration, the second rotating shaft 64R receives a pressing force in the conveying direction by the drive of the chain 67 via each support portion 68. Due to this pressing force, not only the if rotation shaft 64R but also the body W and the first rotation shaft 64
F is also rotated and driven in the transport direction.

(2) Preferred aspect of paint spraying Process P3 corresponds to PLO, but since the only difference is in the paint used for intermediate coating and -1-coating, the explanation will focus on PLO.

In the painting line shown in FIG. 35, the painting line is divided into stations from engineering to station in the direction of conveyance of the body W, so the flow is divided for each station.

At Station I, the body W that has been continuously transported is transferred to tact transport. Further, as shown in FIG. 36, a touch-up jig 80 is used to maintain the bonnet 95 and trunk lid 96 in an open state. In addition, FIG. 36 shows a relationship in which the body W is not rotated, and a conventional transport trolley D' that does not have a rotation function.

Station ■ The first and second central painting robots 81 and 82, which are installed on both sides of the first and second painting stages, are used to paint the inner surface of the body W. In addition to painting the corner painting parts 1iLi and a2, the first and second corner painting robots 83 and 84 paint the left and right halves of the front and rear ends of the body W, C3 and C.
2 is to be painted. The first and second corner painting robots 83.84 are those that paint the corners BBC1 and C2 located away from the painting parts a1 and a2 of the first and second central painting robots 81.82. They are placed on both sides.

In other words, in the case of 1 illustration, wS1 center painting robot) 81
is responsible for painting the first central part a1 of the center front cloth, the second central part painting robot 82 is responsible for painting the second central part a2 on the rear left of the center, and the first corner painting robot 83 is responsible for painting the second central part a2 on the front left. First corner C! The second corner painting robot 84 is responsible for painting the second rear right corner C2.

Station■ This is a post-stage painting station for painting the inner surface of the body W. Similar to the pre-stage painting station ■, the third and fourth central part painting robots 85 and 86 installed on both sides paint the central part of the body W. The remaining diagonal painted part a3. A4 is painted, and the third and t54 corner painting robots 87 and 88 paint the remaining halves of the left and right parts of the front and rear ends of the body W, c3 and C4.
It is intended to be painted. The third and fourth corner painting robots 87 and 88 perform painting C3 and C4 at positions away from the painting parts a3 and a4 of the third and fourth central painting robots 85 and 86, respectively. It is arranged.

That is, the third central part painting robot 85 takes part in painting the third central part a3 on the left side of the center curve, and the fourth central part painting robot 8
6 is in charge of painting the fourth central part a4 on the rear right of the center, the third corner painting robot 87 is in charge of painting the third corner C3 of the front, and the fourth corner painting robot 88 is in charge of painting the rear left corner C3. Fourth corner C4
This means that each person will be responsible for painting the parts.

The above-mentioned front-stage and rear-stage painting stations ■ and ■ are fixed stations that paint the interior surfaces of the doors 91, 92, engine room 93, and trunk room 94 of the body W, and each central painting robot 81, 82, 85, and It has opening/closing means (not shown).

By sharing the painting at stations ■ and ■ as mentioned above,
Spraying allows efficient painting while preventing interference between painting robots.

Station ■ Transfers body W from tact transport to continuous transport. Further, correction painting is performed by manual painting, and this correction painting is mainly performed on the boundary position between the inch part and the outer part of the body W. Also, engine room 93
and bonnet 9 for painting trunk room 94.
5 and the touch-up jig 80 that had opened the trunk lid 96 is recovered, and the door 91.92 is newly opened.
．． A bonnet 95 and a trunk lid 96 are fixed and held using a locking jig (not shown) so as not to open. Note that this fixation is to prevent each of the above-mentioned parts 91, 92, 95, and 96 from opening when the body W is rotated later.

Station V This is the exterior painting of the body W. Of this exterior surface, the body W
Paint is sprayed onto the top and side surfaces of the This spraying is carried out by a fixed or reciprocating automatic paint sprayer. Please note that this spraying on the top and side surfaces is done in two parts.
This spraying at station V corresponds to the first spraying. Therefore, the thickness of the paint sprayed at this station V is made sufficiently thin to be within the sag limit.

Station ■ Estimated correction by manual painting. That is, this is done in anticipation of areas that will require correction after the exterior painting at the next stations (1) and (2). By performing this estimated correction, after spraying the paint to a thickness that exceeds the sag limit at the next stations ■ and ■, the next drying process (setting process) in which the body W is immediately rotated can be started. can do.

Station ■ The exterior of the body W except for the side and top surfaces is painted. This painting is done by painting robot 100.
, lot. Since the paint is sprayed only once on this part, the thickness of the sprayed paint is greater than the sag limit.

Station ■ The second spraying is performed on the top and side surfaces of the body W. This spraying is done in an automatic spray machine in the same manner as described in Station V above. By spraying the paint here, the thickness of the paint on the top and side surfaces also exceeds the sag limit.

In order to minimize the number of paint guns used for automatic painting at stations V and ■, it is preferable to spray using the rotation of the body W. In other words, the painting guns spray paint in the upward, left, and right directions. It is preferable to change the surface to be coated using the rotation of the body W only from one predetermined direction from the right side.

29 to 31 show the case where paint is sprayed only from above. In this case, fix the mounting bar 57 to the top wall of the painting booth, and
A plurality of painting guns 58 are attached to the. Each of the painting guns 58 is configured to spray paint downward.

In the above-described configuration, the body W, which is horizontally rotatably supported by a single carriage, is first sprayed with paint on its top surface (Fig. 29) and then rotated around the shaft edge stand. With the body W rotated 90", paint is sprayed on the right side of the body W (Fig. 30). Subsequently, with the body W rotated 180@ around the rotating shaft edge stand, the left side of the body W is sprayed. Paint is sprayed onto the surface (Figure 31).

Figures 32 and 33 show an example in which paint is sprayed only from the - side. That is, a mounting bar 57 is provided upright on the left side of the truck, and a plurality of painting guns 58 are mounted on this mounting bar 57. In this example, for example, paint is first sprayed on the left side of the body W (the third
After that, paint is sprayed onto the top surface of the body W while it is rotated 90' around the rotating shaft edge stand (Fig. 2).
3), paint is sprayed onto the right side surface of the body W while the body W is rotated 1806 degrees around the rotating shaft edge (FIG. 34).

(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 particular, since the object to be coated is rotated in order to prevent paint blurring during both the setting and baking steps, where paint blurring is likely to occur, the resulting painted surface is completely smooth and has no blurring. Become something.

[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. FIG. 14 is a sectional view taken along the line X14-X14 in FIG. 1θ. 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.
-Xl S-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 cross-sectional view taken along the line X18-Xla, and FIG. 19 is a side cross-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. Figures 23 to 25 show modified examples of the trolley.
3 is a side view, FIG. 24 is a simplified perspective view of the main part, and FIG. 25 is a sectional view showing the state below the bogie running path. FIG. 26 is a simplified plan view showing the state of conveyance of the body to the vicinity of the baking furnace. FIG. 27 is a front sectional view of the baking furnace. FIG. 28 is a partially omitted side sectional view of the baking furnace. FIGS. 29 to 31 are front views showing an example of painting the top and side surfaces of the body. FIGS. 32 to 34 are front views showing examples of painting the top and side surfaces of the body. FIG. 35 is an overall layout diagram showing a specific example of spraying paint. Figure i36 is a side view showing the main parts of Figure 35. P1 to P13: Process W: Body fL 24 Rotation axis: Transport trolley IF, IR: Rotation jig

Claims (1)

[Claims] (1) A painting process in which the paint is applied to the object to be coated, a baking process in which the applied paint is dried by baking, and the paint is applied at a temperature lower than that in the baking process between the painting process and the baking process. and a setting step for drying, in the painting step, the paint is applied to a thickness greater than the sag limit, and in the setting step and the baking step, the object to be coated is horizontally applied. A painting method characterized by rotating.