JPH0523263Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention relates to a body rotation device for drying paint.

(Prior art and its problems) When painting the outer surface of an automobile body, there are a preparatory process to remove dust adhering to the object to be painted, a process to apply paint to the object to be painted, and a process to remove the applied paint. and a drying step of drying. This drying process
For example, thermosetting paints are carried out in two stages: a setting process and a baking process.The setting process is performed before the baking process at a temperature lower than that of the baking process, such as room temperature or 40° to It is carried out in a temperature atmosphere of 60℃ (the baking temperature in the baking process is usually around 140℃).

The automobile body is normally transported through the preparation process, painting process, and drying process while being transported by means of transportation such as a trolley, but the posture of the object to be coated remains the same in each process. It is being done.

By the way, one criterion for evaluating the quality of a painted surface is smoothness (flatness), and the greater the smoothness, the smaller the degree of unevenness on the painted surface, and the better the 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, paint sag is a factor that impairs the quality of painted surfaces. This sagging is caused by the applied paint flowing downward under the influence of gravity, and the cause of this sagging is that the thicker the paint that is applied at one time, the more likely it is to sag. Since this is ultimately due to the effect of gravity, it tends to occur on surfaces of the object to be coated that extend in the vertical direction, that is, so-called vertical surfaces.

Therefore, on the horizontally extending surfaces of the object to be coated, ie, the so-called lateral surfaces, where "sagging" of the paint does not pose 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 and vertical surfaces is the same, the unevenness on the horizontal surface will be reduced due to slight flow of the paint that does not cause sagging, and the unevenness will be reduced on the vertical surface. This results in a smoothness better than that obtained in .

From the above-mentioned point of view, conventionally, in order to obtain a paint surface as smooth as possible while preventing the paint from sagging, painting was carried out using a paint with as little fluidity as possible. The so-called "sag limit" where paint "sags" on vertical surfaces is
For example, with thermosetting paints, the maximum coating film thickness was about 40 μm. More specifically, paint sag tends to occur during the setting process and baking process, especially during the baking process, and the thickness of the paint applied during the painting process is determined to prevent sagging during this period. , the maximum value of this determined thickness, that is, the sag limit value is about 40 μm. Therefore, in order to obtain a painted surface with even greater absolute smoothness, conventional painting methods require repeating the series of steps from the painting process to the baking process multiple times, such as applying two coats. It was necessary to do it.

The present invention was developed in consideration of the above circumstances, and it is a body rotation device for drying paint that allows a smoother painted surface to be obtained with the same paint film thickness. The purpose is to provide.

(Means and effects for solving the problem) This invention basically improves the fluidity of the paint by appropriately changing the direction of gravity acting on the paint applied to the object. This is actively utilized to obtain a coated surface with greater smoothness for the same coating thickness. in particular,
It has the following configuration, that is, a conveying means for moving the paint drying process, and a means installed in the conveying means that can freely rotate around a substantially horizontal axis an automobile body coated with paint to a thickness exceeding the sag limit. a pneumatic drive means provided on the conveyance means for rotationally driving the automobile body supported by the support means; and a pneumatic drive means provided on the conveyance means and supported by the support means. and speed regulating means for controlling the speed of the automobile body so that the automobile body is rotated at a constant speed when the automobile body is driven by the driving means.

As described above, with the rotating device according to the present invention, the direction of gravity acting on the paint applied to the body is changed by rotating the body, which causes the paint to "sag". It will dry without any problem. In other words, the film thickness of the paint applied per coat can be made much thicker than conventionally, and an extremely good coated surface with smoothness that far exceeds the level conventionally considered to be the limit can be obtained.

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 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 that of conventional painting methods. The amount of paint used can be reduced by the amount that can be made thinner.

Of course, a paint that causes "sag" even in a thin film can be obtained by reducing a predetermined proportion of components that inhibit fluidity in conventional paints.

In addition, the present invention utilizes air pressure as the driving force generation source for rotationally driving the body, making it possible to deal with explosion-proofing during the drying process, which is a particular problem. Furthermore, in the present invention, since the automobile body is rotated at a constant speed by the speed regulating means, a situation where paint applied to a thickness exceeding the sag limit is caused to sag due to rotational fluctuations can be avoided. is also reliably prevented.

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

Overall Overview FIG. 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 P4.

First, the body W, which has been undercoated by electrocoating in a known manner, is held on a truck D and sent to a preparatory step P1. In this preparatory step P1, dust inside and outside the body W is removed by, for example, air blowing or vacuum suction. Next, after paint is sprayed onto the body W in step P2, the paint is dried in setting step P3 and baking step P4.

If steps P1 to P4 are for intermediate coating, step P
After step 4, the body W is sent to the top coating process. Further, when the steps P1 to P4 are for topcoating, the body W is transported to an assembly line as is known.

Removal of Dust Dust removal in step P1 is preferably performed while rotating the body W around the horizontal axis l, as shown in FIG. That is, for example, first, the rotation of the body W is stopped in the state shown in FIG. 2a and dust is removed, and then the attitude of the body W is changed to the state shown in FIG. 2b and the body W is stopped at this position. , garbage removal is performed again. In this way, c, b in Fig. 2...
...i, dust is removed while the body W is rotated intermittently.

In this way, by removing dust while rotating the body W, it is possible to remove dust adhering to the closed cross section of the roof panel inner surface corner or side sill of the body W, for example, by rotating the body W. It becomes possible to completely remove even the garbage that does not fall.

Spraying and Drying of Paint First, the paint is sprayed in P2 so that the thickness of the paint film is equal to or greater than the sag limit. In other words, in conventional thermosetting paints, the maximum thickness of the paint that does not cause "sag", that is, the sag limit value, is about 40 μm, but in process P2, the thickness is far greater than this sag limit of 40 μm. The paint is sprayed to form a thick film (eg 65 μm).

After this P2, the process moves to a setting step P3. In this setting step P3, as shown in FIG. 2 a to i, the body W is rotated around a rotation axis l extending in the horizontal direction. It is said to grow. Although the temperature atmosphere in this setting step P3 is set at room temperature in the embodiment, it may be set at an appropriate temperature within a temperature range lower than the temperature atmosphere in the next baking step P4, such as 40 DEG to 60 DEG C. Of course, this setting process P3 is
This is to volatilize the low boiling point content in the paint in advance, thereby preventing the generation of pinholes on the painted surface due to the rapid volatilization of the low boiling point content in the next baking step P4.

In the baking step P4, the paint is baked in an atmosphere at a temperature of 140° C., for example. This P
4, the body W is rotated in the horizontal direction as in the setting step P3.

Due to the horizontal rotation of the body W at P3 and P4 described above, 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 body W is rotated in both steps P3 and P4 is because a thermosetting paint that causes sagging is used in both steps P3 and P4, and in the case of powder paint, it is rotated in the baking step P4. In the case of a two-component curing type paint, it is sufficient to perform this rotation only during the setting process.

Note that it is preferable to change the cart D between P2 and P3 so that paint does not adhere to the cart D used in the drying process in P3 and P4. That is, in P2, a considerable amount of paint will be sprayed onto the cart D, but if the cart D with this paint adhered is used as is and transferred to the drying process, the paint adhered to the cart D will be sprayed onto the cart D. D
This is because as the paint runs, a considerable amount of paint may peel off and become dust, which may impair the quality of the painted surface.

Relationship between coating film thickness, sagging limit, smoothness, and horizontal rotation Figure 3 shows the influence of coating film thickness on the sagging limit when focusing on thermosetting paints. In this Figure 3, the coating film thickness is
Three cases are shown: 40 μm, 53 μm, and 65 μm. In the case of any of these thicknesses, "sagging" occurs both at the beginning of the setting process and the beginning of the baking process.
It is understood that a peak of . In addition, the sag limit is the value when the sag normally occurs at a rate of 1 to 2 mm per minute (the painted surface is considered to be defective if the sag occurs at a rate of 2 mm/min or more when visually observed); The maximum film thickness that can be obtained in this range is around 40 μm 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 a state in which the body W is not rotated (conventional painting method). Fig. 4B shows the case where the body W is continuously rotated in the same direction (Fig. 2a, b, c).
...take the posture in the order of i and return to position a). Further, FIG. 4C shows a case where the body W is rotated 90 degrees and then reversed (forward and reverse rotation between FIG. 2 a and c). Figure 4 D shows the case where the body W is rotated 135° and then reversed (Figure 2 a and d).
forward and reverse rotation). Figure 4 E shows body W at 180°
The case where the rotation is reversed after rotation is shown (second
Forward/reverse rotation between figures a and e).

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) and not to rotate it (Fig. 4 A).
A product with greater smoothness can be obtained. In addition,
As is known, the IG at the image sharpness in Figure 4
(Image gloss) indicates the ratio of sharpness to the mirror surface (black glass) as 100, and PGD indicates the smoothness of the painted surface as the discrimination of the reflected image decreases from 1.0. This is a decreasing value.

The test conditions for the data shown in Figures 3 and 4 are:
The test conditions are as follows, but these test conditions are for performing topcoating in P2.

a Paint: Melamine alkyd (black) Viscosity: 22 seconds/20℃ with food cup #4 b Coating machine: Minibell (16000 rpm) Shaping air...2.0Kg/cm ² c Discharge amount: Sprayed in two parts , 1st time...100c.c./min 2nd time...150~200c.c./min d Setting time: 10 minutes x room temperaturee Baking conditions: 140℃ x 25 minutesf Base smoothness: 0.6 (PGD Value) (Intermediate coating, on PE tape) g Rotating or reversing operating range: Setting (10 minutes) to baking (10 minutes) h Object to be coated: Painted on the side of a rectangular cylinder with a side of 30 cm, supported rotatably at the center i Rotation speed of object to be coated: 6rpm, 30rpm, 60rpm
However, there was virtually no difference due to the difference in rotational speed.If the paint is a two-component type that uses a main resin and a curing agent, sagging may occur only in the setting process P3. In addition, if the paint is separated paint, sagging occurs only in the baking process P4, so the rotation of the body W is during the setting process P3 where this sagging occurs.
It is sufficient to perform this only in the printing process P4 or only in the baking process P4. Further, in the case of powder coatings, since they do not contain solvents, a setting step is not necessary.

Rotation Jig Next, a specific example of a jig used to support the body W in a horizontally rotatable manner relative to the cart D will be described.

FIG. 5 shows a front jig 1F attached to the front part of the body W. This jig 1F 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, a connecting bar 4 that connects the left and right pair of stays 3, and a connecting bar 4. It has an integrated rotating shaft 5. The bracket 2 portion of such a jig 1F 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 mounting a bumper (not shown) is usually welded to the front side frame 11, the bracket 2 is attached to the bracket 12 on the body W side using bolts (not shown). and fix it.

On the other hand, a rear jig 1R attached to the rear part of the body W is shown in FIG. This rear jig 1R has the same configuration as the front jig 1F,
Components corresponding to this front jig 1F are given the same reference numerals. The body W of this rear jig 1R
For installation, attach the bracket 2 to the body W.
Floor frame 1 as a strength member at the rear end
This is done by fixing it to 3 with bolts. Of course, since a bumper is generally attached to the rear end of the floor frame 13, a bracket for attaching the bumper is welded in advance, so this bumper attaching bracket is used to attach the rear jig 1R. You can also do it.

When the front and rear jigs 1F and 1R 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 becomes the rotational axis l of the body W, and preferably this rotational axis l
passes through the center of gravity G of the body W (see FIG. 7). Note that since the rotational axis 1 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 front and rear jigs 1F and 1R are specially prepared in advance according to the vehicle type (type of body W).

Dolly This is a dolly that is used at least in P1, P3, and P4 and has a function of rotating the body W.

In FIG. 7, the truck D has a base 21, and the wheels 22 attached to the base 21 are mounted on the road surface 21.
be run on top. This base 21 includes one front support 24, two intermediate supports 25 and 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 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 1F, while its rear part is
It is rotatably supported by the rear support 27 using the rear jig 1R.

The front and rear jigs 1F and 1R (rotary shafts 5 of them) can be freely engaged with and disengaged from the columns 26 and 27 from above and below, and the rear jig 1R is immovably engaged in the direction of the rotation axis l. Ru. For this reason, the intermediate strut 26 has a notch 26a that opens on its upper end surface (see FIG. 9), while the rear strut 27 has a notch 27a that opens on its upper end surface (see FIG. 9). (See Figure 10). Both notches 26a and 27a are
The size is such that the rotating shafts 5 of the jigs 1F and 1R can fit therein. A flange portion 5a is formed on the rotating shaft 5 of the rear jig 1R, while a rear support 27
A notch 27b having a shape corresponding to the flange portion 5a is formed in the flange portion 5a. As a result, the rear jig 1
R is engaged with and disengaged from the notches 27a and 27b of the rear strut 27 from above and below, and is made immovable in the longitudinal direction relative to the rear strut 27 by the stopper action of the flange portion 5a. Incidentally, the rotational force is applied to the body W through the rotation shaft 5 of the front jig 1F, and therefore a box portion 5b (see FIG. ) is formed.

A stay 29 projects downward from the base 21, and a traction wire 30 is connected to the lower end of the stay 29. This wire 30 is of an endless type and is driven in one direction by a motor (not shown), thereby driving the cart D in a predetermined transport direction (in the direction of the arrow in FIG. 7). 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 using a pneumatic motor 31 for explosion-proof measures.
The unit U including the unit U is installed on the front support 24, and between the output shaft 31a of the motor 31 and the rotating shaft 5 of the front jig 1F, from the front side to the rear side in the trolley running direction,
A speed regulating mechanism 32 and a continuous shaft 33 are sequentially provided.

The continuous shaft 33 is capable of being engaged with and detached from the rotating shaft 5 of the front jig 1F. That is, as shown in FIG. 11, a cross-shaped connecting portion 33a is formed at the rear end of the connecting shaft 33, while a cross-shaped connecting portion 33a is formed at the tip of the rotating shaft 5 of the front jig 1F as shown in FIG. As shown in FIG.
A box portion 5b is formed.

Therefore, by sliding the connecting shaft 33 using, for example, a pneumatic cylinder, the box portion 5b (engaging recess 5c) and the connecting portion 33b are engaged and disengaged, and the connection occurs when they are engaged. Axis 33 and rotation axis 3
3b can be rotated together. Further, displacement in the axial direction of the connecting shaft 33, which will be described later, is compensated for.

The speed regulating mechanism 32, as shown in FIG.
A disc 33b integrally provided at the front end of the connecting shaft 33
and a friction plate 34, one end of which is in contact with the front surface of the disc 33b. The friction plate 34 is displaceable in the extending direction of the rotational axis l of the body W, and its rear end is linked to a rack 36 via a tension spring 35, and this rack 36 is connected to the pinion 3.
7, it can be displaced in the direction of the rotational axis l. Therefore, for example, by rotating the pinion 37 according to the rotational speed of the body, the load on the disc 33b is adjusted, and thereby the rotational speed of the body W is adjusted. The connecting shaft 33
The connection between the output shaft 3 and the motor 31 is the output shaft 3 of the motor 31.
A disk 31b is provided at the tip of 1a, and this disk 3
1b and the disk 33b of the connecting shaft 33 are connected via links 38, 39 and a mass 40 provided between these links 38, 39. That is, one end of one link 38 is rotatably attached to the disc 31b, and these links 38, 39
The other end is rotatably attached to the mass 40. Therefore, as the rotational speed of the motor 31 increases, the centrifugal force acting on the mass 40 displaces the connecting shaft in a direction closer to the motor 31,
The disk 33b comes into pressure contact with the friction plate 34, and rotation at a predetermined constant speed is soon guaranteed.The displacement of the connecting shaft 43 is determined by the connection portion 33a of the connecting shaft.
and the box portion 5 of the rotating shaft 5 in the front jig 1F.
b.

As shown in FIG. 3, the motor 31 has a rotating body 42 that is eccentrically arranged inside a casing 41, and a plurality of vanes 43 appear and retract at intervals around the circumference of the rotating body 42. freely set up,
A working chamber 44 is defined by these vanes 43,
As a result, the working chamber 44
The volume is made variable. The casing 41 is provided with an inlet 41a on the side where the volume of the working chamber 44 is increasing, and an outlet 41b is provided on the side where the volume of the working chamber 44 is decreasing. 4
5 and 46 are connected, and the pipes 45 and 46 are integrated into the pipe 47 in the middle, as shown in FIG.
A supply passage 47b and a discharge passage 47c are formed by the partition wall 47a and open to the outer wall of the motor unit U. External piping 48 for this
is a flexible pipe, and this external pipe is suspended from a rail 50 provided above the running area of the truck D via a hook 49, and the hook 49 located at the front end
is integrated with a support 51 extending upward from the front support 24, and the external piping 48 can travel together with the truck D. The upstream end of the external piping 48 is connected to a high-pressure air supply source (not shown), and the downstream end is a joint portion 52 that connects the motor unit U.
It is detachably connected to the

Although one embodiment of the present invention has been described above, the present invention is not limited to this and includes the following modifications.

(1) In the above embodiment, the body W is rotated in one direction, but the body W may be reversed within a predetermined angle range.

Here, the body W may be reversed, for example, as follows. That is, when considering one cycle of rotation of the body W that involves reversal using the position a in FIG. Just rotate the angle. For example, if both of the above predetermined angles are 90 degrees, the change in the posture of the body W is as follows: a→b→c→b in FIG.
→a, i→h→g→h→i, a makes one cycle. Of course, inversion is performed in the above states c and g. As another example, if both the above predetermined angles are 135°, one cycle is a→b→
c→b→c→b→a, i→h→g→f→g→h
→i, a. And the reversal at this time is
It is done when d and f.

Of course, the above-mentioned predetermined angle may be determined so that the direction of gravity acting on the paint (particularly paint applied on a vertical surface) is changed, and the shape of the object to be coated, especially the position of the corner, is taken into consideration. . Therefore, the second
The manner of rotation accompanied by reversal can be set as appropriate, such as rotating it sequentially from figure a to b, c, and d to i (after rotating it by 360 degrees), and then rotating it again by 360 degrees in the opposite direction.

By performing such reversal, it is possible to prevent a large amount of paint from concentrating on the corners of the object to be coated, thereby preventing a situation where the coating film becomes extremely thick only at these corners.

(2) An air cylinder may be used instead of the motor 31.

(Effects of the invention) As is clear from the above, the invention has the following effects:
By applying paint that is thicker than the sag limit and rotating the automobile body, it is possible to obtain a high-quality painted surface that is smoother than conventional paint with the same paint thickness. In addition, since air pressure is used as the driving force generation source, it can be advantageous in terms of explosion-proof measures.

Furthermore, in the present invention, the rotation of the automobile body to prevent paint from dripping during the painting drying process is carried out while the automobile body is being conveyed by the conveying means, which is preferable in terms of increasing the production rate. Become.

By absorbing the rotational fluctuations of the pneumatic motor by the speed regulating means, the automobile body is rotated at a constant speed, thereby preventing paint from sagging that would otherwise occur due to rotational fluctuations of the automobile body. It is also preferable to do so.

[Brief explanation of the drawing]

FIG. 1 is an overall process diagram showing an 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. Figure 3,
Figure 4 is a graph showing the relationship between paint thickness and sag, paint surface smoothness, and rotation. 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 transporting trolley in which the body can be rotated. FIG. 8 is a side cross-sectional view showing the joint portion between the rotation jig and the truck. FIG. 9 is a sectional view taken along the - line in FIG. 8. FIG. 10 is a sectional view taken along the line -- in FIG. 8. Figure 11 is similar to Figure 8.
Cross-sectional view taken along the XI-XI line. FIG. 12 is a configuration diagram of the speed regulating mechanism.
FIG. 13 is a configuration diagram of the motor. FIG. 14 is a sectional view taken along the line X--X in FIG. 13. P1 to P4...Process, W...Body (subject to be coated),
l...Rotation axis, D...Transportation trolley, 1F, 1R
... Rotating jig, 21 ... Base, 31 ... Air motor, 32 ... Speed regulating mechanism.

Claims (1)

[Scope of Claim for Utility Model Registration] A transport means D for moving the paint drying steps P2, P3, and P4, and a transport means D provided on the transport means D for transporting an automobile body W coated with paint to a thickness exceeding the sag limit approximately horizontally. Supporting means 26, 2 rotatably supported around axis l
7, provided on the conveying means D, and supporting means 2
a pneumatic drive means 31 for rotationally driving the automobile body W supported by the support means 2 and 6, 27;
6, 27, when the driving means 31 drives the automobile body W, the speed regulating means 32 controls the speed so that the automobile body W is rotated at a constant speed;
A body rotation device for drying paint, comprising: