JPH0248074A - Painting method - Google Patents

Abstract

PURPOSE:To improve the smoothness of a coated surface by previously balancing a rotating system for a material to be coated in such a manner that the centroid of the system exists on a prescribed rotating axial line by taking the weight of the paint applied above the sag threshold into consideration prior to a painting stage. CONSTITUTION:The material W to be coated such as automobile body in mounted on the horizontal revolving axis of a truck D and is coated with the paint to the thickness above the sag threshold in the painting stage P2. The low boiling point component in the paint is evaporated in a setting stage P3 while the material is kept rotated. The paint is cured and baked until the sag does not arise any longer in a baking stage P4. The rotating system for the material W is previously so balanced that the centroid thereof is positioned on the rotating axial line of the truck D by taking the weight of the paint to be applied thereon is taken into consideration in the stage P1 before the painting stage P2 in order to smoothly rotate the material around the horizontal axial line to prevent the sag of the paint. The generation of the sag of the paint is prevented by smoothly rotating the material to be coated in such a manner, by which the coated surface having the better smoothness is obtd.

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, by spraying, there are two steps: a preparation process to remove dust adhering to the object, and a process of spraying and applying the 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. It is carried out in an atmosphere with a temperature of 140°C to 60°C (the baking temperature in the baking process is usually around 140°C).

The object to be coated is usually transported by means of transport such as a trolley and passes through the preparation process, coating process, and drying process described in 1 above. It is carried out while being retained.

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, paint sag is a factor that impairs the quality of painted surfaces. This sagging is caused by the applied paint flowing downward due to the force of gravity.
The thicker the paint film that is applied at one time, the more likely it is that "sagging" will occur.The cause of this "sagging" is, after all, the effect of gravity. This tends to occur on vertical surfaces. For example, when considering the body of a car as the object to be coated, sagging is less likely to occur on the side surfaces such as the bonnet and trunk lid, but it is more likely to sag on the fenders, which are the vertical surfaces.

Therefore, on surfaces extending in the horizontal direction of the object to be coated, that is, so-called lateral surfaces, where the amount of "sagging" of the paint is less of a problem, the thickness of the paint applied can be made more convenient 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 thickness of about 40 μm for conventional thermosetting paints. More specifically, "sagging" of thermosetting paints tends to occur at the beginning of the setting process and at the beginning of the baking process, especially at the beginning of the baking process. The thickness of the paint to be applied is determined, and the maximum value of the determined thickness, that is, the sagging limit value, is approximately 40 μm. 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.

(Objective of the Invention) Therefore, an object of the present invention is to provide a coating method that allows a coated surface with better smoothness to be obtained with the same paint thickness.

(Structure and operation of the invention) In order to achieve the above-mentioned object, the present invention has the following structure. That is, in a coating method that includes a coating step of applying paint to an object by spraying and a drying step of drying the applied paint, the thickness of the paint sprayed onto the object to be painted is In the drying step, the coating material is rotated around a predetermined axis of rotation extending in a substantially horizontal direction until the paint applied to the coating material is cured to the point where it no longer sag. Before the painting process, balancing is performed in advance so that the center of gravity of the object to be coated is located at the predetermined rotation axis -1, taking into account the weight of the paint to be applied in the painting process. , with a configuration like this.

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 to be coated around the approximately horizontal axis, so that the paint does not "sag". It will be dried without any 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, 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.

In the present invention, the center of gravity of the object to be coated is aligned with the predetermined axis of rotation.
This rotation can be performed smoothly with as little force as possible. Especially,”−
Since the alignment between the center of gravity and the axis of rotation is done taking into consideration the state in which the paint is actually applied, imbalances caused by the paint are reliably prevented. Since this balancing is performed in advance before the painting process, this balancing can be done with plenty of time without being subject to time constraints from the viewpoint of paint sag after painting. Of course, it is preferable that the object to be coated be rotated smoothly in order to prevent paint from sagging due to rotational fluctuations.

Here, the paint may be sprayed by electrostatic coating. In addition, paint sag refers to the movement of paint that can be visually confirmed when the paint is left in the sprayed state (it appears as streaks when the paint hardens), and is generally about 2 mm. Sagging is considered to have occurred when movement of the paint is confirmed. Therefore, spraying paint to a thickness that exceeds the sag limit means spraying the paint to a thickness that will cause at least 2 mm of paint movement if left as is, and the more fluid the paint used, the more likely it will sag. The critical thickness becomes smaller. To achieve a thickness that exceeds this sag limit, it may be sprayed once (1
(stage blowing), the final thickness may exceed the sag limit by spraying two or three times or more (multi-stage blowing). Furthermore, the rotation of the object to be coated around the approximately horizontal axis should be done in such a way that the paint does not move significantly due to the action of gravity. The rotation may be performed continuously or intermittently in one predetermined direction until the material is cured, or the forward and reverse rotations may be performed continuously or intermittently. Regarding the rotation angle range of the object to be coated, the direction in which gravity acts should be reversed for any part where the paint is sprayed to a thickness above the sag limit, and 270 degrees is sufficient. be. The axis of rotation of the object to be coated may be inclined within a range of about 30 degrees with respect to the true horizontal axis, and this axis of rotation may also be swung.

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

3D Riyam I FIG. 1 shows the entire process when painting an automobile body W as an object to be painted, and each process is shown as P1 to P4.

First, the body W, which has been coated with at least an undercoat by electrocoating as is known, is sent to the balancing step PI while being held on a trolley. In this balancing step PI, as will be described later, the center of gravity of the body W is adjusted to coincide with its axis of rotation, taking into account the weight of the paint to be applied in the next painting step P2. After that, paint is sprayed onto the body W in a painting process P2. Then, the drying of the paint is the setting process P.
3 and a baking step P4.

If the steps PI to P4 are for intermediate coating, the body W is sent to the top coating step after step P4. Also, process P
If I to P4 are for topcoating, the body W is transported to an assembly line in a known manner.

・Noki・C1 B First, the paint is sprayed in P2 so that the thickness of the paint film exceeds 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 much greater than this sag limit of 40 μm. To make a thick coating (e.g. 65μm)
Paint is sprayed so that Of course, the sag limit film thickness can be set to a sufficiently small value, for example, 30 μm (adjusting the content of the solvent and anti-sag agent), so the absolute thickness of the paint to be applied is a particular problem in the present invention. This is not true.

In the setting step P3, the body W is rotated in the horizontal direction as shown in FIGS. 2(a) to 2(i). That is,
The body W is rotated around a rotation axis β that extends in the horizontal direction, and in the embodiment, this rotation axis β extends in the front-rear direction of the body W. Note that the temperature atmosphere in this setting step P3 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. It is possible. Of course, this setting process P3 is to volatilize the low boiling point content in the paint in advance, and this will prevent pinholes from forming on the painted surface due to the rapid volatilization of the low boiling point content in the next baking process P5. is prevented.

In the baking step P4, the paint is baked in an atmosphere at a temperature of 140° C., for example. Even in this P4, P
2 (a) to (i)
The body W is rotated in the horizontal direction as shown in FIG.

-'' Due to the horizontal rotation of the body W at P3 and P4, the paint dries without sagging even when the paint is sprayed to a thickness of - at P2, the sag limit point. As a result, a high-quality coated surface with extremely high smoothness that could not be obtained with conventional coating methods can be obtained.

What is the third figure of lacquer and sauce?
This shows the influence of coating film thickness on the sag limit. In this Figure 3, the coating film thickness is 40 μm, 53 μm.
Three cases are shown: μm and 65 μm. 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. In addition, the sagging limit is usually 1 to 2 m per minute.
This is the value when sagging of m occurs (visually 2 mm/
The coated surface is considered to be defective if it sag for more than 1 minute), and the maximum coating thickness that can be obtained within the range below this sag limit is about 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 the state in which the body W is not rotated (conventional painting method), and Fig. 4 B shows the case in which the body W is rotated 906 times and then reversed (
Figure 2 (forward and reverse rotation between (a) and (c)). Figure 4C
shows the case where the body W is rotated +35° and then reversed (forward and reverse rotation between Figure 2 (a) and (d))
. The fourth diagram shows the case where the body W is rotated 180 degrees and then reversed (forward and reverse rotation between FIGS. 2(a) and (e)). Fig. 4E shows the case where the body W is continuously rotated in the same direction (Fig. 2(a), (b)
, (c)... Take the posture in the order of (i), and then move 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 (see Fig. 4). 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 coating film is 65μm, the body W is 36mm.
When rotated by 0°, the obtained smoothness is equal to the image sharpness of 1. r87J in G (lower limit of 1.0 in PGD value)
It is. Moreover, when the thickness of the coating film is 40 μm,
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 degrees, it is 1. r68J in G (PG
The lower limit of D value is 0.8).

As is known, IG (Image Cross) in mapping sharpness indicates the ratio of sharpness to a mirror 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 Alkit (black) Viscosity: 22 seconds/20°C with Ford cup #4 b, Coating machine: Mini Hell (16, OOOrpm) Shaping air 1.2, Ok g/cm2 C9 discharge rate = Spraying in two parts, the first time...
] QQcc/min 2nd time, 150-200cc/min, Setting time: 10 minutes x room temperature e, Baking conditions: 140°C x 25 minutes [, Base smoothness: 0.6 (PGD Value) (Intermediate coating, on PE tape) g9 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, rotatable at the center Support 1, rotation speed of the object to be coated: 6 rpm, 30 rpm, 60 r
The experiment was carried out at three different pm values, but virtually no difference occurred due to the difference in rotational speed.

(Margin below) H series This is a trolley with a function to rotate the body W.

In FIG. 5, a base 21 of a trolley is run on a road surface (rails 23) using wheels 22. This base 2
1, a pair of front and rear stays 24 are extended downward and protrude, and a traction wire 25 is fixed to each stay 24. This wire 25 is driven by a motor (path shown) provided at a safe location from an explosion-proof point of view, and the bogie is thereby driven to travel via the wire 25.

On the other hand, a pair of boxes 26 and 27 are fixed on the base 21 at its front and rear ends (left and right ends in FIG. 5). This pair of boxes 26 and 27 is a rotating jig 1 which will be described later.
The box 26, 27 serves as a support portion that rotatably supports the body W via the box 26, 27. For this purpose, bearings 28, 29 are fixedly arranged on the upper surface of each box 26, 27, respectively. The space between the pair of boxes 26 and 27 is a support space (rotation space) 30 that is slightly larger than the longitudinal length of the body W. Note that the rotational drive portion will be described later.

Eclipse Lid 1 As shown in FIGS. 5 and 6, the rotation jig 1 is roughly divided into a front part IF, a rear part IR, and a reinforcing connection part 2 that connects the image part. The front portion IF has the eighth
As shown in the figure, it has a continuous part 3 formed by bending a single iron plate, etc., and a pair of left and right mounting parts 4, and a cylindrical column joined to this continuous part 3 by welding or the like. It has an upper rotating shaft portion 5. The rotating shaft portion 5 is rotatably supported by the box 26 via a bearing 28, and rotation of the rotating shaft portion 5 is transmitted to the mounting portion 4 via the connecting portion 3.

In the embodiment, the attachment portion 4 is detachably attached to the front end portions of a pair of left and right front side frames 11 of the body W using, for example, bolts.

The rear portion IR of the rotation jig 1 is also constructed in substantially the same manner as the front portion IF, so corresponding components will be designated by the same reference numerals and their description will be omitted. however,
The mounting portion 4 of the rear portion IR has a shape that can be inserted into the rear end opening of the rear side frame 12 of the body W without rattling. Of course, the rotating shaft portion 5 of the rear portion 1R is rotatably supported by the box 27 via a bearing 29. Both the front and rear rotating shaft parts 5 are arranged to extend horizontally on the same straight line in the front and back direction with the body W in between, and the axis of the rotating shaft part 5 is the rotation center β. This is the result.

The reinforcing connecting portion 2 of the rotating jig 1 is joined to each of the connecting portions 3 of the front portion IF and the rear portion IR by welding or the like. In the embodiment, this reinforcing connecting portion 2 is formed by using two hollow square iron members on the left and right sides. The joining position for the reinforcing connection portion 2 is set as close to the attachment portion 4 as possible.

On such a reinforcing connection part 2, a side frame 11,
] 2 is at least partially seated so that the weight of the body W is shared and supported by areas other than the mounting portion 4. In addition, the reinforcing connecting part 2 is fixed to the front side frame 11 and the rear side frame 12 by bolts or the like using a bracket 6 at a position apart from the mounting part 4, so that the body W can rotate more reliably without rattling. It is connected to the jig 1 for use.

In the balancing process P1, the rotation center β of the body W
is adjusted so that it passes through the composite center of gravity G (see FIG. 5) of the body W and the rotating jig I in a virtual state approximated to the state where the paint is applied. That is, by matching β and G, rotational fluctuations can be prevented. In order to make adjustments to match β and G, a balance weight, which will be described later, is provided on the rotation axis system of the body W including the rotation jig 1.

Here, in order to create a virtual state in which the paint is actually applied,
In step Pl, as shown in FIG. 42, a plurality of magnet sheets M are used, and FIG. 42 shows seven magnet sheets M. That is, the body W is divided into a plurality of regions such as a hood, a front fender, a front door, a rear door, a rear fender, a trunk lid, and a roof panel.
A magnet sheet M having the same weight as the paint to be applied to each area is pasted. Of course, although not shown, the magnet sheet M is similarly attached to a portion of the body W that is located on the back side of the paper compared to that shown in FIG. 42. In this case, it is preferable for the magnet sheet M to be positioned as widely as possible in each of the above regions in order to approximate the actual state of paint application.

As shown in Figure 42, in a virtual state that approximates the state in which paint is applied, adjustment is made using the following balance weight so that the axis of rotation and the center of gravity G coincide. An example is shown in FIG. 8 with reference numeral B. 41 in FIG. 8 is the first threaded rod,
It is installed between a pair of left and right mounting portions 4 in the front portion 1F of the rotation jig 1. A first weight 42 is screwed onto the first threaded rod 41, and one end of a second threaded rod 43 is fixed to the first weight 42. This second threaded rod 43 extends in a direction perpendicular to the first threaded rod 41,
A second weight 44 is screwed onto the cylinder 2 threaded rod 43. Note that 45 and 46 in FIG. 8 are lock nuts.

Therefore, by changing the screwing position of the first weight 42 to the first threaded rod 4], the magnet sheet M
The final center of gravity G'' of the rotating shaft system including the body W, rotating jig l, and balance weight B is adjusted in the vehicle width direction.
By adjusting the screwing position of the center of gravity G', the vertical position of the center of gravity G' can be adjusted. Furthermore, by adjusting the circumferential position of the first weight 42 with respect to the first threaded rod 41, it is possible to adjust the position not only in the front-back direction but also in the downward and upward positions of the center of gravity G' by the second weight 44. (The height position of the first weight 42 is adjusted in advance so that the center of gravity G passes near the height of the first weight 42). In this way, the position of the center of gravity G' of the rotating shaft system is adjusted so that the center of gravity G' coincides with the center of rotation β.

9 Yen-1 Each of the boxes 26 and 27 contains a drive unit 1, which will be described later. 2 is placed in. This drive unit includes at least a spring as a drive source, and an output shaft 31 to which power from the drive source is transmitted extends outside the box 26 or 27. Each output shaft 31 is transmitted to the front and rear rotating shaft portions 5 via a transmission mechanism 32 consisting of a sprocket and a chain.

The rotational drive unit K1. 2 will be explained below, in which one drive unit Kl is used for startup, and the other drive unit 2 is used for continuous rotation.

2 in the drive unit, as shown in FIGS. 9 and 10,
It has one stock drum 62 and four winding drums 63, each of which is rotatably supported by a casing 6.

The winding drums 63 have a smaller diameter than the stock drums 62 and are arranged at intervals of 90 degrees in the circumferential direction. Each drum 62, 63 has three drum sections 62a or 63a each separated by flanges in its axial direction. Between each drum portion 62a of the stock drum 62a and each drum portion 63a of each winding drum 63, a long thin spring 64 is wound.

That is, one end 6a of the spring 64 is connected to the drum portion 62.
The other end 64b is fixed to the drum part 63a. A total of four springs 64 extending from the four winding drums 63 are wound four times around the stock drum 63.

The spring 64 is attached to the drum portion 63a of the winding drum 63.
) is in a free state,
Therefore, when the spring 64 is wound around the drum 62, the resultant spring force is applied to the spring 64, that is, the spring 64 generates a restoring force. More specifically, when the spring 64 is wound around the winding drum 62, the restoring force generates a restoring force such that the spring 64 is wound around the winding drum 63, and based on this restoring force, the spring 64 is wound around the winding drum 62. The stock drum 62 is rotationally driven (the stock drum 62 is
Also serves as a rotational extraction mechanism that extracts the restoring force of the spring 64 as rotational force). In the embodiment, the spring 64 is of a constant load type, that is, it always generates a restoring force of constant torque, and as a result, if the load on the drum 62 is constant, the drum 62, that is, its rotation axis 62b is rotated at a constant speed.

■Ji machine 1 - “The rotation of the rotating shaft 62b in the distribution card drum 62 is
It is transmitted to the output shaft 31 via the speed increasing mechanism shown in FIGS. 11 and 12. This speed increasing mechanism includes a casing 66 that is disposed close to the casing 61 and also constitutes a part of the box 27.
In addition to the output shaft 31, an input shaft 67 and an intermediate shaft 68 are rotatably supported. The input shaft 67 receives the rotational force from the rotating shaft 62b of the storage drum 62. The rotation of the input shaft 67 is controlled by the speed increasing gears 69A and 6.
The rotation of the intermediate shaft 68 is transmitted to the output shaft 31 via the speed increasing gears 70A and 70B.

A brake drum 56 is integrated with the output shaft 31, and a shoe 58 biased by a spring 57 is in contact with the brake drum 56. 56 of these elements
．． A constant load mechanism M consisting of 57 and 58 applies a constant load corresponding to the biasing force of the spring 57, and the rotation of the output shaft 31 based on the restoring force of the spring 64 as the rotational drive source becomes even more constant rotation. This is how it should be.

Ratchet N Further, a ratchet gear 71 is fixed to the output shaft 31 outside the casing 66 (box 26),
A ratchet pawl 72 is adapted to be engaged with and disengaged from this ratchet gear 71 (see also FIG. 13). The ratchet pawl 72 is swingably supported by the casing 66 around a pin 73, and is engaged with and disengaged from the ratchet gear 71 by operating a lever 74 connected thereto. In such a ratchet mechanism N, the rotation direction of the ratchet gear 71 (output shaft 31) in the clockwise direction in FIG.
When the ratchet pawl 72 is engaged with the ratchet gear 71, the output shaft 31 is prevented from rotating due to the restoring force of the spring 64. In other words, by manually operating the lever 74, for example, rotation using the restoring force of the spring 64 as a rotational drive source and rotation prevention (stopping the extraction of the restoring force) can be performed as desired.

In addition, in FIG. 12, 32a is a sprocket fixed to the output shaft 31 and constitutes a part of the transmission mechanism 32, and 33 is an engagement part (rewinding external force input part) for rewinding a spring 64, which will be described later.

■Ratchet mechanism O To automatically switch the operation of the ratchet mechanism N described above when the trolley ■) comes to a predetermined position, this can be done, for example, as follows, and this point can be explained with reference to FIG. I will explain. In addition, in the one shown in FIG. 14, the ratchet mechanism N is arranged in the box 27.

First, a guide bar 75 is fixedly arranged along the travel trajectory of the truck. The surface of the guide bar 75 facing the carriage is composed of a low portion 75a, a high portion 75b, and a tapered surface 75C that smoothly connects the image portion.

On the other hand, a bell crank 77 is swingably supported by a bracket 76 fixed to the box 27, and the proximal end of the manual rod 8 is connected to one end of the bell crank 77. An output rod 79 connected to the lever 74 is connected to the portion. The input lot 78 is held by the bracket 76 so as to be slidable in a direction perpendicular to the conveying direction of the trolley, and a roller 80 as a follower is rotatably attached to the tip end of the input lot 78. The roller 80 is urged by the spring 81 so that it always comes into contact with the guide bar 75.

With the configuration described above, the position of the lever 74 is changed depending on the height position of the guide bar 75 that the roller 80 comes into contact with, and in the embodiment, when the lever 74 comes into contact with the high part 75b, the ratchet mechanism N Rotation of the output shaft 31 is prevented, and conversely, when the roller 80 comes into contact with the low portion 75a, the rotation of the output shaft 31 is allowed.

(The following is a blank space) Drive unit Kl (starting m) The drive unit K1 provided in the box 26 will be described with reference to FIGS. 15 and 16. Note that the same components as those in drive unit K2 are designated by the same reference numerals and their explanations will be omitted.

First, the configurations of the spring 64 as a rotational drive source, the storage drum 62, and the winding drum 63 are the same as those of the drive unit for continuous rotation (K2) described above, but each drum 62, 63 and spring 64 are different from each other. The drive unit differs from the second drive unit in that only one drive unit is provided. Further, rotational force is applied to the rotating jig 1 based on the restoring force of the spring 64 via a reduction gear and a clutch.

First, a clutch plate 85a and a clutch drum 85b of a friction type clutch 85 are rotatably supported in the box 26, and a gear 86 fixed to the outer periphery of the clutch clutch 85 is fixed to the rotating shaft 62b of the clutch drum 62. It is meshed with gear 87. The gears 86 and 87 constitute a speed reduction mechanism, and therefore the gear 86 has a larger diameter than the gear 87.

The clutch output shaft disposed within the clutch drum 85b is the output shaft 31. Therefore, clutch 85
When connected, the rotation of the storage drum 62 (rotating shaft 62b) based on the restoring force of the spring 64 is decelerated and transmitted to the output shaft 31. This ensures the large torque required at startup.

The clutch 85 is provided to quickly disconnect the starting spring 64 from the rotating jig l after the body W starts rotating. In other words, since the restoring force of the spring 64 for starting is decelerated and transmitted to the output shaft 31, it is set so that the restoring force is lost when the body W is rotated approximately once (the winding drum 63
). On the other hand, even if the spring 64 for continuous rotation has the same length as the spring 64 for starting, since it rotates the body W via the speed increasing mechanism,
This means that the body W can be rotated at a higher number of rotations (for example, 10 rotations) than the starting spring 64. After starting, the clutch 85 is disengaged so that the starting spring 64 does not inhibit the rotation of the body W.

In order to automatically engage and engage this clutch 85, in the embodiment, the amount of winding of the spring 64 around the stock drum 62 (
The radial size of the drum 62 including the spring 64 is detected, and the clutch 85 is disengaged when the amount of winding becomes almost zero.

A mechanism Q for detecting the amount of winding of the spring 64 around the storage drum 62 is shown in FIG. That is, a lever 89 is swingably supported with respect to the box 26 around a bin 88, and a sphere 90 as a follower is rotatably held at the tip of the lever 89. The lever 89 is moved by a spring 91 to the outer peripheral surface of the stock drum 62 (the wound spring 64).
It is biased so that it is always in contact with. A cable 92 is connected to this lever 89. That is, the cable 92 has at least both ends connected to the box 2.
6, and an inner wire 92b disposed inside the outer tube 92a,
2b(7) - The end is connected to the lever 89. The other end of the inner wire 92b is connected to a clutch release lever 850 of the clutch 85, as shown in Figure $15.

As a result, when the amount of winding of the spring 64 around the drum 64 decreases and the restoring force of the spring 64 becomes almost zero, the release lever 85c is displaced by the displacement of the lever 89 via the inner wire 92b.
Clutch 85 is disengaged.

Modified Example of Starting Spring FIG. 17 shows a modified example of the starting spring, in which a spiral spring 64-1 is used as the spring. This mainspring spring 64-1 has one end 64
-1a is fixed to the storage drum 62, and an engaging protrusion 95 is fixed to the other end (free end) 64-1b. Further, a cam piece 96 fixed to the output shaft 31 is arranged near the engagement protrusion 95. When the mainspring spring 64-1 is wound around the drum 62, the merging protrusion 95
17 in the counterclockwise direction, and when receiving this restoring force, the cam piece 96 moves the merging protrusion piece 95.
is pressed, and the output shaft 31 (body W) is rotated.

Conversely, when the engaging protrusion 95 is rotated clockwise in FIG. 17, it is virtually impossible for the merging protrusion 95 to press the cam piece 96.

The winding of the mainspring spring 64 - 1 and the winding of the output drum 62 are performed via a ratchet gear 97 . This ratchet gear 97 is interlocked with the stock drum 62 via a gear 98 that meshes with it. Then, the ratchet gear 97 and the ratchet pawl 99 are engaged. This ratchet pawl 99 is swingable about the pin 100, and allows the ratchet gear 97 to rotate clockwise in FIG. 17, but prevents it from rotating in the opposite direction.

Therefore, a stopper pin (not shown) is inserted into the stopper hole 96a formed in the cam piece 96, and the stopper pin is inserted into the box 26.
While the ratchet gear 97 is locked in the first
Figure 7 When clockwise rotation is applied, the mainspring spring 64-1
is wound around the drum 62 (at the rotation of the ratchet gear 97 @ 97a, the engaging portion 33 serves as an input portion for the external force for winding).
After that, if the locking by the stopper pin is released, the output shaft 31 will rotate using the restoring force of the mainspring spring 64-1 wound around the drum 62. At this time, the ratchet gear 9
7 is idled.

FIG. 18 shows yet another modification of the starting spring, in which the same elements as those shown in FIG. 17 are given the same reference numerals. In this embodiment, a leaf spring 64-2 is used as the starting spring. That is, the leaf spring 64
- One end of 2 is fixed to the box 26, and the other end (free end)
In the case of this embodiment, in which the leaf spring 64-2 faces the cam piece 96 so as to be able to come into and out of the cam piece 96, the restoring force is accumulated when the leaf spring 64-2 is shown by the solid line in FIG. The restoring force is released to the state shown by the broken line.
The resultant force of the restoring force on the box 26 is applied by sliding the pin 102 along the lesson 101 from the outside via a pin 102 fitted into a long hole 101 formed in the box 26.

Fixed posture stopper m4tR This is a mechanism for stopping the body W in a predetermined rotational posture.

As shown in FIG. 19, the fixed position stopper mechanism R includes a stopper rod lO5 slidably inserted into the box 27.
It is equipped with As shown in FIG. 20, this stopper rod 105 has a pair of rods 105a and 105b slidably fitted together at their base ends, and both 105a and 105b are attached in the direction of extension by a spring 105C. It has become a growing trend. And each rod 105
A three-way sphere 106a or 106b serving as a follower is rotatably held at the tip of each of the tips a and 105b.

One end of such a stopper rod 105 (-end sphere 1
06a) faces the outer periphery of the winding drum 63, and the other end (other end sphere 106b) faces the side surface of the rotating shaft portion 5 of the rotating jig 1. A locking recess 107 is formed in the outer peripheral surface of the rotating shaft portion 5.

With the above configuration, as the rotation of the body W progresses, the amount of winding of the spring 64 wound around the winding drum 63 increases, and the amount of winding of the spring 64 around the winding drum 63 increases, and the amount of winding of the spring 64 around the winding drum 63 increases.
is approached to the rotating shaft portion 5, and the winding drum 6
When the amount of winding of the spring 64 with respect to 3 reaches a predetermined amount,
)-/The sphere 106b of the parrod 105 is in the locking recess 10.
7, the winding of the spring 64 by the winding drum 63 is restricted, that is, the rotation of the rotation jig 1 (body W) is stopped. When the sphere 106b is fitted into this locking recess 107, the body W assumes a predetermined posture, and in the embodiment, as this predetermined posture, the body W assumes the state shown in FIGS. 5 and 7. It is set as follows.

Modification of fixed-position stopper mechanism H In FIGS. 21 and 22, the fixed-position stopper bin R includes a mechanical counter 108 fixed on a box 26 or 27. This counter 108 counts by moving its counter 108a up and down, and for this purpose, the rotating jig 1
A projecting piece 109 for operating the counter par 108a is provided on the side surface of the rotating shaft portion 5. On the other hand, the counter 108
A locking lever 110 is swingably supported around a pin 111. When the counter 108 counts a predetermined number of times, its actuating piece 1O8b is projected upward in the figure and locks /<-110 to swing counterclockwise in FIG. 21. When the locking lever 110 swings counterclockwise, the locking recess 11 locked on the outer peripheral surface of the rotating shaft portion 5
The locking lever 111 is fitted into the shaft 2, and the rotation of the rotating shaft portion 5 (body W) is stopped.

Unloading the body W from the trolley in transfer device process 5 or process P
This is a device for loading the body W onto the trolley at step 7. Examples are shown in FIGS. 23 to 25,
The description will focus on the one for process P5. As shown in FIG. 25, this transfer device has a truck movement trajectory R1 in the painting line and a movement trajectory R1 of the cart or hanger, etc. in the assembly process.
2 is installed at the adjacent transfer station Sl.

The transfer device installed at this transfer station S1 is substantially composed of a lifter 51, as shown in FIGS. 23 and 24. 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 driven up and down, and from each base 53,
Support legs 54 are each driven to extend and contract.

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 body W from the painting line
When the bogie supporting the 0-bogie is stopped at the transfer station Sl, the support leg 54 is extended from the base 53 at the lowest position, and then the base 53 is moved upward. .

As a result, as shown in FIGS. 23 and 24, the body W on the truck is lifted from the truck while the side sill or floor frame portion of the body W is supported by the support portions 54a of the support legs 54. be elevated to a higher position. Thereafter, the assembly line trolley is placed at the transfer station Sl. After this, the base 53 is lowered and the body W is transferred to a trolley for the assembly line. Then, in preparation for the next transfer, the support legs 54 are retracted (23rd
(See figure--dotted chain line). In this way, the body W is transferred from the painting line truck to the assembly line truck.

On the other hand, the mounting of the body W on the trolley at P7 may be carried out in the reverse order to the above procedure, and the body W mounted on the trolley at this time is, of course, unpainted.

3′? In addition, 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 that clamps the dolly from the front, back, left and right directions. Assuming that the device has a hanger that is intermittently fed to a high place, the body W is transferred to the hanger at one end using the lifter 51, and then the body W is moved to the upper part of the assembly line trolley using the hanger, and the lifter is again moved at this position. It may also be used to transfer the body from the hanger to an assembly line trolley.

Rewinding mechanism T This is for storing force (storing restoring force) in the rotation springs 64 (64-1, 64-2). , is provided on the conveyance path of the truck immediately before the unpainted body W is placed on the truck.

As shown in FIG. 26, the rewinding mechanism T includes a pair of left and right guide posts 121 and a slider 122 fitted to each guide post 121 so as to be vertically movable. The sliders 122 are connected to the wires 1 by motors 123, respectively.
It is moved up and down via 24. A pair of left and right sliders 122
A holding bar 125 is installed between the holding bar 1
A casing 126 is fixed to the intermediate portion of 25.

Inside this casing 126, as shown in FIG.
An air motor 27 and a speed reducer 128 are provided, so that the rotation of the motor 127 is reduced by the speed reducer 128.

Then, the output shaft 128a of the reducer 128 is connected to the casing 1.
26, and a retaining box 1 is attached to the tip thereof.
29 is fixed.

With the above configuration, when the truck approaches, the casing 126 is lowered, and as the truck approaches further, the unwinding retainer provided on the truck is connected to the engagement box 129. The portion 33 is engaged. After this, the motor 127 is driven to rotationally drive the retaining part 33,
The force is stored in the rotation spring 64.

After accumulating this force, the cart is once moved slightly backward with respect to the unwinding mechanism z, and then the casing 126 is moved upward. After this, move the cart to the left and right guide posts 12.
1 and then moved to the next step P7.

The rewinding mechanism T may be implemented by separately providing a dedicated actuator or by utilizing the displacement of the trolley relative to the rail 23. In this case, for example, a rack bar is fixedly arranged for a predetermined length along the running trajectory of the truck, and a gear that meshes with the rack bar is rotatably supported on the truck, and as the gear rotates. The spring 64 may be unwound (for example, by connecting the gear and the slaughter drum 62 using a wire and a drum around which the wire is wound). Of course, the rack bar is provided with a length corresponding to the number of rotations of the gear necessary for storing force in the spring. In such a case, the rack bar should be placed at multiple locations along the moving trajectory of the trolley, for example, at processes Pi, P3, and P.
4, the length of the spring 64 used in the embodiments shown in FIGS. 9 and 10, for example, can be shortened.

Modified examples of rotating jig In the above embodiments, the rotating jig l is placed on a trolley,
The body W is attached to the rotating jig l attached to this trolley.
Although we have explained the case where the rotation jig 1 is attached to and detached from the body W, it is also possible to attach the rotation jig 1 to the body W in advance and then attach the set of the body W and the rotation jig 1 to a trolley. For this purpose, for example, the rotating shaft portion 5 of the rotating jig 1 may be made to be able to be engaged with and disengaged from (the supporting portion of) the cart D from above in FIG.

Examples for this purpose are shown in FIGS. 28 to 33. In these figures, the rotational drive is transmitted only from the front rotating shaft 5, and the rear rotating shaft 5 is always transmitted. It is of a type that rotates as the body W rotates. In order to engage and disengage the transmission mechanism 32 from the front rotating shaft portion 5, a connecting shaft 40 that is always rotatably connected to the transmission mechanism 32 (for example, spline engagement) is slidably connected to the transmission mechanism 32 on the box 26. It is intended to be held in place.

Based on the above, a notch 26a is formed on the box 26 (see FIGS. 20 to 30), and a notch 26a is formed on the box 27 (see FIGS. 20 to 30). 27a is formed (Fig. 28, 3
2 and 33), both of the notches 26a and 27a are sized so that the rotating shaft portion 5 can fit therein. A flange portion 5a is formed on the rear rotating shaft portion 5, and a notch 27b having a shape corresponding to the flange portion 5a that communicates with the notch 27a is formed in the box 27. As a result, the rear rotating shaft portion 5 is connected to the box 27.
It is engaged and disengaged from the vertical direction with respect to the notches 27a and 27b, and is made immovable in the axial direction with respect to the box 27 by the stopper action of the flange portion 5a.

The connecting shaft 40 is engaged with and disengaged from the rotating shaft portion 5 on the front side. That is, as shown in FIGS. 28 to 30, a cross-shaped connecting portion 5b is formed at the tip of the rotating shaft portion 5, while a cross-shaped connecting portion 5b is formed at the end 4+ of the connecting shaft 40. As shown in FIG.
A box portion 40a is formed which has an engagement recess 40c into which the box portion 40c is fitted without rattling. Thus, the rod 43 can be removed, for example by means of a pneumatic cylinder 42 or manually.
By sliding the connecting shaft 40 through the box part 40a (engaging recess 40C) and the connecting part 5b are engaged and disengaged, and at the time of engagement, the connecting shaft 40 and the front rotating shaft part 5 are connected to each other. It is possible to rotate as one unit. Note that, as shown in FIG. 28, the rod 43 is inserted into an annular groove 4O formed on the outer periphery of the box portion 40a so as not to inhibit the rotation of the connecting shaft 40.
It is fitted into b.

With the above configuration, by lowering the body W, in which the rotation jig 1 is set in advance, with respect to the trolley while the connecting shaft 40 is displaced to the right side in FIG. The shaft portion 5 is supported by the boxes 26, 27 in a rotatable and immovable manner in the longitudinal direction. After that, the connecting shaft 40 (locking recess 40c) is engaged with (the connecting portion 5b of) the front rotating shaft portion 5 (the body W is rotated 4F).
) G Possible). In addition, the removal of the truck frame of the body W may be performed in the reverse order to the above-described procedure.

Uni, -) K2 l/$34 Figure shows another example of 2 in the drive unit. In the case shown in Fig. 34, the spring 64-3
A spiral spring is used as the speed control mechanism 2, and a speed regulating mechanism 2 is used. The spring 64-3 has one end fixed to the box 27 and the other end fixed to the rotating shaft 140. The rotation of the rotating shaft 140 is transmitted to the output @31 via the gear 141, the shaft 142, the shaft 143, the gear 144, the gear 145, the shaft 146, the cam clutch 15o, the sprocket 147, the chain 148, and the sprocket 149.

The cam clutch 150 transmits only the rotation of the shaft 146 in the direction of the arrow in the figure, which corresponds to the rotational direction based on the restoring force of the spring 643, to the sprocket 147.

Further, the shaft 146 is provided with a constant load mechanism M similar to that shown in FIG.

The speed regulating mechanism Z includes a type gear 151, a feed gear 152, and a pendulum 153. As shown in FIGS. 35 and 36, the mold gear 151 is fixed to one end of the shaft 14B, and as shown in FIGS. It has f. The feed pawl 152 acts on the mold gear 151, and has two left and right pawl portions 1.
52a and 152b, and is swingable around a shaft 154. The pendulum 153 includes an arm 153a whose upper end is fixed to the swing center of the feed claw 152, and an arm 15
It has a weight 153b attached to the lower end of 3a. Such a speed regulating mechanism Z is based on the swing period of the feed pawl 152 determined by the pendulum 153 and the spring 64-3.
This shows the effect of rotating the shaft 146 at a constant speed by applying a rotational force in a predetermined direction (clockwise in FIGS. 37 to 40) from the position shown in FIG. The operating order is as shown in Fig. 37 -> Fig. 38 -> Fig. 39 - Fig. 40, and after Fig. 40, the state returns to the state shown in Fig. 37 (however, the mold gear 151 has only one pawl). (The angle is advanced by an amount corresponding to

FIG. 41 shows still another modification of the drive unit (K2), in which the same components as those shown in FIG. 34 are given the same reference numerals. In the one shown in FIG. 41, a coiled torsion spring 64-4 wound around the shaft 140 is used as the spring. Of course, the spring 64-4 has one end fixed to the box 27 and the other end fixed to the shaft 140. and,
The rotation of the shaft 140 is controlled by the sprocket 155 and the chain 15.
6. After passing through the sprocket 157, the shaft 158, and the gear 159, it is transmitted to the rotating jig 1 (rotating shaft portion 5 thereof) in the same manner as after the gear 144 in FIG. In addition,
The reason why the chain 156 is used in this way is that the torsion spring 64-4 is long, so the spring 64-4 is placed in a low position such as the base 21 of the trolley.
This is because -4 is arranged.

(The following is a blank space) Supplementary Work j4 Although the embodiments have been described above, the present invention is not limited to this, and includes, for example, the following cases.

(2) As a spring serving as a rotational drive source, a gas spring in which a piston rod is enclosed in a cylinder filled with gas at a predetermined pressure can also be used. In this case, the restoring force of the gas spring appears as a linear motion of the piston rod, so the linear motion may be converted into rotational motion using, for example, a rack and pinion.

(2) The spring serving as the rotational drive source may be one that does not differentiate between the spring for starting and the spring for continuous rotation. Alternatively, it may be provided only on either the front or the rear (the rotational force is applied only from one side of the front or rear of the body W).

If there is no distinction between starting and continuous rotation, the restoring force of the spring may be transmitted to the body W via the transmission. That is, the transmission may be used to decelerate the engine at startup, and the transmission may be used to increase the speed after startup.

In this case, the transmission may be switched using a mechanism as shown in FIG. 14, for example.

(2) When using a starting spring, a one-way clutch may be used instead of the friction clutch 85 shown in FIG.

(2) The object to be coated may be any object other than the automobile body W.

(2) The object to be coated may be rotated at a constant speed using the Ten 1 mechanism.

■For rotational drive, other than springs may be used, such as using an air dryer, or using a rack-and-binion mechanism to extract the displacement of the trolley relative to the road surface as rotation. Can be adopted.

(Effects of the Invention) As is clear from the above description, the present invention can provide a coated surface with even better smoothness if the thickness of the coating film is the same.

In addition, in order to balance the weight of the paint applied to the object and ensure that the rotation of the object is optimal, the object must be rotated smoothly with as little force as possible. This is also preferable in terms of preventing the paint from sagging due to this rotation.

Furthermore, since the above-mentioned balancing for optimally setting the rotation is done before the painting process, there is no need to consider the time it takes for paint to sag, and this balancing work can be done with sufficient time. can.

[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 and sag, paint surface smoothness, and rotation. FIG. 5 is a side view showing an example of a body transporting trolley and a rotating jig which are adapted to rotate the body. FIG. 6 is a plan view of FIG. 5 showing the cart and the rotating jig. Figure 7 is a left side view of Figure 5. FIG. 8 is a perspective view showing the front part of the rotation jig. FIG. 9 is a front view of main parts showing an example of installing a spring for continuous rotation. FIG. 10 is a partially sectional plan view of FIG. 9 when viewed from above. FIG. 1I is a simplified front view of the speed increasing gear mechanism viewed from the axial direction. FIG. 12 is a partial plan view taken along line XX in FIG. 11. FIG. 13 is a side view of a main part showing a ratchet mechanism that performs rotation by a rotation spring and rotation stop. FIG. 14 is a plan view of essential parts showing an example for automatically operating the ratchet mechanism shown in FIG. 13. FIG. 15 is a plan sectional view showing the installation part of the starting spring. FIG. 16 is a sectional view taken along the Y-Y line in FIG. 15. FIGS. 17 and 18 are partial cross-sectional views showing other installation examples of starting springs. FIG. 19 is a partially sectional front view showing an example of a stopper mechanism for locking the object to be coated in a predetermined rotational posture. FIG. 20 is a sectional view of the stopper rod used in FIG. 19. 21 and 22 show another example of a stopper mechanism for locking the object to be coated in a predetermined rotational posture, with FIG. 21 being a front view and FIG. 22 being a perspective view. Figures 23 to 25 show an example of a device for transferring objects to be coated onto a trolley. Figure 23 is a front view, Figure 24 is a side view, and Figure 25 is a simplified diagram showing the movement trajectory of the trolley. FIG. 26 and 27 show a force storage device for applying restoring force to the rotation spring, with FIG. 26 being a perspective view and FIG. 27 being a side view. FIG. 28 is a side sectional view showing the other side of the joint portion between the rotating jig and the table. FIG. 29 is a sectional view taken along the line X1l-Xll in FIG. 28. FIG. 30 is a plan view of FIG. 29. FIG. 31 is a sectional view taken along line XI3-Xla in FIG. 28 (7). FIG. 32 is a sectional view taken along the line XI4-XI4 in FIG. 28. FIG. 33 is a plan view of FIG. 32. FIG. 34 is a mechanical diagram showing a modification of the drive unit. FIG. 35 is a front view showing an example of a speed regulating mechanism. FIG. 36 is a right side view of FIG. 35. 37 to 40 are front views showing the operation of the speed regulating mechanism. FIG. 41 is a mechanical diagram showing still another modification of the drive unit. FIG. 42 is a side view showing an example of obtaining a virtual state that approximates the state in which paint is actually applied for balance. P1 to P4: Process W: Automobile body (object to be coated) β: Rotation axis D = Transport platform 11 (B: Balance weight M: Magnet sheet (for balancing) K1. to 2: Drive unit l: Rotation fixture Tool 31: Rotation output shaft

Claims (1)

[Claims] (1) A coating method comprising a coating process of applying paint to an object by spraying, and a drying process of drying the applied paint, in which the paint applied to the object is sprayed. The thickness is greater than the sag limit, and in the drying step, the coating material is rotated around a predetermined axis of rotation extending approximately horizontally until the paint applied to the object is cured to the point where it no longer sag. Before the painting step, the object to be coated is balanced so that the center of gravity of the rotating system is located on the predetermined rotation axis line, taking into account the weight of the paint to be applied in the painting step. A painting method characterized by: