KR940006975B1 - Method and apparatus for painting - Google Patents

Abstract

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Description

Coating method and painting device

1 is a plan view showing the overall configuration of the coating device showing an embodiment of the present invention.

Figure 2 is a ping surface showing the overall configuration of the coating apparatus showing another embodiment of the present invention.

3 is a plan view showing the overall configuration of the coating device showing another embodiment of the present invention.

4 is a time chart showing the state of drying of the coating, taking 140 ° C x 20 minutes curing type diagram as an example.

5 is a time chart showing a state in which the paint is dried, taking a 150 ° C. × 20 min curable paint as an example.

* Explanation of symbols for main parts of the drawings

MB: Main drying furnace MBL: Drying line (supply line)

W: Object to be coated D: Carrier (General Carrier)

D2: Carrier (rotary transport vehicle)

CL1-CL3, CL11-CL14, CL21-CL24: Coating Line

SP1-SP3, SP11-SP14, SP21-SP24: Painting Area

ST1-ST3, ST11-ST14, ST21-ST24: setting area

PB1-BP3, PB11-PB14, PB21-P24: Preliminary Drying Furnace (Preliminary Drying Zone)

KL1-K12, KL11-KL12, K121-K122: Common Line

J1-J2, J11-J12, J21-J22: Carrying Device

X1-X4, X11-X12, X21-X22: Branch

Y1-Y4, Y11-Y13, Y21-Y22: confluence

The present invention relates to a coating method and a painting apparatus. In a painting line for painting a to-be-painted object, for example, a painting line for painting a car body, a series of facilities are installed from the application of the paint to the finished material until the drying of the applied paint is completed. do.

In other words, the coating zone to apply the paint to one coating line and the setting zone to keep the applied paint at a low temperature such as room temperature to evaporate the volatiles in the coating zone and the drying furnace to heat-dry the coated material after passing through the setting zone. Is installed. In the drying furnace which heat-drys, in order to prevent the defect by the sudden volatilization of volatile components in paint, the temperature of a to-be-painted object is gradually performed over a considerable time.

Thereafter, the coated object is held at a temperature of about 140 ° C. for a predetermined time to perform thermal drying.

Japanese Unexamined Patent Publication No. 61-143684 discloses that the temperature in the region where the temperature of the coated object is heated in the drying furnace that performs heat drying, that is, the temperature of the inlet code of the drying furnace is set lower than the temperature of the exit code to prevent sudden temperature rise of the coated object. Is disclosed.

In addition, for example, in Eleven Publication No. 63-248749, there is disclosed a technique of rotating a coated object about an approximately horizontal axis during coating of the paint to obtain a smooth coating surface while preventing the paint from flowing down.

By the way, in recent years, there are many different coating conditions required when painting the to-be-painted object, that is, an automobile body. For example, the difference in the paint itself (e.g. oil paint and water-based paint), the difference in the number of coatings of the paint (e.g. 1 and 2 paints), the difference in the film thickness of the paint, and the difference in color (e.g. one Painting conditions, such as the coloring and the difference between the two paintings), the need for the rotation of the coated object, etc. tend to be extremely diverse.

When the kind of coating conditions required in this way increases, it is difficult to cope with one coating line, and thus, it is necessary to prepare several coating lines. Such necessity of several coating lines is also required in mass production even under the same coating conditions. However, in order to provide a drying furnace for each of these several coating lines, considering that the drying furnace is large and expensive, some countermeasures are required in this regard.

In addition, the installation of an extremely large drying furnace that independently completes the drying of each painting line will place a significant limitation on the overall configuration of the painting apparatus.

Accordingly, an object of the present invention is to presuppose having a plurality of coating lines, to simplify the drying furnace as a whole, and to a coating method and a coating apparatus to increase the degree of freedom of design of the entire coating apparatus.

In order to achieve the above object, the present invention basically has the following configuration. That is, a plurality of coating lines having a coating zone for applying paint to each coated object and a preliminary drying furnace for pre-drying the coating applied in the coating zone and the above-described multiple coating lines are set to be used in common. One main drying furnace is provided, and after the above-mentioned preliminary drying furnace is finished, the to-be-painted objects from several coating lines are supplied to the said drying furnace, and the main drying in the main drying furnace is performed.

In addition, in the apparatus of the present invention, the configuration is basically as follows. That is, the drying area set to pass through the main drying furnace and the several coating lines and the main drying furnace having a coating zone for applying paint to each coated object and a preliminary drying furnace for predrying the coating applied in the coating zone. Each of the paints flowing independently of the lines and the plurality of coating lines, respectively, is provided on the downstream side of the preliminary drying furnace, and is provided with a transfer means from the respective painting lines to the drying line.

In the present invention, since only one main drying furnace for finally drying the paint is sufficient for several coating lines, the entire coating line can be simply configured as compared with the case where a drying furnace is provided for each coating line.

In addition, since the volatilization in the paint is considerably volatilized at the time of passing through the preliminary drying furnace, the main drying furnace can raise the workpiece to a predetermined temperature without considering most or none of the defects. It can shorten itself or reduce installation costs and improve overall productivity.

In the painting line, the paint is pre-dried in advance, so it is also considered that there is a need to move a considerable distance from the painting line to the main drying furnace after leaving the painting line. As a result, it is possible to reliably avoid the possibility of dust or the like adhering to the painted surface before reaching the main drying furnace.

The same problem can be avoided even when moving from one painting line to the next in the same way, even if the painting is carried out in sequence between several painting lines without passing through the main drying furnace in the same way. On the other hand, the coating surface formed in the preceding step is already preliminarily dried during the application of the paint, so that the overlapping can be performed satisfactorily.

As a result of the above-mentioned preliminary drying, problems such as dust adhesion to the coating surface are eliminated, and a large main drying furnace which finally completes the drying is sufficient, so the degree of freedom in how to design several main drying furnaces and coating lines is sufficient. Is also extremely high.

In particular, each coating line is configured independently for the drying line for supplying the workpiece to the main drying furnace, for example, by transferring the workpiece from each coating line to the drying line using a lift type transfer device. The degree of freedom in design is dramatically increased.

Preferred shapes and advantages of the field name will become apparent from the description of the following examples. Below. An embodiment of the present invention will be described based on the accompanying drawings.

In FIG. 1, three coating lines of the 1st coating line CL1, the 2nd coating line C12, and the 3rd coating line CL3 are comprised. One main drying furnace MB is provided for these three coating lines CL1, C12, and CL3. Of the three coating lines CL1 to CL3, the third painting line CL3 is configured as an endless track type using the common line KL.

For this common line KL, the downstream portion of the first coating line CL1 is joined at the joining portion Y1, and the downstream portion of the second coating line C12 is joined at the joining portion Y2. It is becoming. In the common line KL, the branch line KL-A branches from the branched portion X1, and the upstream portion of the second coating line C12 is connected to the branch line KL-A.

In this branching line KL-A, the upstream part of the 1st coating line C12 continues through the branching part X2 again. In addition, the branching lines KL-A are again provided with two branching portions X3 and X4. A line TL1 is connected between the branch portion X3 and the confluence portion Y3 formed in the upstream portion of the first coating line CL1. Moreover, between the branch part X4 and the confluence part Y4 formed in the upstream part of the 2nd coating line C12, it is connected by the line C12.

Each of these lines TL1 and T12 is for temporarily waiting for a to-be-painted object, that is, a transport vehicle for transferring the to-be-painted object. In the first coating line CL1, between the joining portions Y3 and Y1, the preparation zone PR1, the painting zone SP1, and the setting 1 from the upstream side to the downstream side (toward the right side from the left side of the drawing) in order. Zone ST1, a preliminary drying zone, that is, a preliminary drying furnace PB1, is installed.

The coating area SP1 is composed of an undercoat area SP1-A for spraying the undercoat, a flashover idle area SP1-B and a cooler fill area SP1-C for spraying the cooler paint. have. The coating of the paint in the coating area SP1 is performed by electrostatic coating or the like.

The second painting line C12 and the third painting line CL3 are also configured in the same way as the first painting line, and the corresponding components have the sign of "2" or "3" instead of the sign of "1". The duplicate explanation is abbreviate | omitted by showing using. However, the area SP3-B in the third painting line becomes a flashover heating zone, and each setting area ST2 of the third painting line C12 and the third painting line CL3, ( Each of ST3) is fixed at a high temperature to perform so-called preheating.

That is, the setting zone ST1 in the first coating line CL1 is at a low temperature of room temperature, but is lower than the hotbed state in the preliminary precursor zones PB2 and PB3 in ST2 and ST3, and is sufficiently higher than room temperature. It becomes a high temperature state. In addition, the preliminary drying furnaces (PB1)-(PB3) and the main drying furnace (MB) are composed of far-infrared warm air type, so that this side is combined.

In this case, the drying conditions in the main drying furnace MB are common to several coating lines CL1 to CL3. On the other hand, the drying conditions in the preliminary drying furnaces PB1-PB3 are set independently for each coating line CL1-CL3, respectively. However, the paint is cured to a certain degree at the stage of preliminary drying in the preliminary preheating furnaces (PB1)-(PB3).

That is, at the point immediately after passing through the pre-drying furnaces (PB1)-(PB3), the paint (coated surface) is cured to the extent that it will not become dust or the like due to viscosity, and it is painted with an external force that is lightly touched with a finger. It hardens to the extent that it does not affect the cotton at all.

In addition, in order to more securely prevent the adhesion of foreign matter such as dust on the painted surface, the transfer path of the workpiece W from each of the preliminary drying furnaces PB1 to PB3 to the entrance of the main drying furnace MB. Truth is formed. One drying line (MBL) is installed in the main drying furnace (MB).

Between the drying line MBL and the common line KL, the first and second two transfer devices J1 and J2 are in series between the branched portions X1 and Y1. It is installed. The position is lower in the branch portion X1 than in the first stacking device J2.

The first conveying device J1 carries the object to be coated W before painting from the drying line MBL to the common line KL. In addition, the second transfer device (J2) is for transferring the workpiece (W) after passing the preliminary drying zone (PB1), (PB2) or (PB3) from the common line (KL) to the drying line (MBL). will be.

In this way, the drying line MBL serves as a coating material supply line for supplying the coating object W to each of the painting lines CL1 to CL3. In addition, in the embodiment, the object to be transported W is transferred to the transport vehicle D as an automobile body, and finally passes through the main drying furnace MB after a predetermined process as described later. In the drawing, only one to-be-painted object W supported by the transport vehicle D is shown briefly.

In the above-described configuration, the to-be-coated article W, which is a to-be-painted article, is transported on the drying line MBL by the transport vehicle D to reach the first transporting device J1, and the first transporting It is moved to the common line KL by the apparatus J1. The to-be-coated W transferred to the common line KL is classified according to the coating conditions required for each to-be-coated W and supplied to any one of the first to third three lines.

The second to-be-painted object W after passing through each of the first to third coating lines CL1 to CL3 is second-loaded by using the common line KL via the confluence Y1 or Y2. It is conveyed to the apparatus J2, and is transferred to the drying line MBL from the common line KL again by this 2nd conveying apparatus. The drying line MBL and the to-be-coated article W transferred by the second loading device J2 are subjected to main drying, that is, final thermal drying in the main drying furnace MB.

Table 1 shows the coating conditions performed in each coating line CL1-CL3.

Table 1

In Table 1, the coating lines CL1 and C12 are coatings using an oil paint, but the temperature of the setting step ST1 in the first coating line CL1 becomes room temperature (around 20 ° C). On the other hand, the temperature in the setting step ST2 in the second coating line C12 is considerably higher than room temperature because of the preheating. By carrying out this preheating, the finish of the painted surface is improved. In addition, the third coating line CL3 is a coating using an aqueous paint. In this case, Table 1 is intended to sufficiently volatilize the moisture in the paint at a relatively low temperature of about 50 ° C at the beginning of the setting step (ST3). Then, the temperature in the preliminary drying furnace PB3 is set to the same temperature as in the main drying furnace MB.

Such condition setting of the third coating line CL3 corresponds to the coating material of the hardening type for a long time, and also prevents the occurrence of defects and the like by the control of the temperature increase rate. In the coating areas SP1 to SP3, the undercoat and the cooler coating may be overlapped (especially in the case of metallic coating), or the solid coating may be applied (solid coating). It is possible to overlap several times, such as two paintings).

In addition, each line CL1-CL3 shown in FIG. 1 may be made of only the entire intermediate coating, only the entire outer coating, or a part of the coating lines in the intermediate coating, and the remaining coating lines may be the outer coating. It is appropriately selected as the division of each painting line. The division of paint, coating and coating lines in the above-described coating zone is the same shape as long as there is no particular limitation in the following examples. FIG. 2 shows setting of separate coating conditions in coating lines CL1-C12 shown in FIG.

[Table 2]

In Table 2, the second coating line corresponds to the high temperature heat-drying paint of the improvement of the finish coating of the painted surface by preheating. In addition, in the coating line CL3, in addition to suppressing occurrence of defects or bubbles, the coating line CL3 is adapted to a high temperature heat-drying paint.

The paint hardening model in the coating line CL1 in Table 2 is shown in FIG. In FIG. 4, 140 degreeC x 20-minute hardening type | mold is used as a coating material (coating which needs to dry at 140 degreeC for 20 minutes by making the crosslinking density of a paint into 75% used as the reference value of heat-drying completion).

In FIG. 4, the crosslinking density of the paint reaches 40% by preliminary drying at 130 DEG C for 10 minutes in the preliminary drying furnace PB1. It hardens to the extent that it does not give. In the main drying furnace (MB), it is understood that drying may be performed at 150 ° C. for 13 minutes to make the crosslinking degree 75% in the state of 40% crosslinking degree (time point indicated by α in FIG. 4). Moreover, in FIG. 4, it is understood that hardening with a crosslinking density of 40% is obtained even if preliminary drying for 140 degreeC * 5 minutes is performed in the preliminary drying stand PB1.

The coating material hardening model in the coating line CL3 in Table 2 is shown in FIG. In FIG. 5, although 150 degreeC x 20 minute hardening type | mold is used as a coating material, the meaning shown in FIG. 5 is the same as that of FIG. 4 mentioned above, and the overlapping description is abbreviate | omitted. 2 shows another embodiment of the present invention. In the present embodiment, the first and second coating lines CL11 and CL12 are provided in the coating area A, and the third and fourth coating lines CL13 and CL14 in the coating area B. Is installed.

In FIG. 2, MB is the main drying furnace, MBL is the drying line, SP11-SP14 is the coating zone, ST11-ST14 is the setting zone, PB11-PB14 is the preliminary drying zone (preliminary drying furnace), KL11 and KL12 are common lines, X11 and X12 are branching portions, Y11-Y13 are joining portions, and J11-J13 are first-third transfer devices.

In FIG. 2, the first and second coating lines CL1 and C12 in the coating area A are for intermediate coating, and the third and fourth coating lines CL13, (CL14) is painted with a painting. The to-be-coated object W is supplied to the common line KL11 in the coating area A by the apparatus J11 for carrying in to-be-painted object supply line MBL-1. Then, the object to be coated (W) after passing through the first coating line (CL11) or the second coating line (CL12) in the common line (KL11), after passing through the joining portion (Y11) (J13) Is reached, and is transferred to the drying line MBL connected to the main drying furnace MB by this third stacking device J13.

The to-be-coated object W which has completed the intermediate painting is supplied to the common line KL12 in the coating area B by the 2nd loading apparatus J12 in the to-be-coated object supply line MBL-2. The object to be coated W passes through the third painting line CL13 or the fourth painting line CL14 in the common line KL12 and reaches the third conveying device J13 through the confluence portion Y12. By the third transfer device (J13) is transferred to the drying line (MBL) connected to the main drying furnace (MB).

Moreover, the line between the 1st or 2nd loading apparatus J11, J12 to the joining part Y13 is used to hold | maintain the carriage D. Table 3 shows a coating example using the configuration shown in FIG. 2.

Table 3

In the example shown in FIG. 2, for example, the coating in the coating area A may be painted with a paint coating and a two-color color (divided into two colors). In this case, one coating line ( CL13) may be used for the painting of one color, and another coating line CL14 may be used for the painting of a two-color killer.

3 shows another embodiment of the present invention. In the present embodiment, the first and second coating lines CL21 and CL22 are provided in the coating region C, and the third and fourth coating lines CL23 and ( CL24) is installed. In this FIG. 3, MB is the main drying furnace, MBL is the drying line for the coating material supply line, SP21-SP24 is the coating area, ST21-ST24 is the setting area, and PB21-PB24 is the preliminary rolling area. (Preliminary drying furnace), K121 and K122 are common lines, X21 and X22 are branching portions, Y21 and Y22 are joining portions, and J21 and J22 are first and second transfer devices.

In this FIG. 3, each coating line CL21-CL24 is used for the painting. However, in the first and second coating lines CL21- (CL22) in the coating area C, the rotation of the coated object W is not particularly required in terms of paint drying (preliminary drying of the paint). Coating method is performed.

On the other hand, in the 3rd and 4th coating lines CL3 and CL4 in the coating area D, the to-be-painted object W is centered on the horizontal axis about the drying (predrying) of paint. A rotary coating method for rotating is performed. That is, in the painting zones SP23 and SP24, if left in the preliminary drying zones PB23 and PB24 with respect to at least the longitudinal surface of the workpiece W, the paint does not flow down due to the influence of gravity. The paint is applied to a thickness above the so-called spill limit.

In the preliminary drying furnaces PB23 and PB24, the falling of the paint is prevented from occurring, so that the object to be coated W rotates about the horizontal axis. At this time, the rotational speed of the coated object W is a rotational speed at which the flow of paint can be prevented from occurring due to gravity, and the rotation of the paint does not occur due to the centrifugal force caused by the rotation. It becomes below speed.

The coating material W after passing through the pre-drying furnaces PB23 and PB24 by pre-drying the paint while rotating the coating object W in the pre-drying furnaces PB23 and PB24 is a coating material. Under the influence of the force of gravity, it hardens enough to prevent the occurrence of dripping.

As a carrier used in the 3rd, 4th painting line CL23, CL24 in the painting area | region D for performing a rotating apparatus as mentioned above, the ash which has a function which rotates the to-be-painted object W is carried out. The dedicated transport vehicle D2 is used. On the other hand, the carriage used for the 1st and 2nd coating lines CL21 and CL22 in the coating area D, and the carriage used for the drying line MBL carry the to-be-painted object W. FIG. The general transport vehicle D, which does not have a function of rotating, is used.

In addition, since such a rotary coating is disclosed in Japanese Unexamined Patent Publication No. 63-248749 described above, the detailed description thereof is omitted. In the structure of FIG. 3, the to-be-painted object W is conveyed to the 1st conveying apparatus J21 according to the drying line MBL using the general transportation vehicle D. FIG. When the to-be-coated object W is suitable to apply a long shape, it moves to the common line K121 (general transport vehicle) of the coating area C by the 1st loading apparatus J21.

Moreover, the to-be-coated object W by which rotation coating is performed is moved to the common line K122 (rotation | carrier transport vehicle D2) of the coating area D by the 1st mounting apparatus J21. After the preliminary drying in each painting line CL21-CL24 is completed, the to-be-painted object W is moved to the rolling line MBL (general transport vehicle) by the 2nd transfer apparatus J22.

And the to-be-coated object W finally passes through main drying furnace MB, and final drying of a coating material is performed. Table 4 shows a coating example of the configuration in FIG. 3.

Table 4

In Table 4, although the same kind of paint is used in the entire coating lines C121 to CL23, the first and second coating lines CL21, CL22, CL23, and CL24 are used. The thickness of the applied paint becomes thick.

In addition, the to-be-coated object W becomes the preliminary drying furnace PB21, PB22 in the 1st, 2nd phase line CI-21, CL22. Further, in the third and fourth painting lines CL23 and CL24, the setting zones ST23 and ST24 may be rotated around the horizontal axis as necessary.

In addition, in FIG. 3, the overcoating may be performed, or the intermediate coating may be performed by rotating coating.

As described above, the vibration isolating chamber BB may be provided even in the second and third cases. In addition, as in the case of FIGS. 1 to 3, a cooling chamber may be provided at the outlets of the preliminary drying furnaces PB1-(PB3), (PB11) (-PB14), and (PB21)-(PB24). 2, the cooling chamber CR is shown by the constant chain line. Again, as in the case of FIG. 1 to FIG. 3, an air blowing chamber may be installed at the entrance of the main drying furnace (MB) to blow dust attached to the painted surface, and in FIG. It is indicated by.

In addition to this, after completion of the preliminary drying in one coating line, it is possible to pass the other drying line and pass the main drying furnace MB after passing the other coating line without passing the conditional furnace MB. As an example, in the example shown in FIG. 2, in the case where two out-of-color paints are applied using the paint lines CL13 and CL14, first, the paint is coated with a paint of a predetermined color in the paint line CL13.

The coating line CL13 is transferred to the painting line CL14 using the common line KL12 without being transferred to the drying line MBL by the apparatus J13 for carrying the transparent workpiece W. It supplies and transfers the to-be-coated object W after passing through the preliminary drying furnace PB14 of this coating line CL14 to the drying line MBL by the 2nd transfer apparatus J12 as a ratio, and to the main drying furnace. The main drying at (MB) may be performed.

In this way, the number of coating lines to which the workpieces W are sequentially supplied without passing through the main drying furnace NIB is not limited to two but may be three or more. Of course, when moving the object to be coated (W) between the coating lines in such a relationship, it is also possible to use a separate carrying device.

In addition, since the main drying furnace MB does not need to perform a separate operation on the object to be coated W, the conveying pitch of the object to be coated W in the main drying furnace NIB It is smaller than the feed pitch of the workpiece W.

Claims (11)

A coating area for applying the coating to the coated object W and a plurality of coating lines (CL1) to (CL3) each provided with preliminary rolling paths (PB1) to (PB3) for predrying the coating applied in the coating area. ) And one main drying furnace (MB) set to be jointly used for the plurality of coating lines CL1 to CL3, and after the preliminary drying is completed, the plurality of coating lines CL1. A coating-drying method, characterized in that the to-be-coated (W) in CL3) is supplied to the above-mentioned main drying furnace MB, and this drying is performed in the main drying furnace MB. The drying condition in the main drying furnace MB is set to a predetermined common condition condition, and the drying conditions of the plurality of preliminary drying furnaces PB1 to PB3 are performed in the corresponding coating line. Coating drying method, characterized in that each set independently according to the coating conditions. According to claim 1, wherein the workpiece (W) is passed through two or more coating lines in sequence without passing through the main drying furnace (MB) in the middle two or more pre-drying is carried out and the condition after the pre-drying is finished in the final coating line Painting drying method characterized in that the main drying in the furnace (MB). The rotating transport vehicle (D2) according to claim 1, which is independent of the drying line (MBL) connected to the main drying furnace (MB), and has a function of rotating the coated object (W) about an approximately horizontal axis. Rotational painting line for driving) and non-rotational painting line run by general transport vehicle (D) which does not have the function of rotating the workpiece (W), drying line (MBL) and rotational painting line Coating drying method, characterized in that the exchange of the object (W) to be exchanged. The method according to claim 1, wherein in some of the plurality of coating lines (CL1) to (CL3), between the coating zone and the preliminary drying furnaces (PB1) to (PB3) than the preliminary drying furnaces (PB1) to (PB3). Coating drying method characterized in that the preliminary heat is performed at a low temperature. A number of painting lines and one main drying system having pre-drying furnaces (PB1) to (PB3) for pre-drying the coating applied in the coating zone and the coating zone for applying the coating to each coating (W). The drying line MBL set to pass through the MB and the main drying furnace and the coated object W moving independently from the plurality of coating lines, respectively, than the preliminary drying furnaces PB1 to PB3. Painting drying apparatus, characterized in that it has a conveying means for transferring from the angular length line to the drying line (MBL) in the downstream position. 7. The conveying apparatus (J1) according to claim 6, wherein the drying line MBL is configured independently of the plurality of painting lines, and the conveying means transfers the coated object from each painting line to the drying line MBL. A coating and drying apparatus, characterized by (J2). The method according to claim 6, wherein two or more coating lines of the plurality of coating lines are connected to pass through the two or more preliminary drying passages in turn passing through the two or more coating lines (W) not passing through the main drying furnace (MB), The coating material (W) after passing through the pre-drying furnace of the painting line through which the painting object passes in the last part of the painting line is transferred to the drying line (MBL) by the transfer means. Painting drying apparatus. According to claim 6, wherein the coating line of a portion of the coating line is configured independently of the other coating line and the drying line (MBL) and the to-be-painted vehicle for traveling the coating line of the above-described coating ( And a rotary transport vehicle (D2) having a function of rotating W) about a horizontal axis. The temperature of the preliminary drying furnaces (PB1) to (PB3) in the above part of the coating line is left as it is above the temperature at which the flow of paint occurs due to the influence of gravity. A coating drying device, characterized in that the coating (W) is rotated about a horizontal axis to prevent the paint from flowing down during the preliminary drying in one of the painting lines (PB1) to (PB3). 7. The preliminary drying furnace (PB1) to (PB3) according to claim 6, wherein the preliminary drying furnace (PB1) to (PB3) is disposed between the painting zone and the preliminary drying furnaces (PB1) to (PB3) in a portion of the painting lines (CL1) to (CL3). A coating drying apparatus, characterized in that a preheating zone configured to perform preliminary heating lower than temperature.