JP2004267834A - Intermediate topcoating wet-on-wet coating method and coating film dryer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for drying a coating film capable of achieving the contraction and energy saving of a process, and a dryer therefor. <P>SOLUTION: The intermediate topcoating wet-on-wet coating method has a first process for coating a car body with intercoating, a second process for respectively measuring the applied solid components of the intercoating films applied to a plurality of the regions of the car body, a third process for controlling a drying conditions by respective regions on the basis of the applied solid components of the respective regions measured in the second process to pre-dry the intercoating film so that the applied solid component of the intercoating film becomes a predetermined range, a fourth process for coating the intercoating film with topcoating and a fifth process for drying and curing the intercoating film and the topcoating film at the same time. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
【Technical field】
The present invention relates to a coating method and a drying apparatus for a coating film, and more particularly to a coating method and a drying apparatus for a coating film which are preferably applied to an intermediate coating and a top coating wet-on-wet coating system using an automobile body as an object to be coated.
[0002]
[Background Art]
In the conventional three-coat coating method, an electrodeposition coating, which is an undercoat, is applied, followed by drying, then an intermediate coating, followed by drying, and finally, a top coating, followed by drying. . In such a three-coat coating method, a drying device is required for each of the intermediate coating and the top coating, and there is room for improvement in process space and energy cost. For this reason, for the purpose of reducing the coating process and reducing the energy cost, a two-coat coating method in which the intermediate coating film and the top coating film are applied wet-on-wet has been studied.
[0003]
In this two-coat coating method, an electrodeposition coating is applied, followed by drying, an intermediate coating, a wet-on-wet top coating, and the intermediate coating film and the top coating film are simultaneously dried. Things. Thus, the conventional method requires two drying devices, the intermediate coating drying device and the top coating drying device, but only one drying device is sufficient, so that the process space can be reduced and the energy cost can be reduced.
[0004]
By the way, when the intermediate coat and the top coat are applied on a wet-on-wet basis, it is necessary to evaporate a predetermined amount of the solvent contained in the intermediate coat after applying the intermediate coat, and then to apply the top coat before sagging or waki. Or poor coating quality such as poor skin occurs. For this reason, a step (also called a flash-off step) for forcibly drying the intermediate coating film is provided between the intermediate coating and the top coating.
[0005]
In the flash-off step, the solid content of the intermediate coating film (solid content of the coating film in a state of being applied to the substrate, hereinafter also referred to as coating NV value) is 90% by weight to 95% by weight. It is considered desirable to force-dry to a maximum.
[0006]
However, the horizontal parts such as the roof, hood and trunk lid have different heights like the automobile body, and the vertical parts such as the fenders, doors, rear fenders and pillars have complicated shapes with different vehicle widths. Therefore, it is extremely difficult to control the coating NV values of all the parts in the above-mentioned appropriate range with a fixed amount of hot air blown out from the forced drying device in the flash-off step.
[0007]
For this reason, in the conventional forced drying apparatus, the temperature of the hot air is set to be low and the amount of air is set to be small, so that the coating NV value is controlled as uniformly as possible. The length and the transit time had to be long, and it was difficult to realize a reduction in the number of steps and a reduction in energy cost.
[0008]
[Patent Document 1] JP-A-2002-113410
DISCLOSURE OF THE INVENTION
SUMMARY OF THE INVENTION An object of the present invention is to provide a method and an apparatus for drying a coating film, which can reduce the number of steps and save energy.
[0010]
To achieve the above object, according to the present invention, a first step of applying an intermediate coating to an automobile body, and measuring the applied solid content of the intermediate coating film at a plurality of portions of the automobile body, respectively. A drying step for each part based on the solid content of each part measured in the second step, and the coating solid content of the intermediate coating film is set to a predetermined value. A third step of pre-drying the intermediate coating film so as to be in a range, a fourth step of applying a top coating material on the intermediate coating film, and simultaneously applying the intermediate coating film and the top coating film. And a fifth step of drying and curing.
[0011]
To achieve the above object, according to the present invention, a coating solid content measuring means for measuring a coating solid content of a wet coating film applied to an automobile body for each of a plurality of sites, A drying unit that is provided immediately after the measuring unit and supplies thermal energy to each of the parts of the vehicle body; and the respective parts based on the coating solid content of each part measured by the coating solid content measuring means. And a control means for controlling the drying conditions of the drying means for each part so that the coating solid content of the coating film falls within a predetermined range.
[0012]
In the present invention, the solid content of the wet intermediate coat is measured for each part of the automobile body after applying the intermediate coat and before applying the top coat. Then, based on the measured solid content of each part, drying conditions are controlled for each part, and the intermediate coating film is pre-dried.
[0013]
As a result, even in the case of an automobile body having a complicated shape, the coating solid content can be controlled to an appropriate range for all the parts, and coating defects such as armpits due to a low coating solid content and a coating defect. It is possible to prevent the occurrence of defective painting such as defective skin due to a high solid content. In addition, since predrying is performed by controlling the drying conditions for each part, it is possible to reduce the size of the process and save energy.
[0014]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
First, a coating method according to an embodiment of the present invention will be described. FIG. 1 is a process chart showing a coating method according to an embodiment of the present invention.
[0015]
In the present embodiment, an automobile body is used as an object to be coated, and the inner and outer plates of the automobile body are subjected to electrodeposition coating as undercoating, and then dried and cured. Next, an intermediate coat is applied to the inner and outer plates of the automobile body on which the electrodeposition coating film is formed, and after pre-drying, a top coat is applied on a wet-on-wet basis, and the intermediate coat and the top coat are simultaneously dried. Let it cure.
[0016]
The electrodeposition coating material, the intermediate coating material, and the top coating material used in the present embodiment are not particularly limited, and conventionally known coating materials can be used.
[0017]
In particular, in the present embodiment, the following drying device 1 is used in a preliminary drying step (flash-off step) between the time when the intermediate coating is applied and the time when the top coating is applied.
[0018]
FIG. 2 is a block diagram showing the coating film drying apparatus 1 according to the embodiment of the present invention, and FIG. 3 is a perspective view showing the coating film drying apparatus 1 according to the embodiment of the present invention.
[0019]
The drying apparatus 1 of the present embodiment is provided in, for example, a step in a middle coat booth or in a step between the middle coat booth and the top coat booth. The drying device 1 includes a coating solid content measuring device 11 that measures the coating solid content of the intermediate coating film in a wet state applied to the automobile body B for each of a plurality of parts, and immediately after the coating solid content measuring device 11. And a hot air blowing device 21 for supplying hot air to each portion of the vehicle body B, and a coating solid content of each portion of the vehicle body B measured by the coating solid content measuring device 11. A controller 31 for controlling the drying conditions of the hot-air blowing device 21 for each part so that the coating solid content of the coating film is within a predetermined range.
[0020]
As shown in FIGS. 2 and 3, the coating solid content measurement device 11 includes a coating solid content measurement unit 112 a provided on a ceiling 111 a of an arch 111 that straddles a transport path of the automobile body B, and a side surface of the arch 111. It has a coating solid content measuring unit 112b provided on the upper part 111b and a coating solid content measuring unit 112c provided on the lower side surface 111c of the arch 111.
[0021]
The coating solid content measuring section 112a on the ceiling mainly measures the coating solid content of the intermediate coating film applied to a horizontal portion such as a hood, a roof, a trunk lid, or a back door of the automobile body B. The coating solid content measuring section 112b provided on the upper side 111b mainly measures the coating solid content of the intermediate coating film applied to the upper vertical portion such as the front pillar, center pillar, and rear pillar of the vehicle body B. I do. The coating solid content measuring unit 112c provided in the lower side 111c is mainly used for measuring the coating solid content of the intermediate coating film applied to the lower vertical portion such as the front fender, front door, rear door, and rear fender of the vehicle body B. Is measured. Note that, depending on the type of the vehicle body B, the above-described portion may not exist or there may be a portion other than the above-described portion, but these classifications can be appropriately selected according to the shape of the vehicle body B. .
[0022]
The coating solid content measuring device 11 of the present embodiment is not particularly limited as long as the coating solid content of a wet coating film applied to the automobile body B can be measured in real time. Can be.
[0023]
The first type irradiates visible light to a wet coating film as an object to be measured, captures image data of the reflected light, and resolves the image data to analyze the unevenness amount of the coating film surface. Then, a coating solid content measuring device for calculating a coating solid content from the data of the amount of unevenness, the type of the intermediate coating material and the dilution solvent, and environmental data such as the temperature and humidity of the booth. This apparatus can measure the thickness of the wet coating film by the same principle.
[0024]
The second type irradiates the wet film, which is the object to be measured, with infrared rays, and measures the amount of absorption, thereby determining the solvent contained in the wet film (water for water-based paint, thinner for solvent-based paint). ) Is a coating solid content measuring device which calculates an amount and calculates a coating solid content from the residual solvent amount.
[0025]
Each of these coating solid content measuring devices 11 can measure the coating solid content of a wet coating film in real time.
[0026]
As shown in FIGS. 2 and 3, the hot-air blowing device 21 includes a hot-air blowing device 21a provided on a ceiling portion of a transport path of the vehicle body B and a hot-air blowing device 21b provided on an upper stage on both sides of the transport path. And a hot air blowing device 21c provided at a lower stage on both sides of the transport path.
[0027]
The hot air blowing device 21a provided on the ceiling mainly blows hot air to a horizontal portion such as a hood, a roof, a trunk lid or a back door of the automobile body B. The hot-air blowing device 21b provided at the upper part of both sides mainly blows hot air to a vertically upper part such as a front pillar, a center pillar, and a rear pillar of the vehicle body B. The hot-air blowing device 21c provided at the lower part of both sides mainly blows hot air to a vertically lower part of the vehicle body B such as a front fender, a front door, a rear door, and a rear fender. These classification ranges correspond to the classification ranges of the coating solid content measuring units 112a to 112c described above.
[0028]
The hot air blowing device 21a provided at the ceiling, the hot air blowing device 21b provided at the upper part of both sides, and the hot air blowing device 21c provided at the lower part of both sides control the temperature and the wind speed of the hot air independently of each other. The control device 31 instructs each of these three hot air blowing devices 21a to 21c from the control device 31 for the temperature, speed and supply time of the hot air.
[0029]
It is desirable that the distances between the outlets of these three hot air blowing devices 21a to 21c and the vehicle body B be as equal as possible. Therefore, the hot air blowing device 21a at the ceiling can be moved up and down by a lifting device (not shown). In synchronization with the conveyance of the body B, for example, when the hot air is blown on the hood, the airbag lowers, and when hot air is blown on the roof, the aircraft rises. Similarly, it is more preferable that the hot air blowing device 21c provided at the lower part on both sides is configured to move forward and backward in the width direction.
[0030]
The control device 31 takes in the measurement data of the coating solid content from each of the three measuring units 112a to 112c of the coating solid content measuring device 11 at predetermined time intervals, and refers to the preliminary drying condition table shown in FIG. The pre-drying conditions to be performed are extracted, and the hot air blowing devices 21a to 21c corresponding to the three measuring units 112a to 112c are instructed to blow the hot air of the extracted conditions.
[0031]
In the examples shown in FIGS. 2 and 3, only one hot air blowing device 21 a to 21 c is installed, but it is also possible to install this in multiple stages.
[0032]
Next, the operation will be described.
FIG. 4 is a flowchart showing a control procedure of the coating film drying apparatus according to the embodiment of the present invention, and FIG. 5 is a view showing a drying condition table according to the embodiment of the present invention.
[0033]
When the automobile body B on which the intermediate coating film is formed in a wet state is conveyed and passes through the arch 111, data of the coating solid corresponding to each part is obtained from the three coating solids measuring units 112a to 112c. It is taken into the control device 31 (step 1).
[0034]
When the data of the solid content of the coating is captured, the hot air temperature, the wind speed and the drying time under the corresponding predrying conditions are extracted with reference to the predrying condition table shown in FIG. 5 for each portion (step 2). The hot-air blowing device 21 of the present embodiment is composed of three hot-air blowing devices 21a to 21c, and the hot-air temperature, the wind speed, and the blowing time can be controlled independently of each other. As shown in FIG. Is divided into 5% by weight intervals, and hot air conditions suitable for each are verified so that the applied solid content after predrying becomes an ideal value of 90 to 95% by weight. Control.
[0035]
In step 3, the conditions of the hot air temperature, the drying time and the hot air speed extracted from the preliminary drying condition table shown in FIG. 5 are sent to the corresponding hot air blowing devices 21a to 21c. Thus, in each of the hot-air blowing devices 21a to 21c, the preliminary drying is performed under the condition corresponding to the measured value of the solid content of each portion of the vehicle body B. As a result, overcoating is performed when the applied solid content of the intermediate coating film is in the ideal range of 90 to 95% by weight over the entire vehicle body B.
[0036]
The embodiments described above are described for facilitating the understanding of the present invention, and are not described for limiting the present invention. Therefore, each element disclosed in the above embodiment is intended to include all design changes and equivalents belonging to the technical scope of the present invention.
[Brief description of the drawings]
FIG. 1 is a process chart showing a coating method according to an embodiment of the present invention.
FIG. 2 is a block diagram showing a coating film drying apparatus according to an embodiment of the present invention.
FIG. 3 is a perspective view showing a coating film drying apparatus according to an embodiment of the present invention.
FIG. 4 is a flowchart showing a control procedure of a coating film drying apparatus according to the embodiment of the present invention.
FIG. 5 is a diagram showing a drying condition table according to the embodiment of the present invention.
[Explanation of symbols]
1. Drying device 11: Coating solid content measuring device (Coating solid content measuring means)
21 hot air blowing device (drying means)
31 ... Control device (control means)
B ... Car body

Claims (7)

A first step of applying an intermediate coating to the car body;
A second step of measuring the applied solid content of the intermediate coating film in each of a plurality of parts of the automobile body;
Based on the solid content of each part measured in the second step, the drying conditions are controlled for each part so that the solid content of the intermediate coating film falls within a predetermined range. A third step of pre-drying the coated film;
A fourth step of applying a top coat on the intermediate coat,
And a fifth step of simultaneously drying and curing the intermediate coating film and the top coating film. Coating solid content measuring means for measuring the coating solid content of the wet coating film applied to the automobile body for each of a plurality of sites,
A drying unit that is provided immediately after the coating solid content measuring unit and supplies thermal energy to the respective parts of the vehicle body,
Based on the coating solid content of each part measured by the coating solid content measuring means, the drying of the drying means is performed for each part so that the coating solid content of the coating film of each part falls within a predetermined range. A coating film drying device, comprising: a control unit for controlling conditions. The drying means, while supplying hot air to the vehicle body as heat energy, has a means for controlling the temperature and wind speed of the hot air,
The control means is based on the coating solid content of each part measured by the coating solid content measuring means, so that the coating solid content of the coating film of each part is within a predetermined range, for each of the respective parts 3. The coating film drying apparatus according to claim 2, wherein the temperature and the speed of the hot air supplied from the drying unit are controlled. The coating film drying apparatus according to claim 3, wherein the control unit controls the temperature and the speed of the hot air supplied from the drying unit independently. The coating solid content measuring means irradiates visible light to the coating film to be measured, acquires a reflection image thereof, calculates the amount of unevenness of the coating film surface from the reflection image, and calculates the amount of unevenness and coating. The coating film drying apparatus according to any one of claims 2 to 4, wherein the coating solid content is calculated based on the applied coating data and coating environment data. 5. The coating solid content measuring unit according to claim 2, wherein the coating film that is the object to be measured is irradiated with infrared rays to measure the amount of absorption, and the coating solid content is calculated from the absorption amount. Equipment for drying coating films. The coating film drying apparatus according to any one of claims 2 to 6, wherein the plurality of parts of the automobile body are at least a horizontal part, a vertical part upper part, and a vertical part lower part.

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