JP3407583B2 - Apparatus and method for producing coated steel sheet - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus and method for producing a coated steel sheet by continuous coating.

[0002]

2. Description of the Related Art Painted steel sheets are used in a wide range of fields such as home appliances and building materials. The coating film of this coated steel sheet has the required thickness, color, workability and scratch resistance for each application of the coated steel sheet. It is required to have the function.

Generally, a coated steel sheet is manufactured by continuously running the steel sheet online on which a coating apparatus, a baking furnace, etc. are arranged. That is, the steel sheet is first coated with a coating material by a coating device and then baked in a baking oven. In addition, a coating film thickness measuring instrument, a colorimeter, and a plate thermometer that measures the surface temperature of the steel sheet (hereinafter referred to as "plate temperature") are arranged online to control the coating film thickness and color. There is.

In Japanese Patent Laid-Open No. 63-7870, the maximum temperature for baking of the detected steel sheet is detected by detecting the surface temperature, the coating film thickness and the coating surface color of the steel sheet on which the coating film on the outlet side of the baking furnace is formed. A coating film control device is disclosed which controls the temperature in the furnace based on the temperature and performs feedback control that adjusts the coating amount based on the detected coating thickness and the color of the coating surface.

Further, in Japanese Patent Laid-Open No. 2-222750, the coating thickness is controlled by a coating thickness meter which measures the coating thickness from the weight of the coating material supplied, and the color measurement is provided in the downstream of the drying / baking process. Detect the color difference signal by the meter, based on the management standard for each paint color prepared separately according to this detected color difference signal,
A control method for changing the control target value of the coating thickness or the baking temperature is disclosed.

[0006]

However, when a coated steel sheet is manufactured online by using the coating film control device disclosed in the above-mentioned Japanese Patent Laid-Open No. 63-7870, or the above-mentioned Japanese Patent Laid-Open No. When a coated steel sheet is manufactured using the control method disclosed in Japanese Patent No. 222750, the color of the product of the coated steel sheet may change.

With respect to this color variation, the color is measured without considering the plate temperature of the steel sheet at the time of online color measurement, so that accurate color measurement has not been performed, and based on the measurement result. This is because the coated steel sheet was manufactured by controlling the color.

As described above, the conventional apparatus and method for manufacturing a coated steel sheet has a problem that the color of the product of the coated steel sheet varies. The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a coated steel sheet manufacturing apparatus and a manufacturing method for continuously manufacturing a coated steel sheet with a stable color in a coating line.

[0009]

In order to solve the above-mentioned problems, the invention corresponding to claim 1 provides a coated steel plate manufacturing apparatus for manufacturing a coated steel plate by continuously applying a coating material to a running steel plate. A coating means for coating a running steel sheet with a coating film thickness control function to form a coating film of a specified thickness on the steel sheet, and a steel plate with a baking temperature control function provided after the coating means. Baking means for controlling the surface temperature of the paint to a specified temperature to bake the applied paint on a steel plate, and cooling the steel plate with the paint baked with a cooling control function provided after the baking means to a specified cooling state. Cooling means, a color measuring means that is provided at a subsequent stage of the cooling means to measure the color of the cooled steel sheet, and a plate temperature measuring means that measures the surface temperature of the steel sheet near the color measurement position by the color measuring means. Then, the measurement result by the plate temperature measuring means The cooling control function of the cooling means controls the cooling state of the steel sheet on the basis of the plate temperature signal value of, and the control target value of the coating thickness control function of the coating means or the baking based on the color signal value of the measurement result by the color measuring means. It is an apparatus for manufacturing a coated steel sheet for changing at least one of control target values of the baking temperature control function of the means.

In the coated steel sheet producing apparatus according to the first aspect of the present invention, the cooling means brings the surface temperature of the steel sheet into a state suitable for color measurement, and the coating film is based on the color signal value measured in this state. The thickness and the surface temperature of the steel plate during baking are changed.

The color condition can be controlled by controlling the thickness of the coating film and the surface temperature of the steel plate within an allowable range. Therefore, by appropriately controlling the thickness of the coating film and the surface temperature of the steel sheet on the basis of the measurement result of the appropriate color, it is possible to manufacture a coated steel sheet having a stable color in a continuous coating line.

The invention according to claim 2 is a method for producing a coated steel sheet, wherein a coating material is continuously applied to a running steel sheet to produce a coated steel sheet, and a coating film having a specified thickness is formed. A coating means with a film thickness control function applies paint to a steel plate running and controls the surface temperature of the steel plate after the paint is applied to a specified temperature. Baking, the cooling means having a cooling control function for controlling the cooling state of the steel sheet after the paint is baked cools the steel sheet, and the color of the cooled steel sheet is measured by the color measuring means, and the color by the color measuring means is measured. The plate temperature measuring means provided in the vicinity of the measuring position measures the surface temperature of the steel plate near the color measuring position, and the cooling control function of the cooling means is based on the plate temperature signal value of the measurement result by the plate temperature measuring means. Control the cooling state of In the manufacturing method of the coated steel sheet, at least one of the control target value of the coating film thickness control function of the coating means or the control target value of the baking temperature control function of the baking means is changed based on the color signal value of the measurement result by the color measuring means. Therefore, it is possible to obtain the same effect as that of the first aspect.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a block diagram showing a configuration example of a coated steel sheet manufacturing apparatus adopting a coated steel sheet manufacturing method according to an embodiment of the present invention.
a, 1b1c) along a conveying path, a coating device 2, a baking oven 5, a plate temperature meter 9, a cooling zone 10, a coating film thickness meter 12, and a colorimeter 1.
3. A color measuring plate thermometer 14 is installed.

The coating device 2 for coating the steel plate 1a is
It comprises a pickup roll 2a, an applicator roll 2b and a backup roll 2c, and the pickup roll 2a and the applicator roll 2b are rotationally driven by an electric motor (not shown). Pickup roll 2
A picks up the paint from the paint pan 3 and supplies it to the applicator roll 2b. Applicator roll 2b
The paint is adhered to the steel plate 1a that comes into contact with it.

The pickup roll 2a and the applicator roll 2b are provided with a roll gap adjusting device 4 including a servomotor and a screw mechanism, and the amount of paint adhered is adjusted by the gap between the rolls.

A baking oven 5 is arranged on the outlet side of the coating apparatus 2. The baking furnace 5 heats the coated steel plate 1b by supplying the hot air gas in which the fuel gas is burned, and the paint is baked on the steel plate 1b.

The amount of fuel gas is adjusted by the opening of the fuel control valve 6, and the amount of hot air is adjusted by the rotation speed of the motor 8 which drives the hot air blower 7. That is, the maximum baking plate temperature in the baking furnace 5 is controlled by adjusting the opening degree of the fuel control valve 6 and the rotation speed of the motor 8.

Immediately after the baking furnace 5, a plate thermometer 9 for detecting the maximum baking temperature of the coated steel plate 1c is provided. As the plate thermometer 9, for example, a non-contact type radiation thermometer can be used.

A cooling zone 10 for cooling the steel plate 1c after baking is provided at the subsequent stage of the plate thermometer 9, and the plate temperature of the steel plate 1c is controlled by the opening degree of the water amount control valve 11. Further, a coating film thickness meter 12 for measuring the thickness of the coating film is provided on the rear side.

A colorimeter 13 for measuring the color of the coated surface is provided after the coating film thickness meter 12. Here, for example, an infrared coating film thickness meter can be used as the coating film thickness meter 12. In the vicinity of the measurement position of the colorimeter 13 (hereinafter referred to as the colorimeter section),
A color measuring plate thermometer 14 for measuring the plate temperature is provided so that the plate temperature of the steel plate 1c passing through the color meter portion can be measured. As the plate thermometer 14 described above, for example, a non-contact type radiation thermometer can be used for the plate thermometer 14 for color measurement.

The plate thermometer 9, the coating film thickness meter 12, the color meter 13 and the color measuring plate thermometer 14 are respectively provided with comparison calculators 15-1.
8 and dead band circuits 19 to 22 are connected. The dead zone circuits 19 to 22 prevent hunting of the control system.

The manufacturing instruction file 23 includes the thickness of the steel plate,
Board width, length, coating film thickness setting value, coating film thickness tolerance,
Dead band set value of paint film, type of paint to be applied, color characteristics (relationship between paint film thickness and color after baking), optimum baking maximum plate temperature and its dead band set value, color set value of painted surface of product and its The dead zone set value and the like are recorded.

The main computer 24 obtains a required roll gap according to the coating film thickness setting value, and sets the roll gap adjusting device 4 of the coating device 2 via the coating film thickness adjusting device 25. Further, the main computer 24 uses the width of the steel plate 1, the thickness of the steel plate, the type of paint,
An appropriate opening of the fuel control valve 6 and the amount of hot air are preliminarily determined based on information such as the optimum baking maximum plate temperature, and based on the determined opening of the fuel control valve 6, a fuel valve opening regulator 26 is used. Then, the opening of the fuel control valve 6 is controlled, and the rotation speed of the motor 8 is controlled via the hot air flow controller 27 based on the determined hot air flow, whereby the state of the baking furnace 5 is set.

Further, the main computer 24 determines the appropriate water quantity control valve 11 based on the signal from the color measuring plate thermometer 14 provided in the color measuring unit of the steel plate 1c coming out of the baking furnace with the coating film formed. The degree of opening is determined, and based on the determined degree of opening of the water amount adjusting valve 11, the water amount adjusting valve 11 is passed through the water amount adjuster 28.
Is controlled, and the state of the cooling zone 10 is set by this, and the temperature of the steel plate 1c of the colorimeter part is appropriately controlled.

That is, the main computer 24 determines the required coating film thickness and fuel based on the signals from the manufacturing instruction file 23, the plate thermometer 9, the coating film thickness meter 12, the colorimeter 13 and the color measuring plate thermometer 14. Calculate the supply amount, hot air amount and plate temperature of the colorimeter,
The calculation result is used as a coating film thickness controller 25, a fuel valve opening controller 26,
Control signals are output to the roll gap control device 4, the fuel control valve 6, the motor 8 for controlling the hot air flow rate, and the water flow rate control valve 11 via the hot air flow rate control device 27 and the water flow control device 28, respectively.

As described above, the apparatus for manufacturing a coated steel sheet of this embodiment is provided with the cooling zone 10 at the rear side of the baking furnace 5, and further at the rear side of the cooling zone 10 the colorimeter 13 and the color measuring device. A plate thermometer 14 is provided. This manufacturing apparatus feedback-controls the cooling ability such as the cooling temperature of the steel plate 1c passing through the cooling zone 10 based on the plate temperature of the colorimeter unit measured by the colorimeter 14 for color measurement. It is possible to keep the plate temperature during color measurement within the range of the target set value suitable for color measurement.

FIG. 2 is a diagram showing an example of the spectral intensity distribution of a red-painted steel sheet, where the horizontal axis shows the wavelength (nm) and the vertical axis shows the reflectance (%) indicating the spectral intensity. The width of the wavelength is 400 nm to 720 nm.

This FIG. 2 shows plate temperatures of 20 ° C., 50 ° C. and 70 ° C.
3 shows the spectral intensity distribution by the reflectance (%) and the wavelength (nm) for the three plate temperatures of No.
m) A large difference occurs in the front and back positions. Here, the higher the plate temperature, the lower the reflectance.

FIG. 3 is a diagram showing an example of the relationship between the color of a red coated steel plate and the plate temperature, where the horizontal axis represents the plate temperature (° C.) and the vertical axis represents the difference in color from the standard color data. There is. The lightness L ^* and the chromaticities a ^* and b ^* are tristimulus values X and X based on the relationship between the reflectance and the wavelength in the spectral intensity distribution of the red coated steel sheet shown in FIG.
It is obtained by digitizing the color using a measuring method using Y and Z. Specifically, the lightness L ^* and the chromaticity a ^* and b ^* are
It is calculated by the following equations (1) to (3).

L ^* = 116 (Y / Yn) ¹ / 3−16 (1) a ^* = 500 [(X / Xn) ¹ / 3− (Y / Yn) ^1/3 ] (2) b ^* = 200 [(Y / Yn) ¹ / 3- (Z / Zn) ^1/3 ] (3) Here, X / Xn, Y / Yn, and Z / Zn are all 0.
Greater than 008856, Xn, Yn, and Zn are tristimulus values of a perfect diffusion surface under the same illumination as an object plane having tristimulus values of X, Y, and Z, and are normally standardized to Yn = 100.

The chromaticity a ^* and the chromaticity b ^* are divided into "+" and "-", respectively. As for the chromaticity a ^{*, the} larger the value on the “+” side, the greater the degree of red color, and the larger the value on the “−” side, the greater the degree of green color. Further, the larger the numerical value of the chromaticity b ^* on the “+” side, the greater the degree of yellow, and the larger the numerical value on the “−” side, the greater the degree of blue.

The lightness L ^* is whiter as the value is closer to 100, and is 0
The closer to, the blacker the color becomes. The total color difference ΔE ^* represents the difference between the color of the steel plate and the color of the reference value data. This is calculated by the formula (7) based on the values obtained by first obtaining the difference between the measured color value and the color setting value by the formulas (4) to (6).

ΔL ^* = L ^* measured value−L ^* set value (4) Δa ^* = a ^* measured value−a ^* set value (5) Δb ^* = b ^* measured value−b ^* set value (6) ) ΔE ^* = (Δa ^{* 2} + Δb ^{* 2} + ΔL ^{* 2} ) ^1/2 (7) In FIG. 3, the plate temperature of the red coated steel plate is 20
Δ when the plate temperature is changed using the case of ℃ as reference data
E ^* , Δa ^* , Δb ^* , and ΔL ^* are plotted. Code □
Is ΔL ^* , the symbol Δ is Δa ^* , the symbol ◇ is Δb ^* , and the symbol · is Δ
The state of E ^* is shown, and the higher the plate temperature, the larger the difference in color.

Therefore, in order to accurately measure the color value online, it is necessary to control the plate temperature during the color measurement within the range of the target set value (for example, 20 ° C. ± 5 ° C.) and measure the color. If the coated steel sheet is manufactured by controlling the color based on the color value that is simply measured without performing such an operation, there is a possibility that different evaluations will be made by the user when judging the color of the product. is there.

Next, the operation of the coated steel sheet manufacturing apparatus according to this embodiment will be described. In the manufacturing instruction file 23, as described above, the plate thickness of the steel plate, the plate width, the length, the coating film thickness setting value of the product, the allowable range of the coating film thickness, the dead zone setting value of the coating film, and the coating material to be applied. Type, color characteristics (relationship between coating thickness and color after baking), optimum baking maximum plate temperature and its dead zone setting value, color setting value of the painted surface of the product and its dead zone setting value, etc. are recorded. It is quantitatively expressed using the lightness L ^* , the chromaticity a ^* , and the chromaticity b ^* .

The steel plate 1a is fed from an uncoiler (not shown), and the paint is continuously applied by the coating device 2. Then, the steel sheet 1b coated with the coating material is heated in the baking oven 5 and the coating film is baked. The steel plate 1c having the coating film baked is cooled in the cooling zone 10 and wound on a coiler (not shown).

During this process, the maximum plate temperature for baking immediately after the baking furnace 5, the film thickness, color, and plate temperature of the colorimeter at the subsequent stage of the cooling zone 10 are the plate temperature meter 9, the film thickness meter 12, and the film thickness meter 12, respectively. Colorimeter 1
3. It is continuously measured by the color measuring plate thermometer 14.
These measured values are output to the comparison calculators 15 to 18, respectively.

The main computer 24 refers to the contents of the manufacturing instruction file 23 to refer to the respective comparison calculators 15 to 18 and the dead zone circuit 1.
Transfer necessary information to 9-22. That is, the plate thermometer 9
The optimum baking maximum plate temperature for the output calculator of the output stage, the dead zone set value of the maximum baking plate temperature for the dead zone circuit 19 of the output stage of the comparison calculator 15, the output calculator of the coating thickness gauge 12 1
6, the coating thickness setting value, the output stage dead zone circuit 20 of the comparison calculator 16 has a coating thickness dead zone setting value, and the output stage comparison calculator 17 of the colorimeter 13 has a color setting value, the comparison calculator 17 In the dead zone circuit 21 of the output stage, the color dead zone set value is set, in the comparison calculator 18 of the output stage of the color measuring plate thermometer 14, the plate temperature set value of the color meter section is set, and in the dead zone circuit 22 of the comparison calculator 18, the color is set. The dead zone set values of the instrument plate temperature are transmitted respectively.

Main computer 24 through dead zone circuits 19-22
The main computer 24 sends control commands to the coating film thickness controller 25, the fuel valve opening controller 26, the hot air flow controller 27, and the water flow controller 28 in accordance with the data returned to the controller, and the proper command is sent based on these control commands. Control is performed.

FIG. 4 is a flow chart showing the arithmetic processing in the main computer 24. When the measured maximum seizure plate temperature exceeds the dead zone set value and has a difference from the optimum maximum seizure plate temperature, the main computer 24 issues a command to adjust the fuel valve opening and the hot air flow rate, respectively. , To the hot air flow controller 27 (s1). That is, when the maximum seizure plate temperature is high, the output that the fuel valve opening is closed is output, and the output that the amount of hot air is reduced is output (s2). Further, when the maximum baking plate temperature is low, the fact that the fuel valve opening degree is open is output, and the fact that the hot air amount is increased is output (s3).

Similarly, when the calculated coating film thickness exceeds the dead zone setting value and has a difference from the coating film thickness setting value, the main computer 24 issues an instruction to the coating film thickness controller 25 to adjust the roll gap amount. Output (s4). That is, when the coating film thickness is thick, the output that the coating amount of the coating material is decreased is output (s5), and when the coating film thickness is thin, the output that the coating amount of the coating material is increased is output (s6).

Further, when the measured value of the plate temperature of the colorimeter section exceeds the dead zone set value and has a difference from the appropriate colorimeter section plate temperature set value, the main computer 24 issues an instruction to adjust the amount of water in the cooling zone 10. It outputs to the water quantity controller 28 (s7). That is, when the plate temperature of the colorimeter is low, it outputs that the water flow control valve 11 is closed (s8), and when the plate temperature of the colorimeter is high, it outputs that the water flow control valve 11 is opened (s9). ).

Then, the main computer 24 inputs the information on the lightness L ^* , the chromaticity a ^* , and the b ^* concerning the color from the colorimeter 13 through the comparison calculator 17 and the dead zone circuit 21, and measures the respective values. , It is determined whether or not this measured value is appropriate (s1
0).

As shown in the example of coating film thickness-color characteristics of FIG. 5 and the example of plate temperature-color characteristics of FIG. 6, there is a close relationship between color and coating film thickness and between color and plate temperature. By adjusting the coating film thickness and the plate temperature within the allowable range, the color can be brought into an appropriate state. In FIG. 5, the allowable range is between the plate temperature d and the plate temperature e, and in FIG. 6, the allowable range is between the coating thickness f and the coating thickness g.

From the relationships shown in FIGS. 5 and 6, the measured value of the colorimeter 13 is compared with the respective set value by the comparison calculator 17 at the output stage. If the color is not appropriate, Δa ^* , which indicates the control deviation,
A check of Δb ^* and ΔL ^* is performed. Δa ^* , Δb ^* , Δ
When L ^* is smaller than the dead zone set value, the dead zone circuit 21
The output signal from is 0.

Checking Δa ^* (s11), checking Δb ^* (s12a, s12b), checking ΔL ^* (s1)
3a, s13b), when Δa ^* , Δb ^* , and ΔL ^* are all 0 or more, the main computer 24 decreases the coating film thickness setting value within a predetermined changeable range of the coating film thickness setting value. An instruction to change is output to the coating film thickness controller 25 (s14). If Δa ^* , Δb ^* , and ΔL ^* are all less than 0, the main computer 24 gives an instruction to make a large change in the coating film thickness setting value within a predetermined changeable range of the coating film thickness setting value. It is output to the coating film thickness controller 25 (s15).

Further, it is judged whether the color has become proper only by changing the set value of the coating film (s16a, s16b), and if not, the Δa ^* is checked again (s1).
7), Δb ^* check (s18a, s18b), ΔL ^*
Check (s19a, s19b), Δa ^* ,
When Δb ^* and ΔL ^* are all 0 or more, the main computer 24
Outputs to the fuel valve opening controller 26 and the hot air flow controller 27 an instruction to increase the maximum seizure plate temperature set value within a predetermined changeable range of the maximum seizure plate temperature set value (s
20). When Δa ^* , Δb ^* , and ΔL ^* are all less than 0, the main computer 24 lowers the maximum seizure plate temperature set value within a predetermined changeable range of the maximum seizure maximum plate temperature set value. The instruction is output to the fuel valve opening controller 26 and the hot air flow controller 27 (s21), and it is determined whether the color has become appropriate (s22a, s22b).

If the coating thickness cannot be changed because it exceeds one of the upper and lower limits of the changeable range, the maximum baking temperature cannot be changed because it exceeds one of the upper and lower limits of the changeable range, Δa If the change in coating film thickness cannot be judged from the positive / negative of ^* , Δb ^* , and ΔL ^* , or if the maximum baking plate temperature cannot be changed, the steel sheet on which the coating film is formed is marked as “abnormal in color”. It is recognized and recorded (s23), and this information is used as information at the time of using and shipping the coated steel sheet.

Finally, it is determined whether or not to continue the processing (s24), and if the processing is to be continued, the same processing is repeated. As described above, in the coated steel plate manufacturing apparatus according to the present embodiment, the cooling zone 10 sets the plate temperature of the steel plate 1c at the time of color measurement within the target setting range suitable for color measurement, and then the color is measured by the colorimeter 13. Because of the measurement, the color measurement is performed well.

Then, the main computer 24 changes the set value of at least one of the coating film thickness and the maximum baking temperature within each changeable range on the basis of the measured color value to properly control the color of the steel sheet 1. Therefore, it is possible to always manufacture a coated steel sheet with a stable color.

In the present embodiment, the plate thermometer 9 for measuring the maximum plate temperature for baking is installed at the subsequent stage of the baking furnace 5.
The installation position of the plate thermometer 9 is not limited to this, and the plate thermometer 9 may be provided at the rear of the baking furnace 5. Also,
The plate thermometer 9, the comparison calculator 15, and the dead zone circuit 19 may be removed by appropriately maintaining the amount of the combustion gas blown into the baking furnace 5.

Further, although the coating film thickness meter 12 is installed in the latter stage of the cooling zone 10, the invention is not limited to this, and it may be installed in another position. Further, the plate thermometer 9 and the color measuring plate thermometer 14 are not limited to the non-contact type radiation thermometer, but also the contact type radiation thermometer, and further, the temperature of the traveling object disclosed in JP-A-8-101079. Various devices such as measuring devices to which the measuring method is applied can be used.

Further, although it has been shown that an infrared coating film thickness meter can be used as the coating film thickness meter 12, the invention is not limited to this, and various ones can be used. In addition, the coating film thickness meter 1
2. It is also possible to remove the comparison calculator 16 and the dead zone circuit 20, and to control the coating thickness and the maximum baking plate temperature to stabilize the color only by the measurement results by the color meter 13 and the color measuring plate thermometer 14. .

[0054]

As described above, the apparatus and method for manufacturing a coated steel sheet according to the present invention is a method for coating a steel sheet on which a coating means having a coating film thickness control function for forming a coating film of a specified thickness travels. The baking means having the baking temperature control function in the latter stage of the coating means bake the surface temperature of the steel sheet at a specified temperature, and the cooling means having the cooling control function in the latter stage of the baking means controls the cooling state of the steel sheet. While cooling, the color measuring means after the cooling means measures the color of the steel plate, the plate temperature measuring means near the measurement position by the color measuring means measures the surface temperature of the steel plate, and the plate of the measurement result by the plate temperature measuring means The cooling control function of the cooling means controls the cooling state of the steel sheet based on the temperature signal value, and based on the color signal value of the color measuring means obtained in this state, the control target value of the coating film thickness control function of the coating means or baking. Means baking temperature It is to change at least one of the control target value of the control function.

Therefore, the cooling means brings the surface temperature of the steel sheet during the color measurement into the target setting range suitable for the color measurement, and thereafter the color is measured by the color measuring means, so that the color measurement is favorably performed.

Further, based on the result of the color measurement, the baking temperature control function of the baking means controls the surface temperature of the steel sheet so that the color is in a predetermined state, and the coating film thickness control function of the coating means controls the coating temperature. Since the thickness of the film is controlled, it is possible to always manufacture a coated steel sheet with a stable color.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration example of a coated steel sheet manufacturing apparatus adopting a coated steel sheet manufacturing method according to an embodiment of the present invention.

FIG. 2 is a diagram showing an example of a spectral intensity distribution of a red coated steel sheet.

FIG. 3 is a diagram showing an example of a relationship between a color difference of a red-painted steel plate and a plate temperature.

FIG. 4 is a flowchart showing a calculation process in the main computer of the same embodiment.

FIG. 5 is a diagram showing an example of coating film thickness-color characteristics.

FIG. 6 is a diagram showing an example of plate temperature-color characteristics.

[Explanation of symbols]

1a, 1b, 1c ... Steel plate 2 ... Coating equipment 2a ... Pickup roll 2b ... Applicator roll 2c ... Backup roll 3 ... Paint pan 4 ... Roll gap adjusting device 5 ... Baking furnace 6 ... Fuel control valve 7. Hot air blower 8 ... Motor 9, 14 ... Plate thermometer 10 ... Cooling zone 11 ... Water flow control valve 12 ... Coating film thickness meter 13 ... Colorimeter 15-18 ... Comparison calculator 19 to 22 ... Dead band circuit 23 ... Manufacturing instruction file 24 ... Main computer 25 ... Coating film thickness controller 26 ... Fuel valve opening regulator 27 ... Hot air flow controller 28 ... Water flow controller

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁷ identification code FI B05D 7/14 B05D 7/14 Z (58) Fields investigated (Int.Cl. ⁷ , DB name) B05C ⁷ /00-21 / 00 B05D 1/00-7/26

Claims (2)

(57) [Claims] 1. A coated steel sheet manufacturing apparatus for manufacturing a coated steel sheet by continuously applying a coating material to a traveling steel sheet, having a coating film thickness control function, and applying a coating material to the traveling steel sheet to obtain a steel sheet. Coating means for forming a coating film of the above-specified thickness, and provided at the latter stage of the coating means, having a baking temperature control function, controlling the surface temperature of the steel sheet to a designated temperature, and applying the coating. Baking means for baking the paint on a steel plate, and having a cooling control function provided in the latter stage of the baking means,
Cooling means for cooling the steel plate on which the paint has been baked to a specified cooling state, color measuring means provided in the subsequent stage of the cooling means for measuring the color of the cooled steel sheet, and color by the color measuring means. And a plate temperature measuring means for measuring the surface temperature of the steel plate in the vicinity of the measurement position, and the cooling control function of the cooling means cools the steel plate based on the plate temperature signal value of the measurement result by the plate temperature measuring means. The state is controlled, and at least one of the control target value of the coating thickness control function of the coating means or the control target value of the baking temperature control function of the baking means is changed based on the color signal value of the measurement result by the color measuring means. An apparatus for manufacturing a coated steel sheet, which is characterized by: 2. A method for producing a coated steel sheet, wherein a coating material is continuously applied to a running steel sheet to produce a coated steel sheet, wherein a coating means having a coating film thickness control function for forming a coating film having a designated thickness is provided. A paint is applied to the running steel plate, and a baking means having a baking temperature control function for controlling the surface temperature of the steel plate after the paint is applied to a specified temperature bakes the paint to the steel plate, and the paint is baked. The cooling means having a cooling control function for controlling the cooling state of the steel sheet after being cooled cools the steel sheet, the color of the steel sheet after being cooled is measured by a color measuring means, and the color is measured by the color measuring means. The plate temperature measuring means provided near the position measures the surface temperature of the steel plate near the color measurement position, and based on the plate temperature signal value of the measurement result by the plate temperature measuring means, a cooling control function of the cooling means. Is the steel Control the cooling state of the plate, based on the color signal value of the measurement result by the color measuring means, the control target value of the coating film thickness control function of the coating means or the control target of the baking temperature control function of the baking means. A method for producing a coated steel sheet, characterized in that at least one of the values is changed.