JPH10239156A - Color measuring equipment for painted steel plate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an equipment for measuring the color of a painted steel plate accurately. SOLUTION: The color measuring equipment 4 is built in a line for continuously painting a steel plate 1 being transferred, in order to measure the color of a painted steel plate after baking. The color measuring equipment 4 comprises means 11 for detecting the color of a painted steel plate, means 12 for measuring the surface temperature of a painted steel plate in the vicinity of a position where the color is measured by the color detecting means 11, and means 7 disposed in the prestage of the color detecting means 11 and the plate temperature measuring means 12 and controlling the surface temperature of a painted steel plate based on a plate temperature signal value representative of the measurement of the plate temperature measuring means 12.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for measuring the color of a coated steel sheet, which is one of the control elements of the baking control in a continuous coating line.

[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, and the coating film of the coated steel sheets has the required thickness, color, workability and scratch resistance for each use of the coated steel sheets. It is required to have a function.

[0003] Generally, the production of a coated steel sheet is carried out by continuously running the steel sheet on a line provided with a coating apparatus, a baking furnace and the like. That is, the steel plate is first coated with a paint by a coating device and then baked in a baking furnace. In addition, a film thickness detector, a colorimeter, a sheet temperature meter for measuring the surface temperature of the steel sheet (hereinafter referred to as the sheet temperature) and the like are arranged on this online, and control of the film thickness and the color are performed. I have.

Japanese Patent Application Laid-Open No. 63-7870 discloses a method for detecting the surface temperature, thickness and color of a steel sheet having a coating film formed on the exit side of a baking furnace, and detecting the highest baking sheet of the detected steel sheet. There is disclosed a coating film control device that performs a feedback control to adjust a furnace temperature based on a temperature and to adjust a coating amount based on a detected coating thickness and a color of a coating surface.

Japanese Patent Application Laid-Open No. 2-222750 discloses that a coating thickness is controlled by a coating thickness meter that measures the coating thickness from the weight of a supplied coating material, and a colorimeter installed downstream of the drying and baking process. A color difference signal is detected by the meter, and based on a management standard for each paint color separately prepared according to the detected color difference signal,
A control method for changing a control target value of a coating film thickness or a baking temperature is disclosed.

[0006]

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

[0007] This variation in color is measured without considering the temperature of the steel sheet at the time of online color measurement. Therefore, accurate color measurement is not performed, and based on the measurement result. This is due to the production of painted steel sheets by performing color control.

As described above, since the conventional color measuring apparatus for painted steel sheet measures without considering the sheet temperature of the steel sheet at the time of color measurement, accurate color measurement may not be performed.
Therefore, when a coated steel sheet is manufactured using the result obtained by the conventional color measuring apparatus for a coated steel sheet, there is a problem that the color of the product of the coated steel sheet fluctuates.

The present invention has been made in view of the above circumstances, and provides a color measuring apparatus for a coated steel sheet for accurately measuring the color of a coated steel sheet, which is one control element of a coating baking control, in a continuous coating line. The purpose is to do.

[0010]

SUMMARY OF THE INVENTION In order to solve the above problems, the present invention is applied to a continuous coating line for coating a steel sheet to be conveyed, and measures the color of the coated steel sheet after baking. In the measuring device, a color detecting means for detecting the color of the coated steel sheet, a sheet temperature measuring means for measuring the surface temperature of the coated steel sheet near the position where the color is detected by the color detecting means, and a color detecting means and a sheet temperature measuring means. A color measuring apparatus for a coated steel sheet, comprising: a sheet temperature control means installed in a preceding stage and controlling a surface temperature of the coated steel sheet based on a sheet temperature signal value measured by the sheet temperature measuring means.

Therefore, in the color measuring apparatus for a coated steel sheet according to the present invention, the sheet temperature control means sets the surface temperature of the coated steel sheet suitable for color detection based on the sheet temperature signal value measured by the sheet temperature measuring means. , Accurate color measurement is possible.

[0012]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a schematic configuration diagram of a continuous coating line in which the color measuring device of the present embodiment is incorporated.

A coating device 2, a baking furnace 3, and a color measuring device 4 are installed along the transport path of the steel sheets 1 (1a, 1b, 1c). A coating apparatus 2 for applying a paint to a steel plate 1a includes a pickup roll 2a, an applicator roll 2b, and a backup roll 2c.
a and the applicator roll 2b are each rotationally driven by a motor (not shown). The pickup roll 2a picks up paint from the paint pan 5 and supplies the paint to the applicator roll 2b. The applicator roll 2b causes the paint to adhere to the contacting steel plate 1a.

The pickup roll 2a and the applicator roll 2b are provided with a roll gap adjusting device including a servomotor and a screw mechanism (not shown).
The amount of paint applied is controlled by the gap between the rolls.

A baking furnace 3 is arranged on the outlet side of the coating apparatus 2. The baking furnace 3 heats and bake the coated steel plate 1b by supplying hot air gas obtained by burning the fuel gas. The amount of fuel gas is adjusted by the opening of a fuel control valve (not shown), and the amount of hot air is adjusted by the rotation speed of a motor driving a hot air blower (not shown). That is, by controlling the opening degree of the fuel control valve and the rotation speed of the motor, the maximum plate temperature of seizing is controlled.

Immediately after the baking furnace 3, there is provided a sheet thermometer 6 for detecting the maximum sheet temperature of the steel sheet 1c having the coating film formed thereon. As the plate thermometer 6, for example, a non-contact radiation thermometer can be used.

At the subsequent stage of the plate thermometer 6, there is provided a plate temperature control device 7 of the color measuring device 4 according to the present embodiment, and the opening of the water amount control valve 8 or the opening of the hot air control valve 9 controls the steel plate 1c. Control the sheet temperature. Further, a coating film thickness gauge 10 is provided on the subsequent stage.

A color measuring device 4 is provided after the coating film thickness meter 10.
Colorimeter 11 and a colorimetric plate thermometer 12 are installed. The color measuring device 4 is provided in a continuous coating line for manufacturing a coated steel plate, and measures the color of the coated steel plate, which is one control element of coating baking control.

The colorimeter 11 detects the color of the coated steel plate. In the vicinity of the measurement position of the colorimeter 11 (hereinafter referred to as a colorimeter section), a colorimetric plate thermometer 12 for measuring the plate temperature is provided. For example, a non-contact radiation thermometer can be used as the color measurement plate thermometer 12, similarly to the plate thermometer 6 described above.

The colorimeter 11 and the color temperature measuring thermometer 12 have comparison computing units 13 and 14 and dead zone circuits 15 and 1, respectively.
6 are connected. Dead zone circuits 15 and 16 prevent hunting of the control system.

The main computer 17 calculates the plate temperature of the colorimeter section based on the information in the manufacturing instruction file 18 and the signals from the colorimeter 11 and the colorimeter plate thermometer 12 and calculates the water temperature controller 19 or Output to the hot air regulator 20 respectively. The water volume controller 19 and the hot air volume controller 20 output adjustment signals to the water volume control valve 8 and the hot air volume control valve 9, respectively, and the opening degrees of the water volume control valve 8 and the hot air volume control valve 9 change based on the control signals.

Thus, the amount of water and the amount of hot air supplied to the plate temperature control device 7 change, and the plate temperature of the steel plate 1c is controlled.
As described above, in the coated steel plate color control device 4 according to the present embodiment, the plate temperature of the steel plate 1c passing through the plate temperature control device 7 is feedback-controlled, and the plate temperature at the time of color measurement is always set to an appropriate target for measurement. Since the color of the steel sheet 1c can be measured within the range of the set value, accurate color measurement can be performed, thereby preventing color fluctuation of the product of the coated steel sheet.

In this embodiment, the plate temperature of the steel plate 1c is controlled by the amount of water and the amount of hot air supplied to the plate temperature control device 7, but the baking furnace 3 is provided in front of the plate temperature control device 7. Since the steel plate 1c is baked by this and sent to the plate temperature control device 7 in a high temperature state, the hot air control valve 9 and the hot air control device 20 are removed, and the water flow according to the control signal from the water control device 19 is removed. The sheet temperature of the steel sheet 1c can be feedback-controlled only by opening and closing the control valve 8.

Further, a plate thermometer 6 for measuring the maximum plate temperature of the baking is installed at the subsequent stage of the baking furnace 3, but the installation position of the plate thermometer 6 is not limited to this. Baking furnace 3
May be provided at the rear. Further, the sheet thermometer 6 may be removed by appropriately maintaining the amount of combustion gas blown into the baking furnace 3.

Further, the coating film thickness gauge 10 is installed at the subsequent stage of the plate temperature controller 7, but is not limited to this, and may be installed at another position. In addition, the plate thermometer 6 and the color thermometer 12
In addition to non-contact radiation thermometers, various devices such as contact radiation thermometers and measuring devices to which the temperature measurement method of a traveling object disclosed in Japanese Patent Application Laid-Open No. H8-10179 is applied are used. it can.

[0026]

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

FIG. 2 shows the sheet temperatures of 20 ° C., 50 ° C. and 70 ° C.
3 shows the spectral intensity distribution according to the reflectance (%) and the wavelength (nm) for the three types of plate temperatures, and the wavelength is 600 (n).
m) There is a large difference between the front and rear 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 the red painted steel sheet and the sheet temperature. The horizontal axis indicates the sheet temperature (° C.), and the vertical axis indicates the difference in color from the standard color data. I have. The lightness L ^* , chromaticity a ^* and b ^* are based on the relationship between the reflectance and the wavelength in the spectral intensity distribution of the red painted steel sheet shown in FIG.
It is obtained by numerically expressing colors using a measurement method based on Y and Z. Specifically, the lightness L ^* , 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.
Xn, Yn and Zn are larger than 008856, and are tristimulus values of a perfect diffusion surface under the same illumination as the object surface having tristimulus values X, Y and Z, and are usually standardized to Yn = 100.

The chromaticity a ^* and the chromaticity b ^* are respectively divided into "+" and "-". As for the chromaticity a ^*, the degree of redness increases as the numerical value increases on the “+” side, and the degree of greenness increases as the numerical value increases on the “−” side. The degree of yellow is larger as the numerical value of the chromaticity b ^* is larger on the “+” side, and the degree of blue is larger as the numerical value is larger on the “−” side.

The lightness L ^* is such that the closer the value is to 100, the whiter,
The closer to, the more black. The total color difference ΔE ^* indicates a difference between the color of the steel sheet and the color of the reference value data. First, the difference between the actually measured color value and the color setting value is obtained by the equations (4) to (6), and the difference is calculated by the equation (7) based on the obtained value.

ΔL ^* = L ^* actual value−L ^* set value (4) Δa ^* = a ^* actual value−a ^* set value (5) Δb ^* = b ^* actual value−b ^* set value (6) ) ΔE ^* = (Δa ^{* 2} + Δb ^{* 2} + ΔL ^{* 2} ) ^1/2 (7) In FIG.
Δ when plate temperature is changed with reference to ° C
E ^* , Δa ^* , Δb ^* , ΔL ^* are plotted. Sign □
Is ΔL ^* , sign △ is Δa ^* , sign ◇ is Δb ^* , sign · is Δ
It shows the state of E ^* , which indicates that the higher the plate temperature, the larger the color difference.

Therefore, in order to accurately measure the color value on-line, the color temperature is controlled by controlling the plate temperature at the time of the color measurement within the range of the target set value (for example, 20 ° C. ± 5 ° C.). It is necessary to convert the obtained color value into a color value at the time of the reference plate temperature. Without doing this,
If the coated steel sheet is manufactured by controlling the color based on the simply measured color value, there is a possibility that the user or the like may make a different evaluation when determining the color of the product.

In the color measuring device 4 for painted steel plates shown in FIG. 1, in such a case, the plate temperature adjusting device 7 controls the plate temperature to be within the range of the target set value (for example, 20 ° C. ± 5 ° C.). Therefore, normal color measurement is possible.

[0035]

As described above, according to the color measuring apparatus for a coated steel sheet provided in the continuous coating line according to the present invention, the color detecting means detects the color of the coated steel sheet, and the color detecting means detects the color. Sheet temperature measuring means installed in the vicinity measures the surface temperature of the coated steel sheet, and sheet temperature control means installed in front of the color detection means and the sheet temperature measuring means sets the sheet temperature signal value of the measurement result by the sheet temperature measuring means. Since the surface temperature of the coated steel sheet is controlled based on the above, accurate color measurement can be performed without being affected by the state of the surface temperature of the coated steel sheet. In addition, it is possible to prevent the color of the product of the coated steel plate from changing.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a schematic configuration example of a continuous coating line in which a color measuring device for a coated steel sheet according to an embodiment of the present invention is incorporated.

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

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

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 (1a-1c) ... Steel plate 2 ... Coating device 2a ... Pickup roll 2b ... Applicator roll 2c ... Backup roll 3 ... Baking furnace 4 ... Color measuring device 5 ... Paint pan 6 ... Sheet thermometer 7 ... Sheet temperature control device 8 ... Water control valve 9 ... Hot air control valve 10 ... Coating film thickness gauge 11 ... Color meter 12 ... Color measuring plate thermometer 13,14 ... Comparison calculator 15,16 ... Bad zone circuit 17 ... Main computer 18 ... Manufacturing instruction file 19 … Water volume controller 20… Hot air regulator

Claims (1)

[Claims] An apparatus for measuring the color of a coated steel sheet which is incorporated in a continuous coating line for coating a steel sheet to be conveyed and which measures the color of the coated steel sheet after baking, comprising: a color detecting means for detecting a color of the coated steel sheet; A sheet temperature measuring means for measuring a surface temperature of the coated steel sheet in the vicinity of a position at which a color is detected by the color detecting means; and a color temperature detecting means installed before the color detecting means and the sheet temperature measuring means. A sheet temperature control unit for controlling a surface temperature of the coated steel sheet based on a sheet temperature signal value of the measurement result.