JPH09192591A - Coating amount measuring method and coating film thickness measuring method - Google Patents

Abstract

(57) Abstract: It is an object to measure a coating film thickness capable of improving the accuracy of film thickness control while shortening the coating time measurement time interval while ensuring a predetermined measurement accuracy. SOLUTION: When a paint in a paint tank is continuously applied to a continuously fed steel strip, the paint weight in a paint tank communicating with the paint tank is sampled at a predetermined sampling time, and A coating amount measuring method for obtaining a coating amount on the steel strip from the sampled paint weight, wherein a predetermined number of samplings n (= 8) for each sampling time Δt.
While obtaining the unit average value Di, the application amount is obtained based on the difference between the average value Di and the average value Di ₊₄ obtained when the average value Di is deviated by a predetermined time interval (Δt · m) from the time when the average value was measured. .

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for measuring a coating amount and a coating film thickness when a coating material is continuously coated on a sheet-shaped continuous body such as a steel strip.

[0002]

2. Description of the Related Art Conventionally, an apparatus using a roll coater has been known as an apparatus for controlling a coating amount while continuously applying a coating material to a continuously fed steel strip. The coating device using this roll coater transfers the paint in the paint tank to the surface of the steel strip with a rotating pick-up roll to apply the paint continuously to the surface of the steel strip that is continuously fed. To do.

At this time, it is desirable that the coating film applied to the steel strip has a uniform target film thickness. Therefore, conventionally, the coating amount applied to the steel strip is measured so that the coating film thickness becomes the target film thickness, and the coating film thickness is controlled by controlling the coating amount or the coating film thickness applied. It controls the coating amount on the steel strip based on the thickness. As a conventional method for measuring the coating amount in order to control the coating film thickness, there is one described in, for example, JP-A-61-230767.

As shown in FIG. 4, this coating amount measuring method is provided with a paint tank 51 which communicates with the paint tank 50, circulates the paint between the paint tank 51 and the paint tank 50, and In an apparatus configuration in which the amount of paint in 50 is constant, the weight of the paint tank 51 is set to the load cell 52.
The weight of the paint in the paint tank 51 is sampled at every predetermined sampling time Δt, and the average value Ai of the predetermined sampling number n of this sampling data is calculated as shown in FIG. 5A. Is repeated by shifting the sampling number by n or less by a predetermined sampling number. In FIG. 5, the number of samplings n for obtaining the average value Ai is eight, and the predetermined number of samplings m to be shifted is four. Further, X = m · Δt.

Then, two average values A continuously obtained
i, Ai ₋₁ , the consumption amount of the coating amount is sequentially obtained, and the coating amount applied to the steel strip 55 is calculated from the consumption amount of the coating material and the feed rate and plate width of the steel strip 55 at that time. To do. This is based on the fact that the amount of paint in the paint tank 50 is adjusted to a constant amount, and therefore the amount of decrease in the paint in the paint tank 51 becomes the amount applied to the steel strip 55, but the weight change thereof. Varies with various error factors and decreases.
Therefore, the averaging calculation as described above is performed in order to average the minute fluctuations and obtain the amount of the paint in the paint tank 50 with a measurement accuracy of a predetermined value or more.

Here, as another conventional averaging operation, as shown in (c) of FIG. 5, an average value Ci is calculated for every n units of a predetermined sampling number, and two consecutive average values Ci, There is also a method of obtaining the consumption amount of the above coating amount from Ci ₋₁ . In this averaging calculation method, if the number of samplings n for obtaining one average value Ci is increased, the above average value Ci
Although the accuracy of the value of is improved, the time interval for obtaining the average value Ci, and further the time interval for obtaining the consumption amount of the coating amount are extended, and the quick response of the control operation is reduced.

In view of this, in the above-described averaging calculation method, the calculation of the average value Ai is performed by shifting the sampling number n or less by a predetermined number of samplings by m, whereby the time interval for obtaining the average value Ai, Further, the time interval for calculating the consumption amount of the coating amount is calculated in the time unit X (= Δt · m) corresponding to the shifted sampling number m. As a result, the responsiveness of the control operation is improved while ensuring a predetermined measurement accuracy.

A conventional method for controlling the coating film thickness by measuring the coating film thickness is, for example, Japanese Patent Publication No. 63-4.
Some are disclosed in Japanese Patent No. 5863. In this conventional method, the actual coating film on the steel strip 55 coated with a roll coater is measured with a coating film thickness meter (54 in FIG. 4),
Based on the deviation between the measured coating film thickness measured by the thickness gauge 54 and the target coating film thickness, the pressing force and rotational force of the roll of the roll coater 56 are controlled so that the steel strip 55 is removed from the coating tank 50.
The coating amount is adjusted to control the coating amount to be a target value.

[0009]

However, in the conventional method for measuring the coating amount as described above, the average value A
The consumption amount of the coating amount, that is, the coating amount can be measured only at the time interval Δt · m corresponding to the sampling number m shifted to obtain i, and the measurement can be performed while ensuring a predetermined measurement accuracy. The time interval Δt · m cannot be shortened. As a result, there is a problem that there is a limit in improving the quick response of the control operation.

That is, in order to shorten the coating amount measuring time, if the sampling number m to be shifted to obtain the average value Ai is set to 1 sampling, as shown in FIG. Although the coating amount can be measured in units, the difference between two consecutive average values is, for example, considering the difference between the average values of B1 and B2 in FIG. 5, the sampling data at sampling times t1 and t2. However, since the data at each time t1 and t2 is raw sampling data that has not been averaged together, the variation in the difference is about the same as the variation in the sampling data itself, and the sampling number n is increased. However, the accuracy of the average value Bi is not stable. As described above, in the conventional coating amount measuring method, the measuring time interval Δ of the coating amount is
If tm is shortened, the accuracy of the average value Ai becomes worse.

The coating film thickness applied to the steel sheet varies depending on the fluctuation of the solid content concentration of the coating material. Therefore, when the coating film thickness is controlled only by the measured coating amount, the coating film thickness after drying may vary by the fixed component concentration fluctuation. Next, in the conventional coating film thickness measuring method described in Japanese Patent Publication No. 63-45863, the coating film thickness on the steel strip 55 coated in practice is measured. When the coating film thickness is controlled using the film thickness, there is a large dead time between the coating by the coater roll 56 and the detection of the film thickness by the thickness meter 54,
The film thickness control may not be stable for a predetermined time from the start of coating on the target steel strip 55.

Further, since the coating film thickness is in an undried state before being dried in the drying oven 57, there is a possibility that the coating film thickness may vary by the variation of the fixed concentration. The present invention has been made by paying attention to the problems as described above, and it is possible to improve the accuracy of film thickness control while shortening the coating time measurement time interval while ensuring a predetermined measurement accuracy. The challenge is to measure.

[0013]

In order to solve the above problems, in the coating amount measuring method of the present invention, the paint in the paint tank is continuously applied to the continuously fed sheet-like continuous body. At this time, by a coating amount measuring method in which the weight of the paint in the paint tank or a paint container communicating with the paint tank is sampled at predetermined sampling times, and the amount of the paint applied to the sheet-like continuous body is measured from the sampled paint weight. Therefore, while obtaining the average value of the predetermined sampling number unit for each sampling time, the average value and the average value obtained when the average value is deviated by a predetermined time interval different from the sampling time from the time of measuring the average value. The feature is that the coating amount is measured based on the difference.

Here, the predetermined time interval different from the sampling time is a time interval larger than the sampling time, and is a time interval sufficient for the measurement accuracy of the coating amount to be within the allowable range. In the present invention, the average value of the predetermined number of samplings is calculated in units of sampling time, and the coating amount is calculated based on the difference between the average value shifted by the predetermined time interval. Even if the sampling time is shortened, the same measurement accuracy as the conventional one can be secured.

Here, the measurement accuracy by the averaging calculation will be supplemented. In the following description, the weight of the sampled paint is Wi, the sampling time is Δt, and the number of samples is n. For example, for comparison, the consumption amount T ′ of the paint when averaging is not performed is expressed by the following equation.

[0016]

[Equation 1]

On the other hand, the consumption amount T of the paint when the averaging calculation used in the present invention is used is expressed by the following equation. The time interval for shifting is set to Δt × m.

[0018]

[Equation 2]

Comparing T'and T in the above two equations,
By using the present invention, it can be seen that the measurement error is (1 / m) as compared with the case where averaging is not performed. Next, in the coating film thickness measuring method according to claim 2, a coating film is obtained from the coating amount obtained by the coating amount measuring method according to claim 1 and the solid content concentration of the coating material obtained from the viscosity and temperature of the coating material. It is characterized by measuring the thickness.

In the present invention, in addition to the effect of the first aspect, the coating thickness after drying is determined by the coating amount before coating and the solid content concentration of the coating material remaining after drying.

[0021]

Next, embodiments of the present invention will be described with reference to the drawings. First, the structure will be described. As shown in FIG. 1, a part of the pickup roll 1a of the coater roll 1 is in a state of being immersed in the paint in the paint tank 2. By rotating the pickup roll 1a, the coating material wound up by the pickup roll 1a is continuously transferred and applied to the steel strip 7 which is a sheet-like continuous body sequentially fed. 1b
Is a backup roll.

A weir 3 is provided in the paint tank 2 so that the amount of paint that exceeds the height of the weir 3 overflows from the weir 3 and returns to the paint tank 4 which is a paint container. There is. Further, the paint tank 2 and the paint tank 4 are provided with a supply pipe 5.
The paint in the paint tank 4 is supplied to the paint tank 2 by a pump 6. Supply to the paint tank 2 is performed from the paint tank 2 to the steel strip 7
By setting a larger amount than the amount applied to the paint tank 2, a part of the paint in the paint tank 2 always overflows and the overflowed paint returns to the paint tank 4. The amount of is adjusted to be a constant amount.

Further, a paint supply pipe 8 is provided in the paint tank 4.
One end of the paint tank is connected and a shutoff valve 9 inserted in the middle of the paint supply pipe 8 is operated to supply new paint into the paint tank 4. The shutoff valve 9 is opened / closed by an opening / closing command from the coating amount calculator 10.
In addition, the paint tank 4 includes a load cell 11 such as a load cell.
Is provided, and the weight of the paint tank 4 can be measured by the load meter 11. The load meter 11 can supply the measured load signal to the coating amount calculator 10.

Further, a thermometer 12 and a viscometer 1 are provided in the middle of a supply pipe 5 which connects the paint tank 4 and the paint tank 2 to each other.
3 is inserted, and the temperature and viscosity of the paint flowing in the supply pipe 5 are measured. Then, signals corresponding to the temperature and the viscosity measured by the thermometer 12 and the viscometer 13 can be supplied to the film thickness calculator 14, respectively. Also,
The length meter 15 comes into contact with the steel strip 7 to be sent, the feed amount of the steel strip 7 is measured by the length gauge 15, and a signal L corresponding to the feed amount is supplied to the coating amount calculator 10. It is possible.

The coating amount calculator 10 calculates the weight of the paint in the paint tank 4 based on the load signal supplied from the load meter 11, and when the calculated amount of the paint is less than or equal to the set lower limit value, the cutoff is performed. It is possible to supply an opening command to the valve 9 and supply a closing command to the shut-off valve 9 when the paint in the paint tank 4 has been replenished to the set upper limit value or more. Further, the coating amount T calculator 10 is supplied with the plate width b of the steel strip 7 from the plate width gauge 16 or the like. Then, the coating amount T calculator 10 has the plate width b.
Alternatively, the application amount T per unit of the steel strip 7 is obtained and obtained based on the load signal supplied in the unit of the predetermined sampling time Δt and the feed amount L of the steel strip 7 supplied from the length meter 15. The coating amount T can be supplied to the film thickness calculator 14.

Next, the calculation of the coating amount T will be described with reference to FIG. The paint weight Wi at the current sampling time ti is calculated based on the load signal supplied from the load meter 11 in units of sampling time Δt, and the paint weight Wi is sequentially stored, and the current value is calculated based on the following equation for each sampling time Δt. From the sampling time, the average value is obtained from the paint weight Wi for a predetermined number of samples and sequentially stored. Here, FIG. 2 exemplifies a case where the predetermined sampling number n is eight.

[0027]

(Equation 3)

Further, as in the following equation, the difference between the average value Di obtained at the current sampling time and the average value Di obtained a predetermined time (Δt × m) before that time is obtained, and the difference is calculated. By dividing by the above predetermined time (Δt × m), the amount E of decrease in the paint per unit time is calculated. Here, in FIG. 2, a case where the above-mentioned m is 4 is illustrated.

[0029]

(Equation 4)

Further, as shown in the following equation, the area S (= L × b) of the steel plate 7 applied from the feed amount L and the plate width b applied based on the signals from the length meter 15 and the plate width meter 16 described above. ) Is obtained and the reduction amount E calculated above is divided by the area S to obtain the coating amount T. T = E / S Further, in the film thickness calculator 14, the relationship between the viscosity and the temperature and the solid content concentration ρ obtained in advance is set for each paint to be used in the form of a table or a functional formula. The current paint type is supplied from the paint type setting device 17.

In the film thickness calculator 14, the type of paint supplied from the paint type setting unit 17 and the thermometer 12 are used.
Based on the temperature and the viscosity supplied from the viscometer 13, the solid content concentration ρ of the current coating material applied to the steel strip 7 is obtained, and the coating amount T supplied from the coating amount calculator 10 is calculated by the following formula. The coating film thickness T after drying is calculated by
D is calculated and supplied to the film thickness controller 19.

TD = ρ · T Here, the solid content concentration ρ is obtained by sampling and averaging at the same timing as the calculation logic of the consumption amount, or by sampling at the timing of obtaining the average value,
It can be determined by averaging two points at the timing of calculating the consumption amount, or by obtaining by sampling when calculating the consumption amount. However, the calculation time of the consumption amount (a predetermined time interval between the average value and the average value) is at most about 2 minutes, and it is assumed that the change in the solid content concentration during that time is minute, so the solid content concentration ρ is The above averaging is not always necessary.

The target film thickness TM is supplied from the target film thickness setting unit 18 to the film thickness controller 19, and the target film thickness TM is obtained.
Based on the deviation between the coating film thickness TD and the coating film thickness TD supplied from the film thickness calculator 14, it is possible to supply a rotation speed change command to the drive device 20 that drives the rotation speed of the pickup roll 1a. Next, the operation and effects of the device having the above configuration will be described.

The paint in the paint tank 4 is supplied to the paint tank 2 by the pump 6, and the paint which has passed over the weir 3 in the paint tank 2 returns to the paint tank 4 and the space between the paint tank 4 and the paint tank 2. The paint circulates. In this state, the paint in the paint tank 2 is continuously applied to the steel strip 7 sequentially fed by the coater roll 1. When the load cell 11 detects that the paint in the paint tank 4 is below the set lower limit value, the application amount calculator 10 supplies an open command to the shutoff valve 9 to refill the paint tank 4 with the paint. .

After that, after the circulation system of the paint between the paint tank 4 and the paint tank 2 is stabilized, the application amount calculator 10 calculates the application amount T by the sampling time Δt by the above averaging operation. The calculated coating amount T is supplied to the film thickness calculator 14. The film thickness calculator 14 calculates the coating film thickness TD on the steel strip 7 based on the coating amount T supplied from the coating amount calculator 10 and supplies the calculated coating film thickness TD to the film thickness controller 19. .

In the film thickness controller 19, if the coating film thickness TD is thinner than the target film thickness TM, based on the coating film thickness TD supplied from the coating amount calculator 10, the number of rotations of the pickup roll 1a of the coater roll 1 is increased. The coating thickness TD
If is larger than the target film thickness TM, the conventional film thickness control such as lowering the rotation speed of the pickup roll 1a of the coater roll 1 is performed.

As described above, in the calculation of the coating amount T by the coating amount calculator 10 of the present embodiment, the average value Di of the paint weight Wi obtained by shifting by the predetermined time Δt · m is obtained in the sampling time Δt unit. Therefore, it becomes possible to obtain the coating amount T at the sampling time Δt intervals while ensuring a predetermined measurement accuracy, and the plate thickness control quickness is improved. Further, since the film thickness calculator 14 obtains the coating film thickness TD to be applied to the steel strip 7 based on the solid content concentration ρ of the coating material, the variation due to the variation of the solid content concentration ρ is absorbed and the coating film thickness TD Measurement accuracy is improved.

Since the coating film thickness TD can be detected before and after the coating material is actually applied to the steel strip 7, the coating material coating on the steel strip 7 and the film thickness detection are performed. It is possible to shorten the dead time between the two, and the film thickness control accuracy is improved from this point as well. In the above embodiment,
Although the coating amount calculator 10 and the film thickness calculator 14 are described as separate devices for the sake of clarity, they may be configured by one device.

Further, when performing the averaging calculation in the coating amount calculator 10, the time required to measure the sampling number n is the time required to shift the two average values Di for calculating the paint reduction amount E. The case where the time interval Δt · m (m <n) shorter than the interval Δt · n is used has been described.
A time interval Δt · m (m = n) equal to the time interval of the sampling number n may be set. This is because, in the averaging calculation used in the present embodiment, the offset time interval Δt · m and the time interval for obtaining the coating amount are independent.

In the above embodiment, the application amount is not limited to the sampling time Δt, but the application amount may be obtained at a time interval twice the sampling time Δt. .

[0041]

EXAMPLE FIG. 3 shows changes in the coating film thickness TD when actually measured and controlled based on the above-mentioned embodiment. In FIG. 3, the solid line is based on the above embodiment. In addition, the dashed-dotted line shows the change in the coating film thickness by the conventional measurement and control for comparison.

As can be seen from FIG. 3, when the measurement and control are performed based on the above-described embodiment, the coating film thickness can be made to be a substantially constant value from the start of coating.

[0043]

As described above, according to the coating amount measuring method of the present invention, the average value of the predetermined number of samplings is calculated in the unit of sampling time, and the coating is performed based on the difference between the average values deviated by the predetermined time. Since the amount is calculated, even if the time interval for calculating the application amount is set to a short time interval such as a sampling time, the same measurement accuracy as in the conventional case is ensured. That is, the use of this application amount information has the effect of improving the quick response of the application amount control while ensuring a predetermined measurement accuracy.

Further, in the coating film thickness measuring method according to the second aspect, the variation in the film thickness due to the solid content concentration of the paint is absorbed, and the film thickness measuring accuracy is improved accordingly. That is,
The use of this film thickness measurement value has the effect of improving the accuracy in film thickness control.

[Brief description of the drawings]

FIG. 1 is a diagram showing a device configuration according to an embodiment of the present invention.

FIG. 2 is a diagram for explaining an arithmetic operation for averaging paint weights according to the embodiment of the present invention.

FIG. 3 is a diagram showing an embodiment of the present invention.

FIG. 4 is a diagram showing a configuration of a conventional device.

FIG. 5 is a diagram for explaining a conventional averaging calculation of paint weight.

[Explanation of symbols]

 1 coater roll 2 paint tank 4 paint tank (paint container) 5 supply pipe 7 steel strip 10 coating amount calculator 11 load meter 12 thermometer 13 viscometer 14 film thickness calculator 19 film thickness controller Δt sampling time n sampling number Δt ・m Shift time interval T Applied amount Wi Paint weight ρ Solid content concentration TD Applied film thickness

Claims (2)

[Claims] 1. When the paint in the paint tank is continuously applied to the continuously fed sheet-like continuous body, the paint weight in the paint tank or the paint container communicating with the paint tank is sampled at a predetermined time. A coating amount measuring method for measuring the coating amount on the sheet-like continuous body by sampling at each sampling time, and obtaining the average value of a predetermined sampling number unit for each sampling time, and averaging the values. A coating amount measuring method, characterized in that the coating amount is measured based on the difference between the value and the average value obtained when the sampling value is shifted by a predetermined time interval different from the sampling time. 2. The coating film thickness is measured from the coating amount obtained by the coating amount measuring method according to claim 1 and the solid content concentration of the coating substance obtained from the viscosity and temperature of the coating material. Film thickness measurement method.