JPH0547672B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Field of Industrial Application> The present invention relates to a method for determining the position of an absolute dry basis weight profile measurement point corresponding to the position of a slice bolt, which is an operating end, in a paper machine control system. .

<Prior Art> FIG. 5 is a schematic diagram of a papermaking process. Raw material pulp P passes through seed box 1, seed mouth valve 2, and then goes to white water silo 3.
It is combined with the return raw material from the pump 4 and supplied to the head box 5 by the pump 4. The raw material in the head box is discharged in the form of a sheet onto the wire part 8 from the gap in the slice lip 6, dehydrated in the press part 9, heated and dried with steam in the dry part 10, passed through the calender 11, and then reeled to the reel 1.
It is wound up into a product. 7 is a plurality of slice lips (for example, 40
This is a sliced bolt from the book.

13 is a B/M meter that scans the product in the paper width direction to measure the basis weight (weight of 1 m ² ) and moisture content of the paper, and based on this measurement value, the absolute dry basis weight profile of the paper can be determined. Multiple points in the width direction, e.g. 60 points or 360 points
Calculated by dividing into points.

The difference between the calculated absolute dry basis weight profile measurement value at each point and the set value is controlled and calculated, and the operating output is used to operate the slice bolt corresponding to the measurement point to adjust the lip opening. Feedback control is performed so that the basis weight profile matches the set bone dry basis weight profile.

<Problems to be solved by the invention> In the conventional absolute dry basis weight profile control system,
As shown in Fig. 6, the raw material discharged from the head box 5 through the lip immediately jumps out from the head box, flows straight on the wire, and shrinks uniformly during the drying stage. The bone dry basis weight profile is controlled by operating the slice bolts at the corresponding positions.

However, in reality, the raw material is not always discharged from the head box immediately, nor does it flow straight. Also, the shrinkage rate is greater near the paper edges than in the center. As described above, if there is a large misalignment between the actual measurement point and the position of the operating end, an undesirable profile sawtooth wave may be generated in absolute dry basis weight profile control.

An object of the present invention is to provide a method for determining the measurement point of a B/M meter corresponding to each slice bolt through a test before the start of product manufacturing.

<Means for Solving the Problems> The present invention achieves the above object, and when the k-th slice bolt arranged in the width direction of the paper is operated, the sensor scans reciprocatingly in the width direction of the paper and performs measurement. The following steps are performed in the bone dry basis weight profile measurement point determination method for determining which position of bone dry basis weight profile measurement is centered and where the influence appears.

That is, a reference value calculation step for calculating the reference value Di(o) at a plurality of absolute dry basis weight profile measurement points i in the paper width direction before operating the slice bolt, and a step for calculating the absolute dry basis weight profile after operating the k-th slice bolt. A step of determining whether the change has converged, and after the change in absolute dry basis weight profile has converged, the sensor scans n times and measures n.
The convergence value calculation process calculates the convergence value Di(n) by averaging the absolute dry basis weight profiles di(j), (0<j<n), and the reference value calculated in the reference value calculation process and convergence. Deviation from the convergence value obtained in the value calculation process Δi {=Di(n)−Di
(o)}, an area integration step for extracting data in the same direction as the scanning direction of the slice bolt from among the deviations obtained in this deviation calculation step, and calculating the area S; The method is characterized in that the procedure includes a positional correspondence determination step in which a measurement point i located at a position that equally divides the area of the profile is regarded as the k-th profile measurement point.

<Operation> According to the present invention, first, in the reference value calculation step, the reference value of the absolute dry basis weight profile before the slice bolt operation is calculated. Next, after the effects of the slice bolt operation converge, a convergence value calculation step calculates the average of several bone dry basis weight profile measurements to obtain a convergence value. Since the average is calculated, the influence of noise that appears in the paper flow direction and width direction is reduced. By further taking the deviation, the influence of the slice bolt operation can be extracted. In the area integration step, the amount affected by the slice bolt operation in the positive direction is evaluated, and in the position correspondence determination step, the position at which this area is equally divided is determined. Thereby, even if the shape of the deviation distribution is asymmetrical, valid positional correspondence points can be determined.

<Example> The procedure of the method of the present invention will be explained based on FIG.

In the step, the bone dry basis weight profile data before the slicing bolt operation is measured for multiple scans, and in the step, a time-series average calculation is performed for each measurement point on the measured data to obtain the reference value D _i of each measurement point. (o) is required.

Next, operate any k-th slice bolt,
Profile data is collected each time the sensor scans, and it is determined whether the profile change has converged.
With a normal paper machine, it takes about 10 minutes to converge.
Once converged, the profile data for n scans are measured in a step, and the average of the profile data is calculated to calculate the absolute dry basis weight profile convergence value Di(n). If you want to find the positional correspondence of all slice bolts, operate the slice bolts one by one starting from the first one, but to operate the next slice bolt,
This is after the deviation Δi has been determined.

After the change in the absolute dry basis weight profile converges, the deviation Δ _i between the reference value and the convergence value is calculated for each measurement point in the width direction using the data in step step.

In step, data in the same direction as the operation direction of the k-th slice bolt is extracted from the data of _Δi , and its area S is calculated.

In step, a measurement point i whose area is S/2 is calculated, and in step, the kth slice position is corrected to i.

If the shape of the deviation appears symmetrical, accurate positional correspondence points i can be obtained by curve approximation using a binomial distribution curve or the like, but in actual processes, it is often asymmetrical. In this case, approximation using a binomial distribution curve often does not work, but reliability increases if points are used to equally divide the area S. Here, all of the data in the same direction is used as the target for calculating the area S, but when a certain slice bolt is operated, a single peak curve appears in the deviation distribution, and since the contribution of the area S at the base is small, the position No large errors occur in determining corresponding points. Therefore, only the data in the same direction sandwiched between the data in the opposite direction may be subjected to the area S integration.

FIG. 2 is a flowchart showing the signal processing procedure of FIG. 1, and the processing from step to step is executed for all slice bolts.

Next, an example of the processing content of each step will be described, in which the processing is performed at 60 measurement points. FIG. 3 shows the absolute dry basis weight profile input data in the step, and d ₁ , _{d 2} , d ₃ . . . d _i .

In this step, the measured values for multiple scans are input and a time-series average calculation is performed for each measurement point. For example, suppose that the first scan and the nth scan are collected as follows.

(i) d ₁ (1), d ₂ (1)…d _i (1)…d ₆₀ (1) (ii) d ₁ (n), d ₂ (n)…d _i (n)…d ₆₀ ( n) Here, the average value for n scans at each measurement point is calculated by D _i (o)= _o 〓 ¹ d _i (k)/n, and D ₁ (o), D ₂ (o)...D _i ( o) …expressed as D ₆₀ (o). Note that the reference value may be determined based on measurement data d _i (1) obtained by one scan without taking a plurality of time-series averages.

Next, after operating the k-th slice bolt, wait until the profile data converges. Then, in a step, the converged flow data is collected for n scans. Assume that the collected measurement data is as follows.

(i) d ₁ ′(1), d ₂ ′(1),…d _i ′(1)…d ₆₀ ′(1) (ii) d ₁ ′(n), d ₂ ′(n),…d _i ′(n) …d ₆₀ ′(n) Calculate the convergence value of each measurement point by calculating the average value as D _i (n)= _o 〓 ¹ d _i ′(k)/n, D ₁ (n), Expressed as D ₂ (n), …D _i (n) …D ₆₀ (n).

In this step, the difference Δ _i at each measurement point is calculated based on the convergence value data and the reference value data as Δ _i =D _i (n)−D _i (o). .

Next, data in the same direction as the operating direction of the operating slice is extracted from the data of _Δi , and its area S is calculated in a step as shown in FIG.

Next, in a step, a measurement point i that divides the area S into two is calculated. Since this point i is the point most affected by the slice operation, the measurement point corresponding to the operated slice is regarded as the k-th profile measurement point, and in step the measurement point of the k-th slice bolt is This point is then corrected to be the center point of the control deviation calculation.

In addition, when performing control to set the measurement point to l point, the calculation of i=k·l/60 is performed to determine the correspondence relationship.

Through such a procedure, production is started after determination of corresponding measurement points for all sliced bolts is completed.

<Effects of the Invention> As explained above, according to the present invention, the profile data after convergence is averaged over several scans to obtain the convergence value, so the influence of random noise occurring in the paper flow direction and width direction can be reduced. . Also, in the deviation calculation process, the deviation between the reference value and the convergence value is calculated, so
Information that faithfully reflects only the influence of the operated slicing bolt is obtained by removing the influence peculiar to the paper machine. Furthermore, the area of this deviation is determined from only the direction data that is the same as the operating direction of the slice bolt, and the points that equally divide this area are used as corresponding points, so even if the shape of the deviation is asymmetrical, there is a valid positional correspondence relationship. This has the effect that the following can be obtained.

In the basis weight control device, a slicing operation is performed to obtain a uniform profile, but by accurately determining the positional relationship between the operating end and the measuring end, it is possible to prevent sawtoothness of the profile due to positional misalignment. This has the effect of suppressing wave waves and significantly improving the controllability of absolute dry basis weight profile control.

[Brief explanation of the drawing]

Figures 1 and 2 are block diagrams and flowcharts showing the signal processing procedure of the method of the present invention, Figure 3 is an explanatory diagram showing an example of measurement data of bone dry basis weight profile, and Figure 4 is an area diagram. FIG. 5 is a schematic diagram of the papermaking process, and FIG. 6 is an explanatory diagram showing the relationship between the operating end and the measurement point. 1... Seed box, 2... Seed mouth valve, 3... White water silo, 4... Pump, 5... Head box, 6...
...Slice lip, 7...Slice bolt, 8...
...Wire part, 9...Press part, 10...
...Dry part, 11...Calendar, 12...
Reel, 13...B/M total.

Claims (1)

[Claims] 1. When the k-th slice bolt arranged in the width direction of the paper is operated, the sensor scans reciprocatingly in the width direction of the paper and measures the absolute dry basis weight profile at which position as the center. In the bone dry basis weight profile measurement point determination method for determining whether an influence appears, a reference value calculation step of calculating a reference value Di(o) of a plurality of bone dry basis weight profile measurement points i in the paper width direction before slicing bolt operation; After operating the k-th slice bolt, a step of determining whether the bone dry basis weight profile change has converged; and after the bone dry basis weight profile change has converged, the sensor scans n times and measures the Average the basis weight profile di(j), (0<j<n) to find the convergence value.
A convergence value calculation step to obtain Di(n), and a deviation Δi {=Di(n)−Di(o)} between the reference value obtained in the reference value calculation step and the convergence value obtained in the convergence value calculation step. an area integration step for extracting data in the same direction as the slice bolt scanning direction from the deviation obtained in this deviation calculation step and calculating the area S; and a position to equally divide the area obtained in this area integration step. A method for determining an absolute dry basis weight profile measurement point, comprising: a step of determining positional correspondence in which measurement point i located at is regarded as the k-th profile measurement point;