JPH0583677B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to improving the controllability of profile control in a basis weight profile control process.

<Prior Art> An overview of the papermaking process will be explained with reference to FIG.
The raw material pulp P passes through a seed box 1 and a seed port valve 2, joins with the return material from the white water silo 3, and is supplied to a head box 5 by a 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 between the slice lips 6, is squeezed out in the press part 9, heated and dried with steam by the driver 10, and then passed through the calender 11 and wound onto the reel 12. It is taken and turned into a product. 7 is for controlling the gap of the slice lip (for example, 60
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. It is calculated by dividing the width direction into multiple points, for example 360 points.

The difference between the calculated absolute dry basis weight profile measured value PV and the set value SV at each point is determined by the profile control device 1.
The control calculation is performed in step 4, and the lip opening degree is adjusted by operating the slice bolt 7 corresponding to the measurement point using the operation output MV, and feedback control is performed so that the bone dry basis weight profile of the product matches the set bone dry basis weight profile. will be held.

15 is a man-machine interface that communicates with the control device 14 and has a profile display function.

FIG. 5 shows the correspondence between the slice bolts on the upstream side of the paper 16 and the measurement points on the upstream side. For example,
60 slice bolts 7 ₁ , 7 ₂ …7 ₆₀ to 360
Measurement points PV ₁ , PV ₂ ... Since PV ₃₆₀ corresponds,
The measurement value corresponding to the operating end of slice bolt 7 ₁ is:
The average value ₁ of the six measured values PV ₁ , PV _{2 .} . . PV ₆ is used, and the slice bolt 7 ₁ is operated by the operation output obtained by controlling and calculating the deviation between this measured value and the running value of the profile. The operation of other slice bolts is similar.

FIG. 6 shows an example of the results of profile control with such a configuration. (A) shows the positions of the slice bolts 7 ₁ , 7 ₂ . . . S ₆₀ and the profile setting values SV,
It shows the relationship of profile PF connecting measured value PV,
(B) is the operation output MV ₁ and MV ₂ to each slide bolt.
...Indicates the manipulated variable of MV ₆₀ .

<Problems to be Solved by the Invention> In profile control with such a configuration, interference due to movement of the paper material on the wire is irregular, and mismatches occur in the correspondence between the positions of the operating end and the measurement point. However, profile feedback control is not easy.

Therefore, the tolerance limits for process variations in control are small, and if these limits are exceeded, an undesirable sawtooth profile as shown in FIG. 6 will occur.

At this time, the slice lip opening degree of the portion having the serrated profile also becomes serrated, and the difference in the opening degree of adjacent slice bolts becomes larger than other portions.

Slice bolts are installed at regular intervals in the width direction of a single metal plate called a slice lip, and the difference in opening between adjacent slice bolts is limited to a range that does not cause permanent distortion of the slice lip. It is difficult to absorb the deviation sufficiently, and it is difficult to absorb the occurrence of a sawtooth profile using feedback control.

An object of the present invention is to provide a profile control device that can solve these problems.

<Means for Solving the Problems> The present invention achieves the above object by performing control calculations based on the basis weight deviation between the paper machine basis weight profile measurement value PV and the set value SV, and using a plurality of slices as the operating end. Basis weight profile control that has a control calculation unit 141 that transmits a calculation output u _i corresponding to the bolt, and outputs the difference between the calculation output of this control calculation unit and the current slice bolt opening degree as the operation amount of the slice bolt. The device has the following configuration.

That is, an adjacent limit check section 142 that checks whether or not the calculation output between each slice bolt and the adjacent slice bolt exceeds a predetermined adjacent limit value _LSL ;
If it is recognized that a calculation output to a slice bolt that exceeds the adjacent limit value has occurred in this adjacent limit check section, a smoothing process is performed to smooth the calculation output of the slice bolt related to this check and the slice bolt adjacent thereto. Section 143
And about this smoothed slice bolt,
Calculate the change in operation amount Δu _i , which is the difference between the calculation output after smoothing processing and the current slice bolt opening,
If the amount of change in the amount of operation is in a direction that increases the absolute value of the basis weight deviation corresponding to this sliced bolt, the operation direction determining unit 144 is provided, which sets the amount of change in the amount of operation to zero. It is said that

<Function> In the present invention, the adjacent limit check section has the following functions:
Mechanical limits in the operation of the slice lips are detected in advance to check for excessive irregularities in the amount of operation of each slice lip. The smoothing processing section is
Smooth the calculation output of each slice rip that has become uneven. If the change in the operation amount of a particular slice lip increases the control deviation due to the smoothing process, the operation direction determination unit sets this change in the operation amount to zero, eliminating the need for unevenness in the weighing profile. Prevent it from increasing.

<Example> An unfavorable profile that occurs during basis weight profile control begins to occur before the difference in opening between adjacent slice bolts reaches the above-mentioned limit value that causes permanent distortion, and moreover, there is a pattern in which the opening is alternately high and low. becomes. The present invention utilizes this property to perform a smoothing calculation of the operation output so as not to generate a sawtooth profile when the opening difference reaches a limit value.

The functions of the profile control device 14 will be explained based on FIG.

Reference numeral 141 denotes a control calculation unit, which calculates the deviation between the periodic basis weight measurement value PV and the set value SV by controlling P, I, and D, and transmits a calculation output u corresponding to each slice bolt.

Reference numeral 142 denotes an adjacent limit check section, which checks whether the magnitude of each calculation output u exceeds a set adjacent limit value _LSL .

143 is a smoothing processing unit which, when there is a calculation output exceeding an adjacent limit value, calculates a weighted average of a plurality of adjacent calculation outputs including this calculation output, and checks that the calculation result is within the limit value. , and replace the calculation output of the control calculation unit that is subject to average calculation with the weighted average calculation output.

Reference numeral 144 denotes a determination unit, which checks the operation direction of this weighted average calculation output and the polarity of the basis weight deviation profile of the slice corresponding to each weighted average calculation output, and if the polarity of the deviation is opposite to the operation direction, the operation is performed. Processing to set the output to zero is executed, and the operation output to each slice bolt is transmitted.

Fig. 2 is an explanatory diagram of the operation of the determination section, and B shows the calculation output v of the two slice bolts on the left and right with the slice applied to the adjacent limit value as the center, and the operation direction after the weight average calculation shown by the arrow. , (A) shows the deviation profile corresponding to each slice bolt. In this example, the polarity of the deviation and the operation direction match, so the weighted average calculation output is
MV is supplied as MV, and since ,, is in the opposite direction (direction to widen the deviation), the operation output MV is zero and no operation is performed.

Next, according to the flowchart shown in Figure 3, the first
The operations of blocks 141 to 144 in the figure will be specifically explained. To simplify the explanation, the number of slice bolts to be subjected to the smoothing calculation is assumed to be three in total, two on both sides of the slice bolt that is applied to the limit.

The step is the execution of control calculations, and the PID for the deviation between the measured value PV and the set value is calculated for each slice.
It is a normal control calculation by calculation, and its output is u
It is.

In this step, it is determined whether or not all calculation outputs u are within adjacent limit values using the following determination algorithm.

|(u _-1 +u _i+1 )/2−u|<L _SL In other words, the absolute value of the difference between the average value of the calculation outputs on both sides of the self and the calculation output of the self is the adjacent limit value L _SL
If it is below, proceed to step and output the calculated value as the manipulated output MV.

If the calculation output u is applied to the adjacent limit value at the step, proceed to the step and set u _-1 , u _i , u _i+1
The weighted average operation for smoothing is calculated as follows.

u _-1 ＝α _-1 u _-2 ＋α ₀ u _-1 ＋α ₁ u _i u _i ＝α _-1 ui _-1 ＋α ₀ u _i ＋α ₁ u _i+1 u _i+1 ＝α _-1 ui＋α ₀ u _{i +1} +α ₁ u ₊ 2Here, α _-1 , α ₀ , α ₁ are weighted average coefficients,
For example, α ₋₁ =0.05, α ₀ =0.9, and α ₁ =0.05 are selected.

Further, proceeding to step, the changes in the manipulated variables Δu _-1 , Δu _i , Δu _i+1 with respect to u _-1 , ui , u _i+1 are determined as follows.

Δu _-1 =u _-1 −w _-1 Δu _i =u _i −w _i Δu _i+1 =w _i+1 −w _i+1Here , u _-1 , w _i , w _i+1 are slice bolts This is the current measured value of the opening.

Next, in the step, it is checked as follows whether or not the operating direction and the basis weight deviation polarity match, and if they do not match, the change in the operating amount is set to zero in the step.

For j = +1 to -1, when ΔBD _j is the control deviation (measured value - set value) of the jth slice bolt, (1) When Δu _j ≧ 0, if ΔBD _j < 0, Δu _j = Δu _j ΔBD If _j ≧0, Δu _j =0 (2) When Δu _j <0, ΔBD _j ≧0, Δu _j = Δu _j If ΔBDj<0, Δuj=0.

In this example, for the sake of simplicity, the smoothing calculation targets are three, centered on the slice bolts connected to the adjacent limits, but even if there are five, seven, etc., the weighted average coefficient can be determined appropriately. Accordingly, the present invention can be applied.

The application example of the device of the present invention described above is aimed at controlling the paper profile in the papermaking process, but the same method can also be used to control the paper thickness profile, moisture content profile, and film thickness profile. It is possible to apply.

<Effects of the Invention> As explained above, according to the present invention, the risk of generating a sawtooth profile can be reduced by smoothing processing based on a preliminary check based on the adjacent limit value of the operation amount of the slice bolt, and by adjusting the operation amount of the slice bolt. When the amount of change is in the direction of increasing the control deviation, it is set to zero, thereby preventing unevenness in the operation amount of the slice bolt. Therefore, the permissible limit of feedback control can be widened, and the controllability of profile control can be improved.

In addition, as shown in the example, the smoothing process is performed in the third
As shown in the step in the figure, by adding weight α ₀ of the calculation output of the central slice bolt and decreasing weights α _-1 and α ₁ of the calculation output of the adjacent slice bolts as the distance from the center increases, The influence of bolt operation can be accurately reflected, allowing for more stable profile control.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of the present invention;
Figure 2 is an explanatory diagram of the operation regarding the deviation and operation direction, Figure 3 is a flowchart diagram showing the calculation procedure, and Figure 4 is a flowchart diagram showing the calculation procedure.
FIG. 5 is an explanatory diagram of the paper machine process, FIG. 5 is an explanatory diagram showing the correspondence between slice bolts and measurement points, and FIG. 6 is an explanatory diagram showing the relationship between the manipulated variable and the deviation value profile. 141... Control calculation section, 142... Adjacent limit check section, 143... Smoothing processing section, 144... Judgment section.

Claims (1)

[Claims] 1 Paper machine basis weight profile measured value PV and set value
Control calculation is performed based on the basis weight deviation of SV, and calculation output ui corresponding to multiple slice bolts as the operating end
In the basis weight profile control device, which has a control calculation section 141 that transmits a signal, and outputs the difference between the calculation output of this control calculation section and the current slice bolt opening as the operation amount of the slice bolt, This includes an adjacent limit check section 142 that checks whether or not the calculation output between adjacent slice bolts exceeds a predetermined adjacent limit value _LSL ; If it is recognized that a calculation output has occurred, a smoothing processing unit 14 smoothes the calculation output of the slice bolt related to this check and the slice bolt adjacent thereto.
3, for this smoothed slice bolt, calculate the change in the manipulated variable Δu _i , which is the difference between the calculation output after the smoothing process and the current slice bolt opening, and calculate the change in the manipulated variable as this A basis weight profile control device comprising: an operation direction determination unit 144 that sets a change in the operation amount to zero when the absolute value of the basis weight deviation corresponding to the sliced bolt is increased; .