JPS6348994B2 - - Google Patents

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention provides a method for controlling the profile of absolute dry basis weight (weight per 1 m ² excluding water, expressed in g/cm ² ) in a paper machine control device. This invention relates to a device for controlling the opening degree of a slice lip to match a desired profile.

<Prior Art> The configuration of a papermaking control device and its problems will be explained with reference to FIGS. 6 to 11. Figure 6 shows the overall configuration. 1 is a seed box, 2 is a seed opening valve, 3 is a fan pump, 4 is a stock inlet, 5 is a slice lip, 6 is a wire part, 7 is a suction box, and 8 is a Spray part, 9 is dryer, 10
11 is a calendar, 11 is a reel, 12 is paper that becomes a product wound on the reel, and 13 is a silo for collecting white water. Reference numeral 14 denotes a basis weight sensor that scans the product 12 in the width direction to measure its basis weight and moisture content, and is realized by, for example, a combination of a β-ray basis weight meter and a near-infrared moisture meter. 15 is a control device that processes information from the sensor to calculate the profile of the absolute dry basis weight in the width direction of the product, and sends operation signals to the seed opening valve 2 and the slice lip according to the desired profile pattern and deviation. Send. Further, an operation signal is also sent to the dryer 9 in order to manage the moisture content.

FIG. 7 is a perspective view of the stock inlet 4, slice lip 5, and wire part 6, and FIG. 8 is a partially enlarged view of the slice lip 5. The slice lips 5 are lined up at a constant pitch (100 to 150 mm). A plurality of slice screw groups 16 attached with
₁ , ₁₆₂ , . . . _16o , the opening pattern of the gap 17 by the slice lip 5 can be finely adjusted. Reference numerals 18 and 19 are no deckles provided to prevent the paper stock discharged from the end of the slice lip from being discharged to the outside of the wire part.

Figure 9 is a diagram explaining the basic operation, and the horizontal axis is the paper width l.
The vertical axis represents the absolute dry basis weight BD. _S1 , _S2 ,...
S _o is the slice screw group 16 ₁ , 16 ₂ , ... 1
6 Indicates the position corresponding to each _o . E _P is the measurement profile of the absolute dry basis weight calculated based on the information from the sensor, _p is its average value, and S _p is the desired setting profile of the absolute dry basis weight. The opening degree of the seed opening valve 2 is controlled by an operation signal based on the deviation between _p and S _p , and in a state where _p matches S _p ,
The opening degree of the slice lip is controlled via each slice screw group based on the deviations ε ₁ , ε ₂ , . . . ε _o between the desired profile and the measured profile.
Adjustment of the slicing screw causes deformation of the slicing lip in that portion, changing the amount of paper stock discharged, and thus changing the absolute dry basis weight. Therefore, by adjusting the plurality of slice screw groups based on the deviation at each screw position, it is possible to control the plurality of slice screw groups to accurately match a desired profile.

However, adjusting the opening using the slice screw has the following problems. The first is that the operation of a slice lip causes deformation of the relevant portion, which affects the paper thickness of the portion corresponding to the adjacent slice lip centered around the slice lip at the operating position. Therefore, the operation signal for each screw cannot be determined independently, and it is necessary to consider the mutual interference between the operation amounts for adjacent slice screws. For example, as shown in FIG. 10, the deviation ε _k of the k-th slice screw position S _k
When the slice lip at position S _{k is} pressed by _the operation signal u _k based on changes as shown in the figure. Therefore, the operation signal for each screw must be calculated in consideration of such mutual interference, and the calculation algorithm becomes complicated.

The second problem is that there is a limit to the amount of manipulation of the slice lip by the slice screw between adjacent positions due to the rigid properties of the slice lip. For example, when the magnitudes of the operation signals at adjacent positions change alternately as shown in FIG. 11A, the amount that can be manipulated is small, and when they monotonically change as shown in FIG. 11B, the restrictions are looser than in A. Therefore, if the operating signal for each screw exceeds the limit due to the characteristics of the slice lip, an unreasonable force is applied to the slice lip, making it difficult to control with high precision.

<Problems to be Solved by the Invention> The purpose of the present invention is to solve the second problem mentioned above,
To provide a control device that provides a means for calculating an operation signal so that the amount of operation to each screw does not exceed a limit, and thereby also solves the first problem of mutual interference as a secondary problem. It is in.

<Means for Solving the Problems> The structural feature of the present invention is that the stock discharged from the stock inlet onto the wire part is adjusted by controlling the opening degree of the slice screw at a plurality of locations on the slice lip. In a paper machine control device that controls the bone dry basis weight to a desired profile, a bone dry basis weight measuring means and a position of the slicing screw are determined based on a deviation profile between the bone dry basis weight measurement profile and the desired profile. An operation signal calculating means for calculating an operation signal, and when the signal difference between adjacent position operation signals has the same polarity, compares the signal difference with a first set value, and when the signal difference has different polarity, compares the signal difference with a second set value. a smoothing means for performing a smoothing process on the deviation profile or the measurement profile when at least one output from the comparing means occurs; repeated execution means for repeating the execution of the operation signal calculation means and the comparison means until the output of the comparison means is no longer generated; and an output means for supplying the position operation signal to the position control signal.

<Function> A deviation profile between the absolute dry basis weight measurement profile calculated by the measurement using the basis weight sensor scanning batch and the desired setting profile is calculated and held. A position operation signal for each slice screw is calculated based on this deviation profile. Next, the polarities of adjacent signal differences of the position operation signals are compared, and if the polarities are the same, the difference between the operation signals is compared with the first setting value, and if the polarities are different, the second setting value (more than the first setting value) is compared. is selected to be small).
If even one signal difference exceeds the set value as a result of comparison, smoothing processing such as moving average processing is performed on the deviation profile or measurement profile, and the same procedure as above is performed on the corrected deviation profile obtained as a result. Position operation signal calculation and comparison are performed, and if even one signal still exceeds the set value, smoothing processing is further performed on the corrected deviation and the above processing is repeated. Then, the calculated output of the position operation signal at the stage when there is nothing exceeding the set value is transmitted as an operation signal to the slice screw.

<Example> FIG. 1 is a functional block diagram when each means of the apparatus of the present invention is processed by software, where F is a paper machine M having a slice lip 5 and a process 12.
The area R of the basis weight sensor 14 is the area of the control device 15. In region R, 151 is basis weight sensor 1
The bone dry basis weight measuring means 152 calculates the bone dry basis weight E _p based on the information of 4, and the bone dry basis weight measuring means 152 calculates the deviation profile ε _p between the profile of E _p and the desired setting profile S _p , and sends the scanning batch signal e. deviation holding means for holding the deviation profile of one scanning batch in synchronization with _b ;
Reference numeral 53 denotes an operation signal calculation means for calculating the position operation signal u of each slice screw based on the deviation profile ε _p , and 154 compares the difference between adjacent operation signals, and when the polarities are the same, the absolute value of the signal difference is calculated. A comparison means that compares the value with the first set value L _ss and, if the polarity is different, with the second set value L _ds (L _ds < L _ss ), and if even one difference exceeds the set value, the comparison is performed. output
If e _c1 occurs and a difference exceeding the set value does not occur, comparison output e _c2 is generated. Reference numeral 155 denotes a smoothing means, which performs smoothing processing on the deviation profile ε _p when receiving the comparison output e _c1 , outputs a modified deviation profile ε p ', and outputs the corrected deviation profile ε _p ′.
Give to 3. The operation signal calculation means 153 calculates the position operation signal for each slice screw again based on ε _p ′.
Compute u′. Comparison means 154 performs a comparison operation on this signal u' similar to that for u. If the comparison output e _c1 is generated as a result, smoothing processing is further performed on the modified deviation profile ε _p ', and the above processing is repeated. This iterative process is executed until the comparison output e _c2 is generated. Reference numeral 156 indicates an iterative control means for executing this iterative process. 157 is an output means which holds the outputs u, u'... of the operation signal calculation means, and when the comparison output e _c2 is received, the held output at that time is set as the operation signal output u _{0 and} is sent to the slicing screw of the paper machine. Send to.

Next, examples of specific signal processing modes of each means will be explained. In the operation signal processing means 153, assuming that the deviation corresponding to the k-th slice screw is ε _k , in order to cancel this ε _k , the position operation signal u _k of the slice screw is calculated by the proportional and integral operation of the following equation.

u _k = K _p (ε _k +1/T〓Σε ⁱ _k ) (1) Here, K _p and T〓 are the proportional and integral gains, and Σε ⁱ _k is the sum of deviations from the past to the present. Equivalent to.

Next, in the comparison means 154, as shown in FIG.
Differences Δu _{k and} Δu k+1 between adjacent operation signals for the operation signals u _k , u _{k+1 ,} and u _k+2 are calculated using the following equations.

Δu _k =u _k+1 −u _k , Δu _k+1 =u _k+2 −u _k+1 (2) (1) Condition-1 Δu _k *Δu _k+1 If >0, that is, both operation signals are changing in the same direction, Δu _k+1 ≦L _ss (3) (2) Condition −2 If Δu _k *Δu _k+1 < 0, that is, the difference between the two operation signals is opposite. If there is a change in the direction, Δu _k+1 ≦L _ds (4) is checked at all points for each operation signal. If even one point does not satisfy the above conditions, a comparison output e _c1 is output, and smoothing processing is performed on the deviation profile ε _p .

An example of smoothing in the smoothing processing means 155 will be explained with reference to FIG. A shows an example of the deviation profile ε _p , and the deviations at positions S _k-1 , S _k , and S _k+1 are expressed as ε _k-1 , ε _k , and ε _k+1 . (B) shows a modified deviation profile ε _p ′ obtained by performing moving average processing on the profile in (A). When focusing on ε _k , its moving average value ε _k ′ is given by ε _k ′=1/2j+1i _j 〓 ^i=-j ε _k+i (5). Here, j is selected to be 1 or 2, for example. When j=1, it is a moving average of three points, and ε _k ′=1/3 (ε _k+1 +ε _k +ε _k-1 ) (6).

The modified deviation profile ε _p ′ obtained by performing such a moving average for all deviations is the third
As is clear from the comparison between Figures A and B, the change becomes smoother and the difference between adjacent deviation signals becomes smaller.
Therefore, the difference between adjacent values of the position value operation signal of each point calculated based on this modified profile ε _p ′ becomes smaller, and the possibility that conditions 1 and 2 above are satisfied is lower than before the smoothing process. and increase.
With this kind of smoothing processing, the deviation profile becomes smoother as the number of processing increases,
Only the rough change tendency will remain, and the difference in position operation signals for adjacent slice screws will also be small, making it possible to keep the values within the limit values for operations in the same direction and in opposite directions.

By repeating the smoothing process, the above condition 1,
2 is satisfied, the comparison means 154 outputs a comparison output.
Since e _c2 is transmitted, the output means 157 supplies the operation signal profile at this time as the operation output u ₀ to the operation section of each slice screw of the paper machine.

Note that the smoothing process is equivalent to being executed on the measurement profile E _p in addition to being executed on the deviation profile as described above, and the same effect can be obtained.

FIG. 4 is a flowchart showing the processing procedure when the functions of the above-mentioned means are realized by software, and shows the deviation ε _k as a representative example. In this flowchart, if the number of smoothing processes exceeds a certain number (n), an error 1 output will be generated as an error, and if the magnitude of the operation signal u _k exceeds the maximum allowable value L _nax , recalculation will be executed. If this number of times exceeds a certain number of times (m), an additional function is provided to generate an error 2 output as an abnormality.

<Effects> The present invention avoids the sudden change pattern of the operation signal that causes unreasonable distortion in the slice lip, and improves the measurement profile by gradually reducing the deviation from the large undulations of the deviation profile. You can gradually approach the setting profile you want and smoothly match it. FIG. 5 is data obtained by simulation using a computer, and shows how the measured profile E _p gradually matches the set profile S _p as shown by a solid line → a dashed line → a dotted line.

As a result of executing control to avoid such sudden change patterns of operation signals, the difference in position operation signals to adjacent slice screws is limited to a certain range, so the first problem is the mutual interference mentioned above. It has also been confirmed that good control results can be obtained even without processing using a special compensation algorithm.

As explained above, according to the present invention, it is possible to simplify the control of the slice screw, which has traditionally been relatively difficult to control with high precision due to mutual interference and restrictions on the amount of operation, and obtain good control results. This makes it easier to manage the basis weight of higher quality.

[Brief explanation of the drawing]

Fig. 1 is a functional block diagram showing an embodiment of the present invention, Figs. 2 and 3 are explanatory diagrams of the operation of the comparison means and smoothing means, Fig. 4 is a flowchart showing the signal processing procedure, and Fig. 5 is a computer diagram. Diagram explaining changes in measurement profile due to simulation, Part 6
The figure is an overall configuration diagram of paper machine control, Figure 7 is a perspective view showing its partial configuration, Figure 8 is a partially enlarged view of the slice rip, Figure 9 is an explanatory diagram of basic control operation, and Figure 10 is a diagram showing the basic control operation.
FIG. 11 is an explanatory diagram regarding mutual interference, and FIG. 11 is an explanatory diagram regarding restriction of the amount of operation. 5...slice lip, 12...paper, 14...
Basis weight sensor, 15...control device, 151...measurement means, 152...deviation holding means, 153...operation signal calculation means, 154...comparison means, 155...
Smoothing means, 156... Iterative control means, 1
57...Output means.

Claims (1)

[Claims] 1. In a paper machine control device that controls the absolute dry basis weight to a desired profile by adjusting the stock discharged from the stock inlet onto the wire part by operating the opening degree of the slicing screw at multiple locations on the slicing lip, dry basis weight measurement means; operation signal calculation means for calculating a position operation signal of the slicing screw based on a deviation profile between the absolute dry basis weight measurement profile and a desired profile; Comparing means for comparing the signal difference with a first set value when the signal difference has the same polarity and comparing the signal difference with a second set value when the signal difference has different polarity, and at least one output from this comparing means is generated. In this case, a smoothing means performs a smoothing process on the deviation profile or the measurement profile, and the output of the comparison means generates an output of the operation signal calculation means and the comparison means based on the corrected deviation profile output of the smoothing means. Basis weight profile control comprising repetitive control means for repeating until the output is exhausted, and output means for supplying the output of the operation signal calculation means to the slice screw as a position operation signal when the output of the comparison means is not generated. Device.