JPH01282396A - Apparatus for controlling basis weight profile - Google Patents

Abstract

PURPOSE:To prevent the generation of saw-tooth profile on the basis weight of a paper by setting a limit on the difference of openings of adjacent slice bolts and outputting an operation signal corresponding to the weighted average of the openings of the surrounding slice bolts when the opening difference exceeds the limit. CONSTITUTION:Openings of a slice lip are controlled to control the basis weight profile by operating plural slice bolts based on the deviation from the determined value of the basis weight profile of a paper-making machine. In the above process, a limit is set on the difference of the openings between each slice bolt and adjacent slice bolts. When the operation of a slice bolt exceeds the limit value, the slice bolt is operated based on the value calculated by the weighted average of the openings of the slice bolts surrounding the objective slice bolt. No operation is applied to a slice bolt subjected to the weighted average when the operation direction based on each basis weight deviation is opposite to the operation direction based on the weighted average value.

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.

<Conventional technology> An overview of the papermaking process will be explained with reference to FIG.

Raw material pulp P passes through seed box 11 types 1] valve 2 and goes to white water silo 3
It is combined with the return 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 slicing lip 6, is squeezed out in the press part, heated and dried with steam in the dry part 10, and then transferred to the calender 11.
After that, it is wound up into a roll 12 to become a product. 7 is a plurality of (for example 6
0 slice bolts.

13 scans the product in the paper width direction to determine the basis weight of the paper (1 m2
This is a B/M meter that measures the weight (weight) and moisture content, and based on these measured values, the absolute dry basis weight profile of the paper is calculated by dividing the width direction of the paper into a plurality of points, for example, 360 points.

Absolute dry basis weight profile measurement value PV of each point determined by calculation
The difference between and the set value S is controlled and calculated by the profile control device 14, and the lip opening degree is adjusted by operating the slice bolt 7 corresponding to the measurement point using the operation output MV, so that the absolute dry basis weight profile of the product is adjusted to the set point. Feedback control is performed to match the dry basis weight profile.

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 top K fil of the paper 16 and the measurement points on the downstream side. For example, for 60 slice bolts 7.7...7, 360 measurement points P■ 1. P■2...PV36o is compatible, so
The measured values corresponding to the operating end of the slice bolt 71 are six measured values P■1. The average value PV1 of P22...PV is used, and the slice bolt 71 is operated by the operation output obtained by controlling and calculating the deviation between this measured value and the set value of the G0 fill. The operations for the other slice polls 1 to 1 are similar.

Fig. 6 shows an example of the result of profile control with such a configuration, and (A) shows a slice bolt 7.7.
...76o position, profile setting value S■, measured value P
It shows the relationship between the profile P F' connecting V, and (B) shows the operation output MV to each slice bolt, MV...M
The amount of operation of V e o is shown.

<Problems to be Solved by the Invention> In profile control with such a configuration, interference due to the movement of the paper material on the wire may be irregular, or there may be mismatches in the correspondence between the positions of the operating end and the measurement point. can be,
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, in the portion having the serrated profile, the opening degree of the slice lip also becomes serrated, and the difference in the opening degree between adjacent slice bolts becomes larger than that in other portions.

Slice bolts are arranged 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. Therefore, operations to absorb deviations cannot be performed 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> A structural feature of the present invention is that a plurality of slice bolts are operated as operation ends based on the deviation between the paper machine basis weight profile measurement value and the set value, and the lip opening degree is determined by these bolts. In a device that controls the basis weight profile by, an adjacent limit value is set for the opening difference between each slice bolt and the adjacent slice port, and if the operation amount to the slice bolt exceeds this limit value. In this method, there is a means for transmitting an operation output that is a load average of the slice bolt opening degrees around the slice bolt, and a means for transmitting an operation output that is a load average of the slice bolt opening degrees around the slice bolt, and a means for transmitting an operation output that is a weight average of the slice bolt opening degrees around the slice bolt, and a means for transmitting an operation output that is a weight average of the slice bolt opening degrees of the surrounding slice bolts. When it comes to things, the point is to control the amount of manipulation.

According to the present invention, when the operation amount to the slice bolt exceeds the adjacent limit value set for the opening difference between each slice bolt and the adjacent slice bolt, this The operation output is calculated by weight-averaging the slice bolt openings around the slice bolt.

Further, for each slice bolt whose weight has been averaged, the deviation in tsubom and the operation direction or the opposite direction after the load average are determined to be the amount of operation to that slice bolt.

<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 there is a pattern in which the opening is alternately high and low. 6 The present invention makes use of 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.

1 in the profile control device 'f114 based on FIG.
11M ability will be explained.

141 is a control calculation unit, which periodically calculates the basis weight measurement value P V
The surface difference between and set value Sv is calculated using P, l, and D control, and a calculation output U corresponding to each slice bolt is transmitted.

142 is an adjacent limit check section, and each calculation output U
Adjacent limit fM L s whose size is set
Check whether it exceeds t.

143 is a smoothing processing unit which, when there is a calculation output exceeding an adjacent limit value, calculates a weighted average of multiple adjacent calculation outputs including this calculation output, and checks that the calculation result is within the limit value. 6144 is a determination unit which confirms the calculation output of the control calculation unit that is the target of average calculation and replaces it with the weighted average calculation output, and determines the operation direction of this weighted average calculation output and the slice corresponding to each weighted average calculation output. The polarity of the basis weight surface difference glofil is checked, and if the polarity of the deviation is opposite to the operation direction, a process is executed to set the operation output to zero, and the operation output to each slice bolt is transmitted.

Fig. 2 is an explanatory diagram of the operation of the determination unit, and (B) shows the calculation output V of the two left and right slice bolts ■ to ■ centered on the slice ■ applied to the adjacent limit value, and the weight average calculation shown by the arrow. The operation direction is shown, and <A) shows the surface difference profile corresponding to each slice bolt. In this example, ■
Since the polarity of the deviation and the operation direction match in the case of and ■, the weighted average calculation output is supplied as MV, and the operation output MV of ■, ■, and ■ is operated in the opposite direction (direction to widen the 11ii difference) and the operation output MV is zero. do not execute.

Next, the operations of blocks 141 to 144 in FIG. 1 will be specifically explained with reference to the flowchart shown in pairs 3 and 1. To simplify the explanation, it is assumed that the slice bolts to be subjected to the smoothing calculation are three trees in total, two on both sides of the slice bolt that is applied to the limit.

Step (2) is the execution of a control calculation, which is a normal control calculation based on the I) ID calculation for the deviation between the measured ipv and the set value for each slice, and its output is U.

In step ■, for all calculation outputs U, the adjacent limit
It is determined whether or not the value is within the set value using the following determination algorithm.

: (u + u, )/2 u, l<Ls[+
−11+1 1 In other words, if the absolute value of the difference between the average value of the calculation output of both of the two rules and the calculation output of the self is the adjacent limit value and is less than 1°, proceed to step ① and operate the leakage value. Output as output MV.

In step (2), the calculation output 1] If the power is equal to the limit value, proceed to step (2) and 119.11-.

The weighted average operation for smoothing is calculated as follows for 11''f+1.

・ α IJ ±α U・ +−1−I I−201−111 11=α U 10α U, 10α1ui+11 −
1+-10] , + α u 6 + α U ・
ui+1 -1 1 0
1+1 1 ++2, where α is the weighted average coefficient, for example, α = 0.05. αo = 0.9, α
1=O-05 is selected.

Further, proceed to step (3) and set ui-1, ui.

The amount of change in the manipulated variable Δu−, Δu, for U.

l+1 +-11ΔII
1 + 1 or can be calculated as follows.

A u H-1-u H-I VV i-1Δ 1+
・=U, -W.

Δ 11 1,1” II i ・1 l
+1 where V'/ 2M/ -, VV l+1
is the current measured value of the slice port opening.

Next, in step (2), it is checked as follows whether or not the operating direction and basis weight deviation polarity match, and if they do not match, the change in the operating amount is set to zero in step (2).

For j=i+1 to i-1, let ΔI-3D be the j-th slide's Scholt's control deviation (a!11 constant value - set value). △U = ΔU.

J J J ΔB If D ≧0, then Δu=O J J (2) If Δu is 0, then ΔF) If D ≧0, ΔU −ΔUJ
J JΔB
If Dj < o, Δ11 j = Q.

In this example, for the sake of simplicity, the smoothing 1fill calculation target is made into 3 trees centered around the slice bolts hanging on the adjacent limit, or even if there are 5, 7, etc., the weighted average coefficient is 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 danger of a sawtooth profile is eliminated by weight average calculation processing based on a preliminary check using the adjacent limit values of the slicing bolt's operation force, and by calculating the deviation. This can be avoided by processing the operation amount to zero by checking the polarity and operation direction, so the permissible limit of feedback control can be expanded and the controllability of profile control can be improved.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of the present invention, and FIG.
Figure 3 is a flowchart showing the calculation procedure, Figure 4 is an illustration of the six papermaking processes, and Figure 5 is an explanation showing the correspondence between slice bolts and measurement points. 6 are explanatory diagrams 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] In a device that operates a plurality of slice bolts as operating ends based on the deviation between the paper machine's basis weight profile measurement value and a set value, and controls the basis weight profile by the lip opening degree of these bolts, each of the slice bolts and the adjacent slice bolts are Set an adjacent limit value for the opening difference between the slice bolts,
When the amount of operation to the slice bolt exceeds this limit value, there is a means for transmitting an operation output that is a load average of the opening degrees of the surrounding slice bolts centering on this slice bolt, and a means for transmitting an operation output that is a load average of the slice bolt opening degrees around the slice bolt, and A basis weight profile control device characterized in that when the basis weight deviation and the operation direction after load averaging are opposite, the operation amount is set to zero.