JPS63182491A - Control of thickness profile - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention relates to a thickness profile control method for controlling the thickness profile in the width direction of a film, etc. The present invention relates to a thickness profile control method suitable for use in controlling a volume profile.

<Prior art> Fig. 6 shows a schematic diagram of a paper making device. In FIG. 6, the raw material Valve is placed in a seed box 1, its flow rate is adjusted by a seed port valve 2, and the raw material is supplied to an inlet box 4 by a fan pump 3. The valve in the inlet box 4 is discharged in the form of a sheet from the gap in the slice lip 5 to the wire bar 6.

The gap between the slice lips 5 is controlled by a plurality of slice bolts 7, and the profile of the gap can be varied. The pulp discharged in the form of a sheet is dehydrated in a breather 8, heated and dried with steam in a dryer 9, and then wound around a reel 11 in a calender 10 to become a product. Reference numeral 12 denotes a white water silo, in which the valve separated from the seat is collected by a wire bar 6 and returned to the inlet box 4. The thickness of the paper is controlled by the basis weight, which is the weight per 1 (112), and the widthwise profile of this basis weight and moisture is detected by the B/M detector 13.

The thickness profile is controlled by controlling the slice bolt 7 using the basis weight output of the B/M detector 13 and changing the gap opening degree of the slice lip 5. Not only the position but also the basis weight of the surrounding slice bolt position changes. Therefore, when operating a certain slice bolt, the surrounding slice bolts are also operated using a υ control signal obtained by multiplying the control signal for operating this slice bolt by a distribution coefficient. A control method for performing such control will be explained next. FIG. 7 shows the configuration of a W control device that executes this control method. 7th
In the figure, the gap opening degree of the slice lip 5 and the B/M
The analog signal of tsubom in the width direction measured by the detector 13 is A
The signals are converted into digital signals by the /D converter 14 and input to the display unit 16 via the I10 controller 15, where their profiles are displayed. Further, the measured value of the basis weight is input to the distribution coefficient calculating section 20. The distribution coefficient calculation unit 20 calculates a distribution coefficient from the input basis weight measurement value. This calculated distribution coefficient can be input to the distribution control calculation section 18.

In addition, the measured value of basis weight is input to the P-I control calculation section 17,
Luli control signal is calculated. This control signal is input to the distribution control calculation section 18, where it is distributed according to the distribution coefficient input from the distribution coefficient calculation section 20, the control signal is dedicated, and the D/A conversion section 19 converts it into an analog signal. The slice bolt 7 is controlled by the signal.

Next, the operation of this conventional example will be explained. Let the number of the slice bolt you want to operate be i, and the effect of operating this slice bolt will be on the two slice bolts on the left and right sides (numbers i-2 to
It is assumed that the basis weight extends to the position i+2). The P-■ control calculation unit 17 calculates the control signal LJi according to equation (1).
・・・・・・・・・(1) KP: Proportional gain Kx: Integral gain ΔBt: Deviation between the measured value and the target value of tsubom Also, the distribution coefficient calculation unit 20 calculates the distribution coefficient α section +2 to αt−2 as follows. Calculate based on an expression.

I CRt 421-1 t)mt +21/PIat
++ l=Ibmt ++ l/Plat l
-lbmi I/Plcr(-11-1brrB
-1l/Pl (Z(-21-1bm(-21/P・
・・・・・・・・・(2) However, bmL+2-bmt-,: Measured value of tsubo at the position of i+2 to i-2nd slice bolt P-Ibmt +2 l+1brrB ++ l+
1brT'J l+lbmt-1l+lbm(-21. The signs of the distribution coefficients αL +2 to αi-2 are basically the same as the signs of the measured values of basis weight. The distribution control calculation unit 18 calculates the control signal U( and distribution coefficient αt +2~α
The control signal UL for the i+2 to i-2 slice bolts from t-2 is calculated based on the following equation.

Ui =Olt +2 ut'+2+αt ++ UL
++αLuL×αi −1ut −1+ αt −2uL −2 (3) Each slice bolt is controlled by these control signals.

In addition, when a plurality of basis weight measurement points correspond to one slice bolt, the average of the measured values of those measurement points may be set as the basis weight measurement value bml-2 to bml+2. A feature of this control method is that the distribution coefficient can be automatically determined. The applicant proposed a control device for carrying out this control method in Japanese Patent Application No. 61-264743. <Problems to be solved by the invention> However, such a thickness profile control method has the following problems. There are some problems. There are a plurality of slice bolt and basis weight measurement points, and the correspondence between them is not necessarily clear, and the correspondence must be determined from the change in the constant basis weight value by manually operating the slice bolt. In the above explanation, it is assumed that this correspondence relationship is known. Furthermore, unless this correspondence is actually known, the control state cannot be entered.

However, it is nearly impossible to find correspondence across the entire width of the paper. Make appropriate assumptions for sections where no correspondence is required! 1w may be considered, but if the assumption is not appropriate, controllability may deteriorate due to correspondence errors, and the profile may diverge into a sawtooth shape. Therefore, determining the positional correspondence requires an expert to spend a lot of time off-line. Since this positional correspondence changes depending on changes in the brand and operating conditions, a new positional correspondence must be determined each time, resulting in a lot of time and waste.

<Objective of the Invention> An object of the present invention is to provide a thickness profile control device that can automatically determine the correspondence between measurement points of measurement values representing thickness such as basis weight and the position of a slice bolt.

<Means for Solving the Problems> In order to solve the above-mentioned problems, the present invention provides a control method used in a manufacturing apparatus that manufactures sheets by discharging raw materials from a slice lip that can change the profile of the gap using a slice bolt. Then, a quantity related to the thickness of the sheet is measured, a control signal is calculated from the deviation between the measured value and the target value by proportional integral calculation, etc., and this IIJ control signal is set in a positional relationship with the slice bolt. In the thickness profile control method, the slicing bolt is distributed at a ratio related to a measured value of a quantity related to a certain thickness, and the slicing bolt is distributed and controlled by the distributed control signal, the slicing lip being divided into a plurality of sections. , r to the opening signal and thickness of the sliced bolt in each divided section.
The positional correspondence between the position of this sliced bolt and the measurement point of the quantity related to the thickness is determined from the IA series of measurements of the thread, and the positional correspondence has not yet been determined by interpolation or extrapolation from this positional correspondence. The method of determining thickness is characterized in that the positional correspondence between the position of the slice bolt and the mother measurement point related to the thickness is determined, and partial distribution control is performed only in the section for which the positional correspondence has been determined among the divided sections. This is a profile control method.

<Embodiment> FIG. 1 shows the configuration of an embodiment of a control device for carrying out the thickness profile control method of the present invention. Note that this embodiment will be explained using a paper making process as an example. Also, the same elements as in FIG. 7 are given the same reference numerals, and their explanations will be omitted. In FIG. 1, reference numeral 30 denotes a partial calculation section, which is provided corresponding to the section of the divided slice lip. Partial operation section 3
0 includes a partial P1i/It11 calculation section 31, a partial position correspondence determination section 32, a partial distribution control calculation section 33, and a partial distribution coefficient calculation section 34. These parts P-I control calculation section 31
, partial distribution control calculation section 33, and partial distribution coefficient calculation section 34 operate in the same manner as the P-I control calculation section 17, distribution control calculation section 18, and distribution coefficient calculation section 20 of the conventional example shown in FIG. 7, respectively.

However, the calculation is performed only for the corresponding divided slice lip section. The partial position correspondence determination unit 32 receives the gap opening degree signal of the slice lip 5 and the output (basis weight) of the B/M detector 13, and detects the position of the slice bolt 7 in the divided section and the B/M detector. The correspondence between the 13 measurement points is determined. Reference numeral 35 denotes a manual control section for sections whose positional correspondence has not been determined, and the operator controls the gap opening degree of the slice lip 7 displayed on the display section 16 and the B/M detector 13.
The slice bolts are manually controlled in sections of the slice lip 5 in which the positional correspondence between the slice bolt positions and the measurement points of the B/M detector 13 has not been determined.

Next, an embodiment of the control method will be described. FIG. 2(A) is a diagram showing the positional correspondence relationship between the slice bolt 7 and the measurement point of the 8/M detector 13 immediately after the start of control.

In this figure, (b) shows the measurement point of the B/M detector 13, and (C) shows the position of the slice rotor.

i+4 to i-5 are slice bolt numbers.

This slice bolt is divided into several sections R1 to R3 as shown in (d). In this example, each section is divided to include five slice bolts. (a) shows the B/M detector 13 when operating a certain slice bolt.
This is an interference pattern showing the output pattern of . From this pattern position to the slice bolt position and B/M detector 1
It is possible to determine the positional correspondence of the three measurement points. In this figure, i+3. Only the positional correspondences between the positions of the i and i-5th slice bolts and the measurement points of the B/M detector 13 are determined, and they are deviated from the physical correspondence by −2° −1 and +2, respectively. The positional correspondence is determined by the partial positional correspondence determination unit 3.
2 is the slice lip of each section Question 1lif7f1 degree and B
/M The output of the detector 13 is searched and automatically performed. In this state, the operator manually operates the slice bolts in all sections.

FIG. 2 (8) is a diagram showing the state after a predetermined period of time has elapsed. The meaning of each symbol is the same as in (A). In this figure, all slice bolts i-2 to i in section R1
-6 positional correspondence has been determined. In this state, the partial calculation unit 30 executes distribution control only in the section R1.

That is, the partial P-■ control calculation section 31 calculates the control signal LJi according to the above-mentioned equation (1), and outputs the calculation result to the partial distribution coefficient calculation section 33. Further, the partial distribution coefficient calculating section 34 calculates the distribution coefficients αL and 2 to αt-2 from the measured values of the B/M detector 13 according to the above-mentioned equation (2), and outputs them to the partial distribution control calculating section 33. The partial distribution control calculation unit 33 calculates the control signal Ut from these values according to the above-mentioned equation (3). This calculated control signal is converted into an analog signal by the D/A converter 19 and output to the corresponding slice bolt.

Note that slice bolts in other sections whose positional correspondence has not been determined are manually operated by the operator.

Since it would be time-consuming and wasteful to have all positional correspondences determined, some positional correspondences are determined by interpolation or extrapolation from already determined correspondences. An example of this interpolation and extrapolation method will be explained based on FIG. FIG. 3(A) is a diagram showing the interpolation method.

The meanings of the symbols are the same as in FIG. In this figure, it is assumed that the positional correspondence between the i+2th and i-1th slice bolts is known, and the positional correspondence between the i+11th and iltth slice bolts is determined from these values. The measurement point of the B/M detector 13 between the 1+2nd and i-1th slice bolts is 811 m, and two slice bolts must be located between them. Since each slice bolt is usually spaced the same distance apart, points that are 8/3-2.67:3 apart from each other are made to correspond. i.e. ill, i
+1? B/M detector 1 corresponding to the first slice bolt
The measurement points No. 3 are points 3 and 6 away from the measurement point corresponding to the i-1th slice bolt.

FIG. 3(B) shows the extrapolation method. In this figure, 1
The positional correspondence of the i-1th slice bolt is extrapolated from the positional correspondence of the th slice bolt. As is clear from the figure, the first slide bolt is shifted to the right by +1 from its physical corresponding position. Therefore, the positional correspondence of the i-1th slice bolt is also determined to be shifted to the right by +1.

These interpolation and extrapolation processes are automatically executed by the partial position correspondence determination unit 32.

In such partial distribution Ill III, it is an absolute condition that the positional correspondence between the slice bolt position in this partial section and the measurement point of the B/M detector is accurate, and if there is an error in the correspondence, Controllability deteriorates.

In particular, there is a high possibility that errors will occur in position correspondence relationships determined by interpolation or extrapolation. Next, a method for preventing deterioration of controllability due to such errors in positional correspondence will be described. For this purpose, it is assumed that section Ri was partially controlled in the previous partial control, and section RJ was added this time. At this time, the maximum value of the amplitude of the deviation of the basis weight profile detected by the B/M detector 13 in the previous partial control (section R1) is At, and the amplitude of the deviation in the current partial control wJ (section R, +RJ) is If the maximum value of is Ai+J, then when Aj+J At>O, it is determined that controllability has deteriorated by adding section Rj to partial control, and section RJ is removed from partial control, and the positional relationship of section RJ is re-evaluated. Re-determine, At +j A
When t≦0, it is determined that the controllability has not deteriorated and partial control is continued. FIG. 4 shows the i difference in basis weight profiles.

FIG. 5 shows a 70-day diagram of the operation of this embodiment. Control begins with manual control by an operator, and the entire slice lip is divided into N parts. Processing of these divided sections is performed sequentially. First, the positional relationship between the slice bolt and the basis weight measurement point of the B/M detector 13 is determined from the change in the gap opening degree of the slice lip and the basis weight profile of the section to be processed.1. Check the number. Next, an interference pattern is obtained from the determined positional correspondence, and an interference width is estimated. If the determined number of slice bolts is smaller than a certain value, that section remains under manual control, and processing moves to the next section. If the number of bolts for which the positional correspondence has been determined is equal to or greater than a certain value, the positional correspondence of the remaining slide bolts for which the positional correspondence has not been determined is determined by interpolation or extrapolation. This constant value is determined based on the number of slice bolts in one section and experience, within a range that reduces the rate at which controllability deteriorates. Once the positional relationship of the required number of slice bolts is determined, the distribution coefficient is calculated and automatic control is started for that section only. This transition is performed by an operator's operation. When shifting to automatic control, deterioration of controllability is checked based on the change in the maximum amplitude of the profile of the deviation from the target value of basis weight, and if no deterioration has occurred, processing moves to the next section.

If it has deteriorated, check to see if there has been a change in the brand or operating conditions, and if there has been a change, reset all calculations and return to the start. If not, correct the positional correspondence obtained by interpolation and extrapolation. Then process that section again. In this way, all sections are sequentially processed and automatic control is started.

Although the paper-making process has been described in this embodiment, the present invention can also be applied to controlling the thickness profile of other films, etc. In that case, the tsubom is a quantity related to the thickness of the film, and the slice lip and slice bolt represent devices that function equivalently.

In addition, the positional correspondence of the slice bolts is determined by (1) performing an integrated calculation process on the correlation between the slice bolt gap opening degree signal and the measured quantity related to the thickness;

■Use the root mean square of the measured quantity data related to thickness excluding the initial value.

This can be done using the following methods.

・〈Effects of the Invention〉 As specifically explained above based on the embodiments, in this invention, the slice lip is divided into a plurality of sections, and in each of the divided sections, the amount related to the slice bolt and the thickness is The positional correspondence of the measurement points is determined by interpolation and extrapolation from the slice lip gap opening signal and the thickness-related measured value, and from the known positional correspondence. Once the number has been determined, distribution control is applied only to that section. Therefore, partial distribution control can be started from the section for which the positional correspondence has been determined, reducing the burden on the operator and improving controllability.

Furthermore, since the position correspondence relationships are determined by interpolation and extrapolation, it is possible to shift to distribution control even if all position correspondence relationships are not determined, and the start-up can be improved.

Furthermore, since the positional correspondence is estimated by interpolation and extrapolation only within the divided sections, it is possible to minimize the deterioration of controllability due to errors in the correspondence and to speed up the start-up.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of the device used in the thickness control method according to the present invention, and FIG. 2 is a diagram showing the positional correspondence between the positions of slice bolts and measurement points of quantities related to thickness. , Fig. 3 is a diagram showing the method of interpolation and extrapolation, Fig. 4 is a characteristic curve diagram for explaining the determination of controllability deterioration, Fig. 5 is a flowchart showing the control method, and Fig. 6 is a paper making method. FIG. 7 is a block diagram of a conventional thickness profile control device. 5...Slice lip, 7...Slice bolt, 1
3... B/M detector, 30... Partial calculation section, 31.
. . . Partial P-I control calculation section, 32 . . . Partial position correspondence determination section, 33 . . . Partial distribution control calculation section, 34 . . . Partial distribution coefficient calculation section. Figure 7 (A) (B) (d) R3R2R1 Figure 3 (A) (B) Figure 4

Claims (1)

[Claims] A control method used in an apparatus for producing a sheet by discharging a raw material from a slicing lip whose gap profile can be changed by a slicing bolt, and in which a quantity related to the thickness of the sheet is measured. A control signal is calculated from the deviation between the measured value and the target value, and this control signal is distributed in a ratio related to the measured value of the measurement point of the quantity related to the thickness that corresponds to the position of the sliced bolt, and this distribution is performed. In the thickness profile control method, the slice lip is divided into a plurality of sections, and the opening data and the thickness of the slice bolt in the divided sections are The positional correspondence between the position of this sliced bolt and the measurement point of the quantity related to thickness is determined from the measured value of the related quantity, and from this determined positional correspondence, interpolation or extrapolation is used to calculate the divided The position correspondence relationship between the positions of other slice bolts in the section and the measurement points of quantities related to thickness is estimated, and the positions of slice bolts in this divided section and the measurement points of quantities related to thickness are estimated. A thickness profile control method characterized in that partial distribution control is performed only in sections for which a positional correspondence relationship has been determined.