Basis Weight Profile Research Articles

Multidimensional Interpolation Decoupling Strategy for CD Basis Weight of Papermaking Process

With a focus on the multivariable coupling characteristics in a cross-directional (CD) basis weight control system, we study the coupling characteristics of a CD control system and decoupling control, and we propose a novel multivariable interpolation decoupling control strategy and a real-time decomposition algorithm in this paper. Based on a model of the CD basis weight profile, a system non-square interaction matrix of high-dimensional data is analyzed by experimental studies and numerical simulation. Along the diagonal of the interaction matrix, the matrix block method is adopted to reduce the system dimension and convert it into a square system. A multivariable control system with high dimensionality is divided into several subsystems. For the high-dimensional Toeplitz symmetric subsystem with small-scale coupling characteristics, an interpolation decoupling algorithm is proposed. Then, a decoupling compensator with the structure of a symmetric Toeplitz matrix was obtained. Compared with the conventional diagonal decoupling matrix, the branch number of the new decoupling network is reduced from 2408 to 186, which realizes the fast decoupling of multivariable systems. The results were even better when we used a double size interaction matrix obtained by interpolation between actual values. By designing the diagonalized controller for the new decoupled system, a decouped CD control system for corrugated paper with a basis weight of 133 g/m2 was implemented in an actual project in a paper mill.

Cross‐directional Estimation and Predictive Control of Paper Machines Using DWT

AbstractThis paper proposes a novel approach for cross‐directional (CD) estimation, modeling and control on paper machines based on discrete wavelet transforms (DWT). The CD basis weight variations are approximated at various resolutions using wavelet multiresolution analysis (WMRA). The controllable component of CD variations can be extracted from the original samples by choosing a suitable threshold resolution. An acceptable response model describing the relationship between the settings of the slice‐screws to the basis weight profile is obtained. The controller synthesis, model prediction, optimization and parameter estimation are all performed in the DWT domain. The size of optimization and control problems associated with such large dimensions can be significantly reduced.

Feedback Control of the Dry Line on Wire of Paper Machine

Two methods for instrumental measurement of the dry line have been developed. They are based on innovative arrangements of illumination and related observation under which the pulp on wire is seen by video camera as a composition of dark and light fields. The complete dry line is extracted from the image and used industrially for feedback control of the dry line in machine direction (MD). Recorded correlations between changes of dry line and dry basis weight profile justify conclusions on their control in cross direction (CD) and on incorporation of dry line measurement into conventional MD and CD controls which are handicapped by a long process delay.

ヘッドボックスからプレスまで ヘッドボックスに関する最近の設計思想 モジュールジェットヘッドボックスとその最新技術

We got the remarkable improvement of the CD basis weight profile by introducing the stock consistency control. New adjusting device and sensor for CD fiber orientation profile control are developed and we will be able to control the fiber orientation profile as well as basis weight profile. However the headbox has influenced the various fields of paper making not only CD profile control but also formation, variation on the MD, easy operation and simple maintenance. The Module Jet headbox of IHI-Voith Sulzes Paper Technology which was released in 1994 has achieved high performance on those any fields, and about eighty (80) Module Jet headboxes are operating all over the world.This report shows our design concept and newest technology of headbox.

Expert Fuzzy Control of Basis Weight Profile in Paper Machines.

Expert Fuzzy Control of Basis Weight Profile in Paper Machines.

高速新聞抄紙機のウエットパート

MHI High Speed Newsprint Machines have been developed to produce paper of the highest quality using 'state of the art' technology verified by the data from our field operations. Focussing on the 'Wet End' of the machine, the main features and resulting performance are hereby outlined.The “Concept IV-MH” Headbox has been developed and designed to deliver a uniform and stable jet at high speed. It has achieved an excellent dry basis weight profile (2 sigma= 0.13 g/m2) and uniform fiber orientation profile (less than +-2 degrees) by combining the latest technology such as “Dual Temperature Controlled Water Re-circulation”, “Edge Flow Control” and “Consistency Profile Control (CP)” system.The “MH Former +CB” can produce paper of superior quality in comparison with the “Roll Blade” type former due to the following unique features it offers.(1) Small diameter of the Forming & Breast roll makes for easy jet impingement adjustment.(2) The large radius Forming Board and alternative drainage equipment's arrangement in both wires perfects symmetrical sheet structure.(3) Location adjustable “Serrated Shoe” together with “Counter Blades” enables optimum dewatering conditions over a wide range of operational speeds.Results to date have realized and confirmed our goal of the “MH Former +CB” which produces paper of even sided sheet with excellent formation. In addition to the Head Box and Former developments, our latest Newsprint Machines are further equipped with new technology such as.-Enclosed type Shoe Press (ENP-C) -Anti-blowing boxes in the Dryer section-Center Wind Assisted Reel (TNT-C) All the above features are operating with great success in our latest High Speed Newsprint Machines, both in “Oji Paper Tomakomai mill N-6 M/C” and Iwaki-Daio Paper # 2 machine.

計装 ヘッドボックス希釈方式によるＢＤプロファイル制御 日本製紙（株）石巻工場Ｎ２Ｍ／Ｃ（ＩＨＩ・フォイト製）

計装 ヘッドボックス希釈方式によるＢＤプロファイル制御 日本製紙（株）石巻工場Ｎ２Ｍ／Ｃ（ＩＨＩ・フォイト製）

Adaptation of cross-direction basis-weight control in paper machines using fuzzy decision logic

An important quality characteristic in the production of paper webs is the range of fluctuations in the basis weight. This should be kept as small as possible. The basis-weight profile is a measure of these fluctuations. Deviations in the profile that arise during the papermaking process can be rectified by installing slice screws across the web and by suitable control functions. However, due to web shrinkage and displacement in the cross direction, the location on which a slice screw is acting in the profile is not known. This relationship, or mapping, is an essential precondition for cross-direction control. If it cannot be implemented accurately enough, the profile develops unevenness and, in the worst case, becomes unstable. This paper describes a method that identifies this relationship by means of statistical process and a fuzzy decision logic, and that appropriately adapts cross-direction control.

新型ヘッドボックス・シムフロ‐Ｄ

The fiber orientation misalignment profile has been recently more important property for some fine paper grades as well as formation and CD basis weight profile.“Sym-Flo D” is the latest headbox which has been developed to satisfy the above-mentioned market demand. This headbox has many advantages by applying the dilution concept to conventional Sym-Flo headbox.

塗工量プロファイル制御

We have developed cross direction coat weight control for coater machines and just applied it to an actual process recently. The operation under control started February 1995 and has gained much effect for operation and good customers satisfactions.The control algorithm is based on our basis weight profile control algorithm that uses expert fuzzy logic and has been applied to many paper machines. And we have added some special algorithm developed for coater machines to the algorithm.

ＩＨＩ‐ＶＯＩＴＨ新型ヘッドボックスの紹介 モジュールジェット・ヘッドボックス

IHI-VOITH has developed a new headbox with Module Jet. In this new headbox, the CD basis weight profile is controlled by locally changing the stock consistency across the machine width. The conventional headbox depends on their adjustable slice lip to control it, therefore the fiber orientation profile is changed accordingly. Only Module Jet can control the CD basis weight profile and the fiber orientation profile independently.Module Jet is better applied to gap former headbox and multi-layer headbox because of its simple top lip structure.The first Module Jet successfully started up at Munkedal PM 5 (Sweden) in January 1994, and then the order of Module Jet has been 15 units.

坪量プロファイルへのファジィ制御の適用

坪量プロファイルへのファジィ制御の適用

On the Approximation of a Deflection Curve by Force Actuators With Variable Spacing

In this paper we discuss a suboptimal method of approximating a desired deflection curve of a simple beam by a given number of force actuators. The spacing between the actuators is allowed to vary as a function of the deflection curve. The method is applied to an example of approximation of a deflection curve of the slice lip on a paper machine headbox for the control of the basis weight profile of paper. The approximation error with variable spacing is compared with that obtained when the spacing is not varied (uniformly-spaced actuators). Significant reduction in error is observed.

Utilizing a position-sensitive wire chamber in sheet density measurements

We present a novel wire chamber application of measuring paper basis weight utilizing a position-sensitive wire chamber as a detector for beta particles. Using a position-sensitive wire chamber with a thin entrance window offers the unique possibility of determining paper basis weight profile on a line instead of the presently used measurement by points. The required position resolution of ≈0.5 mm can be routinely achieved with a detector element of 5–10 cm, which is sufficient for laboratory-scale paper quality measurements. The measurement time depends on the required accuracies for basis weight and position as well as on the maximum count rate capability of the detector and can be made as short as a few minutes, which compares favourably with the present devices. We give a short presentation of the various aspects of paper measurements with beta particles in general and especially those concerning position-sensitive detectors in paper quality control. Furthermore, results from measurements made with prototype detectors are presented.

Ｘ線ＣＴスキャナによる巻取り内部の不均一性の解析

Paper rolls were analyzed nondestructively by a computerized tomographic (CT) system. The images of cross-sections of paper rolls were shown as faithfully as if they were observed by cutting them. The tomographic image density (CT value) of a cut paper sheet bundle was proportional to its sheet paper density.In CD profiles of CT values of paper rolls, each had a different CD profile. A paper roll wound at higher tension has a poor CD profile of CT values, which indicated internal stress concentrated locally in the roll. The macroscale MD profile of CT values coincided well with the basis weight profile. The longrange MD profile of CT values decreased gradually from a surface to a core of a paper roll, which indicated that internal stress decreased from the core to the surfce.