AU5076599A - Method to predict and/or control the strength properties of foil-like material - Google Patents
Method to predict and/or control the strength properties of foil-like material Download PDFInfo
- Publication number
- AU5076599A AU5076599A AU50765/99A AU5076599A AU5076599A AU 5076599 A AU5076599 A AU 5076599A AU 50765/99 A AU50765/99 A AU 50765/99A AU 5076599 A AU5076599 A AU 5076599A AU 5076599 A AU5076599 A AU 5076599A
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- AU
- Australia
- Prior art keywords
- measurements
- foil
- local
- strength
- stiffness
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Abandoned
Links
- 238000000034 method Methods 0.000 title claims description 22
- 239000000463 material Substances 0.000 title claims description 20
- 238000005259 measurement Methods 0.000 claims description 22
- 238000005452 bending Methods 0.000 claims description 4
- 238000004519 manufacturing process Methods 0.000 claims description 4
- 238000004886 process control Methods 0.000 claims description 2
- 238000003908 quality control method Methods 0.000 claims description 2
- 239000011888 foil Substances 0.000 claims 1
- 238000010009 beating Methods 0.000 description 8
- 238000010586 diagram Methods 0.000 description 4
- 238000002604 ultrasonography Methods 0.000 description 4
- 238000001035 drying Methods 0.000 description 3
- 238000000691 measurement method Methods 0.000 description 2
- 230000015572 biosynthetic process Effects 0.000 description 1
- 230000006835 compression Effects 0.000 description 1
- 238000007906 compression Methods 0.000 description 1
- 230000001419 dependent effect Effects 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000002474 experimental method Methods 0.000 description 1
- 239000012467 final product Substances 0.000 description 1
- 230000003287 optical effect Effects 0.000 description 1
- 230000000452 restraining effect Effects 0.000 description 1
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N3/00—Investigating strength properties of solid materials by application of mechanical stress
- G01N3/08—Investigating strength properties of solid materials by application of mechanical stress by applying steady tensile or compressive forces
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N33/00—Investigating or analysing materials by specific methods not covered by groups G01N1/00 - G01N31/00
- G01N33/34—Paper
- G01N33/346—Paper sheets
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N2203/00—Investigating strength properties of solid materials by application of mechanical stress
- G01N2203/02—Details not specific for a particular testing method
- G01N2203/026—Specifications of the specimen
- G01N2203/0262—Shape of the specimen
- G01N2203/0278—Thin specimens
- G01N2203/0282—Two dimensional, e.g. tapes, webs, sheets, strips, disks or membranes
Landscapes
- Chemical & Material Sciences (AREA)
- Health & Medical Sciences (AREA)
- Life Sciences & Earth Sciences (AREA)
- General Health & Medical Sciences (AREA)
- Analytical Chemistry (AREA)
- Biochemistry (AREA)
- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Immunology (AREA)
- Pathology (AREA)
- Engineering & Computer Science (AREA)
- Food Science & Technology (AREA)
- Medicinal Chemistry (AREA)
- Paper (AREA)
- Investigating Strength Of Materials By Application Of Mechanical Stress (AREA)
Description
WO 00/07010 PCT/SE99/01237 Method to predict and/or control the strength properties of a foil-like material The present invention relates to a method to predict and/or control the strength properties of a foil-like material in relation to machinery and processes for manufacturing this material. 5 It especially relates to properties with regard to the tensile strength and tensile strength index (tensile index) of the foil-like material in question. The invention is based on the use of and access to statistical information regarding local mechanical properties, especially local tensile stiffness and local tensile stiffness index. When the foil-like material is paper, a specially interesting characteristic of the invention is that it 10 makes it possible to achieve a suitable trade off between the tensile strength of the paper and the variation in other important measured properties of paper. Unfortunately, it is not always possible to simultaneously achieve the sought after minimum variations or the desired levels of key parameters, such as local tensile stiffness and local basis weight. For example, the tensile strength is not always greatest 15 when variations in basis weight are minimised. In practice, this means that a compromise must be made. In many processes for manufacturing paper, it would thus be of greatest importance if the mechanical strength of the paper could be frequently predicted to allow rapid control measures to be taken and also to make it possible to achieve the desired quality in the final product. 20 Today, the tensile strength of paper is predicted by means of models that are based on information regarding the mean value of modules of elasticity that are measured in different directions in the material. These modules of elasticity are increasingly often estimated on the basis of measurements that give the phase velocity of ultrasound in the material. Predicting tensile strength based on information about the 25 spatial variations in basis weight of paper, such as the formation number, have also been tested in practice but have had only limited success. The lack of success regarding the desired prediction is not surprising in the light of the discoveries on which the present invention is based. The spatial resolution, which is normally 10 cm for the ultrasound measurements that are carried out on moving 30 paper webs, is not sufficient in relation to the resolution that, according to the invention, would have been required. It has been shown that a spatial resolution in the order of millimetres gives a very good result. In addition, theoretical calculations and WO 00/07010 PCT/SE99/01237 2 measurements show that the relation between the measured wave velocity for ultrasound and the module of elasticity of the material in question can vary when the process conditions change, such as variations in the beating of the pulp; see Fig. 1. It should be seen that the variation shown in Fig. 1 is significant in connection with control 5 applications of the type referred to. When one attempts to use data that give variations in local basis weight to achieve the desired prediction, one encounters the problem that the local basis weight does not always reflect the important local mechanical properties. In accordance with the principles of the invention it now becomes possible to realize a method of the type mentioned in the introduction by the measurements being 10 performed locally on the foil-like material and with a high spatial resolution - from 20 mm and less - to obtain a mean value and variation regarding at least one local mechanical property of the foil-like material, whereby the strength value or control signal worked out from the measurement results obtained is used to achieve the strength prediction and/or the process and quality control desired. 15 Different advantageous embodiments of the new method are evident from the non-independent claims 2-8. In this way, the said measurements can be of the direct and/or indirect measurement type. In particular, an adjustment of the strength value and/or control signal is made as a result of structural differences in the foil-like material based on local measurements of at least one further mechanical property, preferably 20 bending stiffness. The measurements are preferably carried out on a mm-scale with a high frequency of repetition in relation to the dynamics of the process. The foil-like material comprises paper especially. At least one of the local mechanical properties is measured in what is per se a known manner, especially by means of the arrangement described in US 5 361 638. 25 The invention will now be described in more detail below with reference to the enclosed drawings wherein: Fig. 1 shows in diagram form the relation between a standard test and an ultrasound test on paper at different indices of tensional stiffness and beating levels for pulp; 30 Fig. 2 shows in diagram form the relation between mean values of index of tensional stiffness and index of tensional strength for different levels of beating; WO 00/07010 PCT/SE99/01237 3 Fig. 3 shows in diagram form the relation between measured index of tensional strength and, according to the invention, the predicted index of tensional strength for different levels of beating; Fig. 4 shows in diagram form the relation between strength quotient and 5 stiffness quotient at varying conditions of orientation (81 samples, 3 forming units and 3 different pulps). The new observation on which the present invention is based is that successful prediction of the strength properties of paper, for example tensile strength, requires the use of data for both the mean value and the statistical variations in the local 10 tensile stiffness (Its) and/or the local tensile stiffness index (ltsi) measured with a spatial resolution at the millimetre level. The statistical variations can be expressed by the measured maximum and minimum values, the standard deviation c-, the coefficient of variation CV or a number of other parameters that can be obtained from the statistical frequency function for the 15 measured local mechanical properties. (Information regarding the local variations in tensile stiffness index can be obtained from the local tensile stiffness data if the local basis weights have also been measured at the same locations). Until very recently no measurement method has been available that has been able to provide the type of local data that are required for the said prediction. 20 Fortunately, it has now become possible to obtain the required data by utilising a new arrangement that is described in US 5 361 638. As already mentioned, the type of predictive model that we have found to be very useful is based on information about both mean values and statistical variations in local tensile stiffness and/or local tensile stiffness index measured on a millimetre scale. 25 In accordance with the principles of the invention, the mean value m of the tensile stiffness and the tensile stiffness index firstly give a value of the upper limit of the tensile strength that can be achieved. This upper limit can only be achieved if the paper has a completely even structure, i.e. if it lacks disturbing local variations. In accordance with the principles of the invention, variations in local tensile stiffness, secondly, give 30 rise to a spatially variable strain in the paper that will reduce the tensile strength of the paper to below the said upper limit.
WO 00/07010 PCT/SE99/01237 4 There are significant variations in local tensile stiffness measured on a millimetre scale in commercially manufactured paper. To obtain a good predictive result, it is therefore very important to take account of these local variations, whose amplitude varies with varying conditions of production. The relation between measured mean 5 values of tensile stiffness and tensile strength will vary significantly with, for example, beating level (beating of the pulp) if the local variations are not taken into account, see Fig. 2. Results of prediction experiments that are based on data obtained by means of the arrangement described in US 5 361 638 are shown in Fig. 3. The contents of the 10 said US patent, which in this way contributes to the realisation of the present invention in an ingenious manner, are therefore intended to be included by reference in the present patent matter. By use of a prediction model according to the invention and according to what is evident in detail from the following equation, a very good prediction (r 2 = 0.997) is obtained. This result has been obtained under significantly variable process conditions, 15 in this case varying beating levels (degree of beating). Tensile strength = f(m, a)ats; = const.* m" 5 /(1 + a /m) It is known that structural differences in the sheet as a result of the varying 20 degree of orientation (MD/CD ratio; where MD is the direction of the machinery and CD is the transverse direction) as well as varying tension (restraining force) during the drying of the paper affect the relation between measured tensile stiffness and tensile strength. With the aid of the arrangement described in US 5 361 638, data can be obtained that allow compensation for changes as a result of structural differences. 25 Examples of data that can be obtained with the measurement method are local stiffness in different directions (MD, CD and ZD) in the paper, i.e. tensile stiffness and bending stiffness in MD and CD as well as compressional stiffness in the thickness direction ZD. The result that we have obtained when evaluating experimental data shows that when orientation increases (increasing MD/CD ratio), the tensile strength in MD in 30 relation to the tensile strength in CD will increase somewhat more than the tensile stiffness in MD in relation to the tensile stiffness in CD; see Fig. 4. With knowledge of this relationship and the actual tensile stiffness in the said directions, the influence of a WO 00/07010 PCT/SE99/01237 5 varying MD/CD relationship can be compensated by the introduction of a function g of the stiffness in MD and CD, which gives: Tensile strength index = f* g(stiffness-MD, stiffness-CD) 5 It is widely known that the tensile stiffness increases to a larger extent than the tensile strength with increased drying tension. At the same time, the relation between stiffnesses measured in different directions in the paper changes. Thus, with the present invention, even this effect can be compensated for, in this case by the introduction of a 10 function h of the stiffnesses in MD, CD and ZD, i.e. in the machine, transverse and thickness directions. When determining the tensile strength of paper with different levels of local variations in stiffness, varying MD/CD ratios and different tensions during drying the following predictive function is utilised: 15 Tensile strength index = f* g *h(stiffness-MD, stiffness-CD, stiffness-ZD) The present invention can also lead to an improved prediction of the tensile strength of a material on the basis of indirect measurements. In these cases, the method is complemented by utilising a relation between data from a number of other local 20 measurements and the local tensile stiffness and/or the local tensile stiffness index, which are required to obtain a better prediction. This naturally applies if a relation can be confirmed at the actual process conditions. Examples of indirect measurements that may be used (separately or in combination) to generate data for this type of prediction are local basis weight, local optical density and local thickness of the paper. 25 Finally, it is probable that other strength properties of paper, for example tear strength and compression strength, are similarly dependent on variations in the local mechanical properties, such as the local stiffness (in the plane and/or the thickness direction) and the local rigidity to bending, i.e. properties that are measured with a high spatial resolution. 30 ------------
Claims (8)
1. Method to predict and/or control the strength properties of a foil-like material in relation to machinery and processes for manufacturing this material, c h a r a c t e r i z e d in that measurements are performed locally on the foil-like 5 material and with a high spatial resolution - from 20 mm and less - to obtain a mean value and variation regarding at least one local mechanical property of the foil-like material, whereby the strength value or control signal worked out from the measurement results obtained is used to achieve the strength prediction and/or the process and quality control desired. 10
2. Method according to claim 1, c h a r a c t e r i z e d in that the said measurements are direct measurements.
3. Method according to claim 1, c h a r a c t e r i z e d in that the said measurements are 15 indirect measurements.
4. Method according to claim 1, c h a r a c t e r i z e d in that the said measurements are both direct and indirect measurements. 20
5. Method according to any of claims 1-4, c h a r a c t e r i z e d in that an adjustment of the strength value and/or control signal is made as a result of structural differences in the foil-like material based on local measurements of at least one further mechanical property, preferably rigidity to bending. 25
6. Method according to any of the previous claims, c h a r a c t e r i z e d in that measurements are carried out on a mm-scale with a high frequency of repetition in relation to the dynamics of the process.
7. Method according to any of the previous claims, c h a r a c t e r i z e d in that the foil 30 like material comprises paper. WO 00/07010 PCT/SE99/01237 7
8. Method according to any of the claims 1, 2 and 4-7, c h a r a c t e r i z e d in that least one of the local mechanical properties is measured in what is per se a known manner by means of the arrangement described in US 5 361 638.
Applications Claiming Priority (3)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
SE9802652A SE514572C2 (en) | 1998-07-31 | 1998-07-31 | A method for predicting and / or controlling the strength properties of foil-like materials |
SE9802652 | 1998-07-31 | ||
PCT/SE1999/001237 WO2000007010A1 (en) | 1998-07-31 | 1999-07-07 | Method to predict and/or control the strength properties of a foil-like material |
Publications (1)
Publication Number | Publication Date |
---|---|
AU5076599A true AU5076599A (en) | 2000-02-21 |
Family
ID=20412182
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
AU50765/99A Abandoned AU5076599A (en) | 1998-07-31 | 1999-07-07 | Method to predict and/or control the strength properties of foil-like material |
Country Status (5)
Country | Link |
---|---|
EP (1) | EP1101109A1 (en) |
AU (1) | AU5076599A (en) |
CA (1) | CA2337335A1 (en) |
SE (1) | SE514572C2 (en) |
WO (1) | WO2000007010A1 (en) |
Families Citing this family (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
GB2621852A (en) | 2022-08-24 | 2024-02-28 | Siemens Energy Global Gmbh & Co Kg | Turbine vane for a gas turbine |
Family Cites Families (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
CA919937A (en) * | 1969-11-24 | 1973-01-30 | J. E. C. Stringer Peter | Paper machine tension tester |
US4936141A (en) * | 1987-10-06 | 1990-06-26 | Measurex Corporation | On-line paper sheet strength determination method and device |
US5361638A (en) * | 1990-03-30 | 1994-11-08 | Stfi | Arrangement for measuring mechanical properties of a foil material through use of an excitation unit that includes a laser |
SE464597B (en) * | 1990-03-30 | 1991-05-13 | Svenska Traeforskningsinst | DEVICE FOR MEASURING MECHANICAL PROPERTIES, SUCH AS STRENGTH AND WEIGHT, OF FOLI-LIKE MATERIALS, EXCEPT PAPER |
US5814730A (en) * | 1996-06-10 | 1998-09-29 | Institute Of Paper Science And Technology And Georgia Institute Of Technology | Material characteristic testing method and apparatus using interferometry to detect ultrasonic signals in a web |
-
1998
- 1998-07-31 SE SE9802652A patent/SE514572C2/en not_active IP Right Cessation
-
1999
- 1999-07-07 AU AU50765/99A patent/AU5076599A/en not_active Abandoned
- 1999-07-07 EP EP99935247A patent/EP1101109A1/en not_active Withdrawn
- 1999-07-07 WO PCT/SE1999/001237 patent/WO2000007010A1/en active Application Filing
- 1999-07-07 CA CA002337335A patent/CA2337335A1/en not_active Abandoned
Also Published As
Publication number | Publication date |
---|---|
EP1101109A1 (en) | 2001-05-23 |
SE9802652D0 (en) | 1998-07-31 |
CA2337335A1 (en) | 2000-02-10 |
SE9802652L (en) | 2000-02-01 |
SE514572C2 (en) | 2001-03-12 |
WO2000007010A1 (en) | 2000-02-10 |
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Legal Events
Date | Code | Title | Description |
---|---|---|---|
MK1 | Application lapsed section 142(2)(a) - no request for examination in relevant period |