CN111203949B - Evaluation method for longitudinal dissociation performance of grinding piece of defibrator based on fractal theory - Google Patents

Evaluation method for longitudinal dissociation performance of grinding piece of defibrator based on fractal theory Download PDF

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CN111203949B
CN111203949B CN202010042727.1A CN202010042727A CN111203949B CN 111203949 B CN111203949 B CN 111203949B CN 202010042727 A CN202010042727 A CN 202010042727A CN 111203949 B CN111203949 B CN 111203949B
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CN111203949A (en
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许威
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Harbin University of Commerce
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B27—WORKING OR PRESERVING WOOD OR SIMILAR MATERIAL; NAILING OR STAPLING MACHINES IN GENERAL
    • B27L—REMOVING BARK OR VESTIGES OF BRANCHES; SPLITTING WOOD; MANUFACTURE OF VENEER, WOODEN STICKS, WOOD SHAVINGS, WOOD FIBRES OR WOOD POWDER
    • B27L11/00—Manufacture of wood shavings, chips, powder, or the like; Tools therefor
    • B27L11/08—Manufacture of wood shavings, chips, powder, or the like; Tools therefor of wood fibres, e.g. produced by tearing

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Abstract

The invention discloses a method for evaluating the longitudinal dissociation performance of a grinding disc of a defibrator based on a fractal theory, which belongs to the field of manufacturing of fiberboards and is provided aiming at the defects of short service life and low fiber quality of the conventional grinding disc, and the method comprises the following steps of collecting a wood raw material sample; sample screening, measurement of nominal length dimension and determination of grade; verifying the rationality of the nominal length size grading difference of the wood raw material measurement sample; determining a calculated length dimension for each acquisition zone measurement sample; establishing a regression equation of longitudinal morphological change of the wood raw material in the grinding area; calculating the longitudinal dissociation dimension of the wood raw material; calculating the mean value of the longitudinal dissociation dimensions of each pair of grinding wood raw materials; calculating the characteristic coefficient of the mean value of the longitudinal dissociation dimensions of the wood raw material; and balancing coefficient values according to the calculated longitudinal dissociation performance of the grinding sheet. The method makes up the defects of the existing evaluation method, provides technical support for the optimization design of the grinding sheet structure, is beneficial to improving the fiber separation quality, prolongs the service life of the grinding sheet and reduces the energy consumption.

Description

Evaluation method for longitudinal dissociation performance of grinding piece of defibrator based on fractal theory
The technical field is as follows:
the invention belongs to the technical field of fiberboard manufacturing, and particularly relates to a method for evaluating longitudinal dissociation performance of a grinding sheet of a defibrator based on a fractal theory.
Background art:
according to statistical data of the national forestry bureau, the yield of the fiber board in China is more than 6000 million cubic meters from 2013 to 2018, and the highest annual yield reaches 6651.22 million cubic meters (2016). The annual speed of fiberboard products in China is increased by 8.49 percent in the past decade, and the fiberboard products become the first major country for world fiberboard production.
The defibrator is the core equipment in the production of fiberboard, the defibrator grinding disc is the key component of the defibrator for directly separating wood fiber, and the grinding disc is the most important component of the defibrator, which directly affects the separation quality and the separation energy consumption of the fiber. The grinding performance of the grinding plate depends on the setting of the tooth-shaped structure parameters of the grinding areas of the grinding plate and the grinding progressive effect among the grinding areas. Taking three-zone (crushing zone, coarse grinding zone and fine grinding zone) grinding plate as an example, the crushing zone is used for carrying out first-step crushing on wood raw materials to crush the wood raw materials into coarse fibers, the coarse grinding zone is used for grinding the coarse fibers into fiber bundles with smaller size, and the fine grinding zone is used for further dissociating and finishing the fiber bundles to brooming the fiber bundles, and the fibers meet the monomer fibers or fine fibers required by fiberboard production in shape and size. The performance of the grinding sheet in the grinding process is directly reflected on the form change of the fiber raw material: if each grinding area can grind the fibers in each grinding area to a proper form, the wood raw materials enter the grinding areas until the wood raw materials are ground into monomer fibers or fine fibers meeting production requirements and leave the grinding areas, the fiber form change of each grinding area is uniform, the proportion of the fine fibers and the coarse fibers is low, the fiber quality is high, the abrasion of each grinding area of the grinding sheet is uniform, the service life of the grinding sheet is long, and the energy consumption in the grinding process is low. If the grinding zone is unable to grind the fibers to a suitable morphology, the grinding intensity of the other grinding zones is inevitably increased, the grinding teeth of the other grinding zones are excessively worn, the service life of the grinding plate is shortened, and the proportion of fine fibers or coarse fibers is also increased. Therefore, the good and bad grinding capability of a pair of grinding discs is evaluated, whether the tooth-shaped structural parameters of all the grinding disc regions are reasonably set or not is judged, and whether the progressive action among all the grinding regions of the grinding discs is reasonable or not is also judged. The conventional method for evaluating the grinding performance of the grinding sheet mainly comprises three methods of cutting length per second, specific load of a tooth edge and unit hot grinding power (specific energy consumption). Wherein, the cutting length per second and the specific load of the tooth edge are based on the length of the grinding teeth arranged on the grinding plate, and the transverse cutting action length of the grinding plate is theoretically calculated, so that the grinding strength of the grinding plate is evaluated. However, the influences of grinding parameters such as tooth groove width and tooth grinding inclination angle and the like and physical properties of wood raw materials on the transverse cutting action of the grinding teeth of the grinding plate are not considered, and the reasonability of the setting of the grinding structure parameters of each grinding area cannot be evaluated; the unit hot grinding power is only the power consumed when the absolutely dry fiber with the unit weight is quantitatively evaluated, so that the influence of the change of the tooth-shaped structure parameters on the performance of the grinding plate is indirectly evaluated. The three methods do not evaluate the reasonableness of tooth profile structural parameter design of each grinding area of the grinding sheet, and also do not evaluate the progressive effect among the grinding areas of the grinding sheet.
At present, the production technology of the fiber board in China is relatively lagged behind, the grinding plate production mainly adopts imitation, and the service life of the produced grinding plate and the quality of produced fibers are far lower than those of European and American countries. Therefore, a method for evaluating performance of a grinding sheet of a defibrator is urgently needed, and technical support is provided for optimization of structural design of the grinding sheet so as to guide the grinding sheet of the defibrator to perform optimization of tooth-shaped structural parameters, improve fiber production quality, prolong service life of the grinding sheet and reduce energy consumption of fiberboard production.
The invention content is as follows:
the invention provides a method for evaluating the longitudinal dissociation performance of a refiner plate of a defibrator based on a fractal theory, aiming at overcoming the defects of short service life and low quality of produced fibers of the conventional refiner plate, wherein the evaluation method can comprehensively evaluate the grinding longitudinal dissociation performance of the refiner plate of the defibrator, can make up the defect that the conventional evaluation method is separated from the actual production, provides technical support for the optimization design of the structure of the refiner plate, and is beneficial to improving the fiber separation quality, prolonging the service life of the refiner plate and reducing the energy consumption in the production process.
The technical scheme adopted by the invention is as follows: a fractal theory-based evaluation method for longitudinal dissociation performance of a grinding sheet of a defibrator comprises the following specific steps:
the method comprises the following steps: collecting wood raw material samples, setting more than two wood raw material sample collecting areas in each grinding subarea according to the size of a grinding sheet, and collecting the wood raw materials in tooth sockets in the collecting areas as samples;
step two: screening of wood raw material samples, measurement of nominal length dimensions and determination of grades
1) Screening wood raw material samples in the collection area:
2) measurement of nominal length dimensions of wood feedstock samples for each collection area:
3) determining the grade level difference of the nominal length dimension of the wood raw material measurement sample in each collection area:
step three: verifying the rationality of the nominal length size grading difference of the wood raw material measurement sample;
step four: determining a calculated length dimension for each acquisition zone measurement sample;
step five: establishing a regression equation of longitudinal morphological change of wood raw materials in the grinding area of the grinding plate, and performing linear regression on the calculated length size data of the measurement samples in the acquisition area in the grinding area of the grinding plate and the radial radius of the central position of the acquisition area;
step six: calculating the longitudinal dissociation dimension of the wood raw material;
step seven: repeating the first step to the sixth step, testing at least fiber samples collected on three pairs of grinding sheets under the same working condition, and calculating the mean value of the longitudinal dissociation dimensions of the wood raw materials of each pair of grinding sheets;
step eight: calculating to obtain a characteristic coefficient of the longitudinal dissociation dimension mean value of the wood raw material;
step nine: and judging the energy consumption of the longitudinal dissociation fibers of each grinding area of the grinding plate and the generated abrasion condition of the grinding plate according to the calculated coefficient value of the balance of the longitudinal dissociation performance of the grinding plate.
Preferably, in the first step, 3-8 wood raw material samples are arranged in each grinding subarea according to the size of the grinding sheetThe radial radius of the central position of each collecting area is RijThe collection zone then lies at a radial radius Rij-5～Rij+5 in the region of the circular ring.
Preferably, in the second step, the first step,
1) the specific process of screening the wood raw material sample in the collection area is as follows: firstly, respectively placing wood raw material samples collected from each collecting area into a test tube, then adding a proper amount of water into the test tube, and finally placing the test tube on an oscillator to fully untwist the wood raw material samples;
2) the specific process of measuring the nominal length dimension of the wood raw material sample in each acquisition area is as follows: firstly, selecting N wood raw material samples from wood raw material samples collected by each fully untwined collection area as measurement samples of the wood raw materials of the collection area, wherein N is more than or equal to 100 and can be divided by 10, and finally measuring the nominal length size of the wood raw material samples by using an optical microscope;
3) the formula for calculating the classification grade difference of the nominal length dimension of the wood raw material measurement sample in each collection area is as follows:
Figure BDA0002368306630000031
in the formula, deltaLijNominal length dimension grading step, L, of a measured sample of wood material for an ith grinding zone, jth acquisition zone, of a refiner platemaxijAnd LminijMeasuring the maximum and minimum values, m, of the nominal length dimension of the sample for the acquisition zoneLijMeasuring the fractional number of nominal length dimensions of the sample, m, for each area of collection of wood materialLij≥3，mLijTaking an integer.
Preferably, in the third step, the rationality of the nominal length dimension grading level difference of the wood raw material measurement sample is verified by the following formula:
Figure BDA0002368306630000032
in the formula, ρLijkGrinding for grinding the ithZone j acquisition zone wood material measurement sample nominal length dimension rating of kth (k 1, 2.., m.)Lij) The ratio of the number of measurement samples in a class division to the total number of measurement samples, NLijhMeasuring a h (h 1, 2,.., m) th nominal length dimension rating of the sample for the wood feedstock in the acquisition zoneLij) Number of measurement samples in the stage division, when rhoLij1And
Figure BDA0002368306630000033
when the concentration is between 5% and 15%, the value is deltaLijThe grading level difference is reasonably set.
Preferably, in the fourth step, the calculated length dimension of each measurement sample at the collection area is obtained by the following formula:
Figure BDA0002368306630000034
in the formula, LJijCalculating a length dimension, L, for a measured sample of wood material in a jth acquisition zone of an ith grinding sub-zone of a refiner plateminijIs the minimum value of the nominal length dimension of the fibers in the acquisition region, deltaLijThe acquisition zone measures the nominal length dimension of the sample by a fractional step, NLijkMeasuring a kth (k ═ 1, 2.. multidot.m., m., of a nominal length dimension scale of the sample for the acquisition zone wood feedstockLij) The number of measurement samples in the staging area.
Preferably, in the fifth step, a regression equation of the longitudinal form change of the wood raw material in the grinding section is obtained by the following formula:
ln(LYmax-LJij)＝kLiln(Rij)+CLi
in the formula, if LJijAnd RijK is the data of the ith grinding zone of the grinding sheetLiThe slope of the regression equation of the change of the length dimension of the wood raw material in the grinding zone i of the grinding sheet is given as LJijAnd RijK is data of the whole grinding area of the grinding sheetLiIs the slope, L, of the regression equation of the change in length of the wood material in the grinding zone of the abrasive sheetYmaxIs the average value of the maximum linear dimension of the wood raw material, CLiFitting the equation toObtaining the constant.
Preferably, in the sixth step, the longitudinal dissociation dimension of the wood raw material is obtained by the following formula:
DLi＝2kLi
in the formula, if kLiThe slope of the regression equation of the change of the length dimension of the wood raw material in the grinding zone i of the grinding sheet is DLiFor grinding the longitudinal dissociation dimension of wood raw material in the i-th grinding zone of the chip, if kLiIs the slope of regression equation of the change of length dimension of wood raw material in grinding section of grinding plateLiIs the longitudinal dissociation dimension of the wood raw material in the grinding area of the grinding plate.
Preferably, in the seventh step, the mean value of the longitudinal dissociation dimensions of each pair of grinding plate wood raw materials is obtained by the following formula:
Figure BDA0002368306630000041
in the formula, DLijA longitudinal dissociation dimension, D, of an ith grinding zone of the jth sub-grinding sheetLJiThe mean value of the longitudinal dissociation dimensions of the wood raw materials in the grinding area i of the grinding plate is shown, n is the measured grinding plate number, n is not less than 3, and n is an integer.
Preferably, in the step eight, the characteristic coefficient of mean value of longitudinal dissociation dimensions of the wood raw material is obtained by the following formula:
Figure BDA0002368306630000042
wherein n is the number of grinding zones of the grinding sheet, DLJ1，DLJ2，...，DLJnRespectively the mean value of the longitudinal dissociation dimensions, D, of the wood raw materials in each grinding area of the grinding sheetLJ0The mean value of the longitudinal dissociation dimensions of the wood raw materials in the grinding area of the grinding plate.
Preferably, in the ninth step, the coefficient of balance of the longitudinal dissociation performance of the grinding sheet is obtained by the following formula:
Figure BDA0002368306630000051
in the formula, DLJHThe coefficient is a coefficient for balancing the longitudinal dissociation performance of the grinding plate, the smaller the coefficient is, the more balanced the longitudinal dissociation performance of each grinding area of the grinding plate is, the energy consumption of the longitudinal dissociation fiber of each grinding area in the dissociation process of the wood raw material is balanced with the abrasion of the generated grinding plate, the quality of the fiber is good, otherwise, the larger the value is, the larger the difference is, the serious imbalance phenomenon of the energy consumption of the longitudinal dissociation fiber of each area and the abrasion of the generated grinding plate is, the service life of the grinding plate is short, and the quality of the fiber is poor.
The invention has the beneficial effects that:
1. the method for evaluating the grinding performance of the grinding sheet of the defibrator adopts a new idea, namely, a process of longitudinally grinding and dissociating the wood raw material by the grinding sheet with the same tooth-shaped structure parameter is regarded as a random process of fractal decomposition of the length dimension of the wood raw material, and a change rule of the fractal decomposition of the length dimension of the wood raw material is completely determined by the tooth-shaped structure parameter of the grinding sheet. The evaluation is carried out based on data for measuring the length dimension change of the wood raw material, and the fractal decomposition characteristics of the data are mainly determined by the parameters of the tooth-shaped structure of the grinding sheet. The evaluation method can evaluate the overall reasonability of the tooth-shaped structure parameter setting of the grinding sheet, and can evaluate the reasonability of the tooth-shaped structure parameter setting of each grinding area of the grinding sheet, the coupling effect between the tooth-shaped structure parameters of the grinding sheet and the progressive relation of the longitudinal grinding performance of each grinding area of the grinding sheet, so that the grinding longitudinal dissociation performance of the grinding sheet is comprehensively evaluated.
2. The evaluation method adopted by the invention can make up the defect that the existing evaluation method is separated from the actual production, provides technical support for the optimization design of the grinding sheet structure, is beneficial to improving the fiber separation quality, prolonging the service life of the grinding sheet of the defibrator and reducing the energy consumption in the production process.
The specific implementation mode is as follows:
the invention relates to a fractal theory-based evaluation method for longitudinal dissociation performance of a grinding sheet of a defibrator, which comprises the following steps:
the method comprises the following steps: collecting wood raw material sample
3-8 wood raw material sample collection areas are arranged in each grinding subarea according to the size of the grinding sheet, and the radial radius of the central position of each collection area is RijThe collection zone then lies at a radial radius Rij-5～RijCollecting the wood raw material in the tooth socket in the collecting area as a sample in the circular ring area of + 5;
step two: wood raw material sample screening, nominal length dimension measurement and classification
1) Screening wood raw material samples in a collection area: respectively placing the wood raw material samples collected from each collecting area into test tubes, adding a proper amount of water into the test tubes, and then placing the test tubes on an oscillator to fully untwist the wood raw material samples;
2) measurement of nominal length dimensions of wood feedstock samples at each collection area: respectively selecting N wood raw material samples from the wood raw material samples collected from each fully untwined collection area as measurement samples of the wood raw materials in the collection area, wherein N is more than or equal to 100 and can be divided by 10, and measuring the nominal length size of the wood raw material samples by using an optical microscope;
3) determining the grade level difference of the nominal length dimension of the wood raw material measurement sample in each collection area:
Figure BDA0002368306630000061
in the formula, deltaLijNominal length dimension grading step, L, of a measured sample of wood material for an ith grinding zone, jth acquisition zone, of a refiner platemaxijAnd LminijMeasuring the maximum and minimum values, m, of the nominal length dimension of the sample for the acquisition zoneLijMeasuring the fractional number of nominal length dimensions of the sample, m, for each area of collection of wood materialLij≥3，mLijTaking an integer;
step three: verifying the rationality of the nominal length dimension grading difference of the wood raw material measurement sample
Figure BDA0002368306630000062
In the formula, ρLijkK (k 1, 2,.. m., m) th nominal length dimension classification of measured sample of wood raw material for grinding disc of ith grinding zone and jth acquisition zoneLij) The ratio of the number of measurement samples in a class division to the total number of measurement samples, NLijhMeasuring a h (h 1, 2,.., m) th nominal length dimension rating of the sample for the wood feedstock in the acquisition zoneLij) Number of measurement samples in the stage division, when rhoLij1And
Figure BDA0002368306630000063
when the concentration is between 5% and 15%, the value is deltaLijThe grading level difference is reasonably set;
step four: determining a calculated length dimension of a measurement sample for each acquisition zone
Figure BDA0002368306630000064
In the formula, LJijCalculating a length dimension, L, for a measured sample of wood material in a jth acquisition zone of an ith grinding sub-zone of a refiner plateminijIs the minimum value of the nominal length dimension of the fibers in the acquisition region, deltaLijThe acquisition zone measures the nominal length dimension of the sample by a fractional step, NLijkMeasuring a kth (k ═ 1, 2.. multidot.m., m., of a nominal length dimension scale of the sample for the acquisition zone wood feedstockLij) The number of measurement samples in a staging area;
step five: establishment of regression equation of longitudinal morphological change of wood raw material in grinding area of grinding sheet
Data on calculated length of a measured sample in an acquisition zone of a grinding plate and a radial radius R of the center position of the acquisition zoneijPerforming linear regression to obtain a regression equation of the length dimension change of the wood raw material in the grinding area of the grinding plate as follows:
ln(LYmax-LJij)＝kLiln(Rij)+CLi
in the formula, if LJijAnd RijK is the data of the ith grinding zone of the grinding sheetLiFor grinding the length dimension of wood raw material in the i-th grinding zone of the sheetSlope of the equation if LJijAnd RijK is data of the whole grinding area of the grinding sheetLiIs the slope, L, of the regression equation of the change in length of the wood material in the grinding zone of the abrasive sheetYmaxIs the average value of the maximum linear dimension of the wood raw material, CLiFitting the obtained constants for each regression equation;
step six: calculating the longitudinal dissociation dimension of wood raw material
DLi＝2kLi
In the formula, if kLiThe slope of the regression equation of the change of the length dimension of the wood raw material in the grinding zone i of the grinding sheet is DLiFor grinding the longitudinal dissociation dimension of wood raw material in the i-th grinding zone of the chip, if kLiIs the slope of regression equation of the change of length dimension of wood raw material in grinding section of grinding plateLiThe longitudinal dissociation dimension of the wood raw material in the grinding area is set;
step seven: calculating the mean value of the longitudinal dissociation dimensions of the wood raw material
Repeating the first step to the sixth step, at least testing the fiber samples collected on three pairs of grinding sheets under the same working condition, and calculating the longitudinal dissociation dimension D of the wood raw material of each pair of grinding sheetsLiAnd calculating the average value:
Figure BDA0002368306630000071
in the formula, DLijA longitudinal dissociation dimension, D, of an ith grinding zone of the jth sub-grinding sheetLJiGrinding the mean value of the longitudinal dissociation dimensions of the wood raw materials in the ith grinding area of the grinding plate, wherein n is the measured grinding plate number, n is more than or equal to 3, and n is an integer;
step eight: calculating the characteristic coefficient of the mean value of the longitudinal dissociation dimensions of the wood raw material
1) Calculating the characteristic coefficient of the mean value of the longitudinal dissociation dimensions of the wood raw materials:
Figure BDA0002368306630000072
wherein n is the number of grinding zones of the grinding sheet, DLJ1，DLJ2，...，DLJnRespectively the mean value of the longitudinal dissociation dimensions, D, of the wood raw materials in each grinding area of the grinding sheetLJ0The mean value of the longitudinal dissociation dimensions of the wood raw materials in the grinding area of the grinding plate;
step nine: calculating the equilibrium coefficient of the longitudinal dissociation performance of the abrasive disc
Figure BDA0002368306630000073
In the formula, DLJHThe coefficient is a coefficient for balancing the longitudinal dissociation performance of the grinding plate, the smaller the coefficient is, the more balanced the longitudinal dissociation performance of each grinding area of the grinding plate is, the energy consumption of the longitudinal dissociation fiber of each grinding area in the dissociation process of the wood raw material is balanced with the abrasion of the generated grinding plate, the quality of the fiber is good, otherwise, the larger the value is, the larger the difference is, the serious imbalance phenomenon of the energy consumption of the longitudinal dissociation fiber of each area and the abrasion of the generated grinding plate is, the service life of the grinding plate is short, and the quality of the fiber is poor.
The method for evaluating the grinding performance of the grinding sheet of the defibrator adopts a new idea, namely, a process of longitudinally grinding and dissociating wood raw materials by the grinding sheet with the same tooth-shaped structure parameter is regarded as a random process of fractal decomposition of the length and the size of the wood raw materials, and a change rule of the fractal decomposition of the length and the size of the wood raw materials is completely determined by the tooth-shaped structure parameter of the grinding sheet. The evaluation is carried out based on data for measuring the length dimension change of the wood raw material, and the fractal decomposition characteristics of the data are mainly determined by the parameters of the tooth-shaped structure of the grinding sheet. The evaluation method can evaluate the overall reasonability of the tooth-shaped structure parameter setting of the grinding sheet, and can evaluate the reasonability of the tooth-shaped structure parameter setting of each grinding area of the grinding sheet, the coupling effect between the tooth-shaped structure parameters of the grinding sheet and the progressive relation of the longitudinal grinding performance of each grinding area of the grinding sheet, so that the grinding longitudinal dissociation performance of the grinding sheet is comprehensively evaluated. The evaluation method can make up the defect that the existing evaluation method is separated from the actual production, provides technical support for the optimization design of the grinding sheet structure, is beneficial to improving the fiber separation quality, prolonging the service life of the grinding sheet of the defibrator and reducing the energy consumption in the production process.
The above description is only a preferred embodiment of the present invention, and these embodiments are based on different implementations of the present invention, and the scope of the present invention is not limited thereto, and any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope of the present invention are included in the scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the claims.

Claims (10)

1. A fractal theory-based evaluation method for longitudinal dissociation performance of a grinding sheet of a defibrator is characterized by comprising the following specific steps:
the method comprises the following steps: collecting wood raw material samples, setting more than two wood raw material sample collecting areas in each grinding subarea according to the size of a grinding sheet, and collecting the wood raw materials in tooth sockets in the collecting areas as samples;
step two: screening of wood raw material samples, measurement of nominal length dimensions and determination of grades
1) Screening wood raw material samples in the collection area:
2) measurement of nominal length dimensions of wood feedstock samples for each collection area:
3) determining the grade level difference of the nominal length dimension of the wood raw material measurement sample in each collection area:
step three: verifying the rationality of the nominal length size grading difference of the wood raw material measurement sample;
step four: determining a calculated length dimension for each acquisition zone measurement sample;
step five: establishing a regression equation of longitudinal morphological change of wood raw materials in the grinding area of the grinding plate, and performing linear regression on the calculated length size data of the measurement samples in the acquisition area in the grinding area of the grinding plate and the radial radius of the central position of the acquisition area;
step six: calculating the longitudinal dissociation dimension of the wood raw material;
step seven: repeating the first step to the sixth step, testing at least wood raw materials collected on three pairs of grinding sheets under the same working condition, and calculating the mean value of the longitudinal dissociation dimensions of the wood raw materials of each pair of grinding sheets;
step eight: calculating to obtain a characteristic coefficient of the longitudinal dissociation dimension mean value of the wood raw material;
step nine: and judging the energy consumption of the longitudinal dissociation fibers of each grinding area of the grinding plate and the generated abrasion condition of the grinding plate according to the calculated coefficient value of the balance of the longitudinal dissociation performance of the grinding plate.
2. The evaluation method for the longitudinal dissociation performance of the grinding sheet of the defibrator based on the fractal theory as claimed in claim 1, wherein: in the first step, 3-8 wood raw material sample collecting areas are arranged in each grinding subarea according to the size of the grinding sheet, and the radial radius of the central position of each collecting area is RijThe collection zone then lies at a radial radius Rij-5～Rij+5 in the region of the circular ring.
3. The evaluation method for the longitudinal dissociation performance of the grinding sheet of the defibrator based on the fractal theory as claimed in claim 2, wherein: in the second step, the first step is carried out,
1) the specific process of screening the wood raw material sample in the collection area is as follows: firstly, respectively placing wood raw material samples collected from each collecting area into a test tube, then adding a proper amount of water into the test tube, and finally placing the test tube on an oscillator to fully untwist the wood raw material samples;
2) the specific process of measuring the nominal length dimension of the wood raw material sample in each acquisition area is as follows: firstly, selecting N wood raw material samples from wood raw material samples collected by each fully untwined collection area as measurement samples of the wood raw materials of the collection areas, wherein N is more than or equal to 100 and can be divided by 10, and finally measuring the nominal length size of the wood raw materials by using an optical microscope;
3) the formula for calculating the classification grade difference of the nominal length dimension of the wood raw material measurement sample in each collection area is as follows:
Figure FDA0003041749670000021
in the formula, deltaLijName of wood material measurement sample of j acquisition zone of i grinding sub-zone for grinding abrasive sheetLength-limited size grading difference, LmaxijAnd LminijMeasuring maximum and minimum values of nominal length dimension of sample, m, for acquisition zone respectivelyLijMeasuring the fractional number of nominal length dimensions of the sample, m, for each area of collection of wood materialLij≥3，mLijTaking an integer.
4. The evaluation method for the longitudinal dissociation performance of the grinding sheet of the defibrator based on the fractal theory as claimed in claim 3, wherein: in the third step, the rationality of the nominal length size grading difference of the wood raw material measurement sample is verified through the following formula:
Figure FDA0003041749670000022
in the formula, ρLijkK (k 1, 2,.. m., m) th nominal length dimension classification of measured sample of wood raw material for grinding disc of ith grinding zone and jth acquisition zoneLij) The ratio of the number of measurement samples in a class division to the total number of measurement samples, NLijhH (1, 2,.. multidot.m.Lij) Number of measurement samples in the stage division, when rhoLij1And
Figure FDA0003041749670000023
when the concentration is between 5% and 15%, the value is deltaLijThe grading level difference is reasonably set.
5. A fractal theory-based evaluation method for the longitudinal dissociation performance of grinding sheets of a defibrator according to any one of claims 1 to 4, wherein: in the fourth step, the calculated length size of each measurement sample of the collection area is obtained by the following formula:
Figure FDA0003041749670000024
in the formula, LJijWood of jth acquisition zone of ith grinding zone for abrasive sheetCalculated length dimension, L, of material measurement sampleminijIs the minimum value of the nominal length dimension of the fibers in the acquisition region, deltaLijNominal length dimension of sample measured in collection area, grade difference, NLijkMeasuring a kth (k ═ 1, 2...., m.) of a sample nominal length dimension scale for the acquisition zone wood feedstockLij) The number of measurement samples in the staging area.
6. The evaluation method for the longitudinal dissociation performance of the grinding sheet of the defibrator based on the fractal theory as claimed in claim 5, wherein: in the fifth step, a regression equation of the longitudinal form change of the wood raw material in the grinding section grinding area is obtained through the following formula:
ln(LYmax-LJij)＝kLiln(Rij)+CLi
in the formula, if LJijAnd RijK is the data of the ith grinding zone of the grinding sheetLiThe slope of the regression equation of the change of the length dimension of the wood raw material in the grinding zone i of the grinding sheet is given as LJijAnd RijK is data of the whole grinding area of the grinding sheetLiIs the slope, L, of the regression equation of the change in length of the wood material in the grinding zone of the abrasive sheetYmaxIs the average value of the maximum linear dimension of the wood raw material, CLiThe resulting constants were fitted to each regression equation.
7. The evaluation method for the longitudinal dissociation performance of the grinding sheet of the defibrator based on the fractal theory as claimed in claim 6, wherein: in the sixth step, the longitudinal dissociation dimension of the wood raw material is obtained through the following formula:
DLi＝2kLi
in the formula, if kLiThe slope of the regression equation of the change of the length dimension of the wood raw material in the grinding zone i of the grinding sheet is DLiFor grinding the longitudinal dissociation dimension of wood raw material in the i-th grinding zone of the chip, if kLiIs the slope of regression equation of the change of length dimension of wood raw material in grinding section of grinding plateLiIs the longitudinal dissociation dimension of the wood raw material in the grinding area of the grinding plate.
8. The evaluation method for the longitudinal dissociation performance of the grinding sheet of the defibrator based on the fractal theory as claimed in claim 1, wherein: in the seventh step, the mean value of the longitudinal dissociation dimensions of each pair of grinding sheet wood raw materials is obtained through the following formula:
Figure FDA0003041749670000031
in the formula, DLijA longitudinal dissociation dimension, D, of an ith grinding zone of the jth sub-grinding sheetLJiThe mean value of the longitudinal dissociation dimensions of the wood raw materials in the grinding area i of the grinding plate is shown, n is the measured grinding plate number, n is not less than 3, and n is an integer.
9. The evaluation method for the longitudinal dissociation performance of the grinding sheet of the defibrator based on the fractal theory as claimed in claim 1, wherein: in the step eight, the characteristic coefficient of the mean value of the longitudinal dissociation dimensions of the wood raw material is obtained through the following formula:
Figure FDA0003041749670000032
wherein n is the number of grinding zones of the grinding sheet, DLJ1，DLJ2，...，DLJnRespectively the mean value of the longitudinal dissociation dimensions, D, of the wood raw materials in each grinding area of the grinding sheetLJ0The mean value of the longitudinal dissociation dimensions of the wood raw materials in the grinding area of the grinding plate.
10. A fractal theory-based evaluation method for longitudinal dissociation performance of refiner plates according to any one of claims 1, 2, 3, 4 or 9, wherein: in the ninth step, the coefficient of equilibrium of the longitudinal dissociation performance of the abrasive disc is obtained through the following formula:
Figure FDA0003041749670000033
in the formula, DLJHThe lower the coefficient of the balance of the longitudinal dissociation performance of the grinding plate, the more balanced the longitudinal dissociation performance of each grinding area of the grinding plate is proved, the energy consumption of the longitudinal dissociation fiber of each grinding area in the dissociation process of the wood raw material is balanced with the abrasion of the generated grinding plate, the fiber quality is good, otherwise, if the coefficient of the balance of the longitudinal dissociation performance of the grinding plate is higher, the difference of the longitudinal dissociation performance of each grinding area of the grinding plate is proved to be large, the imbalance phenomenon of the energy consumption of the longitudinal dissociation fiber of each area and the abrasion of the generated grinding plate is serious, the service life of the grinding plate is short, and the fiber quality is poor.
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