CN113481761A - Preparation process based on low-basis-weight high-strength coated white board paper - Google Patents

Preparation process based on low-basis-weight high-strength coated white board paper Download PDF

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CN113481761A
CN113481761A CN202110418996.8A CN202110418996A CN113481761A CN 113481761 A CN113481761 A CN 113481761A CN 202110418996 A CN202110418996 A CN 202110418996A CN 113481761 A CN113481761 A CN 113481761A
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paper
thickness
area
abnormal
measuring
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CN113481761B (en
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胡鑫
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Zhejiang Jinhua Dingding Industrial Co ltd
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Zhejiang Jinhua Dingding Industrial Co ltd
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    • D—TEXTILES; PAPER
    • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
    • D21H—PULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
    • D21H27/00—Special paper not otherwise provided for, e.g. made by multi-step processes
    • D21H27/30—Multi-ply
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B37/00—Methods or apparatus for laminating, e.g. by curing or by ultrasonic bonding
    • B32B37/12—Methods or apparatus for laminating, e.g. by curing or by ultrasonic bonding characterised by using adhesives
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B38/00—Ancillary operations in connection with laminating processes
    • B32B38/16—Drying; Softening; Cleaning
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B41/00—Arrangements for controlling or monitoring lamination processes; Safety arrangements
    • D—TEXTILES; PAPER
    • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
    • D21F—PAPER-MAKING MACHINES; METHODS OF PRODUCING PAPER THEREON
    • D21F11/00—Processes for making continuous lengths of paper, or of cardboard, or of wet web for fibre board production, on paper-making machines
    • D21F11/02—Processes for making continuous lengths of paper, or of cardboard, or of wet web for fibre board production, on paper-making machines of the Fourdrinier type
    • D21F11/04—Processes for making continuous lengths of paper, or of cardboard, or of wet web for fibre board production, on paper-making machines of the Fourdrinier type paper or board consisting on two or more layers
    • D—TEXTILES; PAPER
    • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
    • D21H—PULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
    • D21H11/00—Pulp or paper, comprising cellulose or lignocellulose fibres of natural origin only
    • D—TEXTILES; PAPER
    • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
    • D21H—PULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
    • D21H21/00—Non-fibrous material added to the pulp, characterised by its function, form or properties; Paper-impregnating or coating material, characterised by its function, form or properties
    • D21H21/06—Paper forming aids
    • D21H21/10—Retention agents or drainage improvers
    • D—TEXTILES; PAPER
    • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
    • D21H—PULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
    • D21H21/00—Non-fibrous material added to the pulp, characterised by its function, form or properties; Paper-impregnating or coating material, characterised by its function, form or properties
    • D21H21/14—Non-fibrous material added to the pulp, characterised by its function, form or properties; Paper-impregnating or coating material, characterised by its function, form or properties characterised by function or properties in or on the paper
    • D21H21/16—Sizing or water-repelling agents
    • D—TEXTILES; PAPER
    • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
    • D21H—PULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
    • D21H21/00—Non-fibrous material added to the pulp, characterised by its function, form or properties; Paper-impregnating or coating material, characterised by its function, form or properties
    • D21H21/14—Non-fibrous material added to the pulp, characterised by its function, form or properties; Paper-impregnating or coating material, characterised by its function, form or properties characterised by function or properties in or on the paper
    • D21H21/18—Reinforcing agents
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
    • G01B11/00—Measuring arrangements characterised by the use of optical techniques
    • G01B11/02—Measuring arrangements characterised by the use of optical techniques for measuring length, width or thickness
    • G01B11/06—Measuring arrangements characterised by the use of optical techniques for measuring length, width or thickness for measuring thickness ; e.g. of sheet material
    • G01B11/0616—Measuring arrangements characterised by the use of optical techniques for measuring length, width or thickness for measuring thickness ; e.g. of sheet material of coating
    • G01B11/0625—Measuring arrangements characterised by the use of optical techniques for measuring length, width or thickness for measuring thickness ; e.g. of sheet material of coating with measurement of absorption or reflection
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
    • G01B11/00—Measuring arrangements characterised by the use of optical techniques
    • G01B11/02—Measuring arrangements characterised by the use of optical techniques for measuring length, width or thickness
    • G01B11/06—Measuring arrangements characterised by the use of optical techniques for measuring length, width or thickness for measuring thickness ; e.g. of sheet material
    • G01B11/0691—Measuring arrangements characterised by the use of optical techniques for measuring length, width or thickness for measuring thickness ; e.g. of sheet material of objects while moving
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
    • G01B11/00—Measuring arrangements characterised by the use of optical techniques
    • G01B11/24—Measuring arrangements characterised by the use of optical techniques for measuring contours or curvatures

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Length Measuring Devices By Optical Means (AREA)

Abstract

The invention discloses a preparation process based on low-basis-weight high-strength coated white board paper, which comprises the following steps of: step 1: pulping; step 2: forming a base paper and monitoring; and step 3: judging whether the base paper meets the quality requirement; and 4, step 4: carrying out surface sizing and coating on the paper base passing through the step 3; and 5: carrying out surface monitoring through an online finished product surface property monitoring device; step 6: if the surface properties of the coated paper are found to be abnormal, an alarm is given, and the abnormal state is judged; according to the method, after paper base paper is formed, the surface shape of the paper base paper is monitored; abnormal conditions are discovered constantly; waste products caused by the quality problem of the base paper after coating is finished are avoided; the resource waste and the pollution to the environment can be greatly reduced; meanwhile, synchronously monitoring the coated finished paper; the waste product problem caused by the coating process is convenient to find; the overall quality of a production line is ensured; and automatic monitoring is realized.

Description

Preparation process based on low-basis-weight high-strength coated white board paper
Technical Field
The invention relates to the technical field of white board paper manufacturing, in particular to a preparation process based on low-basis-weight high-strength coated white board paper.
Background
At present, paper making enterprises take various measures to try low-carbon economy. At present, the common consensus in domestic industry is to reasonably utilize non-wood fiber resources and improve the recovery and utilization rate of waste paper. But another trend in positive significance is to increase the utilization rate of fiber resources, reduce the weight of paper unit area and allow the limited pulp raw material to produce more areas of paper or paperboard. On the premise of not influencing various physical properties, optical properties and running characteristics of the paper, the quantitative weight of the paper is reduced as much as possible, and the paper is a choice of a plurality of paper making enterprises.
The low quantitative and high strength means that the quantitative amount of paper used for packaging products is obviously reduced through innovation and improvement of production technology, the overall strength of the products is kept unchanged or improved, the production cost of the products is reduced to a certain degree, and the economic benefit of enterprises is improved. Innovations and improvements in paper packaging production include production design, production technology, production process, production equipment, and raw materials. The base paper weight is reduced, the production cost is also reduced, but the quality of the finished product still meets the basic requirement of the standard. This is the definition of low basis weight and high strength of paper packaging products and the inevitable trend of recycling economy. The low quantification of paper and paperboard leads to the reduction of thickness, and finally causes the problems of strength, opacity, stiffness reduction and strike-through of writing and printing paper; the stiffness and the ring crush strength of the paperboard can not meet the subsequent processing or use requirements and the like. Especially, the reduction of the paper ration also puts higher requirements on the original process technology of the production enterprises.
The prior Chinese patent is a low-quantitative high-strength coated white paperboard and a preparation process thereof, and the application number is CN 201410486116.0; discloses a manufacturing process of low-basis weight white board paper, which means that a controllable medium-high soft calender is adopted to control the glossiness and the roughness uniformity of the paper surface after the raw paper is coated and dried, wherein the soft calender temperature is 100-150 ℃, and the linear pressure is 15-35 KN/M; as is known, the overall thickness of the white paperboard is more likely to be uneven due to the reduced grammage of the white paperboard base paper; if the thickness of the white paperboard base paper is uneven, the subsequent gluing process is easy to cause uneven gluing, the glossiness and the roughness of the white paperboard base paper are affected, and even strike-through is caused; the rejection rate is improved, and the paper waste after gluing has larger environmental pollution and resource waste than the paper waste before gluing; therefore, when the low-quantitative white board is prepared, the paper abnormality needs to be found in time at the front end of the production line; and processing is carried out in time; the integral strength of the paper can be ensured;
however, most of the existing paper mills rely on the naked eyes of experienced production line operators to observe during the paper preparation process, or carry out spot check on products of the production line within a fixed time period, and the paper problems can not be found in time by the checking method; resulting in a large amount of paper waste.
In view of the above problems, it is necessary to research and develop a low-basis weight high-strength coated white board and a preparation process thereof, so that the production process of the low-basis weight high-strength white board is stable and the quality of the paper product is high.
Disclosure of Invention
The invention aims to provide a preparation process based on low-basis-weight high-strength coated white board paper, which is used for solving the problems in the background technology.
In order to achieve the purpose, the invention provides the following technical scheme:
the preparation process based on the low-basis-weight high-strength coated white board paper comprises the following steps of:
step 1: taking pulping raw materials including bleached hardwood pulp and bleached hardwood pulp according to the mass ratio of 50-70: blending pulp according to the proportion of 30-50, wherein the beating degree of the pulp after beating is as follows: bleaching hardwood pulp with an SR of 60-80 degrees and bleaching hardwood pulp with an SR of 20-40 degrees;
step 2: adding auxiliary materials including a retention aid and a reinforcing agent into the slurry; then pumping the mixed white water into an external white water tank of the paper machine through a variable-frequency speed-regulating slurry pump to be mixed and diluted with thick white water, pumping the mixed white water into a pressure screen through a fan pump to be screened, and then entering a slurry box to at least form a first paper base layer and a second paper base layer; forming a first paper base layer and a second paper base layer through two-fold net forming, squeezing and front-section drying to form base paper, and inputting the base paper into an online base paper surface property monitoring device for surface monitoring;
and step 3: obtaining surface character data of the base paper by an online base paper surface character monitoring device; judging whether the surface property data of the base paper is in a preset standard data range; if the standard data range is within the preset standard data range, conveying the base paper to a subsequent process; if the obtained surface property data of the base paper is not within the preset standard data range; giving an alarm and inputting the base paper into a recovery area for the pulping raw material in the step 1; meanwhile, obtaining and displaying abnormal areas of the abnormal paper; the worker can conveniently judge the reason of the abnormal formation;
and 4, step 4: surface sizing is carried out on the paper base passing through the step 3; the glue application amount is 1-2g/m2Then, carrying out back-stage drying; calendering is carried out after the rear section drying is finished; and entering a coating system to finish coating;
and 5: drying the paper coated in the step 4 by a hot air drying oven, and then carrying out surface monitoring by an online finished product surface property monitoring device;
step 6: if the surface properties of the coated paper are found to be abnormal, an alarm is given, and the abnormal state is judged; the staff is convenient to investigate the reason.
Preferably, the method for monitoring the surface of the base paper by the online base paper surface property monitoring device comprises the following steps:
s1: taking a base paper sample paper, and obtaining a plurality of groups of paper thickness data on the sample paper through a thickness measuring device, wherein each group of paper thickness data respectively forms a paper thickness curve; wherein, each group of paper thickness data comprises a plurality of thickness values which are vertical to the conveying direction of the paper and correspond to unit points on the paper;
s2: averaging the thickness data of each group of paper to obtain an average thickness curve of each unit point of the paper along the conveying direction vertical to the paper; as a standard contrast curve;
s3: during normal production, a plurality of groups of paper thickness data are obtained on the same batch of paper with the sample paper by a thickness measuring device; wherein, the thickness data of each group of paper comprises a plurality of thickness values which are vertical to the conveying direction of the paper and correspond to unit points on the paper; forming an actual thickness curve by each group of paper thickness data;
s4: calculating the average value of each group of actual thickness curves; obtaining an actual average thickness curve of each unit point on the paper along the conveying direction vertical to the paper in actual production;
s5: comparing the actual average thickness curve with the standard comparison curve, and when the value of the actual average thickness curve exceeds the threshold value of the standard comparison curve; while sending out the alarm; shooting surface property images of the paper to be detected through a high-definition camera device;
s6: converting the obtained surface character image into an actual gray value image; finding out a difference area in an actual gray value image; thereby obtaining the abnormal area on the surface of the paper.
Preferably, the method for finding out the differential area in the actual gray-value image includes the following steps:
d1, establishing a position coordinate system on the actual gray value image; taking the paper conveying direction as a Y axis; the direction perpendicular to the paper conveying direction is an X axis;
d2, the range position of the abnormal curve obtained by comparing the actual average thickness curve with the standard contrast curve is corresponding to the coordinate system;
d3, obtaining an abnormal image range area according to the abnormal curve range;
specifically; the actual average thickness curve takes the paper conveying direction as the Y axis; recording the thickness data of the paper by taking the X axis vertical to the paper conveying direction; when the abnormal curve range position is obtained; the area of the abnormal position on the Y axis can be judged according to the abnormal curve range; thereby reducing the range to be judged;
d4, acquiring the gray value of the reference point pixel in the range area of the abnormal image, and radiating outwards in a circle by taking the central point as the center of the circle; comparing the difference value between the gray value of the pixel of the adjacent point and the gray value of the central point to obtain a difference value T1; and recording the comparison quantity as S1; if T1 is less than or equal to 10; recording the gray value of the adjacent point; if T1 is more than 10, discarding the gray value of the adjacent point; and so on, when the value of S1 is greater than 50% of the image pixel points, the recorded gray values of all the adjacent points are averaged to obtain a standard gray value; if the quantity of S1 can not reach 50% of the image pixel points, re-searching the reference point, and obtaining a standard gray value based on the reference point;
d5, forming a standard gray image with the same size as the actual gray image by using the standard gray value;
d6, performing AND operation on the standard gray image and the first to-be-detected gray image to obtain pixel points which are different from the standard gray image in the first to-be-detected gray image, and framing the positions of the different pixel points to mark, so as to obtain the abnormal area on the surface of the paper.
Preferably, the thickness measuring device is arranged at the outlet of the base paper; the device comprises a first rotation thickness measuring unit, a second rotation thickness measuring unit, a third rotation thickness measuring unit and a fourth rotation thickness measuring unit; the first rotation thickness measuring unit, the second rotation thickness measuring unit, the third rotation thickness measuring unit and the fourth rotation thickness measuring unit are sequentially arranged along the paper conveying direction;
the measuring area of the first rotating thickness measuring unit is a first straight line to-be-measured area vertical to the paper conveying direction; the measuring area of the second rotary thickness measuring unit is a second straight line area to be measured which is vertical to the paper conveying direction; the measuring area of the third rotating thickness measuring unit is a third straight line area to be measured which is vertical to the paper conveying direction; the measuring area of the fourth rotating thickness measuring unit is a fourth straight line to-be-measured area vertical to the paper conveying direction; wherein; the first straight line waiting area, the second straight line waiting area, the third straight line waiting area and the fourth straight line waiting area are arranged at equal intervals from front to back along the paper conveying direction.
Preferably, the first straight line region to be measured, the second straight line region to be measured, the third straight line region to be measured and the fourth straight line region to be measured all include at least 3 groups of straight line units to be measured.
Preferably, the first rotation thickness measuring unit, the second rotation thickness measuring unit, the third rotation thickness measuring unit and the fourth rotation thickness measuring unit have the same structure; each comprises a measuring roller assembly and a supporting roller; the measuring roller assembly comprises a measuring roller body, and at least three groups of thickness measuring assemblies are arranged on the measuring roller body; the thickness measuring assembly comprises a fixing plate, two ends of the fixing plate are fixedly connected to two ends of the inner wall of the measuring roller body, a plurality of measuring thimbles are sequentially arranged on the fixing plate at equal intervals, and the measuring thimbles penetrate through the fixing plate and are connected with a reflecting plate at the top; the lower end part of the measuring thimble is connected with a connecting plate and also comprises an elastic piece, one end of the elastic piece is sleeved on the thimble and is abutted to the connecting plate, and the other end of the elastic piece is abutted to the bottom wall of the fixing plate; the measuring roller is characterized by further comprising a micro laser transmitter, the micro laser transmitter is fixed on the inner wall of the measuring roller body and is arranged on the same axis with the ejector pin, and a gyroscope sensor is arranged on the fixing plate.
Preferably, the measuring roller body comprises three groups of thickness measuring assemblies; and the three groups of thickness measuring assemblies are arranged at equal intervals.
Preferably, in the initial state, the distance from the end part of the thimble to the tangent of the measuring roller body is the same as the distance from the surface of the non-sized paper to the tangent of the measuring roller body. The thickness of the paper can thereby be detected.
Preferably, the thickness measuring assembly measures the thickness, and comprises the following steps:
a1: the micro laser transmitter transmits laser to the reflecting plate; obtaining an initial distance;
a2: the measuring roller body rotates, and when the gyroscope sensor detects that the measuring roller body is in a horizontal state; the micro laser transmitter transmits laser again to the reflecting plate; obtaining a measurement distance;
a3: by subtracting the measured distance from the initial distance, a sheet thickness value is obtained.
Preferably; the method for monitoring the surface property of the coated paper by the online finished product surface property monitoring device is the same as the method for monitoring the surface of the base paper by the online base paper surface property monitoring device.
Compared with the prior art, the invention has the beneficial effects that:
the invention provides a preparation process based on low-basis-weight high-strength coated white board paper, which is characterized in that after paper base paper is formed, the surface shape of the paper base paper is monitored; abnormal conditions are discovered constantly; waste products caused by the quality problem of the base paper after coating is finished are avoided; the resource waste and the pollution to the environment can be greatly reduced; meanwhile, synchronously monitoring the coated finished paper; the waste product problem caused by the coating process is convenient to find; the overall quality of a production line is ensured; and automatic monitoring is realized.
Drawings
FIG. 1 is a schematic view of an installation structure of a thickness measuring device according to the present invention;
FIG. 2 is a schematic structural diagram of an actual thickness profile of the present invention;
FIG. 3 is a schematic view of the structure of the measurement region of the present invention;
FIG. 4 is a schematic structural diagram of a thickness measuring device according to the present invention;
fig. 5 is an enlarged schematic view of a in fig. 4.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
Example 1
Referring to fig. 1-5, the present invention provides a technical solution:
step 1: taking pulping raw materials including bleached hardwood pulp and bleached hardwood pulp according to the mass ratio of 50-70: blending pulp according to the proportion of 30-50, wherein the beating degree of the pulp after beating is as follows: bleaching hardwood pulp with an SR of 60-80 degrees and bleaching hardwood pulp with an SR of 20-40 degrees;
step 2: adding auxiliary materials including a retention aid and a reinforcing agent into the slurry; then pumping the mixed white water into an external white water tank of the paper machine through a variable-frequency speed-regulating slurry pump to be mixed and diluted with thick white water, pumping the mixed white water into a pressure screen through a fan pump to be screened, and then entering a slurry box to at least form a first paper base layer and a second paper base layer; forming a first paper base layer and a second paper base layer through two-fold net forming, squeezing and front-section drying to form base paper, and inputting the base paper into an online base paper surface property monitoring device for surface monitoring;
and step 3: obtaining surface character data of the base paper by an online base paper surface character monitoring device; judging whether the surface property data of the base paper is in a preset standard data range; if the standard data range is within the preset standard data range, conveying the base paper to a subsequent process; if the obtained surface property data of the base paper is not within the preset standard data range; giving an alarm and inputting the base paper into a recovery area for the pulping raw material in the step 1; meanwhile, obtaining and displaying abnormal areas of the abnormal paper; the worker can conveniently judge the reason of the abnormal formation;
and 4, step 4: surface sizing is carried out on the paper base passing through the step 3; the glue application amount is 1-2g/m2Then, carrying out back-stage drying; calendering is carried out after the rear section drying is finished; and entering a coating system to finish coating;
and 5: drying the paper coated in the step 4 by a hot air drying oven, and then carrying out surface monitoring by an online finished product surface property monitoring device;
step 6: if the surface properties of the coated paper are found to be abnormal, an alarm is given, and the abnormal state is judged; the staff is convenient to investigate the reason.
The method for monitoring the surface of the base paper by the online base paper surface property monitoring device comprises the following steps:
s1: taking a base paper sample paper, and obtaining a plurality of groups of paper thickness data on the sample paper through a thickness measuring device, wherein each group of paper thickness data respectively forms a paper thickness curve; wherein, each group of paper thickness data comprises a plurality of thickness values which are vertical to the conveying direction of the paper and correspond to unit points on the paper;
s2: averaging the thickness data of each group of paper to obtain an average thickness curve of each unit point of the paper along the conveying direction vertical to the paper; as a standard contrast curve;
s3: during normal production, a plurality of groups of paper thickness data are obtained on the same batch of paper with the sample paper by a thickness measuring device; wherein, the thickness data of each group of paper comprises a plurality of thickness values which are vertical to the conveying direction of the paper and correspond to unit points on the paper; forming an actual thickness curve by each group of paper thickness data;
s4: calculating the average value of each group of actual thickness curves; obtaining an actual average thickness curve of each unit point on the paper along the conveying direction vertical to the paper in actual production;
s5: comparing the actual average thickness curve with the standard comparison curve, and when the value of the actual average thickness curve exceeds the threshold value of the standard comparison curve; while sending out the alarm; shooting surface property images of the paper to be detected through a high-definition camera device;
s6: converting the obtained surface character image into an actual gray value image; finding out a difference area in an actual gray value image; thereby obtaining the abnormal area on the surface of the paper.
The method for finding out the difference region in the actual gray value image comprises the following steps:
d1, establishing a position coordinate system on the actual gray value image; taking the paper conveying direction as a Y axis; the direction perpendicular to the paper conveying direction is an X axis;
d2, the range position of the abnormal curve obtained by comparing the actual average thickness curve with the standard contrast curve is corresponding to the coordinate system;
d3, obtaining an abnormal image range area according to the abnormal curve range;
specifically; the actual average thickness curve takes the paper conveying direction as the Y axis; recording the thickness data of the paper by taking the X axis vertical to the paper conveying direction; when the abnormal curve range position is obtained; the area of the abnormal position on the Y axis can be judged according to the abnormal curve range; thereby reducing the range to be judged;
d4, acquiring the gray value of the reference point pixel in the range area of the abnormal image, and radiating outwards in a circle by taking the central point as the center of the circle; comparing the difference value between the gray value of the pixel of the adjacent point and the gray value of the central point to obtain a difference value T1; and recording the comparison quantity as S1; if T1 is less than or equal to 10; recording the gray value of the adjacent point; if T1 is more than 10, discarding the gray value of the adjacent point; and so on, when the value of S1 is greater than 50% of the image pixel points, the recorded gray values of all the adjacent points are averaged to obtain a standard gray value; if the quantity of S1 can not reach 50% of the image pixel points, re-searching the reference point, and obtaining a standard gray value based on the reference point;
d5, forming a standard gray image with the same size as the actual gray image by using the standard gray value;
d6, performing AND operation on the standard gray image and the first to-be-detected gray image to obtain pixel points which are different from the standard gray image in the first to-be-detected gray image, and framing the positions of the different pixel points to mark, so as to obtain the abnormal area on the surface of the paper.
Specifically, the method comprises the following steps: the thickness measuring device is arranged at the outlet of the base paper; comprises a first rotation thickness measuring unit 1, a second rotation thickness measuring unit 2, a third rotation thickness measuring unit 3 and a fourth rotation thickness measuring unit 4; the first rotation thickness measuring unit, the second rotation thickness measuring unit, the third rotation thickness measuring unit and the fourth rotation thickness measuring unit are sequentially arranged along the paper conveying direction;
the measuring area of the first rotary thickness measuring unit is a first straight line to-be-measured area 5 vertical to the paper conveying direction; the measuring area of the second rotating thickness measuring unit is a second straight line area to be measured 6 which is vertical to the paper conveying direction; the measuring area of the third rotating thickness measuring unit is a third straight line area to be measured 7 which is vertical to the paper conveying direction; the measuring area of the fourth rotating thickness measuring unit is a fourth straight line to-be-measured area 8 vertical to the paper conveying direction; wherein; the first straight line waiting area, the second straight line waiting area, the third straight line waiting area and the fourth straight line waiting area are arranged at equal intervals from front to back along the paper conveying direction. The first straight line region to be measured, the second straight line region to be measured, the third straight line region to be measured and the fourth straight line region to be measured all comprise at least 3 groups of straight line units to be measured, and the first rotation thickness measuring unit, the second rotation thickness measuring unit, the third rotation thickness measuring unit and the fourth rotation thickness measuring unit are consistent in structure; each comprises a measuring roller assembly 9 and a support roller 10; the measuring roller assembly comprises a measuring roller body 11, and at least three groups of thickness measuring assemblies are arranged on the measuring roller body; the thickness measuring assembly comprises a fixing plate 12, two ends of the fixing plate are fixedly connected to two ends of the inner wall of the measuring roller body, a plurality of measuring thimbles 13 are sequentially arranged on the fixing plate at equal intervals, and the measuring thimbles penetrate through the fixing plate and are connected with a reflecting plate 14 at the top; the lower end part of the measuring thimble is connected with a connecting plate 15 and further comprises an elastic piece 16, one end of the elastic piece is sleeved on the thimble and abuts against the connecting plate, and the other end of the elastic piece abuts against the bottom wall of the fixing plate; the measuring roller is characterized by further comprising a miniature laser transmitter 17, wherein the miniature laser transmitter is fixed on the inner wall of the measuring roller body and is on the same axis with the ejector pin, a gyroscope sensor is arranged on the fixing plate, and the measuring roller body comprises three groups of thickness measuring assemblies; and the thickness measuring assemblies are arranged at equal intervals, and in an initial state, the distance from the end part of the thimble to the tangent of the measuring roller body is the same as the distance from the surface of the paper without glue application to the tangent of the measuring roller body. The thickness of the paper can be detected, and the thickness measuring component measures the thickness, and the method comprises the following steps:
a1: the micro laser transmitter transmits laser to the reflecting plate; obtaining an initial distance;
a2: the measuring roller body rotates, and when the gyroscope sensor detects that the measuring roller body is in a horizontal state; the micro laser transmitter transmits laser again to the reflecting plate; obtaining a measurement distance;
a3: by subtracting the measured distance from the initial distance, a sheet thickness value is obtained.
The method for monitoring the surface property of the coated paper by the online finished product surface property monitoring device is the same as the method for monitoring the surface of the base paper by the online base paper surface property monitoring device; the required thickness measuring device is arranged at the outlet of the coated paper; transmitting the measured data to a processing system through a thickness measuring device; displaying the abnormal result on a display screen; the worker can conveniently find out which procedure has problems according to the measuring structure; the reason of the problem is what, and whether the problem is an abnormality caused by the factor does not need to be repeatedly verified by experience like the existing manufacturing process; the production line quality and the exception handling efficiency can be greatly improved.
Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that changes, modifications, substitutions and alterations can be made in these embodiments without departing from the principles and spirit of the invention, the scope of which is defined in the appended claims and their equivalents.

Claims (9)

1. The preparation process based on the low-basis-weight high-strength coated white board paper is characterized by comprising the following steps of: the method comprises the following steps:
step 1: taking pulping raw materials including bleached hardwood pulp and bleached hardwood pulp according to the mass ratio of 50-70: blending pulp according to the proportion of 30-50, wherein the beating degree of the pulp after beating is as follows: bleaching hardwood pulp with an SR of 60-80 degrees and bleaching hardwood pulp with an SR of 20-40 degrees;
step 2: adding auxiliary materials including a retention aid and a reinforcing agent into the slurry; then the mixed white water is sent into an external white water groove of the paper machine by a variable-frequency speed-regulating slurry pump to be mixed and diluted with thick white water, and the mixed white water is sent to a pressure screen by a fan pump to be screened and then enters a slurry inlet box to at least form a first paper base layer and a second paper base layer; forming a first paper base layer and a second paper base layer through two-fold net forming, squeezing and front section drying to form base paper, and inputting the base paper into an online base paper surface property monitoring device for surface monitoring;
and step 3: obtaining surface character data of the base paper by an online base paper surface character monitoring device; judging whether the surface property data of the base paper is in a preset standard data range; if the standard data range is within the preset standard data range, conveying the base paper to a subsequent process; if the obtained surface property data of the base paper is not in the preset standard data range; giving an alarm and inputting the base paper into a recovery area for the pulping raw material in the step 1; obtaining and displaying abnormal areas of the abnormal paper; the worker can conveniently judge the reason of the abnormal formation;
and 4, step 4: surface sizing is carried out on the paper base passing through the step 3; the glue application amount is 1-2g/m2Then, carrying out back-stage drying; calendering is carried out after the rear section drying is finished; and entering a coating system to finish coating;
and 5: drying the paper coated in the step 4 by a hot air drying oven, and then carrying out surface monitoring by an online finished product surface property monitoring device;
step 6: if the surface properties of the coated paper are found to be abnormal, an alarm is given, and the abnormal state is judged; the staff is convenient to investigate the reason.
2. The process for preparing low basis weight, high strength coated white board according to claim 1, wherein: the method for monitoring the surface of the base paper by the online base paper surface property monitoring device comprises the following steps:
s1: taking a base paper sample paper, and obtaining a plurality of groups of paper thickness data on the sample paper through a thickness measuring device, wherein each group of paper thickness data respectively forms a paper thickness curve; each group of paper thickness data comprises a plurality of thickness values which are vertical to the conveying direction of the paper and correspond to unit points on the paper;
s2: averaging the thickness data of each group of paper to obtain an average thickness curve of each unit point of the paper along the direction perpendicular to the conveying direction of the paper; as a standard contrast curve;
s3: during normal production, a plurality of groups of paper thickness data are obtained on the same batch of paper with the sample paper through a thickness measuring device; wherein, the thickness data of each group of paper comprises a plurality of thickness values which are vertical to the conveying direction of the paper and correspond to unit points on the paper; forming an actual thickness curve by each group of paper thickness data;
s4: calculating the average value of each group of actual thickness curves; obtaining an actual average thickness curve of each unit point on the paper along the conveying direction vertical to the paper in actual production;
s5: comparing the actual average thickness curve with the standard comparison curve, and when the value of the actual average thickness curve exceeds the threshold value of the standard comparison curve; while sending out the alarm; shooting a surface property image of the paper to be detected through a high-definition camera device;
s6: converting the obtained surface character image into an actual gray value image; finding out a difference area in an actual gray value image; thereby obtaining the abnormal area on the surface of the paper.
3. The process for preparing low basis weight, high strength coated white board according to claim 2, wherein: the method for finding out the difference region in the actual gray value image comprises the following steps:
d1, establishing a position coordinate system on the actual gray value image; taking the paper conveying direction as a Y axis; the direction perpendicular to the paper conveying direction is an X axis;
d2, the range position of the abnormal curve obtained by comparing the actual average thickness curve with the standard contrast curve is corresponding to the coordinate system;
d3, obtaining an abnormal image range area according to the abnormal curve range;
specifically; the actual average thickness curve takes the paper conveying direction as the Y axis; recording the thickness data of the paper by taking the X axis vertical to the paper conveying direction; when the abnormal curve range position is obtained; the area of the abnormal position on the Y axis can be judged according to the range of the abnormal curve; thereby reducing the range to be judged;
d4, acquiring the gray value of the reference point pixel in the range area of the abnormal image, and radiating outwards in a circle by taking the central point as the center of the circle; comparing the difference value between the gray value of the pixel of the adjacent point and the gray value of the central point to obtain a difference value T1; and recording the comparison quantity as S1; if T1 is less than or equal to 10; recording the gray value of the adjacent point; if T1 is more than 10, discarding the gray value of the adjacent point; and so on, when the value of S1 is greater than 50% of the image pixel points, the recorded gray values of all the adjacent points are averaged to obtain a standard gray value; if the quantity of S1 can not reach 50% of the image pixel points, re-searching the reference points, and obtaining the standard gray value based on the reference points;
d5, forming a standard gray image with the same size as the actual gray image by using the standard gray value;
d6, performing AND operation on the standard gray image and the first to-be-detected gray image to obtain pixel points which are different from the standard gray image in the first to-be-detected gray image, and framing the positions of the different pixel points to make marks, so as to obtain the abnormal area on the surface of the paper.
4. The process for preparing low basis weight, high strength coated white board according to claim 2, wherein: the thickness measuring device is arranged at the outlet of the base paper; the device comprises a first rotation thickness measuring unit, a second rotation thickness measuring unit, a third rotation thickness measuring unit and a fourth rotation thickness measuring unit; the first rotation thickness measuring unit, the second rotation thickness measuring unit, the third rotation thickness measuring unit and the fourth rotation thickness measuring unit are sequentially arranged along the paper conveying direction;
the measuring area of the first rotating thickness measuring unit is a first straight line to-be-measured area vertical to the paper conveying direction; the measuring area of the second rotary thickness measuring unit is a second straight line area to be measured which is vertical to the paper conveying direction; the measuring area of the third rotary thickness measuring unit is a third straight line area to be measured which is vertical to the paper conveying direction; the measuring area of the fourth rotating thickness measuring unit is a fourth straight line to-be-measured area vertical to the paper conveying direction; wherein; the first straight line waiting area, the second straight line waiting area, the third straight line waiting area and the fourth straight line waiting area are arranged at equal intervals from front to back along the paper conveying direction.
5. The process for preparing low basis weight, high strength coated white board according to claim 4, wherein: the first straight line area to be measured, the second straight line area to be measured, the third straight line area to be measured and the fourth straight line area to be measured all include at least 3 groups of straight line units to be measured.
6. The process for preparing low basis weight, high strength coated white board according to claim 4, wherein: the first rotation thickness measuring unit, the second rotation thickness measuring unit, the third rotation thickness measuring unit and the fourth rotation thickness measuring unit are consistent in structure; each comprises a measuring roller assembly and a supporting roller; the measuring roller assembly comprises a measuring roller body, and at least three groups of thickness measuring assemblies are arranged on the measuring roller body; the thickness measuring assembly comprises a fixed plate, two ends of the fixed plate are fixedly connected to two ends of the inner wall of the measuring roller body, a plurality of measuring thimbles are sequentially arranged on the fixed plate at equal intervals, and the measuring thimbles penetrate through the fixed plate and are connected with a reflecting plate at the top; the lower end part of the measuring thimble is connected with a connecting plate and also comprises an elastic piece, one end of the elastic piece is sleeved on the thimble and is abutted to the connecting plate, and the other end of the elastic piece is abutted to the bottom wall of the fixing plate; the measuring roller is characterized by further comprising a miniature laser transmitter, the miniature laser transmitter is fixed on the inner wall of the measuring roller body and is arranged on the same axis with the ejector pin, and a gyroscope sensor is arranged on the fixing plate.
7. The process for preparing low basis weight, high strength coated white board according to claim 6, wherein: the measuring roller body comprises three groups of thickness measuring components; and the three groups of thickness measuring assemblies are arranged at equal intervals.
8. The process for preparing low basis weight, high strength coated white board according to claim 6, wherein: in the initial state, the distance from the end part of the thimble to the tangent of the measuring roller body is the same as the distance from the surface of the paper without glue to the tangent of the measuring roller body. The thickness of the paper can thereby be detected.
9. The process for preparing low basis weight, high strength coated white board according to claim 6, wherein: a method of measuring thickness with a thickness measurement assembly, comprising the steps of:
a1: the micro laser transmitter transmits laser to the reflecting plate; obtaining an initial distance;
a2: the measuring roller body rotates, and when the gyroscope sensor detects that the measuring roller body is in a horizontal state; the micro laser transmitter emits laser again to the reflecting plate; obtaining a measurement distance;
a3: by subtracting the measured distance from the initial distance, a sheet thickness value is obtained.
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