CN111235963B - Insulating paperboard with cavity and preparation method thereof - Google Patents
Insulating paperboard with cavity and preparation method thereof Download PDFInfo
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- CN111235963B CN111235963B CN202010046900.5A CN202010046900A CN111235963B CN 111235963 B CN111235963 B CN 111235963B CN 202010046900 A CN202010046900 A CN 202010046900A CN 111235963 B CN111235963 B CN 111235963B
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- 239000011087 paperboard Substances 0.000 title claims abstract description 102
- 238000002360 preparation method Methods 0.000 title abstract description 5
- 239000000123 paper Substances 0.000 claims abstract description 135
- 230000007547 defect Effects 0.000 claims abstract description 58
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 53
- 238000007731 hot pressing Methods 0.000 claims abstract description 28
- 230000002950 deficient Effects 0.000 claims abstract description 23
- 238000001291 vacuum drying Methods 0.000 claims abstract description 21
- 238000004537 pulping Methods 0.000 claims abstract description 16
- 238000004519 manufacturing process Methods 0.000 claims abstract description 12
- 239000007788 liquid Substances 0.000 claims abstract description 9
- 238000000227 grinding Methods 0.000 claims abstract description 7
- 238000000034 method Methods 0.000 claims description 33
- 238000002474 experimental method Methods 0.000 claims description 20
- 238000007670 refining Methods 0.000 claims description 12
- 238000009413 insulation Methods 0.000 claims description 11
- 238000001035 drying Methods 0.000 claims description 10
- 238000011049 filling Methods 0.000 claims description 9
- 238000010009 beating Methods 0.000 claims description 8
- 239000002131 composite material Substances 0.000 claims description 7
- 238000007666 vacuum forming Methods 0.000 claims description 5
- 238000009966 trimming Methods 0.000 claims description 4
- 208000005156 Dehydration Diseases 0.000 claims description 3
- 230000018044 dehydration Effects 0.000 claims description 3
- 238000006297 dehydration reaction Methods 0.000 claims description 3
- 238000013461 design Methods 0.000 claims description 3
- 238000012545 processing Methods 0.000 claims description 3
- 239000011180 sandwich-structured composite Substances 0.000 claims description 3
- 238000005086 pumping Methods 0.000 claims description 2
- 238000000859 sublimation Methods 0.000 claims description 2
- 230000008022 sublimation Effects 0.000 claims description 2
- 230000009286 beneficial effect Effects 0.000 abstract description 2
- 238000001914 filtration Methods 0.000 abstract description 2
- 239000002994 raw material Substances 0.000 abstract 1
- 238000003756 stirring Methods 0.000 abstract 1
- 239000010410 layer Substances 0.000 description 25
- 239000000853 adhesive Substances 0.000 description 7
- 230000001070 adhesive effect Effects 0.000 description 7
- 239000003292 glue Substances 0.000 description 7
- 239000004698 Polyethylene Substances 0.000 description 6
- -1 polyethylene Polymers 0.000 description 6
- 229920000573 polyethylene Polymers 0.000 description 6
- 239000011111 cardboard Substances 0.000 description 3
- 238000010030 laminating Methods 0.000 description 3
- 238000003754 machining Methods 0.000 description 3
- 238000003825 pressing Methods 0.000 description 3
- 238000005520 cutting process Methods 0.000 description 2
- 238000011161 development Methods 0.000 description 2
- 239000012535 impurity Substances 0.000 description 2
- 239000011229 interlayer Substances 0.000 description 2
- 238000011160 research Methods 0.000 description 2
- 230000005540 biological transmission Effects 0.000 description 1
- 239000004567 concrete Substances 0.000 description 1
- 238000000605 extraction Methods 0.000 description 1
- 239000000835 fiber Substances 0.000 description 1
- 230000002427 irreversible effect Effects 0.000 description 1
- 238000012423 maintenance Methods 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 238000012544 monitoring process Methods 0.000 description 1
- 230000010287 polarization Effects 0.000 description 1
- 229920001225 polyester resin Polymers 0.000 description 1
- 239000004645 polyester resin Substances 0.000 description 1
- 238000007493 shaping process Methods 0.000 description 1
- 238000012360 testing method Methods 0.000 description 1
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-
- D—TEXTILES; PAPER
- D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
- D21J—FIBREBOARD; MANUFACTURE OF ARTICLES FROM CELLULOSIC FIBROUS SUSPENSIONS OR FROM PAPIER-MACHE
- D21J5/00—Manufacture of hollow articles by transferring sheets, produced from fibres suspensions or papier-mâché by suction on wire-net moulds, to couch-moulds
-
- 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
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
- H01B3/00—Insulators or insulating bodies characterised by the insulating materials; Selection of materials for their insulating or dielectric properties
- H01B3/18—Insulators or insulating bodies characterised by the insulating materials; Selection of materials for their insulating or dielectric properties mainly consisting of organic substances
- H01B3/48—Insulators or insulating bodies characterised by the insulating materials; Selection of materials for their insulating or dielectric properties mainly consisting of organic substances fibrous materials
- H01B3/52—Insulators or insulating bodies characterised by the insulating materials; Selection of materials for their insulating or dielectric properties mainly consisting of organic substances fibrous materials wood; paper; press board
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- Engineering & Computer Science (AREA)
- Manufacturing & Machinery (AREA)
- Life Sciences & Earth Sciences (AREA)
- Wood Science & Technology (AREA)
- Physics & Mathematics (AREA)
- Spectroscopy & Molecular Physics (AREA)
- Paper (AREA)
- Laminated Bodies (AREA)
Abstract
The invention discloses an insulating paperboard with a cavity and a preparation method thereof, which mainly comprises the following three steps: firstly, pulping a raw material pulp board by a pulper pulping refiner, filtering to obtain pure liquid pulp, uniformly stirring the pulp, and sending the pulp into a wet paper former to obtain a wet paper blank; secondly, defects with corresponding sizes are manufactured on the wet paper according to the size of the needed cavity by using a machine tool grinding tool, ice blocks with the same sizes as the gaps are filled, the wet paper blank containing the defects filled with the ice blocks is obtained, intact wet paper without the defects is placed on the upper layer and the lower layer, defective wet paper containing the ice blocks is placed on the middle layer, water is pumped by vacuum pressurization, and the sandwich-structure wet paper blank containing the defective wet paper filled with the ice blocks is manufactured. And thirdly, conveying the sandwich-structure wet paper blank containing the defective wet paper into a hot press for hot pressing, and performing vacuum drying. The invention can be used for manufacturing the insulating paper boards with different sizes of cavity defects, and is beneficial to accurately obtaining the discharge characteristic of the insulating paper boards with the cavity defects in engineering application.
Description
Technical Field
The invention relates to the technical field of high voltage and insulation, in particular to an insulating paperboard with a cavity and a preparation method thereof.
Background
The converter transformer is in a core position in an ultrahigh voltage transmission system in China, and the stable operation of the converter transformer plays a vital role in the reliable operation of a power grid. Partial discharges caused by very small defects in the insulating paper sheets in transformer oil paper insulation composite structures can lead to irreversible damage to the insulation properties. The air gap is a common defect type, the development state of air gap discharge is observed and measured in a high-voltage test, the air gap discharge monitoring method is extremely important for making a reasonable transformer maintenance plan, and the air gap discharge research has important academic significance and value. Insulating cardboard with cavities is an essential part of the indispensable need as a defect model.
In different environments and working states of the transformer, the cavity defects generated by the insulating paper boards in the insulating structure are different. When the method is used for analyzing the insulating discharge characteristics of the oiled paper caused by the cavities in a high-voltage experiment, the insulating paper boards containing the cavities with different sizes and the cavities at different specific positions need to be prepared, a cavity defect model is applied to a three-layer insulating paper board with a hollow cylinder, the existing preparation method mainly comprises the steps of (1) using a polyethylene sheet strip structure sandwiched between the insulating paper boards at two sides, drawing out the polyethylene sheet strip after pressing the paper boards to form a through air gap, but causing local damage, and having great difficulty in preparing the insulating paper boards with the cavity defects of different sizes and inconsistent with the cavities generated by the insulating paper boards in the actual engineering; (2) the insulating paperboard is pasted by using other insulating adhesive glue such as polyester resin and the like, the defects also exist, for example, bubbles are easy to appear on the glue layer part, the thickness of the glue layer influences the experimental measurement, and other impurities are generated under the high-pressure condition to form interface polarization. The insulating paperboard containing glue or the interlayer arranged between the paperboards is molded and then is drawn out to cause local damage and air gap through, so that the insulating characteristic of the insulating paperboard containing cavity defects in practical engineering application cannot be accurately simulated.
Disclosure of Invention
The present invention is directed to an insulating paperboard with cavities and a method for manufacturing the same, which solves the problems set forth in the background art.
According to the invention, the defects of cutting in the paperboard manufacturing process are filled with ice blocks, and the insulating paperboard with the cavity prepared by the hot-pressing drying wet paper blank method can reach the condition that the components are completely the same as those of the insulating paperboard in the transformer oiled paper insulating structure, so that the local damage caused by the extraction of the polyethylene thin strips is well avoided, and the development state of cavity discharge is better monitored.
The purpose of the invention is realized by the following technical scheme: an insulating paperboard having cavities is prepared by filling paperboard defects with ice cubes.
Further: the insulation paper board comprises three parts of two unnotched wet paper and a defective wet paper, wherein the middle position of the defective wet paper is provided with a circular size defect, the two unnotched wet paper are an upper layer and a lower layer, and the defective wet paper is positioned in the middle of the unnotched wet paper.
A method of making an insulating paperboard having cavities, the method comprising the steps of:
(1) preparing a wet paper blank: pulping the pulp board by a pulper, and then feeding the pulp board to a refiner for refining, wherein the refining degree is to ensure that the beating degree of pulp reaches 30-40 DEG SR, so as to obtain liquid pulp;
(2) sending the pulp into a pulp pool by using a pulp pump, carrying out filter residue treatment by using a filter residue device, and sending the pure pulp into a wet paper forming device by using the pulp pump to prepare formed wet paper;
(3) pressure dehydration treatment: dehydrating the wet paper to 55-65% by vacuum pressurization, and taking out a wet paper blank;
(4) manufacturing insulating paper boards of the cavity:
a. processing the formed wet paper blank into a recess or a notch with corresponding size and thickness on the wet paper blank by using a machine tool grinding tool according to the size of a cavity required by an experiment;
b. according to the defect size required by the experiment, making ice blocks with the same size and size, and filling the ice blocks in the paper boards with the defects;
c. placing intact wet paper without defect on the upper and lower layers, placing defective wet paper containing ice blocks on the middle layer to form a sandwich structure wet paper blank containing defective wet paper filled with ice blocks, pressurizing together with a mold until the water content reaches 40%, and taking out the sandwich structure wet paper blank;
(5) hot pressing and vacuum forming: conveying the wet paper blank with the sandwich structure in the step 4 into a hot press for hot pressing and carrying out vacuum drying treatment;
taking out the hot-pressed paperboard, and trimming the edge to obtain the sandwich-structured composite insulating paperboard with the cavity, wherein the composite insulating paperboard can be put into a high-voltage experiment; the middle layer contains defect wet paper and is put into ice blocks with the same size, and the ice blocks are sublimated to form cavities.
Further: and (2) feeding the pulp board into a pulper for pulping, feeding the pulp board into a pulping machine for pulping, wherein the pulping degree is that the beating degree of pulp reaches 30-40 DEG SR to obtain liquid pulp, feeding the pulp into a pulp tank by using a pulp pump, carrying out filter residue treatment by using a filter residue device, feeding pure pulp into a wet paper forming device by using the pulp pump to prepare formed wet paper, pumping water under pressure, and taking out wet paper blanks when the water content reaches 55-65%.
Further: and (5) pressing for 10-20min under the condition of hot pressing at 15-20 MPa.
Further: and (5) performing vacuum drying on the water-containing paperboard in a vacuum drying oven with the vacuum degree of 0.01-0.06MPa at the temperature of 100-110 ℃, wherein the drying time is about 2-3 h.
Further: and (4) setting different cavity sizes and specific positions of the cavities according to actual use requirements, wherein the generated defects cannot be communicated and are the same as air gaps generated in the use process of the insulating paperboard in the actual engineering field.
Further: the defects of the wet paper blank design are filled with ice blocks, and the ice blocks can generate vapor sublimation in the hot-pressing drying process to form cavities.
Further: in the step (4), the sandwich wet paper blank structure forms an insulating paperboard with a cavity in the hot pressing process, and the components of the insulating paperboard are completely the same as those of insulating paperboards in the actual engineering field.
Further: the diameter of the cavity in the sandwich structure with the cavity is 10-45mm, and the height is 0.5-2 mm.
Compared with the prior art, the invention utilizes the physical phenomenon to prepare the insulating paperboard with the cavity and has the beneficial effects that:
(1) the invention utilizes the sandwich wet paper blank with the defect of filling ice cubes to prepare the cavity paperboard, overcomes the defect that the polyethylene sheet strip is used for preparing the cavity in the prior art, but the interlayer is partially penetrated after the polyethylene sheet strip is drawn out after the polyethylene sheet strip is formed, can freely cut the defect of required size, and obtains the paperboards with the cavities of different sizes in the processes of filling with the ice cubes, hot-pressing and vacuum drying.
(2) In the process of laminating the multilayer insulating paper boards, no insulating adhesive is used, a wet paper hot pressing mode is adopted for laminating, the defect that the insulating paper board with the cavity defect used in the insulating discharge characteristic of the oiled paper due to the cavity contains the adhesive and the insulating characteristic of the insulating paper board with the cavity defect applied in the practical engineering cannot be accurately simulated is overcome, the components of the prepared cavity paper board are completely the same as those of the paper board used in the practical engineering field, and the phenomenon that the adhesive does not generate other impurities to influence the research on the discharge characteristic under various working conditions such as high temperature is avoided.
(3) The vacuum drying treatment is not only for obtaining the paperboard cavity, but also for avoiding the interference to the experiment caused by the moisture content of the paperboard in the high-pressure experiment process.
Drawings
Fig. 1 is a flow chart for preparing an insulating paperboard containing cavities.
FIG. 2 is a schematic representation of a sandwich wet blank containing ice-filled cavity defects.
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 embodiments, and all other embodiments obtained by a person of ordinary skill in the art without creative efforts based on the embodiments of the present invention belong to the protection scope of the present invention.
As shown in fig. 1-2, an insulation paperboard having a cavity is prepared by filling a paperboard defect with ice cubes.
In this embodiment, the insulating paper board includes three parts, i.e., two unnotched wet papers 3 and a defective wet paper 2, the defective wet paper 2 is provided with a size defect 1 having a circular shape at a middle position, the two unnotched wet papers 3 are an upper layer and a lower layer, and the defective wet paper 2 is located in the middle of the unnotched wet paper 3.
A method of making an insulating paperboard having cavities, the method comprising the steps of:
(1) preparing a wet paper blank: pulping the pulp board by a pulper, and then feeding the pulp board to a refiner for refining, wherein the refining degree is to ensure that the beating degree of pulp reaches 30-40 DEG SR, so as to obtain liquid pulp;
(2) sending the pulp into a pulp pool by using a pulp pump, carrying out filter residue treatment by using a filter residue device, and sending the pure pulp into a wet paper forming device by using the pulp pump to prepare formed wet paper;
(3) pressure dehydration treatment: dehydrating the wet paper to 55-65% by vacuum pressurization, and taking out a wet paper blank;
(4) manufacturing insulating paper boards of the cavity:
a. processing the formed wet paper blank into a recess or a notch with corresponding size and thickness on the wet paper blank by using a machine tool grinding tool according to the size of a cavity required by an experiment;
b. according to the defect size required by the experiment, making ice blocks with the same size and size, and filling the ice blocks in the paper boards with the defects;
c. placing intact wet paper without defect on the upper and lower layers, placing defective wet paper containing ice blocks on the middle layer to form a sandwich structure wet paper blank containing defective wet paper filled with ice blocks, pressurizing together with a mold until the water content reaches 40%, and taking out the sandwich structure wet paper blank;
(5) hot pressing and vacuum forming: conveying the wet paper blank with the sandwich structure in the step 4 into a hot press for hot pressing and carrying out vacuum drying treatment;
taking out the hot-pressed paperboard, and trimming the edge to obtain the sandwich-structured composite insulating paperboard with the cavity, wherein the composite insulating paperboard can be put into a high-voltage experiment; the middle layer contains defect wet paper and is put into ice blocks with the same size, and the ice blocks are sublimated to form cavities.
The size and the position of the defect can be freely manufactured according to the experimental requirement, and a machine tool grinding tool is used, so that the phenomenon that excessive corners are generated by manual cutting is avoided, and ice blocks with corresponding sizes are filled.
No insulating adhesive glue is used in the laminating hot pressing process of the sandwich wet paper blank structure model.
The hot pressing pressure condition is 15-20MPa, the paperboard fiber damage can be caused by overlarge pressure, and the multilayer wet paperboard has poor adhesion degree due to too small pressure.
During the hot pressing and vacuum drying processes, the ice blocks absorb heat and sublimate into water vapor at the temperature of 100 ℃ according to the physical principle to form a cavity in the paperboard.
In the embodiment, the pulp board is sent into a pulper for pulping in the step (1), then sent into a refiner for refining, the refining degree is that the beating degree of the pulp reaches 30-40 DEG SR, liquid pulp is obtained, a pulp pump is used for sending the pulp into a pulp tank, a residue filter is used for filtering residue, the pure pulp is sent into a wet paper former by the pulp pump to be made into formed wet paper, water is pumped under pressure, and the wet paper blank is taken out when the water content reaches 55% -65%.
In this embodiment, the hot pressing in the step (5) is performed under a pressure of 15 to 20MPa for 10 to 20 min.
In this embodiment, the step (5) of vacuum drying the water-containing paperboard is to perform vacuum drying at a temperature of 100-110 ℃ in a vacuum drying oven with a vacuum degree of 0.01-0.06MPa, and the drying time is about 2-3 hours.
In the embodiment, the sizes of the cavities and the specific positions of the cavities in the step (4) are set according to actual use requirements, the generated defects cannot be penetrated, and the air gaps are the same as those of the insulating paperboard in the actual engineering field in the use process.
In this embodiment, the defects of the wet paper blank design are filled with ice that sublimates with water vapor generated during the hot press drying process to form cavities.
In this embodiment, the sandwich wet paper blank structure in step (4) forms an insulating paper board with a cavity during the hot pressing process, and the composition of the insulating paper board is identical to that of the insulating paper board in the actual engineering field.
In this embodiment, the diameter of the cavity in the sandwich structure with the cavity is 10-45mm, and the height is 0.5-2 mm.
Different cavity sizes and the concrete position of cavity place can be designed to the defect that produces can not link up, avoids setting up the intermediate layer between the cardboard and takes out after the shaping and cause local damage, and is the same with the air gap that insulating paperboard in the actual engineering field produced in the use.
The sandwich wet paper blank structure forms the insulating paper board with the cavity in the hot pressing process, does not need to use any insulating adhesive glue, has the same components as the insulating paper board in the actual engineering field, and avoids the influence of the insulating adhesive glue on the experiment in the high-temperature and high-pressure process.
The first embodiment is as follows:
as shown in fig. 1-2, the method for preparing the insulating paperboard with the cavity comprises the following steps:
(1) wet paper production
1) And (3) pulping the pulp board by a pulper, and then feeding the pulp board to a refiner for refining, wherein the refining degree is to ensure that the beating degree of pulp reaches 30 DEG SR, so as to obtain liquid pulp.
2) And (3) sending the pulp into a pulp pond by using a pulp pump, carrying out filter residue treatment by using a filter residue device, and sending the pure pulp into a wet paper forming device by using the pulp pump to prepare formed wet paper.
3) The wet paper was dewatered to 55% by vacuum pressure, and the wet paper base was taken out.
(2) Defect creation
1) And (3) machining a depression or a notch with corresponding size and thickness on the wet paper blank by using a machine tool grinding tool according to the size of the cavity required by the experiment, namely, machining the middle-layer wet paper shown as 2 in the figure 2 by using the formed wet paper blank, and determining the diameter and the height of the defect 1 in the figure 2 to be 20mm and 1mm by using the wet paper according to the experiment requirement.
2) According to the defect size required by the experiment, ice blocks with the same size and size, the diameter of 20mm and the height of 1mm are made, and the ice blocks are filled in the paperboard with the defects to form wet paper for filling the defects of the ice blocks, as shown by the mark 2 in figure 2.
3) A layer of intact unnotched wet paper is firstly placed at the lowest layer in a wet paper blank making mold as shown in 3 in figure 2, a defective wet paper containing ice blocks is shown as the middle layer in 2 in the figure, a layer of intact unnotched wet paper 3 is placed at the uppermost layer, after fixation, a sandwich structure wet paper blank containing the defective wet paper filled with the ice blocks as shown in figure 2 is formed, the sandwich structure wet paper blank is pressurized together with the mold, the water content is 40%, and the sandwich structure wet paper blank is taken out.
(3) Hot pressing and vacuum forming
1) And (3) conveying the wet paper blank with the sandwich structure in the figure 2 into a hot press for hot pressing, wherein the hot pressing condition is 15MPa for 15 min.
2) The process of vacuum drying the water-containing paperboard is to carry out vacuum drying at the temperature of 105 ℃ in a vacuum drying oven with the vacuum degree of 0.01MPa, and the drying time is about 3 hours.
3) And taking out the hot-pressed paperboard, and performing edge finishing to obtain the sandwich structure composite insulating paperboard with the cavity diameter of 20mm and the height of 1mm, wherein the sandwich structure composite insulating paperboard can be used in a high-voltage experiment.
The second embodiment is as follows:
as shown in fig. 1-2, the method for preparing the insulating paperboard with the cavity comprises the following steps:
(1) wet paper production
1) And (3) pulping the pulp board by a pulper, and then feeding the pulp board to a refiner for refining, wherein the refining degree is to ensure that the beating degree of pulp reaches 37 DEG SR, so as to obtain liquid pulp.
2) And (3) sending the pulp into a pulp pond by using a pulp pump, carrying out filter residue treatment by using a filter residue device, and sending the pure pulp into a wet paper forming device by using the pulp pump to prepare formed wet paper.
3) The wet paper is dewatered to 60% by vacuum pressurization, and a wet paper blank is taken out.
(2) Defect creation
1) And (3) machining a depression or a notch with corresponding size and thickness on the wet paper blank by using a machine tool grinding tool according to the size of the cavity required by the experiment, namely, the wet paper of the middle layer shown as the mark 2 in the figure 2, wherein the diameter of the defect 1 of the wet paper is 40mm and the height of the defect 1 of the wet paper is 0.5mm according to the requirement of the experiment.
2) Ice cubes of the same size were made according to the size of the defect, the ice cubes having a diameter of 40mm and a height of 0.5mm, and the ice cubes were filled in the cardboard having the defect to constitute a defective wet paper containing the ice cubes, as shown by reference numeral 2 in fig. 2.
3) In the wet paper blank making mold, firstly, a layer of intact unnotched wet paper 3 is arranged at the lowest layer, the defective wet paper 2 containing ice blocks is used as the middle layer, and after the intact unnotched wet paper 3 is arranged at the uppermost layer for fixation, a sandwich-structure wet paper blank containing the defective wet paper filled with the ice blocks is formed, as shown in figure 2, the sandwich-structure wet paper blank is pressurized together with the mold, the water content reaches 45 percent, and the sandwich-structure wet paper blank is taken out.
(3) Hot pressing and vacuum forming
1) And (3) conveying the wet paper blank with the sandwich structure in the figure 2 into a hot press for hot pressing, wherein the hot pressing condition is that the pressing is carried out for 20min under the pressure of 20 MPa.
2) The process of vacuum drying the water-containing paperboard is to carry out vacuum drying in a vacuum drying oven with the vacuum degree of 0.05MPa at the temperature of 110 ℃, and the drying time is about 3 hours.
3) And taking out the hot-pressed paperboard, and trimming the edge to obtain the sandwich structure composite insulating paperboard with the cavity diameter of 40mm and the height of 0.5mm, which can be put into a high-voltage experiment for use.
Finally, it is noted that the above-mentioned embodiments illustrate rather than limit the invention, and that, although the present invention has been described in detail by way of examples, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the scope of the invention as defined by the appended claims.
It will be evident to those skilled in the art that the invention is not limited to the details of the foregoing illustrative embodiments, and that the present invention may be embodied in other specific forms without departing from the spirit or essential attributes thereof. The present embodiments are therefore to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein. Any reference sign in a claim should not be construed as limiting the claim concerned.
Furthermore, it should be understood that although the present description refers to embodiments, not every embodiment may contain only a single embodiment, and such description is for clarity only, and those skilled in the art should integrate the description, and the embodiments may be combined as appropriate to form other embodiments understood by those skilled in the art.
Claims (9)
1. An insulating paperboard with cavities, characterized in that: the insulation paperboard is prepared by filling ice blocks into paperboards to form defects, the ice blocks are filled into the defects cut in the paperboard manufacturing process, the insulation paperboard with a cavity is prepared by a hot-press drying wet paper blank method, the components of the insulation paperboard are completely the same as those of the insulation paperboard in an oil paper insulation structure of a transformer, the insulation paperboard comprises three parts, namely two unnotched wet paper (3) and a defective wet paper (2), the middle position of the defective wet paper (2) is provided with a circular size defect (1), the two unnotched wet paper (3) are an upper layer and a lower layer, and the defective wet paper (2) is positioned in the middle of the unnotched wet paper (3).
2. The method of manufacturing an insulating paperboard with cavities according to claim 1, characterized in that the method comprises the following steps:
(1) preparing a wet paper blank: pulping the pulp board by a pulper, and then feeding the pulp board to a refiner for refining, wherein the refining degree is to ensure that the beating degree of pulp reaches 30-40 DEG SR, so as to obtain liquid pulp;
(2) sending the pulp into a pulp pool by using a pulp pump, carrying out filter residue treatment by using a filter residue device, and sending the pure pulp into a wet paper forming device by using the pulp pump to prepare formed wet paper;
(3) pressure dehydration treatment: dehydrating the wet paper to 55-65% by vacuum pressurization, and taking out a wet paper blank;
(4) manufacturing insulating paper boards of the cavity:
a. processing the formed wet paper blank into a recess or a notch with corresponding size and thickness on the wet paper blank by using a machine tool grinding tool according to the size of a cavity required by an experiment;
b. according to the defect size required by the experiment, making ice blocks with the same size and size, and filling the ice blocks in the paper boards with the defects;
c. placing intact wet paper without defect on the upper and lower layers, placing defective wet paper containing ice blocks on the middle layer to form a sandwich structure wet paper blank containing defective wet paper filled with ice blocks, pressurizing together with a mold until the water content reaches 40%, and taking out the sandwich structure wet paper blank;
(5) hot pressing and vacuum forming: sending the sandwich structure wet paper blank in the step (4) into a hot press for hot pressing and carrying out vacuum drying treatment;
taking out the hot-pressed paperboard, and trimming the edge to obtain the sandwich-structured composite insulating paperboard with the cavity, namely the composite insulating paperboard can be put into an experiment; the middle layer contains defect wet paper and is put into ice blocks with the same size, and the ice blocks are sublimated to form cavities.
3. The method for preparing an insulating paperboard with cavities according to claim 2, characterized in that: and (2) feeding the pulp board into a pulper for pulping, feeding the pulp board into a pulping machine for pulping, wherein the pulping degree is that the beating degree of pulp reaches 30-40 DEG SR to obtain liquid pulp, feeding the pulp into a pulp tank by using a pulp pump, carrying out filter residue treatment by using a filter residue device, feeding pure pulp into a wet paper forming device by using the pulp pump to prepare formed wet paper, pumping water under pressure, and taking out wet paper blanks when the water content reaches 55-65%.
4. The method for preparing an insulating paperboard with cavities according to claim 2, characterized in that: the hot pressing condition in the step (5) is that the pressure is 15-20MPa for 10-20 min.
5. The method for preparing an insulating paperboard with cavities according to claim 2, characterized in that: the process of vacuum drying the water-containing paperboard in the step (5) is to carry out vacuum drying in a vacuum drying oven with the vacuum degree of 0.01-0.06MPa at the temperature of 100-110 ℃, and the drying time is 2-3 h.
6. The method for preparing an insulating paperboard with cavities according to claim 2, characterized in that: and (4) setting different cavity sizes and specific positions of the cavities according to actual use requirements, wherein the generated defects cannot be communicated and are the same as air gaps generated in the use process of the insulating paperboard in the actual engineering field.
7. The method for preparing an insulating paperboard with cavities according to claim 2, characterized in that: the defects of the wet paper blank design are filled with ice blocks, and the ice blocks can generate vapor sublimation in the hot-pressing drying process to form cavities.
8. The method for preparing an insulating paperboard with cavities according to claim 2, characterized in that: in the step (4), the sandwich wet paper blank structure forms an insulating paperboard with a cavity in the hot pressing process, and the components of the insulating paperboard are completely the same as those of insulating paperboards in the actual engineering field.
9. The method for preparing an insulating paperboard with cavities according to claim 2, characterized in that: the diameter of the cavity in the sandwich structure with the cavity is 10-45mm, and the height is 0.5-2 mm.
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| CA1170095A (en) * | 1982-05-19 | 1984-07-03 | Nordx/Cdt, Inc. | Control of diameter of fiber insulation on conductors |
| CN102967652A (en) * | 2012-12-05 | 2013-03-13 | 哈尔滨理工大学 | Electric strength inspection device for oil paper compound insulation oil during flowing |
| CN103790073A (en) * | 2014-02-18 | 2014-05-14 | 南通中菱绝缘材料有限公司 | Production method of thickened insulating paper plate |
| CN106381745A (en) * | 2016-11-14 | 2017-02-08 | 哈尔滨理工大学 | Preparation method of nano modified insulating paperboard for converter transformer |
| CN109736122A (en) * | 2019-03-15 | 2019-05-10 | 河南工学院 | Transformer insulating part process equipment |
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| CA1170095A (en) * | 1982-05-19 | 1984-07-03 | Nordx/Cdt, Inc. | Control of diameter of fiber insulation on conductors |
| CN102967652A (en) * | 2012-12-05 | 2013-03-13 | 哈尔滨理工大学 | Electric strength inspection device for oil paper compound insulation oil during flowing |
| CN103790073A (en) * | 2014-02-18 | 2014-05-14 | 南通中菱绝缘材料有限公司 | Production method of thickened insulating paper plate |
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| CN109736122A (en) * | 2019-03-15 | 2019-05-10 | 河南工学院 | Transformer insulating part process equipment |
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Denomination of invention: Insulating paperboard with cavity and its preparation method Effective date of registration: 20221026 Granted publication date: 20211123 Pledgee: Heilongjiang Xinzheng financing guarantee Group Co.,Ltd. Pledgor: Harbin Transformer Co.,Ltd. Registration number: Y2022230000082 |
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