CN114566368A - Manufacturing process of insulation layer paper pressing plate capable of preventing cracking - Google Patents

Manufacturing process of insulation layer paper pressing plate capable of preventing cracking Download PDF

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Publication number
CN114566368A
CN114566368A CN202210144987.9A CN202210144987A CN114566368A CN 114566368 A CN114566368 A CN 114566368A CN 202210144987 A CN202210144987 A CN 202210144987A CN 114566368 A CN114566368 A CN 114566368A
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Prior art keywords
insulating
paper board
drying
cracking
board
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CN114566368B (en
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李洪
刘乾
陈志平
蒋志锋
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Changzhou Yingzhong Electrical Co ltd
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Changzhou Yingzhong Electrical Co ltd
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
    • H01F41/00—Apparatus or processes specially adapted for manufacturing or assembling magnets, inductances or transformers; Apparatus or processes specially adapted for manufacturing materials characterised by their magnetic properties
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
    • H01B19/00—Apparatus or processes specially adapted for manufacturing insulators or insulating bodies
    • H01B19/02—Drying; Impregnating
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
    • H01B19/00—Apparatus or processes specially adapted for manufacturing insulators or insulating bodies
    • H01B19/04—Treating the surfaces, e.g. applying coatings
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P70/00—Climate change mitigation technologies in the production process for final industrial or consumer products
    • Y02P70/10—Greenhouse gas [GHG] capture, material saving, heat recovery or other energy efficient measures, e.g. motor control, characterised by manufacturing processes, e.g. for rolling metal or metal working

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  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Manufacturing & Machinery (AREA)
  • Laminated Bodies (AREA)

Abstract

The invention provides a process for manufacturing an insulating laminated paperboard capable of preventing cracking, which comprises the working procedures of drying, independent cooling, non-aqueous binder gluing, secondary drying, side waxing and the like.

Description

Manufacturing process of insulation layer paper pressing plate capable of preventing cracking
Technical Field
The invention relates to the technical field of transformers, in particular to a manufacturing process of an insulating laminated paper board capable of preventing cracking.
Background
The insulating layer paper pressing plate is widely applied to the field of ultra-high voltage and plays a role in supporting and insulating the inside of the transformer. Insulating laminated paperboard is typically made by applying glue to individual sheets of insulating paperboard and then pressing the stacked sheets of paperboard with a press. Due to the complex process of the transformer, the insulating material is usually dried. Since the insulating laminated material must be exposed to the natural environment during the process and a certain moisture absorption occurs, the insulating laminated paper board can be used only by completely removing moisture through drying in order to improve the performance of the insulating material. The insulating paper board is made of paper fibers, and interlayer cracking is easily caused by shrinkage of the paper fibers in the drying process, so that the mechanical property of the product is seriously influenced. This situation has long plagued transformer and insulator manufacturers. How to avoid the problem that the insulating laminated material does not crack after being dried is also an urgent problem to be solved by various manufacturers. The current solution to the mainstream is to use screws 4 or rivets between the insulating laminated paperboard layers of the insulation to perform mechanical cracking prevention measures (as shown in fig. 3 and 4), but from the research on the insulation material, it is found that the mechanical addition of screws or rivets is likely to accelerate the cracking of the laminated material due to the inconsistent shrinkage of the material after drying, and the measures can only ensure that the laminated material does not continue to spread widely or expand the cracking degree after cracking. The occurrence of cracking of the insulating laminate after drying is not completely eliminated.
Disclosure of Invention
The technical problem to be solved by the invention is as follows: in order to overcome the defects in the prior art, the invention provides a manufacturing process of an insulating laminated paper board capable of preventing cracking.
For clarity of explanation of the technical solution, the following definitions of terms are given:
insulating single plate: the insulating single paperboard for manufacturing the insulating laminated paperboard is called an insulating single board for short.
The technical scheme adopted for solving the technical problems is as follows: a manufacturing process of an insulation laminated paper board capable of preventing cracking comprises the following steps:
step 1: drying
Before gluing, drying the insulated single board by adopting a single board vacuum drying process, and controlling the water content of the insulated single board to be below 0.5%;
step 2: cooling down
Placing the dried insulating single board in an independent and sealed cooling room for cooling, wherein the temperature in the cooling room is controlled to be 20-30 ℃, the humidity is controlled to be below 30%, and the temperature of the cooled insulating single board is less than 40 ℃;
and step 3: glue spreading
Gluing the cooled insulating single boards by an automatic gluing machine, gluing the two sides of each insulating single board, stacking the glued insulating single boards according to the required number, standing the stacked insulating paper boards for more than 24 hours after gluing, and entering a press for hot pressing after standing to form insulating layer pressed paper board blanks;
and 4, step 4: machining
Cutting the blank of the insulating layer pressed paper board after hot pressing by using machining equipment according to the drawing requirements of customers, then checking the appearance of the insulating layer pressed paper board after cutting, checking whether the appearance has sharp corners, burrs, pollution or cracking, and removing products with unqualified appearance;
and 5: secondary drying
Drying the insulating layer pressed paper board machined by adopting a drying mode of hot air circulation and slow temperature rise, wherein the drying process comprises the following steps: the initial setting temperature is 60 ℃, the temperature rises by 5 ℃ every 2 hours until the temperature rises to 80 ℃, and the temperature is maintained at 80 ℃ for 4 hours, so that the water content of the insulating laminated paper board is controlled below 2%;
step 6: side waxing
Coating No. 58 fully refined paraffin on the side surface of the insulating laminated paper board after secondary drying to finish the processing of the insulating laminated paper board.
In order to reduce the water absorption, step 3 is sized with a non-aqueous binder.
In order to control the water content, the whole machining process of step 4 needs to be completed within 24 hours.
Specifically, the machining device in step 4 includes one or more of a vertical lathe, a numerical control machine tool, a milling machine and a drilling machine.
The invention has the beneficial effects that: according to the manufacturing process of the anti-cracking insulating laminated paperboard, provided by the invention, the problem of cracking of the insulating laminated material is solved by controlling the water content of the insulating laminated material in the manufacturing process, and the cracking of the insulating laminated paperboard is effectively avoided.
Drawings
The invention is further illustrated by the following figures and examples.
FIG. 1 is a schematic flow chart of the manufacturing process of the present invention.
Fig. 2 is a structure of fiber arrangement inside the paperboard.
Fig. 3 is a schematic view of a conventional crack prevention measure of an insulator.
Fig. 4 is a side schematic view of the insulator of fig. 3.
In the figure: 1-upper surface, 2-lower surface, 3-end, 4-screw and 5-insulating laminated paper board.
Detailed Description
The present invention will now be described in detail with reference to the accompanying drawings. This figure is a simplified schematic diagram, and merely illustrates the basic structure of the present invention in a schematic manner, and therefore it shows only the constitution related to the present invention.
The nature of the insulation laminate cracking is due to the expansion and contraction of the paper fibers under different moisture content conditions, during which process significant internal stresses are generated within the laminate. Once this internal stress is greater than the ply bond of the paperboard or glue line, a cracking condition will necessarily occur. Therefore, the general cracking often occurs after vacuum drying, a large amount of water in the paper fiber is discharged in the vacuum drying process, and large internal stress is generated between material layers. The present invention solves the problem of cracking of an insulating laminate by a moisture control process for the insulating laminate during the manufacturing process.
First, the data shown in table 1 were obtained by testing:
TABLE 1 comparison table of water content and cracking risk
Water content of material Risk of cracking
＞6％ Height of
3～6％ In
＜3％ Is low in
The factory qualification standard of the insulating laminated paper board is defined according to IEC60763 as follows: the water content is less than or equal to 5 percent (non-aqueous glue) and the water content is less than or equal to 8 percent (aqueous glue). However, the moisture content of the actual insulating material is easily influenced by the natural environment through manufacturing, transportation, storage and use, and the moisture content is increased, and the situation is difficult to accurately monitor the insulating finished product by a monitoring means at present. Many times the moisture content of the insulation laminate prior to drying has been affected by the environment well above this standard. It is the core of the present invention how to ensure that the insulation laminate maintains a low moisture content before drying.
As shown in fig. 1, the manufacturing process of the paper pressing board for insulating layer for preventing cracking of the invention comprises the following steps:
step 1: drying the mixture
The insulating laminated paperboard is made of insulating single paperboard, and the insulating single paperboard is influenced by the storage environment. The moisture content of the insulating laminated paper board is inevitably too high without drying treatment before gluing. Therefore, before gluing, the insulating single plate is dried by adopting a single plate vacuum drying process, and the water content of the insulating single plate is controlled to be below 0.5%.
Step 2: cooling
The insulating veneer after the drying in step 1 can absorb moisture again if contacting with the natural environment in the cooling process, the internal water content is improved, and the early-stage drying effect is greatly reduced. Therefore, the dried insulating single plate is placed in an independent and sealed cooling room for cooling, the temperature in the cooling room is controlled to be 20-30 ℃, the humidity is controlled to be below 30 percent, and the temperature of the cooled insulating single plate is less than 40 ℃; the insulating single plates are cooled in an independent cooling room, so that the moisture content can be kept at a low level in the process.
And step 3: glue spreading
Gluing the cooled insulating single boards by an automatic gluing machine, gluing the two sides of each insulating single board, stacking the glued insulating single boards according to the required number, standing the stacked insulating paper boards for more than 24 hours after gluing, and entering a press for hot pressing after standing to form insulating layer pressed paper board blanks; in this embodiment, the non-aqueous binder is used for gluing, so that the increase of the overall water content caused by gluing can be greatly reduced. A further significant feature of non-aqueous binders is the ability to isolate moisture between layers. After the adhesive is applied, the upper surface and the lower surface of the insulating laminated paperboard material are not easy to absorb moisture due to the separation of the adhesive, and only the end part of the rear side surface is slightly absorbed moisture. The thickness of the insulating single board is generally thinner, for example, 3mm, if the thickness required by the customer is 30mm, 10 glued insulating single boards need to be stacked according to the thickness.
And 4, step 4: machining
The product can not be contacted with the natural environment in the processing process, so that the change rule of the material moisture under the environment with the humidity of 60 and the temperature of 25 ℃ is monitored. As shown in table 2:
TABLE 2 Exposure time and Water content Change comparison Table
Figure BDA0003507927510000051
Through the monitoring, the moisture content of the insulating material is found to increase at a moisture content increase rate of less than 1% every 24 hours of exposed storage. The risk of cracking is greatly reduced when compared to the previously tested insulation laminates having an overall moisture content of < 3%. The processing cycle time of the insulation product is set to not be > 24 hours. The measure can ensure that the integral water content of the insulating material is less than 3 percent.
Therefore, the step of machining specifically comprises: cutting the blank of the insulating layer pressed paper board after hot pressing by using machining equipment according to the drawing requirements of customers, then checking the appearance of the insulating layer pressed paper board after cutting, checking whether the appearance has sharp corners, burrs, pollution or cracking, and removing products with unqualified appearance; the whole machining process needs to be completed within 24 hours. Preferably, the machining equipment includes, but is not limited to, a vertical lathe, a numerical control machine, a milling machine, and a drilling machine.
And 5: secondary drying
The experiment in the step 4 shows that the water content of the product can be less than 3% theoretically after the processing process is finished within 24 hours, but the water content can still exceed 3% actually possibly influenced by a high-humidity environment (such as the plum rain season in the south of the Yangtze river). Therefore, a secondary drying process is adopted for the product, the product is dried again after being processed, the process aims to reduce the overall moisture content of the product and is different from the drying purpose of a transformer manufacturer (the drying purpose of the manufacturer is to completely remove the moisture in the insulating material so that the transformer oil is fully impregnated in the insulating material, and the paper insulating material has better insulating property after being fully impregnated with the oil, namely the dielectric constant is reduced, the electrical strength is improved.)
Therefore, the machined insulating layer pressed paper board is dried for the second time by adopting a drying mode of hot air circulation and slow temperature rise, and the drying process comprises the following steps: the initial set temperature is 60 ℃, the temperature rises by 5 ℃ every 2 hours until the temperature rises to 80 ℃, and the temperature is maintained for 4 hours, so that the water content of the insulating laminated paper board is controlled below 2 percent; the adoption of the slow heating mode not only reduces the water content, but also is not easy to cause the cracking of the material in the process.
Step 6: side waxing
The water content of the product after secondary drying can be controlled to be less than 2 percent, and the product has great difference with the water content of processing workshops, transportation, storage and use environments. The absence of a special moisture absorption prevention process will cause the water content of the material to rise again. As shown in fig. 2, the fiber arrangement structure inside the paperboard is that a layer of non-aqueous binder is wrapped on the fiber wall during gluing, so that the upper surface 1 and the lower surface 2 formed by the fiber wall are not easy to absorb moisture, the two side ends 3 of the fiber are exposed in the environment and are easy to absorb moisture, and the fiber wall expands to cause cracking after absorbing moisture, so that No. 58 fully refined paraffin is coated on the side end 3 of the insulating laminated board after secondary drying according to the side moisture absorption characteristic of the insulating material, and the processing of the insulating laminated board is completed. And finally, carrying out sealed packaging on the product. The use of wax No. 58 in this embodiment is common and permissible in the transformer industry, and other types may affect the performance of the product. The process can effectively prevent the secondary moisture absorption of the material. The paraffin can be completely separated from the insulating material by the gaseous kerosene when the client dries.
By the technical measures, the insulating laminated material can ensure that the integral water content is controlled to be less than 3% before the transformer manufacturer dries, and the problem that the laminated paperboard material cracks after drying is basically solved.
In light of the foregoing description of preferred embodiments in accordance with the invention, it is to be understood that numerous changes and modifications may be made by those skilled in the art without departing from the scope of the invention. The technical scope of the present invention is not limited to the contents of the specification, and must be determined according to the scope of the claims.

Claims (4)

1. The manufacturing process of the insulating laminated paper board capable of preventing cracking is characterized in that: the method comprises the following steps:
step 1: drying
Before gluing, drying the insulated single board by adopting a single board vacuum drying process, and controlling the water content of the insulated single board to be below 0.5%;
step 2: cooling down
Placing the dried insulating single board in an independent and sealed cooling room for cooling, wherein the temperature in the cooling room is controlled to be 20-30 ℃, the humidity is controlled to be below 30%, and the temperature of the cooled insulating single board is less than 40 ℃;
and step 3: glue spreading
Gluing the cooled insulating single boards by an automatic gluing machine, gluing the two sides of each insulating single board, stacking the glued insulating single boards according to the required number, standing the stacked insulating paper boards for more than 24 hours after gluing, and entering a press for hot pressing after standing to form insulating layer pressed paper board blanks;
and 4, step 4: machining
Cutting the blank of the insulating layer pressed paper board after hot pressing by using machining equipment according to the drawing requirements of customers, then checking the appearance of the insulating layer pressed paper board after cutting, checking whether the appearance has sharp corners, burrs, pollution or cracking, and removing products with unqualified appearance;
and 5: secondary drying
Drying the insulating layer pressed paper board machined by adopting a drying mode of hot air circulation and slow temperature rise, wherein the drying process comprises the following steps: the initial set temperature is 60 ℃, the temperature rises by 5 ℃ every 2 hours until the temperature rises to 80 ℃, and the temperature is maintained for 4 hours, so that the water content of the insulating laminated paper board is controlled below 2 percent;
and 6: side waxing
Coating No. 58 fully refined paraffin on the side surface of the insulating laminated paper board after secondary drying to finish the processing of the insulating laminated paper board.
2. The process for manufacturing a cracking-preventing insulating laminated paper board according to claim 1, wherein: and 3, gluing by using a non-aqueous binder.
3. The process for manufacturing a cracking-preventing insulating laminated paper board according to claim 1, wherein: step 4 the whole machining process needs to be completed within 24 hours.
4. The process for manufacturing a cracking-preventing insulating laminated paper board according to claim 1, wherein: and 4, machining equipment in the step 4 comprises one or more of a vertical lathe, a numerical control machine tool, a milling machine and a drilling machine.
CN202210144987.9A 2022-02-17 2022-02-17 Manufacturing process of insulating laminated paperboard capable of preventing cracking Active CN114566368B (en)

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Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2002217057A (en) * 2001-01-15 2002-08-02 Uht Corp Manufacturing device of ceramics laminate
CN102930948A (en) * 2012-11-15 2013-02-13 常州市英中电气有限公司 Insulating press ring for super-high voltage transformer and producing process thereof
US20150332835A1 (en) * 2012-12-19 2015-11-19 Abb Technology Ltd Transformer Insulation
CN110195374A (en) * 2019-05-10 2019-09-03 镇江市鑫泰绝缘材料有限公司 A kind of production method of insulating board
CN111648157A (en) * 2020-05-25 2020-09-11 潍坊汇胜绝缘技术有限公司 Production process of medium-density insulating paperboard

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2002217057A (en) * 2001-01-15 2002-08-02 Uht Corp Manufacturing device of ceramics laminate
CN102930948A (en) * 2012-11-15 2013-02-13 常州市英中电气有限公司 Insulating press ring for super-high voltage transformer and producing process thereof
US20150332835A1 (en) * 2012-12-19 2015-11-19 Abb Technology Ltd Transformer Insulation
CN110195374A (en) * 2019-05-10 2019-09-03 镇江市鑫泰绝缘材料有限公司 A kind of production method of insulating board
CN111648157A (en) * 2020-05-25 2020-09-11 潍坊汇胜绝缘技术有限公司 Production process of medium-density insulating paperboard

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