CN114566368B - Manufacturing process of insulating laminated paperboard capable of preventing cracking - Google Patents
Manufacturing process of insulating laminated paperboard capable of preventing cracking Download PDFInfo
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- CN114566368B CN114566368B CN202210144987.9A CN202210144987A CN114566368B CN 114566368 B CN114566368 B CN 114566368B CN 202210144987 A CN202210144987 A CN 202210144987A CN 114566368 B CN114566368 B CN 114566368B
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- insulating
- drying
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- laminated paperboard
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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
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- 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
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- 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
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- 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
Abstract
The invention provides a manufacturing process of an insulating laminated paperboard for preventing cracking, which comprises the procedures of drying, independent cooling, non-aqueous binder sizing, secondary drying, side waxing and the like.
Description
Technical Field
The invention relates to the technical field of transformers, in particular to a manufacturing process of an insulating laminated paperboard for preventing cracking.
Background
The insulating laminated paper board is widely applied to the field of ultra-high voltage and plays roles in supporting and insulating inside a transformer. The insulation laminate board manufacturing process is typically performed by applying glue to individual sheets of insulation board and then pressing the stacked board through a press. Because of the complex process of transformers, the insulation material generally needs to be dried. Because the insulation laminate must be exposed to the natural environment during processing, certain moisture absorption occurs, and in order to enhance the performance of the insulation laminate, the insulation laminate board can be used only by thoroughly removing moisture by drying. The insulating paperboard is essentially formed by paper fibers, and is easy to crack between layers due to shrinkage of the paper fibers in the drying process, so that the mechanical properties of the product are seriously affected. This situation has long plagued transformer and insulator manufacturers. How to avoid cracking of the insulation laminate after drying is also an urgent problem for various manufacturers. The current solution to the mainstream is to use a screw 4 or rivet means to mechanically prevent cracking between the insulating laminated cardboard layers of the insulation (as shown in fig. 3 and 4), but from studies on the insulation, it has been found that the mechanical increase of screws or rivets is likely to exacerbate cracking of the laminate due to inconsistent shrinkage of the material after drying, which only ensures that the laminate does not continue to propagate widely or propagate the degree of cracking after cracking. The occurrence of cracking of the insulation laminate after drying is not at all precluded.
Disclosure of Invention
The technical problems to be solved by the invention are as follows: in order to overcome the defects in the prior art, the invention provides a manufacturing process of an insulating laminated paperboard for preventing cracking.
For clarity of description of the technical solution, the following term definitions are given:
insulating veneer: refers to an insulating single paperboard, abbreviated as insulating veneer, used for manufacturing insulating laminated paperboard.
The technical scheme adopted for solving the technical problems is as follows: a process for manufacturing an insulation laminated paperboard which is resistant to cracking, comprising the steps of:
step 1: drying
Before gluing, drying the insulating single plate by adopting a single plate vacuum drying process, and controlling the water content of the insulating single plate to be below 0.5%;
step 2: cooling
Placing the dried insulating veneer 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 veneer is less than 40 ℃;
step 3: gluing
Gluing the cooled insulating single boards by an automatic gluing machine, carrying out double-sided gluing on each insulating single board, stacking the glued insulating single boards according to the required quantity, standing the stacked insulating paper boards for more than 24 hours after gluing, and entering a press for hot pressing after standing to form an insulating laminated paper board blank;
step 4: machining process
Performing size cutting on the insulating laminated paperboard blank after the hot pressing is finished by using machining equipment according to the requirements of a customer drawing, performing appearance inspection on the cut insulating laminated paperboard, checking whether sharp corners, burrs, pollution or cracking exist in the appearance, and removing products with unqualified appearance;
step 5: secondary drying
Drying the mechanically processed insulating laminated paperboard by adopting a drying mode of hot air circulation and slow temperature rise, and the drying process comprises the following steps: the temperature is initially set at 60 ℃, the temperature rises to 5 ℃ every 2 hours until the temperature rises to 80 ℃, and the temperature is maintained at 80 ℃ for 4 hours, so that the moisture content of the insulating laminated paperboard is controlled below 2%;
step 6: side waxing
And 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, a non-aqueous binder is used for sizing in step 3.
In order to control the water content, the whole machining process of the step 4 needs to be completed within 24 hours.
Specifically, the 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.
The beneficial effects of the invention are as follows: according to the manufacturing process of the insulating laminated paperboard for preventing cracking, 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 described below with reference to the drawings and examples.
FIG. 1 is a schematic flow chart of the manufacturing process of the present invention.
Fig. 2 is an arrangement of fibers within the paperboard.
Fig. 3 is a schematic view of a conventional anti-cracking measure of an insulating member.
Fig. 4 is a schematic side view of the insulator of fig. 3.
In the figure: 1-upper surface, 2-lower surface, 3-end, 4-screw, 5-insulation laminated paperboard.
Detailed Description
The present invention will now be described in detail with reference to the accompanying drawings. The figure is a simplified schematic diagram illustrating the basic structure of the invention only by way of illustration, and therefore it shows only the constitution related to the invention.
The cracking of the insulation laminate is essentially due to shrinkage expansion of the paper fibers at different moisture contents, during which process significant internal stresses are created within the laminate. Once this internal stress is greater than the interlayer adhesion of the cardboard or glue layers, cracking must occur. Therefore, the common cracking often occurs after the vacuum drying, and a large amount of water in the paper fiber is discharged in the vacuum drying process, so that larger internal stress can be generated between the material layers. The invention thoroughly solves the cracking problem of the insulating laminated material by controlling the water content of the insulating laminated material in the manufacturing process.
First, data as shown in table 1 were obtained by testing:
TABLE 1 Water content and crack risk score comparison Table
| Material water content | Risk of cracking |
| ＞6％ | |
| 3～6％ | In (a) |
| ＜3％ | Low and low |
The factory qualification standard for insulation laminated paperboard is defined according to IEC60763 as: 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 actual insulating material is easily affected by natural environment to increase the water content after being manufactured, transported, stored and used, and the situation is difficult to accurately monitor the insulating finished product by a monitoring means at present. Many times the moisture content of insulation laminates subjected to environmental influences prior to drying has far exceeded this standard. It is the core of the present invention how to ensure that the insulation laminate remains low in moisture content before drying.
As shown in fig. 1, a process for manufacturing an insulation laminated paperboard preventing cracking of the present invention includes the steps of:
step 1: drying
The insulating laminated board is composed of an insulating single board, and the insulating single board is influenced by the storage environment. The moisture content of the insulation laminated board must be too high without drying treatment before the glue application. Therefore, before gluing, the insulating single board is dried by adopting a single board vacuum drying process, and the water content of the insulating single board is controlled below 0.5%.
Step 2: cooling
The dried insulating veneer in the step 1 is contacted with natural environment in the cooling process, so that moisture can be absorbed again, the internal moisture content is improved, and the early 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%, and the temperature of the cooled insulating single plate is less than 40 ℃; cooling the insulating veneer in a separate cooling room ensures that the moisture content remains low during this process.
Step 3: gluing
Gluing the cooled insulating single boards by an automatic gluing machine, carrying out double-sided gluing on each insulating single board, stacking the glued insulating single boards according to the required quantity, standing the stacked insulating paper boards for more than 24 hours after gluing, and entering a press for hot pressing after standing to form an insulating laminated paper board blank; in the embodiment, the non-aqueous adhesive is adopted for the gluing, so that the increase of the overall water content caused by the gluing can be greatly reduced. A further significant feature of the non-aqueous binder is that it can sequester moisture between the layers. After the gluing, the upper surface and the lower surface of the insulating laminated paperboard material are not easy to absorb moisture due to isolation by the adhesive, and only the end part of the processed rear side surface can absorb a small amount of moisture. The thickness of the insulating veneer is generally relatively thin, such as 3mm, and if the thickness required by the customer is 30mm, 10 glued insulating veneers need to be stacked according to the thickness.
Step 4: machining process
The product is inevitably contacted with the natural environment in the processing process, so that the change rule of the moisture of the material in the environment with the humidity of 60 and the temperature of 25 ℃ is monitored. As shown in table 2:
TABLE 2 comparison of exposure time and moisture content
Through the above 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 bare storage. The risk of cracking is greatly reduced when the overall moisture content of the insulation laminate tested before is again compared to < 3%. The processing cycle of the insulation product must not be set to > 24 hours. The overall moisture content of the insulating material can be ensured to be less than 3% by the measure.
Thus, the step of machining specifically comprises: performing size cutting on the insulating laminated paperboard blank after the hot pressing is finished by using machining equipment according to the requirements of a customer drawing, performing appearance inspection on the cut insulating laminated paperboard, checking whether sharp corners, burrs, pollution or cracking exist in the appearance, and removing products with unqualified appearance; the entire 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.
Step 5: secondary drying
The experiment in the step 4 shows that although the water content of the product after the processing process is completed in 24 hours can be less than 3% in theory, the water content can still exceed 3% due to the influence of high humidity environment (such as plum rain season in Jiangnan). Therefore, the product is dried again after the finished product is processed by adopting a secondary drying process, the process aims to reduce the overall water content of the product and is different from the drying purpose of transformer factories (the drying purpose of the factories is to completely separate the water content in the insulating material so as to fully impregnate the insulating material with transformer oil, and the paper insulating material has better insulating property after being fully impregnated with oil, namely, the dielectric constant is reduced and the electric strength is improved.)
Therefore, the mechanical processing insulating laminated paper board is subjected to secondary drying by adopting a drying mode of hot air circulation and slow temperature rise, and the drying process comprises the following steps: the temperature is initially set at 60 ℃, the temperature rises to 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 paperboard is controlled below 2%; the slow heating mode reduces the water content and is not easy to cause 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%, 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 result in a re-increase in the moisture content of the material. As shown in fig. 2, since a layer of non-aqueous binder is coated on the fiber wall during gluing, the upper surface 1 and the lower surface 2 formed by the fiber wall are not easy to absorb moisture, and the two side ends 3 of the fiber are exposed in the environment and easy to absorb moisture, and the fiber wall expands to cause cracking after moisture absorption, so that the processing of the insulating laminated board is completed by coating 58 # full refined paraffin on the side end 3 of the insulating laminated board after secondary drying according to the side moisture absorption characteristics of the insulating material. And finally, sealing and packaging the product. The use of No. 58 wax in this embodiment is common and allowable in the transformer industry, and other models 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 customer dries.
By adopting the technical measures, the insulation laminated material can ensure that the overall water content is controlled to be less than 3 percent before the drying of transformer factories, and basically solves the problem of cracking of the laminated paperboard material after the drying.
While the foregoing is directed to the preferred embodiment of the present invention, other and further embodiments of the invention may be devised without departing from the basic scope thereof, and the scope thereof is determined by the claims that follow. The technical scope of the present invention is not limited to the description, but must be determined according to the scope of claims.
Claims (4)
1. A process for manufacturing an insulating laminated paperboard which is resistant to cracking, characterized by: the method comprises the following steps:
step 1: drying
Before gluing, drying the insulating single plate by adopting a single plate vacuum drying process, and controlling the water content of the insulating single plate to be below 0.5%;
step 2: cooling
Placing the dried insulating veneer 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 veneer is less than 40 ℃;
step 3: gluing
Gluing the cooled insulating single boards by an automatic gluing machine, carrying out double-sided gluing on each insulating single board, stacking the glued insulating single boards according to the required quantity, standing the stacked insulating paper boards for more than 24 hours after gluing, and entering a press for hot pressing after standing to form an insulating laminated paper board blank;
step 4: machining process
Performing size cutting on the insulating laminated paperboard blank after the hot pressing is finished by using machining equipment according to the requirements of a customer drawing, performing appearance inspection on the cut insulating laminated paperboard, checking whether sharp corners, burrs, pollution or cracking exist in the appearance, and removing products with unqualified appearance;
step 5: secondary drying
Drying the mechanically processed insulating laminated paperboard by adopting a drying mode of hot air circulation and slow temperature rise, and the drying process comprises the following steps: the temperature is initially set at 60 ℃, the temperature rises to 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 paperboard is controlled below 2%;
step 6: side waxing
And 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 producing a crack-resistant insulation laminated paperboard as claimed in claim 1, wherein: and 3, sizing by adopting a non-aqueous binder.
3. The process for producing a crack-resistant insulation laminated paperboard as claimed in claim 1, wherein: step 4 the entire machining process needs to be completed within 24 hours.
4. The process for producing a crack-resistant insulation laminated paperboard as claimed in claim 1, wherein: the 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.
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202210144987.9A CN114566368B (en) | 2022-02-17 | 2022-02-17 | Manufacturing process of insulating laminated paperboard capable of preventing cracking |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202210144987.9A CN114566368B (en) | 2022-02-17 | 2022-02-17 | Manufacturing process of insulating laminated paperboard capable of preventing cracking |
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| CN114566368A CN114566368A (en) | 2022-05-31 |
| CN114566368B true CN114566368B (en) | 2023-06-30 |
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Citations (4)
| 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 |
| 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 |
Family Cites Families (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| HUE043610T2 (en) * | 2012-12-19 | 2019-08-28 | Abb Schweiz Ag | Transformer insulation |
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- 2022-02-17 CN CN202210144987.9A patent/CN114566368B/en active Active
Patent Citations (4)
| 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 |
| 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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