CN110884226A - Preparation method of multi-order density paper honeycomb core material - Google Patents
Preparation method of multi-order density paper honeycomb core material Download PDFInfo
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- CN110884226A CN110884226A CN201911249824.1A CN201911249824A CN110884226A CN 110884226 A CN110884226 A CN 110884226A CN 201911249824 A CN201911249824 A CN 201911249824A CN 110884226 A CN110884226 A CN 110884226A
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B31—MAKING ARTICLES OF PAPER, CARDBOARD OR MATERIAL WORKED IN A MANNER ANALOGOUS TO PAPER; WORKING PAPER, CARDBOARD OR MATERIAL WORKED IN A MANNER ANALOGOUS TO PAPER
- B31D—MAKING ARTICLES OF PAPER, CARDBOARD OR MATERIAL WORKED IN A MANNER ANALOGOUS TO PAPER, NOT PROVIDED FOR IN SUBCLASSES B31B OR B31C
- B31D3/00—Making articles of cellular structure, e.g. insulating board
- B31D3/02—Making articles of cellular structure, e.g. insulating board honeycombed structures, i.e. the cells having an essentially hexagonal section
- B31D3/0223—Making honeycomb cores, e.g. by piling a plurality of web sections or sheets
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Abstract
The invention provides a preparation method of a multi-order density paper honeycomb core material, which comprises a gum dipping procedure, a pre-curing procedure, a gum coating procedure, an assembling procedure and a curing procedure, wherein the pre-curing procedure is to shape and pre-cure the gum dipped honeycomb paper on a waveform tool according to the required cell size to obtain the waveform honeycomb paper; the gluing process is to regularly coat and print the core strip glue on the upper surface of the wave crest of the corrugated honeycomb paper; the assembling procedure is to assemble the wave-shaped honeycomb paper after being coated with glue in a staggered way on a tool, and the lower surface of the wave peak of one wave-shaped honeycomb paper is assembled with the upper surface of the wave peak of the next wave-shaped honeycomb paper after being coated with glue. The invention relates to a new multi-density honeycomb design and manufacturing scheme designed on the basis of the existing honeycomb preparation and honeycomb splicing technology, and can be widely used for preparing functional honeycomb core materials sensitive to splicing seams, such as sound absorption, noise reduction, wave absorption and the like.
Description
Technical Field
The invention belongs to the technical field of non-metal composite material preparation, and particularly relates to a preparation method of a multi-order density paper honeycomb core material with variable density and controllable density in the unfolding direction.
Background
The paper honeycomb has a series of excellent performances such as light weight, high strength and the like, and becomes a preferred core material of a composite material honeycomb sandwich structure of an airplane, and the paper honeycomb not only effectively reduces the weight of the airplane structure and improves the processing performance of related parts, but also improves the use stability and prolongs the service life. With the improvement of the demand of the aerospace field for the functional diversity of the honeycomb sandwich structure, the honeycomb with single density can not meet the performance demand of the product.
The prior domestic multi-density paper honeycomb manufacture is mainly divided into two types: one is that the action of the foaming adhesive is taken as the center, the honeycomb and the honeycomb are spliced and solidified into a new whole by the foaming adhesive or other adhesives at high temperature, the method only utilizes the volume expansion of the foaming adhesive during the solidification at high temperature to bond the honeycombs on two sides together, but the fluidity of the foaming agent at high temperature can cause defects to the final product, the depth of the splicing seam between the honeycomb and the honeycomb is not controllable, and meanwhile, the introduction of the foaming adhesive or other adhesives can also increase the weight of the whole product and conflict with the weight reduction target of aerospace; the other type is that the honeycomb is taken as the center, the honeycomb is cut into a specific shape in a specific mode, and the two honeycombs are embedded in a tenon-and-mortise mode by using foaming glue or other adhesives as assistance, but the method is complex in operation and has higher requirement on the machining precision of the honeycomb.
On the other hand, the existing multi-density honeycomb preparation method usually needs secondary high-temperature treatment, and for paper-based honeycomb, the performance of the honeycomb is lost after the high-temperature treatment, and the design and the manufacture are adversely affected. Moreover, the adhesive in the prior art is usually a thermosetting material, and the adhesive at the abutted seams destroys the integrity of the honeycomb, which leads to the loss of the sound absorption, wave absorption and other functional properties of the honeycomb.
Disclosure of Invention
(1) Technical problem to be solved
The invention aims to provide a preparation method of a non-spliced multi-density paper honeycomb core material aiming at the defects of the spliced honeycomb, the prepared paper honeycomb core material can meet the requirement of the aerospace field on higher honeycomb sandwich structure function to a certain extent, the operation is simple, the one-step forming is realized, and the adverse effects possibly brought by secondary processing, such as product scrap caused by too deep splicing seams, honeycomb performance loss caused by high-temperature secondary treatment, sound absorption at splicing positions, wave absorption and other functional performance losses, can be reduced.
(2) Technical scheme
The invention aims to provide a preparation method of a non-spliced multi-density paper honeycomb core material aiming at the defects of the spliced honeycomb, the prepared paper honeycomb core material can meet the requirement of the aerospace field on higher honeycomb sandwich structure function to a certain extent, the operation is simple, the one-step forming is realized, and the adverse effects possibly brought by secondary processing, such as product scrap caused by too deep splicing seams, honeycomb performance loss caused by high-temperature secondary treatment, sound absorption at splicing positions, wave absorption and other functional performance losses, can be reduced.
The invention adopts the following technical scheme:
a preparation method of a multi-order density paper honeycomb core material comprises a gum dipping procedure, a pre-curing procedure, a gum coating procedure, an assembling procedure and a curing procedure, and is characterized in that the pre-curing procedure is to shape and pre-cure the gum dipped honeycomb paper on a waveform tool according to the required cell size to obtain the waveform honeycomb paper;
the gluing process is to regularly coat and print the core strip glue on the upper surface of the wave crest of the corrugated honeycomb paper;
the assembling procedure is to assemble the wave-shaped honeycomb paper after being coated with glue in a staggered way on a tool, and the lower surface of the wave peak of one wave-shaped honeycomb paper is assembled with the upper surface of the wave peak of the next wave-shaped honeycomb paper after being coated with glue.
Further, in the impregnation procedure, the glue applying amount of the honeycomb paper in the honeycomb paper impregnation process is controlled by changing the impregnation time and the lifting speed of the honeycomb paper, so that the honeycomb paper with different expected densities is obtained.
Further, in the above impregnation, the impregnating resin is a phenol resin, and the impregnating solvent is absolute ethyl alcohol.
The honeycomb paper is one of aramid fiber paper, plant fiber paper, polyester fiber paper and carbon fiber paper.
Further, the pre-curing procedure in the pre-curing is as follows: curing at 70-80 ℃ for 0.4-0.6h, continuing to heat to 115-125 ℃ for 0.4-0.6h, and then heating to 175-180 ℃ for 0.2-0.4 h.
Further, the core strip glue is modified epoxy-phenolic aldehyde compound resin.
Further, before the gluing process, the core strip glue is diluted by ethyl acetate.
And further, selecting the corresponding number of honeycomb paper with different densities according to the required density, and assembling to obtain the multi-density pre-cured honeycomb or the single-density pre-cured honeycomb.
Further, after the multi-density pre-cured honeycomb or the single-density pre-cured honeycomb is cured, the corresponding multi-density paper honeycomb core material or single-density pre-cured honeycomb core material is obtained.
Further, the curing procedure is as follows: heating to 115-125 ℃ for curing treatment for 0.4-0.6h, and then heating to 175-180 ℃ for curing treatment for 0.9-1.1 h.
(3) Advantageous effects
Advantageous effects of the present invention include the following as compared with the prior art.
(1) The preparation method of the multi-order density paper honeycomb core material provided by the invention is characterized in that the multi-density honeycomb is prepared at one time by changing the preparation process in the preparation of the multi-density honeycomb for the first time, so that seamless splicing is really realized, and the preparation method is more convenient and simpler in process route compared with the splicing route;
(2) the improvement on the process route of the invention avoids the performance loss of the honeycomb and the performance defect of the abutted seam caused by secondary cementation high-temperature treatment;
(3) the multi-density honeycomb prepared by the method can effectively improve the overall appearance of the honeycomb after splicing, and can effectively avoid the overall performance reduction caused by adhesive bonding for functional honeycomb structures such as wave-absorbing structures and the like;
(4) the invention fully integrates related mature technologies, realizes low-cost design, manufacture and technology integration comprehensive utilization, is a novel multi-density honeycomb design and manufacture scheme designed on the basis of the existing honeycomb preparation and honeycomb splicing technology, and can be widely used for preparing the functional honeycomb core materials sensitive to splicing seams, such as sound absorption, noise reduction, wave absorption and the like.
Drawings
FIG. 1 is a schematic diagram of a wave form of a pre-cured and shaped honeycomb paper.
Detailed Description
Embodiments of the present invention will be described in detail below with reference to examples, but it will be understood by those skilled in the art that the following examples are only illustrative of the present invention and should not be construed as limiting the scope of the present invention. The examples, in which specific conditions are not specified, were conducted under conventional conditions or conditions recommended by the manufacturer. The reagents or instruments used are not indicated by the manufacturer, and are all conventional products available commercially.
Example 1
This example was used to prepare 1/3(48 kg/m) having a cell size of 1.83mm and an overall size of 2.5m 1.2m 0.9m3)-1/3(80kg/m3)-1/3(48kg/m3) The preparation method of the aramid paper honeycomb core material comprises a gum dipping procedure, a precuring procedure, a gluing procedure, an assembling procedure and a curing procedure,
the specific preparation process comprises the following steps:
(1) impregnation step
In the embodiment, aramid paper with the thickness of 2mil is selected as a honeycomb paper base material, phenolic resin is selected as impregnating resin, absolute ethyl alcohol is selected as a dipping solvent, the proportion of the aramid paper and the impregnating resin is adjusted, and a densimeter is used for measuring the density of the aramid paper in the range of 0.9-1.1 g/cm3；
Cutting the aramid fiber paper at fixed length of 1.6m, sequentially putting the cut aramid fiber paper into a gumming tank for gumming, and adjusting gumming time, gumming times and lifting speed to 48kg/m3The weight of each piece of aramid paper after gum dipping of part of aramid paper is controlled to be 0.13-0.16kg and 80kg/m3Controlling the weight of each piece of aramid paper after gum dipping to be 0.21-0.28kg, and adjusting the required number of pieces of aramid paper according to the required density area, wherein the weight is 48kg/m3700 sheets of which the weight is 80kg/m3And 350 pieces.
(2) Precuring process
The method comprises the following steps of (1) carrying out shaping and pre-curing on the impregnated honeycomb paper on a waveform tool according to the required cell size to obtain the waveform honeycomb paper, wherein the waveform shape of the shaped honeycomb paper is shown in figure 1, and the pre-curing procedure is as follows: after curing at 70-80 ℃ for 0.4-0.6h, the temperature is continuously raised to 115-125 ℃ for 0.4-0.6h, and then raised to 175-180 ℃ for 0.2-0.4h, in this embodiment, the pre-curing procedure is as follows: after curing at 75 ℃ for 0.5h, continuously heating to 120 ℃ for curing for 0.5h, and then heating to 175 ℃ for curing for 0.3 h.
(3) Glue coating procedure
Preparing a core strip glue solution: taking modified epoxy-phenolic aldehyde compound resin as main resin, taking ethyl acetate as solvent, fully and uniformly stirring glue solution, and testing by using a standard 1-cup viscometer to control the viscosity range of the glue solution to be 25-35 s;
uniformly coating the prepared core strip glue on the upper surface of each wave crest of the shaped corrugated honeycomb paper;
(4) assembling procedure
The wave-shaped honeycomb paper after being coated with the glue is assembled on a tool in a staggered mode, the lower surface of the wave crest of one piece of wave-shaped honeycomb paper is assembled with the upper surface of the wave crest of the next piece of wave-shaped honeycomb paper after being coated with the glue, and the assembling sequence is 350 pieces of wave-shaped honeycomb paper with the weight of 48kg/m according to the requirement3Precured aramid paper and 350 pieces of 80kg/m3Pre-cured aramid paper, 350 pieces 48kg/m3Pre-curing aramid paper;
(5) curing step
And (3) post-curing the assembled pre-cured honeycomb to obtain the required aramid paper honeycomb core material, wherein the curing procedure is as follows: heating to 115-125 ℃ for curing treatment for 0.4-0.6h, and then heating to 175-180 ℃ for curing treatment for 0.9-1.1 h. The curing procedure in this example was: heating to 120 deg.C for curing for 0.5h, and heating to 175 deg.C for curing for 1.0 h.
The prepared aramid paper honeycomb core material is subjected to main mechanical property test at room temperature, wherein 48kg/m3The compression and shear strength of the density area reaches the performance index value of honeycomb with the specification of 1.83-48 in the enterprise standard Q/6S 1015-3The compression and shear strength of the density area reaches the performance index value of the honeycomb with the specification of 1.83-80 in the enterprise standard Q/6S 1948-.
TABLE 1 Multi-node Strength Performance test numerical Table
| Numbering | Multi-node strength/MPa |
| 1 | 0.0916 |
| 2 | 0.0897 |
| 3 | 0.0903 |
| 4 | 0.0932 |
| 5 | 0.0942 |
| Mean value of | 0.0918 |
The above description is only an example of the present application and is not limited to the present application. Various modifications and alterations to this application will become apparent to those skilled in the art without departing from the scope of this invention. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application should be included in the scope of the claims of the present application.
Claims (10)
1. A preparation method of a multi-order density paper honeycomb core material comprises a gum dipping procedure, a pre-curing procedure, a gum coating procedure, an assembling procedure and a curing procedure, and is characterized in that the pre-curing procedure is to shape and pre-cure the gum dipped honeycomb paper on a waveform tool according to the required cell size to obtain the waveform honeycomb paper;
the gluing process is to regularly coat and print the core strip glue on the upper surface of the wave crest of the corrugated honeycomb paper;
the assembling procedure is to assemble the wave-shaped honeycomb paper after being coated with glue in a staggered way on a tool, and the lower surface of the wave peak of one wave-shaped honeycomb paper is assembled with the upper surface of the wave peak of the next wave-shaped honeycomb paper after being coated with glue.
2. The method as claimed in claim 1, wherein in the step of dipping, the amount of applied glue to the honeycomb paper during the step of dipping the honeycomb paper is controlled by changing the dipping time and the lifting speed of the honeycomb paper, so as to obtain honeycomb papers with different expected densities.
3. The method as claimed in claim 2, wherein the impregnating resin is phenolic resin, and the impregnating solvent is absolute ethyl alcohol.
4. The method for preparing the honeycomb core material of multi-step density paper as claimed in claim 1 or 2, wherein the honeycomb paper is any one of aramid fiber paper, plant fiber paper, polyester fiber paper and carbon fiber paper.
5. The method for preparing a multi-step density paper honeycomb core material as claimed in claim 1, wherein the pre-curing procedure in the pre-curing is as follows: curing at 70-80 ℃ for 0.4-0.6h, continuing to heat to 115-125 ℃ for 0.4-0.6h, and then heating to 175-180 ℃ for 0.2-0.4 h.
6. The method for preparing the multi-step density paper honeycomb core material according to claim 1, wherein the core strip glue is modified epoxy-phenolic compound resin.
7. The method as claimed in claim 1, wherein the core strip glue is diluted with ethyl acetate before the glue coating step.
8. The method as claimed in claim 1, wherein the honeycomb core is prepared by assembling a plurality of honeycomb papers of different densities according to the required density to obtain a multi-density pre-cured honeycomb or a single-density pre-cured honeycomb.
9. The method for preparing the multi-order density paper honeycomb core material as claimed in claim 6, wherein the multi-density pre-cured honeycomb or the single-density pre-cured honeycomb is cured to obtain the corresponding multi-density paper honeycomb core material or the single-density pre-cured honeycomb core material.
10. The method for preparing a multi-step density paper honeycomb core material according to any one of claims 1, 2 or 9, wherein the curing procedure is as follows: heating to 115-125 ℃ for curing treatment for 0.4-0.6h, and then heating to 175-180 ℃ for curing treatment for 0.9-1.1 h.
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN111455723A (en) * | 2020-04-08 | 2020-07-28 | 长春珑鑫新材料有限公司 | Method for accurately controlling product density in production process of aramid paper honeycomb |
| CN112687357A (en) * | 2020-12-16 | 2021-04-20 | 中航复合材料有限责任公司 | Performance evaluation method of aramid paper for honeycomb |
Citations (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5399221A (en) * | 1990-05-04 | 1995-03-21 | Northrop Grumman Corporation | Continuous process for forming fiber-reinforced high temperature thermoplastic resin honeycomb structures |
| US6451406B1 (en) * | 2000-04-14 | 2002-09-17 | Hexcel Corporation | Solventless node adhesive for honeycomb |
| CN102501411A (en) * | 2011-09-29 | 2012-06-20 | 哈尔滨工业大学 | Methods for preparing composite material hexagonal honeycomb core with polymethacrylimide sandwich |
| CN103736624A (en) * | 2014-01-13 | 2014-04-23 | 苏州芳磊蜂窝复合材料有限公司 | Impregnation and gluing equipment for honeycomb and honeycomb preparation process with same |
| CN105946246A (en) * | 2016-05-10 | 2016-09-21 | 河北科技大学 | Preparation method for carbon fiber honeycomb core materials |
| CN106696360A (en) * | 2016-12-15 | 2017-05-24 | 中航复合材料有限责任公司 | Preparation method of para-aramid paper honeycomb core |
| CN106867251A (en) * | 2017-01-24 | 2017-06-20 | 杭州昂瑞阻燃科技有限公司 | A kind of prepreg and the method that honeycomb core is prepared by it |
| CN109572065A (en) * | 2018-12-19 | 2019-04-05 | 中航复合材料有限责任公司 | A kind of high-temperature resistant aramid fiber paper honeycomb core material and preparation method thereof |
-
2019
- 2019-12-09 CN CN201911249824.1A patent/CN110884226A/en active Pending
Patent Citations (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5399221A (en) * | 1990-05-04 | 1995-03-21 | Northrop Grumman Corporation | Continuous process for forming fiber-reinforced high temperature thermoplastic resin honeycomb structures |
| US6451406B1 (en) * | 2000-04-14 | 2002-09-17 | Hexcel Corporation | Solventless node adhesive for honeycomb |
| CN102501411A (en) * | 2011-09-29 | 2012-06-20 | 哈尔滨工业大学 | Methods for preparing composite material hexagonal honeycomb core with polymethacrylimide sandwich |
| CN103736624A (en) * | 2014-01-13 | 2014-04-23 | 苏州芳磊蜂窝复合材料有限公司 | Impregnation and gluing equipment for honeycomb and honeycomb preparation process with same |
| CN105946246A (en) * | 2016-05-10 | 2016-09-21 | 河北科技大学 | Preparation method for carbon fiber honeycomb core materials |
| CN106696360A (en) * | 2016-12-15 | 2017-05-24 | 中航复合材料有限责任公司 | Preparation method of para-aramid paper honeycomb core |
| CN106867251A (en) * | 2017-01-24 | 2017-06-20 | 杭州昂瑞阻燃科技有限公司 | A kind of prepreg and the method that honeycomb core is prepared by it |
| CN109572065A (en) * | 2018-12-19 | 2019-04-05 | 中航复合材料有限责任公司 | A kind of high-temperature resistant aramid fiber paper honeycomb core material and preparation method thereof |
Non-Patent Citations (3)
| Title |
|---|
| 李勇: "Nomex蜂窝在俄罗斯航空领域的发展及应用 ", 《材料工程》 * |
| 杨进军等: "大尺寸ACCH芳纶纸蜂窝浸胶工艺研究 ", 《航空制造技术》 * |
| 郑付来: "芳纶纸蜂窝酚醛树脂与国产芳纶纸的匹配性研究", 《高科技纤维与应用》 * |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN111455723A (en) * | 2020-04-08 | 2020-07-28 | 长春珑鑫新材料有限公司 | Method for accurately controlling product density in production process of aramid paper honeycomb |
| CN112687357A (en) * | 2020-12-16 | 2021-04-20 | 中航复合材料有限责任公司 | Performance evaluation method of aramid paper for honeycomb |
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Application publication date: 20200317 |