CN115609948A - Preparation method of semi-cured flexible aramid fiber honeycomb core material - Google Patents
Preparation method of semi-cured flexible aramid fiber honeycomb core material Download PDFInfo
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- CN115609948A CN115609948A CN202211225128.9A CN202211225128A CN115609948A CN 115609948 A CN115609948 A CN 115609948A CN 202211225128 A CN202211225128 A CN 202211225128A CN 115609948 A CN115609948 A CN 115609948A
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
- B29C70/00—Shaping composites, i.e. plastics material comprising reinforcements, fillers or preformed parts, e.g. inserts
- B29C70/04—Shaping composites, i.e. plastics material comprising reinforcements, fillers or preformed parts, e.g. inserts comprising reinforcements only, e.g. self-reinforcing plastics
- B29C70/28—Shaping operations therefor
- B29C70/30—Shaping by lay-up, i.e. applying fibres, tape or broadsheet on a mould, former or core; Shaping by spray-up, i.e. spraying of fibres on a mould, former or core
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Abstract
The invention relates to the technical field of aramid honeycomb core materials, in particular to a preparation method of a semi-cured flexible aramid honeycomb core material. Compared with the prior art, the invention has the advantages that: the semi-cured flexible aramid honeycomb core material is manufactured by utilizing a phenolic resin gradient curing scheme, and the problems that a full-cured conventional honeycomb is easy to delaminate due to saddle effect, an irregular full-cured flexible honeycomb is high in manufacturing difficulty, low in efficiency and high in application cost, and semi-cured honeycomb conformal resin is easy to gather and generate bubbles are solved; the preparation process has the advantages of low difficulty, high preparation efficiency, easy realization of the application process, simple and easily controlled preparation process and high stability.
Description
Technical Field
The invention relates to the technical field of aramid fiber honeycomb core materials, in particular to a preparation method of a semi-solidified flexible aramid fiber honeycomb core material.
Background
The aramid fiber honeycomb core material has the characteristics of high strength, light weight, corrosion resistance, fatigue resistance, low dielectric property and the like, is widely applied to the application fields of high strength and low weight such as aerospace, rail transit and the like, and is suitable for the high-end fields of aerospace such as airborne, shipborne and spaceborne radars, antenna support structures and the like. The conventional manufacturing process flow of the aramid fiber honeycomb core material is as follows: gluing, superposing, hot pressing, trimming, stretching, shaping, dipping, curing, trimming, slicing, detecting and the like. The aramid fiber honeycomb made according to the process is in a full-curing state, the honeycomb is high in hardness, a saddle effect exists when a special-shaped multi-curved-surface structure is made, the resilience force is large, part delamination is easily generated, or after a forced die is formed, the honeycomb is extruded, and the strength and the rigidity are greatly reduced.
Part manufacturers develop irregular-cell full-curing flexible aramid honeycomb core materials with different free edges based on foreign examples, the manufacturing process of the full-curing product needs to shape aramid paper at high temperature and then glue, meanwhile, the aramid paper needs to be aligned in the middle at unequal intervals during overlapping, certain offset needs to be kept, the manufacturing difficulty is high, the error rate is high, the qualified rate is low, and the comprehensive cost is high. Meanwhile, resin surface aggregation and air bubbles are generated during the follow-up curing of the partially semi-cured honeycomb, and the bonding strength with the surface material is influenced.
Chinese patent No.: 202210344469.1 discloses a wave-absorbing honeycomb with an anti-surface cracking function and a preparation method thereof, wherein the wave-absorbing honeycomb comprises a semi-cured honeycomb body and a wave-absorbing honeycomb body, and the wave-absorbing honeycomb body comprises the following steps: and cutting the semi-cured honeycomb block into pieces to obtain honeycomb pieces with proper thickness, soaking the semi-cured honeycomb pieces in the wave-absorbing coating, drying, repeatedly operating for many times until the density of the honeycomb pieces meets the requirement, and co-curing the honeycomb pieces to obtain the wave-absorbing honeycomb pieces. The purpose of the semi-cured honeycomb of the patent is to increase bonding strength, prevent surface cracking, through accomplishing semi-curing earlier, impregnate wave-absorbing material again, do final solidification again, wave-absorbing material is better with base member surface bonding strength like this, can prevent surface cracking, but the material lacks flexibility, can produce saddle effect.
Disclosure of Invention
The invention aims to overcome the defects of the prior art and provides a flexible aramid fiber honeycomb core material which avoids saddle effect caused by paving and pasting special-shaped curved surfaces and has small product resilience.
In order to achieve the purpose, a preparation method of a semi-cured flexible aramid honeycomb core material is designed, and the method comprises the following steps:
s1, cutting aramid fiber honeycomb slices which are not impregnated with phenolic resin;
s2, soaking the aramid fiber honeycomb sheet in phenolic resin, then semi-curing at low temperature in an oven, measuring the density of the semi-cured honeycomb sheet, repeating the process for multiple times, and measuring the density of the semi-cured honeycomb sheet to enable the honeycomb to reach the target density and keep the flexibility;
and S3, selecting a set of die, paving and adhering the honeycomb section, and then carrying out high-temperature curing in an oven.
Preferably, the following components: the dipping process in the step S2 is that the honeycomb piece is soaked in a glue groove filled with phenolic resin for 5-6min to fully soak glue solution, then the cells are kept to vertically extract the glue solution, and the redundant glue solution is swept by an air knife after the aramid fiber honeycomb piece is discharged; the curing process is to keep the horizontal state of the cells, circulating air passes through the cells and is put into an oven, the heating rate is 3-5 ℃/min, the constant temperature heat preservation temperature is 120 +/-2 ℃ except for final semi-curing, the constant temperature heat preservation temperature is 100 +/-2 ℃ when final semi-curing is carried out, and the constant temperature heat preservation time is always 30 +/-3 min.
Preferably: the impregnation and semi-curing process in the step S2 comprises multiple times to realize uniform distribution of the phenolic resin, the final constant-temperature heat preservation temperature is 100 +/-2 ℃, the constant-temperature heat preservation temperatures of other times are 120 +/-2 ℃, the constant-temperature heat preservation time is 30min +/-3 min, and the temperature is reduced to the room temperature after 30-45 min after the single constant-temperature heat preservation.
Preferably: the aramid fiber honeycomb piece in the step S1 is prepared by high-speed piece cutting of shaped unimpregnated aramid fiber honeycomb blocks through a high-precision horizontal band sawing machine.
Preferably, the following components: the thickness of the aramid honeycomb piece in the step S1 is 3-50mm, the nominal cell side lengths are 1.83mm, 2.75mm, 4.80mm, 5.70mm and 7.20mm, and the nominal density is 18kg/m for conducting harvesting to 48kg/m for conducting harvesting.
Preferably: and S3, independently curing the core material along with the mold, wherein the paving mode is to pave a non-sticky release material on the surface of the mold, pave the semi-cured flexible aramid honeycomb core material, pave the non-sticky release material, pave a high-temperature vacuum film, tightly attach the honeycomb core material to the mold after vacuumizing, keep the target shape and ensure the vacuum degree to be-0.03 MPa to-0.05 MPa.
Preferably: the heating rate in the step S3 comprises two stages of 2-3 ℃/min and 5-7 ℃/min, and the constant temperature insulation temperature comprises two stages of 120 +/-2 ℃ and 175 +/-5 ℃; the curing process comprises the steps of heating to 120 +/-2 ℃ at room temperature according to the speed of 2-3 ℃/min in the first stage, keeping the temperature for 120 +/-5 min at constant temperature, continuously heating to 175 +/-3 ℃ from 120 ℃ at the speed of 5-7 ℃/min in the second stage, keeping the temperature for 45 +/-3 min at constant temperature, and cooling to room temperature 60-90 min after the constant temperature is kept.
Compared with the prior art, the invention has the advantages that: according to the invention, a phenolic resin gradient curing scheme is utilized to manufacture the semi-cured flexible aramid honeycomb core material and a corresponding application process, so that the problems that a full-cured conventional honeycomb is easy to delaminate due to saddle effect, an irregular full-cured flexible honeycomb is high in manufacturing difficulty, low in efficiency and high in application cost, and semi-cured honeycomb conformal resin is easy to gather and generate bubbles are solved; the method has the advantages of low difficulty of the manufacturing process, high preparation efficiency, easy realization of the application process, simple and easily controlled preparation process and high stability.
Detailed Description
Based on the technical scheme, the semi-solidified flexible aramid honeycomb core material with the side length of 2.75mm and the nominal density of 64 kg/m for heavy planting is prepared. Selecting non-impregnated aramid fiber honeycomb blocks with the side length of 2.75mm, the cells approximate to hexagons, the density of 22kg/m and the length and width of 1.25 x 2.50 x 0.85m, fixing the non-impregnated aramid fiber honeycomb blocks on a high-speed high-precision horizontal band sawing machine, setting the thickness, and slicing to obtain non-impregnated aramid fiber honeycomb slices with the thickness of 15 mm.
And (3) putting the unimpregnated aramid fiber honeycomb piece into a high-temperature-resistant phenolic resin glue tank, soaking for 5 minutes, keeping the cells to vertically extract glue, and blowing the honeycomb piece by using an air knife after the aramid fiber honeycomb piece is discharged from the glue, so as to remove redundant glue. And (3) putting the honeycomb structure into an oven in a horizontal state, heating to 120 ℃ according to the temperature of 4 ℃/min, preserving the heat at 120 ℃ for 30min, cooling to room temperature after 45min, taking out the honeycomb piece, measuring the density of 44 kg/m for carrying out thin film strip plantation, and finishing the first impregnation and semi-solidification.
And (3) placing the honeycomb sheet which is subjected to primary impregnation and semi-solidification into a high-temperature-resistant phenolic resin glue tank, soaking for 5 minutes, keeping the cells to vertically extract glue solution, and blowing the honeycomb sheet by using an air knife after the aramid fiber honeycomb sheet is discharged from the glue solution to remove redundant glue solution. And (3) keeping the cells in a horizontal state, putting the cells into an oven, heating to 100 ℃ according to the temperature of 4 ℃/min, keeping the temperature at 100 ℃ for 30min, cooling to room temperature for 30min, taking out the honeycomb piece, measuring the density of the honeycomb piece to be 65kg/m, and finishing the final secondary impregnation and semi-solidification to obtain the semi-solidified flexible aramid honeycomb core material with the side length of 2.75mm and the density of 65 kg/m. And partial honeycombs need more times of impregnation and semi-solidification circulation, and the final 100 ℃ heat preservation and the other 120 ℃ heat preservation are needed according to the preparation scheme of the invention.
The semi-solidified flexible aramid honeycomb core material prepared by the method and having the side length of 2.75mm and the density of 65kg/m is soft as a whole, consistent in state, capable of being bent in multiple curved surfaces, and simple and controllable in preparation process.
Selecting a set of semi-spherical mold, cleaning the surface of the mold, paving a layer of cut Teflon cloth to enable the Teflon cloth to be tightly attached to the mold, paving the semi-solidified flexible aramid honeycomb core material with the side length of 2.75mm and the density of 65kg/m for thin film production on the Teflon cloth, fixing the edge of the semi-solidified flexible aramid honeycomb core material with high-temperature-resistant glue, paving a layer of cut Teflon cloth on the upper surface of the honeycomb core material, paving a high-temperature vacuum film, and vacuumizing the whole to-0.04 MPa. Keeping the vacuum degree, putting the whole into an oven, heating to 120 ℃ at room temperature according to the speed of 2 ℃/min, keeping the temperature constant for 120min, then continuously heating from 120 ℃ to 175 ℃ according to the speed of 6 ℃/min, keeping the temperature constant for 45min, and cooling to room temperature 90min after the temperature constant is finished. And (3) taking out the cured honeycomb core material, wherein the surface of the honeycomb core material has no air bubbles, and the resin aggregation is basically absent, so that the bonding of the surface material is basically not influenced.
The above description is only for one embodiment of the present invention, but the scope of the present invention is not limited thereto, and any person skilled in the art should be considered as the technical solutions and novel concepts of the present invention within the technical scope of the present invention.
Claims (7)
1. A preparation method of a semi-solidified flexible aramid honeycomb core material is characterized by comprising the following steps of: the method comprises the following steps:
s1: cutting aramid fiber honeycomb slices which are not impregnated with phenolic resin;
s2: impregnating the aramid fiber honeycomb sheet with phenolic resin, performing low-temperature semi-curing in an oven, measuring the density of the semi-cured honeycomb sheet, repeating the above process for multiple times, and measuring the density of the semi-cured honeycomb sheet to enable the honeycomb to reach the target density and keep the flexibility;
and S3, selecting a set of die, paving and adhering the honeycomb section, and then carrying out high-temperature curing in an oven.
2. The preparation method of the semi-cured flexible aramid honeycomb core material according to claim 1, wherein in the step S2, the dipping process is that a honeycomb piece is soaked in a glue tank filled with phenolic resin for 5-6min to fully soak glue solution, then the glue solution is vertically extracted from a cell, and an air knife is used for blowing the redundant glue solution after the aramid honeycomb piece is discharged from the glue solution; in the curing process, the horizontal state of the cells is kept, circulating air passes through the cells and is put into an oven, the temperature rise rate is 3-5 ℃/min, the constant-temperature heat preservation temperature is 120 +/-2 ℃ except for final semi-curing, the constant-temperature heat preservation temperature is 100 +/-2 ℃ during final semi-curing, and the constant-temperature heat preservation time is always 30min +/-3 min.
3. The preparation method of the semi-cured flexible aramid honeycomb core material according to claim 1, wherein the dipping and semi-curing process in the step S2 comprises multiple times to achieve uniform distribution of the phenolic resin, the final time constant-temperature heat preservation temperature is 100 ℃ plus or minus 2 ℃, the other times constant-temperature heat preservation temperature is 120 ℃ plus or minus 2 ℃, the constant-temperature heat preservation time is 30min plus or minus 3min, and the temperature is reduced to room temperature 30min-45min after the single time constant-temperature heat preservation.
4. The preparation method of the semi-cured flexible aramid honeycomb core material according to claim 1, characterized in that the aramid honeycomb sheet in the step S1 is prepared by shaping an unimpregnated aramid honeycomb block and high-speed sheet cutting by a high-precision horizontal band sawing machine.
5. The method for preparing the semi-solidified flexible aramid honeycomb core material according to claim 1, wherein the thickness of the aramid honeycomb sheet in the step S1 is 3-50mm, the nominal cell side lengths are 1.83mm, 2.75mm, 4.80mm, 5.70mm and 7.20mm, and the nominal density is 18 kg/m-48 kg/m for carrying out the forging.
6. The method for preparing the semi-cured flexible aramid honeycomb core material according to claim 1, wherein in the step S3, the core material is cured independently along with the mold, the semi-cured flexible aramid honeycomb core material is paved on the surface of the mold in a paving manner, the non-sticky release material is paved on the surface of the mold, the high-temperature vacuum film is paved on the semi-cured flexible aramid honeycomb core material, the non-sticky release material is paved on the surface of the mold, the honeycomb core material is tightly adhered to the mold after the vacuum pumping, the target shape is kept, and the vacuum degree is-0.03 MPa to-0.05 MPa.
7. The preparation method of the semi-solidified flexible aramid honeycomb core material as claimed in claim 1, wherein the temperature rise rate in the step S3 includes two kinds of rates of 2 ℃ -3 ℃/min and 5 ℃ -7 ℃/min, and the constant temperature holding temperature includes two stages of 120 ℃ ± 2 ℃ and 175 ℃ ± 5 ℃; the curing process comprises the steps of heating the room temperature to 120 +/-2 ℃ at the speed of 2-3 ℃/min in the first stage, keeping the temperature constant for 120 +/-5 min, continuously heating the room temperature to 175 +/-3 ℃ from 120 ℃ in the second stage at the speed of 5-7 ℃/min, keeping the temperature constant for 45 +/-3 min, and cooling the room temperature after the constant temperature is kept for 60-90 min.
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| Application Number | Priority Date | Filing Date | Title |
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| CN202211225128.9A CN115609948A (en) | 2022-10-09 | 2022-10-09 | Preparation method of semi-cured flexible aramid fiber honeycomb core material |
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| CN202211225128.9A CN115609948A (en) | 2022-10-09 | 2022-10-09 | Preparation method of semi-cured flexible aramid fiber honeycomb core material |
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| CN202211225128.9A Pending CN115609948A (en) | 2022-10-09 | 2022-10-09 | Preparation method of semi-cured flexible aramid fiber honeycomb core material |
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