A method for forming a honeycomb core of continuous fibers

Abstract

The present application belongs to the technical field of composite material manufacturing, and relates to a honeycomb core material cell shaping method with high temperature resistance. The present application realizes the shaping operation of the continuous fiber honeycomb core material by introducing the special polyimide resin spraying and resin solution soaking method under the premise of not changing the existing honeycomb core material preparation process, avoids the disadvantage that the traditional method for preparing the continuous fiber honeycomb core material cannot perform the cell shaping operation and can only adopt the tooling to maintain the honeycomb cell size, and reduces the honeycomb impregnation process difficulty, improves the performance stability and preparation efficiency of the honeycomb, and reduces the price manufacturing cost. Meanwhile, the performance of the continuous fiber honeycomb core material prepared by the present application is obviously higher than that of the traditional aramid paper honeycomb and aluminum honeycomb, and the temperature resistance grade is high, so that the continuous fiber honeycomb core material can be widely applied to the hypersonic aircraft, high altitude missile body, rocket shell and high temperature engine parts.

Description

Technical Field

[0001] This invention belongs to the field of composite material manufacturing technology and relates to a method for shaping the pores of a high-temperature resistant continuous fiber honeycomb core material. This method utilizes a special process to shape the pores of the continuous fiber honeycomb core material, avoiding the need for impregnation with tooling. This method is applicable to a wide range of continuous fiber types, including carbon fiber fabrics, glass fiber fabrics, quartz fiber fabrics, and aramid fiber fabrics, all of which can be used to shape the pores of the honeycomb core material. The resulting honeycombs exhibit good dimensional stability and high production efficiency. Background Technology

[0002] Honeycomb core materials, due to their superior properties such as high specific strength and high specific stiffness, are widely used in the aerospace, aviation, and rail transportation fields. The shaping process of honeycomb core materials can significantly reduce the difficulty of the impregnation process and improve production efficiency. For aramid paper honeycomb core materials, shaping does not require special treatment; simply placing the stretched honeycomb at a high temperature, heating it to near the glass transition temperature of aramid, achieves shaping and ensures dimensional stability. Aluminum honeycomb core materials, due to the deformation-retaining ability of their main raw material, aluminum foil, only require opening the honeycomb cells to ensure that the cell size does not change. However, honeycomb core materials made from continuous fibers cannot be shaped because there is no resin bonding between the fibers. They can only be shaped using tooling to ensure that the cell size does not change, but the addition of tooling introduces many process and efficiency problems, such as the inability to produce large-height honeycomb core materials and poor dimensional stability. Therefore, inventing a method for shaping the cell structure of continuous fiber honeycomb core materials is of great significance. Summary of the Invention

[0003] This invention proposes a method for shaping the lattice of high-temperature resistant continuous fiber honeycomb core material. This method achieves the shaping of the lattice of continuous fiber honeycomb core material through special process treatment, avoiding the honeycomb impregnation operation with tooling, and improving the dimensional stability and production efficiency of continuous fiber honeycomb core material.

[0004] This invention achieves cell sizing of high-temperature resistant continuous fiber honeycomb core material through the following scheme: A method for shaping the lattice of a high-temperature resistant continuous fiber honeycomb core material includes the following steps: Step 1: Pretreatment of continuous fibers for honeycomb preparation: Unwind the fiber fabric, spray the polyimide resin solution evenly onto the surface of the fiber fabric, then transfer the fiber fabric to an oven to dry the solvent in the resin solution at a certain temperature, and then rewind the fiber fabric for later use.

[0005] Step 2: Following the traditional preparation method of aramid paper honeycomb, a polyimide-based core adhesive is used to gravure-coat the fiber fabric. The adhesive viscosity range is 50~240 cP. After coating, the core adhesive is dried within the range of 80~240℃. After drying, the carbon fiber plain weave fabric is laminated and cured by high-temperature pressing. The high-temperature pressing process is as follows: pressing pressure per unit area ranges from 0.1 to 1.2 MPa, pressing temperature is 240℃~300℃, and holding time is 120~600 min, thus obtaining the honeycomb laminated board.

[0006] Step 3: Pre-stretch the honeycomb laminate, then immerse the pre-stretched honeycomb laminate in a resin solution. After immersion, squeeze out the excess resin solution, remove the laminate, and then stretch the laminate to the required size on a honeycomb stretching machine.

[0007] Step 4: Place the stretched continuous fiber honeycomb core material into a high-temperature oven and perform a shaping process on the honeycomb at high temperature.

[0008] Step 5: Following the traditional impregnation method for aramid paper honeycomb, the continuous fiber honeycomb core material is repeatedly impregnated to obtain the continuous fiber honeycomb core material.

[0009] The solvent for the pretreated polyimide resin solution in step 1 is one or more of ethanol, dimethylformamide, and acetone, and the solid content of the resin solution is between 1% and 15%.

[0010] The solvent drying temperature in step 1 is 35℃~350℃, and the drying time is 15min~60min.

[0011] The continuous fiber mentioned in step 1 is one of carbon fiber fabric, glass fiber fabric, quartz fiber fabric and aramid fiber fabric.

[0012] The continuous fiber in step 1 is a plain weave fabric or a twill weave fabric.

[0013] The resin solution in step 3 is a polyimide resin, which is the same type of polyimide resin used in the pretreatment in step 1.

[0014] The solid content of the polyimide resin solution in step 3 is 20% to 60%.

[0015] The polyimide resin monomer in step 3 consists of a capping agent, a dianhydride, and a diamine. Phenylacetyl phthalic anhydride (4-PEPA) is the capping agent, and asymmetric isomeric biphenyl dianhydride (a-BPDA) has a dianhydride structure. The dianhydride and capping agent are esterified and then polycondensed with the diamine to obtain the final product.

[0016] After soaking in the resin solution in step 3, the amount of adhesive applied is 1 kg / m3 to 10 kg / m3.

[0017] The shaping treatment temperature in step 4 is 200℃~400℃, and the treatment time is 5min~45min.

[0018] Features and beneficial effects of the present invention: This invention relates to a cell-grid shaping method. Without altering existing honeycomb core material manufacturing processes, it introduces a special combination of polyimide resin spraying and resin solution immersion to achieve cell-grid shaping of continuous fiber honeycomb core materials. This avoids the drawbacks of traditional methods, which cannot perform cell-grid shaping and rely on tooling to maintain cell dimensions. Implementing this method in the continuous fiber honeycomb core material manufacturing process reduces the difficulty of the honeycomb impregnation process, improves the performance stability and manufacturing efficiency of the honeycomb, and lowers manufacturing costs. Furthermore, the continuous fiber honeycomb core material prepared by this method exhibits significantly higher performance than traditional aramid paper honeycomb and aluminum honeycomb, and has a higher temperature resistance, making it widely applicable in hypersonic aircraft, high-speed missile bodies, rocket casings, and high-temperature engine components. Attached Figure Description

[0019] Figure 1 Flowchart of high-temperature resistant continuous fiber honeycomb core material lattice shaping process; The components include: 1. Polyimide resin solution; 2. Fiber fabric; 3. Treated fiber fabric; 4. Core strip adhesive; 5. Continuous fiber honeycomb laminate; 6. Polyimide shaping resin; 7. Stretched honeycomb; 8. Oven. Figure 2 : A schematic diagram of a honeycomb structure. Detailed Implementation

[0020] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments: A method for shaping the lattice of a high-temperature resistant continuous fiber honeycomb core material includes the following steps: Step 1: Pretreatment of continuous fibers for honeycomb preparation: Unwind the fiber fabric, uniformly spray the polyimide resin solution onto the surface of the fiber fabric, then transfer the fiber fabric to an oven to dry the solvent in the resin solution at a certain temperature, and then rewind the fiber fabric for later use. The solvent of the pretreated polyimide resin solution is one or more of ethanol, dimethylformamide, and acetone, and the solid content of the resin solution is between 1% and 15%.

[0021] The solvent drying temperature is 35℃~350℃, and the drying time is 15min~60min.

[0022] The continuous fiber is one of carbon fiber fabric, glass fiber fabric, quartz fiber fabric and aramid fiber fabric.

[0023] The continuous fiber is a plain weave fabric or a twill weave fabric.

[0024] Step 2: Following the traditional preparation method of aramid paper honeycomb, a polyimide-based core adhesive is used to gravure-coat the fiber fabric. The adhesive viscosity range is 50~240 cP. After coating, the core adhesive is dried within the range of 80~240℃. After drying, the fiber fabric is laminated and cured by high-temperature pressing. The high-temperature pressing process is as follows: pressing pressure per unit area ranges from 0.1 to 1.2 MPa, pressing temperature is 240℃~300℃, and holding time is 120~600 min, thus obtaining the honeycomb laminated board.

[0025] Step 3: Pre-stretch the honeycomb laminate, then immerse the pre-stretched honeycomb laminate in a resin solution. After immersion, squeeze out the excess resin solution, remove the laminate, and then stretch the laminate to the required size on a honeycomb stretching machine.

[0026] The resin solution is a polyimide resin, which is the same type of polyimide resin used in the pretreatment step 1.

[0027] The solid content of the polyimide resin solution is 20% to 60%.

[0028] The polyimide resin monomer comprises a capping agent, a dianhydride, and a diamine. Phenylacetyl phthalic anhydride (4-PEPA) is the capping agent, and asymmetric isomeric biphenyl dianhydride (a-BPDA) has a dianhydride structure. The polyimide is prepared by esterifying the dianhydride and capping agent with a low-boiling-point alcohol as the polymerization solvent, followed by a polycondensation reaction with the diamine.

[0029] After soaking in the resin solution, the amount of adhesive applied is 1 kg / m3 to 10 kg / m3.

[0030] Step 4: Place the stretched continuous fiber honeycomb core material into a high-temperature oven for high-temperature shaping treatment. The shaping treatment temperature is 200℃~400℃, and the treatment time is 5min~45min.

[0031] Step 5: Following the traditional impregnation method for aramid paper honeycomb, the continuous fiber honeycomb core material is repeatedly impregnated to obtain the continuous fiber honeycomb core material.

[0032] Example 1 like Figure 1As shown, a high-temperature resistant continuous fiber honeycomb core material uses polyimide resin solution 1 with water as the solvent and a resin content of 10%. The fiber fabric 2 is a carbon fiber plain weave fabric with an areal density of 120 g / m2. The polyimide setting resin 6 uses alcohol as the solvent and has a resin content of 20%. The specific setting process is as follows: Step 1: Pretreatment of carbon fiber plain weave fabric: Unwind the fiber fabric 2 and spray polyimide resin solution 1 onto the surface of the fiber fabric 2, repeating twice until the polyimide resin solution 1 evenly covers the surface of the fiber fabric 2. Then, transfer the fiber fabric 2 to an oven and dry it at 100℃ for 10 minutes, followed by drying at 180℃ for 5 minutes. After the solvent in the polyimide resin solution 1 is dried, rewind the fiber fabric for later use. After pretreatment, the areal density of the carbon fiber plain weave fabric increases by 8±1 g / m2.

[0033] Step 2: Select a coating roller with a grid side length of 2.75mm, and use polyimide core strip adhesive 4 to gravure-coat the fiber fabric 2 according to the traditional aramid paper honeycomb preparation method. The adhesive viscosity is 160cp. After coating, the core strip adhesive is dried at 80℃. After drying, the carbon fiber plain weave fabric is laminated and high-temperature pressed for curing. The high-temperature pressing process is as follows: pressing pressure 0.8MPa, pressing temperature 260℃, and holding time 360min, to prepare the honeycomb laminated board.

[0034] Step 3: Pre-stretch the honeycomb laminate along the W direction to the diameter of the inscribed circle of the honeycomb (see...). Figure 2 After the thickness reaches approximately 1.5mm and all honeycomb cells are confirmed to be free of adhesion, the pre-stretched honeycomb laminate is immersed in polyimide shaping resin 6 (10% solids content) for 30 minutes. After immersion, excess resin solution is squeezed out until no resin drips. The laminate is then stretched on a honeycomb stretching machine until the diameter of the inscribed circle of the honeycomb (see...) is reached. Figure 2 Stop stretching when the diameter reaches the range of 4.29~5.24mm.

[0035] Step 4: Place the stretched continuous fiber honeycomb core material into a high-temperature oven and perform a shaping treatment at 320℃ for 30 minutes. The resulting honeycomb exhibits high dimensional accuracy and dimensional stability within 3%.

[0036] Step 5: Following the traditional impregnation method for aramid paper honeycomb, the continuous fiber honeycomb core material is repeatedly impregnated six times to obtain a continuous fiber honeycomb core material with a cell side length of 2.75 mm and a prefabricated density of 80 kg / m³. The resin used for impregnation is polyimide resin with a resin solids content of 38%. Subsequently, the honeycomb core material is placed in a high-temperature oven and the polyimide resin is cured at 380°C for 240 minutes to obtain a high-temperature resistant honeycomb core material. The strength retention rate of this honeycomb at 350°C is ≥60%, and the strength retention rate at 400°C is ≥40%.

[0037] Example 2 like Figure 1 As shown, a high-temperature resistant continuous fiber honeycomb core material is used. The polyimide solution 1 uses water as the solvent and has a resin content of 5%. The fiber fabric 2 is a plain weave glass fiber fabric with an areal density of 60 g / m2. The polyimide setting resin 6 uses alcohol as the solvent and has a resin content of 30%. The specific setting process is as follows: Step 1: Pretreatment of the glass fiber plain weave fabric: Unwind the glass fiber fabric and spray polyimide resin solution 1 onto the surface of the fiber fabric 2, repeating 3 times until the polyimide resin solution 1 evenly covers the fabric surface. Then, transfer the fiber fabric 2 to an oven and dry it at 100℃ for 5 minutes, followed by drying at 180℃ for 5 minutes. After the solvent in the polyimide resin solution 1 has dried, rewind the fiber fabric 2 for later use. After pretreatment, the areal density of the glass fiber plain weave fabric increases by 3±1 g / m³. 2 .

[0038] Step 2: Select a coating roller with a grid side length of 3.0 mm, and use polyimide core strip adhesive 4 to gravure-coat the fiber fabric 2 according to the traditional aramid paper honeycomb preparation method. The adhesive viscosity is 90 cp. After coating, dry the core strip adhesive at 80℃. After drying, laminate and high-temperature press the glass fiber plain weave fabric. The high-temperature pressing process is as follows: pressing pressure 0.7 MPa, pressing temperature 300℃, and holding time 420 min to prepare the honeycomb laminated board.

[0039] Step 3: Pre-stretch the honeycomb laminate along the W direction to the diameter of the inscribed circle of the honeycomb (see...). Figure 2 Once the diameter reaches approximately 1.8 mm, confirming that all honeycomb cells are free of adhesion, the pre-stretched honeycomb laminate is then immersed in polyimide shaping resin 6 (5% solids content) for 20 minutes. After immersion, excess resin solution is squeezed out until no resin drips. The laminate is then stretched on a honeycomb stretching machine. Stretching is stopped when the diameter of the inscribed circle of the honeycomb reaches the range of 4.68~5.72 mm.

[0040] Step 4: Place the stretched continuous fiber honeycomb core material into a high-temperature oven and perform a shaping treatment at 320℃ for 60 minutes. The resulting honeycomb exhibits high dimensional accuracy and dimensional stability within 2.5%.

[0041] Step 5: Following the traditional impregnation method for aramid paper honeycomb, the continuous fiber honeycomb core material is repeatedly impregnated to obtain a continuous fiber honeycomb core material with a cell side length of 3.0 mm and a pre-fabricated density of 48 kg / m³. The resin used for impregnation is polyimide resin with a resin solids content of 30%. Subsequently, the honeycomb core material is placed in a high-temperature oven and the polyimide resin is cured at 380℃ for 240 min to obtain a high-temperature resistant honeycomb core material. The strength retention rate of this honeycomb at 350℃ is ≥60%, and the strength retention rate at 400℃ is ≥40%.

[0042] Example 3 like Figure 1 As shown, a high-temperature resistant continuous fiber honeycomb core material is used. The polyimide solution 1 uses water as the solvent and has a resin content of 8%. The fiber fabric 2 is a carbon fiber twill fabric with an areal density of 110 g / m2. The polyimide setting resin 6 uses alcohol as the solvent and has a resin content of 40%. The specific setting process is as follows: Step 1: Pretreatment of carbon fiber twill fabric: Unwind the fiber fabric 2 and spray polyimide resin solution 1 onto the surface of the fiber fabric 2, repeating 4 times until the polyimide resin solution 1 evenly covers the fabric surface. Then, transfer the fiber fabric 2 to an oven and dry it at 100℃ for 15 minutes, followed by drying at 180℃ for 12 minutes. After the solvent in the polyimide resin solution 1 is dried, rewind the fiber fabric 2 for later use. After pretreatment, the areal density of the carbon fiber twill fabric increases by 6±1 g / m2.

[0043] Step 2: Select a coating roller with a grid side length of 5.5mm, and use a polyimide core strip adhesive to gravure-coat the fiber fabric 2 according to the traditional aramid paper honeycomb preparation method. The adhesive viscosity is 120cp. After coating, the core strip adhesive is dried at 100℃. After drying, the carbon fiber twill fabric is laminated and high-temperature pressed for curing. The high-temperature pressing process is as follows: pressing pressure 0.5MPa, pressing temperature 265℃, and holding time 240min, to prepare the honeycomb laminated board.

[0044] Step 3: Pre-stretch the honeycomb laminate along the W direction to the diameter of the inscribed circle of the honeycomb (see...). Figure 2Once the diameter reaches approximately 3.2 mm, confirming that all honeycomb cells are free of adhesion, the pre-stretched honeycomb laminate is then immersed in polyimide shaping resin 6 (35% solids content) for 15 minutes. After immersion, excess resin solution is squeezed out until no resin drips. The laminate is then stretched on a honeycomb stretching machine. Stretching is stopped when the diameter of the inscribed circle of the honeycomb reaches the range of 8.57~10.48 mm.

[0045] Step 4: Place the stretched continuous fiber honeycomb core material into a high-temperature oven and perform a shaping treatment at 350℃ for 60 minutes. The resulting honeycomb exhibits high dimensional accuracy and dimensional stability within 3%.

[0046] Step 5: Apply the traditional impregnation method for aramid paper honeycomb to the continuous fiber honeycomb core material. The resin was repeatedly impregnated six times to obtain a grid with a side length of 5.5 mm and a pre-fabricated density of 56 kg / m³. 3 A continuous fiber honeycomb core material was prepared, with polyimide resin used for impregnation and a resin solids content of 45%. Subsequently, the honeycomb core material was placed in a high-temperature oven and the polyimide resin was cured at 380°C for 240 minutes to obtain a high-temperature resistant honeycomb core material. The strength retention rate of this honeycomb at 350°C was ≥60%, and the strength retention rate at 400°C was ≥40%.

Claims

1. A method for shaping the pore structure of a high-temperature resistant continuous fiber honeycomb core material, characterized in that, Includes the following steps: Step 1: Pretreatment of continuous fibers for honeycomb preparation: The continuous fiber is one of carbon fiber fabric, glass fiber fabric, quartz fiber fabric and aramid fiber fabric. The fiber fabric is unwound and opened, and a polyimide resin solution is evenly sprayed onto the surface of the fiber fabric. Then the fiber fabric is transferred to an oven to dry the solvent in the resin solution. Finally, the fiber fabric is rolled up for use. The solvent of the pretreated polyimide resin solution is one or more of ethanol, dimethylformamide and acetone, and the solid content of the resin solution is between 1% and 15%. Step 2: Apply polyimide core strip adhesive to the fiber fabric using gravure printing. The adhesive viscosity range is 50~240 cP. After application, dry the core strip adhesive at 80~240℃. After drying, stack the fiber fabric and press it at high temperature for curing. The glass transition temperature Tg after curing is ≥350℃. The high-temperature pressing process is as follows: pressing pressure per unit area range is 0.1~1.2 MPa, pressing temperature is 240℃~300℃, and holding time is 120~600 min. A honeycomb laminate is then prepared. Step 3: Pre-stretch the honeycomb laminate along the W direction to 1 / 4 to 1 / 2 of the inscribed circle diameter of the honeycomb, ensuring that all honeycomb cells are free from adhesion. Then, immerse the pre-stretched honeycomb laminate in a resin solution. After immersion, use a circular pressure roller (weighing 20-50 kg) to squeeze out excess resin solution. Stretch the laminate to the required dimensions on a honeycomb stretching machine. The polyimide resin solution has a solid content of 20% to 60%, and the adhesive application rate after immersion is 1 kg / m³ to 10 kg / m³. This resin is the same as the polyimide resin pretreated in Step 1. The polyimide resin monomer consists of a capping agent, dianhydride, and diamine. The capping agent is phenylacetyl phthalic anhydride 4-PEPA, and the dianhydride is asymmetric isomeric biphenyl dianhydride α-BPDA. Low-boiling alcohols are used as polymerization solvents. The dianhydride and capping agent are esterified and then polycondensed with diamine to obtain the final product. Step 4: Place the stretched continuous fiber honeycomb core material into a high-temperature oven to set the honeycomb shape at high temperature; Step 5: Repeatedly impregnate the continuous fiber honeycomb core material with resin to obtain the continuous fiber honeycomb core material.

2. The method for shaping the pore structure of high-temperature resistant continuous fiber honeycomb core material according to claim 1, characterized in that, In step 1, the solvent drying temperature is 35℃~350℃, and the drying time is 15min~60min.

3. The method for shaping the pore structure of high-temperature resistant continuous fiber honeycomb core material according to claim 1, characterized in that, The continuous fibers in step 1 are plain weave or twill weave fabrics.

4. The method for shaping the pore structure of high-temperature resistant continuous fiber honeycomb core material according to claim 1, characterized in that, In step 4, the shaping treatment temperature is 200℃~400℃, and the treatment time is 5min~45min.

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