A method for preparing a pressure-resistant, sealing composite material oil pipeline

Abstract

This invention proposes a method for preparing a pressure-resistant and sealing composite material oil pipeline, capable of producing composite oil pipelines with excellent oil pressure resistance, impermeability, sealing performance, and internal quality, belonging to the field of composite material molding technology. High-temperature resistant bismaleimide resin matrix and carbon fiber reinforced composite material are selected as the main molding raw materials. The internal cavity of the oil pipe is formed using a tubular vacuum bag assisted molding process. To ensure the accuracy of the product's external surface and meet the assembly requirements with other components, a female mold layup autoclave molding method is adopted. To improve molding quality, a layup method of pre-laying followed by flipping is adopted. During pre-laying, a release film is added between the layers of material to be flipped to prevent adhesion. Flipping uses the twisted wire strips added near the edge of the mold as the flipping reference. Before flipping, the tubular vacuum bag is folded and placed into the mold groove. The prepared oil pipeline can both transport fuel medium and provide structural load-bearing function, making it a typical structural and functional integrated component.

Description

Technical Field

[0001] This invention belongs to the field of composite material product molding technology, and in particular relates to a method for preparing a structural-functional integrated component that needs to both withstand internal pressure and provide good sealing performance for conveying fuel medium, while also providing external load-bearing capacity. Background Technology

[0002] In recent years, with the rapid development of the aerospace industry, the lightweighting of weaponry and equipment has become a focus of widespread attention. For aircraft, lightweighting means achieving higher flight speeds and longer ranges. Therefore, the concept of integrated structure and function has emerged.

[0003] Composite materials, with their lightweight, high strength, and corrosion resistance, have been widely used in aerospace, automotive, and electronics communications, among other fields. Continuous fiber-reinforced resin-based composites, in particular, have a promising future. Traditional high-performance oil pipelines are typically made of alloy materials to ensure their pressure resistance and sealing performance. However, alloys have drawbacks such as high density and cost, which negatively impacts the pursuit of weight reduction and low-cost recycling. Summary of the Invention

[0004] In view of this, the purpose of this invention is to overcome the shortcomings of the prior art and provide a method for manufacturing an integrated structure-function oil pipeline that can both transport fuel medium and provide structural load-bearing function.

[0005] The technical solution of this invention:

[0006] A method for preparing a pressure-resistant, sealing composite material oil pipeline includes the following steps:

[0007] According to the designed layering scheme, the material sheets are laid on the mold, and a release film is added to the parts of each layer that need to be flipped.

[0008] When laying the sheet material, vacuum the air after every few layers until all the sheet material has been laid.

[0009] Place long twisted yarns near the edge of the mold as a reference for turning over;

[0010] Vacuum pre-compression is applied to the product, and the position of the twisted yarn is fixed.

[0011] After pre-compression, place a folded tubular vacuum bag into the groove of the product;

[0012] The outermost layer of material at the flange is flipped inward and overlapped together, with the position of the twisted yarn as the reference.

[0013] The other layers of material are laid out one by one and overlapped, with the overlap position of each layer staggered from the overlap position of the previous layer;

[0014] After each layer of material is laid out, pre-compression and shaping, wrinkle trimming, heating and curing, demolding, and surface finishing are carried out to obtain a pressure-resistant and sealing composite material oil pipeline.

[0015] Furthermore, the pre-pressing and shaping, wrinkle trimming, heat curing and demolding, and product surface finishing include:

[0016] Place the mold cover plate on top, bag and seal, and vacuum pre-press to shape;

[0017] Remove the top cover, trim the product, and fill any wrinkles with twisted yarn.

[0018] Replace the cover plate, bag and seal the product, and then place the whole thing into an autoclave for heating and curing.

[0019] Demolding;

[0020] Repair burrs and nodules on the product surface.

[0021] Furthermore, the isolation membrane is placed with the edge of the mold as a reference, covering the entire turning area.

[0022] Furthermore, after every few layers, a vacuum is evacuated for 15-20 minutes, and the vacuum level is not less than -90 kPa.

[0023] Furthermore, the twisted yarn extends 2-3 mm below the edge of the mold, and the twisted yarn is made of unidirectional prepreg with a width of 50-60 mm, with a length consistent with the length of the mold edge.

[0024] Furthermore, the product is vacuum-pre-compressed on a mold, with a perforated isolation membrane, a breathable felt, and a vacuum bag placed on top of the product in sequence. The vacuum bag is then bonded to the mold using sealing strips.

[0025] Furthermore, the length and cross-sectional perimeter of the tubular vacuum bag should be greater than the product length and cross-sectional arc length, and the tubular vacuum bag can withstand temperatures above 180°C.

[0026] Furthermore, the length of the overlap is controlled at 5-10mm, and the overlap positions of adjacent layers are staggered by 10-20mm.

[0027] Further, the process involves placing the mold cover plate, bagging and sealing, and vacuuming for pre-compression and shaping. The inside of the tubular vacuum bag is open to the atmosphere, and the outside is connected to the vacuum bag used for vacuuming at the port through a sealing strip. The process involves filling the wrinkles with twisted yarn until the wrinkles are filled. The process involves placing the cover plate again and bagging and sealing the bag. After bagging and sealing, the vacuum level should reach above -90 kPa.

[0028] The present invention also provides a pressure-resistant and sealing composite material oil pipeline prepared according to the above method.

[0029] The beneficial effects of this invention compared to the prior art are as follows:

[0030] (1) The present invention adopts the in-situ lay-up method of female mold, which ensures the accuracy of the product's outer surface and improves the molding quality;

[0031] (2) The present invention separates the material sheets by using a release film before turning, so as to avoid the material sheets sticking together and being difficult to peel after pre-compression.

[0032] (3) By controlling the overlap length and overlap position distance, this invention can ensure that the product will not thicken or increase in weight over a large area, and also ensure that the product has sufficient strength and rigidity.

[0033] (4) The present invention uses twisted wire strips placed near the edge of the mold as the turning benchmark. On the one hand, this can ensure the accuracy of the folding angle when turning each layer and improve the regularity; on the other hand, it can also make up for the weak mechanical properties of the edge of the oil pipe structure.

[0034] (5) This invention utilizes the advantages of composite materials and process design to realize the preparation of a lightweight oil pipeline with integrated structure and function;

[0035] (6) The present invention can adjust parameters such as the number of layers, laying direction, overlap length and overlap misalignment distance according to product structure and performance requirements to meet a wider range of product needs. Attached Figure Description

[0036] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings:

[0037] Figure 1 This is a schematic diagram of a composite material oil pipeline.

[0038] Figure 2 This is a schematic diagram of the forming tooling.

[0039] Figure 3 This is a schematic diagram of ply overlap. Detailed Implementation

[0040] The present invention will now be described in detail with reference to the accompanying drawings and embodiments. It should be noted that, unless otherwise specified, the embodiments and features described herein can be combined with each other.

[0041] This invention discloses a method for preparing a pressure-resistant, sealing composite material oil pipeline. The prepared composite material oil pipeline has the following shape: Figure 1 As shown, the molding tooling (molding mold) used is as follows: Figure 2 As shown, the preparation method is achieved through the following steps:

[0042] The first step is to lay the cut sheets onto the mold according to the product dimensions. A release liner is added to the areas where sheets need to be flipped to prevent them from sticking together. The sheets are continuous fiber-reinforced resin-based composite prepregs, preferably using carbon fiber reinforced composite material with high-temperature resistant bismaleimide resin as the main molding material.

[0043] The second step is to perform vacuuming and degassing every 3 layers of material during the layering process until all the material sheets are laid. 3 layers is the preferred setting, but other numbers of layers, such as 1, 2, or 4 layers, can also be used.

[0044] The third step is to place the pre-prepared long twisted yarn horizontally 2-3 mm below the edge of the mold.

[0045] The fourth step involves laying a porous release film, a breathable felt, and a vacuum bag on the product surface in sequence. The vacuum bag is then sealed and vacuumed to pre-compress the product.

[0046] Fifth step: After pre-compression is completed, fold the tubular vacuum bag and place it in the groove of the mold. This tubular vacuum bag is used to form the inner cavity of the oil pipeline, which is different from the vacuum bag used for pre-compression in the fourth step. Because of its large size, this tubular vacuum bag needs to be folded before it can be put into the groove.

[0047] Step 6: Apply the last layer (i.e., the outermost layer) to the folded edge. Figure 3 (As shown) The material sheets are laid inwards and overlapped together with the position of the twisted yarn as the reference, with an overlap length of 5-10mm.

[0048] Step 7: Lay the second-to-last layer of material in the same way as in step 6, except that the overlap position is staggered from the overlap position of the previous layer by 10-20mm.

[0049] Step 8: Repeat steps 6 and 7 to flip and lay the other layers of material one by one until all layers of material have been flipped. Figure 3 As shown.

[0050] Step nine involves placing the mold cover plate, sealing the product using a vacuum bag, and then vacuum-pressing for shaping. The tubular vacuum bag described in step five is open to the outside atmosphere, and its exterior is connected to the vacuum bag used for vacuuming using a sealing strip at the port, forming a sealed structure. This allows pressure to be applied to the prepreg through the tubular vacuum bag during vacuuming. The purpose of using a tubular vacuum bag is to transmit pressure to the prepreg during temperature curing and vacuuming, ensuring it adheres tightly to the mold and facilitating the formation of the tubular cavity.

[0051] Step 10: Remove the top cover and repair the product. Fill any wrinkles with twisted yarn until the wrinkles are smooth.

[0052] Step 11: Place the cover plate back on, bag and seal it as in step 9, and put the whole thing into an autoclave for heating and curing. During the vacuuming process, the vacuum level should reach above -90 kPa.

[0053] Step 12: After curing, remove from the can and demold.

[0054] Step 13: Repair any burrs and nodules on the product surface.

[0055] In one specific embodiment of the present invention, the method for preparing a pressure-resistant and sealing composite material pipe includes the following steps:

[0056] The first step is to lay the cut-out sheets on the mold according to the product size. For the overlapping parts between each layer of sheets, add a release film based on the edge of the mold and cover the entire overlapping area.

[0057] The second step is to vacuum the air every three layers of the material sheet until all the material sheets are laid. The vacuuming time is 15 minutes.

[0058] The third step is to lay all the sheets on the mold, and then place the pre-prepared long twisted filament horizontally 2mm below the edge of the mold. The twisted filament is made of unidirectional prepreg with a width of 50mm and a thickness of 0.125mm.

[0059] The fourth step involves laying a porous isolation film, a breathable felt, and a vacuum bag on the product surface in sequence. The vacuum bag is then sealed and vacuumed to pre-compress the product for 10 hours, with a pre-compression vacuum degree greater than -90 kPa.

[0060] Fifth step: After pre-compression, fold the tubular vacuum bag and place it in the groove of the mold, with each end of the vacuum bag extending 200mm.

[0061] Step 6: Fold the last layer of material at the edge inwards and overlap it with the twisted yarn position, with an overlap length of 5mm.

[0062] Step 7: Lay the second-to-last layer of material in the same way as in step 6, except that the overlap position is staggered from the overlap position of the previous layer by 15mm.

[0063] Step 8: Repeat steps 6 and 7 to flip and lay the other layers of material one by one until all layers of material are flipped and laid.

[0064] Step 9: Place the mold cover plate on top, bag the tubular vacuum bag, vacuum it, pre-compress and shape it. The inside of the tubular vacuum bag is open to the outside atmosphere, and the outside is connected to the vacuum bag used for vacuuming at the port with a sealing strip. The vacuuming time is 4 hours.

[0065] Step 10: Remove the top cover, repair the product, fill any wrinkles with twisted yarn, and smooth out the wrinkles.

[0066] Step 11: Place the cover plate back on, bag and seal it as in step 9, and put the whole thing into an autoclave for heating and curing. During the vacuuming process, the vacuum level should reach above -90KPa.

[0067] Step 12: After curing, remove the product from the can and demold it.

[0068] Step 13: Repair any burrs and nodules on the product surface.

[0069] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing a pressure-resistant and sealing composite material oil pipeline, the pressure-resistant and sealing composite material oil pipeline comprising a planar pipe wall and a semi-circular pipe wall connected to the planar pipe wall; the method comprising the following steps: According to the designed layering scheme, the material sheets are laid on the mold, and a release film is added to the parts of each layer that need to be flipped. When laying the sheet material, vacuum the air after every few layers until all the sheet material has been laid. Place long twisted yarns near the edge of the mold as a reference for turning over; Vacuum pre-compression is applied to the product, and the position of the twisted yarn is fixed. After pre-compression, place a folded tubular vacuum bag into the groove of the product; The outermost layer of material at the flange is flipped inward and overlapped together, with the position of the twisted yarn as the reference. The other layers of material are laid out one by one and overlapped, with the overlap position of each layer staggered from the overlap position of the previous layer; After each layer of material is laid out, pre-compression and shaping, wrinkle trimming, heat curing and demolding, and product surface finishing are carried out to obtain a pressure-resistant and sealing composite material oil pipeline. The process of pre-pressing and shaping, trimming wrinkles, heating and curing, demolding, and surface finishing includes: Place the mold cover plate on top, bag and seal, and vacuum pre-press to shape; Remove the top cover, trim the product, and fill any wrinkles with twisted yarn. Replace the cover plate, bag and seal the product, and then place the whole thing into an autoclave for heating and curing. Demolding; Repair burrs and nodules on the product surface.

2. The method for preparing a pressure-resistant sealing composite material oil pipeline according to claim 1, characterized in that: The isolation membrane is placed with the edge of the mold as a reference, covering the entire turning area.

3. The method for preparing a pressure-resistant, sealing composite material oil pipeline according to claim 1, characterized in that: The process involves vacuuming and venting every few layers for 15-20 minutes, with a vacuum level of not less than -90 kPa.

4. The method for preparing a pressure-resistant sealing composite material oil pipeline according to claim 1, characterized in that: The twisted wire is 2-3mm below the edge of the mold. The twisted wire is made of unidirectional prepreg with a width of 50-60mm and its length is consistent with the length of the edge of the mold.

5. The method for preparing a pressure-resistant, sealing composite material oil pipeline according to claim 1, characterized in that: The product is vacuum-pre-compressed on a mold, with a perforated isolation membrane, a breathable felt, and a vacuum bag placed on top of the product in sequence. The vacuum bag is then bonded to the mold using sealing strips.

6. The method for preparing a pressure-resistant, sealing composite material oil pipeline according to claim 1, characterized in that: The length and cross-sectional perimeter of the tubular vacuum bag should be greater than the product length and cross-sectional arc length, and the tubular vacuum bag should be able to withstand temperatures above 180°C.

7. The method for preparing a pressure-resistant, sealing composite material oil pipeline according to claim 1, characterized in that: The length of the overlap is controlled at 5-10mm, and the overlap positions of adjacent layers are staggered by 10-20mm.

8. The method for preparing a pressure-resistant sealing composite material oil pipeline according to claim 1, characterized in that: The process involves placing the mold cover plate on the tube, bagging and sealing it, and then vacuuming and pre-pressing it to shape. The inside of the tubular vacuum bag is open to the atmosphere, and the outside is connected to the vacuum bag used for vacuuming at the port through a sealing strip. The process involves filling the wrinkles with twisted yarn until the wrinkles are filled. The cover plate is then placed back on and the bag is sealed. After sealing, the vacuum level should reach above -90 kPa.

9. A pressure-resistant, sealing composite material oil pipeline prepared by the method according to any one of claims 1 to 8.

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