A composite material forming method with a front and rear end hollow rotating body structure

Abstract

The present invention provides a composite material forming method with a front and rear end hollow rotating body structure. First, perform die splitting at the junction between the front end and the main body of the mold, and keep the rear end integrated with the main body; assemble the split molds, clean the molds, and coat them with a hole-sealing agent and a release agent; lay a layer of prepreg as a process layer; place prepreg round bars at the structural rounded corners on the prepreg process layer, and place auxiliary materials for vacuum pre-compaction; lay the cut prepreg sheets on the mold; perform vacuum pre-compaction treatment during the laying process; cut the uniform pressure plate, and after cutting, lay a layer of adhesive release cloth; make the wiped uniform pressure plate contact the laid prepreg; wrap the rubber strip with an isolation film and fix it at the rounded corners on the laid prepreg; lay auxiliary materials on the surface of the uniform pressure plate and evacuate; perform hot pressing and curing, remove the auxiliary materials, the metal uniform pressure plate, and the rubber pressing strip, and remove the upper cover to complete product demolding. The present invention can obtain smooth and flat inner and outer surfaces.

Description

Technical Field

[0001] The present invention belongs to the technical field of composite material forming, and particularly relates to a composite material forming method for a hollow rotating body structure with front and rear ends. Background Art

[0002] Due to its characteristics of light weight and high strength, carbon fiber composite materials have been widely used in the aerospace field. The hollow rotating body structure with end faces is a commonly used connection structure form. The traditional forming method for its composite parts is male mold paving combined with autoclave bag pressing process, which cannot guarantee the dimensional accuracy and flatness of both sides of the product.

[0003] The patent "A Forming Method for a Rotating Body Composite Component" with the patent number CN110815851A proposes a secondary flipping treatment after prepreg paving for the rotating body product structure, and finally uses a special vacuum bag for encapsulation and curing. This method has good feasibility for the pure rotating body structure with a large length-diameter ratio, but poor operability for the rotating body structure with end faces.

[0004] The patent "A Composite Material Rotating Structure and Its Forming Method" with the patent number CN107696523A proposes an integrated composite lightweight design for the cone-column integrated structure, and obtains the product through automatic fiber placement on the male mold and autoclave bag pressing and curing. It is difficult to control the appearance quality of the bag pressing surface by this method.

[0005] The patent "A Rapid Integral Low-Cost Manufacturing Method for a Hollow Rotating Body Composite Material Structure" with the patent number CN201711444677.4 proposes using a non-metallic material as a mold to form and prepare a rotating body composite material structure, focusing on the change of the mold material, and curing the product by the vacuum bag autoclave method.

[0006] Therefore, for the hollow rotating body structure with front and rear ends, a method of using a metal female mold combined with a thin metal equalizing plate and a soft rubber for auxiliary pressurization is proposed to perform autoclave bag pressing and curing, so as to prepare a product with high dimensional accuracy, smooth and flat both sides, and good appearance quality. Summary of the Invention

[0007] The purpose of the present invention is to provide a composite material forming method for a hollow rotating body structure with front and rear flanges, which uses a metal female mold for forming, adds a process layer treatment, and combines a thin metal equalizing plate and a soft rubber strip for joint auxiliary pressurization to obtain smooth and flat inner and outer surfaces.

[0008] The technical solution for realizing the purpose of the present invention is as follows:

[0009] A composite material forming method for a hollow rotating body structure with front and rear flanges, comprising the following steps:

[0010] Step 1: Use a metal mold, perform parting on the mold at the junction of the front end and the main body, and keep the rear end integrated with the main body;

[0011] Step 2: Assemble the split mold, clean the mold, and apply a hole-sealing agent and a release agent on the laying surface of the mold;

[0012] Step 3: Lay a layer of prepreg on the laying surface of the mold as the process layer;

[0013] Step 4: After the laying of the prepreg process layer is completed, place a prepreg round bar at the structural fillet on the prepreg process layer. Then, place a hole isolation film and a breather felt on the surface of the prepreg in sequence, and use a vacuum bag to seal the bag and perform vacuum pre-compaction treatment;

[0014] Step 5: After the pre-compaction of the process layer is completed, continue to lay the cut prepreg sheets on the mold according to the laying angle in sequence until the laying is completed; during this laying process, perform vacuum pre-compaction treatment every few layers;

[0015] Step 6: Cut the uniform pressure plates separately according to the three parts of the front end face, the main body, and the rear end face of the mold. After cutting, lay a layer of adhesive release cloth on the surface of the three parts of the uniform pressure plates respectively, and wipe them clean;

[0016] Step 7: Make the side of the wiped uniform pressure plate covered with the adhesive release cloth contact the laid prepreg;

[0017] Step 8: Wrap the rubber strip with an isolation film and fix it at the fillet on the laid prepreg, and use it in cooperation with the uniform pressure plate;

[0018] Step 9: Lay a non-porous isolation film and a breather felt on the surface of the uniform pressure plate in sequence to completely cover the surface, and use a vacuum bag to seal the entire system of the mold and the prepreg and perform vacuum pumping;

[0019] Step 10: Perform hot pressing and curing on the vacuum bag - mold system with the vacuum degree meeting the requirements;

[0020] Step 11: After curing is completed, remove the placed isolation film, breather felt, vacuum bag, metal uniform pressure plate, and rubber pressure strip, and remove the upper cover to complete product demolding.

[0021] Compared with the prior art, the remarkable advantages of the present invention are:

[0022] Increase the process layup, without damaging the original design layup, and improve the feasibility of the process; use a thin-walled aluminum uniform pressure plate with a thickness ≤ 1 mm and soft rubber to jointly assist in pressurization to obtain a product with a flat and smooth inner and outer surfaces, and there are no defects such as poor resin content and lack of resin at the fillet of the product, such as Figure 3 . It can meet the molding of products with high requirements for product size and overall appearance, and reduce costs and process complexity. Brief Description of the Drawings

[0023] Figure 1 This is a schematic diagram of the female mold bag pressing and forming mold for the product in the present invention, which is mainly divided into three parts: the front end of the mold, the main body of the mold, and the rear end of the mold. Among them, the main body of the mold and the rear end are integrated, and the front end of the mold is an assembled structure.

[0024] Figure 2 This is a schematic diagram of the laying diagram and the combined auxiliary pressure placement of the thin-walled uniform pressure plate and soft rubber in the present invention.

[0025] Figure 3 This is a partial external view of the obtained product. Detailed Embodiments

[0026] The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments.

[0027] Combined with Figure 1 、 Figure 2 A composite material forming method with a front and rear flanged hollow rotating body structure in this embodiment is realized through the following steps:

[0028] Step 1: Use a metal mold, and perform mold splitting at the junction of the front end and the main body of the mold. The rear end remains integrated with the main body. The structure is shown in the attached Figure 1 .

[0029] Step 2: After the split mold is assembled, first wipe the mold clean with acetone, and then coat the mold laying surface with a hole-sealing agent and a release agent 3 times in sequence, with an interval of 20 - 30 minutes between each coating.

[0030] Step 3: After the mold treatment is completed, first lay the prepreg process layer on the mold laying surface, with a laying angle of 0° and a laying number of 1 layer.

[0031] Step 4: After the prepreg process layer is laid, place a prepreg round bar with a diameter ≤ 3 mm at the structural fillet on the prepreg process layer. Then, place auxiliary materials such as a perforated separator film and a breather felt on the prepreg surface in sequence and use a vacuum bag to seal the bag. Evacuate to perform pre-compaction treatment. The pre-compaction time by evacuation is 15 min - 30 min, and the pre-compaction vacuum degree ≤ -60 kPa.

[0032] Step 5: After the pre-compaction of the process layer is completed, continue to lay the cut prepreg sheets on the mold in sequence according to the laying angle until the laying is completed. During this laying process, perform pre-compaction treatment by evacuation every 6 - 8 layers. The pre-compaction time is 15 min - 30 min, and the pre-compaction vacuum degree ≤ -60 kPa.

[0033] Step 6: Cut the thin-walled metal aluminum plate with a thickness ≤ 1 mm. The aluminum plate is cut into a ring for the main body part and rectangles for the front and rear end faces according to the flanged front end face of the mold, the unfolded circumferential surface of the main body, and the flanged rear end face. After cutting, lay a layer of adhesive release cloth on the surfaces of the three parts of the aluminum plate respectively and wipe them clean.

[0034] Step 7: Make the side of the wiped metal aluminum plate covered with the adhesive release cloth contact the pre-preg that has been laid.

[0035] Step 8: Wrap the soft rubber strip with a release film and fix it at the rounded corners on the pre-preg that has been laid with a tape resistant to 180 °C - 200 °C temperature. Use it in combination with the metal aluminum equalizing plate, see attachment Figure 2 .

[0036] Step 9: Finally, lay a non-porous release film and a breather felt on the surface of the equalizing plate in sequence to completely cover the surface, and use a vacuum bag to bag and encapsulate the entire system of the mold and the pre-preg and evacuate it to a vacuum. The vacuum degree ≤ -95 kPa, and the vacuum degree drops ≤ 2 kPa within 5 minutes.

[0037] Step 10: Put the vacuum bag - mold system with the required vacuum degree into the autoclave for curing.

[0038] Step 11: After curing, remove the auxiliary materials such as the placed release film, breather felt, and vacuum bag, the metal equalizing plate, and the rubber pressing strip, and remove the upper cover to complete the demolding of the product.

[0039] For the requirements of high appearance and dimensional requirements for the front and rear flanged hollow rotary body structure, a metal female mold is used for forming to ensure the dimensional accuracy of the product. Through the addition of a new process layer and the treatment of filling round bars, combined with the use of a metal thin-walled equalizing plate and a soft rubber pressing strip, a product with good dimensions and appearance is obtained. Figure 3 This is a partial appearance view of the product obtained in this embodiment, and the obtained surface is flat and no defects are generated at the rounded corners.

Claims

1. A composite material forming method with a front and rear end hollow rotating body structure, characterized in that, it includes the following steps: Step 1: Use a metal mold, and perform mold splitting at the junction of the front end and the main body of the mold, and the rear end remains integrated with the main body; Step 2: Assemble the split molds, clean the molds, and sequentially coat a hole-sealing agent and a release agent on the laying surface of the molds; Step 3: Lay a layer of prepreg on the laying surface of the mold as a process layer, the laying angle is 0°, and the laying number of layers is 1 layer; Step 4: After the laying of the prepreg process layer is completed, place a prepreg round bar with a diameter ≤ 3mm at the structural fillet on the prepreg process layer. Then, sequentially place a perforated separator film and a breather felt on the surface of the prepreg and use a vacuum bag to seal the bag, and evacuate to perform pre-compaction treatment; Step 5: After the pre-compaction of the process layer is completed, continue to lay the cut prepreg sheets on the mold according to the laying angle in sequence until the laying is completed; during this laying process, perform vacuum pre-compaction treatment every several layers; Step 6: Cut thin-walled metal aluminum equalizing plates with a thickness ≤ 1mm. The metal aluminum equalizing plates are respectively cut into a ring shape of the main body part and rectangles of the front and rear end faces according to the flanging of the front end face of the mold, the unfolded circumferential surface of the main body, and the flanging of the rear end face; after cutting, lay a layer of adhesive release cloth on the surfaces of the three parts of the metal aluminum equalizing plates respectively, and wipe them clean; Step 7: Make the side of the wiped metal aluminum equalizing plate covered with the adhesive release cloth contact the laid prepreg; Step 8: Wrap the rubber strip with a separator film and fix it at the fillet on the laid prepreg, and use it in cooperation with the metal aluminum equalizing plate; Step 9: Sequentially lay a non-perforated separator film and a breather felt on the surface of the metal aluminum equalizing plate to completely cover the surface, and use a vacuum bag to seal the entire system of the mold and the prepreg and evacuate; Step 10: Perform hot pressing and curing on the vacuum bag - mold system with the vacuum degree meeting the requirements; Step 11: After curing is completed, remove the placed separator film, breather felt, vacuum bag, metal aluminum equalizing plate and rubber pressing strip, and remove the upper cover to complete product demolding.

2. The composite material forming method with a front and rear end hollow rotating body structure according to claim 1, characterized in that, the hole-sealing agent and the release agent are each coated 3 times, and the interval between each coating is 20 - 30 minutes.

3. The composite material forming method with a front and rear end hollow rotating body structure according to claim 1, characterized in that, in Step 4, the vacuum pre-compaction time is 15 minutes - 30 minutes, and the pre-compaction vacuum degree ≤ -60 kPa.

4. The composite material forming method with a front and rear end hollow rotating body structure according to claim 1, characterized in that, in Step 5, during the laying process, vacuum pre-compaction treatment is performed every 6 - 8 layers.

5. The composite material forming method with a front and rear end hollow rotating body structure according to claim 1 or 4, characterized in that, in Step 5, the vacuum pre-compaction time is 15 minutes - 30 minutes, and the pre-compaction vacuum degree ≤ -60 kPa.

6. The composite material forming method with a front and rear end hollow rotating body structure according to claim 1, characterized in that, in Step 9, the vacuum degree of evacuation ≤ -95 kPa, and the vacuum degree drops ≤ 2 kPa within 5 minutes.

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