Method for manufacturing one-piece deep box-shaped part and deep box-shaped part thereof

Abstract

The present invention discloses a method for manufacturing an integrally formed deep box-shaped part and its deep box-shaped part, extracts the part's outer surface, prefabricates a female mold forming tool, lays a predetermined number of prepregs, and after the prepregs are laid, performs a vacuum pre-compacting treatment on the prepregs. During the vacuum pre-compacting process, soft silicone strips are filled in the female mold R corner area. After the vacuum pre-compacting treatment, a paving layer is formed. The surface fiber flatness of the paving layer is checked. When the surface fiber of the paving layer is uneven, the uneven paving layer needs to be scraped and pressed. When the surface fiber of the paving layer is flat, the prepreg is continued to be laid until all the layers are laid to form a deep box part of a predetermined shape. The groove of the deep box part is filled with rubber material, which is compacted and packaged in a vacuum bag and then hot-pressed. The present invention only requires a set of metal female mold forming tooling in combination with rubber material to complete the entire paving and hot-pressing curing molding, effectively controlling tooling costs.

Description

Technical Field

[0001] The invention belongs to the technical field of welding equipment, and particularly relates to a method for manufacturing an integrally formed deep box-shaped part and the deep box-shaped part. Background Art

[0002] Carbon fiber composites are increasingly used in the aviation industry due to their high specific strength, light weight, corrosion resistance, and fatigue resistance. Composite molding processes have also been continuously improved with the development of the manufacturing industry. Autoclave molding, compression molding, automated fiber / tape placement, RTM, VARI, and OOA processes are now being applied to various structural components. Traditional autoclave and compression molding processes are increasingly being used, with silicone rubber being widely used as a key auxiliary pressurizing material.

[0003] Small box-shaped structural parts are often used as butt joints in composite structural parts for military aircraft and unmanned aerial vehicles. Due to the constraints of aerodynamic shape and assembly requirements, box-shaped structural parts have high requirements for external surface quality. Therefore, a negative mold forming method is required during the curing process. Currently, the main molding methods for small negative mold box-shaped structural parts include compression molding, braided winding, and silicone rubber thermal expansion molding. Among them, small composite box-shaped parts prepared by compression molding and braided winding have high void ratios, poor lossless quality, serious thickness deviations, and mechanical properties that often fail to meet design requirements. Silicone rubber thermal expansion molding has been gradually applied to the manufacture of aerospace composite materials since the 1990s. It mainly relies on combination molds and expansion core mold molding. Not only is the mold cost high, but the product quality is also affected by multiple factors such as process clearance, core mold silicone rubber thickness, and combination mold positioning accuracy, resulting in poor product stability. Therefore, a low-cost, stable and reliable silicone rubber thermal expansion molding process is urgently needed to realize the manufacturing of small box-shaped structural parts. Summary of the Invention

[0004] Purpose of the invention: To provide a method for manufacturing an integrally formed deep box-shaped part and the deep box-shaped part thereof, thereby solving the above-mentioned problems existing in the prior art.

[0005] Technical solution: A method for manufacturing a one-piece deep box-shaped part includes the following steps:

[0006] Step 1: Extract the part's outer surface and prefabricate the negative mold forming tooling;

[0007] Step 2: Lay out a predetermined amount of prepreg. After the prepreg is laid out, place a soft silicone bead that matches the R angle size in the R angle area of ​​the female mold. After the soft silicone bead is placed, press the soft silicone bead with a tool to make it completely fit with the R angle. Then, vacuum pre-compact the prepreg and the soft silicone bead to obtain a paving layer.

[0008] Step 3: After the vacuum pre-compacting treatment in step 2 is completed, a paving layer is formed, and the surface fiber flatness of the paving layer is checked. If the surface fiber of the paving layer is flat, it is ready for further processing. If the surface fiber of the paving layer is uneven, the uneven paving layer needs to be scraped and pressed to flatten the uneven parts to obtain a paving layer with a flat surface fiber, which is ready for further processing.

[0009] Step 4: Repeat steps 2 and 3 until all the paving layers are completed to obtain a deep box part of a predetermined shape;

[0010] Step 5: Fill the groove of the deep box part in step 4 with rubber material. After placing the rubber material, press it to fully fill the groove, and scrape the rubber material so that the rubber material is flush with the groove opening. After compacting it and packaging it with a vacuum bag, the part to be cured is obtained. Then, the part to be cured is hot-pressed and cured to obtain a deep box-shaped part.

[0011] Preferably, step 1 is to extract the part's outer surface, and the specific process is as follows:

[0012] Step 1.1: Extract the shape of the part to be manufactured and prefabricate a metal female mold tooling. The metal female mold tooling is a split-flap modular tooling. The part includes at least a bottom plate and a peripheral side plate.

[0013] Step 1.2: Use Fibersim software to design the paving layer for the deep box-shaped part, and design the part base and perimeter into a petal structure.

[0014] Preferably, in step 2, a predetermined amount of prepreg is laid, and the specific process is as follows:

[0015] Step 2.1, laying up to three layers of prepreg into the female mold tooling to form a laying layer;

[0016] Step 2.2: Pre-pump the prepreg laid in step 2.1 at a pressure of 70kPa-90kPa for 5-8 minutes;

[0017] Step 2.3: In step 2.1, fill the R-corner area inside the female mold with a soft silicone strip, and press the soft silicone strip to make it fit tightly with the R-corner.

[0018] Preferably, in step 2.1, the process of laying the prepreg is as follows:

[0019] Step 2.11: The fibers of the base plate and the periphery are continuous in the R corner area of ​​the female mold base plate;

[0020] Step 2.12: Avoid the R-corner area of ​​the perimeter ply splicing. During the laying process, first secure the prepreg to the baseboard surface and apply scraping pressure to the prepreg, placing it on the baseboard surface and at the R-corner. Then, apply scraping pressure to the perimeter along the prepreg fiber direction, from the R-corner of the baseboard, toward the perimeter surface. If wrinkles form during laying, split the prepreg at the perimeter along the fiber direction and lay them together. The butt-cutting should avoid the R-corner of the perimeter. At this point, the prepreg fibers at the R-corner are continuous; ensure fiber continuity at the R-corner of the perimeter. Fibersim software can also be used to design the laying layers for deep box-shaped parts. Cut the prepreg in the blanking diagram so that the prepreg splicing avoids the R-corner during laying.

[0021] Preferably, in step 2.11, the paving layer design is performed for the deep box-shaped part using Fibersim software, and the prepreg is notched in the blanking drawing so that the splicing of the prepreg avoids the R corner during the paving process.

[0022] Preferably, the vacuum bag packaging in step 5.1 adopts envelope-type vacuum bag packaging.

[0023] Preferably, step 5, vacuum bag packaging, the specific process is as follows:

[0024] Step 5.1: The vacuum bag has at least one set of wrinkles at the contact position with the rubber material, and the expansion space of the wrinkles is larger than the expansion space of the rubber material;

[0025] Step 5.2: The expanded pressure of the rubber material squeezes the deep box-shaped part. When the expanded pressure of the rubber material is less than the tank pressure, the pressure transmitted to the deep box-shaped part is the tank pressure. When the expanded pressure of the rubber material is greater than the tank pressure, the pressure is released by squeezing the vacuum bag through the rubber material to achieve pressure balance. Then, the pressure transmitted to the deep box-shaped part is still the tank pressure.

[0026] An integrally formed deep box-shaped part is manufactured by the above method, comprising a base and side walls extending upward along the base; the side walls are integrally formed with the base, and the side walls are integrally connected to each other with a predetermined arc, and the side walls and the base form a hollow structure with an open top.

[0027] Beneficial effects: The present invention relates to a method for manufacturing an integrally formed deep box-shaped part and the deep box-shaped part thereof, which only requires a set of metal female mold forming tooling and rubber material to complete the entire laying and hot pressing curing forming, effectively controlling tooling costs;

[0028] Secondly, during the prepreg laying process, local pressure is applied to the R corner of the female mold by using a soft silicone strip, which can effectively avoid the problems of ply bridging in the R corner area of ​​the female mold and incomplete discharge of prepreg voids.

[0029] Finally, the cavity of the negative membrane groove is filled with rubber material, and the rubber material is vacuum-encapsulated with a vacuum bag, and the entire part is hot-pressed and cured. With the cooperation of the rubber material and the vacuum bag, the pressure is transmitted to the right place during the hot-pressing and curing process of the deep box-shaped parts. At the same time, the risk of overpressure during the curing process of the product due to excessive expansion of the rubber clay can be avoided. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 is a process flow chart of the present invention;

[0031] Figure 2 This is an explosion diagram of the hot pressing curing of the present invention.

[0032] Figures 1 to 2 The accompanying drawings are marked as follows: 1. base; 2. side wall; 3. female mold forming tool; 4. rubber material. DETAILED DESCRIPTION

[0033] like Figures 1 to 2 As shown, the method for manufacturing an integrally formed deep box-shaped part comprises the following steps:

[0034] S1. Extract the part's outer surface and prefabricate the female mold forming tooling;

[0035] The actual dimensions of the deep box-shaped parts are extracted, and metal female mold tooling is prefabricated. The combination of the metal female mold tooling is designed as a petal-type female mold tooling, which facilitates the subsequent demolding of the parts after the parts are processed. The Fibersim software is used to design the layup of the deep box-shaped parts and establish a layup plan, in which the parts at least include a base plate and peripheral side panels.

[0036] S2. Laying a predetermined amount of prepreg into the metal female mold according to the layup plan. A maximum of three prepreg layers are laid. In this embodiment, two prepreg layers are laid. During the prepreg laying process, the fibers of the base plate and the periphery layers are continuous in the R-corner area of ​​the female mold base plate, and the periphery layer splicing area avoids the R-corner area of ​​the periphery layer, thereby forming a layup.

[0037] Alternatively, you can use Fibersim software to design the layup layer for deep box-shaped parts, and make cuts in the prepreg in advance so that the prepreg splicing avoids the R corner during the laying process, so that the prepreg in the R corner area is limited and forms a continuous layup layer;

[0038] After the prepreg is laid, a soft silicone bead that matches the size of the R corner is placed in the R corner area of ​​the female mold. The preform made of the soft silicone bead in the shape of the R corner area can be used to fill the R corner. When filling the R corner, the soft silicone bead is pressed by a scraper to achieve a close fit with the R corner, ensuring that it is filled to a gapless state, avoiding bridging of the layers in the R corner area of ​​the metal female mold tooling and incomplete discharge of the prepreg gaps; after the soft silicone bead is pressed, the prepreg and the soft silicone bead are vacuum pre-compacted, wherein the vacuum pre-compaction pressure is 70kpa-90kpa and pre-pumped for 5-8 minutes to obtain a laying layer;

[0039] S3. After the vacuum pre-compacting treatment of the paving layer is completed to form a paving layer, the surface fiber flatness of the paving layer is inspected;

[0040] When the surface fibers of the paving layer are uneven, i.e., bulges or bridges appear, the uneven paving layer needs to be scraped and pressed to flatten the uneven parts to obtain a paving layer with smooth surface fibers, waiting for further processing.

[0041] When the surface fibers of the laying layer are flat, prepreg is laid on the laying layer to form a laying layer, and then the laying layer is vacuum pre-compacted to form a laying layer. The above inspection is repeated until all prepregs in the laying plan are laid to form a deep box part of a predetermined shape.

[0042] When external load acts on prepreg, stress will be transmitted along the surface of prepreg. At the R corner, due to the change of surface curvature, stress will be concentrated at the R corner, resulting in a larger stress value. If the splicing during paving is concentrated at the R corner, it will cause R corner fiber discontinuity, thereby reducing the strength and durability of carbon fiber materials, and causing the material to rupture or deform. Straight lines or smooth curves should be selected for splicing as much as possible to avoid sharp angles or corners.

[0043] S4. After the deep box part is formed, the groove of the deep box part is filled with rubber material. After the rubber material is placed, it is pressed to fully fill the groove, and the rubber material is scraped to make the rubber material flush with the opening of the groove. After compaction, it is packaged in a vacuum bag to obtain the part to be cured, and the part to be cured is hot-pressed and cured in an autoclave. During the hot-pressing and curing process, the rubber material may expand due to the tank pressure. In order to balance the pressure on the part to be cured, the vacuum bag is packaged in an envelope-type vacuum bag. The contact position between the vacuum bag and the rubber material has at least one group of folds, and the expansion space of the folds is larger than the expansion space of the rubber material. When the curing tank is hot-pressing and curing the part to be cured, the pressure of the expanded rubber material is used to press the deep box part. Parts are extruded. When the expansion pressure of the rubber material is less than the tank pressure, the pressure transmitted to the deep box-shaped parts is the tank pressure. When the expansion pressure of the rubber material is greater than the tank pressure, the vacuum bag is squeezed and released by the rubber material to achieve pressure balance. The pressure transmitted to the deep box-shaped parts is still the tank pressure. The negative membrane groove cavity is filled with rubber material, and the rubber material is vacuum-sealed with a vacuum bag. The whole is hot-pressed and cured. With the cooperation of the rubber material and the vacuum bag, the pressure of the deep box-shaped parts is ensured to be transmitted in place during the hot-pressing and curing process. At the same time, the risk of overpressure during the curing process of the product due to excessive expansion of the rubber clay can be avoided. After the hot-pressing and curing process of the parts to be cured is completed, the deep box-shaped parts are obtained. Only one set of metal negative mold forming tooling is required in combination with the rubber material to complete the entire laying and hot-pressing and curing molding, effectively controlling the tooling cost.

[0044] Through the above-mentioned manufacturing method, the present invention can produce the following parts:

[0045] like Figure 2 As shown, an integrally formed deep box-shaped part includes a base and side walls extending upward along the base; wherein the connection between the base and the side walls in the R-angle area is in the form of continuous fibers, and the side walls in the R-angle area are continuous prepreg, that is, the splicing joint of the prepreg of the side walls is outside the R-angle area, the side walls are integrally formed with the base, and the side walls are integrally connected to each other with a predetermined curvature, and the side walls and the base form a hollow structure with an open top.

[0046] The preferred embodiments of the present invention are described in detail above. However, the present invention is not limited to the specific details in the above embodiments. Within the technical concept of the present invention, various equivalent transformations can be made to the technical solutions of the present invention, and these equivalent transformations all fall within the scope of protection of the present invention.

Claims

1. A method for manufacturing an integrally formed deep box-shaped part, characterized in that: The following steps are involved: Step 1: Extract the part's outer surface and prefabricate the female mold forming tooling. The specific process is as follows: Step 1.1: Extract the shape of the part to be manufactured and prefabricate a metal female mold tooling. The metal female mold tooling is a split-flap modular tooling. The part includes at least a bottom plate and a peripheral side plate. Step 1.2: Use Fibersim software to design the paving layer for the deep box-shaped part, designing the base plate and perimeter of the part into a petal structure; Step 2: Lay out a predetermined amount of prepreg. After the prepreg is laid out, place a soft silicone strip that matches the R angle size in the R angle area of ​​the female mold. After the soft silicone strip is placed, use a tool to press the soft silicone strip until it is completely attached to the R angle. Then, vacuum pre-compact the prepreg and the soft silicone strip to obtain a laying layer. The specific process is as follows: Step 2.1, laying up to three layers of prepreg into the female mold tooling to form a laying layer; Step 2.2: Pre-pump the prepreg laid in step 2.1 at a pressure of 70kPa-90kPa for 5-8 minutes; Step 2.3: In step 2.1, fill the R corner area inside the female mold with soft silicone beading, and press the placed soft silicone beading to make it fit tightly with the R corner; Step 3: After the vacuum pre-compacting treatment in step 2 is completed, a paving layer is formed, and the surface fiber flatness of the paving layer is checked. If the surface fiber of the paving layer is flat, it is ready for further processing. If the surface fiber of the paving layer is uneven, the uneven paving layer needs to be scraped and pressed to flatten the uneven parts to obtain a paving layer with a flat surface fiber, which is ready for further processing. Step 4: Repeat steps 2 and 3 until all the paving layers are completed to obtain a deep box part of a predetermined shape; Step 5: Fill the groove of the deep box part in step 4 with rubber material. After placing the rubber material, press it to fully fill the groove, and scrape the rubber material so that the rubber material is flush with the groove opening. After compacting it and packaging it with a vacuum bag, the part to be cured is obtained. Then, the part to be cured is hot-pressed and cured to obtain a deep box-shaped part.

2. The method for manufacturing an integrally formed deep box-shaped part according to claim 1, characterized in that: Step 2.1, the process of laying prepreg is as follows: Step 2.11: The fibers of the base plate and the periphery are continuous in the R corner area of ​​the female mold base plate; Step 2.12, the ply splicing area of ​​the periphery avoids the periphery R corner area; during the laying process, first fix the prepreg to the base plate surface, and scrape and press the prepreg to lay it on the base plate surface and the base plate R corner. Then, scrape and press the periphery along the prepreg fiber direction from the base plate R corner to the periphery surface. When wrinkles appear in the periphery laying, cut the prepreg at the periphery along the fiber direction and lay it together. The cutting joint avoids the periphery R corner. At this time, the fibers of the prepreg at the R corner are in a continuous state; ensure the continuity of the fibers at the periphery R corner.

3. The method for manufacturing an integrally formed deep box-shaped part according to claim 1, wherein: Step 2.1, the process of laying prepreg is as follows: Step 2.11: Use Fibersim software to design the paving layers for the deep box-shaped parts. Make cuts in the prepreg in the cutting diagram so that the prepreg splicing avoids the R corners during the paving process.

4. The method for manufacturing an integrally formed deep box-shaped part according to claim 1, wherein: Step 5: vacuum bag packaging. The specific process is as follows: The vacuum bag packaging described in step 5.1 adopts envelope-type vacuum bag packaging.

5. The method for manufacturing an integrally formed deep box-shaped part according to claim 4, characterized in that: Step 5: vacuum bag packaging. The specific process is as follows: Step 5.2: The vacuum bag has at least one set of wrinkles at the contact position with the rubber material, and the expansion space of the wrinkles is larger than the expansion space of the rubber material; Step 5.3: The expansion pressure of the rubber material squeezes the deep box-shaped part. When the expansion pressure of the rubber material is less than the tank pressure, the pressure transmitted to the deep box-shaped part is the tank pressure. When the expansion pressure of the rubber material is greater than the tank pressure, the pressure is released by squeezing the vacuum bag through the rubber material to achieve pressure balance, and the pressure transmitted to the deep box-shaped part is still the tank pressure.

6. An integrally formed deep box-shaped part, characterized in that: It is made by the manufacturing method described in any one of claims 1-5, and includes a base, and a side wall extending upward along the base; the side wall is integrally formed with the base, and the side walls are integrally connected to each other with a predetermined curvature, and the side wall and the base form a hollow structure with an open top.

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