Manufacturing method of hollow non-straight section composite material part

Abstract

The invention relates to the technical field of part manufacturing, in particular to a hollow non-straight section composite part which is characterized in that a low-melting-point alloy is used for manufacturing a core mold to serve as a forming inner mold, fiber prepreg is laid on the surface of the core mold and subjected to curing treatment to form a shell structure, finally, the inner mold is removed in a melting mode, and the hollow non-straight section composite part is obtained. According to the hollow non-straight composite material part manufacturing method, the characteristic that materials can be controllably removed is utilized, the mold design is greatly simplified, the manufacturing cost is reduced, and meanwhile the forming freedom degree of a complex geometric structure is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of parts manufacturing, and in particular to a method for manufacturing a hollow non-straight composite material part. Background Art

[0002] In the field of composite material forming and manufacturing technology, hollow non-straight parts (such as structural parts with features such as bends, variable cross-sections, and multiple curvatures) are in great demand in high-end fields such as aerospace and automotive industries due to their lightweight and high-strength characteristics. However, traditional rigid molds (metal cores, plaster molds, etc.) have problems such as large splicing errors, high demolding resistance, high costs, and difficulty adapting to complex curved surfaces. Soluble salt molds face low strength, limited demolding environment, and residual contamination risks. Low-melting-point plastic molds cause support failure because their melting temperature is lower than the curing temperature of composite materials. All of them cannot meet the molding needs of high-precision, complex geometric structures and efficient manufacturing requirements. With the lightweight upgrade of high-end equipment, the market has higher demands on the molding freedom, demolding reliability, and green and low-cost manufacturing of such parts.

[0003] Therefore, it is necessary to design a manufacturing method for hollow non-straight composite parts to solve the problems of low molding freedom, low demoulding reliability and high manufacturing cost of existing hollow non-straight composite parts. Summary of the Invention

[0004] In view of this, the present invention proposes a method for manufacturing hollow non-straight composite parts to solve the problems of low molding freedom, low demoulding reliability and high manufacturing cost of existing hollow non-straight composite parts.

[0005] The present invention proposes a method for manufacturing a hollow non-straight composite material part, comprising the following preparation steps:

[0006] According to the part model, a core mold model is reversely designed, and a core mold silicone mold is prepared according to the core mold model. The alloy material is heated to melt, and the melted alloy material is injected into the core mold silicone mold. After cooling, the mold is demoulded to obtain a core mold;

[0007] Pre-treating the core mold, laying prepreg layer by layer on the surface of the pre-treated core mold, installing positioning rings at both ends of the core mold to fix the prepreg, and obtaining a core mold wrapped with prepreg;

[0008] Wrapping the prepreg-wrapped core mold with a vacuum bag film, performing vacuum treatment, and then hot pressing and curing to obtain a cured prepreg-wrapped core mold;

[0009] The core mold wrapped with the solidified prepreg is heated, and the core mold is melted and flows out to obtain a rough part. The rough part is post-processed to obtain the hollow non-straight composite material part.

[0010] Furthermore, the melting point of the alloy material is 160-180°C.

[0011] Furthermore, when the alloy material is heated to melt, the heating temperature is 190° C.-210° C., and the alloy material is heated to melt and then kept warm for 20-40 minutes.

[0012] Furthermore, the pre-treatment is specifically as follows: ultrasonically clean the core mold for 5-15 minutes, sandblast the core mold for 10-30 seconds, apply a release agent on the surface of the core mold, dry it at 70°C for 30-50 minutes, and then cool it to room temperature.

[0013] Furthermore, before the prepreg is laid layer by layer on the pre-treated surface of the core mold, the prepreg is heated to 50-70°C, and the curved section of the core mold is locally heated to 50-70°C.

[0014] Furthermore, the vacuum treatment is specifically as follows: vacuuming to -0.098 MPa and maintaining the pressure for 30 minutes.

[0015] Furthermore, the hot pressing curing is specifically as follows: the temperature of the core mold wrapped with the prepreg is increased to 60°C at a heating rate of 5°C / min, kept warm for 30 minutes, and then the temperature of the core mold wrapped with the prepreg is increased to 130°C at a heating rate of 3°C / min and then pressurized to 0.8MPa, kept warm for 240 minutes, and then the temperature is reduced to 60°C at a cooling rate of 3°C / min and then naturally cooled to room temperature.

[0016] Furthermore, when the core mold wrapped with the cured prepreg is heated: the core mold wrapped with the cured prepreg is heated to 100°C at a heating rate of 5°C / min, kept warm for 60 minutes, and then the temperature is increased to 190°C-210°C at a heating rate of 5°C / min, and kept warm for 90 minutes.

[0017] Furthermore, when the core mold wrapped with the cured prepreg is heated, the outer wall of the core mold wrapped with the cured prepreg is tapped every 10 minutes.

[0018] Furthermore, the post-processing is specifically as follows: using 0.7 MPa compressed air to purge the rough parts for 5 min / hole, and then ultrasonically cleaning the rough parts for 20 minutes using 50° C. water at a frequency of 60 kHz.

[0019] Compared with the prior art, the beneficial effects of the present invention are: the present application uses a low-melting-point alloy to manufacture a core mold as an inner molding mold, forms an outer shell structure by laying fiber prepreg on its surface and performing a curing treatment, and finally removes the inner mold by melting, thereby obtaining a hollow non-straight composite material part with complete structure and accurate size. The present invention utilizes the characteristics of controllable material removal to greatly simplify mold design, reduce manufacturing costs, and at the same time improve the molding freedom of complex geometric structures. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Various other advantages and benefits will become apparent to those skilled in the art upon reading the detailed description of the preferred embodiment below. The accompanying drawings are for illustration purposes only and are not to be considered as limiting the present invention. The same reference symbols are used throughout the drawings to represent the same components. In the drawings:

[0021] Figure 1 This is a flow chart of a method for manufacturing a hollow non-straight composite material part provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0022] Exemplary embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. Although exemplary embodiments of the present disclosure are shown in the accompanying drawings, it should be understood that the present disclosure can be implemented in various forms and should not be limited by the embodiments set forth herein. On the contrary, these embodiments are provided to enable a more thorough understanding of the present disclosure and to fully convey the scope of the present disclosure to those skilled in the art. It should be noted that, unless there is a conflict, the embodiments of the present disclosure and the features in the embodiments can be combined with each other. The present invention will be described in detail below with reference to the accompanying drawings and in conjunction with the embodiments.

[0023] like Figure 1 As shown, in some embodiments of the present application, a method for manufacturing a hollow non-straight composite material part includes the following preparation steps:

[0024] According to the part model, a core mold model is reversely designed, and a core mold silicone mold is prepared according to the core mold model. The alloy material is heated to melt, and the melted alloy material is injected into the core mold silicone mold. After cooling, the mold is demoulded to obtain a core mold;

[0025] Pre-treating the core mold, laying prepreg layer by layer on the surface of the pre-treated core mold, installing positioning rings at both ends of the core mold to fix the prepreg, and obtaining a core mold wrapped with prepreg;

[0026] Wrapping the prepreg-wrapped core mold with a vacuum bag film, performing vacuum treatment, and then hot pressing and curing to obtain a cured prepreg-wrapped core mold;

[0027] The core mold wrapped with the solidified prepreg is heated, and the core mold is melted and flows out to obtain a rough part. The rough part is post-processed to obtain the hollow non-straight composite material part.

[0028] Specifically, CATIAV5R26 is used when designing the core mold model. The core mold is reverse designed based on the part CAD model. The inner cavity size needs to be enlarged to compensate for the shrinkage of the composite material during curing. For example, for a 100mm long part, the epoxy resin shrinkage during curing is calculated to be 0.3%, and the core mold design length is 100.3mm.

[0029] Specifically, when designing the core mold model, segmented curvature fitting is performed on the non-straight curved area (such as the R100mm arc segment), and a cross-section point is taken every 10mm to ensure that the surface continuity error is ≤0.02mm.

[0030] Specifically, the core mold silicone mold is prepared by 3D printing, and a 5% dimethyl silicone oil dilution liquid is sprayed on its inner wall. After preheating it to 50°C, the melted alloy material is injected into it. When the melted alloy material is injected into the core mold silicone mold, the mold is first placed in a vacuum box (vacuum degree -0.09MPa), and the alloy melt is injected into the mold through a guide tube. It is cooled to room temperature at a controlled cooling rate of 2°C / min, and then left to stand for 8 hours before demolding.

[0031] Specifically, when the prepreg is laid layer by layer on the surface of the core mold after pretreatment, the number of layers is preferably 8, of which the 1st, 3rd and 5th layers are laid along the axis of the part to bear the axial load; the 2nd, 4th and 6th layers are laid alternately along the ±45° direction of the axis to resist shear stress; the 7th and 8th layers are laid circumferentially along the 90° direction of the axis to enhance radial stiffness.

[0032] It can be understood that the present application uses a low-melting-point alloy to manufacture a core mold as an inner molding mold, forms an outer shell structure by laying fiber prepreg on its surface and performing a curing treatment, and finally removes the inner mold by melting, thereby obtaining a hollow non-straight composite material part with complete structure and accurate size. The present invention utilizes the characteristics of controllable material removal to greatly simplify the mold design, reduce manufacturing costs, and at the same time improve the molding freedom of complex geometric structures.

[0033] In some embodiments of the present application, the melting point of the alloy material is 160-180° C.; the melting point is preferably 170° C., and the alloy is preferably a lead-tin-bismuth ternary alloy.

[0034] It is understandable that the melting point of the alloy can be adjusted by adjusting the ratio of bismuth, tin and lead elements in the lead-tin-bismuth ternary alloy.

[0035] It is understandable that the melting point of the alloy is designed to be 160-180°C. This temperature range is higher than the mainstream curing temperature of epoxy resin-based prepregs (120-160°C), ensuring that the core mold remains solid during the curing process to provide stable support (compressive strength ≥30MPa) and avoid deformation of parts due to softening; it can also be quickly raised to above the melting point through external heating (such as a hot water bath, infrared radiation) after curing, and the molten liquid fluidity of the alloy is used to achieve stress-free demolding, avoiding damage to thin-walled structures (wall thickness ≤2mm) caused by the mechanical demolding force of traditional rigid molds. In addition, this temperature range is lower than the glass transition temperature of most composite materials (Tg ≥180°C), which can prevent resin degradation or dimensional distortion of parts due to overheating during the demolding process. At the same time, the molten alloy can be recycled and reused through condensation, with a material utilization rate exceeding 95%, significantly reducing mold costs.

[0036] In some embodiments of the present application, when the alloy material is heated to melt, the heating temperature is 190° C.-210° C., and the alloy material is heated to melt and then kept warm for 20-40 minutes.

[0037] Specifically, the heating temperature is determined by the melting point of the alloy material, and the heating temperature is the melting point of the alloy material + 30°C. For example, when the melting point of the alloy material is 160°C, the heating temperature is 190°C.

[0038] It is understandable that the main purpose of setting the heating temperature to the melting point of the alloy material + 30°C is to ensure that the core mold material is completely melted and has good fluidity.

[0039] In some embodiments of the present application, the pretreatment is specifically as follows: ultrasonically clean the core mold for 5-15 minutes, sandblast the core mold for 10-30 seconds, apply a release agent on the surface of the core mold, dry it at 70°C for 30-50 minutes, and then cool it to room temperature; the roughening treatment time is preferably 20 minutes, and the drying time is preferably 40 minutes.

[0040] Specifically, 80-mesh aluminum oxide sand (particle size 0.18 mm) was used in the sandblasting process, the sandblasting pressure was 0.4 MPa, and the blasting distance was 100 mm.

[0041] It is understandable that the surface micro-rough structure is constructed by mechanical grinding to optimize the interface characteristics between the core mold and the composite prepreg: on the one hand, sandblasting can completely remove the submicron-level contaminants (such as metal oxide film and release agent residue) remaining after ultrasonic cleaning, and form a rough texture of Ra6.3-12.5μm on the surface of the core mold. This roughness can prevent slippage and dislocation caused by the smooth surface during prepreg laying (the friction coefficient is increased by 40%-60%), and ensure the precise positioning of the fiber layer on complex curved surfaces; on the other hand, the controllable rough interface can form a "mechanical locking" effect during the curing process of the composite material, avoiding interlayer gaps caused by weak interface bonding force (porosity is reduced to less than 1%), and at the same time, through the micro-fracture characteristics of the rough peak, the interface peeling resistance can be reduced during demolding (especially in the molten alloy flow stage), so that the interface bonding strength between the core mold and the composite material is controlled within the range of 0.5-1.0MPa, which not only ensures the molding accuracy but also avoids the tearing of parts during demolding. In addition, the concave and convex structure formed by sandblasting can guide the molten alloy to flow evenly during the demolding process, preventing core mold residue caused by local retention. Combined with the subsequent drainage design, more than 99% of the core mold material can be recovered.

[0042] In some embodiments of the present application, before the prepreg is laid layer by layer on the surface of the pre-treated core mold, the prepreg is heated to 50-70°C, and the bending section of the core mold is locally heated to 50-70°C; the heating temperature of the prepreg is preferably 60°C; the local heating temperature of the bending section of the core mold is preferably 60°C.

[0043] Specifically, the prepreg is preferably a carbon fiber / epoxy resin prepreg (fiber volume fraction 60%-65%).

[0044] Specifically, after the prepreg is attached to the surface of the core mold, a rubber roller is used to roll and compact it along the curvature direction, with an interval of 10 minutes between each pass, for a total of 3 passes.

[0045] It can be understood that heating the prepreg can reduce the resin matrix viscosity of the epoxy resin-based prepreg to 1000-2000cP (70%-80% lower than room temperature), significantly improving the plastic deformation ability of the prepreg, so that it can fit closely to the complex curved surface of the core mold when laying the layers in the curved section (curvature radius ≤ 10mm), avoiding defects such as wrinkles and bridging caused by the rigidity of the material at room temperature; at the same time, local heating of the core mold can form a temperature gradient field, which promotes the contact interface between the prepreg and the core mold surface to produce mild physical cross-linking (molecular chain segment diffusion depth of 1-2μm), and control the initial bonding strength of the interface to 0.2-0.5MPa while ensuring the positioning accuracy of the layer, which prevents the layer from slipping and avoids excessive interface bonding during subsequent demolding. In addition, the heating state of 50-70℃ can inhibit the premature gelation of the prepreg, providing a 10-15 minute operating window for the precise laying of complex curved sections. Combined with the rough structure (Ra6.3-12.5μm) formed by sandblasting on the core mold surface, the porosity of the curved section ply can be controlled below 0.5%, and the fiber volume fraction can be increased to more than 65%, ultimately achieving high-precision molding and uniform mechanical properties of the curved section composite parts.

[0046] In some embodiments of the present application, the vacuum treatment is specifically: vacuuming to -0.098 MPa and maintaining the pressure for 30 minutes.

[0047] In some embodiments of the present application, the hot pressing curing is specifically as follows: the temperature of the core mold wrapped by the prepreg is increased to 60°C at a heating rate of 5°C / min, kept warm for 30 minutes, and then the temperature of the core mold wrapped by the prepreg is increased to 130°C at a heating rate of 3°C / min and then pressurized to 0.8MPa, kept warm for 240 minutes, and then the temperature is reduced to 60°C at a cooling rate of 3°C / min and then naturally cooled to room temperature.

[0048] It can be understood that the temperature is first raised to 60°C at 5°C / min and kept warm for 30 minutes to reduce the viscosity of the prepreg resin and expel the air between the layers. At the same time, the core mold remains solid to provide stable support, promotes light cross-linking of the resin to fix the position of the layers; then the temperature is raised to 130°C at 3°C / min and a pressure of 0.8MPa is applied for 240 minutes. The temperature is slowly raised to avoid thermal stress concentration. The high pressure causes the resin to fully infiltrate the fibers and compact the complex curved surface structure, ensuring that the resin is highly cross-linked (curing degree ≥95%) to form a high-strength cross-linked network; finally, the temperature is lowered to 60°C at 3°C / min and then cooled naturally. The thermal expansion difference between the composite material and the core mold is reduced by a controlled cooling rate, internal stress is released and microcracks are avoided, ensuring that the shape of the parts is fixed after cooling and the dimensional accuracy meets the standards

[0049] In some embodiments of the present application, when the core mold wrapped with the cured prepreg is heated: the core mold wrapped with the cured prepreg is heated to 100°C at a heating rate of 5°C / min, kept warm for 60 minutes, and then the temperature is increased to 190°C-210°C at a heating rate of 5°C / min, and kept warm for 90 minutes.

[0050] Specifically, the final heating temperature is determined by the melting point of the alloy material of the core mold, and the final heating temperature is the melting point of the alloy material of the core mold + 30°C.

[0051] It is understandable that this temperature can not only enable the alloy to break through the critical point of solid-liquid phase transition and form a low-viscosity liquid (surface tension reduced by 30%-40%), which is convenient for rapid drainage from complex inner cavities (such as curved sections, variable-section channels) under the action of gravity or slight external force, avoiding core mold residues caused by local unmelted; it can also control the temperature rise within the tolerance range of the composite material (20-30°C lower than its glass transition temperature) to prevent overheating from causing degradation of the resin matrix or damage to the fiber-resin interface. In addition, a superheat of 30°C can shorten the melting time to 30-60 minutes (increasing efficiency by 50% compared to when only the melting point is reached), while ensuring that the fluidity of the molten alloy meets the drainage requirements of the minimum pore size (2-5mm). Combined with the preset drainage hole design, lossless demolding of non-straight hollow structures and complete recovery of core mold materials (recovery rate ≥98%) can be achieved.

[0052] In some embodiments of the present application, when the core mold wrapped with the cured prepreg is heated, the outer wall of the core mold wrapped with the cured prepreg is tapped every 10 minutes.

[0053] It is understandable that tapping the outer wall of the core mold wrapped with the cured prepreg every 10 minutes can effectively promote the flow of the alloy and improve the demoulding efficiency.

[0054] In some embodiments of the present application, the post-processing is specifically: using 0.7MPa compressed air to purge the rough parts, the purge time is 5min / hole, and after completion, the rough parts are ultrasonically cleaned for 20 minutes using 50°C water at a frequency of 60kHz; the water is preferably deionized water.

[0055] Example 1

[0056] S1. Reverse-design a core mold model based on the part model, prepare a core mold silicone mold based on the core mold model by 3D printing technology, spray a 5% dimethyl silicone oil dilution solution on the inner wall of the core mold silicone mold, and preheat it to 50°C;

[0057] S2. A lead-tin-bismuth ternary alloy with a melting point of 160° C. is heated to 190° C. and melted, and the alloy is kept warm for 20 minutes. The silicone mold is then placed in a vacuum box with a vacuum degree of -0.09 MPa. The alloy melt is injected into the silicone mold through a flow guide tube, and the mold is cooled to room temperature at a controlled cooling rate of 2° C. / min. The mold is then demolded after standing for 8 hours to obtain the core mold.

[0058] S3. After ultrasonically cleaning the core mold for 5 minutes, the core mold was roughened for 10 seconds using 80-mesh alumina sand (particle size 0.18 mm), a sandblasting pressure of 0.4 MPa, and a spraying distance of 100 mm. A release agent was then applied to the surface of the core mold and dried at 70°C for 30 minutes. Afterwards, the mold was cooled to room temperature.

[0059] S4. Locally heat the bending section core mold to 50°C, and laminate the 50°C carbon fiber / epoxy resin prepreg to the surface of the core mold layer by layer. During the lamination, use a rubber roller to roll and compact each layer along the curvature direction. Each pass is 10 minutes apart, and a total of 3 passes are performed. After completion, positioning rings are installed at both ends of the core mold to fix the prepreg to obtain a prepreg-wrapped core mold.

[0060] S5. Wrap the prepreg-wrapped core mold with a vacuum bag film, then evacuate to -0.098 MPa, hold the pressure for 30 min, raise the temperature of the prepreg-wrapped core mold to 60 ° C at a heating rate of 5 ° C / min, keep warm for 30 minutes, then raise the temperature of the prepreg-wrapped core mold to 130 ° C at a heating rate of 3 ° C / min, pressurize 0.8 MPa, keep warm for 240 min, then reduce the temperature to 60 ° C at a cooling rate of 3 ° C / min and naturally cool to room temperature to obtain a cured prepreg-wrapped core mold;

[0061] S6. Heat the core mold wrapped with the cured prepreg to 100°C at a heating rate of 5°C / min, keep it warm for 60 minutes, then increase the temperature to 190°C at a heating rate of 5°C / min, keep it warm for 90 minutes, and when the core mold melts and flows out, a rough part is obtained.

[0062] S7. Use 0.7 MPa compressed air to purge the rough parts for 5 min / hole. After completion, use 50°C deionized water at a frequency of 60 kHz to ultrasonically clean the rough parts for 20 minutes to obtain the hollow non-straight composite material parts.

[0063] Example 2

[0064] S1. Reverse-design a core mold model based on the part model, prepare a core mold silicone mold based on the core mold model by 3D printing technology, spray a 5% dimethyl silicone oil dilution solution on the inner wall of the core mold silicone mold, and preheat it to 50°C;

[0065] S2. A lead-tin-bismuth ternary alloy with a melting point of 170°C is heated to 190°C for melting and kept warm for 30 minutes. The silicone mold is then placed in a vacuum box with a vacuum degree of -0.09 MPa. The alloy melt is injected into the silicone mold through a guide tube, and the mold is cooled to room temperature at a controlled cooling rate of 2°C / min. The mold is then demoulded after standing for 8 hours to obtain the core mold.

[0066] S3. After ultrasonically cleaning the core mold for 10 minutes, the core mold was roughened for 20 seconds using 80-mesh alumina sand (particle size 0.18 mm), a sandblasting pressure of 0.4 MPa, and a sandblasting distance of 100 mm. A release agent was then applied to the surface of the core mold and dried at 70°C for 40 minutes. Afterwards, the mold was cooled to room temperature.

[0067] S4. Locally heat the bending section core mold to 60°C, and laminate the 60°C carbon fiber / epoxy resin prepreg to the surface of the core mold layer by layer. During the lamination, use a rubber roller to roll and compact each layer along the curvature direction. Each pass is 10 minutes apart, and a total of 3 passes are performed. After completion, positioning rings are installed at both ends of the core mold to fix the prepreg to obtain a prepreg-wrapped core mold.

[0068] S5. Wrap the prepreg-wrapped core mold with a vacuum bag film, then evacuate to -0.098 MPa, hold the pressure for 30 min, raise the temperature of the prepreg-wrapped core mold to 60 ° C at a heating rate of 5 ° C / min, keep warm for 30 minutes, then raise the temperature of the prepreg-wrapped core mold to 130 ° C at a heating rate of 3 ° C / min, pressurize 0.8 MPa, keep warm for 240 min, then reduce the temperature to 60 ° C at a cooling rate of 3 ° C / min and naturally cool to room temperature to obtain a cured prepreg-wrapped core mold;

[0069] S6. The core mold wrapped with the cured prepreg is heated to 100°C at a heating rate of 5°C / min and kept warm for 60 minutes. The temperature is then raised to 200°C at a heating rate of 5°C / min and kept warm for 90 minutes. When the core mold melts and flows out, a rough part is obtained.

[0070] S7. Use 0.7 MPa compressed air to purge the rough parts for 5 min / hole. After completion, use 50°C deionized water at a frequency of 60 kHz to ultrasonically clean the rough parts for 20 minutes to obtain the hollow non-straight composite material parts.

[0071] Example 3

[0072] S1. Reverse-design a core mold model based on the part model, prepare a core mold silicone mold based on the core mold model by 3D printing technology, spray a 5% dimethyl silicone oil dilution solution on the inner wall of the core mold silicone mold, and preheat it to 50°C;

[0073] S2. A lead-tin-bismuth ternary alloy with a melting point of 180° C. is heated to 190° C. and melted, and the alloy is kept warm for 40 minutes. The silicone mold is then placed in a vacuum box with a vacuum degree of -0.09 MPa. The alloy melt is injected into the silicone mold through a flow guide tube, and the mold is cooled to room temperature at a controlled cooling rate of 2° C. / min. The mold is then demolded after standing for 8 hours to obtain the core mold.

[0074] S3. After ultrasonically cleaning the core mold for 15 minutes, the core mold was roughened for 30 seconds using 80-mesh alumina sand (particle size 0.18 mm), a sandblasting pressure of 0.4 MPa, and a spraying distance of 100 mm. A release agent was then applied to the surface of the core mold and dried at 70°C for 50 minutes. Afterwards, the mold was cooled to room temperature.

[0075] S4. Locally heat the bending section core mold to 70°C, and laminate the 70°C carbon fiber / epoxy resin prepreg to the surface of the core mold layer by layer. During the lamination, use a rubber roller to roll and compact each layer along the curvature direction. Each pass is 10 minutes apart, and a total of 3 passes are performed. After completion, positioning rings are installed at both ends of the core mold to fix the prepreg to obtain a prepreg-wrapped core mold.

[0076] S5. Wrap the prepreg-wrapped core mold with a vacuum bag film, then evacuate to -0.098 MPa, hold the pressure for 30 min, raise the temperature of the prepreg-wrapped core mold to 60 ° C at a heating rate of 5 ° C / min, keep warm for 30 minutes, then raise the temperature of the prepreg-wrapped core mold to 130 ° C at a heating rate of 3 ° C / min, pressurize 0.8 MPa, keep warm for 240 min, then reduce the temperature to 60 ° C at a cooling rate of 3 ° C / min and naturally cool to room temperature to obtain a cured prepreg-wrapped core mold;

[0077] S6. Heat the core mold wrapped with the cured prepreg to 100°C at a heating rate of 5°C / min, keep it warm for 60 minutes, then increase the temperature to 210°C at a heating rate of 5°C / min, keep it warm for 90 minutes, and when the core mold melts and flows out, a rough part is obtained.

[0078] S7. Use 0.7 MPa compressed air to purge the rough parts for 5 min / hole. After completion, use 50°C deionized water at a frequency of 60 kHz to ultrasonically clean the rough parts for 20 minutes to obtain the hollow non-straight composite material parts.

[0079] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as within the scope of protection of the present invention.

Claims

1. A method for manufacturing a hollow non-straight composite material part, characterized in that: The method comprises the following preparation steps: According to the part model, a core mold model is reversely designed, and a core mold silicone mold is prepared according to the core mold model. The alloy material is heated to melt, and the melted alloy material is injected into the core mold silicone mold. After cooling, the mold is demoulded to obtain a core mold; Pre-treating the core mold, laying prepreg layer by layer on the surface of the pre-treated core mold, installing positioning rings at both ends of the core mold to fix the prepreg, and obtaining a prepreg-wrapped core mold; Wrapping the prepreg-wrapped core mold with a vacuum bag film, performing a vacuum treatment, and then hot pressing and curing to obtain a cured prepreg-wrapped core mold; The core mold wrapped with the solidified prepreg is heated, and the core mold is melted and flows out to obtain a rough part. The rough part is post-processed to obtain the hollow non-straight composite material part.

2. The method for manufacturing a hollow non-straight composite material part according to claim 1, characterized in that: The alloy material has a melting point of 160-180°C.

3. The method for manufacturing a hollow non-straight composite material part according to claim 2, characterized in that: When the alloy material is heated to melt, the heating temperature is 190° C.-210° C., and the alloy material is heated to melt and then kept warm for 20-40 minutes.

4. The method for manufacturing a hollow non-straight composite material part according to claim 3, characterized in that: The pretreatment specifically includes: ultrasonically cleaning the core mold for 5-15 minutes, sandblasting the core mold for 10-30 seconds, coating the surface of the core mold with a release agent, drying the core mold at 70° C. for 30-50 minutes, and then cooling the core mold to room temperature.

5. The method for manufacturing a hollow non-straight composite material part according to claim 4, characterized in that: Before laying the prepreg layer by layer on the pre-treated surface of the core mold, the prepreg is heated to 50-70°C, and the curved section of the core mold is locally heated to 50-70°C.

6. The method for manufacturing a hollow non-straight composite material part according to claim 5, characterized in that: The vacuum treatment is specifically as follows: vacuuming to -0.098 MPa and maintaining the pressure for 30 minutes.

7. The method for manufacturing a hollow non-straight composite material part according to claim 6, characterized in that: The hot pressing curing is specifically as follows: the temperature of the core mold wrapped with the prepreg is increased to 60°C at a heating rate of 5°C / min, kept warm for 30 minutes, then the temperature of the core mold wrapped with the prepreg is increased to 130°C at a heating rate of 3°C / min, pressurized to 0.8MPa, kept warm for 240 minutes, then the temperature is reduced to 60°C at a cooling rate of 3°C / min, and then naturally cooled to room temperature.

8. The method for manufacturing a hollow non-straight composite material part according to claim 7, characterized in that: When heating the core mold wrapped with the cured prepreg: heat the core mold wrapped with the cured prepreg to 100°C at a heating rate of 5°C / min, keep warm for 60 minutes, then increase the temperature to 190°C-210°C at a heating rate of 5°C / min, and keep warm for 90 minutes.

9. The method for manufacturing a hollow non-straight composite material part according to claim 8, characterized in that: When the core mold wrapped with the cured prepreg is heated, the outer wall of the core mold wrapped with the cured prepreg is tapped every 10 minutes.

10. The method for manufacturing a hollow non-straight composite material part according to claim 9, characterized in that: The post-treatment is specifically as follows: the rough parts are purged with 0.7 MPa compressed air for 5 min / hole, and then the rough parts are ultrasonically cleaned for 20 minutes with 50° C. water at a frequency of 60 kHz.

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