Soft tool forming method for accurate positioning of complex curved surface of resin-based carbon fiber composite material part

Abstract

The invention discloses a soft tool forming method for accurate positioning of a complex curved surface of a resin-based carbon fiber composite material part, which comprises the following steps of: performing digital-analog segmented blanking and paving of a reinforcing material on the resin-based carbon fiber composite material part with the complex curved surface to prepare a soft tool, drilling a plurality of blind holes in the surface of the soft tool through machining, and forming a plurality of holes in the surface of the soft tool. The flexible tool is matched with laser projection for precise positioning, so that the matching reference of the flexible tool and the resin-based carbon fiber composite material part before and after positioning is unified, the problem that the flexible tool is prone to positioning deviation is solved, and it is ensured that the position of the flexible tool is fixed and does not deviate in the forming process of the resin-based carbon fiber composite material part; therefore, the surface forming quality, the position precision and the internal quality of the resin-based carbon fiber composite material part are guaranteed, the qualified rate of production of the resin-based carbon fiber composite material part can be effectively improved, and the production efficiency is improved.

Description

Technical Field

[0001] The invention belongs to the technical field of composite material part molding, and in particular relates to a soft tooling molding method for precisely positioning a complex curved surface of a resin-based carbon fiber composite material part. Background Art

[0002] Resin-based carbon fiber composite materials have superior properties such as high specific strength, high specific stiffness, strong designability, good fatigue fracture resistance, corrosion resistance, and good dimensional stability. They are high-performance structural materials that are widely used in aviation, aerospace, transportation and other fields. Among the various carbon fiber composite molding processes, the autoclave process has uniform molding temperature and pressure, and has good adaptability to parts of different materials, shapes, sizes and structures. Therefore, it has become one of the main process methods for researching and manufacturing high-quality composite components for aerospace.

[0003] Resin-based carbon fiber composite parts with complex surfaces have very precise requirements for their shape contours after molding and their position on the parts. In the current autoclave process, rubber soft tooling is often used to assist in the molding of such parts. The advantage of using soft tooling is that on the one hand, soft tooling can improve the smoothness and flatness of the surface of resin-based carbon fiber composite parts, and at the same time, soft tooling can evenly conduct external pressure and heat to ensure the quality of resin-based carbon fiber composite parts after molding.

[0004] Soft tooling is generally made of rubber as the main material, with poor overall rigidity and cannot be mechanically positioned with the molding tooling. Therefore, during the molding process of resin-based carbon fiber composite parts, soft tooling is prone to positioning deviations, affecting the surface quality and internal lossless quality of the resin-based carbon fiber composite parts after molding. In severe cases, it may cause the parts to be scrapped. For this reason, we propose a soft tooling molding method for precise positioning of complex surfaces of resin-based carbon fiber composite parts. Summary of the invention

[0005] The purpose of the present invention is to provide a soft tooling molding method for accurately positioning the complex curved surface of a resin-based carbon fiber composite material part, so as to solve the problems raised in the above background technology.

[0006] To achieve the above object, the present invention provides the following technical solution: a soft tooling forming method for precisely positioning complex curved surfaces of resin-based carbon fiber composite parts, comprising the following steps: A. Soft tooling design: The digital model of the resin-based carbon fiber composite material part with complex curved surfaces is divided into several sections according to the changes in the curved surfaces, and the cutting diagram of the soft tooling reinforcement material is fitted and exported through simulation; B. Paving reinforcement materials: According to the exported soft tooling reinforcement material cutting diagram, rubber and reinforcement materials are laid on the molding tooling, and rubber strips are placed at the joints of the reinforcement materials to compensate. After laying, the molding tooling is packaged and then placed in an oven for hot compaction; C. Pressurized curing: The hot-compacted rubber and reinforcing material are fed into the autoclave together with the molding tooling, and are cured and molded under the curing conditions of the reinforcing material; D. Surface treatment: After the solidified soft tooling is cooled, it is sent to a five-axis CNC machine tool to drill blind holes before demoulding, and then the positioning is checked with the laser projection. After the verification is correct, the molded tooling and the solidified soft tooling are demoulded to obtain the soft tooling; E. Positioning: After demoulding, the soft tooling is laid with demoulding cloth on the surface of the resin-based carbon fiber composite material part, and the blind hole position is punched by laser projection to locate and adapt to the surface of the resin-based carbon fiber composite material part. After the package is pre-pressed, the positioning state of the soft tooling is determined by knocking, and the molding of the soft tooling is completed.

[0007] Preferably, in step A, the digital model of the resin-based carbon fiber composite material part with complex curved surfaces is divided into several sections according to the changes in the curved surfaces, that is, the area where the profile changes greatly in the digital model of the resin-based carbon fiber composite material part are divided into several sections according to the changes in the curved surfaces, and after segmentation, the blanking drawing is derived through Fibersim simulation.

[0008] Preferably, in step B, the forming tool is a Q235 steel metal forming tool.

[0009] Preferably, in step B, the rubber is made of PAD rubber, and the reinforcing material is glass fiber fabric prepreg or carbon fiber fabric prepreg.

[0010] Preferably, in step B, when the reinforcing material is laid, half of the reinforcing material is laid whole and the other half is spliced ​​in the area where the profile changes greatly.

[0011] Preferably, in step B, the number of layers of rubber and reinforcing material laid is determined according to the size and complexity of the resin-based carbon fiber composite material part.

[0012] Preferably, in step B, the number of rubber paving layers is 2-3, and the thickness of a single layer is 1-2 mm; the number of reinforcing material paving layers is 2-5, and the thickness of a single layer is 0.1-0.3 mm.

[0013] Preferably, in step B, the hot pressing conditions in the oven are: vacuum -90 kPa to -98 kPa, the hot pressing temperature is 1 / 3 of the curing temperature, and the hot pressing time is 55-65 min.

[0014] Preferably, in step D, the depth of the blind hole is greater than half of the thickness of the soft tooling, the diameter of the blind hole is 6-6.5 mm, and the number of blind holes is determined according to the size and complexity of the resin-based carbon fiber composite material part.

[0015] Preferably, in step E, the laser projection positioning blind holes is performed in a sequence from close projection to far projection, and from complex curved surface to smooth curved surface.

[0016] Compared with the prior art, the present invention has the following beneficial effects: 1. Compared with the traditional soft tooling molding method, the soft tooling of the present invention can evenly and accurately transfer the pressure applied by the autoclave to the surface of the resin-based carbon fiber composite material parts with complex curved surfaces, preventing thickness and losslessness problems; 2. The wall thickness of the soft tooling of the present invention is relatively thin, which can avoid the thermal hysteresis effect, effectively ensure the molding quality of resin-based carbon fiber composite material parts, and improve the qualified rate and efficiency of production; 3. Due to the presence of the carbon fiber or glass fiber reinforcement layer, the soft tooling of the present invention has a certain rigidity and shaping ability, which ensures the surface and dimensional accuracy of the resin-based carbon fiber composite material parts after molding. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a schematic diagram of positioning of the soft tooling of the present invention; Figure 2 It is a schematic diagram of the splicing position of the reinforcing material of the present invention; Figure 3 It is a schematic diagram of the soft tooling structure of the present invention.

[0018] In the figure: 1. Blind hole; 2. Soft tooling; 3. Area with large surface changes; 4. Laser projection; 5. Reinforcement material seams; 6. Rubber; 7. Reinforcement material; 8. Rubber strip. DETAILED DESCRIPTION

[0019] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0020] See also Figure 1-Figure 3 The soft tooling molding method for precisely positioning the complex curved surface of a resin-based carbon fiber composite material part provided by the present invention comprises the following steps: A. Soft tooling design: The digital model of the resin-based carbon fiber composite material part with complex curved surfaces is divided into several sections according to the changes in the curved surfaces, and the cutting diagram of the soft tooling reinforcement material is fitted and exported through simulation; In step A, the digital model of the resin-based carbon fiber composite material part with complex curved surfaces is divided into several sections according to the changes in the curved surfaces. The area where the profile of the digital model of the resin-based carbon fiber composite material part changes greatly is divided into several sections according to the changes in the curved surfaces. After the segmentation, the blanking drawing is derived through Fibersim simulation; B. Paving reinforcement materials: According to the derived soft tooling reinforcement material blanking diagram, rubber 6 and reinforcement material 7 are laid on the molding tooling, and rubber strips 8 are placed at the reinforcement material joints 5 to compensate. After laying, the molding tooling is packaged and then placed in an oven for hot compaction; In step B, the forming tool is a Q235 steel metal forming tool, and the soft tool is formed by the metal forming tool. A margin is left on both sides of the metal forming tool to facilitate packaging and feeding into the autoclave. The rubber is a PAD rubber material, and the reinforcing material is a glass fiber fabric prepreg or a carbon fiber fabric prepreg. When the reinforcing material is laid, the reinforcing material 7 is half laid and half spliced ​​in the area 3 where the profile changes greatly; In step B, the number of rubber and reinforcing material layers is determined according to the size and complexity of the resin-based carbon fiber composite material part. The number of rubber layers is 2-3, and the thickness of a single layer is 1-2 mm. The number of reinforcing material layers is 2-5, and the thickness of a single layer is 0.1-0.3 mm. In step B, the hot pressing conditions in the oven are: vacuum -90kPa to -98kPa, the hot pressing temperature is 1 / 3 of the curing temperature, and the hot pressing time is 55-65min; C. Pressurized curing: The hot-compacted rubber 6 and the reinforcing material 7 are fed into the autoclave together with the molding tool, and are cured and molded under the curing conditions of the reinforcing material 7; D. Surface treatment: After the solidified soft tooling 2 is cooled, it is sent to a five-axis CNC machine tool to drill a blind hole 1 before demoulding, and then the positioning is checked with a laser projection 4. After the verification is correct, the molding tool and the solidified soft tooling 2 are demoulded to obtain the soft tooling; In step D, the depth of blind hole 1 is greater than half of the thickness of the soft tooling, the diameter of the blind hole is 6-6.5 mm, and the number of blind holes is determined according to the size and complexity of the resin-based carbon fiber composite material part. E. Positioning: After demoulding, the soft tooling is laid with demoulding cloth on the surface of the resin-based carbon fiber composite material part, and the blind hole position is punched by laser projection to locate and adapt to the surface of the resin-based carbon fiber composite material part. After the package is pre-pressed, the positioning state of the soft tooling is determined by knocking, and the soft tooling is formed; In step E, the laser projection positioning blind holes is carried out in a sequence from close projection to far projection, and from complex curved surface to smooth curved surface.

[0021] The present invention prepares a soft tooling by cutting and laying reinforcing materials in sections on a resin-based carbon fiber composite material part with a complex curved surface through a digital model, and then drilling a plurality of blind holes on the surface of the soft tooling through machining, and performing precise positioning in conjunction with laser projection, so that the matching references of the soft tooling and the resin-based carbon fiber composite material part before and after positioning are unified, thereby solving the problem of positioning deviation of the soft tooling, ensuring that the position of the soft tooling is fixed without displacement during the molding process of the resin-based carbon fiber composite material part, thereby ensuring the surface molding quality, position accuracy and internal quality of the resin-based carbon fiber composite material part, and effectively improving the qualified rate of the production of the resin-based carbon fiber composite material part and improving the production efficiency; 1. Compared with the traditional soft tooling molding method, the soft tooling of the present invention can evenly and accurately transfer the pressure applied by the autoclave to the surface of the resin-based carbon fiber composite material parts with complex curved surfaces, preventing thickness and losslessness problems; 2. The wall thickness of the soft tooling of the present invention is relatively thin, which can avoid the thermal hysteresis effect, effectively ensure the molding quality of resin-based carbon fiber composite material parts, and improve the qualified rate and efficiency of production; 3. Due to the presence of the carbon fiber or glass fiber reinforcement layer, the soft tooling of the present invention has a certain rigidity and shaping ability, which ensures the surface and dimensional accuracy of the resin-based carbon fiber composite material parts after molding; Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A soft tooling molding method for precisely positioning complex curved surfaces of resin-based carbon fiber composite parts, characterized in that: The steps include: A. Soft tooling design: The digital model of the resin-based carbon fiber composite material part with complex curved surfaces is divided into several sections according to the changes in the curved surfaces, and the cutting diagram of the soft tooling reinforcement material is fitted and exported through simulation; B. Paving reinforcement materials: According to the exported soft tooling reinforcement material cutting diagram, rubber and reinforcement materials are laid on the molding tooling, and rubber strips are placed at the joints of the reinforcement materials to compensate. After laying, the molding tooling is packaged and then placed in an oven for hot compaction; C. Pressurized curing: The hot-compacted rubber and reinforcing material are fed into the autoclave together with the molding tooling, and are cured and molded under the curing conditions of the reinforcing material; D. Surface treatment: After the solidified soft tooling is cooled, it is sent to a five-axis CNC machine tool to drill blind holes before demoulding, and then the positioning is checked with the laser projection. After the verification is correct, the molded tooling and the solidified soft tooling are demoulded to obtain the soft tooling; E. Positioning: After demoulding, the soft tooling is laid with demoulding cloth on the surface of the resin-based carbon fiber composite material part, and the blind hole position is punched by laser projection to locate and adapt to the surface of the resin-based carbon fiber composite material part. After the package is pre-pressed, the positioning state of the soft tooling is determined by knocking, and the molding of the soft tooling is completed.

2. The soft tooling molding method for precisely positioning the complex curved surface of a resin-based carbon fiber composite material part according to claim 1, characterized in that: In step A, the digital model of the resin-based carbon fiber composite material part with complex surfaces is divided into several sections according to the surface changes. The area where the surface changes greatly in the digital model of the resin-based carbon fiber composite material part are divided into several sections according to the surface changes. After segmentation, the blanking drawing is exported through Fibersim simulation.

3. The soft tooling molding method for precisely positioning the complex curved surface of a resin-based carbon fiber composite material part according to claim 1, characterized in that: In step B, the forming tool is a Q235 steel metal forming tool.

4. The soft tooling molding method for precisely positioning the complex curved surface of a resin-based carbon fiber composite material part according to claim 1, characterized in that: In step B, the rubber is made of PAD rubber, and the reinforcing material is glass fiber fabric prepreg or carbon fiber fabric prepreg.

5. The soft tooling molding method for precisely positioning the complex curved surface of a resin-based carbon fiber composite material part according to claim 2, characterized in that: In step B, when the reinforcing material is laid, half of the reinforcing material is laid whole and the other half is spliced ​​in the area where the profile changes greatly.

6. The soft tooling molding method for precisely positioning the complex curved surface of a resin-based carbon fiber composite material part according to claim 5, characterized in that: In step B, the number of layers of rubber and reinforcement material is determined according to the size and complexity of the resin-based carbon fiber composite part.

7. The soft tooling molding method for precisely positioning the complex curved surface of a resin-based carbon fiber composite material part according to claim 6, characterized in that: In step B, the number of rubber paving layers is 2-3, and the thickness of a single layer is 1-2 mm. The number of reinforcing material paving layers is 2-5, and the thickness of a single layer is 0.1-0.3 mm.

8. The method for forming a soft tooling for precisely positioning a complex curved surface of a resin-based carbon fiber composite material part according to claim 1, characterized in that: In step B, the hot pressing conditions in the oven are: vacuum -90 kPa to -98 kPa, the hot pressing temperature is 1 / 3 of the curing temperature, and the hot pressing time is 55-65 min.

9. The method for forming a soft tooling for precisely positioning a complex curved surface of a resin-based carbon fiber composite material part according to claim 1, characterized in that: In step D, the depth of the blind hole is greater than half of the thickness of the soft tooling, the diameter of the blind hole is 6-6.5 mm, and the number of blind holes is determined according to the size and complexity of the resin-based carbon fiber composite material part.

10. The method for forming a soft tooling for precisely positioning a complex curved surface of a resin-based carbon fiber composite material part according to claim 1, characterized in that: In step E, the laser projection positioning blind holes is carried out in a sequence from close projection to far projection, and from complex curved surface to smooth curved surface.

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