A composite molding die for improving the processing quality of resin-based composite materials

Abstract

The application discloses a composite forming die for improving processing quality of resin-based composite materials, which comprises a die top plate, a die bottom plate and a cutting screw, and preset threaded holes are arranged on the die top plate and the die bottom plate; the cutting screw comprises a screw body and a cutting part; the screw body comprises a hexagonal nut and a screw shaft connected with the hexagonal nut, and the screw shaft is provided with a first shaft shoulder and a second shaft shoulder; the cutting part comprises a cutting body and a connecting shaft, and the bottom of the cutting body is provided with a cutting edge; and the metal ring is arranged on the connecting shaft in the process that the cutting screw processes the composite material preform in a hole. The composite forming die of the application is matched with the metal ring, the metal ring is embedded into the composite material preform to form a metal ring hole in the process that the composite material preform is drilled, the generation of defects such as fiber misplacement and interlayer peeling can be avoided, the overall stability and strength of the preform are effectively enhanced, and the assembly precision and reliability of the preform are improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of composite materials and metal materials composite forming, in particular to a composite forming die for improving the processing quality of resin-based composite materials. BACKGROUND

[0002] Carbon fiber is a kind of advanced material with light weight and high strength, which has wide application prospects in the fields of aerospace, automobile industry, sports equipment, medical treatment, construction, etc. Drilling and assembling inside carbon fiber parts is a common manufacturing process, which can realize the fixed installation of additional parts, improve the overall performance and structural strength of the product, and meet the demand of lightweight and high strength in high-end industrial fields. However, carbon fiber parts often cause various defects during drilling process, which seriously affects the assembly accuracy and final performance. These defects mainly include the following four aspects: ① fiber misalignment and fracture: the directionality of carbon fiber is very important, but fiber misalignment or fracture phenomenon often occurs during processing, which reduces the fiber strength and stiffness, and affects the load capacity of the part. ② interlaminar delamination: in the multi-layer stacked carbon fiber composite material, due to the poor interlaminar bonding or excessive processing stress, interlaminar delamination phenomenon is easy to occur, which reduces the overall performance of the part. ③ cracks and bubbles: carbon fiber parts are also prone to cracks or bubbles during processing, which affects the surface quality and structural integrity, and further affects the assembly accuracy and reliability. ④ residual stress: the residual stress generated during processing may cause deformation or damage of carbon fiber parts, which further affects the assembly accuracy and stability.

[0003] In view of the above problems, scholars in the industry have carried out some related researches. For example, the patent for invention with the authorization announcement number CN109351999B discloses a drill bit with a groove cylinder, which is mainly used for processing high-hardness fiber reinforced ceramic matrix composite materials. However, using this drill bit to drill resin-based composite materials is easy to cause burr, thermal damage and poor processing surface quality, etc., which even affects the service life and performance stability of the composite material parts. For another example, the patent for invention with the application announcement number CN109927106A discloses a method for drilling composite materials using robots, which can improve the drilling positioning accuracy, but cannot effectively solve the problems of fiber misalignment and interlaminar delamination that are easy to occur during the drilling process of composite materials. SUMMARY

[0004] The present application aims to overcome the shortcomings of the prior art, and provides a composite forming die for improving the processing quality of resin-based composite materials, which introduces a metal ring hole in the composite material forming process, can effectively avoid various defects generated during the drilling process of composite material parts, and further ensure the quality and performance of the composite material parts, and realize more stable and reliable assembly effect.

[0005] In order to achieve the above object, the application provides a composite forming die for improving the processing quality of resin-based composite materials, which is used for composite forming processing of a composite material preform and a metal ring, and comprises a die top plate, a die bottom plate and a cutting screw, wherein preset threaded holes corresponding to to-be-holed parts of the composite material preform are formed on the die top plate and the die bottom plate; the cutting screw comprises a threaded screw body and a cutting part, the screw body comprises a hexagonal nut and a screw shaft connected with the hexagonal nut, a first shaft shoulder is arranged on the outer surface of one end of the screw shaft connected with the hexagonal nut, and a connecting recess is arranged on the end face of the other end of the screw shaft; the cutting part comprises a cutting body and a connecting shaft arranged on the cutting body, and a cutting edge for holed processing of the composite material preform is formed on the bottom of the cutting body; the connecting shaft is threadedly connected with the connecting recess; and in the process of holed processing of the composite material preform by the cutting screw to form a composite material part with a metal ring hole, the metal ring is sleeved on the connecting shaft.

[0006] Further, a second shaft shoulder is arranged on the outer surface of the other end of the screw shaft, and an annular recess is formed between the first shaft shoulder and the second shaft shoulder; the diameter of the second shaft shoulder is the same as the outer diameter of the metal ring; and the diameter of the first shaft shoulder is greater than the diameter of the second shaft shoulder.

[0007] Further, the sum of the thickness of the second shaft shoulder and the height of the annular recess is the same as the thickness of the die top plate; the thickness of the cutting body is the same as the thickness of the die bottom plate; and the height of the metal ring is the same as the thickness of the composite material preform.

[0008] Further, the second shaft shoulder and the cutting body are respectively provided with threads for cooperation with the preset threaded holes on the die top plate and the die bottom plate.

[0009] Further, a hexagonal recess is arranged on the bottom surface of the cutting body, which is recessed inward, and is used for unscrewing the cutting part and the screw body after solidification and forming.

[0010] Further, a forming recess with three side walls is arranged on the top surface of the die bottom plate, and clamping grooves are formed on two opposite side walls of the forming recess; and clamping edges matched with the clamping grooves are arranged on two opposite side surfaces of the die top plate.

[0011] Compared with the prior art, the application has the following beneficial effects:

[0012] The composite forming die of the present application comprises a die top plate, a die bottom plate and a cutting screw, the cutting screw comprising a screw body and a cutting part in threaded connection; the composite forming die of the present application is matched with a metal ring, in the process of drilling a hole in a composite material preform, the metal ring is embedded in the composite material preform to form a metal ring hole, which can avoid the generation of defects such as fiber misplacement and interlayer peeling, and effectively enhance the overall stability and strength of the preform, so as to improve the assembly precision and reliability of the preform.

[0013] In addition to the objects, features and advantages described above, the present application has other objects, features and advantages. The present application will be further described below with reference to the drawings. BRIEF DESCRIPTION OF DRAWINGS

[0014] The accompanying drawings are included to provide a further understanding of the embodiments of the present application, and constitute a part of the specification, and are used together with the following detailed description to explain the embodiments of the present application, but do not constitute a limitation on the embodiments of the present application. In the drawings:

[0015] Figure 1 is a structural schematic diagram of a composite forming die in the composite forming method of the present application;

[0016] Figure 2 is a structural schematic diagram of a die bottom plate in the composite forming method of the present application;

[0017] Figure 3 is a front view structural schematic diagram of the cooperation of the cutting screw and the metal ring in the composite forming method of the present application;

[0018] Figure 4 is a side view (exploded) structural schematic diagram of the cooperation of the cutting screw and the metal ring in the composite forming method of the present application;

[0019] In the drawings, 1 is a die bottom plate; 1.1 is a forming groove; 1.2 is a clamping groove; 2 is a die top plate; 2.1 is a clamping blade; 3 is a cutting screw; 3.1 is a hexagonal nut; 3.2 is a first shaft shoulder; 3.3 is an annular groove; 3.4 is a second shaft shoulder; 3.5 is a connecting groove; 3.6 is a cutting body; 3.6a is a cutting blade; 3.7 is a connecting shaft; 3.8 is a hexagonal groove; A is a composite material preform; B is a metal ring; C is a screw body; D is a cutting part, and a is a pre-set threaded hole. DETAILED DESCRIPTION

[0020] The present application will be described in detail below with reference to the embodiments shown in the drawings, but it should be noted that these embodiments are not a limitation on the present application, and equivalent transformations or substitutions of function, method or structure made by those skilled in the art based on these embodiments are within the protection scope of the present application.

[0021] AsFigures 1 to 4 As shown in the drawings, the embodiment provides a composite forming die for improving the processing quality of resin-based composite materials, which is used for composite forming processing of a composite material preform A and a metal ring B; the composite forming die comprises a die bottom plate 1, a die top plate 2 and a cutting screw 3, and the specific structure is as follows:

[0022] The die bottom plate 1 and the die top plate 2 are provided with preset threaded holes a corresponding to the to-be-drilled parts of the composite material preform A, and the positions and the number of the preset threaded holes a are set according to the drilling requirements of the composite material preform A to be processed. Figure 3 and Figure 4 As shown in the drawings, the cutting screw 3 comprises a threaded screw body C and a cutting part D, the screw body C comprises a hexagonal nut 3.1 and a screw shaft connected with the hexagonal nut 3.1, the outer surface of the end connected with the hexagonal nut 3.1 of the screw shaft is provided with a first shaft shoulder 3.2, the outer surface of the other end of the screw shaft is provided with a second shaft shoulder 3.4, and the space between the first shaft shoulder 3.2 and the second shaft shoulder 3.4 forms an annular groove 3.3. The height of the metal ring B is the same as the thickness of the composite material preform A, the diameter of the second shaft shoulder 3.4 is the same as the outer diameter of the metal ring B, and the diameter of the first shaft shoulder 3.2 is greater than the diameter of the second shaft shoulder 3.4. The sum of the thickness of the second shaft shoulder 3.4 and the height of the annular groove 3.3 is the same as the thickness of the die bottom plate 1. The end surface of the other end of the screw shaft is provided with an inwardly recessed connecting groove 3.5. The cutting part D comprises a cutting body 3.6 and a connecting shaft 3.7 arranged on the cutting body 3.6, and the bottom of the cutting body 3.6 is circumferentially provided with a cutting edge 3.6a for drilling the composite material preform A. In the process of drilling the composite material preform A, the metal ring B is sleeved on the connecting shaft 3.7. The thickness of the cutting body 3.6 is the same as the thickness of the die top plate 2. In the structure, the surfaces of the second shaft shoulder 3.4 and the cutting body 3.6 are respectively provided with external threads matched with the preset threaded holes a on the die top plate and the die bottom plate, the annular groove 3.3 is used for tool withdrawal when machining the external threads on the second shaft shoulder 3.4, and the connecting shaft 3.7 is threadedly connected with the connecting groove 3.5.

[0023] In the embodiment, the top surface of the die bottom plate 1 is provided with a forming groove 1.1 having three side walls, and the inner sides of two opposite side walls of the forming groove 1.1 are provided with clamping grooves 1.2. The two opposite side surfaces of the die top plate 2 are provided with clamping edges 2.1 matched with the clamping grooves 1.2. In use, the die top plate 2 is slid into the forming groove 1.1 through the side without the side wall, so as to be used for drilling positioning and compacting the composite material preform. The bottom surface of the cutting body 3.6 is further provided with an inwardly recessed hexagonal groove 3.8, so that the cutting part D and the screw body C can be loosened by using a wrench after solidification and forming, and then the cutting screw can be taken out from the composite material preform.

[0024] Embodiments

[0025] In this embodiment, the composite material preform A is made of carbon fiber reinforced resin matrix composite material prepreg, and the carbon fiber reinforced resin matrix composite material prepreg is T700 / TRE231. The prepreg is cut into 200x200mm (consistent with the size of the mold bottom plate) according to the preset size, the layer angle is [0 / 90 / 0 / 90 / 0 / 90 / 0 / 90 / 0 / 90]s, the single-layer thickness of the prepreg is 0.125mm, the overall thickness of the composite material preform A is 2.5mm, and the thickness of the metal ring is equal to the overall thickness of the composite material preform A; the height of the annular groove 3.3 and the thickness of the second shaft shoulder 3.4 are 1.25mm respectively, and the height of the connecting shaft 3.7 and the depth of the connecting groove 3.5 are 5mm and 2.5mm respectively. The surfaces of the mold bottom plate and the mold top plate in contact with the composite material preform A are sprayed with solvent-based release agent, then the above-mentioned composite material preform is placed in the forming groove of the mold bottom plate, so that the periphery of the preform is tightly attached to the periphery of the mold bottom plate, the thickness of the mold top plate is 2.5mm, the preset thread a hole diameter in the mold top plate and the mold bottom plate is M12, the clamping blade of the mold top plate is slid into the clamping groove to ensure that the open end surface of the mold top plate and the mold bottom plate (i.e. the end surface of one side of the forming groove 1.1 which is not provided with a side wall) is in the same plane. Then the metal ring is sleeved on the connecting shaft, and the connecting shaft and the connecting groove are locked; the cutting screw is screwed into the threaded hole of the mold top plate by using a hexagonal wrench, as the cutting screw penetrates deeper, the cutting edge removes the material in the punched part of the composite material preform, when the first shaft shoulder is tightly attached to the mold top plate, the metal ring has been embedded in the composite material preform at this moment, and the rotation of the cutting screw is stopped; the above-mentioned composite material preform and the composite forming mold are placed as a whole on an aluminum alloy flat mold with a size of 350x400mm, the air permeable felt and the vacuum bag are laid on the upper surface of the above-mentioned overall structure, the vacuum nozzle is embedded in the vacuum bag, and finally the vacuum bag tightness test is carried out. When the pressure is drawn to-100kPa, the vacuum pump is turned off, and after standing for 5min, the vacuum degree is-100kPa, the above-mentioned whole (vacuum package) is placed in a hot press tank, and the vacuum package is heated from room temperature to 129℃ at a rate of 1.5℃ / min; at the same time, the pressure is increased to 0.6MPa at a rate of 0.02Mpa / min, and the pressure is maintained for 125min. After the heat preservation and pressure holding is completed, the vacuum package is cooled to 60℃ at a rate of 1.3℃ / min; at the same time, the pressure is reduced to 0MPa at a rate of 0.02MPa / min, and the curing forming of the metal ring and the composite material preform is completed. After the vacuum bag is disassembled, the cutting part is loosened by an internal hexagonal wrench, the cutting screw is rotated out by an external hexagonal wrench, the mold top plate is slid to separate the clamping groove and the clamping blade, and the composite material part with a metal ring hole (i.e. a "metal+composite" part) is obtained. Finally, the metal ring on the obtained composite material part is processed to meet the machining precision requirements of the hole.

[0026] The embodiment provides a "metal+composite" part composite forming die, and high-precision and high-quality metal-embedded composite part forming can be realized. The composite forming die is used for composite forming processing of the metal ring and the composite material preform in cooperation, the metal ring is embedded into the composite material preform in a nested mode, the metal embedding can provide additional support and constraint, the layers of the composite material are tightly combined, and problems such as fiber misplacement and interlayer peeling can be effectively prevented; the metal ring hole is formed in the composite material, the deformation and cracks of the part can be reduced, and then the overall stability and strength of the part are enhanced.

[0027] The above merely describes the preferred embodiments of the present application and is not used to limit the present application. For those skilled in the art, the present application can have various modifications and changes. Any modification, equivalent replacement, improvement, etc. within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A composite molding mold for improving the processing quality of a resin-based composite material, characterized by, The composite forming die is used for composite forming processing of a composite material preform (A) and a metal ring (B), and comprises a die top plate (2), a die bottom plate (1) and a cutting screw (3). The die top plate (2) and the die bottom plate (1) are provided with preset threaded holes (a) corresponding to the to-be-drilled parts of the composite material preform (A). The cutting screw (3) comprises a threaded screw body (C) and a cutting part (D). The screw body (C) comprises a hexagonal nut (3.1) and a screw shaft connected with the hexagonal nut (3.1). A first shaft shoulder (3.2) is arranged on the outer surface of the end connected with the hexagonal nut (3.1) of the screw shaft. A connecting recess (3.5) is arranged on the end face of the other end of the screw shaft. The cutting part (D) comprises a cutting body (3.6) and a connecting shaft (3.7) arranged on the cutting body (3.6). The bottom of the cutting body (3.6) is circumferentially provided with a cutting edge (3.6a) for drilling the composite material preform (A). The connecting shaft (3.7) is threadedly connected with the connecting recess (3.5). In the process of drilling the composite material preform (A) by the cutting screw (3) to form a composite material product with a metal ring hole, the metal ring (B) is sleeved on the connecting shaft (3.7).

2. The composite molding tool of claim 1, wherein, A second shaft shoulder (3.4) is arranged on the outer surface of the other end of the screw shaft, and an annular recess (3.3) is formed between the first shaft shoulder (3.2) and the second shaft shoulder (3.4). The diameter of the second shaft shoulder (3.4) is the same as the outer diameter of the metal ring (B). The diameter of the first shaft shoulder (3.2) is greater than the diameter of the second shaft shoulder (3.4).

3. The composite molding tool of claim 2, wherein, The sum of the thickness of the second shaft shoulder (3.4) and the height of the annular recess (3.3) is the same as the thickness of the die top plate (2). The thickness of the cutting body (3.6) is the same as the thickness of the die bottom plate (1). The height of the metal ring (B) is the same as the thickness of the composite material preform (A).

4. The composite molding die of claim 2, wherein Screws are arranged on the second shaft shoulder (3.4) and the cutting body (3.6) respectively for cooperation with the preset threaded holes (a) on the die top plate (2) and the die bottom plate (1).

5. The composite molding die of claim 1, wherein, A hexagonal recess (3.8) is further arranged on the bottom surface of the cutting body (3.6) for loosening the cutting part and the screw body after solidification and molding.

6. The composite molding die of claim 1, wherein, A molding recess (1.1) with three side walls is arranged on the top surface of the die bottom plate (1). Clamping grooves (1.2) are arranged on two opposite side walls of the molding recess (1.1). Clamping edges (2.1) matched with the clamping grooves (1.2) are arranged on two opposite side surfaces of the die top plate (2).

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