Gridding dot matrix composite material and preparation method thereof

Abstract

The invention provides a gridding dot matrix composite material and a preparation method thereof.The preparation method comprises the steps that fiber tows subjected to gum dipping are subjected to grating type laying on a laying path planning tool along a set planning path, and an uncured soft grating structure is obtained; the uncured soft grid structure is transferred to a shaping curing tool, and the planar uncured soft grid structure is converted into a three-dimensional grid structure; and curing heat treatment is conducted on the uncured soft grating structure with the shaping curing tool, and the gridding dot matrix composite material is obtained. The problems that in an existing composite material lattice structure forming technology, fibers are not continuous in the stress direction, the forming precision is reduced due to over-constraint, the material utilization rate is low, the performance is reduced due to interpenetration abrasion, and the forming quality is difficult to control are solved, the raw material utilization rate of the gridding lattice composite material prepared through the method is larger than or equal to 95%, and carbon fibers are 100% continuous; and the problems of forming precision reduction and the like caused by over-constraint do not exist, and each performance can meet the design and use requirements.

Description

Technical Field

[0001] The invention belongs to the technical field of composite material preparation, and in particular relates to a grid lattice composite material and a preparation method thereof. Background Art

[0002] With the continuous improvement of the scientific and technological level in the field of aerospace, the competition among countries in high-tech fields such as high-performance aircraft is becoming increasingly fierce. Faced with the unique service environment and performance requirements, high-performance aircraft have put forward the requirements of lightweight, functional and intelligent structural design. The resin-based carbon fiber composite lattice structure is a new generation of ideal composite material structure integrating material, structure and functional design. It is mainly composed of micro-elements such as plates and rods that are repeatedly arranged according to certain rules to form a spatial plate-rod structure with high porosity, high connectivity and low density. It has excellent properties such as light weight, high specific stiffness, high specific strength, strong spatial designability, and has broad application prospects.

[0003] For the lattice structure of resin-based carbon fiber composite materials, during its composite molding and manufacturing process, material molding and geometric structure molding are carried out simultaneously, so the structural performance is greatly affected by the process, and the advancement of its structural molding process is the key to ensuring its excellent performance. At present, the composite lattice structure is mainly prepared by three methods: interlocking assembly method, pre-laying mold hot pressing method, and interlaced weaving. The interlocking assembly method mainly draws on the preparation method of metal lattices, and prepares the composite lattice structure core through cutting, interlocking, assembly and other processes according to the design drawings; the pre-laying mold hot pressing method mainly lays rectangular prepregs layer by layer on the surface of the corrugated mold, and then uses CNC machining to remove most of the material after the mold is hot-pressed and cured to obtain the composite lattice structure core; the interlaced weaving method uses auxiliary tools to intersperse the fiber bundles into the woven plane layer, so that the two woven plane layers with a certain thickness apart form an overall configuration, and then the resin and the fiber bundles are fused and infiltrated through processes such as spraying, infiltration or RTM, and finally the overall curing is obtained to obtain the lattice structure. At present, the above composite lattice structure preparation methods have the following problems:

[0004] (1) The interlocking assembly method cuts the integrally formed carbon fiber composite material along the length direction, resulting in the discontinuity of the fibers in the entire structure along the force direction, which greatly affects the mechanical properties of the resin-based carbon fiber composite lattice structure. In addition, it is difficult to completely ensure that the size of the entire assembly unit is completely consistent during the cutting process. When the size of the lattice composite material increases, over-constraint is likely to occur, resulting in a decrease in the forming accuracy of the lattice structure.

[0005] (2) Although the pre-laying mold hot pressing method can ensure the continuity of the fiber, the entire structural machining process is a process of removing about 90% of the material, and the removed material cannot be reused, resulting in a waste of molding materials and low raw material utilization.

[0006] (3) Although the interlaced weaving method can ensure fiber continuity and high material utilization, the interlaced weaving process is very likely to cause interlacing wear of the interlaced material (carbon fiber), reducing its mechanical properties. In addition, the overall configuration curing process after weaving has very high requirements on the process. The current spraying, infiltration or RTM processes are difficult to meet the current high-performance aircraft's requirements for its molding quality and molding accuracy. Summary of the invention

[0007] In order to overcome the deficiencies in the prior art, the inventors have conducted intensive research and provided a grid lattice composite material and a preparation method thereof, which solves at least one technical problem in the molding process of the existing resin-based composite material lattice structure, such as non-continuity of fibers in the force direction, over-constraint reducing molding accuracy, low material utilization, performance reduced by interlaced wear, and difficulty in controlling molding quality.

[0008] The technical solution provided by the present invention is as follows:

[0009] In a first aspect, a method for preparing a gridded lattice composite material comprises:

[0010] The fiber tow after being impregnated is laid in a grid-like manner along a set planning path on a laying path planning tool to obtain an uncured soft grid structure;

[0011] Transferring the uncured soft grid structure to a shaping and curing tooling to transform the planar uncured soft grid structure into a three-dimensional grid structure;

[0012] The uncured soft grid structure with the shaped curing tooling is subjected to curing heat treatment to obtain a gridded lattice composite material.

[0013] In a second aspect, a gridded lattice composite material is prepared by the preparation method of the gridded lattice composite material described in the first aspect.

[0014] A grid lattice composite material and a preparation method thereof provided by the present invention have the following beneficial effects:

[0015] (1) The present invention provides a grid lattice composite material and a preparation method thereof, which adopts a combination mold for molding, and has good composite curing molding quality. The "stacking-transfer-shaping and curing" combination mold is used for molding: that is, the stacking path planning tool is used for positioning during stacking, which can ensure the accuracy of the stacking position and the consistency of the stacking quality; at the same time, after the grid lattice composite material is stacked, the soft metal plate stacking transfer tool is used to transfer the uncured soft grid structure after stacking to the shaping and curing tool; finally, the shaping and curing tool uses a positive and negative combination mold to control the surface accuracy of the grid composite material, ensuring that the molding quality and molding accuracy of the grid composite material meet the use requirements.

[0016] (2) The present invention provides a grid lattice composite material and a preparation method thereof, wherein all fibers are continuous along the length direction and the mechanical properties of the component are good. After the grid lattice path planning is performed on the grid composite material, either a monofilament fiber continuous surrounding layering method or a multi-bundle fiber layered layering method can be used, and all fibers can be stacked and formed along the length direction, without the process of fiber machining or cutting, and all carbon fibers can achieve 100% continuity, which is more conducive to ensuring the maintenance of the mechanical properties of the grid lattice composite material structure.

[0017] (3) The present invention provides a grid lattice composite material and a preparation method thereof, wherein the molding process does not involve a "machining and material removal" process, and the material utilization rate is high. The uniform raw materials are used to realize the grid lattice path planning, and other non-grid structure areas are occupied by rigid molds during the lattice composite material molding process, thereby ensuring that all raw materials are concentrated in the grid lattice structure area during the stacking and molding process, and the carbon fiber composite material after molding is all located in the structure area, without the need for "machining and material removal" of the "non-structure area", and only a small amount of process surplus raw materials in the boundary area need to be removed, which can ensure that the raw material utilization rate is ≥ 95%.

[0018] (4) The present invention provides a gridded lattice composite material and a preparation method thereof, wherein all raw materials are formed in one step using the same process, and the quality consistency is high. All raw materials are formed in one step using the same process, and the quality consistency is high. There is no problem of over-constraint or poor quality consistency of the lattice composite material due to differences between the raw materials. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a schematic diagram of the process of preparing the grid lattice composite material;

[0020] Figure 2 This is a schematic diagram of the path planning for a grid lattice composite material;

[0021] Figure 3 A schematic diagram of the structure of the tooling for laying path planning;

[0022] Figure 4 It is a schematic diagram of the structure of the ply transfer tooling;

[0023] Figure 5 It is a structural schematic diagram of the shaping and curing tooling;

[0024] Figure 6 Schematic diagram of the grid lattice composite material structure and molding process. Figure (a) shows the plane grid-type ply, Figure (b) shows the ply-transfer process, and Figure (c) shows the final state after the ply transfer and shaping is completed. DETAILED DESCRIPTION

[0025] The following detailed description of the present invention will make the features and advantages of the present invention more clear and explicit.

[0026] The word “exemplary” is used exclusively herein to mean “serving as an example, example, or illustration.” Any embodiment described herein as “exemplary” is not necessarily to be construed as preferred or advantageous over other embodiments.

[0027] The present invention provides a grid lattice composite material, such as Figure 1 As shown, it mainly includes: tooling preparation M1, raw material preparation M2, grid-type ply M3, ply transfer M4, and shaping and curing M5 processes.

[0028] Tool preparation M1: Prepare the lattice structure laying path planning tool, layer transfer tool, shaping and curing tool, check the tool properties, degrease and clean the tool, and process the isolation materials such as Teflon on the surface.

[0029] Raw material preparation M2: The raw material of the grid lattice structure is prepared by a one-step impregnation and spreading method of a single-filament bundle fiber or a two-step composite slitting method of a multi-filament bundle fiber, and the raw material is a fiber bundle impregnated with glue.

[0030] The raw materials used in the gridded lattice composite material of the present invention are formed once using the same process. It only needs to control the process parameters of the forming process to remain consistent to obtain continuous, uniform and consistent quality raw materials. The raw materials used in the gridded lattice composite material of the present invention can be made by a one-step impregnation and yarn spreading method for single-filament bundle fibers or a two-step composite slitting method for multiple-filament bundle fibers. The one-step impregnation and yarn spreading method for single-filament bundle fibers passes through the same traction roller, flattening roller, dipping roller, flattening roller, and traction roller. It only needs to ensure that the roller tension, the gap between each roller, the roller speed, and the roller temperature are kept within a reasonable and uniform range between the rollers. The two-step composite slitting method for multiple-filament bundle fibers only needs to control the slitting width of the slitting machine to remain consistent, and the fixed-width raw materials that meet the requirements can be obtained online. All raw materials are formed once using the same process, with high quality consistency, and there is no problem of over-constraint or poor quality consistency of the lattice composite material caused by differences between the raw materials.

[0031] Grid-type ply M3: The preparation method of the grid lattice composite material of the present invention adopts unified raw materials through grid lattice path planning. Other non-grid structure areas are occupied by the laying path planning tooling during the lattice composite material forming process, thereby ensuring that all raw materials are concentrated in the grid lattice structure area during the laying and forming process. The carbon fiber composite materials after forming are all located in the structural area. There is no need to "machine and remove materials" in the "non-structural area". Only a small amount of process surplus raw materials in the boundary area need to be removed, which can ensure that the raw material utilization rate is ≥95%.

[0032] Laying path planning tooling Figure 2and Figure 3 As shown, it includes a substrate 11 and placeholders 12 arranged in an array on the substrate. The shape of the placeholders 12 is consistent with the shape of the structural unit in the lattice composite material, such as a flat hexagon, a triangle, etc. The placeholders 12 in adjacent rows are arranged in a staggered manner, and the placeholders 12 in adjacent columns are arranged in a staggered manner, and a stacking area of ​​the raw materials is formed between the placeholders 12. Guide columns 13 are arranged in rows on both sides of the placeholders 12 arranged in an array. When a single-fiber bundle continuous surrounding laying method is adopted, they serve as force columns for the single-fiber bundle to turn and wind, and when a multi-bundle fiber layered laying method is adopted, they serve as guide columns for multiple bundles of fibers to enter the stacking path planning tooling.

[0033] The method for preparing the gridded lattice composite material of the present invention can use either a single-fiber bundle continuous surrounding layering method or a multi-bundle fiber layering method by performing grid-type lattice path planning on the gridded composite material. The single-tow fiber continuous wrap-around laying method is specifically as follows: after a single-tow fiber enters the laying path planning tooling from the first end of the substrate, it is laid obliquely upward along the gaps of the array-arranged placeholders, reaches the second end, the third end or the fourth end of the substrate, reverses around the guide column or the end placeholder, lays along the gaps of the array-arranged placeholders and returns to the first end, and then continues to reverse around the guide column or the end placeholder, repeats the above laying-turning-laying steps to obtain a unidirectional laying structure; another single-tow fiber enters the laying path planning tooling from the first end of the substrate, and is laid obliquely downward along the gaps of the array-arranged placeholders. The laying and turning methods are consistent with the single-tow fiber laid obliquely upward, and it forms an intersection with the single-tow fiber laid obliquely upward to obtain a grid lattice structure, and the two-tow fiber can be laid at the same time. Among them, the first end and the second end of the substrate are two opposite ends in the length direction of the substrate, and the third end and the fourth end are two opposite ends in the width direction of the substrate.

[0034] When the single tow fibers laid obliquely upward cross the single tow fibers laid obliquely downward, the single tow fibers laid obliquely upward cross in accordance with the positional relationship of being located once below and once above the single tow fibers laid obliquely downward. At this time, the single tow fibers laid obliquely upward or the single tow fibers laid obliquely downward present a continuous S shape in the thickness direction, and are cross-laid with each other, which is beneficial to the improvement of the mechanical properties of the grid lattice structure. By adopting the stacking method, the problem of interlaced wear of the interlaced object (carbon fiber) and reduction of its mechanical properties in the interlaced weaving process in the interlaced weaving method is avoided.

[0035] The multi-bundle fiber layering method is specifically as follows: after two groups of tow fibers enter the stacking path planning tooling from the first end of the substrate, they are laid obliquely upward and obliquely downward along the gaps of the placeholder blocks arranged in the array, reaching the second end, the third end or the fourth end of the substrate. The tow fibers reaching the third end or the fourth end of the substrate extend from the edge to the second end and are led out; the single group of tow fibers laid obliquely upward and the single group of tow fibers laid obliquely downward form an intersection to obtain a grid lattice structure, in which each group of tow fibers includes multiple tow fibers, and the two groups of tow fibers can be laid at the same time. Similarly, when the tow fibers laid obliquely upward cross the tow fibers laid obliquely downward, the tow fibers laid obliquely upward cross in sequence according to the positional relationship of being once below and once above the tow fibers laid obliquely downward.

[0036] Both the single-fiber continuous wraparound laying method and the multi-fiber layered laying method can make all the fibers stacked and formed along the length direction. There is no fiber machining or cutting process. All carbon fibers can be 100% continuous, which is more conducive to maintaining the mechanical properties of the grid lattice composite material structure.

[0037] Layer transfer M4: Use the soft metal plate layer transfer tool to transfer the uncured soft grid structure after stacking to the shaping and curing tool.

[0038] like Figure 4 As shown, the ply transfer tooling is obtained by drilling holes in a soft metal plate, and the shape and arrangement of the holes on the soft metal plate match the shape and arrangement of the placeholders 12 and guide posts 13 arranged in an array on the ply path planning tooling. The ply transfer tooling is stacked on the ply path planning tooling, and the ply path planning tooling is taken out after flipping, and the uncured soft grid structure is transferred to the ply transfer tooling.

[0039] like Figure 5 As shown, the shaping and curing tooling includes a female mold with a serrated working surface and multiple groups of male molds with conical working surfaces. The surfaces of the female molds are successively an uncured soft grid structure and a ply transfer tooling. The male molds are extruded from the side of the ply transfer tooling to make the uncured soft grid structure and the ply transfer tooling fit with the serrated working surface of the female mold, thereby converting the planar uncured soft grid structure into a three-dimensional grid structure.

[0040] like Figure 6 As shown, the uncured soft grid structure on the ply transfer tooling is a flat grid-type ply. After being transferred to the shaping and curing tooling, it is transformed into a three-dimensional grid structure through the cooperation of the positive and negative molds.

[0041] Forming and curing M5: The uncured soft grid structure with the forming and curing tooling is subjected to curing heat treatment to obtain a gridded lattice composite material.

[0042] The present invention solves the problems in the existing composite material lattice structure molding technology, such as non-continuous fibers in the force direction, reduced molding accuracy due to over-constraint, low material utilization, reduced performance due to interlaced wear, and difficult to control molding quality. The grid lattice composite material prepared by this method has a raw material utilization rate of ≥95%, 100% continuous carbon fiber, and does not have problems such as reduced molding accuracy due to over-constraint. All performances can meet the design and use requirements, can match the needs of high-performance aircraft for their own structures, and can be subsequently applied to various structural and functional integrated high-performance aircraft structures such as lightweight load-bearing structures, integrated electromagnetic functions, and integrated heat-insulating structures.

[0043] The present invention has been described in detail above in conjunction with specific implementations and exemplary examples, but these descriptions cannot be understood as limiting the present invention. Those skilled in the art understand that, without departing from the spirit and scope of the present invention, a variety of equivalent substitutions, modifications or improvements may be made to the technical solution of the present invention and its implementation methods, all of which fall within the scope of the present invention. The scope of protection of the present invention shall be subject to the attached claims.

[0044] The contents not described in detail in the specification of the present invention belong to the common knowledge of those skilled in the art.

Claims

1. A method for preparing a gridded lattice composite material, characterized in that: include: The fiber tow after being impregnated is laid in a grid-like manner along a set planning path on a laying path planning tool to obtain an uncured soft grid structure; Transferring the uncured soft grid structure to a shaping and curing tooling to transform the planar uncured soft grid structure into a three-dimensional grid structure; The uncured soft grid structure with the shaped curing tooling is subjected to curing heat treatment to obtain a gridded lattice composite material.

2. The method for preparing the gridded lattice composite material according to claim 1, characterized in that: The stacking path planning tool includes a substrate and placeholders arranged in an array on the substrate, the shape of the placeholders is consistent with the shape of the structural unit in the lattice composite material, the placeholders in adjacent rows are arranged in a staggered manner, the placeholders in adjacent columns are arranged in a staggered manner, and a stacking area of ​​the raw material is formed between the placeholders; Guide columns are arranged in rows on both sides of the array-arranged placeholders.

3. The method for preparing the gridded lattice composite material according to claim 1, characterized in that: The method of using the impregnated fiber tows to perform grid-type layering along a set planned path on a laying path planning tool includes using a single-tow fiber continuous surrounding layering method to perform grid-type layering, specifically: After a single tow fiber enters the stacking path planning tooling from the first end of the substrate, it is laid obliquely upward along the gaps between the placeholders arranged in an array, reaches the second, third or fourth end of the substrate, goes around the guide column or the end placeholder in the opposite direction, is laid along the gaps between the placeholders arranged in an array and returns to the first end, then continues to go around the guide column or the end placeholder in the opposite direction, repeats the above-mentioned laying-turning-laying steps to obtain a unidirectional laying structure; then another single tow fiber enters the stacking path planning tooling from the first end of the substrate, is laid obliquely downward along the gaps between the placeholders arranged in an array, and the laying and turning methods are consistent with the single tow fiber laid obliquely upward, and crosses with the single tow fiber laid obliquely upward to obtain a grid lattice structure; wherein the first and second ends of the substrate are two opposite ends in the length direction of the substrate, and the third and fourth ends are two opposite ends in the width direction of the substrate.

4. The method for preparing the gridded lattice composite material according to claim 3, characterized in that: When the single tow fibers laid obliquely upward cross the single tow fibers laid obliquely downward, the single tow fibers laid obliquely upward cross in a recursive positional relationship of once below and once above the single tow fibers laid obliquely downward, and the single tow fibers laid obliquely upward or the single tow fibers laid obliquely downward present a continuous S-shape in the thickness direction and are cross-laid with each other.

5. The method for preparing the gridded lattice composite material according to claim 1, characterized in that: The method of using the impregnated fiber bundles to perform grid-type layering along a set planned path on a laying path planning tool includes using a multi-bundle fiber layering method to perform grid-type layering, specifically: After the two groups of tow fibers enter the stacking path planning tooling from the first end of the substrate, they are laid obliquely upward and downward along the gaps of the array-arranged placeholders to reach the second end, the third end or the fourth end of the substrate. The tow fibers reaching the third end or the fourth end of the substrate extend from the edge to the second end and are led out; the single group of tow fibers laid obliquely upward and the single group of tow fibers laid obliquely downward form an intersection to obtain a grid lattice structure; each group of tow fibers includes multiple bundles of tow fibers.

6. The method for preparing the gridded lattice composite material according to claim 5, characterized in that: When the tow fibers laid obliquely upward cross the tow fibers laid obliquely downward, the tow fibers laid obliquely upward cross in a positional relationship of being located once below and once above the tow fibers laid obliquely downward.

7. The method for preparing the gridded lattice composite material according to claim 1, characterized in that: The transferring of the uncured soft grid structure to the shaping and curing tooling includes using a soft metal plate ply transfer tooling to transfer the uncured soft grid structure after the plying is completed to the shaping and curing tooling; the ply transfer tooling is obtained by drilling holes in the soft metal plate, and the shape and arrangement of the holes on the soft metal plate match the shape and arrangement of the placeholders and guide columns arranged in an array on the ply path planning tooling; The ply transfer tool is stacked on the ply path planning tool, and the ply path planning tool is taken out after being flipped over, and the uncured soft grid structure is transferred to the ply transfer tool.

8. The method for preparing the gridded lattice composite material according to claim 1, characterized in that: The shaping and curing tooling includes a female mold with a serrated working surface and multiple groups of male molds with conical working surfaces. The surface of the female mold is an uncured soft grid structure and a ply transfer tooling in sequence. The male mold is extruded from the side of the ply transfer tooling to make the uncured soft grid structure and the ply transfer tooling fit with the serrated working surface of the female mold, so that the planar uncured soft grid structure is converted into a three-dimensional grid structure.

9. The method for preparing the gridded lattice composite material according to claim 1, characterized in that: The resin-impregnated fiber bundles are formed in one step by adopting the same process.

10. A gridded lattice composite material, characterized in that: The invention is prepared by the preparation method of the gridded lattice composite material according to any one of claims 1 to 9.

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