Large-window cabin net size forming method

Abstract

The invention provides a large-window cabin net size forming method. The large-window cabin net size forming method comprises the steps that firstly, discharging operation is conducted; then determining the laying position and laying reference of the carbon fiber prepreg; then, cabin laying is conducted, vacuumizing is conducted continuously for compaction in the laying process, the surface laying quality is checked after compaction is completed, and subsequent prepreg laying is conducted after wrinkles are ironed; window position prepreg laying is conducted alternately in the cabin whole laying process, and window position prepreg is laid with the edge of a window occupying block as the reference; then the positioning pieces at the four corners of the occupying block are removed, and limiting pieces are inserted into two oblong holes symmetrically formed in the middle of the occupying block; then curing and demolding are conducted; and finally inspecting. On the premise that the window size precision is guaranteed, the cabin window machining procedure is avoided, the product production cost is reduced, the production period is shortened, and meanwhile the defects of thread splitting and layering easily generated in the composite product machining process are overcome.

Description

Technical Field

[0001] The present invention belongs to the technical field of composite material forming and manufacturing, and particularly relates to a net-size forming method for a large-window cabin body. Background Art

[0002] The lightweight carbon fiber composite cabin body structure has the advantages of light weight, high strength and designability, and is widely used in aerospace structures. In order to meet the needs of communication and telemetry between payloads and ground stations during flight, the cabin body needs to have good radio wave penetrability. Therefore, wave-transmitting windows need to be specially designed at specific positions of the cabin body. In addition, in order to facilitate the assembly, maintenance and replacement of various instruments inside the cabin body before flight, operation windows need to be designed on the surface of the cabin body. In the existing process solutions, for opening windows on the surface of the cabin body, machining methods are often used for preparation. For some cabin body structures with more complex profiles, five-axis machine tools need to be used for machining, resulting in higher processing costs and longer production cycles. Moreover, during the processing of composite material products, defects such as splitting and delamination are likely to occur, and problems such as wrinkles and bulges caused by the thermal expansion of the mold during the curing heating process, as Figure 3 and Figure 4 shown. Therefore, it is necessary to improve the existing forming method for large-window cabin bodies. Summary of the Invention

[0003] In view of this, the present invention aims to overcome the defects in the prior art and proposes a net-size forming method for a large-window cabin body.

[0004] To achieve the above object, the technical solution of the present invention is realized as follows:

[0005] A net-size forming method for a large-window cabin body, comprising the following steps:

[0006] S1. Perform blanking of the overall carbon fiber prepreg for the cabin body and blanking of the carbon fiber prepreg at the window position;

[0007] S2. Determine the laying position and laying reference of the carbon fiber prepreg;

[0008] S3. Perform laying of the cabin body, continuously evacuate and compact during the laying process, check the surface laying quality after compaction is completed, iron out the wrinkles and then perform subsequent prepreg laying;

[0009] S4. Intermittently perform laying of the prepreg at the window position during the overall laying of the cabin body, and lay the prepreg at the window position with the edge of the window placeholder block as the reference;

[0010] S5. Remove the positioning parts at the four corners of the placeholder block, and insert limiting parts into two long circular holes symmetrically arranged in the middle of the placeholder block (to ensure that the placeholder block does not move with the expansion of the mold body during the heating of the mold and cause extrusion to the prepreg);

[0011] S5. Vacuum coat the product, and then transfer the mold to a heating and pressing device for curing.

[0012] S6. After curing is completed, remove the positioning pins in the dummy blocks and demold the product.

[0013] S7. Transfer the product to the inspection area and conduct dimensional and internal quality flaw detection inspections on the product.

[0014] Furthermore, in step S1, classify and place the prepregs according to the shape and number of prepreg blocks, and mark the quantity.

[0015] Furthermore, in step S2, use laser projection to project the laying positions and laying benchmarks of the carbon fiber prepregs.

[0016] Furthermore, in step S5, the positioning members at the four corners of the dummy blocks include two positioning pins and two screws, and the two positioning pins are used for the limiters of the two long circular holes.

[0017] Furthermore, in step S5, the curing temperature is 180 °C.

[0018] Furthermore, in step S6, after curing is completed, clean the surface of the product.

[0019] Compared with the prior art, the present invention has the following advantages:

[0020] The present invention provides a method for forming the net size of a large-window cabin body. On the premise of ensuring the dimensional accuracy of the window, it avoids the processing procedures of the cabin body window, reduces the production cost of the product, saves the production cycle, and at the same time avoids the splitting and delamination defects that are prone to occur during the processing of composite material products. In addition, by optimizing the mold structure, it improves the problems of wrinkles and bulges caused by the thermal expansion of the mold during the curing heating process due to the limitations of the positioning pins and fixing screws, and improves the comprehensive performance and aesthetics of the product. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The drawings constituting a part of the present invention are used to provide a further understanding of the present invention. The schematic embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation to the present invention. In the drawings:

[0022] Figure 1 is a schematic diagram of the mold of the present invention;

[0023] Figure 2 is a schematic diagram of the mold of the prior art;

[0024] Figure 3 and Figure 4 is a schematic diagram of the defects of the prior art. Detailed implementation mode

[0025] It should be noted that, without conflict, the embodiments and features in the embodiments of the present invention can be combined with each other.

[0026] In the description of the present invention, it should be understood that the orientation or positional relationship indicated by the terms "center", "longitudinal", "transverse", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus cannot be understood as a limitation to the present invention. In addition, the terms "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the quantity of the indicated technical features. Thus, the features defined with "first", "second", etc. may explicitly or implicitly include one or more of such features. In the description of the present invention, unless otherwise stated, the meaning of "a plurality" is two or more.

[0027] In the description of the present invention, it should be noted that unless otherwise clearly specified and limited, the terms "installation", "connection", "connection" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood through specific situations.

[0028] The present invention will be described in detail below with reference to the drawings and in combination with embodiments.

[0029] A method for forming the net size of a large-window cabin body, as Figure 1 shown, includes the following steps:

[0030] S1. Cut the carbon fiber prepreg for the whole cabin body and the carbon fiber prepreg at the window position;

[0031] S2. Determine the laying position and laying reference of the carbon fiber prepreg;

[0032] S3. Lay the cabin body. During the laying process, continuously evacuate to compact. After the compaction is completed, check the surface laying quality. After ironing out the wrinkles, perform the subsequent laying of the prepreg;

[0033] S4. During the overall layup process of the cabin body, prepreg is laid at the window position in an interleaved manner. The prepreg at the window position is laid with the edge of the window placeholder block as the reference; the dimensional accuracy of the window is ensured by the placeholder block 4 on the mold surface.

[0034] S5. Remove the positioning parts 1 at the four corners of the placeholder block, and insert the limiting parts 3 into the two long round holes 2 symmetrically arranged in the middle of the placeholder block.

[0035] S5. Vacuum coat the product, and then transfer the mold 5 to the heating and pressurizing equipment for curing; preferably, the curing temperature is 180 °C.

[0036] S6. After curing is completed, clean the surface of the product without any impurities; then take out the positioning pin 6 in the placeholder block and demold the product.

[0037] S7. Transfer the product to the inspection area, and conduct dimensional and internal quality flaw detection inspections on the product.

[0038] In step S1, the prepreg is classified and placed according to the shape and number of the prepreg blocks, and the quantity is marked.

[0039] In step S2, using laser projection, project the laying position and laying reference of the carbon fiber prepreg.

[0040] In the present invention, to avoid the influence of the placeholder block near the mold edge squeezing the prepreg to generate wrinkles due to the thermal expansion of the mold, the installation and positioning structure of the window placeholder block has been specially designed. The positioning parts at the four corners of the placeholder block include two positioning pins and two screws, and the two positioning pins can be used for the limiting parts of the subsequent two long round holes.

[0041] Preferably, the two screws are arranged diagonally on the placeholder block, and the two positioning pins are arranged diagonally on the placeholder block. Such a positioning block structure design ensures that the placeholder block does not move with the expansion of the mold body during the mold heating process to squeeze the prepreg, which can effectively improve the product forming quality. It improves the defects of the existing technology mold forming method as shown in Figure 2 the figure.

[0042] The present invention provides a net size forming method for a large-window cabin body. On the premise of ensuring the dimensional accuracy of the window, it avoids the cabin body window processing procedure, reduces the product production cost, saves the production cycle, and at the same time avoids the splitting and delamination defects easily generated during the processing of composite material products. In addition, by optimizing the mold structure, it improves the problems of wrinkles and bulges caused by the thermal expansion of the mold during the curing heating process, and improves the comprehensive performance and aesthetics of the product.

[0043] The above are only the preferred embodiments of the present invention, and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A method for forming a large window cabin with a net size, characterized in that: The steps include: S1. Cutting carbon fiber prepreg for the entire cabin and the window position; S2. Determine the carbon fiber prepreg ply position and laying reference; S3, laying out the cabin, continuously vacuuming and compacting during the laying process, checking the surface laying quality after the compaction, and laying out the subsequent prepreg after smoothing out the wrinkles; S4. During the whole laying process of the cabin, the prepreg at the window position is laid out interspersed, and the prepreg at the window position is laid out based on the edge of the window placeholder block; S5, remove the positioning pieces at the four corners of the placeholder block, and insert the limiting pieces into the two oblong holes symmetrically arranged in the middle of the placeholder block; S5, vacuum coating the product, and then transferring the mold to a heating and pressurizing device for curing; S6. After curing is completed, remove the positioning pins in the placeholder block and demould the product; S7. The products are transported to the inspection area for dimensional and internal quality inspection.

2. A method for forming a large window cabin net size according to claim 1, characterized in that: In step S1, the prepregs are classified and placed according to the shapes and numbers of the prepreg blocks, and the quantities are marked.

3. A method for forming a large window cabin net size according to claim 1, characterized in that: In step S2, laser projection is used to project the carbon fiber prepreg ply position and laying reference.

4. A method for forming a large window cabin net size according to claim 1, characterized in that: In step S5, the positioning members at the four corners of the placeholder block include two positioning pins and two screws, wherein the two positioning pins are used as the limiting members of the two oblong holes.

5. The method for forming a large window cabin net size according to claim 1, characterized in that: In step S5, the curing temperature is 180°C.

6. A method for forming a large window cabin net size according to claim 1, characterized in that: In step S6, after curing is completed, the product surface is cleaned.

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