Manufacturing process of large-size thin-walled composite shell with omega cross section

Abstract

The application provides a manufacturing process of a large-size thin-wall composite shell with an omega-shaped cross section, 0-degree direction prepreg is laid on the upper end surface of a male block and the upper surface of a bottom plate frame, and the lay-up is turned down to the surface of a tapered section of the male block to form a lap joint part on the surface of the tapered section of the male block; then 90-degree direction prepreg is alternately laid, and the lay-up is turned down to the surface of the tapered section of the male block to form a lap joint part on the surface of the tapered section of the male block; the lay-up is repeated, and the butt joints of the lay-ups are staggered with each other during the laying process; curing is carried out after the laying; and demolding is carried out after the curing. The manufacturing process provided by the application can effectively improve the continuity of fibers at the top end, the tapered section and the bottom flange of the product, and effectively ensure the flatness of the top end and the bottom flange, greatly improving the defects that the local position of the product is prone to collapse or warping, and improving the product quality.

Description

Technical Field

[0001] This invention belongs to the field of aerospace composite material product technology, and in particular relates to a manufacturing process for a large-size thin-walled composite material shell with an Ω-shaped cross section. Background Technology

[0002] High-temperature resistant, large-sized, special-structure thin-shell composite material products typically exhibit poor resistance to deformation. For large-sized thin-walled products with an Ω-shaped cross-section, during manufacturing, the top structure is prone to collapse, the bottom flange structure is prone to warping, and large gaps easily form between the top structure and the conical segment, as well as between the bottom flange and the conical segment. These defects can even occur simultaneously, and existing production processes struggle to control them, resulting in high manufacturing difficulty, low yield, unreliable product quality, difficulty in post-molding finishing, and high scrap rates, leading to persistently high production costs. Therefore, it is necessary to improve the performance of such large-sized thin-walled composite material products through process improvements. Summary of the Invention

[0003] In view of this, the present invention aims to overcome the deficiencies in the prior art and proposes a manufacturing process for large-size thin-walled composite material shells with an Ω-shaped cross section.

[0004] To achieve the above objectives, the technical solution created by this invention is implemented as follows:

[0005] A manufacturing process for a large-size thin-walled composite material shell with an Ω-shaped cross-section includes the following steps:

[0006] (1) A molding die for the shell is prepared by a positive mold forming method. The molding die includes a base frame and a positive mold protrusion on the base frame. The upper end face of the positive mold protrusion is parallel to the surface of the base frame.

[0007] (2) Using the upper end face of the male mold protrusion and the upper surface of the base plate frame as references, prepreg in the 0° direction is laid alternately; when laying the prepreg in the 0° direction on the upper end face of the base plate frame, the ply is turned upward to the surface of the conical section of the male mold protrusion, and when laying the prepreg in the 0° direction on the upper end face of the male mold protrusion, the ply is turned downward to the surface of the conical section of the male mold protrusion, so that the prepreg laid with the upper end face of the male mold protrusion and the upper surface of the base plate frame as references forms an overlapping part on the surface of the conical section of the male mold protrusion;

[0008] (3) Then, taking the upper end face of the male mold protrusion and the upper surface of the base plate frame as references, the prepreg in the 90° direction is laid alternately; when laying the prepreg in the 90° direction of the upper end face of the base plate frame, the ply is turned up to the surface of the conical section of the male mold protrusion, and when laying the prepreg in the 90° direction of the upper end face of the male mold protrusion, the ply is turned down to the surface of the conical section of the male mold protrusion, so that the prepreg laid with the upper end face of the male mold protrusion and the upper surface of the base plate frame as references forms an overlapping part on the surface of the conical section of the male mold protrusion;

[0009] (4) Repeat steps (2)-(3) alternately, and stagger the joints of each layer during the laying process;

[0010] (5) Curing is carried out after the tiling is completed;

[0011] (6) After curing, demold to obtain a large-sized thin-walled composite material shell with an Ω-shaped cross section.

[0012] Furthermore, the male mold protrusion and the base plate frame are integrally formed structures.

[0013] Furthermore, lifting rings are symmetrically provided on the outer edge of the base plate frame.

[0014] Furthermore, several weight-reduction holes are provided on the side wall of the base plate frame.

[0015] Furthermore, before laying the prepreg, a release agent is applied to the surface of the base plate frame and the surface of the male mold protrusion.

[0016] Furthermore, after the layup is completed, auxiliary materials are wrapped around the prepreg product in sequence, including PTFE cloth, filter paper, release film, breathable felt, and vacuum bag film, and then vacuum treatment is performed.

[0017] Furthermore, the curing process includes: pressurizing at room temperature to 0.3 MPa, first heating to 160°C and holding for 1 hour, then pressurizing to 0.6 MPa, followed by holding at 180°C for 2 hours, 200°C for 2 hours, and 230°C for 2 hours in sequence.

[0018] Compared with existing technologies, the present invention has the following advantages:

[0019] The manufacturing process provided by this invention can effectively improve the continuity of fibers in the top, conical section and bottom flange of the product. At the same time, it can also effectively ensure the flatness of the top and bottom flanges, greatly improving the defects of local collapse or warping in previous products, improving product quality. The process is simple and easy to implement. Attached Figure Description

[0020] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments and descriptions of the invention are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings:

[0021] Figure 1 A schematic diagram illustrating the molding die used in this invention;

[0022] Figure 2 A schematic diagram of the composite material laying reference for creating a large-size thin-walled composite material shell with an Ω-shaped cross-section for this invention;

[0023] Figure 3 A schematic diagram of the cross-sectional structure of a large-size thin-walled composite material shell with an Ω-shaped cross-section, which is the basis for this invention. Detailed Implementation

[0024] It should be noted that, unless otherwise specified, the embodiments and features described in the present invention can be combined with each other.

[0025] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicating orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation on this invention. Furthermore, the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, features defined with "first," "second," etc., may explicitly or implicitly include one or more of that feature. In the description of this invention, unless otherwise stated, "a plurality of" means two or more.

[0026] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art will understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0027] The invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0028] A manufacturing process for large-size thin-walled composite material shells with an Ω-shaped cross-section, such as Figures 1 to 3 As shown, it includes the following steps:

[0029] (1) A molding die for the shell is prepared by a positive mold forming method. The molding die includes a base frame 1 and a positive mold protrusion 2 protruding on the base frame. The upper end face of the positive mold protrusion is parallel to the surface of the base frame.

[0030] (2) Using the upper end face of the male mold protrusion and the upper surface of the base plate frame as references, prepreg in the 0° direction is laid alternately; when laying the prepreg in the 0° direction on the upper end face of the base plate frame, the layup is turned upward to the surface of the conical section of the male mold protrusion, and when laying the prepreg in the 0° direction on the upper end face of the male mold protrusion, the layup is turned downward to the surface of the conical section of the male mold protrusion, so that the prepreg laid with the upper end face of the male mold protrusion and the upper surface of the base plate frame as references forms an overlapping part on the surface of the conical section of the male mold protrusion. Usually, the overlapping part formed in this step covers more than 1 / 2 of the total surface area of ​​the conical section of the male mold protrusion.

[0031] (3) Then, using the upper end face of the male mold protrusion and the upper surface of the base plate frame as references, the prepreg in the 90° direction is laid alternately. When laying the prepreg in the 90° direction of the upper end face of the base plate frame, the ply is turned upward to the surface of the male mold protrusion cone section. When laying the prepreg in the 90° direction of the upper end face of the male mold protrusion, the ply is turned downward to the surface of the male mold protrusion cone section. This makes the prepreg laid with the upper end face of the male mold protrusion and the upper surface of the base plate frame as references form an overlapping part on the surface of the male mold protrusion cone section. Usually, the overlapping part formed in this step covers more than 1 / 2 of the total area of ​​the surface of the male mold protrusion cone section.

[0032] (4) Repeat steps (2)-(3) to alternately lay up the layers, and stagger the joints of each layer during the laying process. It should be noted that during the layup operation, the overlapping part only needs to cover more than 1 / 2 of the total surface area of ​​the male mold protrusion cone section to achieve the layup operation of the large-size thin-walled composite material shell of the Ω-shaped section. The process is simple, convenient and easy to implement. The difficulty of prepreg cutting, cutting and slitting is reduced, saving materials and labor costs. In addition, it effectively avoids defects such as collapse and warping.

[0033] (5) Curing is carried out after the tiling is completed;

[0034] (6) After curing, demold to obtain a large-sized thin-walled composite material shell with an Ω-shaped cross section.

[0035] It should be noted that after the prepreg is laid, auxiliary materials are wrapped. In sequence, PTFE cloth, filter paper, release film, breathable felt, and vacuum bag film are wrapped around the outside of the prepreg product, followed by vacuuming. Specifically, when wrapping the PTFE cloth, care should be taken to cut and overlap at the corners to prevent gaps. When laying the filter paper, it is mainly laid on the upper and lower surfaces of the prepreg. When wrapping the release film, allowance should be left at the corners. When wrapping the breathable felt, care should be taken to cut and overlap at the corners. When wrapping the vacuum bag, allowance should be left at the corners to prevent gaps.

[0036] It should be noted that in this invention, the 0° and 90° prepreg directions are relative. Specifically, when a layer of prepreg is laid on the reference of the molding die, the 0° direction refers to the prepreg layer perpendicular to its fiber direction, while the 90° direction refers to the prepreg layer perpendicular to its fiber direction. Furthermore, in this invention, the fiber direction of the prepreg layer flanging to the male mold punch cone section is not strictly limited; it can be laid naturally, making the operation simpler and more efficient. Simultaneously, since the fiber directions of the 0° and 90° prepreg layers laid according to the reference are approximately perpendicular after flanging to the male mold punch cone section, this is sufficient to guarantee the product's performance.

[0037] In the specific design, the male mold protrusion and the base plate frame are integrally formed. The outer edge of the base plate frame is symmetrically equipped with lifting rings 6. Several weight-reducing holes can be opened on the side walls of the base plate frame. Before laying the prepreg, a release agent is applied to the surface of the base plate frame and the surface of the male mold protrusion.

[0038] The curing regime for the above manufacturing process includes: pressurizing at room temperature to 0.3 MPa, first heating to 160°C and holding for 1 hour, then pressurizing to 0.6 MPa, followed by sequential holding at 180°C for 2 hours, 200°C for 2 hours, and 230°C for 2 hours. In practice, the mold temperature can be monitored using thermocouples. During the cooling process, when the temperature drops to 60°C, the pressure is released, the machine is stopped, and the product is removed from the can.

[0039] The manufacturing process provided by this invention can effectively improve the continuity of fibers in the top, conical section and bottom flange of the product. At the same time, it can also effectively ensure the flatness of the top and bottom flanges, greatly improving the defects of local collapse or warping in previous products, improving product quality. The process is simple and easy to implement.

[0040] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A manufacturing process for a large-size thin-walled composite material shell with an Ω-shaped cross-section, characterized in that, Includes the following steps: (1) A molding die for the shell is prepared by a positive mold forming method. The molding die includes a base frame and a positive mold protrusion on the base frame. The upper end face of the positive mold protrusion is parallel to the surface of the base frame. (2) Using the upper end face of the male mold protrusion and the upper surface of the base plate frame as references, prepreg in the 0° direction is laid alternately; when laying the prepreg in the 0° direction on the upper end face of the base plate frame, the ply is turned upward to the surface of the conical section of the male mold protrusion, and when laying the prepreg in the 0° direction on the upper end face of the male mold protrusion, the ply is turned downward to the surface of the conical section of the male mold protrusion, so that the prepreg laid with the upper end face of the male mold protrusion and the upper surface of the base plate frame as references forms an overlapping part on the surface of the conical section of the male mold protrusion; (3) Then, taking the upper end face of the male mold protrusion and the upper surface of the base plate frame as references, the prepreg in the 90° direction is laid alternately; when laying the prepreg in the 90° direction of the upper end face of the base plate frame, the ply is turned up to the surface of the conical section of the male mold protrusion, and when laying the prepreg in the 90° direction of the upper end face of the male mold protrusion, the ply is turned down to the surface of the conical section of the male mold protrusion, so that the prepreg laid with the upper end face of the male mold protrusion and the upper surface of the base plate frame as references forms an overlapping part on the surface of the conical section of the male mold protrusion; (4) Repeat steps (2)-(3) to alternate the layup, and stagger the joints of each layup during the laying process; (5) Curing is carried out after the tiling is completed; (6) After curing, demold to obtain a large-sized thin-walled composite material shell with an Ω-shaped cross section.

2. The manufacturing process for a large-size thin-walled composite material shell with an Ω-shaped cross-section according to claim 1, characterized in that: The male mold protrusion and the base plate frame are integrally formed.

3. The manufacturing process for a large-size thin-walled composite material shell with an Ω-shaped cross-section according to claim 1, characterized in that: The base frame is symmetrically equipped with lifting rings on its outer edge.

4. The manufacturing process for a large-size thin-walled composite material shell with an Ω-shaped cross-section according to claim 1, characterized in that: Several weight-reduction holes are provided on the side wall of the base plate frame.

5. The manufacturing process for a large-size thin-walled composite material shell with an Ω-shaped cross-section according to claim 1, characterized in that: Before laying the prepreg, apply a release agent to the surface of the base frame and the surface of the male mold protrusion.

6. The manufacturing process for a large-size thin-walled composite material shell with an Ω-shaped cross-section according to claim 1, characterized in that: The curing process includes: pressurizing at room temperature to 0.3 MPa, first heating to 160℃ and holding for 1 hour, then pressurizing to 0.6 MPa, followed by holding at 180℃ for 2 hours, 200℃ for 2 hours, and 230℃ for 2 hours in sequence.

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