Integrated forming control method for composite material bearing cylinders with different thicknesses

Abstract

The invention discloses an integrated forming control method for composite material bearing cylinders with different thicknesses, which comprises the following steps: dividing a cylinder main body laying area and a flange reinforcing laying area according to structural characteristics, and setting a target thickness; performing basic layer laying on the forming supporting structure to form a main body pre-forming layer; progressive local reinforced layering is only carried out in a flange reinforced layering area; carrying out integral closed layer laying to form a continuous integrated layer laying structure; a sectional type pressure equalizing structure is arranged on the outer surface of the workpiece, and an expansion compensation gap is reserved; and pressure curing is completed in the same curing period. Compared with the prior art, the forming consistency and the percent of pass are improved through partition progressive laying and compression coordination, and the method is suitable for the composite material bearing cylinder of the rocket instrument cabin.

Description

Technical Field

[0001] This invention relates to the field of composite material molding and manufacturing technology, and in particular to an integrated molding control method for composite material load-bearing cylinders with inconsistent thickness. Background Technology

[0002] Composite material load-bearing tubes are critical load-bearing components in rocket instrument compartments, typically consisting of a main tube body and upper and lower flange structures integrally connected to the main tube body. To meet satellite installation and load-bearing requirements, the structural thickness of the flange area is usually significantly greater than that of the main tube body, resulting in an overall structure with inconsistent thickness.

[0003] In existing technologies, such load-bearing cylinders are mostly manufactured using compression molding or fiber winding. Compression molding relies on a complex, high-precision integral mold, resulting in high manufacturing costs and strict requirements for the consistency of prepreg thickness. Fiber winding is difficult to control in terms of process parameters when dealing with significant differences in thickness between the flange and the cylinder, leading to poor molding consistency.

[0004] In the above molding method, due to the significant thickness difference between the main body of the cylinder and the flange area within the same curing cycle, the response characteristics of different areas during pressurization, resin flow and curing shrinkage are different, which can easily lead to defects such as resin enrichment, dry spots or internal stress concentration in the transition area, thereby reducing the pass rate of non-destructive testing and the consistency of mechanical properties of the parts.

[0005] Therefore, there is still a need in the field for a control method that can achieve stable integrated molding of composite load-bearing cylinders with inconsistent thicknesses within the same curing cycle. Summary of the Invention

[0006] The purpose of this invention is to provide an integrated molding control method for composite material load-bearing cylinders with inconsistent thickness. By systematically controlling the division of the layup area, the layup sequence, and the pressure coordination method, the stable integrated molding of the cylinder body and the flange structure can be achieved within the same curing cycle, thereby improving the consistency of part quality and the molding qualification rate.

[0007] To achieve the above objectives, the present invention adopts the following technical solution: A method for integrated molding control of a composite material load-bearing cylinder with inconsistent thickness includes the following steps: a) Based on the structural characteristics of the load-bearing cylinder, the component is divided into a cylinder body plywood area and a flange reinforcement plywood area along the axial direction, and target thicknesses are set for each area, wherein the target thickness of the flange reinforcement plywood area is greater than the target thickness of the cylinder body plywood area. b) First, lay the basic layer in the main ply area of ​​the cylinder on the forming support structure to form the main preformed layer with initial load-bearing capacity; c) After the main preformed layer is formed, progressive local reinforcement layup is carried out only in the flange reinforcement layup area to gradually build a flange structure with a thickness greater than that of the main body of the cylinder; d) After the flange reinforcement layup is completed, the main body layup area and the flange reinforcement layup area are closed as a whole to form a continuous integrated layup structure; e) Set a segmented pressure equalization structure on the outer surface of the part after the layup is completed, and reserve an expansion compensation gap between adjacent pressure equalization structures to coordinate the pressure state of different thickness areas during the pressure curing process. f) Place the completed ply and pressure equalization structure of the part in a pressure curing environment and complete the pressure curing within the same curing cycle to achieve integrated molding of composite material load-bearing cylinders with inconsistent thickness.

[0008] Preferably, the thickness of the main preform layer is 40% to 70% of the target thickness of the main body layup area of ​​the cylinder.

[0009] Preferably, the progressive local reinforcement layup in the flange reinforcement layup area is a multi-layup, with intermediate compaction treatment performed after each layup.

[0010] Preferably, the overall closed layup is a continuous layup covering the entire part.

[0011] Preferably, the segmented pressure equalization structure includes multiple independent pressure equalization plate segments, which are distributed along the axial direction of the workpiece or along the circumferential direction of the workpiece.

[0012] Preferably, the width of the expansion compensation gap between adjacent pressure equalization plate sections is 1 to 1.5 mm.

[0013] Preferably, the target thickness of the main body ply layer is 2-4 mm, and the target thickness of the flange reinforcement ply layer is 4-8 mm.

[0014] Preferably, the composite material is a carbon fiber reinforced epoxy resin matrix composite material.

[0015] Preferably, the forming support structure is a combined mold formed by detachably connecting multiple mold segments, wherein the mold segments correspond to the main body layup area of ​​the cylinder and the flange reinforcement layup area, respectively.

[0016] Preferably, after pressure curing, the parts can be further machined and quality inspected to obtain finished products that meet design requirements.

[0017] Compared with the prior art, the beneficial effects of the present invention are: By adopting a zoned progressive layup sequence of "main body preforming - flange progressive reinforcement - overall closure", the risk of internal stress concentration caused by thickness differences is significantly reduced. By using a segmented pressure equalization structure and reserved expansion compensation gaps, the pressure coordination of different thickness areas during the pressure curing process is achieved, reducing defects such as resin enrichment and dry spots. This method has low requirements for molds and materials, strong process adaptability, high molding consistency and pass rate, and is suitable for stable integrated molding of composite material load-bearing cylinders with inconsistent thickness. Attached Figure Description

[0018] To illustrate the technical solutions in the embodiments of the present invention or the prior art more specifically and intuitively, the accompanying drawings used in the description of the embodiments or the prior art will be briefly introduced below.

[0019] Figure 1 Schematic diagram of the finished composite material load-bearing cylinder used in rocket instrument compartments; Figure 2 Schematic diagram of load-bearing tube pavement area division; Figure 3 Schematic diagram of the combined molding support structure (mold); Figure 4 Schematic diagram of segmented pressure equalization plate laying. Detailed Implementation

[0020] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.

[0021] Example 1 (Preferred Implementation) The target thickness of the main body of the load-bearing cylinder is 3mm, and the target thickness of the upper and lower flanges is 5mm. The material used is epoxy resin-based carbon fiber woven fabric prepreg.

[0022] First, divide the ply area according to the structural design (e.g., Figure 2 As shown), and design the corresponding combined molding support structure (such as...). Figure 3 (As shown).

[0023] On the combined molding support structure, the overall foundation layer of the main body area of ​​the cylinder is laid first. After every two layers, vacuum-assisted method is used to remove air bubbles between layers until the thickness of the main pre-formed layer is about 1.5mm (accounting for 50% of the target thickness of the main body of the cylinder).

[0024] Subsequently, only the upper and lower flange reinforcement areas are reinforced with localized progressive layers, and vacuum-assisted degassing is performed after every two layers.

[0025] After the flange reinforcement is completed, continue with the overall closed-loop layering covering the entire area until the thickness of the main body area reaches 3mm and the thickness of the flange area reaches 5mm.

[0026] After the layup is completed, a segmented pressure equalization plate (such as...) is laid on the outer surface of the part. Figure 4 As shown in the figure, a 1-1.5mm expansion compensation gap is reserved between adjacent equalizing plates, and then high-temperature resistant vacuum auxiliary material is laid.

[0027] The part is placed in an autoclave and cured under high temperature and high pressure within the same curing cycle.

[0028] After curing, demold and perform CNC machining (e.g.) Figure 1 (The finished product shown). Non-destructive testing using the pulse-echo method revealed uniform internal quality, meeting the Class A requirements of GJB 2895-1997.

[0029] Example 2 (Thickness Ratio Variation) In another embodiment, the target thickness of the main body of the load-bearing cylinder is 2.5 mm, and the target thickness of the flange reinforcement layer is 6 mm.

[0030] During the molding process, a basic layup is first performed on the main body plywood area of ​​the cylinder, forming a pre-formed layer with a thickness of approximately 1.2 mm (accounting for approximately 48% of the target thickness of the main body of the cylinder). Subsequently, progressive local reinforcement layups are performed only in the flange reinforcement plywood area to gradually construct the flange structure. After the flange reinforcement plywood is completed, an overall closed plywood is performed covering both the main body plywood area and the flange reinforcement plywood area to form a continuous, integrated plywood structure.

[0031] The segmented pressure equalization structure setup and pressure curing steps are the same as in Example 1.

[0032] After curing, the parts were machined and tested without damage. The parts had a complete structure, no obvious resin enrichment or dry spot defects in the transition area, and good consistency in mechanical properties.

[0033] This embodiment demonstrates that the method of the present invention is applicable to structures with inconsistent thicknesses and different thickness ratios.

[0034] Example 3 (Change in the arrangement of the pressure equalization structure) In another embodiment, the same thickness design and layup sequence as in Embodiment 1 are used, but the arrangement of the segmented pressure equalization structure is different: the pressure equalization plate segments are mainly distributed along the circumference of the load-bearing cylinder to form multiple independent annular pressure equalization plate segments, and an expansion compensation gap of about 1.2 mm is reserved between adjacent pressure equalization plate segments.

[0035] This arrangement allows for better independent coordination of the compressive deformation at different circumferential positions during the pressure curing process, further improving the consistency of circumferential thickness.

[0036] The remaining steps are the same as in Example 1. Post-molding testing showed that the part exhibited excellent structural and performance uniformity across all circumferential cross-sections.

[0037] This embodiment demonstrates that the present invention has good adaptability to the distribution of pressure equalization plate sections.

[0038] Example 4 (Materials System and Curing Environment Adaptability) In another embodiment, carbon fiber reinforced epoxy resin matrix composite prepregs with different resin systems are selected, while the remaining thickness design and layup sequence are the same as in Embodiment 1.

[0039] After the layup and segmented pressure equalization structure are set up, the part is placed in a pressure curing environment for curing. The curing temperature and pressure profiles are adjusted appropriately according to the characteristics of the selected resin system, but the layup zoning sequence, overall closed layup, and pressure coordination method remain unchanged.

[0040] After molding and testing, the parts also achieved integrated molding of structures with inconsistent thickness, with uniform internal quality, meeting the design requirements.

[0041] This embodiment demonstrates that the method of the present invention has good applicability to different resin systems and does not depend on specific material formulations.

[0042] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A method for integrated molding control of a composite material load-bearing cylinder with inconsistent thickness, characterized in that, Includes the following steps: a) Based on the structural characteristics of the load-bearing cylinder, the component is divided into the main cylinder ply area and the flange reinforcement ply area along the axial direction, and target thicknesses are set for each, wherein the target thickness of the flange reinforcement ply area is greater than the target thickness of the main cylinder ply area. b) First, lay the basic layer in the main ply area of ​​the cylinder on the forming support structure to form the main preformed layer with initial load-bearing capacity; c) After the main preformed layer is formed, progressive local reinforcement layup is carried out only in the flange reinforcement layup area to gradually build a flange structure with a thickness greater than that of the main body of the cylinder; d) After the flange reinforcement layup is completed, the main body layup area and the flange reinforcement layup area are closed as a whole to form a continuous integrated layup structure; e) Set a segmented pressure equalization structure on the outer surface of the part after the layup is completed, and reserve an expansion compensation gap between adjacent pressure equalization structures to coordinate the pressure state of different thickness areas during the pressure curing process. f) Place the completed ply and pressure equalization structure of the part in a pressure curing environment and complete the pressure curing within the same curing cycle to achieve integrated molding of composite material load-bearing cylinders with inconsistent thickness.

2. The molding control method according to claim 1, characterized in that, The thickness of the main preform layer is 40% to 70% of the target thickness of the main body layup area of ​​the cylinder.

3. The molding control method according to claim 1, characterized in that, The progressive local reinforcement layup in the flange reinforcement layup area consists of multiple layups, with intermediate compaction performed after each layup.

4. The molding control method according to claim 1, characterized in that, The overall closed layup is a continuous layup that covers the entire part.

5. The molding control method according to claim 1, characterized in that, The segmented pressure equalization structure includes multiple independent pressure equalization plate segments, which are distributed along the axial direction of the workpiece or along the circumferential direction of the workpiece.

6. The molding control method according to claim 5, characterized in that, The width of the expansion compensation gap between adjacent pressure equalization plate sections is 1 to 1.5 mm.

7. The molding control method according to claim 1, characterized in that, The target thickness of the main body ply layer is 2-4 mm, and the target thickness of the flange reinforcement ply layer is 4-8 mm.

8. The molding control method according to claim 1, characterized in that, The composite material is a carbon fiber reinforced epoxy resin matrix composite material.

9. The molding control method according to claim 1, characterized in that, The forming support structure is a combined mold formed by detachably connecting multiple mold segments, each mold segment corresponding to the main body layup area of ​​the cylinder and the flange reinforcement layup area.

10. The molding control method according to any one of claims 1 to 9, characterized in that, After pressure curing, the parts can be further machined and quality inspected to obtain finished products that meet design requirements.

Images