CN115246234A - Sectional integrated manufacturing method for thermoplastic composite material cabin - Google Patents

Abstract

The invention provides a sectional integrated manufacturing method of a thermoplastic composite cabin section, belonging to the technical field of aircraft cabin sections and comprising the following steps: carrying out sectional molding design on the cabin section structure; forming a plurality of thermoplastic composite material wall plates in batches by using a forming die; and welding the wall plates into the cabin section by adopting a thermoplastic composite welding technology. The method for sectional molding and reassembling of the cabin section solves the problems of high manufacturing cost, high requirements on molds, high requirements on equipment, high processing difficulty and the like of the cabin section in the prior art. Taking a cabin section with the diameter of 800mm as an example, the design of forming and assembling by 6 sections is adopted, each section of structure is formed and assembled respectively, the chord length size of each section of structure is 400mm, the half is reduced, the requirements on equipment such as a forming die, an autoclave and the like are reduced, and therefore the manufacturing cost and the processing difficulty are reduced.

Description

Sectional integrated manufacturing method for thermoplastic composite material cabin

Technical Field

The invention belongs to the technical field of aircraft cabin sections, and particularly relates to a segmented integrated manufacturing method of a thermoplastic composite cabin section.

Background

The cabin-class structural components are key components of strategic tactical missiles, rockets, aerospace aircrafts and hypersonic aircrafts. In the manufacturing process of the aircraft, the requirements for lightening the structural quality, saving the economic cost and ensuring the safety performance of the product are higher and higher. The light alloy or high-strength resin-based composite material is adopted to replace steel, so that the structural quality can be reduced while the structural strength, toughness, fatigue resistance and the like are met. The resin-based carbon fiber composite material is an advanced lightweight material which is most applied in the field of aerospace at present, and can be divided into thermosetting and thermoplastic composite materials according to different resin matrix materials. The two materials correspond to different molding processes, and both the two processes can realize low-cost processing and manufacturing.

In comparison, the thermosetting composite material product has advantages in process maturity, and the current lightweight high-performance composite material cabin section also mainly adopts carbon fiber reinforced thermosetting resin-based composite materials. Thermoplastic composite materials represent the future technical development trend, have lower density, higher mechanical properties (such as specific strength, specific rigidity, impact resistance and the like), good maintainability and recycling performance, become one of the rapidly-developed emerging materials, and are gradually and widely applied in a plurality of fields.

The biggest hurdles to the spread of carbon fiber composites in aerospace structures are high cost and long manufacturing cycle time. For example, the composite material structure commonly used in aerospace at present is mainly a grid reinforced structure. Such as falcon9, XX-7 fairing, etc., not only requires large molds to match the size of the product, but also requires autoclave equipment with higher energy consumption than the product to cure. The structural product has high processing and production cost, and the production process is of a string type, so that the production period is longer. If the diameter of the future carrying aircraft reaches 10 meters, the problems of high manufacturing cost, high mold requirement, high equipment requirement, high processing difficulty and the like are more obvious for the size level.

Disclosure of Invention

In view of the above, the present invention is directed to a method for manufacturing a thermoplastic composite cabin by segmented integration, so as to alleviate the above technical problems.

In order to achieve the purpose, the technical scheme of the invention is realized as follows:

a segmented integrated manufacturing method for a thermoplastic composite cabin section comprises the following steps:

s1, carrying out sectional molding design on a cabin section structure;

s2, forming a plurality of thermoplastic composite material wall plates in batches by using a forming die;

and S3, welding the plurality of wall plates into cabin sections by adopting a thermoplastic composite material welding technology.

The panels may be mechanically connected by bolts, but welding is the preferred material for the present invention.

Further, between steps S2 and S3, further comprising:

s4, manufacturing thermoplastic composite material ribs by adopting continuous die pressing equipment;

and S5, welding the ribs and the inner side of the wall plate by adopting a thermoplastic composite material welding technology.

Further, after step S3, the method further includes:

s6, winding the continuous fiber prepreg outside the cabin section and curing in situ.

Further, the thermoplastic composite material is carbon fiber polyether ether ketone or polyether ketone polyarylether ketone.

Further, the thermoplastic composite welding technique may be resistance welding, inductive welding, or ultrasonic welding.

Compared with the prior art, the segmented integrated manufacturing method for the thermoplastic composite cabin section has the following advantages:

1. the method for sectional molding and reassembling of the cabin section solves the problems of high manufacturing cost, high requirements on molds, high requirements on equipment, high processing difficulty and the like of the cabin section in the prior art. Taking a cabin section with the diameter of 800mm as an example, the design of forming and assembling by 6 sections is adopted, each section of structure is formed and assembled respectively, the chord length size of each section of structure is 400mm, the half is reduced, the requirements on equipment such as a forming die, an autoclave and the like are reduced, and therefore the manufacturing cost and the processing difficulty are reduced.

2. The segmented wall plate structure can be formed by paving and pasting a single mould, and can also be prepared by adopting a continuous compression molding technology, so that a high-energy-consumption autoclave is avoided, the cost is greatly reduced, and if the wall plate prepared by adopting the continuous compression molding technology is adopted, the segmented wall plate structure has the characteristics of good forming quality and good consistency.

3. Before the process of assembling the cabin section structure in a split mode, part of the cabin interior instruments and equipment can be deployed, installed and debugged in advance, opening windowing on a subsequent cabin section structure is avoided, convenience of equipment installation is possibly brought, and the period of assembling the whole structure is shortened.

4. In the future, the number of the sections of the whole cabin section can be increased and the overall cabin section can be designed into an 8-section structure, a 12-section structure, an 18-section structure and the like. The whole cabin section structure is split into a plurality of narrow and small section structures which are welded, and the preparation speed of the cabin section structure is greatly improved. By combining the characteristic that the thermoplastic composite material can be recycled, all cabin sections, sectional materials and ribs can be recycled, disassembled, maintained and reused. The diversity and the splicing property of the profile structure; the modular design advantage of the deck section structure will play a role, bringing a new revolution in the advanced composite manufacturing industry.

Drawings

The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate an embodiment of the invention and, together with the description, serve to explain the invention and not to limit the invention. In the drawings:

FIG. 1 is a schematic structural view of a thermoplastic composite deck section according to the present invention.

Description of reference numerals:

1-a wall plate; 2-ribs; 3-welding edges; 4-covering.

Detailed Description

It should be noted that the embodiments and features of the embodiments may be combined with each other without conflict.

In the description of the present invention, it is to be understood that the terms "center", "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", and the like, indicate orientations or positional relationships based on those shown in the drawings, and are used only for convenience in describing the present invention and for simplicity in description, and do not indicate or imply that the referenced devices or elements must have a particular orientation, be constructed and operated in a particular orientation, and thus, are not to be construed as limiting the present invention. Furthermore, the terms "first", "second", etc. are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first," "second," etc. may explicitly or implicitly include one or more of that feature. In the description of the present invention, "a plurality" means two or more unless otherwise specified.

In the description of the present invention, it should be noted that, unless otherwise explicitly specified or limited, the terms "mounted," "connected," and "connected" are to be construed broadly, e.g., as meaning either a fixed connection, a removable connection, or an integral connection; can be mechanically or electrically connected; they may be connected directly or indirectly through intervening media, or may be connected through elements within two elements. The specific meaning of the above terms in the present invention can be understood by those of ordinary skill in the art through specific situations.

The present invention will be described in detail below with reference to the embodiments with reference to the attached drawings.

The invention provides a sectional integrated manufacturing method of a thermoplastic composite cabin section, which adopts thermoplastic composite carbon fiber polyether ether ketone (CF/PEEK) as a base material and firstly carries out sectional molding design on a cabin section structure; then forming a plurality of wall plates in batches by using a forming die, wherein both ends of each wall plate are provided with welding edges, and preparing ribs and stringers by using continuous die pressing equipment, wherein the ribs are not shown in a truss drawing; then welding the ribs, the stringers and the wall plate into a reinforced wall plate structure by adopting a thermoplastic composite welding technology, and further welding the reinforced wall plate structure into a structural cabin section; and finally, winding continuous fiber prepreg outside the structural cabin section and curing in situ to form a skin, so that the circumferential bearing capacity of the cabin section structure is enhanced.

The panels may be mechanically connected by bolts, but welding is the preferred material for the present invention.

Aerospace structures are large and complex and require joining of different components together by joining techniques during manufacture and assembly, and therefore require reliable, automated and economical joining techniques. Welding techniques for thermoplastic composites have a number of advantages. The mainstream welding of thermoplastic composite materials at present is classified into resistance welding, inductive welding and ultrasonic welding.

Resistance welding adopts welding elements such as resistance wires/metal mesh strips and the like to be arranged at a welded interface, the resistance wires/the metal mesh strips are electrified to heat and melt the interface, and the melt welding can be finished through pressure testing. After the welding is completed, a metal mesh strip (about 0.2mm thick) remains in the weld face. The arrangement of the resistance wire/metal mesh strip only where needed during welding, i.e. at the junction between the two surfaces, limits the material melt area, reducing the risk of compromising the shape or dimensional stability of the part. In resistance heating welding, an implanted heating element is placed between the surfaces to be welded of two welded parts, and when current flows through the heating element, heat is generated due to the joule effect and transferred to the surrounding joint interface, causing the resin to melt. A weld joint is formed under pressure. The resistance welding process is mature, has strong adaptability, can be automatically produced, and is suitable for welding large-scale structures. In addition, the thermoplastic composite material is fused into a whole after welding, the bonding strength is high, riveting, screwing and the like of the thermosetting composite material can be replaced, the weight is reduced, and the cost is reduced. However, after welding, residues exist at the interface, and improper treatment easily causes phenomena such as stress concentration and electrochemical corrosion at the joint. The electric resistance welding has the technical characteristics of simple and flexible equipment, short process flow, no need of surface treatment, low cost, simple process flow, high joint strength and the like. The performances of resistance welding and compression molding APC-2 are compared, the lap joint shear strength of the resistance welding test piece is almost the same as that of the compression molding test piece, but the processing time is much shorter. Using a PEEK film, the maximum lap shear strength of resistance welding APC-2 is 44.8MPa but fiber slippage exists in the joint; the maximum lap shear strength of the APC-2/PEI resistance welding test piece was 35.9MPa with no fiber slippage. After the APC-2/PEI is subjected to a constant temperature process (20min, 293 ℃), the base line of the lap shear strength is 43.6MPa, and meanwhile, the quality of a welding joint can be monitored in real time by matching with ultrasonic imaging equipment to perform repair welding in time.

Induction welding is a special welding process in which an induction coil generates a high frequency electromagnetic field, and a welding induction material placed at a welding interface generates eddy currents and generates heat, so that the interface is melted, and the purpose of welding is achieved under the action of pressure. Induction welding is particularly useful for welding carbon fiber reinforced thermoplastic composite structural members. Because the carbon fiber can be conductive, eddy current can be generated through the induction coil to generate heat, extra induction materials do not need to be introduced when the carbon fiber reinforced composite material is welded, only carbon fiber fabric prepreg is adopted to be laid and pasted on one side of a welded interface, if the carbon fiber reinforced composite material is non-conductive, a conductive net can be placed on the interface, and the carbon fiber reinforced composite material can be carbon fiber or metal net. The induction welding has the advantages that the induction coil does not directly contact with an induction material, and a non-induction area does not generate heat, so that after the parameters are reasonably set, the welding is more accurate, the deformation and the redundant resin flow are not easy to generate, in addition, the induction welding efficiency is higher, the continuous welding can be realized, and the induction welding is suitable for long welding seams and can weld irregular and complex structures. The induction welding is also a welding technology with less human factor intervention, has higher reliability and is easy to realize automatic production. Whether the temperature distribution on the welding surface is uniform or not is one of the most important factors affecting the connection performance in induction welding, and depends mainly on the shape of the implanted induction element and the design of the induction coil. Induction welding has the disadvantages that the implant material is not easy to manufacture and the introduction of the welding induction element directly affects the strength and electrical performance of the joint. At present, the research of induction welding is mainly in the aspects of the influence rule of carbon fibers in composite materials on the distribution of a welding surface temperature field, the reliability of a welding joint and the like. The induction welding has the advantages of short welding time, capability of being applied to any complex component with a regular surface, capability of simultaneously welding a plurality of large-scale parts or multiple welding surfaces and high reliability of induction welding thermoplastic materials. The main advantage of induction welding is that a continuous weld joint can be obtained by moving the coil along the joint. Another advantage of induction is that the components can be disassembled along the weld by reheating, thereby enabling repair of weld defects. The joint strength of induction welding is high, for example, an APC-2 prepreg tape and a PEEK adhesive film without metal additives are used on an interface, and the lap joint shear strength of certain PEEK, DPS and PEI carbon reinforced composite materials can reach 38.5-48.3 MPa.

Ultrasonic welding generally adopts high-frequency mechanical wave vibration welding interface above 20kHz, so that heat is generated among molecular chains on the surface of thermoplastic materials to melt the interface, and ultrasonic welding can be completed under the condition of applying pressure. The heat conductivity of the high-performance carbon fiber reinforced thermoplastic composite material is greatly higher than that of pure resin, and PEEK is mostly a semi-crystalline material, so that the heat generating capacity of the material in an ultrasonic field is greatly reduced when the material exceeds a melting point, and the material is more easily solidified before being spread after a molten film is generated, thereby influencing the welding quality. The ultrasonic welding speed is high, the period is short, but the welding area is small, so that the ultrasonic welding method is not suitable for welding long welding seams, and spot welding is more applied. In addition, the advanced ultrasonic welding equipment can comprehensively control and monitor the welding process, so that the welding process is easy to realize automation, and the method is particularly suitable for batch production. At present, the research direction of ultrasonic welding is to obtain a high-strength joint by optimizing the shape of an energy guiding rib; the joint quality is improved by controlling the amplitude and the pressure in real time; the dual-frequency ultrasonic welding machine is adopted to improve the heat generation efficiency at the welding interface, shorten the welding time, lighten the welding connection mode of ultrasonic waves on the damaged ribs and the cabin section of the composite material, usually finish the welding within a few minutes, do not need large-scale equipment for curing and accelerate the assembly process; meanwhile, the connection mode avoids the complex mold design process and the forming and paving process required by the integral forming of the rib cabin section, and effectively reduces the use of fasteners.

In the preparation of the whole reinforced wall plate cabin section structure, the winding of the shell of the cabin section structure is an optional structure. The extra winding shell ensures the circumferential fiber continuity and enhances the bearing capacity of the structure. The winding technology of the thermoplastic composite material uses in-situ curing, avoids using a high-energy-consumption autoclave for forming and curing, and has a great effect on reducing the forming cost. Through the welding of each part of the cabin section, the cabin section body becomes a core mold for winding the shell, and demolding is not needed after the forming, so that the complexity of the whole preparation process is reduced.

Many large companies and research institutions have achieved certain results in equipment and process research for thermoplastic composite winding. The technology has been applied in several areas in the European and American countries, such as the Netherlands, france, where thermoplastic composites are used for winding wind turbine blades; the European composite material research and development center uses a thermoplastic composite material laying and winding technology to manufacture an aerospace engine; aircraft parts and the like are made in the united states using thermoplastic winding technology.

At present, the research on the winding technology of the thermoplastic composite material abroad is relatively deep, a plurality of research organizations and enterprises research mature high-performance thermoplastic winding equipment, and certain achievements on the aspects of heating, tension, curing and forming and the like are achieved. In recent years, studies on this aspect have been carried out in China, but many studies on glass fiber/polypropylene composite materials have been focused, and studies on high-strength carbon fiber reinforced resin-based composite materials have been relatively rare, and studies on heating, tension control, and pressure curing have been relatively rare.

At present, the winding equipment for thermoplastic composite materials in China mainly considers wet method and dry method winding equipment. The winding of thermoplastic materials requires higher heating temperature than thermosetting materials, which puts higher requirements on the heating capacity of winding equipment, and the heating temperature is an important process parameter for thermoplastic winding forming, the interlayer bonding effect of the materials, and the resin crystallinity and the winding efficiency are closely related to the temperature of the materials in the winding process, so that a proper heating mode needs to be researched, the influence rule of the temperature on the quality of a product is researched, and the coupling effect of the temperature and other process parameters is researched.

In the aspect of tension control, the main difference between the winding of the thermoplastic composite material and the winding of wet-process fibers lies in the difference of feeding modes, the wet-process winding adopts the winding of yarn balls, the winding of the thermoplastic material adopts the winding of prepreg silk trays, the radius change of the yarn balls in the winding process is slow, the change of the rotational inertia of the yarn balls is small, and when the linear speed of the fibers is stable, namely the fibers Zhang Liwen are timed, the rotating speed of a motor for controlling the movement of the yarn balls is stable; the thermoplastic material is wound by using the prepreg tray, the width of the tray is only one bandwidth, the radius of the tray is changed quickly in the winding process, the change of the rotational inertia is large, the winding linear speed of the prepreg is required to be kept stable, and the rotating speed of a motor for controlling the rotation of the tray needs to be adjusted quickly according to the change of the radius of the tray, so that the stability of the tension is kept. Therefore, the mechanism and method for controlling the tension of the thermoplastic composite material need to be further researched to adapt to the winding and forming of the thermoplastic prepreg.

The thermoplastic winding uses prepreg filaments or prepreg tapes made of composite materials, different from wet fiber winding, the prepreg filaments can generate an elastic edge phenomenon in the process of winding an inextensible curved surface to cause wrinkles, and the winding track of the prepreg filaments needs to be designed to avoid the deformation of the prepreg filaments and improve the quality of products.

Designing a structural cabin section in a segmented manner: the cabin sections are assembled by 6-lobe structures, the sizes of the cabin sections can be selected and designed according to practical application, and the diameters of the assembled cabin sections are not less than phi 0.8m and not more than phi 12m. 1 set of matched forming die and 1 set of matched assembling tool are prepared. The length of the cabin section is not less than 0.5m. Preparing and molding the thermoplastic section: the continuous molding apparatus is provided in a batch state. The thickness of the continuous fiber thermoplastic sheet/section bar of CF/PEEK and other high performance is controllable from 1 mm to 30mm, the fiber content is more than 60%, the porosity is less than 1%, the distribution form of the laying layer and the fabric (including typical 0 degree, 90 degree, 45 degree unidirectional prepreg, fabric prepreg and the like) can be freely set, the production speed is more than 30m/h, and the yield is more than 98%. Thermoplastic welding: the continuous welding speed is higher than 0.6m/min, the welding strength of single lap joint and skin ribs is higher than 35MPa, and the discrete variation coefficient of strength distribution is less than 10%. Winding and forming: the winding speed of the thermoplastic composite material dry-method winding equipment is not lower than 6r/min, and meanwhile, the optimal forming process parameters of the winding speed, the winding tension and the heating temperature are groped by combining the product test result.

The application scenes of the structural form of the segmented integrated reinforced wall plate include the structures of various cabin sections of national defense strategic tactical missiles, space launch vehicle cabin sections, stage sections, manned spacecraft cabin sections, unmanned aerial vehicle fuselage cabin sections and the like.

The present invention is not limited to the above preferred embodiments, and any modifications, equivalent substitutions, improvements, etc. within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims (7)

1. A segmented integrated manufacturing method for a thermoplastic composite cabin section is characterized by comprising the following steps:

carrying out sectional molding design on the cabin section structure;

forming a plurality of thermoplastic composite material wall plates in batches by using a forming die;

and welding the wall plates into the cabin section by adopting a thermoplastic composite welding technology.

2. The segmented integrated manufacturing method for a thermoplastic composite cabin according to claim 1, wherein between the step of batch-forming a plurality of thermoplastic composite wall panels with a forming mold and the step of welding the plurality of wall panels into the cabin with a thermoplastic composite welding technique further comprises:

manufacturing thermoplastic composite material ribs by adopting continuous die pressing equipment;

and welding the ribs with the inner side of the wall plate by adopting a thermoplastic composite material welding technology.

3. The method of claim 1, wherein the step of welding the plurality of wall panels into the deck section using thermoplastic composite welding techniques further comprises, after the step of:

and winding continuous fiber prepreg outside the cabin section and curing in situ.

4. The method of claim 1, wherein the step of manufacturing the thermoplastic composite deck section comprises: the thermoplastic composite material is carbon fiber polyether ether ketone or polyether ketone polyarylether ketone.

5. The method of claim 1, wherein the step of manufacturing the thermoplastic composite deck section comprises: the thermoplastic composite material welding technology is resistance welding.

6. The method of claim 1, wherein the step of manufacturing the thermoplastic composite deck section comprises: the thermoplastic composite welding technology is inductive welding.

7. The method of claim 1, wherein the step of manufacturing the thermoplastic composite deck section comprises: the thermoplastic composite welding technology is ultrasonic welding.

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