Composite material cylindrical product and forming method thereof

Abstract

The present invention relates to the technical field of non-metallic composite material manufacturing, and particularly relates to a composite cylindrical part and a forming method thereof. The cylindrical part is sequentially provided with a heat-insulating layer, a first transition buffer structure, an inner side wall plate, a radial filling structure and an outer side wall plate from the inside to the outside; a first transition buffer structure for fixedly connecting the heat-insulating layer and the inner side wall plate is arranged between the heat-insulating layer and the inner side wall plate, wherein the difference in expansion coefficients between the heat-insulating layer and the inner side wall plate is 8×10-6 m / °C to 9×10-6 m / °C; the first transition buffer structure is a multi-layer composite structure and is provided with a toughness support layer matching the heat-insulating layer and the inner side wall plate. Compared with the prior art, the present invention greatly reduces the thermal conductivity, the thermal conductivity drops by 15.4%, and the shear strength is increased by 9.09% to 16.6%; it effectively buffers the damage caused by different thermal expansion rates caused by the temperature difference between the inside and outside of the cylinder, and greatly improves the service life; during the process forming, a conformal rubber treatment is added to the fillet of the outer side wall plate, which solves the problem of easy glue accumulation and further reduces the total weight.

Description

Technical Field

[0001] The invention relates to the technical field of non-metal composite material manufacturing, and in particular to a composite material cylindrical product and a molding method thereof. Background Art

[0002] Cylindrical parts are often used as launching tube components for fireworks and civilian shooting equipment. The launching tube components must meet the structural and functional requirements as well as the requirements of high strength at high temperatures, light weight and portability. In traditional technologies, metal structure cylinders have problems such as heavy weight, welding deformation, and easy rust. Existing composite launch tubes have poor rigidity, large weight and volume, poor heat insulation, easy cracking of materials between different layers, short life, non-reusability, and difficulty in balancing heat insulation and volume.

[0003] Therefore, there is an urgent need to develop a set of lightweight launch tubes with good high-temperature mechanical strength, good thermal insulation performance and long service life. Summary of the invention

[0004] In view of the above analysis, the present invention aims to provide a composite tubular product and a molding method thereof, so as to solve at least one of the technical problems of low high-temperature mechanical strength, poor thermal insulation performance and short service life existing in existing tubular products such as launching components in launching tubes.

[0005] The purpose of the present invention is mainly achieved through the following technical solutions:

[0006] The present invention provides a composite material cylindrical product comprising a heat-insulating layer, a first transition buffer structure, an inner wall plate, a radial filling structure and an outer wall plate which are arranged in sequence from the inside to the outside;

[0007] The first transition buffer structure is a multi-layer composite structure including a tough support layer, and the tough support layer can match the anti-insulation layer and the inner wall plate with different thermal expansion coefficients.

[0008] Preferably, the difference in thermal expansion coefficient between the heat-insulating layer and the inner wall plate is 8×10 -6 m / ℃~9×10 -6 m / ℃.

[0009] Preferably, the first transition buffer structure comprises a first rigid connection layer, a first toughness support layer and a second rigid connection layer which are sequentially distributed from the high temperature zone to the low temperature zone.

[0010] Preferably, the first rigid connection layer is a glass fiber felt layer, the first toughness support layer is a glass fiber cloth layer, and the second rigid connection layer is a glass fiber felt layer.

[0011] Preferably, the first rigid connection layer has 2 to 3 glass fiber felt layers, the first toughness support layer has 1 to 3 glass fiber cloth layers, and the second rigid connection layer has 2 to 3 glass fiber felt layers.

[0012] Preferably, the glass fiber mat of the first rigid connection layer and the second rigid connection layer has a fiber length of 2 mm to 10 mm; the glass fiber mat is chopped strands; the glass fiber cloth is any one of woven cloth, twill cloth and plain cloth; the density of the glass fiber cloth is 170 g / cm 3 ~220g / cm 3 Twill.

[0013] Preferably, the anti-heat-insulating layer adopts a fiber-reinforced resin matrix structure.

[0014] Preferably, the matrix resin of the fiber-reinforced resin matrix structure is one or more of phenolic resin, silicone resin, silicon-containing aromatic acetylene resin, aryl acetylene resin or modified resins of phenolic resin, silicone resin, silicon-containing aromatic acetylene resin and aryl acetylene resin.

[0015] Preferably, the matrix resin of the fiber-reinforced resin matrix structure is an interpenetrating composite material modified phenolic resin.

[0016] Preferably, the tubular component is further provided with an axial support structure parallel to the axial direction of the tubular component, and the axial support structure is placed inside the radial filling structure and fixed to the outer wall of the inner wall plate.

[0017] Preferably, the axial support structures are multiple and spaced apart along the circumference of the cylindrical workpiece.

[0018] Preferably, the axial support structure includes an internal filling structure and an external reinforcement structure surrounding the internal filling structure; the external reinforcement structure includes a panel fixedly connected to the inner wall panel and reinforcing ribs surrounding and fixing the internal filling structure.

[0019] Preferably, the panel and the reinforcing ribs are fiber reinforced resin matrix structures.

[0020] Preferably, the fiber-reinforced structural layer in the axial support structure is quasi-isotropic; the reinforcing fibers of the fiber-reinforced structural layer are one or more of quartz fibers, carbon fibers, high-silica fibers, and basalt fibers.

[0021] Preferably, the reinforcing fibers of the fiber-reinforced resin matrix structure are carbon fibers.

[0022] Preferably, the matrix resin of the fiber-reinforced resin matrix structure is one or more of phenolic resin, silicone resin, silicon-containing aromatic acetylene resin, aromatic acetylene resin and epoxy resin, or modified resins of phenolic resin, silicone resin, silicon-containing aromatic acetylene resin, aromatic acetylene resin and epoxy resin; the internal filling structure is a lightweight material with a hollow microporous or bubble structure.

[0023] Preferably, the internal filling structure is any one of PEI foam and PMI foam; the matrix resin of the fiber reinforced resin matrix structure is EH301 epoxy resin.

[0024] Preferably, the cylindrical component is further provided with a radial support structure, and the radial support structure is arranged between the radial filling structure and the outer side wall plate.

[0025] Preferably, the radial support structures are arranged at intervals along the axial direction of the cylindrical workpiece.

[0026] Preferably, the radial support structure is a lightweight material with a hollow microporous or bubble structure.

[0027] Preferably, the radial support structure is any one of PEI foam or PMI foam.

[0028] Preferably, a second transition buffer structure is further provided between the radial supporting structure, the radial filling structure and the outer wall plate; the radial supporting structure and the outer wall plate are fixedly connected via the second transition buffer structure; the radial filling structure and the outer wall plate are fixedly connected via the second transition buffer structure; the second transition buffer structure is a multilayer composite structure including a tough support layer, the tough support layer can match the radial supporting structure and the outer wall plate with different thermal expansion coefficients, and the tough support layer can match the radial filling structure and the outer wall plate with different thermal expansion coefficients.

[0029] Preferably, the difference in thermal expansion coefficient between the radial support structure or the radial filling structure and the outer wall plate is 35×10 -6 m / ℃~41×10 -6 m / ℃.

[0030] Preferably, the second transition buffer structure comprises a third rigid connection layer, a second toughness support layer and a fourth rigid connection layer which are sequentially distributed from the high temperature zone to the low temperature zone.

[0031] Preferably, the third rigid connection layer is a glass fiber felt layer, the second toughness support layer is a glass fiber cloth layer, and the fourth rigid connection layer is a glass fiber felt layer.

[0032] Preferably, the third rigid connection layer has 2 to 3 glass fiber felt layers, the second toughness support layer has 1 to 3 glass fiber cloth layers, and the fourth rigid connection layer has 2 to 3 glass fiber felt layers. layer .

[0033] Preferably, the fiber length of the glass fiber mat of the third rigid connection layer and the fourth rigid connection layer is 10 mm to 15 mm; the glass fiber mat is chopped strands; the glass fiber cloth is any one of woven cloth, twill cloth and plain cloth; the density of the glass fiber cloth is 170 g / cm 3 ~220g / cm 3 Twill.

[0034] Preferably, the anti-heat-insulating layer adopts a fiber-reinforced resin matrix structure.

[0035] Preferably, the matrix resin of the fiber-reinforced resin matrix structure is one or more of phenolic resin, silicone resin, silicon-containing aromatic acetylene resin, aryl acetylene resin or modified resins of phenolic resin, silicone resin, silicon-containing aromatic acetylene resin and aryl acetylene resin.

[0036] Preferably, the matrix resin of the fiber-reinforced resin matrix structure is an interpenetrating composite material modified phenolic resin.

[0037] Preferably, the fiber reinforced resin matrix structure is provided with a fiber reinforced structural layer.

[0038] Preferably, the fiber-reinforced structural layer adopts one or more of the following methods: a fiber woven structural layer, a fiber cloth laminated paving layer, a chopped strand mat layer, a chopped strand mat needle-punched layer, and a fabric laminated needle-punched layer.

[0039] Preferably, the reinforcing fibers of the fiber-reinforced structural layer are one or more of quartz fibers, carbon fibers, high-silica fibers, and basalt fibers.

[0040] Preferably, the reinforcing fibers of the fiber-reinforced resin matrix structure are quartz fibers, carbon fibers or a mixture of the two.

[0041] Preferably, the inner wall panel and the outer wall panel are fiber-reinforced resin matrix structures, and the fiber-reinforced resin matrix structure is provided with a fiber-reinforced structural layer.

[0042] Preferably, the reinforcing fibers of the fiber-reinforced structural layer are one or more of quartz fibers, carbon fibers, high-silica fibers, and basalt fibers.

[0043] Preferably, the reinforcing fibers of the fiber-reinforced resin matrix structure are carbon fibers.

[0044] Preferably, the matrix resin of the fiber reinforced resin matrix structure is one or more of phenolic resin, silicone resin, silicon-containing aromatic acetylene resin, aromatic acetylene resin and epoxy resin or modified resins of phenolic resin, silicone resin, silicon-containing aromatic acetylene resin, aromatic acetylene resin and epoxy resin.

[0045] Preferably, the matrix resin of the fiber-reinforced resin matrix structure is EH301 epoxy resin.

[0046] Preferably, the radial filling structure is a lightweight material with a hollow microporous or bubble structure.

[0047] Preferably, the radial filling structure is any one of PEI foam or PMI foam.

[0048] The present invention provides a method for forming a composite material cylindrical product, comprising the following steps:

[0049] Step 1: Dip-molding of heat-insulating layer:

[0050] The anti-insulation layer is prepared in the mold using a vacuum impregnation process;

[0051] Step 2: Lay the first transition buffer structure:

[0052] Laying the materials of the first transition buffer structure layer by layer with the outer surface of the heat-insulating layer as the reference surface;

[0053] Step 3: Vacuum inlet molding of the inner wall panel:

[0054] Using the outer surface of the first transition buffer structure as a reference surface, a vacuum introduction process is used to prepare a cylindrical component preform with an inner wall plate fixed on the outside;

[0055] Step 4: Axial support structure forming:

[0056] The axial support structure is prepared in the mold using the autoclave process;

[0057] Step 5: Assemble the inner wall panel and the axial support structure:

[0058] The axial support structure is fixedly connected at a preset position of the inner wall plate to obtain a cylindrical component preform covered with the axial support structure;

[0059] Step 6: Fix the radial filling structure and radial support structure:

[0060] The radial filling structure is bonded and fixed to the outer wall of the cylindrical preform covered with the axial support structure; the radial support structure is bonded and fixed to the outer wall of the radial filling structure, and cured and molded under vacuum to obtain a cylindrical preform having the radial filling structure and the radial support structure;

[0061] Step 7: Lay the second transition buffer structure:

[0062] Laying a second transition buffer structure on the outer wall of the cylindrical part preform having the radial filling structure;

[0063] Step 8 Exterior siding molding:

[0064] The outer wall panel is prepared on the outer wall of the second transition buffer structure by adopting a vacuum introduction process.

[0065] Preferably, in step 1, the vacuum degree during the molding process is ≥980 mbar, the heating temperature is 80° C. to 180° C., and the molding time is 12 h to 24 h.

[0066] Preferably, step 3 comprises the following steps:

[0067] Step 3.1: After the inner wall panel preform is evacuated, it is preheated at 120° C. to 130° C. After the negative pressure operation starts, it is gradually increased in the range of 600 mbar to 980 mbar;

[0068] Step 3.2: preheating the resin at 100° C. to 120° C. and introducing the resin into the preheated inner wall panel preform;

[0069] Step 3.3: heat-treat the inner wall panel preform into which the resin has been introduced at 130° C. to 150° C. and 170° C. to 180° C. in sequence.

[0070] Preferably, step 4 comprises the following steps:

[0071] Step 4.1: Cast the panel of the external reinforcement structure in the mold using fiber prepreg. The fiber prepreg is vacuum compacted once every 3 to 5 layers. The compaction time is 15 to 50 minutes. After the negative pressure operation starts, it gradually increases in the range of 600 mbar to 980 mbar.

[0072] Step 4.2: At the location of the panel internal filling structure, fiber prepreg is laid layer by layer to prepare reinforcing ribs, and pre-compacted by hot compaction at a temperature of 130°C to 140°C for 15min to 50min;

[0073] Step 4.3: Place the preform with the reinforcing ribs 2032 in a vacuum bag in an autoclave, and heat treat the preform in two stages at 130° C. to 150° C. and 170° C. to 180° C. at a pressure of 0.4 MPa to 0.6 MPa.

[0074] Preferably, step 5 includes the following steps: fastening the axial support structure to the cylindrical part preform with the inner wall plate fixed on the outside with a film, and forming it by heat treatment in two stages at 130℃~150℃ and 170℃~180℃ in a negative pressure environment gradually increasing between 600 and 980mbar.

[0075] Preferably, step 6 comprises the following steps:

[0076] Step 6.1: fix the radial filling structure to the outer wall of the inner wall plate of the cylindrical preform covered with the axial support structure, and position and fix the radial support structure on the outer wall of the radial filling structure;

[0077] Step 6.2: The cylindrical preform having the radial filling structure and the radial supporting structure is heat-treated in two stages at 130° C. to 150° C. and 170° C. to 180° C. in a negative pressure environment gradually increasing between 600 and 980 mbar.

[0078] Preferably, in step 8, the outer wall panel is prepared by a vacuum introduction process, which requires sequentially laying a release cloth, an isolation film, a guide net and a vacuum bag on the outer wall of the second transition buffer structure.

[0079] Preferably, a conformable rubber is placed between the vacuum bag and the guide net at the fillet at the connection between the fixed end of the outer wall panel and the radial support structure; and when laying the release cloth at the fillet, two independent release cloths need to be overlapped, and when laying the guide net at the fillet, two independent guide nets need to be overlapped.

[0080] Compared with the prior art, the present invention can achieve at least one of the following beneficial effects:

[0081] (1) The present invention sets a transition buffer structure between the inner wall panel and the heat-insulating layer, such as glass fiber felt + glass fiber cloth + glass fiber felt. Compared with the prior art, the shear strength of the inner wall is increased from 55 MPa to 60 MPa, and the shear strength of the outer wall is increased from 60 MPa to 70 MPa, which are increased by 9.09% and 16.6% respectively.

[0082] (2) The transition buffer structure can adopt the structure of "glass fiber felt + glass fiber cloth + glass fiber felt", in which the glass fiber cloth layer can produce a certain degree of "creep deformation" when subjected to external force. Its flexible structure greatly improves the stress difference and cracking caused by the different thermal expansion coefficients of different materials when the temperature changes, and forms a good stress buffer layer as a whole; a transition buffer structure can also be set at the connection between the radial support structure and the outer wall panel, and the radial support structure and the glass fiber felt adjacent to the outer wall panel are tightly fixed and connected, which can effectively avoid the defects of the glass fiber cloth body with weak strength and poor shear resistance; and thus effectively buffer the stress and deformation caused by the different thermal expansion coefficients of the materials due to the temperature difference between the inside and outside of the inner wall panel, thereby effectively avoiding the cracking and deformation of the inside and outside of the inner wall panel, greatly improving the service life.

[0083] (3) The present invention provides an axial support structure in the axial direction of the cylindrical component and a radial support structure distributed along the circumferential direction. The interior of the axial support structure and the radial support structure are lightweighted, thereby greatly reducing the incidental weight brought by the support structure while improving the structural strength, and has the advantage of being lightweight. At the same time, when processing the heat-insulating layer and the inner and outer wall panels, a vacuum impregnation or vacuum introduction process is adopted, so that the axial support structure and the radial support structure can be arranged on the inner side of the outer wall of the cylindrical component to achieve an integrated appearance. At the same time, when the structure is subjected to external force, it helps to disperse the external force and the force is more balanced, which can reduce the probability of damage to the cylindrical component due to external force.

[0084] (4) The axial support structure, radial support structure and radial filling structure of the present invention can use high temperature resistant PEI or PMI high temperature resistant sponge to achieve lightweight insulation. Even at high temperatures, the PEI or PMI high temperature resistant sponge itself still has good strength.

[0085] (5) When the outer wall panel is formed, the guide net at the connecting fillet of the radial filling structure and the radial supporting structure can be overlapped, and a conformable rubber can be placed between the fillet and the vacuum bag. This can improve the defects of the traditional process that the vacuum bag is difficult to fit at the connecting fillet and the pressure is small and the glue is not completely removed, thereby improving the appearance and reducing the amount of glue accumulation.

[0086] (6) The heat-insulating layer of the present invention can adopt an interpenetrating phase composite material (IPC), the surface of which can be ceramicized and hardened at high temperature, and has a uniform nanoporous structure and good heat-insulating performance; compared with the high-temperature resistant resin in the prior art, the heat-insulating performance is greatly improved, and the thermal conductivity is reduced from 0.078W / (mK) to 0.066W / (mK), a decrease of 15.4%.

[0087] In the present invention, the above-mentioned technical solutions can also be combined with each other to achieve more preferred combination solutions. Other features and advantages of the present invention will be described in the subsequent description, and some advantages can become obvious from the description, or can be understood by practicing the present invention. The purpose and other advantages of the present invention can be realized and obtained through the contents particularly pointed out in the embodiments of the description and the drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0088] The drawings are only for the purpose of illustrating particular embodiments and are not to be considered limiting of the present invention. Like reference symbols denote like components throughout the drawings.

[0089] Figure 1 A schematic cross-sectional view of a composite tubular product in one embodiment of the present invention;

[0090] Figure 2 It is a schematic diagram of a state in which there is no glue accumulation at the fillet connecting the outer wall plate and the radial support structure in one embodiment of the present invention;

[0091] Figure 3 It is a schematic diagram of a state in which glue is accumulated at the fillet connecting the outer wall plate and the radial support structure in one embodiment of the present invention;

[0092] Figure 4 A schematic diagram of the process arrangement of vacuum impregnation and vacuum introduction in one embodiment of the present invention;

[0093] Figure 5 This is a schematic diagram of the internal structure of the axial support structure in one embodiment of the present invention;

[0094] Figure 6 This is a schematic diagram of laying out each layer of carbon fiber fabric prepreg in one embodiment of the present invention;

[0095] Figure 7 This is a schematic diagram of a first transition buffer structure in one embodiment of the present invention;

[0096] Figure 8 A side view of a composite tubular product in one embodiment of the present invention;

[0097] Figure 9a for Figure 8 A1-A1 cross-sectional view;

[0098] Figure 9b for Figure 8 A2-A2 cross-sectional view;

[0099] Fig.10a for Figure 9a and Figure 9b The B1-B1 cross-sectional view in FIG.

[0100] Fig.10b for Figure 9a and Figure 9b The B2-B2 cross-sectional view in FIG.

[0101] Fig.11 This is a CT image of the connection between the inner wall plate and the anti-insulation plate of Example 4;

[0102] Fig.12 This is a CT image of the connection between the inner wall plate and the anti-insulation plate of Comparative Example 2;

[0103] Fig.13 This is a picture of the finished product of Example 4 where the outer wall panel is formed with conformable rubber;

[0104] Fig.14 This is a picture of the finished product of the outer wall panel of comparative example 3 without the conformable rubber;

[0105] Fig.15 It is a schematic diagram of the second transition buffer structure in one embodiment of the present invention.

[0106] Reference numerals:

[0107] Heat-insulating layer 1; axial support structure 2; internal filling structure 202; external reinforcement structure 203; panel 2031; reinforcing rib 2032; inner wall plate 3; radial filling structure 4; outer wall plate 5; radial support structure 6; outer coating 7; outer coating body 701; annular protrusion 702; first transition buffer structure 8; first rigid connection layer 801; first toughness support layer 802; second rigid connection layer 803; 9 carbon fiber fabric prepreg; layer 901 rotated 90° relative to the bottom carbon fiber fabric prepreg layer; Bottom carbon fiber fabric prepreg layer 902; layer 903 rotated 45° counterclockwise relative to the bottom carbon fiber fabric prepreg layer; layer 904 rotated 45° clockwise relative to the bottom carbon fiber fabric prepreg layer; second transition buffer structure 10; third rigid connection layer 1001; second toughness support layer 1002; fourth rigid connection layer 1003; external glue accumulation and special-shaped area 11 of the outer wall panel; preform to be formed 12; vacuum bag 13; autoclave 14; autoclave air inlet and outlet 1401; mold 15; vacuum exhaust port 16. DETAILED DESCRIPTION

[0108] The preferred embodiments of the present invention will be described in detail below in conjunction with the accompanying drawings, wherein the accompanying drawings constitute a part of the present invention and are used together with the embodiments of the present invention to illustrate the principles of the present invention, but are not used to limit the scope of the present invention.

[0109] In order to clearly describe the technical solution of the present invention, the following terms are particularly explained:

[0110] Conformal coating: after curing, it forms a transparent protective film with excellent insulation, moisture-proof, anti-leakage, shock-proof, dust-proof, anti-corrosion, anti-aging, and corona-resistant properties.

[0111] Quasi-isotropic: A symmetrical laminate with the same stiffness in all directions within the plane and no tension-shear or shear-stretch coupling effects. The difference from an isotropic laminate is that the stiffness in the thickness direction is not necessarily the same as the in-plane stiffness; its bending stiffness performance is not isotropic either.

[0112] Chopped Strand Mat: A glass fiber fabric that is randomly distributed and bonded together after the glass fiber strands are chopped.

[0113] Fiber cloth laminated paving: multiple layers of fiber cloth are laid and glued.

[0114] Needle punching of chopped strands mat and fabric laminate: The carded chopped strands mat and fabric laminate are needle punched to mechanically entangle the fibers and reinforce the fiber web to form a felt-like material.

[0115] Fiberglass cloth is a variety of fiberglass cloth and fiberglass fabric woven with fiberglass yarn.

[0116] Release cloth: Release cloth is a process auxiliary material in the molding and curing process of composite components. It is also a material placed between the mold and the blank part to prevent the resin from sticking to the mold.

[0117] Pressure balancing plate: The pressure balancing plate is a process auxiliary material in the molding and curing process of composite components. It is also a material placed between the mold and the blank part to prevent the blank part from being subjected to uneven pressure.

[0118] Hollow isolation film: It mainly plays the role of positioning and fixing in the autoclave molding process. It allows volatiles to pass through and can absorb a certain amount of excess resin. For those with low resin content, such as prepreg vacuum molding process, non-porous isolation film is often selected.

[0119] Breathable felt: has good absorption properties. Can absorb additional resin or act as a medium in vacuum processes.

[0120] Guide net: It is a mesh structure used to promote the flow of resin when the resin is used in the vacuum process, and to quickly and effectively disperse the resin throughout the entire part.

[0121] Conformable Rubber: An uncured rubber material that can deform freely under pressure without actively rebounding.

[0122] Vacuum impregnation process: It is a vacuum application process in which the impregnation material is impregnated into other solid substances through negative pressure under vacuum conditions to improve the material properties of the substance or meet certain specific requirements.

[0123] Vacuum infusion process: refers to the process of laying glass fiber, glass fiber fabric, various inserts, release cloth, resin penetration layer, resin pipeline and covering nylon and flexible film (vacuum bag) on ​​the cured gel coat layer; the film and molding chamber are sealed, vacuumed, and the resin flows along the resin pipeline to impregnate the fiber, and further solidifies and forms.

[0124] In one aspect, the present invention provides a composite tubular article, such as Figure 1 As shown, it includes an anti-insulation layer 1, a first transition buffer structure 8, an inner wall panel 3, a radial filling structure 4 and an outer wall panel 5 arranged in sequence from the inside to the outside; the first transition buffer structure 8 is a multi-layer composite structure including a tough support layer, and the tough support layer can match the anti-insulation layer 1 and the inner wall panel 3 with different thermal expansion coefficients.

[0125] Compared with the prior art, a first transition buffer structure is arranged between the anti-insulation layer and the inner wall panel of the present invention. The flexible structure of the tough support layer greatly improves the stress difference and cracking caused by the different expansion rates of the anti-insulation layer and the inner wall panel when the temperature changes, thereby forming a good stress buffer layer as a whole.

[0126] The difference in thermal expansion coefficient between the heat-insulating layer 1 and the inner wall plate 3 is 8×10 -6 m / ℃~9×10 -6 m / ℃, the first transition buffer structure 8 is a multi-layer composite structure, fixedly connected to the outer wall of the heat-insulating layer 1, the inner wall plate 3 is fixedly connected to the outer wall of the first transition buffer structure 8, and the radial filling structure 4 is fixed to the outer wall of the inner wall plate 3. The setting of the first transition buffer structure solves the problem of easy cracking due to different thermal expansion coefficients at high temperature differences in the prior art, and the shear strength of the inner wall is increased from 55MPa to 60MPa compared with the prior art.

[0127] Specifically, a first transition buffer structure 8 is provided between the inner wall plate 3 and the heat-insulating layer 1. Figure 1 and Figure 7 As shown, the first transition buffer structure 8 comprises a first rigid connection layer 801, a first tough support layer 802 and a second rigid connection layer 803 which are sequentially distributed from the high temperature zone to the low temperature zone; the first rigid connection layer 801, the first tough support layer 802 and the second rigid connection layer 803 are connected by an adhesive. The first rigid connection layer 801 is fixedly connected to the outer wall of the anti-insulation layer 1, and the second rigid connection layer 803 is fixedly connected to the inner wall of the inner wall plate 3.

[0128] The first rigid connection layer 801 and the second rigid connection layer 803 may be glass fiber mats; the glass fiber mats may be glass fiber mats with a fiber length of 2 to 10 mm; the glass fiber mats may be chopped strands. That is, the first transition buffer structure 8 may be a transition buffer structure of glass fiber mat + glass fiber cloth + glass fiber mat.

[0129] The first toughness support layer can be made of glass fiber cloth; the glass fiber cloth can be selected from: woven cloth, twill cloth, plain cloth, preferably twill cloth with good shear tensile resistance, preferably 170g / cm 3 ~220g / cm 3 Twill cloth. Glass fiber cloth with too heavy a gram is too thick or has too dense a weaving density, which is not conducive to the adhesive entering to play a bonding role and is not conducive to improving the bonding strength; glass fiber cloth with too light a gram is too thin or has too low a weaving density, and the strength of the glass fiber cloth itself is too low, which is also not conducive to improving the bonding strength.

[0130] The adhesive comprises: high temperature resistant epoxy powder, high temperature resistant toughening agent and high temperature resistant diluent; the high temperature resistant epoxy powder may be selected from EH301 epoxy resin; the mass ratio of the high temperature resistant epoxy powder, the high temperature resistant toughening agent and the high temperature resistant diluent is 1: 0.05-0.3: 0.05-0.2.

[0131] Preferably, the expansion coefficient of the heat-insulating layer 1 is 0.13×10 -6 m / ℃~0.2×10 -6 m / ℃, the expansion coefficient of the inner wall plate 3 material is not greater than 9×10 -6 m / ℃. The thermal expansion coefficient range of the heat-insulating layer 1 and the inner wall plate 3 needs to be controlled within an appropriate range. If the difference is too large, it will not match the first toughness support layer.

[0132] Specifically, the first rigid connection layer 801 of the first transition buffer structure 8 includes 2 to 3 layers of glass fiber felt, the first toughness support layer 802 includes 1 to 3 layers of glass fiber cloth, and the second rigid connection layer 803 includes 2 to 3 layers of glass fiber felt. The first transition buffer structure 8 can be constructed by laying layers in sequence, such as laying 2 to 3 layers of glass fiber felt on the heat-insulating layer, then laying 1 to 3 layers of glass fiber cloth, and then laying 2 to 3 layers of glass fiber felt. The first transition buffer structure is constructed in this way, wherein the flexible structure of the glass fiber cloth greatly improves the stress difference and cracking caused by the different expansion rates of the heat-insulating layer and the inner wall panel when the temperature changes, and forms a good stress buffer layer as a whole; and the glass fiber felts adjacent to the heat-insulating layer and the outer wall panel are tightly fixedly connected, which effectively avoids the defects of the glass fiber cloth body being weak in strength and insufficient in shear resistance.

[0133] Specifically, the base resin of the heat-insulating layer can be one or more of phenolic resin, silicone resin, silicon-containing aromatic acetylene resin, aryl acetylene resin, or one or more modified resins of phenolic resin, silicone resin, silicon-containing aromatic acetylene resin, aryl acetylene resin.

[0134] Compared with the existing technology, the above resins have better high-temperature stability and strength: phenolic resin, silicon-containing aromatic acetylene resin, and aromatic acetylene resin contain aromatic structures and have better rigidity and high-temperature resistance; at the same time, the heat-resistant silicon-oxygen bonds contained in silicone resins and silicon-containing aromatic acetylene resins have better thermal stability than carbon-oxygen bonds.

[0135] Further preferably, the resin adopts hybrid phenolic resin PF-45, i.e., interpenetrating phase composite material modified phenolic resin, whose surface can be ceramicized at high temperature, and has better thermal insulation performance, and at the same time, its interior has a uniform nanoporous structure, which further improves the thermal insulation performance.

[0136] Preferably, the anti-insulation layer adopts a fiber-reinforced resin matrix structure, and the fiber is a mixture of one or more of quartz fiber, carbon fiber, high silica fiber, and basalt fiber. Among them, carbon fiber and quartz fiber have a hollow structure and are lightweight. Specifically, a fiber-reinforced resin-based composite material can be obtained by filling reinforcing fibers in a resin matrix to prepare the anti-insulation layer.

[0137] Compared with the existing technology, adding reinforcing materials to the resin matrix can greatly improve the strength, rigidity and wear resistance of the thermal insulation layer, and it is not easy for the thermal insulation layer to be damaged or fall off due to friction. At the same time, the reinforcing materials help to increase the glass transition temperature of the thermal insulation layer, thereby improving the high temperature resistance.

[0138] Preferably, in the heat-insulating layer, a fiber-reinforced structural layer may be arranged between layers of resin matrix material. Specifically, the fiber-reinforced structural layer may be one or more of a fiber woven structural layer, a fiber cloth laminated paving layer, a chopped strand mat layer, a chopped strand mat needle-punched layer, and a fabric laminated needle-punched layer.

[0139] Among them, the fabric laminate needling is to set a needle punching structure through the fabric laminate, and the fabric laminate needling is used to further improve the bonding strength between the layers in the anti-insulation layer, thereby improving the anti-falling ability of the anti-insulation layer.

[0140] The inner wall plate 3 may be made of a resin matrix material with a fiber-reinforced structure layer arranged between layers; the fiber-reinforced structure may be one or more of quartz fiber, carbon fiber, high silica fiber, and basalt fiber, preferably carbon fiber. The resin may be any one of phenolic resin, silicone resin, silicon-containing aromatic acetylene resin, arylacetylene resin, epoxy resin, or a modified resin of phenolic resin, silicone resin, silicon-containing aromatic acetylene resin, arylacetylene resin, and epoxy resin, preferably EH301 epoxy resin.

[0141] An axial support structure 2 is also provided between the inner wall plate 3 and the outer wall plate 5 of the present invention; the axial support structure 2 is located inside the radial filling structure 4 and is fixed to the outer wall of the inner wall plate 3. A plurality of axial support structures 2 are provided and are distributed at radial intervals on the cylindrical workpiece, which can effectively improve the axial bending and shear strength.

[0142] The axial support structure 2 includes an internal filling structure 202 and an external reinforcement structure 203 surrounding the internal filling structure 202 ; the external reinforcement structure 203 includes a panel 2031 fixedly connected to the inner wall panel 3 and reinforcing ribs 2032 surrounding and fixing the internal filling structure 202 .

[0143] The panel 2031 and the reinforcing rib 2032 may be provided with a fiber-reinforced structure layer between layers of a resin matrix material; the fiber-reinforced structure may be selected from one or more of quartz fiber, carbon fiber, high silica fiber, and basalt fiber, preferably carbon fiber. The resin may be any one of phenolic resin, silicone resin, silicon-containing aromatic acetylene resin, arylacetylene resin, epoxy resin, or a modified resin of phenolic resin, silicone resin, silicon-containing aromatic acetylene resin, arylacetylene resin, and epoxy resin, preferably EH301 epoxy resin.

[0144] The internal filling structure 202 may be made of low-density material; further, solid material or hollow material with pores or bubbles in the middle may be selected; the hollow material is preferably one of high-temperature resistant PEI foam and PMI foam or a combination of the two.

[0145] Different materials can be selected for the internal filling structure 202 and the external reinforcement structure 203; the axial support structure of the tubular component can be arranged in a manner of: a plurality of independent axial support structures are evenly arranged along the circumference of the tubular component or a plurality of axial support structure groups are evenly arranged along the circumference of the tubular component, that is, a plurality of separate axial support structures or a plurality of axial support structure groups formed by a group of several axial support structures can be arranged.

[0146] Specifically, when multiple independent axial support structures 2 are arranged evenly along the circumference of the cylindrical workpiece, there are gaps between adjacent axial support structures 2; when multiple axial support structure groups are arranged evenly along the circumference of the cylindrical workpiece, there are gaps between adjacent axial support structure groups, and there are gaps or no gaps between several axial support structures in an axial support structure group. For example, Figure 1 As shown, three axial support structures form a group to form an axial support structure group, and four axial support structure groups are evenly arranged along the circumference of the cylindrical workpiece.

[0147] It should be noted that the several axial support structures in each axial support structure group can be integrally formed or separately formed. When the several axial support structures in each axial support structure group are integrally formed, the common panel 2031 of the several axial support structures is laid as a whole, the positions of the several filling structures 202 are positioned on the common panel 2031, and then the reinforcing ribs 2032 of the external reinforcement structures 203 of the several axial support structures are laid as a whole, so as to form an integrally formed axial support structure group. At this time, there is no gap between the several axial support structures in the axial support structure group.

[0148] Compared with the prior art, the introduction of the fiber-reinforced structure enhances the strength of the resin, reduces the fluidity of the resin, improves the convenience of molding and processing of the axial support structure 2 and the inner wall plate 3, and expands the types of shapes that can be processed; at the same time, by sharing the fiber-reinforced structure with multiple axial support structures 2, it is easier to connect multiple axial support structures 2, and obtain an axial support structure 2 assembly with higher strength. Furthermore, between the outer wall of the radial filling structure 4 and the outer wall plate 5, multiple radial support structures 6 are distributed along the axial intervals of the cylindrical workpiece, such as Figure 1 As shown: the radial support structure 6 can be 2 to 5 pieces, which can effectively improve the radial bending and shearing strength.

[0149] Furthermore, the radial filling structure 4, the axial support structure 2 and the radial support structure 6 can be filled with materials with lower density, which have a lower overall weight; at the same time, the axial support structure 2 and the radial support structure 6 can be filled with lightweight materials with hollow micropores or bubble structures, which have lower weight and reduce the energy transfer rate, thus achieving heat insulation and sound insulation effects. On the one hand, the hollow structure contains gas, which has a better heat insulation effect than solid materials; on the other hand, the sound waves refract or reflect at the gas-solid interface of the hollow structure, which interferes with the incident sound waves and thus achieves a sound insulation effect.

[0150] Compared with the prior art, the tubular parts of the support structure of this embodiment have greater radial and axial bending and shear strength. In addition, since the radial filling structure 4, the axial support structure 2 and the radial support structure 6 are filled with the external reinforcement structure 203 with a density lower than that of the axial support structure 2 and the anti-insulation layer 1, the outer inner wall panel 2, and the outer wall panel 5, they have a lower overall weight.

[0151] The low-density material can be a solid material or a hollow material with pores or bubbles in the middle; the hollow material is preferably one of high-temperature resistant PEI (polyetherimide) foam and PMI (polymethacrylimide) foam or a combination of the two, which overcomes the defects of the traditional support structure, such as large mass and rapid energy transfer loss. Specifically, the radial filling structure 4, the radial support structure 6, and the internal filling structure 202 use commercially available high-temperature resistant PEI (polyetherimide) foam with a porosity of 50-70%.

[0152] like Figure 1 As shown, where the radial support structure 6 is provided, the outer wall plate 5 can be fixedly connected to the radial support structure 6 through the second transition buffer structure 10; where the radial support structure 6 is not provided, the outer wall plate 5 is fixedly connected to the radial filling structure 4 through the second transition buffer structure 10. The outer wall plate 5 can further play a supporting and heat insulating role.

[0153] The outer wall panel 5 can be made of inorganic non-metallic materials, metals, thermoplastic resins and thermosetting resins with strong rigidity; thermoplastic resins and thermosetting resins are preferred for weight reduction; thermosetting resin materials are preferred for improving rigidity at room temperature and high temperature.

[0154] The outer wall panel 5 can be made of a fiber-reinforced structural layer arranged between layers of a resin matrix material; the fiber-reinforced structure can be selected from one or more of quartz fiber, carbon fiber, high silica fiber, and basalt fiber, preferably carbon fiber. The resin is any one of phenolic resin, silicone resin, silicon-containing aromatic acetylene resin, aromatic acetylene resin, epoxy resin, or a modified resin of phenolic resin, silicone resin, silicon-containing aromatic acetylene resin, aromatic acetylene resin, and epoxy resin, preferably EH301 epoxy resin. Compared with the prior art, a second transition buffer structure is arranged between the radial support structure and the outer wall panel of the present invention, and the flexible structure of its toughness support layer greatly improves the stress difference and cracking caused by the different expansion rates of the radial support structure and the outer wall panel when the temperature changes, and forms a good stress buffer layer as a whole.

[0155] The difference in thermal expansion coefficient between the outer wall plate 5 and the radial support structure 6 or the radial filling structure 4 is within 35×10 - 6 m / ℃~41×10 -6 m / ℃, the second transition buffer structure 10 is a multi-layer composite structure, and the inner wall of the second transition buffer structure 10 is fixedly connected to the outer wall of the radial support structure 6 or the radial filling structure 4. The setting of the second transition buffer structure solves the problem of easy cracking due to different thermal expansion coefficients at high temperature difference in the prior art, and the shear strength of the outer side wall is increased from 60MPa to 70MPa compared with the prior art.

[0156] Specifically, a second transition buffer structure 10 is provided between the outer wall plate 5 and the radial support structure 6. Figure 1 and Fig.15 As shown, the second transition buffer structure 10 comprises a third rigid connection layer 1001, a second tough support layer 1002 and a fourth rigid connection layer 1003 which are sequentially distributed from the high temperature zone to the low temperature zone; the third rigid connection layer 1001, the second tough support layer 1002 and the fourth rigid connection layer 1003 are connected by an adhesive. The third rigid connection layer 1001 is fixedly connected to the outer wall of the radial support structure 6 or the radial filling structure 4, and the fourth rigid connection layer 1003 is fixedly connected to the inner wall of the outer wall plate 5.

[0157] The third rigid connection layer 1001 and the fourth rigid connection layer 1003 may be glass fiber mats; the glass fiber mats may be glass fiber mats with a fiber length of 10 mm to 15 mm for better drainage effect; the glass fiber mats may be chopped strands. That is, the second transition buffer structure 10 may be a transition buffer structure of glass fiber mat + glass fiber cloth + glass fiber mat.

[0158] The second toughness support layer can be made of glass fiber cloth. The glass fiber cloth can be selected from: woven cloth, twill cloth, plain cloth, preferably twill cloth with good shear tensile resistance, preferably 170g / cm 3 ~220g / cm 3 Twill cloth. Glass fiber cloth with too heavy a gram is too thick or has too dense a weaving density, which is not conducive to the adhesive entering to play a bonding role and is not conducive to improving the bonding strength; glass fiber cloth with too light a gram is too thin or has too low a weaving density, and the strength of the glass fiber cloth itself is too low, which is also not conducive to improving the bonding strength.

[0159] The adhesive comprises: high temperature resistant epoxy powder, high temperature resistant toughening agent and high temperature resistant diluent; the high temperature resistant epoxy powder may be selected from EH301 epoxy resin; the mass ratio of the high temperature resistant epoxy powder, the high temperature resistant toughening agent and the high temperature resistant diluent is 1: 0.05-0.3: 0.05-0.2.

[0160] Preferably, since the outer wall plate 5 and the radial support structure 6 or the radial filling structure 4 are located outside the cylindrical product, the temperature difference between the layers is much smaller than that between the heat-insulating layer 1 and the inner wall plate 3; the difference in the thermal expansion coefficient between the actual radial support structure 6 or the radial filling structure 4 and the outer wall plate 5 is allowed to have a larger range, and the expansion coefficient of the outer wall plate 5 is 9×10 -6 m / ℃~15×10 -6 m / ℃, the expansion coefficient of the radial support structure 6 or radial filling structure 4 material is not greater than 50×10 -6 m / ℃. The thermal expansion coefficient range of the heat-insulating layer 1 and the inner wall plate 3 needs to be controlled within an appropriate range. If the difference is too large, it will not match the second toughness support layer.

[0161] Specifically, the third rigid connection layer 1001 of the second transition buffer structure 10 includes 2 to 3 layers of glass fiber felt, the second toughness support layer 1002 includes 1 to 3 layers of glass fiber cloth, and the fourth rigid connection layer 1003 includes 2 to 3 layers of glass fiber felt. The second transition buffer structure 10 can be constructed by laying layers in sequence, such as laying 2 to 3 layers of glass fiber felt on the radial support structure or radial filling structure, and then laying 1 to 3 layers of glass fiber cloth, and then laying 2 to 3 layers of glass fiber felt. The second transition buffer structure is constructed in this way, wherein the flexible structure of the glass fiber cloth greatly improves the stress difference and cracking caused by the different expansion rates of the outer wall panel and the radial support structure or radial filling structure when the temperature changes, and forms a good stress buffer layer as a whole; and the glass fiber felts adjacent to the outer wall panel, radial support structure and radial filling structure are respectively tightly fixed and connected, which effectively avoids the defects of the glass fiber cloth body being weak in strength and insufficient in shear resistance.

[0162] In order to further improve the corrosion resistance, water resistance and antistatic performance of the cylindrical component, an external coating 7 may be provided on the outer side wall plate 5, and the external coating 7 may be made of a three-proof paint material.

[0163] On the other hand, the present invention also provides a molding method of a composite material cylindrical product, which is used to prepare the composite material cylindrical product, comprising the following steps:

[0164] Step 1: The heat-insulating layer 1 is impregnated and molded, and the heat-insulating layer is prepared in a mold by a vacuum impregnation process;

[0165] Specifically, the core mold and the anti-insulation layer preform are placed in a cylindrical cavity mold, the resin is introduced into the circular cavity mold, and the cylindrical cavity mold body and the cover are locked by bolts; the resin is fully infiltrated into the preform by vacuum impregnation, and the vacuum degree of vacuum impregnation shall not be lower than 980mbar; the mold temperature is raised to 80°C to 180°C by a self-heating device to cure the resin for 12h to 24h, and the anti-insulation layer is obtained after demolding and processing.

[0166] The core mold is a cylindrical mold embedded in the cylindrical cavity mold, and a cylindrical heat-insulating layer is formed in the area between the core mold and the cylindrical cavity mold.

[0167] Step 2: Laying the first transition buffer structure 8;

[0168] Specifically, taking the outer surface of the heat-insulating layer as the reference plane, apply epoxy glue on its surface, lay 2 to 3 layers of fiberglass felt, then lay 1 to 3 layers of fiberglass cloth, then lay 2 to 3 layers of fiberglass felt, spray adhesive between the laid layers, and complete the laying of the first transition buffer structure.

[0169] Compared with the prior art, in step 2, 2 to 3 layers of glass fiber mats are laid on the heat-insulating layer, followed by 1 to 3 layers of glass fiber cloth, and then 2 to 3 layers of glass fiber mats are laid. The flexible structure of the glass fiber cloth greatly improves the stress difference and cracking caused by the different expansion rates of the two connected layers when the temperature changes, and forms a good stress buffer layer as a whole; and the glass fiber mats adjacent to the heat-insulating layer and the inner wall panel are tightly fixed and connected respectively, effectively avoiding the defect that the glass fiber cloth body is not strong and easy to resist shearing. The glass fiber mat adopts one of the forms of chopped mat, chopped mat needle-punched, and fabric laminated needle-punched; the thickness of the glass fiber mat and the glass fiber cloth adopts the thickness of commonly used products on the market, and the present invention does not make special restrictions.

[0170] Step 3: Vacuum injection molding of inner wall panel 3

[0171] On the outer wall of the first transition buffer structure, the fiber skeleton of the inner wall panel preform, the demoulding cloth, the isolation film, and the guide net are laid in sequence from the side close to the heat insulation layer, the glue injection pipeline and the glue outlet pipeline are set, the glue injection port and the glue outlet are installed, the vacuum bag is laid and vacuumed to lock the vacuum bag, and the negative pressure operation is gradually increased in the range of 600 to 980 mbar after the start;

[0172] Further, follow the steps below:

[0173] Step 3.1 The inner wall panel preform placed in the vacuum bag is evacuated and transported to the heating equipment, and the temperature of the heating equipment is set to 120° C. to 130° C.;

[0174] Step 3.2: heating the resin to 100° C. to 120° C. and introducing the resin into the inner wall panel preform;

[0175] Step 3.3 After the injection is completed, the oven temperature is raised to 130℃~150℃ and kept for 3 hours, and then the oven temperature is raised to 170℃~180℃ and kept for 2 hours. The product is cooled with the furnace, and the surface is polished and cleaned after demoulding to obtain the inner wall panel. The fiber skeleton of the inner wall panel preform is selected from one or more of quartz fiber, carbon fiber, high silica fiber, and basalt fiber.

[0176] In steps 2 and 3, the selected resin may be a high temperature resistant thermosetting resin, preferably a high temperature resistant epoxy resin, a phenolic resin, or a silicone resin; more preferably, EH301 epoxy resin.

[0177] Compared with the prior art, in step 3, the resin is pre-heated to 100°C-120°C, which is lower than the heating temperature of 120°C-130°C set for the outer wall panel preform in the oven. After the injection of glue is completed, the oven temperature is raised to 130°C-150°C and kept warm for 3 hours, and then the oven temperature is raised to 170°C-180°C and kept warm for 2 hours. Since the heat dissipation between the resin and the environment is from the outside to the inside of the resin, the resin is pre-heated to a temperature lower than the temperature set for the outer wall panel preform in the oven. Such a temperature setting can accelerate the flow rate of the outer wall of the resin relative to the inside, help disperse and distribute the resin to the fine structure, reduce glue deficiency and incompleteness, and at the same time, the lower temperature can further reduce the reaction rate of the resin, which is conducive to uniform dispersion of the resin.

[0178] Compared with the prior art, the temperature setting is divided into three main stages: the first stage in which the initial temperature of the outer wall panel preform is set at 120℃~130℃ in the oven temperature setting, and the subsequent two stages of further setting the oven temperature to 130℃~150℃ and 170℃~180℃. The corresponding staged setting of temperature better matches the flow, dispersion and curing rules of resin: in the first stage, after injection, the glue mainly flows in the main trunk and large space, with small resistance, and there is no need to deliberately increase the temperature to reduce viscosity and improve fluidity. Lower temperature helps to delay curing; in the second stage, the main resin is dispersed to the fine structure. At this time, since the resin flow process has been heated, partial solidification occurs, resulting in increased viscosity and reduced fluidity. Therefore, it is necessary to appropriately increase the temperature to improve fluidity; in the third stage, since the glue has been fully dispersed in the second stage and a high degree of curing has occurred at the same time, it is necessary to further increase the temperature to increase the curing and cross-linking degree of the resin, thereby increasing the strength of the resin.

[0179] Step 4: forming the axial support structure 2, using an autoclave process to prepare the axial support structure in a mold;

[0180] Specifically, the steps include:

[0181] Step 4.1: Casting the external reinforcement structure 203 in the mold: Figure 5 As shown, carbon fiber fabric prepreg is laid on the mold sprayed with a release agent as the panel 2031 of the external reinforcement structure 203; the carbon fiber fabric prepreg is impregnated with a thermosetting resin to ensure that the carbon fiber fabric is fully coated with the thermosetting resin, and the thermosetting resin can be a single-component epoxy resin. In order to ensure the tightness of the fiber prepreg and the uniform thickness of each layer of the fiber prepreg, the fiber prepreg is vacuum compacted once every 3 to 5 layers; the time is 15 minutes to 50 minutes, and the negative pressure operation is gradually increased in the range of 600mbar to 980mbar after the start of the negative pressure operation.

[0182] Compared with the existing technology, laying carbon fiber fabric prepreg is more conducive to complete penetration of glue into the carbon fiber to achieve a more uniform effect than the carbon fiber glue injection process; vacuum compaction once every 3 to 5 layers of fiber prepreg is helpful to exhaust the gas and make the force uniform, thereby controlling the morphology after molding.

[0183] Step 4.2: Use laser projection to locate the position of the internal filling structure 202 on the panel 2031, such as Figure 5As shown, prepreg is laid layer by layer on the foam processed into a suitable shape as the reinforcement 2032 of the external reinforcement structure 203; after one layer of prepreg is laid, it is positioned by a positioning tool and pre-compacted by hot compaction, the compaction temperature is 130℃~140℃, and the compaction time is 15min~30min; after the prepreg layers are laid in sequence by the same method, a release cloth, an equalizing plate, a porous isolation membrane, and a breathable felt are laid in sequence on the outside of the outermost prepreg layer and placed inside a vacuum bag with exhaust holes.

[0184] Compared with the prior art, the use of a positioning tool to position and hot-press each layer of prepreg after paving can ensure the completeness of the molding to the greatest extent. The use of a positioning tool replaces the vacuum bagging molding process in the prior art, and vacuuming is only performed after all prepregs are laid, which greatly simplifies the vacuum molding process compared with the prior art. At the same time, the positioning tool that matches the shape of the internal filling structure 202 can greatly avoid the phenomenon of residual glue at the rounded corners of the contact between the foam and the panel 2031, thereby ensuring the stability of the designed shape.

[0185] Step 4.3: Transfer the vacuum bag and the axial support structure inside the vacuum bag to the autoclave, evacuate the vacuum bag to negative pressure, and gradually increase the negative pressure within the range of 600mbar to 980mbar after the negative pressure operation begins; raise the temperature of the autoclave to 130℃ to 150℃ and keep it for 3h-4h, then raise the temperature of the autoclave to 170℃ to 180℃ and keep it for 2h-4h, and the molding pressure is 0.4MPa to 0.6MPa; during this period, the vacuum bag maintains a stable vacuum state; the rough finished product of the axial support structure is cooled with the furnace, and the axial support structure is obtained by trimming after demoulding.

[0186] Compared with the prior art, the negative pressure operation of this method adopts a method of gradually increasing the pressure within the range of 600mbar to 980mbar after the start, which is conducive to gradually increasing the vacuum pressure and exhaust capacity as the thermosetting resin solidifies and the viscosity increases, ensuring that the resin-containing material is subjected to continuous and stable pressure from the outside of the vacuum bag during the resin curing process, avoiding the phenomenon of compression weakness and large molding thickness as the resin viscosity increases under negative pressure conditions; at the same time, it also avoids the resin overflow and waste caused by excessive vacuum pressure and fast compression speed when the resin viscosity is low in the initial stage. Compared with the prior art, the rough finished product of the axial support structure is cooled with the furnace, which can minimize the temperature difference between the inside and outside of the axial support device and avoid stress caused by different thermal expansion coefficients between the foam and the external reinforcement structure.

[0187] Furthermore, the carbon fiber fabric prepregs of the present invention can obtain a quasi-isotropic structure by adjusting the laying angle. The carbon fiber fabric prepreg must contain at least 4 layers, and each layer must have the same stiffness and thickness. The bottom layer of carbon fiber fabric prepreg is initially set as the 0° layer, and its fiber placement direction is the initial zero degree. The fiber laying directions of the remaining layers of carbon fiber fabric prepreg are different from the fibers of the bottom layer of carbon fiber fabric prepreg in the laying plane and have a certain inclination angle. The fibers in different directions also have specific strengths, such as Figure 6 As shown:

[0188] Bottom carbon fiber fabric prepreg layer (0° layer) 902: provides axial strength and stiffness, ideal for components that must withstand axial loads.

[0189] A layer (45° layer) 903 rotated 45° counterclockwise relative to the underlying carbon fiber fabric prepreg layer: provides shear and torsional strength and stiffness.

[0190] 45° layer (-45° layer) rotated clockwise relative to the bottom carbon fiber fabric prepreg layer 904: provides shear and torsional strength and stiffness.

[0191] The 90° layer (90° layer) 901 is rotated relative to the underlying carbon fiber fabric prepreg layer: it provides lateral strength and stiffness, holds the layers together and provides resistance to compression.

[0192] Compared with the prior art, the carbon fiber fabric prepregs described in the present invention can obtain a quasi-isotropic structure by adjusting the laying angle, and simultaneously have axial strength and stiffness, shear and torsional strength and stiffness, and shear and torsional strength and stiffness; the quasi-isotropic structure can produce a hard material with strength in all directions.

[0193] Step 5: Assemble the inner wall panel and the axial support structure;

[0194] Specifically, in step 3, the imported inner wall panel is fixedly connected to the preset position of the axial support structure to obtain a cylindrical preform covered with the axial support structure; the outer surface of the inner wall panel is roughened by electric grinding, and the outer surface of the inner wall panel is cleaned with a cleaning agent such as acetone or ethanol.

[0195] Among them, the adhesive film is laid to the preset position by laser projection, the axial support structure is placed on the adhesive film, the axial support structure is positioned, the demoulding cloth and breathable felt are laid, the exhaust port is arranged and the bag is made, the axial support structure and the assembly are transferred to the oven, and the negative pressure operation is gradually increased in the range of 600mbar to 980mbar after the start of the negative pressure operation, the oven temperature is raised to 130℃ to 150℃ and kept warm for 3h, and then the oven temperature is raised to 170℃ to 180℃ and kept warm for 2h to solidify the adhesive film, and after demoulding, the remaining axial support structures are assembled in the same way. After the assembly is completed, the glue accumulation area is processed to obtain a cylindrical part with an axial support structure. The adhesive film selected in this step can be a high-temperature resistant thermosetting resin adhesive film, preferably a high-temperature resistant epoxy resin or silicone resin; further preferably, the adhesive film EH601 high-temperature resistant structural adhesive film; the thickness of the adhesive film is 0.1mm to 0.2mm, and the number of layers of the paved adhesive film is 1 to 2 layers.

[0196] Step 6: Fixing the radial filling structure and radial support structure

[0197] A radial filling structure is bonded and fixed to the outer wall of a cylindrical preform covered with an axial support structure; a radial support structure is further bonded and fixed to the outer wall of the radial filling structure, and cured under vacuum to obtain a cylindrical preform with a radial filling structure and a radial support structure.

[0198] Specifically, the steps include:

[0199] Step 6.1: Fix the cut radial filling structure to the inner wall plate coated with adhesive, further use a positioning tool to position the radial supporting structure of the radial supporting structure on the outer wall of the radial filling structure, lay glass fiber prepreg between the radial supporting structure and the radial filling structure, and lay release cloth, isolation film, and breathable felt on the remaining sides of the radial supporting structure in sequence. Place the laid radial supporting structure and the initial cylindrical product in a vacuum bag and arrange an exhaust port; glass fiber is selected in the glass fiber prepreg, and the present invention does not make special limitations; the resin selected in the glass fiber prepreg can be a high-temperature resistant thermosetting resin, preferably phenolic resin, silicone resin, silicon-containing aromatic acetylene resin, aromatic acetylene resin and epoxy resin or one or more modified resins of phenolic resin, silicone resin, silicon-containing aromatic acetylene resin, aromatic acetylene resin and epoxy resin; EH301 epoxy resin is further preferred.

[0200] Schematic diagram of vacuum impregnation process or vacuum introduction process Figure 4As shown: the preform 12 to be formed is placed inside the vacuum bag 13; the vacuum bag 13, the preform 12 to be formed and the mold 15 are sealed and placed in the autoclave 14, and connected to the outside of the autoclave 14 through the vacuum exhaust port 16. The autoclave 14 is provided with an autoclave air inlet and outlet 1401, through which the hot compressed gas with adjustable pressure can be introduced to adjust the air pressure and temperature inside the autoclave 14; when the vacuum bag 13 is evacuated, the air intake of the autoclave 14 can apply pressure to the vacuum bag 13 and the preform 12 to complete the hot pressing and shaping of the preform 12 to be formed.

[0201] Compared with the prior art, the addition of isolation film and breathable felt in this step can absorb more resin and guide excess resin, thereby preventing excess resin from accumulating and affecting the appearance of the finished product.

[0202] Step 6.2: Keep the vacuum bag and the initial tubular product at 130℃~150℃ for 2h~6h, and then further heat it to 170℃~180℃ for 1h~4h to cure the prepreg. Compared with the prior art, this step adopts a two-stage heating process to control the resin flow and curing rate, and then cures after the resin is fully flowed and dispersed. Too fast curing of the resin will lead to insufficient polymerization flow, and uneven dispersion will lead to partial lack of glue. If the first heating time is too long, the residual effective glue content of the glass fiber prepreg will be less, which is not conducive to improving the connection strength of the radial support structure and the initial tubular product.

[0203] Step 7: Lay the second transition buffer structure

[0204] On the fixed radial support structure completed in step 6, 2 to 3 layers of glass fiber mats are laid, and then 1 to 3 layers of glass fiber cloth are laid, and then 2 to 3 layers of glass fiber mats are laid to complete the laying of the second transition buffer structure.

[0205] Step 8: Vacuum molding of the outer wall panel

[0206] On the outside of the second transition buffer structure that has been laid, an outer wall panel is prepared on the outer wall of the cylindrical preform having a radial support structure by using a vacuum introduction process.

[0207] The inventors found that the on-site foaming process of PEI (polyetherimide) foam, PMI (polymethacrylimide) foam and ordinary foam is different. In the prior art, the process of pre-forming, cutting and assembly is adopted, and the thermosetting molding process of the outer wall panel 5 has the following defects, such as Figure 3 As shown:

[0208] (1) Glue accumulation at the corners of the radial support structure;

[0209] (2) The edges and corners of the radial support structure have an irregular appearance.

[0210] Figure 2 Indicates that there is no glue accumulation, which is normal. Figure 3 Indicates the presence of glue accumulation and irregular shapes, where 5 represents the outer wall panel, and 11 represents the glue accumulation and irregular shape area outside the outer wall panel.

[0211] The above defects seriously affect the use of the product and are also the main influencing factors that PEI (polyetherimide) foam and PMI (polymethacrylimide) foam in the prior art cannot be directly used to reduce the weight of the supporting structure.

[0212] In order to improve the above defects, the present invention also provides a method for forming an outer wall plate of a cylindrical workpiece provided with a radial support structure, which specifically comprises the following steps:

[0213] On the outside of the second transition buffer structure that has been laid, lay the fiber skeleton of the outer wall panel preform, demoulding cloth, isolation film, and 2 layers of guide net; when laying the demoulding cloth and guide net, the fillet needs to be cut and overlapped, and conformable rubber is placed at the fillet to ensure the quality of the fillet of the outer wall panel; set the glue injection pipeline and the glue outlet pipeline, install the glue injection port and the glue outlet, lay the vacuum bag film and evacuate the vacuum bag film to lock it, transport the outer wall panel preform to the heating equipment, set the oven temperature to 120℃~130℃, heat the resin to 100℃~120℃, introduce the resin into the outer wall panel preform, after the glue injection is completed, raise the oven temperature to 130℃~150℃ and keep it warm for 3h, then raise the oven temperature to 170℃~180℃ and keep it warm for 2h, the product is cooled with the furnace, and the surface is polished and cleaned after demoulding to obtain the outer wall panel. The outer wall panel preform fiber is selected from one or more of quartz fiber, carbon fiber, high silica fiber and basalt fiber.

[0214] In the heat-insulating layer, a fiber-reinforced structural layer can be arranged between the layers of the resin matrix material. Specifically, the fiber-reinforced structural layer adopts one or more of a fiber woven structural layer, a fiber cloth laminated paving layer, a chopped felt layer, a chopped felt needle-punched layer, and a fabric laminated needle-punched layer. The resin selected in this step can be one or more of phenolic resin, silicone resin, silicon-containing aromatic acetylene resin, aromatic acetylene resin, and epoxy resin, or one or more of modified resins of phenolic resin, silicone resin, silicon-containing aromatic acetylene resin, aromatic acetylene resin, and epoxy resin, preferably high-temperature resistant epoxy resin, phenolic resin, and silicone resin; more preferably, EH301 epoxy resin.

[0215] Compared with the prior art, the present embodiment adopts 2 to 3 layers of glass fiber felt, 1 to 3 layers of glass fiber cloth, and 2 to 3 layers of glass fiber felt on the radial support structure or the radial filling structure, and thus constructs a second transition buffer structure. The flexible structure of the glass fiber cloth greatly improves the stress difference and cracking caused by the different expansion rates of the outer wall panel and the radial support structure or the radial filling structure when the temperature changes, thereby forming a good stress buffer layer as a whole. The glass fiber felts adjacent to the outer wall panel, the radial support structure and the radial filling structure are respectively tightly fixed and connected, thereby effectively avoiding the defects of the glass fiber cloth body having weak strength and insufficient shear resistance.

[0216] Compared with the prior art, in step 8, the resin is pre-heated to 100°C-120°C, which is lower than the heating temperature of 120°C-130°C set for the outer wall panel preform in the oven. After the injection of glue is completed, the oven temperature is raised to 130°C-150°C and kept warm for 3 hours, and then the oven temperature is raised to 170°C-180°C and kept warm for 2 hours. Since the heat dissipation between the resin and the environment is from the outside to the inside of the resin, the resin is pre-heated to a temperature lower than the temperature set for the outer wall panel preform in the oven. Such a temperature setting can accelerate the flow rate of the outer wall of the resin relative to the inside, help disperse and distribute the resin to the fine structure, reduce glue deficiency and incompleteness, and at the same time, the lower temperature can further reduce the reaction rate of the resin, which is conducive to uniform dispersion of the resin.

[0217] Compared with the prior art, the temperature setting is divided into three main stages: the first stage in which the initial temperature of the outer wall panel preform is set at 120℃~130℃ in the oven temperature setting, and the subsequent two stages of further setting the oven temperature to 130℃~150℃ and 170℃~180℃. The corresponding staged setting of temperature better matches the flow, dispersion and curing rules of resin: in the first stage, after injection, the glue mainly flows in the main trunk and large space, with small resistance, and there is no need to deliberately increase the temperature to reduce viscosity and improve fluidity. Lower temperature helps to delay curing; in the second stage, the main resin is dispersed to the fine structure. At this time, since the resin flow process has been heated, partial solidification occurs, resulting in increased viscosity and reduced fluidity. Therefore, it is necessary to appropriately increase the temperature to improve fluidity; in the third stage, since the glue has been fully dispersed in the second stage and a high degree of curing has occurred at the same time, it is necessary to further increase the temperature to increase the curing and cross-linking degree of the resin, thereby increasing the strength of the resin.

[0218] Compared with the existing technology, when laying the release cloth and the guide net, the rounded corners need to be cut and overlapped, which can greatly increase the glue outflow rate of excess glue and help reduce glue accumulation. On the other hand, placing conformable rubber at the rounded corners can greatly improve the problem of low pressure given by the vacuum bag at the rounded corners and inability to tighten effectively when vacuuming. The vacuum bag applies pressure through the conformable rubber to promote glue discharge and reduce glue accumulation. At the same time, due to the non-rebound characteristics of the conformable rubber after being subjected to pressure, the stable quality of the rounded shape design of the outer wall panel is guaranteed.

[0219] Step 9: Triple-proof coating:

[0220] The surface of the cylindrical prefabricated member after the outer wall panel preparation is brushed with three-proof paint as an external coating.

[0221] In order to illustrate the technical advancement of the present invention, the thermal conductivity of the thermosetting resin material involved in the present invention is tested using GB / T 3139-2005 "Test method for thermal conductivity of fiber reinforced plastics".

[0222] In order to illustrate the technical advancement of the present invention, the shear strength of the thermosetting resin material involved in the present invention is tested using GB / T 1450.1-2005 “Test method for interlaminar shear strength of fiber reinforced plastics”.

[0223] In order to illustrate the technical progress of the present invention, the following embodiments and comparative examples are further disclosed:

[0224] Example 1

[0225] This embodiment discloses a molding method of a composite material cylindrical product, which is used to process the composite material cylindrical product, comprising:

[0226] Step 1: Dip-molding of thermal insulation layer

[0227] Place the core mold and the preform into the cylindrical cavity mold, introduce the resin into the circular cavity mold, lock the cylindrical cavity mold body and the cover plate by bolt locking, use vacuum impregnation to fully infiltrate the preform with the resin, the vacuum degree of vacuum impregnation is not less than 980mbar, use a self-heating device to raise the mold temperature to 90°C to cure the resin for 24 hours, and obtain the heat-insulating layer after demoulding and processing. The core mold is a cylindrical mold nested in the cylindrical cavity mold, and a cylindrical heat-insulating layer is formed in the area between the core mold and the cylindrical cavity mold.

[0228] Step 2: Lay the first transition buffer structure

[0229] Take the outer surface of the heat-insulating layer as the reference plane, apply epoxy glue on its surface, lay 3 layers of fiberglass felt, then lay 3 layers of fiberglass cloth, and then lay 3 layers of fiberglass felt, and spray adhesive between the laid layers to complete the laying of the first transition buffer structure.

[0230] Step 3: Vacuum injection molding of the inner wall panel

[0231] On the outside of the first transition buffer structure, the fiber skeleton of the inner wall panel preform of the carbon fiber fabric is laid, and vacuum compaction is performed once every 3 to 5 layers. Then, the demoulding cloth, isolation film, and guide net are laid in sequence, and the glue injection pipeline and the glue outlet pipeline are set, and the glue injection port and the glue outlet are installed. The vacuum bag film is laid and vacuumed to lock the vacuum bag film; the inner wall panel preform is transported to the heating equipment, the oven temperature is set to 130℃, the resin is heated to 120℃, and the resin is introduced into the inner wall panel preform. After the glue injection is completed, the oven temperature is raised to 150℃ for 3h, and then the oven temperature is raised to 180℃ for 2h. The product is cooled with the furnace, and the surface is polished and cleaned after demoulding to obtain the inner wall panel. The adhesive contains: EH301 epoxy resin powder, high temperature toughening agent, and high temperature diluent; the mass ratio of the amount is: 1:0.31:0.1; it can be used for a long time at 100℃ without aging. The resin used in this step is EH301 epoxy resin. The fiber skeleton of the inner wall panel preform is made of carbon fiber.

[0232] Step 4: Axial support structure molding

[0233] Step 4.1: Casting the external reinforcement structure 203 in the mold:

[0234] The carbon fiber fabric prepreg is laid on the mold sprayed with the release agent as the panel 2031 of the external reinforcement structure 203; the carbon fiber fabric prepreg is impregnated with a thermosetting resin to ensure that the carbon fiber fabric is fully coated with the thermosetting resin, and the thermosetting resin is EH301 epoxy resin. In order to ensure the tightness of the fiber prepreg and the uniform thickness of each layer of the fiber prepreg, the fiber prepreg is vacuum compacted once every 3 layers; the time is 15 minutes, and the negative pressure operation gradually increases between 600mbar and 980mbar after the start of the operation, and the increase rate is 10mbar / min.

[0235] Step 4.2: Use laser projection to locate the position of the internal filling structure 202 on the panel 2031, such as Figure 5As shown, prepreg is laid layer by layer on the foam processed into a suitable shape as the reinforcement 2032 of the external reinforcement structure 203; after one layer of prepreg is laid, it is positioned by a positioning tool and pre-compacted by hot compaction at a temperature of 140°C for 50 minutes; after each layer of prepreg is laid in turn by the same method, a release cloth, a pressure equalizing plate, a porous isolation membrane, and a breathable felt are laid in turn on the outside of the outermost layer of prepreg and placed inside a vacuum bag with exhaust holes.

[0236] Step 4.3: Transfer the vacuum bag and the axial support structure inside the vacuum bag to the autoclave, evacuate the vacuum bag to negative pressure, and gradually increase the negative pressure within the range of 600 mbar to 980 mbar after the operation begins; the increase rate is 5 mbar / min, the temperature of the autoclave is raised to 130°C and kept for 3 hours, and then the temperature of the autoclave is raised to 170°C and kept for 2 hours, and the molding pressure is 0.4 MPa; during this period, the vacuum bag maintains a stable vacuum state; the rough finished product of the axial support structure is cooled with the furnace, and the axial support structure is obtained by trimming after demoulding.

[0237] Step 5: Assemble the inner wall and axial support structure

[0238] In step 3, the preset position of the imported inner wall panel is fixedly connected to the axial support structure, the outer surface of the inner wall panel is roughened by electric grinding, and the outer surface of the inner wall panel is cleaned with cleaning agent acetone, the adhesive film is laid to the preset position by laser projection, the axial support structure is placed on the adhesive film, the axial support structure is positioned by gluing tooling, the demoulding cloth and breathable felt are laid in sequence, the exhaust port is arranged and the bag is made, the assembly is transferred to the oven, the oven temperature is raised to 150℃ and kept warm for 3h, and then the oven temperature is raised to 180℃ and kept warm for 2h to solidify the adhesive film, and after demoulding, the remaining axial support structures are assembled in the same way. After assembly, the glue accumulation area is processed to obtain a cylindrical part with an axial support structure. The adhesive film selected in this step is the EH601 high temperature resistant structural adhesive film; the thickness of the adhesive film is 0.1mm, and the number of layers of the adhesive film is 2.

[0239] Step 6: Fixing the radial filling structure and radial support structure

[0240] In the molding method of the cylindrical product of the axial support structure, epoxy glue is brushed on the outer wall of the cylindrical product of the axial support structure prepared in step 4, and the cut foam is bonded to serve as the radial filling structure 4; the radial support structure is further positioned on the outer wall of the radial filling structure 4, and glass fiber prepreg is laid between the radial support structure and the initial cylindrical product, and a release cloth, an isolation film, and a breathable felt are laid on the remaining sides of the radial support structure in sequence, and the radial support structure and the initial cylindrical product are placed in a vacuum bag after laying, and an exhaust port is arranged; the resin in the glass fiber prepreg is EH301 epoxy resin; the vacuum bag and the initial cylindrical product are kept at 150°C for 3 hours, and then further heated to 180°C and kept for 2 hours to cure the prepreg.

[0241] Step 7: Lay the second transition buffer structure

[0242] Lay 3 layers of fiberglass mat on the radial support structure installed in step 6, then lay 1 layer of fiberglass cloth, and then lay 3 layers of fiberglass mat to complete the laying of the second transition buffer structure.

[0243] Step 8: Vacuum molding of the outer wall panel

[0244] On the outside of the second transition buffer structure that has been laid, the fiber skeleton of the outer wall panel preform is laid, and vacuum compaction is performed once every 3 to 5 layers. The demoulding cloth, isolation film, and 2 layers of guide net are laid in sequence. When laying the demoulding cloth and the guide net, the fillet needs to be cut and overlapped, and conformable rubber is placed at the fillet to ensure the quality of the fillet of the outer wall panel. The glue injection pipeline and the glue outlet pipeline are set, the glue injection port and the glue outlet are installed, the vacuum bag film is laid and vacuumed to lock the vacuum bag film, the outer wall panel preform is transported to the heating equipment, the oven temperature is set to 130°C, the resin is heated to 110°C, and the resin is introduced into the outer wall panel preform. After the glue injection is completed, the oven temperature is raised to 140°C for 3 hours, and then the oven temperature is raised to 170°C for 2 hours. The product is cooled with the furnace, and the surface is polished and cleaned after demoulding to obtain the outer wall panel. The glass fiber mat is in the form of chopped strand mat; the resin used in this step is EH301 epoxy resin. The outer wall panel preform fiber is quartz fiber.

[0245] Step 9: Apply conformal coating as an external coating on the surface of the cylindrical prefabricated part of the outer wall panel.

[0246] Example 2

[0247] This embodiment discloses a composite material cylindrical product, which is prepared by the molding method of the composite material cylindrical product.

[0248] like Figure 1As shown, from the inside to the outside, there are sequentially provided an anti-insulation layer 1, a first transition buffer structure 8 fixedly connected to the outer wall of the anti-insulation layer 1, an inner wall plate 3 fixedly connected to the outer wall of the first transition buffer structure 8, a radial filling structure 4 fixed to the outer wall of the inner wall plate 3, and an outer wall plate 5 fixedly connected to the outer wall of the radial filling structure 4.

[0249] Figure 8 The appearance of the cylindrical product is shown. It can be seen that the outer coating 7 is provided with an outer coating body 701 and a protruding annular protrusion 702; a cross-sectional view is obtained by cutting the A1-A1 section from the center line of the annular protrusion 702. Figure 9a ; Cut A2-A2 section from any part of the outer coating body 701 to obtain a cross-sectional view Figure 9b .

[0250] like Figure 9a or Figure 9b As shown, the cylindrical product is further provided with: an axial support structure 2 located inside the radial filling structure 4 and fixed to the outer wall of the inner wall plate 3, wherein two axial support structures 2 are provided and are distributed at intervals in the radial direction of the cylindrical product.

[0251] like Figure 9a As shown, the cylindrical component is also provided with: a radial support structure 6 fixed to the outer wall of the radial filling structure 4, and the axial support structure 2 passes through the radial support structure 6; four radial support structures 6 are provided and are distributed at intervals in the axial direction of the cylindrical component; the axial support structure 2 is inside the radial filling structure 4, and is connected to the outer wall plate 5 on the outside, and the outer wall plate 5 and the remaining side surfaces of the radial support structure 6 are fixedly connected.

[0252] The internal filling structure 202 inside the axial support structure 2 is surrounded by the external reinforcement structure 203 ; each axial support structure 2 is provided with three identical units that are fixedly connected and arranged circumferentially, and each unit is provided with an internal filling structure 202 .

[0253] exist Figure 9a or Figure 9b In the figure, a cross-sectional view of the B2-B2 section obtained by axially cutting through the center of any axial support structure 2 Fig.10b ; A cross-sectional view of the B1-B1 section obtained by cutting at any position without the axial support structure 2 Fig.10a .

[0254] like Fig.10a As shown, from inside to outside, there are: a heat-insulating layer 1, an inner wall plate 3, an axial support structure 2, a radial filling structure 4, an outer wall plate 5, and an outer coating 7; the radial support structure 6 is distributed between the radial filling structure 4 and the outer wall plate 5 along the axial direction.

[0255] like Fig.10bAs shown, from inside to outside, there are: a heat-insulating layer 1, an inner wall plate 3, an axial support structure 2, an outer wall plate 5, and an outer coating 7; the radial support structure 6 is distributed between the radial filling structure 4 and the outer wall plate 5 along the axial direction.

[0256] Furthermore, if Figure 7 As shown, the first transition buffer structure 8 includes a first rigid connection layer 801, a first tough support layer 802 and a second rigid connection layer 803 which are distributed in sequence from the high temperature zone to the low temperature zone; the first rigid connection layer 801, the first tough support layer 802 and the second rigid connection layer 803 are connected by an adhesive.

[0257] like Fig.10a or Fig.10b As shown, a second transition buffer structure 10 is provided between the outer wall plate 5 and the radial support structure 6 or the radial filling structure 4, and the outer wall plate 5 and the radial support structure 6 are fixedly connected through the second transition buffer structure 10, and the outer wall plate 5 and the radial filling structure 4 are fixedly connected through the second transition buffer structure 10. Fig.15 As shown, the second transition buffer structure 10 comprises a third rigid connection layer 1001, a second tough support layer 1002 and a fourth rigid connection layer 1003 which are sequentially distributed from the high temperature zone to the low temperature zone; the third rigid connection layer 1001, the second tough support layer 1002 and the fourth rigid connection layer 1003 are connected by an adhesive. The third rigid connection layer 1001 is fixedly connected to the outer wall of the radial support structure 6 or the radial filling structure 4, and the fourth rigid connection layer 1003 is fixedly connected to the inner wall of the outer wall plate 5.

[0258] Glass fiber felt may be used for the first rigid connection layer 801, the second rigid connection layer 803, the third rigid connection layer 1001 and the fourth rigid connection layer 1003; the glass fiber felt of the third rigid connection layer 1001 and the fourth rigid connection layer 1003 may be glass fiber felt with a fiber length of 12 mm for better drainage effect; the first rigid connection layer 801 and the second rigid connection layer 803 may be glass fiber felt with a fiber length of 10 mm; and the glass fiber felt may be chopped strands.

[0259] The first toughness support layer 802 and the second toughness support layer 1002 may be made of glass fiber cloth; woven cloth, twill cloth, plain cloth, preferably twill cloth with good shear tensile resistance, preferably 190g / cm 3 Twill.

[0260] The adhesive includes: high temperature resistant epoxy powder, high temperature resistant toughening agent and high temperature resistant diluent; the high temperature resistant epoxy powder can select EH301 epoxy resin; the mass ratio of high temperature resistant epoxy powder, high temperature resistant toughening agent and high temperature resistant diluent is: 1:0.3:0.05, the high temperature resistant toughening agent selects the commonly used alicyclic amine toughening agent, and the high temperature resistant diluent selects the small molecule alicyclic epoxy.

[0261] Preferably, the expansion coefficient of the outer wall plate 5 is 10.5×10 -6 m / ℃, the expansion coefficient of the material of the radial support structure 6 or radial filling structure 4 shall not be greater than 40×10 -6 m / ℃; the expansion coefficient of the heat-insulating layer 1 is 0.15×10 -6 m / ℃, the expansion coefficient of the inner wall plate 3 material is 7.5×10 -6 m / ℃.

[0262] The base resin of the heat-insulating layer 1 is hybrid phenolic resin PF-45, the reinforcing fiber of the heat-insulating layer is carbon fiber, and the reinforcing material of the heat-insulating layer is fabric laminated needle punching.

[0263] The radial filling structure 4, the radial supporting structure 6 and the internal filling structure 202 are made of commercially available high temperature resistant PEI (polyetherimide) foam with a porosity of 60%. Please see Table 1 for the resins used in each part.

[0264] The thermal conductivity of the prepared heat-insulating layer 1 is tested using GB / T 3139-2005 “Test method for thermal conductivity of fiber-reinforced plastics”.

[0265] GB / T 1450.1-2005 “Test method for interlaminar shear strength of fiber reinforced plastics” is used to test the shear strength of the inner wall and the outer wall. Please see Table 2 for details.

[0266] Comparative Example 1

[0267] This embodiment discloses a composite tubular product and a molding method thereof. Compared with Embodiment 1, the resin of the heat-insulating layer is changed from hybrid phenolic resin PF-45 to EH301 epoxy resin, and the rest is the same as Embodiment 1. Please see Table 1 for details.

[0268] Comparative Example 2

[0269] The present embodiment discloses a composite tubular product and a molding method thereof. Compared with the first embodiment, the structure of the connection between the inner wall and the heat-insulating layer is changed from "glass fiber felt + glass fiber cloth + glass fiber felt" to "glass fiber felt + glass fiber felt". The rest is the same as the first embodiment. For details, please see Table 1.

[0270] Comparative Example 3

[0271] This embodiment discloses a composite tubular product and a molding method thereof. Compared with Embodiment 1, no conformal rubber is provided at the fillets of the outer wall panel and the radial support structure during the molding process of the outer wall panel. The rest is the same as Embodiment 1. For details, please see Table 1.

[0272] Table 1

[0273]

[0274] Table 2

[0275] Experimental Group Thermal conductivity / W / (mK) Inner wall shear strength / MPa Outer wall shear strength / MPa Example 1 0.066 60 70 Comparative Example 1 0.078 - - Comparative Example 2 - 55 60

[0276] Example 1 of the present invention adopts a new IPC resin in the anti-insulation layer. The surface can be ceramicized and hardened at high temperature, and has a uniform nanopore structure and good thermal insulation performance. Compared with the high-temperature resistant resin in the prior art, the thermal insulation performance is greatly improved, and the thermal conductivity is reduced from 0.078W / (mK) to 0.066W / (mK) compared with Comparative Example 1, a decrease of 15.4%.

[0277] Compared with Example 2 which does not contain glass fiber cloth, Example 1 of the present invention which adopts the "glass fiber felt + glass fiber cloth + glass fiber felt" structure at the connection between the inner wall and the anti-insulation layer has significantly improved the shear strength of the inner / outer walls. The shear strength of the inner wall is increased from 55 MPa to 60 MPa, and the shear strength of the outer wall is increased from 60 MPa to 70 MPa, which are increased by 9.09% and 16.6% respectively.

[0278] At the same time by Fig.11 and Fig.12 By comparison, it can be seen that after 1000 launches, the connection between the inner wall plate and the anti-insulation plate of Example 1 still showed no obvious cracking and stress peeling; while the connection between the inner wall plate and the anti-insulation plate of Comparative Example 2 showed obvious cracking (such as Fig.12 The glass fiber cloth layer can produce a certain degree of "creep deformation" when subjected to external force; the flexible structure of the glass fiber cloth greatly improves the stress difference and cracking caused by the different expansion rates of the foam and the outer wall panel when the temperature changes, and forms a good stress buffer layer as a whole; the radial filling structure and the glass fiber felt adjacent to the outer wall panel are tightly fixed and connected, effectively avoiding the defect that the glass fiber cloth body is not strong and easy to resist shearing.

[0279] At the same time by Fig.13 and Fig.14 From the comparison, it can be seen that Example 1 of the present invention has better appearance and less rubber accumulation at the rounded corners of the radial support structure than Comparative Example 3 in which no accompanying rubber is added, because accompanying rubber is added at the rounded corners of the radial support structure.

[0280] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by any technician familiar with the technical field within the technical scope disclosed by the present invention should be covered within the protection scope of the present invention.

Claims

1. A composite tubular product, characterized in that: It comprises a heat-insulating layer (1), a first transition buffer structure (8), an inner wall plate (3), a radial filling structure (4) and an outer wall plate (5) which are arranged in sequence from the inside to the outside; The first transition buffer structure (8) is a multi-layer composite structure including a tough support layer, and the tough support layer can match the heat-insulating layer (1) and the inner wall plate (3) having different thermal expansion coefficients; The first transition buffer structure (8) comprises a first rigid connection layer (801), a first toughness support layer (802) and a second rigid connection layer (803) which are sequentially distributed from the high temperature zone to the low temperature zone; The first rigid connection layer (801) is a glass fiber felt layer, the first toughness support layer (802) is a glass fiber cloth layer, and the second rigid connection layer (803) is a glass fiber felt layer; The anti-heat-insulating layer (1) adopts a fiber-reinforced resin matrix structure; The matrix resin of the fiber-reinforced resin matrix structure is an interpenetrating composite material modified phenolic resin.

2. A composite tubular product according to claim 1, characterized in that: The difference in thermal expansion coefficient between the heat-insulating layer (1) and the inner wall plate (3) is 8×10 -6 m / ℃~9×10 -6 m / ℃.

3. A composite tubular article according to claim 2, characterized in that: The first rigid connection layer (801) has 2 to 3 layers of glass fiber felt, the first toughness support layer (802) has 1 to 3 layers of glass fiber cloth, and the second rigid connection layer (803) has 2 to 3 layers of glass fiber felt.

4. A composite tubular article according to claim 3, characterized in that: The fiber length of the glass fiber mat is 2 mm to 10 mm; the glass fiber mat is chopped strands; and the glass fiber cloth is a textured cloth.

5. A composite tubular article according to claim 4, characterized in that: The woven fabric is any one of twill fabric and plain fabric.

6. A composite tubular product according to claim 5, characterized in that: The density of the twill fabric is 170 g / cm 3 ~220g / cm 3 .

7. A method for forming a composite tubular product, characterized in that: A composite cylindrical product for processing any one of claims 1 to 6, the composite cylindrical product comprising a heat-insulating layer (1), a first transition buffer structure (8), an inner wall plate (3), a radial filling structure (4) and an outer wall plate (5) arranged in sequence from the inside to the outside; The first transition buffer structure (8) is a multi-layer composite structure including a tough support layer, and the tough support layer can match the heat-insulating layer (1) and the inner wall plate (3) having different thermal expansion coefficients; The first transition buffer structure (8) comprises a first rigid connection layer (801), a first toughness support layer (802) and a second rigid connection layer (803) which are sequentially distributed from the high temperature zone to the low temperature zone; The first rigid connection layer (801) is a glass fiber felt layer, the first toughness support layer (802) is a glass fiber cloth layer, and the second rigid connection layer (803) is a glass fiber felt layer; The anti-heat-insulating layer (1) adopts a fiber-reinforced resin matrix structure; The matrix resin of the fiber-reinforced resin matrix structure is an interpenetrating composite material modified phenolic resin; The following steps are involved: Step 1: Dip-molding of heat-insulating layer: The anti-insulation layer is prepared in the mold using a vacuum impregnation process; Step 2: Lay the first transition buffer structure: Laying the materials of the first transition buffer structure layer by layer with the outer surface of the heat-insulating layer as the reference surface; Step 3: Vacuum inlet molding of inner wall panel: Using the outer surface of the first transition buffer structure as a reference surface, a vacuum introduction process is used to prepare a cylindrical component preform with an inner wall plate fixed on the outside; Step 4: Axial support structure forming: The axial support structure is prepared in the mold using the autoclave process; Step 5: Assemble the inner wall panel and axial support structure: The axial support structure is fixedly connected at a preset position of the inner wall plate to obtain a cylindrical component preform covered with the axial support structure; Step 6: Fixing the radial filling structure and radial supporting structure: The radial filling structure is bonded and fixed to the outer wall of the cylindrical preform covered with the axial support structure; the radial support structure is bonded and fixed to the outer wall of the radial filling structure, and cured and molded under vacuum to obtain a cylindrical preform having the radial filling structure and the radial support structure; Step 7: External wall panel forming: The outer wall plate is prepared by a vacuum introduction process outside the cylindrical component preform having a radial filling structure and a radial supporting structure.

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