Carbon fiber foam sandwich pultrusion profile with cavity structure and integral forming method

Abstract

The invention relates to the field of composite materials, and provides a carbon fiber foam sandwich pultrusion profile with a cavity structure and an integral forming method, and the integral forming method comprises the following steps: pre-forming the carbon fiber pultrusion profile with the cavity structure by a reinforcing material; entering a resin impregnation area, and impregnating the reinforcing material through resin; performing heating and primary curing in the heating and curing area; the preliminarily cured carbon fiber pultrusion panel with the cavity structure leaves the heating curing mold and then enters a temperature control foaming mold, and resin to be foamed is injected into a cavity of the carbon fiber pultrusion panel with the cavity structure through a built-in glue injection pipeline of a core mold for online foaming; and after online foaming is completed, post-curing is carried out, and finally cooling is carried out. According to the integrated forming method of the pultrusion profile of the carbon fiber foam sandwich with the cavity structure, integrated forming of the pultrusion profile of the carbon fiber foam sandwich with the cavity structure filled with the low-density foam material is achieved, the bonding strength of the pultrusion panel and the foam sandwich is improved, and the efficiency is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of composite materials, in particular, to a carbon fiber foam sandwich pultruded profile with cavity structure and an integrated forming method. BACKGROUND

[0002] The carbon fiber foam sandwich structure with cavity has the advantages of light weight, high stiffness, strong bearing capacity in all directions, etc. The common string structure in the field of ships is a hat-shaped string, and the hat-shaped structure profile is made of composite materials, with low-density foam sandwich in the middle.

[0003] The forming method of this structure is generally vacuum infusion forming, which includes the steps of fiber cloth laying, foam sandwich laying, overall vacuum establishment, resin infusion, curing and demolding, etc. The forming efficiency of this forming method is low, and the quality of the product is greatly affected by manual work.

[0004] Traditional pultrusion generally uses yarn impregnation to form a composite structure. Using this forming method, on the one hand, due to the single fiber arrangement direction of the pultruded product, it cannot bear stress from other directions, and its performance cannot be comparable to that of a fabric vacuum infusion formed product; on the other hand, if the method of filling the sandwich is used during pultrusion, it is very easy to cause the sandwich to break, so there are certain requirements for the density of the filled sandwich material, resulting in a large overall density of the product.

[0005] The patent with application number CN202311761468.8 in the prior art discloses a multi-cavity sandwich profile integrated forming method and system, which connects the foam core material through a mortise and tenon joint, fills the sandwich during pultrusion, and forms an integrated body through the action of the internal pressure and temperature of the mold cavity of the heated curing mold, wherein the use of the foam core material structure greatly improves the stiffness of the multi-cavity sandwich profile, makes the layer design more flexible, effectively reduces the profile wall thickness and the amount of fiber material used, and increases the sound insulation and shock absorption performance; the foam core material is connected through a mortise and tenon joint. Although this patent improves production efficiency, the pulling force of pultrusion can cause the foam core material to break, and there are certain requirements for the density of the foam core material. The low-density foam cannot be filled and integrated into the carbon fiber foam sandwich pultruded profile with cavity structure through the pultrusion process, and the adhesive strength between the pultruded profile and the foam sandwich is low. In addition, the pultruded composite material in this patent only exists in the upper and lower panels, and there is no composite material between the upper and lower panels and on both sides of the foam, which makes the bending and torsional resistance low.

[0006] In addition, traditional pultrusion is mostly carbon fiber yarn pultrusion, which has poor bearing performance and is prone to splitting, limiting its application in bearing structures.

[0007] Therefore, the present application is proposed. SUMMARY

[0008] The purpose of the present application is to provide a cavity-structured carbon fiber foam sandwich pultruded profile and an integrated forming method to solve the problem that the pulling force of the pultrusion in the prior art can cause the foam core material to break, has certain requirements for the density of the foam core material, and the internal filling of the cavity-structured carbon fiber foam sandwich pultruded profile with low-density foam cannot be achieved by the pultrusion process, and the bonding strength of the pultruded profile and the foam sandwich is low.

[0009] To achieve the above purpose, the technical scheme of the present application is as follows:

[0010] An integrated forming method of a cavity-structured carbon fiber foam sandwich pultruded profile, which integrates cavity-structured carbon fiber foam sandwich pultruded profiles by combining pultrusion and online foaming, comprises the following steps:

[0011] S1, preforming: the reinforcing material is preformed on the cavity-structured carbon fiber pultruded profile;

[0012] S2, resin impregnation: entering the resin impregnation area, the reinforcing material is impregnated with resin to make the reinforcing material fully impregnated;

[0013] S3, heating and curing: after the reinforcing material is fully impregnated with resin, the cavity-structured carbon fiber pultruded profile is formed by heating and preliminary curing in the heating and curing area, and the curing degree of preliminary curing is 90% to 95%;

[0014] S4, online foaming: after the preliminary cured cavity-structured carbon fiber pultruded profile leaves the heating and curing mold, it enters the temperature-controlled foaming mold, and at this stage, the built-in resin injection pipeline of the core mold injects the foaming resin into the cavity of the cavity-structured carbon fiber pultruded profile, the injection temperature of the foaming resin is 20 to 25℃, the online foaming is carried out in the temperature-controlled foaming mold, the online foaming temperature is 40 to 50℃, and the online foaming length is 140 to 160mm; after online foaming, post-curing is carried out, the post-curing temperature is 75 to 80℃, and the post-curing length is 150 to 200mm;

[0015] S5, cooling forming: cooling to obtain the cavity-structured carbon fiber foam sandwich pultruded profile.

[0016] Further, the preliminary curing is divided into two stages, the first stage curing temperature is 60 to 70℃, the second stage curing temperature is 80 to 90℃, the first stage curing length is 250 to 300mm, and the second stage curing length is 180 to 220mm.

[0017] Further, the reinforcing material is carbon fiber multi-axial warp knitted fabric and carbon fiber yarn, and the mass ratio of carbon fiber multi-axial warp knitted fabric to reinforcing material is more than 90%.

[0018] Furthermore, the permeability of the multiaxially oriented carbon fiber warp-woven fabric is >1E. -11 m 2 .

[0019] Furthermore, in step S2, the resin is one of unsaturated resin, polyurethane resin, epoxy resin, and phenolic resin.

[0020] Furthermore, in step S4, the built-in injection pipe is arranged in the front and rear direction through the core mold, and a heat insulation layer is provided around the built-in injection pipe.

[0021] Furthermore, a setting powder is introduced during the preparation of the multiaxial warp-woven carbon fiber fabric.

[0022] Furthermore, in step S1, preforming is performed using preforming tooling and preforming mold.

[0023] Furthermore, in step S1, before preforming, the reinforcing material is pre-impregnated after being arranged.

[0024] In a second aspect, the present invention provides a cavity-structured carbon fiber foam sandwich pultruded profile, wherein the cavity-structured carbon fiber foam sandwich pultruded profile is formed using any one of the cavity-structured carbon fiber foam sandwich pultruded profiles described in any one of the present inventions.

[0025] Compared with the prior art, the cavity-structured carbon fiber foam sandwich pultruded profile and integral molding method of the present invention have the following beneficial effects:

[0026] 1) The present invention discloses a cavity-structured carbon fiber foam sandwich pultruded profile and an integral molding method thereof, which achieves integral molding of the cavity-structured carbon fiber foam sandwich pultruded profile by filling the interior with low-density foam through a pultrusion process, wherein the foam density is 30~200 g / cm³. 3 This significantly reduces the weight of the profiles, meeting the requirements for lightweight design.

[0027] 2) The cavity-structured carbon fiber foam sandwich pultruded profile and integral molding method of the present invention firstly performs preliminary molding of the cavity-structured cap-shaped profile, with a preliminary curing degree of 90%~95%, and then performs foam molding in the cavity of the cavity-structured cap-shaped profile. The interior of the cavity-structured carbon fiber pultruded profile, which is not fully cured, has a strong interfacial bonding force with the foam directly foamed in the cavity, thereby greatly improving the bonding strength between the cavity-structured carbon fiber pultruded profile and the foam sandwich.

[0028] 3) The cavity-structured carbon fiber foam sandwich pultruded profile and integral molding method described in this invention use multi-axial warp-woven carbon fiber for pultrusion, resulting in better load-bearing performance.

[0029] 4) The carbon fiber foam sandwich pultrusion profile containing cavity structure and integrated forming method of the application combines pultrusion and online foaming to integrally form a carbon fiber foam sandwich pultrusion profile containing cavity structure, and the pultrusion and foaming are continuously performed without secondary processing, greatly improving the production efficiency, shortening the production cycle, and reducing the cost. BRIEF DESCRIPTION OF DRAWINGS

[0030] Figure 1 The flowchart of the integrated forming method of the carbon fiber foam sandwich pultrusion profile containing cavity structure according to the embodiment of the application;

[0031] Figure 2 The perspective view of the carbon fiber foam sandwich pultrusion profile containing cavity structure according to the embodiment of the application;

[0032] Figure 3 The perspective view of the mold of the carbon fiber foam sandwich pultrusion profile containing cavity structure according to the embodiment of the application;

[0033] Figure 4 The perspective view of the mold of the carbon fiber foam sandwich pultrusion profile containing cavity structure according to the embodiment of the application;

[0034] Figure 5 The top view of the mold of the carbon fiber foam sandwich pultrusion profile containing cavity structure according to the embodiment of the application.

[0035] BRIEF DESCRIPTION OF DRAWINGS

[0036] 1, preforming tooling; 2, preforming mold; 3, glue injection box; 4, heating and curing mold. DETAILED DESCRIPTION

[0037] In order to make the technical means and purposes and effects of the application easy to understand, the embodiments of the application will be described in detail below in combination with specific drawings.

[0038] It should be noted that all directional and positional indications in the application, such as "up", "down", "left", "right", "front", "back", "vertical", "horizontal", "inner", "outer", "top", "low", "transverse", "longitudinal", "center", etc., are only used to explain the relative positional relationship, connection condition, etc. between components in a certain state (as shown in the drawings), and are only for the convenience of describing the application, and are not required to construct and operate the application in a particular orientation, and therefore cannot be understood as a limitation on the application. In addition, the description of "first", "second", etc. in the application is only for the purpose of description, and cannot be understood as indicating or implying the relative importance of the indicated technical features or implicitly indicating the number of the indicated technical features.

[0039] In the description of the present application, unless otherwise explicitly specified and limited, the terms "mounting", "connection", "connecting" should be understood in a broad sense, for example, can be fixed connection, can also be detachable connection, or integrally connected, can be mechanical connection, can be directly connected, can be indirectly connected through an intermediate medium, and can be internal communication of two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0040] In the description of the present application, the description of the terms "one embodiment", "some embodiments", "exemplary embodiment", "example", "specific example", or "some examples" means that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present application. In the present application, the exemplary description of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0041] The present application will be described in detail below with reference to the accompanying drawings and in conjunction with the embodiments.

[0042] The existing technology has the problem that the pulling force of pultrusion causes the foam core material to break, and has certain requirements on the density of the foam core material, and the low-density foam cannot be filled inside the cavity-structure carbon fiber foam sandwich pultruded profile through the pultrusion process, and the bonding strength between the pultruded profile and the foam sandwich is low. In addition, the pultruded composite material in the patent only exists in the upper and lower panels, and there is no composite material between the upper and lower panels and on both sides of the foam, which makes the bending and torsional resistance low.

[0043] To solve the above technical problems, in the present application, an integrated forming method of a cavity-structure carbon fiber foam sandwich pultruded profile is provided, as shown in Figures 1-2 The integrated forming method is combined with pultrusion and online foaming to integrally form a cavity-structure carbon fiber foam sandwich pultruded profile, and the cavity-structure carbon fiber foam sandwich pultruded profile contains at least one cavity structure.

[0044] The integrated forming method comprises the following steps:

[0045] S1, preforming: after the reinforcing material is arranged, the cavity-structure carbon fiber pultruded profile is preformed;

[0046] S2, resin impregnation: entering the resin impregnation area, the reinforcing material is impregnated with resin to make the reinforcing material fully impregnated;

[0047] S3, heating and curing: after the reinforcing material is fully impregnated with resin, the cavity-structure carbon fiber pultruded profile is formed by heating and preliminary curing in the heating and curing area, and the curing degree of the preliminary curing is 90%~95%.

[0048] S4. Online Foaming: After the pre-cured pultruded carbon fiber profile with cavity structure leaves the heating curing mold 4, it enters the temperature-controlled foaming mold. During this stage, the resin to be foamed is injected into the cavity of the pultruded carbon fiber profile with cavity structure through the built-in injection pipe of the core mold. The injection temperature of the resin to be foamed is 20~25℃. Online foaming is carried out in the temperature-controlled foaming mold at a temperature of 40~50℃ and a length of 150mm. After online foaming is completed, post-curing is carried out at a temperature of 75~80℃ and a length of 150~200mm.

[0049] S5. Cooling and molding: Cooling is performed to obtain a cavity-structured carbon fiber foam sandwich pultruded profile.

[0050] This invention discloses an integral molding method for a cavity-structured carbon fiber foam sandwich profile. Steps S1 to S5 are interconnected and highly synergistic, offering the following beneficial effects:

[0051] 1) The present invention discloses an integral molding method for a cavity-structured carbon fiber foam sandwich pultruded profile. This method first uses a pultrusion process to initially solidify and form a cavity-structured carbon fiber shell, and then injects foaming resin into the inner cavity using the same pultrusion process. This not only avoids the direct effect of traction force on the foam, fundamentally solving the breakage problem, but also achieves integral molding of the cavity-structured carbon fiber foam sandwich pultruded profile filled with low-density foam, with a foam density of 30~200 g / cm³. 3 This significantly reduces the weight of the profiles, meeting the requirements for lightweight design.

[0052] 2) The integral molding method of the cavity-structured carbon fiber foam sandwich pultruded profile of the present invention firstly performs preliminary molding of the cavity-structured cap-shaped structure, with a preliminary curing degree of 90%~95%. At this time, the carbon fiber shell has a certain rigidity to maintain the cavity structure, and the surface activity of the incompletely cured material is high. Then, foam molding is performed in the cavity of the cavity-structured cap-shaped structure. The interior of the cavity-structured carbon fiber pultruded profile and the foam directly foamed in the cavity have a strong interfacial bonding force, thereby greatly improving the bonding strength between the cavity-structured carbon fiber pultruded profile and the foam sandwich.

[0053] 3) The integral molding method of the cavity structure carbon fiber foam sandwich pultruded profile described in this invention uses multi-axial warp braided carbon fiber for pultrusion, which has better load-bearing performance.

[0054] 4) The method for integrally forming the carbon fiber foam sandwich pultrusion profile with a cavity structure, the injection temperature of the foaming resin is 20-25℃, the online foaming is carried out in the temperature control foaming mold at 40-50℃, the length of the online foaming is 140-160mm, and the post-curing is carried out at 75-80℃, and the length of the post-curing is 150-200mm; on the one hand, the uniform expansion and sufficient curing of the foam in the controlled environment are ensured; on the other hand, the interface between the foam and the outer wall of the carbon fiber pultrusion profile with a cavity structure is fully crosslinked, and the overall mechanical properties are improved.

[0055] 5) The method for integrally forming the carbon fiber foam sandwich pultrusion profile with a cavity structure, the pultrusion and online foaming are combined and integrally formed into the carbon fiber foam sandwich pultrusion profile with a cavity structure, the pultrusion and foaming are continuously carried out, and secondary processing is not needed; while the excellent mechanical properties are ensured, the efficient and stable continuous production is realized, the production efficiency is greatly improved, the production cycle is shortened, and the cost is reduced.

[0056] 6) The method for integrally forming the carbon fiber foam sandwich pultrusion profile with a cavity structure, a full-closed continuous composite material shell is formed instead of only upper and lower panels, and the bending and torsion resistance of the carbon fiber foam sandwich pultrusion profile with a cavity structure is more excellent.

[0057] As shown in Figures 3-5 The mold used in the method for integrally forming the carbon fiber foam sandwich pultrusion profile with a cavity structure includes a preforming tool 1, a preforming mold 2, a glue injection box 3, a heating and curing mold 4, and a temperature control foaming mold (not shown in the figure).

[0058] Specifically, the preliminary curing is carried out in two stages, the first stage curing temperature is 60-70℃, the second stage curing temperature is 80-90℃, the first stage curing length is 250-300mm, and the second stage curing length is 180-220mm.

[0059] The preliminary curing is controlled in two stages of temperature, and the crosslinking degree is gradually improved.

[0060] In addition, the traditional pultrusion forming is mainly carbon fiber yarn pultrusion, the bearing performance is poor and the splitting is easy to occur, which limits the application in the bearing structure.

[0061] Specifically, the reinforcing material is carbon fiber multi-axial warp knitted fabric and carbon fiber yarn, and the mass ratio of the carbon fiber multi-axial warp knitted fabric in the reinforcing material is more than 90%.

[0062] The carbon fiber multi-axial warp knitted fabric gives the profile higher strength, rigidity, impact resistance and bearing performance in all directions. The mass ratio of the carbon fiber multi-axial warp knitted fabric in the reinforcing material is more than 90%, and the bearing performance is more excellent; the carbon fiber yarn supplements the local rigidity and optimizes the mechanical property distribution.

[0063] Specifically, the permeability of the carbon fiber multi-axial warp-knitted fabric is >1E -11 m 2 .

[0064] The high-permeability fabric ensures fast resin infiltration and reduces defects.

[0065] More specifically, when the permeability of the carbon fiber multi-axial warp-knitted fabric is >2.5E -11 m 2 , resin impregnation is performed using a resin impregnation tank; when the permeability of the carbon fiber multi-axial warp-knitted fabric is 1~2.5E -11 m 2 , resin injection is performed using a closed mold resin injection box 3.

[0066] Specifically, in step S2, the resin is one of unsaturated resin, polyurethane resin, epoxy resin and phenolic resin.

[0067] Specifically, in step S4, the built-in resin injection pipeline is arranged in the through direction of the core mold, and a thermal insulation layer is arranged around the built-in resin injection pipeline to prevent foaming during the transportation of the core mold.

[0068] In step S2, when resin injection is performed using a closed mold resin injection box 3, a resin injection runner is arranged under each layer of carbon fiber multi-axial warp-knitted fabric before the fabric enters the resin injection box 3, so that the carbon fiber multi-axial warp-knitted fabric can be fully contacted with the resin before entering the resin injection unit.

[0069] In step S4, the foaming foam density is controlled to be 30~200g / cm 3 by controlling the amount of foaming agent, and the foaming cavity in the temperature-controlled foaming mold is a closed mold free foaming with a carbon fiber foam sandwich pultrusion profile as the outer cavity.

[0070] The foaming resin is a polyurethane system, specifically a combination of isocyanate and polyester polyol composed of AB materials, and the A:B material ratio is 1:1.2.

[0071] The foaming system is composed of water and a low-boiling foaming agent, and the low-boiling foaming agent is HCFC or F11.

[0072] Specifically, the empirical formula for controlling the foaming foam density ρ by controlling the amount of foaming agent w under 100 parts of B material is:

[0073] ρ=101.118 / (w+0.1394);

[0074] wherein ρ is the foam density and w is the amount of foaming agent.

[0075] The formula can be calculated to obtain different polyurethane rigid foam density by adding different amounts of foaming system to 100 parts of B material.

[0076] If 30kg / m 3 density foam is to be obtained, 3.23 parts of foaming agent need to be added corresponding to 100 parts of B material; if 50kg / m 3 density foam is to be obtained, 1.88 parts of foaming agent need to be added corresponding to 100 parts of B material; if 150kg / m 3 density foam is to be obtained, 0.53 parts of foaming agent need to be added corresponding to 100 parts of B material; if 200kg / m 3 density foam is to be obtained, 0.366 parts of foaming agent need to be added corresponding to 100 parts of B material.

[0077] In pultrusion, the speed of injecting foaming liquid can be considered consistent with the pultrusion speed. If the inner cavity section of the carbon fiber pultrusion profile with cavity structure is 200*100mm, when 30kg / m 3 density foam is to be obtained, the material system ratio needed is A:B:w=83.3:100:3.23, and the weight of the material in unit volume used is 30kg*(200*100) / 1000*1000=0.6kg. The material ratio used to fill the cavity can be obtained by distributing 0.6kg of material according to the ratio of A:B:w=83.3:100:3.23.

[0078] Similarly, if the inner cavity section of the carbon fiber pultrusion profile with cavity structure is 200*100mm, when 200kg / m 3 density foam is to be obtained, the material system ratio needed is A:B:w=83.3:100:0.366, and the weight of the material in unit volume used is 200kg*(200*100) / 1000*1000=4kg. The material ratio used to fill the cavity can be obtained by distributing 4kg of material according to the ratio of A:B:w=83.3:100:0.366.

[0079] In step S6, the cooling section length is 300mm, and gradient temperature control water cooling is used to obtain the carbon fiber foam sandwich pultrusion profile with cavity structure.

[0080] The cooling section uses gradient temperature control water cooling to reduce internal stress and prevent profile warping.

[0081] When the wall thickness of the outer wall of the carbon fiber pultrusion profile with cavity structure is 1-3mm, the pultrusion rate v satisfies: 0.3≤v<0.4m / min; when the wall thickness is 4-6mm, the pultrusion rate v satisfies: 0.4≤v<0.5m / min.

[0082] In addition, in the use of fabric pultrusion process, there are multi-axial fabric impregnation difficulties, fabric deformation, wrinkles, twists and other problems, resulting in pultrusion product deformation, resin content uneven, etc. When forming wide width cavity structure, it is particularly difficult.

[0083] Specifically, a setting powder is introduced in the process of preparing the carbon fiber multi-axial warp-knitted fabric, and the setting powder is a thermoplastic powder.

[0084] The setting powder is a thermoplastic powder, which will soften and have certain viscosity at 60-80℃. The preforming mold 2 has certain compressibility, and the carbon fiber multi-axial warp-knitted fabric is preliminarily compacted, and the hat-shaped structure with cavity is preformed. The carbon fiber multi-axial warp-knitted fabric is preformed in the preforming mold 2 to obtain the final desired fabric form.

[0085] More specifically, the thermoplastic powder is at least one of nylon modified epoxy resin, nitrile rubber toughened epoxy, thermoplastic modified PET and thermoplastic nylon.

[0086] The mesh number of the setting powder is 100-120.

[0087] If the mesh number is too low, the powder particles are too large, and it is difficult to uniformly adhere to the fiber bundle surface, which may form local accumulation, affect the subsequent resin infiltration, and even crush the fibers during preforming; if the mesh number is too high, the superfine powder is easy to produce dust, pollute the environment and cause great loss; at the same time, the superfine powder may completely embed in the deep part of the fiber bundle, and only melt in the fiber during preheating, which cannot form effective bonding points between different layers of fabric or between fabric and mold, reducing the pre-setting effect.

[0088] The powder particle size of 100-120 mesh is moderate, which has the following advantages:

[0089] 1. It can be stably attached to the fiber surface and bundle, and also has sufficient surface adhesion after heating to achieve effective setting;

[0090] 2. The influence on resin flow is minimized, which ensures that the resin can still flow relatively smoothly and infiltrate the fibers in step S2, avoiding dry spots or poor infiltration caused by the addition of setting agent.

[0091] 3. The powder in this particle size range can achieve rapid and uniform melting at a preheating temperature of 60-80℃.

[0092] Specifically, the amount of setting powder attached to the surface of each layer of carbon fiber multi-axial warp-knitted fabric is 3-5g / m 2 .

[0093] If the amount is too low, the bonding points are insufficient, the setting force is weak, and the fabric cannot be effectively constrained, and the anti-deformation effect cannot be achieved; if the amount is too high, the excess setting powder will form a continuous film or a large piece of bonding area on the surface of the fabric after melting, which will not only seriously hinder the subsequent resin impregnation of the fiber, leading to a large area of poor glue area in the composite material, greatly damaging the mechanical properties; and will lose the flexibility of the fabric, making the fabric become rigid before entering the mold, difficult to fit the complex curved surface of the mold cavity, especially prone to bridging or wrinkling at sharp corners.

[0094] 3~5 g / m² of the amount has the following advantages:

[0095] I. Provide sufficient bonding strength to resist traction deformation:

[0096] II. Achieve "point bonding" rather than "surface coverage", while fixing the fiber position, the permeability and flexibility of the fabric are maximized.

[0097] III. Will not have a negative impact on the final mechanical properties of the profile.

[0098] Specifically, in step S1, preforming is performed using a preforming tool 1 and a preforming mold 2.

[0099] The combination of the preforming tool 1 and the preforming mold 2 gradually compacts and sets the fabric; ensures that the carbon fiber multi-axial warp fabric is flat, non-deformable and wrinkle-free during the traction process, maintains the stability of the cavity shape, and avoids fiber twisting or uneven resin distribution; this is particularly important for wide-width cavity-containing structures.

[0100] Specifically, in step S1, the preforming mold 2 is initially preheated, and the initial preheating temperature is 60~80℃.

[0101] This setting causes the setting powder in the carbon fiber multi-axial warp fabric to melt, causing the carbon fiber multi-axial warp fabric to be pre-set in the preforming mold 2, resulting in the final desired fabric form.

[0102] Specifically, an infrared heating jacket is provided outside the preforming mold 2.

[0103] The infrared heating jacket can control the temperature of the preforming mold 2 to be 60~80℃.

[0104] More specifically, in step S1, before preforming, the reinforced material is arranged and then enters the impregnation tank or injection box 3 to complete the pre-impregnation.

[0105] Specifically, the areal density of the carbon fiber multi-axial warp fabric is 600~800 g / m 2 .

[0106] The carbon fiber multi-axial warp-knitted fabric can be a 90° and ±45° three-axial fabric, the carbon fiber multi-axial warp-knitted fabric can also be a 0°, 90° and ±45° four-axial fabric, and the carbon fiber multi-axial warp-knitted fabric can also be a 0° single-axial fabric.

[0107] The wall thickness is 2-4 mm, and the areal density is 600-800 g / m 2 The number of fabric layers is 3-5 layers, and according to the actual design, three-axial fabric, four-axial fabric and 0° single-axial fabric can be used. In the product profile, the position containing an acute angle of <45° is difficult to fill with fabric, and it can also cause the fabric to stack and block the mold at a narrow place, so the filling of the carbon fiber yarn is performed in this area. The number of filling yarns is determined by the cross-sectional area of the filled area and the yarn linear density.

[0108] More specifically, in step S2, the glue injection channel is a glue injection hole, after entering the glue injection box 3, the glue injection hole size on the glue injection box 3 is 8 mm, the glue injection points are arranged on the upper and lower single-layer fabrics from the fabric width edges, the interval between adjacent two glue injection holes is 20 mm, and the internal pressure of the glue injection box 3 is 0.05-0.08 MPa, which can not only avoid causing deformation of the fabric, but also ensure complete infiltration of the fabric in the glue injection box 3.

[0109] Example 1

[0110] The embodiment provides an integrated forming method of a carbon fiber foam sandwich pultrusion profile containing a cavity structure, the integrated forming method is combined with pultrusion and online foaming to integrally form a carbon fiber foam sandwich pultrusion profile containing a cavity structure, and the carbon fiber foam sandwich pultrusion profile containing a cavity structure contains one cavity structure.

[0111] The integrated forming method comprises the following steps:

[0112] S1, preforming: after the reinforcing material is arranged, the carbon fiber pultrusion profile containing a cavity structure is preformed;

[0113] S2, resin impregnation: entering a resin impregnation area, the reinforcing material is impregnated with resin, so that the reinforcing material is fully infiltrated;

[0114] S3, heating and curing: after the reinforcing material is fully infiltrated with the resin, the reinforcing material is heated and preliminarily cured in a heating and curing area to form the carbon fiber pultrusion profile containing a cavity structure, and the curing degree of the preliminary curing is 95%;

[0115] S4, online foaming: the preliminary cured carbon fiber pultrusion profile with cavity structure leaves the heating and curing mold 4 and enters the temperature-controlled foaming mold. In this stage, the built-in glue injection pipeline of the core mold injects the foaming resin into the cavity of the carbon fiber pultrusion profile with cavity structure. The injection temperature of the foaming resin is 20℃. The online foaming is performed in the temperature-controlled foaming mold. The temperature of the online foaming is 50℃. The length of the online foaming is 150mm. After the online foaming is completed, post-curing is performed. The temperature of the post-curing is 80℃. The length of the post-curing is 180mm.

[0116] S5, cooling forming: cooling is performed to obtain the carbon fiber foam sandwich pultrusion profile with cavity structure.

[0117] The wall thickness of the outer wall of the carbon fiber pultrusion profile with cavity structure is 4mm. The pultrusion rate v is 0.4m / min.

[0118] The setting can prevent the product from deforming due to incomplete curing in the mold.

[0119] Specifically, the preliminary curing is performed in two stages. The first-stage curing temperature is 60℃. The second-stage curing temperature is 85℃. The first-stage curing length is 300mm. The second-stage curing length is 220mm.

[0120] Specifically, in step S2, the resin is an unsaturated resin.

[0121] More specifically, in step S2, the resin is a vinyl resin.

[0122] More specifically, in step S2, the resin system is a low-temperature / normal-temperature curing vinyl resin formula. The vinyl resin main agent, the oxidation-reduction curing system, 2% MEKP / CHP (methyl ethyl ketone peroxide / cumene hydroperoxide) as an oxidizing agent + 0.2% DMA (N, N-dimethyl aniline) as a reducing agent are selected to ensure that the reaction system has activity at a lower temperature. At the same time, 0.5% organic cobalt salt complex solution (Co: 6%) is added as an accelerator.

[0123] The vinyl resin formula is highly matched with the first-stage curing temperature 70℃ and the second-stage curing temperature 85℃ of the preliminary curing, and exhibits good design synergy.

[0124] Among them, 2% MEKP / CHP, 0.2% DMA, and 0.5% organic cobalt salt complex solution are all relative to the weight of the vinyl resin main agent.

[0125] Specifically, the reinforcing material is a carbon fiber multi-axial warp knit and a carbon fiber yarn. In this embodiment, the mass ratio of the carbon fiber multi-axial warp knit to the reinforcing material is 92%.

[0126] More specifically, in the embodiment, when the permeability of the carbon fiber multi-axial warp-knitted fabric is 2E -11 m 2 , closed mold injection is used to inject resin into the injection box 3.

[0127] Specifically, in step S2, when closed mold injection is used to inject resin into the injection box 3, an injection flow channel is arranged under each layer of carbon fiber multi-axial warp-knitted fabric before the carbon fiber multi-axial warp-knitted fabric enters the injection box 3, so that the carbon fiber multi-axial warp-knitted fabric can be fully contacted with the resin before entering the resin injection unit.

[0128] Specifically, the injection flow channel is an injection hole, and after entering the injection box 3, the size of the injection hole on the injection box 3 is 8 mm, the injection points are arranged on the upper and lower edges of the width of the single-layer fabric, the interval between adjacent two injection holes is 20 mm, and the internal pressure of the injection box 3 is 0.07 MPa.

[0129] Specifically, in the embodiment, the foaming resin is a polyurethane system, specifically, an isocyanate and polyester polyol combined material composed of AB materials, the A:B material ratio is 1:1.2; the foaming system is composed of water and a low-boiling foaming agent, the low-boiling foaming agent is HCFC, 3.23 parts of foaming agent are added corresponding to 100 parts of B material, and a foaming foam density of 30 g / cm 3 .

[0130] Specifically, in step S4, the built-in resin injection pipeline is arranged in the through direction of the core mold, and a thermal insulation layer is arranged around the built-in resin injection pipeline.

[0131] In step S4, the temperature-controlled foaming mold has a temperature control function, and the mold temperature reaches the foam injection temperature and the online foaming temperature.

[0132] In step S5, the cooling section length is 300 mm, and gradient temperature control water cooling is used to obtain a carbon fiber foam sandwich pultrusion profile with a cavity structure.

[0133] Specifically, a setting powder is introduced in the process of preparing the carbon fiber multi-axial warp-knitted fabric, and the setting powder is a thermoplastic powder.

[0134] The thermoplastic powder is a nylon modified epoxy resin.

[0135] The mesh number of the setting powder is 110 meshes, and the amount of setting powder attached to the surface of each layer of fabric is 4 g / m 2 .

[0136] Specifically, in step S1, preforming is performed by using a preforming tool 1 and a preforming mold 2.

[0137] Specifically, in step S1, the preforming mold 2 is preliminarily preheated, and the temperature of the preliminary preheating is 80°C.

[0138] Specifically, the areal density of the multiaxially oriented carbon fiber braided fabric is 800 g / m². 2 .

[0139] The outer wall thickness of the cavity-structured carbon fiber pultruded profile is 4 mm, and the areal density is 800 g / m³. 2 The fabric has four layers, and the carbon fiber multiaxial warp-knitted fabric is a four-axis fabric with 0°, 90° and ±45°.

[0140] Carbon fiber yarn is used to fill areas with acute angles less than 45° in the product outline. The amount of carbon fiber yarn used is determined by the cross-sectional area of ​​the filled area and the linear density of the yarn.

[0141] Example 2

[0142] In this embodiment, unlike in Embodiment 1, the degree of initial curing is 90%.

[0143] Specifically, in step S2, the resin is epoxy resin.

[0144] More specifically, in step S2, the resin system is a low-temperature / room-temperature curing epoxy resin formulation: bisphenol A type epoxy resin as the main agent, and the oxidation-reduction curing system uses 30% polyamide resin as the curing agent + 1% BDMA (benzyl dimethylamine) as the accelerator to ensure that it has reactivity at a lower temperature.

[0145] Among them, 30% polyamide resin as curing agent and 1% BDMA are relative to the weight of bisphenol A type epoxy resin main agent.

[0146] Specifically, the mass ratio of multiaxially oriented carbon fiber braided fabric to reinforcing material is 93%.

[0147] Specifically, the initial curing is carried out in two stages: the first stage curing temperature is 60℃, the second stage curing temperature is 90℃, the first stage curing length is 250mm, and the second stage curing length is 180mm.

[0148] Specifically, the injection temperature of the resin to be foamed is 25℃, and online foaming is carried out in a temperature-controlled foaming mold at a temperature of 45℃.

[0149] Specifically, the post-curing temperature is 75℃.

[0150] In this embodiment, 1.88 parts of foaming agent were added for every 100 parts of material B, resulting in a foam density of 50 g / cm³. 3 .

[0151] Specifically, the pre-forming mold 2 is preheated at a temperature of 60°C.

[0152] Specifically, the areal density of the carbon fiber multi-axial warp fabric is 600 g / m 2 .

[0153] The carbon fiber multi-axial warp fabric can be a 90° and ±45° three-axial fabric.

[0154] The sizing powder has a mesh number of 100 mesh, and the amount of the sizing powder adhered to the surface of each layer of fabric is 5 g / m 2 .

[0155] Example 3

[0156] In this example, different from Example 1, specifically, the curing degree of the preliminary curing is 92%.

[0157] Specifically, in step S2, the resin is a polyurethane resin.

[0158] More specifically, in step S2, the polyurethane resin system formula is that the polyol material and the isocyanate material are in a mass ratio of 100:135, wherein the polyol material is a polyester polyol, and the isocyanate material is MDI (diphenyl methane diisocyanate).

[0159] Specifically, the mass ratio of the carbon fiber multi-axial warp fabric in the reinforcing material is 91%.

[0160] Specifically, the preliminary curing is performed in two stages, the first-stage curing temperature is 65°C, the second-stage curing temperature is 80°C, the first-stage curing length is 280 mm, and the second-stage curing length is 200 mm.

[0161] Specifically, the injection temperature of the to-be-foamed resin is 22°C, and the on-line foaming is performed in a temperature-controlled foaming mold, and the on-line foaming temperature is 40°C.

[0162] Specifically, the post-curing temperature is 78°C.

[0163] In this example, 0.535 parts of the foaming agent are added corresponding to 100 parts of the B material, and a foamed foam density of 150 g / cm 3 .

[0164] Specifically, the preliminary preheating is performed in the preforming mold 2, and the preliminary preheating temperature is 70°C.

[0165] Specifically, the areal density of the carbon fiber multi-axial warp fabric is 700 g / m 2 .

[0166] The carbon fiber multi-axial warp fabric is a 0° single-axial fabric.

[0167] The sizing powder has a mesh number of 120 mesh, and the amount of the sizing powder adhered to the surface of each layer of fabric is 3 g / m2 .

[0168] Comparative Example 1

[0169] In this embodiment, different from Example 1, vacuum infusion molding is adopted, and the steps include laying of fiber cloth, laying of foam core, overall vacuum establishment, infusion of resin, curing and demolding, and other steps. Since the specific steps of vacuum infusion molding are prior art, they are not described here.

[0170] Performance test

[0171] The carbon fiber foam core profiles with cavity structure formed by using Examples 1-3 and Comparative Example 1 are subjected to performance test, and the results are shown in Table 1.

[0172] Table 1 Performance test

[0173]

[0174] As can be seen from Table 1, by comparing Example 1 with Comparative Example 1, it can be seen that by using the integrated molding method of the carbon fiber foam core pultrusion profile with cavity structure according to the present application, firstly, the bonding strength of the profile and the foam core is improved, secondly, not only the ultimate bearing performance of the carbon fiber foam core pultrusion profile with cavity structure is improved, but also it can bear greater load; it also has excellent bending stiffness; thirdly, the tensile strength, bending strength and interlaminar shear strength of the outer wall of the profile are improved.

[0175] Although the present application is disclosed as above, the present application is not limited thereto. Any person skilled in the art, without departing from the spirit and scope of the present application, can make various changes and modifications, therefore the protection scope of the present application should be subject to the scope defined by the claims.

Claims

1. A method of integrally forming a cavitied-structure carbon fiber foam sandwich pultrusion profile, characterized by, The integrated forming method is an integrated forming method for integrally forming a carbon fiber foam sandwich pultrusion profile with a cavity structure by combining pultrusion and online foaming, and the integrated forming method comprises the following steps: S1, preforming: after the reinforcing material is arranged, the carbon fiber pultrusion profile with a cavity structure is preformed; S2, resin impregnation: entering the resin impregnation area, the reinforcing material is impregnated with resin, so that the reinforcing material is fully impregnated; S3, heating and curing: after the reinforcing material is fully impregnated with resin, the carbon fiber pultrusion profile with a cavity structure is preliminarily cured by heating in the heating and curing area, and the curing degree of the preliminary curing is 90%-95%; S4, online foaming: after the preliminarily cured carbon fiber pultrusion profile with a cavity structure leaves the heating and curing mold (4), it enters the temperature control foaming mold, at this stage, the built-in glue injection pipeline of the core mold injects the foaming resin into the cavity of the carbon fiber pultrusion profile with a cavity structure, the injection temperature of the foaming resin is 20-25℃, the online foaming is carried out in the temperature control foaming mold, the temperature of the online foaming is 40-50℃, and the length of the online foaming is 140-160mm; after the online foaming is completed, post-curing is carried out, the temperature of the post-curing is 75-80℃, and the length of the post-curing is 150-200mm; S5, cooling forming: cooling is carried out to obtain the carbon fiber foam sandwich pultrusion profile with a cavity structure.

2. A method of integrally forming a pultruded profile of a carbon fibre foam sandwich containing a cavity according to claim 1, characterised in that, The preliminary curing is carried out in two stages, the first stage curing temperature is 60-70℃, the second stage curing temperature is 80-90℃, the first stage curing length is 250-300mm, and the second stage curing length is 180-220mm.

3. A method of integrally forming a pultruded profile of a carbon fibre foam sandwich according to claim 1, characterised in that, The reinforcing material is a carbon fiber multi-axial warp knitted fabric and a carbon fiber yarn, and the mass ratio of the carbon fiber multi-axial warp knitted fabric in the reinforcing material is more than 90%.

4. A method of integrally forming a pultruded profile of a carbon fibre foam sandwich according to claim 3, characterised in that, The carbon fiber multi-axial warp knit has a permeability > 1E -11 m 2 .

5. A method of integrally forming a pultruded profile of a carbon fibre foam sandwich according to claim 1, characterised in that, In step S2, the resin is one of unsaturated resin, vinyl ester resin and phenolic resin.

6. A method of integrally forming a pultruded profile of a carbon fibre foam sandwich according to claim 1, characterised in that, In step S4, the built-in glue injection pipeline is arranged in the front and rear directions of the core mold, and a thermal insulation layer is arranged around the built-in glue injection pipeline.

7. A method of integrally forming a pultruded profile of a carbon fibre foam sandwich according to claim 3, characterised in that, A setting powder is introduced in the process of preparing the carbon fiber multi-axial warp knitted fabric.

8. A method of integrally forming a pultruded profile of a carbon fibre foam sandwich according to claim 1, characterised in that, In step S1, the preforming is carried out by using a preforming tool (1) and a preforming mold (2).

9. A method of integrally forming a pultruded profile of a carbon fibre foam sandwich according to claim 1, characterised in that, In step S1, before preforming, the reinforcing material is arranged and then enters the pre-impregnation area.

10. A cavitating carbon fibre foam sandwich pultrusion, characterised in that, The carbon fiber foam sandwich pultrusion profile with a cavity structure is formed by using the integrated forming method of any one of claims 1-9.

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