Integrated forming method for carbon fiber structural part of sunken opening frame

Abstract

The invention relates to the technical field of forming of composite material force-bearing structural parts, in particular to an integral forming method for a carbon fiber structural part of a sunken opening frame. The invention provides an integrated forming method for a carbon fiber structural part of a sunken opening frame. The integrated forming method comprises the steps that overall layering is conducted, skin fibers are turned over multiple times, and the folded skin fibers are used for layering the opening frame in a layered mode; the sunken opening frame, the reinforcing area and the skin are formed in a layering mode, and a product obtained after layering is completed is subjected to mold pre-pressing and skin shape maintaining and curing; curing and forming: discharging the cured product out of the furnace, and removing the process skin for maintaining the shape on the outer side; demolding engineering, wherein the product is taken down from the mold through a demolding tool; and detecting and processing the end face and the opening of the product. According to the technical scheme, the sunken type opening frame structure carbon fiber shell is integrally formed, the overall continuity of fibers is guaranteed to the maximum extent, and the bearing capacity of the shell structure is improved.

Description

Technical Field

[0001] The present disclosure relates to the technical field of composite material load-bearing structural member molding, and in particular to a method for integrally molding a carbon fiber structural member of a sunken mouth frame. Background Art

[0002] The sunken opening frame of the carbon fiber composite shell supports the overall strength and has certain load-bearing requirements. If a bonding process is used here, where the shell and frame are formed separately and then bonded together, the structural strength will be low, failing to meet product design requirements and also unable to guarantee the internal quality of the product. In addition, due to the excessively large and dense openings in the final product, if all openings are machined after integral molding, the internal quality of the product will be damaged and certain processing stresses will cause product deformation, thereby affecting the contour accuracy. Summary of the Invention

[0003] The present disclosure aims to solve at least one of the technical problems existing in the prior art or related art.

[0004] To this end, the present disclosure provides a method for integrally forming a carbon fiber structural member of a sunken mouth frame, characterized by comprising:

[0005] Overall layering, folding the skin fibers multiple times, and using the folded skin fibers to layer the opening frame in layers;

[0006] The sunken frame, reinforcement area and skin layer are formed, and after the layer is laid, the product is pre-pressed in the mold and the skin is dimensional cured;

[0007] Curing and molding, the product is taken out of the oven after curing, and the outer dimensional process skin is removed;

[0008] Demolding process: using demoulding tools to remove the product from the mold;

[0009] Inspection and processing, processing product end faces and openings, etc.

[0010] In a feasible embodiment, the mold pre-pressing adopts vacuum hot pressing, wherein the hot pressing temperature is set to 100° C. to 130° C., the process pressure is increased to 0.6 MPa, and the pressure increase and release rate is 20 KPa / min.

[0011] In a feasible implementation manner, mechanical pressurization is performed on the sunken opening frame before the vacuum hot pressing.

[0012] In a feasible embodiment, the temperature rise regime for the dimensional curing of the skin is 200°C to 240°C, the whole temperature rise and fall rate is 60±5°C / h, and the process pressure is increased to 0.6MPa.

[0013] In a feasible embodiment, the process pressurization rate is 20 KPa / min, and the pressure relief rate is 10 KPa / min.

[0014] In a feasible embodiment, the multiple folding of the skin fibers is divided into 0° fiber folding and 45° fiber folding.

[0015] In a feasible embodiment, when the skin fibers are folded from the end frame to the skin, the folded overlapping width is less than or equal to 1 mm.

[0016] In a feasible embodiment, the gap between the joints of the multiple folded skin fibers is set to 50±10 mm.

[0017] In a feasible embodiment, the gaps in the joints are filled with prepreg.

[0018] In a feasible embodiment, the cutting direction of the skin fiber folded layer is consistent with the fiber direction.

[0019] The above description is only an overview of the technical solution provided by the present disclosure. In order to more clearly understand the technical means of the present disclosure, it can be implemented in accordance with the contents of the specification. In order to make the above and other features and effects of the present disclosure more obvious and easy to understand, the following specifically lists the implementation methods of the present disclosure. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the present disclosure and, together with the description, serve to explain the principles of the present disclosure.

[0021] In order to more clearly illustrate the embodiments of the present disclosure or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0022] Various other advantages and benefits will become apparent to those skilled in the art upon reading the detailed description of the exemplary embodiments below. The accompanying drawings are for illustration purposes only and are not to be considered limiting of the present application. Throughout the accompanying drawings, the same reference symbols denote the same components. In the accompanying drawings:

[0023] Figure 1 This is a schematic diagram of the structure of the present disclosure with a fiber direction of 45°;

[0024] Figure 2 This is a schematic diagram of the structure of the 0° fiber direction disclosed in the present invention.

[0025] in, Figure 1and Figure 2 The corresponding relationship between the reference numerals and component names is as follows:

[0026] 1-Fiber direction. DETAILED DESCRIPTION

[0027] In order to more clearly understand the above-mentioned objectives, features and advantages of the present disclosure, the scheme of the present disclosure will be further described below. It should be noted that the embodiments of the present disclosure and the features therein can be combined with each other in the absence of conflict.

[0028] In the following description, many specific details are set forth to facilitate a full understanding of the present disclosure, but the present disclosure may also be implemented in other ways different from those described herein; it is obvious that the embodiments in the specification are only part of the embodiments of the present disclosure, rather than all of the embodiments.

[0029] Currently, the sunken opening frame of a carbon fiber composite shell supports the overall strength and has certain load-bearing requirements. If a bonding process is used here, where the shell and frame are formed separately and then bonded together, the structural strength will be low, failing to meet product design requirements and also unable to guarantee the internal quality of the product. In addition, since the final product has too large and too dense openings, if all openings are machined after integral molding, the internal quality of the product will be damaged and certain processing stresses will cause product deformation, thereby affecting the contour.

[0030] Based on this, the embodiment of the present disclosure provides an integrated molding method for a carbon fiber structural part of a sunken mouth frame, in which the skin fibers are folded multiple times, and the folded skin fibers are used to lay the mouth frame in layers to ensure the continuity of the internal fibers during product preparation, thereby improving the bearing capacity of the structural compartment and the integrity of the product shape, and performing dimensional curing through the process skin. A process skin with less rigidity is used instead of a rigid mold, which can better adhere to the outer surface of the product during the curing process and avoid outer contour deviation caused by assembly interference caused by the rigid mold.

[0031] The following describes in detail the method for integrally forming the carbon fiber structural member of the sunken mouth frame through a specific embodiment:

[0032] Reference Figures 1 to 2 As shown, the present disclosure provides a method for integrally forming a carbon fiber structural member of a sunken mouth frame, comprising:

[0033] Overall layering, folding the skin fibers multiple times, and using the folded skin fibers to layer the opening frame in layers;

[0034] The sunken frame, reinforcement area and skin layer are formed, and after the layer is laid, the product is pre-pressed in the mold and the skin is dimensional cured;

[0035] Curing and molding, the product is taken out of the oven after curing, and the outer dimensional process skin is removed;

[0036] Demolding process: using demoulding tools to remove the product from the mold;

[0037] Inspection and processing, processing product end faces and openings, etc.

[0038] The present invention folds the skin fibers multiple times, and uses the folded skin fibers to lay layers on the mouth frame in layers to ensure the continuity of the internal fibers during product preparation, thereby improving the load-bearing capacity of the structural compartment and the integrity of the product shape, and performs dimensional curing through the process skin. Using the process skin with less rigidity instead of the rigid mold can better cover the outer surface of the product during the curing process, avoiding the outer contour deviation caused by the assembly interference caused by the rigid mold.

[0039] Specifically, a molding mold is designed based on the structural characteristics of the product. The main body of the mold adopts a steel punch, which serves as an internal support. Its characteristic is that it meets the laying and rotation functions, and utilizes the movable block design to achieve the overall demoulding function of the carbon fiber structural part with a sunken mouth frame.

[0040] The structural parts made by the present disclosure are taken as an example of carbon fiber composite materials. Carbon fiber composite materials are formed by unidirectional prepreg layer laying. When laying layer design, due to the need to ensure the continuity of the overall fiber of the product, especially the continuity of the mouth frame sinking and the large area of ​​skin, the design is to fold the skin fiber, and use the folded fiber to lay the mouth frame. However, there is a difference in thickness between the skin and the sunken part of the mouth frame. If all the fibers of the skin are folded to lay the mouth frame, the mouth frame thickness will be too thick. If the extrusion of the mold physical pressure curing is performed again, a large amount of resin will be lost, thereby changing the fiber volume content, causing internal quality problems. Therefore, when considering the design safety factor and ensuring the continuity of the skin and the mouth frame junction as a whole, it is necessary to carry out local layer design, fold the skin fiber multiple times in batches, reduce the accumulation of excess fibers in the mouth frame, and ensure fiber continuity to the greatest extent. It should be noted that the internal fibers of the commonly used fiber prepreg are unidirectional fibers. When encountering the corner of the mold tooling, in order to ensure the continuity of the fibers, folding is used to allow the fibers to fit the mold surface layer.

[0041] After the layering is completed, the product needs to be pre-pressed in a rigid mold and the skin is dimensional cured, both of which are carried out using vacuum-assisted autoclave pressurization.

[0042] Our company's skin curing uses a flexible mold, which has better ductility and elasticity than a rigid mold, and the shape can be selected according to the adaptability of the product. During the process of pressing the product, the flexible mold can better fit the surface of the product, ensuring that the force is evenly distributed in all corners of the product. It can also avoid the failure of pressure conduction caused by the non-fitting between the product and the mold in some complex structures due to the excessive rigidity of the rigid mold.

[0043] After the product solidifies, it is removed from the oven, the vacuum coating material on the mold surface is removed, the outer dimensional process skin is removed, and finally, the product is completely removed from the mold using the countersunk screws and the mouth frame punch block, resulting in the carbon fiber composite cabin section. Finally, the product end faces and openings are processed.

[0044] In some embodiments, the mold pre-pressing adopts vacuum hot pressing, wherein the hot pressing temperature is set to 100° C. to 130° C., the process pressure is increased to 0.6 MPa, and the pressure increase and release rate is 20 KPa / min.

[0045] In this embodiment, the present disclosure can use a vacuum autoclave for hot pressing, and the hot pressing temperature is set to 100°C to 130°C. If it is lower than 100°C, the prepreg avant-garde and resin flow state cannot be achieved, resulting in internal bubbles and quality problems, while if it is higher than 130°C, the viscosity is too high and is not conducive to molding.

[0046] In some embodiments, before the vacuum hot pressing, mechanical pressure is applied to the sunken frame so that the fibers can better fit the mold.

[0047] In some embodiments, the temperature rise regime for the dimensional curing of the skin is 200° C. to 240° C., the whole temperature rise and fall rate is 60±5° C. / h, and the process pressure is increased to 0.6 MPa.

[0048] In this embodiment, the present disclosure sets the temperature rise system for dimensional curing of the skin to 200°C to 240°C. Within this temperature range, the resin reacts with the curing agent to produce a cross-linking reaction, thereby achieving resin curing. The curing process of the resin is a chemical reaction. Only when the temperature reaches the curing temperature do the molecules have enough energy to overcome the energy barrier of the reaction and allow the curing reaction to proceed at a considerable rate. If the temperature is lower than the curing temperature of 200°C, the molecular kinetic energy is insufficient, the reaction rate is extremely slow, and the curing phenomenon is almost undetectable. If the temperature is too high, 240°C, the curing speed will be accelerated, but there will be a temperature difference between the internal and external temperatures, thereby generating internal stress.

[0049] In some embodiments, the process has a pressurization rate of 20 kPa / min and a pressure relief rate of 10 kPa / min. The pressurization and pressure relief rates are mainly related to the properties of the resin. The pressurization rate is to allow sufficient time for the resin to expel internal bubbles before it is completely cured, and the pressure relief rate is to ensure better shape maintenance.

[0050] In some embodiments, the multiple folding of the skin fibers is divided into 0° fiber folding and 45° fiber folding. The 0° and 45° folding ensures the continuity of the fibers and the mechanical strength of the product.

[0051] In some embodiments, when the skin fibers are folded from the end frame to the skin, the folding overlap width is less than or equal to 1 mm to ensure that the fibers are continuous when folded and do not occupy unnecessary space due to excessive overlap, resulting in excessive internal stress in the product.

[0052] In some embodiments, the gap between the joints of the multiple folded skin fibers is set to 50±10 mm. Furthermore, the gap between the joints is filled with prepreg to ensure the continuity of the entire fiber.

[0053] In some embodiments, the cutting direction of the skin fiber folded ply is consistent with the fiber direction.

[0054] In the present disclosure, the terms "first", "second", and "third" are used for descriptive purposes only and are not to be understood as indicating or implying relative importance; the term "plurality" refers to two or more, unless otherwise expressly defined. Terms such as "installed", "connected", "connected", and "fixed" should be understood in a broad sense. For example, "connected" can mean a fixed connection, a detachable connection, or an integral connection; "connected" can mean a direct connection or an indirect connection through an intermediate medium. For those skilled in the art, the specific meanings of the above terms in the present disclosure can be understood according to the specific circumstances.

[0055] In the description of the present disclosure, it is to be understood that the terms "up", "down", "left", "right", "front", "back", etc., indicating directions or positional relationships, are based on the directions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present disclosure and simplifying the description, rather than indicating or implying that the device or unit referred to must have a specific direction, be constructed and operated in a specific direction, and therefore, cannot be understood as a limitation on the present disclosure.

[0056] Throughout this specification, terms such as "one embodiment," "some embodiments," and "specific embodiments" mean that the specific features, structures, materials, or characteristics described in conjunction with that embodiment or example are included in at least one embodiment or example of the present disclosure. In this specification, schematic representations of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

[0057] The above are merely preferred embodiments of the present disclosure and are not intended to limit the present disclosure. Those skilled in the art will readily appreciate that various modifications and variations of the present disclosure are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present disclosure shall be included within the scope of protection of the present disclosure.

Claims

1. A method for integrally forming a carbon fiber structural member of a sunken mouth frame, characterized in that: include: Overall layering, folding the skin fiber multiple times, and using the folded skin fiber to layer the opening frame in layers; The sunken frame, reinforcement area and skin layer are formed, and the product after layering is pre-pressed in the mold and the skin is solidified; Curing and molding, the product is taken out of the oven after curing, and the outer dimensional process skin is removed; Demolding process: using demoulding tools to remove the product from the mold; Inspection and processing, processing product end faces and openings, etc.

2. The method for integrally forming a carbon fiber structural member of a sunken mouth frame according to claim 1, characterized in that: The mold pre-pressing adopts vacuum hot pressing, wherein the hot pressing temperature is set to 100° C. to 130° C., the process is pressurized to 0.6 MPa, and the pressure increase and release rate is 20 KPa / min.

3. The method for integrally forming a carbon fiber structural member of a sunken mouth frame according to claim 2, characterized in that: Before the vacuum hot pressing, mechanical pressing is performed at the sunken opening frame.

4. The method for integrally forming a carbon fiber structural member of a sunken mouth frame according to claim 1, characterized in that: The temperature rise system of the skin dimensional curing is 200°C to 240°C, the whole temperature rise and fall rate is 60±5°C / h, and the process pressure is increased to 0.6MPa.

5. The method for integrally forming a carbon fiber structural member of a sunken mouth frame according to claim 4, characterized in that: The process pressurization rate is 20 KPa / min, and the pressure relief rate is 10 KPa / min.

6. The method for integrally forming a carbon fiber structural member of a sunken mouth frame according to claim 1, characterized in that: The multiple folding of the skin fibers is divided into 0° fiber folding and 45° fiber folding.

7. The method for integrally forming a carbon fiber structural member of a sunken mouth frame according to claim 1, characterized in that: When the skin fiber is folded from the end frame to the skin, the folded overlapping width is less than or equal to 1 mm.

8. The method for integrally forming a carbon fiber structural member of a sunken mouth frame according to claim 1, characterized in that: The gap of the joint seams of the multiple folded skin fibers is set to 50±10 mm.

9. The method for integrally forming a carbon fiber structural member of a sunken mouth frame according to claim 8, characterized in that: The gaps in the splicing seams are filled with prepreg.

10. The method for integrally forming a carbon fiber structural member of a sunken mouth frame according to claim 1, characterized in that: The cutting direction of the skin fiber folded layer is consistent with the fiber direction.

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