A method for manufacturing a high-quality integral composite skin-metal web

Abstract

The present application belongs to the technical field of composite material component manufacturing, and particularly relates to a high-quality integrated manufacturing method for a composite material skin-metal web. The present application reduces residual stress caused by the difference in thermal expansion coefficient through methods such as segmented processing of the metal web, splicing forming and surface structure design, improves the positioning accuracy of the metal web and the internal quality of the overall structure through the design application of the positioning template, and realizes high-quality and high-efficiency integrated manufacturing of the composite material skin and the metal web through process optimization, thereby laying a technical foundation for the manufacturing of composite material-metal stiffened structure components of dissimilar materials and composite processes.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of composite material component manufacturing, and particularly relates to a high-quality integrated manufacturing method for a composite material skin-metal web. BACKGROUND

[0002] With the development of composite material manufacturing technology and the increasing demand for aircraft weight reduction, carbon fiber composite material stiffened structure parts are widely used in main load-bearing structures and secondary load-bearing structures in the aviation field, such as horizontal and vertical tail wall panels, wing wall panels, hatches, and cabin doors, due to high specific strength and specific modulus of the material, strong designability of the structure, and integrative forming. Traditional carbon fiber composite material stiffened structure parts are entirely made of carbon fiber composite material, and the stiffeners and the skin are formed by co-curing, co-curing with bonding, or secondary bonding process in a heat press tank, which requires the design and manufacture of a complex positioning assembly tooling to ensure the forming quality of the structure and the positioning accuracy of the stiffeners. The positioning assembly tooling has a complex structure, high design and manufacturing cost, complicated preparation process, and low manufacturing efficiency. In addition, the positioning of the stiffeners is difficult in a high-temperature and high-pressure environment, and the position accuracy is difficult to guarantee. The complex tooling structure also increases the difficulty of vacuum bag packaging when the part is formed in a heat press tank. For example, a tooling and forming method for positioning and integrative forming of a composite material stiffened wall panel are disclosed in Chinese Patent No. CN105346102B, which can realize the integrative forming of the wall panel structure. However, the positioning tooling needs to be repeatedly installed and removed during use, and the vacuum bag needs to be opened when curing and packaging, so that the bolts pass through the positioning beam through hole outside the vacuum bag and the forming tooling inside the vacuum bag, and the bolts need to be sealed with a sealing strip at the position where they pass through the vacuum bag. There is a risk of vacuum bag leakage during curing. In addition, the parts made by co-curing with bonding and secondary bonding process need to be cured and formed in a heat press tank for multiple times, which greatly increases the manufacturing cost. Therefore, some experts have proposed a method for manufacturing a stiffened wall panel of different materials by using a hybrid process, that is, the composite material skin and the metal web are integrally formed, and then the stiffeners and the web are connected by a welding connection process, so as to finally realize the integrative manufacturing of the stiffened wall panel of different materials. At present, there is little research on the integrative forming process of the composite material skin and the metal web, and there are problems of connection quality and appearance quality caused by the mismatch of thermal expansion coefficients during the integrative forming of the two. Therefore, it is an urgent problem to realize the high-quality integrative forming of the composite material skin and the metal web. SUMMARY

[0003] Aiming at the connection quality and appearance quality problems caused by the mismatch of thermal expansion coefficient when the composite skin and metal web are integrally formed, a high-quality integrally forming method of composite skin and metal web is proposed. The pre-solidification process is adopted to control the skin stiffness and improve the appearance quality; the web is designed in a segmented form, and the size of the metal web is designed according to different curing temperatures to control the thermal expansion and reduce the residual stress of the connecting surface; a special structure is designed and manufactured on the surface of the metal web connected with the composite skin, so that the mechanical fitting of the connecting surface is realized, thereby improving the connection quality with the skin; the sample material and structure are optimized and designed to adjust the stiffness and positioning accuracy, so as to ensure the precise position of the web and the internal quality; through the process flow design, the composite skin and metal web are integrally formed with high efficiency and high quality.

[0004] The technical means adopted by the application are as follows:

[0005] A high-quality integrally manufacturing method of composite skin-metal web, the steps are as follows:

[0006] The integrally forming method of the composite skin and the metal web is characterized in that: the composite skin is pre-solidified after being laid up; the metal web is designed in a segmented form to suppress the residual stress caused by the difference of thermal expansion coefficient, and grooves or V-shaped grooves are processed on the surface to improve the interfacial bonding force between the composite skin and the metal web; a positioning sample plate with integral or split structure is designed and manufactured, which has the functions of positioning, limiting and uniform pressing to prevent the position of the metal plate from slipping during forming; the metal web and the skin are positioned and combined, the metal web is spliced in segments, and the integrally manufacturing of the composite skin and the metal web is completed by using the co-curing process.

[0007] The skin laying up is characterized in that: the skin material can be one or several of carbon fiber prepreg, glass fiber prepreg, quartz fiber prepreg or aramid fiber prepreg; after the laying up is completed, the skin is packaged into a hot press tank for pre-solidification, the pre-solidification temperature is 50-130 DEG C, the pressure is 0.3MPa-0.6MPa, and the holding time is 5-20min, so as to make it close to the real thickness after solidification, the hardness close to the composite skin after solidification, prevent the metal web from sinking too deep into the skin during the combination and solidification process, and affect the surface quality.

[0008] The metal web size is characterized in that the metal web is designed to have a thickness of 2-4 mm, a width of 20-65 mm, and a total length determined according to the skin length and design requirements. The same web can be segmented and spliced for use according to the total length and different curing temperature conditions of the composite material. The splicing position can be designed as a vertical or oblique splicing structure. According to the curing temperature range of the composite material, the web can be designed to have a length of 300-1000 mm, preventing residual stress from being generated on the bonding surface during the overall forming due to the large difference in thermal expansion coefficient between the metal web and the composite skin, and affecting the internal quality at the bonding surface.

[0009] The metal web surface structure is characterized in that a concave groove or V-shaped groove is machined on the side of the metal web bonded with the skin by machining or laser processing. The groove cavity depth is in the range of 0.1-0.5 mm, the groove cavity width is 1-5 mm, the groove cavity length is the same as the web width, and the spacing between the grooves is 5-10 mm. According to the mechanical fitting theory, the resin in the prepreg penetrates into the groove cavity of the metal web and expels the adsorbed air, thereby producing good adhesion.

[0010] The positioning template is characterized in that the positioning template can simultaneously realize positioning, limiting and uniform pressing.

[0011] 1.1 Material selection: The positioning template material can be one or a combination of two of glass fiber prepreg, carbon fiber prepreg, unvulcanized rubber and silicone rubber. The hardness can be controlled by selecting the material type and designing the layering, and the Shore D hardness is between 38 and 90.

[0012] 1.2 Structure design: The positioning template can be designed as a whole structure, with a round hole and an oblong hole designed at one end in the length direction and an oblong hole designed at the other end for positioning between the skin; the metal web of the positioning template is left with a metal web occupying space at the corresponding position, the occupying space width is 0.2-1 mm wider than the theoretical width of the metal web, and the length is 1-15 mm longer than the theoretical length of the metal web; the positioning template can also be disconnected in the middle along the length direction of the web to form a comb-shaped structure, and a round hole and an oblong hole are designed at both ends in the length direction for positioning the template on the skin surface.

[0013] 1.3 Template manufacturing: The positioning template needs to be manufactured according to the shape of the upper surface of the skin, and the fitting gap with the skin is in the range of 0-1 mm / m. When the fitting gap is greater than 1 mm / m, the fitting gap at the applied force should be no greater than 0.2 mm after applying external force.

[0014] The process flow is characterized in that a pre-solidification process is arranged to improve the appearance quality of the integrated structure; the skin and the metal web are integrally formed at one time, and only one time of entering a hot press tank is needed except for short-time pre-solidification, so that the production cost is greatly reduced; a web surface groove or V-shaped groove processing process and a surface treatment process are arranged to improve the connecting strength of the web and the skin; the web is processed in sections and spliced to form, so that the residual stress caused by the difference in the thermal expansion coefficient is reduced; and the specific process flow is as follows:

[0015] 2.1 Laying up prepreg on the surface of the skin forming tool until the specified number of layers is laid up, and then sealing and sending into a hot press tank for pre-solidification, so that the real thickness and hardness after solidification are approached;

[0016] 2.2 Fixing the positioning template on the positioning pin of the skin forming tool through the positioning holes on the positioning template, so that the positioning template is attached to the upper surface of the skin;

[0017] 2.3 Processing the metal web in sections, and processing grooves on the side of the metal web connected with the skin;

[0018] 2.4 Carrying out surface treatment on the metal web by adopting sandblasting, pickling, anodizing treatment or plasma treatment to improve the connecting strength;

[0019] 2.5 Positioning and combining the metal web with the skin at the position of the positioning template spacer, splicing the metal web in sections, and reserving 1-3 mm expansion joints between the sections to prevent residual stress from being generated at the interface of the composite skin and the metal web due to the difference in the thermal expansion coefficient during solidification;

[0020] 2.6 Fixing the metal web on the surface of the positioning template by using pressure-sensitive adhesive tape, and sealing a vacuum bag after the whole combination;

[0021] 2.7 Solidification forming: sealing and sending the combination of the skin and the metal web into a hot press tank for solidification forming, the solidification temperature is 120-230 DEG C, the solidification pressure is 0.3-0.6 MPa, the holding time is 120-240 min, and the integrated manufacturing of the composite skin and the metal web is completed.

[0022] The beneficial effects of the application are as follows:

[0023] The application provides an integrated manufacturing process method of a composite skin and a metal web, residual stress caused by the difference in the thermal expansion coefficient is reduced by means of sectional processing, splicing forming and surface structure design of the metal web, the positioning precision of the metal web and the internal quality of the integrated structure are improved by means of the design and application of the positioning template, and the integrated manufacturing of the composite skin and the metal web is realized in high quality and high efficiency by means of process optimization, thereby laying a technical foundation for the manufacturing of dissimilar material, composite process composite-metal stiffened structure parts. BRIEF DESCRIPTION OF DRAWINGS

[0024] Figure 1 A schematic diagram of the integrated structure of fiber-reinforced resin matrix composite skin and metal web;

[0025] Figure 2 This is a schematic diagram of the surface structure of a metal web.

[0026] Figure 3 This is a schematic diagram of the positioning template structure and the positioning combination of the skin and metal web.

[0027] In the diagram: 1 is the skin, 2 is the metal web, 2-1 is the vertical metal web segment structure, 2-2 is the oblique metal web segment structure, 2-3 is the integral metal web structure, 3 is the concave groove metal web surface structure, 4 is the V-groove metal web surface structure, 5 is the positioning template, 5-1 is the positioning round hole A, 5-2 is the positioning round hole B, 5-3 is the positioning oblong hole A, 5-4 is the positioning oblong hole B, and 6 is the space occupied by the metal web. Detailed Implementation

[0028] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings.

[0029] Dissimilar material reinforced wall panels manufactured using hybrid processes can replace traditional composite material reinforced wall panels. However, there is currently limited research on the integrated molding process of composite skin 1 and metal web 2, making it difficult to control the molding quality. For example... Figure 1 As shown, the fiber-reinforced resin matrix composite skin 1 and the metal web 2 are integral structures. Due to the large difference in the coefficients of thermal expansion between the fiber-reinforced resin matrix composite and the metal, there are connection quality and shape quality problems caused by the mismatch of the coefficients of thermal expansion when the two are integrally formed in the autoclave. Moreover, under high temperature and high pressure conditions, the metal web 2 is difficult to position and is easy to sink into the interior of the composite skin 1, making it difficult to guarantee product quality.

[0030] Addressing the issues of connection quality and shape quality during the integral molding of composite material skin 1 and metal web 2, this invention provides a high-quality integral molding method for composite material skin 1 and metal web 2. By employing a segmented integral molding method for the metal web 2 with skin 1 and a special surface structural design for the metal web 2, the connection quality and internal quality of the overall structure are ensured. Through pre-curing treatment of skin 1 and the design and use of positioning template 5, the shape quality and positioning accuracy of the integral molding of composite material skin 1 and metal web 2 are guaranteed, achieving high-efficiency, high-quality, and integral molding of composite material skin 1 and metal web 2. The specific implementation process is as follows:

[0031] First step, skin 1 lay-up: carbon fiber prepreg cured at 180℃, lay-up skin 1 prepreg on the surface of the tooling in order, skin 1 length 2000mm, every 3-5 layers of vacuum extraction and compaction at room temperature, after all the layers are laid up, the blank is packaged on the surface of the tooling and sent to the autoclave for pre-curing. The whole process vacuum is not less than-0.092MPa, pressurization 0.6±0.035MPa, rate 0.3MPa / min; the temperature rising rate is not more than 1.5℃ / min, rising to 90℃, 90±5℃, holding for 15min; cooling to 60℃ at a rate of not more than 1.5℃ / min, 60±5℃, holding for 2min, decompression and out of the tank.

[0032] Second step, metal web 2 preparation and surface treatment: the total length of a single web is 1800mm, considering that the thermal expansion of the web under the condition of 180℃ is about 6.2mm, therefore the metal web 2 is designed in segmented structure, which can be vertical segmented structure or oblique cut segmented structure, each segment is 300mm. Select aluminum alloy plate with 7B04 brand and 2mm thickness to process into web with width of 50mm and length of 300mm, a single web is composed of 6 segmented webs with length of 300mm; as shown in Figure 2 the recessed groove structure metal web 3 or V-shaped groove structure metal web 4 is designed and manufactured, the groove width is 2mm, the depth is 0.2mm, and the groove interval is 5mm. Use acetone solvent to clean the oil stains on the surface of the aluminum alloy web; then use a mixed solution of sodium hydroxide and sodium carbonate to perform alkaline cleaning at 50-60℃ for 0.5-1min, and rinse in tap water for 2-5min; use deoxidizing liquid to clean at room temperature for 2-5min, and rinse in tap water for 5min; put the aluminum alloy web into phosphoric acid solution, connect the direct current power supply at room temperature, and raise the direct current voltage between the electrodes from 0V to 10±1V within 2min, take out after anodizing for 20min, rinse, and dry for use.

[0033] Third step, anticorrosion isolation layer coating: coat a layer of glass fiber prepreg on the surface of the metal web 2 to prevent the composite skin 1 from directly contacting with the metal web 2 to cause electrochemical corrosion, and the resin in the layer of prepreg can also act as an adhesive. The profile of the glass fiber prepreg needs to be larger than the ground of the metal web 2 and can cover the side surface of the metal web 2.

[0034] Fourth step, positioning template 5 manufacturing and metal web 2 positioning assembly: design and manufacture split positioning template 5 with intermediate discontinuity, reserve space-occupying space at the corresponding position of the web of the positioning template 5, reserve 10mm excess in the length direction of the space-occupying space; each positioning template 5 contains two positioning holes, a round hole and an oblong hole; stick a layer of unvulcanized rubber on the surface of the positioning template 5, and then lay up 4 layers of carbon fiber tooling prepreg fabric on the surface, so that it has a certain hardness and can uniformly transmit pressure.Figure 3 As shown, the positioning template 5 is attached to the surface of the skin 11, and the metal web 2 is sequentially placed into the metal web occupying space 6 with a 1mm gap between the webs, and then fixed on the positioning template 5 with a pressure-sensitive tape.

[0035] Fifth step, curing forming: after the carbon fiber composite skin 1 and the aluminum alloy web are combined, they are packaged and sent into a hot press tank for curing forming, the curing temperature is 180±5℃, the curing pressure is 0.6±0.035MPa, and the holding time is 240min, to complete the integrated manufacturing of the composite skin 1 and the metal web 2.

Claims

1. A method of manufacturing a composite skin-metal web high quality integrated structure, characterized in that, The steps are as follows: After the composite skin (1) is laid up, pre-curing treatment is performed; The metal web (2) is designed in sections to inhibit residual stress caused by the difference in the coefficient of thermal expansion, and grooves or V-shaped grooves are processed on the surface, and the surface of the metal web (2) is treated before being connected with the skin (1) to improve the interfacial bonding force between the composite skin (1) and the metal web (2); A positioning template (5) with an integral or split structure is designed and manufactured, which has the functions of positioning, limiting and uniform pressing to prevent the position of the metal plate from slipping during forming; The metal web (2) is positioned and combined with the skin (1), the metal web (2) is spliced in sections, and the integral manufacturing of the composite skin (1) and the metal web (2) is completed by using co-curing process; The skin (1) is laid up, and after the laying up is completed, it is packaged into a hot press tank for pre-curing, the pre-curing temperature is 50-130℃, the pressure is 0.3-0.6MPa, and the holding time is 5-20min; The size design of the metal web (2) is as follows: the metal web (2) is designed to have a thickness of 2-4mm, a width of 20-65mm, and the total length of the web is determined according to the length of the skin (1) and the design requirements; the same web is designed in sections according to the total length and the curing temperature conditions of the composite material, and then spliced for use, the splicing position is designed as a vertical or oblique cutting splicing structure, the web is designed to have a length of 300-1000mm according to the different curing temperature ranges of the composite material, to prevent residual stress from being generated on the bonding surface during the integral forming due to the large difference in the coefficient of thermal expansion between the metal web (2) and the composite skin (1), which affects the internal quality at the bonding surface; The surface structure design of the metal web (2) is as follows: a concave groove or a V-shaped groove is processed on the side of the metal web (2) to be bonded with the skin (1) by mechanical processing or laser processing, the groove cavity depth is in the range of 0.1-0.5mm, the groove cavity width is 1-5mm, the groove cavity length is the same as the web width, and the spacing between the grooves is 5-10mm.

2. A method of manufacturing a composite skin-metal web high quality integrated structure according to claim 1, characterized in that, The design of the positioning template (5) is as follows: 1.1 Material selection: the material of the positioning template (5) is one or a combination of two of glass fiber prepreg, carbon fiber prepreg, unvulcanized rubber and silicone rubber, and the hardness can be controlled by selecting the material type and designing the layering, and the Shore D hardness is between 38 and 90; 1.2 Structure design: the positioning template (5) is designed as an integral structure, a round hole and a long round hole are designed at one end in the length direction, and a long round hole is designed at the other end to realize the positioning between the template and the skin (1); the metal web (2) of the positioning template (5) is designed to have a space for the metal web (2) at the corresponding position, the space width is 0.2-1mm wider than the theoretical width of the metal web (2), and the length is 1-15mm longer than the theoretical length of the metal web (2); the positioning template (5) is disconnected in the middle along the web length direction to form two matching comb structures, and a round hole and a long round hole are designed at both ends in the length direction to position the template on the surface of the skin (1). 1.3 Template manufacturing: the positioning template (5) needs to be manufactured with the upper surface profile of the skin (1), and the fitting gap of the skin (1) is in the range of 0-1mm / m. When the fitting gap is greater than 1mm / m, after applying external force, the fitting gap at the force application place should be not greater than 0.2mm.

3. A method of manufacturing a composite skin-metal web high quality monolithic according to claim 1 or 2, characterized in that, The material of the skin (1) is one or several of carbon fiber prepreg, glass fiber prepreg, quartz fiber prepreg or aramid fiber prepreg.

4. A method of manufacturing a composite skin-metal web high quality monolithic according to claim 1, characterized in that, The material of the skin (1) is one or several of carbon fiber prepreg, glass fiber prepreg, quartz fiber prepreg or aramid fiber prepreg.

5. A method of manufacturing a composite skin-metal web high quality monolithic according to claim 1 or 2 or 4, characterized in that, The process flow of the manufacturing method is as follows: 2.1 Laying up prepreg on the surface of the skin (1) forming tool until the specified number of layers is laid up, and then packaging and sending into a hot press tank for pre-curing to make it close to the real thickness and hardness after curing; 2.2 Fixing the positioning template (5) on the positioning pin of the skin (1) forming tool according to the positioning hole on the positioning template (5) to make it fit with the upper surface of the skin (1); 2.3 Processing the metal web (2) in sections, and processing grooves on the side connected with the skin (1) at the same time; 2.4 Carrying out surface treatment on the metal web (2) by sandblasting, pickling, anodizing treatment or plasma treatment to improve the connection strength; 2.5 Placing the metal web (2) at the position of the occupying strip of the positioning template (5) and positioning and combining with the skin (1), and segmentally splicing the metal web (2), reserving 1-3mm expansion joints between the segments to prevent residual stress at the interface between the composite skin (1) and the metal web (2) due to the difference in thermal expansion coefficient during curing; 2.6 Fixing the metal web (2) on the surface of the positioning template (5) with pressure-sensitive tape, and packaging the whole combination into a vacuum bag; 2.7 Curing forming: packaging the combination of the skin (1) and the metal web (2) and sending into a hot press tank for curing forming, the curing temperature is 120-230℃, the curing pressure is 0.3MPa-0.6MPa, and the holding time is 120-240min, to complete the integrated manufacturing of the composite skin (1) and the metal web (2).

6. A method of manufacturing a composite skin-metal web high quality monolithic according to claim 1, characterized in that, The process flow of the manufacturing method is as follows: 2.1 Laying up prepreg on the surface of the skin (1) forming tool until the specified number of layers is laid up, and then packaging and sending into a hot press tank for pre-curing to make it close to the real thickness and hardness after curing; 2.2 Fixing the positioning template (5) on the positioning pin of the skin (1) forming tool according to the positioning hole on the positioning template (5) to make it fit with the upper surface of the skin (1); 2.3 Processing the metal web (2) in sections, and processing grooves on the side connected with the skin (1) at the same time; 2.4 Carrying out surface treatment on the metal web (2) by sandblasting, pickling, anodizing treatment or plasma treatment to improve the connection strength; 2.5 Placing the metal web (2) at the position of the occupying strip of the positioning template (5) and positioning and combining with the skin (1), and segmentally splicing the metal web (2), reserving 1-3mm expansion joints between the segments to prevent residual stress at the interface between the composite skin (1) and the metal web (2) due to the difference in thermal expansion coefficient during curing; 2.6 Fixing the metal web (2) on the surface of the positioning template (5) with pressure-sensitive tape, and packaging the whole combination into a vacuum bag; 2.6 The metal web (2) is fixed on the surface of the positioning template (5) with pressure sensitive tape, and the whole combination is packaged in a vacuum bag; 2.7 Curing molding: the skin (1) and the metal web (2) are packaged and sent into a hot press tank for curing molding, the curing temperature is 120-230℃, the curing pressure is 0.3-0.6MPa, the holding time is 120-240min, and the integration manufacturing of the composite skin (1) and the metal web (2) is completed.

7. A method of manufacturing a composite skin-metal web high quality monolithic according to claim 3, characterized in that, The process flow of the manufacturing method is specifically as follows: 2.1 The prepreg is laid on the surface of the skin (1) forming tool until the specified number of layers is laid, and then it is packaged and sent into a hot press tank for pre-curing, so that it approaches the real thickness and hardness after curing; 2.2 The positioning template (5) is fixed on the positioning pin of the skin (1) forming tool according to the positioning holes on the positioning template (5), so that it is attached to the upper surface of the skin (1); 2.3 The metal web (2) is processed in sections, and a groove is processed on the side connected with the skin (1); 2.4 The surface of the metal web (2) is treated by sandblasting, pickling, anodizing or plasma treatment to improve the connection strength; 2.5 The metal web (2) is positioned and combined with the skin (1) at the position of the positioning template (5) occupying strip, the metal web (2) is spliced in sections, and 1-3mm expansion joints are reserved between the sections to prevent residual stress at the interface between the composite skin (1) and the metal web (2) due to the difference in thermal expansion coefficient during curing; 2.6 The metal web (2) is fixed on the surface of the positioning template (5) with pressure sensitive tape, and the whole combination is packaged in a vacuum bag; 2.7 Curing molding: the skin (1) and the metal web (2) are packaged and sent into a hot press tank for curing molding, the curing temperature is 120-230℃, the curing pressure is 0.3-0.6MPa, the holding time is 120-240min, and the integration manufacturing of the composite skin (1) and the metal web (2) is completed.

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