Vibration curing forming method for honeycomb sandwich structure

Abstract

The invention provides a vibration curing forming method for a honeycomb sandwich structure, and belongs to the technical field of composite material connection. The vibration curing forming method comprises the steps that a component of a honeycomb sandwich structure, a packaging auxiliary assembly, a vacuum bag and a mold are provided, and the component comprises an upper skin, a lower skin, a honeycomb core and two layers of adhesive films; the component and the packaging auxiliary assembly are laid on a mold and packaged through a vacuum bag, and an assembled part is obtained; and providing a fixing piece and a vibration device with an accommodating cavity, firstly fixing the assembly part on a vibration platen of the vibration device, then vacuumizing the vacuum bag, and then curing according to a preset vibration curing process to obtain the honeycomb sandwich structure. The honeycomb sandwich structure is formed based on the vibration device, and the prepared honeycomb sandwich structure has lower skin porosity and better mechanical property compared with autoclave forming by optimizing the forming process, so that the forming quality and efficiency of the honeycomb sandwich structure are improved.

Description

Technical Field

[0001] The invention belongs to the technical field of composite material connection, and in particular relates to a vibration curing molding method for a honeycomb sandwich structure. Background Art

[0002] The honeycomb sandwich structure includes a honeycomb core, and a lower skin and an upper skin disposed on both sides of the honeycomb core and connected to the honeycomb core respectively, wherein the honeycomb core is connected to the lower skin and the upper skin by adhesive film. The honeycomb sandwich structure has the advantages of light weight, high specific strength and specific stiffness, and is widely used in high-precision satellites, and primary and secondary load-bearing parts such as the leading edge, wing tip, tail, and rudder of aircraft wings.

[0003] The molding methods of honeycomb sandwich structures provided by the prior art mainly include two molding methods: co-bonding method and co-curing method. The honeycomb sandwich structure molded by the co-bonding method has good skin and internal molding quality, but the manufacturing cycle is increased, the manufacturing cost is increased, and it is difficult to accurately match the skin and the honeycomb core. The co-curing method is a method of curing the skin, the film and the honeycomb core at one time, which has the advantages of high molding efficiency and the ability to manufacture structures with complex surfaces.

[0004] At present, the co-curing molding of honeycomb sandwich structures mainly adopts autoclave molding. Based on the characteristics of autoclave molding, the honeycomb sandwich structure needs to be cured under the combined action of pressure and temperature, and the requirements for the process system are extremely strict. If the pressure in the tank is too high, it will cause the honeycomb core structure to have poor side wall compressive performance, which will cause the molded structure to have problems such as honeycomb slippage, shrinkage and skin wrinkles; if the pressure in the tank is too low, the molded honeycomb sandwich structure will have poor skin quality and bonding performance, which is manifested as a high content of pores in the skin and the glue layer. As can be seen from the above, excessive or insufficient pressure will cause the quality of the individual parts obtained by molding to be out of tolerance, resulting in the overall scrapping of the parts, resulting in high manufacturing costs and low efficiency. Summary of the invention

[0005] The purpose of the present invention is to provide a new one-time curing molding process for a honeycomb sandwich structure. The process is based on a vibration device for molding, and by optimizing the molding process, the prepared honeycomb sandwich structure has a lower skin porosity and better mechanical properties than that formed by an autoclave, thereby improving the molding quality and efficiency of the honeycomb sandwich structure.

[0006] To achieve the above object, the present invention provides a vibration curing molding method for a honeycomb sandwich structure, wherein the honeycomb sandwich structure comprises a lower skin, a honeycomb core and an upper skin stacked in a height direction, wherein the upper skin and the lower skin are connected to the honeycomb core via an adhesive film, and the vibration curing molding method comprises the following steps: Step (1), providing a component of a honeycomb sandwich structure, a packaging auxiliary component, a vacuum bag, and a mold for carrying the component of the honeycomb sandwich structure and the packaging auxiliary component, wherein the component includes an upper skin, a lower skin, a honeycomb core and two layers of adhesive film; step (2), laying the component and the packaging auxiliary component on the mold according to a preset method, and using the vacuum bag to package the component of the honeycomb sandwich structure and the packaging auxiliary component to obtain an assembled component; step (3), providing a fixing part and a vibration device with a receiving cavity, first placing the assembled component in the receiving cavity and fixing the assembled component on the vibration table of the vibration device by using the fixing part, then evacuating the vacuum bag and maintaining the vacuum degree ≤-0.098MPa, and then curing according to a preset vibration curing process, The honeycomb sandwich structure is obtained, and the preset vibration curing process includes first raising the temperature in the receiving cavity of the vibration device from room temperature to a first curing temperature, and keeping it at the first curing temperature for a first time, then raising the temperature from the first curing temperature to a second curing temperature, and keeping it at the second curing temperature for a second time, and after the second curing temperature is kept, cooling to a preset temperature to complete curing. At the same time, when the temperature in the receiving cavity of the vibration device reaches the first curing temperature, turning on the vibration function of the vibration device and applying vibration excitation in three directions, namely, X direction, Y direction and Z direction, to the vibration table according to the preset vibration acceleration, and the duration of the vibration excitation is the same as the first duration, wherein the first curing temperature is 90°C, the first duration is 30min, and the preset vibration acceleration is 10g.

[0007] In a specific embodiment, the vibration device also includes a box, a spring assembly for supporting the vibration table, and a vibration module. The vibration table is installed on the box and divides the box into the receiving cavity and the accommodating cavity. The vibration module is used to apply vibration excitation to the vibration table.

[0008] In a specific embodiment, the vibration module includes a plurality of inclined air hammers, a plurality of ventilation ducts, and an air compressor arranged in a preset arrangement. The air hammer includes a first end and a second end. The first end of the air hammer is fixedly connected to the lower surface of the vibration table. One end of each ventilation duct is connected to one of the air hammers and the other end is connected to the air compressor. The preset arrangement is that the plurality of air hammers are evenly distributed in multiple circles around the central axis of the vibration table.

[0009] In a specific embodiment, the air hammer also includes an air hammer shell having a cavity, a piston located in the cavity and capable of sliding back and forth along the length direction of the air hammer shell, a cushion block arranged on the inner wall of the air hammer shell and adjacent to the first end of the air hammer, a gas connector installed on the air hammer shell and connected to the ventilation duct, and a gas delivery pipe arranged on the piston and connected to the gas connector, the output end of the gas delivery pipe faces the second end of the air hammer, the gas compressed by the air compressor enters the cavity in sequence through the ventilation duct, the gas connector and the gas delivery pipe, driving the piston to move from the second end of the air hammer to the first end, and after the piston collides with the cushion block, the piston moves from the first end of the air hammer to the second end under the action of reaction force and gravity.

[0010] In a specific embodiment, the multiple air hammers are divided into a first air hammer, a second air hammer and a third air hammer based on the installation position, and the preset arrangement is specifically: multiple first air hammers are evenly arranged along a large square, multiple second air hammers are evenly arranged along small squares located in the large square, and a third air hammer is arranged in the center of the small square, and the center point of the large square coincides with the center point of the small square, wherein the first air hammer is a large air hammer, and the second air hammer and the third air hammer are small air hammers.

[0011] In a specific embodiment, the number of the air hammers is 13, the first ends of the eight first air hammers are located on the sides or vertices of the large square, the first ends of the four second air hammers are located at the vertices of the small square, and the first end of the third air hammer is located at the center point of the small square.

[0012] In a specific embodiment, the angle between the center axis of the first air hammer and the side where the first end of the first air hammer is located is 45 degrees, and the angle between the center axis of the second air hammer and the side where the first end of the second air hammer is located is 45 degrees.

[0013] In a specific embodiment, the second curing temperature is 130° C., and the second curing time is 2 hours.

[0014] In a specific embodiment, the packaging auxiliary components include a first isolation membrane, a second isolation membrane, a pressure equalizing plate, a breathable felt, two metal blocks and two rubber stops; the components of the honeycomb sandwich structure and the packaging auxiliary components are laid on the mold according to a preset method, specifically: first from bottom to top, lay the mold, the first isolation membrane, the lower skin, a layer of adhesive film, the honeycomb core, another layer of adhesive film, and the upper skin in sequence, and then arrange the two metal blocks at the two ends of the assembled honeycomb sandwich structure and abut against each other, and then arrange the two rubber stops on both sides of the assembled honeycomb sandwich structure and abut against each other, and finally lay the second isolation membrane, the pressure equalizing plate and the breathable felt in sequence on the upper skin.

[0015] In a specific implementation, the vibration excitation is random vibration excitation.

[0016] The beneficial effects of the present invention include at least: 1. The present invention provides a vibration curing molding method for a honeycomb sandwich structure, the vibration curing molding method comprising: step (1), providing a component of the honeycomb sandwich structure, a packaging auxiliary component, a vacuum bag, and a mold for carrying the component of the honeycomb sandwich structure and the packaging auxiliary component, wherein the component comprises an upper skin, a lower skin, a honeycomb core and two layers of adhesive film; step (2), laying the component and the packaging auxiliary component on the mold according to a preset method, and using the vacuum bag to package the component of the honeycomb sandwich structure and the packaging auxiliary component to obtain an assembled component; step (3), providing a fixing member and a vibration device having a receiving cavity, first placing the assembled component in the receiving cavity and fixing the assembled component to the vibration device using the fixing member The vibrating platen is placed on the vacuum bag, and then the vacuum bag is evacuated and the vacuum degree is maintained at ≤-0.098MPa, and then the honeycomb sandwich structure is cured according to the preset vibration curing process to obtain the honeycomb sandwich structure; the present invention adopts a vibration device for curing and molding. When the adhesive film is in a viscous flow state, the vibration device replaces the molding pressure of the autoclave by simultaneously applying vibration excitation in the X direction, the Y direction and the Z direction, so that the pores and impurities in the resin can escape in the horizontal direction (X direction and Y direction) and the vertical direction (Z direction), and at the same time promotes the resin flow and the combination of resin and fiber (upper skin / lower skin), thereby reducing the generation of defects such as pores at the junction of the molded composite skin and the skin-honeycomb core, and improving the out-of-plane compressive performance and the skin-honeycomb core bonding mechanical properties of the honeycomb sandwich structure obtained by molding.

[0017] 2. Based on the preset vibration curing process (90-30-10g), the vibration device provided by the present invention is used for curing molding, and the skin-honeycomb core peeling strength of the prepared honeycomb sandwich structure reaches 78.4N·mm / mm, and the out-of-plane compression strength reaches 2.237MPa, which are better than the peeling strength of 74.7N·mm / mm and the out-of-plane compression strength of 2.092MPa under the condition of 0.2MPa in the autoclave. By comparing the test results, it can be seen that the honeycomb sandwich structure prepared by the preset vibration curing process of the present invention has better mechanical properties and the molding quality is improved.

[0018] 3. The multiple air hammers provided by the present invention are arranged in a preset arrangement, specifically, the small steam hammers and the large steam hammers are distributed from the inside to the outside. On the one hand, it can ensure that the assembled parts placed on the vibration table are more evenly exposed to the excitation in the three directions of X, Y and Z, so that the resin flows more evenly. In this way, the porosity of the skin obtained by curing and molding is low, the chamfer shape formed in the skin-honeycomb core connection area is good, and the prepared honeycomb sandwich structure has better bonding performance and better out-of-plane compressive performance; on the other hand, it can make the vibration transmission rate in the horizontal and vertical directions higher, avoiding the distortion of vibration transmission caused by vibration excitation attenuation.

[0019] 4. The preset vibration curing process provided by the present invention (the first curing temperature is 90°C, the first time is 30 minutes, and the preset vibration acceleration is 10g) is an optimized curing process. When curing and molding are carried out in this process, the lower skin and the upper skin have lower porosity and the mechanical properties of the honeycomb sandwich structure are better, among which the better mechanical properties are specifically manifested in better bonding performance between the skin and the honeycomb core and better out-of-plane compressive performance.

[0020] In addition to the above-described purposes, features and advantages, the present invention has other purposes, features and advantages. The present invention will be further described in detail with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 A schematic diagram of a vibration device provided by an embodiment of the present invention, in which an assembly component is installed and the assembly component is in a disassembled state; Figure 2 A schematic diagram of the structure of components, packaging auxiliary components, molds, vacuum nozzles and fixing components provided in one embodiment of the present invention; Figure 3 A schematic diagram of laying out assembly components provided in one embodiment of the present invention; Figure 4 A schematic diagram of the structure of a vibration device provided by an embodiment of the present invention at one angle; Figure 5A schematic structural diagram of a vibration device provided by an embodiment of the present invention from another angle; Figure 6 for Figure 4 A cross-sectional view of the air hammer in the vibrating device shown; Figure 7 This is a process parameter diagram of the vibration curing process for preparing a honeycomb sandwich structure in Example 1; Figure 8 This is a process parameter diagram of the curing process for preparing a honeycomb sandwich structure in Comparative Example 1; Fig. 9 A comparison chart of the porosity of the lower skin and the upper skin in the honeycomb sandwich structure prepared in Examples 1 to 5 and Comparative Example 1; Fig.10 The metallographic diagram of the upper skin in the honeycomb sandwich structure prepared in Example 1, Example 3 and Comparative Example 1, wherein: Fig.10 (a) is a metallographic image of the upper skin in the honeycomb sandwich structure prepared in Comparative Example 1. Fig.10 (b) is a metallographic image of the upper skin in the honeycomb sandwich structure prepared in Example 1. Fig.10 (c) is a metallographic image of the upper skin in the honeycomb sandwich structure prepared in Example 3; Fig.11 The metallographic diagram of the lower skin of the honeycomb sandwich structure prepared in Example 1, Example 3 and Comparative Example 1, wherein: Fig.11 (a) is a metallographic image of the lower skin of the honeycomb sandwich structure prepared in Comparative Example 1. Fig.11 (b) is a metallographic image of the lower skin of the honeycomb sandwich structure prepared in Example 1. Fig.11 (c) is a metallographic image of the lower skin of the honeycomb sandwich structure prepared in Example 3; Fig.12 The load displacement curves corresponding to the peel strength test of the honeycomb sandwich structures prepared in Example 1, Example 3 and Comparative Example 1; Fig.13 It is a comparison chart of the peel strength test results of the honeycomb sandwich structures prepared in Example 1, Example 3 and Comparative Example 1; Fig.14 The load displacement curves corresponding to the compression strength test of the honeycomb sandwich structures prepared in Example 1, Example 3 and Comparative Example 1; Fig.15 It is a comparison chart of the out-of-plane compressive strength test results of the honeycomb sandwich structures prepared in Example 1, Example 3 and Comparative Example 1. DETAILED DESCRIPTION

[0022] The embodiments of the present invention are described in detail below with reference to the accompanying drawings. However, the present invention can be defined and covered by various different implementations according to the claims.

[0023] Aiming at the technical problem that when a honeycomb sandwich structure is cured and formed by an autoclave, poor quality of molded parts may be easily caused by poor pressure control in the autoclave, the present invention adopts a vibration device for curing and forming. When the adhesive film is in a viscous flow state, the vibration device replaces the molding pressure of the autoclave by simultaneously applying vibration excitation in the X direction, the Y direction and the Z direction, so that the pores and impurities in the resin can escape in the horizontal direction (X direction and Y direction) and the vertical direction (Z direction), and at the same time promotes the flow of resin and the combination of resin and fiber (upper skin / lower skin), thereby reducing the generation of defects such as pores at the junction of the molded composite skin and the skin-honeycomb core, and improving the bonding mechanical properties and out-of-plane compressive properties of the honeycomb sandwich structure obtained by molding.

[0024] See also Figures 1 to 6 The present invention provides a vibration curing molding method for a honeycomb sandwich structure, wherein the honeycomb sandwich structure comprises a lower skin, a honeycomb core and an upper skin stacked in a height direction, wherein the upper skin and the lower skin are connected to the honeycomb core via an adhesive film.

[0025] In the present invention, the vibration curing molding method is a one-time curing molding method, which comprises the following steps: Step (1), providing a component 10 of a honeycomb sandwich structure, a packaging auxiliary component 20, a vacuum bag 30, and a mold 40 for supporting the component 10 of the honeycomb sandwich structure and the packaging auxiliary component 20.

[0026] In the present invention, the components of the honeycomb sandwich structure include a lower skin 11 , an upper skin 12 , a honeycomb core 13 and two layers of adhesive films 14 .

[0027] In the present invention, the lower skin 11 and the upper skin 12 are both formed by stacking 6 to 18 layers of pre-impregnated fiber materials, and two adjacent layers of pre-impregnated fiber materials are laid in an orthogonal cross-laying manner.

[0028] In the present invention, the pre-impregnated fiber material is a carbon fiber reinforced resin-based composite material, the reinforcement is carbon fiber, and the matrix is ​​epoxy resin.

[0029] In an optional embodiment, the honeycomb core 13 is an aramid honeycomb core formed by a composite of aramid paper and phenolic resin.

[0030] In the present invention, the adhesive film 14 is a toughened epoxy resin adhesive film.

[0031] In an optional implementation, the packaging auxiliary component 20 includes a first isolation membrane 21 , a second isolation membrane 22 , a pressure equalizing plate 23 , an air-permeable felt 24 , two metal blocks 25 and two rubber blocks 26 .

[0032] In the present invention, the vacuum bag 30 is used to encapsulate the component 10 of the honeycomb sandwich structure.

[0033] In an optional embodiment, the mold 40 is a pretreated mold, wherein the pretreatment method of the mold includes: first cleaning the stains and grease on the mold with ethanol and kerosene cleaning agents respectively, and then placing it in a ventilated place for 2 to 3 minutes to dry naturally until all the moisture on the surface of the mold evaporates.

[0034] Step (2), laying the component 10 and the packaging auxiliary component 20 on the mold 40 according to a preset method, and using the vacuum bag 30 to package the component 10 of the honeycomb sandwich structure and the packaging auxiliary component 20 to obtain an assembly part 200.

[0035] It can be understood that, in the present invention, the assembly component 200 includes a mold, components sealed with a vacuum bag, and the packaging auxiliary components.

[0036] Please refer to Figure 2 and Figure 3 , the component 10 and the packaging auxiliary component 20 are laid on the mold 40 according to a preset method, specifically: first from bottom to top, lay the mold 40, the first isolation membrane 21, the lower skin 11, a layer of adhesive film 14, the honeycomb core 13, another layer of adhesive film 14, and the upper skin 12 in sequence, and then set two metal blocks 25 at both ends of the assembled honeycomb sandwich structure and abut against each other, and then set two adhesive stops 26 at both sides of the assembled honeycomb sandwich structure and abut against each other, and finally lay the second isolation membrane 22, the equalizing plate 23 and the breathable felt 24 on the upper skin 12 in sequence.

[0037] The packaging is specifically as follows: using a vacuum bag 30, the first isolation membrane 21, the lower skin 11, a layer of adhesive film 14, the honeycomb core 13, another layer of adhesive film 14, the upper skin 12, the second isolation membrane 22, the pressure equalizing plate 23, the air permeable felt 24, the metal stopper 25 and the adhesive stopper 26 are assembled together and packaged as a whole to facilitate subsequent vacuuming to form a vacuum environment.

[0038] In the present invention, the metal stopper 25 is disposed on the first isolation membrane 21 and is disposed at both ends of the assembled honeycomb sandwich structure along the length direction of the mold 40 to prevent the honeycomb sandwich structure from shifting during the curing process.

[0039] In the present invention, the height of the metal stopper 25 is the same as the height of the assembled honeycomb sandwich structure.

[0040] In the present invention, the two stoppers 26 are arranged on the first isolation membrane 21, along the width direction of the mold, and are arranged on both sides of the assembled honeycomb sandwich structure. Their functions include: 1) limiting the assembled honeycomb sandwich structure together with the metal stopper 25; 2) preventing the resin inside the skin of the honeycomb sandwich structure from flowing to the outside during the curing process.

[0041] In the present invention, the height of the rubber stopper 26 is 3-4 mm.

[0042] It is understandable that packaging using a vacuum bag also includes sealing using a sealing strip.

[0043] In the present invention, a vacuum nozzle 50 is further provided. The vacuum nozzle 50 is installed on the mold 40 and is used to communicate with a vacuum extraction device.

[0044] Step (3), providing a fixing part 60 and a vibration device 70 having a receiving cavity 70A, first placing the assembly parts in the receiving cavity and fixing the assembly parts on the vibration table 71 of the vibration device 70 using the fixing parts, then evacuating the vacuum bag and maintaining the vacuum degree ≤-0.098MPa, and then curing according to a preset vibration curing process to obtain the honeycomb sandwich structure.

[0045] The preset vibration curing process includes first raising the temperature in the receiving chamber of the vibration device from room temperature to a first curing temperature, and keeping it at the first curing temperature for a first time period, then raising the temperature from the first curing temperature to a second curing temperature, and keeping it at the second curing temperature for a second time period, and after the second curing temperature is kept, cooling to the preset temperature to complete the curing. At the same time, when the temperature in the receiving chamber of the vibration device reaches the first curing temperature, turning on the vibration function of the vibration device and applying vibration excitation to the vibration table according to the preset vibration acceleration, and the duration of the vibration excitation is the same as the first duration, wherein the first curing temperature is 90°C, the first duration is 30min, and the preset vibration acceleration is 10g.

[0046] Preferably, the second curing temperature is 130°C, the second time period is 2 hours, and the preset temperature is 60°C.

[0047] Preferably, the temperature in the receiving cavity 70A of the vibration device 70 is increased at a rate of 1-3° C. / min from room temperature to the first curing temperature, and the temperature is increased at a rate of 1-3° C. / min from the first curing temperature to the second curing temperature.

[0048] Preferably, the vibration excitation is random vibration excitation.

[0049] In an optional embodiment, the fixing member 60 includes a first metal strip 61 and a second metal strip 62, and the first metal strip 61 and the second metal strip 62 are respectively arranged at two ends of the mold 40, and the middle part of each metal strip abuts against the surface of the mold away from the vibration table and the two ends are respectively detachably connected to the vibration table.

[0050] Specifically, the first metal bead and the second metal bead are connected to the mold by bolts.

[0051] Please refer to Figure 4 and Figure 5 In an optional implementation, the vibration device 70 further includes a box 72, a spring assembly 73, a vibration module 74, and a heater.

[0052] In the present invention, the box body 72 is a square box body, specifically a rectangular box body.

[0053] In the present invention, the box body 72 includes a bottom wall 721, four side walls 722 extending from both ends and both sides of the bottom wall 721 away from the bottom wall 721, and a top wall 723 that together with the bottom wall 721 and the multiple side walls 722 form the box body 72.

[0054] In the present invention, the vibration table 71 is used to carry the assembly components, and is arranged parallel to the bottom wall / top wall of the box body 72 .

[0055] In the present invention, the vibration table 71 is installed in the middle of the box body 72, and divides the box body 72 into a receiving chamber 70A and a receiving chamber 70B which are arranged vertically.

[0056] The spring assembly 73 includes four fixing seats 731 respectively fixed to the four side walls 722 of the box body 72 , and four springs 732 , one end of which is connected to the fixing seats 731 and the other end of which is connected to the vibration table 71 .

[0057] The vibration module 74 is used to apply vibration excitation to the vibration table in the X direction, the Y direction and the Z direction simultaneously.

[0058] In an optional embodiment, the vibration module 74 includes a plurality of inclined air hammers 741 arranged in a preset arrangement, a plurality of ventilation ducts 742, and an air compressor, the air hammer 741 including a first end and a second end, the first end of the air hammer being connected to the vibration table 71, one end of each ventilation duct 742 being connected to one of the air hammers 741 and the other end being connected to the air compressor, and the preset arrangement is that the plurality of air hammers 741 are evenly distributed in multiple circles around the central axis of the vibration table 71.

[0059] In the present invention, a plurality of air hammers 741 directly act on the vibration table 71 to generate vibration impact, and the ventilation duct 72 is used to transport compressed air in the air compressor to the air hammers 741, and the air compressor is used to provide compressed air.

[0060] In the present invention, the first end of the air hammer 741 is an inclined surface, so that the connection area between the air hammer and the vibration table can be increased.

[0061] Please refer to Figure 6 In an optional embodiment, the air hammer 741 also includes an air hammer shell 7411 having a cavity, a piston 7412 located in the cavity and capable of sliding back and forth along the length direction of the air hammer shell 7411, a pad 7413 arranged on the inner wall of the air hammer shell 7411 and adjacent to the first end of the air hammer, a gas connector 7414 installed on the air hammer shell 7411 and connected to the ventilation duct 742, and a gas delivery pipe 7415 arranged on the piston 7412 and connected to the gas connector 7414, the output end of the gas delivery pipe 7415 facing the second end of the air hammer.

[0062] Preferably, the air hammer housing 7411 includes a housing body having a cavity, and a connecting portion arranged at one end of the housing body, the cross-section of the housing body is annular, and the inner diameter of the end of the housing body close to the connecting portion is smaller than the inner diameter of the end of the housing body away from the connecting portion to form a step structure; the piston 7412 includes a first piston rod close to one end of the cushion block 741 and a second piston rod connected to the first piston rod, the diameter of the first piston rod is the same as the inner diameter of the end of the housing body close to the connecting portion, and the diameter of the second piston rod is the same as the inner diameter of the end of the housing body away from the connecting portion, so that when the second piston rod abuts against the step structure, it reaches the limit position.

[0063] The gas compressed by the air compressor enters the cavity through the ventilation duct 742, the gas connecting head 7414 and the gas delivery pipe 7415 in sequence, driving the piston 7412 to move from the second end of the air hammer to the first end, and after the piston 7412 collides with the pad 7413, under the action of reaction force and gravity, the piston 7412 moves from the first end of the air hammer to the second end.

[0064] In the present invention, the gas input is adjusted in real time through a feedback system (acceleration sensor), and the gas flow and pressure are adjusted through a servo valve and a proportional valve to drive the piston to reciprocate, thereby stabilizing the vibration frequency and vibration acceleration.

[0065] In the present invention, under random vibration of a preset vibration acceleration, the frequency will continuously change within a wide band range (20-2000 Hz), and the vibration device ensures that the flow of the frequency component conforms to the PSD spectrum by dynamically adjusting the gas flow and pressure.

[0066] In a specific embodiment, the multiple air hammers are divided into a first air hammer 741A, a second air hammer 741B and a third air hammer 741C based on the installation position, and the preset arrangement is specifically: multiple first air hammers 741A are evenly arranged along a large square, multiple second air hammers 741B are evenly arranged along a small square located in the large square, and a third air hammer 741C is arranged in the center of the small square, and the center point of the large square coincides with the center point of the small square, wherein the first air hammer 741A is a large air hammer, and the second air hammer 741B and the third air hammer 741C are small air hammers.

[0067] In the present invention, a large air hammer and a small air hammer are defined based on the cross-sectional area of ​​the air hammer, and the cross-sectional area of ​​the large air hammer is larger than the cross-sectional area of ​​the small air hammer.

[0068] In a specific embodiment, the number of air hammers is 13, the first ends of the eight first air hammers 741A are located on the edges or vertices of the large square, the first ends of the four second air hammers 741B are located at the vertices of the small square, and the first end of the third air hammer 741C is located at the center point of the small square.

[0069] In the present invention, the small steam hammer and the large steam hammer are distributed from the inside to the outside. On the one hand, it can ensure that the assembled parts placed on the vibration table are more evenly stimulated in the three directions of X, Y and Z, so that the resin flows more evenly. In this way, the porosity of the skin obtained by curing and molding is low, and the chamfer shape formed in the skin-honeycomb core connection area is good. The prepared honeycomb sandwich structure has better bonding performance and better out-of-plane compressive performance; on the other hand, it can make the vibration transmission rate in the horizontal and vertical directions higher, avoiding the distortion of vibration transmission caused by vibration excitation attenuation.

[0070] Preferably, the angle between the central axis of the first air hammer and the edge where the first end of the first air hammer is located is 30~60 degrees, the angle between the central axis of the second air hammer and the edge where the first end of the second air hammer is located is 30~60 degrees, and the angle between the central axis of the third air hammer and the plane where the vibration table is located is 30~60 degrees.

[0071] More preferably, the angle between the central axis of the first air hammer 741A and the edge where the first end of the first air hammer 741A is located is 45 degrees, the angle between the central axis of the second air hammer 741B and the edge where the first end of the second air hammer 741B is located is 45 degrees, and the angle between the central axis of the third air hammer 741C and the plane where the vibration table 71 is located is 45 degrees.

[0072] In the present invention, the first air hammer 741A, the second air hammer 741B and the third air hammer 741C are inclined in the same direction.

[0073] In the present invention, the heater is an electric heater, which is used to heat the receiving cavity of the vibration device 70 .

[0074] Example 1 Preparation of honeycomb sandwich structure using the vibration curing molding method provided by the present invention Step 1.1, first clean the stains and grease on the molding mold with ethanol and kerosene cleaning agents respectively, then place the mold in a ventilated place for 2-3 minutes, wait for the moisture on the mold surface to evaporate and dry naturally, and then lay the first isolation film 21 on the molding side surface of the mold 40.

[0075] Step 1.2: Lay 7 layers of pre-impregnated fiber material on the first isolation membrane 21 in an orthogonal cross-laying manner, and lightly compact each layer of pre-impregnated fiber material by hand after laying, to complete the preparation and laying of the lower skin 11.

[0076] Step 1.3: lay a toughened epoxy resin film 14 on the lower skin 11 , place the honeycomb core (Nomex honeycomb) 13 on the film, and then lay another layer of toughened epoxy resin film 14 on the honeycomb core 13 .

[0077] Step 1.4: First, lay 7 layers of pre-impregnated fiber material (T700 / TRE231 pre-impregnated material) in an orthogonal cross-laying manner, and lightly compact by hand after each layer of pre-impregnated fiber material is laid to complete the preparation of the upper skin 12; then lay the upper skin on the film and compact it.

[0078] Step 1.5, first place a metal stopper 25 and a stopper glue 26 on the outer contour edge of the assembled honeycomb sandwich structure for limiting, then lay the second isolation membrane 22, the pressure equalizing plate 23 and the breathable felt 24 in sequence on the assembled honeycomb sandwich structure, and finally use a vacuum bag 30 to package the whole to obtain the assembled parts, and at the same time place a vacuum nozzle 50 at a suitable position on the mold 40 and open a vacuum channel.

[0079] S6. Place the assembly component 200 as a whole on the vibration table 71 of the vibration device 70, and fix it with the first metal bead 61 and the second metal bead 62; at the same time, connect the vacuum pipeline to ensure the whole process of vacuum treatment, the vacuum degree is ≤-0.098MPa, and finally cure it according to the preset vibration curing process to obtain a honeycomb sandwich structure.

[0080] See also Figure 7 The preset vibration curing process is specifically as follows: turn on the heater to heat the temperature of the receiving chamber from room temperature to the first curing temperature of 90°C at a heating rate of 2°C / min, and keep it at 90°C for a first time of 30 minutes; when the curing temperature reaches 90°C, turn on the vibration function and apply vibration excitation to the vibration table of the vibration device at a preset vibration acceleration of 10g, and set the duration of the vibration excitation to 30 minutes; after the 90°C insulation is completed, the temperature of the receiving chamber is then increased from 90°C to the second curing temperature of 130°C at a heating rate of 2°C / min, and kept for a second time of 2h, and finally the cavity temperature is reduced to 60°C by air cooling (cooling rate of 2°C / min).

[0081] Embodiment 2 to Embodiment 5 Embodiment 2 to Embodiment 5 are the same as Embodiment 1, and the only difference is that the preset vibration curing process is different. Specifically: the first curing temperature, the first duration, the second curing temperature and the second duration of Embodiment 2 and Embodiment 3 are the same as those of Embodiment 1, except that the preset vibration acceleration is different. The preset vibration acceleration of Embodiment 2 is 5g, and the preset vibration acceleration of Embodiment 3 is 15g; the first duration, the second curing temperature, the second duration and the preset vibration acceleration of Embodiment 4 are the same as those of Embodiment 1, except that the first curing temperature is different. The first curing temperature of Embodiment 4 is 80°C; the second curing temperature, the second duration and the preset vibration acceleration of Embodiment 5 are the same as those of Embodiment 1, except that the first curing temperature and the first duration are different. The first curing temperature of Embodiment 5 is 80°C and the first duration is 50min.

[0082] In order to distinguish the honeycomb sandwich structure prepared in each embodiment, the honeycomb sandwich structures of different embodiments are marked based on the first curing temperature-first duration-preset vibration acceleration corresponding to the vibration curing process, wherein the honeycomb sandwich structure prepared in Example 1 is expressed as 90-30-10g, that is, the first curing temperature is 90°C, the first duration is 30min, and the preset vibration acceleration is 10g; similarly, the honeycomb sandwich structure prepared in Example 2 is expressed as 90-30-5g, the honeycomb sandwich structure prepared in Example 3 is expressed as 90-30-15g, the honeycomb sandwich structure prepared in Example 4 is expressed as 80-30-10g, and the honeycomb sandwich structure prepared in Example 5 is expressed as 80-50-10g.

[0083] Comparative Example 1 Comparative Example 1 is the same as Example 1, the only difference being that the curing device is different. Comparative Example 1 adopts autoclave curing molding, and accordingly, the curing process is also adjusted.

[0084] Please refer to Figure 8 The curing process corresponding to Comparative Example 1 is specifically as follows: starting from room temperature, heating to 90°C at a heating rate of 2°C / min, maintaining at 90°C for 30min, and after the insulation is completed, continuing to heat from 90°C to 130°C at a heating rate of 2°C / min, maintaining at 130°C for 2h, and after the insulation is completed, the temperature gradually decreases to 60°C; the pressurization program is started at the beginning of the heating, and the pressure in the tank is increased from 0MPa to 0.2MPa, and is maintained until the temperature in the tank drops to 60°C. After the pressure maintenance is completed, the pressure in the tank is unloaded from 0.2MPa to 0MPa; a vacuum bag pressure of 0.098MPa is applied from the beginning of the experiment, maintained until the end of the pressure maintenance stage, and then unloaded to 0MPa.

[0085] The honeycomb sandwich structure prepared in Comparative Example 1 was expressed as a 0.2 MPa autoclave.

[0086] Porosity test Porosity test method: five different areas were randomly selected on the surface of the lower skin and the upper skin of the prepared honeycomb sandwich structure, and 10mm×10mm square grids were marked with a marker pen in the five areas, and then the honeycomb sandwich structure was cut with a grinding wheel cutter to obtain five groups of parallel samples with a skin surface size of 10mm×10mm; then the cross sections of the five groups of parallel samples were polished on a grinder and polisher with 800 mesh, 1000 mesh, and 1500 mesh water-abrasive sandpaper and 1000 mesh, 1200 mesh, and 1400 mesh metallographic sandpaper to ensure that there were no obvious scratches and impurities on the cross sections of the grinded samples, and then the cross sections of the samples were polished with a diamond polishing paste with a particle size of 1μm. After completing the above operations, the moisture on the surface of the samples was blown dry with a hair dryer and sealed in a vacuum box; finally, the grinded samples were placed under a metallographic microscope for observation and characterization, and the microscopic morphology of the skin cross section and the skin-core layer bonding joint was recorded, and finally Image-Pro The Plus software is used to analyze and process the recorded metallographic images of the sample cross section, and the average porosity of five groups of parallel samples is taken as the porosity of the honeycomb sandwich structure composite material product under the corresponding process conditions.

[0087] The porosity test method described above was used to test the porosity of the upper and lower skins of the honeycomb sandwich structures prepared in Examples 1 to 5 and Comparative Example 1. The test results are shown in Figure 9~Figure 11 shown.

[0088] from Fig. 9It can be seen that the upper skin and lower skin prepared in Example 1 (under 90-30-10g vibration curing conditions) have the lowest porosity, which are 0.27% and 0.39% respectively, while the upper skin and lower skin prepared in Comparative Example 1 (under 0.2MPa autoclave conditions) have porosity of 0.83% and 1.24% respectively, and the upper skin and lower skin prepared in Example 3 (under 90-30-15g vibration curing conditions) have porosity of 0.87% and 1.31% respectively.

[0089] Please refer to Fig.10 and Fig.11 ,in, Fig.10 (a) is a metallographic image of the upper skin in the honeycomb sandwich structure prepared in Comparative Example 1. Fig.10 (b) is a metallographic image of the upper skin in the honeycomb sandwich structure prepared in Example 1. Fig.10 (c) is a metallographic image of the upper skin in the honeycomb sandwich structure prepared in Example 3; Fig.11 (a) is a metallographic image of the lower skin of the honeycomb sandwich structure prepared in Comparative Example 1. Fig.11 (b) is a metallographic image of the lower skin of the honeycomb sandwich structure prepared in Example 1. Fig.11 (c) is a metallographic image of the lower skin of the honeycomb sandwich structure prepared in Example 3. Fig.10 and Fig.11 From the distribution of pore morphology, under the condition of 0.2MPa autoclave, the skin surface is concave, which will affect the shape accuracy of the honeycomb sandwich structure; and the skin section A is mainly distributed with small circular and long strip pores. Under the condition of 90-30-10g vibration curing, the surface morphology of the skin section is flat, and there are no large-sized pores or other curing defects such as delamination. Only at C are there small pores distributed in the layer. The porosity of the product is controlled to the lowest level and is below 0.5%. At the same time, the resin in the B area of ​​the skin-honeycomb core bonding is cured into a well-shaped chamfer, and the skin-honeycomb core bonding performance is excellent. Under the condition of 90-30-15g vibration curing, the product morphology is relatively flat, but there are small circular intra-layer pores and long inter-layer pores at E and F, and the resin in the D area of ​​the skin-honeycomb core bonding forms an asymmetric chamfer, which will affect the skin-honeycomb core bonding performance to a certain extent.

[0090] Based on the above analysis, it can be seen that by adopting the 90-30-10g vibration curing molding process conditions, the microscopic morphology of the honeycomb sandwich structure product obtained is good, and its porosity can be controlled below 0.5%, which is better than other process conditions.

[0091] Roller peel strength test Based on the porosity test results, the honeycomb sandwich structures prepared under 0.2 MPa autoclave conditions (Comparative Example 1), 90-30-10 g vibration curing conditions (Example 1) and 90-30-15 g vibration curing conditions (Example 3) were further subjected to roller peel strength tests.

[0092] Test method: The roller peel strength test method of the honeycomb sandwich structure is tested in accordance with the standard number GB / T 1457-2022 "Sandwich structure roller peel strength test method", and the testing machine used is the MTS universal tensile machine.

[0093] The test results are detailed in Fig.12 and Fig.13 Combined with the test results of the roller peel strength of the honeycomb sandwich structure and the metallographic analysis, it can be seen that the important factor affecting the bonding performance of the skin and the honeycomb core is the chamfer formed by the resin at the bonding point. Under the 90-30-10g vibration curing conditions, the skin-honeycomb core bonding performance reaches 78.4N·mm / mm, which is the optimal level; followed by the autoclave 0.2MPa condition, the bonding performance is 74.7N·mm / mm; when the vibration acceleration is increased to 15g, due to the increase in vibration acceleration, the resin inside the skin and the resin in the film will accelerate the flow to the honeycomb core lattice wall during the curing process, and the chamfer shape formed by the glue tumor is irregular, which affects the bonding performance of the skin-honeycomb core under this condition. At this time, the bonding performance is 71.6N·mm / mm.

[0094] Compression strength test Based on the porosity test results, out-of-plane quasi-static compressive strength tests were further performed on the honeycomb sandwich structures prepared under 0.2 MPa autoclave conditions (Comparative Example 1), 90-30-10 g vibration curing conditions (Example 1), and 90-30-15 g vibration curing conditions (Example 3).

[0095] Test method: The out-of-plane quasi-static compressive strength test method of the honeycomb sandwich structure is tested in accordance with the "Sandwich structure or core flat compression performance test method" with standard number GB / T1453-2022, where the W and L side lengths of the honeycomb sandwich structure are both 50mm, the honeycomb height is 10mm, the loading speed of the testing machine is set to 0.5mm / min, and the testing machine used is an MTS universal tensile machine.

[0096] The test results are detailed in Fig.14 and Fig.15The out-of-plane compressive strength of the honeycomb sandwich structure prepared under the vibration curing conditions of Example 1 (90-30-10g) is 2.237MPa, which is the best level; followed by Comparative Example 1 (autoclave 0.2MPa condition), the out-of-plane flat compressive strength is 2.092MPa; under the vibration curing conditions of Example 3 (90-30-15g), combined with Fig.10 and Fig.11 It can be seen that at this time, pores of different sizes are distributed in the skin layer and interlayer areas. The intralayer pores will cause defects such as resin-rich or resin-poor, while the interlayer pores will cause delamination defects in the preimpregnated fiber material. The superposition of intralayer and interlayer defects will lead to poor molding quality of the honeycomb sandwich structure skin, and its out-of-plane bearing capacity will decrease accordingly. Therefore, the out-of-plane compressive strength of the honeycomb structure under this condition is 1.858MPa, which is the lowest level under this group of conditions.

[0097] It should be noted that the resin in the present invention includes the resin of the film and the resin of the skin.

[0098] The above contents are further detailed descriptions of the present invention in combination with specific preferred embodiments, and it cannot be determined that the specific implementation of the present invention is limited to these descriptions. For ordinary technicians in the technical field to which the present invention belongs, several simple deductions and substitutions can be made without departing from the concept of the present invention, which should be regarded as belonging to the protection scope of the present invention.

Claims

1. A vibration curing molding method for a honeycomb sandwich structure, wherein the honeycomb sandwich structure comprises a lower skin, a honeycomb core and an upper skin stacked in a height direction, wherein the upper skin and the lower skin are connected to the honeycomb core via an adhesive film, characterized in that: The vibration curing molding method comprises the following steps: Step (1), providing components of a honeycomb sandwich structure, packaging auxiliary components, a vacuum bag, and a mold for carrying the components of the honeycomb sandwich structure and the packaging auxiliary components, wherein the components include an upper skin, a lower skin, a honeycomb core, and two layers of adhesive film; Step (2), laying the components and the packaging auxiliary components on the mold according to a preset method, and packaging the components of the honeycomb sandwich structure and the packaging auxiliary components with the vacuum bag to obtain an assembled part; Step (3), providing a fixing part and a vibration device having a receiving cavity, first placing the assembly component in the receiving cavity and fixing the assembly component on the vibration table of the vibration device by using the fixing part, then evacuating the vacuum bag and maintaining the vacuum degree ≤-0.098MPa, and then curing according to a preset vibration curing process to obtain the honeycomb sandwich structure, wherein the preset vibration curing process comprises first raising the temperature in the receiving cavity of the vibration device from room temperature to a first curing temperature, and keeping it at the first curing temperature for a first time, then raising the temperature from the first curing temperature to a second curing temperature, and keeping it at the second curing temperature for a second time, and after the second curing temperature is kept, cooling to a preset temperature to complete curing, and at the same time, when the temperature in the receiving cavity of the vibration device reaches the first curing temperature, turning on the vibration function of the vibration device and applying vibration excitation in three directions of X direction, Y direction and Z direction to the vibration table according to a preset vibration acceleration, and the duration of the vibration excitation is the same as the first duration, wherein the first curing temperature is 90°C, the first duration is 30min, and the preset vibration acceleration is 10g.

2. The vibration curing molding method of the honeycomb sandwich structure according to claim 1, characterized in that: The vibration device also includes a box, a spring assembly for supporting the vibration table, and a vibration module. The vibration table is installed on the box and divides the box into the receiving cavity and the accommodating cavity. The vibration module is used to apply vibration excitation to the vibration table.

3. The vibration curing molding method of the honeycomb sandwich structure according to claim 2, characterized in that: The vibration module includes a plurality of inclined air hammers, a plurality of ventilation ducts, and an air compressor arranged in a preset arrangement. The air hammer includes a first end and a second end. The first end of the air hammer is fixedly connected to the lower surface of the vibration table. One end of each ventilation duct is connected to one of the air hammers and the other end is connected to the air compressor. The preset arrangement is that the plurality of air hammers are evenly distributed in multiple circles around the central axis of the vibration table.

4. The vibration curing molding method of the honeycomb sandwich structure according to claim 3, characterized in that: The air hammer also includes an air hammer shell having a cavity, a piston located in the cavity and capable of sliding back and forth along the length direction of the air hammer shell, a cushion block arranged on the inner wall of the air hammer shell and adjacent to the first end of the air hammer, a gas connector installed on the air hammer shell and connected to the ventilation duct, and a gas delivery pipe arranged on the piston and connected to the gas connector, the output end of the gas delivery pipe faces the second end of the air hammer, the gas compressed by the air compressor enters the cavity through the ventilation duct, the gas connector and the gas delivery pipe in sequence, driving the piston to move from the second end of the air hammer to the first end, and after the piston collides with the cushion block, the piston moves from the first end of the air hammer to the second end under the action of reaction force and gravity.

5. The vibration curing molding method of a honeycomb sandwich structure according to claim 3 or 4, characterized in that: Based on the installation position, the multiple air hammers are divided into a first air hammer, a second air hammer and a third air hammer, and the preset arrangement is specifically: multiple first air hammers are evenly arranged along a large square, multiple second air hammers are evenly arranged along small squares within the large square, and a third air hammer is arranged at the center of the small square, and the center point of the large square coincides with the center point of the small square, wherein the first air hammer is a large air hammer, and the second air hammer and the third air hammer are small air hammers.

6. The vibration curing molding method of the honeycomb sandwich structure according to claim 5, characterized in that: There are 13 air hammers, the first ends of 8 first air hammers are located on the sides or vertices of the large square, the first ends of 4 second air hammers are located at the vertices of the small square, and the first end of the third air hammer is located at the center point of the small square.

7. The vibration curing molding method of a honeycomb sandwich structure according to claim 6, characterized in that: The angle between the central axis of the first air hammer and the side where the first end of the first air hammer is located is 45 degrees, and the angle between the central axis of the second air hammer and the side where the first end of the second air hammer is located is 45 degrees.

8. The vibration curing molding method for a honeycomb sandwich structure according to any one of claims 1 to 4, characterized in that: The second curing temperature is 130° C., and the second curing time is 2 hours.

9. The vibration curing molding method for a honeycomb sandwich structure according to any one of claims 1 to 4, characterized in that: The packaging auxiliary assembly includes a first isolation film, a second isolation film, a pressure equalizing plate, a breathable felt, two metal blocks and two rubber blocks; The components of the honeycomb sandwich structure and the packaging auxiliary components are laid on the mold according to a preset method, specifically: first from bottom to top, lay the mold, the first isolation membrane, the lower skin, a layer of adhesive film, the honeycomb core, another layer of adhesive film, and the upper skin in sequence, and then set two metal blocks at the two ends of the assembled honeycomb sandwich structure respectively and abut against each other, and then set two adhesive stops respectively on both sides of the assembled honeycomb sandwich structure and abut against each other, and finally lay the second isolation membrane, the equalizing plate and the breathable felt in sequence on the upper skin.

10. The vibration curing molding method of a honeycomb sandwich structure according to claim 1, characterized in that: The vibration excitation is random vibration excitation.

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