Foamed rubber cushion pad for low-altitude aircraft and preparation method of foamed rubber cushion pad
The foamed rubber buffer pad designed with gradient density structure and co-vulcanization process solves the problems of collapse after long-term compression and easy damage under repeated impact of existing buffer pad materials, and achieves high reliability and long service life buffer performance, which is suitable for frequent take-off and landing and complex environment of low-altitude aircraft.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-11-03
- Publication Date
- 2026-03-31
AI Technical Summary
Existing cushioning materials cannot recover their original thickness after prolonged or repeated compression, resulting in permanent collapse and reduced cushioning performance. Furthermore, the rubber molecular chains and foam pore wall structure are easily damaged and broken under repeated impacts and vibrations, failing to meet the high reliability and long lifespan requirements of low-altitude aircraft with frequent take-offs and landings and complex operating environments.
The foamed rubber cushioning pad, designed with a gradient density structure, includes a high-density impact layer, a medium-to-high density transition layer, a low-density high-resilience cushioning layer, and a medium-density support layer. It forms an integrated structure through a co-vulcanization process, and macroscopic cavities are designed to penetrate between each layer. Using EPDM rubber or silicone rubber as the matrix, and with the addition of reinforcing agents and cell stabilizers, it achieves energy dissipation and efficient absorption in stages.
It significantly improves the resistance to permanent compressive deformation, ensuring that the material quickly returns to its original shape after instantaneous impact, enhancing the material's mechanical strength and resilience, avoiding material aging and cracking, maintaining structural integrity and performance stability, and meeting the high reliability and long service life requirements of low-altitude aircraft.
Smart Images
Figure CN121756683A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of aircraft cushioning technology, specifically to a foamed rubber low-altitude aircraft cushioning pad and its preparation method. Background Technology
[0002] With the rapid development of the low-altitude economy, applications such as drone logistics, agricultural plant protection, and urban air transportation are becoming increasingly widespread. These low-altitude aircraft are characterized by frequent takeoffs and landings and complex operating environments, thus placing stringent requirements on their landing gear cushioning systems, demanding lightweight design, high reliability, long lifespan, and strong environmental adaptability.
[0003] Currently, existing technologies include cushioning pads made from polyurethane foam, ethylene-vinyl acetate copolymer foam, or ordinary rubber foam. However, these existing technologies still have many problems that need to be solved in practical applications: after being compressed for a long time or repeatedly, the material cannot return to its original thickness, resulting in permanent collapse. For cushioning pads, this directly leads to a decrease in cushioning performance and loss of protective function. Under repeated impacts, vibrations, and deformations, the rubber molecular chains and foam pore wall structure will gradually be damaged and broken, causing the material to harden, lose elasticity, or crack. Therefore, we propose a foamed rubber low-altitude aircraft cushioning pad and its preparation method to solve the above-mentioned problems. Summary of the Invention
[0004] To address the shortcomings of existing technologies, this invention provides a foamed rubber buffer pad for low-altitude aircraft and its preparation method. It solves two major drawbacks of existing buffer pads made from polyurethane foam, ethylene-vinyl acetate copolymer foam, or ordinary rubber foam materials: first, the material cannot recover its original thickness after prolonged or repeated compression, easily leading to permanent collapse, which in turn reduces buffering performance and reduces its protective function for low-altitude aircraft; second, under repeated impacts, vibrations, and deformations, the rubber molecular chains and foam pore wall structure are easily damaged and broken, causing the material to harden, lose elasticity, or even rupture, failing to meet the high reliability and long lifespan requirements of buffer systems in scenarios with frequent takeoffs and landings and complex operating environments for low-altitude aircraft.
[0005] To achieve the above objectives, the present invention provides the following technical solution: a foamed rubber low-altitude aircraft buffer pad, comprising a buffer pad body;
[0006] The cushioning pad body has a gradient density structure design, and the cushioning pad body includes a functional layer integrally bonded from top to bottom through a co-vulcanization process, the functional layer including:
[0007] The impact layer is a high-density foamed rubber layer;
[0008] The transition layer is a medium- to high-density foamed rubber layer;
[0009] The buffer layer is a low-density, high-resilience foamed rubber layer.
[0010] The support layer is a medium-density, high-toughness foamed rubber layer.
[0011] The impact layer, transition layer, buffer layer and support layer are made of foamed rubber material, which is based on EPDM rubber or silicone rubber and contains reinforcing agent, foaming agent, peroxide vulcanizing agent and cell stabilizer.
[0012] The cell stabilizer is a thermoplastic elastomer or a low-melting-point polymer powder.
[0013] Preferably, the reinforcing agent is silica, or a mixture of silica and carbon black.
[0014] Preferably, the foaming agent is azodicarbonamide.
[0015] Preferably, the density of the impact layer is 40%-60% higher than that of the buffer layer, the density of the support layer is 20%-30% higher than that of the buffer layer, and the density of the transition layer is 15%-35% higher than that of the buffer layer.
[0016] Preferably, it also includes macroscopic cavities, which are regularly arranged through holes that penetrate the entire thickness of the cushioning pad body, i.e., they pass through the impact layer, transition layer, buffer layer and support layer at the same time.
[0017] This invention provides a method for preparing a foamed rubber low-altitude aircraft buffer pad, which includes the following steps:
[0018] S1. Prepare four sets of foamed rubber compounds corresponding to the functional layers, impact layer, transition layer, buffer layer and support layer respectively; the raw materials of the foamed rubber compounds all contain EPDM or silicone rubber matrix, reinforcing agent, foaming agent, peroxide vulcanizing agent and cell stabilizer.
[0019] S2. The four groups of compound rubbers prepared in S are calendered or extruded to produce unvulcanized rubber sheets of the corresponding sizes.
[0020] S3. Following the order of impact layer, transition layer, buffer layer, and support layer, stack the four layers of uncured film from top to bottom.
[0021] S4. Place the stacked film assembly into a preheated mold for molding and vulcanization. During the vulcanization process, the foaming agent decomposes, and each layer of film foams simultaneously and is combined into one through co-vulcanization to form a buffer pad body with a gradient density structure.
[0022] S5. After vulcanization is complete, remove the product from the mold and allow it to cool.
[0023] Preferably, in step S1, the cell stabilizer is a thermoplastic polyurethane elastomer, polyamide micropowder, or polyethylene wax micropowder.
[0024] Preferably, in step S1, the type and amount of foaming agent are adjusted to control the impact layer, transition layer, buffer layer, and support layer of each functional layer to reach their corresponding preset density.
[0025] Preferably, in step S4, the mold is provided with a corresponding mold core, so that during the molding co-vulcanization foaming process, a macroscopic cavity that runs through the entire thickness of the buffer pad body and is arranged in a regular pattern can be directly integrally formed.
[0026] Preferably, in step S4, the vulcanization temperature is controlled above the decomposition temperature of the foaming agent and below the decomposition temperature of the rubber matrix, the vulcanization pressure is 5-20 MPa, and the vulcanization time is determined according to the thickness of the rubber compound and is 10-60 minutes.
[0027] Beneficial effects
[0028] This invention provides a foamed rubber buffer pad for low-altitude aircraft and its preparation method. Compared with the prior art, it has the following advantages:
[0029] This foamed rubber low-altitude aircraft buffer pad and its preparation method utilize a gradient density structure consisting of a high-density impact layer, a medium-high density transition layer, a low-density high-resilience buffer layer, and a medium-density support layer. The synergistic macroscopic cavity design throughout each layer enables the gradual dissipation and efficient absorption of impact energy. The low-density, high-resilience characteristics of the buffer layer ensure that the material can quickly recover its original shape after being subjected to instantaneous impact, significantly improving its resistance to permanent compression deformation and effectively preventing buffer performance degradation due to permanent collapse. Secondly, by using EPDM rubber or silicone rubber as the matrix, and combining it with specific reinforcing agents and cell stabilizers, a co-vulcanization process is used to form an integrated stable cell structure and a robust interlayer interface. This greatly enhances the material's mechanical strength, resilience, and dynamic fatigue resistance, allowing it to maintain structural integrity and stable performance even under repeated impacts and vibrations. This fundamentally overcomes the problems of material aging, hardening, or cracking in existing technologies. Attached Figure Description
[0030] Figure 1 This is a cross-sectional view of the main body structure of the buffer pad of the present invention;
[0031] Figure 2 This is a flowchart illustrating the preparation method of a foamed rubber buffer pad for low-altitude aircraft according to the present invention.
[0032] In the diagram: 1. Buffer pad body; 101. Impact layer; 102. Transition layer; 103. Buffer layer; 104. Support layer. Detailed Implementation
[0033] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.
[0034] like Figure 1 As shown:
[0035] A foamed rubber low-altitude aircraft buffer pad, comprising a buffer pad body 1;
[0036] The cushioning pad body 1 has a gradient density structure design. The cushioning pad body 1 includes a functional layer integrally bonded together from top to bottom through a co-vulcanization process. The functional layer includes:
[0037] Impact layer 101 is a high-density foamed rubber layer;
[0038] Transition layer 102 is a medium-to-high density foamed rubber layer;
[0039] Buffer layer 103 is a low-density, high-resilience foamed rubber layer;
[0040] Support layer 104 is a medium-density, high-toughness foamed rubber layer;
[0041] Among them, the impact layer 101, the transition layer 102, the buffer layer 103 and the support layer 104 are made of foamed rubber material, which is based on EPDM rubber or silicone rubber and contains reinforcing agent, foaming agent, peroxide vulcanizing agent and cell stabilizer.
[0042] The cell stabilizer is a thermoplastic elastomer or a low-melting-point polymer powder;
[0043] The reinforcing agent is silica, or a mixture of silica and carbon black, and the foaming agent is azodicarbonamide;
[0044] The density of the impact layer 101 is 40%-60% higher than that of the buffer layer 103, the density of the support layer 104 is 20%-30% higher than that of the buffer layer 103, and the density of the transition layer 102 is 15%-35% higher than that of the buffer layer 103.
[0045] It also includes macroscopic cavities, which are regularly arranged macroscopic cavities that are through holes that penetrate the entire thickness of the buffer pad body 1, that is, they pass through the impact layer 101, the transition layer 102, the buffer layer 103 and the support layer 104 at the same time.
[0046] In this implementation scheme: When the aircraft lands and contacts the ground, the instantaneous impact load of the foamed rubber low-altitude aircraft buffer pad is first applied to the uppermost impact layer 101 of the buffer pad. The impact layer is a high-density foamed rubber layer, and its dense pore structure can quickly disperse the concentrated impact load, converting "point impact" into "area pressure", while preventing sharp foreign objects on the ground such as stones and branches from piercing the buffer pad and protecting the underlying structure from damage.
[0047] The pressure dispersed by the impact layer is transmitted to the transition layer 102. The medium-to-high density structure of the transition layer 102 plays an energy transition role. Since the density of the transition layer 102 is between that of the impact layer 101 and the buffer layer 103, it can avoid stress concentration caused by direct contact between two materials of different densities, and smoothly transmit the pressure to the buffer layer 103, preventing the pores of the buffer layer 103 from rupturing due to excessive local pressure.
[0048] After the pressure is transmitted to the buffer layer 103, the low-density, high-resilience pore structure of the buffer layer 103 begins to play a core role. The pores are compressed under pressure, and most of the impact energy is absorbed through the deformation of the pore walls during the process. At the same time, because the buffer layer 103 uses a high-resilience rubber matrix and a stable cross-linked structure, the pores can rebound quickly after compression, avoiding permanent deformation and ensuring that good buffering performance can still be maintained during the next take-off and landing.
[0049] The remaining energy not absorbed by the buffer layer is transferred to the support layer 104. The medium-density, high-toughness structure of the support layer 104 provides stable support, further transferring and dispersing the energy to the aircraft landing gear, preventing excessive local stress on the landing gear. At the same time, the high toughness of the support layer can resist fatigue damage caused by repeated deformation, extending the overall service life of the buffer pad.
[0050] The macroscopic cavity that runs through each layer can provide "deformation avoidance space" during the buffering process. When the buffer pad is compressed, the volume of the macroscopic cavity will change with the deformation of the material, reducing the pressure inside the buffer pad body 1 and avoiding structural damage to the material due to excessive pressure.
[0051] like Figure 2 As shown:
[0052] This invention provides a method for preparing a foamed rubber low-altitude aircraft buffer pad, the method comprising the following steps:
[0053] S1. Prepare four sets of foamed rubber compounds corresponding to the impact layer 101, transition layer 102, buffer layer 103, and support layer 104, respectively. The raw materials of each compound include 100 parts by weight of EPDM rubber or silicone rubber matrix, 30-50 parts by weight of reinforcing agent, 5-15 parts by weight of foaming agent, 1-3 parts by weight of peroxide vulcanizing agent, and 2-5 parts by weight of cell stabilizer. The density of each layer is controlled by adjusting the amount of foaming agent: 5-8 parts by weight of foaming agent for impact layer 101, 8-10 parts by weight for transition layer 102, 12-15 parts by weight for buffer layer 103, and 10-12 parts by weight for support layer 104. At the same time, the cell stabilizer is selected according to the type of matrix rubber. Thermoplastic polyurethane elastomer is preferred for EPDM rubber matrix, and polyamide micro powder is preferred for silicone rubber matrix.
[0054] S2. The four groups of compound rubbers prepared in S1 are calendered by a calender at a calendering temperature of 50-80℃ and a calendering speed of 1-2m / min, or extruded by an extruder at a temperature of 80-100℃ and an extrusion pressure of 5-10MPa to produce uncured rubber sheets with a thickness that meets the design requirements. The thickness of the impact layer is 2-5mm, the transition layer is 3-6mm, the buffer layer is 5-10mm, and the support layer is 3-5mm.
[0055] S3. Following the order of impact layer 101, transition layer 102, buffer layer 103, and support layer 104, stack the four uncured film layers from top to bottom. During the stacking process, ensure that the edges of each layer are aligned to avoid misalignment. At the same time, apply a small amount of curing accelerator, such as zinc oxide, to the contact surface of the film to improve the co-curing effect.
[0056] S4. Place the stacked film assembly into a preheated mold (preheated to 160-180℃) for compression molding and vulcanization. The mold contains a core corresponding to the macroscopic cavity, with the core diameter matching the cavity aperture. The vulcanization pressure is controlled at 5-20MPa, adjusted according to the thickness of the cushioning pad; the greater the thickness, the higher the pressure. The vulcanization temperature is controlled above the foaming agent decomposition temperature of 160-200℃ and below the rubber matrix decomposition temperature of approximately 250℃ for EPDM rubber and approximately 300℃ for silicone rubber. Specifically, the temperature is 170-190℃. During the vulcanization process, the foaming agent decomposes to produce gas, and each layer of rubber simultaneously foams to form a cell structure. Through co-vulcanization, the rubber molecular chains of each layer cross-link and become integrated. At the same time, the mold core directly forms the macroscopic cavity, ultimately forming a buffer pad body 1 with a gradient density structure and macroscopic cavity. The vulcanization time is determined according to the total thickness of the rubber compound. For every 1mm increase in thickness, the vulcanization time increases by 3-5 minutes, and the total vulcanization time is controlled to be 10-60 minutes.
[0057] S5. After vulcanization is complete, cool the mold to below 80°C, then open the mold and remove the product. Place the product in a cooling rack to cool naturally to room temperature for 2-4 hours, or accelerate cooling by air cooling for 30-60 minutes to avoid deformation of the product due to uneven cooling at high temperature.
[0058] This solution utilizes a gradient density structure consisting of a high-density impact layer, a medium-to-high density transition layer, a low-density high-resilience buffer layer, and a medium-density support layer. This, combined with a macroscopic cavity design that runs through each layer, achieves progressive dissipation and efficient absorption of impact energy. The low-density, high-resilience characteristics of the buffer layer ensure that the material quickly recovers its original shape after being subjected to instantaneous impact, significantly improving its resistance to permanent compression deformation and effectively preventing buffer performance degradation due to permanent collapse. Secondly, by using EPDM rubber or silicone rubber as the matrix, and combining it with specific reinforcing agents and cell stabilizers, a co-vulcanization process is used to form an integrated, stable cell structure and a robust interlayer interface. This greatly enhances the material's mechanical strength, resilience, and resistance to dynamic fatigue, allowing it to maintain structural integrity and stable performance even under repeated impacts and vibrations. This fundamentally overcomes the problems of material aging, hardening, or cracking in existing technologies.
[0059] It should be noted that the cushioning pad is prepared based on EPDM rubber:
[0060] Impact layer 101 compound: 100 parts by weight of EPDM rubber, 40 parts by weight of silica, 6 parts by weight of azodicarbonamide, 2 parts by weight of dicumyl peroxide, and 3 parts by weight of thermoplastic polyurethane elastomer, mixed in an internal mixer at 110-120℃ for 10-15 minutes.
[0061] Transition layer compound 102: 100 parts by weight of EPDM rubber, 35 parts by weight of silica, silica:carbon black = 2:1, 9 parts by weight of azodicarbonamide, 2 parts by weight of dicumyl peroxide, and 2 parts by weight of thermoplastic polyurethane elastomer, are mixed in an internal mixer at 100-110℃ for 10 minutes.
[0062] Buffer layer 103 compound: 100 parts by weight of EPDM rubber, 30 parts by weight of silica, 14 parts by weight of azodicarbonamide, 1.5 parts by weight of dicumyl peroxide, and 4 parts by weight of thermoplastic polyurethane elastomer, mixed in an internal mixer at 90-100℃ for 8-10 minutes.
[0063] Support layer 104 compound: 100 parts by weight of EPDM rubber, 38 parts by weight of silica, silica:carbon black = 3:1, 11 parts by weight of azodicarbonamide, 2 parts by weight of dicumyl peroxide, and 3 parts by weight of thermoplastic polyurethane elastomer, mixed in an internal mixer at 100-110℃ for 10 minutes.
[0064] Preparation of buffer pads based on silicone rubber:
[0065] Impact layer 101 compound: 100 parts by weight of silicone rubber, 45 parts by weight of silica, 7 parts by weight of azodicarbonamide, 2.5 parts by weight of benzoyl peroxide, and 3 parts by weight of polyamide powder are mixed in an internal mixer at 90-100°C for 12 minutes.
[0066] Transition layer 102 compound: 100 parts by weight of silicone rubber, 40 parts by weight of silica, 10 parts by weight of azodicarbonamide, 2.5 parts by weight of benzoyl peroxide, and 2.5 parts by weight of polyamide powder are mixed in an internal mixer at 85-95°C for 10 minutes.
[0067] Buffer layer 103 compound: 100 parts by weight of silicone rubber, 35 parts by weight of silica, 15 parts by weight of azodicarbonamide, 2 parts by weight of benzoyl peroxide, and 4.5 parts by weight of polyamide powder are mixed in an internal mixer at 80-90°C for 9 minutes.
[0068] Support layer 104 compound: 100 parts by weight of silicone rubber, 42 parts by weight of silica, 12 parts by weight of azodicarbonamide, 2.5 parts by weight of benzoyl peroxide, and 3.5 parts by weight of polyamide powder are mixed in an internal mixer at 85-95°C for 10 minutes.
[0069] Finally, it should be noted that the above descriptions are merely preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.
Claims
1. A foamed-rubber low-altitude aircraft cushion, characterized by: The cushioning pad body (1) is designed in a gradient density structure, and comprises functional layers which are integrally compounded by co-vulcanization from top to bottom. The impact layer (101) is a high-density foamed rubber layer. The excessive layer (102) is a medium-high-density foamed rubber layer. The cushioning layer (103) is a low-density high-rebound foamed rubber layer. The support layer (104) is a medium-density high-toughness foamed rubber layer. The impact layer (101), the excessive layer (102), the cushioning layer (103) and the support layer (104) are made of foamed rubber material, and the foamed rubber material takes ethylene-propylene-diene rubber or silicone rubber as a base body and contains reinforcing agent, foaming agent, peroxide vulcanizing agent and cell stabilizer. The cell stabilizer is thermoplastic elastomer or low-melting-point polymer micro powder. The reinforcing agent is white carbon black or a mixture of white carbon black and carbon black.
2. The foamed-rubber low-altitude aircraft cushion of claim 1, wherein: The foaming agent is azodicarbonamide.
3. The foamed-rubber low-altitude aircraft cushion of claim 2, wherein: The density of the impact layer (101) is 40%-60% higher than that of the cushioning layer (103), the density of the support layer (104) is 20%-30% higher than that of the cushioning layer (103), and the density of the excessive layer (102) is 15%-35% higher than that of the cushioning layer (103).
4. The foamed-rubber low-altitude aircraft cushion of claim 2, wherein: It also comprises macro cavities which are through holes penetrating through the entire thickness of the cushioning pad body (1), i.e. simultaneously penetrating through the impact layer (101), the excessive layer (102), the cushioning layer (103) and the support layer (104).
5. The foamed-rubber low-altitude aircraft cushion of claim 1, wherein: It comprises the following steps:
6. A process for the production of a foamed-rubber low-altitude aircraft cushion for the production of a foamed-rubber low-altitude aircraft cushion according to any one of claims 1 to 5, characterized in that: S1, four groups of foamed rubber mixing gums corresponding to the functional layers of the impact layer (101), the excessive layer (102), the cushioning layer (103) and the support layer (104) are respectively prepared; the raw materials of the foamed rubber mixing gums all contain ethylene-propylene-diene rubber or silicone rubber base body, reinforcing agent, foaming agent, peroxide vulcanizing agent and cell stabilizer; S2, the four groups of mixing gums prepared in S1 are respectively calendered or extruded to prepare unvulcanized rubber sheets of corresponding sizes; S3, four unvulcanized rubber sheets are laminated from top to bottom in the order of the impact layer (101), the excessive layer (102), the cushioning layer (103) and the support layer (104); S4, the laminated rubber sheet group is placed in a preheated mold for mold vulcanization; in the vulcanization process, the foaming agent decomposes, and each layer of rubber sheet is foamed and integrally compounded by co-vulcanization to form a cushioning pad body (1) with a gradient density structure; S5, after the vulcanization is completed, the product is taken out of the mold and cooled. In S1, the cell stabilizer is thermoplastic polyurethane elastomer, polyamide micro powder or polyethylene wax micro powder.
7. The method of claim 6, wherein: In S1, the types and amounts of foaming agents are adjusted to control the corresponding preset densities of the impact layer (101), the excessive layer (102), the cushioning layer (103) and the support layer (104).
8. The method of claim 6, wherein: In S4, the mold is provided with corresponding mold cores, so that the macro cavities which are through holes penetrating through the entire thickness of the cushioning pad body (1) are directly integrally formed in the mold co-vulcanization foaming process.
9. The method of claim 6, wherein: 10. The method of claim 6, wherein: In the S4, the vulcanization temperature is controlled to be above the decomposition temperature of the foaming agent and below the decomposition temperature of the rubber matrix, the vulcanization pressure is 5-20 MPa, and the vulcanization time is determined as 10-60 minutes according to the thickness of the rubber compound.