Multi-layer memory wave spring and preparation method

Abstract

The invention discloses a multi-layer memory wave spring and a preparation method, and the multi-layer memory spring comprises a first wave spring which is a single-layer annular closed type memory alloy wave spring and is located on the two end faces of the whole multi-layer memory wave spring; the second wave spring is a single-layer annular closed type wave spring made of memory alloy and is positioned between the two end surfaces; the first wave spring is in a martensite state at the service temperature of the multi-layer memory wave spring, and the second wave spring is in an austenite state at the service temperature of the multi-layer memory wave spring. The problems that an existing wave spring sealing gasket is poor in sealing performance in the using process and the elasticity is attenuated in the long-time using process can be effectively solved.

Description

Technical Field

[0001] The present application relates to a spring, in particular to a multi-layer memory wave spring and a preparation method thereof. Background Art

[0002] Aviation sealing technology plays a key role in a variety of critical applications, including aircraft and engine accessory transmission systems, engine primary and secondary airflow paths, main shaft bearing lubricating oil systems, and helicopter transmission systems. It is primarily used to seal fluids such as air, fuel, and lubricating oil. A sealing assembly typically consists of a pair of sliding sealing surfaces, known as a primary seal pair. When the sealing medium pressure acts on the primary seal pair, this pressure can cause the sealing surfaces to separate. To ensure close contact between the primary seal pairs, compensating components such as elastic elements must provide compensating force.

[0003] With the increasing demand for sealing technology in military and civilian aircraft engines, wave springs have found widespread application in aerospace applications due to their compact structure, strong vibration absorption and rebound capabilities, and excellent high-temperature and corrosion resistance. Wave springs, formed by circularly bending multiple peaks and troughs to form a thin, annular structure, can deform under axial load and return to their original shape after the load is removed. They are widely used in applications requiring high performance, such as cushioning, compensation, and shock absorption.

[0004] However, wave springs made of traditional metal materials have certain limitations: First, ordinary metal wave springs are prone to plastic deformation during long-term use, resulting in a decrease in elastic performance. To address these technical difficulties, shape memory alloys, as a material with superelasticity, high strength, high toughness, and corrosion resistance, have become a new material for wave springs, with the potential to maintain excellent performance in extreme environments. Among them, the anti-scalding straw disclosed in patent CN221356499U uses a single-layer homogeneous shape memory alloy wave spring as an actuator. When the water temperature exceeds the austenite phase transition temperature of the shape memory alloy, it acts to close the water pipe. However, the above-mentioned shape memory alloy wave spring is a single-layer wave spring and mainly serves as an actuator, not a seal.

[0005] Patent US9039766B1 mentions the use of shape memory alloys to make multi-layer wave springs for use in spinal implants to absorb energy and provide cushioning. To prepare multi-layer wave springs, the patent mentions bending shape memory alloy wire or strip into a designed wave structure through mechanical processing methods (such as winding or molding), maintaining a stable shape with a fixture or mold, and then undergoing subsequent heat treatment to achieve shaping. However, this shape memory alloy wave spring has a single mechanical property and an open structure, which is not suitable for high-pressure sealing applications.

[0006] Since aviation sealing technology needs to face high pressure and a wide temperature range (-50 to 300°C), the shape memory alloy wave springs mentioned in the above patents cannot meet the more stringent aviation sealing environment requirements and are therefore difficult to directly apply to this field. Summary of the Invention

[0007] The embodiments of the present application provide a multi-layer memory wave spring and a preparation method thereof, which are used to solve the technical problem that existing memory wave springs are not well applicable to the field of aviation sealing.

[0008] In a first aspect of the present application, a multi-layer memory wave spring is provided, comprising:

[0009] The first wave spring is a single-layer annular closed-end memory alloy wave spring located at both end surfaces of the entire multi-layer memory wave spring;

[0010] The second wave spring is a single-layer annular closed-end memory alloy wave spring, located between the two end surfaces;

[0011] The first wave spring is in a martensite state at a service temperature of the multi-layer memory wave spring, and the second wave spring is in an austenite state at a service temperature of the multi-layer memory wave spring.

[0012] Furthermore, the martensitic transformation starting temperature M of the first wave spring is s Higher than the service temperature of the multi-layer memory wave spring, the austenite phase transformation end temperature of the second wave spring is A f Lower than the service temperature of multi-layer memory wave spring.

[0013] Furthermore, at least one end side has a first multi-layer structure formed by stacking a plurality of first wave springs.

[0014] Furthermore, a second multi-layer structure formed by stacking a plurality of second wave springs is provided between the two end sides.

[0015] Furthermore, a third multi-layer structure formed by stacking a plurality of first wave springs and second wave springs is provided between the two end sides, and the first wave springs in the third multi-layer structure are at least located between every two second wave springs.

[0016] Furthermore, the phase transition temperatures of all the first wave springs are the same, or the phase transition temperatures of the first wave springs gradually decrease along the central axis of the multi-layer memory wave spring from the end surface toward the center thereof.

[0017] Furthermore, the phase transition temperatures of all the second wave springs are the same, or the phase transition temperatures of the second wave springs gradually decrease along the central axis of the multi-layer memory wave spring from the end surface toward the center thereof.

[0018] A second aspect of the present application provides a method for preparing a multi-layer memory wave spring, comprising:

[0019] Prepare a single-layer annular closed first wave spring;

[0020] Prepare a single-layer annular closed second wave spring;

[0021] The first wave springs are arranged at both ends and the second wave spring is arranged between the two ends, and the layers are metallurgically bonded;

[0022] Wherein, the first wave spring is in a martensite state at the service temperature of the multi-layer memory wave spring, and the second wave spring is in an austenite state at the service temperature of the multi-layer memory wave spring.

[0023] Furthermore, the interlayer metallurgy is carried out under the following conditions: temperature 700-1100° C., vacuum degree ≤5×10-3 Pa, holding time 2-3 hours, and forming an interdiffusion layer with a thickness of 2-5 μm after welding.

[0024] Beneficial effects

[0025] The present application constructs a multi-layer memory wave spring by arranging a first wave spring and a second wave spring with different phase change temperatures, so that at the service temperature, the end of the spring maintains a softer martensite state for contact with the sealing pair to ensure a tight seal, and the middle part of the spring maintains an austenite state with superelasticity to provide better support for a long time.

[0026] Through the above technical solution, the present invention can effectively overcome the problems of poor sealing performance of existing wave spring sealing washers during use and elastic attenuation during long-term use, and can adjust the composition of the spring according to the temperature and pressure requirements of the environment to adapt to the size, temperature and pressure changes of the environment. It has strong applicability, especially for good sealing durability under extreme conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] The accompanying drawings, which constitute part of this application, are intended to provide a further understanding of this application. The exemplary embodiments and descriptions of this application are intended to explain this application and do not constitute an improper limitation on this application. In the accompanying drawings:

[0028] Figure 1 Schematic diagram of the structure of a single-layer annular closed wave spring in an embodiment of the present invention.

[0029] Figure 2 2 is a schematic structural diagram of a multi-layer memory wave spring in an embodiment of the present invention.

[0030] Figure 3 It is a schematic diagram of the processing and forming process of the multi-layer and wave spring according to an embodiment of the present invention.

[0031] In the figures, the meanings of the reference numerals are as follows:

[0032] First wave spring 1 and second wave spring 2. DETAILED DESCRIPTION

[0033] It should be noted that, in the absence of conflict, the embodiments and features of the embodiments in this application can be combined with each other. The present application will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0034] In the description of the present application, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present application. In addition, the terms "first" and "second" are used for descriptive purposes only and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the said features. In the description of the present application, "multiple" means two or more, unless otherwise clearly and specifically defined.

[0035] In the description of this application, it should be noted that, unless otherwise expressly specified or limited, the terms "installed," "connected," and "connected" should be understood in a broad sense. For example, they can refer to fixed connections, detachable connections, or integral connections; they can refer to mechanical connections, electrical connections, or mutual communication; they can refer to direct connections or indirect connections through an intermediate medium; they can refer to internal communication between two components or the interaction between two components. Those skilled in the art will understand the specific meanings of the above terms in this application based on specific circumstances.

[0036] Shape memory alloys have two phases: a high-temperature austenite phase and a low-temperature martensite phase. Austenite is the stable phase of shape memory alloys at high temperatures. Its crystal symmetry is high, and it exhibits superelasticity and a high modulus. For example, the commonly used TiNi shape memory alloy, when mechanically loaded in the austenitic state, can achieve a superelastic recoverable strain of approximately 8% and a modulus of approximately 80 GPa. Martensite is relatively soft, easily deformable, and has a low modulus. For example, when loaded in the martensitic state, the modulus of a TiNi shape memory alloy is approximately 40 GPa.

[0037] The embodiment of the present invention provides a composite spring based on the characteristics of different phases in shape memory alloys, that is, a multi-layer memory wave spring, which is composed of multiple single-layer wave springs stacked together. Figure 1 and Figure 2 Shown, including:

[0038] The first wave spring 1 is a single-layer annular closed-end memory alloy wave spring, and is located at both end surfaces of the entire multi-layer memory wave spring.

[0039] The second wave spring 2 is a single-layer annular closed-end memory alloy wave spring, and is located between the two end surfaces.

[0040] The first wave spring 1 and the second wave spring 2 are as shown in the attached Figure 1 The style shown is a single-layer thin ring-shaped elastic element with several peaks and valleys. Figure 2 As shown, a plurality of first wave springs 1 and a plurality of second wave springs 2 are stacked and fixed to form a multi-layer memory wave spring. Preferably, the first wave springs 1 and the second wave springs 2 are of the same size, and two adjacent single-layer wave springs are stacked and fixed with the peaks and troughs in contact.

[0041] In this embodiment, since the spring is used for sealing, both ends of the multi-layer memory wave spring are in contact with the sealing pair. In order to make the contact seal more reliable, the ends of the multi-layer memory wave spring should be kept in a relatively soft state. Therefore, the first wave spring 1 is in a martensite state at the service temperature of the multi-layer memory wave spring, that is, the phase transition temperature of the first wave spring 1 is higher than the applicable ambient temperature, and the middle section of the corresponding multi-layer memory wave spring mainly plays the role of providing elasticity. The middle section should maintain good elasticity. Therefore, the second wave spring 2 is in an austenite state at the service temperature of the multi-layer memory wave spring, that is, the phase transition temperature of the second wave spring 2 is lower than the applicable ambient temperature. As a preferred embodiment, the martensite phase transition starting temperature M of the first wave spring 1 is 0.14°C. s Higher than the service temperature of the multi-layer memory wave spring, the austenite phase transformation end temperature of the second wave spring 2 is A f Lower than the service temperature of multi-layer memory wave spring.

[0042] The multi-layer memory wave spring of this embodiment has the following significant advantages:

[0043] The two end surfaces of the multi-layer memory wave spring are made of martensitic shape memory alloy, which has the characteristic of low modulus and is easy to deform when in contact with the two end surfaces, ensuring high sealing performance when the component contacts other parts.

[0044] The middle section of the multi-layered shape memory wave spring is constructed in an austenitic state. When subjected to external forces, it undergoes significant deformation. Upon removal of the force, the deformation fully recovers, resulting in superelasticity, reaching up to 8%. Conventional wave spring gaskets, typically made of spring steel, typically have a yield point strain value between 0.2% and 0.7%. Therefore, a wave spring made of shape memory alloy can theoretically provide up to 10 times the recoverable strain of ordinary spring steel. This gives the gasket excellent cushioning, compensation, and shock absorption capabilities over a wider range of axial strains. It also avoids the force loss that often occurs with wave springs over time.

[0045] Furthermore, the midsection possesses exceptional superelasticity, effectively returning to its original state even after repeated loading and unloading. This feature effectively avoids the stress attenuation and sealing degradation experienced by traditional materials (such as chromium-nickel stainless steel) after flattening, significantly extending product life and reliability.

[0046] In the above embodiments, the composition of the spring between the two end surfaces has many different forms.

[0047] In certain preferred embodiments, at least one end has a first multi-layer structure formed by stacking multiple first wave springs 1. The first multi-layer structure is equivalent to a thicker washer, and the thickness of the first multi-layer structure is appropriately set according to the size of the accommodating space, thereby improving the spring's adaptability to various accommodating spaces.

[0048] In certain preferred embodiments, a second multilayer structure is formed between the two ends by stacking multiple second wave springs 2. The thicker the second multilayer structure, the greater the elastic force that the spring can provide. The thickness of the second multilayer structure can be reasonably set according to the required elastic force.

[0049] In certain preferred embodiments, a third multilayer structure is provided between the two ends, formed by stacking a plurality of first wave springs 1 and second wave springs 2. The first wave springs 1 in the third multilayer structure are located at least between every two second wave springs 2. The third multilayer structure employs an interlaced arrangement of the first wave springs 1 and the second wave springs 2, i.e., the third multilayer structure comprises both superelastic portions and low-modulus portions. Thus, the first wave springs 1 in the third multilayer structure serve as serial transition pieces for the second wave springs 2 adjacent to the first wave springs 1 at the ends. Compared to the first wave springs 1 at the ends, the first wave springs 1 in the third multilayer structure can provide a more direct buffering, compensating, and shock-absorbing effect on the second wave springs 2.

[0050] Because multi-layer memory wave springs are used in a variety of environments with varying temperatures, the phase transition temperatures of the first wave spring 1 and the second wave spring 2 need to be designed accordingly to ensure they exhibit the appropriate performance under the respective operating environments. Of course, in some embodiments, not all first wave springs 1 or second wave springs 2 have the same phase transition temperature; different phase transition temperatures can be set as needed.

[0051] In some preferred embodiments, the phase transition temperatures of all first wave springs 1 are the same, and / or the phase transition temperatures of all second wave springs 2 are the same. Such single-layer wave springs are relatively simple to manufacture and can be quickly mass-produced.

[0052] In certain preferred embodiments, the phase transition temperature of the first wave spring 1 gradually decreases along the central axis of the multi-layer memory wave spring, from the end surface toward its center. Because the phase transition temperature of the second wave spring 2 is lower than that of the first wave spring 1, the closer the first wave spring 1 is to the center of the multi-layer memory wave spring, the lower its phase transition temperature, i.e., the closer its phase transition temperature is to that of the second wave spring 2. This achieves a gradual transition in phase transition temperature, corresponding to a gradual transition in performance between two different phases. The performance at the ends of the multi-layer memory wave spring exhibits the highest proportion of softness, while the performance at the center of the multi-layer memory wave spring exhibits the highest proportion of superelasticity, creating a gradual transition in between, ensuring the stability and durability of the entire spring. In this embodiment, the phase transition temperature of the second wave spring 2 can be fixed or variable as needed.

[0053] In certain preferred implementations, the phase change temperature of the second wave spring 2 gradually decreases along the central axis of the multi-layer memory wave spring from the end surface to its center. With this arrangement, for a structure in which the first wave spring 1 is only distributed on the end side, the phase change temperature of the entire multi-layer memory wave spring shows a trend of decreasing from the end to the center. Such a spring is particularly suitable for occasions where the sealing pairs on both sides approach the multi-layer wave spring at high speed and the service temperature fluctuates. When the sealing pairs on both sides approach the multi-layer wave spring at high speed, the deformation first occurs from the two ends and gradually expands toward the center. Compared with the traditional single-temperature wave spring, the impact force caused by the rapid approach of the sealing pairs at both ends can be reduced. In addition, when the service temperature changes, the martensitic phase transformation starting temperature M in the second wave spring s The portion of the spring closest to the service temperature has the lowest critical stress required for deformation, thus providing a constant rebound force directed toward the sealing pairs on both sides over a wide temperature range. In this embodiment, the phase transition temperature of the first wave spring 1 can be fixed or variable as needed.

[0054] In some preferred implementations, for the use scenario of the vacuum flange sealing ring, the use environment is normal temperature, for example, the service temperature is 20-30°C, the martensite phase transition temperature Ms of the first wave spring 1 is 30-80°C, and the austenite phase transition temperature Af of the second wave spring 2 is -20-30°C.

[0055] In these preferred implementations, the material of the first wave spring 1 is a nickel-titanium alloy with a nickel content of 52.0-56 wt.%, and the material of the second wave spring 2 is a nickel-titanium alloy with a nickel content of 55-58.0 wt.%.

[0056] In some preferred implementations, for use scenarios such as aviation seals and oil well pipelines, the operating environment temperature is relatively high, for example, the service temperature is 200°C, the martensite phase transition temperature Ms of the first wave spring 1 is 250°C, and the austenite phase transition temperature Af of the second wave spring 2 is 180°C;

[0057] In these preferred embodiments, the material of the first wave spring 1 is titanium-nickel-palladium high-temperature shape memory alloy, the nickel content of the titanium-nickel-palladium high-temperature shape memory alloy is 18-48wt.%, the Ti content is 40-46wt.%, and the palladium content is 9-47wt.%. The material of the second wave spring 2 is nickel-titanium alloy with a nickel content of 55-58.0wt.%.

[0058] In some preferred implementations, for use scenarios in cold areas, the ambient temperature is low, for example, the service temperature is -30°C, the martensite transformation temperature Ms of the first wave spring 1 is 0°C, and the austenite transformation temperature Af of the second wave spring 2 is -40°C.

[0059] In these preferred implementations, the first wave spring 1 is made of nickel-titanium alloy with a nickel content of 52.0-56 wt.%, and the second wave spring 2 is made of nickel-titanium-iron alloy with a nickel content of 55-58.0 wt.% and an Fe content of 3-10.0 wt.%.

[0060] like Figure 3 As shown, a method for preparing a multi-layer memory wave spring according to each of the above embodiments includes the following steps:

[0061] Step 1: Prepare a single-layer annular closed first wave spring 1.

[0062] Step 2: Prepare a single-layer annular closed second wave spring 2.

[0063] Step 3: stack the layers in a manner of arranging the first wave springs 1 at both ends and the second wave spring 2 between the two ends and perform metallurgical bonding between the layers.

[0064] The first wave spring 1 is in a martensite state at the service temperature of the multi-layer memory wave spring, and the second wave spring 2 is in an austenite state at the service temperature of the multi-layer memory wave spring.

[0065] The above preparation method is simple and efficient, and each step is batch-produced separately. For a combination of single-layer wave springs with different phase change temperatures, they need to be stacked in sequence according to the design requirements of the phase change temperature in step 3.

[0066] The preparation method comprises the following steps: using a nickel-titanium shape memory alloy sheet with a nickel content of 53.0-55.2 wt.% as the raw material for the first wave spring 1 and a nickel-titanium-based shape memory alloy sheet with a nickel content of 55.3-57.0 wt.% as the raw material for the second wave spring 2, maintaining the phase transition temperature of each wave spring constant, and the first wave spring 1 being located only at the end.

[0067] Step (1), preparing the first wave spring 1:

[0068] A nickel-titanium shape memory alloy with a nickel content of 53.0-55.2wt.% is used, hot-rolled at 700-1000℃ to a 0.35mm plate, then hot-stamped at 700-1000℃ to form a ring-shaped planar structure, and then hot-stamped twice at the same temperature to form a wavy annular single-layer wave spring.

[0069] Here, the stamping step specifically includes: stamping the alloy sheet for the first time at 800-1000°C / 150MPa to form a Φ50±0.1mm annular planar structure, and then stamping it for the second time at the same temperature and 180MPa pressure to form a wavy structure with a wave height of 1.5mm and a spacing of 3.0±0.1mm.

[0070] Step (2), preparing a second wave spring:

[0071] A nickel-titanium-based shape memory alloy with a nickel content of 55.3-57.0wt.% is used, which is hot-rolled at 700-1000℃ to a 0.35mm plate. It is first hot-stamped at 700-1000℃ to form a ring-shaped planar structure, and then hot-stamped again at the same temperature to form a wavy structure.

[0072] Here, the stamping step specifically includes stamping the alloy sheet at 800-1000°C / 150MPa for the first time to form a Φ50±0.1mm annular planar structure, and then stamping it again at the same temperature and 200MPa pressure to form a wavy structure with a wave height of 2.2mm and a spacing of 3.8±0.1mm.

[0073] Step (3), stacking assembly:

[0074] The three layers of wave springs are stacked along the axial direction of the springs in the structure of first wave spring 1 - second wave spring 2 - first wave spring 1, and are fixed with a mold around them.

[0075] Step (4), vacuum diffusion welding:

[0076] The sample was placed in a vacuum annealing furnace and the vacuum degree was reduced to 5×10 -3 Pa, heat to 700-1100℃ at 20℃ / min, and then keep warm for 2-3h under 5MPa pressure.

[0077] After measurement, the thickness of the interface diffusion layer between two adjacent wave springs is 3.8μm, the oxygen content is 428ppm, and the interlayer shear strength is 285MPa.

[0078] The multilayer memory wave spring obtained by the above method exhibits a gradient stiffness characteristic when the axial compression deformation is 10%, with an initial stiffness of 12-15 N / mm, a stiffness of 32-35 N / mm in the deep compression stage, a residual deformation of ≤0.2%, a sealing contact pressure fluctuation range of <±15%, and a fatigue life of ≥5×10 6 times, showing good durability and adaptability.

[0079] This gradient stiffness characteristic stems from the fact that the different layers of a multi-layered memory wave spring have different moduli during compression. During the initial loading phase, the first wave spring, with its low modulus, first contacts the sealing pairs on both sides, resulting in a lower stiffness. As the compression deformation increases, the second wave spring in the middle begins to deform under force. Because the second wave spring is made of a high-modulus shape memory alloy with a lower phase transition temperature, the second stage of deformation exhibits a higher modulus. This gradient stiffness characteristic mitigates the impact of rapid loading of the sealing pairs on both sides, thereby improving assembly safety.

[0080] In some embodiments, two to four or more multi-layered memory wave springs, incorporating them into a sealing system, can be installed in parallel or in phase. These springs can be connected in series or in parallel to ensure a stable and reliable sealing system.

[0081] The above are merely embodiments of the present application and are not intended to limit the present application. For those skilled in the art, the present application may have various changes and variations. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present application should all be included within the scope of the claims of the present application.

Claims

1. A multi-layer memory wave spring, characterized in that: include: The first wave spring is a single-layer annular closed-end memory alloy wave spring located at both end surfaces of the entire multi-layer memory wave spring; The second wave spring is a single-layer annular closed-end memory alloy wave spring, located between the two end surfaces; The first wave spring is in a martensite state at a service temperature of the multi-layer memory wave spring, and the second wave spring is in an austenite state at a service temperature of the multi-layer memory wave spring.

2. The multi-layer memory wave spring according to claim 1, characterized in that: The martensitic transformation starting temperature M of the first wave spring s Higher than the service temperature of the multi-layer memory wave spring, the austenite phase transformation end temperature of the second wave spring is A f Lower than the service temperature of multi-layer memory wave spring.

3. The multi-layer memory wave spring according to claim 1, characterized in that: At least one end side thereof has a first multi-layer structure formed by stacking a plurality of first wave springs.

4. A multi-layer memory wave spring according to any one of claims 1 to 3, characterized in that: A second multi-layer structure formed by stacking a plurality of second wave springs is provided between the two end sides.

5. The multi-layer memory wave spring according to claim 4, characterized in that: A third multi-layer structure formed by stacking a plurality of first wave springs and second wave springs is provided between the two end sides. The first wave springs in the third multi-layer structure are at least located between every two second wave springs.

6. The multi-layer memory wave spring according to claim 4, characterized in that: The phase transition temperatures of all the first wave springs are the same, or the phase transition temperatures of the first wave springs gradually decrease along the central axis of the multi-layer memory wave spring from the end surface to the center thereof.

7. The multi-layer memory wave spring according to claim 4, characterized in that: The phase transition temperatures of all the second wave springs are the same, or the phase transition temperatures of the second wave springs gradually decrease along the central axis of the multi-layer memory wave spring from the end surface to the center thereof.

8. A method for preparing a multi-layer memory wave spring, characterized in that: include: Prepare a single-layer annular closed first wave spring; Prepare a single-layer annular closed second wave spring; The first wave springs are arranged at both ends and the second wave spring is arranged between the two ends, and the layers are metallurgically bonded; Wherein, the first wave spring is in a martensite state at the service temperature of the multi-layer memory wave spring, and the second wave spring is in an austenite state at the service temperature of the multi-layer memory wave spring.

9. The preparation method according to claim 8, characterized in that The interlayer metallurgy is carried out under the following conditions: temperature 700-1100°C, vacuum degree ≤ 5×10 -3 Pa, holding time 2-3 hours, after welding, an interdiffusion layer with a thickness of 2-5 μm is formed.

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