A composite sealing ring suitable for extreme temperature alternating conditions and its molding method

Abstract

This invention relates to the field of composite sealing ring molding technology, and more particularly to a composite sealing ring suitable for extreme temperature alternating conditions and its molding method. The method includes: optimizing the layer thickness ratio of the sealing ring; determining the structural dimensions based on the layer thickness ratio and the standard thickness of the sealing ring to fabricate an annular metal support skeleton; pre-treating the metal support skeleton; mixing metal powder and non-metal powder made from the metal support skeleton material in different proportions to obtain a transition layer, and laying it on the inner side of the metal support skeleton in a gradient manner; laying the mixed wear-resistant layer powder on the inner side of the transition layer; closing the mold for integrated pressing and sintering; after sintering, performing radial forging treatment; performing cryogenic treatment and wear resistance testing, and adjusting the set parameters based on the test data. The composite sealing ring prepared by this invention has a compact structure, which can ensure structural stability and sealing performance under frequent extreme temperature alternating conditions.

Description

Technical Field

[0001] This invention relates to the field of composite sealing ring molding technology, and in particular to a composite sealing ring suitable for extreme temperature alternation conditions and its molding method. Background Technology

[0002] With the rapid development of the global liquefied natural gas (LNG) industry and the rise of emerging fields such as liquid hydrogen and aerospace fuel, cryogenic butterfly valves, as key equipment in LNG receiving terminals, LNG carriers, air separation units, and major national energy projects, require design temperatures as low as -196℃ or even -254℃. Market demand is strong and the process of domestic substitution is urgent, making it one of the core equipment for ensuring energy strategic security.

[0003] Under such harsh operating conditions, the composite sealing ring, as the core component for achieving reliable sealing, directly determines the sealing level and service life of the valve in cryogenic environments. However, existing composite sealing rings generally employ a metal-non-metal laminated adhesive structure, which presents two inherent challenges in cryogenic environments: first, the adhesive becomes brittle and fails at extreme low temperatures, leading to interlayer debonding and disintegration; second, the significant difference in linear expansion coefficients between metal and non-metal materials, such as graphite and polytetrafluoroethylene, causes uneven shrinkage and distortion of the sealing surface, resulting in a severe drop in sealing pressure and even leakage. Furthermore, conventional non-metallic materials are prone to hardening and cracking at low temperatures, experiencing cold flow and stress relaxation, while the metal matrix also exhibits low-temperature brittleness, further exacerbating the risk of sealing failure. Therefore, how to overcome the reliance on traditional adhesives, solve the problems of interfacial peeling and thermal strain incompatibility caused by thermal expansion mismatch, and develop a new composite sealing structure with adaptive compensation capabilities and reliable interlayer bonding has become the core direction of technological innovation and a key breakthrough for industrial upgrading in cryogenic butterfly valves.

[0004] Chinese Patent Application Publication No. CN117685380A discloses a composite sealing ring suitable for cryogenic environments such as liquid hydrogen, its preparation method, and a butterfly valve constructed therefrom. The sealing ring comprises several layers of metal and non-metal layers stacked together with intervals between them. Each metal and non-metal layer has several pin holes through which pins can pass. A pin is installed in each pin hole, passing through each metal and non-metal layer and connecting them into a single unit. The non-metal layer is made of 54%–50% polyimide resin and 46%–50% graphite by mass. The composite sealing ring of this invention will not crack or deform when used in cryogenic environments such as liquid hydrogen, ensuring good sealing performance even at low temperatures. This highlights the problem with existing technologies, which suffer from simple composite structures and reliance on simple mechanical connections between different material layers. This leads to interface peeling of the sealing ring under frequent extreme temperature alternation conditions, resulting in decreased sealing performance. Summary of the Invention

[0005] Therefore, the present invention provides a composite sealing ring suitable for extreme temperature alternating conditions and its molding method, in order to overcome the problems in the prior art where the composite form of the sealing ring is simple and the interface bonding between different material layers relies only on simple mechanical connection, which easily leads to interface peeling of the sealing ring under multiple extreme temperature alternating conditions, resulting in a decrease in sealing performance.

[0006] To achieve the above objectives, in one aspect, the present invention provides a method for forming a composite sealing ring suitable for extreme temperature alternation conditions, comprising:

[0007] Step S1: Obtain deformation data and stress distribution data of the metal support skeleton material and non-metallic material of the composite sealing ring under the target extreme temperature conditions, respectively.

[0008] Step S2: Determine the layer thickness ratio of the sealing ring based on the deformation data of the metal support skeleton material and the deformation data of the non-metallic material;

[0009] Step S3: Determine the structural dimensions of the annular metal support frame based on the layer thickness ratio and the standard thickness of the sealing ring to fabricate the annular metal support frame;

[0010] Step S4: After pre-treating the annular metal support frame, place it in a pre-pressing mold, mix the metal powder and non-metal powder in the corresponding proportion to obtain a transition layer, and lay it on the inner side of the outer ring of the metal support frame in a gradient laying manner.

[0011] Step S5: The mixed wear-resistant layer powder is laid on the inner side of the transition layer to form a pre-compressed part;

[0012] Step S6: The pre-pressed parts in the pre-pressing mold are sequentially pressed and sintered in one piece to obtain sintered parts;

[0013] Step S7: Determine forging parameters based on the pressing parameters, pressing dimensions and sintering dimensions corresponding to the sintered part, so as to perform radial forging treatment on the sintered part to form a composite sealing ring;

[0014] Step S8: The fabricated composite sealing ring is subjected to immersion cryogenic treatment and wear resistance testing in sequence, and the test data of the composite sealing ring is obtained to correct the pressing parameters and obtain the composite molded part.

[0015] Alternatively, the layer thickness ratio in step S1 can be adjusted to re-prepare the composite molded part.

[0016] Furthermore, the layer thickness ratio is determined based on the ratio of the maximum deformation of the metal support skeleton material to the average deformation of the non-metallic material, and the number of transition layers is determined based on the layer thickness ratio and the thickness of the metal skeleton of the composite molded part.

[0017] Further, step S3 includes,

[0018] Step S31: Determine the standard wall thickness of the annular metal support frame according to the layer thickness ratio and the standard thickness of the sealing ring, so as to process the metal blank of the metal support frame material into an annular metal support frame with a C-shaped cross section.

[0019] Step S32, heat treatment is performed on the annular metal support frame, including solution treatment and aging heat treatment;

[0020] The extension length of the upper and lower end faces of the annular metal support frame is half of the standard wall thickness.

[0021] Furthermore, in step S4, the number of transition layers is determined based on the layer thickness ratio, so that the transition layer is divided into several layers.

[0022] The mixing ratio of metal powder and non-metal powder in each layer is determined based on the number of transition layers, and the proportion of metal powder in the transition layer closer to the outer ring of the annular metal support skeleton is higher than that in the transition layer farther from the outer ring of the annular metal support skeleton.

[0023] Further, step S7 includes:

[0024] Step S71: Obtain the pressing size and sintering size to determine the sintering-air ratio based on the pressing size and sintering size;

[0025] Step S72: Determine the pressing efficiency based on the dimensions before pre-pressing and the dimensions of the pressed part after integrated pressing;

[0026] Step S73: Determine the additional forging coefficient based on the burn-out ratio and the pressing efficiency, and then determine the forging parameters based on the additional forging coefficient and the preset forging parameters.

[0027] Further, step S8 includes:

[0028] Step S81: Obtain interlayer separation data and leakage data of the composite sealing ring;

[0029] Step S82: Calculate the cumulative process loss based on the interlayer separation data to determine whether the forging exceeds the limit;

[0030] Step S83: Calculate the temperature runaway factor based on the leakage data;

[0031] Step S84: Determine the molding quality of the composite sealing ring based on the accumulated process loss and temperature runaway factor to select the corresponding adjustment strategy.

[0032] Furthermore, in step S84,

[0033] If the cumulative process loss is greater than or equal to a preset loss threshold, the forging is deemed to have exceeded the limit. The pressing parameters are then corrected based on the cumulative process loss to obtain the composite molded part.

[0034] If the cumulative process loss is less than a preset loss threshold and the temperature runaway factor is greater than or equal to a preset temperature control threshold, the layer thickness ratio is determined to be unbalanced, and the layer thickness ratio is adjusted to re-prepare the composite molded part.

[0035] Furthermore, the pressing parameters include the molding pressure of the integrated pressing, and the correction value of the molding pressure is calculated based on the current molding pressure value and the cumulative process loss.

[0036] Furthermore, the layer thickness ratio is adjusted to increase the number of transition layers, wherein the temperature runaway factor is positively correlated with the number of transition layers.

[0037] On the other hand, the present invention also provides a composite sealing ring, which is prepared by the above-described molding method for composite sealing rings suitable for extreme temperature alternation conditions, comprising:

[0038] Circular metal support frame;

[0039] Several transition layers are set inside the annular metal support frame;

[0040] A wear-resistant layer is set inside the transition layer;

[0041] An elastic compensation device, located on the outside of the annular metal support frame, is used to provide preload through its own elastic energy storage.

[0042] Compared with the prior art, the beneficial effects of the present invention are that the present invention uses a precision molding and sintering integrated molding process to prepare a composite sealing ring suitable for extreme temperature alternating conditions. The metal skeleton pretreatment, gradient powder laying, room temperature pre-pressing molding and high temperature sintering densification in the mold are completed continuously in the same process, eliminating intermediate transfer, secondary molding and multiple bonding steps, which greatly simplifies the process flow and improves production efficiency and dimensional accuracy.

[0043] Furthermore, this invention fundamentally solves the problems of delamination, debonding, and cracking caused by the mismatch of thermal expansion coefficients in traditional metal and non-metal composite sealing rings by using a gradient-set transition layer for continuous integrated sintering, thereby significantly improving structural stability and thermal cycle life.

[0044] Furthermore, the present invention effectively eliminates molding aids and internal pores through a staged high-temperature sintering process, resulting in a higher density and stronger interfacial bonding of the sealing ring. Combined with the elastic support of the metal skeleton and the active elastic compensation device of the outer ring, the product still has excellent toughness, rebound compensation capability, low friction characteristics and high sealing reliability even in an ultra-low temperature environment of -196℃.

[0045] Furthermore, by conducting cryogenic and wear resistance tests before delivery, this invention verifies the product quality of the sealing ring and enables dynamic parameter feedback and adjustment for subsequent batches. On the other hand, it allows unsuitable sealing rings to be downgraded for use in relatively mild temperature conditions, thereby indirectly improving the product qualification rate and reducing production costs. Attached Figure Description

[0046] Figure 1 This is a flowchart of the molding method for the composite sealing ring applicable to extreme temperature alternating conditions according to the present invention;

[0047] Figure 2 This is a flowchart of step S3 of the molding method of the composite sealing ring applicable to extreme temperature alternating conditions of the present invention;

[0048] Figure 3 This is a flowchart of step S7 of the molding method of the composite sealing ring applicable to extreme temperature alternating conditions of the present invention;

[0049] Figure 4 This is a flowchart of step S8 of the molding method of the composite sealing ring applicable to extreme temperature alternating conditions of the present invention;

[0050] Figure 5 This is a schematic diagram of the composite sealing ring of the present invention, applicable to extreme temperature alternation conditions;

[0051] Figure 6 This is a cross-sectional schematic diagram of the composite sealing ring of the present invention applicable to extreme temperature alternation conditions;

[0052] In the figure, 1-metal support frame; 2-transition layer; 3-wear-resistant layer; 4-elastic compensation device. Detailed Implementation

[0053] To make the objectives and advantages of the present invention clearer, the present invention will be further described below with reference to embodiments; it should be understood that the specific embodiments described herein are merely for explaining the present invention and are not intended to limit the present invention.

[0054] Preferred embodiments of the present invention will now be described with reference to the accompanying drawings. Those skilled in the art should understand that these embodiments are merely illustrative of the technical principles of the present invention and are not intended to limit the scope of protection of the present invention.

[0055] It should be noted that in the description of this invention, the terms "upper", "lower", "left", "right", "inner", "outer", etc., which indicate directions or positional relationships, are based on the directions or positional relationships shown in the accompanying drawings. This is only for the convenience of description and is not intended to indicate or imply that the device or element must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, it should not be construed as a limitation of this invention.

[0056] Furthermore, it should be noted that, in the description of this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0057] In this embodiment, the composite sealing ring is used in the triple eccentric butterfly valve to ensure that the triple eccentric butterfly valve maintains stable sealing performance under extreme temperature difference conditions of alternating hot and cold.

[0058] Please see Figure 1 The flowchart shown is a method for forming a composite sealing ring applicable to extreme temperature alternating conditions according to the present invention, including:

[0059] Step S1: Obtain deformation data and stress distribution data of the metal support skeleton material and non-metallic material of the composite sealing ring under the target extreme temperature conditions, respectively.

[0060] Specifically, in this embodiment, the composite sealing ring suitable for extreme temperature alternating conditions is mainly made of a ring-shaped metal support skeleton and several composite materials of metal and non-metal mixed on the inner side of the skeleton. In order to make the prepared composite sealing ring have a stable structure and avoid deformation causing poor sealing effect, extreme working condition tests are usually carried out on the metal support skeleton material and non-metal materials used to prepare the composite sealing ring under the target extreme temperature conditions. Deformation data and stress distribution data of metal support skeleton material samples and non-metal material samples under the highest and lowest temperature conditions are obtained respectively. In this embodiment, the lowest temperature is set to -253°C for liquid hydrogen transportation conditions, and the highest temperature is set to the human critical wet-bulb temperature, i.e., 35°C.

[0061] In this embodiment, it is preferable to obtain the high-temperature deformation and low-temperature deformation of metal support skeleton material blocks and non-metallic material blocks under the highest and lowest temperature conditions, as well as the stress uniformity data under the corresponding conditions.

[0062] Step S2: Determine the layer thickness ratio of the sealing ring based on the deformation data of the metal support skeleton material and the deformation data of the non-metallic material;

[0063] Step S3: Determine the structural dimensions of the annular metal support frame based on the layer thickness ratio and the standard thickness of the sealing ring to fabricate the annular metal support frame;

[0064] Please see Figure 2 The diagram shows a flowchart of step S3 in the molding method of the composite sealing ring applicable to extreme temperature alternating conditions according to the present invention. Specifically, step S3 includes:

[0065] Step S31: Determine the standard wall thickness of the annular metal support frame according to the layer thickness ratio and the standard thickness of the sealing ring, so as to process the metal blank of the metal support frame material into an annular metal support frame with a C-shaped cross section.

[0066] Specifically, the layer thickness ratio is determined based on the ratio of the maximum deformation of the metal support skeleton material to the average deformation of the non-metallic material, and the number of transition layers is determined based on the layer thickness ratio and the thickness of the metal skeleton of the composite molded part.

[0067] Specifically, the maximum deformation of the metal skeleton material under the highest and lowest temperature conditions is denoted by M, and the average deformation of the non-metallic material under the same conditions is denoted by N. The layer thickness ratio, i.e., the ratio of the transition layer thickness to the metal support skeleton thickness, is denoted by T, which is... Where K is an empirical coefficient and K=1.1; the standard thickness of the sealing ring, i.e., the radial height, is denoted by H, and is determined based on the depth of the mounting groove and the diameter of the butterfly plate. It is a design value. The height of the sealing ring, i.e., the axial height, is denoted by S, and is determined based on the width of the mounting groove reserved in the valve body. It is also a design value. Preferably, H=20mm and S=35mm are set. Then the standard wall thickness of the metal support frame (denoted by R) is... .

[0068] In this embodiment, the cone angle value of the sealing surface is determined based on the friction coefficient of the wear-resistant layer.

[0069] Specifically, the cone angle of the sealing surface is the angle between the extensions of the two sealing surfaces in the cross-section of the sealing ring (denoted by α), and the friction coefficient of the wear-resistant layer is denoted by f. m If tan(α) ≤ f, then m It is understandable that butterfly valves used in cryogenic conditions are mostly triple-eccentric butterfly valves. In triple-eccentric butterfly valves, the sealing pair formed by the butterfly plate and the sealing ring achieves sealing of the medium through mutual friction and wedging. After the valve is closed, it can be locked in the sealing position by friction and will not come off on its own. However, if the cone angle is too large and the wedging force is too strong, it is easy to cause the valve to jam or the opening and closing torque to be too large, making operation difficult. If the cone angle is too small, it may not be able to provide sufficient sealing pressure, or even achieve self-locking. Preferably, during the initial molding, the cone angle is set to the maximum value within this range, i.e., tan(α) = f m .

[0070] Step S32 involves heat treating the annular metal support frame, including solution treatment and aging heat treatment. This is applicable to any existing technology for stress relief of metal parts, as long as it can reduce the material stress of the annular metal support frame. All of these are applicable to this embodiment and will not be elaborated here.

[0071] The extension length of the upper and lower end faces of the annular metal support frame is half the standard thickness of the sealing ring.

[0072] In one specific embodiment, based on the structural dimensions determined by calculation, the metal blank is processed into a C-shaped annular metal support skeleton, which is then subjected to solution treatment and aging heat treatment. High-temperature solution treatment eliminates internal stress and homogenizes the composition, followed by medium-low temperature aging to precipitate strengthening phases. Ultimately, the skeleton acquires excellent ultra-low temperature toughness, strength, and elastic resilience to meet the support requirements of ultra-low temperature sealing rings. Subsequently, it undergoes pretreatment before being molded, pressed, and sintered, specifically as follows:

[0073] First, white corundum sand is used for sandblasting to roughen the surface and obtain a suitable surface roughness.

[0074] Next, ultrasonic cleaning with acetone and anhydrous ethanol was performed to remove surface oil and impurities;

[0075] Then, high-temperature activation is performed in a vacuum or protective atmosphere to eliminate the surface oxide layer and improve surface activity.

[0076] Pretreatment enhances the interfacial bonding strength between the metal skeleton and the transition layer, preventing delamination, debonding, and cracking during ultra-low temperature thermal cycling. The solutions treatment, aging heat treatment, and pretreatment processes involved in the metal support skeleton are all existing technologies and will not be elaborated upon here.

[0077] Step S4: After pre-treating the annular metal support frame, place it in a pre-pressing mold, mix the metal powder and non-metal powder in the corresponding proportion to obtain a transition layer, and lay it on the inner side of the outer ring of the metal support frame in a gradient laying manner.

[0078] Specifically, in step S4, the number of transition layers is determined based on the layer thickness ratio, so that the transition layer is divided into several layers.

[0079] The mixing ratio of metal powder and non-metal powder in each layer is determined based on the number of transition layers, and the proportion of metal powder in the transition layer closer to the outer ring of the annular metal support skeleton is higher than that in the transition layer farther from the outer ring of the annular metal support skeleton.

[0080] Specifically, the number of transition layers, L, is positively correlated with the thickness of the transition layer. That is, the thicker the transition layer, the more layers are needed to achieve a more linear transition between the thermal expansion coefficients of different materials. , This is for rounding up.

[0081] Step S5: The mixed wear-resistant layer powder is laid on the inner side of the transition layer to form a pre-compressed part;

[0082] It is understandable that metals and non-metals have different coefficients of thermal expansion. If two different types of materials are directly combined using a simple mechanical connection, they are prone to different deformations due to their different coefficients of thermal expansion when subjected to extreme temperature conditions and multiple ultra-low temperature and normal temperature cycles. This can lead to interface delamination, which in turn causes a decrease in sealing performance, media leakage, and a sudden increase in valve opening and closing torque. Therefore, it is necessary to solve the problem of the different coefficients of thermal expansion between metals and non-metals.

[0083] Specifically, the proportion of metal powder in the transition layer near the outer ring of the annular metal support skeleton is higher than that in the transition layer far from the outer ring of the annular metal support skeleton.

[0084] In this embodiment, metal and non-metal materials are uniformly mixed and laid sequentially according to a predetermined layer thickness ratio using a gradient powder spreading method. Based on calculation results, the transition layer consists of three layers, arranged from the side closest to the metal support skeleton towards the center: a first transition layer with a content of 70% metal powder + 30% non-metal powder, a second transition layer with 50% metal powder + 50% non-metal powder, and a third transition layer with 30% metal powder + 70% non-metal powder. The wear-resistant layer powder is laid on the inner side of the third transition layer, thereby achieving a continuous transition in the coefficient of thermal expansion from the metal substrate to the polymer sealing layer, eliminating interfacial thermal stress, and avoiding delamination, cracking, and debonding under thermal cycling.

[0085] In the proportion of other transition layers, as long as the uniform transition stress can be met, it is acceptable. In practice, the proportion of metal powder in the transition layer near the outer ring of the annular metal support skeleton is higher than that in the transition layer far from the outer ring of the annular metal support skeleton, which can achieve a gradual change in stress. Typically, the proportion of metal can be set to uniformly decrease from 100% in the outermost skeleton to 0% in the innermost wear-resistant layer.

[0086] The pretreated metal support frame is placed in a ring mold, which is vertically fixed on a high-speed rotating turntable driven by a motor. The centrifugal force of the high-speed rotation ensures the uniformity and relative stability of the components during powder spreading. Gradual powder spreading is performed according to the aforementioned proportions and sequence. Before mixing each layer of powder, appropriate amounts of additives such as powder dispersants, lubricants, and binders are added to aid in better powder mixing. This embodiment does not limit the additives used in the metal-nonmetal composite material; any additive that helps the metal powder and nonmetal mix more evenly is acceptable and will not be elaborated upon here.

[0087] Step S6: The pre-pressed parts in the pre-pressing mold are sequentially pressed and sintered in one piece to obtain sintered parts;

[0088] In this embodiment, the material of the annular metal support skeleton is the same as that of the metal powder, which is a nickel-based alloy. The non-metallic powder is polyimide, and the wear-resistant layer is modified polytetrafluoroethylene. Pre-pressing is performed at room temperature. Hydraulic equipment is used to slowly apply pressure to the mold to press the powder of the transition layer and the wear-resistant layer into an integral blank. After the pressure reaches the set value, pressure is held. Preferably, the set pressure is 15MPa and the holding time is 60S.

[0089] Maintain pressure and add atmosphere protection equipment for integrated sintering. Heat to the first sintering temperature of 200℃ at a heating rate of 5℃ / min and hold for 30min to remove moisture and additives from the mold.

[0090] Continue to raise the temperature to the second sintering temperature of 320℃ at a rate of 3℃ / min and hold for 30min to soften and initially bond the powders in the transition layer.

[0091] Continue heating at a rate of 2℃ / min to 380℃ and hold for 90min to allow the wear-resistant layer powder to melt and recrystallize and the transition layer powder to sinter. At this time, the polymer interface of the wear-resistant layer diffuses and combines with the transition layer.

[0092] Step S7: Determine forging parameters based on the pressing parameters, pressing dimensions and sintering dimensions corresponding to the sintered part, so as to perform radial forging treatment on the sintered part to form a composite sealing ring;

[0093] Please see Figure 3 The diagram shows a flowchart of step S7 of the method for forming a composite sealing ring applicable to extreme temperature alternating conditions according to the present invention. Specifically, step S7 includes...

[0094] Step S71: Obtain the pressing size and sintering size to determine the sintering-air ratio based on the pressing size and sintering size;

[0095] Step S72: Determine the pressing efficiency based on the dimensions before pre-pressing and the dimensions of the pressed part after integrated pressing;

[0096] Step S73: Determine the additional forging coefficient based on the burn-out ratio and the pressing efficiency, and then determine the forging parameters based on the additional forging coefficient and the preset forging parameters.

[0097] Specifically, the pressing parameters include the forming pressure of the integrated pressing, the forging parameters include the forging pressure of the radial forging process, and the preset forging parameters include the preset forging pressure.

[0098] It is understandable that during the integrated pressing and sintering process, the powder layers of the sealing ring to be formed will fully combine, and the volume will continuously decrease under the action of pressing. Therefore, in this embodiment, the sealing ring to be formed will have two dimensions during the integrated sintering stage, namely the pressed dimension A before sintering and the sintered dimension B after sintering.

[0099] Then the air-to-burn ratio X is ;

[0100] If the dimensions before pre-compression are denoted by C, then the compression efficiency is denoted by Y, which is... And Y∈(0,1);

[0101] If the preset forging pressure is represented by F0, then the additional forging coefficient is represented by Z, which is Z=XY.

[0102] Forging pressure, denoted by F2, is F2 = F0 × (1 + Z).

[0103] The composite sealing ring initially formed in the mold was further forged using a ring rolling device to improve the bonding between the metal support skeleton, the transition layer and the wear-resistant layer.

[0104] Step S8: The fabricated composite sealing ring is subjected to immersion cryogenic treatment and wear resistance testing in sequence, and the test data of the composite sealing ring is obtained to correct the pressing parameters and obtain the composite molded part.

[0105] Alternatively, the layer thickness ratio and sealing surface cone angle value in step S1 can be adjusted to re-prepare the composite molded part.

[0106] Specifically, in this embodiment, the immersion cryogenic treatment involves completely immersing the composite sealing ring in liquid nitrogen for 10 hours.

[0107] The wear resistance test specifically involves installing the composite sealing ring in the butterfly valve and placing it again in a liquid nitrogen environment, and then performing several high-pressure / pulsating pressure valve plate opening and closing tests on it.

[0108] Please see Figure 4 The diagram shows a flowchart of step S8 in the method for forming a composite sealing ring applicable to extreme temperature alternating conditions according to the present invention. Specifically, step S8 includes:

[0109] Step S81: Obtain interlayer separation data and leakage data of the composite sealing ring;

[0110] Step S82: Calculate the cumulative process loss based on the interlayer separation data to determine whether the forging exceeds the limit;

[0111] Step S83: Calculate the temperature runaway factor based on the leakage data;

[0112] Step S84: Determine the molding quality of the composite sealing ring based on the accumulated process loss and temperature runaway factor to select the corresponding adjustment strategy.

[0113] Specifically, in step S84,

[0114] If the cumulative process loss is greater than or equal to a preset loss threshold, the forging is deemed to have exceeded the limit. The pressing parameters are then corrected based on the cumulative process loss to obtain the composite molded part.

[0115] If the cumulative process loss is less than a preset loss threshold and the temperature runaway factor is greater than or equal to a preset temperature control threshold, the layer thickness ratio is determined to be unbalanced, and the layer thickness ratio is adjusted to re-prepare the composite molded part.

[0116] If the cumulative process loss is less than a preset loss threshold and the temperature runaway factor is less than a preset temperature control threshold, the process is deemed reasonable, and there is no need to adjust the process parameters of the sealing ring. The composite molded part is then prepared according to the process parameters of each step.

[0117] Specifically, the correction value of the molding pressure is calculated based on the current molding pressure value and the cumulative process loss.

[0118] Specifically, the layer thickness ratio is adjusted to increase the number of transition layers, wherein the temperature runaway factor is positively correlated with the number of transition layers.

[0119] In this embodiment, interlayer separation data is represented by the delamination gap. The delamination gap of the composite sealing ring after cryogenic treatment characterizes the cumulative process loss. That is, by ultrasonic testing of the composite structure of the sealing ring, it is found that there is local delamination between the metal support skeleton and the transition layer, and the delamination gap is 0.6 μm. Preferably, the delamination threshold is set to 0.5 μm. The cumulative process loss is the delamination gap divided by the delamination threshold. The preset loss threshold is 1, indicating that the thermal strain incompatibility between the metal support skeleton and the transition layer has caused interface peeling and leakage channels exist. The correction value of the current molding pressure F1 is then determined. That is The sealing ring is prepared using the adjusted process parameters until the cumulative process loss is less than the preset loss threshold and the temperature runaway factor is less than the preset temperature control threshold, and then the composite molded part is prepared.

[0120] In another embodiment of this invention, the leakage data of the composite sealing ring after wear resistance testing is used to characterize the temperature runaway factor. Specifically, the leakage rate of the butterfly valve equipped with the composite sealing ring, measured by helium mass spectrometry leak detection, reached 1.2 × 10⁻⁶ after 500 wear resistance opening and closing tests. -6 Pa·m³ / s, preferably, the sealing threshold is set to 1×10⁻⁶. -6 Pa·m³ / s, the temperature runaway factor is the leakage rate divided by the sealing threshold. The preset temperature control threshold is set to 1, indicating that the wear-resistant layer has experienced relatively severe wear, but its delamination gap is less than the delamination threshold. At this time, it indicates the layer thickness ratio. Adjusting and increasing the thickness of the transition layer and correspondingly increasing the number of layers can also reduce the cone angle within the process allowable range, so as to reduce the friction between the sealing pairs while ensuring that the thermal expansion coefficient transition is sufficiently linear. Obviously, the higher the leakage rate, the more necessary it is to increase the number of layers in the transition layer. Under normal circumstances, the thickness of the transition layer is set to 120% of the original thickness for a single adjustment, the number of layers is increased accordingly, and the cone angle is reduced to 90% of the original cone angle value, and each adjustment is rounded up within the usable accuracy range.

[0121] Understandably, the sealing ring is prepared using the adjusted process parameters until the cumulative process loss is less than the preset loss threshold and the temperature runaway factor is less than the preset temperature control threshold, and then the composite molded part is prepared.

[0122] The metallic material described in this embodiment can be a nickel-based alloy or stainless steel with good low-temperature elasticity and strength, and the non-metallic material can be polyimide with a thermal expansion coefficient similar to that of the metallic material. The wear-resistant layer material can be modified polytetrafluoroethylene with low friction and high sealing performance. However, the present invention is not limited to the above-mentioned types. Those skilled in the art can select the corresponding materials according to specific needs, but all should be carried out in the subsequent preparation process according to the steps described in the present invention. The calcination temperature and tempering process temperature can be set according to different materials and are applicable to any existing technology, which will not be elaborated here.

[0123] In this embodiment, the composite sealing ring prepared by the above molding method is an annular sealing structure installed on the valve seat, which together with the sealing structure on the outer periphery of the valve plate forms a sealing pair.

[0124] Please see Figure 5 and Figure 6 It is a structural schematic diagram of the composite sealing ring of the present invention applicable to extreme temperature alternating conditions and a cross-sectional schematic diagram of the composite sealing ring of the present invention applicable to extreme temperature alternating conditions, including:

[0125] 1. Circular metal support frame;

[0126] Several transition layers 2 are disposed inside the annular metal support frame 1;

[0127] A wear-resistant layer 3 is disposed inside the transition layer 2;

[0128] The elastic compensation device 4 is located on the outside of the annular metal support frame 1 and is used to provide preload through its own elastic energy storage.

[0129] Specifically, the annular metal support frame 1 is located on the outermost side of the composite sealing ring (farthest from the center) to continuously provide radial rebound;

[0130] The wear-resistant layer 3 is located on the innermost side of the composite sealing ring and is used to abut against the valve plate to form a sealing pair.

[0131] The transition layer 2 is located between the annular metal support frame 1 and the wear-resistant layer 3, so as to achieve a linear transition in the coefficient of expansion from the annular metal support frame 1 made of metal material to the wear-resistant layer 3 made of polymer material.

[0132] The elastic compensation device 4 is located on the outside of the annular metal support frame 1 and is used to provide preload through its own elastic energy storage.

[0133] In this embodiment, the elastic compensation device 4 can be a wave spring, which is located on the outermost ring of the composite sealing ring, that is, between the composite sealing ring and the valve seat, continuously and actively providing elastic compensation for the sealing ring, which can reduce the risk of leakage when the sealing pair is worn.

[0134] Understandable, Figure 5 The diagram illustrates the characteristics of each layer in this embodiment using perfect circles. However, in practice, the cross-section of the wear-resistant layer 3 in the triple eccentric butterfly valve is not a perfect circle but an ellipse. Figure 5 This is for illustrative purposes only.

[0135] The technical solution of the present invention has been described above with reference to the preferred embodiments shown in the accompanying drawings. However, it will be readily understood by those skilled in the art that the scope of protection of the present invention is obviously not limited to these specific embodiments. Without departing from the principles of the present invention, those skilled in the art can make equivalent changes or substitutions to the relevant technical features, and the technical solutions after these changes or substitutions will all fall within the scope of protection of the present invention.

Claims

1. A method of forming a composite seal ring suitable for use in extreme temperature alternating service, characterized by, include: Step S1: Obtain deformation data and stress distribution data of the metal support skeleton material and non-metallic material of the composite sealing ring under the target extreme temperature conditions, respectively. Step S2: Determine the layer thickness ratio of the sealing ring based on the deformation data of the metal support skeleton material and the deformation data of the non-metallic material; Step S3: Determine the structural dimensions of the annular metal support frame based on the layer thickness ratio and the standard thickness of the sealing ring to fabricate the annular metal support frame; Step S4: After pre-treating the annular metal support frame, place it in a pre-pressing mold, mix the metal powder and non-metal powder in the corresponding proportion to obtain a transition layer, and lay it on the inner side of the outer ring of the metal support frame in a gradient laying manner. Step S5: The mixed wear-resistant layer powder is laid on the inner side of the transition layer to form a pre-compressed part; Step S6: The pre-pressed parts in the pre-pressing mold are sequentially pressed and sintered in one piece to obtain sintered parts; Step S7: Determine forging parameters based on the pressing parameters, pressing dimensions, and sintering dimensions corresponding to the sintered part, so as to perform radial forging treatment on the sintered part to form a composite sealing ring; Step S8: The fabricated composite sealing ring is subjected to immersion cryogenic treatment and wear resistance testing in sequence, and the test data of the composite sealing ring is obtained to correct the pressing parameters and obtain the composite molded part. Alternatively, the layer thickness ratio in step S2 can be adjusted to re-prepare the composite molded part.

2. A method of forming a composite seal ring suitable for extreme temperature alternating service according to claim 1, wherein, The layer thickness ratio is determined based on the ratio of the maximum deformation of the metal support skeleton material to the average deformation of the non-metallic material, and the number of transition layers is determined based on the layer thickness ratio and the thickness of the metal skeleton of the composite molded part.

3. The method for forming a composite sealing ring suitable for extreme temperature alternation conditions according to claim 2, characterized in that, Step S3 includes: Step S31: Determine the standard wall thickness of the annular metal support frame according to the layer thickness ratio and the standard thickness of the sealing ring, so as to process the metal blank of the metal support frame material into an annular metal support frame with a C-shaped cross section. Step S32, heat treatment is performed on the annular metal support frame, including solution treatment and aging heat treatment; The extension length of the upper and lower end faces of the annular metal support frame is half of the standard wall thickness.

4. The method for forming a composite sealing ring suitable for extreme temperature alternation conditions according to claim 3, characterized in that, In step S4, the number of transition layers is determined based on the layer thickness ratio, so that the transition layer is divided into several layers. The mixing ratio of metal powder and non-metal powder in each layer is determined based on the number of transition layers, and the proportion of metal powder in the transition layer closer to the outer ring of the annular metal support skeleton is higher than that in the transition layer farther from the outer ring of the annular metal support skeleton.

5. The method for forming a composite sealing ring suitable for extreme temperature alternation conditions according to claim 4, characterized in that, Step S7 includes: Step S71: Obtain the pressing size and sintering size to determine the sintering-air ratio based on the pressing size and sintering size; Step S72: Determine the pressing efficiency based on the dimensions before pre-pressing and the dimensions of the pressed part after integrated pressing; Step S73: Determine the additional forging coefficient based on the burn-out ratio and the pressing efficiency, and then determine the forging parameters based on the additional forging coefficient and the preset forging parameters.

6. The method for forming a composite sealing ring suitable for extreme temperature alternating conditions according to claim 5, characterized in that, Step S8 includes: Step S81: Obtain interlayer separation data and leakage data of the composite sealing ring; Step S82: Calculate the cumulative process loss based on the interlayer separation data to determine whether the forging exceeds the limit; Step S83: Calculate the temperature runaway factor based on the leakage data; Step S84: Determine the molding quality of the composite sealing ring based on the accumulated process loss and temperature runaway factor to select the corresponding adjustment strategy.

7. The method for forming a composite sealing ring suitable for extreme temperature alternation conditions according to claim 6, characterized in that, In step S84 If the cumulative process loss is greater than or equal to a preset loss threshold, the forging is deemed to have exceeded the limit. The pressing parameters are then corrected based on the cumulative process loss to obtain the composite molded part. If the cumulative process loss is less than a preset loss threshold and the temperature runaway factor is greater than or equal to a preset temperature control threshold, the layer thickness ratio is determined to be unbalanced, and the layer thickness ratio is adjusted to re-prepare the composite molded part.

8. The method for forming a composite sealing ring suitable for extreme temperature alternation conditions according to claim 7, characterized in that, The pressing parameters include the molding pressure of the integrated pressing, and the correction value of the molding pressure is calculated based on the current molding pressure value and the cumulative process loss.

9. The method for forming a composite sealing ring suitable for extreme temperature alternation conditions according to claim 7, characterized in that, The layer thickness ratio is adjusted to increase the number of transition layers, wherein the temperature runaway factor is positively correlated with the number of transition layers.

10. A composite sealing ring, prepared using the molding method for composite sealing rings suitable for extreme temperature alternation conditions as described in any one of claims 1-9, characterized in that, include: Circular metal support frame; Several transition layers are set inside the annular metal support frame; A wear-resistant layer is set inside the transition layer; An elastic compensation device, located on the outside of the annular metal support frame, is used to provide preload through its own elastic energy storage.

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