Wave-tooth composite gasket

Abstract

The application discloses a wave-tooth composite gasket, which comprises a metal framework, an expanded graphite sealing layer and a metal positioning ring; the side surface of the metal framework is provided with a plurality of wave-tooth grooves, the groove bottom of the wave-tooth groove is provided with a micro-convex bearing pressure edge, the two sides of the metal framework are attached to the expanded graphite sealing layer, and the outer side is covered with the metal positioning ring; the metal framework is formed by stamping 12Cr18Ni9 stainless steel; the preparation method comprises the processes of stamping and slotting, graphite compounding, positioning ring assembling and constant-temperature pressing; the application improves the rebound and sealing pressure capacity through the staggered wave-tooth and micro-convex edge structure, solves the technical problems that the high-temperature graphite layer of the traditional wave-tooth gasket is easy to slip and fall off and the sealing fails under high pressure, can be used for the sealing of petroleum and chemical pipeline flanges, and improves the sealing life by 60%, and has excellent high-temperature stability and anti-creep performance.

Description

Technical Field

[0001] This invention belongs to the field of sealing gasket technology, and specifically relates to a corrugated composite gasket. Background Technology

[0002] Existing traditional corrugated composite gaskets use a single-layer stainless steel metal skeleton with concentric corrugations on the upper and lower surfaces. Sealing is achieved solely through the adhesion of a planar expanded graphite layer to the corrugation surface. Under long-term high-temperature conditions (above 800℃) and high-pressure fluid impact conditions (20MPa), there are core technical defects: the thermal expansion coefficient of the expanded graphite material differs significantly from that of the metal skeleton at high temperatures. The corrugations only have planar contact with the graphite layer, resulting in a non-positional, low-pressure structure. The graphite layer, subjected to high-temperature creep and media erosion, easily slips radially outward along the corrugations and delaminates. After the graphite layer detaches, the metal skeleton directly contacts the flange surface, causing rapid attenuation of the gasket's resilience, insufficient sealing pressure, and rapid media leakage at the pipe flange connection. This significantly increases the frequency of equipment shutdowns and maintenance, and the seal's service life is less than 3000 hours under high-temperature, long-term operating conditions. Existing conventional improvement solutions only thicken the graphite layer and replace it with a high-hardness metal skeleton. They cannot solve the core problem of graphite slippage and detachment at high temperatures from the perspectives of corrugated structure, graphite limiting, and pressure-bearing contact structure. They have limitations in structural improvement and poor high-temperature sealing stability. Summary of the Invention

[0003] To address the technical problems of easy slippage and detachment of the expanded graphite sealing layer and rapid seal failure under high temperature and high pressure in existing traditional corrugated gaskets, this invention provides a corrugated composite gasket. Through the combination of staggered corrugated grooves, continuous micro-convex pressure-bearing ridges at the bottom of the grooves, and inner and outer metal limiting structures, it restricts the radial slippage of the graphite layer at high temperature, improves the interlocking and clamping force between the graphite layer and the metal skeleton, optimizes the gasket's resilience and pressure-bearing performance, and extends the service life of the high-temperature seal.

[0004] To achieve the above objectives, the present invention adopts the following technical solution:

[0005] A corrugated composite gasket includes an annular metal skeleton, an expanded graphite sealing layer, and a metal positioning ring. The metal skeleton is a flat annular stainless steel sheet, and its surface is machined with annular corrugated grooves. Multiple corrugated grooves are arranged radially in sequence, with a groove depth of 0.35 mm for each groove. The bottom of each groove is integrally stamped with continuous micro-convex pressure-bearing ridges, each ridge having a semi-circular cross-section and a protrusion height of 0.08 mm. The expanded graphite sealing layer is adhered to and covers the surface of the metal skeleton, and has a thickness of 0.8 mm. The metal positioning ring is coaxially sleeved on the outer circumference of the metal skeleton, with its inner end face abutting against the outer edge of the expanded graphite sealing layer.

[0006] In a preferred embodiment of the present invention, the metal skeleton is made of 12Cr18Ni9 austenitic stainless steel, the metal skeleton plate is 1.2mm thick, the radial width of the metal skeleton is 25mm, and the radial center distance between two adjacent concentric wave grooves is 1.6mm.

[0007] In a preferred embodiment of the present invention, the expanded graphite sealing layer is an expanded graphite rolled sheet with a graphite carbon content ≥99.5%, and the expanded graphite sealing layer contains 5wt% short-cut aluminum silicate high-temperature resistant fibers with a single fiber length of 0.2mm.

[0008] In a preferred embodiment of the present invention, the micro-convex pressure-bearing ridge is continuously arranged along the annular direction of the corrugated groove, and the radius of the arc of the micro-convex pressure-bearing ridge is 0.04mm.

[0009] In a preferred embodiment of the present invention, the metal positioning ring is made of low carbon steel by stamping, and an annular limiting step is formed in the inner ring of the metal positioning ring, which engages with the outer edge of the expanded graphite sealing layer.

[0010] In a preferred embodiment of the present invention, an annular spacer metal edge is provided on the inner edge of the metal skeleton, the spacer metal edge extends inward by 0.5mm, and the spacer metal edge completely covers the inner end face of the expanded graphite sealing layer.

[0011] A method for preparing a corrugated composite gasket includes the following steps: Step S1, sheet metal stamping: Select a 12Cr18Ni9 stainless steel sheet with a thickness of 1.2mm, use a CNC corrugated die to simultaneously stamp the concentric corrugated grooves on the sheet surface and the slightly convex bearing edge at the bottom of the groove, with a stamping pressure of 120 tons, and remove the burrs from the sheet after stamping to obtain a semi-finished metal skeleton. Step S2, graphite layer bonding pretreatment: Cut the expanded graphite plate containing 5wt% aluminum silicate fiber into ring graphite sheets, preheat the ring graphite sheets to 120℃ and keep them at a constant temperature for 15 minutes to remove internal moisture.

[0012] Step S3, constant temperature composite pressing process: The preheated annular graphite sheets are placed on the sides of the metal skeleton and sent into a flat plate hot press. The hot pressing temperature is 180℃, the hot pressing pressure is 35MPa, and the constant temperature and pressure holding time is 20min to complete the bonding and composite of the expanded graphite sealing layer and the metal skeleton.

[0013] Step S4, positioning ring assembly and shaping process: The stamped low carbon steel metal positioning ring is coaxially sleeved on the outer edge of the composite gasket. A radial clamping force of 10MPa is applied using a radial die to press the inner limiting step of the metal positioning ring against the outer edge of the expanded graphite sealing layer. Finally, the gasket is left to cool at room temperature for 30 minutes, and the excess graphite burrs are trimmed to obtain the finished corrugated composite gasket.

[0014] Compared with the prior art, the present invention has the following beneficial effects: 1. The metal skeleton plate adopts a combination structure of concentric wave grooves and continuous micro-convex pressure-bearing ridges at the bottom of the grooves. Combined with the inner ring spacer metal edge and the outer ring positioning ring for double limiting, the high-temperature radial sliding and falling off of the expanded graphite is restricted from the inner, outer and sandwich triple structure. This solves the technical problem of rapid failure of existing gasket high-temperature seals and increases the seal service life by 60% under continuous working conditions of 850℃.

[0015] 2. The micro-convex bearing ridge increases the frictional force between the graphite and the metal skeleton, stabilizing the compression and rebound performance of the gasket. Under long-term high-pressure conditions, the rebound attenuation rate is reduced by 42%, eliminating the need for frequent secondary tightening of flange bolts.

[0016] 3. High-temperature resistant aluminum silicate fibers are added to the graphite layer to enhance the graphite's resistance to creep and erosion, ensuring that the medium fluid does not delaminate or break down even after long-term erosion.

[0017] 4. The supporting preparation method adopts a synchronous stamping and constant temperature hot pressing integrated process. The parameters of each process are matched with the special corrugated tooth structure of this invention. The yield rate of industrial production is ≥98%, and the production cost is controllable.

[0018] 5. The gasket is applicable to a wide temperature range from cryogenic to ultra-high temperature conditions, has a wide pressure range, and is suitable for pipeline flange sealing in multiple industries such as petrochemical, power, and metallurgy, with strong versatility. Attached Figure Description

[0019] To more clearly illustrate the technical solutions in the embodiments or prior art, the drawings used in the description of the embodiments or prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0020] Figure 1 This is a schematic diagram of the structure of a corrugated composite gasket provided in an embodiment of the present invention.

[0021] Figure 2 This is a partial enlarged view of the corrugated groove and the micro-convex pressure-bearing ridge provided in an embodiment of the present invention.

[0022] Figure 3 This is a flowchart illustrating a method for preparing a corrugated composite gasket according to an embodiment of the present invention. Detailed Implementation

[0023] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are within the scope of protection of this application.

[0024] like Figure 1 and Figure 2 As shown, this embodiment of the invention provides a corrugated composite gasket, comprising an annular metal skeleton 1, an expanded graphite sealing layer 2, and a metal positioning ring 3. The metal skeleton 1 is a flat annular stainless steel sheet, and the surface of the metal skeleton 1 is machined with annular corrugated grooves 11. Multiple corrugated grooves 11 are arranged radially in sequence, and the groove depth of a single corrugated groove 11 is 0.35 mm. The bottom of the corrugated groove 11 is integrally stamped with continuous micro-convex pressure-bearing ridges 12. The cross-section of the micro-convex pressure-bearing ridges 12 is semi-circular, and the protrusion height of the micro-convex pressure-bearing ridges 12 is 0.08 mm. The semi-circular micro-convex ridges increase the contact points and friction between the graphite and the metal skeleton 1. During high-temperature creep, the micro-convex ridges are embedded inside the graphite layer, further locking the displacement of the graphite layer and solving the core problem of high-temperature slippage and detachment.

[0025] The expanded graphite sealing layer 2 is attached to the plate surface covering the metal skeleton 1, and the thickness of the expanded graphite sealing layer 2 is 0.8mm; the metal positioning ring 3 is coaxially sleeved on the outer circumference of the metal skeleton 1, and the inner end face of the metal positioning ring 3 is tightly attached to the outer edge of the expanded graphite sealing layer 2.

[0026] The metal frame 1 is made of 12Cr18Ni9 austenitic stainless steel. The thickness of the metal frame 1 plate is 1.2mm, and the radial width of the metal frame 1 is 25mm. The radial center distance between two adjacent concentric wave grooves 11 is 1.6mm.

[0027] The expanded graphite sealing layer 2 is a rolled expanded graphite sheet with a carbon content ≥99.5%. The expanded graphite sealing layer 2 contains 5wt% short-cut aluminosilicate high-temperature resistant fibers, each fiber being 0.2mm in length. These aluminosilicate fibers are heat-resistant and do not soften, forming a mesh-like support skeleton within the graphite layer. This reduces high-temperature creep of the graphite, enhances the structural strength of the graphite layer itself, and reduces the probability of delamination and cracking.

[0028] The micro-convex pressure-bearing ridge 12 is continuously arranged along the annular direction of the corrugated groove 11, and the radius of the arc of the micro-convex pressure-bearing ridge 12 is 0.04mm. The arc transition structure of the micro-convex pressure-bearing ridge is defined, and the absence of sharp corners avoids high-temperature stress concentration from piercing the graphite layer, thus ensuring long-term sealing integrity.

[0029] The metal positioning ring 3 is made of low-carbon steel by stamping. The inner ring of the metal positioning ring 3 has an annular limiting step 31, which engages with the outer edge of the expanded graphite sealing layer 2. The metal positioning ring 3 presses against the outer edge of the graphite through the limiting step 31, forming a radial limiting barrier from the outer ring of the gasket, blocking the outward sliding path of the graphite. The low-carbon steel positioning ring is low in cost, easy to stamp and form, and its thickness is consistent with the skeleton to ensure a smooth flange fit.

[0030] The inner edge of the metal skeleton 1 is provided with an annular metal strip 13, which extends inward by 0.5mm and completely covers the inner end face of the expanded graphite sealing layer 2.

[0031] The corrugated composite gasket has an overall compression resilience coefficient m=4.25, a minimum pre-tightening sealing pressure y=50MPa, a working pressure range of 0.6~26.0MPa, and a continuous operating temperature range of -250℃~+850℃.

[0032] like Figure 3 As shown, the present invention also provides a method for preparing a corrugated composite gasket, comprising the following steps: Step S1, sheet metal stamping: Select a 12Cr18Ni9 stainless steel sheet with a thickness of 1.2mm, and use a CNC corrugated tooth die to simultaneously stamp the concentric corrugated tooth groove 11 on the sheet surface and the slightly convex bearing edge 12 at the bottom of the groove. The stamping pressure is 120 tons. After stamping, remove the burrs from the sheet to obtain the semi-finished metal skeleton 1. Step S2, graphite layer bonding pretreatment: Cut the expanded graphite plate containing 5wt% aluminum silicate fiber into ring graphite sheets, preheat the ring graphite sheets to 120℃ and keep them at a constant temperature for 15 minutes to remove internal moisture.

[0033] Step S3, constant temperature composite pressing process: The preheated annular graphite sheets are placed on the sides of the metal skeleton 1 and sent into a flat hot press. The hot pressing temperature is 180℃, the hot pressing pressure is 35MPa, and the constant temperature and pressure holding time is 20min to complete the bonding and composite of the expanded graphite sealing layer 2 and the metal skeleton 1.

[0034] Step S4, positioning ring assembly and shaping process: The stamped low carbon steel metal positioning ring 3 is coaxially sleeved on the outer edge of the composite gasket. A radial clamping force of 10MPa is applied by a radial die to make the inner limiting step 31 of the metal positioning ring 3 press against the outer edge of the expanded graphite sealing layer 2. Finally, it is left to cool at room temperature for 30 minutes and the excess graphite burrs are trimmed to obtain the finished corrugated composite gasket.

[0035] The above four processes—stamping, pretreatment, hot pressing, and assembly shaping—are designed with parameters specific to the unique structure of this invention: Step S1, CNC synchronous stamping: synchronously forming the upper and lower staggered corrugated grooves and the micro-convex ridges at the bottom of the grooves. A stamping pressure of 120 tons ensures that the micro-convex ridges are integrally formed without breakage, avoiding secondary processing that could damage the overall strength of the metal skeleton; Step S2, graphite preheating: maintaining a temperature of 120℃ to remove the internal crystal water of the graphite sheet, preventing the expansion of water vapor during hot pressing and causing blistering and delamination of the graphite layer; Step S3, constant temperature hot pressing: holding pressure at 180℃, 35MPa, and 20min causes slight plastic deformation of the graphite material, tightly wrapping the corrugated grooves and the micro-convex bearing ridges. The graphite embeds into the gaps of the corrugated grooves, forming a mechanical interlock, significantly improving the bonding force between the graphite and the metal skeleton; Step S4, radial clamping assembly of the positioning ring: 10MPa. Radial pressure causes the positioning ring step to completely lock the outer edge of the graphite. After cooling and shaping, the rebound and outward expansion stress of the graphite layer is eliminated, and the graphite layer of the finished gasket has no risk of warping or slippage.

[0036] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely preferred examples and are not intended to limit the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of the present invention is defined by the appended claims and their equivalents.

Claims

1. A corrugated composite gasket, characterized in that, The system includes an annular metal skeleton (1), an expanded graphite sealing layer (2), and a metal positioning ring (3). The metal skeleton (1) is a flat annular stainless steel sheet. The surface of the metal skeleton (1) is machined with annular corrugated grooves (11). Multiple corrugated grooves (11) are arranged radially in sequence. The groove depth of a single corrugated groove (11) is 0.35 mm. The bottom of the corrugated groove (11) is integrally stamped with a continuous micro-convex pressure-bearing ridge (12). The cross-section of the micro-convex pressure-bearing ridge (12) is semi-circular, and the protrusion height of the micro-convex pressure-bearing ridge (12) is 0.08 mm. The expanded graphite sealing layer (2) is attached to and covers the surface of the metal skeleton (1). The thickness of the expanded graphite sealing layer (2) is 0.8 mm. The metal positioning ring (3) is coaxially sleeved on the outer circumference of the metal skeleton (1). The inner end face of the metal positioning ring (3) is tightly abutted against the outer edge of the expanded graphite sealing layer (2).

2. The corrugated composite gasket according to claim 1, characterized in that, The metal skeleton (1) is made of 12Cr18Ni9 austenitic stainless steel. The metal skeleton (1) has a plate thickness of 1.2mm and a radial width of 25mm. The radial center distance between two adjacent concentric wave grooves (11) is 1.6mm.

3. The corrugated composite gasket according to claim 1, characterized in that, The expanded graphite sealing layer (2) is an expanded graphite rolled plate with a graphite carbon content ≥99.5%. The expanded graphite sealing layer (2) contains 5wt% short-cut aluminum silicate high-temperature resistant fibers with a single fiber length of 0.2mm.

4. The corrugated composite gasket according to claim 1, characterized in that, The micro-convex pressure-bearing ridge (12) is continuously arranged along the annular direction of the corrugated groove (11), and the radius of the arc of the micro-convex pressure-bearing ridge (12) is 0.04mm.

5. The corrugated composite gasket according to claim 1, characterized in that, The metal positioning ring (3) is made of low carbon steel by stamping. The inner ring of the metal positioning ring (3) has an annular limiting step (31), which engages with the outer edge of the expanded graphite sealing layer (2).

6. The corrugated composite gasket according to claim 1, characterized in that, The inner edge of the metal skeleton (1) is provided with an annular spacer metal edge (13), the spacer metal edge (13) extends inward by 0.5mm, and the spacer metal edge (13) completely covers the inner end face of the expanded graphite sealing layer (2).

7. A method for preparing the corrugated composite gasket according to any one of claims 1 to 6, characterized in that, Includes the following steps: Step S1, sheet metal stamping: Select a 12Cr18Ni9 stainless steel sheet with a thickness of 1.2mm, and use a CNC corrugated tooth mold to simultaneously stamp the concentric corrugated tooth groove (11) on the sheet surface and the slightly convex bearing edge (12) at the bottom of the groove. The stamping pressure is 120 tons. After stamping, remove the burrs from the sheet to obtain the metal skeleton (1) semi-finished product. Step S2, graphite layer bonding pretreatment: Cut the expanded graphite plate containing 5wt% aluminum silicate fiber into ring graphite sheets, preheat the ring graphite sheets to 120℃ and keep them at a constant temperature for 15 minutes to remove internal moisture. Step S3, constant temperature composite pressing process: The preheated annular graphite sheets are placed on the side of the metal skeleton (1) and sent into the flat hot press. The hot pressing temperature is 180℃, the hot pressing pressure is 35MPa, and the constant temperature and pressure holding time is 20min to complete the bonding and composite of the expanded graphite sealing layer (2) and the metal skeleton (1). Step S4, positioning ring assembly and shaping process: The stamped low carbon steel metal positioning ring (3) is coaxially sleeved on the outer edge of the composite gasket. A radial clamping force of 10MPa is applied by a radial die to make the inner limiting step (31) of the metal positioning ring (3) press against the outer edge of the expanded graphite sealing layer (2). Finally, it is left to cool at room temperature for 30 minutes and the excess graphite burrs are cut off to obtain the finished corrugated composite gasket.

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