Main shaft rotation rubber active pressure water sealing device of water turbine

Abstract

The invention discloses a water turbine main shaft rotating rubber active pressure water sealing device which comprises a rotating metal ring, a metal annular sealing seat and a rubber sealing ring, and the rotating metal ring is coaxial with a main shaft and detachably and fixedly connected with the main shaft; the rotary metal ring and the metal annular sealing seat are oppositely arranged; a sealing seat ring groove is formed in one side, facing the rotating metal ring, of the metal ring-shaped sealing seat; the upper end of the rubber sealing ring is fixedly connected with the lower side of the rotating metal ring, and the lower part is arranged in the sealing seat ring groove; the lower end of the rubber sealing ring is provided with a rubber sealing ring groove and an inner rotary sealing working ring belt and an outer rotary sealing working ring belt which are symmetrically arranged on the two sides of the rubber sealing ring groove. And the inner and outer rotary sealing working ring belts are respectively attached to the inner and outer ring surfaces of the sealing seat ring groove under water pressure and are in rotary movable fit with the inner and outer ring surfaces during working. The device has the advantages of being simple in structure, safe and reliable, guaranteeing the sealing effect, and being capable of meeting a remote monitoring management mode of few-person or unattended maintenance and long-term safe operation.

Description

Technical Field

[0001] This invention relates to the field of working seals for turbine main shafts, and more specifically to a rotary rubber active pressure water seal device for turbine main shafts. Background Technology

[0002] The piston-type rubber end face seal for the main shaft of a hydro turbine is a widely used working seal for hydro turbines. This seal structure mainly consists of three parts: a rotating metal ring (disc-shaped rotating metal ring), an annular rubber sealing ring, and a metal annular sealing seat with an annular groove structure and water tank function.

[0003] like Figure 1 The diagram shows the existing technology of piston-type rubber end-face seal structure and working mode of a turbine main shaft. In the diagram: 1—the main shaft of the turbine; 2—a split (combined) rotating metal ring installed on the main shaft 1; 3—a detachable stainless steel annular anti-wear plate installed under the rotating metal ring disc; 4—a rubber sealing ring installed in the sealing seat groove of the metal annular seal seat and capable of axial upward and downward movement only, not rotation; 5—a metal annular seal seat with an annular groove structure and an active pressure water inlet structure, which forms a closed water tank function after the annular rubber sealing ring is installed; 501—several limit pins arranged and installed on the metal annular seal seat 5 to cooperate with the corresponding limit pin holes of the rubber sealing ring 4, thereby limiting and preventing the rotation of 4. The metal annular seal seat 5 is provided with a sealing seat water supply hole 52 that connects to the sealing seat annular groove 51.

[0004] During operation, the rubber sealing ring 4 of the piston-type rubber end face seal of the turbine main shaft rises under the action of the pressure water 6 in the sealing seat annular groove 51 of the metal annular sealing seat 5 and moves to the place where it mates with the working plane (end face) of the stainless steel annular anti-wear plate 3 of the rotating metal ring 2, thereby forming a dynamic sealing relationship of the end face and sealing against the leakage water 7. The existing technology of piston-type rubber end face seals for turbine main shafts uses nitrile rubber (NBR) and other rubber materials as dynamic sealing materials. Since rubber materials are flexible materials with high friction coefficient, high elasticity, low hardness and non-thermal conductivity, they are prone to burn-out accidents if contact friction occurs during operation and cooling and lubrication are inadequate. Therefore, this type of seal requires sufficient water cooling and lubrication.

[0005] The existing technology for piston-type rubber end face seals of turbine main shafts addresses the dynamic sealing fit between the rubber sealing ring end face and the rotating metal ring by creating several axial pressure water supply holes on the rubber sealing ring (ring) to inject pressurized water into the ring groove on the working end face of the rubber sealing ring and supply water to the inner and outer end faces of its dynamic sealing fit.

[0006] like Figure 1As shown, in actual use, the high friction of the rubber sealing ring 4 often causes continuous wear between the upper end face of the rubber sealing ring 4 and the lower end face of the stainless steel annular anti-wear plate 3. This results in the rubber sealing ring 4 suddenly darting like a spring when adjusting its position up and down, posing a risk of excessive movement. When this happens, because the rubber sealing ring 4 is too close to the rotating stainless steel annular anti-wear plate 3 of the rotating metal ring 2, the cooling lubricating water between the sealing surfaces is squeezed out. This causes the rubber sealing ring 4, made of nitrile rubber with low heat resistance, to burn out due to high frictional heat after direct contact and friction with the annular anti-wear plate 3.

[0007] Because rubber seals essentially utilize the high elasticity, easy deformation, and good wear resistance of rubber materials, while also exhibiting significant dimensional instability, the more complex their structure and the more functions they perform, the more difficult it is to calculate and control their operating state. This makes such seals inherently susceptible to burn-out accidents due to fluctuations in operating parameters during operation.

[0008] The aforementioned situation makes it difficult to achieve automatic control and information management of the existing piston-type rubber end face seals for turbine main shafts, forcing the adoption of a management model centered on experience-based, manual intervention. However, this unpredictable management model, requiring constant on-call support, fails to address the root cause of the problem and consumes significant maintenance resources. Summary of the Invention

[0009] The purpose of this invention is to address the shortcomings of existing technologies by providing a simple, safe, reliable, and effective sealing device for the rotating rubber active pressure water seal of a turbine main shaft that can meet the requirements of remote monitoring and management with minimal or no human intervention and long-term safe operation.

[0010] The technical objective of this invention is achieved through the following technical solution: A rotary rubber active pressure water seal device for a turbine main shaft includes a rotating metal ring, a metal annular sealing seat, and a rubber sealing ring. The rotating metal ring is coaxial with the main shaft and detachably fixedly connected to it. The rotating metal ring and the metal annular sealing seat are arranged opposite to each other. The metal annular sealing seat has a sealing seat groove on the side facing the rotating metal ring. The upper end of the rubber sealing ring is fixedly connected to the lower side of the rotating metal ring, and its lower part is disposed in the sealing seat groove. The base part of the rubber sealing ring that does not participate in the contact and rotational sealing operation with the inner and outer annular surfaces of the sealing seat groove has a cross-sectional width smaller than the width of the rectangular cross-sectional groove of the sealing seat, and does not contact the sealing seat groove at all during sealing operation. The lower end of the rubber sealing ring has a rubber sealing ring groove and an inner rotary sealing working ring band and an outer rotary sealing working ring band symmetrically arranged on both sides of the rubber sealing ring groove. The inner rotary sealing working ring band and the outer rotary sealing working ring band respectively contact the inner and outer annular surfaces of the sealing seat groove under water pressure and rotate during operation.

[0011] Preferably, the height of the inner and outer rotary sealing working rings is less than 30 mm.

[0012] Preferably, the lower side of the rotating metal ring is provided with a positioning groove that mates with the upper end of the rubber sealing ring.

[0013] Preferably, an aluminum alloy outer ring and an aluminum alloy inner ring are connected to the lower side of the rotating metal ring; the positioning groove is formed between the aluminum alloy outer ring and the aluminum alloy inner ring at intervals.

[0014] Preferably, the rotating metal ring is detachably connected to the aluminum alloy outer ring and the aluminum alloy inner ring.

[0015] Preferably, the outer and inner ring surfaces of the sealing seat groove are provided with a wear-resistant coating material to reduce wear.

[0016] Preferably, the inner and outer rotary sealing working rings are respectively provided with a plurality of radial pressure lubricating water holes and radial self-lubricating holes communicating with the sealing seat ring groove on the circumference, and self-lubricating graphite columns are provided in the radial self-lubricating holes.

[0017] Preferably, the upper end face of the rotating metal ring has a plurality of screw holes evenly distributed circumferentially, the screw holes penetrating the upper end face and the lower end face of the rotating metal ring; a connecting bolt is provided in the screw holes, and the upper end face of the rubber sealing ring is provided with a connecting screw hole for cooperating with the connecting bolt, and the rotating metal ring and the rubber sealing ring are bolted together.

[0018] Compared with the prior art, the beneficial effects of the present invention are: 1. This invention changes the sealing relationship between the dynamic and static end faces of the rubber sealing ring relative to the rotating metal ring in the existing technology of piston-type rubber end face seals for turbine main shafts. This avoids the problem of continuous wear between the upper end face of the rubber sealing ring and the lower end face of the stainless steel annular anti-wear plate, which causes the rubber sealing ring to suddenly jerk like a spring when adjusting its position up and down. Furthermore, it avoids the problem of the rubber sealing ring burning out due to high heat from direct contact and friction with the stainless steel annular anti-wear plate. This technical measure features a simple structure, high safety and reliability, guaranteed sealing effect, and can meet the requirements of remote monitoring and management modes with minimal or no personnel and long-term safe operation.

[0019] 2. The inner and outer rotating sealing working rings of this invention are respectively provided with multiple radial pressure lubrication water holes and multiple self-lubricating graphite pillars on their circumference, communicating with the sealing seat ring groove. This technical measure ensures that the inner and outer ring surfaces of the inner and outer rotating sealing working rings and the sealing seat ring groove receive sufficient adhesion, lubrication, and protection of graphite molecules, forming a good non-contact sealing shape and reducing the coefficient of friction and wear. Attached Figure Description

[0020] Figure 1 This is a structural diagram of existing technology; Figure 2 This is a schematic diagram of the structure of the present invention; Figure 3 yes Figure 2 A schematic diagram of the structure of the rotating metal ring, the inner aluminum alloy ring, and the outer aluminum alloy ring; Figure 4 yes Figure 2 Schematic diagram of the structure of the rubber sealing ring and screw; Figure 5 yes Figure 4 Diagram of the AA direction; Figure 6 yes Figure 4 Diagram of the middle BB direction; Figure 7 yes Figure 2 Top view of the rotating metal ring; Reference numerals: 1—Main axis; 2—Rotating metal ring; 21—Screw hole; 22—Nut hole; 23—Screw; 3—Stainless steel annular wear-resistant plate; 31—Inner ring of aluminum alloy; 32—Outer ring of aluminum alloy; 301—Positioning groove; 4—Rubber sealing ring; 41—Rubber sealing ring groove; 401—Inner rotary seal working ring; 402—Outer rotary seal working ring; 403—Radial pressure lubrication water hole; 404—Radial self-lubricating hole; 5—Metal annular sealing seat; 51—Sealing seat annular groove; 52—Sealing seat water supply hole; 501—Limit pin; 6—Active pressurized water; 7—Leaking water; 8—Screw assembly; 81—Screw; 82—Nut; 83—Washer. Detailed Implementation

[0021] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0022] Therefore, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention.

[0023] It should be noted that similar reference numerals and letters in the following figures indicate similar items; therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures. Furthermore, the terms "first," "second," etc., are used only to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0024] like Figure 1 — Figure 7 As shown, a rotary rubber active pressure water seal device for a turbine main shaft includes a rotating metal ring 2, a metal annular sealing seat 5, and a rubber sealing ring 4. The rotating metal ring 2 is coaxial with the main shaft 1 and is detachably fixedly connected to the main shaft 1. The rotating metal ring 2 and the metal annular sealing seat 5 are arranged opposite to each other. The metal annular sealing seat 5 has a sealing seat groove 51 on the side facing the rotating metal ring 2. The upper end of the rubber sealing ring 4 is fixedly connected to the lower side of the rotating metal ring 2, and its lower part is disposed in the sealing seat groove 51. The rubber sealing ring 4 does not participate in the inner and outer rings of the sealing seat groove 51. The base part that fits and rotates to seal has a axial cross-section width smaller than the width of the rectangular cross-section annular groove of the sealing seat, and does not fit with the sealing seat annular groove 51 at all during sealing. The lower end of the rubber sealing ring 4 is provided with a rubber sealing ring groove 41 and an inner rotating sealing working ring 401 and an outer rotating sealing working ring 402 symmetrically arranged on both sides of the rubber sealing ring groove 41. The inner rotating sealing working ring 401 and the outer rotating sealing working ring 402 fit with the inner and outer annular surfaces of the sealing seat annular groove 51 respectively under water pressure and rotate during operation.

[0025] During operation, the turbine's main shaft 1 drives the rotating metal ring 2 and the rubber sealing ring 4 fixed to the lower side of the rotating metal ring 2 to rotate together. The inner rotating sealing working ring 401 and the outer rotating sealing working ring 402 at the lower end of the rubber sealing ring 4 respectively adhere to the inner and outer ring surfaces of the sealing seat groove 51 under water pressure and rotate dynamically during operation. This technical measure changes the existing piston-type rubber end face seal of the turbine main shaft 1, which involves a dynamic and static end face sealing relationship between the rubber sealing ring 4 and the rotating metal ring 2. This avoids the continuous wear between the upper end face of the rubber sealing ring 4 and the lower end face of the stainless steel annular anti-wear plate 3, preventing the rubber sealing ring 4 from suddenly shifting like a spring when adjusting its position. It also avoids the problem of the rubber sealing ring 4 burning out due to high heat from direct contact friction with the stainless steel annular anti-wear plate 3. This technical measure features a simple structure, safety and reliability, guaranteed sealing effect, and can meet the requirements of remote monitoring and management modes with minimal or no personnel, as well as long-term safe operation.

[0026] like Figure 2 — Figure 7 As shown, the lower side of the rotating metal ring 2 has a positioning groove 301 that mates with the upper end of the rubber sealing ring 4. In actual use, the lower side of the rotating metal ring 2 is connected to an aluminum alloy outer ring 32 and an aluminum alloy inner ring 31; the positioning groove 301 is formed between the aluminum alloy outer ring 32 and the aluminum alloy inner ring 31 at intervals. The aluminum alloy outer ring 32 and the aluminum alloy inner ring 31 can be made of high-strength aerospace aluminum alloy. The rubber sealing ring 4 can be made of rubber material with a hardness not exceeding Shore A 80. The aluminum alloy inner and outer rings form an annular positioning groove 301, facilitating quick positioning when installing the rubber sealing ring 4, thereby improving installation efficiency. This technical measure has the advantages of simple structure and improved installation efficiency. At the same time, using the lower specific gravity of the aluminum alloy inner and outer rings reduces weight; when installed on the lower side of the rotating metal ring 2, it effectively reduces the total weight of the inner and outer rings; this technical measure is beneficial for on-site installation work.

[0027] like Figure 2 , Figure 3 , Figure 7As shown, the rotating metal ring 2 is detachably connected to the aluminum alloy outer ring 32 and the aluminum alloy inner ring 31. In actual use, the aluminum alloy outer ring 32 and the aluminum alloy inner ring 31 can be welded or bonded to the lower side of the rotating metal ring 2. However, a fixed connection would be inconvenient for replacing the aluminum alloy outer ring 32 and the aluminum alloy inner ring 31. Therefore, the rotating metal ring 2 is detachably connected to the aluminum alloy outer ring 32 and the aluminum alloy inner ring 31. Common detachable connection structures include screw connections and bolt connections. For example, the upper end face of the rotating metal ring 2 has through holes evenly distributed circumferentially, penetrating both its upper and lower ends. The upper end faces of the aluminum alloy outer ring 32 and the aluminum alloy inner ring 31 have screw holes corresponding to the positions of the through holes, and the rotating metal ring 2 is connected to the aluminum alloy outer ring 32 and the aluminum alloy inner ring 31 by screws 23. This technical measure facilitates the replacement of the aluminum alloy outer ring 32 and the aluminum alloy inner ring 31.

[0028] like Figure 2 As shown, the upper end of the rubber sealing ring 4 is fixedly connected to the lower side of the rotating metal ring 2, and its lower part is disposed within the sealing seat groove 51. Specifically, the rubber sealing ring 4 includes an upper base portion and a lower inner rotating sealing working ring band 401 and an outer rotating sealing working ring band 402. The lower end of the rubber sealing ring 4 is provided with a rubber sealing ring groove 41. The inner rotating sealing working ring band 401 and the outer rotating sealing working ring band 402 are symmetrically arranged on both sides of the rubber sealing ring groove 41. In actual use, the height of the inner rotating sealing working ring band 401 and the outer rotating sealing working ring band 402 is less than 30mm.

[0029] The diameters of the inner and outer annular surfaces of the rubber sealing ring 4 base portion are smaller than the diameters of the inner and outer annular surfaces of the sealing seat annular groove 51, meaning the cross-sectional width of the rubber sealing ring 4 base portion is smaller than the cross-sectional width of the sealing seat annular groove 51. During operation, the base portion of the rubber sealing ring 4 does not contact the inner and outer annular surfaces of the sealing seat annular groove 51. The inner rotating sealing working ring 401 and outer rotating sealing working ring 402 at the bottom of the rubber sealing ring 4 respectively mate with the inner and outer annular surfaces of the sealing seat annular groove 51. Specifically, the base portion of the rubber sealing ring 4 that does not participate in contacting and rotating with the inner and outer annular surfaces of the sealing seat annular groove 51 during sealing has a axial cross-sectional width smaller than the width of the rectangular annular groove of the sealing seat, and does not contact the sealing seat annular groove 51 at all during sealing operation. The inner rotating sealing working ring 401 and outer rotating sealing working ring 402 respectively contact the inner and outer annular surfaces of the sealing seat annular groove 51 under water pressure and rotate during operation.

[0030] like Figure 2 — Figure 6As shown, the inner rotary seal working ring 401 and the outer rotary seal working ring 402 are respectively provided with multiple radial pressure lubrication water holes 403 and multiple self-lubricating graphite columns on their circumference, which communicate with the sealing seat ring groove 51. In actual use, the inner rotary seal working ring 401 and the outer rotary seal working ring 402 are respectively provided with multiple radial pressure lubrication water holes 403 and radial self-lubricating holes 404 on their circumference, which communicate with the sealing seat ring groove 51, and self-lubricating graphite columns are set in the radial self-lubricating holes 404. In actual use, Self-lubricating graphite columns are made of self-lubricating materials containing carbon fibers. Types of self-lubricating graphite columns include carbon fiber graphite columns and carbon fiber self-lubricating graphite columns. Because carbon fiber materials possess high strength and excellent solid lubrication properties, they are more effective than general solid lubricating materials in ensuring the reliable and long-term safe operation of machinery with friction pairs, such as solid self-lubricating bearings and seals.

[0031] During operation, the inner and outer rotating sealing rings 401 and 402 come into contact with the inner and outer ring surfaces of the sealing seat groove 51 under water pressure and rotate during operation. This causes friction between the inner and outer rotating sealing rings 401 and 402 and the inner and outer ring surfaces of the sealing seat groove 51. Multiple radial pressure lubrication water holes 403 and multiple self-lubricating graphite columns, communicating with the sealing seat groove 51, are provided on the inner and outer rotating sealing rings 401 and 402 respectively. This technical measure ensures sufficient graphite molecule adhesion, lubrication, and protection for the inner and outer ring surfaces of the inner and outer rotating sealing rings 401 and 402 and the sealing seat groove 51, forming a good non-contact seal and reducing the coefficient of friction and wear.

[0032] In practical use, the rotating metal ring 2 and the rubber sealing ring 4 can be fixedly connected by means of adhesive bonding or other methods. In this embodiment, the rotating metal ring 2 and the rubber sealing ring 4 have a detachable connection structure.

[0033] Specifically, the upper end face of the rotating metal ring 2 has multiple threaded holes evenly distributed circumferentially, which penetrate the upper and lower end faces of the rotating metal ring 2; connecting bolts are provided in the threaded holes, and the upper end face of the rubber sealing ring 4 has connecting threaded holes for mating with the connecting bolts, and the rotating metal ring 2 and the rubber sealing ring 4 are bolted together. Figure 2As shown, in actual use, the rotating metal ring 2 and the rubber sealing ring 4 can also be connected by a screw assembly 8, which includes a screw 81, a nut 82, and a washer 83. Multiple screw holes 21 and nut holes 22 are evenly distributed circumferentially on the upper end face of the rotating metal ring 2. The lower part of the screw 81 is threadedly connected to the connecting screw hole on the upper end face of the rubber sealing ring 4, and the upper part of the screw 81 is connected to the nut 82. The washer 83 is disposed in the nut hole 22. After the nut 82 is inserted into the nut hole 22 and tightened, the lower end of the nut 82 abuts against the upper end of the washer 83. This technical measure facilitates the replacement of the rubber sealing ring 4.

[0034] The outer and inner ring surfaces of the sealing seat annular groove 51 are coated with a wear-resistant coating material to reduce wear. In actual use, the rotating metal ring 2 and the metal annular sealing seat 5 are arranged vertically opposite each other. The sealing seat is a metal annular sealing seat 5 made of metal material, and the metal annular sealing seat 5 has a sealing seat annular groove 51 on the side facing the rotating metal ring 2; the inner and outer ring surfaces of the sealing seat annular groove 51 of the metal annular sealing seat 5 are also made of metal. The wear-resistant coating material on the outer and inner ring surfaces of the sealing seat annular groove 51 can improve the service life of the sealing seat annular groove 51. The wear-resistant coating material can be thermally sprayed high-hardness tungsten carbide wear-resistant alloy, thermally sprayed Teflon polymer friction-reducing material, etc.

[0035] The technical solutions provided by the embodiments of the present invention have been described in detail above. Specific examples have been used to illustrate the principles and implementation methods of the embodiments of the present invention. The descriptions of the embodiments above are only for helping to understand the principles of the embodiments of the present invention. At the same time, for those skilled in the art, there will be changes in the specific implementation methods and application scope based on the embodiments of the present invention. Therefore, the content of this specification should not be construed as a limitation of the present invention.

Claims

1. A rotating rubber active pressure water seal device for a turbine main shaft, characterized in that... It includes a rotating metal ring, a metal annular sealing seat, and a rubber sealing ring. The rotating metal ring is coaxial with the main shaft and is detachably and fixedly connected to the main shaft. The rotating metal ring and the metal annular sealing seat are arranged opposite to each other; The metal annular sealing seat is provided with a sealing seat annular groove on the side facing the rotating metal ring; The upper end of the rubber sealing ring is fixedly connected to the lower side of the rotating metal ring, and its lower part is set in the sealing seat ring groove; The base part of the rubber sealing ring that does not participate in the sealing work by fitting and rotating with the inner and outer ring surfaces of the sealing seat ring groove has a axial cross-sectional width smaller than the width of the rectangular cross-sectional ring groove of the sealing seat, and does not fit with the sealing seat ring groove at all during sealing work. The lower end of the rubber sealing ring is provided with a rubber sealing ring groove and an inner rotating sealing working ring and an outer rotating sealing working ring symmetrically arranged on both sides of the rubber sealing ring groove. The inner and outer rotating sealing working rings are respectively attached to the inner and outer ring surfaces of the sealing seat ring groove under water pressure and rotate during operation.

2. The active pressure water seal device for rotating rubber on the turbine main shaft according to claim 1, wherein the height of the inner rotating seal working ring and the outer rotating seal working ring is less than 30mm.

3. The active pressure water seal device for rotating rubber on the turbine main shaft according to claim 1, characterized in that... The rotating metal ring has a positioning groove on its lower side that mates with the upper end of the rubber sealing ring.

4. The active pressure water seal device for rotating rubber on the turbine main shaft according to claim 3, characterized in that... The rotating metal ring is connected to an aluminum alloy outer ring and an aluminum alloy inner ring on its lower side; the positioning groove is formed between the aluminum alloy outer ring and the aluminum alloy inner ring at intervals.

5. The active pressure water seal device for rotating rubber on the turbine main shaft according to claim 4, characterized in that... The rotating metal ring is detachably connected to the aluminum alloy outer ring and the aluminum alloy inner ring.

6. The active pressure water seal device for rotating rubber on the turbine main shaft according to claim 1, characterized in that... The outer and inner ring surfaces of the sealing seat groove are provided with a wear-resistant coating material to reduce wear.

7. The active pressure water seal device for rotating rubber on the turbine main shaft according to claim 1, characterized in that... The inner and outer rotary sealing working rings are respectively provided with multiple radial pressure lubrication water holes and radial self-lubricating holes on their circumferences, which communicate with the sealing seat ring grooves. Self-lubricating graphite columns are provided in the radial self-lubricating holes.

8. The active pressure water seal device for rotating rubber on the turbine main shaft according to claim 1, characterized in that... The rotating metal ring has multiple screw holes evenly distributed circumferentially on its upper end face, and the screw holes penetrate the upper and lower end faces of the rotating metal ring; a connecting bolt is provided in the screw hole, and the upper end face of the rubber sealing ring is provided with a connecting screw hole for cooperating with the connecting bolt, and the rotating metal ring and the rubber sealing ring are bolted together.

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