Ceramic bearing with micropore runner

Abstract

The utility model relates to the technical field of ceramic bearings, in particular to a ceramic bearing with a micropore runner. The ceramic bearing comprises a ceramic inner ring, a ceramic outer ring, a retainer, a ceramic ball and a dust cover, wherein a first groove is formed in the outer wall of the ceramic inner ring; a second groove is formed in the inner wall of the ceramic outer ring; the ceramic balls are connected to the first grooves of the ceramic inner ring and the second grooves of the ceramic outer ring in a sliding mode. A plurality of first lubricating grease adding micropores communicated with the first groove are formed in the side surface of the ceramic inner ring; a plurality of first through holes are formed in the dustproof cover; the first through hole of the dustproof cover can be communicated with the first lubricating grease adding micropore; and the first through hole of the dustproof cover is detachably and hermetically connected with a first sealing screw. When the ceramic bearing is subjected to lubricating grease supplementing maintenance operation, the dustproof cover does not need to be detached, the needle head of the needle cylinder penetrates through the first through hole to enter the first lubricating grease adding micro hole, then lubricating grease is injected, and the lubricating grease maintenance operation can be completed rapidly and conveniently.

Description

Technical Field

[0001] This application relates to the field of ceramic bearing technology, and in particular to a ceramic bearing with microporous flow channels. Background Technology

[0002] The bearing industry is a core component of high-end equipment, playing a vital supporting role in the national economy. Ceramic materials possess excellent properties such as low density, high temperature resistance, low temperature resistance, wear resistance, corrosion resistance, anti-magnetic and electrical insulation, and oil-free self-lubrication. Compared with traditional metal bearings, all-ceramic bearings reduce friction by 80%, extend life by 3-10 times, and reduce weight by 60%. They are widely used in high-end bearings for mechanical equipment in aerospace, shipbuilding, metallurgy, chemical industry, pharmaceutical synthesis, nuclear magnetic resonance equipment, semiconductors, and other fields.

[0003] The service life of ceramic bearings is primarily affected by the frictional wear between the bearing balls and raceways. When impurities enter the ceramic bearing, they adhere to the bearing balls, causing adhesive wear and abrasive wear, significantly shortening the bearing's service life and operational stability. Therefore, ceramic bearings designed for harsh environments are typically fitted with dust covers to reduce the probability of impurities entering the bearing and extend its service life. In existing ceramic bearings with dust covers, the dust cover is usually embedded between the outer and inner ceramic rings, making disassembly relatively cumbersome. Furthermore, ceramic bearings require regular grease replenishment. Grease minimizes wear, reduces frictional damage to the bearing balls, and extends the bearing's service life. This makes grease replenishment for existing dust-covered ceramic bearings relatively inconvenient. Therefore, this application provides a ceramic bearing with microporous flow channels. Utility Model Content

[0004] To address the relatively cumbersome maintenance process of replenishing grease in existing ceramic bearings with dust covers, this application provides a ceramic bearing with microporous channels.

[0005] The ceramic bearing with microporous flow channels provided in this application is achieved through the following scheme:

[0006] A ceramic bearing with microporous flow channels includes a ceramic inner ring, a ceramic outer ring, a cage, ceramic balls, and a dust cover. The outer wall of the ceramic inner ring has a first groove; the inner wall of the ceramic outer ring has a second groove; the ceramic balls are slidably connected to the first groove of the ceramic inner ring and the second groove of the ceramic outer ring; the side of the ceramic inner ring has several first grease-adding micropores communicating with the first grooves; the dust cover has several first through holes; the first through holes of the dust cover can communicate with the first grease-adding micropores; the first through holes of the dust cover are detachable and sealed with a first sealing screw.

[0007] When performing grease replenishment maintenance on the ceramic bearings in this application, there is no need to remove the dust cover. The grease is injected through the first through hole of the syringe needle into the first grease addition micro-hole. The grease flows into the ceramic ball and the first groove through the first grease addition micro-hole, thus completing the grease maintenance operation quickly and conveniently.

[0008] Preferably, the ceramic outer ring has a plurality of second grease-adding micropores communicating with the second groove on its side; the dust cover has a plurality of second through holes; the second through holes of the dust cover can be connected to the second grease-adding micropores; the second through holes of the dust cover are detachable and sealed with a second sealing screw.

[0009] When performing grease replenishment maintenance on the ceramic bearings in this application, there is no need to remove the dust cover. The grease is injected through the second through hole of the syringe needle into the second grease addition micro-hole. The grease flows into the ceramic ball and the second groove through the second grease addition micro-hole, thus completing the grease maintenance operation quickly and conveniently.

[0010] Preferably, the outer wall of the ceramic inner ring is provided with a left ring groove A and a right ring groove A respectively; the left ring groove A of the ceramic inner ring is provided with a first inner retaining groove, and the right ring groove A of the ceramic inner ring is provided with a second inner retaining groove; the inner wall of the ceramic outer ring is provided with a left ring groove B and a right ring groove B respectively; the left ring groove B of the ceramic outer ring is provided with a first outer retaining groove, and the right ring groove B of the ceramic outer ring is provided with a second outer retaining groove; the dust cover includes a left dust cover and a right dust cover, one end of the left dust cover is engaged with the first inner retaining groove of the ceramic inner ring, and the other end is engaged with the first outer retaining groove of the ceramic outer ring; one end of the right dust cover is engaged with the second inner retaining groove of the ceramic inner ring, and the other end is engaged with the second outer retaining groove of the ceramic outer ring.

[0011] Preferably, the left ring groove A of the ceramic inner ring is machined to form a first chamfer, and a first pry-opening opening is formed between the left dust cover and the first chamfer of the ceramic inner ring; a first snap-fit ​​connector is formed on the inner wall of the left dust cover, and the first snap-fit ​​connector is snapped into the first inner snap-fit ​​groove of the ceramic inner ring.

[0012] Preferably, the right ring groove A of the ceramic inner ring is machined to form a second chamfer; a second pry opening is formed between the right dust cover and the second chamfer of the ceramic inner ring; a third snap-fit ​​connector is formed on the inner wall of the right dust cover, and the third snap-fit ​​connector is snapped into the second inner groove of the ceramic inner ring.

[0013] Preferably, the left ring groove B of the ceramic outer ring is machined to form a third chamfer, and a third pry-opening opening is formed between the left dust cover and the third chamfer of the ceramic outer ring; a second snap-fit ​​connector is formed on the outer wall of the left dust cover, and the second snap-fit ​​connector is snapped into the first outer snap-fit ​​groove of the ceramic outer ring.

[0014] Preferably, the right ring groove B of the ceramic outer ring is machined to form a fourth chamfer, and a fourth pry-opening opening is formed between the right dust cover and the fourth chamfer of the ceramic outer ring; a fourth snap-fit ​​connector is formed on the inner wall of the right dust cover, and the fourth snap-fit ​​connector is snapped into the second outer snap-fit ​​groove of the ceramic outer ring.

[0015] By adopting the above technical solution, it is easy to quickly remove the dust cover for replacement and maintenance of worn ceramic balls.

[0016] Preferably, the first through hole of the dust cover includes a first countersunk hole and a first through hole A connected to the first countersunk hole, the central axis of the first countersunk hole and the central axis of the first through hole A are collinear; the first sealing screw is detachable and sealed to the first countersunk hole; the first through hole A can be connected to the first grease addition micropore.

[0017] Preferably, the second through hole of the dust cover includes a second countersunk hole and a second through hole A connected to the second countersunk hole, wherein the central axis of the second countersunk hole and the central axis of the second through hole A are collinear; the second sealing screw is detachable and sealingly connected to the second countersunk hole; the second through hole A can be connected to the second grease-adding micropore.

[0018] By adopting the above technical solutions, the lubrication maintenance operation can be completed quickly and conveniently, while improving the sealing effect of the dust cover. This effectively prevents dust, dirt and other external particles from entering the bearing, reducing wear and damage, thereby extending the service life of the ceramic bearing and maintaining its performance.

[0019] Preferably, the left dust cover and the right dust cover have the same structure. Taking the left dust cover as an example, the inner circumference of the left dust cover is integrally formed with a first annular groove; a first ceramic ring is embedded in the first annular groove of the left dust cover; the first ceramic ring is in contact with the left annular groove A of the inner ceramic ring; the outer circumference of the left dust cover is integrally formed with a second annular groove; a second ceramic ring is embedded in the second annular groove of the left dust cover; the second ceramic ring is in contact with the left annular groove B of the outer ceramic ring; the left dust cover is detachable and rotatably connected between the inner ceramic ring and the outer ceramic ring; the right dust cover is detachable and rotatably connected between the inner ceramic ring and the outer ceramic ring.

[0020] The first and second ceramic rings in this application improve the sealing effect of the dust cover, better prevent dust, dirt and other external particles from entering the bearing, reduce wear and damage, thereby extending the service life of the ceramic bearing and maintaining its performance.

[0021] In summary, this application has the following advantages:

[0022] 1. When performing grease replenishment maintenance on the ceramic bearing in this application, there is no need to remove the dust cover. The grease is injected through the first through hole of the syringe needle into the first grease addition microhole, which can quickly and conveniently complete the grease maintenance operation.

[0023] 2. When performing grease replenishment maintenance on the ceramic bearings in this application, there is no need to remove the dust cover. The grease can be injected by inserting the syringe needle through the second through hole into the second grease addition microhole, thus completing the grease maintenance operation quickly and conveniently. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of the overall structure of a ceramic bearing with microporous flow channels in an embodiment of this application.

[0025] Figure 2 yes Figure 1 A magnified view of a portion of point A in the middle.

[0026] Figure 3 yes Figure 1 A magnified view of a section at point B.

[0027] Figure 4 yes Figure 1 A magnified view of a section at point C.

[0028] Figure 5 yes Figure 1 A magnified view of a section at point D.

[0029] In the diagram, 1. Ceramic inner ring; 11. First groove; 12. First grease-adding micropore; 13. Left ring groove A; 131. First inner retaining groove; 132. First chamfer; 133. First pry-opening opening; 14. Right ring groove A; 141. Second inner retaining groove; 142. Second chamfer; 143. Second pry-opening opening; 2. Ceramic outer ring; 21. Second groove; 22. Second grease-adding micropore; 23. Left ring groove B; 231. First outer retaining groove; 232. Third chamfer; 233. Third pry-opening opening; 24. Right ring groove B; 241. Fourth chamfer; 242. Fourth pry-opening opening; 241. 3. Second outer slot; 4. Cage; 5. Ceramic ball; 6. Dust cover; 7. Left dust cover; 8. First locking connector; 9. Second locking connector; 10. First ring groove; 11. First ceramic ring; 12. Second ring groove; 13. Second ceramic ring; 14. Right dust cover; 15. Third locking connector; 16. Fourth locking connector; 17. First through hole; 18. First countersunk hole; 19. First through hole A; 20. Second through hole; 21. Second countersunk hole; 22. Second through hole A; 23. First sealing screw; 44. Second sealing screw. Detailed Implementation

[0030] The technical solution of this application will be further described in detail below with reference to the accompanying drawings and embodiments.

[0031] Example: Refer to Figure 1 A ceramic bearing with microporous flow channels includes a ceramic inner ring 1, a ceramic outer ring 2, a cage 3, ceramic balls 4, and a dust cover 5. The ceramic balls 4 are placed in the cage 3, and the cage 3 is assembled between the ceramic inner ring 1 and the ceramic outer ring 2, so that the ceramic balls 4 are equidistantly spaced within the ceramic inner ring 1 and the ceramic outer ring 2. A first groove 11 is formed on the outer wall of the ceramic inner ring 1, and a second groove 21 is formed on the inner wall of the ceramic outer ring 2. The ceramic balls 4 are slidably connected to the first groove 11 of the ceramic inner ring 1 and the second groove 21 of the ceramic outer ring 2.

[0032] Reference Figure 1 The ceramic inner ring 1 has several first grease-adding micropores 12 communicating with the first groove 11 on its side. The dust cover 5 is made of fluororubber and has several first through holes 51, the number of which is equal to the number of the first grease-adding micropores 12. During the assembly of the ceramic bearing, the central axis of the first through hole 51 of the dust cover 5 is collinear with the central axis of the first grease-adding micropore 12, and the first through hole 51 of the dust cover 5 can communicate with the first grease-adding micropore 12. To ensure the dustproof sealing effect of the dust cover 5, the first through hole 51 of the dust cover 5 is detachably and sealed with a first sealing screw 6.

[0033] Reference Figure 1The ceramic outer ring 2 has several second grease-adding micropores 22 on its side, which communicate with the second groove 21. The dust cover 5 has several second through holes 52, the number of which is equal to the number of second grease-adding micropores 22. During ceramic bearing assembly, the central axis of the second through holes 52 of the dust cover 5 is collinear with the central axis of the second grease-adding micropores 22, and the second through holes 52 of the dust cover 5 can communicate with the second grease-adding micropores 22. To ensure the dustproof sealing effect of the dust cover 5, the second through holes 52 of the dust cover 5 are detachably and sealed with second sealing screws 60.

[0034] Reference Figure 1 The dust cover 5 includes a left dust cover 501 and a right dust cover 502. One end of the left dust cover 501 is engaged with the first inner groove 131 of the inner ceramic ring 1, and the other end is engaged with the first outer groove 231 of the outer ceramic ring 2. One end of the right dust cover 502 is engaged with the second inner groove 141 of the inner ceramic ring 1, and the other end is engaged with the second outer groove 241 of the outer ceramic ring 2.

[0035] Reference Figure 2 and Figure 4 The outer circumference of the ceramic inner ring 1 is provided with a left ring groove A13 and a right ring groove A14. The left ring groove A13 of the ceramic inner ring 1 has a first inner retaining groove 131 on its side wall. The groove opening of the left ring groove A13 is machined to form a first chamfer 132. A first pry opening 133 is formed between the left dust cover 501 and the first chamfer 132 of the ceramic inner ring 1. The right ring groove A14 of the ceramic inner ring 1 has a second inner retaining groove 141 on its side wall. The groove opening of the right ring groove A14 of the ceramic inner ring 1 is machined to form a second chamfer 142. A second pry opening 143 is formed between the right dust cover 502 and the second chamfer 142 of the ceramic inner ring 1.

[0036] Reference Figure 3 and Figure 5 The inner wall of the ceramic outer ring 2 is provided with a left ring groove B23 and a right ring groove B24. The left ring groove B23 of the ceramic outer ring 2 has a first external retaining groove 231 on its side wall. The groove opening of the left ring groove B23 is machined to form a third chamfer 232, and a third pry opening 233 is formed between the left dust cover 501 and the third chamfer 232 of the ceramic outer ring 2. The right ring groove B24 of the ceramic outer ring 2 has a second external retaining groove 241 on its side wall. The groove opening of the right ring groove B24 of the ceramic outer ring 2 is machined to form a fourth chamfer 242, and a fourth pry opening 243 is formed between the right dust cover 502 and the fourth chamfer 242 of the ceramic outer ring 2.

[0037] Reference Figure 2 and Figure 4The left dust cover 501 has a first snap-fit ​​connector 5011 formed on its inner wall, which snaps into the first inner slot 131 of the ceramic inner ring 1. The left dust cover 501 also has a second snap-fit ​​connector 5012 formed on its outer wall, which snaps into the first outer slot 231 of the ceramic outer ring 2. This structure allows the left dust cover 501 to be detachably and sealingly connected between the ceramic inner ring 1 and the ceramic outer ring 2. To remove the left dust cover 501, a flathead screwdriver can be used to pry it open through the first pry opening 133 or the second pry opening 143.

[0038] Reference Figure 3 and Figure 5 The inner wall of the right dust cover 502 has a third locking connector 5021, which engages with the second inner groove 141 of the ceramic inner ring 1. The inner wall of the right dust cover 502 also has a fourth locking connector 5022, which engages with the second outer groove 241 of the ceramic outer ring 2. This structure allows the right dust cover 502 to be detachably and sealingly connected between the ceramic inner ring 1 and the ceramic outer ring 2. To remove the right dust cover 502, a flathead screwdriver can be used to pry it open through the third pry opening 233 or the fourth pry opening 243.

[0039] Reference Figure 2 and Figure 4 The dust cover 5 has a first through hole 51, which includes a first countersunk hole 511 and a first through hole A512 connected to the first countersunk hole 511. The central axis of the first countersunk hole 511 and the central axis of the first through hole A512 are collinear. The first sealing screw 6 is detachably and sealingly connected to the first countersunk hole 511, specifically by a threaded connection. The first through hole A512 can be connected to the first grease-adding micro-hole 12. When performing grease replenishment maintenance on the ceramic bearing, it is not necessary to remove the dust cover 5. The first sealing screw 6 is removed with a Phillips screwdriver, and grease is injected through the first through hole 51 into the first grease-adding micro-hole 12 via a syringe needle. The grease flows through the first grease-adding micro-hole 12 into the space between the ceramic ball 4 and the first groove 11, thus completing the grease maintenance operation quickly and conveniently.

[0040] Reference Figure 3 and Figure 5The second through hole 52 of the dust cover 5 includes a second countersunk hole 521 and a second through hole A522 connected to the second countersunk hole 521. The central axis of the second countersunk hole 521 and the central axis of the second through hole A522 are collinear. The second sealing screw 60 is detachably and sealingly connected to the second countersunk hole 521, specifically by a threaded connection. The second through hole A522 can be connected to the second grease-adding micro-hole 22. When performing grease replenishment maintenance on the ceramic bearing, it is not necessary to remove the dust cover 5. Use a Phillips screwdriver to remove the second sealing screw 60, insert the syringe needle through the first through hole 51 into the second grease-adding micro-hole 22, and inject grease. The grease flows through the second grease-adding micro-hole 22 into the space between the ceramic ball 4 and the second groove 21, thus completing the grease maintenance operation quickly and conveniently.

[0041] Reference Figure 1 The left dust cover 501 and the right dust cover 502 have the same structure. Taking the left dust cover 501 as an example, a first annular groove 5013 is integrally formed on the inner circumference of the left dust cover 501. A first ceramic ring 5014 is embedded in the first annular groove 5013 of the left dust cover 501. The first ceramic ring 5014 contacts the side wall of the left annular groove A13 of the inner ceramic ring 1, which can achieve a good sealing and dustproof effect. A second annular groove 5015 is integrally formed on the outer circumference of the left dust cover 501. A second ceramic ring 5016 is embedded in the second annular groove 5015 of the left dust cover 501. The second ceramic ring 5016 contacts the side wall of the left annular groove B23 of the outer ceramic ring 2, which can achieve a good sealing and dustproof effect. The left dust cover 501 is detachably and rotatably connected between the ceramic inner ring 1 and the ceramic outer ring 2, and the right dust cover 502 is detachably and rotatably connected between the ceramic inner ring 1 and the ceramic outer ring 2. This effectively prevents dust, dirt and other external particles from entering the bearing, reducing wear and damage, thereby extending the service life of the ceramic bearing and maintaining its performance.

[0042] The embodiments described in this specific implementation are preferred embodiments of this application and are not intended to limit the scope of protection of this application. Therefore, all equivalent changes made in accordance with the structure, shape and principle of this application should be covered within the scope of protection of this application.

Claims

1. A ceramic bearing having a micro-porous flow channel, characterized by: The device includes a ceramic inner ring (1), a ceramic outer ring (2), a retainer (3) disposed between the ceramic inner ring (1) and the ceramic outer ring (2), ceramic balls (4), and a dust cover (5). The outer wall of the ceramic inner ring (1) is provided with a first groove (11); the inner wall of the ceramic outer ring (2) is provided with a second groove (21); the ceramic balls (4) are slidably connected to the first groove (11) of the ceramic inner ring (1) and the second groove (21) of the ceramic outer ring (2); the side of the ceramic inner ring (1) is provided with a plurality of first grease-adding micropores (12) communicating with the first groove (11); the dust cover (5) is provided with a plurality of first through holes (51); the first through holes (51) of the dust cover (5) can be connected to the first grease-adding micropores (12); the first through holes (51) of the dust cover (5) are detachable and sealed with a first sealing screw (6).

2. A ceramic bearing having micro-porous flow channels as claimed in claim 1, wherein: The ceramic outer ring (2) has several second grease-adding micropores (22) that communicate with the second groove (21) on its side; the dust cover (5) has several second through holes (52); the second through holes (52) of the dust cover (5) can be connected to the second grease-adding micropores (22); the second through holes (52) of the dust cover (5) are detachable and sealed with a second sealing screw (60).

3. The ceramic bearing having micro-porous flow channels of claim 1, wherein: The outer wall of the ceramic inner ring (1) is provided with a left annular groove A (13) and a right annular groove A (14); the left annular groove A (13) of the ceramic inner ring (1) is provided with a first inner retaining groove (131), and the right annular groove A (14) of the ceramic inner ring (1) is provided with a second inner retaining groove (141); the inner wall of the ceramic outer ring (2) is provided with a left annular groove B (23) and a right annular groove B (24); the left annular groove B (23) of the ceramic outer ring (2) is provided with a first outer retaining groove (231), and the ceramic outer ring (2) is provided with a second inner retaining groove (141). The right ring groove B (24) has a second outer groove (241) on its side wall; the dust cover (5) includes a left dust cover (501) and a right dust cover (502). One end of the left dust cover (501) is engaged with the first inner groove (131) of the ceramic inner ring (1), and the other end is engaged with the first outer groove (231) of the ceramic outer ring (2); one end of the right dust cover (502) is engaged with the second inner groove (141) of the ceramic inner ring (1), and the other end is engaged with the second outer groove (241) of the ceramic outer ring (2).

4. A ceramic bearing having micro-porous flow channels as defined in claim 3, wherein: The left ring groove A (13) of the ceramic inner ring (1) is machined to form a first chamfer (132), and a first pry opening (133) is formed between the left dust cover (501) and the first chamfer (132) of the ceramic inner ring (1); a first snap-fit ​​connector (5011) is formed on the inner wall of the left dust cover (501), and the first snap-fit ​​connector (5011) is snapped into the first inner slot (131) of the ceramic inner ring (1).

5. A ceramic bearing having micro-porous flow channels as defined in claim 3, wherein: The right ring groove A (14) of the ceramic inner ring (1) is machined to form a second chamfer (142); a second pry opening (143) is formed between the right dust cover (502) and the second chamfer (142) of the ceramic inner ring (1); a third snap-fit ​​connector (5021) is formed on the inner wall of the right dust cover (502), and the third snap-fit ​​connector (5021) is snapped into the second inner slot (141) of the ceramic inner ring (1).

6. A ceramic bearing having micro-porous flow channels as defined in claim 3, wherein: The left ring groove B (23) of the ceramic outer ring (2) is machined to form a third chamfer (232), and a third pry opening (233) is formed between the left dust cover (501) and the third chamfer (232) of the ceramic outer ring (2); a second snap connector (5012) is formed on the outer wall of the left dust cover (501), and the second snap connector (5012) is snapped into the first outer slot (231) of the ceramic outer ring (2).

7. A ceramic bearing with microporous flow channels according to claim 3, characterized in that: The right ring groove B (24) of the ceramic outer ring (2) is machined to form a fourth chamfer (242), and a fourth pry opening (243) is formed between the right dust cover (502) and the fourth chamfer (242) of the ceramic outer ring (2); a fourth snap connector (5022) is formed on the inner wall of the right dust cover (502), and the fourth snap connector (5022) is snapped into the second outer slot (241) of the ceramic outer ring (2).

8. The ceramic bearing having micro-porous flow channels of claim 1, wherein: The first through hole (51) of the dust cover (5) includes a first countersunk hole (511) and a first through hole A (512) connected to the first countersunk hole (511). The central axis of the first countersunk hole (511) and the central axis of the first through hole A (512) are collinear. The first sealing screw (6) is detachable and sealed to the first countersunk hole (511). The first through hole A (512) can be connected to the first grease adding micropore (12).

9. The ceramic bearing having micro-porous flow channels of claim 2, wherein: The second through hole (52) of the dust cover (5) includes a second countersunk hole (521) and a second through hole A (522) connected to the second countersunk hole (521). The central axis of the second countersunk hole (521) and the central axis of the second through hole A (522) are collinear. The second sealing screw (60) is detachable and sealed to the second countersunk hole (521). The second through hole A (522) can be connected to the second grease adding micropore (22).

10. The ceramic bearing having micro-porous flow channels of claim 3, wherein: The left dust cover (501) and the right dust cover (502) have the same structure. Taking the left dust cover (501) as an example, the left dust cover (501) has a first annular groove (5013) integrally formed on its inner circumference; a first ceramic ring (5014) is embedded in the first annular groove (5013) of the left dust cover (501); the first ceramic ring (5014) is in contact with the left annular groove A (13) of the inner ceramic ring (1); the left dust cover (501) has an integrally formed outer circumference. The type has a second annular groove (5015); a second ceramic ring (5016) is embedded in the second annular groove (5015) of the left dust cover (501); the second ceramic ring (5016) is in contact with the left annular groove B (23) of the outer ceramic ring (2); the left dust cover (501) is detachable and rotatably connected between the inner ceramic ring (1) and the outer ceramic ring (2); the right dust cover (502) is detachable and rotatably connected between the inner ceramic ring (1) and the outer ceramic ring (2).

Images