A high-protection explosion-proof cable entry device and its sealing method

Abstract

The present invention discloses a highly protective explosion-proof cable entry device and its sealing method. The structures of the sealing ring and the inner hole of the boss are redesigned, greatly improving the sealing effect, enabling the protection level to reach IP68, allowing it to be used underwater, and having more reliable sealing; the maximum compression rate of the sealing ring is specified, a sealing material with excellent performance is selected, and a limiting measure is adopted for the screwing position of the compression nut, significantly improving the service life; the compression nut adopts a loosening prevention measure, which can effectively avoid sealing failure. Through the above measures, the present invention effectively solves the disadvantages existing in the existing explosion-proof cable entry devices.

Description

Technical Field

[0001] The present invention relates to an explosion-proof cable inlet device, and more particularly to a high-protection explosion-proof cable inlet device and its sealing method. Background Art

[0002] The function of an explosion-proof cable inlet device is to seal various cables introduced into and led out of an electrical box, preventing harmful substances such as various fine particles and liquids from entering the electrical box, and it is mainly applied in flammable and explosive dangerous places. The environment in such dangerous places is very harsh, and there are usually a large number of fine particle dust, corrosive gas liquids, sunlight aging, and rain erosion. Currently, the existing explosion-proof cable inlet devices often have the problem of sealing failure, resulting in the entry of harmful substances such as various dusts and liquids into the electrical box, ultimately leading to faults in the electrical box and affecting the normal operation of the equipment it controls. The existing explosion-proof cable inlet devices mainly consist of: a boss on the housing and its cylindrical inner hole, a cylindrical sealing ring, a gasket, and a compression nut. During assembly, the sealing ring and the gasket are sequentially installed in the cylindrical inner hole of the boss, and then the compression nut is screwed into the inner hole and tightened, thus achieving the sealing of the cables introduced into and led out of the electrical box. Its sealing performance is achieved through the sealing joint surface, and there are a total of 2 sealing joint surfaces: the joint surface between one end face of the sealing ring and the bottom end face of the inner hole of the boss, and the joint surface between the inner hole side wall of the sealing ring and the outer surface of the cable. Since there are only 2 sealing joint surfaces, the sealing effect is not very good, the protection level is low and it is difficult to reach IP65 level, and it is even more impossible to be used underwater; also, due to the lack of a limiting measure for the screwing position of the compression nut, the sealing ring is easily over-compressed, and the material performance of the sealing ring is poor, resulting in a relatively short service life; also, since the compression nut has no anti-loosening measure, especially when applied in a vibrating place, it is very easy for the compression nut to loosen, resulting in sealing failure.

[0003] In summary, the existing explosion-proof cable inlet devices have the following disadvantages: poor sealing effect, low protection level, inability to be used underwater, short service life, and easy sealing failure. Therefore, those skilled in the art have provided a high-protection explosion-proof cable inlet device and its sealing method to solve the problems raised in the above background art. Summary of the Invention

[0004] To solve the above technical problems, the present invention provides a high-protection explosion-proof cable inlet device and its sealing method, including a housing. One side of the housing is provided with a boss, one side of the boss is provided with an outer end face, the inside of the boss is provided with a second inner hole, the inside of the second inner hole is provided with an upper part, the upper part is provided with a first sealing groove, a second sealing groove, and a third sealing groove, the inside of the second inner hole on one side of the upper part is provided with an internal thread, and the internal thread extends from the outer end face of the boss only to the third sealing groove. One side of the second inner hole is provided with a second step, one side of the second step is provided with a bottom, and one side of the bottom is provided with a bottom end face;

[0005] The inner hole 2 is provided with a sealing ring, the sealing ring includes a front end and a rear end, the front end and the rear end are provided with an inner hole 1, a step 1 is provided between the front end and the rear end, a front end face is provided on one side of the front end, a rear end face is provided on one side of the rear end, and sealing ribs 1, 2 and 3 are provided on the outer side of the rear end, the bottom and the front end are elliptical, and the rear end and the upper part are circular;

[0006] The sealing rib 1 is located inside the sealing groove 1 to form a sealing joint surface 3, the sealing rib 2 is located inside the sealing groove 2 to form a sealing joint surface 4, the sealing rib 3 is located inside the sealing groove 3 to form a sealing joint surface 5, and a displacement space is provided between the sealing rib 1 and the sealing groove 1, between the sealing rib 2 and the sealing groove 2, and between the sealing rib 3 and the sealing groove 3;

[0007] A clamping nut is provided inside the inner hole 2 on one side of the sealing ring, the clamping nut includes a top and a nut, an inner hole 3 is provided inside the top and the nut, an external thread is provided on the outside of the top, an anti-loosening end face is provided on one side of the nut, and a multi-layer wave spring is provided on one side of the anti-loosening end face, the multi-layer wave spring includes a plurality of spring leaves that cross each other to form wave crests and wave troughs;

[0008] Cables are inserted into the inner holes one, two and three. The front end face and the bottom end face form a sealing joint surface one. The step one and the step two form a sealing joint surface two. The sealing ring and the cable form a sealing joint surface six.

[0009] Preferably, a gasket is provided between the sealing ring and the clamping nut.

[0010] Preferably, the sealing ring is made of silicone and is added with metal antioxidants and anti-ultraviolet agents.

[0011] Preferably, the hardness of the sealing ring is maintained at 50-55 degrees Shore.

[0012] A sealing method for the above-mentioned high-protection explosion-proof cable entry device comprises the following steps:

[0013] (1) After assembling the sealing ring to the inner hole of the boss, insert the cable into the inner hole of the sealing ring;

[0014] (2) Place the gasket on the rear end face of the sealing ring, then insert the outer thread of the clamping nut into the inner diameter of the multi-layer wave spring, then screw the outer thread of the clamping nut into the inner thread of the boss, then insert the cable into the inner hole of the clamping nut and into the shell, then fix the torque wrench on the hexagonal nut of the clamping nut and tighten it according to the specified torque. At this time, the peaks and troughs of one end of the multi-layer wave spring fit with the outer end face of the boss, and the peaks and troughs of the other end fit with the peaks and troughs of the anti-loosening end face of the clamping nut, and make the peaks of the clamping nut correspond to the troughs of the multi-layer wave spring.

[0015] Technical effects and advantages of the present invention:

[0016] 1. The present invention has up to 6 sealing joints, with high sealing performance, an IP68 high protection level, and can be used underwater for 20 meters for a long time, effectively protecting nano-scale microparticles, various harmful liquids, rainwater, etc.

[0017] 2. The present invention has a high safety redundancy and more reliable sealing due to the misalignment of the relative positions of the sealing grooves in the inner hole of the housing boss and the sealing ribs of the sealing ring, as well as the difference in the semi-circular diameters.

[0018] 3. The present invention is designed to be oval to effectively prevent the sealing ring and the cable from being twisted.

[0019] 4. The present invention has a long service life, good weather resistance, and a wide variety of corrosion-resistant solvents for the sealing ring by setting the maximum compression amount of the sealing ring, selecting excellent sealing materials, and limiting the screwing position of the compression nut.

[0020] 5. The present invention can effectively avoid seal failure by setting a lock washer end face on the compression nut and arranging multiple layers of wave springs.

[0021] 6. The present invention can effectively protect the cable and clamp the cable by setting a reasonable hardness of the sealing ring. Description of the Drawings

[0022] Figure 1 is a schematic structural diagram of the sealing ring provided by the present application;

[0023] Figure 2 is a schematic structural diagram of the housing boss provided by the present application;

[0024] Figure 3 is a schematic structural diagram of the compression nut provided by the present application;

[0025] Figure 4 is a schematic structural diagram of the multi-layer wave spring provided by the present application;

[0026] Figure 5 is a schematic structural diagram of the assembly drawing provided by the present application;

[0027] In the figure:

[0028] 1. Step 1; 2. Sealing rib 1; 3. Sealing rib 2; 4. Sealing rib 3; 5. Rear end face; 6. Inner hole 1; 9. Front end face; 10. Front end; 11. Rear end; 14. Bottom end face; 15. Step 2; 16. Boss; 17. Sealing groove 1; 18. Sealing groove 2; 19. Sealing groove 3; 20. Outer end face; 21. Inner hole 2; 22. Internal thread; 23. Upper part; 24. Bottom; 25. Housing; 26. Top; 27. External thread; 28. Locking end face; 29. Inner hole 3; 30. Crest; 31. Trough; 32. Nut; 35. Displacement space; 36. Sealing joint surface 1; 37. Sealing joint surface 2; 38. Sealing joint surface 3; 39. Sealing joint surface 4; 40. Sealing joint surface 5; 41. Sealing joint surface 6; 42. Cable; 43. Compression nut; 44. Multi-layer corrugated spring; 45. Gasket; 46. Sealing ring. Detailed implementation mode

[0029] The present invention will be further described in detail below in conjunction with the drawings and specific implementation modes. The embodiments of the present invention are given for the purpose of illustration and description, and are not exhaustive or limited to the disclosed form. Many modifications and variations will be obvious to those of ordinary skill in the art. The embodiments are selected and described to better illustrate the principles and practical applications of the present invention, and to enable those of ordinary skill in the art to understand the present invention and thus design various embodiments with various modifications suitable for specific purposes.

[0030] Please refer to Figures 1 to 5 , in this embodiment, a highly protected explosion-proof cable entry device is provided, including a housing 25. A boss 16 is provided on one side of the housing 25. An outer end face 20 is provided on one side of the boss 16. An inner hole 21 is provided inside the boss 16. An upper part 23 is provided inside the inner hole 21. Sealing grooves 17, 18, and 19 are provided inside the upper part 23. An internal thread 22 is provided on one side of the inner hole 21 inside the upper part 23. The internal thread 22 extends from the outer end face 20 of the boss 16 only to the sealing groove 19. A step 2 15 is provided on one side of the inner hole 21. A bottom 24 is provided on one side of the step 2 15. A bottom end face 14 is provided on one side of the bottom 24;

[0031] A sealing ring 46 is provided inside the inner hole 21. The sealing ring 46 is made of silica gel and added with metal antioxidants and anti-ultraviolet agents. The hardness of the sealing ring 46 is maintained at 50-55 Shore degrees. The sealing ring 46 includes a front end 10 and a rear end 11. An inner hole 1 6 is provided inside the front end 10 and the rear end 11. A step 1 is provided between the front end 10 and the rear end 11. A front end face 9 is provided on one side of the front end 10. A rear end face 5 is provided on one side of the rear end 11. Sealing ribs 1, 2, and 3 are provided on the outside of the rear end 11. The bottom 24 and the front end 10 are oval, and the rear end 11 and the upper part 23 are circular;

[0032] The first sealing rib 2 is located inside the first sealing groove 17 to form the third sealing joint surface 38. The second sealing rib 3 is located inside the second sealing groove 18 to form the fourth sealing joint surface 39. The third sealing rib 4 is located inside the third sealing groove 19 to form the fifth sealing joint surface 40. A displacement space 35 is provided between the first sealing rib 2 and the first sealing groove 17, between the second sealing rib 3 and the second sealing groove 18, and between the third sealing rib 4 and the third sealing groove 19.

[0033] A pressing nut 43 is provided on one side of the sealing ring 46 inside the second inner hole 21. A gasket 45 is provided between the sealing ring 46 and the pressing nut 43. The pressing nut 43 includes a top end 26 and a nut 32. An inner hole three 29 is provided inside the top end 26 and the nut 32. An external thread 27 is provided on the outside of the top end 26. A lock prevention end face 28 is provided on one side of the nut 32. A multi-layered wave spring 44 is provided on one side of the lock prevention end face 28. The multi-layered wave spring 44 includes a plurality of spring pieces that cross each other to form wave crests 30 and wave troughs 31.

[0034] A cable 42 is inserted into the first inner hole 6, the second inner hole 21, and the third inner hole 29. The front end face 9 and the bottom end face 14 form the first sealing joint surface 36. The first step 1 and the second step 15 form the second sealing joint surface 37. A sixth sealing joint surface 41 is formed between the sealing ring 46 and the cable 42.

[0035] A sealing method for the high-protection explosion-proof cable inlet device described above includes the following steps:

[0036] (1). After assembling the sealing ring 46 into the second inner hole 21 of the boss 16, the cable 42 is passed through the first inner hole 6 of the sealing ring 46.

[0037] (2). The gasket 45 is placed on the rear end face 5 of the sealing ring 46. Then, the external thread 27 of the pressing nut 43 is passed through the inner diameter of the multi-layered wave spring 44. Then, the external thread 27 of the pressing nut 43 is screwed into the internal thread 22 of the boss 16. Then, the cable 42 is passed through the third inner hole 29 of the pressing nut 43 and into the inside of the housing 25. Then, a torque wrench is fixed on the hexagonal nut 32 of the pressing nut 43 and tightened according to the specified torque. At this time, the wave crests 30 and wave troughs 31 at one end of the multi-layered wave spring 44 are in contact with the outer end face of the boss 16, and the wave crests 30 and wave troughs 31 at the other end are in contact with the wave crests 30 and wave troughs 31 of the lock prevention end face 28 of the pressing nut 43, and the wave crests 30 of the pressing nut 43 correspond to the wave troughs 31 of the multi-layered wave spring 44.

[0038] 1. Redesigned the structures of the sealing ring and the second inner hole of the boss on the housing.

[0039] 1.1 The front end of the sealing ring is designed as an ellipse, and the rear end is designed as a cylinder. The major axis diameter of the ellipse is smaller than the outer diameter of the cylinder. Therefore, a step one is formed at the junction of the ellipse and the cylinder. A sealing rib one with a semi-circular cross-section is provided 3 mm away from step one on the outer surface of the cylinder. Then, sealing ribs two and three with semi-circular cross-sections are sequentially arranged at intervals of 3 mm. A circular inner hole one, which is a through hole, is provided at the center of the sealing ring 46.

[0040] 1.2 The bottom of the inner hole of the boss on the housing is designed as an ellipse, and the upper part is designed as a cylinder. The major axis diameter of the ellipse is smaller than the outer diameter of the cylinder. Therefore, a step two is formed at the junction of the ellipse and the cylinder. A sealing groove one with a semi-circular cross-section is provided 2 mm away from step two in the cylindrical part of the inner hole. Then, sealing grooves two and three with semi-circular cross-sections are sequentially arranged at intervals of 3 mm on the outer surface of the cylinder. The diameter of the semi-circle of the sealing groove is 1 mm larger than that of the semi-circle of the sealing rib. An internal thread is provided in the inner hole of the boss, and the internal thread only extends from the outer end face of the boss to sealing groove three and does not continue to extend.

[0041] 1.3 After assembling the sealing ring into the inner hole of the boss, at this time: the rear end face of the sealing ring is 8 mm higher than the position of sealing groove three; the front end face of the sealing ring fits together with the bottom end face of the inner hole of the boss to form a sealing joint surface one; the step one of the sealing ring fits together with the step two of the inner hole of the boss to form a sealing joint surface two; the sealing ribs one, two, and three of the sealing ring respectively fit together with the sealing grooves one, two, and three of the inner hole of the boss to form sealing joint surfaces three, four, and five; after passing the cable through the inner hole of the sealing ring, the inner hole side wall of the sealing ring fits together with the outer surface of the cable to form a sealing joint surface six. Therefore, a total of 6 sealing joint surfaces are available, which is 3 times that of the existing explosion-proof cable entry device, effectively and significantly improving the sealing performance.

[0042] 2. Set the compression rate of the sealing ring, and select a sealing ring made of excellent performance material.

[0043] 2.1 The total length of the sealing ring is set to be not less than 28 mm, of which the length of the ellipse is not less than 6 mm and the length of the cylinder is not less than 22 mm. The maximum effective compression rate of the sealing ring is 40%. The diameter of the central inner hole of the sealing ring is set to 12 mm. When the compression amount of the sealing ring is 8 mm, that is, the compression rate is 28.5%, the minimum outer diameter of the cable that can be effectively clamped and reliably sealed is 7 mm. At this time, the compression rate does not exceed the effective compression rate range. Therefore, the maximum compression rate of the sealing ring is specified as 28.5%, that is, the compression amount is 8 mm.

[0044] 2.2 The material of the sealing ring is selected as silicone rubber of Wacker brand in Germany, which has excellent performance in aspects such as temperature and humidity resistance range, solvent resistance, resilience, etc., and a certain proportion of antioxidant and ultraviolet inhibitor of metal oxide type is added during the secondary vulcanization process; the oven is heated to the specified temperature, and then the sealing ring is placed in the oven for the specified time to control the hardness of the sealing ring at 50-55 Shore A degrees. This hardness can effectively avoid the situation of pinching the cable insulation layer or insufficient clamping force. Because if the hardness of the sealing ring is too high, the corresponding clamping force will be relatively large, and the cable insulation layer may be pinched when the compression nut is tightened; if the hardness of the sealing ring is too low, the corresponding clamping force will be relatively small, and the clamping force on the cable may be insufficient to effectively clamp the cable when the compression nut is tightened, and the cable will loosen when it is pulled, resulting in seal failure.

[0045] 3. The end face of the compression nut is provided with an anti-loosening structure and multiple layers of corrugated springs are provided.

[0046] 3.1 One end of the compression nut is provided with an external thread, and the other end is a hexagonal nut, which is convenient for the torque wrench to fix when tightening the compression nut; the joint of the external thread and the hexagonal nut is the anti-loosening end face, and 6 wave peaks and 6 wave valleys are evenly distributed on the anti-loosening end face, and the height from the wave peak to the wave valley is 2 mm; a circular inner hole three and it is a through hole is provided at the center of the compression nut.

[0047] 3.2 The effective load of the multiple layers of corrugated springs is 5-10 N, and 6 wave peaks and 6 wave valleys are evenly distributed on both end faces, and the height from the wave peak to the wave valley is 2 mm. The inner diameter and outer diameter of the multiple layers of corrugated springs are the same as the inner diameter and outer diameter of the wave peaks and wave valleys of the compression nut; the material of the multiple layers of corrugated springs is selected as high-strength and corrosion-resistant high-quality stainless steel, which can effectively ensure a relatively long service life in the harsh environment of flammable and explosive dangerous places.

[0048] 3.3 Place the gasket on the rear end face of the sealing ring. Then, insert the external thread of the compression nut into the inner diameter of the multi-layer corrugated spring. Next, screw the external thread of the compression nut into the internal thread of the housing boss. Then, pass the cable through the inner hole of the compression nut and into the interior of the housing. Then, fix the torque wrench on the hexagonal nut of the compression nut and tighten it according to the specified torque. At this time, the peaks and valleys at one end of the multi-layer corrugated spring are in contact with the outer end face of the housing boss, and the peaks and valleys at the other end are in contact with the peaks and valleys of the anti-loosening end face of the compression nut, and the peaks of the compression nut correspond to the valleys of the multi-layer corrugated spring. At this time, the multi-layer corrugated spring has been compressed to generate a reaction force of 5 - 10 N in the screwing direction of the compression nut. Also, because the height from all peaks to valleys is 2 mm, it plays a limiting role in the free rotation of the compression nut. Therefore, it can effectively ensure that the compression nut cannot rotate freely after being tightened, resulting in loosening. Also, because the multi-layer corrugated spring itself has good seismic performance, it further effectively ensures that the compression nut cannot rotate freely after being tightened in a vibrating environment, resulting in loosening. Therefore, it can effectively avoid seal failure and make the seal more reliable.

[0049] 3.4 After the compression nut is tightened, sealing joint surface one, sealing joint surface two, sealing joint surface three, sealing joint surface four, sealing joint surface five, and sealing joint surface six are all effectively tightened and reliable sealing is achieved. Therefore, these 6 sealing joint surfaces can effectively ensure that the protection level reaches IP68, can be used underwater for 20 meters for a long time, and can effectively protect nano-scale microparticles, thus achieving high sealing performance and high protection level.

[0050] 3.5 After the compression nut is tightened, the top end of the compression nut has been screwed into the position of sealing groove three. At this time, the compression rate of the sealing ring is 28.5%, that is, the compression amount is 8 mm, which can effectively clamp the cable with an outer diameter of 7 mm and achieve reliable sealing. Since the internal thread of the housing boss only reaches sealing groove three, the compression nut cannot be screwed in further. This plays a limiting role in the screwing position of the compression nut, that is, the compression nut cannot be screwed in further even with a greater torque, thus effectively ensuring that the sealing ring will not be over-compressed. Therefore, it effectively ensures that the maximum compression rate of the sealing ring after the compression nut is tightened is 28.5%, which does not exceed the effective compression rate of the sealing ring and is in a "light load" condition. Therefore, the service life of the sealing ring is effectively improved.

[0051] Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art and related fields without creative efforts shall fall within the protection scope of the present invention. The structures, devices, and operation methods not specifically described and explained in the present invention shall be implemented according to the conventional means in the art without special instructions and limitations.

Claims

1. A high-protection explosion-proof cable entry device, including a housing (25), characterized in that, a boss (16) is provided on one side of the housing (25), an outer end face (20) is provided on one side of the boss (16), a second inner hole (21) is provided inside the boss (16), an upper part (23) is provided inside the second inner hole (21), a first sealing groove (17), a second sealing groove (18), and a third sealing groove (19) are provided inside the upper part (23), a female thread (22) is provided inside the second inner hole (21) on one side of the upper part (23), and the female thread (22) extends only from the outer end face (20) of the boss (16) to the third sealing groove (19), a second step (15) is provided on one side of the second inner hole (21), a bottom part (24) is provided on one side of the second step (15), and a bottom end face (14) is provided on one side of the bottom part (24); a sealing ring (46) is provided inside the second inner hole (21), the material of the sealing ring (46) is made of silica gel and added with metal antioxidants and ultraviolet-resistant agents, the sealing ring (46) includes a front end (10) and a rear end (11), a first inner hole (6) is provided inside the front end (10) and the rear end (11), a first step (1) is provided between the front end (10) and the rear end (11), a front end face (9) is provided on one side of the front end (10), a rear end face (5) is provided on one side of the rear end (11), a first sealing rib (2), a second sealing rib (3), and a third sealing rib (4) are provided on the outside of the rear end (11), the bottom part (24) and the front end (10) are elliptical, and the rear end (11) and the upper part (23) are circular; the first sealing rib (2) is located inside the first sealing groove (17) to form a third sealing joint surface (38), the second sealing rib (3) is located inside the second sealing groove (18) to form a fourth sealing joint surface (39), the third sealing rib (4) is located in the third sealing groove (19) to form a fifth sealing joint surface (40), and a displacement space (35) is provided between the first sealing rib (2) and the first sealing groove (17), between the second sealing rib (3) and the second sealing groove (18), and between the third sealing rib (4) and the third sealing groove (19); a compression nut (43) is provided inside the second inner hole (21) on one side of the sealing ring (46), a gasket (45) is provided between the sealing ring (46) and the compression nut (43), the compression nut (43) includes a top end (26) and a nut (32), a third inner hole (29) is provided inside the top end (26) and the nut (32), an external thread (27) is provided on the outside of the top end (26), a lock prevention end face (28) is provided on one side of the nut (32), a multi-layer corrugated spring (44) is provided on one side of the lock prevention end face (28), and the multi-layer corrugated spring (44) and the lock prevention end face (28) include a plurality of wave crests (30) and wave troughs (31); a cable (42) is inserted into the first inner hole (6), the second inner hole (21), and the third inner hole (29), the front end face (9) and the bottom end face (14) form a first sealing joint surface (36), the first step (1) and the second step (15) form a second sealing joint surface (37), and a sixth sealing joint surface (41) is formed between the sealing ring (46) and the cable (42).

2. A high protection explosion-proof cable entry device according to claim 1, It is characterized in that The hardness of the sealing ring (46) is maintained at 50 to 55 degrees Shore.

3. A sealing method for the high protection explosion-proof cable entry device according to claim 1, It is characterized in that The following steps are involved: (1) After assembling the sealing ring (46) to the inner hole 2 (21) of the boss (16), insert the cable (42) into the inner hole 1 (6) of the sealing ring (46); (2) Place the gasket (45) on the rear end face (5) of the sealing ring (46), and then insert the outer thread (27) of the clamping nut (43) into the inner diameter of the multi-layer wave spring (44). Then screw the outer thread (27) of the clamping nut (43) into the inner thread (22) of the boss (16). Then insert the cable (42) into the inner hole (6) of the clamping nut (43) and into the housing (25). Then fix the torque wrench on the clamping nut. The multilayer wave spring (44) is screwed onto the hexagonal nut (32) of the multilayer wave spring (44) and tightened to the specified torque. At this time, the wave crests (30) and wave troughs (31) at one end of the multilayer wave spring (44) are in contact with the outer end surface of the boss (16), and the wave crests (30) and wave troughs (31) at the other end are in contact with the wave crests (30) and wave troughs (31) of the anti-loosening end surface (28) of the clamping nut (43), and the wave crests (30) of the clamping nut (43) correspond to the wave troughs (31) of the multilayer wave spring (44).

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