Automatic torque device for sample cell

Abstract

The invention provides an automatic torque device for a sample cell, and belongs to the technical field of torque devices. The device comprises a base; the clamping mechanism is arranged on the base; the first driving mechanism is arranged on the base and is used for driving the clamping mechanism to clamp the sample pool; a lifting device; the tightening device is arranged on the lifting device, ascends and descends under the driving of the lifting device, and is used for applying a preset torque value to the sample cell; the tightening device is provided with a torque sensor used for detecting the current torque value. The torque sensor is arranged on the tightening device to detect the current torque value in real time, when it is detected that the current torque value is equal to the set torque value, the tightening device stops working, the consistency of the torque of the sample pool is guaranteed, the phenomena that the torque is different and the torque is too high or too low during manual operation of different operators are avoided, and the working efficiency is improved. The accuracy of the torque of the sample cell is ensured, and the phenomenon of over-high or over-low torque is reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of torque devices, and in particular to an automatic torque device for a sample cell, and more particularly to an automatic torque device suitable for an AUC sample cell. Background Art

[0002] Analytical Ultracentrifugation (AUC) is one of the main technical means for characterizing the properties of biological macromolecules and studying the physical and chemical properties of biomolecules, and is used to analyze sample heterogeneity, the formation of aggregates, and intermolecular interactions, etc. An analytical ultracentrifuge consists of a main body, an optical system, a rotor, and a sample cell, etc., and can monitor in real time the change of solute concentration with time and distance during the sedimentation process of the sample, so as to calculate the molecular properties. The sample cell assembly of an analytical ultracentrifuge mainly consists of a sample cell housing, a central assembly, and a threaded ring. The top area of the sample cell housing is decorated with internal threads, while the outer ring of the threaded ring is decorated with external threads. Generally, it is necessary to manually tighten the threaded ring onto the internal threads. Manual operation is quite dependent on the technical level of the operator, and there may be situations where the torque is too high or too low, which cannot ensure the consistency of the torque. Moreover, manual operation is time-consuming and laborious, and some operators with less strength may not be able to reach the torque value required by the sample. Summary of the Invention

[0003] In view of this, to solve the technical problem in the prior art that when manually tightening the threaded ring onto the internal threads, the consistency of the torque cannot be ensured, the present invention provides an automatic torque device for a sample cell. The manual operation is replaced by a tightening device, and a torque sensor is arranged on the tightening device to detect the current torque value in real time. When it is detected that the current torque value is equal to the set torque value, the tightening device stops working, ensuring the consistency of the torque of the sample cell, avoiding the torque size difference of different operators during manual operation, reducing the phenomenon of too high or too low torque, ensuring the accuracy of the torque of the sample cell, and reducing the phenomenon of too high or too low torque.

[0004] To achieve the above object, the present invention provides the following technical solutions:

[0005] An automatic torque device for a sample cell, comprising:

[0006] A base;

[0007] A clamping mechanism, arranged on the base;

[0008] A first driving mechanism, arranged on the base and used to drive the clamping mechanism to clamp the sample cell;

[0009] A lifting device;

[0010] A tightening device is arranged on the lifting device and is lifted under the drive of the lifting device, and is used to apply a preset torque value to the sample cell;

[0011] A torque sensor for detecting the current torque value is arranged on the tightening device.

[0012] Preferably, the clamping mechanism includes:

[0013] A fixed flange is arranged on the base, and a first hole is formed on the cylindrical surface thereof;

[0014] An outer conical sleeve is sleeved inside the fixed flange, and a second hole is formed on the cylindrical surface thereof;

[0015] A cam block is arranged on the second hole and can slide along the second hole. The cam block passes through the first hole and is used to drive the outer conical sleeve to move up and down;

[0016] An inner conical sleeve is sleeved inside the outer conical sleeve, and the inner and outer surfaces thereof have a certain taper and the taper increases step by step from bottom to top.

[0017] Preferably, the first driving mechanism includes a clamping motor and a clamping speed reducer arranged on the base. The clamping motor is connected to the clamping speed reducer, and the clamping speed reducer is connected to the clamping mechanism.

[0018] Preferably, the lifting device includes:

[0019] A support frame is arranged on the base;

[0020] A sliding table is slidably connected to the support frame;

[0021] A second driving structure is arranged on the support frame and is used to drive the sliding table to slide along the extending direction of the support frame.

[0022] Preferably, the second driving structure includes a lifting motor, a coupling and a lead screw mechanism. The lifting motor is connected to the lead screw mechanism through the coupling, and the lead screw mechanism is connected to the sliding table and is used to drive the sliding table to move up and down.

[0023] Preferably, the tightening device further includes:

[0024] A third driving mechanism is arranged on the lifting device;

[0025] A tightening head is connected to the output end of the third driving mechanism;

[0026] The torque sensor is arranged between the third driving mechanism and the tightening head.

[0027] Preferably, the third driving mechanism includes a tightening motor and a tightening speed reducer, which are connected together, and the tightening speed reducer is used to apply torque to the tightening head.

[0028] Preferably, the tightening head includes:

[0029] A fourth flange, connected to the output end of the tightening speed reducer;

[0030] A tightening block, disposed in the cavity of the fourth flange,

[0031] A tightening piece, disposed at the bottom end of the tightening block and extending out of the bottom end of the cavity of the fourth flange, for applying torque to the sample cell.

[0032] Preferably, it further includes:

[0033] A spring, disposed in the inner cavity of the tightening block, for keeping the tightening piece extending outwards.

[0034] Preferably, the sample cell includes a housing and an external thread ring disposed inside the housing;

[0035] A notch is formed on the external thread ring;

[0036] The tightening piece on the tightening device is used to be clamped into the notch and can slide along the notch.

[0037] The present invention has the following beneficial effects compared with the prior art:

[0038] (1) High precision: The automatic torque device provided by the present invention can better ensure the accuracy of the torque of the sample cell, reducing the phenomenon of excessive or too low torque.

[0039] (2) Consistency: The automatic torque device provided by the present invention can ensure the consistency of the torque of the sample cell, avoiding the difference in torque magnitude during manual operation by different operators.

[0040] (3) Time and labor saving: The operator only needs to place the assembled sample cell in the fixture, and the application of the torque of the sample cell is completely automatically realized, effectively reducing the difficulty and workload of manual operation and saving a large amount of manpower and time.

[0041] Other advantages of the present invention will be described in detail in combination with the specific structure in the following detailed description of the specific implementation manner. Brief Description of the Drawings

[0042] Figure 1 is the overall structural schematic diagram of the present invention;

[0043] Figure 2 is the schematic diagram of the clamping mechanism of the present invention;

[0044] Figure 3 It is a schematic diagram of the lifting mechanism of the present invention;

[0045] Figure 4 It is a schematic diagram of the tightening mechanism of the present invention;

[0046] Figure 5 It is a schematic diagram of the fixture of the present invention;

[0047] Figure 6 It is an exploded view of the fixture of the present invention;

[0048] Figure 7 It is a schematic diagram of the sample cell of the present invention;

[0049] Figure 8 It is a schematic diagram of the tightening head of the present invention;

[0050] Figure 9 It is a partial cross-sectional view of the present invention;

[0051] Figure 10 It is another implementation manner of the present utility model;

[0052] In the figure, 1 is the base; 11 is the first driving mechanism; 12 is the clamping motor; 13 is the clamping motor mounting plate; 14 is the clamping reducer; 15 is the clamping reducer mounting plate; 16 is the clamping mechanism; 161 is the fixed flange; 162 is the outer conical sleeve; 163 is the cam block; 164 is the inner conical sleeve; 2 is the lifting device; 21 is the support frame; 22 is the lifting motor; 23 is the lifting motor mounting plate; 24 is the coupling; 25 is the lead screw mechanism; 26 is the sliding table; 3 is the tightening device; 31 is the tightening motor; 32 is the tightening motor mounting plate; 33 is the tightening reducer; 34 is the first flange; 35 is the second flange; 36 is the torque sensor; 37 is the third flange; 38 is the fourth flange; 39 is the tightening head; 391 is the tightening piece; 392 is the tightening block; 393 is the spring; 4 is the sample cell; 41 is the outer shell; 42 is the external thread ring; 421 is the notch. 5 is the in-situ sensor; 51 is the sensor mounting bracket. Detailed implementation manners

[0053] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0054] In the description of the present invention, it should be noted that the orientation or positional relationship indicated by the terms "upper", "lower", "inner", "outer", "top / bottom end", etc. is based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, it should not be construed as a limitation to the present invention. In addition, the terms "first" and "second" are only used for descriptive purposes and cannot be construed as indicating or implying relative importance.

[0055] In the description of the present invention, it should be noted that unless otherwise clearly specified and defined, the terms "mounted", "provided with", "sheathed / connected", "connected", etc. should be understood in a broad sense. For example, "connected" can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0056] As Figure 1 shown, the present invention provides an automatic torque device for a sample cell, including:

[0057] A base 1, serving as the basic structure for supporting the entire device.

[0058] A clamping mechanism 16, arranged on the base 1 and used for clamping the sample cell 4.

[0059] A first driving mechanism 11, arranged on the base 1 and used for driving the clamping mechanism 16 to clamp the sample cell 4.

[0060] A lifting device 2, preferably arranged on the base 1 and used for driving the following tightening device 3 to lift.

[0061] A tightening device 3, arranged on the lifting device 2 and lifted under the drive of the lifting device 2, and used for applying a preset torque value to the sample cell 4.

[0062] A torque sensor 36 for detecting the current torque value is arranged on the tightening device 3.

[0063] In the above-described automatic torque device for the sample cell 4 provided by the present invention, by directly connecting the torque sensor 36 in series to the transmission chain of the tightening device 3, the torque value applied to the external thread ring 42 of the sample cell 4 is detected in real time. The detected torque value is compared with a preset target value, and the start and stop of the tightening device 3 are controlled to ensure that the torque accurately reaches the set threshold, guaranteeing the consistency of the torque of the sample cell 4. Full-automatic closed-loop control and automated operation are achieved. On the premise of ensuring torque accuracy and consistency, the difficulty and workload of manual operation are effectively reduced, and a large amount of manpower and time are saved.

[0064] As Figures 4 - 6 shown, in the present invention, the clamping mechanism 16 includes:

[0065] A fixed flange 161, which is arranged on the base 1, and has a first hole on its cylindrical surface.

[0066] An outer cone sleeve 162, which is sleeved inside the fixed flange 161. Its cylindrical surface has a second hole, and this second hole is used to install the following cam block 163, so that the cam block 163 slides along the contour of the second hole, realizing the up and down movement of the outer cone sleeve 162 driven by the rotation of the cam block 163.

[0067] A cam block 163, which is arranged on the second hole and can slide along the second hole. The cam block 163 passes through the first hole and is used to drive the outer cone sleeve 162 to move up and down.

[0068] An inner cone sleeve 164, which is sleeved inside the outer cone sleeve 162. Its inner and outer surfaces have a certain taper and the taper increases gradually from bottom to top.

[0069] It should be noted that the inner wall of the outer cone sleeve 162 has no taper to avoid local stress concentration and protect the surface finish of the outer shell 41 of the sample cell 4. The fixed flange 161, the outer cone sleeve 162 and the inner cone sleeve 164 are preferably coaxially arranged to ensure uniform distribution of the clamping force and eliminate the risk of tilting or offset of the sample cell 4 caused by eccentric clamping. The sample cell 4 is placed inside the inner cone sleeve 164. In the initial state, there is a gap between the inner cone sleeve 164 and the inner wall of the outer cone sleeve 162. The first driving mechanism 11 drives the cam block 163 to rotate along the contour of the second hole, causing the outer cone sleeve 162 to move upward during the rotation of the cam block 163, so that the inner wall of the outer cone sleeve 162 presses against the outer surface of the inner cone sleeve 164. Due to the taper design, the inner cone sleeve 164 generates radial elastic deformation and will be gradually clamped until the outer shell 41 of the sample cell 4 is clamped. When the first driving mechanism 11 rotates in reverse, it drives the cam block 163 to rotate in reverse, the outer cone sleeve 162 moves under the action of the cam block 163, and the inner cone sleeve 164 elastically recovers, releasing the clamping force on the sample cell 4.

[0070] The above technical solution of the present invention can adaptively design without manual intervention for the clamping force, reducing the operation complexity. By replacing the inner tapered sleeves 164 with different tapers, various specifications of sample cells can be adapted.

[0071] As Figure 2 shown, in the present invention, the first driving mechanism 11 includes a clamping motor 12 and a clamping speed reducer 14 provided on the base 1. The clamping motor 12 and the clamping speed reducer 14 are connected, and the clamping speed reducer 14 and the clamping mechanism 16 are connected. Preferably, the following installation method is adopted:

[0072] The clamping motor 12 is connected to the clamping motor mounting plate 13. The clamping motor mounting plate 13 is connected to the following support frame 21. The support frame 21 is connected to the base 1. The clamping speed reducer 14 is connected to the clamping speed reducer mounting plate 15. The clamping speed reducer mounting plate 15 is connected to the base 1. The clamping speed reducer 14 is connected to the keyway in the cam block 163. The rotational movement of the clamping motor 12 is converted into the up and down movement of the outer tapered sleeve 162 through the cam block 163. When the outer tapered sleeve 162 moves upward, the sample cell 4 is clamped. When the outer tapered sleeve 162 moves downward, the sample cell 4 is released.

[0073] As Figure 3 shown, in the present invention, the lifting device 2 includes:

[0074] A support frame 21, provided on the base 1, serving as the rigid support matrix of the entire lifting device 2.

[0075] A sliding table 26, slidably connected to the support frame 21, preferably slidably connected to the guide rail provided on the support frame 21.

[0076] A second driving structure, provided on the support frame 21, for driving the sliding table 26 to slide along the extending direction of the support frame 21. Preferably, the rotational movement of the second driving structure is converted into a linear displacement.

[0077] The lifting device 2 preferably adopts the following installation method:

[0078] The support frame 21 is connected to the base 1. The lifting motor mounting plate 23 is connected to the support frame 21. The lifting motor 22 is mounted on the lifting motor mounting plate 23. At the same time, the lifting motor 22 is connected to the lead screw mechanism 25 through a coupling 24. The sliding table 26 is slidably connected to the guide rail provided on the support frame 21. At the same time, the sliding table 26 is connected to the slider and nut in the lead screw mechanism 25. The rotational movement of the lifting motor 22 is converted into the up and down movement of the sliding table 26 through the lead screw mechanism 25. And the tightening device 3 is just connected to the sliding table 26. Therefore, the tightening device 3 will move up and down with the sliding table 26.

[0079] The above-mentioned lifting device 2 of the present invention realizes high-precision positioning, efficient operation and strong load capacity of the tightening device 3 through the precise transmission of the lead screw-guide rail and the direct drive control of the motor, solves the problems of low efficiency, large error and poor compatibility of the traditional manual or semi-automatic lifting method, and provides a reliable guarantee for the automatic torque application of the AUC sample cell.

[0080] In the present invention, the second driving structure includes a lifting motor 22, a coupling 24 and a lead screw mechanism 25. The lifting motor 22 is connected to the lead screw mechanism 25 through the coupling 24. The lead screw mechanism 25 is connected to the slide table 26 and is used to drive the slide table 26 to move up and down.

[0081] As Figure 4 shown, in the present invention, the tightening device 3 further includes:

[0082] A third driving mechanism, arranged on the lifting device 2;

[0083] A tightening head 39, connected to the output end of the third driving mechanism;

[0084] The torque sensor 36 is arranged between the third driving mechanism and the tightening head 39.

[0085] In the present invention, the third driving mechanism includes a tightening motor 31 and a tightening reducer 33. The tightening motor 31 and the tightening reducer 33 are connected together. The tightening reducer 33 is used to apply torque to the tightening head 39.

[0086] The tightening device 3 preferably adopts the following installation method:

[0087] The tightening motor 31 and the tightening reducer 33 are connected together. The torque of the tightening motor 31 can be amplified through the tightening reducer 33 to reach the torque value required for the test. The tightening motor 31 and the tightening reducer 33 are respectively installed on two tightening motor mounting plates. The tightening mounting plate is connected to the slide table 26. A first flange 34 is connected below the tightening reducer 33. The first flange 34 is connected to a second flange 35. The second flange 35 is connected to the upper end of the torque sensor 36. The lower end of the torque sensor 36 is connected to a third flange 37. The third flange 37 is connected to a fourth flange 38. The tightening head 39 is installed in the cavity of the fourth flange 38. When the tightening motor 31 rotates, the tightening head 39 also rotates accordingly.

[0088] As Figures 8 - 9 shown, in the present invention, the tightening head 39 includes:

[0089] A fourth flange 38, connected to the output end of the tightening reducer 33;

[0090] The tightening block 392 is disposed in the cavity of the fourth flange 38.

[0091] The tightening piece 391 is disposed at the bottom end of the tightening block 392 and extends out of the bottom end of the cavity of the fourth flange 38 , and is used to apply torque to the sample pool 4 .

[0092] The present invention also includes:

[0093] The spring 393 is disposed in the inner cavity of the tightening block 392 and is used to keep the tightening piece 391 extending outward.

[0094] The tightening head 39 is preferably installed in the following manner:

[0095] The tightening block 392 is installed in the cavity of the fourth flange 38, the upper end of the spring 393 is sleeved on the lower cylinder of the third flange 37, and the lower end of the spring 393 contacts the lower surface of the inner cavity of the tightening block 392. In a static state, the entire tightening head 39 remains in an extended state under the action of the spring 393 to ensure that its initial position is stable.

[0096] like Figure 7 As shown, in the present invention, the sample pool 4 includes a housing 41 and an external threaded ring 42 disposed in the housing (the external threaded ring 42 is connected to the internal threaded ring inside the housing 41);

[0097] The external thread ring 42 is provided with a notch 421;

[0098] The tightening piece 391 on the tightening device 3 is used to be snapped into the notch 421 and can slide along the notch.

[0099] When the lifting device 2 drives the tightening head 39 to descend to the surface of the outer thread ring of the sample cell, the spring 393 is compressed and shrinks, allowing the tightening head 39 to retract under pressure; when the tightening motor 31 rotates to the rectangular notch position of the thread ring, the spring 393 releases its elastic force, pushing the tightening piece 391 to quickly snap into the notch to achieve precise engagement. The spring provides a flexible buffer when the tightening head 39 contacts the thread ring to avoid damage to the components caused by hard collision.

[0100] During the torque application process, the elastic deformation of the spring 393 can compensate for the slight displacement between the tightening plate 391 and the notch, ensuring that the tightening head 39 is always in close contact with the threaded ring, avoiding slippage or misalignment, and maintaining a constant contact pressure.

[0101] The method of use of the present invention is as follows:

[0102] In use, first manually place the sample cell in the clamping mechanism 16, and then the clamping motor 12 rotates to drive the outer tapered sleeve 162 to move upward. Since the inner tapered sleeve 164 has a taper that gradually increases from bottom to top and has a certain elasticity, the inner tapered sleeve 164 will be clamped, and at the same time, the sample cell 4 inside the inner tapered sleeve 164 will also be clamped. After the sample cell 4 is clamped, the lifting motor 22 starts to work to drive the tightening device 3 to descend as a whole. When the tightening piece 391 in the tightening device 3 contacts the upper surface of the external thread ring 42 on the sample cell, as the tightening head rotates, the tightening piece 391 slides on the external thread ring 42. When it slides to the corresponding notch 421, the tightening head 39 will slowly extend in under the action of the extrusion force. At the same time, the tightening motor 31 rotates slowly. When passing through the rectangular notch 421 in the external thread ring, the tightening piece 391 on the tightening head 39 is clamped into the rectangular notch 421 in the external thread ring under the action of the spring 393. At the same time, the lifting motor 22 stops working, and then the tightening motor 31 continues to apply torque. The torque sensor 36 is used to detect the current torque value. When the detected current torque value is equal to the set torque value, the tightening motor 31 stops working, and at the same time, the clamping motor 12 stops working, and the whole device completes the process of automatically applying torque to the sample cell 4.

[0103] As Figure 10 shown, this is another embodiment of the present invention, which is basically the same as the above embodiment. Since the tightening head 39 is not integral, the requirement for the spring 393 is relatively high, the actual operation is not very stable, and the later maintenance is not convenient. In this specific embodiment, it is changed to be integral, the spring 393 is cancelled, and an in-situ sensor 5 is added (by detecting the position signal of the scale line, feeding back whether the sample cell is in the preset "in-situ" state, and providing a trigger condition for subsequent automated operations such as sample addition and detection). The direction of the tightening head 39 is aligned with the notch 421, and it is directly stuck in the notch 421 through the lifting device 2, and then tightened. The whole tightening head is connected to the third flange 37. When placing the sample cell 4, the sample cell 4 is aligned with the in-situ scale line on the fixture mechanism 16, and the in-situ scale line is aligned with the in-situ sensor 5.

[0104] The above; only the preferred specific embodiments of the present invention; but the protection scope of the present invention is not limited thereto; any person skilled in the art within the technical scope disclosed by the present invention; according to the technical solution of the present invention and its improvement concept, making equivalent substitutions or changes; should be covered by the protection scope of the present invention.

Claims

1. An automatic torque device for a sample cell, characterized in that, Comprising: Base; Clamping mechanism, arranged on the base; First driving mechanism, arranged on the base and used to drive the clamping mechanism to clamp the sample cell; Lifting device; Tightening device, arranged on the lifting device and lifted under the drive of the lifting device, used to apply a preset torque value to the sample cell; A torque sensor for detecting the current torque value is arranged on the tightening device.

2. The automatic torque device for a sample cell according to claim 1, characterized in that, The clamping mechanism includes: Fixed flange, arranged on the base, with a first hole opened on its cylindrical surface; Outer conical sleeve, sleeved inside the fixed flange, with a second hole on its cylindrical surface; Cam block, arranged on the second hole, capable of sliding along the second hole, and the cam block passes through the first hole, used to drive the outer conical sleeve to move up and down; Inner conical sleeve, sleeved inside the outer conical sleeve, with a certain taper on its inner and outer surfaces and the taper increasing gradually from bottom to top.

3. The automatic torque device for a sample cell according to claim 1, wherein, The first driving mechanism includes a clamping motor and a clamping speed reducer arranged on the base, the clamping motor is connected to the clamping speed reducer, and the clamping speed reducer is connected to the clamping mechanism.

4. An automatic torque device for a sample cell according to claim 1, characterized in that, The lifting device includes: Support frame, arranged on the base; Slide table, slidably connected to the support frame; Second driving structure, arranged on the support frame, used to drive the slide table to slide along the extending direction of the support frame.

5. The automatic torque device for a sample cell according to claim 4, wherein The second driving structure includes a lifting motor, a coupling and a lead screw mechanism, the lifting motor is connected to the lead screw mechanism through the coupling, and the lead screw mechanism is connected to the slide table, used to drive the slide table to move up and down.

6. An automatic torque device for a sample cell according to claim 1, characterized in that, The tightening device further includes: Third driving mechanism, arranged on the lifting device; Tightening head, connected to the output end of the third driving mechanism; The torque sensor is arranged between the third driving mechanism and the tightening head.

7. An automatic torque device for a sample cell according to claim 6, characterized in that, The third driving mechanism includes a tightening motor and a tightening speed reducer, the tightening motor is connected to the tightening speed reducer, and the tightening speed reducer is used to apply torque to the tightening head.

8. An automatic torque device for a sample cell according to claim 7, characterized in that, The tightening head includes: Fourth flange, connected to the output end of the tightening speed reducer; Tightening block, arranged in the cavity of the fourth flange, Tightening piece, arranged at the bottom end of the tightening block and extending out of the bottom end of the cavity of the fourth flange, used to apply torque to the sample cell.

9. The automatic torque device for a sample cell according to claim 8, characterized in that, Also included: Spring, arranged in the inner cavity of the tightening block, used to keep the tightening piece extending outwards.

10. An automatic torque device for a sample cell according to any one of claims 1-9, characterized in that, The sample cell includes a housing and an external thread ring arranged inside the housing; A notch is opened on the external thread ring; The tightening piece on the tightening device is used to be clamped into the notch and can slide along the notch.

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