Shape memory alloy locking device

Abstract

The invention relates to a shape memory alloy locking device, belongs to the field of mechanical locks, and solves the problems that a traditional shape memory alloy locking device is numerous and jumbled in structure and cannot be repeatedly used. The locking device comprises an upper shell and a lower shell, the upper shell and the lower shell are assembled together to define an internal working space, a friction plate is rotatably arranged in the working space, the locking device further comprises a limiting plate and a limiting plate control piece, the limiting plate is arranged between the friction plate and the upper shell, and the limiting plate control piece is arranged between the friction plate and the upper shell. The limiting plate control piece is made of shape memory alloy, the shape memory alloy stretches out and draws back to control the limiting plate to move up and down, and therefore the friction plate is unlocked and locked through the limiting plate. The locking device is simple and compact in structure and can be repeatedly used.

Description

Technical field:

[0001] The invention belongs to the field of mechanical locks, and in particular relates to a shape memory alloy locking device. Background technology:

[0002] Locking devices are often needed in aerospace vehicles. For example, locking devices are used in steering gears or servo mechanisms to achieve self-locking functions to prevent air rudders or engine nozzles from colliding due to bumps and swings on the road during transportation; locking devices are used in folding rudders to achieve the rudder surface deployment and locking functions; and locking devices are used in separation mechanisms to achieve the locking function before the equipment is separated.

[0003] At present, the commonly used locking device driving methods for aerospace vehicles generally include electromagnetic force, gunpowder impact force and shape memory alloy phase change effect. The gunpowder locking device mainly uses the impact force generated by the combustion of gunpowder as the driving force. In actual engineering applications, the main disadvantages are that it is highly dangerous and cannot be used repeatedly; the electromagnetic locking device is mainly composed of electromagnets, springs, wire package components, locking mechanisms, etc., and its structure is complex, prone to demagnetization, and prone to problems such as burning the wire package components due to heat after long-term operation; the driving material in the shape memory alloy locking device is safe and simple in structure, which overcomes the shortcomings of the above two devices.

[0004] However, shape memory alloy materials also have limitations as the driving force of the locking device. The most prominent one is that the deformation caused by the shape memory phase change is relatively small. Therefore, some solutions use multiple groups of shape memory alloy materials in series to increase the displacement of the locking device, which makes the overall structure of the locking device larger. Summary of the invention:

[0005] The invention provides a shape memory alloy locking device, which has environmentally friendly driving force, simple structure, can be repeatedly used and is compact, thus overcoming the problem that the traditional locking device has a complicated structure and cannot be repeatedly used.

[0006] A shape memory alloy locking device comprises an upper shell and a lower shell, wherein the upper shell and the lower shell are assembled together to define an internal working space, and a friction plate is rotatably arranged in the working space. The locking device also comprises a limit plate and a limit plate control component, wherein the limit plate is arranged between the friction plate and the upper shell, and the limit plate control component is made of shape memory alloy. The extension and contraction of the shape memory alloy controls the up and down movement of the limit plate, thereby realizing the unlocking and locking of the friction plate by the limit plate.

[0007] Furthermore, the limit plate control component is an axial spring assembly, and the axial spring assembly includes a group of axial springs made of shape memory alloy, and the axial springs are vertically arranged in the working space.

[0008] Furthermore, the axial spring assembly has four axial springs, and the upper ends and lower ends of the four axial springs are respectively in the same horizontal plane and are evenly distributed in the circumferential direction.

[0009] Furthermore, one end of the axial spring is connected to the upper shell, and the other end of the axial spring is connected to the upper surface of the limiting plate.

[0010] Furthermore, the axial spring assembly realizes the pressing of the friction plate by the limit plate through the axial springs all entering the first compression state.

[0011] Furthermore, the axial spring assembly realizes a dynamic separation process of the limit plate from the friction plate by energizing the shape memory alloy.

[0012] Furthermore, the axial spring assembly realizes a static separation state of the limit plate from the friction plate by the axial springs entering a second compression state, and the compression degree of the axial springs in the second compression state is greater than the compression degree of the axial springs in the first compression state.

[0013] Furthermore, the upper shell includes an upper shell body and four downwardly extending inverted L-shaped support columns, the support columns include a transverse column and a vertical column, the transverse column and the vertical column are perpendicular to each other, corresponding to the two sides of the inverted L shape; the support columns are evenly distributed along the circumference of the edge of the upper shell body, and the height of the inner surface of the vertical column of the support column limits the height of the working space.

[0014] Furthermore, a mounting hole is provided on the transverse column of the support column, and the axial springs in the axial spring assembly are respectively installed in the mounting holes.

[0015] Furthermore, an upper friction ring is fixedly connected to the lower surface of the limiting plate.

[0016] Furthermore, the locking device also includes a radial spring assembly, which includes a group of radial springs made of shape memory alloy. The radial springs are radially arranged in a horizontal plane above the friction plate, one end of the radial spring is connected to the side wall of the working space, and the other end of the radial spring is against the limit plate.

[0017] Furthermore, a blind hole is provided on the inner surface of the column of the support column, and the radial spring assembly is installed in the blind hole.

[0018] Furthermore, there are four radial springs in the radial spring assembly, and the radial spring assembly also includes four pins, the pin heads of the pins are connected to the inner ends of the radial springs, the pin bodies of the pins extend inward along the center lines of the radial springs, and the radial springs are pressed against the limit plates through the pins.

[0019] Furthermore, the pin in the radial spring assembly is a T-shaped pin, and the radial spring assembly also includes two screws; lateral holes are opened on the two side surfaces of the column of the support column, the two lateral holes of the same column are connected and intersect with the blind hole on the column, and the two screws are inserted into the same column oppositely through the two lateral holes, the nail head of the T-shaped pin is stuck by the outer surfaces of the two screws, and the nail body of the pin passes through the gap between the ends of the two screws.

[0020] Compared with the prior art, the present invention can achieve at least one of the following beneficial effects:

[0021] (1) The present application uses a shape memory alloy combined with a friction plate to achieve locking. Locking can be achieved by only pressing the friction plate with a driving force. Compared with the combination of a shape memory alloy as a latch (pin puller) and a rotating part, there is no need for excessive forward and backward displacement between the shape memory alloy as a latch (pin puller) and the rotating part, thereby reducing the overall volume of the locking device.

[0022] (2) The shape memory alloy of the present application is made into a spring, which can simultaneously utilize the compressible characteristics of the spring itself and the shrinkable characteristics of the shape memory alloy when energized. When switching from the locked state to the unlocked state, the spring is further compressed from the first compressed state to the second compressed state by utilizing the contraction force of the shape memory alloy after energization, wherein only the small compression displacement difference corresponding to the two compressed states needs to be overcome, unlike the traditional spring locking device, which needs to overcome the large displacement of the spring in the stretched-natural-compressed state, thereby further reducing the volume of the locking device, which is beneficial to reducing the envelope of the aircraft shape, and thus is beneficial to optimizing the aerodynamic shape of the aircraft.

[0023] (3) The outer shell in the present application is realized by setting a support column. Compared with the traditional fully enclosed shell, the weight of the locking device is significantly reduced while ensuring the accommodation of the mounting hole, which is beneficial to improving the maneuverability and speed of the aircraft.

[0024] (4) The present application also includes a radial spring assembly, in which the pin can be pressed against the bottom of the limit plate in the unlocked state, supporting the limit plate to balance the compressive force applied to the limit plate by the spring in the second compressed state, thereby reducing the possibility of the limit plate falling and interfering with the friction plate that is running freely, thereby ensuring the working state of such a compact locking device; at the same time, due to the supporting effect of the radial spring assembly, the axial spring assembly can be powered off after the locking device enters the unlocked state, thereby achieving long-term power off in the unlocked state, reducing the impact of unexpected power outages or current instability, and reducing energy consumption.

[0025] In the present invention, the above-mentioned technical solutions can also be combined with each other to achieve more preferred combination solutions. Other features and advantages of the present invention will be described in the following content, and some advantages can be obvious from the description or understood by practicing the present invention. The purpose and other advantages of the present invention can be realized and obtained through the contents particularly pointed out in the text and the drawings. Description of the drawings:

[0026] Figure 1 is a schematic diagram of the three-dimensional structure of the shape memory alloy locking device in a locked state;

[0027] Figure 2 is a bottom view of the shape memory alloy locking device in a locked state;

[0028] Figure 3 yes Figure 2 AA section view;

[0029] Figure 4 is a bottom view of the shape memory alloy locking device in an unlocked state;

[0030] Figure 5 yes Figure 4 AA section view;

[0031] Figure 6 It is a structural schematic diagram of the upper shell;

[0032] Figure 7 is a schematic diagram of the structure of the lower housing assembly;

[0033] Figure 8 1 is a schematic diagram of the structure of the limit plate assembly;

[0034] Fig. 9 It is a schematic diagram of the structure of the friction plate;

[0035] Fig.10 yes Figure 1 Schematic cross-section of .

[0036] Reference numerals:

[0037] 1-upper housing, 2-radial spring assembly, 3-axial spring assembly, 4-lower housing assembly, 5-friction plate, 6-limiting plate assembly, 7-pin, 8-lower housing, 9-lower friction ring, 10-limiting plate, 11-upper friction ring, 12-support column, 13-transmission hole, 14-blind hole, 15-mounting hole, 16-lateral hole. Specific implementation method:

[0038] A shape memory alloy locking device, such as Figure 1-5As shown, it includes an upper shell 1 and a lower shell 8. After the upper shell 1 and the lower shell 8 are assembled, a working space is formed in the middle. A limit plate 10, a friction plate 5 and a limit plate control member are arranged in the working space. The locking device controls the movement of the limit plate 10 through the limit plate control member, which is specifically reflected in the limit plate 10 pressing and disengaging against the friction plate 5 to achieve locking and unlocking of the friction plate 5. The external interface of the friction plate 5 is connected to the transmission extension part of the external device (such as the tail shaft of the motor). The locking and unlocking of the friction plate 5 is to limit and release the shaking of the transmission part and the transmission extension part when the external device stops working. The following is a specific description through an embodiment in conjunction with the accompanying drawings.

[0039] Embodiment 1:

[0040] like Figure 3 , Figure 5 , Fig. 9 As shown, the friction plate 5 includes a friction plate body and a protruding portion extending outward, and the protruding portion is provided with a transmission hole 13 with an outer circle and an inner square as an external output interface.

[0041] Working principle of the friction plate: the friction plate 5 is the locking object of the locking device, and the friction plate 5 is connected to the external equipment. When the friction plate 5 is locked, the friction plate 5 cannot move freely, and the external equipment connected to it is also indirectly restricted; when the friction plate 5 is unlocked, the friction plate 5 can move freely, and the external equipment connected to it can also rotate freely accordingly.

[0042] like Figure 3 and 5 As shown, the state of the friction plate 5 is directly limited by the limit plate 10 of the locking device. The limit plate 10 is comparable in size to the friction plate body. The thickness and radial dimensions of the two are set according to the locking torque required for the external device. They are slightly smaller than the radial dimensions of the working space in the radial direction, making the radial structure of the locking device compact.

[0043] In order to make the axial dimension of the locking device compact, a gap is set between the lower surface of the friction plate 5 and the lower shell 8, so that the friction plate 5 is not restricted by the upper surface of the lower shell 8 when it rotates freely; above the friction plate 5 in the working space is the activity space of the limit plate 10 and the limit plate control component, the limit plate control component is the axial spring assembly 3, the axial spring assembly is a group of axially arranged axial springs, the material of the axial springs is shape memory alloy, the sizes of the axial springs are the same and they are flush up and down, the upper end of the axial spring is connected to the upper shell, and the lower end is connected to the limit plate.

[0044] The axial spring assembly 3 realizes unlocking and locking of the friction plate 5 by controlling the up and down movement of the limit plate 10. In the locked state, the axial spring is in a first compression state, which causes the axial spring to press the limit plate 10 and the friction plate 5 under the action of the first preload force, and the friction plate 5 and its transmission hole 13 are fixed by the friction force between the two, generating a locking torque.

[0045] When the external device needs to work, the locking-unlocking operation is started: the axial spring assembly 3 is powered on, and the shape memory alloy material is energized and heated to generate an internal contraction force, which overcomes the first preload force to generate an upward combined force, causing each axial spring to further retract, and the axial spring assembly 3 drives the limit plate 10 to move toward the upper shell 1. When the limit plate 10 leaves the friction plate 5 for a certain distance, the further retraction of the axial spring is limited by cutting off the current in the shape memory alloy. At this time, the axial spring enters the second compression state, and the limit plate 10 stops moving.

[0046] Furthermore, in order to keep the limiting plate 10 at a corresponding position, that is, to keep the axial spring in the second compressed state, a radial spring assembly 2 is also provided in the radial direction of the working space.

[0047] The radial spring assembly 2 is arranged on the plane above the friction plate 5, so that the lower surface of the radial spring assembly is adjacent to the upper surface of the friction plate 5 but does not contact each other. The radial spring assembly 2 is a group of radial springs made of shape memory alloy with the same size; in order to further reduce the axial size, the radial spring assembly 2 also includes a group of pins 7, the pins 7 are T-shaped pins, the pin body diameter of the T-shaped pins is smaller than the middle diameter of the radial spring, and the distance that the limit plate 10 moves upward is greater than the diameter of the pin 7. One end of the radial spring is connected to the side of the housing, and the other end is connected to the pin head of the pin 7.

[0048] In the locked state, the radial spring is in a pre-compressed state, and the pin 7 also shrinks, and the free end of the pin 7 just contacts the outer edge of the limit plate 10; when locked and unlocked, the axial spring assembly 3 shrinks upward due to the power supply, and the limit plate 10 moves upward and slowly staggers with the free end of the pin 7; when the free end of the pin 7 is free, the preload force of the radial spring is released, thereby pushing the pin 7 to move toward the center, and the axial spring also enters the second compressed state and stops moving. At this time, each pin 7 supports the limit plate 10 at the same time, achieving a balance of the second preload force and entering the unlocked state.

[0049] like Figure 8As shown, in order to prevent the limit plate 10 itself from being worn, an upper friction ring 11 is fixedly arranged on its lower surface. The upper friction ring 11 is made of a material with a high friction coefficient and good wear resistance, such as synthetic rubber, to improve the friction coefficient and wear resistance between the limit plate 10 and the upper surface of the friction plate 5. The present invention refers to the combination of the upper friction ring 11 and the limit plate 10 as a limit plate assembly 6. The axial spring, radial spring, and pin can be set in four respectively, and the four axial springs are evenly distributed in the circumference of the working space, and the four radial springs are evenly distributed in the circumference of the working space, and the four pins extend inward along the center lines of the four radial springs respectively.

[0050] Figure 1-2 , Figure 4 , Figure 6-7 As shown, the upper shell 1 and the lower shell assembly 4 can be fixed by threads. In order to reduce the weight of the shell, as shown in FIG. Figure 6 As shown, the upper shell 1 includes an upper shell body and four support columns 12 extending downward, the support columns 12 include a horizontal column and a vertical column, the two are perpendicular to each other and form an inverted L shape, the four support columns 12 are evenly arranged along the circumference of the edge of the upper shell, and the horizontal column points from the edge to the shell center. The lower surface of the vertical column is against the upper surface of the lower shell 8, and the height of the vertical column defines the height of the working space.

[0051] A mounting hole 15 is provided on the upper surface of the horizontal column of the support column 12, a blind hole 14 is provided on the inner surface of the column of the support column 12, and a lateral hole 16 is provided on the side surface of the column. The lateral hole 16 is communicated with the blind hole 14, and the lateral holes on each column can be two oppositely arranged.

[0052] In order to prevent the axial spring from shaking, the axial spring assembly 3 is installed in a group of mounting holes 15 in the vertical direction of the upper shell 1, one end of the axial spring is fixed to the bottom of the mounting hole 15, and the other end is fixed to the upper surface of the limit plate assembly 6.

[0053] like Fig.10 As shown, in order to prevent the radial spring from shaking, the radial spring assembly 2 is installed in a group of blind holes 14 in the radial direction of the upper shell, one end of the radial spring is fixed to the bottom of the blind hole 14, and the other end is fixed to the nail head of the pin 7, and the nail body of the T-shaped pin is against the limit plate assembly 6.

[0054] The lateral holes 16 beside the blind hole 14 are provided with screws, and the pin 7 is lightly clamped by the two screws and the nail head is clamped, thereby preventing the radial pin 7 from coming out of the blind hole 14 .

[0055] In the unlocked state, when it is necessary to lock again, the unlocking-locking operation is started: the radial spring assembly 2 is energized, the radial springs of the radial spring assembly 2 are all retracted, and the radial spring drives the pin 7 to move in the radial direction away from the shell center; when the pin 7 is no longer in contact with the limit plate assembly 6, the limit plate assembly 6 moves downward rapidly under the action of the second preload force of the axial spring until the friction plate 5 is pressed under the action of the first preload force of the axial spring; at this time, it enters the locked state, and the limit plate assembly 6 no longer moves. At this time, the radial spring assembly 2 is de-energized, and the contraction force of the shape memory alloy caused by electricity and heating disappears, the preload force in the radial spring is released, and the pin 7 in the radial spring assembly 2 again presses against the outer edge of the limit plate assembly 6.

[0056] In this way, repeated locking and unlocking are achieved. The invention is small in size, can be repeatedly unlocked and locked, and uses the friction between the moving plate assembly (friction plate and related) and the static plate assembly (limit plate and related) as the locking torque. Even if it cannot be unlocked, it only adds additional load torque and will not cause mechanical locking. After unlocking or locking, it does not need to be powered on all the time to maintain the unlocked or locked state, and the power consumption is low.

[0057] Embodiment 2:

[0058] When the locking torque required by the external device is relatively large, the technical solution corresponding to the second embodiment is adopted.

[0059] First, each axial spring in the axial spring assembly 3 is replaced with a spring with a larger preload force. Because the number of turns, wire diameter, middle diameter, pitch and other parameters of the radial spring and the axial spring can be designed according to the locking torque requirement, when the locking torque requirement is large, a larger first preload force is required. In order not to change the compactness of the overall structure, without changing the length of the axial spring, it is necessary to adjust the number of turns, wire diameter, middle diameter, pitch and other parameters of the axial spring, so that the first preload force can be increased without changing the displacement difference between the first compressed state and the natural state.

[0060] Secondly, each radial spring in the radial spring assembly 3 is replaced with a radial spring with a larger preload force. When the locking torque requirement is large, the swinging tendency of the friction plate 5 may cause the limit plate assembly 6 to rotate, and the rotation tendency of the limit plate 6 will further bring about the torsion tendency of the axial spring. In order to resist this tendency, it is necessary to increase the thrust of the radial spring against the outer edge of the limit plate assembly 6, thereby limiting the rotation tendency of the limit plate 6 and ensuring that the axial spring can normally transmit the first preload force downward. At the same time, the stiffness of each radial spring is also increased, so that the radial spring and the pin as a whole have a stronger support force on the limit plate.

[0061] Furthermore, the power-on and power-off timing of the axial spring assembly 3 is changed. When the locking torque requirement is large, the second preload force of the axial spring also increases accordingly. In order to maintain the balance of the unlocked state, the axial spring assembly 3 is kept powered on after entering the unlocked state until it is powered off again after entering the locked state. Such a setting can ensure that the second preload force of the axial spring in the second compressed state is balanced in all aspects, including the supporting force of the radial spring assembly 2 and the maintaining effect of the contraction force of the shape memory alloy in the axial spring assembly 3 in the powered state.

[0062] Furthermore, in order to increase the locking restriction of the locking device on the friction plate 5, a bottom spring (not shown in the figure) can be installed on the bottom surface of the transmission hole 13. In the unlocked state, the bottom spring is sprung open, and the lower surface of the friction plate 5 maintains a certain distance from the upper surface of the lower shell 8, so that the movement of the friction plate 5 is not affected by the lower shell 8; in the locked state, the bottom spring is compressed, and the lower surface of the friction plate 5 is attached to the upper surface of the upper and lower shells 8. The thrust of the lower shell 8 and the external device simultaneously balances the pressure transmitted by the limit plate assembly 6, so that the friction restriction of the friction plate 5 is also achieved through the contact surface between the lower shell 8 and the friction plate 5.

[0063] Furthermore, if Figure 7 As shown, in order to prevent the lower shell 8 itself from being worn, a lower friction ring 9 is arranged on the upper surface of the lower shell 8. The lower friction ring 9 is also made of a material with a high friction coefficient and good wear resistance. For example, the material of the lower friction ring 9 is synthetic rubber, which improves the friction coefficient and wear resistance between the upper surface of the lower shell 8 and the friction plate 5. In the present invention, the combination of the lower friction ring 9 and the lower shell 8 is called a lower shell assembly 4.

[0064] Furthermore, in order to prevent the pin 7 from retracting and getting stuck under the pressure of the limit plate assembly 6, the contact angle and contact area between the pin 7 and the upper friction ring 11 are changed. In the first embodiment, the lower surface of the upper friction ring 11 is tangent to the arc-shaped outer surface of the end of the pin body of the pin 7, and there is a line contact between the two; when the locking torque increases, the pressure transmitted from the limit plate assembly 6 in the locked state is greater, so the pressure between the pin 7 and the lower friction ring 11 becomes greater, and the pin 7 is prone to unstable support for the limit plate assembly 6. In order to overcome this unstable situation, a part of the arc-shaped surface where the pin 7 contacts the upper friction ring 11 is cut off obliquely to form a new oblique plane of an ellipse at a certain angle to the center line of the pin 7; at the same time, the upper friction ring 11 is cut from the outer edge to the inside at the same angle, and an oblique plane similar to a chamfer is also formed on the upper friction ring 11. The oblique plane on the upper friction ring 11 cooperates with the oblique plane on the pin 7, so that the contact surface between the upper friction ring 11 and the pin 7 is inclined at an angle. As a result, the contact area between the upper friction ring 11 and the pin 7 is increased, and the stability of the cooperation between the two is guaranteed when the force increases; at the same time, because the force per unit area is reduced, it is not easy to have the problem of jamming when the two are separated; in addition, because the inclined contact surface is provided, during the rising process of the limit plate assembly 6, there is no need to wait for the nail body of the pin 7 to be completely offset from the limit plate assembly 6, only a partial offset is required, and the pin 7 can start to pop out from the blind hole 14, so as to start supporting the limit plate assembly 6 in advance.

[0065] like Figure 5 As shown, the matching surfaces of the pin 7 and the upper friction ring 11 can both be set as 45° inclined planes.

[0066] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by any technician familiar with the technical field within the technical scope disclosed by the present invention should be covered within the protection scope of the present invention.

Claims

1. A shape memory alloy locking device, characterized in that: The invention comprises an upper shell (1) and a lower shell (8), wherein the upper shell (1) and the lower shell (8) are assembled together to define a working space, wherein a friction plate (5) is rotatably arranged in the working space, and wherein the locking device further comprises a limit plate (10) and a limit plate control component, wherein the limit plate (10) is arranged between the friction plate (5) and the upper shell (1), and wherein the limit plate control component is made of a shape memory alloy, wherein the extension and contraction of the shape memory alloy controls the upward and downward movement of the limit plate (10), thereby realizing the unlocking and locking of the friction plate (5) by the limit plate (10).

2. The locking device according to claim 1, characterized in that: The limit plate control component is an axial spring assembly (3), and the axial spring assembly (3) comprises a group of axial springs made of shape memory alloy, and the axial springs are vertically arranged in the working space.

3. The locking device according to claim 2, characterized in that: The axial spring assembly (3) has four axial springs, and the upper ends and lower ends of the four axial springs are respectively in the same horizontal plane and are evenly distributed in the circumferential direction.

4. The locking device according to claim 3, characterized in that: One end of the axial spring is connected to the upper shell (1), and the other end of the axial spring is connected to the upper surface of the limiting plate (10).

5. The locking device according to claim 4, characterized in that: The axial spring assembly (3) is caused by the axial springs all entering a first compression state to achieve the pressing of the limit plate (10) on the friction plate (5).

6. The locking device according to claim 5, characterized in that: The axial spring assembly (3) realizes a dynamic separation process of the limit plate (10) from the friction plate (5) by energizing the shape memory alloy.

7. The locking device according to claim 6, characterized in that: The axial spring assembly (3) realizes a static separation state of the limit plate (10) from the friction plate (5) by the axial springs entering a second compression state, wherein the degree of compression of the axial springs in the second compression state is greater than the degree of compression of the axial springs in the first compression state.

8. The locking device according to claim 7, characterized in that: The upper shell (1) comprises an upper shell body and four inverted L-shaped support columns (12) extending downward, wherein the support columns (12) comprise a transverse column and a vertical column, wherein the transverse column and the vertical column are perpendicular to each other and correspond to two sides of the inverted L shape; the support columns (12) are evenly distributed along the circumference of the edge of the upper shell body, and the height of the inner surface of the vertical column of the support column (12) defines the height of the working space.

9. The locking device according to claim 8, characterized in that: The cross column of the support column (12) is provided with a mounting hole (15), and the axial springs in the axial spring assembly (3) are respectively mounted in the mounting holes (15).

10. The locking device according to claim 9, characterized in that: An upper friction ring (11) is fixedly connected to the lower surface of the limiting plate (10).

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