Micro gripper based on flexible slider-crank mechanism

Abstract

The invention discloses a micro-gripper based on a flexible slider-crank mechanism. The micro-gripper comprises a piezoelectric stretching device, a base frame, a clamping arm and the flexible slider-crank mechanism, wherein the base frame, the clamping arm and the flexible slider-crank mechanism are integrally formed. The base frame comprises a base, a base column and a mounting groove, the piezoelectric stretching device is located in the mounting groove, the flexible crank sliding block mechanism comprises two flexible curved bars, two flexible connecting rods and a driving sliding block, the driving sliding block is driven by the piezoelectric stretching device, the two ends of the driving sliding block are hinged to one ends of the flexible connecting rods respectively, and the flexible curved bars are hinged to the upper end of the base column. The root part of the clamping arm is connected with the middle part of the flexible connecting rod; the micro gripper is simple and compact in structure, stable and reliable in clamping, high in universality, remarkable in displacement amplification effect, high in structural integration level, reasonable in structural design, high in rigidity and beneficial to microminiaturization design.

Description

Technical Field

[0001] The present invention relates to the technical field of micro-grippers, and specifically refers to a micro-gripper based on a flexible crank-slider mechanism. Background Art

[0002] With the development of micro-machining and manufacturing, micro-assembly technology, and micro-electromechanical technology, the application fields of micro-grippers are becoming more and more extensive, and the structural designs of micro-grippers are becoming more diverse.

[0003] Micro-grippers generally use piezoelectric actuators as the drive. Since the output displacement of piezoelectric actuators is less than the opening and closing amount required by the clamping arms, an amplification mechanism needs to be set up to amplify and transmit the output of the piezoelectric actuators to meet the clamping requirements. The flexible displacement amplification mechanisms used in the micro-grippers of the prior art are divided into three categories according to different principles: lever amplification mechanisms, triangular amplification mechanisms, and hybrid amplification mechanisms. Among them, the commonly used triangular amplification mechanisms include diamond mechanisms, bridge mechanisms, and Scott-Russell mechanisms. The structural designs of hybrid amplification mechanisms are generally complex, and the corresponding output reliability and accuracy will also decrease. The amplification multiple output by the lever amplification mechanism depends on the rod length design, and the miniaturization design of the micro-gripper is limited. The amplified output end of the triangular amplification mechanism requires an auxiliary hinge for further transmission to achieve the clamping action of the clamping arms.

[0004] Therefore, there is still a large research space for the micro-grippers of the prior art. In view of the design concept that the simpler the mechanism, the higher the reliability, breaking through the commonly used amplification mechanisms of the existing micro-grippers, the present invention proposes a micro-gripper with a simple structure, small size, displacement output amplification based on a flexible crank-slider mechanism, and the clamping action synchronized with the amplified output. Summary of the Invention

[0005] The purpose of the present invention is to overcome the defects of the prior art and provide a micro-gripper based on a flexible crank-slider mechanism to solve the problems proposed in the above background art.

[0006] To achieve the above purpose, the technical solution of the present invention is as follows:

[0007] A micro-gripper based on a flexible crank-slider mechanism, the micro-gripper is of a symmetric structure, and it includes a piezoelectric actuator and a base frame, clamping arms, and a flexible crank-slider mechanism that are integrally formed; wherein,

[0008] The base frame includes a base and base columns. The base and the two side base columns form an installation groove in the middle. The piezoelectric actuator is installed in the installation groove and is parallel to the length direction of the clamping arm (i.e., the y-axis), and one end of it is supported by a pre-tightening structure;

[0009] The flexible crank-slider mechanism includes two flexible curved rods, two flexible connecting rods, and a driving slider. The other end of the piezoelectric actuator abuts against the driving slider. The driving slider moves along the y-axis under the drive of the piezoelectric actuator. The two ends of the driving slider are respectively hinged to one end of a flexible connecting rod. The two flexible curved rods are respectively hinged to the upper end of the base column. The other ends of the two flexible connecting rods are respectively hinged to the flexible curved rods;

[0010] The root parts of the two clamping arms are respectively fixedly connected to the middle parts of the two flexible connecting rods, and are used to move synchronously with the flexible connecting rods to realize opening and closing;

[0011] Among them, the clockwise angle γ between the flexible curved rod and the clamping direction of the clamping arm (i.e., the x-axis direction) satisfies 0° < γ 1 < 180°, and the clockwise angle γ between the flexible connecting rod and the x-axis direction satisfies 270° < γ 2 < 360°, and the clockwise angle γ between the clamping arm and the y-axis direction satisfies 90° < γ 3 < 180°.

[0012] Alternatively, the clamping arm is a normally open clamping arm, the driving slider is a driving plate with a U-shaped structure, the driving plate is arranged in the installation groove, its two upper ends are respectively hinged to the flexible connecting rod, and the other end of the piezoelectric actuator abuts against the inner lower plane of the driving plate, and the actuating force direction acting on the driving plate is along the -y-axis direction.

[0013] Furthermore, the pre-tightening structure is a pre-tightening push plate located at the bottom of the installation groove. One end of the piezoelectric actuator is supported by the pre-tightening push plate. The two ends of the pre-tightening push plate are hinged to the two groove surfaces. The base is provided with pre-tightening holes, and pre-tightening screws are installed in the pre-tightening holes, and their ends press against the pre-tightening push plate.

[0014] Alternatively, the clamping arm is a normally open clamping arm, the driving slider is a driving plate with a U-shaped structure, the driving plate is arranged in the installation groove, its two upper ends are respectively hinged to the flexible connecting rod, the normally open clamping arm and the piezoelectric actuator are located outside the same side of the driving slider, and the other end of the piezoelectric actuator abuts against the inner lower plane of the driving plate.

[0015] Furthermore, the pre-tightening structure is a pre-tightening plate with an inverted U-shaped structure. One end of the piezoelectric actuator is pressed by the pre-tightening plate. The two lower ends of the pre-tightening plate are fixedly connected to the base and sleeved outside the piezoelectric actuator. One end of the piezoelectric actuator is pre-tightened by a pre-tightening member at the top of the pre-tightening plate.

[0016] Optionally, the flexible curved rod is arranged along the y-axis, that is, γ 1 = 90°, and the angle γ between the flexible connecting rod and the x-axis direction 2 is 280° - 360°.

[0017] Furthermore, the flexible connecting rod has an inverted L-shaped structure, its upper end is hinged to the upper end of the near side of the flexible curved rod, and its lower end is hinged to the upper side end of the driving slider.

[0018] Optionally, the flexible link is arranged along the y-axis, i.e., γ 2 = 270°, and the included angle γ between the flexible curved bar and the x-axis 1 is 70° - 90°.

[0019] Furthermore, the flexible curved bar has an inverted L-shaped structure, with its upper end hinged to the proximal upper end edge of the flexible link, and its lower end hinged to the inner upper end edge of the base column.

[0020] Furthermore, a voltage stabilizing arm extends along the arm length direction of the clamping arm at the upper end edge of the base column, and an elastic pressure column is installed on the voltage stabilizing arm. The end of the elastic pressure column elastically presses the outer side surface of the middle part of the clamping arm along the x-axis.

[0021] Compared with the prior art, the micro-gripper based on the flexible crank-slider mechanism of the present invention has the following beneficial effects:

[0022] The micro-gripper has a simple and compact structure, stable and reliable clamping, and strong versatility; the piezoelectric actuator inputs a micro-scale displacement along the y-axis, which is amplified by the flexible crank-slider mechanism, and outputs a micro-displacement with at least one order of magnitude difference, showing a significant displacement amplification effect. Moreover, since the clamping arm and the flexible link are an integrated structure, the flexible crank-slider mechanism integrates amplification and opening / closing transmission output, with a high structural integration degree; in addition, the micro-gripper has a reasonable structural design, which is conducive to miniaturization design, with strong structural rigidity. The simulation results show that stress concentration mainly appears at the connection between the clamping arm and the flexible link, but it is still within the safe range, indicating the effectiveness and reliability of the structural design. Description of the Drawings

[0023] Figure 1 is the schematic diagram of the flexible crank-slider mechanism on which the micro-gripper of the present invention is based;

[0024] Figure 2 is the three-dimensional view of the micro-gripper in the first embodiment of the present invention;

[0025] Figure 3 is the front view of the micro-gripper in the first embodiment of the present invention;

[0026] Figure 4 is the front view of the micro-gripper in the second embodiment of the present invention;

[0027] Figure 5 is the three-dimensional view of the micro-gripper in the third embodiment of the present invention;

[0028] Figure 6 is the front view of the micro-gripper in the third embodiment of the present invention;

[0029] Figure 7 is the stress and strain simulation diagram of the micro-gripper in the first embodiment of the present invention;

[0030] Figure 8 Strain simulation diagram of the microgripper according to the second embodiment of the present invention.

[0031] In the figure: 1, piezoelectric actuator; 2, pre-tightening push plate; 3, base frame; 31, base column; 32, base; 33, pre-tightening hole; 4, driving slider; 5, first flexible curved rod; 6, first flexible link; 7, normally closed clamping arm; 8, voltage stabilizing arm; 81, threaded stepped hole; 9, second flexible curved rod; 10, second flexible link; 11, normally open clamping arm; 12, pre-tightening plate; 13, driving plate; A, first hinge; B, second hinge; C, third hinge; P, end of the clamping arm. Detailed implementation manners

[0032] 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 the best 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 without creative efforts shall fall within the protection scope of the present invention.

[0033] A microgripper disclosed by the present invention is based on a flexible crank-slider mechanism, and its principle is as Figure 1 shown. It includes a flexible curved rod, a flexible link, and a driving slider 4. The length of the flexible curved rod is L1, the length of the flexible link is L2, and the length of the clamping arm is L3. Among them, the driving slider 4 is the prime mover, and it realizes linear driving through the piezoelectric actuator 1. The flexible curved rod and the base frame 3 are hinged by the first hinge A, the flexible curved rod and the flexible link are hinged by the second hinge B, and the flexible link and the driving slider 4 are hinged by the third hinge C. The first hinge A, the second hinge B, and the third hinge C are all preferably single-sided straight circular flexible hinges. Under the premise of meeting the hinge stiffness requirements, the characteristics of the single-sided straight circular flexible hinge are fully utilized for compact structure design; based on Figure 1 the flexible crank-slider mechanism in the shown layout, there is a situation where the angular velocity of the flexible link is greater than the angular velocity at the third hinge C. Therefore, the flexible crank-slider mechanism in this layout has an amplification effect. According to the closed polygon vector equation, an equation is established and the derivative of the unit change amount is obtained to obtain the change amount formula of the position of the end P of the clamping arm in the x-axis direction (i.e., the clamping direction of the clamping arm) under the unit change of the driving slider 4:

[0034]

[0035] where, δ X is the single-sided amplification factor, that is, the ratio of the position change amount of the end P of the clamping arm to the driving slider 4;

[0036] In the design process of the flexible crank-slider mechanism, according to the required amplification factor, first, it is necessary to determine the clockwise angle γ between the flexible curved rod and the x-axis direction 1and the clockwise angle γ between the flexible link and the x-axis 2 , secondly, determine the length of the flexible link. Since the length of the clamping arm and the clockwise angle γ between the clamping arm and the y-axis 3 have little influence, values can be selected according to actual needs; among them, based on the flexible crank-slider mechanism under this layout, the constraint conditions are obtained: the clockwise angle between the flexible curved rod and the x-axis is 0° < γ 1 < 180°, the clockwise angle between the flexible link and the x-axis is 270° < γ 2 < 360°, and the clockwise angle between the clamping arm and the y-axis is 90° < γ 3 < 180°;

[0037] Example 1: As Figure 2 and Figure 3 shown, a micro-gripper based on a flexible crank-slider mechanism. The micro-gripper is a symmetric structure, suitable for centering clamping operations. It is integrally formed with a base frame 3, a clamping arm, and a flexible crank-slider mechanism through wire cutting;

[0038] The base frame 3 as a support is cut to form a base 32, base columns 31 on both sides, and an installation groove in the middle. The piezoelectric actuator 1 is installed in the installation groove and is parallel to the length direction of the clamping arm (i.e., Figure 1 the y-axis shown in

[0039] ). A pre-tightening push plate 2 is arranged at the bottom of the installation groove. The lower end of the piezoelectric actuator 1 is supported by the piezoelectric actuator 1. Both ends of the pre-tightening push plate 2 are hinged to the two side surfaces of the installation groove through guiding beams. The base 32 is provided with a pre-tightening hole 33, which is directly opposite to the middle of the pre-tightening push plate 2. A pre-tightening screw is installed in the pre-tightening hole 33, and its end presses against the pre-tightening push plate 2 to apply a pre-tightening force to the lower end of the piezoelectric actuator 1; 1 The micro-gripper in this embodiment is a normally closed gripper. The two clamping arms are normally closed clamping arms 7, and both are synchronously driven by the flexible crank-slider mechanism at their lower ends to open and close. The upper end of the piezoelectric actuator 1 is pressed against the lower plane of the driving slider 4 to apply a driving force along the y-axis. First, determine the setting angle γ 1 of the first flexible curved rod 5. In order to obtain a more compact structure, as an optimal design, the first flexible curved rod 5 is arranged along the y-axis, that is, γ 2 = 90°. It is hinged to the inner edge of the upper end of the base column 31 through the first hinge A and extends along the y-axis. Its upper end is connected to the first flexible link 6 through the second hinge B. Secondly, determine the initial angle γ X of the first flexible link 6. It can be seen from Equation (1) that the shorter the length L2 of the flexible link, the larger the magnification factor δ 2 . And according to the relationship between the initial angle γ 2 and the length L2 of the flexible link, when the initial angle γ 2The increase is sharply shortened, and the initial angle γ 2 When it is greater than 280°, the shortening of the rod length L2 is not obvious. Therefore, the initial angle γ 2 should be between 280° and 360°. To ensure the rigidity and machinability of the mechanism, the rod length L2 should not be too short. In this embodiment, γ 2 is preferably 295.5°. Finally, the rod length L2 of the first flexible link 6 (i.e., the distance between the second hinge point B and the second hinge point C) is determined. In order to make the structure more compact while meeting the rod length requirements, the first flexible link 6 has an inverted L-shaped structure, and the outer edge of its lower end is hinged to one end edge on the upper side of the driving slider 4 through the third hinge C;

[0040] The root of the normally closed clamping arm 7 and the middle part of the inner side of the flexible link are of an integral structure, and the two normally closed clamping arms 7 are formed in a state where the end points P are mutually closed along the y-axis direction or slightly inclined;

[0041] To ensure that the normally closed clamping arm 7 maintains the initial stable closed state, a pre-tightening force must be applied to both ends of the micro-gripper. Using the integral molding pre-tightening support of the base frame 3, referring again to Figure 2 and Figure 3 , the upper end edge of the base column 31 extends along the y-axis direction of the clamping arm to form a voltage stabilizing arm 8 located outside the first flexible curved rod 5. The voltage stabilizing arm 8 is L-shaped, and its end bends and extends towards the normally closed clamping arm 7 to be close to the outer side surface of the clamping arm. A threaded step hole 81 is provided on the voltage stabilizing arm 8. One end of an elastic compression column (not shown in the figure) is clamped in the threaded step hole 81 and connected to a compression spring (not shown in the figure). The other end elastically presses the outer side surface of the middle part of the clamping arm along the x-axis direction, applying a pre-tightening force along the clamping direction. The threaded step hole 81 is blocked by a screw and supports the compression spring.

[0042] With the parameter settings of the clamping arm length L3 being 37.95 mm, the first flexible link 6 length L2 being 3.45 mm, and the initial included angle γ 3 of the clamping arm being 147.53°, the finite element analysis structure of the micro-gripper in this embodiment is as Figure 7 shown. When a displacement of 10 μm is applied, the unilateral displacement magnification factor is 22.42 times, meeting the design requirements and showing a significant displacement magnification effect; at the same time, the maximum stress of the micro-gripper is 80.82 MPa, far lower than its allowable stress of 328 MPa, indicating that the material will not be damaged. The stress concentration mainly appears at the connection between the clamping arm and the first flexible link 6, but it is still within the safe range. The simulation results verify the effectiveness and reliability of the micro-gripper design; in addition, through the modal analysis of the micro-gripper, the micro-gripper is not affected by the natural frequencies below 712.96 Hz, and the driving excitation in actual work is much less than 712.96 Hz. Therefore, this structure will not resonate during actual operation.

[0043] Embodiment 2: As shown in Figure 4The micro-gripper based on the flexible crank slider mechanism is shown as another compact structure design. The clamping arm of the micro-gripper is also a normally closed clamping arm 7, and its second flexible link 10 is parallel to the y-axis direction of the clamping arm, that is, γ 2 =270°, its lower end is hinged to the upper side edge of the driving slider 4 through the third hinge C, its upper end is hinged to the second flexible curved rod 9, the second flexible curved rod 9 is an inverted L-shaped structure, its lower end is connected to the upper inner edge of the base column 31 through the first hinge A, and the root of the clamping arm is rigidly connected to the inner middle of the second flexible link 10; determine the initial angle γ of the first flexible link 6 1 , due to structural constraints, γ 1 <90°, while in γ 1 When the range is below 90°, the magnification of the micro-gripper only changes between 0-30 times, especially below 70°, the magnification increases basically linearly. 1 <90°;

[0044] The finite element analysis structure of the micro-gripper of this embodiment is as follows: Figure 8 As shown, at the initial angle γ of the first flexible link 6 1 is 70.44°, the length of the clamping arm L3 is 38 mm, the first flexible link 6L2 is 4.24 mm, and the initial angle of the clamping arm γ 3 Under the parameter setting of 175.68°, when the piezoelectric drive applies a displacement of 10μm, the unilateral displacement amplification factor is 23.22 times, which also shows a significant displacement amplification effect;

[0045] The above describes the differences in the structural design between the micro-gripper of this embodiment and the embodiment 1. The remaining structural designs and optimized structures not involved can refer to the embodiment 1, and will not be described in detail in this embodiment.

[0046] Embodiment 3: This embodiment provides a normally open micro-gripper, such as Figures 5 - 6 As shown, the driving slider 4 is designed as a driving plate 13 of a U-shaped structure, and the driving plate 13 is embedded in the mounting groove, and its two upper ends are respectively hinged with the first flexible link 6, and the lower end of the piezoelectric extensor 1 is against the inner lower plane of the driving plate 13. When the driving plate 13 applies an actuating force along the -y axis, the two normally open clamping arms 11 are linked with the inverted L-shaped first flexible link 6, and slightly closed under the action of the actuating force. In order to reserve a closing amount between the two normally open clamping arms 11, the normally open clamping arm 11 is rigidly connected to the middle or outer edge of the upper end of the first flexible link 6, and extends upward along the y axis. The end of the normally open clamping arm 11 is detachably provided with a clamping head, and the corresponding clamping head is selected according to different normally open amounts;

[0047] The piezoelectric actuator 1 is pressed by a detachable pre-tightening plate 12. The pre-tightening plate 12 has an inverted U-shaped structure and is sleeved on the outside of the piezoelectric actuator 1 from the upper end of the piezoelectric actuator 1 downward. The two lower ends of the pre-tightening plate 12 are detachably connected to the two side planes of the base 32. A pre-tightening member is provided at the upper end of the pre-tightening plate 12, and the end of the pre-tightening member extends out from the inner upper plane of the pre-tightening plate 12 and presses on the upper end of the piezoelectric actuator 1.

[0048] The directional or positional terms such as "inner", "outer", "upper", "lower", "end", "side", "near", "x", "y", etc. mentioned in this article are based on the Figures 1 - 6 coordinate or positional relationship shown in. These terms are mainly used to better describe the present invention and its embodiments, and are not used to limit that the indicated device, element or component must have a specific orientation, or be constructed and operated in a specific orientation; in addition, the terms "first" and "second" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance;

[0049] Moreover, in addition to being able to be used to represent an orientation or positional relationship, some of the above terms may also be used to represent other meanings. For example, the terms "upper" and "inner" may also be used to represent a certain attachment relationship or connection relationship in some cases. For those of ordinary skill in the art, the specific meanings of these terms in the present invention can be understood according to specific circumstances.

[0050] Although the embodiments of the present invention have been shown and described, for those of ordinary skill in the art, it can be understood that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of the present invention. The scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A micro-gripper based on a flexible crank slider mechanism, characterized in that: The micro-gripper is a symmetrical structure, which includes a piezoelectric extensor and an integrally formed base frame, a clamping arm and a flexible crank slider mechanism; wherein, The base frame includes a base and a base column, the base and the base columns on both sides form a mounting groove in the middle, the piezoelectric extensor is installed in the mounting groove and parallel to the length direction of the clamping arm (i.e., the y-axis), and one end of the piezoelectric extensor is supported by a pre-tightening structure; The flexible crank slider mechanism includes two flexible crank rods, two flexible connecting rods and a driving slider, the other end of the piezoelectric extensor abuts against the driving slider, and the driving slider moves along the y-axis under the drive of the piezoelectric extensor, and the two ends of the driving slider are respectively hinged to one end of the flexible connecting rod, the two flexible crank rods are respectively hinged to the upper end of the base column, and the other ends of the two flexible connecting rods are respectively hinged to the flexible crank rod; The bases of the two clamping arms are respectively fixedly connected to the middles of the two flexible connecting rods, and are used to move synchronously with the flexible connecting rods to achieve opening and closing; Among them, the clockwise angle between the flexible curved rod and the clamping direction (i.e., the x-axis direction) of the clamping arm is 0°<γ1<180°, the clockwise angle between the flexible connecting rod and the x-axis direction is 270°<γ2<360°, and the clockwise angle between the clamping arm and the y-axis direction is 90°<γ3<180°.

2. The micro-gripper based on the flexible crank slider mechanism according to claim 1 is characterized in that: The clamping arm is a normally closed clamping arm. The other end of the piezoelectric extensor abuts against the lower plane of the driving slider, and the actuating force acting on the driving slider is in the y-axis direction.

3. The micro-gripper based on the flexible crank slider mechanism according to claim 2 is characterized in that: The pre-tightening structure is a pre-tightening push plate located at the bottom of the mounting groove, one end of the piezoelectric extensor is supported by the pre-tightening push plate, both ends of the pre-tightening push plate are hinged to the two groove surfaces, the base is provided with a pre-tightening hole, the pre-tightening screw is installed in the pre-tightening hole, and its end is pressed against the pre-tightening push plate.

4. The micro-gripper based on the flexible crank slider mechanism according to claim 1, characterized in that: The clamping arm is a normally open clamping arm, the driving slider is a driving plate of a U-shaped structure, the driving plate is arranged in the mounting groove, and its two upper ends are respectively hinged to the flexible connecting rod, and the other end of the piezoelectric extensor is against the inner lower plane of the driving plate, and the direction of the actuating force acting on the driving plate is along the -y axis.

5. The micro-gripper based on the flexible crank slider mechanism according to claim 4 is characterized in that: The pre-tightening structure is a pre-tightening plate with an inverted U-shaped structure, one end of the piezoelectric extensor is pressed by the pre-tightening plate, the two lower ends of the pre-tightening plate are fixedly connected to the base and are sleeved outside the piezoelectric extensor, and one end of the piezoelectric extensor is pre-tightened by the pre-tightening piece on the top of the pre-tightening plate.

6. The micro-gripper based on the flexible crank slider mechanism according to any one of claims 1 to 5, characterized in that: The flexible curved rod is arranged along the y-axis, that is, γ1=90°, and the angle γ2 between the flexible connecting rod and the x-axis is 280°-360°.

7. The micro-gripper based on the flexible crank slider mechanism according to claim 6, characterized in that: The flexible connecting rod is in an inverted L-shaped structure, the upper end of which is hinged to the proximal upper end of the flexible curved rod, and the lower end of which is hinged to the upper side end of the driving slider.

8. The micro-gripper based on the flexible crank slider mechanism according to any one of claims 1 to 5, characterized in that: The flexible connecting rod is arranged along the y-axis, that is, γ2=270°, and the angle γ1 between the flexible curved rod and the x-axis direction is 70°-90°.

9. The micro-gripper based on the flexible crank slider mechanism according to claim 8, characterized in that: The flexible curved rod is in an inverted L-shaped structure, the upper end of which is hinged to the proximal upper end of the flexible connecting rod, and the lower end of which is hinged to the inner side of the upper end of the base column.

10. The micro-gripper based on the flexible crank slider mechanism according to claim 2 or 3, characterized in that: The upper end of the base column extends along the arm length direction of the clamping arm to form a pressure stabilizing arm, and an elastic pressure column is installed on the pressure stabilizing arm. The end of the elastic pressure column elastically presses the outer side surface of the middle part of the clamping arm along the x-axis.

Images