Corrosion test sample polishing device

Abstract

The utility model discloses a corrosion test sample polishing device which comprises a test bed, a rotary driving source, a fixing seat, a rotary connecting shaft, a fixing mechanism, an extension fixing rod, a tip alignment connecting seat, a tip alignment connecting shaft and a tip, the rotary driving source is fixedly installed on the test bed, and the rotary driving source is provided with an output rotating end; the fixed seat is fixedly arranged on the test bed, and the fixed seat is provided with a rotary connecting hole; the rotary connecting shaft is rotatably mounted in the rotary connecting hole of the fixed seat, and the rotary connecting shaft is in transmission connection with the output rotary end of the rotary driving source; the fixing mechanism is fixedly mounted on the rotary connecting shaft, and the fixing mechanism is suitable for being acted to fix one end of a sample; and the extending fixed rod is fixedly mounted on the fixed seat. The device can simplify the operation process and improve the polishing precision, has good adaptability, and can adapt to small-size samples.

Description

Technical Field

[0001] This utility model relates to a polishing device for corrosion test samples, belonging to the field of corrosion test technology. Background Technology

[0002] In the field of hydrogen sulfide stress corrosion testing (SSC) for metallic materials, the surface condition of the specimen has a significant impact on the test results. Currently, the widely adopted NACE™ 0177 standard in industry sets forth clear requirements for specimen preparation, particularly in clause 8.2.6, which states: "For all materials, the average surface roughness of the reduced portion should be 0.25 μm (10 μin) or finer, as specified by the Ra value in ISO 21920-2."

[0003] In actual SSC tests, long-term experience has revealed a positive correlation between surface finish and resistance to stress corrosion cracking. That is, the higher the surface finish, the stronger the resistance of the sample to stress corrosion cracking, and the higher the pass rate of the SSC test. Currently, the industry generally only meets the standard requirement of 0.25 μm roughness, while preparation methods and equipment for higher surface finish levels (such as 0.020 μm or even 0.010 μm) have not yet formed a systematic and standardized process and apparatus.

[0004] After searching the existing technology, it was found that Chinese patent CN212020189U discloses an external cylindrical grinding machine with smooth and precise horizontal axis operation. The patent ensures smooth and precise rotation of the horizontal axis and improves the machining accuracy. However, it was found that it is not suitable for corrosion test specimens. It is mainly for industrial parts and is difficult to use for small corrosion test specimens. It is easy to cause the specimens to shift or be damaged during polishing. Summary of the Invention

[0005] The technical problem to be solved by this utility model is to overcome the defects of the prior art and provide a corrosion test sample polishing device that can simplify the operation process, improve polishing accuracy, and has good adaptability, and can adapt to samples with smaller size.

[0006] To solve the above-mentioned technical problems, the technical solution of this utility model is: a corrosion test sample polishing device, comprising:

[0007] Test bench;

[0008] A rotary drive source is fixedly installed on the test bench, and the rotary drive source is provided with an output rotation end;

[0009] A fixed base is fixedly installed on the test bench, and the fixed base is provided with a rotatable connection hole;

[0010] A rotary connecting shaft is rotatably mounted in the rotary connecting hole of the fixed base, and the rotary connecting shaft is connected to the output rotary end of the rotary drive source.

[0011] A fixing mechanism is fixedly mounted on the rotary connecting shaft, and the fixing mechanism is adapted to be actuated to fix one end of the sample.

[0012] An extension fixing rod is fixedly installed on the fixing base;

[0013] A pointed connector is provided with a sliding groove that matches the extension fixing rod. The pointed connector is slidably disposed on the extension fixing rod, and the pointed connector is adapted to be limited on the extension fixing rod after sliding into position. The pointed connector is provided with a connecting shaft guide hole, and the pointed connecting shaft is adapted to be limited on the pointed connector after moving into position.

[0014] A pointed connecting shaft, wherein the pointed connecting shaft is movably installed in the connecting shaft guide hole of the pointed connecting seat;

[0015] A tip is fixedly mounted on the end of the tip connecting shaft facing the rotating connecting shaft, and the tip is adapted to abut against the rotation center position of the other end of the sample.

[0016] Furthermore, a specific structure of a transmission mechanism is provided, wherein a transmission mechanism is provided between the rotary drive source and the rotary connecting shaft, the transmission mechanism comprising:

[0017] A drive wheel is mounted on the output rotating end of the rotary drive source;

[0018] At least one driven wheel, the driven wheel being mounted on the rotary connecting shaft;

[0019] A transmission belt is fitted onto the outer rings of the driving pulley and the driven pulley.

[0020] Furthermore, there are three driven wheels, and the diameters of the three driven wheels increase sequentially side by side along the axial direction.

[0021] Furthermore, the corrosion test specimen polishing device also includes a speed adjustment controller, which is electrically connected to the rotary drive source and is adapted to adjust the speed of the rotary drive source.

[0022] Furthermore, the fixing mechanism includes:

[0023] A chuck is mounted on the end of the rotary connecting shaft. The chuck has a clamping hole extending axially. The outer surface of the chuck is a conical surface. The chuck has multiple radial contraction slots evenly distributed circumferentially along the axial direction.

[0024] A locking sleeve is threaded to the outer surface of the rotating connecting shaft, and the inner wall of the locking sleeve is formed with a clamping cone surface that mates with the cone surface of the chuck.

[0025] The clamp is adapted to be radially contracted by the rotation of the locking sleeve to clamp and fix one end of the sample.

[0026] Furthermore, the tip connector is provided with a threaded hole extending to the side that contacts the extension fixing rod;

[0027] The corrosion test specimen polishing device also includes an axial locking mechanism, which comprises:

[0028] A rotating locking rod is threaded into the threaded hole, and the inner end of the rotating locking rod is adapted to abut against the outer surface of the extension fixing rod.

[0029] Furthermore, the tip connector is provided with a transverse through hole, which extends through the tip connector to the connecting shaft guide hole;

[0030] The corrosion test specimen polishing device also includes a locking mechanism for the pointed connecting shaft, which comprises:

[0031] An adjusting threaded post is threadedly connected to the transverse through hole;

[0032] An eccentric block is fixedly installed on the inner end of the adjusting threaded column. The eccentric block has an arc-shaped contact surface that matches the outer surface of the connecting shaft. The eccentric block is adapted to contact the outer surface of the connecting shaft and generate a clamping force when the adjusting threaded column is rotated.

[0033] Furthermore, the corrosion test sample polishing device also includes a control switch, which is electrically connected to the rotary drive source and is adapted to control the start and stop of the rotary drive source.

[0034] Furthermore, a specific type of control switch is provided, wherein the control switch is a foot switch.

[0035] Furthermore, the tip-connecting seat is provided with a connecting rod that is hinged to the tip-connecting seat; the corrosion test sample polishing device also includes a connecting rod adjusting rod, one end of which is hinged to the connecting rod, the middle of which is provided with a clearance groove, the tip-connecting shaft passing through the clearance groove, and the tip-connecting shaft being hinged to the connecting rod adjusting rod via a connecting shaft, the other end of which is an operating end.

[0036] By adopting the above technical solution, this utility model has the following beneficial effects:

[0037] When using the corrosion test sample polishing device of this utility model, first place one end of the sample into the fixing mechanism and clamp it. Then move the tip connecting seat along the extension fixing rod to maintain an appropriate position with the other end of the sample and lock it. Then move the tip connecting shaft to drive the tip to abut against the rotation center position of the other end of the sample and lock it. Finally, start the rotation drive source to drive the sample to rotate. Then use multiple polishing test papers to polish in sequence. Finally, use a cloth to polish to complete the polishing process.

[0038] In addition, the tip connector adopts a sliding groove design, slides on the extension fixing rod, and can be locked on the extension fixing rod, so that the device can adapt to samples of different lengths; the tip connecting shaft is movably installed in the connecting shaft guide hole of the tip connector, and the tip can accurately abut the end of the sample; the speed adjustment controller can control the rotation speed of the rotary drive source, and the start and stop of the rotary drive source can be controlled by the foot switch, so that the operator can free up their hands to focus on the polishing work.

[0039] In summary, the corrosion test sample polishing device provided by this utility model can fix various corrosion test samples and polish them, solving the problems of unstable sample fixation and complicated operation in the prior art, and providing sample surface treatment equipment for corrosion test research. Attached Figure Description

[0040] Figure 1 This is a three-dimensional structural schematic diagram of the corrosion test sample polishing device of this utility model;

[0041] Figure 2 for Figure 1 A magnified view of part A in the middle. Detailed Implementation

[0042] To make the contents of this utility model easier to understand, the present utility model will be further described in detail below with reference to specific embodiments and accompanying drawings.

[0043] like Figure 1-2 As shown, a corrosion test specimen polishing device includes:

[0044] Test bench 1;

[0045] Rotary drive source 2 is fixedly installed on test bench 1 and has an output rotation end;

[0046] Fixing base 3 is fixedly installed on the test bench 1, and fixing base 3 is provided with a rotating connection hole;

[0047] Rotary connecting shaft 4 is rotatably mounted in the rotary connecting hole of the fixed base 3, and the rotary connecting shaft 4 is connected to the output rotary end of the rotary drive source 2.

[0048] The fixing mechanism is fixedly installed on the rotary connecting shaft 4, and the fixing mechanism is adapted to be actuated to fix one end of the sample.

[0049] Extension fixing rod 6 is fixedly installed on fixing base 3;

[0050] The tip connector 7 is provided with a sliding groove that matches the extension fixing rod 6. The tip connector 7 is slidably disposed on the extension fixing rod 6, and the tip connector 7 is adapted to be limited on the extension fixing rod 6 after sliding into position. The tip connector 7 is provided with a connecting shaft guide hole.

[0051] The tip-connecting shaft 8 is movably installed in the connecting shaft guide hole of the tip-connecting seat 7, and the tip-connecting shaft 8 is adapted to be fixed on the tip-connecting seat 7 after it is moved into position.

[0052] Tip 9 is fixedly mounted on the end of the tip connecting shaft 8 facing the rotating connecting shaft 4. Tip 9 is adapted to abut the rotation center position of the other end of the sample.

[0053] In this embodiment, as Figure 1 As shown, first, one end of the sample is placed into the fixing mechanism and clamped. Then, the tip connecting seat 7 is moved along the extension fixing rod 6 and locked to achieve coarse adjustment of the tip 9 position. Then, the tip 9 is driven to abut against the rotation center position of the other end of the sample by moving the tip connecting shaft 8 and then locked. Finally, the rotation drive source 2 is started to drive the sample to rotate. Then, multiple polishing test papers are used to polish in sequence, and finally, a cloth is used to polish to complete the polishing process.

[0054] Before the sample is installed on the fixing mechanism, paper tape can be wrapped around one end of the sample. The end with the paper tape is then placed into the fixing mechanism and clamped. During polishing, the polishing paper can be polished step by step from W28→W14→W10→W7→W5. Finally, a velvet cloth is used. Metallographic polishing agent can also be added to the test paper or sample during polishing. In this embodiment, the two ends of the sample are provided with threads, which are not shown in the figure. In addition, slots for the center 9 to abut are provided on both ends of the sample.

[0055] Specifically, such as Figure 1As shown, a transmission mechanism is provided between the rotary drive source 2 and the rotary connecting shaft 4. The transmission mechanism includes:

[0056] Drive wheel 11 is mounted on the output rotating end of rotary drive source 2;

[0057] Three driven wheels 12 are mounted on the rotary connecting shaft 4;

[0058] The transmission belt 13 is sleeved on the outer ring of the driving pulley 11 and the driven pulley 12.

[0059] Specifically, such as Figure 1 As shown, there are three driven wheels 12, and the diameters of the three driven wheels 12 increase sequentially along the axial direction.

[0060] In this embodiment, as Figure 1 As shown, the diameters of the three driven wheels 12 increase sequentially along the axial direction, allowing the corrosion test sample polishing device to achieve different transmission ratios and thus different rotational speeds by selecting driven wheels 12 of different diameters. When the transmission belt 13 is fitted onto the driven wheel 12 with a smaller diameter, the rotational speed of the rotating connecting shaft 4 is higher; when the transmission belt 13 is fitted onto the driven wheel 12 with a larger diameter, the rotational speed of the rotating connecting shaft 4 is lower. In actual operation, the operator can select a suitable rotational speed by adjusting the position of the transmission belt 13 according to the sample material and polishing requirements. In some embodiments, the number of driven wheels 12 is not limited to three and can be set according to specific needs.

[0061] In this embodiment, the rotary drive source 2 is preferably an electric motor, but it can also be a hydraulic motor, a pneumatic motor, or a combination of one of these with a reducer, used to provide rotational power. The motor transmits the rotational power to the driven wheel 12 via the drive wheel 11, and the power transmission is achieved through the transmission belt 13. The motor can be an AC motor or a DC motor, controlled by a motor drive circuit to adapt to different polishing process requirements. The transmission belt 13 can be a V-belt, a synchronous belt, or a flat belt. In this embodiment, the maximum speed of the motor is 4500 rpm.

[0062] Specifically, such as Figure 1 As shown, the corrosion test sample polishing device also includes a speed adjustment controller 14, which is electrically connected to the rotary drive source 2 and is adapted to adjust the speed of the rotary drive source 2.

[0063] In this embodiment, as Figure 1As shown, the speed control controller 14 is electrically connected to the rotary drive source 2 and is used to adjust the output speed of the rotary drive source 2, thereby controlling the rotation speed of the sample. The speed control controller 14 controls the operating state of the rotary drive source 2 through electrical signals, allowing the operator to precisely adjust the rotation speed according to different sample materials and polishing process requirements. During the polishing process, different speeds can be set for polishing materials of different particle sizes. For example, a lower speed can be used when using coarse sandpaper, while a higher speed can be used when using fine sandpaper and cloth for fine polishing.

[0064] The speed control controller 14 is equipped with a rotary, button or touch screen control interface. The speed control controller 14 can also have a speed display function, so that the operator can intuitively understand the actual operating speed of the current rotary drive source 2. The preferred speed is 2200 rpm.

[0065] The speed regulation controller 14 can be a frequency converter, which is existing technology and will not be described in detail in this embodiment.

[0066] Specifically, such as Figure 1-2 As shown, the fixing mechanism includes:

[0067] The chuck 51 is mounted on the end of the rotary connecting shaft 4. The chuck 51 has a clamping hole extending along the axial direction. The outer surface of the chuck 51 is a conical surface. The chuck 51 has multiple radial shrinkage slits evenly distributed along the circumference along the axial direction.

[0068] Locking sleeve 52 is threadedly connected to the outer surface of the rotating connecting shaft 4, and the inner wall of locking sleeve 52 is formed with a clamping cone surface that matches the cone surface of chuck 51.

[0069] The chuck 51 is adapted to be radially contracted by the rotation of the locking sleeve 52 to clamp and fix one end of the sample.

[0070] In this embodiment, as Figure 1 As shown, the chuck 51, as the core component of the fixing mechanism, has a conical hollow structure and a radial contraction joint design, which allows it to deform radially when subjected to external force. When the operator inserts one end of the sample into the chuck 51, the locking sleeve 52 is rotated to move along the axial direction of the chuck 51. The conical surface of the locking sleeve 52 applies radial pressure to the chuck 51, causing the chuck 51 to contract radially, thereby firmly clamping the sample.

[0071] The radial shrinkage slits of the chuck 51 are evenly distributed circumferentially. In some embodiments, the number of radial shrinkage slits can be adjusted according to the sample size and shape to accommodate samples of different diameters. The operator can control the clamping force by adjusting the rotation angle of the locking sleeve 52.

[0072] Specifically, such as Figure 1 As shown, the tip connector 7 is provided with a threaded hole that extends through to the side that contacts the extension fixing rod 6;

[0073] The corrosion test specimen polishing device also includes an axial locking mechanism, which includes:

[0074] The rotating locking rod 151 is threaded into the threaded hole, and the inner end of the rotating locking rod 151 is adapted to abut against the outer surface of the extension fixing rod 6.

[0075] In this embodiment, as Figure 1 As shown, the axial locking mechanism locks the position of the tip connector 7 on the extension fixing rod 6 by rotating the locking rod 151. When the operator needs to adjust the position of the tip connector 7, they can first loosen the locking rod 151 so that its inner end is no longer in contact with the outer surface of the extension fixing rod 6, at which point the tip connector 7 can slide freely on the extension fixing rod 6. After finding a suitable position, the operator rotates the locking rod 151 so that its inner end tightly abuts against the outer surface of the extension fixing rod 6, thereby firmly locking the tip connector 7 in the designated position on the extension fixing rod 6.

[0076] Specifically, such as Figure 1 As shown, the tip connector 7 is provided with a transverse through hole, which extends through the tip connector 7 to the guide hole of the connecting shaft.

[0077] The corrosion test specimen polishing device also includes a locking mechanism for the pointed connecting shaft, which includes:

[0078] Adjusting threaded post 161 is threadedly connected to the transverse through hole;

[0079] An eccentric block is fixedly installed on the inner end of the adjusting threaded column 161. The eccentric block has an arc-shaped contact surface that matches the outer surface of the connecting shaft. The eccentric block is adapted to contact the outer surface of the connecting shaft 8 and generate a clamping force when the adjusting threaded column 161 is rotated.

[0080] In this embodiment, as Figure 1 As shown, the locking mechanism for the mating tip connecting shaft achieves precise positioning and locking of the mating tip connecting shaft 8 through the cooperation of the adjusting threaded post 161 and the abutting eccentric block. When the operator rotates the adjusting threaded post 161, the abutting eccentric block fixed at its inner end moves accordingly. Since the abutting eccentric block has an arc-shaped contact surface that mates with the outer surface of the mating tip connecting shaft 8, when the abutting eccentric block moves to a certain position, its arc-shaped contact surface contacts the outer surface of the mating tip connecting shaft 8, and as the adjusting threaded post 161 continues to rotate, a clamping force is generated, thereby firmly locking the mating tip connecting shaft 8 in the connecting shaft guide hole of the mating tip connecting seat 7.

[0081] Specifically, such as Figure 1 As shown, the corrosion test sample polishing device also includes a control switch 17, which is electrically connected to the rotary drive source 2 and is adapted to control the start and stop of the rotary drive source 2.

[0082] Specifically, such as Figure 1 As shown, control switch 17 is a foot switch.

[0083] In this embodiment, as Figure 1 As shown, control switch 17 is electrically connected to rotary drive source 2 and is used to control the start and stop of rotary drive source 2. Control switch 17 is designed as a foot switch, allowing the operator to control the start and stop of the equipment by foot movement while operating the polishing process with both hands. This design allows the operator to free up their hands to focus on the sample polishing work during the polishing process. The foot switch adopts an anti-slip design with uneven anti-slip texture on the surface.

[0084] Specifically, such as Figure 1 As shown, the tip connector 7 is provided with a connecting rod 18 that is hinged to the tip connector 7;

[0085] The corrosion test specimen polishing device also includes a connecting rod adjusting rod 19. One end of the connecting rod adjusting rod 19 is hinged to the connecting rod 18. The middle part of the connecting rod adjusting rod 19 is provided with a clearance groove. The tip connecting shaft 8 passes through the clearance groove and is hinged to the connecting rod adjusting rod 19 through a connecting shaft. The other end of the connecting rod adjusting rod 19 is the operating end.

[0086] In this embodiment, as Figure 1 As shown, connecting rod 18 provides a hinge point for connecting rod adjusting rod 19. A connecting hole can be provided on the tip connecting shaft 8 to accommodate the connecting shaft in the middle of connecting rod adjusting rod 19, forming a hinge point. This structural design allows connecting rod adjusting rod 19 to move axially along the tip connecting shaft 8 with the hinge point of connecting rod 18 as the origin during operation. When the operator pushes or pulls the operating end of connecting rod adjusting rod 19, the force is transmitted through the two hinge points, driving tip connecting shaft 8 to move axially within the connecting shaft guide hole. During use, the operator first adjusts the position of tip connecting seat 7, then fine-tunes the position of tip 9 through connecting rod adjusting rod 19, and finally locks tip connecting shaft 8 to complete the sample installation.

[0087] The specific embodiments described above further illustrate the technical problems, technical solutions, and beneficial effects of this utility model. It should be understood that the above descriptions are merely specific embodiments of this utility model and are not intended to limit this utility model. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this utility model should be included within the protection scope of this utility model.

Claims

1. A polishing device for corrosion test specimens, characterized in that, include: Test bench (1); A rotary drive source (2) is fixedly installed on the test bench (1), and the rotary drive source (2) is provided with an output rotation end; A fixed base (3) is fixedly installed on the test bench (1), and the fixed base (3) is provided with a rotating connection hole; A rotating connecting shaft (4) is rotatably mounted in the rotating connecting hole of the fixed base (3), and the rotating connecting shaft (4) is connected to the output rotating end of the rotating drive source (2). A fixing mechanism is fixedly installed on the rotating connecting shaft (4), and the fixing mechanism is adapted to be actuated to fix one end of the sample; An extension fixing rod (6) is fixedly installed on the fixing seat (3); A tip-connecting seat (7) is provided with a sliding groove that matches the extension fixing rod (6). The tip-connecting seat (7) is slidably disposed on the extension fixing rod (6), and the tip-connecting seat (7) is adapted to be limited on the extension fixing rod (6) after sliding into position. The tip-connecting seat (7) is provided with a connecting shaft guide hole. A pointed connecting shaft (8) is movably installed in the connecting shaft guide hole of the pointed connecting seat (7), and the pointed connecting shaft (8) is adapted to be fixed on the pointed connecting seat (7) after it is moved into position; Tip (9), which is fixedly mounted on the end of the tip connecting shaft (8) facing the rotating connecting shaft (4), is adapted to abut the rotation center position of the other end of the sample.

2. The corrosion test specimen polishing apparatus according to claim 1, characterized in that, A transmission mechanism is provided between the rotary drive source (2) and the rotary connecting shaft (4), the transmission mechanism comprising: A drive wheel (11) is mounted on the output rotating end of the rotary drive source (2); At least one driven wheel (12) is mounted on the rotary connecting shaft (4); A transmission belt (13) is fitted on the outer ring of the driving wheel (11) and the driven wheel (12).

3. The corrosion test specimen polishing apparatus according to claim 2, characterized in that, There are three driven wheels (12), and the diameters of the three driven wheels (12) increase sequentially along the axial direction.

4. The corrosion test specimen polishing apparatus according to claim 1, characterized in that, It also includes a speed regulation controller (14), which is electrically connected to the rotary drive source (2) and is adapted to regulate the speed of the rotary drive source (2).

5. The corrosion test specimen polishing apparatus according to claim 1, characterized in that, The fixing mechanism includes: The chuck (51) is mounted on the end of the rotary connecting shaft (4). The chuck (51) has a clamping hole extending along the axial direction. The outer surface of the chuck (51) is a conical surface. The chuck (51) has a plurality of radial shrinkage slits evenly distributed along the circumference along the axial direction. Locking sleeve (52) is threaded to the outer surface of the rotating connecting shaft (4), and the inner wall of the locking sleeve (52) is formed with a clamping cone surface that matches the cone surface of the chuck (51). The clamp (51) is adapted to be radially contracted by the rotation of the locking sleeve (52) to clamp and fix one end of the sample.

6. The corrosion test specimen polishing apparatus according to claim 1, characterized in that, The tip connector (7) is provided with a threaded hole that extends through to the side in contact with the extension fixing rod (6); It also includes an axial locking mechanism, which comprises: A rotating locking rod (151) is threaded into the threaded hole, and the inner end of the rotating locking rod (151) is adapted to abut against the outer surface of the extension fixing rod (6).

7. The corrosion test specimen polishing apparatus according to claim 1, characterized in that, The tip connector (7) is provided with a transverse through hole, which extends through the tip connector (7) to the connecting shaft guide hole; It also includes a locking mechanism for the pointed connecting shaft, the locking mechanism for the pointed connecting shaft comprising: An adjusting threaded post (161) is threaded into the transverse through hole; An abutting eccentric block is fixedly installed on the inner end of the adjusting threaded column (161). The abutting eccentric block has an arc-shaped contact surface that matches the outer surface of the tip connecting shaft. The abutting eccentric block is adapted to contact the outer surface of the tip connecting shaft (8) and generate a clamping force when the adjusting threaded column (161) is rotated.

8. The corrosion test specimen polishing apparatus according to claim 1, characterized in that, It also includes a control switch (17), which is electrically connected to the rotary drive source (2) and is adapted to control the start and stop of the rotary drive source (2).

9. The corrosion test specimen polishing apparatus according to claim 8, characterized in that, The control switch (17) is a foot switch.

10. The corrosion test specimen polishing apparatus according to claim 1, characterized in that, The tip connector (7) is provided with a connecting rod (18) that is hinged to the tip connector (7); It also includes a connecting rod adjusting rod (19), one end of which is hinged to the connecting rod (18), the middle part of which is provided with a clearance groove, the tip connecting shaft (8) passes through the clearance groove, and the tip connecting shaft (8) is hinged to the connecting rod adjusting rod (19) through the connecting shaft, and the other end of the connecting rod adjusting rod (19) is the operating end.

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