Chuck for high-strength fatigue testing machine for step chain

Abstract

The invention relates to the technical field of fatigue testing machines, in particular to a chuck for a high-strength fatigue testing machine for a step chain, which comprises a chuck body and a connecting pin shaft, two clamping plates are symmetrically arranged on the chuck body, a clamping opening for placing a chain is arranged between the two clamping plates, pin holes are formed in the clamping plates, and the pin holes are connected with the connecting pin shaft. A bolt hole is further formed in the top of the chuck body, a boss is arranged on the top of the side, away from the clamping plate, of the chuck body, a rotating plate is rotationally installed on the boss, a torsional spring is arranged at the rotating joint of the rotating plate and the boss, and a protruding block is fixedly installed at the bottom of the rotating plate, inserted into the clamping opening and connected with the side, away from the boss, of the connecting pin shaft in an abutting mode. By arranging the rotating plate and the protruding block, the protruding block is clamped in a chain knot to abut against the connecting pin shaft, the stress of the clamping plate on the chuck body is shared when a step chain is subjected to a fatigue experiment, the situation that the clamping plate is fractured due to stress in the step chain fatigue experiment is avoided, the service life of the chuck is prolonged, and it is guaranteed that the experiment is conducted smoothly.

Description

Technical Field

[0001] The present invention relates to the technical field of fatigue testing machines, and particularly to a chuck for a high-strength fatigue testing machine for a step chain. Background Art

[0002] After the production of the chain, fatigue tests need to be carried out to facilitate the determination of the replacement time of the chain. Especially in occasions with high safety requirements, such as the step chain used in elevators, the fatigue strength requirements for the chain are more stringent. Therefore, high-strength fatigue tests need to be repeatedly carried out on the chain.

[0003] During the experiment, usually a section of the chain is clamped on the testing machine, and the testing machine continuously applies a tensile force to the chain to test the load-bearing capacity of the chain. When clamping the chain onto the testing machine, a chuck is used. The existing chucks for testing machines usually install two clamping plates on a fixed block. After clamping the chain between the two clamping plates, a pin shaft is passed through the pin holes on the clamping plates to connect the chain to the clamping plates. However, for the chucks in the prior art, the clamping plates are prone to damage after long-term use. If the clamping plates break and are damaged during the experiment, the experiment will be invalidated and need to be re-conducted. And each experiment on the chain takes a long time, and re-conducting the experiment will inevitably waste a lot of time. Moreover, after the clamping plates break, the chain may hit the testing equipment after detaching from the chuck, causing relatively high losses.

[0004] In order to improve the strength of the chuck, a Chinese utility model patent with the application number: CN202221368545.4 and the name of "A Chuck for a High-Strength Fatigue Testing Machine for Roller Chains" designed a chuck, which includes a chuck body and a connecting pin shaft. On both sides of one side of the chuck body are positioning blocks, and connecting holes are provided on the positioning blocks. Between the positioning blocks is a chain installation hole; a stepped structure protrudes outward from the outside of the positioning blocks, and the cross-section of the chain installation hole is in a "T" shape, avoiding contact with the outer link plate and pin shaft of the chain, ensuring that there is no interference between the test chain and the chuck during the test process, and increasing the fatigue life by 200% compared with the original structure chuck, thereby realizing the reduction of test costs.

[0005] The above-mentioned utility model patent strengthens the strength of the chuck to a certain extent by protruding a stepped structure outward from the outside of the positioning blocks, but the improved strength is limited. Moreover, the step chain has higher safety requirements, so the requirements for its fatigue strength are also higher. The load applied during the experiment will be greater, and the number of experiments will also be more. In order to ensure the service life of the chuck, higher requirements are placed on the strength of the chuck. Strengthening the strength of the chuck by adding a stepped structure is slightly insufficient and further improvement is needed.

[0006] Therefore, a chuck for a high-strength fatigue testing machine for a step chain is proposed. Summary of the Invention

[0007] The purpose of the present invention is to provide a chuck for a high-strength fatigue testing machine for a step chain, further improving the strength of the chuck to solve the problem of insufficient chuck strength and easy breakage during the test proposed in the above background technology, and to increase the service life of the chuck.

[0008] To achieve the above object, the present invention provides the following technical solutions:

[0009] A chuck for a high-strength fatigue testing machine for a step chain, comprising a chuck body and a connecting pin, two clamping plates are symmetrically arranged on the right side of the chuck body, a clamping opening for placing a chain is arranged between the two clamping plates, pin holes for inserting the connecting pin are provided on the clamping plates, the two pin holes are arranged in alignment with each other, a bolt hole is also provided on the top of the chuck body, the bolt hole passes through the top and bottom surface of the chuck body, a boss is provided on the top of the chuck body away from the clamping plate, a rotating plate is rotatably installed on the boss, a torsion spring is provided at the rotating connection between the rotating plate and the boss, the torsion spring is used to press the rotating plate to the top of the chuck, a protrusion is fixedly installed on the bottom of the rotating plate, the protrusion is inserted into the clamping opening and abuts against the side of the connecting pin away from the boss.

[0010] By setting the rotating plate and the protrusion, when in use, after the inner chain plate of the step chain is inserted into the clamping opening, the step chain is connected to the clamping head after the connecting pin is inserted into the pin hole and passes through the rotating shaft hole on the inner chain plate of the step chain. The rotating plate rotates downward to drive the protrusion to insert downward between the two inner chain plates of the step chain, and the protrusion abuts against the side of the connecting pin away from the boss. In this way, when the step chain is pulled, the two clamps limit the connecting pin, and at the same time, the rotating plate and the protrusion will also apply a pulling force to the connecting pin to prevent the step chain from escaping from the clamping opening, thereby clamping the step chain.

[0011] Due to the addition of the rotating plate and the protrusion, when the step chain is pulled, the rotating plate and the protrusion share the tension of the two splints, avoiding the two splints from breaking due to insufficient strength, and ensuring the steady progress of the fatigue test. In addition, the setting of the rotating plate can block the top of the step chain to a certain extent when the step chain is pulled to the limit and breaks, avoiding the step chain from turning upward and tilting after breaking, causing damage to the experimental equipment, and avoiding injuries to the experimenters, which helps to improve the safety during the experiment. In addition, since the protrusion abuts the connecting pin shaft from between the two splints, the contact area between the chuck and the connecting pin shaft is effectively increased, and the fulcrum between the connecting pin shaft and the chuck shaft when the step chain is pulled is increased. Since the connecting pin shaft at the chuck shaft is greatly affected by the outside world, it cannot accurately represent the experimental data of the fatigue strength of the step chain. Therefore, ensuring the strength of the connecting pin shaft at the chuck shaft can ensure the accuracy of the experimental data.

[0012] During the clamping process of the step chain, the torsion spring is arranged so that the rotating plate is always pressed downward, which can prevent the rotating plate from detaching from the clamping opening due to the vibration of the experimental equipment or other external influences during the experiment, ensuring that the rotating plate and the convex block can provide effective tensile force to the connecting pin shaft, and ensuring that the convex block and the rotating plate can effectively share the force of the clamping plate. The stability during the use of the chuck is improved.

[0013] Preferably, the pin hole is an oval hole, and one end of the pin hole is a convenient insertion end, and the other end is a contraction end. The convenient insertion end is larger than the contraction end. The diameter of the contraction end is the same as the diameter of the connecting pin shaft. The convenient insertion end smoothly contracts towards the contraction end, and the contraction direction is towards the horizontal opening direction of the clamping opening.

[0014] Since the convenient insertion end is larger than the contraction end, the diameter of the convenient insertion end is larger than the diameter of the connecting pin shaft, which can facilitate the insertion of the connecting pin shaft into the pin hole and improve the convenience of the chuck when clamping the step chain. During the experiment, the step chain is under tension, and the connecting pin shaft will be pulled towards the contraction end and stuck into the contraction end. The diameter of the contraction end is the same as that of the connecting pin shaft, which is convenient for limiting the connecting pin shaft and avoiding the shaking of the connecting pin shaft during the experiment, ensuring the stability of the connecting pin shaft during the experiment and thus ensuring the stability of the step chain during the experiment.

[0015] Preferably, two reed pieces are fixedly installed at the bottom of the rotating plate. The two reed pieces are respectively located outside the two clamping plates. The reed pieces are in a "V" shape. One end of the reed piece is a fixed end, and the fixed end is fixedly connected to the bottom of the rotating plate. The other end of the reed piece is a free end. The reed piece is used to squeeze the end of the connecting pin shaft extending out of the clamping opening when the rotating plate rotates downward and horizontally push the connecting pin shaft from the convenient insertion end towards the contraction end.

[0016] During the process of the "V"-shaped reed piece rotating downward with the rotating plate, it automatically pushes the connecting pin shaft in the pin hole towards the contraction end. The reed piece cooperates with the contraction end to completely fix the connecting pin shaft, preventing the connecting pin shaft from shaking and detaching from the pin hole during the experiment and ensuring the stable progress of the experiment. In addition, when the step chain breaks due to fatigue during the experiment, the step chain will have an impact force on the chuck body. After the reed pieces are provided, when the step chain breaks and gives an impact force in one direction to the chuck body, the reed pieces can absorb part of the impact force through elastic deformation, avoiding damage to the chuck by the impact force and helping to further improve the service life of the chuck.

[0017] Preferably, the convex block is an isosceles trapezoid. The upper base length of the isosceles trapezoid-shaped convex block is greater than the lower base length, and the waist of the isosceles trapezoid faces the direction of the convex platform. The shape of the inverted isosceles trapezoid enables the convex block to stably abut against the connecting pin shaft, avoiding gaps between the connecting pin shaft and the convex block due to assembly problems, which may cause the convex block and the rotating plate to be unable to share the tensile force received by the clamping plate during the experiment. This further improves the stability during the use of the chuck and also reduces the precision requirements during the assembly of the chuck.

[0018] Preferably, a hard layer is provided on the plane of the convex block facing the convex platform. The hard layer is made of rubber material, and anti-slip grooves are also provided on the hard layer.

[0019] Since multiple repeated experiments need to be carried out on the step chain, and during the experiment, the convex block will continuously squeeze the connecting pin shaft, and the connecting pin shaft and the convex block will be squeezed, worn, or even deformed. Due to the setting that the pin hole is larger at one end and smaller at the other end, it is very convenient to replace the pin shaft. In order to ensure that the convex block will not break away from the rotating plate due to the tensile force of the step chain during the experiment, the convex block and the rotating plate are integrally processed. If the convex block is worn, the entire rotating plate needs to be replaced, which is not conducive to saving the experimental cost. After setting the hard layer, it can be ensured that the convex block and the connecting pin shaft will not be damaged due to deformation during the experiment, so as to ensure the stable progress of the experiment. The anti-slip grooves can increase the friction force between the connecting pin shaft and the convex block, further preventing the convex block from detaching from the connecting pin shaft due to vibration during the experiment, and ensuring the pressure sharing effect of the rotating plate on the clamping plate.

[0020] Among them, the hard layer can be formed by welding a high-hardness metal on the surface of the convex block, or can be formed by processing techniques such as quenching.

[0021] Preferably, a bottom plate is fixedly installed at the bottom of the clamping plate. The bottom plate fixedly connects the two clamping plates and the chuck body together. The bottom plate connects the two clamping plates and the chuck body from the bottom of the clamping plate, further improving the strength of the clamping plate and further improving the stability during the use of the chuck.

[0022] Preferably, an elastic plate is fixedly installed on the top surface of the bottom plate. The elastic plate is parallel to the waist of the convex block on the side away from the convex platform. A card slot is provided on the plane of the convex block on the side away from the convex platform, and a hook portion for being inserted into the card slot is provided at the top of the elastic plate. When the rotating plate rotates downward and is inserted into the clamping mouth, the convex block squeezes the lower elastic plate, and the elastic plate bends and deforms in the direction away from the convex platform. When the hook portion aligns with the card slot, the hook portion is inserted into the card slot under the elastic force of the elastic plate, further preventing the rotating plate from rotating upward during the experiment, avoiding the convex block from detaching from the contact with the connecting pin shaft, and improving the stability during the use of the chuck.

[0023] Preferably, a countersunk hole is formed in the top of the rotating plate. The countersunk hole is perpendicular to the top surface of the rotating plate and penetrates the rotating plate. An unlocking rod is slidably installed inside the countersunk hole. The top of the elastic plate extends to directly below the countersunk hole to form an extension part. A spring is also arranged inside the countersunk hole, and the spring is used to keep pushing the unlocking rod upward.

[0024] The hook part on the elastic plate is caught inside the card slot to limit the convex block and prevent the convex block from moving upward. Both the convex block and the elastic plate are located between the inner link plates of the step chain, and the top is covered by the rotating plate. It is difficult for manual operation to take out the hook part from the card slot. The unlocking rod can pass through the rotating plate to press the elastic plate downward, so that the hook part disengages from the card slot, effectively improving the convenience during the use of the chuck.

[0025] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0026] 1. A chuck for a high-strength fatigue testing machine for step chains designed by the present invention is provided with a rotating plate and a convex block at the bottom of the rotating plate. The convex block is stuck in the link to abut against the connecting pin shaft, sharing the force on the clamping plate of the chuck body during the fatigue test of the step chain, avoiding the situation that the clamping plate breaks due to force during the fatigue test of the step chain, improving the service life of the chuck, and ensuring the smooth progress of the experiment.

[0027] 2. A chuck for a high-strength fatigue testing machine for step chains designed by the present invention is also provided with a bottom plate. The bottom plate fixedly connects the bottoms of the two clamping plates together, further improving the strength of the clamping plate. An elastic plate is also arranged on the bottom plate. By the hook part on the elastic plate being caught inside the card slot of the convex block, it can be avoided that the convex block disengages from the connecting pin shaft during the experiment, further ensuring that the rotating plate can stably share the force on the clamping plate during the experiment, ensuring the stability during the use of the chuck, and preventing the clamping plate from being damaged during the experiment.

[0028] 3. A chuck for a high-strength fatigue testing machine for step chains designed by the present invention has the pin hole set in a shape with one end large and one end small to facilitate the chuck to fix the step chain. A "V"-shaped reed is arranged on the rotating plate, so that when the reed rotates with the rotating plate, it can automatically squeeze the connecting pin shaft to the shrinking end of the pin hole for fixation, further improving the convenience of use. The reed can also reduce the impact of the step chain on the chuck when the step chain breaks, further improving the service life of the chuck. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 is a three-dimensional structural schematic diagram of the present invention;

[0030] Figure 2 is a front view of the present invention;

[0031] Figure 3 It is a right side view of the present invention;

[0032] Figure 4 For the present invention Figure 3 Sectional view at AA in the middle;

[0033] Figure 5 It is a schematic diagram of the three-dimensional structure when the transfer plate of the present invention rotates upward;

[0034] Figure 6 For the present invention Figure 5 The enlarged view of point B in the middle;

[0035] Figure 7 This is a schematic diagram of the three-dimensional structure of the present invention when clamping a step chain;

[0036] Figure 8 This is a schematic diagram of the internal structure of the present invention when clamping a step chain;

[0037] Figure 9 It is a schematic diagram of the state when the unlocking lever pushes the hook portion out of the card slot in the present invention.

[0038] In the figure: 1. chuck body; 2. connecting pin; 3. clamping plate; 4. clamping mouth; 5. pin hole; 501. plug-in end; 502. contraction end; 6. bolt hole; 7. boss; 8. rotating plate; 9. torsion spring; 10. bump; 11. spring leaf; 12. fixed end; 13. free end; 14. hard layer; 15. anti-skid pattern; 16. bottom plate; 17. elastic plate; 18. slot; 19. hook portion; 20. countersunk hole; 21. unlocking rod; 22. extension portion; 23. spring. DETAILED DESCRIPTION

[0039] See also Figures 1 to 9 The present invention provides a chuck for a high-strength fatigue testing machine for a step chain, and the technical solution is as follows:

[0040] A chuck for high strength fatigue testing machine for step chains, reference Figures 1 to 5, including a chuck body 1 and a connecting pin shaft 2. Two clamping plates 3 are symmetrically arranged on the right side of the chuck body 1. A bottom plate 16 is fixedly installed at the bottom of the clamping plate 3, and the bottom plate 16 fixedly connects the two clamping plates 3 and the chuck body 1 together. A clamping opening 4 for placing a chain is arranged between the two clamping plates 3. A pin hole 5 for inserting the connecting pin shaft 2 is formed on each of the clamping plates 3. The pin hole 5 is a waist-shaped hole, and one end of the pin hole 5 is a convenient insertion end 501, and the other end is a contraction end 502. The convenient insertion end 501 is larger than the contraction end 502. The diameter of the contraction end 502 is the same as the diameter of the connecting pin shaft 2. The convenient insertion end 501 smoothly contracts towards the contraction end 502, and the contraction direction is towards the horizontal opening direction of the clamping opening 4. The two pin holes 5 are arranged in alignment with each other. A bolt hole 6 is also formed at the top of the chuck body 1, and the bolt hole 6 penetrates through the top and bottom surfaces of the chuck body 1. A boss 7 is arranged at the top of the side of the chuck body 1 away from the clamping plate 3. A rotating plate 8 is rotatably installed on the boss 7. A torsion spring 9 is arranged at the rotation connection between the rotating plate 8 and the boss 7, and the torsion spring 9 is used to press the rotating plate 8 against the top of the clamping plate 3.

[0041] Reference Figure 4 , Figure 5 and Figure 6 , a convex block 10 is fixedly installed at the bottom of the rotating plate 8. The convex block 10 is an isosceles trapezoid. The upper base length of the isosceles trapezoid convex block 10 is greater than the lower base length, and the waist of the isosceles trapezoid faces the direction of the boss 7. The convex block 10 is inserted into the clamping opening 4 and abuts against the side of the connecting pin shaft 2 away from the boss 7. A hard layer 14 is formed on the plane of the convex block 10 facing the boss 7 by quenching. The hard layer 14 is made of rubber material, and anti-slip lines 15 are also formed on the hard layer 14.

[0042] Reference Figure 2 and Figure 5 , two reed pieces 11 are fixedly installed at the bottom of the rotating plate 8. The two reed pieces 11 are respectively located outside the two clamping plates 3. The reed piece 11 is in a "V" shape. One end of the reed piece 11 is a fixed end 12, and the fixed end 12 is fixedly connected to the bottom of the rotating plate 8. The other end of the reed piece 11 is a free end 13. The reed piece 11 is used to squeeze the end of the connecting pin shaft 2 extending out of the clamping opening 4 when the rotating plate 8 rotates downward, and horizontally push the connecting pin shaft 2 from the convenient insertion end 501 towards the contraction end 502.

[0043] Reference Figure 4 and Figure 5An elastic plate 17 is fixedly mounted on the top surface of the bottom plate 16. The elastic plate 17 is parallel to the waist of the protrusion 10 on the side away from the boss 7. A slot 18 is provided on the plane of the protrusion 10 on the side away from the boss 7. A hook 19 for inserting into the slot 18 is provided on the top of the elastic plate 17. A countersunk hole 20 is provided on the top of the rotating plate 8. The countersunk hole 20 is perpendicular to the top surface of the rotating plate 8 and penetrates the rotating plate 8. An unlocking rod 21 is slidably mounted inside the countersunk hole 20. The top of the elastic plate 17 is extended to form an extension 22 directly below the countersunk hole 20. A spring 23 is also provided inside the countersunk hole 20. The spring 23 is used to keep the unlocking rod 21 pushed upward.

[0044] When using, refer to Figure 4 and Figure 5 , insert the bolt into the bolt hole 6, and use the bolt to fix the chuck body 1 to the testing machine. The chuck bodies 1 are installed on the testing machine in pairs, and the clamping openings 4 on the two chuck bodies 1 are arranged opposite to each other and are located in a straight line.

[0045] During the experiment, refer to Figure 5 , Figure 7 and Figure 8 , pull the rotating plate 8 upward, insert the two inner chain plates at one end of the step chain into the clamping opening 4, and align the shaft hole of the inner chain plate with the plug-in end 501 of the pin hole 5, and then insert the connecting pin 2 from the plug-in end 501 of the pin hole 5 on one side of the clamping plate 3 and pass through the shaft holes on the two inner chain plates and out of the pin hole 5 of the clamping plate 3 on the other side. The length of the connecting pin 2 should be longer than the maximum distance between the two clamping plates 3, that is, both ends of the connecting pin 2 should extend out of the pin holes 5 of the two clamping plates 3.

[0046] Then release the rotating plate 8, refer to Figure 2 , Figure 5 , Figure 6 as well as Figures 7 to 9 , the rotating plate 8 rotates downward toward the clamping plate 3 under the action of the torsion spring 9. The protrusion 10 rotates downward and is inserted between the two inner chain plates of the step chain located at the clamping opening 4. The "V"-shaped spring leaves 11 on both sides of the rotating plate 8 respectively squeeze the two ends of the connecting pin 2 extending out of the clamping plate 3, push the connecting pin 2 toward the direction of the contraction end 502 and make the connecting pin 2 tightly clamped at the contraction end 502. The hard layer 14 on the protrusion 10 abuts against the side of the connecting pin 2 away from the boss 7. When the protrusion 10 is inserted downward between the two inner chain plates, the side of the protrusion 10 away from the boss 7 squeezes the elastic plate 17 below, and the elastic plate 17 is bent and deformed in the direction away from the boss 7. When the hook portion 19 is aligned with the card slot 18, the hook portion 19 is reset and clamped into the card slot 18 under the elastic force of the elastic plate 17, preventing the rotating plate 8 from rotating upward.

[0047] The other end of the step chain can be clamped to the other chuck body 1 in the above manner. In this way, the step chain is clamped to the testing machine. During the experiment, the testing machine can be made to drive the two chuck bodies 1 to move away from each other respectively.

[0048] After the experiment is completed, referring to Figure 5 and Figure 9 , press the unlocking lever 21 downwards. The unlocking lever 21 moves downwards and squeezes the extension part 22 on the elastic plate 17. The elastic plate 17 bends and deforms in the direction away from the boss 7, and the hook part 19 can be disengaged from the card slot 18. Then, while keeping pressing the unlocking lever 21, rotate the rotating plate 8 upwards, horizontally draw out the pin shaft from the pin hole 5, and take out the step chain from the clamping port 4, and the disassembly operation can be completed.

[0049] The above has described in detail a specific embodiment of the present invention in conjunction with the accompanying drawings, but the present invention is not limited to the described embodiment. For those skilled in the art, without departing from the principles and ideas of the present invention, various changes, modifications, substitutions, and variations made to these embodiments should still fall within the protection scope of the present invention.

Claims

1. A chuck for a high-strength fatigue testing machine for a step chain, comprising a chuck body (1) and a connecting pin shaft (2), wherein two clamping plates (3) are symmetrically arranged on the chuck body (1), a clamping opening (4) for placing a chain is arranged between the two clamping plates (3), and pin holes (5) for inserting the connecting pin shaft (2) are provided on the clamping plates (3), and the two pin holes (5) are arranged in alignment with each other, and a bolt hole (6) is also provided on the top of the chuck body (1), and the bolt hole (6) passes through the top and bottom surface of the chuck body (1), characterized in that: A boss (7) is provided at the top of the chuck body (1) away from the clamp (3), a rotating plate (8) is rotatably mounted on the boss (7), a torsion spring (9) is provided at the rotational connection between the rotating plate (8) and the boss (7), the torsion spring (9) is used to press the rotating plate (8) against the top of the clamp (3), a protrusion (10) is fixedly mounted at the bottom of the rotating plate (8), the protrusion (10) is inserted into the clamping mouth (4) and abuts against the side of the connecting pin shaft (2) away from the boss (7).

2. The chuck for a high-strength fatigue testing machine for a step chain according to claim 1, characterized in that: The pin hole (5) is a waist-shaped hole, and one end of the pin hole (5) is a plug-in end (501), and the other end is a contraction end (502). The plug-in end (501) is larger than the contraction end (502), and the diameter of the contraction end (502) is the same as the diameter of the connecting pin shaft (2). The plug-in end (501) contracts smoothly toward the contraction end (502), and the contraction direction is toward the horizontal opening direction of the clamping mouth (4).

3. The chuck for a high-strength fatigue testing machine for a step chain according to claim 2, characterized in that: Two spring leaves (11) are fixedly installed at the bottom of the rotating plate (8), and the two spring leaves (11) are respectively located on the outside of the two clamping plates (3). The spring leaves (11) are "V"-shaped, and one end of the spring leaf (11) is a fixed end (12), and the fixed end (12) is fixedly connected to the bottom of the rotating plate (8). The other end of the spring leaf (11) is a free end (13). The spring leaf (11) is used to squeeze the end of the connecting pin shaft (2) extending out of the clamping mouth (4) when the rotating plate (8) rotates downward, and to push the connecting pin shaft (2) horizontally from the plug-in end (501) toward the retracted end (502).

4. The chuck for a high-strength fatigue testing machine for a step chain according to claim 1, characterized in that: The convex block (10) is an isosceles trapezoid, the upper base length of the convex block (10) of the isosceles trapezoid is greater than the lower base length, and the waist of the isosceles trapezoid faces the direction of the boss (7).

5. The chuck for a high-strength fatigue testing machine for a step chain according to claim 4, characterized in that: A hard layer (14) is provided on the plane of the protrusion (10) facing the boss (7), the hard layer (14) is made of rubber material, and anti-slip patterns (15) are also provided on the hard layer (14).

6. The chuck for a high-strength fatigue testing machine for a step chain according to claim 4, characterized in that: A base plate (16) is fixedly mounted on the bottom of the clamping plate (3), and the base plate (16) fixedly connects the two clamping plates (3) and the clamp body (1) together.

7. The chuck for a high-strength fatigue testing machine for a step chain according to claim 6, characterized in that: An elastic plate (17) is fixedly mounted on the top surface of the bottom plate (16), the elastic plate (17) is parallel to the waist of the protrusion (10) on the side away from the boss (7), a slot (18) is provided on the plane of the protrusion (10) on the side away from the boss (7), and a hook portion (19) for being inserted into the slot (18) is provided on the top of the elastic plate (17).

8. The chuck for a high-strength fatigue testing machine for a step chain according to claim 7, characterized in that: A countersunk hole (20) is provided at the top of the rotating plate (8), and the countersunk hole (20) is perpendicular to the top surface of the rotating plate (8) and passes through the rotating plate (8). An unlocking rod (21) is slidably installed inside the countersunk hole (20). The top of the elastic plate (17) is extended to the bottom of the countersunk hole (20) to form an extension portion (22). A spring (23) is also provided inside the countersunk hole (20), and the spring (23) is used to keep the unlocking rod (21) pushed upward.

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