Top clamping type sample clamp device for testing fatigue performance of metal sample and use method of top clamping type sample clamp device

Abstract

The invention provides a top clamping type sample clamp device for testing the fatigue performance of a metal sample and a using method, the top clamping type sample clamp device comprises a fatigue testing machine body, and clamping type sample clamp devices are oppositely arranged at the top of a fatigue testing machine high-frequency generator and the bottom of a fatigue testing machine base respectively; the clamping type sample clamp device comprises a hollow main shaft, a top table, a sliding clamp, a main shaft fastening disc and an anti-loosening tension spring. The clamp is simple in installation mode, and the installation precision is easy to control; the problems that a thread is difficult to process on a high-strength sample and the thread of a low-strength sample is easy to damage to cause detection failure are well solved; the direction of the load applied to the sample by the clamp is the same as that of the test load of the sample without depending on the friction force generated by the clamping force, so that stable pressure and tension can be effectively provided in the whole experiment process; the clamp is wide in application range, can be suitable for samples of different sizes by changing the sizes of the hoop and the top table in a matched mode, and can also be used for clamping samples in high and low temperature environments.

Description

Technical Field

[0001] The invention relates to the technical field of fatigue mechanical properties testing of metal samples, and in particular to a top clamp type sample fixture device for fatigue properties testing of metal samples and a use method thereof. Background Art

[0002] The destruction of metal parts is mainly caused by fatigue failure, so the detection and analysis of the fatigue resistance of metal materials is particularly important. As fatigue detection equipment, it contains many functional units to control the parameters of fatigue testing and complete the detection process that meets national or international standards. The technical development of these functional units is relatively mature, but the fixtures that are in direct contact with the tested samples have been neglected, and there is a lack of technical solutions. At present, the metal material fatigue testing equipment publicly sold on the market widely uses two sample clamping solutions, one is a low-cost threaded connection clamping method, and the other is a high-cost hydraulic automatic clamping method. Both clamping solutions have some problems and limitations.

[0003] There are several problems with the method of connecting equipment and specimens using threaded connections: (1) The specimen is required to have a high processing accuracy, otherwise it cannot be connected to the equipment fixture. For materials with higher hardness, it is difficult to process threads without changing the material properties. (2) Because of the need to screw, there must be a gap between the specimen thread and the equipment fixture, which poses a risk of loosening. (3) For materials with lower hardness, due to the low material strength, the connection strength that the thread can provide is limited, and it is very easy to be damaged and loose, resulting in inaccurate test results.

[0004] In addition to the high cost and complex structure, the hydraulic clamping solution also has several problems. (1) For materials with higher hardness, it is difficult for the hydraulic chuck to make a notch. The friction between the clamp and the sample may not be able to resist the axial force of the test, causing the sample and the chuck to slide, affecting the test results. (2) For materials with lower hardness, the hydraulic clamping force needs to be finely adjusted. It should not cause large deformation of the material and affect the performance of the specimen, but also provide a large enough clamping force to prevent the specimen from sliding during the test. In view of the limitations of existing solutions on the market, some patent technologies are trying to solve some of the problems. A patent with the authorization number CN105527157B proposes a quick-loading and unloading split-type fixture, which has the characteristics of quick loading and unloading and self-adaptation in centering. However, due to the use of a pin-hanging structure and the installation characteristics of the parts, only tensile fatigue or zero fatigue can be applied. If compressive stress occurs, it will cause parts to loosen and misaligned. A patent with the authorization number CN115389312B proposes a fatigue fixture for use under high temperature conditions, which can also serve as a reference for use at room temperature, but its structure can only be used for plate-like samples, and its structure is no different from the mature threaded push wedge fixture in the market. It is not easy to ensure the flatness of the upper and lower clamping ends during the installation and testing process, resulting in distortion and instability during the fatigue test.

[0005] In summary, the existing technical solutions are not sufficient to better solve the clamping problem of high-strength and low-strength rod-shaped fatigue samples. Summary of the invention

[0006] In order to make up for the shortcomings of the prior art, the present invention provides a top clamping sample fixture device and a method of use for fatigue performance testing of metal specimens, which solves the problems of complex structure, narrow application range of materials, difficult to ensure clamping force, and complex operation of traditional clamping solutions. It mainly includes: (1) The threaded connection method of traditional fatigue samples is easy to loosen during fatigue testing; (2) The application range of traditional threaded connection materials is narrow. For high-hardness materials, the threads are difficult to process. For low-hardness materials, the threaded connection strength is weak and easily damaged. Traditional hydraulic clamping methods often cause deformation of the clamps of low-strength materials, affecting test results.

[0007] The present invention is realized through the following technical scheme: a top clamping sample fixture device for fatigue performance testing of metal specimens, comprising a fatigue testing machine body, the fatigue testing machine body comprising a fatigue testing machine base and a fatigue testing machine crossbeam, the fatigue testing machine base and the left and right ends of the fatigue testing machine crossbeam are movably connected through a fatigue testing machine lead screw and a fatigue testing machine slide rail, a fatigue testing machine high-frequency generator is arranged at the center position of the lower surface of the fatigue testing machine crossbeam, a clamping sample fixture device is arranged oppositely at the top of the fatigue testing machine high-frequency generator and the bottom of the fatigue testing machine base, the clamping sample fixture device comprises a hollow main shaft, a top platform, a sliding clamp, a main shaft fastening disk and an anti-loosening tension spring, an outer gear ring is arranged on the outer wall of the main shaft fastening disk, a mounting cap is fixed at the center position of one side of the main shaft fastening disk, and the main shaft fastening disk is fixed by mounting The lower inner circumferential thread in the mounting cap is connected with the outer thread of the main shaft fixed on the fatigue testing machine base and the high-frequency generator of the fatigue testing machine. The upper inner diameter of the mounting cap of the main shaft fastening plate has an inclined surface and gradually decreases. The sliding clamp is a two-half structure and is arranged on the upper part of the main shaft fastening plate. The upper outer wall of the sliding clamp is an inclined surface, and the lower part of the top platform is placed in the main shaft. The lower part of the sliding clamp is a sliding guide groove, and the top of the top platform is a raised additional guide rail located in the sliding guide groove of the sliding clamp. The left and right sides of the additional guide rail are fixedly installed with a slot, and the top of the main shaft is fixedly installed with a limit block matching the slot, the upper part of the sliding clamp is a clamping end, and the inner wall at the top of the clamping end is an arc surface; one end of the anti-loosening tension spring is fixed by an anti-loosening tension spring bolt, and the other end of the anti-loosening tension spring is hooked on the teeth of the outer gear ring of the main shaft fastening plate.

[0008] As a preferred solution, the depth of the clamping end of the sliding clamp is smaller than the length of the clamping parallel section of the sample to be tested.

[0009] As a preferred solution, the depth of the sliding guide groove of the sliding clamp is greater than the height of the additional guide rail of the top platform.

[0010] As a preferred solution, the top table is magnetized.

[0011] A method for using a top clamp type sample fixture device for fatigue performance testing of a metal sample specifically comprises the following steps: Step 1: First, clamp the clamping end of the sample to be tested, and adsorb the magnetic top table to the main shaft of the fatigue testing machine beam, so that the slot of the additional guide rail of the top table is clamped to the limit block on the main shaft; Step 2: Place the sample to be tested between the two halves of the sliding clamps, pinch the two halves of the sliding clamps to make the sample to be tested vertical. The sample to be tested should fall freely under the action of gravity and combine with the sliding clamps at the transition arc position of the sample to be tested. If this cannot be achieved, it means that the sample size exceeds the tolerance; Step 3: Place the spindle fastening plate on the bracket with the large opening facing upwards, ensuring that there is reserved space under the fastening plate; Step 4. Pinch the two sliding clamps that clamp the sample to be tested, with the sample facing downward and the sliding clamp facing upward. Put the two sliding clamps and the sample into the spindle fastening plate. The outer bevel of the sliding clamp matches the inner bevel of the spindle fastening plate and slides freely. Confirm that the sample to be tested is in the position of the sliding clamp, so that it only fits at the transition arc and keeps a gap in other places. Confirm that the sliding clamp slides to the bottom in the spindle fastening plate, and the outer bevel of the sliding clamp fits tightly with the inner bevel of the spindle fastening plate. Confirm that the clamping end of the sample is exposed from the sliding clamp; Step 5: Screw the spindle fastening plate with the large opening facing upwards, together with the placed sliding clamp and the sample to be tested, onto the upper spindle thread, and gradually tighten it so that the top platform supports the clamping end of the sample; Step 6: Use a toothed wrench to further tighten the sample through the outer gear ring of the spindle fastening plate; Step 7: Fix one end of the anti-loosening tension spring on the anti-loosening tension spring bolt, and hook the other end on the teeth of the outer gear ring of the spindle fastening plate, so that the spindle fastening plate generates a tightening force in the same direction as the wrench loading, so as to loosen the spindle fastening plate; Step 8: Start clamping the lower clamping end of the sample to be tested by first placing the top table on the main shaft of the fatigue testing machine base; Step 9: Put the two sliding clamps together and place them on the top platform, so that the sliding guide groove of the sliding clamp matches with the additional guide rail of the top platform, and check and confirm the gap between the guide groove and the guide rail; Step 10: Pre-install the spindle fastening plate into the spindle thread and screw it in about 5mm; Step 11: Use a simple pick to separate the two halves of the sliding clamp and stick the inclined surfaces of the sliding clamp together; Step 12: Zero the sensor of the fatigue testing machine and switch the crossbeam movement mode to manual mode; Step 13: According to the different positions of the crossbeam of the fatigue testing machine, slowly lower the crossbeam of the fatigue testing machine so that the tested sample slowly enters the middle of the two separated sliding clamps; Step 14: When the lower clamping end of the tested sample approaches the top table, slowly move the crossbeam of the fatigue testing machine and observe the reading of the mechanical sensor. When the clamping end of the sample contacts the top table, stop moving, observe the reading of the mechanical sensor, and continue to move the crossbeam using manual fine-tuning. Stop when the clamping pressure is less than half of the yield strength of the material. Step 15: Move the two halves of the sliding clamp to close the sliding clamp and fit it tightly against the clamping end of the sample being tested; Step 16: Tighten the main shaft fastening plate of the fatigue testing machine base so that the inner inclined surface of the main shaft fastening plate fits tightly with the outer inclined surface of the sliding clamp, and use a toothed wrench to further tighten the clamping of the sample through the outer gear ring of the sliding clamp; Step 17: Hook the anti-loosening tension spring. The hooking method is the same as the anti-loosening spring requirements of the main shaft fastening plate of the fatigue testing machine crossbeam; Step 18: Use the manual fine-tuning method of the fatigue testing machine beam to unload the top force to about 0N; Step 19: The movement mode of the fatigue testing machine crossbeam (11) is adjusted to the software control mode.

[0012] Due to the adoption of the above technical solution, the present invention has the following beneficial effects compared with the prior art: (1) Compared with the threaded fixture sample installation method, this fixture installation method is simple and easy to control the installation accuracy; (2) It effectively solves the problem that high-strength samples are difficult to process threads, and low-strength samples are prone to damage, resulting in test failure; (3) Compared with hydraulic chucks, the cost of the chuck of the present invention is low, and the tension spring structure makes it easy to control the degree of clamping tightness; (4) Compared with the hydraulic chuck, the load applied to the sample by the clamp of the present invention is in the same direction as the sample test load, and does not rely on the friction force generated by the clamping force, which can effectively ensure that stable pressure and tension are provided throughout the experiment; (5) This clamp has a wide range of applications. By changing the size of the clamp and the top platform, it can be used for specimens of different sizes. It can also be used to clamp specimens in high and low temperature environments.

[0013] Additional aspects and advantages of the present invention will become apparent from the following description or may be learned by practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] The above and / or additional aspects and advantages of the present invention will become apparent and easily understood from the description of the embodiments in conjunction with the following drawings, in which: Figure 1 This is a schematic diagram of the exploded structure of the sample parts of the card-type sample fixture device; Figure 2 This is a schematic diagram of the force applied to the sample clamping state of the card-type sample fixture; Figure 3 This is the installation position diagram of the top card sample fixture device of the fatigue test machine and the partial enlarged diagram; Figure 4 This is a partial enlarged view of the parts position before clamping of the card-type sample fixture; Figure 5 This is a schematic diagram of a single-sided card sample fixture clamping a sample; Figure 6 This is a schematic diagram of a double-sided card sample fixture clamping a sample; Figure 7 This is a partial enlarged view of the double-sided sample clamp clamping the sample top position, hiding the upper spindle fastening plate and the right half of the sliding clamp. in, Figures 1 to 7 The corresponding relationship between the reference numerals and the components is as follows: (1) Spindle; (2) Top platform; (3) Sliding clamp; (4) Spindle fastening plate; (5) Test sample; (6) Anti-loosening tension spring; (7) Anti-loosening tension spring bolt; (8) Fatigue testing machine base; (9) Fatigue testing machine lead screw; (10) Fatigue testing machine slide rail; (11) Fatigue testing machine crossbeam; (12) Fatigue testing machine high frequency generator. DETAILED DESCRIPTION

[0015] In order to more clearly understand the above-mentioned purpose, features and advantages of the present invention, the present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments. It should be noted that the embodiments of the present application and the features in the embodiments can be combined with each other without conflict.

[0016] In the following description, many specific details are set forth to facilitate a full understanding of the present invention. However, the present invention may also be implemented in other ways different from those described herein. Therefore, the protection scope of the present invention is not limited to the specific embodiments disclosed below.

[0017] Combine the following Figures 1 to 7 The top clamp type sample fixture device for fatigue performance testing of metal specimens according to the embodiment of the present invention and the use method thereof are specifically described.

[0018] The present invention provides a top clamp type sample fixture device for testing fatigue properties of metal samples, as shown in the attached Figure 1 As shown, the fatigue testing machine includes a fatigue testing machine body, which includes a fatigue testing machine base 8 and a fatigue testing machine cross beam 11. The fatigue testing machine base 8 and the left and right ends of the fatigue testing machine cross beam 11 are movably connected through a fatigue testing machine lead screw 9 and a fatigue testing machine slide rail 10. A fatigue testing machine high-frequency generator 12 is arranged at the center of the lower surface of the fatigue testing machine cross beam 11. The top of the fatigue testing machine high-frequency generator 12 and the bottom of the fatigue testing machine base 8 are respectively arranged with a card-type sample clamp device, as shown in the attached Figure 1As shown, the card-type sample clamp device includes a hollow main shaft 1, a top platform 2, a sliding clamp 3, a main shaft fastening disk 4 and an anti-loosening tension spring 6. An external gear ring is arranged on the outer wall of the main shaft fastening disk 4. A mounting cap is fixed at the center position of one side of the main shaft fastening disk 4. The main shaft fastening disk 4 is connected with the external thread of the main shaft 1 fixed on the fatigue testing machine base 8 and the high-frequency generator 12 of the fatigue testing machine through the lower inner circumferential thread in the mounting cap. The upper inner diameter of the mounting cap of the main shaft fastening disk 4 has an inclined surface and gradually decreases. The sliding clamp 3 is a two-half structure, which is arranged on the upper part of the main shaft fastening disk 4. The upper outer wall of the sliding clamp 3 is an inclined surface. When the main shaft fastening disk 4 is loosened, the two halves of the sliding clamp 3 can be opened to facilitate the loading of the sample. When the main shaft fastening disk 4 is tightened, the sliding clamp 3 has an inclined surface combined with the main shaft fastening disk 4, and the two halves of the sliding clamp 3 are closed. The top of the top platform 2 is placed in the main shaft 1, and the lower part of the sliding clamp 3 is a sliding guide groove. The top of the top platform 2 is a raised additional guide rail located in the sliding guide groove of the sliding clamp 3, which is used to support the tested sample, so that the main shaft fastening plate 4 drives the sliding clamp 3 to pull the sample, and the top platform 2 supports the sample at the other end, and fixes the sample between the top platform 2 and the sliding clamp 3 to realize the loading of tensile stress and compressive stress. The left and right sides of the additional guide rail are fixedly installed with a clamping groove 13, and the top of the main shaft 1 is fixedly installed with a limit block 14 matching the clamping groove 13. The upper part of the sliding clamp 3 is the clamping end, and the inner wall at the top of the clamping end is an arc surface; one end of the anti-loosening tension spring 6 is fixed by the anti-loosening tension spring bolt 7, and the other end of the anti-loosening tension spring 6 is hooked on the teeth of the outer gear ring of the main shaft fastening plate 4. The anti-loosening tension spring is fixed on the gear teeth of the main shaft fastening disk 4 and the equipment anti-loosening tension spring bolt 7, and is used to provide a pre-tightening force to the main shaft fastening disk 4.

[0019] Under the fixing action of the card sample fixture device, the force on the clamping part of the sample to be tested is as follows: Figure 3 As shown. The spindle fastening disk is connected to the spindle. The spindle fastening disk is rotated. Under the action of the thread, the spindle fastening disk moves downward①; the spindle fastening disk applies a lateral push to the sliding clamp through the inclined surface. When the sliding clamp is closed, the spindle fastening disk applies pressure to the sliding clamp②; the arc surface of the sliding clamp presses on the arc segment of the tested specimen, applying downward pressure to the tested fatigue specimen③; the top platform placed on the spindle forms a support for the clamping end of the tested specimen④; the sample is fixed between the spindle and the sliding clamp.

[0020] There is a gap between the sliding clamp 3 and the vertical surface of the sample 5 to be tested, and the arc part is the fixed end to ensure the transmission of force; the clamping end depth of the sliding clamp 3 should be less than the length of the clamping parallel section of the sample to be tested, so that the clamping end of the sample is exposed for about 5mm, so that the top platform 2 can support the clamping end of the sample and fix the sample. The depth of the sliding guide groove of the sliding clamp 3 is greater than the height of the additional guide rail of the top platform 2 to prevent the clamp from pressing the top platform. The depth of the top platform 2 embedded in the spindle 1 should be reasonable to prevent the additional guide rail of the top platform from pressing the end face of the spindle; for easy installation, the top platform 2 used for the upper spindle is magnetized.

[0021] A method for using a top clamping sample fixture for fatigue performance testing of a metal sample, specifically comprising the following steps: For a device clamped in a vertical direction, the fixture described in the technical solution is most suitable for first clamping the upper half, and in conjunction with a fatigue testing machine, the operation method of the fixture described in the technical solution during the fatigue testing process is as follows: Step 1: First, clamp the clamping end of the sample to be tested, and adsorb the magnetic top platform 2 on the main shaft 1 of the fatigue testing machine crossbeam 11, so that the slot 13 of the additional guide rail of the top platform 2 is clamped on the limit block 14 on the main shaft, and make sure that the top platform has sufficient adsorption force and will not fall, and check whether the gap above and below the additional guide rail of the top platform is appropriate; Step 2: Place the sample 5 to be tested between the two half sliding clamps 3, pinch the two half sliding clamps 3 to make the sample to be tested vertical. The sample to be tested should fall freely under the action of gravity and combine with the sliding clamp 3 at the transition arc position of the sample to be tested. If this cannot be achieved, it means that the sample size exceeds the tolerance and should be processed in time; Step 3: Place the spindle fastening plate 4 on the bracket with the large opening facing upwards, ensuring that there is reserved space under the fastening plate; Step 4: Pinch the two sliding clamps 3 that clamp the sample to be tested, with the sample to be tested facing downward and the sliding clamps 3 facing upward. Put the two sliding clamps 3 and the sample into the spindle fastening disk 4 together. The outer bevel of the sliding clamp 3 matches the inner bevel of the spindle fastening disk 4 and slides freely. Confirm that the sample to be tested is in the position of the sliding clamp 3, so that it only fits at the transition arc and keeps a certain gap in other places. Confirm that the sliding clamp 3 slides to the bottom in the spindle fastening disk 4, and the outer bevel of the sliding clamp 3 fits tightly with the inner bevel of the spindle fastening disk 4. Confirm that the clamping end of the sample is exposed to a certain height of the sliding clamp 3 platform so that the top platform 2 can support it. Step 5: Screw the spindle fastening plate 4 with the large opening facing upward, together with the placed sliding clamp 3 and the sample to be tested, onto the upper spindle thread, and gradually tighten it so that the top platform 2 supports the clamping end of the sample; Step 6: Use a toothed wrench to further tighten the sample through the outer gear ring of the spindle fastening plate 4; Step 7: Fix one end of the anti-loosening tension spring 6 on the anti-loosening tension spring bolt 7, and hook the other end on the teeth of the outer gear ring of the spindle fastening plate 4, so that the spindle fastening plate 4 generates a fastening force in the same direction as the wrench loading, so that the spindle fastening plate 4 is loosened; Step 8: Start clamping the lower clamping end of the sample to be tested. First, place the top table 2 on the main shaft 1 of the fatigue testing machine base 8. Pay attention to the coordination of the limit position. The clearance requirement is the same as that of the top table. Step 9: Combine the two sliding clamps 3 and place them on the top platform 2, so that the sliding guide groove of the sliding clamp 3 matches with the additional guide rail of the top platform 2, and check and confirm the gap between the guide groove and the guide rail; Step 10: Pre-install the spindle fastening plate 4 into the spindle thread and screw it in about 5mm; Step 11: Use a simple pick to separate the two halves of the sliding clamp 3, and stick the inclined surfaces of the sliding clamp 3 on each other; Step 12: Zero the sensor of the fatigue testing machine and switch the crossbeam movement mode to manual mode to move the crossbeam and determine whether the top table is supporting the sample; Step 13: According to the different positions of the crossbeam 11 of the fatigue testing machine, slowly lower the crossbeam 11 of the fatigue testing machine, or raise the lower crossbeam of the testing machine, so that the tested sample slowly enters the middle of the two separated sliding clamps 3. Pay attention to the mechanical sensor during the movement of the crossbeam to avoid the sample from hitting the top platform; Step 14: When the lower clamping end of the tested sample approaches the top platform 2, slowly move the fatigue testing machine beam 11 while observing the mechanical sensor reading. Stop moving when the sample clamping end contacts the top platform, observe the mechanical sensor reading, and continue to move the beam using manual fine-tuning. Stop when the mechanical sensor reading is about 100N. 100N is a generally recommended value. Set different tightening forces according to the strength of the tested sample, but make sure to stop when the tightening pressure is less than half of the material yield strength. Step 15, move the two halves of the sliding clamp 3 to close the sliding clamp 3 and close it to the clamping end of the sample to be tested; Step 16, tighten the spindle fastening plate 4 of the fatigue testing machine base 8, so that the inner inclined surface of the spindle fastening plate 4 is tightly fitted with the outer inclined surface of the sliding clamp 3, and use a toothed wrench to further tighten the clamping of the sample through the outer gear ring of the sliding clamp 3; Step 17, hook the anti-loosening tension spring 6, the hooking method is the same as the anti-loosening spring 6 of the main shaft fastening plate 4 of the fatigue testing machine crossbeam 11; Step 18, use the manual fine adjustment method of the fatigue testing machine beam 11 to unload the top tightening force to about 0N; Step 19: Adjust the movement mode of the fatigue testing machine beam 11 to the software control mode.

[0022] At this point, the operation of clamping the fatigue sample of the tensile and compressive fatigue test sample using the clamp scheme described in the present invention is completely completed. If a tensile fatigue test or a zero-tensile fatigue test is performed, the use of the top table can be omitted. In order to ensure the clamping effect of this scheme, the size of the sample clamping part needs to be designed in accordance with the size of the clamp described in this scheme to ensure that the gap between each part is correct and the correct loading of tension and pressure is achieved.

[0023] At this point, you can proceed to setting the fatigue test parameters. This part of the operation has nothing to do with the type or scheme of the fixture. It includes setting the maximum and minimum loads according to the cross-sectional area of ​​the sample and the preloaded stress; setting the fatigue loading frequency as needed; setting the preload speed of the sample before starting fatigue; setting the end condition of fatigue to fracture, or rated life end; if it is a stage fatigue test, it is also necessary to set the fatigue loading spectrum; after the settings are completed, start the fatigue testing machine to start the fatigue test.

[0024] At this point, the operation of clamping the fatigue sample of the tensile and compressive fatigue test sample using the clamp scheme described in the present invention is completely completed. If a tensile fatigue test or a zero-tensile fatigue test is performed, the use of the top table can be omitted. In order to ensure the clamping effect of this scheme, the size of the sample clamping part needs to be designed in accordance with the size of the clamp described in this scheme to ensure that the gap between each part is correct and the correct loading of tension and pressure is achieved.

[0025] At this point, you can proceed to setting the fatigue test parameters. This part of the operation has nothing to do with the type or scheme of the fixture. It includes setting the maximum and minimum loads according to the cross-sectional area of ​​the sample and the preloaded stress; setting the fatigue loading frequency as needed; setting the preload speed of the sample before starting fatigue; setting the end condition of fatigue to fracture, or rated life end; if it is a stage fatigue test, it is also necessary to set the fatigue loading spectrum; after the settings are completed, start the fatigue testing machine to start the fatigue test.

[0026] In the description of the present invention, the term "plurality" refers to two or more than two. Unless otherwise clearly defined, the orientation or positional relationship indicated by the terms "upper" and "lower" is based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the present invention and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, it cannot be understood as a limitation of the present invention; the terms "connection", "installation", "fixation", etc. should be understood in a broad sense. For example, "connection" can be a fixed connection, a detachable connection, or an integral connection; it can be directly connected or indirectly connected through an intermediate medium. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0027] In the description of this specification, the description of the terms "one embodiment", "some embodiments", "specific embodiments", etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0028] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A top-clamping sample fixture device for fatigue performance testing of a metal sample, comprising a fatigue testing machine body, the fatigue testing machine body comprising a fatigue testing machine base (8) and a fatigue testing machine crossbeam (11), the fatigue testing machine base (8) and the fatigue testing machine crossbeam (11) are movably connected at both ends through a fatigue testing machine lead screw (9) and a fatigue testing machine slide rail (10), a fatigue testing machine high-frequency generator (12) is arranged at the center of the lower surface of the fatigue testing machine crossbeam (11), characterized in that The top of the fatigue testing machine high-frequency generator (12) and the bottom of the fatigue testing machine base (8) are respectively provided with a card-type sample clamp device, the card-type sample clamp device comprising a hollow main shaft (1), a top platform (2), a sliding clamp (3), a main shaft fastening plate (4) and an anti-loosening tension spring (6), an outer gear ring is provided on the outer wall of the main shaft fastening plate (4), a mounting cap is fixed at the center position of one side of the main shaft fastening plate (4), the main shaft fastening plate (4) is connected to the external thread of the main shaft (1) fixed on the fatigue testing machine base (8) and the fatigue testing machine high-frequency generator (12) through the lower inner peripheral thread in the mounting cap, the inner upper diameter of the main shaft fastening plate (4) has an inclined surface and gradually decreases, the sliding clamp (3) is two The semi-structure is arranged on the upper part of the main shaft fastening plate (4), the upper outer wall of the sliding clamp (3) is an inclined surface, the lower part of the top platform (2) is placed in the main shaft (1), the lower part of the sliding clamp (3) is a sliding guide groove, the top of the top platform (2) is a raised additional guide rail located in the sliding guide groove of the sliding clamp (3), the left and right sides of the additional guide rail are fixedly installed with a clamping groove (13), the top of the main shaft (1) is fixedly installed with a limit block (14) matching the clamping groove (13), the upper part of the sliding clamp (3) is a clamping end, and the inner wall at the top of the clamping end is an arc surface; one end of the anti-loosening tension spring (6) is fixed by an anti-loosening tension spring bolt (7), and the other end of the anti-loosening tension spring (6) is hooked on the teeth of the outer gear ring of the main shaft fastening plate (4).

2. A top clamp type sample fixture device for fatigue performance testing of metal specimens and a method of use according to claim 1, characterized in that The depth of the clamping end of the sliding clamp (3) is smaller than the length of the clamping parallel section of the sample to be tested.

3. A top clamp type sample fixture device for fatigue performance testing of metal specimens according to claim 1, characterized in that The depth of the sliding guide groove of the sliding clamp (3) is greater than the height of the additional guide rail of the top platform (2).

4. A top clamp type sample fixture device for fatigue performance testing of metal specimens according to claim 1, characterized in that , the top platform (2) is magnetized.

5. A method for using a top clamp type sample fixture for fatigue performance testing of a metal sample as described in claims 1 to 4, characterized in that , specifically including the following steps: Step 1: First, clamp the clamping end of the sample to be tested, and adsorb the magnetic top platform (2) on the main shaft (1) of the fatigue testing machine crossbeam (11), so that the slot of the additional guide rail of the top platform (2) is clamped to the limit block on the main shaft; Step 2: Place the sample to be tested between the two halves of the sliding clamp (3), pinch the two halves of the sliding clamp (3) to make the sample to be tested vertical. The sample to be tested should fall freely under the action of gravity and combine with the sliding clamp (3) at the transition arc position of the sample to be tested. If this cannot be achieved, it means that the sample size exceeds the tolerance. Step 3. Place the spindle fastening plate (4) on the bracket with the large opening facing upwards, ensuring that there is space reserved underneath the fastening plate. Step 4: Pinch the two sliding clamps (3) that clamp the sample to be tested, with the sample to be tested facing downward and the sliding clamps (3) facing upward. Place the two sliding clamps (3) and the sample together into the spindle fastening plate (4). The outer bevel of the sliding clamp (3) fits with the inner bevel of the spindle fastening plate (4) and slides freely. Confirm that the sample to be tested is in the position of the sliding clamp (3), so that it only fits at the transition arc and maintains a gap at other places. Confirm that the sliding clamp (3) slides to the bottom in the spindle fastening plate (4), and the outer bevel of the sliding clamp (3) fits tightly with the inner bevel of the spindle fastening plate (4). Confirm that the clamping end of the sample is exposed from the sliding clamp (3); Step 5: Screw the spindle fastening plate (4) with the large opening facing upward, together with the placed sliding clamp (3) and the sample to be tested, onto the upper spindle thread, and gradually tighten it so that the top platform (2) supports the clamping end of the sample; Step 6: Use a toothed wrench to further tighten the sample through the outer gear ring of the spindle clamping plate (4); Step 7: Fix one end of the anti-loosening tension spring (6) on the anti-loosening tension spring bolt (7) and hook the other end on the teeth of the outer gear ring of the spindle fastening plate (4), so that the spindle fastening plate (4) generates a tightening force in the same direction as the wrench load, so that the spindle fastening plate (4) is loosened; Step 8, start clamping the lower clamping end of the sample to be tested, first place the top table (2) on the main shaft (1) of the fatigue testing machine base (8); Step 9: Combine the two sliding clamps (3) and place them on the top platform (2), so that the sliding guide groove of the sliding clamp (3) matches with the additional guide rail of the top platform (2), and check and confirm the gap between the guide groove and the guide rail; Step 10. Pre-install the spindle fastening plate (4) into the spindle thread and screw it in about 5mm. Step 11: Use a simple pick to separate the two halves of the sliding clamp (3) and attach the inclined surfaces of the sliding clamp (3) respectively; Step 12: Zero the sensor of the fatigue testing machine and switch the crossbeam movement mode to manual mode; Step 13, according to the different positions of the fatigue testing machine crossbeam (11), slowly lower the fatigue testing machine crossbeam (11) so that the tested sample slowly enters the middle of the two separated sliding clamps (3); Step 14, when the lower clamping end of the sample to be tested approaches the top platform (2), slowly move the crossbeam (11) of the fatigue testing machine while observing the reading of the mechanical sensor. When the clamping end of the sample contacts the top platform, stop moving, observe the reading of the mechanical sensor, continue to move the crossbeam using manual fine adjustment, and stop when the clamping pressure is less than half of the yield strength of the material. Step 15, move the two halves of the sliding clamp (3) to close the sliding clamp (3) and make it close to the clamping end of the sample to be tested; Step 16, tighten the spindle fastening plate (4) of the fatigue testing machine base (8) so that the inner inclined surface of the spindle fastening plate (4) is tightly fitted with the outer inclined surface of the sliding clamp (3), and use a toothed wrench to further tighten the clamping of the sample through the outer gear ring of the sliding clamp (3); Step 17, hook the anti-loosening tension spring (6), and the hooking method is the same as the anti-loosening spring (6) of the main shaft fastening plate (4) of the fatigue testing machine crossbeam (11); Step 18: Use the manual fine adjustment method of the fatigue testing machine beam (11) to unload the tightening force to about 0N; Step 19: The movement mode of the fatigue testing machine crossbeam (11) is adjusted to the software control mode.

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