A top-clip sample fixture device for fatigue performance testing of metal specimens and its use method

Abstract

The present invention provides a top-clip sample fixture device for fatigue performance testing of metal specimens and a method for use, comprising a fatigue testing machine body, a top of the high-frequency generator of the fatigue testing machine, and a card-type sample fixture device respectively arranged opposite to each other on the bottom of the fatigue testing machine base, the card-type sample fixture device comprising a hollow main shaft, a top platform, a sliding clamp, a main shaft fastening disk, and an anti-loosening tension spring. This fixture is simple to install and easy to control the installation accuracy; it effectively solves the problem that high-strength specimens are difficult to process threads, and low-strength specimens are prone to damage, resulting in test failure; the load applied to the sample by the fixture of this technical invention is in the same direction as the sample test load, does not rely on the friction generated by the clamping force, and can effectively ensure that stable pressure and tension are provided throughout the experiment; this fixture has a wide range of applications. By matching and changing the size of the clamp and the top platform, it can be used for specimens of different sizes, and can also be used to clamp specimens in high and low temperature environments.

Description

Technical Field

[0001] The present invention relates to the technical field of fatigue mechanical property testing of metal samples, and in particular to a top-clamping sample clamp device for fatigue property 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 testing equipment, it contains numerous functional units to control the parameters of fatigue testing and complete the testing 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 technical solutions are scarce. At present, two specimen clamping solutions are widely used in metal material fatigue testing equipment publicly sold on the market. 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 using threaded connection equipment and specimens: (1) The specimen must have 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 hidden danger 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 clamp out notches. 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 size of 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 characteristics, but also provide sufficient clamping force to prevent the specimen from sliding during the test.

[0005] In response to the limitations of existing solutions on the market, some patented technologies are attempting to address some of the problems. A patent with 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 misalignment. A patent with 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. However, its structure can only be used for plate-shaped samples, and its structure is essentially the same as the mature threaded push wedge fixture on the market. It is not easy to ensure the flatness of the upper and lower clamping ends during installation and testing, resulting in distortion and instability during fatigue testing.

[0006] In short, 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

[0007] To address the shortcomings of the existing technology, the present invention provides a top-clip sample clamp device and method for use in fatigue performance testing of metal specimens, addressing the problems of traditional clamping solutions, such as complex structure, narrow material applicability, difficulty in ensuring clamping force, and complex operation. The present invention mainly includes:

[0008] (1) The threaded connection method of traditional fatigue specimens is prone to loosening during fatigue testing;

[0009] (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 prone to damage.

[0010] Traditional hydraulic clamping methods often cause deformation of the clamping head of low-strength materials, affecting test results.

[0011] The present invention is realized through the following technical scheme: a top-clip sample clamp 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 by a fatigue testing machine lead screw and a fatigue testing machine slide rail, a fatigue testing machine high-frequency generator is provided at the center position of the lower surface of the fatigue testing machine crossbeam, a card-type sample clamp device is respectively provided at the top of the fatigue testing machine high-frequency generator and the bottom of the fatigue testing machine base, the card-type sample clamp 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 provided 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 to the external thread of the main shaft fixed on the fatigue testing machine base and the fatigue testing machine high-frequency generator. 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, 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, and the lower part of the sliding clamp is a sliding guide groove. 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 spring is fixed by an anti-loosening spring bolt, and the other end of the anti-loosening spring is hooked on the teeth of the outer gear ring of the main shaft fastening plate.

[0012] 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.

[0013] 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.

[0014] As a preferred solution, the top platform is magnetized.

[0015] A method for using a top-clamping sample fixture for fatigue performance testing of a metal specimen comprises the following steps:

[0016] Step 1: First, clamp the upper clamping end of the sample to be tested, and adsorb the magnetic top platform to the main shaft of the fatigue testing machine beam, so that the slot of the top platform's additional guide rail is stuck in the limit block on the main shaft;

[0017] 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;

[0018] Step 3: Place the spindle fastening plate on the bracket with the large opening facing upwards, ensuring there is space reserved underneath the fastening plate;

[0019] Step 4: Pinch the two sliding clamps that hold the sample to be tested, with the sample facing downward and the sliding clamps facing upward. Place the two sliding clamps and the sample into the spindle fastening disk. The outer bevel of the sliding clamps fits with the inner bevel of the spindle fastening disk and slides freely. Confirm that the sample to be tested is in the position of the sliding clamps, so that it fits only at the transition arc and maintains a gap at other places. Confirm that the sliding clamps slide to the bottom in the spindle fastening disk, and the outer bevel of the sliding clamps fits tightly with the inner bevel of the spindle fastening disk. Confirm that the clamping end of the sample is exposed from the sliding clamps.

[0020] Step 5: With the main shaft fastening plate facing upwards, screw it onto the upper main shaft thread along with the placed sliding clamp and the sample to be tested, and gradually tighten it until the top plate supports the clamping end of the sample;

[0021] Step 6: Use a toothed wrench to further tighten the sample through the outer gear ring of the spindle fastening plate;

[0022] 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 load, so as to loosen the spindle fastening plate.

[0023] Step 8: Start clamping the lower clamping end of the sample to be tested. First, place the top table on the main shaft of the fatigue testing machine base.

[0024] Step 9: Combine the two sliding clamps and place them on the top platform, so that the sliding guide grooves of the sliding clamps match the additional guide rails of the top platform, and check and confirm the gap between the guide grooves and the guide rails;

[0025] Step 10: Pre-install the spindle fastening plate into the spindle thread and screw it in about 5mm;

[0026] Step 11: Use a simple pick to separate the two halves of the sliding clamp and attach the inclined surfaces of the sliding clamp respectively;

[0027] Step 12: Zero the sensor of the fatigue testing machine and switch the crossbeam movement mode to manual mode;

[0028] Step 13: Depending on the position of the fatigue testing machine beam, slowly lower the fatigue testing machine beam so that the tested sample slowly enters the middle of the two separated sliding clamps;

[0029] Step 14: When the lower clamping end of the sample under test approaches the top table, slowly move the crossbeam of the fatigue testing machine while observing the reading of the force sensor. When the clamping end of the sample contacts the top table, stop moving, observe the reading of the force sensor, and continue to move the crossbeam using manual fine-tuning. Stop when the clamping pressure is less than half of the material's yield strength.

[0030] 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.

[0031] Step 16: Tighten the main shaft fastening plate of the fatigue testing machine base so that the inner bevel of the main shaft fastening plate fits tightly with the outer bevel 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;

[0032] 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 beam;

[0033] Step 18: Use the manual fine-tuning method of the fatigue testing machine beam to unload the tightening force to about 0N;

[0034] Step 19: The movement mode of the fatigue testing machine crossbeam (11) is adjusted to the software control mode.

[0035] Due to the adoption of the above technical solution, the present invention has the following beneficial effects compared with the prior art:

[0036] (1) Compared with the threaded fixture sample installation method, this fixture installation method is simple and easy to control the installation accuracy;

[0037] (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;

[0038] (3) Compared with hydraulic chucks, the cost of the clamps of this invention is low, and the tension spring structure makes the clamping tightness easy to control;

[0039] (4) Compared with the hydraulic chuck, the load applied to the sample by the clamp of this invention is in the same direction as the sample test load, and does not rely on the friction generated by the clamping force, which can effectively ensure that stable pressure and tension are provided throughout the experiment;

[0040] (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 and can also be used to clamp specimens in high and low temperature environments.

[0041] Additional aspects and advantages of the invention will become apparent from the description which follows, or may be learned by practice of the invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the description of the embodiments with reference to the following drawings, in which:

[0043] Figure 1 This is a schematic diagram of the exploded structure of the sample holder device;

[0044] Figure 2 This is a schematic diagram of the force applied to the sample clamping state of the card-type sample fixture;

[0045] 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;

[0046] Figure 4 This is a partial enlarged view of the parts position before clamping of the card-type sample fixture;

[0047] Figure 5 This is a schematic diagram of a single-sided card sample fixture clamping a sample;

[0048] Figure 6 This is a schematic diagram of a double-sided card sample fixture clamping a sample;

[0049] Figure 7 This is a partial enlarged view of the double-sided card sample fixture clamping the sample to the top position, hiding the upper spindle fastening plate and the right half of the sliding clamp.

[0050] in, Figures 1 to 7 The corresponding relationship between the reference numerals and components is as follows:

[0051] (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

[0052] In order to more clearly understand the above-mentioned objects, 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, in the absence of conflict, the embodiments of the present application and the features therein can be combined with each other.

[0053] 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 scope of protection of the present invention is not limited to the specific embodiments disclosed below.

[0054] The following combination Figures 1 to 7The top clamp type sample fixture device for fatigue performance testing of metal specimens according to an embodiment of the present invention and the method of using the same are described in detail.

[0055] The present invention proposes a top clamp type sample fixture device for fatigue performance testing of metal specimens, 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 crossbeam 11. The fatigue testing machine base 8 and the left and right ends of the fatigue testing machine crossbeam 11 are movably connected by a fatigue testing machine lead screw 9 and a fatigue testing machine slide rail 10. A fatigue testing machine high-frequency generator 12 is provided at the center of the lower surface of the fatigue testing machine crossbeam 11. A card-type sample clamp device is provided on the top of the fatigue testing machine high-frequency generator 12 and the bottom of the fatigue testing machine base 8, respectively, as shown in the attached figure. Figure 1 As 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 provided 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 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 circumferential thread in the mounting cap. The upper inner diameter of the mounting cap of the main shaft fastening disk 4 has a bevel 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 a bevel. When the main shaft fastening disk 4 is loosened, the two halves of the sliding clamp 3 can be opened to facilitate sample loading. When the main shaft fastening disk 4 is tightened, the sliding clamp 3 has a bevel combined with the main shaft fastening disk 4, and the two halves of the sliding clamp 3 are closed. When the sample is pulled down, the sample is tightened and the sample is moved downward; the lower part 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 sample to be tested, 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 the sample is fixed between the top platform 2 and the sliding clamp 3 to realize the loading of tensile and compressive stresses. The left and right sides of the additional guide rail are fixedly provided with a clamping groove 13, and the top of the main shaft 1 is fixedly provided 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 pre-tightening force to the main shaft fastening disk 4.

[0056] Under the fixed action of the card sample fixture, the force on the clamping part of the sample to be tested is as follows: Figure 3As shown in the figure, the spindle clamping plate is connected to the spindle. Rotating the spindle clamping plate causes the spindle clamping plate to move downward under the action of the threads①. The spindle clamping plate applies a lateral push to the sliding clamp through the inclined surface. When the sliding clamp closes, the spindle clamping plate applies pressure to the sliding clamp②. The arc surface of the sliding clamp presses against the arc segment of the test specimen, applying downward pressure to the fatigue specimen③. A top platform placed on the spindle provides support for the clamping end of the test specimen④. The specimen is fixed between the spindle and the sliding clamp.

[0057] A gap is maintained between the sliding clamp 3 and the vertical surface of the sample 5 to be tested, and the arc portion is the fixed end to ensure the transmission of force; the depth of the clamping end of the sliding clamp 3 should be less than the length of the parallel clamping 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 on the top platform. The depth of the top platform 2 embedded in the main shaft 1 should be reasonable to prevent the additional guide rail of the top platform from pressing on the end face of the main shaft; for ease of installation, the top platform 2 used for the upper spindle is magnetized.

[0058] A method for using a top-clamping sample fixture for fatigue performance testing of metal specimens specifically includes the following steps: For vertically clamped equipment, the fixture described in this technical solution is most suitable for first clamping the upper half. In conjunction with a fatigue testing machine, the fixture described in this technical solution is operated as follows during the fatigue test process:

[0059] Step 1: First, clamp the clamping end of the test sample and adsorb the magnetic top platform 2 onto the main shaft 1 of the fatigue testing machine beam 11. Make sure that the slot 13 of the additional guide rail of the top platform 2 is stuck to the limit block 14 on the main shaft. Make sure that the top platform has sufficient adsorption force and will not fall. Also check to make sure that the clearance above and below the additional guide rail of the top platform is appropriate.

[0060] Step 2: Place the sample 5 between the two halves of the sliding clamp 3, pinch the two halves of the sliding clamp 3, and make the sample vertical. The sample should fall freely under the action of gravity and combine with the sliding clamp 3 at the transition arc position of the sample. If this cannot be achieved, it means that the sample size exceeds the tolerance and should be processed in time.

[0061] 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;

[0062] Step 4: Pinch the two sliding clamps 3 that hold the sample to be tested, with the sample facing downward and the sliding clamps 3 facing upward. Place the two sliding clamps 3 and the sample together into the spindle fastening disk 4. 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 maintains 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 from the sliding clamp 3 platform so that the top platform 2 can support it.

[0063] Step 5: With the main shaft fastening plate 4 facing upwards, screw it onto the upper main shaft thread together with the placed sliding clamp 3 and the sample to be tested, and gradually tighten it until the top platform 2 supports the clamping end of the sample;

[0064] Step 6: Use a toothed wrench to further tighten the sample through the outer gear ring of the spindle fastening plate 4;

[0065] 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 main shaft fastening plate 4, so that the main shaft fastening plate 4 generates a tightening force in the same direction as the wrench load, so that the main shaft fastening plate 4 is loosened;

[0066] Step 8: Start clamping the lower clamping end of the sample to be tested. First, place the top platform 2 on the main shaft 1 of the fatigue testing machine base 8. Pay attention to the fit of the limiter. The clearance requirements are the same as those for the upper top platform.

[0067] Step 9: Combine the two sliding clamps 3 and place them on the top platform 2, so that the sliding guide grooves of the sliding clamps 3 match the additional guide rails of the top platform 2, and check and confirm the gap between the guide grooves and the guide rails;

[0068] Step 10: Pre-install the spindle fastening plate 4 into the spindle thread and screw it in about 5mm;

[0069] 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;

[0070] 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;

[0071] Step 13: Depending on the position of the fatigue testing machine beam 11, slowly lower the fatigue testing machine beam 11 or raise the lower beam of the testing machine to allow the tested sample to slowly enter the middle of the two separated sliding clamps 3. Pay attention to the mechanical sensor during the movement of the beam to prevent the sample from hitting the top table.

[0072] Step 14: When the lower clamping end of the sample under test approaches the top platform 2, slowly move the fatigue testing machine beam 11 while observing the force sensor reading. When the sample clamping end contacts the top platform, stop moving, observe the force sensor reading, and continue moving the beam using manual fine adjustment. When the force sensor reading is around 100N, stop. 100N is a generally recommended value. Set different tightening forces according to the strength of the sample under test, but ensure that the tightening pressure is less than half of the material's yield strength.

[0073] Step 15: Move the two halves of the sliding clamp 3 to close the sliding clamp 3 and fit it tightly against the clamping end of the sample being tested.

[0074] Step 16: Tighten the spindle fastening plate 4 of the fatigue testing machine base 8 so that the inner bevel of the spindle fastening plate 4 fits tightly with the outer bevel 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;

[0075] 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.

[0076] Step 18: Use the manual fine-tuning method of the fatigue testing machine beam 11 to unload the tightening force to about 0N;

[0077] Step 19: Adjust the movement mode of the fatigue testing machine beam 11 to software control mode.

[0078] At this point, the clamping of fatigue specimens for tensile and compressive fatigue tests using the fixture described in this invention is complete. For tensile fatigue testing or zero-tension fatigue testing, the top table can be omitted. To ensure effective clamping, the dimensions of the specimen clamping components must be designed to match the dimensions of the fixture described in this invention, ensuring the correct clearance between components and achieving proper tensile and compressive loading.

[0079] At this point, you can proceed to setting the fatigue test parameters. This part of the operation is independent of the type or scheme of the fixture. It includes setting the maximum and minimum loads according to the sample cross-sectional area and preloaded stress; setting the fatigue loading frequency as needed; setting the preload speed before the sample starts fatigue; setting the end condition of fatigue to fracture or rated life end; if it is a stage fatigue test, you also need to set the fatigue loading spectrum; after the settings are completed, start the fatigue testing machine to start the fatigue test.

[0080] At this point, the clamping of fatigue specimens for tensile and compressive fatigue tests using the fixture described in this invention is complete. For tensile fatigue testing or zero-tension fatigue testing, the top table can be omitted. To ensure effective clamping, the dimensions of the specimen clamping components must be designed to match the dimensions of the fixture described in this invention, ensuring the correct clearance between components and achieving proper tensile and compressive loading.

[0081] At this point, you can proceed to setting the fatigue test parameters. This part of the operation is independent of the type or scheme of the fixture. It includes setting the maximum and minimum loads according to the sample cross-sectional area and preloaded stress; setting the fatigue loading frequency as needed; setting the preload speed before the sample starts fatigue; setting the end condition of fatigue to fracture or rated life end; if it is a stage fatigue test, you also need to set the fatigue loading spectrum; after the settings are completed, start the fatigue testing machine to start the fatigue test.

[0082] In the description of the present invention, the term "plurality" refers to two or more than two. Unless otherwise expressly defined, the orientations or positional relationships indicated by the terms "upper" and "lower" are based on the orientations or positional relationships shown in the accompanying drawings. They are intended only to facilitate the description of the present invention and simplify the description. They do not indicate or imply that the devices or components referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, they should not be understood as limitations on the present invention. The terms "connect," "install," and "fix" should be understood in a broad sense. For example, "connection" can mean a fixed connection, a detachable connection, or an integral connection; it can be a direct connection or an indirect connection through an intermediate medium. For those skilled in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0083] Throughout this specification, terms such as "one embodiment," "some embodiments," and "specific embodiments" mean that the specific features, structures, materials, or characteristics described in conjunction with that embodiment or example are included in at least one embodiment or example of the present invention. In this specification, schematic representations of these terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

[0084] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Those skilled in the art will readily appreciate that various modifications and variations of the present invention are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention shall be included within the scope of protection of the present invention.

Claims

1. A method for using a top-clip sample fixture device for fatigue performance testing of a metal sample, wherein the metal sample fatigue performance testing device comprises a fatigue testing machine body and a top-clip sample fixture device, wherein the fatigue testing machine body comprises a fatigue testing machine base (8) and a fatigue testing machine crossbeam (11), wherein the fatigue testing machine base (8) and the fatigue testing machine crossbeam (11) are movably connected at their left and right ends through a fatigue testing machine lead screw (9) and a fatigue testing machine slide rail (10), and a fatigue testing machine high-frequency generator (12) is provided at the center position of the lower surface of the fatigue testing machine crossbeam (11), wherein the method comprises: The bottom of the fatigue testing machine high-frequency generator (12) and the top of the fatigue testing machine base (8) are respectively provided with a top clamping sample clamp device, the top clamping sample clamp device comprising 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 outer gear ring is provided 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 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 upper inner diameter of the main shaft fastening disk (4) has an inclined surface and gradually decreases, the sliding clamp (3) It is a two-half structure, 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, which is located in the sliding guide groove of the sliding clamp (3), and the left and right sides of the additional guide rail are fixedly installed with a card slot (13), and the top of the main shaft (1) is fixedly installed with a limit block (14) matching the card slot (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 disk (4); the top platform (2) is magnetized; The specific steps include: Step 1: First, clamp the upper 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 beam (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, and let the sample to be tested 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 below the fastening plate; Step 4: pinch the two halves of the sliding clamp (3) that clamp the sample to be tested, with the sample to be tested facing downward and the sliding clamp (3) facing upward. Place the two halves of the sliding clamp (3) and the sample together into the spindle fastening disk (4). The outer bevel of the sliding clamp (3) fits with the inner bevel of the spindle fastening disk (4) and slides down 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 disk (4). 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 from the sliding clamp (3). Step 5: Screw the spindle fastening plate (4) with the large opening facing upwards, 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 main shaft fastening plate (4), so that the main shaft fastening plate (4) generates a tightening force in the same direction as the wrench loading, thereby preventing the main shaft fastening plate (4) from loosening; Step 8: Start clamping the lower clamping end of the sample to be tested by first placing the top table (2) on the main shaft (1) of the fatigue testing machine base (8); Step 9: Combine the two halves of the sliding clamp (3) and place them on the top platform (2), so that the sliding guide groove of the sliding clamp (3) matches 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 5mm; Step 11: Use a simple pick to separate the two halves of the sliding clamp (3), and make the inclined surfaces of the sliding clamp (3) stick to the main shaft fastening disc respectively; Step 12: Zero the sensor of the fatigue testing machine and switch the crossbeam movement mode to manual mode; Step 13: Depending on the position of the fatigue testing machine beam (11), the fatigue testing machine beam (11) is slowly lowered so that the sample to be tested 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 fatigue testing machine beam (11) while observing the mechanical sensor reading. When the sample clamping end contacts the top platform, stop moving, observe the mechanical sensor reading, and continue to move the beam using manual fine-tuning. Stop when the clamping 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 fit it tightly against 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 bevel of the spindle fastening plate (4) fits tightly with the outer bevel 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 that of the anti-loosening spring (6) of the main shaft fastening plate (4) of the fatigue testing machine beam (11); Step 18: Use the manual fine-tuning method of the fatigue testing machine beam (11) to unload the tightening force to 0N; Step 19: The movement mode of the fatigue testing machine crossbeam (11) is adjusted to the software control mode.

2. The method for using the top clamp type sample fixture for fatigue performance testing of metal specimens according to claim 1 is 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. The method for using the top clamp type sample fixture for fatigue performance testing of metal specimens according to claim 1 is 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).

Images