Clamping device suitable for tension-tension fatigue performance test of linear material

Abstract

The utility model belongs to the field of fatigue strength test of metal materials, and particularly relates to a clamping device suitable for tension-tension fatigue performance test of linear materials, which is characterized in that a fatigue machine connecting sheet is fixed on a fatigue machine, and the load is reset; the long-rod bolt, the springs and the sample upper clamp are assembled, so that the resultant force of the pre-pressure of the two springs is the amplitude of the fatigue load, and the pre-pressure of the springs is reserved; fixing two ends of the linear material by using a winding clamp, and loading to an average value of a fatigue load; mounting the assembled long-rod bolt, spring and sample upper clamp on the sample, and connecting with a fatigue machine connecting sheet; loading to the maximum value of the fatigue load; a sample lower clamp is hung on the sample; the distance between the linear material and the fatigue machine stand column is measured, a tensioner and a U-shaped bolt baffle assembly are installed, and it is ensured that the distance between the linear material and the fatigue machine stand column is not changed; and unloading until the wire rod is bent, clearing the load, and then starting a fatigue test. According to the utility model, effective tension-tension fatigue test can be carried out on the linear material, and accurate wire fatigue performance data can be obtained.

Description

Technical Field

[0001] The utility model belongs to the field of fatigue strength testing of metal materials, in particular to a clamping device suitable for testing the tensile fatigue performance of linear materials. Background Art

[0002] In the field of material science research and engineering applications, fatigue performance testing of linear materials (such as metal wire, plastic wire, glass fiber, etc.) is crucial. Fatigue performance testing can reflect the performance changes of materials under cyclic loads, providing an important basis for material selection, design, optimization and service life prediction. However, traditional fatigue performance testing methods for linear materials have many shortcomings, such as unstable clamping, low test accuracy, and complex operation, which limit the accuracy and reliability of the test results.

[0003] There are already some clamping devices on the market for testing the tensile fatigue performance of linear materials, but these clamping devices are either for linear materials with thicker diameters (more than 1mm), or most of them have the disadvantage of unreasonable design leading to failure of the linear materials at the connection, which makes it difficult to meet the effective and accurate testing needs; there are no clamping devices and testing methods for testing the tensile fatigue performance of linear materials with a diameter of less than 300 microns. At present, the fatigue performance test of linear materials with a diameter of less than 300 microns generally adopts a rotating bending type clamping device and testing method; under this testing method, the bending stress borne by the linear material is often inconsistent with the tensile fatigue load actually borne by the linear material, and the fatigue performance of the material under different load forms is often inconsistent, and cannot be directly compared.

[0004] Therefore, developing a clamping device for testing the tensile fatigue performance of linear materials with simple structure, convenient operation, stable clamping and high test accuracy is of great significance for improving the accuracy and reliability of fatigue performance testing of linear materials. At the same time, the promotion and application of this device will help promote the development of material science research and engineering applications, and provide strong support for innovation in related fields. Utility Model Content

[0005] The purpose of the utility model is to provide a clamping device suitable for the pull-pull fatigue performance test of linear materials, so as to solve the above-mentioned problems existing in the prior art and meet the accuracy, high precision and high efficiency requirements of the fatigue performance test of linear materials.

[0006] The purpose of this utility model is achieved through the following technical solutions:

[0007] The utility model comprises a long rod bolt, a spring, an upper sample clamp, a lower sample clamp, a fatigue machine connecting plate, a tensioner and a U-bolt baffle assembly, wherein the left and right sides of the upper sample clamp, the lower sample clamp and the fatigue machine connecting plate are respectively connected by long rod bolts, and are respectively tightened and positioned by nuts, and the sample to be tested is clamped by the upper sample clamp and the lower sample clamp; a spring is sleeved on the long rod bolt between the upper sample clamp and the nut end of the long rod bolt, and the two ends of the spring are respectively abutted against the upper sample clamp and the nut end of the long rod bolt, and the resultant force of the spring pre-pressure on the long rod bolts on the left and right sides is the amplitude of the fatigue load; the fatigue machine connecting plate is fixedly connected to the fatigue machine, and fatigue machine columns are provided on the left and right sides of the clamping device, and the fatigue machine columns on each side are connected to the sample to be tested through the U-bolt baffle assembly and the tensioner.

[0008] Wherein: a center hole A is opened on the sample upper fixture, and long rod bolt through holes A are symmetrically opened on the left and right sides of the center hole A. After the long rod bolt passes through the long rod bolt through hole A, it is tightened and positioned by a nut; a gap is opened on the sample upper fixture for installation of linear materials after tensioning, and the gap is connected to the center hole A.

[0009] The nut for tightening and positioning the upper sample clamp is nut A, and two nuts A are threadedly connected to the long rod bolt on each side. The two nuts A on each side are located between the upper sample clamp and the lower sample clamp, and abut against the upper sample clamp.

[0010] A center hole B is provided on the sample lower clamp, and U-shaped openings are symmetrically provided on the left and right sides of the center hole B. The U-shaped opening is clamped on the long rod bolt, and the nut for tightening and positioning the sample lower clamp is the nut B. Two nuts B are threadedly connected to the long rod bolt on each side, and the two nuts B on each side are respectively located on the upper and lower sides of the sample lower clamp, and are respectively abutted against the sample lower clamp, and the sample lower clamp is tightened and positioned by the upper and lower nuts B; a gap for installing the linear material after tensioning is provided on the sample lower clamp, and the gap is connected to the center hole B.

[0011] Long rod bolt through holes B are respectively provided on the left and right sides of the fatigue machine connecting plate, and the nut for tightening and positioning the fatigue machine connecting plate is a nut C. Two nuts C are threadedly connected to the long rod bolt on each side, and the two nuts C on each side are respectively located on the upper and lower sides of the fatigue machine connecting plate and respectively abut against the fatigue machine connecting plate. After the long rod bolt on each side passes through the long rod bolt through hole B on the same side, it is tightened and positioned by the upper and lower nuts C.

[0012] The upper sample clamp, the lower sample clamp and the fatigue machine connecting piece are respectively provided with process through holes for reducing the overall weight of the clamping device.

[0013] A distance of 20 times the diameter of the linear material is left between the lower fixture of the sample and the connecting piece of the fatigue machine.

[0014] The U-bolt baffle assembly includes a U-bolt, a baffle and a nut D. The U-bolt is clamped on the fatigue machine column. Both sides of the open end of the U-bolt are passed through by baffles and tightened by nuts D respectively, so that the baffle abuts against the fatigue machine column.

[0015] The advantages and positive effects of the utility model are:

[0016] 1. The utility model can stably clamp the linear material, has a simple structure, or adopts cheap and readily available industrial standard products, or adopts simple-shaped plates processed by wire cutting, and has low cost.

[0017] 2. The utility model is easy to operate and has good robustness; even if the experiment stops unexpectedly, the clamping state of the sample is not affected and the test can be directly restarted, thus ensuring the test efficiency.

[0018] 3. The utility model can ensure that the load distribution of the sample during the fatigue test is stable, and the maximum force position of the sample appears at the non-contact position of the sample, ensuring the accuracy and effectiveness of the test results. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a schematic diagram of the overall structure of the utility model;

[0020] Figure 2 for Figure 1 The structural front view of the fixture on the sample;

[0021] Figure 3 for Figure 1 The structural front view of the lower fixture of the middle sample;

[0022] Figure 4 for Figure 1 The structural front view of the connecting piece of the middle fatigue machine;

[0023] Figure 5 It is a structural schematic diagram of the utility model and the fatigue machine column;

[0024] Figure 6 This is a diagram of the fatigue test process of the utility model;

[0025] Figure 7 This is a diagram of fatigue test results of the utility model;

[0026] Among them: 1 is a long-rod bolt, 2 is a spring, 3 is a sample upper fixture, 4 is a nut A, 5 is a sample lower fixture, 6 is a fatigue machine connecting plate, 7 is a tensioner, 8 is a U-shaped bolt, 9 is a gap, 10 is a linear material, 11 is a casting mold, 12 is a fatigue machine column, 13 is a U-shaped opening, 14 is a nut B, 15 is a nut C, 16 is a baffle, 17 is a nut D, 18 is a long-rod bolt through hole A, 19 is a center hole A, 20 is a center hole B, 21 is a long-rod bolt through hole B, and 22 is a process through hole. DETAILED DESCRIPTION

[0027] The utility model is further described in detail below in conjunction with the accompanying drawings.

[0028] like Figures 1 to 5 As shown, the utility model comprises a long rod bolt 1, a spring 2, an upper sample clamp 3, a lower sample clamp 5, a fatigue machine connecting piece 6, a tensioner 7 and a U-bolt baffle assembly, wherein the left and right sides of the upper sample clamp 3, the lower sample clamp 5 and the fatigue machine connecting piece 6 are respectively connected by the long rod bolt 1, and are respectively tightened and positioned by nuts, and the sample to be tested is clamped by the upper sample clamp 3 and the lower sample clamp 5; a spring 2 is sleeved on the long rod bolt 1 between the upper sample clamp 3 and the nut end of the long rod bolt 1, and the two ends of the spring 2 are respectively abutted against the upper sample clamp 3 and the nut end of the long rod bolt 1, and the resultant force of the pre-pressure of the spring 2 on the long rod bolts 1 on the left and right sides is the amplitude of the fatigue load, ensuring that the force on the upper sample clamp 3 and the lower sample clamp 5 is the amplitude of the fatigue load; the fatigue machine connecting piece 6 is fixedly connected to the fatigue machine, and fatigue machine columns 12 are provided on the left and right sides of the clamping device, and the fatigue machine columns 12 on each side are connected to the sample to be tested through the U-bolt baffle assembly and the tensioner 7.

[0029] The elastic coefficient of the spring 2 in this embodiment is less than 5 N / mm, which is convenient for maintaining the preload of the spring 2 during the fatigue test; the smaller the spring elastic coefficient, the smaller the change in the preload.

[0030] The sample upper fixture 3 of this embodiment is provided with a center hole A19, and long-rod bolt through holes A18 are symmetrically provided on the left and right sides of the center hole A19. After the long-rod bolt 1 passes through the long-rod bolt through hole A18, it is tightened and positioned by a nut. The sample upper fixture 3 is provided with a slit 9 for installing the linear material 10 after tensioning, and the slit 9 is connected to the center hole A19. In this embodiment, the nut for tightening and positioning the sample upper fixture 3 is a nut A4, and two nuts A4 are threadedly connected to the long-rod bolt 1 on each side, and the two nuts A4 on each side are located between the sample upper fixture 3 and the sample lower fixture 5, and abut against the lower surface of the sample upper fixture 3.

[0031] The sample lower fixture 5 of this embodiment is provided with a center hole B20, and U-shaped openings 13 are symmetrically provided on the left and right sides of the center hole B20. The design of the U-shaped opening 13 is convenient for installation on the long rod bolt 1, and the U-shaped opening 13 is clamped on the long rod bolt 1; the nut for tightening and positioning the sample lower fixture 5 of this embodiment is a nut B14, and two nuts B14 are threadedly connected on each side of the long rod bolt 1, and the two nuts B14 on each side are respectively located on the upper and lower sides of the sample lower fixture 5, and respectively abut against the upper and lower surfaces of the sample lower fixture 5, and the sample lower fixture 5 is tightened and positioned by the upper and lower nuts B14. The sample lower fixture 5 is provided with a slit 9 for installation of the linear material 10 after tensioning, and the slit 9 is connected to the center hole B20.

[0032] In this embodiment, long rod bolt through holes B21 are respectively opened on the left and right sides of the fatigue machine connecting plate 6, and the nut for tightening and positioning the fatigue machine connecting plate 6 is a nut C15. Two nuts C15 are threadedly connected to the long rod bolt 1 on each side. The two nuts C15 on each side are respectively located on the upper and lower sides of the fatigue machine connecting plate 6, and are respectively abutted against the upper and lower surfaces of the fatigue machine connecting plate 6. After the long rod bolt 1 on each side passes through the long rod bolt through hole B21 on the same side, it is tightened and positioned by the upper and lower nuts C15.

[0033] The upper sample fixture 3, the lower sample fixture 5 and the fatigue machine connecting piece 6 of this embodiment are all fixed by double nuts to prevent the nuts from loosening during the fatigue process.

[0034] In this embodiment, the upper sample clamp 3, the lower sample clamp 5 and the fatigue machine connecting piece 6 are respectively provided with process through holes 22, which reduces the overall weight of the clamping device.

[0035] In this embodiment, a distance of 20 times the diameter of the linear material 10 is left between the sample lower fixture 5 and the fatigue machine connecting piece 6, so as to solve the problem of poor centering during the sample installation process.

[0036] The U-bolt baffle assembly of this embodiment includes a U-bolt 8, a baffle 16 and a nut D17. The U-bolt 8 is clamped on the fatigue machine column 12. The baffles 16 pass through both sides of the open end of the U-bolt 8 and are tightened by nuts D17 respectively, so that the baffles 16 abut against the fatigue machine column 12. Both sides of the clamping device are fixed to the fatigue machine column 12 by the tensioner 7 and the U-bolt baffle assembly, and the clamping device is fixed horizontally as a whole to prevent lateral vibration during the fatigue process. The tensioner 7 of this embodiment is a prior art and will not be described in detail here.

[0037] The testing method of the utility model comprises the following steps:

[0038] Step A, fixing the fatigue machine connecting piece 6 to the fatigue machine;

[0039] Step B, assemble the long-rod bolt 1, the spring 2 and the sample upper fixture 3, so that the combined force of the preload of the two springs 2 on the left and right sides is the amplitude of the fatigue load, and limit the sample upper fixture 3 by two nuts A4 so that the preload of the spring 2 is retained;

[0040] Step C, fixing both ends of the linear material 10 with a winding fixture (the winding fixture of this embodiment is a prior art), and loading to an average value of fatigue load;

[0041] Step D, mount the assembled long rod bolt 1, spring 2 and sample upper fixture 3 on the sample to be tested, connect them to the fatigue machine connecting piece 6, and fix them with two nuts C15;

[0042] Step E, loading to the maximum value of fatigue load;

[0043] Step F, mount the sample lower fixture 5 on the sample and fix it by two nuts B14, and the casting mold 11 outside the linear material 10 is located between the sample upper fixture 3 and the sample lower fixture 5;

[0044] Step G, measuring the distance between the linear material 10 and the fatigue machine column 12, installing the tensioner 7 and the U-bolt baffle assembly, and ensuring that the distance between the linear material 10 and the fatigue machine column 12 does not change;

[0045] Step H, unloading until the linear material 10 bends, clearing the load, and then starting the fatigue test.

[0046] Experimental example

[0047] The utility model is further explained by taking the ultra-high strength steel cord monofilament as an example. The ultra-high strength steel cord refers to ST225 with a strength of 3000-3500 MPa.

[0048] In this experimental example, a 150mm long M5 screw rod is used as the long rod bolt 1, a spring 2 with an elastic coefficient of 5N / mm is used, the sample upper fixture 3 is made of 5mm thick aluminum alloy, the sample lower fixture 5 is made of 3mm thick aluminum alloy, and the fatigue machine connecting piece 6 is made of 2.5mm thick aluminum alloy. In the horizontal fixing device: the adjustable length range of the tensioner 7 is the shortest 120mm and the longest 200mm, and the diameter of the U-bolt 8 is M6.

[0049] In the experimental example, the maximum fatigue load of the ultra-high strength steel cord monofilament is between 70N and 85N, and the stress ratio of the fatigue load is 0.1. Therefore, the combined preload force of the two springs 2 is between 31.5N and 38.3N. Each time the fatigue load is adjusted, the preload of the spring 2 needs to be adjusted accordingly.

[0050] Fix the fatigue machine connecting piece 6 to the fatigue machine; assemble the long rod bolt 1, spring 2, sample upper clamp 3 and nut A4 so that the resultant force of the pre-stress of the two springs 2 is the amplitude of the fatigue load, and the pre-stress of the spring 2 is retained by limiting with the double nut A4; fix the two ends of the linear material 10 with a winding clamp and load to the average value of the fatigue load; mount the assembled long rod bolt 1, spring 2, sample upper clamp 3 and nut A4 on the sample, and connect them to the fatigue machine connecting piece 6, and fix them with the double nut C15; load to the maximum value of the fatigue load; mount the sample lower clamp 5 on the sample and fix it with the double nut B14; measure the distance between the linear material 10 and the fatigue machine column 12, install the tensioner 7 and the U-bolt baffle assembly, and ensure that the distance between the linear material 10 and the fatigue machine column 12 does not change; unload until the wire is slightly bent, clear the load, and then start the fatigue test.

[0051] The stability of the fatigue test process is mainly reflected in the stability of the load cycle and the stability of the sample. Stable cyclic load is a necessary condition to ensure the accuracy of the test results. The stability of the sample is reflected in the fact that its strain response under cyclic load remains stable, which can be characterized by displacement. The load and displacement during the loading process are as follows: Figure 6 As shown, it can be seen that the load and displacement can remain stable.

[0052] The relationship between stress and life obtained from fatigue testing is as follows: Figure 7 As shown, it can be used to evaluate the fatigue strength of the material. In this experimental example, the fatigue strength of the material is about 1990MPa.

[0053] The above description is only an implementation method of the utility model and is not intended to limit the protection scope of the utility model. Any modification, equivalent replacement, improvement, expansion, etc. made within the spirit and principle of the utility model are included in the protection scope of the utility model.

Claims

1. A clamping device suitable for tensile fatigue performance testing of linear materials, characterized in that: The invention comprises a long-rod bolt (1), a spring (2), an upper sample clamp (3), a lower sample clamp (5), a fatigue machine connecting plate (6), a tensioner (7) and a U-bolt baffle assembly, wherein the left and right sides of the upper sample clamp (3), the lower sample clamp (5) and the fatigue machine connecting plate (6) are respectively connected by the long-rod bolt (1) and are respectively tightened and positioned by nuts, and the sample to be tested is clamped by the upper sample clamp (3) and the lower sample clamp (5); the upper sample clamp (3) and the nut end of the long-rod bolt (1) are connected to each other. A spring (2) is sleeved on the long rod bolt (1) between the two ends of the spring (2), the two ends of which are respectively in contact with the clamp (3) on the sample and the nut end of the long rod bolt (1), and the resultant force of the pre-pressure of the spring (2) on the long rod bolt (1) on the left and right sides is the amplitude of the fatigue load; the fatigue machine connecting piece (6) is fixedly connected to the fatigue machine, and the left and right sides of the clamping device are provided with fatigue machine columns (12), and the fatigue machine columns (12) on each side are connected to the sample to be tested through a U-bolt baffle assembly and a tensioner (7).

2. The clamping device for tensile fatigue performance testing of linear materials according to claim 1, characterized in that: The sample upper fixture (3) is provided with a center hole A (19), and long rod bolt through holes A (18) are symmetrically provided on the left and right sides of the center hole A (19). After the long rod bolt (1) passes through the long rod bolt through hole A (18), it is tightened and positioned by a nut; the sample upper fixture (3) is provided with a gap (9) for installing the linear material (10) after tensioning, and the gap (9) is connected to the center hole A (19).

3. The clamping device for tensile fatigue performance testing of linear materials according to claim 1, characterized in that: The nut that tightens and positions the sample upper clamp (3) is a nut A (4), and two nuts A (4) are threadedly connected to the long rod bolt (1) on each side. The two nuts A (4) on each side are located between the sample upper clamp (3) and the sample lower clamp (5), and are in contact with the sample upper clamp (3).

4. The clamping device for tensile fatigue performance testing of linear materials according to claim 1, characterized in that: The sample lower fixture (5) is provided with a center hole B (20), and U-shaped openings (13) are symmetrically provided on the left and right sides of the center hole B (20). The U-shaped opening (13) is clamped on the long rod bolt (1), and the nut for tightening and positioning the sample lower fixture (5) is a nut B (14). Two nuts B (14) are threadedly connected to the long rod bolt (1) on each side. The two nuts B (14) on each side are respectively located on the upper and lower sides of the sample lower fixture (5) and are respectively abutted against the sample lower fixture (5). The sample lower fixture (5) is tightened and positioned by the upper and lower nuts B (14); the sample lower fixture (5) is provided with a gap (9) for installing the linear material (10) after tensioning, and the gap (9) is connected to the center hole B (20).

5. The clamping device for tensile-tensile fatigue performance testing of linear materials according to claim 1, characterized in that: The left and right sides of the fatigue machine connecting plate (6) are respectively provided with long rod bolt through holes B (21), and the nuts for tightening and positioning the fatigue machine connecting plate (6) are nuts C (15). Two nuts C (15) are threadedly connected to the long rod bolt (1) on each side, and the two nuts C (15) on each side are respectively located on the upper and lower sides of the fatigue machine connecting plate (6) and respectively abut against the fatigue machine connecting plate (6). After the long rod bolt (1) on each side passes through the long rod bolt through hole B (21) on the same side, it is tightened and positioned by the upper and lower nuts C (15).

6. The clamping device for tensile-tensile fatigue performance testing of linear materials according to claim 1, characterized in that: The upper sample clamp (3), the lower sample clamp (5) and the fatigue machine connecting piece (6) are respectively provided with process through holes (22) for reducing the overall weight of the clamping device.

7. The clamping device for tensile-tensile fatigue performance testing of linear materials according to claim 1, characterized in that: A distance of 20 times the diameter of the linear material (10) is left between the sample lower fixture (5) and the fatigue machine connecting piece (6).

8. The clamping device for tensile-tensile fatigue performance testing of linear materials according to claim 1, characterized in that: The U-shaped bolt baffle assembly comprises a U-shaped bolt (8), a baffle (16) and a nut D (17). The U-shaped bolt (8) is clamped on the fatigue machine column (12). Both sides of the open end of the U-shaped bolt (8) are passed through the baffle (16) and are tightened by the nut D (17) respectively, so that the baffle (16) is in contact with the fatigue machine column (12).

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