Bending test device and method

Abstract

The invention discloses a bending test device and method, and belongs to the technical field of copper-clad steel material tests.The bending test device comprises a hydraulic drive assembly and a set of multiple test clamps and fixing clamps, the specifications of the multiple test clamps and fixing clamps are matched with the radius of a test sample, and the hydraulic drive assembly is connected with the hydraulic drive assembly. Using a test clamp and a fixing clamp with corresponding specifications based on the radius of the test sample; the rear sides of the hydraulic driving assemblies are connected with the corresponding fixing clamps, the top output ends of the hydraulic driving assemblies are connected with the corresponding test clamps, the test clamps and the fixing clamps form clamping gaps for clamping test samples, the test samples are arranged in all the clamping gaps, and the test clamps are controlled by the hydraulic driving assemblies to move vertically. And the extrusion directions of the middle part and the two sides of the test sample are opposite through the test clamp and the fixing clamp, so that the bending or straightening of the test sample is realized. The bending and straightening integrated device meets bending and straightening integrated operation, and the structure and operation are simplified.

Description

Technical Field

[0001] The present invention belongs to the technical field of bending tests, and in particular relates to a bending test device and method. Background Art

[0002] In daily applications, most materials need to withstand bending forces, tensile forces, and compressive forces, so the materials need to be tested for their bending, tensile, and compressive properties. However, existing bending tests mostly use manual tools for bending and straightening. The operation process is greatly affected by human factors, making it difficult to ensure the accuracy and repeatability of the test data. Some automated testing equipment has a single function. The existing engineering site automated testing equipment on the market can usually only complete a single bending or straightening function, and cannot achieve integrated bending and straightening operations, which increases the complexity of the test and the cost of the equipment. Bending can easily cause permanent deformation of the sample, affecting the accuracy of the mechanical performance data. In addition, conventional bending equipment often has a sample radius mismatch and cannot be placed inside the equipment for testing, resulting in low test efficiency. The bending and straightening objects of existing equipment are mostly construction steel bars, which are complex in design and bulky in size, making it difficult to meet the needs of on-site testing and limiting the use scenarios. Summary of the Invention

[0003] To address the deficiencies in the prior art, the present invention provides a bending test device and method that can meet the needs of laboratory and field testing of copper-clad steel materials through precise bending and straightening.

[0004] The present invention adopts the following technical solutions.

[0005] The first aspect of the present invention discloses a bending test device, which is characterized by comprising: a hydraulic drive assembly, a test fixture and a fixing fixture,

[0006] The specifications of the test fixture and fixing fixture are used to match the radius of the test specimen;

[0007] The fixing portion of the hydraulic drive assembly is connected to the corresponding fixing fixture, the power output end of the hydraulic drive assembly is connected to the test fixture, and the opening of the fixing fixture faces the test fixture, so that a clamping gap for clamping the test sample is formed between the test fixture and the fixing fixture;

[0008] The test sample is set in all clamping gaps. When the hydraulic drive assembly drives the test fixture to move vertically, the pressure exerted by the test fixture on the middle of the test sample is in the opposite direction to the pressure exerted by the fixed fixture on both sides of the test sample, so as to bend or straighten the test sample.

[0009] Preferably, the fixing fixture includes: a V-shaped block, a bending fixing column and a straightening fixing column, the opening of the V-shaped block faces the test fixture, the lower end of the V-shaped block and the fixing part of the hydraulic drive assembly are detachably connected, the straightening fixing columns are symmetrically arranged in the middle position of the two arms of the V-shaped block, and the bending fixing columns are symmetrically arranged at the top position, and the height difference between the bending fixing column and the straightening fixing column forms a first clamping gap for clamping the test sample.

[0010] Preferably, the test fixture includes: a connecting block, a straightening pressure block and a bending top block, the bottom of the bending top block and the power output end of the hydraulic drive assembly are detachably connected, a connecting block is provided on the upper rear side of the bending top block, the upper end of the connecting block is connected to the straightening pressure block, and the height difference between the straightening pressure block and the bending top block forms a second clamping gap for clamping the test sample.

[0011] Preferably, the test sample is arranged in the first clamping gap and the second clamping gap. When the hydraulic drive assembly drives the test sample to move upward through the test fixture, the bending top block squeezes the middle of the test sample upward until the bending fixing column applies a downward squeezing force to both sides of the test sample, causing the test sample to bend; when the hydraulic drive assembly drives the bent test sample to move downward through the test fixture, the straightening fixing column squeezes both sides of the test sample upward until the straightening pressure block applies a downward squeezing force to the middle of the test sample.

[0012] Preferably, the upper end of the bent top block is an arc structure.

[0013] Preferably, the radius of the arc structure is three to three and a half times the radius of the test sample.

[0014] Preferably, there are multiple test fixtures and fixed fixtures, the height differences of the first clamping gaps of the multiple fixed fixtures are different, and the height differences of the second clamping gaps of the multiple test fixtures are also different. By replacing the fixed fixture and the test fixture, the height differences of the first clamping gap and the second clamping gap are adjusted respectively, so that the height differences of all clamping gaps are higher than twice the radius of the test sample, and test samples of different radii can pass through all clamping gaps.

[0015] Preferably, the arc structure radius of the upper end of the bent top block of multiple test fixtures is different, and the test fixture is replaced based on the radius of the test sample to adjust the arc structure radius so that the test sample only bears bending stress.

[0016] Preferably, the hydraulic drive assembly includes: a hydraulic cylinder and a hydraulic cylinder seat, a hydraulic cylinder is arranged inside the hydraulic cylinder seat, the rear side of the hydraulic cylinder seat is detachably connected to the fixed fixture, a hydraulic rod is arranged on the upper side of the hydraulic cylinder, the upper end of the hydraulic rod is detachably connected to the test fixture, and the hydraulic cylinder drives the test fixture to move up and down through the hydraulic rod, driving the test sample to move synchronously.

[0017] A second aspect of the present invention discloses a bending test method, based on the aforementioned bending test device, comprising the following steps:

[0018] Place the test sample in the clamping gap between the corresponding test fixture and the fixed fixture;

[0019] The test fixture is driven upward by the hydraulic drive assembly to squeeze the two sides of the test sample downward and the middle upward, so that the test sample is bent to measure the bending performance;

[0020] The test fixture is driven downward and restored to its original position by the hydraulic drive assembly, so that the two sides of the bent test sample are squeezed upward and the middle part is squeezed downward to straighten the test sample;

[0021] The test sample is bent repeatedly at the same position multiple times to obtain bending performance data.

[0022] Preferably, the step of placing the test sample in the clamping gap between the corresponding test fixture and the fixing fixture comprises the following steps:

[0023] Adjust the height difference of the clamping gap by replacing the corresponding fixing fixture and test fixture respectively, so that the height difference of all clamping gaps is higher than twice the radius of the test sample;

[0024] At the same time, the arc structure radius on the test fixture is adjusted by replacing the corresponding test fixture so that the arc structure radius is three to three and a half times the radius of the test sample.

[0025] Preferably, the method of driving the test fixture upward by a hydraulic drive assembly to squeeze the two sides of the test sample downward and the middle portion upward, so that the test sample is bent to measure the bending performance, comprises the following steps:

[0026] The test fixture drives the test sample upward, and the bent top block presses the middle of the test sample upward;

[0027] Until both sides of the test sample are squeezed downward by the bending fixed column;

[0028] As the test sample continues to move upward, the test sample is bent and deformed until the test fixture moves to the highest point to measure the bending performance of the test sample.

[0029] Preferably, the method of driving the test fixture downward to restore the original position by a hydraulic drive assembly, so that the two sides of the bent test sample are squeezed upward and the middle part is squeezed downward, so that the test sample is straightened and restored, includes the following steps:

[0030] The test fixture drives the bent test sample to move downward to restore it to its original position, and the fixed column is straightened to squeeze the two sides of the bent test sample upward;

[0031] Until the middle of the bending test sample is squeezed downward by the straightening block;

[0032] As the test fixture continues to move downward until it returns to its original position, the test sample returns to a straight rod state and there is no obvious permanent deformation of the test sample.

[0033] Compared with the prior art, the present invention has the following advantages:

[0034] The present invention drives the test fixture up and down by driving the hydraulic rod through the hydraulic cylinder, and makes the extrusion direction of the middle and two sides of the test sample opposite through the test fixture and the fixed fixture, thereby realizing bending or straightening of the test sample, improving applicability, meeting the integrated operation of bending and straightening, simplifying the structure and operation, saving floor space and equipment cost, making the measurement data accurate, and achieving high efficiency of bending test.

[0035] The specifications of multiple test fixtures and fixed fixtures of the present invention match the radius of the test sample. On the one hand, by replacing the corresponding fixed fixture and test fixture, the height difference between the first clamping gap and the second clamping gap is adjusted respectively, so that the height difference of all clamping gaps is higher than twice the radius of the test sample, which improves the versatility and enables test samples of different radii to be set in the clamping gap for testing. On the other hand, by replacing the corresponding test fixture, the arc structure radius of the bending top block is adjusted so that the arc structure radius is three to three and a half times the radius of the test sample, ensuring that the test sample will not be subjected to excessive shear force during the bending process, avoiding permanent deformation of the test sample, enabling repeated bending tests, saving material costs, and the multiple bending points of the test sample are all in the same position, which can more accurately detect the bending performance of the test sample and avoid test errors.

[0036] The present invention simplifies the structure by detachably connecting the test fixture and the fixing fixture to the hydraulic drive assembly, making the device easy to carry and able to meet both laboratory and field testing needs. At the same time, the corresponding test fixture and fixing fixture can be replaced according to the radius of the test sample, so that the device can meet the testing of test samples of different radii and lengths, thereby improving versatility and the efficiency of bending detection, and accurately completing bending and straightening operations.

[0037] The test fixture, the fixing fixture and the hydraulic cylinder seat of the present invention are all manufactured by integrally forming with a high-strength mold, and have high strength, fatigue resistance and wear resistance, thereby improving durability. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 It is a front view of the present invention;

[0039] In the figure: 1. Test fixture; 2. Fixing fixture; 3. Hydraulic cylinder; 4. Hydraulic cylinder seat; 5. Straightening pressure block; 6. Bending top block; 7. Bending fixing column; 8. Straightening fixing column; 9. Hydraulic rod; 10. Test sample; 11. Connecting block; 12. V-shaped block. DETAILED DESCRIPTION

[0040] To make the objectives, technical solutions, and advantages of the present invention more clear, the technical solutions of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention. The embodiments described in this application are only part of the embodiments of the present invention, not all of them. Based on the spirit of the present invention, other embodiments obtained by ordinary technicians in this field without making creative efforts are all within the scope of protection of the present invention.

[0041] Example 1

[0042] like Figure 1 As shown, embodiment 1 of the present invention discloses a bending test device, which includes: a hydraulic drive assembly, a test fixture 1 and a fixed fixture 2, wherein the specifications of the test fixture 1 and the fixed fixture 2 match the radius of the test sample 10;

[0043] The fixed portion of the hydraulic drive assembly is connected to the corresponding fixed fixture 2, the power output end of the hydraulic drive assembly is connected to the test fixture 1, and the opening of the fixed fixture faces the test fixture, so that a clamping gap for clamping the test sample 10 is formed between the test fixture 1 and the fixed fixture 2;

[0044] The test sample 10 is set in all clamping gaps. When the hydraulic drive assembly drives the test fixture 1 to move vertically, the pressure exerted by the test fixture 1 on the middle of the test sample 10 is in the opposite direction to the pressure exerted by the fixed fixture 2 on both sides of the test sample 10, so that the test sample 10 is bent or straightened.

[0045] The fixing fixture 2 includes: a V-shaped block 12, a bending fixing column 7 and a straightening fixing column 8. The opening of the V-shaped block 12 faces the test fixture 1. The lower end of the V-shaped block 12 is detachably connected to the fixing part of the hydraulic drive assembly. The straightening fixing columns 8 are symmetrically arranged in the middle position of the two arms of the V-shaped block 12, and the bending fixing columns 7 are symmetrically arranged at the top position. The height difference between the bending fixing columns 7 and the straightening fixing columns 8 forms a first clamping gap for clamping the test sample 10.

[0046] The test fixture 1 includes: a connecting block 11, a straightening pressure block 5 and a bending top block 6. The bottom of the bending top block 6 is detachably connected to the power output end of the hydraulic drive assembly. A connecting block 11 is provided on the upper rear side of the bending top block 6. The upper end of the connecting block 11 is connected to the straightening pressure block 5. The height difference between the straightening pressure block 5 and the bending top block 6 forms a second clamping gap for clamping the test sample 10.

[0047] In a specific embodiment, the test sample 10 is set in the first clamping gap and the second clamping gap. When the hydraulic drive assembly drives the test sample 10 to move upward through the test fixture 1, the bending top block 6 squeezes the middle of the test sample 10 upward until both sides of the test sample 10 are squeezed downward by the bending fixing column 7, so that the test sample 10 is bent. When the test sample 10 bent by the hydraulic drive assembly through the test fixture 1 moves downward to return to its original position, the straightening fixing column 8 squeezes both sides of the test sample 10 upward until the middle of the test sample 10 is squeezed downward by the straightening pressure block 5, so that the test sample 10 is straightened and restored.

[0048] The upper end of the bent top block (6) is an arc structure, and the radius of the arc structure is three to three and a half times the radius of the test sample (10).

[0049] Example 2

[0050] There are multiple test fixtures 1 and fixed fixtures 2, and the height differences of the first clamping gaps of the multiple fixed fixtures 2 are different, and the height differences of the second clamping gaps of the multiple test fixtures 1 are also different. By replacing the fixed fixture 2 and the test fixture 1, the height differences of the first clamping gap and the second clamping gap are adjusted respectively, so that the height differences of all clamping gaps are higher than twice the radius of the test sample 10, and the test samples 10 with different radii can pass through all clamping gaps.

[0051] The arc structure radius of the upper end of the bending top block 6 of multiple test fixtures 1 is different. The test fixture 1 is replaced based on the radius of the test sample 10 to adjust the arc structure radius, so that the arc structure radius is three to three and a half times the radius of the test sample 10. Then, the test sample 10 only bears bending stress, so that the test sample 10 has no obvious permanent deformation when undergoing the bending test, ensuring that the test sample 10 will not be subjected to excessive shear force during the bending process, causing permanent deformation of the test sample 10.

[0052] The hydraulic drive assembly includes: a hydraulic cylinder 3 and a hydraulic cylinder seat 4. The hydraulic cylinder 3 is arranged inside the hydraulic cylinder seat 4. The rear side of the hydraulic cylinder seat 4 is detachably connected to the fixed fixture 2. A hydraulic rod 9 is arranged on the upper side of the hydraulic cylinder 3. The upper end of the hydraulic rod 9 is detachably connected to the test fixture 1. The hydraulic cylinder 3 drives the hydraulic rod 9 to drive the test fixture 1 up and down, thereby driving the test sample 10 to move synchronously.

[0053] In another specific embodiment, based on the radius of the test sample 10, the height difference between the first clamping gap and the second clamping gap is adjusted by replacing the corresponding fixing fixture 2 and the test fixture 1, so that the height difference of all clamping gaps is higher than twice the radius of the test sample 10, so that test samples 10 of different radii can be placed in all clamping gaps. At the same time, the arc structure radius of the bent top block 6 is adjusted by replacing the corresponding test fixture 1, so that the arc structure radius is three to three and a half times the radius of the test sample 10;

[0054] Then the corresponding test fixture 1 and the hydraulic rod 9 are detachably connected, the corresponding fixed fixture 2 and the rear side of the hydraulic cylinder seat 4 are detachably connected, the test sample 10 is set in the clamping gap, and the hydraulic cylinder 3 drives the test fixture 1 to move vertically through the hydraulic rod 9, thereby bending or straightening the test sample 10.

[0055] Preferably, the device adopts a modular design, the test fixture 1 and the hydraulic rod 9 are connected by bolts, and the fixing fixture 2 is slot-engaged with the hydraulic cylinder seat 4.

[0056] The lower side of the straightening pressure block 5 and the upper side of the bending top block 6 of the test fixture 1 are both provided with a concave structure that is recessed toward the rear. The test sample 10 abuts against the concave structure to prevent the test sample 10 from sliding and falling out during the test, making the test sample 10 move more smoothly.

[0057] The straightening pressing block 5 is in the shape of an elongated strip, which ensures that the test sample 10 can return to a straight state without being twisted during the straightening process.

[0058] Preferably, the test fixture 1, the fixing fixture 2 and the hydraulic cylinder seat 4 are all manufactured by integrally forming with a high-strength mold, and have high strength, fatigue resistance and wear resistance, thereby improving durability.

[0059] The working principle of the present invention is as follows: in the initial state, the hydraulic rod 9 is not extended or retracted, the test fixture 1 is at the lowest end, the first clamping gap and the second clamping gap are at the same height, so that the test sample 10 is conveniently set in the clamping gap; in the working state, the hydraulic cylinder 3 drives the hydraulic rod 9 to drive the test fixture 1 to move upward, the test fixture 1 drives the test sample 10 to move upward, and the bending top block 6 squeezes the middle of the test sample 10 upward; until both sides of the test sample 10 are subjected to the downward squeezing force of the bending fixing column 7; as the test sample 10 continues to move upward, the test sample 10 is bent and deformed, until the test fixture 1 moves to the highest point to measure the bending performance of the test sample 10. Hydraulic cylinder 3 then drives hydraulic rod 9 to return test fixture 1 to its original position. Test fixture 1 then moves bent test specimen 10 downward, returning it to its original position. Straightening column 8 presses upward on both sides of bent test specimen 10 until the center of bent test specimen 10 is subjected to the downward pressure of straightening block 5. As test fixture 1 continues to move downward until it returns to its original position, test specimen 10 returns to its straight state, exhibiting no noticeable permanent deformation. Repeat the bending test multiple times at the same location to obtain accurate bending performance data.

[0060] Example 3

[0061] Embodiment 3 of the present invention discloses a bending test method, comprising the following steps:

[0062] Step 1: Place the test sample 10 in the clamping gap between the corresponding test fixture 1 and the fixed fixture 2;

[0063] Step 1.1: Adjust the height difference between the first clamping gap and the second clamping gap by replacing the corresponding fixing fixture 2 and the test fixture 1, respectively, so that the height difference of all clamping gaps is greater than twice the radius of the test sample 10;

[0064] Step 1.2: At the same time, the arc structure radius is adjusted by replacing the corresponding test fixture 1 so that the arc structure radius is three to three and a half times the radius of the test sample 10;

[0065] Step 2: The test fixture 1 is driven upward by the hydraulic drive assembly to squeeze the test sample 10 downward on both sides and upward in the middle, so that the test sample 10 is bent to measure the bending performance;

[0066] Step 2.1: The test fixture 1 moves the test sample 10 upward, and the bent top block 6 presses the middle of the test sample 10 upward;

[0067] Step 2.2: until both sides of the test sample 10 are subjected to downward squeezing force from the bent fixing columns 7;

[0068] Step 2.3: As the test sample 10 continues to move upward, the test sample 10 is bent and deformed until the test fixture 1 moves to the highest point to measure the bending performance of the test sample 10.

[0069] Step 3: The test fixture 1 is driven downward to return to its original position by the hydraulic drive assembly, so that the two sides of the bent test sample 10 are squeezed upward and the middle is squeezed downward, so that the test sample 10 is straightened and restored;

[0070] Step 3.1: The test fixture 1 moves the bent test sample 10 downward to restore it to its original position, and the fixing column 8 is straightened to press upward on both sides of the bent test sample 10;

[0071] Step 3.2: until the middle of the bending test sample 10 is subjected to the downward squeezing force of the straightening pressing block 5;

[0072] Step 3.3: As the test fixture 1 continues to move downward until it returns to its original position, the test sample 10 returns to a straight rod state, and the test sample 10 has no obvious permanent deformation.

[0073] Step 4: The test sample 10 is bent repeatedly at the same position multiple times to obtain accurate bending performance data.

[0074] Compared with the prior art, the present invention has the following advantages:

[0075] The present invention drives the test fixture up and down by driving the hydraulic rod through the hydraulic cylinder, and makes the extrusion direction of the middle and two sides of the test sample opposite through the test fixture and the fixed fixture, thereby realizing bending or straightening of the test sample, improving applicability, meeting the integrated operation of bending and straightening, simplifying the structure and operation, saving floor space and equipment cost, making the measurement data accurate, and achieving high efficiency of bending test.

[0076] The specifications of multiple test fixtures and fixed fixtures of the present invention match the radius of the test sample. On the one hand, by replacing the corresponding fixed fixture and test fixture, the height difference between the first clamping gap and the second clamping gap is adjusted respectively, so that the height difference of all clamping gaps is higher than twice the radius of the test sample, which improves the versatility and enables test samples of different radii to be set in the clamping gap for testing. On the other hand, by replacing the corresponding test fixture, the arc structure radius of the bending top block is adjusted so that the arc structure radius is three to three and a half times the radius of the test sample, ensuring that the test sample will not be subjected to excessive shear force during the bending process, avoiding permanent deformation of the test sample, enabling repeated bending tests, saving material costs, and the multiple bending points of the test sample are all in the same position, which can more accurately detect the bending performance of the test sample and avoid test errors.

[0077] The present invention simplifies the structure by detachably connecting the test fixture and the fixing fixture to the hydraulic drive assembly, making the device easy to carry and able to meet both laboratory and field testing needs. At the same time, the corresponding test fixture and fixing fixture can be replaced according to the radius of the test sample, so that the device can meet the testing of test samples of different radii and lengths, thereby improving versatility and the efficiency of bending detection, and accurately completing bending and straightening operations.

[0078] The test fixture, the fixing fixture and the hydraulic cylinder seat of the present invention are all manufactured by integrally forming with a high-strength mold, and have high strength, fatigue resistance and wear resistance, thereby improving durability.

[0079] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, ordinary technicians in the field should understand that the specific implementation methods of the present invention can still be modified or replaced by equivalents. Any modification or equivalent replacement that does not depart from the spirit and scope of the present invention should be covered by the scope of protection of the claims of the present invention.

Claims

1. A bending test device, characterized in that: include: Hydraulic drive assembly, test fixture (1) and fixing fixture (2), The specifications of the test fixture (1) and the fixing fixture (2) are used to match the radius of the test sample (10); The fixing portion of the hydraulic drive assembly is connected to a corresponding fixing fixture (2), the power output end of the hydraulic drive assembly is connected to the test fixture (1), and the opening of the fixing fixture faces the test fixture, so that a clamping gap for clamping the test sample (10) is formed between the test fixture (1) and the fixing fixture (2); The test sample (10) is set in all clamping gaps. When the hydraulic drive assembly drives the test fixture (1) to move vertically, the pressure exerted by the test fixture (1) on the middle of the test sample (10) is opposite to the pressure exerted by the fixed fixture (2) on both sides of the test sample (10), so that the test sample (10) is bent or straightened.

2. A bending test device according to claim 1, characterized in that: The fixing fixture (2) comprises: a V-shaped block (12), a bending fixing column (7) and a straightening fixing column (8); the opening of the V-shaped block (12) faces the test fixture (1); the lower end of the V-shaped block (12) is detachably connected to the fixing portion of the hydraulic drive assembly; the straightening fixing columns (8) are symmetrically arranged at the middle position of the two arms of the V-shaped block (12); and the bending fixing columns (7) are symmetrically arranged at the top position; the height difference between the bending fixing columns (7) and the straightening fixing columns (8) forms a first clamping gap for clamping the test sample (10).

3. A bending test device according to claim 2, characterized in that: The test fixture (1) comprises: a connecting block (11), a straightening pressure block (5) and a bending top block (6); the bottom of the bending top block (6) is detachably connected to the power output end of the hydraulic drive assembly; a connecting block (11) is provided on the upper rear side of the bending top block (6); the upper end of the connecting block (11) is connected to the straightening pressure block (5); and the height difference between the straightening pressure block (5) and the bending top block (6) forms a second clamping gap for clamping the test sample (10).

4. A bending test device according to claim 3, characterized in that: The test sample (10) is arranged in the first clamping gap and the second clamping gap. When the hydraulic drive assembly drives the test sample (10) to move upward through the test fixture (1), the bending top block (6) presses the middle of the test sample (10) upward until the bending fixing column (7) applies a downward squeezing force to both sides of the test sample (10), so that the test sample (10) is bent; when the hydraulic drive assembly drives the bent test sample (10) to move downward through the test fixture (1), the straightening fixing column (8) presses both sides of the test sample (10) upward until the straightening pressing block (5) applies a downward squeezing force to the middle of the test sample (10).

5. A bending test device according to claim 3, characterized in that: The upper end of the bent top block (6) is an arc structure.

6. A bending test device according to claim 5, characterized in that: The radius of the arc structure is three to three and a half times the radius of the test sample (10).

7. A bending test device according to claim 3, characterized in that: There are multiple test fixtures (1) and fixed fixtures (2), the height differences of the first clamping gaps of the multiple fixed fixtures (2) are different, and the height differences of the second clamping gaps of the multiple test fixtures (1) are also different. By replacing the fixed fixture (2) and the test fixture (1), the height differences of the first clamping gap and the second clamping gap are adjusted respectively, so that the height differences of all clamping gaps are higher than twice the radius of the test sample (10), and the test samples (10) of different radii can pass through all the clamping gaps.

8. A bending test device according to claim 7, characterized in that: The arc structure radius of the upper end of the bending top block (6) of the multiple test fixtures (1) is different. The test fixture (1) is replaced based on the radius of the test sample (10) to adjust the arc structure radius so that the test sample (10) only bears bending stress.

9. A bending test device according to any one of claims 1 to 8, characterized in that: The hydraulic drive assembly comprises: a hydraulic cylinder (3) and a hydraulic cylinder seat (4); the hydraulic cylinder (3) is arranged inside the hydraulic cylinder seat (4); the rear side of the hydraulic cylinder seat (4) is detachably connected to the fixing fixture (2); a hydraulic rod (9) is arranged on the upper side of the hydraulic cylinder (3); the upper end of the hydraulic rod (9) is detachably connected to the test fixture (1); the hydraulic cylinder (3) drives the test fixture (1) to move up and down through the hydraulic rod (9), thereby driving the test sample (10) to move synchronously.

10. A bending test method, based on the bending test device according to any one of claims 1 to 9, characterized in that: The test sample (10) is arranged in the clamping gap between the corresponding test fixture (1) and the fixed fixture (2); The test fixture (1) is driven upward by a hydraulic drive assembly to squeeze the two sides of the test sample (10) downward and the middle part upward, so that the test sample (10) is bent to measure the bending performance; The test fixture (1) is driven downward to return to its original position by a hydraulic drive assembly, so that the two sides of the bent test sample (10) are squeezed upward and the middle part is squeezed downward, so that the test sample (10) is straightened and restored; The test sample (10) is bent repeatedly at the same position for multiple times to obtain bending performance data.

11. A bending test method according to claim 10, characterized in that: The step of placing the test sample (10) in the clamping gap between the corresponding test fixture (1) and the fixing fixture (2) comprises the following steps: Adjusting the height difference of the clamping gaps by replacing the corresponding fixing fixture (2) and the test fixture (1) so that the height difference of all the clamping gaps is higher than twice the radius of the test sample (10); At the same time, the arc structure radius on the test fixture (1) is adjusted by replacing the corresponding test fixture (1), so that the arc structure radius is three to three and a half times the radius of the test sample (10).

12. A bending test method according to claim 10, characterized in that: The method drives the test fixture (1) upward by a hydraulic drive assembly to squeeze the test sample (10) downward on both sides and upward in the middle, so that the test sample (10) is bent to measure the bending performance, comprising the following steps: The test fixture (1) drives the test sample (10) to move upward, and the bent top block (6) presses the middle part of the test sample (10) upward; Until both sides of the test sample (10) are subjected to downward squeezing force from the bent fixing column (7); As the test sample (10) continues to move upward, the test sample (10) is bent and deformed until the test fixture (1) moves to the highest point to measure the bending performance of the test sample (10).

13. A bending test method according to claim 10, characterized in that: The method of driving the test fixture (1) downward to restore the original position by a hydraulic drive assembly, so that the two sides of the bent test sample (10) are squeezed upward and the middle part is squeezed downward, so that the test sample (10) is straightened and restored, comprises the following steps: The test fixture (1) drives the bent test sample (10) to move downward to restore to its original position, and the fixing column (8) is straightened to press the two sides of the bent test sample (10) upward; until the middle of the bending test sample (10) is subjected to the downward squeezing force of the straightening pressing block (5); As the test fixture (1) continues to move downward until it returns to its original position, the test sample (10) returns to a straight rod state, and the test sample (10) has no obvious permanent deformation.

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