An assembled three-point bending test fixture with improved test accuracy

Abstract

The application relates to the technical field of metal material performance testing, in particular to an assembled three-point bending test clamp capable of improving testing precision, which comprises a transition clamping block, a left loading table, a right loading table, a sample clamping gripper and a testing pressure head; the left loading table and the right loading table are embeddedly connected with the two transition clamping blocks, and the end portions of the transition clamping blocks away from the left loading table and the right loading table are used for being connected with a universal testing machine; the middle portion of the left loading table is provided with a to-be-tested sample containing hole used for placing a to-be-tested sample in the thickness direction of the left loading table; the sample clamping gripper is arranged on the side of the to-be-tested sample containing hole away from the right loading table; the side of the sample clamping gripper away from the right loading table is provided with a first fixing bolt; the side of the to-be-tested sample containing hole close to the right loading table is provided with a first through hole allowing the testing pressure head to move; the side of the right loading table close to the left loading table is provided with a second through hole allowing the testing pressure head to move; and the side of the second through hole away from the left loading table is provided with a second fixing bolt.

Description

Technical Field

[0001] This invention relates to the field of metal material performance testing technology, and in particular to an assembled three-point bend test fixture that can improve testing accuracy. Background Technology

[0002] The three-point bend test is used to evaluate the bending resistance of materials. During the test, the test specimen is placed on two support points, and then a displacement opposite to the support points is applied in the middle of the specimen by the test indenter to produce a three-point bend in the test specimen.

[0003] A common testing approach involves using a universal testing machine with a custom-designed three-point bend fixture. The quality of the fixture design directly impacts the accuracy and ease of testing. Existing three-point bend fixtures are mostly based on placing the sample in an open space, which requires adjusting the clamping position to prevent slippage, and sample replacement is also relatively cumbersome. Furthermore, for materials with poor bending resistance or small test specimens, the working displacement of the universal testing machine is limited, easily amplifying relative errors and reducing the accuracy of displacement testing. Summary of the Invention

[0004] To address the aforementioned problems, the present invention aims to provide an assembled three-point bend test fixture that improves testing accuracy. This assembled three-point bend test fixture, assembled using a wedge block structure, converts the vertical tensile displacement of the universal testing machine into a lateral compressive displacement. Furthermore, the wedge block inclination angle establishes a scaling relationship between the actual loaded displacement and the working displacement of the testing machine, thereby improving testing accuracy.

[0005] The objective of this invention can be achieved through the following technical solutions:

[0006] This invention provides an assembled three-point bend test fixture that can improve testing accuracy. When in use, it is connected to an external universal testing machine and includes a transition clamping block, a left loading stage, a right loading stage, a sample clamping gripper, and a test indenter.

[0007] The left and right loading stages are fitted and connected to two symmetrically spaced transition clamping blocks. The ends of the transition clamping blocks away from the left and right loading stages are used to connect to the universal testing machine.

[0008] The left loading stage has a test sample receiving hole along its thickness in the middle for placing the test sample. The sample clamping gripper is located on the side of the test sample receiving hole away from the right loading stage for fixing the test sample. A first fixing bolt for fixing the sample clamping gripper is located on the side of the sample clamping gripper away from the right loading stage. A first through hole for allowing the test indenter to move is located on the side of the test sample receiving hole near the right loading stage. A second through hole for allowing the test indenter to move is located on the side of the right loading stage near the left loading stage. A second fixing bolt for adjusting the position of the test indenter is located on the side of the second through hole away from the left loading stage.

[0009] In one embodiment of the present invention, the transition clamping block is symmetrically arranged along its thickness direction and width direction, and a loading stage groove is provided at the end of its width direction away from the universal testing machine. The loading stage groove is an inverted isosceles trapezoidal groove.

[0010] In one embodiment of the present invention, the left loading stage is symmetrically arranged along its length and thickness directions, and includes an integrated left loading stage fitting section and a left loading stage test section; the left loading stage fitting section is disposed at both ends of the left loading stage test section;

[0011] The left loading platform fitting section includes a first fitting section that is parallel and spaced apart along its thickness direction. The first fitting section is in the shape of a right trapezoid, and the inclined outer wall of the first fitting section fits against the inclined inner wall of the loading platform groove.

[0012] The left loading stage test section is a four-sided column with a test sample receiving hole extending through its thickness at its center. The left loading stage test section also has a gripper groove on the side away from the right loading stage, which allows the sample clamping gripper to move. The gripper groove is connected to the test sample receiving hole. The left loading stage test section also has a first through hole on the side away from the gripper groove, which allows the test head to move. The first through hole is connected to the test sample receiving hole.

[0013] In one embodiment of the present invention, the gripper groove is disposed at both ends along the length of the test sample receiving hole and is perpendicular to the test sample receiving hole.

[0014] In one embodiment of the present invention, the sample clamping gripper includes a gripping means and a support section. Two sets of gripping means are arranged in parallel, located at the two ends of the support section respectively, and perpendicular to the support section.

[0015] In one embodiment of the present invention, the support segment is "+" shaped, and a first hole is provided at the center of the support segment to allow the first fixing bolt to pass through; the gripping means is fitted with the gripper groove.

[0016] In one embodiment of the present invention, the left loading stage test section is provided with a first guide hole along the position of the center axis of the first hole, which allows the first fixing bolt to fix the sample and tighten the gripper.

[0017] In one embodiment of the present invention, the first through hole is perpendicular to the test sample receiving through hole, and the first through hole is located at the center of the thickness and height directions of the test section of the left loading stage (that is, the position where the first through hole connects with the test sample receiving hole is the center of the length direction of the test sample receiving hole).

[0018] In one embodiment of the present invention, the right loading platform is symmetrically arranged along its length and thickness directions, and includes a right loading platform fitting section and a right loading platform test section.

[0019] The right loading platform fitting section includes a second fitting section arranged parallel to its thickness direction. The second fitting section is in the shape of a right trapezoid, and the outer wall of the inclined surface of the second fitting section is in contact with the inner wall of the inclined surface of the loading platform groove on the side away from the first fitting section. The right loading platform test section is a four-sided column, and a protrusion is provided on the side away from the left loading platform test section. A second through hole that allows the test head to move and a second guide hole that allows the second fixing bolt to move are provided along the vertical central axis of the right loading platform test section. The second through hole and the second guide hole are connected.

[0020] In one embodiment of the present invention, the inner diameter of the second guide hole is larger than the inner diameter of the second through hole.

[0021] Compared with the prior art, the present invention has the following beneficial effects:

[0022] This invention provides an assembled three-point bend test fixture that improves testing accuracy. It can be directly applied to a universal testing machine, transferring vertical tensile displacement to lateral compressive displacement via the fixture. The inclination angles of the clamping end (transition clamping block) and the action end (left and right loading platforms) amplify the displacement from the indenter to the measuring end, increasing the measurable range and testing accuracy. Due to the structural symmetry, the pressure value can be converted by multiplying the sensor tension value by a coefficient related to the wedge inclination angle through force balance, achieving improved testing accuracy without the need for additional measuring equipment. The left and right loading platforms, the test indenter, and the sample clamping gripper are all movable components located between the transition clamping blocks, facilitating installation. This assembled three-point bend test fixture is suitable not only for testing rectangular cross-section samples but also for testing circular cross-section samples, meeting the testing needs of various samples. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of an assembled three-point bend test fixture that can improve testing accuracy.

[0024] Figure 2 This is a front view of an assembled three-point bend test fixture that can improve testing accuracy.

[0025] Figure 3 This is a schematic diagram of the transition clamping block.

[0026] Figure 4 A cross-sectional view of the transition clamping block;

[0027] Figure 5 This is a schematic diagram of the left loading stage;

[0028] Figure 6 This is a sectional view (vertical) of the left loading stage;

[0029] Figure 7 This is a cross-sectional view (horizontal) of the left loading stage;

[0030] Figure 8 This is a schematic diagram of the right loading stage.

[0031] Figure 9 This is a sectional view (vertical) of the right loading stage;

[0032] Figure 10 This is a cross-sectional view (horizontal) of the right loading stage;

[0033] Figure 11 A schematic diagram of the structure for clamping the sample;

[0034] Figure 12 This is a schematic diagram of the structure of the first fixing bolt;

[0035] Figure 13 This is a schematic diagram of the second fixing bolt;

[0036] Figure 14 This is a schematic diagram of the test indenter structure;

[0037] Figure 15 This is a schematic diagram of the structure of the test piece;

[0038] The diagram is labeled as follows: 1. Transition clamping block; 2. Left loading stage; 3. Right loading stage; 4. Sample clamping gripper; 5. First fixing bolt; 6. Second fixing bolt; 7. Test indenter; 8. Sample to be tested; 11. Loading stage groove; 12. Reinforcing plate; 21. Left loading stage fitting section; 22. Left loading stage test section; 31. Right loading stage fitting section; 32. Right loading stage test section; 33. Protrusion block; 41. Support section; 42. Gripper; 43. First hole; 211. First fitting section; 221. Sample to be tested receiving hole; 222. Gripper groove; 223. First through hole; 224. First guide hole; 311. Second fitting section; 321. Second through hole; 322. Second guide hole. Detailed Implementation

[0039] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments.

[0040] In the description of this invention, unless otherwise explicitly specified and limited, the terms "connected," "linked," and "fixed" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0041] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0042] In the description of this embodiment, the terms "upper," "lower," "left," and "right," etc., refer to the orientation or positional relationship shown in the accompanying drawings. They are used only for ease of description and simplification of operation, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the present invention. In addition, the terms "first" and "second" are used only for distinction in description and have no special meaning.

[0043] In this invention, the connection direction of the two transition clamping blocks is taken as the length direction ( Figure 1 (in the z-direction), with the connection direction of the first fixing bolt and the second fixing bolt as the width direction ( Figure 1 (in the x-direction), with the connection direction of the two gripping hands of the sample clamping grip as the thickness direction ( Figure 1 middle y direction).

[0044] Example 1

[0045] This embodiment provides an assembled three-point bend test fixture that can improve testing accuracy. In use, it is connected to an external universal testing machine, such as... Figures 1-15As shown, the system includes a transition clamping block 1, a left loading stage 2, a right loading stage 3, a sample clamping gripper 4, and a test indenter 7. The left loading stage 2 and the right loading stage 3 are fitted and connected to two symmetrically spaced transition clamping blocks 1. The ends of the transition clamping blocks 1 away from the left loading stage 2 and the right loading stage 3 are used to connect to the universal testing machine. The middle part of the left loading stage 2 has a sample receiving hole 221 along its thickness direction for placing the sample to be tested 8. The sample clamping gripper 4 is located in the sample receiving hole 221 away from the right loading stage 3. On one side, it is used to fix the test sample 8; the sample clamping gripper 4 is provided with a first fixing bolt 5 for fixing the sample clamping gripper 4 on the side away from the right loading platform 3; the test sample receiving hole 221 is provided with a first through hole 223 that allows the test pressure head 7 to move on the side near the right loading platform 3; the right loading platform 3 is provided with a second through hole 321 that allows the test pressure head 7 to move on the side near the left loading platform 2, and a second fixing bolt 6 for adjusting the position of the test pressure head 7 is provided on the side of the second through hole 321 away from the left loading platform 2.

[0046] Furthermore, the transition clamping block 1 is symmetrically arranged along its thickness and width directions, and a loading platform groove 11 is provided at the end of its width direction away from the universal testing machine (the middle part of the two loading platform grooves 11 is a reinforcing plate 12, which is used to join and limit the left loading platform 2 and the right loading platform 3). The loading platform groove 11 is an inverted isosceles trapezoidal groove.

[0047] Furthermore, the left loading stage 2 is symmetrically arranged along its length and thickness directions, including an integrated left loading stage fitting section 21 and a left loading stage test section 22; the left loading stage fitting section 21 is located at both ends of the left loading stage test section 22; the left loading stage fitting section 21 includes a first fitting section 211 arranged parallel to each other along its thickness direction, the first fitting section 211 being in the shape of a right trapezoid, and the inclined outer wall of the first fitting section 211 fitting against the inclined inner wall of the loading stage groove 11; the left loading stage test section 211... The test section 22 is a four-sided column with a test sample receiving hole 221 that runs through its thickness direction at its center. The left loading stage test section 22 is also provided with a gripper groove 222 that allows the sample clamping gripper 4 to move on the side away from the right loading stage 3. The gripper groove 222 is connected to the test sample receiving hole 221. The left loading stage test section 22 is provided with a first through hole 223 that allows the test pressure head 7 to move on the side away from the gripper groove 222. The first through hole 223 is connected to the test sample receiving hole 221.

[0048] Furthermore, the gripper groove 222 is provided at both ends of the test sample receiving hole 221 along its length and is perpendicular to the test sample receiving hole 221.

[0049] Furthermore, the sample clamping gripper 4 includes a gripping means 42 and a support section 41. Two sets of gripping means 42 are arranged in parallel, located at the two ends of the support section 41 respectively, and perpendicular to the support section 41. The support section 41 is "+" shaped, and a first hole 43 is provided at the center of the support section 41 to allow the first fixing bolt 5 to pass through. The gripping means 42 is fitted into the gripper groove 222. The left loading stage test section 22 is provided with a first guide hole 224 along the axis of the first hole 43 to allow the first fixing bolt 5 to fix the sample clamping gripper 4.

[0050] Furthermore, the first through hole 223 is perpendicular to the through hole that accommodates the test sample 8, and the first through hole 223 is located at the center of the thickness and height directions of the left loading stage test section 22 (that is, the position where the first through hole 223 connects to the test sample accommodating hole 221 is the center of the length direction of the test sample accommodating hole 221). One end of the first through hole 223 is located at the end of the left loading stage test section 22 near the right loading stage 3, and the other end is located on the side of the test sample accommodating hole 221 away from the right loading stage 3.

[0051] Furthermore, the right loading platform 3 is symmetrically arranged along its length and thickness directions, including a right loading platform fitting section 31 and a right loading platform test section 32; the right loading platform fitting section 31 includes a second fitting section 311 arranged parallel to its thickness direction, the second fitting section 311 is in the shape of a right trapezoid, and the inclined outer wall of the second fitting section 311 is in contact with the inclined inner wall of the loading platform groove 11 on the side away from the first fitting section 211; the right loading platform test section 32 is a four-sided column, and a protrusion 33 is provided on the side away from the left loading platform test section 22. Along the vertical central axis of the right loading platform test section 32, a second through hole 321 that allows the test head 7 to move is provided, and a second guide hole 322 that allows the second fixing bolt 6 to move is provided; the second through hole 321 is connected to the second guide hole 322; the inner diameter of the second guide hole 322 is larger than the inner diameter of the second through hole 321.

[0052] Among them, the first guide hole 224, the first hole 43, the first through hole 223, the second through hole 321, the second guide hole 322, the first fixing bolt 5, and the second fixing bolt 6 are all on the same central axis along the width direction.

[0053] Example 2

[0054] This embodiment provides a method for using an assembled three-point bend test fixture that can improve testing accuracy, including the following steps:

[0055] First, the transition clamping block 1 is fitted and connected to the left loading stage 2 and the right loading stage 3, and the transition clamping block 1 is connected to the universal testing machine; the test sample 8 is placed in the test sample receiving hole 221, the gripper 42 gradually approaches the test sample 8 through the gripper groove 222, and the first fixing bolt 5 is used to fix the sample clamping gripper 4 to the test section 22 of the left loading stage, so as to achieve support and fixation of the test sample 8; the test head 7 is placed in the second through hole 321, and the second fixing bolt 6 is used to fix the test head 7 to the test sample 8.

[0056] When the universal testing machine clamps the transition clamping block 1 and moves and loads it in the vertical direction, the left loading platform 2 and the right loading platform 3 approach each other in the horizontal direction through the linkage between the components. The test head 7 moves together with the right loading platform 3 through the second fixing bolt 6 and applies pressure load to the test sample 8. The test head 7 and the sample clamping gripper 4 contact the three points of the test sample 8 respectively, thus realizing the three-point bend scenario.

[0057] The above description of the embodiments is provided to enable those skilled in the art to understand and use the invention. It will be apparent to those skilled in the art that various modifications can be made to these embodiments, and the general principles described herein can be applied to other embodiments without inventive effort. Therefore, the present invention is not limited to the above embodiments, and any improvements and modifications made by those skilled in the art based on the interpretation of the present invention, without departing from the scope of the invention, should be within the protection scope of the present invention.

Claims

1. An assembled three-point bend test fixture that improves testing accuracy, which is connected to an external universal testing machine during use, characterized in that: It includes a transition clamping block (1), a left loading stage (2), a right loading stage (3), a sample clamping gripper (4), and a test indenter (7); The left loading stage (2) and the right loading stage (3) are fitted and connected to two symmetrically spaced transition clamping blocks (1). The ends of the transition clamping blocks (1) away from the left loading stage (2) and the right loading stage (3) are used to connect to the universal testing machine. The left loading platform (2) has a test sample receiving hole (221) for placing the test sample (8) in the middle along its thickness direction. The test sample clamping gripper (4) is located on the side of the test sample receiving hole (221) away from the right loading platform (3) for fixing the test sample (8). The side of the test sample clamping gripper (4) away from the right loading platform (3) is provided with a first fixing bolt (5) for fixing the test sample clamping gripper (4). The side of the test sample receiving hole (221) near the right loading platform (3) is provided with a first through hole (223) that allows the test pressure head (7) to move. The side of the right loading platform (3) near the left loading platform (2) is provided with a second through hole (321) that allows the test pressure head (7) to move. The side of the second through hole (321) away from the left loading platform (2) is provided with a second fixing bolt (6) for adjusting the position of the test pressure head (7). The transition clamping block (1) is provided with a loading platform groove (11) in the shape of an inverted isosceles trapezoid. The left loading platform (2) and the right loading platform (3) are respectively provided with a first fitting section (211) and a second fitting section (311) in the shape of a right trapezoid, with the outer wall of the inclined surface fitting against the inner wall of the inclined surface of the loading platform groove (11). When the transition clamping block (1) moves vertically, it can transfer its vertical tensile displacement to the lateral compressive displacement of the left loading platform (2) and the right loading platform (3), and thus generate the three-point bending of the sample to be tested.

2. The assembled three-point bend test fixture according to claim 1, characterized in that, The transition clamping block (1) is symmetrically arranged along its thickness and width directions, and a loading stage groove (11) is provided at the end of its width direction away from the universal testing machine.

3. The assembled three-point bend test fixture according to claim 2, characterized in that, The left loading platform (2) is symmetrically arranged along its length and thickness directions, including an integrated left loading platform fitting section (21) and a left loading platform test section (22); the left loading platform fitting section (21) is located at both ends of the left loading platform test section (22); The left loading stage test section (22) is a four-sided column with a test sample receiving hole (221) that runs through its thickness direction at its center. The left loading stage test section (22) away from the right loading stage (3) is also provided with a gripper groove (222) that allows the sample clamping gripper (4) to move. The gripper groove (222) is connected to the test sample receiving hole (221). The left loading stage test section (22) away from the gripper groove (222) is provided with a first through hole (223) that allows the test pressure head (7) to move. The first through hole (223) is connected to the test sample receiving hole (221).

4. The assembled three-point bend test fixture according to claim 3, characterized in that, The gripper groove (222) is located at both ends of the test sample receiving hole (221) along its length and is perpendicular to the test sample receiving hole (221).

5. The assembled three-point bend test fixture according to claim 4, characterized in that, The sample clamping gripper (4) includes a gripping means (42) and a support section (41). Two sets of gripping means (42) are arranged in parallel, located at the two ends of the support section (41) and perpendicular to the support section (41).

6. The assembled three-point bend test fixture according to claim 5, characterized in that, The support section (41) has a first hole (43) at its center, which allows the first fixing bolt (5) to pass through; the gripping means (42) is fitted into the gripper groove (222).

7. The assembled three-point bend test fixture according to claim 6, characterized in that, The left loading stage test section (22) is provided with a first guide hole (224) along the position of the center axis of the first hole (43) to allow the first fixing bolt (5) to fix the sample clamping gripper (4).

8. The assembled three-point bend test fixture according to claim 7, characterized in that, The first through hole (223) is perpendicular to the through hole of the test sample (8), and the first through hole (223) is located at the center of the thickness and height of the test section (22) of the left loading stage.

9. The assembled three-point bend test fixture according to claim 8, characterized in that, The right loading platform (3) is symmetrically arranged along its length and thickness directions, including a right loading platform fitting section (31) and a right loading platform test section (32). The right loading platform test section (32) is a four-sided column. A protrusion (33) is provided on the side away from the left loading platform test section (22). Along the vertical central axis of the right loading platform test section (32), a second through hole (321) is provided to allow the test head (7) to move, and a second guide hole (322) is provided to allow the second fixing bolt (6) to move. The second through hole (321) and the second guide hole (322) are connected.

10. The assembled three-point bend test fixture according to claim 9, characterized in that, The inner diameter of the second guide hole (322) is larger than the inner diameter of the second through hole (321).

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