Clamp for fatigue test of cross-shaped welding spot sample

Abstract

The utility model relates to a clamp for a fatigue test of a cross-shaped welding spot sample. The clamp comprises a wedge-shaped lower clamping block, a lower clamping head, a wedge-shaped upper clamping block, an upper clamping head and a sample locking mechanism, the wedge-shaped lower clamping block is connected with a wedge-shaped lower jaw of the fatigue testing machine in a matched mode, and the wedge-shaped upper clamping block is connected with a wedge-shaped upper jaw of the fatigue testing machine in a matched mode. The lower chuck is mounted at the top of the wedge-shaped lower clamping block, and the upper chuck is mounted at the bottom of the wedge-shaped upper clamping block; the cross-shaped welding spot sample is arranged between the lower chuck and the upper chuck, the cross-shaped welding spot sample is composed of a first welding base material and a second welding base material, the first welding base material is connected with the lower chuck through a sample locking mechanism, and the second welding base material is connected with the upper chuck through the sample locking mechanism. The clamp is suitable for being installed on a fatigue testing machine with a wedge-shaped jaw and carrying out a fatigue test, the cross-shaped sample does not need a pre-punching step, stress concentration of the sample due to holes is avoided, and the accuracy of a test result is improved.

Description

Technical Field

[0001] This utility model relates to the field of fatigue testing technology for resistance spot welding, and in particular to a fixture for fatigue testing of cross-shaped weld point specimens of resistance spot welding. Background Technology

[0002] Resistance spot welding, as an efficient joining method, is widely used in the manufacturing process of automotive parts and complete vehicles, greatly promoting the development of the automotive industry. However, under cyclic loading, weld joints can suddenly fracture after a period of time; this phenomenon is called "weld joint fatigue." It has been reported that 70% to 90% of welded structural failures are caused by fatigue fracture of welded joints. Therefore, research on the fatigue performance of weld joints in automotive steel is of great significance.

[0003] Chinese utility model patent CN 216309608 U discloses a "fatigue testing device for resistance spot welded cross-shaped samples," used for conducting fatigue tests on resistance spot welded samples in a cross shape. The technical solution is as follows: the upper and lower clamps are both rectangular steel blocks. The upper surface of each rectangular steel block has an upward protrusion in the middle. Bolt connection holes are located at both ends of the rectangular steel blocks. A threaded hole for a clamping rod is located in the center of the protrusion. The lower parts of the upper and lower clamping rods are connected to the threaded holes in the protrusions of the upper and lower clamps, respectively. The upper clamp is placed on the upper surface of the upper strip plate of the cross-shaped sample, and the lower clamp is placed on the lower surface of the lower strip plate of the cross-shaped sample. Bolts fix the upper and lower clamps to the cross-shaped sample. The upper ends of the upper and lower clamping rods are clamped onto the two jaws of a fatigue testing machine. This device allows fatigue testing of cross-shaped welded samples to be performed on a conventional tensile testing machine. However, both the upper and lower clamping rods of this device are cylindrical, making it only compatible with fatigue testing machines that have cylindrical clamping ends. Currently, the most widely used fatigue testing machines have wedge-shaped clamping ends. Therefore, the use of the aforementioned cross-shaped sample fatigue testing device is limited, hindering its widespread application. Furthermore, before installing the sample, the aforementioned cross-shaped sample fatigue testing device requires pre-drilled positioning holes on the cross-shaped sample. However, as is well known, fatigue testing places high demands on the sample processing technology. Cracks or rough surfaces on the sample can cause stress concentration, and fracture usually occurs at stress concentration points, directly affecting the test results. Summary of the Invention

[0004] This utility model provides a jig for fatigue testing of cross-shaped weld joint specimens, which is suitable for installation and fatigue testing on fatigue testing machines with wedge-shaped jaws. The cross-shaped weld joint specimens do not require a pre-drilling step, avoiding stress concentration caused by drilling and improving the accuracy of test results.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] A jig for fatigue testing of a cross-shaped weld joint specimen includes a wedge-shaped lower clamping block, a lower clamp, a wedge-shaped upper clamping block, an upper clamp, and a specimen locking mechanism. The wedge-shaped lower clamping block is used to engage with the wedge-shaped lower jaw of a fatigue testing machine, and the wedge-shaped upper clamping block is used to engage with the wedge-shaped upper jaw of the fatigue testing machine. The lower clamp is installed on the top of the wedge-shaped lower clamping block, and the upper clamp is installed on the bottom of the wedge-shaped upper clamping block. The cross-shaped weld joint specimen is placed between the lower clamp and the upper clamp, forming a cross-shaped structure that engages with the cross-shaped weld joint specimen. The cross-shaped weld joint specimen consists of a first welding base material and a second welding base material. The two ends of the first welding base material are detachably fixed to the corresponding ends of the lower clamp through the specimen locking mechanism, and the two ends of the second welding base material are detachably fixed to the corresponding ends of the upper clamp through the specimen locking mechanism.

[0007] The wedge-shaped lower clamping block is connected to the wedge-shaped lower jaw of the fatigue testing machine, and the wedge-shaped upper clamping block is connected to the wedge-shaped upper jaw of the fatigue testing machine, respectively, by corresponding cylindrical positioning pins.

[0008] The first and second welding base materials are strip-shaped structures of the same size, and the lower and upper clamps are block-shaped structures that match the shapes of the first and second welding base materials.

[0009] The wedge-shaped lower clamping block and the lower chuck, and the wedge-shaped upper clamping block and the upper chuck are detachably connected by connecting bolts.

[0010] The sample locking mechanism consists of a U-shaped clamp and a locking bolt; one set of U-shaped clamps is located on the outer side of the end of the welding base material one and the lower clamp, and the corresponding U-shaped clamp is fixedly connected to the lower clamp by the locking bolt; another set of U-shaped clamps is located on the outer side of the end of the welding base material two and the upper clamp, and the corresponding U-shaped clamp is fixedly connected to the upper clamp by the locking bolt.

[0011] The lower clamp has the same structure as the upper clamp, both being divided into three parts along the longitudinal direction: clamping sections at both ends and a connecting section in the middle. The connecting section has a groove on the side near the cross-shaped welding point sample, with a bolt hole in the middle of the groove to cooperate with the connecting bolt, and a washer at the connection point. The U-shaped sleeve is on the outside of the corresponding clamping section. The surfaces of the clamping section that contact the welding base material 1 and welding base material 2 are respectively provided with anti-slip structures. The side of the clamping section opposite to the anti-slip structure has a threaded hole to cooperate with the locking bolt, and a washer at the connection point.

[0012] The anti-slip structure is a serrated anti-slip surface.

[0013] Compared with the prior art, the beneficial effects of this utility model are:

[0014] The aforementioned fatigue test fixture for cross-shaped weld joint specimens is suitable for installation and fatigue testing on fatigue testing machines with wedge-shaped jaws. Cross-shaped weld joint specimens do not require a pre-drilling step, avoiding stress concentration caused by drilling, thus improving the accuracy of test results and providing reliable technical support for welding quality in automobile manufacturing. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of the structure of the fatigue test fixture for the cross-shaped weld point specimen described in this utility model.

[0016] Figure 2a This is a front view of the wedge-shaped upper clamping block (or wedge-shaped lower clamping block) described in this utility model.

[0017] Figure 2b yes Figure 2a Side view.

[0018] Figure 2c yes Figure 2a Top view.

[0019] Figure 3a This is a front view of the upper clamp (or lower clamp) described in this utility model.

[0020] Figure 3b yes Figure 3a Side view.

[0021] Figure 3c yes Figure 3a A bottom view.

[0022] Figure 4a This is the front view of the U-shaped clip described in this utility model.

[0023] Figure 4b yes Figure 4a The right view.

[0024] Figure 5 This is a top view of the cross-shaped weld joint sample.

[0025] In the diagram: 1. Wedge-shaped lower clamping block; 2. Lower chuck; 3. Wedge-shaped upper clamping block; 4. Upper chuck; 5. U-shaped clamp; 6. Connecting bolt; 7. Washer 1; 8. Locking bolt; 9. Washer 2; 10. Cylindrical locating pin; 11. Welding base material 1; 12. Welding base material 2; 13. Weld nugget. Detailed Implementation

[0026] The specific embodiments of this utility model will be further described below with reference to the accompanying drawings:

[0027] like Figure 1As shown, the present invention discloses a jig for fatigue testing of a cross-shaped weld point specimen, comprising a wedge-shaped lower clamping block 1, a lower clamp 2, a wedge-shaped upper clamping block 3, an upper clamp 4, and a specimen locking mechanism. The wedge-shaped lower clamping block 1 is used to connect with the wedge-shaped lower jaw of the fatigue testing machine, and the wedge-shaped upper clamping block 3 is used to connect with the wedge-shaped upper jaw of the fatigue testing machine. The lower clamp 2 is installed on the top of the wedge-shaped lower clamping block 1, and the upper clamp 4 is installed on the bottom of the wedge-shaped upper clamping block 3. The cross-shaped weld point specimen is placed between the lower clamp 2 and the upper clamp 4, forming a cross-shaped structure that cooperates with the cross-shaped weld point specimen. The cross-shaped weld point specimen is composed of a first welding base material 11 and a second welding base material 12, wherein the two ends of the first welding base material 11 are detachably fixedly connected to the corresponding ends of the lower clamp 2 through the specimen locking mechanism, and the two ends of the second welding base material 12 are detachably fixedly connected to the corresponding ends of the upper clamp 4 through the specimen locking mechanism.

[0028] The wedge-shaped lower clamping block 1 and the wedge-shaped lower jaw of the fatigue testing machine, and the wedge-shaped upper clamping block 3 and the wedge-shaped upper jaw of the fatigue testing machine, are respectively connected by corresponding cylindrical positioning pins 10 (e.g., ...). Figures 2a-2c (As shown) connection.

[0029] The welding base material 11 and welding base material 2 12 are strip-shaped structures of the same size, and the lower clamp 2 and upper clamp 4 are block-shaped structures that match the shape of the welding base material 11 and welding base material 2 12.

[0030] The wedge-shaped lower clamping block 1 and the lower clamp 2, and the wedge-shaped upper clamping block 3 and the upper clamp 4 are detachably connected by connecting bolts 6.

[0031] The sample locking mechanism consists of a U-shaped clamp 5 and a locking bolt 8 (as shown in the image). Figure 4a , Figure 4b As shown); a set of U-shaped clamps 5 are fitted on the outer side of the end of the welding base material 11 and the lower clamp 2, and the corresponding U-shaped clamps 5 and the lower clamp 2 are fixedly connected by locking bolts 8; another set of U-shaped clamps 5 are fitted on the outer side of the end of the welding base material 12 and the upper clamp 4, and the corresponding U-shaped clamps 5 and the upper clamp 4 are fixedly connected by locking bolts 8.

[0032] like Figures 3a-3c As shown, the lower clamp 2 and the upper clamp 4 have the same structure, both divided into three parts along the longitudinal direction: clamping sections at both ends and connecting section in the middle; the connecting section has a groove on the side near the cross-shaped welding point sample, and a bolt hole in the middle of the groove to cooperate with the connecting bolt 6, and a washer 7 at the connection point; the U-shaped clamp 5 is sleeved on the outside of the corresponding clamping section, and the surfaces of the clamping section that contact the welding base material 11 and the welding base material 2 12 are respectively provided with anti-slip structures, and the side of the clamping section opposite to the anti-slip structure is provided with a threaded hole to cooperate with the locking bolt 8, and a washer 9 at the connection point.

[0033] The anti-slip structure is a serrated anti-slip surface.

[0034] The fatigue test fixture for cross-shaped weld point specimens of this utility model includes a wedge-shaped lower clamping block 1, a lower clamp 2, a wedge-shaped upper clamping block 3, an upper clamp 4, and a specimen locking mechanism composed of a U-shaped clamp 5, a locking bolt 8, and a washer 9. The wedge-shaped lower clamping block 1 and the lower clamp 2, and the wedge-shaped upper clamping block 3 and the upper clamp 4 are fixedly connected by connecting bolts 6 and washers 7.

[0035] In use, first, fix the spring at the lower wedge jaw of the fatigue testing machine to the cylindrical positioning pin 10 on the lower wedge clamping block 1, and fix the spring at the upper wedge jaw of the fatigue testing machine to the cylindrical positioning pin 10 on the upper wedge clamping block 3. Then, press the side of the lower chuck 2 opposite to the groove against the lower wedge clamping block 1, align the threaded hole in the groove with the threaded hole on the lower wedge clamping block 1, and connect and fix the lower chuck 2 to the lower wedge clamping block 1 using connecting bolt 6 and washer 7. Next, press the side of the upper chuck 4 opposite to the groove against the upper wedge clamping block 3, align the threaded hole in the groove with the threaded hole on the upper wedge clamping block 3, and connect and fix the upper chuck 4 to the upper wedge clamping block 3 using connecting bolt 6 and washer 7. After installation, the upper chuck 4 and the lower chuck 2 are perpendicular to each other in the horizontal direction, i.e., in a cross-shaped state.

[0036] Plate-shaped welding base material 11 and plate-shaped welding base material 2 12 are placed perpendicular to each other, and a resistance spot welding test is performed in the central area where they overlap to form a weld nugget 13, thus completing the preparation of a cross-shaped weld fatigue specimen. The cross-shaped weld fatigue specimen is shown below. Figure 5 As shown.

[0037] The weld base material 11 of the cross-shaped weld fatigue specimen is placed on top of the lower clamp 2. Specimen locking mechanisms are installed at both ends of the lower clamp 2 and the weld base material 11, respectively, using U-shaped clamps 5, locking bolts 8, and washers 9 to lock and fix the corresponding ends of the lower clamp 2 and the weld base material 11. Then, the lower clamping end of the fatigue testing machine is raised to an appropriate position so that the weld base material 12 contacts the bottom surface of the upper clamp 4. Specimen locking mechanisms are installed at both ends of the upper clamp 4 and the weld base material 12, respectively, using U-shaped clamps 5, locking bolts 8, and washers 9 to lock and fix the corresponding ends of the upper clamp 4 and the weld base material 12.

[0038] After all the above steps are completed, fatigue testing of the cross-shaped weld point specimens begins. The fatigue testing machine is started, the axial force control method is used, the test parameters are set, and the load is applied smoothly and accurately. The test ends when the specimen breaks or reaches the specified number of cycles.

[0039] The following embodiments are implemented based on the technical solution of this utility model, and provide detailed implementation methods and specific operation processes. However, the protection scope of this utility model is not limited to the following embodiments.

[0040]

Example

[0041] In this embodiment, the fatigue test fixture for the cross-shaped weld point sample includes a wedge-shaped lower clamping block 1, a lower clamp 2, a wedge-shaped upper clamping block 3, an upper clamp 4, and a sample locking mechanism.

[0042] The upper wedge-shaped clamping block 3 and the lower wedge-shaped clamping block 1 have the same structure, both being wedge-shaped blocks that mate with the wedge-shaped jaws of the fatigue testing machine. A threaded hole is formed at the center of the small end face of the wedge-shaped block. The upper clamp 4 is connected and fixed to the upper wedge-shaped clamping block 3 using connecting bolts 6 and washers 7, and the lower clamp 2 is connected and fixed to the lower wedge-shaped clamping block 1. A set (two pins per set) of symmetrically arranged cylindrical locating pins 10 is provided on the trapezoidal surfaces on both sides of the wedge-shaped block. The cylindrical locating pins 10 are used to connect the upper wedge-shaped clamping block 3 and the lower wedge-shaped clamping block 1 to the upper and lower jaws of the fatigue testing machine.

[0043] The upper chuck 4 and the lower chuck 2 have the same structure; both are rectangular blocks that mate with the cross-shaped weld point sample, and they are installed perpendicular to each other. Each rectangular block has a threaded hole at one end on the side furthest from the cross-shaped weld point sample. The side of the rectangular block closest to the cross-shaped weld point sample is divided into three areas. The central area (connecting section) has a square groove with a threaded hole at its center. The two sides of the groove are in direct contact with the cross-shaped weld point sample, and the contact surface is serrated to prevent sample movement.

[0044] The sample locking mechanism consists of a U-shaped clamp 5, a locking bolt 8, and a washer 9. A threaded hole is provided on one side of the U-shaped clamp 5.

[0045] The preparation of the cross-shaped weld spot specimen involves stacking a strip-shaped welding base material 11 and a strip-shaped welding base material 22 perpendicularly to each other, and performing a spot welding test using a resistance spot welding machine to form a weld nugget in the middle of the stacked area.

[0046] Before the test, install the fixtures and specimens. First, install the wedge-shaped upper clamping block 3 and the wedge-shaped lower clamping block 1 onto the fatigue testing machine. Then, install the upper chuck 4 and the lower chuck 2. Finally, use the specimen locking mechanism to lock and fix the weld base material 11 of the cross-shaped weld point specimen to the lower chuck 2, and the weld base material 12 of the cross-shaped weld point specimen to the upper chuck 4. After the fixtures and specimens are installed, the fatigue test of the cross-shaped weld point specimens can be carried out.

[0047] The above description is only a preferred embodiment of the present utility model, but the protection scope of the present utility model is not limited thereto. Any equivalent substitutions or changes made by those skilled in the art within the technical scope disclosed in the present utility model, based on the technical solution and concept of the present utility model, should be included within the protection scope of the present utility model.

Claims

1. A fixture for fatigue testing of cross-shaped weld point specimens, characterized in that, The device comprises a wedge-shaped lower clamping block, a lower clamp, a wedge-shaped upper clamping block, an upper clamp and a sample locking mechanism; the wedge-shaped lower clamping block is used for connecting with the wedge-shaped lower jaw of a fatigue testing machine, and the wedge-shaped upper clamping block is used for connecting with the wedge-shaped upper jaw of the fatigue testing machine; the lower clamp is installed on the top of the wedge-shaped lower clamping block, and the upper clamp is installed on the bottom of the wedge-shaped upper clamping block; a cross-shaped solder joint sample is arranged between the lower clamp and the upper clamp, and a cross-shaped structure is formed between the lower clamp and the upper clamp to match the cross-shaped solder joint sample; the cross-shaped solder joint sample is composed of a first welding base material and a second welding base material, wherein the two ends of the first welding base material are detachably fixedly connected with the corresponding ends of the lower clamp through the sample locking mechanism, and the two ends of the second welding base material are detachably fixedly connected with the corresponding ends of the upper clamp through the sample locking mechanism.

2. The jig for fatigue testing of a cross-shaped solder joint sample according to claim 1, wherein The wedge-shaped lower clamping block and the wedge-shaped lower jaw of the fatigue testing machine, and the wedge-shaped upper clamping block and the wedge-shaped upper jaw of the fatigue testing machine are connected through corresponding cylindrical positioning pins.

3. The jig for fatigue testing of a cross-shaped solder joint sample according to Claim 1, wherein The first welding base material and the second welding base material are plate-shaped structures with the same size, and the lower clamp and the upper clamp are block-shaped structures matched with the shapes of the first welding base material and the second welding base material.

4. The jig for fatigue testing of a cross-shaped solder joint sample according to Claim 1, wherein The wedge-shaped lower clamping block and the lower clamp, and the wedge-shaped upper clamping block and the upper clamp are detachably connected through connecting bolts.

5. The jig for fatigue testing of a cross-shaped solder joint sample according to claim 1, wherein The sample locking mechanism is composed of U-shaped clamps and locking bolts; one group of U-shaped clamps is sleeved on the outer side of the ends of the first welding base material and the lower clamp, and the corresponding U-shaped clamps and the lower clamp are fixedly connected through the locking bolts; the other group of U-shaped clamps is sleeved on the outer side of the ends of the second welding base material and the upper clamp, and the corresponding U-shaped clamps and the upper clamp are fixedly connected through the locking bolts.

6. The jig for fatigue testing of a cross-shaped solder joint sample according to claim 1, wherein The lower clamp and the upper clamp have the same structure and are divided into three parts along the longitudinal direction, i.e., clamping sections at both ends and a connecting section in the middle; a groove is arranged on the side of the connecting section close to the cross-shaped solder joint sample, a bolt hole is arranged in the middle of the groove to match the connecting bolt, and a gasket one is arranged at the connection; the U-shaped clamps are sleeved on the outer side of the corresponding clamping sections, the surfaces of the clamping sections in contact with the first welding base material and the second welding base material are respectively provided with anti-slip structures, a threaded hole is arranged on the side of the clamping section opposite to the anti-slip structure to match the locking bolt, and a gasket two is arranged at the connection.

7. The jig for fatigue testing of a cross-shaped solder joint sample according to claim 6, wherein The anti-slip structure is a zigzag anti-slip surface.

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