Device and method for preventing two metal welded joint test plates from being compressed during bending tests

Abstract

The present invention relates to a device and method for preventing a welding joint test plate of two metal base materials from being pressed off during a bending test, which is used when the welding joint test plate of two metal base materials is subjected to a transverse bending test. The device comprises a clamping plate for clamping the welding joint test plate and a circular pressing roller for pressing the welding joint test plate. A rectangular hole for inserting the welding joint test plate is provided in the middle of the clamping plate, and a circular hole for inserting a steel wire rope is provided next to the rectangular hole. Both ends of the steel wire rope and both ends of the welding joint test plate are fixed on two clamping plates, the steel wire rope is fixed on the clamping plate by a top wire, and the welding joint test plate is fixed on the clamping plate by a clamping screw. A positioning pin is mounted on the steel wire rope, and a platform with a pin hole is processed at the lower part of one end of the circular pressing roller. The pin hole cooperates with the positioning pin. The device has the advantages of safety, reliability, convenience in operation, economy, practicality and cost saving, and ensures that the bending test is carried out normally and solves the problem of test plate pressing off during the bending test of the circular pressure head.

Description

Technical Field

[0001] The present invention belongs to the technical field of metal material testing and analysis, and in particular relates to a device and method for preventing a test plate of a welded joint of two metal base materials from being pressed off during a transverse bending test, thereby ensuring that the bending test is carried out normally and solving the problem of test plate pressing off during a circular indenter bending test. Background Art

[0002] The container manufacturing industry often needs to weld two materials together, such as welding stainless steel to ordinary carbon steel, and welding steel to copper. According to relevant standards, the mechanical properties of the welded joints of the two metal base materials must be tested.

[0003] The welding joint test plate bending test standard GB / T 2653-2008 "Welding joint bending test method" stipulates two test methods, one of which is the more commonly used method, the circular indenter bending test, also known as the three-point bending test, and the bending test machine suitable for this test method is also the most widely used. However, this bending test method may cause the test plate to deviate during the test. Especially for welded joints of two base materials, when the strength and hardness differences between the base materials on both sides of the weld and between the weld joint and the weld heat affected zone are obvious, the deviating phenomenon is more likely to occur. During the bending test, the indenter slides to the side with lower strength and hardness of the base material, and the weld does not reach the specified bending deformation, resulting in test failure. The deviating phenomenon not only wastes the test plate materials and test plate production time, but also directly affects the normal production due to the inability to obtain relevant welding performance data. Therefore, it is necessary to find an effective method to solve the deviating problem of the test plate in the circular indenter bending test using an ordinary three-point bending test machine. Summary of the invention

[0004] The purpose of the present invention is to overcome the shortcomings of the prior art and provide a device that can prevent the test plate from sliding to one side during the bending process, always keep the relative position of the pressure head and the center of the test plate welding joint unchanged, ensure the normal progress of the bending test, and solve the problem of test plate deflection during the bending test with a circular pressure head. The present invention belongs to the field of metal material testing and analysis technology, and in particular, relates to a device and method for preventing deflection of a test plate of a welded joint of two metal base materials during a bending test.

[0005] The purpose of the present invention is achieved as follows: a device for preventing two metal base materials from being pressed off during a bending test of a welding joint test plate, comprising two parallel long strip-shaped clamping plates for clamping the welding joint test plate and a circular pressure roller for pressing the welding joint test plate, a rectangular hole for inserting a welding joint test plate of corresponding specifications is opened in the middle of the clamping plate, a circular hole for inserting a steel wire rope is opened next to the rectangular hole, both ends of the steel wire rope and both ends of the welding joint test plate are fixed on the two clamping plates, the steel wire rope is fixed on the clamping plates by a top wire, the welding joint test plate is fixed on the clamping plates by a clamping screw, a positioning pin is set in the middle position of the steel wire rope, and is reliably fastened to the steel wire rope by a top wire, and the axial direction of the positioning pin is perpendicular to the length direction of the clamping plate; a platform with a pin hole is processed at the lower part of one end of the circular pressure roller, the pin hole cooperates with the positioning pin, and after the welding joint test plate is installed in the square holes of the two clamping plates, the pin shaft center of the positioning pin corresponds to the welding joint center of the welding joint test plate.

[0006] The steel wire rope is firstly straightened manually and then fixed on the two clamping plates by means of a clamping screw.

[0007] The weld joint test plate is located above the lower support roller.

[0008] After the positioning pin is inserted into the pin hole at the lower part of the circular pressure roller, the center of the welding joint of the welding joint test plate and the circular pressure roller are in the same vertical plane.

[0009] The length and width of the square holes of the two clamping plates are larger than the cross-sectional dimensions of the weld joint test plate, so that the weld joint test plate can be smoothly loaded and unloaded.

[0010] The diameter of the steel wire rope is the same as the thickness of the weld joint test plate, and the length of the steel wire rope should be greater than or equal to the length of the weld joint test plate.

[0011] The steel wire rope is a flexible structure.

[0012] A method for preventing the test plate of a welded joint of two metal base materials from being pressed off during a bending test, characterized in that the device for preventing the test plate of a welded joint of two metal base materials from being pressed off during a bending test is used in accordance with the following steps:

[0013] Step 1) Install the weld joint test plate into the square holes of the two clamping plates, and fix the two ends of the weld joint test plate in the rectangular holes of the two clamping plates by tightening screws;

[0014] Step 2) First, manually straighten the wire rope, and fix the two ends of the wire rope in the round holes of the two clamping plates through the wire rope top wire;

[0015] Step 3) Fix the positioning pin on the wire rope through the positioning pin top screw, and adjust the position of the positioning pin on the wire rope through the positioning pin top screw to ensure that the axial direction of the positioning pin is perpendicular to the length direction of the clamping plate, and also ensure that the weld center of the weld joint test plate corresponds to the pin axis of the positioning pin and is in the same plane;

[0016] Step 4), place the weld joint test plate on the two lower support rollers, match the pin hole on the lower platform of one end of the circular pressure roller with the positioning pin, slowly move the circular pressure roller downward, insert the positioning pin into the pin hole at the lower part of one end of the circular pressure roller, so that the center of the weld joint of the weld joint test plate and the circular pressure roller are in the same vertical plane, and the length direction of the weld joint test plate is perpendicular to the axis direction of the circular pressure roller;

[0017] Step 5), move the circular pressing roller downward again, so that the bottom of the circular pressing roller, the weld joint test plate, and the upper part of the lower support roller are in contact with each other, and at this time, the positioning pin is fully inserted into the pin hole of the circular pressing roller, but the weld joint test plate does not bend or deform;

[0018] Step 6), further move the circular pressure roller downward, and the weld joint test plate begins to bend and deform; when the weld joint test plate is compressed and bent, the steel wire rope undergoes the same deformation as the weld joint test plate; since the base materials on both sides of the weld joint test plate are different and have different strengths, after being subjected to compressive bending force, the side with lower base material strength will first bend and deform, and the circular pressure roller has a tendency to slide to that side. Since the positioning pin is inserted into the pin hole at the bottom of the circular pressure roller, the positioning pin, the steel wire rope, the clamping plate, the weld joint test plate and the circular pressure roller form a relatively fixed position relationship, and the steel wire rope will generate a tensile force opposite to the offset trend of the weld joint test plate. Since the steel wire rope generates a tensile force opposite to the offset trend of the weld joint test plate, the offset of the weld seam center of the weld joint test plate relative to the circular pressure roller is limited. Since the weld joint center of the weld joint test plate is always directly below the circular pressure roller during the bending process, the weld seam produces a specified bending deformation, thereby ensuring the smooth progress of the bending test;

[0019] Step 7) After the bending test is completed, lift the circular pressure roller, the positioning pin is disengaged from the pin hole of the circular pressure roller, the wire rope is in a free state, and the device and the weld joint test plate are taken out from the testing machine together, and the clamping screw is loosened. The clamping plate can slide freely on the weld joint test plate after bending, and the two clamping plates are taken out from the weld joint test plate respectively, and then the bending result of the weld joint test plate can be evaluated.

[0020] The present invention has the following positive effects: it can prevent the test plate from sliding to one side during the bending process, always keep the relative position of the pressure head and the center of the test plate welding joint unchanged, ensure the normal progress of the bending test, solve the problem of test plate compression deviation during the circular pressure head bending test, and has the advantages of safety, reliability, easy operation, economy and practicality, and cost saving. It not only does not cause waste of test plate materials and test plate production time, but also can obtain relevant welding performance data to ensure the normal progress of production. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a structural schematic diagram of a bimetallic welded joint test plate.

[0022] Figure 2 It is a schematic diagram of the bimetallic welded joint test plate after deflection.

[0023] Figure 3 It is a structural schematic diagram of the present invention.

[0024] Figure 4 yes Figure 3 Top view of the .

[0025] Figure 5 yes Figure 3 Left view through center.

[0026] Figure 6 It is a structural cross-sectional view of the clamping plate 3.

[0027] In the figure, 1. welding joint test plate, 2. round pressure roller, 3. clamping plate, 4. positioning pin, 5. wire rope, 6. wire rope top wire, 7. positioning pin top wire, 8. lower support roller (the clamp provided by the bending test machine), 9. clamping screw. DETAILED DESCRIPTION

[0028] like Figure 1 As shown, in Figure 1 The welded joint test plate is used for transverse bending test. When the base materials on both sides are different and the performance difference is obvious, there will be Figure 2 The phenomenon of bending test failure is caused by the indenter. Analysis shows that during the bending process, the bending deformation area of ​​the test plate will slide to the side with lower strength and hardness of the parent material. If a device is invented to prevent the test plate from sliding to one side during the bending process and always keep the relative position of the indenter and the center of the test plate weld joint unchanged, the normal bending test can be ensured, and the problem of test plate deflection during the round indenter bending test can be solved.

[0029] like Figure 3 , 4 , 5, and 6, Figure 3It is both the working principle diagram of the present invention and the structural schematic diagram of the present invention. The present invention discloses a device for preventing the welding joint test plate of two metal base materials from being pressed off during the bending test, comprising two parallel long strip clamping plates 3 for clamping the welding joint test plate 1 and a circular pressing roller 2 for pressing the welding joint test plate 1, the two clamping plates 3 are placed in parallel longitudinally, a rectangular hole for inserting the welding joint test plate 1 of corresponding specifications is opened in the middle of the clamping plates 3, and a circular hole for inserting the wire rope 5 is opened next to the rectangular hole, that is, a rectangular hole and a circular hole are processed on the clamping plates 3, the rectangular hole is used to insert the welding joint test plate 1 of corresponding specifications, and the circular hole is used to insert the wire rope 5; both ends of the wire rope 5 and the welding joint test plate 1 are fixed on the two clamping plates 3, that is, the wire rope 5 is fixed in the circular hole on the clamping plates 3 by the wire rope top wire 6, and the welding joint test plate 1 is fixed in the rectangular hole on the clamping plates 3 by the clamping screw 9; after being fixed, the wire rope 5 and the welding joint test plate 1 are parallel to each other. A positioning pin 4 is installed in the middle position of the wire rope 5 and is reliably fastened to the wire rope 5 through the positioning pin top screw 7, and the axial direction of the positioning pin 4 is perpendicular to the length direction of the clamping plate 3; a platform with a pin hole is processed at the lower part of one end of the circular pressure roller 2, and the pin hole cooperates with the positioning pin 4. After the welding joint test plate 1 is installed in the square holes of the two clamping plates 3, the pin shaft center of the positioning pin 4 corresponds to the welding joint center of the welding joint test plate 1.

[0030] The diameter of the steel wire rope 5 is the same as the thickness of the weld joint test plate 1, and the length is the length of the weld joint test plate 1. A clamping plate 3 is fixed at each end of the steel wire rope 5, and the clamping plate 3 and the steel wire rope 5 are reliably fastened with the steel wire rope top screw 6, and the length direction of the clamping plate 3 is kept consistent after fastening. A positioning pin 4 is set in the middle position of the steel wire rope 5, and is reliably fastened with the positioning pin top screw 7, and the axial direction of the pin 4 is perpendicular to the length direction of the clamping plate 3. A platform and a pin hole are processed at the lower part of one end of the circular pressure roller 2, and the pin hole has a matching relationship with the outer diameter of the positioning pin 4.

[0031] like Figure 2 As shown, install the welding joint test plate 1 into the square holes of the two clamping plates 3, so that the pin shaft center of the positioning pin 4 corresponds to the welding joint center of the welding joint test plate 1, first manually straighten the wire rope 5, and then use the tightening screw 9 to fix the welding joint test plate and the two clamping plates 3.

[0032] As shown in the figure, a method for preventing the test plate of a welded joint of two metal base materials from being pressed off during a bending test is performed using the device for preventing the test plate of a welded joint of two metal base materials from being pressed off during a bending test according to the following steps:

[0033] Step 1), install the weld joint test plate 1 into the square holes of the two clamping plates 3, and fix the two ends of the weld joint test plate 1 in the rectangular holes of the two clamping plates 3 by tightening screws 9;

[0034] Step 2), first manually straighten the wire rope 5, and fix the two ends of the wire rope 5 in the round holes of the two clamping plates 3 through the wire rope top wire 6;

[0035] Step 3), fix the positioning pin 4 on the wire rope 5 through the positioning pin top screw 7, and adjust the position of the positioning pin 4 on the wire rope 5 through the positioning pin top screw 7 to ensure that the axial direction of the positioning pin 4 is perpendicular to the length direction of the clamping plate 3, and also ensure that the weld center of the weld joint test plate 1 corresponds to the pin axis of the positioning pin 4 and is in the same plane;

[0036] Step 4), place the weld joint test plate 1 on the two lower support rollers 8, match the pin hole on the lower platform of one end of the circular pressure roller 2 with the positioning pin 4, slowly move the circular pressure roller 2 downward, so that the positioning pin 4 is inserted into the pin hole at the lower part of one end of the circular pressure roller 2, so that the center of the weld joint of the weld joint test plate 1 and the circular pressure roller 2 are in the same vertical plane, and the length direction of the weld joint test plate 1 is perpendicular to the axis direction of the circular pressure roller 2;

[0037] Step 5), the circular pressing roller 2 is moved downward again, so that the bottom of the circular pressing roller 2, the weld joint test plate 1, and the upper part of the lower support roller 8 are in contact with each other, and at this time, the positioning pin 4 is completely inserted into the pin hole of the circular pressing roller 2, but the weld joint test plate (1) does not bend or deform;

[0038] Step 6), further move the circular pressure roller 2 downward, and the weld joint test plate 1 begins to bend and deform; when the weld joint test plate 1 is compressed and bent, the steel wire rope 5 undergoes the same deformation as the weld joint test plate 1; since the base materials on both sides of the weld joint test plate 1 are different and have different strengths, after being subjected to compressive bending force, the side with lower base material strength first bends and deforms, and the circular pressure roller 2 tends to slide to that side. Since the positioning pin 4 is inserted into the pin hole at the bottom of the circular pressure roller 2, the positioning pin 4, the steel wire rope 5, the clamping plate 3, the weld joint test plate 1 and the circular pressure roller 2 form a relatively fixed position relationship, and the steel wire rope 5 will generate a tensile force opposite to the offset trend of the weld joint test plate 1. Since the steel wire rope 5 generates a tensile force opposite to the offset trend of the weld joint test plate 1, the offset of the weld center of the weld joint test plate 1 relative to the circular pressure roller 2 is limited. Since the weld joint center of the weld joint test plate 1 is always directly below the circular pressure roller 2 during the bending process, the weld produces a specified bending deformation, thereby ensuring the smooth progress of the bending test;

[0039] Step 7), after the bending test is completed, lift the circular pressure roller 2, the positioning pin 4 is disengaged from the pin hole of the circular pressure roller 2, the wire rope 5 is in a free state, and the device and the weld joint test plate 1 are taken out from the testing machine together, and the clamping screw 9 is loosened. The clamping plate 3 can slide freely on the weld joint test plate 1 after bending, and the two clamping plates 3 are taken out from the weld joint test plate 1 respectively, and then the bending result of the weld joint test plate 1 can be evaluated.

[0040] When in use, first adjust the position and parameters of the bending test machine fixture, and place the weld joint test plate 1 assembled with the device on the lower support roller 8. Slowly move the circular pressing roller 2 downward to insert the positioning pin 4 into the pin hole at the bottom of the circular pressing roller 2, so that the center of the weld joint of the weld joint test plate 1 and the circular pressing roller 2 are in the same vertical plane.

[0041] The circular roller 2 is continuously moved downward, and the weld joint test plate 1 is bent and deformed, and the steel wire rope 5 is bent and deformed in the same manner as the weld joint test plate 1. Due to the different base materials on both sides, the weld joint test plate 1 tends to deviate toward one side of the base material. Since the positioning pin 4 is inserted into the pin hole at the bottom of the circular roller 2, the positioning pin 4, the steel wire rope 5, the clamping plate 3, the weld joint test plate 1 and the circular roller 2 have a relatively fixed position relationship, so the steel wire rope 5 will generate a pulling force opposite to the deviation trend of the weld joint test plate 1.

[0042] Since the steel wire rope 5 generates a tension opposite to the deviation trend of the weld joint test plate 1, the deviation of the weld center of the weld joint test plate 1 relative to the circular pressure roller 2 is limited, thereby ensuring the normal progress of the bending deformation test of the weld joint test plate 1.

[0043] The most significant feature of the present invention is that, in view of the characteristics of bending deformation and stress during the bending test of the welding joint test plate, a relatively simple device is used to limit the relative position of the welding joint test plate 1 and the circular pressure roller 2, while at the same time ensuring that the welding joint test plate 1 can bend and deform freely.

[0044] The length and width of the square hole of the clamp plate 3 are larger than the cross-sectional dimensions of the test specimen, so that the weld joint test plate 1 can be smoothly loaded and unloaded. In order to ensure that the weld joint test plate 1 and the wire rope 5 have the same bending radius and avoid generating internal stress to each other, the diameter of the wire rope 5 should be selected to be substantially the same as the thickness dimension of the weld joint test plate 1. The length of the wire rope 5 should be roughly equal to the length of the weld joint test plate 1, and the two clamp plates 3 should be fixed at positions close to both ends. This position should ensure that when the wire rope 5 is in a straightened state, there will be no interference between the clamp plates 3 and the circular pressure roller 2 and the lower support roller 8 during the bending test. The positioning pin 4 is fixed on the wire rope 5 and is located in the middle of the two clamp plates 3. The axis of the pin should be roughly perpendicular to the length direction of the two clamp plates 3 to facilitate manual assistance in inserting it into the pin hole at the lower end of one end of the circular pressure roller 2.

[0045] When inserting the welding joint test plate 1 into the rectangular holes of the two clamping plates 3 and pressing them tightly, two points need to be noted: 1. Ensure that the weld center of the welding joint test plate 1 corresponds to the pin axis of the positioning pin 4 and is in the same plane; 2. The wire rope is in a manually straightened state.

[0046] When bending, as with conventional bending tests, the distance between the two lower support rollers 8 (which are the fixtures provided by the bending test machine) should be adjusted first, the round pressure roller 2 should be installed on the test machine, and the equipment parameters should be adjusted. Then, according to the above requirements, the welded joint test plate 1 should be fixed in the two clamping plates 3.

[0047] At the beginning of the test, the weld joint test plate 1 fixed with the device is placed on the two lower support rollers 8, the circular pressure roller 2 is slowly moved down, and the positioning pin 4 is manually inserted into the pin hole at the lower end of the circular pressure roller 2, and the length direction of the weld joint test plate 1 is perpendicular to the axis direction of the circular pressure roller 2. The circular pressure roller 2 is then moved down so that the bottom of the circular pressure roller 2, the weld joint test plate 1, and the upper part of the lower support roller 8 are in contact with each other. At this time, the positioning pin 4 is completely inserted into the pin hole of the circular pressure roller 2, but the weld joint test plate 1 does not bend or deform.

[0048] The circular pressure roller 2 is further moved downward, and the weld joint test plate 1 begins to bend and deform. When the weld joint test plate 1 is compressed and bent, the steel wire rope 5 undergoes the same deformation as the weld joint test plate 1. Since the base materials on both sides of the weld joint test plate 1 are different and have different strengths, after being subjected to compressive bending force, the side with lower base material strength will first bend and deform, and the circular pressure roller 2 tends to slide to that side. Since the positioning pin 4 is inserted into the pin hole at the bottom of the circular pressure roller 2, the positioning pin 4, the steel wire rope 5, the clamping plate 3, the weld joint test plate 1 and the circular pressure roller 2 form a relatively fixed position relationship, so the steel wire rope 5 will generate a tensile force opposite to the deviation trend of the weld joint test plate 1. Since the steel wire rope 5 generates a tensile force opposite to the deviation trend of the weld joint test plate 1, the deviation of the weld center of the weld joint test plate 1 relative to the circular pressure roller 2 is limited. Since the weld joint center of the weld joint test plate 1 is always directly below the circular pressure roller 2 during the bending process, the weld produces a specified bending deformation, thereby ensuring the smooth progress of the bending test.

[0049] After the bending test is completed, the circular pressure roller 2 is lifted, the positioning pin 4 is disengaged from the pin hole of the circular pressure roller 2, and the wire rope 5 is in a free state. The device and the welded joint test plate 1 are taken out of the testing machine together, and the clamping screw 9 is loosened. The clamping plate 3 can slide freely on the welded joint test plate 1 after bending, and the two clamping plates 3 are taken out from the welded joint test plate 1 respectively. After that, the bending result of the welded joint test plate 1 can be evaluated.

[0050] The steel wire rope 5 is a flexible structure and can be bent repeatedly for use, so the device has a relatively stable performance.

[0051] Due to the different thicknesses of welding materials, different thicknesses of the welding joint test plate 1, and different bending radii of the circular pressure roller 2, it is necessary to manufacture a series of devices based on the principle of the invention to meet the bending test requirements of welding joint samples of different thicknesses.

Claims

1. A device for preventing a test plate of a welded joint of two metal base materials from being pressed off during a bending test, comprising two parallel long strip clamps (3) for clamping the welded joint test plate (1) and a circular pressing roller (2) for pressing the welded joint test plate (1), characterized in that: A rectangular hole for inserting a welding joint test plate (1) of corresponding specifications is opened in the middle of the clamping plate (3), and a round hole for inserting a steel wire rope (5) is opened next to the rectangular hole. Both ends of the steel wire rope (5) and both ends of the welding joint test plate (1) are fixed on the two clamping plates (3). The steel wire rope (5) is fixed on the clamping plate (3) by a steel wire rope top wire (6). The welding joint test plate (1) is fixed on the clamping plate (3) by a clamping screw (9). A positioning pin (4) is set in the middle position of the steel wire rope (5) and is reliably fastened to the steel wire rope (5) by a positioning pin top wire (7). The axial direction of the positioning pin (4) is perpendicular to the length direction of the clamping plate (3); a positioning pin (4) is added at the lower part of one end of the circular pressure roller (2). The tool has a platform with a pin hole, the pin hole cooperates with the positioning pin (4), after the welding joint test plate (1) is installed in the square holes of the two clamping plates (3), the pin shaft center of the positioning pin (4) corresponds to the welding joint center of the welding joint test plate (1); the steel wire rope (5) is manually straightened and then fixed to the two clamping plates (3) by a clamping screw (9); the welding joint test plate (1) is located above the lower support roller (8); after the positioning pin (4) is inserted into the pin hole at the bottom of the circular pressure roller (2), the welding joint center of the welding joint test plate (1) and the circular pressure roller (2) are in the same vertical plane; the length and width of the square holes of the two clamping plates (3) are larger than the cross-sectional dimensions of the welding joint test plate (1), so that the welding joint test plate (1) can be smoothly loaded and unloaded; The diameter of the steel wire rope (5) is the same as the thickness of the weld joint test plate (1), and the length of the steel wire rope (5) should be greater than or equal to the length of the weld joint test plate (1); the steel wire rope (5) is a flexible structure.

2. A method for preventing the test plate of a welded joint of two metal base materials from being compressed during a bending test, characterized in that: The device for preventing the bending test of the test plate of the welded joint of two metal base materials according to claim 1 is used in accordance with the following steps: Step 1), install the weld joint test plate (1) into the square holes of the two clamping plates (3), and fix the two ends of the weld joint test plate (1) in the rectangular holes of the two clamping plates (3) by means of tightening screws (9); Step 2), first manually straighten the steel wire rope (5), and fix the two ends of the steel wire rope (5) in the round holes of the two clamping plates (3) through the steel wire rope top wire (6); Step 3), fix the positioning pin (4) on the steel wire rope (5) by means of the positioning pin top screw (7), and adjust the position of the positioning pin (4) on the steel wire rope (5) by means of the positioning pin top screw (7), ensure that the axial direction of the positioning pin (4) is perpendicular to the length direction of the clamping plate (3), and also ensure that the weld center of the weld joint test plate (1) corresponds to the pin axis of the positioning pin (4) and is in the same plane; Step 4), placing the weld joint test plate (1) on top of the two lower support rollers (8), matching the pin hole on the lower platform of one end of the circular pressure roller (2) with the positioning pin (4), slowly moving the circular pressure roller (2) downward, so that the positioning pin (4) is inserted into the pin hole at the lower part of one end of the circular pressure roller (2), so that the center of the weld joint of the weld joint test plate (1) and the circular pressure roller (2) are in the same vertical plane, and at the same time, the length direction of the weld joint test plate (1) is perpendicular to the axial direction of the circular pressure roller (2); Step 5), the circular pressing roller (2) is moved downward again, so that the bottom of the circular pressing roller (2), the weld joint test plate (1), and the upper part of the lower support roller (8) are in contact with each other, and at this time, the positioning pin (4) is completely inserted into the pin hole of the circular pressing roller (2), but the weld joint test plate (1) does not bend or deform; Step 6), further move the circular pressure roller (2) downward, and the weld joint test plate (1) begins to bend and deform; when the weld joint test plate (1) is compressed and deformed, the steel wire rope (5) undergoes the same deformation as the weld joint test plate (1); since the base materials on both sides of the weld joint test plate (1) are different and have different strengths, after being compressed and bent, the side with lower base material strength first bends and deforms, and the circular pressure roller (2) tends to slide toward this side. Since the positioning pin (4) is inserted into the pin hole at the bottom of the circular pressure roller (2), the positioning pin (4), the steel wire rope (5), the clamping plate (3), The weld joint test plate (1) and the circular pressure roller (2) form a relatively fixed positional relationship, and the steel wire rope (5) will generate a tensile force opposite to the deflection trend of the weld joint test plate (1). Since the steel wire rope (5) generates a tensile force opposite to the deflection trend of the weld joint test plate (1), the deflection of the weld seam center of the weld joint test plate (1) relative to the circular pressure roller (2) is limited. Since the weld joint center of the weld joint test plate (1) is always located directly below the circular pressure roller (2) during the bending process, the weld seam generates a specified bending deformation, thereby ensuring the smooth progress of the bending test; Step 7) After the bending test is completed, lift the circular pressure roller (2), the positioning pin (4) is removed from the pin hole of the circular pressure roller (2), the wire rope (5) is in a free state, and the device and the weld joint test plate (1) are taken out from the testing machine together, and the clamping screw (9) is loosened. The clamping plate (3) can slide freely on the weld joint test plate (1) after bending. The two clamping plates (3) are taken out from the weld joint test plate (1) respectively, and then the bending result of the weld joint test plate (1) can be evaluated.

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