Tensile sample scale distance marking device and tensile method

Abstract

The invention discloses a tensile sample scale distance marking device and a tensile method. The tensile sample scale distance marking device comprises a bearing mechanism, and the bearing mechanism comprises two symmetrically-arranged driving parts; the two stretching mechanisms are symmetrically arranged, each stretching mechanism comprises a synchronous assembly fixedly connected with the driving part, a plurality of pushing assemblies and connecting assemblies are installed in the synchronous assembly, the synchronous assembly comprises a stretching table, the connecting assemblies are provided with detachable fixing assemblies, and the fixing assemblies fixedly clamp a sample. According to the invention, a plurality of samples can be subjected to tensile test at the same time, when any one sample is broken, the clamping part for fixing the broken sample can be separated from the tensile table, the rest of samples can be subjected to tensile test continuously, and finally, the moving distances of the two symmetrically arranged clamping parts are added to determine and record the fracture distance of the tensile sample. Not only is the operation simple, but also the tensile test efficiency of the sample is greatly improved.

Description

Technical Field

[0001] The invention belongs to the technical field of mechanical property detection, and in particular relates to a tensile specimen gauge marking device and a tensile method. Background Art

[0002] The test to determine a series of properties of materials under tensile load is also called tensile test. It is one of the basic methods for testing the mechanical properties of materials, among which the tensile test refers to the test method for determining the properties of materials under axial tensile load.

[0003] Before and after the tensile test of the material, a measuring device will be used to measure the gauge length of the tensile specimen. The data obtained can be used to determine the material's elastic limit, elongation, elastic modulus, proportional limit, area reduction, tensile strength, yield point, yield strength and other tensile performance indicators. Therefore, the accuracy and stability of the measuring device are critical to testing whether the material meets the specified standards and studying the performance of the material.

[0004] The existing stretching device can only perform a tensile test on a single material. When multiple materials need to be tested, it takes a lot of time and manpower to perform the tensile test, which is very inconvenient. Summary of the invention

[0005] The present invention aims at solving the problems in the prior art and proposes the following technical solutions: Tensile specimen gauge marking device, comprising: A bearing mechanism, the bearing mechanism comprising two symmetrically arranged driving parts; Two symmetrically arranged stretching mechanisms, the stretching mechanism comprising a synchronous component fixedly connected to the driving part, a plurality of pushing components and connecting components are installed inside the synchronous component, and the synchronous component comprises a stretching table, the connecting component is installed with a detachable fixing component, and the fixing component is fixedly clamped to hold the sample; The connection assembly includes a plug-in block, the outer wall of which is fixedly connected to a connecting plate, the connecting plate is equipped with a detachable plug-in rod and is installed on the inner wall of the stretching table through a sliding portion, and one end of the plug-in rod is fixedly connected to a circular frame that matches the second trapezoidal block; The fixing assembly includes a plug-in board plugged into the plug-in block, one side of the plug-in board extends to the outside of the stretching table and is fixedly connected with a clamping portion, and the sample is fixed in the clamping portion; The driving part drives the synchronous component to move to perform a tensile test on the sample fixed in the clamping part. When the sample breaks, the trapezoidal block moves to one side of the circular frame to control the plug-in block to move away from the plug-in board, so that the broken sample is retained at the position where the break occurs.

[0006] As a preferred embodiment of the above technical solution, the pushing component includes: A pressing rod 2, wherein the pressing rod 2 is movably sleeved in the inner ring of the stretching table, the pressing rod 2 is fixedly connected to a trapezoidal block 2 at one end located inside the stretching table, the inclined portion of the trapezoidal block 2 is fitted with the inner wall of the circular frame, and both sides of the trapezoidal block 2 are fixedly connected to sliding sleeves, the inner ring movable sleeve of the sliding sleeve is provided with a guide rod 2, the two ends of the guide rod 2 are respectively fixedly connected to the inner walls of the two sides of the stretching table, one side of the sliding sleeve is fixedly connected to an elastic part 2, and the end of the elastic part 2 away from the sliding sleeve is fixedly connected to the inner wall of the stretching table.

[0007] As a preferred embodiment of the above technical solution, the sliding part includes: A guide rod three, wherein the guide rod three is movably sleeved in the inner ring of the connecting plate, and the two ends of the guide rod three are respectively fixedly connected to the inner walls of the two sides of the stretching table, one side of the connecting plate is fixedly connected with an elastic part three, and one end of the elastic part three away from the connecting plate is fixedly connected to the inner wall of the stretching table, the outer ring fixed sleeve of the plug-in rod is provided with a baffle, the end of the plug-in rod away from the circular frame passes through the connecting plate and is threadedly connected with a threaded sleeve, and the connecting plate is located between the baffle and the threaded sleeve.

[0008] As a preferred embodiment of the above technical solution, the synchronization component includes: A pressing rod, one end of which is movably sleeved in the inner ring of the stretching table, and the other end of the inner ring of the pressing rod is movably sleeved with a guide rod, the side of the stretching table away from the clamping part is fixedly connected to the driving part, the end of the guide rod away from the pressing rod is fixedly connected to the stretching table, an elastic part 1 fixedly connected to the guide rod 1 is arranged inside the pressing rod, and a trapezoidal block 1 that contacts the trapezoidal block 2 is fixedly connected to the outer wall of the pressing rod.

[0009] The stretching method of the tensile specimen gauge marking device according to any one of the above items comprises the following steps: S10. Sample marking Select multiple samples of the same material for marking, using two or more marking methods; S20, tensile test Fixing multiple specimens on a tensile mechanism for tensile testing; S30. Collect data Collect the tensile strength data of each specimen and test whether the data conforms to the normal distribution; S40, Model Building A normal distribution model is established based on the tensile strength data of multiple samples, and its function is: ƒ Among them, x is the variable, μ is the mean, and σ is the standard deviation; S50, result output The optimal labeling method was determined based on the S40 normal distribution model.

[0010] As a preferred embodiment of the above technical solution, in S10, sample marking, the marking method adopts a laser method, a punching method, or the like.

[0011] As a preferred embodiment of the above technical solution, in S10, the mark of the gauge length in the sample marking is used to calculate the elongation after fracture. The calculation formula of the elongation after fracture is A%= / L0×100%, L U is the gauge length after fracture, L0 is the original gauge length, the original gauge length L0=25mm, and the specimen marking deviation L0=25mm±0.25mm.

[0012] As a preferred embodiment of the above technical solution, S20, in the tensile test: S21, fixing the sample, fixing the multiple samples between the two stretching tables by means of multiple symmetrically arranged clamping parts; S22, stretching the sample, starting the two driving parts at the same time to drive the two stretching tables to move away from each other, and performing a stretching test on multiple samples located in the middle at the same time; S23, when any sample breaks, the driving unit is turned off, and the corresponding pressing rod 2 is pushed to move the trapezoidal block 2 to the side close to the circular frame. The plug-in block can be driven away from the plug-in board through the friction between the hypotenuse of the trapezoidal block 2 and the circular frame. When the plug-in block is completely separated from the plug-in board, the clamping part fixing the broken sample will be separated from the stretching table. The driving unit is started again to continue the stretching test of the remaining samples. The moving distances of the two symmetrically arranged clamping parts are added together to determine the distance at which the tensile sample breaks, and the distance is recorded. As a preferred embodiment of the above technical solution, in S30, in the data collection, multiple comparisons are performed to further determine whether there is a difference between the means of the two groups, and the normal distribution of the two samples with different labeling methods is compared by Levene's test to test whether the variances are the same.

[0013] As a preferred embodiment of the above technical solution, in S30, in collecting data, the deviation of data under two different methods is compared by using an F test to determine whether there is a significant difference in precision.

[0014] The beneficial effects of the present invention are: 1. The present invention can perform tensile tests on multiple samples at the same time. When any sample breaks, the clamping part that fixes the broken sample can be separated from the stretching table, and the remaining samples can continue to be tensile tested. Finally, the moving distances of the two symmetrically arranged clamping parts are added to determine the distance at which the tensile sample breaks and record it. This is not only simple to operate, but also greatly improves the tensile test efficiency of the sample. 2. The present invention determines the influence of different markings on the tensile test of the specimen by comparing different marking methods, and selects the optimal marking method. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 What is shown is a schematic diagram of the structure of the tensile specimen gauge marking device in the embodiment; Figure 2 What is shown is a schematic diagram of the structure of the stretching mechanism in the embodiment; Figure 3 What is shown is a schematic diagram of the structure of the synchronization component in the embodiment; Figure 4 What is shown is a schematic diagram of the structure of the pushing component and the fixing component in the embodiment; Figure 5 What is shown is a schematic diagram of the structure of the connecting component and the fixing component in the embodiment; Figure 6 What is shown is a schematic diagram of the structure of the pushing component and the connecting component in the embodiment; Figure 7 What is shown is a schematic diagram of the structure of the connection assembly in the embodiment; Figure 8 What is shown is a schematic diagram of the structure of the fixing assembly in the embodiment; Fig. 9 Shown is a schematic diagram of an equal variance test in an embodiment.

[0016] Description of reference numerals: 100, bearing mechanism; 101, bearing platform; 102, driving unit; 200, stretching mechanism; 210, synchronization component; 211, stretching platform; 212, pressing rod 1; 213, guide rod 1; 214, elastic part 1; 215, trapezoidal block 1; 220, pushing component; 221, pressing rod 2; 222, trapezoidal block 2; 223, sliding sleeve; 224, guide rod 2; 225, elastic part 2; 230, Connecting assembly; 231, plug-in block; 232, connecting plate; 233, plug-in rod; 234, circular frame; 235, baffle; 236, thread sleeve; 237, guide rod three; 238, elastic part three; 240, fixing assembly; 241, plug-in plate; 242, moving block; 244, clamping seat; 245, fixing frame; 246, screw rod; 247, upper clamping plate; 248, guide rod four; 249, rubber bump. DETAILED DESCRIPTION

[0017] In order to make the purpose, technical solution and advantages of the embodiments of the present invention more clear, the technical solution of the present invention will be clearly and completely described below in conjunction with the embodiments.

[0018] GB / T 228.1 and GB / T 228.2 stipulate that the original gauge length can be marked with a small mark, a thin line or a thin ink line, and the notch that causes premature fracture shall not be used as a mark. The marking of the original gauge length should be accurate to ±1%.

[0019] ASTM E8 stipulates that the mark can be lightly drawn with a dotting machine, a compass, or with the recommended ink. The marking methods for elongation after fine fracture include the line method and the dot method.

[0020] Example 1 like Figure 1 , Figure 2 , Figure 5 , Figure 7 and Figure 8 As shown, the tensile specimen gauge length marking device comprises a bearing mechanism 100 and two symmetrically arranged stretching mechanisms 200, the bearing mechanism 100 comprises two symmetrically arranged driving parts 102 and a bearing platform 101, the driving part 102 adopts a cylinder, the outer surface of the bearing platform 101 is provided with scale lines, the driving part 102 is fixed on the top of the bearing platform 101, the stretching mechanism 200 comprises a synchronous component 210 fixedly connected to the driving part 102, a plurality of pushing components 220 and a connecting component 230 are installed inside the synchronous component 210, and the synchronous component 210 comprises a stretching platform 211, the connecting component 230 is installed There is a detachable fixing component 240, which fixes and clamps the sample. The connecting component 230 includes a plug-in block 231, and the outer wall of the plug-in block 231 is fixedly connected to a connecting plate 232. The connecting plate 232 is equipped with a detachable plug-in rod 233 and is installed on the inner wall of the stretching table 211 through a sliding part. One end of the plug-in rod 233 is fixedly connected to a circular frame 234 that matches the trapezoidal block 222. The fixing component 240 includes a plug-in plate 241 plugged into the plug-in block 231, one side of the plug-in plate 241 extends to the outside of the stretching table 211, and is fixedly connected to a clamping part, and the sample is fixed in the clamping part.

[0021] Specifically, the driving unit 102 drives the synchronization component 210 to move and perform a tensile test on the sample fixed in the clamping part. The tensile test can be performed on multiple samples at the same time. When any sample breaks, the trapezoidal block 222 moves to one side of the circular frame 234 to control the plug-in block 231 to be away from the plug-in board 241, so that the clamping part fixing the broken sample can be separated from the stretching table 211, and the remaining samples can continue to be tensile tested. Finally, the moving distances of the two symmetrically arranged clamping parts are added together to determine the distance at which the tensile sample breaks and record it. This is not only simple to operate, but also greatly improves the efficiency of the tensile test on the sample.

[0022] Figure 5 and Figure 6As shown, the pushing assembly 220 includes a second pressing rod 221, which is movably sleeved in the inner ring of the stretching table 211 so that it can be pushed and pulled. One end of the second pressing rod 221 located inside the stretching table 211 is fixedly connected to a second trapezoidal block 222, and the inclined portion of the second trapezoidal block 222 fits the inner wall of the circular frame 234, so that when the second trapezoidal block 222 moves toward the circular frame 234, the circular frame 234 moves upward along the axial direction of the sliding portion through friction with the inclined portion, and the trapezoidal block Both sides of the second guide rod 222 are fixedly connected with a sliding sleeve 223, and the inner ring of the sliding sleeve 223 is movably sleeved with a guide rod 224. The two ends of the guide rod 224 are respectively fixedly connected to the inner walls of the two sides of the stretching platform 211, and one side of the sliding sleeve 223 is fixedly connected with an elastic part 225. The elastic part 225 adopts a spring, and the spring is sleeved on the outer ring of the guide rod 224 to prevent the spring from bending under force. The end of the elastic part 225 away from the sliding sleeve 223 is fixedly connected to the inner wall of the stretching platform 211.

[0023] Specifically, by pushing the pressing rod 221 toward the inside of the stretching table 211, the trapezoidal block 222 is driven to move toward one side of the circular frame 234. Since the inclined portion of the trapezoidal block 222 is in contact with the inner wall of the circular frame 234, the circular frame 234 moves upward along the axial direction of the sliding portion through friction with the inclined portion, thereby driving the plug-in block 231 to separate from the plug-in board 241. After releasing the pressing rod 221, the force of the elastic portion 225 pushes the trapezoidal block 222 and the pressing rod 221 back to their original positions.

[0024] like Figure 5 , Figure 6 and Figure 7 As shown, the sliding part includes a guide rod 3 237, which is movably sleeved in the inner ring of the connecting plate 232, and the two ends of the guide rod 3 237 are respectively fixedly connected to the inner walls of the two sides of the stretching table 211, so that the connecting plate 232 can only move along the axial direction of the guide rod 3 237. An elastic part 3 238 is fixedly connected to one side of the connecting plate 232. The elastic part 3 238 adopts a spring, and the spring is sleeved on the outer ring of the guide rod 3 237 to prevent the spring from bending under force. The end of the elastic part 3 238 away from the connecting plate 232 is fixedly connected to the inner wall of the stretching table 211, and the initial position of the plug-in block 231 is located above the plug-in plate 241 and plugged therein.

[0025] like Figure 5 , Figure 6 and Figure 7 As shown, the outer ring fixed sleeve of the plug-in rod 233 is provided with a baffle 235 , and the end of the plug-in rod 233 away from the circular frame 234 passes through the connecting plate 232 and is threadedly connected with a thread sleeve 236 . The connecting plate 232 is located between the baffle 235 and the thread sleeve 236 .

[0026] The thread sleeve 236 is connected to the plug-in rod 233 by threads, so that it is convenient to separate from the plug-in rod 233 . After the thread sleeve 236 is separated from the plug-in rod 233 , the plug-in rod 233 can be pulled out from the inner circle of the connecting plate 232 .

[0027] like Figure 2 , Figure 3 and Figure 4 As shown, the synchronization component 210 includes a pressing rod 212, one end of which is movably sleeved in the inner ring of the stretching table 211, and the other end of the inner ring of the pressing rod 212 is movably sleeved with a guide rod 213, and the side of the stretching table 211 away from the clamping portion is fixedly connected to the driving portion 102, the pressing rod 212 can move in the outer ring of the guide rod 213 and the inner ring of the stretching table 211, and the end of the guide rod 213 away from the pressing rod 212 is fixedly connected to the stretching table 211, and the interior of the pressing rod 212 is provided with an elastic part 214 fixedly connected to the guide rod 213, and the elastic part 214 adopts a spring, and the outer wall of the pressing rod 212 is fixedly connected with a trapezoidal block 215 that contacts the trapezoidal block 222, and the number of the trapezoidal blocks 215 is the same as the number of the trapezoidal blocks 222.

[0028] Specifically, when the pressing rod 1 212 is pushed to move it toward the inside of the stretching table 211, since the inclined portion of the trapezoidal block 1 215 is in conflict with the side wall of the trapezoidal block 222, the pressing rod 1 212 will push the trapezoidal block 222 toward the side close to the circular frame 234 while driving the trapezoidal block 1 215 to move toward the side of the trapezoidal block 222, so that the multiple plug-in blocks 231 move upward at the same time, and the multiple plug-in boards 241 can be inserted into the stretching table 211 at the same time. Inside, when the pressing rod 1 212 is released, the pressing rod 1 212 will drive the trapezoidal block 1 215 away from the trapezoidal block 2 222 through the force of the elastic part 1 214, and the trapezoidal block 222 will be away from the circular frame 234 through the force of the elastic part 225, and the plug-in block 231 will be plugged into the plug-in plate 241 through the force of the elastic part 3 238, so that multiple clamping parts can be connected to the stretching table 211 at the same time, which is not only simple to operate, but also convenient for fixing and stretching multiple samples.

[0029] Example 2 like Figure 2 , Figure 4 and Figure 5As shown, the tensile specimen gauge length marking device, compared with the first embodiment, the clamping portion of this embodiment includes a clamping seat 244 fixedly connected to the plug-in plate 241, the top of the clamping seat 244 is fixedly connected to a fixing frame 245, the fixing frame 245 is threadedly connected to a screw rod 246 on a side away from the clamping seat 244, the screw rod 246 is rotatably connected to an upper clamping plate 247 at one end close to the clamping seat 244, the outer wall of the upper clamping plate 247 is fixedly connected to a guide rod 248, and the guide rod 248 is at a side away from the upper clamping plate 247. The end passes through the fixed frame 245, and the guide rod 248 and the screw rod 246 are located on the same side. The guide rod 248 prevents the upper clamping plate 247 from rotating together with the screw rod 246. The inner walls of the clamping seat 244 and the upper clamping plate 247 are provided with multiple rubber protrusions 249. The sample is set between the clamping seat 244 and the upper clamping plate 247. The friction with the sample is increased by the rubber protrusions 249. The bottom of the plug-in board 241 is fixedly connected with a moving block 242, and the moving block 242 is slidably connected to the supporting platform 101.

[0030] Specifically, the screw rod 246 is rotated to drive the upper clamping plate 247 away from the clamping seat 244. Through the cooperation of the guide rod 248 and the fixing frame 245, the upper clamping plate 247 cannot rotate along with the screw rod 246. After the upper clamping plate 247 moves to the farthest distance, the sample is placed on the clamping seat 244, and then the screw rod 246 is rotated in the opposite direction to drive the upper clamping plate 247 to move closer to the clamping seat 244 until the sample is firmly fixed.

[0031] The stretching method of the tensile specimen gauge marking device comprises the following steps: S10. Sample marking Select multiple samples of the same material for marking, using two or more marking methods; S20, tensile test Fixing a plurality of samples on the stretching mechanism 200 for stretching test; S30. Collect data Collect the data of tensile strength of each specimen, as shown in the table below, and test whether the data conforms to normal distribution; Statistics of actual measurement results of gauge length using different marking methods S40, Model Building A normal distribution model is established based on the tensile strength data of multiple samples, and its function is: ƒ Among them, x is the variable, μ is the mean, and σ is the standard deviation; S50, result output The optimal labeling method was determined based on the S40 normal distribution model.

[0032] S10. In sample marking, the marking method adopts laser method, punching method and other methods.

[0033] S10. The gauge length mark in the specimen marking is used to calculate the elongation after fracture. The calculation formula for the elongation after fracture is A% = (L U -L0) / L0×100%,L U is the gauge length after breaking, and L0 is the original gauge length.

[0034] Among them, the original gauge length L0=25mm, and the sample marking deviation L0=25mm±0.25mm.

[0035] S20, during the stretching test: S21, fixing the specimens, fixing the plurality of specimens between the two stretching tables 211 by means of a plurality of symmetrically arranged clamping parts; S22, stretching the sample, starting the two driving parts 102 at the same time to drive the two stretching platforms 211 to move away from each other, and performing a stretching test on the multiple samples located in the middle at the same time; S23, sample fracture. When any sample fractures, the driving unit 102 is turned off, and the corresponding pressing rod 221 is pushed to move the trapezoidal block 222 to the side close to the circular frame 234. The plug-in block 231 can be driven away from the plug-in board 241 through the friction between the hypotenuse of the trapezoidal block 222 and the circular frame 234. When the plug-in block 231 is completely separated from the plug-in board 241, the clamping part fixing the fractured sample will be separated from the stretching table 211. The driving unit 102 is started again to continue the stretching test of the remaining samples. The moving distances of the two symmetrically arranged clamping parts are added together to determine the distance at which the tensile sample fractures, and the distance is recorded. S30. During data collection, multiple comparisons were performed to further determine whether there was a difference between the two groups’ means. S30. During the data collection, the normal distribution of the two samples with different labeling methods was compared by Levene's test to check whether the variances were the same.

[0036] S30. When collecting data, the deviation of data from two groups using different methods is compared by F test to determine whether there is a significant difference in precision.

[0037] like Fig. 9 As shown in the table above, from the statistical analysis point of view: ① Equal variance test P=0.145>0.05, indicating that the statistical analysis of the test results of the two marking methods has no statistically significant difference in variance, that is, both methods can be used, but it can be seen from the graph that the data of the punch method is more dispersed than the data of the laser method.

[0038] The marking of the gauge length is used to calculate the elongation after fracture. The calculation formula for the elongation after fracture is A%=(LU-L0) / L0×100%, where LU is the gauge length after fracture and L0 is the original gauge length. For the original gauge length, L0=25mm is the same. When marking the original gauge length, a punch is used to make dots and the nominal size is calculated. The human factor has a greater impact, the data will appear scattered, and the consistency of the test results is poor. If laser marking is used, the test results will be concentrated and stable, with a small error and good consistency.

[0039] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit them.

Claims

1. A tensile specimen gauge marking device, characterized in that: include: A carrying mechanism (100), the carrying mechanism (100) comprising two symmetrically arranged driving parts (102); Two symmetrically arranged stretching mechanisms (200), the stretching mechanisms (200) comprising a synchronization component (210) fixedly connected to a driving portion (102), a plurality of pushing components (220) and a connecting component (230) being installed inside the synchronization component (210), and the synchronization component (210) comprising a stretching platform (211), the connecting component (230) being installed with a detachable fixing component (240), and the fixing component (240) fixingly clamping and holding a sample; The connection assembly (230) comprises a plug-in block (231), the outer wall of the plug-in block (231) is fixedly connected to a connection plate (232), the connection plate (232) is installed with a detachable plug-in rod (233) and is installed on the inner wall of the stretching table (211) through a sliding part, and one end of the plug-in rod (233) is fixedly connected to a circular frame (234) that matches the second trapezoidal block (222); The fixing assembly (240) comprises a plug-in board (241) plugged into the plug-in block (231), one side of the plug-in board (241) extends to the outside of the stretching table (211) and is fixedly connected to a clamping portion, in which the sample is fixed; The driving part (102) drives the synchronous assembly (210) to move and perform a tensile test on a sample fixed in the clamping part. When the sample breaks, the second trapezoidal block (222) moves toward one side of the circular frame (234) to control the plug-in block (231) to be away from the plug-in board (241), so that the broken sample is retained at the position where the break occurs.

2. The tensile specimen gauge marking device according to claim 1, characterized in that: The pushing component (220) comprises: A second pressing rod (221), wherein the second pressing rod (221) is movably sleeved in the inner ring of the stretching platform (211), and one end of the second pressing rod (221) located inside the stretching platform (211) is fixedly connected to a second trapezoidal block (222), the inclined portion of the second trapezoidal block (222) is in contact with the inner wall of the circular frame (234), and both sides of the second trapezoidal block (222) are fixedly connected to a sliding sleeve (223), and the inner ring movably sleeve of the sliding sleeve (223) is provided with a second guide rod (224), and the two ends of the second guide rod (224) are respectively fixedly connected to the inner walls of the two sides of the stretching platform (211), and one side of the sliding sleeve (223) is fixedly connected to a second elastic part (225), and the end of the second elastic part (225) away from the sliding sleeve (223) is fixedly connected to the inner wall of the stretching platform (211).

3. The tensile specimen gauge marking device according to claim 2, characterized in that the sliding portion include: A guide rod three (237), wherein the guide rod three (237) is movably sleeved in the inner ring of the connecting plate (232), and the two ends of the guide rod three (237) are respectively fixedly connected to the inner walls of the two sides of the stretching platform (211), one side of the connecting plate (232) is fixedly connected to an elastic part three (238), and one end of the elastic part three (238) away from the connecting plate (232) is fixedly connected to the inner wall of the stretching platform (211), and the outer ring of the plug-in rod (233) is fixedly sleeved with a baffle (235), and one end of the plug-in rod (233) away from the circular frame (234) passes through the connecting plate (232) and is threadedly connected to a threaded sleeve (236), and the connecting plate (232) is located between the baffle (235) and the threaded sleeve (236).

4. The tensile specimen gauge marking device according to claim 3, characterized in that: The synchronization component (210) includes: A pressing rod (212), one end of which is movably sleeved in the inner ring of the stretching platform (211), and the other end of which is movably sleeved in the inner ring of the pressing rod (212) is provided with a guide rod (213); a side of the stretching platform (211) away from the clamping portion is fixedly connected to the driving portion (102); an end of the guide rod (213) away from the pressing rod (212) is fixedly connected to the stretching platform (211); an elastic portion (214) fixedly connected to the guide rod (213) is provided inside the pressing rod (212); and a trapezoidal block (215) abutting against the trapezoidal block (222) is fixedly connected to the outer wall of the pressing rod (212).

5. The stretching method according to any one of claims 1 to 4, characterized in that: The following steps are included: S10. Sample marking Select multiple samples of the same material for marking, using two or more marking methods; S20, tensile test Fixing a plurality of specimens on a tensile mechanism (200) to perform a tensile test; S30. Collect data Collect the tensile strength data of each specimen and test whether the data conforms to the normal distribution; S40, Model Building A normal distribution model is established based on the tensile strength data of multiple samples, and its function is: ƒ Among them, x is the variable, μ is the mean, and σ is the standard deviation; S50, result output The optimal labeling method was determined based on the S40 normal distribution model.

6. The tensile specimen gauge marking method according to claim 5, characterized in that: S10. In sample marking, the marking method adopts laser method, punching method and other methods.

7. The tensile specimen gauge marking method according to claim 5, characterized in that: S10. The gauge length mark in the specimen marking is used to calculate the elongation after fracture. The calculation formula for the elongation after fracture is A% = (L U -L0) / L0×100%,L U is the gauge length after fracture, L0 is the original gauge length, the original gauge length L0=25mm, and the specimen marking deviation L0=25mm±0.25mm.

8. The method for marking the gauge length of a tensile specimen according to claim 5, characterized in that: S20, during the tensile test: S21, fixing the specimens, fixing the plurality of specimens between two tensile stages (211) by means of a plurality of symmetrically arranged clamping parts; S22, stretching the sample, simultaneously starting the two driving parts (102) to drive the two stretching platforms (211) to move away from each other, and simultaneously performing a stretching test on a plurality of samples located in the middle; S23, the sample breaks. When any sample breaks, the driving unit (102) is turned off, and the corresponding pressing rod 2 (221) is pushed to move the trapezoidal block 2 (222) to the side close to the circular frame (234). The plug-in block (231) can be driven away from the plug-in board (241) through the friction between the hypotenuse of the trapezoidal block 2 (222) and the circular frame (234). When the plug-in block (231) is completely separated from the plug-in board (241), the clamping part fixing the broken sample will be separated from the stretching table (211), and the driving unit (102) is started again to continue the stretching test of the remaining samples. The moving distances of the two symmetrically arranged clamping parts are added together to determine the distance at which the tensile sample breaks, and the distance is recorded.

9. The tensile specimen gauge marking method according to claim 5, characterized in that: S30. In the data collection, multiple comparisons were performed to further determine whether there was a difference between the means of the two groups. The normal distribution of the two samples with different labeling methods was compared by Levene's test to test whether the variances were the same.

10. The tensile specimen gauge marking method according to claim 5, characterized in that: S30. When collecting data, the deviation of data from two groups using different methods is compared by F test to determine whether there is a significant difference in precision.

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