A deformed steel bar tensile measurement system and a deformed steel bar tensile measurement method

Abstract

A ribbed steel bar tensile measurement system and a ribbed steel bar tensile measurement method belong to the technical field of tensile tests. A ribbed steel bar tensile measurement system includes: a tensile testing machine, including a No. 1 tensile testing machine and a No. 2 tensile testing machine, which are used for measuring the tensile process of ribbed steel bar tensile specimens. The No. 1 tensile testing machine and the No. 2 tensile testing machine are arranged adjacent to each other; a manipulator, which is used for clamping the ribbed steel bar tensile specimen and taking and sending it to the tensile testing machine; a specimen rack, including two No. 1 specimen racks and two No. 2 specimen racks. The two No. 2 specimen racks are arranged adjacent to each other, and the two No. 2 specimen racks are respectively arranged opposite to the No. 1 tensile testing machine and the No. 2 tensile testing machine; the two No. 1 specimen racks are arranged obliquely with respect to the center line of the manipulator. It has the advantages of high detection efficiency, simple production of detection specimens, reasonable system layout, and can realize multi-functional detection, etc.

Description

Technical Field

[0001] The present invention belongs to the technical field of tensile testing, and in particular relates to a tensile measurement system for ribbed steel and a method for measuring the tensile strength of ribbed steel. Background Art

[0002] In the prior art, to measure the elongation after fracture A and the total elongation at maximum force A gt of ribbed steel, equally spaced marks need to be made on the parallel length of the specimen. According to the diameter of the steel bar product, the distance between the equally spaced gauge lengths is 5 mm, 10 mm, or 20 mm.

[0003] After the tensile test, after the tensile test is completed, a vernier caliper needs to be used to measure the gauge length after fracture to calculate the elongation after fracture A and a manual measurement method is used to obtain the total elongation at maximum force A gt . There are measurement errors both in marking the gauge length and in measuring the gauge length points after fracture.

[0004] The total elongation at maximum force A gt In the tensile standard GB / T228.1, the total elongation at maximum force is measured on the force-elongation curve obtained by an extensometer. The total elongation at maximum force A gt . That is:[[]]

[0005] A gt = ΔL m / L e × 100

[0006] There is no hardware in the laboratory to directly measure A gt , and the manual measurement method used has a large measurement error.

[0007] The calculation formula for elongation: the percentage of the elongation of the gauge length to the original gauge length, that is:[[]]

[0008] A = (L u - L o ) / L o × 100

[0009] Where: L o is the original gauge length of the specimen; L u is the gauge length after fracture of the specimen, in mm.

[0010] When measuring the elongation after fracture A and the total elongation at maximum force A of ribbed steel using a vernier caliper gt , the original gauge length of A is calculated according to the steel bar specification and is 5d (5 times the gauge diameter), and the gauge length of the manual method for A gt is 100 mm. In reality, the distance between the equally spaced gauge lengths marked must be a common divisor of the original gauge length of A and 100.

[0011] During manual measurement

[0012] A gt = A g+ R m / 2000

[0013] In the formula: A g is the maximum force F m plastic elongation. A g It shall be measured with a gauge length of 100 mm, at least 50 mm or 2d (whichever is larger) from the fracture. If the distance between the grip and the gauge length is less than 20 mm or d (whichever is larger), the test shall be regarded as invalid.

[0014] A gt Manual measurement is required to ensure that one of the segments of the specimen after fracture meets the measurement length. The larger the specification, the longer the tensile specimen length of the deformed steel bar. This results in inconsistent specimen lengths for deformed steel bars of different specifications. As can be seen from the above, the existing tensile test equipment cannot simultaneously obtain the maximum force total elongation A gt and the elongation after fracture A; and when measuring different specimens, different specimen lengths need to be used, which brings many inconveniences to the sample preparation work, is not conducive to rapid large-scale specimen detection, and cannot meet the existing production detection requirements.

[0015] Existing technical solution 1: A virtual optical extensometer and its measurement method disclose a virtual optical extensometer and its measurement method. The virtual optical extensometer includes an image acquisition module and a computer. The computer is provided with an image processing module, a data processing module, and a result output module. The image acquisition module is connected to the computer. The image acquisition module transmits the acquired original image to the computer. The image processing module extracts the marker point image from the original image. The data processing module calculates based on the extracted marker point image and outputs the result through the result output module. The virtual extensometer of the present invention is easy to install and does not occupy any space; the range is not limited, and the extensometer will not be damaged due to changes in the measurement range; it is a non-contact measurement and has no additional influence on the measured object; at the same time, the measurement method of the virtual optical extensometer of the present invention has advantages such as good linearity, high measurement accuracy, and no cumulative error. However, this system does not give the specific settings of the system for simultaneously and efficiently detecting a large number of specimens, and although it gives the setting of marker points, it does not give an effective and rapid detection method for marking deformed steel bars and processing specimens of different diameters, and cannot simultaneously obtain the maximum force total elongation A gt and the elongation after fracture A.

[0016] Based on the above existing problems, the specimen detection method for deformed steel bars needs to be improved urgently, such as low detection efficiency, complex production of detection specimens, unreasonable system layout, and inability to achieve multi-functional detection. Summary of the Invention

[0017] The purpose of the embodiments of the present application is to provide a ribbed steel tensile measurement system and a ribbed steel tensile measurement method, which have high detection efficiency, simple production of detection specimens, reasonable system layout, and can achieve multi-functional detection.

[0018] The present application is implemented as follows:

[0019] In a first aspect, an example of the present application provides a ribbed steel tensile measurement system, including:

[0020] A tensile testing machine, including a No. 1 tensile testing machine and a No. 2 tensile testing machine, for measuring the tensile process of ribbed steel tensile specimens, and the No. 1 tensile testing machine and the No. 2 tensile testing machine are arranged adjacent to each other;

[0021] A manipulator, for clamping the ribbed steel tensile specimen and transporting it to the tensile testing machine;

[0022] A specimen rack, including two No. 1 specimen racks and two No. 2 specimen racks, the two No. 2 specimen racks are arranged adjacent to each other, and the two No. 2 specimen racks are respectively arranged opposite to the No. 1 tensile testing machine and the No. 2 tensile testing machine; the two No. 1 specimen racks are arranged obliquely with respect to the center line of the manipulator.

[0023] In some examples, the two No. 1 specimen racks being arranged obliquely with respect to the center line of the manipulator specifically means that the included angle α between the center line of the No. 1 specimen rack and the center line of the manipulator is 27° to 33°.

[0024] In some examples, the No. 1 specimen rack and the No. 2 specimen rack include a vertical column, a cross bar, a tilting bar, a stabilizing bar and a base, wherein the vertical column is connected to the base; the tilting bar is arranged obliquely with respect to the vertical column, one end is connected to the vertical column, and the other end is a free end; the free end of the tilting bar is perpendicularly connected to the stabilizing bar; the stabilizing bar is used to support the ribbed steel tensile specimen; the cross bar is fixedly connected to the left and right vertical columns.

[0025] In some examples, the tilting bar being arranged obliquely with respect to the vertical column specifically means that the included angle β between the tilting bar and the horizontal direction is 10° to 25°.

[0026] In some examples, at least three concave grooves are provided on the stabilizing bar for placing the ribbed steel tensile specimen.

[0027] In some examples, the No. 1 specimen rack is provided with 12 rows of the tilting bars, and the No. 2 specimen rack is provided with 9 rows of the tilting bars.

[0028] In some examples, the column spacing D1 of the No. 1 specimen rack: the tilting bar spacing D2 is 2.8:1 to 3:1.

[0029] In some examples, the column spacing D3 of the 2# specimen holder and the tilt rod spacing D4 are in a ratio of 1.5:1 to 1.7:1.

[0030] In a second aspect, an example of the present application provides a method for measuring the tensile strength of deformed steel bars, using the above-mentioned deformed steel bar tensile measurement system, including the following steps:

[0031] Step 1: Place the deformed steel bar tensile specimen on the specimen holder at an angle of 45° between the longitudinal ribs of the deformed steel bar tensile specimen and the plane where the center line of the deformed steel bar tensile specimen is located and the horizontal plane. The deformed steel bar specimen with a diameter specification of 12 mm to 31 mm is placed on the 1# specimen holder, and the deformed steel bar specimen with a diameter specification of 32 mm to 40 mm is placed on the 2# specimen holder;

[0032] Step 2: The manipulator automatically picks up deformed steel bar tensile specimens of different specifications and sends them to the tensile testing machine for clamping;

[0033] Step 3: Adjust the video extensometer camera of the tensile testing machine to face the transverse ribs of the clamped deformed steel bar tensile specimen; measure the deformed steel bar tensile specimen in a non-contact manner to obtain tensile deformation data; the video extensometer identifies the transverse ribs on the surface of the deformed steel bar tensile specimen as marking points, and synchronously measures and tracks the local strains of 10 marking points; the sampling frequency of the video extensometer is 500 pfs / Hz;

[0034] Step 4: The tensile test starts. The video extensometer is controlled by the control system in the control room. The test rate is controlled by the strain rate according to GB / T228.1. The local strains of 10 marking points are tracked in real time, the local strain maximum point is calculated and marked, and the tracking is continued until the specimen breaks;

[0035] Step 5: Obtain a force-extension curve, and obtain the maximum force F m and the total extension A of the maximum force gt , and after the specimen breaks, measure the elongation after fracture A.

[0036] In some examples, during the clamping process of the deformed steel bar tensile specimen, the size of the identification points of the video extensometer is adjusted according to the diameter specification of the specimen:

[0037] For a diameter specification of 12 mm to 20 mm, the identification point size is 90 dpi * 70 dpi;

[0038] For a diameter specification of 21 mm to 30 mm, the identification point size is 90 dpi * 80 dpi;

[0039] For a diameter specification of 31 mm to 40 mm, the identification point size is 128 dpi * 80 dpi.

[0040] The beneficial effects of the present application include:

[0041] The center of the manipulator is set, two tensile testing machines and four specimen holders are arranged oppositely, and two No. 1 specimen holders are arranged obliquely with respect to the center line of the manipulator. The reasonable layout of the above system components can enhance the coherence of sample feeding, sampling and testing in the tensile test, greatly improve the detection efficiency of a large number of specimens, and simultaneously obtain the maximum force F m , the total elongation A at the maximum force gt , and the elongation after fracture A. Further, the angle of the No. 1 specimen holder arranged obliquely with respect to the center line of the manipulator is optimized, and the equipment layout is more compact, which can further improve the detection efficiency of a large number of specimens. Further, the tilting rod of the specimen holder is arranged obliquely with respect to the column, and at least three concave grooves are arranged on the stabilizing rod for the longitudinal ribs of the deformed steel bar tensile specimen to be placed on the specimen holder at an angle of 45° to the horizontal plane. The contact area between the deformed steel bar tensile specimen and the specimen holder is small, and it can be stably supported. When the manipulator grabs and places it on the tensile testing machine, the deflection degree of the deformed steel bar tensile specimen is the smallest, and all transverse ribs are almost in the same alignment position for the tensile testing machine, which can ensure the accuracy and consistency of the detection results during the automatic tensile test. Further, the column spacing and tilting rod spacing of different specimen holders are selected within a suitable range, and different heights are set, which can stably support tensile specimens with different diameter ranges, and the specimen flipping degree is the smallest, improving the accuracy and consistency of the detection results during the automatic tensile test. Further, the size of the video extensometer recognition point is adjusted according to the specimen diameter specification, and through reasonable setting of the recognition point size, the accuracy and consistency of the detection results of different specimens are achieved. Description of the Drawings

[0042] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present application, and therefore should not be regarded as limiting the scope. For those of ordinary skill in the art, without creative efforts, other related drawings can also be obtained based on these drawings.

[0043] Figure 1 Layout diagram of the deformed steel bar tensile measurement system;

[0044] Figure 2 Stereogram of specimen holder 1;

[0045] Figure 3 Front view of specimen holder 1;

[0046] Figure 4 Front view of specimen holder 2;

[0047] Figure 5 Tensile diagram of the deformed steel bar specimen;

[0048] Figure 6 Cross-sectional view of the deformed steel bar specimen.

[0049] Icons: 1-1# Tensile testing machine; 2-1# Tensile testing machine; 3-Manipulator; 4-1# Specimen holder; 5-2# Specimen holder; 6-Control room; 7-Enclosed protective fence; 8-Included angle α; 9-Column; 10-Cross bar; 11-Tilting bar; 12-Stabilizing bar; 13-Base; 14-Inclination angle β; 15-Transverse rib; 16-Ribbed steel tensile specimen; 17-Longitudinal rib; 18-Center line; 19-Plane where the longitudinal rib and the center line are located; 20-Horizontal plane; 21-Inclination angle γ; D1-Spacing 1; D2-Spacing 2; D3-Spacing 3; D4-Spacing 4. Specific embodiments

[0050] For the convenience of understanding the working principle and usage method of the ribbed steel tensile measurement system, the structure of the ribbed steel tensile measurement system is given below, and based on it, the usage method of the ribbed steel tensile measurement system in this application is described.

[0051] The structure of the ribbed steel tensile measurement system is referred to Figure 1-4 as shown.

[0052] A ribbed steel tensile measurement system includes:

[0053] Tensile testing machines, including 1# tensile testing machine 1 and 2# tensile testing machine 2, which are used for measuring the tensile process of ribbed steel tensile specimens. 1# tensile testing machine 1 and 2# tensile testing machine 2 are arranged adjacent to each other (see Figure 1 ), 1# tensile testing machine 1 is horizontally arranged, and 2# tensile testing machine is vertically arranged. The model of the tensile testing machine is not specifically limited. For example, it can be a device with the following functions: a microcomputer-controlled electro-hydraulic servo testing machine integrates electro-hydraulic servo automatic control, automatic measurement, data acquisition, screen display, and test result processing. Based on the oil cylinder lower-mounted host platform, it is equipped with a precision oil pump and an electro-hydraulic servo valve, a PC servo controller, to achieve multi-channel closed-loop control, and complete the full-automatic control and automatic measurement of the test process. It can use an optical encoder for displacement measurement. The controller adopts an embedded single-chip microcomputer structure, with a powerful measurement and control software built-in, integrating measurement, control, calculation, and storage functions. It has functions such as automatically calculating stress, automatically counting results; automatically recording the force values or elongation amounts at the maximum point, fracture point, and specified points; using a computer to dynamically display the test process and test curves, and perform data processing. After the test, the curve can be magnified through the graphics processing module for data re-analysis and editing, and reports can be printed, etc.

[0054] The testing machine consists of a mainframe, a video extensometer, a camera, an electrical control box, measuring, displaying, and recording devices, etc. The main function of the mainframe is to apply force to the specimen. The tensile testing machine is provided with a tensile specimen clamping device for clamping the tensile specimen transported by the manipulator 3. During use, the camera of the video extensometer tracks and marks the transverse ribs of the threaded steel tensile specimen being clamped.

[0055] The manipulator 3 is used to clamp the threaded steel tensile specimen 16 and pick it up and send it to the tensile testing machine. The model of the manipulator 3 is not specifically limited. According to the driving method, it can be hydraulic, pneumatic, electric, or mechanical. The manipulator mainly consists of three major parts: an execution mechanism, a driving mechanism, and a control system. The hand is the part used to grasp the specimen and is of the clamping type. Through the motion mechanism, the hand completes various rotations (swings), movements, or compound movements to achieve the specified actions, such as rotating the specimen from the horizontal direction on the specimen rack to the vertical direction as required. The control system is connected to the computer in the control room 6 to realize the control of the manipulator 3.

[0056] The specimen rack includes two No. 1 specimen racks 4 and two No. 2 specimen racks 5. The two No. 2 specimen racks 5 are arranged adjacent to each other, and the two No. 2 specimen racks 5 are respectively arranged opposite to the No. 1 tensile testing machine 1 and the No. 2 tensile testing machine 2; the two No. 1 specimen racks 4 are arranged obliquely with respect to the center line of the manipulator 3. The included angle α8 between the center line of the No. 1 specimen rack 4 and the center line of the manipulator 3 is 27° to 33°, and can be selected as 27°, 28°, 29°, 30°, 31°, 32°, 33°, etc. See Figure 1 .

[0057] Set at the center of the manipulator, two tensile testing machines and four specimen racks are arranged opposite to each other. The two No. 1 specimen racks are arranged obliquely with respect to the center line of the manipulator. The above system components are reasonably arranged and set within the enclosed protective fence 7, which can enhance the coherence of specimen feeding, sampling, and testing in the tensile test, greatly improve the detection efficiency of a large number of specimens, and at the same time, the maximum force F m , the total elongation at maximum force A gt , and the elongation after fracture A can be obtained simultaneously. The angle of the No. 1 specimen rack arranged obliquely with respect to the center line of the manipulator is optimized, and the equipment layout is more compact, which can further improve the detection efficiency of a large number of specimens.

[0058] In some examples, the 1# specimen holder 4 and the 2# specimen holder 5 include a vertical column 9, a cross bar 10, a tilting bar 11, a stabilizing bar 12 and a base 13. The vertical column 9 is connected to the base 13 by a fixed connection such as welding or bolt connection. According to specific usage requirements, the vertical column 9 can have different implementation forms. For example, the vertical column 9 can be in a columnar structure, a plate-like structure or other implementation forms, and the cross-sectional shape of the rod body of the vertical column 9 can be circular, rectangular, oval or other shapes. The tilting bar 11 is arranged obliquely with respect to the vertical column 9, one end is connected to the vertical column 9 by a fixed connection such as welding or bolt connection, and the other end is a free end. According to specific usage requirements, the tilting bar 11 can have different implementation forms. For example, the tilting bar 11 can be in a rod-like structure, a plate-like structure or other implementation forms, and the cross-sectional shape of the rod body of the tilting bar 11 can be circular, rectangular, oval or other shapes.

[0059] The free end of the tilting bar 11 is perpendicularly connected to the stabilizing bar 12 by a fixed connection such as welding or bolt connection. The stabilizing bar 12 is used to support the deformed steel bar tensile specimen 16. According to specific usage requirements, the stabilizing bar 12 can have different implementation forms. For example, the stabilizing bar 12 can be in a rod-like structure, a plate-like structure or other implementation forms, and the cross-sectional shape of the rod body of the stabilizing bar 12 can be circular, rectangular, oval or other shapes. At least three concave grooves are provided on the stabilizing bar 12 for placing the deformed steel bar tensile specimen 16. The concave grooves can be semi-circular, semi-elliptical, V-shaped or other grooves, and preferably V-shaped grooves. The longitudinal rib 17 of the deformed steel bar tensile specimen 16 and the plane 19 where the center line 18 is located are placed on the specimen holder at an angle of 45° with the horizontal plane 20. The contact area between the deformed steel bar tensile specimen 16 and the specimen holder is small, and it can be stably supported. When the manipulator grabs and places it on the tensile testing machine, the degree of deflection of the deformed steel bar tensile specimen 16 is the smallest, and all the transverse ribs are almost in the same alignment position with respect to the tensile testing machine, which can ensure the accuracy and consistency of the test results during the automatic tensile test. When the manipulator grabs and places the deformed steel bar tensile specimen 16 on the tensile testing machine, the deflection of the deformed steel bar tensile specimen 16 means that when grabbing and placing, since the deformed steel bar specimen is circular, inevitable rotation occurs when it first comes into contact.

[0060] The cross bar 10 is fixedly connected to the left and right vertical columns 9 by a fixed connection such as welding or bolt connection. According to specific usage requirements, the cross bar 10 can have different implementation forms. For example, the cross bar 10 can be in a rod-like structure, a plate-like structure or other implementation forms, and the cross-sectional shape of the rod body of the cross bar 10 can be circular, rectangular, oval or other shapes.

[0061] In some examples, the tilting bar 11 being arranged obliquely with respect to the vertical column 9 specifically means that the inclination angle β of the tilting bar 11 with respect to the horizontal direction is 10° to 25°, and can be selected as 10°, 13°, 16°, 18°, 21°, 23°, 25°, etc.

[0062] In some examples, the No. 1 specimen rack 4 near the tensile testing machine is provided with 12 rows of tilting rods 11, and the No. 2 specimen rack 5 far from the tensile testing machine is provided with 9 rows of tilting rods 11. The column spacing D1 of the No. 1 specimen rack 4: the tilting rod spacing D2 is 2.8:1 to 3:1, and can be selected as 2.8:1, 2.9:1, 3:1, etc. The column spacing D3 of the No. 2 specimen rack 5: the tilting rod spacing D4 is 1.5:1 to 1.7:1, and can be selected as 1.5:1, 1.6:1, 1.7:1, etc. The deformed steel bar specimens with a diameter specification of 12 mm to 31 mm are placed on the No. 1 specimen rack 4, and the deformed steel bar specimens with a diameter specification of 32 mm to 40 mm are placed on the No. 2 specimen rack 5.

[0063] The height of the specimen rack near the tensile testing machine is higher than that of the specimen rack far from the tensile testing machine, which is used to place the deformed steel bar specimens with a smaller diameter specification. By adopting a higher column spacing: tilting rod spacing ratio, the tensile specimens with different diameter ranges can be stably supported, and the degree of specimen flipping is minimized, improving the accuracy and consistency of the test results during the automatic tensile test.

[0064] In a second aspect, an example of the present application provides a method for measuring the tensile strength of deformed steel bars, using the above-mentioned deformed steel bar tensile measurement system, including the following steps:

[0065] Step 1, the deformed steel bar tensile specimen 16 is placed on the specimen rack at an angle of 45° with respect to the angle γ between the longitudinal rib 19 of the deformed steel bar tensile specimen 16 and the plane 19 where the center line 18 of the deformed steel bar tensile specimen is located and the horizontal plane 20. The deformed steel bar specimens with a diameter specification of 12 mm to 31 mm are placed on the No. 1 specimen rack 4, and the deformed steel bar specimens with a diameter specification of 32 mm to 40 mm are placed on the No. 2 specimen rack 5. The length of the tensile specimen is uniformly 630 ± 5 mm.

[0066] When the deformed steel bar tensile specimen 16 is placed on the specimen rack, the specimen is parallel to the horizontal plane. Among them, the circular cross-section of the deformed steel bar tensile specimen 16 is perpendicular to the center line 18, and there is a longitudinal rib 17 parallel to the center line 18 on the surface of the deformed steel bar tensile specimen 16. The plane where they are located is the plane 19 where the longitudinal rib 19 of the deformed steel bar tensile specimen 16 and the center line 18 of the deformed steel bar tensile specimen are located; when the specimen is parallel to the horizontal plane, a horizontal plane 20 passing through the center line 18 forms an angle of inclination γ with the plane 19. The optimal angle of inclination is 45°, so as to ensure that the transverse ribs 15 of the deformed steel bar tensile specimen 16 are presented in the display system to the greatest extent during tensile testing.

[0067] Step 2, the manipulator 3 automatically picks up the deformed steel bar tensile specimens 16 of different specifications and sends them to the tensile testing machine for clamping;

[0068] Step 3: Adjust the video extensometer camera of the tensile testing machine to face the transverse ribs 15 of the threaded steel tensile specimen 16 being clamped; measure the tensile deformation data of the threaded steel tensile specimen in a non-contact manner; the video extensometer identifies the transverse ribs 15 on the surface of the threaded steel tensile specimen as marking points and synchronously measures and tracks the local strains of 10 marking points; the sampling frequency of the video extensometer is 500 pfs / Hz; the video extensometer is fixed behind the tensile testing machine and consists of an array of 6 high-definition USB 3.0 cameras. Using the centering assistance setting, the cameras are installed in a straight line with the load axis, automatically identifying the special points of the transverse ribs on the surface of the threaded steel sample as marks, without the need for additional marking points, and can synchronously measure and track at least 15 local strains.

[0069] During the clamping process of the threaded steel tensile specimen 16, adjust the size of the identification points of the video extensometer according to the specimen diameter specification:

[0070] For a diameter specification of 12 mm to 20 mm, the identification point size is 90 dpi * 70 dpi;

[0071] For a diameter specification of 21 mm to 30 mm, the identification point size is 90 dpi * 80 dpi;

[0072] For a diameter specification of 31 mm to 40 mm, the identification point size is 128 dpi * 80 dpi.

[0073] Specimens of different diameter specifications use the same length. By adjusting the size of the identification points of the video extensometer according to the specimen diameter specification and reasonably setting the size of the identification points, the accuracy and consistency of the test results for different specimens are achieved, avoiding the complex process of preparing specimens of different lengths, which is conducive to further shortening the test time and improving the test efficiency.

[0074] Step 4: Before the test starts, turn on the light source of the video extensometer so that the image of the threaded steel specimen clearly appears on the computer software in the control room 6. In the software, the red line and the yellow line in the video image form a measurement axis, and the position of this axis should always be consistent with the specimen axis. When the tensile test starts, the video extensometer is controlled by the control system in the control room 6, and the test rate is controlled using the strain rate in GB / T228.1, and the local strains of 10 marking points are tracked in real time (10 identification points are the optimal solution. The 10 identification points ensure accurate data collection. The identification points at both ends are moved to the clamping surface by mouse to ensure that the parallel length range of the specimen is monitored by the video and covers the entire field of view.), calculate the local strain of each point to obtain the point with the maximum local strain for identification (it will be identified in green in the automatic control system), and track until the specimen breaks;

[0075] Step 5: Obtain the force-extension curve graph, and obtain the maximum force F m and the total extension A of the maximum force gt, after the specimen fractures, the elongation after fracture A is measured.

[0076] Through the above-mentioned tensile measurement system for ribbed steel bars, the automatic measurement of tensile specimens of ribbed steel bars can be realized, enhancing the coherence of sample delivery, sampling, and testing in the tensile test, greatly improving the detection efficiency of a large number of specimens, and simultaneously obtaining the maximum force F m , the total elongation at maximum force A gt , and the elongation after fracture A. The contact area between the ribbed steel bar tensile specimen and the specimen holder is small, and it can stably support. When the manipulator grabs and places it on the tensile testing machine, the deflection degree of the ribbed steel bar tensile specimen is minimized, and all transverse ribs are almost in the same alignment position for the tensile testing machine, ensuring the accuracy and consistency of the detection results during the automatic tensile test.

[0077] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the above content is combined with the accompanying drawings in the embodiments of this application to clearly and completely describe the technical solutions in the embodiments of this application. Obviously, the described embodiments are part of the embodiments of this application, rather than all of them. Usually, the components of the embodiments of this application described and illustrated in the accompanying drawings here can be arranged and designed in various different configurations. Therefore, the detailed description of the embodiments of this application provided in the accompanying drawings above is not intended to limit the scope of the claimed application, but merely represents the selected embodiments of this application. Based on the embodiments in this application, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of this application.

[0078] It should be noted that similar reference numerals and letters indicate similar items in the following drawings. Therefore, once an item is defined in one drawing, it does not need to be further defined and explained in subsequent drawings.

[0079] In the description of this application, it should be noted that the orientation or positional relationship indicated by the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings, or the orientation or positional relationship in which the products of this application are usually placed during use. It is only for the convenience of describing this application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation to this application. In addition, the terms "first", "second", "third", etc. are only used for descriptive distinction and cannot be understood as indicating or implying relative importance.

[0080] In the description of the present application, it should also be noted that, unless otherwise clearly specified and defined, the terms "arranged", "installed", "connected", and "coupled" should be understood in a broad sense. For example, it may be a fixed connection, a detachable connection, or an integral connection; it may be a mechanical connection or an electrical connection; it may be directly connected, or indirectly connected through an intermediate medium, and it may be the communication inside two components. For those of ordinary skill in the art, the specific meanings of the above terms in the present application can be understood according to specific circumstances.

[0081] In the present application, all embodiments, implementation manners, and features of the present application can be combined with each other without contradiction or conflict. In the present application, conventional devices, apparatuses, components, etc. can either be commercially purchased or self-made according to the content disclosed in the present application. In the present application, for the purpose of highlighting the key points of the present application, some conventional operations, devices, apparatuses, and components are omitted or only briefly described.

[0082] The above are only the preferred embodiments of the present application and are not intended to limit the present application. For those skilled in the art, the present application can have various changes and modifications. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included within the protection scope of the present application.

Claims

1. A method for measuring the tensile strength of ribbed steel bars, using a system for measuring the tensile strength of ribbed steel bars Comprising: A tensile testing machine, including a 1# tensile testing machine and a 2# tensile testing machine, used for measuring the tensile process of ribbed steel bar specimens. The 1# tensile testing machine and the 2# tensile testing machine are arranged adjacent to each other; A manipulator, used for clamping the ribbed steel bar specimens and transporting them to the tensile testing machine; A specimen rack, including two 1# specimen racks and two 2# specimen racks. The two 2# specimen racks are arranged adjacent to each other, and the two 2# specimen racks are respectively arranged opposite to the 1# tensile testing machine and the 2# tensile testing machine; The two 1# specimen racks are arranged obliquely with respect to the center line of the manipulator; Specifically, the angle α between the center line of the 1# specimen rack and the center line of the manipulator is 27° - 33°; The 1# specimen rack and the 2# specimen rack include a column, a cross bar, a tilting bar, a stabilizing bar, and a base, where the column is connected to the base; The tilting bar is arranged obliquely with respect to the column, with one end connected to the column and the other end being a free end; The free end of the tilting bar is perpendicularly connected to the stabilizing bar; The stabilizing bar is used to support the ribbed steel bar specimens; The cross bar is fixedly connected to the columns arranged on the left and right; Specifically, the angle β between the tilting bar and the horizontal direction is 10° - 25°; At least three concave grooves are arranged on the stabilizing bar for placing the ribbed steel bar specimens; The column spacing D1 of the 1# specimen rack: the tilting bar spacing D2 is 2.8:1 - 3:1; The column spacing D3 of the 2# specimen rack: the tilting bar spacing D4 is 1.5:1 - 1.7:1; The method comprises the following steps: Step 1, the ribbed steel bar specimens are placed on the specimen rack according to the angle of 45° between the longitudinal ribs of the ribbed steel bar specimens and the plane where the center line of the ribbed steel bar specimens is located and the horizontal plane. Ribbed steel bar specimens with a diameter specification of 12mm - 31mm are placed on the 1# specimen rack, and ribbed steel bar specimens with a diameter specification of 32mm - 40mm are placed on the 2# specimen rack; Step 2, the manipulator automatically picks ribbed steel bar specimens of different specifications and transports them to the tensile testing machine for clamping; Step 3, adjust the video extensometer camera of the tensile testing machine to face the transverse ribs of the clamped ribbed steel bar specimens; Measure the ribbed steel bar specimens in a non-contact manner to obtain tensile deformation data; The video extensometer identifies the transverse ribs on the surface of the ribbed steel bar specimens as marking points and synchronously measures and tracks the local strains of 10 marking points; Step 4, the tensile test starts. The video extensometer is controlled by the control system in the control room. The test rate is controlled by the strain rate according to GB / T228.

1. The local strains of 10 marking points are tracked in real time, the local strain maximum point is calculated and marked, and the tracking is carried out until the specimen breaks; Step Five: Obtain a force-elongation curve diagram and obtain the maximum force from the curve diagram F m , the total elongation at maximum force A gt . After the specimen fractures, measure the elongation after fracture A ; During the clamping process of the threaded steel tensile specimen, adjust the size of the video extensometer recognition point according to the specimen diameter specification: For a diameter specification of 12mm - 20mm, the identification point size is 90dpi * 70dpi; For a diameter specification of 21mm - 30mm, the identification point size is 90dpi * 80dpi; Diameter specification: 31mm - 40mm, recognition point size: 128dpi * 80dpi.

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