Device for non-contact measurement of elongation at break by controlling laser irradiation point to track marked line

Abstract

The utility model provides a device for non-contact measurement of elongation at break by controlling a laser irradiation point to track a marked line. According to the device, a shell is fixedly installed on the top of a support, the two sides of the shell are each provided with a servo motor, a light collecting tube and a laser displacement sensor are installed in the shell, the output end of the light collecting tube is connected with an integration box, the tail of the laser displacement sensor is rigidly connected with output shafts of the servo motors, and a signal processing integration box is installed behind the shell. A transmitter and an A / D converter are installed in the signal processing integration box, the servo motor is connected with the signal processing integration box through a servo motor assembly line, and the signal processing integration box is connected with the servo motor control mechanism through a power supply data bus. According to the extensometer, the laser displacement sensor and the light collecting tube are introduced into the extensometer, the measurement precision exceeding that of a common extensometer is obtained through calculation, the problem of compatibility with various tensile machine software and data interfaces is effectively solved, and the extensometer is suitable for various detection scenes such as small-deformation and large-deformation materials.

Description

Technical Field

[0001] The utility model relates to the technical field of inspection and testing equipment, in particular to a device for controlling a laser irradiation point to track a marking line and non-contactly measuring elongation at break. Background Art

[0002] Currently, in material research and development, production, and product quality inspection and testing, it is often necessary to measure the elongation at break (or nominal strain at break) of materials or products. Elongation at break is the ratio of the change in gauge length to the original gauge length when a specimen breaks. Due to differences in material quality, elongation at break test results can vary significantly. To adapt to the testing characteristics of different materials, existing technologies have developed extensometers for different applications. The first type is large-deformation extensometers, which are used for materials with large deformations, such as plastics, rubber, asphalt, black ground film, blue greenhouse film, transparent composite film (bags), and black PE pipes. The second type is video extensometers, which are used for materials with high testing accuracy and small deformations, such as metals, white PVC-U sheets, general transmission V-belts, and special composite films (bags). Although the above two types of extensometers can adapt well to the requirements of inspection and testing, they have exposed many defects in actual use: First, the mechanical extensometer has a gauge clamp that clamps the sample during the test, which interferes with the stress field of the sample and affects the accuracy of the measurement results; second, the video extensometer is expensive and is prone to frame drops during the sample stretching process; third, the extensometer itself cannot determine the moment of sample fracture. The measurement signal needs to be sent to the controller of the tensile testing machine, and the tensile testing machine must make a judgment based on the tensile data, extensometer data, and clock data before the elongation at break can be displayed on the computer software of the tensile testing machine. Fourth, the versatility of these two types of extensometers is not strong. On the one hand, common extensometers cannot take into account multiple application scenarios such as large deformation materials and small deformation materials at the same time; on the other hand, extensometers are generally only compatible with tensile testing machines of specific brands, specifications, and models. For other tensile testing machines, there is still a problem of mismatch between the extensometer and tensile machine interfaces due to different data types of extensometers and different power supply requirements of encoders; fifth, the communication interface is not integrated enough. At present, most tensile testing machines still use two sets of extensometer signal interfaces specially set for large deformation materials and small deformation materials. Summary of the Invention

[0003] The purpose of this utility model is to provide a device for non-contact measurement of elongation at break by controlling the laser irradiation point to track a marking line. The technical problem to be solved by this utility model is to integrate a laser displacement sensor and a light collecting tube into an extensometer. Two servo motors with collinear rotation axes drive the two laser displacement sensors to dynamically track the edges of two moving marking lines during the test, and provide dynamic, real-time feedback on the distance between the positions of the two servo motor rotation axes and the edges of the two marking lines.

[0004] In order to achieve the above purpose, the technical solution of the utility model is:

[0005] A device for controlling laser irradiation points to track markings and non-contactly measuring elongation at break comprises: a bracket, a housing, a servo motor, a laser displacement sensor, a light collecting tube, a signal processing integrated box, a level, a servo motor cable, a light shielding plate, a tensile machine data cable, a power cable, a light collecting tube output cable, a transmitter, an A / D converter, and a servo motor control mechanism, wherein the servo motor control mechanism comprises: a power supply data bus, a computer, an emergency stop button, a driver, and a power switch. The device comprises a housing fixedly mounted on the top of the bracket, a servo motor is respectively mounted on both sides of the housing, a light collecting tube is mounted on the upper part of the housing, a light shielding plate is mounted on the end of the light collecting tube, an output end of the light collecting tube is connected to the signal processing integrated box via the light collecting tube output cable, a laser displacement sensor is mounted below the light collecting tube, a tail end of the laser displacement sensor is rigidly connected to the output shaft of the servo motor, a signal processing integrated box is mounted at the rear of the housing, a level is mounted on the top of the signal processing integrated box, the servo motor is connected to the signal processing integrated box via the servo motor cable, and the signal processing integrated box is connected to the servo motor control mechanism via the power supply data bus.

[0006] An emergency stop button and a power switch are respectively installed on the driver housing of the servo motor control mechanism in the device. A computer is installed on the upper part of the driver. The computer is connected to the driver through a separate data cable, and is connected to the servo motor, laser displacement sensor, and signal processing integrated box through the data cable in the power supply data bus. It is connected to the tensile machine through the tensile machine data cable. The driver is connected to the servo motor through the servo motor power cable integrated in the power supply data bus and the servo motor group cable. The computer and the driver are connected to the power supply through the power cable.

[0007] The signal processing integrated box in the device is equipped with a transmitter and an A / D converter. The input end of the transmitter is connected to the output end of the light collecting tube through the light collecting tube output line, the output end of the transmitter is connected to the input end of the A / D converter via a data line, and the output end of the A / D converter is connected to the digital signal input end of the computer via a data line.

[0008] The servo motor, laser displacement sensor, transmitter and A / D converter involved in the device are all mature products in the existing technology. The computer is an integrated computer, and the light collecting tube is a self-designed component of this application.

[0009] Compared with the prior art, the positive effects of the present invention are:

[0010] 1. This device incorporates a laser displacement sensor and a light collecting tube into the extensometer, uses the laser irradiation point to accurately lock the edge of the marking line, and calculates through a formula to achieve measurement accuracy that exceeds that of ordinary extensometers.

[0011] 2. When calculating the elongation at break, the device compensates for the offset of the center of the laser irradiation point relative to the edge of the marking line at the moment of specimen fracture, further improving the accuracy of the test results;

[0012] 3. This device enables the extensometer to operate independently and output the elongation at break results, effectively solving the compatibility issues with various tensile testing machine software and data interfaces;

[0013] 4. This device eliminates the measurement accuracy issues of two types of restrained extensometers in the existing technology: the problem of mechanical extensometers causing additional stress on the sample due to clamping the sample, and the problem of video extensometers easily dropping frames due to the bright reflection of the sample;

[0014] 5. The device is suitable for a variety of detection scenarios such as small deformation materials and large deformation materials, and has high promotion value. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] In order to more clearly illustrate the technology of the present invention in the embodiment of the invention, the drawings required for use are briefly introduced. The drawings described below are merely exemplary, and those skilled in the art can also derive other implementation drawings based on the provided drawings without inventive work.

[0016] The structures, proportions, sizes, etc. of the drawings shown in this specification are only used to match the contents disclosed in the specification so that those skilled in the art can understand and read them. They are not intended to limit the conditions under which the present invention can be implemented. Any structural modifications, changes in proportional relationships, or adjustments in size should still fall within the scope of the technical contents disclosed in the present invention without affecting the effects and objectives that can be achieved by the technology of the present invention.

[0017] Figure 1 , a schematic diagram of the main structure of a device for controlling the laser irradiation point tracking marking line and non-contact measurement of elongation at break;

[0018] Figure 2 , a side view schematic diagram of the structure of a device for controlling the laser irradiation point tracking marking line and non-contact measurement of elongation at break;

[0019] Figure 3 , a rear view structural diagram of a device for controlling the laser irradiation point tracking marking line and non-contact measurement of elongation at break;

[0020] Figure 4 , a schematic diagram of the top view of the structure of the device for non-contact measurement of elongation at break by controlling the laser irradiation point tracking marking line;

[0021] Figure 5 , a schematic diagram of the structure of the signal processing integrated box in the device;

[0022] Figure 6 , a three-dimensional connection diagram of a device for controlling the laser irradiation point tracking marking line and non-contact measurement of elongation at break;

[0023] Figure 7 , a schematic diagram of the measurement principle of the present utility model.

[0024] In the figure: 1. bracket, 2. housing, 3. servo motor, 4. laser displacement sensor, 5. light collecting tube, 6. power supply data bus, 7. computer, 8. emergency stop button, 9. driver, 10. power switch, 11. signal processing integrated box, 12. level, 13. servo motor assembly line, 14. sunshade, 15. tensile machine data line, 16. power line, 17. light collecting tube output line, 18. transmitter, 19. A / D converter. DETAILED DESCRIPTION

[0025] The technical solution of the present invention will be further described clearly and completely below with reference to the accompanying drawings.

[0026] See attached Figure 1-6 , installation and connection of the device, the shell 2 is fixed on the upper part of the bracket 1, the two servo motors 3 are fixed on both sides of the shell 2 in a collinear manner, the two light collecting tubes 5 are installed in the upper part of the shell 2, the shading plate 14 is fixed at the end of the light collecting tube 5, the output ends of the two light collecting tubes 5 are respectively connected to the signal processing integrated box 11 through the light collecting tube output line 17, the two laser displacement sensors 4 are correspondingly installed below the two light collecting tubes 5, the tails of the two laser displacement sensors 4 are rigidly connected to the output shafts of the corresponding servo motors 3, the signal processing integrated box 11 is fixed at the back of the shell 2, the level 12 is fixed at the top of the signal processing integrated box 11, the two servo motors 3 are connected to the signal processing integrated box 11 through the servo motor group line 13, and the signal processing integrated box 11 is connected to the servo motor control mechanism through the power supply data bus 6.

[0027] The emergency stop button 8 and the power switch 10 are respectively installed on the outer casing of the driver 9, and the computer 7 is installed on the upper part of the driver 9. The computer 7 is connected to the driver 9 through a separate data line, and is connected to the servo motor 3, the laser displacement sensor 4, and the signal processing integrated box 11 through the data line in the power supply data bus 6. It is connected to the tensile machine through the tensile machine data line 15. The driver 9 is connected to the servo motor 3 through the servo motor power line integrated in the power supply data bus 6 and the servo motor group line 13. The computer 7 and the driver 9 are connected to the power supply through the power line 16.

[0028] The transmitter 18 and the A / D converter 19 are installed in the signal processing integrated box 11. The input end of the transmitter 18 is connected to the output end of the light collecting tube 5 through the light collecting tube output line 17. The output end of the transmitter 18 is connected to the input end of the A / D converter 19 via a data line. The output end of the A / D converter 19 is connected to the digital signal input end of the computer 7 via the power supply data bus 6.

[0029] Before use, power the device with the power cord 16 and turn on the power switch 10. The two servo motors 3, two laser displacement sensors 4, signal processing integrated box 11, computer 7, and servo driver 9 are powered on. Observe the level 12 and adjust the bracket 1 to ensure that the housing 2, servo motor 3, and laser displacement sensor 4 are always level. Click the start button on the touch screen of computer 7 to officially enter the pre-test preparation procedure: the servo motor 3 drives the laser displacement sensor 4 to scan the sample in the forward / reverse direction. In the early stage of scanning, find the vertical distance between the sample and the center line of the servo motor output shaft and record it (see Figure 7 At the end of the scan, the computer 7 captures the photoelectric signal characteristics of the laser reflected from the blank area, the marking area, and the edge of the marking, and uses this as the basis for identifying the edge of the marking. After the edge of the marking is identified, the scan ends, and the servo motor 3 reverses to control the laser irradiation point to lock the edge of the marking, that is, to ensure that the center of the laser irradiation point is always at the edge of the marking.

[0030] After the test begins, the device automatically tracks the edge of the marking line, and the test steps are displayed and operated through the human-machine interface of computer 7. As the fixture head on the tensile testing machine moves, the specimen is continuously stretched, and the two marking lines also move upward accordingly. After the reflected laser generated by the laser displacement sensor 4 enters the light collecting tube 5, it undergoes multiple mirror reflections inside the light collecting tube 5 and is focused and projected onto the silicon photocell inside the tube. The silicon photocell converts the laser reflection signal into a photocurrent signal and transmits it to the signal processing integrated box 11 composed of the transmitter 18 and the A / D converter 19. In the signal processing integrated box 11, the photocurrent signal is standardized by the transmitter 18 and output as a standard current signal. The standard current signal generated by the transmitter 18 is transmitted to the A / D converter 19, converted into a photocurrent digital signal, and output to the input terminal of computer 7. The tensile sensor data of the tensile testing machine is output to the input terminal of computer 7 in digital form via the tensile machine data line 15. Computer 7 converts the photocurrent digital signal into a laser reflection intensity digital signal using a set formula to eliminate the influence of the reflected laser receiving angle and receiving distance on the photoelectric signal. The laser reflection intensity digital signal is used to identify the signal characteristics of the edge of the sample marking and calculate the offset of the laser irradiation point relative to the edge of the marking. It is the key variable for the laser irradiation point to lock the edge of the marking. During the test, computer 7 continuously compares the tension data of the tension sensor for two consecutive sampling cycles, and automatically identifies whether the sample is broken through the set calculation program. When computer 7 recognizes that the sample is broken, it immediately uses the tensile strain ε corresponding to the moment of fracture as the elongation at fracture, and displays it fixedly on the display screen of computer 7, and the test ends.

[0031] The above description is only a non-limiting embodiment of the present invention, and a large number of embodiments can be derived therefrom. For ordinary technicians in this field, without departing from the inventive concept of the present invention and without making creative work, several modified and improved embodiments can be made, which all fall within the scope of protection of the present invention.

Claims

1. A device for controlling a laser irradiation point to track a marking line for non-contact measurement of elongation at break, comprising: A bracket (1), a shell (2), a servo motor (3), a laser displacement sensor (4), a light collecting tube (5), a signal processing integrated box (11), a level (12), a servo motor assembly line (13), a light shield (14), a tensile machine data line (15), a power line (16), a light collecting tube output line (17), a transmitter (18), an A / D converter (19), and a servo motor control mechanism, wherein the servo motor control mechanism includes: a power supply data bus (6), a computer (7), an emergency stop button (8), a driver (9), and a power switch (10), characterized in that: the device is fixed with a shell (2) on the top of the bracket (1), and a servo motor (3) is respectively installed on both sides of the shell (2). The shell ( 2) is provided with a light collecting tube (5) at the upper part, a light shielding plate (14) is provided at the end of the light collecting tube (5), the output end of the light collecting tube (5) is connected to the signal processing integrated box (11) through the light collecting tube output line (17), a laser displacement sensor (4) is provided below the light collecting tube (5), the tail of the laser displacement sensor (4) is rigidly connected to the output shaft of the servo motor (3), a signal processing integrated box (11) is provided at the rear of the housing (2), a level (12) is provided at the top of the signal processing integrated box (11), the servo motor (3) is connected to the signal processing integrated box (11) through the servo motor group line (13), and the signal processing integrated box (11) is connected to the servo motor control mechanism through the power supply data bus (6).

2. The device for non-contact measurement of elongation at break by controlling the laser irradiation point and tracking the marking line according to claim 1, characterized in that: An emergency stop button (8) and a power switch (10) are respectively installed on the housing of the driver (9) of the servo motor control mechanism in the device. A computer (7) is installed on the upper part of the driver (9). The computer (7) is connected to the driver (9) through a separate data line, and is connected to the servo motor (3), the laser displacement sensor (4), and the signal processing integrated box (11) through the data line in the power supply data bus (6). It is connected to the tensile machine through the tensile machine data line (15). The driver (9) is connected to the servo motor (3) through the servo motor power line integrated in the power supply data bus (6) and the servo motor group line (13). The computer (7) and the driver (9) are connected to the power supply through the power line (16).

3. The device for non-contact measurement of elongation at break by controlling laser irradiation points and tracking marking lines according to claim 1, characterized in that: The signal processing integrated box (11) in the device is equipped with a transmitter (18) and an A / D converter (19). The input end of the transmitter (18) is connected to the output end of the light collecting tube (5) via the light collecting tube output line (17). The output end of the transmitter (18) is connected to the input end of the A / D converter (19) via a data line. The output end of the A / D converter (19) is connected to the digital signal input end of the computer (7) via a power supply data bus (6).

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