A device for testing residual stress of dissimilar steel laser welding

Abstract

The utility model provides a kind of dissimilar steel laser welding residual stress testing device, comprising: pedestal platform, three-axis movement module, drilling unit, strain measurement module and data processing unit;Pedestal platform uses aluminium alloy frame, built-in horizontal adjusting mechanism, three-axis movement module is driven by stepper motor, precision ±0.01mm, realize measuring point accurate positioning, drilling unit integrates high-precision electric spindle (rotating speed 0-10,000rpm adjustable), is equipped with diameter 2mm hard alloy drill bit, drilling depth is controlled in real time by laser displacement sensor, strain measurement module includes BE120-2CA type three-way strain flower and static resistance strain gauge, strain release data (epsilon 0, epsilon 45 , epsilon 90 ) after drilling are collected in real time, data processing unit is built-in embedded system, residual stress (sigma x , sigma γ ) is automatically calculated and generates stress distribution nephogram, by automation drilling and strain acquisition technology, the quick, high-precision measurement of residual stress of welded joint is realized, suitable for the quality evaluation and process optimization of dissimilar steel weld.

Description

Technical Field

[0001] This utility model relates to the field of welding residual stress testing technology, and in particular to a residual stress testing device suitable for laser-welded joints of dissimilar steels. By integrating the blind hole method and automated measurement technology, it achieves high-precision and high-efficiency detection of residual stress distribution. Background Technology

[0002] In laser welding of dissimilar steels, significant residual stress is easily generated in the weld area due to differences in the thermophysical properties of the materials, affecting structural safety and service life. Traditional residual stress testing methods (such as X-ray method and blind hole method) require manual operation, which is inefficient and susceptible to human error. Existing equipment is unable to quickly and accurately measure the non-uniform stress distribution in dissimilar steel welds.

[0003] Currently, residual stress testing devices on the market mainly include X-ray diffractometers, ultrasonic testing instruments, and manual blind hole method devices. While X-ray diffraction offers high precision, the equipment is expensive, operation is complex, and it can only measure surface stress. Ultrasonic testing is a non-destructive testing method, but its accuracy is low, making it unsuitable for the complex stress fields of dissimilar steel welds. Traditional manual blind hole methods require operators to manually drill holes, attach strain gauges, and record data, making the entire testing process time-consuming, with single-point testing exceeding 15 minutes. Furthermore, measurement accuracy is greatly affected by the operator's skill level, resulting in poor repeatability. In addition, existing equipment generally lacks automated positioning capabilities, making it extremely inefficient for multi-point measurement needs. Data processing relies on manual calculations, which are prone to errors and cannot generate stress distribution cloud maps in real time. Therefore, a residual stress testing device for laser welding of dissimilar steel is needed to address these issues. Utility Model Content

[0004] This invention aims to solve the problems of low efficiency, insufficient accuracy, low automation, and weak data processing capabilities in existing residual stress testing devices for laser welding of dissimilar steels.

[0005] This utility model provides a residual stress testing device for laser welding of dissimilar steels, comprising: a base platform, a triaxial moving module, a drilling unit, a strain measurement module, a data processing unit, and a specimen fixing mechanism; the triaxial moving module is installed on the base platform, the drilling unit is fixed on the triaxial moving module, the specimen fixing mechanism is provided on the surface of the base platform, the strain measurement module is provided around the drilling unit, and the data processing unit is electrically connected to the strain measurement module.

[0006] Furthermore, the base platform includes: an aluminum alloy frame, a leveling mechanism, and a positioning scale; the aluminum alloy frame adopts a rigid structural design, the leveling mechanism is installed at the bottom of the aluminum alloy frame, and the positioning scale is engraved on the surface of the aluminum alloy frame.

[0007] Furthermore, the three-axis motion module includes: X / Y / Z axis slides, stepper motor groups, and a guide rail system; the X / Y / Z axis slides are mounted on the base platform, the stepper motor groups drive the movement of the three-axis slides respectively, and the guide rail system adopts precision linear guide rails.

[0008] Furthermore, the drilling unit includes: a high-precision electric spindle, a carbide drill bit, and a laser displacement sensor; the high-precision electric spindle has an adjustable speed range of 0-10,000 rpm, the carbide drill bit has a diameter of 2 mm, and the laser displacement sensor is installed on the side of the electric spindle.

[0009] Furthermore, the strain measurement module includes: a foil strain gauge, a static resistance strain gauge, and a signal amplifier; the foil strain gauge adopts the BE120-2CA type triaxial strain gauge, the static resistance strain gauge is connected to the strain gauge, and the signal amplifier amplifies the strain signal.

[0010] Furthermore, the data processing unit includes an embedded processor, a stress calculation module, and a display screen; the embedded processor adopts an ARM architecture processor, the stress calculation module has a built-in residual stress calculation algorithm, and the display screen is a touch screen display interface.

[0011] Beneficial effects:

[0012] 1. In this utility model, the three-axis movement module uses a high-precision stepper motor to drive the X / Y / Z axis slides, achieving a positioning accuracy of ±0.01mm. Combined with a laser displacement sensor, it monitors the drilling depth in real time, ensuring drilling accuracy is controlled within ±0.02mm. The strain measurement module uses a BE120-2CA type triaxial strain rosette, which has a high sensitivity coefficient and a strain measurement accuracy of up to 1με. The static resistance strain gauge uses a quarter-bridge method, and the signal amplifier effectively eliminates the effects of temperature drift and noise. The data processing unit incorporates a residual stress calculation algorithm based on elasticity theory, automatically converting strain data to stress values ​​with a calculation error of less than 5%. The overall system achieves high-precision and high-reliability residual stress measurement, reducing the measurement error by more than 40% compared to traditional manual methods, significantly improving the accuracy and stability of residual stress detection in dissimilar steel welds.

[0013] 2. The three-axis motion module enables automated multi-point measurement. Users only need to preset the coordinates of the measurement points, and the system automatically completes the entire process of positioning, drilling, and data acquisition. The single-point test time is reduced to less than 3 minutes, improving efficiency by more than 5 times. The electric spindle speed of the drilling unit is adjustable to adapt to the drilling needs of different materials. The stress calculation module of the data processing unit supports real-time calculation and cloud map generation. After the test is completed, an intuitive stress distribution map can be output to assist process personnel in quickly locating stress concentration areas. The base platform adopts a modular design, and the specimen fixing mechanism can be adapted to welding specimens of different sizes. The total weight of the equipment does not exceed 30kg, which is convenient for on-site testing and fully embodies the concepts of high efficiency, intelligence, and practicality. Attached Figure Description

[0014] Figure 1 This is a three-dimensional structural schematic diagram of the present invention;

[0015] Figure 2 This is a schematic diagram of the base platform structure of this utility model;

[0016] Figure 3 This is a schematic diagram of the three-axis moving module structure of this utility model;

[0017] Figure 4 This is a schematic diagram of the drilling unit structure of this utility model;

[0018] Figure 5 This is a schematic diagram of the strain measurement module structure of this utility model;

[0019] Figure 6 This is a schematic diagram of the data processing unit interface of this utility model.

[0020] In the figure, the correspondence between the component names and the attached drawing numbers is as follows: Base platform 1, Aluminum alloy frame 101, Horizontal adjustment mechanism 102, Positioning scale 103, Three-axis movement module 2, X / Y / Z axis slide table 201, Stepper motor group 202, Guide rail system 203, Drilling unit 3, High-precision electric spindle 301, Carbide drill bit 302, Laser displacement sensor 303, Strain measurement module 4, Foil strain gauge 401, Static resistance strain gauge 402, Signal amplifier 403, Data processing unit 5, Embedded processor 501, Stress calculation module 502, Display screen 503, Specimen fixing mechanism 6. Detailed Implementation

[0021] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present utility model. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments.

[0022] As attached Figure 1 To be continued Figure 6 As shown:

[0023] This embodiment provides a residual stress testing device for laser welding of dissimilar steels, including: a base platform 1, a triaxial moving module 2, a drilling unit 3, a strain measurement module 4, a data processing unit 5, and a specimen fixing mechanism 6; the triaxial moving module 2 is installed on the base platform 1, the drilling unit 3 is fixed on the triaxial moving module 2, the specimen fixing mechanism 6 is provided on the surface of the base platform 1, the strain measurement module 4 is provided around the drilling unit 3, and the data processing unit 5 is electrically connected to the strain measurement module 4.

[0024] Preferably, the base platform 1 includes: an aluminum alloy frame 101, a horizontal adjustment mechanism 102, and a positioning scale 103; the aluminum alloy frame 101 adopts a rigid structure design, the horizontal adjustment mechanism 102 is installed at the bottom of the aluminum alloy frame 101, and the positioning scale 103 is engraved on the surface of the aluminum alloy frame 101.

[0025] In a specific embodiment: the aluminum alloy frame 101 of the base platform 1 is made of 6061-T6 aluminum alloy, with dimensions of 600mm×400mm×80mm and a frame wall thickness of 8mm. It is integrally cast to ensure rigidity and stability. The horizontal adjustment mechanism 102 uses an M12 screw-type leveling device with an adjustment range of ±20mm. Combined with a precision level, the platform's levelness can be controlled within 0.02mm / m, ensuring the test plane is perpendicular to the drilling direction. The positioning scale 103 uses laser engraving technology with an accuracy of 0.1mm, engraved along the X and Y axes for easy specimen positioning and measuring point marking. The specimen fixing mechanism 6 adopts a quick-release pressure plate design, suitable for welded specimens with thicknesses of 10-50mm. The clamping force is adjustable to ensure the specimen remains stable during testing.

[0026] Preferably, the three-axis motion module 2 includes: an X / Y / Z axis slide 201, a stepper motor group 202, and a guide rail system 203; the X / Y / Z axis slide 201 is mounted on the base platform 1, the stepper motor group 202 drives the three-axis slide to move respectively, and the guide rail system 203 adopts a precision linear guide rail.

[0027] In a specific embodiment: the X-axis travel of the three-axis motion module 2 is 300mm, the Y-axis travel is 200mm, and the Z-axis travel is 100mm, covering the testing requirements of conventional welded specimens. The stepper motor assembly 202 adopts a 57-type hybrid stepper motor with a step angle of 1.8°, combined with a 1:10 reducer and a ball screw (lead 5mm), achieving a minimum movement resolution of 0.01mm and a repeatability of ±0.01mm. The guide rail system 203 adopts a THK brand precision linear guide rail with a medium preload level to ensure motion accuracy and rigidity, and the movement speed is adjustable from 0-50mm / s. The three-axis motion module 2 is controlled by a PLC or motion control card, supporting manual jogging, automatic positioning, and multi-point sequence measurement modes. Users can input the coordinates of the measurement points on the touch screen of the data processing unit 5, and the system automatically completes the positioning.

[0028] Preferably, the drilling unit 3 includes: a high-precision electric spindle 301, a carbide drill bit 302, and a laser displacement sensor 303; the high-precision electric spindle 301 has an adjustable speed range of 0-10,000 rpm, the carbide drill bit 302 has a diameter of 2 mm, and the laser displacement sensor 303 is installed on the side of the electric spindle 301.

[0029] In a specific embodiment: the high-precision electric spindle 301 uses a permanent magnet synchronous motor with a rated power of 500W, a speed adjustment range of 0-10,000rpm, radial runout less than 0.005mm, and axial runout less than 0.003mm, ensuring the roundness and perpendicularity of the drilled hole. The carbide drill bit 302 is made of YG8 tungsten-cobalt alloy material, with a diameter of 2.0±0.01mm, a point angle of 118°, and a helix angle of 30°, suitable for drilling steel. The drill bit length is 50mm, and the effective cutting edge length is 20mm. The laser displacement sensor 303 adopts the triangulation principle, with a measurement range of 0-50mm, a resolution of 0.01mm, and a sampling frequency of 1kHz. It monitors the drilling depth in real time and feeds it back to the control system. When the depth reaches the preset value (usually 0.5-1.0mm, approximately 0.25-0.5 times the hole diameter), the Z-axis automatically stops and retracts to avoid drilling too deep and affecting the measurement accuracy. During drilling, the temperature can be reduced and drill cuttings can be flushed away by spraying coolant, keeping the test area clean.

[0030] Preferably, the strain measurement module 4 includes: a foil strain gauge 401, a static resistance strain gauge 402, and a signal amplifier 403; the foil strain gauge 401 adopts a BE120-2CA type triaxial strain gauge, the static resistance strain gauge 402 is connected to the strain gauge 401, and the signal amplifier 403 amplifies the strain signal.

[0031] In a specific embodiment: the foil strain gauge 401 uses a constantan foil strain gauge with a resistance of 120Ω and a sensitivity coefficient K = 2.08. Three strain gauges are distributed along the 0°, 45°, and 90° directions, respectively, with a gauge length of 1mm and a base size of Φ8mm, suitable for blind-hole method measurement. Before bonding, the specimen surface needs to be sanded, cleaned, and neutralized using sandpaper, acetone, and a neutralizing agent. Then, the strain gauge is bonded using 502 glue or epoxy glue, ensuring bonding quality. Resistance is checked after 12 hours of curing. The static resistance strain gauge 402 uses a TDS-530 static data acquisition instrument with 24-bit A / D conversion, a maximum sampling frequency of 100Hz, a strain measurement range of ±20,000με, and an accuracy of 0.1με. It uses a quarter-bridge connection method to connect the strain gauge, providing a stable bridge voltage (typically 2-5V). The signal amplifier 403 amplifies and filters the millivolt-level signal output from the strain gauge, with an adjustable amplification factor of 100-1000 and a bandwidth of 0-100Hz, effectively improving the signal-to-noise ratio and eliminating the effects of temperature drift and electromagnetic interference. Strain data is transmitted in real-time to the data processing unit 5 via a USB interface.

[0032] Preferably, the data processing unit 5 includes: an embedded processor 501, a stress calculation module 502, and a display screen 503; the embedded processor 501 adopts an ARM architecture processor, the stress calculation module 502 has a built-in residual stress calculation algorithm, and the display screen 503 is a touch screen display interface.

[0033] In a specific embodiment: the embedded processor 501 uses an ARM Cortex-A7 dual-core processor with a main frequency of 1.2GHz, runs an embedded Linux operating system, integrates a Qt graphical interface, and has a fast processing speed and short response time. The stress calculation module 502 has a built-in residual stress calculation algorithm based on the ASTM E837 standard, which calculates the stress based on the collected triaxial strain data (ε0, ε...). 45 ε 90 Given the material's elastic constants (elastic modulus E, Poisson's ratio ν), the residual stress (σ) is automatically calculated. x σ γ The display 503 is a 7-inch capacitive touchscreen with a resolution of 1024×600, displaying the test progress, strain curves, and stress cloud diagrams in real time. The user interface is user-friendly and easy to operate. The data processing unit 5 has built-in 32GB of storage space, capable of storing over 1000 sets of test data. It supports USB export and WiFi wireless transmission, facilitating subsequent analysis and report generation.

[0034] Working Principle: The residual stress testing device for laser welding of dissimilar steels is installed on a stable worktable, and the base platform 1 is leveled by the horizontal adjustment mechanism 102. The welded specimen is placed on the base platform 1 and fixed by the specimen fixing mechanism 6, ensuring that the specimen surface is parallel to the test plane. According to the weld location and testing requirements, the coordinates of the measuring points (such as weld center, heat-affected zone, base metal area) are determined. The specimen surface is ground, cleaned, and neutralized using a strain rose pasting tool, and then foil strain roses 401 are pasted, ensuring that the center of the strain rose is aligned with the pre-drilled hole position. After curing for 12 hours, the resistance is checked. The coordinates of the measuring points are input on the display screen 503 of the data processing unit 5. The three-axis movement module 2 automatically positions the device, and the stepper motor group 202 drives the X / Y / Z axis slides 201 to move the drilling unit 3 precisely to the target position. Before drilling, the static resistance strain gauge 402 reads the initial strain value and zeroes it. The drilling program is initiated, and the high-precision electric spindle 301 rotates at a set speed (typically 5000-8000 rpm). The Z-axis slide slowly descends, and the carbide drill bit 302 begins drilling. The laser displacement sensor 303 monitors the drilling depth in real time. When the depth reaches the preset value (typically 0.5-1.0 mm), the Z-axis automatically stops and retracts. During drilling, the strain measurement module 4 synchronously records strain changes, and the signal amplifier 403 amplifies the weak strain signal. The data acquisition frequency is 10 Hz, recording the strain release in three directions (ε0, ε1, ε2, ε3). 45 ε 90 After drilling is completed, the stress calculation module 502 of the data processing unit 5 automatically calculates the residual stress based on the elasticity formula and outputs the transverse stress σ. x Longitudinal stress σ γ The calculation time is less than 1 second, focusing on the principal stress direction. After completing multi-point measurements, the stress calculation module 502 generates a stress distribution cloud map of the weld area based on the stress data from each measuring point, displaying the stress magnitude in pseudo-color to assist in process optimization. Users can view the test results and cloud map on the display screen 503 and export data and images via USB or WiFi. The entire testing process is highly automated, with a single-point test time of less than 3 minutes, significantly improving testing efficiency. This device is reusable and suitable for residual stress testing of laser-welded joints of dissimilar steels such as 304 stainless steel / Q235 carbon steel and Q345 / 16Mn, providing reliable data support for welding process optimization and structural safety assessment.

[0035] The above description is only a preferred embodiment of the present utility model, but the protection scope of the present utility model is not limited thereto. Any equivalent substitutions or changes made by those skilled in the art within the technical scope disclosed in the present utility model, based on the technical solution and the inventive concept of the present utility model, should be included within the protection scope of the present utility model.

Claims

1. A device for testing residual stress in laser welding of dissimilar steels, comprising: The base platform (1), the three-axis moving module (2), the drilling unit (3), the strain measurement module (4), the data processing unit (5), and the specimen fixing mechanism (6) are characterized in that: the three-axis moving module (2) is installed on the base platform (1), the drilling unit (3) is fixed on the three-axis moving module (2), the specimen fixing mechanism (6) is provided on the surface of the base platform (1), the strain measurement module (4) is provided around the drilling unit (3), and the data processing unit (5) is electrically connected to the strain measurement module (4).

2. The residual stress testing device for laser welding of dissimilar steels as described in claim 1, characterized in that: The base platform (1) includes: an aluminum alloy frame (101), a horizontal adjustment mechanism (102), and a positioning scale (103); the aluminum alloy frame (101) adopts a rigid structure design, the horizontal adjustment mechanism (102) is installed at the bottom of the aluminum alloy frame (101), and the positioning scale (103) is engraved on the surface of the aluminum alloy frame (101).

3. The residual stress testing device for laser welding of dissimilar steels as described in claim 1, characterized in that: The three-axis moving module (2) includes: X / Y / Z axis slide (201), stepper motor group (202) and guide rail system (203); the X / Y / Z axis slide (201) is mounted on the base platform (1), the stepper motor group (202) drives the three-axis slide to move respectively, and the guide rail system (203) adopts precision linear guide rail.

4. The residual stress testing device for laser welding of dissimilar steels as described in claim 1, characterized in that: The drilling unit (3) includes: a high-precision electric spindle (301), a carbide drill bit (302), and a laser displacement sensor (303); the high-precision electric spindle (301) has an adjustable speed range of 0-10,000 rpm, the carbide drill bit (302) has a diameter of 2 mm, and the laser displacement sensor (303) is installed on the side of the electric spindle (301).

5. The residual stress testing device for laser welding of dissimilar steels as described in claim 1, characterized in that: The strain measurement module (4) includes: a foil strain gauge (401), a static resistance strain gauge (402), and a signal amplifier (403); the foil strain gauge (401) adopts a BE120-2CA type triaxial strain gauge, the static resistance strain gauge (402) is connected to the strain gauge (401), and the signal amplifier (403) amplifies the strain signal.

6. The residual stress testing device for laser welding of dissimilar steels as described in claim 1, characterized in that: The data processing unit (5) includes: an embedded processor (501), a stress calculation module (502), and a display screen (503); the embedded processor (501) adopts an ARM architecture processor, the stress calculation module (502) has a built-in residual stress calculation algorithm, and the display screen (503) is a touch screen display interface.

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