Thermal multi-parameter integrated dynamic precision measurement method for microstructure

Abstract

The invention discloses a thermal multi-parameter integrated dynamic precision measurement method for a fine structure. A twin light field is constructed through a variable-structure optical fiber bundle with a square inner part and a round outer part to realize thermal multi-parameter measurement of the fine structure; comprising the following steps: assembling a light path for acquiring twin speckles: splitting coherent light emitted by laser into light A and light B; a is imaged into reference twinborn speckles; the light B irradiates a measured structure after passing through an optical circulator and a central square-core emitting optical fiber of an inner-square outer-circle optical fiber bundle, reflected light forms static twinning speckles of reflection imaging of the light B after passing through a peripheral receiving optical fiber of the inner-square outer-circle optical fiber bundle and the optical circulator, and a twinning speckle light field is obtained through superposition; constructing a three-dimensional twin light field comprising a spatial position and other information; a to-be-measured dynamically changing three-dimensional twinning light field is obtained, and temperature, stress and vibration parameters are obtained by analyzing the dynamically changing three-dimensional twinning light field and combining material mechanical parameters. According to the invention, synchronous measurement of multiple parameters of temperature, stress and vibration of the fine structure under a dynamic working condition is realized.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of mechanical dynamic precision measurement, and particularly relates to a thermal force multi-parameter integrated dynamic precision measurement method for microstructures. BACKGROUND

[0002] In the modern engineering field, especially in the processing and application of microstructures, it is crucial to accurately obtain the thermal, force and vibration parameters of microstructures. Taking a micro-milling cutter as an example, in the process of high-speed milling, the temperature, stress and vibration parameters have a significant influence on the processing quality, tool life and the final performance of the workpiece. However, the current measurement technology for these parameters of microstructures has many limitations.

[0003] In terms of temperature measurement, common methods such as embedding thermocouples have applications in some conventional scenarios, but for microstructures such as micro-milling cutters, which are small in size, high in speed and fast in heat dissipation, this method is difficult to adapt. For example, when a small spherical milling cutter is used for high-speed machining of complex curved surfaces, embedding thermocouples will damage the structure of the cutter due to its small size, and it is difficult to accurately measure the temperature distribution along the cutting edge in real time. For example, the prior art document CN204843716U discloses an infrared radiation thermometer for measuring cutting temperature in high-speed machining, which mentions that in the process of high-speed milling of small cutters, traditional temperature measurement methods are difficult to apply due to their respective limitations. At the same time, methods such as infrared radiation thermometers can overcome some problems to some extent, but they can only measure a single parameter of temperature.

[0004] For stress measurement, in the process of micro-milling, due to the limitation of machining allowance, the feed per tooth of the cutter is extremely small, even smaller than the size of the material internal grains, which makes the cutting process complex and makes it difficult to measure and control the residual stress of the machined surface. Currently, X-ray diffraction method is commonly used to measure the residual stress of the workpiece surface, such as in the micro-milling experiment of high-temperature alloy GH4169 with different grain sizes after heat treatment, the residual stress value of the machined surface in the feed direction of the workpiece is measured by this method, and the prior art document "Simulation and experimental research on residual stress of GH4169 high-temperature alloy micro-milling considering grain size", but this method is also only for a single parameter of stress, and in the measurement process, the equipment operation is complex, the measurement environment is high, and it is difficult to obtain stress data in real time and conveniently during dynamic processing.

[0005] In the field of vibration measurement, for the dynamic characteristics measurement of micro-milling tool tip, the traditional measurement method of using force hammer to excite the tool tip is not applicable due to the small diameter of micro-milling tool (generally within 1mm), large length-diameter ratio, and easy breakage of tool tip. The existing technology, such as using a micro pulse force hammer to excite the micro-milling tool at a set position on the tool holder, and then using a scanning laser vibration meter to measure the vibration displacement of the set measurement point on the milling tool, to obtain the dynamic characteristics of the micro-milling tool tip, is described in the existing technology with publication number CN104227504A, but this is only the measurement of a single parameter of vibration.

[0006] At the same time, there has been some progress in the measurement of these parameters by fiber optic sensors. Ma, S. et al. in the article "Fiber optic sensors for high temperature monitoring: a review", Mater, V. et al. in the article "Measurement of gradient strain fields using fiber optic sensors", and Kishor, P. Dhinakaran, D. et al. in the article "Fiber optic vibration sensor" published in Optoelectronics, all relate to this aspect.

[0007] The existing technology with publication number CN110793664B discloses a multi-parameter sensing transformer fiber sensor installation arrangement method, which deploys temperature measuring fiber sensors, winding pressure shoe dynamic pressure fiber sensors, vibration fiber sensors, and partial discharge fiber sensors to achieve comprehensive sensing of transformer state, internal temperature, pressure, vibration, and partial discharge multi-parameters, but this scheme cannot be used for multi-parameter measurement of micro-structures.

[0008] However, most existing measurement technologies can only measure a single parameter in the same space and time, and different parameters require different measurement methods and equipment. In actual engineering, many scenarios require simultaneous acquisition of temperature, stress, vibration, and other parameters of micro-structures to achieve precise control and optimization of the processing process. The above traditional measurement methods are obviously difficult to meet the demand of synchronous measurement. SUMMARY

[0009] 1. Technical problems to be solved: To effectively overcome the difficulty of multi-parameter integrated measurement of micro-structures, the present application proposes a thermal force multi-parameter integrated dynamic precision measurement method for micro-structures. This method constructs a three-dimensional light field through fiber bundle imaging speckle, and further analyzes the three-dimensional light field, which is expected to realize synchronous and accurate measurement of multiple parameters such as temperature, stress, and vibration of micro-structures, and provides a new and efficient solution for the field of micro-structure parameter measurement.

[0010] 2. Technical solutions: The application discloses a method for dynamically and precisely measuring thermal and force multi-parameters of microstructures. Step one: assemble an optical path for acquiring twin speckles; the optical path comprises: coherent light emitted by a laser light source is conducted through a multi-mode square core optical fiber, and then is incident to a beam splitter to be split into sub-light A and sub-light B; the sub-light A is directly projected to an imaging device to form a reference twin speckle of direct imaging of the sub-light A; the sub-light B enters a 1-port of an optical circulator from a 2-port to be conducted out, and then enters a center square core emitting optical fiber of an inner square outer circle optical fiber bundle to be emitted to form a spatial light field in a real physical space, which is used for irradiating a surface of a measured structure in measurement; reflected light of the surface of the measured structure is received by a peripheral receiving optical fiber of the inner square outer circle optical fiber bundle, is conducted into a 2-port of the optical circulator and is conducted out from a 3-port, and then is projected to the imaging device to form a static twin speckle of reflection imaging of the sub-light B; the position of the imaging device is adjusted to make the reference twin speckle and the static twin speckle superimposed in a same field of view to generate a superimposed twin speckle light field; Step two: construct a three-dimensional twin light field digital model; combine a two-dimensional twin speckle image including spatial information acquired with other information to generate a three-dimensional twin light field including quantized speckle intensity of the spatial position and the other information; the other information includes gray scale, phase and polarization parameters; Step three: acquire a dynamically changed three-dimensional twin light field; change working conditions of the measured structure to make one or more parameters of temperature, stress and vibration of the measured structure change, the change disturbs the light field emitted by the sub-light B in a real space, and then is collected by a receiving optical fiber bundle; the disturbance causes the change of the light field in the real physical space to directly cause the change of a twin speckle image, and then a corresponding dynamically changed three-dimensional twin light field is obtained; Step four: multi-parameter analysis and synchronous output; extract high-frequency information from the dynamically changed three-dimensional twin light field, analyze vibration parameters of a measured object according to the high-frequency information; extract low-frequency information, acquire the change of temperature of the measured object based on a calibration relationship between gray scale and temperature; acquire the change of stress of the measured object based on dynamic changes of speckle gathering degrees in the three-dimensional twin light field and in combination with material mechanics parameters; and synchronously output the acquired parameters.

[0011] Further, in step one, the laser light source is a helium-neon laser with a wavelength of 632.8 nm or other coherent or non-coherent light sources that facilitate the generation of adjustable light fields; the beam splitter is a beam splitter with adjustable splitting ratio, and the intensity distribution of sub-light A and sub-light B is adjusted by changing the splitting ratio during measurement; the inner square and outer round fiber bundle is composed of multiple co-axial fibers, the middle fiber is a square core emitting fiber, and the surrounding of the square core fiber is a plurality of receiving fibers with different cross-sectional structures to form a fiber bundle probe, the number and spacing of the receiving fibers are configured according to the design of the light field; the different cross-sectional structures of the receiving fibers and their probes include trapezoidal, circular truncated cone, wavy, truncated cone, truncated hemisphere, and circular; the spacing between the central fiber and the receiving fibers is determined through modeling analysis according to the construction needs of the twin light field field of view.

[0012] Further, step two specifically includes: S21: synchronously collecting twin speckle images by a high-speed camera; S22: obtaining the spatial coordinate information of the measured structure in the image, obtaining the gray level, phase, and polarization information corresponding to each coordinate in the image; taking the spatial information as the XY axis, taking one of the gray level, phase, and polarization parameters as the Z axis as needed to construct a three-dimensional twin light field or taking the gray level, phase, and polarization parameters as the Z axis respectively to construct space-gray level, space-phase, and space-polarization information and further construct multiple parallel three-dimensional twin light fields; the three-dimensional twin light field includes a plurality of scatter points containing spatial information XY and gray level, phase, and polarization information Z; S23: calibrating the reference light field; in the static state of the measured structure, a plurality of frames of twin speckle images are collected to construct an initial three-dimensional twin light field as a reference.

[0013] Further, in step three, the measured microstructure is installed on a high-speed milling experiment platform to simulate the working conditions of the milling process, so that the measured structure produces multi-parameter changes including temperature, stress, vibration, and phase; a preset acquisition frequency is obtained to obtain dynamic twin speckle images; and a three-dimensional twin light field corresponding to each twin speckle image is constructed for multi-parameter analysis.

[0014] Further, step four specifically includes: S41: using a high-frequency filtering algorithm to extract high-frequency fluctuation information from the dynamically changing three-dimensional twin light field, and the high-frequency fluctuation information corresponds to the vibration parameter of the measured structure; S42: segmenting and analyzing the low-frequency information: the gradual disturbance of the twin light field corresponds to the temperature sensitive area, the gray value change is obtained from the dynamically changing three-dimensional twin light field, and the temperature value at the corresponding time is obtained based on the preset calibration relationship between the light field change and the temperature; the structural disturbance of the twin light field corresponds to the stress sensitive area, and the change of the scatter point aggregation degree of the dynamically changing three-dimensional twin light field is obtained, and the stress value is derived combined with the material mechanics parameters. S43: The time alignment of the temperature, stress and vibration parameters is performed by the time stamp recorded by the image acquisition card, and time-consistent multi-parameter data is obtained.

[0015] Further, the high-frequency fluctuation information in step S41 includes high-frequency fluctuation frequency and amplitude, and instantaneous change rate of light field gray value, phase and polarization information; the vibration speed and vibration amplitude of the structure are determined by the high-frequency fluctuation information.

[0016] Further, the change of the scattering point aggregation degree in the dynamic three-dimensional twin light field is obtained in step S42, and the stress value is derived in combination with the material mechanics parameters, specifically: the deformation of the measured object is coded by analyzing the structural change characteristics of the disturbed twin light field and fusing the measured structure mechanics characteristics, wherein the structural change characteristics include the changes of the twist, fractal characteristics and geometric characteristic parameters.

[0017] Further, the method further includes the following step five: parameter optimization; the temperature, stress and vibration parameters obtained in step four are compared with the actual parameters, the beam splitting ratio of the beam splitter, the spatial parameters of the receiving optical fiber and the filtering threshold are adjusted, and the measurement accuracy and dynamic response speed are improved.

[0018] 3. Beneficial effects: (1) The microstructure thermal force multi-parameter integrated dynamic precision measurement method disclosed in the scheme can realize the synchronous measurement of the temperature, stress and vibration multi-parameters of the microstructure (such as a micro-milling cutter) under dynamic working conditions by using the special structure reflective light intensity modulation optical fiber bundle and three-dimensional light field analysis technology, and solves the technical bottleneck that the multi-parameter measurement cannot be implemented synchronously.

[0019] (2) The microstructure thermal force multi-parameter integrated dynamic precision measurement method disclosed in the scheme proposes a variable structure inner square outer circle twin light field, a coherent light is emitted by a laser light source, the coherent light is conducted by a multimode square core optical fiber, a beam splitter is used to split the laser light beam conducted by the square core optical fiber into two sub-beams A and B, each of which accounts for a percentage of the original light beam. A beam directly forms A-direct imaging speckle, which is a static "static speckle", B beam enters via the light ring 1 port and is transmitted out of the light ring 2 port, is conducted by the "inner square" square core emitting optical fiber of the inner square outer circle coaxial optical fiber bundle and is emitted, after irradiating the surface of the micro-milling cutter, the reflected light is received by the receiving optical fiber of the "outer circle" and is conducted, enters the light ring 2 port and is transmitted out of the light ring 3 port, and forms B-reflection imaging speckle, which is a "dynamic speckle" that implicitly contains multi-parameter measured information. After superimposing the two speckles, a "twin speckle" is formed, and then the "twin speckle" is constructed into a "three-dimensional twin light field" according to a certain method.

[0020] (3) The microstructure thermal multi-parameter integrated dynamic precision measurement method disclosed in the scheme proposes a design of macro-micro scale regulation of twin light field structure and sensitive range through the surface of the optical fiber; the inner circle outer square fiber bundle realizes differential perception of different parameters through the customized surface structure of the receiving optical fiber, and a multi-parameter sensitive system is constructed. Etching and other processing technologies are used to customize diversified cross-section structures (such as circular truncated cone, truncated cone, inclined shape, wave shape, etc.) of the receiving optical fiber, and the structures are arranged at optimal spatial positions, so that the light conducted by the structures can be reasonably coupled and the twin light field can be regulated. For example, the circular truncated cone can enhance the high-frequency vibration capture capability, the cone can optimize the temperature sensitive characteristics, the inclined shape can improve the strain response accuracy, and the wave shape can realize the differentiated perception of high and low frequency signals.

[0021] (4) The microstructure thermal multi-parameter integrated dynamic precision measurement method disclosed in the scheme differs from the traditional method in that the disturbance of the external light field is converted into analysis and demodulation of the internal “twin light field”; the external light field is the “dynamic speckle” formed by the mixed reflection light of the sub-beam B of the split laser irradiating the micro-milling cutter surface and natural light, and the internal “twin light field” is a three-dimensional light field formed by the “twin speckle” constructed by the superposition of the “static speckle” formed by the direct imaging of the sub-beam A and the “dynamic speckle”. When the temperature, stress, vibration and other parameters of the micro-milling cutter change, disturbances are introduced to the external light field. The disturbance will change the twin light field through the action of the “dynamic speckle”, and the three-dimensional twin light field will have different response to the input of different parameter changes.

[0022] (5) The method can simultaneously realize the integrated dynamic measurement of temperature, strain and vibration of the microstructure; when the temperature, stress, vibration and other multi-parameters of the micro-milling cutter change simultaneously, the three-dimensional twin light field will show a superimposed mixture of multiple characteristics — there are high-frequency fluctuations caused by vibration, there are linear shifts of gray gradient caused by temperature changes, and there are local area distortion and collapse caused by stress. For this composite light field, the demodulation analysis process will accurately capture its multi-dimensional characteristics. BRIEF DESCRIPTION OF DRAWINGS

[0023] Figure 1 It is a schematic diagram of the light path diagram and the twin light field construction method of the application; Figure 2 It is a schematic diagram of the three-dimensional model of the inner circle outer square fiber bundle of the application; Figure 3 It is the corresponding twin light field of the micro-milling cutter when different parameters change in the application; Figure 4 It is the overall flowchart of the application.

[0024] Figure labels: 1. Laser source; 2. Multimode square-core fiber; 3. Beam splitter; 4. Reference twin speckle; 5. Optical circulator; 6. Inner square outer circular fiber bundle; 61. Central square core transmitting fiber of the inner square outer circular fiber bundle; 62. Outer receiving fiber of the inner square outer circular fiber bundle; 7. Structure under test; 8. Static twin speckle. Detailed Implementation

[0025] The present invention will now be described in detail with reference to the accompanying drawings.

[0026] As attached Figure 4 As shown, a dynamic precision measurement method for multiple thermo-mechanical parameters of microstructures is characterized by: constructing a twin optical field by designing a variable-structure fiber bundle with an inner square and an outer circle to achieve the measurement of multiple thermo-mechanical parameters of the microstructure; specifically, it includes the following steps: Step 1: Assemble the optical path for acquiring twin speckle: The optical path includes: coherent light emitted by a laser source is transmitted through a multimode square-core fiber and then incident on a beam splitter to split into sub-beam A and sub-beam B; sub-beam A is directly projected onto the imaging device to form a reference twin speckle for direct imaging of sub-beam A; sub-beam B enters from port 1 of the optical circulator, exits from port 2, and then enters the central square-core emitting fiber of the inner square-outer circular fiber bundle and exits, forming a spatial light field in real physical space, which is used to illuminate the surface of the structure under test during measurement; the reflected light from the surface of the structure under test is received and transmitted by the outer receiving fiber of the inner square-outer circular fiber bundle, enters through port 2 of the optical circulator, exits through port 3, and is projected onto the imaging device to form a static twin speckle for reflection imaging of sub-beam B; the position of the imaging device is adjusted so that the reference twin speckle and the static twin speckle are superimposed in the same field of view to generate a superimposed twin speckle light field; Step 2: Construct a three-dimensional twin light field digital model; combine the acquired two-dimensional twin speckle image, which includes spatial information, with other information to generate a three-dimensional twin light field that includes spatial location and quantized speckle intensity; the other information includes grayscale, phase, and polarization parameters; Step 3: Obtain the dynamically changing three-dimensional twin optical field; change the working conditions of the structure under test, causing one or more parameters such as temperature, stress, and vibration to change. This change will disturb the light field emitted by the perturbation sub-light B in the real space, which will be collected by the receiving fiber bundle; the change in the real physical space light field caused by this perturbation directly causes the change in the twin speckle image, thus obtaining the corresponding dynamically changing three-dimensional twin optical field. Step 4: Multi-parameter analysis and synchronous output; extract high-frequency information from the dynamically changing three-dimensional twin optical field, and analyze the vibration parameters of the measured object based on the high-frequency information; extract low-frequency information, and obtain its temperature change based on the calibration relationship between grayscale and temperature; obtain its stress change based on the dynamic change of the scatter point aggregation degree in the three-dimensional twin optical field and the material mechanical parameters; and output the obtained parameters synchronously.

[0027] Further, in step one, the laser light source is a helium-neon laser with a wavelength of 632.8 nm or other coherent or non-coherent light sources that facilitate the generation of adjustable light fields; the beam splitter is a beam splitter with adjustable splitting ratio, and the intensity distribution of sub-light A and sub-light B is adjusted by changing the splitting ratio during measurement; the inner square and outer round fiber bundle is composed of multiple co-axial fibers, the middle fiber is a square core emitting fiber, and the surrounding of the square core fiber is a plurality of receiving fibers with different cross-sectional structures to form a fiber bundle probe, the number and spacing of the receiving fibers are configured according to the design of the light field; the different cross-sectional structures of the receiving fibers and their probes include trapezoidal, circular truncated cone, wavy, truncated cone, truncated hemisphere, and circular; the spacing between the central fiber and the receiving fibers is determined through modeling analysis according to the construction needs of the twin light field field of view.

[0028] Further, step two specifically includes: S21: synchronously collect twin speckle images by a high-speed camera; S22: obtain the spatial coordinate information of the measured structure in the image, obtain the gray level, phase, and polarization information corresponding to each coordinate in the image; take the spatial information as the XY axis, take one of the gray level, phase, and polarization parameters as the Z axis according to the needs to construct a three-dimensional twin light field, or take the gray level, phase, and polarization parameters as the Z axis respectively to construct space-gray level, space-phase, and space-polarization information and further construct multiple parallel three-dimensional twin light fields; the three-dimensional twin light field includes a plurality of scatter points containing spatial information XY and gray level, phase, and polarization information Z; S23: calibrate the reference light field; collect multiple frames of twin speckle images in the static state of the measured structure to construct an initial three-dimensional twin light field as a reference.

[0029] Further, in step three, the measured microstructure is installed on a high-speed milling experiment platform to simulate the working conditions of the milling process, so that the measured structure produces multi-parameter changes including temperature, stress, vibration, and phase; a preset acquisition frequency is obtained to obtain dynamic twin speckle images; and a three-dimensional twin light field corresponding to each twin speckle image is constructed for multi-parameter analysis.

[0030] Further, step four specifically includes: S41: use a high-frequency filtering algorithm to extract high-frequency fluctuation information from the dynamically changing three-dimensional twin light field, and the high-frequency fluctuation information corresponds to the vibration parameter of the measured structure; S42: segmentally analyze the low-frequency information: the gradual disturbance of the twin light field corresponds to the temperature sensitive area, the gray value change is obtained from the dynamically changing three-dimensional twin light field, and the temperature value at the corresponding moment is obtained based on the preset calibration relationship between the light field change and the temperature; the structural disturbance of the twin light field corresponds to the stress sensitive area, and the change of the scatter point aggregation degree of the dynamically changing three-dimensional twin light field is obtained, and the stress value is derived combined with the material mechanics parameters. S43: The temperature, stress, and vibration parameters are time-aligned by the time stamp recorded by the image acquisition card, and time-consistent multi-parameter data are obtained.

[0031] Further, the high-frequency fluctuation information in step S41 includes high-frequency fluctuation frequency and amplitude, instantaneous change rate of light field gray value, phase, and polarization information; the vibration speed and vibration amplitude of the structure are determined by the high-frequency fluctuation information.

[0032] Further, in step S42, the change of the scattering point aggregation degree in the dynamically changing three-dimensional twin light field is obtained, and the stress value is derived in combination with the material mechanics parameters, specifically: the deformation of the measured object is coded by analyzing the structural change characteristics of the disturbed twin light field and fusing the measured structure mechanics characteristics, wherein the structural change characteristics include twist, fractal characteristics, and change of geometric characteristic parameters.

[0033] Further, it further includes step five: parameter optimization; the temperature, stress, and vibration parameters obtained in step four are compared with actual parameters, the beam splitting ratio of the beam splitter, the spatial parameters of the receiving optical fiber, and the filtering threshold are adjusted to improve the measurement accuracy and dynamic response speed.

[0034] Embodiment: This embodiment takes a micro-milling cutter as an example. During high-speed milling, temperature, stress, vibration, and other parameters have a significant impact on machining quality, tool life, and the final performance of the workpiece, so it is necessary to measure the above-mentioned parameters. The experimental steps are used to illustrate the scheme.

[0035] I. Experimental device construction 1. Core component preparation Laser light source: a helium-neon laser with an output wavelength of 632.8 nm is selected to ensure that the coherence of the light meets the measurement requirements.

[0036] Multimode square core optical fiber: the core size is 100 μm x 100 μm, which is used to conduct the laser beam.

[0037] Beam splitter: adjustable beam splitting ratio (supports 5:5, 6:4, 6.5:3.5, etc.), realizes beam splitting of incident light.

[0038] Inner square and outer circle coaxial optical fiber bundle: the center is a square core transmitting optical fiber, and the periphery is annularly distributed 6 receiving optical fibers with different cross-sectional structures (including circular truncated cone, truncated cone, inclined shape, wave shape, etc. not limited to the shapes shown in the examples, such as Figure 2The spatial parameters (distance 1mm, angle 60°) of the central fiber and the receiving fiber are optimized. The receiving beam of the inner square and outer circle coaxial fiber bundle is determined by modeling analysis according to the construction needs of the twin light field field of view, including the number and shape, and the spatial parameters between the central beam.

[0039] Optical circulator: with 3 ports, realizing one-way transmission of light beams, 1 port in, 2 port out, 2 port in, 3 port out.

[0040] Imaging device: high-speed CCD camera (frame rate ≥1000fps) is used to capture speckle images.

[0041] Data processing terminal: equipped with image acquisition card and special data processing software, supporting three-dimensional light field construction and multi-parameter analysis.

[0042] 2. Optical path assembly As shown in the accompanying Figure 1 , the coherent light emitted by the laser light source is conducted through the multimode square core optical fiber, then incident to the beam splitter, and split into sub-light A and sub-light B. Sub-light A is directly projected to the imaging device to form the direct imaging reference twin speckle of sub-light A. Sub-light B enters through the 1 port of the optical circulator and is transmitted out from the 2 port, and is emitted by the central square core emitting fiber of the inner square and outer circle fiber bundle, and irradiated on the surface of the measured micro-milling cutter. The reflected light of the micro-milling cutter surface is received by the peripheral annular receiving fiber, and after being transmitted out from the 3 port of the optical circulator, it is projected to the imaging device to form the reflected imaging static twin speckle of sub-light B. Adjust the position of the imaging device to ensure that the static speckle and the dynamic speckle are superimposed in the same field of view to form a "twin speckle".

[0043] Two-dimensional and three-dimensional twin light field construction 1. Speckle image acquisition: the twin speckle images are synchronously acquired by the high-speed CCD camera, and the resolution of each image is set to 1024x1024 pixels.

[0044] 2. Three-dimensional light field conversion: the twin speckle images are processed based on the xyz coordinate system, the (x, y) coordinates correspond to the spatial position of the speckle points in the image, and the z axis quantifies the speckle intensity with a gray value (0-255), thereby constructing a three-dimensional twin light field model. The three-dimensional twin light field constructed in this embodiment analyzes the spatial information as the XY axis and the gray information as the Z axis.

[0045] 3. Reference light field calibration: in the static state of the micro-milling cutter, multiple frames of twin speckle images are acquired to construct an initial three-dimensional twin light field as a reference (as shown in the accompanying Figure 3 (a)).

[0046] Three, dynamic measurement process 1. Multi-parameter disturbance introduction: Install the micro-mill on the high-speed milling experiment platform to simulate the actual machining conditions (such as the milling process at a speed of 10000r / min), so that the micro-mill produces temperature, stress, vibration, phase and other multi-parameter changes.

[0047] 2. Dynamic speckle collection: High-speed CCD camera captures real-time twin speckle images under dynamic conditions, collects one frame every 1ms, and records for 30s.

[0048] 3. Three-dimensional light field update: The data processing terminal processes the collected dynamic speckle images in real time, updates the three-dimensional twin light field model, and captures the dynamic changes of the light field (such as the change of the dispersion degree of the scattered points when the temperature changes, the distortion of the light field when the vibration occurs, and the gathering of the scattered points when the stress occurs, as shown in (b), (c), and (d)). Figure 3

[0049] Four, multi-parameter analysis and synchronous output 1. Parameter signal separation: High-frequency filtering algorithm is used to extract high-frequency information from the three-dimensional twin light field, which corresponds to the vibration parameters of the micro-mill.

[0050] Segmented analysis of low-frequency information: The gray value interval of 0-64 corresponds to the temperature sensitive area, and the temperature value is calculated through the gray value change and the temperature calibration relationship, which is obtained by thermocouple calibration experiment in advance; the gray value interval of 65-127 corresponds to the stress sensitive area, and the stress value is derived based on the change of the gathering degree of the scattered points combined with the material mechanics parameters.

[0051] 2. Time synchronization calibration: The analysis results of temperature, stress, and vibration parameters are time-aligned through the time stamp recorded by the image acquisition card to ensure the time consistency of multi-parameter data.

[0052] 3. Result output: The dynamic change trend of temperature, stress, and vibration is output in real-time curve form on the data processing terminal, and the data storage and export are supported, with the format of CSV or Excel.

[0053] Five, experimental verification and optimization 1. Precision verification: Temperature measurement: Compared with the measurement results of the micro infrared thermometer, the error is controlled within ±1℃.

[0054] Stress measurement: Compared with the measurement results of the X-ray diffraction method, the error is controlled within ±1MPa.

[0055] Vibration measurement: Compared with the measurement results of the scanning laser vibration meter, the amplitude measurement error is controlled within ±1μm.

[0056] ​2. Parameter optimization: adjust the beam splitter ratio of the spectroscope, the spatial parameters of the receiving optical fiber, and the filtering threshold according to the experimental results to further improve the measurement accuracy and dynamic response speed.

[0057] Through the above embodiments, the integrated dynamic precision measurement of multiple parameters such as temperature, stress, vibration, and phase of micro-structured tools such as micro-mills can be realized, meeting the real-time monitoring needs in high-speed machining scenarios.

[0058] The purpose of the present application is to overcome the defects of existing micro-structured parameter measurement techniques, such as separation of means, single parameter acquisition, and complex system, and to provide an integrated dynamic precision measurement method for multiple parameters such as temperature, stress, vibration, and phase of micro-structured tools, with the following specific purposes: Realize multi-parameter synchronous measurement: In view of the problem that temperature, stress, vibration and other parameters in the prior art can only be measured separately in the same space-time, and different parameter measurements require different methods and equipment, the present application aims to realize synchronous measurement of temperature, stress, vibration and other parameters of micro-structured tools (such as micro-mills) under dynamic conditions through special structure-based reflective light intensity modulation optical fiber bundle and three-dimensional light field analysis technology, solving the technical bottleneck of multi-parameter measurement difficulty in synchronous implementation.

[0059] Improve the dynamic and precision of measurement: The real-time performance and measurement accuracy of existing measurement methods in dynamic scenarios need to be improved, such as traditional vibration measurement which is easily limited by tool characteristics, and temperature measurement which is difficult to capture rapid temperature distribution. The present application is committed to improving the dynamic response speed and precision of measurement, which can accurately capture the instantaneous state and dynamic change law of each parameter of micro-structured tools during high-speed operation or dynamic change process, meeting the demand of dynamic precision measurement in engineering.

[0060] Simplify the measurement process and reduce the complexity of operation: Existing multi-parameter measurement involves multiple equipment and complex operation, such as X-ray diffraction method for stress measurement which has high requirements for environment and operation. The present application simplifies the measurement process and reduces the requirement for professional skills of operators through integrated measurement device and method, improving the measurement efficiency.

[0061] Adapt to the special measurement environment of micro-structured tools: Micro-structured tools (such as micro-mills) have small size, large aspect ratio, and are easily damaged, and existing measurement methods are difficult to adapt to their special structure and working environment. The present application aims to provide a measurement scheme that can adapt to the characteristics of micro-structured tools, avoid damage to the measured structure, and ensure stable and reliable measurement under complex working conditions.

[0062] Although the present application has been disclosed in its preferred embodiments with reference to the accompanying drawings, it is not intended to limit the present application thereto, and various changes or modifications can be made thereto by those skilled in the art without departing from the spirit and scope of the present application, and the scope of protection of the present application should be defined by the scope of protection of the claims.

Claims

1. A method for dynamically measuring microstructure thermal multi-parameters, characterized in that: The twin light field is constructed by designing a variable-structure optical fiber bundle with an inner square and an outer circle to realize thermal and multi-parameter measurement of microstructures; Specifically, the method comprises the following steps: Step one: assemble an optical path for obtaining twin speckles: the optical path comprises: coherent light emitted by a laser light source is conducted through a multimode square core optical fiber, and then incident to a beam splitter to be split into sub-light A and sub-light B; sub-light A is directly projected onto an imaging device to form a reference twin speckle of direct imaging of sub-light A; sub-light B enters the center square core emitting optical fiber of an inner square and outer circle optical fiber bundle from the 1 port of an optical circulator and is emitted after being guided out from the 2 port, to form a spatial light field in a real physical space, which is used for illuminating the surface of a measured structure in measurement; the reflected light of the measured structure is received by the peripheral receiving optical fibers of the inner square and outer circle optical fiber bundle, enters the 2 port and is transmitted out from the 3 port of the optical circulator, and then is projected onto the imaging device to form a static twin speckle of reflected imaging of sub-light B; the position of the imaging device is adjusted to realize superposition of the reference twin speckle and the static twin speckle in the same field of view, to generate a superimposed twin speckle light field; Step two: construct a three-dimensional twin light field digital model; combine the obtained two-dimensional twin speckle image including spatial information with other information to generate a three-dimensional twin light field including quantized speckle intensity of spatial position and the other information; the other information includes gray scale, phase and polarization parameters; Step three: obtain a dynamically changing three-dimensional twin light field; change the working condition of the measured structure to make one or more parameters of temperature, stress and vibration change, the change will disturb the light field emitted by sub-light B in the real space, and then the disturbance is collected by the receiving optical fiber bundle; the disturbance directly causes the change of the twin speckle image due to the change of the light field in the real physical space, and then the corresponding dynamically changing three-dimensional twin light field is obtained; Step four: multi-parameter analysis and synchronous output; extract high-frequency information from the dynamically changing three-dimensional twin light field, analyze the vibration parameters of the measured object according to the high-frequency information; extract low-frequency information, obtain the change of temperature based on the calibration relationship between gray scale and temperature; obtain the stress change based on the dynamic change of the gathering degree of the speckles in the three-dimensional twin light field, and combine the material mechanics parameters to obtain the stress change; and synchronously output the obtained parameters. In step one, the laser light source is a helium-neon laser with a wavelength of 632.8 nm or other coherent or non-coherent light sources that are conducive to generating adjustable light fields; the beam splitter is a beam splitter with adjustable beam splitting ratio, and the intensity distribution of sub-light A and sub-light B is adjusted by changing the beam splitting ratio during measurement; the inner square and outer circle optical fiber bundle is composed of a plurality of optical fibers with a common central axis, the middle optical fiber is a square core emitting optical fiber, and the square core optical fiber is surrounded by a plurality of receiving optical fibers with different cross-sectional structures to form an optical fiber bundle probe, the number and spacing of the receiving optical fibers are configured according to the needs of the designed light field; the different cross-sectional structures of the receiving optical fibers and the probe include trapezoidal, circular truncated cone, wavy, truncated cone, truncated hemisphere and circular; the spacing between the central optical fiber and the receiving optical fibers is determined after modeling analysis according to the needs of constructing the field of view of the twin light field.

2. The method according to claim 1, wherein the method is characterized by: Step two specifically comprises:

3. The integrated dynamic precision measurement method for multiple thermodynamic parameters of a microstructure according to claim 1, characterized in that: S21: synchronously collect twin speckle images by a high-speed camera; ​ S22: Obtain the spatial coordinate information of the measured structure in the image, obtain the gray, phase, and polarization information corresponding to each coordinate in the image; take the spatial information as the XY axis, take one of the gray, phase, and polarization parameters as the Z axis as needed to construct a three-dimensional twin light field, or take the gray, phase, and polarization parameters as the Z axis respectively to construct the spatial-gray, spatial-phase, and spatial-polarization information and further construct multiple parallel three-dimensional twin light fields; the three-dimensional twin light field includes multiple scatter points containing spatial information XY and gray, phase, and polarization information Z; S23: Calibrate the reference light field; in the static state of the measured structure, collect multiple frames of twin speckle images to construct an initial three-dimensional twin light field as a reference.

4. The microstructure thermodynamic multi-parameter integrated dynamic precision measurement method according to claim 1, characterized in that: In step three, the measured microstructure is installed on a high-speed milling experiment platform to simulate the working condition of the milling process, so that the measured structure generates multi-parameter changes including temperature, stress, vibration, and phase; A preset acquisition frequency is used to obtain dynamic twin speckle images; a three-dimensional twin light field corresponding to each twin speckle image is constructed for multi-parameter analysis.

5. The microstructure thermodynamic multi-parameter integrated dynamic precision measurement method according to claim 1, characterized in that: Step four specifically includes: S41: Use a high-frequency filtering algorithm to extract high-frequency fluctuation information from the dynamically changing three-dimensional twin light field, which corresponds to the vibration parameter of the measured structure; S42: Segmentally analyze the low-frequency information: the gradual disturbance of the twin light field corresponds to the temperature sensitive area, the gray value change is obtained from the dynamically changing three-dimensional twin light field, and based on the preset calibration relationship between the light field change and the temperature, the temperature value at the corresponding time is obtained; the structural disturbance of the twin light field corresponds to the stress sensitive area, the change of the scatter point aggregation degree of the dynamically changing three-dimensional twin light field is obtained, and the stress value is derived combined with the material mechanics parameters; S43: Align the analysis results of the temperature, stress, and vibration parameters in time through the time stamp recorded by the image acquisition card to obtain multi-parameter data consistent in time.

6. The microstructure thermodynamic multi-parameter integrated dynamic precision measurement method according to claim 5, characterized in that: The high-frequency fluctuation information in step S41 includes high-frequency fluctuation frequency and amplitude, and instantaneous change rate of light field gray value, phase, and polarization information; the vibration speed and amplitude of the structure are determined through the high-frequency fluctuation information.

7. The microstructure thermodynamic multi-parameter integrated dynamic precision measurement method according to claim 5, characterized in that: In step S42, the change of the scatter point aggregation degree in the dynamically changing three-dimensional twin light field is combined with the material mechanics parameters to derive the stress value, specifically: by analyzing the structural change characteristics of the disturbed twin light field, the mechanical properties of the measured structure are fused, and the deformation of the measured object is coded, wherein the structural change characteristics include twist, fractal characteristics, and change of geometric characteristic parameters.

8. The microstructure thermodynamic multi-parameter integrated dynamic precision measurement method according to claim 1, characterized in that: It also includes step five: parameter optimization; compare the temperature, stress, and vibration parameters obtained in step four with the actual parameters, adjust the beam splitting ratio of the beam splitter, the spatial parameters of the receiving optical fiber, and the filtering threshold to improve the measurement accuracy and dynamic response speed.

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