Fretting wear process evolution in-situ detection device and method

Abstract

The invention relates to a fretting wear process evolution in-situ detection device which comprises an air flotation vibration isolation platform, a fretting friction testing machine, an industrial electron microscope group and a metallographic microscope group are arranged on the upper surface of the air flotation vibration isolation platform, the fretting friction testing machine comprises an upper clamp and a lower clamp, an upper sample is arranged in the upper clamp, and a lower sample is arranged in the lower clamp. A lower test sample is arranged in the lower clamp, the upper clamp can drive the upper test sample to move to be in contact with the lower test sample, and the fretting friction testing machine further comprises a three-way translation table for microcosmically adjusting the lower test sample. According to the invention, the upper clamp is arranged to clamp the upper sample, the lower clamp is arranged to clamp the lower sample, and the three-way translation table is arranged to carry out microscopic adjustment on the lower sample, so that the upper sample and the lower sample are rubbed so as to evolve the abrasion process of the upper sample and the lower sample; and the mechanism and the rule of fretting wear can be conveniently and deeply researched.

Description

Technical Field

[0001] The present invention relates to the technical field of fretting wear detection equipment, and in particular to an in-situ detection device and method for fretting wear process evolution. Background Art

[0002] Fretting wear refers to the extremely small amplitude relative movement between contact surfaces under the action of alternating loads such as mechanical vibration and fatigue load, which will cause friction and wear between contact surfaces, resulting in material loss and other consequences. This phenomenon is common in many industrial fields such as machinery, aerospace, nuclear reactors, weapon systems, power electronics, etc. There are surface engineering technologies to solve the problem of fretting wear. For example, fretting damage can be mitigated by changing the fretting area, introducing residual compressive stress, reducing the friction coefficient, and increasing the surface hardness. There are also common countermeasures such as structural optimization and lubrication solutions.

[0003] Current fretting wear testing machines often require the wear specimen to be disassembled for analysis. This method is not only time-consuming and labor-intensive, but also unable to monitor the evolution of fretting wear in real time and in situ. In addition, during the disassembly process, the experimental results of the wear specimen may be destroyed, and key information in the wear process cannot be accurately obtained, such as the generation of wear particles, changes in surface morphology, dynamic fluctuations in the friction coefficient, etc., making it difficult to conduct in-depth research on the mechanism and laws of fretting wear, thereby limiting the precise formulation of measures to improve the wear resistance and reliability of components.

[0004] In order to solve the above problems, the present invention proposes an in-situ detection device and method for the evolution of micro-wear process. Summary of the invention

[0005] (1) Technical issues to be solved

[0006] The purpose of the present invention is to overcome the deficiencies of the prior art, meet practical needs, and provide an in-situ detection device and method for the evolution of micro-wear processes to solve the above-mentioned technical problems.

[0007] (2) Technical solution

[0008] In order to achieve the purpose of the present invention, the technical solution adopted by the present invention is:

[0009] An in-situ detection device for the evolution of a micro-motion wear process comprises an air-floating vibration isolation platform, wherein the upper surface of the air-floating vibration isolation platform is respectively provided with a micro-motion friction tester, an industrial electron microscope group and a metallographic microscope group, wherein the micro-motion friction tester comprises an upper fixture and a lower fixture, wherein an upper sample is provided in the upper fixture, wherein a lower sample is provided in the lower fixture, wherein the upper fixture can drive the upper sample to move to a contact state with the lower sample, wherein the micro-motion friction tester further comprises a three-way translation stage for microscopically adjusting the lower sample, wherein the upper surface of the three-way translation stage is fixedly connected with a precision small-sized ultra-thin electric translation stage, and wherein the lower fixture is fixedly connected to the upper surface of the precision small-sized ultra-thin electric translation stage.

[0010] Furthermore, the upper sample is an alumina ceramic ball, and resin is disposed on the outside of the lower sample.

[0011] Furthermore, the micro-friction testing machine also includes a base, the three-way translation stage is fixedly connected to the upper surface of the base, two pads are respectively fixedly connected to the upper surface of the base, the upper surface of the pads is fixedly connected to a bearing seat, a bearing body is arranged in the bearing seat, the inner ring surface of the bearing body is fixedly connected to a rotating shaft, the surface of the rotating shaft is fixedly connected to a first force arm, the end of the first force arm is fixedly connected to a force sensor, the end of the force sensor is fixedly connected to a second force arm, the upper clamp is installed on the second force arm, and a counterweight is arranged on the upper surface of the second force arm.

[0012] Furthermore, a spherical groove cooperating with the alumina ceramic ball is formed on the upper surface of the upper clamp, a pressure cover is provided on the upper clamp, and an arcuate through hole is formed on the lower surface of the pressure cover, and the diameter of the arcuate through hole is smaller than the diameter of the alumina ceramic ball.

[0013] Furthermore, the upper surface of the air-floating vibration isolation platform is fixedly connected to a computer and a control cabinet respectively, the force sensor transmits data to the computer via a data line, and also includes an oil-free silent air compressor sealedly connected to the air-floating vibration isolation platform via an air pipe and an air bag.

[0014] Furthermore, two sliding modules are fixedly connected to the upper surface of the air-floating vibration isolation platform, and the industrial electron microscope group and the metallographic microscope group are respectively installed on the two sliding modules.

[0015] Further, the industrial electron microscope group includes a mounting base fixedly connected to the mobile end of the front-side sliding module. A vertical column is fixedly connected to the upper surface of the mounting base. A retainer is fixedly connected to the surface of the vertical column. A sliding rod is slidably connected to the end of the retainer. An installation frame is fixedly connected to one side of the sliding rod. An electron microscope body is fixedly connected inside the installation frame. A rack is fixedly connected to the side of the sliding rod away from the installation frame. A through hole is formed in the surface of the retainer, and a sleeve is fixedly connected to the inner wall of the through hole. A screw rod is rotatably connected to the inner wall of the sleeve. The screw rod meshes with the rack. Rotating knobs are fixedly connected to both ends of the screw rod.

[0016] Further, the metallographic microscope group includes a connection base fixedly connected to the mobile end of the rear-side sliding module. A vertical rod is fixedly connected to the upper surface of the connection base. A universal swing arm is arranged on the surface of the vertical rod. A metallographic microscope body is installed at the end of the universal swing arm;

[0017] The universal swing arm includes a first horizontal swing arm rotatably connected to the surface of the vertical rod. A second horizontal swing arm is rotatably connected to the upper surface of the first horizontal swing arm. A first short rod is fixedly connected to the upper surface of the second horizontal swing arm. A connecting seat is rotatably connected to the surface of the first short rod. A rotating hole is formed in the surface of the connecting seat, and a second short rod is rotatably connected to the inner wall of the rotating hole. The metallographic microscope body is fixedly connected to the surface of the second short rod. Two limiting rings are respectively fixedly connected to the surface of the vertical rod, and the two limiting rings are respectively located on the upper and lower sides of the first horizontal swing arm. The first horizontal swing arm and the second horizontal swing arm are rotatably connected through a connecting shaft. A first threaded hole is formed in the end of the connecting shaft, and a first fastening knob is threadedly connected to the inner wall of the first threaded hole. Second threaded holes and third threaded holes are respectively formed in the surface of the connecting seat, and a second fastening knob is threadedly connected to the inner wall of the second threaded hole, and a third fastening knob is threadedly connected to the inner wall of the third threaded hole.

[0018] The present invention also discloses a method for in-situ detection of the evolution of the fretting wear process, including the following steps:

[0019] Step 1, set the fretting frequency, amplitude, and number of cycles of the displacement output shaft of the precision small and ultra-thin electric translation stage through a computer in the LabView software. For example, set the total number of cycles to N times, and take pictures of the friction test results at the friction times of N1, N2, and N3 times (N1 < N2 < N3 < N) and zero the precision small and ultra-thin electric translation stage in LabView;

[0020] Step 2, install the lower specimen test material, clamp the lower specimen in the lower fixture, rotate the first force arm to make the upper specimen contact the lower specimen wear material, and place a counterweight on the upper side of the second force arm;

[0021] Step 3: Start the precision small ultra-thin electric translation stage in the computer. When the number of tests reaches N1, the three-way translation stage stops micro-movement, removes the counterweight, and rotates the first force arm to make the upper sample and the lower sample wear material break away from contact;

[0022] Step 4: Adjust the knobs of the front sliding module and the industrial electron microscope group to align the lens of the electron microscope body with the wear debris pits, open the ImageView software for macro photography, start from the edge of the wear debris pits, adjust the knobs and the three-way translation stage to perform depth of field fusion in the Z direction, and then adjust the sliding module to shoot the next position, and obtain clear images of the full depth of field in each area in turn, and then adjust the three-way translation stage to stitch the graphics in the X and Y directions to obtain a complete and clear image. After shooting, adjust the sliding module to return the electron microscope body to its original position;

[0023] Step 5: Adjust the rear sliding module to align the lens of the metallographic microscope body with the wear chip pit, open the ImageView software for microscopic shooting, adjust the universal swing arm to align the lens with the local shooting position of the wear chip pit, adjust the second fastening knob and the three-phase translation stage to perform depth of field fusion in the Z direction, and then adjust the universal swing arm to shoot the next position, and obtain the microscopic morphology of the inside and surrounding wear chips of the pit in turn. After shooting, adjust the sliding module to return the metallographic microscope body to its original position;

[0024] Step 6, after the electron microscope body and the metallographic microscope body are photographed, the first lever arm is rotated to make the upper sample of the alumina ceramic ball contact the wear material of the lower sample, and the wear test is continued;

[0025] Step seven, when the number of tests reaches N2 and N3 respectively, repeat the above steps to photograph the friction results, so as to realize in-situ detection of the evolution of the micro-wear process of the sample.

[0026] (3) Beneficial effects:

[0027] In the present invention, an upper clamp is provided to clamp the upper sample, a lower clamp is provided to clamp the lower sample, and a three-way translation stage is provided to micro-adjust the lower sample, so that friction between the upper sample and the lower sample is made to evolve their wear process, and macroscopic photography is performed by providing an industrial electron microscope group, and microscopic photography is performed by providing a metallographic microscope group, so as to obtain key information in the wear process. Compared with the prior art which always disassembles the sample for analysis, this facilitates in-depth research on the mechanism and law of micro-wear. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 It is a schematic diagram of the three-dimensional structure of the present invention;

[0029] Figure 2 It is a three-dimensional structural schematic diagram of the micro-motion friction testing machine of the present invention;

[0030] Figure 3 For the present invention Figure 2 A schematic diagram of the enlarged structure at A in the middle;

[0031] Figure 4 It is a schematic diagram of the three-dimensional structure of the industrial electron microscope set of the present invention;

[0032] Figure 5 is a schematic cross-sectional view of the fixing device of the present invention;

[0033] Figure 6 For the present invention Figure 5 A schematic diagram of the enlarged structure at B in the middle;

[0034] Figure 7 It is a schematic diagram of the three-dimensional structure of the metallographic microscope set of the present invention.

[0035] The reference numerals are as follows:

[0036] 1. Air-floating vibration isolation platform; 2. Micro-motion friction tester; 201. Upper fixture; 202. Lower fixture; 203. Upper sample; 204. Lower sample; 205. Three-way translation stage; 206. Base; 207. Pad; 208. Bearing seat; 209. Bearing body; 210. Rotating shaft; 211. First force arm; 212. Force sensor; 213. Second force arm; 215. Gland; 216. Precision small ultra-thin electric translation stage; 3. Industrial electron microscope group; 301. Mounting seat; 302. Column; 303. Retainer; 304. Slide bar; 305. Mounting frame; 306. Electronic display Microscope body; 307, rack; 308, sleeve; 309, screw; 310, rotating knob; 4, metallographic microscope group; 401, connecting seat; 402, vertical pole; 403, universal swing arm; 4031, first lateral swing arm; 4032, second lateral swing arm; 4033, first short rod; 4034, connecting seat; 4035, second short rod; 4036, limiting ring; 4037, first fastening knob; 4038, second fastening knob; 4039, third fastening knob; 404, metallographic microscope body; 5, computer; 6, control cabinet; 7, oil-free silent air compressor; 8, sliding module. DETAILED DESCRIPTION

[0037] The following is combined with Figure 1-7 The present invention is further described with examples:

[0038] like Figure 1-7As shown, an in-situ detection device for the evolution of micro-motion wear process includes an air-floating vibration isolation platform 1, and the upper surface of the air-floating vibration isolation platform 1 is respectively provided with a micro-motion friction tester 2, an industrial electron microscope group 3 and a metallographic microscope group 4, the micro-motion friction tester 2 includes an upper fixture 201 and a lower fixture 202, an upper sample 203 is arranged in the upper fixture 201, and a lower sample 204 is arranged in the lower fixture 202, the upper fixture 201 can drive the upper sample 203 to move to a contact state with the lower sample 204, the micro-motion friction tester 2 also includes a three-way translation stage 205 for micro-adjusting the lower sample 204, the upper surface of the three-way translation stage 205 is fixedly connected with a precision small ultra-thin electric translation stage 216, and the lower fixture 202 is fixedly connected to the upper surface of the precision small ultra-thin electric translation stage 216.

[0039] Specifically, in the present invention, the upper sample 203 is clamped by the upper clamp 201, the lower sample 204 is clamped by the lower clamp 202, and the lower sample 204 is micro-adjusted by the three-way translation stage 205, so that the upper sample 203 and the lower sample 204 are rubbed to evolve their wear process, and the macroscopic photography is performed by the industrial electron microscope group 3, and the microscopic photography is performed by the metallographic microscope group 4, so as to obtain key information in the wear process. Compared with the prior art, the sample is always disassembled for analysis, which is convenient for in-depth research. The mechanism and law of micro-motion wear, wherein the three-way translation stage 205 is composed of an X-axis translation stage, a Y-axis translation stage and a Z-axis vertical lifting stage, which are installed on the upper surface of the base 206, and are electrically controlled to adjust their respective adjustment knobs to achieve the movement of the lower fixture 202 in the three directions of XYZ. The air-floating vibration isolation platform 1 is fixed on the base ground. During the experiment, due to people's walking and touching the test bench, the experimental device will shake, affecting the shooting effect. The air-floating vibration isolation platform 1 can effectively avoid the shaking of the lens and maintain the stability of the experimental device.

[0040] The upper sample 203 is an alumina ceramic ball, and the outer portion of the lower sample 204 is provided with resin.

[0041] The micro-motion friction testing machine 2 also includes a base 206, a three-way translation stage 205 is fixedly connected to the upper surface of the base 206, two cushion blocks 207 are fixedly connected to the upper surface of the base 206, a bearing seat 208 is fixedly connected to the upper surface of the cushion block 207, a bearing seat 208 is arranged in the bearing seat 208, a bearing body 209 is fixedly connected to the inner ring surface of the bearing body 209 with a rotating shaft 210, a first force arm 211 is fixedly connected to the surface of the rotating shaft 210, a force sensor 212 is fixedly connected to the end of the first force arm 211, a second force arm 213 is fixedly connected to the end of the force sensor 212, an upper fixture 201 is installed on the second force arm 213, a counterweight is arranged on the upper surface of the second force arm 213, and the cooperation of the bearing seat 208, the bearing body 209 and the rotating shaft 210 facilitates the rotation of the first force arm 211 and the second force arm 213, and facilitates the contact between the upper test and the lower sample 204.

[0042] The upper surface of the upper clamp 201 is provided with a spherical groove that cooperates with the alumina ceramic ball. The upper clamp 201 is provided with a pressure cover 215. The lower surface of the pressure cover 215 is provided with an arc-shaped through hole. The diameter of the arc-shaped through hole is smaller than the diameter of the alumina ceramic ball, which is used to ensure that the alumina ceramic ball is exposed at an appropriate height.

[0043] The upper surface of the air-floating vibration isolation platform 1 is fixedly connected with a computer 5 and a control cabinet 6 respectively. The force sensor 212 transmits data to the computer 5 through a data cable. It also includes an oil-free silent air compressor 7 that is sealed and connected to the air-floating vibration isolation platform 1 through an air pipe and an air bag. The computer 5 sets the micro-motion frequency, amplitude, and number of cycles of the displacement output shaft of the precision small ultra-thin electric translation stage 216 through LabVIEW software and controls its start and stop. The computer 5 shoots the metallographic microscope group 4 and the industrial electron microscope group 3 through ImageVIEW software and completes depth of field fusion and image stitching operations, and controls the start and stop of the air-floating vibration isolation platform 1 through the control cabinet 6.

[0044] Two sliding modules 8 are fixedly connected to the upper surface of the air-floating vibration isolation platform 1, and the industrial electron microscope and the metallographic microscope are respectively installed on the two sliding modules 8. The sliding module 8 is composed of a driving motor, a linear slide rail, a coupling, and a motor mounting seat 301. The driving motor is installed on one side of the motor mounting seat 301 and is connected to the linear slide rail through a coupling. The sliding module 8 is used to support the industrial electron microscope group 3 and the metallographic microscope group 4 so that the overall translation in the X direction can be achieved.

[0045] The industrial electron microscope group 3 includes a mounting seat 301 fixedly connected to the moving end of the front sliding module 8, the upper surface of the mounting seat 301 is fixedly connected to a column 302, the surface of the column 302 is fixedly connected to a retainer 303, the end of the retainer 303 is slidably connected to a slide bar 304, one side of the slide bar 304 is fixedly connected to a mounting frame 305, the mounting frame 305 is fixedly connected to an electron microscope body 306, the side of the slide bar 304 away from the mounting frame 305 is fixedly connected to a rack 307, and the retainer 303 is slidably connected to a slide bar 304. A through hole is provided on the surface of 03, and a sleeve 308 is fixedly connected to the inner wall of the through hole, a screw 309 is rotatably connected to the inner wall of the sleeve 308, the screw 309 is meshed with the rack 307, and both ends of the screw 309 are fixedly connected to a rotating knob 310. The industrial electron microscope can be moved in the X and Z directions through the sliding module 8 and the rotating knob 310 to capture images at different positions and different focal points, and the shooting information is transmitted to the computer 5 through an external data line to prepare for depth of field synthesis and image stitching to obtain images.

[0046] The metallographic microscope group 4 includes a connecting seat 401 fixedly connected to the movable end of the rear sliding module 8, and a vertical rod 402 is fixedly connected to the upper surface of the connecting seat 401. A universal swing arm 403 is provided on the surface of the vertical rod 402. A metallographic microscope body 404 is installed at the end of the universal swing arm 403. A CCD camera is installed on the upper end of the radial microscope body, and the shooting information is transmitted to the computer 5 via a data cable.

[0047] The universal swing arm 403 includes a first lateral swing arm 4031 rotatably connected to the surface of the vertical pole 402, the upper surface of the first lateral swing arm 4031 is rotatably connected to the second lateral swing arm 4032, the upper surface of the second lateral swing arm 4032 is fixedly connected to the first short rod 4033, the surface of the first short rod 4033 is rotatably connected to the connecting seat 4034, the surface of the connecting seat 4034 is provided with a rotating hole, and the inner wall of the rotating hole is rotatably connected to the second short rod 4035, the metallographic microscope body 404 is fixedly connected to the surface of the second short rod 4035, and the surfaces of the vertical pole 402 are respectively fixed. There are two limit rings 4036 fixedly connected, and the two limit rings 4036 are respectively located on the upper and lower sides of the first lateral swing arm 4031. The first lateral swing arm 4031 and the second lateral swing arm 4032 are rotatably connected through a connecting shaft. A first threaded hole is provided at the end of the connecting shaft, and a first tightening knob 4037 is threadedly connected to the inner wall of the first threaded hole. A second threaded hole and a third threaded hole are respectively provided on the surface of the connecting seat 4034, and a second tightening knob 4038 is threadedly connected to the inner wall of the second threaded hole, and a third tightening knob 4039 is threadedly connected to the inner wall of the third threaded hole.

[0048] The present invention also discloses an in-situ detection method for the evolution of fretting wear process, comprising the following steps:

[0049] Step 1: Set the micro-motion frequency, amplitude, and number of cycles of the displacement output shaft of the precision small and ultra-thin electric translation stage 216 in the LabView software through the computer 5. For example, set the total number of cycles to N times, and take pictures of the friction test results at the friction times of N1, N2, and N3 times respectively (N1 < N2 < N3 < N), and zero the precision small and ultra-thin electric translation stage 216 in LabView.

[0050] Step 2: Install the experimental material of the lower specimen 204, clamp the lower specimen 204 in the lower fixture 202, rotate the first lever arm 211 to make the upper specimen 203 contact the worn material of the lower specimen 204, and place a counterweight above the second lever arm 213.

[0051] Step 3: Start the precision small and ultra-thin electric translation stage 216 in the computer 5. When the number of test times reaches N1 times, the three-axis translation stage 205 stops micro-motion, remove the counterweight, and rotate the first lever arm 211 to make the upper specimen 203 separate from the worn material of the lower specimen 204.

[0052] Step 4: Adjust the rotation knob 310 of the front sliding module 8 and the industrial electron microscope group 3 to align the lens of the electron microscope body 306 with the wear debris and wear pits. Open the ImageView software for macroscopic photography. Starting from the outermost edge position of the wear debris and wear pits, adjust the rotation knob 310 and the three-axis translation stage 205 for depth of field fusion in the Z direction, and then adjust the sliding module 8 to photograph the next position. Sequentially obtain a panoramic image with clear depth of field in each area. Then adjust the three-axis translation stage 205 for graphic stitching in the X and Y directions to obtain a complete and clear image. After the photography is completed, adjust the sliding module 8 to return the electron microscope body 306 to its original position.

[0053] Step 5: Adjust the rear sliding module 8 to align the lens of the metallurgical microscope body 404 with the wear debris and wear pits. Open the ImageView software for microscopic photography. Adjust the universal swing arm 403 to align the lens with the local photography position of the wear debris and wear pits. Adjust the second fastening knob 4038 and the three-phase translation stage for depth of field fusion in the Z direction, and then adjust the universal swing arm 403 to photograph the next position. Sequentially obtain the microscopic morphology of the wear debris inside and around the pits. After the photography is completed, adjust the sliding module 8 to return the metallurgical microscope body 404 to its original position.

[0054] Step 6: After the electron microscope body 306 and the metallurgical microscope body 404 complete the photography, rotate the first lever arm 211 to make the alumina ceramic ball upper specimen 203 contact the worn material of the lower specimen 204, and continue the wear test.

[0055] Step 7: When the number of test times reaches N2 and N3 respectively, repeat the above steps to photograph the friction results, so as to realize the in-situ detection of the evolution of the fretting wear process of the specimen.

[0056] The electron microscope body 306 and the metallographic microscope body 404 use depth of field fusion and image stitching technology to shoot the wear evolution process. In view of the fact that after the friction test, the wear chips are distributed around the wear pits and the overall state is undulating, in order to obtain the wear morphology, the electron microscope body 306 and the metallographic microscope body 404 are respectively used to perform macroscopic and microscopic shooting of the worn surface of the sample. The macro shooting uses depth of field fusion and image stitching technology, and the micro shooting uses depth of field fusion technology. The macro shooting range includes the pits caused by wear and the 3D morphology caused by the accumulated wear chips in the surrounding area, and the micro shooting range includes the microscopic morphology of the inside of the pits or the local wear chips in the surrounding area.

[0057] Depth of field fusion is used in both macro and micro photography. First, the electron microscope body 306 is adjusted to align the lens with the desired object, and then the lower sample 204 is micro-adjusted through the three-way translation stage 205 to achieve the focus of the lens on the grinding chips and pits at different positions in the X, Y, and Z directions, and the relatively clear focused areas in each frame of the image are extracted to form a new full-depth image with clear areas in all areas.

[0058] The real-time depth of field synthesis system based on FPGA architecture first collects images of grinding pits and grinding chips, uses n*n filtering kernel to calculate the standard deviation of the collected images, calculates the average value of the obtained standard deviation, obtains the focus coefficient of the image, and synthesizes a new image. The standard deviation formula is:

[0059]

[0060] N represents the number of pixels n*n, Xi represents the value of each pixel, represents the average value, and SN represents the standard deviation value of the pixel point. The FPGA algorithm compares the focus coefficients of the new image and the previous synthetic image. If the focus coefficient of a certain pixel point in the new image is greater than the focus coefficient of the previous synthetic image, the pixel point of the old image is replaced with the pixel point of the new image, otherwise it is not replaced. The iteration of the new and old image data is controlled to achieve the effect of focusing at different focal lengths.

[0061] Depth of field synthesis can be performed on the original test bench to avoid damage to the test sample, and also save time and cost. And it can be photographed at any time. With different times of wear, the evolution of wear is different. You can take pictures at different times of wear. The shooting equipment is connected to the computer, and the picture effect after depth of field synthesis is directly presented on the computer. Macro shooting depth of field synthesis presents the focus of the whole picture, making the image clearer, including the pits caused by wear and the 3D morphology formed by the accumulated debris around. Micro shooting depth of field synthesis presents the microscopic morphology of the inside of the grinding pit or the surrounding debris, including the appearance, color, and particle size of the debris.

[0062] Image stitching technology is applied to macro shooting, and the full depth images taken are stitched in the X and Y directions to present a complete wear chip image. The image stitching process consists of three parts: image acquisition, image registration, and image synthesis. During the shooting process, multiple images are acquired in the X or Y direction. One image is used as the reference image, and the other images are used as search images. They are moved in an orderly manner in the template until the registration position is found. In the process, the image must be preprocessed, including image correction, image noise suppression, etc. After registration, the images are synthesized to obtain a complete and clear image.

[0063] When using image stitching technology, as the wear device wears the sample, the wear area of ​​the wear debris will gradually increase with the evolution of wear. At this time, a single image cannot accurately and completely present the wear area. If you want to clearly and completely analyze the wear debris and grinding pits, you need to use graphic stitching to stitch images in the X and Y directions respectively.

[0064] According to the color of the wear debris, the features are extracted and the wear mechanism is studied. Different materials produce different colors of wear debris. By studying the color of the wear debris, the material that is worn can be determined, and the mechanism of wear can be further determined. First, a typical wear debris color standard library is established, and based on the color feature extraction of the wear debris, the K-Means clustering algorithm and the minimum distance classification method based on Euclidean distance are used for automatic identification, which provides a method for studying the wear mechanism of the wear debris.

[0065] The K-Means clustering algorithm aggregates data with similar features and then performs iterative operations until the conditions are met. Set the number of iterations M, randomly select the RGB values ​​corresponding to N points in the wear debris image as the initial seed point, calculate the average RGB value as the new seed point, and compare it with the original value. If they are equal, the calculation ends. If they are not equal, it continues to iterate until M times.

[0066] The minimum distance classification method is the most basic classification method. It calculates the distance D between the vector to be identified X and the known category vector, and then classifies the vector X into the category with the smallest D. The specific calculation formula is:

[0067]

[0068] In the formula: R1, G1, B1 are the main color pixel values ​​of the extracted wear chip image; R0, G0, B0 are the color values ​​of the standard wear chip material.

[0069] The main color of the wear debris image extracted according to the formula is compared with the material standard color library to identify the material and determine the worn material. The wear mechanism is studied from the worn material to provide information for the wear evolution process of the experiment.

[0070] Using the box dimension method and the morphological analysis algorithm of MATLAB, based on digital image processing technology, the MATLAB software is used to sharpen and morphologically process the wear debris image to obtain parameters such as the size and shape of the wear debris and abrasive grains. First, preprocess the wear debris image: 1. Image segmentation and grayscale conversion; 2. Noise removal; 3. Morphological modification; 4. Parameter measurement.

[0071] In the MATLAB software, a three-dimensional convex hull generated randomly is used to simulate the abrasive grain. Four random points are generated on the surface of a sphere with a radius of R. The sphere radius R adopts the equivalent diameter of equal area of the abrasive grain. Then, a convex hull is formed by connecting these four random points. The random points are repeatedly generated until the convex hull formed by them is greater than the roundness of the top view of the abrasive grain. The roundness of the top view of the abrasive grain shape is calculated from its two-dimensional image of the top view.

[0072] The microscopic image of the wear debris and abrasive grains can be obtained from the metallographic microscope body. Affected by the smooth upper surface of the specimen, the image background brightness is uneven and the boundary is blurred, increasing the segmentation difficulty. The original microscopic image is sharpened and filtered using the Laplace operator to make the boundary clearer, and the threshold processing method is selected to convert the image into a binary image. Since there are white high-brightness areas between the wear debris and the specimen surface, the gray threshold segmentation is performed by manually setting the threshold (80 < R < 250, 70 < G < 250, 0 < B < 80). The medfilt2 function is used to perform median filtering on the binary image to eliminate small bright spots in the image, optimize the binary image of the abrasive grain, and use the imclose function for closing operation to make the contour line of the wear debris smooth to obtain the final binary image. In the binary image, the size and shape of a region can be characterized by the number and distribution of pixels in the region. Different objects in the image have unique numbers, and the recognition numbers are the same within the same object and completely different between different objects. Therefore, the labeling method can be used to measure the area of the abrasive grain. The bwlabel function is used to achieve labeling, and then the regionprops function is used to measure the attributes of different objects. Then, the measured areas are stored in a vector, and finally, the area and morphology of the abrasive grain are obtained.

[0073] In the box dimension method, for a fractal set graph in a plane, when using different equivalent side lengths of the box, the number of interior points N in the box is different. The calculation formula of the box dimension D1 is as follows:

[0074]

[0075] In the formula P iRepresents the probability that a point in the fractal falls into the i-th box. By using the principle of box dimension, the binary image is gridded and counted, and the data pairs of grid size and corresponding number of covered grids can be obtained. The data points are plotted in a double logarithmic coordinate system, and linear regression analysis is performed to obtain a linear equation, which can explain the uniformity of the distribution of wear debris and abrasive particles.

[0076] The three-dimensional distribution state of the abrasive particles was simulated in three dimensions. A sphere with a radius of R was drawn on the sample plane. After obtaining the shape index of the abrasive particles, a convex hull of a specific size was randomly generated in MATLAB to represent the particle entity. The abrasive particle distribution was drawn on the XOY plane according to the surface area equivalent diameter, roundness and centroid coordinates of the simulation points using the while loop statement, verifying the correctness of the D1 calculation.

[0077] The embodiments of the present invention disclose preferred embodiments, but are not limited thereto. A person skilled in the art can easily understand the spirit of the present invention based on the above embodiments and make different extensions and changes. However, as long as they do not deviate from the spirit of the present invention, they are all within the protection scope of the present invention.

Claims

1. An in-situ detection device for the evolution of micro-motion wear process, comprising an air-floating vibration isolation platform (1), wherein the upper surface of the air-floating vibration isolation platform (1) is respectively provided with a micro-motion friction tester (2), an industrial electron microscope group (3) and a metallographic microscope group (4), wherein: The micro-motion friction tester (2) comprises an upper fixture (201) and a lower fixture (202); an upper sample (203) is arranged in the upper fixture (201); a lower sample (204) is arranged in the lower fixture (202); the upper fixture (201) can drive the upper sample (203) to move to a contact state with the lower sample (204); the micro-motion friction tester (2) also comprises a three-way translation stage (205) for performing micro-adjustments on the lower sample (204); a precision small ultra-thin electric translation stage (216) is fixedly connected to the upper surface of the three-way translation stage (205); and the lower fixture (202) is fixedly connected to the upper surface of the precision small ultra-thin electric translation stage (216).

2. The in-situ detection device for the evolution of fretting wear process according to claim 1, characterized in that: The upper sample (203) is an alumina ceramic ball, and the outer portion of the lower sample (204) is provided with resin.

3. The in-situ detection device for the evolution of fretting wear process according to claim 1, characterized in that: The micro-motion friction testing machine (2) also includes a base (206), the three-way translation stage (205) is fixedly connected to the upper surface of the base (206), the upper surface of the base (206) is respectively fixedly connected to two cushion blocks (207), the upper surface of the cushion blocks (207) is fixedly connected to a bearing seat (208), a bearing body (209) is arranged in the bearing seat (208), the inner ring surface of the bearing body (209) is fixedly connected to a rotating shaft (210), the surface of the rotating shaft (210) is fixedly connected to a first force arm (211), the end of the first force arm (211) is fixedly connected to a force sensor (212), the end of the force sensor (212) is fixedly connected to a second force arm (213), the upper fixture (201) is installed on the second force arm (213), and the upper surface of the second force arm (213) is provided with a counterweight.

4. The in-situ detection device for the evolution of fretting wear process according to claim 3, characterized in that: The upper surface of the upper clamp (201) is provided with a spherical groove that matches the alumina ceramic ball, the upper clamp (201) is provided with a pressure cover (215), and the lower surface of the pressure cover (215) is provided with an arc-shaped through hole, and the diameter of the arc-shaped through hole is smaller than the diameter of the alumina ceramic ball.

5. The in-situ detection device for the evolution of fretting wear process according to claim 3, characterized in that: The upper surface of the air-floating vibration isolation platform (1) is respectively fixedly connected to a computer (5) and a control cabinet (6); the force sensor (212) transmits data to the computer (5) via a data line; and the air-floating vibration isolation platform (1) is sealed with an oil-free silent air compressor (7) via an air pipe and an air bag.

6. The in-situ detection device for the evolution of fretting wear process according to claim 1, characterized in that: Two sliding modules (8) are fixedly connected to the upper surface of the air-floating vibration isolation platform (1), and the industrial electron microscope group (3) and the metallographic microscope group (4) are respectively mounted on the two sliding modules (8).

7. The in-situ detection device for the evolution of fretting wear process according to claim 6, characterized in that: The industrial electron microscope group (3) comprises a mounting seat (301) fixedly connected to the movable end of the sliding module (8) at the front side, the upper surface of the mounting seat (301) is fixedly connected to a column (302), the surface of the column (302) is fixedly connected to a retainer (303), the end of the retainer (303) is slidably connected to a sliding rod (304), one side of the sliding rod (304) is fixedly connected to a mounting frame (305), and the mounting frame (305) is fixedly connected inside. An electron microscope body (306) is connected, a rack (307) is fixedly connected to the side of the slide rod (304) away from the mounting frame (305), a through hole is opened on the surface of the retainer (303), and a sleeve (308) is fixedly connected to the inner wall of the through hole, a screw (309) is rotatably connected to the inner wall of the sleeve (308), the screw (309) is meshed with the rack (307), and both ends of the screw (309) are fixedly connected to rotating knobs (310).

8. The in-situ detection device for the evolution of fretting wear process according to claim 6, characterized in that: The metallographic microscope group (4) comprises a connection seat (401) fixedly connected to the movable end of the sliding module (8) at the rear side, the upper surface of the connection seat (401) is fixedly connected to a vertical rod (402), the surface of the vertical rod (402) is provided with a universal swing arm (403), and the end of the universal swing arm (403) is installed with a metallographic microscope body (404); The universal swing arm (403) comprises a first lateral swing arm (4031) rotatably connected to the surface of the vertical pole (402); the upper surface of the first lateral swing arm (4031) is rotatably connected to the second lateral swing arm (4032); the upper surface of the second lateral swing arm (4032) is fixedly connected to the first short rod (4033); the surface of the first short rod (4033) is rotatably connected to a connecting seat (4034); a rotating hole is provided on the surface of the connecting seat (4034); and the inner wall of the rotating hole is rotatably connected to the second short rod (4035); the metallographic microscope body (404) is fixedly connected to the surface of the second short rod (4035); the vertical pole (402 ) are respectively fixedly connected to the surface of the first lateral swing arm (4031), and the two limiting rings (4036) are respectively located at the upper and lower sides of the first lateral swing arm (4031). The first lateral swing arm (4031) and the second lateral swing arm (4032) are rotatably connected via a connecting shaft. A first threaded hole is provided at the end of the connecting shaft, and a first tightening knob (4037) is threadedly connected to the inner wall of the first threaded hole. A second threaded hole and a third threaded hole are respectively provided on the surface of the connecting seat (4034), and a second tightening knob (4038) is threadedly connected to the inner wall of the second threaded hole, and a third tightening knob (4039) is threadedly connected to the inner wall of the third threaded hole.

9. An in-situ detection method for the evolution of micro-wear process, characterized in that: The following steps are involved: Step 1: Use a computer (5) to set the micro-motion frequency, amplitude, and number of cycles of the displacement output shaft of the precision small and ultra-thin electric translation stage (216) in LabView software. For example, set the total number of cycles to N times, and take pictures of the friction test results at the friction times of N1, N2, and N3 times respectively (N1 < N2 < N3 < N), and zero the precision small and ultra-thin electric translation stage (216) in LabView. Step 2: Install the experimental material of the lower specimen (204), clamp the lower specimen (204) in the lower fixture (202), rotate the first lever arm (211) to make the upper specimen (203) contact the worn material of the lower specimen (204), and place a counterweight above the second lever arm (213). Step 3: Start the precision small and ultra-thin electric translation stage (216) in the computer (5). When the number of tests reaches N1 times, the three-axis translation stage (205) stops micro-motion, remove the counterweight, and rotate the first lever arm (211) to make the upper specimen (203) separate from the worn material of the lower specimen (204). Step 4: Adjust the rotation knob (310) of the front sliding module (8) and the industrial electron microscope group (3) to align the lens of the electron microscope body (306) with the wear debris and wear pits. Open the ImageView software for macroscopic photography. Starting from the outermost edge position of the wear debris and wear pits, adjust the rotation knob (310) and the three-axis translation stage (205) for depth of field fusion in the Z direction, and then adjust the sliding module (8) to photograph the next position. Sequentially obtain a panoramic image with clear depth of field in each area. Then adjust the three-axis translation stage (205) for graphic stitching in the X and Y directions to obtain a complete and clear image. After the photography is completed, adjust the sliding module (8) to return the electron microscope body (306) to its original position. Step 5: Adjust the rear sliding module (8) to align the lens of the metallurgical microscope body (404) with the wear debris and wear pits. Open the ImageView software for microscopic photography. Adjust the universal swing arm (403) to align the lens with the local photography position of the wear debris and wear pits. Adjust the second tightening knob (4038) and the three-phase translation stage (205) for depth of field fusion in the Z direction, and then adjust the universal swing arm (403) to photograph the next position. Sequentially obtain the microscopic morphology of the inside of the pits and the local wear debris around them. After the photography is completed, adjust the sliding module (8) to return the metallurgical microscope body (404) to its original position. Step 6: After the photography of the electron microscope body (306) and the metallurgical microscope body (404) is completed, rotate the first lever arm (211) to make the alumina ceramic ball upper specimen (203) contact the worn material of the lower specimen (204), and continue the wear test. Step 7: When the number of tests reaches N2 and N3 respectively, repeat the above steps to photograph the friction results, so as to realize the in-situ detection of the evolution of the fretting wear process of the specimen.

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