A method and device for measuring lateral vibration of diamond wire saw

Abstract

The present invention provides a method and device for measuring the transverse vibration of a diamond wire saw. A given vibration excitation signal is applied to two supporting ends of a diamond wire saw on a vibration measurement stand by an exciter, an industrial camera is used to collect images at each moment during the transverse vibration of the diamond wire saw, the collected images are preprocessed and traversed to obtain information of each pixel, and the inner diameter boundary and center coordinates of the wire saw are obtained by multiple least squares linear fitting, and finally a transverse vibration displacement curve of the diamond wire saw is obtained. The vibration measurement device can be used to study the influence of the vibration source intensity of the supporting excitation at both ends of the diamond wire saw, the saw wire specifications and the installation parameters on the transverse vibration displacement of the diamond wire saw, and then understand the influence of the vibration source intensity on the sawing seam loss and the slicing quality and the critical state of the saw wire adhesion, and at the same time, the transverse vibration of the diamond wire saw can be accurately measured during the working process, so as to make up for the defect of large error in the traditional transverse vibration measurement method of the diamond wire saw.

Description

Technical Field

[0001] The invention relates to the technical field of vibration measurement, and in particular to a method and a device for measuring the lateral vibration of a diamond wire saw. Background Art

[0002] Diamond wire saws are widely used in the slicing of brittle materials such as silicon, silicon carbide, and sapphire. They have the advantages of high cutting efficiency, good slicing quality, low environmental pollution, and low production costs. Diamond wire saw slicing is the first processing step, and the quality of its slicing has an important impact on subsequent processes and processing costs.

[0003] During the diamond wire saw slicing process, the lateral vibration of the diamond wire saw is a key factor affecting the processing quality. Small vibrations will affect the surface roughness of the slice processing and reduce the surface quality. When the vibration is too large, it will expand the saw seam loss during the sawing process, and even increase the surface crack damage of the slice, resulting in material breakage, affecting the further thinning of the slice thickness. In addition, the lateral vibration displacement of the wire saw will instantly reduce the wire saw spacing, which may further lead to a more significant liquid bridge effect between the wire saws, causing the wire saw to adhere, restricting the thinning of the slice. Therefore, in order to further reduce the kerf loss and slice thickness, increase the slice output rate and reduce its manufacturing cost, it is necessary to study the influence of the excitation at both ends of the wire saw on the lateral vibration of the diamond wire saw, and accordingly improve the vibration state of the machine tool and the manufacturing accuracy of the winding guide wheel, control the vibration source at both ends of the saw wire within a reasonable range, and reduce the influence of the lateral vibration of the diamond wire saw on the kerf loss, slice quality and the critical state of wire saw adhesion, thereby improving the processing quality and efficiency and meeting market demand. Summary of the invention

[0004] In order to solve the problems existing in the background technology, the present invention proposes a method and device for measuring the lateral vibration of a diamond wire saw based on visual detection. Since the diameter of the diamond wire saw is sub-millimeter, its vibration state can generally only be measured by a non-contact vibrometer, such as a laser Doppler vibrometer. However, since the surface of the diamond wire saw has irregular raised abrasive particles, the measurement result of the laser vibrometer will have a large error. Measurement based on visual detection can effectively avoid such errors, and the results are more accurate. The specific scheme is as follows:

[0005] A device for measuring the lateral vibration of a diamond wire saw comprises a measuring platform, on which two guide rails are mounted in parallel, two vibration platforms are slidably mounted on one of the guide rails, both vibration platforms are provided with a vibrator, and two micro-motion platforms are slidably mounted on the other guide rail, the two micro-motion platforms respectively support two ends of the diamond wire saw, the output end of the vibrator contacts the diamond wire saw mounted on the micro-motion platform, an industrial camera for collecting images is disposed above the two micro-motion platforms, and a position of interest of the diamond wire saw is located within the field of view of the industrial camera.

[0006] Preferably, a light source is provided on one side of the industrial camera.

[0007] Preferably, the diamond wire saw is installed on a micro-motion platform through a vibration measuring stand, one end of the diamond wire saw is fixed on the vibration measuring stand, and the other end of the diamond wire saw is movably mounted on the vibration measuring stand. The micro-motion platform is a two-dimensional micro-motion platform, and the micro-motion platform cooperates with the guide rail to drive the diamond wire saw to have three position adjustment directions in space.

[0008] Preferably, one end of the diamond wire saw movably mounted on the vibration measurement stand is connected to a weight, and the weights are multiple with different weights.

[0009] A method for measuring lateral vibration of a diamond wire saw comprises the following steps:

[0010] Step 1, respectively install the two ends of the diamond wire saw to be tested on the vibration measurement stand, and adjust the span and tension of the diamond wire saw on the vibration measurement stand according to the actual span and tension of the two ends of the diamond wire saw on the actual processing machine tool;

[0011] Step 2: Set the light source according to the actual situation, and collect the initial image of the interested position of the diamond wire saw through the industrial camera, and the diamond wire saw is placed horizontally in the image;

[0012] Step 3, obtaining actual vibration signals of the diamond wire saw at both ends of the wire saw on the actual processing machine tool, setting the working parameters of the exciter according to the actual situation, and applying vibration excitation to the supporting positions at both ends of the diamond wire saw through the exciter;

[0013] Step 4, using an industrial camera to collect vibration images of the diamond wire saw at different times at the location of interest;

[0014] Step 5: Preprocess the collected image to obtain the wire saw contour image and the number of image columns N. col and the number of rows N raw ;

[0015] Step 6, traverse the image to obtain the outer contour of the diamond wire saw, and then obtain the inner diameter boundary of the diamond wire saw through multiple least squares linear fitting, and obtain the center position of the wire saw in the image based on this;

[0016] Step 7: According to the deviation of the wire saw center from the initial position at different times, the lateral vibration displacement of the wire saw is obtained, and the characteristic value of the wire saw vibration state is calculated to complete the lateral vibration measurement of the diamond wire saw.

[0017] Preferably, step 5 includes the following steps: firstly, bilateral filtering is performed on the image to remove the noise in the image while retaining the edge information of the image, then the image clarity is improved by performing local adaptive histogram equalization on the grayscale image, and finally, Canny edge detection is performed on the image to obtain a wire saw contour line map, and the image gaps are filled using lateral expansion, wherein the number of image columns and rows are N respectively. col and N raw .

[0018] Preferably, step 6 comprises the following steps: ①, firstly, traverse from the top and bottom of the first column of pixels in the image respectively, stop when the pixel value is 255, record the positions of the upper and lower boundary pixel points of the column of pixels, and then traverse each column in the image from left to right in accordance with the above method, and obtain the original vertical coordinates B of the upper and lower outermost boundaries of the diamond wire saw contour line in the image. top and B bot ;

[0019] ② Perform the least squares linear fitting on the upper and lower outermost boundaries of the wire saw contour to obtain the equations of the two lines l top and l bot , the equation is as follows:

[0020] l top (k)=

[0021] l bot (k)=

[0022] Compare the original ordinate and the ordinate on the fitted line in the same column, i.e. the same horizontal coordinate (B top (k) and l top (k) and B bot (k) and l bot (k)), the original ordinate outside the wire saw inner diameter fitting line is replaced by the ordinate on the fitting line, that is, when B top (k) < l top (k), let B top (k) = l top (k), when B bot (k) > l bot (k), let B bot (k) = l bot (k), perform N cyc The linear fitting and replacement are performed to obtain the linear equation of the inner diameter boundary of the wire saw in the image;

[0023] ③. According to the boundary line equation of the inner diameter of the diamond wire saw in the image, calculate the vertical coordinate B of the center of the wire saw center =[B top(N col / 2)+B bot (N col / 2)] / 2.

[0024] Preferably, step 7 includes the following steps: comparing the difference between the vertical coordinate of the wire saw center during the vibration process and the vertical coordinate of the wire saw center at the initial position, and obtaining the diamond wire saw vibration displacement curve C according to the ratio p of the actual size to the pixel. vib (t) = p[B center (t)-B center (0)].

[0025] The present invention has the following beneficial effects: compared with traditional laser vibration measurement, the method and device of the present invention have higher measurement accuracy, and the center position of the saw wire in the image can be obtained through image processing and analysis and calculation, without being affected by the size and distribution of abrasive particles; at the same time, the method and device of the present invention have good applicability, and can measure the vibration of diamond wire saws with any excitation signal, installation parameters and specifications, with small measurement limitations. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is a schematic diagram of the overall structure of the measuring device of the present invention;

[0027] Figure 2 It is a basic flow chart of the measuring method of the present invention;

[0028] Figure 3 The image of the diamond wire saw during vibration is collected by the industrial camera of the present invention;

[0029] Figure 4 The diamond wire saw contour line image obtained by the present invention using Canny edge detection;

[0030] Figure 5 This is the outer contour image of the diamond wire saw obtained by traversing the image in the present invention.

[0031] Numbers in the figure: 1-diamond wire saw, 2-industrial camera, 3-light source, 4-vibrator, 5-micro-motion platform, 6-guide rail, 7-weight, 8-vibration table, 9-measuring platform, 10-vibration measurement stand. DETAILED DESCRIPTION

[0032] In order to make the present invention clearer and more understandable, the technical solution of the present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments. It should be understood that the given embodiment is only one implementation method and does not represent all embodiments.

[0033] It should be understood that the wire saw mentioned in the article is the diamond wire saw 1. The "horizontal" of the diamond wire saw 1 placed horizontally in the image is relative to the image, and the "horizontal" of the diamond wire saw 1 vibrating horizontally is relative to the three-dimensional space, that is, the "horizontal" of the diamond wire saw 1 vibrating horizontally is vertical in the image.

[0034] Combination Figure 1 A diamond wire saw lateral vibration measuring device comprises a measuring platform 9, on which two guide rails 6 are installed, and the two guide rails 6 are arranged in parallel. Two vibration platforms 8 are slidably provided on one of the guide rails 6, and both vibration platforms 8 are provided with a vibrator 4. Two micro-motion platforms 5 are slidably provided on the other guide rail 6, and the two micro-motion platforms 5 respectively support two ends of the diamond wire saw 1, and the output end of the vibrator 4 contacts the diamond wire saw 1 installed on the micro-motion platform 5. An industrial camera 2 for collecting images is provided above the two micro-motion platforms 5, and the position of interest of the diamond wire saw 1 is located within the field of view of the industrial camera 2.

[0035] A light source 3 is provided on one side of the industrial camera 2 , and the light source 3 is used to increase the gray value difference between the diamond wire saw 1 and the background in the collected image, and the light source 3 must ensure that it irradiates the wire saw within the field of view of the industrial camera 2 .

[0036] The diamond wire saw 1 is installed on the micro-motion platform 5 through the vibration measuring stand 10. One end of the diamond wire saw 1 is fixed on the vibration measuring stand 10, and the other end of the diamond wire saw 1 is movably installed on the vibration measuring stand 10. The micro-motion platform 5 is an existing two-dimensional micro-motion platform. The micro-motion platform 5 cooperates with the guide rail 6 to drive the diamond wire saw 1 to have three position adjustment directions in space. The three position directions include the length direction of the diamond wire saw 1, the radial direction of the diamond wire saw 1, and the height direction. The length direction adjustment of the diamond wire saw 1 is achieved by moving the micro-motion platform 5 on the guide rail 6. The micro-motion platform 5 is provided with a rotary rod. By rotating the rotary rod, the micro-motion platform 5 can be moved in micrometer level in the up and down and front and back directions. The movement of the micro-motion platform 5 drives the movement of the vibration measuring stand 10, thereby realizing the fine adjustment of the position of the diamond wire saw 1. The front and back movement of the micro-motion platform 5 is the movement of the diamond wire saw 1 in its radial direction, and the up and down movement of the micro-motion platform 5 is the movement in the height direction.

[0037] One end of the diamond wire saw 1 movably mounted on the vibration measurement stand 10 is connected to a weight 7 , and the weight 7 has a plurality of weights of different weights.

[0038] Combination Figure 1-5 , a method for measuring lateral vibration of a diamond wire saw, comprising the following steps:

[0039] Step 1, respectively install the two ends of the diamond wire saw 1 to be tested on the vibration measurement stand 10, adjust the span and tension of the diamond wire saw 1 on the vibration measurement stand 10 according to the actual span and tension at both ends of the wire saw on the actual processing machine tool, adjust the span of the diamond wire saw 1 by moving the two micro-motion platforms 5 closer to or farther from each other along the guide rail 6, and adjust the tension of the diamond wire saw 1 by applying weights of different weights;

[0040] Step 2, setting the light source 3 according to the actual situation, ensuring that the light source 3 illuminates the wire saw within the camera field of view, and collecting the initial image of the diamond wire saw 1 at the position of interest through the industrial camera 2, and the diamond wire saw 1 is placed horizontally in the image;

[0041] Step 3, obtaining actual vibration signals of the two ends of the diamond wire saw 1 on the actual processing machine tool, setting the working parameters of the exciter 4 according to the actual situation, and applying vibration excitation to the supporting positions at both ends of the diamond wire saw 1 through the exciter 4;

[0042] Step 4, collecting vibration images of the interested position of the diamond wire saw 1 at different times through the industrial camera 2;

[0043] Step 5: Upload the image collected by the industrial camera 2 to the computer, and use the computer to pre-process the collected image to obtain the wire saw contour image and the number of image columns N. col and the number of rows N raw Specifically, the image is first subjected to bilateral filtering to remove the noise in the image while retaining the edge information of the image. Then, the image clarity is improved by performing local adaptive histogram equalization on the grayscale image. Finally, the image is subjected to Canny edge detection to obtain the wire saw contour line map, and the image gaps are filled using lateral expansion, where the number of image columns and rows are N respectively. col and N raw ;

[0044] Step 6, traverse the image to obtain the outer contour of the diamond wire saw, and then obtain the inner diameter boundary of the diamond wire saw through multiple least squares linear fitting, and obtain the center position of the wire saw in the image based on this;

[0045] Specifically, step 6 is as follows: ①, first start traversing from the top and bottom of the first column of pixels in the image, stop when the pixel value is 255, record the positions of the upper and lower boundary pixel points of the column of pixels, the first column of pixels is located on the left side of the image, and then traverse each column in the image from left to right according to the above method to obtain the original vertical coordinates B of the upper and lower outermost boundaries of the diamond wire saw contour line in the image top and B bot , where B top is the ordinate of the outermost upper boundary of the diamond wire saw contour, B botis the ordinate of the outermost lower boundary of the diamond wire saw contour;

[0046] ② Perform the least squares linear fitting on the upper and lower outermost boundaries of the wire saw contour to obtain the equations of the two lines l top and l bot , the equation is as follows:

[0047] l top (k)=

[0048] l bot (k)=

[0049] Compare the original ordinate and the ordinate on the fitted line in the same column, i.e. the same horizontal coordinate (B top (k) and l top (k) and B bot (k) and l bot (k)), the original ordinate outside the wire saw inner diameter fitting line is replaced by the ordinate on the fitting line, that is, when B top (k) < l top (k), let B top (k) = l top (k), when B bot (k) > l bot (k), let B bot (k) = l bot (k) N cyc The linear equation of the inner diameter boundary of the wire saw in the image is obtained by fitting and replacing the linear equation. N cyc is the number of fittings, which will be determined based on experimental conditions.

[0050] ③. According to the boundary line equation of the inner diameter of the diamond wire saw in the image, calculate the vertical coordinate B of the center of the wire saw center =[B top (N col / 2)+B bot (N col / 2)] / 2.

[0051] Step 7: According to the deviation of the wire saw center from the initial position at different times, the lateral vibration displacement of the wire saw is obtained, and the characteristic value of the wire vibration state is calculated. Specifically, the difference between the vertical coordinate of the diamond wire saw center during the vibration process and the vertical coordinate of the wire saw center at the initial position is compared, and the diamond wire saw vibration displacement curve C is obtained according to the ratio p of the actual size to the pixel. vib (t) = p[B center (t)-B center(0)], completing the lateral vibration measurement of diamond wire saw.

[0052] The above embodiments are only to illustrate the basic principles and characteristics of the present invention, but are not limited to the above embodiments. It should be understood that for ordinary technicians in this field, various changes and modifications can be made to the present invention without departing from the spirit and scope of the present invention, and these changes and modifications fall within the scope of the present invention to be protected. The scope of protection of the present invention is defined by the attached claims and their equivalents.

Claims

1. A method for measuring the lateral vibration of a diamond wire saw, characterized in that: The following steps are involved: Step 1, respectively mounting the two ends of the diamond wire saw (1) to be tested on the vibration measuring stand (10), and adjusting the span and tension of the diamond wire saw (1) on the vibration measuring stand (10) according to the actual span and tension at both ends of the diamond wire saw (1) on the actual processing machine tool; Step 2, setting the light source (3) according to the actual situation, collecting the initial image of the interested position of the diamond wire saw (1) through the industrial camera (2), and the diamond wire saw (1) is placed horizontally in the image; Step 3, obtaining actual vibration signals of the two ends of the diamond wire saw (1) on the actual processing machine tool, setting the working parameters of the exciter (4) according to the actual situation, and applying vibration excitation to the supporting positions at both ends of the diamond wire saw (1) through the exciter (4); Step 4, collecting vibration images of the interested position of the diamond wire saw (1) at different times by means of the industrial camera (2); Step 5: Preprocess the collected image to obtain the wire saw contour image and the number of image columns N. col and the number of rows N raw ; Step 6, traverse the image to obtain the outer contour of the diamond wire saw (1), then obtain the inner diameter boundary of the diamond wire saw (1) through multiple least squares linear fitting, and obtain the center position of the wire saw in the image based on this; Step 7: According to the deviation of the wire saw center from the initial position at different times, the lateral vibration displacement of the wire saw is obtained, and the characteristic value of the wire saw vibration state is calculated to complete the lateral vibration measurement of the diamond wire saw (1).

2. The method for measuring lateral vibration of a diamond wire saw according to claim 1, characterized in that: The step 5 comprises the following steps: firstly, bilateral filtering is performed on the image to remove the noise in the image while retaining the edge information of the image; then, the image clarity is improved by performing local adaptive histogram equalization on the grayscale image; finally, Canny edge detection is performed on the image to obtain a wire saw contour line map, and the image gaps are filled using lateral expansion, where the number of image columns and rows are N respectively. col and N raw .

3. The method for measuring lateral vibration of a diamond wire saw according to claim 1, characterized in that: The step 6 comprises the following steps: ①, firstly, traverse from the top and bottom of the first column of pixels in the image respectively, stop when the pixel value is 255, record the positions of the upper and lower boundary pixel points of the column of pixels, and then traverse each column in the image from left to right in accordance with the above method, and obtain the original vertical coordinates B of the upper and lower outermost boundaries of the contour line of the diamond wire saw (1) in the image; top and B bot ; ② Perform the least squares linear fitting on the upper and lower outermost boundaries of the wire saw contour to obtain the equations of the two lines l top and l bot , the equation is as follows: Compare the original ordinate and the ordinate on the fitting line in the same column, that is, the same horizontal coordinate, and replace the original ordinate outside the wire saw inner diameter fitting line with the ordinate on the fitting line, that is, when B top (k) <l top (k), let B top (k) = l top (k), when B bot (k)>l bot (k), let B bot (k) = l bot (k), perform N cyc The linear equation of the inner diameter boundary of the wire saw in the image is obtained by fitting and replacing the N cyc is an integer; ③. According to the boundary line equation of the inner diameter of the diamond wire saw (1) in the image, calculate the vertical coordinate B of the center of the wire saw center =[B top (N col / 2)+B bot (N col / 2)] / 2.

4. The method for measuring lateral vibration of a diamond wire saw according to claim 1, characterized in that: The step 7 comprises the following steps: comparing the difference between the vertical coordinate of the wire saw center during the vibration process and the vertical coordinate of the wire saw center at the initial position, and obtaining the vibration displacement curve C of the diamond wire saw (1) according to the ratio p of the actual size to the pixel. vib (t) = p[B center (t)-B center (0)].

5. A diamond wire saw lateral vibration measuring device, used for implementing the diamond wire saw lateral vibration measuring method according to claim 1, characterized in that: The measuring platform (9) comprises two guide rails (6) installed on the measuring platform (9). The two guide rails (6) are arranged in parallel. Two vibration platforms (8) are slidably arranged on one of the guide rails (6). Both vibration platforms (8) are provided with a vibrator (4). Two micro-motion platforms (5) are slidably arranged on the other guide rail (6). The two micro-motion platforms (5) respectively support two ends of a diamond wire saw (1). The output end of the vibrator (4) contacts the diamond wire saw (1) installed on the micro-motion platform (5). An industrial camera (2) for collecting images is arranged above the two micro-motion platforms (5). The position of interest of the diamond wire saw (1) is located within the field of view of the industrial camera (2).

6. A diamond wire saw lateral vibration measuring device according to claim 5, characterized in that: A light source (3) is provided on one side of the industrial camera (2).

7. The device for measuring lateral vibration of a diamond wire saw according to claim 5, characterized in that: The diamond wire saw (1) is mounted on a micro-motion platform (5) via a vibration measuring stand (10); one end of the diamond wire saw (1) is fixed on the vibration measuring stand (10); the other end of the diamond wire saw (1) is movably mounted on the vibration measuring stand (10); the micro-motion platform (5) is a two-dimensional micro-motion platform; the micro-motion platform (5) cooperates with a guide rail (6) to drive the diamond wire saw (1) to have three position adjustment directions in space.

8. A diamond wire saw lateral vibration measuring device according to claim 7, characterized in that: One end of the diamond wire saw (1) movably mounted on the vibration measurement stand (10) is connected to a weight (7), and the weight (7) has a plurality of weights of different weights.

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