A method for measuring the surface roughness of aluminum alloy die-cast parts for computer graphics cards

Abstract

This application relates to the field of surface roughness measurement technology for die-cast parts, specifically to a method for measuring the surface roughness of aluminum alloy die-cast parts for computer graphics cards. The method includes: determining the reflection intensity based on the difference between the phase value of each point at any angle and the average distribution of phase values ​​at all points on the die-cast part surface, and combining this with the difference between the phase values ​​of any two adjacent points within the neighborhood of each point; determining the high reflection influence degree based on the difference between the reflection intensity of each point at any angle and the extreme distribution of reflection intensity at all points on the die-cast part surface; and measuring the surface roughness of the die-cast part based on the phase correction value and the difference between the phase values ​​at each point at any angle, as well as the angle between the tangent plane of each point and the laser beam. This application aims to improve the accuracy of surface roughness measurement results for aluminum alloy die-cast parts for computer graphics cards.

Description

Technical Field

[0001] This application relates to the field of surface roughness measurement technology for die-cast parts, specifically to a method for measuring the surface roughness of aluminum alloy die-cast parts for computer graphics cards. Background Technology

[0002] The surface roughness of die-cast aluminum alloy components for computer graphics cards has a significant impact on heat dissipation, reliability, and machining accuracy. This is especially true in high-performance graphics cards, where surface finish directly affects thermal conductivity and assembly quality. Therefore, accurately measuring the surface roughness of die-cast aluminum alloy components for graphics cards is a crucial step in ensuring product quality. Currently, traditional contact measurement methods (such as profilometers) have limitations in adapting to complex microstructures and easily damaged surfaces. In contrast, optical non-contact measurement methods (such as laser interferometry) can measure complex curved surfaces with high precision and efficiency, obtaining microscopic roughness parameters and accurately determining the surface roughness of die-cast aluminum alloy components for computer graphics cards.

[0003] In existing technologies, the process of measuring the surface roughness of die-cast aluminum alloy parts for computer graphics cards using laser interferometry involves splitting the laser beam into a reference beam and a test beam. After reflection, the beams merge to produce interference fringes. The phase change of the interference fringes is then used to accurately measure the microscopic height differences on the die-cast surface, thereby calculating the surface roughness. However, the smooth and highly reflective surface of aluminum alloy parts for computer graphics cards causes strong specular reflection when the laser beam irradiates it. This results in the measurement probe receiving excessive light intensity, reducing the contrast of the interference fringes and thus decreasing the accuracy of the surface roughness measurement results for the die-cast aluminum alloy parts for computer graphics cards. Summary of the Invention

[0004] To address the aforementioned technical problems, this application provides a method for measuring the surface roughness of aluminum alloy die-cast parts for computer graphics cards, thereby resolving the existing issues.

[0005] The surface roughness measurement method for aluminum alloy die-cast parts of computer graphics cards disclosed in this application adopts the following technical solution:

[0006] One embodiment of this application provides a method for measuring the surface roughness of aluminum alloy die-cast parts for computer graphics cards, the method comprising the following steps:

[0007] The phase values ​​of various points on the surface of the aluminum alloy die-cast part of the computer graphics card are obtained by using a laser beam at different angles, and the aluminum alloy die-cast part of the computer graphics card is denoted as the die-cast part.

[0008] Based on the difference between the phase value of each point at any angle and the average distribution of the phase values ​​of all points on the surface of the die casting, the phase jump degree of each point at any angle is determined. Combined with the difference between the phase values ​​of any two adjacent points in the neighborhood of each point at any angle, the reflection intensity of each point at any angle is determined.

[0009] Based on the difference between the reflection intensity of each point at any angle and the extreme distribution of reflection intensity of all points on the die-cast surface, the high reflection influence degree of each point at any angle is determined; based on the difference between the high reflection influence degree of each point at any angle and the maximum value of the high reflection influence degree of all points on the die-cast surface, as well as the difference between the phase values ​​of each point at the angles corresponding to the maximum and minimum high reflection influence degree, and combined with the phase values ​​of each point at any angle, the phase correction value of each point at any angle is determined;

[0010] Based on the difference in phase values ​​between each point at different angles, and the distance from each point to the nearest edge of the die-casting part, the interference degree of each point is determined, and combined with the phase correction value, the phase correction value of each point at any angle is determined.

[0011] Based on the phase correction value and the difference between the phase values ​​at each point at any angle, as well as the angle between the tangent plane at each point and the laser beam, the phase reliability at each point at any angle is determined. Combined with the phase correction value, the final phase value at each point is determined, and the surface roughness of the die-cast part is measured.

[0012] Preferably, the phase jump degree of each point at any angle is the difference between the phase value of each point at any angle and the average phase value of all points on the surface of the die casting.

[0013] Preferably, the method for determining the reflection intensity at each point under any given angle is as follows:

[0014] Calculate the difference between the phase values ​​of any two adjacent points in the neighborhood of each point at any angle;

[0015] Calculate the mean of the phase values ​​of any two adjacent points in the neighborhood of each point at any angle, and calculate the ratio of the mean of the phase values ​​to the difference between the phase values. Take the average level of the ratio of all adjacent points in the neighborhood of each point at any angle as the reflection intensity of each point at any angle.

[0016] Preferably, the method for determining the high reflectance influence of each point at any angle is as follows:

[0017] For the reflection intensity at each point under all angles, calculate the range of all reflection intensities;

[0018] The ratio of the reflection intensity of each point at any angle to the range is taken as the high reflection influence degree of each point at any angle.

[0019] Preferably, the expression for the phase correction value of each point at any angle is: X i′ ,j =X i,j -[(G i,j -g j )×ΔX j In the formula, X i ′ ,j X represents the phase correction value of point j at angle i; i,j G represents the phase value of point j at angle i; i,j Indicates the high reflectivity influence of point j at angle i; g j This represents the minimum high reflectivity influence of point j across all angles; ΔX j This represents the difference in phase value between point j at the angles corresponding to the maximum and minimum high reflectivity.

[0020] Preferably, the method for determining the interference degree of each point is as follows:

[0021] Calculate the average value of the phase difference between all pairs of angles for each point, and combine the distance from each point to the nearest edge of the die casting with the average value to obtain the interference degree of each point.

[0022] Preferably, the method for determining the phase correction value of each point at any angle is as follows: In the formula, A i,j B represents the phase correction value of point j at angle i; j β represents the interference level at point j; β represents the preset value.

[0023] Preferably, the expression for the phase reliability of each point at any angle is: In the formula, Z i,j θ represents the phase reliability of point j at angle i; i,j represents the acute angle between the laser beam at point j and the tangent plane at point j at the i-th angle; exp[] represents the exponential function with the natural constant as the base; tan() represents the tangent function.

[0024] Preferably, the expression for the final phase value of each point is: In the formula, P j Z represents the final phase value at point j; i,j A represents the phase reliability of point j at angle i; i,j M represents the phase correction value of point j at angle i; M represents the number of all angles.

[0025] Preferably, the measurement of the surface roughness of the die-cast part includes:

[0026] Calculate the average phase value of each point at all angles, and record it as the average phase value of each point. Use the difference between the final phase value of each point and the average phase value as the input of the phase-height formula, and output the height of each point.

[0027] A rectangular coordinate system is constructed with the lower left corner of the die-cast part surface as the origin. The two-dimensional position coordinates and height of all points are used as input to the point cloud model, and a three-dimensional point cloud is output. The three-dimensional point cloud is then used as input to 3D modeling software to output the three-dimensional morphology of the die-cast part surface. The surface roughness parameters of the die-cast part are calculated based on the three-dimensional morphology and using the arithmetic mean roughness formula.

[0028] This application has at least the following beneficial effects:

[0029] This application uses non-contact laser interferometry to measure the surface roughness of computer graphics cards, achieving high-precision measurement results of the surface roughness of the aluminum alloy die-cast parts of computer graphics cards without causing surface scratches. By acquiring phase information from multiple angles, this application can capture the reflection at different angles at each location, helping to locate areas affected by high reflection on the surface of the aluminum alloy die-cast parts of the computer graphics card. Furthermore, by calculating the difference between the phase values ​​of any two adjacent points in the neighborhood of each point at any angle, the reflection intensity is constructed, which helps to locate high-reflection areas and correct the phase value errors caused by high reflection in these areas, thereby improving the overall measurement accuracy. This application analyzes the extreme values ​​of the reflection intensity at each point under all angles... This application constructs a high-reflection influence level by comparing the reflection intensity at each point under any angle, which helps to identify and process high-reflection areas. Furthermore, by combining the high-reflection influence level and phase value, phase errors caused by high reflection are corrected, improving data accuracy. This application also constructs a phase reliability level by analyzing the phase correction value and the difference between the phase value and the phase value at each point under any angle, as well as the angle between the tangent plane at each point and the laser beam. This allows for the evaluation of the reliability of the measurement results at each angle, helping to select more reliable data for the final phase value calculation. Based on the reliability of each position in laser measurements at various angles, multi-angle phase information fusion can obtain a more accurate final phase value, improving the overall measurement accuracy. This application also compares multi-angle phase information at each position on the surface of the aluminum alloy die-cast part of a computer graphics card, allowing for the selection of reliable and true phase information and the elimination of data significantly affected by reflection interference, thus improving the accuracy of the surface roughness measurement results for the aluminum alloy die-cast part of the computer graphics card. Attached Figure Description

[0030] To more clearly illustrate the technical solutions and advantages in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0031] Figure 1 A flowchart illustrating the steps of a method for measuring the surface roughness of an aluminum alloy die-cast part for a computer graphics card, provided in one embodiment of this application;

[0032] Figure 2 This is a schematic diagram of the measurement of an aluminum alloy die-cast part for a computer graphics card provided in one embodiment of this application;

[0033] Figure 3 This is a schematic diagram of the phase correction value extraction process provided in one embodiment of this application;

[0034] Figure 4 This is a schematic diagram illustrating the final phase value acquisition process provided in one embodiment of this application. Detailed Implementation

[0035] To further illustrate the technical means and effects adopted by this application to achieve the intended purpose of the invention, the following, in conjunction with the accompanying drawings and preferred embodiments, details the specific implementation, structure, features, and effects of a surface roughness measurement method for aluminum alloy die-cast parts of computer graphics cards proposed in this application. In the following description, different "one embodiment" or "another embodiment" do not necessarily refer to the same embodiment. Furthermore, specific features, structures, or characteristics in one or more embodiments can be combined in any suitable form.

[0036] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains.

[0037] The following description, in conjunction with the accompanying drawings, details a specific scheme for measuring the surface roughness of an aluminum alloy die-cast part for a computer graphics card, as provided in this application.

[0038] This application provides a method for measuring the surface roughness of an aluminum alloy die-cast part for a computer graphics card, specifically, the method described below. Please refer to [link to relevant documentation]. Figure 1 The method includes the following steps:

[0039] Step S1: Use a laser beam to obtain the phase value of each point on the surface of the computer graphics card aluminum alloy die casting at different angles.

[0040] For the aluminum alloy die-casting of computer graphics cards, a low-power laser source is selected to reduce reflection interference; therefore, a Michelson interferometer is chosen. The aluminum alloy die-casting of the graphics card is fixed on the sample stage of the interferometer, ensuring no vibration and that the surface is kept clean to avoid affecting the clarity of the interference fringes. The laser power is adjusted to avoid over-saturation, and the laser is split into two beams by a beam splitter. One beam is directed towards the reference mirror, and the other beam is directed towards the surface of the aluminum alloy die-casting of the computer graphics card under test. The background light in the measurement environment is kept low, and a light shield or filter is used to reduce the interference of stray light on the interference pattern.

[0041] The surface structure of the aluminum alloy die-cast part of the computer graphics card is complex, such as the presence of inclined areas. By rotating the sample stage, the phase value of the surface of the aluminum alloy die-cast part of the computer graphics card is collected at different angles. In this embodiment, the rotation angle range of the sample stage is set to cover 0° to 90°, with each rotation being 10°. The implementer can also set it according to the specific situation. This embodiment does not impose any special restrictions.

[0042] For ease of description, the aluminum alloy die-cast parts of computer graphics cards will be referred to as die-cast parts in the following text.

[0043] Preferably, the measurement schematic diagram of the aluminum alloy die-cast part of the computer graphics card provided in this embodiment is as follows: Figure 2 As shown.

[0044] Step S2: Based on the difference between the phase value of each point at any angle and the average phase value of all points on the surface of the die casting, determine the phase jump degree of each point at any angle, and combine the difference between the phase values ​​of any two adjacent points in the neighborhood of each point at any angle to determine the reflection intensity of each point at any angle.

[0045] In the process of measuring the surface roughness of a computer graphics card using laser interferometry, the laser beam is split into a reference beam and a measurement beam. After reflection from the graphics card surface, the two beams merge, resulting in an optical path difference. The phase value of each point on the die-cast surface is determined by the optical path difference between the measurement and reference beams. This optical path difference directly corresponds to the phase difference, which represents the height change at that point on the graphics card. Non-contact laser interferometry offers high accuracy; however, the die-cast surface is made of aluminum alloy. When illuminated by a laser beam, the intensity of reflected light is significantly enhanced, potentially leading to errors in the roughness measurement results. Therefore, to ensure the accuracy of surface roughness measurement, it is necessary to correct for the phase information errors in the highly reflective areas of the die-cast surface caused by the aluminum alloy material.

[0046] S201: Based on the difference between the phase value of each point at any angle and the average phase value of all points on the surface of the die casting, determine the phase jump degree of each point at any angle.

[0047] When a laser measurement beam illuminates a highly reflective area on the surface of a graphics card aluminum casting, the intensity of the reflected light is greatly enhanced, potentially causing a sudden jump in phase information—that is, a drastic change in phase value. This results in discontinuous phase data, making it difficult to accurately reflect the surface height. Therefore, by analyzing the difference between the phase value at any given angle and the average distribution of phase values ​​at all points on the die-cast surface, the phase jump degree at any given angle is determined. This is used to reflect the phase jump at each point. Specifically:

[0048] The difference between the phase value of each point at any angle and the average phase value of all points on the surface of the die casting is taken as the phase jump degree of each point at any angle.

[0049] It should be noted that there are many methods to measure the differences between data. In this embodiment, the difference between the phase value of each point at any angle and the average phase value of all points on the die-cast surface is measured by calculating the absolute value of the difference between the phase value of each point at any angle and the average phase value of all points on the die-cast surface. Implementers may also use other methods that can measure differences, such as ratios. This embodiment does not impose any special restrictions on the selection of methods for measuring differences.

[0050] Specifically, the larger the phase value of the current point on the die-cast surface is compared to the average phase value of all points, the greater the phase jump change at that point, and the greater the phase jump degree of that point. Conversely, the smaller the phase value of the current point is compared to the average phase value of all points, the smaller the phase change and the smaller the phase jump degree.

[0051] S202: Based on the phase jump degree of each point at any angle, and combined with the difference between the phase values ​​of any two adjacent points in the neighborhood of each point at any angle, determine the reflection intensity of each point at any angle.

[0052] Points exhibiting phase jumps in die-cast parts may be high-reflectivity areas. However, since the surface of die-cast parts is not flat and has structural variations such as depressions and protrusions, the phase of laser interferometry is obtained based on the optical path difference. The optical path of the reference beam is fixed, while the optical path of the measuring beam changes in the flat portion and the structurally varied (depression / protrusion) portion of the die-cast part. The optical path difference between these two beams will also change, leading to phase changes. Points with large phase jumps may also be caused by structural variations. Generally, phase changes caused by structure are more continuous, while phase changes caused by high reflectivity are more abrupt. Therefore, based on the characteristic of whether the phase change is continuous, the reflection intensity at each point at any angle is determined as follows:

[0053] Each point is used as the center to divide the neighborhood W, where the value of the neighborhood W is set manually. In this embodiment, the value of W is 5. The implementer can also set it according to the specific situation. This embodiment does not impose any special restrictions.

[0054] Furthermore, calculate the difference between the phase values ​​of any two adjacent points in the neighborhood of each point at any angle;

[0055] It should be noted that there are many commonly used methods for measuring the differences between data. In this embodiment, the difference between the phase values ​​of any two adjacent points in the neighborhood of each point at any angle is measured by calculating the absolute value of the difference between the phase values ​​of any two adjacent points in the neighborhood of each point at any angle. Implementers may also use other methods such as ratios to measure differences. This embodiment does not impose any special restrictions on the selection of methods for measuring the differences between data.

[0056] Furthermore, the mean value of the phase values ​​of any two adjacent points in the neighborhood of each point at any angle is calculated, and the ratio of the mean value of the phase values ​​to the difference between the phase values ​​is calculated. The average level of the ratio of all adjacent points in the neighborhood of each point at any angle is taken as the reflection intensity of each point at any angle.

[0057] It should be noted that there are many methods to measure the average level of a set of data. In this embodiment, the average level of the ratio of all adjacent points in the neighborhood of each point at any angle is measured. Implementers may also use other methods to measure the average level of data, such as the geometric mean. This embodiment does not impose any special restrictions on the selection of methods to measure the average level of data.

[0058] Furthermore, based on the reflection intensity at any point under any electrical angle, it can be understood that if the difference in phase value between two adjacent points in the neighborhood of the current point on the die-cast surface is smaller, it indicates that the area where that point is located is more likely to be a high-reflection area. The phase change is a consistent jump, while the structural point area has a continuous phase change, so the reflection intensity of that point is greater, and it is more likely to be a high-reflection area. At the same time, if the jump degree of all points in the neighborhood of the current point is higher, the reflection intensity of that point is greater. Conversely, if the difference in phase value between two adjacent points in the neighborhood of the current point on the die-cast surface is greater, it indicates that the area where that point is located is less likely to be a high-reflection area. The phase change jump is inconsistent, that is, the phase change of the structural point area is discontinuous, so the reflection intensity of that point is smaller, and it is less likely to be a high-reflection area. At the same time, if the jump degree of all points in the neighborhood of the current point is lower, the reflection intensity of that point is smaller.

[0059] Step S3: Based on the difference between the reflection intensity of each point at any angle and the extreme distribution of reflection intensity of all points on the die-cast surface, determine the high reflection influence of each point at any angle; based on the difference between the high reflection influence of each point at any angle and the minimum high reflection influence of all points on the die-cast surface, and the difference between the phase values ​​of each point at the angles corresponding to the maximum and minimum high reflection influence, and in combination with the phase values ​​of each point at any angle, determine the phase correction value of each point at any angle.

[0060] Points with higher reflection intensity are more likely to be located in high-reflection areas on the die-cast part surface. In multi-angle laser interferometry measurements, incident light at different angles in high-reflection areas will cause significantly different reflection patterns, with the phase value changing with the angle. By analyzing the measurement information of each point at different angles, the phase is corrected. Specifically:

[0061] The reflectivity of each point on the surface of the die-cast aluminum alloy varies at different angles, and different laser irradiation angles will also produce different phase values. Therefore, based on the difference between the reflection intensity at each point at any angle and the extreme distribution of reflection intensity at all points on the die-cast surface, the high reflectivity influence at each point at any angle is determined to characterize the impact of high reflectivity on phase measurement. Specifically:

[0062] For the reflection intensity at each point under all angles, calculate the range of all reflection intensities;

[0063] It should be noted that each point has only one phase value at each angle, so the range here is the range of phase values ​​at all angles for each phase point.

[0064] Furthermore, the ratio of the reflection intensity of each point at any angle to the range is taken as the high reflection influence degree of each point at any angle.

[0065] Based on the influence of high reflection at any given angle, it can be understood that if the ratio of the reflection intensity of a point on the surface of the die-casting to the range of all reflection intensities is larger at the current angle, then the influence of high reflection at that point is greater, indicating that the point is more affected by high reflection at the current angle; conversely, if the ratio of the reflection intensity of a point on the surface of the die-casting to the range of all reflection intensities is smaller at the current angle, then the influence of high reflection at that point is smaller, indicating that the point is less affected by high reflection at the current angle.

[0066] Furthermore, based on the difference between the high reflectivity influence of each point at any angle and the minimum high reflectivity influence of all points on the die-cast surface, and the difference between the phase values ​​of each point at the angles corresponding to the maximum and minimum high reflectivity influence, and in combination with the phase values ​​of each point at any angle, the phase correction value of each point at any angle is determined, specifically as follows:

[0067] Phase correction value X at point j under angle i i ′ ,j The expression is: X i ′ ,j =X i,j -[(G i,j -g j )×ΔX j In the formula, X i,j G represents the phase value of point j at angle i; i,j Indicates the high reflectivity influence of point j at angle i; g j This represents the minimum high reflectivity influence of point j across all angles; ΔX j This represents the difference in phase value between point j at the angles corresponding to the maximum and minimum high reflectivity.

[0068] Based on the phase correction values ​​of each point at any angle, it can be understood that the smaller the difference between the high reflectivity of the current point at the current angle and the minimum high reflectivity of the current point at all angles, and the smaller the difference between the phase values ​​of the current point at the angles corresponding to the maximum and minimum high reflectivity, the less the phase value needs to be modified. Conversely, the larger the difference between the high reflectivity of the current point at the current angle and the minimum high reflectivity of the current point at all angles, and the larger the difference between the phase values ​​of the current point at the angles corresponding to the maximum and minimum high reflectivity, the more the phase value needs to be modified.

[0069] Preferably, the phase correction value extraction process provided in this embodiment is illustrated in the following diagram. Figure 3 As shown.

[0070] Step S4: Based on the difference in phase values ​​between each point at different angles and the distance from each point to the nearest edge of the die-casting part, determine the interference degree of each point, and combine the phase correction value to determine the phase correction value of each point at any angle.

[0071] Die-cast parts also have hollow areas. The edges of these hollow areas may experience interference due to optical effects such as scattering and diffraction, potentially causing instability or distortion in the interference signal of the surrounding area. This leads to inaccurate phase data and affects the edges of the hollow areas. Furthermore, the hollow areas cannot receive reflected signals, and the closer the distance to the hollow area, the greater the impact. Therefore, based on the differences in phase values ​​at different angles and the distance from each point to the nearest edge of the die-cast part, the interference level at each point is determined as follows:

[0072] Calculate the average value of the phase difference between all pairs of angles for each point, and combine the distance from each point to the nearest edge of the die casting with the average value to obtain the interference degree of each point.

[0073] It should be noted that there are many methods to measure the differences between data. In this embodiment, the difference between the phase values ​​of each point at any two angles is measured by calculating the absolute value of the difference between the phase values ​​of each point at any two angles. Implementers may also use other methods such as ratios to measure the differences between data, depending on the specific circumstances. This embodiment does not impose any special restrictions on the selection of methods for measuring the differences between data.

[0074] It should be understood that fusion refers to the result of combining two or more indicators through positive fusion, that is, combining two or more indicators by means of addition or multiplication to obtain a comprehensive indicator, thereby more comprehensively and accurately evaluating a phenomenon or problem. This fusion method is not limited to simple arithmetic operations, but can also include more complex statistical models and analytical methods. Implementers can choose according to specific circumstances, and this embodiment does not impose any special restrictions.

[0075] Preferably, in this embodiment, the interference degree of each point is the product of the distance from each point to the nearest edge of the die casting and the average value; in practical applications, as another implementation, the interference degree of each point is an exponential function value with the natural constant as the base and the sum of the distance from each point to the nearest edge of the die casting and the average value as the independent variable.

[0076] Based on the interference levels at each point, it can be understood that the greater the distance from the current point to the nearest edge of the die-cast part, the greater the potential impact, indicating that the point is more likely to be affected by the hollowed-out area. Furthermore, the greater the difference in phase values ​​between different angles at the current point, the more likely the point is to be affected by the hollowed-out area, thus the greater the interference level at the current point. Conversely, the greater the distance from the current point to the nearest edge of the die-cast part, the smaller the potential impact, indicating that the point is less likely to be affected by the hollowed-out area. Furthermore, the smaller the difference in phase values ​​between different angles at the current point, the less likely the point is to be affected by the hollowed-out area, thus the less the interference level at the current point.

[0077] Furthermore, based on the interference level at each point and in conjunction with the phase correction value, the phase correction value at each point at any angle is determined to assess the influence of the hollowed-out area on the phase measurement. Specifically:

[0078] The expression for the phase correction value of point j at angle i is: In the formula, A i,j B represents the phase correction value of point j at angle i;j β represents the interference level at point j; β represents the preset value.

[0079] It should be noted that the preset value is set manually. In this embodiment, the preset value is 0.7. The implementer can also set it according to the specific situation. This embodiment does not impose any special restrictions.

[0080] Step S5: Based on the phase correction value and the difference between the phase values ​​at each point at any angle, and the angle between the tangent plane at each point and the laser beam, determine the phase reliability at each point at any angle, and combine the phase correction value to determine the final phase value at each point, and measure the surface roughness of the die-cast part.

[0081] During multi-angle information fusion, the reliability of phase information obtained from each angle measurement varies. The smaller the difference between the initial and corrected phase information, the more reliable the information. Furthermore, the higher the accuracy, the more perpendicular the laser irradiation angle is to the die-cast graphics card under test. Therefore, based on the phase correction value and the difference between the phase values ​​at any given angle, as well as the angle between the tangent plane at each point and the laser beam, the phase reliability at any given angle is obtained, specifically:

[0082] Phase reliability Z at point j under angle i i,j The expression is: In the formula, Z i,j θ represents the phase reliability of point j at angle i; i,j represents the acute angle between the laser beam at point j and the tangent plane at point j at the i-th angle; exp[] represents the exponential function with the natural constant as the base; tan() represents the tangent function.

[0083] Based on the phase reliability of each point at any angle, it can be understood that the smaller the difference between the phase correction value and the phase value at the current point at the current angle, the more accurate the direct measurement result. Furthermore, the smaller the difference between the acute angle between the laser beam and the tangent plane at the current point and 90° during laser measurement, the more accurate the laser beam is, indicating that the laser beam is directly facing the measured position, thus increasing reliability and the phase reliability of the current point. Conversely, the larger the difference between the phase correction value and the phase value at the current point at the current angle, the less accurate the direct measurement result. Also, the larger the difference between the acute angle between the laser beam and the tangent plane at the current point and 90° during laser measurement, the lower the reliability and the smaller the phase reliability of the current point.

[0084] Furthermore, based on the reliability of laser measurements at each location at each angle, multi-angle phase information fusion is performed to obtain the final phase value for each point, specifically:

[0085] The final phase value P of point j j The expression is: In the formula, Z i,j A represents the phase reliability of point j at angle i; i,j M represents the phase correction value of point j at angle i; M represents the number of all angles.

[0086] Based on the final phase values ​​at each point, it can be understood that... This represents the result of a weighted calculation based on the phase reliability and phase value of the i-th point on the die-cast surface at the j-th angle in laser measurement, i.e., the final phase value. The more reliable the measurement result, the more phase information of the current point should be retained; conversely, the less reliable the measurement result, the less phase information of the current point should be retained.

[0087] Preferably, the schematic diagram of the final phase value acquisition process provided in this embodiment is as follows: Figure 4 As shown.

[0088] Furthermore, the mean of the phase values ​​at all angles for each point is calculated and denoted as the mean phase value for each point. The difference between the final phase value and the mean phase value for each point is used as the input to the phase-height formula, and the height of each point is output.

[0089] A rectangular coordinate system is constructed with the lower left corner of the die-cast part surface as the origin. The two-dimensional position coordinates and height of all points are used as input to the point cloud model, and a three-dimensional point cloud is output. The three-dimensional point cloud is then used as input to 3D modeling software to output the three-dimensional morphology of the die-cast part surface. Based on the three-dimensional morphology, the roughness parameters of the die-cast part surface are calculated using the arithmetic mean roughness formula.

[0090] Among them, the phase-height formula, the construction process of three-dimensional point clouds, the use of 3D modeling software, the construction of three-dimensional morphology, and the process of obtaining roughness parameters based on three-dimensional morphology and using the arithmetic mean roughness formula are all well-known technologies. The specific calculation process and related principles of construction will not be elaborated here.

[0091] It should be noted that the order of the embodiments described above is merely for descriptive purposes and does not represent the superiority or inferiority of the embodiments. Furthermore, specific embodiments of this specification have been described above. Additionally, the processes depicted in the accompanying drawings do not necessarily require a specific or sequential order to achieve the desired results. In some implementations, multitasking and parallel processing are possible or may be advantageous.

[0092] The various embodiments in this specification are described in a progressive manner. The same or similar parts between the various embodiments can be referred to each other. Each embodiment focuses on describing the differences from other embodiments.

[0093] The above-described embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them; modifications to the technical solutions described in the foregoing embodiments, or equivalent substitutions of some of the technical features, do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application, and should all be included within the protection scope of this application.

Claims

1. A method for measuring the surface roughness of aluminum alloy die-cast parts for computer graphics cards, characterized in that, The method includes the following steps: The phase values ​​of various points on the surface of the aluminum alloy die-cast part of the computer graphics card are obtained by using a laser beam at different angles, and the aluminum alloy die-cast part of the computer graphics card is denoted as the die-cast part. Based on the difference between the phase value of each point at any angle and the average distribution of the phase values ​​of all points on the surface of the die casting, the phase jump degree of each point at any angle is determined. Combined with the difference between the phase values ​​of any two adjacent points in the neighborhood of each point at any angle, the reflection intensity of each point at any angle is determined. Based on the difference between the reflection intensity of each point at any angle and the extreme distribution of reflection intensity of all points on the die-cast surface, the high reflection influence degree of each point at any angle is determined; based on the difference between the high reflection influence degree of each point at any angle and the maximum value of the high reflection influence degree of all points on the die-cast surface, as well as the difference between the phase values ​​of each point at the angles corresponding to the maximum and minimum high reflection influence degree, and combined with the phase values ​​of each point at any angle, the phase correction value of each point at any angle is determined; Based on the difference in phase values ​​between each point at different angles, and the distance from each point to the nearest edge of the die-casting part, the interference degree of each point is determined, and combined with the phase correction value, the phase correction value of each point at any angle is determined. Based on the phase correction value and the difference between the phase values ​​at each point at any angle, as well as the angle between the tangent plane at each point and the laser beam, the phase reliability at each point at any angle is determined. Combined with the phase correction value, the final phase value at each point is determined, and the surface roughness of the die-cast part is measured.

2. The method for measuring the surface roughness of aluminum alloy die-cast parts for computer graphics cards as described in claim 1, characterized in that, The phase jump degree at any angle is the difference between the phase value of each point at any angle and the average phase value of all points on the surface of the die casting.

3. The method for measuring the surface roughness of a computer graphics card aluminum alloy die-cast part as described in claim 1, characterized in that, The method for determining the reflection intensity at each point under any given angle is as follows: Calculate the difference between the phase values ​​of any two adjacent points in the neighborhood of each point at any angle; Calculate the mean of the phase values ​​of any two adjacent points in the neighborhood of each point at any angle, and calculate the ratio of the mean of the phase values ​​to the difference between the phase values. Take the average level of the ratio of all adjacent points in the neighborhood of each point at any angle as the reflection intensity of each point at any angle.

4. The method for measuring the surface roughness of aluminum alloy die-cast parts for computer graphics cards as described in claim 1, characterized in that, The method for determining the high reflection influence of each point at any angle is as follows: For the reflection intensity at each point under all angles, calculate the range of all reflection intensities; The ratio of the reflection intensity of each point at any angle to the range is taken as the high reflection influence degree of each point at any angle.

5. The method for measuring the surface roughness of aluminum alloy die-cast parts for computer graphics cards as described in claim 1, characterized in that, The expression for the phase correction value of each point at any given angle is: X i ′ ,j =X i,j -[(G i,j -g j )×ΔX j In the formula, X i ′ ,j X represents the phase correction value of point j at angle i; i,j G represents the phase value of point j at angle i; i,j Indicates the high reflectivity influence of point j at angle i; g j This represents the minimum high reflectivity influence of point j across all angles; ΔX j This represents the difference in phase value between point j at the angles corresponding to the maximum and minimum high reflectivity.

6. The method for measuring the surface roughness of a computer graphics card aluminum alloy die-cast part as described in claim 1, characterized in that, The method for determining the interference level at each point is as follows: Calculate the average value of the phase difference between all pairs of angles for each point, and combine the distance from each point to the nearest edge of the die casting with the average value to obtain the interference degree of each point.

7. The method for measuring the surface roughness of a computer graphics card aluminum alloy die-casting part as described in claim 5, characterized in that, The method for determining the phase correction value of each point at any given angle is as follows: In the formula, A i,j B represents the phase correction value of point j at angle i; j β represents the interference level at point j; β represents the preset value.

8. The method for measuring the surface roughness of a computer graphics card aluminum alloy die-cast part as described in claim 7, characterized in that, The expression for the phase reliability of each point at any given angle is: In the formula, Z i,j θ represents the phase reliability of point j at angle i; i,j represents the acute angle between the laser beam at point j and the tangent plane at point j at the i-th angle; exp[] represents the exponential function with the natural constant as the base; tan() represents the tangent function.

9. The method for measuring the surface roughness of a computer graphics card aluminum alloy die-cast part as described in claim 1, characterized in that, The expression for the final phase value of each point is: In the formula, P j Z represents the final phase value at point j; i,j A represents the phase reliability of point j at angle i; i,j M represents the phase correction value of point j at angle i; M represents the number of all angles.

10. The method for measuring the surface roughness of a computer graphics card aluminum alloy die-cast part as described in claim 1, characterized in that, The measurement of the surface roughness of the die-cast part includes: Calculate the average phase value at all angles for each point, and record it as the average phase value for each point. Use the difference between the final phase value and the average phase value for each point as the input to the phase-height formula, and output the height of each point. A rectangular coordinate system is constructed with the lower left corner of the die-cast part surface as the origin. The two-dimensional position coordinates and height of all points are used as input to the point cloud model, and a three-dimensional point cloud is output. The three-dimensional point cloud is then used as input to 3D modeling software to output the three-dimensional morphology of the die-cast part surface. The surface roughness parameters of the die-cast part are calculated based on the three-dimensional morphology and using the arithmetic mean roughness formula.

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