Method for measuring surface roughness of aluminum alloy die casting of computer graphics card

Abstract

The invention relates to the technical field of die casting surface roughness measurement, in particular to a method for measuring the surface roughness of a computer graphics card aluminum alloy die casting, and the method comprises the steps: calculating the surface roughness of the die casting based on the difference between the phase value of each point position at any angle and the average distribution condition of the phase values of all point positions on the surface of the die casting; determining the reflection intensity by combining the difference between the phase values of any two adjacent point locations in the neighborhood of each point location; determining the high reflection influence degree based on the difference between the reflection intensity of each point location at any angle and the extreme distribution condition of the reflection intensity of all point locations on the surface of the die casting; and measuring the roughness of the surface of the die casting based on the difference between the phase correction value and the phase value of each point location at any angle and the included angle between the tangent plane where each point location is located and the laser beam. The invention aims to improve the precision of the surface roughness measurement result of the aluminum alloy die casting of the computer graphics card.

Description

Technical Field

[0001] The present application relates to the technical field of die-casting surface roughness measurement, and in particular to a method for measuring the surface roughness of a computer graphics card aluminum alloy die-casting. Background Art

[0002] The surface roughness of aluminum alloy die castings for computer graphics cards has an important impact on heat dissipation, reliability and processing accuracy. Especially in high-performance graphics cards, the surface finish is directly related to thermal conductivity and assembly quality. Therefore, accurately measuring the surface roughness of aluminum alloy die castings for graphics cards is a key link in ensuring product quality. At present, traditional contact measurement methods (such as profilometers) have the limitation of being difficult to adapt to complex microstructures and easily damaged surfaces, while optical non-contact measurement (such as laser interferometry) can measure complex surfaces with high precision and efficiency, obtain microscopic roughness parameters, and accurately obtain the surface roughness measurement results of aluminum alloy die castings for computer graphics cards.

[0003] In the prior art, when using laser interferometry to measure the surface roughness of aluminum alloy die castings, the laser is divided into a reference beam and a measured beam. After reflection, the beams are combined to generate interference fringes. The microscopic height difference of the die casting surface is accurately measured by the phase change of the interference fringes, thereby calculating the surface roughness. However, the surface of aluminum alloy is smooth and highly reflective, which will cause strong specular reflection when the laser beam is irradiated on its surface, causing the measuring probe to receive too much light intensity, resulting in a decrease in the contrast of the interference fringes, thereby reducing the accuracy of the measurement results of the surface roughness of aluminum alloy die castings. Summary of the invention

[0004] In order to solve the above technical problems, the present application provides a method for measuring the surface roughness of aluminum alloy die-castings for computer graphics cards to solve the existing problems.

[0005] The surface roughness measurement method of a computer graphics card aluminum alloy die casting of the present application adopts the following technical solution:

[0006] An embodiment of the present application provides a method for measuring the surface roughness of an aluminum alloy die casting of a computer graphics card, the method comprising the following steps:

[0007] The phase value of each point on the surface of the aluminum alloy die-casting of the computer graphics card at different angles is obtained by using a laser beam, and the aluminum alloy die-casting of the computer graphics card is recorded as a die-casting;

[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, and 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 the reflection intensity of all points on the surface of the die casting, the high reflection influence of each point at any angle is determined; based on the difference between the high reflection influence of each point at any angle and the maximum value of the high reflection influence of all points on the surface of the die casting, and the difference between the phase values ​​of each point at the angles corresponding to the maximum and minimum high reflection influences, and combined with the phase value of each point at any angle, the phase correction value of each point at any angle is determined;

[0010] Based on the difference between the phase values ​​of each point at different angles and the distance from each point to the edge of the die casting closest to it, 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 difference between the phase correction value and the phase value of each point at any angle, and the angle between the tangent plane at each point and the laser beam, the phase reliability of each point at any angle is determined, and combined with the phase correction value, the final phase value of each point is determined to measure the roughness of the die-casting surface.

[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 of each point at any angle is:

[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, and 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 reflection influence degree of each point at any angle is:

[0017] Calculate the range of all reflection intensities for the reflection intensities at all points at all angles;

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

[0019] Preferably, the expression of the phase correction value of each point at any angle is: i′ ,j =X i,j -[(G i,j -g j )×ΔX j ]; where X i ′ ,j Indicates the phase correction value of point j at angle i; X i,j Indicates the phase value of point j at angle i; G i,j Indicates the high reflection influence of point j at angle i; g j Indicates the minimum value of the high reflection influence of point j at all angles; ΔX j It represents the difference between the phase values ​​at point j at the angles corresponding to the maximum and minimum high reflection influence.

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

[0021] The average value of the phase value difference between all any two angles of each point is calculated, and the distance from each point to the nearest edge of the die casting is fused 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: In the formula, A i,j Indicates the phase correction value of point j at angle i; B j represents the interference degree of point j; β represents the preset value.

[0023] Preferably, the expression of the phase reliability of each point at any angle is: In the formula, Z i,j Represents the phase reliability of point j at angle i; θ i,j It 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 an exponential function with a natural constant as the base; tan() represents the tangent function.

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

[0025] Preferably, the measuring of the roughness of the surface of the die casting comprises:

[0026] Calculate the average of the phase values ​​of each point at all angles, record it as the phase mean of each point, use the difference between the final phase value of each point and the phase mean 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-casting surface as the origin of the coordinate system. The two-dimensional position coordinates and heights of all points are used as the input of the point cloud model to output a three-dimensional point cloud. The three-dimensional point cloud is used as the input of the 3D modeling software to output the three-dimensional morphology of the die-casting surface. The roughness parameters of the die-casting surface are calculated based on the three-dimensional morphology and the arithmetic average roughness formula.

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

[0029] The present application uses non-contact laser interferometry technology to measure the surface roughness of computer graphics cards, and can obtain the measurement results of the surface roughness of aluminum alloy die-castings of computer graphics cards with high precision without causing surface scratches; the present application collects phase information at multiple angles, and can capture the reflection conditions of each position at different angles, which helps to locate areas affected by high reflection on the surface of aluminum alloy die-castings of computer graphics cards; further, 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; the present application analyzes the extremes of the reflection intensity of each point at all angles The distribution of the ends is compared with the reflection intensity of each point at any angle, and the degree of high reflection influence is constructed, which is helpful to identify and process high reflection areas. The high reflection influence and phase value are further combined to correct the phase error caused by high reflection and improve the accuracy of the data. The present application constructs the phase reliability by analyzing the difference between the phase correction value and the phase value of each point at any angle, as well as the angle between the tangent plane where each point is located and the laser beam. The reliability of the measurement results at each angle can be evaluated, which helps to select more reliable data for the calculation of the final phase value. Based on the reliability of each position in the laser measurement at each angle, multi-angle phase information fusion is performed to obtain a more accurate final phase value, thereby improving the accuracy of the overall measurement results. The present application compares the multi-angle phase information of each position on the surface of the aluminum alloy die-casting of the computer graphics card, and can screen out reliable and true phase information, and eliminate the data with large reflection interference, thereby improving the accuracy of the surface roughness measurement results of the aluminum alloy die-casting of the computer graphics card. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] In order to more clearly illustrate the technical solutions and advantages in the embodiments of the present application or the prior art, the drawings required for use in the embodiments or the prior art descriptions are briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0031] Figure 1 A flowchart of a method for measuring the surface roughness of an aluminum alloy die casting of a computer graphics card provided in one embodiment of the present application;

[0032] Figure 2 A schematic diagram of measuring aluminum alloy die castings for a computer graphics card provided in one embodiment of the present application;

[0033] Figure 3 A schematic diagram of a phase correction value extraction process provided by an embodiment of the present application;

[0034] Figure 4 A schematic diagram of a final phase value acquisition process provided in one embodiment of the present application. DETAILED DESCRIPTION

[0035] In order to further explain the technical means and effects adopted by this application to achieve the predetermined invention purpose, the following is a detailed description of the surface roughness measurement method of a computer graphics card aluminum alloy die casting proposed in this application, its specific implementation method, structure, characteristics and effects, in combination with the accompanying drawings and preferred embodiments. In the following description, different "one embodiment" or "another embodiment" does not necessarily refer to the same embodiment. In addition, specific features, structures or characteristics in one or more embodiments may be combined in any suitable form.

[0036] Unless defined otherwise, 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 belongs.

[0037] The following is a detailed description of a method for measuring the surface roughness of aluminum alloy die-castings for computer graphics cards provided in the present application in conjunction with the accompanying drawings.

[0038] An embodiment of the present application provides a method for measuring the surface roughness of a computer graphics card aluminum alloy die casting. Specifically, the following method for measuring the surface roughness of a computer graphics card aluminum alloy die casting is provided. Figure 1 , the method comprises the following steps:

[0039] Step S1: using a laser beam to obtain the phase value of each point on the surface of the aluminum alloy die-casting of a computer graphics card 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, so a Michelson interferometer is selected; the aluminum alloy die-casting of the graphics card is fixed on the sample stage of the interferometer to ensure that there is no vibration and 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 divided into two beams through a beam splitter, one beam is directed to the reference mirror, and the other beam is directed to the surface of the aluminum alloy die-casting of the computer graphics card to be tested; the background light is kept low in the measurement environment, 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-casting of the computer graphics card is complex. For example, if the surface has an inclined area, the phase values ​​of the surface of the aluminum alloy die-casting of the computer graphics card are collected at different angles by rotating the sample stage. In this embodiment, the rotation angle range of the sample stage is set to cover 0° to 90°, with each rotation of 10°. The implementer can also set it according to the specific situation. This embodiment does not impose any special restrictions.

[0042] Among them, for the convenience of description, the computer graphics card aluminum alloy die castings are referred to as die castings below.

[0043] Preferably, the measurement schematic diagram of the aluminum alloy die casting of the computer graphics card provided in this embodiment is as follows Figure 2 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, the phase jump degree of each point at any angle is determined, and the reflection intensity of each point at any angle is determined in combination with the difference between the phase values ​​of any two adjacent points in the neighborhood 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 is divided into a reference beam and a measuring beam. After being reflected on the graphics card surface, the two beams merge and an optical path difference occurs. The phase value of each point on the die casting surface is determined by the optical path difference between the measuring beam and the reference beam. The optical path difference directly corresponds to the phase difference, which indicates the height change of the point on the graphics card. Non-contact laser interferometry has high accuracy, but the surface material of the die casting is aluminum alloy. When the laser beam is irradiated, the intensity of the reflected light will be greatly enhanced, which may lead to errors in the roughness measurement results. Therefore, in order to ensure the accuracy of the surface roughness measurement, it is necessary to correct the error in the phase information of the high-reflection area on the die casting surface caused by the aluminum alloy material.

[0046] S201: Determine the phase jump degree of each point at any angle 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.

[0047] When the laser measurement beam is irradiated on the high-reflection area on the surface of the aluminum casting of the graphics card, the intensity of the reflected light is greatly enhanced, which may cause a sudden jump in the phase information, that is, the phase value changes dramatically, making the phase data discontinuous and difficult to accurately reflect the surface height. Therefore, by analyzing the difference between the phase value of each point at any angle and the average distribution of the phase value of all points on the surface of the die casting, the phase jump degree of each point at any angle is determined to reflect the jump of the phase value 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 for measuring the difference between data. In this embodiment, 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 surface of the die-casting is calculated to measure 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. The implementer may also use other methods that can measure the difference, such as ratio. This embodiment does not impose any special restrictions on the selection of the method for measuring the difference.

[0050] Among them, when the phase value of the current point on the die-casting surface is greater than the average value of the phase points of all points, it means that the phase value of the point has undergone a greater jump change, and the phase jump degree of the phase point of the point is greater; conversely, if the phase value of the current point is smaller than the average value of the phase points of all points, the phase value changes less and the phase jump degree is smaller.

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

[0052] The points where the phase value jumps in the die casting may be high-reflection areas. However, since the surface of the die casting is not flat and has structural changes such as depressions and projections, the phase of the laser interference is obtained based on the optical path difference. The optical path of the reference beam is fixed, while the optical path of the measurement beam changes in the flat part and the structural change (concave and convex) part of the die casting. The optical path difference of the two beams will also change, resulting in phase changes. Points with large phase jumps may also be caused by structural changes. Usually, the phase change caused by the structure is more continuous, while the phase change caused by high reflection is more jumpy. Therefore, based on the characteristics of whether the phase change is continuous, the reflection intensity of each point at any angle is determined, specifically:

[0053] A neighborhood W is divided with each point as the center, wherein the value of the neighborhood W is artificially set. In this embodiment, the value of W is 5, and the implementer can also set it by himself according to the specific situation. This embodiment does not impose any special restrictions.

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

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

[0056] Furthermore, the mean 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 of the phase values ​​to the difference between the phase values ​​is calculated, and 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 ratios of all adjacent points in the neighborhood of each point at any angle is calculated to measure the average level of the ratios of all adjacent points. The implementer 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 the method to measure the average level of data.

[0058] Furthermore, according to the reflection intensity of each point at 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 surface of the die-casting is smaller, it means that the area where the point is located is more likely to be a high-reflection area, and the phase change is uniformly jumped, while there is a continuous phase change in the structural point area. The greater the reflection intensity of the point, the more likely it is 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 greater the reflection intensity of the point; conversely, if the difference in phase value between two adjacent points in the neighborhood of the current point on the surface of the die-casting is greater, it means that the area where the point is located is less likely to be a high-reflection area, and the phase change jump is inconsistent, that is, the phase change in the structural point area is discontinuous, then the smaller the reflection intensity of the point, the less likely it is 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 the 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 the reflection intensity of all points on the surface of the die-casting, 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 value of the high reflection influence of all points on the surface of the die-casting, and the difference between the phase values ​​of each point at the angles corresponding to the maximum and minimum high reflection influence, and combined with the phase value of each point at any angle, determine the phase correction value of each point at any angle.

[0060] The points with higher reflection intensity are more likely to be in the high reflection area on the surface of the die casting. In the case of multi-angle laser interferometry, the incident light at different angles in the high reflection area will cause significantly different reflection conditions. The phase value changes with the angle. By analyzing the measurement information of each point at different angles, the phase is corrected. Specifically:

[0061] The reflection of each point on the aluminum alloy surface of the die-casting is different at different angles, and different phase values ​​will be generated under laser irradiation at different angles. Therefore, based on the difference between the reflection intensity of each point at any angle and the extreme distribution of the reflection intensity of all points on the die-casting surface, the high reflection influence of each point at any angle is determined to characterize the impact of high reflection on phase measurement, specifically:

[0062] Calculate the range of all reflection intensities for the reflection intensities at all points at all angles;

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

[0064] Further, the ratio of the reflection intensity of each point at any angle to the extreme difference is taken as the high reflection influence of each point at any angle;

[0065] According to the high reflection influence of each point at any angle, it can be understood that if the ratio of the reflection intensity of a point on the surface of the die-casting at the current angle to the extreme difference of all reflection intensities is larger, the high reflection influence of the point is larger, 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 at the current angle to the extreme difference of all reflection intensities is smaller, the high reflection influence of the 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 reflection influence degree of each point at any angle and the minimum value of the high reflection influence degree of all points on the surface of the die casting, and the difference between the phase values ​​of each point at the angles corresponding to the maximum and minimum high reflection influence degrees, and combined with the phase value of each point at any angle, the phase correction value of each point at any angle is determined, specifically:

[0067] Phase correction value X at point j at angle i i ′ ,j The expression is: X i ′ ,j =X i,j -[(G i,j -g j )×ΔX j ]; where X i,j Indicates the phase value of point j at angle i; G i,j Indicates the high reflection influence of point j at angle i; g j Indicates the minimum value of the high reflection influence of point j at all angles; ΔX j It represents the difference between the phase values ​​at point j at the angles corresponding to the maximum and minimum high reflection influence.

[0068] According to the phase correction value of each point at any angle, it can be understood that if the difference between the high reflection influence of the current point at the current angle and the minimum value of the high reflection influence of the current point at all angles is smaller, and the difference between the phase values ​​of the current point at the angles corresponding to the maximum and minimum high reflection influences is smaller, the degree to which the phase value needs to be modified will be smaller; conversely, if the difference between the high reflection influence of the current point at the current angle and the minimum value of the high reflection influence of the current point at all angles is greater, and the difference between the phase values ​​of the current point at the angles corresponding to the maximum and minimum high reflection influences is greater, the degree to which the phase value needs to be modified will be greater.

[0069] Preferably, the phase correction value extraction process diagram provided in this embodiment is as follows: Figure 3 shown.

[0070] Step S4: Based on the difference between the phase values ​​of each point at different angles and the distance from each point to the edge of the die casting closest to it, 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] There are also hollow areas in die castings. The edges of the hollow areas may cause interference due to optical effects such as scattering and diffraction, which may make the interference signal in the surrounding area unstable or distorted, resulting in inaccurate phase data and affecting the edges of the hollow areas. At the same time, the hollow areas cannot receive reflected signals. The closer to the hollow areas, the greater the impact. Therefore, based on the difference between the phase values ​​of each point at different angles and the distance from each point to the nearest edge of the die casting, the interference degree of each point is determined, specifically:

[0072] The average value of the phase value difference between all any two angles of each point is calculated, and the distance from each point to the nearest edge of the die casting is fused with the average value to obtain the interference degree of each point.

[0073] It should be noted that there are many methods for measuring the difference 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. The implementer may also adopt other methods such as ratios that can measure the difference between data according to the specific circumstances. This embodiment does not impose any special restrictions on the selection of methods for measuring the difference 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 adding or multiplying them together to obtain a comprehensive indicator, so as to more comprehensively and accurately evaluate a phenomenon or problem. This fusion method is not limited to simple arithmetic operations, but can also include more complex statistical models and analysis methods, which can be selected by the implementer according to the specific situation, and this embodiment does not impose any special restrictions.

[0075] Preferably, in the present embodiment, the interference degree of each point is the product of the distance from each point to the edge of the die-casting closest to it and the average value; in actual application, as other implementation methods, the interference degree of each point is an exponential function value with a natural constant as the base and the sum of the distance from each point to the edge of the die-casting closest to it and the average value as the independent variable.

[0076] According to the interference degree of each point, it can be understood that if the distance from the current point to the edge of the die-casting closest to it is greater, the possible impact is greater, and the point is more likely to be disturbed by the hollow area, and the greater the difference in phase values ​​between different angles of the current point is, the more likely the point is to be disturbed by the hollow area, and the greater the interference degree of the current point is; conversely, if the distance from the current point to the edge of the die-casting closest to it is greater, the possible impact is smaller, and the point is less likely to be disturbed by the hollow area, and the smaller the difference in phase values ​​between different angles of the current point is, the less likely the point is to be disturbed by the hollow area, and the smaller the interference degree of the current point is.

[0077] Further, based on the interference degree of each point, and in combination with the phase correction value, the phase correction value of each point at any angle is determined to judge the influence of the hollow area on the phase value measurement, specifically:

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

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

[0080] Step S5: Based on the difference between the phase correction value and the phase value of each point at any angle, and the angle between the tangent plane at each point and the laser beam, the phase reliability of each point at any angle is determined, and combined with the phase correction value, the final phase value of each point is determined to measure the roughness of the die-casting surface.

[0081] In the process of multi-angle information fusion, the reliability of the phase information obtained from each angle measurement is different. The smaller the difference between the initial point phase information and the corrected one, the more reliable it is. At the same time, when the laser irradiation angle is perpendicular to the die-casting of the graphics card to be tested, the higher its accuracy. Therefore, based on the difference between the phase correction value and the phase value of each point at any angle, and the angle between the tangent plane where each point is located and the laser beam, the phase reliability of each point at any angle is obtained, specifically:

[0082] Phase reliability Z of point j at angle i i,j The expression is: In the formula, Z i,j Represents the phase reliability of point j at angle i; θ i,j It 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 an exponential function with a natural constant as the base; tan() represents the tangent function.

[0083] According to the phase reliability of each point at any angle, it can be understood that if the difference between the phase correction value and the phase value of the current point at the current angle is smaller, it means that the direct measurement result is more accurate, and the difference between the acute angle between the laser beam and the tangent plane where the current point is located and 90° is smaller during the laser measurement of the current point at the current angle, it means that the laser beam is directly facing the position to be measured during the current measurement, then the reliability is higher, that is, the phase reliability of the current point is greater; conversely, if the difference between the phase correction value and the phase value of the current point at the current angle is greater, it means that the direct measurement result is less accurate, and the difference between the acute angle between the laser beam and the tangent plane where the current point is located and 90° is greater during the laser measurement of the current point at the current angle, then the reliability is lower, that is, the phase reliability of the current point is smaller.

[0084] Furthermore, according to the reliability of each position in the laser measurement at each angle, multi-angle phase information fusion is performed to obtain the final phase value of 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 It represents the phase correction value of point j at angle i; M represents the number of all angles.

[0086] According to the final phase value of each point, it can be understood that It represents the result of weighted calculation of phase reliability and phase value of the i-th point on the die casting surface in the laser measurement at the j-th angle, that is, the final phase value. The more reliable the measurement result is, the more phase information of the current point should be retained; conversely, the lower the reliability of the measurement result is, the more phase information of the current point can be retained.

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

[0088] Furthermore, the average of the phase values ​​at all angles of each point is calculated and recorded as the phase average of each point. The difference between the final phase value of each point and the phase average is used as the input of 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-casting surface as the origin of the coordinate system. The two-dimensional position coordinates and heights of all points are used as the input of the point cloud model to output a three-dimensional point cloud. The three-dimensional point cloud is used as the input of the 3D modeling software to output the three-dimensional morphology of the die-casting surface. The roughness parameters of the die-casting surface are calculated based on the three-dimensional morphology and the arithmetic average roughness formula.

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

[0091] It should be noted that the above sequence of the embodiments of the present application is for description only and does not represent the advantages and disadvantages of the embodiments. The above is a description of a specific embodiment of this specification. In addition, the processes depicted in the accompanying drawings do not necessarily require the specific order or continuous order shown to achieve the desired results. In some embodiments, multitasking and parallel processing are also possible or may be advantageous.

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

[0093] The embodiments described above are only used to illustrate the technical solutions of the present application, rather than to limit them. Modifications to the technical solutions recorded in the aforementioned embodiments, or equivalent replacement of some of the technical features therein, do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present application, and should all be included in the protection scope of the present application.

Claims

1. A method for measuring the surface roughness of aluminum alloy die castings for computer graphics cards, characterized in that: The method comprises the following steps: The phase value of each point on the surface of the aluminum alloy die-casting of the computer graphics card at different angles is obtained by using a laser beam, and the aluminum alloy die-casting of the computer graphics card is recorded as a die-casting; 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, and 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 the reflection intensity of all points on the surface of the die casting, the high reflection influence of each point at any angle is determined; based on the difference between the high reflection influence of each point at any angle and the maximum value of the high reflection influence of all points on the surface of the die casting, and the difference between the phase values ​​of each point at the angles corresponding to the maximum and minimum high reflection influences, and combined with the phase value of each point at any angle, the phase correction value of each point at any angle is determined; Based on the difference between the phase values ​​of each point at different angles and the distance from each point to the edge of the die casting closest to it, 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 difference between the phase correction value and the phase value of each point at any angle, and the angle between the tangent plane at each point and the laser beam, the phase reliability of each point at any angle is determined, and combined with the phase correction value, the final phase value of each point is determined to measure the roughness of the die-casting surface.

2. The surface roughness measurement method of a computer graphics card aluminum alloy die casting according to claim 1, characterized in that: 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.

3. The surface roughness measurement method of a computer graphics card aluminum alloy die casting according to claim 1, characterized in that: The method for determining the reflection intensity of each point at any angle is: 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, and 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 surface roughness measurement method of a computer graphics card aluminum alloy die casting according to claim 1, characterized in that: The method for determining the high reflection influence degree of each point at any angle is as follows: Calculate the range of all reflection intensities for the reflection intensities at all points at all angles; The ratio of the reflection intensity of each point at any angle to the extreme difference is taken as the high reflection influence degree of each point at any angle.

5. The surface roughness measurement method of a computer graphics card aluminum alloy die casting according to claim 1, characterized in that: The expression of the phase correction value of each point at any angle is: i ′ ,j =X i,j -[(G i,j -g j )×ΔX j ]; where X i ′ ,j Indicates the phase correction value of point j at angle i; X i,j Indicates the phase value of point j at angle i; G i,j Indicates the high reflection influence of point j at angle i; g j Indicates the minimum value of the high reflection influence of point j at all angles; ΔX j It represents the difference between the phase values ​​at point j at the angles corresponding to the maximum and minimum high reflection influence.

6. The surface roughness measurement method of a computer graphics card aluminum alloy die casting according to claim 1, characterized in that: The method for determining the interference degree of each point is as follows: The average value of the phase value difference between all any two angles of each point is calculated, and the distance from each point to the nearest edge of the die casting is fused 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 as claimed in claim 5, characterized in that: The method for determining the phase correction value of each point at any angle is as follows: In the formula, A i,j Indicates the phase correction value of point j at angle i; B j represents the interference degree of point j; β represents the preset value.

8. The method for measuring the surface roughness of a computer graphics card aluminum alloy die casting as claimed in claim 7, characterized in that: The expression of the phase reliability of each point at any angle is: In the formula, Z i,j Represents the phase reliability of point j at angle i; θ i,j It 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 an exponential function with a 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 casting according to claim 1, characterized in that: The expression of the final phase value of each point is: Where P j Represents the final phase value of point j; Z i,j A represents the phase reliability of point j at angle i; i,j It 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 aluminum alloy die castings for computer graphics cards as claimed in claim 1, characterized in that: The method of measuring the roughness of the die casting surface comprises: Calculate the average of the phase values ​​at all angles of each point, record it as the phase mean of each point, use the difference between the final phase value of each point and the phase mean as the input of 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-casting surface as the origin of the coordinate system. The two-dimensional position coordinates and heights of all points are used as the input of the point cloud model to output a three-dimensional point cloud. The three-dimensional point cloud is used as the input of the 3D modeling software to output the three-dimensional morphology of the die-casting surface. The roughness parameters of the die-casting surface are calculated based on the three-dimensional morphology and the arithmetic average roughness formula.

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