A method, system and equipment for evaluating surface quality of low-pressure inner cylinder shot peening

Abstract

The application discloses a low-pressure inner-cylinder shot blasting surface quality evaluation method, system and device, and relates to the technical field of surface quality evaluation. The application provides a low-pressure inner-cylinder shot blasting surface quality evaluation method, which comprises the following steps: obtaining a preset area to be subjected to surface quality evaluation after shot blasting treatment; dividing the preset area into at least two target areas based on part distribution information of the preset area; obtaining the structural complexity of all the target areas, and marking a target area with a structural complexity greater than a preset threshold as a first area, and marking the remaining target areas as second areas; evaluating a first quality score of the first area and a second quality score of the second area; and obtaining a surface quality score of the preset area according to the first quality score and the second quality score. The application aims to solve the technical problem that the surface quality evaluation after low-pressure inner-cylinder shot blasting treatment in the prior art usually adopts a single evaluation standard, and local quality misjudgment is prone to occur.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of surface quality evaluation of low-pressure inner cylinder shot blasting, and particularly relates to a surface quality evaluation method, system and equipment for low-pressure inner cylinder shot blasting. BACKGROUND

[0002] The low-pressure inner cylinder is an important component of a steam turbine, also known as a low-pressure high-temperature cylinder. During the processing, the low-pressure inner cylinder usually needs to be welded and the like, and after the welding treatment, shot blasting is usually needed. By introducing a residual compressive stress layer on the surface of the material, the fatigue life and stress corrosion resistance of the part can be significantly improved. The surface quality after shot blasting directly affects the fatigue resistance, corrosion resistance and service life.

[0003] However, in the prior art, the surface quality is usually roughly judged according to experience. The low-pressure inner cylinder has a complex structure, and the stress distribution, shot blasting coverage and roughness requirements are significantly different in different regions such as the transition fillet, hole edge and plane. However, the prior art usually adopts a single evaluation standard, which is prone to local quality misjudgment. SUMMARY

[0004] The main purpose of the present application is to provide a surface quality evaluation method, system and equipment for low-pressure inner cylinder shot blasting, which aims to solve the technical problem that the prior art usually adopts a single evaluation standard, which is prone to local quality misjudgment.

[0005] To achieve the above purpose, in a first aspect, the present application provides a surface quality evaluation method for low-pressure inner cylinder shot blasting, comprising:

[0006] obtaining a preset region to be evaluated for surface quality after shot blasting, dividing the preset region into at least two target regions based on part distribution information of the preset region;

[0007] According to the characteristic information of the at least two target regions, the structure complexity of all target regions is obtained, and the target region with structure complexity greater than a preset threshold is marked as a first region, and the remaining target regions are marked as a second region;

[0008] According to the parameter information of the first region and the second region, the first quality score of the first region is evaluated by a first evaluation model, and the second quality score of the second region is evaluated by a second evaluation model;

[0009] According to the first quality score and the second quality score, the surface quality score of the preset region is obtained.

[0010] Optionally, the step of dividing the preset region into at least two target regions based on the part distribution information of the preset region comprises:

[0011] According to the engineering requirements of the low-pressure inner cylinder, the shot peening surface range that needs to be evaluated for surface quality is determined and marked as a preset region;

[0012] The surface topography and internal structure data of the preset region are obtained by three-dimensional laser scanning, and the part distribution information of the preset region is determined based on the three-dimensional model information of the low-pressure inner cylinder;

[0013] According to the part distribution information of the preset region, the preset region is divided into at least two target regions.

[0014] Optionally, the step of obtaining the structural complexity of all target regions according to the feature information of the at least two target regions, and marking the target region with structural complexity greater than a preset threshold as a first region, and marking the remaining target regions as a second region, comprises:

[0015] According to the feature information of the at least two target regions, the geometric features, mechanical features and process features of all target regions are obtained;

[0016] According to the geometric features, mechanical features and process features of all target regions, the structural complexity is obtained by weighted calculation;

[0017] Among them, the geometric features include at least one of the curvature change rate of the curved surface, the edge density, the depth-width ratio of the hole / groove; the mechanical features include at least one of the stress gradient, the uniformity of residual stress distribution, the material thickness mutation index; the process features include at least one of the shot peening coverage rate, the projectile impact angle distribution.

[0018] Optionally, the step of evaluating the first quality score of the first region by a first evaluation model according to the parameter information of the first region and the second region, and evaluating the second quality score of the second region by a second evaluation model comprises:

[0019] The expression of the first evaluation model is:

[0020]

[0021] In the formula, represents the first quality score, represents the first region, represents the crater surface density, represents the crater surface density reference value, represents the curvature coupling function, denotes a depth power-law term, denotes a residual stress, denotes a local strain energy density, denotes a roughness gradient modulation term, denotes a curvature gradient norm, denotes a depth skewness, denotes a roughness kurtosis, denotes a regulation coefficient.

[0022] Optionally, the expression of the curvature coupling function is:

[0023]

[0024] wherein, and denote the curvature values in the principal curvature directions, respectively.

[0025] Optionally, the expression of the depth skewness is:

[0026]

[0027] wherein, denotes the depth of the crater in the first region, denotes the mean value of the crater depth, denotes the standard deviation of the crater depth;

[0028] The expression of the roughness kurtosis is:

[0029]

[0030] wherein, denotes the roughness of the surface in the first region, denotes the mean value of the roughness, denotes the standard deviation of the roughness, denotes an expectation operation.

[0031] Optionally, the step of evaluating the first quality score of the first region by a first evaluation model and the second quality score of the second region by a second evaluation model according to the parameter information of the first region and the second region comprises:

[0032] The expression of the second evaluation model is:

[0033]

[0034] wherein, denotes the second quality score, denotes the second region, denotes the determinant of the covariance matrix ​represents the crater depth of the second region, represents the mean crater depth, represents the surface roughness of the second region, represents the mean value of surface roughness, represents the nearest neighbor crater distance, represents the critical spacing datum, Represents the spacing decay exponent.

[0035] Optionally, the step of obtaining the surface quality score of the preset area according to the first quality score and the second quality score includes:

[0036] The expression for the surface quality score of the preset area is:

[0037]

[0038] Where, Indicates the surface quality score of the preset area, represents the j-th first quality score weight coefficient of the first region, represents the j-th first quality score of the first region, represents the number of the first region, Indicates the second area The second quality score weight coefficient, Indicates the second area A second quality rating, represents the number of the second region, represents the number of low-molecular-weight regions with a quality score below the base threshold, represents the penalty coefficient, Indicates the The area of ​​the low molecular weight region, represents the total area of ​​all low-molecular regions, represents the basic threshold of quality score, Indicates the Quality score of the low molecular weight region.

[0039] In a third aspect, the present application provides a low-pressure inner cylinder shot peening surface quality assessment system, comprising:

[0040] a target area acquisition module configured to acquire a preset area to be subjected to surface quality assessment after shot peening, and divide the preset area into at least two target areas based on component distribution information of the preset area;

[0041] a structure complexity acquisition module configured to acquire structure complexities of all the target regions according to the feature information of the at least two target regions, and mark a target region with a structure complexity greater than a preset threshold as a first region and mark the remaining target regions as second regions;

[0042] a model evaluation module configured to evaluate a first quality score of the first region by a first evaluation model and a second quality score of the second region by a second evaluation model according to the parameter information of the first region and the second region;

[0043] a surface quality score acquisition module configured to acquire a surface quality score of the preset region according to the first quality score and the second quality score.

[0044] In a fourth aspect, the present application provides a computer device, comprising a memory and a processor, wherein the memory stores a computer program capable of running on the processor, and the processor implements the method as described above when executing the computer program.

[0045] The present application can achieve the following beneficial effects:

[0046] The low-pressure inner cylinder shot peening surface quality evaluation method, system and device provided by the present application have at least the following beneficial effects: by dividing the preset region into a complex first region and a flat second region and marking according to the structure complexity, corresponding evaluation models can be used for different regions according to their characteristics, so that the shot peening effect of different regions can be more accurately reflected, and the accuracy of evaluation is improved. Through the double-model evaluation system, the first region focuses on microscopic morphology and residual stress, and the second region focuses on roughness and coverage, a mapping database of surface quality score and fatigue life can be established to guide the quantitative adjustment of shot peening process parameters such as jet angle and shot hardness, and shorten the process iteration cycle. BRIEF DESCRIPTION OF DRAWINGS

[0047] Figure 1 FIG. 1 is a flowchart of a low-pressure inner cylinder shot peening surface quality evaluation method according to an embodiment of the present application.

[0048] The implementation, functional features and advantages of the present application will be further described with reference to the embodiments and the accompanying drawings. DETAILED DESCRIPTION

[0049] The technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0050] It should be noted that all the direction indications (such as up, down, left, right, front, back, etc.) in the embodiments of the present application are only used to explain the relative position relationship, movement condition, etc. between components in a certain specific posture (as shown in the drawings), and if the specific posture changes, the direction indications will also change accordingly.

[0051] In the present application, unless otherwise explicitly specified and limited, the terms "connection", "fixation", etc. should be understood in a broad sense, for example, "fixation" can be fixed connection, or detachable connection, or integral; can be mechanical connection, or electrical connection; can be direct connection, or indirect connection through an intermediate medium; can be internal communication of two elements or interaction relationship between two elements, unless otherwise explicitly limited. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0052] In addition, if the present application embodiments involve "first", "second", etc. description, the "first", "second", etc. description is only for the purpose of description, and cannot be understood as indicating or implying the relative importance of the indicated technical features or implicitly indicating the number of the indicated technical features. Therefore, the features limited by "first", "second" can explicitly or implicitly include at least one of the features. In addition, the meaning of "and / or" appearing throughout the text includes three parallel schemes. For example, "A and / or B" includes A scheme, or B scheme, or A and B scheme. In addition, the technical solutions of each embodiment can be combined with each other, but it must be based on the realization of ordinary skilled in the art, when the combination of technical solutions appears contradictory or unachievable, it should be considered that the combination of technical solutions does not exist, nor within the scope of protection claimed by the present application.

[0053] Embodiment 1

[0054] Referring to Figure 1 The first embodiment of the present application provides a low-pressure inner cylinder shot blasting surface quality evaluation method, comprising the following operation steps:

[0055] S10, obtaining a preset area to be evaluated after shot blasting, based on the part distribution information of the preset area, the preset area is divided into at least two target areas.

[0056] Specifically, the low-pressure inner cylinder, also known as the low-pressure cylinder, is an important component of a steam turbine and is a general term in the field of steam turbines. It operates in the transition zone from positive pressure to negative pressure, withstands low-pressure and large-volume flow of steam, and needs to meet key requirements such as stiffness, exhaust passage design, and thermal stress control. Compared with high-pressure cylinders and medium-pressure cylinders, low-pressure cylinders have larger structural dimensions and unique vacuum protection mechanisms that can effectively prevent air infiltration and abnormal increases in exhaust temperature. The low-pressure inner cylinder operates in a low-pressure environment and has very low exhaust pressure, resulting in a significant increase in steam specific volume. The low-pressure inner cylinder is located inside the low-pressure outer cylinder and is subjected to high-temperature and high-pressure steam, which converts thermal energy into mechanical energy to drive the steam turbine. The low-pressure inner cylinder typically has a shell structure, with steam flowing from the center of the inner cylinder through the impeller, then to the outer cylinder, and finally to the rear stage. Since high-temperature and high-pressure steam needs to enter the low-pressure inner cylinder, the low-pressure inner cylinder needs to withstand high steam pressure. Except for the two end half-rings, which can be castings, the remaining parts are typically steel plate welded structures. The inner cylinder is divided into different steam extraction chambers by side plates, and struts are welded between the left and right chambers to ensure the rigidity of the structure.

[0057] Optionally, when obtaining the preset region, the overall range of the low-pressure inner cylinder after shot blasting is first determined, and a three-dimensional scanning device (such as a laser scanner) is used to comprehensively scan the low-pressure inner cylinder to obtain accurate three-dimensional model data. According to actual evaluation requirements and the functional characteristics of the low-pressure inner cylinder, the preset region to be evaluated for surface quality is selected on the three-dimensional model. For example, the peripheral regions of key parts that withstand high pressure and high temperature, such as the steam inlet, the exhaust port, and the welding area, should be designated as key preset regions.

[0058] The distribution information of the components in the preset region is analyzed, including the position, shape, and size of the components. This can be done by referring to the design drawings of the low-pressure inner cylinder and combining the three-dimensional model data for detailed analysis. According to the component distribution information, the preset region is divided into at least two target regions. The division principle can be based on factors such as the function of the components, structural similarity, and different effects that may be produced by shot blasting. For example, the region containing complex curved surfaces and small components is divided into one target region, and the relatively flat region with fewer components is divided into another target region.

[0059] S20, according to the characteristic information of the at least two target regions, obtaining the structural complexity of all target regions, and marking the target region with a structural complexity greater than a preset threshold as a first region, and marking the remaining target regions as second regions.

[0060] Optionally, for example, the low-pressure inner cylinder in the manufacturing process, the low-pressure inner cylinder parts or the upper and lower parts of the low-pressure inner cylinder need to be welded, and the weld area needs to be shot blasting after welding. When the shot blasting is carried out on the welding area of the low-pressure inner cylinder, the weld area may be a relatively flat straight line area and an arc surface with a certain arc. The preset area is the weld area, and the weld area is divided into a plurality of target areas.

[0061] For each target area, its feature information is extracted, including but not limited to surface curvature, roughness, and part density. The three-dimensional model data of the target area can be analyzed by using professional image processing software to obtain these feature information. For example, the surface curvature of the target area is evaluated by calculating the range of the surface curvature; the part density is evaluated by measuring the number and distribution density of the parts in the target area.

[0062] S30, according to the parameter information of the first area and the second area, the first quality score of the first area is evaluated by the first evaluation model, and the second quality score of the second area is evaluated by the second evaluation model.

[0063] Optionally, the first evaluation model and the second evaluation model are different, the first evaluation model is for the first area with more complex surface structure, and the second evaluation model is for the second area with more flat surface. By evaluating the surface quality in detail, the performance quality evaluation accuracy can be improved.

[0064] S40, according to the first quality score and the second quality score, the surface quality score of the preset area is obtained.

[0065] Optionally, the surface quality score of the preset area is obtained by weighted calculation of the first quality score and the second quality score. According to the area proportion or importance of the first area and the second area in the preset area, the weight of the first quality score and the second quality score is determined.

[0066] Embodiment 2

[0067] Based on embodiment 1, the embodiment provides a low-pressure inner cylinder shot blasting surface quality evaluation method, including the following operation steps:

[0068] S10, obtaining a preset area to be evaluated after shot blasting, and dividing the preset area into at least two target areas based on the part distribution information of the preset area.

[0069] Optionally, the step of dividing the preset area to be evaluated for surface quality after shot peening into at least two target areas based on the part distribution information of the preset area comprises:

[0070] S101, according to the engineering requirements of the low-pressure inner cylinder, determine the shot peening surface range that needs to be evaluated for surface quality, and mark it as a preset area;

[0071] Optionally, refer to the design specification, manufacturing process file and related quality standard of the low-pressure inner cylinder to understand the purpose and requirement of shot peening. For example, determine whether shot peening is to improve surface hardness, eliminate residual stress or improve surface roughness. According to the engineering requirements, preliminarily demarcate the shot peening surface range that needs to be evaluated for surface quality on the actual structure or three-dimensional model of the low-pressure inner cylinder. Consider the actual operation of shot peening and the area that may be affected, to ensure that the range is neither too large to increase the evaluation workload, nor too small to miss the key parts. For low-pressure inner cylinders with complex shapes, a zoning method can be used, or the entire structure can be divided into several possible evaluation areas according to experience for further screening later. Use professional drawing software (such as AutoCAD, SolidWorks, etc.) or directly on the three-dimensional model of the low-pressure inner cylinder to mark the determined evaluation range. The marking method can use different colors, lines or area filling to ensure clear identification. Number or name the preset area for accurate reference and record in the subsequent evaluation process.

[0072] S102, obtain the surface topography and internal structure data of the preset area by three-dimensional laser scanning, and determine the part distribution information of the preset area based on the three-dimensional model information of the low-pressure inner cylinder;

[0073] Optionally, select a suitable three-dimensional laser scanner, set the scanning parameters such as scanning resolution, scanning speed, etc. according to the size, shape and precision requirements of the preset area. Place the low-pressure inner cylinder on a stable scanning platform to ensure that it does not move or vibrate during scanning. Follow the predetermined scanning path to fully scan the preset area and obtain the three-dimensional point cloud data of its surface topography and internal structure.

[0074] Import the three-dimensional point cloud data obtained by scanning into professional data processing software (such as Geomagic, PolyWorks, etc.) for preprocessing operations such as denoising, filtering, registration, etc. to improve the quality and accuracy of the data. Use the surface reconstruction function of the software to convert the point cloud data into a triangular facet model or a NURBS surface model for more intuitive observation and analysis of the surface topography of the preset area.

[0075] The complete three-dimensional model information of the low-pressure inner cylinder is imported, and the scanned preset region model is compared and matched with the overall model. By analyzing the position, shape and size information of the parts in the three-dimensional model, the distribution of the parts in the preset region is determined. The relationship between the parts and the surface of the preset region can be clearly displayed by using methods such as layered display and cross-sectional view. The distribution information of the parts is recorded, including the number, type and position coordinates of the parts, which provides a basis for subsequent target region division.

[0076] S103, according to the part distribution information of the preset region, the preset region is divided into at least two target regions.

[0077] Optionally, the part distribution information in the preset region is analyzed in depth to find out the distribution differences and characteristics of different regions. For example, some regions may be concentrated with small parts, while other regions are mainly large structural parts. Considering the function, material, surface treatment requirements and other factors of the parts, the influence of these factors on the shot peening effect and surface quality evaluation is analyzed. According to the part distribution characteristics and analysis results, the division principle of the target region is determined. For example, it can be divided according to the density, size, functional similarity of the parts. Ensure that the target region after division has relatively independent characteristics and evaluation significance, which is convenient for subsequent evaluation methods and models.

[0078] S20, according to the characteristic information of the at least two target regions, the structure complexity of all target regions is obtained, and the target region with structure complexity greater than a preset threshold is marked as a first region, and the remaining target regions are marked as a second region.

[0079] Optionally, the step of obtaining the structure complexity of all target regions according to the characteristic information of the at least two target regions, and marking the target region with structure complexity greater than a preset threshold as a first region, and marking the remaining target regions as a second region, comprises:

[0080] S201, according to the characteristic information of the at least two target regions, the geometric characteristics, mechanical characteristics and process characteristics of all target regions are obtained; wherein the geometric characteristics include at least one of the surface curvature change rate, edge density, depth and width ratio of holes / grooves; the mechanical characteristics include at least one of stress gradient, residual stress distribution uniformity, material thickness mutation index; the process characteristics include at least one of shot peening coverage and projectile impact angle distribution.

[0081] Optionally, for each target region, use three-dimensional modeling software (such as SolidWorks, CATIA, etc.) or professional surface analysis tools to extract its surface curvature information. Calculate the rate of change of curvature at each point in the target region. By selecting multiple sampling points on the surface, calculate the ratio of the difference in curvature values of adjacent sampling points to the distance, and obtain the curvature rate of change. Statistically analyze the curvature rate of change of all sampling points in the target region, such as calculating the average, maximum, and minimum values, as the surface curvature rate of change feature of the target region.

[0082] Use image processing techniques or three-dimensional model analysis functions to identify the edges within the target region. The edge position can be determined by detecting the normal line change of the model surface, contour line, etc. Count the number of edges in the target region and calculate the edge density, which is the ratio of the number of edges to the area of the target region.

[0083] In the three-dimensional model, identify the holes and grooves in the target region. Accurate identification can be achieved by setting specific geometric shape recognition algorithms, such as contour analysis, volume analysis, etc. For each hole and groove, measure its depth and width, and calculate the ratio of depth to width. Statistically analyze the depth-to-width ratio of all holes and grooves in the target region to obtain this geometric feature of the target region.

[0084] Use finite element analysis software (such as ANSYS, ABAQUS, etc.) to perform mechanical analysis on the target region. According to the actual working conditions and stress conditions of the low-pressure inner cylinder, apply the corresponding load and boundary conditions. Calculate the stress values at each point in the target region, and calculate the stress gradient, i.e. the rate of change of stress in space, by differentiation or difference method. Analyze the distribution of stress gradient in the target region and extract key parameters such as maximum stress gradient and average stress gradient.

[0085] Similarly, use finite element analysis or experimental measurement methods (such as X-ray diffraction method, neutron diffraction method, etc.) to obtain the residual stress distribution data in the target region. Use statistical analysis methods such as calculating the standard deviation and coefficient of variation of residual stress to evaluate the uniformity of residual stress distribution.

[0086] Through three-dimensional model analysis or actual measurement, obtain the thickness information of the material in the target region. Identify areas where the material thickness changes abruptly and calculate the degree of abruptness. The material thickness abruptness index can be defined as the ratio of the thickness change to the average thickness of the adjacent region.

[0087] The shot coverage of the target area is obtained by referring to the shot process record or using image analysis method. The shot coverage of the target area can be obtained by coating a special developer on the surface of the target area, then performing shot processing, and then using an image acquisition device (such as a camera) to take a surface image. The image is analyzed using image processing software to calculate the ratio of the area covered by the projectile to the total area of the target area, and the shot coverage is obtained.

[0088] The impact angle distribution of the projectile in the target area is analyzed in combination with the process parameters of the shot equipment and the numerical simulation method. The numerical model of the shot process can be established to simulate the motion trajectory and impact angle of the projectile. The number or area proportion of the projectiles in different impact angle ranges is counted to obtain the impact angle distribution characteristics of the projectiles.

[0089] S202, the structure complexity is obtained by weighted calculation according to the geometric characteristics, mechanical characteristics and process characteristics of all target areas.

[0090] Optionally, according to the influence degree of the geometric characteristics, mechanical characteristics and process characteristics on the structure complexity, the analytic hierarchy process (AHP) can be used to determine the weight coefficients of each characteristic. For each characteristic value of each target area, since the dimension and value range may be different, the extreme value standardization method can be used for standardization processing. The structure complexity of the target area is obtained by weighted calculation, and the obtained structure complexity is compared with the preset threshold value obtained according to historical data or experience data. The target area with a structure complexity greater than the preset threshold value is marked as a first area, and the target area with a structure complexity less than or equal to the preset threshold value is marked as a second area. The division of the first area and the second area is not absolutely accurate, but only roughly divides the target area into a plurality of smaller sub-areas, so as to facilitate subsequent quality evaluation by the first quality evaluation model and the second quality evaluation model.

[0091] S30, according to the parameter information of the first area and the second area, the first quality score of the first area is evaluated by the first evaluation model, and the second quality score of the second area is evaluated by the second evaluation model.

[0092] Optionally, the step of evaluating the first quality score of the first area by the first evaluation model and evaluating the second quality score of the second area by the second evaluation model according to the parameter information of the first area and the second area comprises:

[0093] The expression of the first evaluation model is:

[0094]

[0095] In the formula, represents the first quality score, represents the first area, represents the crater density, represents the crater density reference value, represents the curvature coupling function, represents the depth power law term, represents the residual stress, represents the local strain energy density, represents the roughness gradient modulation term, represents the curvature gradient norm, represents the depth skewness, represents the roughness kurtosis, represents the adjustment coefficient.

[0096] represents the first quality score, used to evaluate the surface quality of the first region, with a higher score generally indicating better surface quality.

[0097] represents the crater density, representing the number of craters per unit area, reflecting the distribution of craters formed on the surface after shot peening, generally the larger the crater density, the more intense the effect of shot peening on the surface, which has a certain impact on the quality score. Data from surface image analysis (SEM / optical profiler).

[0098] represents the crater density reference value, serving as a reference standard for comparison with the actual crater density.

[0099] represents the curvature coupling function, considering the effect of surface curvature on the quality score, calculated by the curvature value in the principal curvature direction.

[0100] represents the depth power law term, where, represents the depth of the crater, is the power index, a nonlinear amplification of the depth of the residual stress, this term reflects the effect of crater depth on the quality score. The depth of the crater can be obtained by nanoindentation / confocal microscopy.

[0101] represents the residual stress, the stress remaining in the material after shot peening, which affects the performance and surface quality of the material, directly representing the shot peening effect, which can be obtained by X-ray diffraction (XRD).

[0102] represents the local strain energy density, representing the local strain energy distribution of the material, related to the residual stress and deformation of the material. The expression of is: ; in the formula, represents the stress tensor component, which describes the stress state inside the material. represents the strain tensor component, which describes the deformation of the material. characterizes the energy of local plastic deformation accumulation, high strain energy regions allow lower residual stress. residual stress is measured by point-by-point measurement of X-ray diffraction.

[0103] reflects the ratio of residual stress to local strain energy density, both excessive residual stress and unreasonable local strain energy density distribution can affect the performance and surface quality of the material.

[0104] represents the roughness gradient modulation term, which considers the influence of surface roughness gradient on quality score, areas with larger roughness gradient may have poor surface quality, this modulation term adjusts the quality score. Its expression is: ;

[0105] In the formula, represents the gradient of surface roughness, which represents the rate of change of roughness in space, is a constant that controls the change speed of the tanh function. When the roughness gradient , retains the score, when , quickly approaches 0, inhibiting the contribution of abrupt regions. Prevents local roughness mutation (such as scratches, uncovered areas) from causing false high scores.

[0106] represents the curvature gradient norm, which reflects the degree of change of surface curvature, and punishes regions with abrupt curvature (such as sharp edges, grooves).

[0107] reflects the relationship between the distribution of crater depth and the distribution of surface roughness. as a modulation coefficient, controls the influence of this ratio on the quality score. The exponential function makes the influence of this ratio on the quality score nonlinear, when is larger, the quality score will decrease significantly.

[0108] Optionally, the expression of the curvature coupling function is:

[0109]

[0110] In the formula, and respectively represent the curvature value in the principal curvature direction, which is used to describe the bending degree of the surface.

[0111] For the curvature amplitude term, the crater density requirement of high curvature area (such as edge, groove) is strengthened. For the curvature product term, the crater density requirement of convex surface is slightly weakened, and the curvature influence is retained; for the saddle-shaped surface , it is significantly inhibited.

[0112] Optionally, the expression of the depth skewness is as follows:

[0113]

[0114] In the formula, represents the depth of the crater in the first area, represents the mean value of the crater depth (the average value of all crater depths), represents the standard deviation of the crater depth (reflecting the dispersion degree of the crater depth). is the expectation operation, which represents the average of a random variable.

[0115] When , it indicates that the depth distribution is left-skewed, and most of the craters do not reach the required depth, so the score is reduced; the process requirement is .

[0116] The expression of the roughness kurtosis is as follows:

[0117]

[0118] In the formula, represents the roughness of the surface in the first area, represents the mean value of the roughness (the average value of the surface roughness), represents the standard deviation of the roughness (reflecting the dispersion degree of the surface roughness), represents the expectation operation.

[0119] When , it indicates that the roughness distribution is sharp (local abnormal protrusion), and the score is attenuated.

[0120] Through the comprehensive effect of the above items, the first evaluation model can comprehensively and comprehensively evaluate the surface quality of the first area, and provide a scientific basis for the shot peening quality control of the low-pressure inner cylinder.

[0121] In order to facilitate the understanding of the above first quality score acquisition process of the first area, the following examples are given:

[0122] Scenario setting: evaluate the flange root (first area ) of a certain type of low-pressure inner cylinder, which has complex geometry (curvature radius ), and needs to be evaluated after shot peening. The process target Passing threshold.

[0123] Geometric parameters are as follows:

[0124] Principal curvatures , (convex surface, );

[0125] Curvature gradient = 0.15 .

[0126] Crater parameters:

[0127] Crater surface density (Passing range: 150-200 );

[0128] Crater depth (mean , standard deviation );

[0129] Depth skewness (left skewed, but meets requirements).

[0130] Mechanical parameters:

[0131] Residual stress (X-ray diffraction measurement);

[0132] Local strain energy density (computed after strain field measured by DIC technique).

[0133] Roughness parameters: surface roughness (mean , standard deviation );

[0134] Roughness kurtosis (passing threshold requirements);

[0135] Roughness gradient (gradient modulation term ).

[0136] Other parameters:

[0137] Crater density reference value ; adjustment coefficient ; power law index ( dynamic adjustment to ( because ).

[0138] Distribution calculation results are as follows:

[0139] Curvature coupling function: ;

[0140] Depth power-law term: ;

[0141] Stress-strain ratio term: .

[0142] Molecular integral term (numerical approximation): ;

[0143] Denominator integral term: ;

[0144] Exponential term: ;

[0145] Final score (dimensionless):

[0146] Normalized score: assuming a baseline value of 100,000 corresponds to , then the actual .

[0147] , the product is determined to be unqualified.

[0148] Optionally, the step of evaluating the first quality score of the first region by a first evaluation model and the second quality score of the second region by a second evaluation model according to the parameter information of the first region and the second region comprises:

[0149] The expression of the second evaluation model is:

[0150]

[0151] wherein, represents the second quality score, represents the second region, represents the determinant of the covariance matrix , represents the crater depth of the second region, represents the mean of the crater depth, represents the surface roughness of the second region, represents the mean of the surface roughness, represents the nearest neighbor crater spacing, represents the critical spacing reference, and represents the spacing decay exponent.

[0152] is the joint probability density function, and the two-dimensional Gaussian distribution restricts the crater depth and the roughness . The joint distribution of depth and roughness, ensuring both fluctuate within allowed ranges.

[0153] Covariance determinant, representing the parameter distribution range, the smaller the determinant, the higher the score.

[0154] The covariance matrix is defined as: ,

[0155] : Depth allowed fluctuation ±20%;

[0156] : Roughness allowed fluctuation ±15%;

[0157] : Correlation coefficient of depth and roughness.

[0158] The crater spacing function.

[0159] The nearest neighbor crater spacing, the actual measured value, the score decreases when the spacing is too large. The nearest neighbor crater spacing is an important parameter for measuring the uniformity of the surface crater distribution after shot peening, reflecting the spatial relationship between the craters formed by the impact of the shot on the material surface. In the acquisition process, high-resolution microscopes or three-dimensional profilometers can be used to scan the surface after shot peening to obtain the position and shape information of the craters, and through image processing or topography analysis software, the straight-line distance between each crater and its nearest neighbor crater is calculated, i.e. .

[0160] When , the function value tends to 1, significantly reducing the score.

[0161] The integral result is divided by the area of the region, making the score range standardized to ; the score of each infinitesimal dA is determined by the probability density and the spacing function.

[0162] For easy understanding, an example is given as follows:

[0163] Evaluation of a low-pressure inner cylinder after the second area is shot peened:

[0164] Target parameters: , , , .

[0165] Actual data:

[0166] Depth , roughness ;

[0167] Nearest neighbor crater spacing: .

[0168] Covariance matrix: ( , )

[0169] Assuming there is only one crater in a local area, the calculation steps are as follows:

[0170] Probability density term: If a point , , calculated .

[0171] Nearest neighbor crater spacing: ,but .

[0172] The local ratings are: .

[0173] S40: Obtain a surface quality score of the preset area according to the first quality score and the second quality score.

[0174] Optionally, the step of obtaining the surface quality score of the preset area according to the first quality score and the second quality score includes:

[0175] The expression for the surface quality score of the preset area is:

[0176]

[0177] Where, Indicates the surface quality score of the preset area, represents the j-th first quality score weight coefficient of the first region, represents the j-th first quality score of the first region, represents the number of the first region, Indicates the second area The second quality score weight coefficient, Indicates the second area A second quality rating, represents the number of the second region, represents the number of low-molecular-weight regions with a quality score below the base threshold, represents the penalty coefficient, Indicates the The area of ​​the low molecular weight region, represents the total area of ​​all low-molecular regions, represents the basic threshold of quality score, Indicates the Quality score of low molecular weight regions.

[0178] represents the jth first weight coefficient of the first region, and represents the importance of the quality score of the jth first region in the overall score. Different weight coefficients reflect the difference in the influence of each region on the overall quality. j The first region weight is usually higher than the second region because the first region is more complex and fatigue-sensitive.

[0179] represents the penalty coefficient, which is used to adjust the influence of the low-score region on the overall quality score. A larger penalty coefficient means that the low-score region has a greater negative impact on the overall score.

[0180] This part is the weighted sum of the quality scores of the first region and the second region.

[0181] This part is the penalty term for low-score regions whose quality scores are below the base threshold.

[0182] For each low-score region, calculate the area of the low-score region as a proportion of the total area of all low-score regions , reflecting the relative size of the low-score region in the overall low-score region.

[0183] Calculate the difference between the base threshold and the quality score of the low-score region . The larger the difference, the greater the gap between the quality of the low-score region and the qualified standard.

[0184] Subtract the penalty term from the overall quality score to reduce the positive impact of the low-score region on the overall quality score, reflecting its negative impact on the overall quality. The quality score of the complex region contributes more to the total score, reflecting its key influence on fatigue life. Even if most regions have high scores, a few low-score regions can still significantly lower the total score, avoiding the excessive influence of small-area low-score regions on the total score, while highlighting the severity of large-area low-score regions.

[0185] Embodiment 3

[0186] Based on embodiment 1, the low-pressure inner cylinder shot peening surface quality evaluation system comprises:

[0187] A target region acquisition module configured to acquire a preset region to be evaluated for surface quality after shot peening, and divide the preset region into at least two target regions based on part distribution information of the preset region. ​​

[0188] a structure complexity obtaining module configured to obtain structure complexities of all the target regions according to the feature information of the at least two target regions, and mark a target region with a structure complexity greater than a preset threshold as a first region and mark the remaining target regions as second regions;

[0189] a model evaluation module configured to evaluate a first quality score of the first region by a first evaluation model and a second quality score of the second region by a second evaluation model according to the parameter information of the first region and the second region;

[0190] a surface quality score obtaining module configured to obtain a surface quality score of the preset region according to the first quality score and the second quality score.

[0191] Embodiment 4

[0192] The embodiment provides a computer device, which comprises a memory and a processor, the memory stores a computer program capable of running on the processor, and the processor implements any of the above methods when executing the computer program.

[0193] Embodiment 5

[0194] The embodiment provides a computer readable storage medium, which stores a computer program capable of being loaded and executed by a processor to implement the above method.

[0195] The above is only the preferred embodiment of the present application, and does not limit the patent scope of the present application, and any equivalent structure or equivalent flow transformation using the content of the specification and drawings of the present application, or direct or indirect application in other related technical fields, are also included in the patent protection scope of the present application.

Claims

1. A method for evaluating the surface quality of low-pressure inner cylinder shot peening, characterized in that: include: Obtaining a predetermined area to be subjected to surface quality assessment after shot peening, and dividing the predetermined area into at least two target areas based on component distribution information of the predetermined area; Obtaining structural complexity of all target areas based on the feature information of the at least two target areas, and marking target areas with structural complexity greater than a preset threshold as first areas, and marking the remaining target areas as second areas; According to the parameter information of the first region and the second region, evaluating a first quality score of the first region by using a first evaluation model, and evaluating a second quality score of the second region by using a second evaluation model; Obtaining a surface quality score of the preset area according to the first quality score and the second quality score; The expression of the first evaluation model is: Where, represents the first quality score, Indicates the first area, represents the crater surface density, Indicates the base value of crater surface density, represents the curvature coupling function, represents the depth power law term, represents the residual stress, represents the local strain energy density, represents the roughness gradient modulation term, represents the curvature gradient norm, represents the depth skewness, represents the roughness kurtosis, represents the adjustment coefficient; The expression of the second evaluation model is: Where, represents the second quality score, Indicates the second area, Represents the covariance matrix The determinant of represents the crater depth of the second region, represents the mean crater depth of the second region, represents the surface roughness of the second region, represents the mean value of the surface roughness of the second region, represents the nearest neighbor crater distance, represents the critical spacing datum, Represents the spacing decay exponent.

2. The method for evaluating the surface quality of a low-pressure inner cylinder shot peening treatment according to claim 1, wherein: The step of obtaining a preset area to be subjected to surface quality assessment after shot peening treatment and dividing the preset area into at least two target areas based on component distribution information of the preset area includes: According to the engineering requirements of the low-pressure inner cylinder, determine the range of shot peening surfaces that need to be evaluated for surface quality and mark them as preset areas; Through 3D laser scanning, the surface topography and internal structure data of the preset area are obtained, and based on the 3D model information of the low-pressure inner cylinder, the component distribution information of the preset area is determined; The preset area is divided into at least two target areas according to the component distribution information of the preset area.

3. The surface quality evaluation method of low-pressure inner cylinder shot peening according to claim 1, characterized in that: The step of obtaining the structural complexity of all target areas based on the feature information of the at least two target areas, marking the target areas with structural complexity greater than a preset threshold as first areas, and marking the remaining target areas as second areas, includes: Acquire geometric features, mechanical features, and process features of all target areas based on feature information of the at least two target areas; According to the geometric characteristics, mechanical characteristics and process characteristics of all target areas, the structural complexity is obtained through weighted calculation; Among them, the geometric features include at least one of the surface curvature change rate, edge density, and the depth-to-width ratio of holes / grooves; the mechanical features include at least one of the stress gradient, residual stress distribution uniformity, and material thickness mutation index; and the process features include at least one of the shot peening coverage and the projectile impact angle distribution.

4. The surface quality evaluation method of low-pressure inner cylinder shot peening according to claim 1, characterized in that: The expression of the curvature coupling function is: Where, and Represent the curvature values ​​in the main curvature directions respectively.

5. The method for evaluating the surface quality of a low-pressure inner cylinder shot peening treatment according to claim 1, wherein: The expression for depth skewness is: Where, represents the depth of the crater in the first region, represents the mean crater depth of the first region, represents the standard deviation of crater depth; The expression of roughness kurtosis is: Where, represents the surface roughness of the first region, represents the mean value of the surface roughness of the first region, represents the standard deviation of roughness, Represents the expected operation.

6. The method for evaluating the surface quality of a low-pressure inner cylinder shot peening treatment according to claim 1, wherein: The step of obtaining the surface quality score of the preset area according to the first quality score and the second quality score includes: The expression for the surface quality score of the preset area is: Where, Indicates the surface quality score of the preset area, represents the j-th first quality score weight coefficient of the first region, represents the j-th first quality score of the first region, represents the number of the first region, Indicates the second area The second quality score weight coefficient, Indicates the second area A second quality rating, represents the number of the second region, represents the number of low-molecular-weight regions with a quality score below the base threshold, represents the penalty coefficient, Indicates the The area of ​​the low molecular weight region, represents the total area of ​​all low-molecular regions, represents the basic threshold of quality score, Indicates the Quality score of the low molecular weight region.

7. A low-pressure inner cylinder shot peening surface quality assessment system, characterized in that: include: a target area acquisition module configured to acquire a preset area to be subjected to surface quality assessment after shot peening treatment, and divide the preset area into at least two target areas based on component distribution information of the preset area; a structural complexity acquisition module configured to acquire the structural complexity of all target areas based on the feature information of the at least two target areas, and mark the target areas with structural complexity greater than a preset threshold as first areas, and mark the remaining target areas as second areas; a model evaluation module configured to evaluate a first quality score of the first region using a first evaluation model and to evaluate a second quality score of the second region using a second evaluation model based on parameter information of the first region and the second region; a surface quality score acquisition module, configured to acquire a surface quality score of the preset area according to the first quality score and the second quality score; The expression of the first evaluation model is: Where, represents the first quality score, Indicates the first area, represents the crater surface density, Indicates the base value of crater surface density, represents the curvature coupling function, represents the depth power law term, represents the residual stress, represents the local strain energy density, represents the roughness gradient modulation term, represents the curvature gradient norm, represents the depth skewness, represents the roughness kurtosis, represents the adjustment coefficient; The expression of the second evaluation model is: Where, represents the second quality score, Indicates the second area, Represents the covariance matrix The determinant of represents the crater depth of the second region, represents the mean crater depth of the second region, represents the surface roughness of the second region, represents the mean value of the surface roughness of the second region, represents the nearest neighbor crater distance, represents the critical spacing datum, Represents the spacing decay exponent.

8. A computer device, characterized in that: The method comprises a memory and a processor, wherein the memory stores a computer program that can be run on the processor, and the processor implements the method according to any one of claims 1 to 6 when executing the computer program.

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