A method and system for controlling the root cause of post-grinding fluorescent defects in turbine blades

Abstract

The application discloses a kind of turbine blade grinding after fluorescent defect root control method and system, it is related to turbine blade technical field, the present application adopts computer full-process closed-loop control, first obtains tenon tooth solidification characteristic parameter, constructs directional solidification multi-physics field coupling model and is solved to obtain transient multi-physics field data set;Again, through paste zone width two-stage quantization calculation, the shrinkage high-risk interval in tenon tooth grinding allowance range is determined;Based on risk interval, the optimal incremental drawing time correction calculation is completed, and qualified directional solidification process parameters are generated and verified;Finally, control equipment executes process, and realizes process solidification or reverse iterative correction by acquisition detection data.The present application eliminates the aggregation of microscopic shrinkage from the solidification source, realizes defect root, precision prevention and control, and has strong stability, which can significantly reduce the reject rate of blade production.

Description

Technical Field

[0001] This invention relates to the field of turbine blade technology, and specifically to a method and system for controlling the root causes of fluorescence defects after turbine blade grinding. Background Technology

[0002] Turbine blades for aero-engines are core hot-end load-bearing components of aero-engine power equipment. Their tenon structure, as a critical load-transfer point connecting the blade to the turbine disk, directly determines the engine's service safety, fatigue life, and reliability through its machining quality and metallurgical integrity. This is a core quality control aspect in the aero-engine manufacturing process. In the current industrial production of high-temperature alloy turbine blades, linear defects frequently appear in fluorescent penetrant testing after precision grinding of the tenon area. These defects have long been widely misdiagnosed in the industry as grinding cracks generated during the grinding process. Existing technologies focus on controlling defects through grinding process optimization, grinding parameter adjustment, and post-processing welding repair. However, these methods not only fail to completely eliminate the recurrence of defects but also compromise the load-bearing capacity and fatigue life of the tenon due to the welding repair process. The significantly reduced lifespan of turbine blades results in extremely high scrap rates and production costs, becoming a major challenge restricting the stable mass production of aero-engine turbine blades. Systematic metallurgical analysis and mechanistic studies have confirmed that the essence of this type of linear fluorescence defect is not grinding-induced cracks, but rather aggregated micro-shrinkage porosity caused by the solid-liquid phase shrinkage difference in the tenon area during the directional solidification process of the blade. This porosity is caused by the formation of isolated liquid phase regions and insufficient feeding, which are then torn along the shear direction under subsequent grinding stress, forming interconnected channels on the grinding surface. Existing technologies have completely deviated from the core direction of defect prevention and control, failing to trace the root cause of solidification for prevention and control. Furthermore, they lack quantitative and accurate methods for determining shrinkage porosity risk, controllable feeding capacity improvement models, and a closed-loop control system for the entire process, making it impossible to achieve root cause and stability control of this type of defect. Summary of the Invention

[0003] The purpose of this invention is to provide a method and system for controlling the root causes of fluorescence defects after turbine blade grinding, thereby solving the problems mentioned in the background art.

[0004] This invention is achieved through the following technical solution: A method for controlling the root cause of fluorescence defects after turbine blade grinding includes: S1. By obtaining the solidification characteristic parameters of the tenon, constructing and solving the directional solidification multiphysics coupling basic model, the transient multiphysics basic dataset of the tenon part during the entire solidification cycle is obtained. S2. Based on the transient multiphysics field dataset, perform quantitative calculation of the width of the mushy region to obtain the parameter set of the high-risk interval of shrinkage within the tenon grinding allowance range; S3. Based on the parameter set of the high-risk shrinkage zone, the optimal incremental pulling time correction calculation is performed to obtain the optimal process parameter set of the entire directional solidification process that has been verified by simulation. S4. With the optimal set of process parameters as the target, control the directional solidification equipment to execute the process, collect the quality inspection data after the tenon grinding, and complete the process solidification or reverse iterative correction of the calculation parameters of the preceding steps based on the inspection results, so as to realize the closed-loop control of the whole process.

[0005] Furthermore, In S1, the solidification characteristic parameters of the tenon include the three-dimensional digital model of the turbine blade, the grinding allowance parameters of the tenon design, the thermophysical property parameters of the alloy used in the blade, and the controllable process boundary parameters of the directional solidification equipment. When constructing the multiphysics coupling basic model, the spatial range corresponding to the grinding allowance of the tenon is locally densified into a mesh. The transient multiphysics basic dataset obtained by solving the problem includes at least the full-cycle transient temperature, solid-liquid phase fraction, solidification front temperature gradient, and solidification rate data of each mesh node in the tenon part.

[0006] Furthermore, In S2, the quantization calculation of the width of the mushy region includes two-level quantization calculation. First, the instantaneous width of the mushy region of each node within the grinding allowance range of the tenon tooth is obtained through the instantaneous mushy region width calculation formula. Then, the shrinkage loosening tendency feature value of each node is obtained through the mushy region feature integral value calculation formula. Based on the pre-calibrated shrinkage loosening risk threshold, the risk level classification and high-risk interval clustering are completed, and the high-risk interval parameter set of shrinkage loosening is output.

[0007] Furthermore, The formula for calculating the width of the instantaneous pasty region is: ; The formula for calculating the integral value of the mushy region feature is as follows: ; In the formula, Let be the instantaneous mushy region width of the i-th node within the tenon grinding allowance at time t. This is the liquidus temperature of the alloy. This refers to the solidus temperature of the alloy. Let be the solidification front temperature gradient of the i-th node at time t; Let be the integral value of the mushy region feature of the i-th node. Let be the moment when the temperature of the i-th node drops to the liquidus temperature. This is the moment when the temperature of the i-th node drops to the solidus temperature.

[0008] Furthermore, In S3, the optimal incremental pulling time correction calculation first matches the solidification time window corresponding to the high-risk shrinkage interval, and then calculates the optimal incremental pulling time for targeted shrinkage compensation using the optimal incremental pulling time correction formula. Based on this incremental pulling time, a set of directional solidification process parameters is generated, which is then substituted into the multi-physics coupling basic model to complete the simulation verification. After the verification is qualified, the optimal process parameter set is output.

[0009] Furthermore, The optimal incremental pull-out time correction formula is as follows: In the formula, To determine the optimal incremental pull time, This is the pre-calibrated correction factor for the feeding efficiency. This represents the integral value of the maximum pasty region characteristic within the high-risk range of the contraction process. This represents the maximum instantaneous width of the pasty region within the high-risk zone. The width of the critical paste-like region without shrinkage in the alloy.

[0010] Furthermore, In S4, the quality inspection data includes fluorescence penetrant detection data of the tenon grinding surface and metallographic microscopic analysis data within the tenon grinding allowance range; the fluorescence penetrant detection data includes at least the presence, spatial location, and quantity of linear fluorescence defects, and the metallographic microscopic analysis data includes at least the degree of aggregation, spatial distribution, and size of micro shrinkage.

[0011] Furthermore, In S4, the calculation parameters of the preceding steps are corrected by reverse iteration, including: correcting the shrinkage risk threshold based on the quality inspection data, correcting the shrinkage efficiency correction coefficient, correcting the boundary parameters of the multi-physics coupling basic model, and then re-executing the entire process loop from S1 to S4 until the quality inspection data meets the qualification standard.

[0012] Furthermore, The qualification criteria are that there are no linear fluorescence defects on the surface of the tenon grinding and no aggregated micro shrinkage porosity within the tenon grinding allowance. When the qualification criteria are met, the current optimal process parameter set is solidified and stored in the process database for mass production of the same type of blade.

[0013] Furthermore, A root cause control system for fluorescence defects after turbine blade grinding includes: The basic model building module receives the solidification feature parameters of the tenon and tooth, constructs and solves the directional solidification multiphysics coupling basic model, and outputs the transient multiphysics basic dataset of the tenon and tooth part throughout the entire solidification cycle. The shrinkage risk assessment module takes the transient multiphysics field basic dataset as input, and outputs a set of parameters for high-risk shrinkage intervals within the tenon grinding allowance range by quantizing the width of the smeared region. The process parameter generation module takes the parameter set of the high-risk shrinkage zone as input, and through the optimal incremental pulling time correction calculation, outputs the optimal process parameter set of the entire directional solidification process that has passed the simulation verification. The closed-loop control execution module uses the optimal process parameter set as input to control the directional solidification equipment to execute the process, collects quality inspection data after tenon grinding, and completes process solidification or reverse iteration to correct the calculation parameters of other functional modules based on the inspection results, thereby realizing closed-loop control of the entire process.

[0014] The beneficial effects of this invention are as follows: 1. For a long time, the industry has generally misjudged linear fluorescence defects after tenon grinding as grinding cracks, and only carried out symptomatic prevention and control by optimizing the grinding process and subsequent welding repair. This invention focuses on the essential mechanism of this defect, which is formed by the tearing of grinding stress through the aggregated micro shrinkage porosity during the solidification process. By optimizing the directional solidification process to open up the dendrite shrinkage compensation channel and eliminate the isolated liquid phase region, the micro shrinkage porosity within the tenon grinding allowance range is suppressed from the source. This can fundamentally eliminate the generation of linear fluorescence defects on the surface after grinding, and at the same time avoid damage to the mechanical properties of the tenon by the welding repair process, which greatly improves the service safety and service life of aero-engine turbine blades.

[0015] 2. Existing technologies lack quantitative methods for judging and controlling shrinkage porosity in tenon teeth. They rely solely on repeated trial and error adjustments based on manual experience, which is not only inefficient but also prone to problems such as insufficient feeding or over-adjustment of the process. This invention uses a two-level quantitative model based on instantaneous mushy zone width calculation and full-cycle feature integration to accurately determine the shrinkage porosity risk range within the tenon grinding allowance. Then, through an optimal incremental pulling time correction formula, it quantitatively matches the degree of shrinkage porosity risk with the need to improve feeding capacity. All process parameters are generated based on model calculation and experimental calibration, without fixed empirical values. This avoids defects caused by insufficient feeding and prevents new solidification defects such as impurities and freckles caused by over-adjustment of the pulling rate. It significantly improves the accuracy, reliability, and reproducibility of process control and can be adapted to the shrinkage porosity control needs of different alloy grades and tenon structures. Attached Figure Description

[0016] Fig. 1 This is a schematic diagram of the logic flow of the present invention; Fig. 2 This is a schematic diagram illustrating the essential cause of linear fluorescence defects on the surface of a tenon tooth grinding process. Detailed Implementation

[0017] The present invention will be further described in detail below with reference to the embodiments and accompanying drawings, but the embodiments of the present invention are not limited thereto.

[0018] See the example. Figs. 1-2 : A method for controlling the root cause of fluorescence defects after turbine blade grinding includes: S1. By obtaining the solidification characteristic parameters of the tenon, constructing and solving the directional solidification multiphysics coupling basic model, the transient multiphysics basic dataset of the tenon part during the entire solidification cycle is obtained. S2. Based on the transient multiphysics field dataset, perform quantitative calculation of the width of the mushy region to obtain the parameter set of the high-risk interval of shrinkage within the tenon grinding allowance range; S3. Based on the parameter set of the high-risk shrinkage zone, the optimal incremental pulling time correction calculation is performed to obtain the optimal process parameter set of the entire directional solidification process that has been verified by simulation. S4. With the optimal set of process parameters as the target, control the directional solidification equipment to execute the process, collect the quality inspection data after the tenon grinding, and complete the process solidification or reverse iterative correction of the calculation parameters of the preceding steps based on the inspection results, so as to realize the closed-loop control of the whole process.

[0019] Furthermore, In S1, the solidification characteristic parameters of the tenon include the three-dimensional digital model of the turbine blade, the grinding allowance parameters of the tenon design, the thermophysical property parameters of the alloy used in the blade, and the controllable process boundary parameters of the directional solidification equipment. When constructing the multiphysics coupling basic model, the spatial range corresponding to the grinding allowance of the tenon is locally densified into a mesh. The calculated transient multiphysics basic dataset includes at least the full-cycle transient temperature, solid-liquid phase fraction, solidification front temperature gradient, and solidification rate data of each mesh node in the tenon part.

[0020] In one embodiment, when constructing the multiphysics coupling basic model, the spatial range corresponding to the 0.3mm grinding allowance of the tenon is locally densified. Compared with the conventional mesh size of 0.5mm in non-core areas such as the blade body, the mesh size of the target area is reduced to 0.1mm. While controlling the overall computational load and ensuring computational efficiency, the calculation accuracy of solidification characteristics in small areas within the grinding allowance range is greatly improved, avoiding the omission of micro-shrinkage risk areas due to excessively large mesh size. After the model is constructed, transient solutions are performed on the entire cycle of the blade from the completion of casting to the complete solidification of the casting. Finally, the transient temperature, solid-liquid phase fraction, solidification front temperature gradient, and solidification rate data of each densified mesh node in the tenon part are output, forming a complete transient multiphysics basic dataset.

[0021] Furthermore, In S2, the quantization calculation of the width of the mushy region includes two-level quantization calculation. First, the instantaneous width of the mushy region of each node within the grinding allowance range of the tenon tooth is obtained through the instantaneous mushy region width calculation formula. Then, the shrinkage loosening tendency feature value of each node is obtained through the mushy region feature integral value calculation formula. Based on the pre-calibrated shrinkage loosening risk threshold, the risk level classification and high-risk interval clustering are completed, and the high-risk interval parameter set of shrinkage loosening is output.

[0022] In one embodiment, taking the Chinese DD6 single-crystal high-temperature alloy high-pressure turbine fir-shaped tenon blade as an example, for each 0.1mm fine-grid node within the 0.3mm grinding allowance range of the tenon, the solidification front temperature gradient, the 1315℃ solidus temperature, and the 1380℃ liquidus temperature of the DD6 alloy at each time step within the entire solidification cycle are extracted. Using the instantaneous mushy region width calculation formula, the instantaneous mushy region width for the entire cycle is calculated node by node and time step by time. This parameter directly characterizes the instantaneous size of the solid-liquid coexistence region at the node's corresponding position during solidification. The larger the mushy region width, the easier it is for dendrites to bridge and form an enclosed isolated liquid phase region, thus producing uncompensated micro-shrinkage porosity. Based on this, the moment each node enters the 1380℃ liquidus temperature is taken as the integration start point, and the moment it drops to the 1315℃ solidus temperature is taken as the integration end point, to calculate the instantaneous mushy region width. The full-cycle integral calculation yields the integral value of the mushy region characteristic at each node. This integral value integrates the two core influencing factors of the mushy region size and duration, accurately quantifying the tendency of micro-shrinkage formation at the corresponding location. The higher the integral value, the higher the risk of shrinkage formation. Subsequently, based on the shrinkage risk threshold pre-calibrated through solidification tests and metallographic verification of DD6 alloy standard test bars, each node is classified into risk levels. Then, high-risk nodes that are continuously distributed in space are clustered to accurately delineate the spatial location and geometric boundary range of the high-risk shrinkage zone at the tenon root fillet where defects frequently occur in production, which is 0.2mm × 0.4mm. At the same time, core feature parameters such as the maximum mushy region characteristic integral value and the maximum instantaneous mushy region width within the zone are extracted, ultimately forming a complete parameter set for the high-risk shrinkage zone, providing a precise target zone for targeted optimization of the subsequent shrinkage compensation process.

[0023] Furthermore, The formula for calculating the width of the instantaneous pasty region is: ; The formula for calculating the integral value of the mushy region feature is as follows: ; In the formula, Let be the instantaneous mushy region width of the i-th node within the tenon grinding allowance at time t. This is the liquidus temperature of the alloy. This refers to the solidus temperature of the alloy. Let be the solidification front temperature gradient of the i-th node at time t; Let be the integral value of the mushy region feature of the i-th node. Let be the moment when the temperature of the i-th node drops to the liquidus temperature. This is the moment when the temperature of the i-th node drops to the solidus temperature.

[0024] The formula for calculating the instantaneous mushy region width is based on the core correlation between the temperature gradient at the solidification front and the width of the mushy region during directional solidification, where the solidus temperature of the DD6 alloy is used. =1315℃, liquidus temperature =1380℃, all of which were accurately measured through standard material thermal analysis tests to ensure that the basic parameters calculated by the formula are accurate and reliable; The solidification front temperature gradient at time t of the i-th node at the root fillet of the tenon tooth obtained from S1 is given. For example, if the temperature gradient of a node at a critical solidification time step is 15℃ / mm, the instantaneous mushy region width at that time can be calculated as 4.33mm by substituting it into the formula. This value directly reflects the size of the mushy region at the solid-liquid interface at that position during solidification. The smaller the temperature gradient, the larger the width of the mushy region, and the easier it is for the dendrite feeding channel to close in advance. This formula can accurately restore the actual size of the mushy region at each time and position during solidification, and realize the transient accurate characterization of shrinkage risk. The formula for calculating the integral value of the mushy region characteristic transforms the transient characterization of shrinkage risk into a comprehensive quantitative indicator for the entire cycle by integrating the instantaneous width over the entire mushy region period. The aforementioned nodes... This is the 120th second after pouring (the starting moment when the temperature drops to 1380℃ and enters the paste-like zone). The integral interval, calculated at 240 seconds after pouring (the point at which the temperature drops to 1315℃ and the solidification is complete), fully covers the entire 120-second solid-liquid coexistence process at this node. The integral value of the mushy region characteristic at this node is 520 mm·s. This integral value includes both the size and duration characteristics of the mushy region. Compared to the single instantaneous width of the mushy region, it can more comprehensively and accurately determine the tendency of micro-shrinkage formation at the corresponding location, providing a quantifiable and reproducible basis for subsequent risk level classification.

[0025] Furthermore, In S3, the optimal incremental pulling time correction calculation first matches the solidification time window corresponding to the high-risk shrinkage interval, and then calculates the optimal incremental pulling time for targeted shrinkage compensation using the optimal incremental pulling time correction formula. Based on this incremental pulling time, a set of directional solidification process parameters is generated, which is then substituted into the multi-physics coupling basic model to complete the simulation verification. After the verification is qualified, the optimal process parameter set is output.

[0026] In one embodiment, based on the spatial location of the high-risk zone, the solidification time characteristics of all nodes within the zone are matched from the transient multiphysics dataset. A 110s-250s solidification time window corresponding to this high-risk zone is defined, starting from 110s after casting when the earliest point reaches the liquidus temperature and ending at 250s after casting when the latest point reaches the solidus temperature. This window is the sole targeted time interval for the shrinkage compensation process optimization, ensuring that process adjustments only affect the solidification process of the high-risk zone and do not affect the normal solidification and single-crystal microstructure properties of other areas such as the blade body. Subsequently, the optimal incremental pulling time required to target and eliminate shrinkage porosity in the high-risk zone is quantitatively calculated using the optimal incremental pulling time correction formula. Based on this incremental pulling time, the constant pulling speed curve in the baseline directional solidification process is gradient-corrected. Within the targeted solidification time window of 110s-250s, the pulling speed is adjusted... The rate is gradually reduced to the optimal rate. By extending the pulling time within this window, the solidification front temperature gradient is increased to the optimal temperature gradient, narrowing the width of the mushy region to the optimal width, opening up the feeding channels between dendrites, eliminating isolated liquid phase regions, and achieving targeted suppression of micro-shrinkage. Simultaneously, based on the incremental pulling time, the heating zone temperature is increased and the cooling medium flow rate is increased to ensure the stability of the overall solidification temperature field of the blade during the pulling rate adjustment process, avoiding new solidification defects such as grain impurities and freckles caused by changes in the pulling rate. After the process parameter set is generated, it is substituted into the constructed multiphysics coupling basic model for verification solution. After verification and correction, the feature integral values ​​of the mushy region of all nodes in the high-risk interval are lower than the pre-calibrated low-risk threshold. The process parameter set is then determined to be lattice-bound, and the optimal process parameter set for the entire directional solidification process is output to ensure that the output process parameters can directly achieve the core objective of micro-shrinkage suppression.

[0027] Furthermore, The optimal incremental pull-out time correction formula is as follows: In the formula, To determine the optimal incremental pull time, This is the pre-calibrated correction factor for the feeding efficiency. This represents the integral value of the maximum pasty region characteristic within the high-risk range of the contraction process. This represents the maximum instantaneous width of the pasty region within the high-risk zone. The width of the critical paste-like region without shrinkage in the alloy.

[0028] This formula is based on the positive correlation between the severity of shrinkage risk and the need to improve shrinkage compensation capacity. It achieves precise quantitative control of shrinkage compensation process adjustment and completely abandons the traditional process adjustment method that relies on experience and trial and error in production. In one embodiment, The pre-calibrated DD6 alloy feeding efficiency correction factor is 0.008. It is pre-calibrated through the directional solidification feeding test of DD6 alloy. It is dimensionless and is used to correct the influence of the actual solidification process on the feeding effect by adjusting the pulling rate, so as to ensure that the formula calculation results are highly matched with the actual production conditions of the vacuum directional solidification furnace. The maximum integral value of the pasty region, 520 mm·s, within the high-risk range for shrinkage loosening represents the highest level of shrinkage loosening risk within this range. The maximum instantaneous mushy zone width within this high-risk range is 4.33 mm, representing the worst-case closed state of the feeding channel within this range. These two parameters together determine the basic requirements for improving feeding capacity, ensuring that process adjustments are precisely matched with the level of risk. The critical width of the non-shrinkage porosity pasty region for DD6 alloy is 3 mm. This width was pre-determined through the standard solidification test of DD6 alloy and serves as the core criterion for judging the shrinkage compensation effect. Substituting the above parameters into the formula, the optimal incremental pulling time is calculated. =0.008×520×(4.33 / 3)≈12s. The optimal incremental pulling time calculated by this formula can accurately match the shrinkage suppression requirements in the high-risk range. It avoids the problems of insufficient incremental pulling leading to inadequate shrinkage compensation and incomplete elimination of shrinkage, as well as the problems of excessive incremental pulling leading to reduced production efficiency and the introduction of other solidification defects.

[0029] Furthermore, In S4, the quality inspection data includes fluorescence penetrant detection data of the tenon grinding surface and metallographic microscopic analysis data within the tenon grinding allowance range; the fluorescence penetrant detection data includes at least the presence, spatial location, and quantity of linear fluorescence defects, and the metallographic microscopic analysis data includes at least the degree of aggregation, spatial distribution, and size of micro shrinkage.

[0030] In one embodiment, after the vacuum directional solidification preparation of the blade casting is completed according to the optimal process parameter set, a CNC forming grinder is used to perform precision grinding of the tenon part, removing a preset grinding allowance of 0.3mm, so that the tenon surface reaches the design surface roughness of Ra0.8μm and the dimensional accuracy requirement of IT5 level; then, fluorescence penetrant testing is carried out on the ground tenon surface, strictly in accordance with aerospace industry standards. The collected fluorescence penetrant testing data includes at least the presence or absence of linear fluorescence defects, the spatial location of the defects, and the length and number of defects. For example, in the verification batch, no linear fluorescence display with a length greater than 0.5mm was detected on the ground tenon surface. This data directly corresponds to the core defect that this invention aims to prevent and control, and can intuitively verify the actual application effect of the process scheme. Simultaneously, metallographic microscopy analysis was performed on the cross-sectional area corresponding to the 0.3mm grinding allowance of the tenon. The metallographic sample mounting, grinding, polishing, and chemical etching were completed according to standard procedures. Microscopic observation and quantitative analysis were completed using a metallographic microscope and image analysis system. Data on the degree of aggregation, spatial distribution, size, and quantity of micro-shrinkage porosity within the tenon grinding allowance range were collected. For example, no aggregated micro-shrinkage porosity was found within the tenon grinding allowance range, with only a very small number of diffusely distributed micropores smaller than 5μm in size. This data can verify the inhibition effect of micro-shrinkage porosity from the root of solidification. If the qualified standard is not met, the location and severity of the defect root cause can be identified, providing accurate feedback for subsequent reverse iterative correction and completely avoiding the blindness of iterative optimization.

[0031] Furthermore, In S4, the calculation parameters of the preceding steps are corrected by reverse iteration, including: correcting the shrinkage risk threshold based on the quality inspection data, correcting the shrinkage efficiency correction coefficient, correcting the boundary parameters of the multi-physics coupling basic model, and then re-executing the entire process loop from S1 to S4 until the quality inspection data meets the qualification standard.

[0032] In one embodiment, when the quality inspection data collected from the process verification batch shows that a 1.2mm linear fluorescence defect was detected on the ground surface of the second tooth root of the tenon, and the corresponding metallographic analysis revealed that there was aggregated micro-shrinkage porosity within the 0.3mm grinding allowance at this location, which did not meet the preset qualification standard, the system automatically initiated a reverse iterative correction process. First, the detected linear fluorescence defect location and the micro-shrinkage porosity aggregation area were spatially matched with the defined high-risk shrinkage porosity interval. It was found that this location was initially judged as a medium-risk interval, indicating a problem of missed judgment due to a lenient risk threshold setting. Subsequently, closed-loop correction of three core parameters was carried out based on the quality inspection data. One of them was to correct the shrinkage porosity risk judgment threshold. Based on the actual shrinkage porosity distribution detected by metallography and the characteristic integral value of the mushy area at the corresponding location, the high-risk threshold was lowered from 600mm·s to 450mm·s, and the low-risk threshold was lowered from 300mm·s to 200mm·s, thereby improving the accuracy of subsequent shrinkage porosity risk judgment and avoiding missed judgment of risk areas. The second is the correction coefficient for the feeding efficiency. Based on the severity of the actual defects, The value was increased from 0.008 to 0.01 to improve the accuracy of incremental pulling time calculation and ensure that the shrinkage compensation capacity is precisely matched with the shrinkage suppression requirements; Thirdly, the boundary parameters of the multiphysics coupling basic model are corrected. Based on the real-time temperature data of the equipment heating zone collected during actual production and the solidification temperature measurement data of the thermocouples embedded in the casting, the heat transfer coefficient between the shell and the casting is increased to optimize the thermal boundary conditions of the model, improve the accuracy of the solidification process simulation calculation, and ensure that the model output is consistent with the actual solidification process. After the parameter correction is completed, the system automatically re-executes the full process cycle from S1 to S4, recalculates the optimal incremental pulling time to 18s, generates the corrected process parameter set, conducts production verification again, and finally the batch test results meet the qualified standards, realizing closed-loop optimization of the entire process.

[0033] Furthermore, The qualification criteria are that there are no linear fluorescence defects on the surface of the tenon grinding and no aggregated micro shrinkage porosity within the tenon grinding allowance. When the qualification criteria are met, the current optimal process parameter set is solidified and stored in the process database for mass production of the same type of blade.

[0034] Furthermore, A root cause control system for fluorescence defects after turbine blade grinding includes: The basic model building module receives the solidification feature parameters of the tenon and tooth, constructs and solves the directional solidification multiphysics coupling basic model, and outputs the transient multiphysics basic dataset of the tenon and tooth part throughout the entire solidification cycle. The shrinkage risk assessment module takes the transient multiphysics field basic dataset as input, and outputs a set of parameters for high-risk shrinkage intervals within the tenon grinding allowance range by quantizing the width of the smeared region. The process parameter generation module takes the parameter set of the high-risk shrinkage zone as input, and through the optimal incremental pulling time correction calculation, outputs the optimal process parameter set of the entire directional solidification process that has passed the simulation verification. The closed-loop control execution module uses the optimal process parameter set as input to control the directional solidification equipment to execute the process, collects quality inspection data after tenon grinding, and completes process solidification or reverse iteration to correct the calculation parameters of other functional modules based on the inspection results, thereby realizing closed-loop control of the entire process.

[0035] It is understood that the above embodiments are merely exemplary implementations used to illustrate the principles of the present invention, and the present invention is not limited thereto. For those skilled in the art, various modifications and improvements can be made without departing from the spirit and essence of the present invention, and these modifications and improvements are also considered to be within the scope of protection of the present invention.

Claims

1. A method for controlling the root cause of fluorescence defects after grinding turbine blades, characterized in that, include: S1. By obtaining the solidification characteristic parameters of the tenon, constructing and solving the directional solidification multiphysics coupling basic model, the transient multiphysics basic dataset of the tenon part during the entire solidification cycle is obtained. S2. Based on the transient multiphysics field dataset, perform quantitative calculation of the width of the mushy region to obtain the parameter set of the high-risk interval of shrinkage within the tenon grinding allowance range; S3. Based on the parameter set of the high-risk shrinkage zone, the optimal incremental pulling time correction calculation is performed to obtain the optimal process parameter set of the entire directional solidification process that has been verified by simulation. S4. With the optimal set of process parameters as the target, control the directional solidification equipment to execute the process, collect the quality inspection data after the tenon grinding, and complete the process solidification or reverse iterative correction of the calculation parameters of the preceding steps based on the inspection results, so as to realize the closed-loop control of the whole process.

2. The method for controlling the root cause of fluorescence defects after grinding turbine blades according to claim 1, characterized in that, In S1, the solidification characteristic parameters of the tenon include the three-dimensional digital model of the turbine blade, the grinding allowance parameters of the tenon design, the thermophysical property parameters of the alloy used in the blade, and the controllable process boundary parameters of the directional solidification equipment. When constructing the multiphysics coupling basic model, the spatial range corresponding to the grinding allowance of the tenon is locally densified into a mesh. The transient multiphysics basic dataset obtained by solving the problem includes at least the full-cycle transient temperature, solid-liquid phase fraction, solidification front temperature gradient, and solidification rate data of each mesh node in the tenon part.

3. The method for controlling the root cause of fluorescence defects after grinding turbine blades according to claim 1, characterized in that, In S2, the quantization calculation of the width of the mushy region includes two-level quantization calculation. First, the instantaneous width of the mushy region of each node within the grinding allowance range of the tenon tooth is obtained through the instantaneous mushy region width calculation formula. Then, the shrinkage loosening tendency feature value of each node is obtained through the mushy region feature integral value calculation formula. Based on the pre-calibrated shrinkage loosening risk threshold, the risk level classification and high-risk interval clustering are completed, and the high-risk interval parameter set of shrinkage loosening is output.

4. The method for controlling the root cause of fluorescence defects after grinding turbine blades according to claim 3, characterized in that, The formula for calculating the width of the instantaneous pasty region is: ; The formula for calculating the integral value of the mushy region feature is as follows: ; In the formula, Let be the instantaneous mushy region width of the i-th node within the tenon grinding allowance at time t. This is the liquidus temperature of the alloy. This refers to the solidus temperature of the alloy. Let be the solidification front temperature gradient of the i-th node at time t; Let be the integral value of the mushy region feature of the i-th node. Let be the moment when the temperature of the i-th node drops to the liquidus temperature. This is the moment when the temperature of the i-th node drops to the solidus temperature.

5. The method for controlling the root cause of fluorescence defects after grinding turbine blades according to claim 1, characterized in that, In S3, the optimal incremental pulling time correction calculation first matches the solidification time window corresponding to the high-risk shrinkage interval, and then calculates the optimal incremental pulling time for targeted shrinkage compensation using the optimal incremental pulling time correction formula. Based on this incremental pulling time, a set of directional solidification process parameters is generated, which is then substituted into the multi-physics coupling basic model to complete the simulation verification. After the verification is qualified, the optimal process parameter set is output.

6. The method for controlling the root cause of fluorescence defects after grinding turbine blades according to claim 5, characterized in that, The optimal incremental pull-out time correction formula is as follows: In the formula, To determine the optimal incremental pull time, This is the pre-calibrated correction factor for the feeding efficiency. This represents the integral value of the maximum pasty region characteristic within the high-risk range of the contraction process. This represents the maximum instantaneous width of the pasty region within the high-risk zone. The width of the critical paste-like region without shrinkage in the alloy.

7. The method for controlling the root cause of fluorescence defects after grinding turbine blades according to claim 1, characterized in that, In S4, the quality inspection data includes fluorescence penetrant detection data of the tenon grinding surface and metallographic microscopic analysis data within the tenon grinding allowance range; the fluorescence penetrant detection data includes at least the presence, spatial location, and quantity of linear fluorescence defects, and the metallographic microscopic analysis data includes at least the degree of aggregation, spatial distribution, and size of micro shrinkage.

8. The method for controlling the root cause of fluorescence defects after grinding turbine blades according to claim 1, characterized in that, In S4, the calculation parameters of the preceding steps are corrected by reverse iteration, including: correcting the shrinkage risk threshold based on the quality inspection data, correcting the shrinkage efficiency correction coefficient, correcting the boundary parameters of the multi-physics coupling basic model, and then re-executing the entire process loop from S1 to S4 until the quality inspection data meets the qualification standard.

9. The method for controlling the root cause of fluorescence defects after grinding turbine blades according to claim 8, characterized in that, The qualified criteria are that there are no linear fluorescent defects on the surface of the tenon grinding and no aggregated micro shrinkage within the tenon grinding allowance. When the qualification criteria are met, the current optimal process parameter set is fixed and stored in the process database for mass production of the same type of blade.

10. A root cause control system for fluorescence defects after turbine blade grinding, characterized in that, include: The basic model building module receives the solidification feature parameters of the tenon and tooth, constructs and solves the directional solidification multiphysics coupling basic model, and outputs the transient multiphysics basic dataset of the tenon and tooth part throughout the entire solidification cycle. The shrinkage risk assessment module takes the transient multiphysics field basic dataset as input, and outputs a set of parameters for high-risk shrinkage intervals within the tenon grinding allowance range by quantizing the width of the smeared region. The process parameter generation module takes the parameter set of the high-risk shrinkage zone as input, and through the optimal incremental pulling time correction calculation, outputs the optimal process parameter set of the entire directional solidification process that has passed the simulation verification. The closed-loop control execution module uses the optimal process parameter set as input to control the directional solidification equipment to execute the process, collects quality inspection data after tenon grinding, and completes process solidification or reverse iteration to correct the calculation parameters of other functional modules based on the inspection results, thereby realizing closed-loop control of the entire process.

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