A method for correcting micro convex deformation of a thin-walled part in a sealed cavity based on ultrasonic impact

Abstract

The application relates to the technical field of surface treatment, and discloses a micro convex deformation correction method for a thin-walled sealed cavity part based on ultrasonic impact. The method comprises the following steps: obtaining an entity model through optical scanning, comparing a design model to obtain a deformation area and a deformation amount, importing a finite element software to simulate correction, determining a critical moving speed of ultrasonic impact, correcting a model by using a physical feature part, determining reference correction parameters and other area correction parameters based on a moving speed coefficient, and finally iteratively correcting to reach a standard according to the deformation amount from large to small; compared with the prior art, the method can accurately position and quantify deformation, combines simulation and physical objects to determine differential parameters, dynamically optimizes through real-time feedback, realizes green and efficient correction of micro regions, non-uniformity and large size deformation, and provides a feasible means for repairing and assembling key parts in the fields of aviation and aerospace.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of surface treatment, in particular to a micro convex deformation correction method for sealed cavity thin-walled parts based on ultrasonic impact. BACKGROUND

[0002] As a key part of enclosing a closed space through a thin-walled structure, the sealed cavity thin-walled part is widely used in the fields of aerospace, automobile and other high-end manufacturing due to its lightweight and high integration characteristics. Influenced by material characteristics and processing flow, the part is prone to non-uniform deformation, especially micro regional convex deformation (deformation amount can reach large size level in some scenarios), during cutting, heat treatment and service repair (such as welding repair of an aircraft engine guide). Such deformation will directly lead to insufficient assembly precision of the part, and even cause product stoppage and scrap, which seriously restricts production efficiency and equipment reliability.

[0003] In the existing shape correction technology, mechanical shape correction and thermal shape correction have limited correction effect on the micro regional convex deformation of the sealed cavity thin-walled part. Shot peening and laser impact can be used for shape correction of some thin-walled parts, but due to the structural closure and interference of the sealed cavity, they cannot effectively act on the convex deformation area. Although ultrasonic impact technology has been maturely applied in the field of material strengthening, its application in the fields of forming and shape correction is still in the exploratory stage. The existing few shape correction related applications can only achieve preliminary adjustment of macro deformation, and cannot provide accurate and controllable correction scheme for the micro regional non-uniform convex deformation of the sealed cavity thin-walled part. SUMMARY

[0004] In order to correct the micro regional convex deformation of the sealed cavity thin-walled part which cannot be repaired by mechanical shape correction, thermal shape correction, shot peening and laser impact, the present application provides a micro convex deformation correction method for sealed cavity thin-walled parts based on ultrasonic impact. The present application can quickly and accurately locate the micro convex deformation area and quantify the deformation amount, determine the differentiated shape correction parameters suitable for different deformation areas by combining simulation and physical verification, greatly improve the pertinence and effectiveness of the correction, and then adjust the subsequent operation according to the real-time feedback after each shape correction, realize the dynamic optimization of the correction process, especially in the complex deformation scene of "micro region, non-uniformity and large size", realize green and efficient correction, and provide a feasible technical means for key part repair and assembly in the fields of aerospace and other fields.

[0005] The present application is implemented by the following technical solutions:

[0006] A micro convex deformation correction method for sealed cavity thin-walled parts based on ultrasonic impact, comprising the following steps:

[0007] Step 1: scanning the sealed cavity thin-walled part by an optical scanning device, converting the scanning data into a solid model, comparing the solid model with a design model to obtain multiple non-uniform micro convex deformation regions Ni, and obtaining deformation amounts Di of each region, wherein i = 1, 2…m, and m is the number of deformation regions;

[0008] Step 2: importing the solid model into a finite element simulation software, defining the model material and material performance parameters, setting the ultrasonic impact parameters and simulating the correction, and determining the critical ultrasonic impact moving speed that can make the convex deformation have a concave trend;

[0009] Step 3: preparing a physical feature part adapted to the solid model, correcting the simulation model of step 2 by ultrasonic impact, determining the reference correction parameter Up at the maximum deformation max(Di), taking the ratio of the deformation amount to the maximum deformation as the moving speed coefficient Vp for other regions, and correcting the reference correction parameter Up based on the moving speed coefficient Vp to obtain the correction parameter of the corresponding region;

[0010] Step 4: in the order of deformation amount from large to small, sequentially performing ultrasonic impact correction on each deformation region based on the corresponding correction parameter obtained in step 3, re-measuring the deformation amount of each region after each correction, and iteratively performing the correction operation according to the re-measurement result until the deformation amounts of all regions meet the assembly technical requirements.

[0011] In the present application, step 1 precisely locates multiple non-uniform micro convex deformation regions and obtains deformation amounts by optical scanning and model comparison, providing accurate deformation data basis for subsequent correction and avoiding errors of traditional detection methods; step 2 determines the critical ultrasonic impact moving speed by finite element simulation, clearly defines the key parameter boundary that can produce effective correction effect (make the convex deformation have a concave trend), and solves the problem that blind setting of ultrasonic impact parameters may lead to ineffective correction or aggravated deformation; step 3 combines simulation and actual operation by correcting the simulation model with the physical feature part and determining the reference correction parameter and regional correction parameter, realizes differentiated parameter adaptation of different deformation regions through the moving speed coefficient, and ensures the pertinence of correction; step 4 iteratively corrects and re-measures in the order of deformation amount from large to small, utilizes the characteristic that “one correction affects the deformation of other regions” in ultrasonic impact correction, gradually optimizes the overall deformation through dynamic adjustment, and finally makes all regions meet the assembly requirements, breaking through the limitations of existing technologies such as mechanical correction, thermal correction, shot blasting and laser impact on the correction of convex deformation of the sealed cavity thin-walled part, and especially suitable for the correction of non-uniform micro region convex deformation of the sealed cavity thin-walled part in the process of machining, heat treatment and repair in the field of aerospace, effectively avoiding the scrapping of parts due to excessive deformation, and realizing green manufacturing and cost reduction and efficiency improvement.

[0012] Further, the optical scanning device is a blue light three-dimensional scanner, which can perform high-precision scanning on the sealed cavity thin-walled part, convert the scanning data into a solid model, accurately identify multiple non-uniform micro convex deformation regions Ni and obtain the deformation amounts Di of the regions, provide accurate initial deformation data basis for subsequent shape correction work, and after obtaining the deformation amounts Di, the deformation regions and the deformation amounts need to be re-measured by high-precision measuring tools, which can further verify the reliability of the deformation regions and the deformation amounts, avoid the influence of possible errors in single scanning on the accuracy of subsequent simulation simulation, parameter determination and shape correction operation, and ensure that the real and reliable basis is provided for the entire ultrasonic impact correction process from the deformation detection stage.

[0013] Further, in step 2, the ultrasonic impact parameters include vibration frequency, amplitude, applied load, row distance and moving speed. By specifying these parameters, the simulation can be more consistent with the actual ultrasonic impact scene, laying a foundation for determining the critical moving speed of ultrasonic impact that can make the convex deformation have a concave trend, and ensuring the scientificity and accuracy of the simulation simulation.

[0014] Further, in step 2, the simulation shape correction changes only the moving speed by fixing the vibration frequency, amplitude, applied load and row distance parameters, so as to determine the critical moving speed of the ultrasonic wave. By controlling the variable, the influence of other parameters on the shape correction effect is excluded, the correlation between the key parameter of moving speed and the concave trend of convex deformation is accurately positioned, and the critical moving speed that can achieve the shape correction effect (i.e. produce a concave trend) is efficiently determined.

[0015] Further, in step 2, when the ultrasonic impact parameter simulation shape correction is performed, the values of the parameters are determined based on the material properties and deformation degree of the sealed cavity thin-walled part to be corrected, so that the simulation is more consistent with the actual situation of the specific part. The simulation process needs to record the residual stress distribution and deformation trend change under different moving speeds synchronously, so as to clearly present the correlation between the moving speed and the residual stress and the deformation trend. This not only provides data support for the determination of the critical moving speed (i.e. the speed threshold that makes the convex deformation have a concave trend), but also provides a reference basis for correcting the simulation model with physical features in the subsequent process, and ensures the consistency of the simulation model and the actual shape correction scene.

[0016] Further, in step 3, the moving speed of the reference shape correction parameter Up is greater than the critical moving speed of the ultrasonic impact determined in step 2, which can ensure the correctness of the shape correction direction. If it is not satisfied, one of the ultrasonic impact parameters is adjusted, and steps 2 and 3 are repeated, so as to determine the adaptive critical moving speed and the reference shape correction parameter again, form a closed-loop logic of parameter adjustment, and avoid shape correction failure caused by improper initial parameter setting.

[0017] Further, in step 3, the correction parameter of other areas is the product of the moving speed coefficient Vp and the reference correction parameter Up, and the corresponding correction parameter is calculated based on the reference correction parameter Up determined at the maximum deformation and the ratio of the deformation of other areas to the maximum deformation, so that the ultrasonic impact strength of each deformation area matches the deformation degree thereof, and the accuracy of the correction is ensured.

[0018] Further, the iterative correction in step 4 is specifically as follows:

[0019] Step 41: Since the correction at a certain position in the ultrasonic impact correction will affect the deformation degree of other areas, the reference correction parameter Up is used to correct the maximum deformation max(Di);

[0020] Step 42: After the first correction, the deformation of each area N2i is measured to obtain D2i, and the ratio of the new maximum deformation max(D2i) to the initial maximum deformation max(Di) is taken as the moving speed coefficient Vp2, and the parameter obtained by Vp2xUp is used to correct max(D2i), and through iteration, the mutual influence in the correction process can be used to gradually reduce the overall deformation, and the problems of local overcorrection or undercorrection caused by disordered correction are avoided;

[0021] Step 43: Repeat step 42, and the iterative method can dynamically adjust the operation by real-time feedback of deformation changes through re-measurement, so that the deformation of all areas gradually converges to meet the technical requirements, and the problem that the sealed cavity thin-walled part may be scrapped due to non-uniform convex deformation at multiple positions is effectively solved.

[0022] Further, in step 4, the optical scanning device and the high-precision gauge used in the re-measurement process are the same as those in step 1, which are used to ensure the consistency and accuracy of the deformation measurement.

[0023] Further, the micro-convex deformation of the sealed cavity thin-walled part is non-uniform micro-area convex deformation generated in the processing, heat treatment or service repair process, and the deformation amount includes large-size convex deformation scenarios.

[0024] Compared with the prior art, the present application has the following advantages and beneficial effects:

[0025] The mechanical correction, thermal correction in the prior art has limited effect on the micro-region convex deformation correction of the thin-walled part of the sealed cavity, and the shot blasting, laser impact and other technologies can correct the concave deformation or open deformation, but cannot deal with the micro-region convex deformation of the sealed cavity and other large interference parts, and the present application is specially used for the non-uniform micro-region convex deformation of the thin-walled part of the sealed cavity generated in the processing, heat treatment and service repair process, breaks through the application limitation of the prior art, and can effectively correct the deformation which cannot be repaired by traditional methods; the present application accurately obtains the deformation region and deformation amount through optical scanner scanning combined with high-precision gauge re-measurement, and determines the critical moving speed of ultrasonic impact with the help of finite element simulation, then corrects the model of the physical feature part and determines the reference correction parameters, at the same time, the moving speed coefficient is used to realize the differentiated parameter adaptation of different deformation regions, finally, the deformation correction is iterated from large to small according to the deformation amount, and re-measurement is performed, forming a complete closed loop of "detection-simulation-parameter optimization-iterative correction", which ensures the accurate and controllable correction process, and can realize the fine adjustment of the micro-region deformation. BRIEF DESCRIPTION OF DRAWINGS

[0026] The drawings described herein are used to provide further understanding of the embodiments of the present application, constitute a part of the present application, and do not constitute a limitation on the embodiments of the present application. In the drawings:

[0027] Figure 1 The deformation correction flowchart provided by the present application is shown in the figure;

[0028] Figure 2 The convex deformation schematic diagram of the thin-walled part of the sealed cavity provided by the embodiment of the present application is shown in the figure;

[0029] Figure 3 The measurement point distribution schematic diagram when using ultrasonic impact to perform ultrasonic impact test on the thin-walled part of the sealed cavity is shown in the figure;

[0030] Figure 4 The measurement point region distribution schematic diagram of the thin-walled part of the sealed cavity when the iterative correction method of the present application is used is shown in the figure. DETAILED DESCRIPTION

[0031] In order to make the purpose, technical scheme and advantages of the present application more clear and explicit, the present application is further described in detail below in combination with embodiments and drawings, and the schematic embodiments of the present application and their descriptions are only used to explain the present application, and do not constitute a limitation on the present application.

[0032] Embodiment 1

[0033] The present embodiment 1 provides a micro-convex deformation correction method for the thin-walled part of the sealed cavity based on ultrasonic impact, as shown in the figure, the correction process is as follows: Figure 1

[0034] ​First, step 1 is the deformation detection stage: the operator uses a blue light three-dimensional scanner to scan the sealed cavity thin-walled part, converts the scanned point cloud data into a complete solid three-dimensional model, and then imports the solid model and the original design model into the comparison software. Through point-by-point deviation analysis, all non-uniform micro convex deformation areas (marked as Ni, i = 1, 2…m, m is the number of deformation areas) are located, and the deformation of each large size deformation area (marked as Di, i = 1, 2…m, m is the number of deformation areas) is quantified. To ensure data reliability, high-precision micrometer or three-coordinate measuring instrument is used to retest the most obvious deformation area and the corresponding deformation, if the deviation between the retest value and the scanning value is within 0.01mm, the deformation data is effective, otherwise it needs to be rescaned.

[0035] Second, step 2 is the simulation parameter determination stage: the verified solid model is imported into the finite element simulation software, and the material and related material performance parameters (such as the elastic modulus, Poisson's ratio, yield strength and other performance parameters of aluminum alloy and titanium alloy) of the solid model are defined. Then, according to the existing ultrasonic impact process, set the basic parameters of ultrasonic impact, vibration frequency 20KHz, amplitude 20μm, load 500N, line spacing 0.03mm. After fixing these parameters, only change the moving speed of the impact head (range 5-1000mm / s) to simulate the correction effect at different speeds. When the simulation result shows that the convex deformation area begins to appear concave trend, record the moving speed at this time as the critical moving speed of ultrasonic impact. When the impact effect exceeds the critical value, it will produce convex trend, that is, the deformation of the deformation area increases, which is a negative effect. Therefore, this speed is the highest threshold of subsequent correction without aggravating deformation.

[0036] Then step 3 is the correction parameter adaptation stage: according to the deformation characteristics of the solid model, a physical feature part with the same convex deformation characteristics is processed with the same material. The simulation model obtained in the above step is corrected by ultrasonic impact. Specifically, the correction requirement at the maximum deformation max(Di) is used to determine the reference correction parameter Up, the deformation degree area is calculated according to the ratio of its deformation Di to the maximum deformation max(Di) to obtain the moving speed coefficient Vp, and the correction parameter of the corresponding area is obtained by "Vp x Up" (such as the deformation of a certain area is 60% of the maximum deformation, then its moving speed is 60% of the reference speed). Among them, the reference correction parameter Up should ensure that the moving speed is greater than the critical moving speed of the modified model, otherwise adjust one of the ultrasonic impact parameters (frequency, amplitude, load, line spacing), and repeat steps 2 and 3 until the requirements are met.

[0037] The last step 4 is an iterative correction phase: for the deformation of multiple non-uniform micro-regions of large size, the ultrasonic impact parameters are fixed, and different correction effects are achieved by controlling the moving speed coefficient Vp and the corresponding region. Since the ultrasonic impact correction method utilizes the plastic deformation generated instantaneously, the deformation degree of other places will be reduced when correction is performed at a certain place, therefore, in this embodiment, the deformation is first corrected at the place with the largest deformation max (Di) using the reference correction parameter Up according to the order from large to small; after the first correction, the deformation amount of each region N2i is measured to obtain D2i, and the ratio of the new maximum deformation amount max (D2i) to the initial maximum deformation amount max (Di) is taken as the moving speed coefficient Vp2, and the parameters obtained by Vp2xUp are used to correct max (D2i); after the second correction, the deformation amount of each region N3i is measured to obtain D3i, and the ratio of the new maximum deformation amount max (D3i) to the initial maximum deformation amount max (Di) is taken as the moving speed coefficient Vp3, and the parameters obtained by Vp3xUp are used to correct max (D3i); in this way, the deformation from large to small and the corresponding position are iteratively corrected until the technical condition requirements are met. In this way, the deformation of all regions is controlled within the assembly requirements, and the correction is finally completed.

[0038] Example 2

[0039] The following is a correction method for the micro-region convex deformation of a sealing cavity thin-walled part of a certain guide, and the specific implementation process is as follows:

[0040] After the repair welding of the aircraft engine guide, as shown in Figure 2 , micro convex deformation out-of-tolerance occurs near the welding area, with a maximum deformation of 1.6 mm, which can only be scrapped if it cannot be corrected. At this time, a blue light three-dimensional scanner is used to scan the guide comprehensively, and the data obtained by scanning is converted into an accurate solid model. Then, the solid model is carefully compared with the original design model of the guide, and the deformed regions are clearly identified with the help of professional analysis software, and are divided into 1# to 8# a total of 8 micro convex deformation zones, as shown in Figure 3 and Figure 4 . By measuring the axial distance from each region to the bottom surface, the maximum axial distance value is determined to be 1243.25 mm (corresponding to the maximum deformation zone), and the minimum is 1242.95 mm, thereby quantifying the deformation of each region. In order to ensure the accuracy of the data, high-precision measuring tools such as three-coordinate measuring machines are used to re-measure the key deformation regions and deformation amounts, so as to ensure that the measurement error is within a very small range, and to provide a reliable data basis for subsequent correction work.

[0041] The built entity model is imported into ABAQUS finite element simulation software, and the material and various performance parameters of the guide are input, such as the accurate setting of the elastic modulus, Poisson's ratio and other key parameters for a specific high-temperature alloy material. The related parameters of ultrasonic impact are preliminarily set, including vibration frequency, amplitude, applied load, line spacing, etc. During the sizing simulation process, the parameters of vibration frequency, amplitude, applied load and line spacing are fixed, and only the moving speed is changed (the moving speed is set within a certain range, such as 100-800 mm / min). By continuously simulating the sizing effect under different moving speeds, the stress distribution is analyzed in depth, and finally it is found that when the moving speed reaches 300 mm / min, the convex deformation region begins to show a concave trend, so the critical moving speed of ultrasonic impact is determined to be 300 mm / min.

[0042] According to the entity model converted from the scanning data, a physical feature part with corresponding deformation characteristics is manufactured, and the simulation model is corrected by ultrasonic impact. Then, according to the correction requirement at the maximum deformation position, the reference sizing parameter Up is determined, wherein the moving speed is set to 500 mm / min, which is greater than the critical moving speed 300 mm / min determined before, and the vibration frequency is 20 kHz, the amplitude is 0.02 mm, the applied load is 500 N, and the line spacing is 0.03 mm. For other deformation regions, the moving speed coefficient Vp is calculated according to the ratio of the deformation amount to the maximum deformation amount. For example, if the deformation amount of a certain region is 0.8 mm, the moving speed coefficient Vp = 0.8 ÷ 1.6 = 0.5, then the moving speed corresponding to the region is 500 × 0.5 = 250 mm / min, and the rest of the vibration frequency, amplitude, applied load and line spacing parameters remain consistent with the reference sizing parameter Up, so as to realize the adaptation of sizing parameters of different deformation regions.

[0043] According to the order of deformation amount from large to small, first, the maximum deformation area (1#) is subjected to ultrasonic impact correction using the reference correction parameter Up. During the impact process, the impact head moves along the circumferential direction at a uniform speed, and the impact effect is applied to the deformation area. After the first correction, immediately use the blue light scanner to retest each area, and find that the deformation amount of 1# is reduced to 0.5mm, at this time the new maximum deformation area becomes 2# (deformation amount is 1.4mm). According to the ratio of the new maximum deformation amount to the initial maximum deformation amount, the moving speed coefficient Vp2 =1.4 ÷ 1.6 = 0.875 is calculated, and then the correction parameter is updated, and the moving speed is adjusted to 500 × 0.875 = 437.5mm / min. Then, the updated parameter is used to correct the 2# area, and after correction, the deformation amount is reduced to 0.3mm. In this way, the 3# to 8# areas are sequentially corrected, and the parameter is adjusted according to the new maximum deformation amount after each correction. After several rounds of iterative correction, the axial distances of all areas are 1241.93mm (maximum) and 1241.90mm (minimum) respectively, which meet the technical requirement of less than 1241.65mm, and the correction of the guider is successfully completed.

[0044] Through the above implementation process, the effectiveness and accuracy of the sealing cavity thin-walled part micro-protrusion deformation correction method based on ultrasonic impact in practical application are fully demonstrated, which can effectively solve the non-uniform micro-regional protrusion deformation problem of the sealing cavity thin-walled part in the process of machining, heat treatment or service repair, especially for the repair of key components such as aircraft engine guider.

[0045] The above specific embodiments further illustrate the purpose, technical solutions and beneficial effects of the present application. It should be understood that the above description is only a specific embodiment of the present application and does not limit the protection scope of the present application. Any modification, equivalent replacement, improvement, etc. within the spirit and principles of the present application shall be included in the protection scope of the present application.

Claims

1. A method for micro-bulge deformation correction of a thin-walled part of a sealed cavity based on ultrasonic impact, characterized in that, Comprising the following steps: Step 1: globally scanning the sealed cavity thin-walled part with structural closure by an optical scanning device, converting the scanning data into a solid model, comparing the solid model with the design model, and obtaining multiple non-uniform micro convex deformation regions Ni and deformation amounts Di (i=1, 2…m, m is the number of deformation regions) of each region, the micro convex deformation is a non-uniform micro region convex deformation generated in the process of machining, heat treatment or service repair, and contains a large size convex deformation scene; then re-measuring the deformation region and deformation amount by a high-precision gauge to ensure that the deviation between the re-measured value and the scanned value is within 0.01mm; Step 2: importing the re-measured and verified solid model into a finite element simulation software, defining the model material and material performance parameters, setting the ultrasonic impact parameters including vibration frequency, amplitude, applied load, row distance and moving speed; fixing the vibration frequency, amplitude, applied load and row distance parameters, only changing the moving speed to perform the correction simulation, simultaneously recording the residual stress distribution and deformation trend change under different moving speeds to determine the ultrasonic impact critical moving speed that can make the convex deformation have a concave trend; Step 3: preparing a physical feature part adapted to the solid model, correcting the simulation model of step 2 by ultrasonic impact, and determining the reference correction parameter Up at the maximum deformation max(Di), the moving speed of the reference correction parameter Up is greater than the ultrasonic impact critical moving speed determined in step 2, if not, adjust one of the ultrasonic impact parameters and repeat steps 2 and 3; other regions take the ratio of deformation amount Di to maximum deformation max(Di) as the moving speed coefficient Vp, and obtain the correction parameters of the corresponding regions through Vp×Up; Step 4: according to the order of deformation amount from large to small, sequentially performing ultrasonic impact correction on each deformation region based on the corresponding correction parameters obtained in step 3, re-measuring the deformation amount of each region after each correction by the optical scanning device and high-precision gauge in step 1, and iteratively performing the correction operation according to the re-measured results until all region deformation amounts meet the assembly technical requirements.

2. The method according to claim 1, wherein, The optical scanning device is a blue light three-dimensional scanner.

3. The method according to claim 1, wherein, In step 2, when the ultrasonic impact parameter simulation correction is performed, the values of the parameters are determined based on the material properties and deformation degree of the sealed cavity thin-walled part to be corrected, and the simulation process needs to record the residual stress distribution and deformation trend change under different moving speeds.

4. The method according to claim 1, wherein, The iterative correction in step 4 is specifically: Step 41: correcting the maximum deformation max(Di) with the reference correction parameter Up; Step 42: re-measuring the deformation amount of each region N2i after the first correction to obtain D2i, taking the ratio of the new maximum deformation max(D2i) to the initial maximum deformation max(Di) as the moving speed coefficient Vp2, and performing correction on max(D2i) by the parameters obtained through Vp2×Up; Step 43: repeat step 42 until the size meets the technical requirements.

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