A method for judging the foreign object damage without repair based on historical data
Through the repair-free judgment method based on historical data, combined with industrial endoscopes and database comparison, the problem of inaccurate judgment of external objects in the aero engine blades is solved, the accuracy of judgment and the utilization rate of the blades is improved, and the maintenance cost is reduced.
Patent Information
- Application Number
- CN202110231072.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2021-03-02
- Publication Date
- 2024-12-17
- Estimated Expiration
- 2041-03-02
AI Technical Summary
The existing methods for determining external damage of aircraft engine blades are not accurate enough, resulting in high maintenance costs and lack of clearly defined damage types and complex damage handling capabilities in the maintenance manual.
Using a repair-free judgment method based on historical data, the blade damage information is captured through industrial endoscopes, combined with the available limits and database comparison of the maintenance manual, the size and structural similarity of the damage are judged, and whether it is repair-free is determined.
It improves the accuracy and utilization rate of blade damage judgment, reduces maintenance costs, and ensures safety and effective use of blades.
Smart Images
Figure CN113160127B_ABST
Abstract
Description
Technical Field
[0001] The invention relates to a damage identification technology method in the process of aircraft engine blade overhaul, and belongs to the field of aircraft engine blade overhaul and maintenance. Background Art
[0002] A series of external hard objects such as metal, gravel, sand, etc. will be sucked into the airflow during the operation of the aircraft engine, and collide with the high-speed rotating blades in the engine to form damage such as notches, pits and tears. This is called external non-damage or hard object damage, referred to as FOD. For this kind of unavoidable damage, engine designers often design it with a certain damage tolerance to accommodate a certain degree of damage. During the use of aircraft engines, great consideration must be given to the combat readiness and safety of the engine. After the fan or compressor blades are damaged by foreign objects, it is very likely that the blades will be replaced directly, which makes the maintenance cost of the blades or the engine very high.
[0003] At present, there are few studies related to FOD. Most maintenance manuals for newly developed engines refer to or directly transfer maintenance manuals of existing engines. At the same time, due to the lack of experience in field use of engines and the development of maintenance manuals, the determination of the usable limit itself has certain uncertainties. In the maintenance manual, the usable limits of damage are defined according to the leading edge, trailing edge, blade tip, and blade root of the blade. Each area is classified into types such as cracks, notches, pits, and missing blade tip materials. Each type has an usable limit based on the depth of damage. In actual work, due to different loads and the dispersion of impact, the damage will present a variety of complex situations. The slight size changes of the damage and the combination of multiple damages will make it impossible to find the corresponding type in the maintenance manual. In order to ensure safety, it can only be repaired or scrapped. Therefore, the inaccuracy of the foreign object damage judgment method based on the usable limit of the maintenance manual makes the blade unable to meet sufficient utilization. Therefore, a judgment method based on historical data is added to form a database to add the previous judgment of complex damage situations. New damage that cannot be accurately defined in the maintenance manual is compared with the database to obtain auxiliary definitions, which is convenient for better judgment on whether to exempt repairs.
[0004] In modern technology, the rapid development of machine vision has led to a rapid improvement in image recognition and processing technology. On many large mechanical equipment that is difficult to disassemble, image recognition can quickly determine the location of damage, allowing maintenance personnel to complete maintenance work without disassembling. In the identification of foreign object damage based on historical data, the database can integrate various factors and make more efficient comparisons to improve the accuracy of identification. Summary of the invention
[0005] The purpose of the present invention is to provide a method for determining whether a blade is maintenance-free by taking into account available limits and historical data, so as to solve the problem that the current method for determining whether a blade is maintenance-free is not accurate enough and the blade maintenance cost is high.
[0006] To achieve the above object, the technical solution adopted by the present invention is:
[0007] A method for judging the foreign object damage without repair based on historical data comprises the following steps:
[0008] (1) Using an industrial endoscope to capture the location of foreign object damage on the inspected blade based on the blade root, and identify the size and type of the foreign object damage to form a data set;
[0009] (2) According to the theory of usable limit in the maintenance manual, the blade foreign object damage in the data set obtained in step (1) is judged. If the size of the foreign object damage meets the maximum usable limit, no maintenance is required;
[0010] (3) If the size of the damage does not meet the maximum available limit, a decision is made based on experience from historical data;
[0011] (4) If it is found in the empirical judgment results of historical data that the target FOD and the historical FOD meet the two similarity conditions of size and structure, and if the historical FOD has not failed in operation, it is considered that the target FOD will not fail in future operation, and the blade does not need to be repaired;
[0012] (5) If there is no clear definition in the maintenance manual and the similarity conditions are not met in the historical data comparison, the target foreign object damage is considered to be unqualified, and the failure location and judgment criteria must be given and recorded.
[0013] In the step (1), the industrial endoscope probe is inserted into the interior of the engine to collect blade image information, and the position of various damages on the blade based on the blade root is determined based on the pixel distribution, brightness and color in the image information, and the position is converted into a digital signal. The digital signal is processed by a computer to extract the size characteristics of the foreign object damage, and the size characteristics include depth, area and angle.
[0014] In the step (2), the foreign object damage on the blade is divided into zones according to the location where the foreign object damage occurs, and then the foreign object damage to the blade in the data group is judged based on the available limits in the maintenance manual. The judgment criteria for the foreign object damage to the blade are the following three basic dimensional parameters: depth, width, and arc radius.
[0015] In the step (3), the step of making a judgment based on the experience of historical data is as follows: coordinate classification and partitioning of the blade foreign object damage information to obtain the location information of the foreign object damage; based on the location information, calling up the damage information at the same location in the database; comparing the width, depth, and arc radius of the currently collected blade foreign object damage to obtain a basic size similarity judgment result; and comparing the new damage with similar basic size with the historical damage for structural similarity to obtain a structural similarity result.
[0016] In the step (3), three indicators of target foreign object damage, namely depth, arc radius and width, are input, and these three indicators are compared with the historical damage information in the database. If the similarity meets 90%, the grayscale matrices of all historical damage images that meet the similarity conditions in the database are retrieved, and the similarity of the grayscale matrices is compared between each other. If the similarity reaches 80%, the structures are considered to be similar. If the above two similarity conditions are met, the target foreign object damage is considered to be similar to the historical damage, and several historical blade damage information with extremely high similarity is obtained. Based on the historical blade foreign object damage maintenance conditions in the database, the impact degree of the target foreign object damage is obtained.
[0017] In the step (3), the database stores three types of content: basic blade dimensions, historical damage image information, and model parameter information. The basic blade dimensions are obtained by identifying image feature information through an industrial endoscope, the historical damage image information is stored by converting the historical damage images into a grayscale matrix, and the model parameter information is obtained by retrieving maintenance model data.
[0018] Beneficial effect: The present invention covers both original standards and existing usage experience to judge FOD damage. As the usage experience becomes richer, the judgment will be more accurate. The results obtained by this method will be more conducive to making a better judgment on whether the blades that have been damaged by foreign objects are exempt from repair. BRIEF DESCRIPTION OF THE DRAWINGS
[0019] Figure 1 It is a flow chart of blade maintenance exemption judgment based on historical data;
[0020] Figure 2 This is a schematic diagram of the CFM56-7B fan blade partitions;
[0021] Figure 3 It is a schematic diagram of the decision rule based on historical data;
[0022] Figure 4 A schematic diagram of information storage in a database for historical data; DETAILED DESCRIPTION
[0023] The present invention will be further described below in conjunction with the accompanying drawings.
[0024] In this embodiment, the CFM56-7B fan blade is taken as an example.
[0025] like Figure 1 As shown, the present invention provides a method for judging whether foreign object damage is repair-free based on historical data, comprising the following steps:
[0026] (1) Inserting an industrial endoscope probe into the engine to collect blade image information, determine the location of various damages on the blade based on the blade root according to the pixel distribution, brightness, and color in the image information, and convert the damages into digital signals. Process the digital signals by computer to extract the size features of the foreign object damage, including depth, area, and angle, to form a data set;
[0027] (2) Divide the foreign object damage on the blade into different areas according to the location of the foreign object damage, such as Figure 2 As shown; then the blade foreign object damage in the data group is judged based on the available limits in the maintenance manual. The judgment criteria for blade foreign object damage are the following three basic size parameters: depth, width, and arc radius. If the size of the foreign object damage meets the maximum available limit, no repair is required; the maximum available limit of the blade is shown in Table 1:
[0028] Table 1 Usable limit types of CFM56-7B fan blades
[0029]
[0030]
[0031] (3) If the damage size does not meet the maximum available limit, a decision is made based on historical data experience, such as Figure 3 As shown, the following steps are included: coordinate classification and partitioning of blade foreign object damage information to obtain location information of foreign object damage; based on the location information, calling out damage information at the same location in the database; inputting three indicators of target foreign object damage, depth, arc radius, and width, comparing these three indicators with historical damage information in the database, and if the similarity is 90%, calling out the grayscale matrix of all historical damage images that meet the similarity conditions in the database, and comparing the similarity of the grayscale matrices between each other, and if the similarity reaches 80%, it is considered that the structure is similar, and if the above two similarity conditions are met, it is considered that the target foreign object damage is similar to the historical damage, and several historical blade damage information with extremely high similarity is obtained, and based on the historical blade foreign object damage maintenance situation in the database, the impact degree of the target foreign object damage is obtained.
[0032] like Figure 4 As shown, the database stores three types of content: basic blade dimensions, historical damage image information, and model parameter information. The basic blade dimensions are obtained by identifying image feature information through an industrial endoscope, the historical damage image information is stored by converting the historical damage images into a grayscale matrix, and the model parameter information is obtained by retrieving maintenance model data.
[0033] (4) If it is found in the empirical judgment results of historical data that the target FOD and the historical FOD meet the two similarity conditions of size and structure, and if the historical FOD has not failed in operation, it is considered that the target FOD will not fail in future operation, and the blade does not need to be repaired;
[0034] (5) If there is no clear definition in the maintenance manual and the similarity conditions are not met in the historical data comparison, the target foreign object damage is considered to be unqualified, and the failure location and judgment criteria must be given and recorded.
[0035] Through the above five steps, the repair-free judgment result of the target damaged blade can be obtained. This result adds a historical data comparison method on the basis of retaining the traditional judgment method, providing an effective solution for the damage type that is not clearly defined in the maintenance manual, thereby improving the judgment accuracy.
[0036] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.
Claims
1. A method for judging the foreign object damage without repair based on historical data, characterized in that: The following steps are involved: (1) Using an industrial endoscope to capture the location of the foreign object damage on the inspected blade based on the blade root, and identify the size and type of the foreign object damage to form a data set; (2) According to the theory of usable limit in the maintenance manual, the blade foreign object damage in the data set obtained in step (1) is judged. If the size of the foreign object damage meets the maximum usable limit, no maintenance is required; (3) If the size of the damage does not meet the maximum available limit, a judgment is made based on the experience of historical data. The steps of making a judgment based on the experience of historical data are: coordinate classification and partitioning of the blade foreign object damage information to obtain the location information of the foreign object damage; Based on the position information, call out the damage information of the same position in the database; compare the width, depth and arc radius of the currently collected blade foreign object damage to obtain the basic size similarity judgment result; Compare the new damage with the historical damage with similar basic size for structural similarity and obtain the structural similarity result; Input the three indicators of target foreign object damage, depth, arc radius, and width, and compare these three indicators with the historical damage information in the database. If the similarity meets 90%, call out the grayscale matrix of all historical damage pictures that meet the similarity conditions in the database, and compare the similarity of the grayscale matrices between each other. If the similarity reaches 80%, it is considered to be structurally similar. If the above two similarity conditions are met, the target foreign object damage is considered to be similar to the historical damage, and several historical blade damage information with extremely high similarity is obtained. Based on the historical blade foreign object damage maintenance situation in the database, the impact degree of the target foreign object damage is obtained; the database stores three types of content: basic blade size, historical damage picture information, and model parameter information. The basic blade size is obtained by identifying image feature information through an industrial endoscope, the historical damage picture information is converted into a grayscale matrix for storage, and the model parameter information is obtained by retrieving the maintenance model data; (4) If it is found in the empirical judgment results of historical data that the target FOD and the historical FOD meet the two similarity conditions of size and structure, and if the historical FOD has not failed in operation, it is considered that the target FOD will not fail in future operation, and the blade does not need to be repaired; (5) If there is no clear definition in the maintenance manual and the similarity conditions are not met in the historical data comparison, the target foreign object damage is considered to be unqualified. In this case, the failure location and judgment criteria must be given and recorded.
2. The method for determining the foreign object damage without repair based on historical data according to claim 1, characterized in that: In the step (1), the industrial endoscope probe is inserted into the engine to collect blade image information, and the position of each damage on the blade based on the blade root is determined based on the pixel distribution, brightness and color in the image information, and the position is converted into a digital signal. The digital signal is processed by a computer to extract the size characteristics of the foreign object damage, and the size characteristics include depth, area and angle.
3. The method for determining the foreign object damage without repair based on historical data according to claim 1, characterized in that: In the step (2), the foreign object damage on the blade is divided into zones according to the location where the foreign object damage occurs, and then the foreign object damage on the blade in the data group is judged based on the available limits in the maintenance manual. The judgment criteria for the foreign object damage on the blade are the following three basic dimensional parameters: depth, width, and arc radius.