A precise manufacturing method for a large double-sided structural member web

Abstract

A large-scale double-sided structure web precision manufacturing method belongs to the technical field of numerical control machining of aircraft structures. The large-scale double-sided structure web precision manufacturing method is based on a digital machining platform integrated with an on-machine wall thickness measuring device, an industrial computer and a numerical control machining machine tool. Through process planning and programming before machining, the web is machined and the wall thickness is measured on the numerical control machine tool during the machining process driven by the program, and the measurement results are analyzed and processed. Finally, the compensation machining program is intelligently generated to complete the numerical control machining of the web structure, and the large-scale double-sided structure web precision manufacturing is realized. The present application can realize the precise machining of the web structure of large-scale structures, effectively reduce the experience dependence of the operator in web machining, reduce the workload of the operator, ensure the quality stability of the web structure machining, effectively improve the machining efficiency, and has important significance for realizing the intelligent manufacturing of the structure.

Description

Technical Field

[0001] This invention relates to a method for the precise manufacturing of the web of a large double-sided structural component, belonging to the field of CNC machining technology for aircraft structural components. Background Technology

[0002] Aircraft structural component design is increasingly trending towards larger, more complex, and lighter designs, placing higher demands on structural component manufacturing technology. Web features are among the most typical characteristics of large structural components, with hundreds of webs found in a single large component. Typically, web features primarily serve to ensure structural strength, and their positional tolerances are not critical; however, their thickness tolerance is a key control factor in their manufacturing. Exceeding the lower tolerance of the web thickness can affect structural strength; exceeding the upper tolerance will lead to excessive weight, which is also unacceptable in structural component development. Furthermore, as aircraft performance requirements continue to increase, weight control becomes increasingly stringent, which is also reflected in the control of web thickness tolerances for large structural components.

[0003] Currently, in the machining of web plates for large double-sided structural components, the combined effects of various factors such as the rigidity of the part itself, clamping and positioning deviations, stress, and machine tool accuracy make it difficult to guarantee that the web plate thickness meets design requirements when CNC programming is done solely based on theoretical models. Furthermore, the deviation varies from machining session to session, making it impossible to accurately predict deviations during the CNC programming stage. Currently, on production lines, the main method involves manually stopping the machine to inspect the web plate thickness, then manually estimating the compensation amount based on the deviation and manually modifying the CNC machining program. This solution suffers from low implementation efficiency, high reliance on operator experience, and poor consistency in machining quality. Therefore, this paper proposes an intelligent precision manufacturing method for web plates to solve the precision manufacturing challenges and meet the rapidly developing needs of the current aerospace manufacturing industry. Summary of the Invention

[0004] This invention proposes a method for the precise manufacturing of the web of a large double-sided structural component. Based on a digital machining platform integrating an on-board wall thickness measuring device, an industrial computer, and a CNC machine tool, the method involves pre-machining process planning and programming, followed by program-driven web machining and wall thickness measurement on a CNC machine tool. The measurement results are then analyzed and processed to intelligently generate a compensation machining program, thereby completing the CNC machining of the web structure and achieving the precise manufacturing of the web of a large double-sided structural component.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0006] A method for precision manufacturing of the web of a large double-sided structural component includes the following steps:

[0007] (1) Analyze the structural characteristics of the structural components and identify the web structure that requires wall thickness measurement and compensation processing during the intermediate processing;

[0008] (2) For areas where web thickness needs to be measured in-machine during intermediate processes, plan the web thickness measurement points;

[0009] (3) Based on the structure of the CNC machine tool, post-process the measurement points planned in step (2) to generate the web wall thickness measurement program.

[0010] (4) Compile a processing program for the web structure identified in step (1) and add a labeling annotation at the beginning of the program segment;

[0011] (5) The machining program for the associated sidewalls of the web structure identified in step (1) is compiled. When the machining process adopts the process of milling the web first and then the sidewalls, it is necessary to add an identification note at the beginning of the relevant program segment; otherwise, it is not necessary to add an identification note in the program segment.

[0012] (6) Import the machining program and measurement program into the CNC machine tool control system, and carry out CNC machining of the structural parts according to the process plan. Before the machining process reaches the finishing of the second web surface, call the web thickness in-machine measurement program to measure the web wall thickness, and transmit and store the measurement results to the industrial control computer;

[0013] (7) Analyze and process the measurement results on the industrial control computer, evaluate the current processing status of the web, and calculate the corresponding compensation strategy;

[0014] (8) Based on the calculation results in step (7), the customized program adjustment software is applied on the industrial control computer to complete the intelligent adjustment of the web plate finishing program.

[0015] (9) The adjusted machining program is transmitted to the CNC machine tool control system, and the program is called to complete the finishing of the web surface, so as to realize the precise manufacturing of the web of large double-sided structural parts.

[0016] The beneficial effects of this invention are:

[0017] This invention proposes a method for the precise manufacturing of the web of large double-sided structural components, based on a digital processing platform integrating an on-board wall thickness measuring device, an industrial computer, and a CNC machine tool. Technicians only need to prepare the process in the early stages; subsequent processing requires no manual intervention to achieve precise machining of the web structure of large structural components. This effectively reduces the reliance on operator experience in web machining, decreases operator workload, ensures the quality stability of web structure machining, and effectively improves processing efficiency. Furthermore, it is of great significance for realizing the intelligent manufacturing of structural components. Attached Figure Description

[0018] Figure 1 Axonometric drawing of a double-sided structural member including a web structure;

[0019] Figure 2 (a) is a schematic diagram of the web structure and the associated sidewall structure of the web; Figure 2 (b) is a sectional view of point AA in (a);

[0020] Figure 3 A schematic diagram showing the location of three thickness measurement points on the web surface;

[0021] Figure 4 A schematic diagram showing the location of 5 thickness measurement points on the web surface;

[0022] Among them: 1, 2, 3, 4 are related sidewall structures of the web (1 is related sidewall structure of the lower web, 2 is related sidewall structure of the right lower web, 3 is related sidewall structure of the upper web, 4 is related sidewall structure of the left web), 5 is the web structure. Detailed Implementation

[0023] The present invention will be further described below with reference to specific implementation examples.

[0024] This invention proposes a method for the precise manufacturing of the web of large double-sided structural components. On a CNC machine tool with an integrated wall thickness measuring device, automated and intelligent machining of the web of double-sided structural components is achieved, solving the problem of ensuring web thickness in the machining of aircraft double-sided structural components. The following detailed description of embodiments of this invention, in conjunction with the accompanying drawings, illustrates these embodiments. These embodiments are implemented based on the inventive technical solution, providing detailed implementation methods and specific processes. However, the scope of protection of this invention is not limited to the following embodiments.

[0025] The detailed steps of implementing this invention are as follows:

[0026] (1) Analyze the structural features of the part and identify the weakly rigid webs in the structural components. Weakly rigid webs typically have characteristics such as a web wall thickness of no more than 3mm, lack of support at local edges, and excessively large web width. After identification, these web structural features are sorted and numbered. The web structures are arranged sequentially in a certain direction as much as possible. This effectively reduces the idle travel during machine measurement of web thickness, saves actual time spent measuring web wall thickness on the machine, and ensures measurement efficiency. Finally, this yields the set of web structures for which web wall thickness measurement is required before the second-side finishing of the web. In the formula, i represents the web plate number, and m represents the total number of web plate surfaces.

[0027] (2) Plan the web thickness measurement points for each web surface in the web structure set F. Generally, when both the long and short sides of the web are no more than 250 mm, take 3 thickness measurement points on the web surface; when the long side of the web is longer than 250 mm, take 5 thickness measurement points on the web surface. The principle for selecting thickness measurement points is: take the center point of the surface as the center, and disperse the points outwards to ensure that the discrete point data can accurately represent the actual thickness of the entire web surface. See the attached figure for the schematic diagram of taking 3 and 5 thickness measurement points on the web surface.

[0028] (3) In the part model, after completing the planning and selection of web thickness measurement points, the coordinate values ​​and external normal vectors of each point are obtained sequentially. The point information of the thickness measurement point at the j-th point on the i-th web of the part is represented as p. ij = (X, Y, Z, I, J, K). Then, combined with the specific structure of the in-machine thickness measurement machine, the measurement points are post-processed to generate a specific machine tool measurement program, which is used to control the CNC machine tool to perform in-machine measurement of the web wall thickness. Taking a BC-axis milling and turning composite machine as an example, the point post-processing method is as follows:

[0029] Assume p ij Let n be a measurement point on a certain web. ij Let N be the unit normal vector corresponding to this point. For ease of calculation, all measurement points are represented as matrix P, and the unit normal vectors corresponding to all points are represented as N.

[0030] The rotation axis C-axis can be represented as:

[0031] If n ijy =0, then C=0

[0032] If n ijx =0,n ijy If >0, then C = 90°

[0033] If n ijx =0,n ijy If <0, then C = -90°

[0034] If n ijx >0, then

[0035] If n ijx <0,n ijy >0, then

[0036] If n ijx <0,n ijy <0, then

[0037] The corresponding rotation matrix is ​​expressed as:

[0038]

[0039] The actual tool position point P' and the actual normal vector N' are calculated as follows:

[0040] P′=P*R

[0041] N′=N*R

[0042] Finally, based on the actual tool position point, the B swing angle value is obtained:

[0043] If n′ ijx =0,n′ ijz If >0, then B = 90°

[0044] If n′ ijx =0,n′ ijz If <0, then B = -90°

[0045] If n′ ijx ≠0, then

[0046] (4) Web plate machining program compilation: For the web plate structure identified in step (1), CAM software is used to compile the web plate machining program. Then, at the beginning of the web plate machining program segment, a special mark is made in the form of a comment, with the mark form being “;i”, where i represents the current web plate surface number.

[0047] (5) Machining program for sidewalls associated with the web: For the sidewalls associated with the web structure identified in step (1), machining programs are compiled using CAM software. When the machining process adopts the method of milling the web first and then the sidewalls, a special annotation is required at the beginning of the relevant program segment, in the form of ";ij", where i represents the web surface number and j represents the number of the sidewall surface associated with the web surface; when the machining process adopts the method of milling the sidewalls first and then the web, no special annotation is required for the relevant program segment.

[0048] (6) Import the machining program and measurement program into the CNC machine tool control system, and carry out CNC machining of the structural parts according to the process plan. Before the machining process reaches the finishing of the second web surface, call the web thickness in-machine measurement program to measure the web wall thickness, and transmit and store the measurement results to the industrial control computer.

[0049] (7) Custom-developed analysis software is used on an industrial control computer to analyze and process the measurement results, evaluate the final pre-machining state of each web in the web structure set F, and calculate a compensation strategy based on the evaluation state. The software implementation principle and core algorithm are as follows: The wall thickness measurement results of each web surface in the web structure set are analyzed and calculated one by one to evaluate the current machining wall thickness state of the web surface, and a corresponding compensation strategy is planned based on the evaluation results. Taking web f as an example... iFor example, the specific implementation method is explained as follows:

[0050] Assuming a web structure assembly Middle web f i There are 3 wall thickness measurement points p i1 p i2 p i3 The corresponding measured wall thickness is δ i1 δ i2 δ i3 δ min and δ max T represents the minimum and maximum measured wall thickness of the web surface, respectively. min and T max These represent the minimum and maximum allowable web wall thicknesses, respectively; T represents the expected target web thickness, which lies between the maximum and minimum allowable thicknesses; r represents the allowance before finishing the web; and k represents the allowance before finishing. i Indicates the processing of web plate f i The corresponding tool length compensation value, where H represents the actual tool length during machining.

[0051] (a) When δ min -T min When the value is less than 0, it indicates that the wall thickness of the web plate has exceeded the allowable minimum value before finishing, and the part is out of tolerance and cannot be remedied.

[0052] (b) When δ min -T min >0 and δ min -rT min ≤0 and δ max -rT min When the value is ≤0, it indicates that all points on the web are too thin. The wall thickness can be ensured by adding tool length compensation during machining. The tool compensation amount is k. i =H+T min -(δ min -r);

[0053] (c) When δ max -rT max ≥0 and δ min -rT max When ≥0, it indicates that all points on the web are too thick. Compensation is achieved by increasing tool compensation during machining. max -δ min ≤T max -T min At that time, the tool compensation amount is k i =H+T-(δ) max -r); when δ max -δ min >T max -T min At that time, the tool compensation amount is ki =H+T min -(δ min -r);

[0054] (d) When T min ≤δ min -r≤T max And T min ≤δ max -r≤T max At that time, the thickness at the measurement points on the web surface is within the tolerance range, and no compensation processing is required;

[0055] (e) When δ min -T min >0 and δ min -rT min ≤0 and δ max -rT min When the value is ≥0, it indicates that some points on the web are too thin, while others are normal or too thick, and the tool compensation amount is k. i =H+T min -(δ min -r);

[0056] At this point, the web plate f is complete. i Assess the current wall thickness condition and, based on the assessment results, plan corresponding compensation strategies.

[0057] (8) On the industrial control computer, a custom-developed program adjustment software is used to complete the intelligent adjustment of the web plate finishing program. The implementation principle and core algorithm of the software are as follows: According to the web plate order in the web plate structure set F, the web plate machining program and the web plate associated sidewall machining program are adjusted one by one. First, based on the evaluation results in step (7), if the current web plate machining needs to be compensated, the current web plate finishing program and the web plate associated sidewall finishing program are adjusted for program compensation; if no compensation is needed, the current web plate machining program and the web plate associated sidewall machining program are not modified.

[0058] (9) Save the machining program adjusted in the previous step and import it into the CNC machining system. Call the program to complete the finishing of the web surface and realize the precise manufacturing of the web of large double-sided structural parts.

[0059] The above-described embodiments are merely illustrative of the implementation methods of the present invention, but should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the protection scope of the present invention.

Claims

1. A method for precision manufacturing of the web of a large double-sided structural component, characterized in that, The method for precise manufacturing of the web of large double-sided structural components is based on a digital machining platform integrating an on-board wall thickness measuring device, an industrial computer, and a CNC machine tool. Through pre-machining process planning and programming, the method is program-driven during machining, performing web machining and wall thickness measurement on the CNC machine tool. The measurement results are analyzed and processed, and finally, an intelligent compensation machining program is generated to complete the CNC machining of the web structure, achieving precise manufacturing of the web of large double-sided structural components. The method includes the following steps: (1) Analyze the structural characteristics of the structural components and identify the web structure that requires wall thickness measurement and compensation processing during the intermediate processing; (2) For areas where web thickness needs to be measured in-machine during intermediate processes, plan the web thickness measurement points; (3) Based on the structure of the CNC machine tool, post-process the measurement points planned in step (2) to generate the web wall thickness measurement program. In the part model, after completing the planning and selection of web thickness measurement points, the coordinate values ​​and external normal vectors of each point are obtained sequentially. The point information of the j-th thickness measurement point on the i-th web of the part is represented as follows: Then, based on the specific structure of the in-machine thickness measurement machine tool, the measurement points are post-processed to generate a measurement method specific to the machine tool, used to control the CNC machine tool to perform in-machine measurement of the web wall thickness; the CNC machine tool is a BC-axis milling and turning composite machine tool, and the point post-processing method is as follows: Assumption For a measurement point on a certain web, Let N be the unit normal vector corresponding to this point. For ease of calculation, all measurement points are represented as matrix P, and the unit normal vectors corresponding to all points are represented as N. The rotation axis C-axis can be represented as: The corresponding rotation matrix is ​​expressed as: The actual tool position point P ’ The actual normal vector N ’ Calculated as Finally, based on the actual tool position point, the B swing angle value is obtained: ； (4) Compile a processing program for the web structure identified in step (1) and add a labeling annotation at the beginning of the program segment; (5) Compile a machining program for the associated sidewalls of the web structure identified in step (1). When the machining process adopts the method of milling the web first and then the sidewalls, it is necessary to add an identification note at the beginning of the relevant program segment; otherwise, it is not necessary to add an identification note in the program segment. (6) Import the machining program and measurement program into the CNC machine tool control system, and carry out CNC machining of the structural parts according to the process plan; before the machining process reaches the finishing of the second web surface, call the web thickness in-machine measurement program to measure the web wall thickness, and transmit and store the measurement results to the industrial control computer. (7) Analyze and process the measurement results on the industrial control computer, evaluate the current processing status of the web, and calculate the corresponding compensation strategy; (8) Based on the calculation results in step (7), the customized program adjustment software is applied on the industrial control computer to complete the intelligent adjustment of the web finishing program; (9) The adjusted machining program is transmitted to the CNC machine tool control system, and the program is called to complete the finishing of the web surface, so as to realize the precise manufacturing of the web of large double-sided structural parts.

2. The method for precise manufacturing of the web of a large double-sided structural component according to claim 1, characterized in that, Specifically, (1) refers to: Analyze the structural features of the part and identify the weakly rigid webs in the structural components; after identification, sort and number these web structural features; obtain the set of web structures for which web wall thickness measurement is required before the second-side finishing of the web. In the formula, i represents the web plate number, and m represents the total number of web plate surfaces.

3. The method for precise manufacturing of the web of a large double-sided structural component according to claim 2, characterized in that, Specifically, (2) refers to: Web structure assembly Plan the web thickness measurement points one by one on the web surface; when the long side and short side of the web are both no more than 250mm, take 3 thickness measurement points on the web surface; when the long side of the web is greater than 250mm, take 5 thickness measurement points on the web surface; the principle for selecting thickness measurement points is: take the center point of the surface as the center and disperse the points from the center to the surrounding area.

4. The method for precision manufacturing of the web of a large double-sided structural component according to claim 1, characterized in that, Specifically, (4) refers to: Web plate machining: For the web plate structure identified in step (1), CAM software is used to compile the web plate machining program. Then, at the beginning of the web plate machining program segment, a special annotation is made in the form of ";i", where i represents the current web plate surface number.

5. The method for precision manufacturing of the web of a large double-sided structural component according to claim 4, characterized in that, Specifically, (5) refers to: Machining of the sidewalls associated with the web: For the sidewalls associated with the web structure identified in step (1), CAM software is used to compile the machining program; when the machining process adopts the process of milling the web first and then the sidewalls, it is necessary to make special markings in the form of comments at the beginning of the relevant program segments, and the marking form is ";ij", where i represents the web surface number and j represents the number of the sidewall surface associated with the web surface; when the machining process adopts the process of milling the sidewalls first and then the web, it is not necessary to make special markings on the relevant program segments.

6. The method for precision manufacturing of the web of a large double-sided structural component according to claim 5, characterized in that, Specifically, (6) refers to: The machining methods for the web plate and the associated sidewalls are imported into the CNC machine tool control system, and the structural parts are manufactured by CNC machining according to the process plan. Before the machining process reaches the finishing of the second web plate surface, the web plate thickness measurement program is called to measure the web plate wall thickness, and the measurement results are transmitted and stored to the industrial control computer.

7. The method for precision manufacturing of the web of a large double-sided structural component according to claim 6, characterized in that, Specifically, (7) refers to: The measurement results are analyzed and processed on an industrial computer to evaluate the web structure assembly. The final pre-machining state of each web plate is determined, and a compensation strategy is calculated based on the evaluation state. The wall thickness measurement results of each web plate surface in the web plate structure set are analyzed and calculated to evaluate the current machining wall thickness state of the web plate surface. Based on the evaluation results, a corresponding compensation strategy is planned. The web plate... Explanation: Assuming a web structure assembly middle web There are 3 wall thickness measurement points. , , The corresponding measured wall thickness is , , , and These represent the minimum and maximum measured wall thicknesses on the web surface, respectively. and These represent the minimum and maximum allowable design values ​​for the web wall thickness, respectively. This represents the expected target web thickness, which lies between the maximum and minimum allowable values. This indicates the allowance before the web is finished. Indicates the processing of web plate The corresponding tool length compensation value, Indicates the actual tool length used in machining; (a) when This indicates that the web thickness has exceeded the allowable minimum before finishing, and the part's deviation is irreparable. (b) When and and When the thickness is too thin at all points on the web, it indicates that the wall thickness can be maintained by adding tool length compensation. The tool compensation amount is... ; (c) When and When this indicates that all points on the web are too thick, compensation is achieved by increasing tool compensation during machining. At that time, the tool compensation amount is ;when At that time, the tool compensation amount is ; (d) When and At that time, the thickness at the measurement points on the web surface is within the tolerance range, and no compensation processing is required; (e) when and and When this occurs, it indicates that some points on the web are too thin, while others are normal or too thick, and the tool compensation amount is... ; At this point, the web is complete. Assess the current wall thickness condition and, based on the assessment results, plan corresponding compensation strategies.

8. A method for precise manufacturing of the web of a large double-sided structural component according to claim 7, characterized in that, Specifically, (8) refers to: Intelligent adjustment of the web finishing program is completed on the industrial computer: according to the web structure assembly. In the order of the web plates, the web plate machining program and the web plate associated sidewall machining program are adjusted one by one; first, based on the evaluation results in step (7), if the current web plate machining needs to be compensated, the current web plate finishing program and the web plate associated sidewall finishing program are adjusted to compensate; if no compensation is needed, the current web plate machining program and the web plate associated sidewall machining program are not modified.

9. A method for precise manufacturing of the web of a large double-sided structural component according to claim 8, characterized in that, Specifically, (9) refers to: Save the adjusted machining program from the previous step and import it into the CNC machining system. Call the program to complete the finishing of the web surface, thereby achieving the precise manufacturing of the web of a large double-sided structural component.

Images