Precise manufacturing method for web of large double-sided structural member

Abstract

The invention discloses an accurate manufacturing method for a large double-sided structural member web, and belongs to the technical field of aircraft structural member numerical control machining. The precise manufacturing method for the web of the large double-sided structural member is based on a digital processing platform integrated with an on-machine wall thickness measuring device, an industrial personal computer and a numerical control processing machine tool, through process planning and programming before processing, web processing and wall thickness measurement are carried out on the numerical control processing machine tool under the driving of a program in the processing process, and a measurement result is analyzed and processed, so that the precise manufacturing of the web of the large double-sided structural member is realized. And finally, a compensation machining program is intelligently generated, numerical control machining of the web structure is completed, and precise manufacturing of the large double-face structural part web is achieved. Precise machining of the web structure of the large structural part can be achieved, the dependence of web machining on experience of operators is effectively reduced, the workload of the operators is reduced, the quality stability of web structure machining is guaranteed, the machining efficiency is effectively improved, and meanwhile the method has important significance on intelligent manufacturing of the structural part.

Description

Technical Field

[0001] The present invention relates to a method for precisely manufacturing the web of a large double-sided structural member, belonging to the technical field of numerical control machining of aircraft structural members. Background Technique

[0002] The design of aircraft structural members is gradually developing towards the direction of being large-sized, complex, and lightweight, posing higher requirements for structural member manufacturing technologies. The web feature is one of the most typical features in large structural members, and the number of webs in a large structural member reaches hundreds. Usually, the web feature mainly plays a role in ensuring the structural strength in the structural member, and its position tolerance requirements are not high, but its thickness tolerance is the key control factor in its machining and manufacturing. If the web thickness tolerance is below the lower limit, it may affect the structural strength; if the web thickness tolerance exceeds the upper limit, it will cause the weight of the structural member to be overweight, which is also unacceptable in the development of structural members. Moreover, with the continuous improvement of the requirements for aircraft performance, weight control has become increasingly strict, which is also reflected in the control of the web thickness tolerance of large structural members.

[0003] Currently, during the machining process of the web of a large double-sided structural member, due to the comprehensive influence of various factors such as the rigidity of the part itself, clamping and positioning deviation, stress, and machine tool accuracy, it is difficult to ensure that the web thickness meets the design requirements by completely programming according to the theoretical model. Moreover, in each machining process, the deviation situations are different. Therefore, this problem cannot accurately estimate the deviation situation during the numerical control programming stage. Currently, in the production line, it is mainly necessary to manually stop the machine to detect the web thickness, and then, based on the deviation situation, manually estimate the compensation amount and manually modify the numerical control machining program. This solution has problems such as low implementation efficiency, high dependence on the experience of operators, and poor consistency of machining quality. For this reason, an intelligent method for precisely manufacturing the web is proposed to solve the problem of precisely manufacturing the web and meet the rapid development needs of the current aviation manufacturing industry. Summary of the Invention

[0004] The present invention proposes a method for precisely manufacturing the web of a large double-sided structural member. Based on a digital machining platform integrated with an in-machine wall thickness measuring device, an industrial control computer, and a numerical control machining tool, through process planning and programming before machining, driven by a program during the machining process, the web machining and wall thickness measurement are carried out on the numerical control machine tool, and the measurement results are analyzed and processed. Finally, a compensation machining program is intelligently generated to complete the numerical control machining of the web structure and realize the precise manufacturing of the web of the large double-sided structural member.

[0005] In order to achieve the above object, the technical solution adopted by the present invention is as follows:

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

[0007] (1) Analyze the structural characteristics of the structural components, and identify the web structures that require wall thickness measurement and compensation machining during the intermediate machining process;

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

[0009] (3) Combine the structural form of the numerical control machine tool, post - process the measurement points planned in step (2) to generate an on - machine measurement program for the web wall thickness;

[0010] (4) Compile the machining program for the web structure identified in step (1), and add a marking comment at the beginning of the program segment;

[0011] (5) Compile the machining program for the associated side wall surfaces of the web structure identified in step (1). When the machining process uses the process plan of milling the web first and then the side wall, a marking comment needs to be added at the beginning of the relevant program segment; otherwise, there is no need to add a marking comment in the program segment;

[0012] (6) Import the machining program and the measurement program into the numerical control machine tool control system, and carry out numerical control machining and manufacturing of the structural components according to the process plan. Before the second - side web surface of the structural component is machined to the finish - machining stage, call the on - machine measurement program for the web thickness 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 machining state of the web, and calculate the corresponding compensation strategy;

[0014] (8) According to the calculation results in step (7), on the industrial control computer, use the custom - developed program adjustment software to complete the intelligent adjustment of the web finish - machining program.

[0015] (9) Transmit the adjusted machining program to the numerical control machine tool control system, call this program to complete the finish - machining of the web surface, and achieve precise manufacturing of the web of large - scale double - sided structural components.

[0016] Advantages of the present invention:

[0017] Based on the digital machining platform integrating the on - machine wall thickness measuring device, industrial control computer, and numerical control machine tool, the present invention proposes a method for precise manufacturing of the web of large - scale double - sided structural components. Technicians only need to do a good job in the early - stage process preparation. During the subsequent machining, without manual intervention, precise machining of the web structure of large - scale structural components can be achieved, effectively reducing the dependence on the experience of operators, reducing the workload of operators, ensuring the quality stability of the web structure machining, effectively improving the machining efficiency. At the same time, it is of great significance for realizing the intelligent manufacturing of structural components. Description of the drawings

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

[0019] Figure 2 (a) Schematic diagram of the web structure and the side wall structure associated with the web; Figure 2 (b) Cross-sectional view taken at A-A in (a);

[0020] Figure 3 Schematic diagram of taking 3 thickness measurement points on the web surface;

[0021] Figure 4 Schematic diagram of taking 5 thickness measurement points on the web surface;

[0022] Wherein: 1, 2, 3, 4 are the side wall structures associated with the web (1 is the lower side wall structure associated with the web, 2 is the lower right side wall structure associated with the web, 3 is the upper side wall structure associated with the web, 4 is the left side wall structure associated with the web), and 5 is the web structure. Specific implementation method

[0023] The present invention will be further described below in conjunction with specific implementation cases.

[0024] The present invention proposes a method for precise manufacturing of the web of a large double-sided structural member. On a numerically controlled machine tool integrated with an in-machine wall thickness measuring device, automatic and intelligent processing of the web of the double-sided structural member is realized, and the problem of ensuring the web thickness in the processing of the aircraft double-sided structural member is solved. The implementation cases of the present invention will be described in detail below with reference to the accompanying drawings. This implementation case is implemented on the premise of the technical solution of the invention, and the detailed implementation method and specific implementation process are given. However, the protection scope of the present invention is not limited to the following implementation cases.

[0025] The detailed steps of the implementation of the present invention are as follows:

[0026] (1) Analyze the structural characteristics of the part, identify the weakly rigid webs in the structural member. Usually, the weakly rigid webs have characteristics such as the web wall thickness not greater than 3 mm, no support at the local edge of the web, and the web plate width is too large, etc. After identification, these web structural characteristics are sorted and numbered. The web structure sorting should be arranged in a certain direction as much as possible, which can effectively reduce the idle stroke in the in-machine measurement of the web thickness, save the time for actually measuring the web wall thickness in the machine, and ensure the measurement efficiency. Finally, a set of web structures that need to measure the web wall thickness before the second-side finish machining of the part is obtained. In the formula, i represents the web number, and m represents the total number of web surfaces.

[0027] (2) Plan the wall thickness measurement points for each web surface in the web structure set F. Generally, when both the long side and the short side of the web are no more than 250 mm, take 3 thickness measurement points on the web surface; when the length of the long side of the web is greater than 250 mm, take 5 thickness measurement points on the web surface. The principle for taking thickness measurement points: Take points centered on the center point of the surface and disperse from the center to the surrounding to ensure that the discretely taken data can accurately represent the actual wall thickness data of the entire web surface. The schematic diagrams for taking 3 thickness measurement points and 5 thickness measurement points on the web surface are shown in the attached drawings.

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

[0029] Assume that p ij is a measurement point on a certain web, and n ij is the unit normal vector corresponding to this point. For the convenience of calculation, represent all measurement points as matrix P and represent the unit normal vectors corresponding to all points as N.

[0030] For the rotary axis C axis, it can be expressed as:

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

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

[0033] If n ijx = 0, n ijy < 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] Then the actual tool point P' and the actual normal vector N' are calculated as

[0040] P′ = P * R

[0041] N′ = N * R

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

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

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

[0045] If n′ ijx ≠ 0, then

[0046] (4) Programming of the web machining program: For the web structure identified in step (1), use CAM software to program the web machining program. Then, at the beginning of the web machining program segment, make a special identification in the form of a comment, and the identification form is ";i", where i represents the current web surface number.

[0047] (5) Programming of the side wall machining program associated with the web: For the associated side walls of the web structure identified in step (1), use CAM software to program the machining program. When the machining process uses the process plan of milling the web first and then the side walls, it is necessary to make a special identification in the form of a comment at the beginning of the relevant program segment, and the identification form is ";i.j", where i represents the web surface number and j represents the number of the side wall surface associated with the web surface; when the machining process uses the process plan of milling the side walls first and then the web, it is not necessary to make a special identification for the relevant program segment.

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

[0049] (7) Use the custom-developed analysis software on the industrial control computer to analyze and process the measurement results, evaluate the state of each web before the final finish machining in the web structure set F, and calculate the compensation strategy based on the evaluation state. The implementation principle and core algorithm of this software are as follows: Analyze and calculate the wall thickness measurement results of each web surface in the web structure set one by one, evaluate the current machining wall thickness state of the web surface, and plan the corresponding compensation strategy based on the evaluation results. Take web f iTake the following as an example to illustrate the specific implementation method:

[0050] Suppose the web structure set The web f i has 3 wall thickness measurement points p i1 、p i2 、p i3 , and the corresponding measured wall thickness values are δ i1 、δ i2 、δ i3 , δ min and δ max respectively represent the minimum and maximum measured wall thickness values of the web surface. T min and T max respectively represent the allowable minimum and maximum design wall thickness values of the web. T represents the expected target thickness of the web, which is between the allowable maximum and minimum values. r represents the allowance before finish machining of the web. k i represents the tool length compensation value corresponding to machining the web f i , and H represents the actual tool length of the machining tool.

[0051] (a) When δ min -T min < 0, it indicates that the wall thickness of the web has exceeded the allowable minimum value before finish machining, and the part is out of tolerance and cannot be remedied;

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

[0053] (c) When δ max -r-T max ≥ 0 and δ min -r-T max ≥ 0, it indicates that all points of the web are too thick, and compensation machining is carried out by increasing the tool offset. When δ max -δ min ≤ T max -T min , the tool compensation amount is k i = H + T-(δ max -r); When δ max -δ min > T max -T min > 0, 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 this time, the thickness at the measuring points on the surface of the web plate is within the tolerance range, and no compensation machining is required;

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

[0056] So far, the evaluation of the current machining wall thickness state of the web f i is completed, and according to the evaluation results, the corresponding compensation strategy is planned.

[0057] (8) On the industrial control computer, use the custom-developed program adjustment software to complete the intelligent adjustment of the web finishing program. The implementation principle and core algorithm of this software are as follows: According to the web order in the web structure set F, adjust the web machining program and the web-related side wall machining program one by one. First, according to the evaluation results in step (7), if the current web machining requires machining compensation, then perform program compensation adjustment on the current web finishing program and the web-related side wall finishing program; if no compensation needs to be added, do not modify the current web machining program and the web-related side wall machining program.

[0058] (9) Save the machining program adjusted in the previous step and import it into the numerical control machining system, and call this program to complete the finishing of the web surface, realizing the precise manufacturing of the web of large double-sided structural parts.

[0059] The above embodiments only represent the implementation modes of the present invention, but should not be construed as limiting the scope of the patent of the present invention. It should be noted that for those skilled in the art, without departing from the concept of the present invention, several deformations and improvements can still be made, and these all belong to the protection scope of the present invention.

Claims

1. A precise manufacturing method for the web of a large-scale double-sided structural member, characterized in that The precise manufacturing method for the web of large-scale double-sided structural parts is based on a digital processing platform integrated with an in-machine wall thickness measuring device, an industrial control computer, and a numerically controlled machining tool. Through pre-processing process planning and programming, during the machining process, it is driven by a program, and the web machining and wall thickness measurement are carried out on the numerically controlled machine tool, and the measurement results are analyzed and processed. Finally, a compensation machining program is intelligently generated to complete the numerical control machining of the web structure and achieve the precise manufacturing of the web of large-scale double-sided structural parts, including the following steps: (1) Analyze the structural characteristics of the structural part to identify the web structure that requires wall thickness measurement and compensation machining during the machining intermediate process; (2) For the area where the web thickness needs to be measured in the machine during the intermediate process, plan the wall thickness measurement points on the web; (3) Combine the structural form of the numerically controlled machine tool to post-process the measurement points planned in step (2) to generate an in-machine wall thickness measurement program for the web; (4) Compile a machining program for the web structure identified in step (1), and add a marking comment at the beginning of the program segment; (5) Compile a machining program for the associated side wall surface of the web structure identified in step (1). When the machining process uses a process plan of milling the web first and then the side wall, a marking comment needs to be added at the beginning of the relevant program segment; otherwise, there is no need to add a marking comment in the program segment; (6) Import the machining program and the measurement program into the numerically controlled machine tool control system, and carry out the numerical control machining and manufacturing of the structural part according to the process plan; when the machining process reaches before the finish machining of the second side web surface, call the in-machine wall thickness measurement program for the web to measure the wall thickness of the web, and the measurement results are transmitted and stored in the industrial control computer; (7) Analyze and process the measurement results on the industrial control computer, evaluate the current machining state of the web, and calculate the corresponding compensation strategy; (8) According to the calculation results in step (7), on the industrial control computer, use the custom-developed program adjustment software to complete the intelligent adjustment of the web finish machining program; (9) Transmit the adjusted machining program to the numerically controlled machine tool control system, and call this program to complete the finish machining of the web surface, realizing the precise manufacturing of the web of large-scale double-sided structural parts.

2. The precise manufacturing method of the web of a large double-sided structural member according to claim 1, characterized in that, The specific content of (1) is as follows: Analyze the structural characteristics of the part, identify the weak-rigidity webs in the structural members; after identification, sort and number these web structural characteristics; obtain the set of web structures that need to be measured for web wall thickness before the second-side finish machining of the webs of this part In the formula, i represents the web number, and m represents the total number of web surfaces.

3. A precise manufacturing method for the web of a large double-sided structural member according to claim 2, characterized in that, The specific content of (2) is as follows: Plan the wall thickness measurement points on each web surface in the web structure set F one by one; when both the long side and the short side of the web are not greater than 250 mm, take 3 thickness measurement points on the web surface; when the length of the long side of the web is greater than 250 mm, take 5 thickness measurement points on the web surface; the principle for taking the thickness measurement points: taking the center point of the surface as the center, and dispersing the points from the center to the surrounding.

4. A precise manufacturing method for the web of a large double-sided structural member according to claim 2, characterized in that The specific content of (3) is as follows: In the part model, after completing the planning and selection of the web thickness measurement points, the coordinate values and the external normal vectors at each point are obtained in sequence. The point information of the j-th thickness measurement point on the i-th web in the part is expressed as p ij =(X, Y, Z, I, J, K); then, combined with the specific in-machine thickness measurement machine tool structure form, the measurement points are post-processed to generate a measurement method for a specific machine tool, which is used to control the numerical control machine tool to perform in-machine measurement of the web wall thickness. Taking a turning-milling compound machine tool with a BC axis as an example, the point post-processing method is as follows: Assume p ij is a measurement point on a certain web, and n ij is the unit normal vector corresponding to this point. For the convenience of calculation, all measurement points are represented as matrix P, and the unit normal vectors corresponding to all points are represented as N; For the rotary axis C axis, it can be expressed as: If n ijy = 0, then C = 0 If n ijx = 0, n ijy > 0, then C = 90° If n ijx = 0, n ijy < 0, then C = -90° If n ijx > 0, then If n ijx <0, n ijy > 0, then If n ijx <0, n ijy <0, then The corresponding rotation matrix is expressed as: Then the actual tool point P' and the actual normal vector N' are calculated as P′ = P * R N′ = N * R Finally, according to the actual tool point, the B swing angle value is obtained: If n′ ijx = 0, n′ ijz > 0, then B = 90° If n′ ijx = 0, n′ ijz < 0, then B = -90° If n' ijx ≠ 0, then 5. A precise manufacturing method for the web of a large double-sided structural member according to claim 4, characterized in that The specific content of (4) is as follows: Web machining: For the web structure identified in step (1), use CAM software to compile a web machining program, and then, at the beginning of the web machining program segment, make a special mark in the form of a comment, and the marking form is ";i", where i represents the current web surface number.

6. A precise manufacturing method for the web of a large double-sided structural member according to claim 5, characterized in that The specific content of (5) is as follows: Web-associated sidewall machining: For the associated sidewalls of the web structure identified in step (1), use CAM software to prepare the machining program; when the machining process uses the process plan of milling the web first and then the sidewalls, special identification needs to be made in the form of comments at the beginning of the relevant program segments, and the identification form is "; i.j", 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 uses the process plan of milling the sidewalls first and then the web, no special identification is required for the relevant program segments.

7. A precise manufacturing method for the web of a large double-sided structural member according to claim 6, characterized in that The specific content of (6) is as follows: Import the web machining and the machining methods of the sidewalls associated with the web into the CNC machine control system, and perform CNC machining and manufacturing of the structural parts according to the process plan; before the finish machining of the second web surface in the machining process, call the in-machine measurement program for the web thickness to measure the web wall thickness, and transmit and store the measurement results to the industrial control computer.

8. A precise manufacturing method for the web of a large-scale double-sided structural member according to claim 7, characterized in that The specific content of (7) is as follows: Perform measurement result analysis and processing on the industrial control computer, evaluate the state of each web before final finishing in the web structure set F, and calculate the compensation strategy based on the evaluation state; analyze and calculate the wall thickness measurement results of each web surface in the web structure set one by one, evaluate the current processed wall thickness state of the web surface, and plan the corresponding compensation strategy according to the evaluation results; take the web f i For illustration: Hypothetical web structure set Middle web f i There are 3 wall thickness measurement points p i1 、p i2 、p i3 ,and the corresponding measured wall thickness values are δ i1 、δ i2 、δ i3 ,δ min and δ max respectively represent the minimum and maximum measured wall thickness values of the web surface. T min and T max respectively represent the allowable minimum and maximum design values of the web wall thickness. T represents the expected target thickness of the web, which is between the allowable maximum and minimum values. r represents the allowance before the finish machining of the web. k i represents the tool length compensation value corresponding to the machining of web f i , and H represents the actual tool length of the machining tool; (a) When δ min -T min < 0, it indicates that when the web is not finish-machined, the wall thickness has exceeded the allowable minimum value, and the part is out of tolerance and cannot be remedied; (b) When δ min -T min > 0 and δ min -r-T min ≤ 0 and δ max -r-T min ≤ 0, it indicates that all points on the web are too thin, and the wall thickness can be guaranteed by adding tool length compensation during machining. The tool compensation amount is k i = H + T min -(δ min -r); (c) When δ max -r-T max ≥ 0 and δ min -r-T max ≥ 0, it indicates that all points on the web are too thick, and compensation machining is carried out by increasing the tool compensation. When δ max -δ min ≤ T max -T min , the tool compensation amount is k i = H + T - (δ max -r); when δ max -δ min > T max -T min , the tool compensation amount is k i = H + T min -(δ min -r); (d) When T min ≤ δ min -r ≤ T max and T min ≤ δ max -r ≤ T max the thickness at the measuring point on the surface web plate is within the tolerance range, and no compensation machining is required; (e) When δ min -T min > 0 and δ min -r-T min ≤ 0 and δ max -r-T min ≥ 0, it indicates that some points on the web are thinner, some points are normal or thicker, and the tool compensation amount is k i = H + T min -(δ min -r); At this point, the web f is completed i Evaluate the current wall thickness status and plan corresponding compensation strategies based on the evaluation results.

9. A precise manufacturing method for the web of a large double-sided structural member according to claim 8, characterized in that The specific content of (8) is as follows: Complete the intelligent adjustment of the web finish machining program on the industrial control computer: Adjust the web machining program and the machining program of the sidewalls associated with the web one by one according to the web order in the web structure set F; first, according to the evaluation results in step (7), if the current web machining requires machining compensation, then perform program compensation adjustment on the current web finish machining program and the web-associated sidewall finish machining program; if no compensation needs to be added, do not modify the current web machining program and the web-associated sidewall machining program.

10. A precise manufacturing method for the web of a large-scale double-sided structural member according to claim 9, characterized in that, The specific content of (9) is as follows: Save the machining program adjusted in the previous step and import it into the CNC machining system, and call this program to complete the finish machining of the web surface, realizing the precise manufacturing of the web of large double-sided structural parts.

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