Large component involution skin edge milling method based on robot station transfer

Abstract

The invention discloses a large component involution skin edge milling method based on robot station transfer, and belongs to the technical field of aircraft assembly. The method comprises the following steps: firstly, establishing a coordinate system, positioning and measuring a skin A, then carrying out first-station fractional edge milling in an error compensation processing mode and a deformation compensation processing mode, carrying out transfer station positioning edge milling in the same mode, measuring the edge after edge milling of the skin A as an edge milling reference of the skin B, positioning and measuring the skin B after the skin A is moved out, and carrying out initial station edge milling and transfer station edge milling on the skin B in the same way, and finally folding the two skins. According to the method, through the technical application of unique system building reference, theoretical position on-rack machining of assembly stations, deformation compensation machining, error compensation machining and the like, large-part folding skin robot station-transferring automatic machining which is strict in skin joint tolerance requirement is achieved.

Description

Technical Field

[0001] The present invention belongs to the technical field of aircraft assembly, and relates to a method for milling the skin edges of large component joints based on a robot transfer station, and specifically to a method for automatically milling the skin edges of large aircraft component joints with high precision using a robot according to aircraft large component joint data. Background Art

[0002] With the rapid development of automation equipment, the field of aircraft assembly has gradually introduced automated skin edge milling robots to automate the processing of skin edges. Currently, the main application methods of automatic skin edge milling technology are: direct processing by robots according to data, and line-finding processing by robots using visual components.

[0003] The robot processes directly according to the data, which is suitable for small-sized parts-level processing. Due to the positioning error of the robot, the movement error of each joint of the robot, the deformation error of the tool and the skin, etc., the edge position of the panel after the robot station is processed is greatly different from the theoretical processing position. It is not suitable for skin edge milling that requires robot station transfer and skin matching positioning separately and has strict skin matching gap tolerance requirements.

[0004] The robot uses the visual component to find the line for processing. It is necessary to draw the cutting line position on the part with a pen first. The robot uses the visual line to find the line and cut the part. The milling task is completed by removing the line. However, due to the lack of precision in the thickness of the line traces and the accuracy of the line position (the tolerance of the manual line position is about 0.5mm), there is a certain gap between the processed parts and the expected ones (the error after processing is about 0.6mm~0.7mm). Due to the existence of manual lines, it is necessary to manually test the parts on the components first, determine the processing allowance, and draw the edge position of the allowance, resulting in the failure of the allowance milling to achieve true automation.

[0005] For large parts that require robot transfer processing and skin positioning in stages and have strict skin seam gap tolerance, after skin edge milling using the above processing method, the seam value cannot meet the control requirements. In order to meet the control status requirements, it is necessary to reserve processing allowances and manually supplement the skin edges when large parts are assembled. Summary of the invention

[0006] In view of the shortcomings of the current robot automatic milling technology in robot transfer milling and skin milling with strict requirements for seam gap tolerance, the present invention provides a large component joint skin milling method based on robot transfer for robot transfer and strict requirements for seam gap tolerance. By applying the technology of establishing a unique system reference, theoretical position frame processing of assembly stations, deformation compensation processing, error compensation processing, etc., the robot transfer automatic processing of large components with strict requirements for skin seam tolerance is realized. Although the present invention is aimed at the robot transfer automatic milling of the edge of the large component joint skin, the present invention is also applicable to the automatic milling of other skins with a joint relationship, as well as the high-precision processing of the edge position of a single skin, and the high-precision milling of the skeleton.

[0007] In order to achieve the above object, the technical solution of the present invention is:

[0008] A large component skinning edge milling method based on a robot transfer station, the edge milling method comprising the following steps:

[0009] Step 1: Establish a coordinate system

[0010] Fix the docking A skin and B skin on the skeleton of component A and component B respectively. The measuring equipment establishes the measurement coordinate system based on the four system reference points distributed on the ground around the workstation.

[0011] Step 2: Position and fix component A

[0012] Move the tooling carrying component A to the workstation, adjust the position and posture of component A to the theoretical position with the help of measuring equipment, and fix it.

[0013] Step 3: Measure the milling edge of skin A

[0014] The milling edge of skin A is measured using measuring equipment and compared with the theoretical edge of skin A to determine the milling value of skin A.

[0015] Step 4: A skin robot first station positioning and edge milling

[0016] According to the robot working parameters, the part of skin A to be cut is divided into multiple milling areas, the robot is moved to the workstation of the first milling area, and the coordinate system of the robot is established with the same system establishment reference as step 1.

[0017] According to the calculated cutting amount, the robot performs milling processing in batches through an error compensation processing method. The error compensation processing method refers to the problem that the actual measured value of the gap after processing deviates from the theoretical value due to the robot positioning error, measurement error and robot transfer processing. The adopted step-by-step milling method performs the next processing after measurement and calculation after each milling is completed. In addition, due to the extrusion between the milling cutter and the skin during the milling process, the skin produces a slight elastic deformation, and the milling cutter gives way. Therefore, each time milling is performed, the skin needs to be reverse milled along the processing path by the milling cutter to achieve deformation compensation processing for the deformation, and finally complete the milling of the A skin in this milling area.

[0018] Step 5: A skin robot transfers to position and mills the edges

[0019] Move the robot to the next area to be milled, and establish the coordinate system for the robot again using the same system establishment reference as step 1. The robot performs milling of the milling area in batches using error compensation processing to solve the problem of tool difference in transfer station and various errors, and each milling is performed with deformation compensation processing, specifically:

[0020] Initially measure the height difference h1 between the edge of the milling area to be milled and the edge of the previous milling area after milling at the tool connection position; calculate the processing value H1 according to the actual situation on the processing site (calculated on the principle that the protrusion of the butt edge is equal and the current processing amount is minimum), perform the first milling with the processing value H1, and perform deformation compensation processing.

[0021] Measure the height difference h2 between the edge after the first milling and the edge after the previous milling area again and calculate the processing value H2. Perform the second milling with the processing value H2 and perform deformation compensation processing. During the processing, use the value of h2-(h1-H1) as the compensation value for this milling to implement milling.

[0022] Perform multiple milling in the same way until the A skin in the current milling area is processed to the theoretical edge. The total number of milling times i is determined according to the actual processing situation, and i≥3; before each milling, measure the height difference h between the rear edge of the previous milling and the rear edge of the previous milling area. n , and calculate the processing value H n , with processing value H n Perform the nth milling and deformation compensation processing, where n = 1, 2, ..., i; during each processing, press h n -(h n-1 -H n-1 ) is used as the compensation value for the nth milling to perform milling processing.

[0023] Repeat step 5 until all milling areas of skin A are milled.

[0024] Step 6: Measure the edge position of part A after milling

[0025] Establish a coordinate system for the measuring equipment using the same system reference as in step 1, and measure the edge position of skin A after milling.

[0026] Step 7: Remove Part A

[0027] Move part A out of the workstation to make room for the robot to process part B.

[0028] Step 8: Position and fix component B

[0029] Move the tooling carrying part B to the workstation, establish a coordinate system for the measuring equipment using the same system building reference as in step 1, use the measuring equipment to adjust the position and posture of part B to the theoretical position, and fix it.

[0030] Step 9: Measure the milling edge of the B skin

[0031] Use the measuring equipment to measure the milling edge of the B skin, compare it with the rear edge position of the A skin after milling measured in step 6, and determine the milling value of the B skin.

[0032] Step 10, B skin robot first station positioning milling edge

[0033] According to the robot working parameters, the part of the B skin to be cut is divided into multiple milling areas, and the robot is moved to the workstation of the first milling area, and the robot coordinate system is established with the same system establishment reference as step 1. The B skin is milled at the first station using the same error compensation processing method as step 5; for the first milling area, the height difference and processing amount are calculated based on the edge of the A skin after milling.

[0034] Step 11, B skin robot transfer station positioning milling edge

[0035] Move the robot to the workstation of the next milling area, and establish the coordinate system of the robot with the same system reference as step 1. Use the same error compensation processing method as step 5 to perform milling processing on each milling area in turn to the theoretical position, and perform deformation compensation processing for each milling.

[0036] Repeat step 11 until all milling areas of skin B are milled.

[0037] Step 12: Align parts A and B

[0038] Move the robot out of the workstation, move the tooling carrying component A to the workstation, establish a coordinate system for the measuring equipment using the same system building reference as in step 1, and use the measuring equipment to adjust the position and posture of component A to the theoretical position to complete the alignment of components A and B.

[0039] Beneficial effects of the present invention:

[0040] The present invention solves the following problems that arise in robot edge milling technology:

[0041] (1) The robot is not suitable for skin edge milling, which requires the robot to transfer stations, position the skins separately and has strict tolerance requirements on the gap between the skins.

[0042] (2) When the robot uses the visual component to find the line for processing, it is necessary to manually draw the cutting line position on the part, and the milling edge position is not accurate enough.

[0043] (3) The present invention realizes high-precision edge milling of the skin even when the robot is rotating, eliminating the need for manual secondary repair of the skin when the components are aligned, and realizing truly automated processing of the robot-aligned skin. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] Figure 1 It is a schematic diagram of the principle of the present invention.

[0045] Figure 2 The robot performs the first station positioning and edge milling on the A skin.

[0046] Figure 3 The robot performs transfer positioning and edge milling on skin A.

[0047] Figure 4 It is a schematic diagram of the error compensation processing principle, where h1 is the height difference between the edge to be milled and the edge after milling in the previous milling area, h2 is the height difference between the edge after the first milling and the edge after milling in the previous milling area, and h3 is the height difference between the edge after the second milling and the edge after milling in the previous milling area; H1 and H2 are the first and second processing amounts, respectively.

[0048] Figure 5 The robot performs the first station positioning and edge milling on the B skin.

[0049] Figure 6 The robot performs transfer positioning and edge milling on the B skin.

[0050] In the figure: 1-A skin; 2-B skin; 3-reference point of system establishment; 4-robot; DETAILED DESCRIPTION

[0051] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the specific implementation methods of the present invention will be described in detail below with reference to the technical solution.

[0052] This embodiment provides a large component joint skin milling method based on a robot transfer station. The principle is as follows Figure 1 As shown, the edge milling method comprises the following steps:

[0053] Step 1: Establish a coordinate system

[0054] The A skin 1 and the B skin 2 in docking relationship are fixed on the skeletons of the A component and the B component respectively. The measuring equipment establishes a measurement coordinate system using four system reference points 3 distributed on the ground around the workstation as system references.

[0055] Step 2: Position and fix component A

[0056] Move the tooling carrying component A to the workstation, adjust the position and posture of component A to the theoretical position with the help of measuring equipment, and fix it.

[0057] Step 3: Measure the milling edge of skin A 1

[0058] The milling edge of skin A 1 is measured by measuring equipment and compared with the theoretical edge of skin A 1 to determine the milling value of skin A 1.

[0059] Step 4: A skin robot first station positioning and edge milling

[0060] like Figure 2 As shown, according to the working parameters of the robot 4, such as the robot arm length, the part of the A skin 1 to be cut is divided into two milling areas, the robot 4 is moved to the work station of the first milling area, and the coordinate system of the robot 4 is established with the same system establishment reference as step 1.

[0061] According to the calculated cutting amount, the robot 4 performs milling processing in stages through an error compensation processing method. The error compensation processing method refers to the problem that the actual measured value of the gap after processing deviates from the theoretical value due to the positioning error, measurement error and tool connection difference of the robot 4 transfer processing, and the adopted step-by-step milling method is measured and calculated again after each milling is completed; in addition, due to the extrusion between the milling cutter and the skin during the milling process, the skin produces a slight elastic deformation, and the milling cutter gives way. Therefore, each time milling is performed, the skin needs to be reverse milled along the processing path by the milling cutter to achieve deformation compensation processing for the deformation, and finally the milling of the A skin 1 in the first milling area is completed.

[0062] Step 5: A skin robot transfers to position and mills the edges

[0063] like Figure 3 As shown, the robot 4 is moved to the second milling area, and the coordinate system of the robot 4 is established again with the same system establishment reference as step 1. The robot 4 performs milling processing in this milling area in batches by error compensation processing to solve the problem of tool difference in transfer station and various errors, and deformation compensation processing is performed for each milling, such as Figure 4 As shown, specifically:

[0064] Initially measure the height difference h1 between the edge of the milling area to be milled and the edge of the previous milling area after milling at the tool connection position; calculate the processing value H1 according to the actual situation on the processing site (calculated on the principle that the protrusion of the butt edge is equal and the current processing amount is minimum), perform the first milling with the processing value H1, and perform deformation compensation processing.

[0065] Measure the height difference h2 between the edge after the first milling and the edge after the previous milling area again and calculate the processing value H2. Perform the second milling with the processing value H2 and perform deformation compensation processing. During the processing, use the value of h2-(h1-H1) as the compensation value for this milling to implement milling.

[0066] Perform multiple milling in the same way until the A skin 1 in the current milling area is processed to the theoretical edge. The total number of milling times i is determined according to the actual processing situation, and i ≥ 3; before each milling, measure the height difference h between the rear edge of the previous milling and the rear edge of the previous milling area. n , and calculate the processing value H n , with processing value H n Perform the nth milling and deformation compensation processing, where n = 1, 2, ..., i; during each processing, press h n -(h n-1 -H n-1 ) is used as the compensation value for the nth milling to implement the milling process. In this embodiment, the milling is performed in 3 times.

[0067] Step 6: Measure the edge position of part A after milling

[0068] Establish a coordinate system for the measuring equipment using the same system establishment reference as in step 1, and measure the edge position of skin A 1 after milling.

[0069] Step 7: Remove Part A

[0070] Move part A out of the workstation to make room for robot 4 to process part B.

[0071] Step 8: Position and fix component B

[0072] Move the tooling carrying part B to the workstation, establish a coordinate system for the measuring equipment using the same system building reference as in step 1, use the measuring equipment to adjust the position and posture of part B to the theoretical position, and fix it.

[0073] Step 9: Measure the milling edge of skin B 2

[0074] Use the measuring equipment to measure the milling edge of B skin 2, compare it with the milling edge position of A skin 1 measured in step 6, and determine the milling value of B skin 2.

[0075] Step 10, B skin robot first station positioning milling edge

[0076] like Figure 5 As shown, according to the working parameters of robot 4, the part to be cut of B skin 2 is divided into two milling areas, and robot 4 is moved to the workstation of the first milling area, and the coordinate system of robot 4 is established with the same system establishment reference as step 1. The first milling of B skin 2 is performed using the same error compensation processing method as step 5; for the first milling area, the height difference and processing amount are calculated based on the milled edge of A skin 1.

[0077] Step 11, B skin robot transfer station positioning milling edge

[0078] like Figure 6 As shown, the robot 4 is moved to the workstation of the next milling area, and the coordinate system of the robot 4 is established with the same system establishment reference as step 1. The same error compensation processing method as step 5 is used to perform milling processing on each milling area in turn to the theoretical position, and deformation compensation processing is performed for each milling.

[0079] Repeat step 11 until the milling process of all milling areas of skin B 2 is completed.

[0080] Step 12: Align parts A and B

[0081] Move robot 4 out of the workstation, move the tooling carrying component A to the workstation, establish a coordinate system for the measuring equipment with the same system building reference as step 1, use the measuring equipment to adjust the position and posture of component A to the theoretical position, and complete the alignment of components A and B.

[0082] The innovation of the present invention is:

[0083] (1) Unique system building benchmark

[0084] The measurement equipment system, robot system, etc. all use the same system reference (the aircraft coordinate system) at the assembly station.

[0085] (2) Theoretical position of assembly station on-frame processing

[0086] The two matched parts are both processed at the workstation and are processed on the rack in a matched posture. When one part is processed, the other part is moved out a proper distance to provide working space. The processed state of the first part serves as the basis for the processing of the other part.

[0087] (3) Deformation compensation processing

[0088] During the milling process, due to the extrusion between the milling cutter and the skin, the skin undergoes a slight elastic deformation, and the milling cutter gives way. The milling cutter needs to reverse mill the skin along the processing path to compensate for the deformation.

[0089] (4) Error compensation processing

[0090] Due to the occurrence of various errors such as robot positioning error and measurement error, the robot transfer processing produces a tool connection error problem; after using deformation compensation processing, the gap value between the docking skins still deviates from the theoretical requirement. To solve these two problems, the error compensation processing method of measurement, calculation, and multi-step processing is adopted.

Claims

1. A method for milling the skin of large parts based on a robot transfer station, characterized in that: First, establish a coordinate system, position and fix component A, measure the milling edge of skin A 1, robot 4 performs first station and transfer station positioning and milling on skin A 1, measure the edge position after milling of skin A 1, position and fix component B, measure the milling edge of skin B 2, robot 4 performs first station and transfer station positioning and milling on skin B 2, and finally align components A and B.

2. According to the method of large component skinning and edge milling based on robot transfer station in claim 1, it is characterized in that: The edge milling method specifically comprises the following steps: Step 1: Establish the coordinate system Fix the A skin 1 and B skin 2 in a docking relationship on the skeletons of the A component and the B component respectively, and use the four system reference points 3 distributed on the ground around the workstation as the system reference to establish a measurement coordinate system; Step 2: Position and fix component A Move the tooling carrying component A to the workstation, adjust the position and posture of component A to the theoretical position with the help of measuring equipment, and fix it; Step 3: Measure the milling edge of skin A 1 Use measuring equipment to measure the milling edge of skin A 1, and compare it with the theoretical edge of skin A 1 to determine the milling value of skin A 1; Step 4, A skin 1 robot 4 first station positioning milling edge The portion of the A skin 1 to be cut is divided into a plurality of milling areas, the robot 4 is moved to the workstation of the first milling area, and a coordinate system is established for the robot 4 using the same system establishment reference as in step 1; According to the calculated cutting amount, the robot 4 performs milling processing in stages by means of error compensation processing. In addition, deformation compensation processing is performed during each milling, and finally the milling of the A skin 1 in the current milling area is completed; Step 5, A skin 1 robot 4 transfer station positioning milling edge Move the robot 4 to the next area to be milled, and establish the coordinate system for the robot 4 again with the same system establishment reference as step 1; the robot 4 performs milling processing in this milling area in batches by using the error compensation processing method to solve the problem of tool difference in transfer station and various errors, and deformation compensation processing is performed for each milling; Repeat step 5 until the milling process of all the milling areas of skin A 1 is completed; Step 6: Measure the edge position of part A after milling Establish a coordinate system for the measuring equipment using the same system establishment reference as in step 1, and measure the edge position of skin A 1 after edge milling; Step 7: Remove Part A Move part A out of the workstation to make room for robot 4 to process part B; Step 8: Position and fix component B Move the tooling carrying component B to the workstation, establish a coordinate system for the measuring device using the same system building reference as in step 1, adjust the position and posture of component B to the theoretical position with the help of the measuring device, and fix it; Step 9: Measure the milling edge of skin B 2 Use the measuring equipment to measure the milling edge of the B skin 2, compare it with the edge position after the milling of the A skin 1 measured in step 6, and determine the milling value of the B skin 2; Step 10, B skin 2 robot 4 first station positioning milling edge The part of the B skin 2 to be cut is divided into multiple milling areas, the robot 4 is moved to the workstation of the first milling area, and the coordinate system of the robot 4 is established with the same system establishment reference as step 1; the B skin 2 is milled at the first station using the same error compensation processing method as step 5; Step 11, B skin 2 robot 4 transfer station positioning milling edge Move the robot 4 to the workstation of the next milling area, and establish a coordinate system for the robot 4 using the same system establishment reference as in step 1; use the same error compensation processing method as in step 5 to perform milling processing on each milling area in turn to the theoretical position, and perform deformation compensation processing for each milling; Repeat step 11 until the milling process of all the milling areas of skin B 2 is completed; Step 12: Align parts A and B Move robot 4 out of the workstation, move the tooling carrying component A to the workstation, establish a coordinate system for the measuring equipment with the same system building reference as step 1, use the measuring equipment to adjust the position and posture of component A to the theoretical position, and complete the alignment of components A and B.

3. The method for milling the skin of a large component based on a robot transfer station according to claim 2 is characterized in that: In the step 4, the number of milling areas into which the portion of the skin 1 to be cut is divided is determined according to the working parameters of the robot 4.

4. The method for milling the skin of a large component based on a robot transfer station according to claim 2 is characterized in that: In step 4, the error compensation processing method refers to the problem that the actual measured value of the gap after processing deviates from the theoretical value due to the processing error of the robot 4, and the multi-step milling method is adopted. After each milling is completed, the next processing is carried out after measurement and calculation.

5. The method for milling the skin of a large component based on a robot transfer station according to claim 2 is characterized in that: In the step 4, the deformation compensation processing method is: the milling cutter reversely mills the skin along the processing path.

6. The method for milling the skin of a large component based on a robot transfer station according to claim 2 is characterized in that: The specific process of step 5 is as follows: Initially measure the height difference h1 between the edge of the current milling area to be milled and the edge of the previous milling area after milling at the tool connection position; calculate the processing value H1 according to the actual situation at the processing site, perform the first milling with the processing value H1, and perform deformation compensation processing; The height difference h2 between the first milling edge and the previous milling area is measured again and the processing value H2 is calculated. The second milling is performed with the processing value H2, and deformation compensation processing is performed. During the processing, the milling process is performed according to the value of h2-(h1-H1) as the compensation value of this milling. Perform multiple milling in the same way until the A skin 1 in the current milling area is processed to the theoretical edge. The total number of milling times i is determined according to the actual processing situation. Before each milling, measure the height difference h between the rear edge of the previous milling and the rear edge of the previous milling area. n , and calculate the processing value H n , with processing value H n Perform the nth milling and deformation compensation processing, where n = 1, 2, ..., i; during each processing, press h n -(h n-1 -H n-1 ) is used as the compensation value for the nth milling to perform milling processing.

7. The method for milling the skin of a large component based on a robot transfer station according to claim 6 is characterized in that: The processing value H1 is calculated based on the principle that the extension of the butt edges is equal and the processing amount is minimal.

8. The method for milling the skin of a large component based on a robot transfer station according to claim 6 is characterized in that: The total number of milling cuts i≥3.

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