Method for optimizing complex titanium lamination hole making process of automatic equipment

Abstract

The invention relates to the field of aircraft assembling and manufacturing, in particular to a method for optimizing a complex titanium lamination hole making process of automatic equipment. The method comprises the following steps: firstly, establishing a finite element simulation model on the basis of an automatic equipment complex titanium lamination hole making working condition, and simulating the complex titanium lamination hole making working conditions of different machining modes, cutter parameters and cutting parameters; according to the simulation result, the optimal machining mode is selected, and the influence rule of cutting parameters and cutter parameters on the cutting force is studied. And based on the simulation result, carrying out a research and development test on the special cutter for the composite titanium laminated hole making, selecting optimal cutter parameters and cutting parameters, and completing research and development of the special cutter. After research and development of the special cutter are completed, a cutter abrasion test is carried out, and the abrasion morphology and the abrasion rule of the cutter are researched. And a drilling quality optimization test is carried out, and the influence rule of the cutter parameters and the cutting parameters on the drilling quality is studied.

Description

Technical Field

[0001] The invention relates to the field of aircraft assembly manufacturing, and in particular to a method for optimizing a titanium composite lamination hole-making process for automated equipment. Background Art

[0002] Carbon fiber composite materials are lightweight and high-strength, and titanium alloy materials are high hardness and high temperature resistance. In the design stage of aircraft products, carbon fiber composite materials and titanium alloy materials are often widely used. Therefore, in the assembly process of aircraft products, a large number of complex titanium laminated hole making conditions will inevitably appear.

[0003] Carbon fiber composite materials are typical anisotropic materials. During the hole processing, it is very easy to produce defects such as tearing, delamination, and burrs. Titanium alloys have large cutting forces and high cutting temperatures during drilling, which makes it easier to produce chip entanglement and built-up edge. Both carbon fiber composite materials and titanium alloys are typical difficult-to-process materials.

[0004] For the hole-making condition of titanium composite laminate, the traditional manual hole-making method is generally used: workers use the traditional drilling-expansion-reaming process to gradually complete the laminate hole-making work. The above method has low hole-making efficiency, requires more tools, the hole-making quality is not stable enough, and the labor intensity of workers is high. It is urgent to adopt a new process method with high efficiency and high precision to replace this hole-making method.

[0005] In order to improve the assembly efficiency of aircraft products and realize the goal of digitalization and intelligentization of aircraft product assembly, a large number of automated equipment have been introduced into the aircraft assembly production line. Compared with traditional manual hole making, automated hole making has the advantages of high hole making efficiency, stable hole making quality, and low labor intensity. However, the processing difficulties of composite titanium laminate hole making still exist in the process of automated hole making. In addition, in the traditional manual composite titanium laminate hole making, the traditional drilling-expansion-reaming process method is often used, which requires more tools and takes a long time. In order to improve the processing efficiency, it is generally required that the automated equipment make the final hole in one cut, which puts higher requirements on the automated hole making tools and process methods.

[0006] At present, for the condition of making holes in titanium composite laminates in open areas of aircraft, automated hole making equipment can be used to replace traditional hole making methods. Automated hole making equipment usually makes the final hole in one cut, with high processing efficiency. However, according to the on-site knife test, there are still problems such as composite material delamination and splitting, poor hole making accuracy, severe tool wear and low tool life.

[0007] Based on the above situation, before the automated equipment for titanium composite laminated hole making, it is necessary to develop an automated equipment for titanium composite laminated hole making process optimization method to optimize the hole making quality, increase tool life, and speed up the hole making efficiency, thereby improving the assembly quality and efficiency of aircraft products. Summary of the invention

[0008] In order to solve the above technical problems, the present invention provides a method for optimizing the hole-making process of titanium composite lamination using automated equipment.

[0009] The technical solution of the present invention is as follows:

[0010] Based on the working conditions of titanium composite laminate hole making in automated equipment, a finite element simulation model is first established to simulate the working conditions of titanium composite laminate hole making with different processing methods, tool parameters, and cutting parameters. According to the simulation results, the best processing method is selected, and the influence of cutting parameters and tool parameters on cutting force is studied. Based on the simulation results, a special tool research and development test for titanium composite laminate hole making is carried out, the best tool parameters and cutting parameters are selected, and the research and development of special tools is completed. After the development of special tools is completed, tool wear tests are carried out to study the tool wear morphology and wear law. Hole making quality optimization tests are carried out to study the influence of tool parameters and cutting parameters on hole making quality.

[0011] A method for optimizing the hole-making process of titanium composite laminates in automated equipment mainly consists of four main parts: 1. simulation analysis of titanium composite laminate hole-making; 2. research and development of special tools for titanium composite laminate hole-making; 3. research on wear law of tools for titanium composite laminate hole-making; and 4. research on quality optimization of titanium composite laminate hole-making.

[0012] 1. The simulation analysis of hole making in composite titanium laminated layers consists of four steps: 1-1 establishing a simulation model; 1-2 simulation analysis of different processing methods; 1-3 simulation analysis of different tool parameters; 1-4 simulation analysis of different cutting parameters.

[0013] 1-1 The simulation model is established through the finite element simulation software abaqus. The materials are set to carbon fiber and titanium alloy. The T800 material damage model is defined by the user material, and the titanium alloy material damage model uses the Johnson-Cook damage model.

[0014] The total length, total width, total height and number of plies of the composite material constitutive model are input through Abaqus scripts written in Python, and the purpose of automatically generating the constitutive model and allocating the cross-section of each layer of material is achieved. The input parameters are the overall size: total length 30mm, total width 30mm, CFRP layer thickness 8mm, and number of plies is 10. On the basis of the original, the titanium layer model is established using the stretching function and the corresponding cross-sectional properties are assigned to it. The fiber direction of the CFRP laminate material is created based on the global coordinate system to achieve the simulation of the anisotropy of the CFRP material. Each layer is orthogonally defined in the 0° / 90° direction.

[0015] Create a dynamic-display analysis step and set the analysis step time to 0.01. In order to shorten the calculation time and improve the calculation efficiency, turn on mass scaling in the simulation and set the mass scaling factor to 100. At the same time, a smaller scaling factor will ensure the accuracy of the simulation results.

[0016] The material mesh is divided into hexahedrons, eight-node linear hexahedron elements, reduced integral, hourglass control, and element deletion to generate the sample mesh. The tool mesh is divided into four-node linear tetrahedron elements.

[0017] The simulation needs to run through the entire sheet metal model, so the definition of interaction requires the interaction between the tool surface and the contact node. First, establish the contact mode, set the tangential friction coefficient to 0.2, and the normal contact to hard contact. Use the collar to select the area nodes with a larger tool contact range and create a node set. This method minimizes the simulation calculation time and improves the simulation efficiency while fully defining the contact.

[0018] Tool displacement is realized by amplitude. Since the total time of the analysis step is set to 0.01 above, the table amplitude is used for definition. When the analysis time is 0.01, the tool displacement increases linearly from 0 to the load definition value.

[0019] 1-2 The simulation analysis of different processing methods mainly simulates and analyzes the three hole-making methods of traditional drilling, spiral milling and low-frequency vibration-assisted hole-making. First, the advantages and disadvantages of the three hole-making methods are comprehensively compared: for the hole-making process of automated equipment for aircraft parts, for traditional drilling hole-making, the advantages are high processing efficiency, drilling and countersinking can be performed at the same time, the equipment adaptability is strong, and the processing cost is low; the disadvantages are low tool life and poor hole-making quality assurance. For spiral milling, its advantages are good hole-making quality and high hole-making life; the disadvantages are low processing efficiency and long time consumption, countersinking cannot be performed, high rigidity requirements for hole-making equipment, and the automatic hole-making equipment needs to have a spiral milling unit, and the versatility is general. For low-frequency vibration-assisted hole-making, its advantages are good hole-making quality and good chip breaking effect for titanium alloy processing; the disadvantages are that the purchase price of low-frequency vibration auxiliary equipment is relatively expensive, and the existing equipment needs to be modified, the existing equipment has poor adaptability, and the use cost is relatively high.

[0020] In order to select the optimal processing method, the established titanium composite stack simulation model was used to simulate the above three processing methods using the same existing cutting parameters and tool parameters. After the simulation was completed, the axial forces were analyzed respectively.

[0021] 1-3 Simulation analysis of different tool parameters is set to simulate the hole-making condition of composite titanium laminated materials under different tool parameters after simulation analysis of different processing methods in 1-2, that is, when the best processing method has been selected. The three important parameters of drill bit front angle, back angle and helix angle are selected for analysis to study their main influence on the drilling of laminated materials. The simulation adopts the orthogonal test method to generate multiple groups of parameter combinations, and each group of parameter combinations is simulated and analyzed separately.

[0022] 1-4 Simulation analysis of different cutting parameters is set to simulate the hole-making condition of composite titanium laminate under different cutting parameters after the simulation analysis of different tool parameters in 1-3, that is, when the best tool parameters have been selected. The two important parameters of rotation speed and feed rate are selected for analysis to study their main influence on the drilling of laminated materials. The simulation adopts the method of single factor experiment to generate multiple groups of parameter combinations, and each group of parameter combinations is simulated and analyzed separately. After the simulation is completed, the axial drilling force, stress, cutting temperature and other factors of each group of parameters are compared to select the appropriate tool parameters.

[0023] 2. Research and development of special tools for hole making in complex titanium laminated layers is set up to verify the simulation results and complete the research and development of special tools for hole making in complex titanium laminated layers after 1. Simulation analysis of hole making in complex titanium laminated layers. 2. Research and development of special tools for hole making in complex titanium laminated layers is mainly divided into 2-1 test condition preparation, 2-2 tool parameter optimization test, and 2-3 cutting parameter optimization test.

[0024] 2-1 Preparation of test conditions: The workpiece materials selected for the test are carbon fiber composite materials and titanium alloy laminates. The size of the composite material sheet is 300×300mm and the thickness is 8mm; the size of the titanium alloy sheet is 300×300mm and the thickness is 6mm. Combining theoretical analysis and simulation results, the test tool is selected. The stacking drilling test was carried out using tools generated by the same manufacturer and the same batch to study the changes in drilling force and tool wear under different tool parameters. In the process of experimental research, in order to truly reflect the changes in drilling force and tool wear under different tool parameters, the drilling force during the processing of each hole was measured, and the tool wear was studied by measuring once every five holes.

[0025] During the drilling process, the axial drilling force is detected in real time by the force measuring system, and the tool wear of the tool is measured by using an ultra-depth-of-field microscope.

[0026] 2-2 Tool parameter optimization test is set up to select appropriate tool parameters for complex titanium laminate hole making. The test adopts the method of single factor test, and uses drills with different drill bit angles, back angles, and helix angles to conduct complex titanium laminate hole making tests. During the test, the axial drilling force under different tool parameters is recorded. After the test, the influence of tool parameters on the axial drilling force is analyzed to select the best tool parameters.

[0027] The 2-3 cutting parameter optimization test is set up to select the appropriate cutting parameters for complex titanium laminated hole making. After the best tool parameters are selected in the 2-2 tool parameter optimization test, the tool with the tool parameters is selected, and the single factor test method is adopted to carry out the complex titanium laminated hole making test with different cutting parameters. The axial drilling force of different cutting parameter tests is recorded during the test. After the test, the influence of cutting parameters on the axial drilling force is analyzed to select the best cutting parameters.

[0028] 3. The research on tool wear law of composite titanium laminate hole making is to study the influence of cutting parameters on tool wear process and tool wear morphology in composite titanium laminate hole making process. 3. The research on tool wear law of composite titanium laminate hole making consists of 3-1 research on the relationship between tool wear and cutting parameters and 3-2 research on tool wear morphology in drilling process.

[0029] 3-1 Research on the relationship between tool wear and cutting parameters The single factor test method was adopted to select different cutting parameters for the titanium composite layer hole making test. During the test, the cutting edge wear was photographed with an ultra-depth of field microscope after drilling five holes, and the tool wear was recorded to compare and analyze the influence of cutting parameters on tool wear. The tool wear morphology photos taken with the ultra-depth of field microscope were used to compare and observe the changes in the wear of the tool outer edge corner after drilling the 10th, 20th, 30th, and 40th holes, and the tool wear morphology of the drilling process was studied in 3-2.

[0030] 4. The optimization study of hole making quality of composite titanium laminates is designed to study the influence of tool parameters and cutting parameters on hole making quality (such as the degree of tearing around the composite hole, the height of burrs at the exit of titanium alloy holes, surface roughness, and hole making accuracy). 4. The optimization study of hole making quality of composite titanium laminates is divided into two parts: 4-1 Study on the relationship between hole making quality and tool parameters and 4-2 Study on the relationship between hole making quality and cutting parameters.

[0031] 4-1 Study on the relationship between hole quality and tool parameters The single factor test method was used to conduct composite titanium stack drilling tests using tools with different parameters. An ultra-depth microscope was used to observe the degree of tearing around the composite hole under different tool parameters. A micrometer was used to measure the burr height and aperture accuracy of the titanium alloy hole outlet under different tool parameters. A roughness measuring instrument was used to measure the roughness of the hole wall under different tool parameters.

[0032] 4-2 Study on the relationship between hole quality and cutting parameters The single-factor experimental method was used to carry out composite titanium laminate drilling tests using different cutting parameters. An ultra-depth-of-field microscope was used to observe the degree of tearing around the composite hole under different cutting parameters. A micrometer was used to measure the burr height at the titanium alloy hole exit and the aperture accuracy under different cutting parameters. A roughness measuring instrument was used to measure the hole wall roughness under different cutting parameters.

[0033] The beneficial effects brought by the present invention are:

[0034] 1. Through this process optimization method, the tool parameters and cutting parameters of the automated equipment for titanium composite lamination hole making are improved, the hole making quality is optimized, the tool life is increased, and the hole making efficiency is accelerated. The assembly quality and efficiency of aircraft products are improved.

[0035] 2. This process method provides experience and guidance for the optimization of subsequent related hole-making processes. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] like Figure 1 Shown is a schematic diagram of the drilling force measurement system used in the experiment;

[0037] like Figure 2 Shown is a schematic diagram of tool cutting edge wear. DETAILED DESCRIPTION

[0038] The specific implementation methods and steps of the present invention are as follows:

[0039] 1. Use the developed special tool for making holes in titanium composite layers to start the test of the tool for making holes in titanium composite layers in automated equipment;

[0040] 2. After the special tool is delivered, check the appearance of the special tool, especially the cutting edge, to ensure that the tool is brand new, unused and intact;

[0041] 3. Prepare the test plate for knife testing and fix it firmly;

[0042] 4. Start the automatic hole-making equipment, install the special tool on the equipment spindle, and debug the equipment to the processing state.

[0043] 5. Perform offline programming of the equipment according to the test plate and tool status, and input appropriate cutting parameters obtained from the test.

[0044] 6. After all aspects are checked, turn on the automatic hole making equipment and start the knife test. During the knife test, the process personnel need to stand by and observe the drilling situation. If there is any abnormality, stop the knife test in time.

[0045] 7. After the test cutter is completed, check the condition of the tool and the quality of the hole.

[0046] Finally, the present invention is not limited to the above description, but may include any variant solutions falling within the scope defined in the description.

Claims

1. A method for optimizing the hole-making process of titanium composite lamination in automated equipment, characterized in that: Here are the steps: Step 1: Simulation analysis of hole making in titanium composite laminated layers; Step 2: Research and development of special tools for making holes in composite titanium laminated layers; Step 3: Study on the wear law of titanium composite laminated hole-making tools; Step 4: Research on optimization of hole making quality of titanium composite laminate; The first step of the simulation analysis of the hole making of the titanium composite layer includes four steps: 1-1 establishing a simulation model; 1-2 simulation analysis of different processing methods; 1-3 simulation analysis of different tool parameters; 1-4 simulation analysis of different cutting parameters; 1-1 The simulation model is established by using the finite element simulation software abaqus. The materials are set to carbon fiber and titanium alloy. The damage model of T800 material is defined by the user material, and the damage model of titanium alloy material uses the Johnson-Cook damage model. The Abaqus script written in Python is used to input the total length, total width, total height and number of layers of the composite material constitutive model, automatically generate the constitutive model and allocate the cross section of each layer of material; the input parameters are the overall size: total length 30mm, total width 30mm, CFRP layer thickness 8mm, and number of layers 10; on the basis of the original, the titanium layer model is established using the stretching function and the corresponding cross-sectional properties are assigned to it; the fiber direction of the CFRP laminate material is created based on the global coordinate system to achieve the simulation of the anisotropy of the CFRP material; each layer is orthogonally defined in the 0° / 90° direction; Create dynamics-display analysis step, set the analysis step time to 0.01, and in order to shorten the calculation time and improve the calculation efficiency, turn on the mass scaling of the simulation and set the mass scaling factor to 100. At the same time, a smaller scaling factor will ensure the accuracy of the simulation results; The material mesh is divided into hexahedrons, eight-node linear hexahedron elements, reduced integral, hourglass control, and element deletion, and the sample mesh is generated. The tool mesh is divided into four-node linear tetrahedron elements. The simulation needs to run through the entire sheet metal model, so the definition of interaction requires the interaction between the tool surface and the contact node; first establish the contact mode, set the tangential friction coefficient to 0.2, and the normal contact to hard contact; use the collar to select the area nodes with a larger tool contact range and create a node set; the tool displacement is realized by the amplitude; 1-2 Simulation analysis of different processing methods is to simulate and analyze three hole-making methods: traditional drilling, spiral milling and low-frequency vibration-assisted hole-making; Using the established simulation model of titanium composite laminate, the above three processing methods are simulated respectively with the same existing cutting parameters and tool parameters; after the simulation is completed, the axial forces are analyzed respectively; 1-3 Simulation analysis of different tool parameters is set to simulate the hole-making condition of composite titanium laminated materials under different tool parameters after simulation analysis of different processing methods in 1-2, that is, when the best processing method has been selected; three important parameters, namely, drill bit front angle, back angle and helix angle, are selected for analysis to study their main influence on the drilling of laminated materials; the simulation adopts the orthogonal test method to generate multiple groups of parameter combinations, and each group of parameter combinations is simulated and analyzed respectively; 1-4 Simulation analysis of different cutting parameters is set after 1-3 simulation analysis of different tool parameters, that is, when the best tool parameters have been selected, in order to simulate the hole-making working condition of the composite titanium laminate under different cutting parameters; the two important parameters of rotation speed and feed rate are selected for analysis.

2. The method for optimizing the hole-making process of titanium composite laminated automated equipment according to claim 1, characterized in that: The second step of developing a special tool for making holes in titanium composite laminates includes 2-1 test condition preparation, 2-2 tool parameter optimization test, and 2-3 cutting parameter optimization test; 2-1 Test conditions preparation: The workpiece materials selected for the test are carbon fiber composite materials and titanium alloy laminated plates; the composite material sheet size is 300×300mm and the thickness is 8mm; the titanium alloy sheet size is 300×300mm and the thickness is 6mm; the test tool is selected based on the theoretical analysis and simulation results; 2-2 The tool parameter optimization test is set up to select the appropriate tool parameters for complex titanium laminated hole making. The test adopts the single factor test method, and uses drills with different drill bit edge angles, back angles, and helix angles to conduct complex titanium laminated hole making tests. During the test, the axial drilling force under different tool parameters is recorded, and after the test, the influence of tool parameters on the axial drilling force is analyzed to select the best tool parameters. The 2-3 cutting parameter optimization test is set up to select appropriate cutting parameters for complex titanium laminated hole making. After the best tool parameters are selected in the 2-2 tool parameter optimization test, the tool with this tool parameter is selected, and the single factor test method is adopted to carry out the complex titanium laminated hole making test with different cutting parameters. During the test, the axial drilling force of the tests with different cutting parameters is recorded, and the influence of the cutting parameters on the axial drilling force is analyzed after the test to select the best cutting parameters.

3. The method for optimizing the hole-making process of titanium composite laminated layers in automated equipment according to claim 1 or 2, characterized in that: The third step of the titanium composite laminate hole-making tool wear law study includes 3-1 tool wear and cutting parameter relationship study, 3-2 drilling process tool wear morphology study; 3-1 Study on the relationship between tool wear and cutting parameters The single factor test method was adopted, and different cutting parameters were selected for the complex titanium laminated hole making test; during the test, the cutting edge wear was photographed with an ultra-depth of field microscope after drilling every five holes, and the tool wear amount was recorded to compare and analyze the influence of cutting parameters on tool wear; using the tool wear morphology photos taken with the ultra-depth of field microscope, the changes in the wear of the tool outer edge corner after drilling the 10th, 20th, 30th, and 40th holes were compared and observed, and the tool wear morphology of the drilling process 3-2 was studied.

4. The method for optimizing the hole-making process of titanium composite laminated layers in automated equipment according to claim 1 or 2, characterized in that: The fourth step of the optimization study of the hole making quality of the titanium composite laminate includes 4-1 the study of the relationship between the hole making quality and the tool parameters and 4-2 the study of the relationship between the hole making quality and the cutting parameters; 4-1 Study on the relationship between hole quality and tool parameters The single factor test method was used to conduct composite titanium stack drilling tests using tools with different parameters. An ultra-depth microscope was used to observe the degree of tearing around the composite hole under different tool parameters. A micrometer was used to measure the burr height at the titanium alloy hole outlet and the aperture accuracy under different tool parameters. A roughness measuring instrument was used to measure the hole wall roughness under different tool parameters. 4-2 Study on the relationship between hole quality and cutting parameters The single-factor experimental method was used to carry out composite titanium laminate drilling tests using different cutting parameters. An ultra-depth-of-field microscope was used to observe the degree of tearing around the composite hole under different cutting parameters. A micrometer was used to measure the burr height at the titanium alloy hole exit and the aperture accuracy under different cutting parameters. A roughness measuring instrument was used to measure the hole wall roughness under different cutting parameters.

5. The method for optimizing the hole-making process of titanium composite laminated layers in automated equipment according to claim 3, characterized in that: The fourth step of the optimization study of the hole making quality of the titanium composite laminate includes 4-1 the study of the relationship between the hole making quality and the tool parameters and 4-2 the study of the relationship between the hole making quality and the cutting parameters; 4-1 Study on the relationship between hole quality and tool parameters The single factor test method was used to conduct composite titanium stack drilling tests using tools with different parameters. An ultra-depth microscope was used to observe the degree of tearing around the composite hole under different tool parameters. A micrometer was used to measure the burr height at the titanium alloy hole outlet and the aperture accuracy under different tool parameters. A roughness measuring instrument was used to measure the hole wall roughness under different tool parameters. 4-2 Study on the relationship between hole quality and cutting parameters The single-factor experimental method was used to carry out composite titanium laminate drilling tests using different cutting parameters. An ultra-depth-of-field microscope was used to observe the degree of tearing around the composite hole under different cutting parameters. A micrometer was used to measure the burr height at the titanium alloy hole exit and the aperture accuracy under different cutting parameters. A roughness measuring instrument was used to measure the hole wall roughness under different cutting parameters.

6. The method for optimizing the hole-making process of titanium composite laminated layers in automated equipment according to claim 2, characterized in that: In the preparation of the test conditions 2-1, a stacked drilling test was carried out using tools produced by the same manufacturer and the same batch to study the changing patterns of drilling force and tool wear under different tool parameters. During the experimental study, in order to truly reflect the changes in drilling force and tool wear under different tool parameters, the drilling force during the processing of each hole was measured, and the study of tool wear was carried out by measuring once every five holes.

7. The method for optimizing the hole-making process of titanium composite laminated layers in automated equipment according to claim 6, characterized in that: During the drilling process, the axial drilling force is detected in real time by the force measuring system, and the tool wear of the tool is measured by using an ultra-depth-of-field microscope.

8. The method for optimizing the hole-making process of titanium composite laminated layers in automated equipment according to claim 1, characterized in that: In the steps 1-4, the simulation adopts a single factor test method to generate multiple groups of parameter combinations, and each group of parameter combinations is simulated and analyzed separately; after the simulation is completed, the axial drilling force, stress, cutting temperature and other factors of each group of parameters are compared to select the tool parameters.

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