Titanium repositioning and stacking layer hole drilling process optimization method of automation equipment

Abstract

The present application relates to the field of aircraft assembly manufacturing, in particular to a kind of automatic equipment titanium lamination layer hole making process optimization method.Based on the working condition of automatic equipment titanium lamination layer hole making, first, a finite element simulation model is established, and the working condition of titanium lamination layer hole making with different processing methods, tool parameters and cutting parameters is simulated.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, titanium lamination layer hole making special tool development test is carried out, the best tool parameters and cutting parameters are selected, and the special tool development is completed.After the development of special tool, tool wear test is carried out, and tool wear morphology and wear law are studied.Hole making quality optimization test is carried out, and the influence of tool parameters and cutting parameters on hole making quality is studied.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of aircraft assembly manufacturing, in particular to an automatic equipment titanium composite stack layer drilling process optimization method. BACKGROUND

[0002] Because carbon fiber composite materials have the characteristics of lightweight high strength, titanium alloy materials have the characteristics of high hardness and high temperature resistance, in the design stage of aircraft products, carbon fiber composite materials and titanium alloy materials are often widely selected. Therefore, in the process of aircraft product assembly, a large number of titanium composite stack layer drilling conditions will inevitably occur.

[0003] Carbon fiber composite materials are typical anisotropic materials, which are prone to defects such as tearing, delamination and burr during hole processing; titanium alloy has large cutting force and high cutting temperature during drilling, and is prone to phenomena such as chip winding and built-up edge. Carbon fiber composite materials and titanium alloy are typical difficult-to-machine materials.

[0004] For titanium composite stack layer drilling conditions, the traditional manual drilling method is generally used: workers use the traditional drilling-expanding-hinge process method to gradually complete the stack layer drilling. The above method has low drilling efficiency, requires more tools, has unstable drilling quality, and has high labor intensity. It is urgent to use a new process method with high efficiency and high precision to replace the drilling method.

[0005] In order to improve the efficiency of aircraft product assembly and realize the goal of digital and intelligent aircraft product assembly, a large number of automatic equipment are introduced into the aircraft assembly production line. Compared with traditional manual drilling, automatic equipment drilling has the advantages of high drilling efficiency, stable drilling quality and low labor intensity. However, the processing problem of titanium composite stack layer drilling still exists in the process of automatic equipment drilling. When traditional manual titanium composite stack layer drilling is used, the traditional drilling-expanding-hinge process method is often used, which requires more tools and takes a long time. In order to improve the processing efficiency, the automatic equipment is required to make a final hole with one tool, which puts higher requirements on the automatic drilling tool and process method.

[0006] At present, for the titanium composite stack layer drilling condition of the open area of the aircraft, automatic drilling equipment can be used to replace the traditional process method for drilling. Automatic equipment drilling usually makes a final hole with one tool, which has high processing efficiency. However, according to the on-site tool test, there are still problems such as delamination and splitting of the composite material, drilling precision out of tolerance, serious tool wear and low tool life.

[0007] Based on the above situation, before the automatic equipment titanium composite stack layer drilling, an automatic equipment titanium composite stack layer drilling process optimization method needs to be developed to optimize the drilling quality, improve the tool life and speed up the drilling efficiency. In order to improve the quality and efficiency of aircraft product assembly. SUMMARY

[0008] To solve the above technical problems, the application provides an automatic equipment titanium cladding layer hole making process optimization method.

[0009] The technical scheme of the application is as follows:

[0010] Based on the automatic equipment titanium cladding layer hole making condition, firstly, a finite element simulation model is established, and the titanium cladding layer hole making conditions of different machining modes, tool parameters and cutting parameters are simulated. According to the simulation results, the best machining mode is selected, and the influence law of cutting parameters and tool parameters on cutting force is studied. Based on the simulation results, titanium cladding layer hole making special tool development test is carried out, the best tool parameters and cutting parameters are selected, and the special tool development is completed. After the development of the special tool, the tool wear test is carried out, and the tool wear morphology and wear law are studied. The hole making quality optimization test is carried out, and the influence law of tool parameters and cutting parameters on hole making quality is studied.

[0011] An automatic equipment titanium cladding layer hole making process optimization method mainly comprises four main parts of 1, titanium cladding layer hole making simulation analysis, 2, titanium cladding layer hole making special tool development, 3, titanium cladding layer hole making tool wear law research, and 4, titanium cladding layer hole making quality optimization research.

[0012] 1, titanium cladding layer hole making simulation analysis comprises four links of 1-1, simulation model establishment, 1-2, different machining mode simulation analysis, 1-3, different tool parameter simulation analysis, and 1-4, different cutting parameter simulation analysis.

[0013] 1-1, the simulation model is established through the finite element simulation software Abaqus, and the material is set as carbon fiber and titanium alloy, wherein 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] Through the Abaqus script written by Python language, the total length, total width, total height and laying layer number of the composite material constitutive model are input, the constitutive model is automatically generated, and the cross section distribution 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 laying layer number 10. On the basis of the original, the titanium layer model is established by using the stretching function, and the corresponding cross section properties are distributed. Based on the global coordinate system, the fiber direction of the CFRP laminate material is created to realize the simulation of the anisotropy of the CFRP material. Each layer is defined orthogonally according to 0° / 90° direction.

[0015] Create the dynamic-display analysis step and set the analysis step time to 0.01. To shorten the calculation time and improve the calculation efficiency, the simulation is started with mass scaling and the mass scaling coefficient is set to 100. A small scaling coefficient will ensure the accuracy of the simulation results.

[0016] The material mesh is divided by selecting the hexahedral division method, eight-node linear hexahedral elements, reduced integration, hourglass control, and checking the element deletion. The tool mesh is divided by selecting the four-node linear tetrahedral element.

[0017] The simulation needs to run through the entire sheet metal model, so the definition of interaction needs to use the tool surface and the contact node. First, establish the contact method, set the tangential friction coefficient to 0.2, and the normal contact to hard contact. Select the nodes in the area with a larger contact range of the tool by selecting the ring, and create a node set. This method reduces the simulation calculation time and improves the simulation efficiency under the condition of completely defining the contact.

[0018] The tool displacement is realized by the amplitude. Since the total analysis step time is set to 0.01 in the above, the tool displacement is defined by the table amplitude. When the analysis time is 0.01, the tool displacement is linearly increased from 0 to the load defined value.

[0019] 1-2 Different machining methods simulation analysis mainly simulates three kinds of hole making methods: traditional drilling, spiral milling hole, and low-frequency vibration assisted hole making. First, compare the advantages and disadvantages of the three hole making methods: for the automatic equipment hole making process of aircraft parts, the advantages of traditional drilling hole making are high machining efficiency, drilling and tapping integrated hole making, strong equipment adaptability, and low processing cost. The disadvantages are low tool life and poor hole making quality. The advantages of spiral milling hole making are good hole making quality and high hole making life. The disadvantages are low machining efficiency, long time consumption, inability to tap work, high rigidity requirement for hole making equipment, and general versatility of automatic hole making equipment. The advantages of low-frequency vibration assisted hole making are good hole making quality and good titanium alloy chip breaking effect. The disadvantages are high price of low-frequency vibration assisted equipment, need for modification of existing equipment, poor adaptability of existing equipment, and high use cost.

[0020] To select the optimal machining method, the established titanium alloy stack simulation model is used to simulate the three machining methods with the same existing cutting parameters and tool parameters. After the simulation is completed, the axial force is analyzed.

[0021] 1-3 Different tool parameters simulation analysis After 1-2 different machining mode simulation analysis, the best machining mode has been selected, in order to simulate the hole drilling of titanium composite under different tool parameters, the three important parameters of drill point angle, clearance angle and helix angle are selected for analysis to study their main influence on the drilling of titanium composite. The simulation adopts the method of orthogonal test to generate multiple parameter combinations, and each parameter combination is simulated and analyzed respectively.

[0022] 1-4 Different cutting parameters simulation analysis After 1-3 different tool parameters simulation analysis, the best tool parameters have been selected, in order to simulate the hole drilling of titanium composite under different cutting parameters, the two important parameters of speed and feed rate are selected for analysis to study their main influence on the drilling of titanium composite. The simulation adopts the method of single factor test to generate multiple parameter combinations, and each parameter combination is simulated and analyzed respectively. After the simulation is completed, the axial drilling force, stress and cutting temperature of each parameter are compared to select the appropriate tool parameters.

[0023] 2, Development of special tool for drilling titanium composite After 1, simulation analysis of drilling titanium composite, in order to verify the simulation results, the development of special tool for drilling titanium composite is set up. 2, development of special tool for drilling titanium composite is mainly composed of 2-1 test condition preparation, 2-2 tool parameter optimization test, 2-3 cutting parameter optimization test.

[0024] 2-1 Test condition preparation: The workpiece materials selected for the test are carbon fiber composite material and titanium alloy laminated plate. Among them, the size of the composite material plate is 300x300mm, and the thickness is 8mm; the size of the titanium alloy plate is 300x300mm, and the thickness is 6mm. Combined with theoretical analysis and simulation results, the test tool is selected. The same manufacturer and the same batch of tools are used for laminated drilling test research to study the change law of drilling force and tool wear under different tool parameters. In the process of test research, in order to truly reflect the change between drilling force and tool wear under different tool parameters, the drilling force is measured when each hole is processed, and the tool wear is measured by measuring every five holes.

[0025] During the drilling process, the axial drilling force during the drilling process is detected in real time by the force measuring system, and the ultra-depth microscope is used to measure the tool wear of the tool.

[0026] 2-2 Tool parameter optimization test is set to select suitable tool parameters for drilling holes in titanium alloy composite. Single factor test method is adopted to drill holes in titanium alloy composite with different tool parameters including different drill point angle, clearance angle and helix angle. Axial drilling force is recorded during the test. The influence of tool parameters on axial drilling force is analyzed after the test to select the best tool parameters.

[0027] 2-3 Cutting parameter optimization test is set to select suitable cutting parameters for drilling holes in titanium alloy composite. After the best tool parameters are selected in 2-2 tool parameter optimization test, single factor test method is adopted to drill holes in titanium alloy composite with different cutting parameters. Axial drilling force is recorded during the test. The influence of cutting parameters on axial drilling force is analyzed after the test to select the best cutting parameters.

[0028] 3. Tool wear law research for drilling holes in titanium alloy composite is set to study the influence of cutting parameters on tool wear process and tool wear morphology during drilling holes in titanium alloy composite. Tool wear law research for drilling holes in titanium alloy composite consists of 3-1 tool wear and cutting parameter relationship research and 3-2 tool wear morphology research during drilling process.

[0029] 3-1 Tool wear and cutting parameter relationship research adopts single factor test method to drill holes in titanium alloy composite with different cutting parameters. Tool wear is photographed by using ultra-depth microscope every five holes during the test. Tool wear amount is recorded to analyze the influence of cutting parameters on tool wear. Tool wear morphology photographs taken by using ultra-depth microscope are used to compare and observe the change of tool outer edge corner wear after drilling the 10th, 20th, 30th and 40th holes to conduct 3-2 tool wear morphology research during drilling process.

[0030] 4. Drilling hole quality optimization research for titanium alloy composite is set to study the influence of tool parameters and cutting parameters on drilling hole quality, such as composite hole tear degree, titanium alloy hole exit burr height, surface roughness and drilling hole accuracy. Drilling hole quality optimization research for titanium alloy composite consists of 4-1 drilling hole quality and tool parameter relationship research and 4-2 drilling hole quality and cutting parameter relationship research.

[0031] 4-1 Drilling hole quality and tool parameter relationship research adopts single factor test method to drill holes in titanium alloy composite with different tool parameters. Ultra-depth microscope is used to observe the composite hole tear degree under different tool parameters. Micrometer is used to measure the titanium alloy hole exit burr height and hole diameter accuracy under different tool parameters. Roughness measuring instrument is used to measure the hole wall roughness under different tool parameters.

[0032] 4-2 Research on the relationship between hole quality and cutting parameters The method of single factor test is used to carry out titanium alloy laminated drilling test by using different cutting parameters, the ultra-depth microscope is used to observe the degree of hole wall tearing of the composite material under different cutting parameters, the micrometer is used to measure the height of the titanium alloy hole exit burr under different cutting parameters, and the hole diameter accuracy, and the roughness measuring instrument is used to measure the hole wall roughness under different cutting parameters.

[0033] The beneficial effects brought by the application are:

[0034] 1. By the process optimization method, the tool parameters and cutting parameters of the automatic equipment titanium alloy laminated hole drilling are improved, the hole quality is optimized, the tool life is improved, and the hole drilling efficiency is improved. The assembly quality and efficiency of the aircraft product are improved.

[0035] 2. The process method provides experience and guidance for subsequent related hole drilling process optimization. DETAILED DESCRIPTION

[0036] As Figure 1 shown is a drilling force measurement system schematic diagram for test;

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

[0038] The specific embodiment and steps of the application are as follows:

[0039] 1. Use the special tool for titanium alloy laminated hole drilling developed, start the automatic equipment titanium alloy laminated hole drilling test;

[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 new and intact;

[0041] 3. Prepare the test plate for the test, and fix the test plate firmly;

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

[0043] 5. According to the test plate and the tool state, carry out the equipment offline programming work, and input the suitable cutting parameters obtained by test.

[0044] 6. After checking that all aspects are correct, start the automatic hole drilling equipment, and start the test. During the test, the process personnel need to observe the drilling situation, and stop the test in time if there is an abnormality.

[0045] 7. After the test, check the tool condition and hole quality.

[0046] Finally, the present application is not limited to the above description, but can encompass any modification falling within the scope defined by the specification.

Claims

1. An optimized method for drilling holes in automated titanium-coated laminates, characterized in that, The steps are as follows: Step 1: Simulation analysis of hole fabrication in titanium composite stacks; Step 2: Development of specialized cutting tools for drilling in titanium-coated laminates; Step 3: Study on the wear pattern of drilling tools for titanium-coated laminated holes; Step 4: Research on optimization of hole formation quality in titanium composite laminates; The first step of the simulation analysis for drilling holes in the titanium laminate includes four stages: 1-1 establishing a simulation model; 1-2 simulation analysis of different processing methods; 1-3 simulation analysis of different tool parameters; and 1-4 simulation analysis of different cutting parameters. 1-1 The simulation model was established using the finite element simulation software Abaqus. The materials were set as carbon fiber and titanium alloy. The damage model of T800 material was defined by the user, and the damage model of titanium alloy material used the Johnson-Cook damage model. Using an Abaqus script written in Python, this system automatically generates a constitutive model of a composite material and assigns cross-sectional properties to each layer by inputting the total length, width, height, and number of CFRP layers. The input parameters are: overall dimensions: 30mm length, 30mm width, 8mm CFRP layer thickness, and 10 layers. Based on the existing model, a titanium layer model is created using the stretching function, and corresponding cross-sectional properties are assigned. A global coordinate system is used to create the fiber orientation of the CFRP laminate material, achieving anisotropy simulation of the CFRP material. Each layer is orthogonally defined at 0° / 90°. Create a dynamic-display analysis step and set the analysis step time to 0.

01. To shorten the calculation time and improve the calculation efficiency, enable 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. The material mesh is generated using a hexahedral meshing method with eight-node linear hexahedral elements, reduced integration, hourglass control, and element deletion is selected to generate the sample mesh. The tool mesh is generated using four-node linear tetrahedral elements. The simulation needs to cover the entire sheet metal model, therefore the interaction needs to be defined using the interaction between the tool surface and the contact nodes; first, establish the contact mode, set the tangential friction coefficient to 0.2, and the normal contact to hard contact; use the collar selection to select the nodes in the area with a large tool contact range, and create a node set; the tool displacement is achieved by the amplitude; 1-2 Simulation Analysis of Different Machining Methods: Simulation analysis is performed on three hole-making methods: traditional drilling, spiral milling, and low-frequency vibration-assisted hole making. Using the established simulation model of titanium composite, and employing the same existing cutting parameters and tool parameters, simulations were performed on the three machining methods mentioned above. After the simulations were completed, the axial forces were analyzed. The simulation analysis of different tool parameters in section 1-3 was conducted after the simulation analysis of different machining methods in section 1-2, i.e., after the optimal machining method was selected. This was to simulate the drilling conditions of titanium laminates under different tool parameters. Three important parameters, namely drill tip angle, clearance angle, and helix angle, were selected for analysis to study their main influence on the drilling of laminated materials. The simulation adopted the orthogonal experimental method to generate multiple sets of parameter combinations, and simulation analysis was performed on each set of parameter combinations separately. The simulation analysis of different cutting parameters in sections 1-4 is set up after the simulation analysis of different tool parameters in section 1-3, i.e., after the optimal tool parameters have been selected, in order to simulate the hole-making process of titanium-coated laminates under different cutting parameters; the two important parameters of spindle speed and feed rate are selected for analysis.

2. The method for optimizing the drilling process of titanium-coated laminates in automated equipment as described in claim 1, characterized in that, The second step of the development of a special tool for drilling holes in titanium-coated laminates includes 2-1 preparation of experimental conditions, 2-2 tool parameter optimization test, and 2-3 cutting parameter optimization test. 2-1 Experimental Conditions Preparation: The workpiece materials selected for the experiment were carbon fiber composite material and titanium alloy laminated plate; the composite material plate was 300×300mm in size and 8mm thick; the titanium alloy plate was 300×300mm in size and 6mm thick; the cutting tools for the experiment were selected based on theoretical analysis and simulation results. 2-2 Tool parameter optimization test was set up to select suitable tool parameters for drilling titanium-coated laminates. The test adopted a single-factor test method, and drill bits with different point angles, clearance angles, and helix angles were used to conduct drilling tests on titanium-coated laminates. The axial drilling force under different tool parameters was recorded during the test. After the test, the influence of tool parameters on axial drilling force was analyzed to select the optimal tool parameters. The 2-3 cutting parameter optimization test was designed to select suitable cutting parameters for drilling holes in titanium-coated laminates. After selecting the optimal tool parameters in the 2-2 tool parameter optimization test, a tool with those parameters was selected, and a single-factor test method was adopted to conduct drilling tests in titanium-coated laminates with different cutting parameters. During the test, the axial drilling force of different cutting parameters was recorded, and the influence of cutting parameters on axial drilling force was analyzed after the test to select the optimal cutting parameters.

3. The method for optimizing the drilling process of titanium-coated laminates in automated equipment as described in claim 1 or 2, characterized in that, The study on the wear law of the tool for drilling holes in the third step of titanium composite stacking includes 3-1 study on the relationship between tool wear and cutting parameters, and 3-2 study on the tool wear morphology during the drilling process. 3-1 Study on the relationship between tool wear and cutting parameters: A single-factor experiment was conducted, and different cutting parameters were selected for titanium laminated hole drilling experiments. During the experiment, the cutting edge wear was photographed with an ultra-depth-of-field microscope after drilling 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 photographs taken with the ultra-depth-of-field microscope, the changes in the wear of the tool's outer edge corner after drilling the 10th, 20th, 30th, and 40th holes were compared and observed, and the tool wear morphology during the drilling process was studied in 3-2.

4. The method for optimizing the drilling process of titanium-coated laminates in automated equipment as described in claim 1 or 2, characterized in that, The fourth step of the study on the optimization of hole-making quality of titanium composite stacks includes 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; 4-1 Study on the Relationship between Hole Quality and Tool Parameters: A single-factor experimental method was used to conduct titanium composite drilling tests with tools of different parameters. An ultra-depth-of-field microscope was used to observe the degree of tearing around the composite hole under different tool parameters. A dial indicator was used to measure the burr height at the exit of the titanium alloy hole and the hole diameter 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: Single-factor experimental method was used to conduct titanium composite drilling tests with different cutting parameters. Ultra-depth-of-field microscope was used to observe the degree of tearing around the hole of the composite material under different cutting parameters. Dial indicator was used to measure the burr height and hole diameter accuracy of titanium alloy hole exit under different cutting parameters. Roughness measuring instrument was used to measure the hole wall roughness under different cutting parameters.

5. The method for optimizing the drilling process of titanium-coated laminates in automated equipment as described in claim 3, characterized in that, The fourth step of the study on the optimization of hole-making quality of titanium composite stacks includes 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; 4-1 Study on the Relationship between Hole Quality and Tool Parameters: A single-factor experimental method was used to conduct titanium composite drilling tests with tools of different parameters. An ultra-depth-of-field microscope was used to observe the degree of tearing around the composite hole under different tool parameters. A dial indicator was used to measure the burr height at the exit of the titanium alloy hole and the hole diameter 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: Single-factor experimental method was used to conduct titanium composite drilling tests with different cutting parameters. Ultra-depth-of-field microscope was used to observe the degree of tearing around the hole of the composite material under different cutting parameters. Dial indicator was used to measure the burr height and hole diameter accuracy of titanium alloy hole exit under different cutting parameters. Roughness measuring instrument was used to measure the hole wall roughness under different cutting parameters.

6. The method for optimizing the drilling process of titanium-coated laminates in automated equipment as described in claim 2, characterized in that, In the preparation of the test conditions described in 2-1, stacked drilling tests were conducted using tools from the same manufacturer and the same batch to study the variation of drilling force and tool wear under different tool parameters. During the test, in order to accurately reflect the variation of drilling force and tool wear under different tool parameters, the drilling force was measured when machining each hole. The study of tool wear was conducted by measuring once every five holes machined.

7. The method for optimizing the drilling process of titanium-coated laminates in automated equipment as described in claim 6, characterized in that, During the drilling process, the axial drilling force is monitored in real time by a force measuring system, and the tool wear is measured using an ultra-depth-of-field microscope.

8. The method for optimizing the drilling process of titanium-coated laminates in automated equipment as described in claim 1, characterized in that, In steps 1-4, the simulation adopts a single-factor experiment method to generate multiple sets of parameter combinations. For each set of parameter combinations, simulation analysis is performed separately. After the simulation is completed, the axial drilling force, stress, cutting temperature and other factors of each set of parameters are compared to select the tool parameters.

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