With the rapid development of aviation industry, the market share of large-scale, integral, precision and high-performance die forgings in aviation key components is expanding. The increasing size, complexity and material strength of aviation key components have brought great challenges to the overall die forging of large aviation key components. Firstly, the critical challenges and solutions of realizing the integral die forging of large aviation key components were introduced in this paper. Then, the research progress of integral precision die forging technology in typical large aviation key components such as aircraft bulkhead, landing gear and engine turbine disk was discussed. Finally, the future development of integral die forging technology of large aviation key components was prospected.
To solve the problems of poor integration of business systems, opaque assembly process, and untimely exceptions handling, an aircraft assembly line digital twin system for layered and transparent supervisory control is proposed. After the requirements analysis, a four-tier architecture is proposed, namely physical layer, twin data layer, twin model layer and application layer. And three core functional modules are designed and implemented, including twin database construction for multi-dimensional data integration, final assembly lines digital twin modeling for transparency and visualization, integrated hierarchical supervisory control for on-site exception handling. The practical application shows that proposed system meets the requirements of multi-level, multi-dimensional, multi-role distribution remote supervisory control and comprehensive analysis, and effectively improves the digital and transparent level of aircraft final assembly.
316L austenitic stainless steel is widely used in aerospace because of its excellent mechanical properties and corrosion resistance. However, work hardening and harsh tool-chip contact environments lead to decreased tool life and machining efficiency. In this paper, finite element simulation and cutting experiments of restricted contact cutting were constructed to explore the effect of restricted contact tools on the force and thermal characteristics of the machining process. The effect of cutting and restricted contact parameters was investigated through the establishment of the finite element simulation model of restricted contact cutting, and the action mechanism of variable restricted contact structure was clarified. It indicated that the variable-length restricted contact structure can effectively reduce the cutting force and temperature and improve the cutting performance, among which the trapezoidal restricted contact structure has the best effect on improving cutting performance. The result, which was validated by cutting experiments and proved the reliability of the finite element simulation, offers the basis for optimizing the structure of the restricted contact tool.
CNC machining simulation is the centralized embodiment of digitalization and intelligence in the development of manufacturing industry. But the existing research still has deficiencies in accuracy in the calculation of position and attitude of machine tool movement. Constraints such as command mode, acceleration and deceleration control of CNC system and geometric error of machine tool are not considered. For this issue, this paper studies the motion of five-axis machine tool simulation algorithm. Firstly, the topology, model and coordinate system of fiveaxis CNC machine tool are completely defined. Secondly, the topology structure, model and coordinate system of five-axis CNC machine tool are defined completely. On this basis, the densification of simulation of tool position and attitude based on command mode of CNC system and the corresponding time marking calculation method are explored. Combining with geometric error model of five-axis CNC machine tool, the simulation position and attitude of the model movement process of the machine tool which is more in accordance with the actual geometric state of the machine tool are obtained. The proposed algorithm is validated by topological structure modeling, tool position simulation densification and position and attitude calculation of machine tool model considering geometric errors, which proves the feasibility and validity of the algorithm.
Robotic belt grinding has higher cutting efficiency and surface quality. However, implicit local contact status makes it is difficult to guarantee processing accuracy and hinders its application in high-end industries, especially when the workpiece has complex contour. And the current local contact status computing methods are inefficient and cannot meet timeliness requirements. Therefore, after analyzing results of FEM and BEM in computing the local contact status, this paper acquires the contact width on abrasive belt based on machine vision. Then the contact width is used as the boundary condition of BEM. Finally, this paper has achieved the contact status fast calculation of the point cloud within 18 mm×18 mm area with the accuracy of 0.2 mm and in 1 s. Compared with FEM calculation results, the maximum error of the contact status obtained by the novel method is no more than 5.6%.
In this paper, the experiments on grinding of particle-reinforced titanium matrix composite (PTMCs) were conducted using single-layer brazed CBN wheels. The comparative grinding performance was studied in terms of grinding force and grinding temperature by grinding of PTMCs and TC4 titanium alloy. The evolution process of PTMCs material removal was discussed by the finite element method. The results show that the grinding forces for PTMCs are always 15%–30% higher than that for TC4. The grinding temperature for PTMCs is always 7%–11% higher than that for TC4. PTMCs is more difficult to machine than TC4 titanium alloy. The material removal process of PTMCs includes the ductile removal of TC4 matrix material and the brittle removal of TiC reinforced particles. The hole defect on the grinding surface is created by the brittle removal. When the grinding speed decreases from 120 m/s to 20 m/s, the depth of the hole defect on the ground surface increases from 0.8 μm to 3.5 μm, an increase of about 3.4 times. The influence of reinforced particle brittle removal on PTMCs ground surface hole defects can be reduced by increasing the grinding speed.
Based on the idea of nonlocal theory, peridynamics describes the movement of material particles by solving spatial integral equations. It is suitable for describing the crack growth and fracture behavior of workpiece materials during severe plastic deformation in cutting process. In this paper, the elastoplastic constitutive model of Ti2AlNb is constructed based on ordinary state-based peridynamics, and material failure and contact criteria are developed. By solving discrete basic motion equations, a state-based peridynamics numerical model is established to study the cutting process of Ti2AlNb alloy. Then the chip formation process for orthogonal cutting of Ti2AlNb is simulated and analyzed. The results demonstrate that the peridynamics method can accurately simulate the material deformation and damage evolution during machining of Ti2AlNb. The error between the predicted chip shear angle of 40.23° and the experimental result of 38.89° is 3.45%. The full width at half maximum of the damage spatial distribution is defined as the width of the primary shear zone, and the predicted value is 0.06 mm with an error of less than 7%.
The path planning of automated guided vehicles (AGV) is an important research topic in the field of industrial production and logistics. Collision-free path planning of multiple AGVs is a difficult problem in research. In this paper, based on the actual industrial production site, the traditional A* algorithm is improved by using the Chebyshev distance, which significantly reduces the search time and the number of search nodes of the A* algorithm, and improves the path search efficiency at the same time. The improved A* algorithm combined with the time window algorithm is used to solve this problem. Pre-judge the node occupancy on multiple AGV paths through the time window model, and dynamically adjust the AGV priority according to the production task requirements and the distance of the AGV from the end point. This algorithm effectively solves the deadlock and collision problems caused by multiple AGVs driving at the same time. The experimental results show that when the algorithm is used for dynamic path planning of multiple AGVs, the path search efficiency is significantly improved and the path conflict problem is effectively resolved.
The superplastic behavior of TA32 titanium alloy sheet was investigated by constant strain rate tensile tests at deformation temperature range of 920–980 ℃ and strain rate range of 5×10–5–1×10–3 s–1. The deformation characteristics and microstructure evolution during superplastic bulging of cone shaped part was analyzed. The results show that TA32 alloy provides superior superplastic deformation capability, with a maximum elongation up to 864% at 920 ℃ with the strain rate of 1×10–3 s–1. The height of the cones is higher at 940 ℃ and 960 ℃ , 90 mm and 92 mm, respectively, and microstructure has no significant change with different deformation.
Studied the numerical simulation calculation of laser shock peening of the tooth root of high-strength aerospace gears, the numerical calculation method of laser shock peening pressure was proposed, and the finite element model of laser shock peening of single tooth of aviation gear considering the angle of laser incidence was established. The average value of the residual stress in the width direction at the tooth root was –603.97 MPa calculated by simulation, which was 0.15% different from the average value of the residual stress in the width direction at the tooth root of the gear measured by experiments. Systematic studies were further conducted to investigate the effects of key parameters such as the laser pulse energy, overlap rate and spot radius on the residual stress at the surface and subsurface of the gear tooth root region. The result shows that the average residual compressive stress in the tooth width direction is greater than that in the tooth profile direction at the same depth layer. Increasing the laser pulse energy or the overlap rate can increase the average surface layer residual compressive stress, however, increasing the laser spot radius will reduce the surface layer residual compressive stress average. Increasing the laser overlap rate can effectively reduce the stress fluctuations in the residual stress distribution on the surface, however, an excessively high overlap rate will greatly reduce the efficiency of the laser shock peening process and the actual overlap rate should not exceed 0.8.
TA18 alloy was chosen as the experimental material. The samples were subjected to thermal oxidation treatment in a conventional muffle furnace under air atmosphere. The effect of thermal oxidation temperature on the microstructure and performance was studied. The microstructure, phase constituents, hardness, corrosion and wear resistance were evaluated by optical microscope (OM), XRD, micro-hardness tester, immersion test in 36%–38% (mass fraction) HCl solution, friction and wear tester. The results showed that the oxidized film was consisted of oxide layer and oxygen diffusion zone beneath, with rutile TiO2 as the predominant phases along with a small amount of Al2O3, and the amount of rutile increased with the increase of oxidation temperature. The results also showed that the surface hardness increased with the increase of oxidation temperature of 500–800 ℃ , while decreased beyond 800 ℃. The corrosion and wear resistance was obviously improved after thermal oxidation, and 800 ℃ was the optimal temperature to improve the corrosion resistance in 36%–38% (mass fraction) HCl solution, and 700 ℃ was the optimal temperature to improve the wear resistance.
One of the important application directions of airborne laser weapon is to interference and damage the incoming surface-to-air and air-to-air missiles, in order to realize the self-defense of the carrier. The development process, technical characteristics and operational capability of the abroad surface-to-air and air-to-air missiles are briefly summarized, combined with the mechanism under laser irradiation, the characteristics of laser weapon’s interference and damage to missiles are expounded. On this basis, the feasible path, capability boundary and operation mode of selfdefense laser weapon for airborne platform are analyzed and researched. The development status and trend of airborne laser weapons are briefly described, and development route and capability level of the key technologies involved are analyzed and evaluated. At last, the analysis and prediction of the future of airborne self-defense laser weapons are proposed.
