With the third development of manufacturing industry in China, the requirement of manufacturing technology for advanced equipments increases rapidly. Carrying out research on the manufacturing technology is an effective way to improve the cold and hot working in China. This paper presents the research progress on cutting technology, forming technology and additive manufacturing in Xi'an Jiaotong University in recent years. Some achievements are well suitable for the manufacturing of airplane parts. Other research work in frontier manufacturing, such as bio-fabrication and micro/nano fabrication, are finally reviewed.
The traditional reliability analysis has such shortcomings that it relies on probability statistics with the large sample statistical data. This study proposes two operation reliability assessment methods which use running condition monitoring information to realize the reliability evaluation under small sample. They are the reliability evaluation methods based on the normalized wavelet information entropy and the damage quantitative identification respectively. Vibration signals of mechanical equipment are decomposed and reconstructed by means of second generation wavelet package to acquire decomposed signals in sub-frequency bands, so that full condition information of running equipment can be adequately used. We take relative energy in each sub-frequency band to calculate normalized information entropy. The reliability degree, an important reliability index, is transformed by using the normalized wavelet information entropy to assess operation reliability for running equipment. A new operation reliability assessment index called membership reliability degree is defined and an operation reliability assessment model is built based on quantitative damage diagnosis. Successful applications have been achieved to assess operation reliability of an oxy-generator compressor and the wheel bearings in electric locomotives, which demonstrated that the proposed approaches are reasonable and effective. The paper provides new approaches without large sample size, which are independent of probability to operation reliability assessment for large machinery.
Three types of nano-scale structure have been fabricated and characterized using SEM, AFM, etc. In this paper, multilayer thin film deposition technique has been used to fabricate nano-scale structure with 20nm, 25 nm and 35 nm line-width. LER and LWR of nanoline are evaluated with an offline image analysis algorithm. The experimental results indicate that the LER/LWR of the lines is low and the uniform of the lines is high. EBL and ICP technique are employed to fabricate grating patterns with nominal height 220 nm. The result shows that the high frequency fluctuations of line edges after etching decrease, the correlation length increases and values of root mean square deviation (σ) increase. Single and multiple nano steps have been fabricated using FIB technique, and the relationship between the size of the Z-axis and energy of process are analyzed.
In this paper, the research achievements about water lubricated hybrid bearing are summarized in order to make the bearing be of higher stiffness, higher precision and higher stability. The key technology and critical factors which affect the performance of water lubricated hybrid bearing as well as the recent main achievement and development at home and abroad are commented and analyzed from the aspects of bearing structure, thermal deformation and so on. At last, the research trend of water lubricated hybrid bearing for high speed spindle is predicted and prospected.
Based on how to improve the inherent thermal performance of high speed high precision machine tools, theories and methods about thermal characteristic analysis, thermal structure optimization and cooling technology were introduced systematically in this paper. In order to provide reference for machine tools researchers and designers, the latest progress and technology on thermal design of machine tools were reviewed and research emphasis and directions were also discussed.
The "system engine + function component" architecture for the reconfigurable monitoring and diagnostic system is presented. And three types of embedded monitoring units (vibration, power and acoustic emission) are designed for four function parts of machine tool, which can greatly improve the real-time and flexibility of the bottom monitoring information acquisition. This paper has also developed a series of regular monitoring and diagnostic components for computer numerical control (CNC), and some special components for special requirements of these machines. Then the monitoring and diagnostic system for specific machine tools, which has been running in the Qinchuan Grinding Machine Co. Ltd. and Dalian Machine Tool Group Co., can be realized by conveniently packaging and loading of these function components.
The high-accuracy measurement of complex airfoil surfaces is a critical issue in the inspection of blades. Aiming at this problem, a compound measuring principle is proposed in this paper. Using the principle, the airfoil surface and root datum of a blade are measured based on contact inductance method and non-contact laser triangular method, respectively. And a four-coordinate measuring system is designed and established. Then, on the basis of the mechanical structure of the measuring system, the geometric error of which is analyzed syste-matically. And a corresponding extraction and compensation method is proposed based on the laser interferometry. The experimental results show that the proposed error analysis and compensation methods can improve the accuracy of the four-coordinate measuring system effectively.
The concept of biofabrication was provided by School of Mechanical Engineering, Xi'an Jiaotong University since the 1990s. Using the engineering methods to solve the medical issues, we have made some achievements and development on the implants for bone and cartilage, liver, intestinal tissue as well as brain. This paper emphasized on the lastest research work of the customized artificial prosthesis, bioactive bone and joint, and tissue engineered liver in our laboratory, which was corporated with the experts and sciencists of various areas from medicine, biology as well as materials for more than 20 years. Furthermore, it also explored the problems and prospects for the development and application of biofabrication.
Many large-scale (several meters to dozens of meters) or complex parts and new composite materials are used in atuo, aerospace, shipping, military industry and so on, the rapid and feasible 3D profile, deformation and strain measurement are in urgent need. In view of the need, a new approach based on close range photogrammetry and digital image correlation is proposed and implemented. In this method, multi-image in 2D sequence are taken by many kinds of industrial cameras, and the 3D coordinates, deformation and strain data of tested objects can be resolved quickly based on these images. Owing to this method, not only rapid measurement on large-scale or complex parts, small to medium parts, micro-nano scale and material property analysis can be realized, but also vabration and shock from low to high velocity and modal analysis can be satisfied. Application results in mechanical engineering, materails science, mechanics and many industries show that, the new method is versatile, rapid, feasible and flexible. Futhermore, remarkable economic and social benefits have been achieved.
Based on biological detection and molecular diagnostics technology development, the author summarized high-end equipment independent research in medical diagnostics, disease control, food safety, quarantine inspection, biology and medical research field of molecular diagnostics. The paper focused on research and development of key technology and instrumentation engineering technology, detection performance verification and successful application in the field of social development priorities of the real-time fluorescence quantitative polymerase chain reaction (PCR) nucleic acid detector, diagnosis of high-end equipment, the development and application and subsequent automatic nucleic acid directional monitoring with high-resolution analysis equipment development of handheld adenosine triphosphate (ATP) bioluminescence rapid detection of bacteria.
In this paper, the servo motor driven swaging machine was designed; profile of striker was derived from cycloidal motion curve and its motion features were analyzed. The maximum load of swaging machine was calculated by upper bound method. According to the calculation, the maximum load of swaging machine decreased with die angle increasing, but on the other hand, the push force on perform increased. The compromised die angle in the field was 5°~ 15°.
This article introduces the key techniques of electric vehicle from the aspects of driving motor, battery, battery management system, motor control and energy recovery system. The development of the key techniques in electric vehicle is presented. With the support of our government, electric vehicle will be used widely in the future along with the development of the key techniques on motor, battery and control system.
To solve the path planning problem of mobile robots in complicated environments, combining the small computational amount of artificial potential field and the adaptive regulation ability of artificial immune network, an improved immunity path planning algorithm is presented. To further improve the search ability and convergence of immune network, the planning results of artificial potential field are taken as the prior knowledge to construct the guidance weight, and the antibody instruction definition and distance changes after the antibody transition are taken as the variables to construct the antibody transmission probability operator. Compared with the correlative planning algorithms, simulation results indicate that the optimal planning ability and network convergence of proposed algorithm is highly improved.
As the power equipment is complex electromechanical system with the typical features of wide application range, continuous operation and multiple influence factor, there are some issues such as the lacking of monitoring and diagnosing technology, the low intelligence level and insufficient of service provided. To solve these problems, monitoring and service support system is researched and developed. System platform is constructed to meet the requirement of monitoring, performance optimization and maintenance service in life cycle of power equipment. Subsequently, the key techniques, such as signal collection, dynamically adaptive monitoring, health condition assessment, intelligent diagnosis, rapid balancing of rigid rotor and intelligent maintenance decision, are researched. Finally, demonstration base of monitoring and service support is to be built to provide analysis of monitoring and diagnosis and management of equipment maintenance in user enterprises.
To solve the problem of online automatic balance control of machine tool spindle, the balancing methods and the automatic balancing technologies were discussed in this paper, and then an online automatic balance mechanism based on hydrojet-typed mass compensation principle was proposed. The feasibility of this balancing device was verified on a motorized spindle, and the empirical results validated the effectiveness of this mechanism.
The performance of computerized numerical control (CNC) machine tool is evaluated by the traditional positioning error and the positioning repeatability, which is in quasi static and cannot reflect the precision of machine tool in the process of movement and machining. In this paper, a novel precision evaluation method which takes the dynamic precision as index is proposed for high-speed machine tool. The precision of machine tool is described through the consistence of the actual trajectory and the ideal command. The specific evaluation index of dynamic precision is provided. Meanwhile, the measure method of evaluation index is put forward. It can be obtained that this new evaluation method of machine tool precision can evaluate the quality of key performance in CNC machine tool systematically and roundly.
In order to suit for the special requirements of the oil and gas fields, in this paper, the design and fabrication of a high-temperature and high-pressure sensor chip was described. And the related high-performance digital transmitter system was produced. The textual sensor chip was designed to accomplish the thermostability in the high temperature environment which the traditional sensor can't suit for. The linearity and accuracy of the system were promoted by the digital compensation technology. And the associated equipment were integrated into the system. Moreover, in order to meet the requirements of the oil and gas fields inspect managements, the wireless sensor network were designed, which can guarantee the high-efficiency operation and control of the industrial production. Through the experiments, the high-accuracy and reliable of the high-performance micro sensor and digital transmitter system were credible. The accuracy of it is above 0.2 % FS. The system has reached the world class and was especially significant for the domestic petrochemical industry.
In this paper, recent researches about basic theory and applications of EFEM are reviewed, which indicate that the development direction of this method tend to predict the dynamic response of complex structures under the complex environments. Then, towarding to this tendency, the achievements of our research group are presented, which focus on predict the dynamical response of actual complex mechanical structures excited by complex external excitation in practical. There are three main aspects are referred: the first section is that the EFEM to predict the response of complex structures is developed by us when the power flow transfer of multi-waves considered, such as the cylindrical shell and truncated conical shell, and this method help us to obtain the local detail response of complex structures in mid and high frequency range; the second part is that we extend the EFEM to predict the vibro-acoustical characteristics of complex structures under the complex excitations, including the fluctuate pressure load and the acoustic load in reverberation chamber; the last section is that we develop the EFEM solver and the application platform, which facilitate the further practical applications of EFEM greatly. At the end of this paper, the problems to be solved and feasible research contents in the future of EFEM are pointed out briefly.