Machining process model based on virtual reality environment

Virtual manufacturing is fast becoming an affordable technology with wide-ranging applications in mod ern manufacturing. Its advantages over existing technology are primarily that users can visualize, feel involvement and interact with virtual representations of real world activities in real time. In this paper, a virtual cutting system isbuilt which can simulate turning process, estimate tool wear and cutting force using artificial neural network etc. Using the simulated machining environment in virtual reality (VR), the user can practise and preview the operations for possible problems that might occur during implementation. This approach enables designers to evaluate and design feasible machining processes in a consistent manner as early as possible during the development process.     

Investigations and practices on green manufacturing in machining systems

A machining system is a typical manufacturing system. A green manufacturing function framework of machining systems is structured to describe the traits of input, output and control elements in the system. Based on the function framework, the green manufacturing problem framework of machining systems is presented. The green manufacturing problems in machining systems are classified into three classes and related series of subclass problems. The three classes of problems in the green manufacturing problem framework are the problems of the minimization of resource consumption, the minimization of environmental discharge, and the synthesized minimization of both of them. A series of investigations and practices on green manufacturing in machining system, performed by the authors for quite a long period, are introduced in brief, such as the optimizing system for raw material cutting, the matching system for energy-saving in machining, the design of highly efficient dry hobbing machine tools, the multi-objective decision-making model for green manufacturing in machining systems, and the decision-making supporting system for green manufacturing in machining processes. Foundation item: Project (50475062) supported by the National Natural Science Foundation of China; project (47-19) supported by the Natural Science Foundation of Chongqing, China     

Prediction of diameter errors compensation in bars turning

On the basis of analyzing the machine-workpiece-tool system, the main factors affecting diameter errors in bars turning are considered, and the mathematic models of the actual workpiece diameter at the cutting point are established according to the three usual methods of mounting workpieces on a turning machine. Further a prediction system for diameter errors is developed; a new method, called discrete nodes output, is presented and applied to expressing workpiece diameter errors at given points along the part axis, then off-line compensation is implemented according to the prediction values to diminish machining errors. The results indicate that the method can diminish diameter errors more than 70%, greatly improve the machining accuracy of bars. Foundation item: Projects (50175081 and 50475117) supported by the National Natural Science Foundation of China; project (033181611) supported by the Tianjin Municipal Science and Technology Commission     

Remanufacturing system based on totally automatic MIG surfacing via robot

Remanufacturing system is a term of green system project which conforms to the national sustainable development strategy. With the demand of the high adaptability of the varieties of waste machining parts, the short product cycle, the low machining cost and the high product quality are offered. Each step of the remanufacturing system from the beginning of the scanning to the accomplishment of the welding was investigted. Aiming at building a remanufacturing system based on totally automatic MIG surfacing via robot, advanced information technology, remanufacturing technology and management, through the control of the pretreatment and the optimization to minimize the time of remanufacturing and realize the remanufacturing on the terminal products of varieties, were applied. The steps mainly incude: 1) using the visual sensor which is installed at the end of the Robot to rapidly get the outline data of the machining part and the pretreatment of the data; 2) rebuilding the curved surface based on the outline data and the integrated CAD material object model; 3) building the remanufacturing model based on the CAD material object model and projecting the remanufacturing process; and 4) accomplishing the remanufacture of the machining part by the technology of MIG surfacing. Foundation item: Projects(50075086; 50235030) supported by the National Natural Science Foundation of China; Project(413270103) supported by the National Basic Research Foundation of China; Project(2000-476) supported by the Ministry of Education for the Outstanding Teachers     

Key technologies in whole lifecycle of electromechanical products: state of art

Nowadays, issues on population, environment and resource have become the world’s attentive focus. Sustainable development has been widely accepted around the world. As one of the biggest waste generator and resources consumer, manufacturing industry is facing more challenges as well as opportunities. In order to reduce both resource consuming and waste discharging effectively, traditionally manufacturing mode should be improved. Newly emerged creative technologies and strategies, including green design, green manufacturing and cleaner production, are regarded as the radical resolvent for current environment and resource issues and they will be the only way in the future that manufacturing will evolve. In this paper, a serial of research on green design/manufacturing and cleaner product theoretically and practically was presented. These creative technology and strategy will give strong support to ‘green’ the whole electromechanical designing and manufacturing processes. Foundation item: Project (2002AA421240, 2004AA420120) supported by the National High Technology Research and Development Program of China; project (50445003) the supported by National Natural Science Foundation of China     

Modeling and simulation of crushing process of spiral mining head

1 INTRODUCTIONThe research of mining deep seabed cobalt-richcrust is a hotspot of international oceanology[1].Based on the mining manganese nodule ,lots of re-searches on mining cobalt crust have been madedeeply and many kinds of methods ,such as thei m-proved CLB, mining vehicle +lifting system +surface supporting ship have been put forward.Mining vehicle consists of collecting machine ,tracked treading machine and spiral mininghead[2 ,3].The first step of mining cobalt crust is tocrush…     

Phase composition, transition and structure stability of functionally graded cemented carbide with dual phase structure

The phase composition, phase transition and phase structure transformation of the wire-cut section of functionally graded WC-Co cemented carbide with dual phase structure were investigated by XRD phase analysis. It is shown that the composition of η phase in the core zone is Co3W3C （M6C type）. The structure of cobalt based solid solution binder phase is fcc type. At the cooling stage of the sintering process, the phase transition of η phase, i.e. M6C→M12C and the martensitic phase transition of the cobalt based solid solution binder phase, i.e. fcc→hcp are suppressed, which facilitates the strengthening of the alloy. Because the instantaneous temperature of the discharge channel is as high as 10 000 ℃ during the wire cutting process, the processed surface is oxidized. Nevertheless, the oxide layer thickness is in micro grade. In the oxide film, η phase is decomposed into W2C and CoO, and cobalt based solid solution binder is selectively oxidized, while WC remains stable due to the existence of carbon containing liquid organic cutting medium.     

A bi-objective model for job-shop scheduling problem to minimize both energy consumption and makespan

The issue of reducing energy consumption for the job-shop scheduling problem in machining systems is addressed, whose dual objectives are to minimize both the energy consumption and the makespan. First, the biobjective model for the job-shop scheduling problem is proposed. The objective function value of the model represents synthesized optimization of energy consumption and makespan. Then, a heuristic algorithm is developed to locate the optimal or near optimal solutions of the model based on the Tabu search mechanism. Finally, the experimental case is presented to demonstrate the effectiveness of the proposed model and the algorithm. Foundation item: Project (50475062) supported by the National Natural Science Foundation of China; project (2004-47-19) supported by the Natural Science Foundation of Chongqing City of China     

切削加工过程的仿真方法研究与实现

为提供虚拟的加工环境和验证工艺设计的正确性,对切削加工过程的计算机仿真方法进行了研究,以OpenGL作为图形支持系统,用VC++开发了切削加工仿真系统。该系统实现了车、铣、刨、磨等多种加工方式的仿真,可对刀具运动和材料切出情况进行实时监控,且可通过工艺参数(如切削速度、进刀量等)对切削过程进行控制,并能自动计算和优化切削时间、成本等参数。系统界面友好,操作方便,运行可靠,能有效地帮助工艺人员对整个加工过程进行直观的评估和验证。     

基于虚拟现实的数控切割系统场景可视化

针对研制的数控等离子切割系统复杂的设计、制造、加工过程 ,将虚拟现实技术引入到系统中 ,开发了一种实用的虚拟场景。在此场景中可实现切割系统的全部设计和制造活动 ,并结合面向对象的编程技术 ,实现数控切割系统在虚拟现实场景中的动态可视化 ,从而能够预先感知切割系统在设计、制造过程中可能出现的问题 ,并加以解决。实践证明了其可行性。     

Adaptive learning with guaranteed stability for discrete-time recurrent neural networks

To avoid unstable learning, a stable adaptive learning algorithm was proposed for discrete-time recurrent neural networks. Unlike the dynamic gradient methods, such as the backpropagation through time and the real time recurrent learning, the weights of the recurrent neural networks were updated online in terms of Lyapunov stability theory in the proposed learning algorithm, so the learning stability was guaranteed. With the inversion of the activation function of the recurrent neural networks, the proposed learning algorithm can be easily implemented for solving varying nonlinear adaptive learning problems and fast convergence of the adaptive learning process can be achieved. Simulation experiments in pattern recognition show that only 5 iterations are needed for the storage of a 15×15 binary image pattern and only 9 iterations are needed for the perfect realization of an analog vector by an equilibrium state with the proposed learning algorithm.     

Developing remanufacturing engineering, constructing cycle economy and building saving-oriented society

In the course of creating immense wealth, manufacturing industry has excessively consumed the resources and energy in the earth, and seriously polluted the environment. To take progress as the sustainable development way, save resource and improve environment, our nation has been advocating to construct the cycle economy and saving-oriented society. Taking the remanufacturing engineering as the representative, the “4R” rule (Reduce, Reuse, Recycle and Remanufacture) is the important measure to get the goal. Remanufacturing engineering is the industrialization of high-tech maintenance of the waste and worn productions, and is one of the most active factors in “4R”. The development of high and new technology takes the important effect to promote the remanufacturing engineering. Foundation item: Project (50235030) supported by the National Natural Science Foundation of China     

Novel manufacturing method of optical fiber coupler

Based on the coupling mode theory that the coupling ratio of fiber coupler changes periodically with center distance of two optical fibers, a novel manufacturing method of optical fiber couplers was developed with fused biconical taper experimental system. Its fabrication process is that the fiber is fused but not stretched when light begins to split, and the reduction of diameter of fiber is dependent on the theological characteristic of the fused fiberglass. The performance of the coupler was tested. The results show that the performance of the novel optical fiber coupler meets the performance expectations, and its diameter of coupling region （about 30 μm） is twice as long as that of classical fused biconical taper coupler （about 16 μm）, so the default, that is, the device is easy to fracture, is restrained and the reliability is greatly improved.     

Relationship between rheological manufacturing process and optical performance of optical fiber coupler

Through theoretical analysis and experiments, the viscoelastic mechanical model of optical fiber coupler in the process of fused biconical taper was established, and the numerical analysis in non-uniform temperature field was made. The results show that the rheological parameters, such as drawing speed and fused temperature, have a tremendous influence on stress distribution and performance of optical fiber coupler, especially the influence of fused temperature. The change of fused temperature by 5 ℃ can lead to the change of the maximum stress by 30% and stress difference by 20% in the same cross section. The change of temperature gradient by 3% can result in the change of stress difference by 90%. In the present condition of rheological technology, rheological defects such as crystallizations and microcracks are easy to generate in the optical fiber coupler.     

机械制造中的低碳制造理论与技术

主要介绍了机械加工过程中的低碳制造相关理论和技术方法.将机械加工低碳制造技术体系结构重点划分为产品低碳设计,低碳生产过程,低碳能源开发等3个部分.涉及了轻量化、模块化及生态化的产品设计方法;生产过程中的加工设备部件优化与零部件再造技术,先进工艺及切削技术与优化方法,高效生产模式及调度管理方法等低碳制造技术相关方面的内容...     

基于虚拟加工的数控车削过程优化

为了优化车削加工过程,提高加工效率,提出基于虚拟加工技术预测实际切削参数,采用数控程序优化实现数控切削过程优化的方法.应用轮廓多边形的工件模型表示法,研究车削过程中瞬时切削深度和切削速度的获取算法,进一步利用优化算法和数控程序修正,实现数控车削过程的优化.实际切削实验和分析对比表明:加工时间显著缩短,充分利用了机床加工能力,优化后的切削过程得到了改善,提高了加工效率。     

New anodizing process for magnesium alloys

Compact anodic films with high hardness and good corrosion resistance on magnesium alloys were prepared by a new constant voltage and arc-free anodizing process. The effects of anodizing parameters such as applied voltage and electrolyte temperature on the peak current density and the thickness of films were investigated. In addition, the morphologies and corrosion resistance of films were investigated by scanning electron microscopy and potentiodynamic polarization, respectively. The results show that the higher the applied voltage, the higher the peak current density and the thicker the films. However, too high applied voltage may result in breakdown of films and intense sparking which may deteriorate the properties of the anodic films and bring about unsafety. The new anodizing process can be applied in a wide range of temperature. The new anodic films have numbers of pores with the diameter of 0.5 - 5.0 μm which do not transverse the entire film.     

Four optimal design approaches of high-order finite-impulse response filters based on neural network

Four optimal approaches of high-order finite-impulse response(FIR) digital filters were developed for designing four types filters using neural network algorithms. The solutions were presented as parallel algorithms to approximate the desired frequency response specification. Therefore, these methods avoid matrix inversion, and make a fast calculation of the filter’s coefficients possible. The convergence theorems of these proposed algorithms were presented and proved to illustrate them stable, and the implementation of these methods was described together with some design guidelines. The simulation results show that the ripples of the designed FIR filters are significantly little in the pass-band and stop-band, and the proposed algorithms are of fast convergence.     

Development of Virtual Simulation System for Remote Collaborative Surface Machining

1 Introduction Many parts of aerospace ,automobile and mold industries are high precision and complex-shaped. There-fore ,it needs multi-axis machining. Multi-axis machining has advantages of i mproving efficiency and surfaceprecision,reducing production expense and shortening ti me to market . Although there are many advantages inmulti-axis machining,there are many steps on process planningfor complexsurface .And every step needs engi-neers to make appropriate decisions by their professional…     

Stability and nonlinear dynamic behavior of drilling shaft system in copper stave deep hole drilling

The stability and nonlinear dynamic behavior of drilling shaft system in copper stave deep hole drilling were analyzed. The effects of the fluctuation of the cutting force, the mass eccentricity and the hydrodynamic forces of cutting fluid could be taken into consideration in the model of drilling shaft system. Based on the isoparametric finite element method, the variational form of Reynolds equation in hydrodynamic fluid was used to calculate nonlinear hydrodynamic forces and their Jacobian matrices simultaneously. In the stability analysis, a new shooting method for rapidly determining the periodic orbit of the nonlinear drilling shaft system and its period was presented by rebuilding the traditional shooting method and changing the time scale. Through the combination of theories with experiment, the correctness and effectiveness of the above methods are verified by using the Floquet theory. The results show that the mass eccentricity can inhibit the whirling motion of drilling shaft to some extent. Foundation item: Project(2007CB707706) supported by the Major State Basic Research Development Program of China; Projects(2007E213, 2007E203) supported by the Natural Science Foundation of Shaanxi Province, China