FE simulation and process analysis on forming of aluminum alloy multi-layer cylinder parts with flow control forming

The aluminum alloy parts used in airbag of car were studied with flow control forming(FCF) method,which was a good way to low forming force and better mechanical properties. The key technology of FCF was the design of control chamber to divide metal flow. So, the design method of FCF was analyzed and two type of control chamber were put forward. According to divisional principle, calculation model of forming force and approximate formula were given. Then forming process of aluminum alloy multi-layer cylinder parts was simulated. The effect of friction factor, die radius and punch velocity on metal flow and forming force was obtained. Finally, the experiment was preformed under the direction of theory and finite element(FE) simulation results. And the qualified parts were manufactured. The simulation data and experimental results show that the forming sequence of inner wall and outer wall, and then the force step, can be controlled by adjusting the process parameters. And the FCF technology proposed has very important application value in precision forging.     

Developing of an expert system for nonferrous alloy design

Expert systems have been used widely in the predictions and design of alloy systems. But the expert systems are based on the macroscopic models that have no physical meanings. Microscopic molecular dynamics is also a standard computational technique used in materials science. An approach is presented to the design system of nonferrous alloy that integrates the molecular dynamical simulation together with an expert system. The knowledge base in the expert system is able to predict nonferrous alloy properties by using machine learning technology. The architecture of the system is presented.     

Design method of electromagnetic field applied to Al-alloy electromagnetic casting

The electromagnetic pump imposes the electromagnetic motive force （Lorentz force） on the liquid metal directly and makes it move along the definite direction by using the function of electric current and magnetic field in the conducting fluid. Compared with the traditional die casting, the system of counter-gravity casting can effectively control the speed of filling to make Al-alloy liquid fill steadily by adjusting controlled-current. So the foundry defects can be decreased or avoided effectively by this system. Based on the theory of electromagnetic pump, the design method of electromagnetic field in electromagnetic pump was investigated emphatically. The rule of magnetic induction intensity B influenced by the divided electromagnet airgap＇s size was founded. Furthermore, the empirical formula of magnetic induction intensity B in a magnetic airgap for an open magnet in the saturated state was deduced by mathematics regression analysis. Counter-gravity casting applied to the Al-alloy electromagnetic filling was developed with this method. Besides, the electromagnetism filling counter-gravity casting process of the turbo-charge blade wheel was also fixed. The eligibility rate of blade wheel produced by such technique can be increased to 98%. The casts have compact structure and excellent capability.     

Study on Design Techniques of a Long Life Hot Forging Die with Multi-Materials

A new design technique for the long life hot forging die has been proposed. By finite element analysis, the reason for the failure of hot forging die was analyzed and it was concluded that thermal stress is the main reason for the failure of hot forging die. Based on this conclusion, the whole hot forging die was divided into the substrate part and the heat-resistant part according to the thermal stress distribution. Moreover, the heat-resistant part was further subdivided into more zones and the material of each zone was reasonably selected to ensure that the hot forging die can work in an elastic state. When compared with the existing techniques, this design can greatly increase the service life because the use of multi-materials can alleviate the thermal stress in hot forging die.     

Finite element simulations of deformation behavior in equal channel angular pressing using a rotated die

A new die design for equal channel angular pressing (ECAP) of square cross-section billet was proposed by a 45 rotation of the inlet and outlet channels around the channel axes. ECAP utilizing the rotated and conventional dies was simulated in three dimensions using the finite element method. Conditions with different material properties and friction coefficients were studied. The billet deformation behavior was evaluated in terms of the spatial distribution of equivalent plastic strain, plastic deformation zone and load history. The results show that the rotated die appears to produce billets with a smaller deformation inhomogeneity over the entire crosssection and a greater average of equivalent plastic strain at the cost of a slightly larger working load. The billet deformation enters into a steady state earlier in the case of the rotated die than the conventional die under the condition of a relatively large friction coefficient.     

The contribution of solid-state chemistry in the determination of multicomponent phase diagrams

For a long period of time, the determination of phase diagrams was only supported by experiments related to thermal effects or thermodynamic measurements： thermal analysis, calorimetric measurements, vapor pressures, and EMF measurements. As a matter of fact, solid-solid transformations were not so accurately determined and could not be taken into account in the system＇s analysis. First, X-ray diffraction methods were used as a support for the thermal analysis. Second, the implementation of novel tools in structural analysis （for example, the Rietveld method） has permitted to increase the knowledge of phase stability. Finally, modeling the phases using a Calphad method needed increasingly more structural results to determine and better understand the phase diagrams. On the other hand, the Calphad method has been widely developed for metallic systems, for oxide systems, and in the past 10 years, for some semi-conductor systems, for example, gallium arsenide, cadmium telluride, and lead telluride systems. In such applications, it is very important to bring point defects in the modeling of the phases to map the defects as a function of the chemical composition. Owing to its complexity, this characteristic, the knowledge of which is crucial for the understanding and the control of potential physical applications, was ignored in the previous assessment of semi-conductor systems.     

STUDY ON THE NUMERICAL SIMULATION OF MULTI-STAGE ROTARY FORGING OF A NON-AXISYMMETRIC PART AND THE CAE ANALYSIS OF THE DIE STRENGTH

Traditionally a rotary forging process is a kind of metal forming method where a conic upper die, whose axis is deviated an angle from the axis of machine, forges a billet continuously and partially to finish the whole deformation. For the rotary forging process simulation, more researches were focused on simulating the simple stage forming process with axisymmetric part geometry. Whereas in this paper, the upper die is not cone-shaped, and the billet is non-axisymmetric. So the movement of the punch is much more complicated than ever. The 3D FEM simulation models for the preforming ＆ final forming processes are set up aider carefully studying the complicated movement pattern. Deform-3D is used to simulate the material flow, and the boundary nodal resisting forces calculated by the final stage process simulation is used to analyze the final forming die strength. The CAE analysis of the die shows that the design of the final forming die is not reasonable with lower pre-stress which is easy to crack at the critical corners. An optimum die design is also provided with higher pre-stress, and verified by CAE analysis.     

Real estate appraisal system based on GIS and BP neural network

For the inefficiency and inaccuracy of appraisal method of traditional estate appraisal theory, the real estate appraisal system based on GIS and BP neural network was established. The structure of the system was designed which includes appraisal model, trade case, GIS database and query analysis module. With the help of the L-M algorithm in MATLAB software, BP neural network was improved and the trade cases were trained, then the BP neural network which has already been trained was tested. At the same time, the BP neural and GIS were put together to construct the hedonic price estimate model. The C# and ArcGIS9.3 were used to achieve the system in VS2008. City basic geographic data and real estate related information were used as the basic data in practice. The results show that the functions of querying, adding and editing the spatial data and attribute data are achieved and also the efficiency and accuracy of real estate are improved, so that the new method of real estate is provided by the system.     

Design strategy of intelligent CAD for welding positioner scheme design

Traditional CAD technique does not support the design processes such as function definition, conceptual design and preliminary design, which are most creative and play significant roles on the design quality. Because scheme design has close relationship with product structure, peoCormance and technology cost, it is important for applying the intelligent CAD of scheme design to improve the quality and competitive level of the product. The definition and function of welding poKtioner are discussed in this paper. The new deflation of welding positioner extends the research scope of welding positioner to welding. fixture and welding positioning motion mechaniam. The design process of welding fixture and positionlng motion system is described, and the cased-based and knowledge-based design strategy of ,oelding positioner scheme design intelligent CAD is then put forward, which lays foundation for developing prow-type system of welding positioner scheme design.     

Diffusion bonding of Ti-6Al-4V by pulse current heating and hot-pressing

Pulse current heating （PCH） was used to join Ti-6Al-4V alloy at two cases of with die and without die. Hot-pressing （HP） method was used to provide a comparison between the two methods. Microstructures near the contacting surfaces were observed in optical microscope. Temperature distribution was analyzed. After joining, the tensile properties of the samples were evaluated. Experimental results show that grains and phases grow transversely on contacting surfaces, which makes two parts into a whole with a certain of tensile strength. PCH joining is a different temperature joining method. The highest temperature is located at the interface. The comparison of tensile strengths of samples joined by the two methods indicates that joining temperature and holding time needed by PCH are lower and less than those needed for HP.     

齿轮冷精密锻造智能CAD/CAM系统研究

以齿轮精锻工艺模具智能设计为研究对象 ,建立了集成智能设计系统的模型 ,将有限元分析方法与工艺、模具及电极设计的知识表示方法以及推理机制相结合 ,建立了回弹量预测的模糊神经网络 ,并应用于智能系统 ,开发出了相应的程序 ,并以实例进行了验证     

KBE技术在汽车覆盖件拉深工序件设计中的应用

拉深工序是汽车覆盖件成形的关键工序,拉深工序件的设计是覆盖件模具设计的一个瓶颈环节.为了解决覆盖件冲压工艺设计过程中经验和知识缺乏的问题,研究了知识工程技术（KBE）的实现机理和应用方法,通过总结覆盖件拉深工序件设计的知识和经验,建立了基于KBE的拉深工序件知识模型.通过将设计准则、经验和工艺约束等知识融入拉深件设计的各个组成要素中,实现了拉深工序件设计过程中知识的表达和知识的推理.在上述研究的基础上,以UG软件为平台,开发了基于知识的覆盖件拉深模具型面设计系统.KBE技术在拉深件设计的成功应用,提高了拉深件设计的自动化和智能化程度.     

Al-Si合金活塞金属型铸造工艺和模具设计智能化

为了开发Al-Si合金活塞金属型铸造工艺和模具智能化设计系统，在对国内外先进设计经验总结、归纳的基础上，采用面向对象的知识表达方法，建立了模块化的知识库。系统应用了基于实例的推理技术并建立了实例库和实例原型库。通过开发的文件接口程序，完成了一般设计型专家系统与传统CAD系统的连接，实现了智能化设计。通过与现场使用的设计方案比较，验证了本系统的有效性和实用性。     

冲模结构知识库知识与控制性知识的表示

根据模具设计知识的类型和特点,研究了ＣＲＢ系统中冲模结构知识库知识与控制性知识的表示方法,导出了符合工程设计习惯的冲模结构知识库知识表示方法－典型冲模结构特性图和与其对应的适合于ＣＢＲ推理的控制性知识表示方法－基于冲模结构特征的产生式规则表示。     

在注塑模设计系统中应用基于模型推理技术

构建了基于模型推理的注塑模设计智能软件系统，阐述了基于模型推理技术在注塑模设计中的应用，并给出实例进行了简要说明。     

面向对象的系统设计在压铸模CAD中的应用

将面向对象的知识表达方法应用于压铸模具的智能CAD系统中。将设计对象的属性、处理过程、启发性知识统一表示在对象结构中。模具设计的领域知识通过多重继承来实现。在知识系统的基础上完成了压铸模具的智能CAD系统设计。     

模具数控加工智能工艺规划与优化的技术框架

提出模具数控加工智能工艺规划与优化的技术框架,并从系统实现的技术和方法上进行了讨论。系统拟采用基于规则的推理和基于事例的推理方法,不仅可以帮助设计者完成工艺规划中的各项选择,还可以对工艺优化的过程进行指导,减少了优化算法的复杂性。根据工艺数据具有不精确和不完备的特点,拟采用模糊集和粗糙集进行规则和事例的提取。     

模具结构辅助设计Case智能推理系统

基于事例的推理技术ＣＢＲ是人工智能技术发展的重要领域之一,而大形事例库的检索,一般的索引法和最近邻主以达到快速、准确的检索要求,因此,有必要研究智能检索推理技术。本文根据事例学习的决策树ＩＤ３和ＰＩＤ算法,提出了多概念学习决策树ＭＮＩＤ算法,开发了基于事例学习的智能模具相似结构推理系统,燕应用于冲模凸模结构Ｃａｓｅ库的检索,效果很好,系统通过事例的自主学习,产生出推理规则,并能根据用户对所设计模具     

药筒精密成形工艺数字化设计系统

介绍了药筒工艺数字化设计系统的特点、设计流程和各功能模块的主要功能。该系统在药筒成形工艺和模具设计过程中融合了基于规则的推理与基于实例的推理,可智能完成工艺参数计算,半制品与模具参数化建模,同时为设计者提供有效的精密成形工艺设计知识和经验帮助,大幅提高了该类零件成形工艺和模具设计效率。     

基于知识的轴对称零件拉深设计支持系统

研究了复杂轴对称零件拉深工艺智能设计过程中知识获取、集成和应用的方法,包括基于形状单元的产品表示、基于设计手册的设计过程知识获取、基于仿真技术和机器学习技术的成形性能评价知识获取和设计参数调整与控制知识获取等,开发了基于知识的智能设计系统,引导设计人员快速、有效地完成轴对称壳体拉深件的设计,并通过一个设计实例验证了方法的可行性。