快速数控编程系统的制造特征构建研究

针对快速数控编程系统中不同CAD模型的特征识别和构建,论述了基于STEP文件的特征识别技术及其实现过程:首先利用词法分析器解析STEP中性文件,按照STEP的文件拓扑结构生成属性邻接图(AAG);在总结典型结构件拓扑特征基础上,结合数控编程切削逻辑,以切削级为基础进行特征识别和特征构建;最后以XML形式构造制造特征森林以供CAM系统使用.实例证明了文中方法的有效性,提高了结构件数控编程的效率和质量.     

变型零件快速数控编程工艺研究

为了实现变型零件的快速编程,分析变型零件数控程序快速编制的特点,研究数控快速编程中的关键工艺问题,提出了能实现数控程序快速变型的加工特征划分、排序方法,设计刀具参数、切削参数合理选择和自动变更工艺系统,在此基础上,构建工艺决策支持模块,为数控快速编程提供支持.     

基于经验的数控工艺知识挖掘算法研究

针对目前基于标准工艺模板的数控工艺复用方法在模板自动提取的研究中未考虑零件几何信息的问题，直接基于实例零件的复用方法存在检索效率低，提出将数据挖掘技术应用于数控工艺知识。利用三维极半径曲面余弦、正弦矩结合三维包络盒信息实现零件几何信息的数值化表达；选取关键加工参数并与几何信息进行关联，获得结构化的数控工艺数据。选用k-medoids聚类算法结合主成分分析和自编码器2种降维方法对历史工艺数据进行聚类分析以获得典型工艺模板，并以注射模电极零件为例，验证了方法的有效性和实用性。     

基于宏程序的数控参数化编程方法研究

参数化编程是使用变量参数进行数控编程的一种方法,通过2个典型零件在华中系统下的数控编程,对相似形状类和相似加工类零件基于宏程序的参数化编程的方法进行了研究。此方法提高了系列零件编程的质量和效率,降低了整体生产成本。     

变型零件快速数控编程方法

为了快速获得变型零件的数控加工程序,提出一种基于零件族数控程序母模板快速派生出变型零件数控加工程序的编程方法.首先分析、研究了零件的变型设计过程和数控编程原理,对加工特征进行了定义和划分,以零件族母模型加工特征为单元进行数控加工信息的组织,设计并构建零件族数控程序母模板,然后在零件事物特性表的驱动和工艺决策库的支持下,由零件族数控程序母模板自动生成变型零件的数控加工程序,实现变型零件的快速数控编程.最后通过实例验证了这些原理和方法的可行性.     

基于实例推理的模具高速加工编程辅助系统开发

在CAD/CAM软件中应用创建好的模板文件进行模具高速加工编程可以实现工艺知识快速套用,提高编程效率.该文开发了一个基于实例推理的网络化编程辅助系统,利用基于实例推理技术,将以前数控编程与加工中积累的工艺参数和经验以编程模板形式存储在数据库中,为新的零件提供参考解决方案,通过简单的特征输入,快速选择适用的编程模板进行编程.     

基于工艺特征的数控编程方法研究

以零件的工艺特征为基础,系统地研究了不同的机械加工工艺的编程方法。基本编程实现了机械加工工艺数控指令化。固定循环简化了典型加工工艺单元的编程,加工相同工艺内容用子程序编程,加工函数面用变量编程,加工零件族系列零件用参数化编程,加工自由曲面用CAM自动编程。同时通过数控编程技术的综合应用,实现了粗/精加工、自由平面轮廓倒圆角等工艺。     

基于加工特征的舵机壳体孔系特征数控加工编程技术

为提升舵机壳体数控加工编程效率、缩减编程重复性工作量,提出了基于加工特征的舵机壳体零件数控加工编程技术。通过分析舵机壳体的加工特征及其制造工艺,建立了舵机壳体自定义特征库和数控加工工艺知识库,并利用特征识别技术,自动识别舵机壳体的数控加工特征,之后基于加工工艺知识库推理生成每个特征的数控加工工艺和刀位轨迹,最后以某型舵机壳体为例,验证了文中所提技术的可行性和有效性。     

基于特征识别的型腔零件数控自动编程系统的研究

型腔零件的数控编程工艺比较复杂,一般情况下是通过人机交互完成的,编程效率不高。本文通过分析型腔零件的几何工艺特征,对零件建立属性邻接图,利用子图匹配局部工艺特征,并结合相关参数选择规范完成对加工操作的加工对象和操作参数的设置,同时利用标准化的工艺模板,实现加工工艺与加工顺序的自动匹配,最终自动完成零件的数控编程。     

基于Edgecam的在线测量和动态补偿自动编程技术研究

为了提高数控加工的效率,针对数控加工中的刀具参数和毛坯定位问题,提出了基于Edgecam软件的在线测量和动态补偿的自动化程序编制方法。首先,构建了在线测量和动态补偿编程系统,然后论述了系统体系结构设计、数据库连接和自动编程等关键技术,利用VB.NET、PCI和PDI等二次开发语言编制了程序,最后以某典型零件实例证明了该方法的有效性,实现了制造的智能化和快速化。     

Effects of Post-weld Heat Treatment on Microstructure,Mechanical Properties and the Role of Weld Reinforcement in 2219 Aluminum Alloy TIG-Welded Joints

In as-welded state, each region of 2219 aluminum alloy TIG-welded joint shows diff erent microstructure and microhardness due to the diff erent welding heat cycles and the resulting evolution of second phases. After the post-weld heat treatment, both the amount and the size of the eutectic structure or θ phases decreased. Correspondingly, both the Cu content in α-Al matrix and the microhardness increased to a similar level in each region of the joint, and the tensile strength of the entire joint was greatly improved. Post-weld heat treatment played the role of solid solution strengthening and aging strengthening. After the post-weld heat treatment, the weld performance became similar to other regions, but weld reinforcements lost their reinforcing eff ect on the weld and their existence was more of an adverse eff ect. The joint without weld reinforcements after the post-weld heat treatment had the optimal tensile properties, and the specimens randomly crack in the weld zone.     

新型的治疗阿尔茨海默氏症药物(1-二甲基磷酰基-2,2,2-三氯)-乙基-1-醇烟酸醋对体外神经细胞的作用

目的: 观察本实验室合成的一种治疗阿尔茨海默氏症(AD)的药物(1-二甲基磷酰基-2, 2, 2 -三氯)-乙基^-1-醇烟酸醋(NMF),对体外培养的皮层神经细胞活性的影响以及对海人藻酸(KA)所致的神经损伤的保护作用。方法: 采用体外培养皮层神经元的方法,解剖分离 15 d胚胎小鼠皮层神经细胞, 接种于 96孔板,48 h 后加药并培养 72 h,以 MIT 法 观察 NMF 对小鼠皮层神经细胞活性的影响;同时将接种于 24 孔板的细胞预先给予 NMF,d 3 时加或不加KA处理后,以台盼蓝染色鉴别并计数死、活细胞,可得出细胞的存活率。结果: NMF 明显促进胎鼠皮层神经元活性,其中 NMF1、0. 1、10nmol·L^-1促进神经元活性增殖率分别高达 34.7%、37.4%、36. 7%, NMF 明显促进正常胎鼠皮层神经元存活卒,与对照组比较,10nmol·L^-1 NMF 对皮层神经元的存活率分别提高 39.3%、73.5%。 NMF能显著 对抗 KA 所致的神经元损伤,与 KA 损伤组相比, NMF0.1、10、10nmol·L^-1对损伤皮层神经元的保护率分别为 77.30%、80.10%、84.15%。结论: NMF 明 显促进胎鼠皮层神经元的洁性、提高正常皮层神经元,的存活卒,并能有效地保护KA所致的神经元损伤,提示 NMF 是一种很有潜力的治疗 AD 的药物。     

The First Phase of the SRIF Industrialized Base in ＂West Area＂ Has Been Put into Operation

After nearly two years＇ tense construction, the first phase of industrialized base of Shenyang Research Institute of Foundry （SRIF）, located at the Tiexi Casting and Forging Industrial Park in the west of Tiexi District, has now been completed and formally put into operation.     

THERMODYNAMICS STUDY ON THE DECOMPOSITION OF CHROMITE WITH KOH

Institute of Process Engineering, Chinese Academy of Sciences, China, has proposed a method for oxidative leaching of chromite with potassium hydroxide. Understanding the mechanism of chromite decomposition, especially in the potassium hydroxide fusion, is important for the optimization of the operating parameters of the oxidative leaching process. A traditional thermodynamic method is proposed and the thermal decomposition and the reaction decomposition during the oxidative leaching of chromite with KOH and oxygen is discussed, which suggests that chromite is mainly destroyed by reactions with KOH and oxygen. Meanwhile, equilibrium of the main reactions of the above process was calculated at different temperatures and oxygen partial pressures. The stable zones of productions, namely, K2CrO4 and Fe2O3, increase with the decrease of temperature, which indicates that higher temperature is not beneficial to thermodynamic reactions. In addition, a comparison of the general alkali methods is carried out, and it is concluded that the KOH leaching process is thermodynamically superior to the conventional chromate production process.     

INFLUENCE OF HEAT TREATMENT ON DAMPING BEHAVIOUR OF THE MAGNESIUM WROUGHT ALLOY AZ61

The effect of isochronal heat treatments for 1h on variation of damping, hardness and microstructural change of the magnesium wrought alloy AZ61 was investigated. Damping and hardness behaviour could be attributed to the evolution of precipitation process. The influence of precipitation on damping behaviour was explained in the framework of the dislocation string model of Granato and Lücke.     

Three-Dimensional Growth of Coherent Ferrite in Austenite: A Molecular Dynamics Study

Coherent second phase often exhibits anisotropic morphology with specifi c orientations with respect to both the second and the matrix phases. As a key feature of microstructure, the morphology of the coherent particles is essential for understanding the second-phase strengthening eff ect in various industrial alloys. This letter reports anisotropic growth of coherent ferrite from austenite matrix in pure iron based on molecular dynamics simulation. We found that the ferrite grain tends to grow into an elongated plate-like shape, independent of its initial confi guration. The fi nal shape of the ferrite is closely related to the misfi t between the two phases, with the longest direction and the broad facet of the plate being, respectively, consistent with the best matching direction and the best matching plane calculated via the Burgers vector content(BVC) method. The strain energy calculation in the framework of Eshelby's inclusion theory verifi es that the simulated orientation of the coherent ferrite is energetically favorable. It is anticipated that the BVC method will be applicable in analysis of anisotropic growth and morphology of coherent second phase in other phase transformation systems.     

Effect of Rare Earth Doping on Impedance,Modulus and Conductivity Properties of Multiferroic Composites:0.5(BiLa_xFe_(1-x)O_3)–0.5(PbTiO_3)

The Lanthanum-doped bismuth ferrite–lead titanate compositions of 0.5(Bi LaxFe1-xO3)–0.5(Pb Ti O3)(x = 0.05,0.10,0.15,0.20)(BLxF1-x-PT) were prepared by mixed oxide method.Structural characterization was performed by X-ray diffraction and shows a tetragonal structure at room temperature.The lattice parameter c/a ratio decreases with increasing of La(x = 0.05–0.20) concentration of the composites.The effect of charge carrier/ion hopping mechanism,conductivity,relaxation process and impedance parameters was studied using an impedance analyzer in a wide frequency range(102–106Hz) at different temperatures.The nature of Nyquist plot confirms the presence of bulk effects only,and non-Debye type of relaxation processes occurs in the composites.The electrical modulus exhibits an important role of the hopping mechanism in the electrical transport process of the materials.The ac conductivity and dc conductivity of the materials were studied,and the activation energy found to be 0.81,0.77,0.76 and 0.74 e V for all compositions of x = 0.05–0.20 at different temperatures(200–300 °C).     

Using Finite Element and Contour Method to Evaluate Residual Stress in Thick Ti-6Al-4V Alloy Welded by Electron Beam Welding

This work was to reveal the residual stress profile in electron beam welded Ti-6Al-4V alloy plates(50 mm thick) by using finite element and contour measurement methods.A three-dimensional finite element model of 50-mmthick titanium component was proposed,in which a column–cone combined heat source model was used to simulate the temperature field and a thermo-elastic–plastic model to analyze residual stress in a weld joint based on ABAQUS software.Considering the uncertainty of welding simulation,the computation was calibrated by experimental data of contour measurement method.Both test and simulated results show that residual stresses on the surface and inside the weld zone are significantly different and present a narrow and large gradient feature in the weld joint.The peak tensile stress exceeds the yield strength of base materials inside weld,which are distinctly different from residual stress of the thin Ti-6Al-4V alloy plates presented in references before.     

Microstructures and Tensile Properties of Ultrafine-Grained Ni–(1–3.5) wt% SiC_(NP) Composites Prepared by a Powder Metallurgy Route

Silicon carbide nanoparticle-reinforced nickel-based composites(Ni–Si CNP),with a Si CNPcontent ranged from1 to 3.5 wt%,were prepared using mechanical alloying and spark plasma sintering.In addition,unreinforced pure nickel samples were also prepared for comparative purposes.To characterize the microstructural properties of both the unreinforced pure nickel and the Ni–Si CNPcomposites transmission electron microscopy(TEM) was used,while their mechanical behavior was investigated using the Vickers pyramid method for hardness measurements and a universal tensile testing machine for tensile tests.TEM results showed an array of dislocation lines decorated in the sintered pure nickel sample,whereas,for the Ni–Si CNPcomposites,the presence of nano-dispersed Si CNPand twinning crystals was observed.These homogeneously distributed Si CNPwere found located either within the matrix,between twins or on grain boundaries.For the Ni–Si CNPcomposites,coerced coarsening of the Si CNPassembly occurred with increasing Si CNPcontent.Furthermore,the grain sizes of the Ni–Si CNPcomposites were much finer than that of the unreinforced pure nickel,which was considered to be due to the composite ball milling process.In all cases,the Ni–Si CNPcomposites showed higher strengths and hardness values than the unreinforced pure nickel,likely due to a combination of dispersion strengthening(Orowan effects) and particle strengthening(Hall–Petch effects).For the Ni–Si CNPcomposites,the strength increased initially and then decreased as a function of Si CNPcontent,whereas their elongation percentages decreased linearly.Compared to all materials tested,the Ni–Si CNPcomposite containing 1.5% Si C was found more superior considering both their strength and plastic properties.     

Directional Growth of Tin Crystals Controlled by Combined Solute Concentration Gradient Field and Static Magnetic Field

A new method was introduced to achieve directional growth of Sn crystals. Microstructures in liquid(Pb)/liquid(Sn) diffusion couples were investigated under various static magnetic fields. Results show that the β-Sn crystals mainly reveal an irregular dendritic morphology without or with a relatively low static magnetic field(B0.3 T). When the magnetic field is increased to 0.5 T, the β-Sn dendrites close to the final stage of growth begin to show some directional character. With a further increase in the magnetic field to a higher level(0.8–5 T), the β-Sn dendrites have an enhanced directional growth character, but the dendrites show a certain deflection. As the magnetic field is increased to 12 T, the directional growth of the β-Sn dendrites in the center of the couple is severely destroyed. The mechanism of the directional growth of the β-Sn crystals and the deflection of the β-Sn crystals with the application of static magnetic field was tentatively discussed.