礼县出土春秋秦鼎的实验考古学研究——铸型工艺中的分体模与嵌范技术复原

商周时期中原地区的青铜圆鼎大多以三合范铸造,而礼县出土的三件春秋型秦式鼎特征鲜明,皆使用双合范浑铸成形。只有通过使用分体模和嵌范技术才能保证这种工艺得以实施。文章尝试将史前石器的研究范式用于青铜器研究;对器表能够反映古人特定技术行为和思维方式的工艺痕迹,进行了系统观察和痕迹分析;进而展开相关的实验考古学研究,对所作分析进行补充和验证,并通过实验考古这个直观的认知过程,将器物上的静态信息转化为动态的历史图景,揭示秦国铸工的生产方式和工艺思想。

分体式下模压印接头成形的有限元模拟及接头微观组织

采用有限元方法模拟了5052铝合金板的分体式下模压印连接过程,并与整体式下模压印过程的模拟结果进行了对比;对板料在分体式下模中的流动特征进行了模拟;对分体式下模压印接头阳极化覆膜后,利用微分干涉相衬法(DIC)对显微组织进行了分析,从微观角度观察分析了分体式下模压印连接成形过程中板料的流动。结果表明:模拟得到的分体式下模压印接头的颈厚和镶嵌量能较好地与试样的变形特征参数相符;压印接头区域的显微组织由原来的块状晶粒变成了纤维状,晶粒被拉长细化;分体式下模压印连接过程中板料流动的模拟结果与试验结果相吻合。

体绘制分体建模法建立人体股骨有限元模型

背景:股骨三维有限元研究建模方法有很多种,而采用体绘制分体建模方法至目前为止尚未见报道。目的:采用体绘制分体建模方法建立正常人股骨三维有限元实体模型,分析该建模方法的优越性。方法:将CT原始图像进行去噪等预处理后,建立正常人股骨三维有限元模型,模型包括皮质骨、松质骨及髓腔3部分解剖结构。再将皮质骨分为3种材料、松质骨分为6种材料,骨髓为单一材料属性分体建模,并行有限元力学分析。结果:采用体绘制分体建模方法建立的人股骨三维有限元模型包括皮质骨、松质骨及髓腔解剖结构。结论:采用体绘制分体建模比整体建模单一划分材料更接近真实情况,更符合有限元分析的要求。

蜡模分体组合工艺的应用

介绍了精铸生产中蜡模分体组合工艺及其应用 ,并提出了注意事项。蜡模分体组合工艺可降低模具设计、制造难度及制造成本 。

用分体压模实现汽车前桥横拉杆缩径

我厂在生产汽车前桥横拉杆时,原来采用对横拉杆两端同时施以径向力和轴向力两次收缩成形,现改为径向单向施力一次收缩成形,产品质量和生产效率显著提高。

几种异形骨架轴唇圈的模具设计

介绍了几种异形骨架轴唇圈的模具设计。双副唇外包胶骨架轴唇圈模具采用分体模芯结构 ,用热压冷芯法加工 ,解决了分体模芯结合部位的钻胶和拉毛问题。双唇和带侧唇骨架轴唇圈模具在轴唇圈侧唇顶端中心对应部位分型 ,并开设一个根部为 6 0°斜边的溢胶槽 ,确保了轴唇圈侧唇部位的尺寸精度。单唇外露骨架轴唇圈模具的模腔最大径向尺寸比骨架外径大 0 1mm ,且骨架的定位高度为骨架高度的 1/3,保证了胶料不外溢。模具选用的主要材料为 45 #碳素钢。

提高滑板模套使用寿命的技术方案

介绍并分析了原滑板模套使用寿命短的基本状况和原因,提出了通过优化模具材质和结构改进等方式提高滑板模套使用寿命的改进措施。

Molecular simulation study of the microstructures and properties of pyridinium ionic liquid[HPy][BF_(4)]mixed with acetonitrile

The microstructures and thermodynamic properties of mixed systems comprising pyridinium ionic liquid[HPy][BF_(4)]and acetonitrile at different mole fractions were studied using molecular dynamics simulation in this work.The following properties were determined:density,self-diffusion coefficient,excess molar volume,and radial distribution function.The results show that with an increase in the mole fraction of[HPy][BF_(4)],the self-diffusion coefficient decreases.Additionally,the excess molar volume initially decreases,reaches a minimum,and then increases.The rules of radial distribution functions(RDFs)of characteristic atoms are different.With increasing the mole fraction of[HPy][BF_(4)],the first peak of the RDFs of HA1-F decreases,while that of CT6-CT6 rises at first and then decreases.This indicates that the solvent molecules affect the polar and non-polar regions of[HPy][BF_(4)]differently.

弹性隔套制造工艺及模具设计

对弹性隔套的具体结构进行了研究,分析了该类鼓形零件的胀形特点及其传统生产工艺,设计了自动预压整体式弹性隔套胀形模,介绍了该模具的结构特点、工作过程及设计要点。该模具避免了之前产品坯料因变形大而造成内部微裂纹的缺陷,保证了弹性隔套的外形尺寸及性能要求,同时产能提升2倍以上。

整体喷嘴环的熔模铸造技术及机械加工工艺研究

由于整体喷嘴环熔模铸造后整体脱模困难,采用三维计算机软件CAD/CAM设计出整体喷嘴环分体式模具,开发了悬臂薄叶片喷嘴环K213高温合金整体浇注成型技术,并研究了高温合金难加工材料的加工方法。结果表明,经分体式模具制备的喷嘴环铸件无明显铸造缺陷,合格率达到70%;对喷嘴环的切削参数以及刀具进行合理选择,保证了表面加工质量和尺寸精度,提高了生产效率,降低了成本。

青铜器制造技术中的嵌范整铸

东周及汉代青铜器的制作技术中,常用鑞焊和铸接技术连接主体与附件。使用特定的连接技术,便会在制成的青铜器上呈现相应的工艺现象。本文所述器物的附件通常被认为是通过焊接或铸接与主体连接的,本文对这些案例进行了观察分析,认为其使用了嵌范整铸技术。

Application of molecular interaction volume model in separation of Pb-Sn-Sb ternary alloy by vacuum distillation

Based on the molecular interaction volume model （MIVM）, the activities of components of Pb Sn Sb ternary alloy were predicted. The vapo^liquid phase equilibrium of Pb-Sn-Sb alloy system was calculated using the activity coefficients of Pb Sn-Sb alloy system in the process of vacuum distillation. The calculated results show that the content of Sn in vapor phase increases with the increasing distillation temperature and content of Sn in liquid phase. However, the content of Sn in vapor phase is only 0.45% （mass fraction） while 97% in liquid phase at 1100 ℃, which shows that the separating effect is very well. Experimental investigations on the separation of Pb-Sn-Sb ternary alloy were carried out in the distillation temperature range of 1100-1300 ℃ under vacuum condition. It is found that the Sn content in vapor phase is 0.54% while 97% in liquid phase at 1100 ℃. Finally, the predicted data were compared with the experimental results showing good agreement with each other.

Finite element analysis of stress at implant-bone interface of dental implants with different structures

The effect of structure,elastic modulus and thickness of lower modulus layer in porous titanium implants on the stress distribution at the implant-bone interface was investigated.Three-dimensional finite element models of different titanium implants were constructed.The structures of the implants included the whole lower modulus style （No.1）,bio-mimetic style （No.2）,the whole lower modulus style in cancellous bone （No.3） and the whole dense style No.4.The stress distributions at bone-implant interface under static loading were analyzed using Ansys Workbench 10.0 software.The results indicated that the distribution of interface stress is strongly depended on the structure of the implants.The maximum stresses in cancellous bone and root region of implant No.2 are lower than those in the other three implants.A decrease in the modulus of the low modulus layer facilitates the interface stress transferring.Increasing the thickness of the low modulus layer can reduce the stress and induce a more uniform stress distribution at the interface.Among the four implants,biomimetic style implant No.2 is superior in transferring implant-bone interface stress to surrounding bones.

CFD-supported optimization of flow distribution in quench tank for heat treatment of A357 alloy large complicated components

The flow distribution in quench tank for heat treatment of A357 alloy large complicated components was simulated using FLUENT computational fluid dynamics（CFD） software.The flow velocity and the uniformity of flow field in two types of quench tanks（with or without agitation system） were calculated.The results show that the flow field in the quench tank without agitation system has not evident regularity.While as for the quench tank with agitation system,the flow fields in different parameters have certain regularity.The agitation tanks have a distinct advantage over the system without agitation.Proper process parameters were also obtained.Finally,the tank model established in this work was testified by an example from publication.This model with high accuracy is able to optimize the tank structures and can be helpful for industrial production and theoretical investigation in the fields of heat treatment of large complicated components.

Phase-field study for effect of chemical composition on pre-precipitation process of γ′ phase in Ni-Al-Ti alloy

The pre-precipitation processes of γ＇ phase in Ni-Al-Ti alloy with different chemical compositions are investigated by microscopic phase-field dynamics model. The simulation results show that the early precipitated phase with L10 structure is formed before the formation of γ＇ phase. With the increase of Al content, the composition of precipitated phase is transformed from the co-existence of γ＇ phase and material phase into single y phase. Furthermore, excessive Al content can stimulate the production of γ＇ phase, and the conversion time from L10 phase to L12 phase will lag behind other samples with lower Al con-tent. By analyzing the occupation probability of Ti, it can be found that the solid solution strengthening effect of Ti is reduced with the increase of Al component.

Computer aided stitching approach for dental restoration models

According to the bio-characteristics of the lower and upper cavity surfaces of dental restoration, a stitching approach is proposed based on a virtual zipper working mechanism and a minimization of the surface total curvature energy, which is used to resolve the stitching problems existing during computer-aided design for dental restorations. First, the two boundaries corresponding to the lower and upper surfaces are triangulated based on the zipper working mechanism to generate the initial stitching surface patch, of which the edges are distributed uniformly between the boundaries. Secondly, the initial stitching surface patch is subdivided and deformed to reconstruct an optimized surface patch according to the bio-characteristics of the teeth. The optimized surface patch is minimally distinguishable from the surrounding mesh in smoothness and density, and it can stitch the upper and lower cavity surfaces naturally. The experimental results show that the dental restorations obtained by the proposed method can satisfy both the shape aesthetic and the fitting accuracy, and meet the requirements of clinical oral medicine.

Simulation of texture evolution during plastic deformation of FCC,BCC and HCP structured crystals with crystal plasticity based finite element method

Two alternative formulations of single crystal plasticity model were introduced respectively and two schemes were implemented in the explicit FE code with software ABAQUS/Explicit by writing the user subroutine VUMAT.Meshes containing material data were created with solid elements.Each element represented an individual grain,and the grain orientations were explicitly stored and updated at each increment.Tangential modulus method was employed to calculate the plastic shear strain increment of deformation systems in combination with a hardening law to describe the hardening responses.Both two developed subroutines were applied to simulate the texture evolution during the uniaxial tension of copper（FCC）,cold rolling of IF steel（BCC） and uniaxial compression of AZ31 magnesium alloy（HCP）.The predicted texture distributions are in qualitative agreement with the experimental results.

Insight into Capture of Greenhouse Gas （CO2） based on Guanidinium Ionic Liquids

Quantum mechanics and molecular dynamics are used to simulate guanidinium ionic liquids. Results show that the stronger interaction exists between guanidine cation and chlorine anion with interaction energy about 109.216 kcal/mol. There are two types of spatial distribution for the title system： middle and top. Middle mode is a more stable conformation according to energy and geometric distribution. It is also verified by radial distribution function. The continuous increase of carbon dioxide （CO2） does not affect the structure of ionic liquids, but CO2 molecules are always captured by the cavity of ionic liquids.

CFD Simulation and Experimental Validation of Fluid Flow in Pre-distributor

Liquid distributor is a very import intemal for distillation columns. Pre-distributor is usually set on the top of distributor for initial distribution. Fluid flow in pre-distributor is a complex system of variable mass flow with many orifices and sub-branches. Consequently, the two phase modeling of pre-distributors was carried out andthe homogeneous model with free surface model was applied. The numerical method was validated by comparing with experimental data. Using the simulated results for different pre-distributors, the impacts of inflow rate, location and orientation uoon the outflow distribution were investigated. Furthermore, influences of the outflow distribution for pre-distributor on liquid uniformity in trough were also analyzed, The conclusions can De aaoptea for me structural design of liquid distributor and pre-distributor of large scale.

Automatically extracting sheet-metal features from solid model

With the development of modern industry, sheet-metal parts in mass production have been widely applied in mechanical, communication, electronics, and light industries in recent decades; but the advances in sheet-metal part design and manufacturing remain too slow compared with the increasing importance of sheet-metal parts in modern industry. This paper proposes a method for automatically extracting features from an arbitrary solid model of sheet-metal parts; whose characteristics are used for classification and graph-based representation of the sheet-metal features to extract the features embodied in a sheet-metal part. The extracting feature process can be divided for valid checking of the model geometry, feature matching, and feature relationship. Since the extracted features include abundant geometry and engineering information, they will be effective for downstream application such as feature rebuilding and stamping process planning.