汽车覆盖件模具结构CBD研究

分析了汽车覆盖件模具结构采用基于实例设计方法的原因 ,通过建立面向装配的实例模型和推理机制 ,以新型集成化CAD软件为平台 ,通过二次开发 ,建立起基于实例的汽车覆盖件模具结构智能CAD系统 ,成功地进行了基于实例的覆盖件模具结构智能设计。     

基于案例推理的折弯排序方法研究

本文以钣金折弯件为研究对象,提出了一种以知识库为基础,以推理机为核心来获取弯曲件折弯工序的方法。采用面向对象技术表示实例,创建了实例知识库。利用基于案例的推理(CBR)方法获取目标零件的折弯工序。该方法能够充分利用实例加工知识,减少了试折弯次数,从而提高了折弯工艺知识的利用率和折弯件的加工效率。     

基于实例的覆盖件冲压CAPP关键技术研究

实例信息描述和实例管理是CBR设计方法中两个重要环节。本文结合CBR技术在开发覆盖件冲压CAPP中的具体应用,重点讨论了这两个方面的内容,提出了建立覆盖件冲压工艺特征模型和覆盖件分类索引树的方法。     

利用UG／Open二次开发技术估算汽车覆盖件拉延毛坯尺寸

本文建立了覆盖件毛坯尺寸估算的数学模型，利用UG／Open二次开发技术，开发了相应的工具软件，并给出盒形件的分析实例以及发动机罩的实例。     

基于UG的修边翻边镶件参数化设计系统研究

分析了修边、翻边镶件的分类与结构特征,介绍了覆盖件修边、翻边镶件设计系统的结构,结合具体实例总结出镶件的设计流程,对一系列技术难点提出了解决方案,并基于UG OPEN API开发了汽车覆盖件修边翻边镶件设计系统,提高了镶件设计的效率。     

等高非规则拉深件的定义及计算方法

论述了等高非规则拉深件的定义及计算方法,介绍了椭圆拉深件的展开尺寸计算过程,并给出了具体的应用实例。     

基于UG的汽车覆盖件模具智能化标准件库的实现

以UG为开发平台,在充分考虑汽车覆盖件模具结构及其设计特点的基础上,以功能为向导,结合框架、产生式规则、实例的混合知识表示及推理模式,建立了以知识为基础的智能化的汽车覆盖件模具标准件库。本文描述了系统的框架结构及其实现方法,并给出了实例。     

浅析覆盖件表面常见变形的过程

通过对汽车覆盖件生产中常见的表面变形缺陷及产生原因进行分析,提出了解决覆盖件表面变形的有效方法,同时重点介绍了模具型面强压技术在覆盖件模具中的应用实例。     

铁路货车金属冷冲压件弯曲工艺浅析

介绍了铁路货车弯曲件类型及制造工艺,提高弯曲件工艺性、制造质量的方法,弯曲件工序排布及模具设计原则、注意事项,并配以实例进行讲解。     

等高非规则拉深件的定义及计算方法

论述了等高非规则拉深件的定义及计算方法,介绍了椭圆拉深件的展开尺寸计算过程,并给出了具体的应用实例。     

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.     

RESEARCH ON THE FORMATION MECHANISM OF INTERNAL CRACK IN THE CONTINUOUS CASTING SLAB

In view of the periodic bending deformation of solid-liquid interface in the solidification process for continuous casting slab, the variation of temperature gradient and dendritic spacing in the front edge of the solid-liquid interface, and the nucleation and propagation process of crack were studied. It is shown that the bending deformation of the interface results in the temperature field change in the front edge of solid-liquid interface, and the occurrence of temperature gradient along drawing direction results in the growth of secondary dendrites. The initial crack formed during the middle and final stage of solidification may extend to the surface of the casting slab and become an internal crack. The results of the theoretical analysis are basically in agreement with that of the experiment.     

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.     

A STUDY OF TEMPERATURE-DEPENDENT VALENCE BOND STRUCTURE OF TITANIUM

On the basis of energy and shape method for the determination of the valence bond (VB) structures of crystal, the valence bond structure of titanium is redetermined at room temperature and calculated in the whole temperature range of 0-1943K. The outer shell electronic distribution of Ti is e_c~(2.9907) · (s_c~(0.4980) d_c~(2.4927)) ef1.0093 in crystal. The temperature dependences of the VB structures of hcp and bcc phases are the same. The VB structures of hcp and bcc phases monotonically increase or decrease with the increase in temperature, but show discontinuous changes at the phase-transformation temperature 1155K.     

20钢渗硼过程中硼化物形核和生长的TEM观察及室温形变的影响SCIEI

本文采用单向减薄制样法在透射电镜下直接观察了20钢渗硼初期硼化物的形核和生长特性及室温形变的影响。X射线及电子探针分析结果表明:渗硼初期试样表层仅有Fe_2B形成;表层硼原子浓度与形变量之间具有单调增长的关系;偏聚于位错胞壁之中的硼原子阻碍了形变组织的恢复和再结晶,加速了硼化物的形核和长大。     

Influence of Fe on Microstructure and Mechanical Properties in Pdoped Ni–Cr–Fe Alloys

The influence of Fe on the microstructure and mechanical properties of P-doped Ni–Cr–Fe alloys has been investigated.Results showed that increasing Fe content refined the dendrite microstructure and enhanced the solubility of P in as-cast alloys. The change of microhardness in different dendrite regions was attributed to the segregation of P atoms in solid solution state, which had strengthening effects. Increasing Fe contents from 15.2 to 60.7 wt% reduced the yield strength and tensile strength but had little influence on the elongation of alloys. The stress rupture life of alloys after heat treatment decreased with the increment of Fe contents, and the failure fracture modes transferred from transgranular to intergranular fracture mode. The change of fracture modes was due to the weakness of grain boundaries caused by the increment of Fe.In addition, the precipitation of M_(23)C_6 was believed to be related to the segregation of P toward grain boundaries, which led to the fluctuation of carbon and chromium atoms near the grain boundaries in alloys with low Fe contents. Consequently, the increment of Fe decreased the strength of matrix and changed the existence of P atoms and the precipitates at grain boundaries.     

Antimony Induced Crystallization of Amorphous Silicon

Antimony induced crystallization of PVD (physics vapor deposition) amorphous silicon can be observed on sapphire substrates. Very large crystalline regions up to several tens of micrometers can be formed. The Si diffraction patterns of the area of crystallization can be observed with TEM (transmission electron microscopy). Only a few and much smaller crystals of the order of 1μm were formed when the antimony layer was deposited by MBE (molecular beam epitaxy) compared with a layer formed by thermal evaporation. The use of high vacuum is essential in order to observe any Sb induced crystallization at all. In addition it is necessary to take measures to limit the evaporation of the antimony.     

Theoretical Analysis for the Motion and Temperature of Melt Droplets in Spray Degassing Process

The motion of melt droplets in spray degassing process was analyzed theoretically. The height of the treatment tank in spray degassing process could be determined by the results of theoretical calculation of motion of melt droplets. To know whether the melt droplets would solidify during spraying process, the balance temperature of melt droplets was also theoretically analyzed. Then proof experiments for theoretical results about temperature of melt droplets were carried. In comparison, the experimental results were nearly similar to the calculation results.     

FE Simulation of Center Crack Occurrence in Tube Rounds During Two-Roll Rotary

With the aid of FE (finite element) code MSC.Superform 2005, 2-D coupled thermo-mechanical simulation of center-crack occurrence in round billet during 2-roll rotary rolling process was presented using Oyane ductile fracture criteria. A simple modeling is put forward based on the spiral motion of the workpiece as an essential characteristic in movement. The influence of the feed angle and the entry cone angle of the main roll on the process was taken into account in the modeling. The soundness for simplifying the 3-D rotary rolling into a 2-D problem was discussed. By adopting the parameters of Diescher piercer in 140mm mandrel mill of Bao Steel, the distribution and development of strain / stress were analyzed, and the eigen value of ductile fracture as well. The critical percentage of diameter reduction was obtained from the simulation. The result showed a good agreement with the experimental value, and therefore was of widely guiding significance to the practical process for rationally formulating the deformation parameters of steel tube piercing.     

Study of colored anodized aluminum with calcon in sulfuric acidic solution using cyclic voltammetry and impedance measurement methods

The effect of coloring condition of Al with Calcon (sodium 2,2'‐dihydroxy‐azonaphthalene‐4‐sulfonate), on the corrosion resistance of Al in 0.1 M sulfuric acid solution was studied, using cyclic voltammetry and measurement of impedance noise methods. The changes in the corrosion resistance of colored aluminum electrodes were evaluated by measuring the magnitude of impedance and cyclic voltammetric responses of anodized and colored electrodes. An irreversible corrosion response was observed at the cyclic voltammogram of the colored aluminum electrode. The current and threshold potential of corrosion responses strongly depends on the applied conditions during anodizing, coloring and sealing stages. In addition, significant changes in impedance at the ac voltammogram and noise level at some ac frequencies were observed, when the electrodes were colored under various conditions. In this regard, the surface of the electrode was studied by Scanning Electron Microscopy (SEM). Comparison of SEM images of the colored and uncolored aluminum specimens showed that the colored surface contained a significant numbers of pits. The results indicated that coloring aluminum with Calcon could reduce corrosion resistance of aluminum and increase roughness of the oxide film.