汽车桥壳机械式胀形关键技术

采用汽车桥壳机械式胀形新工艺,利用DEFORM-3D有限元软件对汽车桥壳机械式胀形过程进行数值模拟,分析成形管件的成形规律,并在现有设备上进行了相关物理实验。研究结果表明,机械式胀形桥壳的工艺孔两端区域受到拉应力的作用而出现壁厚减薄现象,中间区域受压应力的作用而产生起皱缺陷。通过采用以椭圆形工艺孔替代长工艺孔,同时在工艺孔中间区域设计三角槽的改进方案,其成形效果表明,改进的工艺方案有效的缓解了工艺孔两端区域的壁厚减薄的程度,同时避免了中间区域起皱的缺陷。     

基于柔性滑动分体式型腔模具的环形件内高压胀形研究

针对具有小半径圆角的薄壁环形件的内高压胀形工艺存在所需内压过大和零件贴模程度差的问题，提出了传统内高压胀形以及基于柔性滑动分体式型腔模具的内高压胀形两种成形工艺。分析了在相同加载路径下两种成形工艺的有限元模拟结果，确定了基于滑动分体式型腔模具的内高压胀形工艺方案为较优方案。采用正交试验探究了进给量、最大内压和保压时间对成形件的胀形高度和最大壁厚减薄率的影响，并对试验结果进行了极差分析，结果表明，进给量和最大内压分别是胀形高度以及最大壁厚减薄率的最大影响因素。对试验结果进行综合分析得到了最优方案，即进给量19 mm、最大内压80 MPa和保压时间1 s。采用最优方案进行了试验，结果显示该方案可成形出合格的零件，测量成形件的壁厚分布并与有限元模拟结果进行了对比，有限元模拟结果与试验结果的壁厚减薄趋势基本相符。     

多曲率截面TC4钛合金超塑性胀形工艺

为研究多曲率截面TC4钛合金超塑性胀形过程中成形气压加载速度对零件成形效果的影响，利用MARC有限元软件对TC4钛合金板材在应变速率为2×10^-3 s^-1条件下进行了超塑性胀形模拟，获得了气压-时间加载曲线。基于该曲线设计了3种不同成形气压加载速度曲线，并分别进行了超塑性胀形试验。试验结果表明，在3种不同成形气压加载速度条件下，气压加载速度越慢，零件成形效果越好。零件各个位置壁厚变化均匀且实际壁厚减薄趋势与模拟得到的壁厚减薄趋势大致相符，零件实际最大壁厚减薄率约为25%,满足零件使用要求。成形后的零件各变形区域的晶粒形状变化不大且均为等轴晶粒，晶粒尺寸随着板材形变量的增大而减小。     

汽车驱动桥壳液压胀形数值模拟及试验研究

利用ABAQUS软件建立桥壳液压胀形工艺的有限元模型,对汽车桥壳的预胀形和终胀形过程进行了数值模拟,并分析了不同的加载路径对桥壳成形的影响规律。模拟结果表明:预胀形阶段,胀形压力保持30 MPa不变,管坯发生轻度失稳形成三鼓形样件,合模后胀形压力增大至60 MPa,内凹部分贴模得到较好壁厚分布的预胀形管坯;终胀形初期,胀形压力保持20 MPa不变,轴向进给量达到30 mm后快速增大至120 MPa,可以成形出合格的样件。采用Q345B无缝钢管进行物理实验,获得了符合尺寸要求的桥壳样件,验证了数值模拟的可靠性。     

镀锡钢薄壁罐胀形壁厚变化分析

为了提高薄壁罐气压胀形的成形质量,减少壁厚严重减薄而产生皱折、破裂等成形缺陷,使用钣金成形专用软件模拟薄壁罐气压胀形过程。分析了成形3个阶段金属流动情况、壁厚变化、应力和应变分布规律以及罐坯成形极限,中间阶段对胀形结果影响明显,壁厚减薄、应力和应变的最大值发生在胀形的最大变形区。试验验证与模拟分析吻合。     

工艺参数对双层304不锈钢波纹管液压胀形的影响

为提高波纹管的成形质量以及合理选取胀形工艺参数,基于有限元分析软件ABAQUS模拟304不锈钢双层波纹管液压胀形过程,并利用实验验证了有限元模型的正确性。基于建立的模型,研究了内压力、模具行程、挤压速度和加载路径对波纹管成形的影响。结果表明,影响双层波纹管液压胀形壁厚减薄和波高的主要工艺参数为内压力和模具行程;随着内压力和模具行程的增大,最大壁厚减薄率和波高均线性增大,且内外层壁厚差值增大;过大的内压和挤压速度会导致波高不均匀性增大;降低起波阶段内压力及在成形初期施加轴向进给的加载路径有利于减小波纹管的减薄率。最后,通过双层波纹管的液压胀形实验验证了数值模拟的正确性。     

半滑动式液压胀形汽车桥壳的模具设计及成形

提出了半滑动式液压胀形模具的设计原则,并针对某小型汽车桥壳设计了终胀形模具和两种结构方案的预胀形模具;使用ANSYS软件数值模拟桥壳的液压胀形成形过程,重点分析模具型腔对成形的影响,比较了两种预胀形模具对成形管坯的壁厚变化及成形性的影响;在普通液压机上试制出汽车桥壳样件。     

镁合金摩托车手把管超塑胀形工艺研究

设计了一套镁合金管材胀形成形装置,对镁合金摩托车手把管的超塑性胀形成形进行了实验研究,并通过实验确定了镁合金管超塑胀形的成形工艺.其主要工艺参数为:成形温度340～370 ℃,胀形初始压力2.0～2.2 MPa,轴向压力1.0～1.5 MPa,随着胀形的进行,胀形压力分阶段逐步加载到10MPa.在此工艺条件下,成形出的管子尺寸精度高,壁厚均匀,无减薄现象.用超塑性胀形技术提高了镁合金的塑性成形能力,并实现了摩托车手把管的精密成形,提高了材料利用率,降低了成本.     

汽车桥壳机械式胀形数值模拟及实验

基于有限元分析软件MARC平台建立汽车桥壳胀形三维有限元模型,采用理论分析、计算机数值模拟和物理实验相结合的方法研究桥壳机械式胀形工艺。对该工艺坯料变形区的受力状态,及易产生折叠和拉裂的潜在区域进行分析与预测,获得金属流动、应力应变分布及壁厚的变化规律;采用无缝钢管在630kN压力机上进行物理实验,验证工艺方案的可行性。实验结果表明,采用机械式胀形工艺方案试制的桥壳成形效果较好,测量的壁厚分布规律与有限元模拟结果吻合,可为桥壳批量化生产提供参考依据。     

加载方式对汽车桥壳压制成形的影响

针对某中型卡车桥壳胀压成形工艺中预成形管坯压制成形过程,给定几种不同的外压及内压加载方式;利用有限元软件ABAQUS对压制成形过程进行数值模拟,通过比较桥壳制件成形后的贴模性、壁厚分布,揭示外压和内压加载方式对压制成形的影响;并进行预成形管坯的压制成形工艺实验,实测了样件的外形及壁厚,实验结果与有限元模拟结果相吻合。     

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.     

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.     

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).     

Quantitative Analysis of the Crystallographic Orientation Relationship Between the Martensite and Austenite in Quenching–Partitioning–Tempering Steels

The orientation relationships(ORs)between the martensite and the retained austenite in low-and medium-carbon steels after quenching–partitioning–tempering process were studied in this work.The ORs in the studied steels are identified by selected-area electron diffraction(SAED)as either K–S or N–W ORs.Meanwhile,the ORs were also studied based on numerical fitting of electron backscatter diffraction data method suggested by Miyamoto.The simulated K–S and N–W ORs in the low-index directions generally do not well coincide with the experimental pole figure,which may be attributed to both the orientation spread from the ideal variant orientations and high symmetry of the low-index directions.However,the simulated results coincide well with experimental pole figures in the high-index directions{123}_(bcc).A modified method with simplicity based on Miyamoto’s work was proposed.The results indicate that the ORs determined by modified method are similar to those determined by Miyamoto’method,that is,the OR is near K–S OR for the low-carbon Q–P–T steel,and with the increase of carbon content,the OR is closer to N–W OR in medium-carbon Q–P–T steel.     

The Mirror with Patterns of Auspicious Animals and Grapes——Exquisite cast mirror and the technology of surface tin-enrichment by rubbing-in and infiltration of tin-rich powder

<正>Bronze mirrors were used by the Chinese people before the introduction of the glass mirror.Only after it was replaced by the glass mirror did the bronze mirror gradually retreat from people's lives.Different styles of bronze mirrors were made in different historical periods,particularly in the Warring States Period,the Han and Tang Dynasties,which were the three peaks of the development of bronze mirror arts in ancient China.The casting techniques were exquisite.The surface of the bronze mirror was smooth and bright enough to reflect one's image,and there were scarcely any casting defects on the mirror surface.On the back of the bronze mirror,there were rich depictions of Arts and Humanities,and the ornamentations were also     

The 9th China International Diecasting Congress & Exhibition

The 9th China International Diecasting Congress ＆ Exhibition was held on July 22-24, 2014 at Shanghai New International Expc Centre. This exhibition was the most successful over the years, with over 6890 visitors and 155 exhibitors, and the exhibition area increased by 30% from 9,500 square meters in 2012 to 12340 square meters. Die casting enterprises from a total of 24 countries and regions, including China mainland, Chinese Taiwan and Hong Kong, South Korea, Japan, Germany, India, Thailand, Malaysia, the United States, Russia, Australia, Iran, Ukraine, Brazil, Colombia, Singapore, Austria, Canada, Croatia, France, Turkey, United Kingdom, Vietnam, attended the congress and exhibition.     

Introduction of the Fluid Control Engineering Institute of Kunming University of Science and Technology

正The Fluid Control Engineering Institute of Kunming University of Science and Technology was set up in 1996.The researches of institute concentrate on electro-hydraulic(pneumatic)servo/proportional control and hydromechatronics.The Institute is committed to research and development of electro-hydraulic control of high-end technical equipment in ferrous metallurgy refining produc-     

RARE METALS Volume Contents

正~~     

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.     

A CUMULATIVE FATIGUE DAMAGE RULE UNDER THE ALTERNATIVE OF CORROSION OR CYCLIC LOADING

Fatigue damage increases with the applied loading cycles in a cumulative manner and the material deteriorates with the corrosion time. A cumulative fatigue damage rule under the alternative of corrosion or cyclic loading was proposed. The specimens of aluminum alloy LY12-CZ soaked in corrosive liquid for different times were tested under the constant amplitude cyclic loading to obtain S-N curves. The test was carried out to verify the proposed cumulative fatigue damage rule under the different combinations among corrosion time, loading level, and the cycle numbers. It was shown that the predicted residual fatigue lives showed a good agreement with the experimental results and the proposed rule was simple and can be easily adopted.