逆变弧焊机中IGBT的防护

本文介绍了ＩＧＢＴ逆变弧焊机中的过电压、过电流保护电路，包括外部过电压、内部过电压、输出过电流和ＩＧＢＴ器件过电流的防护措施。文中还就驱动电路的应用进行了讨论，以提高ＩＧＢＴ器件的使用可靠性。     

铜合金热挤压制品常见缺陷分析及预防措施

分析了铜合金热挤压制品常见缺陷的产生原因。如：裂纹和开裂、气泡和起皮、过热和过烧等。并提出了相应的预防措施，这些措施可确保产品质量，有显著的经济效益。     

过时效温度对2024铝合金形变后的再结晶行为和力学性能的影响

采用力学性能检测和透射电镜（TEM）观察，研究了过时效温度对2024铝合金形变后的再结晶行为和合金力学性能的影响。结果表明：过时效温度对合金力学性能的影响较大，在250～350℃的过时效温度范围内，随温度升高，合金强度提高，350℃时效时合金的性能最好，此时σb=580MPa，δ5=9．2％，比传统处理工艺（T62）分别提高32％和84％。其原因是过时效温度间接地影响了合金随后固溶再结晶的晶粒大小。因此，为了达到细化晶粒的目的，必须严格控制过时效温度。     

YL12铝合金的过烧组织及其力学性能

对YL12铝合金不同过烧情况下的组织进行了观察，指出其过烧时的特征组织是复熔球、晶界析出相、过烧三角区，过烧程度不同其特征组织不同。在发生轻微过烧时其性能未发生较大变化，过烧严重时，力学性能迅速下降。     

喷射成形过喷粉末形貌及组织研究

采用扫描电子显微镜和金相显微镜对喷射成形过喷粉末的形貌及组织进行了研究。结果表明，过喷粉末颗粒尺寸相对比较均匀，以球状、类球状形态存在，并且尺寸越小越圆整。过喷粉末颗粒多以异质形核为主，极少数小颗粒组织为同质形核，无论以何种方式形核，其内部组织均为树枝晶。     

40Cr钢活塞开裂原因分析

对40Cr钢活塞端面出现的锯齿状裂纹进行了检验和分析。结果表明，活塞开裂的主要原因是表面淬火加热时的局部温度过高，导致过热、过烧。     

2A12铝合金热处理工艺研究

对2A12铝合金进行了固溶、时效和过时效工艺试验，测定了经不同工艺热处理后合金的性能，建立了2A12合金过时效工艺与硬度之间的关系曲线。试验结果表明，固溶处理和自然时效后合金的强度和断后伸长率均比人工时效后的提高了36％，固溶处理并分级时效后合金的强度提高了50％。生产中，为获得100～120HB硬度的过时效工艺为270℃×2h，要进行校正的2A12合金薄板的最佳热处理工艺为240℃×6～8h。     

自动流量平衡阀可变过流面端帽的有限元分析

针对自动流量平衡阀可变过流面端帽受到高压流体冲击作用而产生的应力、应变损坏和共振现象，利用ANSYS对可变过流面端帽结构进行动力学建模和有限元分析，使强度、刚度满足材料使用要求。在有限元分析基础上，通过模态分析验证了有限元分析的结果，为今后自动流量平衡阀结构改进提供了必要的理论和技术依据．     

铸造中华精品 振兴民族品牌——访南通振康机械有限公司董事长汤子康先生

记者一行到达振康公司已过午饭时间，但汤总仍在等待着我们。用过午饭后，汤总便带我们参观工厂。车间里那一台台整齐排列的先进数控、程控生产加工设备和半自动流水生产线，工人们那认真、有序、高效的工作场景，组装车间那一台台各式各样、型号齐全的产品，厂区里那花园式的休闲场所，都给我们留下了深刻的印象。     

我国将扩大技术设备进口减少顺差

“近几年中国贸易顺差过快增长，引发了一系列矛盾和问题，当前要按照中央的部署，积极扩大先进技术设备进口，努力缓解贸易顺差过大的问题。”商务部副部长、国家机电产品进出口办公室主任魏建国在此间召开的全国机电科技产业商务工作会议上说。     

铝合金挤压制品常见缺陷分析及预防措施

分析了铝合金挤压制品常见缺陷产生原因，提出了相应的预防措施。这些措施可确保铝挤压制品，有显著经济效益。     

Application of neural networks to an expert system for cold forging

The technique of neural networks is applied to an expert system for cold forging in order to increase the consultation speed and to provide more reliable results. A three-layer neural network is used and the back-propagation algorithm is employed to train the network.

By utilizing the ability of pattern recognition of neural networks, a system is constructed to relate the shapes of rotationally symmetric products to their forming methods. The cross-sectional shapes of the products which can be formed by one blow are transformed into 16 × 16 black and white points and are given to the input layer. After learning about 23 products, the system is able to determine the forming methods for the products which are exactly the same or slightly different from the products used in the network training. To exploit the self-learning ability, the neural networks are applied to the prediction of the most probable number of forming steps, from information about the complexity of the product shape and the materials of the die and billet, and also to the generation of rules from the knowledge acquired from an FEM simulation. It is found that the prediction of the most probable number of forming steps can be made successfully and that the FEM results are represented better by the neural networks than by the statistical methods.     

带台阶及带凸(凹)槽制品的设计

结合硬质合金粉末的流动方式及影响其流动的各种因素 ,论述了带台阶及带凸 (凹 )槽制品的设计、压制与脱模     

基于CAXA的模具分模方法

在注塑模具中,分型面的设计将直接影响模具的复杂程度和制造成本,并对产品的质量产生影响.利用CAXA软件的自动分模功能绘制模具的草图或曲面从而分割型腔,可使模具按照给定的方式分模.通过一个零件,论述了采用CAXA进行分模的过程及其具体步骤.     

面向大规模定制生产的绿色模块化设计方法研究

大规模定制生产所面临的矛盾是,既要对外展现产品具有个性化的多样性,又不能因产品内部多样化而导致额外的成本和时间的延误.解决这一矛盾的关键是在产品设计中采用绿色模块化设计思想.本文将绿色设计思想与模块化设计方法有机结合,形成先进的绿色模块化设计方法.研究了绿色设计理念在面向大规模定制生产的产品模块化设计中的地位和作用,给出面向大规模定制生产的绿色模块化设计的具体步骤和方法.     

超低碳不锈钢冷轧（拔）无缝钢管生产工艺改进

介绍了采用Φ８０ｍｍ超低碳不锈钢轧坯经扒皮、穿孔、冷轧（拔）生产Φ５７ｍｍ以下成品管的工艺改进、新工艺要点，并对新工艺效果进行了浅析。     

基于COMET L3D三维结构光扫描仪的逆向技术研究

以某发电机端盖为例,介绍COMET L3D三维结构光扫描仪系统及点云数据获取的方法,描述了Geomagic Studio逆向软件对点云数据预处理的要点,重点探讨了发电机端盖这类铸造产品模型重构的步骤、方法以及注意事项,并进行了误差分析,最后获得了符合精度要求的数据模型。结果表明:通过借助COMET L3D三维结构光扫描仪对铸造产品进行逆向工程的研究,可在吸收原有逆向方法的基础上进行创新、改进,缩短新产品的研发周期。     

Precision forging of spur gears with inside relief

Conventional closed-die forgings as applied to the forging of spur gears require high forging pressure. In this paper, a precision forging technology has been developed for the forging of spur gears with alloy steel (SCM415). The technology developed includes two steps in the forging process. Well-shaped products are forged successfully using a lower forging pressure than that of conventional forging. The accuracy of the forged spur gear obtained by the new precision forging technology is set nearly equal to that of a cut spur gear of the fourth and the fifth classes in the Korean industrial standard.     

Cost-affordable titanium: The component fabrication perspective

Titanium is the material of choice for a wide variety of applications. However, because of its relatively high price—a result of extraction and processing costs—it is used only when it is the only choice. This paper will overview the potential areas that are amenable to cost reduction for titanium products, emphasizing all steps in component fabrication from extraction and processing to the fabrication of final parts.     

Oxidation of Mechanically Alloyed Al-rich Al–Ti Powders

The oxidation behavior of Al-rich, metastable mechanically alloyed powders in the Al–Ti binary system has been examined in the context of their potential application in high-energy-density materials. Scanning calorimetry and thermogravimetric analysis in an oxygen atmosphere up to 1500°C have been performed on powders, synthesized with compositions ranging from Al_0.95Ti_0.05 to Al_0.75Ti_0.25. Oxidation proceeds in three distinguishable steps, similar to the oxidation steps observed for pure aluminum. The steps become less pronounced with increasing Ti concentration. For both the first and second oxidation steps, the apparent activation energies are close to 400 kJ/mol. Partially oxidized material was recovered from intermediate temperatures for quantitative phase analysis by X-ray diffraction, Al₂O₃ and TiO₂ are the main oxidation products. Similarly to pure aluminum, metastable γ-alumina is present at temperatures below ∼ 1000°C, suggesting that the stepwise oxidation is related to phase transitions of the alumina in the oxide scale. At temperatures above 1300°C, oxidation follows melt formation in the binary Al–Ti system, as the aluminum component oxidizes selectively, leaving a titanium-rich metallic residue. No correlation was observed between the oxidation and melting of aluminum.