采用气雾化Zn-22%Al粉末挤压制造微型螺旋齿轮(英文)

基于Zn-22%Al共析合金的超塑性,采用粉末挤压工艺制造微型螺旋齿轮,以减小成形压力和获得细小的显微组织。该螺旋齿轮的规格为:模数0.3,齿数1.2,螺旋角15°。将粉末压制坯通过烧结和固溶热处理进行致密化。致密化的坯料由层状和细晶状组织组成。在温度250°C,应变速率2.36×10-3和1.18×10-1s-1的条件下对坯料进行挤压,并对挤压成形的螺旋齿轮的力学性能进行测试。     

圆柱斜齿轮锻造成形技术

介绍了圆柱斜齿轮塑性成形的2种方法,滚轧成形与浮动凹模成形。针对2种成形工艺,分别以不同型号的圆柱斜齿轮为对象进行了数值模拟与试验研究,探索了齿轮在不同工艺下,金属流动规律、成形缺陷及成形力等。结果表明：圆柱斜齿轮采用滚轧成形可有效避免脱模困难,且整个过程属于局部加栽,对设备要求简单。浮动凹模成形可有效降低成形载荷,较传统工艺载荷下降近30个百分点,脱模时,锻件齿形在模腔内沿螺旋方向做刚性平移运动,一定程度上保证了锻件的精度。     

Recent developments in the application of tin

As a commodity, tin has weathered a severe drop in its market value, and, at present, tin-producing countries are exporting more of the metal than was originally anticipated. Tin is utilized in a variety of significant applications, including: solder, where it has grown at the expense of lead; tinplate for food cans, where the battle between aluminum and steel is still being waged; coatings, where tin-zinc alloys are more corrosion resistant than zinc alone; and chemical production, where tin is used as a flame retardant and stabilizer in polymers. Fluctuations in tin prices would most adversely influence the fledgling chemical market, where the growth opportunities for tin diminish as the metal’s price escalates.     

Forging of helical gears: Upper bound analyses and experiments

In this paper, forging of helical gears has been investigated. The forging process of helical gears has been classified into two types of operations: guiding and clamping. The two types of forging of helical gears have been analyzed by using the upper-bound method. Kinematically admissible velocity fields have been developed in which an involute curve has been introduced to represent the tooth profile of the gear. Numerical calculations have been carried out to investigate the effects of various parameters such as module, number of teeth, helix angle and friction factors on the forging of helical gears. Some forging experiments were carried out with commercial aluminum alloy to show the validity of the analysis. Good agreements were found between the predicted values of the forging load and those obtained from the experimental results.     

利用轴承偏心套调整斜齿轮副的接触状态

针对硬齿面重载减速机,详细分析了利用轴承偏心套调整圆柱斜齿轮副接触状态的原理,并结合生产实际提出切实可行的操作规程。新方法减小了斜齿轮副接触状态调整的原理误差,能有效消除斜齿轮传动的偏载,从而提高重载齿轮的使用寿命。     

Recent developments in ceramic nanocomposites

Ceramic nanocomposites are drawing considerable interest as processing methods are developed to enable these materials to go from the research laboratory scale to the commercial level. The potential benefits of ceramic nanocomposites can be substantial, but further research is needed. In-depth characterization is also needed in order to understand the novel physical and mechanical properties of these materials. In the literature dealing with mechanical properties, there are still many controversies to be resolved. S. Bhaduri earned her M.S. in metallurgical engineering at the University of Idaho in 1995. She is currently a doctoral candidate at the University of Idaho. S.B. Bhaduri earned his Ph.D. in materials science and engineering at the University of New York at Stony Brook in 1981. He is currently an associate professor at the University of Idaho. Dr. Bhaduri is also a member of TMS.     

A computer design aid for internal spur and helical gears

This paper describes an interactive program to design internal gear pairs. From a specification, the program first performs a kinematic analysis to determine tooth numbers and to satisfy centre distance requirements, and then proceeds to calculate the facewidth. It is possible to call up any design standard in order to stress the gears; that used here is the British standard. Calculated facewidths are compared with design practice and, if outside accepted bounds, the program will after tooth numbers, or module or request a change in gear material. A complete design is provided, which includes all the necessary information for manufacture. Where the design specification places tight tolerances on centre distances and/or gear ratios, the program automatically makes the required centre distance and tooth profile corrections. On every occasion the program will find a satisfactory solution, or guide the user towards one. The program is flexible and allows the experienced designer maximum freedom to direct the design. The program contains many built-in databases, such as standard tooth cutters and material properties, and will draw the gear pair if required.

The paper describes the design method and the structure of the program and a sample design is given and compared with a manual design to the same requirement.     

Recent developments in the treatment of spent potlining

Since potlining has been declared a hazardous waste by the U.S. Environmental Protection Agency, primary aluminum producers are being faced with regulations that prescribe how spent potlining must be treated before being landfilled. In this respect, cost-efficient processes and methods have been developed during the last several years. These developments are reviewed in this article.     

Recent developments of shearing in Japan

In this article, leading research and development activities of shearing in Japan are reviewed. Main contents are elucidation of shearing mechanism, theoretical analysis, tool life, burr-free blanking, precision shearing, bar cropping, pipe cutting, slitting, shearing of non-metallic materials, tool making, shearing of extremely thin sheets, etc.     

Recent developments of bending in Japan

Developments and researches concerning bending in Japan during the last ten years can be divided into three major subject matters; bending of plates, bending of pipes and bending of channels. In binding, of plates, the problems of forming pipes from plates by using the U-O method have been treated by practising engineers and researchers, so the forming conditions have been confirmed. On the other hand, new processes to manufacture long tubes or pipes by the successive U-O bending, a method of in-plane bending with rolling and so on, have been proposed. An analysis for bending which has been considered with sharing deformations has been presented too. In bending of pipes, experimental and theoretical researches for plastic bending of pipes have been carried out. In bending of channels, uniform bending and stretch forming for channel products have been researched experimentally and theoretically. In the following chapters, the researches and developments about the above three major subject matters of bending are described in detail.     

Recent developments in the progress of superalloy 718

Among the commercially available superalloys, 718 stands out as the most dominant alloy in production. Currently, 718 accounts for as much as 45 percent of wrought nickel-based alloy production and 25 percent of cast nickel-based products. As an introduction to the September International Symposium on Superalloys (the program precedes this article), the following focuses on 718’s status in four key areas: clean-melt practice, resistance to low-cycle fatigue, thermomechanical processing, and alloy optimization.     

螺旋伞齿轮塑性成形试验研究

试验研究了汽车差速器主动螺旋伞齿轮塑性成形方法，设计并制造出试验用模具，在万 能拉伸试验机上进行了塑性成形实验，用网络实验研究了塑性成形齿轮截面上的金属流动情况及齿型充满过程，揭示了金属纤维走向与分布，测绘了塑性成形螺旋伞齿轮铅试件的行程压力曲经，为优化预制坯、成形模具结构设计和力能参数计算提供了实验依据。     

斜齿圆柱齿轮旋转精冲过程模具磨损模拟分析

在Deform-3D软件平台上建立了斜齿圆柱齿轮旋转精冲成形三维刚塑性有限元模型.基于Archard磨损模型对精冲过程进行了凹模模具磨损分析,得到了模具工作表面各点的磨损分布,确定了最大磨损发生区域,并与直齿圆柱齿轮精冲模具磨损进行了对比分析.通过单因素变量法,研究了反顶力、压边力、冲裁速度、凸凹模间隙、凹模圆角半径以及凹模初始硬度对模具磨损的影响关系.研究结果表明,磨损模型能准确预测旋转精冲过程中主要工艺参数与磨损之间关系,并从工艺设计方面提出了减小模具磨损的措施.     

先进板材液压成形技术及其进展

文章立足于板液压成形这种先进成形技术,面向创新,介绍了其原理及特点,并分类探讨了板液压成形技术最新进展,指出了今后的发展趋势。     

中空消音螺旋管挤出模设计

以排水管的中空消音螺旋管为研究对象,制定了中空消音螺旋管成型工艺的优化方案,介绍了优化设计的要点,设计的中空消音螺旋管挤出模,结构简单,成本低,生产效率高,易于加工,不易损坏,使用寿命长。