DF7C型机车涡轮增压器的更新

简要介绍DF7C型机车涡轮增压器更新方案和ZN250—3C型涡轮增压器性能结构特点。     

ZN系列增压器新型推力轴承的研制及运用

介绍了研制的新型空间曲面油楔结构的推力轴承及采用的新材料,并在轴承表面进行特殊涂镀。提高了推力轴承的承载力及耐磨性,延长了推力轴承使用寿命。同时,优化了ZN系列增压器推力轴承组装结构,使轴承组件数目减少70％以上,减少了系统误差。新型推力轴承首先在ZN315增压器上装车运用,已走行了37万km,增压器状态良好。运用情况表明,推力轴承改进后,提高了增压器使用可靠性,延长了使用寿命。     

ZN9烟支在线检测装置的改进

对ZN9烟支在线检测装置中存在的漏气烟支有效剔除率低,检测帽易损坏的问题进行了原因分析,提出的解决方法是①对检测气压电路进行改进,实现了检测空气的适时关闭;②使用弹性好的检测帽,并定期对检测帽、检测管、检测鼓进行检查和清理.     

On solidification and shrinkage of brass alloys

Abstract

The solidification process was investigated in brass alloys containing a wide range of zinc, between 32·5 and 47·1 wt-%. A series of solidification experiments was performed under different cooling rates using differential thermal analysis (DTA) and a confocal mirror furnace. The cooling rate and the solidification under cooling temperature were evaluated from cooling curves. Furthermore, the peritectic reaction was studied in view of the starting and the ending temperatures and shrinkage behaviour. The volume change was measured in the peritectic alloys using a dilatometer which was developed to investigate the melting and solidification processes. A theoretical analysis was developed to evaluate the volume change effect on the peritectic reaction.     

Chemical and structural properties of ancient metallic artefacts: multitechnique approach to study of early bronzes

Abstract

The results are presented of a characterisation study of the microstructure and microchemistry of archaeological bronze (Cu–Sn) artefacts from the eighth to the sixth century bc. Metallographic examination, with optical and electron optical microscopy, has been performed on polished sections of early Iron Age studs and bracelets found in incineration tombs of the Necropolis of Chiavari in Italy. A heterogeneous microstructure of the bronze was observed, exhibiting a wide range of grain sizes, and a predominant α-phase solid solution containing α/δ and α/? eutectoid phases decorated with a high density of inclusions. The composition of grain boundary surfaces was determined, using scanning Auger microscopy (SAM), on specimens fractured in vacuo. The extent of tin segregation at the grain boundaries was 3–5 times greater than that in the grain interiors. Copper rich sulphides occasionally containing the oligoelements (iron and lead) were identified as the predominant type of inclusions formed at the grain interfaces and within the grains. Analysis of the corrosion patina at the surface of the bronze artefacts was conducted by combining X-ray diffraction, scanning electron microscopy with energy dispersive X-ray analysis, and SAM. The patina was found to exhibit a multilayered structure and a complex chemical composition forming various crystallographic phases including malachite, cuprite, and copper–tin oxide. Corrosion of the underlying bronze matrix proceeded along the grain boundaries, where the sacrificial corrosion of tin reacting with diffused oxygen and chlorine was identified. The results of this study have been used to clarify the metallurgy and manufacturing processes of the examined finds, and to evaluate the state of their degradation.     

Microstructures formed from mixed solders on copper substrate

Abstract

With the development and use of a variety of Pb free solders, it is probable that some solder joints in electronic assemblies may be made with solders of two different compositions. To investigate possible microstructures resulting from such procedure, samples were prepared using small balls of four different Sn–Ag–Cu (SAC) Pb free solders, as well as Sn–Zn–Al solder, melted together with eutectic Pb–Sn solder paste and also various SAC solder pastes, on a copper substrate. It was observed that using eutectic Pb–Sn solder paste with an SAC solder ball introduced some Pb–Sn eutectic microstructure and changed the ternary eutectic present from Ag₃Sn–Cu₆Sn₅–Sn to Ag₃Sn–Pb–Sn. Use of an SAC solder paste with Sn–Zn–Al solder introduced an apparent Ag–Cu–Zn ternary compound, replacing Zn lamellae of the Sn–Zn eutectic. With eutectic Pb–Sn solder paste, the Pb–Sn–Zn ternary eutectic was formed. It was noted that use of a high Sn solder results in rapid dissolution of the copper substrate.     

ZN-1阻尼材料的粘接工艺研究

通过改变阻尼材料和硬铝的表面处理方式、使用钛酸丁酯偶联剂和添加金属纷末填料等方法，研究了TC1#和J22两种环氧树脂胶粘剂对ZN—1阻尼材料与硬铝的粘接工艺。实验表明：使用环氧胶粘剂TC1#，用硫酸—氨水法处理ZN—1阻尼材料表面，用240目砂纸打磨并用丙酮擦洗硬铝表面，以及添加钛酸丁酯偶联剂于胶样中，可使试样拉伸强度和剪切强度均提高到大于0．8MPa，与酒精处理阻尼材料和80目砂纸打磨硬铝的方法相比使粘接强度提高了33％以上。     

双导程ZN蜗杆修缘成形磨削研究

双导程ZN蜗杆(又称法向直廓蜗杆)修缘的精密加工需要研究一种成形磨削方法。传统的蜗杆修缘磨削方法是根据加工经验对砂轮进行手工修形,加工效率低且难以实现高精度的齿形修缘磨削。为此,以ZN蜗杆修缘齿形的成形磨削为目标,在蜗杆法平面引入齿形修缘分析,建立ZN蜗杆修缘齿形的数学模型,依据空间啮合原理计算出蜗杆磨削的成形砂轮截形,并利用数控砂轮修整装置修整砂轮。为验证蜗杆修缘的成形磨削效果,选用实际生产中的某一双导程ZN蜗杆,在自主研制的数控砂轮修整系统和工厂的蜗杆磨床上进行试验,经过对成形磨削砂轮计算、修整和蜗杆磨削,结果表明,磨削蜗杆的修缘量满足预期设计要求,蜗杆齿形精度达到6级。表明该方法可用于双导程ZN蜗杆修缘的高精度成形磨削。     

12V240ZJ型柴油机用新型ZN270B型增压器的研制

针对12V240ZJ型柴油机原装ZN285型增压器存在的效率低、跟随性差和壳体漏水等问题,研制了新型ZN270B型增压器。通过设计新型压气机叶轮、涡轮及出气壳体,使ZN270B型增压器整机效率提高了2％,转子重量减轻22％,壳体的漏水问题得到有效解决。ZN270B型增压器与12V240ZJ型柴油机匹配,在长期运用中证明性能良好,结构可靠,产生了明显的社会效益。     

ZN蜗杆成形磨削的砂轮修整器设计与软件实现

成形磨削是未来精密蜗杆加工的发展趋势,其中砂轮截形的精确计算是保证蜗杆加工精度的前提,首先制定了ZN蜗杆和砂轮的坐标系,并依据空间齿面啮合原理建立了磨削模型,推导了ZN蜗杆加工时的砂轮的理论廓形,即金刚盘的运动轨迹。其次,基于VB+Access平台,设计了完整的砂轮修整器控制系统,用户只需输入要加工蜗杆的基本参数,即可得到修整砂轮时所用的数控加工G代码。软件采用模块化设计。最后经实验验证,精度达到要求。为后续数控蜗杆磨床的设计提供一定的理论依据。