改善铁素体球铁曲轴切削加工性能的研究

为改善铁紊体球铁曲轴毛坯切削加工性能,分析探讨了铁素体的固溶强化机理,对材料的化学成分、力学性能和金相组织进行了分析比较。结果表明：影响铁素体球铁曲轴硬度的主要元素是硅,在试验范围内,铁素体球铁硅含量与其硬度成正比。通过调整硅含量,严格控制球铁中其它元素的含量并保持基体中铁素体数量的一致性,可以达到控制曲轴硬度,使铸造的曲轴毛坯完全满足自动化生产线对其切削加工性能的要求。     

硅元素对铁素体球铁曲轴硬度的影响规律

研完了稀土、锰和硅元素对冰箱压缩机铁素体球铁曲轴硬度的影响,并依据铁素体的固溶强化机理进行了理论分析。测试了球铁试样的力学性能,并观察了材料的金相组织。结果表明：影响铁素体球铁曲轴硬度的主要元素是硅。硅溶于铁素体（α-Fe）形成置换固溶体,造成晶格畸变,引起硬度提高。在试验范围内．铁索体球铁硅含量与其布氏硬度成正比关系。通过调整硅含量,控制曲轴的硬度达到140～160HB,满足了机加工对曲轴切削加工性的要求。     

曲轴内铣刀片的国产化

1　前言内铣是我厂曲轴加工的主要工序之一 ,也是汽车刀具国产化的一个重大项目。长期以来 ,该工序一直依赖进口国外刀片进行加工 ,刀具费用很高 ,1 997年仅曲轴内铣加工所耗刀具费用即达 1 50 2 7万元。因此 ,实现曲轴内铣刀片国产化是汽车行业机械加工中亟待解决的重要课题。　　2　曲轴加工难点2 1　毛坯情况差曲轴材料为 4 8ＭｎＶ ,硬度 2 33～ 2 77ＨＢ ,由于是锻件 ,毛坯表面硬度比内部高。内部组织为珠光体+铁素体 ,其中珠光体占 70 %以上 ,具体元素含量( % )如下 :Ｃ— 0 4 5～ 0 51 ,Ｍｎ— 0 9～ 1 2 ,Ｓｉ— 0 1 7～ 0 …     

面向21世纪的曲轴新材料

对发动机曲轴材料作了综合介绍。根据它的发展历史以及对各种种材料的化学成分、组织、性能、加工工艺、成本价格的比较分析,说明其发展趋势是以球铁曲轴替代锻钢曲轴,以铸态珠光体球铁曲轴替代热处理曲轴。球铁代钢的关键是提高韧性,自行研制的ＱＴ７４０－３铸态珠光体球铁曲轴表明,铸态球铁性能达到了一个新高新。另外对几种曲轴新材料进行了分析。     

球墨铸铁齿轮滚削性能的试验研究

本文探讨了铁素体、珠光体球墨铸铁齿轮的切削性能。经过对球铁击轮及45钢齿轮进行的切削试验和理论分析,证明球铁齿轮具有良好的切削性能;它与45钢齿轮相比,具有切削力小,切削功率低,轮齿表面质量好,刀具寿命长等特点。本文为球铁齿轮的工业应用,提供了加工工艺方面的试验数据.     

球铁曲轴激光淬火工艺的研究

介绍了激光淬火球铁曲轴与常规的曲轴表面处理方法相比有许多优点 ,提出了一种激光淬火球铁曲轴圆角部分扫描的新方法。通过优化激光淬火球铁曲轴的参数 ,对球铁曲轴进行了实验 ,实测了激光淬火后硬化层的深度、宽度及表面硬化层的硬度。实验还表明曲轴激光淬火前后变形量较小 ,抗疲劳性能优良 ,淬火带内存在较大残余压应力 ,且沿曲轴径向的淬火区与非淬火区相邻的一定范围内还存在一定的拉应力 ,证明了激光淬火球铁曲轴的可行性。     

球铁曲轴激光淬火工艺的研究

介绍了激光淬火球铁曲轴与常规的曲轴表面处理方法相比有许多优点,提出了一种激光淬火球铁曲轴圆角部分扫描的新方法。通过优化激光淬火球铁曲轴的参数,对球铁曲轴进行了实验,实测了激光淬火后硬化层的深度、宽度及表面硬化层的硬度。实验还表明曲轴激光淬火前后变形量较小,抗疲劳性能优良,淬火带内存在较大残余压应力,且沿曲轴径向的淬火区与非淬火区相邻的一定范围内还存在一定的拉应力,证明了激光淬火球铁曲轴的可行性。     

对球铁曲轴实行三包的情况和体会

我厂是以修理农机为主的农机修造厂。由于生产的需要,72年试制190曲轴,以解决修理缺件停机待料的问题。73年小批生产190曲轴。以后又陆续承担省、地195、290曲轴等生产任务。曲轴的材料是球墨铸铁的,起初由高州铸造厂供应球铁毛坯,我厂负责加工。75年在深入开展“工业学大庆”的群众运动中,经过反复试验,用本地资源——阳春生铁搞成了球墨铸铁,解决了曲轴毛坯靠外协解决的问题,掌握了生产主动权。几年来,我厂在搞好农机修理的同时,每年都超额完成上级下达的190、195、290球铁曲轴的生产任务。     

铸态铁素体球铁耐热疲劳性能的研究

本文研究了Ｓｉ、Ｍｏ合金元素对铸态铁素体球铁热疲劳性能的影响。当铸态铁素体球铁中含Ｓｉ量为３．１％左右时，能获得较佳的耐热疲劳性能；在此基础上加入适量的Ｍｏ元素可使其耐热疲劳性能进一步提高。     

硅对铁素体球铁机械性能的影响

本文研究了常温下硅对铁素体球铁机械性能与低温下硅对其冲击韧性的影响。为保证拖拉机在-40℃寒温下安全运行,提出了铁素体球铁Si终的控制指标与相应的工艺措施。     

Development and characterization of a wear resistant bainite/martensite ductile iron by combination of alloying and a controlled cooling heat-treatment

In this paper, a bainite/martensite (B/M) dual-phase ductile iron was fabricated by combining alloying and a controlled cooling heat-treatment. The microstructure, the mechanical properties and the wear performance were investigated and discussed. The ductile iron containing 3.2–3.8 wt.% carbon was alloyed with 2.5–3.0 wt.% manganese and 2.5–3.0 wt.% silicon. In general, manganese is no more than 0.7 wt.% and silicon <2.5 wt.% in commercial grade lower-bainite ductile irons. So, manganese contained in the ductile iron in this work is several times higher, and silicon slightly higher. In order to control the phase transition in the ductile iron during the heat-treatment, its continuous cooling transformation (CCT) curve was determined. The controlled cooling heat-treatment process was determined according to the CCT curve, which included three stages. The first stage was water quenching of the sample rapidly from the austenization temperature to a temperature below 350°C in a few minutes. The second stage was heat preservation of the sample from the spraying end temperature to 200°C in 2 h. The last stage was air cooling of the sample from 200°C to RT. According to the analysis using the scanning electron microscope (SEM) and the X-ray diffraction (XRD), the matrix of the ductile iron had a microstructure of bainite, martensite and a little retained austenite. The hardness and impact toughness of the heat-treated ductile iron were HRC 51.5 and 21.7 J/cm², respectively. The high values of the hardness and toughness were attributed to (1) the refined structure, (2) the presence of B/M dual-phase and (3) the presence of retained austenite. The impact abrasive wear resistance of the B/M ductile iron was observed to be comparable with that of a high chrome cast iron, and twice that of Mn13 steel.     

高合金抗磨铸铁渣浆泵叶轮的高速切削技术

分析了高合金高硬度抗磨铸铁材料性能和加工工艺性,讨论了其对加工刀具的要求,介绍了聚晶立方氮化硼（PCBN）材料的优点,使用PCBN刀具,通过合理选择切削用量和刀具技术参数,可以实现高硬度抗磨材料切削加工。     

An experimental study on microcutting of silicon using a micromilling machine

Micro-end-milling can potentially create desired 3D free-form surface features on silicon using ductile machining technology. A number of technological barriers must be overcome for micro-end-milling to be applied in the cutting of single crystal silicon. To produce smooth surfaces on brittle materials, such as silicon, it is important that the material be machined in the ductile mode. A major limitation of machining brittle materials is that the process of removing the material can generate subsurface damage. We have carried out an experimental study to find the optimum cutting conditions for obtaining ductile regime machining using a micromilling machine. The ductile and brittle regimes in the machining of silicon using diamond-coated end mills were demonstrated by machining grooves. The force ratio, F_t/F_c, was used to determine the milling performance on silicon. The experimental data show that the dominant ductile cutting mode was achieved when F_t/F_c?>?1.0.     

高Si-Mo球铁的高温性能

通过对高Si-Mo球铁及其它铸铁材料高温条件下的抗氧化、抗生长性能的测试,表明高Si-Mo球铁有良好的耐高温性能,其抗氧化、抗生长性随含碳量的减少和含Si量的提高而增加。球状石墨、铁素体基体的铸铁有良好的耐高温腐蚀性能。     

压缩机曲轴断裂失效分析

针对天然气压缩机的球墨铸铁曲轴的断裂事故进行了失效分析,通过对曲轴的断口形貌和铸造材质缺陷分析,判断出曲轴断裂属于过载脆性断裂,曲轴材质的铸造大气孔、疏松和粗大石墨相是造成曲轴断裂的主要原因,并提出了预防措施。     

激光冲击处理对曲轴磨损性能的影响

利用激光冲击波对曲轴球墨铸铁进行表面强化处理,利用摩擦磨损试验机研究激光冲击处理球墨铸铁QT700的磨损性能,利用金相显微镜分析激光冲击处理后其表面微结构,同时采用XRD分析激光冲击处理后球墨铸铁表面马氏体与残余奥氏体的含量。结果表明,激光冲击处理后球墨铸铁具有理想的表面形貌和较高的表面硬度,其抗磨性能大幅度提高,有利于提高其疲劳寿命。     

曲轴加工工艺分析

随着机械加工技术及设备的不断完善、切削刀具性能的不断提高,曲轴的加工工艺也在不断改进,本文从曲轴加工技术的现状、采用车-车拉数控加工方法的曲轴加工工艺实例,以及曲轴复合加工技术等方面就曲轴的机械加工工艺进行了分析。     

Crankshaft surfaces: Finishing methods,surface characterization and their influence on wear

In the gasoline or diesel internal combustion engine the surfaces which the crankshaft presents to the connecting rod and the main bearings are very important in determining the wear rate of the bearings. Nodular iron crankshafts, which are now used almost exclusively in automotive gasoline and diesel engines, are particularly sensitive to variations in finishing technique. The microstructure of the nodular iron crankshaft contains spherical graphite nodules surrounded by ferrite. When improperly finished, the ferrite can form a burr which protrudes above the surrounding surface. The prevalence, size and directionality of these ferrite burrs have a marked influence on the wear rate of the bearings. A large burr lying in the unfavorable direction can act as a file on the soft bearing material. Burrs can also impede formation of a suitable oil film, causing high bearing wear rates and reduced service life.     

普通车床滚压钻井泵曲轴过渡圆弧方法

曲轴是钻井泵传动系统的关键部件,在主轴颈和曲柄颈的过渡圆弧处易出现应力集中,影响曲轴的使用寿命。本文介绍了一种普通车床滚压钻井泵曲轴过渡圆弧的方法,重点讨论专用偏心夹具的设计和工作原理,详细分析了定位精度;并提出为降低表面粗糙度,提高工件的表面硬度、耐磨性和抗疲劳强度,曲轴主轴颈和曲柄颈各过渡圆弧采用滚压加工代替曲轴磨床的方案;最后分析了普通车床滚压曲轴的特点。