铸铁螺旋斜轧的包络法孔型设计

在铸铁螺旋斜轧轧辊设计中，本文采用啮合原理进行复杂孔型容积计算。提出了包括轧辊倾角、喇叭口倾角与轧辊直径在内的多余金属系数的新算法，为轧辊设计与调整提供了理论依据。     

轴承钢球毛坯热斜轧成形过程数值模拟

轴承钢球毛坯螺旋孔型斜轧工艺设计和变形行为较为复杂,传统的解析计算和物理试验方法不能有效揭示其轧制变形机理。探讨总结了钢球毛坯热斜轧成形主要建模技术与方法,基于SIMUFACT有限元软件平台首次建立了钢球毛坯热斜轧成形三维热力耦合有限元仿真模型。基于有限元模拟结果详细分析了轴承钢球毛坯热斜轧成形过程等效应变、应力、温度和轧制力能参数的分布与演变规律,证明钢球毛坯斜轧心部疏松或空洞缺陷的产生是由其在轧制过程承受的循环交变切应力、较高水平的横向拉应力和由多向拉应力引起的较大负静水压应力(正的平均应力)共同作用的结果。     

斜轧圆锥滚子轴承内圈毛坯的数值模拟及分析

热态斜轧圆锥滚子轴承内圈毛坯的生产效率显著高于常用的平锻和锤上胎锻工艺,材料利用率更高。基于DEFORM有限元分析平台,建立了螺旋孔型斜轧内圈毛坯的三维实体模型,对斜轧内圈毛坯的过程进行模拟计算,分析了轧件内部的应力-应变分布情况,为模具的设计和工艺参数的确定提供参考。     

斜轧圆锥滚子轴承内圈毛坯的数值模拟及分析北大核心

热态斜轧圆锥滚子轴承内圈毛坯的生产效率显著高于常用的平锻和锤上胎锻工艺,材料利用率更高。基于DEFORM有限元分析平台,建立了螺旋孔型斜轧内圈毛坯的三维实体模型,对斜轧内圈毛坯的过程进行模拟计算,分析了轧件内部的应力-应变分布情况,为模具的设计和工艺参数的确定提供参考。     

斜轧波纹管轧辊螺旋孔型数学建模与仿真

对轧辊斜轧波纹管这一过程进行运动分析,根据曲面包络理论并结合空间坐标变换法对斜轧波纹管轧辊螺旋孔型曲面方程进行研究,获得其数学模型。然后利用MATLAB软件对轧辊螺旋孔型曲面数学模型进行描述,得到孔型曲面的一系列数据,编辑程序对孔型曲面的相关数据进行处理,再将处理后的数据导入到PROE软件中,建立轧辊三维模型。最后将轧辊三维模型导入到VERICUT软件中,以轧辊模型为刀具对不锈钢管材进行轧制加工仿真,验证轧辊模型的可行性与有效性。     

螺旋孔型斜轧连接颈应力的研究

针对螺旋孔型斜轧球墨铸铁的轧制缺陷之一——连接颈的早断 ,分析了连接颈部分所受外力的分布状况及其数学式 ,并以 3 0 mm的球墨铸铁磨球为例进行了计算 ,给出了在三种情况下的连接颈应力变化曲线 ,由此判断最大应力发生的部位 ,而且分析了轧辊直径对连接颈应力的影响曲线。分析轧制产品可知 ,计算结果比较令人满意。最后 ,给出了轧制 3 0 mm磨球时轨辊直径的选取范围     

轴承套圈坯料螺旋孔型斜轧成形数值模拟及分析

针对传统解析计算和物理试验不能有效揭示轴承套圈坯料螺旋孔型斜轧工艺轧制变形机理的问题,基于Abaqus/CAE有限元分析软件建立轴承套圈坯料螺旋孔型斜轧成形三维有限元模型,其关键点为设置轧辊与轧件网格表面为面接触以及网格内部表面为自接触,采用高温单向拉伸试验确定韧性断裂模型中坯料的损伤参数,添加STATUS变量输出控制网格畸变等,并分析了轧制过程中坯料的应变和应力以及轧辊的轧制力和力矩,结果表明坯料内部区域处于多向拉应力状态,易导致内部微缺陷的萌生和扩展。     

球磨钢球斜轧孔型的设计

球磨钢球与其他零件轧制生产一样，轧制过程的顺利与否、轧件质量的优劣，其主要关键之一是合理的孔型设计。介绍斜轧钢球孔型设计基本参数的选取。     

张力减径机轧辊孔型设计方法的研究

针对钢管张力减径机的轧辊孔型设计方法进行研究,建立了传统孔型、椭圆孔型以及圆孔型三种轧辊孔型设计的数学模型,采用面向对象的程序设计方法,用V isual Basic6.0作为集成开发环境,采用模块结构进行程序设计,传统孔型设计方法以减径率为依据来分配变形量,在孔型设计过程中不考虑壁厚的影响,椭圆孔型设计和圆孔型设计方法以延伸率为依据分配变形量,综合考虑壁厚和外径的影响,并进一步考虑到椭圆度曲线的调整和孔型尺寸的优化,从而设计出更加合理的轧辊孔型,为钢管生产厂家提供孔型自动设计系统。     

斜轧轧辊与轧件空间接触状态的理论分析

斜轧轧辊与轧件空间接触状态的理论分析，对于斜轧孔型设计的正确和工艺可行意义重大，借助数学手段对轧辊和轧件的空间接触状态进行了分析和讨论，得到了有意义的结论。     

高压大流量直轴式柱塞泵缸体的设计与研究

讲述了用球墨铸铁替代传统复合结构材料设计高压柱塞泵缸体。通过对K3V112高压大流量柱塞泵的计算,验证了球铁作为缸体材料的可行性。对球铁进行气体软氮化可以得到具有良好的耐磨性、耐腐蚀性、耐热性和耐热粘附性的氮化物层,大大提高了缸体的性能。通过材料替代,简化了缸体的制造工艺,大大降低了制造成本并提高了生产效率与成品率。     

Simulation of roller guide wear in a high temperature test rig

Simulation of roller guide wear in rod or wire rolling mills has been performed in a high temperature test rig where the specimen rollers are in intermittent contact with the periphery of a heated rotating steel disc.By varying the time in contact during each cycle and deliberately superimposing a sliding component on the rolling contact, three components of guide roller wear were separated and quantified. The dominant component is wear due to sliding at the contact surface during rolling, followed by the isolated contribution from absolute rolling, while wear during roller acceleration is of less importance.Surface studies and the observed linear increase in wear vs. number of test cycles together with the linear increase in wear rate with normal force clearly show that abrasion by disc oxides is the dominant wear mechanism at elevated temperatures. The influence of disc temperature on the operating wear mechanisms as well as the resulting wear are also evaluated.A quantitative classification of four guide roller materials, a high chromium tool steel, two grades of high chromium cast iron and a cermet, has also been made. The hard cermet, containing about 50 vol.% titanium carbides, proved to be the outstanding material in roller guide applications.     

MPS（MBF）型中速磨煤机用高铬白口铸铁磨辊的研制

在分析ＭＰＳ（ＭＢＦ）型中速磨煤机用磨辊的工况条件和性能要求的基础上，结合国内资源，设计确定了材料的成分组成，制定了合理的铸造、热处理工艺，成功地研制了适合我国煤质特点的高铬白口铸铁磨辊．试验运行结果表明，同样工况条件下，所研制的高铬白口铸铁磨辊的耐磨寿命比进口镍硬Ｎ＃铸铁提高５０％以上，且成本降低，经济效益十分可观．     

Microstructure and erosion resistance enhancement of nodular cast iron by laser melting

The surface of nodular graphite cast iron samples was melted by 50% overlapping passes from a 3 kW CW CO₂ laser. The objective was to modify the microstructure and improve the hardness and erosion resistance of the surface. The results showed that laser melting led to complete dissolution of the graphite nodules which on solidifying created an inter-dendritic network of ledeburite eutectic with a very fine structure, good homogeneity, and high hardness. Sand particle erosion experiments were carried out at impingement angles of 30°, 60°, and 90° using angular particles of size between 300 and 600 μm. The velocity of the sand particles was 50 m/s, which was controlled by the gas pressure and measured by the double-disc method. The erosion resistance of the laser treated nodular cast iron was 110 times greater than the untreated material. The erosion mechanism of the untreated nodular cast iron under normal and oblique angles was by severe plastic deformation and ploughing; whilst the mechanism for the treated specimens was by fatigue cracking. The improvements of erosion resistance after laser treatment were considered due to the very fine structure, high micro hardness (650 Hv0.1) with the resistance to plastic flow and to the dissolution of the graphite nodules.     

基于激光再制造技术的发动机曲轴修复技术研究

介绍了激光再制造技术的原理、方法及其在球墨铸铁曲轴修复中的具体应用,通过对再制造发动机曲轴的具体方法研究,找出适合球墨铸铁曲轴修复的再制造工艺,并且研究了曲轴修复后涂层的组织和性能、摩擦磨损性能,结果表明,通过适当的再制造方法对曲轴进行修复,可以得到满意的制造表层组织和性能,有效延长曲轴的使用寿命。     

MINIMUM QUANTITY LUBRICATION (MQL) APPLICATIONS IN AUTOMOTIVE POWER-TRAIN MACHINING

ABSTRACT

Minimum Quantity Lubrication (MQL) is a near-dry machining method that may be applied to reduce coolant usage in operations such as drilling, which cannot be performed completely dry. Although significant research has been reported on MQL, relatively little information on production applications and experience has appeared in the technical literature. The most common high-volume production application for MQL is cross and oil hole drilling on steel crankshafts. This paper reviews MQL test results for deep hole drilling of forged steel and cast nodular iron under conditions similar to crankshaft oil hole drilling. The results show that MQL can yield tool life equivalent to gun drills at higher penetration rates under these conditions. This result is consistent with production experience with steel crankshafts, and shows that MQL may also be useful for cross and oil hole drilling of cast crankshafts. Limited test and production data for MQL machining of aluminum prismatics is also described. Significant areas for future research and development, including chip management, air quality, capability and robustness, and cost are also discussed.     

MINIMUM QUANTITY LUBRICATION (MQL) APPLICATIONS IN AUTOMOTIVE POWER-TRAIN MACHINING

Minimum Quantity Lubrication (MQL) is a near-dry machining method that may be applied to reduce coolant usage in operations such as drilling, which cannot be performed completely dry. Although significant research has been reported on MQL, relatively little information on production applications and experience has appeared in the technical literature. The most common high-volume production application for MQL is cross and oil hole drilling on steel crankshafts. This paper reviews MQL test results for deep hole drilling of forged steel and cast nodular iron under conditions similar to crankshaft oil hole drilling. The results show that MQL can yield tool life equivalent to gun drills at higher penetration rates under these conditions. This result is consistent with production experience with steel crankshafts, and shows that MQL may also be useful for cross and oil hole drilling of cast crankshafts. Limited test and production data for MQL machining of aluminum prismatics is also described. Significant areas for future research and development, including chip management, air quality, capability and robustness, and cost are also discussed.     

中小壳体类冲天炉铸态球墨铸铁的铁水控制

由于球铁的基体组织、石墨形态、机械性能与化学成分有极其密切的关系,故此对化学成分进行精心的设计和选择;对铸铁熔炼、球化处理及铸造缺陷的防止进行有效的控制。     

薄带铸轧工艺参数的分析和动态模拟

在建立洁净器区薄带坯凝固传热数学模型的基础上，通过计算机分析并动态模拟了铸轧过程中几个重要的工艺参数之间的关系及相互影响，分别模拟和分析了实现稳定铸轧所需的工艺参数范围，包括铸轧速度、浇注温度、熔池深度、铸轧压力、铸轧辊温度、冷却水流量及冷却水温度等重要参数，从理论上解决了铸轧奥氏体不锈钢薄带坯表面质量的关键技术问题，该方法对实际生产具有极其重要的应用价值。