火焰表面淬火技术在压力加工模具中的应用

一般认为压力加工模具使用火焰表面淬火,适用于对试验模具及小批量生产用模具进行简易淬火。但这里介绍的是火焰表面淬火在批量压力模具中的应用。该方法简单又方便,对合适的钢种进行火焰淬火的性能,与整体加热后淬火的性能相当,其优点很多,在生产实际中应用,可大大提高企业经济效益。     

用DF—S油对钢球进行马氏体等温淬火

采用DF -S油对轴承零件进行马氏体等温淬火试验 ,证明该淬火油可以显著降低变形和应力 ,提高钢球的压碎载荷及轴承的使用寿命。附图 3幅 ,表 3个。     

电铲大模数齿轮轴中频沿齿廓硬化

通过对大模数齿轮轴试验件进行的中频沿齿廓硬化的工艺试验,得到了理想的硬化层分布以及淬硬层深度和表面硬度,强化了齿根部分,提高了接触疲劳强度和弯曲疲劳强度,延长了重载齿轮轴的使用寿命。     

电铲上下环轨的热处理

介绍电铲上下环形轨道的热水-空气间歇冷却的淬火，讨论环形轨道在热水-空气介质中冷却的特性和实际冷却效果。     

挖掘机回转平台及三角架典型工况的有限元分析

采用有限元分析方法,建立了挖掘机平台结构的三种最危险工况下的有限元模型,分析了平台及三角架的强度和刚度,找出结构的薄弱环节是三角架的刚度偏弱,以及平台与三角架连接的部分出现应力集中的现象。这为进一步优化结构、改进设计提供了依据。     

工艺参数对45钢大电流电接触表面淬火的影响

以45钢为试验材料,研究工艺参数对45钢大电流电接触表面淬火的影响。观察分析淬火层的金相组织,并测量其厚度和硬度分布。结果表明,电接触表面淬火后的淬火层由硬化区和过渡区组成,硬化区为均匀细小的条状马氏体,过渡区为马氏体、珠光体和铁素体的混合组织。工作电流I=17kA、接触压力F=600～800N、工件转速Vr=0.5～0.75r/min时,淬火层厚度为0.78mm,硬化区硬度可达780HV0.1左右。当电参数一定,其他工艺参数改变时,工件表面硬度与淬火层厚度基本不受影响。但经过新型电接触表面淬火处理后,工件表面粗糙度降低,由Ra1.412μm下降至Ra0.732μm。     

Upsetting of pipe blank on a mandrel

A theory of the upsetting of a pipe blank on a mandrel is developed for the first time. Formulas for the effective design of upsetting operations are presented. The high accuracy of the formulas is confirmed by comparison with experimental data.     

电铲斗唇铸件砂铸模具的三维设计与快速制作

采用Pro/ENGINEER软件进行斗唇铸件砂型铸造模具的三维设计,借助三维复合建模技术的可视性、可检测性及可分析性,解决了传统二维设计中出现的疑难问题.并运用CNC快速手板技术取代传统的手工木模工艺,进行砂型模具的快速制作,解决了某厂早期生产的斗唇铸件的质量问题.结果表明,这种砂型模具的设计和制作工艺具有周期短、砂型...     

Toward autonomous mining: design and development of an unmanned electric shovel via point cloud-based optimal trajectory planning

With the proposal of intelligent mines, unmanned mining has become a research hotspot in recent years. In the field of autonomous excavation, environmental perception and excavation trajectory planning are two key issues because they have considerable influences on operation performance. In this study, an unmanned electric shovel (UES) is developed, and key robotization processes consisting of environment modeling and optimal excavation trajectory planning are presented. Initially, the point cloud of the material surface is collected and reconstructed by polynomial response surface (PRS) method. Then, by establishing the dynamical model of the UES, a point to point (PTP) excavation trajectory planning method is developed to improve both the mining efficiency and fill factor and to reduce the energy consumption. Based on optimal trajectory command, the UES performs autonomous excavation. The experimental results show that the proposed surface reconstruction method can accurately represent the material surface. On the basis of reconstructed surface, the PTP trajectory planning method rapidly obtains a reasonable mining trajectory with high fill factor and mining efficiency. Compared with the common excavation trajectory planning approaches, the proposed method tends to be more capable in terms of mining time and energy consumption, ensuring high-performance excavation of the UES in practical mining environment.     

振动清雪铲静动态强度分析

振动清雪铲可以把压实的冰雪振碎、抛扬至路边。当遇到障碍物时,清雪铲可以自动越障。文中对清雪铲进行受力分析,算出了各力的大小。以受力分析结果为基础,利用数值模拟的方法从静态、动态两个方面分别对清雪铲的强度进行分析,得到了清雪铲在静态和动态时的应力薄弱点,为进一步优化振动清雪铲提供理论依据。     

挖掘机臂杆长度的运动学优化

机械的运动优化应先于动力优化实施,但运动优化目标函数难以确定,因此应用较少,挖掘机是一种仿生工程机械,工作对铲斗应能在工作空间中沿任意路径迅速移动,基于矩阵奇异值分解建立的,运动能力准则可以较准确地衡量护斗参考点沿任意方向快速运动的能力,并由此得到挖掘机动臂和斗杆的最优长度比。