柴油机增压后机体的改进设计

利用有限元分析技术对某机型柴油机增压后的机体、缸盖、曲轴、主轴承盖、缸套等柴油机主要零部件的组合部件进行了结构强度和刚度分析。根据分析结果对薄弱部位作了改进设计,并对改进后的设计进行了效果评估,结果表明,改进后的机体取得了预期的效果。     

铝合金发动机缸盖铸造工艺的计算机模拟分析

在对铝合金发动机缸盖进行工艺分析的基础上,制定了3组浇注方案,分别为缝隙式顶冒口补缩浇注系统、顶冒口直接浇注系统、半开放式半包围型横浇道浇注系统.通过使用铸造数值模拟软件对金属液的充型和凝固过程进行数值模拟,认为缝隙式顶冒口补缩浇注系统为最优方案.确定了缸盖的优化工艺参数:模具预热温度为400℃,浇注温度为720℃.在该组优化的工艺参数下,通过对金属液的充型和凝固过程的动态观察,预测了充型时间、凝固时间和可能存在的缩松、缩孔及气孔缺陷的分布与体积分数.     

大型宽厚板坯锻造工艺的探索

本文介绍了二重水压机车间仅用现有的设备、工装锻造最大达 6 0 0 0 mm×80 0 0 mm,厚度在 2 0 0 mm～ 5 0 0 mm板坯的工艺。其独特的筒体展伸工艺及体外锻造工艺开拓了小设备干大件的新路子 ,可供锻造行业的同仁们参考     

关于内燃机缸套活塞环磨合过程的数学模型

从混合润滑和磨合动力学的角度出发，以表面粗糙度和磨损率为状态参量，建立一个关于内燃机缸套、活塞环摩擦学系统磨合过程的数学模型，分析了影响磨合过程的各种参数对磨合的影响，为磨合过程的动态仿真提供了基于润滑的表面形貌分析的理论依据     

缸套—活塞环材料在往复滑动中摩擦系数的试验研究

为了研究机车柴油机缸套活塞环材料的摩擦学性能,我们设计并制造了一台往复式摩擦磨损试验机。该试验机可在一定范围内实行载荷、速度、润滑量的单因素控制,并可同时定性和定量的显示运动中的摩擦力大小。我们利用该试验机对美国GE公司采用的软氮化铸铁缸套—表面镀铬铸铁活塞环材料进行了摩擦学性能的试验研究,得出了该配对副在往复滑动中摩擦系数随载荷和速度变化的关系曲线。     

Optimising the T6 heat treatment for gravity cast AlSi7MgCu0.5 alloy V8 cylinder heads

Alternatives to the Standard T6 heat treatment that relied on a 5-h solution heat treatment at 490 °C were investigated in effort to reduce the heat treatment cycle time for the manufacture of AlSi7MgCu0.5 alloy V8 cylinder heads without sacrificing the mechanical properties while providing extra capacity in the heat treatment plant. The optimum T6 heat treatment process was identified to be a SHT at 545 °C for 1 h followed by ageing treatment at 180 °C for 3 h. Mechanical properties of the cylinder heads thus manufactured were markedly superior while the total heat treatment duration was reduced by 2.5 h with respect to the Standard heat treatment. This implied a capacity increase of %61 and rendered the undertaking of a major customer order possible.     

新型集成电气伺服坐标气缸的研究及其应用

本文研究的是集驱动机构、位移传感器、控制阀及控制连接为一体的新型伺服气缸,对气缸的综合性能,特别是气缸的摩擦力进行了深入的研究,可为高性能气动伺服系统提供优质的气动集成元件,大大缩短了气动伺服系统的设计周期。     

关于圆柱壳轴向缓冲和吸能特性的研究

圆柱壳可以做高速碰撞情况下的缓冲吸能装置,对其力学性能、吸能特性、缓冲特性进行了分析,这些特性随着圆柱壳的半径、壁厚的变化而变化。安全防护结构的吸能与缓冲的要求可以通过调整元件的上述因素达到。     

Annular axisymmetric stagnation flow on a moving cylinder

Fluid is injected from a fixed outer cylindrical casing onto an inner moving cylindrical rod. Using similarity transform, the Navier-Stokes equations reduce to a set of nonlinear ordinary differential equations, which are integrated numerically. Asymptotic solutions for large and small cross-flow Reynolds numbers and small gap widths are also found. Drag, torque and heat transfer on the moving rod are determined. The problem is particularly important in pressure-lubricated bearings.     

Risks and safety level of composite cylinders

The increasing amount of composite transport systems for hydrogen leads to new and therefore unknown potential hazards for general public. Due to lack of experience, risks of new technologies tend to be rated higher than existing familiar applications. An approach for probabilistic safety assessment of technologies or products requires the definition of minimal acceptable reliability levels. This ensures that the probability of a critical failure with a certain consequence is limited to an acceptable risk. But what is the acceptable risk and which risk results from specific probabilities of occurrence and consequences? This is always a very complex question. The following example is based on a probabilistic approach for safety assessment of composite cylinders developed at the BAM (Federal Institute for Materials Research and Testing).