变壁厚筒形构件辊挤成形过程数值模拟

为解决变壁厚筒体构件制造过程材料利用率低、机加工时长等问题,提出一种辊挤成形工艺。该工艺通过3个被动旋转辊轮的辊压作用实现坯料的塑性变形。借助Deform-3D软件建立变壁厚筒形构件辊挤成形热力耦合刚黏塑性有限元模型,对辊挤过程进行数值模拟,获得了辊挤过程中载荷-行程曲线、等效应力与应变场以及温度场的分布规律。研究了工艺参数对成形构件变形均匀性的影响。结果表明:工件变形的不均匀性随着辊挤速度和摩擦因数的增大而增大,随变形温度的升高而减小。     

Analysis on the joint tensile strength and fractography of TiNi shape memory alloy precise pulse resistance butt welding

This paper studies mechanical property and fiactography of the welded joints obtained in different welding parameters such as welding heat and welding press wlth/without gas shield in TiNi shape memory alloy precise pulse resistancebutt welding using tensile stength test, XRD, SEM and TEM measures. The optimum welding parameters obtaining high tensile strength welded joint are SOL On the condition of welding press magneting current 2 A and welding heat 75%, the joint strength is the highest. This is important for to study other properties of TiNi shape memory alloy further. The experimental results state that argon gas shield haze different effects on different welding parameters, less on welding press,but great on welding heat. But excessive welding press and welding heat have great effects on joint tensile strength. Too high welding heat can produce the new intermetallic compound, this intermetallic compound lead to dislocation density to increase and form the potential crack initiation, which can easily make the flint fracture under stress effect and decrease the shape memory ratio of joint for high density dislocation groups existing in the twinned martensite.     

微型电池组的单面点焊

微型电池组是某电子快门照像机的直流电源,由4只钮扣式锌银单体电池组组成。为减小功耗和提高可靠性,设计上要求用点焊进行串联装配。单面点焊原理钮扣式锌银单体电池不能直接用点焊方法进行串联装配。为此,在各单体电池之间添加一“工艺假壳”     

无氧铜丝贮能对焊钼杆的研究

钼杆与无氧铜丝可用贮能对焊的方法直接焊接起来。在采用强迫成形模式下,接头质量稳定,其机械性能及电性能均优于国内目前所采用的银钎焊接头。通过金相、扫描电镜分析,本文较细致的分析了该固相连接的形成机理。     

弹簧钢点焊缺陷及工艺措施

分析了弹簧钢电阻电焊接头常见的缺陷类型、形貌、成因及危害，提出了通过采用增大电极压力，调制焊接电流脉冲和随机多脉冲回火热处理等工艺措施可获得优质点焊接头，为钢质弹性件的以焊代铆提供了依据     

汽轮机带冠叶片阻尼振动特性的有限元分析

根据汽轮机叶片外形特点,在3D建模软件Solidworks中建立Z型叶冠单叶、成组叶片及整圈叶片的实体模型,通过ALGOR软件的机械运动仿真（ MES ）功能,计算带冠叶片组在不同冠间间隙、不同激励频率和幅值下的碰摩减振规律特性,并对所得结果进行分析。结果表明：通过冠间相互碰摩可有效减小叶片振动,当冠间间隙介于0．2 mm到0．5 mm之间时,碰摩减振效果最好;外部激振力对旋转产生的动应力影响较小,在特定的间隙值下,随激振力的变化叶片应力峰值变化较小。这些结论对汽轮机末级叶片的设计有重要的指导意义。     

Parameter selecting and quality predicting of spot welding based on artificial neural networks

This paper proposes a procedure for using artificial neural networks (ANN) in spot welding, and estabishesspot wilding parameter selecting ANN systems and sopt welding joint quality predicting ANN systems.It has been provedthat the ANN systems have high prediction precision ,providing a new way of parameter selecting and quality predicting in spot welding.     

基于热加工图的深盲孔筒体热冲压工艺优化

针对厚壁、深盲孔筒体传统生产过程壁厚差较大造成材料利用率较低、生产成本高等问题,以降低承载载荷,减小壁厚差为目标,通过热加工图及有限元数值模拟对热冲压工艺进行优化.开展热模拟试验获取50SiMnVB真应力-应变曲线,建立热加工图,确定工艺参数选择范围;有限元数值模拟,以冲头速度、始锻温度、摩擦因数为参变量,以最小成形力为目标,进一步对工艺参数优化,进行验证.结果表明:冲头速度为50 mm/s、始锻温度为1150℃、摩擦因数为0.3是最佳工艺参数;用该工艺参数制备的20件构件壁厚差均小于1 mm,证明优化工艺有效降低成形载荷、减少壁厚差、提高利用率.