低速轮胎试验机动力滑台动态特性分析

介绍了由伺服阀控制对称液压缸,并由位移传感器或速度传感器构成的轮胎试验机纵向往复运动液压位置及速度闭环控制系统,讲述了该系统的工作原理,建立了控制系统的数学模型,对速度和位置控制系统进行了校正,并采用了一种复合的控制策略实现了速度和位置的复合控制.提出了控制系统的SIMULINK仿真模型,给出了在阶跃信号作用下的滑台的速度的响应.     

带内螺纹的望远镜镜身注塑模具设计

分析了望远镜镜身的结构,提出了塑件成型及模具设计的关键点,设计了模具的整体结构。设计了可相对运动的组合式型芯,以增加内抽芯机构的运动空间,通过塑件推出时带动螺纹滑块的移动实现了内侧抽芯。设计了矩形型芯镶块、加工了避空结构,采用螺钉固定,解决了狭小空间安装小型芯的问题,避免了模具干涉。采用了锥面配合,提高了模具的定位精度,减小了配合件的摩擦。经生产验证,该模具生产的塑件质量满足图纸要求。     

基于流程图知识表示的工程机械液压故障诊断专家系统

根据工程机械液压系统故障诊断的特点,建立了液压故障诊断专家系统。提出了利用故障定位流程图作为专家系统诊断知识的表示方式,研究了图形化的知识库生成工具Auto Flowchart,构建了诊断知识数据库,设计了故障诊断专家系统的结构,开发了基于流程图知识表示的故障诊断专家系统。有效解决了传统专家系统知识获取困难的问题;实现了液压系统的故障定位;方便了诊断知识的维护与更新,提高了查找故障的准确率及效率。最后,以QYJ40B起重机为例进行了应用,结果表明该方法有效可行。     

导向筒挤压成形工艺及模具设计

探讨了导向筒挤压的可行性,对几种工艺方案进行了分析,选择了最优方案并制定了工艺流程,在此基础上设计了导向筒挤压模具。采用冷挤压工艺加工后,提高了零件精度和表面质量,改善了强度和韧性,减少了切削加工量,节约了原材料,提高了生产效率,也改善了零件的组织性能。     

盖板钻孔攻丝夹具设计

介绍了盖板零件的结构工艺,分析了零件上的4个螺纹孔的工艺要求,针对4个螺纹孔的加工,通过采用专用的夹具,简化了生产零件的模具结构,实现了零件产品的最终要求,保证了质量,同时也提高了效率、降低了成本。     

塑料转叶零件模具设计与制造

介绍了转叶塑件模具设计的过程.采用了点浇口形式和合理的脱模机构以及线切割慢走丝的加工方法,提高了产品的尺寸精度及其叶片间的位置精度,保证了转叶的工作平稳度,满足了产品的技术要求.     

关于熔炼Cu-Zn合金ZnO中毒的研究

分析了熔炼Cu-Zn合金造成Zn0中毒的原因,阐述了中毒的症状,提出了治疗和预防的方法和措施,杜绝了中毒事件的再发生,保证了生产的顺利进行.     

散热板成形工艺分析与模具设计

分析了散热板的成形工艺,对成形件进行了改进,介绍了一种利用回弹成形的工艺方法,设计了1副带出模斜度的柱形模具,解决了散热板成形中的难点,取得了较好的经济效益。     

插座壳体注塑模脱模机构设计

通过对某电连接器插座壳体的工艺分析,介绍了该插座壳体注塑模的整体结构及设计要点,研究了模具脱模过程,分析了脱模机构的结构特点,提出了一种较为独特的二次脱模机构,给出了活动型块一次弹顶、内侧滑块二次顶出的脱模机构,实现了塑件的顺利顶出,解决了顶出机构不易设置、脱模过程容易夹腔的问题.     

合理配置6kV供电系统补偿容量

分析了中铝兰州分公司6kV供电网络现状和运行情况。讲述了无功补偿的原理,结合实际需求,对6kV补偿系统补偿容量进行了重新计算,合理调整了补偿容量,可以减少供电网络中流过的无功功率从而降低了网络中的有功功率损耗,通过串联电抗器以消除补偿投入时产生的高次谐波的影响,降低了无功功率,改善电压质量,提高了供电质量,使其达到了供电系统功率因数的指标,为公司节电节能降低电耗工作做出了贡献。     

FATIGUE BEHAVIOUR OF M/B DUPLEX STRUCTURE IN A HIGH CARBON Cr-Mo-W STEEL

Determination was carried out of fatigue crack propagation rate of steel 65Cr5Mo3W2VSiTi(LM2)with various bainite contents and M/B duplex structure tempered at various tempera-tures.The threshold value of fatigue for each processing was estimated by experimental data.The mechanism for fatigue crack propagation of M/B duplex structure in steel LM2 seemsto be non-continuous.The calculated fatigue crack micro-propagation rates are found toagree with the experimental data.     

高碳Cr—Mo—W钢M／B复相组织疲劳行为研究

用紧凑拉伸试样测定了65Cr5Mo3W2VSiTi(LM2)钢不同贝氏体量和不同回火温度的M/B复相组织的疲劳裂纹扩展速率,根据试验数据估算了各工艺的疲劳门槛值。结果表明,LM2钢M/B复相组织的疲劳裂纹扩展属非连续扩展机制,疲劳裂纹微观扩展速率的计算值和宏观扩展速率的实测值相近     

两种钢冲击腐蚀磨损性能的对比研究

研究了在酸性铁矿石浆料及2.0J冲击功条件下,高锰钢及新型低碳高合金钢衬板的冲击腐蚀磨损性能和机制.结果表明,在相同试验条件下低碳高合金钢的冲击腐蚀磨损性能要优于高锰钢的.低碳高合金钢短时间内的冲击腐蚀磨损机制主要为显微切削,随着时间的延长,变为以浅层小块疲劳剥落为主;而高锰钢短时间内的冲击腐蚀磨损机制主要为浅层累积变形疲劳剥落和腐蚀磨损,随着时间的延长变为相对较深层的疲劳剥落和腐蚀磨损.     

IMPROVEMENT OF CARBIDE MORPHOLOGY AND MECHANICAL PROPERTIES OF Cr12MoV STEELS

1. IntroductionCr12MoV steel is used widely as an important high wear resistallt cold die steel aroundthe world[1]. It is well known that Cr12MoV steel has networked carbide in the solidification structure, which leads to the intergranular brittleness. Moreover. The networkcarbide is too stable to be changed during heat treatment even at high temperaturely]. Inthe conventional process, forging is needed to break etwork carbide into a granular form.However, partly owing to Cr12MoV steel hav…     

基于CDM法AZ31B镁合金焊接接头疲劳评定

采用临界距离法(CDM)中的点法和线法对AZ31B镁合金对接接头和横向十字接头进行疲劳评定.对两种焊接接头进行了疲劳试验,采用ANSYS有限元软件建模分析,计算出两种评定方法的局部应力参量Δσloc,拟合出相应的S-N曲线,并与疲劳试验结果进行了对比分析.结果表明,采用CDM法可以对镁合金焊接接头进行疲劳评定,其评定结果与疲劳试验结果相符合.依据应力集中大小可以有效预测疲劳断裂位置,在2×106循环次数下,两种焊接接头点法的疲劳强度分别为79.55和49.10MPa,线法的疲劳强度分别为79.01和44.38MPa.     

组织状态对循环冲击及非冲击载荷下裂纹扩展的影响

本文对10~#钢和45CrNi合金钢的几种组织状态分别进行了冲击疲劳及非冲击疲劳裂纹扩展试验,结果表明:45CrNi的组织状态对冲击疲劳裂纹扩展的影响较对非冲击疲劳的大;10~#钢的组织状态对两种载荷下的裂纹扩展基本上无影响。结合微观机制和载荷特性,讨论了组织因素对冲击、非冲击疲劳裂纹扩展的影响。     

Research about the Effect of Ultrasonic Impact on the Fatigue Properties of Cruciform Joints of 16MnR Steel

Surface impact treatment was carried out on the cruciform joint weldment of 16MnR steel by using the HJ-II-type ultrasonic impact machine.The ultrasonic impact current is 1.2 A,the impact amplitude is 30?m and ultrasonic impacting time is 30 and 60 min,respectively.Fatigue experiments were carried out for both treated specimen and un-treated specimen by using EHF-EM200K2-070-1A fatigue testing machine.The fatigue fractures were observed with the scanning electron microscope of 6360LA type and the microstructure of ultrasonic impact treating surface layer was analyzed by using high resolution transmission electron microscope of JEM-2100 type.The experimental results show that the microstructure of ultrasonic impact surface layer has been successfully nanocrystallized.The fatigue life of welded cruciform joints of 16MnR steel can be significantly improved through the ultrasonic impact treatment.The main reasons are that the ultrasonic impact treating can reduces the stress concentration in the weld toe,decrease the tensile stress,and even change to compressive stress in the weldment,the grain size in the welded joint can be refined.The longer the impact time,the greater increasing range of fatigue life will be.Compared to the sample without treatment,its fatigue life was increased 210.37%,362.48%,respectively,when the impact time was 30,60 min,respectively.     

30CrNi4Mo钢的组织和冲击疲劳性能的研究

研究了30CrNi4Mo钢不同热处理的组织和冲击疲劳性能。结果表明,30CrNi4Mo钢正火低温回火的组织由贝氏体、马氏体和残余奥氏体组成,淬火低温回火组织为回火马氏体和残余奥氏体。正火低温回火的冲击疲劳裂纹形成寿命高于淬火低温回火和淬火高温回火的冲击疲劳裂纹形成寿命,淬火高温回火的冲击疲劳总寿命高于正火及淬火低温回火热处理的冲击疲劳寿命。分析了多冲击疲劳裂纹扩展的行为,讨论了正火低温回火冲击疲劳裂纹形成寿命较长及淬火高温回火提高冲击疲劳总寿命的原因。     

轨道交通高端轴类零件用材料对比

通过对轨道交通高端轴类产品车轴用35CrMoA、EA4T、EA1N、DZ2、30CrNiMoV12钢等材质,和转轴用35CrMo、40CrNi2MoA、34CrNiMo6、30CrNiMo8钢等材质热处理后的组织性能对比,对轴类零件用材料进行了优选。车轴材料对比试验结果表明,经过热处理后30CrNiMoV12钢的强韧性远高于其他材质,冲击韧性、缺口敏感性、疲劳强度是车轴材料中综合性能最优的一种,可用于受结构尺寸限制的高强度车轴或高寒条件下使用的车轴。DZ2材料次之,EA4T钢性能接近于DZ2钢,但低温冲击性能不如DZ2钢稳定。EA1N钢整体的强度只有30CrNiMoV12钢的一半。转轴材料对比试验结果表明,经过热处理后40CrNi2MoA、34CrNiMo6、30CrNiMo8钢的强韧性较好,低温冲击性能良好且稳定,30CrNiMo8钢耐疲劳强度更好,缺口敏感性更低,适用于高强度转轴和高寒条件下应用的车轴。相比之下35CrMo钢强度略低,低温冲击性能较好,略低于其他材料且稳定性有待提高。     

The Effects of Martensite Content on the Mechanical Properties of Quenched and Tempered 0.2%C-Ni-Cr-Mo Steels

Three martensite contents (approximately 35, 50, and 100%) were obtained in a SAE8822 steel by altering the quenching media and section size. Another variation in martensite content (approximately 80 versus 97%) was achieved by quenching a SAE8622 steel in the same section size. The impact toughness and fatigue properties were determined after tempering to various levels of monotonic strength. Toughness and strength-toughness combinations improved with increased as-quenched martensite contents at all levels of as-tempered ultimate tensile strength (UTS). Even at higher levels of yield strength (YS), increased martensite contents produced higher impact energies and lower fracture appearance transition temperatures. The cyclic YS was independent of martensite content (at the same level of UTS), even though the monotonic YS increased with martensite content. When fatigue test results were compared at a tensile strength of 1240 MPa (180 ksi), actual and predicted fatigue lives in the high cycle regime increased with martensite content, but low cycle fatigue resistance was relatively unaffected. Fatigue strength and UTS were directly related, and all the quenched and tempered steels exhibited cyclic softening.