共查询到19条相似文献,搜索用时 189 毫秒
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为了判定乳化液泵卸载阀主阀的失效机理,根据卸载阀使用时的实际工况,搭建了卸载阀液压模型,对主阀启闭过程中,阀芯速度、位移以及阀口压力、流量进行了研究,发现主阀在开启过程中阀芯震颤严重,压力流量波动范围大,较闭合过程而言,对主阀的失效影响更大。经过理论计算,得出主阀开启后稳态时的阀芯开口量,并对主阀稳态及瞬态开启过程进行了分析,得出了各状态下主阀压力、速度、湍动能以及流体轨迹的变化情况,着重对主阀a/b/c处损伤原因进行了判定分析。结果表明,阀芯a处损伤主要因瞬态气蚀、涡流造成,b处损伤主要因瞬态及稳态流体涡流造成,阀套c处损伤主要因瞬态及稳态气蚀造成。 相似文献
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2.盐浴软氮化盐浴软氮化虽然能获得良好的性能、缩短处理时间,但是由于采用氰化盐类存在严重的公害问题,限制了这种工艺的应用。近年来,盐浴软氮化一方面从废液处理进行研究寻找破毒的处理方法,另一方面研究无毒盐浴软氮化途径、得到了一些进展,发展了新工艺。(1)无公害盐浴软氮化在30届国际热处理讨论会上 B·Finnern 和H·kunst 提出了一种无公害盐浴软氮化工艺。这种工艺根据氰化盐的反应式: 相似文献
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溢流阀是液压系统中重要元件之一,它具有限压、保压及稳 压的作用(分为先导式溢流阀和直动式溢流阀两类)。以先导式溢流阀为例,其工作原理如图1所示:该阀由先导阀3与主阀1组成,系统压力作用于主阀1与先导阀3上,当先导阀3未打开时,主阀1左右两方压力平衡,弹簧2将主阀1压在右端位置,使阀口关闭,当压力P增大到使先导阀3打开时,液流经过阻尼孔5、先导阀3回油箱,由于阻尼孔作用使主阀1右端压力大于左端压力,主阀1在压差作用下向左移动,打开阀口,实现溢流;当主阀1左右两方压力平衡,则阀口大小确定。这样,领先… 相似文献
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P. Hubbard D. G. McCulloch E. D. Doyle S. J. Dowey J. N. Georges 《BHM Berg- und Hüttenm?nnische Monatshefte》2006,151(11):441-445
Active Screen Plasma Nitriding (ASPN) is a novel plasma based nitriding process which challenges many of the existing hypotheses concerning mass transfer in plasma nitriding and, in turn, questions the influence of substrate bias during nitriding. In this study, a Field Emission Gun Scanning Electron Microscope analysis was used to investigate material transfer from the active screen. The results demonstrate that material transfer and deposition, in the form of nano-particles, take place from the active screen to parts that are in a direct line of sight of the active screen. The nano-particle distribution is significantly influenced by the type of active screen material used and the application of substrate bias. However, the suggestion that the mechanism of mass transfer in ASPN is directly related to sputtering of material from the active screen is questioned by the observation that AISI H13 steel samples treated in a non line of sight position in the ASPN chamber showed a significantly higher nitriding response than AISI H13 samples treated in direct line of sight of the active screen. 相似文献
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Operating principle of water three-way valve with high flow for individual hydraulic prop in coal was presented in this paper, its strict and precise mathematical model was established, its flow field was simulated numerically by software Fluent, and its dynamic characteristics were analyzed during the work process such as raising leg, loading and overflow, the influence of the related parameters on high-flow water three-way valve was determined. The results as follows: during the raising leg stage and early raising leg stage, when the damping ratio increases, the overshoot of system decreases and the setting time reduces, and the dynamic response performance has a significant improvement. During the loading stage and the overflow stage, the pressure in plunger chamber of single hydraulic prop, the output flow and the displacement of the high-flow water three-way valve decrease with the decreasing of the external load. The spring stiffness of the safety valve directs the flow and the spool’s displacement of the safety valve, and it can be used to control the high-flow three-way valve’s sensitivity. 相似文献
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P. Hubbard S. J. Dowey E. D. Doyle D. G. McCulloch 《BHM Berg- und Hüttenm?nnische Monatshefte》2006,151(3):118-122
The effect of a substrate bias and prenitride plasma etching on the nitriding response of four steel substrates is investigated in a two factor two level full factorial experimental design. The steels investigated were P20 (M200, Plastic mould steel), H13 (W302, Hot-work tool steel, as received), 4140 (Preheat treated nitriding steel) and 1020 (CS1020, Bright mild steel). The nitriding response was determined from surface and cross-sectional hardness measurements. Nitrogen depth profile measurements were obtained using Glow Discharge Optical Emission Spectroscopy. — Considering the main effects, the results show that without worktable bias during the nitriding step there is effectively little or no nitriding response in most of the materials. The prenitride plasma etch did not produce a significant surface hardness response in all steels except H13, where a prior etch substantially increased surface hardness and influenced the hardness depth profile. The bias significantly increased the nitrogen wt%. The plasma etch also influenced the near surface nitrogen wt% concentrations, however, the practical implications of this require further investigation. 相似文献
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利用QPQ技术对F690海工钢进行盐浴复合强化处理,考察了碳氮共渗温度和时间对F690钢渗层组织、相结构及硬度、腐蚀磨损性能的影响。结果表明:经过QPQ处理后,F690钢表面形成由Fe3O4氧化层、Fe2C/Fe2N化合物层及扩散层组成的渗层,且渗层组织平整均匀。随着QPQ处理温度升高和时间延长,渗层厚度增加,渗层硬度均呈先增大而后减小的变化规律;当共渗温度为570 ℃、时间为60 min时,F690钢的渗层硬度达854HV,较F690钢硬度提高1.7倍。与F690钢相比,3.5%NaCl介质下渗层的自腐蚀电流密度降低了一个数量级,腐蚀速率降低了86.71%,摩擦系数下降约12%,磨损率显著降低。 相似文献
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针对过卷液压缸缓冲吸收提升箕斗过卷冲击所产生的压力波动问题,通过增加节流阀,接通过卷液压缸有杆腔和无杆腔,对提升机过卷液压缓冲系统进行了优化设计,对优化后的提升机过卷液压缓冲系统工作原理开展了研究,利用AMESIM对过卷液压缓冲系统仿真模型进行了搭建,对比分析了优化前后过卷液压缸有杆腔压力、箕斗位移、箕斗速度的动态性能曲线,仿真研究了节流阀通径对过卷液压缓冲系统的影响规律,研究结果表明:优化后的提升机过卷液压缓冲系统缓冲性能得到提升,节流阀能吸收过卷液压缸有杆腔压力波动,节流阀通径对过卷液压缸活塞复位具有较大影响,当通径为9mm时,过卷液压缓冲系统性能较好,过卷装置动力学特性较好。 相似文献
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