开关阀流量特性实验中液阻和液容的设计研究

本文介绍了“液阻、液容对开关阀组流量特性的影响”项目中实验研究的液压系统工作原理,说明了用于实验的液阻、液容件的设计要点和计算方法。     

液阻在液压系统中的应用分析

本文推导出了液阻的计算公式，分析了影响液阻大小的各种因素及液阻在液压系统中的具体应用，指出液阻对液压系统的设计分析具有重要的意义。     

液气锤液压系统的数学建模及仿真研究

针对沈阳某厂40 tm液气锤的液压系统进行了改进,改用大流量插装阀集成的液压系统,并对此系统打击完成后回程的工作过程进行了分析.根据液压系统工作原理建造液气锤液压系统打击后回程过程拓扑结构流程图,应用“灰箱”建模法对液气锤液压系统动态特性建立了数学模型.基于AMEsim仿真软件建立了系统模型,并得出了仿真结果,为系统改进提供了理论依据,也为今后设计锻造设备液压系统提供理论上的补充和指导.     

基于AMESim的脐带缆液压传输特性及等效方法仿真研究

分析脐带缆液压管线传输特性,提出等效方法。应用AMESim建立脐带缆液压管线液压仿真系统,进行仿真模拟,分析仿真结果,研究脐带缆的液压传输特性,并与相似性原理下脐带缆液压传输特性参数进行相对分析,确定脐带缆液压特性参数液阻、液容、液感在液压系统中的表现形式。根据分析结果,确定脐带缆液压传输特性的等效模型的形式,确定液阻、液容、液感的具体等方式,应用AMESim仿真分析了等效方法的等效性,确定了一种脐带缆液压管线的等效模型搭建形式。仿真结果可做为脐带缆液压等效装置搭建的理论参考。     

电液集成液压系统在组合机床上的应用

本文所介绍的电液集成液压系统,主要是由电液集成块及其它元器件组成。这种系统是以液压网络为基础,将电路理论和电子学方法移植到了液压回路中。它与传统的液压系统完全不同,不用一般的液压阀,不用专用密封件,属于机—电—液一体化成套液压产品。湖北拖拉机厂已将其应用在组合机床上。     

用电学理论来研究液压技术

近年来,国内外一些学者曾试图将电学理论引入到液压技术中来,以促进液压技术的发展,但因液压放大器的问题没有从理论上得到解决,所以这项工作一直停留在液阻、液容、液感的概念和公式的水平上。本文作者对此进行了研究,希望这一理论的推进能导致液压系统设计理论的更新,并创造出新型的液阻、液容等元件,使液压技术能够得到更广阔的应用前景。目前,作者用液阻、液容、液感和柱阀理论来计算和分析液压回路能得到目前一般的方法所得的结果相同,并进行了实例设计。本文将分五期发表,望广大读者提出宝贵意见。     

热卷箱液压系统的改进及优化研究

介绍热卷箱液压系统的基本工作原理以及设计特点,根据现场实际应用情况,提出系统在使用过程中出现系统扩能而冷却系统未改进、“净”环不净、PLC逻辑控制不合理、泵卸油不畅导致系统发热、系统的设计缺陷和元器件的不合理选择导致系统不能正常工作等问题,提出改进循环冷却系统、增设进水过滤器、改进PLC逻辑控制等措施改进系统发热,修正液压回路、重新选择液压元器件等优化液压回路,取得较好的效果,为今后类似设备的设计、安装和维护管理提供借鉴。     

如何提高造型线液压系统的可靠性

对提高造型线液压系统的可靠性,在设计、元器件选择、生产管理等方面提出了作者的一些建议.     

采煤机牵引部液压系统设计

牵引部液压系统作为采煤机的重要组成部分,其性能的好坏不仅影响采煤机牵引部的使用寿命,更关系到采煤机的工作效果,影响采煤机的作业效率。完成了牵引部液压系统的设计,绘制了系统原理图,并从高压保护、超速与差速防滑保护、低压欠压保护和过零保护4个方面完成了对牵引部液压系统的保护设计,在分析、计算的基础上,确定了液压系统主要元器件的参数,并完成了元器件的选型,为采煤机牵引部液压系统设计提供了技术依据。     

基于SimHydraulics的兆瓦级风机液压型变桨系统仿真

基于MATLAB/SimHydraulics工具箱,对兆瓦级风机的液压型变桨系统进行了仿真研究.借助SimHydraulics工具箱内建的液压元器件模型,可以直接对变桨系统的液压原理图进行建模与仿真.仿真结果表明:利用SimHydraulics工具箱对兆瓦级风机变桨系统进行仿真研究的可行性,为进一步对风力发电机组全工况仿真提供了保证.     

球形液压滤波器滤波机理的研究

本文通过液压球形滤波器机理的分析，推导出液压滤波器的数学通用模型。认为在建立滤波器理论模型时不能忽略滤波器的液阻影响。     

流体调制技术及其在流体伺服控制中的应用

分析和介绍了流体调制技术的原理、特点及其在流体伺服控制中的应用。     

石墨流态粒子炉微机实时控制系统

本文论述了采用神经网络方法对石墨流态粒子炉进行实时控制的系统。研究结果表明,与采用单一PID系统相比较,神经网络法实时控制系统能取得更好的控制效果     

A study of the convection heat transfer coefficients of grinding fluids

By using hydrodynamic and thermal modelling, the variation of the convection heat transfer coefficient (CHTC) of the process fluids within the grinding zone has been investigated. Experimental measurements of CHTC for different grinding fluids have been undertaken and show that the CHTC depends on the grinding wheel speed and the fluid film thickness within the contact zone. The film thickness is determined by grinding wheel speed, porosity, grain size, fluid type, flow rate and nozzle size. The CHTC values are compared for a wide range of grinding regimes, including high efficiency deep grinding (HEDG), creep feed and finish grinding.     

Investigation on cooling efficiency of grinding fluids in deep grinding

The cooling efficiency of grinding fluids in deep grinding, at different material removal rates and grinding speeds, has been investigated. Two ‘inverse’ methods have been proposed to determine the level of convective heat transfer coefficients of grinding fluids, by matching the theoretical and experimental grinding fluid burn-out thresholds or matching the theoretical and measured grinding temperatures. Instead of using a constant chip melting temperature to estimate the energy partition to the grinding chips, the chip temperature and chip energy were calculated using the newly developed approach considering the variation of chip size, deformation and heat transfer at the abrasive/work interface. The variation of grinding heat taken away by the process fluids and grinding chips under different process parameters has been calculated, which shows the importance of cooling effects by the grinding fluids and the transition of thermal characteristics of deep grinding from cooling dominant to ‘dry’ grinding regime, where a large percentage of grinding heat is taken away by the grinding chips.     

Tribological Characteristics and Cutting Performance of Lubricant Esters for Semi-dry Machining

In semi-dry machining, such as minimal quantity lubrication (MQL) machining, a very small amount of a lubricant plays an Important role to achieve a successful operation. This study investigates the tribological behavior of lubricants for semi-dry application in connection with their cutting performance. In MQL turning, synthetic biodegradable esters are superior to a vegetable oil and provide the satisfactory cutting performance compared with a conventional cutting fluid of flood supply. Their tribological action is further evaluated with the aid of tool surface analysis and the adsorption characteristics of a model ester are fundamentally examined using a controlled atmosphere machining apparatus.     

Development of Gel Structured Electrorheological Fluids and their Application for the Precision Clamping Mechanism of Aerostatic Sliders

Electrorheological fluids (ERF) are functional fluids whose viscoelastic property varies according to the intensity of the applied electric field. The disadvantages of ERF are the sedimentation of ER particles and the requirement of a seal mechanism. In order to solve these problems, gel structured electrorheological fluids (ERG) are developed in this study. The basic characteristics of the ERG film are experimentally analyzed. The ERG is applied to the clamping mechanism of aerostatic slider. By using the ERG element, the aerostatic slider can be clamped with extremely low clamping force. The ERG clamp also serves as a variable damping element of aerostatic slider.     

铸造合金深过滤机理的研究

论述了铸造合金的液态结构、表面张力、流动产生的扰动以及真空度对铸造合金深过滤的影响，从流体力学的角度提出了过滤器设计的基本要求．     

Optimisation of fluid application in grinding

This paper addresses the quantity of fluid required for grinding and the method of application. Results from this research suggest that supply flowrate needs to be 4 times the achievable ‘useful’ flowrate. Extra flowrate is wasted. It is shown that jet velocity and jet flowrate can be separately specified. Improved system design allows ‘actual’ useful flowrate to approach ‘achievable’ useful flowrate. Achievable useful flowrate depends on wheel porosity and wheel speed whereas actual useful flowrate depends on nozzle position, design, flowrate and velocity. Experimental methods are complemented by computational fluid dynamics (CFD) simulations.     

Effectiveness and resolution of tests for evaluating the performance of cutting fluids in machining aerospace alloys

The paper discusses effectiveness and resolution of five cutting tests (turning, milling, drilling, tapping, VIPER grinding) and their quality output measures used in a multi-task procedure for evaluating the performance of cutting fluids when machining aerospace materials. The evaluation takes into account the following process output measures: tool wear, cutting forces, torque, spindle power, geometrical accuracy, texture and integrity of workpiece surface. Using statistics, through calculation of the Hellinger distance, the resolution given by experimental data was evaluated and a comparison of robustness in ranking the performance of cutting fluids based on different output measures and cutting tests is presented.