锥面砂轮磨齿机磨齿时磨削点速度的变化规律

分析了锥面砂轮磨齿机磨齿时磨削点速度的变化规律 ,并推导了磨削点速度的计算公式。     

Experimental Investigation of Lubrication Film Starvation of Polyalphaolefin Oil at High Speeds

The lubrication behavior of starved elastohydrodynamic contacts at high speeds was investigated in this study. A new ball-on-disc test rig with the ability to measure traction force at high speeds up to 100 m/s and lubrication film thickness at speeds up to 42 m/s was built. The relative optical interference intensity technique was used to measure the film thickness. The experimental results show that the film thickness decreased rapidly and asymmetrically when the speed exceeded a critical speed under the starved lubrication condition. Starvation is governed by the amount of lubricant available both in the inlet region and on the side of the oil reservoir. The shape of the oil reservoir becomes asymmetric and the amount of oil gradually reduces against the speed at high speeds because of the centrifugal effects, under which the oil on the outer side of the oil reservoir will be thrown away and the oil on the inner side of the oil reservoir will be compressed. The balance of oil supply and oil loss due to centrifugal force determines the starvation behavior.     

砂轮振动对磨削区时变润滑效应的影响

为研究砂轮振动对磨削区压力、膜厚及温度的影响,建立考虑时变效应的砂轮振动磨削的润滑模型,分析陶瓷结合剂CBN砂轮磨削45~#钢的过程中的最大压力、最小膜厚和最大温度随振动的幅值、频率及砂轮速度的变化情况。结果表明:考虑砂轮振动的时变效应时,不同瞬时下的压力及膜厚变化较大;随砂轮振幅和频率的增大,当砂轮振动到最低点时最大压力及最大温度增大,最小膜厚减小,而振动到最高点时则相反;时变效应使最大压力、最小膜厚与最大温度出现了滞后现象;当砂轮速度增大时,最大压力减小、最小膜厚增大,这有利于润滑且能减少磨粒磨损,但是最大温度增大容易产生磨削烧伤和热变形,影响工件磨削后的表面质量,所以应据此选择合适的砂轮速度。     

杯形砂轮磨削高硬度球面砂轮磨损的研究

采用分块杯形砂轮磨削高硬度球面,磨削过程中砂轮磨损不仅影响砂轮磨削性能,而且造成工件和砂轮实际接触面积不断产生变化,影响磨削力和磨削质量。为此,基于展成法磨削原理研究砂轮块磨损后的形状变化,分析了分块砂轮的磨损形式,揭示了进给过程中砂轮块磨损形状的变化规律,推导了砂轮磨损量和砂轮工件接触面积的计算公式,分析了砂轮磨损速度的变化趋势及其影响因素,试验最后研究了砂轮磨损量的变化规律,并验证了砂轮磨损量的计算模型。     

Minimum-Quantity Lubrication Systems with Additional Air Cleaning of the Grinding Wheel Surface

Russian Engineering Research - Two grinding technologies with air cleaning of the wheel surface are compared: the baseline system ensures minimum lubricant supply; the other includes additional air...     

CBN砂轮的高速、超高速磨削技术

论述了CBN砂轮的高速、超高速磨削的现状、发展趋势，提出了实现CBN砂轮高速、超高速磨削使其逐渐完善并趋于实用的关键技术。     

Friction and Wear at High Sliding Speeds

Sliding tests have been carried out using a variety of soft metal and nonmetal pins on a rotating steel disk at speeds up to 150 m/s. A new high-speed friction apparatus in which the normal force, the friction force and the friction coefficient are recorded, was used. In general, the wear rate increased drastically, and the friction coefficient decreased moderately as the sliding speed was raised, these changes being especially pronounced when pin materials of low melting temperature were used. The friction data are in good agreement with those obtained by others using the pin-on-disk geometry. However, although in many cases the interface reached the melting temperature of the lower melting sliding material, the very low friction coefficient values of under 0.05 reported by some investigators were not reached.     

高速／超高速砂轮基盘的优化分析

为了确保高速/超高速砂轮的安全性,对砂轮的受力进行了系统分析.认为砂轮工作时,砂轮的安全性主要受离心力的影响,整体式高速砂轮应以校核砂轮的抗拉强度为主,而超高速分体式砂轮应以控制基盘的径向膨胀量为主.并以ANSYS软件为辅助工具,分别对砂轮基盘的形状、材料、孔径比进行了分析和选择.最后,以最小径向膨胀量为目标函数,在200m/s的转速下,对钛合金梯形基盘的截形进行了最优化.     

垂直式超硬砂轮圆弧修整器设计与砂轮修整

针对圆弧形超硬砂轮修整难度大、修整精度低的问题,对树脂结合剂圆弧形金刚石砂轮进行了精密修整研究。设计制造了一种垂直式超硬砂轮圆弧修整器,通过修整试验研究了不同粒度的圆弧形砂轮在修整前后表面粗糙度、弧形精度、圆度、表面形貌的变化情况。砂轮修整前后对氮化硅陶瓷轴承套圈沟道进行了磨削,并测量了磨削后的轴承套圈沟形精度。研究结果表明:相比修整前,修整后砂轮表面粗糙度平均值由1.731 8μm减小至0.772 4μm,减小了55.4%;弧形精度平均值由33.604 7μm减小至8.527 6μm,减小了74.6%,修整后4个砂轮的弧形精度更加稳定,且随着砂轮粒度的减小,弧形精度略有减小趋势;砂轮圆度平均值由43.721μm减小至18.002μm,减小了58.8%,修整使大量新的磨粒露出。所设计的垂直式超硬砂轮圆弧形修整器可对圆弧砂轮进行精密修整,可改善圆弧形砂轮的弧形精度及圆度,修整后砂轮磨削的轴承套圈沟形精度得到了大幅提高。     

基于砂轮法向跟踪的回转曲面磨削研究

在回转曲面的磨削中,采取小直径平行砂轮代替圆弧砂轮的方法,保证曲面磨削点的法向始终与砂轮表面垂直,实现砂轮法向跟踪磨削.根据磨削轨迹,建立了磨削表面残留高度模型,分析了砂轮半径、工件曲率和进给速度对残留高度的影响.并进行磨削试验,得出了砂轮半径、工件曲率及进给速度对表面粗糙度的影响曲线,其变化规律与残留高度的变化规律基本一致,证明在回转曲面磨削中,可以通过控制残留高度的大小来改善磨削表面粗糙度.     

高速磨削用单层钎焊CBN砂轮及其磨削性能

针对钎焊砂轮存在的热变形导致精度降低的问题,提出基于局部加热的超高频感应钎焊工艺方法制备高速磨削用单层钎焊CBN砂轮,采用三坐标测量仪对砂轮及其钎焊前后的尺寸进行测量,最后对该砂轮高速磨削镍基高温合金磨削性能进行评价。三坐标测量结果显示,钎焊CBN砂轮基体的变形量小于16μm,在高速重负磨削镍基高温合金试验中,加工表面未见裂纹和烧伤,表面粗糙度可达Ra0.4μm,砂轮表现为正常磨耗磨损。表明超高频感应钎焊工艺制备的单层钎焊砂轮在高速磨削具有应用潜力。     

高速钢材料的粗金刚石砂轮轴向进给数控磨削机理研究

根据正交试验确定了影响高速钢材料的粗金刚石砂轮轴向进给数控磨削表面粗糙度值Rα的最主要因素是进给速度Vfo。在此基础上，进行进给速度巧单因素数控磨削实验，对数控磨削后表面粗糙度值进行了分析。分析结果表明，要用粗金刚石砂轮进行轴向精密加工，采用具有较多的磨粒数且磨粒均匀分布在轴向和周向的砂轮和采用较低的进给速度对精密加工更有利。     

金刚石砂轮切割工程陶瓷时工艺参数对砂轮寿命的影响

研究了金刚石砂轮切割工程陶瓷时各工艺参数对砂轮径向磨损量的影响 ,通过正交试验 ,发现各工艺参数对径向磨损量影响的主次顺序为 :砂轮速度—切割深度—进给速度     

在线电火花修整砂轮磨削技术

在线电火花修整砂轮磨削技术已有多方面的发展,可获得较好的砂轮表面质量,并且能实现对难加工材料的高质量、高效率加工。文中对国内外相关技术作了介绍,并就存在的问题进行了分析。     

磨削加工砂轮堵塞钝化问题的研究

磨削加工中,不仅磨粒的尺寸、形状和分布对加工过程中有影响,而且砂轮的气孔状况也起着重要的作用.往往在加工韧性金属时,出现砂轮的急剧堵塞钝化,导致砂轮寿命过早结束.     

电火花修整金刚石微粉砂轮的磨削特性

地于金属结合剂金刚石微粉砂轮来说，电火花修整法是一种高效的修整方法，本文讨论了电火花后青铜结合剂金刚石微粉砂轮磨削工程陶瓷的磨削力、磨削工件表面粗糙度特性，并同常规磨削法修整进行了比较。     

Lubrication of Solids at High Temperatures

This paper deals with recent work applicable to the problems of high-temperature lubrication carried out in the Laboratory of Physics and Chemistry of Solids, University of Cambridge, England. Three main aspects are considered (a) friction of lamellar solids, (b) lubrication from the gas phase (c) frictional properties of hard metals at high temperatures.     

Solid Film Lubrication at High Temperature

The behavior of several solid film lubricants has been experimentally established as a function of temperature. These films are formed of a suspension of lubricant particles (graphite, molybdenum disulfide) in a thermosetting resin baked onto a hard surface. The test consists of heating such a layer and continually observing the friction coefficient until failure. Sliding conditions of high unit loading and low rubbing velocity were chosen to provide a comparison between the films. They were evaluated as to the highest temperature for which the friction coefficient remained low and subsequently as to the number of load cycles sustained at temperature before an abrupt increase in friction. Results for all films were similar in that failure was caused by a breakdown of the binder rather than the lubricating particles and that the minimum friction coefficient (～ 0.03) was observed just before the film failure at temperatures as high as 1200° F.     

砂轮性能对齿轮磨削效率及磨削烧伤的影响

在齿轮磨削过程中,为提高磨削效率,降低磨齿烧伤的概率,在已知机床性能的前提下,改变不同砂轮种类进行齿轮磨削试验。通过对三种砂轮的磨削结果比较,总结出影响磨削效率的砂轮方面因素,找出适合不同材料齿轮磨削的最佳磨削砂轮种类,并在生产实践中推广使用。有效解决了磨削效率和磨削烧伤的矛盾。     

激光修整青铜金刚石砂轮的高速磨削试验研究

利用自行研制的声光调QNd：YAG激光器，对青铜金刚石砂轮进行修整试验。用光学显微镜观察修整后的砂轮表面，得到砂轮形貌随修整参数变化关系。对激光修整后的砂轮进行高速磨削试验，得出了砂轮磨削力和试件表面粗糙度随激光修整参数变化的关系。与碳化硅滚轮修整法进行对比试验，结果表明，合适的激光参数修整后，青铜结合剂金刚石砂轮对氧化钇部分稳定氧化锆材料的磨削力小于碳化硅滚轮修整。