高速超高速磨削工艺及其实现技术

高速超高速磨削加工是先进制造方法的重要组成部分，集粗精加工与一身，达到可与车、铣和刨削等切削加工方法相媲美的金属磨除率，而且能实现对难磨材料的高性能加工。本文主要论述了高速超高速磨削工艺技术的特点；分析了电主轴是高速超高速磨削主轴系统的理想结构，介绍了陶瓷滚动轴承、磁浮轴承、空气静压轴承和液体动静压轴承在主轴单元中的应用；超高速砂轮主要用电镀或涂层超硬磨料(CBN、金刚石)制成，介绍了超硬磨粒的特点和砂轮的修整，分析了在高速及超高速磨床上得到广泛应用的德国Hofinann公司生产的砂轮液体式自动平衡装置；介绍了高压喷射法，空气挡板辅助截断气流法，气体内冷却法，径向射流冲击强化换热法磨削液供给系统的特点；最后介绍了直线电机进给系统和声发射智能监测系统等实现高速超高速磨削的关键技术。     

超高速点磨削力数学模型的建立与仿真

结合超高速点磨削的特点,将磨粒简化为圆锥形,建立了超高速点磨削力数学模型.通过对磨削力的Matlab仿真,分析了磨削参数和点磨削变量角α和β对磨削力的影响.结果表明:点磨削力随着砂轮线速度的增加而减小,随工件速度、磨削深度、纵向进给速度的增加而增大.点磨削力随磨削变量角α和β的增大而降低,其中,β对降低磨削力的贡献要大...     

数控快速点磨削技术的绿色特性分析

分析了数控快速点磨削(Quick-point Grinding)超高速、薄超硬磨料砂轮、点接触和连续轨迹数控成型的技术特征，以及数控快速点磨削工艺的加工性能。快速点磨削主要工艺特点是磨削力和磨削温度低、磨削比大、表面完整性和加工精度好。基于绿色制造理论，通过对快速点磨削技术的磨削机理及绿色特性的分析，提出了实现干式绿色快速点磨削的主要研究内容及方向，并结合该项新技术的发展现状，讨论了开展面向绿色制造的快速点磨削技术的理论与应用研究的重要意义。     

数控快速点磨削技术及其应用

快速点磨削（Quick-Point Grinding）是一种先进的超高速磨削技术,它集成了超高速磨削、CBN超硬磨料及CNC技术,在加工轴类零件场合具有优良的性能。介绍了快速点磨削技术的发展现状及工艺特征,分析了快速点磨削机理和材料去除机制。结果表明：砂轮的磨损机制不同于一般外圆磨削,磨削过程具有较高的绿色加工性能;通过合理控制磨削参数和磨削条件,该项技术可应用于对一些难加工材料和复杂回转表面的高质量磨削加工,由此提出了在这些领域开展应用研究的重点内容,以及推广和开发此项技术的意义。     

高效率磨粒加工技术发展及关键技术

高效率磨粒加工是先进制造方法的重要组成部分，集粗精加工与一身，达到可与车、铣和刨削等切削加工方法相媲美的金属磨除率，而且能实现对难磨材料的高性能加工。阐述了高速超高速磨削、快速点磨削、高效深切磨削、缓进给磨削、高速重负荷荒磨以及砂带磨削等高效率磨粒加工技术的国内外的发展及最新研究进展。研究了高效磨削砂轮、主轴及其轴承技术、高效率磨床、磨削液供给技术、砂轮、工件安装定位及安全防护技术以及磨削状态检测及数控技术等实现高效率磨粒加工的关键技术，分析了发展高效率磨粒加工的重要性。     

超高速磨削砂轮基体结构的多目标遗传优化

针对砂轮基体在超高速磨削状态下膨胀变形的问题,以控制砂轮基体膨胀变形和降低旋转应力为目的,对超高速磨削砂轮基体进行结构优化。在分析砂轮基体截面形状对砂轮性能影响的基础上,以直线和样条曲线为基本的构造线建立砂轮基体的参数化模型,进而实现了对砂轮基体结构的多目标遗传优化,优化后的砂轮基体在250 m/s的磨削速度下,其膨胀变形和等效应力分别降到30.827 μm和94.97 MPa,与原有砂轮相比分别降低了25.67%和6.44%。      

超高速磨削条件下的磨削液净化过滤技术

简要介绍了磨削液的一般净化过滤方法。经过比较,认为硅藻土预涂层过滤方法适合于对ＣＢＮ砂轮超高速磨削条件下的磨削条件下的磨削液进行净化过滤。讨论了预涂层过滤技术的原理及硅藻土助滤剂的特性,对过滤元件及有关参数的选择做了说明。最后介绍了一种硅藻土地滤系统。     

超高速砂轮的强度及基体优化

超高速磨削必须使用超高速砂轮。超高速砂轮基体设计是砂轮技术的关键。本文分析了超高速砂轮的结构特点，建立了基体强度计算及截形优化的数学模型，并基于实用化进行了截形的线性化拟合。从而为我国超高速砂轮的标准化设计提供了一定的依据。     

高速超高速磨削加工技术的发展

介绍了磨粒加工技术的起源与发展，分析了高速超高速磨削加工国内外的发展现状及关键技术，阐述了发展高速超高速磨削加工的重要性。     

基于有限差分模型的磨削弧区流场动压力数值分析

磨削弧区动压力对通过磨削区磨削液的有效流量、润滑和冷却作用有重要影响。本研究基于流体动压理论,建立了磨削弧区的动压力分布数学模型,将微分方程简化至近似泊松方程形式后,采用有限差分法将连续方程离散化,得出了磨削区动压力的数值解,并提出了迭代优化算法,提高了计算效率。将砂轮特性参数纳入数学模型之中,可根据砂轮材质、砂轮与工件间隙、砂轮转速等参数预报磨削弧区的磨削液动压力分布。在此理论模型基础上,进行了验证实验,证明模型的科学性。结果表明:通过输入砂轮各项参数,该模型可以快速、准确地预报动压力的分布,为磨削加工提供参考。      

Improving grinding performance by controlling air flow around a grinding wheel

In grinding, high specific heat is generated, and hence, appropriate control of temperature through effective flow of grinding fluid is necessary to obtain a quality ground surface. It is known that in conventional fluid delivery method, most of fluid is wasted due to presence of a stiff air layer around the grinding wheel. This air layer is generated around the wheel due to the rotation of the porous grinding wheel at a high speed. To improve grinding performance, hence, penetration into this air layer is required.In this work, a pneumatic barrier set-up has been developed for controlling the stiff air layer around the grinding wheel. The formation of stiff air layer has been studied experimentally by measuring the variation of air pressure around grinding wheel periphery at different parametric conditions of pneumatic barrier. This pneumatic barrier tends to break the stiff air layer before the fluid flow area or grinding zone. A remarkable amount of reduction in pressure of the air layer is observed at the fluid flow zone. To observe beneficial effects of suppressing the air layer, grinding experiments are performed under dry, flood cooling and flood cooling with pneumatic barrier setup. Reduction of grinding forces and surface roughness are clearly observed with the use of pneumatic barrier setup, and hence, its applicability.     

磨削区内气流场速度和压力分布规律的研究进展

在高速旋转的砂轮表面形成一层空气附面层，即气流场。气流场的存在，不仅影响工件的加工精度和加速砂轮的磨损，而且还阻止磨削液有效地注入磨削区，使加工条件恶化，磨削力上升，磨削温度升高，严重影响了工件的加工质量和表面完整性。本文综合分析了在磨削区速度和压力的分布规律及影响因素，为今后工业生产中进一步控制、利用气流场进行磨料流光整加工奠定基础。     

Experimental simulation of the efficiency of high speed grinding wheel cleaning

The grinding of certain materials such as ductile material which are hard to grind implies particular conditions of work. Maintaining the cutting ability of the wheel is necessary and wheel cleaning is one of these conditions. In this paper, the parameters which are influential in maintaining a clean wheel are identified. A cleaning criterion is proposed to estimate the efficiency of the cleaning process. Using an experimental setup, the significant of the influence of the nozzle position, the flow rate and pressure, the boundary layer of air around the rotating wheel and the particle rate contained in the fluid are assessed. It is observed too that the fluid temperature has no significant effect. Lastly, the best method to clean a wheel when high speed grinding is discussed.     

Useful coolant flowrate in grinding

A model has been developed for flowrate between a rotating grinding wheel and a workpiece. It was found that the useful flow that passes through the contact zone is a function of the spindle power for fluid acceleration, wheel speed and delivery-nozzle jet velocity. Two loss coefficients having values less than 1 are required to be calibrated for the particular grinding wheel and fluid delivery type. The model is then valid for a range of nozzle flowrates for the particular wheel and nozzle conditions. The flowrate delivered is related to unit width of the delivery nozzle assumed to be unit width of grinding contact. The model makes it possible to determine a suitable value of nozzle outlet gap to achieve a required fluid film thickness in the grinding zone. A guide is given to optimisation of the jet velocity in relation to the power required to accelerate the fluid and the particular velocity of the wheel. The model has been validated experimentally. Its simplicity and accuracy allow application to a wide range of grinding situations.     

Improving grinding fluid delivery using pneumatic barrier and compound nozzle

Grinding fluid is commonly applied to control grinding defects caused by high grinding zone temperature. Delivery of fluid to the grinding zone is obstructed by the formation of a stiff air layer around the grinding wheel. This results in huge wastage of grinding fluid. In the present paper, results of using a pneumatic barrier and a compound nozzle are discussed with respect to delivering fluid deep into the grinding zone. Grinding fluid passing through the grinding wheel contact zone is measured under different modes of fluid delivery using a flood cooling, or a compound, nozzle, with or without the application of a pneumatic barrier. It is found that the system using a pneumatic barrier with flood cooling nozzle, and that employing a compound nozzle perform better than the flood cooling nozzle. A compound nozzle along with a pneumatic barrier renders substantially less wastage of grinding fluid even at a low flow rate of grinding fluid. Above a fluid discharge of 475 ml/min, the compound nozzle alone shows effective penetration of grinding fluid through the grinding zone. Reduction of grinding force, specific energy and roughness of ground surface are obtained after using compound nozzle fluid delivery system. Compound nozzle may be used instead of flood cooling nozzle as it improves grinding performance even using 52.5 % less discharge of grinding fluid.     

凸轮轴摆动磨削几何学建模及分析北大核心

为研究摆动磨削工艺对表面质量的影响机制,基于恒线速度磨削工艺,分析凸轮旋转一周时凸轮轴角速度和角加速度、砂轮进给速度和加速度的变化规律;对比分析摆动磨削与常规磨削时的接触长度和最大未变形磨屑厚度。结果表明:在不同的凸轮基圆速度下,凸轮轴转动的角速度和角加速度、砂轮进给速度和加速度呈线性增长趋势;摆动磨削可改善磨削表面的质量,且改善效果受磨削参数的影响;磨削深度对磨削表面质量有弱化作用;适当提高砂轮直径、砂轮转速、凸轮速度、摆动幅度、摆动频率可提高磨削表面质量。     

Cooling action of grinding fluid in shallow grinding

A new method is proposed for measuring the heat transfer coefficient in the vicinity of the wheel-workpiece contact zone. The accuracy of measurement is estimated by using a finite element method and the factor for correcting the measured results is derived. The experiments are performed in a number of conditions where grinding fluid is supplied and the following measures are consequently recommended for increasing the cooling efficiency: (1) set the velocity of coolant to more than the critical value to penetrate the air flow layer formed around the wheel periphery; (2) use a nozzle with a thin throat, about 1 mm in height, and attach a scraper plate above the nozzle outlet; (3) choose a wheel of large grain size and dress roughly, or form shallow grooves on the wheel periphery; and (4) set a higher wheel speed.     

聚晶金刚石刀具研磨质量及去除机理研究

针对聚晶金刚石（PCD）刀具的研磨质量问题,选择刃口钝圆半径、刃口缺陷度、后刀面粗糙度作为评价指标进行工艺参数的优化试验,并分析PCD的研磨去除机理。结果表明:工作台调定压力对刃口钝圆半径影响最显著;金刚石砂轮对刃口缺陷度影响最显著;砂轮转速对后刀面粗糙度影响最显著。选择4/5陶瓷基金刚石砂轮、1 000 r/min砂轮转速、170 N工作台调定压力可以获得研磨质量较高的PCD刀具。试验条件下,PCD的主要去除方式为划擦作用与微细破碎。1 000 r/min砂轮转速、170 N工作台调定压力下的微细破碎在保证较小刃口钝圆半径与刃口缺陷度的同时,可以获得相对平整的PCD表面。