激光在磨削加工中的应用现状分析及试验研究

本文阐述了激光技术在磨削加工不同方面的应用情况。首先介绍了利用激光对工件表面进行改性处理以改善工件磨削加工性能以及激光辅助磨削硬脆材料的原理和方法。然后通过试验研究,着重阐述了激光在砂轮修锐以及检测砂轮表面形貌两方面的应用。试验结果表明,利用激光扫描方法可快速精确地测量砂轮表面的原始三维形貌,对砂轮工件性能作出客观评定,利用该方法可望实现砂轮形貌的在线检测;利用激光修锐砂轮,不仅可大大降低砂轮损耗,并且能精确控制修税效果,因而是一种很有前途的砂轮修锐方法。     

氮化硅陶瓷球面磨削表面破碎损伤研究

用金刚石砂轮磨削氮化硅陶瓷材料时,后者容易产生表面破碎损伤.为检测和控制这种损伤,进行了不同工艺参数条件下的氮化硅陶瓷材料球面磨削实验,利用光学显微镜对磨削后的表面进行观察和分析,并获得磨削表面图片.采用表面破碎率衡量球面磨削表面的损伤程度,通过MATLAB软件对磨削后的表面形貌图进行分析及计算,并得出结论:表面破碎率随砂轮粒度的增大而减小,随磨削深度的增大而增大,随砂轮线速度和砂轮进给速率的增大而保持稳定.     

基于二维位移传感器的砂轮表面形貌测量

砂轮表面的三维形貌对保证其磨削质量有重要意义。采用高精度二维位移传感器在线测量砂轮的表面形貌,再通过建立的砂轮三维形貌基准平面和数字滤波方法,用测量数据计算得到砂轮表面的三维形貌评价参数。结果表明:该评价参数与Zeta自动三维测量系统的测量结果基本相同,验证了该评价方法的有效性和实用性,可为砂轮修整及其磨削加工提供参考指标。      

刚玉砂轮缓进深切磨削K444镍基高温合金研究

为评价K444高温合金的磨削加工性能,采用棕刚玉砂轮和白刚玉砂轮进行磨削试验,对比分析其磨削力、磨削比能、磨削工件的表面形貌和表面粗糙度以及砂轮磨损.结果表明:相比于白刚玉砂轮,棕刚玉砂轮的磨削力更小,磨削后工件表面粗糙度低,其表面粗糙度Ra在0.206～0.455μm,更易获得光滑的磨削表面.对表面粗糙度的敏感度分析...     

结构化砂轮拓扑磨削鱼鳞表面原理及仿真分析

为了磨削出鱼鳞表面的几何形貌,基于对鱼鳞表面形貌的特征分析,建立了鱼鳞表面数学模型。依据建立的鱼鳞表面数学模型,结合磨削运动原理以及点集拓扑学理论的分析,设计出了一种用于磨削鱼鳞表面的结构化拓扑砂轮。依据磨粒平面运动轨迹方程,讨论实现鱼鳞表面磨削的条件,并通过MATLAB对设计的砂轮进行磨削运动学仿真,获得了鱼鳞表面结构。仿真结果表明:使用设计的结构化砂轮磨削工件表面可以获得鱼鳞表面,当保持砂轮转速不变时,改变砂轮进给速度、磨削深度对鱼鳞表面磨削结果均能产生不同的影响。     

SG砂轮磨削镍基合金GH4169砂轮磨损机理与磨削性能的实验评价

目的 减少磨削镍基合金GH4169过程中砂轮磨损和堵塞现象,提高工件表面质量.方法 采用WA和SG砂轮磨削镍基合金GH4169,通过观察磨削前后砂轮表面微观形貌,研究两种砂轮表面材料粘附、堵塞以及磨粒破碎等主要磨损机制.从磨削力、工件表面形貌、磨削比能3个方面评价两种砂轮的磨削性能,并探究磨削参数对砂轮磨削力、工件表面形貌、磨削比能的影响规律.结果 在去除相同体积材料时,SG砂轮的磨削力较小,所消耗的能量较WA砂轮低21.5％,SG砂轮所加工工件表面的粗糙度明显低于WA砂轮所加工工件表面的粗糙度,两者表面粗糙度差值均在1μm以上.SG砂轮表面材料粘附现象较轻,WA砂轮表面出现了大面积的材料粘附,造成了砂轮堵塞.结论 SG磨粒因内部致密的微小晶粒所决定的微破碎机制,使SG砂轮在磨削镍基合金GH4169过程中保持了锋利的磨削刃,减少了砂轮表面的材料粘附,同时也获得了良好的工件表面质量.另外,SG磨粒较WA磨粒具有更佳的力学性能,使其在去除相同体积材料时所消耗的能量更少.     

激光功率谱检测砂轮形貌的试验研究

本文应用激光功率谱在线检测砂轮磨损装置,研究磨削条件对砂轮磨损的影响,以及对磨削过程进行在线监测。试验结果表明,本检测装置可获得砂轮工作面一周形貌的特征参数及曲线,由此可定量地评价砂轮的磨削性能,科学地标定砂轮耐用度。     

激光功率谱检测砂轮开貌的试验研究

本文应用激光功率谱在线检测砂轮磨损装置，研究磨削条件对砂轮磨损的影响，以及对磨削过程进行在线监测。试验结果表明，本检测装置可获得砂轮工作面一周形貌的特征参数及典线，由此可定量地评价砂轮的磨削性能，科学地标定砂轮耐用度。     

石墨自润滑钎焊CBN砂轮磨削镍基高温合金温度的试验研究

利用石墨自润滑钎焊CBN砂轮和陶瓷CBN砂轮进行了高温合金GH4169磨削对比试验,采用夹丝半人工热电偶方法测量工件表面磨削温度,并运用扫描电镜、能谱仪对砂轮表面磨粒的微观形貌及元素分布情况进行分析。结果表明:在相同磨削条件下,多层自润滑钎焊CBN砂轮磨削GH4169高温合金的磨削温度比陶瓷结合剂CBN砂轮低100℃左右;砂轮表层的磨粒表面形成一层石墨薄膜,有助于减小摩擦,从而降低磨削温度。     

超声振动螺线磨削砂轮表面的功率谱密度分析

超声振动螺线磨削过程中,砂轮表面微观形貌的变化复杂.为准确表征其特征,采用功率谱密度分析方法,将砂轮表面的微观结构分解为不同频率、振幅和相位的谐波,对比分析不同磨削行程时普通磨削和超声振动螺线磨削砂轮表面的磨损行为.结果表明:砂轮表面功率谱密度曲线的斜率k随着磨削行程的增大而逐渐减小,即k越小砂轮表面磨损越严重.其中,...     

Influence of surface topography evolution of grinding wheel on the optimal material removal rate in grinding process of cemented carbide

Most of the reported studies on the optimization of grinding parameters do not consider the evolution of the surface topography of grinding wheels, and the established empirical models will no longer apply when the surface conditions of the grinding wheel changes. In this paper, an integrated model based on the surface topography of grinding wheel is established. The grinding process of cemented carbide is simulated using the established model, and the simulation results are analyzed to obtain the surface roughness model and the specific grinding energy model based on the undeformed chip thickness distribution. Subsequently, the grinding constraint models are defined according to the two grinding constraints—surface roughness and specific grinding energy. Through inversion analysis, the maximum material removal rate of the given grinding wheel surface conditions satisfying the defined grinding constraints are obtained, and the influence rules of the grinding wheel surface conditions on the maximum material removal rate are analyzed. Then the grinding wheel surface conditions are adjusted by changing the radial dressed height of the grinding wheel and the arrangement distance of the grains in wheel circumferential direction to improve the maximum material removal rate of the grinding wheel. Finally, the optimization results are verified through grinding tests of cemented carbide.     

砂轮表面形貌仿真方法研究

砂轮表面形貌对磨削加工过程和已加工表面质量有着极大影响,但由于砂轮表面磨粒分布的随机性,描述砂轮表面形貌非常困难。通过对砂轮表面进行采样和数据处理,运用统计学理论和Johnson变换方法获得了非正态分布砂轮表面形貌的数学描述方程,在此基础上对砂轮表面形貌进行仿真。选用伯明翰14参数集的部分参数作为评价标准,对测量的砂轮表面形貌和仿真形貌进行比较,结果显示:二者具有很好的一致性,6个参数的平均相对误差仅为2.97%。结果充分证明了该仿真方法的正确性。      

Analysis and simulation of the grinding process. Part I: Generation of the grinding wheel surface

This paper is in three parts describing the analysis and simulation of the grinding process. This first part is concerned with the generation of the wheel surface by single point diamond dressing. In grinding, the grinding wheel has to be dressed periodically to restore wheel form and cutting efficiency. Understanding the process of generating the grinding wheel surface is important for the control of the grinding process. Generation of the wheel surface is simulated as a single diamond dressing process on a computer generated wheel. The wheel is simulated by grains randomly spaced in the wheel volume. The topography of the wheel cutting surface is generated by simulating the action of an ideal dressing tool as it dresses the wheel. The simulation of the wheel topography takes account of the motion of the dressing tool, grain size, grain spacing, grain fracture and grain break-out. The simulated cutting surface is used for further simulations of grinding. The simulation of grinding using the simulated grinding wheel surface is described in Sections 2 and 3 where a comparison is made of results predicted from simulation with results obtained from experiments. By matching simulated and experimental results, it is possible to explain the relative importance of dressing and grinding parameters.     

Numerical modelling of ground surface topography: effect of traverse and helical superabrasive grinding with touch dressing

Grinding processes are often used for final finishing of components because of their ability to satisfy stringent requirements of surface roughness and dimensional tolerance. Surface topography generated during grinding depends upon many parameters like wheel parameters, wheel velocity, downfeed, grit density etc. and it also depends upon the type of grinding procedures (viz. plunge grinding, traverse grinding, helical grinding, touch dressing etc.) employed. Therefore, a correct examination of the parameters and type of process employed to carry out grinding are necessary. This paper is an attempt to develop the relation between the different grinding parameters and the grinding procedures like plunge, traverse and helical superabrasive grinding with touch dressing and the average surface roughness. For this purpose, a numerical simulation technique has been implemented to generate the grinding wheel topography. The ground workpiece surface has also been generated by simulating removal of work material depending upon the trajectory of the abrasive grits on the grinding wheel without taking rubbing and ploughing into consideration.     

Simulation of precision grinding process, part 1: generation of the grinding wheel surface

This paper is in two parts describing the kinematic simulation of the grinding process. The first part is concerned with the generation of the grinding wheel surface. A numerical procedure for effectively generating the grinding wheel topography is suggested. The procedure is based on the transformation of a random field. The sufficient condition for the transformation is discussed, and two transformations satisfying the condition are introduced. Numerical examples are used to illustrate the viability of the approach. It will be shown that the generated and measured grinding wheel topography share the same probabilistic characteristics.     

In-process measurement of topography change of grinding wheel by using hydrodynamic pressure

This paper deals with an in-process measurement method for topography change of a grinding wheel, which can apply to wet grinding. A pressure sensor is set beside a grinding wheel with a small gap. When grinding fluid is dragged into the gap, hydrodynamic pressure, which corresponds to the gap length and the topography, can be measured. This method is applied to a cylindrical grinding machine. No electromagnetic properties of a workpiece and a grinding wheel affect measured results. The pressure is decreased with the increase of the gap length when the grinding fluid is supplied in the tangential direction of the grinding wheel. Spectra of the pressure are measured with an FFT analyzer. Higher frequency components are increased with the progress of grinding because of turbulent flow. Loading and dulling of a grinding wheel can be detected by the proposed method as well as its wear.     

单层钎焊CBN砂轮表面形貌重构与磨粒切厚分布特征研究

为了更加准确地研究磨削加工机理及预测磨削结果,测量并重构单层钎焊CBN砂轮的表面形貌,并以此为基础研究不同工艺参数下的单颗磨粒切厚分布特征。结果表明:试验砂轮表面磨粒高度的分布形态并不符合正态分布特征,需要采用Johnson变换重构整个砂轮表面的磨粒高度分布特征;单颗磨粒切厚分布特征受磨削参数和砂轮磨损的影响较大。      

Simulation of diamond-ground surfaces

State-of-the-art models available for predicting the characteristics of diamond-ground surfaces entail digitization of wheel topography which limits their practical utility. This paper presents a geometric simulation of surface generation in diamond grinding, that utilizes wheel topography data obtained from simulated three-dimensional structure of the diamond grinding wheel. Simulation results are validated by surface grinding experiments on a variety of materials that exhibit different material removal mechanisms, with the roughness parameters R_a and R_t, the autocorrelation function and the fractal dimension as the comparison indices. A parametric study on the effect of various grinding parameters on surface finish is also reported, with particular emphasis on identifying and minimizing process-inherent variability.