陶瓷结合剂CBN砂轮高速磨削凸轮轴的表面粗糙度研究

本文通过一系列的试验,分析了磨削工艺参数对工件表面粗糙度的影响,建立了磨削表面粗糙度的经验公式,研究了陶瓷结合剂CBN砂轮磨削表面粗糙度的变化规律及其特点,这些规律为凸轮轴的CBN高速磨削提供了一系列实用的工艺参数.     

基于灰色系统理论的外圆磨削工艺参数优化研究

针对难加工材料的高精密外圆磨削加工工艺参数优化问题,以磨削工件表面粗糙度和工件圆度均方根值作为试验评价指标,使用正交试验方法对各工艺参数进行试验设计,基于灰色度分析方法对实验各工艺参数进行分析计算优化。实验结果证明了该方法在分析优化磨削工艺参数的有效性和实用性。     

K9玻璃磨削亚表面损伤深度预测模型及实验研究

基于压痕实验原理,建立了K9玻璃亚表面损伤深度预测模型。为获得预测模型中的未知参量,开展了K9玻璃磨削实验。利用激光扫描共聚焦显微镜检测工件磨削后的表面粗糙度值,利用扫描电镜检测磨削后的工件表面微观形貌和亚表面损伤层形貌,分析了工艺参数对表面粗糙度值和亚表面损伤深度的影响规律。考查了工艺参数对法向磨削力的影响规律,并根据实验数据,采用多元线性回归拟合法得到法向磨削力的经验公式,进而确定了亚表面损伤深度预测模型的参数。模型预测值与实验值具有较好的一致性,表明预测模型具有一定的可靠性。     

基于正交试验-遗传神经网络的陶瓷球面精密磨削参数优化

针对陶瓷等难加工材料的精密加工要求与特点以及球面磨削传统加工模式,分析了氮化硅陶瓷材料球面廓形工件砂轮法向跟踪精密磨削的方法。采用正交试验法设计试验,运用极差法和方差法综合分析相关磨削工艺参数对工件加工质量与效率的影响规律。考虑到当前磨削加工工艺方案选择与优选的难点,利用遗传神经网络算法建立了工件加工质量与效率和相关磨削工艺参数之间的非线性映射关系,并基于正交试验法的分析结果对遗传神经网络算法进行了改进,实现了相关磨削工艺参数的优化,缩短了氮化硅陶瓷材料球面廓形工件数控磨削工艺制定与操作的时间,提高了磨削加工质量和效率。     

砂带磨削加工表面粗糙度预测与验证

为了研究砂带磨削过程中主要工艺参数对磨削表面粗糙度的影响规律,建立了砂带磨削工件的表面轮廓模型,通过对砂带磨粒运动轨迹的研究分析,由单个磨粒的运动方程建立多个磨粒的运动方程。采用单因素试验法,由仿真软件合成磨削加工表面的三维形貌与粗糙度值的变化趋势,通过建立表面粗糙度回归数学模型与叶片磨削试验进行理论分析验证。结果表明,不同工艺参数磨削后工件表面粗糙度的仿真值与试验结果吻合度较好,为实际砂带磨削工艺参数的选择和优化提供理论依据与参考。     

高速精密磨削9CrWMn冷作模具钢的磨削力和比磨削能

分析了高速精密磨削9CrWMn冷作模具钢的机理,采用DEFORM软件对高速磨削模具钢9CrWMn过程进行了磨削力仿真。使用高精密高速平面磨床对模具钢9CrWMn进行了高速精密磨削试验,并在线测量了多种工况下的磨削力。结果表明:在其他两组工艺参数不变时,随着工件进给速度增加,磨削力特别是法向磨削力会增大近45%;法向磨削力和切向磨削力随着砂轮的线速度上升而下降,法向磨削力下降近33%;磨削深度对磨削力影响较大,大的磨削深度对法向磨削力的影响尤其显著,可使法向磨削力增大近100%。分析了磨削工艺参数对比磨削能的影响规律,结果显示:随着磨削深度和工件进给速度的增大,比磨削能呈比较明显的下降趋势,符合磨削加工中的尺寸效应;随着砂轮线速度的增大,比磨削能呈上升趋势。最后,对高速磨削前后工件表面的微观形貌进行了对比分析,磨削力试验结果和仿真理论分析相一致。     

超高速磨削工艺对45#钢表面磨削温度影响实验研究

在45#钢超高速磨削工艺实验的基础上,分析了砂轮线速度、磨削深度、工作台速度对工件表面磨削温度的影响,揭示了表面磨削温度随着砂轮线速度的提高而呈现先升高后下降的趋势,以及随磨削深度的增加而升高,随工作台速度的提高而下降的规律和机理,从而指导磨削参数的优化设计。     

轴承套圈ELID磨削参数研究

采用在线电解(ELID)磨削技术对轴承套圈进行精密磨削实验,研究了在相同的磨削时间内不同导电率的磨削液对工件表面粗糙度的影响规律,以及同一导电率的磨削液随着磨削时间变化对工件表面粗糙度的影响规律,利用正交试验法对轴承套圈的工艺参数进行优化设计,试验结果表明,当磨削液导电率在合理的范围内时,磨削液的导电率越大,工件的表面粗糙度就越小,对于同一导电率的磨削液,随着磨削时间的增加,工件表面粗糙度呈现小幅度的增大,利用正交试验优化得出的方案提高了轴承套圈的加工精度。     

CBN砂轮120m/s高速磨削表面粗糙度实验研究

本文针对不同的磨削参数对45钢、2Cr13、T10三种材料的影响程度进行研究，通过实验分析了CBN砂轮高速磨削三种材料时工件表面粗糙度的变化情况，提出了降低不同材料工件的表面粗糙度的高速磨削工艺参数的优化控制原则。     

PM泵凸轮轴磨削裂纹控制方法的探讨

通过对PM泵凸轮轴磨削过程中产生裂纹的原因进行分析,指出磨削温度、磨削应力及冷却效果是产生磨削裂纹的主要因素.实验表明,通过控制渗碳层厚度及正火、淬火和回火工艺参数,选用高速磨削,保持良好的砂轮和冷却液状态,能够减少凸轮轴磨削裂纹.     

凸轮轴数控磨削工件主轴转速优化建模与实验研究

根据凸轮轴X-C轴联动恒线速度磨削加工数学模型,建立了砂轮架进给位移与速度、凸轮工件主轴转速的理论方程。根据数控凸轮轴磨床加工能力的约束条件,对砂轮架进给中速度、加速度或加加速度值超出限定值的凸轮转角区间,通过积分反求方法求解出相应转角区间工件主轴所允许的转速值,并以该段转速值替换对应的转角区间上凸轮轴恒线速度磨削时理论转速值。对优化计算前后的工件主轴转速曲线进行了凸轮轴磨削加工实验。实验结果表明：采用优化后的凸轮工件主轴转速进行加工,相比于恒线速度理论转速加工,其升程最大误差与最大相邻误差减小,工件表面粗糙度降低,提高了凸轮轴高效精密磨削加工质量。     

MODELING AND SIMULATION OF WORKPIECE TEMPERATURE IN GRINDING BY FINITE ELEMENT ANALYSIS

The quality of ground workpieces is largely determined by the accuracy of dimensions and geometry, and by the surface finish. The thermal stress to which workpieces are subjected during the grinding process, characterized by the temperatures that develop, plays a major role as far as the economical fulfillment of high-quality requirements is concerned. Too high thermal stresses have a deleterious effect on the workpiece, leading to changes in specific service characteristics. This paper predominantly concerns experiments to determine the temperature when grinding cemented carbides. In this context, the temperature fields developing in the workpiece were examined for different grinding conditions, both on the basis of experiments and calculations by means of finite element analysis (FEA). The simulations show a rise in surface temperatures in the workpiece from the run-in to the run-out phase of the grinding process. The analysis indicates that the-grinding process gives rise to an inho-mogeneous distribution of the material properties of the workpiece, along the grinding direction.     

基于ANSYS的平面磨削温度场的有限元仿真

通过确定移动热源的加载方式,运用ANSYS软件的热分析模块对磨削温度场进行仿真分析,得到了不同载荷步的温度场分布以及不同深度的节点的温度变化曲线,验证了越靠近热源磨削温度越高以及工件下层材料温升显著低于工件表面。通过改变砂轮线速度、工件进给速度和磨削深度,得到了主要的磨削参数对磨削区温度场的影响状况,证明了钛合金磨削存在临界磨削速度。在临界磨削速度附近某一区间磨削温度出现回落,因此适当的磨削速度、高的工件进给速度和小的磨削深度可以有效的减小磨削温度。     

Residual stresses due to a moving heat source

An analytical model based on finite element method is presented for determination of the residual stresses of thermal and mechanical origin due to surface grinding process. The temperature field within the workpiece is determined as the quasi-steady state temperature distribution due to the moving heat source. An iterative procedure is employed for evaluation of the step-by-step movement of the temperature field and the force, in order to simulate the movement of the grinding wheel over the workpiece. Computation of the elastic-plastic stress history culminates in the residual stress state of the workpiece. Influence of the magnitude of mechanical force, the rate of heat input and the speed of movement of workpiece on the residual stress distribution, are discussed.     

凸轮轴磨削加工速度优化调节与自动数控编程研究

为进一步提高凸轮轴的加工精度、表面质量和加工效率,根据X-C轴联动磨床的运动原理,建立了凸轮轴恒线速加工理论数学模型,依据该数学模型采用三次样条拟合插值法,建立了凸轮转速优化调节的数值计算模型。结合具体凸轮轴零件及其磨削加工工艺方案的具体参数,计算出机床各运动轴加工过程的运动数据,在确保无工艺故障的前提下,最终把各轴的运动数据自动转换为对应数控控制系统的数控加工程序,从而实现了凸轮轴磨削的自动数控编程。最后在CNC8312A数控高速凸轮轴磨床上,对钱江32F型号凸轮轴的进气凸轮和排气凸轮分别进行磨削加工试验,得到了预期加工效果。试验验证表明,该加工速度优化调节及其自动数控编程方法在理论上和实践上都是可行的,完全满足实际生产的需要。     

Numerical and experimental studies on the temperature field in precision grinding of SiCp/Al composites

During precision machining of SiCp/Al composites, the temperature of the workpiece surface directly affects the machining quality. In this paper, a triangle heat source model was used to calculate the heat flow during grinding of SiCp/Al composites, then, a three-dimensional finite element method was employed to investigate the temperature distribution at different process parameters, i.e., grinding depth and feed speed of the worktable. In addition, the temperature measures using embedded thermocouple were applied to compare with predictions from the thermal model. The results indicate that the grinding temperature predicted by the finite element method agrees well with the experiment data, and the triangle heat source model was suitable for estimating the workpiece temperature of precision grinding.     

An in-situ infrared temperature-measurement method with back focusing on surface for creep-feed grinding

In creep-feed grinding research, it is vital to measure surface temperature of workpiece in order to optimize process parameters, prevent potential thermal damage, improve the surface integrity of workpiece and provide reference for modelling of grinding. Various measurement techniques for grinding temperature have been developed by using thermocouples and infrared radiation techniques. However, some inevitable problems still exist with slow response, strong noise interference and high sensibility to coolants. In order to obtain precise and reliable temperature of workpiece surface during grinding, an in-situ infrared technique is designed by focusing on the back surface of workpiece. With the help of a two-dimensional sliding table, the focus of infrared thermometer can be adjusted to the small hole in the workpiece to measure grinding temperature accurately. This method can avoid the high-frequency signal interruption of mechanical vibration and electrical noises, since the measurement is contactless and has signal shielding. The procedures to set up the measurement facility and measure grinding temperature are described in this paper. This paper also includes the analysis of measurement results of grinding temperature. Compared with other measurement techniques, this method is not affected by mechanical vibration and grinding fluids. By using infrared technology, this method can measure accurate grinding temperature with a fast response.     

氮化硅陶瓷镶块低粗糙度磨削的研究

提出氧化铝砂轮磨削陶瓷表面的加工过程是砂轮磨粒与工件表面凸峰的碰撞－碰撞与摩擦共同作用－摩擦抛光。对砂轮速度，工件转速、砂轮横向进给量、光磨次数，陶瓷材料硬度以及切削液等因素对表明粗糙度的影响进行了分析，表明氧化铝砂轮通过挤压和磨削抛光作用使陶瓷工件表面的粗糙度得到显著改善，实现了在普通磨床上对陶瓷材料的高质量加工。     

基于曲率圆的恒磨除率变速磨削模型分析

汽车凸轮轴加工的精度主要取决于它的轮廓曲线,要获得好的轮廓精度和表面品质,在磨削中采用恒定磨削线速度,使工件速度根据轮廓曲线的变化而变化,这样可以达到很好的轮廓品质,这个理论已经通过加工试验得到了很好的验证。但是随着技术的发展和凸轮轮廓数学建模的不断完善,现在又向着恒定磨除率的方向发展,理论研究表明可以获得更高的加工精度,利用凸轮的曲率圆方程,建立了恒磨除率模型,根据实际加工条件进行速度分析并利用MATLAB进行了仿真。