无心磨削动态成圆模型与数值仿真

为了对无心磨削系统的工件动态成圆过程进行真实有效的数值仿真以及对工件的最终圆度进行科学合理的预测,建立了一种考虑工件中心瞬时位置变化的无心磨削动态成圆模型并对其进行了数值仿真。首先分析了磨削过程中由于工件表面形貌改变导致的工件定位中心位移以及磨削系统的振动引起的工件中心位移对工件中心瞬时位置变化的影响,然后综合考虑无心磨削过程中砂轮和工件之间的相互耦合作用、材料去除关系建立了工件磨削动态成圆模型,最后利用所建立的动态成圆模型和模拟工件材料去除及圆度变化的迭代算法,对工件外圆动态成圆的过程进行了数值仿真,再现了工件材料去除和轮廓形成的整个过程。通过对仿真算例结果的分析,证实了所提出的无心磨削动态成圆模型和迭代算法的真实性和合理性,对无心磨削成圆过程研究具有一定指导意义。     

无心磨削成圆过程仿真系统的研究与开发

首先介绍了工件成圆误差的定义及计算方法,然后在分析无心磨削加工的工件成圆过程的基础上,以VC、OpenGL为开发工具,采用VC与MATLAB联合编程的方法,设计开发了无心磨削成圆过程仿真系统.仿真结果与实验数据一致,具有良好的实用价值.     

无心磨削成圆过程仿真系统的研究与开发

首先介绍了工件成圆误差的定义及计算方法,然后在分析无心磨削加工的工件成圆过程的基础上,以VC、OpenGL为开发工具,采用VC与MATLAB联合编程的方法,设计开发了无心磨削成圆过程仿真系统。仿真结果与实验数据一致,具有良好的实用价值。     

干式气缸套外圆无心磨削加工浅析

外圆无心磨削是工件不定心的磨削,是一种适应大批量生产的高效率磨削方法。在干式气缸套生产线上,采用外圆无心磨削来加工气缸套的外圆直径也是一种比较先进的工艺措施。本文根据多年的生产经验和实际情况,对干式气缸套外圆无心磨削的加工原理,外圆直径的成圆过程,导轮曲面及修整和无心磨削加工的产品质量与控制等方面透行分析探讨。     

最佳无心磨削条件的设定

一、前言无心磨削因其工件支承刚性较高，是一种兼备高效、精密双重优点的加工方法。但是，磨削工件的圆度误差又不可避免地受到中心高角r，托板项角中，工件转速n。及单位磨除率Z’等诸多因素的制约。为将无心磨削的圆度误差控制在最小值，本研究通过计算机模拟分析，探讨了最佳无心磨削条件（几何关系和工艺参数）的设定，并通过磨削试验对其进行验证。实践结果表明：1．通过计算机模拟来设定最佳无心磨削条件是一种行之有效的方法；2．调整工件转速n。可减小磨削工件的圆度误差；3．无心磨削条件中的关键参数是中心高角r和加工弹性参数K…     

轴颈外圆磨削成圆过程的双转子耦合模型及仿真算法

主轴轴颈外圆的圆度对机床主轴部件的回转精度具有直接而重要的影响。磨削加工是实现轴颈外圆高精度加工的最重要的手段。虽然磨削技术在主轴外圆加工上已长期应用,但是利用现有的研究成果,还难以对一个既定的磨削系统的磨削成圆过渡过程进行完整有效的定量仿真,也难以对磨削工件的最终圆度进行科学合理的预测。在吸收国内外磨削转子系统模型成果的基础上,进一步考虑外圆磨削过程中砂轮和工件之间的相互耦合作用、材料去除、转子振动及变形协调规律,建立了外圆磨削系统的双转子耦合振动模型,提出了模拟轴颈材料去除和圆度变化的"磨削力-瞬时磨削深度"迭代算法。利用所建立的双转子模型和迭代算法,对不同磨削策略下轴颈外圆成圆的过渡过程进行了定量仿真,再现了轴颈材料去除和外圆轮廓变化的全过程;比较研究了不同磨削策略对磨削效率和最终加工圆度的影响规律。进行了相应的磨削试验和对比验证,试验结果证实了所提出的轴颈外圆磨削的双转子模型和迭代算法的有效性和合理性。     

存在不平衡量工件的无心磨削

一、前言无心磨削具有较高的工件支承刚性，除可用于批量加工单纯圆柱形工件外，还能磨削阶梯轴、外国有局部缺口或存在不平衡量等形状复杂的工件。但在磨创这几类工件晚因受工件形状、重量以及不平衡量的影响，其加工精度帼度质疑要低于磨削单纯圆柱形的工件。关于外国有局部缺口工件的无心磨削、轻型工件的无心贯穿磨创、阶梯轴的重负荷无心磨削、以及对工件外圆和凸缘同时进行无心磨削的研究，都已有专题论文介绍，但有关无心磨动存在不平衡工件的论述多为一般性的，至于专题研究不平衡量对无心磨削精度的影响则更为罕见。所谓存在不平衡…     

CBN砂轮在无心磨床上的高精度磨削

无心磨削,是高精度、高效率批量加工零件不可缺少的磨削方式。使用陶瓷结合剂CBN砂轮将会进一步提高无心磨削的加工效率。由于CBN砂轮的克努普硬度高达4700HK,所以对砂轮整个工作面的高精度修整技术很值得研究。外圆磨削中的逆磨切入角一般是5′～10′,无心磨削中顺磨切入角一般为1°～3°(如图1所示)。硬度高的CBN磨粒,可用大切入角磨削工件,而与外圆     

同时加工内外圆表面的无心磨床

近几年来，世界各国磨床制造厂为了在保证加工精度的同时，力求提高其生产效率，降低制造成本，都纷纷投入大量人力物力开发研制多功能复合化磨床。以高效率著称的无心磨床要实现多功能复合化是十分困难的。日本米克隆精密株式会社对无心磨削的工件进行了分析研究，发现无心磨削的工件中，有约20～25％的工件经外圆磨削之后，要以外圆为基准磨削内圆表面，因而提高其加工精度、生产效率，降低生产成本受到了一定的限制。历来历来磨削滚动轴承内、外套圈之类的环形零件，为了确保端面与内外圆表面的垂直度，都是以端面为基准的。如果以端面为…     

外圆磨削砂轮形貌仿真与工件表面粗糙度预测

对磨削砂轮形貌、外圆磨削过程及工件表面形貌进行了仿真,实现了对工件表面粗糙度的预测,并对仿真模型进行了验证。采用Johnson变换和Gabor小波变换,实现了高斯域和非高斯域的转化,在随机域内对磨削砂轮形貌进行了仿真。根据外圆磨削运动过程,通过对砂轮和工件相互作用过程的分析,建立了磨粒运动轨迹方程和工件形貌方程,在考虑磨粒切削、耕犁与摩擦作用的条件下,对外圆磨削过程进行了仿真。建立了外圆磨削模型,实现了对加工工件形貌的仿真和粗糙度预测。     

基于工件定位误差修正算法的无心磨削过程仿真研究

为合理地描述无心磨削过程,提出了一个关于工件表面误差引起的定位误差的修正算法,建立了基于该算法的无心磨削静态成圆仿真模型.通过VB6.0编程及MATLAB6.5仿真分析.在嵌入与生产实际相符的数据后,可得到磨削过程中的工件圆度误差变化曲线.通过对比,表明所提算法是合理的.     

Modeling of the centerless through-feed grinding process

A computer simulation method for investigating the form generation mechanism in the centerless through-feed grinding process is described. The length of the contact line and the magnitude of the grinding force between the grinding wheel and workpieces, vary with the change in the axial location of the current workpiece during grinding. Thus, a new coordinate system and a grinding force curve of previous and/or following workpieces are introduced to treat the axial motion. Experiments and computer simulations were carried out using four types of cylindrical workpiece shapes. To validate this model, simulation results are compared with the experimental results.     

Modeling of the axial movement of parts during centerless through-feed grinding

There are two major differences between the centerless infeed grinding process and the centerless through-feed grinding process. One is an axial movement of workpieces, and the other is that several workpieces are ground simultaneously and continuously by through-feeding. Because of these dilfferences, through-feed ground parts inherently possess not only the roundness error but also the tapering error. The aims of the research reported in this paper are to examine this inherent tapering characteristic and to find the effects of grinding variables (center height angle, regulating wheel tilt angle, and shape of grinding wheel surface). To accomplish the objectives, experiments were carried out using two types of cylindrical workpiece shapes. Also, computer simulations were performed using the 3-D through-feed grinding model.     

COMPUTER SIMULATION OF BELOW-CENTER AND ABOVE-CENTER CENTERLESS GRINDING

Centerless grinding of ceramic components in the conventional above-center mode under aggressive conditions often results in workpiece spinning. One way to avoid workpiece spinning is to use below-center grinding, but this can lead to problems with part rounding and lobing. The present investigation was undertaken to develop a practical simulation to assist in the selection of acceptable set-up conditions for centerless grinding. From the initial workpiece profile and set-up conditions as input, the simulation predicts workpiece spinning and the progressive change in the workpiece profile for both above-center and below-center grinding. Simulation results for workpiece lobing were found to be consistent with experimental results obtained for below-center grinding of zirconia specimens.     

圆柱滚子外圆精密加工技术综述

圆柱滚子外圆精密加工技术作为圆柱滚子制造流程的终加工手段,对保证圆柱滚子的形状精度、尺寸精度、表面质量及其一致性起到关键作用。目前,依据加工原理不同,圆柱滚子加工方法主要分为无心磨削和无心超精研的工业主流传统加工方法,以及定心往复超精研、电化学机械光整、磁流体研磨、双平面方式超精研抛等非传统加工方法。介绍了上述不同加工方法的基本加工原理和研究现状,在加工精度、表面质量、生产效率等方面讨论了各加工方法的优缺点;展望了圆柱滚子外圆精密加工技术未来的发展方向,包括超精密工件和设备、高效自动化生产、高柔性生产、微小型零件、复合工艺、智能装备等。     

A feasibility study of microscale fabrication by ultrasonic-shoe centerless grinding

The present authors proposed a new centerless grinding technique, namely ultrasonic-shoe centerless grinding, which they validated experimentally in a previous study [Wu Y, Fan Y, Kato M, Wang J, Syoji K, Kuriyagawa T. A new centerless grinding technique without employing a regulating wheel. Key Eng Mater 2003;238–239:355–60]. Rather than a regulating wheel as in conventional centerless grinding, the new method uses a plate-shaped ultrasonic shoe, on the end face of which micro elliptic motion is generated, to support the workpiece and control its rotational motion. This enables the fabrication of a microscale cylindrical component less than 100 μm in diameter with an extremely large aspect ratio, which is extremely difficult to produce by conventional machining techniques. In the present study, in order to develop a novel technique for the fabrication of microscale cylindrical components, first an apparatus capable of microscale fabrication was designed and constructed based on the ultrasonic-shoe centerless grinding method. Following initial performance tests, the apparatus was tested by conducting a grinding run on a tungsten carbide test-piece, 0.6 mm in diameter and 15 mm in length. The result was a microscale cylindrical component, around 60 μm in diameter and 15 mm in length, with an aspect ratio of over 250, which validated the new technique proposed for microscale fabrication.     

Modeling and simulation of grinding surface topography considering wheel vibration

Grinding is an important means of realizing precision and ultra-precision machining. Vibration caused by an unbalanced grinding wheel in grinding process has a significant impact on the quality of workpiece surface. However, the effect of wheel surface topography and/or the relative vibration between grinding wheel and workpiece are not considered in most researches. Taking the relative vibration between grinding wheel and workpiece into account, alongside the abrasive grain trajectory equation, a new analysis and simulation model for surface topography of the grinding process is established. The model for the topography of the grinding wheel surface is first studied, and subsequently, a new simulation model for surface topography of the grinding process is proposed. Case studies are performed at the end, and the influence of grinding wheel vibration amplitude, wheel grit number, as well as grinding parameters on the surface waviness and roughness is discussed. The simulation results could be used to optimize the actual grinding process to improve the ground surface quality or predict the surface topography by given grinding parameters.     

Modeling of the centerless infeed (plunge) grinding process

A computer simulation method for investigating the form generation mechanism in the centerless infeed (plunge) grinding process is described. For a 3-D simulation model of form generation, contact points are assumed to be on least squares contact lines at the grinding wheel, regulating wheel, and work-rest blade. Using force and deflection analyses, the validity of this assumption is shown. Based on the 2-D simulation model developed in the previous work and the least squares contact line assumption, a 3-D model is presented. To validate this model, simulation results were compared with the experimental works. The experiments and computer simulations were carried out using three types of cylindrical workpiece shapes with varying flat length. The experimental results agree well with the simulation. It can be seen that the effect of flat end propagated to the opposite end through workpiece reorientation.     

超声振动辅助磨削加工智能控制技术研究

根据超声振动辅助磨削加工的特点,结合检测难易程度和实际需要,选择磨削力比作为输入。利用磨削力检测系统获得磨削力比实时数据,对采样结果进行分析处理。采用分级控制,分别控制超声功率和工件进给速度。将磨削力比的变化和变化率作为模糊控制器的输入,工件进给速度作为控制器的输出。根据模糊控制规则,利用Matlab提供的Simulink仿真模块,对超声振动辅助磨削加工模糊控制系统进行了动态仿真,仿真结果符合模糊策略,进给速度能够随着磨削力比的变化实现调整,从而避免产生磨削烧伤和颤振。     

异形滚柱的在线电解修型成型磨削工艺试验研究

介绍了一种用于汽车和摩托车上先进超越离合器异形滚柱的在线电解成型(ELID)磨削加工工艺试验及相关设备与装置,主要包括成型磨削的工艺实施方案,在平面磨床上实现成型磨削的工装设计及在线电解砂轮修型的装置设计与布局等问题。理论上分析了ELID成型磨削在加工中能按照理想的成型曲线自动修正砂轮母线的形状,从而达到很高的形状精度和较低的表面粗糙度。总结了影响加工质量和效率的因素和规律;同原来的成型拉削相比,采用成型磨削具有效率、质量与稳定性、工具成本和管理等方面的诸多优势。