高液静压无心磨床磨削过程再生颤振的稳定性分析

为了避免高液静压无心磨床在磨削工件时发生颤振,从而提高工件的加工精度和磨削效率,提出了从再生型颤振机理出发,建立高液静压无心磨床磨削过程再生颤振动力学模型,制取无心磨削稳定性叶瓣图,选取适当加工工艺参数的方法。首先,应用再生颤振理论研究高液静压无心磨床磨削过程,进而建立了考虑工件和砂轮再生颤振的动力学模型,并在磨削力模型中利用时间延时来表示再生效应,通过对动力学模型进行求解,得到高液静压无心磨床磨削过程稳定性叶瓣图,并将稳定性叶瓣图划分为符合切入式无心磨削的4个区域,为工艺人员选取磨削工艺参数避免颤振提供了理论依据。     

有限随机进给法抑制磨削颤振的研究

通过变磨削用量法抑制颤振的机理分析，探讨了该方法抑制磨削颤振最佳效果的动态和静态条件，提出了满足此条件的磨削方法—有限随机进给法，初步实验结果表明，该方法具有抑制颤振的功能，有进一步研究和实用化的前景。     

轧辊磨削原理简析

通过对轧辊磨削的数学公式模型的定性分析,深入理解磨削理论,掌握磨削规律,从分析中得出优化轧辊磨削表面质量的思路和方法,介绍了优化铝箔轧辊磨削工艺参数的实例。     

CVC轧辊非对称磨损的磨削力均化方法

在板材轧制过程中,CVC轧辊会产生非对称磨损,严重影响板材加工的质量。针对CVC轧辊磨削过程中非对称磨损的大余量磨削阶段,提出一种磨削力均化的优化方法。根据CVC轧辊的工作特性,对其特有的非对称磨损辊形曲线进行分析;以减少大余量磨削过程中磨削力波动为目的,建立磨削力均化模型,并开发磨削力均化软件。结果表明：采用所提方法,磨削力的波动明显下降。     

CBN杯形砂轮端面磨削轧辊的磨削几何学分析

本文建立了CBN(立方氮化硼)杯形砂轮端面磨削轧辊的几何模型，从磨削几何学的角度研究了杯形砂轮端面磨削轧辊的磨削特性和输人参数对切人线长度和宽度的影响，分析了端面磨削外圆时的磨削接触弧的特点，结果表明，当切深较小时，砂轮与轧辊为点接触；已加工表面的粗糙度主要取决于砂轮外缘的磨粒密度；磨削效率的高低取决于砂轮内缘的磨粒密度；在磨削过程中，应根据其他参数的变化调节砂轮轴线与轧辊间的偏移量H；提高砂轮转速有利于磨削效率的改善。     

铝箔轧辊磨削和表面粗糙度

阐述了轧辊磨削参数和轧辊表面粗糙度的关系,为选定轧辊磨削参数提供了借鉴。     

轧辊磨床参数选择对轧辊磨削质量的影响

介绍了轧辊磨床参数的选择对于轧辊磨削质量的重要性,就砂轮、磨削冷却液和运动速度的匹配等工艺问题进行阐述,并介绍了实际工作经验。     

高速强力外圆磨削和外圆深切缓进给强力磨削时磨削力的研究

一、概述磨削力是直接说明磨削过程中砂轮磨削性能的重要参数,磨削力的大小直接反映了作用在砂轮磨粒切刃上的负荷的大小。所以,可以把磨削力的变化作为评价砂轮切削性能的指标;磨削力的法向分量将影响工艺系统的弹性变形,使工件产生残余留量、颤振等现象,对工件的尺寸精度和加工表面光洁度产生不利的影响;磨削力的切向分量的大小直接影响机床功率的选择,同时,磨削过程中消耗的能量大部分转变为热量,使磨削温度升高,从而影响工件尺寸精度及表面质量(烧伤等)。因此,磨削过程中力参数的研究一直受到重视。     

基于神经网络的轧辊磨削表面粗糙度智能预测

轧辊磨削精度和表面质量主要指磨削过程中的加工精度、表面粗糙度和物理机械性能,而表面粗糙度是其中最主要的一个因素。在轧辊磨削工艺中研究基于模糊神经网络的表面粗糙度预测,在加工过程中辨识表面粗糙度,保证了轧辊磨削质量的同时也提高轧辊磨削的生产率。     

高速磨床动态性能及变速磨削颤振的实验研究

为提高高速磨削表面质量,系统研究高速外圆磨床动力特性。通过设计动态性能试验,找到了样机的振动薄弱环节和主要振源,提出相应的改进措施。在改进后的高速外圆磨床上进行变速磨削颤振试验,结果证明变速磨削能在一定程度上抑制高速磨削颤振。     

轧机工作辊磨削振纹检测与控制

研究分析轧辊磨削振纹产生原因,通过对设备、砂轮、磨削工艺、操作等方面进行改进优化,研制了专用的辊颈振纹检测方法和分级控制规则,有效控制了磨削振纹的产生.     

Flank face texture design to suppress chatter vibration in cutting

Process damping is useful in improving chatter stability in a low cutting speed range. This paper presents a texture design on tool flank faces that can effectively generate process damping. A convex structure on the flank face dampens chatter vibration even at general cutting speeds. An orthogonal cutting simulation utilizing a finite element analysis was conducted to estimate process damping force coefficients that are the functions of cutting and vibration conditions and tool geometry. Sufficient damping effect was predicted using the proposed texture via a chatter stability analysis in frequency domain. Face turning experiments verified the significant chatter suppression effect.     

Chatter Stability of Metal Cutting and Grinding

This paper reviews fundamental modeling of chatter vibrations in metal cutting and grinding processes. The avoidance of chatter vibrations in industry is also presented. The fundamentals of orthogonal chatter stability law and lobes are reviewed for single point machining operations where the process is one dimensional and time invariant. The application of orthogonal stability to turning and boring operations is presented while discussing the process nonlinearities that make the solution difficult in frequency domain. Modeling of drilling vibrations is discussed. The dynamic modeling and chatter stability of milling is presented. Various stability models are compared against experimentally validated time domain simulation model results. The dynamic time domain model of transverse and plunge grinding operations is presented with experimental results. Off-line and real-time chatter suppression techniques are summarized along with their practical applications and limitations in industry. The paper presents a series of research topics, which have yet to be studied for effective use of chatter prediction and suppression techniques in industry.     

An investigation of in-process measurement of ground surfaces in the presence of vibration

Recent work on chatter in grinding has shown that the presence of torsional vibration is potentially significant. Controlling the torsional characteristics of the workpiece drive may eliminate chatter. These findings lead to a re-examination of the fundamental grinding force equation, where the surface speeds are conventionally assumed to be constant. If torsional vibration is present for both the grinding wheel and the workpiece, there will be two extra terms in the grinding force equation. Traditionally, experimental measurements used to try and verify the cutting force model have been undertaken under non-vibrating conditions. Any attempt to verify a cutting force model under vibrating conditions requires the continuous measurement of several parameters as a function of time. One of these is the instantaneous depth of cut, δ. This paper presents experimental results for an investigation into the in-process measurement of δ under chatter conditions on a cylindrical grinding machine. This initial investigation has indicated that such a measurement is very difficult and is prone to errors if chatter is present. It is proposed and anticipated that controlled (vibration) excitation under inherently stable conditions will allow for the required measurements to be made with sufficient accuracy.     

新型陶瓷托辊专用磨床磨削颤振稳定性分析

为了避免陶瓷托辊专用磨床在加工过程中产生颤振而降低磨削质量,根据陶瓷托辊磨削加工机制,建立了陶瓷托辊磨削加工过程数学模型,通过MATLAB计算分析得出磨削深度与主轴转速的稳定性叶瓣图,确定了陶瓷托辊磨床在磨削深度低于4 mm时可无颤振稳定磨削。研究结果为陶瓷托辊专用磨床稳定磨削加工提供了参考。     

Active chatter suppression in turning by band-limited force control

The suppression of chatter vibration is required to enhance the machined surface quality and to increase tool life. In this study, a new, conceptually active approach for chatter suppression in machining is proposed. The hybrid control method developed by applying sensorless force control with a disturbance observer enables the simultaneous and independent control of the position trajectory and band-limited forces. The proposed method is introduced to the carriage of a prototype desktop-sized turning machine, and the ability to suppress chatter is evaluated by end-face cutting tests. The results demonstrate that actively controlling a band-limited force leads to the avoidance of chatter.     

Optimization of Set-up Conditions for Stability of The Centerless Grinding Process

The stability of the centerless grinding process is very sensitive to the set-up conditions due to the uniqueness of the work-holding system. Centerless grinding produces precision components with high productivity only when the set-up condition is optimally chosen. This paper describes the effect of set-up conditions on three stability criteria of the centerless grinding system. It also presents guidelines for determining proper set-up conditions to avoid spinners, chatter vibration and roundness problems. Finally, an algorithm for providing the optimum set-up condition based on process aims is proposed and the simulation results are discussed.     

Increased productivity in centerless grinding using inertial active dampers

Regenerative chatter during centerless grinding processes is one of the main factors limiting the productivity. This paper presents a novel chatter suppression technique for centerless grinding using an active damping system based on inertial actuators. Dynamic characterisation of the machine with and without active damping is used first to compute theoretical stability maps. The active nature of the system allows stabilising a wide working range of infeed operations. Finally, experimental results validate the predicted increase of stable grinding area and verify that the technology is very effective for avoiding chatter, ensuring workpiece quality and increasing process productivity.     

The measurement of forces in grinding in the presence of vibration

Most investigations of chatter have made the assumption that torsional vibration is not a significant factor. Some recent work has shown that chatter in grinding is affected by a change in the torsional stiffness of the workpiece drive. Also, a theoretical model of grinding chatter has been developed that confirmed the significance of torsional effects. However, the model for the grinding force was assumed to be a dynamic equivalent of a published steady-state model. This paper describes tests conducted to measure the variation in force caused by an oscillation in workpiece speed. The oscillating test results indicate that the torsional vibration of the workpiece may well be a significant effect on chatter in grinding. Moreover, as the grinding force changes with workpiece speed, it may be possible to use variation of workpiece speed at high frequency to reduce chatter.