高精度无心磨削圆度保证和成圆过程解析

为了对无心磨削的圆度误差进行研究,讨论了影响高精度无心磨削过程的关键因素,包括稳定性、磨削参数、砂轮和导轮,给出了改进圆度误差的措施。在时域内对无心磨削成圆过程进行了解析。在解析研究中考虑了成圆过程的非线性环节,通过工件的轮廓和工件与砂轮、托板和导轮之间的作用研究工件的成圆过程。实验结果和理论结果的对比显示,解析模型可以对成圆过程进行准确预测。     

不规则零件的无心磨削

介绍了无心磨床磨削不规则零件时的特点,阐明了无心磨削不平衡零件及局部有缺口零件的加工精度（圆度）差的主要原因是由工件的跳动引起的,通过对各种不同重量、不同形状、不平衡量及不同缺口的各类零件的无心磨削的加工精度进行分析后,归纳出无心磨削不规则零件的磨削特点,所得到的解决此类零件的磨削方法以及磨削不规则零件的最佳磨削参数,可供技术人员参考。     

微小振动影响超精密非球面加工精度的研究

超精密磨削已广泛应用于轴对称非球面光学元件及硬脆材料的加工，加工过程中砂轮的不平衡量和机床主轴引起的振动直接影响工件表面精度及粗糙度。为了适应非球面工件超精密加工的要求，本文通过分析加工过程中产生的振动现象，建立磨削中振动引起工件表面轮廓误差的数学模型，研究主轴转速变化及磨削加工参数对工件表面精度的影响；通过建立工件与砂轮之间的运动关系，得出砂轮的振幅、频率及加工速度的变化对工件表面精度的影响条件。研究结果表明：选择合理的加工参数能降低工件表面波纹度，提高工件的表面精度。     

新型无心磨削技术研究及其在微细工件加工中的应用

提出一种用于微细工件加工的新型无心磨削技术。该技术采用超声椭圆振动板取代传统无心磨床中导轮,在加工中超声椭圆振动板和托板共同支撑和控制工件的运动。通过FEM优化设计超声振动板的结构;利用测试系统对其性能进行测试,确保超声振动板端面振动轨迹可以通过施加在PZT上的输入参数来控制;通过工件转速评价装置证实振动板端面超声椭圆振动能精确控制工件旋转速度。在改进后的无心磨床上对工件进行磨削实验,结果表明：硬质合金材料工件磨削后其直径为0.06 mm,长度为15 mm,长径比达到250,证实了该技术对微细工件加工的有效性。     

新型无心磨削技术研究及其在微细工件加工中的应用

提出一种用于微细工件加工的新型无心磨削技术。该技术采用超声椭圆振动板取代传统无心磨床中导轮,在加工中超声椭圆振动板和托板共同支撑和控制工件的运动。通过FEM优化设计超声振动板的结构;利用测试系统对其性能进行测试,确保超声振动板端面振动轨迹可以通过施加在PZT上的输入参数来控制;通过工件转速评价装置证实振动板端面超声椭圆振动能精确控制工件旋转速度。在改进后的无心磨床上对工件进行磨削实验,结果表明:硬质合金材料工件磨削后其直径为0.06 mm,长度为15 mm,长径比达到250,证实了该技术对微细工件加工的有效性。     

无心磨导轮的精密修整及其对磨削精度的影响

1、前言为了提高磨削精度,设定合理的微量磨削切深,并抑制其波动是十分重要的。无心磨削时,磨削切深的波动主要是由导轮周边与工件接触点的径向跳动所引起的,而导轮的径向跳动则又是由以下两个因素所引起的: (1)导轮轴的径向跳动。     

磨削用量对高速点磨削表面轮廓分布的影响研究

针对磨削用量对高速点磨削加工表面轮廓分布规律进行了试验研究,重点分析了点磨削倾斜角α=0.5°时磨削参数对加工表面粗糙度和轮廓分布的影响情况。通过统计表面偏态系数和峰态系数评价加工轮廓的分布状况,利用支承面积率和支承指数评价轮廓表面承载性能。研究发现,轮廓分布有利于获得良好的零件表面承载性和可靠性。在高砂轮转速、较小的进给速度和中等磨削深度时获得的点磨削表面质量更为理想。     

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各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进行分析探讨。     

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。     

无心磨削准动力学谐波生成机理

本文以包络理论为基础，建立了无心磨削的准动力学谐波生成机理。研究表明，在给定的系统振动频率下，合理地改变工件转速和调整几何布局参数，可以有效地控制工件磨削表面的谐波分布状态，计算机仿真结果与实验结果相一致。     

Simulation investigation of through-feed centerless grinding process performed on a surface grinder

This paper proposes a simulation method for investigating the through-feed centerless grinding process performed on a surface grinder, where a compact centerless grinding unit, composed of a guide plate, an ultrasonic elliptic-vibration shoe, a blade, and their respective holders, is installed onto the worktable of a surface grinder, and the through-feed centerless grinding operation is performed as the workpiece located on the guide plate is fed into the space between the grinding wheel and ultrasonic shoe. The geometrical arrangement of the grinding apparatus including the contact lines on the grinding wheel, ultrasonic shoe, and blade are analyzed firstly for building a 3-D simulation model. Then, the workpiece forming process and the effects of major process parameters such as the workpiece eccentric angle, the stock removal, the ultrasonic shoe tilt angle and the applied voltage amplitude on the machining accuracy (i.e. workpiece cylindricity and roundness) are clarified by simulation and experiments. The obtained results indicate that higher machining accuracy can be achieved under the conditions of larger workpiece stock removal, smaller ultrasonic shoe tilt angle and higher applied voltage amplitude, while the workpiece eccentric angle is at 6°.     

Wheel curve generation error of aspheric microgrinding in parallel grinding method

In aspheric grinding of hard brittle material, in-process wheel wear is a crucial factor affecting the profile error of the ground surface. To suppress wheel wear, parallel grinding is adopted. Since the wheel and workpiece contact point changes during parallel grinding, geometric wheel error influences machining accuracy significantly. In the wheel truing process with a cup truer, the wheel radius is determined by the angle and distance between the wheel and the truer. Through geometric analysis, this paper presents a new equation of wheel radius, which enables process parameters, such as setup error or thermal error, to be determined easily. Simulation results show that wheel radius error is predominantly affected by vertical deviation between the wheel rotation center and the truer center. Experimental results show that wheel radius errors match those from simulation well.     

A new through-feed centerless grinding technique using a surface grinder

This paper proposes an alternative centerless grinding technique, i.e., through-feed centerless grinding using a surface grinder. In the new method, a compact centerless grinding unit, composed of a guide plate, an ultrasonic shoe, a blade, and their respective holders, is installed onto the worktable of a surface grinder, and the through-feed centerless grinding operation is performed as the workpiece located on the guide plate is fed into the space between the grinding wheel and ultrasonic shoe. The ultrasonic shoe, produced by bonding a piezoelectric ceramic device onto a metal elastic body, is tilted at a small angle so as to provide sufficient force to control the workpiece rotational motion and to feed the workpiece along its axis by the ultrasonic elliptic-vibration. In this paper, the workpiece motion control tests were carried out firstly to make sure that the workpiece rotational speed and through-feed rate can be exactly controlled by the ultrasonic shoe which is essential for performing high-precision grinding operations. Then, the effects of major process parameters such as the workpiece eccentric angle, the stock removal, the ultrasonic shoe tilt angle and the applied voltage amplitude on the machining accuracy (i.e. workpiece cylindricity and workpiece roundness) were clarified experimentally. The obtained results indicate that: (1) the workpiece rotational speed can be adjusted by changing the applied voltage amplitude, whereas its through-feed rate can be adjusted by changing both the applied voltage amplitude and the ultrasonic shoe tilt angle; (2) the optimum eccentric angle is 6°, and a larger stock removal, a smaller tilt angle, or a higher applied voltage is better for higher machining accuracy; (3) the workpiece cylindricity and roundness were improved from the initial value of 16.63 μm and 14.86 μm to the final ones of 1.49 μm and 0.74 μm under the optimal grinding conditions.     

磨削对氧化膜去除质量影响的稳定性与敏感性

目的研究磨削参数对电化学加工氧化膜去除质量的影响规律,以及各参数对氧化膜去除质量影响的稳定性和敏感性。方法在试件表面形成均匀一致,无缺陷电化学加工氧化膜的前提下,借助自主搭建的机械磨削实验平台,分别研究磨粒尺寸、工件速度、磨削压强和加工时间对氧化膜去除质量的影响,使用精密电子天平和扫描电子显微镜对实验前后的试件进行测量,结合稳定性与敏感性分析理论对实验结果进行分析。结果不同的加工参数对氧化膜去除程度的影响不尽相同,氧化膜既存在不完全去除的现象,也存在完全去除的现象。扫描电子显微镜结果也显示,不同尺寸的磨粒对氧化膜的破坏程度不同,其表面氧化膜的沟槽深浅不同。结论受氧化膜硬度低、容易去除和基体金属硬度高、不容易去除的影响,氧化膜去除质量随着工件速度和加工时间的增加呈现三次曲线的规律增加,随磨削压强和磨粒尺寸的增大呈线性增加趋势。磨削参数对氧化膜去除质量影响的稳定性与敏感性不同,而且在电化学机械加工生产应用中不改变磨削工具,所以在磨削参数相对值较低的区间,其对去除质量影响的稳定性由大到小(敏感性由小到大)为:磨粒尺寸、加工时间、磨削压强、工件速度。在磨削参数相对值较高的区间,稳定性由大到小(敏感性由小到大)为:磨粒尺寸、磨削压强、工件速度、加工时间。加工中优先选择稳定性高(敏感性低)的参数作为调整电化学机械加工效果的主要因素,可在提升经济性的同时,提高加工精度。     

磨削硬化深度预测

磨削硬化是利用磨削过程中产生的热、机械复合作用直接对工件进行表面淬火的新工艺。通过建立磨削温度三维分析模型和热金属效应分析,实现磨削硬化加工工件硬度的预测。基于瞬时温度分布和运动非稳定三维热传导微分方程,并考虑砂轮与工件及冷却液与工件交互作用时热传导情况和材料本身的热扩散,建立了磨削温度三维分析预测模型,结合对加工过程奥氏体相位比例的计算及珍珠岩、残余奥氏体和马氏体的转变等热冶金效应分析,得出磨削硬化加工后硬化深度,实现随加工参数变化的硬化深度分布预测。将此模型与有限元模型进行对比,并通过实验进行了验证。     

GH4169镍基高温合金砂带磨削表面完整性分析

采用恒压力堆积磨料砂带磨削方法对GH4169镍基高温合金进行磨削,能够实现磨削过程的压力控制,减少磨削过程中切削力的变化对磨削特性的影响。通过正交实验法对镍基高温合金材料试件进行磨削实验,根据极差分析结果得到了材料表面粗糙度的最优磨削工艺参数。实验结果表明:当磨削压力为60 N、振动频率为1 Hz、砂带线速度为34 m/s时,表面粗糙度R_a为0.072 μm,达到最优值。同时,这也验证了该方法在磨削GH4169高温合金时的可行性,为生产中磨削参数的选择提供了实验依据。      

Effects of process parameters on workpiece roundness in tangential-feed centerless grinding using a surface grinder

The present authors proposed a new centerless grinding method using a surface grinder in their previous study [Wu, Y., Kondo, T., Kato, M., 2005. A new centerless grinding technique using a surface grinder. J. Mater. Process. Technol. 162–163, 709–717]. In this method, a compact centerless grinding unit composed mainly of an ultrasonic elliptic-vibration shoe is installed onto the worktable of a multipurpose surface grinder to perform tangential-feed centerless grinding operations. However, for the complete establishment of the new method it is crucial to clarify the workpiece rounding process and the effects of process parameters such as the worktable feed rate, the stock removal and the workpiece rotational speed on the machining accuracy, i.e., workpiece roundness, so that the optimum grinding conditions can be determined. In this paper, the effects of the process parameters on workpiece roundness are investigated by simulation and experiments. For the simulation analysis, a grinding model taking into account the elastic deformation of the machine is created. Then, a practical way to determine the machining-elasticity parameter is developed. Further, simulation analysis is carried out to predict the variation of workpiece roundness during grinding and to discover how the process parameters affect the roundness. Finally, actual grinding operations are performed by installing the previously constructed unit onto a CNC surface grinder to confirm the simulation results. The obtained results indicate that: (1) a slower worktable feed rate and higher workpiece rotational speed give better roundness; (2) better roundness can be also obtained when the stock removal is set at a larger value; (3) the workpiece roundness was improved from an initial value of 23.9 μm to a final value of 0.84 μm after grinding.     

An integrated model of tool grinding: challenges,chances and limits of predicting process dynamics

The objective of manufacturing technology, to reduce machining costs, increase product quality and optimize process setups, is only achievable by considering the entire manufacturing process and its interrelations. Especially in tool grinding, strong interactions exist between workpiece dynamics, grinding wheel engagement, structure deformations and cutting process conditions, which makes an integrated model necessary. This paper introduces a tool grinding model that combines time-dependent dynamical aspects of the grinding wheel and workpiece with local varying contact conditions to predict the final workpiece geometry and cutting forces with a high resolution in space and time. The model is capable to reproduce systemic effects on cutting forces and ground geometries which only occurs in the interplay of all system components. The model is also positively tested in representing influences of process parameters and in optimizing the machining. The excellent agreement of simulations and experimental data shows the model’s potential in manufacturing technology, but also in investigating grinding aspects, which are not fully understood yet.     

Modeling of minimum uncut chip thickness in micro machining of aluminum

Micro mechanical machining operations can fabricate miniaturized components from a wide range of engineering materials; however, there are several challenges during the operations that can cause dimensional inaccuracies and low productivity. In order to select optimal machining parameters, the material removal behavior during micro machining operations needs to be understood and implemented in models. The presence of the tool edge radius in micro machining, which is comparable in size to the uncut chip thickness, introduces a minimum uncut chip thickness (MUCT) under which the material is not removed but ploughed, resulting in increased machining forces that affect the surface integrity of the workpiece. This paper investigates the MUCT of rounded-edge tools. Analytical models based on identifying the stagnant point of the workpiece material during the machining have been proposed. Based on the models, the MUCT is found to be functions of the edge radius and friction coefficient, which is dependent on the tool geometry and properties of the workpiece material. The necessary parameters for the model are obtained experimentally from orthogonal cutting tests using a rounded-edge tool. The minimum uncut chip thickness (MUCT) is then verified with experimental tests using an aluminum workpiece.     

基于磨削力的磨削区表面温度场理论模型

为研究磨削热产生的机理、改善加工质量,从磨削力的角度,分析磨削工件表面温度并进行纯理论建模。将磨削力分为切削变形力和摩擦力2部分,分别研究其同加工参数的关系。计算切削变形力和摩擦力的切向分力,并结合切向分力同热源强度的关系,建立磨削表面最高温度的理论模型。通过磨削45号钢并进行测温实验,确定模型中的常数,进而确定模型。研究发现:工件表面温度随切深、进给速度和砂轮转速增大而增大;表面温度模型的理论值与实验值之间的最大相对误差为5.04%,平均相对误差为2.47%。证明此方法可用于磨削表面温度场分析,进而改善加工表面质量。