基于修整力的树脂结合剂金刚石砂轮机械修整

研究了树脂结合剂金刚石砂轮修整过程中修整力与修整效果的关系,基于修整力的变化表征了砂轮的表面形貌及磨削性能。首先,对碳化硼、碳化硅、白刚玉3种砂轮修整工具进行实验,并采集了修整过程中修整力的变化;然后,利用白光干涉仪观测修整后砂轮的表面形貌;最后,对修整后砂轮进行磨削验证实验,得到不同修整工具修整后砂轮的磨削性能。基于上述实验,分析并验证了修整力的变化与砂轮表面形貌和砂轮磨削性能的关系。结果表明,法向力Fn能够表征砂轮的磨粒切削刃密度以及磨粒突出高度;修整比率β反映了砂轮的锋锐程度,当β稳定时,砂轮达到充分修整。因此修整力反映了砂轮表面形貌和磨削性能,根据修整力的变化可以把握砂轮的修整进程。     

螺旋曲面数控成型磨削与砂轮修整控制研究

提出了一种螺旋曲面磨削加工和砂轮修整控制与协调问题的新方法，解决了砂轮修整时砂轮廓形数据的更新、砂轮半径的补偿等问题。     

CBN砂轮超声振动修整试验研究

对金刚石笔辅助超声振动修整法修整CBN砂轮进行试验研究。试验结果表明超声振动修整对调节砂轮表面形貌非常有效。振动修整的砂轮,其表面静态有效磨粒数多于普通修整,磨粒特征亦优于普通修整,并且不同超声频率修整条件下,砂轮表面静态有效磨粒数随着修整导程的增加而减少,随修整切深的增大呈下降趋势。选择合理的参数,采用超声振动修整,可以实现CBN砂轮的精密修整。     

Study on the rotary cup dressing of CBN grinding wheel and the grinding performance

A systematic research is conducted to investigate the effect of rotary cup dressing on vitrified cubic boron nitride grinding performance in grinding of nickel-based superalloys. Grinding performance is evaluated mainly in terms of specific grinding energy and radial wheel wear. The number of active grits per unit area and their slope is considered as the two grinding wheel topographical key parameters for studying grinding performance. Cup dressing conditions with various speed ratios and overlap factors were investigated. In each case, the specific grinding energy and the radial wheel wear were experimentally measured, and then the effect of changing dressing parameters on the grinding performance is analyzed. To provide a view on how various parameters influence specific energy and the importance of wheel topography and grit workpiece interaction, a new specific grinding energy model is developed. Inputs to this model are workpiece parameters, grinding process parameters, and, in particular, the grinding wheel topographical parameters. This model is validated by experimental results. The theoretical values considering the complexity of the grinding process reasonably compare with the experimental results. The effect of number of active grits per unit area and their slope on specific grinding energy and then metal removal mechanism is investigated. The results revealed that the number of active grits per unit area has less effect on specific grinding energy than grits slope.     

Evaluation of wheel life by grinding ratio and static force

A degree of sharpness in wheel grains affects the surface roughness and dimensional accuracy in the grinding process. If a wheel with dull grains is used, the grinding force is increased and the surface roughness is deteriorated. In ovder to produce a precision component economically, the magnitude of the wear amount in the grinding wheel has to be limited. In this study, experimental evaluation of a wheel life varying with the grinding ratio and static grinding force was conducted. The grinding ratio and grinding force were measured to seek the grinding performance of the WA wheel. The relationship between the grinding ratio and static grinding force was presented.     

高速钢材料的粗金刚石砂轮轴向进给数控磨削机理研究

根据正交试验确定了影响高速钢材料的粗金刚石砂轮轴向进给数控磨削表面粗糙度值Ra的最主要因素是进给速度Vf.在此基础上,进行进给速度Vf单因素数控磨削实验,对数控磨削后表面粗糙度值进行了分析.     

转子磨床CNC砂轮修整器的砂轮初始修形方法研究

采用CNC砂轮修整器使复杂螺旋面工件的精密磨削成为可能,利用CNC砂轮修整器对新砂轮进行初始修形是砂轮修整的关键步骤.提出了3种砂轮的初始修形方法,对比了各自的优缺点,为CNC砂轮修整器的初始设计提供了理论基础,为用户实际加工提供了操作依据.     

螺纹磨床CNC砂轮修整器的参数设计

CNC砂轮修整器是螺纹磨床的关键部件,其结构参数的设计在满足传统设计的同时,必须考虑砂轮修型的自动化要求。综合考虑修整器的结构设计和后续砂轮修型程序编制的可操作性,本文设计了一种CNC砂轮修整器的结构及砂轮的修型方法,针对修整器工作时两个方向工作行程的特殊性,提出了相应参数的设计方法。     

Experimental study of wheel wear in electrolytic in-process dressing and grinding

Profile accuracy of components ground with ultra-precision machine tools is primarily dependent on wheel wear. Quantitative analysis of wheel wear is therefore an important aspect for precision grinding with electrolytic in-process dressing (ELID). In this paper, wheel wear is measured from ELID grinding experiments with different dressing and machining parameters. The grinding forces and dressing current characteristics of the experiments are also compared. Based on the results, a benchmark function is defined for wheel wear rate. A relation for identifying insufficient dressing from sufficient dressing for particular machining conditions is also identified. It is found that insufficient dressing produces pitting and/or arcing on the wheel surface, and wheel wear can be linearly correlated to ELID grinding conditions when the wheels are sufficiently dressed.     

声振动修整砂轮系统的阻抗分析

通过合理划分超声振动修整系统,计算出超声振动修整砂轮系统的各个子系统机械阻抗,运用机械阻抗综合法求出系统的共振频率,为实验中寻求系统的谐振点提供了理论依据.并且提出修整瓦的尺寸对系统的谐振频率影响不大,从而简化修整瓦的设计.     

成形磨齿砂轮修形插补节点数最优解

成形磨齿的齿形精度是由成形砂轮的修形精度来保证的,某型成形磨齿机利用A轴和W轴的极坐标运动来进行砂轮修整,即用阿基米德螺旋线来插补齿形的渐开线部分。为保证修形精度,需要一定的插补节点数来满足插补时的误差要求。为提高数控系统插补计算执行效率,首先根据啮合原理和插补原理进行理论计算,得到插补曲线与齿形渐开线的法向误差;当给定允许误差时,反求出满足该齿形误差的最少插补节点数。此节点数即为插补最优解;最后给出计算实例。     

Influence of dressing of the wheel on the surface quality of titanium alloy in deep grinding

The surface relief formed in deep grinding of VT8 titanium-alloy blanks with and without constant dressing of the grinding wheel is considered. Microphotographs of characteristic sections are shown, and the results of chemical analysis are presented.     

Numerical simulation of single-pulse laser ablation for dressing a bronze-bond diamond grinding wheel

To investigate the interaction between a laser beam and the bronze substrate in pulsed laser dressing of bronze-bonded diamond abrasive grinding wheels, a two-dimensional, transient numerical model of the three-phase (solid–liquid–gas) coupling in single-pulse laser ablation of the bronze was developed. The model accounts for the heat transfer, solidification, melting and vaporisation processes; the latent heat mechanism of the phase changes; and various critical factors such as surface tension, the vaporisation-induced recoil force, the thermal buoyancy force, and Darcy friction. The phase-field method is used to accurately track the development of the liquid/vapour (L/V) interface in the ablation crater. The finite element analysis software COMSOL Multiphysics was used to calculate the internal temperature field of the bronze substrate, the velocity field in the metallic vapour zone, and the evolution of the shape of the ablation crater during single-pulse laser ablation with various average laser power levels. The maximum error between the experimental results and the numerical analysis was less than 5%, which shows that the results are consistent. This model can accurately simulate the dynamic behaviour of the crater L/V interface during single-pulse laser ablation. This study provides a theoretical foundation for further research on laser dressing technology for bronze-bonded diamond grinding wheels.     

A novel technique for dressing metal-bonded diamond grinding wheel with abrasive waterjet and touch truing

The dressing of metal-bonded diamond grinding wheels is difficult despite their availabilities on hard and brittle materials. In this paper, a novel compound technology that combines abrasive waterjet (AWJ) and touch truing is proposed for dressing metal-bonded diamond grinding wheel precisely and efficiently. The dressing experiments of a coarse-grained and a fine-grained bronze-bonded diamond grinding wheel were carried out on a surface grinder with a developed AWJ system. The feasibility of this method was verified by analyzing the wheel runout, the truing forces, and the wheel surface topography. The variations of 3D surface roughness of wheel surface topography during the compound dressing process were quantitatively analyzed. The mechanism of AWJ and touch compound dressing is also discussed. Further, a reaction-bonded silicon carbide block was ground to validate the dressing quality. The experiment results indicate that the grinding wheels that were well dressed by the proposed technique leads to a smaller grinding force and a smaller surface roughness than that of undressed wheels.     

3MB2030DZ磨床增加砂轮光修程序改进

为提高轴承内圈内孔的加工精度,对3MB2030DZ半自动球轴承内孔磨床砂轮修整PC程序进行了改进设计。     

A grinding force model allowing for dulling of abrasive wheel cutting grains in plunge cylindrical grinding

A mathematical model is developed for the grinding force in cylindrical plunge grinding that allows for the grinding conditions, the size of the flank wear land areas formed on the grinding wheel cutting grains, the properties of the work material, and the geometrical parameters of the grinding tool and work surface. A formula is obtained for calculating the stock removal rate as a function of the degree of dulling (glazing) of the grinding wheel. The adequacy of the mathematical model of the grinding force in cylindrical plunge grinding is established.     

On-machine precision preparation and dressing of ball-headed diamond wheel for the grinding of fused silica

In the grinding of high quality fused silica parts with complex surface or structure using ball-headed metal bonded diamond wheel with small diameter,the existing dressing methods are not suitable to dress the ball-headed diamond wheel precisely due to that they are either on-line in process dressing which may causes collision problem or without consideration for the effects of the tool setting error and electrode wear.An on-machine precision preparation and dressing method is proposed for ball-headed diamond wheel based on electrical discharge machining.By using this method the cylindrical diamond wheel with small diameter is manufactured to hemispherical-headed form.The obtained ball-headed diamond wheel is dressed after several grinding passes to recover geometrical accuracy and sharpness which is lost due to the wheel wear.A tool setting method based on high precision optical system is presented to reduce the wheel center setting error and dimension error.The effect of electrode tool wear is investigated by electrical dressing experiments,and the electrode tool wear compensation model is established based on the experimental results which show that the value of wear ratio coefficient K’ tends to be constant with the increasing of the feed length of electrode and the mean value of K’ is 0.156.Grinding experiments of fused silica are carried out on a test bench to evaluate the performance of the preparation and dressing method.The experimental results show that the surface roughness of the finished workpiece is 0.03 μm.The effect of the grinding parameter and dressing frequency on the surface roughness is investigated based on the measurement results of the surface roughness.This research provides an on-machine preparation and dressing method for ball-headed metal bonded diamond wheel used in the grinding of fused silica,which provides a solution to the tool setting method and the effect of electrode tool wear.     

螺纹磨床CNC砂轮修整器设计与修型方法研究

CNC砂轮修型的初始修型是砂轮修整的关键,本文以SK7450螺纹磨床CNC砂轮修整器为例,分析并介绍一种新的砂轮修型方法。该方法操作简便,适应面广。     

Effects of dressed wheel topography on patterned surface textures and grinding force

The camshaft is a crucial component of an engine’s valve train. This paper devotes to the experimental studies of the performance of laser surface textured (LST) camshaft. The first part experiment was carried out on the block-on-ring tester to investigate the tribological behaviors of textured surface in line contact. The area density of the textured dimples was in the range 3–40% with depths 5–24 μm and diameter 70 μm. The friction coefficient and wear tracks were analyzed to confirm the optimum textured patterns. After that, the local LST cams (textured on the lifting region) were further tested in a single-cylinder diesel. It was found that after 300 h durability test at the rated speed and load, the total lifting loss of cams decreased nearly 34.4% in maximum. In addition, the performance of the engine was not affected evidently. The enhanced lubricity and local hardening were two mechanisms for highly promoting the anti-wear property of the LST cams.