高速深磨磨削表面烧伤的实验研究

高速深磨磨削表面烧伤研究是高速深磨的非常重要的内容。文章通过测量40Cr钢高速深磨磨削试件表面烧伤层的深度,观察磨削表面质量,分析了高速深磨各种工艺参数对磨削烧伤层厚度的影响规律,研究了避免磨削烧伤和磨削裂纹的高速深磨磨削参数优化准则。     

The role of cooling in creep feed grinding

This paper concerns the thermal aspects of creep feed grinding, as contrasted to conventional grinding. The importance of adequate cooling in creep feed grinding is well known. Without cooling, the grinding temperature in creep feed grinding would be higher than in conventional grinding. Fortunately, coolant application has been seen to be very effective in reducing the grinding temperature in creep feed grinding. In fact, while cooling is more crucial in creep feed than in conventional grinding, it is also more effective in creep feed grinding.     

ELID磨削工艺参数对磨削力的影响

小口径非球面玻璃透镜因具有极高的成像质量和成像分辨率而被广泛应用于中高档镜头中。在线电解修整(Electrolytic In-Process Dressing,ELID)磨削作为高效的镜面磨削方法被广泛应用于硬、脆等加工材料的镜面磨削。在精密平面磨床上安装喷嘴电解ELID磨削系统对硬质合金材料进行了喷嘴电解方式ELID磨削试验研究。实验分析了磨削力随着砂轮转速、工作台进给速度、磨削深度三个磨削工艺参数变化的规律。同时,相同的磨削参数下,比较喷嘴电解方式ELID磨削和普通磨削的磨削力研究。试验结果表明,喷嘴电解方式ELID磨削能明显降低磨削力,与普通磨削相比较,能更好的实现硬质合金材料的超精密磨削加工。     

Experimental investigation of surface quality for minimum quantity oil–water lubrication grinding

Effective lubrication and cooling is necessary to ensure grinding temperature levels not to become excessive during grinding process. Conventional grinding fluid has negative influences on the working environment in terms of the health of the machine operator. Furthermore, the using of grinding fluid is seen to increase production cost due to fluid purchase and disposal. One attractive alternative is the minimum quantity lubrication (MQL) grinding. In this study, oil–water was applied in the MQL grinding and the grinding results were compared with those of wet, dry, and pure oil MQL grinding. It is found that MQL grinding in comparison to dry grinding significantly enhances grinding performance in terms of improving the quality of the ground workpiece and reducing grinding temperature and forces. Compared with pure oil MQL grinding, the grinding temperature and the thickness of the affected layer for oil–water MQL grinding are lower. However, the tangential force and surface roughness for oil–water MQL grinding are higher than that for pure oil MQL grinding. This indicates that the former has a better cooling condition than the latter, but the lubrication capacity is contrary.     

超高速磨削温度的实验研究

用人工热电偶方法对40Cr和45#钢的超高速磨削温度做了深入的实验研究.发现提高砂轮线速度,工件的磨削温度随之升高;但从某一速度开始继续提高砂轮线速度,磨削温度却呈明显下降的趋势.这就预示超高速磨削温度较低,适合磨削.同时对超高速磨削的比磨削能进行了研究,表明大切深超高速磨削是可行的,发现40Cr钢的超高速磨削性能优于45#钢.     

STUDY ON A NEW TYPE OF THROWAWAY SOFT GRINDING WHEELS

In accordance with the difficult problems of belt cross vibrations and effects of belt tension on machine spindle precision in abrasive belt grinding, a new soft grinding wheel is put forward, which is provided with the advantages of belt grinding and can be installed directly on the grinding machine spindle substituting for common grinding wheels. The new soft grinding wheel does not need any ancillary facilities and dressing devices in grinding. With analyzing error of wheel and grinding experiment, the highefficiency grinding characteristics grinding hardbrittle materials has been obtained.     

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.     

面齿轮磨削力建模与工艺影响分析

建立了碟形砂轮磨削面齿轮的理论模型.应用切斜面磨削理论,将不规则的曲面齿面等效转化为平面,结合Gleason点接触椭圆等特征,方便对磨削力进行分析求解.将砂轮上的工作磨粒数均匀划分成单颗磨粒成屑力与滑擦力个体,精确阐述砂轮在磨削面齿轮时的磨削力.经过实验结果与仿真数值的比照分析得到磨削力对磨削用量的影响参数,实验结果表明,砂轮转速与面齿轮磨削力成反比例关系,工件进给速度与磨削速度与面齿轮磨削力成正比例关系.通过磨削力的实验结果与仿真数值对比分析,可得出最大相对误差为１７.９％,此数据证明了建立的模型与实验结果较为契合,能够很好地反映磨削力与磨削用量之间的关系变化,在提高面齿轮磨削精度与工艺上提供了基础的理论依据.     

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。     

钢轨砂带打磨与砂轮打磨综合性能对比实验研究

基于自主研发的锂电驱动钢轨砂带打磨机和砂轮打磨机,以60N型钢轨廓形作为实验对象,全面对比了新型钢轨砂带打磨技术和传统砂轮打磨技术的性能。结果表明：当打磨压力在45～75 N范围内时,砂带打磨的材料去除率约为砂轮打磨的15～30倍,而当压力增大到90 N时,砂带打磨的材料去除率高达砂轮打磨的102倍;砂带打磨的振动加速度、噪声和能耗均小于砂轮打磨;砂带打磨切屑为带状,而砂轮打磨则表现为高温熔融状,同时当打磨压力增大到105 N时,砂轮打磨后钢轨表面会出现发蓝现象,而砂带打磨不会;此外,砂带打磨的横向表面粗糙度大于砂轮打磨,最高可达8 μm,但满足中国铁路钢轨养护要求的最大值10 μm。综上,钢轨砂带打磨技术在材料去除率、振动、噪声、能耗和温度等方面显著优于传统砂轮打磨技术,预期将成为工程实际中解决钢轨严重病害问题的有效方法之一。     

细粒度金刚石砂轮超精密磨削硅片的表面质量

为实现硅片高质量表面的超精密磨削，研究了5000目、8000目和30 000目金刚石砂轮磨削硅片的表面质量。利用数学模型预测了硅片磨削表面的粗糙度Ra并对预测结果进行了试验验证，分析了硅片磨削表面的形貌特征；通过磨床主轴电机的电流变化对比分析了5000目、8000目和30 000目砂轮磨削过程中的磨削力变化趋势。研究结果表明：8000目砂轮磨削后的单晶硅表面粗糙度Ra小于10 nm,亚表面损伤深度小于150 nm,磨削过程中的磨削力稳定，磨削质量优于5000目砂轮，磨削过程的稳定性优于30 000目砂轮。     

新型点磨削砂轮磨削力模型及试验研究

点磨削砂轮轴线与工件轴线之间存在倾斜角α,磨削过程中磨粒的运动轨迹改变,点磨削力及理论模型也随之变化。以传统磨削力理论为基础,利用点磨削模型的转换,建立点磨削力理论模型,通过试验验证理论模型的正确性。试验结果表明:模型的计算值与试验结果的趋势一致,数值相近。点磨削力模型为实际加工提供一种辅助和验证方法。同时提出一种带有粗磨区倾角θ的新型点磨削砂轮,在点磨削力模型的基础上,做了进一步研究,建立新型砂轮的磨削力分配模型。通过点磨削试验对该模型进行试验验证,用不同θ角的砂轮在一系列磨削参数条件下磨削阶梯轴。试验表明:模型分析结果与试验结果一致,在相同磨削参数下,带有粗磨区倾角θ的新型点磨削砂轮的磨削力要小于θ=0°的传统点磨削砂轮磨削力,磨削力随着θ角的增大而减小。此外,还可以得出磨削参数倾斜角α、磨削深度ap和砂轮速度vs对点磨削力的影响规律。     

工件横向施振超声振动磨削力特性试验研究

基于冲量理论和振动加工理论,采用叠加原理建立了工件横向施振超声振动磨削力数学模型。从理论上解释了工件横向施振超声振动磨削力低于普通磨削力的原因,并进行了超声振动与普通磨削力对比试验研究。结果表明:超声振动磨削力比普通磨削力减小20%~30%,磨削力的大小随工作台进给速度的提高而减少,磨削深度的增加而增大,当达到某一临界切深时,磨削力急剧下降。磨削力可做为评价陶瓷材料脆延转变的一个重要参数。     

Force Characteristics in Continuous Path Controlled Crankpin Grinding

Recent research on the grinding force involved in cylindrical plunge grinding has focused mainly on steady-state conditions.Unlike in conventional external cylindrical plunge grinding,the conditions between the grinding wheel and the crankpin change periodically in path controlled grinding because of the eccentricity of the crankpin and the constant rotational speed of the crankshaft.The objective of this study is to investigate the effects of various grinding conditions on the characteristics of the grinding force during continuous path controlled grinding.Path controlled plunge grinding is conducted at a constant rotational speed using a cubic boron nitride(CBN)wheel.The grinding force is determined by measuring the torque.The experimental results show that the force and torque vary sinusoidally during dry grinding and load grinding.The variations in the results reveal that the resultant grinding force and torque decrease with higher grinding speeds and increase with higher peripheral speeds of the pin and higher grinding depths.In path controlled grinding,unlike in conventional external cylindrical plunge grinding,the axial grinding force cannot be disregarded.The speeds and speed ratios of the workpiece and wheel are also analyzed,and the analysis results show that up-grinding and down-grinding occur during the grinding process.This paper proposes a method for describing the force behavior under varied process conditions during continuous path controlled grinding,which provides a beneficial reference for describing the material removal mechanism and for optimizing continuous controlled crankpin grinding.     

基于磨削痕迹仿真的磨削纹理生成机理

针对球面和非球面垂直磨削法加工中出现的磨削纹理，开展了基于磨削痕迹轨迹仿真的磨削纹理生成机理研究，建立了磨削痕迹运动分布方程，仿真分析了磨削痕迹在垂直磨削表面的生成和分布机制，揭示了磨削加工参数变化引起的磨削纹理生成机理。通过仿真结果可以看出，垂直磨削后的工件表面残留磨削痕迹分布为中心区域密集、外缘区域稀疏，并具备周期性、放射分布的特征；砂轮圆周上参与磨削的磨粒残留在工件表面的磨削痕迹长度、形状和分布规律几乎完全相同，磨削痕迹间仅存在一定的相位偏差；砂轮与工件的转速比为整数时，相邻螺旋周期的破碎磨削痕迹首尾相接，使得磨削痕迹交接处发生了破碎的耦合与扩展，加剧了工件表面的破碎，并将破碎的磨削痕迹连接在一起，形成磨削纹理。     

6061-T651铝合金单颗磨粒磨削仿真

通过简化并建立单颗磨粒磨削模型,采用ANSYS LS-DYNA进行对6061-T651特种铝合金磨削过程的理论研究和仿真分析,总结了单颗磨粒的磨削速度、磨削深度等工艺参数对磨削力大小以及磨屑的影响。研究表明:随着磨削速度的增加,单个磨料颗粒的磨削力减小,并且递减速率呈先增大后减小的趋势;而磨削深度的增加则会使单个磨料颗粒的磨削力增大,且递增速率逐渐减缓。磨削过程中,磨屑形状受加工参数的影响,其中,磨削深度对磨屑形状的影响比磨削速度对磨屑形状的影响更大。     

40Cr钢高效深磨磨削力试验研究

通过对40Cr钢在高效深磨条件下磨削力的试验研究,分析了不同工况对磨削力变化的影响,提出了40Cr钢高效深磨工艺参数的优化方案。试验结果表明:40Cr钢在高效深磨条件下,磨削力随磨削深度的变化呈波浪式起伏的非线性关系,随砂轮线速度的提高而明显减小,同时能获得比普通磨削大得多的比材料磨除率,以及较好的工件表面质量。     

Experimental investigation of contact behaviour in grinding

The nature of the wheel and workpiece contact in grinding has a strong effect on the temperature, force and surface integrity as well as wheel wear in grinding. An applied power source method was used to measure the real contact length. The interpretation of contact length measurements is discussed. Experimental measurements of contact length in grinding show that the contact length is much larger than the geometrical contact length. This difference is most significant in fine grinding and in the sparkout stage of plunge grinding. The difference also increases when the table speed is increased. The contact length in wet grinding is longer than the contact length in dry grinding. The contact length when grinding cast iron is shorter than the contact length when grinding mild steel. It is found that grinding geometry, grinding force and the roughness of the grinding wheel have independent effects on the contact length. The newly developed contact length model by the authors describes these effects quantitatively. These results also show the importance of the roughness factor, R_r, for analysis of the contact behaviour in grinding processes.     

切入磨削与纵向磨削的磨削力分析与比较

研究了同时包含切入磨削和纵向磨削的复杂外圆磨削过程。根据纵向磨削过程的特点,将砂轮等效成若干个小砂轮,在传统阶梯模型的基础上构建了砂轮磨损的抛物线模型。推导了基于两种模型的纵向磨削切向分力和切入磨削切向分力的比较公式,两切向分力的比值反映了切入磨削和纵向磨削转换时切向分力的变化情况,它主要与磨削系数、砂轮宽度和纵向进给速度有关。采用砂轮主轴功率信号分析磨削切向分力,通过实验验证了抛物线模型更符合实际情况的结论。研究结果为采用磨削力信号和功率信号研究复杂磨削过程的监控提供了参考依据。     

铁氧体陶瓷高效磨削技术研究

通过试验研究了不同磨削参数对铁氧体的表面粗糙度、磨削力、磨削效率的影响规律,并在此基础上探讨了铁氧体的高效磨削技术。