陶瓷结合剂金刚石砂轮的修整研究(Ⅱ)——杯形砂轮修整器的修整性能

本文详细讨论了杯形砂轮修整器修整陶瓷结合剂金刚石砂轮时的性能。主要结果如下:(1)修整器以横向进给方式修整时,金刚石砂轮断面形状为一斜线。使用其它修整器时,只要以横向进给方式进行修整,所得断面形状亦为一斜线。(2)修整器以切入送进方式修整时,只要把修整器旋转轴线调整到垂直于工作台面,则金刚石砂轮断面形状为一水平直线。若把旋转轴线调整到同工作台面成非90°夹角,则断面形状为一圆弧线或者斜线。(3)以切入送进方式修整时,金刚石砂轮速度越低或工作台速度越高,修整比越高。杯形砂轮旋转速度对修整比没有明显影响。(4)金刚石砂轮速度过快容易使砂轮表面磨粒钝化。     

数控成型磨床砂轮修整器的设计

分析评价了目前使用的修整渐开线、三角形、直齿花键等形状的两轴联动数控修整器,介绍了研制开发的一种新的数控成型砂轮修整器。详细介绍了采用尖端具有过渡圆弧的金刚石修整器的结构及特点优势。总结出简化成形砂轮修整的编程过程,避免了复杂的数字控制和软件计算分析,同时可以降低修整器的制造成本,可为数控成型磨床砂轮修整方案设计提供参考。     

砂轮修整工具用金刚石的性能研究

对用作修整工具的金刚石而言,天然大单晶价格高昂,修整接触面不稳定,使用过程中需要翻修。近年来,修整工具的制造商们在不断开发它们的替代产品。本文对S i-Ti-B系粘结相,WC-Co粘结相聚晶金刚石,及CVD金刚石对其微观结构进行SEM分析;并分别对样品加热500℃、800℃,测其磨耗比,进行耐磨性和耐热性分析;并制作成修整工具修整P400×50×100WA46NV535M/s砂轮,做使用性能对比实验。研究结果表明:(1)CVD金刚石的耐磨性能和耐热性最好;(2)中等粒度PCD的耐磨性、耐热性和抗冲击性等综合性能更好,更适合制作砂轮修整工具;(3)可选用不同截面尺寸和数量的条状金刚石,来增加修整工具的适应性。     

砂轮修整器安装高度误差对成型砂轮修整精度的影响

本文分析了回转曲面砂轮修整时，砂轮修整器安装高度误差对修整后砂轮截面形状精度的影响，分析结果表明：在两轴插补修整时，修整后砂轮半径的误差与砂轮修整器安装高度误差的平方成正比，与两者中心距的水平投影成反比，在实用范围内，此误差很小；在三轴联动修整时，修整后砂轮半径的最大误差等于两轴插补修整时误差的1．3倍左右；而砂轮截面形状误差更小。     

D杯形砂轮修整碟形金刚石砂轮试验研究

本文采用了D杯形砂轮与碟形砂轮对磨法来修整大直径树脂结合剂碟形金刚石砂轮。在分析研究杯形砂轮修整碟形砂轮的修整原理及修整方式的基础上，用自行研制的专用修整装置，从主轴转速、修整深度、修整工具结合剂类型等方面进行了对比工艺试验研究，总结了杯形砂轮修整碟形砂轮的不同工艺参数与修整效率、修整质量之间的工艺规律。试验结果表明，在本试验条件下主轴转速500r／min，修整深度0．02mm的修整效率较好；细粒度、中等浓度的青铜结合剂杯形金刚石砂轮与粗粒度、高浓度的杯形砂轮修整碟形砂轮相比，后者具有较好的修形效果和修整效率；D杯形砂轮与GC杯形砂轮交替配合使用可以大大提高碟形金刚石砂轮的修形效率和修锐效果。     

CVD金刚石砂轮修整工具应用研究

CVD金刚石具有很高的热导率、良好的热稳定性和极高的耐磨性,非常适合制作砂轮修整工具;本文通过砂轮修整试验研究了在CVD金刚石砂轮修整工具应用过程中,修整导程、CVD金刚石修整截面面积和CVD金刚石磨耗比等对其使用寿命的影响.研究结果表明,在保证砂轮的锋利度的情况下,使用较小的修整导程,可以延长修整工具的使用寿命;增大CVD金刚石的修整截面面积,有利于提高修整工具的寿命,但修整截面过大,砂轮的锋利度会降低;CVD金刚石的磨耗比对修整工具寿命没有明显影响,但修整效果有明显区别.在实际应用过程中,要根据所修整的砂轮的类型和修整要求,选用适当的修整参数,使CVD金刚石修整工具发挥其最佳作用.     

先进光学磨削中杯形修整技术开发及应用

对于金刚石砂轮修整,尤其是有高精度要求的圆弧金刚石砂轮,杯形砂轮修整技术可以获得较好的砂轮磨削性能以及修整效率。本文开发了配套超精密平面磨床使用的杯形修整器,分析了其机械误差影响,并完成了修整实验及砂轮表面测量及半径拟合处理,从宏观上考察了该修整器对砂轮磨削性能的提高,结果证明该修整器可以进行有效修整,提高了加工工具精度,能满足金刚石砂轮修整使用要求。     

超硬磨料砂轮不同介质中电火花修整试验研究

超硬磨料砂轮的电火花修整受到极间放电间隙的限制,采用传统的放电介质条件难以达到粗粒度砂轮的修整要求。为此,结合混粉放电加工机理,提出混粉介质中的电火花修整方法,进行压缩空气、去离子水雾和混粉去离子水雾3种介质及不同放电参数下的放电间隙对比试验研究,并开展金刚石砂轮修整和工件磨削试验。试验结果表明:混粉介质电火花修整的放电间隙最大,能提高粗粒度青铜结合剂金刚石砂轮的修整效率,同时优化砂轮修整后的表面形貌、磨粒突出状况和磨削性能。在开路电压为90 V、峰值电流为13.33 A及占空比为50%的最佳放电参数下,混粉介质的电火花修整效率与前2种介质相比可提高28.2%～50.0%;且加入的SiO₂粉末使砂轮表面的Si元素分布更均匀、含量更高,进而提高其耐磨性。      

一种固定式砂轮修整器的设计与分析

砂轮修整器是磨床使用中的关键部件,其结构要求在满足修整砂轮要求的同时,还应考虑到金刚滚轮的更换以及修整器通用性、功能性的提升。综合考虑修整器的结构和使用过程,设计一种固定式的、既安装金刚滚轮又安装成型滚轮的修整器,在增强其功能性的同时,充分考虑到滚轮的更换问题,提出了合理的方案。     

曲轴圆角的误差分析及砂轮修整器的改进

通过详尽的计算和分析,发现用原来的砂轮修整器修整出来的砂轮不能加工出满足圆颖中曲轴圆角的要求。在此基础上,给出了较为合理的砂轮修整器的具体样式。     

A novel laser-assisted truing and dressing technique for vitrified CBN wheels

The preparation of vitrified CBN or diamond wheels by truing and dressing has a large influence on the grinding performance. A worn diamond dresser cannot produce sufficient protrusion of cutting grain edges. To reduce the wear of diamond dressers and hence guarantee a desired wheel surface, a novel truing and dressing method, namely, laser-assisted truing and dressing, is proposed and tested to achieve good dressing quality and efficiency. A systematical experimental feasibility study on this newly proposed laser-assisted truing and dressing technique is conducted by investigating truing efficiency, truing accuracy, dresser wear, dressed wheel profiles, and specific forces in comparison with those of the conventional single diamond methods. Experimental results show that the new laser-assisted truing and dressing technique offers a number of advantages over the conventional single-tip diamond dressing and truing method. In addition, the underlying mechanism of the laser truing and dressing process is investigated through the careful analysis of the properties of chips and the microscopic structural characteristics of wheels.     

Wear of diamond dresser in laser assisted truing and dressing of vitrified CBN wheels

The rapid wear of diamond dressers in truing and dressing of vitrified CBN wheels remains an unsolved problem, and significantly affects the grinding performance of dressed wheels. Through combining laser-induced thermal effects into the process, laser assisted truing and dressing opened a new avenue for reducing the wear rates of diamond dressers. In this study a systematical investigation on the wear properties of diamond dressers in the novel laser assisted truing and dressing has been conducted, including (1) a theoretical analysis of some underlying items in the process of laser irradiation, (2) an experimental investigation of wear rates in the laser assisted truing and dressing, and (3) influences of the HAZ (heat affected zone) left by the last pass of laser assisted dressing. Experimental results show that the wear ratios of diamond dressers in the laser assisted dressing depend on laser power, depth of cut, and feed rate. Moreover, the heating history also has some impact on the wear ratios of diamond dressers.     

旋转金刚石修整工具修整超硬磨料砂轮的研究

本文对比研究了金刚石修整笔和旋转金刚石修整工具,在修整超硬磨料砂轮时修整力、工具磨损、修整效率等参数的变化规律,结果表明:超硬磨料砂轮的修整中,旋转金刚石修整工具修整力、修磨效率和磨损等几乎不随修整次数增加发生变化,其原因是修整工作是由整个圆周上金刚石分担,旋转型金刚石修整工具在修整过程中,具有挤压砂轮的作用,使被修整的金刚石砂轮表面具有较好锋利度.结果表明:在优化的修整工艺条件下,旋转金刚石工具可以实现对超硬磨料砂轮的精密修整.     

An experimental investigation of dry-electrical discharge assisted truing and dressing of metal bonded diamond wheel

Metal-bonded diamond wheels have superior qualities such as high bond strength, long wheel life, wear-resistant ability and high grinding efficiency. But it is very difficult to true and dress diamond wheel because of its highest hardness. Traditional mechanical truing does not guarantee truing accuracy of diamond wheel because of single diamond dresser wears out very quickly. To reduce wear of diamond dresser and hence guarantee a desired wheel surface, a novel truing and dressing method, namely, dry electrical discharge (dry-ECD) assisted truing and dressing, is proposed and tested to achieve good dressing quality and efficiency. Because the diamond wheel is mounted on the MK9025 optical profile grinder, dielectric liquid is forbidden. The new dry-ECD dressing/truing method basically eliminates the use of dielectric liquid. Therefore, it is free from the serious problem of electrolytic corrosion caused by electrolytic current flowing through water encountered in conventional ECD. The FE analysis of temperature distribution in dry-ECD assisted truing and dressing diamond wheel using ANSYS is performed in this study. Temperature field simulation helps to select optimized parameters under certain conditions. Energy dispersive X-ray (EDAX) analysis was used to measure the composition of diamond wheel before and after dry-ECD assisted truing and dressing. Further, hard alloy grinding experimental results proves that a little variation in material composition of diamond wheel after dry-ECD assisted truing and dressing does not influence grinding result. A series of experiments of dry-ECD assisted truing and dressing of metal bonded diamond wheel are conducted to investigate truing efficiency, truing accuracy, dresser wear, dressed wheel profiles and three-dimensional truing/dressing forces in comparison with those of the conventional single diamond methods. Experimental results show that the new dry-ECD assisted truing and dressing technique offers a number of advantages over the conventional single-tip diamond dressing and truing method. Furthermore, mechanism of the dry-ECD assisted truing and dressing is investigated through the careful analysis of the properties of chips.     

人造金刚石修整刀的研发

通过测量金刚石晶体与耐磨性之间的相关性发现,尽管在现行修整刀中常见的修整方向为(100)<110>方向,但是修整刀的最佳方向却是(110)<110>方向或者(211)<111>方向.根据这些成果,我们研制开发了一种新型修整刀.该新型修整刀的金刚石刀刃为条状,端面为(110)或者(211).其修整性能在耐磨性和稳定性方面...     

Grinding and electrochemical properties of diamond dresser fabricated in a combination technique

This study introduces surface-modified diamond grits embedded into nickel micro-prominences via micro-fabrication and nickel electroforming to fabricate novel diamond dressers. Two kinds of diamond dressers with micro-columnar prominences and micro-hemispherical prominences, denoted as CPD and SPD, respectively are characterized and compared with a commercial dresser, BSD. Among them, CPD has the lowest height level of the diamond grits and the diamond height leveling is most uniform due to the columnar shape of the nickel micro-prominences. Therefore, CPD has the highest weight loss of the counterpart and the lowest diamond worn of the diamond dresser by wear tests. In addition, CPD and SPD have a higher corrosion resistance than BSD. The reason is that the nickel deposition has a higher corrosion resistance than the Ni-based alloy in chemical-mechanical-polishing slurry determined by electrochemical impedance spectroscopy and potentiodynamic polarization test. Consequently, this manufacturing process has the potential to simplify considerably the fabrication and integration of surface-modified diamond grits on pad dresser-compatible substrates.     

Profiled rotary dresser with controlled size and distribution of abrasive grits: Performance assessment

This paper reports on a novel proprietary profiled rotary dresser which, in contrast with conventional tools, enables a controlled arrangement of geometrically defined abrasives over complex profiles. Output forces and abrasives’ wear were investigated during dressing and grinding tests. This showed a significant reduction in radial dressing forces (˜37%) and volumetric loss of material per grit (˜21%) when compared with conventional tools, together with low grinding forces and workpiece surface roughness variability for different wear conditions. The novel dresser proves the ability to obtain uniform wear rates along complex profiles, while allowing abrasive segment replacement to restore the dressing conditions.     

Rotary dressing model for grinding wheel active surface prediction

A kinematic model of rotary dressing of corundum grinding wheels is presented. Based on wheel and dresser specifications and process kinematics, effects of rotary dressing parametres on wheel topography are predicted. For model validation, wheel surface is characterized by areal roughness parametres, obtaining a deviation less than 15%. Besides, influence of wheel topography on ground part surface quality is investigated. Results highlight the significance of modelling the dressing process and show the model translates into a useful tool for selection of most suitable dressing parametres for achieving specific surface qualities. Moreover, it eases the way to predicting dressing originated defects.     

cBN砂轮在低速磨削中的应用

cBN砂轮在高速设备上使用非常广泛,但在老式低速磨床上采用cBN砂轮的非常少。我们在这方面做了大胆的尝试,就是在老式磨床上不做任何改进,直接更换相同直径的陶瓷cBN砂轮,通过更换皮带轮改变传动比,把砂轮速度从51.4 m/s提升到64.8 m/s,增大冷却液流量、压力,确定冷却液冲刷位置,改变切削的进给量,使cBN砂轮的一个修整频次内寿命大幅提升。最后证明陶瓷cBN砂轮在低速磨床中一样可以替代刚玉砂轮,并且不需要大的改造投资,可以获得非常好的综合经济效益。     

精密磨削Invar36合金时的磨料选择

本文对白刚玉、铬刚玉和绿色碳化硅三种磨料砂轮磨削Invar36合金时的磨削力、磨削温度、表面粗糙度和磨削比进行了对比分析。结果表明：白刚玉砂轮对Invar36合金的磨削比最高,磨削表面粗糙度较好,但是磨削温度和磨削力也比较高,适用于Invar36合金的粗磨;铬刚玉砂轮磨削时的磨削力最小,磨削温度最低,但是磨削比也比较低,因此适用于易变形零件的精密磨削。