Curvature in Surface Grinding of Thin Workpieces with Superabrasive Wheels

The warp of steel and brittle material thin workpieces in one-pass surface grinding has been studied, using WA, CBN, and diamond wheels. The grinding experiments were conducted on annealed and hardened steels, sintered alumina, cemented carbide and silicon, whose size was 1.5mm thickness and 100mm length, at depths of cut to 30μm. Grinding force, as well as residual stress, was measured to interpret the results of curvature. A SEM micrographic study of grinding affected zone was performed. Thus, the difference in curvature for the WA, CBN, and diamond wheels was evident. The superabrasive wheels, especially diamond wheel, tend to cause a convex curvature, and a major reason for the inclination to convex curvature is considered a plastically deformed layer.     

结构化超硬磨料砂轮设计与制备研究进展

从减摩降力、导屑促排、储液换热的角度出发,探索结构化砂轮在降低磨削力及磨削温度、抑制工件表面热损伤、提高工件加工表面完整性等方面的有效方法。以砂轮表面/基体结构的几何形状、三维尺寸及排布方式等因素对磨削性能的影响为主线,对结构化砂轮设计、制备的基本原理与最新进展进行了全面的论述和总结,重点揭示了结构表征参数-砂轮磨削性能-工件表面质量的内在关联,深入剖析了结构化砂轮在磨削中的优越性,并预测了其未来发展趋势,旨在为推进超硬磨料结构化砂轮的设计及制备技术发展提供理论指导和实践经验。     

Profiled Superabrasive Grinding Wheels for the Machining of a Nickel Based Superalloy

Machining data are presented for small diameter, profiled (fir tree root form), single layer/electroplated CBN (B46, B76 and 91) and diamond (D46) grinding wheels, when cutting Udimet 720. Spindles operating at 60,000 and 90,000 rpm were employed, with a synthetic polyalphaolefine (PAO) oil based fluid in a down grinding mode on single sided specimens. Operating parameters were selected to reflect finishing conditions. Measured tool wear was lower for CBN grit as compared to diamond however workpiece roughness was lower with Ra approaching 0.75 μm when using D46 wheels. Higher rotational speed produced lower grinding wheel wear. No workpiece burning was observed irrespective of grit type at the conditions tested.     

超硬磨料砂轮修整与激光修整新进展

本文介绍了超硬磨料砂轮修整的现状和特点，指出超硬磨料砂轮修整的关键和亟待解决的问题。重点介绍一种很有前途的修整技术－－激光修整，分析了其国内外近年来的研究情况。作者用声光调QYAG激光对树脂结合剂CBN砂轮进行了修锐试验，得出了声光调QYAG激光适宜修锐树脂结合剂砂轮的结论。对今后的超硬磨料砂轮激光修整的发展方向作了展望；建立材料热去除模型和气体动力学模型，完善激光修整机理的研究；实现激光整形和修锐过程同时进行；深入研究激光精密修整技术；开发成形砂轮激光修整技术；开发自适应控制修整系统，实现激光在线修数；提高修整效率。     

采用CBN砂轮磨削气缸体Ni-SiC复合镀层

与离子溅射、火焰溅射、CVD等方法相比较, 采用电沉积方法形成的复合镀层有着非常优越的性能,但同时复合镀层的精密加工亦成为制约其性能发挥的关键.某小型航空发动机气缸体中由于有Ni-SiC复合镀层,其内孔磨削的难加工是制约该型号发动机性能的关键工艺.针对该缸体的特殊结构及镀层特点,文中采用合理的装夹方式及磨削工艺参数,在精密内圆磨床上采用陶瓷结合剂CBN砂轮实现了对Ni-SiC复合镀层内孔的磨削.实践证明,该工艺方法解决了Ni-SiC弥散复合镀层的精密加工难题,提高了加工效率,改善了表面尺寸形状精度和表面粗糙度.     

仿鸟羽结构自润滑金刚石砂轮磨削碳化硅陶瓷实验研究

目的 减少金刚石砂轮磨削工程陶瓷材料时的砂轮磨损,改善加工表面质量。方法 以人造金刚石为磨料,青铜结合剂为黏结剂,加入一定质量分数的二硫化钼和二氧化钛纳米颗粒作为填充材料,制备出青铜结合剂自润滑金刚石砂轮。利用脉冲激光在金刚石砂轮表面烧蚀出经设计的仿鸟羽减阻几何结构,得到新型仿鸟羽结构自润滑金刚石砂轮。制备了4种不同工况砂轮,传统青铜金刚石砂轮（TGW）、纳米自润滑金刚石砂轮（NGW）、仿鸟羽结构化金刚石砂轮（FGW）、仿鸟羽结构化纳米自润滑金刚石砂轮（FNGW）以对比其磨削性能差异。开展Si C陶瓷磨削实验,研究FNGW磨削机理。从磨削力、表面质量、砂轮磨损3个方面评价FNGW磨削性能。结果 纳米颗粒的加入不会降低砂轮力学性能,砂轮表面的仿鸟羽结构激光成型烧蚀质量较高,对未烧蚀区域没有影响。与TGW相比,FGW除工件表面粗糙度值Ra与砂轮磨损有略微改善外,其他磨削性能都有明显提升。NGW磨削性能都有所提升,但提升效果不太明显。结合二者优势的FNGW,其各磨削性能都有显著提升。其中磨削力最大降低了65.1%,工件表面粗糙度值Ra最大降低了21.5%,砂轮磨损明显减少,有效提升了砂轮的使...     

陶瓷结合剂CBN砂轮磨损与磨削比的研究

通过对国产陶瓷结合剂CBN砂轮磨削45淬硬钢的试验,研究了磨削参数对CBN砂轮磨损与磨削比的影响规律,获得了磨削参数的最优水平,并建立磨损与磨削比的经验公式,探讨了冷却液流量对磨损与磨削比的影响规律。     

An Investigation of Grinding with Electroplated CBN Wheels

Grinding of hardened bearing steel with electroplated CBN wheels was Investigated with particular attention to how the wear of the abrasive grains affects the wheel topography and grinding performance during the wheel ire. Power, surface roughness, and wheel topography data were obtained throughout the wheel life for internal cylindrical grinding. Dulling of CBN gratis by attrition was found to cause an increase in the grinding power, but the degree of dulling was restricted mainly by grain fracture and also by grain pullout. Grain fracture and pullout had a much smaller effect on the progressive increase in active grain density, which caused the surface roughness to progressively decrease. Wheel failure tended to occur by stripping of the abrasive layer when the radial wear reached about 70% - 60% of the grain dimension     

Factors Affecting Grinding Performance with Electroplated CBN Wheels

An experimental investigation was conducted to evaluate the effect of CBN crystal characteristics and plating thickness on the performance of electroplated CBN wheels. Wheels containing tougher CBN crystals generally exhibited less wear and a higher G-ratio, and also required less power. Furthermore, contrary to expectations, less wear and higher G-ratio were also obtained for wheels with a thinner layer of nickel plating despite an increased tendency for large-scale crystal loss. This would indicate that the overall wheel wear depends more on crystal exposure than on active grain density, which could facilitate chip removal and grinding fluid access. Extended grinding tests up to wheel failure ascertain the improved grinding performance with tougher crystals and thinner electroplated layers.     

瓷质玻化砖磨抛加工磨具及加工工艺研究

研究了用于手扶磨机磨抛瓷质玻化砖的磨具。通过磨抛试验,分析了粗磨和抛光前加工质量、精磨和抛光磨具等对抛光质量、磨削效率和磨具磨损的影响。     

自锐性金刚石树脂砂轮磨削性能的研究

本文通过对比磨削试验，研究了自锐性金刚石(CSD)树脂砂轮的磨削性能。试验结果表明，由于CSD形状小规则，有许多凹入角和粗糙表面，树脂结合剂对CSD的把持力较普通金刚石强，所以在磨削各参数相同的条件下，自锐性金刚石砂轮与普通金刚石砂轮相比，其磨削比提高60％以上。且由于CSD的内部为许多单个亚晶粒所组成的镶嵌的颗粒，因此在应力作用下，只有很小的不规则的碎片崩掉，从而在每个颗粒的表面上留下许多新的小切削刃，故其加工工件的表面粗糙度值较低。     

Power and Wheel Wear for Grinding Nickel Alloy with Plated CBN Wheels

Electroplated CBN grinding wheels are manufactured with a single layer of abrasive grains. The grinding performance of these plated wheels changes significantly as the wheel wears down. The present investigation was undertaken to understand the transient grinding behavior with electroplated CBN wheels in order to provide a logical basis for process control. In this paper, particular attention is directed to the effect of wheel wear and operating parameters on grinding of a nickel alloy. Wheels were worn to various stages and then used to perform grinding tests under various grinding conditions to measure grinding forces and power and to produce ground specimens. Based on models for grinding with conventional aluminum oxide wheels, a power model for grinding of a nickel alloy with plated CBN wheels was established and validated. Microscopic observations of the ground specimens reveal that thermal damage in the form of a White Etch Layer (WEL) appears only when grinding with a worn wheel under conditions that lead to high temperatures.     

Speed-Stroke Grinding of Advanced Ceramics

The effectiveness of speed-stroke grinding, featured by a high workpiece speed and a small depth of cut, is experimentally investigated. It has been confirmed that the method is quite efficient in decreasing the grinding force. The surface roughness is, however, increased and the depth of crack is considered to be increased as well. Those characteristics are the result of the material removal process which depends on the micro-brittle fracture of the advanced ceramics. To remove the damaged surface layer, finish grinding is needed. Optimum combination of roughing and finishing is a keypoint for increasing the efficiency.     

表面硬化钢磨削烧伤的监测和预报

成型磨削齿轮之类的表面硬化钢零件时极容易发生磨削烧伤的现象,严重地破坏了零件的表面完整性,降低了零件的使用性能。对表面硬化钢进行了大量宽磨削宽度的切入式磨削试验证实,用相对容易测量的磨削力和磨削参数计算所得的单位面积磨削功率P_c″与砂轮——工件接触区最高平均温度T_(max)间有极好的函数对应关系,表面质量的各种不同的检测结果完全与P_c″相对应,P_c″的二个临界值P_(cⅠ)″和P_(cⅡ)″以及F_n/F_t的变化率可用来预报和判别磨削烧伤的发生,并估算磨削表面残余应力值,从而为生产过程提供了切实可行的磨削烧伤监测和预报方案。