C/E 复合材料“以磨代钻冶制孔工艺

为了提高C/E复合材料构件制孔加工质量,以C/E复合材料为研究对象,提出"以磨代钻"制孔新工艺,并研制了电镀金刚石刀具.与传统硬质合金刀具钻孔工艺进行对比试验,结果表明:金刚石刀具钻削轴向力降低30%-50%、刀具耐用度提高3-5倍、缺陷显著减少,更适合C/E复合材料钻孔加工.     

叶片型面砂带磨削技术的现状和发展趋势

叙述了国内外叶片型面砂带磨削的各种技术,分析了一些叶片材料的砂带磨削性能,并介绍了一些典型的叶片砂带磨床.     

GH4169磨削表面粗糙度影响参数的敏感性研究

通过GH4169高温合金平面切入磨削实验,建立了表面粗糙度的经验公式,分析了表面粗糙度对磨削参数的灵敏度,获得了磨削参数稳定域和非稳定域。结合正交试验法中的极差分析方法获得了不同磨削参数对表面粗糙度的影响曲线,进行了磨削参数区间的优选。研究结果表明:表面粗糙度对磨削深度的变化最为敏感,对工件速度的变化敏感次之,对砂轮速度的变化最不敏感;磨削深度优选范围为0.01～0.015mm,工件速度优选范围为10～15m/min,砂轮速度优选范围为20～30m/s,可控制表面粗糙度在0.7μm以内。为高温合金材料磨削表面粗糙度控制提供理论方法和试验依据。     

Investigation on induction brazing of profiled cBN wheel for grinding of Ti-6Al-4V

Profiled monolayer cBN wheel was induction brazed for grinding of titanium dovetail slot in this study. Aimed at acquiring a uniform temperature distribution along the profiled surface and reducing the thermal deformation of the brazed wheel, a finite element model was established to investigate the temperature uniformity during induction brazing. A suitable induction coil and the related working parameters were designed and chosen based on the simulation results. Ag-Cu-Ti alloy and cBN grains were applied in the induction brazing experiment. The results showed geometric deformation of the brazed wheel was no more than 0.01 mm and chemical reaction layer were found on the brazed joint interface. Further validation tests were carried out by grinding of Ti-6Al-4V alloy. Compared to the electroplated wheel, the brazed wheel showed better performance such as low specific grinding energy and good ground quality in grinding of Ti-6Al-4V alloy. Abrasion wear was found to be the main failure mode for the induction brazed wheel, while adhesion and grains pull-out were the main failure mode for the electroplated wheel.     

Effect of creep feed grinding on surface integrity and fatigue life of Ni3Al based superalloy IC10

Ni₃Al-based superalloy IC10 is widely used in high temperature components of aero-engines because of its superior mechanical properties. In this paper, the creep feed grinding properties of IC10 were investigated experimentally. The effects of grinding parameters on the grinding forces and temperature were examined. Moreover, the influences of surface roughness and hardening on the high-cycle fatigue life of IC10 specimens were studied. To control the creep feed grinding parameters and enhance the fatigue life of IC10 components, the experimental results were summarized to offer a useful reference point. It is concluded that, the grinding depth is the most important factor which influencing the grinding forces and temperature; the surface roughness is the main and unfavorable factor on the fatigue life of IC10, while the surface hardening has a positive influence on the fatigue life; to obtain a better surface quality and improve the fatigue life of IC 10, the recommended grinding parameter domain involves wheel speed ∈ [15, 20] m/s, feed rate ∈ [150, 200] mm/min, and grinding depth ∈ [0.4, 0.5] mm.     

Interference and grinding characteristics in ultra-precision grinding of thin-walled complex structural component using a ball-end grinding wheel

As for ultra-precision grinding of difficult-to-process thin-walled complex components with ball-end grinding wheels, interference is easy to occur. According to screw theory and grinding kinematics, a mathematical model is established to investigate the interference and grinding characteristics of the ball-end wheel. The relationship between grinding wheel inclination angle, C axis rotation angle, grinding position angle and grinding wheel wear are analyzed. As the grinding wheel inclination angle increases, the C axis rotatable range decreases and the grinding position angle increases. The grinding position angle and wheel radius wear show a negative correlation with the C axis rotation angle. Therefore, a trajectory planning criteria for increasing grinding speed as much as possible under the premise of avoiding interference is proposed to design the grinding trajectory. Then grinding point distribution on the ball-end wheel is calculated, and the grinding characteristics, grinding speed and maximum undeformed chip thickness, are investigated. Finally, a complex structural component can be ground without interference, and surface roughness and profile accuracy are improved to 40.2 nm and 0.399 μm, compared with 556 nm and 3.427 μm before ultra-precision grinding. The mathematical model can provide theoretical guidance for the analysis of interference and grinding characteristics in complex components grinding to improve its grinding quality.     

Minimum quantity lubrication machining of aeronautical materials using carbon group nanolubricant: From mechanisms to application

It is an inevitable trend of sustainable manufacturing to replace flood and dry machining with minimum quantity lubrication (MQL) technology. Nevertheless, for aeronautical difficult-to-machine materials, MQL couldn’t meet the high demand of cooling and lubrication due to high heat generation during machining. Nano-biolubricants, especially non-toxic carbon group nano-enhancers (CGNs) are used, can solve this technical bottleneck. However, the machining mechanisms under lubrication of CGNs are unclear at complex interface between tool and workpiece, which characterized by high temperature, pressure, and speed, limited its application in factories and necessitates in-depth understanding. To fill this gap, this study concentrates on the comprehensive quantitative assessment of tribological characteristics based on force, tool wear, chip, and surface integrity in titanium alloy and nickel alloy machining and attempts to answer mechanisms systematically. First, to establish evaluation standard, the cutting mechanisms and performance improvement behavior covering antifriction, antiwear, tool failure, material removal, and surface formation of MQL were revealed. Second, the unique film formation and lubrication behaviors of CGNs in MQL turning, milling, and grinding are concluded. The influence law of molecular structure and micromorphology of CGNs was also answered and optimized options were recommended by considering diverse boundary conditions. Finally, in view of CGNs limitations in MQL, the future development direction is proposed, which needs to be improved in thermal stability of lubricant, activity of CGNs, controllable atomization and transportation methods, and intelligent formation of processing technology solutions.     

纤维增强复合材料钻削分层的研磨检测

复合材料钻削分层缺陷是影响复合材料构件后续加工质量和效率的关键因素之一,针对该问题,设计不同钻深孔的分层缺陷产生与检测实验,揭示分层产生及演变历程。获得了孔出口三维分层形貌,分析了分层缺陷动态变化及影响。     

Al2O3陶瓷蠕动进给超声磨削特性试验研究

在改装成的超声磨削机床上进行了陶瓷超声磨削与普通磨削的对比试验,以揭示蠕动进给超声磨削加工的磨削特性及其材料去除机理。结果表明:当超声振动方向与磨削进给方向相同时,超声振动所引起的抛磨作用非常显著,超声磨削的表面粗糙度比机械磨削的低;Al2O3陶瓷在一般条件下超声磨削的去除方式仍属于脆性断裂,以晶粒粉碎、穿晶断裂为主,但伴随有沿晶断裂、弹性划擦、塑性流动等现象。     

垂直磨削中磨削参数对磨削痕迹分布的影响

针对垂直磨削中磨削痕迹分布规律不明晰而使得磨削表面质量难以准确控制的问题,开展垂直磨削中磨削参数对磨削痕迹分布规律影响的研究。依据单颗磨粒磨削痕迹分布方程、仿真分析和探讨了砂轮转速、工件转速、进给速度、转速比和相移对磨削痕迹分布的影响,基于磨削参数对磨削痕迹分布和残留高度的影响,优选出了磨削痕迹分布相对合理的磨削参数组合,并进行磨削加工对比实验。结果表明,垂直磨削法中,磨削参数通过改变磨削痕迹的长度、间距、数量、位置关系和分布情况等影响磨削后工件的表面质量。其中,相移的大小会影响磨削痕迹的首尾相接与相互错开情况,直接决定着磨削纹理的形成与否,进而成为影响磨削后工件表面质量的关键因素;此外,尽管磨削参数中工件转速相差很小,但磨削痕迹分布状况会出现显著的差异,进而导致工件表面纹理和破碎情况显著不同及表面粗糙度Ra存在59~125 nm的差距。因此,基于磨削参数对磨削痕迹分布的影响,合理的匹配磨削加工参数可大幅提高工件表面质量。