砂轮约束磨粒喷射精密光整加工表面功率谱分析和摩擦磨损特性研究

对砂轮约束磨粒喷射精密光整加工微观形貌进行功率谱分析和摩擦磨损特性研究。利用平面磨床M7120对精磨后45#钢工件材料进行喷射精密光整加工;用TALYSURF5轮廓仪测量加工后的微观几何参数值;用扫描电镜观察表面微观形貌变化;用功率谱密度函数评价磨削加工和光整加工表面的微观形貌特征;利用MG-2000型销-盘式高速高温摩擦磨损试验机研究表面形貌对摩擦磨损的影响。结果表明,磨粒喷射精密光整加工均化和改善了工件表面的波纹度,降低了工件表面粗糙度值,提高了工件表面的形状精度;光整加工表面摩擦因数和磨损量与磨削加工表面相比明显降低,表面质量明显改善,从而提高了零件的使用寿命和精度保持性,摩擦磨损实验结果和功率谱密度分析相吻合。     

砂轮约束磨粒喷射精密光整加工表面微观形貌的研究

对砂轮约束磨粒喷射精密光整加工表面微观形貌进行分析，研究了工件表面尖峰去除机理和均化及改善波纹度机理。利用平面磨床M7120对精磨后的Q235A工件材料进行喷射加工实验，采用TALSURF5轮廓仪测量加工后表面的微观几何参数值，用扫描电镜观察表面微观形貌变化，用金相显微镜观察磨削烧伤。实验结果表明，随着加工循环次数的增加，表面微观形貌由方向一致的沟槽过渡到随机的、无方向性的微细凹坑，表面粗糙度值明显降低，喷射加工能减轻或消除磨削烧伤。     

砂轮约束磨粒喷射精密光整加工表面特性的实验研究

主要对砂轮约束磨粒喷射精密光整加工表面特性进行研究.利用平面磨床M7120和磨粒喷射装置对45钢进行喷射光整加工实验,用TALYSURF5轮廓仪测量加工后的微观几何参数值,用扫描电镜和金相显微镜观察表面微观形貌和断面金相组织变化,用HVS-1000型数字显微硬度计测量表面硬度,用X射线能谱仪对工件表面进行物相分析,用PW3208 X射线衍射仪Cr靶辐射测试残余应力.实验结果表明,该加工方法在减小表面粗糙度值和均化波纹度的同时,不仅提高表面硬度,而且在光整加工表面产生残余压应力,从而提高了零件的使用寿命和精度保持性.     

砂轮约束磨粒喷射加工外圆表面创成机理及三维形貌

磨粒喷射精密光整加工是重要零件在磨削后进行去除表面缺陷层、降低粗糙度和波纹度为目的光整加工新工艺。试验在MB1332A外圆磨床上完成,加工试样为表面粗糙度0.6 m左右的45钢。加工表面形貌和微观几何参数分别用扫描电子显微镜和Micromesvre2表面轮廓仪测量。应用自相关函数对磨削加工表面和光整加工表面进行分析,并研究材料去除机理和微观表面形貌的创成机理。在楔形区游离磨粒获得能量对工件进行抛磨、滑擦、和微切削是材料去除机理的核心因素,磨料流体侧向挤出是均化和降低表面波纹度的主要因素。试验结果表明,试样表面从连续的方向一致的沟槽被随机不连续的微坑所代替,表面粗糙度明显得到改善。随着加工循环的增加,工件表面的粗糙度值由0.6 m下降到0.2 m左右。此外,光整加工可以获得各向同性网纹交错的表面,表面轮廓的支撑长度率提高,对工件的耐磨性有利。     

砂轮约束磨粒喷射精密光整加工材料去除机理研究

基于磨粒特征尺寸与砂轮、工件间液膜厚度比值的变化,研究了砂轮约束磨粒喷射精密光整加工材料去除机理。分析了在两体加工及三体加工模式条件下,单颗磨粒运动特点以及磨粒由两体研磨加工向三体抛光加工转变的临界条件。实验证明,砂轮约束磨粒喷射光整加工中,随着加工循环的增加,工件表面微观形貌变化规律与理论分析相同,实验结果和理论分析吻合很好。     

砂轮约束磨粒喷射加工表面材料去除机理

基于磨粒特征尺寸与砂轮、工件间液膜厚度比值的变化研究了磨粒喷射光整加工的材料去除机理,建立了两体研磨及三体冲蚀单颗磨粒的材料去除模型和材料去除率模型。试验在MB1332A外圆磨床上完成,加工试样为Sa=06μm左右的45钢。加工表面形貌和微观几何参数分别用SEM和MICROMESVRE2表面轮廓仪测量,试验结果和材料去除模型相吻合。试样表面连续的方向一致的沟槽被随机不连续的微坑所代替,随着加工循环的增加,Sa值由06μm下降到02μm左右。此外,光整加工可以获得各向同性网纹交错的表面,表面轮廓的支撑长度率提高,对工件的耐磨性有利。      

夹心式复合加工表面形貌特征

对夹心式电化学机械复合光整加工设备进行了改进，通过工艺试验广泛地搜集了大量试验数据，确定了较合理的工艺参数。依据试验数据，多角度地研究了电化学机械复合光整加工的表面形貌特点，并从理论上深入讨论了电化学机械复合光整加工表面形貌对工件工作性能的影响，最后得出的结论为：电化学机械复合光整加工对工件原始表面的低频成分有较大程度的降低，而对高频成分影响较小，有明显的阳极整平作用，被加工工件表面的尖峰状凸起被去除，工件表面呈现出微观“高原型”，表面轮廓不平度高度特性参数大幅度降低，工件表面轮廓分布集中，且呈负偏态，轮廓偏斜度为负值，轮廓支承长度率曲线陡峭，工件的表面质量得到综合改善，这对提高零件的抗接触变形能力、改善摩擦、磨损性能、降低工件的磨合时间、提高工件的精度保持性、延长工件的寿命均有利。     

磁性磨粒光整加工钛合金板的实验研究

利用磁性磨粒光整加工的方法研磨抛光钛合金板,并测量了抛光后的工件表面粗糙度。由于钛合金是非导磁性工件,可以通过增加永磁铁来改善加工区域的磁场特性,并用仿真软件模拟了增加永久磁铁和不加永久磁铁时加工钛合金的磁感应强度的大小。最后,采用正交试验方法来评估在磁性磨粒光整加工过程中旋转速度、加工间隙、磨粒类型及加工时间对工件表面粗糙度的影响。为了获得较好的加工表面,用方差分析和SN比寻求较好的试验条件。结果表明,磁性磨粒光整加工能够有效的抛光钛合金表面,获得理想的表面粗糙度。     

摩擦副表面微观动压效应集成、传递及影响的研究

为探讨摩擦副表面微观几何形貌的影响,基于试验数据的分析,利用分形几何理论和FLUENT等软件,分析和仿真模拟了磨削加工与电化学光整加工的表面微观几何形貌对动压效应的影响。结果表明：与磨削加工相比,电化学光整加工借助对表面微观几何形貌的改形,提高其规则化程度来改变微观动压效应的强弱分布;微观动压效应集成的结果形成膜压分布不均的压力场,而传递使压力场具有波动特性,形成压力波;与磨削加工相比,电化学光整加工的表面具有强化动压效应、改善压力场的波动及其稳定性的能力,可实现减阻、降磨及减振,有利于提高摩擦副的使用性能。     

磨削液对陶瓷结合剂CBN砂轮磨削性能影响

分析了磨削液对陶瓷结合剂CBN砂轮磨削性能的影响，使用3种磨削液在精密外圆磨床M1420E上进行了磨削加工实验，用加工表面微观形貌、表面粗糙度R。值、工件表面残余应力以及砂轮径向磨损量对磨削液效能进行评价。结果表明，轻质润滑油不仅能提高工件表面质量，降低表面粗糙度值，而且砂轮磨损量明显降低，乳化液和化学合成液对磨削性能的影响各有利弊，润滑油是陶瓷结合剂CBN砂轮磨削的优选磨削液。     

颗粒增强复合材料加工表面粗糙度及刀具设计

分析了颗粒增强金属基复合材料的加工表面形貌特点。通过切削试验 ,研究了切削用量和材料组织结构对SiCp/Al已加工表面粗糙度的影响 ,并根据切削表面成形机理及刀具磨损的特征 ,设计了具有引导光整作用的硬质合金刀具。试验结果表明 ,该刀具可显著降低加工表面粗糙度和提高刀具寿命     

电化学机械光整加工表面形貌研究

提出了用于圆柱表面精密光整的夹心式电化学机械加工装置核心部件设计方案,探讨了主要工艺参数对表面质量影响规律。对采用这种新型加工方法所产生表面的轮廓高度特性、间距特性、形状特性、轮廓峰分布及表面波纹度进行了试验研究,结果表明电化学机械光整表面轮廓以高频小振幅波度为主要成分。     

Influence of electrical discharge machining on the reciprocating sliding wear response of WC-Co cemented carbides

A number of commercially available WC-Co-based cemented carbides with 6 up to 12 wt.% Co were machined and surface finished by grinding as well as by wire electrical discharge machining (EDM) in demineralised water through a number of consecutive gradually finer EDM regimes. Comparative dry reciprocating sliding wear experiments on both wire-EDM and ground samples against WC-Co pins were conducted, using a pin-on-plate test rig, in order to investigate the influence of the EDM process on the tribological behavior. The worn surfaces of the investigated cemented carbides were scanned topographically and characterised by scanning electron microscopy (SEM). The post-mortem obtained wear volumes were compared to the online measured wear in order to determine correlations between wear volume and wear rate on the one hand and sliding distance on the other hand. The experimental results revealed a profound influence of surface finish conditions and distinctive EDM regimes on the wear behavior of WC-Co cemented carbides.     

Softness abrasive flow method oriented to tiny scale mold structural surface

Tiny scale mold structural surface finishing is of high difficulty. In allusion to the problem, a new no-tool precision finishing method based on solid–liquid two-phase softness abrasive flow (SAF) is brought forward. By setting restrained component for the structural surface machined, the restrained flow passage is constructed. Using the wall effect of SAF, no-tool precision finishing for tiny scale structural surface can be realized. According to the Nikuradse’s experimental principles, the motion regulars of SAF are studied, and the friction coefficient formulas suited for SAF finishing are obtained. Taking U-shaped restrained flow passage as instance, standard k-ε model and Euler multiple-phase model are used to describe the SAF flow field, and the kinetic model of SAF is established based on discrete phase model. Then, the variation trends of SAF turbulent parameters and flow passage pressure distribution with different inlet velocities are acquired by semi-implicit method for pressure-linked equations consistent algorithm. Numerical simulation results derived that pressure attenuation of solid phase in flow passage is inversely proportional to inlet velocity, and the motion trails are disordered and stochastic, which are the sufficient conditions of SAF finishing. By analyzing pressure distribution and turbulent characteristics of SAF, the best finishing area in restrained flow passage is gained. Observational experiment of particles motion had been carried out; experimental results showed particles’ motion satisfied requirements of SAF finishing, and feasibility of SAF could be proved theoretically. SAF experimental platform oriented to module structural surface finishing is constructed, and the nano-level finishing can be realized. Experiment results show that SAF method can increase mold structural surface precision more than ten times, and the roughness machined in Ra value is less than 62?nm.     

Producing gear teeth with high form accuracy and fine surface finish using water-lubricated chemical reactions

A new method was investigated for high-accuracy fine finishing of gear teeth surfaces using a water-lubricated tribo-chemical technique. A pair of shaved gears with rather low surface roughness was rotated in water lubricant for 30 min so that the gear tooth surface contacting the mating tooth was ‘worn’ to a mirror surface and ideal tooth profile, due to the mechano-chemical mild erosion of the contact area. The wear rate was 2.0 μm per 20,000 meshings, corresponding to a wear of one atomic radius thickness per meshing. Oxidation of the steel surface by water molecules is proposed as the dominant wear process. Operation noise from the gear pair rotation was drastically reduced to lower than about 10–15 dB compared to conventionally machined gear surfaces (30 dB in average), as a result of the wear of the tooth surface to form a best-fit profile. The noise increased with further processing of the gear pair. Thus, there is an appropriate number of rotations for suitable surface wear treatment. This new and simple procedure for surface treatment assures saving in energy, and does not require expensive honing techniques or high-accuracy grinding tools.The wear mechanisms used in this process are discussed along with the application of the technique to other processes for precision finishing.     

Ultra-precision grinding of optical glasses using mono-layer nickel electroplated coarse-grained diamond wheels. Part 2: Investigation of profile and surface grinding

After finishing the precision conditioning of mono-layer nickel electroplated coarse-grained diamond wheels with 151 μm (D151), 91 μm (D91) and 46 μm (D46) grain size, resp., profile and surface grinding experiments were carried out on a five-axis ultra-precision grinding machine with BK7, SF6 optical glasses and Zerodur glass ceramic. A piezoelectric dynamometer was used to measure the grinding forces, while an atomic force microscopy (AFM), white-light interferometer (WLI)) and scanning electron microscope (SEM) were used to characterize the ground surface quality in terms of micro-topography and subsurface damage. Moreover, the wear mechanics of the coarse-grained diamond wheels were analyzed and the grinding ratio was determined as well, in aiming to evaluate the grinding performance with the conditioned coarse-grained diamond wheels. Finally, the grinding results were compared with that of the fine-grained diamond wheels with regard to the ground specimen surface quality, process forces and wheel wear as a function of stock removal. The experimental results show that the precision conditioned coarse-grained diamond wheels can be applied in ductile mode grinding of optical glasses with high material removal rates, low wheel wear rates and no dressing requirement yielding excellent surface finishes with surface roughness in the nanometer range and subsurface damage in the micrometer range, demonstrating the feasibility and applicability of the newly developed diamond grinding technique for optical glasses.