Tool path generation of ultra-precision diamond turning: A state-of-the-art review

With the increasing market demand for optical complex surface parts,the application of multi-axis ultraprecision single-point diamond turning is increasing.A tool path generation method is very important to decrease manufacturing time,enhance surface quality,and reduce cost.Compared with the tool path generation of the traditional multi-axis milling,that of the ultra-precision single-point diamond turning requires higher calculation accuracy and efficiency.This paper reviews the tool path generation of ultra-precision diamond turning,considering several key issues:cutter location(CL)points calculation,the topological form of tool path,interpolation mode,and G code optimization.

A novel method to improve interfacial bonding of compound squeeze cast Al/Al-Cu macrocomposite bimetals:Simulation and experimental studies

A facile and innovative method to improve bonding between the two parts of compound squeeze cast Al/Al-4.5 wt.%Cu macrocomposite bimetals was developed and its effects on microstructure and mechanical properties of the bimetal were investigated.A special concentric groove pattern was machined on the top surface of the insert(squeeze cast Al-4.5 wt.%Cu) and its effects on heat transfer,solidification and distribution of generated stresses along the interface region of the bimetal components were simulated using ProCAST and ANSYS softwares and experimentally verified. Simulation results indicated complete melting of the tips of the surface grooves and local generation of large stress gradient fields along the interface. These are believed to result in rupture of the insert interfacial aluminum oxide layer facilitating diffusion bonding of the bimetal components. Microstructural evaluations confirmed formation of an evident transition zone along the interface region of the bimetal. Average thickness of the transition zone and tensile strength of the bimetal were significantly increased to about 375 μm and 54 MPa, respectively, by applying the surface pattern.The proposed method is an affordable and promising approach for compound squeeze casting of Al-Al macrocomposite bimetals without resort to any prior cost and time intensive chemical or coating treatments of the solid insert.

微结构功能表面的金刚石超精密加工仿真与试验

为解决微结构功能表面的金刚石超精密加工过程中,难以经济而灵活地预测表面质量及加工条件对加工表面质量的影响的问题,以自行设计的带有快速伺服刀架的超精密机床为基础,采用Matlab/Simulink模块建立正弦波微结构功能表面金刚石超精密加工过程的动态仿真模型。利用该模型,不仅可以预测加工表面质量,还可以对加工条件如进给速度、主轴转速对加工表面质量的影响进行仿真进而对加工条件进行优化。通过微结构功能表面的金刚石超精密切削加工验证试验,加工出表面粗糙度约为45nm、形状精度约为0.65μm的正弦波微结构功能表面,试验结果表明,该模型的建立对于微结构功能表面的金刚石超精密加工具有重要的指导意义。

聚晶金刚石表面加工质量对比试验研究

为解决聚晶金刚石(PCD)表面加工成型和抛光难题,提高PCD加工效率和表面加工质量,采用电火花粗、精放电加工工艺及金刚石砂轮磨削加工工艺对PCD表面进行加工,并采用SEM、EDS、XRD和Raman等观察分析不同加工方式下PCD的表面形貌、表层组织及结构,对不同加工方式下PCD的显微硬度和耐磨性进行测试,考察不同加工方式对PCD表层微结构与力学性能的影响。结果表明:电火花加工后PCD表面会发生金刚石石墨化,而机械磨削加工后则不会;电火花精加工后PCD的显微硬度和耐磨性分别是5613HV10和Q5.8×10^4,机械磨削加工后则分别是5727HV10和Q5.4×10^4,二者相比变化不大,而电火花粗加工后的则是4604HV10和Q4.7×10^4,性能降低明显。同时提出放电加工后PCD表面变质层的概念,并讨论其变质层产生的原因。

钛合金切削表层微观组织研究进展

钛合金是航空发动机关键构件的主选材料,切削加工是其制造工艺中最基本的加工方法之一。切削加工产生的热-机载荷会导致钛合金表层微观组织发生复杂变化,从而在加工表面形成表面变质层。表层微观组织严重影响着工件的物理、力学性能,因此,研究钛合金切削表层微观组织对改善航空发动机关键构件的使役性能与可靠性有重要意义。基于表面变质层的形成机理,工艺因子对表层微观组织的影响规律以及微观组织的模拟与预测三个方面的研究成果,介绍钛合金切削表层微观组织的研究现状。最后,分析现有研究存在的一些不足以及未来的研究方向。