Finishing effects of spiral polishing method on micro lapping surface

This study presents a spiral polishing method and a device for micro-finishing purposes. This novel finishing process has wider application than traditional processes. This offers both automation and flexibility in final machining operations for deburring, polishing, and removing recast layers, thereby producing compressive residual stresses even in difficult to reach areas. Applying of this method can obtain a fine polished surface by removing tiny fragments via a micro lapping generated by transmission of an abrasive medium through a screw rod. The effect of the removal of the tiny fragments can be achieved due to the function of micro lapping. The method is not dependent on the size of the work-piece's application area in order to carry out the ultra precise process. The application of this research can be extended to various products of precision ball-bearing lead screw. The proposed method produces products with greater precision and more efficiently than traditional processes, in terms of processing precisions and the surface quality of products. These parameters used in achieving maximum material removal rate (MRR) and the lowest surface roughness (SR) are abrasive particle size, abrasive concentration, gap, revolution speed and machining time.     

小口径火炮身管振动铰削的实验研究

论文研究了振动铰削降低表面粗糙度的机理，在此基础上通过硬质合金铰刀振动铰削小口径火炮身管的实验，深入分析了振动铰削对火炮身管内膛表面粗糙度的影响。振动铰削把普通铰削的连续切削过程转变为断续的脉冲式切削过程，将普通铰削时的螺旋状连续切屑变成了非常细小的针状单元切屑．增强了铰削加工的断屑排屑能力，从根本上抑制了积屑瘤的形成，避免了已加工表面的犁沟和鳞刺。实验表明，振动铰削的表面粗糙度Ra比普通铰削至少提高三级，振动铰削的表面粗糙度彤值不到晋通铰削Ry值的1／14，振动铰削使孔的已加工表面均匀一致，显著提高了身管内膛的表面质量。     

Effect of substrate surface roughness on the adherence of NiCrAlY thermal spray coatings

The adherence of plasma sprayed NiCrAlY bond coats can be improved by an appropriate substrate surface finish. The interface fracture energy for crack propagation along the coating/substrate interface has been measured for different surface roughness by means of a specially designed four-point bending test. An increase of the interface fracture energy of about 15% was observed for a three times higher surface roughness. In addition, four-point bending tests with the coating on the side face of bending specimens were performed to analyze the fracture and spalling behavior of the coatings both under large tensile and compressive substrate deformations.     

Fuzzy adaptive networks in machining process modeling: surface roughness prediction for turning operations

Due to the complexity of the machine tool structure and the cutting process, the dynamics of machining processes are still not completely understood. This is especially true due to the demand of high-speed machining to increase productivity. In order to model and control these complex processes, new approaches, which can represent complex phenomenon combined with learning ability, are needed. The combined neural–fuzzy approach appears to be ideally suited for this purpose. In this paper, the recently developed fuzzy adaptive network (FAN) is used to model surface roughness in turning operations. The FAN network has both the learning ability of neural network and linguistic representation of complex, not well-understood, vague phenomenon. Furthermore, it can continuously improve the initially obtained rough model based on the daily operating data. To illustrate this approach, a model representing the influences of machining parameters on surface roughness is established and then the model is verified by the use of the results of pilot experiments. Finally, a comparison with the results based on statistical regression is provided.     

Preparation of flee-standing diamond films for high frequency SAW devices

Free-standing diamond films were prepared by hot filament chemical vapor deposition （HFCVD） method under different conditions. Inter-digital transducers （IDTs） were formed on the nucleation sides of free-standing diamond films by photolithography technique. Then piezoelectric ZnO films were deposited by radio-frequency（RF） reactive magnetron sputtering to obtain the ZnO/diamond film structures. Surface morphologies of the nucleation sides and the IDTs were characterized by means of scanning electron microscopy （SEM）, atomic force microscope （AFM） and optical microscopy. The results indicate that the surfaces of nucleation sides are very smooth and the IDTs are of high quality without discontinuity and short circuit phenomenon. Raman spectra show the sharp diamond feature peak at about 1 334 cmI and the small amount of non-diamond carbon in the nucleation side. X-ray diffraction （XRD） patterns of the structure of ZnO/diamond films show a strong diffraction peak of ZnO （002）, which indicates that as-sputtered ZnO films are highly c-axis oriented.     

Technical note: Plasma-sprayed ceramic thermal barrier coatings for smooth intermetallic alloys

A durable ceramic thermal barrier coating is applied directly to a smooth, highly oxidation resistant intermetallic alloy in two layers. The first layer of ceramic is applied by low pressure plasma spraying and the second layer is applied by conventional atmospheric pressure plasma spraying. This approach would allow the use of plasma sprayed ceramic coatings in applications where a metallic bond coat is not desirable.     

二次喷丸42CrMo钢表面完整性的数值模拟研究

目的探究二次喷丸工艺参数对42CrMo钢零件表面完整性的影响规律。方法建立三维随机喷丸有限元模型,并通过实验验证有限元模型预测残余应力的准确性。将一次喷丸后零件的表面形貌和应力应变结果作为初始状态导入到二次喷丸模型中,构建出二次喷丸预测模型。分析二次喷丸参数对42CrMo钢零件表面残余应力场、表面粗糙度以及等效塑性形变场的影响情况。结果二次喷丸后,42CrMo钢零件近表层(0～100μm)的残余压应力值均比初始状态有所增加。增加二次喷丸覆盖率对表面残余应力的提升作用最为明显,最大可比初始状态提高63.3%,而增加二次喷丸直径对残余应力的改善效果最不明显。过度增加二次喷丸速度会导致表面粗糙度明显增加,提高二次喷丸覆盖率可显著降低表面粗糙度,覆盖率为300%时,粗糙度比初始状态减小了14.4%。表层PEEQ值随着二次喷丸速度、弹丸直径和覆盖率的增加而增加,但当二次喷丸速度、弹丸直径和覆盖率增加到一定程度后,表层PEEQ值会趋于饱和。结论二次喷丸预测模型揭示了二次喷丸参数与42CrMo钢零件表面完整性之间的影响规律,为二次喷丸的工业应用提供了一定的参考意义。     

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。     

表面处理状态对Fecralloy合金氧化膜完整性的影响

研究了表面粗糙度对Fecralloy (Fe 2 2Cr 5Al 0 .3Y ,质量分数 ,% )合金在 12 0 0℃空气中循环氧化生成表面氧化膜完整性的影响。采用SEM技术着重研究了合金表面氧化膜的性质和特点。结果表明合金表面粗糙度对Fecralloy合金表面氧化膜的完整性有重要的影响 ,初始合金表面粗糙度越大 ,氧化膜越容易开裂。讨论了合金表面粗糙度对氧化膜开裂行为的影响。     

微细超声辅助高速微槽铣削加工工艺研究

为了提高6061铝合金板微铣削槽加工质量,搭建一种轴向超声振动辅助高速微槽铣削实验装置。设计单因素实验探究主轴转速、超声功率、进给率三个因素对微槽顺铣侧毛刺长度和底面粗糙度的影响规律。制定正交实验寻求主轴转速、超声功率、进给率三个因素的共同作用对微槽底面粗糙度的影响效应,做显著性检验,寻找最优水平组合。实验结果表明:单因素实验中,相对高的主轴转速、适中的进给率、适中的超声功率铣削出的微槽顺铣侧毛刺较少、毛刺长度较短,相对低的转速、相对小的进给率、适中的超声功率铣削出的微槽底面粗糙度较小。正交实验中,主轴转速和超声功率值的变化对微槽底面粗糙度影响显著,通过正交分析与方差分析,最终确定出最优水平组合。