CA6140机床主轴有限元分析

在机械加工中，CA6140机床的主轴在转动情况下，变形十分复杂，是造成工件尺寸误差和形状误差的主要原因之一，论文通过建立CA6140机床主轴的几何模型，采用有限元分析方法，分析了机床主轴在加工过程中的变形和应力，依据有限元分析结果，提出了减小机床加工误差的方法。     

基于CAE和神经网络的切削参数优化

提出了一种以变形加工误差为约束的基于有限元分析和神经网络的切削参数优化方法.针对复杂工件夹具系统在切削过程中的变形问题进行有限元刚度计算,然后通过神经网络的方法拟合切削参数和工件夹具系统变形误差之间的关系.并以加工生产效率最大化为目标,在保证加工精度的前提下优化切削参数.从而实现以工艺成本最小化来提高零件的加工精度.     

某型数控机床主轴系统回转误差动态测试研究

高速主轴的回转误差运动直接影响到被加工零件的加工精度与产品的使用寿命。为了对数控机床的加工性能进行合理评价,分析了同步径向误差运动与工件圆度以及异步误差运动与工件表面粗糙度之间的关系,并采用美国Lion Precision公司开发的主轴误差分析仪对某型数控机床的主轴系统进行回转误差及漂移的测量,根据测量结果对所测主轴加工性能进行评价,为实际生产加工提供了参考。     

立式磨削工艺系统建模方法及仿真研究

为研究磨削行为和磨削误差,提出以立式磨削工艺系统为分析对象的误差分析模型。该模型由转台、工件、砂轮、主轴等零部件组成。分析转速比、工件初始圆度误差相位、磨削时间和主轴回转误差对磨削精度的影响规律。结果表明：该系统能预测磨削行为和磨削误差;当转速比为整数时,磨削精度随着转速比的增大而提高;当转速比不是整数时,变化情况更加复杂;工件初始圆度误差的相位对最终的加工圆度不会产生影响;随着磨削的进行,工件圆度误差开始降低得很快,随后降低趋势逐渐变缓;在主轴误差的组成频率中,3阶误差导致的圆度误差最大,2阶误差导致的圆度误差最小。     

纵向旋转切削加工对环形零件畸变的影响

通过旋转试验和有限元分析介绍了工件在切削加工过程中产生的畸变情况，分析了工件的装夹方式、切削速度、切削深度和进刀量对100Cr6钢环圆度的影响。通过去应力退火释放冷加工诱发的残余应力后工件的圆度与切削参数有关。另外测试了被试验环的表面残余应力，其表面残余应力与装夹方式有关。将测量的装夹力作为计算参数输入，通过有限元分析方法测试了装夹方式对工件变形的影响。协同测量结果示出了装夹方式影响工件变形的一个主要因素，表面残余应力与工件的径向变形有关，最大的拉伸应力位于夹口位置。旋转切削试验结果表明，提高切削速度圆度会稍有增加；随着切削深度的加大，圆度呈下降趋势，尽管切削力增加了；进给量的增加会导致更高的切削力，因此圆度值也增加；常规的去应力退火可使被加工环的圆度值增加。     

薄壁零件装夹方案设计与优化

针对薄壁零件刚性差,制造过程中在夹具夹紧力和切削力的作用下,容易产生加工变形,严重影响加工精度和表面质量等问题,分析和阐述了提高薄壁零件加工精度的装夹设计方法.研究了基于遗传算法和有限元方法的薄壁零件夹具布局和夹紧力的同步优化设计方法,以一壳体薄壁零件为例,进行了其夹具的装夹方案设计以及夹具布局和夹紧力的同步优化.结果表明该优化方法可以有效地降低由于装夹不当所引起的工件变形程度, 提高工件的加工精度.     

工艺系统变形分析及精度控制技术研究

工艺系统的变形是引起工件加工误差的主要原因.本文首先分析了工件加工时的主要误差来源,分别从机床、刀具、夹具和工件变形分析四个方面全面地阐述了目前国内外关于工艺系统变形分析的研究现状,并总结了国内外常用的工件加工精度控制措施.     

电火花成型机床的几种常见热变形及防治方法

机床加工误差中有相当的一部分是由热变形引起的。在温度场的影响下,机床各部件逐渐变形和移位,主要是主轴对工作台的垂直度发生变化,亦即电极相对工件的位置在不断变化,从而造成加工后型胫畸变。热变形的问题     

真空吸附铣削夹具的设计及其应用

工件变形是影响薄板零件加工精度的主要问题。采用高速铣削加工可减小切削力、切削热、切削振动等产生的工件变形;利用真空吸附铣削夹具装夹工件,使其受到均匀分布的夹紧力,可大大减小因夹紧力造成的工件变形,提高零件的加工精度和表面粗糙度。在介绍真空吸附夹具结构设计与工作原理的基础上,重点阐述薄板零件高速铣削加工真空吸附夹具的设计要点及其应用。     

一种主轴回转误差测量方法的研究

主轴回转误差是影响机床加工精度的重要因素,针对主轴回转误差的产生和测量方法进行分析和研究。在此基础上,采用了一种优化算法——线位移四点法矩阵算法对主轴回转误差进行分离,来代替传统傅里叶变换实现圆度误差分离。采用最小二乘法和圆图像误差值对分离后的主轴回转误差进行评定。对测量数据进行处理,得到的结果精度较高,可以对主轴回转误差实现有效分离。     

Effects of Post-weld Heat Treatment on Microstructure,Mechanical Properties and the Role of Weld Reinforcement in 2219 Aluminum Alloy TIG-Welded Joints

In as-welded state, each region of 2219 aluminum alloy TIG-welded joint shows diff erent microstructure and microhardness due to the diff erent welding heat cycles and the resulting evolution of second phases. After the post-weld heat treatment, both the amount and the size of the eutectic structure or θ phases decreased. Correspondingly, both the Cu content in α-Al matrix and the microhardness increased to a similar level in each region of the joint, and the tensile strength of the entire joint was greatly improved. Post-weld heat treatment played the role of solid solution strengthening and aging strengthening. After the post-weld heat treatment, the weld performance became similar to other regions, but weld reinforcements lost their reinforcing eff ect on the weld and their existence was more of an adverse eff ect. The joint without weld reinforcements after the post-weld heat treatment had the optimal tensile properties, and the specimens randomly crack in the weld zone.     

The First Phase of the SRIF Industrialized Base in ＂West Area＂ Has Been Put into Operation

After nearly two years＇ tense construction, the first phase of industrialized base of Shenyang Research Institute of Foundry （SRIF）, located at the Tiexi Casting and Forging Industrial Park in the west of Tiexi District, has now been completed and formally put into operation.     

新型的治疗阿尔茨海默氏症药物(1-二甲基磷酰基-2,2,2-三氯)-乙基-1-醇烟酸醋对体外神经细胞的作用

目的: 观察本实验室合成的一种治疗阿尔茨海默氏症(AD)的药物(1-二甲基磷酰基-2, 2, 2 -三氯)-乙基^-1-醇烟酸醋(NMF),对体外培养的皮层神经细胞活性的影响以及对海人藻酸(KA)所致的神经损伤的保护作用。方法: 采用体外培养皮层神经元的方法,解剖分离 15 d胚胎小鼠皮层神经细胞, 接种于 96孔板,48 h 后加药并培养 72 h,以 MIT 法 观察 NMF 对小鼠皮层神经细胞活性的影响;同时将接种于 24 孔板的细胞预先给予 NMF,d 3 时加或不加KA处理后,以台盼蓝染色鉴别并计数死、活细胞,可得出细胞的存活率。结果: NMF 明显促进胎鼠皮层神经元活性,其中 NMF1、0. 1、10nmol·L^-1促进神经元活性增殖率分别高达 34.7%、37.4%、36. 7%, NMF 明显促进正常胎鼠皮层神经元存活卒,与对照组比较,10nmol·L^-1 NMF 对皮层神经元的存活率分别提高 39.3%、73.5%。 NMF能显著 对抗 KA 所致的神经元损伤,与 KA 损伤组相比, NMF0.1、10、10nmol·L^-1对损伤皮层神经元的保护率分别为 77.30%、80.10%、84.15%。结论: NMF 明 显促进胎鼠皮层神经元的洁性、提高正常皮层神经元,的存活卒,并能有效地保护KA所致的神经元损伤,提示 NMF 是一种很有潜力的治疗 AD 的药物。     

Three-Dimensional Growth of Coherent Ferrite in Austenite: A Molecular Dynamics Study

Coherent second phase often exhibits anisotropic morphology with specifi c orientations with respect to both the second and the matrix phases. As a key feature of microstructure, the morphology of the coherent particles is essential for understanding the second-phase strengthening eff ect in various industrial alloys. This letter reports anisotropic growth of coherent ferrite from austenite matrix in pure iron based on molecular dynamics simulation. We found that the ferrite grain tends to grow into an elongated plate-like shape, independent of its initial confi guration. The fi nal shape of the ferrite is closely related to the misfi t between the two phases, with the longest direction and the broad facet of the plate being, respectively, consistent with the best matching direction and the best matching plane calculated via the Burgers vector content(BVC) method. The strain energy calculation in the framework of Eshelby's inclusion theory verifi es that the simulated orientation of the coherent ferrite is energetically favorable. It is anticipated that the BVC method will be applicable in analysis of anisotropic growth and morphology of coherent second phase in other phase transformation systems.     

Effect of Rare Earth Doping on Impedance,Modulus and Conductivity Properties of Multiferroic Composites:0.5(BiLa_xFe_(1-x)O_3)–0.5(PbTiO_3)

The Lanthanum-doped bismuth ferrite–lead titanate compositions of 0.5(Bi LaxFe1-xO3)–0.5(Pb Ti O3)(x = 0.05,0.10,0.15,0.20)(BLxF1-x-PT) were prepared by mixed oxide method.Structural characterization was performed by X-ray diffraction and shows a tetragonal structure at room temperature.The lattice parameter c/a ratio decreases with increasing of La(x = 0.05–0.20) concentration of the composites.The effect of charge carrier/ion hopping mechanism,conductivity,relaxation process and impedance parameters was studied using an impedance analyzer in a wide frequency range(102–106Hz) at different temperatures.The nature of Nyquist plot confirms the presence of bulk effects only,and non-Debye type of relaxation processes occurs in the composites.The electrical modulus exhibits an important role of the hopping mechanism in the electrical transport process of the materials.The ac conductivity and dc conductivity of the materials were studied,and the activation energy found to be 0.81,0.77,0.76 and 0.74 e V for all compositions of x = 0.05–0.20 at different temperatures(200–300 °C).     

Quantitative Analysis of the Crystallographic Orientation Relationship Between the Martensite and Austenite in Quenching–Partitioning–Tempering Steels

The orientation relationships(ORs)between the martensite and the retained austenite in low-and medium-carbon steels after quenching–partitioning–tempering process were studied in this work.The ORs in the studied steels are identified by selected-area electron diffraction(SAED)as either K–S or N–W ORs.Meanwhile,the ORs were also studied based on numerical fitting of electron backscatter diffraction data method suggested by Miyamoto.The simulated K–S and N–W ORs in the low-index directions generally do not well coincide with the experimental pole figure,which may be attributed to both the orientation spread from the ideal variant orientations and high symmetry of the low-index directions.However,the simulated results coincide well with experimental pole figures in the high-index directions{123}_(bcc).A modified method with simplicity based on Miyamoto’s work was proposed.The results indicate that the ORs determined by modified method are similar to those determined by Miyamoto’method,that is,the OR is near K–S OR for the low-carbon Q–P–T steel,and with the increase of carbon content,the OR is closer to N–W OR in medium-carbon Q–P–T steel.     

Effect of Short-Time Aging on the Pitting Corrosion Behavior of a Novel Lean Duplex Stainless Steel 2002

The effect of short-time aging in the temperature range between 400 and 1000 °C on the pitting corrosion behavior and mechanical property of a novel lean duplex stainless steel(LDSS) 2002 was investigated through the potentiostatic critical pitting temperature(CPT) tests and the Charpy impact tests. Both the pitting corrosion resistance and the toughness of aged specimens degraded due to the precipitation of detrimental secondary phases and the most significant reduction of CPT and impact energy emerged at 650 °C concurrently. The CPT of LDSS 2002 specimen aged at 650 °C decreased by 28 °C, and the impact energy dropped from 69 to 29 J/cm~2 compared with the solution-annealed sample. Transmission electron microscopy characterization showed that the main precipitates in LDSS 2002 were Cr_2N and M_(23)C_6 along the ferrite–austenite grain boundaries.     

Information for Contributors

正The Transactions of Nonferrous Metals Society of China,founded in 1991 and sponsored by The Nonferrous Metals Society of China,is published monthly now and mainly contains reports of original research which reflect the new progresses in the field of nonferrous metals science and technology,including mineral processing,extraction metallurgy,metallic materials and heat treatments,metal working,physical metallurgy,powder metallurgy,with the emphasis     

Preface

<正>We are pleased to present this Special Issue of Transactions of Nonferrous Metals Society of China containing selected papers from the First Asian Conference on Aluminum Alloys(ACAA-2013),held in Beijing,China,13–17 October 2013.This conference has been initiated,with approval of     

Information for Contributors

The Transactions of Nonferrous Metals Society of China, founded in 1991 and sponsored by The Nonferrous Metals Society of China, is published monthly now and mainly contains reports of original research which reflect the new progresses in the field of nonferrous metals science and technology, including mineral processing, extraction metallurgy, metallic materials and heat treatments, metal working, physical metallurgy, powder metallurgy, with the emphasis on fundamental science. It is the unique preeminent publication in English for scientists, engineers, under/post-graduates on the field of nonferrous metals industry. This journal is covered by many famous abstract/index systems and databases such as SCI Expanded, Ei Compendex Plus, 1NSPEC, CA, METADEX, AJ and JICST.