高速铣削加工表面位置误差的频域分析（英文）

在高速铣削加工过程中,提高轴向切削深度和主轴转速可以获得较高的材料去除率,然而限制轴向切削深度提高的一个因素是加工颤振。高速铣削系统动态失稳可能导致加工零件的表面几何精度偏差。分析高速铣削的表面位置误差对表征切削过程、刀具寿命估算和加工优化都起着重要作用。因此,在不考虑再生颤振影响的前提下,提出了一种数值分析和加工实验相结合的方法来研究表面位置误差。首先,构建了高速铣削加工过程模型,然后建立了动态铣削力模型,并推导了表面位置误差的分析方法。通过数值分析和铣削实验相结合,得到了高速铣削加工的稳定性叶瓣图。接下来,研究了逆铣削加工过程的表面位置误差,并详细分析了主轴转速和轴向切削位置对表面位置误差的影响规律。最后,把稳定性叶瓣和表面位置误差数据组合在同一个图里得到了高速铣削加工的综合分析图。借助综合分析图,能预测表面位置误差和优化高速铣削的工艺条件。     

MDH80加工中心铣削稳定性研究

为了提高发动机缸体与缸盖结合面的表面加工质量,研究了铣削加工过程中的颤振稳定性问题。进行了刀具—主轴锤击模态试验和铣削力仿真实验,获得了所用刀具的低阶模态参数及铣削力系数。构建了铣削颤振的稳定性叶瓣图,用于指导切削参数的选择和优化。通过该方法可以选取合适的主轴转速和切削深度,避免加工过程中颤振的发生,提高工件表面的加工精度,并对加工刀具及机床本身有保护作用,可提高其使用寿命。     

高速铣削模具钢3Cr2NiMo表面粗糙度试验研究

采用单因素试验法和正交试验法,在高速加工中心上对模具钢3Cr2NiMo进行切削试验,通过改变影响加工过程的切削参数:主轴转速、进给速度、轴向切削深度和径向切削深度,研究了影响工件加工表面粗糙度值程度的因素。结果表明:增大机床的主轴转速,粗糙度值显著降低,而增大进给速度、轴向铣削深度,粗糙度值增大,但增大的幅度不同,径向铣削深度的影响不明显。     

薄壁件铣削系统动态特性及稳定性分析

颤振失稳现象是铣削过程中降低加工表面质量的一种不利因素,针对此问题采用颤振稳定性解析算法建立铣削过程的动态铣削模型,以钛合金ZTC4/42C薄壁件铣削参数作为研究对象,通过仿真绘制出转速和切削深度相关的稳定性叶瓣图;其次,分别对影响铣削稳定性的机床系统的模态因素、刀具几何参数和材料特性进行了分析,研究结果可以为钛合金薄壁件铣削加工提供理论支持。轴承接触点的刚度值与切削稳定性所需的刀尖点频响函数信息密切相关,采用有限元软件对主轴系统进行动态特性研究,借助仿真分析得到刚度与刀尖点频响函数之间的内在关系。     

基于切削参数的高速铣削系统稳定性研究

切削中的振动对加工质量有很大的影响,通过高速铣削试验及仿真分析,对基于工艺参数和刀具参数的高速铣削系统稳定性进行研究,得到了主轴转速、进给量、切削深度、刀具几何参数等对切削颤振系统稳定性的影响规律。试验所得结果为高速铣削加工切削用量的合理选择,特别是加工参数的优化提供了参考。     

旋转超声振动铣削Cr12MoV轴向切削力与表面粗糙度研究

为研究切削参数对切削效果的影响,将旋转超声振动铣削引入Cr12MoV模具钢铣削过程中;通过正交试验设计开展切削试验,从轴向平均切削力和表面粗糙度两方面研究了旋转超声振动铣削参数选择对Cr12MoV模具钢加工的影响.结果表明:在旋转超声振动辅助铣削Cr12MoV模具钢的过程中,主轴转速和切削深度对轴向平均切削力和表面粗糙度影响最大;在主轴转速2000 r/min、切削深度0.6 mm时,可获得较小的轴向平均切削力和较好的表面粗糙度;将旋转超声振动应用到Cr12MoV模具钢铣削过程中,能获得较好的加工效果.     

新型陶瓷托辊专用磨床磨削颤振稳定性分析

为了避免陶瓷托辊专用磨床在加工过程中产生颤振而降低磨削质量,根据陶瓷托辊磨削加工机制,建立了陶瓷托辊磨削加工过程数学模型,通过MATLAB计算分析得出磨削深度与主轴转速的稳定性叶瓣图,确定了陶瓷托辊磨床在磨削深度低于4 mm时可无颤振稳定磨削。研究结果为陶瓷托辊专用磨床稳定磨削加工提供了参考。     

五轴机床刀尖点频响特性及切削稳定域位置的演变

五轴机床在航空航天领域大型曲面零件加工中应用极其广泛,其高速、高精度和大材料去除率的加工特点对加工稳定性提出了很高要求,影响五轴机床铣削稳定性的主要问题是切削颤振。通过对一台转摆头五轴机床进行动力学性能测试,对比分析主轴系统在不同位置和转摆头在不同姿态下刀尖点的频响特性,得出刀尖点频响特性随位置的演变规律。以频域法构建切削稳定性叶瓣图,得到极限切深的位置演变规律。研究结果为五轴机床切削参数的优化提供了参考。     

基于斜角切削模型的铣削加工稳定性研究

针对零件加工过程中发生的颤振现象,结合大型A/B摆五轴龙门铣床,在斜角切削模型的基础上进行了铣削稳定性的研究。基于斜角切削的工作正交平面和法平面参考坐标系,引入切削力系数的修正形式;将切削刃微元在局部坐标系下进行切向、径向分解,经过坐标变换得到在整体坐标系下的切削分量,通过积分求和得到整个铣刀上的切削力。在此基础上采用完全离散解析法对颤振稳定域叶瓣图进行仿真,仿真结果表明,铣削过程中参数选取与颤振临界切削深度存在非线性关系;随着斜角切削刃倾角的增大,临界切削深度加深,稳定区域变大,铣削加工颤振的稳定性得到改善。     

变齿距铣刀高速微铣削的动态特性及稳定性研究

在高速微铣削加工过程中,提高生产效率和零件质量的需求日益强烈,这使得机床一直在系统的动态稳定性极限附近工作,而机床颤振的存在是限制微铣削加工生产率的主要障碍.基于颤振稳定性的准确预测,能采取一些措施来提高动态稳定性极限,例如通过改变铣刀结构.提出了数值分析与铣削实验相结合的方法,采用变齿距微铣刀来研究铣削加工的动态特性和稳定性.另外提出了采用时域仿真的输出力来表征加工稳定性的新方法,采用变齿距铣刀可以非常有效地提高某些速度范围的颤振稳定性.对于选定刀具的加工,这种方法可以用于加工优化,或在设计阶段预测刀具新型结构的性能.     

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.     

Rheology Feature of Simple Metal Melt

The rheology feature of Sb, Bi melt and alloys was studied using coaxial cylinder high-temperature viscometer. The results showed that the curve of torsion-rotational speed for Sb melt presents a linear relation in all measured temperature ranges, whereas for the Bi melt, the curve presents obvious non-Newtonian feature within the low temperature range and at relative high shear stress. The rheology feature of Sb80Bi20 and Sb20Bi80 alloy melts was well correlated with that of Sb and Bi, respectively. It is considered that the rheology behavior of Sb melt plays a crucial role in Sb80Bi20 alloy and that of Bi melt plays a crucial role in Sb20Bi80 alloy.     

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.     

INTRODUCTION TO PATENTS

The invention provides a method of making a mold which can reduce SOx generation rate while preventing decrease in hardening rate in the case of using sulfuric acid for a hardener composition. The method has a mixture step in which fire-resistant particles, a hardener composition and a binder composition are mixed to obtain a composition for a mold. The hardener composition contains sulfuric acid. In the mixture step, sodium carbonate is added. A molar ratio of the sulfuric acid to the sodium carbonate is 0.5 or more and 4.0 or less.     

China Foundry Week 2014

China Foundry Week, hosted by the Foundry Institution of Chinese Mechanical Engineering Society （FICMES） each year, is a large academic event in China. It is one of the ten high-impact activities sponsored by the Chinese Mechanical Engineering Society.     

17th Conference of Hydrodynamic and Electromechanical Control Engineering Call for papers

正1.Contents In order to promote the academic exchanges and technical communication of the research in the field of fluid power transmission and control,fluid control engineering specialized committee of the Chinese Society of Theoretical and Applied Mechanics will hold the 17th Conference of Hydrodynamic and Electromechanical Control Engineering on July 27-29,2014 in Tibet,Lhasa city.     

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.