基于FPGA的数控系统圆弧插补控制模块化设计

针对数据采样圆弧插补算法进给速度慢、加工效率低等问题,提出一种模拟可配置电子凸轮箱的插补方法,构建了圆弧插补算法模型。采用硬件描述语言设计圆弧插补模块,基于FPGA控制系统建立多轴联动的运动控制实验平台。实验数据表明:当圆弧路径的半径为10 000个脉冲当量时,电机运行的误差峰值为11.4个,误差为0.114%;当圆弧路径的半径为15 000个脉冲当量时,电机运行的误差峰值为13.2个,误差为0.088%。误差峰值出现在伺服电机换向时,是由其自身的机械特性和传动刚性所致。结果表明:电子凸轮箱式插补算法的插补轴并行独立,因此其速度快、精度高、可靠性强;通过调节各插补轴分量形成各类圆弧轨迹路径,因此方便、灵活且柔性高。     

五轴数控旋风铣削机床加工螺纹的误差补偿研究

基于小误差运动假设,分析了五轴旋风铣削机床误差运动和补偿运动间的相互关系,建立了考虑工件热胀冷缩时进行其空间5个误差量计算的数学模型,为五轴旋风铣床用于螺纹精加工时的误差实时插补提供了理论基础,也是建立考虑工件热变时通用五轴旋风铣床误差实时插补数学模型及以旋风铣削精加工质量为目标函数、约束于多变量的数学模型的第一步.     

基于角度逼近的马鞍形曲线自动焊接插补算法

介绍了马鞍形曲线自动焊接系统的工作原理、插补算法及软件实现.系统通过x,y,z三轴联动,控制焊枪实现马鞍形曲线焊缝的自动焊接.在基于角度逼近的平面圆弧插补算法的基础上,分析了马鞍形曲线空间几何特点,根据x,y,z三坐标的空间几何关系设计了一个插补决策.算法利用焊枪对马鞍形曲线焊缝在xOz平面内投影轨迹的回转联动y轴运动来拟合马鞍形曲线,从而解决了马鞍形曲线焊缝的自动焊接问题.由该算法实现的程序结构简单,易于实现,而且运行效率高,插补出的曲线均匀且误差小.     

IC芯片粘片机并联焊头机构的插补算法及误差分析

针对所设计的IC芯片粘片机的并联焊头机构,对其在平面上任意曲线的插补算法进行了分析.利用驱动轴的PVT插补规律和对分式原则对并联焊头机构运动轨迹的插补误差进行了计算,并通过Matlab软件进行了仿真.结果表明, 轨迹的插补误差与插补直线的斜率、所分的段数和焊头机构的位置有关.     

基于五轴联动数控系统刀具半径补偿的研究

在深入研究平面刀具半径补偿原理的基础上,推导出了一种适合直线插补的二维刀具半径补偿通用公式,并结合空间变换原理,将三维空间内的刀位点投影到二维平面内,确定半径补偿方向,得出了三维空间刀具半径补偿的算法。     

五轴联动圆弧非线性插补算法及其软件实现

以具有A、C旋转轴的刀具双摆动五轴机床为例,提出五轴联动数控机床的空间圆弧非线性时间分割插补算法.详细研究五轴联动中的平动和旋转运动的联动原理,利用齐次变换矩阵求取圆弧插补点的空间坐标.通过插补点的空间坐标,逆求出刀轴的旋转量,进而求取转角补偿位移,并将其叠加至平动位移上,在每一个插补步骤中进行补偿,从而实现空间圆弧的时间分割插补算法.最后利用Visual C++6.0编写该算法的仿真软件,验证该插补算法的正确性.五轴联动圆弧非线性插补算法适用于五轴联动数控机床中任意空间圆弧的插补.该算法计算简单,结果精确,刀具移动平稳.     

多轴联动电火花加工数控系统可逆插补研究

为了实现电火花加工中的多轴联动可逆插补,利用改进的逐点比较法开发了可逆直线插补算法;利用改进的单步追踪法开发了可逆圆弧插补算法;以二轴联动插补为基础,派生得到了多轴联动插补算法.利用文中研究的多轴联动可逆插补算法,开发出了5轴联动可逆插补算法,应用于5轴联动电火花加工数控系统中,并运用该数控系统进行了带冠整体式涡轮盘的加工实验.实验表明该算法是一种精确严格的多轴联动可逆插补算法,非常适用于多轴联动电火花加工数控系统.     

中凸变椭圆活塞曲面插补算法研究

活塞是内燃机的关键零部件,型面通常设计成中凸变椭圆型.对比了一般的等精度圆弧逼近法和等角度圆弧逼近法等横截面插补算法之后,提出一种更为准确的轴截面的插补算法——极坐标插补算法,这种算法计算简单,运算精度高.在此基础上,在x轴上附加直线电机控制刀具做高频往复运动,实现椭圆截面的加工.     

一种新的逐点比较法圆弧插补算法的研究

传统的逐点比较法在圆弧插补中的误差δ≤1个脉冲当量,且输出到各个轴的脉冲不均匀,为了解决这个问题,提出了一种新的逐点比较圆弧插补法。新插补算法的理论误差δ≤0.447 2个脉冲当量,并对新插补算法进行了实例验证。结果表明:在半径为6的圆弧上进行插补时,其最大误差为δ=0.343个脉冲当量,且脉冲分配也更加均匀。     

梯形速度控制变插补周期的实时插补算法研究

提出了基于梯形速度控制的变插补周期实时插补算法.在固定插补步长条件下,依据直线加减速算法,确定出加速段、恒速段和减速段的插补次数,进而生成变化的进给速度和相应的插补周期;同时,形成各坐标轴的运动增量.仿真实例结果表明,该算法可有效地控制加工精度,充分发挥联动各轴的加速能力,有效缩短加减速过程时间,且易于在CNC系统中实现.     

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 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.     

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.     

Formulas of Tension of Continuous Rolling Process

The development of computer controlled continuous rolling process calls for a mathematical expression that can express the inequality condition of "constant flow". Tension is the link of the continuous rolling process. From the condition of dynamic equilibrium, a differential equation of tension is given out. On the basis of the physical rules established from the industrial practice and experimental studies, the law of volume constancy, the linear relation of forward slip and tension, the state equation of continuous rolling, the formula of dynamic tension, and the formula of static tension have been obtained. These formulae reflect the functional relations between tensions, thickness, roll velocity, and time in the continuous rolling process. It is implied that the continuous rolling process is a gradually steady, controllable, and measurable dynamic system. An assumption of predicting the thickness of a steel plate using these tension formulae is also put forward.