五轴联动刀轴矢量插补优化算法

目的研究解决五轴联动机床旋转轴角度采用线性插补方式生成的加工轨迹,导致刀具姿态偏离所设计的理想平面,引发刀具姿态误差的问题,减少非线性误差,提高零件表面质量。方法首先对旋转轴角度线性插补方式引发刀具姿态误差的原理进行了分析,提出了一种刀轴矢量插补优化算法。然后在线性插补的基础上,根据提出的刀轴矢量插补优化算法保证首末点间的刀轴插补矢量始终位于首末刀轴矢量所构成的平面内,实现刀具姿态优化,并在MATLAB中对线性插补和矢量插补优化两种方式进行仿真分析,观测出对应方式下刀轴插补矢量的空间位置。最后利用叶片试件在AB型转台摆头类型机床上进行仿真和加工验证,对比两种刀轴矢量插补方式仿真数据。结果在VERICUT同等条件下仿真,刀轴矢量采用线性插补时,叶片进出汽边误差值分别为-0.218 66 mm和-0.312 58 mm;刀轴矢量插补优化后,叶片进出汽边误差值分别为-0.095 46 mm和-0.099 05 mm。刀具姿态经过插补优化算法后,叶片进出汽边的过切值明显降低。结论刀具姿态经过插补优化算法后,叶片过切值的大小和数目明显减少,使得非线性误差明显降低,从而提高了零件表面质量。     

工件旋转与刀轴摆动数控加工关键技术研究

研究工件旋转与刀轴摆动五轴联动数控加工过程中,进给轴之间的协调、插补方式的选取、刀轴矢量与转角和摆角间的换算、刀位点从工件坐标系向工作坐标系转换的坐标变换关系、刀轴摆动导致基准点与刀位点之间的位置补偿、后处理器开发和刀位文件的后处理等关键技术,为多轴联动数控加工编程技术提供了参考.     

Bézier曲线在五轴直线插补刀路优化中的应用

为了解决五轴机床直线插补过程中,机床抖动及进给轴速度与加速度不连续等实际问题,对五轴直线插补刀路转接光顺进行了研究。基于刀轴的球面坐标系与平面坐标系存在的数学关系,通过2个欧拉角表示刀轴矢量,将其转换为平面问题。针对刀位点与刀轴矢量,利用Bézier曲线对其同时进行转接光顺,提出了一种新的插补光顺思路。经过Bézier曲线转接光顺后的五轴直线插补路径,保证了直线轴和旋转轴速度与加速度没有突变。在模拟过程中共生成839个插补点,每个插补点所消耗的直接计算时间为0.186ms,能够满足实时性要求。在五轴龙门式雕铣机上进行验证,光顺后的速度和加速度没有超过最大约束值,验证了插补光顺思路的可行性。     

刀具摆角对复杂曲面轮廓精度的影响研究

目的通过优化五轴联动加工中刀具摆角参数,基于后置处理技术提高复杂零件表面加工的轮廓精度。方法针对回转轴非线性运动造成的刀具姿态误差过大会导致零件轮廓精度低,提出了一种摆角优化方法。首先,对回转轴线性插补产生的刀具姿态误差进行分析,控制回转角的摆动幅度大小和初始位置;其次,将线性插补后的刀轴矢量投射到理论上始末两点矢量构成的平面上获得新的插补矢量,通过线性插补刀轴矢量来优化刀具空间姿态;最后,以某叶轮试件通过仿真及实际加工实验进行了验证。结果通过摆角优化方法后,叶片轮廓与理论轮廓的轮廓误差由0.08 mm减小到0.04 mm,最大过切量也由0.03 mm减小到0.01 mm。刀具摆角优化后,能大大提高复杂曲面零件的轮廓精度。结论基于后置处理技术对五轴机床回转轴摆角进行优化,在通用算法基础上加载角度优化算法,开发专用的后置处理器处理G代码程序,是一种提高复杂曲面加工轮廓精度的可行措施。实验验证了该方法的有效性。     

5轴加工奇异区域非线性误差控制方法

5轴数控机床在加工奇异区域时,由于旋转轴的剧烈变化导致产生较大的非线性误差,加工质量下降。针对这个问题,以A-C双转台机床为例,分析机床产生奇异现象的原因,提出检测5轴加工奇异区域的方案,通过对奇异区域相邻刀轴矢量之间进行插值处理,减小相邻刀轴的角度变化,使相邻刀位点之间的最大非线性误差小于机床允许的最大非线性误差。用MATLAB对比插值前后5轴机床转角和非线性误差的变化,证明该方法可以降低C轴的过大转角同时减小非线性误差。     

基于运动学约束的刀轴矢量优化研究

针对五轴数控加工中由于避免全局干涉而带来的刀轴矢量变化过大的问题,提出了向前、向后修正的平缓过渡方法,优化刀轴矢量的变化。建立了机床旋转轴角速度约束条件,并且在每一刀触点处建立进给坐标系,通过在进给坐标系下调整已有刀轴矢量的倾角和摆角使得相邻刀触点间的刀轴矢量变化满足机床旋转轴运动学要求,保证刀具轨迹上进给率的连续性。算法仿真和算例分析表明,所提出的方法合理可行,能使刀轴矢量变化光顺,保证了加工过程的平稳和高效。     

五坐标加工步长计算

五坐标曲面加工的理论刀具轨迹是由刀具与零件曲面的啮合关系所确定的非线性连续曲线，由此而得的机床各运动轴的理想联动规律是复杂的非线性关系，但由于目前的CNC在多轴联动控制时，一般只具有线性插补功能，理论的非线性连续曲线只能以一系列小线性段进行离散逼近后，再由CNC机床控制各运动轴作五维线性插补来实现被加工曲面的近似包络成型，由此而导致原理性的加工误差，在数控加工中，刀具在机床坐标系下的运动根据与被加工曲面的相对关系有二个方向，一是走刀轨 迹的方向，称为走刀方向，其在此方向上在一个插补周期内所移动的距离称为走刀步长。另一个是在走刀轨迹增量的方向，称为切削带步长，下面讨论这两个方向刀具的所能够移动的距离与误差的关系和进行计算。     

侧铣加工刀位轨迹优化算法研究

针对非可展直纹面侧铣精加工刀轴矢量计算中存在的问题,侧铣加工误差几何模型分析圆柱铣刀加工非可展直纹面误差产生的原因。以两点偏置法和三点偏置法等基本算法为基础,提高非可展直纹面类零件的加工精度,文章提出一种定点旋转寻求最优刀轴矢量组的计算方法,并且采用密切法进一步优化。通过优化算法使加工误差趋于最小,最终得到整体最优的刀轴轨迹。此方法与已有方法进行加工实验对比,从仿真结果可以看出明显提高了加工精度,对非可展直纹面侧铣加工提供一定的参考意义。     

基于刀具姿态控制的指令点插补算法

为克服五轴数控加工中忽略刀具姿态控制所带来的旋转轴速度和加速度不连续等问题,提出一种基于刀具姿态控制的五轴数控加工指令点插补算法。该算法根据给定的数控加工程序确定刀尖点位置集合和刀轴矢量集合,分别采用样条曲线对离散刀尖点和刀轴矢量进行拟合,得到刀尖点曲线和刀具姿态曲线,在此基础上进行指令点插补。实验结果表明,该算法能够将离散刀轴矢量拟合成位于单位球面的二阶连续曲线,保证旋转轴速度和加速度的连续性。     

五轴加工奇异问题及其处理方法

在五轴机床加工中,当刀轴矢量接近或平行于某一旋转轴(即奇异轴)而产生奇异问题,文章在分析奇异问题及其产生原因的基础上,提出一种奇异域检测的几何方法.这种方法可以根据始末位置刀轴矢量在未经插补的情况下,提前检测出刀轴是否经过奇异域及其类型,然后针对每种类型指定一种相应的插补算法,并且通过仿真实验.仿真结果表明该算法能够有效检测出加工中会出现的奇异问题并改善加工精度.     

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.     

Theoretical Analysis for the Motion and Temperature of Melt Droplets in Spray Degassing Process

The motion of melt droplets in spray degassing process was analyzed theoretically. The height of the treatment tank in spray degassing process could be determined by the results of theoretical calculation of motion of melt droplets. To know whether the melt droplets would solidify during spraying process, the balance temperature of melt droplets was also theoretically analyzed. Then proof experiments for theoretical results about temperature of melt droplets were carried. In comparison, the experimental results were nearly similar to the calculation results.     

Growth Kinetics of Single Inclusion Particle in Molten Melts

On the basis of the single-particle framework, a new theory on inclusion growth in metallurgical melts is developed to study the kinetics of inclusion growth on account of reaction and collision. The studies show that the early growth of inclusion depends on reaction growth and Brawnian motion collision, and where the former is decisive, the late growth depends on turbulence collision and Stokes＇ collision, and where the former is dominant; collision growth is very quick during the smelting process, lessened in the refining process, but nearly negligible in the continuous casting process.     

An Easy Way to Quantify the Adhesion Energy of Nanostructured Cu/X(X=Cr,Ta,Mo,Nb,Zr) Multilayer Films Adherent to Polyimide Substrates

An approach based on film buckling under simple uniaxial tensile testing was utilized in this paper to quantitatively estimate the interfacial energy of the nanostructured multilayer films(NMFs) adherent to flexible substrates. The interfacial energies of polyimide-supported NMFs are determined to be *5.0 J/m2 for Cu/Cr, *4.1 J/m2 for Cu/Ta,*2.8 J/m2 for Cu/Mo, *1.1 J/m2 for Cu/Nb, and *1.2 J/m2 for Cu/Zr NMFs. Furthermore, a linear relationship between the adhesion energy and the interfacial shear strength is clearly demonstrated for the Cu-based NMFs, which is highly indicative of the applicability and reliability of the modified models.     

High-Speed Friction Stir Welding of SiC_p/Al–Mg–Si–Cu Composite

A 17 vol% SiCp/Al–Mg–Si–Cu composite plate with a thickness of 3 mm was successfully friction stir welded(FSWed) at a very high welding speed of 2000 mm/min for the first time. Microstructural observation indicated that the coarsening of the precipitates was greatly inhibited in the heat-affected zone of the FSW joint at high welding speed, due to the significantly reduced peak temperature and duration at high temperature. Therefore, prominent enhancement of the hardness was achieved at the lowest hardness zone of the FSW joint at this high welding speed, which was similar to that of the nugget zone. Furthermore, the ultimate tensile strength of the joint was as high as 369 MPa, which was much higher than that obtained at low welding speed of 100 mm/min(298 MPa). This study provides an effective method to weld aluminum matrix composite with superior quality and high welding efficiency.     

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。     

A STUDY OF TEMPERATURE-DEPENDENT VALENCE BOND STRUCTURE OF TITANIUM

On the basis of energy and shape method for the determination of the valence bond (VB) structures of crystal, the valence bond structure of titanium is redetermined at room temperature and calculated in the whole temperature range of 0-1943K. The outer shell electronic distribution of Ti is e_c~(2.9907) · (s_c~(0.4980) d_c~(2.4927)) ef1.0093 in crystal. The temperature dependences of the VB structures of hcp and bcc phases are the same. The VB structures of hcp and bcc phases monotonically increase or decrease with the increase in temperature, but show discontinuous changes at the phase-transformation temperature 1155K.     

Structural Optimization of Electromagnetic Swirling Flow in Nozzle of Slab Continuous Casting

During the slab continuous casting process, the flow field of molten steel in the mold plays a decisive role in the quality of the slab. In this paper, electromagnetic swirling flow in nozzle technology is proposed to control the flow field in mold.This technology can drive molten steel to rotate inside the submerged entry nozzle by electromagnetic force, thereby controlling the flow field. This research shows that it can reduce the impact of molten steel on the bottom of nozzle and partly reduce the negative pressure at the upper part of nozzle outlet which is even eliminated by optimizing the structure and angle of nozzle. The area of heat flux of the mold wall becomes larger, and the crest value of heat flux gets lower than that without swirling in nozzle and any nozzle optimization. The meniscus fluctuates smoothly, and the flow velocity at the top surface is within a reasonable range. The temperature field distribution in the mold is uniform which was beneficial to the growth of equiaxed crystal and decreased element segregation.     

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).