楔形气隙结构对永磁同步电主轴转矩和径向力影响的分析

为了提高永磁同步电主轴电磁转矩,减小振动噪声,提出了一种楔形气隙结构。文中对楔形气隙永磁同步电主轴的电磁转矩进行了解析分析。利用有限元软件对均匀气隙和楔形气隙永磁同步电主轴模型进行了仿真分析,将以上两种气隙结构模型的电主轴转矩和径向力进行了对比,发现楔形气隙结构和均匀气隙结构的永磁同步电主轴相比电磁转矩幅值增加较大,径向力幅值显著减小。并得出楔形气隙结构对提高永磁同步电主轴转矩密度、减小振动噪声有明显的作用。     

一种永磁同步电主轴转矩脉动和电磁力波的抑制方法

针对磁极为平行充磁且两边平行的表面式永磁同步电主轴存在转矩脉动和径向电磁力波的问题,提出一种磁极结构优化方法以抑制转矩脉动和径向电磁力波。基于等效面电流法建立磁极表面半径为任意值的永磁同步电主轴转子气隙磁场的解析模型;综合研究转子气隙磁场对定子开槽电主轴转矩脉动、径向电磁力波的影响;在最小气隙长度不变的前提下,确立优化目标(气隙磁通密度的谐波和幅值),并通过迭代计算的方式得到满足不同优化目标的永磁体磁极结构方案(方案一结构和方案二结构);最后,通过有限元法验证转子气隙磁场解析模型的有效性,并对原结构电主轴、方案一结构电主轴和方案二结构电主轴的转子气隙磁场谐波、转矩脉动、齿槽转矩、平均转矩和径向电磁力波进行对比分析。结果表明:该优化方法可以得到满足不同优化目标的永磁体磁极结构方案,实现原电主轴指定阶次磁通密度谐波、转矩脉动和径向电磁力波的综合抑制。     

永磁同步电主轴定子齿形对转矩脉动影响

文中提出了利用有限元法来减小永磁同步电主轴转矩脉动的一种方法。通过建立仿真模型来分析计算电主轴的磁场分布和气隙电磁力密度。在分析过程中,以4级18槽电主轴为例,通过改变定子齿形结构来降低电主轴转矩脉动,进而降低电主轴的噪声和振动。综合考虑影响转矩脉动的因素,在不影响永磁同步电机主轴运行性能的前提下,设置合理的定子齿形结构,可以在一定程度上削弱转矩脉动。此方法为永磁同步电主轴的优化设计提供了参考。     

基于有限元和实验的永磁同步电主轴模态分析

振动和噪声是评价永磁同步电主轴运行平稳性的一个重要指标,避免电磁力与定子共振是电主轴动态设计过程中必须要考虑的因素。因此较准确地确定定子的固有频率就显得尤为重要。本文对一台功率为9.5 k W的永磁同步电主轴的模态进行了有限元计算和实验测试。通过对各部件进行等效简化,建立了有限元仿真模型。其中对绕组进行两种方式的处理:一是建立简化模型;二是将其质量进行等效处理。之后对电主轴定子结构和整机装配体电主轴单元的模态分别进行了有限元计算。最后借助丹麦BK振动声学测试系统对电主轴进行实验模态分析,验证计算结果的准确性。     

永磁同步电主轴定子齿形状对转矩脉动的影响分析

文中提出了一种基于有限元法来减少永磁同步电主轴转矩脉动的方法。通过建立永磁同步电主轴的仿真模型来完成电主轴磁场分布和气隙电磁力密度的计算。在分析过程中,通过改变定子齿结构来减少电主轴的转矩脉动,进而减少电主轴的噪声与振动,提高电主轴运行的平稳性。通过综合考虑影响电主轴转矩脉动的因素,合理设置定子齿参数,在不影响永磁同步电主轴运行性能的前提下,转矩脉动可以得到了一定程度的削弱。该方法为永磁同步电主轴的优化设计提供了参考。     

转子结构对永磁同步电主轴转矩脉动的影响

齿槽转矩是由转子与定子齿间电磁力的切向分量所构成。齿槽转矩的变化引起转矩脉动,影响永磁同步电主轴稳定性。不同的转子表面结构,会引起气隙的不均匀,影响气隙磁场分布,导致磁导发生较大的变化,进而影响转矩脉动的大小。对永磁同步电主轴进行了有限元仿真分析,通过改变转子表面结构减小了永磁同步电主轴的转矩脉动。结果表明:合理设计内置式永磁同步电主轴的转子表面结构,可以有效地减小转矩脉动对电主轴的影响,提高系统的工作精度,并且不会减小额定转矩。     

气隙形状对永磁同步电主轴齿槽转矩的影响

齿槽转矩是由于谐波磁势与气隙磁导的相互作用产生,齿槽转矩的变化引起电机振动与噪声,影响永磁同步电主轴的稳定性。提出了一种削弱永磁同步电主轴齿槽转矩的方法,可以提高高档数控机床的工作精度。借助ANSYS有限元分析软件,建立了永磁体同步电主轴有限元模型,分析其电磁特性。通过改变非均匀气隙中不同的最长气隙长度与其偏移位置角度气隙形状参数,总结出齿槽转矩和额定转矩的变化规律。依据最佳参数设计永磁同步电主轴,可有效地降低齿槽转矩。研究表明:同一最长气隙长度下,随着偏移位置角度的增加,齿槽转矩先下降,然后开始增加;而额定转矩是先呈现上升趋势,后逐渐开始下降。合理设计永磁同步电主轴气隙形状可以有效地削弱齿槽转矩,且不会减小额定转矩值。     

永磁同步电主轴磁极结构对气隙磁密分布的影响

永磁同步电主轴设计的关键因素之一是如何确定产生所需气隙磁密的永磁体的尺寸。传统的永磁体尺寸设计采用经验公式估算,不具有准确性。文章阐述不同磁体尺寸对三种磁极结构径向磁通永磁同步电主轴气隙磁密的影响。借助于三种磁极结构的静态有限元模型仿真,揭示出永磁体体积和产生磁通的永磁体面积之间的直接关系。因此,一旦确定了最小永磁体体积,就可以很容易的计算出产生磁通的永磁体面积。此技术也可用来设计转子截面积有限的异步启动永磁同步电主轴。     

永磁体削角参数对永磁同步电主轴齿槽转矩影响的研究

齿槽转矩是由于永磁体和有槽电枢铁心的相互作用产生的,齿槽转矩的变化会引起电机振动与噪声,影响永磁同步电主轴的稳定性。文章提出了一种削弱表贴式永磁同步电主轴齿槽转矩的方法,可以提高数控机床的工作精度。借助ANSYS有限元分析软件,建立了表贴式永磁同步电主轴的有限元模型,通过优化永磁体削角参数减小了永磁同步电主轴的齿槽转矩。研究表明:对永磁体进行三角形削角,可有效减小齿槽转矩脉动。     

永磁体廓形对永磁同步电主轴转矩脉动的影响

文章分析了永磁体表面廓形对永磁同步电主轴转矩脉动及噪声的影响。通过在永磁体表面进行开槽来降低转矩脉动,以达到抑制振动噪声的目的。槽形包括圆弧形、矩形、三角形、梯形等形状。其中梯形槽形状在不减少平均扭矩的情况下显著减少了转矩脉动。建立永磁体表面形状改进前后的三维模型,完成了谐响应和声场的计算,并对计算结果进行对比分析。指出该方法可有效地降低永磁同步电主轴转矩脉动和噪声。     

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.     

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。     

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.     

THERMODYNAMICS STUDY ON THE DECOMPOSITION OF CHROMITE WITH KOH

Institute of Process Engineering, Chinese Academy of Sciences, China, has proposed a method for oxidative leaching of chromite with potassium hydroxide. Understanding the mechanism of chromite decomposition, especially in the potassium hydroxide fusion, is important for the optimization of the operating parameters of the oxidative leaching process. A traditional thermodynamic method is proposed and the thermal decomposition and the reaction decomposition during the oxidative leaching of chromite with KOH and oxygen is discussed, which suggests that chromite is mainly destroyed by reactions with KOH and oxygen. Meanwhile, equilibrium of the main reactions of the above process was calculated at different temperatures and oxygen partial pressures. The stable zones of productions, namely, K2CrO4 and Fe2O3, increase with the decrease of temperature, which indicates that higher temperature is not beneficial to thermodynamic reactions. In addition, a comparison of the general alkali methods is carried out, and it is concluded that the KOH leaching process is thermodynamically superior to the conventional chromate production process.     

INFLUENCE OF HEAT TREATMENT ON DAMPING BEHAVIOUR OF THE MAGNESIUM WROUGHT ALLOY AZ61

The effect of isochronal heat treatments for 1h on variation of damping, hardness and microstructural change of the magnesium wrought alloy AZ61 was investigated. Damping and hardness behaviour could be attributed to the evolution of precipitation process. The influence of precipitation on damping behaviour was explained in the framework of the dislocation string model of Granato and Lücke.     

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.     

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.