直线电机驱动的冲压机床设计与研究北大核心

直线电机驱动的冲压机床可以实现"零传动",其结构简单,控制精度高,噪声小,是精密数控冲压机床的重要发展方向。通过对比分析,确定圆筒型直线电机作为冲压机床的动力源,并设计出机床的动力系统、缓冲机构等主要零部件;在此基础上,利用ADAMS软件对冲压过程进行仿真,得到了冲裁力仿真曲线,冲裁力为53 kN左右,满足设计要求;利用HyperMesh有限元软件分析了模架的刚度及床身的约束模态,通过求解计算分析,模架最大变形位置在下端面,为1.689×10^(-3)mm,床身最小固有频率为125.7 Hz,结果均满足机床使用要求。     

直线电机驱动的冲压机床设计与研究

直线电机驱动的冲压机床可以实现"零传动",其结构简单,控制精度高,噪声小,是精密数控冲压机床的重要发展方向。通过对比分析,确定圆筒型直线电机作为冲压机床的动力源,并设计出机床的动力系统、缓冲机构等主要零部件;在此基础上,利用ADAMS软件对冲压过程进行仿真,得到了冲裁力仿真曲线,冲裁力为53 kN左右,满足设计要求;利用HyperMesh有限元软件分析了模架的刚度及床身的约束模态,通过求解计算分析,模架最大变形位置在下端面,为1.689×10~(-3)mm,床身最小固有频率为125.7 Hz,结果均满足机床使用要求。     

直线电机驱动的冲压机床仿真、分析与控制研究

直线电机直接驱动的冲压机床具有“零传动”、无机械磨损、响应快、结构简单等特点,是精密冲压机床的重要发展方向之一。在设计直线电机驱动的冲压机床结构的基础上,利用 ADAMS 软件对简化后的冲床的工作过程进行了动力学仿真分析,得到了运动部件位移-时间、速度-时间、加速度-时间及冲压力-时间等曲线,其结果均与设计要求吻合;然后利用HyperMesh 有限元软件分析了冲床直接承载部件-模架的刚度,通过分析可知：设计的模架结构满足刚度使用要求;最后设计了冲压机床的控制系统。     

直线电机驱动的冲压机床仿真、分析与控制研究（英文）

直线电机直接驱动的冲压机床具有"零传动"、无机械磨损、响应快、结构简单等特点,是精密冲压机床的重要发展方向之一。在设计直线电机驱动的冲压机床结构的基础上,利用ADAMS软件对简化后的冲床的工作过程进行了动力学仿真分析,得到了运动部件位移-时间、速度-时间、加速度-时间及冲压力-时间等曲线,其结果均与设计要求吻合;然后利用HyperM esh有限元软件分析了冲床直接承载部件-模架的刚度,通过分析可知:设计的模架结构满足刚度使用要求;最后设计了冲压机床的控制系统。     

新型全自动板料冲裁模结构设计

为改变现有板料冲裁模生产中存在的自动化程度较低的人工送料和取件方式,对板料冲裁模结构设计进行了研究。从工艺方案的确定、模具结构尺寸计算和冲裁力计算等方面阐述了冲裁模设计的流程,设计了新型冲裁模具的自动送料和自动取件装置;并利用3D软件的运动仿真功能对板料冲裁过程进行了模拟。结果表明,设计出的新型自动冲裁模,可以实现冲裁过程中的送料、定位、成形和取件等工序的全自动化生产,极大地提高冲压加工的生产效率,实现冲压加工的完全自动化。     

利用弹性体使普通冲床实现精冲

在冲裁模架中设计安装弹性体。可使零件在普通冲裁时也受三向压直力的作用,从而在普通冲压设备上也能够生产出尺寸精度高、剪切面光洁度好的高精密零件。     

减小冲裁力及冲压噪声的研究

某冲压车间有３台０．１２ＭＮ冲床和２台０．４ＭＮ可倾斜开式冲床。几台冲床同时工作时，车间合成噪声达１１０ｄＢ（Ａ），对工人身心健康危害很大。在检修中还发现一台０．１２ＭＮ冲床曲柄铜套磨损过快；冲下来的料毛刺不齐，一边为０．１ｍｍ，另一边为０．０２ｍｍ。同时也测得这台冲床单机噪声为１０４ｄＢ（Ａ），把这些情况综合起来分析得出如下结论：（１）要减小冲压噪声，首先应减小冲裁力。（２）冲孔毛刺高度不均匀，是由于冲裁力过大，床身刚度满足不了工作要求，Ｃ型床身严重变型，上、下模中心相互倾斜促成的，所以，也要…     

有效降低厚板料冲裁模冲裁力的方法

介绍了厚板冲裁模冲裁力计算及通过波浪型刃口及阶梯型凸模的应用有效降低冲裁力,最终满足机床使用要求,并介绍了厚板修边冲孔模具结构的设计及模具的工作过程。     

基于UG平台的冲裁模自动设计研究

本文在深入研究和利用UG软件二次开发工具的基础上，充分考虑冲裁模的设计特点，研究了进行冲裁模自动设计的方法及其有关技术和过程；开发了进行冲裁模自动设计的模型系统。该系统能够帮助设计者完成从凸、凹模设计到模架选择及装配等一系列繁琐的工作，从而大幅度地缩短设计周期，降低设计者的劳动强度，减少设计过程可能出现的人为误差和失误，提升了冲裁模设计的智能化和自动化水平。     

基于BP神经网络的传力片冲裁凸模磨损仿真预测

以离合器盖总成中的传力片作为研究对象,借助Deform-3D仿真软件模拟了传力片冲裁过程中的凸模磨损情况,依据正交仿真试验的数据以及BP人工神经网络对传力片冲裁凸模的磨损量进行仿真预测。将冲裁间隙、凹模刃口圆角半径与冲裁速度作为BP神经网络的输入层,将冲裁凸模的最大磨损深度作为BP神经网络的输出层,建立3-12-1的3层BP神经网络。BP神经网络通过训练之后,仿真预测的最大误差为1.14%。基于正交试验的仿真数据对BP神经网络的性能进行检验,BP神经网络的仿真预测值与数值模拟值之间的误差为2.09%,并利用冲压级进模对BP神经网络的仿真预测值进行试验验证,两者之间的相对误差为8.25%,验证了BP人工神经网络应用于传力片冲裁凸模磨损仿真预测的准确性。     

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。     

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.     

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.