折弯机滑块的有限元分析及优化

为了建立统一的折弯机建模分析方法,形成亚威公司主要折弯机机型的刚性数据,便于设计人员掌握和精度分析.本文利用CosmosWorks分析软件,在分析折弯机滑块工作及受力情况的墓础上,建立滑块的有限元模型,进行仿真分析,找出结构中的薄弱环节,对其进行优化设计,最终确定优化方案.     

折弯机压力不均匀分布研究

本文用弹性力学理论分析了影响折弯精度的原因是折弯机的滑块及工作台弹性变形导致的压力分布不均匀.介绍了国内外三种挠度补偿方法.通过对本公司生产的液压补偿式折弯机进行有限元分析模拟,比较了补偿前后工作台的变形及压力分布情况.     

数值模拟在折弯机机械补偿装置设计中的应用

本文采用三维弹性接触有限元法对折弯机机械补偿装置补偿过程进行数值模拟,得到工作台上表面变形挠度曲线.通过与滑块下表面变形曲线的比较,修正机械补偿装置的设计尺寸,使得工作台和滑块的变形曲线有较高的吻合度,保证了折弯机的加工精度,对机械补偿装置设计有较大指导意义.     

折弯机滑块变形分析及实验测试

折弯机在折弯载荷作用下的变形直接影响折弯机的刚性,从而决定折弯机的折弯精度,而折弯载荷的确定是其中的关键问题。以某型数控折弯机为研究对象,采用Solid Works建立三维模型,利用DEFORM-3D有限元分析软件对折弯过程进行仿真,计算表明滑块在主要承受竖直方向折弯力的同时,还受到板料对滑块的水平推力。将仿真计算得到的折弯力施加到折弯机的有限元模型,获得了折弯机的整体变形规律。为了验证折弯机有限元计算结果的正确性,对折弯机滑块的变形进行了实验测试,试验测试值与有限元计算值比较接近,为进一步完善和优化折弯机结构提供了理论依据。     

大中型折弯机滑块外凸弯曲变形原因分析

提出了引起折弯机滑块外凸弯曲变形的主要原因以及计算此变形值的必要性,从理论和实践两方面分析了该原因及变形量的计算方法,为滑块加工过程中正确安装提供了理论调整数据,并给出了滑块加工中减少弯曲变形的方法,以提高工件折制精度.     

基于测试与仿真的数控折弯机滑块刚性分析

板料折弯机的滑块在折弯加工过程中会产生向上的弹性变形,导致折弯时模具之间压力分布不均匀,从而影响工件的折弯精度,因此滑块的刚性分析非常重要。运用应变电测技术与有限元仿真相结合的方法对某型号数控折弯机滑块的变形分别进行了实验测试和有限元计算,并将测试结果与计算结果进行比较,以验证有限元模型的正确性。在此基础上,将滑块高度与厚度作为设计变量,对滑块进行改进设计。改进设计结果表明:将滑块厚度增加20 mm、同时将高度增加100 mm时,滑块刚性得到了明显的提高。     

基于有限元技术的折弯机滑块分析与改进设计

滑块是数控板料折弯机的重要组成部分,对加工工件的精度有着重要影响。本文采用ANSYS有限元分析软件建立了折弯机整体有限元模型,对折弯机滑块进行了静力学分析,研究了滑块的应力分布与变形情况,研究发现液压缸活塞杆与滑块安装的方形开口周围应力过大。为提高该处结构强度,提出几种改进设计方案,通过有限元计算结果的比较,最终确定最合理的设计方案。     

折弯机液压补偿装置对工作台挠度曲线的影响分析与优化

折弯机的加工精度是最重要的性能指标之一。运用弹性力学理论对工作台变形进行分析,折弯时滑块与工作台共同受到板材的反作用力,必然会产生明显的挤压变形,从而导致上、下模发生相同的挠曲变形,严重降低了工件的折弯角度及直线度。以某型数控折弯机为研究对象,为了提高加工精度,利用液压原理对工作台挠度进行压力补偿,运用有限元分析与实验测试相结合的方式,多变量建模并仿真,研究了折弯机在满载自由折弯工况下的补偿效果,并确定了最佳的优化方案,运用有限元理论解决了实际生产问题。     

液压板料折弯机的滚轮导轨式同步机构

板料折弯机设计制造中的一个关键问题是滑块的同步精度,即如何保证滑块下平面与工作台面的平行度问题,也就是要求滑块无论在何位置,它的下平面上各点与工作台面之间的差值,符合精度标准0.16/1000。在中小型液压板料折弯机中,目前常用扭轴式同步机构、多连杆同步机构和滚轮导轨式同步机构来实现滑块的同步要求。下面就W67Y-40型液压板料折弯机的滚轮导轨式同步机构进行受力分析和强度核算。     

折弯机三大件多层分体结构设计研究

立柱、工作台和滑块是折弯机关键零件,其强度和刚性对机床精度影响至关重要。通过分析立柱、工作台和滑块的结构及受力状况,提出一种多层分体组合结构,代替整体焊接结构,降低单件外形和重量,达到便于加工、运输和安装的效果。通过实际使用验证得出多层分体结构是折弯机尤其是大吨位折弯机大件理想的结构方式。     

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.     

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.     

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.