基于正交试验的座椅撑板冲压成形回弹研究及优化

以某汽车座椅撑板为研究对象,采用Autoform有限元软件建立拉延过程有限元模型,对其成形和回弹进行分析。针对拉延成形过程中回弹量过大的缺陷,设计正交试验,选取压边力、摩擦系数、冲压速度和凸凹模间隙4个重要工艺参数作为因素,研究工艺参数对回弹量的影响规律,得到最优的工艺参数组合为:压边力250 k N,摩擦系数0.08,凸凹模间隙1.2 mm,冲压速度4000 mm·s~(-1)。采用优化参数组合进行试模,试验结果与数值模拟结果吻合较好,工件成形效果完全符合设计要求。     

基于DYNAFORM的汽车前防撞梁支撑板的拉延模具设计

汽车覆盖件是以冲压件为主的零件,而作为生产冲压件的冲压模具的设计,与汽车覆盖件的成形质量息息相关。利用DYNAFORM仿真软件对某汽车防撞梁支撑板进行了拉延仿真,并依据仿真结果对其冲压速度、拉延筋布置方案、压边力、凸凹模间隙等参数进行选取和设计。通过分析厚度变化云图,采用厚度差来评价成形结果,确定了具有较好成形效果的参数组合。仿真结果表明:在确定了拉延模具采用等效实体拉延筋的设置后,压边力为360 k N、冲压速度为4000 mm·s-1、凸凹模间隙为0.66 mm时,可获得最好的成形效果。本设计及其仿真结果为其他类型的汽车防撞梁支撑板拉延模具设计提供了有效参考。     

基于Autoform的汽车天窗加强环成形模拟及工艺优化

以某型号汽车天窗加强环为研究对象,通过对其结构进行分析,初步设计冲压工艺为拉延→修边、冲孔→修边、冲孔→翻边,初选压边力、摩擦系数、拉延筋阻力系数、工艺补充等参数,并利用Autoform进行数值模拟。根据模拟结果中所出现的起皱、减薄、开裂等缺陷,并结合产品结构,调整压边力、摩擦系数以及拉延工艺以得到符合实际生产的工艺参数、冲压工艺。最终确定的工艺参数为:压边力为2400 kN、凸凹模间隙为1.2 mm、摩擦系数为0.15;冲压工艺为:拉延→修边、冲孔→修边、冲孔→翻遍、整形→冲孔。根据确定的工艺参数进行成形实验,得到了合格的零件,有效地降低了模具的设计成本。     

汽车座椅外侧板单动拉延成形工艺分析及优化

以某型号汽车座椅外侧板为例,采用Auto Form软件对座椅外侧板拉延成形过程进行模拟分析,并根据分析结果预测出拉延过程中的拉裂风险。通过调整零件的圆角半径和修改局部结构,消除了开裂风险,降低了最大减薄率。为取得更好的成形效果,选取压边力、摩擦系数、冲压速度、凸凹模间隙4个重要成形工艺参数进行正交试验及参数优化,得出最优工艺方案为:压边力250 k N、摩擦系数0.13、冲压速度1000 mm·s-1和凸凹模间隙2.42 mm,最终零件的最大减薄率为24.33%,最大增厚率为6.54%。采用优化后方案进行实际拉深试模,得出零件的成形性能与有限元模拟结果一致,工件质量完全符合设计要求。     

基于Dynaform的铝合金汽车地板梁成形分析及工艺参数优化

为实现汽车的轻量化,对某轿车的铝合金地板梁的拉延成形进行研究,运用Dynaform软件对其成形过程进行模拟分析,研究了压边力F、摩擦系数f、冲压速度v及凸凹模间隙c对地板梁成形的影响规律。对上述4个工艺参数进行了正交优化,获得了最优的工艺参数组合:压边力1200 k N,摩擦系数0. 12,冲压速度2000 mm·s-1,模具间隙2. 835 mm。最终制件的成形效果良好,最大减薄率为21. 01%,最大增厚率为6. 25%。在模拟分析及正交优化的基础上对制件进行了实际的拉延试验,实际拉延制件的最大减薄率与最大增厚率与模拟结果的误差分别为2. 4%、6. 2%,均符合制件的质量评价标准。     

汽车顶盖前横梁拉延成形工艺数值模拟分析

汽车顶盖前横梁零件的拉延成形容易出现大面积成形不足、局部起皱和破裂。采用有限元分析软件Dynaform对零件拉延成形进行数值模拟,研究该零件拉延成形不足、起皱和破裂的原因及解决措施。研究结果表明,合理的拉延筋设置和压边力调整可以解决零件拉延成形不足、起皱和破裂的问题;汽车顶盖前横梁的拉延成形最佳模具设计参数及成形参数组合为:压边力1000 k N,并需设置半圆形拉延筋,摩擦系数取0.13,凸凹模间隙取0.88。最后通过生产实际结果验证了模拟参数组合的可行性。     

发动机罩外板拉深回弹的数值模拟分析

发动机罩外板结构简单,表面平直,曲率半径大,整体高度低。如果对外板拉深成形时的毛坯形状与尺寸、冲压方向与速度、拉延筋布局与结构以及压边力大小、凸凹模间隙、摩擦润滑等工艺因素的选择或控制不当,则容易导致其卸载后的回弹量增大。文章以eta/DYNAFORM软件为计算平台,利用正交实验法,对某轿车发动机罩外板的拉深回弹现象进行了数值分析,并在此基础上确定了控制回弹的拉深工艺参数和模具结构参数。实验结果表明,该外板零件的拉深回弹呈扭曲倾向,即存在一部分区域上翘,而另一部分区域下陷,其中下陷趋势较上翘明显。根据数值模拟分析得到满足外板技术要求的最优拉深工艺参数和模具结构参数组合为:压边力900kN,虚拟冲压速度1000mm/s(相当于实际冲压速度的10倍),拉延筋高度6mm,凸凹模间隙0.8mm。     

双相不锈钢大型封头成形多目标优化设计

基于正交试验法应用有限元数值模拟对双相不锈钢大型封头成形的工艺参数进行了系统性的多目标优化研究,利用直观分析法和排队评分法获取了凸凹模间隙、凹模入口圆角半径、拉延筋高度、拉延筋形状、拉延筋位置对成形质量、减薄率、回弹量的影响主次,得到了最优工艺参数组合,并对优化结果进行了生产验证。结果表明:采用凸凹模间隙11 mm,凹模入口圆角半径40 mm,位置在中间高度为20 mm的矩形拉延筋得到的封头无起皱、鼓包等成形缺陷,且封头最小壁厚为9.33 mm,最大壁厚为11.19 mm,回弹量较小。生产实际与模拟结果基本一致。采用该组工艺参数能提高双相不锈钢封头的成形质量。     

基于响应面法的汽车后轮罩工艺参数优化

以某汽车后轮罩作为研究对象,采用响应面法对冲压工艺参数进行优化。选取压边力、拉延筋阻力系数、摩擦因数、凸凹模间隙为工艺参数变量,优化目标为拉延工序最大减薄率和修边工序后最大回弹量。采用Box-Behnken法设计响应曲面试验,建立工艺参数与拉延工序最大减薄率和修边工序后最大回弹量之间的响应面模型;通过响应面模型优化得到的压边力为350 kN、拉延筋阻力系数为0.40、摩擦因数为0.13、凸凹模间隙为0.6 mm。采用经过优化的参数组合模拟得到的拉延工序最大减薄率和修边工序后最大回弹量的误差分别为0.5%和0.2%,可用于替代有限元模型进行计算。根据最优工艺参数组合指导模面回弹补偿并进行试生产,可以生产出满足质量要求的汽车后轮罩。     

基于正交试验和灰色系统理论的拼焊板前纵梁成形优化

影响拼焊板冲压成形的工艺参数较多,难以精确建立工艺参数与成形质量之间的关系。以压边力、拉延筋高度、凸筋圆角半径、凹筋圆角半径为自变量,进行四因素四水平正交试验,模拟拼焊板前纵梁拉延成形过程,获得最大减薄率和最大焊缝移动量的数据。利用灰色系统理论,分别计算成形工艺参数对单目标函数的关联系数和多目标函数的关联度,将多目标转换为以关联度为目标的单目标。进一步计算各成形工艺参数的平均关联度,将优化的压边力、拉延筋截面几何参数进行有限元模拟验证,指导设计、试模,成形的质量得到明显提高。     

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.