基于实例的典型汽车覆盖件模具设计

在分析了汽车发动机舱盖结构和工艺特点的基础上,确定了零件的冲压工序过程图,并对拉深、修边和翻边工艺性进行了阐述.同时,介绍了汽车覆盖件模具结构设计特点,并以CATIA为计算机辅助设计工具,设计出发动机舱盖拉深、修边及翻边成形所需的模具零件并对模具零部件进行装配,得到模具的装配体的三维数模.指出设计汽车覆盖件模具需要注意...     

旋转斜楔机构在汽车侧围外板翻边模中的应用

分析了汽车侧围外板的冲压成形工艺,提出了一种新的斜楔机构———旋转斜楔机构。将双向运动斜楔与旋转斜楔进行了对比,在侧围板外覆盖件翻边模具中采用旋转斜楔成形机构,大大提高了生产效率。     

汽车内板件一步翻边成形模具设计北大核心CSCD

为了提高生产效率、降低成本、减少生产准备时间,在分析了汽车内板件工艺特点的基础上,采用一步翻边成形工艺对板料进行冲压加工。以CATIA为计算机辅助设计工具,设计出汽车内板件翻边成形所需的模具零件,装配后得到模具装配体的三维数模。同时,介绍了汽车内板件模具工作零件的结构设计特点,即翻边上模采用镶拼结构,内部为压料兼做成形上模,下模分为固定凸模和活动顶起凸模两部分。坯料采用工艺孔定位模具的导向;上、下模之间的导向采用导柱导套形式;上模本体与压料块之间的导向采用导滑块与滑配面的形式;下模本体与凸模镶块之间的导向采用导柱导套形式。实践证明,所设计的模具工艺性良好、结构合理、符合生产要求。     

刃入时序对翻边回弹的影响及原因分析

翻边回弹一直是汽车覆盖件冲压成形中难以解决的成形缺陷,本文运用Auto Form软件模拟了多料翻边和少料翻边不同刃入时序的回弹,通过分析回弹量和应力状态,获得了不同刃入时序下翻边回弹的规律,为控制汽车覆盖件的翻边回弹提供了依据。     

汽车侧围成形工艺分析(连载二)

汽车覆盖件中,侧围是最大的,其负角翻边多,成形难度大。介绍了汽车侧围的成形工艺,分析了各工序的关键部分,确定冲压工艺中型面的补充方向和工序数,以满足侧围的自动化生产要求。     

汽车侧围成形工艺分析(连载一)

汽车覆盖件中,侧围是最大的,其负角翻边多,成形难度大。介绍了汽车侧围的成形工艺,分析了各工序的关键部分,确定冲压工艺中型面的补充方向和工序数,以满足侧围的自动化生产要求。     

汽车覆盖件修边毛刺产生的原因及解决方案

阐述了汽车覆盖件修边毛刺产生的原因和具体解决方案,以材料成形、材料力学、冲压工艺工程等原理为基础,通过归纳总结实际生产中出现的汽车覆盖件修边毛刺问题,制定出汽车覆盖件修边毛刺在工艺设计、结构设计、数控加工、钳工装配4个方面的解决方案,有效提高了模具企业的生产效率,提升了产品质量。     

整体式车门外板窗框回弹控制

针对带有翻边的汽车外覆盖件在冲压成形过程中出现的回弹问题,现以某车门外板为例,从冲压工艺方案、A级曲面重新补偿、模具结构等方面进行阐述,应用CAE全工序模拟分析技术进行方案虚拟验证,控制成形制件的回弹,并将验证方案在结构设计中实施,同时结合A级曲面补偿,重构加工数模用于现场加工。通过现场生产验证该方法的有效性,表明该方法可以有效控制汽车外覆盖件因翻边导致的回弹。     

汽车覆盖件冲压工艺分析系统

研究开发了基于知识的汽车覆盖件冲压工艺分析系统。设计了系统总体架构及流程,提出了基于离散与合并思想的工艺分析方法,设计了几何特征自适应离散方法,以及相应的孔冲压方向和修边工艺分析算法。根据合并思想提出了工艺特征合并算法,能够对孔间及孔与修边提出合并方案。以特征为核心单元,分析计算特征的工艺参数,模拟特征的空间加工轨迹,并采用基于简化工具体的干涉检查方法实现汽车覆盖件冲压工艺设计与排布。通过对某发动机前盖内板的实例分析,验证了系统方案的有效性和实用性,系统能够快速完整地解决汽车覆盖件冲压工艺分析与排布问题。     

带气动切换机构的汽车顶盖翻边整形模设计

通过对汽车覆盖件的冲压工艺方案分析,介绍了一种带气动切换机构的汽车顶盖外板的冲压工艺方案,以及汽车顶盖的翻边整形模结构设计;实现了有天窗型顶盖和无天窗型顶盖外板的翻边整形工艺可以在同一副模具上进行生产的目的;重点讲述了顶盖翻边整形模结构、切换机构及工作原理。实际生产表明,该结构可降低模具开发成本,缩短模具切换时间,提高生产效率。     

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。     

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.