压铸中冲头的慢速压射行程计算法新探

以往计算慢速压射行程都是从“慢速压射行程是从冲头起动运行至金属液充满压室和浇注系统为止的行程”这一观念出发的。其理由是:如果在冲头的快速压射阶段开始时,压室和浇注系统内还没有填满金属,那么,由于在快速压射阶段中,冲头以很大的速度运行,因而金属液的流动及其颤动,就会卷入压室和浇注系统中残余的气体;金属液和气体两相混流,一起进入型腔,从而造成铸件的气孔。但是,这只是矛盾中的主要     

DM3500压铸机企板优化设计

分析了压射机构刚度设计不合理,导致DM3500压铸机压射冲头快速磨损的原因。基于SIMP变密度拓扑优化算法开展压射机构企板的优化设计,首先建立了压射机构的力学模型,通过有限元法计算多个工况下压射机构的刚度,进而建立优化设计模型,进行拓扑优化。根据单元密度云图结果建立了企板优化方案模型,将优化方案与原始设计进行对比分析。结果表明,优化设计后的压射机构刚度较优化前提升35.6%,可以有效抑制冲头快速磨损,同时实现企板轻量化,减重率为3.4%。     

压室表面品质对压铸充型补缩过程的影响

以某铝合金气缸盖压铸件为例,通过对其品质异常时间段内的补缩相关过程参数进行排查分析,阐述了压射室质量状态对其品质的影响。结果表明,压射室内腔粘铝将显著降低保压过程冲头对压力的传递,导致浇道对热节位置的补缩效果减弱后出现缩松缺陷。全自动生产设备实时监控系统有助于反馈设备的运行情况,但还不能准确反馈冲头运行时所受的阻力变化对压射及保压过程的影响,因此压射室表面品质的精细化管理非常重要。     

液态金属在冷室压铸机压室中运动的理论与分析

应用流体力学原理对液态金属在卧式冷室压铸机压室中的运动进行了理论分析和计算,阐明了冲头匀速运动和匀加速运动情况下波的运动情况和计算公式。据此分析认为:卧式冷室压铸机冲头的慢压射过程是加速运动和匀速运动的组合,组合的结果直接影响压铸件的质量。液态金属在压室卷入的空气量,与慢压射加速度、慢压射速度、起始充满度、压室直径有关,并存在一个临界慢压射速度和最佳加速度,在此速度和加速度下可使卷入的空气量最小,铸件气孔率最小。     

冷室卧式压铸机压射装置

资料来源:中国发明专利公报;公开号:CN1042322A;公开日期:1990年5月23日;申请人:上海电器压铸厂一种金属压铸设备使用的压射装置,包括一个开有喂料通孔的压射室9和一个可在压射室中滑动和转动的压射冲头10。冲头前部沿轴向开有上、下各一条辅助进料槽及均压槽,它们各与压射室内壁限定一辅助流道和均压流     

一种双冲头压射机构

壁厚不均匀的压铸件,厚壁处容易产生缩孔:薄壁处难以成形。为此,作者设计了一种采用双冲头能满足两者要求的压射机构。保留了一般压射机构中的增压器,并且采用较高的压射速度,促使铸件的薄壁部分成形。现分别介绍如下: 一、压射机构的改进改进后的压射机构如图1所示。当按下“压射”按钮后,压射阀17动作,高压油经阀11及10进入压射缸内,推动外压射活塞5进行第一级压射(压射速度应适应)。在冲头未封住浇料口之前,合模力已由独立的增压系统增压到预定的合模吨位。当冲头封住浇     

压室液态金属流动耦合温度场三维数值模拟

压铸过程中,压室内液态金属卷入的气体是影响铸件质量的原因之一.针对压室压射过程,引入冲头的移动规律以及流动过程中热量传递的计算,实现并开发了压室压射过程的流场耦合温度场的数值模拟程序.采用所开发的模拟程序对压室金属流动及传热过程进行了模拟,模拟结果与FLOW-3D的计算结果以及临界速度理论作比较,两者均吻合.采用压室模拟能够优化冲头的运动规律,使卷气最小.     

压室液态金属流动耦合温度场三维数值模拟

压铸过程中,压室内液态金属卷入的气体是影响铸件质量的原因之一.针对压室压射过程,引入冲头的移动规律以及流动过程中热量传递的计算,实现并开发了压室压射过程的流场耦合温度场的数值模拟程序.采用所开发的模拟程序对压室金属流动及传热过程进行了模拟,模拟结果与FLOW-3D的计算结果以及临界速度理论作比较,两者均吻合.采用压室模拟能够优化冲头的运动规律,使卷气最小.     

ALLPER压射冲头系统和TIOCCO过滤系统

1 九十年代的压射冲头系统 瑞士ALLPER公司生产一种专利冲头系统,由冲头杆、硬化的高导热ALLPER铜合金及可活动的冲头环组成。冲头环可自动调整与压室内壁保持密合,控制冲头与压室内壁之间的空隙。 这种冲头系统开有冷却水道,能很快将冲头热量带走,压室末端至注液口间设有润滑油槽,由一活塞泵控制油量,对冲头进行润滑。     

挤压铸造机压射系统的动态配合数值模拟

冲头和压室在挤压铸造过程中受热、荷载等因素影响产生变形。基于铸造模拟软件ProCAST建立数值模型,对阶梯薄板零件的挤压铸造立式压射过程进行了模拟,得到在8个挤压铸造周期中冲头和压室各自的变形量,计算出二者之间的动态配合间隙。结果表明,冲头和压室受热后径向尺寸都有所增大,且冲头的膨胀量大于压室的膨胀量,二者之间的间隙值由起始的0.1200mm减小到0.0298mm,且减小幅度逐渐变小,间隙值最终趋于稳定。     

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.