基于凝固模拟的冒口高度设计及验证

采用铸造模拟分析软件对不同冒口高度的13500 kg钢锭的凝固过程进行了计算机模拟分析,并预测了钢锭的缩孔缺陷的分布。结果表明,原来生产过程中钢锭冒口高度下的缩孔深度较大。将模拟结果与试验结果进行对比后,两者吻合良好。在此基础上,用计算机模拟优化了冒口高度并进行试验验证。模拟与试验结果表明,优化后的冒口高度可以消除缩孔缺陷,因而提高了钢锭质量和利用率。     

冒口高度对大型锻造钢锭内部质量影响的数值模拟研究

通过数值模拟研究胃口高度对45 t钢锭凝固过程和内部质量的影响,通过钢锭生产和钢锭模测温验证了模拟结果的合理性.模拟结果表明,对大型上注钢锭,胃口高度越高,心部疏松越小,但对钢锭本身温度场分布和偏析形成影响不大,凝固条件主要受钢锭本身结构的影响.     

一种极简便的火柴压力冒口

我厂第二产品黄麻并条机握持板(材料牌号为ZQA19—4),这种牌号铜铸件收缩很大容易产生集中缩孔,而且由于铸件形状比较特殊(详见附图),薄处仅3毫米,厚处18毫米,热节园直径达30毫米。我们在热节处设置     

多向侧抽模具的设计一例

介绍了北京122型汽车左进气口外罩塑件在国产化过程中,模具设计中存在的困难及解决的办法,特别对抽芯不平衡、顶出偏心以及先复位机构的设计做了较详细的解释。     

多向锻造和时效处理对2014铝合金滑动磨损性能的影响

利用多向锻造和时效处理对2014铝合金进行了加工,研究了材料的微观组织、强度、硬度、塑性和滑动磨损性能。结果表明:晶粒细化导致材料具有较高的强度和硬度。多向锻造和时效处理后,较高的硬度以及磨损过程中较强的加工硬化大幅度增强了材料的抗滑动磨损性能。     

PPG发布两款ULTRAX新品的产品参数

<正>低温喷雾式清洁剂帮助工厂实现节能2010年3月8日,美国宾夕法尼亚州匹兹堡市——PPG工业公司(纽约证交所代码:PPG)工业涂料部公布了ULTRAXLTC10和ULTRAXLTC20两款清洁剂的产品参     

多向强应变和时效处理对Al-Zn-Mg-Cu合金摩擦磨损性能的影响

为探明多向强应变和时效处理对Al-Zn-Mg-Cu合金的显微组织、力学性能和摩擦磨损性能的影响,以多向锻造和时效处理工艺加工Al-Zn-Mg-Cu合金,对其显微组织进行了表征,并对其力学性能和摩擦磨损性能进行了测试。研究结果表明：经多向锻造加工后,Al-Zn-Mg-Cu合金的强度和硬度提高,但伸长率和耐磨性却大幅度下降。锻造合金再经120℃×1320 min时效处理后,强度和硬度进一步提高,伸长率得到明显改善,耐磨性增强。Al-Zn-Mg-Cu合金的抗拉强度、硬度和伸长率分别达到644 MPa、210 HV和14.9%,耐磨性较挤压T6态提高了68.3%。由于高的硬度和加工硬化使耐磨性增强,并且晶界析出相的不连续分布降低了晶界处的应力集中,从而也改善了Al-Zn-Mg-Cu合金的耐磨性。     

一种熔铸型炸药冒口自动去除装置的设计

描述了一套自动去除冒口装置的机构原理、功能实现及控制系统硬件和软件的设计方法。采用PLC和工控机两级控制结构,控制系统结构简洁、运行可靠并且调试方便。采用工业控制领域中广为应用的PROFIBUS现场总线构建分布式控制系统,实现对去冒口装置的远程控制。基于西门子公司的Win CC系统开发了上位机人机操作界面,为整个自动化控制系统提供了一款便于操作、性能可靠的智能软件。该装置实现了去冒口装置的自动控制,节省了大量的人力,提高了整个去冒口过程的安全性和自动化水平。     

侧暗冒口在拖拉机及发动机铸件上的应用——介绍一种补缩能力强的暗冒口

生产清洁而致密的铸件时,有效的浇注系统应完成以下任务:     

一种大型高效丸砂分离器的研制

介绍了大型高效丸砂分离器的结构、工作原理及主要结构参数。     

消除风电轴承座铸件夹渣缺陷的铸造技术研究

轴承座为大型风力发电机组的重要零部件之一,属较为典型的球墨铸铁铸件,其在铸造生产过程中极易出现夹渣缺陷。对其夹渣缺陷形成机理进行理论分析,通过优化设计和实践验证形成有效的避渣浇注系统方案,消除铸件高动载荷区和轴承安装配合面的夹渣缺陷。     

Research on the squeeze cast technology of the castings with large ratio of height to thickness

1 Introduction Squeeze cast is a near-net shape casting technology. In the squeeze cast process liquid metal fills and solidifie under high pressure, which enhances the castings' feeding and forming capacities effectively, and this significantly increases the inherent quality and appearance quality o the castings. It is important for us to study squeeze cas technology in order to save raw materials, decrease energy consumption and improve the quality of castings [1-4]. The squeeze cast process…     

Constitutive analysis and processing map for hot working of a Ni-Cu alloy

The hot deformation behavior of a Ni-Cu alloy was studied using hot compression testing in the temperature range of 950 °C–1150 °C and at strain rates of 0.001 s^?1-1 s^?1. Flow curves at low strain rates, up to 0.01 s^?1, were typical of DRX characterized by a single peak, while at higher strain rates, the typical form of a DRX flow curve was not observed. The power-law constitutive equation was used to correlate flow stress to strain rate and temperature, and the apparent activation energy of hot deformation was determined to be about 462.4 kJ/mol. The peak strain and stress were related to the Zener-Hollomon parameter and the modeling formula was proposed. The dependence of flow stress to the Z changed at ln Z=38.5, which was considered to be a critical condition for the change in the mechanism of dynamic recrystallization. The efficiency of power dissipation was determined to be between 10–35 percent at different deformation conditions. According to the dynamic material model, stable flow was predicted for the studied temperature and strain rate ranges. Highly serrated grain boundaries at low strain rates were considered to be a reason for the occurrence of continuous dynamic recrystallization. On the contrary, at high strain rates, equiaxed grain structure was attributed to the typical discontinuous dynamic recrystallization.     

The effect of processing parameters on the fatigue properties of D357 investment castings

Investment casting has emerged as one of the most direct and desirable routes from liquid metal to parts of amazing complexity. Metallurgical developments since the late 1980s have enabled the design and manufacture of components used in static- and dynamic-loaded components. Foundry-process parameters used for such applications have been traditionally optimized with respect to static properties and governing mechanisms and are fairly well understood. The goal of this study is to evaluate how the combinations of process parameters that result either in maximum yield strength or maximum ductility also affect the fatigue life of components. The influence of some casting and heat-treatment parameters affecting microstructure (e.g., dendritic arm spacing, silicon-eutectic structure, and precipitation of age-hardening phases) is assessed on both the static tensile properties and fatigue life. S. Kennerknecht earned his MBA at McGill University in 1986. He is currently vice president of technology at Cercast Group and general manager of Cercast. X. Dumant earned his M. Eng. in metallurgy at Ecole Centrale de Paris, France, in 1984. He is currently technical director at Ciral, France. R. Tombari earned his B. Eng. in metallurgy at McGill University in 1983. He is currently chief process engineer at Cercast, Canada. P. Van Biljon earned his M. Eng. in metallurgy at University of Witwatersrand, Johannesburg, South Africa in 1985. He is currently process engineer at Cercon, Texas.     

Preparation of a new animal glue binder for foundry use

A new casting binder was prepared based on an animal bone glue. In order to overcome the disadvantages of the animal glue agglomeration at room temperature, an alkaline decomposition process was used, with acrylic acid, ammonium persulfate, and glucose as modifiers of the animal glue to obtain a high strength of binding. In the process of alkaline decomposition, Na OH was used as the catalyst with the addition of 3, 4, 5, 6, 7, 8wt.%, respectively, into 100 g of animal glue and the alkaline decomposition temperature was set for 30, 40, 50, 60, and 70 °C, with an identical decomposition time of 30 min, in order to reduce viscosity of the animal glue and maintain a liquid state at room temperature. The added acrylic acid, ammonium persulfate and glucose were determined through an orthogonal experiment. The experimental results are as fol ows: the optimal amount of NaOH addition is 5wt.%; alkaline decomposition temperature is 50 °C; the optimal weight ratio of three kinds of modifiers to animal glue is acrylic acid : ammonium persulfate : glucose : animal glue = 30:3:15:100; the modification reaction should be performed at 75 °C with a reaction time of 90 min. With the addition of 3% binder to sand, a final tensile strength of about 3.36 MPa and surface tension value of about 25.387 m N·m~(-1) are achieved; the gas evolution at 850 °C is 19 ml·g~(-1) and the residual strength after high temperature(700 ■× 10 min) is 0 MPa. Finally, the new binder was characterized and analyzed by means of element analysis and an IR infrared spectrum.     

铸件有限元法数值仿真关键技术研究

铸件设计过程中,有限元数值仿真技术已获得了广泛应用.然而由于铸件必须用三维块体单元建模,当追求仿真精度时,通过增加单元数量加密有限元网格必将导致求解上的困难.针对这一难点,本文研究了铸件建模的关键技术:子结构法及子模型法,并用于车辆复杂铸件的强度设计.与实测相吻合的计算结果表明,这些技术对铸件数值仿真具有普遍指导意义.     

半椭球体薄壁铸件的差压铸造工艺优化

从半椭球体铸件的结构特点出发,结合差压铸造的特性,对其在铸造过程中可能出现的缩孔、缩松等铸造缺陷进行了分析,制定出合理的差压铸造工艺。针对清铲过程中出现的不足,对铸造工艺进行了优化,既方便了清铲,又提高了工艺出品率,最终生产出合格的铸件。     

3D processing map for hot working of extruded AZ80 magnesium alloy

The hot deformation behavior of extruded AZ80 magnesium alloy was investigated using compression tests in the temperature range of 250–400 °C and strain rate range of 0.001~(–1).000 s~(–1). The 3D power dissipation map was developed to evaluate the hot deformation mechanisms and determine the optimal processing parameters. Two domains of dynamic recrystallization were identified from the 3D power dissipation map, with one occurring in the temperature and strain rate range of 250–320 °C and 0.001–0.010 s~(–1)and the other one occurring in the temperature and strain rate range of 380–400 °C and 0.001–0.003 s~(–1). In order to delineate the regions of flow instability, Prasad's instability criterion, Murty's instability criterion and Gegel's stability criteria were employed to develop the 3D instability maps. Through microstructural examination, it is found that Prasad's and Murty's instability criteria are more effective than Gegel's stability criteria in predicting the flow instability regions for extruded AZ80 alloy. Further, the 3D processing maps were integrated into finite element simulation and the predictions of the simulation are in good agreement with the experimental results.     

Determining the optimal holding time at solutioning temperature from the structural characteristics of aluminum alloy castings

Metal Science and Heat Treatment -