Physical Simulation of Mold-Filling Processing of Thin-Walled Castings under Traveling Magnetic Field

Mold-filling process of thin-walled castings under the condition of traveling magnetic field has been studied by physical simulation method using gallium melt and fast speed photography. Flow morphology and its formation mechanism were obtained and discussed for thin-walled casting. The influences of magnetic field density on the filling ability, filling velocity and mold filling time have been studied. The differences in filling capability between gravity casting and casting under the traveling magnetic field have been compared. The results indicate that the mold filling ability of the gallium melt increases greatly under the condition of traveling magnetic field; the filling time is shortened from 18 s under gravity field to 3 s under the traveling magnetic field and average flow rate of the melt increases from 1.6 to 8.68 cm3/s; the change law of the cross-section morphology of the gallium melt during the mold filling is that at first, the cross-section area does not change, then it decreases gradually. When the front of the melt reaches the end of the mold cavity, the front melt will backfill the mold; the wider the width of mold cavity, the better the mold filling ability. The mold filling ability of gallium melt in mold with upper magnetic conductor is better than that without upper magnetic conductor.

Solidified structure of thin-walled titanium parts by vertical centrifugal casting

The solidified structure of the thin-walled and complicated Ti-6AI-4V castings produced by the vertical centrifugal casting process was studied in the present work. The results show that the wall thickness of the section is featured with homogeneously distributed fine equiaxial grains, compared with the microstructure of the thick-walled section. The grain size of the castings has a tendency to decrease gradually with the increasing of the centrifugal radius. The inter-lamellar space in thick-walled casting parts is bigger than that of the thin-walled parts, and the profile of inter-lamellar space is not susceptible to the centrifugal radius.

Die Casting Mold Design of the Thin-walled Aluminum Case by Computational Solidification Simulation

Recently, demand for the lightweight alloy in electric/electronic housings has been greatly increased. However, among the lightweight alloys, aluminum alloy thin-walled die casting is problematic because it is quite difficult to achieve sufficient fluidity and feedability to fill the thin cavity as the wall thickness becomes less than 1mm. Therefore, in this study, thin-walled die casting of aluminum （Al-Si-Cu alloy： ALDC 12） in size of notebook computer housing and thickness of 0.8 mm was investigated by solidification simulation （MAGMA soft） and actual casting experiment （Buhler Evolution B 53D）. Three different types of gating design, finger, tangential and split type with 6 vertical runners, were simulated and the results showed that sound thin-walled die casting was possible with tangential and split type gating design because those gates allowed aluminum melt to flow into the thin cavity uniformly and split type gating system was preferable gating design comparing to tangential type gating system at the point of view of soundness of casting and distortion generated after solidification. Also, the solidification simulation agreed well with the actual die-casting and the casting showed no casting defects and distortion.

Filling mode and regularity of vertical centrifugal casting process of titanium alloy in thin-walled cylinder cavity

The mold filling process of titanium alloy in a thin-walled cylinder cavity under vertical centrifugal casting process was studied by means of the hydraulic simulation experiments. Results show that the filling mode of the melt in the cylinder cavity varies with casting wall-thickness. When the casting wall-thickness is less than or equal to the thickness of the first layer during the filling process, the melts fill the cavity from the bottom to the top.When the casting wall-thickness is greater than the thickness of the first layer during the filling process, the melts first fill the largest radius parts of the cavity with a certain thickness of the first layer from the bottom to the top of the cavity, and then they fill the cavity from the larger radius part to the smaller radius part. The melt filling ability increases with the increment of the mold rotational speed and the pouring temperature. In another aspect, the melt filling ability rises with the decrement of the melt viscosity, and the melt with the better filling ability is prone to fill the cylinder cavity layer by layer.

Eliminating shrinkage defects and improving mechanical performance of large thin-walled ZL205A alloy castings by coupling travelling magnetic fields with sequential solidification

ZL205 A alloys with large thin-walled shape were continuously processed by coupling travelling magnetic fields(TMF)with sequential solidification,to eliminate the shrinkage defects and optimize the mechanical performance.Through experiments and simulations,the parameter optimization of TMF and the influence on feeding behavior,microstructure and properties were systematically studied.The results indicate that the magnetic force maximizes at the excitation current of 20 A and frequency of 200 Hz under the experimental conditions of this study,and increases from center to side-walls,which is more convenient to process thin-walled castings.TMF can break secondary dendritic arm and dendrites overlaps,widen feeding channels,prolong the feeding time,optimize the feeding paths,eliminate shrinkage defects and improve properties.Specifically,for as-cast state,TMF with excitation current of 20 A increases ultimate tensile strength,elongation and micro-hardness from 186 MPa,7.3%and 82.1 kg/mm^(2) to 221 MPa,11.7%and 100.5 kg/mm^(2),decreases porosity from 1.71%to 0.22%,and alters brittle fracture to ductile fracture.

Numerical simulation for mold-filling of thin-walled aluminum alloy castings in traveling magnetic field

The numerical simulation for mold-filling of thin-walled aluminum alloy castings in horizontal traveling magnetic field is performed. A force model of Al alloy melt in the traveling magnetic field is founded by analyzing traveling magnetic field carefully. Numerical model of Al alloy mold-filling is founded based on N-S equation, which was suitable for traveling magnetic field. By using acryl glass mold with indium as alloy melt, the experiment testified the filling state of alloy in traveling magnetic field. The results of numerical simulation indicate that the mold-filling ability of gallium melt increases continually with the increase of the input ampere turns.

Numerical simulation and optimization of shell mould casting process for leaf spring bracket

Although the shell mould casting process has a wide range of application in many fields,the prediction of casting defects is still a problem.In the present work,a typical leaf spring bracket casting of ZG310-570 was fabricated by shell mold casting.The finite element model and ProCAST software were utilized for simulating the filling and solidification processes of the casting;and the formation mechanism of the gas pore,and shrinkage porosity defects were analyzed.The results indicate that the gas pore and shrinkage porosity defects are formed due to air entrapment,insufficient feeding and non-sequential solidification.Subsequently,through changing the position of risers,adding a connecting channel between the risers,and setting blind risers at the U-shaped brackets,an optimized gating and feeding system was established to improve the quality of the casting.After optimization,the gas pore and shrinkage porosity defects of the leaf spring bracket casting are effectively eliminated.The experiment results with the optimized casting process are in good agreement with the numerical simulation,which verifies the validity of the finite element model in the shell mould casting.

Microstructure and mechanical properties of BFe10 cupronickel alloy tubes fabricated by a horizontal continuous casting with heating-cooling combined mold technology

A new horizontal continuous casting method with heating-cooling combined mold （HCCM） technology was explored for fabri- cating high-quality thin-wall cupronickel alloy tubes used for heat exchange pipes. The microstructure and mechanical properties of BFe 10 cupronickel alloy tubes fabricated by HCCM and traditional continuous casting （cooling mold casting） were comparatively investigated. The results show that the tube fabricated by HCCM has smooth internal and external surfaces without any defects, and its internal and external surface roughnesses are 0.64 μm and 0.85 μm, respectively. The tube could be used for subsequent cold processing without other treatments such as surface planning, milling and acid-washing. This indicates that HCCM can effectively reduce the process flow and improve the pro- duction efficiency of a BFel0 cupronickel alloy tube. The tube has columnar grains along its axial direction with a major casting texture of {012}〈 621 〉. Compared with cooling mold casting （6 = 36.5%）, HCCM can improve elongation （3 = 46.3%） by 10% with a slight loss of strength, which indicates that HCCM remarkably improves the cold extension performance of a BFe 10 cupronickel alloy tube.

Effect of depressurizing speed on mold filling behavior and entrainment of oxide film in vacuum suction casting of A356 alloy

The effect of depressurizing speed on mold filling behavior and entrainment of oxide film of A356 alloy was studied. Themold filling behavior and velocity fields were recorded by water simulation with particle image velocimetry. The results show thatthe gate velocity first increased dramatically, then changed with the depressurizing speed: the gate velocity increased slowly atrelatively high depressurizing speed; at reasonable depressurizing speed, the gate velocity kept unchanged; while at lowerdepressurizing speed, the gate velocity decreased firstly and then kept unchanged. High gate velocity results in melt falling backunder gravity at higher speed. The falling velocity is the main factor of oxide film entrainment in vacuum suction casting. The designcriterion of depressurizing rate was deduced, and the A356 alloy castings were poured to test the formula. The four-point bend testand Weibull probability plots were applied to assessing the fracture mechanisms of the as-cast A356 alloy. The results illuminate amethod on designing suitable depressurizing speed for mold filling in vacuum suction casting.

基于AnyCasting的电机支架离心铸造有限元仿真

为了获得力学性能优良的电机支架铸件,分析了其离心铸造成型原理。运用有限元软件AnyCasting建立了电机支架离心铸造成型仿真模型,对离心铸造成型过程中的钢液流动速度、温度随离心铸造时间的变化趋势进行了有限元仿真分析。对充型100%时铸件碳偏析分布进行了有限元分析。结果表明:在电机支架离心铸造成型过程中,铁液在自身重力及离心力作用下,由下往上不断充型;在不同离心铸造阶段,铁液流动速度及温度分布不同,且最大值主要分布在浇注口、壁厚较厚及实心部位。

基于ProCAST的镁合金惯组支架砂型铸造工艺研究

为实现镁合金惯组支架的高效率、高质量研制,使用ProCAST软件仿真优化ZM5镁合金惯组支架铸造工艺。通过对充型、凝固过程进行分析,发现铸件内部的3条薄壁筋板易出现浇不足、冷隔缺陷,圆弧面内侧厚壁筋条易出现缩孔、缩松等缺陷。经过优化设计,通过采取增加薄壁筋板厚度、调整内浇道位置、改变厚壁筋板上侧冒口结构等措施,较好地避免了上述铸造缺陷的产生,获得了合格的支架铸件。数值模拟仿真技术可应用于绝大多数航天构件的铸造过程分析,实现构件快速研制。

基于ProCAST的支架铸件熔模铸造工艺优化

分析了球墨铸铁支架铸件原工艺产生缩孔、缩松铸造缺陷的原因。通过ProCAST软件对工艺进行了分析和优化,对铸件浇注位置、排气位置等工艺参数进行了改进。结果表明:优化方案的铸件缩孔率总和为0.20%,缩松缩孔主要集中在直浇道和内浇道,并且缺陷明显减少。与原始方案相比,优化方案更合理。

基于Cast-Design的支架倾转铸造数值仿真

以某型旅游车装饰支架为对象,分析了其成型工艺。运用专业有限元铸造设计及仿真软件Cast-Design建立了支架倾转铸造成型数值仿真模型,对倾转铸造成型过程中的6063铝合金熔融液流动速度、温度分布及不同冷却速度下的屈服强度、抗拉强度进行了数值仿真。结果表明:随着支架倾转铸造成型的进行,流动速度及温度都逐渐减小,且在不同倾转铸造阶段其分布不同;随着冷却速度的增加,支架铸件的屈服强度和抗拉强度都呈现先增加后基本不变的趋势。

深厚软土且空间受限条件下桩板结构现浇梁支架方案设计

桩板结构具有结构简单、受力明确等优点,能够减少材料用量,降低工程造价,在跨越小面积的河流、道路或其他交通设施时,得到广泛使用。莲鹤大道项目与珠肇高铁并行段,设计采用桩板结构桥梁,共计3100m,地质条件复杂,淤泥质软土深厚,梁底距离地面空间受限,现浇梁施工难度大。设计方建议采用贝雷梁+工字钢结构形式支架方案,由于部分梁底距离地面净空不足,该方案向下反开挖最多达3.0m,施工工效低,投入大。本文针对不同净空条件,研究了三种支架结构,满足共线段3.1km桩板结构现浇梁施工,提高了施工工效,降低了施工成本,为后续类似工程提供了参考。

基于ProCAST的铝合金减速机支架消失模铸造工艺的模拟及优化

据所用的材料及结构特点,初步确定了铝合金减速器支架的铸造工艺。采用Pro/E软件对减速器支架及其浇注系统进行了三维造型。采用ProCAST软件对浇注过程进行了模拟分析,并根据模拟结果提出了改进的铸造工艺,即在铸件顶部增加2个半圆形冒口以及在铸件下部增加4个环形冷铁。结果显示,铝合金减速器支架中缩松等缺陷大幅度减少。

ProCAST模拟仿真技术在平衡肘支架铸造缺陷预测方面的应用

针对履带车体整体机械加工时,组焊件平衡肘支架在固定位置螺纹孔内出现铸造缺陷的问题,采用ProCAST模拟仿真技术对铸造工艺进行了模拟与优化,预测了该产品铸造缺陷的分布,降低了铸件的不良品率,提高了经济效益。

不锈钢支架熔模铸造工艺优化

通过ProCAST软件对除草机不锈钢支架进行熔模铸造的数值模拟,预测铸件缩孔缺陷分布情况,并对其浇注系统进行改善。利用正交试验对铸件的工艺参数进行研究,通过分析获得工艺参数的最佳方案。对该结果进行数值仿真以及实际铸造,发现铸件缺陷明显减少,这为不锈钢支架的生产提供了参考。

铰链支架压铸工艺设计和优化

根据铰链支架结构进行压铸工艺设计,针对其结构特点设计了两种压铸工艺,利用Anycasting分析软件对两种工艺进行数值模拟,对比分析两种工艺方案铸件缺陷产生的位置及原因,结合实际生产条件,选择了一种较优的压铸工艺进行优化,优化内浇道和溢流槽的数量和位置,改空冷和水冷。经模拟分析及试模证实优化措施有效,满足生产质量要求。

汽车发电机支架压铸模设计及成型工艺优化

针对汽车发电机支架结构特点及品质要求高等问题,运用PQ2图优化电机支架压铸模设计,应用UG、FLOW-3D软件进行有限元模型的建立、模拟分析,预测铸件内部出现气孔、缩孔缺陷问题,优化发电机支架压铸成型工艺。通过对模具设计及压铸工艺的优化,进行生产并对生产的发电机支架铸件进行X射线探伤检测及精加工。结果表明,通过PQ2图优化模具设计及FLOW-3D优化压铸成型工艺,有效预防了发电机支架压铸成型缺陷产生,提升了铸件品质的同时又缩短了产品开发生产周期。

SLM3D打印技术与失蜡铸造技术在可摘局部义齿支架制作中的应用

目的分析选择性激光熔融(SLM)3D打印技术与失蜡铸造技术在可摘局部义齿支架制作中的应用效果。方法选取2021年5月至2023年5月汉中市口腔医院收治的86例KennedyⅠ类牙列缺损患者作为研究对象,根据随机数表法将患者分为A组和B组各43例。A组采用SLM3D打印技术行可摘局部义齿支架制作,B组采用失蜡铸造技术行可摘局部义齿支架制作。两组患者于义齿佩戴1周后复诊,比较两组患者口腔内黏膜压痛点数量、义齿支架佩戴效果以及咀嚼效率;两组患者于义齿佩戴1个月后再次复诊,比较两组患者的满意度评分、主观感受评分及并发症发生情况。结果义齿佩戴1周后,A组患者口腔内黏膜平均压痛点为(0.61±0.13)个,明显少于B组的(2.23±0.21)个,A组患者吸光度值为0.61±0.05,明显高于B组患者的0.43±0.03,差异均有统计学意义(P<0.05);义齿佩戴1周后,A组患者的固位性、适合性和稳定性分别为55.81%、53.49%、58.14%,明显高于B组的30.23%、27.91%、32.56%,差异均有统计学意义(P<0.05);义齿佩戴1个月后,A组患者的主观感受评分和满意度评分分别为(28.07±2.75)分、(14.66±3.21)分,明显高于B组患者的(16.55±0.44)分、(6.68±1.32)分,差异均有统计学意义(P<0.05);义齿佩戴1个月后,A组患者的并发症总发生率为6.98%,明显低于B组患者的23.26%,差异有统计学意义(P<0.05)。结论SLM3D打印技术在可摘局部义齿支架制作中的应用效果良好,制作义齿支架较传统失蜡铸造技术偏差更小,具有更高的精确度,同时患者使用舒适度和满意度也更高,值得临床推广应用。