基于消失模铸造法的顶注式浇注铸件生产工艺

在金属铸造的工艺设计中,"优先顶注"是多数金属铸件所遵循的铸造原则,其中薄壁的中小型铸件通常采用顶注式浇注工艺。然而,顶注式工艺也存在很多缺陷和局限性,如对铸型底部冲击力大、金属液激溅氧化、对壁厚大于20mm的铸件易产生气孔砂眼夹渣等。针对顶注式工艺的局限性和缺点,本文提出了基于消失模铸造法的顶注式工艺。利用消失模铸造的诸多技术优点,弥补顶注法的不足。采用计算机模拟技术对顶注式消失模铸造法建立数理模型,模拟充型过程中的界面推移及温度分布状态,表明浇铸方案的有效性。     

基于铸造软件的发动机外壳件铸造过程的模拟

铸造铝合金在汽车、摩托车零件中广泛应用,但传统铸造方法铸造时间长,铸造缺陷多,已无法满足产品质量的稳定要求。半固态铸造作为一种新型铸造工艺,已逐渐得到行业和企业的重视。本文以铸造CAE软件的数值模拟方法作为研究手段,对摩托车发动机外壳件进行半固态铸造成形过程的有限元模拟。通过FLOW-3D铸造软件在液态和半固态情况下的模拟仿真,得到不同条件下的充型和浆料流动特点,获取合理的模拟凝固时间和保压时间。通过对比分析,得出相对优化的数值参数,为铸造企业进行相关的半固态铸造实验提供可参考的工艺参数。     

基于数值模拟的铝合金电机机盖高压铸造

基于数值模拟仿真了铝合金电机机盖高压铸造充型过程,分析了浇注温度对铸件充型完成时刻的温度场、卷气含量和表面氧化程度的影响,得出铝合金电机机盖高压铸造最合理的浇注温度为983K。实验结果表明,铸件充型完整,轮廓清晰,表面无冷隔、氧化,初生α-Al相组织最细最均匀,密度、抗拉强度和断后延伸率都达到最大值,实验结果同仿真结果吻合较好。     

铸造专业课程设计改革

为了提高学生分析和解决铸造工程实际问题的能力,在铸造专业课程设计中增加了铸件充型过程流场模拟、凝固过程温度场模拟。改革实践表明,在课程设计中引入数值模拟,提高了学生的学习兴趣和积极性,增强了学生的分析问题、解决问题能力和创新精神,使学生更加适应现代铸造生产的要求。     

基于数值模拟及3D打印的铁路货车闸瓦托工艺技术研究

在传统熔模铸造的基础上,开展了基于ProCAST及3D打印技术的快速铸造技术研究.以ProCAST为数值模拟平台,对闸瓦托充型、凝固过程的流场、温度场进行了模拟,选出最优方案;利用3D打印技术,完成了闸瓦托3D模型打印,消除了模具制造环节.结果表明,数值模拟技术、3D打印技术与传统的熔模铸造技术相结合,可将铸件试制周期缩短三分之一以上,并有效提高产品经济效益.     

AM60镁合金方向盘骨架压铸充型过程数值模拟

利用仿真软件FLOW-3D,对镁合金汽车方向盘骨架进行模拟.使用正交实验分析方法确定了压射速度、模具温度、浇注温度改变时压铸件产生缺陷百分比的变化.进行多组正交试验后,在优化的工艺参数下,观察液态镁合金充型及凝固过程中流场和温度场的分布情况,预测缺陷出现的部位,以寻求最佳的工艺参数,从而使铸造工艺和模具的设计得到了优化.模拟结果表明:最优的压射速度应为2.34m/s,模具初温为220℃,浇注温度为700℃,能达到最佳充型效果.     

浅析低压铸造成型技术在铜合金层面的应用

低压铸造成型技术既属于重力铸造法,又属于压力铸造法,是介于两者间的新型铸造法。它借鉴压力铸造法中的压力结晶凝固操作与重力铸造法的底注平稳充型操作,确保了合金在低压情况下铸造也能成型。然而,由于其倾向于铸造小型铸件,普及范围相对有限,在未来发展中,低压铸造成型技术应往大型化、精细化方向发展。     

CAE数值模拟在铸钢车轮件铸造中的应用

应用华铸CAE铸造工艺分析软件对铸件凝固过程进行数值模拟,通过计算机直接观察其充型与凝固过程,预测铸造缺陷的部位及其大小,根据缺陷优化调整工艺,制定出最佳工艺方案,生产出合格的铸件。     

铝板坯充型过程流场与温度场的耦合数值模拟

利用FLOW-3D软件对铝的充型过程进行了数值模拟,采用了耦合模拟的方法对结晶器内的流场和温度场进行了分析.通过比较不同的换热系数和浇铸速度下的结果,得到换热系数和浇铸速度对结晶器内流场和温度场的影响.     

铸造模拟对几种典型铸件的工艺改进

利用Anycasting分析软件对铸造行业中几种典型铸件进行充型凝固耦合分析,通过实践经验证明了铸造模拟仿真技术在铸造过程中对工艺方案的改进及成本的降低所起的积极作用。     

Simplified Discrete-Event Simulation Approach for Construction Simulation

The methodology of discrete-event simulation provides a promising alternative solution to designing and analyzing dynamic, complicated, and interactive construction systems. In this paper, an attempt is made to extend the previous work of simplifying construction simulation by delving into the fundamental approaches for discrete-event simulation. A new simplified discrete-event simulation approach (SDESA) is presented through extracting the constructive features from the existing event/activity-based simulation methods; both the algorithm and the model structure of simulation are streamlined such that simulating construction systems is made as easy as applying the critical path method (CPM). Two applications based on real road construction projects in Hong Kong serve as case studies to illustrate the methodology of simulation modeling with SDESA and reveal the simplicity and effectiveness of SDESA in modeling complex construction systems and achieving the preset objectives of such modeling. They are a granular base-course construction system featuring both cyclic and linear processes and an asphalt paving construction system with complicated technological/logical constraints. As a general-purpose method for construction planning, SDESA enables practitioners to deal with what the CPM-based network analysis method fails to solve by offering discrete-event simulation capabilities. Furthermore, the SDESA can potentially be adapted to special-purpose simulation tools to tackle large and complicated construction systems of practical size that have yet to find convenient solutions with existing simulation methods.     

中间包自由表面的数值模拟与物理模拟

应用计算机数值模拟研究了坝高、堰深、坝堰间距以及液面高度对中间包自由表面的影响,并通过水力学模拟验证数值计算结果的正确性。实验证明,计算机模拟的结果与水模实验结果基本相符,说明计算机模拟结果可以满足工程的需要。为优化设计中间包、减少卷渣的发生提供了有利的依据。     

δ′（Al3Li）相分离过程的计算机模拟研究

利用微观扩散方程对铝锂合金中δ′（Al3Li）的相分离过程进行计算机模拟。对于锂含量为15％（原子数分数）的合金，无序固溶体首先进行协调有序化，形成被反相畴界分割的单相有序畴；而后该有序相关进行匀相失稳分解，贫锂区自发无序化，最终形成平衡两丰状态。单相有序相分解主要发生在反相畴界处，使得反相畴界被有序－无序相界取代；分解过程中锂原子浓度从有序畴边缘开始增加，然后向中心过渡，不规则的两相界面逐渐变得平滑。     

感应加热中的温度场模拟

为克服钢铁材料在感应加热过程中温度难测量的难点,实现温度自动化控制.本文用有限元方法对感应加热过程中的温度场进行模拟.结果发现,模拟结果与实际加温过程相符,能很好的反应加热过程温度场的变化情况,为实际操作提供了有利依据.     

Simulation of continuous rolling

A mathematical model of a multicell continuous mill permits calculation of the strip dimensions on leaving the finishing cells. These dimensions depend on the kinematic mismatch in the intervals between the cells. The stress in these intervals is taken into account in the calculations. This model, which includes the relevant technological factors, is intended for computer simulation of continuous rolling.     

The Use of Simulation in Laboratory Scale in the Field of Process Simulation

For development and optimisation of steel grades or of steel production processes information about the evolution of steel microstructure during the production process is required. For this investigation a lot of steel samples of different production stages are necessary. Taking these samples in situ, however, needs great expenses. In order to reduce the cost, simulation in the laboratory scale is to be used. Here, the representative microstructures of steel can be produced and analysed comparatively easily. This paper gives an example to show the use of the laboratory simulation for fitting a computer model for Ti‐Nb‐carbonitride precipitation kinetics. It is also shown in this report which enormous effort is necessary to get information when the objects of investigation are such extremely fine particles. If a TEM is used, with particles below 10 nm the resolution range of the device is reached. Other methods, like chemical isolation, fail. The only chance is, as demonstrated here, to use the qualitative and semi‐quantitative results from the TEM investigation. This is a successful strategy for the development of a precipitation kinetics model for very fine particles.