卧式离心复合铸造轧辊铸造过程及工艺影响的数值模拟

发布时间：2018-03-01 16:43

本文关键词： 复合轧辊卧式离心复合铸造温度场应力场铸造缺陷　出处：《燕山大学》2016年博士论文　论文类型：学位论文

【摘要】：离心复合铸造是一种能够生产双层或多层复合铸件的最简便方法,已广泛应用于复合轧辊、复合钢管的铸造。但在双层及多层复合铸造过程中,由于内外层材料的不同,如何保证各层材料良好结合的工艺控制成为关键问题。采用传统的试错法确定工艺成本高、浪费资源,研究开发专用软件又需要大量的基础工作,使其推广和应用受到很大限制。本文试图利用通用有限元商用Pro CAST软件,建立卧式离心复合铸造的有限元模型,为实现离心复合铸造过程的流场、温度场和应力场的模拟,优化离心铸造轧辊铸造工艺,提高轧辊质量,提供一种通用、简便的技术手段。离心铸造过程是复合轧辊生产关键工艺阶段,而商用的Pro CAST软件在模拟卧式离心铸造过程中存在严重的失真问题。为解决这一问题,本文提出根据金属质点的受力特点,将筒形件卧式离心铸造化分为符合重力流动规律的流道流动和接触旋转铸型后的离心流动两部分,分别建模的方法。用该方法对卧式离心铸造充型过程进行模型,并利用已有水力学试验对模型进行验证,结果表明该方法能够实现筒形件卧式离心流动的模拟。利用分段建模方法对典型筒形件(湿式汽缸套)卧式离心铸造过程的流场和温度场进行了模拟研究,模拟结果与实际工艺符合的较好,进一步验证了Pro CAST模型在卧式离心铸造流动充型和凝固过程模拟的正确性。通过模拟研究,分析了各种工艺参数对缺陷深度的影响,解决了卧式离心铸造湿式汽缸套铸造缺陷深度大、废品率高的问题。在卧式离心铸造模拟的基础上,提出了轧辊复合铸造过程模拟的Pro CAST模型。运用该模型模拟了Cr4轧辊复合铸造整个过程中的流场、温度场及外层模具的温度场,并实测了铸型对应位置的温度和Cr4轧辊相应位置的组织结构,对比模拟结果及实验结果,模拟结果与实验结果相一致。通过测定外层Cr4钢和中间层材料的力学性能,利用Pro CAST软件建立了轧辊复合铸造过程的应力场模型并进行了模拟,获得了轧辊复合铸造凝固过程的应力场和残余应力场。对比轧辊外层实测应力,模拟结果与实测结果具有相同的分布规律。分析了影响轧辊外层与中间层间界面结合质量因素,给出了中间层与外层能否实现冶金结合和结合层厚度最小的质量判据;研究了不同铸造工艺参数条件下能够保证全部结合的外层离心时间,以及各种参数对外层有效厚度的影响程度,给出了各因素影响外层有效厚度的主次顺序为:中间层浇铸温度内表面换热系数中间层厚度涂层厚度端盖砂材料。针对轧辊下轴颈存在缩孔的实际问题,研究了冷铁壁厚、材料、长度和下箱砂材料等因素对下轴颈中心缩孔位置及尺寸的影响,设计了合理的工艺技术,能够完全消除了下轴颈的中心缩孔。
[Abstract]:Centrifugal composite casting is the most convenient method to produce bilayer or multilayer composite castings. It has been widely used in the casting of compound rolls and steel pipes. However, in the process of bilayer and multilayer composite casting, due to the difference of inner and outer layer materials, How to ensure the process control of the good combination of different layers of materials becomes a key problem. The traditional method of trial and error is used to determine the high cost of the process and waste of resources. The research and development of special software also needs a lot of basic work. In this paper, the finite element model of horizontal centrifugal composite casting is established by using the general finite element commercial Pro CAST software. In order to simulate the flow field, temperature field and stress field of centrifugal composite casting process, this paper attempts to establish the finite element model of horizontal centrifugal composite casting. To optimize the casting process of centrifugal casting roll, to improve the quality of roll and to provide a general and simple technical means, the centrifugal casting process is the key process stage of compound roll production. However, the commercial Pro CAST software has serious distortion problem in the process of simulating horizontal centrifugal casting. In order to solve this problem, according to the stress characteristics of metal particles, The horizontal centrifugal casting of cylindrical parts is divided into two parts: the flow of flow channel following the law of gravity flow and the centrifugal flow after contact rotating casting. The modeling method is used to model the filling process of horizontal centrifugal casting. And the model is verified by the existing hydraulic tests. The results show that this method can simulate the horizontal centrifugal flow of cylindrical parts. The flow field and temperature field of typical cylindrical parts (wet cylinder sleeve) in horizontal centrifugal casting process are simulated by the method of segmental modeling. The simulation results are in good agreement with the actual process, which further verifies the correctness of the Pro CAST model in the flow filling and solidification process simulation of horizontal centrifugal casting. Through the simulation study, the influence of various process parameters on the defect depth is analyzed. The problems of high defect depth and high waste rate in horizontal centrifugal casting wet cylinder liner casting are solved. On the basis of horizontal centrifugal casting simulation, The Pro CAST model of roll compound casting process simulation is put forward. The flow field, temperature field and temperature field of outer die are simulated by using this model in the whole process of Cr4 roll compound casting. The temperature of the mould and the structure of the Cr4 roll are measured. The simulation results are in good agreement with the experimental results. The mechanical properties of the outer Cr4 steel and the interlayer material are measured. Using Pro CAST software, the stress field model of roll compound casting process is established and simulated. The stress field and residual stress field in the solidification process of roll compound casting are obtained. The simulation results have the same distribution law as the measured results. The factors affecting the interface bonding quality between the outer layer and the middle layer are analyzed, and the quality criterion of whether the metallurgical bonding and the minimum thickness of the bonding layer can be realized between the intermediate layer and the outer layer are given. The effect of different casting parameters on the effective thickness of the outer layer was studied. The primary and secondary order of the factors affecting the effective outer layer thickness is as follows: the heat transfer coefficient of the inner surface of the intermediate layer casting temperature; the thickness of the intermediate layer coating sand material; the thickness of the cold iron wall is studied in view of the practical problem of the shrinkage hole in the shaft neck under the roll. The influence of material length and bottom box sand material on the position and size of the central shrinkage hole of the lower axle neck is discussed. The reasonable technology is designed to eliminate the center shrinkage hole of the lower axle neck completely.
【学位授予单位】：燕山大学
【学位级别】：博士
【学位授予年份】：2016
【分类号】：TG249.4

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