【作者】 张海龙；

【导师】 张勤河；

【作者基本信息】 山东大学 ， 机械设计及理论， 2009， 硕士

【摘要】 H型钢是一种截面面积分配更加优化、强重比更加合理的断面型材,因其优良的力学特性在工、农业生产中有着广泛应用,在国民经济建设中的作用日益增强。为解决尺寸精度和力学性能的问题,扩大产品的品种规格,迫切需要对轧制过程的进行计算机仿真模拟,以期达到优化热轧工艺参数、控制产品质量的目的。本文选择中型热轧H型钢精轧过程的计算机模拟作为研究课题,利用热力耦合大变形理论对热轧过程中金属的变形、温度及其影响因素进行分析,同时分析轧后轧件的温度场变化及残余应力。为获取高温下材料热物理属性,使用Gleeble-1500型热模拟试验机对试件进行800-1000°C之间的热模拟试验,研究某特定变形量条件下变形温度、应变速率对材料本构曲线的影响,测定在不同应变速率条件下的本构关系曲线,并通过数据拟合得到实验材料的本构模型,获得本研究中数值模拟所需的基本参数。建立热轧中型H型钢精轧过程的三维有限元热力耦合模型,根据实际生产条件,设定初始条件和边界条件等参数,同时为避免轧制过程中轧件网格变形过大而影响计算精度,采用网格重构方法对此过程进行数值分析,保证了轧制模拟过程顺利实现。利用H型钢精轧三维有限元热力耦合模型分析后可以得到各个机架间轧件的应力场和温度场分布情况,根据有限元分析结果,研究轧件内部金属质点的纵向流动,分析轧件在轧制过程中变形情况与金属流动情况,对轧件进行宽展分析,为合理制定规程提供了有益参考。建立轧后轧件散热分析有限元模型,分析H型钢冷却的温度、残余应力,将计算得到的轧件温度和轧制过程中的轧制力与生产现场数据进行对比分析,验证了有限元模型的准确性。通过实验分析回归出计算轧机负荷、轧件温度等经验公式,并利用模型对精轧前的冲击进行了分析,研究成果对于建立型钢轧制过程尺寸精度预报系统、优化热轧轧制工艺参数、开发新规格产品等具有重要的实际意义和理论价值。更多还原

【Abstract】 H-beam is one kind of sectional steel with optimized area, reasonable ratio of weight to strength, and has widespread application in industry, agriculture as well as in the civil product because of its fine mechanics characteristic ,which has significant function in the national economy construction nowadays.In order to improve the size precision ,mechanics performance and expand product variety specification, it is of high importance for adoption of the computer simulation in rolling process to achieves the optimized hot rolling technique parameter.This research chooses the topic of computer simulation in medium hot H-beam finish rolling process, using thermal-mechanical coupling analysis and big distortion theory to study metal distortion of the hot rolling process. In order to obtain the material physical property under high temperature, the Gleeble-1500 thermal simulation testing machine was employed to carry on test sample between 800-1000°C, function among deformity condition ,the distortion temperature, the strain speed was specified. The material feature is expressed by a few of formulas as the constitutive model.The three-dimension model coupled thermo-mechanical of FEM is built to analyze the finish-rolling of middle-sized H-beam .The initial condition and boundary condition etc are set according to the actual working condition . for the oversized distorting, remeshing technique was carried on to guarantee the continuation of rolling simulation process. the rolled stress and the temperature distribution of blank would obtain through thermal-mechanical coupling analysis, metal flowing and deformation in rolling process was carried on, the analysis has provided the beneficial reference for the reasonable formulation regulations. It is conformed to the reflection of conservation and makes the simulation of FEM completely and exactly.The two-dimension FEM model of heat transfer and residual stress is built to analyzes temperature field after finish-rolling and residual stress during the cooling process of H-beam, The regularities of distribution in stress and temporary field of different step of rolling are obtained. The results of FEM simulation which are the temperature of piece is compared with the fact to prove that the model of FEM about rolling is apt.The rolling force formulas are built with experiment regression based on computation data, and rolling impact before finishing rolling was studied ,the research results give a references to the establishment section rolling process size precision forecast system, and make a significance to optimize rolling craft parameter and develop new specification product ,and which have the vital practical significance and the theory value.更多还原