热态锻件锻造过程中尺寸与温度的关系研究

发布时间：2018-06-09 11:10

本文选题：热态锻件的尺寸 + 温度场函数　；参考：《燕山大学》2015年硕士论文

【摘要】：大型锻件是现代工业设备的核心部件,而大型锻件的生产工艺和锻造水平是国家制造力的重要标志之一。在高温条件下,大型锻件的制造生产工艺十分复杂,并十分耗费能源和材料,且造价极大。因此,大型锻件的质量保证和锻造工艺的改善对提高制造生产力和国民经济效益有着十分重要的意义。在大型锻件的热态成形过程中,锻造工艺优化的重要理论依据来源于锻件尺寸、温度、高径比,压下量等工艺参数的研究。在众多的锻造工艺参数中,锻件尺寸和温度是可以通过现代先进测量手段直接实时获取的,这为进一步研究锻件尺寸和温度的变化规律以及两者之间的相互关系打下了基础。实时地掌握锻件尺寸和温度的变化规律以及两者之间的相互关系,可以及时有效地调整锻造工序,从而可以很大程度地提高锻件的内部质量和锻造精度,进而为优化锻造工艺提供可靠的理论依据。因此,本文基于锻造过程中实时测量的锻件尺寸和温度,以构建锻件尺寸和温度之间的相互影响关系模型。首先,基于锻造过程中锻件的热传导理论和热源理论,对热态锻件尺寸变化影响下的温度场进行分析,并将锻件温度场分解为温降和温升时的两个温度场函数进行研究。结合锻造过程中锻件尺寸和温度的测量信息,以修正锻件尺寸变化时的传热系数计算公式,并利用二维非稳态传热模型来求取温降时的锻件温度场函数。基于能量守恒原理,构建锻件尺寸变化时的功能关系函数,并进一步改进其功能转换系数。结合锻件功能关系函数,利用可移动坐标系下的虚拟热源法求得锻件温升时的温度场函数。通过叠加温降和温升时的锻件温度场函数,以构建锻件尺寸变化时的温度场模型。其次,基于热态锻件内部成形质量参数的变化过程以及内部应力变化的特性,从不同的角度对锻件温度对锻件尺寸变化的影响关系进行分析,并利用多元函数微分法以求取锻件尺寸变化和应力之间的关系函数。结合锻件形变时的能量函数和尺寸应变公式,对锻件能量形变参数进行分析和求解,以获取锻件温度与应力之间的关系函数,并以锻件应力为中介变量来构建锻造过程中锻件温度影响下的尺寸变化模型。最后,结合上述所建立的锻件温度和尺寸变化模型,利用实验室和锻压现场条件构建锻造模拟实验,以获取的锻件测量信息和实验结果。并利用Deform-3D软件对锻件的锻造过程进行模拟仿真。通过仿真和实验结果的对比分析来验证模型的可行性,并进一步对模型的可行性进行分析,以明确锻件温度和尺寸变化关系模型的实际意义,为优化锻造工艺提供可靠地理论依据。
[Abstract]:Large-scale forgings are the core parts of modern industrial equipment, and the production technology and forging level of large-scale forgings are one of the important symbols of national manufacturing force. Under the condition of high temperature, the manufacturing process of large forgings is very complex, energy consuming and material consuming, and the cost is enormous. Therefore, the quality assurance of large forgings and the improvement of forging technology are of great significance to the improvement of manufacturing productivity and national economic benefits. In the hot forming process of large forgings, the important theoretical basis of forging process optimization comes from the research of technological parameters such as forging size, temperature, ratio of height to diameter, reduction of weight and so on. Among the many parameters of forging process, the forging size and temperature can be obtained directly and in real time by modern advanced measurement methods, which lays a foundation for further study on the variation law of forging size and temperature and the relationship between them. To master the changing law of forging dimension and temperature in real time and the relationship between them can adjust the forging process in time and effectively, thus greatly improve the internal quality and forging precision of forging parts. Thus, it provides a reliable theoretical basis for optimizing forging process. Therefore, based on the real time measurement of forging size and temperature during forging process, a model of the interaction between forging size and temperature is constructed in this paper. Firstly, based on the heat conduction theory and the heat source theory, the temperature field under the influence of the change of the size of the hot forging is analyzed, and the temperature field of the forging is decomposed into two temperature field functions of temperature drop and temperature rise. Combined with the measurement information of forging size and temperature during forging process, the formula of heat transfer coefficient is corrected when the forging size changes, and the temperature field function of forging is obtained by using two-dimensional unsteady heat transfer model. Based on the principle of energy conservation, the function relation function of forgings with dimension change is constructed, and the function conversion coefficient is further improved. Based on the function of forging, the temperature field function of forgings during temperature rise is obtained by using the virtual heat source method in movable coordinate system. The temperature field model of forgings when the size of forging is changed is constructed by adding the temperature field function of the forgings with temperature drop and temperature rise. Secondly, based on the changing process of internal forming quality parameters and the characteristics of internal stress change of hot forging, the influence of forging temperature on the change of forging size is analyzed from different angles. The multivariate function differential method is used to obtain the relation function between the dimension change and stress of forgings. Based on the energy function and dimension strain formula of forgings during deformation, the parameters of energy deformation of forgings are analyzed and solved in order to obtain the relationship function between temperature and stress of forgings. The model of dimension change under the influence of forging temperature is constructed with the stress of forging piece as the intermediate variable. Finally, based on the model of temperature and dimension change of forgings, the forging simulation experiments are constructed by using the laboratory and forging field conditions to obtain the forgings' measurement information and experimental results. The forging process is simulated by Deform-3D software. The feasibility of the model is verified by comparing the simulation results with the experimental results, and the feasibility of the model is further analyzed in order to clarify the practical significance of the relationship between the temperature and the size of the forgings. It provides a reliable theoretical basis for optimizing forging process.
【学位授予单位】：燕山大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TG316

【参考文献】