金属体积成形过程中温度场的分析

以耦合的方式来处理体积成形过程中塑性变形和温度场之间的相互影响和相互作用 ,开发了一套能进行热力耦合分析的刚塑性 /刚粘塑性有限元模拟软件HFORGE2D ,并利用该软件对镦粗过程和模锻过程进行了数值模拟 ,揭示了成形过程中塑性变形和温度场之间的内在联系     

板坯连铸结晶器传热反算方法研究

基于连铸生产中实时监测结晶器受热状态的需要，建立了结晶器铜板水平截面的二维热传导模型，提出了基于最小二乘法原理的传热反问题数值计算方法，并在VC＋＋6．0平台下编制了计算程序。程序中利用控制容积法建立离散方程组，采用一维变带宽存储、holesky分解技术，提高了计算速度。通过与商业软件计算结果的对比，证明了二维假设的合理性。对一组实测数据进行分析，验证了算法和程序的可靠性，从而为实现连铸过程监控提供了可借鉴的实用方法。     

铝卷径向接触热阻的仿真研究

对铝板进行加热试验,得到各测试点的温度数据.通过热传导反问题的求解,求得铝板间的等效导热系数,将其等效为铝卷径向导热系数,从而间接求得铝卷接触热阻,并推导出了铝卷强对流传热系数对温度的数学表达式.运用ANSYS有限元分析软件,综合考虑铝卷的导热系数和对流换热系数随温度变化的非线性,模拟了铝卷退火过程中的瞬态温度场.仿真结果表明,铝卷内部的温度与实测结果比较吻合,从而证明了试验方案和铝卷径向接触热阻求解方法的正确性,同时为铝卷退火工艺的优化提供了理论依据.     

辊式淬火机淬火冷却过程温度场仿真

选取辊式淬火机为研究对象,通过分析钢板冷却过程传热机理,建立了钢板热传导数学模型。采用外节点法和有限差分方法分别对计算区域和控制方程离散化处理,运用VB.NET语言编写程序,对钢板淬火冷却过程温度场进行仿真研究。结果表明,本文所建立的淬火过程热传导数学模型可以作为淬火机二级控制系统的基础,进行过程控制系统的开发。     

复杂锻件净成形过程温度场的数值模拟

本文以数值模拟方法为工具,以齿轮温态净成形（Ｎｅｔ－ＳｈａｐｅＦｏｒｍｉｎｇ）工艺为对象,研究了复杂锻件净成形过程热力学因素对工件／模具系统的影响。重点探讨了工件与模具的接触传热问题及使用有限元程序分析计算的实现方法,并验证了其正确性。模拟分析得到的温度场可用于模具寿命和锻件精度的预测。     

异型坯连铸结晶器铜板温度场及改进方案研究

异型坯连铸结晶器铜板的温度场是控制钢坯质量的重要因素之一。针对某近终形异型坯连铸结晶器,考虑钢水和结晶器铜板之间的接触传热以及铜板镀层和保护渣的热阻,给出了钢水和结晶器铜板之间的综合换热系数,进而采用ABAQUS有限元软件对结晶器铜板的温度场进行数值模拟。给出了不同铜板厚度、不同冷却水流速以及改进水槽和水孔设计等方案下铜板的温度场,为铜板的优化设计提供依据。     

粗轧变形区温度场实验及仿真

轧制变形区温度场的分布是轧制力及轧件微观结构预测的重要参数之一。采用实验和有限元的方法研究了铝板热轧过程,侧重轧件变形区温度的分布,并对变形区接触热传递系数的分布规律进行了分析;以此作为轧辊轧件间传热模型,建立了实验轧制的数学模型。结果表明,轧件在轧制变形区存在较大的温度梯度,并且与实验结果吻合较好。     

热连轧高适应度工作辊温度场计算模型的研究

热连轧生产中,工作辊与冷却水换热系数和工作辊与轧件换热系数是工作辊温度场计算模型中的关键参数,为了提高工作辊在线温度场计算精度同时降低其复杂性,以一维热传导实验结论为基础,建立换热系数随工艺因素变化的数学模型,采集多组不同典型轧制工艺条件下实测工作辊温度数据并利用遗传算法求解模型待定参数,确定了工作辊与冷却水、工作辊与轧件的换热系数计算模型。结果显示,与常规温度场计算模型相比,包含换热系数计算模型的在线温度场模型的计算精度提高30.6%。     

工程车辆油气悬挂温度场影响因素分析

油气悬挂内部物理状态对其输出特性具有重要影响,其中温度场的变化是不可忽略的重要因素。根据油气悬挂的结构特点,搭建力学模型;基于传热学理论,考虑了缸筒和活塞杆的热容对油气悬挂温升的影响,运用集中参数热模型法建立了油气悬挂的热力学模型,并将其与油气悬挂的非线性输出力数学模型相结合,得出了油气悬挂温度变化的规律。搭建油气悬挂周期激励试验台,通过油气悬挂热力学模型的计算结果和油气悬挂周期性激励加载的试验结果都表明:油液是影响悬挂温升的主要内部因素,而且在外界激励存在的情况下,由于与外界环境的热量交换,悬挂的温度会逐步达到一个平衡的状态;同时试验结果中输出力的变化趋势表明:悬挂系统温度变化对悬挂输出力的影响是不能忽略的,在实际中应加以重视。     

固体界面接触换热系数影响因素的实验研究

通过自制的接触换热系数测量设备对铝合金与5CrMnMo模具钢、不锈钢与不锈钢间的接触换热系数进行了实验研究,分析了接触换热系数随温度和压力的变化趋势,并且分析了改变接触过程后接触换热系数的变化.实验结果发现,接触换热系数与温度的关系并不是简单的正比关系,而是与载荷近似成正比关系;且在其它接触条件相同的情况下,如接触过程的升温过程和降温过程、加载过程和卸载过程等不同,接触换热系数的测量值也不同.     

浅谈曲轴自由锻造的下料计算

阐述了曲轴自由锻造下料计算时，如何确定烧损、工艺用料等一些实践性较强的问题，通过多年生产实践，得出了一些相应的经验数据。     

Equivalent heat transfer coefficient at casting/Cu mould interface and temperature field simulation

1　INTRODUCTIONThesolidifiedmicrostructuresofalloysdependontheirsolidifyingprocesswhoseprimarycharacteristicsarethetemperaturedropofthesuperheatedmeltandthere leaseofthelatentheat.Sothestudyontheheattransferduringthesolidificationprocessistheessentialprobleminthesolidificationtheorystudy .Theresearchersworkingonthenumericalsimulationofthesolidificationprocessallknowthattheinterfacialheattransfercoefficientatthecasting/mouldisavariablechangingwithtime .Thusthedeterminationoftheinterfacialh…     

Regularized determination of interfacial heat transfer coefficient during ZL102 solidification process

The interfacial heat transfer coefficient（IHTC） between the casting and the mould is essential to the numerical simulation as one of boundary conditions. A new inverse method was presented according to the Tikhonov regularization theory. A regularized functional was established and the regularization parameter was deduced. The functional was solved to determine the interfacial heat transfer coefficient by using the sensitivity coefficient and Newton-Raphson iteration method. The temperature measurement experiment was done to ZL102 sand mold casting, and the appropriate mathematical model of the IHTC was established. Moreover, the regularization method was used to determinate the IHTC. The results indicate that the regularization method is very efficient in overcoming the ill-posedness of the inverse heat conduction problem（IHCP）, and ensuring the accuracy and stability of the solutions.     

大锻件锻造过程中温度场测定及其结果分析

大型锻件锻造过程中工件温度场的变化规律对于保证锻件质量具有重要作用,由于锻件受环境温度、保温情况等诸多因素影响,生产中很难准确预测锻件锻造过程中温度变化规律。通过实验模拟实际生产中锻件加热曲线,在不同保温措施下,取锻件芯部至表层不同测控点进行锻造过程中的温度测量,通过数据分析建立了Mn18Cr18N护环钢锻造过程中的温度场,得出锻件的温度差与时间变化曲线及温度变化速率图,描述了工件在一定保温措施下的温度场变化情况,其结论对准确了解Mn18Cr18N护环钢锻造过程中的温度变化规律具有实际指导意义。     

Exact and approximate methods for determining the thermal parameters of the forging process

Numerical simulation of the forged body plastic flow is a very important and indispensable technique in the mechanical forming. The correct simulation of changing the shape of a hot blank requires the use of very accurately determined physical parameters. There is thus a pressing need to create and supplement a database containing the exact physical parameters of forged materials. The following paper shows the results of development of methods to determine two thermal parameters of a solid body: the average value of the total emissivity and the average coefficient of heat transfer by convection. The methods of determining thermal parameters, described below, are considerably simpler than traditional ones, and they do not require the use of complicated equipment. The exact method is based only on processing of experimental data. In the approximate method, both the experimental data and theoretical values of thermal parameters available in the literature are used.

The developed methods were applied to determine thermal parameters of test bodies of SAE 1045 steel and ABNT 6061 aluminum alloy.     

Measurement of temperature inside die and estimation of interfacial heat transfer coefficient in squeeze casting

As an advanced near-net shape technology, squeeze casting is an excellent method for producing high integrity castings. Numerical simulation is a very effective method to optimize squeeze casting process, and the interfacial heat transfer coefficient (IHTC) is an important boundary condition in numerical simulation. Therefore, the study of the IHTC is of great significance. In the present study, experiments were conducted and a"plate shape" aluminum alloy casting was cast in H13 steel die. In order to obtain accurate temperature readings inside the die, a special temperature sensor units (TSU) was designed. Six 1 mm wide and 1 mm deep grooves were machined in the sensor unit for the placement of the thermocouples whose tips were welded to the end wall. Each groove was machined to terminate at a particular distance (1, 3, and 6 mm) from the front end of the sensor unit. Based on the temperature measurements inside the die, the interfacial heat transfer coefficient (IHTC) at the metal-die interface was determined by applying an inverse approach. The acquired data were processed by a low pass filtering method based on Fast Fourier Transform (FFT). The feature of the IHTC at the metal-die interface was discussed.     

谈碳钢的锻造温度范围

不少资料和教材都将工业纯铁等同一般低碳钢,根据碳钢的锻造温度范围确定工业纯铁的锻造温度,这必然导致工业纯铁锻件报废.碳钢正确的锻造温度范围应不包括工业纯铁.     

铝铸锭凝固边界热交换规律及温度场模拟

研究铝铸锭凝固边界热交换的变化规律及数学模型,并对不同浇注温度下凝固过程的温度场进行模拟。利用实时数据采集系统获得凝固过程中铸锭和金属模温度变化历史数据,采用非线性反算法和一维传热差分法对试验数据处理,建立界面换热模型并将其应用于凝固温度场模拟中。结果表明：在铸锭表面凝固前后凝固界面热流密度可分段用指数函数来描述其变化规律,而所建立的热交换系数与边界温度的对应关系可更好地反映实际的传热情况。模拟结果与实验测温结果相符,验证了该铸件/铸型边界热交换规律的可靠性。