Thermo-mechanical coupled analysis of hot ring rolling process

A 3D rigid-plastic and coupled thermo-mechanical FE model for hot ring rolling（HRR） was developed based on DEFORM 3D software, then coupled heat transferring, material flow and temperature distribution of the ring in HRR were simulated and the effects of process parameters on them were analyzed. The results show that the deformation nonuniformity of ring blank increases with the increase of the rotational speed of driver roll and friction factor or the decrease of the feed rate of idle roll and initial temperature of ring blank. The temperature nonuniformity of ring blank decreases with the increase of the feed rate of idle roll or the decrease of initial temperature of ring blank and friction factor. There is an optimum rotational speed of driver roll under which the temperature distribution of ring blank is the most uniform. The results obtained can provide a guide for forming parameters optimization and quality control.     

Deformation behaviors and conditions in L-section profile cold ring rolling

Three-dimensional FE model of plastic penetration in L-section profile cold ring rolling is established under ABAQUS software. Based on this model, the expanding rules of plastic zone in roll gap are revealed by FE simulation, and three deformation behaviors of L-section ring that exist in the rolling process are exposited. Conditions for three deformation behaviors are studied and verified by rolling simulation and experiment. The deformation behavior, which is needed for normal rolling of L-section ring, and its conditions are determined at last.     

Investigation of rolls size effects on hot ring rolling process by coupled thermo-mechanical 3D-FEA

Hot ring rolling is a significant branch of ring rolling characterized by high nonlinearity, 3D deformation, continuously progressive forming, unsteady-state, asymmetry, etc. with coupled thermo-mechanical behaviors which have significant effects on the deformation behavior, microstructure and mechanical properties of the ring. Changing the sizes of forming rolls including mandrel and driver rolls will considerably affect the roll gap deformation zone which is in close relation to the feed amount of both forming rolls and thus affects forming quality of the ring as well as power parameters. In this study, a reliable coupled thermo-mechanical and 3D rigid-plastic finite-element (FE) model for hot rolling of large rings is established. Then, based on the stable forming condition of the ring rolling process and comprehensive numerical simulations, the size effects of forming rolls on strain and temperature distributions and their uniformity, stress distribution, side spread and power parameters were investigated by 3D coupled thermo-mechanical FE simulation. The results show that there are optimum sizes of mandrel and driver rolls under which the strain and temperature distributions of ring and thus its microstructure are the most uniform where fishtail coefficient and power parameters have reasonable values. The achievements obtained can not only serve as a guide to the design of rolls sizes, optimization and quality control of the hot ring rolling process, but also clarify the plastic deformation and heat transferring of hot rolling of large rectangular-section rings.     

摩擦对高温合金复杂截面圆环多道次滚压成形不均匀变形作用

在高温合金复杂截面薄壁圆环多道次滚压成形过程中,板料要经历多场多因素偶合作用下复杂的不均匀塑性变形和组织演化历程,特别是不均匀塑性变形通常是导致薄壁件成形起皱、椭圆和开裂等缺陷产生的主要因素。摩擦是描述环件与辊轮接触作用的主要参数,很大程度上决定着该环件多道次滚压成形过程中塑性变形的不均匀性,严重的影响着其滚压成形质量。为此,本文以有限元仿真为主并结合实验和理论方法,对高温合金GH4169薄壁w形圆环多道次滚压成形进行了系统的分析;进而提出了不均匀变形度的表征方法,研究获得了摩擦对高温合金复杂截面薄壁圆环多道次滚压成形不均匀变形的影响规律。结果表明：随着滚压成形的进行等效应力极值逐渐增大,且从动辊进给时环件弯曲部分材料变形量较大;随着驱动、从动辊与环件之间摩擦系数的增加,不均匀变形程度先减小,后逐渐增大;导向辊与环件之间的摩擦对不均匀变形度的影响不大。     

42CrMo铸坯环件热辗扩有限元模拟与分析

基于ABAQUS软件平台,建立了42CrMo大型环形铸坯热辗扩三维热力耦合有限元模型,模拟了铸坯热辗扩过程中应变场和温度场,研究了初始辗扩温度对辗扩力的影响规律.模拟结果表明在环形铸坯热辗扩过程中：①铸坯等效应变呈阶梯状上升,内外表面应变大于中间层应变;在稳定成形阶段,沿环件径向方向,由于导向辊与芯辊直径差异,导致环件最大平均等效应变可能出现在环件内表面也可能出现在环件外表面;②初始阶段,变形区与成形辊接触处温度降低较快,非变形区温度变化不是很明显;随着辗扩的进行,芯部温度逐渐上升,边缘温度低,温度分布不均匀;③随着铸坯初始辗扩温度升高,平均辗扩力明显下降,但随时间变化趋势保持一致.     

钛合金大型环件热辗扩成形应力-应变场演变规律的尺寸效应(英文)

基于可靠的钛合金大型环件热辗扩成形过程热力耦合三维有限元模型,研究并对比了不同尺寸环件的应力应变场演变规律。结果表明:对于不同尺寸环件的成形过程,当γ(整个成形过程的当量每转进给量分配比)减小时,成形结束时的Mises应力峰值可能从环件的驱动辊侧咬入点转移至芯辊侧咬入点,而等效塑性应变峰值有从环件外表面向内表面转移的可能性;当L(整个成形过程的当量变形区长度)增大时,成形结束时的Mises应力峰值可能出现在中间层。成形结束时Mises应力峰值和等效塑性应变峰值的位置是以上两方面综合作用的结果。在成形环件的变形区,环件表层金属处于三向压缩应力状态,中间层金属处于一向压缩、两向拉伸或者两向压缩、一向拉伸应力状态;整个环件处于一向压缩、两向拉伸应变状态。     

高温合金复杂截面薄壁圆环多道次滚压成形截面变形特征

高温合金复杂截面（W）圆环多道次滚压成形截面变形十分复杂,而滚压圆环截面成形质量又决定了其服役性能。基于ABAQUS/Explicit软件平台,建立了"W"圆环多道次滚压的三维弹塑性有限元模型,并试验验证了其可靠性。基于所建立的有限元模型,分析环件多道次滚压成形过程中截面变形的特征。结果表明:滚压成形后,环件上应力最大处的截面沿宽度方向最外缘与其理论值的差值最小,最小截面变形位于应力较大处且随着滚压道次的增加最小截面变形位置保持不变。研究结果可为高温合金多道次滚压成形过程中环件复杂截面变形的预测和控制提供指导。     

GH5188密排孔薄板滚弯成形孔变形特征分析

在解决了高温合金GH5188密排孔薄板三辊非对称滚弯成形有限元建模中的材料模型、几何模型、网格划分等关键技术问题后,建立了密排孔薄板三辊非对称滚弯三维有限元模型,并实验验证了该有限元模型的可靠性。基于获得的仿真结果和理论分析,提出了密排孔薄板滚弯成形孔变形的定量表征方法,分析了密排孔薄板三辊非对称滚弯成形过程中孔的变形规律。结果表明:孔变形后,外表面孔的扩张量略大于内表面孔的压缩量,在滚弯过程中孔的变形量有轻微波动,略有增大;沿成形件同一轴向上的孔的变形量差值极小;沿成形件同一周向上的孔的变形量是波动变化的,但差值很小。     

基于新晶体塑性模型预测织构演化的环件冷轧变形机制

提出一种新的多晶体塑性模型以从织构演化角度研究环件冷轧过程的变形机制。该模型是在晶体塑性理论框架内通过推导一套线性增量控制方程建立的。该模型可以用线性求解方法直接求解,并采用一个两步法的求解过程,确保模型计算的效率和稳定性。基于ABAQUS/Explicit平台开发了用户材料子程序VUMAT,以实现该模型与环件冷轧三维有限元模型的结合。结果表明,该模型在预测动态复杂成形过程中的应力应变响应和织构演化方面都是可靠的;从轧制环件中很强的Goss织构{110}？100？看出,环件轧向的剪切变形是环件冷轧过程中的主要变形;环坯的织构和晶体结构对轧制环件中的织构类型的影响不大;在冷轧的后期环件织构演化迅速,这导致了这一时期环件的快速长大。     

Dynamic explicit FE modeling of hot ring rolling process

1Introduction Ring rolling is an advanced process typically used to manufacture parts with revolved geometries.It makes use of rotating rolls to press a ring continuously and locally,causing the wall thickness of the ring to reduce,the diameter to expand …     

稳定夹送辊理论设计方法

以带钢不产生塑性变形、空转辊不打滑为原则,研究稳定夹送辊理论设计方法。建立了夹送力计算模型、带钢临界塑性变形模型、空转辊打滑模型,将三个模型耦合迭代,理论计算了稳定夹送辊传动电机功率、辊径及空转辊空间布置尺寸,确保带材不会产生塑性变形和擦划伤。比较原有的经验设计方法,更加准确、可靠。     

驱动辊转速对环件轧制工艺影响规律研究

针对环件轧制成形规律,以数值仿真和数学解析相结合的方法,以有限元分析软件ABAQUS为平台,建立弹塑性动态显式有限元模型,研究驱动辊转速对环件成形工艺的影响。研究表明,在环件轧制过程中,随着驱动辊转速的增加,每转进给量减小,外径部分金属轴向流动增加,环件自由端面形状系数FT增加,最大宽展系数增加,环件自由端面质量下降;在驱动辊转速增加过程中,轧制力和轧制力矩减小,对轧环机的力学性能要求降低。同时平均等效应变PEEQa增加,环件塑性变形程度增大,有利于提高环件力学性能,但同时变形不均匀程度也加大,内部质量缺陷的可能性增加。     

Numerical Study on Motions of Rolls in Hot Rolling of Titanium Alloy Large Rings

由于钛合金对应变速率十分敏感,因此轧辊运动对钛合金大环热辗扩成形过程有重要作用。提出了相对速率vr的概念来表征轧辊运动参数的综合作用,涉及的运动参数包括驱动辊旋转速率n1和芯辊进给速率v,并且基于稳定成形条件采用解析方法确定了vr的合理取值范围。其次,运用动力显式有限元程序ABAQUS/Explicit 建立了可靠的钛合金大环热辗扩成形过程的热力耦合三维有限元模型。最后,采用有限云模拟方法,探究了vr对该成形过程的影响效应及其机制。结果表明;尽管通过减小n1来增大vr与通过增大v来增大vr 均使每转进给量△ hi 增大,但它们对成形过程的影响效应并非完全一致,比如对非均匀应变分布的影响;较大的vr有助于提高成形环件的端面质量和应变与温度分布的均匀性,但对成形力有不利影响。     

径-轴双向环轧工艺的研究进展

回顾了环件径-轴双向轧制锻透条件、咬入条件、刚度条件等相关理论研究进展，分析了工艺参数对轧制过程的影响及其确定准则，在此基础上引入轧制曲线的概念，并给出了径-轴双向环轧轧制曲线的设计原则，还探讨了在利用有限元方法模拟轧制过程、优化轧制工艺参数时存在的问题，并给出了对数值模型进行控制和处理的有效方法。     

滚压有限元模型数值模拟

滚压数值模拟是制定滚压工艺、预测滚压后工件表面残余应力分布,以及判定工件疲劳性能的重要工具。目前的滚压数值模拟主要集中在对曲轴以及回转体的分析,少有的对平面滚压数值模拟中,大多数也只分析了单圈或不到一圈的滚压过程,而且与实际滚压工艺存在较大的区别。为弥补以上不足,该文采用有限元商业软件ABAQUS提供的Explicit模块,并结合python编程语言,开发了更接近于实际的滚压模拟过程;采用该模型研究了滚压力的大小、滚针直径、表面摩擦系数等对于残余应力分布规律的影响,并通过H13钢的滚压实验,对模型模拟结果进行了验证。     

厚板轧机轧制区接触状态的有限元分析

应用大型非线性有限元软件MSC.Marc,建立了三维动态弹塑性全辊系有限元模型,对四辊轧机轧制厚带钢的过程进行模拟。与以往模型相比,该模型充分考虑了由于窜辊、辊形、单侧驱动等客观因素带来的辊系不对称特点,最大程度上减少了假设。基于模型,深入研究了不同带钢宽度时,轧制区轧件与工作辊间接触压力及摩擦力的三维分布情况,对研究厚板四辊轧机与带钢的接触状态及相关问题的解决,提供了理论依据。     

Research on gripping conditions in profile ring rolling of raceway groove

Ring gripping means that under the pressure of roll and friction, ring grips the rolling gap and produces rotating rolling motion, thus ring thickness receives equal rolling and the outer diameter expands equally, and this is a sufficient condition for ring rolling forming. In this paper, gripping course in profile ring rolling of raceway groove is analyzed based on ring rolling principle and static theory. The gripping mechanical model for profile ring rolling of raceway groove is established, and gripping conditions are researched according to the geometrical relationship in rolling. The results indicate that ring could be ensured to continuously grip the gap in rolling by controlling feed per revolution and preventing it from exceeding the maximum feed per revolution allowed by ring gripping. Furthermore, influencing factors of gripping conditions are analyzed. At last, the experiments and the FE simulation for profile ring rolling of raceway groove are performed to testify the validity of gripping conditions. Both the experimental and simulation results show that when feed satisfies gripping conditions, ring can continuously grip the gap and be formed by rolling. Otherwise, ring cannot grip the gap and is squashed between the rolls. The results of this research provide a theoretical basis for design of technological parameters of profile ring rolling of raceway groove.     

Continuous extrusion and rolling forming velocity of copper strip

A new copper strip production technology combined with continuous extrusion and rolling technology was proposed. The roll velocity must first be matched with the continuous extrusion velocity to achieve continuous extrusion and roll forming. The bite condition of continuous extrusion was determined, and the compatibility equation between the roll velocity and parameters such as the extrusion wheel velocity, reduction, and strip size was established through mechanical by plastic theoretical calculations. The finite element model of continuous extrusion and rolling was then established by using the TLJ400 continuous extrusion machine with a roll diameter of 200~mm. The relationship between the continuous extrusion and rolling velocities was determined through numerical simulations by software DEFORM-3D, and the accuracy of compatibility equation of velocity was verified.     

车轮轧制成形过程的有限元模拟

采用DEFORM-3D建立车轮轧制过程三维有限元分析模型,在建立轧制过程的数学模型和开发轧辊运动的控制算法,并与DEFORM软件集成的基础上,模拟了实际轧制过程中轧辊的运动。从轧制力对比与轮坯几何形状的分析两方面验证了模型和控制算法的可靠性;分析了轧制过程中材料的流动规律,为改进轧制工艺提供了参考。     

棒线材多道次轧制过程的静力隐式有限元模拟及模型优化

借助有限元分析软件MSC.Marc,采用三维热机耦合有限元模型和静力隐式算法,对多道次连轧稳态轧制过程进行模拟分析。模型中轧辊间距采用真实尺寸。基于静力隐式算法的特性,在优化模型中引入刚性推动体,实现模型的简化。比较优化前后两种有限元模型的模拟结果及参数,表明该文所建立的优化模型可以在保证较好的计算精度前提下,显著地提高运算效率。应用优化模型模拟粗轧六道次连轧过程,温度变化模拟结果与实际测量结果吻合较好。