含铌HSLA钢板带热连轧过程非均匀应变的数值研究

 利用ANSYS/LS DYNA建立了板带轧制过程的三维热力耦合有限元模型,通过有限元模型探讨了轧件入口厚度、轧件温度、工作辊直径、压下率和化学成分中的铌含量对变形区应变分布的影响。模拟结果表明,这些因素都不同程度地影响轧件厚度方向的应变分布,对于试算的CSP流程,适量增加铸坯厚度,并在较靠前的机架分配较大的压下量有利于提高轧制过程的应变均匀性。     

基于辊缝动态摩擦方程的铝板冷轧机垂振机理分析

针对高速铝板轧制过程中频繁出现的冷轧机垂直振动现象,结合轧制工艺润滑原理和机械振动理论,建立基于辊缝动态摩擦方程的轧机垂直振动模型.该模型由辊缝几何形状模型,轧辊-轧件工作界面的动态摩擦模型,变形区内的正向轧制应力、摩擦应力分布模型,以及单机架铝板冷轧机二自由度垂向系统结构模型组成.同时,为研究轧辊-轧件工作界面动态摩擦机制影响下的冷轧机垂振机理及系统稳定性,采用某厂单机架铝轧机设备及工艺参数,搭建Matlab/Simulink平台,分别模拟仿真轧制压力和正向轧制应力曲线,验证该模型的有效性;并讨论分析了变形区混合摩擦状态,轧辊-轧件表面粗糙度、轧件入口厚度与系统稳定性的关系.      

精轧开轧温度对Q235B连轧过程的影响规律研究

本文基于ABAQUS/Explicit平台建立了Q235B热连轧的三维弹塑性热力耦合有限元模型,分析了精轧开轧温度对成形环件的应变和温度分布不均匀性以及轧制力能参数的影响规律,同时进行了现场轧制实验的验证。结果表明:随着开轧温度的增加,轧件的温度分布愈来愈不均匀,等效应变分布愈来愈均匀,轧件中部的等效应变增大,轧制力、轧制力矩逐渐减小。     

铝箔粗轧第一道次轧件应力应变的三维有限元分析

采用DEFORM-3D有限元软件模拟铝箔粗轧第一道次轧件的轧辊转速和压下率对有效应力和有效应变的影响。铸轧坯料为铝合金1235,采用两辊轧机,轧辊直径为Φ180mm,辊宽为450mm。在DEFORM-3D软件中建立铝箔坯料的四分之一模型,宽度为205mm,长度400mm,厚度为3mm。轧辊温度为60℃、坯料温度为450℃。通过跟踪坯料上表面中心线不同位置点的等效应变和等效应力,分析讨论了轧辊转速为0.75rad/s、1.5rad/s和3rad/s,压下率为50%、57%和64%对轧件有效应变和有效应力的影响。研究结果表明:随轧辊转速和压下率的增加,有效应变变大,达到最大有效应变的时间增加;有效应力变大,达到最大有效应力的时间增加。较佳的轧辊转速和压下率为3.0rad/s和57%。     

1650铝箔粗中轧机的轧制油系统分析

加工硬化使金属的变形抗力增大,金属的变形热与摩擦热使轧件和轧辊的温度升高,辊系间的热量流动使轧辊轴向温升不均匀,产生热凸度。所以选择合适的冷却润滑剂,对控制板形十分重要。其中轧制油的工作温度、工作压力、流量和分布是主要影响因素。简述1650铝箔粗中轧机的轧制油系统的原理、设计、管道的安装及设备的设计。     

Ti-811合金棒材热连轧过程有限元数值模拟及验证

采用有限元法对Ti-811合金棒材热连轧过程进行数值模拟,分析变形过程中轧件应力场、应变场和温度场的数值以及分布规律,并基于数值模拟结果进行轧制验证,为制定Ti-811合金棒材轧制工艺提供指导。结果表明：模拟连续轧制过程中轧件的最大应力位于与轧辊接触的表面,且由边部到心部逐渐降低;随着轧制道次的增加,应力值逐渐下降、应变量逐渐增大;轧件在各道次的变形过程中表层和心部存在差异,心部变形量大于边部变形量;轧件与轧辊接触的表面层有明显温降,当轧件脱离轧辊后表面层温度逐渐回升,轧制结束后表面层温度回升至初始温度,但心部因变形热积聚温度略有升高,最大温升值达到14℃。基于数值模拟结果在热连轧机组上进行轧制验证,所轧制的Ti-811合金棒材外形尺寸良好,且组织与力学性能满足GJB 9567—2018《叶片用TA11和TC6钛合金棒材规范》要求。     

轧辊断面对厚扁钢轧制时金属流影响的研究

以前的文献曾指出，对热轧扁钢精度有决定性影响的是板坯断面厚度的不均匀性。而板坯厚度不均匀性取决于钢锭(轧件)在水平轧辊中和在立式轧辊中的变形制度，并取决于水平轧辊磨损的不均匀程度。轧件用立式轧辊变形后，末端会出现“舌头”状的夹层，因为边缘部分的金属既纵向流动又横向流动。用立式轧辊进行压下时，在边缘可以观察到金属既有纵向流动又有沿高度方向的流动，结果在末端形成“鱼尾”状夹层和边缘结疤。     

铝合金热轧板带成形过程中的应变数值模拟

采用有限软件Deform-3D对6061铝合金三道次的热轧进行了数值模拟。每道次以有效应变为实验指标,压下率、轧件温度和轧辊温度为实验因素进行正交实验,用云图直观地反映出各个轧制结果的板型质量情况,并通过多组试验对影响板型的参数压下率、轧件温度和轧辊温度进行了分析,来揭示其对6061铝合金板带板型质量的影响规律。     

轧辊半径对轧件变形影响的有限元分析

采用三维大变形热—力耦合有限元法分析了热轧板带时不同轧辊半径对变形区内轧件变形的影响。得到了不同轧辊半径下变形区内等效应变、剪切应变和应变能量密度的分布规律。结果表明在其他条件相同的情况下,轧辊半径越大,变形区内的变形也越大。该结果对组织细化具有一定的指导意义。     

热轧带钢传热模拟及变形区换热系数的确定

采用数值模拟方法研究了带钢热轧区轧件传热和温度场分布规律.结合现场生产中测温数据,建立了轧制变形区内轧件与轧辊接触传热界面换热系数(HTC)统计模型.分析了辊缝变形区中轧件断面上温度演变和分布特点.研究结果表明,热轧带钢热轧区传热数值模拟计算结果与实际吻合良好;变形区内轧件与轧辊接触传热界面换热系数不仅与平均单位压力相关,而且与轧制速度相关;轧件在轧制变形区存在很大的温度梯度.     

Friction Model for Strip Rolling

To improve the accuracy and speed of finite element calculation,a new friction model was proposed,in which a layer of thin friction element between the roller and workpiece was introduced to consider the contact friction.This model was used in the three-dimensional elastic-plastic finite element model of strip rolling process.Taking the geometrical size and physical characteristics of intermediate medium between roller and workpiece into consideration,the stiffness of the friction element was corrected by two factors,i.e.,the thickness of friction element and β factor.Without any assumption about the value and direction of friction force and neutral point position,the rolling process was simulated by using this model.The results obtained by this model were compared with the experimental results and the feasibility of the model was verified.     

2030板带冷连轧系统在线控制模型接触摩擦应力分布

采用弹塑性有限元法对带钢冷轧过程中接触区摩擦应力进行了模拟，分析了各种因素对摩擦应力分布的影响。利用数值方法对各影响因素对摩擦应力分布的影响进行参数拟合，从而建立各影响因素和摩擦应力分布间的特定关系，并对计算轧制力数学模型中的摩擦应力分布进行修正，使计算结果更为精确。     

Modeling the Thermal Fields of Deposited Materials During the Spray Rolling Process

The technology of spray rolling can be applied to manufacture strips with a uniform cooling rate and a high production rate. The cooling behavior of the spray-rolled material prior to rolling contact was studied using mathematical models, tracing the accumulation of multi-layers with respect to time. Thermal history, elastic–plastic, and friction behavior of the material were considered in the complicated rolling process. The developed model had a good agreement with experimental results with potential to be utilized for prediction of the spray-rolled material thermal profile. Results show that the temperature of deposited materials prior to/or during rolling and the total equivalent plastic strain distribution in the deformation zone of deposited materials during rolling increase with increasing roller preheating temperature, the initial droplet temperature, and the mass flux distribution of the spray cone. Moreover, the deposit thickness and enthalpy remaining in the deposit are found to be the dominant influencing factors on the thermal field of deposited materials during the spray rolling process.     

厚壁无缝钢管张减过程横向壁厚不均研究

为解决热轧厚壁无缝钢管横向壁厚分布不均的问题,建立三维热力耦合有限元模型,对张力减径轧制过程进行了动态模拟,并结合工业试验验证仿真模型.根据仿真结果分析了轧制过程中温度、应变和摩擦力的分布,研究了单道次轧制时金属的径向和周向流动规律,并结合整个轧制过程对金属的横向流动及壁厚不均的形成过程进行了分析,研究了轧制过程中温度对金属流动行为的影响,从而总结出横向壁厚分布不均的原因.结果表明:(1)在经过单道次轧制时,金属的周向流动为从孔型顶部流向辊缝,对应孔型角±30°位置处金属的周向流动最活跃,靠近孔型顶部和辊缝位置的金属周向流动性较差.但从整个轧制过程来看,金属总的周向流动为从孔型顶部和辊缝向孔型角±30°位置处流动,从而导致孔型角±30°位置处的壁厚比孔型顶部和辊缝位置要厚.(2)温度分布对金属横向流动有重大影响.由于塑性功换热的原因,孔型角±30°位置处金属的温度比辊缝和孔型顶部处高,此处金属较软,阻力较小,孔型顶部和辊缝处金属向此处的流动性增强,导致钢管截面呈内边方形.      

热镀锌机组沉没辊系受力模型及影响因素

热镀锌机组沉没辊系在锌锅内工作状态下受力情况复杂,受外界影响较大。充分考虑热镀锌机组设备与其工艺特点,首先分析沉没辊系在工作状态下受力情况,分别建立矫正辊插入量与包角的关系式、基于辊面锌渣沉积厚度的辊面摩擦因数经验模型。随后采用条元离散法建立沉没辊系辊面接触压力、摩擦驱动力矩模型,基于简支梁模型确定沉没辊系轴端支撑力、轴端摩擦阻力矩模型。最后将沉没辊系受力模型应用于国内某热镀锌机组镀锌工艺段,以典型规格带钢确定沉没辊系受力影响因素,并依据机组实际工况及板形要求来确定生产工艺参数的5种不同水平,来分析其对辊系受力状态的影响规律,为沉没辊系工艺优化提供指导依据。结果表明,4种工艺参数对辊系接触压力及摩擦力矩影响都存在差异性,矫正辊插入量与辊面接触压力呈现非线性关系;带钢张力对各辊接触压力影响程度不同,其中沉没辊受到的影响最大,而其余两辊受到张力几乎不影响;辊面平均摩擦因数、带钢速度对辊的接触压力几乎不影响;辊系摩擦驱动力矩、轴端摩擦阻力矩随着矫正辊插入量及辊面平均摩擦因数增大都呈现出不同程度增大。带钢张力与沉没辊摩擦驱动力矩、轴端摩擦阻力矩呈线性变化关系,而带钢张力对其余两辊影响很小。带钢...     

板坯结晶器钢液流动传热和摩擦行为的数值模拟

结晶器摩擦力对连铸顺行非常重要,而钢液流动行为会影响铸坯温度场和保护渣分布,可能对铸坯摩擦力产生一定的影响.利用Fluent软件建立结晶器内钢液流动、传热三维数学模型,并将温度场数据导入Ansys计算铸坯应变,然后根据铸坯-保护渣-结晶器摩擦行为数学模型讨论了渣膜润滑情况,对比了不同水口底部形状下结晶器内液态、固态和总摩擦力.结果表明:不考虑水口射流时结晶器总摩擦力比考虑水口时增大约29.4％;浸入式水口底部形状分别为凸底、平底和凹底3种情况下铸坯窄面中心温度依次降低,凝固壳厚度依次增大,固态摩擦力依次增大,总摩擦力依次增大,液态摩擦力相差较小.     

The Influence of Support Rollers of Continuous Casting Machines on Heat Transfer and on Stress‐Strain of Slabs in Secondary Cooling

The processes of solidification and heat extraction are important for the continuous casting of steel. In this work, investigations on the influence of support roller contact on solidification in a strand of a slab caster, such as surface temperature and strand shell growth, and on thermal strain and stress in the slab have been carried out. The results show that roller contact has an influence on the solidification of steel and on the thermo‐mechanical behaviour of the strand.     

Effects of Pin Shape on the Tool Plunge Stage in Friction Stir Welding

Studying each stage of the friction stir welding (FSW) in detail provides a more complete understanding of the process. In this study plunge stage in FSW has been studied experimentally. Effects of pin shape on the temperature distribution around the tool during the plunge stage have been examined by placing thermocouples around the tool in the workpiece and measuring the temperature during the process. Tools which had square, triangle and cylindrical pin shape were used to investigate the effects of pin shape on the temperature of the workpiece. Temperature distribution was asymmetric around the tools and temperature was a little higher behind the tools and at advancing side. The arrangement of the points according to the temperature was similar in all samples. It was found that most of the heat is generated by friction and the effect of friction on the workpiece temperature was more than plastic deformation. Shoulder had more considerable effects on the workpiece temperature compared to the pin.     

The ring compression test as simulation test for the investigation of friction in hot metal forming

Forces and flow of material in metal working decisively depend on friction between workpiece and tool, which can be described by the friction factor m. For investigation of the influence of friction in hot forming of steel and for measurement of the friction factor, the ring compression test is used as simulation test. The influences of material, reduction, strain rate, temperature, and lubricant are discussed.