无缝钢管张力减径张力系数的理论计算与分析

通过推导钢管张力减径塑性方程,提出了表征钢管张力减径时纵向、径向和切向变形的指标,计算和分析了张力系数对张力减径变形的影响特点,并定量分析了临界张力系数的特点。分析结果表明:增大张力系数有利于促进钢管的纵向延伸变形和减壁变形,不利于减径变形;在3个方向的变形中,张力系数对壁厚变化的影响最为明显;钢管张力减径时,临界张力系数的大小只受钢管径壁比的影响,径壁比越大,临界张力系数越大;理论计算的临界张力系数的范围为0.35~0.50,任何情况下临界张力系数小于0.50。通过生产应用实例证实,根据钢管径壁比选择张力系数具有实用性和有效性。     

无缝钢管微张力减径过程的数值计算

根据微张力减径机组轧制工艺,采用ANSYS/LS-DYNA大型通用有限元分析软件对无缝钢管的微张力减径过程进行了数值计算,得到了钢管经过各机架时的应力场、应变场、壁厚的分布规律,以及金属的变形状态。模拟结果能够较好地诠释钢管减径过程中出现的壁厚不均等现象,模拟结果与实际生产中钢管变形行为状态基本吻合。研究结果对于技术人员分析、制定和优化钢管减径工艺制度具有较好的实践指导意义。     

14机架微张力定(减)径过程壁厚分布的有限元研究

根据钢管微张力定(减)径过程的变形特点,利用MSC.Marc软件进行三维弹塑性有限元分析,模拟钢管通过14机架微张力定(减)径机的变形过程。通过研究钢管断面上的横向壁厚分布,分析其内多边形程度;通过研究整根钢管的轴向壁厚分布,不需进行解析计算,可直接在有限元模型上测得头尾增厚段的切除长度。据此提供分析产品缺陷、指导工艺设计的依据。     

管材张力减径有限元快速仿真系统的研究

根据张力减径过程的变形特点,采用组元建模技术,编写了弹塑性有限元计算程序。利用AutoCAD进行图形后处理,并通过VB建立人机交互界面,开发了管材张力减径过程快速仿真系统。研究了管材张力减径的变形过程,预报了轧后产品几何形状、应力、应变等分布状态。模拟结果与生产实测结果吻合良好,表明该系统能够胜任钢管张力减径过程模拟及产品质量预报工作。     

张力系数对钢张力减径管壁厚度参数的影响研究

张力系数是钢管张力减径工艺的关键参数。为了分析张力系数对钢管减径工艺的影响,首先给出了具体的钢管减径工艺张力系数和轧辊转速的关系,得出了10组不同张力系数下的轧辊转速和减径工艺参数。然后运用有限元软件ANSYS/LS-DYNA对这10组张力减径过程进行了数值模拟,分析了不同张力系数下的接触应力、壁厚、内六方程度等工艺参数。最后通过实验验证了模拟结果,得出合理的张力系数。结果对改善钢管张力减径工艺和提高钢管轧制成形质量具有参考价值。     

厚壁钢管张力减径过程的变形规律研究

荒管壁厚和张力系数是张力减径工艺的重要参数,对成品钢管质量具有直接影响。针对20机架钢管张力减径过程建立热力耦合有限元模型,并选择9种不同壁厚的钢管进行数值模拟,得到了张力减径过程中金属的流动规律,研究讨论了钢管内多边形的形成机理,总结了荒管壁厚和张力系数对张力减径工艺的影响规律。     

21机架张力减径机椭圆孔型的有限元分析

根据钢管在张力减径时的变形特点,利用ANSYS软件对21机架张力减径机进行三维建模有限元分析,模拟荒管在减径过程中的变形过程,比较圆孔型参数模拟和椭圆孔型参数模拟时荒管产生“内六方”的趋势和壁厚变化情况.分析认为,采用椭圆孔型参数模拟时,荒管产生“内六方”的趋势较小,且壁厚波动也较小.     

厚壁钢管微张力减径成型热力耦合模拟与实验研究

根据微张力减径工艺,采用大型通用有限元分析软件ANSYS/LS-DYNA对厚壁微张力减径过程进行三维热力耦合数值计算,得到了钢管经过各个机架的应力场、应变场、温度场、壁厚分布及轧制力变化以及金属的不均匀变形状态。数值模拟的结果能够较好的反应钢管壁厚不均的成因,为分析产品缺陷,为减径工艺设计提供了指导。     

厚壁管微张力减径过程有限元计算分析的实验研究

本文通过弹塑性有限元对厚壁钢管微张力减径过程中的壁厚变化作了计算分析,并与实验结果进行了对照,证明了用弹塑性有限元分析微张力减径过程是可行的,并得出一些结论,这对于用有限元手段开发新品种,推广微张力减径技术有重要的意义。     

钢管微张力减径过程中壁厚变化的有限元计算分析和实验研究

通过弹塑性有限元对几个典型品种钢管微张力减径过程中的壁厚变化作了计算分析,并与实验结果进行对照,证明用弹塑性有限元分析微张力减径过程是可行的,并得出一些结论,这对于用有限元手段开发新品种,推广微张力减径技术有重要的意义。     

Isothermal and thermomechanical finite-element analysis of the tube drawing process using a fixed tapered plug

Quality is a very important feature in the manufacturing of products such as tube. Nonhomogeneous deformation, common to most metalforming operations, leaves the product in a cold worked state, resulting in a pattern of residual stresses. Depending on the nature and magnitude of residual stresses, they may be detrimental or beneficial to the strength and reliability of the product. To evaluate the residual stresses in the product, a complete stress analysis of the workpiece throughout the deformation history is required. In this study, a large deformation, nonlinear, elastic-plastic finite-element code was used to investigate the effect of friction, drawing speed, degree of plastic work (reduction in area), and the die/plug geometry on the extent of temperature increase, induced residual stresses, and the required drawing load in the drawing of oxygen-free high-conductivity (OFHC) copper tube using a fixed, tapered plug. Complete simulations of the tube drawing process were conducted by tracing its deformation history from the point at which it entered the die area until it exited the die. The resulting thermal effects were then used to determine the required drawing loads and induced residual stress distributions throughout the tube wall thickness. Similar simulations were conducted without taking into account the thermal effects. Equivalent plastic strain, equivalent stress, longitudinal stress, and circumferential residual stresses are presented and compared for both the isothermal and the thermally coupled analysis.     

网架结构用管的研制与开发

简介了网架结构用管的发展趋势及在低碳锰钢的基础上加入适量微合金元素生产的网架结构用管的成分及生产工艺;讨论了加热制度、轧制变形、轧后冷却速度等对网架结构用管的组织和性能的影响。研究结果表明,攀钢集团成都钢铁有限责任公司所开发的几种生产网架结构用管的新工艺,通过批量生产与不断改进,已形成稳定正常的生产能力。     

TC2钛合金管材挤压工艺

研究了化学成分、挤压温度、挤压比、退火温度对TC2钛合金管材挤压成形、组织性能的影响。掌握了该合金热加工变形的特点，确定了合理的工艺路线及参数，研制的产品组织性能、表面质量及尺寸精度优良，满足相关技术标准的要求。     

MODELING OF CONTROLLED THERMO-MECHANICAL PROCESSING OF TUBES FOR ENHANCED MANUFACTURING AND PERFORMANCE

1.IntroductionApproximately15milliontonsofsteeltubeandpipeproductsareconsumedintheUnitedStatesannually.Mechanicaltubesarethefeedstocksusedinthemanufactureofrollingelementbearings,hydrauliccylinders,alldagreatvarietyofpowertransmissioncomponents.Steeltubesarealsoemployedinthedrillstringsforoilandnaturalgasexplorationandrecovery.Steelpipesareusedinthetransportofgas,oilandotherfluids.ControlledThermal--MechanicalProcessing(CTMP)involvesprecisecontroloftemperature,mechanicaldeformation,andmicr…     

钛合金管径向精锻数值模拟分析

针对TC4钛合金管件的径向精锻,根据其工艺特点进行了简化建模,利用数值模拟软件Deform 3D对管件径向精锻过程进行了数值模拟,通过其成形过程的应力、应变分布特征,分析钛合金管的成形特点;通过坯料金属流动的速度场分布,分析该零件成形过程及特点.通过其行程--载荷曲线,进行成形力预测,对实际生产过程具有较大的意义.进行了模具受力分析,对模具寿命的预测有一定帮助.在该管件的数值模拟基础上进行了生产试制,试件产品成形顺利,质量良好.     

Cold welding sealing of copper-water micro heat pipe ends

The quality of micro heat pipe(MHP) is strongly affected by sealing technology. Based on the analysis of requirements of sealing technology, a cold welding technology was presented to seal MHP. In the cold welding process, compression force was used to flatten micro groove copper(MGC) tube. Then the bonding of MGC tube was reached because of intensively plastic deformation of MGC tube under pressure. It is found that the plastic deformation area of the cold welding of MGC tube can be divided into three sections. The deformation of micro grooves in each section was investigated; the influence of the dimensions of cylindrical heads on the weld joint shape and strength was studied; and a comparison between smooth copper tube and MGC tube was done. The results show that a groove compression stage exists in the cold welding of MGC tube besides a flattened stage and a melting stage.     

Elasto-plastic finite element analysis of squaring circular tube

The flow rule of Prandtl-Reuss was adopted and incremental elasto-plastic finite-element analysis formulation of Coulomb＇s friction law combining the finite deformation theory was established, and Lagrangian formulation for simulating the squaring process of circular tube was updated. Incremental Coulomb＇s friction law was used in the global stiffness matrix to solve the sliding-sticking state of friction at the boundary contact interface. During the squaring process, the linear factor rmin was adopted to solve the non-linear boundary problems of changing node contact and separation, elasto-plastic transient situation in an element and the non-linear constitutive behavior of material so as to make each reasonable increment of the punch meet the demand of calculation for linear increment. The squaring process of circular tube, load distribution and final shape of work piece after unloading were simulated by this mode and compared with research data. It is known that the circular tube with higher geometrical ratio （R/t） could be pressed into symmetric square tube without collapse. This result can provide reference for the analysis of this process and evaluation and improvement of product defects.     

薄壁硬质合金喇叭管烧结工艺及控制

分析了硬质合金喇叭管在真空烧结过程中变形的影响因素,结果表明,重力作用是烧结变形的主要原因,采用正确的装舟方式可以有效地减小大长径比薄壁喇叭管的弯曲变形,并提出了几种抑制变形的控制措施。