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。     

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。     

张力减径管增厚段壁厚分布数学模型

通过对张减管增厚段壁厚分布形态的测量和分析,给出了较有实用价值的数学解析式。     

张力减径壁厚系数γ辨析

解析了张力减径壁厚系数γ=S/D和γ-2S/D的物理意义及应用条件,给出了平均壁厚系数表达式。     

钢管微张力减径增壁量的试验与探讨

钢管在减径过程中,减径量一定时,影响其增壁量的主要因素是钢管的轧制温度和张力系数等。就生产中出现的钢管实际增壁量大于设计值的问题,采用不同的轧制工艺进行了试验,探讨了轧制工艺与钢管增壁量之间的关系。     

集中差速传动张力减径机各道次壁厚的计算

提出了集中差速传动张力减径机各道次钢管壁厚变化的计算方法,对照分析了理论计算与实际应用的统一性,分析表明,该计算方法实用可靠。     

钢管张力减径过程的有限元模拟

根据钢管张力减径过程的变形特点,对五机架张力减径过程进行系统建模,利用MARC软件进行三维弹塑性有限元分析,得出了钢管在各机架的变形情况,为预报产品质量、分析产品缺陷提供了依据。     

12架微张力减径机壁厚变化数学模型的研究

在12架三辊式微张力减径机上,实测了增壁率、减径率、壁厚系数、减径温度、减径速度、张力等主要参数,分析研究了这些参数对生产典型品种无缝钢管壁厚精度的影响程度,通过计算机回归处理得出壁厚不均数学模型公式,经现场实践证明该数学模型是有效的。     

微张力减径的钢管质量及其控制

介绍了衡阳钢管厂φ108mm三辊轧管机组配置12架微张力减径机生产中厚壁钢管的外径精度、壁厚精度及内外表面质量情况。实践证明采用合理的减径工艺制度,用一组微张力减径机代替二辊减径机+回转定径机生产中厚壁钢管是极为成功的。     

无缝钢管张力减径过程的有限元分析

根据张力减径机组轧制工艺,采用非线性有限元法建立了三维热力耦合弹塑性有限元模型,运用该模型对实际张力减径过程进行了数值模拟,得到了管坯的温度场、应变场和应力场分布规律,分析了管坯经过各机架时的壁厚变化。模拟得到的轧制力能参数与现场实测结果吻合较好,为张力减径过程的工艺理论研究提供了依据。     

钢管冷斜轧工艺与试验研究

针对传统钢管冷轧(拔)生产方式存在的问题和钢管深加工的需要,根据斜轧过程中轧件运动和金属变形的特点,探索了钢管冷斜轧成型的必要条件,并采用刚塑性有限元方法,计算其变形过程的速度场、应变和应力,设计符合钢管冷斜轧特点的轧辊辊型。通过理论分析和工业性试验,证明了该工艺的可行性和实用性。该工艺能够部分替代钢管冷轧冷拔工艺,也可用于双金属管材的复合加工。     

俄罗斯钢管业的现状及前景分析

介绍了俄罗斯钢管生产近期概况,主要钢管企业在提高市场竞争力方面进行的技术改造和新产品开发的一些动态,俄罗斯钢管进出口情况和复苏俄罗斯钢管生产的应对措施。     

DEMAG钢管水压试验机的工作原理及其故障分析

以上海宝钢集团公司钢管分公司钢管管体3号水压试验机为例 ,介绍了DEMAG水压机的工作原理 ,并就其综合故障进行了剖析 ,进而提出了解决的方案     

HTP与TMCP工艺X80钢级板材制管性能的对比分析

通过对低碳高铌不添加钼的Cr-Nb微合金钢高温轧制(HTP)、低碳Mo-Nb微合金化钢传统热机械轧制(TMCP)的两种钢板制管性能的对比分析,证实了采用HTP工艺技术生产的管线钢板完全能够制造出符合现行技术标准要求的X80钢级直缝埋弧焊管,而且生产成本大幅度降低,有助于提升管线管的竞争力。     

提高钢管磁化系统检测速度的有限元分析

ISO标准规定的钢管检测系统检测速度低,难以满足实际生产要求。有限元分析软件ANSYS作为一种很有用的工具软件,能对磁场进行方便、高效的分析。将ANSYS引入钢管磁化系统分析,通过仿真试验来改进检测设备的磁化设计,建立磁场模型。该磁化系统能使钢管检测速度提高,信噪比增大。     

钢管表面高压水除鳞效果分析与对策

介绍了钢管表面高压水除鳞系统的工作原理;分析了影响钢管表面高压水除鳞效果的设备问题;探讨了钢管表面生红锈的化学机理。通过改进高压单向截止阀设计和曲轴进油口的密封形式,并通过实验对比选择小直径喷嘴解决了钢管表面生红锈的问题,并在保证钢管表面不生红锈的同时取得了良好的除鳞效果。     

Experimental and finite element simulation study of the adiabatic shear band phenomenon in cold heading process

This paper presents the outcomes of a comprehensive experimental, metallurgical and finite element (FE) simulation study to characterize the development of adiabatic shear band (ASB) phenomenon in steel cold heading (CH) process. The main objective of this work is to investigate the complex interplay of different process and material parameters on the ASB development stages inside the cold headed parts.In this work, the drop weight compression test (DWCT) was selected to simulate the CH process impact loads on specimens machined from 1038 steel and 1018 steel. Series of DWCTs were performed under different impact loading conditions. The goal of these tests is to achieve different deformation levels and introduce ASBs at different stages.To reach a full understanding of this complex phenomenon, the FE simulation analysis was used to support the metallurgical examination of the DWCT specimens. The FE analysis provided important details about the changes of different material and process parameters at the critical zones inside the ASBs.This study confirmed that the ASB is mainly a thermo-mechanically controlled phenomenon. The ASBs develop in three stages: homogeneous plastic strain, inhomogeneous plastic strain, and strain localization. The ASB development stage depends mainly on the status of the competition between the work hardening and the thermal and geometrical softening mechanisms inside the bands. The domination of the softening mechanisms at advanced levels of deformation triggers a self-catalytic strain localization and material strength degradation process that leads to failure inside the band.In general, the metallurgical and finite element analysis investigation revealed that under impact loads, three ASBs can develop simultaneously inside the cold headed parts; lower, upper and central ASBs. As the deformation continues; the development of the lower and upper bands slows down and contributes in the rapid development of the adjacent central ASB. This study confirmed that the ASB has a canonical structure which leads to an ASB that can experience different development stages along the same band simultaneously.This study proved that the shape and the type of ASBs in cold headed parts depend highly on material's properties. The metallurgical and finite element analysis revealed that the higher the strength of the tested steel, the easier to form a narrow ASB that reaches the localization stage at low deformation levels. In contrast, ductile steels experience wider ASBs when subjected to the same deformation levels. These bands require higher levels of deformation to reach the localization stage in comparison to higher strength steels.     

Experimental and finite element analysis of temperature and energy partition to the workpiece while grinding with a flexible robot

Grinding processes performed with flexible robotic tool holders are very unlike conventional types of grinding because of low stiffness of the robot's structure. A special flexible robotic grinding process is used for in situ maintenance of large hydroelectric equipment for bulk material removal over large areas rather than as a finishing step, as is the case for most conventional grindings. Due to the low structural stiffness of tool holder, cutting is interrupted at each revolution of wheel during the grinding process. In this study, an investigation is carried out to determine the temperatures and energy partition to the workpiece for the above-mentioned flexible robotic grinding process by a three-dimensional finite element thermal model. Experiments were undertaken using embedded thermocouples to obtain the subsurface temperature at several points in the workpiece during the process. Then, energy partition to the workpiece was evaluated using a temperature-matching method between the experimental and numerical results. This ratio is used for predicting the temperature field at the wheel–workpiece interface with a relevant heat source function. Kinematics of cut and the flexible robot's dynamic behavior are considered in applying the heat input to the model. The energy partition to the workpiece in this specific flexible grinding process is found to be lower than for analogous conventional precision grinding processes. Two models, one from the literature and one from the power model of the process, are modified and proposed for determining the energy partition. The results showed that the energy partition ratio decreases by increasing the process power. Also, this ratio slightly decreases at higher feed speeds. In addition, lower temperatures were seen at higher powers due to the lower intensity of heat input over a larger contact area. Experimental observations show close agreement between simulated contact temperatures and measured results.     

半挂车用空气弹簧弹性特性分析

利用有限元软件和实验方法对空气弹簧的弹性特性进行研究.在前处理软件Hypermesh建立空气弹簧的模型并对其进行网格划分,采用Abaqus/Standard模块对空气弹簧载荷-位移特性进行仿真计算,并利用台架试验测试空气弹簧的弹性特性.结果表明:空气弹簧具有变刚度特性,能有效提高车辆的行驶平顺性;两种方法结果基本一致,验证了有限元分析模型的正确性,为该类型空气弹簧的设计开发提供了可靠的理论依据.     

Tool design in a multi-stage drawing and ironing process of a rectangular cup with a large aspect ratio using finite element analysis

Tool design is carried out for a multi-stage deep drawing and ironing process of a rectangular cup with the large aspect ratio using the result of the finite element analysis. The analysis incorporates three-dimensional continuum elements for an elasto-plastic finite element method with the explicit time integration scheme using LS-DYNA3D. The analysis simulates the five-stage deep drawing and ironing process with the thickness control of the cup wall. Simulation is performed in order to investigate the failure by tearing during the forming process at the initial state of tool design. The analysis reveals that the difference of the drawing ratio within the cross section induces non-uniform metal flow which causes severe local extension. The irregular contact condition between the blank and the die also induces non-uniform metal flow which causes local wrinkling. This paper identifies such unfavorable mechanism in the rectangular cup drawing with ironing and proposes a new tool design with the guideline for modification in the design of the process and the sequential tool shape. The finite element analysis result with the improved tool design confirms that the proposed design not only reduces the possibility of failure but also improves the quality of a deep-drawn product. The numerical result shows fair coincidence with the experimental result.