DN2000特大型管模成形仿真分析与试验研究

针对DN2000特大管模锻件相对壁厚薄、拔长效率低的问题,通过建立有限元分析模型,分析了试制工装生产可行性及对拔长效率的影响,对锻件进行坯料与芯轴贴合情况、拔长时长度增加及成形载荷进行模拟分析。结果表明:采用上平下V砧能够满足该管模锻造拔长生产,拔长效率较高。通过生产试制,验证了上述分析的正确性和可行性。     

DN1800整锻管模拔长及空收成形技术北大核心CSCD

DN1800特大整锻管模锻件相对壁厚极小、规格大、吨位重、火次多、拔长效率低、技术要求高,且现有生产工装辅具不匹配,在工艺设计、质量控制和生产组织方面难度极大。通过研究锻造拔长机理及过程,提出控拔控压工艺方案、拔长效率提升控制方案和Φ1900 mm芯轴拔长+上平下V形砧空收+Φ2200 mm上圆弧下V形砧复合空收成形工艺方案,并结合工艺性分析,建立了塑性变形有限元分析模型,不断优化工艺参数,通过提出生产操作关键点,细化空收工艺参数,严格进砧量、压下量、温度和旋转角度的匹配控制,成功完成特大整锻管模的试制生产,验证了工艺参数及成形工艺的合理性,积累了特大整锻管模特殊锻造成形经验。     

管模工艺的优化

管模是生产离心球墨铸铁管的模具,其毛坯的锻造成型非常困难。本文介绍了管模锻造工艺的优化过程。采用优化后的工艺,解决了管模在锻造生产中出现的各种问题,使管模的成品率大幅提高。同时也为长筒型锻件的成型提供了可靠的参考依据。     

平砧拔长过程中坯料的展宽规律及计算机程序控制

本文研究了水压机平砧拔长大型锻件过程中坯料的展宽规律,根据模拟实验得出了理论计算公式,并用计算机编制了《钢坯拔长程序手册》,使钢锭拔长工艺过程得以控制。研究结果经三年多生产性应用表明,在提高锻造效率、准确控制锻件外形尺寸、保证内部变形压实效果、提高锻件质量和最终产品合格率方面,收到较显著的经济效益。对自由锻造工艺编制工作和生产自动化管理也具有重要意义。     

大型SA-336F12贮水箱筒体锻件锻造工艺研究

介绍了长度尺寸超过芯轴有效长度尺寸的长筒体锻件的锻造方法。通过先拔长芯轴端头部,拔至锻件图尺寸后,再逐步往里拔长的方法,可以实现锻件的锻造成型。     

轴类件拔长V型砧和四砧径向锻造锻透性研究

轴类大锻件拔长可以采用V型砧、四砧径向锻造等。为了解这些拔长方式对锻件芯部变形的影响,应用有限元软件Super Form模拟了拔长锻造过程,对比分析了V型砧和四砧径向锻造两种工艺方法的锻透性。研究表明:V型砧拔长,锻后锻件内部等效应变分布不均匀,各处变形差异较大,经3道次拔长后,锻件芯部锻透性较好,给定条件下的累积等效应变约为1.6;四砧径向锻造,锻后锻件内部等效应变分布比较均匀,但锻件芯部锻透性较差,给定条件下芯部等效应变小于0.2,且端部一定长度范围内,芯部等效应变更小,经4道次拔长后,芯部累积等效应变为0.8左右。     

水平V型锥面砧改善轴类锻件异向性的研究

水平V型锥面砧为横向性能有要求的轴类锻件提供了一种拔长锻造方法,通过改变工具形状、控制纤维流向的方法,来提高轴类锻件横向力学性能,改善异向性.本文进行了水平V型锥面砧与上平砧-下V砧拔长矩形截面坯料锻造的对比试验,通过对比两种锻造方法拔长锻件的纵向、横向力学性能,证实了水平V型锥面砧锻造法达到了普通锻造方法难以实现的锻造效果--轴类锻件力学性能的异向性明显改善,即水平V型锥面砧拔长的锻件同部位屈服强度、抗拉强度和延伸率的横向与纵向之比均在1.0附近变化.     

大型挤压辊锻件两次镦拔工艺锻前加热研究

采用两次镦拔锻造工艺,可以在大型水压机上利用小钢锭锻造大型挤压辊锻件.由于锻件尺寸大,两次镦粗和两次拔长相结合,锻造过程历时较长,需要三次锻前加热.加热不当会造成资源和时间的浪费,甚至造成锻件的报废.本文通过理论分析,考虑到材质和锻件尺寸及生产条件,制定了RP170-110挤压辊锻件两次镦拔锻造前的加热工艺,包括锻造温度范围、装炉温度、加热速度以及保温时间等.结果表明,该加热工艺具有良好效果.     

5CrNiMo热作模具钢模块锻造方法的数值模拟

为保证曲轴模块锻件具有良好的机械性能,常采用平砧对钢锭进行镦粗、拔长、再镦粗、再拔长等多工序方式成形。本文以5CrNiMo热作模具钢曲轴模块锻件为对象,利用有限元软件Deform-3D、对其在8t电液锤上采用轴向反复镦拔法、径向十字锻造法和综合锻造法等3种不同的锻造方法进行镦粗、拔长、再镦粗、再拔长的全过程进行了数值模拟,分析了3种不同锻造方法锻造后的温度场、应力场和锻造力分布规律。结果表明,采用径向十字锻造法时,其温度场和应力场分布均匀,锻造力较小,锻造过程不易产生裂纹,且锻造操作方法不复杂,为5CrNiMo曲轴模块锻件最合适锻造方法。     

不同锻造比对2A50铝合金组织和性能的影响

影响铝合金自由锻件组织和性能的因素很多,铸锭质量、锻造变形程度和热处理工艺影响最大。通过对2A50铝合金不同锻造工艺对性能产生的影响进行研究,采用不同的锻造方案(镦粗、多方锻、拔长等)和不同的锻造比生产的锻件进行性能分析,阐明了自由锻造工艺对锻件性能的影响。     

Special-shaped tube drawing forming and conformal optimization of die cavity

Aiming at the issues in quick processing and modeling design of drawing special-shaped tube die, by Conformal Mapping Theory and the numerical trigonometry method of interpolation between odd points and even points, the conformal mapping function is obtained. As the result, three-dimension drawing forming were converted into that of two-dimension problems, and the plastic stream function was analyzed, die cavity modeling and its optimized function were set up. Combining with modern processing technology, NC program and CAM of die cavity can be realized. Taking the drawing forming of hexagon tube with arc radii r and ellipse-shaped tube as instances, the drawing die cavity optimization of special-shaped tube was achieved, as well as, the changing principle of wall thickness was analyzed.     

Effect of frictions on cross section quality of thin-walled tube NC bending

1 Introduction Thin-walled tube bending parts have been increasingly used in many industry fields such as aviation, aerospace and automobile for their easy satisfaction in light weight, high strength and low consuming. The numerical controlled(NC) rotar…     

A conical mandrel tube drawing test designed to assess failure criteria

Cold tube drawing is a metal forming process which enables to produce tubes with high dimensional precision. It consists in reducing tube dimensions by pulling it through a die. Tube outer diameter is calibrated by a die and the tube inner diameter and thickness are calibrated by a mandrel. One of the major concern of metal forming industry is the constant improvement of productivity and product quality. In the aim of pushing the process to the limit the question is how far the material can be processed without occurrence of failure. In the present study, a long conical mandrel with a small cone angle was designed in order to carry out drawing tests up to fracture with experimental conditions very close to the industrial process. The FEM of the process was built in order to access the local stress and strain data. A specific emphasis was put on the friction characterisation. For that purpose force measurement during the conical mandrel experiments enabled to characterise a pressure dependent friction coefficient constitutive law by means of an inverse analysis. Finally, eleven failure criteria were selected to study the drawability of cobalt–chromium alloy tubes. The assessment of failure criteria based on damage variables or damage accumulation variables involved their calibration on uniaxial tensile tests. The experimental studies were completed by SEM fractography which enabled to understand the fracture locus and the propagation direction of the fracture.     

管帽零件多工位级进模设计

为了批量生产管帽零件,结合零件的结构特点、精度要求和冲压工艺性,进行了零件的多工位级进模排样设计.因管帽零件较小,为了增加模具强度、便于零件布置,在零件的第2工位设计了空工位,冲零件内孔时需与外圆同心.管帽零件侧壁较薄,需要合理设计拉深高度和拉深次数,以保证零件的精度.条料经过定位块后,继续往右运动,经过侧刃切边,侧刃...     

管坯镦粗工艺

管坯成形过程容易失稳，产生折纹；同时因管壁厚度公差大，坯料体积不易控制，使得锻件成形困难，质量难以控制。本针对我厂生产的一种管坯锻件的成形工艺，结合有限元模拟与实际生产情况，着重分析了第一道聚集工步的特点，型腔设计的基本原则，并对一些工艺参数进行了探讨。     

G52管帽多工位级进模设计

根据G52管帽零件冲压工艺特点,对模具总体结构和中孔翻孔、翻斜孔、拉深壳体等关键工序进行了优化组合,设计了多工位级进模。生产实践证明:模具结构合理,制件质量稳定,可满足企业生产要求。     

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.     

基于LS-DYNA有限元平台的带反拉力空拔管性能

带反拉力空拔管具有提高产品质量和简化工艺过程等特点,在冷拔行业中得到广泛应用。文章应用LS-DYNA有限元平台数值模拟带反拉力空拔管全过程,得到各场量的动态分布情况,从而分析了拔制中产生横裂等缺陷的机理和壁厚变化规律;探讨了工艺参数,即模锥角、摩擦系数、反拉力与摩擦阻力之间的影响关系。研究结果为冷拔工艺设计和优化模具结构提供了理论依据。     

基于Deform的三缸曲轴锻模设计

在分析了42CrMo钢三缸曲轴结构特征的基础上,采用Deform软件,优化了预锻件敷料结构,敷料轮廓由直线相交转变为圆弧过渡,并将夹角由15°优化为20°,降低了模膛应力值;设计了便于变形、分模以及后续配重的余块结构,并在预锻模边缘设计了半开半闭式挤压筒结构,分配了预、终锻变形量,得到了预、终锻模具结构.利用Defor...     

工艺参数对薄壁铜管游动芯头振动拉拔过程拉拔力影响分析

在金属塑性成形中加入振动,可以有效降低材料变形抗力并提高产品质量。以薄壁铜管游动芯头拉拔为研究对象,分析了振动对铜管拉拔过程中拉拔力的影响,并通过有限元分析软件MARC,对不同的工艺参数(拉拔速度、外模模角和芯头锥角)进行数值模拟。研究结果表明:针对本模型,存在一个最佳外模半锥角和芯头锥角组合(外模半锥角α为12°,芯头锥角β为9°),使得薄壁铜管游动芯头振动拉拔过程中的拉拔力最小,而拉拔速度对拉拔力的影响较小。