带阻尼台叶片多向模锻过程温度分布研究

在确定了模具分模形式及分模面的基础上,基于DEFORM-3D,建立了带阻尼台叶片多向模锻过程的三维热力耦合有限元模型,确定了模具的加载方式,实现了带阻尼台叶片多向模锻过程的有限元模拟。研究得到了不同压下量下坯料表层温度场及典型截面温度场,揭示了带阻尼台叶片多向模锻过程温度的分布规律。     

发动机泵体精密热模锻成形工艺研究

目的为了提高发动机泵体综合机械性能和降低制造成本,采用精密热模锻技术来实现泵体的精确成形。方法通过确定锻件分模面位置,建立了泵体精密热模锻几何实体模型;在此基础上,建立了泵体热模锻过程三维有限元模型和模拟参数,实现了精密热模锻过程有限元模拟模型。结果通过数值模拟,获得了成形过程中坯料的速度场、等效应变场和温度场及载荷-行程曲线,揭示了泵体热模锻过程中金属充填模具型腔的情况及其变形机理,获得了温度场应变分布以及载荷、打击能量随行程的变化规律,优化了预成形时拍方坯料长度等参数,为确定成形工艺参数提供了科学依据。结论经试验验证,新工艺成形的锻件非加工外形面尺寸精度达到了零件要求,数值模拟结果与实验结果一致。     

三通阀体多向模锻工艺研究

针对三通阀体结构特点和性能要求,采用多向模锻近净成形的工艺方法,利用有限元数值模拟方法得到锻件在成形过程中的网格分布、温度场、应力应变场、载荷曲线等,运用分流成形原理提出一种改进方案,有效降低了合模力,为实际生产提供了依据。     

上模压下速度对带阻尼台叶片精锻影响的研究

利用DEFORM-3D,采用刚粘塑性有限元法,建立了带阻尼台叶片精锻过程的三维有限元模型,模拟分析了上模压下速度对带阻尼台叶片精锻过程的影响规律.获得了不同上模压下速度时的等效应力、最大主应力等场变量分布及带阻尼台叶片精锻过程载荷-行程曲线,并根据最大主应力分布提出了对终锻坯料形状设计的建议.研究结果对带阻尼台叶片精锻工艺的制订具有重要的指导意义.     

车用发动机共轨管精密成形工艺与试验研究

目的为了提高柴油发动机的综合机械性能和降低制造成本,采用精密成形技术来实现共轨管的制备。方法通过工艺分析,设计了锻件形状、分模方式、飞边槽形式以及模具主要结构,建立了共轨管精密成形的有限元模型,并初步进行了主体设备选型。结果通过有限元模拟,对设计的精密成形工艺进行了仿真,获得了成形过程中坯料的速度场、等效应变分布及行程-载荷曲线,揭示了共轨管成形过程中金属在型腔中的流动情况,以及成形载荷的变化情况。结论通过最终工艺试制,验证并确定了工艺方案,根据零件的自身特点,突破了传统以投影面最大处为分模面的工艺,为最终的生产试制提供了参考依据。共轨管锻件充型饱满,5个小凸台均充型完全,尺寸均满足产品的技术要求,对后续简化工艺、提升产品的性能都有较大的作用。     

基于有限元法的轮毂成形工艺对比

目的对比某型号轮毂成形的工艺方案。方法对轮毂在不同条件下的成形过程进行了数值模拟和实验研究,分析成形工艺对应力分布、应变分布、金属流动速度场、成形载荷及内部组织的影响。结果坯料在800℃下采用闭式模锻所需成形载荷小,模具结构较简单,内部组织为粒状珠光体,力学性能优于其他2种方案下的内部组织魏氏体。结论闭塞式挤压和闭式模锻成形等效应力、等效应变、金属流动速度场、成形载荷及内部组织各不相同。模拟结果可以指导实际生产中工艺方案的选择。     

多向挤压模具及三通件的成形流动分析

利用有限元分析软件Msc Marc来模拟三通阀体零件多向主动加载成形过程.通过对多向同步加载、多向分步加载、多向顺序加载等3种不同成形方式的金属流线,以及加载过程中挤压力曲线的比较,得出了多向分步加载时挤压力曲线平滑,对模具损伤较小,而且不会出现金属折叠,为最佳的加载工艺方案.详细论述了多向分步加载时金属的流动规律,即首先向右方向的凸模1与凹模间的间隙流入,随后才向凸模2与凹模间半圆柱形凸起的空腔流入.     

浮动凹模温精密成形圆柱斜齿轮变形规律分析

目的研究采用浮动凹模工艺温精密成形圆柱斜齿轮时,不同凹模运动速度下齿轮力能参数和各种场量变化规律。方法结合浮动凹模原理和圆柱斜齿轮结构特点,利用Defrom-3D软件建立变形-传热耦合有限元模型,模拟圆柱斜齿轮采用浮动凹模温精密成形过程,分析不同凹模运动速度下的变形规律。结果通过模拟分析,得到了凹模运动速度不同时的温成形斜齿轮成形载荷特点、坯料流动速度场分布、等效应力-应变分布、温度场分布等规律。结论采用浮动凹模工艺成形圆柱斜齿轮,可以减小成形力,当凹模运动速度大于凸模下行速度时,齿轮成形性更好。     

多向模锻的模具结构和设计

讨论多向模锻的模具结构水平分模模具结构、垂直分模模具结构、联合分模模具结构和特殊模具结构,在此基础上,又讨论多向模锻模具的型腔位置、导向装置、凹模导向、深孔锻件凹模、冲头、推杆等设计的要点以及模具材料的选用.     

基于有限元模拟的四通阀体多向模锻工艺研究

针对阀体传统制造工艺效率低、锻件性能差、成本高等问题,本文提出采用先进的多向模锻工艺进行阀体制造,并以一种不等径四通阀体为典型对象,结合Deform-3D数值分析进行工艺研究.首先,根据不等径四通阀体的结构特征,确定了分模面,并依此设计了两种锻件图;其次,根据锻件图设计了 3种不同的多向模锻结构,并分别确定了模具的加载...     

钛合金多向锻造数值模拟

目的研究TC4钛合金在多向锻造过程中的变形行为。方法基于Deform-3D模拟软件平台,对钛合金的多向锻造变形过程进行有限元模拟分析,研究不同工艺参数(锻造温度、锻造速度、锻造工步)下合金最大主应力、等效应变和载荷最大值的变化规律。结果多向锻造的每工步锻造为典型的镦粗过程,坯料中心部位一直受压应力作用,鼓肚处则出现最大拉应力。随着锻造温度的升高和锻造速度的减小,最大压应力和拉应力均减小,多工步锻造之后合金主应力场分布更加均匀。随着锻造工步的增加,坯料等效应变增大且中心大变形区域体积分数增加。最大载荷随锻造温度的升高和锻造速度的降低而减小,相同参数下不同锻造工步的载荷最大值变化不大。结论锻造温度、锻造速度、锻造工步对TC4钛合金多向锻造变形行为有显著的影响,适当选择多向锻造工艺参数,可以降低载荷并获得均匀性较好的坯料。     

星形套冷态闭塞式精锻成形分析

目的提出星形套冷精锻成形工艺优化方案,提高模具使用寿命,对生产操作进行规范。方法分析零件结构,确定了合理的分模面;运用数值模拟方法,选取不同的冲头进给速度和冲头形状,对星形套冷精锻成形过程进行了模拟分析。结果获得了冷精锻成形过程中冲头进给速度和冲头形状对温度场、应力场、金属速度场、工作载荷和模具寿命的影响。结论通过分析冲头进给速度和冲头形状对星形套成形的影响,并对其进行控制和优化,得出了最优工艺参数区间,为实际生产提供了参考依据和理论指导。     

支承架数值模拟应用

利用Pro/e对毛坯、模具进行三维造型,利用模拟软件DEFORM-3D对支承架等温锻造成形过程进行数值模拟,得到成形过程中锻件的填充情况以及成形载荷、应变场和应力场的场量分布。通过对比实际零件生产情况再次证明了该软件模拟的可行性及有效性。基于模拟结果,对锻造缺陷的成因进行了初步分析,并提出了成形工艺及模具设计的改进建议。     

Effect of processing parameters on shear bands in non-isothermal hot forging of Ti -6Al -4V

Abstract

The alloy system Ti- 6Al- 4V is the prominent Ti alloy system for aerospace and biomedical applications, as a result of its mechanical property balance and biocompatibility. Since the mechanical characterisation of Ti- 6Al- 4V is strongly sensitive to processing parameters there is relationship between processing variables, i.e. strain rate and temperature, microstructure, and properties under different loading conditions. Two phase (α + β) titanium alloys undergo flow instabilities and are susceptible to shear bands or regions of localised deformation crossing many grains during hot forging under non-isothermal conditions (dies and workpiece at different temperatures). Under such conditions shear bands can be generated even in materials without flow softening attributes. This occurs if the forging parameters lead to large amounts of heat transfer between the dies and the workpiece. This study investigates the occurrence of shear bands during non-isothermal, hot forging of Ti -6Al- 4V in order to evaluate the process parameters that generally lead to shear bands in conventional hot forging of metals. Upset compression tests on cylindrical specimens were conducted in a mechanical press and lateral side pressing tests on long, round bars were performed in either a mechanical press or a hydraulic press. The tests ranged from axisymmetric to plane strain compression. In upset specimens shear bands occurred at an angle of 45° to the compression axis and bands of intense deformation separated chill zones from the deforming bulk. Observation also demonstrated that the fracture might be owing to microvoids nucleated at weak points in sections of the shear surfaces. For plane strain deformation, shear bands were found to initiate along zero extension directions in a manner analogous to the formation and propagation of shear bands in isothermal hot forging. Although the shear band features at hot forging temperatures were similar to each other, there was a difference in the hardness and thickness of the shear bands depending on deformation mode, amount, and temperature.     

Effects of Process Parameters on the Temperature Field in Ti-6Al-4V Alloy Blade Precision Forging Process

Blade precision forging is a high temperature and large plastic deformation process. Process parameters have a great effect on temperature distribution in billet, so in this paper, by taking a Ti-6Al-4V alloy blade with a tenon as an object, the influence of process parameters on the temperature distribution in precision forging process was investigated using 3D coupled thermo-mechanical FEM （finite element method） code developed by the authors. The results obtained illustrate that： （1） the gradient of temperature distribution increases with increasing the deformation degree; （2） with increasing the initial temperature of the billet, the zones of high temperature become larger, and the gradient of temperature distribution hardly has any increase; （3） friction factors have little effect on the distribution of temperature field; （4） with increasing upper die velocity, temperature of the billet increases while the temperature gradient in billet decreases. The results are helpful to the design and optimization of the process parameters in precision forging process of Ti-alloy blade.     

Effects of Process Parameters on the Temperature Field in Ti-6A1-4V Alloy Blade Precision Forging Process

Blade precision forging is a high temperature and large plastic deformation process. Process parameters have a great effect on temperature distribution in billet, so in this paper, by taking a Ti-6Al-4V alloy blade with a tenon as an object, the influence of process parameters on the temperature distribution in precision forging process was investigated using 3D coupled thermo-mechanical FEM (finite element method) code developed by the authors. The results obtained illustrate that: (1) the gradient of temperature distribution increases with increasing the deformation degree; (2) with increasing the initial temperature of the billet, the zones of high temperature become larger, and the gradient of temperature distribution hardly has any increase; (3)friction factors have little effect on the distribution of temperature field; (4) with increasing upper die velocity,temperature of the billet increases while the temperature gradient in billet decreases. The results are helpful to the design and optimization of the process parameters in precision forging process of Ti-alloy blade.