共查询到20条相似文献,搜索用时 15 毫秒
1.
为了深入了解循环闭式模锻过程中变形行为规律,改进制备工艺,为下一步工业化应用奠定基础,采用Deform-3D数值模拟软件对循环闭式模锻进行有限元分析,探讨了模锻过程中试样的温度场、应变场、速度场、应力场。结果表明:加工时,坯料上端先于下端镦粗变形,逐步充满下型腔;变形过程中,试样内部大多数部位承载三维方向压缩应力,各质点流动速度不同,流动方向各异,造成剪切塑性变形始终存在;初始道次结束后试样内部各部位应变差异很大,随着后续道次的进行,应变的分布呈均匀化趋势,累积应变不断提高;温度场模拟表明,坯料模锻后棱边和表面温升很高,坯料内部大部分区域温升较低。在400℃加工铸态AZ31镁合金的实验表明:4道次后,晶粒分布均匀,平均尺寸由约178μm细化到约19μm。 相似文献
2.
3.
循环闭式模锻制备Mg-Si合金的组织和力学性能(英文) 总被引:1,自引:0,他引:1
首先制备Mg-xSi(x=0,1.5,3.3)合金,再采用一种新的大塑性变形方法——循环闭式模锻(CCDF)在450°C进行1、3和5道次加工。通过循环闭式模锻,粗大的Mg2Si颗粒被破碎成小块并且分布更加均匀,材料的拉伸强度、伸长率和硬度得到了提高。经5道次加工后Mg-1.5%Si合金的强度和伸长率同时得到提高,拉伸强度达142 MPa,伸长率为8%。采用干滑动摩擦进一步表征材料性能。结果表明,随着Si含量和加工道次的增加,材料的耐磨性能得到了提高,加工1道次后显著提高,再继续增加道次时提高不明显。经5道次加工后,Mg-3.3%Si合金的耐磨性比纯镁的高38%。根据Archard方程和摩擦效果,耐磨性的提高归结于组织的细化和均匀化。 相似文献
4.
5.
闭式冷锻机械热力偶合有限元分析 总被引:2,自引:1,他引:1
通过对两种材料闭式冷锻机械热力偶合有限元模拟,工件的机械和热力学性能以及冲头的速度、摩擦系数等加工条件对温度在工件和模具中的分布的影响进行了研究。有限元模拟的结果表明,工件的性能对热量的产生和温度分布有决定性的影响;加工条件的变化会影响温度的高低和分布。在成形加工中由于热膨胀和冷却的影响,工件和模具中温度的变化将影响工件的成形精度。 相似文献
6.
7.
《International Journal of Machine Tool Design and Research》1984,24(3):225-240
The formation of hexagonal and square shapes by forging circular workpieces within closed-dies is a common practice particularly in the manufacture of “headed” fasteners. In this paper an upper-bound method of solution is proposed which can be used on any polygonal shape. The solution is based on observed velocity fields, and die geometry and takes into account the effect of friction on all surfaces of contact between the die and workpiece. Very close agreement was found between the predicted values of mean forging pressure and those obtained from experimental test performed on hexagonal and square shapes. 相似文献
8.
多工位高速锻造是一种节能减耗的先进成形技术,与传统的单工位多工序锻造有较大区别,不合适的预锻工位模具设计在生产中会造成载荷过大、锻件充填质量差、折叠等问题。文章提出了基于近似替代模型的多工位高速锻造预锻模具优化设计方法,采用拉丁超立方抽样方法构造初始样本点集,应用有限元软件获得响应值,并应用Kriging模型和BP神经网络模型建立真实问题的替代模型,来近似拟合预锻工位模具形状与成形载荷、成形质量之间的关系,并结合基于惩罚函数法的遗传算法求得最优解。以3工位高速锻造问题为例,经过优化取得了良好的效果,与初始设计相比,成形质量显著提高,成形载荷下降了40%左右。 相似文献
9.
机匣体多向模锻的热力耦合数值模拟 总被引:2,自引:0,他引:2
机匣体是枪械上的一个关键零件,其质量对枪械的整体性能有着非常重要的影响.机匣体的材料为LC4超硬铝合金,该合金的塑性差,变形流动阻力大,且具有速度敏感性.对机匣体锻件的结构特点及相对尺寸关系进行了分析,指出多向模锻是成形该锻件的优选工艺方案.制定了多向模锻工艺方案,设计了辊锻毛坯和多向模锻模具,并采用DEFORM-3D对终锻成形过程进行了数值模拟,分析了变形过程及温度场的变化规律.根据模拟结果进行了工艺试验,最后得到了合格的样件.证明了采用该工艺方案可以很好地保证成形温度,提高材料塑性,解决其成形困难的问题,同时也证明数值模拟的正确性. 相似文献
10.
开式模锻终锻型槽充满难度系数 总被引:3,自引:0,他引:3
根据对开式模锻变形过程的理论分析,首次提出开式模锻终锻型槽充满难度系数N的概念,用以定量描述锻件形状复杂程度和其它主要因素对锻件充满成形过程的影响,并说明了N概念的客观性、准确性及其应用。 相似文献
11.
张国杰 《锻压装备与制造技术》2013,48(2)
结合公司1250t平锻机,介绍此种设备生产锻件工艺特点,并对日常生产中遇到的杆部直线度超差、垫伤、折叠及错模等锻件缺陷进行分析并提出解决办法. 相似文献
12.
13.
14.
15.
为了解决凸轮轴热锻过程中的材料浪费和成型载荷较大的问题,基于遗传算法、克里金预测和数值模拟的动态协同技术,提出了将填充、折叠作为约束的热模锻坯料优化策略。在优化过程中,克里金模型用于构建局部区域的梯度信息,并用数值模拟对克里金模型进行动态矫正,遗传算法控制设计变量的进化方向。用凸轮轴锻件作为优化案例,并对凸轮轴锻件的形状进行分析,设计了一种坯料形状并选用其3个尺寸参数作为优化参数。优化结果表明:该方法能够优化3D成型问题,可显著减少下料体积、节省大约27.81%材料。优化后的坯料能够满足充填完整约束、无折叠约束,并且优化后的成型载荷降低了大约71.43%左右,优化后的设计变量取值为D1=40.6,D2=60,D3=16.6。 相似文献
16.
17.
M. Bakhshi-Jooybari I. Pillinger P. Hartley T.A. Dean 《International Journal of Machine Tools and Manufacture》1996,36(9):1021-1032
Close-die upsetting often forms part of the sequence of producing a finished part from a billet in closed-die precision forging. Experiments have been performed to obtain the geometry of the deformed workpiece, and also the forging load as a function of punch movement during the closed-die upsetting. An elastic-plastic finite element program has also been used to simulate the process. In order to obtain realistic results from the simulation, preliminary experiments were carried out to ensure that the thermal parameters were properly introduced. The results obtained from the simulation are in good agreement with those from the experiments. As the FE simulation has been validated by experiment it may be used alone with confidence to generate data for an intelligent knowledge-based system (IKBS) for forging die design which includes similar processes. 相似文献
18.
Quantitative data for precision, closed-die, forging: Internal deformations and computer simulations
J.N. Majerus K.P. Jen H. Gong 《International Journal of Machine Tools and Manufacture》1997,37(4):523-554
This paper presents a quantitative experimental study of the internal deformations generated during a precision closed-die (PCD), isothermal, forging. The purpose of the study is to obtain statistically meaningful data so that accuracy tests can be conducted for different forging-simulation programs. A circular bar (25.4 mm diameter) of tin/lead eutectic solder is used for the billet, and the closed-die cross-section is an ‘H’ shape. Vertical arrays of tracer particles, aligned in the longitudinal direction of the workpiece, permit the internal deformations to be measured. The initial radial locations are measured to be within the desired location with a coefficient-of-variation of only 1.96%, and the bottom location of the vertical tracer-array is controlled to be within ±0.15% of the top location. The standard deviation for all internal displacements is 0.233 mm for the radial position, 0.157 mm for the vertical position, and sources of these deviations are discussed. One set of simulations with one FEM computer model, ALPID-v2.1 for rigid-thermoviscoplastic behavior, is conducted and compared with the data. Parametric sensitivity studies are also done, and various reasons for discrepancies are discussed. One major reason appears to be that the frictional behavior changes with both surface location and reductions-in-height of the billet, contrary to the simulation's assumed constant value. Also, if no rezoning is done, ultra-small, equisized-elements appear to be required for the simulation of both the PCD forging and the upset calibration-test. 相似文献
19.