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气门挤压成型过程的数值模拟 总被引:2,自引:0,他引:2
在非稳态分析的基础上,对2种不同尺寸的气门,运用有限元软件对其挤压成形过程进行数值模拟分析.研究表明,挤压大尺寸的气门(具有较大的β值和Rc值)需要较大的挤压力.挤压小尺寸的气门所需挤压力较小,但β值过小时坯料挤压开始变形大,凹模所受应力也较大,对挤压模凹表面的磨损加剧,缩短模具寿命.所得结论对气门成形工艺极其结构参数的优化设计具有一定的参考价值. 相似文献
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针对外星轮热挤压过程模具负载大、填充性能波动的问题,
对关键的模具结构参数(入口斜度,根部圆角,模口圆角)及核心工艺参数(挤压速度,摩擦因数,坯料初始温度,模具预热温度,模具硬度)开展联合优化,以期获得负载和填充性能的平衡。首先应用部分析因试验设计,针对最大成形载荷和填充能力进行主参数效应筛选,对得到的关键因子进行拉丁超立方抽样并对样本点进行有限元模拟。以关键因子为变量、有限元模拟结果为响应,分别建立最大成形载荷和填充能力的径向基函数近似模型。基于上述近似模型,采用线性加权和法将所得近似模型转化为单目标函数,利用粒子群算法进行全局寻优,得到优化的关键结构和工艺参数组合,并通过仿真和生产试验验证了优化结果的正确性。 相似文献
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基于冷锻数值模拟技术的圆锥滚子预应力组合凹模研究 总被引:2,自引:0,他引:2
采用弹塑性有限元模型分析软件DEFROM -3D对冷态下Gr15钢材毛坯在组合凹模中的应力应变分布进行冷锻成形模拟,得到了组合凹模各层在真实径向接触压力作用下的应力、应变、金属流动等物理参数在冷锻过程中的变化规律及凹模内侧壁接触应力沿高度方向的分布状态.模拟结果可以正确描述模具的真实应力应变状况,为较全面、准确的掌握模具的应力集中、切向应变、径向应变及其优化设计和疲劳寿命分析提供理论指导. 相似文献
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以带六边形通孔的直齿轮为例,通过有限元仿真软件DEFORM-3D对直齿轮冷精锻的几种浮动凹模工艺进行数值模拟,分析了浮动凹模工艺(凹模和上凸模以相同的速度下行)、浮动凹模配合轴分流工艺和浮动凹模预锻+浮动凹模轴分流终锻两步成形三种工艺的充填情况和载荷大小。研究结果表明,采用浮动凹模工艺锻件的充填情况较好,但是成形载荷较大;采用浮动凹模配合轴分流工艺,不仅齿形充填效果较好,而且能有效地降低成形载荷;采用浮动凹模预锻+浮动凹模轴分流终锻工艺的齿形充填效果较好,能显著地降低成形载荷。 相似文献
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基于Deform-3D对梭床的冷挤压成形过程进行数值模拟。通过正交试验的极差法和方差法,以最大成形载荷和凸模磨损量为目标变量,分析凸模材料硬度、挤压速度和润滑系数等关键参数的影响,从而获得最优工艺参数组合方案:凸模材料硬度为65HRC、润滑系数为0.1、挤压速度为30mm/s。利用最优工艺参数进行二次数值模拟,并对比了优化前后的最大成形载荷和凸模磨损量,以达到冷挤压最优效果,并通过折叠角和损伤因子分析得出满足此锻件的冷挤压成形要求,为实际的锻造生产过程提供理论指导。 相似文献
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以汽车转向螺杆类杯-杆件的温挤压凹模为例进行模具磨损分析及其寿命预测。以影响温挤压凹模磨损的4个主要因素,即凹模入口处圆角大小、模具初始硬度、模具初始温度、摩擦因子作为工艺参数,并分别选取4个不同水平值,确定四因素四水平的32组温挤压凹模磨损试验方案,通过Deform 3D有限元数值模拟软件进行成形过程的数值模拟。以不同影响因素和对应模具的磨损量为样本训练BP神经网络,建立4个主要因素与凹模磨损量之间的映射关系,以温挤压凹模磨损量为目标函数,通过遗传算法对4个影响因素进行组合优化,使凹模磨损量最小、寿命最长。 相似文献
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基于多目标优化的扁挤压筒结构设计 总被引:4,自引:1,他引:4
在组合式扁挤压筒的结构尺寸设计中,为确保挤压筒最佳工作性能的同时,最大程度地减少过盈装配后内腔产生的变形,提出了多目标优化的概念。结合有限元模拟技术和BP神经网络方法,建立了变过盈量下三层组合式扁挤压筒结构尺寸与各层等效应力分布、内腔位移之间的非线性映射模型,采用多目标遗传算法对其进行优化。优化时,采用了向量评价法、最佳个体保存策略和小生境技术,得到了均匀分布的Pareto最优解,根据定义的满意度函数,选出了最终的满意解。结果表明,在该满意解下,扁挤压筒既实现了等强度设计,又保证了内腔的尺寸精度。 相似文献
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多腔壁板铝型材挤压过程数值模拟及模具优化 总被引:6,自引:2,他引:6
挤压模具在铝型材挤压生产中起着至关重要的作用,挤压模具设计的优劣直接影响挤压产品的质量。然而实际生产中,挤压模具的设计更多依赖传统设计经验,需要多次试模和修模,无法满足产品开发需求。以典型的多腔壁板铝型材为例,应用UG建立分流组合模几何模型,采用基于任意拉格朗日—欧拉(Arbitrary Largrang-Euler,ALE)算法的HyperXtrude软件对多腔壁板铝型材的挤压成形过程进行数值模拟,获得挤压过程中速度场、温度场、应力场及金属流动情况。针对初始模具设计的不足,提出多腔壁板铝型材挤压模具优化三步曲(开设引流槽、增设阻流块、优化工作带),有效地解决了初始模具设计中速度分布不均的问题。利用数值模拟方法可以优化模具结构,提出的多腔壁板铝型材挤压模具优化三步曲对同类铝型材挤压模具结构设计具有一定的指导意义。 相似文献
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挤压模具型腔的等磨损优化设计 总被引:1,自引:0,他引:1
针对目前国内挤压模具寿命过低的情况,将有限元分析、神经网络和遗传算法结合起来应用到挤压模具型腔优化设计中。采用B样条函数插值描述凹模型腔轮廓形状,用有限元数值模拟获得型腔表面节点的应力场、速度场和温度场,基于修正Archard磨损模型计算型腔磨损深度,以此作为样本训练BP神经网络,建立模具型腔控制点与磨损深度之间的映射关系,再结合遗传算法以等磨损为目标,优化模具型腔轮廓形状。优化结果与序列二次规划法一致,可以降低模具磨损,提高模具寿命,结果与实际情况吻合,表明了这种设计方法是可行的。 相似文献
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Effects of extrusion variables on temperature distribution in axisymmetric extrusion process 总被引:2,自引:0,他引:2
A numerical method was developed to simulate the non-steady-state temperature distributions during forward extrusion process. The velocity, strain rates, and strain fields within the deformation zones during extrusion were obtained, using upper bound method of analysis to obtain internal heat generations coupled to the necessary heat transfer conduction equations. The computer program written in C++ language essentially simulates the extrusion process and takes into account extrusion variables such as material properties, friction conditions, extrusion velocity, extrusion ratio, die preheat temperature, billet height, percentage reduction in area, and die land length. The effects of billet height and percentage reduction in area on the temperature distributions within the dead metal zone give good agreements with experimental results. It is found that the higher the billet's heights and higher the percentages reduction in areas, the higher the temperature rises during the extrusion process. The die land zone shows increasing temperature rise with increasing friction coefficient, while increasing friction coefficient has no effect on the dead zone temperature. Also, increasing speed of deformation shows an increasing dead zone temperature rise than a more gradual die land temperature rise. It can be stated that the extrusion temperature increases proportionally to the increase of the container temperature. 相似文献
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The effect of billets extruded by a curved and flat-face die on the semisolid characteristics and tensile properties of thixoformed products 总被引:1,自引:1,他引:0
Amir Bolouri Yong Phil Jeon Chung Gil Kang 《The International Journal of Advanced Manufacturing Technology》2014,70(9-12):2139-2149
In this study, A356 aluminum billets in different extruded states are used as feedstock for the thixoforming. The extrusion billets were fabricated by a hot extrusion process through a flat-face and a curved die. After the induction reheating of the extrusion billets into a semisolid state, the microstructural evolution was thoroughly investigated. For the extrusion alloy by the flat-face die, there was a large variation in the average grain size (20 %) and the mean roundness (17 %) of equiaxed α-Al grains. This, together with evidence of elongated grains in the interior regions of the billet, indicated that a noticeably nonuniform globular microstructure had been obtained. In contrast, for the extrusion alloy through the curved die, the obtained globular microstructure was more uniform. There were slight variations of 5 % and 7 % in the average grain size and the mean roundness, respectively. By using the extrusion billets, some parts fabricated via the thixoforming process those underwent T6 heat treatment. The tensile test results for the fabricated parts showed that when the extrusion billet through the conventional flat-face die was used as the feedstock, there was a large scattering in the tensile properties throughout the part. In contrast, when the extruded billet through the curved die was used as the feedstock, limited variation was observed in the tensile properties. 相似文献
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A numerical method was developed to simulate the transient temperature distributions during forward extrusion process. The
computer program simulates the extrusion process and takes into account some extrusion variables such as extrusion velocity,
extrusion ratio, die preheat temperature, and percentage reduction in area. It can be seen that the higher the percentages
reduction in areas, the higher the temperature rises during the extrusion process. Also, increasing speed of deformation shows
an increasing dead zone temperature rise than a more gradual die land temperature rise. It is further seen that extrusion
temperature increase is a function of the container temperature. 相似文献