共查询到19条相似文献,搜索用时 671 毫秒
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工艺参数对金属粉末共注射成形芯层熔体形貌的影响 总被引:1,自引:0,他引:1
分别以316L(40%,体积分数)、316L(60%)为芯、壳层喂料,研究工艺参数如壳层熔体温度、壳层注射速度和延迟时间对粉末共注射芯层熔体形貌的影响;分析工艺参数对金属共注射芯层形貌影响的流变学机理。结果表明:芯层熔体前沿呈蘑菇状;固定芯层熔体温度,随着壳层熔体温度的升高,芯层穿透深度从148 mm减小到136 mm,最大穿透宽度从133 mm增加到139 mm;随壳层注射速度的增加,芯层穿透深度从148 mm减小到143 mm,而芯层穿透宽度的变化规律不明显;随着芯层熔体延迟时间的增大,芯层穿透深度从146 mm增加到154 mm,穿透宽度从118 mm增加到136 mm。 相似文献
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为了控制梯度复合铸锭横截面上的内层组织分布,通过改变内熔体浇口在结晶器中心线上的不同位置,采用双流浇注半连续铸造技术制备内层合金宽度不同的7075/6009梯度复合铸锭,分析不同内层合金宽度的铸锭横截面上的宏观组织、硬度分布及其微观组织的二次枝晶间距,探讨内熔体浇口位置对双流浇注半连续铸造技术的内熔体形成液穴的影响.结果表明:随着内熔体浇口探入结晶器深度的加大,铸锭横截面的内层合金组织的宽度逐渐加大,洛氏硬度始降点逐渐外移,铸锭横截面的Zn含量始降点也逐渐外移,半径为10 mm处的二次枝晶间距逐渐缩小. 相似文献
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立式离心场下钛合金熔体充填及凝固过程研究 总被引:2,自引:0,他引:2
研究立式离心场下不同铸造工艺参数对钛合金熔体的充填及凝固缺陷形成的影响。结果显示,立式离心场下得到的钛合金铸件质量优于重力场下的铸件。立式离心场下,合金熔体由于受离心力和科氏力的作用,沿着与旋转方向相对的型壁进行充填,且熔体的截面面积随充填长度的增加而逐渐减小,但是在内浇口处由于速度降低导致截面面积有所回升。此外,铸型的旋转方向,旋转半径及旋转速度直接影响铸件缺陷的形成。旋转方向直接影响合金熔体的充填顺序,进而影响合金熔体的凝固顺序及缺陷位置。实验结果显示,旋转半径及旋转速度的增加有利于减少铸件的缺陷体积。 相似文献
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通过对于多型腔腰柱形滑块形体要素和缺陷预期及浇口平衡值的分析,得出了塑件具有垂直开闭模方向的型孔要素,采用了斜导柱滑块抽芯机构。由于腰柱形滑块存在着弓形高“障碍体”要素,采用了在弧线的象限点处设置分型面以避让弓形高“障碍体”。但导致了封闭定模型腔的塑料熔体填充是自下而上进行,气体难以排出造成腰柱形滑块出现气泡、填充不足、过热痕、流痕和银纹等缺陷,经分析可在动模型芯分型面浇口对面处设置冷料穴。该模具虽有8个型腔,但由于型腔相同,各个型腔分流道长度相同,侧向浇口长度相等,符合浇口平衡条件。因此,注射模结构设计合理,多型腔腰柱可实现高效高质量加工。 相似文献
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基于Moldflow的基座注射成型工艺与注射模设计 总被引:1,自引:1,他引:0
采用Moldflow软件对精密微型电连接器件中的基座进行了浇口位置和注射成型工艺优化。通过对熔体充填型腔的过程分析,确定了塑件成型的最佳浇口位置和熔体充填时间,针对塑件成型后的体积收缩率分析得出了注射成型的最佳熔体温度,分析了模具温度对制件收缩率和最大注射压力的影响。结合模拟分析的结果进行了模具与注射工艺参数优化设计,从而获得了高质量的塑件,降低了生产成本,缩短了产品开发周期。 相似文献
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In this work,the shear model of metal melt flowing on vibration surface is established,and coupling effects of vibration and shear on the distribution of shear stress in melt and melt solidification microstructure are analyzed.Calculation results show that the transition of melt from laminar flow to turbulent flow occurs earlier with increasing vibration frequency and vibration amplitude.In the laminar flow melt,shear stress in melt decreases with increasing vertical length,but it decreases firstly and then stabilizes with increasing flow length.In the turbulent flow melt,shear stress decreases firstly and then stabilizes with increasing vertical length,but it increases with increasing flow length.With the increase in vibration frequency and amplitude,shear stress along flow direction in laminar flow melt increases,while shear stresses along both flow direction and vertical direction in turbulent flow melt increase.Shear stress in melt decreases with increasing length along vertical direction.With the increase in flow length,shear stress decreases firstly and then stabilizes in laminar flow melt,while it increases in turbulent flow melt.With the increase in vibration frequency and amplitude,shear stress increases in laminar flow melt,while it stabilizes in turbulent flow melt.Based on theoretical calculation,the maximum shear stress in melt during vibration shear flow is always much lower than the yield strength of a-Al grain,so the shear stress induced by vibration shear flow cannot break columnar crystal,which agrees with the experiment result.So,the model can explain the shear constitutive relation of melt flow on vibration surface relatively well. 相似文献
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目的 研究有限尺寸矩形正交各向异性薄膜/基底系统在单向压缩下的表面屈曲。方法 采用Kirchhoff-Love薄板理论和von Kármán板理论分析了临界应变和后屈曲形貌演化,考察了材料的各向异性性质及薄膜的几何参数对表面屈曲行为的影响。结果 一般来说,薄膜/基底系统的初始屈曲总是对应于多个波峰,在薄膜长度相同的条件下,薄膜宽度的改变可以影响波峰的数目。在薄膜的各向异性性质特别强烈的时候,薄膜/基底结构表现出一些显著的特点。其中之一是在外加应变超过临界应变之后,边缘幅值随着薄膜宽度的增大而增大,而中心幅值则急剧减小。结论 中心和边缘幅值的差距越来越大,最终导致薄膜后屈曲形貌幅值在宽度方向上的巨大差异,并预示随着外加应变的逐渐增大,宽度方向可能演变出其他的屈曲模式。 相似文献
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A plastic plate with surface micro features was injection molded to investigate the effect of pressure rise of melt on the replication of the micro structures. Prism pattern, which is used in many optical applications, was selected as a model pattern. The prism pattern is 50 μm in pitch and 108° in the vertical angle. The overall size of the plate was 335 mm×213 mm and the thickness of the plate varied linearly from 2.6 mm to 0.7 mm. The prism pattern was firstly machined on the nickel plated core block using micro diamond tool and this machined pattern core was installed in a mold for injection molding of prism patterned plate. Polymethyl methacrylate (PMMA) was used as a molding material. The pressure and temperature of the melt in the cavity were measured at different positions in the cavity and the replication of the pattern was also measured at the same positions. The results show that the pressure or temperature profile through the process depends on the shape and the size of the plate. The replication is affected by the temperature and pressure profiles at the early stage of filling, which is right after the melt reaches the position to be measured. 相似文献