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Process factors influencing spinning deformation of thin-walled tubular part with longitudinal inner ribs 总被引:3,自引:2,他引:3
As a successively and locally plastic deformation process, ball backward spinning is applied for the purpose of producing thin-walled tubular parts with longitudinal inner ribs. By simplifying ball backward spinning as forward extrusion mechanics model, slab method is used in order to solve spinning force. Based on plastic mechanics, the influence of the process parameters involved on formability of inner ribs as well as the quality defects of spun parts is analyzed so as to present an approach to acquire the desired parts. The quality of inner ribs is one of the critical tasks in obtaining the desired spun workpieces and the height of inner rib depends greatly on spinning material,ball diameter, feed ratio, and wall thickness of tubular blank. The knowledge of the influence of process variables such as ball diameter, feed ratio, and wall thickness of tubular blank on the spinning process is essential to prevent the quality defects of the spun parts and obtain the desired spun parts. 相似文献
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江树勇 《武汉理工大学学报(材料科学英文版)》2012,27(5):811-814
As a successively and locally plastic deformation process, ball spinning is applied to manufacturing thin-walled Nickel-Titanium shape memory alloy (NiTi SMA) tube at high temperature. NiTi SMA tube blank belongs to the as-cast state which consists of a lot of dendritic grains and a few equiaxed grains. The compression tests of NiTi SMA were carried out at various strain rates at high temperature in order to obtain the constitutive model of NiTi SMA. Because NiTi SMA is sensitive to the strain rates at high temperature, rigid-viscoplastic finite element method (FEM) is used to simulate ball spinning of thin-walled NiTi SMA tube in order to analyze the deformation behavior of ball spinning of NiTi SMA tube. Stress fields, strain fields as well as velocity fields is obtained by means of rigid-viscoplastic FEM, which lays the profound foundations for studying the metal flow rule in ball spinning and forming perfect spun NiTi SMA tube. 相似文献
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冷却速度对Ti-50.9%Ni形状记忆合金相变行为和组织的影响(英文) 总被引:1,自引:0,他引:1
为了探索冷却速度对镍钛形状记忆合金相变行为和组织的影响,通过差热扫描、X射线衍射、扫描电镜、X射线荧光分析等方法研究Ti-50.9%Ni(摩尔分数)合金的热处理。结果表明:当冷却速度非常低时(如炉冷)可诱发三级相变的产生;冷却速度对相变温度也有很大的影响,Ms和Mf都随冷却速度的降低而下降,降低冷却速度有利于提高M→A奥氏体相变温度,相变滞后宽度(Af–Mf)随着冷却速度的降低而增大;热处理不能消除镍钛合金热加工时所形成的织构,但能减弱其强度;冷却速度对晶粒大小影响不大。 相似文献
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基于变温度场的镍钛形状记忆合金管滚珠旋压有限元模拟(英文) 总被引:1,自引:0,他引:1
作为一种新的尝试,在高温下应用滚珠旋压制造镍钛形状记忆合金管。将名义成分为Ni50.9Ti49.1(摩尔分数)的镍钛形状记忆合金棒料进行固溶处理,制成用于滚珠旋压的镍钛形状记忆合金管坯。以变温度场和本构方程为基础,用刚粘塑性有限元法来模拟镍钛形状记忆合金管的滚珠旋压,获得了温度场、应力场和应变场,并进行了旋压载荷预测。有限元模拟结果表明,在旋压件的主变形区有大约160℃的温升。从应力场和应变场可以看出,镍钛形状记忆合金管的外壁比内壁更容易满足塑性屈服准则,塑性变形区处于三向压应力状态。径向应变和切向应变为压缩应变,轴向应变为伸长应变。旋压载荷伴随滚珠旋压行程的变化对于预测旋压件的稳定流动具有重要的意义。 相似文献
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基于等通道模具压缩,镍钛铁形状记忆合金经历平面应变压缩变形。通过大塑性变形,可以形成机械诱发马氏体、纳米晶和非晶相。机械诱发马氏体相变明显不同于传统的应力诱发马氏体相变。机械诱发马氏体经常发生在位错滑移之后,而应力诱发马氏体相变发生在位错滑移之前。B19’马氏体的出现有助于镍钛铁形状记忆合金后续塑性变形的协调性。局部高应力场的存在导致部分机械诱发B19’马氏体的稳定,因而在卸载条件下,B19’马氏体无法逆相转变成B2奥氏体。 相似文献
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Based on the process experiments, micrography analysis was dedicated to advancing the understanding of plastic flow of the metal in backward ball spinning of thin-walled tubular part with longitudinal inner ribs. Micrography analysis reveals that severe plastic deformation leads to grain refinement, grain orientation and grain flow line of the spun part. Based on rigid-plastic finite element method, DEFORME3D finite element code was used to simulate and analyze multi-pass backward ball spinning of thin-walled tubular part with longitudinal inner ribs. Finite element simulation results involve the distributions of the strain, the shape variation of the inner ribs as well as the prediction of the spinning loading. 相似文献
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大工程观将科学、技术、非技术要素和工程实践融为一体,形成完整的工程活动系统,注重工程的实践性、系统性、完整性和综合性。《机械制造基础》课程的教学改革与实践,以大工程观教育理念为指导,以工程为主线,在课程的理念、定位与目标上体现了工程内涵;在网络工程图书馆的构建上突出了工程特色;在实践教学改革方面注重了工程实践;在师资队伍建设方面融入了工程特征。 相似文献
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Application of BPANN in spinning deformation ofthin-walled tubular parts with longitudinal inner ribs 总被引:10,自引:0,他引:10
Back-propagation artificial neural network (BPANN) is used in ball backward spinning in order to form thin-walled tubular parts with longitudinal inner ribs. By selecting the process parameters which have a great influence on the height of inner ribs as well as fish scale on the surface of the spun part, a BPANN of 3-8-1 structure is established for predicting the height of inner rib and recognizing the fish scale defect. Experiments data have proved that the average relative error between the measured value and the predicted value of the height of inner rib is not more than 5%. It is evident that BPANN can not only predict the height of inner ribs of the spun part accurately,but recognize and prevent the occurrence of the quality defect of fish scale successfully, and combining BPANN with the ball backward spinning is essential to obtain the desired spun part. 相似文献
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