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Effects of die land length and geometry on curvature and effective strain of profiles produced by a novel sideways extrusion process
Journal of Materials Processing Technology ( IF 6.7 ) Pub Date : 2020-08-01 , DOI: 10.1016/j.jmatprotec.2020.116682
Wenbin Zhou , Junquan Yu , Jianguo Lin , Trevor A. Dean

Abstract In the present investigation, effects of length and geometry of die land/bearing on curved profiles/sections produced by a novel process, differential velocity sideways extrusion (DVSE), were studied through physical experiments using plasticine as a model material and finite element modelling. Profile curvature decreases as die land length increases due to its negative influence on exit velocity gradient, and a straight profile is extruded when the ratio of die land length to die orifice diameter exceeds a critical value l 0 which increases as extrusion ratio λ increases and extrusion velocity ratio v 2 / v 1 decreases. Generally, effective strain level of the extrudate slightly increases as the die land length increases. Larger die land length increases the frictional areas between extrudate surface layers and die land (and mandrel for tube extrusion), generating zone of shear along the profile edge and thus increases surface layer effective strain. As a result, the strain homogeneity over the cross-section or wall thickness (for tube extrusion) is decreased. Compared with a sharp die land/container transition corner, a chamfered or radiused die land transition corner leads to an increased curvature due to the decreased effective land length, while it decreases overall effective strain level in the cross-section and strain homogeneity as a result of lower effective strain rate across the deforming region. A sharp die land transition corner is recommended for achieving a relatively large and homogenous effective strain in the cross-section.

中文翻译:

模具刃带长度和几何形状对新型横向挤压工艺生产的型材曲率和有效应变的影响

摘要 在目前的调查中,通过使用橡皮泥作为模型材料和有限元建模的物理实验,研究了模具边缘/轴承的长度和几何形状对由一种新工艺,差速横向挤压 (DVSE) 产生的弯曲轮廓/截面的影响。 . 由于其对出口速度梯度的负面影响,轮廓曲率随着模棱边长度的增加而减小,并且当模棱棱边长度与模孔直径之比超过临界值 l 0 时挤出直线轮廓,该临界值随着挤压比 λ 的增加和挤压而增加速度比 v 2 / v 1 减小。通常,挤出物的有效应变水平随着模具刃带长度的增加而略微增加。较大的模具刃带长度增加了挤出物表面层和模具刃带(以及用于管材挤出的心轴)之间的摩擦面积,沿型材边缘产生剪切区,从而增加了表面层有效应变。结果,横截面或壁厚(对于管挤出)的应变均匀性降低。与尖锐的模具刃带/容器过渡角相比,倒角或圆角刃型刃带过渡角会由于有效刃带长度减少而导致曲率增加,同时降低横截面中的整体有效应变水平和应变均匀性整个变形区域的有效应变率较低。建议使用尖锐的模具边缘过渡角,以在横截面中获得相对较大且均匀的有效应变。沿轮廓边缘产生剪切带,从而增加表面层有效应变。结果,横截面或壁厚(对于管挤出)的应变均匀性降低。与尖锐的模具刃带/容器过渡角相比,倒角或圆角刃型刃带过渡角会由于有效刃带长度减少而导致曲率增加,同时降低横截面中的整体有效应变水平和应变均匀性整个变形区域的有效应变率较低。建议使用尖锐的模具边缘过渡角,以在横截面中获得相对较大且均匀的有效应变。沿轮廓边缘产生剪切带,从而增加表面层有效应变。结果,横截面或壁厚(对于管挤出)的应变均匀性降低。与尖锐的模具刃带/容器过渡角相比,倒角或圆角刃型刃带过渡角会由于有效刃带长度减少而导致曲率增加,同时它会降低横截面中的整体有效应变水平和应变均匀性整个变形区域的有效应变率较低。建议使用尖锐的模具边缘过渡角,以在横截面中获得相对较大且均匀的有效应变。横截面或壁厚(对于管材挤出)的应变均匀性降低。与尖锐的模具刃带/容器过渡角相比,倒角或圆角刃型刃带过渡角会由于有效刃带长度减少而导致曲率增加,同时降低横截面中的整体有效应变水平和应变均匀性整个变形区域的有效应变率较低。建议使用尖锐的模具边缘过渡角,以在横截面中获得相对较大且均匀的有效应变。横截面或壁厚(对于管材挤出)的应变均匀性降低。与尖锐的模具刃带/容器过渡角相比,倒角或圆角刃型刃带过渡角会由于有效刃带长度减少而导致曲率增加,同时降低横截面中的整体有效应变水平和应变均匀性整个变形区域的有效应变率较低。建议使用尖锐的模具边缘过渡角,以在横截面中获得相对较大且均匀的有效应变。而由于整个变形区域的有效应变率较低,它会降低横截面中的整体有效应变水平和应变均匀性。建议使用尖锐的模具边缘过渡角,以在横截面中获得相对较大且均匀的有效应变。而由于整个变形区域的有效应变率较低,它会降低横截面中的整体有效应变水平和应变均匀性。建议使用尖锐的模具边缘过渡角,以在横截面中获得相对较大且均匀的有效应变。
更新日期:2020-08-01
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