摘要
Bulge is a defect that causes geometrical inaccuracy and premature failure in the innovative incremental sheet forming (ISF) process. This study has two-fold objectives:(1) knowing the bulging behavior of a Cu clad tri-layered steel sheet as a function of forming conditions, and (2) analyzing the bending effect on bulging in an attempt to identify the associated mechanism. A series of ISF tests and bending analysis are performed to realize these objectives. From the cause-effect analysis, it is found that bulge formation in the layered sheet is sensitive to forming conditions in a way that bulging can be minimized utilizing annealed material and performing ISF with larger tool diameter and step size. The bending under tension analysis reveals that the formation of bulge is an outgrowth of bending moment that the forming tool applies on the sheet during ISF. Furthermore, the magnitude of bending moment depending upon the forming conditions varies from 0.046 to 10.24 N·m/m and causes a corresponding change in the mean bulge height from 0.07 to 0.91 mm. The bending moment governs bulging in layered sheet through a linear law. These findings lead to a conclusion that the bulge defect can be overcome by controlling the bending moment and the formula proposed can be helpful in this regards.
鼓包是渐进成形工艺(ISF)中引起几何误差和过早失效的一种缺陷。本研究的目的是:(1)了解覆铜三层钢板的鼓包行为与成形条件之间的关系;(2)分析弯曲对鼓包的影响,并试图得出相关机理。为此,进行一系列的渐进成形和弯曲实验。结果表明:层状板材的鼓包形成对成形条件较敏感,可以通过采用退火材料,更大的刀具直径和步长进行ISF加工,使鼓包减到最小,弯曲分析表明,鼓包是成形工具在ISF过程中施加在板材上的弯曲力矩作用的结果;当力矩从0.046增加到10.24 N·m/m时,鼓包的平均高度从0.07增加到0.91 mm;层状板材中的鼓包与弯曲力矩呈线性关系。综上,通过控制弯曲力矩可以克服鼓包缺陷,本研究提出的公式对相关研究有一定的帮助。
基金
the financial help and technical support that King Abdulaziz University provided for this research work
