Contact pressure evolution and its relation to wear in sheet metal forming
Contact pressure evolution and its relation to wear in sheet metal forming
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DOI：
10.1016/j.wear.2008.04.042
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发表时间：
2008-11
期刊：
影响因子：
5
通讯作者：
M. Pereira;Wenyi Yan;B. Rolfe
中科院分区：
文献类型：
--
作者：
M. Pereira;Wenyi Yan;B. Rolfe
对于一个给定的金属板成形过程，接触压力分布的准确测定是朝着估计刀具寿命的一个重要步骤。这项调查利用有限元（FE）分析模型和解释的演变和分布的模具半径上的接触压力，在整个持续时间的通道形成过程。结果发现，一个典型的双峰稳态接触压力响应存在的大部分的过程。然而，这之前是一个初始的瞬态响应，其特征是极大的局部接触压力，这是稳态峰值压力的两倍以上。预测的接触压力行为的有效性进行了评估，通过详细的数值分析，并通过检查实验冲压操作的磨损响应。实验结果表明，瞬态响应的高接触压力区对应于严重的粘滞磨损机制。因此，瞬态响应可能是主要意义的工具磨损响应，从而质疑传统的弯曲拉伸下的金属板冲压工艺的磨损试验的适用性。最后，进行了参数研究，检查的稳态和峰值瞬态接触压力的主要工艺参数的影响，使用开发的有限元模型。结果表明，弯曲比和坯料的极限抗拉强度对接触压力峰值的影响最大。与工艺相关的主要参数，摩擦系数和压边保持器力，被发现只有很小的影响。
For a given sheet metal forming process, an accurate determination of the contact pressure distribution is an essential step towards the estimation of tool life. This investigation utilizes finite element (FE) analysis to model and explain the evolution and distribution of contact pressure over the die radius, throughout the duration of a channel forming process. It was found that a typical two-peak steady-state contact pressure response exists for the majority of the process. However, this was preceded by an initial transient response, characterized by extremely large and localized contact pressures, which were more than double the magnitude of the steady-state peak pressure. The validity of the predicted contact pressure behavior was assessed via detailed numerical analysis and by examining the wear response of an experimental stamping operation. The experimental results revealed that the high contact pressure zones of the transient response corresponded to a severe galling wear mechanism. Therefore, the transient response may be of primary significance to the tool wear response; thus questioning the applicability of traditional bending-under-tension wear tests for sheet metal stamping processes. Finally, a parametric study was conducted, examining the influence of the major process parameters on the steady-state and peak transient contact pressures, using the developed FE model. It was found that the bend ratio and the blank material ultimate tensile strength had the most influence on the peak contact pressures. The main process-related parameters, friction coefficient and blank holder force, were found to have only a minor influence.