Machinability of wood fiber/polyethylene composite during orthogonal cutting
Machinability of wood fiber/polyethylene composite during orthogonal cutting
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DOI：
10.1007/s00226-020-01256-4
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发表时间：
2021-01-04
影响因子：
3.4
通讯作者：
Guo, Yong
中科院分区：
文献类型：
--
作者：
Guo, Xiaolei;Wang, Jinxin;Guo, Yong
木纤维/聚乙烯复合材料（WFPEC）是由天然木纤维和可回收的聚乙烯塑料复合而成的一种环保型复合材料。然而，更好地了解切屑的形成和表面损伤机制的WFPEC是必不可少的，以改善其可加工性，扩大外部和内部的应用。通过改变切削深度的正交切削试验，分析了切削效率和表面质量之间的差异，研究了WFPEC的可加工性。切屑形成过程由每秒5000帧的高速摄像系统记录。通过扫描电子显微镜观察表面形貌。结果表明，切屑形态由浅切削深度下的连续剪切过程转变为深切削深度下的不连续塑性断裂。切削深度较浅时，表面形貌主要表现为基体扁平化，而切削深度较大时，表面形貌主要表现为基体纤维撕裂。纤维的拔出/断裂和脱粘与纤维取向角和纤维束直径有关，而与切割深度无关。综合来看，随着切削深度的增加，工件材料在切削区域的韧性降低。为了避免基体纤维撕裂，在精加工过程中应使用较浅的切割深度，以保持表面质量。相比之下，预切割可以以深切割深度执行，以便提高切割效率。
Wood fiber/polyethylene composite (WFPEC) is composed of a natural wood fiber and a recyclable polyethylene plastic, which is normally used as an environmental protection composite material. However, better knowledge of chip formation and surface damage mechanism of WFPEC is essential to improve its machinability for extending exterior and interior applications. In this article, machinability of WFPEC was investigated by analyzing the disparity between cutting efficiency and surface quality through a group of orthogonal cutting experiments with change of cutting depth. The chip formation process was recorded by a high-speed camera system with 5000 frames per second. Surface topography was observed by a scanning electron microscope. The results showed that the chip morphology changed from continuous cutting governed by a continuous shearing process under the shallow cutting depth, to a discontinuous cutting governed by plastic fracture under the deep cutting depth ahead of the tool tip. Flattened matrix was the main form of surface topography caused by shallow cutting depth, while matrix-fiber tearing was caused by deep cutting depth. Pullout/fracture and debonding of fibers were related to the fiber orientation angle and the diameter of fiber bundles, but not to the cutting depth. Taken together, the toughness of the workpiece material in the cutting region decreased with the increase in cutting depth. To avoid matrix-fiber tearing, shallow cutting depth should be used during finishing to maintain surface quality. In contrast, pre-cutting can be performed with a deep cutting depth in order to improve the cutting efficiency.