出口抑制机构对管钻钻削复合材料脱层之影响（英文）

Effects of Exit Suppressed Mechanism on Delamination in Drilling Composite Materials Using Core Drill

复合材料被广泛应用于航天、国防、化工与运输业,但它却是一种让人既爱又恨的构件材料.究其原因,系复合材料既具有优秀的机械特性(高强度-重量比、高破裂韧性与杰出腐蚀抵抗性),又带有一些加工缺陷(脱层、纤维突出、夹层裂缝或热降低).就复合材料的加工而言,钻削是一种重要的制孔方法,并且花费在钻削工具上的成本最多.从成本与生产力的角度看,建立钻削加工的数学模型来获得无脱层的复合材料构件非常重要.由于轴向推力是引起钻削脱层的主要原因,若能降低材料钻削出口的轴向推力,即可避免钻削脱层的发生.文章尝试藉由线弹性破裂力学与能量守恒观念,推导出利用出口抑制机构来管钻复合材料时的轴向推力,并且获得的理论结果与实际的加工经验吻合.这一无脱层复合材料钻孔的研究,未来仍须接受强有力的挑战与考验.

Composite Material is widely used in the aerospace, defense, chemical and transportation industries, but it is both liked and hated because of excellent mechanical characteristics（high strength-to-weight ratio, high fracture toughness and excellent corrosion resistance） and machined defects（delamination, fibre pull-out, interlaminar cracks or thermal degradation）. To the manufacture of composite materials, the drilling is an important process in hole-mak- ing, and the cost of drill bits accounts for the largest amount of money spent in all cutting tools. From the viewpoint of cost and productivity, it is important to set up a mathematical modeling of drilling for delamination-free composite materials. Because the delamination in the drilling is induced mainly by the thrust force, it can be avoided when re- ducing the thrust force at the drill exit of the workpiece. In this paper, according to linear elastic fracture mechanics （LEFM） and energy conservation, an attempt is made to deduce the thrust force in drilling composite materials using core drill with exit suppressed mechanism, and the obtained theoretical results agree well with the practical experi- ence. However, the research of delamination-free hole still needs to accept vigorous challenges and proof in the drilling of composite materials in the future.