Study of adjustable step-core drill for drilling composite materials

• Main Authors: LI,ZHEN-LIN, 李展霖
• Other Authors: TSAO,CHUNG-CHEN
• Format: Others
• Language: zh-TW
• Published: 2016
• Online Access: http://ndltd.ncl.edu.tw/handle/25542807482344897381

碩士 === 大華科技大學 === 機電研究所 === 104 === Drilling is extremely important processing for carbon fiber-reinforced composite materials. Carbon fiber-reinforced composite material have high hardness, high strength, thermal conductivity of poor and low interlaminar strength characteristics of difficult machining materials. General drilling carbon fiber-reinforced composite materials in industrial applications experience prone to layered, torn, delamination defects, and most occurred in the exit hole, tearing and produced by drilling of burr edge sharp enough, resulting in carbon fiber-reinforced composite materials not completely cut off. The object of this study is to develop an adjustable step-core drill for drilling carbon fiber-reinforced composite materials, which is to verify the feasibility of this new tool design. This new drill apart from adjusting the elongation can also make worn tool replacement as well as two various drilling can be carried out in single trip. In this study, the twist drill, inner-outer drill (3) and inner-outer drill (4) were selected for the drilling research. From the experimental results showed that the thrust of twist drill is larger than the inner-outer drill (3) and inner-outer drill (4) because this design tool was longer. It is more suitable for low-CNC spindle speed (1000 rpm) and low feed rate (30 mm/min) in drilling composites. As to the inner drill elongation of the amount, it will affect the thrust force of the size of its drilling. Within or close to the drill thickness of composite materials as a priority consideration, which can reduce thrust when tungsten twist drill within the composite, followed by the outer drill drilling composites induced thrust force generated. This study was designed by an adjustable drilling tool in drilling different experiments. Verifiable adjustable step drill for drilling carbon fiber-reinforced composite materials is feasible.