FRP製薄板パネル用穴あけドリルの開発
■機械金属部 廣崎憲一 山下順広
■東興産業（株） 辻谷正彦 間戸朋之
炭素繊維強化プラスチック(CFRP)やガラス繊維強化プラスチック(GFRP)等のFRP材料を切削する場合には，FRP材料自身が強化繊維シートの積層材であるため，繊維の毛羽立ちや表層剥離が問題となる。特に，板厚の薄いパネル部品にドリルで穴あけをする場合，材料がたわみ易いことから，反動による跳ね返りが生じ，これらの問題が一層生じ易くなる。本研究では，たわみの要因となる切削抵抗を低減化し，かつ，毛羽立ちや表層剥離を防ぐことを目的に，先端部に突き出した小さなドリルを備え，後段には鋭角の切れ刃を持つ「段付き複合アングルドリル」を考案した。その結果，GFRP薄板材料の片持ち固定条件下のドリル加工試験において，考案ドリルは送り量を標準条件の2倍とする高送り条件にも拘わらず，最大切削抵抗の低減化によりパネルの跳ね返りを抑制でき，従来のドリルに比べて加工穴の品質改善が図られた。
キーワード: 繊維強化プラスチック，穴あけ，ドリル，切削抵抗，デラミネーション
Development of Drilling Tools for Thin Panels Made of Fiber-reinforced Plastics
Kenichi HIROSAKI, Yorihiro YAMASHITA, Masahiko TSUJITANI and Tomoyuki MATO
When materials made of carbon fiber reinforced plastics (CFRP) or glass fiber reinforced plastics (GFRP) are cut, problems such as uncut fibers remaining and delamination of layers can occur. This is due to the composition of FRP materials, which are made by laminating several sheets of strong fiber. These problems are particularly frequent in the case of drilling a thin FRP panel, due to the rebound motion that occurs after it bends. In this study, we proposed a new drilling tool, a “step multi-angle drill“, which consists of a small drill at the front tip and a double-angle cutting blade at the back, for the purpose of reducing cutting force that causes work bending, and preventing uncut fibers and delamination. In a drilling test conducted on thin GFRP panels in an overhung condition, the proposed drilling tool prevented bending of the works by reducing the maximum cutting force, and improved the quality of cut holes compared with a conventional tool, even though the test was conducted at a feeding speed twice as high as the normal operation speed.
Keywords: FRP, drilling, drill, cutting force, delamination
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