The multistage drill bit

Provided is a multistage drill bit, including: an outer bit which has a helical outer cut groove on the outer surface of a tip end, and has an insertion hole extended in an inner longitudinal direction at a tip; and an inner bit which is installed so as to be able to move in and out of the insertion...

Ausführliche Beschreibung

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Bibliographische Detailangaben
Hauptverfasser: BAEK, IL CHEON, JOO, DONG WOOK, HUR, CHEOL KI, KWON, JONG JEONG, JUNG, BYEONG GIE, JANG, SE GU, GIL, MIN HYEONG, KIM, KYUNG HEUI, HUR, CHEOL KOO
Format: Patent
Sprache:eng ; kor
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Beschreibung
Zusammenfassung:Provided is a multistage drill bit, including: an outer bit which has a helical outer cut groove on the outer surface of a tip end, and has an insertion hole extended in an inner longitudinal direction at a tip; and an inner bit which is installed so as to be able to move in and out of the insertion hole of the outer bit, has a helical inner cut groove on the outer surface of the tip, and has a connection part at the rear end thereof to allow connection to the outer bit while being inserted into the insertion hole. 본 발명은, 선단 외측면에는 나선형의 외측절삭홈이 형성되고, 선단에는 내측 길이방향으로 연장되도록 삽입구가 마련된 외측비트, 외측비트의 삽입구에 출입 가능하게 설치하며, 선단 외측면에는 나선형의 내측절삭홈이 형성되고, 후단에는 삽입구에 삽입상태로 외측비트와 연결되게 하는 연결부가 마련된 내측비트를 포함하는 다단 드릴비트를 제공한다.