Transmission and Dissipation of Stress Wave at a Sleeve of Percussive Rock Drill.

Rock drills were developed about two hundred years ago, and hydraulic percussion rock drills are about half-century old. Performance and efficiency of rock drills have been increased by a number of researchers and engineers. Percussion energy was dramatically increased with changing the power source from pneumatic to hydraulic pressures; rods and rod joints were improved to endure the high percussion energy; carbide button bits were developed for hard rock drilling. This paper reviewed the previous studies and future issues on the drilling processes with hydraulic percussion rock drills. Studies on the stress wave propagation in rods and rod joints were based on theoretical and graphical methods and recently on numerical simulation. Studies on the interaction between a button bit and rock included crack propagation in rock, force-penetration relationship during drilling, and bit wear. Studies on the factors affecting drilling efficiency and drilling rate made a transition from simple to precise numerical simulations. Finally, important future issues were presented for the further progress of hydraulic percussion rock drills.

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“…Model Reference 1 Lundberg 32) 2 Lundberg 32) 3 Lundberg et al 36) 4 Okubo et al 37) 5 Okubo et al 37) 6 Hashiba et al Vol.133, No.9, 2017 …”

Section: Vol133 No9 2017unclassified

Drilling Processes with Hydraulic Percussion Rock Drills

Hashiba

Fukui

Koizumi

2017

Journal of the Mining and Materials Processing Institute of Jap

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“…この原因を追及する先駆的な研究が 1950 年代に高岡ら 1,9) によってなされた。その結果，ロッドとロッドを接続するスリーブ式ロッド継ぎ手 ( 以下，スリーブと称する ) が弾性波減衰の主因であることが判明した 1) 。引き続き高岡ら 9) は室内実験によりスリーブを通過する弾性波の測定を行い，スリーブの特性を種々検討した。その後も，スリーブに関する多くの実験的研究が行われ [10][11][12][13][14][15][16][17][18] ，スリーブでは①インピーダンスの変化による弾性波の反射や波高の減衰，②弾性波が通過する際のスリーブの揺動，③おねじとめねじ間の相互摩擦によるエネルギーの消費，が生じていることが明らかになった 13) 。①を考慮したモデルの例として CI モデル 14) が挙げられる。②を考慮したモデルとして RM モデル 13) が挙げられる。③に関して三上 11 In this study, a series of percussive long-hole drilling tests using Inada granite was carried out to examine the effect of hole length on drilling performace. Special care was taken to clarify the attenuation of elastic wave at a sleeve coupling which connects the two rods.…”

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