Justification of structure and rational design for hammer drills for helical milling

The article presents a method to improve the operation and design of a hammer drill by means of changing the drilling tool trajectory from axial to helical path. The tool penetrates rock mass while rotating toward the plane of a larger chip and induces additional tensile and shearing stresses in rocks, which enables more efficient use of the impact energy in rock fracture. The structure and design layout of a helical milling drill hammer, with additional locking pawl and helical drill shank. From the earlier research and calculations performed for the additional components of the hammer drill, the traveltime attributes and the design values capable to ensure the required factor of safety are determined. The static stress analysis with FEM is undertaken to reveal hazardous cross-sections of parts subjected to the highest loads. The article presents a drilling tool made as a single-flute drill bit with asymmetrical tungsten carbide plate to ensure reduction in energy input of rock fracture by 1.5 times as compared with the bit with the symmetric plate. This modification of the hammer drill involves no essential changes in the main components and parameters of series-production hammer drills.

Sysoev N. I., Grinko A. A., Grinko D. A. Justification of structure and rational design for hammer drills for helical milling. MIAB. Mining Inf. Anal. Bull. 2021;(7):113-124. [In Russ]. DOI: 10.25018/0236_1493_2021_7_0_113.

The study was supported by the Russian Foundation for Basic Research, Project No. 19-35-90079.

N.I. Sysoev¹, Dr. Sci. (Eng.), Professor, e-mail: sysoevngmo@gmail.com,
A.A. Grinko¹, Graduate Student, e-mail: nextdingo@mail.ru,
D.A. Grinko¹, Cand. Sci. (Eng.), Assistant Professor, e-mail: dingo17@mail.ru,
¹ M.I. Platov South-Russian State Polytechnic University (NPI), 346428, Novocherkassk, Russia.

A.A. Grinko, e-mail: nextdingo@mail.ru.

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