The task of a drill bit in percussive drilling is to transport the initial kinetic energy
of the hammer to the workpiece in terms of stress waves. The efficiency of this
transportation and the stresses that the drill bit is exposed to during the process is
dependent on the nature of the stress waves. In hand-type hammer drilling,
changing dimensions of the bit means changing conditions for the propagation and
interaction of the stress waves.
In this study, using finite element method, wave propagation and interaction in
hand-type hammer drill bits is investigated with respect to drill bit dimensions. The
main aim is to assess the effect of length and thickness on the efficiency and stress
history of a hand-type drill bit. The results are evaluated in regard to workpiece
hardness, which is a factor changing the effect of dimensions. In addition, chiseling
test, which is used to prove bits under percussive loading, is carried out to detect
differences between thin and thick drill bits, and the results are explained with the
help of finite element simulations.
Conclusions are drawn revealing the efficiency and stress history of drill bits under
percussive loading with respect to thickness, length and workpiece hardness.
Finally, it is seen that the real-life results of chiseling test are in agreement with the
simulation results.
| Identifer | oai:union.ndltd.org:METU/oai:etd.lib.metu.edu.tr:http://etd.lib.metu.edu.tr/upload/12608282/index.pdf |
| Date | 01 April 2007 |
| Creators | Demir, Osman Koray |
| Contributors | Caliskan, Mehmet |
| Publisher | METU |
| Source Sets | Middle East Technical Univ. |
| Language | English |
| Detected Language | English |
| Type | M.S. Thesis |
| Format | text/pdf |
| Rights | To liberate the content for public access |
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