Assessment of hand-type hammer drill bits under percussive loading

Download

index.pdf

Date

2007

Author

Demir, Osman Koray

Metadata

Show full item record

Item Usage Stats

221
views

80
downloads

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.

Subject Keywords

Mechanical Engineering.

URI

http://etd.lib.metu.edu.tr/upload/12608282/index.pdf
https://hdl.handle.net/11511/16727

Collections

Graduate School of Natural and Applied Sciences, Thesis

Suggestions

OpenMETU
Core

Analysis of welding parameters in gas metal arc welding by a welding robot Erener, Yavuz; Arıkan, Mehmet Ali Sahir; Department of Mechanical Engineering (2006) In Robotic Gas Metal Arc Welding process, the welding parameters controlled by the welder (travel speed of the welding torch, wire feed speed, current, voltage, wire diameter, etc.) should be considered to obtain a desired welding quality. To design an appropriate welding model for the used equipment, the effects of each parameter should be studied by carrying out an adequate number of experiments. The welding process is described by analyzing the experimental data to define the relationships between the we...
Experimental and numerical analysis of compression on a forging press Biçer, Gökhan; Gökler, Mustafa İlhan; Department of Mechanical Engineering (2010) Forging is a metal forming process which involves non-linear deformations. Finite element and finite volume software programs are commonly used to simulate the process. In these simulations, material properties are required. However, stress-strain relations of the materials at some elevated temperatures are not available in the material libraries of the related software programs. In this study, the stress-strain curves have been obtained by applying the Cook and Larke Simple Compression Test to AISI 1045 st...
Analysis of roll-forging process Karacaovalı, Hakan; Gökler, Mustafa İlhan; Department of Mechanical Engineering (2005) Roll-forging is a metal forming process and mainly used for preform forging of long parts prior to press or hammer forging in the industry. Variable cross sections through the length of billet can be obtained by roll-forging to acquire an adequate distribution of material to the next forging stages. In the design of process and dies used in roll-forging, there are some empirical techniques in literature. However these techniques only provide approximate reduction ratio and elongation during the process and ...
Numerical analysis of ablation process on a two dimensional external surface Aykan, Fatma Serap; Dursunkaya, Zafer; Department of Mechanical Engineering (2005) The thermal response analysis of an ablative material on a two dimensional external surface is performed. The method is applied to both rectangular and cylindrical coordinate systems, where rectangular coordinate system is used for comparison with results available in literature. The current study solves the decomposition of the material at high temperatures by using the nth order Arrhenius equation but excludes the removal of char from the surface due to mechanical erosion or phase change and considers tha...
Analysis of warm forging process Aktakka, Gülgün; Darendeliler, Haluk; Department of Mechanical Engineering (2006) Forging is a metal forming process commonly used in industry. Forging process is strongly affected by the process temperature. In hot forging process, a wide range of materials can be used and even complex geometries can be formed. However in cold forging, only low carbon steels as ferrous material with simple geometries can be forged and high capacity forging machinery is required. Warm forging compromise the advantages and disadvantages of hot and cold forging processes. In warm forging process, a product...

Citation Formats

O. K. Demir, “Assessment of hand-type hammer drill bits under percussive loading,” M.S. - Master of Science, Middle East Technical University, 2007.