0
TECHNICAL PAPERS

Analytical and Experimental Study of Determining the Optimal Number of Wedge Shape Cutting Teeth in Coring Bits Used in Percussive Drilling

[+] Author and Article Information
Yinghui Liu

Department of Mechanical & Industrial Engineering, Northeastern University, 360 Huntington Avenue, Boston, MA 02115

Constantinos Mavroidis1

Department of Mechanical & Industrial Engineering, Northeastern University, 360 Huntington Avenue, Boston, MA 02115mavro@coe.neu.edu

Yoseph Bar-Cohen

Jet Propulsion Laboratory (JPL), California Institute of Technology, M.S. 125-224, 4800 Oak Grove Drive, Pasadena, CA 91109yosi@jpl.nasa.gov

Zensheu Chang

Jet Propulsion Laboratory (JPL), California Institute of Technology, M.S. 125-224, 4800 Oak Grove Drive, Pasadena, CA 91109

1

Corresponding author.

J. Manuf. Sci. Eng 129(4), 760-769 (Sep 21, 2006) (10 pages) doi:10.1115/1.2515345 History: Received November 01, 2005; Revised September 21, 2006

In this paper we study the design of the coring bits with wedge-shape cutting teeth of vibratory drills that percussively penetrate into brittle material. The overall coring bit specific energy is analytically derived as a function of the cutting teeth spacing and teeth number. It is found that given the coring bit dimensions and rock material properties, there exist an optimal spacing/depth ratio and an optimal tooth number that minimize the coring bit specific energy and hence maximize the coring bit’s drilling rate. Experimental drilling tests were performed to corroborate the analytical results. It was shown that the laboratory drilling tests follow the trend predicted by the theoretical analysis.

Copyright © 2007 by American Society of Mechanical Engineers
Your Session has timed out. Please sign back in to continue.

References

Figures

Grahic Jump Location
Figure 1

Shape of experimental force-penetration curve

Grahic Jump Location
Figure 2

Force diagram according to Ref. 8

Grahic Jump Location
Figure 3

USDC schematic (left); USDC coring Bit schematic (right)

Grahic Jump Location
Figure 4

Single wedge tooth penetration model

Grahic Jump Location
Figure 5

Mechanical analysis of the i+1 chip

Grahic Jump Location
Figure 6

Mechanical analysis considering the friction

Grahic Jump Location
Figure 7

Theoretical force–penetration curve for brittle crater model

Grahic Jump Location
Figure 8

Physical model of penetration considering the interaction between adjacent teeth: Coulomb–Mohr failure theory

Grahic Jump Location
Figure 11

Coulomb–Mohr failure theory: (a) variation of the overall specific energy as a function of the spacing/depth ratio; and (b) variation of the overall specific energy as a function of the teeth number for constant rate assumption

Grahic Jump Location
Figure 12

Half wedge angle 30deg: (a) comparison of the variation of the overall specific energy as a function of the spacing/depth ratio in the cases of cutting teeth edge/rock with friction and without friction; (b) comparison of the variation of the overall specific energy as a function of the teeth number in the cases of cutting teeth edge/rock with friction and without friction

Grahic Jump Location
Figure 13

Half wedge angle 60deg: (a) comparison of the variation of the overall specific energy as a function of the spacing/depth ratio in the cases of cutting teeth edge/rock with friction and without friction; (b) comparison of the variation of the overall specific energy as a function of the teeth number in the cases of cutting teeth edge/rock with friction and without friction

Grahic Jump Location
Figure 14

Experimental apparatus

Grahic Jump Location
Figure 15

A 12-teeth coring bit on drilling

Grahic Jump Location
Figure 16

Experimental load–penetration curves for 6-teeth sharp bit (red, dashed line) and dull bit (green, solid line) into limestone

Grahic Jump Location
Figure 17

Experimental load–penetration curves for two 12-teeth coring bits into limestone

Grahic Jump Location
Figure 18

Experimental load–penetration curves for 6-teeth bit (red, dashed line) and 12-teeth bit (blue, solid line) into limestone

Grahic Jump Location
Figure 10

Coulomb–Mohr failure theory: (a) variation of the overall specific energy as a function of the spacing/depth ratio; and (b) variation of the overall specific energy with teeth number for constant load assumption

Grahic Jump Location
Figure 9

Variation of the specific energy as a function of the half wedge angle and the rock properties: (a) prediction for three values of the angle of internal friction ϕ for the case of cutting with frictionless wedge; and (b)–(d) comparisons of two cases of cutting edge with friction and without friction for three values of the angle of internal friction ϕ.

Tables

Errata

Discussions

Some tools below are only available to our subscribers or users with an online account.

Related Content

Customize your page view by dragging and repositioning the boxes below.

Related Journal Articles
Related eBook Content
Topic Collections

Sorry! You do not have access to this content. For assistance or to subscribe, please contact us:

  • TELEPHONE: 1-800-843-2763 (Toll-free in the USA)
  • EMAIL: asmedigitalcollection@asme.org
Sign In