Experimental study on drilling basalt with small diameter drilling tools

摘要

Basalt is one of the potential hard rock targets for drilling sampling in asteroid exploration, and low sampling reaction forces are required in drilling sampling activities of an asteroid. In this paper, the experimental study of drilling basalt with small diameter cemented carbide triangular bit and diamond trepanning drill was carried out, and the drilling thrust force models of basalt drilled by cemented carbide triangular bit and diamond trepanning drill were established, respectively. The ratio of volume removal rate to drilling thrust force was proposed as the evaluation index for the primary selection of drilling tools. The test results showed that the Phi 4 mm cemented carbide triangular bit was the preferred small diameter tool for drilling basalt when the minimum drilling thrust force is 40 N. The Phi 8 mm electroplated diamond trepanning drill was also the preferred small diameter tool for drilling basalt, Its minimum critical drilling thrust is between 100 and 110 N. Further analysis of the drilling thrust model of the two types of drilling tools showed that the drilling thrust force of cemented carbide triangular bit drilling basalt increased with the feed rate, and it increased with the increase of the apex angle of cemented carbide triangular bit. There was minimum and maximum critical drilling thrust force in drilling basalt with diamond trepanning drill. When the drilling thrust force was between the minimum and maximum critical drilling thrust force, the volume removal rate can be improved by increasing the rotating speed of the diamond trepanning drill. This experimental study helps to optimize the drilling tools and set the drilling thrust force and rotating speed when further studying of hard rock sampling for asteroid drilling. (C) 2019 Published by Elsevier Ltd on behalf of COSPAR.