Water flushing of rock chips from horizontal holes drilled by rotary percussion.

[摘要] The flushing flow rate required to maximise penetrationrate of holes drilled by rotary percussion is dependanton drilling parameters and chip size. Experimental workto determine the optimal flushing water flow rate for twocommon drilling situations was undertaken. It consistedof drilling, analysis of chip samples and flowvisualization. A computer modal to predict flow rate wasdeveloped. Its output and the experimental results Werecombined to explain the relationship between penetrationrate and flow rate.All chips should be fiushed from the gap between the bitand the end of the hole in the time between hammer blows(ie. - within the duration of a percussion cycle). Asflow rate increases, flushing improves and thereforepenetration rate increases. Once flushing is adequatethere is no mechanism for further increases inpenetration rate, thus it remains constant andindependent of further increases in flow.

[发布机构] University of the Witwatersrand