Structure Features and Working Principle of Big Through-hole On-off Drill

Nowadays, Drilling for gas pre-drainage is an important regional outburst prevention measure for outburst coal seam. Compared with gas extraction method of withdrawing and uncorrected borehole, for drilling in the low permeability soft and outburst seam, there are some advantages using the process of screen pipe in gas extraction. However, due to the soft and broken coal seam, it easily causes drills collapse and leads screen pipe can't reach to the bottom of hole, and then reduces the practical gas extraction section and influences gas extraction effect, which brings out hidden trouble for safety production of coal mine. To solve these problems, the article designed the big through-hole on-off drill, and its working principle and structure characteristics were analyzed, and validate its use effect through field test.