The invention relates to a
coal mine downhole hydraulic jet tree-shaped
drill hole way-type drilling unit. The drilling unit comprises
drill rod, a guider, a
drill bit, a high-pressure hose, a self-propelled
drill bit and a dial. The drill rod is in threaded connection with the front end of the guider. The
drill bit is in threaded connection with the
tail end of the guider. The drill rod, the guider and the
drill bit are used in cooperation, and the two steps of
broaching and guider feeding-in can be finished at the same time. After
broaching is finished, the high-pressure hose and the self-propelled drill bit are used for drilling tree-shaped drill holes in a
coal seam. The
distribution uniformity of the tree-shaped drill holes is controlled by the dial. The
main effect of the drilling unit is to drill main holes of the tree-shaped drill holes of the
coal seam and the tree-shaped drill holes, and uniform permeability increase of the coal seam is achieved. The drilling unit is simple in structure, convenient to operate and suitable for drilling the tree-shaped drill holes in the gas extraction process of the low-air-permeability coal seam.