Underground polycrystalline diamond compact (PDC) hole-expanding drill bit for coal mines

The utility model relates to an underground polycrystalline diamond compact (PDC) hole-expanding drill bit for coal mines, which comprises a hole-expanding and cave-digging cutter body (2), wherein the hole-expanding and cave-digging cutter body (2) is hinged with a joint (5) in a jet type hole-expanding and cave-digging in the prior art. The underground PDC hole-expanding drill bit is characterized in that the hinging end of the of the joint (5) is fixed with a guide cylinder tube (7) provided with a special-shaped accommodating groove, and the PDC drill bit (8) is fixed on the guide cylinder tube (7). The underground PDC hole-expanding drill bit has the advantages that the structure is simple, the performance is safe and reliable, the use is convenient, and simultaneously, the difficult construction problem of hole expansion in larger hole diameters in each direction in underground coal layers of the coal mines is solved. Compared with the jet type hole-expanding and cave-digging device, the underground PDC