钻头芯管（反循环排碴管）的下端留有吸水排碴口并焊有中心切削刃，其外周放射状固定三枚钻头主翼。钻头主翼上设有圆弧形导向槽和导向销，下端焊有切削刃。另有三枚扩大翼与钻头主翼重合，扩大翼 The lower end of the drill core pipe (reverse circulation ballast pipe) is provided with a water suction and drainage port and a central cutting edge is welded, and the outer periphery of the drill core is fixed with three main bits of the drill bit radially. The main wing of the drill bit is provided with an arc-shaped guide groove and a guide pin, and the lower end is welded with a cutting edge. Another three expansion wings coincide with the main wing of the drill bit to expand the wings