Mining tricone bit based on roller composite bearing

The invention relates to a mining tricone bit based on a sliding and rolling composite bearing. The mining tricone bit adopts the technical scheme that a roller bearing journal and a boss between the roller bearing journal and a roller bearing journal 5 are both designated cylinders having the diameter of d, i.e. a large journal 4; the specified size of the diameter d of the large journal is the same as the specified size of the diameter D of a large circular hole 9 of a roller cone 2 to form a rolling bearing; 6 to 13 roller slots 8 are uniformly drilled on the inner wall of the large circular hole of the roller cone 2, and each roller slot 8 is internally provided with a roller 3; and the rollers 3, the roller slots 8 and the large journal 4 form the rolling bearing. The roller bearing journal 5 is provided with a ball bearing 6, and a small bearing journal 7 is provided with a sliding bearing or a roller bearing. The invention can greatly reduce the contact stress of the large bearing journal 4, improve th