Loading tests of retaining tricone bit bearing using physical model

Abstract

Tricone bits are currently less commonly used as compared with PDC bits. Tricone bits are mainly used in drilling in difficult geotechnical conditions and in blasthole drilling in open pit mines. The main disadvantage of tricone bits is the relatively short life. The main cause of the age limit is failure of the retaining ball bearing due to destruction of raceway and journal shoulder under high contact and bending stresses. Based on the provisions of the similarity theory, the physical model of the retaining drill bit bearing has been manufactured. The paper presents the data of the retaining bearing testing using a friction and wear testing machine, namely, the temporal variations in temperature, frictional torque and clearances of bearings. The temperature and the heat rating of the bearing are related. In the extreme conditions of operation at deficiency of lubrications, the contact stresses in the rings and balls of bearing, as well as their temperatures exceed greatly the allowable values. The authors propose using the procedure in engineering of a roller drill bit.