The Development Of Cemented Carbide-polycrystalline Diamond Composite Insert

Down the hole bit drills rocks by the way of impact oriented, impact and rotary, it requests that rock drilling inserts should not only have higher impact resistance but also have extreme wear resistance. Cemented carbide inserts are widely used in down the hole bit due to their higher impact resistance and better hardness, but when down the hole bit drills hard and abrasive rocks, cemented carbide inserts quickly wear due to their inadequate wear resistance, which lead to the failure of the bit. PDC inserts consist of polycrystalline diamond layer and cemented carbide substrate, PDC inserts have extreme abrasiveness, but the impact resistance of PDC inserts are insufficient, so they are hard to satisfy the impact resistance requirement of down the hole bit. Through massive indoor experiments, this task verifies that cemented carbide inserts have higher impact resistance and PDC inserts have extreme abrasiveness.Aiming at the problems of lack of abrasiveness of cemented carbide inserts and insufficient impact resistance of PDC inserts which can not satisfy the operating requirement of down the hole bit, this task also designs a kind of cemented carbide-polycrystalline diamond composite insert with high impact resistance and high abrasiveness which can be used in down the hole bit, it takes the method of drilling hole in cemented carbide insert and welding polycrystalline diamond in the hole, which combines abrasiveness of polycrystalline diamond with impact resistance of cemented carbide. This task tests the impact resistance and abrasiveness of cemented carbide-polycrystalline diamond composite inserts through massive indoor impact resistance experiments and abrasiveness experiments, it proves the performance advantages of cemented carbide-polycrystalline diamond composite inserts.The main conclusions of this task are as below:(1) Through massive indoor impact resistance experiment on cemented carbide inserts, it concludes that the impact resistance of cemented carbide inserts can completely satisfy use requirements of down the hole bit. By the determination of indoor abrasiveness experiments, it verifies that abrasiveness of cemented carbide inserts are lower so that they can not meet requirements of down the hole bit on wear resistance of inserts when it drills extreme hard rocks.(2) Through massive indoor abrasion ratio experiments on PDC inserts, It obtains results that they have extreme abrasiveness so that they can satisfy requirements of down the hole bit on wear resistance of inserts when it drills the extreme hard rocks. Through massive indoor impact resistance experiments, it proves that the impact resistance of PDC inserts are lower so that they can not meet the impact resistance request of high pressure down the hole bit, it also analyzes the reason of inadequate impact resistance of PDC inserts.(3) It designs cemented carbide-polycrystalline diamond composite inserts and analyzes design principles of cemented carbide-polycrystalline diamond composite inserts and it also introduces processing technics of cemented carbide-polycrystalline diamond composite inserts.(4) It proves that impact resistance of cemented carbide-polycrystalline diamond composite inserts are better than PDC inserts and abrasiveness of cemented carbide-polycrystalline diamond composite inserts are better than cemented carbide inserts by massive indoor impact resistance experiments and abrasion ratio experiments.