Volumetric hardening of rock-breaking elements of a ball chisel by cryogenic treatment

Relevance. Roller bits are a rock-breaking tool widely used in geological exploration, in development of mineral deposits using drilling and blasting methods, and in construction of complex engineering structures. In recent decades, work has been underway to improve the design and manufacturing technology of roller chisels to increase their durability. However, the reasons for the failure remain the same. In 80% of the cases the roller bit failure, the cause is the destruction of the bearing supports, due to severe operating conditions and large axial and dynamic loads. Carrying out periodic maintenance and repair of bearing assemblies can reduce the failure rate, but will not solve the problem completely, since other parts of the bit, mainly the cutters may also be in critical condition. It seems reasonable to take an integrated approach to the maintenance of chisels, including, in addition to repairing bearing assemblies, work to restore the strength of rock-breaking elements. One of the most effective and technologically simple methods of volumetric hardening of rock-breaking elements of a chisel that do not require specialized equipment is their cryogenic treatment. Relevance. To determine the positive effect of the use of cryogenic treatment of roller bits on intermediate maintenance or repair of worn-out roller bits. Object. Fatigue destruction of carbide rock-destroying elements of ball bits. Methods. Fatigue failure and methods of volumetric hardening of tungsten carbide rock-breaking elements of roller bits. Results. The proximity of the average values of the penetration of the roller bits before the resource is exhausted due to the failure of the bearing assembly and wear of the rock-breaking elements, which necessitates an integrated approach to the repair of roller bits. The paper describes the effect of cryogenic treatment of hard alloys on the tool life, which consists in the dispersion of stress fields and the creation of a uniform volumetric stress state of compression.