Application of intermediate elements made of alloys with thermoelastic phase transformations for fixing teeth in drill bit rollers

Relevance. One of the problematic elements of roller bit designs is the coupling of the teeth and the roller cutter. It is known that at the first stages of drilling, teeth may fall out, which in turn reduces the efficiency of the bit, and the presence of roller bit elements at the well bottom with a hardness equal to the hardness of the tool itself leads to rapid failure and entails costs associated with emergency repair and maintenance work and troubleshooting. Aim. The article raises issue of increasing the reliability of fixing the hard-alloy structure of roller bits by using intermediate elements made of alloys with thermoelastic phase transformations. Methods. Guided by the principle of efficient use of the shape memory effect and pseudoelasticity (superelasticity) phenomena inherent in this class of materials, the operating conditions of roller bits were analyzed, a design was developed that allows changing the principle of mounting teeth in the roller bit, an optimal titanium nickelide alloy was selected, and tests were conducted that confirmed the positive effect of the proposed method. It is proposed to use transitional locking elements for fixing teeth in the roller bit of a drill bit, made of alloys with thermoelastic phase transformations and having geometric features that allow fixing the teeth with the locking element and the roller due to the geometry, which is a conical or friction-conical connection. Equipment. The following were used in the course of the work: a Shimadzu EDX-8000 X-ray fluorescence analysis device, a Shimadzu XRD-7000 X-ray diffractometer, a RangeVision DIY structured illumination 3D scanner, and an Instron 8801 tensile testing machine. Results and conclusions. Based on the tests, it was concluded that the selected installation method, material, and design will increase the reliability of the hard-alloy teeth fixation and, as a result, increase the penetration per bit, and reduce the risk of an emergency. This, in turn, will help reduce the material and time costs included at the well construction stage.