Tula State University, Tula, Russia

A. B. Zhabin, Doctor of Engineering Sciences, Professor, zhabin.tula@mail.ru

Siberian State Industrial University, Novokuznetsk, Russia

V. A. Korneev, Candidate of Engineering Sciences, Associate Professor

Gorny Instrument, Novokuznetsk, Russia

V. V. Kalinin, Design Engineer

EvrazTekhnika, Novokuznetsk, Russia

I. I. Kulebakin, Dedicated Information System Supervision Specialist

Kuznetskbusinessbank, Novosibirsk, Russia

D. I. Korneeva, Cat I Economist

During rotary drilling, cutters experience multiple loading, including the major mechanical, abrasive and thermal loads. The tool degradation shows up, for the first turn, at cutting inserts, which makes the choice of reinforcement materials and geometry of contact surfaces the most critical problem in the mining machine engineering. This article describes the studies on heating of an insert blade and a brazing insert–holder joint during operation of a drilling cutter. The research was carried out on a lab-scale drilling testing machine with simulation of drilling modes by Fletcher system without flushing. For evaluating the tool temperature drop during pull out from borehole, the mathematical modeling was performed in T-FLEX CAD. The tools studied were two-wing PDC cutters with a diameter of 30 mm. Drilling was carried out without flushing, with removal of chips via a hollow rod SHP-22 where chips entered by gravity. The cutting thrust was 9.8 kN, and the rotation speed of the drill string was 335 min^-1. The penetration depth reached 800 mm. The results show that during drilling, the heating temperatures of the insert blade and brazing joint reach 359 °C and 355 °C, respectively. During pull out of the drilling string from the hole, the heat temperature of the brazing joint and insert blades dropped by 54 °C and 60 °C, respectively. As the heating temperature of the cutting inserts grows, the hardness of their diamond layer decreases. Alongside with this, in the blade inserts, stresses appear due to the different temperature coefficients of linear expansion in the steel-and-carbide binding phase and in the diamond master phase. So, removal of chips by flushing-out of holes contributes to the higher rate cooling of the tool than in the case of blow-down. In this connection, the tool life is longer in operation with the hydraulic cleaning of holes as compared with the airaided removal of drilling chips.
The study was supported by the Siberian State Industrial University, Contract No. 115/2025/UNI as of April 1, 2025.

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