Improvement of drilling cutter design

Abstract

The article describes the design of drilling cutters most commonly used in coal mines in Russia. The area of their application is given versus the type of a drilling machine and hardness of rocks. The implemented research aimed at finding the causes of failure of drilling cutters shows the types of breakdowns of drilling cutters and their causes. A review of the recommendations and modern engineering solutions on increase in the life of rotary drilling tools is given. Percentages of the cutter failure causes over the period from 2010 to 2014 are presented. The main failure cause of cutters is found to be the blunting of the blades of tungsten-cobalt cutting plates. The studies conducted earlier by the authors of the article indicate the possibility of extending the life of a drilling tool by reinforcing its cutting plates with superhard composite materials. In this connection, the use of composites based on cubic boron nitride has been proposed for creating cutting inserts for drilling cutters. The article also describes the study of rock drilling rates with various cutters mounted on hydraulic and pneumatic drilling machines. The obtained information can be used when planning drilling in coal mines. It is shown that the highest drilling rate can be achieved with hydraulic drilling machines equipped with triple cutters. It is found that with the growth of rock hardness on the scale of Professor M. M. Protodyakonov, reduction in the drilling rate of a hydraulic drilling rig with a three-blade cutter occurs more intensively than with a pneumatic drilling rig with a two-blade cutter. It is revealed that at the rock hardness of 10 on the Protodyakonov scale, drilling rates of different design cutters differ slightly. The study was supported by the President of the Russian Federation, Grant for Young Candidates of Sciences—MK-6689.2018.8.