Pryhorovska T. Technological providing of PDC drill bit quality

The thesis is devoted to development of measures to improve PDC drill bit quality by technology study and enhancement of PDC drill bit manufacturing and the use of a systematic approach to quality. Operation conditions, technology and materials used for bit’s body, nipples and cutting elements, machining of conical locking threads, and assembling of PDC drill bits are analized. A mathematical modeling of PDC drill bit–rock interaction to specify kinematic and force options of bit’s operation, studying of manufacturing and assembling error effect on kinematic and force options to specify drill bit test modes in order to specify rational technological options are carried out. Methods of blank manufacturing for bit’s body, technological modes of casting and welding, as well as welding schemes to increase drill bit accuracy are grounded. Methods of blank obtaining for PDC drill bits, technological modes of casting and welding, as well as schemes of welding welds to increase the accuracy of drill bits assembly are substantiated. The influence of technological modes of cutting and hardening of conical threads and technological modes of assembling on PDC drill bit quality are studied. Empirical relations of roughness and technological modes of conical thread grinding of steel and hard alloy are specified. The design of the tool for frictional hardening of threads is improved. Technological equipment for control of conical threads and PDC drill bit geometrical parameters, as well as equipment for bench tests of drill bits are developed. The results of researches are implemented in manufacture and educational process.