Method of producing thin, hard coating

#1. Field of the Invention

#This invention pertains to the manufacture of rolling cone rock bits. More specifically, this invention pertains to a manufacturing step to be used for the enhancement of the surfaces of the seals and the bearings in a rolling cone rock bit.

#Rolling cone rock bits are used to bore holes and wells into hard rock for the exploration and production of mineral resources. They commonly operate under a column of abrasive fluid which is used to cool the bit and flush cuttings from the bottom of the hole.

#FIG. 1 is a perspective view of a typical three cone rotary rock bit.

#FIG. 2 illustrates part of a rotary cone rock bit, showing a journal and a sectioned rotary cutter cone mounted thereon.

#Turning now to FIG. 1, a rock bit, generally designated as 10, consists of body 13, an upper pin end 12 and a lower journal end 14. Rotary cones 16 each support a multiplicity of cutting teeth 17 and are mounted on journals (not shown). The journals are cantilevered from end 14 of rock bit body 13 and directed radially inward. One or more jet nozzles 18 direct a flow of fluid toward the spaces between adjacent cones 16.

#In FIG. 2, cone 16 has been sectioned to reveal a journal, generally designated as 30, in enlarged detail. Journal 30 is supported cantilevered from the journal end 14 of bit body 13. Major features of the journal are a sealing surface 25, a journal bearing surface 20, a spindle bearing surface 28, and a thrust bearing surface 26. A circular ball race (not shown) partially houses ball bearings 31 which are used for retaining the cone upon the journal and for resisting back thrust. The cone 16 has features within its bore which complement the journal. Groove-shaped seal gland 24 houses seal 22 adjacent journal bearing surface 32. Ball race 33 partially houses ball bearings 31. The cone bore is reduced to provide spindle bearing surface 26 and reduces once more to provide the blind pocket in which is housed thrust button bearing element 34.

#In a modified physical vapor deposition process, a selected coating will be thinly and uniformly deposited upon at least selected areas of otherwise finished manufactured parts. This coating is an engineering ceramic comprised of at least one element selected from a list consisting of Ti, Hf, Zr, Nb, Ta, W, B, Al, Co, and Cr, combined with at least one element selected from a list consisting of O, N, and C.