Drill collar with thread connections

Claim 1

A drill collar for a rotary drill string, comprising a drill collar body member, a connection member at one end of said body member having a threaded end adapted for attachment to a companion threaded end of an adjacent portion of the rotary drill string, a first of said members including a pin portion having a conical outer surface, a second of said members including a box portion having a conical inner surface and adapted to receive said pin portion, said conical inner surface matching the configuration of said conical outer surface, one of said members having an external transverse shoulder near the base of the conical outer surface of said pin portion, the end of said box portion confronting said shoulder, a wear sleeve mounted on said pin portion between said shoulder and said end of said box portion, said wear sleeve being engageable by said shoulder and said end of said box portion, said sleeve having a conical inner surface corresponding to and in contact with said conical outer surface, means on one of said members for directing fluid under pressure to the region between said box portion inner surface and conical outer surface to expand said box portion, means on said sleeve for directing fluid under pressure to the region between said sleeve inner surface and conical outer surface to expand said sleeve, whereby expansion of said box portion and sleeve enables said pin portion to be moved relatively longitudinally along said box portion and sleeve to engage said end of said box portion with said sleeve and engage said sleeve with said shoulder to effect securing of said sleeve and box portion to said pin portion by shrink-fit frictional engagement between said sleeve and box portion inner surfaces and conical outer surface upon relieving of the fluid pressure in the regions between said sleeve and box portion inner surfaces and conical outer surface.