FIELD: drilling technology.
SUBSTANCE: device has body with stepped cylindrical inner surface. Inside the body force shelves are made. In the body wedges with screw-thread dies, inserts under wedges and localizer are placed. Also provided are under-rotor drive for wedges and a cross-piece for chisels which is mounted with wedges removed and inserts with localizer between force shelves onto support between steps of cylindrical inner surface. Above cylindrical inner surface of body in its upper portion inner radial force shelves are made. Toothed surface of screw-thread dies and die-less wedges is placed below line passing through upper point of slanting flat support of wedges at angle perpendicular to said flat support plus friction angle of surfaces of wedge and insert. Screw-thread die in wedge is supported by two-step flat transverse support in radial direction and by axial support in upper portion of wedge under slit for suspension bracket, with pin and bolt fixings of screw-thread die under axial support. Space between teeth of adjacent wedges while holding a pipe by wedges is no more than 0.9-1.1 of thickness of wall of held pipe. Die-less wedges in upper portion are placed above force shelves of body made between screw-thread die and crosspiece for chisels with vertical space between shelves of wedges and force shelves in body while holding a pipe, matching drive before engagement of wedges, and the remaining portion of wedges is placed between force shelves inside the body. Space between lower portion of supporting surface of wedge and localizer while holding a pipe matches drive before engagement of wedges. Displacement of pipe in pass-through aperture of localizer is no greater than 0.35-0.5 of width of supporting surface of wedges.
EFFECT: excluded slipping of pipes while being held by wedges, greatly increased life span of screw-thread dies, lower force loads in pipe between wedges, higher carrying capacity of die wedges and whole device, assured even distribution of pressure of wedges along the pipe, backup drive of wedges guaranteed for holding of all main type-dimensions of pipes in limited pass-through aperture of rotor.
3 cl, 11 dwg
