초록 ▼

A locking device has a lower concave housing suitable to receive and hold an upper end of an element to be attached to a drill stem. The housing forms a conical surface. A number of blocks slides along the conical surface. Each block has an outside sliding surface that is parallel to the conical sur

A locking device has a lower concave housing suitable to receive and hold an upper end of an element to be attached to a drill stem. The housing forms a conical surface. A number of blocks slides along the conical surface. Each block has an outside sliding surface that is parallel to the conical surface and has an inside surface suitable to engage the elements to be held. The blocks are mounted to slide along the conical surface. The blocks are moveable from a first, free position in which the blocks are pushed toward the lower, outside surface of the conical surface to a second, locked position in which the blocks are radially clamped against the element to be hold.

대표청구항 ▼

[ What is claimed is:] [1.] A locking device to screw and to unscrew elements having threaded couplings and belonging to a drill stem, said device being suitable for use in drill rigs comprising a rotating head suitable to make said drill stem rotate about a substantially vertical axis and slide alo

[ What is claimed is:] [1.] A locking device to screw and to unscrew elements having threaded couplings and belonging to a drill stem, said device being suitable for use in drill rigs comprising a rotating head suitable to make said drill stem rotate about a substantially vertical axis and slide along said axis,wherein the device comprises a lower concave housing suitable to receive and to hold the upper end of an element to be screwed or unscrewed into the drill stem in the drill hole,wherein said concave housing forms an envelope of surfaces divergent in a downward and outward direction in order to allow a plurality of blocks to slide along said envelope of surfaces, wherein each of said blocks has an outside sliding surface, parallel and cooperating with said envelope of surfaces, and an inside surface suitable to engage the element to be held; the blocks are mounted in order to slide along said envelope of surfaces,wherein said inner surface, having a cylindric shape that is congruent with the lateral cylindric surface of the upper end of the element of the drill stem, cooperates with the horizontal surface of a flange suitable to be pushed against an upper edge of said element, andwherein said blocks are moveable between a first free configuration, with the locking device in its lifted position, in which the blocks are pushed by elastic means towards a lower, outside portion of said envelope of surfaces, anda second locking configuration, with the locking device positioned on the element to be held, wherein the blocks are radially clamped against the upper end of said element.