Boring or penetrating the earth – Bit or bit element – Rolling cutter bit or rolling cutter bit element
Patent
1983-03-08
1985-10-29
Novosad, Stephen J.
Boring or penetrating the earth
Bit or bit element
Rolling cutter bit or rolling cutter bit element
175373, 175400, 175106, 175291, E21B 1018
Patent
active
045496145
DESCRIPTION:
BRIEF SUMMARY
The present invention concerns a drilling device comprising a drilling head equipped with a rotating body through which runs a duct for supplying air and water or either drilling fluid and bearing at least one rotating cutting element.
Existing drilling devices comprising a drilling head equipped with three cutting elements markedly conical or in the shape of a truncated cone have been known and used since the 'thirties. The three theoretical tops of the cutting elements coincide with a point of the rotating shaft of the drilling head. The side of each cone is fitted with teeth of a size and sharpness appropriate to the type of ground to be drilled. Each cone is mounted on the drilling head in such a way that it rests on the ground following one of its generants and the teeth of one cone fit into the spaces between the teeth of the adjacent cone. The action of the three cones on the ground is the same as that of three rollers fitted with teeth. Each cone is retained radially by a shaft on which is mounted a ball bearing retaining the cone axially. During drilling, especially in the case of rocky ground, great pressure must be exerted to break the rock and subsequently cut it up and clear it away. With the three cones working along one of their generants, the working surface is large and great weight must be brought to bear on the drilling head to obtain the necessary pressure. The ground undergoes great compression which has the effect of breaking the rock, especially in the case of a rock cracked, over a radially more extensive surface than that of the drilling, thus creating an irregular drilling profile and an unstable wall.
The continuous injection of any drilling fluid into the bottom of the hole ensures the evacuation of the excavated ground and rock cut up by the three cones. The diameter of the surface of the bottom of the hole is approximately the same as the diameter of the drilling head and the evacuation of excavated ground is only ensured if their dimensions allow them to pass between the periphery of the head and the wall of the hole. The pieces of rock must therefore be broken up until they can pass between the wall of the hole and the periphery of the drilling head, slowing up the progress of the drilling and allowing fine particles of the excavated rock conveyed by the drilling fluid to reach the drill bit bearings, so destroying them.
Replacing a cone in case of breakdown takes a long time because the bearing must be removed to take off the cone.
The construction of a drilling head equipped with a semisphere fixed to a shaft almost perpendicular to the axis of the rotating body has already been suggested. The circumference of the disc is fitted with means to cut and profile the wall while the spherical surface which rests against the bottom of the hole to break by compression the bottom and the pieces cut out by the edge of the disc.
The invention aims to make it possible to produce a drilling device operating at low power, the cutting element being easily mounted on the drilling head and enabling the evacuation of larger pieces of debris.
The drilling device according to the invention is characterized by the fact that the cutting element is a disc provided with at least a ring-shaped cutting part and that the rotating body bears, on the side opposite to that carrying the rotating shaft of the disc, at least one counter-reacting element and placed so that the said element rests against the drilling wall to centre the drilling head by compensating for the radial component of the reaction of the ground on the disc and to strengthen the wall.
The counter-reacting element serves to stabilize the drill bit which could tend to oscillate around the drill shaft and to slightly offset the lower point of the cutting surface in relation to the drilling axis.
Because the disc acts on the wall to be cut by a ring-shaped surface equipped with cutting means, the action of the disc is to shear the wall and not to compress it in order to obtain its disintegration. There is certainly a slight compression b
REFERENCES:
patent: 1124243 (1915-01-01), Hughes
patent: 1152151 (1915-08-01), Decker
patent: 2151545 (1939-03-01), Zublin
Kaalstad Oscar W.
Reid Neil G.
Engtech SA
Goodwin Michael A.
Novosad Stephen J.
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