Boring or penetrating the earth – With below-ground tool drive prime mover – Discharge passage for motive fluid directed toward bore...
Patent
1995-09-29
1997-01-07
Novosad, Stephen J.
Boring or penetrating the earth
With below-ground tool drive prime mover
Discharge passage for motive fluid directed toward bore...
175215, 175393, 175418, 2851331, E21B 2112, E21B 414, E21B 1718, E21B 1038
Patent
active
055907253
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The invention pertains to a drilling column with an air duct for the addition of compressed air to a sledgehammer drilling head, which drilling head has a percussion drilling crown on its lower end and a central connector with a compressed air feed opening on its upper end.
During use of sledgehammer drilling heads, the sledgehammer driven by compressed air is located at the deepest point in the drill hole. The compressed air required for the hammering process is fed through the drilling column consisting of a simple drilling pipe. The compressed air exits from the percussion drilling crown and flows towards the gound surface in the space between the drilled cavity wall and the drill column, whereby the drilled material is forced to the surface.
In order to reach and maintain the required flow velocity for the maintenance of the conveying effect, very high compressed air volumes must be fed. For example, in a drilling diameter of approximately 380 mm and a drill pipe diameter of approximately 150 mm, approximately 25-30 m.sup.3 of compressed air must be applied; the required flow velocity of approximately 30 m/sec in the annulus between the drill pipe and the drilled column wall is thereby accomplished. To achieve this, compressors must work very hard, and they experience a very high energy usage of for example 100 liters of diesel fuel per hour. The operation of diesel motors to drive the compressors represent an elevated environmental load.
The task of the invention is thus to institute a drilling column with a sledgehammer drill head of the type named above such that a significant reduction of the energy usage is accomplished while using conventional sledgehammer drill heads.
SUMMARY OF THE INVENTION
This task is solved according to the invention by constructing the drilling column out of a drill pipe with a central feed channel, around which the air duct is located. Between the lower end of the drill pipe and the connector of the sledgehammer drilling head, a coupling piece is installed which has a discharge channel section which rims from the central discharge channel of the drill pipe to a lateral inlet port and which also has at least one air duct section running from the air duct of the drill pipe to the central connector of the sledgehammer drill head. In proximity to the lateral inlet port of the coupling piece, a skirt open to the bottom is installed eccentrically with respect to the drilling head.
The use of a well-known two-way drill pipe makes it possible to use the central conveying channel of the drill pipe for the removal of the drilled material by means of the supplied compressed air. Since the flow cross section of this central conveying channel is significantly smaller than that of the annulus between the drill pipe and the drill hole wall, a sufficient flow velocity required for the conveyance process is achieved with significantly smaller compressed air volumes. For example, the compressed air volume, and thereby the energy usage, can be reduced to half of that compared to the conventional process. Thereby, a significant protection of the environment can be achieved.
The compressed air required for the operation of the sledgehammer drill head is fed downwards inside the coupling piece to the central connector of the sledgehammer drill head from the air duct discharging from the perimeter. In this way, the sledgehammer drill head is located at the center of the drill column, which is required on the basis of the energy direction. Moreover, the compressed air addition is carded out centrally to the connector so that physical modifications to the sledgehammer drill head do not need to be made. Therefore conventional sledgehammer drill heads can be used without modification.
The skirt installed air-fight on the connector, which surrounds the drive portion of the sledgehammer drill head, is open to the bottom primarily in the region beneath the lateral inlet port of the coupling piece, in order to take up the drilled material immediately above the percussion
REFERENCES:
patent: 3151690 (1964-10-01), Grable
patent: 3439757 (1969-04-01), Elenburg
patent: 3596720 (1971-08-01), Elenburg
patent: 4274497 (1981-06-01), Willis et al.
patent: 4509606 (1985-04-01), Willis
patent: 4630691 (1986-12-01), Hooper
patent: 5209262 (1993-05-01), Carow et al.
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