Mining or in situ disintegration of hard material – Hard material disintegrating machines – Rotary cutter head with advance direction coincident or...
Patent
1992-03-17
1993-10-26
Bagnell, David J.
Mining or in situ disintegration of hard material
Hard material disintegrating machines
Rotary cutter head with advance direction coincident or...
299 31, 405141, E21D 908
Patent
active
052559602
DESCRIPTION:
BRIEF SUMMARY
The invention relates to a tunnel drilling apparatus provided with a working tool at drill head and to a method by means of which the drill waste is removed from the working tool inside the protecting pipe.
Previously is known tunnel drilling apparatus with one working tool a.o. from the U.S. Pat. No. 4,122,683. A working drill head that rotates on cutting the tunnel front wall is introduced in the publication. The excavated material is shifted into the protecting tube of the drill head and further to the rear end of the apparatus. The apparatus has a plurality of abutments immobilized against the tunnel walls enabling adjustment of the drilling direciton by providing support from the tunnel walls to the protecting tube and turning the tool or the mobile part of the tool head in desired direction for instance by means of turning cylinders.
The U.S. Pat. No. 2,919,121 introduces an apparatus with one tunnel drilling tool by means of which excavated material is shifted into a rotating tube. Outside this tube there is another tube, the actual protecting tube enveloping the drill head. This tube is supported by wheels and expanding ring segments against the tunnel walls and adjustment of the drilling direction is provided with these wheels and ring segments.
The disadvantage of the above described solutions is characterized in that the excavated material has access to the bottom of the tunnel during working because of the placement of bit components in applied tools with respect to the protecting tube. A space is left open between the bits and the protecting tube, where excavated material simply piles up. It is complicated to force the material between the protecting tube and the driving tube and even not quite possible in driving a tunnel in unbroken rock. In these cases, a certain quantity of drill waste always remains in the tunnel, which means hindrance to the drill head alignment, since control of driving is effected through leaning on the tunnel walls. Then disturbing drill waste piles up especially in the lower parts of the tunnel and wedges itself between the protecting tube and the tunnel.
The method and apparatus according to this invention provide a crucial improvment of said disadvantages. In order to put this into practice, the method and apparatus are characterized in what has been described in the enclosed patent claims.
It can be considered the main advantage of the invention that the drill head can force itself through to the inner surface of the reliably waste-free tunnel which makes it possible to use a simple direct forward-driving drill head without any kind of control equipment. Furthermore, a lap joint prevents access of loose soil from tunnel upper surface to striking bit neck portion, where it would cause interruption of drill bit stroke in no time at all. Advantageously, the method of this invention is applicable to tunnels with small-sized diameters, preferably to ones with diameters under 800 mm. In addition, the advantage of this invention is increased since it is especially difficult to furnish small-diameter drill heads with control equipment.
In the following the invention is described in detail with reference to the enclosed drawing.
FIG. 1 is a drill head with a tool.
FIG. 2 is a drilling apparatus resting on the tunnel bottom firmly supported by the steering tunnel walls.
The tool (4) in FIG. 1 comprises a bore bit holder (51) with openings (2), along which the drill waste is conveyed by compressed air from the front end of bit 1 to the protecting tubes (3,7). Compressed air enters the tool along a hose (8) and at least a part of it is conducted to the bit front end to convey drill waste. Between the drill bit holder and its protecting tube (3), there is a lap joint to prevent access of drill waste to the outside of the protecting tube. Arrangement of position and direction of openings (2) makes it possible to provide an ejector effect in the lap joint so that even drill waste, which may have somehow passed the drill bit, is sucked up into the protecting tube. The collar ring
REFERENCES:
patent: 2919121 (1959-12-01), Ruth
patent: 3005627 (1961-10-01), Tinlin
patent: 4122683 (1978-10-01), Follert et al.
patent: 4534676 (1985-08-01), Saito
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