Boring or penetrating the earth – Processes – Boring horizontal bores
Patent
1992-03-17
1994-05-31
Britts, Ramon S.
Boring or penetrating the earth
Processes
Boring horizontal bores
175171, 175323, E21B 720
Patent
active
053160924
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to a method and apparatus for drilling a tunnel, wherein there are two independent forces; the one driving the protecting tube and the other driving the drilling apparatus by means of a rotating spiral tube.
2. Description of the Prior Art
A previously known drilling apparatus as described in applicant's former patent application No. FI-891706, is one in which the protecting tube is forced into the excavated drilling head advances through the tunnel portion as the tunnel. Also the force for the tool in the drilling head is transmitted over the protecting tube. The conveying tube rests against the inner surface of the protecting tube and moves forward along with the protecting tube. There is a thrust bearing in the drill head, and so the force over the protecting tube is transmitted entirely through the thrust bearing as a force for the tool forward drive.
U.S. Pat. No. 2,669,441 the tools and the thrust bearing are in the working pit. No protecting tube is driven into the tunnel but the force into the drill head is simply brought forward by a rotating conveyor pipe.
The disadvantage of the prior art devices is lack of control of the force. On driving the drill head forward with the protecting tube, the required force changes as the length of the protecting tube grows and because of friction from different soil types. This means that the farther the drilling advances the more the information about the impact of tool forces against he front wall of the tunnel diminishes and possible obstacles cannot then be detected. Therefore, the risk of tool damage is great. In U.S. Pat. No. 2,669,441 drilling is possible only in rock or soil that needs no protecting tube to support the tunnel.
SUMMARY OF THE INVENTION
By means of the method according to this invention a crucial improvement of the said disadvantages has been achieved. In order to put this into practice, the method and apparatus of this invention are characterized in what has been presented in the patent claims.
It can be considered the main advantage of this invention that the tool driving force, which is smaller than the force driving the protecting tube, is separated as an independent and easily adjustable force. When the force has been separated by means of a hydraulic cylinder, which can yield because of pressure adjustment while functioning also as thrust bearing and therefore move freely in the longitudinal direction of the drilling apparatus, the tool hitting an obstacle can be detected immediately as rise of pressure in the hydraulic system.
BRIEF DESCRIPTION OF THE DRAWINGS
In the following the invention is more closely described with reference to the enclosed drawings where
FIG. 1 is a driving and rotating unit in the working pit where the hydraulic cylinder functions as thrust bearing.
FIG. 2 is an optical driving and rotating unit placed in the working pit where the hydraulic cylinder functions as thrust bearing.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
The solution in FIG. 1 provides a hydraulic cylinder (23) which functions as a thrust bearing comprised of a piston (24) and a piston rod (26). The piston rod (26) is a pipe through which the hydraulic pressure hoses (30,29) can be taken to the piston (24) and conduct the pressure fluid to the chamber space on both sides of the piston. The cylinder (23) is closed with a threaded ring flange (35). The cylinder (23) itself is a rotating drumlike part. The rotation is transmitted from the fluid motor (16) by means of a gear (25) which is attached to the cylinder (23) with a broad gear (31). The pressure fluid enters the fluid motor (16) along the hoses (20). The cylinder (23) is encircled with an immobile annular part (22), inside of which the cylinder (23) can rotate and also slide lengthwise. Part (22) is fixed to the actual frame (27) that conduits the driving force. The connecting surface between cylinder (23) and part (22) is a bearing area which also comprises an annular chamber space (32) into which compre
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patent: 2319512 (1943-05-01), Parrish
patent: 2669441 (1970-04-01), Castanoli et al.
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patent: 3851716 (1974-12-01), Barnes
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patent: 3917010 (1975-11-01), Fink
patent: 3945443 (1976-03-01), Barnes
patent: 4091631 (1978-05-01), Cherrington
patent: 4226477 (1980-10-01), Capoccia
Britts Ramon S.
Tsay Frank S.
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