Boring or penetrating the earth – With magazine for successively moving unconnected – oriented...
Reexamination Certificate
1999-04-23
2001-02-20
Schoeppel, Roger (Department: 3672)
Boring or penetrating the earth
With magazine for successively moving unconnected, oriented...
C175S085000, C175S122000, C414S022510
Reexamination Certificate
active
06189628
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to an earth borer system with a frame incorporating a movable rotary drive for a drill rod assembly consisting of at least two drill rods which can be detachably connected with one another, with a drill rod magazine mounted on the frame, with a release mechanism located on the frame which is provided with a clamping unit that engages in a first drill rod and a break-away unit that engages in one section of the said rotary drive or in a second drill rod, and with at least one transport arm attached to the frame which can move a drill rod released from the drill rod assembly into a standby position in the drill-rod magazine or take a drill rod from its standby position and position it on the drill rod assembly.
BACKGROUND OF THE INVENTION
An earth borer system of this type has been described earlier for instance in the publication EP-A-0 819 820. It includes drill rods which can be screwed together to extend the overall drill rod assembly. For drilling a bore hole, an additional drill rod is moved out of the magazine with the aid of the transport arm, attached to the drill rod assembly, screwed at one end to the rotary drive which for that purpose is retracted into a rearward home position, and screwed with its other end to the back end of the drill rod assembly. In analogous fashion, when upon completion of the drilling operation the drill rod assembly is withdrawn, the drill rods are unscrewed from the rear and the transport arm then moves them back into the magazine.
During the drilling process, the threaded junctions at the rotary drive and between the drill rods usually tend to be tightened beyond the original torque due to the considerable resistance of the subsoil to the mechanical rotation of the drill rod assembly. If both the effective drive torque and the resistance offered by the subsoil are greater than the static friction resistance between the contact surfaces of two drill rods, the threaded connection between these drill rods is tightened further. In the process, the drill rods are turned against the sliding friction resistance of their contact surfaces and are more strongly pressed together in an axial direction.
Given that the static friction resistance is greater than the sliding friction resistance, the torque required to unscrew the rods must be even higher than the torque with which the threaded rod connections are tightened during the drilling operation.
In order to have enough torque for unscrewing the drill rods with a resistive strength greater than the static friction, current systems employ a breakaway unit. In the system disclosed in EP-A-0 819820, a clamping unit is provided at the forward end of the frame, with a breakaway unit mounted immediately behind it.
If, for example, the drill rod assembly is to be extended by the addition of a drill rod, the first step is to stop the rotary drive in a forward retaining position on the frame. Then two hydraulically operated clamping jaws of the clamping unit are pressed against the back end of the rearward drill rod while similar clamping jaws on the breakaway unit grasp a drive chuck on the rotary drive. The clamping jaws of the breakaway unit are attached to a casing which by means of a hydraulic cylinder can be swiveled around the drill axis. For loosening the screw connection the hydraulic cylinder, turning the casing, applies a high torque on the drive chuck in a rotational direction opposite that selected for the drilling operation. This overcomes the static friction on the contact surfaces of the drive chuck and the rearmost drill rod and turns both elements by a certain angle in relation to each other.
The clamping jaws of the breakaway unit are then released and the rotary drive continues to turn the drive chuck with a relatively minor torque, thus completely unscrewing the threaded coupling. The rotary drive subsequently moves away from the forward direction into a rearward home position on the frame and, aided by two transport arms, inserts another drill rod.
The transport arms are multi-articulated gripping arms provided at their respective forward end with a hydraulically operated, more or less crescent-shaped grapple and a counter block. Actuating the hydraulic system allows the grapple to open up and, on grasping a drill rod, to close again. As the drill rod is moved between the rod magazine and the drill rod assembly, it is held between the inner surface of the grapple and the counter block.
A drawback of this prior-art design lies in the fact that the breakaway unit takes up much space so that an earth borer system of this type is unsuitable for drilling sites where there is not much room for accommodating the frame. Moreover, the design and operation of the transport arm in these earlier systems are rather complex and thus prone to breakdowns.
SUMMARY OF THE INVENTION
The object of this invention is a structurally uncomplicated, space-saving earth borer system incorporating a release mechanism.
This is accomplished for an earth borer system of the type referred to above by mounting at least one component assembly of the release mechanism on the transport arm.
In the earth borer system according to this invention, either the clamping unit or the breakaway unit of the release mechanism is mounted on the transport arm. This obviates the need for a separate retaining structure for the concerned components of the unit concerned on the frame of the earth borer system which latter, based on this invention, can now be built with shorter dimensions and can be deployed even under limited space conditions.
According to this invention, the clamping or breakaway unit mounted on the transport arm serves at least two purposes for which in conventional systems two different assemblies are needed. For one, it holds a drill rod while that rod is moved back and forth between the magazine and the drill rod assembly. For another, it permits grasping a drill rod screwed to the drill rod assembly, or the drive chuck of the rotary drive, with enough holding strength that during the breakaway, i.e. unscrewing, process it is not possible for the drill rod or, respectively, the drive chuck to turn while being clamped. If the breakaway unit is integrated into the transport arm, it serves a third purpose by providing the swivel action of this unit around the axis of the drill rod assembly. In other words, this invention combines the essentially conventional functions of multiple assemblies in one single assembly, which considerably simplifies the design of the earth borer system.
Another advantage of the earth borer system according to this invention is the fact that on completion of a drilling operation the drill rod assembly can be dismantled very quickly. After the respective rearward drill rod has been unscrewed, the transport arm will without further movement be in the right position for promptly returning the drill rod to the magazine. This saves the time needed after the breakaway in a conventional system for moving the transport arm to, and engaging, the rearward drill rod.
In a preferred and particularly simple embodiment of the earth borer according to this invention, it is the clamping unit that is attached to the transport arm. The clamping unit has fewer components than the breakaway unit and is thus especially easy to integrate in the transport arm.
It is equally possible, however, to mount the breakaway unit on the transport arm. Integrating the breakaway unit is more complex than attaching the clamping unit since for swiveling the unit around the axis of the drill rod assembly in traditional fashion it is necessary to provide a corresponding bearing and a drive mechanism. However, the advantage of that design variant is that even the more complex and bulky mounting structure for the breakaway unit is now no longer needed on the frame, resulting in particularly significant space savings.
As an especially desirable design feature, the transport arm is bearing-mounted on a pivot extending underneath the drill-rod magazine parallel to the drill axis and connec
McCormick Paulding & Huber LLP
Schoeppel Roger
Terra AG fuer Tiefbautechnik
LandOfFree
Earth borer system with drill-rod changer does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Earth borer system with drill-rod changer, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Earth borer system with drill-rod changer will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2563942