Boring or penetrating the earth – With above-ground means to impact an earth-penetrating means
Reexamination Certificate
1999-04-22
2001-03-20
Pezzuto, Robert E. (Department: 3671)
Boring or penetrating the earth
With above-ground means to impact an earth-penetrating means
C173S105000
Reexamination Certificate
active
06202763
ABSTRACT:
BACKGROUND OF THE INVENTION
The invention relates to a drilling apparatus having spun-up outer pipes and spun-up inner pipes, which can be driven by a rotary drive and a rotary impact drive, the outer pipe being adapted for coupling at one of shank ends projecting on both sides of the rotary drive and being engageable with a striker that is mounted on the inner pipe for axial movement therewith.
Drilling apparatuses of this type are used in special underground construction, in mining and earth-moving operations and in the construction industry. They are used to form holes in rocks for insertion and fastening of anchors when various rocks are used as a foundation for construction. Such drilling apparatuses have an outer pipe string and an inner pipe string, each of the outer pipes and inner pipes having threads for making up the pipe strings. When flushing fluid is caused to pass through the interior of the inner pipes from the flushing head to the core drill bit, the flushing fluid filled with cuttings is removed to the ground surface through the space defined between the outer pipes and the inner pipes. Normally, the inner pipe is driven by a rotary impact drive, and the outer pipe is driven by a rotary drive only. This can be a problem, especially in dealing with hard rock. Accordingly, as described in DE-PS 35 03 893, the rotary impact drive for the inner string is also used to act upon the rear end of the outer string. For that purpose, the inner string has an annular shoulder for the impact engagement with the outer string. The impact mechanism can be pulled back axially with the ring shoulder, whereby the drilling apparatus can work with the outer pipes being driven for rotation only. To resolve this problem, the design according to DE-PS 35 03 893 involves gear teeth provided at the end face of the annular shoulder and at the end of the outer pipe to form a rotary coupling between the outer pipes and the inner pipes. This gearing causes another problem relating to strong wear of the annular shoulder and also of the end portions of the outer pipe, so such drilling apparatuses cannot be used for a long time. It should be also borne in mind that the annular shoulder that comes to engage the end portion of the outer pipe is also rotated together with the inner pipes. The two rotary systems are positively interconnected through the gearing.
The invention is based on the problem of providing a drilling apparatus having a design in which an outer pipe can have a rotary or a rotary percussion connected to, and driven by, the drilling apparatus.
SUMMARY OF THE INVENTION
This problem is resolved, according to the invention, by the fact that the shank end is provided with a compensation ring on the rotary impact side, which has the hardness that is lower than that of the material of the pipe and striker and/or corresponds to that of the end portion of the shank end and has a form and/or surfaces to compensate for the applied forces.
Using an annular shoulder for the striker to engage the end portion of the shank end is known from DE-PS 35 03 893. In this particular case, a compensation ring is provided between two engageable parts, namely the end portion of the shank end and the striker, and is used for compensation between the rotating impact part and the striking impact part to avoid premature overloading of, or damage to, both the striker and the end portion. With the proper construction and material for the compensation ring, even when the compensation ring is worn, the compensation ring is still capable of transmitting the applied forces and blows. This is ensured by a particular configuration and surface, as well as the general form of the compensation ring, that does not generally require any special material of treatment regardless of whether the drilling apparatus is used for a rotary or rotary impact drive of the outer pipe. Only when, for any reason, extreme stresses occur under an overload, is it required that the compensation ring be replaced when it shows signs of damage.
In a preferred embodiment of the invention, the compensation ring has, on one side, a surface corresponding to the adjacent end portion of the shank end, which is three-dimensionally curved. This ensures the alignment of the compensation ring on the one side and the shank end on the other side without any need for exact guidance of both parts. At the same time, such a compensation ring and an appropriately designed shank end ensure the central application of forces to the outer pipe in the case of the offset application of forces. This ensures reliable compensation by means of the compensation ring.
It is especially preferred, according to the invention, that the compensation ring have surfaces on both sides surface corresponding to the adjacent end portions of the shank ends, which are three-dimensionally curved, and it is understood that the shank end on the one side and the striker on the other side have surfaces that are respectively curved. The compensation ring has its curved surface or surfaces on the respectively curved shank end at the respectively curved striker. As will become clear from the description, in this manner the compensation ring will always remain in an optimum position without any additional adjustment or control devices being required.
The compensation ring should be preferably installed at the shank end in such a manner that the compensation ring made as a loose part remains at the shank end when the impact drive with the striker is pulled back. In order to rule out slip, tilt, and the like, it is provided, according to the invention, that the shank end has a casing supported by the rotary drive motor encloses the compensation ring. It is preferred for the sake of simplicity to provide the casing with projections that are designed to fix the compensation ring, with the striker having a respectively smaller diameter to be received within the casing in such a manner as to be in contact with the respective surface of the compensation ring during the rotary percussion operation.
It should be also noted that with the rotary percussion mode for the outer pipe described herein, the inner pipe and the striker of the rotary impact drive rotate simultaneously, because the rotary impact drive is connected to the inner pipe or is made integrally therewith. To avoid damage to the smooth surfaces, which can be in contact with the drilling fluid, according to the invention, the casing has lubrication holes opposite to the curved surfaces of the compensation ring. Grease or the like can be put into these lubrication holes at regular intervals, e.g., before starting operation or on an as-needed basis so as to ensure lubrication of both surfaces of the compensation ring and the mating faces of the shank end and the striker.
To remove the grease moving under pressure on both sides sliding over each other and, more specifically, to facilitate insertion of the inner pipe through the compensation ring during assembly, it is preferred that the compensation ring have a central hole of a diameter that is larger than the diameter of the inner pipe. It is preferred that this central hole have a chamfer to reduce damage caused by blows of the striker in this area. It is also preferred that the striker also have the chamfered edge in this area, and the opposite side of the central hole may also have a chamfer.
To ensure guidance for the compensation ring in the casing on the one hand and to allow the compensation ring to reciprocate over the full range over the surfaces of the shank end and the striker, the outer edges of the compensation ring are rounded. In this manner, the compensation ring has rounded edges all around to ensure good support for the compensation ring between the faces of the shank end and the striker.
The striker is mainly a part of the inner pipe; it is appropriately driven by the rotary impact mechanism and can transmit the impact energy to the outer pipe string. To facilitate make-and-break operations and to optimize installation, according to the invention, the striker is made
Gude Dieter
Maus Josef
Creighton Wray James
Deilmann-Haniel Maschinin-und Stahlbau
Narasimhan Meera P.
Pezzuto Robert E.
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