Drilling tool and method for earth drilling

Abstract

The invention relates to a drilling tool for earth drilling with a drill rod element which can be connected to a rotary drive and can be driven in a rotating manner about a drilling axis, a frame-like housing and at least one removal tooth which is supported in a radially adjustable manner in the housing between a retracted position in the housing and an operating position, in which the at least one removal tooth projects radially from the housing. Furthermore, on the drill rod element in the housing a transmission mechanism is arranged, through which a stroke and/or rotational movement of the drill rod element can be translated into a radial movement for radial adjustment of the at least one removal tooth.

Claims

1. A drilling tool for earth drilling comprising: a drill rod element which can be driven in a rotating manner about a drilling axis, a frame-like housing, and at least one removal tooth which is supported in a radially adjustable manner in the housing between a retracted position in the housing and an operating position, in which the at least one removal tooth projects radially from the housing, wherein on the drill rod element in the housing a transmission mechanism is arranged, through which a stroke and/or rotational movement of the drill rod element can be translated into a radial movement for radial adjustment of the at least one removal tooth, on an underside of the housing, removal means for removing ground at a borehole bottom is connected to the housing, the removal means comprises an auger with a drill shaft and at least one drill flight, and the drill shaft is releasably mounted on the underside via a lower connector.

2. The drilling tool according to claim 1, wherein the transmission mechanism has a sliding sleeve which is supported in an axially slidable manner along the drilling axis, in that at least one sliding member is arranged which is supported in a radially adjustable manner in the housing and on which at least one removal tooth is mounted, and in that at least one deflection lever is articulated on the one hand to the sliding sleeve and on the other hand to the sliding member, wherein an axial stroke movement of the sliding sleeve can be translated by the deflection lever into a radial positioning movement of the sliding member.

3. The drilling tool according to claim 1, wherein on an upper side of the housing, an upper connector for a drill rod is provided, and on the underside of the housing, the lower connector for the removal means for removing ground at the borehole bottom is provided.

4. The drilling tool according to claim 3, wherein by way of a fixing element the upper connector is connected to the lower connector in a torque-proof manner and by being axially slidable by a predetermined length of stroke and the axial length of stroke is limited by means of the sliding sleeve.

5. The drilling tool according to claim 1, wherein the transmission mechanism has a rotary member which is supported in a twistable manner about the drilling axis, at least one pivot member is arranged which is supported in a radially pivotable manner on the housing and on which at least one removal tooth is mounted, and at least one pivot lever is articulated on the one hand to the rotary member and on the other hand to the pivot member, wherein a twisting movement of the rotary member can be translated by the pivot lever into a radial positioning movement of the pivot member.

6. The drilling tool according to claim 5, wherein the rotary member can be twisted between a first rotational position, in which the at least one removal tooth is located in the retracted position in the housing, and a second rotational position, in which the removal tooth is located radially outside the housing in the operating position, and the rotary member can be locked in the first rotational position and/or the second rotational position.

7. The drilling tool according to claim 1, wherein on the auger in a lower area at least one hinged tooth is arranged which, when surrounding ground is present, can be swung out from a swung-in retracted position into a radially projecting removal position.

8. A method for producing a bore in the ground, wherein the ground is removed with a drilling tool according to claim 1.

9. The method according to claim 8, wherein initially a cased bore is produced with a support pipe having an inner diameter and an outer diameter up to a first drilling depth, a subsequent bore is continued below the support pipe up to a second drilling depth, wherein the subsequent bore has a drilling diameter corresponding to the inner diameter of the support pipe, and at least in a partial area the drilling diameter of the subsequent bore is enlarged with the drilling tool according to claim 1 up to a drilling diameter which is equal to or larger than the outer diameter of the support pipe.

Description

(1) In the following the invention is described further by way of preferred embodiments shown schematically in the accompanying drawings, wherein show:

(2) FIG. 1: a side view of a drilling tool according to the invention with extended hinged teeth;

(3) FIG. 2: a plan view from below of the drilling tool of FIG. 1;

(4) FIG. 3: a side view of the drilling tool of FIG. 1 with retracted hinged teeth;

(5) FIG. 4: a plan view from below of the drilling tool of FIG. 3;

(6) FIG. 5: a side view of a drilling tool according to the invention with sliding member in the retracted position;

(7) FIG. 6: a plan view from below of the drilling tool of FIG. 5;

(8) FIG. 7: a side view of the drilling tool of FIG. 5 with extended sliding member;

(9) FIG. 8: a plan view from below of the drilling tool of FIG. 7;

(10) FIG. 9: a perspective view of the drilling tool with sliding member;

(11) FIGS. 10 to 12: cross-sectional views of a further drilling tool according to the invention in various radial extended positions of the removal teeth;

(12) FIG. 13: a perspective exploded view concerning the drilling tool of FIGS. 10 to 12 but without transmission mechanism; and

(13) FIG. 14: an assembled illustration of the drilling tool of FIG. 13.

(14) A basic construction of the drilling tool 10 according to the invention, which forms part of a drilling tool unit 5, can be gathered from FIGS. 1 to 4. The drilling tool 10 according to the invention has a frame-like, sleeve-shaped housing 12, the outer diameter of which approximately corresponds to the drilling diameter. The housing 12 has a cover element 18 at its upper side and a base element 16 at its underside. In the circumferential wall of the cylindrical housing 12 two opposite lying openings 20 for removal teeth are arranged. For the sake of clarity, the radially extensible removal teeth of the drilling tool 10 are not shown in FIGS. 1 and 3 and shall be explained below.

(15) At the lower base element 16 of the drilling tool 10 a lower connector 24 in the form of a square Kelly connection is arranged. To form the drilling tool unit 5 a removal means 50 designed as an auger 52 is releasably mounted on the lower connector 24 on the drilling tool 10.

(16) The auger 52 has a drill shaft 54 running coaxially to the drilling axis 7, at the lower end of which a so-called pilot bit 60 is arranged for centering. Extending along the length of the drill shaft 54 is a first drill flight 56 for conveying and receiving removed ground material. In the lower area a second drill flight 58 extends, which enables a symmetrical removal of the ground material by means of arranged cutting teeth 62. In the lower area of the first and second drill flights 56, 58 hinged teeth 64 are arranged in each case, which are arranged on a hinged tooth support 66 that is hinge-supported about a pivot bolt 68. The hinged tooth support 66 can be pivoted between a swung-in retracted position, which is illustrated in FIG. 4, and a swung-out, radially projecting removal position, which is depicted in FIG. 2.

(17) In the unloaded state the hinged tooth support 66 pivots downwards into the retracted position according to FIG. 4. When surrounding ground material is present, the hinged tooth support 66 is pushed outwards into the position according to FIG. 2 in order to enlarge the drilling diameter with respect to the diameter of the first drill flight 56. In this manner, the hinged teeth 64 allow for an enlargement of the drilling diameter even below the drilling tool 10 according to the invention.

(18) To form the drilling tool 10 according to the invention a removal means, illustrated and described in greater detail in conjunction with FIGS. 5 to 9, can be inserted into the housing 12 according to FIGS. 1 and 3.

(19) A first transmission mechanism 30 has a fixing element 32 which is mounted coaxially to the drilling axis 7 on a drill rod element 14. As not shown in detail, the drill rod element 14 has a separate lower element and a second upper drill rod element 14 which is separate from the said lower element but connected thereto in a torque-proof and yet axially slidable manner. On the fixing element 32 two diametrically opposite guide plates 35 are fixed, along which a plate-shaped sliding member 34 is in each case supported in a radially movable manner. For each sliding member 34 two bearing levers 36 are arranged in each case, which are each articulated on the one hand to the fixing element 32 or rather to the guide plate 35 fixed thereon and on the other hand to the sliding member 34.

(20) The retracted position of the sliding member 34, on the exterior of which a plurality of removal teeth 26 is releasably fixed, is shown in FIGS. 5 and 6. In the direction of the lower connector 24 a ring-shaped sliding sleeve 40 is provided, which, in being coaxial to the drilling axis 7, is supported in an axially slidable manner on the drill rod element 14. By pushing the upper connector 22 downwards in the direction of the borehole bottom the sliding sleeve 40 is pushed by the borehole bottom in the direction of the fixing element 32. On the sliding sleeve deflection levers 37 are articulated. During the downward pushing movement, the deflection levers 37 as well as the bearing levers 36 are pivoted into a flatter angular position, which is shown in FIG. 7. As a result of this pivoting movement of the deflection levers 37 the sliding member 34, which is supported in a radially slidable manner, is adjusted radially outwards along the guide plate 35. As illustrated in FIGS. 7 and 8, the removal teeth 26 are in this way adjusted from a smaller first drilling diameter, which is determined by the removal means 50, in the radial outward direction towards the outside of the housing 12 depicted schematically only in FIG. 5. The axial length of stroke of the sliding sleeve 40 is limited by the lower area of the fixing element 32.

(21) A further embodiment of a drilling tool 10 according to the invention with a second transmission mechanism 130 is set out in the following in conjunction with FIGS. 10 to 14.

(22) A second transmission mechanism 130 with a rotary member 132 supported in a rotatable manner about the drilling axis 7 is shown in various operating positions in FIGS. 10 to 12. On the lower connector 24 a stop means with three stops 140 is arranged, which are evenly distributed around the circumference and designed in a segmental manner. Corresponding to this an annular-disk-shaped rotary member 132 is designed which has three drive elements 133 that are also arranged by being offset to each other by 120.

(23) The rotary member 132 is connected in a torque-proof manner to the upper connector 22, as can be gathered from FIG. 13 in particular. All in all, this results in a drill rod element which is connected in a torque-proof manner via the upper connector 22 to the drill rod located above so that a torque transmission can take place via the drive elements 133 and the stops 140 to the drill rod element 14 which is connected in a torque-proof manner to the lower connector 24. Internally arranged spline structures 139 substantially serve for axial guidance.

(24) To form the second transmission mechanism 130 a deflection lever 136 is in each case pivotably articulated to the three drive elements 133. The opposite free end of the deflection lever 136 is connected in an articulated manner to a pivot member 134, on which removal teeth 26 are releasably arranged. The pivot member 134 merges into a bearing lever 137 which is pivotably supported on a bearing block 138 that is fixed on the interior of the sleeve-shaped housing 12.

(25) In FIG. 10 the drilling tool 10 according to the invention with the second transmission mechanism 130 is depicted in the retracted position, in which the removal teeth 26 are arranged inside the housing 12. In this position the drive elements 133 of the rotary member 132 rest in a clockwise direction against the segmental stops 140 that are connected in a torque-proof manner to the housing 12 and the lower connector 24.

(26) By twisting the rotary member 132 counter-clockwise, as shown in FIG. 11, a rotational movement of the drill rod is translated by the second transmission mechanism 130 into a radial outward movement of the removal teeth 26. The twisting of the rotary member 132 causes the deflection levers 136 to be pushed into a more radial position, as illustrated in FIG. 12. As a result, the pivot member 134 with the bearing lever 137 is moved radially outwards so that the removal teeth 26 pass through an opening in the housing 12, not shown here, emerging therefrom radially outwards into an operating position shown in FIG. 12. Accordingly, through a reverse rotational movement the removal teeth 26 can be retracted again.

(27) As can be taken from FIG. 13, in the illustrated drilling tool 10 according to the invention the cylindrical housing 12 has three openings 20 along the circumferential wall of the housing 12 for the passage of the removal teeth 26. The respective stop surfaces of the drive elements 133 of the rotary member 132 and the corresponding stop surfaces of the stops 140 can be sloped so that the rotary member 132, when being in an axially unloaded state in which the drilling tool 10 is freely suspended on a drill rod for example, slides from the axial engaging position, shown in FIG. 14, relatively upwards by a predetermined axial stroke. It is also possible to support the rotary member 132 relative to the housing 12 so that it also stays in the axial engaging position in an axially unloaded state. This allows the drilling tool 10 to be introduced through an inserted support pipe into an already existing bore with a first diameter. Once the drilling tool 10 then rests on the borehole bottom, the upper connector 22 and the lower connector 24 are moved axially towards each other, enabling the rotary member 132 with the drive elements 133 to reach the engaging position shown in FIG. 14.

(28) By transmitting the drilling torque counterclockwise the retracted removal teeth 26 according to FIG. 10 can be rotated into the extended operating position according to FIG. 12. In this way, an enlargement of the drilling diameter can then be implemented below a support pipe in line with the outer diameter of the extended removal teeth 26.

(29) On completion of the bore and transmission of a drilling torque in the clockwise direction, the removal teeth 26 are retracted again by the transmission mechanism 130 from the operating position according to FIG. 12 into the retracted position according to FIG. 10. When lifting the drilling tool 10, the lower connector 24, due to the weight force now applied, is removed axially from the upper connector 22 again, and in the case of sloped drive elements 133 and sloped surfaces on the stops 140 the said drive elements 133 and the sloped surfaces on the stops 140 cause the removal teeth 26 to be retracted again by the transmission mechanism 130 from the operating position according to FIG. 12 into the retracted position according to FIG. 10.