Drill head and device with a sliding contact electrical connection for drilling a bore in the ground

Abstract

The invention relates to a drill head and a device for drilling a bore in the ground, the drill head having a first unit coupleable with an inner drill pipe of a double drill pipe assembly and a second unit coupleable with the outer drill pipe of the double drill pipe assembly. By means of the inner drill pipe the first unit is rotatable about an axis of rotation relative to the second unit which is drivable by means of the outer drill pipe. The drill head has a sliding contact arrangement for establishing an electrical connection between the first unit and the second unit.

Claims

1. A drill head for drilling a bore in the ground, comprising a first unit coupleable with an inner drill pipe of a double drill pipe assembly; a second unit coupleable with an outer drill pipe of the double drill pipe assembly, wherein (by means of the inner drill pipe) the first unit is rotatable about an axis of rotation relative to the second unit which is drivable by means of the outer drill pipe; and a sliding contact arrangement for establishing an electrical connection between the first unit and the second unit, wherein the sliding contact arrangement is releasably and re-connectably connected to at least one of the first unit and the second unit; wherein the sliding contact arrangement comprises at least two sliding contacts for establishing an electrical connection between the first unit and the second unit; wherein the two sliding contacts each comprise a first contact element and a second contact element; wherein the two first contact elements form a first contact arrangement and wherein the two second contact elements form a second contact arrangement; and wherein the first contact arrangement is releasably connected to the first unit and/or the second contact arrangement is releasably connected to the second unit.

2. The drill head according to claim 1, wherein the sliding contact arrangement comprises at least a first contact element connected to the first unit in a rotationally fixed manner; and a second contact element connected to the second unit in a rotationally fixed manner; and wherein the first contact element and the second contact element form a sliding contact.

3. The drill head according to claim 2, wherein one of the first and second contact elements is designed as at least one slip ring formed on a one-piece base body and the respective other of the first and second contact elements is designed as a brush arrangement which is complementary to the slip ring, wherein the base body with the slip ring together with the brush arrangement forms a structural unit which is releasably and re-connectably connected to at least one of the first and the second unit.

4. The drill head according to claim 1, wherein the second unit has a sealed cover through which at least one component of the sliding contact arrangement is insertable into the drill head and removable therefrom when the cover is open.

5. The drill head according to claim 1, wherein the second unit comprises an outer casing of the drill head; and the first unit comprises an inner drill pipe adapter with which the inner drill pipe is connectable, wherein at least a first contact element of the sliding contact arrangement is connected to the inner drill pipe adapter in a rotationally fixed manner and wherein at least a second contact element of the sliding contact arrangement is connected to the second unit in a rotationally fixed manner.

6. The drill head according to claim 1, wherein an electrical device is arranged in a sealed closable opening of the second unit and one of the electrical device is electrically connected to the second contact element and the second contact arrangement via a cable.

7. The drill head according to claim 6, wherein the electrical device comprises a transmitter for locating by means of a locating device arranged at the earth's surface, a sensor for determining the position of the drill head, a sensor for determining the inclination and/or a sensor for determining the rotary position of the drill head.

8. The drill head according to claim 1, wherein via the sliding contact arrangement an electrical device arranged in the second unit is supplied with energy, data and/or signals that are transmitted to the electrical device and/or data and/or signals are transmittable from the electrical device.

9. The drill head according to claim 1, wherein the drill head comprises at least one seal, and the first unit comprises an inner drill pipe adapter, wherein the seal keeps away dirt present at the drill pipe-side end of the inner drill pipe adapter and/or liquid present at the drill pipe-side end of the inner drill pipe adapter from the sliding contact arrangement.

10. The drill head according to claim 1, wherein a first end of a cable is electrically connected to at least a first contact element of the sliding contact arrangement, and wherein the cable is passed through a section of the first unit.

11. The drill head according to claim 10, wherein the first contact element and the first contact arrangement is electrically connectable to a cable passed through the inner drill pipe.

12. The drill head according to one of the preceding claims, characterized in that the first unit comprises one of a roller bit arrangement coupleable with the inner drill pipe and a down-the-hole hammer coupleable with the inner drill pipe.

13. The drill head according to claim 1, wherein a drilling fluid exiting at the drill head-side end of the double-drill pipe assembly from the assembly is conducted to the front end opposite to the drill pipe-side end of the drill head and exits the drill head thereat.

14. A device for drilling a bore in the ground, comprising a drill head according to claim 1, a double drill pipe assembly, and a drive unit, the drive unit driving the inner drill pipe and the outer drill pipe of the double drill pipe assembly at different speeds of rotation and/or in different directions of rotation.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 shows a perspective side view of a drill head according to a first embodiment.

(2) FIG. 2 shows a sectional view of the drill head according to FIG. 1.

(3) FIG. 3 shows a perspective side view of a sliding contact arrangement according to a first embodiment.

(4) FIG. 4 shows a sectional view of the sliding contact arrangement according to FIG. 3.

(5) FIG. 5 shows a perspective sectional view of a detail of the drill head according to FIGS. 1 and 2 with the sliding contact arrangement according to FIGS. 3 and 4 inserted into the drill head.

(6) FIG. 6 shows a perspective sectional view of the rear end of the drill head according to FIGS. 1 and 2.

(7) FIG. 7 shows a sectional view of a detail of the drill head according to FIGS. 1 and 2.

(8) FIG. 8 shows a sectional view of a further detail of the drill head according to FIGS. 1 and 2.

(9) FIG. 9 shows a perspective side view of a drill head according to a second embodiment.

(10) FIG. 10 shows a further perspective side view of the drill head according to FIG. 9, and

(11) FIG. 11 shows a sectional view of a sliding contact arrangement according to a second embodiment.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

(12) FIG. 1 shows a perspective side view of a rock drill head 10 according to a first embodiment. At its front end, the rock drill head 10 has a roller bit arrangement 12, which is also referred to as tricone, and at its rear end 14 a first interface 16 for connecting the rock drill head 10 to the inner drill pipe of a double drill pipe assembly and a second interface 18 for connecting the rock drill head 10 to the outer drill pipe of the double drill pipe assembly. The first interface 16 and the second interface 18 each have a conical internal thread into which a respective conical external thread present at the end of the inner drill pipe and at the end of the outer drill pipe can be screwed. In other embodiments, the interfaces 16, 18 and the external threads of the inner drill pipe and of the outer drill pipe can have non-conical, i.e. cylindrical threads or other connecting elements.

(13) The roller bit arrangement 12 comprises three roller bits 12a to 12c which upon a rotation of the inner drill pipe, which is connected to the rock drill head 10, about an axis of rotation 20 rolls upon the earth present in front of the rock drill head 10 in feed direction P1 and, in doing so, removes earth particles, so-called cuttings, from the earth. The earth can in particular be rock material, the roller bits then removing rock particles upon a rotation about the axis of rotation 20. The rock drill head 10 can be used in a direction-controlled drilling device, in particular in a horizontal drilling system which is also referred to as horizontal direction drilling device. Here, a drive unit drives the inner drill pipe and the outer drill pipe of the double drill pipe assembly with different drive heads. The inner drill pipe as well as the outer drill pipe can each be assembled from several drill pipe sections, common drill pipe sections having a length in the range between 3 and 4.5 m. The drill pipe sections of the inner drill pipe are usually screwed to each other. The drill pipe sections of the outer drill pipe, too, are screwed to each other so that both the drill pipe sections of the inner drill pipe and the drill pipe sections of the outer drill pipe are connected to each other in a rotationally fixed manner at least in one direction of rotation. The inner drill pipe drives the roller bit arrangement 12 at a speed of rotation in the range of usually 30 to 300 rpm. Through the inside of the inner drill pipe a bentonite drilling fluid is pumped which exits at the front end from the rock drill head 10 in the area of the roller bit arrangement 12 and transports the earth particles excavated by the roller bit arrangement 12 through the bore channel backward out of the bore channel. At the same time, the bentonite drilling fluid stabilizes the bore channel. The rock drill head 10 has an outer casing 22 and an inner drill pipe adapter 24, at the drill pipe-side end of which the first interface 16 is provided. The inner drill pipe adapter 24 is connected to the roller bit arrangement 12 in a rotationally fixed manner via an inner tube not visible in FIG. 1 so that the inner drill pipe adaptor 24 and the inner tube transmit the rotary motion of the inner drill pipe to the roller bit arrangement 12. In other embodiments, the rock drill head 10 can also have a gearing stage with a gear increase or a gear reduction so that the speed of rotation of the inner drill pipe and the speed of rotation of the roller bit arrangement 12 can be different.

(14) The outer casing 22 has a cover which is formed as a flange plate 26 and covers a sonde chamber 42 provided in the outer casing 22 in a water-proof manner. The flange plate 26 has a window 28 made of a material that is permeable to the sonde signal so that a sonde signal can pass through the window 28. As a result, it is possible to locate the sonde signal generated by the sonde by means of a known locating device from the earth's surface. The outer casing 22 is bent by 2° at a bend 30 so that the angle of the center axis of the portion of the outer casing 22 before the bend 30 spans an angle of 178° with respect to the center axis of the portion of the outer casing 22 after the bend 30. In other embodiments, the bend 30 can also have an angle in the range between 1 and 10°, in particular 2° to 5°. As an alternative to the bend 30, the outer casing 22 may also have a corresponding curvature by means of which the roller bit arrangement 12 has the same relative position to the first and the second interface 16, 18 of the rock drill head 10.

(15) By means of the bend 30 or by means of a corresponding curvature of the outer casing 22 of the rock drill head 10 a controlled drilling is possible. Dependent on the angular position of the outer casing 22, the front part of the rock drill head 10 is inclined with respect to the rear part of the rock drill head 10 by 2° downward, by 2° to the right, by 2° to the left or by 2° upward or in a corresponding intermediate position between these positions so that the drill head 10 produces a bore with a correspondingly curved path without a rotation of the outer casing 22. To produce a straight bore, the outer casing 22 of the rock drill head 10 has to be rotated continuously with a rotation in the range of 30 to 60 rpm. For this, the outer casing 22 is connected at the rear end 14 via the second interface 18 to the outer drill pipe of the double drill pipe assembly. The second interface 18 preferably has an internal thread into which an external thread of the outer drill pipe is screwed. As a result, the outer drill pipe can rotate the outer casing 22 of the rock drill head 10 at least in one direction of rotation. If the bore produced by means of the rock drill head 10 shall have a curved path, then the rotation of the outer casing 22 is stopped dependent on the desired direction of the curve in an angular position required for this and only the inner drill pipe is driven for an advance of the rock drill head 10. In addition, the rock drill head 10 is pressed further into the earth via the drill pipe by means of a drive unit. If the rock drill head 10 produces a curvature, i.e. if the rock drill head 10 moves along a curve, then it is supported with a front support plate 32 and its rear support plate 34 at the bore channel. The hard metal pins 38 arranged at a rear conical section 36 of the outer casing 22 serve to pull out the rock drill head 10 backward from the bore channel in a rotating manner, if necessary.

(16) Next to the sonde chamber 42 closable by the flange plate 26, the rock drill head 10 has a slip ring chamber 52 closable in a water-proof manner by means of a flange plate 40, in which slip ring chamber a sliding contact arrangement can be arranged if necessary, as will still be explained in more detail further below.

(17) FIG. 2 shows a sectional view of the rock drill head 10 according to FIG. 1. In this illustration, the sonde chamber 42 covered by means of the flange plate 26 is well visible. In the sonde chamber 42, a sensor unit 44 is arranged. Between the front end of the sensor unit 44, as viewed in feed direction P1, and the outer casing 22, a first damping element 46 is provided and between the rear end of the sensor unit 44, as viewed in feed direction P1, and the outer casing 22 a second damping element 48 is provided in the sonde chamber 42. The damping elements 46, 48 protect the electronic sensor unit 44 against shocks and impacts, which in particular occur as a result of the drilling operation. The sensor unit 44 is inserted laterally into the sonde chamber 42 when the flange plate 26 is open. By way of the slot 28 provided in the flange plate 26, a position signal emitted by the sensor unit 44 can reach the outside, preferably the earth's surface above the rock drill head 10. The energy required for this as well as required data and/or signals can be transmitted via a cable 50 from the earth's surface through the double drill pipe assembly up to the rock drill head 10. The cable 50 runs in the inner drill pipe of the double drill pipe assembly up to the drill head 10. The sonde chamber 42 is, however, located in the outer casing 22 of the rock drill head 10. In the present embodiment, the drill head 10 has two circumferential slip rings 56, 58 formed on a base body 54 connected to an inner drill pipe adapter 24 in a rotationally fixed manner as well as in the outer casing 22 brush arrangements which are complementary to the slip rings 56, 58, a further cable for connecting the brush arrangement and the sensor unit 44 being provided. In other embodiments, the sliding contact arrangement 60 consisting of the slip rings 56, 58 and the complementary brush arrangements can also comprise only one slip ring and one complementary brush arrangement or more than two slip rings and two complementary brush arrangements, in particular four slip rings and four complementary brush arrangements. In the case of four slip rings and four complementary brush arrangements, two slip rings and two complementary brush arrangements can be used for transmitting the energy required for the voltage supply of the sensor unit 44, and two lines for the data and/or signal transmission between a control unit arranged at the earth's surface and the sensor unit 44. If the sensor unit 44 is, however, only used for emitting position signals which can be located from the earth's surface, the energy supply of the sonde can be accomplished via the cable 50 and the sliding contact arrangement 60. Thus, it is not necessary to also arrange batteries or accumulators in the rock drill head 10 so that in particular the sonde chamber 42 can be designed correspondingly smaller.

(18) Additionally or alternatively, the sensor unit 44 can determine the position of the rock drill head 10 and transmit the determined position as a signal or as data via the sliding contact arrangement 60 and the cable 50 to a control unit at the earth's surface. Additionally or alternatively, the sensor unit 44 can determine the inclination of the rock drill head 10 and/or the angular position of the outer casing 22 of the rock drill head 10 and transmit these via the sliding contact arrangement 60 and the cable 50 to the control unit at the earth's surface.

(19) As an alternative to the sensor unit 44, a battery-powered trackable sonde can be inserted into the sonde chamber 42 if in an intended drilling operation the drill head is trackable conventionally with a locating device from the earth's surface. In this case, when the inner drill pipe adapter 24 is disassembled, the base body with the slip rings 56, 58 can be removed from the slip ring chamber 52 when the flange plate 40 is open. Alternatively or additionally, also the brush arrangement is removed from the rock drill head 10. In this way, the rock drill head 10 can be used like a conventional rock drill head without sliding contact arrangement 60 and can be re-inserted into the rock drill head 10 in the case of drillings which require an energy, data and/or signal transmission to and/or from the sensor unit 44 via the cable 50. As a result, wear of the sliding contact arrangement 60 is prevented whenever it is not required for drilling. The cable 50, too, can completely be removed from the inner drill pipe adapter 24 so that the cable 50 is neither damaged nor is the assembly of the inner drill pipe with the inner drill pipe adapter 24 impeded. The cable feed-through for the cable 50 into the slip ring chamber 52 is sealed by means of a suitable cable gland. When removing the cable 50, the cable feed-through is sealed by a corresponding dummy plug or a corresponding closing plug so that the slip ring chamber 52 is also sealed without a cable 50 and in particular no drilling fluid can enter the slip ring chamber 52.

(20) Sensor units 44 which are connected to a control unit at the earth's surface via a cable 50 are also referred to as cable sondes. A cable sonde thus enables extreme drillings with great locating depths and under surfaces which do not allow that locating devices are carried along the earth's surface vertically above the drill head 10. For example, in the case of drillings under rivers or lakes, locating devices cannot readily be carried along at the earth's surface. Likewise, drillings in depths are possible in which a transmission from battery-powered sondes to locating devices at the earth's surface are not possible. Both by means of a higher transmission power due to a voltage supply via the cable 50 and by the active determination of the position of the rock drill head 10 by means of the sensor unit 44 and by transmitting position information via the cable 50 to the earth's surface drillings at great depths are possible. Here, the invention is based on the realization that it is more favorable to pass the cable 50 inside the inner drill pipe instead of between the inner drill pipe and the outer drill pipe since thereat it could easily be damaged due to different speeds of rotation and/or directions of rotation. Instead, the cable 50 is passed inside the inner drill pipe up into the drill head 10, wherein the energy, data and/or signals are transmitted by the cable 50 via a sliding contact arrangement 60 to the outer casing 22 of the rock drill head 10 in which the sensor unit 44 is arranged.

(21) In FIG. 3, the sliding contact arrangement 60 is illustrated in the removed state, wherein both the base body 54 and the brush arrangement 62 are illustrated. FIG. 4 shows a cross-section through the sliding contact arrangement 60. The brush arrangement 62 is connected via a lug 64 and a screw that can be passed through an opening of the lug 64 to the outer casing 22 of the rock drill head 10. Via the lug 64, the brush arrangement 62 is fixed to the sonde chamber 52 and thus to the outer casing 22 in a rotationally fixed manner. Further, the brush arrangement 62 is connected to the sensor unit 44 via a cable 66. The base body 54 with the slip rings 56, 58 is secured on the external hexagon of the inner drill pipe adapter 24 by means of several threaded pins 68. The sliding contact arrangement 60, as already explained, serves to electrically transmit energy, data and/or signals from the outer casing 22 to the inner drill pipe. In the same manner as the cable 50, the cable 66 is sealed in a water-proof manner by means of a cable gland in a sealing area 70 illustrated in FIG. 5. The fitting and the removal of the sliding contact arrangement 60 into and from the rock drill head 10 is accomplished by means of the removal of the flange plate 40 and the disconnection of the threaded pins 68. Further, the inner drill pipe adapter 24 is disconnected and pulled backward out of the drill head 10. Further, the cable glands provided for sealing are disconnected from the cables 50, 66. Subsequently, the sliding contact arrangement 60 with the cables 66, 50 can be removed from the slip ring chamber 52. The cable 50 is composed of several cable sections which preferably correspond to the length of the drill pipe sections of the double drill pipe assembly. The cable ends of the cable sections are electrically connected in a suitable manner and are both electrically isolated and sealed against the drilling fluid additionally transported through the inner drill pipe. After disconnection of the cable 66 from the sensor unit 44, the sliding contact arrangement 60 together with the cable sections 50, 66 can completely be removed from the slip ring chamber 52 and the drill head 10. As already explained, the drill head 10 can then be used with conventional battery-powered sonde arrangements.

(22) FIG. 5 is a sectional view of a detail of the rock drill head 10. The sealing of the cable 50 passed through the inner drill pipe adapter 24 against the slip ring chamber 52 is provided in the areas 72 and 74.

(23) FIG. 6 shows a detail of a rear end of the rock drill head 10, and the detailed view illustrated in FIG. 7 shows a plug connection between the inner drill pipe adapter 24 and an inner tube 76 of the drill head 10 that transmits the rotary movement of the inner drill pipe adapter 24 to the roller bit arrangement 12. The inner drill pipe adapter 24 is mounted in the outer casing 22 via two bearings 78, 80. Typically, these bearings are tapered roller bearings. Both bearings absorb radial forces, the bearing 80 additionally absorbs thrust forces in feed direction P1, the bearing 78 additionally absorbs tension forces opposite to the feed direction P1. Via a nut 82 which is accessible via the slip ring chamber 52 and is screwed onto an external thread of the inner drill pipe adapter 24, the inner drill pipe adapter 24 is kept in this position. For disconnecting the base body 54 of the sliding contact arrangement 60 from the inner drill pipe adapter 24, an open-end wrench has to be inserted into the slip ring chamber 52 after removal of the flange plate 40, by means of which the nut is kept in its position. Subsequently, the inner drill pipe adapter 24 is rotated so that the inner drill pipe adapter 24 is rotated out of the nut and is disconnected therefrom. Thereafter, the inner drill pipe adapter 24 can be pulled backward out of the drill head 10. Near its front end, the inner drill pipe adapter 24 has an external hexagon 84 and a circumferential groove 86 into which a non-illustrated seal, preferably an O-ring, is inserted. The external hexagon 84 has a large lateral play with respect to an internal hexagon socket 88 connected to the inner tube 76, which socket in turn has a relatively large play with respect to an external hexagon of the inner tube 76. This connection enables a transmission of the torque while at the same time providing alignment compensation.

(24) FIG. 7 shows a detail of the elements for alignment compensation illustrated in FIG. 6 at the interface between the inner drill pipe adapter 24 and the inner tube 76. As can be seen thereat, the front end of the inner drill pipe adapter 24 has a circumferential groove 86 into which a non-illustrated seal, preferably an O-ring, is inserted for sealing between the inner drill pipe adapter 24 and the inner tube 76. The drilling fluid is led from the inner drill pipe through the inner drill pipe adapter 24 into the inside of the inner tube 76 and through this tube to the roller bit arrangement 12.

(25) FIG. 8 shows a sectional view of a detail of the drill head 10 at the junction between the inner tube 76 and the so-called roller bit receptacle 94. This connection is established with alignment compensation. At the front end, the inner tube 76 has an external hexagon 92 which projects with a lateral play into a complementary internal hexagon section of the roller bit receptacle 94. At the front end before the internal hexagon, the inner tube 76 has a circumferential groove 90 into which for sealing between the inner tube 76 and the roller bit receptacle 94 a seal, preferably an O-ring, is inserted. Further, several bearings 96a to 96f arranged one after the other in feed direction P1 are arranged which, in the present embodiment, are designed as ball bearings. In other embodiments, also other suitable bearings can be provided. The bearings 96a to 96f guide and hold the roller bit receptacle 94.

(26) In FIG. 9 and FIG. 10, a perspective side view of a drill head 100 according to a second embodiment is shown. The drill head 100 differs from the rock drill head 10 according to FIGS. 1 to 8 only in that instead of the roller bit arrangement 12 a down-the-hole hammer 102 is provided. This down-the-hole hammer 102 is driven by means of compressed air which is led through the inner drill pipe and by means of which the hammer ram of the down-the-hole hammer 102 is driven with up to 2,500 strikes per minute. The hammer ram of the down-the-hole hammer 102 directly strikes the drilling tool 104, the hard metal pins of which excavate the earth, in particular rock material. The exhaust air of the down-the-hole hammer 102 blows the excavated earth particles backward through the bore channel. Here, the inner drill pipe may not be driven or, alternatively, be rotated in the same manner as indicated for the rock drill head 10. The controlled drilling by means of the drill head 100 is performed in the same manner as described in connection with the drill head 10 as due to the bend 30 the drill head 100 a bent bore is produced and only by way of a rotation of the outer casing 22 a straight bore is made possible.

(27) In FIG. 11, a sectional view of a sliding contact arrangement 110 according to a second embodiment is shown. At the base body 112 of the sliding contact arrangement 110 the slip rings are not provided at the circumference of the base body 112 but at a face-side section 114. In the present embodiment, two slip ring contacts 116, 118 are provided at the end face section 114, wherein in a stator 120 of the sliding contact arrangement 110 complementary brush arrangements for establishing an electrical contact between the slip ring contacts 116, 118 and the stator 120 are provided. The sliding contact arrangement 110 can be inserted into the drill heads 10, 100 as an alternative to the sliding contact arrangement 60.

(28) The sliding contact arrangements 60, 110 preferably have a base body 54, 112 with at least one slip ring 56, 68, 116, 118. The base body 54, 112 with the slip ring 56, 68, 116, 118 forms a structural unit together with at least one complementary brush arrangement 62, which structural unit can preferably jointly be removed from the drill head and inserted therein.

(29) As an alternative to the sliding contact arrangements 60, 110 arrangeable in the drill head 10, 100, the sliding contact arrangement can also be designed as an adapter which is arranged between a conventional drill head and the double drill pipe assembly.

(30) The foregoing description of embodiments of the present invention has been presented for the purpose of illustration and description. It is not intended to be exhaustive or to limit the invention to the form disclosed. Obvious modifications and variations are possible in light of the above disclosure. The embodiments described were chosen to best illustrate the principles of the invention and practical applications thereof to enable one of ordinary skill in the art to utilize the invention in various embodiments and with various modifications as suited to the particular use contemplated.