Abstract:
The invention relates to a device for drilling a bore in the ground, comprising a drive system with a connecting rod assembly that extends from the drive system into the ground. The end of said assembly pointing towards the face or base of the bore is connected to a tool head ( 40 ). The device also comprises several tools ( 41 ) that are located on the tool head ( 40 ) and work on the face or the base of the bore. The inventive device is characterised in that each tool ( 41 ) comprises an excavation disc ( 45 ) and elements that cause the excavation disc ( 45 ) to oscillate during operation.

Description:
BACKGROUND OF THE INVENTION 
   The invention relates to a device for drilling a bore in the ground. 
   A device of this type is disclosed by WO 97/34070. The percussive tools are in this case connected directly in a plurality to the tool head, so the percussive energy is transferred via the drive medium to the tools sunk in the bore and from said tools directly to the base of the bore, so that the connecting rod assembly remains largely unaffected thereby. The tool head is connected via the connecting rod assembly to a drive device, normally arranged outside the bore and having a rotary drive, so that the tools arranged on the tool head operate at points on the base of the bore which are always new. The devices mentioned are mostly used to operate in solid rock. 
   In practice, this type of drilling is of increasing importance since, firstly, the quality of the bores is better and the direction of the bores can be maintained virtually exactly; secondly, because of the sound-absorbing method of use in the bore without any substantial external effect, environmental criteria such as noise nuisance are satisfied considerably better. 
   In installations of this type, transporting the rock material separated and excavated away at the face or the base of the bore out of the bore can be carried out within the hollow connecting rod assembly in the manner of what is known as “reverse circulation”. For instance, the air lift method can be used for this purpose, in which air as a flushing medium is blown into the drilling assembly above the tool head, so that the air rising in the connecting rod assembly produces a pressure difference in the connecting rod assembly between bore and surface, which induces a flow velocity in the connecting rod assembly, with which the rock material is driven out through the connecting rod assembly. 
   In the case of the known device, percussive hammers are used as tools. Although, by using this device, satisfactory drilling progress is achieved, in particular in hard rock, it is disadvantageous that the drilling efficiency decreases, in particular in softer strata. 
   SUMMARY OF THE INVENTION 
   The invention is therefore based on the object of providing a device which ensures satisfactory drilling progress in an extremely wide range of rock formations. 
   This object is achieved by the invention in that each of the tools comprises an excavation disk and means which set the excavation disk oscillating in operation means that each tool simultaneously exerts on the face or the base of the bore a percussive action which loosens hard rock and also an excavating action which carries away loosened hard rock and softer soil formations. Different rock formations can thus be loosened and carried away efficiently with the device according to the invention. 
   Pins or disk rollers, in particular, can be used as removal means. 
   Particularly preferred is an embodiment of the device according to the invention in which at least one drive device is provided, by means of which the tool head can be set rotating about the bore longitudinal axis. The drive device can both be arranged outside the bore and the torques can be transmitted via the connecting rod assembly. However, it is likewise possible to mount the connecting rod assembly nonrotatably and to provide the drive device in or on the tool head. The rotational movement of the tool head ensures that the excavation disks operate at different points on the face or the base of the bore. 
   The drive device for the tool head can be equipped in such a way that the rotation takes place in a fixed direction of rotation, that is to say either in or counter to the clockwise direction. 
   However, it is likewise possible to configure the drive device in such a way that the rotation takes place in alternating directions of rotation, for example through rotational angles between 90° and 270°. This embodiment has the advantage that it is possible to dispense with complicated rotary leadthrough seals, such as would be necessary in order to supply fluid media to the tool head, or wiping contact arrangements such as would be necessary in order to introduce electric currents, for example in order to drive the tools. The seal and wiping contact arrangements can be replaced by simple flexible lines which are not susceptible to faults. 
   In a particularly preferred embodiment of the device according to the invention, means are provided which set the excavation disk of each tool rotating during the operation of the device. This measure intensifies the excavation action on the rock to be loosened, the drilling efficiency increases. The means are, for example, hydraulic, pneumatic or electric rotary drives. 
   Trials have shown that the drilling efficiency is particularly high if the rotational frequency of the excavation disk of each tool is lower than its oscillation frequency. The ratio between rotational frequency and oscillation frequency is preferably 1:30 to 1:60. 
   In a particularly preferred refinement of the device according to the invention, each tool comprises a rotationally driven main shaft which has a shaft journal whose axis forms an acute angle with the axis of the main shaft, and a head carrying the excavation disk, which is mounted such that it can rotate about the axis of the shaft journal and has a circumferential region which runs on an opposing circumferential region. As a result of this measure, the excavation disk is set in oscillation movement by the main shaft at a frequency which corresponds to the rotational frequency of the main shaft. As a result of the circumferential region of the head running on the opposing circumferential region, the rotation of the main shaft simultaneously sets the excavation disk into a rotation whose rotational frequency depends on the configurations of the circumferential region and of the opposing circumferential region. A fixed relation between oscillation and rotational frequency of the excavation disk can therefore be predefined by design. 
   However, in order to be able to adapt the device according to the invention optimally to different rock formations, it is particularly desirable to be able to vary the ratio of oscillation to rotation. In the particularly preferred embodiment of the device, this is made possible by the opposing circumferential region itself being capable of being set rotating. Depending on the direction of rotation of the opposing circumferential region, with a constant rotational speed of the main shaft, an increase or reduction in the resultant rotational speed of the excavation disk is thus effected. 
   The opposing circumferential region and the circumferential region running on it can be configured in any way which ensures the running action during operation. Because of the simplicity of production and the operational reliability, however, it is preferred for the circumferential region to have external toothing and for the opposing circumferential region to have internal toothing. 
   The opposing circumferential region is preferably formed by a hollow gear which is arranged concentrically with respect to the main shaft axis and which, according to the particularly preferred embodiment of the invention, can be set rotating. 
   It has been shown that the ratio of the oscillation frequency and the rotational frequency which can be achieved with a nonrotatable opposing circumferential region is not optimal for a large number of applications. Normally, a speed of the drill head with a lower ratio would be more advantageous for the drilling progress. A preferred embodiment of the device according to the invention therefore provides for the opposing circumferential region to be set rotating by means of an epicyclic gear mechanism which is in engagement with the main shaft. This embodiment has the advantage that it requires no further drive motors. 
   However, it is likewise possible to set the opposing circumferential region rotating by means of a separate drive, independently of the main shaft, that is to say not to couple the opposing circumferential region and main shaft. The separate drive is particularly preferably configured such that it can be controlled or regulated, which means that, during operation, adaptation of the ratio between the drill head rotational speed and oscillation frequency to the type of rock occurring in each case is possible. 

   
     BRIEF DESCRIPTION OF THE DRAWING 
     Exemplary embodiments of the device according to the invention are illustrated in the drawing, in which: 
       FIG. 1  shows, in perspective form, a first embodiment of a drive system of a device according to the invention; 
       FIG. 1   a  shows a rotary drive which, in the embodiment of the drive unit according to  FIG. 1 , can be used as alternative to the rotary drive illustrated herein; 
       FIG. 2  shows, in schematic form, the action of the air lift system in a device according to the invention; 
       FIG. 3  shows, schematically, a side view of a tool head having a plurality of tools; 
       FIG. 4  shows a view according to  FIG. 3  from below; 
       FIG. 5  shows the construction of one of the tools in longitudinal section; 
       FIG. 6  shows, in perspective form, a view corresponding to  FIG. 1  of a second embodiment of the drive system of a device according to the invention; 
       FIGS. 7 and 8  show two further embodiments of the drive system in a view corresponding to  FIG. 6 ; 
       FIG. 9  shows an oscillating drive, such as can be used in the embodiment according to  FIG. 8 ; 
       FIG. 10  shows the construction of a further embodiment of a tool in an illustration corresponding to  FIG. 5 ; and 
       FIG. 11  shows, in schematic form, a preferred arrangement of tools according to  FIG. 10  on a tool head. 
   

   DETAILED DESCRIPTION OF THE INVENTION 
     FIG. 1  shows a first embodiment of a part of a device according to the invention which is arranged outside a bore to be drilled in the ground. The drive system of the device, designated overall by  3 , is fixed to a supporting device  2  which is supported on a working platform designated overall by  1 . A rotary drive head  4 , shown schematically, acts on a connecting rod assembly  5  having segments that can be connected to one another, of which only the upper part is shown and which extends (indicated only dashed) through the working platform  1  into the bore to be drilled in the ground and as far as the tool head. The drive of the connecting rod assembly  5  having the rotary drive head  4  can be carried out in a conventional manner known from the prior art, for example via a hydraulic motor. 
   Alternatively, however, it is likewise possible, instead of the rotary drive head  4  arranged at the upper end of the connecting rod assembly  5 , to use a rotary drive  4 ′ illustrated in  FIG. 1   a , such as is known in design terms per se from piping devices. 
   This rotary drive  4 ′ comprises a stationary, outer part  4 ″, opposite which an annular inner part  4 ′″, whose internal diameter is matched to the external diameter of the connecting rod assembly  5  and can optionally be connected to the latter, at least in the drive direction, in an operative connection, that is to say by a force fit or form fit, can be driven in rotation. The drive can be carried out, for example, by a hydraulic motor. With its stationary part  4 ″, the rotary drive  4 ′ can be operatively connected to variable-length force generators  2 ′, such as spindles or piston/cylinder units, provided on the supporting device  2 . If the connecting rod assembly  5  and the inner part  4 ′″ of the rotary drive  4 ′ are configured in such a way that a force-transmitting connection between the connecting rod assembly  5  and the inner part  4 ′″ can also be achieved in the longitudinal direction of the former, then a forward drive force can also be introduced into the connecting rod assembly via the rotary drive  4 ′. However, it is likewise possible to mount the rotary drive  4 ′ on the supporting device so as to be fixed and to configure the inner part  4 ′″ and connecting rod assembly  5  in such a way that the connecting rod assembly  5  can be displaced in the inner part  4 ′″ in its longitudinal direction. In this case, the forward drive forces have to be introduced into the connecting rod assembly, for example, by acting on the first rotary connecting head  10 , yet to be described. 
   Arranged at the upper end of the connecting rod assembly  5  is a first rotary connecting head, designated by  10 , via which the material loosened at the base of the bore in the ground is carried away to the outside via an outlet pipe  21  and compressed air is introduced into the connecting rod assembly by means of a first feed line  13 . Arranged under the first rotary connecting head  10  is a second rotary connecting head, designated overall by  20 . The supporting device  2  can be swiveled about a horizontal axis A and is connected to swiveling drives  6 , so that it can be inclined and it is also possible for bores in the ground to be drilled in a manner deviating from the vertical. 
     FIG. 2  explains in schematic terms the method by which the drilled material loosened by tools  41  of a tool head  40  is conveyed outward from the base  16  of the bore  9  in the ground, partially filled with water, for example as far as a level  9 ′. The interior of the connecting rod assembly  5  forms a flushing pipe  8 , which is normally filled with water, into which air is blown in above the tool head  40  through an inlet valve  43 , having been compressed outside the drilling apparatus by a compressor, not shown, and is led downward along the connecting rod assembly  5  by means of a first feed  12  via a first feed line  13  on the first rotary connecting head  10 . The air blown in effects an upward flow within the flushing pipe  8  as a result of the difference in density between the liquid interspersed with air bubbles in the flushing pipe  8  and the external liquid in the bore  9  in the ground, with which upward flow the drilled material  7  is transported upward and flushed out of the device via the outlet pipe  11 . Via a second feed line  23  in the second connecting head  20  of the second feed  22 , shown in one piece with the first connecting head, the operating medium is supplied and, via the latter, is led downward along the connecting rod assembly  5  in order to drive the tools  41  of the tool head  40 . The operating medium used can be hydraulic fluid under pressure. However, it is likewise possible to configure the drive for the tools electrically. Instead of the second connecting head, a wiping contact arrangement can then be used in order to feed the electrical energy in. 
   In  FIGS. 3 and 4 , a tool head  40 , which is provided for a hydraulic drive, for example, is shown schematically. The tools  41  driven by the hydraulic medium are connected via supports  44  to a mounting plate  42 , which is fitted to the lower end of the connecting rod assembly  5 . The excavation disks  45  arranged on the tools  41  act downward on the base  10  of the bore  9  in the ground and fragment the rock there. The respective point of action moves onward in the circumferential direction as a result of the rotation of the tool head. By fitting the tools  41  at different radii, it is possible to sweep over the entire bore cross section. The number and arrangement of the tools  41  can be matched to the diameter of the bore  9  in the ground and the material to be removed. At their lower ends, the tools  41  are held and guided on a guide plate  46  shaped like a circular disk with a diameter corresponding to the diameter of the bore in the ground. 
     FIG. 5  shows a tool  41  in a detailed illustration. It comprises a head  46  which carries the excavation disk  45 . The excavation disk  45  is fixed to the head  46  by a plurality of cylindrical-head bolts  47 , of which only one is illustrated in the drawing. 
   The excavation disk  45  is provided with a central cutter  48 . The excavation disk  45  in the exemplary embodiment demonstrated has three arms  50  which extend radially outward and which, as can be seen in the case of the arm illustrated on the left in the drawing, are filled with a plurality of chisels  51 . 
   The head  46  is rotatably mounted by means of tapered roller bearings  52 ,  53  on a shaft journal  54  of a main shaft  55 . The shaft journal  54 , having a substantially cylindrical outer circumferential surface, is integrally molded on the main shaft  55  in such a way that its axis B forms an acute angle w of about 3° with the axis of rotation AA. 
   The main shaft  55  is in turn mounted by means of tapered roller bearings  56 ,  57  in a machine housing  58  such that it can rotate about the axis of rotation AA and is driven in rotation by a hydraulic motor  59  flange-mounted at the end. 
   The part of the head  46  facing away from the excavation disk  45  is formed as a gear wheel, called the oscillating gear  60  in the following text, arranged concentrically with the axis B of the shaft journal  54 , and therefore formed as a circumferential region  61  which, during rotation of the main shaft  55 , runs in internal toothing  63  acting as an opposing circumferential region  62 . 
   The internal toothing  63  is formed on a hollow gear  64  arranged concentrically with respect to the main shaft axis and mounted such that it can rotate with respect to the latter. 
   At the end opposite to the internal toothing  63 , the hollow gear has further internal toothing  65 , which is part of an epicyclic gear mechanism designated overall by  71 . The toothing of the parts of smaller diameter  67  of the planet gears  66  engages in the internal toothing  65 . The parts  68  of larger diameter of the planet gears  66  engage with their toothing in external toothing  69  provided on the main shaft  55  and also in internal toothing  70  provided in the machine housing  58 , so that, during the rotary drive of the main shaft  55 , the planet gears circulate around the axis of rotation AA in the same direction of rotation. Here, the hollow gear  64  is set rotating in the direction opposite to the excavation disk  45 , whose rotation is moved as a result of the oscillating gear  60  running on the internal toothing  63 . It goes without saying that, by selecting the ratios in the epicyclic gear mechanism  71 , the rotational speed of the hollow gear  64  relative to the main shaft  55  and thus, as a result, the ratio of oscillation frequency to rotational frequency of the excavation disk  45  can be predefined. 
     FIG. 6  shows a second embodiment of a drive device. Mutually functionally corresponding parts are provided with designations increased by 100. The basic structure largely corresponds to that of  FIG. 1 . To this extent, the description there also applies to the present embodiment. 
   The drive system of the device, designated overall by  103 , is fixed to a supporting device  102  which is supported on a working platform designated overall by  101 . A rotary drive head  104 , shown schematically, acts on a connecting rod assembly  105  which extends through the working platform  101  into the bore to be drilled in the ground and as far as the tool. The drive of the connecting rod assembly  105  by means of the rotary drive head  104  can be carried out in a conventional manner known from the prior art. 
   Arranged at the upper end of the connecting rod assembly  105  is a first connecting head, designated by  110 , via which material loosened at the base of the bore in the ground is carried away outward via the outlet pipe  121 , and a flushing fluid, normally air, is introduced into the connecting rod assembly  105  by means of a first feed line  113 . Arranged underneath the first connecting head  110  is a second connecting head, designated overall by  120 . The supporting device  102  can be inclined about a horizontal axis A by means of a swiveling drive  106 , so that it is also possible for bores in the ground to be drilled in a manner deviating from the vertical. 
   In the second embodiment of the drive device, the second connecting head  120  can rotate as a whole with the connecting rod assembly  105 , and only the first rotary connecting head  110  is mounted so as to be stationary. The rotary drive  104  is designed in such a way that it rotates the connecting rod assembly  105  having the second connecting head  120  for the drive medium of the hammers in the tool to and fro in an oscillatory manner through a predetermined angle about the axis of rotation of the assembly  105 . This swept angle is less than 360° and is chosen on the basis of the number and position of the tools  41  located on the same radius. In the case of only one tool  41  per radius, 360° are needed, in the case of two tools offset by 180° from each other per radius, a to and fro rotation of 180° suffices. However, it is likewise within the scope of the invention to rotate the tool head to and fro through an angle which is limited but greater than 360°. 
   As a result of the limited rotational angle, it is possible to operate a fixedly installed feed line for the drive medium that also participates in the rotational angle, without requiring a rotary seal or wiping contact arrangement. In the exemplary embodiment shown, the drive medium is introduced into the second feed  122  of the connecting rod assembly  105  by means of a flexible hose  115 . The hose  115  is mounted between the second feed line  123  and the second feed  122 . The length of the hose  115  is chosen such that the hose  115  can follow the rotation of the connecting rod assembly  105  without hindering the latter. 
   In a further embodiment, illustrated in  FIG. 7 , in which mutually functionally corresponding parts are provided with designations increased by 200 with respect to  FIG. 1 , the feed line  223  for the operating medium, the feed line  213  for the compressed air and the outlet pipe  221  are formed as flexible hoses. The two feed line pipes  213  and  223  are connected under the rotary drive  204 , at the points  213 ′,  223 ′, via flange arrangements not illustrated in detail, to the lines  212 ,  222  running on the connecting rod assembly  205 , through which the compressed air is fed to the inlet opening ( 43  in  FIG. 2 ) and the operating medium to the tool head ( 40  in  FIG. 2 ). The advantage of this embodiment is that the rotary drive head  204 , which, however, in this case effects only an oscillatory movement, merely has to comprise a rotary mounting for the connecting rod assembly  205  but it is possible to dispense entirely with rotary leadthroughs and rotary seals. 
   In this connection, it should be pointed out that it is not absolutely necessary to connect the flexible hoses  213 ,  223  to the lines  212 ,  222  at the points  213 ′ and  223 ′. Instead, it is likewise possible to dispense entirely with the rigid lines  212 ,  222  and to lead the hoses  213 ,  223  as far as the corresponding connecting points, located in the bore, on the connecting rod assembly and, respectively, on the tool head. Furthermore, it is obvious that, depending on the operation of the tools  41 , flexible electric cables could also be used instead of the flexible lines. 
   Instead of the rotary drive head  204  always acting on the upper end of the upper segment of the connecting rod assembly  205 , in this embodiment it is also possible to provide a rotary drive  4 ′ which acts on the connecting rod assembly  205  on the outside and whose mode of action and function also otherwise corresponds to that of the rotary drive  4 ′ but which effects only a to and fro movement of the connecting rod assembly. 
   A further embodiment of the device according to the invention is illustrated in  FIG. 8 . Mutually functionally corresponding elements are provided with designations increased by 300 relative to the embodiments in  FIG. 1 . In the case of this embodiment, an upper mounting in the context of the rotary drive  204  in  FIG. 7  or a rotary connecting head have been dispensed with completely. A drive unit  304 , which in terms of its function corresponds to that illustrated in  FIG. 9  and is yet to be described further below, is used for the oscillatory drive. 
   The hose lines  313 ,  323  are connected to the feeds  312 ,  322  and the hose line  321  is connected to the interior of the connecting rod assembly  305  with the aid of a flange head  360  which is arranged at the upper end of the upper segment of the connection rod and is constructed in such a way that connections provided on the latter for the hose lines  313 ,  323 ,  321  communicate with the lines  312 ,  322  and the interior of the connecting rod assembly. 
   The drive unit  304  is mounted on the supporting unit  302  via adjustable-length force generators  302 ′, such that the forward drive force can also be introduced into the connecting rod assembly via the drive unit  304  by lowering the drive unit  304 . Once the drive unit  304  has reached its lower position, further forward drive can be effected by “re-gripping”, by being released and fixed again after it has been displaced into a higher position with the aid of the force generator, and the procedure begins again. Since, in this device, no supporting unit whose length corresponds at least to that of one segment of the connecting rod assembly  5  is necessary, this embodiment is distinguished by a particularly low overall height. 
   The rotary drive  304 ′ illustrated in  FIG. 9 , which is known per se from piping machines and therefore is not to be described in detail, comprises a part  304 ′″ which can be set into an oscillatory movement with the aid of two piston/cylinder units and which is configured such that it can be folded up in many parts over its circumference. In order to connect it to the connecting rod assembly  305 , the part  304 ′″ pushed onto the latter is closed, so that it is operatively connected to the circumferential surface of the connecting rod assembly  205 . 
   A further embodiment of one of the tools  41  is illustrated in  FIG. 10 . In this tool, the carrier device for the removal means, implemented as a double arm  72 , executes only an oscillatory movement but no rotational movement. The mechanical construction of this tool is therefore simplified substantially as compared with that according to  FIG. 5 , since it is possible to dispense with an opposing circumferential surface on which the circumferential surface runs in order to produce the rotation, and therefore with the entire gear mechanism. 
   In addition, it is possible to dispense with individual drives for producing the oscillatory movement in each tool and, instead, to provide a central drive which is coupled to the tools. The central drive can contain a gear mechanism having drive shafts for each tool, in order in this way also to be able to vary oscillation frequencies. 
   The tools according to  FIG. 10  are arranged in the tool head in such a way that their double arms  72  extend at right angles to the tangents to the circles or circular sections which they sweep over on account of the rotation of the tool head. In addition, as illustrated schematically in  FIG. 11 , they are arranged to be offset laterally, so that individual cutting tools  451  operate in different tracks. 
   In this way, as compared with arrangements in which the excavation disks of the tools rotate and/or a plurality of cutting tools operate in one track, a coarser drilled material is obtained. The energy balance is more beneficial on account of the coarser drilled material, since the proportion of energy required for further comminution is dispensed with. 
   In the above text, only exemplary embodiment of devices according to the invention which are suitable for driving forward bores running substantially vertically have been shown. It goes without saying that the invention is not restricted to such bores but is also suitable for driving forward tunnel bores which run substantially in the horizontal direction.