HK1249770B - Rotary drilling tool and method for creating a hole in the soil - Google Patents

Description

The invention relates to a drilling tool for creating a borehole in the ground, comprising a body, a cutting device arranged on a lower side of the body for removing soil material, a feeding device for supplying flushing air into the area of the cutting device, and a conveying pipe for conveying the removed soil material and drilling suspension, which can be conveyed into the receiving area by means of the flushing air, according to the preamble of claim 1.

The invention also relates to a method for creating a borehole using a rotary drilling tool, in which cutting material is removed from the bottom of the base body of the rotary drilling tool by means of a cutting device, flushing air is supplied via a feeding device into the borehole filled with drilling suspension into the area of the cutting device, and the cut material is conveyed away via a conveying pipe by means of the flushing air, according to the preamble of claim 11.

A genus-specific rotary drilling tool is known from AU 6026173 A or EP 2 592 214 A1. The excavated ground material is transported out of the borehole via a discharge line using flushing air. At great drilling depths, there is a high demand for compressed air as flushing air. AU 6026173 A has a base body of the rotary drilling tool with a cutting device arranged on a bottom side of the base body for removing the ground material, and with a receiving area arranged in the upper region of the base body. In addition, this document provides an air flushing system which transports the removed ground material out of a borehole without sedimentation through an air conduit.

A core drilling tool with internal and external helical threads for generating a flushing flow is disclosed in DE 20 02015 102 848 U1.

In such a rotary drilling tool, it is generally advantageous that the flushing air can be used in two ways. Firstly, the flushing air serves to clean the cutting device, especially the roller bits when removing hard rock. For the operation of roller bits, it is essential that they can directly act on the exposed ground. At the same time, the flushing air acts as a conveying medium to transport the removed soil material upwards to the receiving chamber of the rotary drilling tool.

In known rotary drilling tools and methods, the flushing air continues to flow upward through the drilling fluid in the borehole, even as the soil gradually settles into the receiving chamber of the rotary drilling tool. The upward-flowing air can dislodge soil material from the borehole wall and thus destabilize it.

The invention is based on the task of providing a rotary drilling tool and a method for creating a borehole in the ground, which allow for efficient drilling when using flushing air.

After the invention, the task is solved by means of a drilling tool having the features of claim 1 and by means of a method having the features of claim 11. Preferred embodiments of the invention are specified in the respective dependent claims.

The inventive drilling and boring tool is designed such that the removed ground material is conveyed to a receiving area for sedimentation and collection on an intermediate floor, which is arranged in an upper section of the main body, that above the receiving area a collecting hood is provided, which closes an air collection space located above the receiving area, and that a drain valve is arranged on the collecting hood, which is designed to selectively discharge air from the air collection space by opening the drain valve.

The excavated soil material is transported from the bottom of the borehole by the introduced flushing air and can settle in a receiving chamber located in an upper part of the rotary drilling tool. When a certain filling level is reached, the rotary drilling tool is pulled out of the borehole and emptied at the ground surface. Subsequently, the drilling process can be continued.

The invention is based on the recognition that flushing air flowing upward can also carry soil material from the borehole wall upwards. As a result, the borehole wall can become unstable. In particular, when using a bentonite solution, a bentonite film forms on the borehole wall. This bentonite film has a stabilizing effect on the borehole wall. Due to upward-flowing flushing air, this stabilizing bentonite film can be damaged, thereby impairing the overall stability of the borehole.

The inventive design of the drilling tool comprehensively solves this problem. The upward flowing flushing air is captured above the receiving area by a collecting hood with an air collection chamber. Thus, the flushing air cannot continue to flow upward along the borehole wall.

At the hood, according to another aspect of the invention, a drain valve is provided, which allows air to be selectively discharged from the air collection chamber at certain times or under certain conditions.

Another advantage of the invention can be seen in that the air collected and removed in this way can generally be reused and directed back into the borehole as purge air. This purge air circulation is particularly environmentally friendly. A ring seal, in particular an inflatable ring seal, can be provided on the outer periphery of the collection hood to seal the gap between the borehole wall.

A preferred embodiment of the invention is that the relief valve is connected to an exhaust duct, through which air from the borehole can be discharged to the ground surface. The exhaust duct can be a hose or a pipe. This ensures that the captured air is reliably vented upwards without contacting the borehole wall.

In principle, the relief valve can be actuated by an operator, for example, in a drilling device. According to an improvement of the invention, it is advantageous if a control device is provided for controlled actuation of the relief valve. The control device may include sensors, such as level or pressure sensors, to determine an appropriate time or condition for releasing air. Preferably, the control device includes a sensor which actuates the control device to open the relief valve upon reaching a predetermined level in the collecting hood. When a predetermined condition is reached, the release of air can then take place automatically via the control device.

In this context, it is particularly advantageous according to one embodiment that the control device includes a float which floats at the interface between a drilling suspension and a flushing air under the collection hood. When a predetermined filling level is reached in the collection hood, the float actuates the control device to open the drain valve. With increasing operation, more and more air accumulates under the collection hood. As a result, the float, which floats at the interface between the drilling suspension and the air collection space, gradually sinks. When the float reaches a lower threshold level, the control device is actuated, opening the drain valve. The drain valve can remain open until the float again reaches an upper limit or an upper filling level. Then, the drain valve can be closed again by means of the control device.

The inventive rotary drilling tool is further developed in that a supply line for flushing air is provided, which leads from outside the borehole to the bottom side of the base body with the material removal device. In particular, flushing air can be continuously supplied from outside the borehole into the borehole toward the material removal device by means of a compressor. The supply line can have several outlet openings on the annular material removal device, in order to convey soil material from the bottom of the borehole as comprehensively as possible.

In principle, the ablation device can be designed in any manner. Particularly preferred, according to an embodiment of the invention, is that the ablation device comprises at least one rotatably mounted roller chisel and/or at least one fixed circular shaft chisel and/or at least one fixed ablation tooth.

A preferred further development of the invention is additionally characterized in that several rotatably mounted roller bits and/or fixed round shank bits and/or fixed cutting teeth are attached to the underside of the base body. By combining different cutting elements, a particularly good drilling progress can be achieved even under varying soil conditions.

Active cutting tools can also be provided, preferably axial movable hammers for processing the soil material. By supplying energy, such as compressed air or hydraulic fluid, these tools apply an axial striking movement to the adjacent, hard soil material.

Another suitable embodiment of the invention is that a connecting device for connecting the rotating drilling tool to a drilling drive means is arranged above the collecting hood. The connecting device can be specifically designed as a Kelly box, with which a drilling pipe, in particular a Kelly bar for transmitting a torque and a feed force, can be detachably and positively secured. The connecting device can be arranged in the center on the top side of the collecting hood. Thus, the rotating drilling tool can be used with conventional drilling equipment. A central rod may be provided, at the upper end of which the connecting device for torque transmission is attached. Preferably, the collecting hood is axially adjustable mounted on the central rod.

According to an improvement of the invention, it is advantageous that the rotary drilling tool is a core drill, which is designed to produce a core and to accommodate the core inside the tubular base body. The soil material is conveniently machined in a ring shape by the removal device, which has a ring-shaped configuration with cutting tools or removal elements. In a particularly efficient manner, a cylindrical core is thereby produced in the borehole by the ring-shaped removal of solid soil material.

It is preferable for a core sample to be securely held inside the main body by means of a core catch device and subsequently separated from the bottom of the borehole by applying force. The core sample can be conveyed to a ground surface either via a separate tool or together with the rotary drilling tool.

The invention also comprises a drilling device for creating a borehole in the ground, having a mast and a drilling drive for rotatably driving a rotary drilling tool, wherein the rotary drilling tool is designed as described above. By connecting the inventive rotary drilling tool with a drilling drive, which is mounted on a mast of a drilling device and rotates the drilling tool, boreholes can be created particularly efficiently in the subsoil and all soil materials present therein, and basically at all technically achievable depths.

Regarding the process, the above-mentioned object is solved according to the invention by conveying the removed soil material to a receiving area arranged in an upper section of the base body, providing a collecting hood above the receiving area, which closes the receiving area from above, forming an air collection space in which air accumulates, and arranging a drain valve on the collecting hood, with which air is discharged from the collection space.

With the inventive method, the advantages described previously can be achieved. Preferably, the method is carried out with the previously described rotary drilling tool, which has a collecting hood with an air collection chamber above a receiving space for the removed soil material. The collecting hood is preferably conical or dome-shaped, with the outlet valve for discharging the air arranged at an upper tip.

A preferred embodiment of the inventive method consists in that the drain valve is opened and closed by a control device. By means of automatic control, it is ensured that air is reliably discharged from the rotary drilling tool and that predefined threshold levels of the fill level within the rotary drilling tool are not exceeded or undershot.

The invention will be further explained below with reference to a preferred embodiment, which is schematically illustrated in the accompanying drawings. The drawings show: Fig. 1, a perspective view of a drilling tool according to the invention; Fig. 2, a cross-sectional view of the drilling tool of Fig. 1; and Fig. 3, a side view of the drilling tool of Figs. 1 and 2 with different positions of the collecting hood.

An inventive drilling tool 10 for creating a borehole in the ground will be explained below with reference to Figures 1 and 2. The drilling tool 10 comprises a base body 12 having a cutting device 20 on the bottom side of the base body 12. The cylindrical base body 12 is tubular and provided with a central drill core receiving portion 14. The cutting device 20 is annularly shaped and formed with several disc-shaped hammers 22. The hammers 22 are designed as so-called air hammers, which are moved axially back and forth by means of compressed air supply, thereby exerting impact pulses on the adjacent ground material to remove hard ground material.

The rotary drilling tool 10 has a central drill pipe 40 on the upper side of the main body 12, which is provided with an upper connecting device 42, designed as a so-called Kelly box. This is used to connect additional drill pipe elements in order to transmit a torque from a not-shown drilling device to the rotary drilling tool 10.

Through a feeding device 30, compressed air is supplied from the drilling machine to the base body 12. Through an upper feed line 32, compressed air is fed into an internal conduit channel 44 in the drill string 40. Through a intermediate conduit 34, the internal conduit channel 44 in the drill string 40 is connected to a cross channel 35 in the base body 12. From the cross channel 35, the compressed air can be further directed through a central tube 36 on the base body 12 to a horizontally extending distribution line 38 and subsequently to a vertically extending distribution line 39, which leads to the drive units of the hammers 22.

The compressed air consumed during activation of the hammers 22 is directed to convey the processed soil material into the borehole filled with suspension. The pressure fluid exiting at the lower end areas of the hammers 22 guides the excavated soil material to discharge openings 24 located on the underside of the main body 12. From the discharge openings 24, the excavated soil material can flow vertically upward through a discharge conduit 25 up to the upper end of the cylindrical main body 12, carried by the outgoing flushing air and the sucked-in drilling suspension. To support the flow and create a suction effect, compressed air can flow directly from the vertical distribution line 39 into the vertical discharge conduit 26 via one or more connecting channels 26.

At the upper end of the discharge ducts 25, bends 28 are provided with downward-facing outlet openings, so that the discharged soil material is directed downward into a cylindrical receiving area 18 on the main body 12. In this receiving area 18, the solid components of the discharged suspension can settle downward onto a intermediate plate 16 of the rotating drill tool 10. In the reverse direction, air exiting from the bends 28 can flow upward along the drilling axis.

According to an insight of the invention, the free upward flowing air can cause instability of the wall of the drilled hole. To counter this, in the rotary drilling tool 10 according to the invention, a collecting hood 50 with a sliding sleeve 51 is vertically movable and rotatably mounted along a cylindrical guiding section 41 of the drill pipe 40. The collecting hood 50 has a circular inlet area 53, whose outer diameter essentially corresponds to the diameter of the drilled hole. The collecting hood 50 encloses an air collection space 52, into which upward flowing air is taken in. An upper portion of the collecting hood 50 is provided with a narrowing 54, which leads into an exhaust duct 62 with an exhaust valve 60. The collecting hood 50 is rotatably mounted relative to the main body 12. Alternatively, it can also be fixedly connected to the main body 12.

The relief valve 60 is initially closed until a sufficient amount of air has accumulated in the air collecting chamber 52 of the collection hood 50. By means of an unshown control, the relief valve 60 is opened at certain times or when a specific air pressure or air volume is reached in the collection hood 50, allowing air to be controlled through the exhaust duct 62 from the borehole upwards.

In order to reliably prevent air leakage around the collection hood 50, a preferably inflatable ring seal 58 is provided at an outer periphery of a cylindrical section of the collection hood 50. The inflatable ring seal 58 is supplied with compressed air via a supply line 57, which in the illustrated embodiment is designed as simple bores leading to the air collecting chamber 52. When the pressure increases in the air collecting chamber 52, the ring seal 58 expands accordingly tightly. Alternatively or additionally, a compressed air supply line from outside can be provided, so that the inflatable ring seal 58 can be actuated at any desired time by means of a control system.

With the ring seal 58, the entire lower area of the bore below the catch hood 50 can generally serve as an air collection chamber 52. To increase this air collection chamber 52, the catch hood 50 can be adjusted vertically along the guide section 41 of the drill pipe 40, as clearly shown in Fig. 3. The adjustment can be performed by a non-illustrated adjusting device, for example using an adjusting cylinder, or automatically during operation by the rising and accumulated air in the catch hood 50.

Claims (13)

1. Rotary drilling tool for producing a bore in the ground with

   - a base body (12),

   - a removal means (20) arranged on an underside of the base body (12) for removing ground material,

   - a supply means (30) for supplying flushing air into the region of the removal means (20) and

   - a discharge line (25) for discharging removed ground material and drilling suspension, which can be conveyed away by means of the flushing air,

   wherein

   - in an upper section of the base body (12) a receiving region (18) for settling and receiving the removed ground material from the discharge line (25) onto an intermediate floor (16) is provided,

   - above the receiving region (18) a collecting hood (50) is arranged which closes off an air accumulation space (52) above the receiving region (18) in the upward direction, and

   - on the collecting hood (50) a drain valve (60) is arranged which is designed for the targeted discharge of air from the air accumulation space (52) through opening the drain valve (60).
2. Rotary drilling tool according to claim 1, characterized in that the drain valve (60) is connected to an exhaust air line (62), with which air can be discharged from the bore to the ground surface.
3. Rotary drilling tool according to claim 1 or 2, characterized in that a control means for the controlled actuation of the drain valve (60) is provided.
4. Rotary drilling tool according to claim 3, characterized in that the control means has a sensor which, on reaching a predetermined filling level in the collecting hood (50), actuates the control means to open the drain valve (60).
5. Rotary drilling tool according to any one of claims 1 to 4, characterized in that a supply line (32) for flushing air is provided which leads from outside the borehole to the underside of the base body (12) with the removal means (20).
6. Rotary drilling tool according to any one of claims 1 to 5, characterized in that the removal means (20) has at least one rotatably supported roller bit and/or at least one stationary round shank bit and/or at least one stationary removal tooth.
7. Rotary drilling tool according to any one of claims 1 to 6, characterized in that the removal means (20) has axially movable hammers (22).
8. Rotary drilling tool according to any one of claims 1 to 7, characterized in that a connecting means (42) for connecting the rotary drilling tool (10) to a drill drive instrument is arranged above the collecting hood (50).
9. Rotary drilling tool according to any one of claims 1 to 8, characterized in that the rotary drilling tool (10) is a core drill which is designed for producing a drill core and for receiving the drill core in the interior of the tubular base body (12).
10. Drilling apparatus for producing a bore in the ground with a mast and a drill drive for driving a rotary drilling tool (10) in a rotatable manner, characterized in that a rotary drilling tool (10) according to any one of claims 1 to 9 is provided.
11. Method for producing a bore in the ground with a rotary drilling tool (10), in particular according to any one of claims 1 to 9, in which

    - ground material is removed with a removal means (20) on an underside of a base body (12) of the rotary drilling tool (10),

    - by means of a supply means (30) flushing air is supplied to the bore filled with drilling suspension into the region of the removal means (20) and

    - by means of the flushing air removed ground material is conveyed away via a discharge line (25),

    wherein

    - the removed ground material is conveyed to a receiving region (18) which is arranged in an upper section of the base body (12) whereat the removed ground material settles on an intermediate floor (16) of the rotary drilling tool (10),

    - above the receiving region (18) a collecting hood (50) is provided which closes off the receiving region (18) in the upward direction by forming an air accumulation space (52), in which air accumulates, and

    - on the collecting hood (50) a drain valve (60) is arranged, with which air is discharged from the air accumulation space (52) through opening the drain valve (60).
12. Method according to claim 11, characterized in that the drain valve (60) is opened and closed by being controlled by a control means.
13. Method according to claim 11 or 12, characterized in that the rotary drilling tool (10) is drawn out of the borehole on reaching a determined filling and is emptied on the ground surface.