BOX DRILL AND METHOD FOR CREATING A BOIL

Description

[0001] The invention relates to a box drill for creating a borehole in the ground, comprising a drum-shaped housing which has an inner receiving chamber for receiving excavated soil material, at least one receiving opening on a bottom side and a substantially closed lid on the top side of the housing, and a removal device which is arranged in the area of ​​the bottom side of the housing and is designed for removing soil material, according to the preamble of claim 1.

[0002] The invention further relates to a method for creating a borehole in the ground with such a box drill according to the preamble of claim 10.

[0003] Box drills have long been used in the construction of boreholes in specialist foundation engineering projects. The diameters of the boreholes created are typically up to 1 meter or more. When a box drill is inserted into the ground, the excavated soil material is collected in the drum-shaped casing. Once the casing is sufficiently full, the box drill is withdrawn from the borehole and moved to an emptying position. At the emptying position, one end of the box drill can be opened, allowing the excavated soil material to fall out of the casing due to gravity.

[0004] In certain cases, however, the collected soil material may not empty easily from the drum-shaped housing. This can occur, for example, if the excavated soil contains a significant proportion of cohesive soils, such as clay or loam soils. Adhesion of the material within the box auger can also be increased by a relatively high fill level, in which case the soil material is compressed into the housing's receiving chamber.

[0005] To empty the box drill in such cases, it is known that the drilling rig performs a vibrating motion around the drill axis. This is noisy and does not always result in the desired emptying.

[0006] It is also known that in certain cases, operators direct a high-pressure water jet from below into the drill bucket to loosen adhering soil material. However, such soil removal is time-consuming and labor-intensive. Furthermore, strict safety precautions must be observed when operators perform such work on or below an open drill bit.

[0007] WO 2018 / 103919 A1 discloses a box drill in which flushing air lines supply flushing air to the drilling tools during drilling, thereby optimizing the contact area of ​​the roller bits. By injecting the flushing air at the bottom of the borehole, the formation of a bentonite film on the borehole wall can be effectively prevented.

[0008] US Patent 2014 / 0262522 A1 discloses a drilling rig with a box drill in which an axially displaceable push plate is arranged within the drum-shaped housing. This push plate allows the excavated soil material to be mechanically pushed downwards. However, such a box drill is mechanically complex, as it requires an axial actuator, in particular one or more hydraulic cylinders, to displace the push plate. Furthermore, corresponding hydraulic lines for the hydraulic cylinders must also be provided for power supply. Supplying hydraulic fluid from the drilling rig to a rotating drill bit necessarily requires a rotary union, which is expensive and maintenance-intensive.

[0009] Furthermore, a feed plate within the borehole chamber of the box drill, and especially the arrangement of hydraulic cylinders within the chamber, reduces the possible intake volume for soil material. This means that a greater number of drilling steps with the box drill are required to create a borehole. This reduces the efficiency of operation.

[0010] The invention is based on the Task The basis is to specify a box drill and a method with which, despite a simple design of the box drill, a borehole can nevertheless be efficiently produced in the ground even in cohesive soil material.

[0011] The problem is solved, firstly, by a box drill with the features of claim 1 and, secondly, by a method with the features of claim 11. Preferred embodiments of the invention are specified in the respective dependent claims.

[0012] The box drill according to the invention is characterized in that a pressure source is arranged at an upper area of ​​the housing, which is in line connection with the receiving chamber of the housing via a valve device, and that the valve device can be controlled via a control such that the valve device is open to empty the receiving chamber of soil material taken up during drilling, whereby a pressure medium flows into the receiving chamber.

[0013] A basic idea of ​​the invention is to facilitate the emptying of the receiving chamber of the box drill by introducing a pressurized medium, i.e., a gas or liquid. Particularly in highly cohesive soils, a plug of material can form in the box drill, which can be relatively easily dislodged by a pulse of compressed air from above.

[0014] To empty the box drill, the valve device can be opened before, during or after opening the box drill, allowing the pressure medium to flow into the upper area of ​​the receiving chamber in the housing, thereby assisting and / or causing the expulsion of the collected soil material downwards from the receiving chamber.

[0015] The box drill according to the invention significantly simplifies emptying, thus avoiding or at least reducing otherwise necessary, noisy vibration movements. The same applies to costly support measures by operating personnel, such as the use of a water jet.

[0016] The box drill according to the invention thus allows for a more efficient, quieter and safer creation of a borehole using a box drill.

[0017] In principle, the pressure medium can be introduced or generated in any suitable manner, for example by a compressor as part of a pressure source on the box auger or the associated drilling rig. A pressure reservoir, such as a filled gas cartridge, for example with CO₂, can also be provided, which is preferably easily replaceable. According to an advantageous embodiment of the invention, it is preferred that the valve assembly is controllable such that, during drilling, compressed air formed in the receiving chamber is drawn into a pressure vessel as a pressure source. When the box auger is withdrawn from the ground, the valve assembly is closed to retain compressed air in the pressure vessel, and the valve assembly is open to empty the receiving chamber of soil material taken up during drilling, allowing compressed air to flow back into the receiving chamber.

[0018] Consequently, the pressure medium is generated efficiently and energy-savingly during the drilling process by displacing the air present in the drill bit at the beginning of a drilling step upwards through the soil material and drilling fluid entering the drill bit from below. This compressed air is then compressed by hydrostatic pressure in the upper section of the drill bit. This compressed air can be collected in a pressure vessel located at the top of the drill bit. Before or during the withdrawal of the drill bit from the borehole, a pipe connection between the pressure vessel and the collection chamber can be closed, thus ensuring that the compressed air is retained even as the drill bit is pulled upwards.

[0019] A preferred embodiment of the invention further comprises a hinged bottom panel mounted on the underside of the housing, which is adjustable between a closed position for closing the housing downwards and an open position for emptying the receiving chamber. Hinging the bottom panel into the open position opens the lower part of the housing, thus enabling thorough emptying of the box drill.

[0020] It is particularly preferred that the hinged base has at least one receiving opening and that a rotary plate is rotatably mounted on the hinged base for opening and closing this receiving opening. Using the rotary plate, which is pushed into the open position in the direction of drilling rotation during operation, the receiving opening can be easily closed by briefly reversing the direction of rotation of the box drill. In this closed position, the box drill can be withdrawn from the borehole without the excavated soil material falling back into the borehole from the receiving chamber. This allows for efficient process execution.

[0021] To empty, the hinged bottom, together with the rotating plate, is then swung open around a swivel joint at the emptying position.

[0022] In principle, the removal device can be provided at any suitable position on the box drill. It is particularly preferred that the removal device is arranged on the hinged base and / or the rotating plate. In particular, the removal device is located in the area of ​​the at least one receiving opening, so that the removed soil material can pass directly through the receiving opening into the drum-shaped housing.

[0023] Another preferred embodiment of the box drill according to the invention consists in the provision of an additional closable through-opening in the housing's ceiling, through which a fluid can escape from the housing's receiving chamber to the outside. Particularly when the pressure vessel is lowered into an existing borehole during further drilling, air can initially be compressed by hydrostatic pressure in the upwardly closed receiving chamber and collected in the pressure vessel. After the valve assembly is subsequently closed, the through-opening in the housing's ceiling can be opened, allowing the drilling fluid collected in the drum-shaped housing, along with any remaining residual air, to flow upwards from the receiving chamber when drilling in a borehole with a supporting suspension, especially a drilling fluid.This creates sufficient space to accommodate the excavated soil material. A fluid can be a liquid, especially drilling fluid, and / or a gas.

[0024] It is particularly advantageous that the through-hole can be closed by means of a control valve, which is operated by a control unit. The control unit can regulate the opening and closing of the control valve at the through-hole and the valve assembly in relation to each other. After the valve assembly closes, the open control valve at the through-hole can be closed again at a point in time when a defined residual amount of drilling fluid remains above the excavated soil material in the upper area of ​​the drum-shaped housing's receiving chamber.

[0025] When emptying the drum-shaped box drill, the liquid layer can act as a kind of mechanical plunger when compressed air is introduced into the receiving chamber. This ensures that the pressure generated by the incoming compressed air is exerted over the largest possible area on the soil plug within the drum-shaped housing. This allows even a relatively small amount of compressed air to cause the soil material to be emptied abruptly. The opening can then preferably be reopened immediately, thus preventing the formation of a vacuum in the upper part of the receiving chamber during emptying. This pressure equalization further facilitates the emptying process.

[0026] In principle, the pressure medium can be introduced directly into the receiving chamber and expel the soil material through direct contact or via a layer of drilling fluid. A preferred feature of this further development of the invention is that an expansion element is arranged in an upper region of the receiving chamber, which can be moved further into the receiving chamber by the pressure medium for emptying. The expansion element can preferably be a flexible membrane or an inflatable film. Alternatively, a movable plunger can be provided, which can be moved by the pressure medium.

[0027] The invention further comprises a drilling rig with a carrier device having a rotary drive by which a box drill can be driven to create a borehole in the ground, wherein the box drill according to the invention described above is used. The carrier device can, in particular, be a conventional carrier device or drilling rig with a chassis and a superstructure rotatably mounted thereon. The chassis can, in particular, have a running gear, especially a tracked running gear.

[0028] A further development of the invention makes it particularly advantageous that a control unit for controlling the box drill is arranged on the support device. The control unit can control the valve assembly and / or the actuating valve at the through-hole. The control unit is preferably designed as an electronic control unit, which is connected to the actuating devices either via a cable or wirelessly.

[0029] To control the valve device or the control valve, a corresponding program control can be stored, which determines the respective time to open or close depending on the drilling process, in particular on the position of the box drill when lowering or pulling.

[0030] The inventive method provides for the use of a box drill according to the claims described above, wherein a pressure medium is introduced into the receiving chamber from the pressure source to empty the box drill of the soil material. The advantages described above can be achieved with this method. In particular, the method can also be carried out with the drilling rig described above.

[0031] A preferred method variant of the invention consists in the following: the box drill is inserted into the ground rotatingly, removing soil material; the removed soil material is received in the receiving chamber of the box drill; during drilling, a pressure vessel is filled with compressed air from the receiving chamber as a pressure medium, serving as a pressure source; when the box drill is withdrawn, the pressure vessel containing the compressed air is closed; and at an emptying position, the box drill is emptied of the drilled material, whereby the pressure vessel is opened and compressed air is introduced back into the receiving chamber to assist in emptying the removed soil material.

[0032] As previously described, this allows compressed air to be generated efficiently when lowering the box drill into the ground and when lowering it into an existing borehole.

[0033] As the drilling depth increases, a correspondingly higher pressure of compressed air can be generated in the pressure vessel. Particularly when drilling in deeper soil layers, this allows for a higher fill level in the box auger, as a stronger or greater compressed air pulse is available for emptying, since hydrostatic pressure increases with depth.

[0034] In principle, the inventive emptying process using a pressure medium can only be carried out at certain stages during drilling, particularly when soil layers containing cohesive material are encountered. If soil layers containing loose material, such as sandy or gravelly material, are encountered, pressure introduction during emptying can be omitted. However, in principle, any pressure medium present can also be introduced into the receiving chamber at any stage of the emptying process.

[0035] Another advantageous embodiment of the method according to the invention consists in the fact that, to build up pressure of the compressed air, a passage opening in the ceiling of the housing is closed, and that at a further specific time, the passage opening is opened to allow fluid from the receiving chamber to pass through. This ensures that, for example, drilling fluid can flow back out of the receiving chamber during drilling, so that sufficient space remains to collect the excavated soil material.

[0036] A control valve at the through-opening can be operated via a control unit such that, firstly, a sufficient amount of compressed air builds up in the pressure vessel, and secondly, a certain residual amount of fluid remains in the upper part of the receiving chamber between the ceiling and the excavated soil material. Preferably, when emptying the box drill, this chamber is filled only with the excavated soil material and residual drilling fluid immediately before the emptying process, with little or no residual air remaining in the receiving chamber before the introduction of the compressed air.

[0037] The invention is further described below with reference to a preferred embodiment, which is shown schematically in the drawing.

[0038] The only drawing shows a side view of a box drill according to the invention.

[0039] The illustrated box drill 10 according to the invention has a drum-shaped housing 12 with an inner receiving chamber 14. At its top is a generally closed cover 18, to which a central connecting device 27 for a drill string 8 is attached. A torque can be transmitted via the drill string 8 and the connecting device 27 from a carrier device or drilling rig (not shown, but generally known), so that the box drill 10 is set into rotation about the central drilling axis 11.

[0040] On its underside, the drum-shaped housing 12 has a receiving opening 16, which can be closed by means of a hinged bottom 22 with a rotating plate 26 (shown only schematically) that is rotatably mounted about the bore axis 11. A removal device 20 with removal teeth is formed on the hinged bottom 22 in the area of ​​the receiving opening 16.

[0041] When drilling with a first direction of rotation around the drilling axis 11, the receiving opening 16 is open, whereby soil material 4 removed by the removal device 20 together with drilling fluid 6, which may in particular be a support fluid, such as a bentonite fluid, enters the receiving chamber 14 of the drum-shaped housing 12.

[0042] As the drilling depth increases, the air remaining in the receiving chamber 14 is displaced upwards towards the closed ceiling 18 and compressed in the process. This compressed air can be drawn into a pressure vessel 32, which serves as a pressure source 30. For this purpose, the pressure vessel 32 is connected to a valve assembly 16 via a pipe connection 34. When the valve assembly 36 is opened, the compressed air can be drawn in. At a specific time, the valve assembly 36 can be closed again, so that the compressed air is enclosed in the pressure vessel 32.

[0043] To drain excess drilling fluid 6, a through-opening 40 is located in the ceiling 18 of the housing 12, which can be opened and closed via a controllable control valve 42. By opening the control valve 42, excess drilling fluid 6 can escape upwards from the housing 12 until a desired residual layer of drilling fluid 6 remains above the collected excavated soil material 4, as shown schematically in the figure.

[0044] Once the box drill 10 is sufficiently filled with excavated soil material 4, the rotating plate 26 can be turned relative to the hinged base 22 by changing the direction of rotation about the drill axis 11, whereby the rotating plate 26 closes the receiving opening 16 on the hinged base 22. The box drill 10 can then be pulled upwards out of the borehole via the drill rod 8 and moved to the desired emptying position.

[0045] At the emptying position, the lockable hinged bottom 22 can be unlocked, allowing it to fold or pivot downwards around a pivot joint 24 on the housing 12 of the box drill 10. Through the now open underside of the housing 12, the removed soil material 4, along with the remaining drilling fluid 6, can now drain downwards into the receiving chamber 14.

[0046] To assist the emptying process, particularly in the case of cohesive excavated soil material 4, which tends to adhere to an inner wall of the housing 12, the valve assembly 36 can be opened, allowing compressed air from the pressure vessel 32, acting as a pressure source 30, to re-enter the receiving chamber 14. This exerts an additional pressure impulse from above on the contents of the box drill 10, thus further expelling any adhering plug of excavated soil material 4. In particular, the pressure impulse can overcome any existing static friction, allowing the area of ​​lower friction to be reached. The excavated soil material 4, along with the overlying layer of drilling fluid 6, can then exit downwards from the interior 14.

[0047] The presence of a certain layer of drilling fluid 6 when introducing the compressed air from the pressure vessel 32 can improve the most uniform distribution of the compressed air pulse onto the upper side of a plug of excavated soil material 4 in the receiving chamber 14, so that even a relatively small compressed air pulse is sufficient to effect the desired expulsion.

[0048] Immediately after the compressed air pulse, the through-opening 40 can preferably also be opened by opening the control valve 42, so that pressure equalization occurs simultaneously when the plug of soil material exits the drum-shaped housing 12 after the compressed air pulse. This can prevent a vacuum effect that could otherwise make emptying more difficult.

Claims

1. Drilling bucket for creating a drilled hole in the ground, comprising - a drum-shaped housing (12) which comprises an inner receiving space (14) for receiving removed soil material (4), at least one receiving opening (16) on an underside, and a substantially closed lid (18) on the upper side of the housing (12), and - a removal device (20), which is arranged in the region of the underside of the housing (12) and is configured for removing soil material, characterised in that - a pressure source (30) is arranged on an upper region of the housing (12), which pressure source is in line connection with the receiving space (14) of the housing (12) via a valve device (36), and - the valve device (36) is controllable in such a way that the valve device (36) is opened for emptying the receiving space (14) of soil material received during drilling, wherein a pressure medium flows out of the pressure source (30) into the receiving space (14).

2. Drilling bucket according to claim 1, characterised in that the valve device (36) is controllable in such a way that, during drilling out, compressed air that forms is received from the receiving space (14) as pressure medium in a pressure container (32) as a pressure source (30), during drawing of the drilling bucket (10) out of the ground the valve device (36) is closed for enclosing compressed air in the pressure container (32) and for emptying the receiving space (14) of soil material received during drilling the valve device (36) is opened, wherein compressed air flows back into the receiving space (14).

3. Drilling bucket according to claim 1 or 2, characterised in that a hinged base (22) is foldably mounted on the underside of the housing (12), which base is adjustable between a closure position for closing the housing (12) downwards and an open position for emptying the receiving space (14).

4. Drilling bucket according to claim 3, characterised in that the at least one receiving opening 16 is formed on the hinged base (22), and a rotary plate (26) is rotatably mounted on the hinged base (22) for opening and closing the at least one receiving opening (16).

5. Drilling bucket according to claim 4, characterised in that the removal device (20) is arranged on the hinged base (22) and / or the rotary plate (26).

6. Drilling bucket according to any one of claims 1 to 5, characterised in that in addition, a closable passage-opening (40) is provided on the lid (18) of the housing (12), via which opening drilling fluid (6) can emerge out of the receiving space (14) of the housing (12) outwards.

7. Drilling bucket according to claim 6, characterised in that the passage-opening (40) is closable by means of a control valve (42) which is actuatable by a controller.

8. Drilling bucket according to any one of claims 1 to 7, characterised in that an expansion element is arranged in an upper region of the receiving space (14), which expansion element is movable further into the receiving space (14), by the pressure medium, for emptying.

9. Drill comprising a carrier device having a rotary drive, by which a drilling bucket can be rotatably driven for creating a drilled hole in the ground, characterised in that a drilling bucket (10) according to any one of claims 1 to 8 is provided.

10. Drill according to claim 9, characterised in that a controller for controlling the drilling bucket (10) is arranged on the carrier device.

11. Method for creating a drilled hole in the ground using a drilling bucket (10) according to any one of claims 1 to 8, wherein, for emptying the drilling bucket (10) of the soil material, a pressure medium is introduced from the pressure source (30) into the receiving space (14).

12. Method according to claim 11, characterised in that - the drilling bucket (10) is introduced in a rotating manner into the ground, with removal of soil material, - the removed soil material (4) is received in the receiving space (14) of the drilling bucket (10), - during drilling out, a pressure container (32), as the pressure source (30), is filled with compressed air, as the pressure medium, from the receiving space (14), - during drawing of the drilling bucket (10), the pressure container (32) with received compressed air is closed, and - the drilling bucket (10) is emptied of the soil material at an emptying position, wherein the pressure container (32) is opened and compressed air is introduced back into the receiving space (14) for supporting the emptying of the removed soil material (4).

13. Method according to claim 11 or 12, characterised in that the drilled hole is created by repeating a drilling step with introducing of the drilling bucket (10) and drawing of the drilling bucket (10).

14. Method according to claim 12 or 13, characterised in that for building up a pressure of the compressed air a passage-opening (40) on the lid (18) of the housing (12) is closed, and at a further determined timepoint the through-opening (40) is opened for the passage of fluid out of the receiving space (14).

15. Method according to claim 14, characterised in that a control valve (42) on the passage-opening (40) is controlled by the controller in such a way that at the timepoint of the emptying the receiving space (14) is filled with removed soil material and fluid, wherein a liquid layer is formed between the lid (18) and the removed soil material.