Drill tip for a drilling device for creating drill holes in a building foundation

Description

Technical field of the invention

[0001] The present invention relates to a drill bit for a drilling device for creating boreholes in subsoil, in particular subsoil with insufficient bearing capacity. The drill bit can be mounted on a drill tube of the drilling device and detachably connected to the drill tube, the drill tube being closable by a base plate of the drill bit. Extending from a base plate, the drill bit forms a drill point that is driven into the ground by rotation. State of the art

[0002] When constructing a building, it may be necessary to transfer the building's loads to deeper load-bearing soil layers via foundation piles, especially if the subsoil at the building's foundation depth proves to be insufficiently load-bearing and unacceptably large settlements are to be expected.

[0003] To construct foundation or displacement bored piles, a drill bit, also called a drill head or drill tip, is attached to the lower end or insertion end of a steel pipe, hereinafter referred to as a drill pipe. This drill head advantageously seals the drill pipe watertight. The drill pipe and drill tip are secured against rotation and detachably connected. Using a drilling rig, the drill pipe is screwed or possibly driven into the ground to the required depth under high vertical pressure, displacing the soil material largely radially in the volume of the drill pipe. For this purpose, the drill tip can have at least one cutting edge that loosens and displaces the soil material. Once the final depth is reached, prefabricated pile reinforcement, such as a reinforcement cage, can be inserted into the drill pipe, and the drill pipe can then be filled with concrete to create cast-in-place piles.Until the concrete is poured, the extendable drill pipe also serves as support for the surrounding soil. The drill pipe can be withdrawn from the borehole while continuously rotating it, at which point it detaches from the drill bit, which remains in the ground as a lost component. As the drill pipe is withdrawn, the concrete inside it flows into the resulting cavity in the soil, filling it to the required level. After the concrete has hardened, a load-bearing, possibly reinforced, displacement pile is formed.

[0004] Drill bits used in the construction of displacement piles are subject to considerable wear and tear and high stress depending on the soil conditions and, as intended, remain in the ground as so-called lost drill bits. Therefore, the focus is on both a robust and a cost-effective manufacturing process for such drill bits.

[0005] From EP 1 279 793, a drill bit is known which consists of cast steel and is designed as a metallic hollow cone body with a continuously circumferential helical nose around the outer circumference of a tapered threaded core. Until now, drill bits that can be manufactured as castings have been relatively expensive to produce, especially if they are not rotationally symmetrical or simple castings.

[0006] Drill bits are also known, which can be assembled from simply shaped plate-like cast parts or from steel parts that have been previously cut, bent and welded.

[0007] From EP 3 216 974 A1, a drill bit for an earth drilling device is known, comprising a base plate connectable to a drill pipe, onto which at least one drill bit head plate, oriented substantially perpendicular to it, can be mounted. At least one arc-shaped plate can be inserted into the lateral flanks of the drill bit head plate and fastened to it by means of retaining means. The arrangement and shape of the at least one arc-shaped plate are such that its surfaces function as screw surfaces during the drilling process.

[0008] Based on the prior art, the present invention aims to overcome the aforementioned disadvantages and to design a drill bit in such a way that it can be manufactured with little effort and at low cost and can be expanded modularly in order to be adaptable to the respective requirements for creating boreholes.

[0009] Another aspect of the present invention is to provide a tilt-proof drill tip which can be connected to a drill pipe of the drilling device in a rotationally secure and detachable manner, even with an asymmetrical design of the drill tip. Summary of the invention

[0010] According to the present invention, the objectives are achieved primarily through the subject matter of independent claim 1. Further advantageous embodiments are also apparent from the dependent claims.

[0011] In particular, one aspect of the present invention is achieved by a drill bit, also referred to as a drill head, for a drilling device for creating a borehole in a building site, wherein the drill bit can be mounted on a drill pipe of the drilling device and wherein the drill bit comprises a base plate and at least one drill head plate arranged on the base plate and extending substantially perpendicular to the base plate, and can be complemented to form the drill bit with at least one arc-shaped plate, the surface of which forms parts of helical surfaces during drilling. Furthermore, the drill bit comprises connecting means for a detachable connection to the drill pipe, secured against rotation and / or tilting. The base plate and the at least one drill head plate form a single-piece drill head basic shape, which is tapered to a point in a region facing away from the base plate.This basic drill head shape is particularly cost-effective and easy to manufacture using a suitable manufacturing process, and can also be transported to the place of use.

[0012] The drill head basic form is a one-piece or integrally formed basic shape, which can be extended to form the drill tip as required, thus enabling the most wear-free and efficient creation of boreholes in a wide variety of soil types. The drill tip includes at least one arc-shaped plate, the surface of which forms parts of the helical surface during drilling.

[0013] In a preferred embodiment of the drill head, at least the basic drill head shape, comprising the base plate and the at least one drill head plate extending substantially perpendicularly from the base plate, is manufactured by a casting process. Depending on the material of the drill head, a suitable casting process can be selected to produce a robust yet cost-effective drill tip. Other suitable manufacturing processes are conceivable, such as printing processes.

[0014] According to the invention, further individual elements can be inserted into such a basic drill head shape. In other words, the invention provides a drill tip in a basic shape which can be extended by individual elements, regardless of whether arc-shaped plates functioning as screw surfaces are already molded onto the one-piece drill head basic shape or not. In particular, the arc-shaped plates can be arranged and / or designed independently of the requirements of a casting process, whereby drill tips can be manufactured specifically for the respective application.

[0015] In one embodiment, the drill head basic form comprises the base plate and the at least one drill head plate, wherein the at least one arc-shaped plate can be arranged or inserted in a suitable position on the drill head basic form and is secured by means of retaining devices, for example, by positive locking. Alternatively, the at least arc-shaped plate can be arranged and held on the drill head basic form by welding, bolting, or another suitable connection.

[0016] This inventive design of the drill head ensures that the drill tip, set in rotation by the drilling device, penetrates the ground quickly and efficiently via the at least one arc-shaped plate provided between adjacent lateral flanks of the drill head plates, which acts as a helical surface. The resulting time savings are particularly noteworthy when a large number of boreholes and foundation piles are required to support a structure.

[0017] For an even more efficient drilling process, at least one drill head plate can be designed such that its side edges project beyond the circumferential edge of the base plate. The diameter of the base plate corresponds at least to the outer diameter of the drill pipe, so that the protruding edges displace the soil during drilling to such an extent that sufficient clearance is created between the borehole and the drill pipe to minimize friction for the drill pipe within the borehole. This can also be achieved by appropriately shaping the at least one arc-shaped plate.

[0018] To form a drill bit, the at least one drill head plate has a base body that includes a tapered section opposite the base plate. The shape of this tip can be adapted to the soil being drilled. Therefore, the shape of the base body of the at least one drill head plate can be adjusted depending on the soil conditions. It has proven particularly advantageous for the tip to be asymmetrical, as this allows for a displacement effect in addition to the at least one arc-shaped plate.

[0019] In a further embodiment according to the invention, a first drill head plate and a second drill head plate, oriented essentially at right angles to it, are provided on the base plate, integrally forming the basic drill head shape. Alternatively, such a second drill head plate can also be used as an individual element and secured by suitable means. The crosswise arrangement of the first and second drill head plates results in a stable drill head structure, which also provides extended modulation for the arrangement of one or more arc-shaped plates.

[0020] In one embodiment of the present invention, a first arc-shaped plate can be inserted between two adjacent flanks of the drill head plates and a second arc-shaped plate can be arranged opposite between corresponding flanks.

[0021] Advantageously, in a crosswise arrangement of the first and second drill head plates, an arc-shaped plate can extend over one flank of the first drill head plate and an adjacent flank of the second drill head plate, and a second arc-shaped plate can extend over the opposite side. In particular, both arc-shaped plates can be of a similar design. The somewhat symmetrical arrangement of the two arc-shaped plates forms a drill head which, in operation, exhibits a low tendency to tilt, thus preventing unintentional detachment from the drill pipe during the drilling process.

[0022] Furthermore, in the area of ​​the tip formed on the side facing away from the base plate, in the tapered area, a third arc-shaped plate can be arranged, which further improves the efficiency of the drilling process.

[0023] Furthermore, it can be provided that the at least one arc-shaped plate arranged or arrangable on the drill head base has at least a partial outer diameter larger than the outer diameter of the base plate, so that the at least one arc-shaped plate has an edge region that projects at least partially beyond the base plate. Accordingly, the outer edge of the arc-shaped plate runs at a varying distance from a drilling axis. This ensures that the helical surfaces formed by the at least one arc-shaped plate can be effectively used to radially displace the soil.

[0024] The drill bit according to the invention ensures that, thanks to the expandability of the basic drill bit shape, it can be adapted to the requirements and specific characteristics of the subsoil and the drilling task. At the same time, the small number of shapes required results in low manufacturing costs, straightforward transport to the site, and rapid adaptation of the drill head's basic shape. It is particularly advantageous if the at least one arc-shaped plate is manufactured by cutting it from a standard steel plate or another suitable material and can be inserted into the drill head's basic shape or at least one drill head plate. This keeps costs low while simultaneously allowing for a wide range of drill head modifications to adapt to the specific conditions on site.

[0025] If at least one arc-shaped plate is designed as an individual element, it can be inserted into and held on the drill head plate(s) by means of complementary retaining means. In particular, the retaining means can be designed as projections and slot-shaped recesses.

[0026] The combination of a drill head base and its extension using one or more arc-shaped plates proves highly advantageous in terms of both versatility and cost. Because the number, shape, size, and potentially even the material of the arc-shaped plates can be selected, the drill bit can be adapted to specific soil conditions, while the drill head base simultaneously provides a stable and reliable foundation. The design of the drill head base, manufactured in one piece using a single process, can vary, ranging from a base plate and a drill head plate to a form consisting of a base plate, several drill head plates, and at least one arc-shaped plate.

[0027] The invention also relates to the provision of connecting means for the drill bit to a drill pipe in a twist-proof and / or tilt-proof, detachable manner, in order to optimally transfer the rotational movement of the drill pipe to the drill head and to prevent the drill bit from tilting relative to the drill pipe. The connecting means with which the drill bit can be connected to the drill pipe can, for example, be designed as projections extending from the base plate. To connect the drill bit to the drill pipe, slots are provided at the end of the drill pipe into which the projections of the base plate extend. Furthermore, to prevent the drill bit from tilting relative to the drill pipe, i.e., being forced into a position oblique to the drilling axis, the projections or webs or segments can have an approximate L-shape.In this design, one leg of the connecting element extends almost vertically from the base plate over a definable length, forming a contact surface with the inner circumference of the drill pipe. Other connecting element designs are conceivable, for example, in the form of webs that are designed to create a rotationally secure and detachable connection with the drill pipe and, at the same time, a contact or guide surface on the inner circumference of the drill pipe. The number and design of the connecting elements can vary. It is also possible to connect individual connecting elements to each other for further stabilization using ring-shaped elements or similar components. This allows the rotational movement of the drill pipe to be transferred to the drill tip in an optimal and, in particular, tilt-proof manner. Suitable connecting elements can be integrally formed with the base plate of the drill head or designed as individual components that can be connected to it.

[0028] Further details of the invention will become apparent from the following description of preferred embodiments of the device according to the invention, which are illustrated by way of example in the accompanying drawings. The description will also reveal the further advantages of the present invention, as well as suggestions and proposals on how the subject matter of the invention can be modified or further developed within the scope of the claim. Brief description of the drawings

[0029] They show: Figure 1 a schematic side view of a drill bit; Figure 2 a schematic side view of a first embodiment of a drill bit according to the invention; Figure 3 a schematic perspective representation of a second embodiment of a drill bit according to the invention; Figure 4 a schematic perspective representation of a third embodiment of a drill bit according to the invention; Figure 5a schematic top view of an embodiment of an arc-shaped plate and of a drill tip head plate; Figure 6 A schematic detail view of an anti-tilt device for connecting the drill bit to a drill pipe. Preferred embodiments of the invention

[0030] Out of Figure 1 A drill bit 1 is visible, which has a drill head shape 2. The drill head shape 2 has a base plate 3 and at least one drill head plate 4 extending substantially perpendicular to the base plate 3. Of course, instead of the single drill head plate 4 shown, several drill head plates 4 can be provided. For example, two drill head plates 4 arranged at right angles to each other can be arranged. The drill head shape 2 can be manufactured as a single piece using a suitable manufacturing process, in particular by a casting process, and thus forms a casting.

[0031] The at least one drill head plate 4 is tapered to a point in the area facing away from the base plate 3, thus forming a point 10. The basic drill head shape 2 is detachably connected to a distal end region of a drill tube 5 (not shown), as will be described later. The drill tube 5 is driven in a known manner by a drilling device (not shown) rotating it about a drilling axis 6 and pressed into the borehole.

[0032] As in Figure 1As shown, the drill tip 1 comprises at least one arcuate plate 7, which is provided on the drill head base 2 such that it acts as a helical surface during the drilling process. A drill tip 1 known per se is shown with an arcuate plate 7, which is integrally formed with the drill head plate 4. The integrally formed arcuate plate 7 is positioned on the drill head base 2 such that it forms a helix angle α with respect to the drilling axis 6. The degree of the helix angle α can be in a range of 10° to 30°. In the illustrated embodiment, the helix angle α is approximately 20°, but can be varied to be optimally adjusted depending on the soil conditions. This increases the efficiency of the drilling process.

[0033] From the Figure 2A first embodiment of the drill head 1 according to the invention is shown. Here, the basic drill head form 2 comprises the base plate 3 and a first drill head plate 4a and a second drill head plate 4b, which are integrally formed with the base plate 3 and arranged at right angles to each other. The shape of the tip 10 of the drill bit 1 can be formed by a base body 40 of the first drill head plate 4a and / or the second drill head plate 4b and extends along the drilling axis 6. The base body 40 of the at least one drill head plate 4a can be designed such that a more rectangular section and an adjoining tapered section or area are formed. However, it is also conceivable that the base body 40 of the at least one drill head plate 4 has an overall approximate triangular shape with the tip 10.Furthermore, it is shown that the at least one arc-shaped plate 7 can be inserted into the drill head base 2. Such insertion is particularly advantageous when the design of the arc-shaped plate 7 is selected to suit the ground conditions.

[0034] In the illustrated second embodiment of the drill bit 1 of the Figure 3An integrally formed arc-shaped plate 7a is shown, extending between a flank 9a of the first drill head plate 4a and up to a flank 11a of the second drill head plate 4b. In this embodiment, the arc-shaped plate 7a is integrally formed with the drill head base plate 2, i.e., it is not insertable. Symmetrically to the first arc-shaped plate 7a, a second arc-shaped plate 7b is inserted into the first drill head plate 4a and into the second drill head plate 4b, preferably being designed identically to the first arc-shaped plate 7a. To hold insertable arc-shaped plates 7, for example, the second arc-shaped plate 7b, retaining means 12 are provided or formed on it, which are configured to engage with retaining means 13 (not shown) provided complementarily on the respective drill head plates 4a and 4b in order to hold the second arc-shaped plate 7b in position.A drill tip 1 with insertable and molded arc-shaped plates 7 expands the variation possibilities of the drill tip 1.

[0035] Furthermore, it is shown that the radial distance of an outer edge 8 of the arc-shaped plates 7 to the drilling axis 6 is variable. The molded plate 7a is designed such that the radial distance of its outer edge to the drilling axis 6 increases from the area where the arc-shaped plate 7a is molded onto the flank 11a of the drill head plate 4b to the area where the arc-shaped plate 7a is molded onto the flank 9a of the drill head plate 4a. A similar principle applies to the insertable arc-shaped plate 7b.

[0036] Further embodiments provide that the arc-shaped plates 7a and 7b are individual elements which can be combined with the basic drill head shape 2 to adapt the drill tip 1 according to the prevailing conditions. The symmetrical arrangement and comparable design of the arc-shaped plates 7a and 7b provide a drill tip 1 which exhibits smooth rotation and is largely resistant to buckling during the drilling process.

[0037] In Figure 4A third embodiment of the drill tip 1 according to the invention is shown, wherein a total of three arc-shaped plates 7a, 7b, and 7c can be combined with the drill head base form 2. In particular, the third arc-shaped plate 7c can be inserted and held in a position located in the region of the tip 10. It is possible that at least one of the arc-shaped plates 7 is integrally formed on the drill head base form 2, and that the second arc-shaped plate 7b and / or a third arc-shaped plate 7c can be inserted into the drill head base form 2. Variants are also possible, for example, if all arc-shaped plates 7 are designed to be insertable.

[0038] In Figure 5An arc-shaped plate 7, which can be inserted into the drill head base 2, and a drill head plate 4 are shown. The arc-shaped plate 7, shown as an individually insertable part, is equipped with retaining means 12. These retaining means 12 comprise projections 22. Complementary retaining means 13 (not shown), which are provided on the at least one drill head plate 4 as shown, are designed as recesses 23, for example as slot-shaped recesses 23 on the flank or as a recess 23 in the base body 40. To position the arc-shaped plate 7 on the drill head base 2, i.e., on the drill head plate 4, the projections 22 and the recesses 23 are engaged so that a varying number of arc-shaped plates 7 with their retaining means 12 can be hooked or inserted into the retaining means 13 of the drill head plates 4.In the illustrated embodiment, the arc-shaped plate 7 is formed with a nose 24 which, when the arc-shaped plate 7 is inserted, encloses the drill head plate 4. This allows for optimized support of the arc-shaped plate 7 relative to the drill head plate 4. Alternatively or additionally, a shoulder 25 can be formed on the arc-shaped plate 7, which, when the arc-shaped plate 7 is inserted, rests against the drill head plate 4 and thus supports it during the drilling process. The drill tip 1 designed in this way exhibits optimal resistance to bending.

[0039] In Figure 6Details of the connection between the drill tip 1 and the distal end of the drill pipe 5 are shown. The drill tip 1 therefore includes connecting elements 30 for a rotationally secure and detachable connection with the drill pipe 5, in order to optimally transfer the rotational movement of the drill pipe 5 to the drill tip 1 and to prevent the drill tip 1 from tilting relative to the drill pipe 5. The connecting elements 30, with which the drill tip 1 can be connected to the drill pipe 5, are shown in Figure 6 formed as L-shaped projections 31 with projecting legs 32 extending from the base plate 3.

[0040] To connect the drill bit 1 to the drill pipe 5, slots are provided at the end of the drill pipe 5 into which the L-shaped projections 31 extend. Furthermore, to prevent the drill bit 1 from tilting relative to the drill pipe 5, i.e., being forced into a position oblique to the drilling axis 6, one of the legs 32 projects almost vertically from the base plate 3 over a length 33, thus forming a contact surface with the inner circumference of the drill pipe 5.

[0041] The number and design of the fasteners can vary. Figure 6 Four evenly distributed connecting elements 30 are shown.

Claims

1. Drill head (1) for a drilling rig for creating a drill hole in a building substrate, whereby the drill head (1) is able to be fitted onto a drill pipe (5) of the drilling rig, and the drill head (1) comprises a base plate (3) and at least one drill head plate (4) arranged on the base plate (3) and extending substantially perpendicular to the base plate (3), characterized in that the drill head plate (4) and the base plate (3) form a drill head basic shape (2) designed in one piece, which is designed tapering to a point in a region facing away from the base plate (3), and that the drill head comprises at least one arcuate plate (7), which is designed such that its surface forms portions of screw surfaces during drilling, and comprises connecting means (30) which project from the base plate (3) in a direction opposite to the at least one drill head plate (4) in order to form a releasable connection, secured against rotation and / or tilting, of the drill head (1) able to be fitted on the drill pipe (5).

2. Drill head according to claim 1, characterized in that the drill head basic shape (2) is able to be produced by means of a casting process.

3. Drill head (1) according to claim 1 or 2, characterized in that at least one arcuate plate (7) is able to be arranged as an individual element on the drill head basic shape (2) and is held in place by retaining means (12; 13).

4. Drill head (1) according to one of the preceding claims, characterized in that the at least one drill head plate (4) has a base body (40) that is asymmetrical with respect to a drilling axis (6).

5. Drill head (1) according to one of the preceding claims, characterized in that the drill head basic shape (2) comprises a first drill head plate (4a) and a second drill head plate (4b) arranged substantially at right angles thereto.

6. Drill head (1) according to one of the preceding claims, characterized in that the at least one arcuate plate (7) extends at least from one side edge (9) of the drill head plate (4) to an adjacent side edge (9).

7. Drill head (1) according to one of the preceding claims, characterized in that a first arcuate plate (7a) and opposite it, a second arcuate plate (7b) are provided.

8. Drill head (1) according to claim 7, characterized in that a third arcuate plate (7c) is provided, which is situated in the tapered section of the drill head basic shape (2).

9. Drill head (1) according to one of the preceding claims, characterized in that the outer edge of the provided at least one arcuate plate (7) runs at a varying distance from the drilling axis (6).

10. Drill head (1) according to one of the claims 3 to 9, characterized in that the retaining means (12) on the arcuate plate (7) are formed as projections (22) and the retaining means (13) on the drill head plate (4) are formed as slot-shaped recesses (23), which are able to be brought into engagement with one another.

11. Drill head (1) according to one of the preceding claims, characterized in that the connecting means (30) are designed as at least two lobes projecting from the base plate (3), which are able to be brought into engagement with recesses on the distal end region of the drill pipe (5).

12. Drill head (1) according to one of the preceding claims, characterized in that the connecting means (30) are configured to form the one support surface with an inner circumference of the drill pipe (5).

13. Drill head (1) according to claim 12, characterized in that the connecting means (30) are formed as L-shaped projections (31), whereby a leg (32) projecting perpendicularly from the base plate (3) by a length (33) forms the support surface with an inner circumference of the drill pipe (5).

14. Drill head (1) according to one of the preceding claims, characterized in that the connecting means (30) are moulded onto the base plate (3).