Drill head for a percussive displacement earth drill and using a drill head for a percussive displacement earth drill

Description

[0001] The invention relates to a drill head for a self-propelled impact device as a percussive displacement earth drilling device and earth drilling device.

[0002] Earth drilling devices are known for creating boreholes in the ground; these can be designed, for example, as a ramming drill or ramming device.

[0003] DE 25 58 842 A1 discloses a ramming drill with a displacement cone, the outer circumference of which is formed with knife-like cutting edges that very quickly shatter solid obstacles, such as stones. The knife-like cutting edges can be arranged in a stepped, offset arrangement. A ramming drill is described that has a tubular housing and a striking tip mounted axially displaceably within it. The striking tip has a forward-tapering displacement cone in its area outside the housing, which sits on a conical intermediate section of the striking tip with a central bearing bore. The striking tip, which can be designed, for example, as a hollow chisel, is pushed forward together with the displacement cone when impact is applied from behind.While the chisel-like part of the impact tip serves to crush stones, the displacement cone's function is to laterally divert the soil and form a cavity with compacted side walls, so that a solid channel is formed during the movement of the ram drill. The displacement cone can essentially be described as a stepped head or stepped drill head, as also known from DE 101 12 985 A1.

[0004] DE 10 2004 032 551 A1 discloses a drill head for creating or widening a borehole using a percussive drilling device. A drill head with two sections is described. The first section has drainage channels and can be used to loosen the soil or to crush obstacles. The second section has conical sections on its surface and can provide radial compaction of the loosened soil. The first section can essentially be described as a crown head or crown drill head, which has cutting edges extending transversely to the longitudinal extent of the drill head, between which drainage channels are provided for conveying the drill cuttings or fragments of the crushed obstacles.

[0005] WO 2006 / 002997 A1 discloses a drill head for an earth drilling rig, in which a first drill head section has drainage channels. A second drill head section following the first drill head section has one or more largely conical sections on its outer surface. WO 2006 / 002997 A1 describes a largely conical shape as, in particular, a outer surface that rises—at least partially—from a small radial extent, "continuously" to a larger radial extent, and thus has no sections within the conical area where the radius decreases again.

[0006] EP 2 663 726 A1 discloses an earth drilling device in which a section of the drill head can be separated from the body of the drill head to form a channel. Soil can pass through the channel from one side of the earth drilling device to the other, thereby tilting the drill head by means of the displaced soil. An embodiment is described in which a first drill head section has stepped areas, and a drill head section following the stepped areas has the capability to form the channel when the head area is separated from the body of the drill head.

[0007] EP 0 548 588 A1 discloses a device for producing earth boreholes. A displacement head is described, the outer diameter of which is larger than the outer diameter of the drive unit and the surrounding pipe. Fig. 2EP 0 548 588 A1 shows a stepped displacement head having grooves extending from front to back along the displacement head in which liquid jet nozzles are arranged one behind the other.

[0008] US 738 327 A discloses a drill and a reamer that is removable from the drill body, wherein the drill body has a reduced diameter at the connection points with the reamer in order to be able to engage with a tool at these points to join the reamer and drill body together.

[0009] Although known earth drilling devices show good results in drilling earth boreholes, it is an object of the invention to create an improved drill head for an earth drilling device or an improved use of a drill head for an earth drilling device, in which an improvement in performance for creating an earth borehole and / or an improvement in the service life of the drill head can be achieved.

[0010] The problem is solved according to the subject matter of the independent patent claims. Advantageous embodiments are the subject matter of the respective dependent claims and the description.

[0011] The core concept of the invention is to provide a combination in which one drill head section is designed as a crown head and another as a stepped head. Despite the previously considered, incompatible alternatives of either a crown head or a stepped head, it was recognized that the drill cuttings, for example, in the form of stones or (clumped) soil, etc., can be rotated or pressed outwards into the borehole wall by means of the steps of the stepped head. It was recognized for the first time that the solid parts can be "levered" into the borehole wall. The drill head section designed as a crown head can break up existing obstacles, such as stones, and then the fragments of these obstacles can be levered outwards into the borehole wall by means of the steps of the drill head section designed as a stepped head.According to a key concept of the invention, the drill head section, designed as a crown head, can first cut through the soil. Obstacles in the form of rock that are larger than the openings / discharge channels in the crown head can be crushed. This allows only correspondingly small obstacles to be screwed or levered into the soil, thus keeping the reaction forces that could cause the drill head to deflect low. Since the obstacles can be screwed in behind the drill head section designed as a crown head, the leading section of the drill head designed as a crown head can also serve as a guide, thereby improving the directional stability of the drill head.

[0012] A drill head for a percussive displacement earth drilling device according to claim 1 is provided, comprising a first and a second drill head section. The first drill head section has discharge channels, and the second drill head section has a cross-section that increases longitudinally. The second drill head section has several stepped sections.

[0013] The invention provides added value for the user of the drill head or an earth drilling device incorporating the drill head by reducing the skin friction on the housing of the drill head, which follows the two drill head sections. This reduces the negative effects on the performance and advance of the earth drilling device that would otherwise be caused by increased skin friction. Likewise, wear on the housing following the two drill head sections can be reduced. The drill head section designed as a crown head can perform the work of removing obstacles along the borehole being created, and the steps of the drill head section designed as a stepped head convey the fragments of the obstacles outwards into the borehole wall and can, in particular, lever them into the borehole wall by levering or rotating a fragment caught by a step into the borehole wall.This achieves a reduction in shell friction on the downstream housing and / or a reduction in wear on the downstream housing in the simplest way.

[0014] For the purposes of this description, the term "earth drilling device" encompasses any device that moves a drill string, particularly one comprising drill sections, within an existing or planned channel in the ground to create or enlarge a borehole, especially a horizontal borehole (HD), or to install pipelines or other long objects in the ground. The earth drilling device may, in particular, be an HD device. Thus, an earth drilling device can be a device that drives a drill string, displacing soil and driving the drill string translationally and / or rotationally into the ground along its longitudinal axis. A borehole can be created or enlarged by moving the drill string forward and / or backward through the ground. The outer boundary of the channel or borehole is usually referred to as the borehole wall.The drill string can include the drill head and associated sections that are moved through the ground together with the drill head.

[0015] The term "HD" (horizontal drilling) as used in this description includes in particular a borehole or conduit or pipeline that is at least partially arranged horizontally.

[0016] The term "soil" as used in this description includes in particular any type of material, especially earth, sand, rock, stone and mixtures thereof, into which existing or to be created, preferably at least partially horizontal channels or boreholes, in particular earth channels including earth boreholes, rock boreholes or earth conduits as well as underground or above-ground pipelines and water channels, which can be produced or inserted by using a suitable device for drilling in the soil, can be inserted.

[0017] A percussive displacement earth drilling device can be designed as a ram drilling device. The term "ram drilling device" or "earth rocket," which is essentially synonymous with the term ram drilling device, encompasses, in the context of this description, a self-propelled impact device that displaces soil and can drive a borehole, conduit, and / or pipe into the ground. The term "ram drilling device" includes earth displacement devices in which a drill bit can be arranged to move longitudinally within a housing. Alternatively, a drill bit can be rigidly arranged within the housing. The drill bit can be, in particular, a chisel. A ram drilling device can be either a single-stroke device or a multi-stroke device, especially a two-stroke device.In a single-stroke device, the impact piston strikes the drill bit tip and, simultaneously, the housing. In a multi-stroke device, particularly a two-stroke device, where the drill bit tip can be longitudinally movable within the housing, the impact piston first strikes the drill bit tip, which moves ahead in the first stroke. The housing is then impacted by the impact piston in a subsequent stroke, particularly the second stroke. Tip resistance and shell friction are handled separately and overcome more easily in a multi-stroke device. A multi-stroke device, especially a two-stroke device, allows for better energy conversion, which facilitates the shattering of obstacles due to the concentration of the impact impulse on the drill bit tip.As a result of the soil displacement preceding the stroke of the drill head tip, the housing remains in a stable position, thus ensuring relatively good running stability.

[0018] The term "drill head" as used in this description refers to an end-mounted section, unit, or element that has an outwardly directed or exposed end which comes into contact with the soil during drilling. The drill head forms the front section of the drill string, which is the first part of the borehole to come into contact with the soil being displaced, provided the drill string is moving forward. The outwardly directed end of the drill head may have a striking tip or drill bit, particularly in the form of a chisel. The striking tip may have a stepped geometry and preferably a cutting edge.

[0019] The term "drill head section" as used in this description comprises a section of the drill head that extends in one direction along the longitudinal axis of the drill head. A drill head section as defined in this description is characterized by its functionality in creating the borehole, and essentially two drill head sections can be distinguished. The multiple drill head sections are arranged one behind the other, particularly with respect to the longitudinal axis of the drill head. One of the drill head sections can be designed as a crown head section and one as a stepped head section. In a preferred embodiment, exactly two drill head sections are provided, one of which is a stepped head section and the other a crown head section. The crown head section is arranged upstream of the stepped head section in the direction of advancement or forward movement of the drilling device.

[0020] For the purposes of this description, the term "drainage channel" refers to a space arranged between two projections that allows the removal of drill cuttings or excavated soil, essentially along the longitudinal axis of the drill head. The drill cuttings can be conveyed along the drill head via a drainage channel. Relative movement between the soil and the drill head is possible through this drainage channel.

[0021] The term "along" the longitudinal axis of the drill head shall in particular be understood to mean a direction which forms an angle of < 90° with the longitudinal axis of the drill head, preferably between 0° and 45°, more preferably between 0° and 30°.

[0022] The projections can extend in one direction along the longitudinal axis of the drill head, wherein the projections have a section extending at an angle of less than 90° to the longitudinal axis, preferably at an angle of 0° to 45°, more preferably 0° to 30° to the longitudinal axis of the drill head. The projections can have a section extending substantially transversely to the longitudinal axis, wherein the projections can extend radially from the longitudinal axis with this section. Thus, the projections and the spaces or drainage channels arranged between the projections can, with respect to a cross-section through the longitudinal axis, extend radially away from the longitudinal axis, particularly in the form of an end face, and also run along the longitudinal axis. The shape of the projection can change along the longitudinal axis. The drainage channel between two projections can have a constant or varying shape.In particular, the bottom of the discharge channel may have an incline when viewed longitudinally along the drill head. In cross-section, the bottom of the discharge channel may be rounded between two adjacent projections.

[0023] For the purposes of this description, the term "stepped section" refers to a drill head section whose circumference varies. A stepped section comprises at least two areas with diameters differing from the drill head tip, such that the diameter closest to the tip is smaller than the diameter further away from the drill head tip. These differing circumferences can thus form at least two plateaus, which can run substantially parallel to the longitudinal axis, with inclinations to the longitudinal axis ranging from 0° to 40°, preferably 0° to 30°, more preferably 0° to 20°, and more preferably 0° to 10°.Between the plateaus, a surface extending transversely to the longitudinal axis, which can define a step height, is provided. This surface forms an angle of 10° to 90°, preferably 20° to 90°, preferably 30° to 90°, preferably 40° to 90°, preferably 50° to 90°, preferably 60° to 90°, preferably 70° to 90°, and preferably 80° to 90° with the longitudinal axis. The at least two circumferentially extending sections, particularly in the form of plateaus, form a region with a surface extending along the longitudinal axis and circumferentially, which can be considered a tread, analogous to a stair step. Between the surfaces extends a section, referred to as the riser, which runs circumferentially transversely to the longitudinal axis of the drill head. This circumferentially extending section transversely to the longitudinal axis of the drill head essentially constitutes a step height.

[0024] It is described that the steps of the step head can be formed completely around the longitudinal axis of the drill head, so that drill cuttings or debris guided through a discharge channel and landing on the step(s) of a step section located behind a crown head section can be twisted or levered into the wall of the borehole. In particular, the step head section can have a step that can be formed completely around the longitudinal axis. By forming the steps completely around the entire circumference, every drill cutting or debris can be captured by the step head section. It is provided that a step head section arranged longitudinally is located behind a discharge channel of the crown head section. Behind the discharge channel, the drill cuttings can be deflected into the wall of the borehole.The material pulverized by the crown head section can be directed into the discharge channel, strike the step of the stepped head section, and be pressed into the wall of the borehole. For the geometric design of the drill head, this can mean that a stepped head section with its step can be positioned behind a discharge channel (corresponding to the angle of the discharge channel); drill cuttings conveyed through the discharge channel can be captured by the stepped head section.

[0025] In a preferred embodiment, the stepped sections are designed without cutting edges in the circumferential and / or radial direction. This ensures that the fragments or shattered obstacles are not further crushed or broken up within the stepped drill head section, but rather rotated into the inner wall of the borehole or bore channel. This allows for a substantially clear separation between the crushing action of the front drill head section and the displacement action of the subsequent drill head section.

[0026] In a preferred embodiment, two stepped sections are present in the second drill head section. It has surprisingly been found that an insufficient step height, i.e., the radially extending distance between the two plateaus of the two steps, leads to the accumulation of drill cuttings at the area connecting the two steps (step height), i.e., the radially extending area, and the steps become clogged, potentially forming a directionally unstable, conical head. With an insufficient step height, which would be particularly advantageous for a lever, even small rock inclusions are sufficient to deflect the drill head from the desired direction.Given that reducing the number of steps, which leads to an increase in step height, contradicts the original approach of rotating the drill cuttings into the borehole wall, the number of steps can represent a significant—if not independent—aspect of the invention. Alternatively, the second drill head section may have more than two step-shaped areas. If more than two step-shaped areas are present, three or four step-shaped areas are preferred.

[0027] In a preferred embodiment, the stepped sections have essentially the same step heights, which allows for a particularly simple design of the second drill head section. Furthermore, the equal step heights can be distributed such that neither of the two possible step heights is too small.

[0028] In a preferred embodiment, at least one—preferably several, and particularly preferably all—of the stepped sections has a step height that, relative to the diameter of the housing of the earth drilling device, in particular the housing of a ram drilling device, is at least 4% of the housing diameter, preferably at least 5%, more preferably at least 6%, more preferably at least 7%, more preferably at least 8%, more preferably at least 9%, more preferably at least 10%, more preferably at least 11%, more preferably at least 12%, more preferably at least 13%, more preferably at least 14%, and more preferably at least 15%. This addresses the concern of avoiding a step height that is too small, which could become clogged with drill cuttings and thus lead to a directionally unstable drill head section.

[0029] In a preferred embodiment, at least one – preferably several, and in particular preferably all – of the stepped areas has a step length or plateau length or tread which, with reference to the diameter of the housing of the earth drilling device, in particular the housing of a ram drilling device, is at least 5% of the diameter of the housing, preferably at least 7%, more preferably at least 10%, more preferably at least 12%, more preferably at least 15%, more preferably at least 17%, more preferably at least 20%, and more preferably at least 25%, so that a separation of the stepped areas can take place which does not lead to a cancellation or connection of the stepped areas even in the case of deposits or contamination.A corresponding step length can improve the rotation of individual fragments, which should preferably be done in steps, since otherwise the fragments can be captured simultaneously by several step-shaped areas.

[0030] In a preferred embodiment, the final stepped section, spaced from the exposed end of the drill head (i.e., the drill head tip), extends beyond the diameter of a subsequent section of the drill string. This ensures that the stepped section furthest from the drill head tip, and thus the final stepped section in the direction of advance, has an outer diameter that exceeds, in particular, the outer diameter of the housing of the earth drilling device, especially the housing of an earth drilling device configured as a ram drill within the drill string. This reduces the housing friction and thereby increases the drilling performance, resulting in added value for the user. In addition to improved drilling performance, maintenance of the earth drilling device itself is reduced, and its service life is extended.In a preferred embodiment, the diameter of the last stepped section is 5% larger than the diameter of a subsequent section of the drill string, in particular the housing of the earth drilling device designed as a ram drilling device, preferably 7% larger, more preferably 10% larger, and even more preferably 12% larger than the diameter of the housing.

[0031] In a preferred embodiment, at least one of the projections defining a discharge channel extends beyond the diameter of the second drill head section and / or a subsequent section of the drill string. This allows the projections, acting as cutting edges of the first drill head section, to have a larger diameter than the second drill head section. This has the advantage that the at least one projection can move through the soil like a plow and "scrape" the borehole wall, making it easier for the drill cuttings to subsequently become embedded in the borehole wall. By moving through the soil beyond the boundaries of the actual borehole, the borehole wall is loosened, at least in these areas, and the drill cuttings, which essentially correspond to the entire volume of the drill head, can be more easily introduced into the borehole wall.In a preferred embodiment, the diameter with the projections is 5% larger than the diameter of the second drill head section, preferably 7% larger, more preferably 10% larger, and still more preferably 12% larger.

[0032] In a preferred embodiment, at least four, preferably six, projections are provided, forming four or six discharge channels. This generally allows for very good advance performance, enabling sufficient crushing of any rock fragments or obstacles. Four projections are advantageous when a smaller frontal area and fewer lateral friction surfaces can improve advancement while maintaining the same impact performance, as is the case, for example, with loose soil (such as sand or clay). With harder soil, six projections with a larger frontal area and more lateral friction surface are preferable.

[0033] The step height ("slope") is less than one-third the width of a discharge channel. This allows for a suitable dimension to be set, where the step height for rotating the fragments or shattered obstacles into the borehole wall can be adjusted to the size of the fragments or shattered obstacles. This allows the edge of the stepped sections or the tipping edge of a fragment to be positioned such that the tipping edge lies substantially below the center point / center of gravity of a fragment. In a preferred embodiment, the step height can be combined with, or alternatively to, the aforementioned maximum step height, a minimum step height of 1 / 20 of the width of a discharge channel.It can be provided that the size of the step height, relative to the width of a discharge channel, is in a range of 1 / 20 to 1 / 3 of the width of the discharge channel, more preferably in a range of 1 / 18 to 1 / 3, more preferably in a range of 1 / 16 to 1 / 3, more preferably in a range of 1 / 14 to 1 / 3, more preferably in a range of 1 / 12 to 1 / 3, more preferably in a range of 1 / 10 to 1 / 3, more preferably in a range of 1 / 8 to 1 / 3, more preferably in a range of 1 / 6 to 1 / 3, more preferably in a range of 1 / 5 to 1 / 3, and more preferably in a range of 1 / 4 to 1 / 3.

[0034] It is also described how to use a drill head for a percussive displacement earth drilling device with a first and a second drill head section, wherein the first drill head section is a drill head section with discharge channels that destroys obstacles, and the second drill head section is a drill head section that has a longitudinally increasing cross-section, wherein the second drill head section uses several stepped areas that can be used to rotate and / or turn debris of the obstacles into the borehole wall.

[0035] For the purposes of this description, the mention of relative values ​​relating to another quantity, which is given as a percentage or as a fraction of a reference quantity, includes not only the actual resulting numerical value, but also – in order to take into account tolerances caused in particular by manufacturing technology – a range around the resulting specific numerical value, if one uses the reference quantity, which may be + / - 15%, preferably + / - 10%, of the resulting numerical value.

[0036] The term "aufweisen" (to exhibit) encompasses, in the sense of the description, both the inherent meaning of the term, that further elements may be provided in addition to the elements mentioned (non-exhaustive list), but also the meaning that the term "aufweisen" is used synonymously with "consist of" or "formed of" (exhaustive list).

[0037] The foregoing statements, as well as the following description of exemplary embodiments, do not constitute a waiver of certain embodiments or features.

[0038] The invention is explained in more detail below by way of example with reference to embodiments shown in the figures.

[0039] The drawings show: Fig. 1 a front area of ​​a drill head in a longitudinal section (a) and a front view (b), in which the shattering of an obstacle is shown by way of example using a fragment of an obstacle; Figs. 2 to 4 the longitudinal section (a) and the front view (b) according to Fig. 1 with the further movement of the debris; and Fig. 5 Another embodiment of a drill head shown from the front in a longitudinal section and in a front view.

[0040] The Figure 1Figure 1 shows a longitudinal section (a) and a front view (b) of a front section of a drill head 1 for a percussive displacement earth drilling device. The drill head 1 has a housing 2 in which a drill tip 3 in the form of a chisel is arranged. A first and a second drill head section 4, 5 are arranged around the drill tip 3 at the front of the drill head 1. The drill head sections 4, 5 are formed integrally as a projection on the drill head 1. The first drill head section 4 has discharge channels 6. The second drill head section 5 has a cross-section that increases in the longitudinal direction L. The second drill head section 5 also has several stepped sections 7, 8.

[0041] The stepped areas 7, 8 are designed without cutting edges in the circumferential and radial directions R. The stepped areas have step heights H1 and H2 and step lengths SL1 and SL2.

[0042] The Figure 1 Figure 1 shows how the first drill head section 4 shatters an existing obstacle and a fragment of the obstacle passes through one of the discharge channels 6 in the longitudinal direction L of the drill head 1 as the drill head 1 moves. When the fragment reaches a step of the stepped sections 7, 8, the fragment is removed according to the procedure shown in Figure 1. Figure 2 The arrow shown was rotated and essentially screwed into the borehole wall. The screwing or levering in of the obstacle fragment is described in the Figures 2 and 3 shown for each of the two levels. In Figure 4 It is indicated that the fragment of the obstacle was embedded or screwed into the borehole wall.

[0043] The one in Figure 5 The embodiment shown differs essentially from the one described in the Figures 1 to 4In the illustrated embodiments, the projections 9 of the first drill head section 4, which delimit the discharge channels 6, extend beyond the circumference or diameter of the second drill head section 5. Furthermore, the second drill head section 5 extends beyond the circumference or diameter of the housing 2, whereas in an embodiment not shown, the second drill head section 5 does not extend beyond the circumference or diameter of the housing 2 and therefore has essentially the same or a smaller circumference or diameter as the housing 2.

[0044] In the Figure 5 The diameter D4 of the first drill head section 4, formed by the projections 9, is approximately 5% larger than the diameter D5 of the second drill head section 5. The diameter D5 of the second drill head section 5 is approximately 5% larger than the diameter D6 of the housing 2.

Claims

1. Drilling head (1) for a self-driven impactor as a percussive displacement soil boring device with a first and second drilling head section (4, 5), wherein the first drilling head section (4) has out-feed channels (6) and the second drilling head section (5) has a cross-section increasing in the longitudinal direction, characterised in that the second drilling head section (5) has a plurality of step-shape designed areas (7, 8), which are arranged behind an out-feed channel (6) viewed in the longitudinal direction and have a step height (H1, H2) which is smaller than a third of the width of an out-feed channel (6), wherein the first drilling head section (4) is arranged in the advance direction of the soil boring device before the second drilling head section (5).

2. Drilling head (1) according to Claim 1, characterised in that the step-shaped areas (7, 8) are designed without cutting edges in the circumferential direction and / or radial direction (R).

3. Drilling head (1) according to Claim 1 or 2, characterised in that two step-shaped areas (7, 8) are present.

4. Drilling head (1) according to Claim 3, characterised in that the step-shaped areas (7, 8) essentially have the same step height (H1, H2).

5. Drilling head (1) according to one of Claims 1 to 4, characterised in that at least four, preferably six, projections (9) are provided, which form four or six out-feed channels (6).

6. Drilling head (1) according to one of Claims 1 to 5, characterised in that at least one of the projections (9) bounding an out-feed channel (6) projects above the diameter of the second drilling head section (5).

7. Soil boring device, which is designed as a self-driven impactor, which works to displace soil, having a drilling head (1) according to one of Claims 1 to 6 and a housing, characterised in that a) between the step-shaped areas (7, 8) at least one step height (H1, H2) is present, of a size that, in relation to the housing of the soil boring device, is at least 4%, b) at least one of the step-shaped areas (7, 8) has a step length (SL1, SL2) of a size that, in relation to the housing of the soil boring device, is at least 5% and / or c) the last step-shaped area (8), spaced apart from the exposed end of the drilling head (1), projects above the diameter of the housing of the soil boring device.