EP0843072B1 - Drill tip for soil drilling apparatus - Google Patents

Description

The invention relates to a drill tip for Earth drilling devices in the preamble of the main claim Art. Such a drill tip is from NL 88 02005 known. NL 88 02005 relates to a method and an apparatus for Performing earth drilling. From this publication, one is pure cone-shaped drill head known, provided with a number spirally around the surface of outwardly extending ribs extending to the tip, which have a cutting and transporting function. A comparable drill tip is from European patent 0 429 130 known.

The drill tip known from EP-B-429.130 comprises a lateral surface which is spirally executed, has a pure in a first longitudinal section triangular shape and in a second longitudinal section, perpendicular to the first cross section an approximately triangular shape, the base of the corresponds to the maximum width of the relevant cross-section and the sides have a concave shape. That means that this is known Drill tip in said second longitudinal section, in the direction of Seen tip, tapered (Fig. 2A). The sides of this cross section lie therefore within the side of a circumscribing triangle, determined by said base and two sides that are in the free end of the drill tip meet. The edges of the spiral surface serve for Use as reasonably cutting sides. This well-known The drill tip is made of aluminum.

With a drill tip of the type mentioned, which is usually also "lost tip" means relatively deep holes in the ground drilled, e.g. for seismological investigations. after the Has been drilled deep enough into the ground Drill tip detached from the drill pipes. An explosive charge can be Drill pipes are thrown into the drilled hole, on the remaining one Drill bit. Then the drill pipes are removed and will detonated the explosive charge, causing vibrations in the Distance from the drilled hole can be recorded. Such can also Holes for other types of examinations or for inserting e.g. Basic components and the like can be used.

Especially when the well-known drill bit in relatively hard Soil is used or when used on relatively hard parts in the Soil, e.g. on stones, gravel, primary rock, hard layers of sand, wood and the like, there are severe deformations of the drill tip, namely the front end and the cutting sides and it is heated up due to friction. In addition, the Simply stick the drill bit, i.e. are blocked in the sense of rotation, whereby the drilled hole does not reach the desired depth while there is also a great risk that the drill tip may be vertical drilling path is moved away. In addition, the Steel drill pipes can be strongly heated when the drill tip and the Drill pipes are rotated without axial displacement occurring. Namely, at the level of couplings between the drill pipes then a large friction between the drill pipes and the environment and therefore a strong heating of the drill pipes can occur. This warmth can are poorly released from the aluminum into the environment. As a result this strong heating of the drill tip and / or the drill pipes Simply damage occurs, becomes a less suitable one Preserved drilling result and exists when used for the named seismological investigation of the risk of spontaneous combustion possibly thrown through the drill pipes into the drilled hole Explosive charge occurs, which can be life-threatening. The continues Danger due to the deformation and heating of the drill tip this does not come off, or at least not completely, from the drill pipes.

US 3,557,887 describes a drill bit for use with Test bores, comprising an essentially conical web provided with a sheet on both sides. The leaves extend in one Spiral shape from a connecting part at the tip to the opposite end of the web. Each sheet has an im Sense of rotation in front, concave part, which in a convex part transforms. Means are provided to secure this drill bit to one To fix the well, which means are designed such that the available dock is used in an optimal way.

This well-known drill bit is not of the "lost-tip" type, but is to be taken up again with the well. That is exactly what they are Means are provided to secure this drill bit to a well Fasten. In addition, the blades of this well-known drill bit cutting and extending to close, even at the top of the footbridge.

The invention therefore aims at a drill tip in the preamble of the main claim described type, the disadvantages mentioned are avoided, while maintaining their advantages. This will be a Drill tip according to the invention by the measures according to the Characteristic part of claim 1 characterized.

A drill bit according to the invention has, due to the shape of the Lateral surface, which is in at least one side view of the drill tip is convex, a somewhat dull one at the front when used Tip in relation to the known drill tip for a borehole same diameter. Surprisingly, it turned out that with this relatively blunt drill tip, particularly good drilling results can be obtained. When drilling, a drill bit follows after Invention of a relatively straight drilling section, even if Irregularities are hit in the ground or when in a relative hard soil is drilled. In addition, almost no deformation occurs or damage to the drill tip, which makes it a particularly good one and regular borehole is maintained. It will also prevents the drill tip from being detached from the drill pipes can. The temperature of the drill tip, as well as the drill pipes, remains When used relatively low, creating the risk of spontaneous combustion any explosive charge occurs, is averted. Therefore one Drilling system, provided with a drill tip according to the invention, with Security used in seismological surveys and the like become. Another advantage of a drill tip according to the invention is in the fact that these can be easily and without risk of damage Impact loads on the drill pipes, e.g. by ramming into the ground can be driven. For example, obstacles such as stones, that are hit by the drill tip, dismembered or at least from the intended path of the drill bit are removed, followed by another Drilling by rotating the drill tip is possible again. The or everyone Groove in the lateral surface ensures suitable removal of a during drilling Part of the material from the borehole for the axial displacement due to the Rotation, and also the longitudinal edges of the or each groove can be one have a somewhat cutting effect. By having the or each groove at a distance from the front end of the drill tip when used starts, this groove or grooves is prevented from the front end can have a cutting effect. This will prevents in a relatively simple manner that the drill tip is consequent such grooves can get stuck in the sense of rotation. Because not with Grooved, front part of the drill tip comes first in contact with the ground and is used to a significant degree for lasting Ensure freedom of rotation of the drill tip. It also continues prevents the drill tip, in particular each defining a groove Surface is damaged when subjected to impact loads. The grooves mostly guide already somewhat churned earth and the like, while the Groove bottom surface of the or each groove also a certain digging, at least earth can have a pushing-away function in the radial direction.

In more detail, a drill tip according to the invention further characterized by the measures according to claim 2.

Such a drill tip, especially if the whole Shell surface is essentially convex, has an even more optimized Effect.

In a closer embodiment, a drill tip according to the Invention further characterized by the measures according to claim 5.

The relatively large change in angle of the bit during Axial displacement offers the advantage that the parts of the Drilling device which, when in use, makes frictional contact with the Make environment relatively quick in comparison to this environment Drilling direction can be shifted. This will cause intense heating the drill tip even stronger due to such friction counteracted, the more than the heat directly to a relatively cool Part of the area can be delivered.

Part of the problems of the known drill bit will also caused or at least increased by the fact that it is known Drill tip is made of aluminum. Aluminum has a relative low hardness and also a relatively low melting temperature and a high heat capacity. When used, therefore, in this known drill tip, especially with the strong heating mentioned the drill tip, there are severe deformations of the aluminum, especially when subjected to shock loads and when touching hard floor parts like stones and the like. As a result of these deformations and Gradually the edges of the edges become damaged spiral surface and thus the drilling ability of this known Remove the drill tip, which further increases the disadvantages mentioned earlier be reinforced.

Another disadvantage of this known drill tip Aluminum is that after drilling the hole in it Whole remains in the ground, even if an explosive charge detonates thereon. Aluminum is relatively bad for the environment, especially at its manufacture, and is relatively scarce.

The invention therefore also aims at a drill tip of the "lost tip" type, the above disadvantages being avoided. This will be a Drill tip according to the invention by the measures according to claim 6 characterized.

The fact that a drill tip according to the invention with a Surface hardness is performed, which is compared to the surface hardness of the Aluminum is relatively high, more particularly a surface hardness of 140 Brinell or more will damage the drill bit in easily prevented even better.

In a particularly advantageous embodiment, a Drill tip according to the invention by the measures according to claim 7 characterized.

The use of an iron-containing alloy such as cast iron or cast steel offers the advantage of being relatively easy to obtain high surface hardness and good heat dissipation when used. In addition, such an alloy is less polluting. Certainly when the drill bit is detonated by an explosive charge at least partially fragmented. Another advantage of such The tip of the drill is that it is relatively heavy. This will make this follow their straight drilling path even better when used. A such drill bit is still relatively cheap.

In an alternative, advantageous embodiment, a Drill tip according to the invention further by the measures Claim 8 marked.

The fact that the rear part of the Drill tip made of plastic, especially of relatively environmentally friendly Plastic, and the front part made of metal, especially one ferrous, relatively hard metal type or alloy is produced, will get a relatively cheap drill tip, which also at Use is heated even less. Because the possible explosive charge on the plastic part of the drill tip will fall, which will remain relatively cool there will be no spontaneous detonation of the explosive charge as a result of the Make contact with the drill tip. The plastic is preferred a biocompatible plastic.

The invention further relates to a drilling device for Use with a drill tip according to the invention, which Drilling device characterized by the measures according to claim 9 becomes.

The invention also relates to a method for Make a hole in the ground using a drill bit after the Invention. Such a method is according to the invention by Measures according to claim 10.

With such a method can be particularly simple and a straight, relatively deep borehole can be obtained relatively inexpensively, in addition, the risk of a possible Explosive charge to be deposited in the hole on the drill tip spontaneously detonates. This method is therefore compared to the known methods relatively fast, cheap and safe.

Further embodiments of a drill tip, one Drilling device and a method according to the invention are in the Subclaims given.

Fig. 1 eine perspektivische Ansicht einer Bohrerspitze nach der Erfindung;

Fig. 2 eine Seitenansicht einer Bohrerspitze nach Fig. 1;

Fig. 2A schematisch eine Seitenansicht einer Bohrerspitze nach der Erfindung mit darin wiedergegebener vergleichbarer Seitenansicht einer Bohrerspitze der bekannten Art für ein Bohrloch mit gleichem Durchmesser;

Fig. 3 eine Vorderansicht einer Bohrerspitze nach Fig. 1;

Fig. 3A schematisch eine Vorderansicht einer Bohrerspitze nach der Erfindung mit darin wiedergegebener vergleichbarer Vorderansicht einer Bohrerspitze der bekannten Art für ein Bohrloch mit gleichem Durchmesser;

Fig. 4 eine Draufsicht einer Bohrerspitze nach Fig. 1;

Fig. 5A und 5B je einen Querschnittsansicht, bzw. über die Linie VA-VA und VB-VB in Fig. 3;

Fig. 6 eine Bohrerspitze nach der Erfindung auf einem Bohrrohr in einer Bohrvorrichtung nach der Erfindung; und

Fig. 7 eine alternative Ausführungsform einer Bohrerspitze nach der Erfindung in teilweise durchgeschnittener Seitenansicht.

To illustrate the invention, an embodiment of a drill tip, a drilling device and a method is described with reference to the drawing. It shows:

Figure 1 is a perspective view of a drill tip according to the invention.

FIG. 2 shows a side view of a drill tip according to FIG. 1;

2A schematically shows a side view of a drill tip according to the invention with a comparable side view of a drill tip of the known type reproduced therein for a borehole with the same diameter;

Fig. 3 is a front view of a drill tip according to Fig. 1;

3A schematically shows a front view of a drill bit according to the invention with a comparable front view of a drill bit of the known type reproduced therein for a borehole with the same diameter;

FIG. 4 is a top view of a drill tip according to FIG. 1;

5A and 5B each a cross-sectional view, or over the line VA-VA and VB-VB in Fig. 3;

6 shows a drill tip according to the invention on a drill pipe in a drilling device according to the invention; and

Fig. 7 shows an alternative embodiment of a drill tip according to the invention in a partially sectioned side view.

In Fig. 1 is a perspective view of a Drill tip 1 shown according to the invention. The drill tip 1 has a relatively broad base 2, a relatively blunt one End 3 and a lateral surface 4, which is somewhat convex is. This means that the outer surface 4 on all sides is somewhat curved outwards and therefore the Drill tip 1 in at least one of the views "more is conical ". Essentially every longitudinal section through the Drill tip 1 determines the outer surface 4, therefore one at least partially convex boundary line B (Fig. 2, 3), the drill tip in a first view (Fig. 2) has a somewhat larger width than in one second view standing thereon at right angles (FIG. 3). The Curvature towards the outside (convexity) of the boundaries in the mentioned two views (Fig. 2, 3) may be the same or how shown in the figures may be somewhat different. The Drill tip 1 is made of a relatively hard metal, especially cast iron. In the outer surface 4 are arranged two grooves 5, which are described in more detail become. 1 clearly shows that the grooves 5 somewhat spiral around the outer surface 4 run and a start 6 at some distance from the end 3 have the drill tip 1 and close to the base 2 of the Continue drill tip 1.

In FIGS. 1A and 2A there is a combination Side view or a front view of a drill tip as known from European patent 0 429 130 and one Drill tip 1 shown according to the invention. It is always the known drill tip (known prior art) hatched.

As is clear from Fig. 1A, the known one Drill tip triangular in this first view (pure conical), while the drill tip 1 according to the present Invention in this first view somewhat outward has curved boundary lines B. By the way, at one Drill tip 1 according to the invention in this first view the boundary lines B are also approximately straight or in be bent in another way. It also clearly shows that the well-known drill tip in this first view has a broader base than the drill tip 1 after Invention.

As is clear from Fig. 2A, the known Drill tip somewhat in this second view internally curved (concave) boundary lines B ', while a Drill tip 1 according to the invention in this second view at least partially convex B boundary lines. The well-known drill tip has therefore in this second view (Fig. 2A) one less conical shape, a drill tip according to the invention a more conical shape.

As can be seen particularly from FIGS. 4, 5A and 5B the drill tip 1 in cross section a somewhat oval Shape. The drill tip 1 therefore has something as a whole flattened cone shape.

When using a drill tip 1 after the Invention with the end 3 at the front by drive with a drilling device 15 to be discussed in more detail (Fig. 6) driven into the ground. The one between the above End part 3 and the beginning 6 of the grooves 5 lying tip part 7 the drill tip 1 has an oval or ellipsoid Cut and a relatively smooth surface (Fig. 5A), whereby this despite the reasonably oval or ellipsoidal (somewhat flattened conical) shape rotates relatively easily around the longitudinal axis into the ground can be pressed, displacing the one in front Earth. This prevents the drill tip 1 from jamming, at least not as a result of the tip part 7. The relatively blunt end 3 of the drill tip 1 also ensures a straight axial movement of the drill tip 1 at their Rotation.

Each groove 5 is essentially one Groove bottom surface 8 determined, which is approximately radially on the Longitudinal axis L of the drill tip, i.e. always approximately at right angles or somewhat inclined to the adjacent lateral surface 4 extends (Fig. 5B). At the level of the groove bottom surface 8 there is therefore a difference in level in the lateral surface 4 on; the distance D1 between the longitudinal axis L and the im Sense of rotation opposite the groove bottom surface 8 at the front lying part of the lateral surface 4 is therefore different, in particular smaller than the distance D2 between the Longitudinal axis L and that in the sense of rotation compared to the Groove bottom surface 8, rear part of the lateral surface 4. When the drill tip 1 rotates about the longitudinal axis L. therefore each groove bottom surface 8 is essentially frontal Surface.

From the base 2 extends in the relative blunt end 3 opposite direction a cylindrical Stump 9, around which in two at a distance from each other arranged ring grooves 10 always included an O-ring 11 is. This stump 9 can be in an open end 12 Drill tube 13 are inserted (Fig. 6), the O-rings 11 ensure closure and frictional containment. In the The lateral surface 4 is two in the stump 9 opposite direction from the base 2, extending diametrically opposite incisions 19 are provided in the cams 14 in a known manner on the drill pipe 13 can be added to a rotation of the To prevent drill tip 1 from drilling tube 13, while the drill pipe 13, however, simply in the axial direction can be pulled out of the drill tip.

One shown schematically in Fig. 6 Drilling device 15 comprises a frame 16 with not shown Guides for the drill pipes 13, a first Drive device 17 for engaging and rotating a Drill tube 13 is provided about its longitudinal axis, within of the guides. The drill pipes 13 can be used for drilling be coupled together so that with relatively short Drill pipes 13 a relatively large drilling depth can be achieved can. Next is the drilling device 15 with a second Drive device 18 provided with the shock loads the drill pipes can be placed in the axial direction, to carry out an axial displacement of the drill tip 1. When using the drill tip 1 over the Drill pipes 13 in the sense of rotation from the first Drive device 17 driven. The grooves take care of this 5 for an axial displacement of the drill tip, in Downward direction. Should there be another Rotation of the drill tip 1 can be prevented or at least not to a further axial displacement lead, e.g. in that the tip 3 on a stone or Wood is pushed, so the second drive device be switched on. This creates a shock load on the Drilled pipes 13 and the drill tip 1 created, whereby the Drill tip 1 rammed into the ground in the axial direction by using the stone or the like for example pushes away and / or destroyed. Then the Drill bit can be screwed further into the ground. The slope of the grooves 5, i.e. the inclination to the longitudinal axis L the drill tip is preferably such that a large one Angle change with axial displacement of the drill tip 1 occurs, e.g. an angle of 90 ° or more than 180 ° with an axial displacement of once the length of the Drill tip 1. This is done in a simple way get a good borehole quickly and safely.

The temperature of the drill tip 1 and the drill pipes 13 remains relatively low due to use low friction and good heat conduction in the Surroundings. The hardness of the drill tip 1, at least that of the front lying tip part 7 is such that deformations and There is little or no damage. The hardness is considerably higher than with normally used aluminum and is e.g. more than 160 Brinell, more especially more than 200 Brinell and preferably more than 250 Brinell. ever harder the less risk of shape changes. The weight the drill tip 1 is relatively high, making the It is even better to follow the drill tip along a straight drill path can.

Incidentally, it is noted that an improvement the known drill tip can be reached if it in a metal as described herein, especially iron or an iron-containing alloy, preferably cast iron or cast steel. The results will be therefore not ideal.

7 shows an alternative embodiment of a Drill tip 20 according to the invention. Same parts are with the same reference numerals.

This drill tip 20 consists of a front Tip part 7 made of metal, in particular Cast iron, and a rear part 21 made of one preferably biocompatible plastic. The parts are with each other over one of the tip part 7 extending cams 22 which engage in the rear part 21 connected. The cam 22 has such a cross section that Rotation of the tip part 7 to the rear part 21 is prevented. The plastic forms an insulation between the tip part 7 and the drill pipe 13, whereby Heating the tip part 7 through the drill pipes 13 and vice versa is prevented. It is also biocompatible Plastic has little environmental impact and is relatively cheap. The Grooves 5 preferably begin near the transition between the tip part 7 and the rear part 21, but they can also e.g. continue in the top part or just in some distance from the tip part to start damage prevent even better.

The invention is in no way based on that in the drawing and the description given exemplary embodiments limited. Many modifications are possible. So one can Drill tip circular cross sections according to the invention have or more or less convex Have lateral surface parts. The free end 3 of the drill tip can be faceted and can be more or less blunt be, while also the lateral surface some curvature may have. The coupling means can be designed differently be, e.g. with a different shape or a different number Cams and cuts. Of course, the Drilling device in various suitable ways be executed.

These and many comparable embodiments of one Drill tip, a drilling device or a method are believed not to limit the scope of the invention exceed.

Claims (10)

1. Drill tip (1, 20) of the "lost tip" type for use with an earth drilling rig (15), having an external surface (4) and coupling means (9, 11, 19) for coupling with the earth drilling rig (US), in which the external surface (4) tapers in the direction away from the coupling means (9, 11, 19) and in which at least one groove (5) is arranged along at least a part of the external surface (4) at least to some degree in a helix and in which the external surface (4) forms an essentially convex boundary (B) of at least one longitudinal section of the drill tip, characterised in that the or each groove (5) begins (16) an axial distance from the free end (3) of the drill tip (1, 20) remote from the coupling means (9, 11, 19) and extends in the direction of the coupling means (9, 11, 19).
2. Drill tip according to claim 1, characterised in that the external surface (4) also forms a convex boundary (B) of a second longitudinal section roughly at right angles to the first longitudinal section, and preferably the entire external surface (4) is essentially convex.
3. Drill tip according to one of the preceding claims, characterised in that the or each groove (5) is essentially determined by a groove bottom surface (8) which, viewed in a cross-section or the drill tip (1, 20), encloses an angle with the neighbouring external surface (4), and the groove (5) defines a difference in level in the external surface (4).
4. Drill tip according to one of the preceding claims, characterised in that the drill tip (1, 20) has at least one pointed flattened conical end (7) with an essentially smooth outer surface.
5. Drill tip according to one of the preceding claims, characterised in that the or each groove (5) and the external surface (4) are embodied in such a way that in use a displacement of the drill tip (1, 20) in the ground over its full length causes a rotation about the longitudinal axis of more than 40°, preferably more than 90°, in particular more than 180°.
6. Drill tip according to one of the preceding claims, characterised in that at least the part (7) of the external surface (4) of the drill tip (1, 20) lying at the front in use has a surface hardness which is higher than the surface hardness of aluminium or aluminium alloys, in particular a surface hardness of more than 160 Brinell and preferably a surface hardness of more than 250 Brinell.
7. Drill tip according to claim 5, characterised in that at least the part (7) of the external surface (4) of the drill tip lying at the front in use is made of iron, in particular cast iron, steel, in particular cast steel or such a ferrous alloy.
8. Drill tip according to one of claims 6 or 7, characterised in that the part (7) of the drill tip (20) lying at the front in use is made of metal and at least the part (22) lying at the rear in use is made of plastic.
9. Drilling rig for use with a drill tip according to one of the preceding claims, characterised in that the drilling rig (15) comprises means (17, 18) for action on a drill pipe, which means (17) are arranged for rotation of the drill pipe about its longitudinal axis (L), which means (18) are also arranged to load the drill pipe axially by percussion or pressure loading, independently of or during the named rotation of the drill pipe.
10. Method for production of a hole in the ground with the aid of a drill tip according to one of the preceding claims and a drilling rig, whereby the drill tip is coupled to a drill pipe with the aid of the coupling means and is screwed into the ground with the aid of the drilling rig, whereby earth and the like are forced away essentially laterally by the part of the drill tip lying at the front, while a part of the earth is carried away upwards by the or each groove, whereby stones and similar hard parts struck by the drill tip during drilling are forced away laterally without deformation of the drill tip, and when the drill tip becomes stuck in the direction of rotation, a linear movement of the drill tip in the longitudinal direction is obtained by applying a percussive load to the drill tip, releasing the drill tip in the direction of rotation.

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