EP0862678A1

EP0862678A1 - Drill bit

Info

Publication number: EP0862678A1
Application number: EP96939744A
Authority: EP
Inventors: Josef Mocivnik
Original assignee: Techmo Entwicklungs und Vertriebs GmbH
Current assignee: Alwag Tunnelausbau GmbH
Priority date: 1995-11-23
Filing date: 1996-11-22
Publication date: 1998-09-09
Anticipated expiration: 2016-11-22
Also published as: CZ290060B6; AT1513U1; DE59604134D1; AU7684996A; GR3033073T3; PL180429B1; PT862678E; WO1997019247A1; CZ155998A3; PL326764A1; EP0862678B1; ATE188535T1; ES2143244T3

Abstract

Described is a drill bit (1), in particulare a bit for a percussion or rotary-percussion drill, the tip of the bit having cutting edges (3, 4) designed to detach and/or break up the material to be removed, at least one cutting edge (4) running in a curve radially across the face (2) of the bit. The invention calls for at least one additional, straight, cutting edge (3) located on the convex side of the curved cutting edge (4).

Description

B O H R K R O N E

The present invention relates to a drill bit, in particular percussion or rotary percussion drill bit, the drill head of which has cutters on its end face for loosening and / or crushing the material to be mined, at least one cutting edge being curved in a radial direction of the end face of the drill head.

Drill bits, in particular for percussion or rotary percussion drilling, have become known in various embodiments. DE-A 28 41 679, DE-A 29 52 295, DE-A 30 25 890 or DE-A 38 20 695 can be found for rock drill bits for rotary impact drilling, with a plurality of radial ones on the end face of the drill head Cutting edges running in the direction of the end face are arranged, some of which extend only over part of the radial extent of the end face. When rotary percussion drilling conventional ^¬ is in each case after a beating stress on the drilling this drill bit may crown by a certain angle displaced and in turn acted upon by an impact tool, where by the alternate displacement in the rotational direction and hitting systematically on the path swept by the drill bit during the rotary movement area, the Material is crushed and broken out. The cutting edges used in the known embodiments are essentially trapezoidal or triangular-shaped and thus, in the event of striking stress, cause grooves or grooves to be formed by the cutting edges penetrating into the material to be broken down, with those extending in the radial direction being arranged Cutting through the striking stress the material is divided into sectors when penetrating the cutting. In the event that the mutual angular distance is chosen too large in the case of the rotary movement between the impact loads, only grooves are worked into the material by the cutting edges and relatively large, sector-shaped, raised material cross-sections remain between the individual grooves. cuts that cannot be easily broken out. For proper dismantling, care must therefore be taken to ensure that the angle of rotation selected between the impact stresses is dimensioned sufficiently small to be able to effect the spreading of the sector-shaped, rib-like elevations of the material as completely as possible by renewed displacement and penetration of the cutting edges. In addition, it is immediately apparent that this angular distance is essentially determined by the distance on the outer circumference of the drill bit in the case of a radial arrangement of the cutting edges, while at the same time an unnecessarily tight setting of the cutting edges is carried out in the direction of the center. Furthermore, especially with hard rock, there is a fear that in the event that the sector-shaped elevations between the penetration points of the cutting edges cannot be easily broken away by the penetration of the cutting edges when the cutting edges are penetrated, the entire rotation of the drill bit will be completed or with a correspondingly smaller angular spacing, if the cutting edges are arranged symmetrically, the cutting edges enter or slip into already existing notches or grooves and the material cross section existing between individual grooves running in the radial direction cannot be reduced.

Similar designs of a drill bit or a drill bit can also be found in EP-A-0 017 518, where specially designed cutting edges which are partially detachable in corresponding recesses in a drill head also run essentially in the radial direction, which in turn results in the above-mentioned problems .

Furthermore, DE-C 918 741, for example, shows a rock drill with single or multiple cutting edges, at least one arcuate cutting edge being provided in order to even out the wear of the cutting edges over their entire extent. Furthermore, it is proposed to provide an additional straight cutting edge in the concave region of the arcuate cutting edge, if necessary, in order to prevent the formation of the cutting edge Avoid cutting painted areas. According to this state of the art, however, to prevent excessive wear on the edges of the drill bit, additional Aufpanze¬ rungen must be provided, such excessive wear in particular due to the curved shape of the cutting edges, uneven weight distribution and unbalance of the entire drill bit and the resulting Problems in achieving a straight borehole will cause.

The present invention now aims to further develop a drill bit of the type mentioned at the outset in such a way that a correspondingly modified positioning of the cutting edges on the end face of the drill head of the drill bit can achieve a more rapid breakdown of the cutting edge. In particular, the aim is to ensure that even if a relatively large angular distance between individual impact stresses in a rotary impact drill is selected, the entire area to be removed is covered substantially uniformly by the cutting edges and the material cross sections remaining between individual penetration points of the cutting edges are secure can be degraded when passing over a nachfol ^¬ constricting cutting or broken. To achieve this object, the drill bit according to the invention is essentially characterized in that at least one further rectilinear cutting edge is arranged on the side of the convex curvature of the curved cutting edge. Since, according to the invention, in addition to a curved cutting edge according to the invention, a further rectilinear cutting edge is arranged on its convexly curved side, it is ensured that, in contrast to the use of cutting edges arranged only in the radial direction, which form a stop pattern with the formation of sector-shaped elevations between the individual penetration points of the cutting edges show that a less uniform and less regular stop pattern can be generated, the individual penetration points or lines of impact in the stop pattern of the cutting edges being cross different angles. As a result, when the material cross-section to be mined is swept by rotating the drill bit, a stop pattern is obtained in which at least partially irregularly shaped elevations remain between individual stop lines of the cutting edges, which can be easily broken due to their irregular shape. Because the straight cutting edge is arranged on the side of the convex curvature of the curved cutting edge, a more uniform weight distribution is achieved over the entire cross section of the drill bit, so that overall an unbalance of the drill bit which impairs the achievement of a straight bore is achieved in a simple manner and uneven wear can be avoided. In this context, it is also particularly preferred that the common center of gravity of the cutting edges lies in the longitudinal axis of the drill bit.

In order to equalize the load on the drill bit and in particular its end face and the cutting edges arranged thereon, it is proposed according to a further preferred embodiment that the surfaces enclosed by two adjacent cutting edges on the end face of the drill bit are essentially the same size, which also means that Attack pattern can be improved even with larger angular distances between the striking stresses and thus an overall increase in propulsive power can be achieved.

For a structurally particularly favorable production it is further provided that the curved cutting edge is formed by a circular arc, an ellipse or parabola, as corresponds to a further preferred embodiment of the invention.

As indicated above, the curvature of the at least one cutting edge curved to the radial direction of the end face can be designed as an arcuate curvature or generally as a conic section line, this making it possible to produce the cutting edge relatively easily. Hiebei can the curvature can be selected within wide limits according to the conditions of use, very flat curvatures, ie large radii of curvature, which result in cutting edges which differ only slightly from cutting edges aligned in a straight line, are also possible. Of course, cutting edges can also be used whose curvature has at least one turning point. The number of cutting edges arranged on the drilling head also essentially depends on the intended use, ie on the material to be dismantled, and on the size of the drilling head. While with relatively small diameters of the drill head with relatively few cutting edges, ie for example two to four cutting edges, at least one of which is curved to a radial direction of the end face of the drilling head and another on the side of the convex curvature, the length can be found , The number of cutting edges in the case of larger diameter drilling heads, for example having a diameter of up to 80 or 100 cm, can be a multiple of the number of cutting edges specified above, for example up to 40 or 50 cutting edges.

According to a particularly preferred embodiment, the drill bit according to the invention is developed in such a way that the straight cutting edge forms an angle with a radial direction of the end face. By providing a straight cutting edge enclosing an angle with a radial direction, in particular in combination with the curved or curved cutting edge, the desired, non-uniform cut is in any case essentially independent of the positioning of the straight-running cutting edge - field pattern ensured.

According to a further preferred embodiment, it is provided according to the invention that the rectilinear cutting edge is designed as a cutting edge which extends in the radial direction and extends from the center of the drill bit to the edge of the end face of the drill bit. By providing such a radially and completely The actual radius of the cutting edge extending towards the end face ensures that, together with the at least one cutting edge which is curved to the radial direction, essentially diamond-shaped elevations are formed between adjacent stop lines, with such diamond-shaped, remaining material cross sections between the one individual stop lines at the latest with a renewed rotation ensures that a cutting edge essentially hits a remaining, diamond-shaped cross section in the middle and that this remaining material cross section is therefore reliably and completely eliminated.

In order to enable safe and complete machining of the material cross section, in particular in the middle area and at the same time in the edge areas lying on the outer circumference, it is provided according to a further preferred embodiment that the curved cutting edge starts from the center of the drill bit or through the center the drill bit runs. Such a configuration ensures that the material cross sections remaining on the outer circumference of the drill bit between the individual stop lines are also small, and thus a complete breakout of the material can be ensured.

For a further improved sweeping of the areas lying on the outer circumference, the embodiment is also preferably made such that the end of the cutting edge, which lies at an angle with the radial direction, and / or the curved cutting edge, with a radial face, lies at the outer edge of the drill bit encloses an angle between 10 and 40 °, in particular 15 to 30 °.

For a correspondingly simple penetration of the cutting edges into the material and to simplify loosening and breaking out of the material remaining between the stop grooves produced by the cutting edges, the design is further preferably made such that the cutting edges in cross-section essentially are triangular in shape and are provided at their tips with cutting edges formed, for example, by hard material inserts.

In order to enable easy removal of larger material parts, the design is preferably such that the drill head has offset and / or flattened peripheral areas on its outer circumference in addition to the cutting edges, which may have additional cutting edges in the direction of rotation of the drill bit are provided. Furthermore, such additional cutters arranged in the direction of the drill bit also ensure that a correspondingly uniform outer contour of the borehole to be produced can be achieved.

For a simple introduction of a rinsing or cooling liquid into the area of the end face of the drill bit and / or also for a simple removal, in particular rinsing out, of the removed material, it is preferably provided according to a further embodiment that the drill bit has at least one channel for the introduction of a Flushing or cooling liquid and / or designed to discharge the degraded material. For a uniform distribution over the entire end face of the drill bit, it is preferably provided that the channel opens into a plurality of outlet openings, which on the end face of the drill head are distributed symmetrically between the cutting edges.

For processing particularly hard or resistant materials, provision can also be made for additional pin-shaped or spherical hard material inserts to be fixed to the end face of the drill bit, in order to remove larger material cross-sections as completely as possible, particularly in the peripheral regions located on the outer circumference. This also allows the weight distribution of the drill bit to be evened out in order to achieve a straight bore. The invention is explained in more detail below on the basis of an exemplary embodiment shown in more detail in the accompanying drawing. In this show

Figure 1 is a schematic side view, partly in section, of a drill bit according to the invention.

FIG. 2 shows a plan view of the end face of the drill head of the drill bit according to arrow II of FIG. 1;

3 shows a stop diagram which is obtained with the sheath arrangement shown in FIG. 2; and FIGS. 4 and 5, in views similar to FIG. 2, on a reduced scale, schematic representations of further modified embodiments of the arrangement of cutting edges on a drill head of a drill bit according to the invention.

In Fig. 1, 1 generally denotes a drill bit, on the end face 2 of the drill head, a plurality of cutting edges

3 and 4 is arranged, as can be seen in more detail from the top view of FIG. 2. In the embodiment shown, one cutting edge 3 runs in a straight line and in the radial direction of the end face 2 of the drilling head, while the other cutting edge

4 runs in a circular arc shape relative to the radial direction. Both of the cutting edges 3 and 4 of this embodiment shown start from the center 5 of the drill bit 1, furthermore both cutting edges 3 and 4 extend to the outer circumferential edge of the end face 2 of the drilling head. The ends of the cutting edge 4 lying on the outer circumference enclose an acute angle with a radial, which is schematically denoted by α.

As can be seen in particular from the schematic representation according to FIG. 1, a channel 6 is provided in the interior of the drill bit, which channel opens into a plurality of outlet openings 7 on the end face 2, with flushing or cooling liquid being able to be discharged through these outlet openings 7. Furthermore, a plurality of stepped or stepped areas 8 are provided between the cutting edges 3 and 4, which facilitate material removal of possibly larger material. enable pieces. Furthermore, cutters 9 can also be provided on these stepped or stepped areas 8 in the direction of rotation, which can also be used for a correspondingly smooth formation of the outer contours of the borehole to be produced. If necessary, additional dismantling tools, which are indicated schematically in FIG. 2 by 10, can also be provided on the end face 2 of the drill bit.

With the in Fig ^' . 2, the arrangement of the cutting edges 3 and 4 can be realized, for example, the stop diagram shown in FIG. 3, one of the positions of the cutting edges 3 and 4 being indicated by strong lines and the achievable impact lines or respectively corresponding lines being correspondingly weaker Cutting lines of the cutting edges 3 and 4 are indicated after twisting. It results directly that the cutting edges 3 and 4 are arranged differently in the radial direction on the end face 2, one of the cutting edges 4 being curved and the straight cutting edge 3 being arranged on the side of the convex curvature of the curved cutting edge 4 is to achieve a stop image in which essentially diamond-shaped material cross sections remain between the individual lines. By appropriate choice of the angle depending on the relative positioning of the cutting edges 3 and 4 and depending on the curvature of the cutting edge 4, the angle between adjacent impact stresses can be chosen such that one of the cutting edges 3 and 4 at the next rotation in essentially meets the remaining material cross-sections in the center and thus a safe breakout of the material over the entire surface can be guaranteed. It is immediately apparent that the proposed arrangement of the cutting edges in particular prevents the cutting edges 3 and 4 from re-inserting or slipping into existing depressions or indentations from previous impact stresses, but rather from reliably removing them between ahead outgoing penetration of the cutting remaining material can be made.

From Fig. 3 it can also be seen that the proposed mutual arrangement of the cutting edges 3 and 4, both inside the surface to be dismantled and on the outer circumference, means that no excessively large material cross-sections to be dismantled remain between individual stop lines, and that therefore also hard rock without being able to dismantle safely, without having to work with excessively small angular distances between the individual impact loads.

Furthermore, in order to avoid uneven stresses and to achieve a straight borehole, the center of gravity of the cutting edges 3 and 4 lies essentially in the center point or the longitudinal axis of the drill bit 1, which is denoted by 5. The weight distribution can further be favored by, for example, symmetrically arranged channels 7 and by corresponding designs of the flattened areas 8 and also any additional hard material inserts 10 that may be required. For a uniform and favorable field pattern, it is also provided that surface areas of the end face 2 of the boring head 1 enclosed between two adjacent cutting edges or sections of cutting edges 3, 4 are essentially of the same size in order to further promote the degradation performance.

4 and 5 show further schematic views of modified embodiments of the arrangement of cutting edges on each end face 2 of a drill head. Thus, the embodiment shown in FIG. 4 has a curved cutting edge 11 in the form of a parabola, a straight cutting edge 12 again being provided on the side of the convex curvature. By appropriate choice of both the curvature behavior of the arcuate cutting edge 11 and the relative positioning of the cutting edges 11 and 12 between adjacent cutting edges or sections of cutting edges 11 and 12 again have essentially the same surface areas on the end face 2 and again the center of gravity is centered in the area of the center point or the longitudinal axis 5 of the drill bit 1.

In the further modified embodiment according to FIG. 5, an arcuate cutting edge 13 is defined by a section of an ellipse, in addition two rectilinear cutting edges 14 enclosing an angle are arranged on the side of the convex curvature of the arcuate cutting edge 13, again care is taken to ensure that the surfaces are distributed as evenly as possible between adjacent cutting edges or cutting portions 13 and 14 and that the center of gravity is centered as completely as possible.

It is essential for all of the embodiments that, because the different cutting edges are arranged to run differently in the radial direction on the end face 2, at least one of the cutting edges 4, 11 and 13 being curved, a stop image can be obtained in which different patterns or material cross sections remain between the individual stop lines. Furthermore, by appropriate choice of the angle of rotation of the drill bit 1 between adjacent impact stresses, it is ensured that at least one of the cutting edges hits the remaining material cross sections essentially centrally in the next rotation, and thus a safe breaking out of the material over the entire surface can be achieved. In this way, by providing different curvatures or by providing straight cutting edges which enclose an angle with a radial direction, it is always ensured that when the cutting edges are reattached they do not enter or slip into existing recesses or indentations of remaining material cross sections can.

Claims

Patent claims

1. drill bit, in particular percussion or rotary impact drill bit, the drill head on its end face (2) cutting (3, 4, 11,

12, 13, 14) for loosening and / or crushing the material to be mined, at least one cutting edge (4, 11, 13) being curved toward a radial direction of the end face (2) of the drill head, characterized in that at least one further is rectilinear extending cutting edge {3, 12, 14) is arranged on the side of the convex curvature of the curved cutting edge (4, 11, 13).

2. Drill bit according to claim 1, characterized in that the common center of gravity of the cutting edges (3, 4, 11, 12, 13, 14) lies in the longitudinal axis (5) of the drill bit (1).

3. Drill bit according to claim 1 or 2, characterized in that the surfaces enclosed by two adjacent cutting edges (3, 4, 11, 12, 13, 14) on the end face (2) of the drill bit (1) are essentially of the same size .

4. Drill bit according to claim 1, 2 or 3, characterized gekennzeich¬ net that the curved cutting edge (4, 11, 13) is formed by an arc, an ellipse or parabola.

5. Drill bit according to one of claims 1 to 4, characterized in that the rectilinear cutting edge (14) includes an angle with a radial direction of the end face (2).

6. drill bit according to one of claims 1 biε 5, characterized ge ^¬ indicates that the curved cutting edge (4, ll, 13) from the center (5) of the drill bit (1) goes out or through the center (5) of the drill bit (1 ) runs.

7. Drill bit according to one of claims 1 to 6, characterized ge indicates that the rectilinear cutting edge (3, 12) is formed as a cutting edge (3, 12) extending in the radial direction, which is from the center (5) of the drilling bit (1) to the edge of the end face (2) of the drill bit (1).

8. Drill bit according to one of claims 1 to 7, characterized in that the end lying on the outer edge of the drill bit (l) lies the straight edge and / or the curved edge (3, 4, 11, 12, 13, 14) encloses an angle (α) between 10 and 40 °, in particular 15 to 30 °, with a radial face.

9. Drill bit according to one of claims 1 to 8, characterized in that the cutting edges (3, 4, 11, 12, 13, 14) are essentially triangular in cross section and have ge at their tips with, for example, hard material inserts ¬ formed cutting edges are provided.

10. Drill bit according to one of claims 1 to 9, characterized in that the drill head (1) has on its outer circumference next to the cutting edges (3, 4) stepped and / or flattened circumferential areas (8), which optionally in the direction of rotation the drill bit (1) is provided with additional cutting edges (9).

11. Drill bit according to one of claims 1 to 10, characterized in that the drill bit (1) with at least one channel

(6) is designed to introduce a rinsing or cooling liquid and / or to remove the degraded material.

12. Drill bit according to claim 11, characterized in that the channel (6) mün¬ det in a plurality of outlet openings (7), which on the end face (2) of the drill head (1) symmetrically distributed between the cutting edges (3, 4, 11, 12, 13, 14) open.

13. Drill bit according to one of claims 1 to 12, characterized in that additional pin-shaped or spherical hard material inserts (10) are fixed on the end face (2) of the drill bit (1).