EP3370904A1

EP3370904A1 - Hard metal insert and rock drill

Info

Publication number: EP3370904A1
Application number: EP16790598.3A
Authority: EP
Inventors: Jürgen MIEBACH
Original assignee: Colt & Riss GmbH
Current assignee: Colt & Riss GmbH
Priority date: 2015-11-02
Filing date: 2016-11-02
Publication date: 2018-09-12
Also published as: DE102015118689A1; WO2017076875A1; US20190234150A1

Abstract

The invention relates to a hard metal insert (2) for a rock drill (1), which is designed as a spiral drill operating without percussion, comprising a cylindrical drill head (11) and a working end (13) comprising the hard metal insert (2). The hard metal insert (2) comprises two main cutting edges (22) arranged radially opposite one another with respect to a drilling axis of rotation (d) and at an angle to each other to form a centring tip (21), which can each be assigned a peripheral conveying helix (14). In order to realise a drill hole in an easier and simpler manner and without risk of damage, in a workpiece made of rock, glass or similar, it is proposed that the main cutting edges (22) are formed asymmetrically to one another, wherein at least one of the main cutting edges (22) defines a tip (23) projecting in the drilling direction (b) over the radial course of same in a middle region spaced apart from the radial ends thereof.

Description

Carbide insert and rock drill

The invention relates to a hard metal insert for a rock drill, which is designed for drilling rock, rocky material, hard plastic, glass or the like as a non-impact twist drill with a cylindrical drill body and a carbide insert having the working end, wherein the carbide insert two with respect to a Bohrerdrehachse radially each other

opposite and with the formation of a centering tip has angularly arranged main cutting edges, each associated with a rotating conveyor coil. The invention further relates to a rock drill with the

Carbide insert.

When drilling rocks, rocky material,

Hard plastic, glass or the like without a blow is the problem that, because of the lack of impact, a

Bore very awkward and second consuming introduced. On the other hand, drilling with punch can not

be applied, since such materials are prone to break out and chipping, which is up to the

Destruction of the relevant workpiece may result.

For example, in a glazed wall tile of rock-like composite material, its front hard and brittle glaze must first be softened and then softer

Carrier body of the wall tile to be pierced, which requires a large experience of the boring.

An object of the invention is a generic

Carbide insert or a rock drill with this

To provide carbide insert, by means of which a

Bore faster, easier and easier, and in terms of damage in a workpiece made of rock, rock-like material, hard plastic, glass or the like can be introduced.

The stated object is achieved by the

Characteristics of claim 1 solved. advantageous

Further developments are described in the subclaims. The stated object is already achieved in that the main cutting edges are formed asymmetrically to each other, wherein at least one of the main cutting defined over its radial course in a spaced-apart from their radial ends central region in the drilling direction a projecting tip for triggering a transverse movement.

The asymmetry thus manifests itself in that the at least one main cutting edge has the projecting in the drilling direction tip. As a result of this asymmetry, the cutting behavior of the two main cutting edges is different. When drilling is through the projecting in the direction of the top of the

Rock drills exerted a transverse force through which the

Rock drill is pushed away mainly radially and thus forced into a transverse movement. The rock drill may be pushed away from the tip and toward the other major cutting edge. As a result, the other main cutting edge is correspondingly stronger against the

Drilled bottom pressed, which in turn has a radial

Back pressure and thus supports or triggers countermovement to the pushing away of the rock drill. When drilling with impact a striking motion is exerted in the direction of drilling on the bottom of the hole, which makes this very strong

is charged. The one triggered by the tip

Transverse movement, however, acts transversely to the drilling direction and thus much gentler on the workpiece than drilling with impact, so that even in sensitive brittle materials such as tiles and glass drilling quickly and gently

can be introduced.

In particular, the rock drill gets into a

Drilling direction oscillating transverse movement. The transverse movement can also be called tumbling. As a result of

simultaneous rotation of the rock drill, the transverse movement of the working end sweeps over the entire cross-sectional area of the bottom of the hole and thus leads, depending on the

drilling material, to a lighter and more effective

Crushing by scraping, gumming, crushing, crushing or the like of the material at the bottom of the hole. As a result of this transverse movement, the material is released at the bottom of the well, without the need to build a drilling pressure at the bottom of the well, where there is a risk of destroying the well

limiting material. According to our own experiments, the material is stronger by the hard metal insert according to the invention or by the rock drill with this carbide insert than in comparable generic

Crushed rock drilling, so that this material can be easily discharged against drilling direction. Furthermore, the tip generally represents a discontinuity of the main cutting edge over its radial course, at which point the continuous cut interrupted and thus a break is generated to the radially adjoining material. Thus, the material at the bottom of the drilling with its removal becomes stronger

crushed and can thus be transported away easier against drilling direction of the drill tip.

The at least one main cutting edge can be exactly one in

Drill direction protruding tip have. she can

in particular, only have this one peak. In particular, the tip can with its lateral flanks over the entire radial extent of at least one

Main cutting edge. The tip may have a free end with an end point. The end point is arranged with respect to the drill rotation axis at a certain radius.

The main cutting edges may be arranged radially opposite each other. They can be centrally roofed below

Formation of the centering converge. This tip can be rounded at the ends. It can be designed as a projection. Regarding reduced

Frictional losses and thus heating at the bottom of the hole is proposed that the tip even radially right and left of the same results from a steady shape of the at least one main cutting edge. The tip itself may end a discontinuity in the shape of the

represent at least one main cutting edge.

In particular, the entire main cutting edge forms this one point. The tip can extend over the entire or nearly entire main cutting edge and end at a certain radius with its free end in an end point. Preferably, the entire main cutting edge is divided into two sections, forming the tip

roof gable are arranged to each other employed.

In particular, the main cutting edge converges from its two radial ends to the tip. Constructively advantageous simply can be provided that the tip of the at least one main cutting edge is defined radially inwardly and radially outwardly in each case by an unbending or by a concave freewheeling surface. Although a defined by unconstrained freewheeling tip may be more stable against wear and / or against

Damage as a defined by unconfined freewheeling tip but at the same time as less cutting or less effective to produce the

be estimated oscillating pendulum motion. Thus, the carbide insert and thus the rock drill with the carbide insert on the formation of the tip can be adapted to certain materials to be drilled.

It can the cutting edge of the main cutting edge through the associated freewheeling surfaces and the associated against

Drilling direction sloping body surfaces of

Carbide insert the cutting edge of the main cutting edge be formed. Preferably is through this

Freewheeling surfaces with the sloping towards drilling direction

Body surfaces of the carbide insert the entire

Cutting edge of at least one main cutting edge defined. In an advantageous embodiment of the cemented carbide insert, the tip of the at least one main cutting edge is defined radially inwardly and radially outwardly by an unbending or by a concavely curved freewheeling surface.

The profile of the cutting edge of the at least one

Main cutting edge can with respect to a drilling direction

having radial-axial plane at non-curved

Freewheel surfaces have two coincident in the top straight lines or curved freewheeling surfaces have two converging concave arches in the top. At a

Plate-like design of the cemented carbide insert with a height direction extending in the drilling direction and, each arranged perpendicular to each other, with a thickness direction and width direction, this radial-axial plane is arranged perpendicular to the thickness direction. The tip of the at least one main cutting edge may alternatively be formed radially inwardly by an uncurved freewheeling surface and radially outward by a concave freewheeling surface or, conversely, radially inwardly by a curved freewheeling surface and radially outwardly by a concave, non-curved freewheeling surface. The curved freewheeling surface may define part of a semi-cylindrical or part-cylindrical space.

As is common practice, the freewheel surfaces of the

Main cutting radially centered to form a

Border cross-edge to each other. Preferably, the axis of rotation cuts the chisel edge.

The relative radial position of the tip over the at least one main cutting edge can have a decisive influence on the exercise oscillatory transverse movement. The farther the tip is located away from the axis of rotation of the drill, the greater the radial momentum of the lateral force produced by the tip, and thus the effect of the dew

oscillating transverse movement.

In particular, the tip may divide the main cutting edge into two radial sections, i. a radially outer portion and a radially inner portion, share. The ratio of the lengths of the outer portion to the inner portion may be 1 1, preferably 2 2 or 4 4. The bigger that

Ratio is, the farther the tip is radially outward and the greater the expected lateral force.

In another development of the cemented carbide insert, it can be provided that the centering tip is preferably sharpened axially symmetrically with respect to the axis of rotation. It can per radial cutting a main inside to the

associated main cutting drilling rotational direction leading and in particular at an angle less than 60 °, preferably less than 30 ° to the radial direction of the zughörigen

Main divide one to or into the associated one

Conveying spiral extending into it groove-like first

Be provided recess. This can be incorporated in the main cutting edge. With this two-sided tapering into the centering tip, the main cutting edge cutting action can be extended into the centering.

Furthermore, alone or in addition radially outside, each leading to the main cutting Bohrdrehrichtung arranged and in particular at an angle less than 60 ° to the radial direction of the zughörigen main scabbard, a in the

associated conveyor spiral towards extending groove-like second recess be introduced into the drill body.

Thus, the cutting edge can each form a boundary of the first and / or the second recess. She is with and designed by introducing the respective recess.

The recesses may each be assigned from the associated main cutting edge to that of this main cutting edge

Extend the delivery spiral and eventually open there. Thus they allow an improved drainage of

Drilling abraded material against drilling direction in the form of flour, semolina and / or particles. The recesses may each be concave. They can each define a part of a semi-cylindrical space. Furthermore, the two recesses of a main cutting edge can each form an area of this main cutting edge and form a discontinuity in the radial course of the

Main cutting edge radially adjacent to each other. These

Discontinuity, as described above in the context of the tip, cause a breakage of the cuttings, which can be crushed and thus easily transported away.

In this sense, the discontinuity formed by the contiguous recesses may be located at a radial point of the main cutting edge which is different from the free end point of the tip of this main cutting edge. In particular, it may be provided that the discontinuity formed by the adjoining recesses of the main cutting edge radially inward to the top of this

Main cutting edge is arranged. This discontinuity formed by the adjacent recesses of the

Main cutting edge may be a circumferentially facing tip that does not protrude in the drilling direction.

The groove-like first recess can radially over the

Be arranged center axis of the carbide insert out running. This may form a radially inner region of the associated main cutting edge and a radially inner region of the freewheeling edge associated with the other main cutting edge. In particular, the first recess and / or second recess may be arranged in the direction of drilling towards the drill rotational axis at an angle of attack. The

Recesses can be arranged inclined to each other in the drilling direction to the drill axis of rotation.

With the provision of the first recess can thus the

Geometry of the centering point are also decisively changed in that, depending on the depth of the first recess, the above-described transverse cutting edge, which in itself can only be awarded a scraping cutting action, in favor of the extension of the main cutting edge,

can be reduced. It is, however, because of a

Stability and stability of the centering tip as

Considered advantage to obtain the cross-cutting edge and thus the thickness of the centering tip to a small extent. Advantageously, the length of the transverse cutting edge can amount to a few or up to three or up to six centimeters. It can be up to 5% or 3% of the diameter of the masonry drill bit.

The centering of the centering can also

Transverse movement influence, because the larger the

Centering, the lower can be a centering of the centering and the stronger the centering counteracting possible transverse movement of the rock drill during drilling. In particular, it can be provided that the centering point has a centering angle, which for

For example, drilling of glass is preferably 50 ° to 70 °, for drilling, for example, wall tiles 70 ° to 80 ° or for drilling, for example, floor tiles, thermosets and hard composites 110 ° to 140 °. In a further development of the carbide insert both main cutting edges can each projecting in the direction of drilling

Have tip. To obtain an asymmetric effect and thus generation of the transverse movement, it is advantageous that the tip of the one main cutting edge on a first Radius is arranged, which is not equal to a second radius of the tip of the other main cutting edge. In particular, it can be provided that the first radius is greater than the second radius by up to 90%, preferably by up to 60% and in particular by up to 30%. Own attempts to do this give the tendency that with increasing difference of these two radii an increasing erosion can be observed. It is advantageous, the tip of a main cutting edge on the radially inner half of the main cutting edge and the other major cutting edge on the radially outer half of the other main cutting edge are arranged.

The cemented carbide insert can advantageously be formed simply plate-shaped. It can be sintered in its basic form as a blank and then brought to its desired geometries by post-processing.

In particular, the cemented carbide insert on the side with the main cutting edge can be adapted so that it can be inserted in the installation position without transition, i. without the flow

abzutransportierender particle inhibiting projections, heels or the like, merges in the intended conveying direction in the associated conveyor spiral. For this purpose, in addition to the recesses described above in the drilling direction trailing to the same an additional levy

be provided that erodes the cemented carbide insert underside so far that the excavation merges seamlessly into the conveyor spiral.

The present invention is described below with reference to several embodiments of the illustrated in a drawing

Carbide insert or the rock drill with

Carbide insert explained in more detail, but without limiting the invention thereto. In the drawing show:

1 and la a side view of a rock drill with a carbide insert according to FIG. 3 or a Sectional enlargement Ia according to FIG. 1,

2 and 2a another side view of the

Rock drill according to Figure 1 or a

Sectional enlargement IIa according to FIG. 2,

FIG. 3a to 3h each show a view of the carbide insert shown in FIGS. 1 and 2,

4a to 4d each show a view of another

Embodiment of the cemented carbide insert,

5a to 5c each show a view of another

Embodiment of the cemented carbide insert,

Figs. 6a and 6b is a view of another embodiment of the cemented carbide insert or a Ausschnittsvergrö ^¬ fication thereto,

Fig. 6c and 6a is a view of another embodiment of the cemented carbide insert or a Ausschnittsvergrö ^¬ fication thereto,

7a to 7e each show a view of another

Embodiment of the cemented carbide insert and

8a to 8e each show a view of another

Embodiment of the cemented carbide insert.

FIGS. 1 and 2 each show a side view of a rock drill 1 used for drilling rock, rock material, hard plastic, glass or stone

the like is designed as a non-impact twist drill with a cylindrical drill body 11 and a receptacle 12 having working end 13, wherein in the receptacle 12, a plate-shaped cemented carbide insert 2 according to the embodiments shown in Figures 4a - 4e

is soldered. In FIGS. 3 and 5-8, further embodiments of the cemented carbide insert 2 are described in different Views and partly with associated

Cutouts shown.

As the figure 1 and Figure 2 associated

Cut-out enlargement in Figure la and 2a and in the other figures 3-8 removed, the carbide insert 2 with respect to a drill rotational axis d radially to each other

opposite and forming a center point

21 angularly arranged to each other main cutting edges 22. Each main cutting edge 22 is associated with a conveying spiral 14 through which the cut material not cut off by the cemented carbide insert 22 is transported away against the drilling direction b. (In the figures, with larger curved side surfaces, additional lines with a lower line thickness are entered, which do not mark a contour but a depth profile of these side surfaces.)

The main cutting edges 22 are formed in all embodiments of the cemented carbide insert 22 asymmetrically to each other, wherein at least one of the main cutting edges 22 over their radial course in one of its radial ends

spaced middle region defines a tip 23 projecting in the drilling direction b. The tip 23 represents a discontinuity in the radial course of the main cutting edges 22. In all embodiments, if provided, a single projecting tip 23 is arranged in the main cutting edge 22. By projecting in the direction of drilling b tip 23, as described above, when drilling a transverse force generated, the rock drill to a vertical with respect to the drilling direction b oscillating and with the

Drill rotation circumferential movement forces, whereby the material is eroded faster and moreover fine-grained to flour-like at the bottom and without drilling with a blow is used.

The tip 23 extends over the entire main cutting edge

22 and ends at a certain radius with its free End in an endpoint. The tip 23 thus increases over the entire skin cutting edge 22 from both radial sides to the free end point.

In the embodiments of the cemented carbide insert 2, the tip 23 passes radially from the inside and radially from the outside

Free-running surfaces 24 of the main cutting edge 22 defined. Here, as exemplarily shown in Figures 1 - 4 and 7, the freewheeling surfaces 24 are non-curved side surfaces of the cutting edge 25 of the main cutting edge 22 in each case at a certain wedge angle to the drill rotation axis d against

Drop drilling direction b. With regard to a radial axial plane, which in FIG. 3f is the same as the image plane, the main cutting edge 22 has a gable profile profile. In Figure 3f is to illustrate the nachförmigen

Profile cutting of the main cutting edges 22 with tip 23 of the

Profile course of the here right main cutting edge 22 without a tip 23 is shown in dashed lines and designated 22 ^λ . These two profiles form a triangle with a height h. Immediately apparent from the drawing is that the lower the inner angle enclosed by the tip 23 and the greater the height h of the drawn triangle, the greater is the lateral force produced by the tip 23 during drilling. The cutting edge 25 of the main cutting edge 22 with tip 23 is guided by the associated freewheeling surface 24 and the sloping towards drilling direction b and in the direction of rotation r facing side surface 26th

educated. Thus, the tip 23 has the shape of a

three-sided pyramid with the two freewheeling surfaces 24 and the side surface 26 as pyramidal side surfaces. However, the proportions shown in the figures are only

By way of example, without wishing to limit the disclosure content of the invention thereto.

Alternatively, the tip 23 defining the

Freewheeling surfaces 24 may be formed concave, such as it is shown by way of example in FIGS. 5 and 8. As in FIG. 3f, the profile profile of FIG

Main cutting edge shown in a side view perpendicular to the radial axial plane, which is also the image plane of Figure 5a. Hereafter is the profile course

roof gable, but with curved "gable sides", i. with two concave arcs converging in the tip. In this case, the exact profile profile is introduced by cylindrical grinding, whereby at the same time the wedge angle is defined by this. This will, in the

Compared to the embodiments of the cemented carbide insert 2 with non-curved freewheeling surfaces 24, a sharper tip 23 is created that proceeds more aggressively, however

more susceptible to wear. As can be clearly seen in particular from FIGS. 3f and 5a, the tip 23 divided the main cutting edges 22 into two radial sections, that is to say a radially outer section a1 and a radially inner section a2, the ratio of the lengths of the outer section a1 to the inner section a2 here is about 1.5.

Notwithstanding the embodiments of the cemented carbide insert 2 according to FIGS. 1-6, those of FIGS. 7 and 8 have only a single one in each of the two main cutting edges 32

However, the tips 33 are at different radii, i.e., as shown in Figure 7a, the left tip 33 on a first

Radius rl and the right tip 33 on a second radius r2, are arranged, wherein the first radius rl is here about half as large as the second radius r2. This causes the right here right tip 33 because of their larger radial

Lever (r2) the generation of a larger lateral force than the left peak 33rd

The centering tip 21 is formed pointed axially symmetrical to the drill axis d. This is for each Main cutting edge 22, radially inwardly and the cutting edge 25 of the main cutting edges 22 Bohrdrehrichtung r leading, a to the associated conveyor coil 14 of the respective main cutting edge 22 extending toward groove-like first recess 271 is provided. The first recess 271 is introduced into the hard-metal insert 2 to form an inner region and thus parallel to this inner region. Thus, the main cutting edge 22 is extended into the centering point 21 and further ensured that cut from the centering 21 material can be removed into the respective conveyor spiral into it.

Further, the first recess 271 is inclined at an angle γ to the drill rotation axis d. As can be seen, for example, from FIGS. 6c and 6d, the two main cutting edges 22 run radially inwards, forming a transverse cutting edge 28, wherein they are radially spaced over the transverse cutting edge 28, depending on the size of the setting angle γ. A comparison of FIGS. 3 a, 6 a and 6 c shows that the larger the angle of attack γ or the farther the first recesses 271 extend to the drill rotation axis d, the smaller is the transverse cutting edge 28. Thus, the inclination of the first recess 271 can be targeted Size of the transverse cutting edge 28 and thus the radial thickness of the centering tip 21 can be adjusted. The groove-like first recess 271 forms the radially inner region 221 of the one main cutting edge 22 and a radially inner region 241 of a freewheeling edge 242 delimiting the freewheeling surface 24 of the other main cutting edges 22.

In the embodiments of the illustrated here

Rock drill 1 and the carbide insert 2, the centering ß is about 120 ° and is thus in particular to

Drilling of floor tiles, thermosets, hard composites and the like suitable.

In the embodiments of the cemented carbide insert 2 according to the

FIGS. 6-8 is in addition to the first recess 271 extending radially outward and to the cutting edge 25 a second recess 272 for further improved Schnittgutabfuhr provided which extends against the boring direction b to the respective associated conveyor coil 14 out. The two recesses 271,272 of a main cutting edge 22 adjoin one another to form a discontinuity in the radial course of the associated main cutting edges 22, which likewise contributes to the comminution of the cut material. Favorable in terms of maximum size reduction is provided here that in all embodiments of the carbide insert 2 shown here, the radial point P, at which the two recesses 271,272 radially adjoin one another, is unequal to the point at which the tip 23 terminates in its free end.

To get as free flow of the cut off

Materials from the carbide insert 2 in the respective

To ensure delivery spiral 14 of the rock drill 1 is axially in the drilling direction b trailing to the respective

Main cutting edge 22 an excavation 29 (in particular Figures 1, la, 2 and 2a and in the bottom views of Figures 3e and 4e) provided, the boring direction b almost

seamless, i. without pointing in the direction of drilling b and away in the for the removal of the material

protruding side surface, merges into the associated conveyor spiral. That is, in the embodiments of the carbide insert 2 shown here is only one for the

Material flow harmless offset in the transition of the

Carbide insert 2 provided in the conveyor coil 14.

As far as a second recess 272 is provided, it leads the clippings against drilling direction b in the

associated excavation 29. Further, the first recess 271 leads the clippings in the associated second recess 272 and radially inwardly directly into the associated excavation 29. Thus, a comprehensive removal of the clippings in the associated conveyor coil 14 is made possible. The carbide insert 2 is radially dimensioned and arranged in the receptacle 12 so that it is flush with the outside of the drill body 11 radially outward.

Carbide insert and rock drill

LIST OF REFERENCE NUMBERS

1 rock drill

11 drill body

12 recording

13 work ends

14 conveyor spiral

2 carbide insert

21 center point

22 main cutting edge

221 inner area (main cutting edge)

23 tip

24 freewheeling area

241 inner area freewheeling area

25 cutting edge

26 side surface (cutting edge)

271 first recess

272 second recess

28 cross cutting edge

29 levy

interior angle

ß centering angle

γ angle of attack

al outer section

a2 inner section

b Drilling direction

d drill rotation axis

h height

r drilling direction

rl first radius

r2 second radius

P point

Claims

Carbide insert and rock drill claims

1. A cemented carbide insert (2) for a rock drill (1) used for drilling rock, rocky material,

Hard plastic, glass or the like as a non-impact twist drill with a cylindrical

Boring body (11) and a carbide insert (2) having the working end (13) is formed, wherein the hard metal insert (2) two with respect to a

Drill rotational axis (d) radially opposite one another and with the formation of a centering tip (21) angularly arranged to each other main cutting edges (22), each having a rotating conveyor coil (14)

That is, the main cutting edges (22) are formed asymmetrically with respect to each other, at least one of the main cutting edges (22) being asymmetric with respect to each other

Main cutting (22) defined over its radial course in a spaced-apart from their radial ends central region in the drilling direction (b) projecting tip (23).

2. carbide insert (2) according to claim 1, d a du r c h

The tip (23) of the at least one main cutting edge (22) is defined radially inwardly and radially outwardly by an unbending or by a concave freewheeling surface (24).

3. carbide insert (2) according to one of the preceding

Claims, characterized in that the tip (23) divides the main cutting edge (22) into two radial sections, ie a radially outer section (al) and a radially inner section (a2), wherein the ratio of the lengths of the outer portion (al) to the inner portion (a2) <1, preferably ^ 1/2 or <1/3.

The cemented carbide insert (2) according to one of the preceding claims, characterized in that the centering tip (21) is designed to be sharpened axially symmetrically with respect to the drill rotational axis (d).

A cemented carbide insert (2) according to claim 4, characterized in that radially inwardly and to the cutting edge (25) of the main cutting edge (22) in FIG

Bohrdrehrichtung (r) leading to a to the associated conveyor coil (14) extending into a groove-like first recess (271) and / or radially outward and the cutting edge (25) of the main cutting edge (22) in the direction of rotation (r) leading one into the associated conveyor coil (14) extending into a groove-like second recess (272) are introduced into the drill body (11).

The cemented carbide insert (2) according to claim 5, wherein the two are in the state of the art

Recesses (271, 272) each form a profile section of the associated main cutting edge (22) and radially adjoin each other while forming a discontinuity in the radial course of the main cutting edge (22).

Cemented carbide insert (2) according to claim 6, characterized in that by the adjacent recesses (271, 272)

is formed discontinuity at a radial point (P) of the main cutting edge (22), which is different from the free end point of the tip (23) of this main cutting edge (22).

Carbide insert (2) according to claim 6 or 7, since it is characterized in that the point (P) with the discontinuity of the main cutting edge (22) formed by the adjacent recesses (271, 272) is disposed radially inward of the tip (23) of this main cutting edge (22).

The cemented carbide insert (2) according to one of claims 6 to 8, wherein the first recess (271) and / or second recess (272) are arranged in the drilling direction (b) at an angle to the drill rotation axis (d).

A cemented carbide insert (2) according to any one of the preceding claims, wherein each of the two main cutting edges (22) is in each case the same as in

Drilling direction (b) projecting tip (23), wherein the tip (23) of the one main cutting edge (22) on a first radius (rl) are arranged, which is not equal to a second radius (r2) of the tip (23) of the other main cutting edge (22) is.

A cemented carbide insert (2) according to claim 10, characterized in that the tip (23) of the one main cutting edge (22) on the radially inner half of the main cutting edge (22) and the tip (23) of the other main cutting edge (22) on the radially outer one Half of the other main cutting edge (22) are arranged.

Carbide insert (2) according to any one of the preceding claims, characterized in that the centering tip (21) has a centering angle (β) suitable for drilling, for example glass, preferably 50 ° to 70 °, for example for wall tiles 70 ° to 80 ° orfor drilling

For example, floor tiles, thermosets and

Hard composites 110 ° to 140 °.

13. The cemented carbide insert (2) according to one of the preceding claims, characterized in that it is plate-shaped.

14. Rock drill (1) working as without impact

Twist drill for drilling rock, rock-like material, hard plastic or glass is formed, wherein the rock drill (1) has a cylindrical

Drill body (11) and a working end (13) with a cemented carbide insert (2) according to one of claims 1 to 13.

15. Rock drill (1) according to claim 14, wherein the

Carbide insert (2) radially inwardly to the cutting edge (25) of the main cutting edge (22) in the direction of rotation (r) leading to the associated conveyor spiral (14) extending into a groove-like first recess (271) and / or radially outward to the cutting edge (25) Main cutting edge (22) in Bohrdrehrichtung (r) leading a in the associated conveyor coil (14) extending into groove-like second recess (272) are introduced into the drill body (11), as you rch

e e, the recesses (271, 272) of the main cutting edge (22) oppose each other

Drilling direction (b) extend to this main cutting edge (22) associated conveying spiral (14) or in the main cutting edge (22) associated conveying spiral (14) open.

16. Rock drill (1) according to claim 15, d a du r c h

That is, the first recess (271) of the main cutting edge (22) against the drilling direction (b) into the second recess (272) associated with this main cutting edge (22) and this in turn against the

Drilling direction (b) in which this main cutting edge (22) associated conveying spiral (14) open.