DE10038039A1 - Masonry drill bit/chisel has a shortened lateral cutter with structured cutting edges and cutting surfaces to give an improved centering action on the start of drilling into concrete or rock etc - Google Patents

Abstract

The masonry drill bit and/or chisel, for a power tool, has a shortened lateral cutter (40) where the cutting edges (23,23';24,24') at the tool centering section (32) are aligned at an angle to the drill center axis (30). The radial cutting surfaces (16), near the step (34), are shortened by a value (a1) of one-third to three-thirds of a width (h1), parallel to the center plane (30).

Description

The invention relates to a drilling and / or chiseling tool the preamble of claim 1.

State of the art

Conventional drilling tools and in particular rock drills consist of a drill shank and a drill head, in which a hard metal cutting element, which is roof-shaped in side view, is inserted (see, for example, FIG. 1 of EP 0 452 255 B1 (HILTI)).

The hard metal cutting element has wedge-shaped cut edges or rake faces on both sides of the roof-shaped end face, the upper cutting edge lying on a conical envelope. The front rake face in the direction of rotation with a negative rake face angle and the free face behind the cutting edge of each radially extending cutting edge are laterally offset with respect to a vertical plane of symmetry, so that so-called cross-cuts are created (see Fig. 2 of EP 0 452 255 B1).

The one in the direction of rotation in front of the front cutting edge arranged rake face usually has one Cutting angle or rake face angle of approx. 60 ° Free area behind the cutting edge on the front usually an open area angle of approx. 20 to 30 °  on, with the angles facing a vertical plane the longitudinal axis of the drill can be measured.

The one made of hard metal or another hard material roof-shaped insert passes through the drill head completely over its entire diameter and forms in as a rule, an additional lateral overhang for Formation of the nominal diameter. The transition area from the Drill helix to the drill head is a support area for one such cutting plate formed. The Tungsten carbide insert mainly on their open space indicative back by a support body in the Drill head supported against breaking out.

Such carbide inserts are also used Manufacture of drill bits made like this is shown for example in DE 689 18 369 T2. there is the chisel effect by an essentially striking generated instead of rotating the tool. Drilling tools in hammer drills are generally with a superimposed, rotating drilling and axially striking Chisel movement applied. With a combined drilling and striking or chiseling strain of a Drilling tools occur particularly when drilling Boreholes centering problems. For good centering of the drilling tool should be the carbide insert taper as possible. A good chisel effect striking stress is by means of a possible flat chisel edge achieved, d. H. with a tip angle of about 180 °. Usual carbide inserts are included equipped with a tip angle of approx. 130 ° reasonable compromise between these needs achieve.

Tungsten carbide inserts from rock drills have in their radially inner area due to the smaller  Peripheral speed a lower drilling capacity than in its radially outer area, where the Peripheral speed is greatest. Furthermore, the Carbide insert with its radially outer axial side edges guiding properties for guiding and Centering the drilling tool.

EP 0 715 055 A2 describes a drilling and / or chiseling tool after the genus of claim 1 become known at which the carbide insert on its axial Front end has gradations, so that the original roof-shaped cutting edge is divided into several cutting parts. The inner area of the hard metal Insert designed unchanged and serves in Good centering of the drilling tool. The radially outer area of the two cutting edges of the Cutting plate has a gradation, which makes this Cutting area either roof-shaped or flat is. The disadvantage of this tool is the poor quality Coordination of the different cutting edges with each other Achievement of an optimal effect of the tool. This is playing however, in the task set in this prior art and its solution doesn't matter.

Reference is also made to DE 299 02 665. Here the in their basic conception roof-shaped carbide insert in its radially inner region, d. H. in the field of Drill tip designed as a flattening, with additional a pronounced central flattened chisel tip by V- shaped constrictions in the cutting edges to the side of the Carbide tip is achieved. The side The transition area of the constrictions includes one Tip angle of about 90 ° so that the conical Envelope has corresponding V-shaped constrictions. The outward-facing edges of the constrictions run approximately perpendicular to the longitudinal axis of the drill, d. H. the usual  Top angle of the envelope curve from approx. 130 ° to 180 ° enlarged. The disadvantage of this embodiment is that Fact because the centering effect in the area of Drill center axis through a flattening at the point is eliminated where it is usually in the central area is needed. In addition, the constriction with a acute angle of about 90 °, which is also one prevents good centering. After all, they are provided constrictions to the side of the middle flattened carbide tip with only one outward pointing short edge perpendicular to the central axis trained that in the radially inner area too comes to lie. In this area, however, is the chisel effect of such a drilling tool to be classified as rather low.

Object, solution and advantages of the invention

The invention has for its object a drilling and / or To propose chisel tool, which is an extremely good one Has centering effect when drilling and in which the Centering effect and chisel effect as drilling progresses is increased.

This task is based on a tool after Preamble of claim 1 by the characterizing Features of claim 1 solved.

In the subclaims are advantageous and expedient Developments of that described in claim 1 Tool specified.

The invention is based on the knowledge that a optimal effect of a drilling or chiseling tool only then can be achieved when the task of centering especially at the beginning of the drilling process and during the Drilling progress and the task of striking chisels to  Removal of the cuttings through constructive measures be separated from each other, with the areas of responsibility supplement and can overlap in terms of tools. The Tungsten carbide insert to exercise a good Centering effect in its radially inner area, d. H. more pointed than flat in the area of the longitudinal axis of the drill be formed. The tool according to the invention has consequently a central drill tip with a possible small chisel edge in the area of the longitudinal axis of the drill.

Good guiding properties of a hard metal insert are also generated by side edges, which are usually due to the radially outer, axially parallel outer surfaces a hard metal insert. These areas however, they are only used with a delay when tapping. According to the invention, the central carbide tip is therefore used also equipped with side guide surfaces that run almost axially parallel and thus also to one contribute to good tool management. The one in the contour roof-shaped hard metal insert accordingly instructs their radial cutting edges known per se, but which are optimized in their shape. The each at a gradation provided on the side is the centric carbide tip with a possible wall parallel to the axis or parallel to a central plane equipped to improve the centering properties. The in addition to the gradation generated radially outer area of the Carbide cutting edge should radially as far as possible extend outside, this one due to the gradation shortened length compared to the original on the has conical envelope lying cutting edge. A shortened length of the cutting edge thus formed is all the more the more effective the flatter it is, d. H. the original tip angle of the envelope of the carbide Cutting plate increases up to 180 °. Hereby in extreme cases the constriction forms a side view  on the insert horizontal and vertical area, the horizontal area most likely being a chisel embodies while the vertical range corresponding Guiding properties and centering properties takes over.

Through these measures, the drilling tool in the area of Drill tip optimized in its effect.

The gradation according to the invention in the cutting Tungsten carbide cutting tip to form a central one Centering tip and a radially outer striking or chiseling drill head area is selected such that these extend axially over the entire length axial width of the rake face with negative rake angle can extend. This range can be a third to that cover the entire width of this rake face. The stronger or the lower the gradation is chosen, the more enlarged the point angle formed or imagined thereby, the can run up to 180 °, d. H. one perpendicular to Drill longitudinal axis arranged cutting edge forms.

Further details and advantages of the invention emerge from the following description of exemplary embodiments of the invention, which is explained in more detail with reference to the drawings become.

Show it

Fig. 1 is a side view of an inventive drilling and / or chisel tool with inserted cutting body in the region of the tool head,

FIG. 1a is a plan view of the tool of FIG. 1,

Fig. 2 is a side view of the drilling tool of FIG. 1,

FIG. 2a is an enlarged view of detail A in Fig. 2,

FIG. 2b shows a plan view of the tool as shown in Fig. 2a,

Fig. 3a shows a side view of the hard metal cutting plate in the detail view of Fig. 1,

FIG. 3b, the hard metal cutting plate according to Fig. 3a in side view,

Fig. 3c, the hard metal cutting plate according to Fig. 3a, in plan view,

FIGS. 4a to 4c show a further embodiment of the hard metal cutting plate according to Fig. 3a to 3c and

FIGS. 5a to 5c show a further embodiment of the hard metal cutting plate according to Fig. 3 and 4.

Description of the embodiments

The drilling and chiseling tool according to the invention is hereinafter referred to as "rock drill". The rock drill 1 shown in side view in FIG. 1 and in its side view in FIG. 2 consists of a drill head 2 , as shown in more detail in FIGS . 2a, 2b according to detail A in FIG. 2, of a helical shaft 3 and a clamping shaft or clamping end 4 . The clamping shaft is designed as an SDS-plus clamping shaft.

The basic design of the drill head 2 has a roof-shaped hard metal cutting plate 5 which, with its outer, axially extending side edges 6, forms the nominal diameter D of the drilling tool. The helical shank 3 in turn has a diameter d ₁ , the clamping shank 4 a diameter d ₂ , it being possible for a stepped diameter d ₂ , d ₂ ′ of the clamping shank to be provided, depending on the size of the drill. The helix pitch is marked with the pitch angle α. The longitudinal axis of the drill bit bears the reference number 7 .

In the exemplary embodiment according to FIGS . 1 and 2, at least the helical shaft 3 is made from a blank produced without cutting such as, for. B. an extruded part or a forged part or a drawn blank and has a so-called wing profile, as shown in Fig. 2b in plan view. With regard to the structure, the type of manufacture and the use of the hard metal cutting insert in such a twisted wing profile, reference is made to the applicant's earlier application according to DE 199 15 304, including the literature there. In particular, FIGS . 3a, 4a show a conveyor helical structure similar to that in the present invention. Likewise, FIG. 2 there shows an associated starting profile for the production of such a twisted conveyor helix.

As shown in FIGS. 1 and 2, a hard metal cutting plate according to the invention prepared is used of such a drilling tool in a drill head 2 5. Due to the extremely narrow design of the wings 8 , 9 of the wing profile 10 , the hard metal cutting insert 5 in the exemplary embodiment as shown in FIGS . 2a, 2b is only embedded on the respective rear side 11 , 12 in the drill head, while the hard metal front side 13 , 14 is exposed in the region of the respective radially extending rake face 15 , 16 . The support of the rake face 15 , 16 in the drill head only begins in the area of the core diameter d ₃ , as can be seen in the areas 17 , 18 from FIG. 2b.

The rear support surface 19 , 20 of the wings 8 , 9 supports the hard metal cutting plate behind the free surfaces 21 , 22 . The end cutting edge provided between the rake face and the free face is designated by reference numerals 23 , 24 . The basic structure of the roof-shaped hard metal cutting plate 5 has a conical envelope curve 25 with an included apex angle γ, which forms a right cutting edge 25 and left cutting edge 26 in FIG. 1. The cutting edge 25 has the cutting surface 15 and the free surface 21 , the cutting edge 26 has the cutting surface 16 and the free surface 22 . The direction of rotation of the tool is indicated by arrow 27 .

Because of the slender wings 8 , 9 of the wing profile, the straight run-up 28 shown in FIG. 2a, which extends axially upward and which has a thickness d ₄ that is approximately 0.8 to twice the plate thickness, is formed at the end of the conveyor helix 3 d _{5 of} the hard metal insert 5 . The main webs 29 of the helical shaft 3 formed by the wing profile 8 , 9 in turn have a width or thickness d ₆ which correspond approximately to the width d _{4 of} the straight run-up 28 .

The drilling tool accordingly has an extremely slim drill head due to the twisted wing profile, the shape of the hard metal cutting tip 5 being adapted to such a slim profile. In particular due to the small guide surface of a drill constructed in this way, the hole quality and the drilling behavior can be greatly improved by installing a hard metal plate according to the invention.

The embodiment shown in FIGS . 1 and 2 shows a hard metal cutting plate 5 , as is shown in more detail in FIGS . 3a to 3c and is explained below. The same parts are provided with the same reference numerals.

Fig. 3a shows the hard metal cutting plate in its broad side view analogous to the view in Fig. 1. Separated by the center plane 30 has in the initial shaping hard metal cutting plate roof-shaped in a right (25) and left (26) cutting edge. Reference number 31 shows a conical envelope curve with a tip angle γ, 130 °, on which the cutting edges of a commercially available cutting insert run.

The hard metal cutting insert 5 according to the invention is divided into a radially inner centering section 32 with the radius r ₁ or the length l ₁ and two radially outer sections 33 , 33 'with the length section l ₂ . The transition from the centering section 32 to the outer sections 33 , 33 'is effected in each case by a step 34 , which forms an axially parallel cut edge 35 , 36 in the region of the rake face 15 , 16 , the axial length a _{1 of} this cut edge being shown in FIG. 3 shown side view takes about a third (see FIG. 5a) to about three thirds (see FIG. 4a) of the height h ₁ projected into the plane of the drawing.

The incision edge 35 , 36 is continued in the rear free surface 21 , 22 and thus forms incision surfaces 37 , 38 which form an undercut by the angle δ ₁ ≅ 5 to 10 °.

The incised edges 35 , 36 shown in FIG. 3 a therefore lie in the inclined plane of the respective rake face 15 , 16 and span a plane 35 ′, 36 ′ that is parallel to the central plane 30 .

Instead of a parallel arrangement of the planes 35 ', 36 ', these can also meet at a small angle on the order of 5 to 10 ° in the upper or lower area of the drill tip. This means that the axially parallel surfaces can be tilted slightly outwards or slightly inwards.

The incision 34 deflects the cutting edges 23 , 24 of the rake faces with a negative rake angle β ₁ from the envelope curve 31 by an angle δ ₂ . As a result, the actual length of the cutting edge 23 , 24 in the outer section 33 , 33 'is shortened to a length l ₃ , as a result of which the cutting edge 23 , 24 obtains an increased chiseling effect due to its flatter inclination. The flatter the cutting edges 23 , 24 , ie the larger the angle δ ₂ is, the greater the removal rate of the drilling tool. The tip angle γ ₁ enclosed by the intersecting cutting edges 23 , 24 consequently increases as a result of the gradation 34 from a value of γ ₁ ≅ 130 ° to 180 °, that is to say the cutting edges 23 , 24 run vertically at a tip angle of γ ₁ = 180 ° to the vertical plane 30 , as shown in FIG. 4a.

The hard metal cutting tip according to the invention therefore consists of a central or radially inner centering area 32 with steps 34 largely parallel to the central plane 30 , which enable a high centering effect and guidance of the drilling tool, in particular during drilling. The gradations cause a shortening and a flat position of the end cutting edges 23 , 24 of the rake faces 15 , 16 in the sections 33 , 33 'lying radially next to the centering section 32 . In these areas, due to the higher peripheral speed of the cutting plate, a high material removal takes place, which is favored by the flat position of the cutting edges.

The length sections 32 , 33 are chosen such that the two outer sections 33 , 33 'have a length l ₂ , the sum of which is equal to or more than the length l _{1 of} the centering section 32 , in particular r ₁ = ½. l ₁ ≈ (0.5 - 1). l ₂ is.

The centering section 32 also has conventional cutting edges 23 ', 24 ' which are arranged on the conical surface 31 . Due to the cutting edges 23 ', 24 ' which are offset by the amount a ₂ from the transverse symmetry plane 39 , a cross cutting edge 40 results which connects the two cutting edges 23 ', 24 ' to one another. The width b _{2 of} the transverse cutting edge 40 is reduced in that the cutting edges 23 '24' do not run parallel to the transverse symmetry plane, but at an angle δ ₃ thereto (see FIG. 5c). The transverse cutting edge b ₂ should be made as small as possible to form a centering tip.

As shown in Fig. 3a to 3c, the hard metal cutting plate in its radially outer region a chamfer 41 on. This chamfer can either lie on the conical surface 31 or be formed by a separate bevel or shape.

The embodiment according to Fig. 4a to Fig. 4c differs from the embodiment of Fig. 3a to 3c by a more pronounced gradation 34 to one in Fig. Course 4a shown of the cutting edges 23, 24 leads, which is about perpendicular to the center plane 30 . The tip angle thus formed increases to γ ₂ ≈ 180 °.

The conical envelope 31 encloses the cutting edges 23 ', 24 ' of the central centering section 32 . In the exemplary embodiment according to FIG. 4, the two cut edges 35 , 36 run slightly inclined upward and enclose an angle of ε ≅ 5 to 15 °.

The incision or the step 34 shown in the exemplary embodiment according to FIG. 4 extends over the entire width b _{1 of} each rake face 15 , 16 and touches the lower rake face edge 42 at point 43 .

In the radially outer region, the envelope curve 31 can in turn coincide with the cutting edge 23 ″, 24 ″ over a length section a ₃ . The step 34 should not be extended beyond the lower rake surface edge 43 .

The free surface 21 , 22 lying behind the respective cutting edge 23 , 24 also has a negative free surface angle β ₂ in order to counteract tilting of the tool.

When in Fig. 5a to Fig. 5c variant embodiment shown for a hard metal cutting plate 5, the gradation 34 is only about a vertical portion A ₁ of the projected into the plane of height h _{1 is} executed, which is about 1/3 to 1/2 of the height h is ₁ . The cutting edges 23 ', 24 ' of the centering section 32 again lie on a conical surface 31 with a tip angle γ ≅ 130 ° -150 °. Because of the additional guiding properties through the gradations 34 , the tip angle γ can also be made greater than 130 °, ie γ ≧ 130 °. The steps 34 in turn form cut edges 35 , 36 which lie in planes 35 ', 36 ' which are parallel or approximately parallel to the central plane 30 . As a result, as in FIGS. 3 and 4, axially parallel guide edges to the side edges 6 of the hard metal cutting plate are again formed. The radially outer cutting edges 23, 24 of the clamping surfaces 15, 16 of the outer portions 33, 33 which extends 'run in the embodiment of FIGS. 5a to Fig. 5c on a conical surface 31' at a distance a ₄ to the conical surface 31.

As shown in the exemplary embodiment according to FIG. 5c, the transverse cutting edge 40 is reduced in width by the cutting edges 23 , 23 ', 24 , 24 ' tapering obliquely towards the central axis of the drill, ie the rake face 15 , 16 increases in area towards the center there. This also improves the centering effect of the hard metal insert. The width b _{1 of} the rake faces 15 , 16 consequently increases towards the center. Starting from the side edges 6 of the hard metal cutting plate 5 , the rake face 15 , 16 widens continuously until the cutting edges 23 ', 24 ' transition into the transverse cutting edge 40 .

The invention is not shown on and described embodiments limited. It includes also rather all further training and professional Refinements in the context of property rights claims.  

Reference list

1

Rock drill

2nd

Drill head

3rd

Spiral shaft

4

Fixture

5

Carbide insert

6

Side edges

7

Drill longitudinal center axis

8th

wing

9

wing

10th

Wing profile

11

back

12th

back

13

front

14

front

15

Rake face

16

Rake face

17th

Points / area

18th

Points / area

19th

rear support surface

20th

rear support surface

21

Open space

22

Open space

23

Cutting edge

24th

Cutting edge

25th

Cutting edge

5

26

Cutting edge

5

27

arrow

28

straight start

29

Main walkway

30th

Middle plane

31

Envelope

32

Centering section

33

,

33

'' outer sections

34

gradation

35

Cut edge

36

Cut edge

37

Incision surfaces

38

Incision surfaces

39

Transverse symmetry plane

40

Chisel edge

41

Chamfer

42

Rake edge

43

Point

Claims (12)

1. drilling and / or chiseling tool, in particular for processing concrete, stone, masonry and the same materials, with a cutting body or cutting plate ( 5 ) contained on the processing side in the tool head ( 2 ), the cutting body ( 5 ) being roof-shaped, radially extending Cutting ( 25 , 26 ) as well as rake faces ( 15 , 16 ) and free surfaces ( 21 , 22 ), wherein lateral steps ( 34 ) with incision edges ( 35 , 36 ) are provided to form a radially inner centering section ( 32 ) respective rake face ( 15 , 16 ) lie on incision planes ( 35 ', 36 '), which run approximately parallel to a tool center plane ( 30 ) or enclose an angle ε, characterized in that a shortened transverse cutting edge ( 40 ) is formed by the Cutting edges ( 23 , 23 'or 24 , 24 ') of the centering section ( 32 ) run obliquely towards the drill center axis ( 30 '). 2. Tool according to claim 1, characterized in that the radially extending rake faces ( 15 , 16 ) of the cutting edges ( 25 , 26 ) in the region of the gradation ( 34 ) by an amount (a ₁ ) of one third to three thirds of a width ( h ₁ ) is shortened, which is aligned approximately parallel to the central plane ( 30 ). 3. Tool according to claim 1 or 2, characterized in that the step ( 34 ) is formed by an approximately parallel to a central plane ( 30 ) incision in the respective rake face ( 15 , 16 ), which is in the respective free surface ( 21 , 22nd ) continues, the conical surface or surface ( 31 , 31 ') extending through the cutting edges ( 23 , 24 ) formed at the end forming an angle of γ ₁ ≅ 130 to 180 °. 4. Tool according to one of the preceding claims, characterized in that the central centering section ( 32 ) has cutting edges ( 23 ', 24 ') which lie on a conical envelope ( 31 ) with a tip angle γ ≅ 130 ° -150 °. 5. Tool according to one of the preceding claims, characterized in that the centering section ( 32 ) has a diameter 11 which corresponds to approximately half to a quarter of the nominal diameter D. 6. Tool according to one of the preceding claims, characterized in that the rake faces ( 15 , 16 ) and / or the free surfaces ( 21 , 22 ) have chamfers ( 41 ) in the radially outer region of the hard metal insert. 7. Tool according to one of the preceding claims, characterized in that the gradations ( 34 ) lie on incision surfaces ( 37 , 38 ), the machining side or clamping side an angle of ε ≅ 5 ° to 20 ° and in particular ε ≅ 15 ° to 20 ° lock in. 8. Tool according to one of the preceding claims, characterized in that the incision surfaces ( 37 , 38 ) of the gradations ( 34 ) form a clearance angle δ ₁ ≅ 10 °. 9. Tool according to one of the preceding claims, characterized in that the cutting body ( 5 ) or the cutting plate ( 5 ) is inserted into a drilling tool with a helical shaft ( 3 ), the helical shaft ( 3 ) preferably consisting of a twisted rod profile or wing profile consists. 10. Tool according to one of the preceding claims, characterized in that the cutting edges ( 23 ', 24 ') of the centering section ( 32 ) with respect to a transverse plane of symmetry ( 39 ) are offset by an amount a ₂ , with a transverse cutting edge ( 40 ) the cutting edges ( 23 ', 24 ') connects to one another in such a way that the width b _{2 of} the transverse cutting edge ( 40 ) is reduced by the fact that the cutting edges ( 23 ', 24 ') run at an angle δ ₃ (step angle) to the transverse symmetry plane ( 39 ). 11. Tool according to one of the preceding claims, characterized in that the angle δ _{3 has} an amount of 0 ° to 5 °. 12. Tool according to one of the preceding claims, characterized in that the rake face ( 12 , 13 ) from the radially outer side edge ( 6 ) of the hard metal insert ( 5 ) continuously or continuously to approximately the central plane of symmetry ( 30 ) or longitudinal axis of the drill bit ( 7 ) extends, in particular the width of the rake face ( 15 , 16 ) varies.