Classifications

• • E—FIXED CONSTRUCTIONS
  • E21—EARTH OR ROCK DRILLING; MINING
  • E21B—EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
  • E21B10/00—Drill bits
  • E21B10/44—Bits with helical conveying portion, e.g. screw type bits; Augers with leading portion or with detachable parts
  • E21B10/445—Bits with helical conveying portion, e.g. screw type bits; Augers with leading portion or with detachable parts percussion type, e.g. for masonry

Definitions

• the invention relates to a rock drill according to the preamble of claim 1.
• Conventional rock bores 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 FIG. 1 of EP 0 452 255 B1).
• the cutting element has wedge-shaped cut edges or rake faces on both sides of the roof-shaped end face, each with an upper cutting edge.
• the cutting edges 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 free surfaces arranged behind the cutting edge in the direction of rotation generally have a free surface angle of approximately 20 ° -30 ° in relation to a conventional cutting edge angle or rake surface angle of 60 ° of the rake surface, the angles being opposite a vertical plane the longitudinal axis of the drill can be measured.
• Such drilling tools sometimes have secondary cutting inserts or corresponding pins which are intended to serve the drilling progress.
• the roof-shaped cutting plate made of hard metal can penetrate the drill head completely over its entire diameter and usually forms an additional lateral protrusion to form the nominal diameter. If there are no secondary cutting inserts or corresponding pins, the transition area from the drill helix to the drill head is designed as a support area for the cutting insert.
• the carbide insert is laterally supported by a corresponding, voluminous support body in the drill head to prevent it breaking out, with storage areas generally forming on the end face for the removal of the drilling dust.
• the invention has for its object to improve a drilling tool according to the preamble of claim 1 that the drilling performance in concrete is improved.
• the aim is also to achieve a lower load on the hard metal cutting insert.
• the drill according to the invention has the advantage over the known tools that a significantly better penetration into the concrete is achieved by less "blunt" cutting. This immediately results in faster drilling progress.
• the impact power acting on the drilling tool is not transferred to a conventionally blunt hard metal insert, but rather the overall impact performance is converted even more effectively into drilling performance by a significantly slimmer embodiment of the drill head.
• smaller tool dimensions can also be used in larger rotary hammers without being damaged.
• the inventive design of the end face of the hard metal cutting insert also results in less stress on the hard metal cutting plate itself.
• An essential basic idea of the invention is to modify the free surface of the carbide insert arranged on the rear side of the respective rake face without any risk of a broken cutting edge. This is done according to the invention in that each open space is subdivided into at least two open space sections which, for. B. may have approximately the same widths, the indicative of the side wall of the hard metal insert free space portion z. B. can have an approximately twice as large a flank angle as the first flank section pointing towards the cutting edge. As a result, the free surface is tapered, so that the hard metal cutting tip is formed in a side view on its narrow side, tapering.
• the hard metal insert penetrates into the drill material with little resistance in an additionally overall more sharply shaped tool, so that the impact performance leads to faster drilling progress.
• for. B. provide a conventional hard metal cutting element on its respective free area with a second free area section, the free area sections in their upward projection length z. B. about halved.
• the free-space sections can be designed differently in terms of their projection lengths and their free-space angles.
• the rake face is formed with an enlarged rake face angle of> 60 ° and in particular approximately 70 ° compared to a conventional embodiment.
• the clamping surface can be flat or concave or convex.
• the tangential or aligned transition to the support surface for the carbide insert plays a role here.
• the hard metal cutting plate designed according to the invention with a second free surface angle is integrated in an independently protective further development of the invention in a drill head whose lateral support body for the hard metal cutting plate is very slim and also tapered.
• a drill head whose lateral support body for the hard metal cutting plate is very slim and also tapered.
• the lateral support surfaces as tapered as possible, in their outer contour z.
• the outer contour is flat, convex or concave, the support surfaces for the carbide cutting plate and thus the outer contour of the drill head merging almost or completely tangentially or asymptotically into the rake face or into the free surface of the hard metal cutting element .
• This measure on the drill head can also lead to the desired effect with a conventionally designed cutting insert.
• FIG. 1 is a perspective view of the drill head of a drilling tool according to the first embodiment
• FIG. 2 shows a side view from perspective A in FIG. 1 of the tool according to the invention, only the right half of FIG. 1 with its roof-shaped cutting plate being visible,
• Fig. 3a shows a conventional tool compared to 1 and 3b, to explain the prior art
• FIG. 4 shows a further exemplary embodiment of a drilling tool according to the invention with a varied head geometry
• 4a is an enlarged representation on a scale of 5: 1 of the representation of FIG. 4,
• FIG. 5 is a side view of the embodiment of FIG. 4,
• FIG. 5a is a plan view of the embodiment of FIG. 5,
• FIG. 7 is a perspective view of the illustration of FIG. 4 and 5.
• the rock drill 1 has a drill shaft 2, only indicated, and a drill head 3, which on its end face 4 pointing in the feed direction 16 has a cutting plate 5 which is generally roof-shaped in its broad side view and extends over the diameter D1.
• This cutting plate 5 has on both sides of its roof-shaped configuration with the angle ⁇ in the direction of rotation 8 pointing, wedge-shaped ground cutting edges or rake faces 6, 6 ', with a negative rake face angle ⁇ and a cutting edge 7, 7' formed on the end face.
• the so-called free surface 10, 10 ' is located on the back of the respective rake face 6, 6' with a free face angle of ⁇ about 20 ° to 30 ° as a normal value.
• the smaller value applies for drilling tools with a smaller nominal diameter (e.g. ⁇ 12 mm), the larger value for those with a larger nominal diameter.
• the rake face angle ⁇ is usually ⁇ ⁇ 60 ° in conventional tools.
• the known open area 10, 10 is now divided into two open area sections 11, 12.
• B. ⁇ 12 mm the larger value for the nominal diameter above.
• the flank angles ⁇ 1, ⁇ 2 are measured in relation to a plane 13 lying perpendicular to the drill axis 9.
• a similar geometrical design is provided from more than two open-space sections (polyline) or as a convex surface, which represents the limit case of the polygon.
• the first open area section 11 adjacent to the end cutting edge 7 has a projection length Si lying in the plane 13 and the adjoining second open area section 12 has a projection length S 2 , the sum of which is determined as length b.
• the ratio Si: S 2 can vary depending on the application and is not least chosen in coordination with the projection length S 3 of the rake face 6. For example, Sj_ ⁇ (0.4 to 0.7) xb.
• the end cutting edge 7 between the rake face 6 and the free face 11 of the hard metal cutting plate 5 is arranged eccentrically to the vertical center plane 14 of the cutting plate 5.
• the projection length S 3 of the rake face 6 can have a length of approximately 1/3 to 1/6, in particular 1/5 of the total width B of the cutting plate 5.
• FIGS. 3a, 3b From the representation of the prior art in FIGS. 3a, 3b it can be seen that large-volume support bodies 15, 15 'are provided on the side of the cutting plate 5 in order to prevent the cutting plate 5 from breaking out under load.
• This support body 15, 15 ' preferably results from a milling or grinding process on the drill head 3, with the carbide cutting plate on both sides in the drilling direction 16 wide surface sections 17, 18 result, which represent a kind of resistance surface or storage surface for the drillings in the prior art.
• these support bodies 15, 15 ' are made very tapered by a grinding process, so that
• the support side wall 19, 19 'of the drill head consequently forms a side flank with a curved or arched or cylindrical segment-shaped i.e. concave outer contour.
• the rake face angle ⁇ (also called the rake angle) in the Order of magnitude of ⁇ ⁇ 60 °, which corresponds to a normal value for a rake angle.
• the negative rake angle ⁇ of the rake face 6 is chosen between 60 and 80 ° and in particular ⁇ ⁇ 70 °. If it has previously been assumed that rake angle> 60 ° leads to increased wear and, in particular, to an increased risk of breakage of the hard metal insert, such a rake angle is preferably used consciously in the present invention.
• the rake angle ⁇ > 60 ° is carried out and in particular ⁇ ⁇ 70 ° is selected.
• the side walls 25, 25 'supporting the carbide cutting insert merge asymptotically or tangentially into the rake face 6, so that an overall slender head results without storage areas opposing the drilling dust.
• the second open area section 12 again passes tangentially or asymptotically into the further side wall 26, 26 ', so that an extremely slim drill head is formed on this side too, without storage areas opposing the drilling dust.
• the side walls 25, 26 and 25 ', 26' are separated by the fold line 27 (see FIGS. 5 and 7).
• FIG. 4a in an enlarged representation (5: 1) of FIG. 4, the lengths si to S 3 of the open-space sections 11, 12 and the rake faces 6 projected into the horizontal plane 13 are formed.
• the actual lengths of the flank sections 11, 12 or the rake face 6 result from the projection lengths S ! to S 3 divided by the cosine of the respective angle ⁇ 1, ⁇ 2 or ⁇ .
• a so-called cross cutting edge 24 results in the area of the central drill tip 23, as can be seen in particular in the top view from FIG. 5a. Due to its central arrangement in the area of the drill tip 23, this cross cutting edge 24 has practically none Peripheral speed and therefore acts like a pointed chisel. It is therefore a particularly advantageous development of the invention that the transverse cutting edge 24 is kept as small as possible in length 1 so that it acts as a tip as far as possible.
• the respective rake face 6, 6 ' is designed in accordance with the illustration in FIGS. 6a, b in such a way that its width, as seen in plan view, increases towards the drill tip 23 (see hatched area F). This leads to a Reduction of the cutting edge 24, that is length 1 is shortened. If this enlargement of the width towards the drill tip 23 is carried out on both rake faces 6, 6 ", then the length of the cross cutting edge shown in FIG Ideally, 1 »0.
• FIG. 6a shows the cutting plate 5 with a first free-area section 11 and a second free-area section 12, as described for FIGS. 1, 2 and 4 and 5.
• Fig. 6b only one free area 10 is shown symbolically, but also with a shortened cross cutting edge 24 due to the above facts.
• the second open area sections 12 can also increase towards the center in their width seen in plan view, in order to additionally lead to a reduction in the length 1 of the transverse cutting edge 24 (see area F).
• This is symbolically represented in FIG. 6c with the edge 28, 28 'between the first and second open-space sections 11, 12. In the ideal case, this in turn leads to an almost punctiform contact in the area of the drill tip 23.
• the rake face 6 is parallel in its width as seen in plan view trained to the outer surface.
• the measures according to the invention achieve the implementation of a slim drill head, in which both the rake angle ⁇ is increased compared to the conventional type and several open-space sections are provided.
• both the rake angle ⁇ is increased compared to the conventional type and several open-space sections are provided.
• a convexly curved outer contour for the free area 10 which represents a kind of “borderline traverse”.
• the decisive factor is the tapered arrangement of the insert with a stepless transition into the side wall of the drill head.
• Such a slim drill head opens as wide a channel as possible, whereby the drilling dust is offered as little resistance as possible.
• a slim drill head also does not reduce the life of the drilling tool.
• the opposite is more the case with the measures according to the invention.
• the explanation lies essentially in the fact that the enormous impact energy of the machine tool can be converted into the rock much better, whereby the tool is protected.
• the rake face 6 is additionally made slightly concave, ie with a rounded rake face, this can be an additional advantage.
• the radial curvature produces coarser chips, that is, the total amount of material removed is reduced, which also increases the service life.
• the advantage of the convex insert with convex rake face 6 is that the convex insert enables an even slimmer drill head.
• the overall stability must be kept in mind.
• the drilling capacity can be increased even further compared to the previously described embodiment, but the risk of head breakage increases.
• such an embodiment is extremely useful for special applications, in particular for soft or moist rock.
• harder concrete or larger pebbles or reinforcements in general are not processed with a convex insert.
• the invention can optionally also be formed with a single free surface 10 of the cutting plate 5, wherein this free surface 10 can be equipped with a steeper clearance angle than usual. Clearance angles between 35 and 50 ° and in particular 40 ° would have to be selected here.
• the drill head has one or more cutting plates or a secondary cutting plate and several secondary cutting elements, the main cutting plate and / or the
• Secondary cutting elements have the above-mentioned characteristic features.
• the invention therefore relates in particular to the protection of such hard metal cutting elements as such, without being restricted to a specific drill head geometry.
• ⁇ rake angle (rake angle; ß flank angle (clearance angle;

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• Engineering & Computer Science (AREA)
• Geology (AREA)
• Life Sciences & Earth Sciences (AREA)
• Mining & Mineral Resources (AREA)
• Physics & Mathematics (AREA)
• Environmental & Geological Engineering (AREA)
• Fluid Mechanics (AREA)
• Mechanical Engineering (AREA)
• General Life Sciences & Earth Sciences (AREA)
• Geochemistry & Mineralogy (AREA)
• Earth Drilling (AREA)
• Drilling Tools (AREA)
• Steroid Compounds (AREA)

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• 1997
  • 1997-11-11 EP EP97949917A patent/EP0937191B1/fr not_active Expired - Lifetime
  • 1997-11-11 US US09/297,890 patent/US6260637B1/en not_active Expired - Lifetime
  • 1997-11-11 DK DK97949917T patent/DK0937191T3/da active
  • 1997-11-11 WO PCT/DE1997/002658 patent/WO1998021442A1/fr not_active Ceased
  • 1997-11-11 AT AT97949917T patent/ATE218180T1/de not_active IP Right Cessation
  • 1997-11-11 JP JP52204998A patent/JP3819439B2/ja not_active Expired - Fee Related

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