DRILL

Description

[0001] The present invention relates to a drill head for a drill for the percussive extraction of mineral building materials, as known from EP 1 944 108 A2 and described in the preamble of claim 1. The present invention also relates to a drill.

[0002] A drill for the percussive extraction of mineral building materials is known, for example, from EP1604793 A1. DISCLOSURE OF THE INVENTION

[0003] The drill bit for a drill according to the invention contains the features of claim 1 and has an upper side for extracting mineral material, a lower side for attachment to a shaft of the drill bit, and a rotation axis running centrally through the upper side and the lower side. The drill bit has arms, each having an end proximal to the rotation axis and an end distal to the rotation axis, and wherein the upper sides of the arms each have primary chisel edges running in the direction from the proximal end to the distal end. At least one, preferably at least two, of the arms have a secondary chisel edge on the upper side running along the primary chisel edge. The secondary chisel edge promotes the extraction of steel reinforcement in the rock.

[0004] According to the invention, the primary chisel edge and the secondary chisel edge of the same arm begin at the distal end of the arm. In contrast to the mining of the mineral material, the mining of the reinforcement is dominated by the outer regions of the drill head.

[0005] According to the invention, the primary chisel edge protrudes continuously from the secondary chisel edge of the same arm in the direction of impact, i.e., it is higher. During percussive mining, the secondary chisel edge comes into contact with the material somewhat later than the primary chisel edge. The primary chisel edge begins to shear off a portion of the reinforcement, which the secondary chisel edge can then bend.

[0006] According to the invention, the secondary chisel edge is offset from the primary chisel edge of the same arm in a direction of rotation of the drill head. One embodiment provides that the angle between the primary chisel edge and the secondary chisel edge of the same arm is less than 8 degrees. The two chisel edges are sufficiently close for the secondary chisel edge to capture the metal chip. SHORT DESCRIPTION OF THE CHARACTERS

[0007] The following description explains the invention using exemplary embodiments and figures. The figures show: Fig. 1 a drill, Fig. 2 a drill head, Fig. 3 a top view of the drill head, Fig. 4 a section through an arm of the drill head, Fig. 5 a top view of the drill head, Fig. 6 a section through an arm of the drill head, Fig. 7 a top view of the drill head

[0008] Identical or functionally equivalent elements are indicated by identical reference numerals in the figures, unless otherwise stated. EMBODIMENTS OF THE INVENTION

[0009] Fig. 1 shows an example drill 1. The drill 1 has a drill head 2, a spiral 3 and a shank 4. The drill 1 is designed for the extraction of mineral materials, especially reinforced concrete. The drill 1 is operated in one direction of rotation 5 around its longitudinal axis 6 (rotation axis). The typical direction of rotation 5 is when looking at the drill head 2 counterclockwise. The direction of rotation 5 is opposite to the drill 1can be used in a hand-held power tool that has a corresponding rotary drive. A percussion mechanism of the hand-held power tool periodically strikes a striking surface 7 on the exposed face of the insertion end 4. The shock wave of the blows runs through the coil 3 in direction of impact 8 to the drill head 2. The drill head 2 shatters the material. The rotary movement ensures, firstly, that the drill head 2 impacts the ground under different orientations and the drill hole is evenly drilled, and causes the drill bit shown 1 with spiral 3 removal of the drilling material from the borehole by means of the (transport) spiral 3. Instead of a spiral 3 the drill can 1 have a hollow cylindrical shaft. The drilled material is passed through the hollow shaft 3by means of a blower from the drill head 2 sucked out.

[0010] The body of the drill head 2 has a straight-prismatic basic shape with a star-shaped base surface. The basic shape is obtained by shifting the base surface parallel to the axis of rotation 6. The base area corresponds to the top view of the drill head 2, ie the silhouette of a top 9. The axis of rotation 6 runs centrically through the base surface, ergo centrically through a bottom 10 and the top 9 of the drill head 2.

[0011] A surface of the drill head 2 consists of the in the direction of impact 8 facing top 9, the top 9 opposite bottom 10 and the top 9 with the underside 10 connecting coat 11 together. The top9 is structured and has a tip 12 and several chisel edges 13 The tip 12 is preferably on the axis of rotation 6. The top 9 is used to break up and extract rock or other mineral building materials. The extraction is carried out primarily by impact driving the top 9 into the brittle materials. The underside 10 For example, it is flat, concave, or convex. The underside 10 is located on the Wendel 3 or another cylindrical shaft. The underside 10 For example, with the spiral 3 welded or soldered. Furthermore, the shaft can be provided with a slot for the positive fit of the drill head 2 The coat 11 is a connected drill head 2 circumferentially enclosing surface. The mantle 11consists of longitudinal, preferably parallel to the axis of rotation 6, oriented surfaces together.

[0012] The basic shape of the body can be geometrically divided into a compact, convex hull 14 and several arms 15 The compact hull 14 contains no cavities. The arms 15 are in the direction of rotation 5 through drainage openings 16 separated. The hull 14 can be assumed, for example, to be the largest cylinder (shown in dashed lines) that can be completely inscribed in the basic shape. The hull 14 lies on the axis of rotation 6. The summit 12 of the drill head 2 is preferably part of the hull 14.

[0013] The poor 15 are in different directions from the hull 14 off. The arms 15 are around the hull 14 and accordingly around the axis of rotation 6in the direction of rotation 5 arranged in a distributed manner. The drill head shown as an example 2 has four arms 15, Alternative drill heads can have two to six arms 15, preferably more than four arms 15 The arms 15 can be arranged at equal angles as shown 17 around the axis of rotation 6 be arranged, ie in the four-arm drill head 2 in angles 17 of 90 degrees. The four-arm drill head 2 has a strong preference for two-fold rotational symmetry. The smallest angles 17 between adjacent arms 15 can be between 60 degrees and 90 degrees. The six-arm drill head 2 also has a strong preference for two-fold rotational symmetry and is preferably mirror-symmetric. The smallest angles 17 between adjacent arms 15are between 45 degrees and 60 degrees. For a two-arm, three-arm and five-arm drill head 2 is the arrangement with equal angles 17 strongly preferred.

[0014] The poor 15 go into the hull 14 The transition area is called the proximal end 18 of the arm 15 A distal end 19 of the arm 15 is the axis of rotation 6 furthest away from the drill head 2. The radial distance of the distal end 19 defines the (outer) diameter 20 and surrounding area 21 of the drill head 2. An arm's length 15, ie the radial distance 22 the proximal end 18 from the distal end 19, is preferably larger than 1 / 6 of the diameter 20 of the drill head 2, e.g. larger than 1 / 4 of the diameter 20,and for example less than 3 / 8 of the diameter 20. The poor 15 of the exemplary drill head 2 are of the same design, especially of the same length.

[0015] The poor 15 can have a largely cuboidal basic shape. The exemplary arms 15 have opposite and exposed side surfaces 23, 24, which in the direction of rotation 5 or against the direction of rotation 5 The side surfaces 23, 24 range from the top 9 to the bottom 10 and are preferably parallel to the axis of rotation 6. The side surfaces 23, 24 can be flat as shown. The merging side surfaces 23, 24 neighboring arms 15 can form a concave section of the casing 11. A width 25 of the arm 15, ie a distance between the side surfaces 23,is smaller than the diameter of the hull 14. The opposite side surfaces 23, 24 are preferably parallel, less than 8 degrees, e.g. inclined less than 5 degrees.

[0016] The distal ends 19 the poor 15 form guide surfaces 26, which rest against the borehole wall. The guide surfaces 26 are essentially tangential to the circumference 21. The guide surfaces 26 are part of the coat 11 and preferably parallel to the axis of rotation 6. The guide surfaces 26 can be flat, or in the plane perpendicular to the axis of rotation 6 be convexly curved.

[0017] The drill head 2 is equipped with drainage openings 16 over which the top 9 The resulting drilling debris can be removed. The discharge openings 16 are openings that are within the perimeter 21arranged from the top 9 to the bottom 10 The drilling material flows from the top 9 in the discharge opening 16 towards the bottom 10 and thus to the shaft 3. For the example drill head 2 forms the concave section of the mantle 11 from the side surfaces 23, 24 the poor 15 the discharge openings 16. Each arm 15 is one in the direction of rotation 5 subsequent discharge opening 16 assigned. The discharge opening 16 separates in direction of rotation 5 a leading arm 15 from a trailing arm 15. The discharge opening 16 can be wider than the arm 15 The discharge openings 16 preferably reach to the hull 14 to get the one at the top 12 to efficiently remove the resulting drilling debris. A radial distance22 the discharge openings 16 from the axis of rotation 6 or lace 12 is preferably less than 1 / 4 of the diameter, e.g. less than 1 / 6 of the diameter 20, for example larger than 1 / 8 of the diameter 20.

[0018] The top 9 has arms 15, which have both primary chisel edges 13 as well as secondary chisel edges 27 The exemplary drill head 2 has four arms 15 each with a primary chisel edge 13 and a secondary chisel edge 27.

[0019] The primary chisel edges 13 run from the distal ends 19 the poor 15 towards the top 12. The chisel edges 13 begin adjacent to the guide surface 26. For the example drill head 2 the primary chisel edges run 13 to the top12 and thus extend over the entire radial dimension. The primary chisel edges 13 are continuous and uninterrupted. A course of the primary chisel edge 13 can be straight, especially over the length of the arm 15. The primary chisel edge 13 can be parallel to the side surface 24 The primary chisel edge 13 rise from the distal end 19 to the top 12, preferably continuously.

[0020] The primary chisel edge 13 is the line through the highest points of the arm 15 along a radial direction, ie from the distal end 19 to the proximal end 18 or to the top 12. The primary chisel edge 13 is the cutting line of a rake face 28 and an open space 29. The rake face 28 is opposite the open space 29in direction of rotation 5 leading. The rake face 28 is opposite the axis of rotation 6 inclined and rises against the direction of rotation 5 in direction of impact 8 continuously. The open space 29 points opposite to the direction of rotation 5 and falls against the direction of rotation 5 in direction of impact 8 continuously. A gap between the chip surface 28 and the open space 29 included roof angle 30 is greater than 45 degrees, preferably greater than 60 degrees and less than 120 degrees. The roof angle 30 ensures effective mining with sufficient service life under chiseling and abrasive conditions.

[0021] The secondary chisel edges 27 are opposite the primary chisel edges 13 in the direction of rotation 5 The secondary chisel edges 27 begin at the distal end19 of the arm 15. The chisel edges 27 begin adjacent to the guide surface 26. Their radial dimension is less than the radial dimension of the primary chisel edges 13. Preferably, the secondary chisel edges end 27 at the proximal end 18 the poor 15. The secondary chisel edges 27 are consistently less high along the radial direction than the primary chisel edges 13, ie is any radial distance to the axis of rotation 6 is the primary chisel edge 13 higher than the secondary chisel edge 27.

[0022] The secondary chisel edge 27 lies on the same arm 15 like the primary chisel edge 13. A distance 31 between the primary chisel edge 13 and the secondary chisel edge 13can be used almost over the entire length or at least a large part of the secondary chisel edge 27 be constant. The secondary chisel edge 27 runs largely parallel to the primary chisel edge 13 the same arm 15. The distance 31 is less than 1 / 4 of the diameter 20, e.g. less than 1 / 6 of the diameter 20, preferably larger than 1 / 8 of the diameter 20. The distance 31 is in particular smaller than the diameter of the hull 14.

[0023] The secondary chisel edge 27 runs through local height maxima along a radial direction. The secondary chisel edge 27 can move towards the top 12 continuously increase. The secondary chisel edge 27 is equal to the primary chisel edge 13 through the intersection line of a leading surface 32 and a trailing surface 33formed. The leading surface 32 rises against the direction of rotation 5 in direction of impact 8 the trailing surface 33 falls against the direction of rotation 5 in direction of impact 8 A roof angle between the two surfaces 32, 33 is greater than 45 degrees, preferably greater than 60 degrees and less than 120 degrees.

[0024] Between the primary chisel edge 13 and the secondary chisel edge 13 is a gutter 34 formed. The gutter 34 is through the open space 29 and the leading surface 32 enclosed. The gutter 34 begins at the distal end 19 and preferably extends to the proximal end 18 of the arm 15. A length of the gutter 34 is equal to the length of the secondary chisel edge 27. The gutter 34 runs on the arm 15and is therefore opposite to the direction of impact 8 closed.

[0025] The primary chisel edges 13 can be compared to the secondary chisel edges 27 inclined. An angle 35 between the primary chisel edge 13 and the secondary chisel edge 27 is low and preferably less than 8 degrees, e.g. less than 5 degrees ( Fig. 5 ). The planes of the two chisel edges 13, 27 cut off the arm 15 seen from behind the axis of rotation 6. The drill head 2 may have a four-fold rotational symmetry. In alternative embodiments, the diametrically opposed arms 15 identically formed and different from the neighboring arms 15. For example, a pair of arms 15 a shorter length than the other pair of arms 15. Furthermore, two of the arms 15 each with a primary chisel edge13 and a secondary chisel edge 27 and the other two arms 15 only with a primary chisel edge 36 be provided Fig. 7 .

[0026] The drill head 2 is preferably made of a sintered material, especially tungsten carbide. The drill head 2 is preferably monolithic, ie the arms 15 and the hull 14 are connected to each other without a joining zone, in particular without a weld seam, solder seam or screw connection.

[0027] The spiral 3 of the drill 1 For example, it has four spiral webs 37. The number of spiral webs 37 is preferably equal to the number of arms 15. The spiral walkways 37 run along the axis of rotation 6 several times around this axis of rotation 6 around. The spiral bridges 37 describe when turning the drill 1a cylindrical envelope whose diameter corresponds to a helix diameter. Adjacent helix webs 37 close a spiral groove between them 38 which is considered to be geometrically limited in the radial direction by the envelope. The drilling material is distributed in the helical grooves 38 through the spiral bridges 37 along the axis of rotation 6 transported. A spiral incline 39 is preferably in the range between 35 degrees and 60 degrees, e.g. 45 degrees.

[0028] The exemplary insertion end 4 of the drill 1 is designed for use with hand tools with turning tools. The shank 4 has an essentially cylindrical shape. The insertion end 4 has two closed locking grooves 40, in which locking elements of the hand tool engage radially and along the axis of rotation 6 can slide. To the axis of rotation6 longitudinally aligned grooves 41 enable torque to be applied from the hand tool.

Claims

1. Drilling head (2) for a drill bit (1) having a top side (9) for breaking down mineral material, a bottom side (10) for fastening to a shaft (3) of the drill bit (1), an axis of rotation (6), which runs centrally through the top side (9) and the bottom side (10), arms (15), which each have a proximal end (18) with respect to the axis of rotation (6) and a distal end (19) with respect to the axis of rotation (6), and wherein the top sides (9) of the arms (15) have primary chisel edges (13) each running from the proximal end (18) to the distal end (19), wherein at least one of the arms (15) on the top side (9) has a secondary chisel edge (27) running alongside the primary chisel edge (13), wherein the secondary chisel edge (27) is offset from the primary chisel edge (13) of the same arm (15) towards the front in a rotational direction (5) of the drilling head (2), characterized in that the primary chisel edge (13) and the secondary chisel edge (27) between them delimit a channel (34) on the top side (9) of the arm (15), and in that the primary chisel edge (13) continuously protrudes beyond the second chisel edge (27) of the same arm (15) in the impact direction (8).

2. Drilling head (2) according to Claim 1, characterized in that the primary chisel edge (13) and the secondary chisel edge (27) of the same arm (15) start at the distal end (19) of the arm (15).

3. Drilling head (2) according to either of the preceding claims, characterized in that the primary chisel edge (13) runs parallel to the secondary chisel edge (27) of the same arm (15).

4. Drilling head (2) according to one of the preceding claims, characterized in that the primary chisel edge (13) ends at a tip (12) of the drilling head (2) and the secondary chisel edge (27) ends in front of the tip (12).

5. Drilling head (2) according to one of the preceding claims, characterized in that a respective discharge opening (16) for discharging drilled material is arranged between adjacent arms (15) in the rotational direction (5).

6. Drilling head (2) according to one of the preceding claims, characterized in that an angle (35) between the primary chisel edge (13) and the secondary chisel edge (27) of the same arm (15) is less than 8 degrees.

7. Drilling head (2) according to one of the preceding claims, characterized in that the drilling head (2) has at least four arms (15).

8. Drilling head (2) according to one of the preceding claims, characterized in that the drilling head (2) is subdivided into a body (14) and the arms (15), wherein the body (14) denotes the largest cylinder that is able to be inscribed, in a coaxial arrangement with the axis of rotation (6), completely in the drilling head (2).

9. Drill bit (1) comprising a drilling head (2) according to one of the preceding claims, a shaft (3) welded or soldered to the bottom side (10) of the drilling head (2), and a shank (4) with a closed locking groove.