Hammer drill tool and hard material insert for a hammer drill tool

Abstract

Hammer drill tool (1) comprising a shank (2) and a hard material insert (3), wherein the hard material insert (3) has first and second parallel side surfaces (3a, 3b) and projects beyond the shank (2) with a head section (4) in the direction of action (x) of the hammer drill tool (1), wherein the hard material insert (3) is designed as a cutting plate (5), wherein the cutting plate (5) is widened laterally on both sides in the region of the longitudinal axis (L) of the hammer drill tool (1) with a first and second bulge (8, 9) in a half-barrel shape, wherein a radially oriented and outwardly sloping first and second secondary cutting edge (12, 13) is formed on the first and second cover surfaces (10, 11) of the first and second bulges (8, 9) facing in the direction of action (x) of the hammer drill tool (1), wherein a main cutting edge (22) of the cutting plate (5) in Direction of action (x) of the hammer drill tool (1) considered in a first area (22-1),which comprises a maximum of 30% of its length (L22) measured orthogonally to the longitudinal axis (L), runs in front of the first and second secondary cutting edges (12, 13),- wherein the first and second rake faces (12a, 13a) and the first and second clearance faces (12b, 13b) form the first and second cover faces (10, 11) and- wherein the first and second rake faces (12a, 13a) and the first and second clearance faces (12b, 13b) together with the first and second secondary cutting edges (12, 13) form a first and second wedge (16, 17), characterized in that a first and second cylindrical surface (14, 15) of the first and second bulge (8, 9) extends in relation to the direction of action (x) below the first and second secondary cutting edges (12, 13) in the region of the head section (4) into the first and second rake faces (12a, 13a) and the first and second free area (12b, 13b) of the first and second secondary cutting edge (12, 13) transitions.

Description

The invention relates to a hammer drill tool and a hard material insert for a hammer drill tool according to the preamble of claim 1 and claim 10, respectively. From US 5 287 937 A, a hammer drill tool is known which comprises a shank and a hard material insert, wherein the hard material insert has parallel side surfaces and projects beyond the shank with a head section in the direction of action of the hammer drill tool, wherein the hard material insert is designed as a cutting plate and wherein the cutting plate is widened laterally on both sides in the area of ​​a longitudinal axis of the hammer drill tool with a bulge in a half-barrel shape. Furthermore, DE 100 53 344 A1 discloses a rock drill with at least two essentially plate-shaped hard material inserts which are fastened in at least one radially extending groove in a tool head which has a recess within the groove, wherein the hard material inserts each have at least one radially projecting, curved segment which engages in the recess in the tool head. From US Patent 5,779,403 A, a rotary impact spiral drill is known with a shank having at least one main removal groove for drill cuttings extending spirally in its surface, and at least one carbide cutting edge formed on a one-piece cutting insert, the base of which is substantially fixed in a continuous groove extending over the diameter of the shank in an end face of the shank, wherein the base of the cutting insert is reinforced in the region of its diameter, preferably in the central region of its longitudinal extent, such that its cross-section has at least one substantially semicircular bulge, and the continuous groove in the end face of the shank has a recess formed corresponding to the reinforcement of the cutting insert, so that the base of the cutting insert is centered by positive locking. The invention is based on the objective of developing a hammer drill tool or a hard material insert for a hammer drill tool, in which the service life when hammer drilling reinforced concrete is increased. This problem is solved by starting with the features of the preamble of claim 1 or claim 10 and by the characterizing features of claim 1 or claim 10, respectively. Advantageous and expedient embodiments are specified in the respective dependent claims. In the impact tool according to the invention, a radially oriented and outwardly sloping secondary cutting edge is formed on the cover surfaces of the protrusions, which point in the direction of action of the hammer drill tool. A cylindrical surface of each protrusion below the secondary cutting edge transitions in the head section into a rake face and a clearance face of the secondary cutting edge. The rake face and the clearance face form the cover surface, and together with the secondary cutting edge, they form a wedge. Tests have shown that impact tools designed in this way have a significantly longer service life when drilling through reinforcing bars than conventional hammer drill tools with cutting inserts.This can be explained in particular by the fact that the secondary cutting edges act as wedges, especially when they hit a reinforcing bar, which dig into the reinforcing steel and peel off the burrs thrown up by the impact, so that the work of the main cutting edge in the area near the center or longitudinal axis of the cutting plate is considerably supported. The rake face and the clearance face are designed to be aligned at approximately equal angles to a plane defined by the secondary cutting edge and the longitudinal axis, and in particular, to be mirror-symmetrical to this plane. This ensures that the rake face and the clearance face are subjected to comparable stresses with each hammer blow, resulting in uniform wear and ensuring that the wedge effect is maintained for a long time. Furthermore, the shank is designed with a slot-like recess in which the cutting insert is received by a base section. This allows for cost-effective production of the hammer drill tool by simply soldering the cutting insert into the recess of the shank. Additionally, the base section of the cutting insert is protected and guided by the shank, so that any torsional forces occurring between the shank and the cutting insert are transferred via a positive fit between the shank and the cutting insert, thus minimizing stress on the soldered joint. It is provided that a leading and a trailing radial cutting edge are formed at the transition between the rake face and the clearance face into the cylindrical surface, with the radial cutting edges exhibiting a radial wedge angle of less than 120° at every point. Such sharp and stable radial cutting edges are suitable for performing both chiseling and abrasive / peeling functions with low wear. It is also designed so that the wedge-forming rake face and the wedge-forming clearance face form a wedge angle of a maximum of 90° and a minimum of 50° at every point on the secondary cutting edge. This gives the wedge high stability and therefore a good service life with regard to operating conditions in which it is driven into reinforced concrete like a chisel. Regarding the rake face and the clearance face, the rake face can be designed as either a flat or a concave surface, and the clearance face as either a flat or a convex surface. The resulting combinations of these features make the hammer drill bit, when designed with flat surfaces, a particularly versatile tool with a long service life. A concave rake face effectively sharpens the wedge, allowing it to penetrate the reinforcement more easily and remove material more readily. A convex clearance face increases the breaking performance, thus facilitating hammer drilling in areas free of reinforcement. To avoid excessive stress on the secondary cutting edges, it is intended that the secondary cutting edges are aligned radially and axially spaced from a tip of the cutting plate, so that they are set back from the tip in the direction of action of the hammer drill tool. It is also planned to form the cylindrical surfaces of the protrusions with the contour of an ellipse in cuts made perpendicular to the longitudinal axis of the hammer drill tool, with one long axis of the ellipse lying in the cutting plane and oriented approximately parallel to the side surfaces of the cutting insert. This prevents excessive weakening of the shank of the impact tool without compromising the half-barrel shape of the protrusion. According to the invention, it is further provided that a main cutting edge of the cutting plate, viewed in the direction of action of the hammer drill tool, runs in front of the secondary cutting edge in a first area which comprises a maximum of 30% of its length measured orthogonally to the longitudinal axis. It is also provided that a main cutting edge of the cutting insert runs behind the secondary cutting edge in a second, two-part section, comprising at least 20% and at most 50% of its length measured orthogonally to the longitudinal axis, and / or runs within the area of ​​the secondary cutting edge in a third, two-part section, comprising at least 20% and at most 40% of its length measured orthogonally to the longitudinal axis. This ensures that the secondary cutting edges contribute significantly to the work process both when drilling without contact with a reinforcing bar and when drilling with contact with a reinforcing bar, thus relieving or supporting the main cutting edge. Finally, the hammer drill tool is designed to have its shank equipped with at least two, and in particular four, helical threads, with the first helical thread terminating at the first bulge and the second helical thread terminating at the second bulge. This ensures that even in the area of ​​the secondary cutting edges, drill cuttings can be carried away unhindered by the webs that define the helical threads. In the hard material insert according to the invention, a radially oriented and outwardly sloping secondary cutting edge is formed on the end surfaces of the protrusions facing in the direction of action. A cylindrical surface of each protrusion below the secondary cutting edge transitions into a rake face and a clearance face of the secondary cutting edge in the region of a head section of the hard material insert. The rake face and the clearance face form the end surface. The rake face and the clearance face are oriented symmetrically to a plane defined by the secondary cutting edge and the longitudinal axis. Together with the secondary cutting edge, the rake face and the clearance face form a wedge. Tests have shown that hard material inserts designed in this way exhibit a significantly longer service life when drilling through reinforcing bars than conventional hard material inserts.This can be explained in particular by the fact that the secondary cutting edges act as wedges, especially when they hit a reinforcing bar, which dig into the reinforcing steel and peel off the burrs thrown up by the impact, so that the work of the main cutting edge in the area near the center or longitudinal axis of the cutting plate is considerably supported. It is designed that the rake face and the clearance face are aligned at approximately equal angles to a plane defined by the secondary cutting edge and the longitudinal axis, and in particular, that they are mirror-symmetrical to this plane. This ensures that the rake face and the clearance face are subjected to comparable stresses with each hammer blow, resulting in uniform wear and thus ensuring that the wedge effect is maintained for a long time. Furthermore, it is provided that a leading and a trailing radial cutting edge are formed at the transition between the rake face and the clearance face into the cylindrical surface, with the radial cutting edges exhibiting a radial wedge angle of less than 120° at every point. Such sharp and stable radial cutting edges are suitable for performing both chiseling and abrasive / peeling functions with minimal wear. It is also designed so that the wedge-forming rake face and the wedge-forming clearance face form a wedge angle of a maximum of 90° and a minimum of 50° at every point on the secondary cutting edge. This gives the wedge high stability and therefore a good service life with regard to operating conditions in which it is driven into reinforced concrete like a chisel. Regarding the rake face and the clearance face, the rake face can be designed as either a flat or a concave surface, and the clearance face as either a flat or a convex surface. The resulting combination possibilities make the cutting insert, when designed with flat surfaces, a particularly versatile cutting insert with a long tool life. A concave rake face effectively sharpens the wedge, allowing it to penetrate the reinforcement more easily and remove material more readily. A convex clearance face increases the crushing performance, thus facilitating drilling in areas free of reinforcement. To avoid excessive stress on the secondary cutting edges, it is intended that the secondary cutting edges are aligned radially and axially spaced from a tip of the cutting plate, so that they are set back from the tip in the direction of action of the hard material insert. It is also planned to form the cylindrical surfaces of the protrusions with an elliptical contour in cuts made perpendicular to the longitudinal axis of the hammer drill tool, with one long axis of the ellipse lying in the cutting plane and oriented approximately parallel to the side surfaces of the cutting insert. This prevents excessive weakening of the shank receiving the hard material insert by a slot-like depression, without having to forgo a half-barrel-shaped protrusion. According to the invention, it is further provided that a main cutting edge of the cutting plate, viewed in the direction of action of the hammer drill tool, runs in front of the secondary cutting edge in a first area which comprises a maximum of 30% of its length measured orthogonally to the longitudinal axis. It is also provided that a main cutting edge of the cutting insert runs behind the secondary cutting edge in a second, two-part section, comprising at least 20% and at most 50% of its length measured orthogonally to the longitudinal axis, and / or runs within the area of ​​the secondary cutting edge in a third, two-part section, comprising at least 20% and at most 40% of its length measured orthogonally to the longitudinal axis. This ensures that the secondary cutting edges contribute significantly to the work process both when drilling without contact with a reinforcing bar and when drilling with contact with a reinforcing bar, thus relieving or supporting the main cutting edge. For the purposes of the invention, a hard material insert is understood to be, in particular, a cutting plate made of carbide or a comparable material. Further details of the invention are described in the drawing with reference to schematically illustrated embodiments. Figure 1 shows a side view of a hammer drill tool according to the invention with a hard material insert according to the invention; Figure 2 shows a top view of the hard material insert shown in Figure 1; Figure 3 shows a rear view of the hard material insert shown in Figure 1; Figure 4 shows a right-side view of the hard material insert shown in Figure 1; Figure 5 shows a left-side view of the hard material insert shown in Figure 1; and Figure 6 shows a bottom view of the hard material insert shown in Figure 1. Figure 1 shows a side view of a hammer drill tool 1 according to the invention. The hammer drill tool 1 comprises a shank 2 and a hard material insert 3. The hard material insert 3 has parallel side surfaces 3a, 3b and projects beyond the shank 2 in the direction of action x of the hammer drill tool 1 with a head section 4. The hard material insert 3 is designed as a cutting plate 5. To receive the hard material insert 3 or the cutting plate 5, the shank 2 includes a slot-like recess 6 in which the cutting plate 5 is received with a base section 7. The cutting plate 5 is widened laterally on both sides in the region of a longitudinal axis L of the hammer drill tool 1 by means of a half-barrel-shaped projection 8, 9 (see also Figure 2). On the cover surface 10, 11 of the protrusions 8 and 9, which point in the direction of action x of the hammer drill tool 1, a radially oriented and outwardly sloping secondary cutting edge 12, 13 is formed in each case.Here, a cylindrical surface 14, 15 of each protrusion 8, 9 below the respective secondary cutting edge 12, 13 in the region of the head section 4 transitions into a rake face 12a or 13a and a clearance face 12b or 13b of the secondary cutting edge 12 or 13. The rake face 12a and the clearance face 12b form the top surface 12, and the rake face 13a and the clearance face 13b form the top surface 13. The rake face 12a or 12b and the clearance face 13a or 13b are each oriented symmetrically to a plane E-L13 (see Fig. 3) defined by the secondary cutting edge 12 or 13 and the longitudinal axis L. The rake face 12a and the clearance face 12b together with the secondary cutting edge 12 form a wedge 16. The rake face 13a and the clearance face 13b together with the secondary cutting edge 13 form a wedge 17. The shank 2 is shown schematically in Fig. 1 with dashed lines as a transparent component, with the hard material insert 2 or 13b being visible.The cutting insert 5 is received in the base section 7 of the slot-like recess 6 of the shaft 3. In an end area not shown, the shaft 2 has a clamping end with which it can be clamped into a chuck of a hammer drill. Particularly evident from the side views shown in Figs. 1 and 3 is that at the transition between the rake face 12a or 13a and the clearance face 12b or 13b into the cylindrical surface 14 or 15, a leading radial cutting edge 18 or 19 and a trailing radial cutting edge 20 or 21 are formed. The radial cutting edges 18 to 21 each have a radial wedge angle RKW, which is shown schematically and by way of example for the radial cutting edge 21 in Fig. 3, and where the radial wedge angle RKW is less than 120°. Figure 3 further shows that the rake face 13a and the clearance face 13b forming the wedge 17 form a wedge angle KW of a maximum of 90° and a minimum of 50° at every point of the secondary cutting edge 13. The secondary cutting edge 12 and its rake face 12a and clearance face 12b are designed comparably. In the cutting insert 5 of the hammer drill tool 1, which is shown in Figs. 1, 2, 3, 4, 5 to 6, the clamping surfaces 12a, 13a and the clearance surfaces 12b, 13b are each designed as flat surfaces. According to embodiment variants not shown, it is provided that, contrary to this, at least one of the clamping surfaces 12a, 13a is designed as a concave surface and / or at least one of the clearance surfaces 12b, 13b as a convex surface. Furthermore, the rake face 12a or 13a and the clearance face 12b or 13b are aligned at approximately equal angles W13a and W13b to the plane E-L12 or E-L13 defined by the secondary cutting edge 12 or 13 and the longitudinal axis L, respectively, to form the wedge 16 or 17 (to keep the figures as clear as possible, no angles are shown in Fig. 1). As shown in Fig. 3 and already explained above, in the exemplary embodiment, the rake face 13a and the clearance face 13b are aligned symmetrically to the plane E-L13. As can be seen particularly from a comparison of Figs. 2, 4, and 5, the two secondary cutting edges 12, 13 are spaced radially and axially from a tip S5 of the cutting insert 5. The secondary cutting edge 12 has a radial distance RA12 from the tip S5 (see Fig. 2) and an axial distance AA12 from the tip S5 (see Fig. 4). Corresponding distances result for the secondary cutting edge 13, since the two secondary cutting edges 12, 13 are arranged symmetrically about the longitudinal axis L (see Fig. 1) which passes through the tip S5. From the top view of the cutting plate 5 shown in Fig. 2 and from the bottom view of the cutting plate 5 shown in Fig. 6, it can be seen that the cylindrical outer surfaces 14, 15 of the protrusions 8, 9 in sections carried out perpendicular to the longitudinal axis L of the hammer drill tool 1 or the cutting plate 5 each have the contour of an ellipse EL14 or EL15, wherein a long axis of the ellipse LEA14 or LEA15 of the ellipse EL14 or EL15 lies in the plane of the section and is oriented approximately parallel to the side surfaces 3a, 3b of the cutting plate 5. As can be seen from the top view shown in Fig. 2, a main cutting edge 22 runs approximately diagonally across the cutting insert 5, with the main cutting edge 22 passing through the tip S5 without forming a cross-cutting edge. In the side view (see, for example, Fig. 3) of the cutting insert 5, the main cutting edge 22 forms a contour line. The secondary cutting edges 12, 13 also form contour lines, which are oriented perpendicular to the contour line of the main cutting edge 22. A comparative analysis of these contour lines reveals that the main cutting edge 22 of the cutting plate 5, viewed in the direction of action x of the hammer drill tool 1, runs in a first area 22-1, which comprises a maximum of 30% of its length L22 measured orthogonally to the longitudinal axis L or in plan view, in front of the secondary cutting edge 12 or 13, and / or in a second, two-part area 22-2, which comprises at least 20% and a maximum of 50% of its length L22 measured orthogonally to the longitudinal axis L or in plan view.the length L22 measured in plan view extends behind the secondary cutting edge 12, 13 and / or in a third, two-part area 22-3, which comprises at least 20% and at most 40% of its length orthogonal to the longitudinal axis L or L22 measured in plan view, in the area of ​​the secondary cutting edge 12, 13. Fig. 2 additionally shows a direction of rotation w of the cutting insert 5. The main cutting edge 22, which extends over a right wing 23 and a left wing 24 of the cutting insert 5, has on its wings 23, 24 a main cutting chip surface 25a and 26a respectively, and a main cutting clearance surface 25b and 26b respectively. The shaft 2 of the hammer drill tool 1 comprises - as shown in Fig. 1 - two helical turns 27, 28, wherein the first helical turn 27 terminates at the first bulge 8 and wherein the second helical turn 28, which is hidden in the illustration, terminates at the second bulge 9. According to an embodiment not shown, it is also possible to equip the shank of the hammer drill tool with more than two helical threads, and in particular with four helical threads. In this case, it is provided that each helical thread terminates towards a clamping surface, so that one helical thread is assigned to each of the clamping surfaces of the secondary cutting edges and one to each of the clamping surfaces of the main cutting edge. Reference symbol list: 1 Hammer drill tool 2 Shank 3 Hard material insert 3a, 3b Parallel side surface 4 Head section 5 Cutting plate 6 Slot-like recess in 2 7 Foot section of 3 or 5 8, 9 Bulge at 3 or 5 10, 11 Cover surface of 8 or 9 12 Secondary cutting edge 12a Rake surface of 12 12b Clearance surface of 12 13 Secondary cutting edge 13a Rake surface of 13 13b Clearance surface of 13 14, 15 Cylindrical surface 16 Wedge at 8 17 Wedge at 9 18 Leading radial cutting edge at 14 19 Leading radial cutting edge at 15 20 Trailing radial cutting edge at 14 21 Trailing radial cutting edge at 15 22 Main cutting edge 22-1 First section of L22 22-2 Second, two-part section of L22 22-3 third,two-part area of ​​L22 23 right wing of 5 24 left wing of 5 25a main cutting edge chip surface of 22 25b main cutting edge clearance surface of 22 26a main cutting edge chip surface of 22 26b main cutting edge clearance surface of 22 27 helix of 2 28 helix of 2 AA12 axial distance between 12 and 5 E-L12 plane defined by L and 12 E-L13 plane defined by L and 13 EL14 ellipse EL15 ellipse KW wedge angle at 13 L longitudinal axis L22 length of 22 LEA14 long ellipse axis of EL14 LEA15 long ellipse axis of EL15 RA12 radial distance between 12 and 5 RKW radial wedge angle S5 tip of 5 W13a angle between E-L13 and 13a W13b angle between E-L13 and 13b w Direction of rotation of 5 x direction of action,

Claims

Hammer drill tool (1) comprising a shank (2) and a hard material insert (3), wherein the hard material insert (3) has first and second parallel side surfaces (3a, 3b) and projects beyond the shank (2) with a head section (4) in the direction of action (x) of the hammer drill tool (1), wherein the hard material insert (3) is designed as a cutting plate (5), wherein the cutting plate (5) is widened laterally on both sides in the region of the longitudinal axis (L) of the hammer drill tool (1) with a first and second bulge (8, 9) in a half-barrel shape, wherein a radially oriented and outwardly sloping first and second secondary cutting edge (12, 13) is formed on the first and second cover surfaces (10, 11) of the first and second bulges (8, 9) facing in the direction of action (x) of the hammer drill tool (1), wherein a main cutting edge (22) of the cutting plate (5) in Direction of action (x) of the hammer drill tool (1) considered in a first area (22-1),which comprises a maximum of 30% of its length (L22) measured orthogonally to the longitudinal axis (L), runs in front of the first and second secondary cutting edges (12, 13),- wherein the first and second rake faces (12a, 13a) and the first and second clearance faces (12b, 13b) form the first and second cover faces (10, 11) and- wherein the first and second rake faces (12a, 13a) and the first and second clearance faces (12b, 13b) together with the first and second secondary cutting edges (12, 13) form a first and second wedge (16, 17), characterized in that a first and second cylindrical surface (14, 15) of the first and second bulge (8, 9) extends in relation to the direction of action (x) below the first and second secondary cutting edges (12, 13) in the region of the head section (4) into the first and second rake faces (12a, 13a) and the first and second free area (12b, 13b) of the first and second secondary cutting edge (12, 13) transitions. Hammer drill tool (1) according to claim 1 , characterized in that the first and second rake face (12a, 13a) and the first and second clearance face (12b, 13b) are aligned at approximately equal angles to a plane (E-L13) defined by the first and second secondary cutting edge (12, 13) and the longitudinal axis (L) and are in particular aligned in a mirror-symmetrical manner to this plane (E-L13). Hammer drill tool (1) according to claim 1, characterized in that the shaft (2) comprises a slot-like recess (6) and that the cutting plate (5) is received in the slot-like recess (6) with a foot section (7). Hammer drill tool (1) according to at least one of the preceding claims, characterized in that at the transition of the first and second rake face (12a, 13a) and the first and second clearance face (12b, 13b) into the first and second cylindrical surface (14, 15) a leading first and second radial cutting edge (18, 19) and a trailing first and second radial cutting edge (20, 21) are formed, wherein the first and second radial cutting edges (18 - 21) have a radial wedge angle (RCA) at each point which is less than 120°. Hammer drill tool (1) according to at least one of the preceding claims, characterized in that the first and second rake surfaces (12a, 13a) forming the first and second wedge (16, 17) and the first and second clearance surfaces (12b, 13b) form a wedge angle (KW) of a maximum of 90° and a minimum of 50° at each point of the first and second secondary cutting edges (12, 13). Hammer drill tool (1) according to claim 1, characterized in that the first and second rake surface (12a, 13a) is designed as a flat surface or as a concave curved surface and that the first and second clearance surface (12b, 13b) is designed as a flat surface or as a convex curved surface. Hammer drill tool (1) according to at least one of the preceding claims, characterized in that the first and second secondary cutting edge (12, 13) to a tip (S5) of the cutting plate (5) each have a radial distance (RA12) and an axial distance (AA12). Hammer drill tool (1) according to at least one of the preceding claims, characterized in that the first and second cylindrical surfaces (14, 15) of the first and second protrusions (8, 9) in cuts made perpendicular to the longitudinal axis (L) of the hammer drill tool (1) each have the contour of a first and second ellipse (EL14, EL15), wherein a long first and second ellipse axis (ELA14, ELA15) of the first and second ellipse (EL14, EL15) lies in the cutting plane and is oriented approximately parallel to the first and second side surfaces (3a, 3b) of the cutting plate (5). Hammer drill tool (1) according to at least one of the preceding claims, characterized in that a main cutting edge (22) of the cutting plate (5) in the direction of action (x) of the hammer drill tool (1) extends in a second, two-part area (22-2), which comprises at least 20% and at most 50% of its length (L22) measured orthogonally to the longitudinal axis (L), behind the first and second secondary cutting edge (12, 13) and / or in a third, two-part area (22-3), which comprises at least 20% and at most 40% of its length (L22) measured orthogonally to the longitudinal axis (L), in the area of ​​the first and second secondary cutting edge (12, 13). Hard material insert (3) for a hammer drill tool (1) comprising a hard material insert (3),- wherein the hard material insert (3) has parallel first and second side surfaces (3a, 3b),- wherein the hard material insert (3) is designed as a cutting plate (5),- wherein the cutting plate (5) is laterally widened on both sides in the region of a longitudinal axis (L) with a first and second bulge (8, 9) in a half-barrel shape,- wherein a radially oriented and outwardly sloping first and second secondary cutting edge (12, 13) is formed on the first and second cover surfaces (10, 11) of the first and second bulges (8, 9) pointing in the direction of action (x),- wherein a main cutting edge (22) of the cutting plate (5) is located in a first region (22-1) which is at most 30% of its length (L22) measured orthogonally to the longitudinal axis (L) includes, runs in front of the first and second secondary cutting edges (12, 13),- wherein the first and second rake faces (12a, 13a) and the first and second clearance faces (12b, 13b) form the first and second cover faces (10, 11) and- wherein the first and second rake faces (12a, 13a) and the first and second clearance faces (12b, 13b) together with the first and second secondary cutting edges (12, 13) form a first and second wedge (16, 17), characterized in that a first and second cylindrical surface (14, 15) of each first and second protrusion (8, 9) in respect of an effective direction (x) below the first and second secondary cutting edges (12, 13) in the region of a head section (4) of the cutting insert (5) extends into a first and second rake face (12a, 13a) and a first and second clearance face (12b, 13b) of the first and second secondary cutting edges (12, 13) transitions. Hard material insert (3) according to claim 10, characterized in that the first and second chip surface (12a, 13a) and the first and second clearance surface (12b, 13b) are aligned at approximately equal first and second angles (W13a, W13b) to a first and second plane (E-L12, E-L13) defined by the first and second secondary cutting edge (12, 13) and the longitudinal axis (L) and are in particular oriented in a mirror-symmetrical manner to this first and second plane (E-L12, E-L13). Hard material insert (3) according to claim 10, characterized in that at the transition of the first and second rake face (12a, 13a) and the first and second clearance face (12b, 13b) into the first and second cylindrical surface (14, 15) a leading first and second radial cutting edge (18, 19) and a first and second trailing radial cutting edge (20, 21) are formed, wherein the first and second radial cutting edges (18 - 21) have a radial wedge angle (RCA) at each point which is less than 120°. Hard material insert (3) according to at least one of claims 10 to 12, characterized in that the first and second rake face (12a, 13a) forming the first and second wedge (16, 17) and the first and second clearance face (12b, 13b) forming the first and second (16, 17) wedge form a wedge angle (KW) of a maximum of 90° and a minimum of 50° at each point of the first and second secondary cutting edge (11, 12). Hard material insert (3) according to at least one of claims 10 to 13, characterized in that the first and second chip surface (12a, 13a) is designed as a flat surface or as a concave curved surface and that the first and second clearance surface (12b, 13b) is designed as a flat surface or as a convex curved surface. Hard material insert (3) according to at least one of claims 10 to 14, characterized in that the first and second secondary cutting edge (12, 13) to a tip (S5) of the cutting plate (S5) each have a radial distance (RA12) and an axial distance (AA12). Hard material insert (3) according to at least one of claims 10 to 15, characterized in that the first and second cylindrical surfaces (14, 15) of the first and second protrusions (8, 9) in cuts made perpendicular to the longitudinal axis (L) of the hammer drill tool (1) each have the contour of a first and second ellipse (EL14, EL15), wherein a first and second long ellipse axis (ELA14, ELA15) of the first and second ellipse (EL14, EL15) lies in the cutting plane and is oriented approximately parallel to the first and second side surfaces (3a, 3b) of the cutting plate (5). Hard material insert (3) according to at least one of claims 10 to 16, characterized in that a main cutting edge (22) of the cutting plate (5) in the direction of action (x) of the hammer drill tool (1) extends in a second, two-part area (22-2), which comprises at least 20% and at most 50% of its length (L22) measured orthogonally to the longitudinal axis (L), behind the first and second secondary cutting edge (12, 13) and / or in a third, two-part area (22-3), which comprises at least 20% and at most 40% of its length (L22) measured orthogonally to the longitudinal axis (L), in the area of ​​the first and second secondary cutting edge (12, 13).

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