Soil-working tool for a driven soil-working machine

Abstract

The invention relates to a soil-working tool (10) for a soil-working machine, in particular rotary harrows, rotary cultivators, rotor harrows, rotary tillers, tine rotors or the like, comprising a tine-like working section (11) and a fastening section (14), wherein: the working section (11) has a cutting region (12); in the cutting region (12), a fastening groove (40) is provided which extends between the free end of the working section (11) and the fastening section (14) in the region of a front working edge (18) at least in parts; a cutting edge (20) is fastened in the cutting region (12); the cutting edge (20) has a terminating piece (30) made of a hard material, in particular made of tungsten carbide material or ceramic material; the terminating piece (30) is at least partly disposed in the region of the groove end of the fastening groove (40) that is nearest the fastening section (14), and a connection section (33) of the terminating piece is fastened in the fastening groove (40); the fastening groove (40) has a groove base (47) and, laterally adjacent thereto, two groove side walls (41, 42) which extend in the groove longitudinal direction. For improved service life and functionality of such a soil-working tool (10), according to the invention the fastening groove (40), at its end nearest the fastening section (14), tapers off continuously in a groove taper (46) toward the working edge (18) and the terminating piece (30) covers the groove taper (46) at least in parts.

Description

[0001] Soil cultivation tool for a powered soil cultivation machine

[0002] The invention relates to a soil cultivation tool for a driven soil cultivation machine, e.g., rotary harrow, rotary cultivator, rotary tiller, rotary tiller, tine rotor, or similar, with a tine-shaped working section and a mounting section, wherein the working section, preferably in the region of its free end facing away from the mounting section, has a cutting area, wherein a mounting groove is provided in the cutting area, which extends at least partially between the free end of the working section and the mounting section in the region of a front working edge, wherein a cutting element is attached in the cutting area, and wherein the cutting element has an end piece consisting of a hard material, in particular tungsten carbide or ceramic material.wherein the end piece is at least partially arranged in the area of ​​the groove end of the fastening groove facing the fastening section and is fastened in the fastening groove with a connecting section, and wherein the fastening groove has a groove base and two groove side walls adjoining it laterally, which extend in the longitudinal direction of the groove.

[0003] According to the invention, the working section can preferably be formed in one piece. However, it is also conceivable that the working section can be formed in multiple parts. For example, the cutting element can be attached to a cutting holder, and this holder can be attached to a support of the working section.

[0004] According to the invention, the two groove side walls can be designed, at least in certain areas, as flat and / or curved surfaces. The groove side walls can form separate geometric elements or merge into one another, in particular by direct or indirect transition, for example, by merging seamlessly into one another.

[0005] From EP 3 244 717 B1, a soil cultivation tool in the form of a rotary harrow tine is known, which has a working section with a mounting groove. A multi-part cutting element is attached in the mounting groove. By means of a mounting section integrally molded onto the working section, the rotary harrow tine can be interchangeably attached to a rotary harrow.

[0006] The object of the invention is to provide a rotary harrow tine of the type mentioned above, which is characterized by improved operating behavior.

[0007] This task is solved by ensuring that the fastening groove at its end facing the fastening section tapers continuously towards the working edge by means of a groove run-out, and that the end piece covers the groove run-out at least partially.

[0008] The depth of the mounting groove decreases continuously towards the working edge as it extends from the groove's end. This creates a stress-optimized, preferably continuous, transition from the groove to the working edge at the groove's end, thus minimizing notch stresses. This significantly improves the load-bearing capacity of the tillage tool. According to the invention, the groove's end area is also at least partially covered by an end piece. This protects this area from abrasive damage caused by soil material. Furthermore, it prevents the accumulation of tillage material, such as soil or stalks, in the groove's end area, which could impair the tillage machine's performance and traction requirements. This significantly improves the tillage tool's performance according to the invention.

[0009] According to a preferred embodiment of the invention, the two groove side walls in the area of ​​the groove outlet each extend from the groove base towards the working edge in the form of a wall section, wherein the height of the groove side walls, measured in the direction of the groove depth at the groove outlet, decreases in the direction of the longitudinal extent of the fastening groove, preferably continuously, and the end piece covers the groove side walls at least partially in the groove outlet. Preferably, a material-bonded connection is formed between the groove side walls and the area facing the connecting section of the end piece, in particular by the use of solder material. This provides secure support for the end piece and thus reduces the risk of breakage.Therefore, it may be provided in particular that a gap area is formed between the connecting section and the groove exit of the fastening groove, which is at least partially filled with a material-bonding connecting material, in particular with solder material.

[0010] One possible embodiment of the invention is such that the gap area has a varying gap height in the direction of the longitudinal extension of the fastening groove, measured in the direction of the groove depth. Preferably, the gap area has two spaced-apart gap ends in the longitudinal direction of the fastening groove, and the gap area between the gap ends has a greater gap height than the gap area at the gap ends. For manufacturing, the end piece can be positioned correctly on contact areas of the fastening groove in the region of the gap ends. The end piece is then bonded to the fastening groove, with the bonding material, in particular solder, distributing itself in the gap area.

[0011] A preferred embodiment of the invention is such that the end piece forms a cutting element with a cutting edge on an outer surface facing away from the groove base. This improves the cutting performance, or allows the cutting element to be designed more compactly. Preferably, the cutting edge is formed by a convex surface, in particular by a partial cylindrical surface. This cutting edge geometry is particularly fracture-resistant. However, it can additionally or alternatively be provided that the cutting edge forms a cutting edge. Preferably, the cutting edge of the end piece can have the same geometry as one or more further cutting elements of the cutting element arranged in series.

[0012] One possible variant of the invention is such that the connecting section of the end piece has two lateral convex curvature sections arranged at an angle to each other, which are transitioned into one another in the area of ​​the groove base of the fastening groove.

[0013] Preferably, the two convex curved sections can be transitioned into each other by means of a bridge, wherein the bridge is particularly preferably designed in the form of a rounding that transitions the two curved sections into each other.

[0014] However, it can also be provided that the connecting section forms or has a convex geometry, preferably a continuous one, which forms the two lateral convex arch sections and the web between the arch sections.

[0015] In the variants described above, the bridge does not have to be designed as a pronounced protruding bridge, but can, for example, result as a geometric section that is integrated into the contour of the curved sections.

[0016] In the simplest case, the fastening section can, for example, have a cylindrical surface that forms the two curved sections.

[0017] A preferred embodiment of the invention is such that the end piece has a connecting surface at its longitudinal end facing the free end of the working section, to which an adjacent cutting element of the cutting assembly is arranged either without gaps or with a gap forming a spacer. Such a division of the cutting assembly into individual elements reduces the risk of breakage. Furthermore, a modular construction becomes possible, such that the end piece can be used in various configurations. In the area between the end piece and the arranged cutting element, material of a metallurgical bond, in particular solder material, is preferably held.

[0018] It is preferably also provided that a gap is formed between the arranged cutting element and the connecting surface of the end piece, and that the gap is bridged, at least partially, by means of at least one spacer, wherein it is preferably provided that the spacer is integrally formed with the end piece or the cutting element. The spacer ensures that the connecting surface is at least partially separated from the arranged cutting element. If the working area of ​​the soil cultivation tool deforms during operation, the spacer prevents the end piece from colliding with the arranged cutting element in such a way as to damage the brittle material of the end piece.

[0019] According to a further embodiment of the invention, the end piece may have an end section that projects beyond the groove runout of the mounting groove towards the free end of the working section. In other words, the end piece projects, for example, into a region of the mounting groove that extends in a straight line along its longitudinal extent. A further cutting element can then be precisely aligned here.

[0020] For a stable connection of the end piece, it can also be provided that the connecting section of the end piece extends into the area of ​​the end section, and that the end section is connected to the fastening groove via the connecting section, preferably by a material bond, in particular by soldering. The material bond also forms a mechanical buffer that can absorb impact loads.

[0021] A soil cultivation tool according to the invention can be characterized in that the connecting section of the end piece has two lateral positioning surfaces extending in the direction of the longitudinal extent of the fastening groove, preferably flat, concave or convex, which each bear directly or indirectly against a side wall of the groove. The positioning surfaces enable precise alignment of the end piece with the fastening groove.

[0022] A preferred embodiment of the invention is such that the end piece forms a front section at its longitudinal end facing the fastening section, which delimits the end piece and terminates in the area between the groove side walls in the region of the groove run-out. Thus, the front section can be designed to be sufficiently robust and stable, thereby reducing the risk of breakage of the end piece in this area.

[0023] The invention is explained in more detail below with reference to an exemplary embodiment illustrated in the drawings, using a rotary harrow tine as an example. The invention is comparably applicable to rotary cultivator tines, rotary harrow tines, milling blades, rotor tines, and similar implements. The drawings show:

[0024] Figure 1 shows a rotary harrow tine in a perspective side view from the outside,

[0025] Figure 2 shows the rotary harrow tine according to Figure 1 in a perspective side view from the inside,

[0026] Figure 3 shows the rotary harrow tines according to Figures 1 and 2 in a side view from the outside,

[0027] Figure 4 shows a side view of the end piece of the rotary harrow tine according to Figures 1-3.

[0028] Figure 5 shows the end piece according to Figure 4 in a view from below.

[0029] Figure 6 shows the end piece along the section marked Vl-Vl in Figure 5, Figure 7 shows the end piece along the section marked Vll-Vll in Figure 5,

[0030] Figure 8 shows the final piece according to Figures 4-7 in a perspective view from below.

[0031] Figure 9 shows the end piece according to Figures 4-8 in a front view,

[0032] Figure 10 shows the final piece according to Figures 4-9 in a perspective view from behind,

[0033] Figure 11 shows an enlarged detail view of the rotary harrow tine according to Figures 1-3,

[0034] Figure 12 shows the rotary harrow tines according to the cutting path marked X1-X1 in Figure 3,

[0035] Figure 13 shows the rotary harrow tines according to the cutting path marked X11-X11 in Figure 3,

[0036] Figure 14 shows the rotary harrow tines along the cutting path marked XIV-XIV in Figure 13 and

[0037] Figure 15 shows a manufacturing detail in schematic representation.

[0038] Figures 1 and 2 show a rotary harrow tine 10 for use on an agricultural rotary harrow. The rotary harrow tine 10 has a mounting section 14 to which a working section 11 is connected via a transition section 13. Preferably, the working section 11 is integrally connected to the mounting section 14 via the transition section 13. This component can be made from a sheet steel blank or, as in the present case, as a forging. If the component is made as a forging, it has improved strength. Furthermore, this simplifies the manufacturing process.

[0039] The fastening section 14 has at least one fastening receptacle 15, which may be in the form of a bore. In the present embodiment, two fastening receptacles 15 are arranged spaced apart from each other. The fastening section 14 may have two lateral bulges 15.1 into which the fastening receptacles 15 extend, preferably at least partially. This allows for a large support distance between the fastening receptacles 15 with less material.

[0040] During operation, the rotary harrow tine 10 is rotated along a circular path by the rotary harrow. This is indicated in Figure 1 by the rotation arrow “D”. Additionally, the rotary harrow tine 10 is pulled in the working direction by a tractor. Thus, the rotary harrow tine 10 performs a superimposed linear rotary motion.

[0041] The rotary harrow tine 10 has a radially outer outer surface 17 in the area of ​​the working section 11 and, opposite it, a radially inner inner surface 16. In the working direction at the front, the inner surface 16 transitions into the outer surface 17 via a working edge 18.

[0042] The working section 11 forms a cutting area 12 in the area of ​​the working edge 18. A cutting attachment 20 is arranged in the cutting area 12.

[0043] Preferably, the cutting element 20 is designed in multiple parts and comprises several cutting elements 22 arranged in a row. In the area of ​​the free end facing away from the fastening section 14, one of the cutting elements 22 forms a cutting end piece 21.

[0044] Opposite, the series of cutting elements is bounded by a cutting element 22, which forms an end piece 30. A fastening groove 40 is cut into the working edge 18 for securing the cutting elements 22. The fastening groove 40 extends in the direction of the longitudinal extent of the working edge 18.

[0045] Figures 11-13 show the arrangement and design of the fastening groove 40. As these illustrations demonstrate, the fastening groove 40 is bounded by two groove side walls 41, 42. The groove side walls 41, 42 extend in the direction of the longitudinal extent of the working edge 18, preferably substantially linearly in the direction of the longitudinal extent of the working edge 18.

[0046] As shown in the illustrations, the groove side walls 41, 42 may be formed essentially of planar wall sections. It is also conceivable that the groove side walls 41, 42 are formed of convex or concave wall sections extending in the direction of the longitudinal extent of the working edge 18. A combined geometry in which planar, convex and / or concave wall sections are combined is also conceivable.

[0047] The groove side walls 41, 42 may be spaced apart from each other in the area of ​​the groove base 47 or merge seamlessly into one another. It is also conceivable that the groove side walls 41, 42 merge continuously into one another in the groove base 47. In particular, it is conceivable that the groove side walls 41, 42 are formed by a concave recess that is incorporated into the working edge 18.

[0048] Preferably, however, as illustrated in the drawings, the groove side walls 41 , 42 are at least partially flat to allow for precise positioning of the cutting elements 22.

[0049] The groove side walls 41, 42 transition at their end facing the fastening section 14 via a groove outlet 46 into the working edge 18, as illustrated in Figure 11. The transition is designed such that the groove side walls 41, 42 preferably taper continuously, and in particular in a continuously differentiable manner, through the groove base 47 in the cross-section shown in Figure 11. The transition between the groove outlet 46 and the working edge 18 can also be continuous or, as shown in Figure 11, by means of a discontinuity.

[0050] As shown in Figure 11, the area of ​​the groove outlet 46 is at least partially covered by the end piece 30. At least one cutting element 22 of the cutting assembly 22 is arranged on the end piece 30 either without gaps or forming a gap area.

[0051] It is conceivable that at least one further cutting element 22 is arranged in series with this series of cutting elements 22. The series of cutting elements 22 is terminated in the region of the longitudinal end of the working section 11 facing away from the fastening section 14 by means of a cutting element 22 that forms a cutting end piece 21, as is clearly shown in Figure 11.

[0052] Preferably, the cutting end piece 21 terminates before the longitudinal end of the fastening groove 40, i.e., it is set back from the longitudinal end. This is also shown in Figure 11.

[0053] Figure 11 also illustrates that the cutting elements 22 are equipped with a cutting edge 22.1 facing away from the groove base 47. The cutting edge 22.1 can preferably be formed by a convex cutting surface. Preferably, the cutting edges 22.1 of at least some of the cutting elements 22 have the same cross-sectional geometry perpendicular to the longitudinal extent of the fastening groove 40. Particularly preferably, the cross-sections of at least some of the cutting elements 22 are identical.

[0054] The cutting elements 22 and also the end piece 30 are made of a hard material, in particular ceramic material or tungsten carbide.

[0055] Figure 11 also shows that, in the feed direction V or opposite to the direction of rotation D, a clearance surface 19 of the working section 11 adjoins the fastening groove 40. The groove base 47 forms a clearance angle α with the clearance surface 19, which is designed as an acute angle and is preferably selected in the range between 60° and 80°.

[0056] With reference to Figures 4-9, the design of the end piece 30 is explained in more detail below. As these illustrations show, the end piece 30 has an upper cutting edge 31 that faces away from the base 47 of the fastening groove 40. The cutting edge 31 is preferably formed by a convex cutting surface, as illustrated in Figure 7.

[0057] It is also conceivable that the cutting edge 31 is formed by a cutting edge or that the cutting edge 31 has such a cutting edge.

[0058] Opposite the cutting edge 31, the end piece 30 has a connecting section 33 on its underside. The end piece 30 can be fastened in the fastening groove 40 by means of this connecting section 33.

[0059] Preferably, the connecting piece 30 has lateral curved surfaces 33.2 on both sides in the area of ​​the connecting section 33. The lateral curved surfaces 33.2 are transitioned into one another in the area of ​​the groove base 47 of the fastening groove 40, preferably by means of a web 33.1.

[0060] As shown in Figure 7, the web 33.1 may have or form a rounding by means of which the two curved surfaces 33.2 are transitioned into one another in order to enable a stress-optimized structure.

[0061] Preferably, the end piece 30 has lateral positioning surfaces 33.3 adjacent to the lateral curved surfaces 33.2 at the connecting section 33. The lateral positioning surfaces 33.3 are preferably formed by two flat surfaces, as illustrated in Figure 7. These flat surfaces are V-shaped and angled to each other, and are transitioned into one another via a web section 33.4 of the web 33.1. Here, too, the web section 33.4 may have or form a rounded transition that transitions the positioning surfaces 33.3 into one another. The two positioning surfaces 33.3 are connected to the cutting edge 31 by means of a side section 34.3 of an edge 34 in order to avoid a sharp-edged transition in this area, as shown in Figure 7. Preferably, the two side sections 34.3 are designed as flat surface sections, at least in part.

[0062] Figure 4 shows that the edge 34 can also extend into the area of ​​the lateral curved surfaces 33.2. Preferably, the edge 34 then forms a transition between the lateral curved surface 33.2 and the cutting edge 31. Thus, the edge 34 forms a lateral edge region 34.1, as shown in Figure 4.

[0063] At its longitudinal end facing the fastening section 14, the end piece 30 has a front area 34.2, which can be formed by the edge 34. Thus, the front area 34.2 forms a blunt end, as illustrated in particular by Figure 6. Preferably, the front area 34.2 is designed in the form of a flat surface.

[0064] Preferably, the end piece 30 forms a connection surface 32 at its longitudinal end facing away from the fastening section 14. A cutting element 22 can be arranged on this connection surface 32 either without gaps or with a gap. At least partially bonded joining material, in particular solder material, can then be arranged in the gap area.

[0065] For manufacturing, the cutting elements 22, 21 are aligned in the mounting groove 40. The end piece 30 is aligned at the end facing the mounting section 14.

[0066] Figure 11 illustrates the positioning of the end piece 30 in the series. The drawing shows that preferably the groove outlet 46 is at least partially covered by the end piece 30. As Figure 11 illustrates, the end piece 30, with its front area 34.2, terminates before the transition of the groove outlet 46 into the working edge 18. This is indicated in Figure 11 by a dashed circle.

[0067] Figure 11 also illustrates that, in particular, the fastening groove 40 may form a bulge 45 in the area of ​​its groove base 47. This bulge 45 is preferably formed by a circular arc-shaped section with a radius Rg.

[0068] The end piece 30 also has an arcuate contour facing the groove base 47. This arcuate contour is preferably formed by the web 33.1 and is preferably in the form of an arcuate section with a radius Rk. Due to the different contours of the groove base 47 and the facing side of the end piece 30, a gap area with varying gap spacing results. Preferably, the radius Rk is smaller than the radius Rg in order to achieve this varying gap spacing.

[0069] In the area of ​​the gap end, the end piece 30 rests directly or indirectly on the groove base 47 with an upper support section 43 in the area of ​​the working edge 18 and with a lower support section 44 in the area facing the free end of the working section 11. The gap area is formed between the upper support section 43 and the lower support section 44. Thus, the end piece 30 is positioned with pinpoint accuracy.

[0070] Preferably, the lower support area 44 is formed by at least one of the two positioning surfaces 33.3.

[0071] In the assembled state, the cutting elements 22, 21 and the end piece 30 are preferably bonded, in particular soldered, in the mounting groove 40. Preferably, a bonding material, in particular solder, is arranged between the lateral curved surface 33.2 and the positioning surfaces 33.3 and the facing areas of the groove side walls 41, 42. Figure 15 illustrates how the mounting groove 40 can be manufactured in a simple manner according to the invention. For this purpose, a milling cutter 50 is used, which has a milling surface 52 that is contoured to match the shape of the groove side walls 41, 42 and the groove base 47. The milling cutter 50 can be rotated about its axis of rotation 51 and thereby initially creates the linear section of the mounting groove 40 from the free end of the working section 11 to the groove runout 46.To generate the groove runout 46, the milling cutter 50 is then continuously adjusted perpendicular to the axis of rotation 51 in the direction of the working edge 18 in order to generate the groove runout 46.

Claims

Claims 1. Soil cultivation tool (10) for a driven soil cultivation machine, in particular rotary harrow tines, with a tine-shaped working section (11) and a mounting section (14), wherein the working section (11) has a cutting area (12), wherein a mounting groove (40) is provided in the cutting area (12), which extends at least partially between the free end of the working section (11) and the mounting section (14) in the area of ​​a front working edge (18), wherein a cutting element (20) is mounted in the cutting area (12), wherein the cutting element (20) has an end piece (30) consisting of a hard material, in particular tungsten carbide material or ceramic material, wherein the end piece (30) is arranged at least partially in the area of ​​the end of the mounting groove (40) facing the mounting section (14) and is fastened in the mounting groove (40) with a connecting section (33).wherein the fastening groove (40) has a groove base (47) and two groove side walls (41, 42) extending laterally thereto in the longitudinal direction of the groove, characterized in that the fastening groove (40) at its end facing the fastening section (14) extends continuously into a groove run-out (46) in the direction of the working edge (18), and that the end piece (30) covers the groove run-out (46) at least partially.

2. Soil cultivation tool (10) according to claim 1, characterized in that the two groove side walls (41, 42) extend in the area of ​​the groove outlet (46) each in the form of a wall section from the groove base (47) towards the working edge (18), wherein the height of the groove side walls (41, 42) measured in the direction of the groove depth at the groove outlet (46) is reduced in the direction of the longitudinal extension of the fastening groove (40), preferably continuously reduced, and that the end piece (30) covers the groove side walls in the groove outlet (46) at least partially.

3. Soil cultivation tool (10) according to claim 1 or 2, characterized in that a gap area is formed between the connecting section (33) and the groove outlet (46) of the fastening groove (40), which is filled with a material-bonding connecting material, in particular with solder material.

4. Soil cultivation tool according to claim 3, characterized in that the gap area in the direction of the longitudinal extension of the fastening groove (40) has a varying gap height, measured in the direction of the groove depth, wherein it is preferably provided that the gap area in the longitudinal direction of the fastening groove (40) has two gap ends spaced apart from each other, and that the gap area between the gap ends has a greater gap height than the gap area at the gap ends.

5. Soil cultivation tool (10) according to one of claims 1 to 4, characterized in that the end piece (30) forms a cutting element (22) which forms a cutting edge (31) on an outer side facing away from the groove base (47), wherein it is preferably provided that the cutting edge (31) forms a convex surface, in particular a partial cylindrical surface.

6. Soil cultivation tool according to one of claims 1 to 5, characterized in that the connecting section (33) of the end piece (30) has two lateral convex curvature sections (33.2) arranged at an angle to each other, which are transitioned into one another in the area of ​​the groove base (47) of the fastening groove (40), or that the connecting section (33) forms or has a convex geometry, preferably continuously, which forms the two lateral convex curvature sections (33.2).

7. Soil cultivation tool according to one of claims 1 to 6, characterized in that the end piece (30) has a connecting surface (32) at its longitudinal end facing the free end of the working section (11), to which an adjacent cutting element (22) of the cutting attachment (20) is arranged without spacing or forming a spacing area.

8. Soil cultivation tool according to claim 7, characterized in that a gap area is formed between the arranged cutting element (22) and the connecting surface (32) of the end piece (30), and that the gap area is bridged, at least partially, by means of at least one spacer, wherein it is preferably provided that the spacer is integrally formed on the end piece (30) or the cutting element (22).

9. Soil cultivation tool according to one of claims 1 to 7, characterized in that the end piece (30) has an end section which projects towards the free end of the working section (11) over the groove outlet (46) of the fastening groove (40).

10. Soil cultivation tool according to claim 8, characterized in that the connecting section (33) of the end piece (30) extends into the area of ​​the end section, and that the end section is connected to the fastening groove (40) via the connecting section (33), preferably by a material bond.

11. Soil cultivation tool according to one of claims 1 to 10, characterized in that the connecting section (33) has two lateral positioning surfaces (33.3) extending in the direction of the longitudinal extension of the fastening groove (40), preferably flat, convex and / or concave, which each bear directly or indirectly against a groove side wall (41 , 42).

12. Soil cultivation tool according to claim 11, characterized in that the connecting section (33) of the end piece (30) has two flat positioning surfaces (33.3) which are arranged at an angle to each other, or that the connecting section (33) of the end piece (30) has two lateral convex positioning surfaces which are curved only in the direction transverse to the longitudinal extent of the fastening groove (40), in particular in the form of a partial cylindrical surface, preferably arranged on a common partial cylindrical surface.

13. Soil cultivation tool according to one of claims 1 to 12, characterized in that the end piece (30) forms a front area (34.2) at its longitudinal end facing the fastening section (14), which limits the end piece (30) and which ends in the area between the groove side walls (41 , 42) in the area of ​​the groove outlet (46).

14. Soil cultivation tool according to one of claims 1 to 13, characterized in that the cutting element (20) has a cutting end piece (21) that is arranged in the area of ​​the end of the fastening groove facing the free end of the working section, and that preferably at least one cutting element (22) is arranged between the end piece (30) and the cutting end piece (21), wherein the cutting end piece and / or the cutting element (22) are attached to the fastening groove (40).

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