Abstract
The invention relates to a cutting device for an earth working machine, having improved wear protection.
Claims
1. A cutting apparatus for an earth working machine, comprising: a carrier including: a base part; a holding extension projecting from the base part, the holding extension having a receptacle defined therein, the holding extension including a supporting segment facing away from the base part; and a mounting extension arranged on a mounting side of the base part oppositely from the holding extension; a cutting insert received at least in part in the receptacle of the holding extension, the cutting insert including a cutting tip made of a super-hard material, the cutting insert including a head at least partially covering the supporting segment; and a hard-material element formed on the holding extension in a zone of a front region relative to an advance direction of the cutting apparatus, the zone being located between the cutting tip and the base part, the zone extending so as to cover an arc-shaped area around the receptacle extending in front of the cutting insert and in a circumferential direction greater than 180 degrees and less than 360 degrees, the hard-material element extending under the head of the cutting insert throughout the zone of the front region.
2. The cutting apparatus of claim 1, wherein: the cutting tip is mounted on the head; and the head is made at least partially of a material having less wear resistance than the cutting tip but more wear resistance than a material of the holding extension.
3. The cutting apparatus of claim 2, wherein: the head is made at least partially of metal carbide.
4. The cutting apparatus of claim 1, wherein: the cutting insert includes a shank, the shank being inserted into the receptacle of the holding extension.
5. The cutting apparatus of claim 4, wherein: the cutting tip is mounted on the head; the cutting insert includes a concave transition between the head and the shank; the receptacle includes a convex transition; and a gap between the concave transition of the cutting insert and the convex transition of the receptacle is filled with joining material.
6. The cutting apparatus of claim 1, wherein: the cutting tip is mounted on the head, and the head widens proceeding from the cutting tip toward the holding extension.
7. The cutting apparatus of claim 1, wherein: the cutting tip includes a carrier body, the carrier body being joined to the head of the cutting insert, and the cutting tip further includes: at least one intermediate layer received on the carrier body; a top layer received on an outermost side of the at least one intermediate layer facing away from the carrier body; and wherein the top layer is made of a material harder than a material of the at least one intermediate layer.
8. The cutting apparatus of claim 1, wherein: the hard-material element comprises a hardfacing on the holding extension.
9. The cutting apparatus of claim 1, wherein: the hard-material element comprises at least one hard-material segment joined to the holding extension.
10. The cutting apparatus of claim 1, wherein: the cutting insert includes a deflector surface configured to guide soil removed by the cutting tip past the base part of the carrier.
11. The cutting apparatus of claim 1, wherein: the receptacle has a longitudinal center axis and has a receptacle height parallel to the longitudinal center axis; and the hard-material element extends parallel to the longitudinal center axis of the receptacle greater than or equal to the receptacle height.
12. The cutting apparatus of claim 1, wherein: the hard-material element has a thickness which decreases in a direction toward the base part.
13. The cutting apparatus of claim 12, wherein: the thickness of the hard-material element decreases from adjacent the supporting segment to an end of the hard-material element nearest the base part.
Description
(1) The invention will be explained in further detail below with reference to exemplifying embodiments illustrated by the drawings, in which:
(2) FIG. 1 is a partly sectioned perspective side view of a carrier having a cutting insert;
(3) FIG. 2 schematically depicts, in a side view and in section, a detail taken from FIG. 1;
(4) FIG. 3 shows what is depicted in FIG. 2, in plan view and as a first variant of the invention;
(5) FIG. 4 shows what is depicted in FIG. 2, in plan view and as a second variant of the invention;
(6) FIG. 5 is a partly sectioned side view of a carrier having a cutting insert, as a further embodiment of the invention;
(7) FIG. 6 shows a sectioned detail, taken from FIG. 5, along section line VI;
(8) FIG. 7 is a schematic depiction, in vertical section, of a cutting tip of a cutting insert in accordance with the variants of the invention shown in FIG. 1 and FIGS. 6 to 8;
(9) FIG. 8 is a perspective side view of a further variant embodiment of a carrier having a cutting element.
(10) FIG. 1 shows a carrier 10 that is made of a steel material. Carrier 10 possesses a base part 11 having a mounting side and a working side. Four supporting surfaces 12 are arranged in the region of the mounting side. These supporting surfaces 12 are angled with respect to one another. Front and rear supporting surfaces 12 are provided. Front supporting surfaces 12 extend in the region of the underside of a skirt 13 of base part 11. Skirt 13 is arranged at the front in the advance direction. A mounting extension 14 is furthermore arranged in the region of the mounting side of carrier 10. In the context of the invention, mounting extension 14 can also be embodied as an insertion extension, as shown by way of example in FIG. 1. Mounting extension 14 can comprise a mounting receptacle 15 on the rear side oppositely to the advance direction. On the front side, mounting extension 14 possesses two supporting surfaces 16 arranged spaced apart from one another by way of a recess 17. Mounting receptacle 15 is embodied to receive the end of a compression screw. The compression screw introduces into mounting extension 14, via the mounting receptacle, a pulling-in force proceeding along the longitudinal extent of mounting extension 14. This force not only acts along the longitudinal axis of mounting extension 14, but also presses the two front supporting surfaces 16 onto corresponding counter-surfaces of a lower part of a quick-change bit holder.
(11) Base part 11 carries a holding extension 20 in the region of the working side. As FIG. 1 shows, holding extension 20 projects beyond base part 11 with a preferably cylindrical extension. Holding extension 20 possesses a conical taper at the end. The free end of the conical taper is constituted by a supporting segment 24. Recessed into supporting segment 24 is a bore that constitutes a receptacle 21. As FIG. 1 shows, holding extension 20 is covered surroundingly, in the region of taper surface 23, by a hard-material element 22. This hard-material element 22 is embodied as a hardface weld. A cutting insert 30 is introduced into receptacle 21. Cutting insert 30 possesses a cutting tip 31 whose configuration will be explained in further detail later. Cutting tip 31 is joined via a joining piece 32, for example made of metal carbide, to a head 33 of cutting insert 30. A shank 34 is shaped onto head 33. Shank 34 is inserted into receptacle 21. The component comprising head 33 and shank 34 can be made, for example, of metal carbide. In particular, the hardness of this component is selected to be greater than the hardness of support 10 but less than the hardness of cutting tip 31.
(12) As is apparent from FIG. 2, shank 34 transitions via a concave transition into head 33. The oppositely located receiving region of receptacle 21 is correspondingly embodied concavely. As FIG. 2 shows, a gap region that is filled with solder material 35 is constituted between shank 34 and receptacle 21. Head 33 is thus in particular also supported on supporting segment 24 with interposition of solder material. This is advantageous because a risk of breakage is avoided thanks to this gap-free attachment. Stress peaks in the transition region between shank 34 and head 33 are reduced by way of the concave/convex surface pairing. Any other inter-materially bonded join can also be provided instead of solder material 35. It is furthermore conceivable for shank 34 to be shrink-fitted into receptacle 21. Also evident from FIG. 2 is hard-material element 22 that surrounds holding extension 20 in the region of taper surface 23. Hard-material element 22 is embodied and arranged in such a way that, with its height h, it completely covers the height of receptacle 21 in order to afford suitable protection from erosion. As FIG. 2 shows, it is also conceivable in the context of the invention for the hardface weld not to consistently have the same thickness. A varying thickness is instead conceivable in order to achieve appropriate wear behavior. For example, provision can be made that the thickness of hard-material element 22 decreases along the longitudinal center axis of the cutting insert.
(13) Hard-material element 22 can be applied surroundingly. It is also conceivable, however, for hard-material element 22 to be arranged on holding extension 20 over an arc sector, as is evident from FIGS. 3 and 4. As FIG. 3 shows, the arc length I in a circumferential direction of holding extension 20 should preferably be selected to be greater than the diameter of receptacle 21, or greater than the diameter of head 33. Hard-material element 22 also need not have a uniform thickness in a circumferential direction. Provision can instead also be made that the thickness varies in a circumferential direction, preferably decreases oppositely to the advance direction.
(14) FIGS. 5 and 6 show a further exemplifying embodiment of the invention. As FIG. 5 shows, hard-material element 22 is constituted by hard-material segments that are mounted on holding extension 20. Hard-material elements 22 can be constituted, for example, by metal carbide elements that are applied by inter-material bonding onto holding extension 22. As FIG. 6 shows, hard-material elements 22 can be constituted by hard-material segments 22.1. For example, hard-material segments 22.1 can be plate-shaped. It is also conceivable, as shown in FIG. 6, for hard-material segments 22.1 to comprise a covering portion 22.2 onto which a mounting extension 22.3 is shaped. Hard-material segments 22.1 are introduced with mounting extension 22.3 into mounting receptacles 22.4 of holding extension 22. Hard-material segments 22.2 are joined by inter-material bonding, in particular soldered, to holding extension 20 in the region of mounting extension 22.3 and of the underside of covering portion 22.2. An example of the configuration of cutting tip 31 is evident from FIG. 7. A carrier body 31.1, for example made of metal carbide, is used, and an intermediate layer 31.2 is layered onto this. It is also conceivable for two or several intermediate layers 31.2 to be used. A top layer 31.3 is layered onto intermediate layer 31.2. Top layer 31.3 preferably possesses a concentration of polycrystalline diamond. Intermediate layer 31.2 likewise possesses a concentration of polycrystalline diamond. The concentration of polycrystalline diamond is higher in top layer 31.3 than in intermediate layer 31.2.
(15) FIG. 8 shows a further variant embodiment of the invention. As is evident from this illustration, carrier 10 corresponds substantially to the configuration of carrier 10 according to FIG. 1, and therefore only the differences will be discussed hereinafter. In contrast to carrier 10 according to FIG. 1, carrier 10 according to FIG. 8 possesses a holding extension 25 that is shaped onto base part 11 facing away from mounting extension 14. Holding extension 25 comprises two abutment surfaces 26 and 27 angled with respect to one another. Abutment surface 27 is directed in advance direction V, and abutment surface 26 is directed oppositely to the advance direction. Cutting element 40 is placed onto the two abutment surfaces 26, 27 with interposition of an inter-materially bonded join, for example a solder join. Cutting element 40 possesses a head 43 that forms a mounting piece 45. Mounting piece 45 comprises two deflector surfaces 46 inclined in the advance direction. An extension 44 is shaped onto the rear side of mounting piece 43. Cutting element 40 abuts, with mounting piece 43 and extension 44, against abutment surfaces 26 and 27, as has been described above. Head 43 again carries a cutting tip 31 that is constructed in principle similarly to cutting tip 31 in accordance with the variant embodiments of FIGS. 1 to 7. Cutting tip 31 is, however, configured asymmetrically with respect to its longitudinal center axis and has a greater volume in its radially external region than in its radially internal region. This affords an increased wear volume in the region of the outer cutting edge of cutting tip 31. Cutting tip 31 is supported via joining piece 32, oppositely to the advance direction, on head 33 and is mounted there, preferably attached via an inter-materially bonded join, in particular a solder join.
