CUTTING ELEMENT

Abstract

A cutting element, in particular for abrasive cut material, is provided that includes a substrate that defines at least one cutting wedge which is formed by first and second wedge surfaces that intersect along a wedge edge. A cutting layer that extends over the first wedge surface and defines a cutting edge which lies on the wedge edge when new. The wear resistance of the cutting layer is greater than wear resistance of the substrate. The cutting layer is configured to define a blade-shaped protrusion that projects beyond the wedge edge due to wear of the substrate in the area of the second wedge surface to provide a self-resharpening cutting edge. The cutting layer or part thereof is formed by means of melt-metallurgical modification of an edge zone of the substrate by in-situ precipitation of finely dispersed inherent hard phases from partial melting of the edge zone of the substrate.

Claims

1. A cutting element, comprising: a substrate that defines at least one cutting wedge which is formed by first and second wedge surfaces that intersect along a wedge edge; and a cutting layer that extends over the first wedge surface and defines a cutting edge which lies on the wedge edge when new; wherein wear resistance of the cutting layer is greater than wear resistance of the substrate; wherein the cutting layer is configured to define a blade-shaped protrusion that projects beyond the wedge edge due to wear of the substrate in the area of the second wedge surface to provide a self-resharpening cutting edge; and wherein the cutting layer or part thereof is formed by means of melt-metallurgical modification of an edge zone of the substrate by in-situ precipitation of finely dispersed inherent hard phases from partial melting of the edge zone of the substrate.

2. A cutting element according to claim 1, wherein: the cutting layer extends below the first wedge surface.

3. A cutting element according to claim 1, wherein: the cutting element is configured to cut abrasive cut material.

4. A cutting element according to claim 1, wherein: the wear resistance of the cutting layer is greater than the wear resistance of the substrate by at least 10%; or the wear resistance of the cutting layer is greater than the wear resistance of the substrate by at least 25%.

5. A cutting element according to claim 1, wherein: the thickness of the cutting layer is 0.1 to 1.0 mm; or the thickness of the cutting layer is 0.2 to 0.6 mm.

6. A cutting element according to claim 1, wherein: thickness of the cutting layer varies across the surface of the cutting layer.

7. A cutting element according to claim 1, wherein: the cutting layer comprises only one or multiple partial surfaces of the first wedge surface.

8. A cutting element according to claim 1, wherein: the edge zone of the substrate is subjected to a beam-assisted melt-metallurgical modification.

9. A cutting element according to claim 1, wherein: the edge zone of the substrate is melt-metallurgically modified by partial melting of the edge zone of the substrate while substantially retaining the geometry of the cutting wedge.

10. A cutting element according to claim 1, wherein: the edge zone of the substrate is melt-metallurgically modified by precipitating the finely dispersed inherent hard phases directly from the partially melted edge zone of the substrate and rapid solidification as a result of self-quenching via rapid heat dissipation into the interior of the substrate.

11. A cutting element according to claim 1, wherein: the finely dispersed inherent hard phases have a micro-hardness of at least 2100 HV; or the finely dispersed inherent hard phases have a micro-hardness of at least 2800 HV.

12. A cutting element according to claim 1, wherein: the finely dispersed inherent hard phases have a volume fraction of at least 5% in the cutting layer; or the finely dispersed inherent hard phases have a volume fraction of at least 10% in the cutting layer.

13. A cutting element according to claim 1, wherein: the finely dispersed inherent hard phases have a volume fraction that varies in the cutting layer.

14. A cutting element according to claim 1, wherein: the finely dispersed inherent hard phases have a mean free distance of less than 20 μm; or the finely dispersed inherent hard phases have a mean free distance of less than 10 μm.

15. A cutting element according to claim 1, wherein: the finely dispersed inherent hard phases comprise carbides, borides, nitrides or oxides.

16. A cutting element according to claim 1, wherein: the finely dispersed inherent hard phases comprise monocarbides of a refractory alloying element.

17. A cutting element according to claim 16, wherein: the refractory alloy element comprises vanadium, titanium or niobium carbides.

18. A cutting element according to claim 1, wherein: the melt-metallurgical modification of the edge zone of the substrate involves introducing a powdery filler material.

19. A cutting element according to claim 18, wherein: the powdery filler material comprises a monocarbide-forming refractory alloying element.

20. A cutting element according to claim 1, wherein: the substrate comprises a steel alloy containing at least one carbide-forming alloy element.

21. A cutting element according to claim 20, wherein: the at least one carbide-forming alloy element comprises vanadium, titanium, niobium or chromium.

22. A method for manufacturing a cutting element, comprising: i) providing a substrate; ii) mechanically processing the substrate with near-net-shape preforming of at least one cutting wedge defined by first and second wedge surfaces which intersect along a wedge edge; and iii) forming a wear-resistant cutting layer that starts at the wedge edge by means of melt-metallurgical modification of an edge zone of the substrate by in-situ precipitation of finely dispersed inherent hard phases of the substrate.

23. A method according to claim 22, wherein: the cutting layer extends below the first wedge surface.

24. A method according to claim 22, wherein: the melt-metallurgical modification of the edge zone of the substrate involves introducing a powdery filler material.

25. A method according to claim 24, wherein: the powdery filler material comprises a carbide-forming refractory alloying element.

26. A method according to claim 25, wherein: the carbide-forming refractory alloying comprises vanadium, titanium or niobium.

27. A method according to claim 22, wherein: the melt-metallurgical modification of the edge zone of the substrate is carried out continuously along the wedge edge by means of a high-energy beam.

28. A method according to claim 22, wherein: the melt-metallurgical modification of the edge zone of the substrate is performed in areas close to the surface to a depth of about 1 mm while substantially retaining the geometry of the cutting wedge.

29. A cutting device, comprising: a chopping drum with at least one cutting element according to claim 1; and fixed counter-blade that cooperates with the at least one cutting element.

30. A forage harvester, comprising: a rotating chopping drum with at least one cutting element according to claim 1; and fixed counter-blade that cooperates with the at least one cutting element.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0040] In the following, the present disclosure describes embodiments of a cutting element by way of example with reference to schematic drawings of a blade for the chopping drum of a forage harvester.

[0041] FIG. 1 shows a side view of a prior art blade.

[0042] FIG. 2 shows the wear of a prior art blade during use in a side view.

[0043] FIG. 3 shows a side view of a blade according to the present disclosure.

[0044] FIG. 4 shows the wear of a blade according to the present disclosure during use in a side view.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0045] In FIG. 1, a new prior art flat blade for the chopping drum of a forage harvester is schematically shown in a side view. The blade made of a substrate 1 of martensitic or bainitic steel usually has a thickness of 5 to 15 mm, a width of 50 to 150 mm, a length of 150 to 450 mm and, in addition to the flat shape shown, can also be designed in a spatially curved shape. Furthermore, the blade has recesses in the substrate area outside the cutting wedge 2 for being fastened to the blade carriers of the chopping drum by means of fastening elements, which are omitted for the sake of a clearer representation. The cutting function of the blade is performed by an acute-angled cutting wedge 2, which has a wedge edge 3 and is enclosed by a first wedge surface 4 and a second wedge surface 5. When new, the cutting edge 6 extends along the wedge edge 3 and is part of the cutting layer 7, which is applied to the first wedge surface 4 in the form of a hard material coating by a thermal spraying process and is subsequently sintered by means of a flame, inductively or in a furnace. In prior art blades, the hard material coating has a thickness of 0.2 to 0.6 mm and a width of 10 to 30 mm.

[0046] As can be seen in the schematic side view of a prior art blade for the chopping drum of a forage harvester during use in FIG. 2, the impact stress caused by coarse foreign bodies in the cut material leads, as a result of the disadvantages of the prior art design of the cutting layer 7 already described, to failure of the cutting layer 7 by breaking away of the cutting layer 7, detachment of the cutting layer 7 from the wedge surface 4 of the substrate 1 and breaking off of the protrusion 9 of the cutting layer 7, which temporarily projects beyond the substrate 1 in the area of the second wedge surface 5 due to leading wear 8 of the substrate 1, and thus to rounding 10 of the cutting wedge 2. This rounding 10 of the cutting wedge 2 results in a significant deterioration of the cutting quality and a massive increase in fuel consumption. In order to remove the rounding 10 of the cutting wedge 2, frequent regrinding of the second wedge surface 5 is necessary and with the associated material removal on the cutting wedge 2, the service life of the blade is significantly shortened.

[0047] FIG. 3 shows a schematic representation of an exemplary embodiment of the present disclosure in the form of a new blade for the chopping drum of a forage harvester in a side view. As in the prior art blade, the steel substrate 1 has a cutting wedge 2, whose wedge surfaces 4 and 5 form the wedge edge 3, which in turn supports the cutting edge 6. In contrast to the prior art blade, however, the cutting layer 7 extending from the cutting edge 6 lies predominantly below the first wedge surface 4 and the cutting layer 7 embedded in the substrate 1 is formed by means of melt-metallurgical modification of the edge zone of the substrate 1 by in-situ precipitation of finely dispersed inherent hard phases from partial melting of the edge zone of the substrate 1. The partial melting of the edge zone of the substrate 1 is carried out while essentially retaining the geometry of the preformed cutting wedge 2. This near-net-shape modification of the edge zone of the substrate is made possible in particular by supplying energy via a high-energy beam, which only takes place in areas very close to the surface up to about 1 mm, and offers the advantage that no or only very little mechanical reworking of the cutting wedge is required.

[0048] FIG. 4 shows a side view of the advantageous wear pattern of a blade according to the present disclosure during use. As a result of the advantages of the design of the cutting layer 7 as described herein, the cutting layer 7, which starts at the cutting edge 6, is embedded in the substrate 1 and lies predominantly below the first wedge surface 4, does not break out or detach from the wedge surface 4 of the substrate 1 when subjected to impact stress by coarse foreign bodies in the cut material. Instead, due to leading wear 8 of the substrate 1, in the area of the second wedge surface 5, a blade-shaped protrusion 9 forms, which projects beyond the wedge edge 3 of the cutting wedge 2 and has a self-resharpening cutting edge 6. Due to the advantageous material properties of the design according to the present disclosure, the blade-shaped protrusion 9 of the cutting layer 7 does not break off even when subjected to impact stress by coarse foreign bodies in the cut material. Due to the lasting self-sharpening effect made possible by this, the frequency of regrinding on the second wedge surface 5 can be significantly reduced and the service life of the blade extended accordingly.

[0049] There have been described and illustrated herein several embodiments of a cutting element and a method of forming same. While particular configurations have been disclosed in reference to the cutting element, it will be appreciated that other configurations could be used as well. It will therefore be appreciated by those skilled in the art that yet other modifications could be made to the provided invention without deviating from its spirit and scope as claimed. Thus, the invention is not limited to the exemplary embodiment shown, but can be applied generally to cutting elements for cutting abrasive cut material that is subjected to impact stress.

LIST OF REFERENCE SIGNS

[0050] 1 Substrate [0051] 2 Cutting wedge [0052] 3 Wedge edge [0053] 4 First wedge surface [0054] 5 Second wedge surface [0055] 6 Cutting edge [0056] 7 Cutting layer [0057] 8 Wear of the substrate [0058] 9 Protrusion of the cutting layer [0059] 10 Rounding of the cutting wedge