EP4072804A1

EP4072804A1 - Cutting element and the use thereof

Info

Publication number: EP4072804A1
Application number: EP20812090.7A
Authority: EP
Inventors: Michael Magin; Louis Patrick Fetcheping KEMDEM
Original assignee: Ceratizit Luxembourg SARL
Current assignee: Ceratizit Luxembourg SARL
Priority date: 2019-12-12
Filing date: 2020-12-01
Publication date: 2022-10-19
Also published as: US20230001487A1; JP2023505342A; EP3835018A1; CN114786896B; WO2021115836A1; CN114786896A

Abstract

The invention relates to a cutting element (1) which is designed for cutting a non-metallic composite material of a matrix and particles held together by the matrix, comprising a flank (4), a face (5) and a cutting edge (6) coated with an edge coating (2) by which edge the flank (4) and the face (5) are connected to one another, with which the non-metallic composite material can be machined in an improved manner, such that the cutting edge (6) is curved within a cutting edge portion (8), and away therefrom, such that the cutting edge (2) has, at any point in the cutting edge portion (8) immediately below the edge coating (2) in a section in a section plane that is perpendicular to the cutting edge (6), a local curvature radius (9) which is greater than or equal to 10 μm and smaller than or equal to 80 μm, preferably greater than or equal to 15 μm and smaller than or equal to 60 μm, even more preferably greater than or equal to 20 μm and smaller than or equal to 40 μm.

Description

CUTTING ELEMENT AND USE OF IT

The present invention relates to a cutting element which is designed for machining a non-metallic composite material from a matrix and particles held together by the matrix, having a free face, a rake face and a cutting edge coated by an edge coating, by means of which the free face and the rake face are connected to one another.

The present invention also relates to a use of the cutting element.

In the case of the non-metallic composite material, the particles are formed, for example, by wood, for example in the form of wood chips or wood fibers, or by carbon, for example in the form of carbon fibers, or glass, for example in the form of glass fibers, or a natural or synthetic mineral Origin, for example in the form of mineral fibers. The matrix is based, for example, on one or more organic compounds, in particular in the form of a plastic.

In the case of wood chips and wood fibers, the matrix is formed by a certain plastic, namely an adhesive, for example a glue, the wood chips or wood fibers are soaked in it and then pressed. If the wood chips are used, for example, chipboard is produced in this way, whereas the wood fibers are used, for example so-called medium-density fiberboard (MDF) or high-density fiberboard (HDF). MDF boards and HDF boards are also usually provided with a plastic coating, varnish or veneer, because this can be visually appealing, which makes machining even more demanding.

In the case of carbon fibers and glass fibers, which can be divided into short or long fibers depending on their length (the same can also be applied to wood fibers), the matrix is formed by a plastic. Corresponding to these particles, the non-metallic composite material formed in this way is referred to as carbon fiber reinforced plastic (CFRP) or glass fiber reinforced plastic (GFRP).

When machining the non-metallic composite material, which is fundamentally different from the machining of metals and alloys, abrasive wear usually occurs primarily on a cutting edge, but also on the adjacent areas of the flank and the rake face. If the closure has progressed too far, the quality of the machined non-metallic composite material is no longer acceptable. The generic cutting element previously known from WO 2012/162849 A1 is therefore coated. The service life is accordingly increased compared to an uncoated cutting element.

However, in the case of the previously known cutting element, the coating tends to flake off when the cutting edge is heavily loaded. This reduces the service life actually achievable through the edge coating.

The object of the present invention is therefore to provide a cutting element and a use with a longer service life, according to which the non-metallic composite material can be machined in an improved manner, in particular in the form of a chipboard, MDF, H DF, GRP or CFRP.

This object is achieved by a cutting element according to claim 1. Advantageous further developments are given in the dependent claims.

The cutting element, which is designed for machining a non-metallic composite material from a matrix and particles held together by the matrix, has a flank, a rake face and a cutting edge coated by an edge coating, through which the flank and the rake face are connected to one another, the Cutting edge within a cutting edge portion thereof is curved in such a way that the cutting edge immediately below the edge coating in a section in a cutting plane which is perpendicular to the cutting edge, at each point of the cutting edge portion has a local radius of curvature which is greater than or equal to 10 μm and less than or equal to 80 pm, preferably greater than or equal to 15 pm and less than or equal to 60 pm, even more preferably greater than or equal to 20 pm and less than or equal to 40 pm. This provides a rounded cutting edge which makes the cutting element sufficiently sharp (the edge coating that engages the non-metallic composite material during machining can follow the edge coating, for example because it was deposited on it), and at the same time is sufficiently curved, this is due to the radius of curvature at each point of the cutting edge section in the section in the cutting plane, in order to ensure the adhesion of the edge coating in an improved manner. The cutting edge can then be circular or elliptical or otherwise rounded within the cutting edge section in the section in the cutting plane. The cutting edge section can be symmetrical or asymmetrical in the section in the cutting plane.

The flank face and / or the rake face can each have one or more chamfers before they are connected to one another by the cutting edge. The flank face and / or the rake face can be flat, faceted or curved, or be formed by a combination thereof.

The cutting edge can be straight or curved between two outer corners of the cutting element, or a combination thereof; a normal vector of the vertical cutting plane is parallel to a tangent placed on the cutting edge at a point.

According to a further development of the cutting element, the cutting edge section extends over at least 50%, preferably at least 70%, even more preferably at least 90% of the cutting edge in the cut in the cutting plane. This improves the adhesion of the edge coating within this section because it is slightly curved in accordance with the radius of curvature. In the case of a radius of curvature that is constant in all points, it is particularly advantageous if the cutting edge section extends over 100%, that is to say the entire cutting edge in the section in the cutting plane.

The edge coating is preferably designed following the shape of the cutting edge, i.e. curved in such a way that in the section in the cutting plane that is perpendicular to the cutting edge it has a different local radius of curvature at each point, which is greater than the radius of curvature at the opposite one Point of the cutting edge immediately below the edge coating.

The composition of the edge coating, which can comprise a plurality of individual layers or just one layer, is different from the composition of the cutting edge, that is to say the corresponding composition of a substrate body which forms the cutting edge, the rake face and the rake face. As a result, the edge coating forms an outer cutting edge of the cutting element opposite the cutting edge section, which is sufficiently sharp and at the same time adheres sufficiently to the substrate body due to the curved cutting edge. According to a further development of the cutting element, the radius of curvature is the same in at least two different, preferably in all, of the points of the cutting edge section in the section in the cutting plane. If it is the same in all points, the cutting edge in the section in the cutting plane is circular, which is particularly good for the adhesion of the edge coating in view of the fact that it is.

According to a development of the cutting element, a wedge angle in the section in the cutting plane is defined by the flank and the rake face, the position and the radius of a circle in the section in the cutting plane is defined by a smallest radius of curvature of the radii of curvature and is a point on a through the bisector defined by the center of this circle. As a result, the cutting edge achieves its maximum cutting sharpness at an outer point thereof, with sufficient adhesion of the edge coating being provided there at the same time. This is a shape which is particularly well suited for machining the non-metallic composite material if this is followed by the edge coating. The vertex of the wedge angle lies outside of the cutting edge section (it can, if necessary, lie within the edge coating), one of its angled legs touches the rake face and its other angled leg touches the flank. The vertex is a point on the bisector through which the inner wedge angle, i.e. the wedge angle facing the cutting edge, is halved. This is because this makes the cutting edge particularly sharp while maintaining sufficient adhesion of the edge coating.

According to a development of the cutting element, the cutting edge is formed at least in the area of the cutting edge section by a flart metal or cermet. Since the cutting edge and thus a corresponding substrate body of the cutting element, which also forms the cutting edge, are formed in the area of the cutting edge by one of these materials, the service life of the cutting element is increased even further because they are particularly hard and wear-resistant.

For the purposes of the present disclosure, cemented carbide and cermet are each composite materials in which hard material particles, which make up the predominant component of the composite material, form a skeletal or framework structure, the interstices of which are filled by a more ductile metallic binder. The FH a rtstoffparti ke I can in particular at least predominantly by tungsten carbide, titanium carbide and / or titanium carbonitride be formed, with additional z. B. other hard material particles, in particular carbides of the elements of groups IV to VI of the periodic table, may be present. The ductile metallic binder usually consists at least predominantly of cobalt, nickel, iron or a base alloy of at least one of these elements. However, other elements can also be dissolved in the metallic binder in smaller quantities. A base alloy is understood to mean that this element forms the predominant component of the alloy. Most frequently, hard metal is used in which the hard material particles are at least predominantly formed by tungsten carbide and the metallic binder is a cobalt or cobalt-nickel-based alloy; the proportion by weight of the corresponding tungsten carbide particles is in particular at least 70 percent by weight, preferably more than 80 percent by weight, even more preferably more than 90 percent by weight, this proportion by weight preferably in the range from 70 percent by weight to 99 percent by weight, even more preferably from 80 percent by weight to inclusive 99 percent by weight inclusive, most preferably from 90 percent by weight to 99 percent by weight inclusive, or from 94 percent by weight to 99 percent by weight inclusive.

In the context of the present disclosure, skeletal structure means that the hard material particles, for example hard material particles essentially formed by tungsten carbide, form a coherent particle network where any hard material particle touches at least one other hard material particle.

According to a development of the cutting element, the cutting edge is formed at least in the area of the cutting edge section by a hard metal, the hard metal having hard material particles, the hard material particles forming a skeletal structure of the hard metal and the hard material particles having a grain size in the range from 0.1 μm to 1.5 μm , preferably from 0.15 pm to 0.8 pm, even more preferably from 0.2 pm to 0.5 pm. The grain size in one of these ranges (from 0.1 .mu.m to 1.5 .mu.m, preferably from 0.15 .mu.m to 0.8 .mu.m, even more preferably from 0.2 .mu.m to 0.5 .mu.m) gives the cutting edge a particularly stable one Adhesion from the edge coating, so that the life of the edge coating is extended. The hard material particles in one of these areas (from 0.1 μm to 1.5 μm, preferably from 0.15 μm to 0.8 μm, even more preferably from 0.2 μm to 0.5 μm) are preferably essentially made up of tungsten carbide educated. In the context of the present disclosure, formed essentially by tungsten carbide means that at least 90% of the hard material particles are formed by tungsten carbide, preferably 95%, most preferably 99%. The same applies to cases in which the hard material particles are essentially formed by a different hard material phase.

In the present disclosure, the grain size is measured as "linear intercept length" in accordance with the international standard ISO 4499-2: 2008 (E). EBSD recordings (EBSD, electron back-scatter diffraction) served as the basis is described for example in: KP Mingard et al., Comparison of EBSD and conventional methods of grain size measurement of hard metals ", Int. Journal of Refractory Metals & Hard Materials 27 (2009) 213-223.

The weight fraction of the hard material particles with a grain size in the range from 0.1 μm to 1.5 μm, preferably from 0.15 μm to 0.8 μm, even more preferably from 0.2 μm to 0.5 μm, can in particular be in the range from 70 percent by weight to 99 percent by weight inclusive, more preferably from 80 percent by weight to 99 percent by weight inclusive, most preferably from 90 percent by weight to 99 percent by weight inclusive, or from 94 percent by weight to 99 percent by weight inclusive.

According to a development of the cutting element, the edge coating is formed at least in the region of the cutting edge by at least one deposited hard material layer, where the edge coating is formed on the cutting edge section. As a result, the service life of the cutting element is increased even further, because such a hard material layer is particularly wear-resistant and it is designed to follow the cutting edge, that is to say is correspondingly curved.

This development is further improved if the hard material layer is formed by diamond, amorphous carbon, cubic boron nitride or T1B2. This further improves the service life. A plurality of polycrystalline hard material layers formed by diamond are particularly preferably deposited on the cutting edge section and thus the corresponding substrate body, in particular if this is formed by the hard metal or cermet. One or more hard material layers formed by the amorphous carbon are preferably on the cutting edge section and thus the corresponding substrate body, in particular if this is formed by the hard metal or cermet, deposited. Amorphous carbon is also known under the names DLC (diamond-like carbon) or diamond-like carbon. The layer or layers formed by amorphous carbon are preferably those that contain hydrogen, the hydrogen content being at least 35 atomic percent (remainder carbon), so-called a: C, aC: H amorphous carbon, or those in which the carbon is tetrahedral, the hydrogen content being at least 25 atomic percent (remainder carbon) and the carbon sp ^{3 being} hybridized, so-called ta: C, taC: H amorphous carbon.

According to a further development of the cutting element, the edge coating is designed to extend onto the flank face and / or onto the rake face. This increases the service life of the cutting element on one or both of these surfaces. The microhardness of the edge coating, where it is formed on the flank face and / or on the rake face, preferably corresponds to the microhardness of the edge coating, where the edge coating is formed on the cutting edge section.

According to a further development of the cutting element, a layer thickness of the edge coating, at least in the area of the cutting edge, is greater than or equal to 0.5 μm and less than or equal to 20 μm, preferably greater than or equal to 5 μm and less than or 20 μm, where the edge coating is formed on the cutting edge section. These are layer thicknesses which, in particular, but not only in the case of the deposited diamond fluff layer or several layers thereof and the deposited fl argent layer made of amorphous carbon or several layers thereof, further increase the service life. In the context of the present disclosure, the layer thickness is defined as the smallest distance from the outer surface of the edge coating to the cutting edge section and thus the corresponding substrate body in the area thereof, that is, perpendicular to a tangential plane applied to the edge coating.

According to a development of the cutting element, the edge coating is formed at least on the cutting edge section by a PVD or a CVD deposition process. The edge coating is accordingly deposited in the manner known to the person skilled in the art by means of PVD (physical vapor deposition) or CVD (chemical vapor deposition); However, other methods for this are also conceivable and also possible. The at least one flare material layer thus deposited is preferably on its outer surface after the deposition of a Surface treatment by, for example, wet blasting or the like, in order to smooth them and, if necessary, to reduce internal stresses in them.

According to a development of the cutting element, it is designed as a cutting knife. A knife edge is then formed by the cutting edge, which is particularly useful for the machining of the composite material, especially if the particles are formed by wood chips or wood fibers, the cutting element is flat, in particular for the mostly flat removal of thin layers from the composite material. This is in contrast to a cutting element, which is designed for the machining of metals and alloys from them.

According to a further development of the cutting element, it is formed on a drilling tool, milling tool or planing tool. The service life thereof, which is increased by the curved cutting edge of the cutting element, is advantageously reflected on these tools.

In particular, the cutting element has these tools, so that a drilling tool, a milling tool or a planing tool with the cutting element or several thereof is provided in the sense of the present disclosure.

According to a further development, the particles are formed by wood chips or wood fibers and the matrix is formed by an adhesive. The increased service life of the cutting element is particularly beneficial because the composite material formed afterwards is particularly abrasive. Alternatively, the particles can be formed by carbon fibers or glass fibers and the matrix

According to a further development of the cutting element, it is designed for machining the non-metallic composite material if it is a chipboard, MDF, HDF, CFRP or GFRP.

The object is also achieved by the use according to claim 13, that is to say by using a cutting element according to claim 1 or a claim dependent thereon or the disclosed developments or embodiments of the cutting element for machining for machining the non-metallic composite material. The cutting element is then used in particular to separate the non-metallic composite material in a predetermined manner, for example by milling or planing, the curved cutting edge for a particularly clean cut even at high cutting speeds and longer cutting time. The non-metallic composite material can be formed in some areas from a chipboard, MDF or HDF and in the remaining area from GRP or CFRP (this can be referred to as a hybrid non-metallic composite material), the cutting element being used to run both areas one after the other or together, for example along a common interface, to be machined.

The use of the cutting element is further improved if the particles are formed by wood chips or wood fibers and the matrix is formed by an adhesive. The advantage of the cutting element comes into play particularly well, because in the chipboard formed in this way in the case of the wood chips and the MDF and FH DF formed in this way in the case of the wood fibers, particularly clean cuts can be produced thereby, while at the same time the service life through better adhesion of the Cutting edge coating is increased.

The use of the cutting element is also improved if the particles are formed by carbon fibers or glass fibers and the matrix is formed by a plastic.

A CFRP or a GFRP is therefore provided. The advantage of the cutting element comes into its own here, because particularly clean cuts can be produced in the CFRP and GFRP, while at the same time the service life is increased due to better adhesion of the cutting edge coating.

The use of the cutting element is further improved if a veneer, a plastic layer or a coating is formed on a surface of the composite material, in particular if the particles are formed by wood fibers or wood chips. Then the improved service life with sufficient cutting sharpness comes into play even better, because these surface materials tear particularly easily.

Further advantages and expediencies of the invention emerge from the following description of an exemplary embodiment with reference to the accompanying figures.

From the figures show:

1: a perspective, schematic and partial cross-sectional illustration of a coated cutting element in the area of its cutting edge, free surface and rake face;

FIG. 2: a detailed representation of the cutting element from FIG. 1 in section in a sectional plane perpendicular to the cutting edge; FIG. Fig. 3: Detailed representation of the cutting element according to FIG. 2 with additionally shown

Wedge angle.

1 shows a perspective, schematic and sectional cross-sectional illustration of a cutting element 1 for cutting a non-metallic composite material within the meaning of the present disclosure; a sectional view was therefore rotated in perspective so that the cross section and the rest of the structure of the cutting element 1 can be seen therefrom.

The cutting element 1 is coated with a fluff layer 2 made of precipitated polycrystalline diamond. The flare material layer 2 was deposited on a wedge-shaped substrate body 3, which is formed by a tungsten carbide-containing flart metal, of the cutting element 1, namely on a flat free surface 4, a flat rake surface 5 and a curved cutting edge 6 through which the free surface 4 and the rake face 5 are connected; However, several flare layers 2 made of the deposited diamond or another flare such as amorphous carbon are also conceivable and also possible.

The flank face 4, the rake face 5 and the cutting edge 6 are therefore coated with the flare material layer 2; it thus protects the substrate body 3, which is softer by comparison, from wear during machining. The actual engagement in the non-metallic composite material during machining is thus formed by the flare material layer 2, which follows the shape of the substrate body 3, i.e. is curved where the cutting edge 6 is formed and is flat where the flank 4 and rake face 5 are formed are. Although the substrate body 3 is basically suitable for machining the non-metallic composite material, it is usually not sufficiently wear-resistant. 2, accordingly, the Flartstoffschicht outwardly, ie facing the non-metallic composite material one of the cutting edge 6 of the following and, accordingly, curved cutting edge 6 ^', one of the free surface 4 of the following planar clearance surface ^4' and the rake face 5, the following planar clamping surface 5 ^'; the longitudinal extension of the cutting edge 6 ^' is covered by the longitudinal extension of the cutting edge 6 ^' . In other words, by means of linear scaling, the contour of the substrate body 3 can be converted into the outer contour of the fluff layer 2 and vice versa. The layer thickness of the hard material layer 3 is shown as constant by way of example, this being determined by the smallest distance between its surfaces (free surface 4 ^' , rake surface 5 ^' , the curved surface of the hard material layer 3 corresponding to the cutting edge 6 ^' ) to the opposing surfaces of the substrate body (free surface 4, rake face 5, which is defined by the curved surface of the substrate body 3) corresponding to the cutting edge 6.

At this point it is expressly stated that the hard material layer 3 can also be deposited only on the cutting edge 6 or only on the cutting edge 6 and the free surface 4 or only on the cutting edge 6 and the rake surface 5.

In the detailed illustration of the cutting element 1 shown in FIG. 2 in a section in a sectional plane perpendicular to the cutting edge 6 and thus the cutting edge 6 ^' , the curved cutting edge 6 can be seen particularly well. Within a circular cutting edge section 8 of the cutting edge 6, which extends over the entire cutting edge 9 directly below the hard material layer 2, i.e. 100% thereof, a corresponding local radius of curvature 9 can be assigned to each point of the cutting edge section 8 (for the sake of clarity, only four radii of curvature are shown 9 shown). Since the cutting edge section 8 is circular, the radii of curvature 9 are equal. The cutting edge section 8 and thus the cutting edge 6 begin on the side of the flank 4 where it stops being flat, and on the side of the rake face 5 where it stops being flat. Accordingly, the cutting edge 6 ^' begins on the ^{side of the flank face 4'} where it ceases to be flat, and on the side of the rake face 5 ^' where it stops being flat. The cutting edge 6 ^' is thus also circularly curved, but with a larger radius of curvature at each point thereof.

The illustration in FIG. 3 corresponds to that in FIG. 2 with the difference that a wedge angle 7 is expressly shown, which the flank face 4 and the rake face 5 form with one another; the wedge angle 7 is 56 ° by way of example, but smaller or larger wedge angles are also conceivable. The bisector 10 of the wedge angle 7 penetrates the center of a circle 11, the center being defined by the radii of curvature 9.

Claims

EXPECTATIONS

1. Cutting element (1), which is designed for machining a non-metallic composite material from a matrix and particles held together by the matrix, having a free surface (4), a rake face (5) and a cutting edge (6) coated by an edge coating (2) , through which the flank face (4) and the rake face (5) are connected to one another, characterized in that the cutting edge (6) is curved within a cutting edge section (8) thereof in such a way that the cutting edge (2) immediately below the edge coating (2 ) in a section in a cutting plane which is perpendicular to the cutting edge (6), at each point of the cutting edge section (8) has a local radius of curvature (9) which is greater than or equal to 10 μm and less than or equal to 80 μm, preferably greater than or equal to is equal to 15 pm and less than or equal to 60 pm, even more preferably greater than or equal to 20 pm and less than or equal to 40 pm.

2. Cutting element (1) according to claim 1, characterized in that the cutting edge (6) is formed at least in the region of the cutting edge section (8) by a hard metal or cermet.

3. Cutting element (1) according to claim 2, characterized in that the cutting edge (6) is formed at least in the region of the cutting edge section (8) by a hard metal, wherein the hard metal has hard material particles, wherein the hard material particles form a skeleton structure of the hard metal and where the Hard material particles have a grain size in the range from 0.1 μm to 1.5 μm, preferably from 0.15 μm to 0.8 μm, even more preferably from 0.2 μm to 0.5 μm.

4. Cutting element (1) according to claim 1, characterized in that the cutting edge section (8) extends over at least 50%, preferably at least 70%, even more preferably at least 90%, of the cutting edge (6) in the section in the cutting plane.

5. Cutting element (1) according to claim 1 or 2, characterized in that a wedge angle (7) is defined in the section in the cutting plane by the flank (4) and the rake face (5), by a smallest radius of curvature (9) of the Radii of curvature (9) the position and the radius (9) of a circle (11) in the section in the Section plane is defined and a point is defined on an angle bisector (10) defined by the wedge angle (7) through the center of this circle (11).

6. Cutting element (1) according to one of the preceding claims, characterized in that the edge coating (2) is formed by at least one deposited hard material layer (2), where the edge coating (2) is formed on the cutting edge section (8).

7. Cutting element (1) according to one of the preceding claims, characterized in that the hard material layer (2) is formed by diamond, amorphous carbon, cubic boron nitride or TiB2.

8. Cutting element (1) according to one of the preceding claims, characterized in that the edge coating (2) is designed to extend onto the free surface (4) and / or onto the rake face (5).

9. Cutting element (1) according to one of the preceding claims, characterized in that a layer thickness of the edge coating (2) is greater than or equal to 0.5 pm and less than or equal to 20 pm, preferably greater than or equal to 5 pm and less than or 20 pm where the edge coating (2) is formed on the cutting edge portion (8).

10. Cutting element (1) according to one of the preceding claims, characterized in that the edge coating (2) is formed at least on the cutting edge section (8) by a PVD or a CVD deposition process.

11. Cutting element (1) according to one of the preceding claims, characterized in that it is formed on a drilling tool, milling tool or planing tool.

12. Cutting element (1) according to one of the preceding claims, characterized in that the particles are formed by particles from wood chips or wood fibers and the matrix is formed by an adhesive.

13. Use of a cutting element (1) according to one of claims 1 to 12 for machining the non-metallic composite material.

14. Use according to claim 13, wherein the particles are formed by wood chips or wood fibers and the matrix is formed by an adhesive.

15. Use according to claim 13 or 14, wherein the particles are formed by carbon fibers or glass fibers and the matrix is formed by a plastic.