CUTTING ELEMENT WITH ASYMMETRIC CUTTING SEGMENTS

Abstract

The present invention relates to a cutting element having a substrate with at least one aperture which has a cutting edge along at least a portion of an inner perimeter of the aperture. The cutting edges have an asymmetric cross-sectional shape with a first face, a second face opposed to the first face and a cutting edge at the intersection of the first face and the second face. Moreover, the present invention relates to a hair removal device including such cutting elements.

Claims

1. A cutting element comprising a substrate with at least one aperture which comprises a cutting edge along at least a portion of a perimeter of the aperture, wherein the cutting edges have an asymmetric cross-sectional shape with a first face, a second face opposed to the first face and a cutting edge at the intersection of the first face and the second face, wherein: the first face comprises a first surface and a primary bevel with: the primary bevel extending from the cutting edge to the first surface, a first intersecting line connecting the primary bevel and the first surface, and a first wedge angle .sub.1 between an imaginary extension of the first surface and the primary bevel, and the second face comprises a secondary bevel and a tertiary bevel with: the secondary bevel extending from the cutting edge to the tertiary bevel, a second intersecting line connecting the secondary bevel and the tertiary bevel, a second wedge angle .sub.2 between the first surface and the secondary bevel, and a third wedge angle .sub.3 between the first surface and the tertiary bevel,
wherein .sub.1>.sub.2 and .sub.2.sub.3.

2. The cutting element of claim 1, wherein the substrate has a thickness of 20 to 1000 m, preferably 30 to 500 m, and more preferably 50 to 300 m.

3. The cutting element of claim 1, wherein the substrate comprises a first material or comprises a first material and a second material adjacent to the first material.

4. The cutting element of claim 3, wherein the first material comprises: metals, preferably titanium, nickel, chromium, niobium, tungsten, tantalum, molybdenum, vanadium, platinum, germanium, iron, and alloys thereof, in particular steel, ceramics comprising at least one element selected from the group consisting of carbon, nitrogen, boron, oxygen and combinations thereof, preferably silicon carbide, zirconium oxide, aluminum oxide, silicon nitride, boron nitride, tantalum nitride, TiAlN, TiCN, and/or TiB.sub.2, glass ceramics; preferably aluminum-containing glass-ceramics, composite materials made from ceramic materials in a metallic matrix (cermets), hard metals, preferably sintered carbide hard metals, such as tungsten carbide or titanium carbide bonded with cobalt or nickel, silicon or germanium, preferably with the crystalline plane parallel to the second face (2), wafer orientation <100>, <110>, <111>or <211>, single crystalline materials, glass or sapphire, polycrystalline or amorphous silicon or germanium, mono- or polycrystalline diamond, diamond like carbon (DLC), adamantine carbon, and combinations thereof.

5. The cutting element of any of claim 4, wherein the second material comprises a material selected from the group consisting of: oxides, nitrides, carbides, borides, preferably aluminum nitride, chromium nitride, titanium nitride, titanium carbon nitride, titanium aluminum nitride, cubic boron nitride, boron aluminum magnesium, carbon, preferably diamond, nano-crystalline diamond, diamond like carbon (DLC) like tetrahedral amorphous carbon, and combinations thereof.

6. The cutting element of claims 3, wherein the second material fulfills at least one of the following properties: a thickness of 0.15 to 20 m, preferably 2 to 15 m and more preferably 3 to 12 m, a modulus of elasticity of less than 1200 GPa, preferably less than 900 GPa, more preferably less than 750 GPa, and even more preferably 500 GPa, a transverse rupture stress .sub.0 of at least 1 GPa, preferably at least 2.5 GPa, more preferably at least 5 GPa, and a hardness of at least 20 GPa.

7. The cutting element of claim 3, wherein the material of the second material is nano-crystalline diamond and fulfills at least one of the following properties: an average surface roughness R.sub.RMS of less than 100 nm, less than 50 nm, more preferably less than 20 nm, an average grain size d.sub.50 of the fine-crystalline diamond of 1 to 100 nm, preferably from 5 to 90 nm, more preferably from 7 to 30 nm, and even more preferably 10 to 20 nm.

8. The cutting element of claim 3, wherein the first material and/or the second material are coated at least in regions with an low-friction material, preferably selected from the group consisting of fluoropolymer materials like PTFE, parylene, polyvinylpyrrolidone, polyethylene, polypropylene, polymethyl methacrylate, graphite, diamond-like carbon (DLC) and combinations thereof.

9. The cutting element of claim 3, wherein the first intersecting line is shaped in the second material and/or the second intersecting line is arranged at the boundary surface of the first material and the second material.

10. The cutting element of any of claim 1, wherein the at least one aperture has a form which is selected from the group consisting of circular, ellipsoidal, square, triangular, rectangular, trapezoidal, hexagonal, octagonal or combinations thereof, wherein it is preferred that the at least one aperture has an aperture area ranging from 0.2 mm.sup.2 to 25 mm.sup.2, preferably from 1 mm.sup.2 to 15 mm.sup.2, more preferably from 2 mm.sup.2 to 12 mm.sup.2.

11. The cutting element of any of claim 1, wherein the first wedge angle .sub.1 ranges from 5 to 75, preferably 10 to 60, more preferably 15 to 46, and even more preferably 20 to 45 and/or the second wedge angle .sub.2 ranges from 10 to 40, preferably 0 to 30, more preferably 10 to 25 and/or the third wedge angle .sub.3 ranges from 1 to 60, preferably 10 to 55, more preferably 19 to 46, and even more preferably 20 to 45.

12. The cutting element of claim 1, wherein the primary bevel has a length d.sub.1 being the dimension projected onto the first surface and/or the imaginary extension of the first surface taken from the cutting edge to the first intersecting line from 0.1 to 7 m, preferably from 0.5 to 5 m, more preferably 1 to 3 m and/or the dimension projected onto the first surface and/or the imaginary extension of the first surface taken from the cutting edge to the second intersecting line has a length d.sub.2 which ranges from 5 to 150 m, preferably from 10 to 100 m, and more preferably from to 80 m.

13. The cutting element of claim 1, wherein the cutting edge has a tip radius of less than 200 nm, preferably less than 100 nm and more preferably less than 50 nm.

14. The cutting element of claim 1, wherein the secondary bevel comprises a further beveled region extending from the cutting edge to a third intersecting line connecting the secondary bevel and the beveled region, the beveled region preferably having a fourth wedge angle .sub.4 between the first surface and the beveled region.

15. A hair removal device comprising the cutting element of claim 1.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0074] The present invention is further illustrated by the following figures which show specific embodiments according to the present invention. However, these specific embodiments shall not be interpreted in any limiting way with respect to the present invention as described in the claims and in the general part of the specification.

[0075] FIG. 1a is a perspective view of a cutting element in accordance with the present invention;

[0076] FIG. 1b is a top view of a cutting element in accordance with the present invention;

[0077] FIG. 1c is a perspective view onto the first face of a cutting element in accordance with the present invention;

[0078] FIG. 2 is a top view onto the second face of a cutting element in accordance with the present invention;

[0079] FIG. 3 is a perspective view of a cutting element in accordance with the present invention;

[0080] FIG. 4 is a top view onto the second surface of a cutting element in accordance with the present invention;

[0081] FIG. 5 is a cross-sectional view of a cutting element in accordance with the present invention;

[0082] FIG. 6 is another cross-sectional view of a cutting element in accordance with the present invention with a second material;

[0083] FIG. 7 is a cross-sectional view of a further cutting element in accordance with the present invention with an additional beveled region of the secondary bevel;

[0084] FIG. 8 is a cross-sectional view of a further cutting element in accordance with the present invention with an additional beveled region of the secondary bevel with a second material;

[0085] FIG. 9a shows a flow chart of the process for manufacturing the cutting elements;

[0086] FIG. 9b shows details of process step 10 of the flow chart of FIG. 9a;

[0087] FIG. 9c shows details of process step 11 of the flow chart of FIG. 9a;

[0088] FIG. 9d shows the shape of a cutting element of the present invention;

[0089] FIG. 10 is a schematic cross sectional view of the tip of the cutting edge showing the determination of the tip radius;

[0090] The following reference signs are used in the figures of the present application.

REFERENCE SIGN LIST

[0091] 1 cutting element [0092] 2 first face [0093] 3 second face [0094] 4, 4, 4, 4 cutting edges [0095] 5 secondary bevel [0096] 6 tertiary bevel [0097] 7 primary bevel [0098] 8 quaternary bevel [0099] 9 first surface [0100] 9 imaginary extension of the first surface [0101] 10 third intersecting line [0102] 11 second intersecting line [0103] 12 first intersecting line [0104] 15 element body [0105] 16 cutting wedge [0106] 18 first material [0107] 19 second material [0108] 20 boundary surface [0109] 22 substrate [0110] 60 tip bisecting line [0111] 61 perpendicular line [0112] 62 circle [0113] 65 construction point [0114] 66 construction point [0115] 67 construction point [0116] 71 straight portions of aperture [0117] 72 curved portion of aperture [0118] 73 first section [0119] 74 second section [0120] 75 linear cutting edge extension [0121] 76 tangent to cutting edge [0122] 77 cross-sectional line [0123] 78 cross-sectional line [0124] 260 bisecting line [0125] 430 aperture [0126] 431 inner perimeter of aperture [0127] 432 aperture area

DETAILED DESCRIPTION OF THE INVENTION

[0128] FIG. 1a shows a cutting element of the present invention in a perspective view. The cutting element with a first face 2 and second face 3 comprises a substrate 22 of a first material 18 with an aperture 430. At the first face 2 the substrate 22 has its first surface 9 with an inner perimeter 431 of the aperture 430. In this embodiment, the cutting edge is shaped along the inner perimeter 431 resulting in a circular cutting edge.

[0129] FIG. 1b is a top view on the second face 3 of the cutting element. The substrate 22 has an aperture 430 with an inner perimeter 431. The substrate comprises a first material 18 and a second material 19 (not visible in this perspective) wherein the cutting edge is shaped along the inner perimeter 431 and in the second material 19.

[0130] FIG. 1c is a perspective view onto the first face 2 of the cutting element which shows the second material 19 having an aperture with an inner perimeter 431.

[0131] FIG. 2 shows a cutting element of the present invention in a perspective view. The cutting element with a first face 2 and second face 3 comprises a substrate 22 of a first material 18 with an aperture 430 having the shape of an octagon. At the first face 2 the substrate 22 has its first surface 9 (not visible) with an inner perimeter 431 of the aperture 430. In this embodiment, the cutting edges 4, 4, 4, 4 are shaped only in portions of the inner perimeter 431, i.e. every second side of the octagon has a cutting edge.

[0132] In FIG. 3, a perspective view of the cutting blade according to the present invention is shown. This cutting blade 1 has a blade body 15 which comprises a first face 2 and a second face 3 which is opposed to the first face 2. At the intersection of the first face 2 and the second face 3 a cutting edge 4 is located. The cutting edge 4 has curved portions. The first face 2 comprises a plane first surface 9 and a primary bevel 7 while the second surface 3 is segmented in two bevels. The second face 3 comprises a secondary bevel 5 and a tertiary bevel 6. The primary bevel 7 is connected via a first intersecting line 12 with the first surface 9. The secondary bevel 5 is connected to the tertiary bevel 6 via a second intersecting line 11.

[0133] FIG. 4 is a top view onto the second surface of a cutting element and illustrates what is meant by the cross-section within the scope of the present invention. The substrate 22 has an aperture 430 shaped with a cutting edge 16 with two straight portions 70, 71 and one curved portion 72 where the cutting edges are shaped. In the first section 74 of the straight portion 71 the slice goes through the substrate 22 perpendicular to the linear cutting-edge extension 75 corresponding to the cross-sectional line 78. In the second section 73 of the curved portion 72 the slice goes through the substrate 22 perpendicular to the tangent of the cutting edge 76 corresponding to the cross-sectional line 77.

[0134] In FIG. 5, a cross-sectional view of the cutting blade according to FIG. 3 is shown. The cutting blade 1 has a first face 2 with a primary bevel 7, a secondary bevel 5 and a tertiary bevel 6. The first face 2 comprises a planar first surface 9 and a primary bevel 7 connected by the first intersecting line (12). The primary bevel 7 has a first wedge angle .sub.1 between the imaginary extension of the first surface 9 and the primary bevel 7 while the second face 3 is segmented in two bevels, i.e., a secondary bevel 5 with a second wedge angle .sub.2 between the first surface 9 and the secondary bevel 5 with a bisecting line 260 of the secondary wedge angle .sub.2. The tertiary bevel 6 has a third wedge angle .sub.3 between the first surface 9 and the tertiary bevel 6 which is larger than .sub.2. The tertiary bevel 6 has a third wedge angle .sub.3 which is larger than .sub.2. The primary bevel 7 has a length d.sub.1 being the dimension projected onto the imaginary extension of the first surface 9 which is in the range from 0.1 to 7 m. The secondary bevel 5 has a length d.sub.2 being the dimension projected onto the first surface 9 and the imaginary extension of the first surface 9 which is in the range from 5 to 150 m, preferably from 10 to 100 m, and more preferably from 20 to 80 m.

[0135] In FIG. 6, a further cross-sectional view of a cutting element of the present invention is shown which corresponds largely with the embodiment of FIG. 5. The main difference is that the element body 15 comprises a first material 18, and a second material 19 joined with the first material 18, wherein the first material 18 e.g., is silicon and the second material 19 e.g. is a diamond layer. The primary bevel 7 and secondary bevel 5 are located in the second material 19 while the tertiary bevel 6 is located in the first material 18. The first material 18 and the second material 19 are separated by a boundary surface 20 which ends up with the second intersecting line 11.

[0136] In FIG. 7, a cross-sectional view of a further cutting element according to the present invention is shown. The cutting element 1 has an element body 15 which comprises a first face 2 and a second face 3 which is opposed to the first face 2. The first face 2 comprises a first surface 9 and a primary bevel 7 having a length d.sub.1. The second face 3 comprises a secondary bevel 5 and a tertiary bevel 6. The secondary bevel 5 is connected to the tertiary bevel 6 via a second intersecting line 11. Moreover, the second bevel 5 comprises a beveled region 8 which extends from the second intersecting line 10 to the cutting edge 4. The cutting edge 4 is located in the intersection of primary bevel 7 and the beveled region 8 of the secondary bevel 5. The length d.sub.1 of the primary bevel 7 and the wedge angle .sub.1 define the distance of the cutting edge 4 to the object to be cut in the case that the object to be cut is on the first face 2.

[0137] FIG. 8 shows a further sectional view of the cutting element of the present invention which corresponds largely with the embodiment of FIG. 7. However, the embodiment of FIG. 8 has an element body 15 which comprises a first material 18 and a second material 19. The primary bevel 7, the secondary bevel 5 and the beveled region 8 are all located in the second material 19 while the tertiary bevel 6 is located in the first material 18. The first material 18 and the second material 19 are joined along a boundary surface 20 which ends up with the second intersecting line 11.

[0138] In FIG. 9a a flow chart of the inventive process is shown. In a first step 1, a silicon wafer 101 is coated by PE-CVD or thermal treatment (low pressure CVD) with a silicon nitride (Si.sub.3N.sub.4) layer 102 as protection layer for the silicon. The layer thickness and deposition procedure must be chosen carefully to enable sufficient chemical stability to withstand the following etching steps. In step 2, a photoresist 103 is deposited onto the Si.sub.3N.sub.4 coated substrate and subsequently patterned by photolithography. The (Si.sub.3N.sub.4) layer is then structured by e.g., CF.sub.4-plasma reactive ion etching (RIE) using the patterned photoresist as mask. After patterning, the photoresist 103 is stripped by organic solvents in step 3. The remaining, patterned Si.sub.3N.sub.4 layer 102 serves as a mask for the following pre-structuring step 4 of the silicon wafer 101 e.g., by anisotropic wet chemical etching in KOH. The etching process is ended when the structures on the second face 3 have reached a predetermined depth and a continuous silicon first face 2 remains. Other wet- and dry chemical processes may be suited, e.g., isotropic wet chemical etching in HF/HNO.sub.3 solutions or the application of fluorine containing plasmas. In the following step 5, the remaining Si.sub.3N.sub.4 is removed by, e.g., hydrofluoric acid (HF) or fluorine plasma treatment. In step 6, the pre-structured Si-substrate is coated with an approx. 10 m thin diamond layer 104, e.g., nano-crystalline diamond. The diamond layer 104 can be deposited onto the pre-structured second surface 3 and the continuous first surface 2 of the Si-wafer 101 (as shown in step 6) or only on the continuous first surface 2 of the Si-wafer (not shown here). In the case of double-sided coating, the diamond layer 104 on the structured second surface 3 has to be removed in a further step 7 prior to the following edge formation steps 9-11 of the cutting element. The selective removal of the diamond layer 104 is performed e.g., by using an Ar/O.sub.2-plasma (e.g. RIE or ICP mode), which shows a high selectivity towards the silicon substrate. In step 8, the silicon wafer 101 is thinned so that the diamond layer 104 is partially free standing without substrate material and the desired substrate thickness is achieved in the remaining regions. This step can be performed by wet chemical etching in KOH or HF/HNO.sub.3 etchants or preferably by plasma etching in CF.sub.4, SF.sub.6, or CHF.sub.3 containing plasmas in RIE or ICP mode.

[0139] In a next step 9, the diamond film is etched anisotropically by an Ar/O.sub.2-plasma in an RIE system to form an almost vertical bevel 5 with a 90 corner in the diamond layer 104, which is required to form the primary bevel 7 on the first face 2 of the cutting element as shown in step 10.

[0140] To form primary bevel 7 on the first face 2 of the cutting element, the Si-wafer 101 is now turned to expose the first face 2 to the subsequent etching step 10 (FIG. 9b). By utilizing a physical enriched anisotropic RIE process in Ar/O.sub.2-plasma the 90 corner 5 is chamfered to form primary bevel 7. Process details are disclosed for instance in EP 2 727 880.

[0141] Finally, in step 11 (FIG. 9c) the cutting edge formation is completed by processing the Si-wafer 101 on the second face 3 to form secondary bevel 5 as shown in FIG. 9d. Multiple bevels may be formed by varying the process parameters. Process details are disclosed for instance in DE 198 59 905 A1.

[0142] In FIG. 10, it is shown how the tip radius can be determined. The tip radius is determined by first drawing a tip bisecting line 60 bisecting the cross-sectional image of the first bevel of the cutting edge 1 in half. Where the tip bisecting line 60 bisects the first bevel point 65 is drawn. A second line 61 is drawn perpendicular to line 60 at a distance of 110 nm from point 65. Where line 61 bisects the first bevel two additional points 66 and 67 are drawn. A circle 62 is then constructed from points 65, 66 and 67. The radius of circle 62 is the tip radius for coated cutting element 1.

[0143] The dimensions and values disclosed herein are not to be understood as being strictly limited to the exact numerical values recited. Instead, unless otherwise specified, each such dimension is intended to mean both the recited value and a functionally equivalent range surrounding that value. For example, a dimension disclosed as 40 mm is intended to mean about 40 mm.

[0144] Every document cited herein, including any cross referenced or related patent or application and any patent application or patent to which this application claims priority or benefit thereof, is hereby incorporated herein by reference in its entirety unless expressly excluded or otherwise limited. The citation of any document is not an admission that it is prior art with respect to any invention disclosed or claimed herein or that it alone, or in any combination with any other reference or references, teaches, suggests, or discloses any such invention. Further, to the extent that any meaning or definition of a term in this document conflicts with any meaning or definition of the same term in a document incorporated by reference, the meaning or definition assigned to that term in this document shall govern.

[0145] While particular embodiments of the present invention have been illustrated and described, it would be obvious to those skilled in the art that various other changes and modifications can be made without departing from the spirit and scope of the invention. It is therefore intended to cover in the appended claims all such changes and modifications that are within the scope of this invention.