Razor Blade
20200307006 ยท 2020-10-01
Inventors
- Labros KONTOKOSTAS (P.FALIRO ATHENS, GR)
- loannis PAPATRIANTAFYLLOU (MAROUSI ATHENS, GR)
- Taxiarchis Terlilis (Athens, GR)
- Anastasios Siozios (Marousi Athens, GR)
- Konstantinos Mavroeidis (Papagos Athens, GR)
Cpc classification
International classification
Abstract
A razor blade has a symmetrical tapering blade edge ending in a blade tip. The razor blade includes a substrate and a coating covering the substrate. The coating includes a soft coating and a hard coating. The hard coating includes at least a main layer. The soft coating covers the hard coating. The substrate has a substrate tip including a tapering geometry toward the substrate tip. The substrate tip has specific thicknesses at distances of 5 micrometers, 20 micrometers, 40 micrometers, and 200 micrometers from the substrate tip.
Claims
1. A razor blade having a symmetrical tapering blade edge ending in a substrate tip, the razor blade comprising: a substrate having a thickness of between 1.80 micrometers and 2.40 micrometers measured at a distance of 5 micrometers from the substrate tip, a thickness of between 6.2 micrometers and 7.70 micrometers measured at a distance of 20 micrometers from the substrate tip, a thickness (T40) of between 11.60 micrometers and 13.50 micrometers measured at a distance of 40 micrometers from the substrate tip, and a thickness of between 51 micrometers and 56 micrometers measured at a distance of 200 micrometers from the substrate tip.
2. The razor blade according to claim 1, wherein the razor blade further comprises at least one coating layer.
3. The razor blade according to claim 2, wherein the coating layer has an overall thickness of 10 nm to 500 nm.
4. The razor blade according to claim 2, wherein the coating layer has an overall thickness of 100 nm to 400 nm.
5. The razor blade according to claim 1, wherein the substrate has a thickness of between 9.00 micrometers and 10.50 micrometers measured at a distance of 30 micrometers from the substrate tip.
6. The razor blade according to claim 1, wherein the substrate has a thickness of between 14.50 micrometers and 16.50 micrometers measured at a distance of 50 micrometers from the substrate tip.
7. The razor blade according to claim 1, wherein the substrate has a thickness of between 27.50 micrometers and 31.50 micrometers measured at a distance of 100 micrometers from the substrate tip.
8. The razor blade according to claim 1, wherein the substrate has a thickness of between 41.00 micrometers and 46.00 micrometers measured at a distance of 150 micrometers from the substrate tip.
9. The razor blade according to claim 1, wherein the substrate has a thickness of between 61.00 micrometers and 66.00 micrometers measured at a distance of 250 micrometers from the substrate tip.
10. The razor blade according to claim 1, wherein the substrate has a thickness of between 71.00 micrometers and 76.00 micrometers measured at a distance of 300 micrometers from the substrate tip.
11. The razor blade according to claim 1, wherein the substrate has a thickness of between 80.00 micrometers and 86.00 micrometers measured at a distance of 350 micrometers from the substrate tip.
12. The razor blade according to claim 2, wherein the coating further includes a soft coating and a hard coating, wherein the hard coating includes an interlayer, the interlayer being located between the substrate and the hard coating, and an overcoat layer, the overcoat layer being located between the hard coating and the soft coating.
13. A razor head comprising: a housing and at least one razor blade according to claim 1.
14. A shaving device comprising: a razor handle and a razor head according to claim 13.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
[0040] Other characteristics and advantages will readily appear from the following description of the disclosed embodiments, provided as non-limitative examples, and of the accompanying drawings.
[0041] On the drawings:
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[0060] On the different Figures, the same reference signs designate like or similar elements.
DETAILED DESCRIPTION
[0061] The desired blade profile of the razor blade according to the description may be achieved by a grinding process that involves one, two, three or four grinding stations.
[0062] The disclosure is also believed to be applicable to razor blades with a substrate of carbon steel. Another possible material is ceramics. These materials are considered insofar as they are suitable for razor blade materials.
[0063] The metal strip is longer than a plurality of razor blades, for example it corresponds to 1000 to-be razor blades or more.
[0064] Before grinding, the metal strip 3 has, generally speaking, a rectangular cross-section. The height of the metal strip may be slightly over the height of one finished razor blade, or slightly over the height of two finished razor blades, if grinding is to be performed on both edges. The thickness of the metal strip is the maximum thickness of the future razor blades. The continuous strip 3 has for instance a thickness which can be comprised between 74 m and 100 m. The strip may pass through punches which enable to carry the strip along the installation 1 during the grinding process, and/or may be used to facilitate future separation of the individual razor blades from the strip.
[0065] As the metal strip 3 moves along the grinding stations 2a, 2b, it is sequentially subjected to a rough grinding, a semi-finishing and a finishing grinding operation. Depending on the number of stations involved, the rough grinding and semi-finishing operation may be performed separately or in the same station. Thereafter, a finishing grinding operation can be required. The grinding steps are performed continuously, in that the strip is moved continuously through the stations without stopping.
[0066] When the rough grinding is performed separately, one or two grinding stations are required. Each grinding station may utilize one or two abrading wheels that are positioned parallel with respect to the moving strip. When rough grinding is performed separately, one or two grinding stations required. Each grinding station may utilize one or two abrading wheels that positioned parallel with respect to the moving strip. The abrading wheels have uniform grit size along their length. They may also be full body, helically grooved or a consecutive disc pattern along their length. The material of the abrading wheels might comprise CBN (Cubic Boron Nitride), silicon carbide and aluminum oxide or diamond.
[0067] When rough grinding and semi-finishing operations performed simultaneously, a single grinding station is required. In this case the station includes two abrading wheels formed into spiral helixes or a consecutive disc pattern with a special profile. The rotational axes of these wheels may be parallel or positioned at an angle with respect to the moving strip. The tilt angle ranges between 0.5 and 5. The grit size of the wheels may also be uniform or progressively decreasing along their length towards the exit of the strip. The abrasive material of the wheels may be CBN (Cubic Boron Nitride), silicon carbide and aluminum oxide or diamond.
[0068] The finishing operation requires a single grinding station with 2 abrading wheels positioned at an angle with respect to the moving strip. The tilted angle ranges between 1 and 5.5.
[0069] The wheels form spiral helixes and are specially profiled as well. The abrasive material can be CBN (Cubic Boron Nitride), silicon carbide and aluminum oxide or diamond. The length of the wheel may also range between 3 to 8 inches (7.62 cm to 20.32 cm).
[0070] The process is tuned so as to obtain a symmetrical razor blade substrate 10 with a tapering geometry toward a substrate tip 14, as shown in
[0071] For the measurement of the blade geometry, surface roughness and grinded angle, a confocal microscope has been used. A typical example is shown on
[0072] As depicted schematically on
[0073] The confocal microscope has a given measurement field of, for example 200 m200 m. In the present example, a semi-transparent mirror 28 is used between the pinhole plate 22 and the lens 23 to direct the reflected light toward the CCD 25. In such case, another pinhole plate 27 is used for the filtering. However, in variant, the semi-transparent mirror 28 could be used between the light source and the pinhole plate 22, which would enable to use only one pinhole plate for both the emitted light signal and the reflected light signal.
[0074] The piezo-drive 24 is adapted to move the lens 23 along the light propagation axis, to change the position of the focal point in depth. The focal plane can be changed while keeping the dimensions of this measurement field.
[0075] To extend the measurement field (in particular in order to measure the blade edge further away from the tip), one could perform another measurement at another location, and the data resulting from all measurements can be stitched.
[0076] The other side of the blade can then be measured, simply by flipping the blade to the other side.
[0077] According to one example, one could use a confocal microscope based on the Confocal Multi Pinhole (CMP) technology.
[0078] The pinhole plate 22 has then a large number of holes arranged in a special pattern. The movement of the pinhole plate 22 enables seamless scanning of the entire surface of the sample within the image field and only the light from the focal plane reaches the CCD camera, with the intensity following the confocal curve. Thus, the confocal microscope is capable of high resolution in the nanometer range.
[0079] As depicted on
[0080] More precisely, when the blade substrate 10 has a sole facet, more precisely a single facet 12 on one side and a single facet 13 on the other side (see
[0081] When the blade substrate 10 has two facets, more precisely two facets 12 and 12 on one side and two facets 13 and 13 on the other side (see
[0082] When the blade substrate 10 has three facets, more precisely three facets 12, 12 and 12 on one side and three facets 13, 13 and 13 on the other side (see
[0083] Razor blades with various geometries have been manufactured, measured, and tested for shaving performance. Manufacture includes not only substrate sharpening by grinding, but also coatings as will be described below. For the shaving tests, only the grinding step was modified in order to generate various substrate geometries, the other process steps being kept equal.
[0084] The tests determined that the thinness of the edge tip may be defined by checking the thickness of control points located 5 micrometers and 20 micrometers from the substrate tip 14. Further, the strength of the edge tip can be defined by checking the thickness of control points located 20 micrometers and 200 micrometers from the substrate tip 14.
[0085] After intense testing, it was determined that suitable shaving effects were obtained for razor blades having a substrate 10 with the following features of Table 1.
TABLE-US-00001 TABLE 1 Total blade edge profile Distance X from the Lower thickness Upper thickness substrate tip 14 limit (m) of the limit (m) of the (m) substrate substrate 5 1.8 2.4 20 6.2 7.7 30 9.0 10.5 40 11.6 13.5 50 14.5 16.5 100 27.5 31.5 150 41.0 46.0 200 51.0 56.0 250 61.0 66.0 300 71.0 76.0 350 80.0 86.0
[0086] The above dimensions can be obtained through a dispersion of products manufactured using the same manufacturing process.
[0087] The blade has a smooth profile in between and beyond (both from and away from the tip) these control points.
[0088] The blade thickness increase rate (slope) from the tip up to the transition point should be continuously decreasing, making the blade edge easier to penetrate the hair leading to better comfort. The blade profile after the transition point (from 40 m to 350 m) should be lying in a specific range of values in order to support a geometrically smooth transition from the first 40 m to the unground part of the blade. In that region, the thickness increase rate is less than, or equal to, the increase rate at 40 m.
[0089] The blade edge profile generated by the rough grinding stage, typically covering an area between 50 m-350 m from the substrate tip 14, determines the material removal rate of the finishing operation. Generally, the finishing grinding stage is mainly called to smoothen out the excess surface roughness produced by rough grinding along with the final shaping of the blade edge profile. For optimal process efficiency, the material removal rate of finishing grinding wheel should be kept minimum but such that the induced surface roughness ranges between 0.005 m-0.040 m.
[0090] For example, the thickness of the aforementioned substrate profile can be described with the following equation Y=AX.sup.n+C.
[0091] One or more formulas can be applied one after the other to the portion of the blade extending from the substrate tip 14 to a transition point from which the substrate has an unground portion.
[0092] In one embodiment, the profile can be according to the equation Y=AX.sup.n+C with constants taken from Table 2 below:
TABLE-US-00002 TABLE 2 X (m) A n C [0, 150] 0.49 0.89 0 (150, 350] 0.2 1.00 12.4
[0093] In another embodiment, the profile can be according to the equation Y=AX.sup.n+C with constants taken from Table 3 below:
TABLE-US-00003 TABLE 3 X (m) A n C [0, 50] 0.45 0.91 0 (50, 150] 0.3 1 0.8 (150, 350] 0.19 1 17.3
[0094] The razor blade substrate 10 comprising the blade edge 11 can be made of stainless steel.
[0095] A suitable stainless steel can comprise mainly iron, and, in weight C: 0.40-0.80%; Si: 0.10-1.5%; Mn: 0.1-1.5%; Cr: 11.0-15.0%; and Mo: 0.0-5.0%.
[0096] Other stainless steels can be used within the disclosure. Other materials which are known as razor blade substrate materials can be considered.
[0097] The further manufacturing steps of a razor blade are described below.
[0098] After manufacturing the substrate according to the above-mentioned technique and with the distinct values of Tables 5-12, in a second step the substrates 10 (or grinded blades) are introduced into a deposition chamber in order to be coated. The above geometry measurements were performed before this coating is applied. The coating configuration may include one or more layers, which improve the properties of the protective coating, thus an interlayer, a main layer and a soft coating can be distinguished, respectively. The interlayer and the main layer define a hard coating. The hard coating may be covered by the soft coating. The coating layers enable to reduce the wear of the blade edge, improve the overall cutting properties and prolong the usability of the razor blade. The razor blade 9 covered by these several layers has still a profiled geometry and a tapering geometry with two coating sides converging toward a blade tip 14 (see
[0099] As the substrate 10 having a profiled geometry and a tapering geometry with two sides converging toward a substrate tip 14, the substrate 10 covered by the main layer 16 has a profiled geometry and a tapering geometry with two coating sides converging toward a hard coating tip 14. In addition, when provided with more than one facet 12, 13, for instance two facets 12, 12 and 13, 13 or three facets 12, 12, 12 and 13, 13, 13 the substrate 14 covered by the main layer 16 has still a profile with identical number of facets (one, two or three).
[0100] As depicted on
[0101] The strengthening coating 16 covering the substrate tip 14, has a profiled geometry and has a tapering geometry with two coating sides converging toward a hard coating tip 14. The assembly of the substrate 10 and the hard coating is designated by the expression coated-substrate 19.
[0102] On the embodiment depicted on
[0103] The strengthening coating layer 16 is used for its mechanical properties; and provides corrosion resistance and edge strengthening to the razor blade. The strengthening coating layer 16 may comprise Chromium (Cr), Chromium-Platinum (CrPt) mixtures, Chromium-Carbide (CrC) mixtures, diamond, diamond like carbon (DLC), nitrides, carbides, oxides and/or borides.
[0104] Besides, the hard coating may further comprise an interlayer (15). In that case, the blade edge 11 of the blade is covered by the interlayer 15 as depicted on
[0105] The interlayer 15 is implemented prior to the strengthening coating layer 16. Thus, the coating layer configuration of the blade edge 11 of the blade comprises an interlayer 15 covering the blade edge 11 of the blade and a strengthening coating layer 16 covering the interlayer 15. Such a covered blade has still a tapering geometry with two coating sides converging toward a hard coating tip 14.
[0106] Further, the strengthening coating layer 16 may be covered by an overcoat layer 20. The overcoat layer 20 is located between the main layer 16 and the soft coating 17.
[0107] The overcoat layer 20 also is thus covered by the soft coating which is a lubricating layer 17 which can be hydrophobic or hydrophilic, such as polyfluorocarbon, for example fluoropolymer, as shown on
[0108] The overcoat layer 20 is used to improve the adhesion of the polymeric film with the main layer. Corresponding materials that may be used to facilitate bonding of the lubricious coating to the main layer are Chromium (Cr), Titanium (Ti), Niobium (Nb), Molybdenum (Mo) or any alloy or any compound of them. In another embodiment titanium diboride can be used as an overcoat layer.
[0109] Finally, the deposition of the aforementioned layers, various Physical Vapor Deposition techniques can be implemented, such as Sputtering, RF-DC Magnetron Sputtering, Reactive Magnetron Sputtering, or Unbalance Magnetron Sputtering, E-Beam evaporation, Pulsed Laser deposition, cathodic arc deposition.
[0110] Hereafter is disclosed an example of coating procedure of a three-layer system which allows the manufacture of a razor blade according to the description. The hard coating comprises in that case the interlayer 15, the main layer 16 and the overcoat layer 20.
[0111] After loading a blade bayonets with the blade substrates on a rotating fixture, the chamber is put to a base pressure of 10.sup.5 Torr. Then Argon (Ar) gas is inserted into the chamber up to a pressure of 8 m Torr (8.10.sup.3 Torr). Rotation of the blade bayonets begins at a constant speed of 6 rpm and the targets are operated under DC current control at 0.2 A (Ampere). A DC voltage of 200 V-600 V (Volt) is applied on the stainless steel blades for 4 minutes in order to perform a sputter etching step. In another embodiment a Pulsed DC voltage of 100 V-600 V (Volt) is applied on the stainless steel blades for 4 minutes in order to perform a sputter etching step.
[0112] The deposition of the interlayer takes place after the end of sputter etching step, with the chamber pressure being adjusted to 3 m Torr. The interlayer target is operated under DC current control at 3 A-10 A (Ampere) while a DC voltage of 0 V-100 V (Volt) is applied on the rotating blades. Adjusting the deposition time, an interlayer of 5 nm-50 nm is deposited prior to the main layer. In one embodiment Ti can be the interlayer and in another one Cr can be the interlayer.
[0113] After the deposition of the interlayer, the current of the interlayer target is reduced to 0.2 A (Ampere) and the current of the main layer target(s) is increased to 3 A-6 A. A particular embodiment includes a TiB.sub.2 compound film of 10 nm-400 nm on top of the bonding interlayer. A DC bias voltage of 0 V-600 V is applied on the rotating blades.
[0114] Moreover, on top of the main layer, a Cr soft coating is deposited with the current on the Cr target(s) at 3 A and a bias voltage of 0 V-450 V. A particular Cr layer thickness is 5 nm-50 nm.
[0115] Finally, the overall coating thickness can vary from 10 to 500 nm and preferably from 10 nm to 250 nm on each blade edge facet.
[0116] The thicknesses of the razor blades according to the description are summarized in Table 13 according to the lower and higher coating thickness. The thickness of the razor blade 9, according to the disclosure, is measured at a distance X (in micrometers) from the hard coating tip 14. When the hard coating comprises an interlayer 15, a main layer 16 and an overcoat layer 20, then the thickness is measured at a distance X from the overcoat layer 20.
[0117] The thickness of the edge profile of the razor blade 9 is the sum of thickness of the edge profile of the uncoated blade (meaning the substrate) plus the thickness of the coating (i.e. the coted substrate). Finally, the overall coating thickness can vary from 10 to 500 nm and preferably from 100 nm to 400 nm on each blade edge facet.
TABLE-US-00004 TABLE 4 Distance X from the hard coating tip Lower thickness Upper thickness 14 (m) limit (m) limit (m) 5 1.81 2.9 20 6.21 8.2 30 9.01 11 40 11.61 14 50 14.51 17 100 27.51 32 150 41.01 46.5 200 51.01 56.5 250 61.01 66.5 300 71.01 76.5 350 80.01 86.5
[0118] The blade can be fixed or mechanically assembled to a razor head, and the razor head itself can be part of a razor. The blade can be movably mounted in a razor head and thus mounted on elastic fingers which urge it toward a rest position. The blade can be fixed, notably welded to a support 29, notably a metal support with a L-shaped cross-section, as shown in
[0119] Besides,
[0120] Although the preceding description has been described herein with reference to particular means, materials and embodiments, it is not intended to be limited to the particulars disclosed herein; rather, it extends to all functionally equivalent structures, methods and uses, such as are within the scope of the appended claims.