Title of Invention

"A BLADE FOR A SHAVING RAZOR AND RAZOR BLADE CARTRIDGE INCORPORATING SAID BLADE"

Abstract

A strengthened blade for a shaving razor including a generally flat blade member having a vddth along a width axis, a length along a transverse length axis, and smaller dimensions along a thickness axis that; is normal to both the width axis and the length axis; the* .blade member having a nonlinear front cutting edge defined by a plurality of ws.ves having crests and valleys extending above and below the length axis in a direction that is parallel to the thickness axis.

Full Text

The present invention relates to a blade for a shaving razor and razor blade cartridge incorporating said blade. Razor blade cartridges typically include plastic housings that are attached to or made integral with a handle and have one or more fixed or movable razor blades mounted on the housing. The housing typically includes a guard / structure in front of the blades that engages and stretches the skin in front of the blades and a cap structure behind the blades that slides over the skin. On razors, the blade tangent angle for a blade is defined as the angle made by a line drawn through the central longitudinal axis of the blade cross section and extending from the cutting edge of the blade, and a tangent line drawn between the top surfaces of the structures contacted by the skin immediately in front of the cutting edge and the tip of the cutting edge. Blade exposure is defined as the distance of the cutting edge above or below a tangent line drawn between the top surfaces of the structures in front of and behind the cutting edge; the distance is measured normal to the tangent line. Razor blades are typically sharpened and processed to provide the desired shape and hardness prior to mounting on the housing. In one type of razor design, flat razor blade members having straight cutting edges are supported on L-shaped supports that are resiliently mounted on the housing. In designing razor blade cartridges, it is desirable to provide a close shave while avoiding nicks and cuts byadjusting such parameters ae blade sharpness, blade tangent angle, and exposure, slicing cuts typically occur when a. straight cutting edge is inadvertently moved sideways (i.e., transverse to the usual upward or downward motion oil the razor) on the skin such that: the straight razor edge slices into the skin. This sideways movement can cause the"blade edge to act as a knife cutting cleanly through the skin. It is also desirable to provide general shaving comfort and overall performance. It 'is also desirable tea have a blade edge that has sufficient strength to survive . the rigors of shaving and to provide confidence to the razor blade designer that the blade edge will not distort or deflect owing to the shaving forces applied to the blade edge. . Summary of the Inveritioa In one aspect, the invention features, in general, a blade for a shaving razor that has a nonlinear front cutting edge that is defined by a-plurality of waves having crests and valleys extending above and below a transverse length axis. The nonlinear cutting edge is provided on a blade member that is generally flat and. has a width along a width axis, a length along a transverse length axis, and smaller dimensions along a thickness axis defined normal to both the length and width axes. The non-linear front cutting edge generally extends along the length axis, and the waves extend above and below the length axis in &• direction that is parallel to the thickness axis. Certain implementations of the invention may include one or more of the following features. In certain implementations, the blade includes an "L-Bhaped" support under the blade member? the support is thicker than the blade member, and includes an upper portion to which the blade member ia attached and an extension extending downward therefrom; the upper portion haa a plurality of waves that are aligned with the waves of the blade member. The blade member has a length of between 1 and 2 inches, and has between 2 and 24 waves {moat preferably between 6 and 18 waves), .The waves have an amplitude between crests and valleys of less than 0,012", preferably between 0.002" and 0.004", and most preferably about 0.003". The blade metriber is made of metal between about 0.002" and about 0.010" thick, preferably "between about 0.003" and about o;004" thick. The waves have an amplitude of distance between the crests cind valleys that is between 50!fe and 15,0% of the thickness of the metal, most preferably between 75% and 125% of the thickness. The waves preferably extend throughout the width of the blade member. in another aspect, the invention features, in general, a blade with a wavy blade member as has already-been generally described, the waves having an amplitude of distance between crests and valleys selected, to be greater than an amplitude that causes unnecessary cuts in .the skin if the cutting edge is slid sideways on the skin and to be less than an anplitude that causes a decrease in shaving comfort when compared to'a linear front cutting edge. Preferably the waves have an amplitude between crests £.nd valleys of greater than 0.001" and less than" o.012", most preferably between 0.002" and 0,004". In another aspect, the invention features, in general, a blade with a strengthened wavy blade, member as has already been generally described, the strengthened blade member having a moment of: inertia that is at least 20% greater (preferably at least 35% greater) than n mument o£ inertia for a flat, linear edged, blade member made of material having the same thickness as the strengthened blade member with wavea. In another aspect, the invention features, in general, a razor blade cartridge including a housing and a blade with a nonlinear, wavy front cutting edge as has already been generally described. Certain implementations of the invention may include . one or more of the following features,. In certain implementations, the cartridge has a plurality of blades, .and the waves in one blade member preferably are aligned with the wavea in another blade member. The housing has connecting structure for connection to a handle and pivoting structure providing pivoting of the housing with respect to the handle. The connecting structure and the pivoting structure are provided by a structure that provides a . pivotal connection between the cartridge and the handle. In some implementations the blade members are mounted on an. upper portion oii an "L-shaped" support that also has a downward extension that, is elidably mounted within a slot in the housing, the upper portion having waves aligned with the waves in the blade member. In some other implementations blade (s) may be fixedly mounted on a platform portion of: the housing, and may be separated by a spacer. In another aspect, the invention features, in general, a method of making a blade that includes sharpening a generally flat blade member to form a linear cutting edge that extends along a length axis, and thereafter deforming the1 blade membeir to cause' a nonlinear, wavy front cutting edge as has already been generally described. Certain implementations of the invention may include one or more of the following features. In certain implementations, the blade member is mounted on a portion of a support prior to the deforming step, and both the blside member and the portion of the support underneath the blade member are deformed. The blade member is preferably mounted on the support by spot welda located at: valleys or crests; (preferably valleys) of the waves. The deforming includes bending between opposed dies that preferably have nonmatching surfaces so as to provide regions for material flow of the blade member and the support portion thereunder during deforming. The.dies have surfaces that cause three-point or four-point bending of the blade member and the support portion thereunder. Embodiments of the invention may include on« or more of the following advantages. The provision of waves in the cutting edge of the blade can avoid "slash" cuts that occur when a blade is accidentally side-slipped along the cutting edge (length) axis.- Since the non-linear blade edge has an undulating edge, the edge, when it side slips, merely "scrapes11 across the skin without slicing into the skin. In addition, hairs being cut can be subjected, in successive strokes, to different portions of the blade having different blade tangent angles, potentially providing for a closer cutting of hairs with varying orientation. The wavy nature of the blade,may provide for better skin engagement and skin-stretching, and, in the case of a two or three blade system, the first blzide functions as a front guard for a blade behind :i.t. The wavy nature'of the blade and/or.its support additionally strengthens the blade structure and promotes blade etiffnesia. reducing uncontrolled blade edge flexure which may cause unpredictable or variable blade contact angles and/or exposure with the surface of the skin. Other advantages and features of the invention will be apparent from the following description of the preferred embodiments thereof and from the claims. The present invention relates to a blade for a shaving razor having a xv •gfencraHy flat blade member a width along a width axis, a length along a transverse length axis, and smaller dimensions along a thickness axis that is normal to both of said width axis and said length axis, said blade member having a permanently formed nonlinear front cutting edge that genergHy extends along said length axis and is defined by a plurality of permanently formed waves having gently curving crests and valleys extending above and below said length axis in a direction that is parallel to said thickness axis, characterized in that said nonlinear front cutting edge is located in a plane that is parallel to said thickness axis, said blade member having an elastic limit and being deformed beyond said elastic limit with an applied force to create said nonlinear cutting edge and said waves such that the blade member has a shape and maintains said shape in the absence of said applied force, whereby said blade provides a variable blade tangent angle along said cutting edge. The present invention also relates to a razor blade cartridge incorporating the above-mentioned blade, characterized in that said cartridge has a housing having a guard and in that said blade is mounted on said housing behind said guard. BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS Fig. 1 is a perspective view of a razor blade. Fig. 2 is a plan view of the Fig. 1 blade. Fig. 3 is a partial elevation of the Fig. I blade. Fig. 4 is a vertical, sectional view of the Fig. l blade prior to bending. Fig. 5 is a vertical, sectional view of a razor blade cartridge including two blades as shown in Fig. 1. Fig. 6 is a vertical, sectional view of an alternative razor blade cartridge including an alternative razor blade. Fig. 7 is a diagram showing a press and fixturing system used to provide waves in the Fig. 1 blade. Fig. 8 is a partial elevation showing the die portions for providing three-point bending in the Fig. 7 system. Fig. 9 is a partial elevation showing the die portions for providing four-point bending in -the Fig. 7 system. Fig. 10 is a graph (not drawn to scale) showing the height of a blade member versus length for a single wave of a hypothetical blade member having waves that follow a sine curve. Fig. 11 is a front view showing the alignment of valleys and crests of waves of cutting edges in front and back blades of the Fig. 5 cartridge. Fig. 12 is an front elevation of the blade member of the Fig. 1 blade. Description of the Preferred Embodiments. Referring to Pigs. 1-3, there is shown razor blade 10 including blade member 12 and angled support 14. Blade member 12 is generally flat and has a width along width axis W, a length along transverse length axis L, and smaller dimensions along thickness axis T that: is normal to width axis W and length axis L. Support 14 has upper portion 16 to which blade member 12 is preferably attached by thirteen spot welds 18. Support 14 also has elongated extension 20 thereunder. Blade member 12 has a nonlinear front .cutting edge 13 "that generally extends along-length axis L and preferably is defined by twelve waves 15 having crests and valleys extending above and below length axis L in a direction that is parallel to thickness axis T. Waves IS extend rearward from front cutting edge 13 parallel to each other preferably over the entire width of blade member 12. Upper portion 16 has twelve waves! 17 corresponding to s.nd aligned with waves 15. The valleys o£ the,waves occur at spot welds 18. Waves 15, 17 are smooth and have crest to valley amplitudes below 0,012", preferably between 0.002" and 0.004", and most preferably about 0.003". The amplitude of 0.003" is believed to be sufficiently high to provide good protection against "slash" sideways cuts but not so high as to causse undue discomfort or irritation and propensity to cause nicks and cuts during normal up and down shaving strokes. Th« amplitude also yields acceptable overall shaving comfort values as compa.red to flat; blades based upon shave testa and accepted statistical analysis. It is believed that a value of crest to valley amplitude greater than 0.001" provides a minimum level of protection against sideways slash cuts and that veilues above 0.012" will result in undue irritation. As shown in Fig. 3, there is a slight: gap 19 between blade member 12 and upper portion 16 owing to spot welds 18 therebetween, Fig. 4 ahows undeformed blade 10' including flat blade member 12' and support 14' prior to forming, Blade member 13' is preferably made of 0.003" or 0.004" thick razor blade quality stainless steel which is martens"itic and has a uniform thickness section with a, width "d" of about 0.033" and a sharpened, portion extending in front for a dimension "c" of about 0.012". Upper portion 16' preferably has a dimension "b" of 0.0325". Support 14' is made of 0.011" thick staiinless steel. Extension 20' of support 14' extends downward from upper platform 16 a distance of O.OS96", Referring to Fig. S, razor blade cartridge 22 has housing 24 with arcuate surface 26 for providing a pivotal shell type bearing connection to a razor handle (not shown). Housing 24 supports two movable blades 10 in respective slots 25 in the side walls of the housing. Blades 10 are biased upward to the positions shown in Fig.- 5 by spring members 28. The create 80 and valleys 82 of cutting edge 13 Of the first blade 10 are preferably aligned with the crests 80 and valleys 82 of the cutting edg« of the second blade 10 in order to avoid regions of excessive exposure that could cause undue nicking (see Pig. 11) . Cartridge 22 also has flexible fin guard member 30 in front of the blades and lubricating strip 32 at cap section, 34. U.S. Patent No. 4,498,357, which is hereby incorporated by'reference, describes such a moving-blade cartridge design. Referring to Fig, 6, alternative razor blade cartridge 40 includes two fixed blades 42 on sandwiched platform support 44. cartridge 4Q also has guard member 46 and cap member 48. Blades 42 have waves of the same shape and amplitude as blade member 12, iarid the crests and valleys of the two blades are aligned. U.S. Patent No. 4,025,016, which is hereby incorporated by reference, describes such a fixed blade, cartridge design. In manufacture, blade member 12' is preferably sharpened/ coated, and sintered according to techniques well-known in the industry to obtain undeformed blade 10' as shown.in Fig. 4. E.g., U.S. Patents Nos. 3,652,443; 3,761,374; and 3,829,969, which ar« hereby incorporated by reference, describe such techniques. The blade member 12' .is preferably secured to support upper portion 16' by laser spot welding, as described in U.S. Patent No. 4|3'79,219, incorporated by reference herein. Referring to Figs, 7-9, an undeformed blade 10' ie formed in apparatus 49 between upper die 52 and lower die SO to provide waves 15 and 17 (Pig. 3), Portion 16' o£ support 14' (Fig. 4) is supported on lower die 50. Upper die 52 is moved downward toward and contacts blade member 12' . With continued downward movement, of upper die 52 toward lower die 50, blade member 12' and upper portion 16' are deformed, resulting in waves 15 and 17 extending throughout the width of blade member 12' and the underlying area of upper portion 16', respectively. Upper die 52 continues downward until it reaches stop 54,, which determines the amount of maximum deflection of blade member 12' and upper portion 16' . Upper die 52 is then raised, and blade 10' elastic.ally rejturnm to approximately 50% of the maximum deflected value. Thus, a maximum die deflection of amplitude of about ±0.00:3", which corresponds to a crest to valley amplitude;of about 0.006", results in a preferable final crest to valley wave amplitude of about. 0,003". Opposed dies 50 and 52 have nonmatching surfaces so as to provide regions for material flow during forming of undeformed blade member 12' and xmdeformed upper support portion 16' into formed blade member 12 and formed upper support portion 3.6. Tn particular, referring to Pigs. 8 and. 9, upper die 52 is used with lower die SO (Fig. 8) ilor three-point bending, and upper die 52 is used with Lower die 50' (Fig. 9) for four-point bending. Three-point or four-point bending ie used to permit material flow during1 the deflection and deformation process and to permit forming of upper portion 16' while extension 20' remains flat. In both cases, upper die 52 has thirteen semi'-circular ridges 56 with center-ta-center spacing of 0.119", a depth "e" of 0.0453", a radius 72 of 0.0315", and a small flatter central portion 58 of radius 73 of 0.069" having an arc segment length of about 0.001". Lower die 50 (Fig. B) has twelve circular ridges 60 with center-to-center spacing of 0.119", a depth "f" of 0.0358", a radius 74 of 0,0596", and a flat space"g" between ridges of Q.009S". Lower die 50' (Fig. 9) has 24 ridges 62 having center-to-center spacing of 0.595", a depth 75 of 0.0178", a radius 76 of 0.0298", a small flatter area 64 with a radius 77 of 0.0 535 "having an arc segment length of about 0.001", a flat spacing between ridges "h" of 0,0048", and a base dimension "i" of 0.0547". Ridges 36, 60, and 62 extend parallel to each other over a distance at least as long as the width of blade member 12' . In the three-point bending of Fig, !3, the three contact points for bending the waves in the blade edge for each wave are provided by an upper ridge 56 and the two lower ridges 60 on both sides. In the four-point bending of Fig. 8, the four points of contact for forming each wave are provided by two upper ridges 56 and the two lower ridges 62 between them. In both types of bending, spot welda 18 ar« located in the valleys under semicircular ridges 56 in order to provide better control of the amplitude of deflection and to provide for a stiffer structure. Referring to Fig. 12, in the current preferred system, the distance 70 between succesasive wave crssita is set at 0.119", and the preferred crest to valley wave amplitude is about 0.003". With three point bending (Fig. S) , the resulting non-linear wave edge has a wave crest radius Ri of slightly more than the 0.0596" radius 74 of ridge 60 and a wave valley radius R2 of slightly more -than the 0.0315" radius 72 of ridge 56,. owing to the release c£ the defected blade member after the maximum die deflection. Because the radius of ridge SO is about twice the radius of ridge 56, the resulting crests and valleys have a ratio R1/R2 of about 2:1. With the four point bending of Fig. 9, the formation of a single wave crest around two ridges 62 results in. approximately the same creet radius Rl; approximately the same valley rad:.us,R2 is caused by ridges 56. Thus, four-point bending with the apparatus of; Fig. 9 also results in a ratio R1/R2 of about 2:1. The crests and valleys could also have a ratio R1/R2 of about iti (thiei can be described by a sine wave) or of about 1:2.. Preferably the ratio R1/R2 is between 0.5 and 2, Four-point bending is preferred over three-point bending. Blades 3.0 (Fig. 5) and blades 42 (Fig.- 6) are formed using similar dies. When thte resulting blades are mounted on a housing, they have varying blade tangent angles along' their lengths. During shaving, with successive strokes over the same skin area, different: portions along the length of blade 10 or 42 will engage the same hair, By subjecting the hair to blade portions having different blade tangent angles, closer shaving can result. The use of waves in the blade can avoid "slash" cuts that occur whe:a a blade ia accidentally side-slipped along the cutting edge axis; slash.cuts can be problems with women shavers in particular. The wavy nature of a blade can also provide for better skin flow management, and the first b.'Lade can act as a better guard for the second blade behind it in two or three blade systems. This is because the effective contact length with a wavy cutting edge on the skin ia substantially longer than with a flat blade, thus providing more points of contact in stretching the akin. The wave. (Formula Removed) where: f = 1/2 the crest to valley wave amplitude, 1 - wavelength, arid h = blade thickness. The moment of inertia, IM(, for the wavy blade can be calculated as follows: (Formula Removed) The moment of inertia for a flat sheet (without waves') Cctn be calculated as follows: (Formula Removed) The change in moment of inertia, and thus the additional blade stiffness, caused by forming the waves in an initially flat blade is given by the following formula? (Formula Removed) The ratio of the moment of inertia for a wavy blade to the moment of inertia for a flat blade isgiven by the following formula; (Formula Removed) These formulas were xised to calculate 'the moments of inertia for a wavy blade member (having a .crest to valley amplitude of 0.003") and a flat blade member (used as a control) for I two thicknesses, 0.003" and Of.004", The results of the i moment of inertia calculations, the ratio of the mordent of inertia for a wavy blade member to that for the flat; blade member, and the % increase of moment of inertia of the wavy blade menber over that of the flat blade member are presented below in Table I, TABLE 1 (Table Removed) Prom the above table it is seen that the moment of inertia for a, wavy blade of- 0.004" thickness increases 34.4% over that of a flat blade of the same thickness, and for a wavy blade of 0.003" thickness the moment of inertia increase is 150%. It thus appears that the added, stiffness ' provided by the: wave shape: ban bo particularly significant for blade membesrs made of the thinner 0.003" thick metal. In multiple blade systems (such as shown in Fig. 5 or Fig. 6), it is preferable to'align the crests 80 and. valleys 82 of the first blade with the crests 83 and valleys 84 of the second blade, respectively,, as shown in Fig. 11. Other embodiments o£ the invention are within the scope of th« appended claims. E.g., the waves could b« provided at only the front j portion of blade member 12, and, instead of extending parallel to each other perpendicular to the front cutting edge, the waves could alternately converge and diverge as they extend rearward from the front edge. AlBO, in multiple blade systems, the crests and valleys can be unaligned with one another. WE CLAIM: 1. A blade (10) for a shaving razor having a generally flat blade member (12) a width along a width axis, a length along a transverse length axis, and smaller dimensions along a thickness axis that is normal to both of said width axis and said length axis, said blade member (12) having a permanently formed nonlinear front cutting edge that geaeraily extends along said length axis and is defined by a plurality of permanently formed waves (15) having gently curving crests (80) and valleys (82) extending above and below said length axis in a direction that is parallel to said thickness axis, characterized in that said nonlinear front cutting edge is located in a plane that is parallel to said thickness axis, said blade member having an elastic limit and being deformed beyond said elastic limit with an applied force to create said nonlinear cutting edge and said waves such that the blade member has a shape and maintains said shape in the absence of said applied force, whereby said blade provides a variable blade tangent angle along said cutting edge. 2. A blade as claimed in claim 1, wherein the blade member is attached to a support (14) under said blade member, said support having an upper portion (16) to which said blade member is attached and an extension (20) extending downward therefrom, said upper portion having a plurality of waves (17) aligned with said plurality of waves (15) of said blade member. 3. A blade as claimed in claim 1, wherein the waves have an amplitude of distance between said crests and valleys selected to be greater than an amplitude that causes unnecessary cuts in the skin if the cutting edge is slid sideways on the skin and to be less than an amplitude that causes a decrease in shaving comfort when compared to a linear front cutting edge. 4. A blade as claimed in claim 1, wherein said blade member has a length of between 2.54 cm (1") and 5.08 cm (2") and has between 2 and 24 of said waves. 5. A blade as claimed in claim 4, wherein said blade member has between 6 and 18 of said waves. 6. A blade as claimed in claim 1, wherein said waves have an amplitude of distance between said crests and valleys of less than 0.031 cm (0.012"). 7. A blade as claimed in claim 6, wherein said waves have an amplitude of distance between said crests and valleys of between 0.005 cm(0(O,OO2") and 0.010 cm (0.004"). 8. A blade as claimed in claim 1, wherein said blade member is made of metal having a thickness and said waves having an amplitude of distance between said crests and valleys that is between 50% and 150% of said thickness. 9. A blade as claimed in claim 8, wherein said waves have an amplitude of distance between said crests and valleys that is between 75% and 15% of said thickness. 10. A blade as claimed in claim 1, wherein said waves extend through the width of said blade member. 11. A blade as claimed in claim 1, wherein said blade member is made of metal between 0.005 cm (0.002") and 0.025 cm (0.010") thick. 12. A blade as claimed in claim 10, wherein said blade member is made of metal between 0.008 cm (O.003") and 0.010 cm (0.004") thick. 13. A blade as claimed in claim 2, wherein said blade member is spot welded to said support, and in that said wave valleys are aligned with said spot welds (18). 14. A razor blade cartridge (22) incorporating a blade as claimed in claim 1, wherein said cartridge (22) has a housing (24) having a guard (30) and in that said blade (10) is mounted on said housing (24) behind said guard (30). 15. A cartridge as claimed in claim 14, wherein a support (14) is provided under said blade member, said support having an upper portion (16) to which said blade member is attached and an extension (20) extending downward therefrom, said upper portion having a plurality of waves (17) aligned with said plurality of waves (15) of said blade member, said housing having a slot (25) receiving said extension (20), said extension being slidably mounted within said slot. 16. A cartridge as claimed in claim 14, wherein said cartridge has a plurality of said blades with blade members, and in that said waves in one blade member are aligned with waves in another blade member. 17. A cartridge as claimed in claim 14, wherein said cartridge has a plurality of said blades and said blades are fixedly mounted in said housing. 18. A cartridge as claimed in claim 14, wherein said cartridge has a plurality of said blades and said blades are movably mounted in said housing, 19. A cartridge as claimed in claim 17, wherein said blades are separated by a spacer and mounted on a platform portion (44) of said housing. 20. A cartridge as claimed in claim 14, wherein said housing has connectingleti'ucture for connection to a handle and pivoting providing pivoting of said blades with respect to said handle. 21. A cartridge as claimed in claim 20, wherein said connecting means and said pivoting means by structure thai provide^ a pivotal connection between said cartridge and said handle. 22. A blade for a shaving razor substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings. 23. A razor blade cartridge substantially as hereinbefore described with reference to and as illustrated in the accompanying description.

Documents:

450-del-1998-abstract.pdf

450-del-1998-claims.pdf

450-del-1998-correspondence-others.pdf

450-del-1998-correspondence-po.pdf

450-del-1998-description (complete).pdf

450-del-1998-drawings.pdf

450-DEL-1998-Form-1.pdf

450-del-1998-form-13.pdf

450-del-1998-form-19.pdf

450-del-1998-form-2.pdf

450-del-1998-form-3.pdf

450-del-1998-form-4.pdf

450-del-1998-form-6.pdf

450-del-1998-gpa.pdf

450-del-1998-petition-137.pdf

450-del-1998-petition-138.pdf