Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B26—HAND CUTTING TOOLS; CUTTING; SEVERING
  • B26B—HAND-HELD CUTTING TOOLS NOT OTHERWISE PROVIDED FOR
  • B26B21/00—Razors of the open or knife type; Safety razors or other shaving implements of the planing type; Hair-trimming devices involving a razor-blade; Equipment therefor
  • B26B21/54—Razor-blades
  • B26B21/56—Razor-blades characterised by the shape
  • B26B21/565—Bent razor blades; Razor blades with bent carriers
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B26—HAND CUTTING TOOLS; CUTTING; SEVERING
  • B26B—HAND-HELD CUTTING TOOLS NOT OTHERWISE PROVIDED FOR
  • B26B21/00—Razors of the open or knife type; Safety razors or other shaving implements of the planing type; Hair-trimming devices involving a razor-blade; Equipment therefor
  • B26B21/54—Razor-blades
  • B26B21/56—Razor-blades characterised by the shape
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
  • B21D—WORKING OR PROCESSING OF SHEET METAL OR METAL TUBES, RODS OR PROFILES WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
  • B21D53/00—Making other particular articles
  • B21D53/60—Making other particular articles cutlery wares; garden tools or the like
  • B21D53/64—Making other particular articles cutlery wares; garden tools or the like knives; scissors; cutting blades
  • B21D53/645—Making other particular articles cutlery wares; garden tools or the like knives; scissors; cutting blades safety razor blades
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B24—GRINDING; POLISHING
  • B24B—MACHINES, DEVICES, OR PROCESSES FOR GRINDING OR POLISHING; DRESSING OR CONDITIONING OF ABRADING SURFACES; FEEDING OF GRINDING, POLISHING, OR LAPPING AGENTS
  • B24B3/00—Sharpening cutting edges, e.g. of tools; Accessories therefor, e.g. for holding the tools
  • B24B3/36—Sharpening cutting edges, e.g. of tools; Accessories therefor, e.g. for holding the tools of cutting blades
  • B24B3/48—Sharpening cutting edges, e.g. of tools; Accessories therefor, e.g. for holding the tools of cutting blades of razor blades or razors
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B26—HAND CUTTING TOOLS; CUTTING; SEVERING
  • B26B—HAND-HELD CUTTING TOOLS NOT OTHERWISE PROVIDED FOR
  • B26B21/00—Razors of the open or knife type; Safety razors or other shaving implements of the planing type; Hair-trimming devices involving a razor-blade; Equipment therefor
  • B26B21/54—Razor-blades

Definitions

• the invention relates to a razor blade, a cartridge including the razor blade, and a method of making the razor 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.
• 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.
• 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 a direction that is parallel to the thickness axis.
• the blade includes an "L-shaped" support under the blade member; the support is thicker than the blade member, and includes an upper portion to which the blade member is attached and an extension extending downward therefrom; the upper portion has 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 (most 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 member is made of metal between about 0.002" and about 0.010" thick, preferably between about 0.003" and about 0.004" thick.
• the waves have an amplitude of distance between the crests and valleys that is between 50% and 150% 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.
• 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 amplitude that causes a decrease in shaving comfort when compared to a linear front cutting edge.
• the waves Preferably have an amplitude between crests and valleys of greater than 0.001" and less than 0.012", most preferably between 0.002" and 0.004".
• 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.
• 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.
• Waves 15 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 and aligned with waves 15.
• the valleys of 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 cause undue discomfort or irritation and propensity to cause nicks and cuts during normal up and down shaving strokes.
• the amplitude also yields acceptable overall shaving comfort values as compared to flat blades based upon shave tests and accepted statistical analysis.
• Fig. 4 shows undeformed blade 10' including flat blade member 12' and support 14' prior to forming.
• Blade member 12' is preferably made of 0.003" or 0.004" thick razor blade quality stainless steel which is martensitic 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 stainless steel. Extension 20' of support 14' extends downward from upper platform 16 a distance of 0.0596".
• alternative razor blade cartridge 40 includes two fixed blades 42 on sandwiched platform support 44. Cartridge 40 also has guard member 46 and cap member 48. Blades 42 have waves of the same shape and amplitude as blade member 12, and the crests and valleys of the two blades are aligned.
• 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.
• the blade member 12' is preferably secured to support upper portion 16' by laser spot welding, as described in U.S. Patent No. 4,379,219, incorporated by reference herein.
• an undeformed blade 10' is formed in apparatus 49 between upper die 52 and lower die 50 to provide waves 15 and 17 (Fig. 3).
• Portion 16' of 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' elastically returns to approximately 50% of the maximum deflected value.
• a maximum die deflection of amplitude of about ⁇ 0.003 which corresponds to a crest to valley amplitude of about 0.006
• Opposed dies 50 and 52 have nonmatching surfaces so as to provide regions for material flow during forming of undeformed blade member 12' and undeformed upper support portion 16' into formed blade member 12 and formed upper support portion 16.
• upper die 52 is used with lower die 50 (Fig. 8) for three-point bending
• upper die 52 is used with lower die 50' (Fig. 9) for four-point bending.
• Three-point or four-point bending is used to permit material flow during the deflection and deformation process and to permit forming of upper portion 16' while extension 20' remains flat.
• upper die 52 has thirteen semi-circular ridges 56 with center-to-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. 8) has twelve circular ridges 60 with center-to-center spacing of 0.119", a depth "£" of 0.0358", a radius 74 of 0.0596", and a flat space "g" between ridges of 0.0096".
• Lower die 50' (Fig.
• the four points of contact for forming each wave are provided by two upper ridges 56 and the two lower ridges 62 between them.
• spot welds 18 are 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.
• the distance 78 between successive wave crests is set at 0.119", and the preferred crest to valley wave amplitude is about 0.003".
• Blades 10 (Fig. 5) and blades 42 (Fig. 6) are formed using similar dies. When the 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 when a blade is 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 blade 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 is substantially longer than with a flat blacle, thus providing more points of contact in stretching the skin.
• the waves also make the blade member a stiffer structure which is subject to less bending during shaving, tending to better maintain designed exposures and blade tangent angles during shaving than flat blade counterparts (i.e., made of the same thickness material).
• the increased strength provided to blade member 12 by the wavy structure can be estimated by assuming that the wave follows a sine curve and calculating and comparing moments of inertia (which determine the blade stiffness and resistance to deflection) for the wavy blades and the weaker undeformed flat blades.
• moments of inertia which determine the blade stiffness and resistance to deflection
• Fig. 10 the following formula can be used to describe the location of a midline through the blade member 12, Y n , as a function of length, x, and the upper surface Y n + h 2, and the lower surface, Y n - h/2:

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• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Life Sciences & Earth Sciences (AREA)
• Forests & Forestry (AREA)
• Dry Shavers And Clippers (AREA)
• Knives (AREA)
• Packaging Of Annular Or Rod-Shaped Articles, Wearing Apparel, Cassettes, Or The Like (AREA)
• Auxiliary Devices For Music (AREA)
• Pens And Brushes (AREA)

Applications Claiming Priority (3)

Publications (2)

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Country Status (18)

Cited By (1)

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• 1998
  • 1998-02-25 TW TW087102734A patent/TW378173B/zh not_active IP Right Cessation
  • 1998-02-26 WO PCT/US1998/003761 patent/WO1998038017A2/en not_active Ceased
  • 1998-02-26 ID IDW990867A patent/ID22706A/id unknown
  • 1998-02-26 AU AU63399/98A patent/AU6339998A/en not_active Abandoned
  • 1998-02-26 BR BR9807754-6A patent/BR9807754A/pt not_active IP Right Cessation
  • 1998-02-26 CN CNB988028808A patent/CN1163333C/zh not_active Expired - Fee Related
  • 1998-02-26 ZA ZA981629A patent/ZA981629B/xx unknown
  • 1998-02-26 JP JP53784698A patent/JP2001513681A/ja not_active Ceased
  • 1998-02-26 TR TR1999/02073T patent/TR199902073T2/xx unknown
  • 1998-02-26 ES ES98907644T patent/ES2174420T3/es not_active Expired - Lifetime
  • 1998-02-26 DE DE69805632T patent/DE69805632T2/de not_active Expired - Lifetime
  • 1998-02-26 AT AT98907644T patent/ATE218087T1/de not_active IP Right Cessation
  • 1998-02-26 KR KR1019997007745A patent/KR20000075679A/ko not_active Abandoned
  • 1998-02-26 EP EP98907644A patent/EP1011934B1/de not_active Expired - Lifetime
  • 1998-02-26 PL PL98335376A patent/PL186434B1/pl not_active IP Right Cessation
  • 1998-02-26 CA CA002278765A patent/CA2278765C/en not_active Expired - Lifetime
  • 1998-02-27 AR ARP980100887A patent/AR011895A1/es active IP Right Grant
  • 1998-02-27 CO CO98010857A patent/CO4761088A1/es unknown

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