Abstract:
A cutting member for a shaving razor includes an elongated blade portion that tapers to a cutting edge, an elongated base portion that is integral with the blade portion, and a bent portion, intermediate the blade portion and the base portion. In some implementations, at least part of the cutting member has a thickness of at least about 0.005 inch (0.127 millimeter).

Description:
TECHNICAL FIELD 
       [0001]    This invention relates to cutting members for shaving razors. 
       BACKGROUND 
       [0002]    Razor blades are typically formed of a suitable metallic sheet material such as stainless steel, which is slit to a desired width and heat-treated to harden the metal. The hardening operation utilizes a high temperature furnace, where the metal may be exposed to temperatures greater than 1145° C. for up to 18 seconds, followed by quenching. 
         [0003]    After hardening, a cutting edge is formed on the blade. The cutting edge typically has a wedge-shaped configuration with an ultimate tip having a radius less than about 1000 angstroms, e.g., about 200-300 angstroms. 
         [0004]    The razor blades are generally mounted on bent metal supports and attached to a shaving razor (e.g., a cartridge for a shaving razor).  FIG. 1 , for example, illustrates a prior art razor blade assembly that includes a planar blade  10  attached (e.g., welded) to a bent metal support  11 . Blade  10  includes a tapered region  14  that terminates in a cutting edge  15   16 . This type of assembly is secured to shaving razors (e.g., to cartridges for shaving razors) to enable users to cut hair (e.g., facial hair) with cutting edge  16 . Bent metal support  11  provides the relatively delicate blade  10  with sufficient support to withstand forces applied to blade  10  during the shaving process. Examples of razor cartridges having supported blades are shown in U.S. Pat. No. 4,378,634 and in U.S. patent application Ser. No. 10/798,525, filed Mar. 11, 2004, which are incorporated by reference herein. 
       SUMMARY 
       [0005]    In some aspects, the invention features a cutting member for a shaving razor, the cutting member including an elongated blade portion that tapers to a cutting edge; an elongated base portion that is integral with the blade portion; and a bent portion, intermediate the blade portion and the base portion. 
         [0006]    In one such aspect, at least part of the cutting member has a thickness of at least about 0.005 inch (0.127 millimeter). 
         [0007]    In another such aspect, the cutting member is formed of a material about 0.35 to about 0.43 percent carbon, about 0.90 to about 1.35 percent molybdenum, about 0.40 to about 0.90 percent manganese, about 13 to about 14 percent chromium, no more than about 0.030 percent phosphorus, about 0.20 to about 0.55 percent silicon, and no more than about 0.025 percent sulfur. 
         [0008]    In yet another of these aspects, at least part of the cutting member has a ductility of at least about seven percent elongation. 
         [0009]    Some embodiments include one or more of the following features. The cutting member may have an average thickness of about 0.005 inch (0.127 millimeter) to about 0.01 inch (0.254 millimeter); in some cases substantially the entire elongated blade, except for the cutting edge, has a thickness in this range. The bent portion may have an average thickness that is at least about  5  percent less than an average thickness of the base portion. The elongated base portion may be configured to be secured to the shaving razor. The elongated blade portion may extend at an angle of about 108 degrees to about 115 degrees relative to the elongated base portion. 
         [0010]    The invention also features a cutting member for a shaving razor, the cutting member including a first portion; a second portion; and a bent portion intermediate the first and second portions, the bent portion having a thickness that is at least about five percent less than an average thickness of the cutting member. 
         [0011]    The invention also features methods of making cutting members and razors including such members. 
         [0012]    In one aspect, the invention features a method including deforming a continuous strip of material, and then separating the continuous strip into multiple discrete blades, each blade having a first portion, a second portion, and a bent portion intermediate the first and second portions. 
         [0013]    Some embodiments may include one or more of the following features. Deforming the continuous strip of material may include pressing the strip of material between a punch and a die. Separating the continuous strip may include stamping or punching the strip. The method may also include punching longitudinally spaced apart slots in the strip prior to deforming the strip, the slots at least partially separating regions of the strip corresponding to the blades. 
         [0014]    In another aspect, the invention features a method including hardening a strip of blade steel; forming a cutting edge on the hardened strip; after forming the cutting edge, bending the strip along its length by coining the strip; and separating the bent strip into individual blades, each blade having a bent portion. 
         [0015]    Some embodiments may include one or more of the following features. The strip may be bent using a forming die that is configured so as not to touch the cutting edge. Bending the strip may reduce the thickness of the blade steel in the bent portion by at least about five percent relative to an original thickness of the blade steel. 
         [0016]    The invention also features razors and razor cartridges including the cutting members described herein. 
         [0017]    Embodiments can include one or more of the following advantages. 
         [0018]    In some embodiments, the cutting member can be affixed to a cartridge of the shaving razor without the use of bent supports. Consequently, the shaving razor can include fewer components and, therefore, can be more cost-efficient than many conventional shaving razors. 
         [0019]    In certain embodiments, the cutting member has a thickness that provides sufficient rigidity to prevent substantial deformation of the cutting member during use of the shaving razor. 
         [0020]    In some embodiments, the cutting member is formed of a blade steel that has a hardness sufficient for forming a cutting edge that can cut hair, and has a ductility that is sufficient to allow bending of the blade without fracture or other substantial defects. 
         [0021]    In some embodiments, the cutting members can be formed using a substantially continuous manufacturing process. 
         [0022]    Other features and advantages of the invention can be found in the description, the drawings, and the claims. 
     
     
       DESCRIPTION OF DRAWINGS 
         [0023]      FIG. 1  is a cross-sectional view of a prior art razor blade assembly including a planar cutting member attached to a bent support. 
           [0024]      FIG. 2A  is a cross-sectional view of an embodiment of a bent cutting member for a shaving razor. 
           [0025]      FIG. 2B  is a top view of the cutting member of  FIG. 2A . 
           [0026]      FIG. 2C  is a front view of the cutting member of  FIG. 2A . 
           [0027]      FIG. 3  illustrates a shaving razor that includes the bent cutting member of  FIG. 2A . 
           [0028]      FIG. 4  illustrates a method and apparatus for forming the cutting member of  FIG. 2A . 
           [0029]      FIG. 5  is a partial top view of a strip of blade steel after exiting a cutting device of the apparatus shown in  FIG. 4 . 
           [0030]      FIG. 6  is a partial top view of the strip of blade steel after exiting a bending device of the apparatus shown in  FIG. 4 . 
           [0031]      FIG. 7  is a cross-sectional view of the strip of blade steel taken along line  7 - 7  in  FIG. 4 . 
           [0032]      FIGS. 8A and 8B  illustrate an embodiment of a method of forming a bent region in the strip of blade steel. 
       
    
    
     DETAILED DESCRIPTION 
       [0033]    Referring to  FIG. 2A , a cutting member  100  includes a blade portion  105 , a base portion  110 , and a bent portion  115  that interconnects blade and base portions  105 ,  110 . Blade portion  105  terminates in a relatively sharp cutting edge  120 , while base portion  110  terminates in a relatively blunt end region. 
         [0034]    As shown in  FIG. 3 , cutting member  100  can be used in shaving razor  210 , which includes a handle  212  and a replaceable shaving cartridge  214 . Cartridge  214  includes housing  216 , which carries three cutting members  100 , a guard  220 , and a cap  222 . In other embodiments, the cartridge may include fewer or more blades. 
         [0035]    Cutting members  100  can be mounted within cartridge  214  without the use of additional supports (e.g., without the use of bent metal supports like the one shown in  FIG. 1 ). Cutting members  100  are captured at their ends and by a spring support under the blade portion  105 . The cutting members are allowed to move, during shaving, in a direction generally perpendicular to the length of blade portion  105 . As shown in  FIGS. 2A and 2B , the lower base portions  110  of cutting members  100  extend to the sides beyond the upper bent and blade portions  115 ,  105 . The lower base portions  110  can be arranged to slide up and down within slots in cartridge housing  216  while the upper portion rests against resilient arms during shaving. The slots of the cartridge housing  216  have back stop portions and front stop portions that define, between them, a region in which cutting members  100  can move forward and backward as they slide up and down in the slots during shaving. The front stop portions are generally positioned beyond the ends of blade portions  105 , so as not to interfere with movement of blade portions  105 . Cutting members  100  are arranged within cartridge  214  such that cutting edges  220  are exposed. Cartridge  214  also includes an interconnect member  224  on which housing  216  is pivotally mounted at two arms  228 . When cartridge  214  is attached to handle  212  (e.g., by connecting interconnect member  224  to handle  212 ), as shown in  FIG. 3 , a user can move the relatively flat face of cartridge  214  across his/her skin in a manner that permits cutting edges  120  of cutting members  100  to cut hairs extending from the user&#39;s skin. 
         [0036]    Referring again to  FIG. 2 , blade portion  105  of cutting member  100  has a length of about 0.032 inch (0.82 millimeters) to about 0.059 inch (1.49 millimeters). Base portion  110  has a length of about 0.087 inch (2.22 millimeters) to about 0.093 inch (2.36 millimeters). Bent portion  115  has a bend radius R of about 0.020 inch (0.45 millimeter) or less (e.g., about 0.012 inch (0.30 millimeter)). Relative to base portion  110 , blade portion  105  extends at an angle of about 115 degrees or less (e.g., about 108 degrees to about 115 degrees, about 110 to about 113 degrees). Cutting edge  120  of blade portion  105  has a wedge-shaped configuration with an ultimate tip having a radius less than about 1000 angstroms (e.g., from about 200 to about 300 angstroms). 
         [0037]    In certain embodiments, cutting member  100  is relatively thick, as compared to many conventional razor blades. Cutting member  100 , for example, can have an average thickness of at least about 0.003 inch (0.076 millimeter), e.g., about 0.005 inch (0.127 millimeter) to about 0.01 inch (0.254 millimeter). As a result of its relatively thick structure, cutting member  100  can provide increased rigidity, which can improve the comfort of the user and/or the cutting performance of cutting member  100  during use. In some embodiments, cutting member  100  has a substantially constant thickness. For example, blade portion  105  (except for cutting edge  120 ), base portion  110 , and bent portion  115  can have substantially the same thickness. 
         [0038]    In some embodiments, the thickness of bent portion  115  is less than the thickness of blade portion  105  and/or base portion  110 . For example, the thickness of bent portion  115  can be less than the thickness of blade portion  105  and/or base portion  110  by at least about five percent (e.g., about five percent to about 30 percent, about ten percent to about 20 percent). 
         [0039]    In certain embodiments, cutting member  100  (e.g., base portion  110  of cutting member  100 ) has a hardness of about 540 HV to about 750 HV (e.g., about 540 HV to about 620 HV). Bent portion  115  can, for example, have a hardness of about 540 HV to about 620 HV. The hardness of cutting member  100  can be measured by ASTM E92-82—Standard Test Method for Vickers Hardness of Metallic Materials. 
         [0040]    In some embodiments, cutting member  100  (e.g., bent portion  115  of cutting member  100 ) has a ductility of about seven percent to about 12 percent (e.g., about nine percent to about ten percent) elongation measured in uniaxial tension at fracture. The ductility of bent portion  115  can be measured, for example, by ASTM E345-93—Standard Test Methods of Tension Testing of Metallic Foil. 
         [0041]    In some embodiments, bent portion  115  and the remainder of cutting member  100  have substantially the same ductility. 
         [0042]    Cutting member  100  can be formed of any of various suitable materials. In certain embodiments, cutting member  100  is formed of a material having a composition comprised of about 0.35 to about 0.43 percent carbon, about 0.90 to about 1.35 percent molybdenum, about 0.40 to about 0.90 percent manganese, about 13 to about 14 percent chromium, no more than about 0.030 percent phosphorus, about 0.20 to about 0.55 percent silicon, and no more than about 0.025 percent sulfur. Cutting member  100  can, for example, be formed of a stainless steel having a carbon content of about 0.4 percent by weight, a chromium content of about 13 percent by weight, a molybdenum content of about 1.25 percent by weight, and amounts of manganese, chromium, phosphorus, silicon and sulfur within the above ranges.. 
         [0043]    In some embodiments, blade portion  105  and/or base portion  110  have minimal levels of bow and sweep. Bow is a term used to describe an arching normal to the plane in which the portion of the cutting member is intended to lie. Sweep, also commonly referred to as camber, is a term used to describe an arching within the plane in which the portion of the cutting member lies (e.g., an arching of the longitudinal edges of the portion of the cutting member). In some embodiments, blade portion  105  has a bow of about +0.0004 to about −0.002 inch (+0.01 to −0.05 millimeter) or less across the length of the blade portion. In certain embodiments, blade portion  105  has a sweep of about ±0.0027 inch (±0.07 millimeter) or less across the length of the blade portion. Base portion  110  can have a bow of about ±0.0024 inch (±0.060 millimeter) or less across the length of the base portion. By reducing the levels of bow and/or sweep in blade portion  105  and/or base portion  110 , the comfort of the user and/or the cutting performance of cutting member  100  can be improved. 
         [0044]      FIG. 4  shows a method and apparatus  300  for forming cutting members  100 . A continuous strip of blade steel  350  is conveyed (e.g., pulled by a rotating roll from a roll  305  of blade steel to a heat-treating device  310 , where strip  350  is heat-treated to increase the hardness of the blade steel. Strip  350  is then re-coiled into a roll  305  of hardened blade steel, and subsequently unwound and conveyed to a sharpening device  315 , where the hardened edge region of the strip is sharpened to form a cutting edge  352 . Strip  350  is again re-coiled into a roll  305  of hardened and sharpened blade steel, after which it is coated with hard and lubricious coatings using a coating device  325 . Strip  350  is then unwound and conveyed to a cutting/stamping station which includes a cutting device  320 . Cutting device  320  creates transverse slots  355  and adjoining slits  357  ( FIG. 5 ) across longitudinally spaced apart regions of strip  350  (as shown in  FIG. 5 ). Strip  350  is then conveyed to a bending device  330 , within the cutting/stamping station, that creates a longitudinal bend  360  in the regions of strip  350  between transverse slots  355  (shown in  FIGS. 6 and 7 ). After being bent, strip  350  is separated into multiple, discrete cutting members  100  by a separating device  335 , also within the cutting/stamping station. Cutting members  100  may then be arranged in a stack  340  for transport and/or for further processing, or assembled directly into cartridges, and a scrap region  365  of strip  350  is assembled onto roll  345  for recycling or disposal. Scrap region  365 , for example, can be used merely to help convey strip  350  through the blade forming devices described above. Alternatively or additionally, any of various other techniques can be used to convey strip  350  through the blade forming devices. 
         [0045]    Sharpening device  315  can be any device capable of sharpening the edge of strip  350 . Examples of razor blade cutting edge structures and processes of manufacture are described in U.S. Pat. Nos. 5,295,305; 5,232,568; 4,933,058; 5,032,243; 5,497,550; 5,940,975; 5,669,144; EP 0591334; and PCT 92/03330, which are hereby incorporated by reference. 
         [0046]    Cutting device  320  can be any of various devices capable of providing slots  355  and/or slits  357  in strip  350 . In some embodiments, cutting device is a punch press. In such embodiments, the progression of strip  350  can be periodically paused in order to allow the punch press to stamp slots  355  and/or slits  357  in strip  350 . Cutting device  320  can alternatively or additionally be any of various other devices, such as a high power laser or a scoring operation followed by a bending or fracturing operation. 
         [0047]    Referring again to  FIG. 5 , after strip  350  has been conveyed through cutting device  320 , strip  350  includes multiple, longitudinally spaced apart slots  355  and that extend inwardly from the sharpened edge of the strip to a central region of the strip. Slits  357  extend inwardly from slots  355 . Slots  355  are spaced apart by a distance that corresponds to the width of cutting members  100 . In some embodiments, adjacent slots  355  are spaced apart from one another by about 36.20 millimeters to about 36.50 millimeters. In certain embodiments, adjacent slits are spaced apart from one another by about 37.26 millimeters to about 37.36 millimeters. By providing discrete regions that are separated by slots  355 , the bending of strip  350  can be improved. 
         [0048]    Bending device  330  can be any device capable of forming a longitudinal bend in strip  350 . In some embodiments, as shown in  FIGS. 8A and 8B , bending device  330  is an assembly that includes a punch  365  and a die  370 . Punch  365  includes a curved portion  367  that is configured to mate with an associated curved portion  372  of die  370 . Generally, curved portion  367  of punch  365  has a radius that is slightly larger than a radius of curved portion  372  of die  370 . Curved portion  367  of punch  365 , for example can have a radius of about 0.0231″ to about 0.0241″, while curved portion  372  of die  370  can have a radius of about 0.010″ to about 0.014″. Punch  365  also includes a protrusion  369  that is configured to contact a portion of strip  350  that, as discussed below, is offset from sharpened edge  352  of strip  350 . 
         [0049]    To form bent region  360  of strip  350 , the relatively planar strip  350  is positioned between punch  365  and die  370 , as shown in  FIG. 8A . Punch  365  and die  370  are then moved toward one another such that curved portions  367  and  372  generally mate. Punch  365  can, for example, be moved toward die  370  at a rate of about 25 ft/min (10 m/min) to about 500 ft/min (200 m/min). As punch  365  and die  370  are moved toward one another, protrusion  369  of punch  365  contacts a region of strip  350  offset from sharpened edge  352 . As punch  365  and die  370  mate with one another, strip  350  is deformed into a bent position between punch  365  and die  370 . Due to the configuration of punch  365  and die  367 , sharpened edge  352  can remain untouched throughout the bending process. This to arrangement can help to prevent damage to the relatively delicate, sharpened edge  352  of strip  350 . 
         [0050]    As a result of the bending process, the thickness of strip  350  in bent region  360  can be reduced, relative to the thickness of strip  350  prior to being bent, by at least about five percent (e.g., about five percent to about 30 percent). Strip  350  in bent region  360 , for example, can have a thickness of about 0.0035 inch (0.089 millimeter) to about 0.0095 inch (0.241 millimeter), while the remainder of strip  350  can have a thickness of about 0.005 inch (0.127 millimeter) to about 0.01 inch (0.254 millimeter). 
         [0051]    Separating device  335  can be any device capable of separating the regions of strip  350  between slots  355  from the remainder of strip  350  to form discrete cutting members  100 . In some embodiments, separating device  335  is a punch press. The progression of strip  350  can be periodically paused to allow the punch press to accurately separate the regions of strip  350  between slots  355  from the remainder of strip  350  to form cutting members  100 . 
         [0052]    Other devices capable of separating the regions of strip  350  between slots  355  from the remainder of strip  350  can alternatively or additionally be used. Examples of such devices include a high power laser or a scoring operation followed by a bending or fracturing operation. 
         [0053]    While certain embodiments have been described, other embodiments are possible. 
         [0054]    As an example, the order of many of the process steps discussed above can be altered. The process steps can be ordered in any of various different combinations. 
         [0055]    Other embodiments are within the scope of the claims.