Razor Blade and Method of Manufacture

Abstract

A method for making a razor blade having a bent portion is disclosed. The method includes: providing an elongated strip of stainless steel that can be 0.076 mm thick; hardening the strip; providing a cutting edge along an edge of the strip and providing coating(s) on the cutting edge. The stainless steel has a carbon content preferably between 0.45% and 0.55% by weight. The strip is separated lengthwise into discrete razor blades. The bent portion of the razor blade is then formed using a swivel bending process. When the razor blade is bent to define an included angle of 90 degrees between planar regions adjacent the bent portion and an inner surface having a radius about 0.3-0.35 mm, the outer surface of the bent portion is free from macro-cracks.

1 . A method of making a razor blade having a bent portion, comprising the steps of:
 a) providing an elongated strip of stainless steel having a front edge portion and a back edge portion, the stainless steel having a carbon content less than 0.60% by weight;   b) hardening the strip to a first hardness;   c) providing a cutting edge extending along the front edge portion of the elongated strip;   d) cutting a lengthwise extending portion from the strip, the lengthwise extending portion providing a discrete razor blade having a length suitable for use in a razor cartridge housing, each discrete razor blade including a cutting edge, a back edge portion and a body portion therebetween; and   e) forming a region of the body portion by swivel bending to provide a bent portion in the body portion;   wherein the razor blade thus formed includes a first generally planar portion between the cutting edge and the bent portion and a second generally planar portion between the bent portion and the back edge portion.   
   
   
       2 . The method of  claim 1 , wherein the process further includes a step of perforating one or more apertures. 
   
   
       3 . The method of  claim 2 , wherein the step of perforation occurs before step e) and after step d). 
   
   
       4 . The method of  claim 1 , wherein the carbon content is between 0.45% and 0.55% carbon by weight. 
   
   
       5 . The method of  claim 1 , wherein the stainless steel further includes between 1.0 and 1.6% molybdenum by weight. 
   
   
       6 . The method of  claim 1 , wherein the first hardness is in the range 660 HV to 850 HV. 
   
   
       7 . The method of  claim 1 , wherein the method further includes the step of annealing at least a portion of the strip containing the cutting edge to reduce the hardness of the portion of the strip containing the cutting edge to a second hardness of at least 600 HV. 
   
   
       8 . The method of  claim 1 , wherein step d) occurs during a curing process for a PTFE coating applied to the cutting edge. 
   
   
       9 . The method of  claim 1 , wherein, when the razor blade is formed such that the first planar portion is generally perpendicular to the second planar portion, an outer surface of the bent portion is free from macro-cracks having a depth more than ⅔ the thickness of the strip. 
   
   
       10 . A razor blade having a bent portion, comprising:
 a cutting edge portion and a back edge portion;   a bent portion between the cutting edge portion and the back edge portion, the bent portion having an inner surface and an outer surface and being provided by a swivel bending process;   a first generally planar portion between the cutting edge portion and the bent portion; and   a second generally planar portion between the bent portion and the back edge portion, each planar portion having a thickness;   wherein the first generally planar portion and the second generally planar portion define an include angle less than 118 degrees therebetween;   wherein the razor blade comprises less 0.60% carbon;   wherein the inner surface of the bent portion includes a radius less than 0.5 mm; and   wherein the outer surface of the bent portion is free from macro-cracks having a depth more than ⅔ the thickness.   
   
   
       11 . The razor blade of  claim 10 , wherein the inner surface of the bent portion is parti-cylindrical and defines a radius about 0.3 mm. 
   
   
       12 . The razor blade of  claim 10 , wherein the first generally planar portion is generally perpendicular to the second generally planar portion. 
   
   
       13 . A razor cartridge, comprising:
 a housing having a guard at the front, a cap at the rear and a blade mounting region between the guard and the cap;   a plurality of razor blades, each having a bent portion, disposed in the blade mounting region, wherein each razor blade comprises:   a cutting edge portion and a back edge portion;   a bent portion between the cutting edge portion and the back edge portion, the bent portion having an inner surface and an outer surface and being provided by a swivel bending process;   a first generally planar portion between the cutting edge portion and the bent portion; and   a second generally planar portion between the bent portion and the back edge portion, each planar portion having a thickness;   wherein the first generally planar portion and the second generally planar portion define an include angle less than 118 degrees therebetween;   wherein the razor blade comprises less than 0.60% carbon;   wherein the inner surface of the bent portion includes a radius less than 1.0 mm; and   wherein the outer surface of the bent portion is free from macro-cracks having a depth greater than ⅔ the thickness.   
   
   
       14 . Apparatus to provide a bent portion in a razor blade, comprising:
 a first jaw;   a second jaw including a parti-cylindrical surface having an axis, and a relief face, wherein the first jaw and the second jaw are adapted to clamp a portion of a razor blade adjacent one of a cutting edge portion and an opposed edge portion; wherein the other of the cutting edge portion and the opposed edge portion extend therefrom and wherein one of the first jaw and the second jaw further comprises a reference surface adapted to abut one of the cutting edge portion and the opposed edge portion; and   a nose adapted to rotate about the axis of the second jaw through a predetermined angle of rotation, the nose having an arcuate surface adapted to contact a surface of the razor blade with a predetermined contact pressure;   wherein, when a razor blade is clamped between the first jaw and the second jaw and the nose is subsequently rotated through the predetermined angle of rotation the razor blade is provided with a bent portion.   
   
   
       15 . The apparatus of  claim 14 , wherein the nose is adapted to rotate about a nose axis and wherein the arcuate surface of the nose is adapted to roll on the surface of the razor blade without sliding relative to the surface of the razor blade.