Patent Application
20070234577
A preferred cutting member which may be formed by a method that includes a localized heat-treating process, and a razor containing the cutting member, will first be described with reference to
Referring to
As shown in
In certain embodiments, heat-treating device 310 is a laser device. The laser device can be used to locally harden a discrete region of strip 350 (e.g., the edge region of strip 350). For example, laser energy (e.g., laser light) from the laser device can be directed to the strip as the strip is conveyed from the roll to the sharpening device. Strip 350 can be conveyed at a rate of about 5 ft/min (1.5 m/min) to about 200 ft/min (61 m/min) (e.g., about 120 ft/min (36.6 m/min)). Generally, the power of the laser device is directly proportional to the rate at which strip 350 is conveyed. In some embodiments, the laser device is configured to produce energy at about 100 watts to about one kilowatt (e.g., about 200 watts). The light emitted from the laser device can have a wavelength of about 950 nm to about 1440 nm (e.g., about 1064 nm). The discrete region of the strip 350, which is contacted by the laser light, can reach a temperature of about 1050 degrees Celsius to about 1400 degrees Celsius (e.g., about 1200 degrees Celsius). The time for which the discrete region of strip 350 is heated depends on the power level of the laser device. Typically, the time for which the discrete region of strip 350 is heated decreases as the power level of the laser device increases, and vice versa. The laser energy can, for example, be applied to the discrete region of strip 350 for about 0.010 seconds to about 0.190 seconds. The hardness of the heated region of strip 350 can be increased as a result of the heat-treatment. The heated region of strip 350 can, for example, have a hardness of about 540 HV to about 750 HV (e.g., about 620 HV to about 750 HV).
While heat-treating device 310 has been described as a laser device, any of various other devices capable of locally treating discrete regions of strip 350 can be used. For example, the heat-treating device can include an induction coil that is arranged about a portion of strip 350 to heat, and thus harden, that portion of strip 350.
Moreover, the heat-treating device 310 may include multiple heat-treating devices, for example one or more heat-treating devices configured to heat the entire strip, and one or more heat-treating devices configured for localized heating. For instance, heat-treating device 310 may include a traditional furnace configured to heat the entire strip, followed by a laser configured for localized heating. In this case, the conventional furnace would impart hardness to the entire strip, and then the laser would generally be used to temper or soften a localized area of the strip, e.g., the bend area, to increase ductility.
Due to its relatively small area, the heated region of strip 350 generally self-quenches after being exposed to the laser energy. Alternatively or additionally, a cooling source (e.g., a cooling fluid) can be applied to the heated region of the strip to aid the quenching process.
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.
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.
Referring again to
Bending device 330 can be any device capable of forming a longitudinal bend in strip 350. In some embodiments, as shown in
To form bent region 360 of strip 350, the relatively planar strip 350 is positioned between punch 365 and die 370, as shown in
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).
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.
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.
The cutting member may have certain preferred characteristics, as will now be described.
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.
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).
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). In some embodiments, bent portion 115 has a hardness that is less than the hardness of base portion 110. 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. In certain embodiments, cutting member 100 has a substantially uniform hardness. In other 20 embodiments, cutting edge 120 is harder than the other portions of cutting member 100.
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. In some embodiments, bent portion 115 and the remainder of cutting member 100 have substantially the same ductility. In certain embodiments, bent portion 115 has greater ductility than the other portions of cutting member 100.
Cutting member 100 can be formed of any of various suitable materials, including GIN6 and GINB steels and other blade steels. 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.
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.
While certain embodiments have been described, other embodiments are possible.
For example, the localized heat-treating processes described above can be used to heat treat blades other than the bent blades described above. For instance, a localized heat-treating process can be used to locally harden the edge of a conventional blade such as the prior art razor blades described above with reference to
Moreover, 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.
As another example, while heat-treating device 310 has been described as being configured to treat an edge region of strip 350, heat treating device 310 can alternatively or additionally be arranged to treat additional regions of strip 350 (e.g., regions of strip 350 that are not intended to be sharpened by sharpening device 315). In some embodiments, for example the entire strip 350 is hardened by heat-treating device 310.
As a further example, while increasing the ductility of a region of strip 350 that is to be bent has been described above, additional or other regions of strip 350 (e.g., regions of strip 350 that are not intended to be bent by bending device 330) may be heat-treated to increase ductility. In certain embodiments, for example, substantially the entire strip 350 is heat-treated to increase its ductility. In some embodiments, as noted above, strip 350 is conveyed through a heat treating device to harden substantially the entire strip. After initially hardening substantially the entire strip an edge region of strip 350 is sharpened as described above. Then, strip 350 is subjected to heat treating to increase the ductility of substantially the entire strip, which can help to improve the bending of strip 350. Strip 350 can then be further processed as discussed above.
As another example, while the embodiments above describe heat-treating a discrete region of strip 350 to increase the ductility of that region, in certain embodiments, the cutting member forming process can be carried out without this heat-treating step. In such embodiments, strip 350 can be formed of a relatively ductile material. Strip 350 can be conveyed through heat-treating device 310 to locally harden an edge region of strip 350 so that the edge region can be sharpened. After being sharpened, strip 350 can be cut and bent without first heat-treating the bend region. The material from which strip 350 is formed, for example, can be sufficiently ductile so that the second heat-treating step is not required to prevent damage to the strip as a result of the bending process. After bending strip 350, the remainder of the process can be carried out in accordance with the description herein.
As an additional example, in some embodiments, a heating device is configured to apply heat to both longitudinal edges of strip 350. For example, one of the longitudinal edges can be heat-treated, as discussed above, in order to harden the region for sharpening, and the opposing longitudinal edge can be heat treated to reduce (e.g., to prevent) sweep within strip 350. For example, the opposing longitudinal edge can be heat-treated to substantially the same temperature as edge 352. In some embodiments, the regions that are heat-treated are symmetrical with respect to a center line of strip 350.
Other embodiments are within the scope of the claims.
