Classifications

• • C—CHEMISTRY; METALLURGY
  • C21—METALLURGY OF IRON
  • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
  • C21D9/00—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor
  • C21D9/18—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for knives, scythes, scissors, or like hand cutting tools
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
  • B05D—PROCESSES FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
  • B05D5/00—Processes for applying liquids or other fluent materials to surfaces to obtain special surface effects, finishes or structures
  • B05D5/08—Processes for applying liquids or other fluent materials to surfaces to obtain special surface effects, finishes or structures to obtain an anti-friction or anti-adhesive surface
  • B05D5/083—Processes for applying liquids or other fluent materials to surfaces to obtain special surface effects, finishes or structures to obtain an anti-friction or anti-adhesive surface involving the use of fluoropolymers
• • 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
• • 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
  • B26B21/58—Razor-blades characterised by the material

Definitions

• This invention relates to safety razor blades, either single edged or double edged, and more specifically to a method for processing steel strip to provide a razor blade structure capable of receiving a shave facilitating coating and that has improved shaving eflFectiveness and blade life, and to improved carbon steel razor blades manufactured in accordance with such method.
• the processing of steel strip stock into razor blades conventionally includes the steps of heating the strip stock in a hardening furnace, abruptly quenching the heated steel strip and then tempering the strip to increase its toughness by an age hardening process.
• One or both edges of the strip are then sharpened to the desired edge configuration.
• that configuration is a wedge shape, the included solid angle of which is about 25.
• the faces or sides of such cutting edges may extend back from the ultimate edge a distance of up to as much as 0.1 inch or even more.
• Each face need not be a single uninterrupted continuous surface or facet, but may consist of two or more facets formed by successive grinding or honing operations and intersecting each other along zones generally parallel to the ultimate edge.
• the final facet i.e. the facet immediately adjacent the ultimate edge, has a width as little as 7.5 microns or even less as compared to the diameter of beard hair which averages about 100 to 125 microns.
• a thin adherent coating which improves the shaving effectiveness of the razor blade and a prefferred form of this coating is a fluorocarbon polymer which functions not only to improve the eflectiveness of the first and succeeding shaves, but also to extend the shaving life of the blade.
• the application of such materials to the cutting edges involves heating the coated edge at an elevated temperature and carbon steel blades of conventional commercial configuration when subjected to such treatment have exhibited less improvement in shaving effectiveness than the maximum which might be expected to be obtained by the coating. For this reason the principal use of such coatings has been on stainless steel blades.
• Another object of the invention is to provide a method of increasing the included angle of the sharpened edge of a razor blade without modifying the sharpening equipment.
• Still another object of the invention is to provide an improved carbon steel razor blade.
• carbon steel strip Patented Mar. 17, 1970 stock of commercial razor blade quality is treated in a hardening and tempering sequence.
• the composition of this steel is a preferred form has a carbon content in the range of 1.151.30%; a silicon content in the range of 0.15-0.30%; a manganese content in the range 0.25- 0.50%; a chromium content in the range Oil-0.35%; with sulfur and phosphorus content each less than 0.045%.
• the balance of the steel is substantially iron with trace amounts of other elements.
• Such steel in strip form of a thickness of 0.0039 inch and a width of 0.880 inch is processed through a hardening, quenching and tempering sequence at a strip velocity of 65 feet per minute.
• a hardening furnace about fourteen feet in length is employed and the temperature in that furnace is maintained at at least 1'650 F. and preferably approximately 150 F. higher than normal (in the order of 1710" F.). That furnace temperature is controlled to significantly increase the amount of retained austenite in the tempered strip.
• the percent of retained austenite in the tempered strip should be at least 23% and preferably is at least 25% and in the range of 2528%.
• the steel strip After passing through the hardening furnace, the steel strip is quenched by passage through quench blocks which are cooled by water at a temperature of F. The strip is then further processed by passage through a tempering furnace three feet in length which is maintained at a temperature of 900 F.
• a coat of lacquer is then applied to the hardened strip and that coat of lacquer is cured in conventional manner.
• One or both of the edges of the strip are then sharpened with sharpening equipment using conventional sharpening techniques.
• sharpening equipment is adjusted to produce, on conventionally processed carbon steel blade strip, an included angle at the final facet (immediately adjacent the ultimate edge) of 25.
• the included angle actually produced in such steel is approximately 28", about 3 larger than that produced in conventional steel blades by this equipment.
• a fluorocarbon polymer coating is then applied to the cutting edges of the blade stock, preferably in accordance with the teaching in the copending patent application Ser. No. 384,805, filed July 23, 1964, in the name of Irwin W. Fischbein and assigned to the same assignee as this patent application.
• This processing involves heating the blade to a temperature preferably in the range of 590- 806 F. and provides on the cutting edge of the razor blade an adherent coating of solid fluorocarbon polymer.
• the heating conditions i.e. maximum temperature, length of time, etc.
• the polymer in the form of dispersion of finely divided particles in an inert volatile liquid, is applied by spraying in a 40 kv. electrostatic field to the sharpened cutting edges of the blade stock.
• the coated blades which dry almost immediately due to the evaporation of the inert liquid, are then heated to a temperature from 590-806 F. for 2 to 15 minutes, e.g. to 650 F. for ten minutes in an atmosphere of hydrogen gas, after which the hydrogen is displaced by nitrogen while cooling the blades to 350 F.
• the blades are finally cooled in air from 350 F. to room temperature.
• This last heating step is employed for the required curing of the coating, but it has a modifying effect on the metallurgy of of the underlying blade.
• an improved combination of retained austenite, included solid angle, and solid fluorocarbon coating is achieved.
• the increase in included solid angle would ordinarily be expected to result in a blade that has impaired shaving characteristics, but the present combination actually provides a blade that has improved shaving characteristics.
• Carbon steel razor blades processed in this manner have shaving characteristics that are significantly superior to the highest quality commercial carbon steel blades heretofore available and also have a shaving life that is greater than that of such high quality carbon steel blades heretofore commercially available.
• the method of increasing the included angle of a carbon steel razor blade in a sharpening process comprising the step of treating a strip of carbon steel by heating said strip in a hardening furnace maintained at a temperature in excess of 1650 F. for about fifteen seconds, promptly quenching said strip after hardening to a temperature of about 90 F. and then tempering said strip to produce a retained austenite content in excess of 23% in the steel blade stock to be sharpened.
• a process of manufacturing razor blades comprising the steps of treating a carbon steel strip by heating said strip in a hardening furnace maintained at a temperature in excess of 1650" F. and then promptly quenching and heat treating said strip after hardening to produce a retained austenite content in the steel in excess of 23%, sharpening an edge of the strip, depositing on the sharpened edge of the strip a composition comprising a solid fluorocarbon polymer, and heating said edge with the deposit thereon to form a coating adherent to the edge.
• a process according to claim 6 wherein said hardening step is performed by disposing said strip in a heating furnace maintained at said temperature in the order of 1710 F.

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• Engineering & Computer Science (AREA)
• Chemical & Material Sciences (AREA)
• Mechanical Engineering (AREA)
• Life Sciences & Earth Sciences (AREA)
• Forests & Forestry (AREA)
• Materials Engineering (AREA)
• Thermal Sciences (AREA)
• Crystallography & Structural Chemistry (AREA)
• Physics & Mathematics (AREA)
• Metallurgy (AREA)
• Organic Chemistry (AREA)
• Heat Treatment Of Articles (AREA)
• Coating Apparatus (AREA)
• Application Of Or Painting With Fluid Materials (AREA)
• Manufacturing Of Magnetic Record Carriers (AREA)

Applications Claiming Priority (1)

Publications (1)

Family

ID=24130964

Family Applications (1)

Country Status (15)

Cited By (11)

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Citations (7)

Family Cites Families (2)

• 0
  • DD DD63018D patent/DD63018A/xx unknown
• 1966
  • 1966-03-16 US US534651A patent/US3501334A/en not_active Expired - Lifetime
• 1967
  • 1967-03-14 GB GB02020/67A patent/GB1162757A/en not_active Expired
  • 1967-03-14 GR GR670132163A patent/GR32163B/el unknown
  • 1967-03-15 YU YU0505/67A patent/YU31529B/xx unknown
  • 1967-03-15 ES ES338054A patent/ES338054A1/es not_active Expired
  • 1967-03-15 DE DE1967G0049580 patent/DE1608423B1/de active Granted
  • 1967-03-15 FI FI670786A patent/FI45523C/fi active
  • 1967-03-16 AT AT254667A patent/AT292050B/de not_active IP Right Cessation
  • 1967-03-16 JP JP42016154A patent/JPS491373B1/ja active Pending
  • 1967-03-16 SU SU1139653A patent/SU347983A1/ru active
  • 1967-03-16 FR FR99023A patent/FR1519040A/fr not_active Expired
  • 1967-03-16 NL NL676703951A patent/NL148943B/xx unknown
  • 1967-03-16 SE SE03685/67A patent/SE332581B/xx unknown
  • 1967-07-31 BE BE702113D patent/BE702113A/xx unknown

Patent Citations (7)

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