EP0126128B1 - Rasierklingen - Google Patents

Rasierklingen Download PDF

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Publication number
EP0126128B1
EP0126128B1 EP19830903805 EP83903805A EP0126128B1 EP 0126128 B1 EP0126128 B1 EP 0126128B1 EP 19830903805 EP19830903805 EP 19830903805 EP 83903805 A EP83903805 A EP 83903805A EP 0126128 B1 EP0126128 B1 EP 0126128B1
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EP
European Patent Office
Prior art keywords
tip
edge
blade
stainless steel
equation
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired
Application number
EP19830903805
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English (en)
French (fr)
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EP0126128A1 (de
Inventor
Francis Russell Curry
Edwin Lloyd Glasson
Joan Pumfrey
Romuald Kozlowski
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Gillette Co LLC
Original Assignee
Gillette Co LLC
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Publication date
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Application filed by Gillette Co LLC filed Critical Gillette Co LLC
Publication of EP0126128A1 publication Critical patent/EP0126128A1/de
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    • 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
    • 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 razor blades and is particularly concerned with the shaping of the cutting edge.
  • the invention resides in a razor blade having a cutting edge tip of-stainless steel, the cross-sectional shape of which up to a distance of 40 ⁇ m from the extreme edge is substantially described by the equation: in which w is the thickness in ⁇ m of the tip at a distance d in ⁇ m from the extreme edge of the blade; wherein a and n are constants, a is defined as a factor of proportionality not greater than 0.8 and n is defined as an exponent having a value in the range 0.65 to 0.75.
  • the included angle between the tip facets in the region from 40 pm to 100 11m from the extreme edge is within the range 7°-14° and preferably 9° to 112°.
  • blades having these tip characteristics provide improved shaving on comparative shave testing, but are sufficiently strong to give a reasonable useful life.
  • Cutting edges on razor blades are sharpened by grinding a succession of pairs of facets (usually three) of different included angles onto a strip of steel by means of suitably arranged abrasive wheels.
  • the cross-section through such an edge is illustrated in Figure 1 with typical values for dimensions and angles shown, and is customarily described as a "3-facet edge".
  • strip deflection in the sharpening machine together with the mechanical interaction between the steel and the abrasive particles of the wheel, produces final facets which are usually not planar but slightly convex.
  • the curvature is a function of the type of steel and abrasive wheel used, as well as the sharpening machine setting parameters.
  • the blade tip cross section in this region is customarily referred to as "Gothic arched".
  • the curvature prohibits precise geometrical definition of this part of the blade tip by means of a single parameter so that. it is usual to characterise the shape by defining tip thicknesses (or “chord widths") at various distances back from the edge.
  • An alternative method is to ascribe a mathematical equation to fit the form of each half of the facet cross-section. These methods are illustrated in Figure 2.
  • a razor blade is held in the razor at an angle of approximately 25°, and with the edge in contact with the skin, it is moved over the face so that when the edge encounters a beard hair, it enters and severs it by progressive penetration, aided by a wedging action. It is believed that the cut portion of the hair (which is on average about 100 ⁇ m diameter) remains pressed in contact with the blade facets remote from the facial skin surface for a penetration up to only about half the hair diameter. Beyond this, the hair can bend and contract away from the blade to relieve the wedging forces. The resistance to penetration through reaction between hair and blade facets therefore occurs only over about the first 50 pm of the blade tip back from the edge and the geometry of the blade tip in this region is regarded as being the most important from the cutting point of view. This is illustrated in Figure 3.
  • Blades currently produced have tip geometries with some dimensions which are below these minimum values and are known to become dulled by edge bending during the normal shaving life (which is on average, approximately 10 days for a blade made from conventional razor blade stainless steel).
  • the blade tip cross-section is first narrowed by grinding the three facets to smaller included angles than those typified in Figure 1. This produces a blade tip whose cross-section is generally narrower throughout and, importantly, in the 0-40 pm distance back from the edge, which is of particular interest during hair cutting. Such an edge is too weak to withstand stresses during shaving and must be further modified. This is achieved by adding what amounts to a fourth sharpening stage. It is carried out using rotating interlocking discs or spirals of leather or synthetic leather, (usually called "strops”) with abrasive material added to their peripheries.
  • strops rotating interlocking discs or spirals of leather or synthetic leather
  • abrasive stropping Because of the flexibility of the strop leather, allowing it to conform somewhat to the sharpened blade tip, abrasive stropping increases the curvature of the final facet, close to the edge, while having less effect on the facet shape further back.
  • the ultimate tip radius of the edge should be conventional, with an average value of less than 1000°A and preferably less than 500°A as stated, for example, in British Patent Specification 1,378,550 (U.S. 3,761,374), that is, within the normal range for conventionally sharpened edges.
  • Blades in accordance with the invention have been found to have superior shaving performance when compared with conventional blades on a standard shaving test.
  • Stainless steel razor blade strip of nominal composition 13% Cr, 0.6% C, was hardened and tempered in accordance with conventional practice, and sharpened by grinding and honing to produce edges of three facet configuration, as illustrated in Figure 1, but with included angles smaller than those conventionally manufactured.
  • the blades were passed between rotating strops of artificial leather, whose surfaces contained fine alumina abrasive, in the manner of conventional abrasive stropping, where the angle set on the strops (which is the included angle between the tangents to the strops at their point of intersection, as shown in Figure 9) was in the range 30°-34°.
  • the facets were provided with a metallic coating of an alloy of chromium and platinum (applied in accordance with U.S. Patent 3,829,969) with a superimposed coating of fluorocarbon material, (such as described in British Patent 906,005).
  • the blade tip cross-sections were measured using optical interferometry.
  • a blade is placed under the objective lens of a metallurgical microscope fitted with Michelson type interferometer and viewed at a magnification of about 1000x.
  • the interferometer is adjusted to produce fringes which are oriented at right angles to the edge of the blade.
  • the blade is tilted at an -appropriate angle so that the fringes are displaced to reveal the topography of the blade facets.
  • the fringe spacing is adjusted so that fringe displacements can be readily measured at various distances back from the edge. Knowing the angle of tilt, the tip shape is calculated from the sum of these fringe displacements, measured at corresponding positions on each side of the blade.
  • chord widths w at distances d from the extreme edge were as set out below:
  • the smaller gradient is a primary characteristic of the present embodiment and results in the fact that the blade tip of the present embodiment, compared with those of the prior art, is relatively thick and strongly arched close to the extreme edge, but relatively thin over the remainder of the tip.
  • the included facet angles in the region 40-100 11m from the tip are in the range 9° to 11 3 ° but making due allowance for manufacturing tolerances could be in the range 7° to 12° or even 7° to 14°.
  • tip shapes described above are for stainless steel blades and could be made substantially thinner for harder blade materials such as sapphire, titanium carbide or diamond.
  • chord widths In inverse proportion to the square root of the yield strength of the harder material in comparison with stainless steel, we reduce the corresponding chord widths in inverse proportion to the square root of the yield strength of the harder material in comparison with stainless steel. In the case of diamond, for example, the chord widths would be approximately 40% of those calculated for stainless steel.
  • the tip region of a stainless steel blade may be coated with a material harder than stainless steel and having a higher yield strength.
  • the chord widths given by the basic equation are reduced by adopting the modified formula: in which m is the ratio of the yield strength of the coating material to that of stainless steel.
  • the value for w must also satisfy the equation where h is the thickness of the coating.
  • the blade tips may, in each case, be coated with materials such as p.t.f.e, which further enhance the cutting action.
  • the thicknesses of such coatings are, of course ignored for the purposes of calculating the tip chord widths.

Landscapes

  • Life Sciences & Earth Sciences (AREA)
  • Forests & Forestry (AREA)
  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Dry Shavers And Clippers (AREA)
  • Knives (AREA)
  • Polishing Bodies And Polishing Tools (AREA)

Claims (4)

1. Rasierklinge mit einem Schneidkantenende aus Edelstahl, deren Querschnittsgestalt bis zu einer Entfernung von 40 um von der außersten Kante im wesentlichen durch die Gleichung:
Figure imgb0007
beschrieben wird, wobei w die Dicke in um des Endes in einer Entfernung d in µm vom äußersten Rand der Klinge ist, wobei a und n Konstanten sind, a als ein Proportionalitätsfaktor von nicht größer als 0,8 definiert ist und n als ein Exponent eines Wertes im Bereich zwischen 0,65 und 0,75 definiert ist.
2. Rasierklinge nach Anspruch 1, dadurch modifiziert, daß wenigstens das Schneidende der Klinge aus einem Material besteht, das eine höhere Streckfestigkeit als Edelstahl hat, wobei die Dicke w, die man aus der genannten Gleichung erhält, umgekehrt proportional zu Quadratwurzel des Verhältnisses der Streckfestigkeit des härten Materials zu derjenigen von Edelstahl vermindert ist.
3. Rasierklinge nach Anspruch 1, dadurch modifiziert, daß das Schneidkantenende mit einem Material beschichtet ist, das eine größere Streckfestigkeit als rostfreier Stahl aufweist, wobei die Querschnittsgestalt des Schneidkantenendes durch die Gleichung
Figure imgb0008
definiert ist, wobei m das Verhältnis der Streckfestigkeit der Hartbeschichtung zu der von Edelstahl ist und a ebenfalls die Gleichung:
Figure imgb0009
befriedigt, wobei h die Dicke in um der Beschichtung ist.
4. Rasierklinge nach Anspruch 1, bei der die Klingenkante mit Waten in einer Entfernung zwischen 10 und 100 µm von der äußersten Kante versehen ist, welche Waten gegen die Kante mit einem eingeschlossenen Winkel im Bereich von 7° bis 12° und vorzugsweise von 9° bis 11,5° konvergieren.
EP19830903805 1982-11-19 1983-11-14 Rasierklingen Expired EP0126128B1 (de)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GB8233014 1982-11-19
GB8233014 1982-11-19

Publications (2)

Publication Number Publication Date
EP0126128A1 EP0126128A1 (de) 1984-11-28
EP0126128B1 true EP0126128B1 (de) 1987-06-24

Family

ID=10534368

Family Applications (1)

Application Number Title Priority Date Filing Date
EP19830903805 Expired EP0126128B1 (de) 1982-11-19 1983-11-14 Rasierklingen

Country Status (9)

Country Link
EP (1) EP0126128B1 (de)
JP (1) JPS59502135A (de)
CA (1) CA1229476A (de)
DE (1) DE3372189D1 (de)
ES (1) ES275817Y (de)
GB (1) GB2130955B (de)
IN (1) IN160884B (de)
MX (1) MX161634A (de)
WO (1) WO1984002104A1 (de)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP3037226A1 (de) * 2014-12-22 2016-06-29 BIC-Violex S.A. Rasierklinge

Families Citing this family (15)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CA2234966A1 (en) * 1997-06-10 1998-12-10 Brian G. Balistee Improved blade edge
KR100914866B1 (ko) * 2001-07-11 2009-08-31 코닌클리케 필립스 일렉트로닉스 엔.브이. 절삭 부재, 면도 헤드, 및 면도 도구
US7144403B2 (en) 2003-07-29 2006-12-05 Alcon, Inc. Surgical knife
JP4575735B2 (ja) * 2004-09-27 2010-11-04 フェザー安全剃刀株式会社 ミクロトーム替刃
US9751230B2 (en) * 2014-05-19 2017-09-05 The Gillette Company Razor blades
WO2016015771A1 (en) 2014-07-31 2016-02-04 Bic-Violex Sa Razor blade coating
US11230025B2 (en) 2015-11-13 2022-01-25 The Gillette Company Llc Razor blade
US11654588B2 (en) 2016-08-15 2023-05-23 The Gillette Company Llc Razor blades
EP3372362A1 (de) * 2017-03-08 2018-09-12 BIC-Violex S.A. Rasierklinge
EP3372361A1 (de) 2017-03-08 2018-09-12 BIC-Violex S.A. Rasierklinge
JP6864034B2 (ja) * 2019-05-13 2021-04-21 ビック・バイオレクス・エス・エー 剃刀の刃
KR20210039205A (ko) * 2019-10-01 2021-04-09 주식회사 도루코 면도날
US20210276211A1 (en) * 2020-03-05 2021-09-09 John Robert Harris Razor blade with improved asymmetric profile
EP3895857A1 (de) * 2020-04-16 2021-10-20 GFD Gesellschaft für Diamantprodukte mbH Rasiervorrichtung
KR102516887B1 (ko) * 2020-06-16 2023-03-31 주식회사 도루코 면도날

Family Cites Families (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3461616A (en) * 1966-10-14 1969-08-19 Gillette Co Methods and apparatus for sharpening razor blades or similar cutting tools
GB1258348A (de) * 1969-10-15 1971-12-30
GB1350594A (en) * 1970-02-05 1974-04-18 Gillette Industries Ltd Sharpening cutting edges
US3761373A (en) * 1971-07-09 1973-09-25 Gillette Co Process for producing an improved cutting tool
GB1465697A (en) * 1973-06-20 1977-02-23 Wilkinson Sword Ltd Razor blades

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP3037226A1 (de) * 2014-12-22 2016-06-29 BIC-Violex S.A. Rasierklinge
EP3037226B1 (de) 2014-12-22 2017-07-19 BIC-Violex S.A. Rasierklinge
US11230024B2 (en) 2014-12-22 2022-01-25 Bic-Violex Sa Razor blade

Also Published As

Publication number Publication date
GB2130955B (en) 1985-10-02
EP0126128A1 (de) 1984-11-28
WO1984002104A1 (en) 1984-06-07
GB8330432D0 (en) 1983-12-21
CA1229476A (en) 1987-11-24
IN160884B (de) 1987-08-15
ES275817Y (es) 1984-12-16
GB2130955A (en) 1984-06-13
MX161634A (es) 1990-11-27
JPH0532076B2 (de) 1993-05-14
JPS59502135A (ja) 1984-12-27
DE3372189D1 (en) 1987-07-30
ES275817U (es) 1984-05-16

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