U.S. patent number 3,750,285 [Application Number 05/052,527] was granted by the patent office on 1973-08-07 for guarded razor edge apparatus.
Invention is credited to Gunnar P. Michelson.
United States Patent |
3,750,285 |
Michelson |
August 7, 1973 |
GUARDED RAZOR EDGE APPARATUS
Abstract
A razor blade has a guarded cutting edge comprising a
multiplicity of relatively short and thin guard members bent into
relatively V-shaped form and permanently secured in substantially
equidistantly spaced relation to the blade edge. A method for
applying the guard members to the blade edge uses guard members
having a hardness which is less than that of the blade edge. The
guard members are bent over the blade edge using the relatively
greater hardness of the blade edge to slightly deform the guard
members and thereby clamp them to the blade edge.
Inventors: |
Michelson; Gunnar P. (Santa
Barbara, CA) |
Family
ID: |
21978197 |
Appl.
No.: |
05/052,527 |
Filed: |
July 6, 1970 |
Current U.S.
Class: |
30/346.58;
30/78 |
Current CPC
Class: |
B26B
21/4006 (20130101) |
Current International
Class: |
B26B
21/40 (20060101); B26B 21/00 (20060101); B26b
021/54 () |
Field of
Search: |
;30/51,78,346.5,346.58,76,77 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Riordon; Robert C.
Assistant Examiner: Peters; J. C.
Claims
I claim:
1. In a safety razor blade having a flat base structure, and an
elongated cutting edge integral with a side of the razor blade base
structure, a guarded cutting edge comprising
a multiplicity of separate elongated metal thread-like guard
members bent into substantially V-shaped form wherein each guard
member defines a pair of relatively short ends converging at a
rounded corner section, the guard members being fitted over the
blade cutting edge and spaced substantially equidistantly apart
along the blade cutting edge with their rounded corner sections
protruding forward of the blade cutting edge, and
means for independently providing rigid and permanent attachment of
the respective ends of each guard member to the razor blade base
structure at points relatively close to the blade cutting edge to
support the guard members in a substantially fixed relation
relative to the blade cutting edge.
2. A guarded cutting edge according to claim 1 wherein the ends of
the guard members are secured to the blade by spaced apart spot
welds on each side of the blade edge.
3. A guarded cutting edge according to claim 1 wherein the edge of
the razor blade base structure defines a pair of flanks converging
outwardly to a point, and wherein the respective ends of each guard
member are permanently secured to the respective flanks of the
blade base structure.
4. A guarded cutting edge according to claim 1 wherein the guard
members adjacent to the end portions of the razor blade base
structure are spaced closer together than the remaining guard
members.
5. A guarded cutting edge according to claim 1 wherein the guard
members are provided with a low-friction coating.
6. A guarded cutting edge according to claim 1 including means for
securing the respective corner sections of the guarded members to
the blade edge, the securing means comprising a tight pressed fit
formed between the inner contour of the corner section of each
guard member.
7. A guarded cutting edge according to claim 6 wherein the pressed
fit is formed by a notch formed at the inner contour of the corner
section of each guard member for cooperation with the blade
edge.
8. A guarded cutting edge according to claim 1 including means for
securing the respective corner sections of the guard members to the
blade edge, the securing means comprising a multiplicity of spaced
apart notches in the blade edge for cooperation with the inner
contour of the corner sections of the respective guard members.
9. A guarded cutting edge according to claim 1 wherein the width of
the guard members is between about 0.0015 to 0.0050 inch.
10. A guarded cutting edge according to claim 1 wherein the spacing
between substantially all guard members is between about 0.02 to
0.06 inch.
11. A guarded cutting edge according to claim 1 wherein the
cross-sectional profile of the guard members is approximately
triangular in shape with rounded corner sections.
12. In a safety razor blade having a flat base structure, and an
elongated cutting edge integral with a side of the razor blade base
structure, a guarded cutting edge comprising
a multiplicity of separate elongated metal thread-like guard
members bent into substantially V-shaped form wherein each guard
member defines a pair of relatively short ends converging at a
rounded corner section, the guard members being fitted over the
blade cutting edge and spaced substantially equidistantly apart
along the blade cutting edge with their rounded corner sections
protruding forward of the blade cutting edge,
each guard member having a diameter in the range of between about
0.0015 to 0.0050 inch, the spacing between adjacent guard members
being in the range of between about 0.02 and about 0.06 inch,
and
means for independently providing rigid and permanent attachment of
the respective ends of each guard member to the razor blade base
structure at points relatively close to the blade cutting edge to
support the guard members in a substantially fixed position in
which lateral movement of the guard members relative to the blade
cutting edge during normal shaving operations is substantially
prevented.
13. A guarded cutting edge according to claim 12 in which the
effective length of each guard member is in the range of between
about 0.03 and 0.06 inch.
14. A guarded cutting edge according to claim 12 wherein the edge
of the razor blade base structure defines a pair of flanks
converging outwardly to a point, and wherein the respective ends of
each guard member are permanently secured to the respective flanks
of the blade base structure.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to razor blades, and more particularly to a
razor blade with a guarded cutting edge which reduces the chances
of cutting the skin during shaving.
2. Description of the Prior Art
In the past, safety guards have been applied to the cutting edges
of razor blades to reduce the chances of cutting the skin during
shaving. The prior art safety guards ordinarily include a plurality
of longitudinally spaced metal segments or guard members protruding
forward of the blade cutting edge to shield the skin from the
cutting edge during shaving. Some prior art safety guards have been
unsatisfactory because they are costly to manufacture on a large
scale. Others have been unsatisfactory because they can only be
used in combination with a specifically constructed razor blade
holder. However, the chief disadvantage of the prior art safety
guards is their inability to significantly reduce the chances of
cutting. For example, the guard members of some prior art safety
guards are relatively fragile and are not supported in a direction
parallel to the blade cutting edge. During shaving, forces
ordinarily occur in a direction parallel the blade cutting edge,
and these forces tend to deform the guard members. Since the guard
members are relatively fine, they tend to move relative to the
blade cutting edge during shaving, thereby altering the spacing
between them. In addition, the guard members often become damaged
or cut during shaving. Other prior art safety guards do not have
their guard members spaced properly to prevent the chances of
cutting. For example, some of the prior art guard members are
spaced relatively far apart, essentially because of the belief that
a substantially large number of guard members impairs shaving
efficiency. Large spacing between guard members, however, causes
the skin to bulge excessively between the members, which can result
in cutting of the skin. Some prior art safety guards function
merely as spacers, for maintaining a vertical space between the
longitudinal cutting edge of the blade and the body of the blade
holder mechanism. These safety guards keep the blade spaced a
slight distance away from the skin during use, but cutting of the
skin can still result rather easily when holding the blade at
certain angles relative to the skin, or when the blade is drawn
across the face in a direction parallel to the blade cutting
edge.
SUMMARY OF THE INVENTION
The apparatus of this invention provides a razor blade with a
guarded cutting edge that significantly reduces the chances of
injury to the skin during shaving. The structure of the cutting
edge is relatively simple, and therefore can be manufactured at a
relatively low cost. Moreover, the razor blade can be used
interchangeably with conventional razor blades in a conventional
razor blade holder.
Briefly, the guarded cutting edge contemplates an elongated razor
blade edge, and a multiplicity of relatively thin elongated guard
members bent into substantially V-shaped form and fitted over the
blade edge. The guard members are spaced substantially
equidistantly along the length of the blade edge. Each V-shaped
guard member has a pair of relatively short, elongated ends
converging at a rounded corner section, and the rounded corner
sections protrude forward of the blade edge. The respective ends of
the guard members are permanently secured in close proximity to the
blade edge to provide an effective means of support for the guarded
members. Preferably, the respective corner sections of the guarded
members are permanently secured to the blade edge to provide
additional means of support.
In the preferred form of the invention, the ends of the guard
members are secured either to respective flanks of the blade
cutting edge or very close thereto. Preferably, the guard members
are supported laterally along the length of the blade edge by
producing a tight friction fit between the inner contour of the
corner sections of the guard members and the blade edge.
This invention further contemplates a method of constructing a
guarded razor blade cutting edge which includes a multiplicity of
relatively short and thin, deformable filaments longitudinally
spaced along the blade edge of a razor. The method contemplates
that the hardness of the blade edge is greater than that of the
filaments, and includes the steps of supporting each filament in a
relatively straight form substantially perpendicular to the blade
edge of the razor, and moving the supported filament and blade edge
relative to each other to bend the filament over the blade edge,
using the relative hardness of both to slightly deform the filament
to thereby clamp it to the blade edge. The end portions of the
filament are then secured in close proximity to the blade edge.
The guard members contemplated by this invention are held rigidly
in contact with the razor blade edge during the shaving, because of
the support provided at their ends. As a result, movement of the
guard members relative to the blade edge during shaving is
substantially prevented. Furthermore, the support means permits the
guard members to be made relatively thin which improves the quality
of the shave. In use, when the guarded cutting edge of this
invention is pressed against the skin, the skin bulges between the
protruding corner sections of the guard members toward the razor
blade edge. The guard members contemplated by this invention may be
configured and arranged, depending upon a user's beard and skin
characteristics, so that the bulging skin between each of the guard
members barely touches the blade edge when moderate pressure is
applied to the razor blade holder mechanism. Thus, the chances of
cutting the skin are substantially prevented, regardless of the
cutting angle of the blade edge, and even though the blade is
accidentially drawn across the skin in a direction parallel to the
blade cutting edge.
BRIEF DESCRIPTION OF THE DRAWINGS
The features of specific embodiments of the best mode contemplated
of carrying out the invention are illustrated in the accompanying
drawings, in which:
FIG. 1 is a schematic plan elevation of a conventional safety razor
blade with the guarded cutting edge of this invention;
FIG. 2 is an end elevation taken on line 2--2 of FIG. 1;
FIG. 3 is a schematic sectional elevation taken on line 3--3 of
FIG. 2;
FIG. 4 is a schematic sectional elevation showing an alternative
embodiment of the guarded members of FIG. 3;
FIGS. 5 and 6 are fragmentary end elevations of a razor blade edge
and guard member at various stages of the method contemplated by
this invention;
FIGS 7 and 8 are fragmentary end elevations of a razor blade edge
and guard member illustrating alternative forms of the method;
and
FIG. 9 is a fragmentary sectional end elevation of a conventional
razor blade holder and a safety razor blade with the guarded
cutting edge.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
Referring to FIGS. 1 through 3, a guarded cutting edge 10 is formed
along each side of a conventional double-edged safety razor blade
11. A pair of elongated flanks 12 integral with the sides of razor
11 converge outwardly to an elongated blade edge 14. Cutting edge
10 further includes a multiplicity of relatively short and thin
guard members 16 bent into substantially V-shaped form and fitted
over blade edge 14. The guard members are preferably spaced
substantially equidistantly apart along the length of blade edge
14. As seen best in FIG. 2, each guard member 16 defines a pair of
elongated ends 18 converging at a rounded corner section 20.
As contemplated by this invention, guard members 16 are relatively
short in length and relatively thin in transverse cross-section.
Further, the guard members are spaced relatively close to each
other along the length of blade edge 14. This cutting edge
configuration is not readily apparent from the drawings because for
clarity reasons, the drawings are not shown to scale. In
particular, guard members 16 are shown greatly exaggerated in size
and reduced in number. The invention contemplates that the actual
width of guard members 16 and the actual length of the spacing
between the guard members both vary depending upon the thickness of
a user's beard and the user's particular skin characteristics. The
basis for choosing a suitable blade cutting edge configuration is
hereinafter described. However, an appreciation of the dimensions
of the invention can be had at this point by realizing that an
average whisker of a beard is approximately 0.004 inch thick. A
practical range of dimensions for guard members 16 is about 0.0015
to 0.008 inch for the diameter of the guard member, and about 0.03
to 0.06 inch for the length of guard member 16 before bending. It
has been found that a substantial number of guard members can be
secured to a razor blade edge without significantly impairing
shaving efficiency, and that such an arrangement of guard members
substantially reduces the chances of cutting during shaving. A
practical range for the spacing between guard members 16 is about
0.015 to 0.08 inch. It is to be understood that these dimensions
are given by way of example only, and that deviations from these
dimensions are possible without departing from the scope of this
invention.
As seen best in FIGS. 7 and 8, guard members 16 are held
permanently in contact with blade edge 14 by welding the respective
ends 18 of the guard members to corresponding flanks 12 of blade
edge 14. FIG. 7 shows each end 18 of guard member 16 secured to a
flank 12 by a weld 22 placed close to the upper edge of each flank
12. FIG. 8 shows an alternative configuration wherein each end 18
of guard member 16 is secured to blade 11 by a weld 24 placed
slightly beyond the upper edge of each flank 12. Besides welding,
an alternative means for securing guard members 16 to blade edge 14
includes brazing, soldering, or bonding. As seen best in FIG. 3,
the respective front ends of guard members 16 are supported in a
lateral direction parallel to the blade edge 14 by placing each of
them in a respective shallow notch 26 formed in blade edge 14. When
guard members 16 are secured to blade edge 14, the guard members
are maintained in a rigidly fixed position relative to the blade
edge during shaving. Thus, the guard members are able to withstand
normal laterally directed forces resulting during shaving
operations without being damaged or deformed relative to blade edge
14. Consequently, the spacing between the guard members is
maintained relatively uniform during shaving.
A method for providing lateral support for guard members 16
contemplates using the blade edge 14 of razor 11 as a male bending
die. The method includes the steps of supporting guard members 16
in a straight form substantially perpendicular to blade edge 14,
and then bending the blade members around blade edge 14. This
method allows the depth of notches 26 to be controlled by an
appropriate choice of factors such as: (1) the hardness of blade
edge 14; (2) the hardness of guard members 16; (3) the included
angle between blade edge flanks 12; and (4) the direction,
symmetry, and lever arm of the applied bending forces. The guard
member 16 has a hardness less than that of the blade edge. If the
guard member is relatively hard compared with the blade edge, and
if a small included angle exists between flanks 12 of cutting edge
14, a large bending force at a short bending arm produces a
relatively deep notch in the blade edge. Since the included angle
between the flanks of cutting edges of most conventional safety
razor blades is rather small, the notches formed by this method can
become so deep as to prevent guard members 16 from protruding a
sufficient distance forward of blade edge 14.
FIGS. 5 and 6 show a preferred method for obtaining a relatively
shallow notch in blade edge 14. The first step of the method is
illustrated in FIG. 5, in which small bending forces F.sub.1 are
applied to the ends of guard member 16 in the directions
illustrated by the arrows. A substantial component of each force
F.sub.1 is used to produce bending of guard member 16 from an
initially straight position (not shown) perpendicular to blade edge
14 to the position shown in FIG. 6. The resulting force produced by
guard member 16 on cutting edge 14 during this step is therefore
relatively small. FIG. 6 shows the second step of the method
wherein relatively large bending forces F.sub.2 are directed
substantially perpendicular to flanks 12 of cutting edge 14. Since
the component of forces F.sub.1 and F.sub.2 directed against
cutting edge 14 in the direction parallel to blade 11 is relatively
small during the two steps illustrated in FIGS. 5 and 6, the notch
26 formed in blade edge 14 is relatively shallow, as shown in FIG.
7. The formation of the notch 26 is aided by an asymmetrical
application of forces F.sub.1. FIG. 7 shows the final step of the
method in which the ends of guard members 16 are welded to flanks
12 of cutting edge 14 by a weld 22.
FIG. 8 shows an alternative method for providing lateral support
for guard members 16. This method contemplates using a guard member
having a hardness much less than that of blade edge 14, with a
sufficiently large included angle between flanks 12 of blade edge
14. During the bending process for this method, symmetrical bending
forces are used to bend guard members 16 over blade edge 14. The
result of this method is that a notch 28 is formed at the inner
contour of rounded section 20 of guard member 16 by the penetration
of blade edge 14. Guard member 16 is thereby clamped tightly to
blade edge 14.
FIG. 9 shows a conventional safety razor blade 11 with the guarded
cutting edge 10 of this invention mounted in a conventional safety
razor holder 29 which includes a bottom blade clamping member 30, a
top blade clamping member 32, and an elongated upwardly extending
handle 34. In use, when blade holder 29 is pressed against a skin
surface 36, the skin bulges upwardly between each of the guard
members 16 toward the portion of blade edge 14 between respective
pairs of guard members 16, as shown by the upwardly bulging skin
surface 38. By suitable choice of the size of guard members 16 and
their spacing, depending upon the skin and beard characteristics of
the user, moderate pressure applied to razor holder 29 against skin
surface 36 can cause the skin surface 38 between guard member 16 to
bulge a predetermined amount so that it barely, or not at all,
touches blade edge 14. Thus, razor holder 29 can be drawn across
the skin with sufficient pressure so that a wisker 40 is shaved off
at skin surface 38. The chance of cutting the skin by the blade
cutting edge 10 during shaving is thereby substantially prevented.
Razor holder 29 can be drawn across the face at various angles
relative to the skin, yet guard members 16 prevent blade edge 14
from penetrating into the skin far enough to cause cutting. In the
event razor holder 29 is drawn across the skin in a direction
parallel to blade cutting edge 10, the finely spaced guard members
16 substantially prevent blade edge 14 from penetrating the skin.
This result is accomplished because the outwardly protruding guard
members 16 are spaced very close to each other, with the result
that the bulging of the skin between the guard members can be
controlled by the pressure applied to razor holder 29.
Guard members 16 are relatively short, with the result that the
ends 18 of the guard members are secured to the flanks 12 of blade
edge 14 of razor 11, or very closely thereto. Thus, when the razor
11 is mounted for use in razor holder 29, the ends of the guard
members do not interfere with clamping members 30 and 32, as seen
in FIG. 9.
FIG. 4 shows an alternative form of the invention in which a
multiplicity of relatively short and thin guard members 42 are
secured to blade edge 14 of razor 11 in a manner similar to guard
members 16. Guard members 42 are relatively triangular in
cross-section with rounded outer corners 44. This configuration
avoids injury to the skin in the same manner as guard members 16,
but also results in a fewer number of whiskers or hairs being bent
instead of being cut during shaving.
The guard members 42 can be constructed from pre-manufactured
triangular wire. Alternatively, they can be formed into the
triangular shape from conventional round wire. This is done by
deforming the initially round wires in a corresponding set of
rollers disposed in close proximity to the location where the guard
members are permanently secured to the blade. This method
eliminates the otherwise difficult problem of orienting the guard
elements and the blade about their respective longitudinal axes in
relation to each other before permanently securing them to each
other. A further advantage is that conventional round wires are
less expensive and easier to procure than profile wires.
The end portions of blade edge 14 may occasionally be exposed to
greater mechanical forces than its central portions during shaving.
Thus, to reduce the chance of injury to the skin potentially
inflicted by the end portions of the blade edge, outer guard
members 46 at the end portions are spaced closer together than the
remaining guard members 42, as shown in FIG. 4.
Teflon or other similar low-friction material is applied to guard
members 16 to reduce skin-friction developed when moving blade
cutting edge 11 over the skin during shaving. The coating may also
cover the flanks 12 of cutting edge 14 in a manner well known in
the art.
* * * * *