RAZOR BLADE UNITS AND BLADE SPACERS THEREFOR

RASOIRS A LAMES INTEGREES ET ESPACEURS DE LAMES

English Abstract

In or for use in a razor blade unit having two parallel blades (14) and an interposed spacer (15), a flexible spacer having
spaced transverse ribs with the ribs on one side offset from the ribs on the other side.

French Abstract

Dispositif d'espacement flexible, conçu pour une lame de rasoir constituée de deux lames parallèles (14) séparées par un dispositif d'espacement (15). Les deux côtés du dispositif d'espacement comprennent des cannelures transversales, les cannelures d'un côté étant décalées par rapport à celles de l'autre côté.

Claims

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE PROPERTY OR
PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. In a razor blade unit including:
a first flexible blade with an edge and having a length
and a width and a bottom surface;
a second flexible blade with an edge and having a length
substantially equal to the length of said first blade and having a
width and a top surface;
said first blade bottom surface and said second blade top
surface disposed in facing relationship and said edges of said
blades facing in the same direction and aligned generally parallel
to one another; and
a spacer disposed between said blades and having a
generally rectangular cross-section with a top, bottom, front, and
back surface, said top surface facing said first blade bottom
surface, with said bottom spacer surface facing said second blade
top surface with said front spacer surface facing in the same
direction as said edges;
said spacer having a length about equal to the length of
said blades and having a width;
the improvement comprising:
said spacer being flexible about an axis generally
parallel to the longer dimension of the rectangular cross-section
of said spacer;

a plurality of ribs integral with said spacer and spaced
along the top thereof, each rib having the same height;
a second plurality of ribs spaced along the bottom of
said spacer each having the same height and offset between said
top ribs;
said blades, when assembled into the blade unit, having a
desired separation between said facing blade surfaces less than
the thickness of said spacer plus the thickness of the top rib and
the thickness of the bottom rib;
when said spacer and two blades are spaced the desired
distance apart in close contacting relationship, said spacer
deforms along its length to form a serpentine shape with said top
and bottom ribs touching the respectively opposed bottom surface
of said top blade and top surface of said second blade.
2. In a razor blade unit according to claim 1, the
thickness of the spacer including the top and bottom ribs is
greater than the desired separation of the blades by less than the
height of a rib.
3. In a razor blade unit according to claim 1, one of
the front and back surface of the spacer is formed with spaced
teeth lying in the plane of the spacer.
4. In a razor blade unit according to claim 1, the
spacer is formed of polyethylene.
5. The razor blade unit of claim 1 further including at
least two protrusions on each of said top surface and said bottom

surface of said spacer, each of said protrusions having a height
and having a length in a direction along the length of said
spacer;
said first blade having recesses in its bottom surface
aligned with said spacer protrusions;
said second blade having recesses in its top surface
aligned with said confronting protrusions from said spacer;
said blade recesses having a length greater than the
length of its corresponding protrusion;
so that as said blades flex said protrusions are free to
move along said recesses to allow each blade and said spacer to
bend as a unit while allowing relative translational movement
along the length of the spacer among said first and second blades
and said spacer.
6. A razor blade unit according to claim 1 further
including a molded plastic housing providing a guard portion and a
cap portion between which said first blade, said spacer and said
second blade are clamped under compression to form a razor
cartridge.

Description

W092/06828 PCT/US91/07598
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2091~7
Razor Blade Units and Blade Spacers ~herefor
This invention is concerned with spacers for
flexible razor blade units comprising two blades in
t~n~; , with flexible razor blade units comprising such
sp~s~rs, and with safety razors comprising such blade
units.
Tandem razor blade units which are flexible,
in response to forces ~ o~ Lered during n~. -1 use,
about an axis or axes parallel with the plane of the
blades and ext~n~;ng substantially perp~n~;c~-arly to
the cutting edges of the blades have been described in a
number of patent specifications, for example, British ;.
Specifications 1589591 and 2119690.
The flexibility:of such a blade ~nit can be
assured by the design of the moulded plastics housing in
; which the blades and spacer are mounted, by the use of
hl~ which are ~h;nn~r than co,.~er,Lional, and by the
. design and material of the blade spAcer. The spacers
which are conventionally used in non-flexible blade
. 20 :units are~formed of 0.02-inch (0.51 mm) thick aluminum;
:~ : the use of such a sp~c~r in a blade unit which was, in
other respects,--:flexible would stiffen it to such an
- extent that it would not flex in shaving and it has
:- accordingly been .~cc-J..i~e~ that in a flexible blade
-~25 unit, the 6p~cer sho~ be made of a~flexible, '
preferably plastics, material. -~~.~-~;; - :-
p ,~ -We have now developed sp~c~rs which-provide
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W O 92/06828 PC~r/US91/07598 2 0 9 1 ~ 7 1
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tAn~ razor blade units with improved flexibility.
According to the present invention, there is
provided a spacer for a flexible razor blade unit
comprising two blades in tAn~ , which comprises a
flexible plastics strip having a length and width
appropriate to the blades with which it is to be used,
the major surfaces of the strip being formed with
transverse ribs, the ribs on one side of the strip being
offset with respect to those on the other side and the
thir-kn~sc of the strip and two ribs being greater than
the desired separation of the hl A~
According to another aspect of the invention,
there is provided a flexible tandem razor blade unit,
which comprises a flexible moulded plastics housing
providing a guard portion and a cap portion and in which
tandem blades and a sp~cer according to the invention
therebetween, are clamped under compression.
In such a unit, the guard portion and the cap
portion preferably have a comb-like form, the teeth of
the two comb-like portions being inte~ r~cLed by a web
which is sufficiently thin as to be flexible.
: According to a further aspect of the
invention, there is provided a safety razor comprising a
flexible tAn~- blade unit according to the invention, a
handle, and co~ P~Ling means c~, e~Ling the blade unit
- to the handle which means permit flexing of the blade
unit. - ~
: The spacer according to the invention is
preferably formed of polyethylene. In addition to its
30. cheArnPss and good moulding properties, polyethylene has
-!'. the advantage of a very low coefficient of friction
;against steel so that the hlad~r can move easily against ,,
the spacer as the blade unit ~s flexed. It is preferred
that the height of the ribs ~ be such that the
th~içknPss of-the strip-and two ribs should be greater
than the desire separation of the blades by less than
the height of a rib.
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W092/068~ PCT/US91tO7598
,; 2~a~7~
- 3 -
For the better unders~n~;ng of the invention,
a currently preferred ~ nt thereof will now be
described, by way of example, with reference to the
J a_- -nying drawings, in which:
Figure 1 is a ~el~e~ive view of a flexible
tandem razor blade unit which also show the blades and
Rp~ser thereof prior to acs~ 'ly in the unit,
Figure 2 is a partial longit~ n~l section of
the spacer shown in Figure 1, and
Figure 3 is a partial longit~in~l section of
the bl~s and spacer shown in Figure 1 as cl~mre~ in
the unit.
Referring to the drawings, a flexible t~n~
razor blade unit 10 comprises a flexible moulded
plastics housing 11 providing a guard portion 12 and a
cap portion 13 and in which tandem hl~e~ 14 and a
sp~cer 15 therefor, are clamped under compression. The
spAcer 15 is a flexible plastics strip 16 of moulded
polyethylene having a length and width ap~l~p,iate to
the blades with which it i8 to be used, for example, a
length L of 37.50 mm and a width W of 2.04 mm. Both
sides of the strip are provided with integrally moulded
transverse ribs 17, the ribs on one side being offset
with respect to those on the other side (see Figure 2).
One long edge of the strip 16 is provided with sp~ce~
teeth 18 lying in the plane of the strip.
In a part~ r embodiment the ribs 17 are
separated from each other by a distance P of 2.5 mm, the
thiç~n~ss T1 of the strip 16 is 0.30 mm and thiçkn~s;s T2
of the strip and two ribs is 0.51 mm, so that the height
of each rib is 0.105 mm.
In this emhodiment~ the spacer is used with
r j I blades 14 having a thir~n~8B of O.0813 mm 80 that the
uncompL-~ssed thir~n~R of the assembly is 0.51 mm + 2 x
0.0813 mm, that is 0.6726 mm. When mounted in the
housing 11 this ~Rse ~ly is compressed to the form shown
in Figure 3 and has a ~h i r~nDss T3 of 0.64 mm, that is

W092/06828 PCT/US91/07598
- 4 -
there is interference of about 0.033 mm to give blade
clamping.
The blades 14 and the spacer lS are retained
in the correct position in the unit 10 by ~LuL,usions
(not shown) in the housing 11 and ~,u~,usions 19 on the
sp~c~r which engage in slots 20 in the blades. Slots
are used so as to allow relative movement of the blades
and spi~cer during flexing.
The offset rib arr~ in the spacer
according to the invention provides good s ~_essibility
and thus facilitates assembly of the blade units and
i ,uves blade clamping. This arran~ L is also such
that friction beL~en the spacer and the blades during
flexing is minimized by the fact that the area of
contact is substantially only the surfaces of the
ribs 17.
When the blade unit shown in the drawing is
; connDcted to a handle by means permitting flexing of the
blade unit, it is found that the latter has excellent
flexibility.
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Representative Drawing