U.S. patent number 3,607,485 [Application Number 04/677,205] was granted by the patent office on 1971-09-21 for method of making glass razor blades.
This patent grant is currently assigned to Corning Glass Works. Invention is credited to Alan C. Bailey, Harold E. Camp.
United States Patent |
3,607,485 |
Bailey , et al. |
September 21, 1971 |
METHOD OF MAKING GLASS RAZOR BLADES
Abstract
A blank of vitreous material is accurately ground to a desired
razor blade configuration with specific dimensions, which are a
multiple of the dimensions of the end product as represented by a
predetermined attenuation ratio, and the blank is heated to about
its softening point and drawn down with a desired attenuation to
produce a continuous razor blade ribbon of uniform predetermined
cross-sectional dimensions. The ribbon is then polished in an acid
bath, provided with a lubricating coating, and cut into desired
lengths for packaging.
Inventors: |
Bailey; Alan C. (Big Flats,
NY), Camp; Harold E. (Corning, NY) |
Assignee: |
Corning Glass Works (Corning,
NY)
|
Family
ID: |
24717755 |
Appl.
No.: |
04/677,205 |
Filed: |
October 23, 1967 |
Current U.S.
Class: |
216/53; 216/97;
65/87; 65/31 |
Current CPC
Class: |
B26B
21/58 (20130101); C03B 23/037 (20130101) |
Current International
Class: |
B26B
21/58 (20060101); B26B 21/56 (20060101); B26B
21/00 (20060101); C03B 23/02 (20060101); C03B
23/037 (20060101); C03b 037/02 (); C03c
015/02 () |
Field of
Search: |
;156/24
;65/13,87,31 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
|
|
|
|
|
|
|
1,147,141 |
|
Apr 1963 |
|
DT |
|
648,765 |
|
Oct 1965 |
|
BE |
|
747,759 |
|
Apr 1956 |
|
GB |
|
Other References
"Etching Glass in Acid Baths" O. V. Guzhavin et al. Steklo Byull.
Gosudarst. (1958) cited from Chem. Abs. Vol. 55 (1961)
9817h..
|
Primary Examiner: Burnett; Robert F.
Assistant Examiner: Roche; R. J.
Claims
Although we have set forth the now preferred embodiments of our
invention, it will be apparent to those skilled in the art that
various changes and modifications may be made thereto without
departing from the spirit and scope thereof as defined in the
appended claims.
1. A method of producing glass razor blades comprising, forming a
master glass blank with an enlarged razor blade configuration of
predetermined dimensions having a volume per linear length of from
about 10 to 1,000 times larger than the same per linear length
volume of the desired razor blade, heating such blank to a
temperature approximately corresponding to the softening point of
the glass and sufficient to obtain a glass viscosity of between
10.sup.5 and 10.sup.9 poises, drawing the heated glass blank and
attenuating the same down to a ribbon having a volume per linear
length of from about 1/10 to 1/1,000 of that of the blank while
maintaining the desired razor blade configuration, subjecting the
razor blade ribbon to a polishing solution for providing a
sharpened edge, and applying a coating to the drawn ribbon to
provide a glass razor blade having improved shaving comfort.
2. A method of producing glass razor blades as defined in claim 1
wherein the relative dimensions of the blank and the ribbon are
maintained during attenuation such that the width of the blank is
to the width of the ribbon as the thickness of the blank is to the
thickness of the ribbon.
3. A method for producing glass razor blades as defined in claim 11
wherein the ribbon is subjected to a bath of hydrofluoric and
sulfuric acids.
4. A method of producing glass razor blades as defined in claim 1
wherein the ribbon is alternately polished in an acid solution and
washed in an aqueous solution, a fluorocarbon resin coating is then
applied to the acid-polished glass ribbon, and the coated ribbon is
then cut into razor blades of desired length for packaging.
Description
BACKGROUND OF THE INVENTION
The invention resides in the field of razor blade manufacture, and
particularly is concerned with the specific problems encountered in
the manufacture of glass razor blades.
The state of the prior art is represented by U.S. Pat. No.
2,555,214 to Wallach et al. Basically, as shown in such patent, the
prior art methods consisted of grinding each individual final-sized
razor blade blank to substantially ultimate keenness and then
subjecting the blank to a series of 10-15 immersions of about 5
seconds each in a bath of concentrated hydrofluoric acid. This
known method has not been entirely satisfactory since it is not
only difficult to repeatedly produce a uniform product and control
blade geometry, but also the process is extremely slow since it
requires a relatively long acid-polishing operation to eliminate
the raw grinding flaws. Further, it is virtually impossible to
grind edge configurations other than a conventional V-shaped
edge.
The present invention not only obviates the problem of repeatedly
producing uniform blade structures, but also facilitates the
production of unusual shapes by initially precision-grinding a
large blank to a desired configuration, and then drawing and
attenuating such blank while retaining its relative dimensions to
produce a uniform strip or ribbon of razor blade configuration.
Further, due to the drawing down and attenuation of the previously
ground edge, it is possible to now polish the same in a relatively
short time period. Finally, shaving comfort is obtained by applying
a lubricating coating to the razor blade strip before it is cut
into desired lengths for packaging.
SUMMARY OF THE INVENTION
The present invention sets forth a completely new concept in the
manufacture of glass razor blades by beginning with a vitreous
blank many times the size of the desired finished product, and by
incorporating a controlled redraw operation to attenuate and reduce
the blank to the desired final dimensions. Redraw, as used in the
art, refers to any drawing operation wherein the article being
drawn is initially in a solid state, as opposed to drawing from a
molten bath. By beginning with an enlarged blank having a volume
per linear length of from about 10 to about 1,000 times larger than
the same per linear length volume of the desired final product, it
is possible to form a master blank with virtually any desired blade
configuration due to the ease in handling and machining such a
relatively large size blank. Further, by controlling the
temperature of the blank during the redraw process, the relative
dimensions of the blank are uniformly retained as the blank is
attenuated and reduced in size to that of the desired end product.
Not only does the controlled redraw of the master blank produce
repeatable uniformity of end product along its length, but also any
slight imperfections in the cutting edge are so reduced in degree
during the redraw that only an extremely short acid polish is
required, thus materially reducing the time previously required to
produce glass razor blades. Finally, the lubricating coating
provides the glass razor blade with improved shaving comfort.
It thus has been an object of the present invention to obviate the
tedious prior art process of separately grinding and polishing each
individual razor blade, by providing an improved process of
redrawing a relatively large precision-ground master razor blade
blank into an elongated razor blade ribbon of desired configuration
which is then readily acid-polished for strength and sharpness, and
finally coated with a lubricating media for shaving comfort.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a perspective view in reduced scale of an enlarged or
master razor blade blank which has been precision ground to a
desired configuration with predetermined dimensions.
FIG. 2 is a perspective view of a portion of a razor blade strip
formed by attenuating and reducing the blank of FIG. 1 to a desired
end product, which may have a volume per linear length, or stated
another way, a cross-sectional area of about one-tenth to
one-thousandth of the volume per same linear length, or
cross-sectional area, of the master blank shown in FIg. 1.
FIG. 3 is a somewhat schematic view in elevation illustrating a
continuous process for forming razor blades in accordance with the
present invention.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
An enlarged or master blank 10 is shown having a tapered front face
or facet 12 of desired angle forming a cutting edge 14. The blank
10 is machined, such as by precision grinding, to desired
dimensions so that edge L represents the length, edge T represents
the thickness, and the distance W between edge T and edge 14
represents the width.
Referring now to FIg. 2, a portion of a redrawn razor blade ribbon
10' is shown having a tapered face or facet 12' forming a cutting
edge 14'. The longitudinal edge of the ribbon 10' is shown at 1,
the thickness is shown at t, and the width is shown by w. By
maintaining the proper parameters during the redrawing operation,
the relative dimensions between the master blank 10 and the razor
blade ribbon 10' will remain constant such that w/w=T/t. Further,
the specific angular configurations ground into the master blank 10
will be uniformly retained along the entire extent of the razor
blade ribbon 10'.
Referring now to FIG. 3, a support member 20 is shown having a
clamp 22 for controllably feeding the master blank 10 into an
electrically powered redraw furnace 24. The furnace has an open
portion extending vertically therethrough which is lined with
electric heating elements so as to soften the blank 10 for
attenuation as it passes through such opening. Suitable pulling
means such as driven tractor belts or pull rollers 26 are driven to
draw down and attenuate master blank 10 into razor blade ribbon
10'. The downward drawn ribbon 10' is then preferably transposed to
a horizontal position such as by a suitable idler roller 28, so
that it may be sequentially passed through an acid-polishing bath
30 and a washing bath 32.
It should be noted that the broken lines in FIG. 3 following the
bath 32 indicate that a plurality of alternating acid-polishing and
washing baths may be positioned within the line, depending upon the
speed at which the razor blade ribbon 10' is moving. We have found
that the drawn ribbon blades may be adequately sharpened with as
little as three, 5-second dips in an acid-polishing bath. It is
necessary that the drawn blade be washed in a suitable solution
such as a hot 10 to 500 percent nitric acid solution, after each
dip in the acid-polishing solution, in order to remove the reaction
products and thus produce a smoother and straighter edge.
The preferred acid-polishing bath comprises a mixture of
hydrofluoric acid and sulfuric acid, and although we have
experienced exceptionally good results with a 50 percent solution
of 48 percent grade HF and a 50 percent solution of reagent grade
H.sub.2 SO.sub.4, the particular mixture of HF and H.sub.2 SO.sub.4
may be varied as desired by merely adjusting the acid-polishing
time to the particular solution utilized. In addition, other
solutions such as acetic acid or sodium hydroxide will function to
sharpen the blade edge; however, they do not provide the flaw-free
strenghtened edge produced by the JF and H.sub.2 SO.sub.4 solution.
The period of immersion of the razor blade strip in the 50/50 acid
solution of HF and H.sub.2 SO.sub.4, may vary from about 5 to about
15 seconds, with each immersion being followed by a washing in a
nitric acid solution.
Following the acid polishing and washing operation, the drawn razor
blade ribbon 10' is dried and then dipped into a coating bath or
dispersion 34 to receive a lubricating coating for shaving comfort.
Preferably, a suitable coupling agent, such as a silicone catalyst
produced by the General Electric Company under SC-3963 is applied
to the dried ribbon before coating, to enhance the adhesiveness
between the glass and the lubricating coating. Although various
coatings may be applied, our now preferred coating for glass razor
blades comprises a tetrafluoroethylene fluorocarbon resin such as
produced by the E. I. DuPont de Nemours and Company of Wilmington,
Del., under the trademark Teflon TFE 3170. The coated ribbon is
then cured and cut into blades 38 of desired lengths by cutters 36,
and transported along conveyor 40 for packaging.
The redrawing operation must be carefully controlled in order that
dimensional uniformity and configuration integrity is maintained in
the drawn ribbon. The attenuation ratio between the master blank
and drawn ribbon may vary from about 10 to 100. The upper limit is
merely deemed to be a practical upper limit, whereas poor
dimensional control is evidenced when operating below the lower
limit. Further, we have found that the master blank should be
heated to a temperature approximately corresponding to its
softening point in order to provide the desired dimensional
uniformity. For a glass having a density of about 2.5 g./cm..sup.3,
the softening temperature corresponds to a viscosity of 10.sup.7.6
poises.
Softening point viscosity will of course vary with glasses of
different densities; however, as a general rule we have found that
the master blank may be satisfactorily redrawn at a viscosity of
between approximately 10.sup.5 to 10.sup.9 poises. When the
viscosity drops below 10.sup.5 poises the glass has a tendency to
flow and round out, whereas when the viscosity goes above 10.sup.9
poises the glass has a tendency to distort. When the ribbon is
pulled at high speeds, such as above about 100 inches per minute,
it is of course necessary to provide the furnace with a higher
temperature than the softening point temperature of the glass, so
that the glass itself reaches the softening point as it is rapidly
moving therethrough. The following is set forth as one specific
example of forming razor blades in accordance with the present
invention; however, it is to be understood that such an example is
not limiting in nature.
A master blank was ground to a desired blade configuration with the
blank being 18 inches long, 5.504 inches wide, and 0.200 inch
thick. The glass was fed into a furnace at a rate of one-eighth
inch per minute with the furnace maintained at 910.degree. C., the
softening point of the glass. The glass reached a viscosity of
10.sup.7.5 poises and was withdrawn from the bottom of the furnace
at a rate of 38.3 inches per minute, producing an elongated razor
blade strip or ribbon having a length of 4,284 inches, a width of
0.314 inch, and a thickness of 0.011 inch, thus representing an
attenuation ratio of 17.5. The theoretical ribbon length of 5,500
inch is not obtained due to the fact that a portion of the blank is
retained within the holding clamp and not attenuated.
* * * * *