U.S. patent number 3,668,030 [Application Number 05/070,434] was granted by the patent office on 1972-06-06 for method of making mating male embossing rolls.
Invention is credited to Frank W. Broderick.
United States Patent |
3,668,030 |
Broderick |
June 6, 1972 |
METHOD OF MAKING MATING MALE EMBOSSING ROLLS
Abstract
A method for manufacture of a male embossing roll which
registers exactly with another male embossing roll, which comprises
forming in the second roll a mating female pattern, filling the
female pattern depressions with resist, and then etching, thereby
to produce a male design corresponding to the female design. The
filling of the preliminarily formed female design by a resist
comprising chrome plating is a preferred embodiment, the entire
roll being chrome plated after the formation of the female design,
the chrome plate then being removed from the surface of the roll
except in those areas corresponding to the depressions in the
female pattern previously formed therein.
Inventors: |
Broderick; Frank W. (New
Providence, NJ) |
Family
ID: |
22095269 |
Appl.
No.: |
05/070,434 |
Filed: |
September 8, 1970 |
Current U.S.
Class: |
216/9;
216/44 |
Current CPC
Class: |
C23F
1/02 (20130101); B23P 15/24 (20130101) |
Current International
Class: |
B23P
15/24 (20060101); C23F 1/02 (20060101); B44n
003/02 () |
Field of
Search: |
;156/14,345 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Steinberg; Jacob H.
Claims
I CLAIM:
1. A method of making a pair of mating male embossing rolls
comprising the steps of:
1. Forming on one roll a desired male pattern;
2. Forming in the second roll a female pattern comprising one or
more shallow recesses mating with said male pattern on said one
roll;
3. Providing etch resist material in said recesses so as to cover
the bottom surface thereof; and
4. Subjecting said second roll to etching until said resist-covered
bottom surfaces project out from the rest of said second roll,
thereby to define a male pattern on said second roll mating with
that on said first roll.
2. The method of Claim 1, in which Step 4 comprises a substantially
continuous etching operation carried on for a period of time
sufficient to cause said resist-covered surfaces to project out
from the rest of said roll for a distance of at least about five
times the depth of said shallow recesses.
3. The method of claim 2, in which said male pattern on said one
roll comprises portions extending out from said roll a given
distance, said shallow recess of said female pattern after Step 2
have a depth no more than one-tenth of said given distance, and
said resist-covered surfaces project out from the rest of said
second roll after Step 4 by a distance of at least about
one-quarter of said given distance.
4. The method of claim 3, in which, in Step 3, said etch resist
substantially fills said recesses.
5. The method of claim 3, in which said roll is metal and said etch
resist comprises a layer of plated metal on said roll.
6. The method of claim 5, in which said roll is plated with
chromium.
7. The method of claim 5, in wich Step 3 comprises metal plating
the recesses and the roll surface around said recesses, followed by
removing said metal plating from the roll surface around said
recesses while leaving said plating in said recesses.
8. The method of claim 7, in which said roll is plated with
chromium.
9. The method of claim 1, in which said male pattern on said one
roll comprises portions extending out from said roll a given
distance, said shallow recess of said female pattern after Step 2
having a depth no more than one-tenth of said given distance, and
said resist-covered surfaces project out from the rest of said
second roll after Step 4 by a distance of at least about
one-quarter of said given distance.
10. The method of claim 9, in which, in Step 3, said etch resist
substantially fills said recesses.
11. The method of claim 9, in which said roll is metal and said
etch resist comprises a layer of plated metal on said roll.
12. The method of claim 11, in which said roll is plated with
chromium.
13. The method of claim 9, in which Step 3 comprises metal plating
the recesses and the roll surface around said recesses, followed by
removing said metal plating from the roll surface around said
recesses while leaving said plating in said recesses.
14. The method of claim 13, in which said roll is plated with
chromium.
15. The method of claim 1, in which, in Step 3, said etch resist
substantially fills said recesses.
16. The method of claim 1, in which said roll is metal and said
etch resist comprises a layer of plated metal on said roll.
17. The method of claim 16, in which said roll is plated with
chromium.
18. The method of claim 1, in which Step 3 comprises metal plating
the recesses and the roll surface around said recesses, followed by
removing said metal plating from the roll surface around said
recesses while leaving said plating in said recesses.
19. The method of claim 18, in which said roll is plated with
chromium.
20. The method of claim 1, in which said roll is metal and said
etch resist comprises a layer of plated metal on said roll.
Description
The present invention relates to the manufacture of a pair of
perfectly mated male embossing rolls.
In embossing, as is well known, sheet material is passed between a
pair of rolls, at least one of those rolls having a design formed
thereon in relief, the pressure exerted by that roll on the sheet
pressed thereagainst deforming the sheet, or at least the surface
of the sheet, so as to produce thereon a corresponding pattern. In
the usual procedure in embossing, both rolls are provided with
designs which mate with one another, one roll being male and the
other female, the sheet material being pressed by the protrusions
on the male roll into the recesses in the female roll, thereby to
be deformed into the surface pattern corresponding to the pattern
on the rolls.
In some instances this type of male-female roll interaction is not
desired. Moreover, in certain of such instances the provision of a
forming pattern on only one roll does not result in proper or
desired surfacing or deformation of the sheet under treatment. For
example, if one of the rolls is smooth and hard and the other is
provided with a pattern, that pattern will be formed only on that
surface of the sheet material which is pressed against the
patterned roll; that surface of the sheet material pressed against
the smooth hard roll will not be embossed. Thus there is a demand
for an embossing operation carried out by a pair of male rolls,
each provided with mating projections which act simultaneously and
similarly on opposite surfaces of the sheet under treatment as that
sheet passes between the rolls. It is essential, however, that the
pattern of projections on both the upper and lower roll mate
exactly. If that is not the case then not only will the patterns on
the opposite surfaces of the sheet under treatment be somewhat
different but, as the registration of the projections on the two
rolls move out of accurate alignment, the sheet under treatment is
apt to be distorted unduly and, indeed, even cut or torn.
The art is well aware of how to make a male roll with a desired
pattern thereon. There are many available known procedures for
doing this, and the choice of the given procedure for that purpose
is determined by manufacturing availability, plant custom, the
particular type of design or pattern involved, the nature of the
material to be embossed, etc., all as is well known to those
skilled in the art. Likewise various methods are known for
producing from a male roll a female roll the pattern of which mates
exactly with that of the male roll. This is conventional in
embossing roll manufacture procedure. However, prior to the instant
invention the art, so far as I am aware, has not known how to make
from a patterned male roll an identically patterned second male
roll. Because no practical way has been known heretofore for
accomplishing this result, the use of a pair of opposed identical
male rollers for embossing has been infrequent and, when tried, has
suffered from drawbacks because of the lack of identity and
accurate registration between the patterns on the two rolls.
It is the prime object of the present invention to provide a method
for making from a pre-patterned male embossing roll a second male
embossing roll which is perfectly mated to the first roll.
It is another object of the present invention to devise such a
method in which the various steps can be carried out accurately and
effectively with existing plant equipment.
It is yet another object of the present invention to devise such a
procedure the steps of which are such as are more or less familiar,
individually considered, to those working in the art, so that the
procedure can be carried out by plant personnel with normal
existing skills.
It is yet another object of the present invention to devise such a
process in which the number of steps required and the time involved
to produce in the second roll a male pattern projecting out to a
desired degree are greatly minimized.
It is a still further object of the present invention to devise
such a method in which the male pattern formed in the second roll
not only registers with the pattern formed in the first roll, but
also accurately conforms to the latter in size, shape and
configuration.
To these ends, a first roll is formed with a desired male pattern
in accordance with known procedures. A second roll, on which the
mating male pattern is to be formed, is first provided with a
shallow female pattern corresponding to the male pattern on the
first roll. This may be done in any conventional manner. At this
point the second roll will have in it a series of indentations or
recesses which accurately register with and conform in shape and
size to the projections on the male roll. These indentations are
then filled with an etch resist material, but the remainder of the
surface of the second roll is not thus resist-coated. The second
roll is then subjected to an etching step, and all of those
portions of the second roll not covered by etch resist are etched
away until the portions covered by the etch resist - the areas
which formerly were the bottoms of the female recesses - project
above the surface of the roll after etching. These upwardly
projecting parts define male projections which are accurately
positioned and shaped in accordance with the position and shape of
the projections on the first roll, and they therefore constitute a
male pattern on the second roll which perfectly mates and registers
with the male pattern on the first roll. Thereafter the etch resist
is removed from the upper surfaces of those projecting portions
defining the male pattern on the second roll, and that male pattern
is then deepened in any appropriate manner in order to provide
projections of desired height.
In a preferred embodiment, the etch resist which is used is chrome
plating. After the second roll has been treated to form the mating
female pattern in its outer surface, the roll is subjected to a
chrome plating treatment whereby its entire outer surface is
chrome-plated. Thereafter the roll is very carefully ground and the
chrome plating removed from the outer surface thereof without
removing the chrome plating from inside the recesses defining the
female pattern. Thereafter, when the roll with the chrome plating
in the female recesses is subjected to an etching operation, that
operation may be carried on for an extended period of time and may
in a single step produce a male projecting pattern of much greater
height than can be produced when ordinary etch resists are used.
This very materially cuts down the overall time to form a male
pattern of desired projecting height, and thus reduces the cost of
manufacture of the roll by a substantial factor, and at the same
time it produces a sharper and more accurate pattern that does the
use of conventional etch resists under ordinary circumstances and
operational procedures.
To the accomplishment of the above, and to such other objects as
may hereinafter appear, the present invention relates to the
manufacture of a pair of mated male embossing rolls, as defined in
the appended claims and as described in this specification, taken
together with the accompanying drawings, in which:
FIG. 1 is a fragmentary cross sectional view of an idealized
embodiment of the first embossing roll with a male pattern formed
thereon;
FIG. 1A is a three-quarter perspective view of the roll of FIG.
1;
FIG. 2 is a fragmentary cross sectional view showing one way in
which the male embossing roll of FIG. 1 may be used to form a
mating pattern in a resist layer on the surface of a second
embossing roll;
FIG. 3 is a fragmentary cross sectional view of the second
embossing roll after it has been subjected to the operation shown
in FIG. 2 and to an etching step, thereby to form therein a female
pattern corresponding to the male pattern on the roll of FIG.
1;
FIG. 3A is a three-quarter perspective view of the roll of FIG.
3;
FIG. 4 is a view similar to FIG. 3 but showing the etch resist
layer removed from the roll;
FIG. 4A is a three-quarter perspective view of the roll of FIG.
4;
FIG. 5 is a view similar to FIG. 4 but showing the roll with a
layer of resist in the form of chrome plating formed thereover;
FIG. 6 is a view similar to FIG. 5 but showing the roll after the
resist layer has been removed from all surfaces thereof except
those in the recesses defining the female pattern;
FIG. 6A is a three-quarter perspective view of the roll of FIG.
6;
FIG. 7 is a fragmentary cross sectional veiw of the roll of FIG. 6
after the latter has been subjected to an etching step;
FIG. 7A is a three-quarter perspective view of the roll of FIG.
7;
FIG. 8 is a fragmentary cross sectional view of the rolls of FIGS.
1 and 7 in the relationship which they will assume during an
embossing operation, the chrome plating having been removed from
the tips of the projections defining the male pattern and the
pattern having been deepened; and
FIG. 8A is a front elevational view, in idealized form, of the
upper and lower rolls of FIG. 8 in operative relationship.
Since the pattern which may be formed on the rolls in question may
vary widely, from one design or letter or series of letters to an
overall surface texture design, no attempt has been here made to
show any particular design or configuration of the pattern.
Instead, the pattern is here shown in stylized form as a single
rectangular projection. This is done in part for ease of
explanation, in part because comprehension of the method steps
will, it is thought, be easier under that situation, and in part
because of the great variety of patterns and designs which can be
employed. Moreover, in the illustrations no attempt has been made
to conform to actual dimensions or to relative dimensions from one
view to another, in part because in actual practice these
dimensions may be very small and in part because exaggerating the
dimensions makes for easier understanding of the explanation. It
should be borne in mind, however, that in making this stylized
showing the problems involved in achieving accurate registration
are to some extent masked. When it is considered that the male
patterning on the rolls may comprise literally thousands of
individual projections in a few square inches of surface, and that
every one of those thousands of projections on a given roll must
accurately mate with correspondingly shaped projections on the
second and cooperating roll, the problems involved in achieving
proper registration and mating will be appreciated. Thus the
simplicity of the illustrations here used belies the complexity of
the problem actually presented to one in the art to whom the task
of making two accurately mating male embossing rolls is
presented.
In accordance with the present invention, and as shown in FIGS. 1
and 1A, the upper male roll, generally designated 2, (the terms
"upper" and "lower" are here used interchangeably) is formed first,
and a male pattern, defined by a projection or projections 4 (only
one is shown, for simplicity of illustration), is formed on its
periphery in any appropriate manner. Two such conventional methods
are the mill and die method and the photoengraving process. For a
given application the projections 4 defining the male pattern must
project out from the body of the roll 2 by a predetermined
distance. A typical such distance is 0.04 inch. The top roll 2 is
then ground so that the outer end surfaces of the projections 4 lie
on an imaginary cylinder true and concentric with the axis of the
roll 2.
It might be thought that a second male roll identical to the roll 2
could be made merely by following the same procedures that were
employed in the manufacture of the roll 2, particularly if those
procedures involved photoengraving. However, that is not the case.
A second roll produced in such a fashion would be, if great care
were taken, a close approximation to the first roll, but as a
practical matter it is impossible to make in that fashion a second
roll which will, over its entire surface area, mate exactly with
the pattern on the first roll.
I have found that an accurately registering second male roll can be
produced in the following fashion: First, as illustrated in FIGS.
2-4, the second roll 6 is provided with a shallow female pattern
which matches that of the male pattern 4. The way in which this can
be accomplished is also well known to the art. One known method, as
illustrated in FIGS. 2-4 is to coat the second roll 6, after it has
been ground so that its outer surface defines a cylinder true and
concentric with the axis of roll 6, with a layer 8 of etch resist
of any suitable composition and then to rotate the roll 6 in
synchronism with the previously formed male roll 2 so that the
protrusions 4 defining that male pattern press into the layer of
etch resist 8, squeezing that material out from those areas
corresponding to the projections 4, as illustrated in FIG. 2.
Thereafter the roll 6, now with a pattern formed in the etch resist
8, that pattern corresponding exactly to the pattern of the male
projections 4 on the roll 2, is subjected to an etching step,
thereby to produce, as shown in FIG. 3, shallow recesses 10 in the
body of the roll 6 immediately beneath the openings 9 formed in the
etch resist layer 8. Thereafter, as shown in FIG. 4, the etch
resist layer 8 is removed, thus leaving the roll 6 with a shallow
female pattern formed by recesses or indentations 10 which
corresponds exactly with the male pattern defined by the
projections 4 on the roll 2.
The next step is to deposit etch resist only in the indentations or
recesses 10 on the roll 6, while leaving the surfaces of that roll
which are not indented free of resist material. This may be done in
various ways, and various types of etch resist material may be
used. For example, as illustrated in FIG. 5, the roll of FIG. 4,
containing the female pattern defined by the indentations 10, may
be covered completely with a layer 12 of etch resist, after which,
as shown in FIG. 6, that etch resist is removed from the outwardly
projecting surfaces 11 of the roll 6, while leaving the resist
material 12 within the recesses 10.
It is preferred, for reasons which will be explained hereinafter,
to utilize chrome plating as the etch resist material for the layer
12. The rolls 6 are generally made of metal, and a layer of chrome
plating can be applied completely thereover in accordance with the
standard manufacturing chrome plating procedures, thus resulting in
the structure shown in FIG. 5. That chrome plating, when deposited,
will conform to the contour of the outer surface of the roll 6,
forming itself in uniform thickness both on the outer exposed
surface 11 of the roll 6 and on the exposed surfaces of the
recesses 10. Thereafter the roll can be machined so as to
accurately remove the chrome plating 12 from the outwardly
projecting portion 11 of the roll 6, thereby leaving the chrome
plating 12a within the recess or indentation 10, as shown in FIG.
6. The machining off of the chrome plating 12 can readily be
accomplished by an accurate grinding operation.
Next the roll of FIG. 6 is subjected to a conventional etching
operation. At that time those surfaces 11 of the roll 6 which are
not covered by the resist layer 12 will be eaten away, but the
portion of the roll 6 beneath the resist layer 12 will not be eaten
away. Hence there will be produced on the roll 6 by this etching
step, as shown in FIG. 7, protrusions 14 extending radially
outwardly from the etch-exposed roll surface 13, the shape of which
protrusions conforms accurately to the shape of the resist layer
12, and thus conforms accurately to the shape of the indentations
10 defining the shallow female pattern originally formed in the
roll 6. Since that female pattern accurately corresponded to the
male pattern defined by the projections 4 on the roll 2, the
projections 14 on the roll 6 will be seen to be accurately mating
and corresponding in all respects (except, at this point, possibly
as to depth or extent of protrusion) to the projections 4 defining
the male pattern on roll 2.
Thereafter the male projections 14 on the roll 6 may be deepened in
any desired manner, usually after the etch resist layer 12a is
removed, in order to produce male projections 14 of desired extent
of protrusion, and then the roll 6 may be used with the roll 2 for
an embossing step, as schematically shown in FIG. 8, with the sheet
to be embossed being passed between those rolls 2 and 6, the upper
and lower surfaces of that sheet being deformed by the male
projections 4 and 14 on the rolls 2 and 6 respectively. Those
projections 11 and 14 are shown slightly separated in FIGS. 8 and
8A to provide space for the sheet to be debossed to pass
therebetween.
With conventional etch resist materials of the type usually
employed in forming a female pattern in a roll as shown in FIGS.
2-4 (e.g. asphaltum) there is a practical limit to the depth to
which etching can be carried out before the etch resist material
becomes sufficiently weakened by the etching operation as no longer
to function reliably as a resist. Etching to a depth of 0.004 to
0.006 inch is usual when such conventional resists are employed;
etching to any further depth is generally considered undesirable.
Thus the greater the depth of etching, the less reliable is the
etching procedure. Accordingly, in forming the recesses or
indentations 10 defining the female pattern initially formed in the
roll 6, etching is carried out to produce indentations preferably
to a depth of 0.0015 to 0.002 inch, in order to insure extremely
accurate correspondance of the indentations 10 to the male pattern
protrusions 4.
If such a conventional resist is used as the resist 12 in
connection with the formation of the protrusions 14 such as those
disclosed in FIG. 7, then the depth to which the etching can be
carried out in any given step, and particularly in the first step,
must likewise be limited to 0.004 to 0.006 inch. However, it is
usually desired that the projections 14 on the roll 6 have the same
height or projecting distance as the projections 4 on the roll 2,
to wit, a depth or height of 0.040 inch. To increase the depth to
desired value calls for additional steps, such as the covering of
the roll with a resist layer newly applied, the use of a mill to
remove that resist layer from places other than the projections 14,
and a subsequent etching step, with each etching step having to be
terminated at a time such as to permit the resist used to continue
reliably to function as a resist. Other deepening procedures are
known and may be used, e.g. machine engraving.
These additional time consuming and costly etch stages can be
minimized when, as has been described above as the preferred
embodiment, the resist used is constituted by a metal plating such
as chrome plating. The chrome plating, in functioning as an etch
resist, is much longer lived in its etch-resist action than more
conventional etch resists. When chrome plating is used as the
resist, a single etching step can be carried out to produce
projections 14 having a height or projecting distance of 0.008 to
0.012 inch. Subjecting the roll to the etchant for a period of time
of about 20 minutes will produce a 0.010 inch depth without any
appreciable loss of accuracy in the configuration of the pattern
formed. It will be apparent that the procedures required to
lengthen the projections 14 from a distance of 0.012 inch to a
distance of 0.040 inch are far less rigorous, time consuming and
difficult than those required when one must start with projections
having a height of only 0.004 inch. Thus the use of the chrome
plating as the resist 12 has many advantages when compared with the
use of conventional resists in this connection.
It will be apparent from the above that the procedure here involved
produces a roll 6 having a male pattern 14 which is an accurately
mating reproduction of the male pattern 4 on the roll 2, and that
the roll 6 is produced by procedures (application of resist layers,
removal of resist from desired areas, and etching) which in and of
themselves are not only known to the art but conventionally used in
plants of the type making embossing rollers. Hence the carrying out
of the present method involves little or no additional investment,
and available skilled and semi-skilled personnel will have the
know-how to carry out these steps without requiring special
training. Thus the method is particularly well adapted for use in
existing plants making embossing rollers. The method not only
produces accurately mating pairs of male embossing rollers, but
does so by means of an inexpensive and thoroughly reliable
procedure.
While but a single embodiment of the present invention has been
here specifically disclosed, it will be apparent that many
variations may be made therein, all within the scope of the instant
invention as defined in the following claims.
* * * * *