Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
Background of the Invention
The present invention relates generally to a method
and apparatus for forming and shaping metal, plastic, paper,
fiberboard, paperboard, or the like, sheets or webs in the
assembly and construction of a novel product, consisting of
or comprising an expanded triangularly celled structure useful
per se as a packing material or, when combined with one or more
face sheets, useful in the makeup of packages and containers
for enclosing articles of commerce, or useful as rigid
structural panels in the assembly of various structures, or in
the construction of buildings or manufacture of vehicles or
parts thereof.
At present, one generally accepted method of joining
flat webs of, e.g., paperboard or fiberboard material, to
produce a panel product having a thickness dimension greater
than that of the material employed in its makeup; is the
assembly of so-called corrugated board stock fabricated, for
example, from course fiber kraft material referred to in the
trade as liner board, and a center medium material. This
known product comprises a laminate of two outer liner sheets
bounding a fluted center medium member which is corrugated
by passage through meshing or gear-like cyclinders with
subsequent "take-up" of some 50~ of the length of the medium
in the formation of convolutions therein. Adhesive is applied
to the apex of each convolution of the center medium to
attach the planar outer sheets thereto thus producing a panel
configuration. This known product exhibits rigidity in a
direction parallel to the corrugations or convolutions and is
generally weak in a direction at right angles to these
convolutions.
-- 1 --
There is a broad similarity between the present in-
vention and the production of such corrugated board stock in
that the present invention also contemplates that two outer
liner sheets can be attached to opposite sides of a center
medium sheet after the center sheet has passed between forming
cylinders. In the present invention, however, the center
medium is not corrugated and, instead, is shaped by special
forming cylinders to define an array of triangular, alternately
displaced forms, the planes of the triangles serving to pro-
vide areas for adhesive attachment of the center medium to
the outer liner sheets, and the sides of each triangle being
folded generally perpendicular to the planes of the liner
sheets, thus providing a displacement, or spacing, between
the alternate triangular forms so that their planes alternately
face opposite sides of the center medium.
Like corrugated media, the preparation of the center
medium employed in the present invention is accomplished by
use of gear-like forming cylinders but the cylinder peripheries
are provided with dual-opposed helical tooth arrangements each
of which is broken into a series of triangular elements
engaging complementarily shaped recesses in the opposite
cylinder. Unlike the known corrugating procedure, the method and
apparatus of the present invention effects intermittent cutting of
the web being formed in a plurality of parallel lines
j oriented longitudinal to the web direction. The cuts are
displaced from line to line, thus permitting folding of the
triangular sides of each element without lateral take-up in
the web. The take-up is entirely in the longitudinal direc-
tion of web extension or travel.
A second known method for joining flat sheets employs
a cellular configuration between sheets fabricated by a
f'~.~4
variety of procedures to form so-called "honeycomb" shapes,
the side planes of which are perpendicular to said sheets.
The "honeycomb" edges are attached to the boundary sheets
by bonding means. The product of the present invention is
also broadly similar to honeycomb in that the triangular side
fold of each element or cell provides ribs which are generally
perpendicular to the outer sheet, panel or web, to form
cellular enclosures. However, unlike honeycomb, the base line
of each triangular form in the present invention is cut, to
relieve the web laterally and to provide one open side, thus
permitting the passage of gas or fluid through and between
these cellular members throughout the structure. Moreover,
unlike honeycomb, the forming apparatus and process of the
present invention permits high speed forming and assembly of
the novel product of the present invention in virtually all
materials, employing bonding or mechanical means for connec-
tion of the formed center medium to one or more outer boundary
sheets.
The principal industrial advantage of the present
invention lies in the simplicity of the process with which
the product is achieved. A combination of web handling appara-
tus may be employed, for example, in which three webs pass
from unwind rolls through draw rolls or delivery apparatus
with one web passing through the nip of a pair of forming
cylinders having the dual opposed helical-triangular forms
described earlier, operative to cut and fold the web con-
stituting the center member of the final product, followed
by passage of the formed web to adhesive applicators which
apply adhesive to the flat triangular planes formed on each
side of the formed mechanism, followed by laminating steps
introducing two planar outer webs to opposite sides of the
center member with required heatiny or cooling to bond or set
the adhesive agent used A
The novel forming cylinders used in the present
invention can be mounted in existing corrugated machinery in
place of the conventional corrugating cylinders customarily
used in such machinery. Operational speeds of the resulting
equipment are better than those of existing corrugating equip-
ment however, because of the larger areas afforded for connec-
tion of the outer liner sheets to the center medium. Moreover,
unlike conventional corrugating apparatus, the forming cylinders
of the present invention permit repair without need for replace-
ment of an entire cylinder or even demounting the cylinder
; for this purpose.
It has been found that the cutting and folding pro-
cedures employed in the present invention exhibit substantial
improvements over techniques utilized heretofore in conjunc-
tion with distensible materials that are formed by application
of heat and/or pressure. Such distensible materials lend
themselves to embossing, vacuum forming, and other procedures
involved in the cutting of a web, e.g. like those described
in Koski U.S. Patent No. 3,703,432 issued November 21, 1972,
- where embossing and cutting wheels or cylinders are utilized
which depend upon the utilization of heat, and which effect a
change of guage in the material since the formed shape is
created by drawing material from the adjoining areas.
In the production of the formed panel of the present
invention, the gauge of the material is maintained substanti-
ally constant since the material is merely folded, and since
the folds are accommodated in such a way that a uniform take-
up occurs only in the longitudinal direction of the web. To
achieve such folding, a triangular form must be employed in
which the sides extend along straight lines. Similarly, the
several triangular forms must be identical and must dispose
base lines oppositely and alternately to gather the web
uniformly across the web width. In addition, the cutting and
folding procedures employed in the present invention minimize
the space or intervals between the base line cuts. The space
between adjacent cuts should be approximately one-twelfth the
length of a given cut and preferably never more than 15% or
less than 5% of said length. The radius of the nose or apex
of the triangular form in the plane, as well as in the
perpendicular relationship, must have a diameterequivalent to
this spacing. With such proportioning, the hazard of punctur-
ing the web or causing it to distort objectionably is sub-
stantially reduced. The end result is quite different from
that effected in the aforementioned Koski patent since the
triangular form contemplated therein is not self-accommodating,
and folding of the Koski triangular form, even with the cut
relief in the sheet, is not possible without deforming, dis-
tending or stretching the material. In the present invention,
20 the cuts employed open the sheet and make possible the gather-
ing of the material by the accommodation of the folding in
alternating planes so that the thickness of the combination
thus achieved is a function of the shared fold dimension of
each triangle side.
The base line cuts in the present invention can be
other than a straight line without disturbing the folding
characteristics of the folded side of the triangular shape,
or its formation. A curved cut, or one of "u" shape can, if
desired, by employed, e.g., as an auxiliary means for connect-
ing cover sheets or webs to the folded center panel.
It is accordingly an object of this invention to
produce a board or panel having a central medium of novel
configuration exhibiting isotropic rigidity and strength, with
respect to its plane.
It is a further object to provide such a novel medium
or panel having a configuration adapted to receive additions
of reinforcement within the openings of the medium for the
purpose of enhancing column strength and improving the flat
crush properties of the medium.
It is also an object to provide a novel panel having
a center medium which is reinforced by discs or washers
enclosed within the confines of the dual triangular cells of
the novel medium, to improve column strength and the flat
crush properties of the overall panel.
It is also an object of this invention to provide an
apparatus and process capableof achieving high speed production
.,. ~
;' of board or panels of novel configuration fabricated from any
of a variety of materials and in any of various different
gauges, all by employing generally the same machine configura-
tion.
It is a further object to apply the process of the
present invention in conjunction with known spiral winding
techniques, in the production of individual packaging forms
such as tubs, buckets, barrels and rectangular and square
configurations fabricated of a novel medium.
Another object of this invention is the provision of
a technique which, through the introduction of process
variations achieves a variation in the triangular cell form
size of the novel medium with respect to lateral web direction,
to produce web crescents or arc forms adaptable to the making
of tapered tubs, buckets, cups and other nested configurations.
It is another object to provide a novel forming
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X
apparatus capable of axial adjustment in a longitudinal direc-
tion of one or both cylinders employed in the invention, so
that the triangular base line of each tooth component engages
its adjoining member in controlled shear relationship to that
member. A related object is to provide an apparatus wherein
the shear adjustment is openable to provide for displacement
of material rather than cutting thereof when a web of flexible
plastic material is being formed, thereby to cause the material
to flow under pressure so as to provide a membrane, or a
closed cell form in the formed medium.
It is a further object of this invention to employ
various side fold dimensions of the triangular components of
the formed center member so a variation is spacing between
panels and a variety of widths or gauges can be achieved
without changing the center spacing of the triangular forms
utilized.
It is another object of this invention to provide
,, .
added strength in the combination by reducing the number of
.~
triangular components per unit area in said center panel, or,
conversely, to increase the gauge substantially by enlarging
the size and decreasing the number of triangular components
provided per unit area.
A further object of this invention is to provide an
apparatus that simultaneously cuts and folds a component in
the plane of the web as it passes between two forming cylinders,
thus permitting a gathering or take-up of the web in its
longitudinal direction, while providing relief in the lateral
direction, thus accomplishing diagonal and generally perpendi-
cular folds which are alternately placed in relation to the
direction of web travel.
It is another object of this invention to control
the interval or spacing between longitudinal cuts in the novel
medium, to permit expansion of the sheet by a folding of the
triangular forms produced without tearing or overtly distorting
the uncut areas of the sheet. A further object is to use
contoured surfaces on the periphery of forming cylinders which
are arranged to cut and fold a web in novel fashion thereby
to produce lateral variations in gauge in a given web as it
passes through the forming cylinders.
It is a further object of this invention to produce
a novel product that lends itself to connection by overlapping
and the telescoping of triangular forms within one another to
~; produce a seam in a cylindrical product fabricated from the
, ."
~ formed medium of the present invention.
,. ~
It is a further object to be able to produce a
cylindrical product, fabricated from the formed medium of the
present invention, which will wind on a 45 mandrel, as in
~ spiral winding, or which will wind, as is normal, in line with
;~ the longitudinal direction of web travel.
; It is a further object of this invention to provide
a novel process and product wherein a web is provided with
parallel cuts longitudinally of the web, and wherein the web
material is folded along the cuts while alternating the fold
direction, to produce a series of angular truss-like forms in
which the longitudinal apexes of the resultant forms connect
the formed members to the planes of one or more outer panels
associated therewith.
_mmary of the Invention
The objects of the present invention are achieved
by converting three or more flat fiber, metal or plastic
sheets or webs into a combination panel, the panel having a
flat, tapered or contoured gauge and a dimensional thickness
generally greater than the combined thicknesses of the sheets
employed. The panel is formed by the cutting and folding of
a center sheet member into triangular adjoining shapes,
alternately disposed in parallel rows, each of which is cut
open along its base line while leaving a short connecting
portion of the center sheet to sustain the continuity of the
web, followed by laminating steps in which a pair of planar
outer sheets are affixed to opposite sides of the formed center
sheet.
; 10 The fold, or change from the plane position, in each
triangular formation of the center panel has generally perpen-
dicular sides, but tends to slope in keeping with the draft
characteristics of the triangular tooth components of a pair
of forming cylinders that cooperate with one another to pro-
duce this shape. In the preferred form of the invention, the
sides of the triangle formations are shared to effectively
produce 45 alignment with respect to web directions. The
bases of each triangular formation align in a plurality of
rows extending longitudinal to the direction of the web. The
base line cuts along this line set boundaries with respect
to triangle height. The pattern of the triangular formations
provides alternate planes which are in parallel relationship
to one another, but displaced on opposte sides of the median
line of the center sheet member so these alternate planes
face in opposite directions to establish the gauge perimeters
of the final panel. The arrangement of the triangular side
angles can be varied to form equilateral or isosceles tri-
angles with bases of consequent varied length and resulting
variation in the angle of side alignment disposed across the
web.
The formed center sheet member is combined with two
outer sheets by the utilization of bonding means and laminating
techniques common to the art. An additional cylinder, having a
surface configuration like the pair of cylinders used to form
the center member, can be engaged with the previously formed
center member at one side of the center member to provide back-up
for the application of a first planar outer panel so that full
pressure can be applied during this first lamination step. At
a following station, the combined center medium and first outer
panel can be introduced to the second outer panel by passage
between tWQ plain cylinders under minimum pressure. Unlike
corrugated materials, the compression strength exhibited in the
formed center sheet permits, under most circumstances, a
laminating function in which the two outer sheets are joined
~ to the center member simultaneously without need for internal
c support.
~-; Unlike corrugated materials, the product of the
-~- present invention can be varied substantially by a change inthe tooth configurations of the cylinders employed to form
the center member. The gauge of the first panel, as noted
earlier, is a function of the tooth engagement, or the tri-
angular elements telescoping into one another, at the nip of
the forming cylinders. If the side slope taper of the teeth
is continued so that the tooth height is increased, the panel
gauge is increased proportionately. However it is important
to note that there is no change in the longitudinal take-up
of the web with such an increase in tooth height. The material
taken from the web to produce the thickness of the formed
center medium is taken from the plateau or plane area of each
triangle, and this area can actually be diminished to a point,
thus forming the shape of a half-pyramid, if carried to the
extreme. The fact that longitudinal web take-up is unchanged
-- 10 --
by this variation in thickness of the center medium makes
possible the production of a product which is contoured or
tapered in the lateral direction. This can be done by varying
the height of the triangular components on a profile line
parallel to the axis of the forming cylinder. In similar
fashion a panel of tapered configuration or form can be
` achieved by variation in the triangle height, as well as the
cylinder engagement, along the same profile line.
The forming apparatus used in the present invention
comprises two forming cylinders of special design and shape that
differ from prior art structures. These forming cylinders
comprise surface areas studded with discrete triangular shapes
disposed around the cylinder periphery in a dual-opposed helical
tooth array, dimensionally arranged so each element engages
another in a fashion analogous to gear teeth. A portion of
each triangular element, more particularly its base line, is
placed on one cylinder to engage the inverted identical portion
of a form on the opposite cylinder so that shear occurs when
these two portions engage. As a result, as a web or sheet passes
through the nip or engagement of the forming cylinders, a
series of intermittent longitudinal cuts are formed in the web
as each triangular element engages its mating element in the
opposing cylinder. These longitudinal openings in the web
are on parallel lines that relieve the material laterally while
permitting formation of an angular fold with alternating
opposite angles, thereby to form the two sides of each tri-
angular formation in the web. The triangular pattern produced
in the web defines a generally square grid configuration,
disposed with sides angularly aligned, forming bisecting ribs
generally perpendicular to the plane of the outer sheets.
The specific apparatus form of the cylinders can be
- 11 -
produced in a variety of ways. Each discrete triangular die
element may be made as an individual component and anchored in
suitable openings on the face of a plane cylinder. A second
practical system for the production of such cylinders is to
investment cast steel segments or saddles which are mounted
on the cylinder periphery in adjoining relation to one another.
A third technique is to utilize bar elements, produced
from extremely hard materials such as tool steel, which are
mounted on the cylinder periphery by use of appropriate pins
and/or fasteners. Unlike the discrete tooth component mounting
procedures or those associated with the segment technique,
mentioned above, this third procedure provides a reasonably
sized member which serves better for replacement resulting from
breakage or use damage. This latter form also lends itself to
forging procedures, and machining steps can be minimized prior
to cylinder mounting and the subsequent grinding stage of
manufacture.
Beyond the specific apparatus variations in the
production of triangular forms, and the mounting of such dies
on the periphery of the cylinder, there is the possibility,
described earlier, of variation in the triangular dimensions
to alter the configuration and/or dimensions of the product
being produced. Each triangular tooth form can be shallow
or deep depending upon the desired gauge of the product. An
increase in gauge, however, diminishes the planar areas,
available on opposite sides of the center member, for attachment
to the outer sheet members and weakens the product formed if
the panel gauge is increased to excess. For example, with
three-eighths inch circumferential spacing of triangular forms,
the optimum panel gauge ranges from one-eighth of an inch to
three-eighths of an inch. If greater flat crush and column
- 12 -
. ,r'
, I
strength is desired, the center spacing can be halved or quar-
tered and the triangular forms reduced in size. For larger
forms and heavier gauges, the center distances can be increased,
thereby providing for a proportional increase in the gauge of
the combination.
Another variation provides a different product form.
In this procedure, the two die cylinders employed are conical
or tapered in form but identical in die arrangement to one
.
another, and the two tapered cylinders are mounted for rotation
on angularly placed axial shafts so that their engagement or
nip provides a common line of connection. The discrete tri-
angular die forms or shapes on the cylinder peripheries vary
in size with respect to each increment of diameter so that the
same number of elements are provided in each circumferential
grouping or ring. In this way, the gauge of the web generated
is the same across the cylinder width. Take-up, or gathering
effect longitudinally, is a function of the size of the
triangular form area and is independent of tooth height. The
resulting product takes the form of an arc and curves to a
point of overlap and terminus with respect to a given cylinder
diameterand taper. Thus, each such form will require individual
cylindrical shapes suited to achieve a given dimension. The
purpose of such an apparatus is to produce cups, tubs, buckets,
or barrels suitable for nesting. The medium sheet produced
with th~s procedure must, of necessity, have connection to at
least one outer element to effectively provide the required
enclosure of the cellular form. Such buckets or tubs will
require a disc form for bottoms and a folding procedure to form
edges.
In all of the foregoing description, it has been
contemplated that three sheets or webs are used in the formation
~ t~ 4
of a panel. It will be understood by those skilled in the art,
however, that the single medium configuration, i.e., the formed
"center" member per se, has utilization as a packing material,
or can be applied in a variety of applications to satisfy
various product requirements. It will also be understood that
the medium sheet formed with the triangular-cellular shapes
can be bonded to only a single flat outer sheet for use in
product areas where so-called "single face" corrugated board is
presently employed. Where situations demand spiral winding,
such winding procedures dictate mandrel winding of a plain sheet
followed by application of the single face form for production
of tubes or larger barrel configurations.
Beyond the variations set forth in process and
apparatus to vary product form, an additional configuration
having extreme column and flat crush strength can be achieved
by the addition of a reinforcing component within the cell
openings of the formed center member. In this embodiment of
the invention, a secondary feeder apparatus is provided which
functions, immediately after the formation of the triangular
web configuration, to introduce discs, rings, or washers
equivalent in thickness to the inner gauge dimension of the
formed web, through the upward facing opening at one side of
the sheet so that these added components are forced into the
space provided by the triangular forms that, in their dual
adjoinment, actually constitute a square open area. After
forcing these components into place, the formed combination is
rolled between two rollers to reduce the gauge slightly and
clamp these added components in place. The introduction into
the structure of a disc or ring-shaped supporting member
provides a strength equivalent to that of solid materials.
The use of rings or washer-like components provides
- 14 -
.4
' a lightweight structure and serves effectively in metal applica-
tions. In paper or fiber applications of the invention, discs
of "hardboard" or "cylinder board" also function effectively.
Foamed plastic, plaster, gypsum and other products can also be
introduced in a wet state into the triangular cell openings,
t for reinforcement or other purposes, if required in specific
l~ applications.
t, If the present invention is practiced with certain
plastics or distensible materials that lend themselves to
stretching and strain under pressure, a product variation can
be achieved by adjustment of the "shearing" portions of the
dies used in the forming apparatus. The product produced when
such materials are employed, and when the apparatus is so
adjusted, varies from that described previously in that the
base line "cut" of the triangular form is not actually produced.
By adjustment of the shear engagement between the cylinders,
an opening can be provided in the space between the triangle
base line cutting surfaces to minimize interference between
these planes of engagement, so that a stretched membrane is
produced across what is normally the cut or open area of the
product described previously. This modification is desirable
in certain cushioning and packaging applications where plastic
products are employed and is also effective where a closed
product is required. An example of a material that lends it-
self to this type of treatment is polypropylene. By utilizing
low heat in the order of 175F on the forming cylinders,
stock .020" thick can be drawn across a .125" opening with a
gauge reduction to .006" thus providing a web which completely
closes the area that is normally open in the earlier described
embodiments of the invention.
From the foregoing, it can be seen that substantial
variations are possible in the products and apparatus of the
present invention. Other configurations will be readily
apparent to those familiar with the art.
Brief Description of the Drawings
: The foregoing objects, advantages, construction and
operation of the present invention will become more readily
apparent from the following description and accompanying
drawings in which:
Figure 1 is a plan view of a structural medium con-
structed in accordance with the present invention;
Figure 2 is an enlarged perspective view of a por-
tion of the structure shown in Figure l;
Figure 3 is a perspective view illustrating how the
structure of Figure 2 may be combined with imperforate cover
sheets;
Figure 4 is a view similar to Figure 3 showing how
the medium of the present invention may be utilized in conjunc-
tion with partially perforated, tab-defining cover sheets;
Figure 5 is a cross-sectional view illustrating a
multi-layer product employing media of the type shown in
Figure l;
Figures 6A and 6B show two different cylindrical
products, respectively, fabricated from the medium of the
present invention;
Figure 7 is a view similar to Figure 3 showing how
a product constructed in accordance with the present invention
may be reinforced;
Figure 8 is a detail view of a portion of Figure 7
showing one form of reinforcement element which may be employed;
Figure 9A is a schematic plan view of a medium con-
,. structed in accordance with the present invention employing
- 16 -
triangular forms of varying altitude to produce a web having a
lateral cross section of varied shape;
Figure 9B is a perspective view of a product which is
fabricated utilizing the medium of Figure 9A;
Figures lOA and lOs are cross sectional views of two
different products having varying gauges constructed by use
of media fabricated in accordance with the present invention;
Figure 11 is a partial schematic view of a pair of
forming cylinders adapted to cut and fold a web to produce the
medium of the present invention;
Eigure 12 is a perspective view of two bars having
integral triangular dies, such as may be employed in the
apparatus of Figure 11;
Figure 13 is a schematic illustration of a portion
of one of the dies shown in Figures 11 and 12, depicting pos-
sible variations in configuration of the die;
Figure 14 is a schematic perspective view showing
how tapered forming cylinders, employing triangular dies of
varying size, may be used in the production of a curved medium
of the type shown in Figure 9A; and
Eigure 15 is a schematic view of an apparatus which
may be employed in the high speed production of products of
the type shown, for example, in Figure 3.
Description of the Preferred Embodiments
Referring initially to Figures 1 and 2, it will be
seen that the structural medium of the present invention com-
prises a sheet 10, fabricated of a material such as metal,
plastic, paper or fiber, having a deformed surface defining an
array of closely adjacent projections 11 and intervening
- 30 depressions 12 each of which comprises an integral portion of
the sheet 10 and each of which has a triangular shape in a
- 17 -
¢~! ~L 4
direction parallel to the plane of said sheet. The structure
illustrated is essentially symmetrical in that, when the sheet
is reversed through 180 the regions depicted as projections 11
become "depressions" when viewed from the opposite side of the
sheet, and the illustrated depressions 12 similarly become
"projections" when viewed from said opposite side of the sheet.
The terms "projections" and "depressions" are therefore inter-
changeable in dependence upon the side of the sheet which is
being utilized as a reference.
The edges of each triangular depression 12 are bounded
by the edges of three adjacent triangular projections which are
disposed in surrounding relation to said depression, e.g.,
as depicted in Figure 1, depression 12a is bounded by the
edges of the three projections lla, llb, and llc. Moreover,
as best shown in Figure 2, the sheet of material adjacent at
least two edges of each triangular projection 11 is folded so
as to extend continuously from said two edges in a direction
transverse to the plane of the sheet (essentially orthogonal,
but slightly inclined) to define transverse side walls 13,
14 which merge into the corresponding edges of the adjacent
triangular depression 12 and which are accordingly shared by
each projection 11 and an adjacent depression 12. The third
side of each projection 11, however, does not include such a
shared side wall and, instead, is freely spaced from the
underlying corresponding edge of an adjacent depression 12
by an intervening slot 15. These slots 15, as will become
apparent from the subsequent description, are produced by
shearing the sheet 10 to produce a plurality of aligned, spaced
cuts disposed longitudinally with respect to the web direction
to achieve lateral relief in the sheet so that the side walls
13 and 14 can be folded into their desired configuration
without tearing the sheet or distorting its gauge.
- 18 -
L4
The unslit portion (designated _ in Figure 2) between
the adjacent ends of the cuts or slits (designated b in Figure
2) in each row of slits preferably has a length in the range
of substantially 5% to 15~ of the length of each slit _ to
minimize the space between the cuts while retaining the integrity
of the sheet. The intervals or spaces a between the relief
cuts _ must be proportioned to the size of the parallel tri-
angular spaces of projections 11 and depressions 12 and to the
length of the relief cuts _. Each uncut interval _ must
approximate the horizontal radius _ (see Figures 2 and 13) at
the apex of the triangular form, as well as the radius d
(see Figure 13) in the perpendicular plane of the same apex
point. Additional radii are important to assure appropriate
relief of the material and minimization of friction during
the folding of the shared sides 13, 14, these additional radii
being designated e in Figure 2 and being located at the junc-
tion of each triangular face of a projection 11 and the
adjacent transverse side walls or shared sides 13, 14. The
radius of the nose of each triangular projection 11, at points
below the radius designated c at the extreme apex point of the
triangular face of a projection 11, is of approximately the
same dimension as the radius designated e.
As shown in Figures 1 and 2, the triangular projec-
tions 11 and depressions 12 are each of equilateral form al-
though, as will be appreciated by those skilled in the art,
the principles of the present invention can be employed in
conjunction with triangular forms of different shape. When
the equilateral form is employed, the triangular top surfaces
of the several projections 11 cooperate with the triangular
bottom surfaces of the adjacent depressions 12 to produce
square cellular forms which are separated from one another by
-- 19 --
intervening upstanding ribs (comprising aligned transverse side
walls 13 and aligned transverse side walls 14 respectively as
best shown in Figure 2) that are disposed along intersecting
lines 16, 17 (see Figure 1). This array of upstanding, inter-
secting ribs achieves a grid-like reinforcement of the overall
structure.
The triangular planar top surfaces of the several
projections 11 are, in the embodiment of the invention shown
in Figure 2, disposed in generally coplanar relation to one
another and cooperate to define a first discontinuous surface
comprising one side of the structural medium. Similarly, the
triangular planar bottom surfaces of the several triangular
depressions 12 are also substantially coplanar with one another
and define a second discontinuous surface comprising the other
side of the structural medium. The distance between these two
opposing discontinuous surfaces comprises the gauge of the
formed medium, and this gauge may be a constant throughout the
medium when the discontinuous surfaces are parallel to one
another, or (as will be discussed subsequently in reference
to Figures lOA and lOB) the gauge may vary along the length
of the medium when the discontinuous opposing surfaces of the
medium are disposed in planes which are curved and/or in planes
which diverge away or converge toward one another. The op-
posing discontinuous planar surfaces may~ moveover, be
associated with one or more imperforate or perforate cover
sheets which are adhesively or mechanically attached thereto
to produce a structure which has even greater strength and/or
a continuous outer surface, as may be necessary in certain
applications.
Figure 3 shows an arrangement of this latter type
wherein the opposing discontinuous surfaces of the formed
- 20 -
medium have a pair of imperforate cover sheets 18 and 19 affixed
thereto, e.g., by use of an adhesive applied to the outer
triangular surfaces of each depression 11 and each depression
12.
In an alternative form of the invention shown in
Figure 4, the cover sheets 20 and 21 are each partially
perforated at 22 (in the fashion described in my prior U.S.
Patent No. 3,846,218, only a limited number of such partial
perforations being depicted for purposes of simplicity) to
define tabs 23 which may be bent out of the plane of each
cover sheet into the region between said cover sheets in
adjacent overlying relation to the aforementioned side walls
13, 14 of the intervening center medium. The tabs 23 associ-
ated with cover sheet 20 are, as shown in Figure 4, located
adjacent the outer sides of the several transverse walls 13,
14, whereas the tabs 23 associated with cover sheet 21 are
disposed adjacent the inner surfaces of said walls 13, 14;
and said tabs may be adhesively or mechanically attached to
the facing surfaces of transverse walls 13, 14 to-produce an
overall structure of the type shown in Figure 4 which is not
only reinforced by the addition of the cover sheet but which
is also of ventilating configuration in that air may readily
pass through the entire structure via the several partial
perforations 22 and the gaps between the several triangular
projections and depressions of the center medium.
Various combinations of the structures shown in
Figures 3 and 4 are, of course, possible. For example, only
a single cover sheet, of either perforated or imperforate
form, may be utilized. Alternatively, a pair of cover sheets
may be employed, one of which is imperforate in the fashion
shown in Figure 3, and the other of which is partially
- 21 -
'~
perforated in accordance with Figure 4. When one or more
partially perforated sheets of the type shown in Figure 4
are employed, moreover, the partially perforated sheet may be
attached to the adjacent formed medium at the tabs alone, or
it may also be attached to the center medium by additional
adhesive or mechanical bonding between the cover sheet and the
underlying triangular faces of the projections 11 and
depressions 12.
A still further variation is shown in Figure 5 wherein
a multi-layer structure is produced comprising two media layers
25, 26 constructed in accordance with Figures 1 and 2, which
are separated from one another by an intervening central sheet
27 and which are bounded on their outermost sides by cover
sheets 28 and 29. The several sheets 27, 28, 29 may be
perforate and/or imperforate in accordance with the preceding
discussion, and the strength characteristics of the multi-
layered structure may be varied by varying the disposition
of the projections and depressions in one medium 25 relative
to the projections and depressions in the other medium 26.
Moreover while a two-layer structure has been shown in Figure
5, it will be appreciated that three or more layers can be
provided in analogous fashion in dependence upon the ultimate
application of the structure.
The medium shown in Figures 1 and 2 may be bent into
cylindrical form when a product of that shape is desired, and
the overlapping ends of such a cylindrically-shaped medium may
have their corresponding projections and depressions nested
within one another and affixed together to maintain the
structure in its cylindrical configuration. The cylindrical
form can assume the arrangement shown in Figure 6A in which
the several relief cuts and the resulting slots 15 of the
-- 22 --
medium are disposed along lines which are parallel to the axis
of the cylinder so that the rib lines 16, 17 (Figure 1) are
disposed on 45 intersecting lines 16a, 17a with respect to the
cylinder axis. Alternatively, as shown in Figure 6B, the medium
may be so wrapped that the several relief cuts and the result-
ing slots 15 in the medium are disposed along lines which are
diagonal to the cylinder axis to place the rib lines 16, 17 in
directions which are aligned with and at right angles to the
cylinder axis, respectively.
In those applications where the medium alone does not
exhibit sufficient strength, and where the strength is not
sufficiently increased by the addition of cover sheets thereto,
further reinforcement can be effected by inserting a reinforc-
ing material or a reinforcing component into some or all of the
cells, as discussed earlier. Where such reinforcing elements
are employed, the elements may take the form of discs, rings,
washers or the like. One such arrangement is shown in Figures
7 and 8 wherein a product of the general type shown in Figure
3 has its column and flat crush strength increased by insertion
of ring-shaped elements 30 into the pocket areas formed be-
tween the alternately disposed triangular surfaces of the
: .
several projections and depressions in the formed medium. Each
,l ring 30 extends through one of the aforementioned slots 15
j and includes a portion which underlies the top triangular
surface of a projection 11 and a further portion which over-
lies the upwardly facing bottom surface of an adjacent
depression 12. The edge surfaces of the ring 30 may be in-
clined to conform to the corresponding inclinations of the
intervening side walls 13, 14 described previously. After the
several rings 30 have been forced into place via the afore-
mentioned slots 15, they may be clamped in position by pressing
the various transverse side walls 13, 14 into closely confirming
engagement with the outer edge of the adjacent ring 30. The
introduction of such disc or ring-shaped structures give the
overall medium a strength equivalent to that of a solid material.
The several rings 30 may have an annular configuration
as shown in Figure 7, or they may be solid; and they can be
fabricated of various materials. Instead of providing such
rings, other reinforcing materials such as foam plastic,
plaster, gypsum, etc., can be employed to fill some or all of
the cell openings if required in the specific application.
In the medium shown in Figure 1, the various tri-
angular projections and depressions are all of like size, and
the several projections and depressions are disposed along a
plurality of essentially parallel rows each of which is
occupied by alternately inverted triangular projections and
depressions which are disposed directly adjacent one another.
As a result, the several rows of projections and depressions
are parallel to one another with the distance between each
adjacent pair of rows corresponding to the altitudes of the
triangular projections and depressions, the several slots 15
are disposed along lines which are parallel to one another,
the several transverse sidewalls 13 are disposed along further
lines which are similarly parallel to one another, and the
several transverse sidewalls 14 are disposed along still
further lines which are parallel with one another. In accor-
dance with variations of the invention, however, the tri-
angular projections and depressions which are disposed adjacent
one another in one such pair of rows may have a size different
from the triangular projections and depressions between another
pair of rows so that the spacing between various different
rows differs from one another and the various slots 15, the
- 24 -
various sidewalls 13, and the various sidewalls 14 are disposed
along respective lines which are not straight but, instead,
exhibit a desired curvature. In short, ~y appropriately vary-
ing the sizes of the various triangular projections and depres-
sions throughout the medium, it is readily possible to produce
any desired change in the shape of the medium and, by varying
the heights of the transverse sidewalls 13, 14 throughout the
medium it is also possible to achieve any desired variation in
the gauge (or external surface configuration) of the medium.
These aspects of the invention are shown in Figures 9 and 10.
Figure 9A shows a variant form of medium (which can
be fabricated by an apparatus of the type to be described
hereinafter in reference to Figure 14) wherein the alternating
triangular projections and deprèssions in row 31 are all of
the same height but have a greater height than those in an
adjacent row 32, with the heights of the said alternating
projections and depressions decreasing successively in further
adjacent rows 33, 34, 35, and 36. By reason of this variation
in the sizes of the several projections and depressions, from
row to row, the overall medium has curved edges 37 and 38 due
to the disproportionate gathering of the web material between
said edges 37 and 38. The resultant medium can be provided
with cover sheets, e.g., of the general type described in
reference to Figure 3, and is useful in the production of
tapered cylindrical products of the general type shown in
Figure 9B.
In the arrangements of Figures lOA and lOB the
heights of the various transverse sidewalls 13, 14 are varied
(in accordance with considerations to be discussed herein-
after in reference to Figure 13), in a predetermined manner
to provide a desired variation in the gauge of the final pro-
- 25 -
~" -,~
duct. In the arrangement of Figure lOA, the variation is such
that the outer surfaces of the product are each curved as at
40 and 41. In the arrangement of Figure lOs, the outer surfaces
42 and 43 are each flat, but said surfaces 42 and 43 are
variably spaced from one another to provide the product of
tapered cross section. Combinations of the arrangements shown
in Figure lOA and lOB may, of course, be provided, i.e., by
appropriate control of the heights of the sidewalls 13 and 14
in the medium one boundary surface of the final product may
be curved while the other is flat, and the spacing between
said surfaces may be varied as desired or necessary.
The structural medium of the present invention is
formed, in general, by slotting the planar web of material to
provide a plurality of spaced aligned slits along each of a
plurality of parallel rows, the unslit portion of the web
between adjacent ends of the slits in each row having a length
in the range of 5% to 15% of the length of each slit in that
row (for the reasons previously discussed) and the unslit
portions of the web in each row being positioned opposite slit
portions of the web (preferably opposite the mid-point of
said slit portions) in the adjacent rows. The portions of
the web located along the several slits are depressed away
from the plane of the web into a plane parallel to the plane
of the web while additional portions of the material are
simultaneously folded into planes disposed transverse to the
plane of the web along pairs of lines which extend respectively
from opposing ends of each slit in each row in converging
relation to one another toward an unslit portion of the web
in an adjacent row. By thus slitting and folding the web,
the surface of the web is deformed into an array of closely
adjacent triangular projections and depressions which are
- 26 -
.
disposed in alternately inverted relation to one another between
adjacent pairs of said rows, and from row to row, without
altering the actual gauge of the web material.
The sequence of steps described above can be effected
by use of hand tools or various mechanisms. The steps can be
achieved in high production fashion, by use of a dual-cylinder
cutting and folding apparatus of the type shown in Figure 11.
In the arrangement of Figure lI, a pair of forming
cylinders 50, 51 are mounted for rotation, in opposing direc-
tions and in surface-to-surface engagements with one another,
on a pair of parallel axes 52, 53. The surface of each
cylinder supports a plurality of triangular die elements which
completely cover each cylinder surface (only a very few such
die elements are shown for each cylinder in Figure 11, to
simplify the drawing) with the die elements carried by one
cylinder being oriented in a direction opposite to the die
elements carried by the other cylinder, and with the die
elements on one cylinder being so positioned relative to the
die elements on the other cylinder that, as said cylinders
rotate in opposing directions, each die element on one cylinder
periodically enters and then leaves the triangular space
defined between a cluster of three adjacent die elements on
the other cylinder. A web of material which is fed through
the cylinders at their nip 54 is accordingly formed in the
manner shown in Figures 1 and 2 as the cylinders 50, 51 rotate.
More particularly, referring to both Figures 11 and
12, the surface of each cylinder carries a plurality of
elongated bars 55 which are oriented in a direction parallel
to the rotational axis of the cylinder and which have a length
substantially equal to the axial length of the cylinder sur-
face. Each bar element is mounted in position on its associ-
- 27 -
ated cylinder surface by means of screws 56 and pins 57 which
accurately align the bar elements on a given cylinder relative
to one another, align the bar elements on one cylinder relative
to those on the other, and permit any given bar element to be
readily removed and replaced as a unit if necessary, e.g., due
to breakage of a die element. Each bar 55 is machined on one
surface thereof to provide as an integral part of the bar, a
plurality of axially spaced, similarly oriented, triangular
die elements 58. As best shown in Figures 12 and 13, each
such triangular die element 58 has a flat triangular top sur-
face 58a which is disposed in a plane parallel to the axis
of this associated cylinder, and three side walls which extend
respectively from the edges of said triangular top surface 58a
toward the periphery of the forming cylinder. One of the die
side walls 58b extends in a plane which is substantially
orthogonal to the axis of the cylinder, and the other two die
side walls 58c and 58d extend from the associated edges of
surface 58a in inclined planes which are nonorthogonal to the
axis of the forming cylinder and which diverge from one an-
other toward the periphery of the forming cylinder. The
substantially orthogonal edge 58b of each die on each forming
cylinder cooperates, at the nip of the contra-rotating form-
ing cylinders 50, 51, with another such substantially orthogonal
die surface on a complementary die located on the other form-
ing cylinder, to shear the web which is passing through the
nip of the cylinder, thereby to produce a cut in said web
having a length corresponding to the length of the die surface
58b; and the inclined die surfaces 58c and 58d act to fold
portions of the web extending from the opposing ends of each
such cut into the transverse side walls 13, 14 described
previously.
- 28 -
~'
$~
As best shown in Figure 12, the several bars 55 on
each forming cylinder are so positioned relative to one another
that the triangular dies on one bar are positioned in staggered
relation to the triangular dies on a directly adjacent bar.
The shearing surfaces 58b of the die on each bar are oriented
in a direction at right angles to the axis of the associated
forming cylinder (i.e., they are oriented in the longitudinal
direction of web travel through the nip of the forming
cylinders) and, due to the staggered configuration of the dies
on adjacent bars, the shearing surfaces 58b of dies on alternate
ones of said bars are in alignment with one another.
The dies on the several bars on each cylinder are
disposed in closely adjacent relation to one another in a
plurality of circular rows which extend about the axis of the
associated forming cylinder, and the adjacent apices of the
dies in adjacent ones of said rows are spaced from one another
by a distance in the range of 5% to 15% of the length of the
shear surface 58b of each die. Moreover, the nose of each
die (i.e., the apex opposite to shear surface 58b) is located
adjacent to, but substantially similarly spaced from, the
space between the aligned shear surfaces 58b of the dies in
the adjacent rows so that the dies are clustered in groups of
three to define a substantially triangular space therebetween,
e.g., see the cluster of dies A, B, C and the intervening
space D in Figure 12. It will be appreciated that the tri-
angular space D is oriented in a direction opposite to the
orientation of the dies which define that space, and each
space D is accordingly oriented in the same direction as one
of the triangular dies on the other forming cylinder so that,
as the forming cylinders 50, 51 rotate, each die on one form-
ing cylinder enters the triangular space between a cluster of
- 29 -
:~,
three dies on the other forming cylinder at the nip of the
cylinder, to cause shear engagement between the complementary
surfaces 58b of dies on the two different cylinders while the
inclined surfaces 58c, 58d fold the web material, in the fashion
described previously, into the triangular space D. By reason
of the various dimensional considerations discussed earlier,
this folding is accomplished without tearing the web, and
causes a longitudinal take-up of the web without any lateral
take-up thereof.
By slight axial displacement of the positions of the
dies on one forming cylinder relative to those on the other
forming cylinder, the shearing action accomplished between the
cooperating faces 58b of corresponding dies in the two cylinders
can be changed into a drawing action when the web being formed
is fabricated of appropriate plastic material, to produce a
stretched, comparatively thin membrane across the region between
the cooperating die surfaces 58b, rather than actually cutting
the web in this region. The modified product thus produced has
value in certain applications where it is desirable to utilize
a formed medium which has a completely continuous surface
uninterrupted by cuts or perforations therein.
A further aspect of the invention, useful for example
in the formation of products of the types described in reference
to Figures lOA and lOB, is illustrated in Figure 13. If the
sides 58b, 58c, 58d of the basic die element 58 were to be
extended upwards relative to bar 55, they would intersect at
an apex 60, and the die would have a half-pyramid shape. If
a die of this shape were then reduced in height to the level
designated by the line I-I, the upper surface of the die would
have a triangular shape similar to surface 58a, but of smaller
size. Such a die would, when used in the fashion described
- 30 -
. .
previously, produce a projection or depression in the web
material having a triangular face of smaller size, and trans-
verse side walls of greater height. If the height of the
half-pyramid die is reduced to the levels designated II-II
through IV-IV, each such reduction in height of the die would
correspondingly increase the size of the triangular face of
the deformed web while decreasing the height of the transverse
side walls formed therein. By appropriate selection and
patterning of the heights of the various dies in the forming
cylinders, therefore, projections and depressions of varying
different heights can be produced, to permit the fabrication
of a final product having any desired external gauge, or any
desired variation in external gauge. It will be appreciated
that when the height of the side walls is increased, by a
related increase in the height of the forming die, the material
which is used to provide an increase in height of the trans-
verse side walls 13, 14 is taken from the triangular lateral
face of the formed projection or depression in the web, and
the dimensional variation in the web projection or depression
is accordingly accomplished without any change in the
longitudinal take-up of the web.
Figure 14 schematically illustrates a different type
of forming cylinder arrangement which can be employed to pro-
duce the product shown in Figure 9A. In this modified arrange-
ment, the forming cylinders 65, 66 are each of conical con-
figuration and are mounted for rotation on mutually inclined
axes to accommodate the taper of the cylinders thereby to
produce a parallel relationship between the cylinders at their
nip 67. As a result, the nip provides a vertical plane through
which a web 68 may pass. The surfaces of the two cylinders
65, 66 carry triangular dies of the general type described in
- 31 -
reference to Figures 11-13, but the sizes of the various dies
are graduated to provide smaller dies adjacent the smaller ends
of the two cylinders which progressively increase in size for
dies disposed closer to the larger ends of the two conical
cylinders. The dies on one cylinder are inverted in orientation
relative to those on the other cylinder, to cooperate with one
another so as to achieve the shearing and folding functions
described earlier.
As the web 68 passes through the nip 67 of the conical
forming cylinders 65, 66, a product of the type shown in Figure
9A is produced. The web is cut and folded,to generate a product
having a curvature, caused by variations in the folding func-
tion, which is directly proportional to the number of triangular
dies which are disposed along a given web length. At the
smaller ends of the forming cylinders, more folds are provided
along the edge 68a of the web than are provided at its opposite
edge 68b. The curved product which is produced as a result
is useful in the fabrication of components having a conical
form, e.g., tubs, cups, or buckets having a tapered cylindrical
shape.
Figure 15 is a schematic three-dimensional illustra-
tion of an apparatus which can be employed in the high speed
production of a product of the type shown in Figure 3. The
web material which is to be deformed into the medium of the
present invention is taken from a supply roll 70 and fed by
means of draw rolls 71 through a pair of forming cylinders 72
of the type described in reference to Figure 11. The deformed
medium then passes a glue applicator 73 which applies adhesive
to the lateral triangular faces on one side of the formed
medium. A web of cover sheet material is taken from a further
supply roll 74 by means of draw rolls 75 and is fed through a
14
pair of rolls 76, 77 into contact with the adhesive bearing
side of the formed medium for lamination therewith.
Roll 76, which is used during the laminating step,
can be smooth-surfaced and works in conjunction with the planar
surface of the web taken from roll 74. Roll 77, however, which
is disposed adjacent the deformed surface of the center medium,
may have a surface configuration corresponding to that of one
of the forming cylinders of Figure 11 so that the triangular
projections and depressions on the surface of roll 77 provide
a back-up function permitting full pressure to be applied across
the web width without distorting the projections and depressions
in the center web.
Immediately following the lamination of cover material
74 onto the formed center web, the laminate passes a further
glue applicator 78 which applies adhesive to the opposite side
of the laminate. The other cover sheet material, taken from a
further supply roll 79 by means of draw rolls 80, is laminated
to the opposite side of the product under pressure supplied by
smooth rolls 81. The final panel then passes through a cutter
82 which severs a desired length 83 of the finished product
and stacks the severed lengths as at 84.
While I have thus described preferred embodiments of
the present invention,many variations will be apparent to
those skilled in the art. It must therefore be understood
that the foregoing description is intended to be illustrative
only and not limitative of the present invention, and all
such variations and modifications as are in accord with the
principles described are meant to fall within the scope of the
appended claims.
- 33 -
