Note: Descriptions are shown in the official language in which they were submitted.
WO93J10970. PCT/US~2/10191
` 1 i. ` ~3 ~
TITLE
; APP~ATUS AND PROCESSES FOR FORMING
A HEXAGO~L-Ci~T. HONEYCOMB CORE,
~ AND THE CORE FORMED THEREBY
i~ 5 l~ Field o~ the Invention
The present invention relates to apparatus and
processes for forming a ~exagonal-eell honéyeomb eore, and
3 the honeycomb core f ormed thereby .
2. Descri~tion of the Related Art
De~ices and proce~ses for forming honeycomb half-
, cell structure are known in the art. However, in such
?,~ de~ices and processes, the surface t~mperature of the bars .
which contact the material of which the half-cell structure
is made is often significantly less than the forming
~5 temperatura of the web of material, so that the we~ is
quenched when it comes into con~act with the bars, ~t
, before it is fully formed by the bars. Also, if the web is
not cooled sufficiently before it is disengaged from the
bars, the form imposed by the bars may be partially lost.
~ 20 Moreover, if tension is not maintain?Pd in the unsu~ported
j . web throughout the forming process, accurate formation of
the structure cannot be assured.
Devices and processes for applying adhesive to a
~ corrugated medium are also known. However, a problem
¦ 25 associated with such known devices and processes is that
none of these devices or processes is designed to precisely
1, apply a unifsrm, thin eoating- of adhesive to peaks on a
half-eell structure, and partieularly to peaks on both sides
Q~ the half-cell structure
I 30 In addition, pro .~ses for making a hexagonal-cell
¦ honeycomb csre from a honeycomb half-cPll structure are
known. However, such processes are not directed to applying
a ~irst adhesi~e component to a first group of peaks and
applying a second adhesive compsnent to a second group of
peaks, e~pecially where the first group is on one side of
the half-cell structure and the second group is on the other
W~3/l0970 ~ , 3 ~ PCT/VS92/1019
side of the structure. Moreover, none of the known
processes teach how to handle an adhesi~e-coated honeycomb
tructure, where the coating is sticky from the time the
adhesive is applied until the time the structure is stacked,
and especially where the adhesive is applied to both sides
of the structure before cutting the structure into sheets
for stacking.
Conveyors for advancing a corrugated medium are
known in the art. However, these known conveyors are not
directed to the problem of locating a predetexmined position
at which a secondary operation, such as cutting a web of~
material, is performed, and of stopping the conveyor at a
predetermined pssition after the web has moved past this
position. Moreover, such devices are not capable of
performing a progressi~e removal of the web along the
chains.
In the prior art, devices and processes are also
known for cutting a supply of m~terial into sheets in
preparatiQn for stacking the sheets together. A problem
associated with such kno~n cutting devices and processes is
that the cut to the material is made in about the middle of
a bond area. Accordingly, the blade must contact the
adhesive used to bond the sheets together while the cut is
made. The blade thus accumulates adhesive, which must be
periodically cleaned off. In addition, the ends of the
sheets which are cut along the bond area ~url up as they are
stacked, th~reby exposing the adhesive to end guide plates
which guide the sheets as they are stacked. This causes
sticklng of the sheets and/or contaminates the end guide
plates for the next sheet. In addition, when the sheets
curl up as they are stackPd, the ends of the core must be
cut off in order to align them. This adds complexity to the
process of making a honeycomb core and creates wasted half-
cell structure.
Devices ~or stacking a corrugated medium are also
known in the prior art. However, a pro~lem associated with
W093/10970 ~-~i 2 3 ~ PCT/US97/10191
such known s~acking devicas is that they have configurations
which are complicated, time-consuming and thus expen~ive.
SMMM~RY OF THE T ~ ION
The present invention solves the problems
associated *ith the forma ion of honeycomb half-cell
structure from a continuous supply of material of the prior
art by providing a proce~s and an apparatus for forming
honeycomb half cell structure from a web of material which
pre-heats the me ~anism which positions a length of web, so
that the mechani~ will not quench the web, and which coools
the positioning mechanism and the web before removing th~
web. The present invention further sol~e~ the problems
a~;~ociated with the prior art by providing a process and an
apparatus which maintain the tension of the web while it is
positioned on the mechanism and during the time it stays on
the mschanism, thereby assuring accurate ~ormation of the
half-cell structure. -~~
The present inYention fur~her solves the ~roblems
associated with the prior art by providing an appar~.~s and
a process for applying at least one adhesive component to
the half-cell structure where the structure is held ~ainst
a ba~k-up roll so that the adhesive-coated surface of the
structure is not deformed. The present invention also
solves the problems of the prior art by providing an
appara~us and a process which apply a two-component adhesive
system to oppssed sides of a hsneyc~mb half-cell structure.
The present invention solves the problems
asssciated with Xnown conveyors by providing a system and a
method for advancing the leading edge of a corrugated web
which can automatically stop the conveyor at a predetermine~
position. The present invention also solves the problems of
~he prior art by providing an adva~ciny system and method
which includes a conveyor for holding a cut sheet o~ the web
and which allows fsr prsgressiv2 removal of the cut sheet
3~ ~rom t conveyor.
r,7~
WO93/10970 PCT/US92/lOlgl
''' 1c~,<~ J 9 ~
.
The present invention solves the problems of the
prior art associated with cutting a honeycomb half-cell
structure into a plurality of sheets by providing a process
and an apparatus for cutting a half-cell structure into a
plurality o~ sheets which do not waste hal~-cell structure
and which reduce the possibility of getting adhesive on the
blade as the sheets are formedO The presen't invention also
' solves the problems of the prior art by providing a process
and an apparatus which allow the ends of the shee~s to
lo accurately align as they are stacked. The present invention
also solves the problems of the prior art by providing a ~
honeycomb core assembled from cut sheets made by the process
of the present invention which is simple and economical to
manufacture.
The present invention solves the problems of the
prior art associated with stacking a corrugated medium by
providing an apparatus and a process for stacking sheets of
`~ half cell structure which accurately align the sheets
- without waste as they are stacked to form a honeycomb core,
and that produce a honeycomb core which is accurate and
inexpensive to manufacture.
In order to achieve the foregoing solutions, there
is provided an apparatus for forming honeycomb half-cell
structure from a web of material. The apparatus comprises a
mechanism for positioning a length of the web. The
apparatus also comprises a mechanism for pre-heating the
positioning mechamism to at least the deformation
temperature of the web before the web is placed in contact
with the positioning mechanism and a mechanism for cooling
~ 30 the positioning mechanism to the stabilization temperature
i of the web while holding the web thereon.
Also, in order to achieve the foregoing solutions,
there is provided an apparatus for applying at least one
adhesive component to a honeycomb half-cell structure. The
half-cell structure has a plurality of peaks and valleys on
each side thereof and a diagonal sur~ace between each
lrr
W093/10970 ~ PCT/US92/10191
consecutive peak and ~alley. The apparatus comprises at
lea-~t one gravure roll for coating th~ hal~-cell structure
with the at least one adhesive component and a mechanism for
positioning the half-cell structure against the gravure
roll.
Further, in order to achieve the foregoing
~olutions, there is provided a process for~making a
hexagonal cell honPycomb core from a honeycomb half-cell
structure, where the strueture has a plurality of peak~ and
valleys on each side thereof and a diagonal surface between
each consecutive peak and valley. The process comprises~the
steps of applying a first adhesive component to a firs~
group of peaks and applying a second adhesive component to a
second group of peaks and stacking the structure so thL t the
first group of peaks comes into contact with the second
adhesive component on the second group of peaks, thereby
mixing the components to bond the half-cell structure
together and ~orm the honeycomb core. There is also
provided a h~xagonal-cell honeycomb core made by the process
of the present in~ention.
The present inven-ion also achieves the foregoing
solutions by proYiding a sy~ em and a method f~r ad~ancing
the leading edge o~ a supply of corrugated web having a
plurality of alternating peaks and valleys and for
positioning the web for a secondary operation. ~he system
compxises an endless loop conveying meehanism including a
plurality of spaced support bars for cor.:~cting the valleys
o~ the web, where the conveying mechanism has an entrance
end and an exit end. The system also comprises a holding
mechanism for holdin~ the web against the support bars. The
system further comprises an advancing mechanism ~or
repeatedly advancing the conveying mechanism and the leading
edge sf the web from the entrance end of the conveying
mechanism ~o the exit end thereof ànd a stopping mechani~.
~or repeatedly stopping the adYancing mechanism after a
~!
`~ W093~10970 ~.1 2 3 ~ ~ ~ P~T/US92/tOl9~
, . ................................... ...
~ predetermined number of support bars have advanced past a
;~ position for applying the secondary operation to the w~b.
The pre~ent invention further a hieves the
foregoing solutions by providing an apparatus for cutting a
honeycomb h~lf-cell structure into a plurality of sheets.
The half-cell structure has a plurality of peaks and valleys
and a diagonal surface betw~en each ~onse~u~e peak and
valley on each side thereof. The apparatus comprises a
mechanism for cutting the half-cell structure into a
plurality of sheets and a mechanism for positioning a length
of the honeycomb half-cell structure so that the diagonal,
surfaces of the half-cell structure are positioned adjacent
the cutting mechanism for cutting across th~ diagonal
surfa~P, ther~by forming the sheets. There is also provided
a honeycomb core made by the process of the present
invention.
In addition, in order to achieve the foregoing
solutions, there is provided an apparatus for stacking a
half-cell structure to make a hexagonal-cell honeycomb core.
The structure has a plurality of peaks, a plurality of
valleys and a diagonal surface batween each consecutive peak
and Yalley. The apparatus comprises a stacking mechanism
for stacking the l~yers so that as one layer i5 placed on
the top of a stack comprising at least one layer, the peaks
of one layer contact the peaks of an adjacPnt layer. The
apparatus also comprises a differential pressure mechanism
disposed beneath the top of the stack for reducing the air
pressure surrounding the stack to a pressure bslow the air
pressure on the top of the stack, thereby pressing ~he
sheets together to form the core.
In order to further achieve the foregoing
solutions, there is provided a transfer head for holding at
least one sheet o~ half-cell structure. The transfer head
comprises a plurality of ~upport bars for supporting the
sheet and at least one space formed between each support
bar. The width o~ each space is about the distance between
t
~ WO93/10970 21 23 ~. ~ 9 PCT/vS9?/lol91
adiac2nt valleys of the half-cell structure, and the depth
of the space is greater than the height of the peaks.
BRIEF DESCRIPTION OF THE DRAWINGS
~ ~he ~ccompanying drawings, ~hich are incorporated
¦ 5 in and cons~itute a part of this specification, illustrate
various embodiments of the invention and together with the
description, serve to explain the principles~of the
inventlon .
¦ Fig. ~ is an overall, perspective view of a system
for forming a honeycomb hal~-cell structure from a supply of
, material and for producing a honeycomb core from the half-
; cell structure according.~o the present invention.
Fig. 2 is an exploded view of a corner sectisn of
the assembled honeycomb core of the present invention.
Fig. 3 is a schematic ~iew of a portion of a half-
cell f orming apparatus of the present invention.
~ig. 4 is an enlarged, schematic view of the bars
I and the back-up plates of ~he half-cell forming apparatus of
the present invention.
Fig. 5A is an end view of a portion of a hal~cell
forming apparatus tak~n across lines 5A - 5A of FigO SB.
Fig. 5B is a side vie~ of the half-cell forming
¦ apparatus as shown in Fig. 1.
Fig. 6 is an enlarged perspective view of an
1 2~ adhesive-coated half-cell structur~.
i Fig. 7A is a side view illustrating the
application of first and second adhesive components to the
peaks of a ~alf-cell structure according to an alternative
embodiment ~L the pr~sent invention.
Fig. 7B is a side view illustrating stacking the
hal~-cell structure according to the alternative embodiment
o~ the present inYention shown in Fig. 7A.
Fig. 8A is a side view illustrating the
application of first and second adhesive ~i~mponents to the
peak~ o~ a half-cell structure accordin~ to another
alternative embodiment of the present.invention~
WO93/10970 ,~ PCT/U~92/lOlgl
;:
Fig. 8B is a side view illustrating folding the
half-cell stru~ture according to the other altarnative
embodiment of the pre~nt invention shown in Fig. 8A.
Fig. 9A is an enlarged perspective ~iew of an
adhesive applying apparatus of the present invention as
shown in Fig. 1. --
Fig. 9B is an enlarged portion o~ the half-cell
I structure in contact with a back-up roll and a gravure roll
¦ of the adhesive applying apparatus as shown in Fig. 9A.
Fig. lOA is an enlarged plan view of a portion of
a cutting apparatus of ~he present invention as shown in~
Fig. 1.
Fig. lOB is a cross-sectional view of the cutting
apparatus taXen across lines lOB - lOB of Fig. lOA showing a
plurality of conveyor platens and a stacker axm in position
for picking up a sheet of half-cell structure.
Fig. lOC is a shifted view of the cross-sectional
¦ view of Fig. lOB and showing different platens in position
for cutting the half-cell ~tructure than those shown in Fig.
¦ 20 lOB.
Fig. 11 is a partial plan view taken across lines
11 - 11 of Fig. 12 showing the conveyor and conveyor
positioning sensors ~or locating the half-cell structure at
a blade of the cutting apparatus of the present invention.
Fig. 12 is a cross-sectional view of the channel
o~ the conveyor taken across lines 12 - 12 of Fig. 13.
. Fig. 13 is a cross-sectional view of ~he conveyor
taken across lines 13 - 13 of Fig. 11.
Fig. 14A is a cross-sectional view o~ a stacking
apparatus of the present invention taken across lines 14A -
14A of Fig. 1.
Fig. 14B is a partial cross-sectional view taken
across lines 14B - 14B of Fig. 14A showing the end guide
plates for the csre in a stacX holder of the stacking
apparatus.
WO93~1~970 PCTlUS92/l019l
J~
Fig. 15 is an enlarged cross-sectional ~iew of the
stack holdex of ~ig. 14~ showing the differential pressuæe
zones of the air in the stack holder.
Fig. 1~ is a partial cross-sectional view of an
alternate e~bodiment of the sta~k holder that uses a heated
transfer head on the stacker arm.
Fig. 17 is a timing diagram whichi^n lustrates the
control system logic for operating the system for producing
a honeyco~b core from the half-cell structure.
I 10 DES~RIPTIQN OF THE PREFERRED EMBODIMENTS
, Reference will now be made in detail to ~he A
! present preferred embodiments of the invention, examples of
which are illustrated in the accompanying drawings.
Whenever possible, the same reference numb~_rs will be u~.ed
1~ thr~ughout the drawings to refer to the same parts.
~ Fig. 1 is an overall perspective view of a system,
j shown generally at 10, for forming a honeycomb half-ce`l
3 structure from a supply of material and for producing a
¦ hexagonal-cell honeycomb core from the half-cell st~ucture.
3 20 The individual apparatus of system 10 may be operated in a
stand alone, batch process or in an integrated, over-all
~ process.
7 In accordance with the present invPntion, there is
~ provided a half-cell forming apparatus for making a
1 25 honeycomb half-cell structure from a continuous web of
¦ material. A half-cell forming apparatus is shswn at 20 in
I Fig. 1 which fsrm~ a continuous supply of honeycomb half-
cell struct~re ~rom the material. Apparatus 20 is part of
o~er-all system 10 and will be de cribed in greater detail
30 below. As shown in Fig. 1, apparatus 20 comprises a
continuous web unwind stand, shown generally at 21 in Fig.
1, for storing ~ supply of the material. Web unwind sta~d
1 21 includes a spool 22, a disc 22a, a tensioning rol~
j assembly 22b, and a csnventional brake mechanism (not
35 shown). The brake mech~nism engages disc 22a to resist
unwinding oP spool 22 by tensioning roll assembly 22b.
~ WO~3/10970 ~1 2 3 8 9 ~ P~T~US92/1019l
,.
Thus, the brake mechanism, disc 22a and roll assembly 22b
I maintain tension on the unwinding wob as it is drawn through
half-cell forming apparatus 20. A formed half-c~ll
3 structure is sh~wn at 23 in Fig. 1 exiting half-cell forming
1 5 apparatus 2~.
~ In accordance with the present invention, there is
t provided an apparatus for applying at least, one adhiesive
component to the honeycomb half-cell structure. The
apparatus ~or applying the adhesive component is shown at 24
lo in Fig. 1. Apparatus 24 is part of over-all system 10, and
will be described in greater detail below. An adhesive-
coated half-c211 structure is shown exiting the adhesive
applying apparatus at 25 in Fig. 1.
In accordance with the present invention, there is
15 pro~vided an apparatus for cutting the continuous supply of
honeycomb half-cell ~tructure into a plurality of sheets.
The-cutting apparatus of the present invention is shown
generally at 26 in Fig. 1. Cutting apparatus 26 is a part
of overall system lO,-and will b described in greater
20 detail below.
In accordance with the present inYention, there is
provided an apparatus for stacking a plurality of sheets of
half-cell structure to make a hexagonal-cell honeycomb core.
The apparatus is shown at 29 in Fig. 1. Apparatus 29 is
25 part of over-all system 10, and will also be described below
in greater detail. Apparatus 29 includes a stacker arm 31
for transferring the sheets to *he top of a stack of sheets
of half-cell structure and a itack holder 32 for supporting
the ~tack of sheets. Stacking apparatus 29 also includes an
30 air handling system 33 for-providing conditioned air for
heating the stack of sheets in the stack holder to cure an
adhesive system applied thereto and a heated enclosure 34.
The sheets are pressed together while they are hPated,
thereby forming a hexagonal-cell honeycomb core 30. Core 30
35 is shown sitting in ~tack holder 32 in Fig. 1.
~s~
, WO93/10970 PCT/US92/10~91
`" i ,~, J ,~ f.~
Fig. 2 is an exploded view of a corner section of
the assembled honeycomb core, where the assembled she~-ts are
shown spaced apart sligh~ly for the purpose of defining the
half-cell structure surfaces and how ~hey come together to
make up ~he~core. As shown in Fig. 2, each sheet of half-
cell s~ructure in the assembled core, such as sheet 39,
comprises a plurality of convex surfaces, or-1peaks, ~2 on
one side of the sheet and a plurality of concave surfaces,
or valleys, 44 on the same one side of the sheet. The other
side of sheet 39 also comprises a plurality of convex
surfaces, or peaks, 42' on the other ~ de of the sheet an~ a
plurality of conca~e surfaces, or vall~ys, 44', on the same
other side of the sheet~ For reference purposes in Fig 2,
the one side of the sheet of half-cell structure is facing
up and the other side of the same sheet is ~acing down.
Peaks 42 on the one side are opposite valleys 44' on the
other side, and valleys 44 on the one side are opposite
peaks 42' o~ the other side. A diagonc surface 46 is
formed between each cons -~tive peak ana vall~y on the one
side of the sheet, and 2 ~gonal surface 46' is formed
between each consecutive ~ ak and valley on the other side
of the sheet. When a first sheet 39 of half-cell structure
is stacked on top of a second she~t 41 of half-cell
structure to form a core 30, pea~s 42' on the other side of
the first sheet contact peaks 42 " on the one top side of
the second sheet.
. Referring again to Fig. 1, system 10 also includes
a central control system 35 and ~istributed control centers
36, 37 and 38 which coordinate the handling of the web of
material or hal~-cell structure and temperature monitoring
and motion control in half-cell forming apparatus 20, in
adhesive applying apparatus 24 and in stacking apparatus 29,
respectively. Various safety interlocks and emergenc-~ shut-
down procedures are monitored and implemen~ed by central
control system 35 and by a plurality of distributed control
syste- 36, 37 an~ 38. Distributed control system 36
11
, W093/l0970 ~ PCT/USg2/10191
controls the ispeed and various methods of heating the half--
cell fo~ming apparatus. It also provides process
temperature tension and speed monitoring for this apparatus.
~, Distributed control system 37 controls roll speed and resin
5 temperature~in adhesive applying apparatus 24. Distributed
control system 38 controls the operation of cutting
apparatus 26, including the motion of conve~r 28, and the
operation of stacking apparatus 29, including th~ motion of
stacker arm 31 and stack holder 32. It also controls the
10 temperature in the stack holder~
~ Fig. 3 is a schematic view of a portion of half~
j cell fQrming apparatus ~o during the thermal cycle of the
1' apparatuis when the material of the web is deformed and set.
i The half-cell forming apparatus of the present invention
-. 15 comprises means for positioning a length of the web while
maintaining the tension thereo~. The positioning means
includes an upper loop 102 and a lower loop 104 a~ shown in
Fig. 3. Upper loop 102 comprises a plurality of upper bars
60a and ~9b attached to a pair of chains, and lower loop 104
20 comprises a plurality of lower bars 62a and 62b, attached to
another pair of chains. The bars of each loop include at
'j lea~t one surface for contacting the web. Upper loop 102
and lower loop 104 are disposed in a housing 128. A web 98
enters housing 128 at the left in Figs. 1 and 3 and is
25 carried between the bars of the upper and lower loops as
j they travel in parallel alignment between an entry nip 106
¦ and an exit nip 108. The web exits as ~ormed half-cell
3 structure 23.
The half-cell structure in forming apparatus 20 is
30 shown more particularly in Fig. 4. The web of material is
placed between meshed bars 60a, 62a and bends back and forth
over the corners, such as those shown at 68 and 70 in Fig.
~, 4, of the bars. The width.o~ the upper and lower bars, as
illustrated by reference numerals 67 and 69, respectively,
35 d~termines the width of the peaks and valleys of the half-
,~ cell structure. The creased form of the-half-cell structure
l 12
W093/10970 PCT/US92/l0191
!1'~'3~
is locked in when it sxits the half-cell forming apparatus
at exit nip 108 as s~own in Fig. 3, so that the pitch of the
half-cell structure is similar to the pitch of the half-cell
forming apparatus. The bars of the half-cell forming
apparatus o~ ~he present invention are not to be degraded by
the high t~mperatures achieved during ~he operatiQn o~ the
apparatus. ~lso, the bars have a surface f~nlsh ~hat does
not stick to the web. A bar material that has been found to
work well with a variety of webs is a nickel-coated carbon
steel.
As shown in Figs. 5A and 5B, the bars are
connected to each other and supported on each end by a pair
of upper roller chains 70a and 70b and a pair of lower
roller chains 72a and 72b. Upper roller chains 70a and 70b
are supported by a plurality of driven sprockets 74a and 74b
disposed on a shaft 76 and a plurality cf upper idler
sprocket~ 78a and 78b disposed on an upper entrance shaft
800 Lower roller chains 72a and 72b a-e supported by a
plurality of dri~en sprockeks 82a and 82b disposed on a
shaft 84 and by a plur~lity of lower idler sprockets 86a,
86b disposed on a lower entrance sha~t 88. Driven sprockets
74a and 82a and idler sprockets 78a and 86a are also shown
in Fi~. 3. Upper idler sprockets 78a, 78b and lower idler
sprockets 86a, 86b are all surrounded by an enclosure 110,
although in Fig. 3 only idler spro~kets 7~a and 86a are
shown surrounded by the enclosure. Shafts 76 and 84 are
driven by engagement with a driving chain 90 as shown in
Fig. 5B that is entrained oYer an uppPr sprocket 92, a lower
sprocket 94 and a motor-dri~en sprocket 96. Upper and lower
sprockets 92 and 94, respectively, upper chains 70a and 70b
and lower chains 72a and 72b, and upper bars 60a, 60b and
lower bars 62a, 62b must be carefully aligned by measuring
the bar locations around shafts 76 and 84 for accurate
positioning of the bars to make accurately formed half-cell
structure. Upper idler sprockets 7Ba, 78b and lswer idler
sprockeks 86a, 86b are made as small as practical to bring
13
WO93/1097~ PCT/US92/1~l9l
attached bars into-mesh over a small, sharp radius so
the wab is engaged between cooperating bars before it
contacts and is restrained by succeeding bars.
The half-cell forming apparatus of the present
invention c~mprises means for pre-heating the positioning
means to at least th~ deformation temperature of the web
before the positioning means is placed in c0ntact with the
j web. Preferably, the pre--heating means comprises an
' induction coil 112 disposed adjacent the web-contacting
: lo surface of the bars of upper loop 102 for heating upper bars
60a, 60b ~o a temperature above the web deformation q
temperature just before they enter enclosure 110. The pre-
hea ing means also preferably includes an induction coil 118
disposed adjacent the web-contacting surface of the bars of
lower loop 104 for heating lower bars 62a, 62b. Upper
roll r chains 70a, 70b, which support bars 60a, 60b and
J~ lower roller chains 72a, 72b, which support bars 62a, 62b,
remain outside coils 112, 118, respectively, and are not
heated by the coils. Preferably, induction coils 112, 118
heat the entire web-contacting surface of the bars of each
lsop. The pre-heating means may also comprise any heating
source, including, but not limited to, a radiant heater, a
convection heater, or an electrical resistance heater.
Upper bars 60a, 60b are supported relative to coil 112 by a
slide 116, and lower bars 62a, 62b are supported relative to
~ coil 118 by a slide 122. The pre-heating means also
¦ inclu~es a plurality of forced air blowers 103, 105 as shown
j in Fig. 3 disposed on the outer surface of each loop, which
maintain the web deformation tempPrature on the bars
3Q established by induction coils 112 and llB.
The half-cell forming apparatus o~ the present
invention also comprises means for maintaining the tension
' on the positioning means and for cooling the positioning
means to the stabilization temperature of the web while
holding the web thereon. The tension maintaining and
cooling means comprises an upper back-up plate 124 and a
14
WO93/10970 PCT/US92/10191
lower back-up plate 126 as shown in Figs. 3 and 5B disposed
~, on the respective inner surfaces of the bars of upper and
lower loops ~02, 104, respectively. In addition, a
plurality of blowers 121 and 123 as sho~n in Fig. 3 is
,~ 5 provided wh~ch circulate cooling air through the bacX-~p
plates and around bars 60a, 60b and 62a, 62b and web 98. As
~hown in Figs. 3 and 4, web 98 extends bet~een upper back-up
plate 124 and lower back-up plate 126. It is important to
~ ensure that ~he web is held tightly against the corners of
-¦ 10 the bars during cooling, thereby maintaining tension in the
¦ web, so that sharp, accurate bends will be made in the wPb
to form the half-cell structure. Back-up plates 124, 126,
in addition to cooling the bars, maintain the tension on the
i web.
As shown in Figs. ~A and 5B, upper back-up plate
124 is pivotably held at the upstream end on a plurality of
threaded rods 404a, 404b by a nut 418 on each rod an~ by a
~, plurality of springs 420a, 420b held under a plate 422.
i Springs 420a and 420b d~ not permit vertical translation of
20 back-up plate 124 along rods 404a and 404b, respectively,
but they do permit rocking and thereby acts as a pivot for
one end of upper back-up plate 124. The other end of upper
back-up plate 124 is pressed toward l~wer back-up plate 126
by a plurality of springs 424a, only one of which is shown
~, 25 in Fig. 5B. ~he back surface of upper bars 60a and 60b
¦ slides on a surface 426 as shown in Fig. 4 at the two
later~l edges of upper back-up plate 124. Also, as shown in
Fig. 5B, lower back-up plate 126 is fixedly supported at one
and on threaded rods 404a and-404b (Fig. 5A) by a plurality
30 of nuts 406, 408 engaging the end of back-up plate 126 and
' at the other end by a plurality of threaded rods, such as
,~ 410a, and by a plurality of nuts-412 and 414. The bacX
,~ surface of lower bars 62a and 62b slides on a surface 416 as
shown in Fig. 4 at the two lateral edges Qf lower back-up
35 plate 126.
WO93/10970 ~ PCT/U592/10191
The back-up plates comprise a plurality of
channels for providing cooling fluid to the back surfaces
thereof. A description of the cha~nels will be made with
reference to Figs. 4 and 5B. The channels include a fluid
port 428a and 428b, an adjustable slot 430a and 430b and a
groove 432a and 432b, formed in upper back-up pla e 124 and
lower back-up plate 126, respectively. The'channels also
include a plurality of exit ports 434a and 436a as shown in
Fig. 5B formed in upper back-up plate 124 and exit ports
434b and 436b formed in lower back-up plate 126. Fluid
ports 42Ba and ~28b are in fluid communication with groove
432a and 432b, respectiv~ly, via adjustable slot 430a and
430b, respectively. Exit ports 434a and 434b and 436a and
436b are disposed in fluid communication with the ends of
grooves 432a and 432b, respectively. Cooling fluid flows
through port 428a, into groove 432a via slot 430a and out
through exit ports 43~a and 436a to cool the back surfaces
of upper bars 60a, 60b as shown in Fig. 4 which contact
upper back-up plate 124. SLmilarly, cooling fluid flow
through port 428b, into groove 432b via slot 430b and out
through exit ports 434b and 436b to cool the back surfaces
of lower bars 62a, 62b which contact lowsr back-up plate
126.
When pre-heating the web, it has been found that
it is not sufficient to snly heat the material of the web
and bring it into contact with a lower temperature surface,
such as that of the bars, to lock in the creases. The
~hermal inertisl o~ a thin web is ~ry low, SQ a heated web
would be quenched too rapidly by a cooler surface before a
sharp crease would form. I~ the web does not reach the
deformation temperature upon contact with the bars, the
bending stress applied may be insufficient to sharply crease
the web. Later h~ating to the deformation temperature would
then produce slack portisns of web on the bars, and an
inaccurate hal~-cell structure would result. In order to
prevent this, it is necessary to heat the bars to at least
16
~ WO g3/10970 PZ~r/VS92/10191
Z~
the deformation temperature of the web before the web is
placed in contact with t~e bars. It is also necessary for
the material of the web to immediately conform to sharp
corners, such as those shown at 68 and 70 in Fig. 4, of the
~J 5 half-cell fbrming apparatus bars upon contZ~Z_t and be held in
the creaZ~--ed fonm at the web deformZlation tem~erature fox a
brief moment before lowering the temperatuffe to the
stabilization temperature of the web. Therefore, the bars
of the half-cell forming apparatus of the present inventîon
lo must be cycled in temperature to the web stabilization
temperature while t~e web is held thereon tG set the creases
and then back to the web deformation temperature so that it
~Z is ready for the next section of web. In addition, the web
Z may be pre-heated to essent ly the web deformation
15 temperature when contacting ~ bars a L entry nip 106. For
s7Z very -lin wabs with low the~ . inerti~, pre-heating the web
may not be necessary, as the ~b will rapidly reach the
deformZation tZ~mllperature just ~y contac;ing the bars.
Z Heavier webs may reZ~uire pre-heating.
¦ 20 The bars and the web are held at the deformation
Z temperature for the time they remain in enclosure 110. The
~; bars and the wPb are lowered in temperature to the
stabilization temperature of the material of the web after
lea~ing enclosure 110. Housing 128 is kept at a temperature
¦ 25 generally near the web stabilization temperatureO The web
I should not be released from the bars until it has reached
~he stabil,zation temperature, or the bent form of the half-
cell structure will not be accurately ret^-ned. FoZr an
Z aramid paper, such as a paper made from y(m-phenylene
30 isophthalamide), the deformation tempera~re is a
temperature near or above the glass transition temperature
and below a temperature that will thermal' degrade or
significantly discolor the paper. The st ization
temperature is a temperature significant: ~elow the
35 deformation temper~ture, so that de~orma~ on of the half-
cell structure wili no longer occur, but not so far below
17
W~93/10~70 ~ PCT/US9~/10191
that reheating the bars is difficult. The stabilization
temperature 'llocks inl', or sets, the form of the bars in the
web.
In addition, it is important that the web is
placed on bars 60a, 60b, 62a, 62b while under tension, and
that tension is maintained on the web while it is held on
the bars. The entrance tension on web 98 in Fig. 3 as it
enters the half-cell forming apparatus will not be
transmitted through the web after it has passed over several
bar~, 60a, 60b, 62a and 62b, as shown in Fig. 4, because of
friction. For some webs, web tension develops as the web~
icontracts during cooling, but for other webs, the thermal
expansion coefficient is low, so no appreciable contraction
occurs during cooling. For such webs, special methods of
tensioning are achieved by back-up plates 124 and 126 as
described above. The back-up plates ensure sharp corners,
such as those shown at 68 and 70 in Fig. 4, are maintained
in the half-cell structure, in spite of tolerance variations
in chains 70a, 70b, 72a, 72b, in bars 60a, 60b, 62a, ~2b and
in upper back~up plate 124 and lower back-up plate 126a
Hal~-cell structure forming apparatus 20 is set to
run at a spead to allow sufficient time for heating the bars
;of the apparatus and the web to the deformation temperature
of the web and for cooling the bars and the web to the
stabilizatisn temperature of the web. The web enters half-
cell structure forming apparatus 20 at entry nip 106 as
shown in Fig. 3 as a flat web o material under tension and
exits as a supply of half-cell structure under no tension,
except tha~ imposed by the fre2 weight of the exiting half-
130 cell structure~ The half-cell structure hangs under its own
weight as shown in Fig. 1 when it comes out of the half-cell
forming apparatus.
¦In accordance with the present invention, there is
provided a process of making a honeycomb half-cell ~tructure
from a web of material. The process comprises the steps of
pre-heating a plurali y of bars, such as bars 60a, 60b, 62a
18
~, W093/10970 PCr/USg2/10~91
~ ~ 1 2 ~
and ~b to at least the deformation tE~perature of the web
and contacting the outer surfaces of the bars with the web.
i~ The wab and the bars are then cooled to the stabilization
temperature of the web while holding the web on the bars.
The web is ~h n removed from the bars. The pre-heating st~p
3~ includes heating the wab-~ontacting surfaces of the bars.
In addition, the pre-heating step includes'induction heating
the bars. Preferably, the entire web-contacting surfaces of
the bars are induction heated. Additionally, the web may be
pre-heated before it is placed on ~he bars. The web is
maintained under ten-~ion -~hile it is placed on the bars, ns
well as while it is held on the bars.
In accordance with the present invention, there is
! provided a process for making a hexagonal-cell honeycomb
i 15 core from a honeycomb half-cell structure. The process
comprises the steps of applying a first adhesiv~ component
to a first group of peaks, apply~g a second adhesive
compone~t to a second group of p ~s and stacking the half-
cell structure so that the first adAesive component on the
first group of peaks comes into contact with the second
adhesive component on the second group of peaks, thereby
mixing the components to bond the half-cell structure
together and form the honeycomb core. This process is
illustrated with reference to Fig. 6. Fig. 6 is an
enlarged, perspective view of a portion of half-cell
stru~ture 25 which has been coated with at least one
adhesive. As noted above with resp~ct to the description of
Fig. 2, the peaks on one side of ~he half-cell ~tructure are
opposite valleys on the other side of the gtructure, and th~
valleys on the one side of the structure are opposite peaks
on the other side o~ the structure. The step of applying
the fir t adhesive component comprises applying the first
adhe i~e component to the peaks on ~he one side of the
structure, such as those shown at 42 in Fig. 6. The step of
applying the second adhesive component comprises applying
the second adhesi~e component to the peaks on the other side
19
,",. , , . ~
WO93/10~70 ~. 2 ~ -~ '3 '`~ P~T/US92~10191
of the structure, such as those shown at 42' in Fig. 6. In
the present invention, ~he two adhesive components are post-
mixed after the half-cell tructure is stacked, thereby
allowing the two adhesive components of ~he adhesi~e system
of the pres~nt invention to come into contact and cure to
produce a strong bond~ ~he adhe~ive components remain
sticky during ~he application thereof and durlng stacking to
preserve the alignment of the shs~ts while the adhesive
i components cure.
j 10 The step of applying the first adhesive component
~ ~omprises applying a cyanate ester and an epoxy to the fi~st
3 group of peaks. A preferred first adhesive c~mponent is a
combination of a cyanate ester s~1ch as Arocy B-30,
, commercially available from Hi-Tek Polymers, a subsidiary of
i 15 Rhone Poulenc, of Louisville, Kentucky, and an epoxy, such
~ as Epoxy Epon 826, commercially available from Shell
d, Chemical Company of Houston, Texas. Any of the following is
also suitable for the first adhesive component: epoxies,
polyesters, polyimidesj phenolics, polyureas~ polyurethanes
and bi3~maleimides. ~ny of the corr~sponding curins agents
or ca alysts for the above list are suîtable for the second
adhesive component. A purpo3~e of the epoxy in the first
adhesive component is to reduce the viscosity of the cyanate
ester. It also accelerates the cure of the adhesive system
when hsat is applied. The first component can cure by
itself over a long time (several hours or days) or quickly
(se~eral seconds) when a catalyst is used and heat is
applied. The step of applying ~he second adhesiYe component
¦ comprises applying ~n epoxy an~ a catalyst to the second
group of peaks. A preferre~ secsnd adhesiYe component is a
combination o~ the epoxy of the first adhesive component and
a catalyst, such as zinc octoate soap. A purpose of the
epoxy in the second adhesive co~ponent is to increase the
viscosity of the catalyst. Preferably, the epoxy is the
same epoxy as thaS used in the irst adhesive component;
however, the epoxy may be a different epoxy.
'
W093/1~970 ~ 3 ~ ~ 9 PCF/US92/lO~9l
In accordanc~ with the present invention, there is
provided a hexagonal-cell honeycomb core made by the process
of applying the fir~t adhesive component to the first group
of peaks and applying the second adhesive component to the
second group of pea~s and stacking the structure so that the
first adhesive component on the first group of peaks comes
into contac~ with ~he second adh~sive compo~ent on the
second ~roup of peaks. In addition, there is provided a
hexagsnal-cell honeycomb core made by the process of
applying a cyanate ester and an epoxy to the first group of
peaks and applying the epoxy and a catalyst to the second~
group of peaks. Also, there is proYided a hexagonal-cell
honeycomb core made by the process of applying the first
adhesive component to the peaks on one side of the structure
and applying the second adhesive component to the peaks on
the other side of the structure.
In accordance with the present invention, there is
provided a process for making a hexagonal-cell honeycomb
core from a honeycomb half-cell structure. The proc ss
co~prises the ster?s of applying a sticky adhesive to the
¦ peaks of the hal~-celi structure and stacking the half-cell
I structure while the adhesive remains sticky. The viscosity
of the sticky a~hesive of the pr~sent invention is at least
¦ 500 centipoise (cp) measured at the temperature at which the
2~ two sides of the half-cell structura are joined together.
The application step comprises ap~~ying a first adhesive
componen~ 48 to a first group of peaks and applying a second
adhesive compe~ent 50 ~o a second ~roup of peaks. The first
group of peaks is disposed on one side of the half-cell
structure, such as the upper side of the hal~-cell
structure, and inc~udes the peaks coated with first adhesive
component 48 as shown in Fig. 6. The second group of peaks
is disposed on the other side of the half-cell structure,
such as the lower side of the half-cell structure, and
includes the peaks coated with the second adhesive component
50 a~ shown in Fig. 6. The step of applying the first
21
: ` :
WO93/10970 . PCT/US92/10191
~ 1 ~ 3 ~ t ~ -
adhesive comprises applying a cyana~e ester and an epoxy to
the first group of peaks on one side of the structure, and
the step of applying the s~cond adhesiv~ comprises applying
an epoxy, which is preferably the epoxy of the first
adhesive bu~ which may be ~ different epoxy, and a catalyst
to the second group of peaks on the other side of the
structure. The half-cell structure is cut ~nto a plurality
of sheets while the adhesive on the peaXs remains sticky.
The half-cell structure is cut across the diagonal surface.
The sheet~ of half-cell structure are thsn stackad. A
hexagonal half-cell honeycomb core such as core shown at 30
in Fig. 2 is thus produced.
The advantages offered by the adhesive system of
the present invention include the following. The components
do not set rapidly by themselves, so that there is adequate
time after ~pplying the adhesive to feed, cut, position and
stack the sheets of half-cell structure. Also, each
component ha~ a long pot life, i.e., it does not degrade
during the time it is held at an ele~ated temperature in the
1 20 adhesive-applying apparatus for several hours during
I operation. In addition, the components are fluid enough
I ti.e., have a low viscosity~ to spread in a ~hin layer, but
are viscous enough not to run or drip. Furthermore, the
components are sticky at the stacking temperature so the
accurate position achieved during stacking is immediately
retained again~t small disturbing ~orces until the adhesive
components gel to form a strong ~ond. Also, the compon~nts
form a strong bond quickly (i.e., they have a fast gel time
of about one minute or less) when subjected to elevated
temperatures. Each wet component has good adhesion with the
honeycomb half-cell structure, which makes a thin uniform
coating which is easy to apply. Also, the set adhesive
I adheres well to the half-cell structure to create a strong
bond. In addition, the cured adhesive has high temperature
resistance ~i.e., a high glass transition temperature) of
about 177 degrees C.
22
W093~10970 P~T/U~92/10191
' 3~
Moreover, the adhesive system of the present
invention is solvent-less. In systems using solvents, as
the solvents evaporate between ~Ae two half-cell sheets at
the bond, bubbles may form that decrease bond strength.
Also, ~he e~aporated sol~ents may pose an environmental
hazard that must be contained and scrubbad. Th adhecive
system of the present invention ~hus has t~e adYan age over
other adhesives which must include sol~ents to achieYe low
viscosity.
In additiDn, the adh sive system of the present
invention is in a f~owab}e~ liquid form as the next-~eet.of
half-cell structure is plac~d on the top of the co~e~- This
ensures that the ~dhesive components will mix properly and
~, will flow into irregularities in the half-cell structure
peaks and form a large area for bonding where the peaks are
pressed tog~ther. A thick lay~r of low-viscosity a~hesive
wastes adh~sive, flows-into ~ndesirable parts of the
apparatus and the honeycomb core and produces a poor
performance-to-weight product. A high-viscosity adhesive
does not fill irregulariti s and mix adeguately for a large
area bond. If an alternate adhesive were used that is
~¦ "dry", when the top half-cell sheet is placed on the
~, honeycomb core, the adhesive may become sufficien~ly-~luid
to form a bond when heated, but this reguires time during
¦ 25 which mis-registration may occur. It would also require a
¦ higher pressure to produce a good contact bond, which
¦ pres~ure may excessively deform the honeycomb core.
An alternate embodiment of the present invention
¦ is illustrated in Fi~s. 7A and 7B. This alternate
3 30 embodiment includes the step of cutting the half-cell
il stxucture in~o a plurality o~ sheets. According to this
¦ alternate embodiment, th~ step o~ applying a ~irst adhesive
component includes applying a ~irst adhesivs component 48'
~ to the peaks on each side of a first portion of the half-
-~ 35 ell structure. The step of applying a ~econd ~dhesive
component includes applying a second adhesive component 50'
23
.~
WO93/10970 PCT/US9~ 191
to the peaks on each side of a second portion of the half-
cell structure. The first and s~cond adhesive components
may be, but are not limited to the first and second adhesive
components as described above. The stacking s~ep as shown
in Fig. 7B includes cutting a plurality of sheets from each
portion and alternately placing a sheet from~the first
portion on a sheet fr~m the se~ond portion so that the peaks
of the ~heets of the first and second portions come into
contact, thereby mixing the first and second adhesive
components together. It should ~e noted that the method
according to this embodiment of the present invention may4be
practiced when the half-cell structure is a continuous
supply or is cut into sheets. Also in accordance with the
present invention, there is provided a hexagonal-cPll
honey~omb core made by the process described with respect to
Figs. 7A and 7B.
Another alternate embodiment of the presen~
invention i5 illustrated in Figs. 8A and 8B. In this
al~ernate emb~diment, the step of applying a first adhesive
component includes applying a first adhesive component 48 "
to the peaks of one side of a first portion of the half-cell
structure and to the peaks of the other side of a second
portion of the half-cell structure, where the first and
second portions are separated by a fold line. Also, the
~tep of applying a second adhesi~e component includes
applying a second adhesive component 50 " to the peaks of
the other side of the first portion and to the one side of
khe second portion. As in the embodiment of Figs. 7A and
7B, the first and second adhesiv~ components may be, but are
3 0 not limited to, the ~irst and second adhesive aomponents as
de~cribed above . The stacking step includes folding the
half-cell structure so that the first and second portions
face each other and the first adhesi~e component on the
peaks o~ the first and second portions is in contact with
the econd adhesive component on the peaks of the first and
second portions. This stacking step is shown in Fig. 8B.
24
W093/10970 - PCT/US92/10191
'~? ~ t~ ;3 ~
Also in accordance with the present inventicn, there is
provided a hexagonal-cell ho~-~ycomb core made by ~he process
described with respec~ to Figs. 8A and 8B.
The above-discussed processes for applying at
least one a~hesive component to half-cell structure may b~
implemented with adhesive-applying apparatus 24 as shown
generally in Fig. l. ~ig. gA is an enlarge~, perspective
view showing adhesive-applying apparatus 2~ in greater
detail. The apparatus comprises at least one gravure roll
for coating the half-cell structure with at least one
I adhesive component. A gravure roll is shown at 138 in Fig.
`~ 9A, The at least one gravure roll includes first gravure
roll 138 as noted above for coating one side of the half-
cell structure with the first adhesive component and a
second gravure roll 144 for coating the other side of the
half-cell structure with the second adhesive component.
First gravure roll 138 is disposed in a first adhesive bath
43 which contains the first adhesive component. Second
~ gravure roll 144 is disposed in a second adhesive bath 45
i 20 which contains the second adhesive component. First and
second gravure rolls 138 and 144 ~ach has a plurality of
pits 14l and 143, respectively, formed therein. ~he first
adhesive component is held in pits 141 on first gravure roll
138, and the second adhesive component is held in pits 143
on second gravure roll 144. Pref~rably, ~he first and
s~cond adhesive compon~nts are applied to the peaks of each
side of tne half-cell structure.
The apparatus also comprises means for positioning
the hal~-cell structure against the gravure roll.
Preferably, the positioning means is resilient. Also
preferably, the positioning means comprises at least one
back-up roll. A back-up rsll is shown at 130 in Fig. gA.
Back-up roll 130 includes a pl -ality of bars 137 on the
surface thereof for supporting :he half-cell structure. A
space 127 is formed between each consecutive bar 137. In
addition, the posikioning means may comprise any other
2~
WO 93/10970 PCI`/US~2/10191
~ 1 3 ~ 9 ~
device for positioning half-cell structure against a gravure
roll, including, but not limited to, a transfer head or a
b~lt with teeth on it. The positioning msans may also
comprise a second back-up roll 132 for positioning the half-
cell structure against the second gravure roll. Back-up
roll 132 includes a plurality of bars 13g on the surface
thereof for supporting the half-cell struct~re against
second gravure roll 1~4. A space 129 is formed between each
consecutive second bar 139. Preferably, first and second
lo back-up rolls 130 and 132 are resilient; specifically, bars
137 and 139 are resilient. The depth of the spaces of the
first and second back-up rolls is greater than the height of
peaks 42 on the half-cell structure. Back-up rolls 130 and
132 contact thP half-cell structure at a contact surface 120
and are relie~ed around spaces 1~9 as ~hown in Fig. 9B. The
I peaks on one side of the half-cell structure face away from
¦ bars 137 of first back-up roll 130.
i Referring to Fig. 9B, this arrangement of
contacting the half-cell structure at Yalleys 44 and not
contacting it at peaks 42 is important to ensure uni~orm
support at surface 120 and therefore a uniform coating of
adhesive. Space 129 must provide clearance so second back-
up roll 132 does not contact adhesive coating 48 on peak 42.
Even when an adhesive coating is absent (as it is on first
¦ 25 ba~k-up roll 130), if space 129 ma~ched ~he theoretical
pro~ile of peak 42 and diagonal surfaces 46, the actual
height o~ the peak would vary from the theoretical, so a
perf~ct match would not always occur. If peak 4~ were
higher than the "matching" depth o~ space 129, valley 44
would not fully engage contact surface 120, and uniform
application o~ adhesive to peak 42' would not occur.
The peaks on the half-cell structure face away
from the bars of each respective back-up roll, and the peaks
con~act each respective first and second gravure roll so
that ~he ~irst adhesi~e component contacts the peaks on the
one side and the second adhesive component contacts the
'
~ 26
,
~7.15~ . !
~VO93/10970 ~ 9 PCT/US92/10191
peaks on the other side to apply the fi~st and second
adhesive componen~s to the half-cell structure.
Specifically, valleys 44 on the one sid~ of tha half-cell
structure are placed in contact with the bars on second
back up rol~ 132; peaks 42' on the other sid~ of the half-
cell structure face away from bars 139 on se -~nd back-up
roll 132. Also, valleys 44' on the other s~e of the half-
cell structure are placed in contact with the bars on first
back-up roll 130; peaks 42 on the other side of the half-
cell structure face away from bars 137 on first back-up roll
130. Accordingly, the first adhesive component contacts t~e
peaks on the one side and the second adhesive component
contacts the peaks on the other side of the half-cell
structure to apply the first and second adhesive components
to the half-cell structure.
First and second ack-up rolls 130 and 132,
respectively, are driven together at the same speed through
suitable gearing by a motor 452. A motor 454 drives first
gravure roll 138, and a motor 456 drives second gravure roll
144, so that the first and second gravure rolls are driven
separately. The gravure rolls are preferably driven at the
~ame speed as the back-up rolls. ~irst gravure roll ~38,
first adhesive bath 43 and motor 454 are attached to a
carriage 455 for reciprocation by a cylinder 457 in the
directi4n of arrow 458 to press toward and away from back-up
roll 130. Second gravure roll 144, second adhesive bath 45
and motor 456 are similarly disposed for movem~nt in the
direction of arrow 460 to press toward and away from back-up
roll 132. When the gra w re rolls are retracted from the
back-up rolls, they can be independently driven by their
respective motors 454 and 456 to agitate their respective
adhesive baths.
A dif~erential pressurP system is shown at 436 in
Fig. 9A and includes a vacuum source 437 and a pressure
source 462. A-vacuum is applied at each of spaces 127 and
129 through at l~ast one vacuum hole 131, as shown in Fig.
' WO93/10970 y 3 ~ ~ X ~ 9 PCT/US92/10191
,
! ~B only, on back-up roll 132 to hold the half-cell structure~, agai~st or separate it ~rom the ~irst and second back-up
~ rolls. By providing ~he vacuum holes on the non-contacting
! portion of the back-up rolls, the peaks of the half-cell
structure a~e not deformed on contact surface 120, as they
might be if the vacuum holes were located there. This is
important to achieve good contact between t~e entire area of
the peaks and the adhesive on the pitted surface of the
first and second gravure rolls. The back-up rolls are in
fluid communication with vacuum source 436 over about 270
degrees.of rotation and with pressure source 462 over abo~t
90 degrees of rotation, as determined by a pair of non~
~, rotating partitions 134 and 136 formed within the back-up
`¦ rolls. The elevated pressure ensures the half-cell
structure is positively separated from the back-up rolls
when the vacuum is removed at the partitions.
As shown in Fig. 9A, the half-cell structure is
held ~ightly on back-up rolis 130 and 132 and is ~rought
into contact with gravure rolls 138 and 144, respectively.
Gra w re roll 138 has a peripheral surface 140 and is
disposed in contact with bath 43 of the first component of
the two-part adhesive. Gravure roll 144 has a peripheral
surface 145 and is disposed in contact with bath 45 of the
second component of the two-part adhesive system.
Peripheral surface 140 of gravure roll 138 is coatad with a
~ilm of the first component, and peripheral surface 145 of
gravure roll 144 is coated with a film of the second
component. A doctor blade 142 wipes peripheral surface 140
of gravure roll 138 clean, leaving the adhesive component
~ 30 only in pits on the urface of gra~ure roll 138. A doctor
i blade 1~7 similarly wipes peripheral surface 145 of gravure
roll 144. This arrangement accurately controls the adhesive
thickness, and thus contro}s the quantity of the adhesive
applied to the half-cell structure. The thickness of the
layers of the first adhesive component and the second
adhesive component, respectively, applied by the adhesive-
28
~r~ , . . . . .
WO93/10970 P~T/US92/10191
9 !~
applying apparatus of the present invention may be the same,but do not necessarily have to be so. The discre~e spots of
the adhesive components transf~rred to the half-~ell
structure by the adhesive-applying appar~tus of the present
invention c~alesce into a continuous film, or areas of film,
as the half-cell structure leaves gravure rolls 138 and 144.
As noted above~ back-up rolls 130~and 132 are
preferably made of a resilient material, such as rubber.
Gravure rolls 138 and 144 are formed from a non-elastic
metal, Thus, resilient back up rolls 130 and 132 can be
brvught into pressing contact with non-resilient gravure
roll 138 and 144, respectively, an~ intimate contact
between the half-cell structure and ~ch gravure roll is
assured~ This arrangement controls the uniformity of the
application of the adhesive.
As the half-cell structure is pressed against the
surfaces of gravure roll 138, it contacts pools of the first
adhesive c~mponent which collect in the pits of the roll,
and the component is transferred to the peaks of the half-
cell structure. As the half-cell structura leav s first
back-up roll 130, it is inverted so that the top of the
half-cell structure is facing second back-up roll 132. This
allows the peaks on the other side of the half cell
structure to come into contact wi~h the second adhesive
compon~nt on the ~urface of gravure roll 144. The adhesive-
coated half-cell structure i~ released from second back-up
roll l32 and is guided into ~ unsupported loop, shown near
the bottom of Fig. 9A. The continuous half-cell structure
leaYing adhesive applying apparatus 2~ has sticky adhesi~e
applied to the top and bottom peaks, and therefore these
surfaces cannot be touched. The half-cell s~ructure is
released from ~acuum source 437 and is guided and supported
with a flow sf air from a slot jet 438. The half-cell
structure falls into a free loop as shown near the bottom of
Fig. 9A. A senssr 440 detects the presence or absence of
29
W~ g3J10970 Pcr/uss2~l0lsl
~ ; 2 .~ ~ 3 ~ ~ ~
the loop. Sensor 440 is connected to distributed control
system 38 as shown in Fig. 1.
In accordance with the present invention, there is
provided a process of applying at least one adhesive
5 component to a continuous supply of honeycomb half-cell
structure. The process comprises the step of directing the
half-cell structure to at least one gravure'roll, such as
first gravure roll 138 and second gravure roll 1~4. The
process also comprises the step of positioning the half-cell
10 structure against the gravure roll.
The process of the present invention further
includes the steps of ~irecting the half-cell structure
through a wrap around a first back-up roll in a first
direction and directing the half-cell structure through a
15 wrap around a second back-up roll in a second direction.
Preferably, the half-cell structure is directed through at
least a 90 degree wrap in the first direction and through at
least a 90 degree wrap in the second direction.
Z The positisning step of the present invention
20 includes the sub-step of placing the valleys on one side of
the half-cell structure in contact with a plurality of bars
I formed on the second back-up roll, where the peaks on the
! other side of the structure face away from the bars on the
Z second back-up roll. The placing st~p inaludes placing the
25 peaks on the one sid~ of the structure in a space formed
between the bars of the second bac~-up roll. The
~ positioning step also includes the sub-step of placing the
j vall~ys of the other side of the structuxe in contact with a
plurality of bars formed on the first back-up roll, where
30 ~he peaks on the one side of the structure face away from
the bars on the first back-up roll. The placing step
includes placing the peaXs on the other side of the
structure in a space ~ormed between the bars of the first
back-up rsll, whers the width of the spaces of the first and
35 ~econd back-up-rolls is about the distance between adjacent
3~
~093/10970 PCT/US92/10~91
3'"' ~'3~
valleys of the half-cell structure, and the depth of the
space is greater than the height of the peaks.
The proceæs of the present invention further
` includes the step of placing a first adhesiYe component on a
`. ~ first gravure roll, such as gravure roll 138, and placing a
second adhasive component on a second gravure roll, such as
gravuxe roll 144. The first and secon- ~dh~sive components
may be, but are not limited to, the first and second
adhesive components as described a~ove. 5pecifically, the
first adhesive component is placed in a plurality of pits,
such as pits 1~1, extending below ~h~ surface of the firs~
gravure roll. The second adhesiv ..omponent is placed in a
plur~lity of p_ts, such as pits 1~3, extending below the
i surface of the second gravure ro~l. The peaks of the one
side of the structure are then pressed between the first
back~up roll and the first gravure roll, thereby contacting
the first adhesive component with the peaks on the one side.
¦ Also, the peaks on the other side of the structure are
presced betw~en the second back-up roll and the second
gravure roll, thereby contacting the second adhesive
component with the peaks on the other side to apply the
f irst ~nd second adhesive components to the half-cell
structure. The half-cell structure is held against a first
ack-up roll, such as 130, and a second back-up roll, such
i 25 dS 132, ~y a vacuum. The vacuum is applied to the spaces,
such as 1~7 and 1~9, between the bars on the first and
seco~d back-up rolls.
. As noted ab~ve, s~ em 10 comprises cutting
: apparatus 26 for cutting the supply of h2~~-cell structure
1 30 into a plurality of sheets. -The cutting -~paratus of the
-~j present invention comprises means ~or cut~.ng the honeycomb
,alf-sell structure into a plura i~ of 51 ts. Preferably
.~he cutting means compri s a bl~d~- 157 as hown in Figs. 1
and lOA - C. Blade 157 comprise~ ~ zazor blade whirh
¦ 35 coated wi~h tungsten carbide or bc_on nitride for wear
re5istance. Blad 157 is guided across the half-cell
31
J
WOg3~970 PCT/U~g2/10191
~ ~ 2.~
structure by a conv~ntional slide mechanism driYen by an air
cylinder. Alternatively, a wire cutter, a laser or a water
jet or the like could be used as the cutting means7 An
alternate cutting arrangement to that of the present
invention iS a rotary cutter consisting of a disc rotated by
an electric or air ~otor, so that a longer lasting cutting
surface is available. '~
The cutting apparatus of the present invention
also comprises means for positioning a length of the half-
cell structure. Preferably, the positioning means comprisesa conveyor ~8 as shown in general in Fig. 1 and in greate~
detail in Figs. 10 - 13 which positions a length of half-
ell structure. The positioning means could also comprise
any other mechanical, electrical, or electro-mechanical
device or mechanism which accurately positions a length of
half-cell structure and prepares it for cu~ting. The sheets
are positioned for cutting across the diagonal surface as
shown at line 150 in Fig~ 6.
Further in accordance with the present invention,
there is provided a process for cutting a honeycomb half-
cell structure into a plur~lity of she~ts. The process
comprises the steps of positioning a length of the
continuous supply of half-cell structure on a conveyor so
that the diagonal surfaces of the half-cell structure are
2S po~itio~ed adjacent a blade for cutting~ The pro~ess also
comprises the step of cutting across the diagonal surface to
~orm ~he sheets. The process further includes the step of
~tacking the sheets onto each other so that the peaks on one
æide o~ a sheet contact the peaks on the other side of an
adjacent sheet to form a honeycomb core. Accordingly, there
is also provided a hexagonal-cell honPycomb coxe, such as
that shown at 30 in Fig. 2, made by the process of cutting
the structure across th~ diagonal sur~acPs thereof to form a
plurality of sheet~ and stacking the structure by placing a
sheek with th2 peaks on one ~ide of the sheet in contact
wi~h the peaks on the other side of an adjacent sheet.
32
WO ~3~10970 ~ 1. 2 3 ~ ~ 9 PCT~US92/10191
Referring again to Fig. 9A, adhesive~coated half-
cell structure ~5 must be guided onto the top, flat portion
of conveyor 28. The half-cell structure, which s coated
with s~icky adhesive, should be prevented frsm touching any
surface. F~r this purpose, an air bar 442 and a pair of
transpar~nt side plates 444 and 446 as shown in Fig. 9A are
attach~d to a conveyor frame 304 and a guar~ 305 as shown in
Fig. 13, which in turn is mounted to conveyor frame 304.
Frame 30~ is shown in particular ~n Figs. 12 and 13 and is
the stationary part of the conveyor. Plates 444 and 446
`, guide and support the half-cell structure without contacting
the sticky adhesive on the peaks. Plates 444 and 446 are
spaced slightly further apart than the width of the half-
cell structure. Air bar 442 has a plurality of holes 448
~5 centrally located on its surface which are in ~luid
J communication with a source of pressurized air, such as an
~, air blower 449 as shown in Fig. 9A. When the loop is sensed
by sensor 440, conveyor 28 advances the half-cell structure
, a fixed length and stops to allow cutting of a sheet of the
,~5 20 half-cell structure. While the convayor is stopped, the
loop descends as the half-cell structure is advanced by
adhesive applying apparatus 24, until the loop is detected
by sensor 440, The conveyor is advanced again, or the
adhesive applying apparatus is slowed or stopped if the
25 con~eyor cannot a~vance.
The conveyor comprises a plurality of connected
platens 139 and 145 as shswn in Figs. lOA - lOC and Fig. 11
which support the half-cell structure. Platens 139 and 145
ride on a U shaped channel 302 as shown in Figs. 12 and 13
30 which is fastened to frame 304 and which has a platen
manifold 175 provided therein. A plurality of surfaces 181
and 183 are provided on channel 302 ~or supporting platens
¦ 139 and 145. Platçns 139 and 145 ~ e connected at a pivot
146 a~ shown in Figs. lOB and lOC. Platens 139 and 145
i 35 comprisç a plurality of support bars, such as.141a-141f as
~,, shown in Fig~. lOA - lOC, which have about the same pitch as
.~ 3 3
W093J1~970 PCT/~S92/10~9l
f 1~3~
bars 60a, 60b, ~2a and 62b of half-cell forming apparatus
20. A plurality of spaces, such as 143a and 143b, is formed
betwe~n each consecutive bar as shown in Figs. ~OA - lOC.
Support bars 141a-141f of the platens contact the valleys on
the other s~de, or bot~om, of the half-cell structure.
The cutting apparatus of the present invention
incorpora~es special considerations to achi~ve accurate
alignment of adjacent sheets of half-cell structure when
they are stacked on top of each-other. The n ~ er of barc
lo on each consecutive platen alternates between an odd and an
even number. In the preferred embodiment, conveyor platens
139 and ~45 are 10-1/2 pitches long from pivot to pi~ot as
shown at 133 and 135, respectively, in Fig. 10~. The
platens have differ~nt numbers of bars and spaces. For
example, platen 145 may have 10 bars and 11 spaces, such as
141a and 143b, respectively, and platen 139 may have 11 bars
and 10 spaces. The conveyor index in the direction as
designated by arrow 1 1 as shown in Fig. lOB is constrained
to be an odd number of platens to achieve the one-half pitch
increment, ~o that blade 157 alternately cuts first on one
side of a fir~t predetermined bar, such as a downstream
side, as illustrated at 147 in Fig. lOB and then on one side
of a second predetermined bar, such as an upstream side, as
illustrated at 149 in Fig. lOC. The blade remains fixed
along the conveyor, and the conveyor advances a repeatable
distance. This distance must always be equal to an integer
plus one-half o~ the pitch of the half-cell structure.
Stacker arm 31 must move back and forth laterally one-half
pitch, as between points 153 and 155 in Figs. lOB and lOC,
to pick up alternate sheets of half-cell structure.
Platens 139 and 145 are connected in an endless
chain 300 which comprises support bars 141a-141f. Platen~
139 and 145 are driven and supported by a chain idler
sprocket 33 and a chain driYe sprocket 35 as shown in Fig.
12. A shaft 306 is supported on frame 304 and holds chain
idler ~procket 33. A sh~ft 308 is also suppoxted on frame
34
WO93/10970 PCT/US92/10~91
f~ 9 9
304 and holds chain dri~e sprocket 35. A drive motorlgear
reduc~r 310, shown attached behind frame 304, drives shaft
308. The motor of motor/reducer 310 is a DC servo-motor
~hat can be precisely controlled. A tensioner 312 and a
plurality o~ support rollers 31~, which are attached to
frame 304, keep chain 300 taut~ As shown in Fig. 12, a drag
brake mechanism 299 is at~ached to frame 304~and acts on
idler sprocket 33 to ke~p chain 300 under ten~ion as it
advances .
Blade 157 is provided near the inlet end of
conveyor 28 as shown in Fig. 1. When sensor 440 as shown,in
Fig. 9A senses half-cell structure 25, conveyor 28 moves to
the right as shown in Fig. 1. For example, the con~eyor
moves to the right a distance of 220-1/2 half-cell structure
pitohes, which pulls about 1.2 meters of continuous half-
cell structure out of the loop at the exit ~nd of adhesive-
applying apparatus 24. The conveyor then stops, and blade
157 traverses the half-cell structure a~ross space 143b
betw~en two adjacent support bars ~41a and 141b as ~hown in
Fig~. lOA and 13, where the advanced blade is hown at 157'.
This cuts the half-cell structure at a position as shown at
line ~50 in Fig. 6 midway between a peak and a valley across
a diagonal surface of the half-cell struckure, so a discrete
sheet of half-cell structure can be picked up by stacker arm
31. Stacker arm 31 then moves over the sheets on the
conveyor and stops closely spaced ~rom the sheets. Conveyor
28 ensures that the continuous half-csll structure is
accurately positioned fsr cutting into sheets by blade 157
and that the cut sheet is positioned for pick-up by stacker
arm 31. Accurate stopping of the conveyor with the half-
cell structure held on bars 141a-141d of the platens is
par~icularly important so tha~ the half-cell structure is
cut along the diagonal surface. This positioning must be
independent of tolerance accumulation from ~ar to bar and
platen to platen, independent of wear that would e~fect the
.:;i,t,,~
WO93/10970 ~ PCT/US92/10191
dimension between platens, and independent of platen and
drive motor inertia and friction variables.
The honeycomb half-cell structure is rut intv
sheets after the adhesive is applied and while ~he adhesive
5 is still we~ and sticky. The cut occurs across diagonal
surface 46 between the adhesi~e-coated peaks along line 150
so that the blade does not contact the adhesive and become
covered with wPt, sticky adhesive that would pre~ent
~, accurate cutting. It should be noted that the cut along the
lO diagonal surface of the pre ent invention is not dependent
t on the application of adhesive. In either case where
adhesive is or is not applied, cutting the half-cell
structure along the diagonal sur~ace achieves the advantage
of preventing waste of half-¢ell structure. A cut can be
~ lS made at the beginning of one sheet and at the end of the
j next sheet after advancing by a distance egual to an integer
plus one-half the pitch of the half-cell structure ~o that
¦ the edges line up, and no trimming is necessary. In
addition, there is no need to flip the sheets of half-cell
20 structure with the pre~ent invention, which reduces
operation time and cost, while still having the ends of the
sheets align for accurate guiding in the stack holder.
Cutting on the diagonal surface of the half-cell structure
; also eliminates the possibility of getting adhesive on the
25 blade or on the end guides for each sheet as they are
stacked, ~ince adhe~ive is never applied to the diagonal
~urfaces. In contrast, when cuts are made on ~he surfaces
where adhesiYe is applied, the blade must cut through the
adhesiYe, thereby accumulatinq adhesive, which must
30 periodically be cleaned o~f. Also, as the cut sheet is
~t~cked, the ends of the sheets which are cut along the bond
ar~a curl up a5 they contact end guide plates. This curliny
up exposes the adhesive to the end guide plates, which
causes sticking of the sheet and/or contaminates the plates
35 for the nex sheet.
36
WO93/10970 P~T/US92/101gl
~.~, 23~,i3
The apparatus of the present invention, by sensing
the position of the bars in conjunction with controlling the
motor speed of the conveyor, ensures accurate s~opping and
positioning of the half-cell structure for cutting. Thus,
in accordan~e with the present invention, the means for
positioning the half-cell struct~re for cutting comprises
means for alternately positioning a bar adj~cent one side of
the cutting means and the other side of the cutting means to
cut acroæs the diagonal surfaces of the structur~.
Preferably, ~hP ~ans for alternately positioning a b2-
comprises a plura.ity of sensors 316, 318, 320, 322, 3
motor Qf motor/re~c~r 310, a rotary encoder 298 as
described below ~. distributed control system 38 as
described above. Alternatively, the means for alternately
~5 positioning may comprise any mechanl~al or electrical
mechanism for positioning a bar on the conveyor. As shown
in Fig. 11, conveyor 28 is provided with a pl~ten sensor
316, a plurality of bar sensors -318 and 320 for sensing
where to stop a 10-bar platen, such as platen 145, and a
plurality of bar sensors 322 and 324 for sensing where to
stop an 11-bar platen, such as platen 139. All of sensors
316, 318, 320, 322 and 324 are mounted on channel 302. As
shown in Fig. 13, sensor 316 is mounted on channel 302 at an
elevati3n ~o it sees a trailing edge 317 of a platen; bar
se~sors, such as 318 as shown in Fi~. 13, are mounted on
channel 302 at an elevation so they see an edge 319 of the
bars on each platen. During advancing of the continuous
half-cell structure, chain 300 is traveling at high speed,
o it must be slowed before stoppiny. Conveyor 2~ is
indexed the approximate dis~ance of a sheet, as determined
for instance by ro~ary encoder 298, which is disposed on
shaft 308 as shown in Fig. 12. The motor of motor/reducer
310, encoder 298 and ~ensors 318, 320, 322 and 324 ars
operatively connected to dis~ributed control system 38.
Sensor 316 senses when the trailing edge of the platen
preceding the one for cutting has passed. When sensor 316
W~93/10970 ~ 2 3 8 ~ ~ PCTSUS9~/10l91
senses the trailing edge of the last platen preceding the
one where cutting is to occur, the motor of motor/reducer
310 i~ c~mmanded ~y distributed control system 3B, as shown
in Fig. 1, to run at a slow speed. Sensor input from all
sensors is ~hen moni~oredO I~ the distributed control
system expects to cut on a ten-bar platen, sensors 318 and
320 will both be 'lon" when sensor 318 sees ~Xe leading edge
of bar 141c and sensor 320 has not yet s~en the space beyond
the trailing edge of bar 141d several bars awayO The choice
of which bars to look at depends on the space available on
channel 302 for mounting and adjusting the sensor hardwar~.
At this point, the motor o~ motor/reducer 310 is commanded
to stop. When stopped, bars 14la and 14lb on platen 145
downstream of the sensors are properly positioned at the
blade for cutting across the diagonal surface of the half-
cell structure at the upstream side of bar 14la on platen
145 as ~hown in Fig. lOB. The use o~ two bar sensors and a
platen sensor for determining ~hen to stop the conveyor is
useful fox providing a large margin of variability for
response of distributed control system 38 to the sensors.
In addition, they can detect malfunctions of tha conveyor if
sensor 320 sees beyond the trailing edge of a bar, which
indicates the conveyor has moved too far and is inaccurately
positioned for cutting. If a very fast control system were
used, only one sensor, such as sensor 316 which senses the
edge of a platen, could be reliably employed to stop the
conve~or accur~tely, and other means could be used to detect
mal~unctions.
With the conveyor accurately stopped, the blade
can cut across the half-cell structure on 10-bar platPn 145,
thereby separating a sheet of half-cell structure and making
it available fsr stacking. When ~his sheet is transferred
to the stacking apparatus, ~he conveyor is free to advance
the hal~-cell structure forward one sheet length again by
indexing a plurality of pla*ens and this time stopping at an
ll-bar pl~en 13g. To stop.at an 11-bar platen, sensors 3~2
3B
WO ~3/1~970 PCr/US92/10191
~ l ,3~
and 324 are employed in conjunction with platen sensor 316
to monitor the position of a different pair of bars, which
are at a dif f erent position epaced one-half pitch of the
half-cell structure away from the bars sensed ~y sensors 318
5 and 3 2 0 usea on thP previous ~top . The process f or stopping
is the same as previously d~scribed, except sensors 322 and
324 are employed instead of ensors 318 and' 320. When
stoppedt bars 141a and ~41b on ll-bar platen 139 downstream
of the sensoxs are properly positioned at th2 blade f or
10 cutting across the diagonal surface at the upstream side of
bar 141b on plat~n 145 as sho~rn in Fig. lOC,
The cutting apparatus of the present invention
further includes a diff erential pressure system for holding
the half-cell structure on the conveyor while advancing the
` 15 half-cell structure and cutting the continuous structure
into sheets and for disengaging the sheets from the conveyor
j during pick-up by stacker arm 31. The differential pressure
system is shown generally at 334 in ~ig. 1. and include~, as
shown in Fig. 12, a plurality of pressure sources 336a-c,
valves 338a-c, blow~off vents 330, 331 and 332, vacuum
. sources 341a-c, valves 343a-c and vacuum ports 171, 173 and
~ 333. Pressure sources 336a, 336b and 336c are connec~ed to
¦ valves 338a, 338b and 338c, respectively, for controlling
the air flow therefrom to blow-oîf vents 332, 3~1 and 330,
2~ respectively. Vacuum ~ources 341a, 341b and 341c are
connected to valYes 343a, 343b and 343c, respectively, for
controlling the vacuum thereto to vacuum ports 333, 173 and
~, 171, respectively. Valves 343a-c and 338a-c are controlled
¦ by distributed control system 38. For explanation, only
; 30 three vacuum ports and three blow-off ~ents are described,
but more or le~s could be used. Each vacuum source can be a
I separate vacuum blower or pump, or a single pump can be
J manifolded to all of valves 343a-c. Similarly, each
¦ pressure source can be a separate compressor or blower, or a
35 single compressor can be manifolded to all of valves 338a-c.
The vacuum applied through ports 171, 173 and 333 holds the
39
'.'' ~'~,
~:` WO93/10970 P~T/US92/1019l
:, ........................................................................ .
.:
half-call strurture on the ConYey3r until the structure is
cut and stacker arm 31 is ready to pick up the cut sheet, at
which time ~he vacuum applied through ports 171 and 173 is
turned off and the prassure to blow-off vents 330, 331 and
332 is turned on to transfer the sheet to the stacker arm.
The vacuum applied through port 333 remains on continually
to hold the l~ading edge of the half-cell structure on the
conveyor.
At least one of spaces 143a formed between platen
.7 10 bars l~ e and 141f includes an opening disposed in fluid
:~ communication with the differential pressure system. The~
, ;, . :. 1
:,, opening may comprise a plurality of ports 159 as shGwn in
Figs. lOA and lOB. Claarances associated with joints 146
`;3
between platens also act as ports. Preferably, at least one
15 space has at least one port formed in the bo~tom surface
thereof, and the port is in communication with the
differential pressure system. As shown in Fig. lOA, ports
159 are formed in the bottom of the spaces. The spaces
between the bars comprise at least one cutting space 143b as
20 hown in Fig. lOA, and the blade and the cutting space are
dispo~ed in horizontal alignment when the bar i5 positioned
at the blade. A vacuum from differential pressure system
334 is applied through ports 159 in each space on both sides
of cutting space 143b. Preferably, the vacuum source is
.~ 25 applied only ~hrough the ports in ach space on both sides
of the cutting space. If there is a vacuum applied at the
space where the cut is made, it would pull the cut end down
~,~ after cutting, so the sticky adhesive-coated peak would
~-~ contact the side ~f a bar and would stick there, which is
~:~ 30 undesirable.
Th~ plurality of ~acuum ports 171, 173 and 333 and
-~ the plurality of blow-off vents 330, 331 and 332 ~re sho~n
';',. 'r ~
3 in Figs. 11 and 12 mounted to channel 302 and are in fluid
~j communication with platen manifold 175. A baffle 335 is
; ~ 35 provided in manifold 175 as s~own in Fig. 12 to shield the
effect of adjacent blow-off vent 332 from the vacuum
:~, 40
~;, -,
,......
I- i W~ 93/1~J197~ PCI`/I~S~2/10191
`~
' '.`
.; supplied by vacuum port 333. This arrangem~nt of
,~ individually controlled vacuu~ ports and blow-off vents
~`:. permits indepPndent offon operation of each ~acu~m port and
blow-off ~ent without losing control of the leading edge of
the continu~us half-cell R~ructure.
In accordance with the present invention, th~re is
~i provided a proce~s for cutting a hQneycomb h~lf-cell
.~1, structure into a plurality of sheets. The process compris~s
. the steps of positioning a length of the half-~ell structure
~,; 10 so that the diagonal surfaces of the half-cell structure are
~` positioned for cutting adjacent a blade, such as blade 15~,
:~ and cutting the half-cell structure across the diagonal
. surface to form the sheets. The half-cell structure is cut
across the diagonal surface alternating between one side and
~, 15 the other of a predetarmined bar, such as platen bars 14la
; and 141b. The half-cell structure is position~d on a
.-,~; conveyor, such as conveycr 28 as described above, ~nd the
conveyor is advanced by ~n integer number plus one-half of
the pitch of the half-cell structure. A vacuum, ~uch as
that from ~acuum sources 341a-c, is appl~ed to ~he half-cell
structure via ports 159 to hold the half-cell structure in
~ place while it is cut and advanced. The structure i~ placed
r~ on the conveyor, which, as described above, has a plurality
oP bars, such as 141a-141d, which contact the valleys on one
side of the half-cell structure and a space, such as 143a
, ~nd 143b, between each consecutive bar. At least one of the
~ spaces comprises a cutting space, such as cut~ing space
.. ~1 143b, ~hich is disposed in horizontal alignment with the
~ blade when the conYeyor stops advancing. The conveyor is
,,~,/ A 30 stopped at the cutting space, and the vacuum is applied
,-1 through the ports in each space adjacent the cutting space.
j It is ~re~erable that the Yacuum i5 applied only through the
¦ ports in each space on both sides of the cutting space.
.;., Further in accsrdance with the present invention,
. 35 there i8 provided a honeycomb core made by positioning the
.,,~ ,~
;~1 hal~-cell structure so that the diagonal surfaces of the
,''~i ' ,
,, 41
",i,.,;~
;-", .
::~
- W~93/10970 PCT/US92tlOlgl
_~ ~ L ? ~
'': `'
half-cell structure are positioned adjacent a blade for
:- cutting and by cutting the halfcell structure across the
-. diagonal surface to form the sheets. This core is
illustrated in Fig. 2 as described above, where cut diagonal
i,....
.`` 5 surfaces ~6, 4~' of ~he sheets are aligned at ~he edge of
.~ the core at 297 as a direct result of ~he assembly process.
~-'. The principles employed in th~ conv2yor of the
~ present invention may be extended to any system for
`.~ advancing the leading edge of a supply of corrugated web,: . ,
:; 10 which may be other than honeycomb half-cell structure.
~;~ Thus, in accordance with a further embodiment of the pres~nt
~ invention, thexe is provided a system for advancing the
:~ leading edge of a supply of corrugated web which has a
plurality of alternating peaks and valleys, where the system
positions the web for a secondary operation. Such a system
! ' ' ',
;`~... ; is shown gsnerally at 28 in Figs. 11 and 12. The secondary
~ - opsration may include a cutting operation to cut a discrete
~ .i.. t .
i sheet from the web, such as that performed by blade 157 as
described above. Other ~econdary operations may replace the
~ 20 cutting operation or be in addition to the cut~ing
'"'~`,'3 operation, such as a marking operation, an adh~sive-applying
.~'~ operation or a folding operation.
~, The advancing system of the present invention
-, comprises endless loop conveying means including a plu~ality
.` 25 of 5paced support bars for contacting the Yalleys of the
web, where the conveying means has an entrance end and an
..:~
.:' exit.end. Preferably, the conveying means comprises a
~, conveyor, such as conveyor 28 as described above and as
shown in Figs. 1 and 10 - 13, which includes spaced support
-s 30 bars, such as 141a-141f as described above, ~or contacting
the ~alleys of the web. In the advancing system of the
present invention, it is preferable that they contact only
the valleys o~ the web. A space, such as spaces 143a and
143b a~ described above, is formed between each conse~utive
~ , 35 bar. The space has a depth greater than the height of each
r~ ~ peak o~ the web. The csnveyor of the advancing system of
~:~ , 42
,~,',1,
~' ~
W093/10970 PCT/US92/10191
8 ~ ~
the present invention comprises a plurality of platens, such
as platens 139 and 145, where the support bars are formed on
the platens. The number of bars on each consecutive platen
alternates between an odd and an even n~ber.
T~e advancing system of the present invention
further includes holding means for holding the web against
the support bars. Preferably, the holding m~ans comprises
at least one vacuum source, such as vacuum sources 341a c as
described above, for holding the web against support bars
~. 10 141a-f. The advancing system of the present invention also
i, includes means for disengaging the web from the support
bars. Preferably, the disengaging means comprises at least
one pressure source, such as pressure sources 336a-c, for
1 disengaging th~ web from support bars 141a-141f. The
~ 15 advancing system of t~ present invention further includes
i means for selectively activating and de-activating the
holding means and the disengagin~ means to remo~e the cut
shset of web ~rom the support bars. Preferably, the means
f or selectively activating and de-activating the holding
20 means and the disengaging means comprises a plurality of
valves 338a-c and 343a c, which function as described above.
The ad~ancing system of the px.~.sent invention also
. comprises advancing means for repeatedly advancing the
conveying means and the leading edge of the web from the
3 25 entrance end of the conveying ~eans to the exit end thereof.
The advancing means preferably comprises a motor, such as
the motor of motor/reducer 310 as described above, and a
distributed control system, such as distribu~ed control
system 38 as described above. The advancing system of the
30 present invention also comprises stopping means for
rspeatedly stopping the advancing means after a
i prede~ermined number of sup~ort bars have advanced past a
po~ition for applying the condary operation to the web.
Preferably, the ~topp'~:g means comprises a rotary encoder,
35 such as ro~ary encoder 298 as described above, and a sensor,
such a~ any one of sensors 31B, 320, 322 and 324 as
43
WO93/1097~ 3 P~T/US92~10191
,
; described above, for sensing the presence of a support bar
:^.
. near the position for applying the secondary operation. The
`~i motor, tha encoder and ~he sensor of the advancing system of
-` the present invention are operatively connected to
~: 5 distributed control system 38.
In accordance with the present inve~tion, there is
provided a method of advancing the leading edg!e of a supply
of corrugated web having a plurality of alternating peaks
and valleys and of handling the web for a secondary
-~ 10 operation.... The method comprises the step of engaging the
.~ leading edge of the web at an entrance end of a conveyor, ~
such as conveyor 28 as described ~bove. The entrance end of
~ the conveyor can be anywhere from near idler sprocket 33
.~ where the web first contacts the conveyor to just adjacent
the secondary operation, such as adjacent blade 157 as shown
~ in Fig. 12. The leading edge of the web is advanced as the
.~l leading edge moves from the entrance end to an exit end of
the conveyor a distance equal to an integer plus one-half
`I the pitch of the web. The conveyor is advanced by a
~ 20 distance equal to an odd number of conveyor platens. The
.'1 valley~ of the web contact a plurality o~ support bars
:: ~ormed on the conveyor for suppsrting the advancing web. It
~, is prefera~le that only the valleys of the wPb contact the
j support bars. The advancing web ~s held against the support
bars and is stopped to position the w b adjacent the
secondary operation at the entrance end of the conveyor.
The secondary operation includes cutting a disc~ete sheet
from the web, such as with blade l57.
~l The holding step includes activating at least one
,~ 30 vacuum source, such as vacuum sources 34la-c. The method of
~, the present invention further includes the step of de-
~; actiYating the vacuum source to release the cut sheet from
the conveyor, and activating at least one pressure source,
', such as pressure sources 336a-c, to remoYe the cut sheet
~rom ~he conveyor. The activating and the de-activating
steps are done progressively from one end o~ the conveyor to
.
.~, 4A
~,
WO93/10970 P~T/VSg2~10191
1~ .3~
th~. other to progressively remove the cut sheet frGm the
conveyor.
In accordance with the present invention, there is
provided a transfer head for holding a sheet of honeycomb
half-cell s~ructure. Referring to Fi~s. 10~, lOC and 14A,
stacker arm 31 includes an axtension rod 31~ and a transfer
head 31b attached to the extension rod. Ext~ension rod 3la
is attached to and i moved by a cylinder mechanism 31c as
~hown in Fig. 1 for motion between a pick-up position 344 at
conveyor 28 and a deposit position 345 at stack holder 32.
Cylinder 31c is supported by conveyor frame 304. Transfer~
head 31b comprise~ a plurality of support bars 162 and 163
that support the ~heets of half-cell structure along the
valleys thereof and provide clearance with the peaks of the
sheets, as do the bars of the f~rming apparatus and the
conveyor. At least one space 161 is formed between each
support bar, where the width of each space is about the
distanc~ b~tween adjacent valleys of the half-cell structure
and the depth of the space is greater than the height of ~he
peaks. Within each bar are ports 164 and 165 spaced along
the length of each bar in fluid communication with a
transfer head manifold 166. Manifold 166 is disposed in
transfer head 31b as shown in Fig. lOB. The transfer head
of the present invention also includes a differential
pressure system for holding the sheets aqainst the support
bars and disengaging the sheets therefrom. ~he differential
pressure syst~m comprises a Yalved vacuum source 167 and a
valved preqsure source 168 as shown in Fig. 15. ~anifold
166 is in fluid communication with vacuum source 167 or
pressure source 168, so that the sheets of half- ell
structure can al~ernately be held securely by vacuum to bars
162 and 163 or blown off the bars by prsssure.
At the end of extension rod 31a is a two-axi
shift mechanism 301 as shown in Figs. l~A and 15 that moves
transfer head 31b up and down and side to side relati~e to
rod 31a. The up position is used to re~eive the half-cell
W093/~097~ P~T/US9~ 191
~ 1238~ ~
sheet from the conveyor, and the down position is used to
place the ~heet on ~he top of tha stack of sheets of ~he
core. During the tra~el between the conveyor and the
stackin~ apparatus, transfer head 31b is in the up position.
The side po itions shift the head by one-half of a half-cell
pitch in the preferred embodLment to pick up alternate half-
cell sheets from the 10-bar and ll-b r platens~on the
conveyor and place them in the stacking apparatus.
Chain 300, which comprises platens 139 and 145
with bars 141a-141f, must have clearances so tha~ the
platens pivot freely relative to each o~her at pivot 146 as
they travel around sprockets ~3 and 35. There is some
variation in dimensions from pivot to pivot and in the
clearances at the pivots. Such pivots also eventually wear,
and the tolerances and clearances may change. These
variations may cause slight differences between the pitch of
chain 300 compared to the pitch of transfer head 31b. If
transfer head 31b were to be lowered into the spaces between
chain platen bars to pick up the half cell structure by
~ngaging the valleys, there may be mechanical int~rferences
between bars 162 and 163 on the transfer head and bars 141a-
141f on.the platens caused by these variations. To avoid
this, transfer head 31b remains in a position above platen
support bars 141a-141f, and the cut sheet of half-cell
~tructure is blown off platen chain 300 and sucked onto the
transfer head.
When it is de~ired to transfer a sheet of half-
c~ll structure from the conveyor to the transfer head, the
transfer head is positioned above the conveyor, and
distributed control system 38 begins the transfer of the
sheet. The present invention employs a progressive transfer
of the sheet of half-cell structure from platen support bars
l~la-141f to trans~er head bars 162, 163 by sequential
vacuum release and pressure blow-off fxom one vacuum zone to
the next along ~he conveyor. Transfer head vacuum 167 is
turned on to receive the sheet. The first step in the
~6
WO~3/10970 PCT/US92/1Ol91
~ 23~
~ transfer process of the present invention is to turn off
vacuum to port 171 and to simultaneously turn on vents 330
and 331. This blows off the end of the sheet, which is
positioned as shown at 342 in Fig. 12 at the drive end of
conveyor 28, and the sheet moves up and is captured by the
vacuum on transfer head 31b created by vacu~m source 167
over that portion of the ~heet. The next si~g~re Yent and
, port are de-activated and activated to blow up the next
3 portion of sheet and so on until, at ~he end of the conveyor
~, 10 where blade 157 is disposed, vacuum to port 173 is turned
~' off, pressure to ~ent 332 is turned on, and the last portiQn
of the sheet is transferred to the transfer h~ad. This
process is very quick and takes less than 0.25 seconds.
This ensures accurate transf er of the sheet even though the
platen chain pitch and transfer head pitch may differ.
~lternatively, the vacuum sources could remain on and
~ sufficient pressure could be supplied to overcome the vacuum
3i applied thereby. During progressive transfer of the sheet,
~- valve 343a remains on continuously so that a vacuum is
continuously applied to hold the leading edge of the half-
~, cell structure in place on the conveyor. The vacuum release
;. and pressure blow-off to the zones moves from right to left
along th conveyor of Figs. 1, 11 and 12, and ~he sheet of
halif-cell structure is progressively transferred from right
to left onto stacker arm 31. It should be noted that even
though the operation of the conveyor and transfer head is
described from right to left, it is within the scope of the
pre~ent invention to operate the system of the presant
invention from left to right.
By progressively transferring the cut sheet, the
~heet is never all freely released; it is always engaged
wi~h one, the other or both of conveyor 28 and stacker arm
31. This ensures accurate, repeatabl~ lacement of the
sheet on the arm. This accuracy is cr_;ical when arm 31
places the next top sheet of half-cell structure on the
already started core 30. Stacker arm 31 is positioned over
WO93/10970 .~ 8 ~i 9 PCT1US92/10191
the core and is lowered to place the transferred sheet in
contact with the core. When the transferred she~t is placed
in contact with the top sheet of ~he core J the sticky
adhesive components lightly ~tick togethar, thereby
preserving the accuracy of placement. Vacu~m source l67 on
transfer head 31b is r~lieved, and air pressure from
pressure source 168 is momentarily applied to Forts l64, 165
in transfer head bars 162 and 163, thereby releasing the
sheet. The stacker arm is then retracted upwardly.
In accordance with the present invention, there is
provided an apparatus for stacking a plurality of sheets of~
half-cell structure to make a hexagonal-cell honeycomb core.
As noted above, the stacking apparatus of the present
invention is shown at 29 in Fig. 1. The apparatus comprises
means for stacking the half-cell structure so that as one
sheet of the half-cell structure is placed on the top of a
stack comprising at least one sheet of the half-cell
structure, the peaks of one sheet contact the peaks of an
adjacent sheet. It should be noted that ~he half-cell
structure may, in this context, comprise discrete sheets or
a continuous supply. The stacking means comprise stacker
arm 31 and stack holder 32. Figs. 14A, 14B and l5 are
cross-sectional views of the stacX holder of the present
invention in greater detail. As shown in Fig. l~A, the
stack holder comprises an enclosure surrounding the stacked
sheets for restricting the flow of air around the periphery
thereof~ An enclosure is shown at 34 in Fig. 14A which
compri6es an upper portion 185 disposed above the top of the
stack o~ shee~s and a lower portion 187 disposed below the
top of the stack.
The stacking apparatus of the present invention
fur~her includes an elevator 170 as ~hown in Fig. 14A that
comprises a platform 172 having a plurality of guide rods
174 and an elevating screw 178. The stacking apparatus also
includes a plurality of end guide plates 176 disposed in
contact with the sides of the core. Each guide rod 174
4B
i
1,j,,7 ~
; W~93/l097~ ~CT/US92/~0191
~ f ~ ~ 9 9
: passes through a linear bearing ~80, and screw 178 passes
through a dri~en nut 182g which dr.ives the screw and
attached platform 172, plates 176 ~nd rods 174 up and down.
A plurality of auxiliary guide rods 18~ are fix~d to lower
portion 187~of stack holder enclosure 34. When the sheet~
of half-cell structure are placed in the stack holder
elevator, they are placad on the back of platform 17~ in
contact with guide rods 174 and spaced from auxiliary guide
. rods 184.
The stacking apparatus of the present invention
also comprises dif ferential pressure means disposed beneath
~ the stack for reducing the air pressure surrounding the
.~ stack to a pressure below the air pressure on the top of the
stack for pressing the sheets together to form the core.
Preferably, the differential pressure means comprises a
blor r l90a and a circulating blower 190b as shown in Fig.
' 14A. Blower 1~0a creates a vacuum on the side on which it
,j communicates with duct 188 and a pressure on the side on
;j which it communicates with duct 189 and duct 212 as shown in
Fig. 14A. Circulating blower 190b enhances the flow of air
from blower 190a into duct 186. The application of a vacuum
to the stack provides a consistent, ev~nly distributed force
3 tD press the sheets of half-cell structure together to form
J~ an accurate core.
;~ 25 The purpose of end guide plates 176 is to prevent
; excess air flow at ~he ends, to register the ends of the
~ a~embled core for alignment with the next sheet of half-
;~ cell structure, and to avoid disturbing the ends of each
I sheet as it is lowered onto the core. Preferably, the
surfaces of the end guide plates are roughened, i.e.,
roughened enough to oppose the vacuum forces applied to the
i shsets by vacuum source 190a. The roughened sur~aces
pro~ide a ~riction ~orce that opposes and balances the
vacuum ~orce on the cut ends of the sheet. One preferred
end guide plate sur~ace comprises a rough, cured silicone
adhesive which is about 0.08 cm. thicX. Another surface
; 4~
WO93/10970 J ~y ~9 PCT/uC92/lol9l
comprises a plurality of knurled strips running the length
of the plate.
The apparatus fur~her comprises heating means ~or
heating the sheets while the sheets are being stacked. The
heating mea~s comprises a heating element disposed in at
least one of the upper portion and the lower portion of ~he
enclosure. ~ heating element 196 is shown i~~~ig. 14A
disposed in lower portion 187. Lower portion 187 also
includes a circulating fan 198 which pulls air down pas~
heating element }96 and directs ~he flow against the bottom
of enclosure 34. A heating element 464 is also disposed in
duct 186, which maintains the heat in duct 186 and lower
portion 187. In the preferred embodiment using the above-
described adhesive system, heating element 464 maintains the
temperature at about 170 - l90 degreès C. Maintaining this
temperature also allows the adhesive to continue to cure and
the air in the stack holder to remain dry to prevent
moisture absorption by the sheet, which causes undesirable
expansion of some of the materials from which the half-cell
structure is ~ormed.
In addition, the stacking apparatus of the present
invention includes heati~g means for heating air leaking
through the enclosure. The means for heating the air
leaking through the enclosure preferably comprises a duct
189 as shown in Fig. 14A which is communication with upper
portion 185 of the enclosure. ~uct 189 has a low flow of
air heated to about 170 - l90 degrees C in a preferred
smbodiment and thus limits the inflow o~ unheated room air
that would quench the sheet temperature. Duct 189 must
include a heating element if air is drawn into this duct
from *he atmosphere. Alternativ ly, air may be re-
circulated from heated duct 186, through duct l88, to duct
lB9, in which case duct 189 does not require a heating
element and functions only as an air duct. A side panel l9l
is provided on upper portion 185 to allow access for stacker
iarm 3l as each sheet is available for stacking. As shown in
~ 50
WO93/10970 PCT/US92/10191
?~ 3~9
FigO 14A, a gate 193 is provided on ~nclosure 34 at the
junction of upper and lower portions 1~5 and 187,
respectively, to adjust the amount of ~ir that can freely
flow from duct 189 into lower portion 187 and through the
, 5 co~e. Afte~ each sheet of hal~-cell structure is placed on
t the cor~, the elevator i5 lowered by driven nut 182 until
the top of the just-placed sheet is detected~ a plurality
of vertically stacked emitters 192 and rec2ivers 194, which
function as upper and lower sensors. The upper emitter and
. 10 receiver are just uncovered and the lower emitter and
receiver ret-~in co~i-^~ed when control system 38 signals the.
elevator tc -~op. This is repeated for each sheet~ As a
~ result, the core is gradually lowered out of the air stream
I from duct lB6.
~ 15 By stackir.g in a heated enclosure, rapid adhesive
3 curing as each sheet is stac-~d is ensured. Also, stacking
in a heated enclosl~re keeps e core dimensionally stable,
since sometimes moisture anc~ ~emperature effect shèet
dimensions signif icantly. Applying a vacuum while stacXing
results in a pressu-e differential between the top of the
top sheet of the core and the rest of the core that presses
~ and holds the just-placed sheet firmly on the core. This
¦ dif*erential pressure ensures good contact between the peaks
of the sheets of half-cell structure, so the first and
second adhesive components can combine and cure to form a
strong, reliable bond. Thus, stacking in a heated enclosure
where a vacuum is app~ied achieves an accurate finished core
~ without added edge-aiigning dents or holes of the prior art
¦ that must be removed from the final product after bonding
and before the final use thereof. The core, as it is
assembled, is spongy in the vertical and machine directions
and is rigid only in the transverse machine direction. As
the height of ~.he core increases, the vertical sponginess
may increase. :f the stacXing forces and the half-cell
alignment are not controlled carefully, deformation and mis-
registration in the core make stack formation from
~i
WO93/10970 ~ ~ 3 8 ~ 9 P~T/US9~/1019J
individual sheets poor or impossible. The reduced pressure
caused by the vacuum created in duct 188 provides the
required stacking force control and also ~irmly presses the
to p sheet against the core ~o achieve good ~onding contact
5 as the adhesive components post-mix and start to set,
accelerated by thP elevated temperature of the air flow from
duct 186. ,-~-
After the core is fully formed, ele~ator 170 is
raised, and a side door 200 provided on upper portion 185 of
10 enclosure 34 is opened to permit removal of the completed
core. Stacking apparatus 29 i5 then shut down while the
core is removed. Platform 172, which comprises a foraminous
block, such as a dummy piece of honeycomb, is prepared for
I the next core by placing a flat sheet of paper or a thin
'i 15 stainless steel sheet on the top of the foraminous block.
J This blo~k allows stable air flow from duct 186 to duct 188
at start-upO When the first sheet of half cell structure is
placed on the top of the block by stacker arm 31, it sticks
,i to the sheet placed on top of the block, which ensures that
20 dimensional accuracy.is maintained for alignment with ~he
¦ next sheet of half-cell structure.
j After removal from the stack holder, the completed
J core may be placed in an oven for further curing to achieve
maximum bond strength. An alternative to shutting down the
25 stacking apparatus for core removal is to provide two stack
holders and to alternate stacking between them. Another
alternative is to replace the elevator platform with a long
heated enclosure with moving endless walls and to provide
~1 ~acuum and thermal seals around the exiting honeycomb core
30 so it can be continuously removed and periodically cut off
from the already formed core.
Fig. 15 shows an enlarged cross-sectional view of
stack holder 32 of Fig. 14A in order to more completely
explain how the differential pressure source is applied to
35 press the sheets of the core together. Illustrated in Fig.
15 are a down-flow chamber 202 provided in upper portion
52
,~ .
WO93~10970 PCT/U~2/10191
3 9
185, a ~cross-flsw chamber 204 provided betw~en ducts 18Ç and
188 and a holding chamber 206 provided below ducts 186 and
188. Cross-flow chamber 204 and holding chamber 20~ are
part of lower portion 187 of enclosure 34. The ass~mbled
core, which~is shown supported on elevator platform 172 in
Fig. 14A, is positioned wi~h the top sheet of the core
outside cross-flow chamber 204 in stack holder~32. The
pressure, P lo, in the cross-flow chamber 204, is below the
press~re, P-hi, in down-flow chamber ~02. Core 30 passes
through an op~ning 214 formed between down flow chamber 202
and cross-flow chamber ~04. A plate 195 as shown in Figs.
14B and 15 is provided in enclosure 3~. Plate 195, in
additisn to adjustable ga.~ 1~3 and end guide plates 176,
restrict fluid flow and c r ine opening 2~4 around the
periphery of the top of the core. Air flows from down-flow
chamber 202 to cross-flow chamber 204 ~hrough opening 214
all around the periphery of core 30, so the pressure in
I enclosure 34 c~anges from P-hi in down-fl~w chamber 202 to
j P-lo in cross-flow chamber 204 and holding chambe~ 206.
This pressure d~f~arential from P-hi to P-lo produces a load
on the top shee~.s of the core, which load is transmitt~d
through the ent~.e core. The force resulting from the
differential pressure is continuously exerted on the
remaining core ~ hold it together during heating and curing
¦ 25 in the stack ho~.~er.
¦ ~ccording to the present invention, ~here is
I provided a process of making a haxagonal-cell honeycomb core
Il rom a half-cell structure. The proce~s comprises the steps
of stacking the half-cell structure so that as one sheet of
half rell structure is placed on the top ol a stack
comprising at least one sheet of half-cell structure, the
peaks of one sheet contact the peaks of an ad~acent sheet
I and restricting the flow of air axsund the periphery of t.~e
I stack, such as with enclosure 34. The stacking step
includes stacking the sheets in an enclosure, such as
enclosure 34, that restricts.the flow of air past the top of
53
7 ~
WO93/10970 )i~ ~3 8 ~ 9 PCT/US92/1019l
the stark into ~he enclosure. A differential pre sure force
i~ then applied ~o the sheets, such as by blower l90a,
during the stacking ~tep to press the sheets together,
thereby forming the core. The differential pressure force
5 applied to he sheets may be opposed at the ends of the
sheets, as by roughened guide plates 176. The process
further includes the step of passing a cross flow of hot
gas, such as through ducts 186 and 188, through the stack
during the ~tacking step to rapidly heat the shee s. The
10 process also further includes the step of heating the air
, passing into the enclosure surrounding the core, such as
¦ through duct 189 and upper portion 185.
In accordance with the prasent inv~ntion, there is
provided a process of transferring a plurality of sheets of
15 half-cell structure. The process comprises the steps of
contacting the valleys on one side of the sheets of the
~ half-cell structure with a plurality of spaced bars, such as
3 bars 162 and 163, formed on a transfer headt such as
j transfer head 3lb, and holding the structure against the
¦ 20 bars. Preferably, the bars contact the entire valley of the
¦ half-cell structure. ~ differential pressure force, such as
from vacuum source 167, is applied to the sheets through
I ports, such as 164 and 165, in the bars. Alternatively, the
vacuum may be applied through the spaces bPtween the bars,
25 such as paces 161. The peaks of one side of the half-cell
structure are placed in the space between the bars, where
the space has a width which is about the distance between
adjacent valleys, and the space is dseper than the height of
the peaks. The sheets may alternatively be adhered to the
30 spaced bars with a temporary adhesive applied to the bars;
when the sheet is released from the bars, the valley of the
sheet is separated ~rom ~he adhesi~e. Alternatively, the
sheets may be adhered to the spaced bars with a plurality of
clamps and when the sheet is released from the bars, the
35 valley of the sheet is separated from the clamps. The
~ransfer head and the layer are moved from pick-up position
$
~ 54
WO93/1~970 PCT/VS92/101~l
344 in Fig. 14A to deposit position 3~5 as shown in Fig.
14A spaced from the pick-up position. The sheet is then
released from the b~rs.
~ An alternate embodiment of the present invention
ii 5 is shown in Fig. 16. Whenev~r possible in Fig. 16, elements
like the elements Df the ~mbodiments of Figs. 1`- 15 will be
used, bu~ will be designated with a prime. ~n~the
embodiment of Fig. 16, a diff~rential pressure source is not
used in the stack holder to press the top sheet t~ the core.
~, 10 ~ather, the transfer head is allowed to dwell with the top
sheet of the core for a brief time until the adhesive star~s
'~ to gel before releasing the top sheet. A stacking apparatus
i5 shown in Fig. 16 and includes a stack holder 32' and a
stacker arm 31'. Stacker arm 31' includes an extension rod
31a!, a transfer head 31b' and a two-axis shift mechanism
301' which function as described above with respect to Figs.
lOB, lOC and 14A. The transfer head of the embodiment of
¦ Fig. 16 may include heating means for heating the bars.
Preferably, the heating means comprises a heating coil 470
as shown in Fig. 16. The heating means may also comprise
other types of heat sources, including, but not limited to,
a radiant heater or a rssistance heater. Alternatively,
heating tape may be wrapped around the periphery of the bars
of the transfer head for heating the bars.
Stack holder 32' also comprises a lower portion
187~ of the enclosure for the stack holder. Disposed in the
3 bottom o~ lower portion 187' is a heating element 196' and a
I circulating fan 198' for conditioning the air in ~he stack
holdsr. An elevator 170' for raising and lowering the core
is provided in lower portion 187', which includes a platform
172' and at lsa t one guide rod 174' disposed in a linear
bearing 180' and at least one auxiliary guide rod 184'. The
elevator functions as described above with respect to Figs.
14A, 14B and 15. An emitter 192' and a receiver 194' are
provided adjacent core 30' below linear bearing 180' for
sénsing the position of the core. Preferably, at least on`e
,~,
WO93/10970 PCT/US92/10191
~1~3~99 :~
end guide plate l76' is provided for ensuring accurate
alignment of the sheets as they are stacked.
In the embodiment of Fig. 16, transfer head 3lb'
is allowed to dwell with the top sheet in contact with the
core for a ~rief time until the adhesive starts to gel
before releasing the top sheet. The head dwell ensures that
the position of the top sheet on the core is'r~tained and
will not shift as the core is lowered on the elevator as the
adhesive continues to cure. Transfer head 31b' may also
tra~el downwardly with the elevator before releasing the top
sheet on the core. The head is preferably heated, otherwi~e
it acts as a heat sink for the sheet. Alternatively, when
i the adhesive system used with the embodiment of Fig. 16 does
not require heat for curing and maintaining the half-cell
structure in a dry state so that it will not expand, the
transfer head of Fig. 16 may be used without heat. Also
f alternatively, the head could be a thermal insulator that
would not conduct heat away from the sheet. The adhesive,
whether a one-component or a two-component system, is
preferably ~et and sticky when the top sheet contacts the
core to ensure a large adhesive contact area is quickly
formed. However, when the transfer head of Fig. 16 is used,
'~ the need for a sticky adhesive for maintaining an ac~urate
sheet position is decreased.
~ 25 The operation of the cutting apparatus and the
¦ stacking apparatus of the system of the present invention as
shown in Figs~ 5 will now b~ described with respect to
~ Fig. 17. In normal operation, the half-cell forming
I apparatus and the adhesive applying apparatus of the present
i 30 invention run continuously and at the same line spee.d. In
describing the timing diagram of Fig. 17, it will be
appreciated that there are many components involved and that
there may be several events for each component, 50 that many
events occur at the same time. This is done to optimize the
1 35 cycle time o~ the system; each could be done sequ~ntially,
i but ~ore time would be required.
i
~ ~6
)
_'~J.',
~ W~93/10~70 PCT/US~2/10191
~ 23839
Fig. 17 shows several cycles of operation,
starting at an arbitrary zero time when conveyor ~8 begins
to advance a ~hset-len~th of thP continuous half-cell
structure. One complete cycle of operation consists of two
consecutive~sheet advances, one where the cut occurs on one
side, such as the upstream side, of a conveyor platen bar,
and one where the cut occurs on the other si~e, such a~ the
downstream side, of another bar. This requires a lateral
shift of one-half the pitch of the half-cell structure in
. 10 transfer head 31b to pick up and stack the sheets. The
typical time ~or a repeatable cycle of operation is best
referenced to the transfer head shift event and is shown at
216 in Fig. 17. This cycle time is about 3.8 time units on
the diagram of Fig. 17.
lS Fig. 17 will be describ d looking first at one
time unit interYal and examining the components and the
events associate~ therewith ~enerally from top to bottom of
the diagram. First, from t_~e O to tim~: 1, the following
events occur. The conveyor advances the distance of one
29 sh~t of hal~-~ell stru~turP and stops. The conveyor then
starts to dwell, waiting for the blade to cut a sheet from
~ the continuous supply of hal~-cell structure and the
J transfer head to pick up the sheet. The blade stays in a
, retracted position, waiting for the conveyor advance to be
¦ 25 completed. Vacuum sources 341a-c of the conveyor of the
~ cutting apparatus ~tays on to securely hold the advanced
3 hal~-cell structu~ before pick-up by transfer head 31b.
The conveyor air fr4m pressure sources 336a-c for
~ transferring a cut she~t to ~r~nsf~r head 3lb stays off.
¦ 30 The trans~er head, which picked up the last sheet at the
downstream cut, stays ~t that shift position for stackina.
; Enclo~ure side panel 191 goes rom closed to open to admit
:~ the ~ransfer head inside enclosure 34 for stacking. The
¦ tr~n~er head, which is holding the 'ast sheet, continues
35 movirig to stack holder 32 and arri~ there while conveyor
¦ 28 is still advancing. Elevator 170 continues moving down
57
I
,~
WO93/10970 PCr/US92/1~191
~,'i23~3~g '`~`
until the e~rlier stacked sheet is at the proper elevation
~or stacking the next sheet; the elevator dwells at this
elevation. When the transfer head is at stack holder 32,
and elevator 170 is at the dwell event, the transf~r head
5 goes to the~down position to place the sheet on top of the
stack. When the transfer head is down, vacuum so~rce 167,
which had been holding the sheet securely on,t~e head, is
~ turned off. At the same time the transfer head air from
f pressure ource 168 is turn d on to positively release the
10 sheet from the head, which is still down. The transfer head
goes to the up position while the transfer head vacuum
remains off and the transfer head air remains on. The
transfer head, having released the sheet in stack holder 32,
starts to move from s~ack holder 32 to conveyor 28, which
15 may ~e just before the conveyor reaches the dwell event.
Elevator 170, having received the sheet from the transfer
' head, starts moving down.
The following evsnts occur from time 1 to time 2
in Fig. 17. Conveyor 28 stays at the dwell Pvent while
20 blade 1~7 and transfer head 31b interface with the half-cell
, structure on *he conveyor. The blade extends across the
i half-cell structure on the conveyor, thereby cutting through
s, the structure to cut off a sheet. The blade then retracts
~ back through the cut to return to a retract event position,
s 25 out of the way of the conveyor bars and the trancfer head.
The transfer head starts to shift to an upstream event
' position while the transfer head is moving to the conveyor,
i since the sheet to be picked up was just cut at the upstream
side of a ~on~eyor bar. This conveyor bar is one--half of
30 the pi~ch of the half-cell structure away from the position
of the bar supporting the sheet adjacent the previous cut.
Side panel 191 closes as soon as the transfer head is clear
as it mo~es to the conveyor. As the transfer head is moving
t9 thP co~veyor from the stack holder, transfer head
85 pressure source 168 is turned off, and trans~er head vacuum
source 167 remains off. Th transfer head arrives at the
53
I W093/10970 ?-~ 23~39 PCT/US92/1019l
conveyor over the cut sheet after the blade has retracted.
The head has shifted so the transfer head bars are
positioned over the spaces on the conveyor platens.
Transfer head vacuum source 167 i~ then turned on. Vacuum
sources 343~ and 343c are then turned off, and pressure
sources 336a-c are turned on progressively from one end of
the sheet on the conveyor to the other to th~reby
progressively transfer ~he sheet from the conveyor to the
~ transfer head as described in detail above. Transfer head
i~ 10 vacuum source 167 stays on to hold the sheet, which has been
transferred from the conveyor. The transfer head pressure~
source stays off. The transfer head, after receiving the
sheet from the conveyor, starts to move to the stack holder.
The conveyor then starts to advance.
}5 The above description explains about one half-
cycle of operation; a full cycle is a repeat of this half-
cycle, except that the transfer head shift is different.
t The full cycle keeps repeating until there are sufficient
¦ sheets stacked to complete the core, which can be determined
1 20 by having distributed control system 38 keep track of how
¦ many sheets have been stacked. When the core is comp~eted,
I the stacking apparatus is shut off, the enclosure side panel
¦ raised, and the stacker elevator raised æo the comple~ed
I core may be removed from the stack holder.
¦ 25 Other embodiments of the invention will be
apparent to those skilled in the art from consideration of
~' the specification and pra~tice of the invention disclosed
¦ herein. It is intended that the specification be considered
as exemplary only, with a true scope and spirit of the
invention being indica~ed ~y the following claims.
~9
