Note: Descriptions are shown in the official language in which they were submitted.
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STD 302 PA -1-
APPARATUS FOR SE~LING FORM SHEETS
Background of the Invention
The present invention relates to the production of
multi-page business forms, mass mailers and the like and in
particular, to an apparatus for conveying and sealing into
sealed form sets a plurality of sheets having heat sealable
glue thereon.
Multi-page sealed form sets have been produced on
var-ious apparatuses from sheets of matched and mismatched
lengths, as well as from a plurality of webs or singlej folded
webs-. Typically, form sheets in a form set are attached by
adhesives along at least one edge. The development of heat-
sealable and heat-activated adhesives which are particularly
suited for use in~office environments has lead to improvements
in production methods and apparatuses in which such adhesives
are used.
-- By way of example, Shultz, U.S. Pat. No. 4,818,332,
- dis~loses an apparatus for aligning, conveying and sealing
collated matched and mismatched form sheets into form sets, at
20-- least one of the form sheets for each set having heat sealable
adhesive thereon. Aligned,-assembled form sheets are
overlapped in shingle fashion, and fed by pressure rollers
between fixed, heated platens to soften the adhesive. Sealed
form sets emerge from the heating structure onto an outfeed
conveyor, and remain shingled until reaching a rack where they
are stacked.
-- Knox et al, U.S. Pat. No. 4,420,147, discloses an
appara~us for folding and heating a continuous form weh. The
web is folded and passed between a plurality of fixed heater
strips disposed above and below the path of the folded web to
melt glue sandwiched between folds. The form set then
proceeds through a pair of rollers having elastomeric O-rings
aligned to apply pressure to areas of melted glue. Other
methods are practiced for heat-sealing sheets and webs into
other laminate structures, including the use of hot air blasts
to soften adhesives on sheets as they pass through pressure
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STD 302 PA 2-
rollers, and the winding of a plurality of webs against a
heated drum to produce multi-ply webbing.
Problems remain, however, in heat-sealing sheet
forms into form sets. In parti~ular, shingling of the form
sheets may cause moisture to be driven off unevenly, as the
individual sheets are both partially shielded from and
-~ partially exposed to heated surfaces. The sheets are thus
- stressed by heating, and wrinXling and curling of the sheets
. may result. Additionally, the form sets may develop ~ "C"
.shape from being dried while shingled. Smudging o~ the form
sheets may occur as sheets wipe across fixed heated surfaces,
-.~ inks often being fresh, or picking..up ink residues from
--: previously sealed form sets. Moreover, surface contact
. between the moving.shingled forms and fixed heated surfaces is
15-s not an efficient thermal transfer arrangement, so that longer
. residence times near the heated surfaces are required to melt
the adhesives.
-~. Accordingly, the need remains for further
development of suitable heat-sealing methods and apparatuses
for producing form sets for business and commercial
applications.
Summary of the Invention
This need is satisfied by the present invention
wherein opposing surfaces of firs~-and second sealing belts
- provide both heat and pressure to seal form sheets into form
- - sets, while conveying the form sheets from infeed to outfeed
of the sealing apparatus.
~isposed on rollers in a supporting base, opposing
first and second sealing belts are rotatably dr.iven in
opposits directions by means for driving. Opposing surfaces
of the first and second sealing belts, moving in the same
direction, are brought into close proximity and aligned in
generally parallel planes to define a gap through which form
sheets may be conveyed. Means for heating the first and
second sealing belts, first and second heated platens,
respectively, are posit.ioned on the opposite sides of the
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STD 302 PA -3-
sealing belts from the opposing surfaces, and contact the
inner surfaces of the sealing belts. The sealing belts slide
over their respective heated platens as they rotate,
presenting an evenly heated surface to-the form sheets. Form
sheets are separated and registered prior to entering the
sealing apparatus and pass therethrough in unshingled form.
- The form sheets are, thus, sealed with even heat, reducing
stress on the paper, eliminating wrinkling and curling, and
avoiding formation of a "C" shape, such as results from
shingling.
Because the opposing sealing belt surfaces move
-~ together, no relative motion exists between them. Attendant
problems with form sheet alignment and smudging are obviated,
and heat transfer ~from-~he opposing surfaces to the form
'5 - sheets is enhanced by continuous intimate contact over the
- entire available surface area of the form sheets. Finally,
- means for adjusting separation between opposing se~ling belt
- surfaces-enable the sealing belts O:e the present invention to
further apply pressure uniformly across the form sheets to
enhance heat transfer and sealing.
The sealing belts of the present invention are
comprised of rubber, preferably silicone rubber, laminated on
a strip of fabric material, preferably fiberglass, joined to
form an endless loop. The rubber surface forms the outer,
opposing surfaces of the sealing belts while the fiberglass-
material comprises the inner surfaces. The frictional rubber
surfaces-facilitate control of form sheets placed thereon. In
addition, silicone rubber, in particular, has good release
characteristics which make cleaning dirt, ink and adhesives
from the surface easy. In operation, the resilient rubber
surfaces accommodate some variation in the thickness of form
sheets, as well as some variation in the number of form sheets
in a form set, without requiring adjustment of the gap
separating opposing sealing belt surfaces.
The fabric material on the inner surface of the
sealing belts, preferably fiberglass cloth or another carrier
having similar properties such as Nomex, contacts rollers
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STD 302 PA -~-
which support and rotatably drive the sealing belts. Due to
iks low coefficient of friction, fiberglass is preferred as it
slides smoothly over the heated platens, and facilitates
transverse sliding of the sealing belts on the rollers to
correct tracking during operation.
Because of the improved heat transfer
characteristics of the present invention, the sealing helts
may be rotated at higher speeds than cut sheet sealing devices
in the prior art, increasing throughput and reducing residence
time of sheets in the sealing apparatus. Since the sealing
belts operate at rates consistent with the infeed rate of form
sheets, no abrupt change in speed is encountered as form
sheets enter the sealing apparatus, avoiding stubbing and
misalignment of form sheets which might otherwise be raused
thereby.
- The sealing apparatus further preferably includes
control-and adjustment elements, such as dynamic guide discs,
; to prevent the sealing belts from wandering during operation,
and trac~ing screws to adjust the rollers and align the
sealing belts to track properly. Means for adjusting the
separation between opposing surfaces o~ the sealing belts
preferably include a plurality of jasking screws which permit
control of the sealing pressure imposed on the form sheets as
they advance through the sealing apparatus, also making
--25 possible asymmetric loading to increase pressure at the
outfeed end of the sealing belts to enhance sealing.
-- Temperature sensors and controllers are preferably added to
control the temperature of the heated platens.
Finally, the sealing apparatus may also include an
infeed conveyor, outfeed conveyor and a further stacking
device, as well as related components such as hold-down
rollers-to prevent form sheets from separating as they advance
on the conveyors. The conveyors may be driven by
interconnection with the means for driving the sealing belts.
An outfeed conveyor is preferably disposed in a plane parallel
to but below the point of outfeed from the sealing apparatus.
So disposed, operation of the outfeed conveyor at a speed less
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STD 302 PA -5-
than that of the sealing belts permits sealed form sets to be
shingled as they fall onto the outfeed conveyor. Shingling of
sealed forms on the outfeed conveyor facilitates stacking the
- forms on a simple stacking support, such as a stacker bar or --
rack, on a descending stacking table, or other known devices. -
Accordingly, an object of the present invention is
- to reduce the-stress, wrinkling and curling of form sheets.
It is a-further object of the present invention to eliminate
other drawbacks caused by shingling form sheets during drying,
such as C-shapes induced in form sets. Other objects of the
present invention are to eliminate~drag induced between moving
forms and fixed surfaces,-and to avoid smudging form surfaces.
Brief Description of the Drawings
Fig. l is a schematic elevational view of the
sealing apparatus of the present lnvention.
Fig. 2 is a partial perspective view of the sealing
apparatus of the present invention.
Fig. 3 is an enlarged elevational view of the
sealing apparatus of the present invention.
Fig. 4 is a perspective view of the sealing
apparatus of the present invention.
Detailed Description of the Preferred Embodiment
Referring to Fig. l, in accordance with the present
invention, sealing apparatus l0 is comprised of a base 12 in
which first and second rotatable sealing belts 14, 16 are
heated and driven to convey and seal form sheets 18 into form
sets 20. As shown in Figs. l through 3, first and second
sealing belts 14, 16 are aligned in opposing relationship in
generally parallel planes, and rotatably driven in opposite
directions on first and second roller assemblies 22, 24,
respectively. First and second roller asseT~lies 22, 24 are
connected to drive motor 26 by means for transmitting rotary
power 28.
As best shown in Fig. 3, means for heating sealing
belts 14, 16 are preferably first and second hea~ed platens
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STD 302 PA -6-
30, 32, respectively, which lie beneath opposing surfaces 34,
36 of sealing belts 14, 16, respectively. Heated platens 30,
32 contact the inner surfaces of sealing belts 14, 16 as they
rotate, generally uniformly heating the sealing belts.
Although sealing belts 14, 16 rotate in opposite directions,
opposing surfaces 34, 36 move in concert so that substantially
no relative motion exists between opposing surfaces 34, 36
while form sets 18 are conveyed thereon.
-Sealing belts 14, 16 are preferably comprised of
silicone rubber laminated on fiberglass cloth fabric, such as
those available from Belting Industries, Inc., Kenilworth, -
N.J. Other materials having similar properties may, however,
- also--be used. The ~rubber surface serves as the outer surface
of sealing belts 1~, 16, while the fiberglass cloth serves as
the inner surface. The frictional-rubber outer surface-is
well suited to control form sheets 18 thereon, while the
fiberglass inner surface advantageously slides easily in
contact across heated platens 30, 32. While the resilient
nature of the rubber outer surface accommodates some variation
in the thickness and number of form sheets 18, means for
adjusting the separation or gap between opposing surfaces 34,
36 permits wide variation in form sheets thicXness and number.
Preferably, means for adjusting separation between opposing
surfaces 34, 36 includes four spring-loaded jackscrews 38
conne~ted to first roller assembly 22, as shown in Figs. 2 and
3. Jackscrews 38 permit application of uniform or,
- preferably, asymmetric and increasing sealing pressure--to form
sheets 18 as they advance through sealing apparatus 10.
As shown in Figs. 2 and 3, first and second roller
assemblies 22, 24 are each comprised of at least two rollers
disposed in first and second subframes 42, 44 which attach to
base 12. Use of subframes 42, 44 is preferred to facilitate
complete removal of roller assemblies 22, 24 for replacement
of sealing belts 14, 16. The at least two rollers of first
and second roller assemblies 22, 24 include first and second
drive rollers 46, 50 and, preferably, first and second idle
rollers 48, 52, respectively. As shown in Fig. l, second
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STD 302 PA -7-
drive roller 50 is connected, as known in the art, to means
for transmitting power 28, including intermeshing first and
second gears 54, 56 conveying rotary motion to first drive
roller 46 from second drive roller 50. Links 40 interconnect
~irst and second subframes 22, 24, and are also preferred to
permit separation of opposing surfaces 34, 36 and access to
sealing belts 14, 16 for cleaning and inspection. Draw
latches 41, best shown in Fig. 2, assist in maintaining first
and second roller assemblies 22, 24 in opposing relationship.
-- First and second subframes 42, 44, shown in Figs. 2
and 3, preferably include tracking screws 58 disposed--at both
ends of first and second idle rollers 48, 52, for adjusting
the axes of rotation thereof. Such adjustment is desirable to
compensate for variations in the diameter of sealing belts 14,
15- 16 across their width, and to urge them to remain in position
on-rollers 46, 48 and 50, 52, respectively. Uncompensated,
such variations in sealing-belt-diameter typically cause
sealing belts 14, 16 to track to one side or another.
Tracking screws 58 further permit adjustment of sealing belt
tension.
First and second subframes 42, 44 further preferably
includa dynamic edge guides 60, freely~rotatable on rods 62.
Shown best in Fig. 2, dynamic edge guides 60 are positioned
along the periphery of first and second sealing belts 14, 16
near idle rollers 48, 52 to prevent first and second sealing
bel-ts 14, 16 from wandering by urging their return to desired
tracking posi~ions. Such wandering could otherwise be
occasioned by expansion of sealing belts 14, 16 during warm-
up. In operation, rotation of dynamic edge guides 60 by
frictional contact with the periphery of sealing belts 14, 16
causes less wear on the sealing belts than would fixed guides,
while the smooth fiberglass inner surface of sealing belts 14,
16 facilitates lateral positioning of the sealing belts urged
by the dynamic edge guides 60. As shown in Figs. 1 and 2,
dynamic edge guides 60 are further disposed along the outer
loop of sealing belts 14, 16 because of space considerations
and because reduced belt ten~sion in the outer loops is
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STD 302 PA -8-
believed to improve -the effectiveness of dynamic edge guides
60.
Additional control and adjustment elements are
preferably included in sealing apparatus 10. In particular,
means for controlling the temperature of heated platens 30,
32, such as a bimetal thermal switch and relay (not shown) as
known in the art, may be included to control the temperature
of heated platens, preferably between 295-305 degrees
Fanrenheit (F). This protects heated platens 30, 32 from
10--- delamination of heating coils applied thereto or other damage.
Such heated platens are made of aluminum and have hard
- anodized surfaces to prevent oxidation. So heated, belts 14,
- 16 may rotate unloaded at a temperature of substantially 310
degrees F, and ra~ge generally from 260-310 degrees F when
15- loaded with form sheets 18.
As shown in Fig. 1, means for transmitting power
- includes belts, pulleys, chains and sprockets connected to
- axles as known in -the art. Drive motor 26 is an electric
motor having a rotary power take-off, as known in the art.
Shown in Figs. 1 and 4 are infeed conveyor 62 and
outfeed conveyor 82 disposed in base. 12. Infeed conveyor 62
and outfeed conveyor 82 are preferred in sealing apparatus 10
to efficiently feed and receive form sheets 18 and sealed form
sets 20, respectively. Infeed conveyor 62 is comprised of a
plurality of infeed belts 64 disposed on two or more infeed
rollers 66, 68 rotatably disposed in base 12 as known in the
- art. Means for driving the infeed conveyor 62 preferably
comprises means for connecting roller 66 to the means for
transmitting rotary power 28, such as a belt, pulley, chain
and sprocket connection as known in the art. Infeed conveyor
62 further includes an infeed hold-down roller assembly 72 to
keep individual form sheets 18 from separating as they advance
toward the infeed of sealing belts 14, 16. Infeed hold-down
roller assembly is comprised of a plurality of rollers 74
freely rotatably attached to arms 76 which are freely
rotatably on hold-down rod 78 extending above and across the
surface of infeed conveyor 62. Rollers 74 ride over the
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STD 302 PA -9-
surface of infeed conveyor 62 and form sheets 18, rotating by
frictional contact therewith. The surface of infeed conveyor
62 is disposed on substantially the same plane as second
sealing surface 36. A short fixed table section 80 spans the
gap between those surfaces.
- Outfeed conveyor 82 is comprised of a plurality of
- outfee~ belts 84 disposed on two or more outfeed rollers 86,
88 rotatably disposed in base 12 as known in the art. Means
- for driving 90 outfeed conveyor ~2 preferably comprises means
for connecting roller-86 to means for transmitting rotary
- power 28, such as a belt, pulley, chain and sprocket
- connection as known in-the art. Outfeed conveyor 82 further
includes- an outfeed hold-down roller assembly 92 to keep form
sets 20 from slidi~ng as they advance in shingled form for
15- stacking. Outfeed hold-down roller assembly 92 is also
comprised of a plurality of rollers 7-4 freely rotatably
attached to arms 76 which are freely-rotatably on hold-down
rod 94.- Hold-down rod 94 extends above and across the surface
of outfeed conveyor 82 and may be acljustably positioned
therealong in slots in support brackets 96. The surface of
- putfeed conveyor 82 is disposed below the outfeed point of
-sealin~ belts 14, 1~, as seen in Fig. 1. Outfeed conveyor 82
is operated at a slower speed than sealing belts 14, 16 so
that sealed form sets outfed therefrom align in shingled
~ashion as they arrive on outfeed conveyor ~32. Shingling at
~his-stage facilitates stacking. Means for stacking 98, such
~s a simple stacking bar or rack, shown in Fig. l,-or a
descending stacker as known in the art (not shown), may be
used.
Sealing belts 14, 16 are typically operated at
approximately 115 feet per minute (fpm). Infeed conveyor 62
is typically operated a few feet per minute less, for example
at approximately 113 fpm, to prevent stubbing and misalignment
of entering form sheets 18. Form sheets 18 may be registered
and aligned for placement on infeed conveyor 62 by various
means registering 100 known in the art. Where continuous webs
are folded and burst prior to placement on infeed conveyor 62,
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STD 302 PA -10-
form sheets 18 which result may have a folded edge aligned
longitudinally or transversely to the direction of form
motion. Typically, means for registering 100, such as a
bursting apparatus, operates at slower speeds than infeed
conveyor 62, for example 90 fpm, to provide and enhance
separation between adjacent form sheets 18 on sealing belts
14, 16. Outfeed conveyor 82 is typically operated at
substantially slower speeds, for example 30 fpm, to permit
shingling of sealed form sets 20.
Various other details of construction and component
materials used are typical and known in the art.
- - While certain representative embodiments and details
have been shown for purposes of illustrating the invention, it
will be apparent to those skilled in the art that various
-changes- in the apparatus disclosed herein may be made without
departing from the scope of the invention, which is defined in
the appended claims.
