Laminating apparatus wherein sheets to be bonded form heating chamber

A laminating machine for laminating outer sheets one on each side of an inner sheet, in which all three sheets are moved along in alignment, one spaced above the other, with their edges enclosed by adjustable side covers. The side covers together with the top and bottom sheets form a chamber. Contact adhesive is sprayed on the sheets at the entrance to the chamber. Heater bars span the chamber near the entrance to dry the adhesive. A suction box at the other end of the chamber draws air through the entrance, over the adhesive and heater bars, and then exhausts the solvent laden air. Beyond the suction box, pinch rollers compress the three sheets together to laminate them.

Reference is first made to FIG. 1, which shows a laminating machine 
generally indicated at 10, having a fixed frame 12. Mounted on the frame 
12 is an upper supply roll 14 which dispenses an upper aluminum sheet 16, 
and a lower supply roll 18 which dispenses a lower aluminum sheet 20. The 
upper aluminum sheet 16 is dispensed rearwardly. over an upper idler 
roller 22 and is then directed forwardly along a direction of travel 
indicated by arrow 24. The lower aluminum sheet 20 travels rearwardly over 
a lower idler roller 25 and then travels forwardly again in the direction 
of arrow 24. The dispensing of the upper and lower aluminum sheets is also 
shown in FIG. 2. 
As also shown in FIGS. 1 and 2, a foam inner core or sheet 28 is fed over a 
guide lip 30 fastened to the frame 12 and is then fed between the upper 
and lower aluminum sheets 16, 20. The foam sheet 28 may be of any suitable 
material, e.g. polyvinyl chloride foam, and is fed by any desired means, 
either manually or by a separate dispenser. The supply rolls 14, 18 and 
the foam sheet 28 are located so that the side edges of all three sheets 
(which are of the same width) are aligned one above the other. 
The frame 12 includes fixed upper and lower longitudinal members 32a, 32b, 
34a, 34b. The upper and lower members 32a, 34a and 32b, 34b are held 
together by vertical members 36a, 36b and by upper and lower laterally 
extending cross bars 38, 40. The frame 12 thus has an open box-like 
appearance, as shown. 
The foam inner sheet 28 is supported on the upper cross bars 38 by rollers 
42 mounted thereon. The rollers are typically formed of the low friction 
plastic sold under the trade mark TEFLON. Side guides 43 adjustably 
mounted on the cross bars 38 guide the edges of the foam sheet 28 as such 
sheet is fed toward the supply rolls 14, 18. 
The foam inner sheet 28 is further supported and is also transported by a 
pair of endless steel bands shown at 44a, 44b in FIGS. 1 and 3. Each band 
44a, 44b travels longitudinally nearly the entire length of the frame, and 
extends around pulleys 46a, 48a, or 46b, 48b at each end of the machine. 
The bands 44a, 44b are supported and guided by notches 50 (see FIGS. 4 and 
5) formed in the upper cross bars 38. As shown in FIG. 3, the outer 
pulleys 46a, 46b have shafts 52, 52b depending therefrom, containing at 
their ends bevelled gears 54a, 54b which mesh with corresponding bevelled 
gears 56a, 56b on a cross shaft 58. The cross shaft 58 is driven by a 
pulley 60 from a gear box 62 and electric motor 64. 
On their return travel, the bands 44a, 44b are supported and guided by 
notches 66 (FIG. 5) cut in support brackets 68 mounted on and projecting 
outwardly from the upper frame members 32a, 32b. 
With reference now to FIGS. 1, 6 and 7, it will be seen that the portion of 
the upper frame located downstream of the supply rolls 14, 18 is of 
special construction. Specifically, mounted above each upper frame member 
32a, 32b is a second upper frame member 70a, 70b. The frame members 70a, 
70b are supported on frame members 32a, 32b by spacer blocks 72a, 72b 
(FIG. 6) and extend from the supply rolls 14, 18 to a suction box 74 (to 
be described). The second upper frame members 70a, 70b are for a purpose 
which will be indicated shortly. 
The cross bars 38 located between the supply rolls 14, 18 and the suction 
box 74 carry two side covers 76a, 76b. The side covers 76a, 76b have 
openings 78a, 78b therein so that they fit snugly on but are slidable 
laterally on cross bars 38. 
Each side cover 76a, 76b includes an upper separate L-shaped section 80a, 
80b having a side flange 82a, 82b which overlies the side of its side 
cover 76a, 76b, and having an inturned top flange 84a, 84b which overlies 
and is spaced above an inturned top flange 86a, 86b of the side cover 76a, 
76b. The two top flanges 84a, 86b and 84b, 86b are connected together by 
bolts 88a, 88b welded to flanges 86a, 86b and extending upwardly through 
flanges 84a, 84b and secured by nuts 90a, 90b. 
The side covers 76a, 76b support lower sliding cross bars 92 which extend 
through relatively snugly fitting openings 94 in the covers and 
essentially abut (with a slight clearance) the frame members 32a, 32b. The 
side covers 76a, 76b also support upper sliding cross bars 96 which extend 
through relatively snugly fitting openings 98 in side flanges 82a, 82b and 
through vertically enlarged openings 100 in the sides of side covers 76a, 
76b. The upper sliding cross bars 96 abut (with a slight clearance) the 
second upper frame members 70a, 70b. 
The arrangement described allows the side covers 76a, 76b to be moved 
laterally inwardly or outwardly dependent on the width of the aluminum and 
foam sheets 16, 20, 28 being laminated. The "sliding" upper or lower cross 
bars themselves do not move laterally, since they are constrained by the 
frame members 32a, 32b, 70a, 70b. In addition the height of the upper 
sliding cross bar 96 can be adjusted by turning the bolts 88a, 88b 
dependent on the thickness of the foam sheet 28. In use the side covers 
76a, 76b are adjusted so that the space between them is very slightly 
greater than the width of the sheets being laminated. Threaded cross-bars 
(not shown) may also be inserted between the covers 76a, 76b at their tops 
and bottoms and extending to the frame members 32a, 32b, 70a, 70b, to hold 
the covers rigidly with a small clearance from the edges of the sheets 
being laminated. 
The upper aluminum sheet 16 is supported (see FIG. 7) by thin plastic 
inserts 102 (e.g. made of the plastic known under the trade mark TEFLON) 
inserted in slots in the upper sliding cross bar 96. The lower aluminum 
sheet 20 is similarly supported by similar thin plastic inserts 104 in the 
lower sliding cross bar 92. 
It will be seen that the upper and lower aluminum sheets 16, 20 together 
with the side covers 76a, 76b form an enclosed chamber within which the 
foam sheet 28 travels. At the entrance to the chamber, as shown in FIGS. 
1, 2 and 9, a suitable adhesive (such as urethane contact adhesive) is 
sprayed on the inner surfaces of both the aluminum sheets 16, 20 and on 
both surfaces of the foam sheet 28 by a pair of reciprocating spray guns 
106a, 106b. Each spray gun 106a, 106b is mounted on a traverse frame 108a, 
108b. The traverse frames 108a, 108b are guided for reciprocating movement 
across the machine by pairs of guide rods 110a, 110b extending between the 
vertical frame members 36a, 36b. Each traverse frame member is connected 
on each side thereof to an endless chain 112a, 112b (FIG. 9) by means of 
lugs 114 and nuts 115 (FIG. 10). 
The chains 112a, 112b travel around opposed sprockets 116a, 116b on each 
side of the machine 10. The sprockets 116a are connected together by a rod 
118 containing sprockets 120 around which pass a pair of vertically 
extending endless chains 122. The chains 122 pass around lower sprockets 
124 and are driven in a reciprocating vertical movement by a pneumatic 
drive cylinder 126. The cylinder 126 has its piston rod 128 connected to a 
cross bar 130 which is connected at each end to the chains 122. The air 
for the drive cylinder 126 and also for the spray guns 106a, 106b is 
supplied to a valve 132 which is controlled by a vertically oriented 
operating rod 134 guided by a bracket 136 mounted on a vertical frame 
member 36a. The rod 134 contains upper and lower stops 138, 140. The drive 
cylinder cross bar 130 contains a lug 142 through which rod 134 passes, 
with coil springs 144 encircling rod 134 above and below the lug 142. 
Thus, as the drive cylinder piston rod 128 moves up and down, the springs 
144 press against the stops 138, 140 and operate the air valve 132 to 
reverse the direction of movement of the drive cylinder. The springs 138, 
140 operate as shock absorbers. This arrangement causes the adjustable 
spray guns 106a, 106b to reciprocate back and forth at about one stroke 
per second, spraying contact adhesive on the inner surfaces of the 
aluminum sheets 16, 20 and on both sides of the foam sheet 28 as 
mentioned. 
The wet adhesive on the aluminum and foam sheets is dried by heat supplied 
from a set of transverse heater bars 146 best shown in FIGS. 2 and 8. As 
shown, the heater bars 146 extend through slots 147 in the side covers 
76a, 76b but are not fixed thereto so that the side covers may be slid 
laterally with respect to the heater bars. Typically eight heater bars 146 
are used, each of about 1,000 watts capacity, to provide sufficient heat 
to evaporate the solvents used in the contact adhesive. As shown the 
heater bars 146 extend between each aluminum sheet 16, 20 and the inner 
foam sheet 28 and are located adjacent the upstream end of the chamber 
formed by the aluminum sheets and the side covers. The upper heater bars 
will, as shown, move up and down as the L-shaped sections 80a, 80b are 
moved up and down. At one side of the machine the second upper frame 
member 70a is interrupted at the location of the heater bars and replaced 
by a cover 148, to allow access to the heater bars and their terminals. 
At the downstream end of the chamber formed by aluminum sheets 16, 20 and 
side covers 76a, 76b, the suction box 74 serves to draw air into the 
upstream end or entrance of the chamber, past the heater bars 146, and 
then out through an exhaust pipe 150 (FIG. 1) The hot air flow over the 
adhesive coated surfaces dries the adhesive. A high speed blower 152 draws 
the solvent laden air from pipe 150 and expels it through a duct 154 to an 
appropriate air cleaner or solvent recovery system, or to atmosphere. When 
the sheets reach suction box 74, the contact adhesive at this location is 
now sufficiently dry that the sheets are ready to be pressed together. 
As shown in FIGS. 11 and 12, the suction box 74 includes upper and lower 
walls 156a, 156b, side walls 158a, 158b and end walls 160a, 160b. One side 
wall 158a contains a removable glass viewing panel 126 so that the 
alignment of the sheets within can be viewed by a person setting up the 
machine and for access to the inside of the suction box 74. The end walls 
160a, 160b contain openings 164a, 164b through which the sheets 16, 20, 28 
may pass, the openings being at least partly sealed by rubber flaps 166a, 
166b. The aluminum sheets 16, 20 are forced against the flaps 166a by full 
width rollers 168 which can at this point press against the inner surfaces 
of aluminum sheets 16, 20 since the contact adhesive is essentially dry at 
this portion. 
Located within the suction box 74 are several narrow laterally spaced 
support rollers 170 mounted on a cross bar (not shown) to support the foam 
sheet 28 as it travels through the suction box 74. 
The suction box 74 also includes a pair of heater bars 172a, 172b thickly 
coated with heat resistent low friction plastic such as that sold under 
the trade mark TEFLON. The plastic coating is indicated at 174a, 174b. The 
upper aluminum sheet 16 slides over and is supported by the upper heater 
bar 172a and the lower aluminum sheet 20 slides over and is guided by the 
lower heater bar 172b. The aluminum sheets and foam inner sheet then exit 
through opening 164b from the suction box and converge between a pair of 
pinch rollers 180a, 180b which will now be described. 
As shown in FIGS. 13 to 15, three pairs of opposed pinch rollers 180a, 
180b, 182a, 182b, 184a, 184b are provided. Only the central pair 182a, 
182b is powered, driven by a gearbox and motor 186 and a chain 188. This 
provides the entire drive for the aluminum sheets 16, 20 and also pulls 
the foam sheet 28 (which may be in individual sections rather than being 
continuous). The remaining pinch rollers act as idlers. 
When the laminated product to be formed is to be straight and flat, then 
the pinch rollers are all arranged in a straight line as shown in FIG. 13. 
Pressure on the central pair of driven pinch rollers 182a, 182b is 
provided as follows. Each pinch roller 182a, 182b is mounted on a shaft 
190a, 190b journalled in a block 192a, 192b. The blocks 192a, 192b are 
connected together by tongues and grooves with the corresponding blocks of 
the other pinch rollers as shown in FIG. 14. The upper central blocks 192a 
each have a vertical rod 194 threaded therein, with a crank handle 196 at 
the end of one of the rods 194. A chain 198 encircles corresponding 
sprockets 200 on the rods 194. When the crank handle 196 is turned couner 
clockwise, the rod 194 will attempt to rise, but this is prevented by a 
rubber block 202 which abuts an upper upper frame member 204 of the pinch 
rollers. Further cranking causes the pinch roller block 192a to be driven 
resiliently downwards against the compression of the rubber block 202. A 
"resilient" pressure is therefore applied to the pinch roller 182a. The 
pressure is uniform at each end of the pinch roller 182a because of the 
chain 198. Similar roller blocks (not shown) may be used for the other 
pinch rollers. 
If it is desired to produce a curved laminated product, then a cylinder 204 
(FIG. 13) is actuated to drive arm 206 clockwise about shaft 208. Arm 206 
contacts a rod 210 projecting from the bottom of the end pinch roller 
mounting block 212b, forcing this block slightly upwardly to move the end 
lower pinch roller 184b to the position shown in FIG. 15. Nuts 214 are 
first loosened to allow this process. At the same time, bolt 216 is 
operated to lift the upper end pinch roller 184a out of the way. The 
curved arrangement of the pinch rollers shown in FIG. 15 then produces a 
continuously curved laminated sheet (which of course is cut into discrete 
lengths by any appropriate cutting means). There is a duplicate of 
cylinder arm 206 (not shown) at the far side of the machine 10, also 
mounted on shaft 208 to turn with arm 206. 
If the polyvinyl chloride foam core sheet 28 is supplied from a roll, then 
if desired, three horizontally aligned sets of steel pinch rollers (not 
shown) heated to a suitable temperature may be used to remove any memory 
from the core sheet 28 and to ensure that sheet 28 is flat, before sheet 
28 enters between the outer sheets 16, 20.