Apparatus and method for the manufacture of molded packings

Open molds for forming molded packings are moved sequentially to a series of work stations. The work stations include a preparation station for preparing the molds with a separator sheet or other release agent and a clamping station for covering the molds to contain foam material within the molds during cure. The foam material is dispensed into the molds as the molds are moved from the preparation station to the clamping station. The molds may be inverted as they are moved from the clamping station to an ejection station such that removal of the molded packings is facilitated by gravity. The sequence and duration of the various operations are controlled to provide automatic manufacture of the molded packings. A unique system for delivering a thin sheet to a molding machine or to other types of sheet processing machines is also disclosed.

BACKGROUND OF THE INVENTION 
The present invention relates to the manufacture of molded packings. More 
particularly, the invention is directed to an apparatus and method for 
molding packings of low-density foam or similar material for use in 
packaging various articles for shipment. 
In the shipment of typewriters, video displays, computer terminal modules, 
and the like, the article must be packaged so as to protect against 
physical shock and vibration during handling. One technique involves the 
use of preformed pads or cushions that are specifically shaped to fill a 
portion of the space between the article and the container in which it is 
shipped. Typically, such pads are molded of cellular polystyrene and are 
placed at the ends of the article and/or above and below the article. 
Such premolded pads provide only limited protection is too stiff to absorb 
the energy of minor shock or vibration and, since the polystyrene has 
almost no memory, there is little protection against a subsequent shock 
after the cellular structure has been crushed. Furthermore, the high 
temperatures and pressures required for the molding of the pads 
necessitate machined steel molds. Because of the high tooling costs, such 
pads are not used for packaging many low production items, and, generally, 
the pads must be centrally manufactured, stored, and transported to each 
packaging site. 
Another packing technique involves a foam-in-place process wherein the 
article is placed in a container and a protective separator sheet is 
tucked around the article. Low-density urethane foam or similar resilient 
material is then poured from hand-held dispensing guns into the space 
between the sheet and the container to firmly support the article. The 
foam-in-place technique may cause undesirable stress upon sensitive 
portions of the article, resulting in damage, and the foam-in-place 
technique does not facilitate the formation of a supporting low-density 
foam packing below the article. 
Accordingly, a related technique involves the molding of a urethane packing 
within the shipping container before the article is placed therein for 
shipment. This technique may use a mold form, generally representative of 
the article and any desired voids, mounted upon a platform. A separator 
sheet of thin plastic is placed over the mold form and drawn against the 
mold form by vacuum. A shipping container such as a corrugated carton with 
opened flaps is then placed over the mold form, and foam is injected into 
the container to form a molded packing directly in the container in which 
the article is to be shipped. 
These techniques using low-density urethane foam packaging provide improved 
energy absortion over that of cellular polystyrene pads, and the plastic 
sheet provides added protection against abrasion. However, the many manual 
operations required and the inconvenience of molding directly in the 
shipping container make these techniques poorly suited to many 
applications. And, even when a molded packing is formed directly in the 
container below the article, the foam-in-place above the article may 
result in undesirable stress on sensitive portions of the article or 
inadequate support of the article. There is no convenient means to hold 
the separator sheet away from sensitive portions of the article and 
tightly against desired support surfaces during cure. 
Accordingly, a need exists for a means of efficiently manufacturing molded 
packings, of low-density urethane foam or other resilient low-density 
material, that can be inserted between the article and the shipping 
container during packaging. Such molded packings would have the 
convenience of cellular polystyrene pads plus the superior energy 
absorption and abrasion protection of foam-in-place low-density urethane 
packing. In addition, the configuration of such molded packings should be 
controllable so as to accurately provide desired voids at sensitive 
portions of the article and an interference fit at desired support 
portions to firmly hold the article in place. 
Conventional molding machines, as used in the manufacture of cellular 
polystyrene pads, are not suitable for molding packings of low-density 
urethane foam or similar material. The low-density foam lacks sufficient 
integrity for molding without a separator sheet of plastic or other 
material at the surface of the foam, and conventional molding machines 
cannot accommodate the sheet material. A particular problem is the 
difficulty of delivering a large separator sheet of thin material to a 
molding machine such that it can be efficiently tucked into the corners of 
a mold. Hand-held dispensing guns, as used in the formation of 
foam-in-place urethane packings described above, do not ensure a 
consistent, accurate flow of foam material. 
It is therefore an object of the present invention to provide an apparatus 
and method for manufacturing molded packings of low-density urethane foam, 
or other resilient low-density material, for insertion between an article 
and a shipping container. It is a related object of the present invention 
to provide a means for manufacturing such molded packings accurately and 
efficiently without the need for expensive machined steel molds. It is a 
further object of the present invention to provide a means for 
manufacturing such molded packings that requires a minimum of human 
intervention and that is suited to a limited floor space. It is still a 
further object of the present invention to provide a sheet delivery 
apparatus for delivering a sheet of thin material to a molding apparatus 
or other sheet processing machine. 
SUMMARY OF THE INVENTION 
The present invention is directed to both an apparatus and method for use 
in the manufacture of molded packings. 
According to one aspect of this invention, a plurality of open molds are 
movable sequentially to a series of work stations. The work stations 
include a preparation station for preparing the molds with a release 
agent, a clamping station for closing the molds to contain a foam material 
within the molds during cure, and an ejection station for ejecting 
completed molded packings from the molds. Means for dispensing the foam 
material into the molds is provided between the preparation station and 
the clamping station. A conveyor or other moving means moves the molds 
from the preparation station past the dispensing means to the clamping 
station, from the clamping station to the ejection station, and from the 
ejection station back to the preparation station. 
Preferably, the apparatus of this invention includes means for delivering a 
separator sheet to the preparation station and for inserting the separator 
sheet into the molds to serve as the release agent. Vacuum means may be 
employed to hold the separator sheet in position within the molds. The 
clamping station may include a cover prepared with a release agent and 
means for selectively clamping the cover against the molds to contain the 
foam material during cure. The dispensing means may include individually 
controllable dispensing guns disposed above the path of the molds to 
dispense the foam material in a predetermined pattern. The moving means 
may comprise a continuous loop conveyor having the molds equally spaced 
thereon. 
According to another aspect of the present invention, an apparatus for 
delivering a sheet of thin material from a supply roll to a molding 
machine or other sheet processing machine is provided. The apparatus 
unrolls a portion of the material from a leading edge and stores a length 
of the material as it is unrolled. The leading edge of the material is 
held by rollers or other means and is advanced toward the processing 
machine. Tracks adjacent the processing machine are movable to a closed 
position to grip the advanced material and are rollable to draw a 
predetermined length of the stored material. A cutting device cuts the 
predetermined length from the supply roll to form the sheet. 
Preferably, the apparatus for delivering the sheet of thin material 
includes rollers for gripping the leading edge of the material to advance 
the leading edge toward the sheet processing machine. The apparatus may 
include other rollers biased to form at least one loop of the material to 
store the unrolled material and may include sensing means to control the 
length of material unrolled from the supply roll and stored in preparation 
for delivering the sheet. This apparatus is particularly useful in 
delivering large, easily tearable sheets, such as those required as 
separator sheets in molding low-density urethane or similar material. 
According to another aspect of the present invention, a series of steps 
comprising a method for manufacturing molded packings is provided. Open 
molds are moved sequentially to a series of work stations in a continuous 
loop. The molds are prepared with a separator sheet or other release agent 
at a first work station, and a foam material is dispensed into the molds 
while the molds are moving from the first work station to a second work 
station. The molds are closed at the second work station to contain the 
foam material during cure and are inverted as they are moved to a third 
work station. At the third work station, the completed molded packings are 
ejected from the molds by pushing on the molded packings from within the 
molds. 
It is a particular feature of the present invention that the molds can be 
made inexpensively and can be easily installed and removed from the 
apparatus to facilitate the manufacture of molded packings having various 
configurations. And, a resilient plug may be used to insert the separator 
sheet into the molds to permit two or more molds to be installed 
simultaneously, thereby allowing top and bottom molded packings, for 
example, to be manufactured alternately. The apparatus requires little 
floor space and can be conveniently placed adjacent an assembly line of an 
article to be packaged such that the molded packings need not be stored 
and transported from a centralized molding machine.

DESCRIPTION OF THE PREFERRED EMBODIMENT 
Turning now to the drawings, FIGS. 1 and 2 show in side elevation and plan 
view an apparatus for making molded packings in accordance with this 
invention. As shown in FIG. 1, the apparatus includes suitable means such 
as a continuous conveyor, indicated generally by the numeral 10, for 
moving a plurality of open mold boxes, indicated generally by the numeral 
12, between a series of work stations. The mold boxes 12 are advanced 
sequentially by the conveyor 10 from a preparation station 14, past a 
dispensing station 16, to a clamping station 18, to an ejection station 
20, and back to the preparation station 14. 
Although alternative conveyor configurations may be used with similar 
effect, the conveyor 10 may include continuous belts or chains 22, 24 
engaged by sprockets 26, 28, 30, 32. The sprockets are joined by axles 34, 
36 to ensure movement in unison. Each of the mold boxes 12 is releasably 
mounted upon the chains 22, 24 by four pivotal mountings 38. The mountings 
38 are centered sufficiently to permit the mold boxes to follow the 
circumference of the sprockets as indicated by the mold boxes 40, 41 shown 
in phantom in FIGS. 1 and 2. A drive motor 42 or other suitable drive 
means is selectively engageable to drive the chains 22, 24 in a 
counterclockwise loop, as shown in FIG. 1. Transmission means such as, for 
example, a belt or chain drive 44 may be used to transmit power to the 
sprocket 30, as shown. 
As best shown in FIGS. 3-5, upper tracks 46, 48 and lower tracks 50, 52 
are, preferably, placed below the chains 22, 24 to maintain alignment of 
the chains 22, 24, and support the weight of the mold boxes 12. The upper 
and lower tracks can be fixed to side panels 54, 56 upon which the axles 
34, 36 are journaled. The side panels 54, 56 are supported by vertical 
members 58, 60, 62, 64 which are flange-mounted to the floor 42. Vertical 
members 58, 60 are joined by a horizontal member 66, as shown. A sensor, 
not shown, initiates an emergency shutdown if the conveyor 10 becomes 
jammed. 
Preferably, the preparation station 14, best shown in FIG. 3, employs a 
movable plug 70 to push a separator sheet 71 of polyethylene film into 
position within a first mold box 72. The configuration of the plug 70 is 
generally the negative of that of an internal surface or mold cavity 74 of 
the mold box 72 to ensure that the separator sheet 71 is tucked firmly 
into the corners of the mold cavity. The plug 70 may be made of any 
suitable material and may be conveniently molded of foam. It should be 
understood that alternative release agents may be used in place of the 
separator sheet 71 shown. 
A particular feature of the preferred embodiment is that more than one 
configuration of molded packing can be produced on a single apparatus. 
Applicant has found that by making the plug 70 of a resilient high density 
foam such as, for example, urethane foam having a density of 2.0 pounds 
per cubic foot, the plug 70 can conform to a variety of shapes. The mold 
boxes 12 may then have different configurations of the cavity 74 
corresponding for example, to the upper and lower contours of the article 
to be packed such that upper and lower molded packings can be produced 
alternately. Mold boxes with four different configurations of the cavity 
74 may be used simultaneously. 
A unique poly-feed system, indicated generally by the numeral 76, may be 
used to automatically deliver the separator sheet 71 to the preparation 
station 14; however, other delivery systems could be employed. The 
poly-feed system 76 includes a lower end assembly, indicated generally by 
the numeral 78, having two long rollers 80 and 82 positioned horizontally 
to form a bed for supporting a large roll 84 of the separator sheet 71 
having a leading edge. A drive motor 88 rotates the roller 80 to unroll 
the leading edge of the separator sheet 71 when electrically actuated by 
the upward movement of a spring-mounted dancer 90 that holds a loop 92 of 
the separator sheet 71. 
The dancer 90 moves upward and actuates a microswitch 94 when the poly-feed 
system 76 delivers the loop 92 to the preparation station 14, as described 
below. After feeding of the loop 92, the drive motor 88 unrolls the roll 
84 until the dancer 90 pulls down another loop of the separator sheet 71 
in preparation for another delivery cycle. Preferably, a sensor, not 
shown, indicates when the amount of separator sheet 71 on the roll 84 is 
low. A movable upper assembly, indicated generally by the numeral 96, 
includes free-wheeling rollers 98 and 100 that cooperate with the dancer 
90 to form the loop 92. 
As best shown in FIGS. 1 and 2, multiple upper rollers 102, 104, 106 engage 
lower rollers 110, 112, 114 to hold the separator sheet 71 firmly in 
position therebetween. Preferably, the rollers are linked together to 
ensure movement in unison and to facilitate loading of the separator sheet 
71. The upper and lower rollers are journaled upon upper and lower frame 
members 116 and 118, respectively, of the upper assembly 96. The rollers 
may include a resilient or high-friction surface to provide improved 
gripping of the separator sheet 71. 
One or more fluid cylinders 120 effect horizontal movement of the upper 
assembly 96 as a unit toward the preparation station 14. This horizontal 
movement of the upper assembly 96 places the separator sheet 71 between 
moving upper tracks or grip belts 122, 124 and lower tracks or grips belts 
126, 128 of the preparation station 14. Openings 127 and 129, provided 
between the upper rollers 102 and 104 and a central table portion 131, 
permit this horizontal movement. The rollers allow the separator sheet 71 
to be pulled forward toward the preparation station 14 and may be provided 
with a ratchet device to ensure that the separator sheet 71 is not pulled 
backward out of the rollers. 
The upper grip belts 122, 124, joined by axle 129, are driven clockwise by 
a motor 130, as shown in FIG. 1, which is timed to dispense the correct 
length of the separator sheet 71. Once this timer times out, the drive 
motor 130 stops, and a hot wire 132, mounted upon the frame member 116 of 
the upper assembly 96, is extended by a pair of fluid cylinders 134, 136 
so as to be forced through the separator sheet 71 to cut the sheet to 
length. The upper assembly 96 is returned to the position shown in FIGS. 1 
and 2 by the fluid cylinders 120 during delivery of the separator sheet 71 
to permit the hot wire 132 to clear the upper and lower grip belts 122, 
124, 126, 128. 
The lower grip belts 126, 128 are moveably mounted and are actuated by 
fluid cylinders 138, 140, 142, 144 between a raised position in engagement 
with the upper grip belts and a lowered position. The lowered position 
facilitates horizontal movement of the upper assembly 96 toward the 
preparation station 14 and releases the separator sheet 71. The lower grip 
belts act as followers; only the upper grip belts are driven by the motor 
130. Preferably, a resistance sensor, not shown, senses continuity of the 
hot wire 132 to indicate that the hot wire 132 is not broken. 
With the separator sheet 71 cut to length and positioned by the grip belts, 
the plug 70 is forced downward into the cavity 74 of the mold box 72. 
Simultaneously, the lower feed tracks 126, 128 are lowered by the fluid 
cylinders 138, 140, 142, 144 to free the separator sheet from the grip 
belts. As best shown in FIG. 3, movement of the plug 70 is provided by a 
fluid drive means 146 mounted on a horizontal member 147 supported from 
the vertical members 62, 64, horizontal members 148, 150, and secondary 
vertical members 154, 156. Guide rods 158, 160 ensure alignment of the 
plug 70 with the mold box 72. 
In the preferred embodiment, a vacuum tray 162 is raised by fluid cylinders 
164, 166 to abut the underside of the mold box 72 when the plug 70 bottoms 
out in the cavity 74. Alternatively, other suitable means for holding the 
separator sheet 71 could be employed. The vacuum tray 162 has a perimeter 
corresponding to that of the mold box 72 and a gasket for sealing the 
vacuum tray to the mold box. Applicant has found that a vacuum tray depth 
of 2 inches is sufficient for a typical application such as that described 
below. 
A vacuum motor 168, connected to the vacuum tray 162 by a flexible tube 
170, is energized to create a vacuum in the vacuum tray 162. The bottom of 
the mold box 72 and the cavity 74 are perforated with many small holes to 
provide air communication between the vacuum tray 162 and the surface of 
the separator sheet 71. When the separator sheet 71 is held in place by 
the vacuum, the plug 70 is retracted by the fluid power means 146, leaving 
the mold cavity 74 prepared for filling with foam material. A vacuum 
sensor, not shown, tests for a predetermined amount of vacuum in the tray 
to ensure that the separator sheet 71 is in position as a parting agent 
prior to cycling of the conveyor 10. 
When these preparation steps and the partial curing of the foam material, 
described below are completed, the conveyor 10 is actuated to move the 
first mold box 72 in a continuous motion from the preparation station 14 
to a position at the clamping station 18, indicated by that of the second 
mold box 172 in FIGS. 1 and 2. As the mold box passes under the dispensing 
station 16, a predetermined amount of polyurethane or other suitable foam 
material is dispensed into the mold cavity 74 by suitable dispensing means 
such as dispensing guns 174, 176, 178, best shown in FIG. 4. The 
dispensing guns may be conveniently fixed to the side panels 54, 56 of the 
conveyor 10 by vertical support members 180, 182 and a horizontal member 
184 therebetween. 
It is a particular feature of the preferred embodiment that gravity is 
employed to facilitate the flow of the foam material as well as the 
removal of the completed molded packings, as discussed below. The 
dispensing guns may have multiple jets per head to further provide precise 
flow of the foam material into portions of the cavity 74. Although 
provision may be made to continue the application of vacuum to the 
separator sheet 71 until the dispensing of the foam material has been 
completed, Applicant has found that such provision is unnecessary. For 
convenience, the vacuum tray is withdrawn by the fluid cylinders 164, 166 
before the mold box is moved from the preparation station 14 to the 
dispensing station 16. 
Preferably, the dispensing guns 174, 176, 178 are actuated by microswitches 
186, 188, 190, which may be conveniently mounted upon a cross-member 197, 
selectively actuated by trip plates 192, 194, 196, respectively, as the 
mold boxes pass. Although three dispensing guns are illustrated, it will 
be apparent that any number of dispensing guns may be controlled by a like 
number of microswitches to provide a predetermined flow of chemical foam 
material into the contours of the mold cavity 74. The dispensing period 
for each gun may be controlled independently by appropriate location of 
the trip plates. The same microswitches may be actuated by trip plates of 
other interchangeable mold boxes to automatically provide a different 
preprogrammed flow pattern for forming molded packings of a different 
configuration on the same apparatus. 
The apparatus of the preferred embodiment includes a purge operation to 
clean the dispensing guns 174, 176, 178 following each use. After the mold 
box 72 passes the dispensing station 16, fluid cylinders 202, 204 move a 
solvent trough 206 into position below the jets of the pour guns 174, 176, 
178 to permit flushing of the gun heads. A pump 207 circulates recycled 
and filtered solvent to the dispensing guns 174, 176, 178 by a delivery 
tube 209. A tube 208 carries the solvent from the trough 206 to a holding 
tank 210 for recycling. Preferably, a pressure sensor, not shown, is used 
to give a warning when the solvent level is low. After purging, the 
solvent trough 206 is retracted by the fluid cyclinders 202, 204 in 
preparation for the next dispensing cycle. Each dispensing gun can be 
flowed individually for testing or purging and can be solvent flushed 
manually. 
The mold box 72 is moved continuously by the conveyor 10 from the 
preparation station 14 to the clamping station 18 before coming to rest. 
The clamping station 18 includes a cover 220 which is moved downward by a 
fluid cylinder 222 into engagement with the top of the mold box 172 to 
constrain the foam material as it expands and cures. Alternatively, other 
suitable means for closing the cavity 74 could be employed. The fluid 
cylinder 222 may be conveniently mounted upon the horizontal member 66. 
The cover 220 may be flat, as shown, or may have a raised configuration to 
provide packing locations for supplementary articles or to reduce the 
amount of foam material required. 
Although other methods such as a teflon spray could be used as a parting 
agent to prevent bonding of the cover 220 to the foam, the preferred 
embodiment provides a separate sheet of a suitable material such as 
polyethylene film between the cover 220 and the mold box 172. A small roll 
224 of the separator sheet is supported upon a bed of rollers 226, 228 
which are driven by a drive motor 230 through a pully and belt or similar 
transmission means. During the operation cycle, the separator sheet 
adheres to the foam material within the cavity 74 as the cover 220 is 
raised by the fluid cylinder 222. Later, when the conveyor 10 moves the 
mold box 172 foward, the drive motor 230 feeds the separator sheet from 
the roll 224 to maintain a slack condition of the separator sheet. 
As the mold box is tipped on edge at the end of the conveyor 10, as shown 
as mold box 41 in phantom in FIG. 1, the back edge of the mold box 41 is 
levered upward, bringing the separator sheet adjacent the raised cover 
220. A pair of toggle clamps 232, 234, actuated by fluid cylinders 236, 
238, are mounted on the cover 220 adjacent the path of the separator 
sheet. At the instant the back edge of the mold box passes the clamps 232, 
234, the fluid cylinders 236, 238 are energized to pivot the fingers of 
the clamps 232, 234 under the separator sheet and hold the separator sheet 
firmly against the underside of the cover 220. 
Approximately 0.1 second after the separator sheet is clamped to the 
underside of the cover 220, a hot wire 240, movably mounted on the edge of 
the cover 220, is moved downward by a pair of fluid cylinders 242, 243 to 
cut the separator sheet. The drive motor 230 is then stopped, leaving the 
separator sheet below the cover 220 in position for closing another mold 
cavity 74. After the next mold box moves into position below the cover 220 
and the cover 220 is lowered by the fluid cylinder 222, the fingers of the 
clamps 232, 234 are opened. This permits the cover 220 to be raised while 
leaving the separator sheet adhering to the foam material after the foam 
material has become sufficiently cured. A sensor, not shown, indicates 
when the amount of separator sheet remaining on the roll 224 is low. 
During the next moving cycle, the mold box 172 moves from the clamping 
station 18 through the inclined position indicated in phantom as mold 
boxes 40, 41 to an inverted position at the ejection station 20, indicated 
as that of mold box 244. As best shown in FIG. 5, two fluid cylinders 246, 
248, conveniently fixed to a cross-bar 250 joining the vertical members 
58, 60, are energized to extend ejector members or bars 252, 254 through 
slots penetrating the mold box 244 and the cavity 74 to push the completed 
molded packing downward from the mold box 244. Due to the inverted 
position of the mold box 244, the completed molded packing falls cleanly 
from the cavity 74 by the force of gravity without the need for lifting 
means. 
Compressed air or other fluid may be expelled from the ends of the bars 
252, 254 to aid in removing the completed molded packing. The apparatus 
may include means for automatically weighing the completed pad as a 
quality check to ensure uniform foam material. It should be apparent that 
if part of the foam material were to adhere to the cavity 74, as might 
occur if the separator sheet 71 ruptured, subsequently formed molded 
packings might have incomplete portions even though their weight might 
indicate a full load of foam material from the dispensing gun. The vacuum 
sensor described above ensures an advance warning of a ruptured separator 
sheet 71. 
As the mold box 244 continues from the ejection station 20 back to the 
preparation station 14, it is stationary at a rest station, indicated 
generally by the numeral 256, for an additional cycle. This station is 
necessitated by the geometry of the conveyor 10, there being no need for 
an additional work station. The geometry shown is particularly 
advantageous because it permits two mold boxes for forming upper molded 
packings and two mold boxes for forming lower molded packings to be 
installed on the apparatus simultaneously. The rest station 256 of the 
preferred embodiment may include sensing means such as a microswitch with 
pivoted arm, not shown, to indicate that a molded packing has been 
properly ejected and to prevent further cycling of the apparatus if a 
molded packing is present. 
The operation of the preferred embodiment may be summarized as follows. A 
separator sheet is fed from a supply roll into a pair of tracks which move 
the separator sheet over the top of a mold cavity. The separator sheet is 
then cut free from its supply roll by a hot wire. A plug pushes the 
separator sheet into the mold cavity and vacuum holds the separator sheet 
in place as the plug is removed. The mold cavity is then moved under a 
battery of dispensing guns which charge the mold cavity with foam 
material. When the mold cavity comes to rest, a fluid cylinder presses a 
cover prepared with a separator sheet or other parting agent over the mold 
cavity to contain the foam material during the curing process. After the 
foam material has sufficiently cured, the mold cavity is inverted and is 
moved to an ejection station where fluid cylinders, with or without the 
assistance of compressed air, push the completed molded packing out of the 
mold cavity. The empoty mold cavity is then moved in an upside-down 
position to the preparation station where it is turned upright to receive 
another separator sheet and repeat the sequence. 
These operation steps are carried out automatically with the aid of a 
timing device that coordinates the steps in sequence and duration, as 
indicated in FIG. 6. The indicated timing and sequence may be controlled 
by any of various commercially available microprocessors or other suitable 
timing devices to avoid the need for human intervention. However, it is 
preferred that the individual cycle at each station can be carried out 
independently for testing or for restarting following an emergency 
shutdown. Preferably, restart may be initiated only at the start of the 
cycle and on ready signals from all stations. 
The support structure of the apparatus may be formed of conventional 
materials such as steel and aluminum sections bolted or welded together 
into the configuration shown. The mold boxes 12 may be conveniently formed 
of steel and/or aluminum. Due to the low temperatures and pressures 
required relative to those required for molding cellular polystyrene, the 
mold cavity 74 can be formed inexpensively; for low production runs, such 
convenient materials as plywood may be used. One or more warning lights 
258 may be installed to indicate operation of the apparatus or sensing of 
a condition which requires attention. 
Applicant has determined that a suitable film for the rolls 84 and 224 is 
0.7 mil high-density polyethylene as supplied by Port Poly of Salem, N.H. 
or 1.5 mil low-density polyethylene as supplied by Armin Polyethylene Film 
of Elizabeth, N.J. Suitable polyurethane foam material for use with the 
present invention is freon or water blown semi-rigid or flexible urethane 
foam having a density of 0.4 to 0.7 pounds per cubic foot. Such foam 
material is commercially available, for example, as TR-240, FR-245, 
TR-250, or TR-257 supplied by International Packaging Systems of Norwalk, 
Conn. Other foam materials having densities of 0.25 to 4.0 pounds per 
cubic foot may also be used. 
Applicant has found that the present invention is particularly well suited 
to the formation of molded packings for cushioning computer terminals 
during shipment. The molded packings are placed above and below the 
terminal inside a corrugated carbon to absorb physical shock and vibration 
during shipment. The apparatus and method described herein have been 
successfully used to form individual molded packings having dimensions 
approximately 23 in..times.35 in..times.10 in. and weighing approximately 
2.0 lbs. A top molded packing and a bottom molded packing, each requiring 
a different constraining impression, are formed for each computer 
terminal. 
In this application just described, it has been found that the apparatus is 
capable of producing 1500-1600 molded packings (750-800 top and bottom 
pairs) within a 16-hour period by employing a stationary time of 18 
seconds at each work station and a moving time of 12 seconds between work 
stations. The total system for this application requires less than 250 
square feet of floor space. The apparatus can be positioned adjacent the 
assembly line of the computer terminals for convenient manufacture of the 
molded packings as they are needed. In this way, there is no need to store 
or transport bulky packings from a central manufacturing facility. 
From the foregoing, it should be apparent that the present invention can 
efficiently produce large quantities of molded packings of low-density 
resilient material for insertion between an article and a shipping 
container. The apparatus and method described herein permit fully 
automatic operation and ensure a consistent high quality of output. The 
molds for the molded packings may be replaced and/or changed easily to 
change the type of molded packing produced or to permit more than one type 
of molded packing to be produced alternately on a single apparatus. The 
apparatus is easily serviced and includes numerous safeguards to ensure 
that its operation is safe and in a predetermined, timed sequence. As a 
result of the inversion of the mold boxes at various stations, gravity 
assists the removal of completed pads and required floor space is reduced. 
Of course, it should be understood that various changes and modifications 
to the preferred embodiment described above will be apparent to those 
skilled in the art. For example, other means may be employed to deliver 
the separator sheet to the preparation station, and other types of 
conveyors or conveyors with additional work stations may be used. 
Similarly, other foam materials and parting agents may be used to achieve 
like results. Such changes and modifications can be made without departing 
from the spirit and scope of the present invention, and it is therefore 
intended that such changes and modifications be covered by the following 
claims: