Machine trim press having counterbalance features

In accordance with one aspect of this invention an improved trim press is taught for use in separating molded articles from a web of material. The trim press includes a frame, a drive motor carried by the frame, a first platen carried by the frame, and a second platen carried by the frame and configured to be moved in reciprocation relative to the first platen. A first flywheel assembly is provided on the trim press having a weight with an eccentric mass, the weight being driven in rotation by the motor and coupled to drive the second platen via at least one kinematic linkage. The trim press also includes a second flywheel assembly having a weight with an eccentric mass, the weight being driven in rotation by the motor and coupled to drive the second platen via at least one kinematic linkage. In operation, the first flywheel assembly and the second flywheel assembly are constructed and arrange such that the eccentric mass of the associated weight on the first flywheel assembly is positioned in mirror image with the eccentric mass of the associate weight of the second flywheel assembly, the first and the second flywheel assemblies being driven in counter rotation so as to substantially cancel out dynamic forces produced out of the axis of movement of the movable platen. The flywheel assembly can also include an output shaft driven in rotation by the motor and a weight having interlocking features for mating the weight on the shaft for rotation.

TECHNICAL FIELD 
This invention relates to apparatus for separating thermal-formed thin 
walled plastic articles from a sheet of plastic material in which they 
have been formed. 
BACKGROUND OF THE INVENTION 
During the manufacture and forming of many products from sheets or webs of 
plastic material, thermal-forming machines are used to simultaneously mold 
large quantities of plastic thin-walled articles. A typical molded article 
is formed from one of a large variety of generally cup-shaped 
constructions, the article being formed between mating two-piece dies or 
molds suitable for imparting to the finished piece its final desired 
shape. A typical thermal-forming machine has a pair of mating male and 
female dies, or molds that are brought together on opposed sides of a 
pre-heated web of plastic material, during an operating cycle. Usually, a 
plurality of mating male and female dies are provided on bottom and top 
platens, or die carriers, respectively, enabling production of a plurality 
of articles during a single cycle of operation. 
According to one set-up, a separate trim press machine is provided adjacent 
to the thermal forming machine for separating the plurality of molded 
articles from the web of plastic material. A typical machine trim press is 
set up adjacent to the output side of the thermal forming machine, where 
it operates on the web of plastic material to remove the molded articles 
immediately adjacent to the location where they have been formed. A 
typical trim press has a fixed lower platen and a reciprocating upper 
platen. Each platen is configured transverse to the path of travel of the 
web of plastic material, so that they come together on opposite sides of 
the web, while the web and the in-molded articles are held in an accurate 
fixed position between the platens. Complementary cutting surfaces are 
formed in the top and bottom platens in locations that severe the 
in-molded articles from the web of material as the platens close onto the 
web. Typically, the movable upper platen has a spring seated clamp that 
engages with the top of the web, forcing it into engagement on its bottom 
face with the lower platen. In this manner, the clamp locks the web into 
position over the lower platen, just prior to engagement of the cutting 
surfaces and severing of the web about each article. Alternatively, a 
spring seated stripper carried on the lower platen strips the web off the 
lower die, and furthermore, acts as a spring seated clamp which holds the 
web during severing. 
Preferably, the lower platen is held in a fixed position, immediately 
beneath the web of material. In this manner, the lower platen also 
supports the web as it is fed into the trim press for a subsequent 
operating cycle. Typically, the web is fed into the trim press during the 
period of time that the upper platen is raised from the lower platen. As 
the upper platen is being lowered, the mechanism feeding the web is 
stopped at a desired location and the clamp (or stripper) further engages 
the web, fixing the web in an accurate location between the platens 
suitable to severe the articles therefrom. 
Modern thermal forming machines have provided vast productivity 
improvements by increasing the rate with which articles can be produced 
from a single machine. Many of these machines are driven by one or more 
electric drive motors. Alternatively, hydraulic or pneumatic actuators can 
be used to impart motion to a thermal-forming machine. Additionally, a 
control system or even a complex arrangement of kinematic linkages can be 
configured to choreograph the associated movements of feeding, heating, 
and forming of plastic articles by the machine. In fact, the use of 
computers and high speed processing has enabled vast improvements in cycle 
speed for thermal-forming machines. 
However, as the productivity of thermal-forming (thermoforming) machines 
has increased dramatically, trim presses have become the slow component of 
a forming and cutting operation, limiting the output of the entire line. 
State of the art trim presses need to more than double the existing 
maximum expected rate of 160 cycles per minute (cpm) to rates in excess of 
300 cpm. Such presently unsuitable state of the art devices include 
mechanical product picking devices, and even servo motor driven feed 
mechanisms. 
Therefore, improvements to trim presses are needed in order to enable the 
trimming of articles from a web, particularly during high speed 
thermal-forming, or molding operations. One problem results from high 
speed movement of the upper platen which shakes the trim press. As machine 
cycle speed increases, the dynamic forces created by the moving upper 
platen of the trim press greatly complicate the design of an accurate high 
speed trim press machine. Even where flywheels are added to the kinematic 
drive linkage on the press, oscillations can still occur in the rotational 
velocity of the flywheel. This can lead to jerky motion of the upper 
platen, resulting in poor high speed cutting performance. Therefore, 
improvements are needed to ensure accurate, uniform, and smooth closure 
between the top and the bottom platens of a trim press in order to ensure 
high speed and accurate cutting capabilities suitable to enable use of the 
trim press with a modern thermal-forming machine. Furthermore, 
improvements are needed to enhance cutting performance, by reducing 
imbalance forces created by the moving upper platen, while minimizing the 
required support structure of the machine. 
Another problem results from the speed limitations imposed when using 
traditional servo motor driven feed wheels to feed the web of material 
into the trim press. As the servo speed approaches 200 revolutions per 
minute (rpm), the feed wheels on each edge of the web can actually rip the 
web because the web is not strong enough to overcome the weight of the 
material in the web. One prior art technique has involved the use of pairs 
of wheels on each edge of the web, one (a drive wheel) having a plurality 
of circumferentially spaced apart and radially extending picks which 
perforate the web along each edge, to engage the web and enable feeding 
there along, and the other acting as a follower wheel. However, such 
constructions tend to tear the web, and are not capable of producing 
speeds necessary to exceed 160 cycles per minute (cpm). In fact, to feed a 
web of material into a trim press that is running at 400 cpm, the servo 
motor and wheels will run at about 2,000 rpm. Therefore, additional 
improvements are needed in order to enable the feeding of a web of plastic 
material into an improved high speed trim press. 
The objective of the present invention is to provide a vastly improved 
machine trim press having features for reducing the dynamic operating 
forces and to enable high speed feeding of a web of plastic material into 
the trim press. Furthermore, features are desired for offsetting undesired 
dynamic imbalance forces in an operating trim press while at the same time 
producing smooth axial cutting forces, resulting in precise and accurate 
cutting of articles from a web of material during a forming operation, 
such as a thermal-forming cycle of a thermal-forming machine.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
This disclosure of the invention is submitted in furtherance of the 
constitutional purposes of the U.S. Patent Laws "to promote the progress 
of science and useful arts" (Article 1, Section 8). 
In accordance with one aspect of this invention an improved trim press is 
taught for use in separating molded articles from a web of material. The 
trim press includes a frame, a drive motor carried by the frame, a first 
platen carried by the frame, and a second platen carried by the frame and 
configured to be moved in reciprocation relative to the first platen. A 
first flywheel assembly is provided on the trim press having a weight with 
an eccentric mass, the weight being driven in rotation by the motor and 
coupled to drive the second platen via at least one kinematic linkage. The 
trim press also includes a second flywheel assembly having a weight with 
an eccentric mass, the weight being driven in rotation by the motor and 
coupled to drive the second platen via at least one kinematic linkage. In 
operation, the first flywheel assembly and the second flywheel assembly 
are constructed and arrange such that the eccentric mass of the associated 
weight on the first flywheel assembly is positioned in mirror image with 
the eccentric mass of the associate weight of the second flywheel 
assembly, the first and the second flywheel assemblies being driven in 
counter rotation so as to substantially cancel out dynamic forces produced 
out of the axis of movement of the movable platen. 
In accordance with another aspect of this invention an improved trim press 
usable for severing formed articles from a web of material is taught. The 
trim press includes a frame and a drive motor carried by the frame. The 
trim press also includes a first platen carried by the frame and having a 
first cutting feature, and a second platen movably carried by the frame 
and having a second cutting feature configured to coact with the first 
cutting feature. The second platen is configured to be axially 
reciprocated relative to the first platen, causing the first and the 
second cutting features to open and close so as to cut a web of material 
positioned therebetween. Furthermore, the trim press includes a flywheel 
assembly having an output shaft driven in rotation by the motor and a 
weight having interlocking features for mounting the weight on the shaft 
for rotation. The weight is mounted in mated engagement with the shaft 
such that mass of the weight is offset from the center of rotation, the 
shaft being coupled to drive the second platen via at least one kinematic 
linkage. 
A preferred embodiment of an improved machine trim press is generally 
designated with the reference numeral 10. According to FIG. 1, an array of 
cups 11 are formed in a web of thermo-formable plastic material 13 by a 
thermal forming machine (not shown). Web 13 is intermittently fed between 
an upper platen 12 and a lower platen 14 by a conveyor (not shown) which 
intermittently progresses the web through a molding machine where cups are 
formed in the web, and into position between the trim press platens 12 and 
14 where the cups are severed from the web. The conveyor preferably 
comprises a dual servo motor driven roller feed assembly, to be discussed 
in greater detail below with reference to FIGS. 3 and 8. Once web 13 is 
clamped against the upper platen via a spring-biased clamp (not shown) on 
the lower platen, such as a stripper carried by the lower platen 14, the 
platens can be completely closed together by press 10, severing the 
articles 11 from web 13. A parts handling machine (not shown) is carried 
by the frame of the trim press, along the exit side, for removing and 
stacking articles as they are severed from web 13. After removing each 
article 11 from web 13, a hole 15 is left in the scrap portion of web 13. 
The resulting scrap portion of web 13 is then forwarded into a recycling, 
or pulverizing machine where it is shredded and recycled. Details of one 
exemplary recycling machine are disclosed in U.S. Pat. No. 4,687,144, 
"Apparatus for Comminuting Waste Materials", hereby incorporated by 
reference. 
Details of one exemplary thermal-forming machine are disclosed in U.S. 
patent application Ser. No. 08/632,930, "An Improved Mold Assembly and 
Seal Arrangement for Use With A Thermo-Forming Machine", listing Jere F. 
Irwin, Gerald M. Corbin, and Dale L. Vantrease as inventors. This patent 
application and resulting patent are hereby incorporated by reference as 
if fully included herein. 
In operation, a servo motor 16 carried on an upper frame 17 of press 10 
drives a pair of flywheel assemblies 18 and 20, each in a counter rotating 
motion relative to the other. A cross member 19 retains a pair of 
substantially parallel plates 21 on frame 17 in rigid spaced apart 
relation for carrying assemblies 18 and 20. Four, vertical rail members 
(not shown) secure upper frame 17 to platen 14, and further support a 
perforated steel mesh cage (not shown) about press 10 for protecting 
operators from injury during use. 
Each flywheel assembly 18 and 20 forms a rotating eccentric mass having a 
center of gravity that is offset from its axis of rotation. The rotating 
mass of each assembly 18 and 20 are driven so that dynamic forces produced 
from the rotation of each eccentric mass is additive in the direction of 
motion of the upper platen 12, and substantially cancels out (or 
counterbalances) in all other directions within the rotating plane of the 
masses. A pair of weights 22 on each assembly 18 and 20 are securely 
mounted to the assembly eccentrically of their axis of rotation to form 
the eccentric, or offset mass. When spun, the offset weight of each mass 
produces dynamically imbalanced rotational forces that would normally 
impart centrifugal forces to press 10. However, since the pair of weights 
22 in each assembly 18 and 20 are configured to be spun in counter 
rotating relation, they substantially cancel out the imbalance forces in 
all directions other than the direction of motion for upper platen 12. 
As a result of the above, the counter rotating motion of assemblies 18 and 
20 produces a net axially reciprocating imbalance force acting in the 
direction of motion of upper platen 12. Preferably, the weights are sized 
and positioned so that the resulting axially reciprocating force 
substantially cancels out an axially reciprocating force produced by the 
reciprocating motion of upper platen 12, including associated crank arm 
assemblies. When platen 12 reaches its lower most position, the resulting 
centrifugal forces from the flywheel assemblies are greatest, which 
offsets forces produced by the moving upper platen 12. Likewise, when 
platen 12 reaches its highest most position, the resulting centrifugal 
forces from the flywheel assemblies is greatest, which offsets forces 
produced by the moving upper platen 12. Such produces highly desirable 
substantially balanced dynamic forces that assist in smoothly and evenly 
cutting a web of material as it is intermittently passed between platens 
12 and 14. Hence trim press 10 is highly balanced, enabling faster 
operating speeds. Furthermore, the overall mass of the flywheel assemblies 
can be reduced, while still producing a smoothly operating press 10. 
Even more importantly, the cancellation of any dynamic flywheel forces 
off-axis from the direction of motion of platen 12 results in a smooth 
reciprocating motion of platen 12. In this manner, the need to provide a 
large number of highly enforced guide members to ensure an accurate 
cutting operation is reduced, or even eliminated. Essentially, the drive 
assembly that reciprocates platen 12 also serves to align the platen, 
while press 10 still produces the necessary dynamic cutting forces for 
offsetting forces produced by moving platen 12 via the coaction of the 
flywheel assemblies. 
In this manner, smooth dynamic cutting forces can be produced with a 
balanced press design that is relatively light in weight, has reduced 
vibration, and does not require substantial vertical guide support to 
maintain smooth axial reciprocation of the upper platen during operation. 
In contrast, prior art devices have required the use of four large 
vertical guide supports and guide bushings, one pair being provided at 
each corner of the movable platen. 
Flywheel assemblies 18 and 20 are each formed from an output shaft 24 which 
is supported for rotation at either end by a rotating bearing assembly 26. 
A throw arm 28 is fixedly mounted to each end of each shaft 24 to form a 
drive arm for driving platen 12 in vertically reciprocating motion. Throw 
arm 28 is driven in rotation by the shaft, which in turn is driven by 
drive motor 16. The radial outermost end of each arm 28 is pivotally 
mounted to a platen connecting rod 30, along an upper end portion. A lower 
end portion of rod 30 is then pivotally mounted to platen 12. In this 
manner, rod 30 and throw arm 28 form a crank arm assembly 31 that drives 
platen 12 in reciprocating motion, at each corner. By rotating shafts 24 
in synchronized fashion, with throw arms 28 being positioned in opposed 
symmetric relation, platen 12 can be caused to move vertically with single 
degree of freedom motion such that its contact surface remains 
substantially parallel with lower platen 14 throughout a cycle of 
operation. Such ensures parallel and even closure between the platens, 
greatly reducing wear between cutting surfaces carried by the upper and 
the lower platens 12 and 14, respectively. 
Motor 16 is formed from a servo driven alternating current (AC) motor that 
has built-in encoders for monitoring the position of the drive shaft. In 
this manner, motor 16 of FIG. 1 can be computer controlled so as to 
accurately drive reciprocation of upper platen 12 in relation to forward 
positioning of web 13 by a separately driven servo motor feed conveyor 
(not shown), which is also computer controlled. Even further, a thermal 
forming machine (not shown) provided upstream of press 10 forms articles 
11 in the web via a similar computer controlled servo driven motor device. 
Preferably, a single, common computer controls and choreographs operation 
of the thermal forming machine, conveyor and press 10. One suitable servo 
drive motor is presently sold by Siemens AG of Germany, under the trade 
name of SIMODRIVE 611-A, and includes transistor PWM inverters and motors 
for AC feed drives. The associated servo driven motors and computer use a 
high speed digital signal processor running at 40 MHz (40 million cycles 
per second) or more, which can interrogate 2,500 encoder pulses per 
revolution when the motor is running at 2,000 rpm. Such processing speeds 
enable the computer and drives of each machine to react within one encoder 
pulse after receiving a registration signal from the product being fed. 
Such servo motors comprise high speed, brushless servo motors that are 
capable of running at speeds unattainable with previous technology. Hence, 
trim press speeds and web feeding speeds need to be improved according to 
the aspects of this invention. Further details will be discussed below 
with reference to FIGS. 3 and 8. 
Drive motor 16 is mounted to frame 17 such that its output shaft drives a 
pair of coupled together input shafts 36 on gearbox assemblies (or 
transfer cases) 32 and 34 for driving flywheel assemblies 18 and 20, 
respectively. The inputs shafts 36 of each gearbox assembly 32 and 34 are 
configured in substantially collinear relation with the drive shaft of 
motor 16. An output shaft 24 extends through each gearbox assembly 32 and 
34, where bevel gears couple each input shaft 36 with each associated and 
perpendicularly extending output shaft 24. An outermost end of input shaft 
36 on assembly 18, positioned opposite motor 16, has a pair of flat 
surfaces configured to receive a wrench so as to enable rotation of the 
shaft during repair, maintenance and servicing. 
To further ensure accurate axially reciprocating motion of platen 12 
relative to stationary platen 14, a pair of primary guide posts 38 are 
fixedly mounted between upper frame 17 and platen 14, along the web entry 
side of press 10. As shown in FIG. 1, a pair of secondary guide posts 40 
are similarly fixedly mounted between upper frame 17 and platen 14. Posts 
38 and 40 also serve to support upper frame 17 on lower platen 14. Yet 
another secondary guide post 42 (see FIG. 2) is mounted on frame 17, above 
plate 12, and along the web exit side of press 10. Primary guide posts 38 
slidably receive a bronze bushing assembly so as to axially guide platen 
12 along guide posts 38. Bushing assemblies 44 each contain a porous 
bronze bushing configured to retain a supply of lubricating grease. 
Furthermore, bushing assemblies 44 and posts 38 are accurately sized and 
positioned so as to ensure accurate axial alignment between platens 12 and 
14. 
In contrast, secondary guide posts 40 and 42 serve primarily to guide and 
support a part handling machine (not shown) that is configured to remove 
and stack articles as they are cut from web 13, as well as to guide the 
exiting scrap portion of web 13 into a recycling machine. Hence, posts 40 
are sized significantly smaller than posts 38, and for certain 
applications, don't even receive any bushing assemblies for attaching to 
platen 12. Optionally, posts 40 can receive downsized bushing assemblies 
for providing additional axial support and guidance, but accurate 
dimensional tolerancing is not necessary over that already provided by 
posts 38 and bushing assemblies 44 as a result of the construction of this 
invention. 
According to the construction of FIG. 1, platen connecting rods 30 are each 
formed from a pair of forged aluminum arms that are connected together 
with a threaded rod. Each rod is threaded at each end so as to provide 
adjustment of the length of the rod when aligning upper platen 12 during 
set up relative to lower platen 14. Each arm receives a pair of threaded 
fasteners to fixedly receive the rod into each arm, locking the overall 
length of rod 30 to the desired threadingly adjusted length. Furthermore, 
each arm in assembly receives a bearing assembly which facilitates pivotal 
mounting of each end of rod 30 to an associated throw arm 28 and platen 
12, respectively. 
FIG. 2 illustrates trim press 10 in a vertical front view with the front 
plate of frame 17 partially broken away in order to view the mounting 
relationship between motor 16 and flywheel assemblies 18 and 20. Platen 12 
is shown in a lowered, or closed position on the die frame of platen 14. 
In this view, the collinear relationship of motor 16 and its drive shaft 
with the input shafts 36 on assemblies 18 and 20 can be clearly seen. 
Input shafts 36 for each assembly 18 and 20 are joined together with a 
pair of chain couplings 48 and an extension shaft 50. A sub-frame 52 
mounts the gear boxes 32 and 34 together in spaced apart relation, 
supporting them within frame 17. Additionally, sub frame 52 mounts to 
motor 16, supporting it at one end in fixed relation with the pair of gear 
boxes 32 and 34. The entire resulting assembly is then supported within 
frame 17 via the pairs of bearing assemblies 26 and the gear box output 
shafts. The output shaft of motor 16 is then connected with the gear box 
input shafts 36 (and extension shaft 50) via a coupling connector 54. 
According to the construction of FIGS. 1 and 2, platens 12 and 14 each 
removably carry a die member 57 and 59, respectively, which forms part of 
each platen. The die members 57 and 59 each contain a plurality of 
associated male and female cutting features 56 and 58, respectively, which 
coact to sever articles from the web of material while it is positioned 
there between. Accurate placement of the web and molded articles via a 
computer controlled servo motor driven conveyor (see FIG. 3) and operation 
of trim press 10 via computer controlled motor 16 allows for accurate 
cutting of articles from the web via coaction of features 56 and 58. 
Preferably, male cutting feature 56 comprises a circumferential steel 
ring, lowered below the bottom die surface, and a clearance cavity or 
channel 98 (see FIG. 7) which receives trimmed product after it has been 
severed between the platens 12 and 14. Similarly, female cutting feature 
58 comprises a receiving slot, or lowered surface having an edge that 
coacts with the ring of feature 56, creating a scissors action that severs 
the web therebetween. Preferably, a spring loaded stripper forms the 
lowered surface, as the male cutting feature engages the stripper, 
enabling cutting of the web and subsequent removal of the web from the 
lower platen (see FIG. 7). 
FIG. 3 shows a vertical side view of the trim press taken from the right 
side, as viewed in FIG. 2. Accordingly, the raised position of platen 12 
can be clearly seen, with throw arms 28 rotated upwardly so as to present 
platen 12 at its highest most position. Also shown in dashed lines is the 
lowest most, or lowered position of platen 12, corresponding with throw 
arms 28 being rotated downwardly to a vertically lowered orientation. 
Additionally, the secondary contribution of posts 40 and 42, which serve 
primarily to mount a parts handling machine, can be clearly seen. 
Optionally, a pair of small bushing assemblies, similar to bushings 44 can 
be added to platen 12 for slidably guiding it along posts 40. However, 
their contribution for ensuring axially accurate reciprocation of platen 
12 is not necessary according to the machine vibration-reducing 
improvements of this invention resulting from counter rotating the 
flywheel assemblies via four kinematic linkages, in the form of crank arms 
31 (see FIG. 1). A plurality of threaded bolts and washers are also shown 
along the edge of plates 21 for affixing frame 17 to the vertical frame 
members (not shown) that support upper frame 17 atop platen 14 and further 
serve to carry a protective cage about press 10. 
FIG. 3 also depicts a conveying mechanism comprising a dual servo motor 
driven roller feed assembly for intermittently feeding web 13 through 
press 10. Preferably, two sets of side-by side pairs of roller assemblies 
47 and 49, are provided along each of the outer, or free edges of web 13 
so as to not interfere with articles formed in the web. A pair of servo 
driven motors 51 and 53 each drive a set of the side-by-side left and 
right edge roller assemblies, the first set 47 of left and right roller 
assemblies pulling web 13 from a thermal forming machine (not shown) 
toward press 10, and the second set 49, or pair of left and right roller 
assemblies assisting the first set in pulling web 13 from press 10 at high 
speed. In this manner, web 13 can be fed at a much higher speed from 
between platens 12 and 14, greatly increasing the achievable cycle speed 
of press 10. In some cases, slop or excess web material can be 
accommodated between the pairs of roller assemblies, depending on the 
operating conditions. 
Each set of roller assemblies 47 and 49 are formed from a pair of left and 
right roller assemblies, each assembly having a drive wheel and a follower 
wheel. The drive wheel is formed from an aluminum wheel which is anodized 
and has a sandpaper radial outermost finish. The idler, or follower wheel 
is formed from a neoprene wheel that is forced into biased engagement with 
the web and drive wheel via one or more air cylinders (not shown). In this 
manner, the drive wheel forms a grippy wheel that engages and drives the 
web along a corresponding outer edge. The side-by-side set of roller 
assemblies 47 forms a feed servo mechanism, powered by brush-less servo 
motor 51. Similarly, the side-by side pair of left and right roller 
assemblies (one on the left edge of the web and one on the right edge of 
the web) of roller assemblies 49 forms a helper servo mechanism, powered 
by brush-less servo motor 53. Additionally, a third pair of roller 
assemblies (not shown) can be provided on the exit side of press 10 to 
facilitate feeding of scrap web into a recycling machine. Both the feed 
servo mechanism and the helper servo mechanism are directed under computer 
control via computer controller 55. Motors 51 and 53 are preferably 
constructed and run according to details of the previously disclosed motor 
16 (of FIG. 1). 
In order to computer choreograph the cycle speed of press 10 in matched 
relation with the position of web 13, the servo drive motors are coupled 
with a servo motor controller 55 and a machine-based computer system. 
Controller 55 serves to maintain the conveying of web 13 in 
synchronization with an adjacent thermal forming machine (not shown), and 
with operation of press 10. Hence, press 10 is able to maintain an 
accurate cutting of a lip-edge of web material about each article molded 
into web 13. By providing a helper servo mechanism, the web can be fed 
fast enough to allow the trim press to run (at 400 cpm) a row of molded 
cups with substantially perfect registration. Such occurs without causing 
the web to rip along the edges. Therefore, higher speeds can be attained 
with an additional servo feeding mechanism that is feeding the final servo 
mechanism but with a somewhat less radical movement in order to help the 
first (feed) servo mechanism to accomplish its high speed, accurate feed 
without having to overcome the resistance of the weight of the complete 
web. If the combination of a feed and a helper servo mechanism are not 
used, then as servo feed speeds approach 200 rpm, the feed wheels can 
actually rip the web because the web is not strong enough to overcome the 
weight of the material in the web. Together, the feed and helper servo 
mechanisms enable the trim press 10 to accommodate the increased 
production of modern thermal forming machines. Hence, motor speeds of 
2,000 rpm with 2,500 encoder pulses per revolution on the conveyor are 
possible, enabling full use of modern high speed digital signal processing 
capabilities running at processing speeds of 400 MHz or more. 
FIG. 4 illustrates in plan view the layout of trim press motor 16, the 
drive assembly formed by gear boxes 32 and 34, extension shaft 50, and 
chain couplings 48, and the counterbalance features of flywheel assemblies 
18 and 20. A plurality of threaded bolts and washers are shown along the 
top edges of plates 21 for affixing frame 17 to cross members that extend 
from the vertical frame members (not shown), supporting upper frame 17 
atop platen 14, and carrying a protective cage about press 10. According 
to the position depicted in FIG. 4, weights 22 are shown rotated in a 
vertically raised orientation. By sizing the weights so that they match, 
it becomes easy in FIG. 4 to visualize the cancelling out of imbalance 
forces in directions not collinear with movement of platen 12 caused by 
counter rotating the weights 22 on assemblies 18 and 20. 
FIG. 5 illustrates an exploded vertical cross-sectional view of one of the 
counter-balanced flywheel assemblies, namely flywheel assembly 18. Shaft 
24 is shown is dashed lines, and forms part of gearbox 32 wherein a pair 
of bevel gears connect shaft 24 with input shaft 36. One of weights 22 is 
mounted securely to shaft 24, on each side of gear box 32. Shaft 24 is 
then received through one of the bearing assemblies 26 as carried within 
an aperture of each plate 21, on each side. One of throw arms 28 mounts to 
each end of shaft 24 for driving the upper platen via one of the platen 
connecting rods 30. To promote relative rotation between each throw arm 28 
and rod 30, a bearing assembly 46 is provided therebetween where they 
affix to one another. Flywheel assembly 20 is similarly constructed. 
More particularly, each weight 22 is formed from a tear drop shaped 
weighted member 60 having a mounting notch 62 that is constructed and 
arranged to mate in interlocking engagement with a complementary pair of 
flat faces formed in shaft 24. Preferably, each member is formed from one 
or more pieces of thick plate steel. Preferably a pair of faces formed at 
ninety degrees to one another are provided on the shaft, for mating with 
notch 62. Other shaft surfaces and notch shapes which interlock are 
possible. A clamping collar 66 having a substantially semi-circular mating 
face engages with shaft 24 in assembly, along a side opposite faces 64, 
ensuring positive interlocking engagement between weighted members 60 and 
shaft 24. A plurality of threaded fasteners, such as bolts, secure collar 
66 to member 60, trapping shaft 24 securely therebetween. Such a 
construction creates a strong and durable shaft mount for retaining each 
eccentric mass 22 to shaft 24. 
With the substantial resultant dynamic imbalance forces that eccentric 
weights 22 can together produce when placed in high speed rotation, the 
mounting features of this invention allow one to operate a trim press at 
higher speeds while minimizing the flywheel mass needed to produce forces 
that substantially offset dynamic forces produced by reciprocating 
movement of upper platen 12. This leads to a smooth rotational velocity of 
each shaft supporting each rotating weight. Therefore, the resulting trim 
press is better able to keep up with the decreasing cycle times found on 
modern computer controlled thermal forming machines, allowing for 
increased production rates that accommodate the enhanced web conveying 
features of this invention. Even further, web cutting accuracy is 
maintained, while at the same time smooth cutting forces are produced by 
the movement of the eccentric flywheel via the counter rotating assemblies 
which cancel out imbalance forces produced in directions not collinear 
with the axis in which the upper platen is moving, and cancel out dynamic 
inertial forces produced from the moving (reciprocating) platen. 
As shown in FIG. 5, each bearing assembly 24 is formed by a multiple piece 
construction providing a bearing 74 that is mounted within an aperture in 
plate 21 of the press upper frame. An inner retaining collar 70 and an 
outer retaining collar 72, respectively, of the assembly retain bearing 74 
within the aperture of plate 21. A plurality of threaded fasteners 78 
secure collar 70, plate 21 and collar 72 together, retaining bearing 74 
therebetween. A press fit support sleeve 76 is then received over shaft 
24, and press fit within the inner race of each bearing 74, forming a snug 
and centered rotatable support for shaft 24 within plates 21. 
Further according to FIG. 5, throw arms 28 are each mounted to opposite 
ends of shaft 24 with a plurality of threaded fasteners 80. An aperture in 
throw arm 28 receives an end of shaft 24 snugly therein. A plurality of 
complementary threaded female bores are formed within each end of shaft 24 
for receiving fasteners 80 therein in assembly. In this manner, arm 28 is 
securely fixedly mounted to shaft 24, producing a very strong torsional 
fixturing between arm 28 and shaft 24. Such a mounting is necessary in 
order to accommodate the dynamic forces produced while operating the trim 
press. 
Even further according to FIG. 5, bearing assemblies 46 are retained within 
a bore in each arm 30 via a plurality of threaded fasteners 82 and a 
shouldered mounting post 84. Each bearing assembly includes the post 84, 
fasteners 82, a bearing 86 and a face mounting ring 88. Ring 88 seats 
between the inner race of bearing 86 and an outer shoulder on arm 28, 
forming contact surfaces therealong. Accordingly, each bearing assembly 46 
mounts an associated platen connecting rod 30 in rotatable relation with 
an associated throw arm 28, the throw arms being driven in rotation via 
shafts 24 and 36 by the servo drive motor 16 (see FIG. 4). 
FIG. 6 shows an exploded perspective view of one of the counterbalanced 
flywheel weights 22 of the trim press of FIGS. 1-5 illustrating mounting 
features for attaching each weight 22 to the associated drive shaft 24. 
Accordingly, the notch 62 provided in weighted member 60 and its 
interlocking association with faces 64 of shaft 24 when assembled can be 
clearly seen. By securely threading fasteners 68 through clearance 
apertures 92 of collar 66 and into complementary threaded bores of member 
60, weight 22 is securely retained onto shaft 24, preventing any relative 
rotation therebetween. Such a construction has proven rugged and durable, 
and necessary in light of the considerable imbalance forces that are 
produced when spinning the eccentric mass of weight 60 about shaft 24, 
particularly when done at a high rate of rotational speed. Alternative 
constructions which lack physical interlocking features between weight 60 
and shaft 24 have proven ineffective for long term use because of these 
large forces, including the use of through pins or bolts which extend 
through a bore in shaft 24 and into weight 60. Additionally, each end of 
shaft 24 is secured to each throw arm 28 via mating spline features 91 and 
93, respectively, and threaded fasteners (not shown). Weight 60 also 
includes a plurality of apertures 90. 
FIG. 7 illustrates a vertical centerline sectional view of one exemplary 
pair of cutting features 56 and 58 formed in the die members of the top 
and bottom platens 12 and 14, respectively, of trim press 10. Such 
features 56 and 58 are configured for cutting a cup 11 away from web 13 in 
which it has been thermal formed. Many alternative configurations are 
possible for cutting any of a number of differently shaped articles from a 
web of material. Similarly, the web of material can be formed from a 
thermo-formable plastic, metal, foam or any of a number of die and heat 
formable webs of material. 
According to FIG. 7, male cutting feature 56 has a ridge, or ring 100 which 
forms a circumferentially extending cutting edge 94, and a clearance 
cavity, or channel 98 for enabling clearance of cup 11 during a cutting 
and severing operation as the press is closed thereon. Channel 98 receives 
the trimmed product where it is either stored, or directly removed from 
another end. Portions 104 of platen 12 separate adjacent channels 98. 
Female cutting feature 58 has a recessed portion 102 which forms a 
complementary circumferentially extending cutting edge 96. A stripper 
comprising one or more stripping plates 106 is movably supported within 
recessed portion 102. Edges 94 and 96 coact to sever web 13 about cup 11, 
leaving a radially outwardly extending flange about cup 11. Normally, the 
resulting flange is rolled back toward the body of the cup via a 
secondary, and subsequent thermal forming operation, forming a smooth 
rolled lip edge that is more compatible with a user's lips and mouth. 
Preferably, features 56 and 58 are formed in die members 57 and 59 of 
platens 12 and 14, respectively, the die members being removably mounted 
with the platens to facilitate quick and easy changing of the cutting 
features to suit particular desired forming and cutting operations. 
Stripper plate 106 is carried in a spring biased elevated position via 
springs 109. A plurality of shoulder bolts 108 limit the maximum raised 
position of the plate, slightly above the top surface of the die. As ridge 
100 engages web 13 and plate 106, plate 106 is downwardly biased, enabling 
edges 94 and 96 to coact and sever the web. Subsequently, as platen 12 is 
raised, stripper plate 106 raises via springs 109 to ensure release of 
severed web 13 from around edge 96 of lower die 14. Such prevents catching 
of web 13 on lower platen 14, allowing for continued and uninterrupted 
subsequent operating cycles. Furthermore, plate 106 acts as a spring 
biased clamp to secure web 13 during cutting of web 13. 
FIG. 8 illustrates an alternatively configured trim press of this invention 
taken from a side corresponding to that shown in FIG. 2 and illustrating a 
horizontally configured trim press 10 having a dual servo motor driven 
roller feed assembly. Trim press 10 is the same as press 10 of FIGS. 1-7, 
except the mounting frame is configured to support the press in a 
horizontal position. A conveyor assembly is also mounted atop the frame 
for feeding a web 13 into the press where formed articles are trimmed from 
the web. The conveyor assembly runs just like the conveyor of FIG. 3, 
except for the horizontal arrangement of press 10. However, to support web 
13 for feeding via a feed servo mechanism and a helper servo mechanism, a 
leading pair of edge supports 112 and a trailing pair of edge supports 114 
guide and support web 13 along each edge so that the two sets of side-by 
side pairs of roller assemblies 47 and 49 can feed web 13 at high speed 
into press 10. Similar to FIG. 3, servo motors 51 and 53 are controlled 
and choreographed via computer controller 55. By providing servo driven 
wheels at the edges of the web, the web is driven only along the edge, and 
the web is not damaged by pick fingers (as used in the prior art). By 
including an optical product sensor, the computer controller can locate 
the web and formed articles, enabling index length and product 
registration to be computer controlled, allowing for adjustment of the web 
on the fly. Hence, indexing is faster, so higher trim press speeds may be 
possible. Furthermore, many materials can be run through such a device, 
including foam, solid sheet, and film. 
In compliance with the statute, the invention has been described in 
language more or less specific as to structural and methodical features. 
It is to be understood, however, that the invention is not limited to the 
specific features shown and described, since the means herein disclosed 
comprise preferred forms of putting the invention into effect. The 
invention is, therefore, claimed in any of its forms or modifications 
within the proper scope of the appended claims appropriately interpreted 
in accordance with the doctrine of equivalents.