Thermoforming machine with cutting press connected thereafter

An apparatus for the molding of thermoplastic synthetic resin sheet stock into articles and for punching these articles from the sheet length, including a thermoforming machine having a sheet conveyor with an intermittent drive, and a cutting press disposed immediately after the thermoforming machine and having a separate sheet conveyor for conveying the formed sheet material across the table of the cutting press. Each of the conveyors includes a sprocket conveyor chain guided for rotation on rotatably mounted sprocket wheels, and the conveyor of the cutting press is drivingly connected with the conveyor of the thermoforming machine in that the sprocket wheels at the mutually facing ends of the two conveyors are in operative connection with each other.

BACKGROUND OF THE INVENTION 
The invention relates to a thermoforming machine with a cutting press 
disposed or linked thereafter for the molding of thermoplastic synthetic 
resin sheet stock into articles and for punching these articles from the 
sheet length. For this purpose, the thermoforming machine comprises a 
forming station, a heating unit, and an intermittent feed arrangement for 
the stock material, while the cutting press comprises a vertically movable 
top platen with the cutting die, a rigid table, and a likewise 
intermittent material feed arrangement. 
The combination of a thermoforming machine with a cutting press connected 
thereafter is utilized in the series production of articles wherein, 
however, the series do not include excessively large numbers of pieces, 
i.e., wherein a tool performing both forming and cutting operations would 
be too expensive. This combination is furthermore advantageous in articles 
formed from a very thin sheet. The forming tools are relatively 
inexpensive, and economical strip steel dies can be used as the cutting 
dies. 
Although it is known to use a common material feed arrangement for both the 
cutting press and the thermoforming machine, and thus in effect 
permanently connect these two units together as a single unit (see for 
example British Pat. No. 1,277,226, issued June 7, 1972), it is 
preferable, for various reasons, if the cutting press is associated with 
the thermoforming machine as a separate unit, i.e., has its own material 
feed arrangement. For example, by providing the cutting press and 
thermoforming machine as separate units, it is readily possible to 
dismount the cutting press and associate same with another machine, if 
this is necessary for manufacturing reasons; thus, it may be necessary, 
depending on the article being formed, to connect for example, a belt saw, 
a simple cross cutter, or a guillotine after the thermoforming machine. 
Moreover, it is technically possible to operate the cutting press at a 
higher cycle rate than the thermoforming machine. This can be done if the 
forming tool molds simultaneously two or three article series or rows per 
cycle (multiple mold). In this case, a single-row cutting die is 
sufficient for the cutting press, which die can sever the thus-formed 
band. Thereby this cutting die becomes especially inexpensive, and the 
cutting forces required are not as high as when the entire output must be 
cut all at once. The cutting press has its own feed or conveyor 
arrangement for this purpose, conventionally a wiper feed or conveyor for 
the formed band or sheet. 
In the thermoforming machine a spiked sprocket chain has proved to be 
advantageous for use as the conveying system for the film sheet. Two such 
chains, which run in respective guide rails, are provided and engage the 
respective longitudinal edge zones of the sheet. The conveying systems 
terminates behind the forming station, so that it is possible thereafter 
to connect any further required machinery, e.g., cutting press, saw, cross 
cutter, etc. 
When linking a thermoforming machine with a separate conveying system of 
this type to the cutting press with its own wiper type conveyor system, 
problems are encountered in the case of very high articles, e.g., 
containers, in the case of articles formed of very thin sheet material, as 
well as in the case of articles wherein no knobs or protrusions which can 
be engaged by the wiper can be formed due to the contour of the articles 
and/or the position of the cutting edge. With very high articles, the 
wiper cannot be introduced in between the produced articles, since the 
lifting-off height is insufficient. In the case of articles of a very thin 
sheet, there is the danger that the wiper dents the sidewalls. 
It has been known in these cases merely to push the formed film sheet 
through the cutting press by means of the conveyor unit of the 
thermoforming machine and to effect a pull at the waste screen on the 
opposite side of the cutting press. However, with this arrangement, a high 
misalignment during the cutting step must be tolerated. 
SUMMARY OF THE INVENTION 
It is an object of the invention to provide a novel arrangement for linking 
a thermoforming machine and cutting press, each having a separate feed 
conveyor, so that it is possible to accurately cut out the articles, e.g., 
containers and which is also usable in case of high parts and parts formed 
of a thin sheet, as well as in case of parts which do not permit the 
integral molding of wiper knobs. In this connection, the heretofore 
existing possibilities of a rapid dismounting of the cutting press and of 
combining the thermoforming machine with other units, including the 
addition of a cutting press with a wiper feed feature, are to be 
maintained. 
The above object has basically and generally been attained according to the 
invention by providing the cutting press with a conveying means which can 
be directly connected to the conveyor of the thermoforming machine and 
runs synchronously therewith. In this way, the transport or conveyance of 
molded sheet stock is directly taken over by the conveyor of the cutting 
press and further transported synchronously through the cutting press. 
More particularly, the above object is achieved in that the thermoforming 
machine and the punch press are each provided with a conveying means which 
includes a sprocket conveyor chain which is mounted for rotation on 
rotatably mounted sprocket wheels, and means are provided for operatively 
connecting a sprocket wheel disposed at the output end of the conveying 
means of the thermoforming machine to a further sprocket wheel disposed at 
the input end of the conveying means of the cutting press so that the 
conveying means of the thermoforming machine is drivingly connected to the 
conveying means of the cutting press. 
According to the preferred embodiment, the two sprocket wheels are 
operatively connected in that each is provided with a set of gear teeth 
and the two wheels are positioned adjacent one another so that the 
respective gear teeth mesh. Preferably, the two sprocket wheels are 
arranged in super position and are appropriately spaced so that while the 
gear teeth mesh, the edge of the sheet of molded stock material passes 
between the sprockets. 
According to further features of the invention, the number of gear teeth 
and the number of sprockets on each sprocket wheel is the same; the 
sprockets and gear teeth are offset by one-half tooth pitch on one of the 
sprocket wheels while they are being aligned on the other sprocket wheel; 
and the lower disposed of the two sprocket wheels may be provided with a 
disk having a diameter such that the disk serves as a support for the 
molded sheet stock.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
Referring now to FIG. 1, there is shown a thermoforming machine 1 which 
operates in collaboration with a cutting press 2, so that the articles, 
e.g. containers, 4 can be prepared from synthetic resin sheet stock 
material 3 withdrawn from a roll 3' of such material. In this connection, 
the thermoforming machine 1 generally comprises a frame 5, a heating unit 
6 for the stock material, a forming of molding station 7 with a movable 
top and/or bottom portion containing the actual mold 8 as well as 
optionally vertically movable clamping frames, and a conveying arrangement 
9 for the sheet stock material 3. In a conventional manner, this conveying 
arrangement includes a pair of guide rails 10 (only one of which is shown) 
disposed along opposite edges of the frame 5, an actual, revolving 
conveyor chain 11 associated with each of the guide rails 10, and an 
intermittent drive, not shown, for the conveyor chains 11. The conveyor 
chain 11 is guided and supported on rotatably mounted sprocket wheels at 
the input and output ends of the conveyor 9. 
The thermoforming machine 1 is followed by the cutting press 2 which, for 
example, as further shown in FIG. 2, has a rigid platen or table 12, a 
vertically movable top platen 14 acted upon by a drive mechanism 15 and on 
which is mounted a strip steel die 16, a conveying or feed arrangement 13 
for the molded sheet material 17, as well as a waste reel-up arrangement 
18. 
According to the invention as illustrated in FIGS. 3-6, an arrangement is 
provided whereby the conveying means or arrangement 13 of the cutting 
press, which likewise includes a pair of guide rails 19 (only one of which 
is shown) and associated revolving conveyor chains 20 guided and supported 
on sprocket wheels, can be coupled with the sheet conveying arrangement or 
means 9 of the thermoforming machine 1. For this purpose, a plate 21 is 
attached to the output end of the guide rail 10 of the thermoforming 
machine and a sprocket wheel 23 for supporting and guiding the conveyor 
chain 11 is rotatably mounted on a pin or shaft 22 mounted on the plate 
21. In a similar manner, a plate 24 carrying a pin 25 is connected to the 
input end of guide rail 19 of the cutting press 2 and a sprocket wheel 26 
for supporting and guiding the conveyor chain 20 is rotatably supported on 
the pin 25. As shown in FIG. 5, each of the sprocket wheels is provided 
with a set of sprockets or teeth 28 and 30 respectively. As further shown 
in FIG. 5, every other link of each of the chains 11 and 20 is preferably 
provided with an outwardly directed spiked tongue 31 or 32 respectively 
for the purpose of engaging the edge of the sheet material to positively 
convey same. 
In addition to sprockets or teeth 28 for engaging the chain 11, the wheel 
23 is provided, on a portion of same having a larger diameter than the 
portion bearing the sprockets 28, with a set of gear teeth 27 with the 
number of gear teeth 27 being identical with the number of sprockets 28. 
In a similar manner, the wheel 26 is provided with a set of gear teeth 29 
having the same number of teeth as the number of its sprockets 30. It 
should be noted that in the illustrated embodiment each of the chains 11 
and 20 is shown as a double width chain and consequently the wheels 23 and 
26 are each provided with two rows of aligned side by side sprockets 28 
and 30 respectively. It is to be understood however that for purposes of 
determining the number of sprockets, each pair of aligned side by side 
sprockets is considered to be only one sprocket. 
While, as described above, the number of sprockets 28 and 30 and the number 
of gear teeth 27 and 29 are each wheel 23 and 26 respectively is the same, 
on one of the wheels 23 or 26 the sprockets and gear teeth are arranged so 
that they are displaced by one-half of the tooth pitch, i.e., so that each 
sprocket is radially aligned with the groove between two gear teeth, 
whereas on the other of the wheels 23 or 26 the sprockets and gear teeth 
are radially aligned. This is shown in FIGS. 5 and 6, which show the 
relationship of the sprockets 28 and 30 and of the gear teeth 27 and 29 at 
the same point in time and in FIG. 7. 
In order to couple the two conveying means 9 and 13, the plates 21 and 24 
are disposed or joined in such a manner that the sprocket wheels 23 and 26 
are superimposed, and so that the gear teeth 27 and 29 mesh with one 
another. As a result of the displacement or offset of the sprockets and 
gear teeth on one of the sprocket wheels 23 or 26 (the sprocket wheel 23 
as shown) and due to the fact that only every second link of the conveyor 
chains 11 and 20 carries a spiked tongue 31, the spiked tongue 31 of one 
conveyor chain always extends into the gap between the spiked tongues of 
the other conveyor chain as shown in FIG. 5. The formed or molded band 17 
thus is immediately taken over, upon leaving the sheet transport means 9 
of the thermoforming machine, by the conveyor 13 of the cutting press 2 
and guided without misalignment to the strip steel die 16. 
Preferably, as shown in FIG. 4, a disk 32 is attached to the end of the 
lower of the two sprocket wheels 23 and 26, the wheel 23 as illustrated. 
The diameter of this disk 32 is selected such that it contacts the lower 
surface of the molded sheet 17 and serves as support for the sheet length 
17 when the spiked tongues 31 of the conveying means 13 penetrate the 
molded sheet 17. 
Both conveying means 13 and 9 can be adjusted in their widths by way of 
respective threaded spindles 33 and 34 respectively and thus can be 
adapted to varying sheet widths. 
Due to the described construction according to the invention, it is 
possible, in a simple manner, to add or dismount the cutting press 2 
including the conveying means to or from the thermoforming machine 1 and 
to reequip the thermoforming machine correspondingly. A separate drive 
mechanism for the conveyor 13 of the cutting press 2 is unnecessary. In 
this way, it is also possible to subsequently supply an existing 
thermoforming machine with such a conveyor-equipped cutting press, without 
requiring extensive reconstruction of the thermoforming machine. 
Due to the feature that the spiked tongues 31 extend upwardly during the 
conveying operation in the thermoforming machine 1, but project downwardly 
during the conveying operation in the cutting press 2, format-adapting sub 
or understructures to accomodate varying sheet widths are not required 
when changes are made in the zone of the strip steel die. This has proven 
to be advantageous in this type of transfer. 
It is to be understood that the above description of the present invention 
is susceptible to various modifications, changes and adaptations, and the 
same are intended to be comprehended within the meaning and range of 
equivalents of the appended claims.