U.S. patent application number 15/161752 was filed with the patent office on 2016-09-15 for method for processing thermoplastic films, thermoforming system, film supply station, film strip, use, and laminated part.
This patent application is currently assigned to Kiefel GmbH. The applicant listed for this patent is Kiefel GmbH. Invention is credited to Reiner HUBER, Gernold STAEMMLER.
Application Number | 20160263819 15/161752 |
Document ID | / |
Family ID | 46196955 |
Filed Date | 2016-09-15 |
United States Patent
Application |
20160263819 |
Kind Code |
A1 |
STAEMMLER; Gernold ; et
al. |
September 15, 2016 |
METHOD FOR PROCESSING THERMOPLASTIC FILMS, THERMOFORMING SYSTEM,
FILM SUPPLY STATION, FILM STRIP, USE, AND LAMINATED PART
Abstract
A thermoforming system for carrying out a method for processing
two different thermoplastic films has a thermoforming station for
processing the different films, a transport device for transporting
the film to the thermoforming station, and a connecting station for
connecting successive blank cuts so as to form a film strip. Cuts
of the one or the other film are selectively and variably brought
on request in a conveyor through the thermoforming system, such
that different successive cuts are conveyed by the conveyor to the
thermoforming station and processed therein, and two successive
cuts are joined into a film strip, either edge to edge or with an
overlap.
Inventors: |
STAEMMLER; Gernold; (Anger,
DE) ; HUBER; Reiner; (Ainring, DE) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Kiefel GmbH |
Freilassing |
|
DE |
|
|
Assignee: |
Kiefel GmbH
Freilassing
DE
|
Family ID: |
46196955 |
Appl. No.: |
15/161752 |
Filed: |
May 23, 2016 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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14001706 |
Sep 6, 2013 |
9375875 |
|
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PCT/DE2012/000185 |
Feb 28, 2012 |
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15161752 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
B29K 2995/0021 20130101;
B29L 2031/3005 20130101; B29C 51/02 20130101; B29K 2105/256
20130101; B29C 51/16 20130101; B29C 51/46 20130101; B29C 51/262
20130101; Y10T 428/192 20150115; B29C 51/264 20130101; B29C 65/741
20130101; B29C 51/421 20130101 |
International
Class: |
B29C 65/74 20060101
B29C065/74; B29C 51/42 20060101 B29C051/42; B29C 51/02 20060101
B29C051/02; B29C 51/26 20060101 B29C051/26; B29C 51/46 20060101
B29C051/46 |
Foreign Application Data
Date |
Code |
Application Number |
Feb 28, 2011 |
DE |
10 2011 012 617.1 |
Claims
1. A thermoforming system, set up for carrying out a method for
processing two different thermoplastic films, comprising: a
thermoforming station for processing the different films; a
transport device for transporting the film to the thermoforming
station; and a connecting station for connecting successive blank
cuts so as to form a film strip; wherein on request, blank cuts are
selectively and varying from one film to another one brought in the
transport device through the thermoforming system so that different
blank cuts are successively transported by the transport device to
the thermoforming station and are processed there; and wherein two
successive blank cuts are connected to one another so as to form a
film strip.
2. The thermoforming system according to claim 1, further
comprising a plurality of roll holders for film rolls, in
particular with an unwinding device and a separating device for
preparing the blank cuts.
3. The thermoforming system according to claim 1, further
comprising a controller that is set up for processing a request for
a certain film, and thereupon controls a film so that a blank cut
is made therefrom and is connected to an adjacent blank cut so as
to form a film strip.
4. The thermoforming system according to claim 1, further
comprising at the thermoforming station a clamping frame with a
recess for connecting points or for a connecting line.
5. The thermoforming system according to claim 1, wherein the
thermoforming system is designed without cooled transverse
bars.
6. The thermoforming station according to claim 1, wherein in the
machine direction, the blank cuts are firmly connected to one
another, either edge to edge or with a slight overlap.
7. The thermoforming station according to claim 1 or claim 2,
wherein in the vertical direction, the blank cuts are connected to
one another in a flexible manner.
8. The thermoforming station according to claim 1, wherein the
blank cuts are connected to one another with a plurality of
connecting points and/or are provided with a connecting line.
9. The thermoforming station according to claim 1, wherein the
blank cuts are glued, sewed, welded together or are mechanically
connected.
10. The thermoforming station according to claim 1, wherein a
forward feed into a first clamping frame position takes place so
that a clamping frame closes on a joint of the two blank cuts.
11. The thermoforming station according to claim 1, wherein the
blank cuts are provided with the length of a clamping frame so that
the clamping frame closes at a first and at a second position on
both joints of three blank cuts.
12. The thermoforming station according to claim 1, wherein blank
cuts from different materials are fed.
13. The thermoforming station according to claim 1, wherein blank
cuts with different colors are fed.
14. The thermoforming station according to claim 1, wherein in
dependence of the requested blank cut, a system program is varied,
in particular a heat output is varied.
15. The thermoforming system according to claim 1, wherein hot melt
is applied onto the film strip.
16. The thermoforming system according to claim 1, wherein the
different blank cuts are fed from different film rolls, wherein
they are preferably separated into blank cuts at a common
separating station.
17. The thermoforming station according to claim 1, wherein the
method is used for laminating a contour-formed carrier part or for
preforming films, in each case in particular for providing an
interior surface part for a motor vehicle, and primarily by means
of thermoforming or by means of back-injection of the film.
18. Use of a film strip afor processing in a thermoforming system
for producing laminated parts, using the thermoforming station of
claim 1.
19. A thermoforming system according to claim 1, wherein a film
supply station is provided, with a plurality of roll holders for
film rolls, and with a unwind device and a separating device for
preparing the blank cuts.
20. The thermoforming system according to claim 19, wherein the
connecting station is configured for connecting the blank cuts so
as to form a film strip so that the film supply station can be
operated as a dependently or independently operated film strip
production station or system.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application is a divisional of and Applicant claims
priority under 35 U.S.C. .sctn..sctn.120 and 121 of U.S.
application Ser. No. 14/001,706 filed on Sep. 6, 2013, which
application is a national stage application under 35 U.S.C.
.sctn.371 of PCT Application No. PCT/DE2012/000185 filed on Feb.
28, 2012, which claims priority under 35 U.S.C. .sctn.119 from
German Patent Application No. 10 2011 012 617.1 filed on Feb. 28,
2011, the disclosures of each of which are hereby incorporated by
reference. A certified copy of priority German Patent Application
No. 10 2011 012 617.1 is contained in parent U.S. application Ser.
No. 14/001,706. The International Application under PCT article
21(2) was not published in English.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The invention relates to a method for processing two
different thermoplastic films in a thermoforming system, a
thermoforming system set up for carrying out such a method, a film
supply station for the thermoforming system, a film strip, a use
for the film strip, and a laminated part produced therewith.
[0004] 2. Description of the Related Art
[0005] It is generally known and, for example, in the sector of the
automotive supply industry, it is frequently carried out on a daily
basis to mold the surface of a spatial component by means of a
film.
[0006] A common way to do this is the production of laminated
parts. In the course of this, contour-formed parts are covered with
a film. The film is unwound from a roll, fed to a thermoforming
system, heated and subsequently thermoformed over the carrier part
in a forming station, for example by using a vacuum. Thereby,
laminating takes place. An example for this is disclosed in EP 1
521 669 B1.
[0007] An alternative way, which does not require carrier parts, is
subsequent back injection of the film, which in practice is
designated as film preforming.
[0008] During sequential production, thus the production of
different molded parts with sequentially different requirements,
for example in terms of the surface contour or the surface color,
it is necessary to frequently change the film rolls because the
films form the finally visible surface of the finished molding.
Specifically in the automotive industry, many time-consuming roll
changes are required because normally in the targeted sequential
production, frequent changes in the component surface to be
achieved are required.
[0009] Customary products in a motor vehicle can be found primarily
in the interior, for example as dashboards, door panels, instrument
panels, glove compartment, map pocket or cup holder, wherein this
list is not to be understood as being complete.
[0010] In order to avoid many time-consuming film roll changes, no
rolls are used, thus no film strip is used that is continuously
unwound from the film roll. Instead, "blank cuts" are processed.
This means nothing other than that the different film rolls are in
each case separated. A blank cut, thus a piece of film, is
separated from the film roll. At this point it should already be
pointed out that a blank cut can be prepared not necessarily only
by means of a cutting method, but in general by means of any
separating method. However, in practice, cutting has emerged as the
most common method. It is readily conceivable as an alternative to
instead separate the blank cut from the film roll by means of
punching, shearing or flame-cutting or in any other way. What is
important is that a blank cut is obtained, thus such a piece of
film, which is needed for the upcoming processing flow through the
thermoforming system.
[0011] The size of the blank cut is normally kept as small as
possible simply for cost reduction and environmental protection
purposes.
[0012] Specifically in the case of a thermoforming system, usually,
a clamping frame is arranged at the forming station. Within the
forming station, the clamping frame seals film with respect to the
vacuum box. Thus, the size of the clamping frame usually defines
the required size of the blank cut. In particular with regard to
the length of the blank cut, it is therefore intended in practice
not to unnecessarily exceed the length of the clamping frame in the
machine direction.
[0013] The blank cut is placed in the transport means that is
generally available in a thermoforming system. The transport means
are formed in most cases by pairs of belts, usually chain-driven,
with needles, clips or cards, or by other transport chains. The
transport means holds the blank cut placed thereon on both sides at
the film edges and transports it in this manner through the
thermoforming system.
[0014] Since generally a heating station is available, and the
thermoforming system as such effects in any case heat irradiation
onto the film, the blank cut needs to be additionally held on the
infeed and outfeed sides with cooled transverse clamping bars so as
to avoid a concave necking which otherwise would occur due to the
influence of heat.
SUMMARY OF THE INVENTION
[0015] It is an object of the invention to provide a more suitable
way for the sequential production of blank cuts in a thermoforming
system.
[0016] According to a first aspect of the present invention, this
object is achieved by a method for processing two different
thermoplastic films in a thermoforming system, wherein on request
selectively and varying from one film to another one, blank cuts
are brought in a transport means through the thermoforming system
so that different blank cuts are successively transported by the
transport means to a thermoforming station and are processed there,
wherein two successive blank cuts are connected to one another so
as to form a film strip.
[0017] Conceptually, the following should be explained first:
[0018] "Processing" is in particular to be understood as achieving
a semifinished product. It was already explained above that in
particular producing surface-forming parts for the interior of a
motor vehicle is to be envisaged. However, it is also readily
possible to achieve a finished end product within the
processing.
[0019] The "thermoforming system" is a system which plastically
deforms the incoming film by supplying thermal energy.
[0020] The "request" for different parts within the targeted
sequential production can preferably be obtained in real-time from
an order-processing system. It is also conceivable to prepare the
targeted production sequence by means of a statistical system,
thus, for example, to request the different films in conformity
with usual order rates, and to produce therewith the different
surfaces. In the former case, stock-keeping can be completely
dispensed with as long as it is provided that the parts produced in
the thermoforming system are subsequently transferred immediately
to the next production step. In the second case it is to be
expected that an insignificant inventory of finished parts from the
thermoforming system will form.
[0021] "Varying from one the film or the other film" is to be
understood such that not necessarily only the one film or the other
film shall be used, but that according to the production sequence,
changes can occur that do not have to be predictable by the
thermoforming system. However, the concept includes productions in
which not always a change of the film type from blank cut to blank
cut is required. It is readily possible that two or more blank cuts
from the same film are successively prepared and processed.
However, the invention exploits its advantage in particular exactly
when a change of the film type takes place between two successive
blank cuts.
[0022] If "two different films" are spoken of, this is not to be
understood as being limited in the meaning of "exactly two", but is
to be understood in the meaning of an "at least two"
indication.
[0023] The same applies analogously within the context of the
entire application present here: Indefinite articles or numerical
data are in each case to be understood as "at least" indications
unless it is clear from the context at a certain point that only an
"exactly" indication is to be understood there.
[0024] The idea of the first inventive aspect is to connect two
successive blank cuts in a thermoforming sequence to one another so
as to form a film strip.
[0025] A "film strip" is such a strip that is longer than the blank
cut preceding or succeeding the joint. To the length of the blank
cut, viewed in the machine direction, thus along the transport
direction through the thermoforming system, a further blank cut is
fixed.
[0026] It is then no longer necessary to hold the transition from a
first blank cut of a first film to a second blank cut of a second
film at the heating station with the cooled transverse clamping
bars. Rather, the two blank cuts connected to one another as a film
strip mutually stabilize one another at their connected front ends.
Since normally the film strip is held on the right and on the left
at its edges anyway, for example with a needle chain, undesired
necking of the film within the heating station is therefore not to
be expected.
[0027] In particular, the presented inventive aspect has recognized
that the transverse clamping bars, even with only a small width,
still make additional waste practically unavoidable because the
width of the blank cuts underneath the transverse clamping bar
cannot be processed. The film region clamped by the transverse
clamping bar thus increases the film consumption without being able
to process the film used up through this so as to form the
product.
[0028] Therefore, when carrying out the method, low film
consumption can be achieved.
[0029] Preferably, the blank cuts are firmly fastened to one
another, either edge to edge or with an overlap. When fastened edge
to edge, thus front end against front end, maximum material savings
can be achieved. In the case of an overlap of preferably only a few
millimeters, connecting the two blank cuts is generally easier to
carry out.
[0030] It is proposed that the blank cuts and/or the film strip are
stretched within the process. Stretching serves, for example, for
utilizing the film more efficiently because starting with a film
delivered on a roll, the film thickness in the longitudinal
direction and in the transverse direction can be reduced by
stretching, and the surface area to be processed can be increased.
Stretching in the longitudinal and transverse directions can be
found, for example, in DE 101 13 524 B4 or again in DE 10 2006 048
296 A1.
[0031] Stretching can be performed on the blank cut before it is
connected to form a film strip for further processing in the
thermoforming system.
[0032] However, it is preferably intended to first prepare the film
strip by connecting the successive blank cuts and then to stretch
the resulting film strip in the longitudinal and/or transverse
direction. This places higher requirements on the strength of the
connection of the blank cuts; however, it saves new system
constructions.
[0033] In the vertical direction, in any case approximately in that
direction which is perpendicular to the machine direction and to
the film plane within the system, attaching the blank cuts to one
another preferably takes place in a flexible manner. This means
that in the connected region of the two successive blank cuts, no
excessive stiffening needs to take place there as this would have
been the case, for example, when clamping using a transverse
clamping bar in the heating station. Rather, it seems advisable to
leave the film substantially to itself and to its sag. In fact,
when heating up the film within the thermoforming system, the film
becomes softer and a certain sag occurs between the transport means
at both edges of the film. This sag has already been addressed in
the prior art by proven compensation means, for example by
transverse stretching. This is usually achieved through divergently
running conveyor belts. Thus, if the film is not excessively
stiffened at its joint or overlapping edge of successive blank
cuts, but is substantially left to its free sagging flexibility,
this can be advantageous from a system point of view.
[0034] The blank cuts can be connected to one another with
connecting points and/or can be provided with a connecting line.
This means that at their front ends facing one another, the blank
cuts are connected to one another with a plurality of discrete
connecting points or with a track-like connection, wherein the
latter does not necessarily have to extend in a straight line, but
can deviate from a straight course. In particular, two or more
point rows that are offset to one another are possible for
connecting, or two or more lines that are offset to one another. It
is generally preferred that the connection points are oriented
rather transverse to the machine direction, preferably
perpendicular to the machine direction. It is then still
particularly easy to deflect the film in the system.
[0035] For connecting the successive blank cuts to one another, in
particular glueing, sewing, welding and/or another mechanical
connecting process can be considered, for example by using a
connecting part such as a connecting strip, adhesive strip, a clamp
or the like.
[0036] In a particularly preferred embodiment of the invention, the
connected region of two successive blank cuts are fed exactly to a
first clamping frame position so that a clamping frame closes on a
joint of the two blank cuts.
[0037] In view of the above, the clamping frame can in particular
close on a connecting line or on connecting points and/or on an
overlap region of two blank cuts.
[0038] The general idea here is that the clamping frame itself,
thus the component for ensuring the thermoforming (vacuum)
pressure, has a certain overall width. The clamping frame generally
consists of an upper part and a lower part, which close against one
another. The film is clamped over the clamping frame width in the
forming station and cannot participate in the formation of the
product. Thus, the film area clamped in the clamping frame cannot
be avoided as waste anyway.
[0039] It is useful if exactly the transition edge between the
successive and normally different films is used as this unavoidable
waste since the transition is likewise waste anyway.
[0040] Preferably, the blank cuts, or at least a portion of the
blank cuts, are provided with the average length (averaged from
inner and outer lengths) of the clamping frame so that the clamping
frame closes not only at a first, infeed-side clamping frame
position on the on the joint of two blank cuts, but in addition
also at a second, outfeed-side clamping frame position on a joint
of the preceding one of the two blank cuts with the third blank
cut.
[0041] In simple words, the clamping frame which seals the film
with respect to the vacuum box is not avoided in such an
embodiment. Rather, it is used in a proven manner in the
thermoforming system although it requires a certain constructional
width which increases the film consumption. However, the film
transport is controlled or regulated in such a manner that with
each machine cycle, the seam of the blank cuts is positioned in
alignment with the clamping frame.
[0042] It is then possible to use proven technology again because
the film strip joined together from the blank cuts forms a
continuous strip again which does not require cooled transverse
bars or other deviations from conventional single-strip
systems.
[0043] With regard to the different blank cuts it is in particular
envisaged that they can consist of different materials, can
comprise different materials and/or can have different colors.
[0044] It is proposed that a system program is varied depending on
the requested blank cut. Today's systems are normally at least
controlled, in most cases even feedback-controlled. The feedback
control concerns, for example, the stretching of the film strip in
the transverse direction, the stretching of the film strip in the
longitudinal direction, the temperature and the distance of the
radiant heaters from the film strip, the thermoforming pressure,
the residence time in the heating station or in the molding tool.
All parameters can be individually optimized for each blank
cut.
[0045] A system control can be set up in such a manner that it
recognizes if two poorly combinable blank cuts are successively
requested or are in any case still within the thermoforming system
so that they are subjected to the same machine cycle. The control
of the thermoforming system can receive a pool of requests and
preferably processes them successively in the technically best
manner, independently of the concrete input sequence of the
requests.
[0046] In a particularly simple and nevertheless reliable form of
connection of two successive blank cuts, an adhesive can be applied
on the film strip.
[0047] In a particular constellation, hot glue, so called "hot
melt" could also be used as an adhesive.
[0048] Hot melt is applied in the hot state onto the intended
bonding area and when cooling down, it establishes the bond. Thus,
it is in particular envisaged to apply hot melt for other purposes
at suitable places onto the film strip, either onto the blank cuts
prior to connecting them, or onto the already connected film strip.
Hot melt application is very well suited for improving adhesion on
certain laminating carriers. For laminating side panels in the
motor vehicle interior, for example, hot melt application is
considered to be useful.
[0049] The hot melt can already be applied when preparing the film
strip or only when feeding it into the thermoforming system,
preferably upstream of a heating station.
[0050] In a preferred configuration of the method it is proposed
that the different blank cuts are fed from different rolls, wherein
they are preferably separated into blank cuts at a common
separating station.
[0051] The different films are normally delivered on different film
rolls. Ideally, they are provided alternatively accessible in a
common support frame. One or more roll-off units can be provided so
as to unwind the films from the rolls.
[0052] Preferably, there is only a single separating station which
separates the different films unwound from the rolls into the
different blank cuts.
[0053] Preferably, connecting the successive blank cuts so as to
form a film strip is carried out directly at the separating station
or on the outfeed side of the separating station. For example,
separating the rear end edge of a blank cut can take place
simultaneously with connecting the front end edge of the same blank
cut to the preceding blank cut which preferably is already at least
partially held in place in the transport device of a thermoforming
system that begins there.
[0054] It has already been mentioned that the method can ideally be
used for laminating a contour-formed carrier part or for preforming
films, in each case in particular for providing an interior surface
part for a motor vehicle.
[0055] As the actual forming technology, thermoforming or back
injection is preferably to be considered.
[0056] According to a second aspect of the present invention, the
given object is achieved by a thermoforming system which is
suitable and set up for carrying out the above-described method at
least in partial aspects, wherein the thermoforming system has a
thermoforming station for processing the different films, further
has transport means for transporting the film to the thermoforming
station, and in addition a connecting station for connecting
successive blank cuts so as to form a film strip.
[0057] It has already been conceptually explained that the
"connecting station" can be either a separate station or can belong
to the system especially within the transfer through the
thermoforming system.
[0058] However, the connecting station is preferably combined with
other stations, for example combined with a hot melt station,
and/or is combined with a separating station because only from the
separating station onward are there individual blank cuts available
which then are to be connected to one another. It makes sense to
carry this out as fast as possible, thus in particular even before
a possible stretching in the longitudinal direction and/or in the
transverse direction takes place. The separating station does not
have to be part of the actual thermoforming system. Rather, the
separating station can be operated arranged in spatially separated
manner.
[0059] The thermoforming system in its broader sense, thus
including the roll holders, the separating station and the
connecting station, preferably comprises a plurality of different
film rolls, in particular with an unwind device and a separating
device for preparing the blank cuts.
[0060] The thermoforming system and/or a separate film strip
production system can comprise a controller which is set up for
processing a request for a certain film and thereupon controls a
film, in particular a film roll, so that a blank cut is prepared
therefrom and is connected to an adjacent blank cut so as to form a
film strip.
[0061] As already explained, the request can be processed in the
sequence in which it was received. One variant is that from certain
requests which can be received, only a sub-selection is accepted.
Thus, for example, when producing parts for the automotive supply
sector, a total of n different colors, structures or materials can
be selected and thus can be sent as request to the thermoforming
system wherein, however, the thermoforming system can only receive
m different film rolls at the same time ready to be delivered to
the transport system to the thermoforming station, so that the m
currently loaded films are processed immediately upon request,
whereas requests for the n-m remaining variants of films are
initially deferred. For example, a maximum limit value for waiting
orders can be permitted.
[0062] Preferably, changing a film is carried by means of the film
roll while other films are still accessible by the thermoforming
system. Thus, for example, it is signalized to the system, or the
system signalizes to the user, that of the three film rolls A, B, C
available in a common supply shelf, exactly one roll, namely the
roll A is now to be replaced by a different roll D or by a
replacement roll A'. Nevertheless, the system can still continue to
work. During the changeover time, the system only processes
requests for the films B and C. The requests for A or D or further
film types accruing in the meantime are stacked and subsequently
processed.
[0063] The thermoforming system preferably comprises in a
conventional manner a clamping frame at the thermoforming station.
In a particular configuration, said clamping frame can have a
recess for connecting points or for a connecting line, thus a
point- or line-shaped recess in which a bulge can press in, namely
a bulge that occurred as part of the connecting process of the two
adjacent blank cuts. The vacuum can then be established with proven
reliability.
[0064] It is proposed that the thermoforming system is designed
without cooled transverse bars which, for instance, would be
transported through the system with joints of two adjacent blank
cuts.
[0065] According to a third aspect of the present invention, the
object is achieved by a film supply station for the above-described
thermoforming system, with a plurality of roll holders for an equal
plurality of film rolls, with an unwinding device and with a
separating device for preparing the blank cuts. Preferably, a
connecting station is also integrated in this structural unit,
primarily at the separating device.
[0066] According to a fourth aspect of the present invention, the
object is achieved by a film strip for industrially processing in a
thermoforming system for laminating carrier parts or for preforming
films, which film strip is joined together in the longitudinal
direction from blank cuts of different films, wherein the blank
cuts are connected to one another in a tensile-stress-resistant
manner.
[0067] It is explicitly pointed out that such a film strip is
present not only upstream of the molding tool, but, depending on
the kind of cut-out, normally also in the form of a film grid
downstream of the forming station. In the feeding system to the
molding tool, the assembled film strip is easier to handle, saves
film because the transverse clamping bars in the heating station
are no longer required, and guarantees fast production on a high
quality level. However, handling downstream of the molding tool, in
the film grid, is very easy as well. If the entire film grid can be
disposed of in a uniform way, it can be coiled in simple manner,
for example.
[0068] If the remaining grid is to be disposed of in a different
manner, for example because materials were used which are to be
disposed of differently and which are connected to one another so
as to form a film strip, then it is proposed to separate them
accordingly downstream of the molding tool.
[0069] It is to be understood that the advantages of the
aforementioned inventive aspects also have a direct advantageous
effect on the laminated part produced in this manner.
BRIEF DESCRIPTION OF THE DRAWINGS
[0070] The invention is explained in more detail hereinafter based
on exemplary embodiments with reference to the drawing. In the
figures:
[0071] FIG. 1 shows schematically a top view of three film rolls
with different films and with blank cuts separated therefrom,
[0072] FIG. 2 shows schematically a top view of three different
blank cuts of the three film rolls from FIG. 1 that are connected
to one another so as to form a film strip, being fed into a
thermoforming station,
[0073] FIG. 3 shows schematically a side view of a molding tool
with a clamping frame located thereabove and a film strip running
therein,
[0074] FIG. 4 shows the illustration from FIG. 3 with blank cuts of
the film strip drawn in an exploded view,
[0075] FIG. 5 shows schematically the detail from FIG. 4,
[0076] FIG. 6 shows schematically a top view of a piece of film
strip with three blank cuts and two connecting regions with an
overlap,
[0077] FIG. 7 shows the piece of film strip from FIG. 6 with a
clamping frame top located thereabove,
[0078] FIG. 8 shows schematically a side view of three film rolls
with different films, a cutting device and a thermoforming
system,
[0079] FIG. 9 shows the arrangement from FIG. 8 with a film piece
that is pulled out, and a cutting knife in engagement, and
[0080] FIG. 10 shows the arrangement from the FIGS. 8 and 9 with
schematic illustrations of a plurality of produced blank cuts.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
[0081] The three film rolls 1, 2, 3 in FIG. 1 are each mounted to
be rotatable about a roll axis 4. Unwound therefrom are three
pieces of film strip 5, 6, 7. The first film strip 5 consists of a
first film type F1. The second film strip 6 consists of a second
film type F2. The third film strip consists of a third film type
F3. At the front end edges 8 (indicated exemplary) of the film
strips 5, 6, 7 unrolled from the film rolls 1, 2, 3, three blank
cuts 9, 10, 11 were cut off by a separating device (not
illustrated) by means of clean cuts.
[0082] Like the film strips 5, 6, 7, the three blank cuts 9, 10, 11
consist of different film materials and different film colors of
the film types F1, F2, F3.
[0083] All three film types F1, F2, F3 are thermoplastically
deformable in a thermoforming system. They are in particular
suitable to be laminated onto a carrier. The film types F1, F2, F3
can be, for example, a differently colored synthetic material with
a grained leather-like look, or they can be smooth films onto
which, for example, a leather-like grain is embossed at a later
time, preferably in-mold in the molding tool.
[0084] When connecting a multiplicity of blank cuts 9, 10, 11 so as
to form a film strip 12, the three blank cuts 9, 10, 11 from FIG. 1
in the present example are adjacent to further blank cuts 13, 14
(numbered exemplary). Overlaps 15, (indicated exemplary) form
connecting regions in which the blank cuts 9, 10, 11, 13, 14 are
firmly connected to one another by means of an adhesive bond, for
example.
[0085] Along a machine direction 17 toward the thermoforming
station 18, the blank cuts 9, 10, 11, 13, 14 of the connecting
region are connected to one another in a tensile-stress-resistant
manner. At lateral edges 170, 180, the assembled film strip 12 is
additionally held by a pair of needle chains (not illustrated).
[0086] The formation of the film strip 12 consisting of the blank
cuts 9, 10, 11, 13, 14 of the film types F1, F2 F3 corresponds to a
sequence to be produced which, for example, was addressed in the
form of a series of in each case individual requests to the
thermoforming system.
[0087] Within the thermoforming station 18, the film strip 12 runs
over a spatially formed laminating carrier 20 (see FIGS. 3 and 4)
within the clamping frame 21. The clamping frame 21 consists of a
clamping frame top 22 and a clamping frame bottom 23.
[0088] For operating the thermoforming station, the clamping frame
top 22 and the clamping frame bottom 23 close against one another.
Thereby, the film strip 12 is firmly clamped along a frame outline
24. The film strip 12 portion located inside the clamping frame 21
can then be very easily drawn onto the laminating carrier 20 by
means of a vacuum, for example through vacuum holes (not
illustrated). In this position, slight cooling takes place after
the film strip 12 was heated up earlier by means of radiant heaters
(not illustrated).
[0089] Thus, in the thermoforming station 25, that portion of the
film strip 12 that is located within the circumferential frame 24
of the clamping frame 21 is laminated onto the laminating carrier
20, and thereby the finished part is produced ready for
installation in a motor vehicle.
[0090] In the exploded view (see FIGS. 4 and 5) it is apparent that
the film strip 12 is originally composed of three different blank
cuts 9, 10, 11 (selected exemplary). In an overlap region 16, a
connection by means of a narrow adhesive tape is arranged
perpendicular to the machine direction 17 over the entire width of
the blank cuts 10, 11. The adhesive tape firmly holds the two blank
cuts 10, 11 together.
[0091] Due to the overlap in the overlap region 16, a bulge of the
film strip 12 with respect to the individual blank cuts 10, 11 can
be found. In order to be able to receive said bulge and still be
able to close the clamping frame 21 in a vacuum-tight manner, in
each case one seam receptacle 25 is situated in the clamping frame
top 22 and in the clamping frame bottom 23, which seam receptacle
extends perpendicular to the machine direction 17 over the entire
width of the film strip 12.
[0092] When the clamping frame 21 closes during the operation of
the thermoforming system, the overlap region 16 of the two blank
cuts 10, 11 is firmly clamped and thus is excluded from processing.
This is exactly what is intended because the overlap region 16 of
the two blank cuts 10, 11 would not have been processible for a
part anyway.
[0093] With each machine cycle, the film strip 12 is therefore
cycled forward by one length of the clamping frame 21, or more
precisely, by the distance between the two centers of the frame
outline 24. By suitably controlling, the overlap regions 15, 16 can
then always be positioned exactly underneath the frame outline 24
of the clamping frame 21 (see in particular FIGS. 6 and 7).
[0094] In the arrangement of the three film rolls R1, R2, R3 in the
FIGS. 8, 9, 10, the three film rolls R1, R2, R3 are placed in a
common film roll shelf. Unwound film strip pieces 31, 32, 33 go to
a common separating station 34. The separating station has in first
instance an upper guide 35 and a lower guide 36 for the film strip
pieces 31, 32, 33. Directly downstream thereof there is a cutting
knife 37. The cutting knife 37 is mounted to be movable; in the
exemplary embodiment shown here it is movable vertically downward
along a cutting direction 38 (cf. FIG. 9).
[0095] In order to obtain individual blank cuts R1', R2' R3' (cf.
FIG. 10) during the operation of the system and for supplying to
the thermoforming station 39, the upper guide 35 and the lower
guide 36 of the separating station 34 can specifically grip a film
strip piece and can unwind it from the roll (here R2) by displacing
it into a downstream position 40. Then, a cut is carried out on the
unwound film strip piece with the cutting knife 37 so that the
blank cuts R1', R2', R3' are obtained from the respective film
rolls R1, R2, R3.
[0096] Subsequently, the blank cuts R1', R2', R3' are connected
(not illustrated in FIG. 10) and reach the thermoforming station 39
only in connected form as a new film strip.
[0097] In the separating station 34, for example, a gripper or
roller system can grip the respective film and unwind it from the
roll.
[0098] The blank cuts are either connected or transported
individually into the thermoforming system and are processed
therein.
[0099] In other words, a conceivable system concept comprises that
prefabricated film cuts in all needed colors or structures are
placed by means of a device into a connecting station, which is
arranged upstream of the film infeed, in such a manner that they
are either connected edge to edge or transversely with a slight
overlap. For connecting, for example, high-frequency welding,
thermal contact welding, adhesive and further connecting means can
be considered.
[0100] The position should be selected such that the joint is
always positioned underneath the transverse bar of the clamping
frame.
[0101] Thereby, a continuous film with different colors is obtained
which can be processed with little material loss.
[0102] If necessary, automatic adjustment of the heater in the
system should take place for different colors or structures.
[0103] For processing the different colors, conventional laminating
stations and, in general, thermoforming system can be used. The
system not even "recognizes" that the incoming film strip is
composed of individual blank cuts.
[0104] Upstream of the film infeed, a film star can be arranged for
different colors or structures, thus, in general, for the different
film types.
[0105] For example, in each case one film is cut to size and is
placed onto the connecting station and is connected.
[0106] Upstream of the film infeed, a device can be provided onto
which the blank cuts are placed so that the newly unwound film is
positioned either edge to edge or slightly overlapping with the
preceding blank cut. Onto this device, a device for connecting the
film is mounted which is adjustable in terms of the blank cut
length.
[0107] In the case of a plurality of cycles with the same color,
preferably, the films are connected to the last blank cut and only
cut again to the exact length if a sufficiently long film strip
piece is unwound from the film roll so as to process the planned
cycles. Thus, in this case too, a blank cut is obtained that is
connected to a preceding blank cut, but with the difference that in
this case, the blank cuts do not have the same length.
[0108] If hot melt is applied, preferably, an inline hot melt
application system can be positioned between the connecting station
and the thermoforming station. Advantageously, time independence of
the processing time of the hot melt is achieved in this manner.
Moreover, positioning problems in the connecting station are
prevented because after the hot melt application, the ends of the
film can considerably curve upward.
[0109] In simple words, it is therefore preferred that hot melt is
only applied if the blank cuts are already connected to form a film
strip.
[0110] The devices for fabricating the film strip composed of blank
cuts can be operated completely separate from the laminating
system. The sequential film strip can even be purchased from a
separate company.
[0111] Apart from that, with suitable film cuts there is the
possibility to process even a two-colored film in the thermoforming
station.
* * * * *