U.S. patent application number 09/949995 was filed with the patent office on 2003-03-13 for method and device for packaging objects in a weldable film.
Invention is credited to Kaechele, Klaus, Kallfass, Jens.
Application Number | 20030046905 09/949995 |
Document ID | / |
Family ID | 25489806 |
Filed Date | 2003-03-13 |
United States Patent
Application |
20030046905 |
Kind Code |
A1 |
Kaechele, Klaus ; et
al. |
March 13, 2003 |
Method and device for packaging objects in a weldable film
Abstract
In a sealing/parting means for the side weld (42) of a film
semi-tube (13) of shrink film, in which items (16) are wrapped, the
film web (19) consisting of two sandwiched films is fed to a
transport and supporting system (18) comprising two opposing
transport belts (21, 22) where it runs along an elongated,
skid-shaped contact surface area (34) of a heated sealing/parting
knife (20), resulting in the immediate welding zone of the film
being preheated before it is fed at the end of this contact surface
area to a sealing/parting blade (36) which parts and welds the
film. The sealing/parting blade (36) has a constricting cutting
gap.
Inventors: |
Kaechele, Klaus; (Huelben,
DE) ; Kallfass, Jens; (Nuertingen, DE) |
Correspondence
Address: |
NATH & ASSOCIATES PLLC
1030 15th Street NW - 6th Floor
Washington
DC
20005
US
|
Family ID: |
25489806 |
Appl. No.: |
09/949995 |
Filed: |
September 12, 2001 |
Current U.S.
Class: |
53/459 ;
53/568 |
Current CPC
Class: |
B29C 66/836 20130101;
B65B 51/26 20130101; B29C 66/1122 20130101; B29C 65/305 20130101;
B29C 66/83413 20130101; B29C 65/7894 20130101; B29C 66/91231
20130101; B29C 66/4322 20130101; B29C 66/91431 20130101; B65B
61/005 20130101; B29C 65/18 20130101; B29C 66/91421 20130101; B65B
61/10 20130101; B29C 65/749 20130101; B29C 66/961 20130101; B29C
65/7439 20130101; B29C 66/0242 20130101; B65B 9/067 20130101; B29C
66/8167 20130101; B29C 66/91212 20130101; B29C 66/73715 20130101;
B29C 66/7352 20130101 |
Class at
Publication: |
53/459 ;
53/568 |
International
Class: |
B65B 009/06 |
Claims
1. A method of packaging items (14) by means of a weldable film
(19) in which the film is transported relative to a sealing/parting
device (12) in a film transport direction (17) comprising the steps
of feeding the film (19) to said sealing/parting device (12) in at
least two plies, preheating an area of the film in said
sealing/parting device (12) in a preheating zone (34) of said
sealing/parting device, subsequently parting said film by means of
a heated sealing/parting blade (36) in said preheated film area,
thereby creating heated parted edges of the film, and thus
simultaneously welding at least two of the plies at the parted
edges.
2. The method as set forth in claim 1 wherein said film area is
preheated by contact heat transfer in said preheating zone.
3. The method as set forth in claim 1, wherein said film area is a
narrow, longitudinal area of the restricted to immediate vicinity
of said cut portion.
4. The method as set forth in claim 1, wherein preheating is
undertaken in a preheating zone (34) oriented elongated in said
film transport direction (17).
5. The method as set forth in claim 1, wherein said film (19) is a
polyolefine film.
6. The method as set forth in claim 6, wherein said film (19) is a
shrink film between 30 and 120 .quadrature.m thick of the kind as
marketed by SEALED AIR CORP. CRYOVAC, Rodgers Bridge Road, Building
A, Duncan, SC 129334-0464, U.S.A. designated ,,CorTuff".
7. A device for packaging items (14) by means of a weldable film
(19) comprising a film transport (16,18), with which said film is
transported in a transport direction (17) relative to a
sealing/parting device (12), said film (19) includes, when passing
said sealing/parting device (12), at least two layers, said
sealing/parting device (12) comprises a preheating zone (34) and,
following on the preheating zone, a heated sealing/parting blade
(36).
8. The device as set forth in claim 7 wherein of a sealing/parting
knife (20) includes said sealing/parting blade (36) and an
elongated bar (33) having, with regard to the transport direction,
a leading and a tailing end the bar forming said preheating zone,
at which said film (19) is guided along in contact in said film
transport direction (17), the sealing/parting knife (20) being
provided at the tailing end.
9. A heatable sealing/parting knife (20) for a device (11) for
packaging items by means of a weldable film (19), said film being
guided in at least two plies in a film transport direction (17) and
in a film running plane to said sealing/parting knife (20) and
along thereof, resulting in said multi-ply film (19) fed to said
sealing/parting knife (20 being parted and thereby welding at least
two sandwiched film plies to each other, the knife comprising: a
surface portion runmning parallel to said film running plane
including an elongated contact surface area (34) facing said film
running plane, and an adjoining sealing/parting blade (36) crossing
said film running plane.
10. The sealing/parting knife as set forth in claim 9 wherein said
contact surface area has, with reference to said film running
direction, a leading end and a tailing end, and has at its leading
end, an intake rounding (35) and adjoining thereto a straight
strip-type, elongated contact surface area (34) of small size
transversely to said film running direction (17) and wherein said
sealing/parting blade (36) as compared to said contact surface area
portion is short and has a cutting edge (38).
11. The sealing/parting knife as set forth in claim 9, wherein said
sealing/parting blade (36) together with said contact surface area
(34) forms a constricting intake gap (37).
12. The sealing/parting knife as set forth in claim 9, wherein said
contact surface area is between 2 mm and 4 mm wide and 50 mm to 100
mm long.
13. The sealing/parting knife as set forth in claim 9 in which a
heater (31) and a temperature sensor (32) are integrated.
Description
BACKGROUND OF THE INVENTION
[0001] The invention relates to a method and a device for packaging
items by means of a weldable film and to a sealing/parting knife
therefor. It is to be noted that the terms ,,sealing" and
,,welding" as used in the following are synonymous.
[0002] In such packaging machines, items, or stacks thereof, are
wrapped by a usually heat-shrink packaging film which forms a tube
or at least a double-ply running along the the transport direction.
They are subsequently closed off lengthwise and, where necessary,
also crossswise to a weld, the overhang of which is cut off.
[0003] U.S. Pat. No. 5,282,349 shows a sealing/parting means
incorporating a rotating, heatable sealing/parting wheel for
welding the film ply and trimming the overhang, this wheel
cooperating with a companion wheel.
[0004] Known from EP 1 027 981 A (corresponding to U.S. patent
application Ser. No. 09/500,220 of the applicant, filed Feb. 8,
2000), to which reference is made in the following as regards
details of the machine, is one such sealing/parting device
including a sealing/parting wheel.
OBJECT OF THE INVENTION
[0005] The objective of the invention is to improve the
sealing/parting and also to render it useful for films which are
difficultt to weld, as well as providing a device which is
particularly simple and reliable in operation.
SUMMARY OF THE INVENTION
[0006] The invention provides a method in which, instead of a
sealing/parting wheel, a sealing/parting knife is used which is
simple to manufacture and is particularly reliable in operation.
Unlike a wheel including a flexible companion wheel, the
sealing/parting knife works particularly reliably in operation with
no wear. Provided upstream of a sealing/parting blade is a
preheating zone in which the film is preheated, preferably in a
very narrow, strip-type zone, so that when it encounters the
sealing/parting blade it is easily parted, on the one hand, and is
well suited to welding to the adjoining ply, on the other.
[0007] This method also lends itself to satisfactorily working
films very difficult to weld, this applying more particularly to
certain multi-ply polyolefine films relatively thick in part, i.e.
in the range 30 .quadrature.m to 120 .quadrature.m (preferably 60
to 100 .quadrature.m). Such shrink films extruded multi-ply are
marketed by SEALED AIR CORP. CRYOVAC, Rodgers Bridge Road, Building
A-Duncan, SC 129334-0464, U.S.A. designated ,,CorTuff", the
standard version of which ,,CorTuff STANDARD" is 60 .quadrature.m
thick whilst the heavy version of which ,,CorTuff HEAVY" is 100 to
120 .quadrature.m thick.
[0008] These films are exceptionally resistant to tearing and are
employed for packaging stacks of heavy and large items, for
example, construction elements. Welding these films has always been
difficult, which is now corrected by the invention. However, the
invention can be put to use to advantage for other kinds or grades
of film.
[0009] The device comprises a means with which the film is
transported relative to a sealing/parting device in a film
transport direction, preferably continuously or also
discontinuously. The sealing/parting device comprises a preheating
zone, followed by a heated sealing/parting blade. Preheating zone
and sealing/parting blade may be combined in a common, heatable
sealing/parting knife comprising an elongated narrow surface
portion running parallel to the running plane of the film at which
the film is guided along with contact so that it is heated by
contact heat.
[0010] Directly adjoining the latter and heated together therewith
the sealing/parting blade may be provided. It crosses the film ply
and may form a intake gap formed, on the one hand, by the contact
surface area and, on the other, by a protruding blade section, the
intake gap protruding under the film ply like the bulbous bow of a
ship, as a result of which the film is reliably guided into the
cutting zone of the sealing/parting knife. The complete
sealing/parting knife is either clamped in a heated support or,
preferably, it has an integrated heater and a control sensor. These
may be accommodated in corresponding drillings adjoining the
working zones formed by the contact surface area and the film
welding knife. The sealing/parting means is suited to particular
advantage for substantially continuous production of a side weld of
a film semi-tube of a shrink film, but is just as suitable also for
other applications, e.g. for welding film webs on both sides,
etc.
[0011] Details of the film is transport and guide in the
sealing/parting zone can be taken from the patent publication EP 1
027 981 A of the applicant as cited at the outset to which express
reference is made in the present specification.
[0012] These and further features are evident not only from the
claims but also from the description and drawings, each of the
features being achieved singly or in combination in the form of
sub-combinations in one embodiment of the invention and in other
fields and which may represent advantageous aspects deserving
protection in their own right as claimed in the present. It is
understood that sub-dividing the application into individual
sections as well as intermediate titles does not restrict the
claims made therein in their general application.
BRIEF DESCRIPTION OF THE DRAWINGS
[0013] An example embodiment of the invention will now be detained
with reference to the drawing in which:
[0014] FIG. 1 is a diagrammatic view in perspective of part of a
packaging machine including a sealing/parting device,
[0015] FIG. 2 is a side view of the sealing/parting device
including the corresponding transporting system.
[0016] FIG. 3 is a side view on a magnified scale of a
sealing/parting knife,
[0017] FIG. 4 is a front view of the sealing/parting knife and
[0018] FIG. 5 is a further section on a magnified scale taken along
the line V-V as shown in FIG. 3
DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT
[0019] Referring now to FIG. 1 there is illustrated, as part of a
packaging machine 11, a side sealing/parting means 12 for the
purpose of closing off on one side a film semi-tube 13 in which the
items 14, for example books, boxes, but also larger and heavier
parts such as doors, windows or the like are to be packaged as
described in general U.S. Pat. No. 5,799,470 A to which express
reference is made as regards the device for folding the tube 13 and
for inserting the items. The film semi-tube 13 thus consists of a
web of film longitudinally folded roughly in the middle in which
the items are located spaced away from each other. The side
sealing/parting means 12 serves to produce a tube from this film
semi-tube in which the two webs of film located one on the other,
are welded together with simultaneous parting and removal of the
waste overhang 15. The film used in this case is preferably the
relatively thick polyolefine film as described previously.
[0020] The items are transported on a transport belt or a table
substantially continuously in the transport direction 17.
[0021] The side sealing/parting means 12 contains, as evident from
FIGS. 1 and 2, its own transport and supporting system 18, the
speed of which is synchronized to that of the transport belt, the
transport and supporting system 18 feeding the film webs 19 pressed
together into a sealing/parting knife 20 and subsequently thereto
to the welding zone over a certain distance.
[0022] The transport and supporting system 18 consists of two sets,
each consisting of two endless transport belts 21, 22, which are
synchronized via meshing gearwheels 23 on their drive and guide
rollers 51, 52, 53. Each set of transport belts consists of two
belts guided parallel to each other, forming a gap 50 inbetween in
which sealing/parting is done, i.e. the film webs are guided
tensioned on both sides of the later weld. Each transport belt runs
over two rollers 52, 53 at the input end and the drive roller 51
driven by the gearwheel 23 so that it has a triangular path, within
which, space is provided for the sealing/parting tool.
[0023] The lower reach 24 of the upper transport belt 21 and the
upper reach 25 of the lower transport belt 22 run in contact with
each other, separated only by the film webs located inbetween, and
are guided, where necessary, via slide rails 26. Before the film
enters the side sealing/parting means it passes through an intake
roller pair 27. These transport means are synchronized in transport
direction and speed with the transport belt.
[0024] The double-ply film web 19 guided between the belts 21, 22
is fed in a film running plane 54 to the sealing/parting knife 20
arranged in the region of the parallel guide afforded by the
reaches 24, 25. The sealing/parting knife 20 is releasably and
replacably clamped in a support 28 and consists of a metal body as
evident more particularly from FIGS. 4 to 5. Near the tensioning
tabs 29 and in the region of a relatively massive base body 30,
which is elongated in the transport direction, there is an
electrical heater cartridge 31 accommodated in a horizontal
longitudinal drilling. The cartridge serves to heat the
sealing/parting knife and is maintained at a preset temperature by
a controller (not shown) for setting to the required temperature as
detected by a temperature sensor 32 accommodated in a drilling of
the base body 30 parallel to the heater cartridge.
[0025] Adjoining the base body 30, offset to one side thereof, is a
relatively narrow skid-shaped contact bar 33 transversely to the
transport direction including a narrow and elongated contact
surface area facing the film web, comprising in the intake region a
rounding 35. At its elongated side edges the contact surface area
is provided with a chamfer 36 (FIG. 4) or a radius, it preferably
being configured straight and parallel to the transport direction
17, but may also be configured curved.
[0026] The contact surface area is roughly 3 mm (between 2 and 4
mm) wide and has a length of 50 to 100 mm along which the
sandwiched film webs 19 run in contact therewith.
[0027] Provided at the end of the contact surface area, i.e. after
the film webs 19 have run along the majority of the contact surface
area, is a sealing/parting blade 36 incorporating the
sealing/parting knife preferably formed as a single piece of metal.
As compared to the contact surface area this sealing/parting blade
is relatively short (roughly 10 to 15 mm in the direction of the
film), it crossing the film web 19 and forming with the contact
surface area a constricting intake gap 37 becoming narrower in the
transport direction and formed so that the contact surface area
also in this portion is still able to pass through substantially in
a straight line. This is why the sealing/parting blade 36, although
sharpened to an edge at the front, has the shape of a bulbuous bow
in the side view so that the film is maintained, in any case, in
its predefined film running plane. Reference is expressly made to
the Figures, especially to FIGS. 3 to 5. as regards details in
configuring the sealing/parting knife and more particularly the
sealing/parting blade.
Function
[0028] The items wrapped in the film semi-tube 13 are run, together
therewith, past the side sealing/parting means in the film running
plane 54 preferably continuously at constant speed, the side
sealing/parting means feeding the films tensioned between the
transport and supporting belts 21, 22 to the sealing/parting knife
which is heated to a temperature permitting sealing/parting as a
function of the nature of the film, its thickness etc., more
particularly as a function of the melting response of the film as
well as of the intake speed of the film. The film enters the zone
of the sealing/parting knife 20 in the region of the intake
rounding 35 and in contact with and along the elongated narrow
contact surface area 34, resulting in the film being uniformly
preheated but restricted to the portion of the later
sealing/parting seam, i.e. the useful width of the contact surface
area, after deduction of the rounding or chamfer, constituting the
welding zone which is only few millimeter wide as guided in the gap
50.
[0029] When the film attains the sealing/parting blade 36, the two
film webs 19 are parted, whereby welding of the film webs usually
takes place already beforehand to a certain degree. In any case,
however, the two film webs are welded together downstream of the
sealing/parting blade 36, as prompted by the constricting shape of
the intake gap as well as by the side guide surfaces 39 of the
sealing/parting blade (see more particularly FIGS. 3 and 5)
subsequently configured as a wedge-shaped constriction. The film
material preheated by the contact heat transfer mainly in the
welding zone and thus softened is, after having been parted, urged
slightly apart by the thickness of the sealing/parting blade which
may correspond at the rear end 40 to that of the contact bar 33,
whilst simultaneously being concentrated from above and below to
thus enable a reliable weld to be formed.
[0030] The film waste strip 15, likewise welded in this action and
likewise consisting of two plies of film, is removed by vaccuum 40
(FIG. 1), although, of course, instead of vacuum removal a reeler
could be used just as well.
[0031] Trials have indicated that with this film sealing/parting
knife films can also be satisfactorily welded which hitherto were
unweldable satisfactorily with other knives or sealing/parting
wheels. The reason for this is, on the one hand, the reliable film
intake, as assured by the contact rail, to the actual
sealing/parting blade, and on the other, by the preheating being
restricted particularly to the direct parting site. This is assured
by the contact transfer in the region of the contact surface area
34 whose width substantially corresponds to the width as furnished
by the material for the sealing/parting weld.
[0032] Once the weld 42 has been produced and thus the film
semi-tube 13 created, the latter is fed with the items to a cross
welding means which undertakes a sealing/parting action in the
interspaces 43 between the items to totally wrap the item and to
separate each individual packaged item from the other. After this,
the items are run into a shrink tunnel in which the shrink film, of
which the packaging mostly consists, is shrunk tight about the
items by heating. Because of the forces materializing thereby, it
is essential that the weld or sealing seams are resistant to
tensile stress and uninterrupted.
* * * * *