The invention relates to a device for forming a bottom opening between bag
sections at the open end region of a tubular bag body, with a transport device for
transporting the bag body in a transport direction transverse to its longitudinal
extension, and with an opening device for forming the bottom opening between
the bag sections at the open end region of the tubular bag body, wherein t5 he
opening device comprises a preliminary opening station, with which the bag
sections at the open end region of the tubular bag body can be transferred from a
state lying flat one upon the other into a state spaced apart from one another,
wherein the opening device comprises at least one splaying element rotatable
10 about a rotary axis, which splaying element can be introduced during rotation
between the bag sections at the open end region of the tubular bag body, wherein
the rotatable splaying element comprises a wedge element with at least one wedge
surface ascending against the direction of rotation, with which wedge surface the
bag sections at the open end region of the tubular bag body can be splayed apart
15 during its transport on the transport device, in order to form the bottom opening
between the bag sections at the open end region of the tubular bag body.
Furthermore, the invention relates to a method for forming a bottom opening
between bag sections at the open end region of a tubular bag body, wherein the bag
20 body is transported in a transport direction transverse to its longitudinal extension
and, during transport, a bottom opening between the bag sections at the open end
region of the tubular bag body is formed, wherein the bag sections at the open end
3
region of the tubular bag body are transferred in a preliminary opening station from
a state lying flat one upon the other into a state spaced apart from one another.
Plants for producing bags have long been known in the prior art. These plants
comprise the provision of material tubes, which have been obtained either 5 by
producing tubular material webs or by joining together the longitudinal edges of flat
material webs to form a tubular structure, the cutting of the material tubes to form
tubular bag bodies of suitable length and the formation of a bag bottom by suitably
opening, folding over and closing an open end of the tubular bag body. Various
10 solutions have been proposed in the prior art for the opening of the bag bottom.
A device for pulling open cross bottoms on a paper tube is known from DE 640
287 C, wherein the two tube layers of a tube section are separated from one
another with the aid of a separating finger. As the tube moves onwards, a single
15 splaying disc passes between the two tube layers, the shell of which splaying disc
widens from a tip to a widening wedge. The splaying disc thus penetrates, during
rotation, ever deeper into the two enveloping layers of the tube, as a result of
which the tube bottom is splayed apart uniformly. In order to enable the
penetration of the splaying disc between the tube layers, a conventional separating
20 finger is provided in this embodiment.
On the other hand, DE 1 611 701 discloses a device for opening the ends of
transversely conveyed flat-lying tube pieces in the production of the cross bottoms
4
of bags and sacks in bottoming machines. In a variant of embodiment for
continuously operating bottoming machines, tube sections are conveyed past
various processing stations in a transverse position by means of a surrounding
gripper chain. A stationary pair of suction boxes, which comprises rows of suction
holes, is provided for opening the tube bottom. The suction boxes are connecte5 d
by pipelines to a vacuum pump. The suction boxes are disposed diverging only by
a few millimetres in the transport direction. The known embodiment is not
intended or suitable for enabling the penetration of a splaying disc or suchlike
between the tube layers. On the contrary, the carrier plate in the prior art
10 comprises on the one hand a compressed air nozzle, the air flow whereof is
directed into the air gap between the two film layers. On the other hand, two
further counter-rotating pairs of suction boxes are required, with which the pulling
open and laying of the cross bottom is carried out.
15 A bottoming device for cross bottom bag machines is known from DE 912 045,
wherein a crescent-like bottoming element is provided, which can be moved into a
pre-opened tube end. The crescent-like bottoming element rotates about a swivel
pin, which is fitted rotatably to a lever arm of a rotatably mounted double lever.
The lever arm is controlled by means of a cam via a connecting rod provided with
20 articulated joints at its ends and a double lever with a roller. As a result of the
swivelling of the swivel pin of the bottoming element about the pivotal centre, the
bottoming element performs a swivelling motion apart from the rotary motion
brought about by gearwheels.
5
However, this embodiment is disadvantageously unreliable, since the crescent-like
bottoming element cannot always ensure a sufficient bottom opening.
Malfunctions can thus arise in the prior art, which can lead to operational failures.
Moreover, the mounting of the bottoming element is comparatively complex.
5
Different kinds of device for opening tube bottoms are known for example from
WO 2012/049040 or AT 406 755 B.
In contrast with this, the problem of the present invention consists in providing a
10 device and a method for forming a bottom opening, such as mentioned at the
outset, which mitigates or eliminates the drawbacks of the prior art. Accordingly,
the invention on the one hand sets itself the task of producing the bottom opening
on the tubular bag body with a high degree of precision and reliability in a
continuous operation, wherein the structural outlay for the device is to be kept as
15 low as possible. Moreover, the maintenance outlay is to be reduced. Furthermore,
a high production rate is to be enabled.
This problem is solved by a device according to claim 1 and a method according
to claim 20. Preferred embodiments are stated in the dependent claims.
20
According to the invention, the preliminary opening station comprises at least one
guide element with a guide surface inclined towards the transport direction for one
of the bag sections at the open end region of the tubular bag body, wherein the
6
guide surface is connected to a suction element for sucking the bag section against
the guide surface.
During passage through the preliminary opening station, the one bag section at the
open end region of the tubular bag body is conveyed along the guide surface o5 f
the guide element, wherein the one bag section is kept in contact with the guide
surface by means of the suction element. As a result of the inclined arrangement
of the guide surface, the one bag section is moved away from the other bag
section during transport along the preliminary opening station, as a result of which
10 the bag sections at the open end region of the tubular bag body are transferred
from the state lying flat one upon the other at the entrance of the preliminary
opening station into the state spaced apart from one another and partially opening
the bottom opening. This embodiment is characterised by a high degree of
precision and reliability. Furthermore, malfunctions can be prevented or reduced
15 to a minimum. In addition, a high conveying speed can be achieved. By means of
the preliminary opening station, the bottom opening can be opened to an extent
such that the bottom opening, as well described in greater detail below, can be
finalized.
20 In order to enable a direct transfer of the bag body from the preliminary opening
station to the at least one splaying element, it is advantageous if the at least one
guide element of the preliminary opening station is disposed, viewed in the
transport direction, overlapping with the at least one splaying element
7
Accordingly, the wedge element engages between the bag sections of the bag
body as soon as the bag sections have been pulled apart from one another in the
preliminary opening station to essentially the maximum opening width. A
continuous transfer between the preliminary opening station and the formation of
the bottom opening with the splaying element is thus advantageously achieve5 d.
Further opening devices between the preliminary opening station with the inclined
guide surface and the splaying element are preferably not provided.
In order to open the bottom opening during transport of the tubular bag body, it is
10 advantageous if a drive element is provided for driving the guide element with the
guide surface. When the guide element is moved, the bag section is held against
the guide surface by means of the suction element.
In this embodiment, it is advantageous if the guide element comprises a guide
15 belt, in particular an endless belt, connected to the drive element, on which belt
the guide surface is formed for one of the bag sections at the open end region of
the tubular bag body. Accordingly, a suction opening is preferably conveyed
along with the guide belt when the tubular bag body is transported through the
preliminary opening station. In this embodiment, at least one driving roller can be
20 provided as a drive element, at which the guide belt runs off. Two driving rollers
are preferably provided, around which an endless belt with the guide surface for
the tubular bag body is wound.
8
In order to produce the bottom opening uniformly at the open end region of the
tubular bag body, it is advantageous if the preliminary opening station comprises
two guide elements with - in the transport direction - diverging guide surfaces for
the bag sections at the open end region of the tubular bag body. In a preferred
embodiment, an upper guide element is provided with an upper guide surfac5 e
ascending upwards in the transport direction and a lower guide element is
provided with a lower guide surface descending downwards in the transport
direction. In an alternative embodiment, the tubular bag body at the open end
region is angled off at right angles to the transport plane. In this embodiment, the
10 guide elements of the preliminary opening station are disposed horizontal,
wherein the distance between the guide surfaces becomes increasingly greater in
the transport direction.
In order to hold the bag section against the guide surface during transport through
15 the preliminary opening station, it is advantageous if the suction element
comprises at least one suction opening provided on the guide surface for the
purpose of sucking one of the bag sections. The suction opening is connected to a
vacuum generation means, with which the associated bag section is sucked against
the guide surface.
20
According to a particularly preferred embodiment, precisely one suction opening
is disposed on the guide surface. In this embodiment, the bag section is held
against the respective guide surface during transport through the preliminary
9
opening station by means of a single suction opening. Surprisingly, this
embodiment has proved to be more advantageous than the suction belts with the
regular suction hole rows used in the prior art, with which only a comparatively
small opening angle was able to be achieved. The reason for this limitation of the
prior art is to be found in the fact that the successive suction openings woul5 d
cause stresses in the bag body in the event of the bag body being opened beyond
small angles, which stresses could release the bag body from the guide surface.
For this reason, further preliminary opening devices, in particular a compressed
air nozzle and counter-rotating suction box pairs, were provided in the prior art
10 after the suction belts in the transport direction, in order to enable the foldingopen
of the bag bottom. In contrast, the arrangement of a single suction opening
on the guide surface makes it possible for the bag body to be sucked against the
guide surface essentially in a point-like manner. The guide surface can thus have a
comparatively large angle of inclination with respect to the transport plane,
15 without stresses occurring along the main extension of the bag section.
Advantageously, the bag body is thus held reliably against the guide surface. As a
result of the point-like suction of the bag section, the latter can be pulled apart on
the one hand in a linear manner and on the other hand along a curve. Depending
on the application, a vacuum chamber can be suitably constituted adjacent to the
20 guide surface.
Furthermore, provision is preferably made such that the endless belt constituting the
guide element comprises precisely two suction openings. In this embodiment, an
10
endless belt is provided as a guide element, which is provided with precisely two
suction openings. The distance between the two suction openings preferably
corresponds essentially to half the length (i.e. half the girth) of the endless belt.
When the one suction opening is disposed against the guide surface during transport
of the bag body through the preliminary opening station, the other suction openin5 g
is located against the side of the endless belt facing away from the bag body. The
one suction opening is thus active, whilst the other suction opening is inactive. Both
suction openings may be inactive for a short period during circulation of the endless
belt. In particular, this may be the case when both suction openings are located in
10 the region of driving rollers which drive the endless belt.
An embodiment is particularly preferable wherein the preliminary opening station
comprises at least one vacuum generation unit with a vacuum chamber adjacent to
the guide surface of the guide element with the suction opening. The vacuum
15 chamber is preferably disposed in a housing inside the guide element, which
preferably comprises an endless belt. On one side, the vacuum chamber is
connected via a suction line to the vacuum generation means. The endless belt is
passed by on the other side of the vacuum chamber, said endless belt comprising
the suction opening. The associated bag section is thus placed against the guide
20 surface of the endless belt.
According to a particularly preferred embodiment, the opening device comprises
at least one splaying element rotatable about a rotary axis, which splaying element
11
can be introduced during rotation between the bag sections at the open end region
of the tubular bag body, wherein the rotatable splaying element comprises a
wedge element with at least one wedge surface ascending against the direction of
rotation, with which wedge surface the bag sections at the open end region of the
tubular bag body can be splayed apart from one another during its transport on th5 e
transport device, in order to form the bottom opening between the bag sections at
the open end region of the tubular bag body. Depending on the embodiment,
(bottom) openings can be formed at at least one, in particular also at both end
regions of the tubular bag body. For this purpose, the plant can comprise in each
10 case at least one wedge element on both sides in order to form the bottom-side
and top-side opening.
In order to enable the penetration of the splaying element into the open end region
of the tubular bag body, the preliminary opening station is provided in the
15 transport direction before the at least one splaying element, with which
preliminary opening station the bag sections at the open end region of the tubular
bag body can be transferred from a state lying flat one upon the other into a state
spaced apart from one another. In the preliminary opening station, the bottom
opening is opened to an extent such that the narrow end of the wedge element can
20 enter between the bag sections at the open end region of the tubular bag body.
In this embodiment, a wedge-shaped splaying element is preferably used to
produce the bottom opening after the preliminary opening station, the wedge
12
surface of said splaying element ascending against the direction of rotation, i.e.
from a front end region to a rear end region, for the bag body on the transport
device. During transport of the tubular bag body through the opening device, the
rotating wedge element is introduced between the bag sections lying one upon the
other at the open end region of the tubular bag body, wherein the bag sections ar5 e
pushed apart by the wedge surface of the wedge element ascending to the rear. By
means of the wedge element, the opening width of the bottom opening of the
tubular bag body is continuously enlarged. Advantageously, therefore, the bottom
opening at the open end region of the tubular bag body can be formed particularly
10 reliably. The service life of the opening device can thus be increased considerably.
The wedge element preferably comprises an essentially vertical rotary axis, i.e.
running normal to the support surface for the bag body on the transport device,
when the bag sections at the open end region of the tubular bag body are
conveyed in a horizontal position through the opening device. In this embodiment,
15 the ascending wedge surface is disposed at an angle to the horizontal transport
plane, wherein the wedge surface, depending on the embodiment, extends from
the front end to the rear end obliquely upwards or obliquely downwards.
Alternatively, the bag sections at the open end region of the bag-shaped tubular
body can be bent off, for example, through 90° from the supporting surface on the
20 transport device. In this embodiment, the wedge element can be disposed rotating
about a horizontal rotary axis. In this case, the wedge surface of the wedge
element is disposed ascending in a horizontal plane against the direction of
rotation. The rotary motion of the wedge element is adapted to the transport speed
13
along the transport device in such a way that the bottom opening is formed at the
open end region of the tubular bag body. The embodiment according to the
invention is characterised by a low structural outlay, wherein a mechanism for
extending a multi-part splaying tool can be dispensed with. Moreover, the rotary
mounting of the splaying tool is particularly simple. Furthermore, it i5 s
advantageous that the wedge-shaped splaying element operates reliably in a
continuous operation with a high production rate. Advantageously, the
maintenance outlay can be kept low.
10 In order to splay the bag sections at the open end region of the bag body away
from one another in opposite directions, it is advantageous if the wedge element
comprises two wedge surfaces diverging from one another in the transport
direction, preferably an upper wedge surface and a lower wedge surface, wherein
the upper wedge surface and the lower wedge surface are preferably each
15 disposed at an acute angle to the supporting surface for the tubular bag body on
the transport device. In the opening device, therefore, the upper bag section of the
tubular bag body is preferably pushed upwards by means of the upper wedge
surface of the wedge element, wherein the lower bag section is pushed
downwards by means of the lower wedge surface of the wedge element. The
20 bottom opening can thus be formed particularly reliably on the tubular bag body.
The upper wedge surface and the lower wedge surface are preferably disposed
symmetrical with respect to the supporting surface for the tubular bag body on the
transport device. The bag sections of the tubular bag body can thus be pushed
14
apart uniformly around the central plane formed by the supporting surface on the
transport device, in order to form the bottom opening at the open end region of the
tubular bag body.
In order to form the bottom opening at the open end region of the tubular bag bod5 y
with the required opening width, it is advantageous if the opening device comprises
at least two splaying elements following one another in the transport direction of the
tubular bag body. The preceding wedge element, viewed in the transport direction
of the tubular bag body, is preferably provided for producing a first, narrower
10 opening width of the bottom opening and the following wedge element, viewed in
the transport direction, is provided for producing a second, wider opening width of
the bottom opening at the open end region of the tubular bag body.
For this purpose, it is advantageous if the wedge elements of successive splaying
15 elements have different wedge heights increasing in the transport direction of the
tubular bag body, preferably normal to the supporting surface for the tubular bag
body on the transport device. Accordingly, the wedge height of the wedge element,
i.e. the maximum extension of the wedge element normal to the supporting surface
for the bag body on the transport device, increases from wedge element to wedge
20 element as viewed in the transport direction. Advantageously, the bottom opening is
thus formed in steps using structurally straightforward means.
15
In order to enable a continuous formation of the bottom opening on the tubular
bag body, it is advantageous if the splaying elements comprise wedge elements
which overlap during rotation in the transport direction of the tubular bag body,
wherein a - in the transport direction - preceding wedge element comprises a
cutout for the passage of a - in the transport direction - following wedge element5 .
In this embodiment, the wedge elements are disposed temporarily overlapping
during the rotary motion, wherein the front end region of the - in the transport
direction - following wedge element passes through the cutout of the - in the
transport direction - preceding wedge element. Advantageously, therefore, the - in
10 the transport direction - following wedge element can already pass between the
bag sections of the tubular bag body before the - in the transport direction -
preceding wedge element has exited from the tubular bag body. In this
embodiment, malfunctions, in particular a pile-up of bag bodies in the opening
device, are advantageously avoided in a reliable manner.
15
For the opening of the bottom region of conventional bag bodies, it has proved to
be particularly advantageous if precisely three splaying elements are provided,
which comprise wedge elements overlapping during rotation in the transport
direction for introduction between the bag sections at the open end region of the
20 tubular bag body. This embodiment enables a continuous formation of the bottom
opening, wherein malfunctions are for the most part prevented.
16
According to a particularly preferred embodiment, a wedge element comprises, at
a rear end region as related to the direction of rotation, a holding section for
holding a rear region of the tubular bag body, as related to the transport direction,
during the introduction of the wedge surface of the - in the transport direction -
following wedge element into a front region of the tubular bag body. The tubula5 r
bag body can advantageously thus be kept in a partially opened state by means of
one wedge element, while the - in the transport direction - following wedge
element passes into the open end region of the tubular bag body in order to widen
the bottom opening.
10
In this embodiment, it is advantageous if the holding section of the wedge element
comprises a guiding edge, which is disposed essentially at the same height as the rear
end of the wedge surface, as viewed in the direction of rotation. The height relates
here to the distance of the guiding edge from the supporting surface for the tubular
15 bag body on the transport device. The open end region on the tubular bag body is kept
in a partially opened state by means of the guiding edge of the wedge element when
the following wedge element enters into the bottom region of the tubular bag body, in
order to gradually increase the opening width of the bottom opening.
20 In order to enable, on the one hand, an overlapping arrangement of successive
splaying elements and, on the other hand, holding of the tubular bag body in the
current, partially opened state, it is advantageous if the wedge element comprises
the cutout for the passage of the - in the transport direction - following wedge
17
element between the wedge surface and the holding section. Accordingly, the
wedge element comprises the wedge surface at the front end (viewed in the
direction of rotation) and the holding section at the rear end, wherein the cutout is
provided between the wedge surface and the holding section to allow clearance for
the rotary motion of the following wedge element. The wedge elements are als5 o
disposed partially overlapping by means of cutouts in order to prevent the already
partially opened end region of the tubular bag body being able to close again.
In order to facilitate the introduction of the wedge element into the open end
10 region of the tubular bag body, it is advantageous if the wedge element is curved
in the form of an arc, in particular in the form of an arc of circle, in the direction
of rotation. Accordingly, the wedge elements are constituted arc-shaped in
relation to the supporting surface for the tubular bag body on the transport device.
The bottom opening can thus be formed particularly reliably.
15
In order to set the splaying element into a rotary motion, it is advantageous if the
wedge element is connected to a shaft element, which is coupled to a drive and the
rotary axis of the shaft element is preferably disposed essentially normal to the
supporting surface for the bag body on the transport device. Accordingly, the
20 wedge element preferably comprises an essentially vertical rotary axis, i.e.
disposed normal to the supporting surface in the transport device.
18
With regard to a structurally straightforward, stable embodiment, it is
advantageous if the wedge element comprises at least one plate part, which is
preferably disposed essentially normal to the supporting surface for the bag body
on the transport device and which forms a wedge surface at an end face.
Accordingly, the wedge surfaces are preferably formed at the upper and lowe5 r
edge of a plate part standing essentially vertical on the supporting surface in the
transport device.
For production-related reasons, provision is preferably made such that the wedge
10 element comprises at least one disc part which is preferably disposed essentially
parallel to the supporting surface for the bag body on the transport device and which
is connected at the outer edge region to the plate part comprising the wedge surface.
The problem underlying the invention is also solved by a method of the type
15 mentioned at the outset, wherein at least one of the bag sections in the preliminary
opening station is transported along a guide surface inclined towards the transport
direction, wherein the bag section is sucked against the guide surface.
The invention is explained in greater detail below with the aid of a preferred example
20 of embodiment, to which however it is not intended to be limited. In the drawing:
19
Fig. 1a shows schematically a diagrammatic view of a plant for the production of
bags, wherein an opening device according to the invention is provided for
opening the end region of a bag body;
Fig. 1b shows schematically a part of a preliminary opening station of the plan5 t
according to fig. 1a; and
Fig. 2 to 7 show schematically views of a part of the opening device according to
fig. 1a during the formation of the bag opening by means of wedge-shaped
10 splaying elements, which splay apart the bag sections lying one upon the other at
the open end region of the tubular bag body.
Fig. 1a shows a part of a plant 1 for producing bags, wherein a material web, in
particular made of a woven material, is processed in various stations to form
15 finished cross-bottom bags or cross-bottom valve bags. Plant 1 comprises a
separating device (not shown) for the purpose of separating the material web into
tubular bag bodies 2. Tubular bag bodies 2 comprise two bag sections 2', 2'' lying
one upon the other, wherein each bag section 2', 2'' can be constituted by a
plurality of layers of different material. Tubular bag bodies 2 are transferred to a
20 transport device 3. In transport device 3, bag bodies 2 are successively conveyed
on an essentially horizontal supporting surface 4 of transport device 3 in a flatlying
state in transport direction 5 transverse to their longitudinal extension axis 6
shown diagrammatically in fig. 2.
20
As can further be seen from fig. 1a, see also fig. 2 to 6, transport device 3 is
connected to an opening device 7 for forming a bottom opening 8 between bag
sections 2', 2'' at open end region 9 of tubular bag body 2. Opening device 7
comprises a preliminary opening station 23, by means of which bag sections 2', 2''
at open end region 8 of tubular bag body 9 can be transferred from a state lyin5 g
flat one upon the other into a state spaced apart from one another.
As can be seen from fig. 1a, preliminary opening station 23 comprises an upper
guide element 24 with an upper guide surface 24' ascending upwards in transport
10 direction 5 and a lower guide element 25 with a lower guide surface 25'
descending downwards in transport direction 5. Endless belts are provided as
guide elements 24, 25 in the embodiment shown, said endless belts being driven
by driving rollers 24'', 24'''. Guide elements 24, 25 are each connected to a suction
element 26 for sucking associated bag section 2', 2''. Suction elements 26 each
15 comprise at least one suction opening 26' on guide surface 24', 25' of the endless
belt. In the embodiment shown, each endless belt comprises precisely two suction
openings 26' (see fig. 1b).
As can be seen from fig. 1b, preliminary opening station 23 comprises a vacuum
20 generation unit 27 for each guide element 24, 25. Vacuum generation units 27
each comprise a vacuum chamber 27', which extends adjacent to guide surface
24', 25' of upper 24 and lower guide element 25. Vacuum chamber 27' is provided
in a housing 27'', which is disposed inside guide element 24, 25. In order to
21
produce a vacuum at suction opening 26' of guide element 24, 25, vacuum
chamber 27' is connected via a suction line 27''' to vacuum generation means (not
shown), for example a vacuum pump. When tubular bag body 2 is conveyed
through preliminary opening station 23, bag sections 2', 2'' are placed against
guide surfaces 24', 25' of guide elements 24, 25, said guide surfaces divergi5 ng
from one another in transport direction 5. Bag sections 2', 2'' are thus continuously
transferred from the state lying flat one upon the other at the entrance of
preliminary opening station 23 into the state spaced apart from one another and
partially opening bottom opening 8.
10
As can further be seen from fig. 1a, opening device 7 comprises a plurality of
splaying elements 10 following preliminary opening station 23 in transport
direction 5, said splaying elements each being mounted rotatably about a vertical
rotary axis 11. Bottom opening 8 of tubular bag body 2 is opened by preliminary
15 opening station 23 sufficiently for splaying elements 10 to be able to penetrate
between bag sections 2', 2'' at open end region 9 of tubular bag body 2. During the
rotary motion, splaying elements 10 pass between bag sections 2', 2'' at open end
region 9 of tubular bag body 2, thereby forming the bottom opening 8.
20 As can further be seen from fig. 1a, a bottom folding station 28 follows opening
device 7 in transport direction 5, in which bottom folding station the geometry of
the opening is brought into a correct, rectangular position with the aid of finger
22
elements 29. Tubular bag bodies 2 can then be processed in a manner known per
se to form the finished bags.
Fig. 2 to 7 show splaying elements 10 at different stages in the formation of bag
opening 8. Tubular bag bodies 2 can be conveyed through opening device 7 in a
state lying flat one upon the other in a horizontal plane, as is shown in fig. 3 to 75 .
Alternatively, the bottom region can be angled off during transport through
opening device 7 (see schematically fig. 2).
According to fig. 2, 3, tubular bag body 2 is transported straightly with partially
10 opened bottom opening 8 from preliminary opening station 23 to splaying
elements 10. According to fig. 3 to 6, the opening width of bottom opening 8 is
gradually increased, so that bottom opening 8 is completely opened after splaying
elements 10.
15 As can be seen from fig. 2 to 7, rotatably mounted splaying elements 10 each
comprise a wedge element 12, on which wedge surfaces 14 are formed, said
wedge surfaces ascending against direction of rotation 13, i.e. from the front end
region to the rear end region. During transport of tubular bag bodies 2 on transport
device 3, wedge elements 12 with wedge surfaces 14 increasingly push apart
20 mutually opposite bag sections 2', 2'' at open end region 9 of tubular bag body 2,
as a result of which bottom opening 8 is produced between bag sections 2', 2'' at
open end region 9 of tubular bag body 2. Each wedge element 12 comprises an
upper wedge surface 14' for an upper bag section 2' and a lower wedge surface 14''
23
for a lower bag section 2''. Wedge surfaces 14', 14'' of wedge elements 12 are each
disposed at an acute angle to horizontal supporting surface 4 for tubular bag body
2 on transport device 3.
As can further be seen from fig. 2 to 7, wedge element 12 is connected to a shaf5 t
element 15, which is disposed essentially vertical, i.e. normal to supporting
surface 4 for bag body 2 on transport device 3, and which is set into a rotary
motion by a drive (not shown). In the embodiment shown, wedge surfaces 14 are
formed on essentially vertically standing plate elements 16. Front wedge element
10 12', viewed in transport direction 5, comprises a single plate element 16. Middle
wedge element 12'', viewed in transport direction 5, and rear wedge element 12''',
viewed in transport direction 5, each comprise an upper plate part 16', which
comprises upper wedge surface 14' at an upper end face, and a lower plate part
16'', which comprises lower wedge surface 14'' at a lower end face. Plate elements
15 16; 16', 16'' are curved in plan view in the form of an arc of circle corresponding
to direction of rotation 13. Moreover, wedge elements 12 comprise disc parts 17,
which extend essentially on a horizontal plane and which, on the one hand, are
coupled to shaft element 15 and, on the other hand, at the outer edge regions
support plate parts 16 with wedge surfaces 14; 14', 14''.
20
As can further be seen from fig. 2 to 7, opening device 7 comprises, in the
embodiment shown, three splaying elements 10 following one another in transport
direction 5 of tubular bag body 2. Individual splaying elements 10 comprise
24
wedge elements 12, which have different wedge heights h increasing in transport
direction 5 of tubular bag body 2. Wedge height h is measured here by the
distance between the rear end of wedge surface 14, viewed in direction of rotation
11, and supporting surface 4 for tubular bag body 2 on transport device 3.
Opening width b of bottom opening 8 (see fig. 6) is enlarged from wedge elemen5 t
12 to wedge element 12.
As can further be seen from fig. 2 to 7, wedge elements 12 are disposed partially
overlapping by means of cutouts 18 during rotation viewed in transport direction
10 5, in order to achieve a continuous increase in opening width b of bottom opening
8. For this purpose, front wedge element 12', viewed in transport direction 5,
comprises a cutout 18' for the passage of middle wedge element 12'' following in
transport direction 5. Correspondingly, middle wedge element 12'' comprises a
cutout 18'' to allow clearance for the rotary motion of rear wedge element 12''',
15 viewed in transport direction 5.
As can further be seen from fig. 2 to 7, wedge element 12 comprises holding
sections 19 at a rear end region, as related to direction of rotation 13, by means of
which holding sections rear sections 20 of bag sections 2', 2'', as related to
20 transport direction 5, are held in the current opening position, while wedge surface
14 of wedge element 12 following in transport direction 5 is introduced into front
regions 21 of bag sections 2', 2'' of same bag body 2. For this purpose, holding
sections 19 of wedge element 12 comprise at least one guiding edge 22, in the
25
shown embodiment an upper guiding edge 22' and a lower guiding edge 22'',
which are disposed essentially at the same height as the rear end, viewed in
direction of rotation 13, of associated wedge surfaces 14', 14'' of respective wedge
element 12.
5
In the embodiment shown, front wedge element 12', viewed in transport direction
5, on the one hand comprises holding sections 19', which are assigned to upper
bag section 2' and lower bag section 2'' of tubular bag body 2. The transfer of
tubular bag body 2 from front wedge element 12' to middle wedge element 12''
10 can thus take place reliably. On the other hand, middle wedge element 12'',
viewed in transport direction 5, comprises corresponding holding sections 19'', in
order to bring about a reliable transfer of bag body 2 to rear wedge element 12''',
viewed in transport direction 5.
15 The terms "lower" and "upper" for the arrangement of various components, such
as the wedge elements, are used in the present disclosure by way of example for a
preferred operational position, in which bag sections 2', 2'' at open end region 9 of
tubular bag body 2 are transported in a horizontal position. However, an
embodiment can of course be provided, wherein bag sections 2', 2'' are for
20 example bent off through 90° from the transport plane. In this embodiment, the
components of the plant, such as wedge elements 12, are then disposed tilted by a
corresponding angle.
26
We Claim
1. A device for forming a bottom opening (8) between bag sections (2', 2'') at
the open end region (9) of a tubular bag body (2), with a transport device
(3) for transporting the bag body (2) in a transport direction (5) transverse
to its longitudinal extension (6), and with an opening device (7) fo5 r
forming the bottom opening (8) between the bag sections (2', 2'') at the
open end region (9) of the tubular bag body (2), wherein the opening
device (7) comprises a preliminary opening station (23), with which the
bag sections (2', 2'') at the open end region (9) of the tubular bag body (2)
10 can be transferred from a state lying flat one upon the other into a state
spaced apart from one another, wherein the opening device (7) comprises
at least one splaying element (10) rotatable about a rotary axis (11), which
splaying element can be introduced during rotation between the bag
sections (2', 2'') at the open end region (9) of the tubular bag body (2),
15 wherein the rotatable splaying element (10) comprises a wedge element
(12; 12', 12'', 12''') with at least one wedge surface (14; 14', 14'') ascending
against the direction of rotation (13), with which wedge surface the bag
sections (2', 2'') at the open end region (9) of the tubular bag body (2) can
be splayed apart during its transport on the transport device (3), in order to
20 form the bottom opening (8) between the bag sections (2', 2'') at the open
end region (9) of the tubular bag body (2), characterised in that the
preliminary opening station (23) comprises at least one guide element (24,
25) with a guide surface (24', 25') inclined towards the transport direction
27
(5) for one of the bag sections (2', 2'') at the open end region (9) of the
tubular bag body (2), wherein the guide surface (24', 25') is connected to a
suction element (26) for sucking the bag section (2', 2'') against the guide
surface (24', 25'),
wherein the at least one guide element (24, 25) of the preliminary openi5 ng
station (23) is disposed, viewed in the transport direction (5), overlapping
with the at least one splaying element (10).
2. The device according to claim 1, characterised in that a drive element (24'',
24''') is provided for driving the guide element (24, 25) with the guide
10 surface (24', 25'),
wherein preferably the guide element (24, 25) comprises a guide belt, in
particular an endless belt, connected to the drive element (24'', 24'''), on
which belt the guide surface (24', 25') is formed for one of the bag sections
(2', 2'') at the open end region (9) of the tubular bag body (2).
15 3. .The device according to claim 1 or 2, characterised in that the preliminary
opening station (23) comprises two guide elements (24, 25) with - in the
transport direction (5) - diverging guide surfaces (24', 25') for the bag
sections (2', 2'') at the open end region (9) of the tubular bag body (2).
4. The device according to any one of claims 1 to 3, characterised in that the
20 suction element (26) comprises at least one suction opening (26') provided
on the guide surface (24', 25') for the purpose of sucking one of the bag
sections (2', 2''),
28
wherein preferably precisely one suction opening (26’) is disposed on the
guide surface (24', 25'),
wherein the endless belt constituting the guide element (24, 25) comprises
preferably precisely two suction openings (26’).
5. The device according to claim 4, characterised in that the preliminar5 y
opening station (23) comprises at least one vacuum generation unit (27)
with a vacuum chamber (27') adjacent to the guide surface (24', 25') of the
guide element (24, 25) with the suction opening (26).
6. The device according to any one of claims 1 to 9, characterised in that the
10 wedge element (12) comprises two wedge surfaces diverging from one
another in the transport direction (5), preferably an upper wedge surface
(14’) and a lower wedge surface (14''), wherein the upper wedge surface
(14’) and the lower wedge surface (14'') are preferably each disposed at an
acute angle to the supporting surface (4) for the tubular bag body (2) on
15 the transport device (3).
7. The device according to any one of claims 1 to 6, characterised in that the
opening device (7) comprises at least two splaying elements (10) following
one another in the transport direction (5) of the tubular bag body (2),
wherein the wedge elements (12; 12', 12'', 12''') of successive splaying
20 elements (10) preferably have different wedge heights (h) increasing in the
transport direction (5) of the tubular bag body (2), preferably normal to the
supporting surface (4) for the tubular bag body (2) on the transport device
(3).
29
8. The device according to claim 7, characterised in that the splaying
elements (10) comprise wedge elements (12; 12', 12'', 12''') overlapping
during rotation in the transport direction (5) of the tubular bag body (2),
wherein a - in the transport direction - preceding wedge element (12; 12',
12'') comprises a cutout (18) for the passage of a - in the transport directio5 n
(5) - following wedge element (12; 12'', 12'''),
wherein preferably precisely three splaying elements (10) are provided,
which comprise wedge elements (12; 12', 12'', 12''') overlapping during
rotation in the transport direction (5) for introduction between the bag
10 sections (2', 2'') at the open end region (9) of the tubular bag body (2).
9. The device according to any one of claims 1 to 8, characterised in that a
wedge element (12; 12', 12'', 12''') comprises, at a rear end region as
related to the direction of rotation (13), a holding section (19; 19', 19'') for
holding a rear region (20) of the tubular bag body (2), as related to the
15 transport direction (5), during the introduction of the wedge surface (14) of
the - in the transport direction (5) - following wedge element (12; 12'',
12''') into a front region (21) of the tubular bag body (2), wherein the
holding section (19; 19', 19'') of the wedge element (12; 12', 12'', 12''')
preferably comprises a guiding edge (22), which is disposed essentially at
20 the same height as the rear end of the wedge surface (14; 14', 14''), as
viewed in the direction of rotation (13),
wherein preferably the wedge element (12; 12', 12'', 12''') comprises the
cutout (18) for the passage of the - in the transport direction (5) - following
30
wedge element (12; 12'', 12''') between the wedge surface (14; 14', 14'') and
the holding section (19; 19', 19'').
10. The device according to any one of claims 1 to 9, characterised in that the
wedge element (12; 12', 12'', 12''') is curved in the form of an arc, in
particular in the form of an arc of circle, in the direction of rotation (5 13).
11. The device according to any one of claims 1 to 10, characterised in that the
wedge element (12; 12', 12'', 12''') is connected to a shaft element (15),
which is coupled to a drive and the rotary axis (11) of the shaft element is
preferably disposed essentially normal to the supporting surface (4) for the
10 bag body (2) on the transport device (3).
12. The device according to any one of claims 1 to 11, characterised in that the
wedge element (12; 12', 12'', 12''') comprises at least one plate part (16;
16', 16''), which is preferably disposed essentially normal to the supporting
surface (4) for the bag body (2) on the transport device (3) and which
15 forms a wedge surface (14; 14', 14'') at an end face,
wherein preferably the wedge element (12; 12', 12'', 12''') comprises at
least one disc part (17) which is preferably disposed essentially parallel to
the supporting surface (4) for the bag body (2) on the transport device (3)
and which is connected at the outer edge region to the plate part (16)
20 comprising the wedge surface (14, 14', 14'').
13. A method for forming a bottom opening (8) between bag sections (2', 2'')
at the open end region (9) of a tubular bag body (2), wherein the bag body
(2) is transported in a transport direction (5) transverse to its longitudinal
31
extension (2a) and, during transport, a bottom opening (8) between the bag
sections (2’, 2'') at the open end region (9) of the tubular bag body (2) is
formed, wherein the bag sections (2’, 2'') at the open end region (9) of the
tubular bag body (2) are transferred in a preliminary opening station (23)
from a state lying flat one upon the other into a state spaced apart from on5 e
another, before a splaying element (10) rotating about a rotary axis (11) is
introduced between the bag sections (2', 2'') at the open end region (9) of
the tubular bag body (2), in order to form the bottom opening (8) between
the bag sections (2', 2'') at the open end region (9) of the tubular bag body
10 (2), characterised in that at least one of the bag sections (2’, 2'') in the
preliminary opening station (23) is transported along a guide surface (24’,
25’) at least one guide surface (24, 25) inclined towards the transport
direction (5), wherein the bag section (2', 2'') is sucked against the guide
surface (24’, 25’), wherein at least one guide surface (24, 25) of the
15 opening station (23) seen in transport direction (5) is arranged overlapping
with at least one splaying element.
14. The method according to claim 13, characterised in that the bag body (2) is
sucked against the guide surface (24’, 25’) at precisely one suction
opening (26’) during transport through the preliminary opening station
20 (23).
15. The method according to claim 13 or 14, characterised in that the guide
surface (24', 25') for the bag body (2) on an endless belt is constituted with
precisely two suction openings (26’), wherein at most one of the suction
32
openings (26’) is disposed on the guide surface (24', 25') during the
circulation of the endless belt.