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 the opening device comprises at least one splaying eleme5 nt
rotatable 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.
Furthermore, the invention relates to a method for forming a bottom opening between bag
10 sections at the open end region of a tubular bag body, wherein the bag body is transported
in a transport direction transverse to its longitudinal extension and, during transport, a
splaying element rotating about a rotary axis is introduced between the bag sections at the
open end region of the tubular bag body.
15 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 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
20 open end of the tubular bag body. Various 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
25 of a separating finger. As the tube moves onwards, a single splaying disc passes between
3
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.
5
The known embodiment, however, has the drawback that the splaying of the tube end
takes place over a comparatively small distance over steep wedge surfaces. Malfunctions
can thus occur.
10 Furthermore, 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 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,
15 which comprises rows of suction holes, is provided for opening the tube bottom. The
suction boxes are connected 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
20 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.
4
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 articulated joints at its ends and 5 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.
10 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.
15 Moreover, bottom opening stations with rotating splaying tools with an upper part and a
lower part have been used in the prior art, which are moved apart from one another by
means of a mechanism during the rotary motion. Such multi-part splaying tools, however,
have the disadvantage of being expensive in terms of design and susceptible to defects.
Moreover, extensive adjustments to such splaying tools may be required.
20
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 device
25 for forming a bottom opening, such as mentioned at the outset, which mitigates or
5
eliminates the drawbacks of the prior art. Accordingly, the invention on the one hand sets
itself the task of producing the bottom openings with a high degree of precision and
reliability in a continuous operation, wherein the structural outlay for the device is to be
kept as low as possible. Moreover, the maintenance outlay is to be reduced. Furthermore,
a high production rate is to be enabled5 .
The problem is solved by a device according to claim 1 and a method according to claim
19. Preferred embodiments are stated in the dependent claims.
10 According to the invention, 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 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.
15
According to the invention, therefore, a wedge-shaped splaying element is used to open
the bag bottom, the wedge 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,
20 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 are 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
25 region of the tubular bag body can be formed particularly reliably. The service life of the
6
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, the ascending wedge surface is disposed at an angle to the horizonta5 l
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 transport device. In this
10 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 along the transport device in such a way that the bottom opening is
formed at the open end region of the tubular body. Depending on the embodiment,
15 (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 case at least one
wedge element on both sides in order to form the bottom-side and top-side opening. 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.
20 Moreover, the rotary mounting of the splaying tool is particularly simple. Furthermore, it
is 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.
7
In order to form the bottom opening at the open end region of the tubular bag body with
the required opening width, 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 opening width of the bottom opening and th5 e
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.
10 For this purpose, the wedge elements of successive splaying 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,
15 increases from wedge element to wedge element as viewed in the transport direction.
Advantageously, the bottom opening is thus formed in steps using structurally
straightforward means.
According to a particularly preferred embodiment, at least one splaying element,
20 preferably each splaying element, comprises an adjustment device for adjusting the
wedge height of the splaying element. In this embodiment, the wedge height is adjustable.
An application specific adjustment can thus advantageously be made. The adjustment
device can comprise, for example, a longitudinal guide extending in the height direction
for the adjustment of two sections or parts of the splaying element with respect to one
8
another. Furthermore, arresting means can be provided for arresting the sections or parts
of the splaying element in the adjusted relative position with respect to one another.
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 tw5 o
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 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
10 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 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
15 surface for the tubular bag body on the transport device. The bag sections of the tubular
bag body can thus be pushed 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.
20 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 element. In this embodiment, the wedge
25 elements are disposed temporarily overlapping during the rotary motion, wherein the
9
front edge 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 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 thi5 s
embodiment, malfunctions, in particular a pile-up of bag bodies in the opening device, are
advantageously avoided in a reliable manner.
For the opening of the bottom region of conventional bag bodies, it has proved to be
10 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 tubular bag body.
This embodiment enables a continuous formation of the bottom opening, wherein
malfunctions are for the most part prevented.
15
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
20 element into a front region of the tubular bag body. The tubular 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 leading 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 bag body on the
transport device. The open end region on the tubular bag body is kept in a partiall5 y
opened state by means of the leading 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.
10 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 element between the wedge surface
and the holding section. Accordingly, the wedge element comprises the wedge surface at
15 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 also 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.
20
In order to facilitate the introduction of the wedge element into the open end 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
11
tubular bag body on the transport device. The bottom opening can thus be formed
particularly reliably.
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 5 of
the shaft element is preferably disposed essentially normal to the supporting surface for
the bag body on the transport device. Accordingly, the wedge element preferably
comprises an essentially vertical rotary axis, i.e. disposed normal to the supporting
surface in the transport device.
10
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
15 formed at the upper and lower 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 element
comprises at least one disc part which is preferably disposed essentially parallel to the
20 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.
In order to enable the penetration of the splaying element into the
open end region of the tubular bag body, it is advantageous if the opening device
25 comprises a preliminary opening station in the transport direction, with which the bag
12
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 enter between the bag sections at the open end region of the tubular
bag body5 .
According to a preferred embodiment, 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 guide surface
10 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 of 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
15 one bag section is moved away from the other bag section during transport along the
preliminary opening station, as a result of which 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.
20
In order to enable a direct transfer of the bag body from the preliminary opening station
to the at least once 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. Accordingly, the wedge element
25 engages between the bag sections of the bag body as soon as the bag sections have been
13
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
achieved. Further opening devices between the preliminary opening station with the
inclined guide surface and the splaying element are preferably not provided5 .
In order to open the bottom opening during transport of the tubular bag body, it is
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
10 surface by means of the suction element.
In this embodiment, it is advantageous if the guide element comprises a guide 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.
15 Accordingly, the suction opening is 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 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.
20
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
25 element is provided with an upper guide surface ascending upwards in the transport
14
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 guide elements of the preliminary opening station are disposed
horizontal, wherein the distance between the guide surfaces becomes increasingly greate5 r
in the transport direction.
In order to hold the bag section against the guide surface during transport through the
preliminary opening station, it is advantageous if the suction element comprises at least
10 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.
According to a particularly preferred embodiment, precisely one suction opening is
15 disposed on the guide surface. In this embodiment, the bag section is held against the
respective guide surface during transport through the preliminary 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
20 reason for this limitation of the prior art is to be found in the fact that the successive
suction openings would 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 after the
25 suction belts in the transport direction, in order to enable the folding-open of the bag
15
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, without stresses occurring along the main
extension of the bag section. Advantageously, the bag body is thus held reliably agains5 t
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 guide surface.
10
Furthermore, provision is preferably made such that the endless belt constituting the
guide element comprises precisely two suction openings. In this embodiment, an 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
15 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 opening 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
20 short period during circulation of the endless belt. In particular, this may be the case when
both suction openings are located in the region of the driving rollers which drive the
endless belt.
An embodiment is particularly preferable wherein the preliminary opening station
25 comprises at least one vacuum generation unit with a vacuum chamber adjacent to the
16
guide surface of the guide element with the suction opening. The vacuum 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 i5 s
thus placed against the guide surface of the endless belt.
The problem underlying the invention is also solved by a method of the type mentioned at
the outset, wherein the rotatable splaying element comprises a wedge element with at
10 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 are splayed apart
from one another 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.
15 The invention is explained in greater detail below with the aid of a preferred example of
embodiment, to which however it is not intended to be limited. In the drawing:
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
20 region of a bag body;
Fig. 1b shows schematically a part of a preliminary opening station of the plant 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 splaying elements,
17
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 finished cross-botto5 m
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
10 are transferred to a 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.
15 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 lying flat one upon the other into a state spaced apart
20 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 direction 5
and a lower guide element 25 with a lower guide surface 25' descending downwards in
25 transport direction 5. Endless belts are provided as guide elements 24, 25 in the
18
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 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)5 .
As can be seen from fig. 1b, preliminary opening station 23 comprises a vacuum
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
10 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 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',
15 2'' are placed against guide surfaces 24', 25' of guide elements 24, 25, said guide surfaces
diverging 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.
20
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 opening station 23 sufficiently
25 for splaying elements 10 to be able to penetrate between bag sections 2', 2'' at open end
19
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.
As can further be seen from fig. 1a, a bottom folding station 28 follows opening device 5 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 elements 29. Tubular
bag bodies 2 can then be processed in a manner known per se to form the finished bags.
10 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 7. Alternatively, the
bottom region can be angled off during transport through opening device 7 (see
schematically fig. 2).
15
According to fig. 2, 3, tubular bag body 2 is transported straightly with partially opened
bottom opening 8 from preliminary opening station 23 to splaying elements 10.
According to fig. 3 to 7, the opening width of bottom opening 8 is gradually increased, so
that bottom opening 8 is completely opened after splaying elements 10.
20
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
25 with wedge surfaces 14 increasingly push apart mutually opposite bag sections 2', 2'' at
20
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'' 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 fo5 r
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 shaft element
15, which is disposed essentially vertical, i.e. normal to supporting surface 4 for bag body
10 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 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
15 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
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
20 element 15 and, on the other hand, at the outer edge regions support plate parts 16 with
wedge surfaces 14; 14', 14''.
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
25 tubular bag body 2. Individual splaying elements 10 comprise wedge elements 12, which
21
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 element 12 to wedge element 5 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 5, in
order to achieve a continuous increase in opening width b of bottom opening 8. For this
10 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''', viewed in transport direction 5.
15 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 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
20 body 2. For this purpose, holding sections 19 of wedge element 12 comprise at least one
leading edge 22, in the shown embodiment an upper leading edge 22' and a lower leading
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.
22
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'' can thus take place reliably. On the
other hand, middle wedge element 12'', viewed in transport direction 5, comprise5 s
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.
The terms "lower" and "upper" for the arrangement of various components, such as the
10 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 example bent off through 90° from the
transport plane. In this embodiment, the components of the plant, such as wedge elements
15 12, are then disposed tilted by a corresponding angle.
23
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) for forming th5 e
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 at
least one splaying element (10) rotatable about a rotary axis (11), which
splaying element can be introduced during rotation between the bag sections
10 (2', 2'') at the open end region (9) of the tubular bag body (2), 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 each rotatable splaying element (10) comprises a wedge element
(12; 12', 12'', 12''') with at least one wedge surface (14; 14', 14'') ascending
15 against the direction of rotation (13), with which 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 form the bottom
opening (8) between the bag sections (2', 2'') at the open end region (9) of the
tubular bag body (2), and that the wedge elements (12; 12', 12'', 12''') of
20 successive splaying elements (10) have different wedge heights (h) increasing
in the transport direction (5) of the tubular bag body (2).
2. The device according to claim 1, characterised in that the wedge element (12)
comprises two wedge surfaces diverging from one another in the transport
24
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 the transport device (3).
3. The device according to claim 1 or 2, characterised in that the splayi5 ng
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 direction (5) -
10 following wedge element (12; 12'', 12''').
4. The device according to claim 3, characterised in that 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 sections (2', 2'') at the open end region (9) of the tubular bag
15 body (2).
5. The device according to any one of claims 1 to 4, 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 transport
20 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).
25
6. The device according to claim 5, characterised in that the holding section (19;
19', 19'') of the wedge element (12; 12', 12'', 12''') comprises a leading edge
(22), which is disposed essentially at the same height as the rear end of the
wedge surface (14; 14', 14''), as viewed in the direction of rotation (13).
7. The device according to claim 5 or 6, characterised in that the wedge elemen5 t
(12; 12', 12'', 12''') comprises the cutout (18) for the passage of the - in the
transport direction (5) - following wedge element (12; 12'', 12''') between the
wedge surface (14; 14', 14'') and the holding section (19; 19', 19'').
8. The device according to any one of claims 1 to 7, characterised in that the
10 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 (13).
9. The device according to any one of claims 1 to 8, 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
15 disposed essentially normal to the supporting surface (4) for the bag body (2)
on the transport device (3).
10. The device according to any one of claims 1 to 9, 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
20 surface (4) for the bag body (2) on the transport device (3) and which forms a
wedge surface (14; 14', 14'') at an end facewherein 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
26
bag body (2) on the transport device (3) and which is connected at the outer
edge region to the plate part (16) comprising the wedge surface (14, 14', 14'').
11. The device according to any one of claims 1 to 10, characterised in that 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 (5 2)
can be transferred from a state lying flat one upon the other into a state spaced
apart from one another.
12. The device according to claim 11, characterised in that the preliminary
opening station (23) comprises at least one guide element (24, 25) with a
10 guide surface (24', 25') inclined towards the transport direction (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
preferably a drive element (24'', 24''') is provided for driving the guide
15 element (24, 25) with the guide 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).
20 13. The device according to claim 12, 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).
27
14. The device according to claim 12 or 13, characterised in that the 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''), wherein preferably the preliminary opening station (23) comprises at
least one vacuum generation unit (27) with a vacuum chamber (27') adjacen5 t
to the guide surface (24', 25') of the guide element (24, 25) with the suction
opening (26).
15. 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
10 transported in a transport direction (5) transverse to its longitudinal extension
(2a) and, during transport, 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), characterised in that the opening device (7)
comprises at least two splaying elements (10) following one another in the
15 transport direction (5) of the tubular bag body (2), wherein each 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), wherein the wedge elements (12; 12', 12'', 12''') of successive
splaying elements (10) have different wedge heights (h) increasing in the
20 transport direction (5) of the tubular bag body (2), wherein the bag sections
(2', 2'') at the open end region (9) of the tubular bag body (2) are splayed apart
during its transport on the transport device (3) by the wedge surfaces (14; 14',
14'') of the wedge elements (12; 12', 12'', 12''') in order to form the bottom
28
opening (8) between the bag sections (2', 2'') at the open end region (9) of the
tubular bag body (2).