CA2313072C

CA2313072C - Device for opening tubular bag bodies

Info

Publication number: CA2313072C
Application number: CA002313072A
Authority: CA
Inventors: Franz Starlinger Huemer; Gerhard Apfler
Original assignee: Starlinger and Co GmbH
Current assignee: Starlinger and Co GmbH
Priority date: 1998-10-05
Filing date: 1999-10-04
Publication date: 2006-12-12
Anticipated expiration: 2019-10-04
Also published as: EP1035967B1; KR100461214B1; WO2000020195A1; CA2313072A1; PT1035967E; CZ20001813A3; EP1035967A1; BG104454A; BR9906847A; ID26825A; BG63529B1; JP2002526285A; JP3753941B2; TR200001537T1; ATA165798A; AU6181199A; AT406755B; CZ294286B6; KR20010032340A; DE59902331D1

Abstract

The invention relates to a device for opening tubular bag shapes which are open at at least at one end, comprising at least one slide which can be introduced into an open end of a bag between the bag walls, in order to at least partially fold over at least one end area of a bag wall. According to the invention, the at least one slide (3) can be move d in and out of the bag end to be opened by means of at least one, driven cam (9) which can be moved along a predetermined path (8) and which engages with the slide (3). The slide (3) preferably takes a circular path (4), said circular path comprising a section which runs parallel to a bag-transporting device. The speed of transportation of the bags (2, 2a) on the conveyor device (1) and that of the slide (3) around the circular path are equal.

Description

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DEVICE FOR OPENING TUBULAR BAG BODIES
The present invention relates to a device for opening tubular bag bodies which are open at least at one end, comprising at least one slide, which may be introduced into one open end of a bag body between walls of the bag body, in order to at least partly fold over at least one end region of a bag body wall, the at least one slide being movable into the bag body end to be opened and out thereof by means for reciprocating a respective slide.
The production of bags usually comprises providing tubular material which is either obtained by producing tubular material webs or by joining the longitudinal edges of flat material webs so as to obtain a tubular configuration, cutting the tubular material so as to obtain bag bodies of suitable length, and forming a bag bottom by appropriately folding over and closing one end of the bag body. A bag having a rectangular bottom produced in this way is usually called a box-type bag by specialists in the field. In order to form the bottom of such a box-type bag, the end part of one of the two bag body walls lying one on top of the other in a flattened bag body is folded over along a folding line running transversely to the longitudinal axis of the bag body, so that the end of the bag body takes a hexagonal folding configuration with two parallel seams opposing each other and two pairs of parallel folding edges opposing each other. By folding the two seams towards each other and securing the folding lobes comprising the seams to each other or to a cover sheet the bag body is provided with a bottom which takes a rectangular configuration when the completed bag is folded apart. It is also possible to apply a valve sheet before folding the seams towards each other, which valve sheet takes a tubular configuration when folding the bag body end to its final shape.
At present substantially two systems are known for folding the open end of a bag body over in such a way that the bottom of a box-type bag may be formed. It may be mentioned that specialists usually call this folding-over "opening" of the bag body.

The first known system comprises a continuously movable spreading mechanism which is easily damaged and requires extensive adjustment and re-adjustment operations.
The second system comprises an intermittently movable conveyor belt, on top of which the bag bodies, the longitudinal axes of which are oriented transversely to the conveying direction, are transported to an opening station, where the conveyor belt stops. At the opening station the seams of the bag body ends to be opened are pulled somewhat apart, and a slider mounted so as to be movable in transverse direction, but otherwise immobile, moves into the bag body end and folds one part of the upper bag body wall rearwardly, which results in the above hexagonal folding configuration. The folding line along which the slider folds the bag body wall is defined by a girder, which is disposed above the bag bodies in the direction of transport of the latter, and which, upon stopping of the belt, is lowered onto the bag body while at the same time holding it, the slider inside the bag body moving across the girder. After folding is completed the slider is withdrawn, the girder is raised, and the conveyor belt with the folded bag body may continue its travel. The slide is reciprocated in a generally horizontal plane, which corresponds to that of the bag body on the conveyor belt, by means of a pneumatic system comprising piston and cylinder. A disadvantage of this assembly primarily resides in the fact that intermittent operation is necessary, which leads to high wear and high energy consumption and moreover limits the production speed, as the bag body has to be kept stationary during all of the slide movement. Further disadvantages of this known system are discussed later in the specification in the course of the description of the present invention.
Another conventional device is described in German Patent Application No.
1.511.021, which discloses a process and device for the manufacture of the cross bottoms in lengths of tubular material for forming cross-bottom bags. This continuously operating device comprises slides guided along an orbital path having some sections in parallel to the direction of transport of the bag bodies, slides and bag bodies moving at the same speed. In order to make it possible to introduce the slides into the open ends of the bag _2-bodies, they are guided at least for some time along a path inclined with respect to the horizontal line, which path takes the form of a guide bar against which the slides roll off by means of a control roller.
The present invention provides a device of the above kind by which the disadvantages of the state of the art are overcome and which is sturdy, reliable and needs little maintenance and permits a production speed by far higher than that of systems known today.
These advantages are achieved by a device of the above kind, wherein the means for reciprocating a respective slide comprises at least one driven cam, which can be moved along a predetermined path and engages the slide so as to move it back and forth. This construction according to the invention is particularly suitable for continuous operation, as apart from the reciprocating movement of the slide, the device primarily relies on rotational movements, which entrain considerably less wear and reduced driving energies as compared to translational movements as employed, for instance, in the device of German Patent Application No. 1.51 1.021.
In a preferred embodiment of the invention the at least one cam is mounted on a driven chain or belt, running around wheels or pulleys, the wheels defining a first orbit path section approaching the bag body, a second orbit path section leading away from the bag body, and a third orbit path section forming a cam return section.
Optionally a fourth orbit path section having a substantially constant distance to the bag body end to be opened may be provided between the first and second orbit path sections. A
cam moving in the first orbit path section moves the slide associated thereto into the open end of the respective bag body, while the cam, when arriving at the second orbit path section, retracts the slide. The fourth orbit path section serves the purpose of keeping the slide in rest position with respect to the bag body for a predetermined period of time while additional process steps may be carried out on the bag body.

In order to be able to change the sequence in time of the movements of the respective slide, it is advantageous for the positions of at least one of the wheels or pulleys of the means for reciprocating a respective slide to be adjustable.
An advantageous embodiment of the invention is characterised in that each slide has a guiding path for sliding engagement with cams. The guiding path of each slide for sliding engagement with the cams may favourably be a U-beam with open ends fixedly attached to the slide, the longitudinal axis of which is oriented at right angles with the direction of reciprocation of the slide.
Although the slides may be fixedly mounted at a working station, the full scope of the advantages of the invention is exploited only if the slides themselves move in congruity with the bag bodies to be opened. Thus a preferred embodiment furthermore provides for a conveyor device for transporting the bag bodies and a drive for moving the slide along an orbit path, the drive of the conveyor device and the drive for moving the slide along the orbit path being synchronised with each other, so that in operation, the speed of transportation (arrow A) of the bag bodies on the conveyor device is substantially the same as the speed (arrow C) of the slide along the orbit.
It is basically desirable to arrange at least two slides in equal distances from each other along the orbit path so as to exploit the advantages of the system. Otherwise long distances would have to be kept between individual transported bag bodies so as to give the slide enough time to return to its initial position in the orbit path.
Providing a plurality of slides also makes it almost irrelevant how much time an individual slide needs to open a bag body, as this time is to be divided by the total number of slides used and may thus be reduced arbitrarily.
In order to make it possible to use several moving slides equally spaced from each other along their orbit with a common cam drive, the speed of the chain or the belt with the cams is adjusted so as to be higher than that of the slides along the orbit path.

Advantageously the drive for moving the slide along the orbit path comprises a chain running around gearwheels or a belt running around pulleys, the chain or belt being connected to the slide and at least one of the gearwheels or pulleys being driven by a motor.
Least energy consumption and minimum wear of the device according the invention for opening tubular bag bodies are achieved by using continuously operating drives as the drive of the conveyor device and the drive for moving the slide along the orbit.
The orbit path for the slides may be defined by a rail where the respective slides are mounted so a to be slidable. Advantageously a device for slidably mounting the slide on the rail comprises a bush and a shaft slidable therein, either the bush or the shaft engaging the rail by means of rollers or sliding surfaces, and the shaft or the bush being connected to the slide.
While with known systems the slide normally consists of a plate which has to be replaced as a whole whenever the size of the bag bodies changes, a further embodiment of the device for opening bag bodies according to the invention provides for each slide to comprise a crossbeam and at least two slide fingers attached thereto, preferably adjustable as to their mutual distances and lengths. Depending on the desired dimensions of the bag bottoms they are adjusted as to their distance (thus defining the longitudinal edge of the bottom) and to their length (thus defining the width of the bottom together with the slide travel). Thus it is not necessary to replace the slide when changing the size of the bag bodies.
As mentioned, the state of the art provides for the slide and the bag bodies to lie in the same plane. This has the undesirable effect that, when opening the bag bodies by the slide, in the folded condition of the bag body up to four material layers are lying on top of each other, while there is just one layer in other portions. This differences in >~

thickness creates substantial problems during further processing of the bag bodies. The present invention also provides a solution for this problem in that with one embodiment the bag bodies are arranged transversely folded on the conveyor device for the bag bodies, wherein the bag body portion extending from the transverse folding line in the direction towards the slide substantially lies in the plane of reciprocating movement of the slide, while the bag body portion extending from the transverse folding line in the direction away from the slide lies in a plane forming an angle, preferably an approximately right angle, with the plane of reciprocating movement of the slide. This measure assures that a maximum of two material layers of the bag body lie one on top of each other after folding.
The invention will now be described by way of example with reference to the drawings, wherein figure 1 shows a schematic side view of an embodiment of the device for opening tubular bag bodies according to the invention, and figure 2 shows a schematic plan view of the same device, the conveyor belt with the bag bodies being omitted in the second figure.
The following description will, unless explicitly stated otherwise, refer to both figures 1 and 2 at the same time. The illustrated device for opening tubular bag bodies according to the invention comprises a conveyor belt 1, on top of which bag bodies 2, 2a are fixed by suitable means, for instance by vacuum. The conveyor belt continuously moves in the direction of arrow A at constant speed. With the exception of an end region thereof which is to be formed into the bag bottom, the bag bodies lie in horizontal orientation on the conveyor belt, their longitudinal axes being directed transversely to the direction of transport A. Said end region of each bag body 2, 2a is folded vertically downwardly and is suspended above one of six slides generally designated as 3. (In figure 1 just two slides are illustrated for reasons of clarity.) The slides 3 are slidably attached to a rail 4, which has two opposing straight sections 4a, -~b connected to each other at their ends by two semi-circular sections 4c, 4d.

Sliding engagement of each slide 3 with rail 4 is achieved by means of four rollers 31, two of which respectively engage one of two opposing longitudinal edges of rail 4. The rollers 31 are rotatably attached to the front face of a slide head 33, a shaft 34 extending downwardly from the opposite face thereof. A bush 35 is slidably mounted on the shaft 34. This bush 35 carries a guiding path taking the form of a horizontal U-beam having open ends, as well as a cross-beam 39, from which slide fingers 36, 37 taking the form of oblong narrow plates extend vertically upwardly in spaced relation to each other. The slide fingers may be attached to the cross-beam 39 so as to be adjustable.
The U-beam 38 and the cross-beam 39 may also be formed as an integral unit.
Below the semi-circular sections 4c, 4d of rail 4 and concentrically therewith, two wheels 5, 6 having vertical rotational axes 5a, 6a are arranged. At least one of wheels is driven by a motor not illustrated. Both wheels 5, 6 are encircled by a chain 7, which is moved in the direction of arrow C. The speed of chain 7 is the same as that of conveyor belt 1. Chain 7 firmly interlocks with a protrusion 32 of each slide, thus pulling the respective slide 3 along. The slides 3 are distributed at equal intervals along chain 7 and thus along rail 4, the distance between two slides being equal to the distance between two bag bodies on the conveyor belt. By appropriate control it is furthermore ensured that during its movement along section 4a of rail 4, each slide faces one bag body on the conveyor belt 1.
A separate drive is provided in order to achieve movement of bush 35 and thus of slide finger 36, 37 along shaft 34. This drive consists of a chain 8 running around four wheels 10, 11, 12, 13 having horizontal rotational axes. At least one of the four wheels is driven so that chain 8 is moved in the direction of arrow B at a speed greater than that of conveyor belt 1 and chain 7. The four wheels 10, 11, 12, 13 and thus chain 8 lie in a vertical plane approximately below the longitudinal border 1a of the conveyor belt. The wheels 10, 11, 12, 13 divide the chain 8 encircling them into a first upwardly inclined section 8a, a second downwardly inclined section 8b, a third section 8c running in parallel to the longitudinal border 1 a of conveyor belt 1 but opposed thereto, and finally a fourth section 8d running in parallel to the third section and adjacent to the conveyor belt 1. Chain 8 has three cams 9 equally spaced from each other.
In the following the operation of the device will be described.
First the conveyor belt 1 and the chains 7 and 8 are set in motion. Bag bodies are supplied on the conveyor belt at predetermined intervals, and synchronised therewith the slides 3 move horizontally around rail 4. When a first slide reaches a position close to wheel 13, a cam 9 of the chain 8 engages the front open end of U-beam 38 of the slide. This happens although the absolute speed of chain 8 is higher than that of chain 7, while the speed component of chain 8 in parallel to chain 7 in the inclined orbit section 8a is smaller than the absolute speed of chain 7. This means that slide 3 catches up with and overtakes cam 9 in section 8a, which is why the cam first enters the front end of U-beam 38 of the slide and then travels rearwards therein, while at the same time raising the slide because of the upwardly inclined orientation of orbit section 8a.
Thus the slide fingers get into engagement with the open end of the bag body facing towards them and in the course of this fold the wall of the bag body which can be seen in front in the drawing upwardly along a folding line defined by a ruler 15 positioned above the longitudinal border 1a of the conveyor belt and thus also above the bag body.
The rear wall of the bag body may be compfete!y or partly sucked by a vacuum band seen behind it in the drawing and running along, so as not to be folded therewith.
Before the cam 9 may leave the U-beam 38 at its rear end, it has reached wheel 10 and changes into a movement along section 8d. The slide fingers 36, 37 have now reached their highest position and maintain it as long as cam 9 is in section 8d. The end of the bag body has adopted a hexagonal folding configuration, as shown at bag body 2a. In this condition it is possible, if necessary, to adhere or weld-on a valve sheet. In the section 8d in parallel to the conveyor belt the cam again has a higher speed than that of the orbital movement of the slide, thus travelling to the front of U-beam 38 again.
_g_ s In the course of the movement of the cam in section 8d the next slide already reaches the position at wheel 13 and gets into engagement with another cam 9 of chain 8. The movement of this second slide and all further slides take place as described and needs no further explanation.
Again discussing the movement of the first slide, cam 9, before leaving the U-beam of the slide at its front end, reaches wheel 11 and adopts the movement given by section 8b of chain 8, which is inclined downwardly, i.e. away from the transport device for the bag bodies, also pulling the slide downwardly, the slide fingers of which finally are disengaged from the bag body. In the position where chain 8 turns around on wheel 12 the cam 9 finally leaves the U-beam 38 through its rear open end and moves along section 8c back to wheel 13, where it engages another slide 3. After disengaging from cam 9 the first slide 3 moves straight on for a certain distance, to turn around at rail section 4c.
If retraction of the slide fingers immediately after they have reached their position of maximum extension without remaining in the extended position is considered to be sufficient, it is also possible to omit one of the two wheels 10 or 11 and thus the orbital section 8d of chain 8.
_g_

Claims

1. A device for opening tubular bag bodies which are open at least at one end, comprising at least one slide, which may be introduced into one open end of a bag body between walls of the bag body, in order to at least partly fold over at least one end region of a bag body wall, the at least one slide being movable into the bag body end to be opened and out thereof by means for reciprocating a corresponding slide, characterised in that the means (8-13) for reciprocating a respective slide (3) comprises at least one drive cam (9) movable along a predetermined path (8) and engaging the slide (3) in order to move it back and forth.

2. The device for opening tubular bag bodies according to claim 1, characterised in that the at least one cam (9) is mounted at a driven chain (8) or a belt, running around wheels (10, 11, 12, 13) or pulleys, the wheels defining a first orbit path section (8a) approaching the bag body, a second orbit path section (8b) leading away from the bag body, and a third orbit path section (8c) forming a cam return section.

3. The device for opening tubular bag bodies according to claim 2, characterised in that a fourth orbit path section (8d) having a substantially constant distance to the bag body end to be opened is provided between the first (8a) and second (8b) orbit path sections.

4. The device for opening tubular bag bodies according to any one of claims 2 or 3, characterised in that the positions of at least one of the wheels (10,11, 12, 13) or pulleys in the device for reciprocating a respective slide are adjustable.

5. The device for opening tubular bag bodies according to any one of claims 1 to 4, characterised in that each slide has a guiding path (38) for sliding engagement with cams (9).

6. The device for opening tubular bag bodies according to claim 5, characterised in that the guiding path of each slide for sliding engagement with the cams (9) takes the form of a U-beam (38) having open ends and attached to the slide, the longitudinal axis thereof being arranged at right angles with the direction of reciprocation of the slide.

7. The device for opening tubular bag bodies according to any one of claims 2 to 6, characterised in that furthermore provision is made for a conveyor device (1) for transporting bag bodies and a drive (5, 6, 7) for moving the slide (3) along an orbital path, the drive of the conveyor device (1) and the drive (5, 6, 7) for moving the slide along the orbit path being synchronised with each other, so that in operation the speed of transportation (arrow A) of the bag bodies on the conveyor device is substantially the same as the speed (arrow C) of the slide (3) along the orbit path.

8. The device for opening tubular bag bodies according to claim 7, characterised in that the speed at the chain (8) or the belt with the cams (9) is adjusted in such a way as to be higher than that of the slide around the orbital path (4).

9. The device for opening tubular bag bodies according to claim 7 or claim 8, characterised in that the drive for moving the slide along the orbital path comprises a chain (7) running around gearwheels (5, 6) or a belt running around pulleys, the chain or the belt being connected to the slide and at least one of the gearwheels or one of the pulleys being driven by a motor.

10. The device for opening tubular bag bodies according to any one of claims 7 to 9, characterised in that the drive for the conveyor device (1) and the drive (5, 6, 7) for moving the slide along the orbital path are continuously operated drives.

11. The device for opening tubular bag bodies according to any one of claims 7 to 10, characterised in that a plurality of slides (3) are provided, distributed at equal distances along the orbital path (4).

12. The device for opening tubular bag bodies according to any one of claims 7 to 11, characterised in that the orbit path is defined by a rail (4) where respective slides (3) are slidably mounted.

13. The device for opening tubular bag bodies according to claim 12, characterised in that means for slidably mounting the slide on the rail (4) comprises a bush (35) and a shaft (34) slidable therein, one of the bush and the shaft engaging the rail (4) by means of rollers (31) or sliding surfaces and the other being connected to the slide.

14. The device for opening tubular bag bodies according to any one of claims 1 to 13, characterised in that each slide (3) comprises a crossbeam (39) and at least two slide fingers (36, 37) attached thereto, preferably adjustable as to their mutual distance and lengths.

15. The device for opening tubular bag bodies according to any one of claims 7 to 14, characterised in that the bag bodies are arranged transversely folded on the conveyor device for the bag bodies, the bag body portion extending from the transverse folding line in the direction towards the slide substantially lying in the plane of reciprocating movement of the slide, while the bag body portion extending from the transverse folding line in the direction away from the slide lying in a plane forming an angle, preferably approximately a right angle, with the plane of reciprocating movement of the slide.