PLANT FOR MANUFACTURING BAGS FROM TWO LAYERS OF PLASTIC FILM, METHOD FOR OPERATING SUCH A PLANT AND BAG

Abstract

An installation for producing bags from two-layer plastic film includes a film gripper for drawing the plastic film into a tool at a first station, and a rotary conveyor belt for conveying the film through a plurality of stations. The film gripper is designed to guide the plastic film through the first station to a second station.

Claims

1. A plant for manufacturing bags from two layers of plastic film, with a film gripper for drawing the plastic film into a tool at a first station and with a circulating transport belt for transporting the film through several stations, wherein the film gripper is adapted to guide the plastic film beyond of the first station to a second station.

2. The plant according to claim 1, wherein the film gripper is arranged at the transport belt.

3. The plant according to claim 1, wherein the film gripper is arranged slidably along the transport belt.

4. The plant according to claim 1, wherein a feed actuator for the film gripper, independent of the transport belt, is provided.

5. The plant according to claim 1, wherein a second feed actuator for the film gripper, independent of the transport belt, is provided.

6. The plant according to claim 4, wherein the first or the second feed actuator independent of the transport belt is locally secured to a machine frame and is configured to be extended into a circulating path of the film gripper.

7. The plant according to claim 4, wherein the first or second feed actuator independent of the transport belt has a centering means for precisely positioning the film gripper.

8. The plant according to claim 4, wherein the first or second feed actuator independent of the transport belt is coupled or synchronized with a film feed actuator.

9. The plant according to claim 4, wherein the first or the second feed actuator independent of the transport belt is retractable, whereas the film gripper is adapted to move only in the circulatory direction.

10. The plant according to claim 1, wherein the film gripper has a needle for needling the plastic film.

11. The plant according to claim 10, wherein opposite to the needle, a counterblock with a recess flush with the needle is provided.

12. The plant according to claim 1, wherein the film gripper has a stroke actuator adapted to lift a film engagement means with respect to a film level.

13. The plant according to claim 1, wherein the film gripper has an aspiration device for aspirating the plastic film.

14. The plant according to claim 1, wherein the film gripper has a clamping jaw for clamping the plastic film from a top side and from a bottom side.

15. The plant according to claim 1, wherein the transport belt and the film gripper are adapted such that the film gripper is slid by a central electrode block in the circulatory direction from the first to the second station.

16. The plant according to claim 1, wherein a central electrode is arranged at the transport belt.

17. The plant according to claim 1, wherein the central electrode is locally secured to the transport belt.

18. The plant according to claim 1, wherein several film grippers are provided, wherein between them, central electrodes of a use part are provided.

19. The plant according to claim 1, wherein several central electrodes are arranged at a central electrode block.

20. The plant according to claim 1, wherein two film grippers are spaced by the dimension of a feed cycle.

21. The plant according to claim 1, wherein a plurality of stations are arranged along a circulating direction.

22. The plant for manufacturing bags from two layers of plastic film, with a film gripper for drawing the plastic film into a tool at a first station and with a circulating transport belt for transporting the film through several stations, wherein the plant is adapted to couple the film gripper over a first distance with a transport belt feed actuator and over a second distance with a feed actuator independent thereof.

23. The plant according to claim 22, wherein the plant is adapted to couple the film gripper over a third distance with a second feed actuator independent of the transport belt feed actuator.

24. The plant according to claim 1.

25. A method for operating a plant for manufacturing bags from two layers of plastic film, with a film gripper for drawing the plastic film into a tool at a first station and with a circulating transport belt for transporting the film through several stations, the method including the following steps: a. positioning the film gripper for gripping the plastic film in fact by way of a relative movement with respect to the transport belt and/or with respect to a film feed actuator; b. gripping the plastic film; c. drawing the plastic film into the tool at the first station by means of the film gripper, in fact coupled or synchronized with the film feed actuator; and d. drawing the plastic film further to the second station by means of the film gripper, in fact coupled or synchronized with the transport belt.

26. The method according to claim 25, wherein the positioning of the film gripper for gripping the plastic film (step a) takes place by sliding the film gripper forward along the transport belt and in fact by means of a first feed actuator which drives back afterwards.

27. The method according to claim 25, wherein gripping (step b) takes place by needling the plastic film on a needle at the film gripper.

28. The method according to claim 25, wherein drawing of the film into the first station (step c) takes place by means of a second feed actuator which is directly connected mechanically to a film feed actuator.

29. The method according to claim 25, wherein after drawing the plastic film into the first tool, the second feed actuator disengages the plastic film and drives back.

30. The method according to claim 25, wherein after disengagement of the second feed actuator, the film, driven by the film gripper, is transported further by a transport belt feed actuator.

31. The method according to claim 30, wherein a central electrode block shoves the film gripper with its front face.

32. The method according to claim 25, wherein the film gripper grips the plastic film on the level of a product to be manufactured with two successive use parts being separated from one another without waste strips.

33. A medical bag filled with a liquid, manufactured with a plant according to claim 1.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0087] In the following, the disclosure will be explained in more detail using an example of embodiment with reference to the drawings wherein:

[0088] FIG. 1 schematically shows a spatial view of part of a plant for manufacturing medical bags, having a circulating transport belt, a first feed actuator, a second feed actuator, a vertical stroke actuator and a feed beam, in an engagement position of the first feed actuator, that is, at an end of a first feed,

[0089] FIG. 2 shows, in a view as in FIG. 1, a chronological subsequent situation in which the vertical stroke actuator is active,

[0090] FIG. 3 shows, in a view analogous to FIGS. 1 and 2, a chronological subsequent situation in which the vertical stroke actuator is withdrawn,

[0091] FIG. 4 shows, in a view analogous to FIGS. 1 through 3, on a slightly larger scale, a chronological subsequent situation in which the second feed actuator has been active, and

[0092] FIG. 5 schematically shows a detail of the situation in FIG. 3 from a slightly lower perspective view.

DETAILED DESCRIPTION OF THE DRAWINGS

[0093] Plant 1 in the Figures substantially comprises different workstations (not shown) which share in the tasks for manufacturing a medical bag. For instance, there is a roller feed in which two rollers of plastic film are provided. Such a station normally represents the beginning of the film's path through the plant in the machine direction.

[0094] To keep the tensile stress during introduction in the first machining tools as constant as possible, a dancer roll arrangement can be provided.

[0095] A preheating station can be provided.

[0096] The first workstation in a plant of the kind described here by way of example is normally a welding tool, even if the welding tool as such is not shown.

[0097] The welding tool can be, for instance, a combined welding and cutting tool, or welding or even pre-welding can be performed by itself. For instance, plants are known wherein the tubes which will form ports in the medical bag later on are first only temporarily adhered thermally to the film.

[0098] In most cases, this will be followed by post-welding stations, transfer stations, filling stations and/or labeling or printing stations for the medical bags.

[0099] The first workstation 2 (the position of which is indicated but which is not shown) is located, just like the other workstations, alongside the circulating transport belt 3. The circulating transport belt 3 is driven by a motor (not shown) in the machine direction 4, 5, 6.

[0100] On the transport belt 3, a plurality of central electrode blocks 7 (numbered by way of example) are secured by fixed securing means such as screws 8 (numbered by way of example).

[0101] Two central electrode blocks 7 each form one central electrode block pair 9 (numbered by way of example) of a use part in the manufacturing of medical bags. In a machine cycle corresponding to the length of a use part, two central electrode holders will therefore hold one use part and four central electrodes will be able to weld in small tubes between the two film layers in manufacturing of the bags.

[0102] Holding of the bags by means of central electrode blocks is already known from the state of the art, for instance from EP 2 026 951, and will therefore not be described here in detail.

[0103] In a space 10 (numbered by way of example) between two adjacent central electrode block pairs 9 of a use part, a needle gripper block 11 (numbered by way of example) is located. The needle gripper block 11 substantially comprises a gliding body 12 which is arranged slidably in the longitudinal direction on the transport belt 3 and a needle gripper 13 arranged on a vertical carriage 14 at the gliding body 12.

[0104] On a front side 15 of the transport belt 3, at the inlet of the straight path, there is a first feed actuator 17 located after a direction change mechanism 16. The first feed actuator 17 substantially comprises a stationary cylinder 18 and a first feed piston 19 which can be moved out of the cylinder 18 in a linear direction. The first feed actuator 17 is arranged in a horizontal moving direction such that the circulating central electrode blocks 9 can freely pass by the first feed actuator 17 if the first feed piston 19 is retracted, whereas the first feed piston 19 can in any case extend into the track of the gliding bodies 12 of the needle gripper blocks 11.

[0105] The extension speed of the first feed piston 19 is higher than the feed velocity of the transport belt 9 during the intermittent feed.

[0106] Also, a feed and a retraction of the first feed piston 19 can take place in less time than is needed for the pause in the cycle between two feeds of the plant.

[0107] At a first ejection end 20 of the first feed piston 19, that is, at the downstream end of a first feed distance 21, there is a second feed actuator 22 which can be moved in the linear direction, for instance, along a rail 23, via a second feed distance 24 along the machine direction 4 on the front side 15 of the transport belt.

[0108] For this purpose, the second feed actuator 22 substantially comprises a driving body 25 attached to the rail 23 and an extendable centering pin 26 which is attached to the driving body 25 so that it can be vertically driven upward and downward.

[0109] At a beginning of the second feed distance 24, there is also a vertical stroke actuator which is secured to the plant so as to be stationary. The vertical stroke actuator 27 substantially comprises a drive unit 28 and a vertical pusher 29.

[0110] The vertical pusher 29 is arranged such that in case of a vertical upward stroke, it definitely hits the vertical carriage of the needle gripper block 11 currently located at the ejection end 20 of the first feed distance 21, precisely the protruding driver 30 of the vertical carriage.

[0111] The plant operates as follows:

[0112] The transport belt 3 is intermittently moved through the plant in the machine direction 4, 5, 6.

[0113] Consequently, the central electrode blocks 7 are moved through the plant 1 in the machine direction 4, 5, 6 with the same clock pulse.

[0114] The foremost central electrode block 7 of each central electrode block pair 9 or of any larger or smaller number of central electrode blocks within a use part shoves with its front face the needle gripper block 11, which can slide freely along the transport belt 3, along its gliding body 12 in the machine direction 4, 5, 6.

[0115] That is, an arbitrarily chosen specific central electrode block 31 shoves an arbitrarily chosen needle gripper block 32 with its front face 33, along a back side 34 of the circulating transport belt 3 and around the direction change mechanism 16.

[0116] At the output of the direction change mechanism 16, consequently the exemplary needle gripper block 32 crosses the path of the first feed distance 21 of the first feed piston 19 of the first feed actuator 17. As soon as this happens, the first feed actuator 17 deploys the first feed piston 19. Then, with its front face, which can be buffered, for instance, with an elastomer, or which can assume a secure gripping position at the exemplary needle gripper block 32 by means of a magnet or similar, it pushes the exemplary needle gripper block 32 to a precisely predefined position at the output end 20 of the first feed distance 21. This position is set so as to be suited for needling of the film sheet or double-layer film sheet arriving from a direction 35.

[0117] FIG. 1 shows the exemplary needle gripper block 32, which has already been advanced, at the output end 20 of the first feed actuator 17, that is, in precisely the correct position for needling of the film.

[0118] There, the vertical stroke actuator 27 and the second feed actuator 22 become active (see FIG. 2):

[0119] The second feed actuator 22 drives its centering pin 26 vertically upwards, and thus engages a centering element, for instance a spherical concave surface, at a bottom side 36 of the exemplary needle gripper block 32. Independently of the precision of the feeding movement of the exemplary needle gripper block 32, caused by the first feed actuator 17, the position of the needle gripper 13 on the exemplary needle gripper block 32 is predictable with maximum precision after centering on the centering pin 26.

[0120] The first feed actuator 17 which has brought the exemplary needle gripper block 32 in the centering position for the second feed actuator 22 has thus performed its task and retracts the first feed piston 19 so that it is available for the next cycle.

[0121] By way of a vertical upward deployment of the vertical pusher 29, the needle gripper 13 of the exemplary needle gripper block 32 is moved upwards with its gliding body 12. The position along the machine direction 4, 5, 6 remains unaltered and therefore set very precisely. The needles of the needle gripper 13 now engage the film sheet (not shown).

[0122] The driving body 25 of the second feed actuator 22 is fixed securely to a film feed beam 37 or to the frame thereof.

[0123] In the situation shown in FIG. 2, the needle gripper 13 thus engages the film. At the same time, the exemplary needle gripper block 32 is set for film feed.

[0124] The vertical stroke actuator 27 then again pulls the vertical pusher 29 vertically downward and releases itself from the driver 30 of the exemplary needle gripper block 32 (see FIG. 3).

[0125] In the subsequent step (see FIG. 4), the film feed then drives a cycle together with the belt feed of the transport belt 3. During this cycle, the second feed actuator 22, driven by or in any case mechanically coupled to the film feed beam 37, draws the respective film by means of the needle gripper 13 into the first processing station, for instance the tool of a welding station, in particular a combined welding and cutting tool for welding at least part of the contour and/or of the ports of a medical bag, or in the present case, of two medical bags within a use part with two ports each.

[0126] The position of the needle gripper 13 is precisely known. Therefore, the centering pin 26 can again be moved vertically downward out of the centering means of the exemplary needle gripper block 32. At the same time, the foremost exemplary central electrode block 31 of the next use part has moved up and now abuts at the exemplary needle gripper block 32 with its end face 33 directly or by means of a spacer.

[0127] Starting from this situation, the film can be moved easily by means of the feed of the transport belt 3.

[0128] With this procedure, the needle gripper 13 of each needle gripper block 11 remains engaged even downstream of the first processing station (shown in FIG. 4), which allows maximum precision in guiding the film through the various stations.

[0129] After the centering pin 26 has retracted, the film feed beam 37 can drive back and is again available for feeding in the next advancing film.