EP1593487A2 - Method of manufacturing drawtape bags with elastic drawtape - Google Patents

Abstract

A welding drum(46) has a welding unit(45) with one or more welding rails(47) extending along the drum length. Additional welding bars(50) are fitted to the drum in the area in which a stretchable tensioning band is to be welded onto a film strip bag(16). Welding bars(50) may be moved(E) to different positions around the drum(46) to suit different bags. At least one welding bar may be located on each side of a welding rail(47). The welding machine is supplied by a machine which controls the tension in the stretchable band. Feed tension is controled by a pendulum rocker arm whose mass can be varied. A sensor on the rocker arm is connected electrically to a tension roll for the elastic band. The tension roll is located prior to the rocker arm and acts in conjunction with a pressure roll. A deflecting roll located between the feed unit has a larger diameter in the region of the tension band. The pendulum rocker arm immediately follows a storage roll system with a rocker arm. An independent claim is included for a process for feeding a stretchable band during manufacture of tension band-fitted plastic bags which involves feeding a tension band into a storage roll system via a rocker arm operated by a pneumatic cylinder and then running over a tensioning roll and pendulum rocker arm onto a plastic film strip(16).

Description

The invention relates to a machine for producing drawstring bags from a thermoplastic Plastic film with a welding device containing a welding device, the welding drum having at least one extending the length of the Welding drum extending welding bar is equipped. The invention particularly relates a generic machine with a feeder for a drawstring, wherein the feeding device has a device for influencing the feed tension the drawstring is equipped.

Bags of the type mentioned here are in the bag opening with an elastic Tieback provided to make the perimeter of the bag elastic. With this A design is to be created a possibility, the bag to a container, For example, to attach a trash or a trash can. Such bags have the advantage that when the interior of the container is filled the bag is not in the container falls into it. This is after the insertion of the bag into the interior of the Container, provided with the drawstring upper portion of the bag to the outside over hit the container edge. The elastic drawstring comes on the outside of the container under tension to concern.

A generic bag is disclosed in EP 1 364 892 A1. The one described herein Bag with a bag body that has an opening as well as extending along a perimeter area of the prey body extending in the region of the opening, elastic band which is shorter than the peripheral area in the relaxed state, and the under Release of a compensation area so attached to the peripheral region of the bag body is that the tape does not curl the bag body. The tape is also called Loosely, that is the tape is longer than the mother foil and pulls the bag in relaxed state not together. In particular, this loose introduction of a drawstring in the plastic film web during the production of the bag repeats a problem, since the plastic film web when contracting the drawstring would curl.

In order to adjust the feed tension of the drawstring, from DE 38 21 905 C1 a Device for supplying the drawstrings has become known. This facility owns at the same time a tension and control function for the supplied drawstring. This is the tieback coming from a spool guided over pulleys, on the one hand in the machine frame stored and on the other hand mounted in a swing frame. This is the drawstring meandered around the pulleys. In a described embodiment this frame has two rollers over which the drawstring is guided and in its middle region an adjustable weight. By means of this weight can the tension and controlled feeding of the drawstring by adjusting the frame and weight. It is thus a continuous tension on Tieback available. With this tensile stress superimposed tension is the drawstring supplied to the plastic film web. Feeding a tensioned Tieback but affects adversely on the weld.

A welding device for producing a bag is known from DE 39 13 099 C1. Herein is described how, on the one hand, the cyclical conveying of the plastic film web takes place and how, for another, a stress-free welding in the field of plastic film web can be generated. By a arranged in the welding station Blowpipe is applied to the Kunststoffolienbahn with air. This will be in the Film web reached a lot and a tensionless welding is possible. By the Blowing the air, the web tension of the film web can be safely maintained.

Another generic drawstring bag is known from DE 101 51 843 A1. Described is a bag made of thermoplastic film with a front and a Rear wall, the formation of a filling opening by side welds with each other connected and is formed in each case double-layered in the region of the filling opening. Over the entire bag width extend drawstrings, one of each between the two layers of the front wall and the rear wall is inserted. The drawstrings are welded together at their two ends, the tension band by a in the Plastic film web introduced handle hole is exposed.

An object of the invention is to develop a welding device which allows a more efficient, constructive, simple construction and less expensive welding.
This object is solved by the characterizing part of patent claim 1.

Another object of the invention is a Zugbandbeutelherstellmaschine with a To develop means for feeding the drawstring, in which an extensible drawstring de-energized on the one hand the plastic film web and then the welding device is supplied. The object of the invention is achieved in that the device to influence the supply voltage is provided with a pendulum swing arm. By the inventive use of a pendulum rocker, in the means for feeding of the drawstring, is now created the possibility of tension between the device for influencing the feed voltage and the actual feeding of the tension band to influence the plastic film web. With the invention Pendulum swing can thus the tension between feeder and the actual Insertion area can be influenced in the plastic film web.

This influence on the supply voltage in the tension band can by means of the pendulum swing thereby adjustable on one arm of the pendulum swing arm Weight is appropriate. The pendulum swing arm acts only by means of Gravity on the drawstring. An even more precise influence on the tensile stress can then be made when to the center axis of the pendulum swing a Encoder is arranged. With the rotary encoder acts in Zugbandlaufrichtung before the Pendulum swing arranged pull roller together. The drawstring wraps around the draw roller and is conveyed by means of the draw roller. The rotary encoder forms on the pendulum rocker with the drive motor of the tension roller a control loop. Will now the pendulum swing, which is wrapped in s-shaped at their arms of the drawstring, strong deflected, the drive motor for the tension roller receives a corresponding signal and is braked in this case, since in this case too much drawstring of the plastic film web is supplied.

To the tensionless feeding the provided with the drawstring plastic film web to allow is proposed according to the invention behind the merger for the drawstring and the plastic film web to arrange a deflection roller, from which comes from the film web to be welded to the welding device. According to the invention this pulley has a larger diameter in the region of the drawstring. Due to this change in the diameter in the region of the drawstring in the plastic film web this area, that is the tieback, is accelerated more and more behind the deflection roller relaxed. The larger peripheral speed at the deflection roller causes a pulling in front of the deflection roller and a pressing of the tension band behind the Deflecting. The drawstring is thus fed loose to the welder. Loose means in this context, that on the elastic tension band no tensile stresses act or that the tensile stresses in operation are almost zero.

The invention will be explained in more detail with reference to an embodiment.

Figur 1

einen Beutel mit elastischem Zugband,

Figur 2

einen Zugbandbeutel gemäß dem Schnitt II-II aus der Figur 1,

Figur 3

einen ersten Teil einer Zugbandbeutelherstellmaschine in der Seitenansicht,

Figur 4

eine Detailansicht gemäß dem Schnitt IV-IV auf eine Einrichtung zur Zugspannungsentlastung am Zugband,

Figur 5

einen weiteren Teil der Zugbandbeutelherstellmaschine in der Seitenansicht,

Figur 6

eine Detailansicht einer Schweißeinrichtung zum Verschweißen des Zugbandes im Schnitt VI-VI und

Figur 7

eine Seitenansicht auf Schweißeinrichtung zum kontinuierlichen Schweißen eines Zugbandbeutels.

Show it

FIG. 1

a bag with elastic drawstring,

FIG. 2

a drawstring bag according to the section II-II of Figure 1,

FIG. 3

a first part of a Zugbandbeutelherstellmaschine in side view,

FIG. 4

a detailed view according to the section IV-IV on a device for tension relief on the tension band,

FIG. 5

another part of the Zugbandbeutelherstellmaschine in side view,

FIG. 6

a detailed view of a welding device for welding the drawstring in section VI-VI and

FIG. 7

a side view of welding device for continuously welding a Zugbandbeutels.

FIG. 1 shows a draw-band bag made of a thermoplastic plastic film 1. The drawstring bag 1 consists of a front wall 2 and a rear wall 3, which are connected by side welds 4, 5 at their edges. Of the Bottom 6 of the Zugbandbeutels 1 is formed by the folding of the drawstring bag 1 Plastic film web produced. At least in the region of the filling opening 7 are both the front wall 2 and the rear wall 3 formed double-layered, in particular also shown in FIG. To create a two-ply area, either in the region of the filling opening 7 by folding the respective web edges a seam or the drawstring bag 1 is made of four superimposed webs, so that the front wall 2 and the rear wall 3 each as a whole two-ply are formed. The double-layered region of the filling opening 7 is through Longitudinal welds 8, 9 limited, each of the two layers of the front wall 2 and connect the rear wall 3 together. At the edge of the filling opening 7 are the two Layers of the front wall 2 and the rear wall 3 in each case closed together. This is achieved by the fact that the front wall 2 and the rear wall 3 in the area the filling opening 7 are handled. It is also possible the two layers the front wall 2 and the rear wall 3 at the edge of the filling opening 7 with a not welded longitudinal weld seam welded together.

In the folded area of the filling opening 7 is between the layers of the front wall 2 and the rear wall 3 each a drawstring 10, 11 inserted. The drawstrings 10, 11 extend over the entire bag width and are at their ends by means of the transverse welds 4, 5 welded to the plastic film web. Before introducing the Drawstrings 10, 11 in the region of the filling opening 7 are in the Kunststoffolienbahn Punches 12, 13 have been introduced. Limit additional transverse welds 14, 15 the filling area 7 of the Zugbandbeutels. 1

In the figure 3 is an example of a machine for the production of drawstring bag 1 in the Side view in the supply of the drawstrings 10, 11 shown. The plastic film web 16, which is also called parent sheet 16 is in the direction of arrow P of Machine supplied. Here, the unwinding device for the plastic film web 16 also be part of the machine. The plastic film web 16 passes over Storage roller system 17 to a first punching station 18. In this first punching station 18 vent holes can be introduced into the plastic film web. In the following Punching station 19, the punched-12, 13 in the plastic film web 16th introduced in the region of the filling opening 7. In the following step, the plastic film web, which is present as a folded web opened and the edges of the Zugbandbeutels 1 and the drawstring 10, 11 fed. This feeder for the drawstring 10, 11 is denoted by 20. After feeding 20 of the drawstring 10, 11, the folded plastic film web 16 is brought together again and over a Guide roller 21 fed to a subsequent welding device.

In the lower part of the machine in Figure 3 are two coils 22, 23 with drawstrings 10, 11th shown. By way of example, the tension-free feeding of the drawstring 10 will be described here to be discribed. For the drawstring 11, the same voltage-free supply applies to Feeding unit 20. The drawstring 10 is a storage roller system 24 via a deflection roller 25 supplied with a rocker 26. The swingarm is one with a tensile compressive stress acted upon cylinder 27 connected. By in the cylinder 27th adjustable tension, the tension in the tension band 10 can be adjusted. about a further deflection roller 28, the tension band 10 of another device to influence supplied to the supply voltage.

4 shows a view according to the view IV-IV of Figure 3 is shown. In the FIG. 4 likewise shows the arrow P again, which shows the web running direction of the drawstring 10, 11 reproduces. In the figure 4 is a drive motor 29, a tension roller 30, a Pressure roller 31, a pendulum rocker 32, which is equipped with a rotary encoder 33 as well as various unspecified pulleys reproduced. From the pulley 28th Coming the drawstring 10 is redirected in the direction of arrow P on the draw roller 30. Here, the tension roller 30 is assigned a pressure roller 31, via which the tension band 10th is pressed against the tension roller 30. By this draw roller, the tension of the Tieback 10 from the storage roller system 25 in combination with the pendulum swing 32 are almost eliminated. The pendulum rocker 32 acts on the tension band 10 only by their own weight. The legs 34, 35 of the same length and the same Weight. The adjustment of the variable weight of a pivot 34 of the Pendulum swing arm 32 via a fastened to the leg 34 weight 36. The drawstring 10 wraps around the ends of the legs 34, 35 almost s-shaped. The diversion The ends of the legs 34, 35 takes place via cylindrical rollers or cylindrical pins. The Pad of the tension band 10 at the cylindrical ends 37, 38 is identical, so that always given the same wrap angle of the tension band around the cylinders 37, 38 is. Will now at too fast promotion of the tension band 10, the pendulum swing 32nd strongly deflected, so that the rocker 32 is in the position A, A 'so receives the on the pendulum swing arm 32 located encoder 33 is a corresponding signal directly is forwarded to the control for the drive motor 29. In this loop Now follows a readjustment of the engine, which slows down the draw roller a little. The drawstring 10 is thus stretched again and it does not come to an overhang Tieback 10 in the plastic film web 16. By this invention integration a tension roller 30 with downstream pendulum rocker 32 and control loop 33, 29 consisting from drive motor 29 and rotary encoder 33 is the solution according to the invention fulfilled the task and the drawstring 10 is tension-free of the plastic film web 16 supplied in the feeder for the drawstring 20. Another inventive Advantage is that with relatively simple design means the tension from the drawstring 10 after unwinding from the spool 22, 23 is realized.

As shown in Figure 5, the provided with the drawstring plastic film web 16 a welding unit 39 is supplied. It should be noted that between the feeder 20 and the welding unit 39 an unillustrated system can be inserted, in which the plastic film web 16 from a continuous to a discontinuous Promotion is feasible. In the following description, the discontinuous Promotion needed. In a first welding process, the side welds 4, 5 by means of two welding bars 40, 41 over a bag width L in the plastic film web 16 introduced. In this welding station in the side welds 4, 5 introduced are also welded, the drawstrings 10, 11, see Figure 1. An essential Advantage of the invention is that of the drawstring bag 1 dead can be welded. If a voltage applied to the tension band 10, 11, so could on the one hand by the tension the drawstring 10, 11 tear during welding or on the other hand after welding by the contraction of the drawstring 10, 11th reduce the bag width L by curling the plastic film web 16. Because in the subsequent cycles the Zugbandschweißungen must be made but the Bag width L remain identical, to ensure a reproducible welding result and usable Tieback bag 1 to produce.

Due to the inventive use of the swing arm 32, the tension band is now Loose between the welding bars 40, 41 and can be easily welded to the Muttefolie 16 become.

In addition, the invention proposes to vary the deflection roller 21 in diameter. By changing the diameter of the guide roller 21 in the region of the drawstring 10, 11 results in the promotion in relation to the other roll diameter higher speed. Due to the higher speed, will be at the Side of the feeder 20 for the drawstring 10, 11 pulled on the drawstring 10, 11 and the drawstring 10, 11 pressed in the direction of the welding station 39. This preserves that Tieback 10, 11 a light to mother foil 16 forerun, so that the elastic tension band 10, 11 between the welding bars 40, 41 is arranged loosely, where against the mother foil 16 under a certain to promote the mother sheet 16 necessary voltage for Promotion stands. The change in diameter in the region of the drawstring is but only slightly. A diameter change of only 0.5 mm already gives a noticeable Additional transport of the drawstring area of the drawstring bag 1. For a diameter change of 0.5 mm on a width of about 30 mm results in a feed of about 1.5 mm.

After the side welds 40, 41 are by means of the welders 42, 43 the welds 14, 15 performed in Zugbandbereich. There are always two bags welded at the same time.

FIG. 6 shows the view VI-VI from FIG. 5 again.

In order to produce a wide variety of drawstring bag 1, owns the machine Carriage 44 on which the welding devices 42, 43 adjustable for the drawstrings are arranged. About the carriage 44, the welding means 42, 43 for the Drawbands adjustable in the direction of arrow D.

According to the invention, behind the feed device 20, a welding device 45 be arranged for continuous welding of the plastic film web 16. In this Case would be the feeder 20 for the drawstring 10, 11 directly in front of the welding device 45 may be arranged and the plastic film web 16 of the welding device 45 fed directly over the deflection roller 21. The welding device 45 is made from a welding drum 46 and across the width of the welding drum 46th extending welding bars 47, which at the periphery of the welding drum 46 at a distance L are arranged. Between the welding strips 47 each of the distance L is present, the width of a to be welded Zugbandbeutels 1 and to be generated Cross welds 4, 5 corresponds. With the welding drum 46, the sweatband works 48 together. In this case, the sweatband 48 via deflection and / or drive rollers 49 introduced to the welding drum 46. The sweatband 48 wraps around the Welding drum 46 in this embodiment about 180 °.

According to the invention, it is now proposed, in addition to the welding strips 47 short welding bars 50 in the region of the drawstring 10, 11 to order. Here are the extend Welding bar 50 in length just in the welding drum 46 in that the Tieback welds 14, 15 can be performed. According to the invention the welding bars 50 are variably arranged on the circumference of the welding drum 46. In this case, the welding bars 50 can be adjusted in the direction of the arrow E to to produce a wide variety of drawstring bag 1. It is also conceivable not only to arrange a welding bar 50 next to the welding bars 47, but There may also be two or more weld bars 50 on each side of the weld bar 47 may be arranged.

The plastic film web 16 is fed in the direction of the arrow P of the welding device 45. About a first deflection or drive roller 49, the plastic film web 16 led to the sweatband 48 and thus passes between the welding drum 46 and the sweatband 48. During the passage of the plastic film web 16 through the Welding device 45 is now a continuous welding process. Starting from the Point 51, which defines the welding start, is a continuous welding of the Plastic film web 16 with the drawstring 10, 11 and a simultaneous welding the drawstrings 10, 11 in the region of the openings 12, 13, wherein the additional transverse welds 14, 15 are performed by the welding bars 50. Starting from the Welding start 51, the welding drum moves in the direction of arrow F, so that the Plastic film web 16 during a rotation angle of in this embodiment about 180 ° is welded. It goes without saying that by a change the rotational speed of the welding drum 46 and the conveying speed for the Plastic film web 16, the welding time is changeable. In this embodiment The invention continuously two drawstring bags 1 are welded. At point 52 triggers the welding drum 46 again from the sweatband 48 and the plastic film web 16 and at point 53, the plastic film web continues for further processing promoted.

By the use according to the invention of the welding bars 50 in the area of the welding strips 47 can now waive further welding devices behind the welding drum 46 become. Due to the adjustability of the welding bars and the arrangement of several Welding bars 50 on the circumference of the welding drum 46 are also any drawstring bags 1 can be produced. The embodiment according to FIG. 7 shows a welding drum 46 and a sweatband 48. However, it is also conceivable with counterpressure strips to work. If a different width L of drawstring bags 1 is required, then the welding drum 46 in the welding device 45 is changed in diameter or with a corresponding number of welding bars, any number: 1, 2, 3, 4, 5, etc., which are switched on or off, drove. The same applies to narrower Bag and corresponding to the width L matched diameter of the welding drum 46. Welding takes place via the welding strip 47 and the welding bars 50, wherein Also, the welding bars are 50 welding strips, both 47, 50 with a glow band can be equipped. About the sweatband 48 is on the welding bars 47, 50th the corresponding counter-pressure required for welding is generated.

Claims (12)

Machine for producing draw-band bags (1) from a thermoplastic film (16) with a welding device (45) containing a welding drum (46), the welding drum (46) being provided with at least one welding strip (47) extending over the length of the welding drum (46) ), characterized in that the welding drum (46) in the region of the drawstrings (10, 11) is equipped with at least one additional welding bar (50). Machine according to claim 1, characterized in that the welding bar (50) is arranged displaceably (E) over the circumference of the welding drum (46). Machine according to one of claims 1 and 2, characterized in that at least one welding bar (50) is slidably disposed on each side of the welding strips (47). Machine for producing draw tape bags (1) from a thermoplastic film (16), in particular according to one of claims 1 to 3, with a feed device (20) for a drawstring (10, 11), which is provided with a device for influencing the feed tension (25 ) of the tension band (10, 11), characterized in that the means for influencing the feed tension (25) is provided with a pendulum rocker (32). Machine in particular according to one of claims 1 to 4, characterized in that the weight (36) of the pendulum rocker (32) is adjustable. Machine in particular according to one of claims 1 to 5, characterized in that on the pendulum rocker (32) a rotary encoder (35) is arranged, which is in electrical contact with a draw roller (29) of the tension band (10, 11). Machine in particular according to one of claims 1 to 6, characterized in that the tension roller (29) with a pressure roller (31) for the tension band (10, 11) cooperates and the tension roller (29) in front of the pendulum rocker (32) is arranged. Machine in particular according to one or more of the preceding claims, characterized in that behind the feed device (20) for the drawstring (10, 11) and in front of a welding device (39, 45) a deflection roller (21) is arranged, which in the region of the drawstring (10, 11) has a larger diameter. Machine in particular according to one of claims 1 to 8, characterized in that the pendulum rocker (32) is arranged directly behind a with a rocker (26) provided storage roller system (25) Machine in particular according to one of claims 1 to 9, characterized in that an elastic drawstring (10, 11) is supplied. Machine in particular according to one of claims 1 to 10, characterized in that at least two pendulum rockers (32) for at least two drawstrings (10, 11) are arranged in the machine. Method for feeding a drawstring (10, 11) for producing a drawstring bag (1) with the method steps: Unwinding a drawstring (10, 11) from a spool (22, 23), Feeding the drawstring (10, 11) in a storage roller system (25), wherein the storage roller system (25) via a with a pneumatic cylinder (27) movable rocker (26) is provided and Feeding and inserting the drawstring (10, 11) to and into a plastic film web (16), characterized in that the drawstring (10, 11) behind the storage roller system (25) first via a tension roller (29) and then via a pendulum rocker (23) of the plastic film web (16) is supplied.

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