EP0847922B1 - Apparatus for strapping packages - Google Patents

Description

The invention relates to a device for strapping of packages according to the preamble of the claim 1.

For strapping machines of the aforementioned type is it - e.g. from EP 0 596 303 A1 - known, the strapping from the strapping stock through a the strapping on opposite one another Side pair of rollers driving by friction (Shot roller pair 18 in EP 0 596 303 A1) into the machine or to shoot into the strapping channel. Once the leading strapping end after circulation through the strapping channel and around the package in a strapping clip the strapping tool has to be accommodated to tighten the package before the strapping fastener can be done. This is at known devices either a second, in opposite directions driven roller pair (puller roller pair 16 in EP 0 596 303 A1), or the one-shot roller pair can reverse and that way Pull the strapping back and put it around the package tighten.

With the help of this at least pure friction drive are however only certain strapping tension to achieve, so that devices of this type mainly used to make relatively soft, compressible packaged goods taut with the strapping agent to span.

For higher strapping tension on the Applying the package is appropriate for the machine EP 0 596 303 A1 also has a drum-shaped one Strapping pretensioner 17 present there between the weft roller pair and the pull roller pair, is arranged. For a more detailed explanation of a such 'high-tension drum' be on the US 4,605,456. From this patent there is a rotationally drivable tension drum known a diametral strap passage gap has in the rest position of the tensioning drum in the strapping conveying direction is oriented so that the strap runs freely through the gap can. As soon as increased tension on the strapping is to be applied, this tension drum driven with the consequence that the strapping on the peripheral surfaces of the drum segments and after turning through 180 ° on itself itself is wound up. The tension drum tensions that Strapping according to the principle of belt friction, can, however, in contrast to the described Friction roller pairs a much higher tension generate in the strapping.

The tensioning device by means of such However, the tension drum has the fundamental disadvantage that that the slip between the strapping and the tensioning drum only after an angle of rotation of over 180 °. This results in the effect that with less compressible pieces of strapping a high strapping tension with the Tension drum cannot be applied because that Strapping should not be withdrawn as far can that through a correspondingly large wrap angle the tension drum these forces are generated could.

DE-B-2 050 833 is a tensioning device for tapes made of plastic, textiles and the like known. Here is a winding head with two identical ones and pivotable clamp bodies are provided. The rotary drive of the winding head for tensioning the Strapping tool is made using a manually operated one Lever. Even with such an arrangement of Clamping bodies takes place between the sprags and the strapping a slip takes place only after one Angle of rotation of the tensioning drum canceled by more than 180 ° becomes.

Starting from a strapping device accordingly the features of the preamble of the claim 1 and thus corresponding to US 4,605,456 present invention primarily and essentially the task of such a device to improve so that even when generating high tension in the strapping material only low Tensioning distances are available, high strapping tension applied to the package can become, in particular also less compressible Packages can be strapped very tightly.

Another object of the invention is that Cycle times of a machine with a tension drum increase, i.e. a larger number of straps per Allow time unit.

To solve in particular the first-mentioned task serve the features of claim 1. The strapping device is accordingly characterized by that the first drum segment is rigid and that second drum segment relative to the first drum segment is narrowing and is movable at the end its movement together with the first drum segment forms a strapping clamp.

According to the invention, the drum segments form the tensioning drum from a strapping clamp. Thereby the tensioning drum carries the strapping tool Tensile forces not frictionally, but force or clamp-on. That means that the strapping tool Retracting force exerted significantly increased can be and above all much earlier and not only after wrapping around the drum segments 180 °. One with such a "rotating strapping clamp" equipped strapping device is therefore able to compress even little Packages in which the strapping is tightened the strapping was pulled back only a short distance can be strapped tightly.

At the same time with the rotating strapping clamp the further hereditary advantage achieved that the previous strapping abrasion caused by the Slip inevitably occurred, drastically reduced is. This results in the advantage of longer operating times the machine up to a required maintenance.

A further development of the invention provides that the movable drum segment solely due to the Traction of the wrapping strap in Clamp position is movable. The invention goes here assume that the strapping with the rotary motion the tension drum from its extended position occupies a substantially S or Z-shaped position and the angles formed at the entry and exit or from the strapping passage gap are forces on the movable drum segment to transfer it against the other drum segment to form a strap clamp move. With these according to the invention An automatically acting, solely from the strapping or its wrapping controlled strapping clamp created, too whose function requires no special drive means are.

The movable drum segment is therefore preferred from its the strapping passage defining position against a spring force in Movable clamping position. The spring force ensures that after relieving the moving drum segment by relaxing the strapping the movable Drum segment automatically returns to the starting position can move in the strapping passage gap free is.

Regarding the aspect, the machine typical She sees increasing cycle times for strapping Invention before that between the tension drum and Strapping device a controlled Strapping clamp is arranged, the strapping after tensioning by the tension drum holds while the strapping head forms the strapping closure and the tensioning drum reverses in the starting position. The difference to do this in the prior art Tension drum maintain its tension position as long as the strapping device with the Strapping fastener formation was concerned. Now can already reverse the tension drum to ready for the next strapping process stand. The slower sequential mode is according to the invention by a faster working parallel operating mode has been replaced.

Fig. 1

eine Umreifungsmaschine in schematischer Ansicht und

Fig. 2 bis 6

die Umreifungsmittel-Spanneinrichtung mit Bezug zum Umreifungsmittel-Verschlußaggregat in einzelnen, prägnanten Stufen eines Umreifungsvorgangs.

Further advantageous and expedient training and further developments of the subject matter of the invention are specified in the other subclaims. Otherwise, the invention is best understood from the following explanation with reference to an embodiment shown in the drawings. The drawings show:

Fig. 1

a strapping machine in a schematic view and

2 to 6

the strapping device with reference to the strapping device in individual, concise stages of a strapping process.

On the machine frame 11 one in its entirety with 10 designated strapping machine an essentially closed strapping guide channel 12, through and around a with package 13 indicated by dash-dotted lines around a strapping means 14, in particular a thermoplastic plastic strap, a strapping device 15 is supplied. Whose The task is to overlap ends a strapping surrounding the package with each other to connect, in particular by exposure to heat to weld together. For this are especially resistance heating or friction welding processes in use.

The strap 14 - e.g. also a Steel belt could be - will be outside the machine frame 11 on a rotatably mounted strapping roll (Drum) 55 in stock. First goes through the strapping means 14 on the machine input side a pair of rollers 16, which two on opposite one another Strapping surfaces frictionally has attacking roles that are tense towards each other and so with pressure against the strapping are held. The motor drive of this pair of rollers 16 promotes the strapping 14 in one Strapping agent store 17 of such a length of tensioning means 14 stored tension-free, such as he at least for the following strapping and for the Distance of the strapping material to the sealing unit 15 is required.

In the strapping feed direction onto the strapping stock 17 following is a second pair of rollers 18 arranged. Also the two roles of this Pair of rollers 18 drive the strapping 14 frictionally on. This pair of rollers is driven reversibly, because on the one hand it serves to fire the Strapping means 14 in the strap guide channel 12 and, with the opposite drive direction, on the other hand the withdrawal of the strapping means 14 and its tightening around the package 13. In the latter In the sense, the pair of rollers is a so-called "low tension clamping device".

In the strapping feed direction, the bullet and retraction roller pair 18 for the invention essential "high tension clamping device" by means of Subordinate tensioning drum 19, which with respect their structure and mode of operation based on the remaining figures is explained in detail.

A special one follows the tension drum 19 Strap clamp 20 and a guide channel 21, the strapping device 14 to the strapping device 15 feeds. Also details of this Aggregate 15 result from the following figures and their description.

The starting position of the machine for a strapping process schematically illustrates FIG. 2. The strapping means 14 was by means of the weft roller pair 18 (Direction of rotation according to the arrow in the upper right roll) through a strapping passage 22 of the tension drum 19 through through the strap guide 21 and around the in Fig. 2 and the following strapping guide channel, not shown 12 through the strapping device 15 fed until that leading strapping end 14 'against a so-called. Bullet switch 23 has run.

On its way there has free leading Strap end 14 'has a separator slot 24 in pass through a first strap clamp 25 and then a separator 26 within a so-called "Weld clamp" 27. The two separator slots serve to tighten the strapping ends in their common overlap area (initially) keep away from each other.

The above-mentioned components of the strapping device 15 are in the illustrated embodiment Part of a strapping device, which the strapping ends heated by means of friction welding and thereby plasticized, so that they can weld together. This is in the context of the present invention to be understood only as an example, because the invention is regardless of the specific type of design of the strapping device 15.

The actuation of the entry switch 23 by the leading, free end of strapping signals the machine control the machine starting position and practically performs a 'reset'. This starting position is characterized according to FIG. 2, that within the strapping channel 12 (Fig. 1) already a strapping section of the strapping means 14 is kept ready.

At the press of a button then initiated machine command the strapping process now sets itself after a package 13 is placed in the channel 12 is. The pair of rollers 18 receives the command to reserving drive (see arrow direction of the right top roller in Fig. 3) and pulls the strapping 14 back, which corresponds to the from Roller pair 18 exerted frictional forces around the Package 13 begins to tighten. Should the package 13 applied in a higher strapping tension as the "Low Tension" pair of rollers 18 can exercise the strapping means 14, switches the "High Tension" tensioning drum 19 in the strapping tensioning process on.

The strapping drum 19 comprises two arranged on a common rotatable carrier 28 Drum segments 29 and 30. The first drum segment 29 is rigid by means of two screw connections 31 attached to the head 28. The second drum segment 30, however, is only with the help of a single axis 32 held on the head piece 28 and at the same time about this axis 32 parallel to the axis of rotation 33 pivotally mounted on the head piece 28. Regarding the central axis 33 is the pivot axis 32 to the inlet side 34 of the strapping passage gap 23, the between the two drum segments 29 and 30 is kept clear, arranged offset.

The movable drum segment 30 has one Section 35, in which a particular as Coil spring trained compression spring 36 integrated which is at one end on the cut-out edge 37 and the other supported on an abutment 38 fixed to the head piece. This spring 36 holds the cut-out edge 35a of the movable drum segment against the back surface 38a of the abutment 38 fixed to the head piece, such that the strapping through channel 22 - as in FIG Fig. 3 shown - in this 'zero position' of the tension drum for the strapping means 14 freely is kept open. Contrary to the effect of the compression spring 36 is the drum segment 30 (with respect to the Figures) counterclockwise about axis 32 arranged pivotable.

Around the strapping means 14 with higher tensioning forces to tighten the package 13, the Tension drum 19 by a motor drive (in particular by means of a current-regulated, reversible low-voltage DC motor) in rotation offset, in the described configuration and arrangement of the movable drum segment 13 clockwise. The beginning of this rotation is shown in Fig. 4.

The rotation of the tension drum 19 has the consequence that around the outlet side edge 39 of the drum segment 30 guided strapping 14 on the Drum segment 30 exerts a force that it against the Force of the spring 36 counterclockwise around the Axis 32 pivoted. This narrows the strapping passage gap 22 on its strapping inlet side 34 and forms a strap clamp there 40 out with the towards each other directional arrows is indicated. Practical Experiments have shown that the strapping clamp 40 already after about 30 ° wrap angle, thus approximately the position shown in FIG. 4, reliably takes hold. From this position on, the take-away is of the strapping means 14 in the sense of its tightening around the package 13 no longer from Frictional forces dependent on a drum wrap come from.

As soon as the tensioning drum 19 straps 14 up to the previous one (e.g. by limiting the current consumption of the drive motor for the tension drum 19) tension value set, the with 41 designated second strapping clamp behind the separator 26 pressed against a counter-holder 42 and holds the strapping at 14 ". The drive the strapping clamp 41 takes place via a central camshaft 43, the control cam 44 for the second strapping clamp 41, 45 for a strapping knife 46, 47 for the first strap clamp 25 and 48 for an additional strapping clamp 20 has.

5 in the further course this additional strapping clamp 20, the tension drum 19 immediately is closed. Once this Strapping clamp 20 holds, is over the cam 45 a cutting knife 46 is activated and in the area 49 overlapping strapping ends of the strapping fastener trained - in the illustrated Embodiment by means of friction welding, which is why a vibration transducer 50 in a manner known per se due to friction between the tape ends in the overlap area 49 generates heat that causes them to fuse leads.

Meanwhile and while kept closed The strapping clamp 20 becomes the tension drum 19 already back to their starting position by motor 2 and 3 reversed, the pair of rollers 18 which is released when the tensioning drum 19 turns back Strapping excess length due to reversed Direction of rotation in the strapping material store 17 (Fig. 1) promotes. Now the strapping clamp 20 open again. This is shown in FIG. 6 the rest of the package strapping that has now been completed 50 is recognizable.

The working cycle of a strapping is then completed in that after removing the with complete strapping 51 and a strapping closure 52 provided completed package 13 the strapping tool from the work table of the machine 10 14 again in the strapping channel 12 is shot, with which the basic position the machine according to FIG. 2 is reached again is.

Deviating from the illustrated embodiment can as a helical compression spring 36 in the embodiment shown spring also by another clamping means to be replaced. For example, a coiled leg spring on the swivel axis 32 rest with one end on head 28 and with their other end of the turn on the pivoting Drum segment 30 is fixed.

The one shown in Figs. 4 and 5, relative low wrap angle of the two peripheral surfaces 29 'and 30' of the drum segments 29 and 30 understands is also only an example. He is dependent from the length of strapping that is conveyed must be to the required strapping tension to achieve on package 13. With more compressible Packages are this strapping length naturally larger than with less compliant Packages 13.

The inventive design of the tension drum 19 also allows them to be brought up a clamping force rotated circumferentially by more than 180 ° becomes. Because of the strapping of the strapping the strapping clamp 40 opened again and the high traction of the wrap friction taken over. It follows the advantage that the spring 36 is dimensioned very weak can be. This in turn has the advantage that the spring 36 responds particularly quickly to Closing the strapping clamp 40 already a very small wrap angle of the movable Segment 30 is sufficient.

In the context of the invention it is essential that after only a slight circumferential rotation of the tension drum 19 this one defined on the strapping means 14 Tractive force can apply what the invention with the help of the strapping means 14 itself controlled strapping clamp 40 takes place.

Claims (10)

1. Apparatus for hooping packages with a hooping means (14), in particular a thermoplastic band, which is introduced from a hooping means supply into a hooping means guide channel (12) surrounding the package and fed through this channel to a hooping means fastening unit (15) and wherein means for tightening the hooping means round the package are provided, including a rotatable tensioning drum (19) which has a diametrical gap (22) for passage of the hooping means and two drum segments (29, 30) which are spaced apart by the gap for passage of the hooping means and on whose circumferential surfaces the hooping means can be wound for tensioning, characterised in that the first drum segment (29) is rigid and the second drum segment (30) is movable relative to the first drum segment (29), narrowing the gap, and at the end of its movement together with the first drum segment (29) forms a hooping means clamp (40).
2. Apparatus according to claim 1, characterised in that the movable drum segment (30) is movable into the clamping position solely on account of the tensile force of the encompassing hooping means (14).
3. Apparatus according to claim 1 or 2, characterised in that the movable drum segment (30) is movable out of its position defining the gap (22) for passage of the hooping means, against a spring force into the clamping position.
4. Apparatus according to any of claims 1 to 3, characterised in that the movable drum segment (30) is movable about a pivot pin (32) running parallel to the axis of rotation (33) of the tensioning drum (19).
5. Apparatus according to claim 4, characterised in that the pivot pin (32) is offset towards the hooping means clamp (40).
6. Apparatus according to any of the preceding claims, characterised in that the drum segments (29, 30) are fixed or coupled to a common rotationally driven support (28).
7. Apparatus according to any of the preceding claims 3-6, characterised in that the spring force results from a spring (36) supported on the support (28) and the movable drum segment (30).
8. Apparatus according to claim 7, characterised in that the spring (36) is a compression spring essentially arranged in a recess (35) of the movable drum segment (30).
9. Apparatus according to any of the preceding claims, characterised in that between the tensioning drum (19) and the hooping means fastening unit (15) is arranged a controlled hooping means clamp (20) which holds the tightened hooping means (14) fast after tensioning by the tensioning drum (19), while the hooping means fastening unit (15) forms the hooping means fastening (52) and reverses the tensioning drum (19) into the starting position.
10. Apparatus according to claim 9, characterised in that the tensioning drum (19) can be rotated by motor back into its starting position.

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