Device for strapping

Abstract

The invention is related to a strapping device (1) for the strapping of an object (14) with a strapping tape (5). The strapping device (1) comprises a means of guidance (3) for guiding a strapping tape (5), which serves for the purpose of forming a loop of strapping tape (5) in a waiting position. The formation of the loop takes place independently of the position of the object to be strapped (14). The strapping device (1) furthermore comprises a means for movement of the loop (4). This means serves for positioning the loop of strapping tape (5) formed by the means of guidance (3) from the waiting position into a stacking position around an object (14) to be strapped, after this object has been positioned on a work surface (2).

Description

[0001] The invention is related to a device for the strapping with a strapping tape of an essentially cube-shaped (cuboid) object, for example, of a stack of printed products or suchlike.

[0002] Known from prior art are various devices, which serve for the strapping of stacks of printed products by means of strapping, in particular of a strapping tape. In the case of these devices, a stack of printed products to be strapped is brought to a strapping device by a feeding device, where one or several strapping tapes are laid around the stack. After the strapping, the strapped stack is conducted away from the work zone. Utilised as strapping tapes are mostly plastic tapes, e.g., made of polyethyleneterephthalate or polypropylene.

[0003] Strapping means are primarily laid around a stack, resp., around a cube-shaped (cuboid) device in two directions: In the direction of conveyance (longitudinal strapping), in which the stack brought into the work zone, and transverse to it (transverse strapping). While the strapping in transverse direction can be coped with by the devices known from prior art, a strapping in longitudinal direction with the same devices is in most cases associated with certain problems, because as a result of the principle involved parts of the machine are arranged in a manner, which makes them liable to interfere with the process.

[0004] From DE 41 00 276 a device is known, which comprises a curved, longitudinally slotted channel, which is arranged at an angle above and adjacent to a stack of printed products to be strapped. A strapping tape is introduced into the channel, in order to thereupon be laterally pulled out of it. Until the tape finally has been laid around a stack to be strapped, it first has to slide over an inclined surface and then has to overcome at an angle a free stretch in the air. This arrangement encompasses certain uncertainties, because as a result of the inclined trajectory it is only poorly possible to determine, where the tape will come to lie.

[0005] From DE 42 30 730 a further device is known, which comprises a static and a movable tape guide channel. This channel is arranged at an oblique angle to a feeding device. In order to be in a position to rationally strap a stack of printed products, it is necessary to align it at a corresponding angle relative to the channel.

[0006] From EP 0 725 005 a device is known, in the case of which a strapping tape is conveyed across a free stretch of air by means of air pressure. This device has the disadvantage, that a secure conveyance of the strapping tape across the free stretch of air is only able to be guaranteed with difficulty. Apart from this, as a result of the principle it is only possible to form the tape into a loop after a stack to be strapped has reached a work zone.

[0007] It is the objective of the invention presented here to demonstrate a strapping device, which avoids the disadvantages known from prior art. The device is to make it possible to rapidly strap objects in longitudinal—and/or in transverse direction in a simple manner.

[0008] The objective is achieved with the invention defined in the claims.

[0009] The invention divulged here is in preference suitable for the strapping of printed products and other objects. These can have differing dimensions and positions. The invention is in particular distinguished by a rapid processing and a high flexibility, because the loop can be prepared independent of the position of the stack to be strapped. Because of only a small number of fast moving parts, an optimised cycle is achieved. The invention is suitable in particular for a strapping both in longitudinal as well as in transverse direction.

[0010] The invention is based on the fact, that a means of strapping, in particular a strapping tape, which is to be laid around a stack of printed products, is prepared by means of a suitable loop forming device in a waiting position, independent of and free of (uninfluenced by 90°) the momentary position of the stack to be strapped, i.e., is formed into a loop. This prepared loop thereupon, as soon as the stack to be strapped has reached a strapping position, by means of a loop movement device by turning (e.g., folding over by) and/or by lateral displacement is brought into a stacking position from the waiting position, in which it encircles the stack at a certain distance in preference centrally. Subsequently the loop, starting out from the stacking position, is laid around the stack, tightened and locked so as to form a strapping.

[0011] The invention can be designed in such a manner, e.g., that the loop forming device is a groove embedded in a horizontal work surface, which serves as guide track, resp., guide means for the strapping device. Into this groove the means of strapping is introduced, resp., inserted in longitudinal direction and formed into a loop (loop in waiting position). In doing so, the groove is designed in such a manner, that the loop does not protrude from the groove and so does not have an obstructive effect. As soon as the stack to be strapped has reached a strapping position, the loop present in the groove in the waiting position is raised away from the work surface into an upright position by means of the loop forming device (e.g., by rotation around a point) in such a manner, that the loop comes to lie above and lateral to the stack to be strapped. The loop is now in the stacking position.

[0012] The loop movement device, for example, comprises one or several straight or curved arms arranged as fixed or movable, along which grippers are located, which can be displaced under control. The grippers are designed in such a manner, that they are in a position to bring the means of strapping (strapping tape) from the waiting position into the stacking position. For example, the grippers, depending on the field of application, can have an open or closed, single- or multi-part construction. In preference they are of lightweight construction, so that they can be displaced rapidly.

[0013] Particularly suitable as drive for the loop movement means, resp., for the grippers, are recirculating traction elements, air pressure (compressed air), hydraulic systems, solenoid or piezo-electric drives. The one or more loop movement means advantageously are designed in such a manner, that the movement of the grippers along the arms and the position of the arms, resp., their relative course, is adjustable. As a result of this, objects of the most differing size (height, width, length and shape) are able to be processed. Because of the flexible design, it is possible to influence the loop even while it is brought from the waiting position to the stacking position, in that, for example, the arms are moved relative to one another. This has the effect of specifically enlarging the loop or of making it smaller. The stack can assume differing strapping positions.

[0014] In the stacking position, the loop is bigger than the circumference of the stack to be strapped, in such a manner, that it encircles the latter at a certain distance. Starting out from the stacking position, the loop is separated from the loop movement device, resp., from the one or more grippers and drawn together in such a manner, that the strapping means tightly girdles the stack to be strapped. Subsequently the means of strapping is tied down and closed to form a strapping.

[0015] A preferred embodiment of the invention is explained in more detail on the basis of the following Figures.

[0016] These illustrate:

[0017] FIG. 1 a preferred embodiment of a device in accordance with the invention with a loop of a strapping tape;

[0018] FIG. 2 the device according to FIG. 1 with a stack to be strapped;

[0019] FIG. 3 the device in accordance with FIG. 1 with a strapped stack.

[0020] FIG. 1 schematically and in a strongly simplified way illustrates a strapping device 1 in accordance with the invention. This, i.a., comprises a work surface 2, a groove 3 embedded in the work surface and two loop movement devices 4. The groove 3 embedded in the work surface 2 runs essentially along the edges of a rectangle and serves as means of guidance (guide channel) for guiding a strapping means, resp., the strapping tape 5. The groove 3 is designed in such a manner, that the strapping tape 5 can be introduced into it, in that it is pushed into it in the direction of the arrow P either actively or passively from a supply magazine, for example, from a supply roll, which is located underneath the work surface 2. If so required, additional tape feeding means (not depicted in more detail), for example, in the form of tape feed rolls (not depicted in more detail) are present, which assist in the introduction of the strapping tape 5 into the groove 3. The depth of the groove 3 is selected in such a manner, that a strapping tape 5 introduced into it does not protrude from the groove 3. Additional elastic elements (not illustrated in more detail), such as lamella or bristles, close off the groove 3 against the work surface 2 in such a manner, that the strapping tape 5 is secured against inadvertently coming out of the groove 3 and that the danger of contamination with dirt of the groove 3 is reduced. The groove 3 can also be closed-off during the introduction of the strapping tape 5 by means of a rigid element (not illustrated in more detail).

[0021] Also located underneath the work surface 2 are as such known tightening—and cutting devices (not depicted in more detail) serving for tightening the strapping tape 5. A closing device 10 serves to tightly close the strapping tape 5 to form a ring, which tightly encircles the stack of printed products (refer to FIG. 2). The closing device, for example is an ultrasonic welding device, which is located in the zone of the work surface 2. It goes without saying, that also other devices can be utilised for closing and cutting off the strapping tape 5.

[0022] In the illustrated embodiment, the two loop movement means 4 each respectively comprise one arm 11, which protrudes from the work surface 2 in the zone of the groove. The curved arms 11 essentially run parallel to—and extend over the work surface in an arc in such a manner, that a stack to be strapped (refer to FIG. 2) can be moved under them or across between them. Along each one of the arms 11, a gripper 12 is arranged to be displaceable under control in a guide groove 13. The grippers 12 in the illustrated waiting position project into the groove 3 and are designed in such a manner, that they temporarily take hold of the strapping tape 5 as soon as it has been introduced into the groove 3 to form a loop, and thereupon are able to raise it away from the work surface into an upright position.

[0023] The arms 11 can either be arranged to be movable or else can have a variable geometry in such a manner, that their position relative to the work surface 2, their lateral distance and course can be changed, resp., adapted. As a result of this, it is possible to strap stacks of the most differing sizes at different stacking positions. The stacks to be strapped can be supplied, resp., conveyed away again between the arms or transverse to them. Through the curvature and the course of the arms II, the loop can be influenced in a specific manner while it is being brought into the strapping position.

[0024] In the illustrated embodiment, the grippers 12 each respectively consist of a plastic element (e.g., an elastic clip) with an essentially U-shaped opening, which serves for the temporary taking hold of the strapping means 5. These plastic elements are each respectively driven by a steel string guided within the guide groove 13 (not illustrated in more detail). Underneath the work surface there is a driving device (not depicted in more detail), which serves to unroll -and roll up the steel strings of each arm 11. The arrangement illustrated is characterised, i.a., by the fact, that the mass of the moving parts (gripper 12 and steel string, resp., loop of strapping tape) is very low and that only few parts have to be moved rapidly. The grippers 12 serve as driving devices for the means of strapping 5. Depending of the field of application, instead of the U-shaped opening depicted here, they can also comprise an opening with an O-shaped, slotted cross section, from which the means of strapping 5 can be pulled out laterally. Other designs are also feasible.

[0025] FIG. 2 in a strongly simplified and schematic manner illustrates the device in accordance with the invention 1 according to FIG. 1 with a stack to be strapped 14 on the work surface 2. This stack is depicted simplified as a cube-shaped object. The strapping tape 5 in the waiting position previously formed into a loop in the work surface 2 is located in a position raised upright by approx. 90° relative to the work surface 2 (stacking position), lateral to and above the stack 14 and at a certain distance from it. The loop of strapping tape has been raised into an upright position by the grippers, in that these have been moved along the arms 11. Starting out from this raised upright position (stacking position), the strapping tape 5 is pulled together in the direction of the arrows 15, in that it is pulled backwards into the supply magazine located underneath the work surface 2 (not illustrated in more detail). In doing so, the strapping tape 5 is separated from the grippers 12. As a result of being pulled together, the tape 5 comes to lie tightly around the stack to be strapped 14 (refer to FIG. 3). The grippers 13 are positioned in dependence of the stacking position of the stack 14.

[0026] The grippers 12 can be moved either in synchronicity or asynchronously. As a result of this, it is possible, e.g., to at least in part bring the loop into an upright position already while the stack 14 to be strapped is still in the course of being supplied.

[0027] FIG. 3 illustrates the device in accordance with the FIGS. 1 and 2 with a strapped stack 14. The strapping tape 5 has been cut off from the remaining tape and closed to form a ring by means of the closing device 10. The grippers 12 are being moved back to their starting positions in the zone of the work surface 2 in the direction of the arrows 16. After the stack 14 has been conveyed away, the device is in readiness for the strapping of a further stack of printed products. While the new stack (not depicted in more detail) is being supplied, in the loop guidance means the loop is already being prepared for its strapping.

[0028] For the sake of simplicity, the strapping of a stack has only been described in one direction. The invention, however, can also be designed in such a manner, that more than one strapping, e.g., in two directions are possible, inasmuch as correspondingly more loop movement means 4 are provided. In the zone of the work surface 2, for example, a rotary table can be arranged, which makes possible an additional different alignment of the stack to be strapped.

[0029] For the specialist it is a matter of course, that the invention is not solely limited to the embodiment illustrated.

Claims

1. Strapping device (1) for the strapping of an object (14) with a means of strapping (5), characterised in that the strapping device (1) comprises a means of guidance (3) for guiding the strapping means (5), which means of guidance (3) serves for the formation of a loop of means of strapping (5) in a waiting position, independent of the position of the object to be strapped (14), and that a loop movement means (4) is present, which serves to position the loop of strapping means (5) formed by the means of guidance (3) from the waiting position in a stacking position around an object to be strapped (14).

2. Strapping device (1) in accordance with claim 1, characterised in that the means of guidance (3) is a groove (3) embedded in a work surface (2), in which the means of strapping (5) is able to be pushed in, and that the loop movement device (4) comprises at least one arm (1) projecting from the work surface (2) with at least one gripper (12), which is arranged to be displaceable under control along the at least one arm (11) and which serves as driving means for moving the loop of strapping means (5) from the waiting position into the stacking position.

3. Strapping device (1) according to claim 2, characterised in that the at least one arm (11) is curved.

4. Strapping device (1) in accordance with claim 2 or 3, characterised in that the at least one arm (11) is arranged to be movable relative to the work surface (2).

5. Strapping device (1) according to one of the claims 2 to 4, characterised in that the at least one gripper (12) comprises an opening with a substantially U-shaped or O-shaped, laterally slotted cross section, which serves for the temporary taking hold of and moving of the means of strapping (5) and which is designed in such a manner, that it can release the means of strapping (5) in a stacking position.

6. Strapping device (1) in accordance with one of the claims 2 to 5, characterised in that in the interior of the arm (11) a movable, driven wire string is arranged, which is connected with the at least one gripper (12) and which serves for driving it.

7. Strapping device (1) according to one of the claims 2 to 6, characterised in that the strapping device (1) comprises at least one electric motor and/or one compressed air motor and/or one hydraulic motor and/or one solenoid motor and/or one piezo-electric motor, which serves or which serve for driving the at least one gripper (12).

8. Strapping device (1) in accordance with one of the claims 2 to 7, characterised in that the strapping device (1) comprises precisely two arms (11) each respectively with one gripper arranged to be controllably movable along it.

9. Strapping device (1) according to one of the claims 2 to 8, characterised in that the means of guidance (3) extends essentially along the edges of a rectangle.

10. Strapping device (1) in accordance with one of the claims 2 to 9, characterised in that the groove (3) is closed off by means of elastic elements.