Forming Device

BACKGROUND AND FIELD

The invention relates to a forming device for creating a tube from a material web for form, fill and seal machines. In particular, the invention relates to those kinds of forming devices which are designed to form tubular cross sections, the boundary lines of which exhibit locally large changes in their curvature. This refers to boundary lines of a tubular cross section which, as in the case of a rectangular cross section, for example, comprise multiple comparatively long, linear portions (the sides of the rectangle), which extend in different directions and are connected to one another by comparatively short, curved portions (the rounded corners of the rectangle).

A huge variety of generic forming devices for creating a tube from a material web are known in the art. These forming devices are used in packing machines, which are also referred to as tubular bag machines or form, fill and seal machines, for reforming a planar, flexible material web into a tube. Depending on the running direction of the material web during reforming, a distinction is made between vertical and horizontal tubular bag machines.

Vertical tubular bag machines are preferably used for packing bulk material into tubular bags, whereas horizontal tubular bag machines are particularly used in the packing of piece goods. The reforming of the material web from the planar into the tubular state is completed within the tubular bag machine on a forming device.

Some forming devices have a shoulder part with a shoulder surface on which the planar cross section of the material web is curved to begin with, and a prism part with a prism surface on which the curved cross section is reformed into a closed tubular cross section. The shoulder surface and the prism surface are connected to one another along a spatial reforming edge. The forming device may be a one-part or multi-part spatial forming body made of solid, inflexible material which is produced either from solid material or from sheet metal, usually steel or another material. Adjustable forming devices which are designed for the production of different tubular cross sections may comprise multiple forming elements, which each have only one portion of shoulder surface, reforming edge and prism surface, wherein linear reforming edge portions, in particular, i.e. regions in which the boundary line of the tubular cross section being produced is linear, are not even physically realized.

The packing material web is removed from a roll as a flat web and reformed into a tube by means of the forming device. The tube may enclose a round, rectangular, or other convexly formed cross section. The geometry of the guiding surface of the forming shoulder, in other words the surface that comes into contact with the packing material web, should, where possible, be of such a size and spatial configuration that every material fiber of the packing material web covers the same path during reforming and the space between adjacent material fibers transversely to the running direction remains constant, so that the packing material web is neither stretched nor lengthened nor permanently deformed.

Particularly in the case of vertical forming devices for the production of tubular bags, the tubular cross section located in the prism part is frequently gravity-filled with packing material (frequently bulk material) through a prismatic filler tube which projects in a vertical direction into the prism part of the forming device. In the case of horizontal forming devices for the production of tubular bags, a prismatic filler tube which projects in a horizontal direction into the prism part of the forming device is sometimes used in a comparable manner, in order to keep the part of the created tubular cross section located in the prism part open, while the packing material (frequently piece goods) is pushed into said cross section. In order for the holding-open of the tubular cross section to be reliably achieved, the filler tube projects very far into the prism part in these cases, for example 100 mm, 200 mm, or more. Both in the case of vertical and also horizontal forming devices, the filler tube is customarily of such a size that it is at a sufficient distance, for example 10 to 20 times the thickness of the material web, or more, from the prism surface and from the reforming edge of the forming device, so that the reforming and transportation of the material web is not impeded or influenced in some other way. It follows from this that the reforming of the material web into a tubular cross section is only caused by the reforming edge and the filler tube itself is not involved in this tube formation.

Particularly in the field of horizontal tubular bag forming devices, significant improvements have been able to be achieved in the recent past, which have led, among other things, to the forming devices being adjustable and therefore universally useable, configured in a manner suitable for cleaning, and, on account of an integrated data-processing device, being capable of adapting to a wide variety of applications, as a result of which it is possible for the highest qualities to be achieved.

WO 2019/123356 A1 describes a forming device for horizontal tubular bag machines for creating a tube from a material web which can easily be modified for the production of different bag cross sections. The forming device comprises a horizontal base plate which has a slot running in a transport direction, and also two shoulder parts fastened to the base plate on either side of the slot, which shoulder parts each exhibit a portion of a reforming edge via which the material web is conducted for reforming, wherein the shoulder parts each comprise at least two shoulder part segments detachably connected to one another, in which their distance from one another can be set through the insertion of one or multiple lengthening elements.

So that tubular cross sections with a different width and different depth can be produced easily and cost-effectively, WO 2020/058531 A1 describes a forming device for creating a tube from a material web, having a first forming region in which the material web is guided from a straight web run-in to a reforming edge and is thereby reformed from a planar into a curved state, a second reforming region attached to the first reforming region downstream, in which the material web is guided from the reforming edge to a web run-out cross section, and in this case is reformed from the curved into a tubular state, which comprises the following: a base frame, two forming elements mounted movably on the base frame alongside one another, transversely to the transport direction of the material web, each having a reforming edge segment. The forming elements each comprise a first partial element and a second partial element, wherein the second partial element strikes the first partial element in a minimal setting, and the second partial element is adjustable up to a maximum position in the direction of the reforming edge segment, creating a hole in the reforming edge which grows with the distance from the first partial element.

Material webs made of a wide variety of materials are used to produce tubular bags for packing purposes, depending on the intended use. So, for example, pure plastic films are used which may have a one-ply or multi-ply design. Plastic films may, in addition, have a metallic coating, for example aluminum. Composite materials may be based on paper as the carrier material, for example, and likewise coated with metal and/or with plastic in addition. Paper-based packing materials, in particular, are currently experiencing a renaissance as a result of the current trend towards sustainability and environmental protection.

All these different packing materials exhibit different behavior when they are reformed from a planar material web into a closed tubular cross section. Hence, the tube forming device and the packing machine in which the tube forming device is installed have to be adapted to the currently used packing material in terms of the run-in angle of the material web into the tube forming device, in terms of the web tension, and possibly in terms of the web running speed, in such a way that the most crease-resistant forming possible is guaranteed and there is no folding or even tearing of the material web. It has been demonstrated that many paper-based packing materials are particularly difficult to process when the tubular cross section exhibits portions with a sharp curvature.

Based on this prior art, a problem addressed by the present invention is that of developing known forming devices for the creation of a tube from a material web, in particular horizontal forming devices of this kind for packing piece goods, in such a manner that they allow the production of tubular cross sections with a greatly varying curvature of the boundary line of the tubular cross section in a simple and cost-effective way.

These problems are solved by a forming device having the features of patent claim 1. Advantageous embodiments and developments are described in the dependent patent claims.

The proposed reforming device may be designed in accordance with one or several of the aspects described above. For clarification, these aspects are described with reference to the drawing figures, in which several of these aspects are realized. Each of these aspects is claimed both separately and also in any combination.

SUMMARY

In order to solve the problem, a forming device for reforming a material web into a tube is proposed, which comprises a shoulder part with a shoulder surface on which the planar cross section of the material web is initially curved, and a prism part with a prism surface on which the curved cross section is reformed into a closed tubular cross section, wherein the shoulder surface and the prism surface are connected to one another along a spatial reforming edge which has at least one reforming edge portion with a slight curvature and at least one reforming edge portion with a strong curvature, wherein in the prism part, at least in the region of a reforming edge portion with a strong curvature, an inner former element with an inner former surface facing the reforming edge and the prism surface is arranged in such a manner that between the prism surface and the inner former surface, a gap which runs along the reforming edge is formed, the width of said gap being adjustable.

The gap width in this case represents the perpendicular distance of the inner former surface from the prism surface and therefore from the reforming edge. The gap is therefore sufficiently large for the material web to be allowed to pass through without becoming trapped or otherwise hindered in its movement. The inner former element in this case helps guarantee a precise and crease-free reforming, in that the packing material is helped by the action of the inner former surface in this case to fit snugly in the reforming edge region with a strong curvature.

In one embodiment of the proposed forming device, it is provided that the inner former element is movably arranged relative to the reforming edge, so that the gap width between two characteristic positions which represent a maximum gap width (e.g. as the maintenance position for removing a jam or for introducing a new material web) and a minimal gap width (e.g. as the working position for the thinnest material web that can be processed using the forming device) is adjustable.

In an advantageous development, the proposed forming device is configured in such a manner that the inner former element can be fixed between the two characteristic positions referred to above in at least one intermediate position, for example in one of multiple intermediate positions. The inner former element in this case may either be fixed in any intermediate position or the forming device is configured in such a manner that it has multiple discrete intermediate positions, for example in that screening is provided which defines the intermediate positions in which the inner former element can be fixed.

The movement in this case can take place in a different way. For example, the inner former element can be moved perpendicularly to a longitudinal extent of the prism part, i.e. directly towards the prism surface or away from the prism surface. This means that in order to increase the gap width, the inner former element is moved into the channel formed by the prism surface, said channel being needed for the introduction of the piece goods into the tubular cross section formed. According to a development, it may be provided that the inner former element is movable in this direction and at the same time is flexibly mounted, for example against the force of a return spring. It is thereby achieved that the setting of the gap width takes place as needed and automatically, as it were, in that the material web displaces the inner former element to the center of the tubular cross section when the forming forces become so great that, despite help from the inner former element, the material web is no longer able to fit snugly in a reforming edge region with a strong curvature, for example because the thickness of the material web fluctuates and a point with a greater thickness passes the reforming edge. Once this thicker point of the material has passed the gap, the inner former element is moved back by the flexible bearing, for example a return spring, into its original position.

Under certain circumstances, an embodiment of this kind in which the inner former element is movable perpendicularly to a longitudinal extent of the prism part may be unfavorable, specifically if the movement direction of the inner former element means that the introduction of piece goods into the tubular cross section is impeded. For this reason, according to another embodiment of the proposed device, it is proposed that the inner former surface forms an acute angle with the prism surface relative to a longitudinal axis of the prism surface, and the inner former element is movable in the direction of the longitudinal axis. In this embodiment, the inner former element may be moved back and forth, in order to increasing or reducing the size of the gap between the inner former surface and the reforming edge in the transport direction of the packing material, and therefore parallel to a longitudinal axis of the prism part.

In a particularly advantageous embodiment it is provided that the inner former element, in addition to the movement of the packing pieces in the transport direction, which brings about an adjustment of the gap width of the gap formed between the inner former surface and the reforming edge, in a similar way to that described above, is flexibly mounted perpendicularly thereto, for example against the force of a return spring, in order to allow a temporary adjustment of the gap width in the event of fluctuating reforming forces, for example due to fluctuating material thickness of the material web.

In an advantageous embodiment of the proposed forming device, it is provided that each inner former element is operatively connected to an actuator, in order to generate movement relative to the reforming edge. In this way, it is possible for the movement of the inner former element to be automated, so that manual interventions are avoided. Actuators of this kind may be designed as an electromotive spindle drive, pneumatic cylinder, or the like, for example, and are particularly advantageously actuated by a machine controller of a packing machine.

Furthermore, in the case of the proposed forming device, it may be provided that the reforming edge has at least two reforming edge portions with a strong curvature, wherein an inner former element has an inner former surface extending over the at least two reforming edge portions. An example of this is a forming device which is designed to produce a rectangular tubular cross section, wherein the run-in material web faces a straight reforming edge portion, at each of the two ends of which a reforming edge portion with a strong curvature is located. An inner former element in the aforementioned sense may have an inner former surface, for example, which extends both over the straight reforming edge portion and over the two adjacent reforming edge portions with a strong curvature, so that the material web in this entire region is guided and supported between the inner former surface and reforming edge.

Alternatively or in addition, it may be provided in the case of the proposed forming device that it comprises at least two forming elements which are movable relative to one another for adjusting the tubular cross section being produced, said forming elements each having a reforming edge portion with a strong curvature, wherein in the region of the reforming edge portion with a strong curvature of each forming element, an inner former element which is movement-coupled with the forming element is arranged.

Two things are achieved by this embodiment. On the one hand, the associated inner former element is synchronously carried along with each forming element when the forming device is adjusted for production of another tubular cross section. On the other hand, the inner former element remains movable relative to the forming element, in order to adjust the gap width, so to increase the gap to the maximum possible extent, for example, when a new material web has to be introduced or the gap width adapted to a thicker or thinner material of the packing material web.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention is explained in greater detail below with the help of exemplary embodiments and associated drawing figures. In the drawings

FIG. 1 shows a forming device according to the invention with inner former elements by comparison with a state-of-the-art forming device with a filler tube;

FIG. 2 shows a forming device of the proposed kind according to a first exemplary embodiment in a perspective view;

FIG. 3 shows a side view of the forming device according to FIG. 2 with the inner former elements in two characteristic positions;

FIG. 4 shows the characteristic positions of the inner former elements of the forming device from FIGS. 2 and 3 as a perspective view;

FIG. 5 shows geometric relations in a first characteristic position (working position),

FIG. 6 shows geometric relations in a second characteristic position (maintenance position),

FIG. 7 shows a forming device of the proposed kind according to a second exemplary embodiment as a perspective view;

FIG. 8 shows a perspective detail view of the forming device according to FIG. 5;

FIG. 9 shows the characteristic positions of the inner former elements of the forming device from FIGS. 5 and 6 as a perspective view;

FIG. 10 shows examples of possible embodiments of the inner former elements.

DETAILED DESCRIPTION

FIG. 1 represents in the upper drawing FIG. 1A a forming element 12 of a forming device 1 according to the invention with an inner former element 5. For comparison, the lower drawing FIG. 1B shows a forming element 12 of a state-of-the-art forming device 1 known per se with a filler tube 8 which projects horizontally by the amount F into the prism part of the forming device 1, so that the tubular cross section is kept open while the tube is filled with the packing material, i.e. in order to prevent the tubular cross section from collapsing. A direct comparison between the drawing FIGS. 1A and 1B with one another shows that the inner former element 5 does not project into the tubular cross section, but only has a direct geometric operative relationship with the reforming edge 4 of the forming element 12, in that a comparatively narrow gap remains between the inner former element 5 and the reforming edge 4, the gap width of which is only approx. two to three times the thickness of the material web in the exemplary embodiment, as a result of which the reforming of the material web into a closed cross section by the reforming edge 4 and the inner former element 5 is carried out jointly. According to the arrangement of the inner former element 5 relative to the forming element 12, this effect is found, in particular, in the reforming edge portion with a strong curvature 42, in which the inner former surface 51 of the inner former element 5 is arranged relative to the reforming edge 4.

The forming device is configured in such a manner that it is designed for producing a rectangular tubular cross section. The reforming edge 4 therefore has reforming edge portions with a slight curvature 41 and reforming edge portions with a strong curvature 42. The inner former elements 5 in this case are arranged in such a manner, and their inner former surfaces 51 are formed in such a manner, that they follow the contour of the reforming edge 4 in the region of the corners of the tubular cross section, and therefore in reforming edge portions with a strong curvature 42, so that they act jointly with the reforming edge 4 to reform the material web guided through between them. The inner former elements 5 are movably arranged relative to the reforming edge 4 in such a manner that the gap width between the inner former surface 51 and the reforming edge 4 is adjustable. This is achieved in that the inner former surface 51 forms an acute angle α with the prism surface of the forming device relative to a longitudinal axis of the prism surface, i.e. the transport direction of the packing material, and the inner former element 5 is movable in the direction of this longitudinal axis. Through this configuration, the adjusting range ΔA of the inner former element 5 in the transport direction of the packing material is always greater than the change ΔG in the gap width between the inner former surface 5 and the reforming edge 4 which it causes:

ΔA=ΔG/sin α

FIGS. 2 to 6 show in different representations an overall view of a first exemplary embodiment of a forming device 1 of the proposed kind as a perspective view, the forming device with two characteristic positions of the inner former elements in side view and in perspective view, and the geometric relations on the forming device in both characteristic positions. Two forming elements 12, which are formed in such a manner that a material web guided over them is reformed into a tubular cross section, are arranged on a base plate 11. Lying on the base plate 11, items which are to be packed can be pushed into the formed tubular cross section. Before the start of the reforming region, front guide elements are therefore arranged on the base plate 11, which guide elements limit the transport path of the items being packed. Rear guide elements 13 are arranged on the base plate 11 behind the two forming elements 12, said guide elements guiding the finally packed items along the transport path. Viewed in the transport direction, two inner former elements 5 are arranged between the front guide elements 13 and the two forming elements 12, each an inner former element having an inner former surface 51 facing the reforming edge 4. Each of the two inner former elements 5 is mounted so as to be movable in the transport direction of the items being packed in a longitudinal hole in the base plate 11 and can be fixed in a desired position by means of a screw. In order to introduce a material web into the forming device, the inner former elements 5 can be moved manually into a characteristic position in which the gap width has a maximum dimension between the inner former surface 51 and the reforming edge 4 in each case. If this is achieved, the inner former elements 5 can likewise be moved into a second characteristic position manually and fixed, in which position the inner former surface 51 comes into a spatial relationship and operative connection with the reforming edge 4, which guides and conducts the material web, in particular in reforming edge regions with a strong curvature 42, and in this way contributes directly to the reforming of the material web into a tubular cross section.

FIGS. 5 and 6 show in various views the geometric relations at the proposed forming device. In FIG. 5 the inner former element 5 is located in a characteristic position, which is a working position. The adjusting range A1 of the inner former element 5 is maximal here, relative to the guide element 13. The gap width G1 in this position is minimal, so that the contribution of the inner former element 5 to the reforming of the material web into a tubular cross section is maximal. The inner former element 5 is in a characteristic position in FIG. 6 which is a maintenance position. The adjusting range A2 of the inner former element 5 is minimal here, relative to the guide element 13. The gap width G2 is maximal in this position, meaning that the contribution of the inner former element 5 to the reforming of the material web into a tubular cross section is minimal, unless this gap width has been chosen because a thicker material web is being processed, which requires a correspondingly greater gap width.

FIGS. 7 to 9 show in different representations an overall view of a second exemplary embodiment of a forming device 1 of the proposed kind as a perspective view, a perspective detail view of the forming device, and the characteristic positions of the inner former elements of the forming device as a perspective view. Two forming elements 12 which are formed in such a manner that a material web 7 guided over them is reformed into a tubular cross section are arranged on a base plate 11. Lying on the base plate 11, items which are to be packed can be pushed into the formed tubular cross section. Before the start of the reforming region, front guide elements 13 are therefore arranged on the base plate 11, which guide plates limit the transport path of the items being packed. Rear guide elements 13 are arranged on the base plate 11 behind the two forming elements 12, said guide elements guiding the finally packed items along the transport path. Viewed in the transport direction, two inner former elements 5 are arranged on the base plate 11 between the front guide elements 13 and the two forming elements 12, each inner former element having an inner former surface 51 facing the reforming edge 4. Each of the two inner former elements 5 is mounted so as to be movable in the transport direction of the items being packed in an elongate hole in the base plate 11. Two actuators 6 are arranged on the underside of the base plate 11 which are each operatively connected to one of the two inner former elements 5 in such a manner that the inner former elements 5 can be moved towards, or away from, the reforming edge, and can be thereby be fixed in a desired position. It is therefore possible for each inner former element 5 to move to and fix the desired characteristic position without manual intervention, for example determined by a machine controller.

FIG. 10 shows four examples of possible embodiments of the inner former elements 5, and also of the shape and arrangement of the inner former surfaces 51 thereof relative to the forming elements 12 and the reforming edge 4. The upper representation 10A shows in side view the viewing direction C and a plane of intersection D, which has been applied to the lower representations 10B to 10E, in order to explain possible configurations of inner former elements 5. Depicted schematically therein are the base plate 11 and the two forming elements 12, which are jointly configured to produce a rectangular tubular cross section, which are composed of reforming edge portions with a slight curvature 41 and reforming edge portions with a strong curvature 42. The embodiment according to the representation 10B corresponds to the form and arrangement of the inner former elements 5 of the exemplary embodiments already explained in FIGS. 2 to 6 and 7 to 9, in which two inner former elements 5 each extend along a reforming edge portion with a strong curvature 42 in the upper half of the tubular cross section. An alternative embodiment is depicted in representation 10C, in which an inner former element 5 has an inner former surface 51 which extends in the upper half of the tubular cross section over two corner regions with reforming edge portions with a strong curvature 42 and also a reforming edge portion with a slight curvature 41 arranged therebetween. A further alternative embodiment is shown in representation 10D, in which each inner former element 5 has an inner former surface 51, which extend in a lateral region of the tubular cross section in each case over two corner regions with reforming edge portions with a strong curvature 42 and also a reforming edge portion with a small curvature 41 arranged therebetween. Another alternative embodiment is shown in depiction 10E, in which two inner former elements 5, each with an inner former surface 51, extend along a reforming edge portion with a strong curvature 42 in each case in the upper half of the tubular cross section.

LIST OF REFERENCE SIGNS

1 forming device

11 base plate

12 forming element

13 guide element

2 shoulder surface

3 prism surface

4 reforming edge

41 reforming edge portion with slight curvature

42 reforming edge portion with strong curvature

5 inner former element

51 inner former surface

6 actuator

7 material web

8 filler tube

A adjusting range of the inner former element

A1, A2 characteristic positions of the inner former element

G gap width

G1, G2 gap width in a characteristic position

Forming Device

Information

Publication Number

Date Filed

Date Published

Inventors

Original Assignees

CPC

International Classifications

Abstract

Description

Claims

Priority Claims (1)