RETRACTOR DEVICE

Abstract

The invention involves a spreading device (1) for multiple material sheet strips (4) cut from a material sheet (5) by a material sheet cutting device. The material sheet strips (4) are fed to the spreading device (1) along a transport path in order to be subsequently transported, offset parallel to one another, to a winding shaft arrangement and to be wound onto a common winding shaft. The spreading device (1) comprises two deflection elements (2 and 3), which each extend transversely to the transport path and are configured and arranged such that a strip spacing (9) between two adjacent to one another along a transport path are successively enlarged over the first and second deflection elements (2 and 3) of the guided material sheet strips (4). The deflection elements (2, 3) are arranged in a rotationally fixed manner. Each deflection element (2 and 3) comprises a number of openings (15) in a transport contact area (13) of a deflection sheath surface (12) of the deflection elements (2 and 3) covered by the material sheet strips (4) transported over it, through which compressed air can be blown in order to create a friction-reducing air layer between the material sheet strips (4) and the deflection sheath surfaces (12) of the deflection elements (2 and 3) in the transport contact area (13).

Description

The invention relates to a spreading device for multiple material sheet strips separated from a material sheet by a material sheet cutting device, whereby the material sheet strips are fed along a transport path in a feed plane of the spreading device and leave the spreading device in a discharge plane in order to then be transported parallel to one another to a winding shaft arrangement and wound up on a common winding shaft. The spreading device comprises two deflection elements, which each extend transversely to the transport path and are configured and arranged such that a strip spacing between two material sheet strips guided adjacent to one another along a transport path one after the other over the first and second deflection elements is larger in the discharge plane than in the feed plane.

In practice, numerous material sheet cutting devices are known, using which multiple material sheet strips arranged next to each another can be produced from a material sheet which, e.g., consists of a paper material or a plastic film, which are then each wound onto a winding shaft and kept ready for later use. In this context, is must be ensured that two material sheet strips arranged next to one another and originating from the common material sheet are sufficiently separated from one another once the winding up is completed in order to ensure that each individual wound material sheet strip roll is able to be separated from the adjacent material sheet strip roll, and that the material sheet strip rolls which are so produced can be stored individually of one another for subsequent use.

Known cutting systems comprise a winding shaft arrangement consisting of two or more winding shafts. Once the cutting process is complete, the separated adjacent material sheet strips are each fed to different winding shafts upon which they are wound up. As adjacent material sheet strip rolls are wound onto different winding shafts, sufficient distance can be specified without little effort. If at the same time a larger number of material sheet strip rolls are produced at the same time and a number of adjacent material sheet strip rolls are wound on to a common winding shaft but were not originally juxtaposed, the distance between two material sheet strip rolls wound on the same winding shaft should correspond to at least a distance of a width of the width of the originally material sheet strip rolls wound on a different winding shaft. However, it is considered disadvantageous that the material sheet strips coming from a material sheet have to be wound onto two or more different winding shafts.

It is also in practice known that a material sheet that has not yet been separated into multiple material sheet strips is, e.g., pulled apart transversely to a direction of the transport path using a spreader roller before cutting. The material sheet is then fed to the material sheet cutting device with a transverse tension predetermined by the spreader rollers and separated into multiple material sheet strips. After completing the cutting process, the individual separated material sheet strips lose their transverse tension contracting slightly, this creates a small gap between the two adjacently arranged material sheet strips. As the number of individual material sheet strips that are separated from the material sheet increases, the individual gaps created between two adjacent material sheet strips reduces again and again, this increases an undesirable tendency for the material sheet strips transported and wound juxtaposed inevitably to collide or run into one another.

It is also already known that a spreading device is arranged downstream of the material sheet cutting device, with which the material sheet strips transported side by side along the transport path are spread before they are wound up in the winding shaft arrangement. Rotating mounted spreader rollers are used to achieve the desired spread of the material sheet strips, these often have an individual number of individual roller segments, via which the individual material sheet strips are deflected and spread or separated from one another, thereby increasing the strip spacing between two adjacent material sheet strips. Particularly with narrow cuts, in which a large number of comparatively narrow material strips are produced from a material sheet, conventional spreader rollers can no longer have an assigned individual segment for each individual material sheet strip. This causes distorting of the material sheet strips during transport over the spreader roller, which can lead to undesirable transverse tensions within a material sheet strip causing a lateral offset along the further transport path of the material sheet strip. It has also been demonstrated that a spreading effect and thus a distance created by the spreading of two adjacent material sheet strips depends on a sheet tension generated along the transport path, which is necessary for the transport of the material sheet strips along the transport path. Particularly during acceleration and deceleration processes, which occur during the operation of such systems, this sheet tension generated along the transport direction cannot be reliably kept constant, which in turn can lead to lateral displacement of the individual material sheet strips. An unwanted misalignment can also be caused by friction generated during the transport of the individual material sheet strips over the spreader roller. Because of the friction and wear and tear of the spreading device over its service life, additional deviations can occur in the deflection of the individual material sheet strips caused by the spreading device, which in turn can impair reliable separation of the individual material sheet strips.

Therefore, the object of the present invention is to configure a spreading device already known from the prior art such that material sheet strips transported in a juxtaposed manner through the spreading device are spread out as reliably as possible and causing sufficient distance between them so that they can then be wound onto a common winding shaft without neighbouring wound material sheet strip rolls touching each other.

According to the invention, this object is achieved by arranging the deflection elements in a rotationally fixed manner, and by each deflection element comprising a number of openings in a transport contact area of the deflection sheath surface covered by the material sheet strips transported over it, compressed air can be blown out through this in order to be able to produce a friction-reducing air layer between the material sheet strips and the deflection sheath surfaces of the deflection elements in the transport contact area. A precisely defined geometry of the deflection sheath surfaces of the deflection elements which are deflecting the individual material sheet strips relative to the material sheet strips transported over them and deflected in the process can also be specified over a long service life of the spreading device due the deflection elements being arranged in a rotationally fixed manner, without this geometry being impaired by a conventionally known rotational movement of the deflection elements or an insufficiently precise bearing of the rotating deflection elements. Using the embodiment of an air layer between the transport contact areas of the deflection sheath surfaces of the deflection elements on the one hand and the material sheet strips transported over them on the other, friction between the material sheet strips on the one hand and the stationary deflection sheath surfaces of the deflection elements on the other can be reduced considerably. This reduces undesirable friction-induced wear and tear of the deflection elements such that no significant change in the shape of the deflection sheath surfaces over the specified service life of the spreading device, or a service life limited by wear and tear of the deflection elements can be significantly extended.

This friction-reducing layer of air between the deflection sheath surfaces of the deflection elements and the material sheet strips being transported over them and deflected along the deflection sheath surfaces also reduces undesirable transverse tension and distortion of individual material sheet strips, resulting in a significantly reduced unwanted lateral offset of individual material sheet strips after leaving the spreading device.

Regarding the embodiment of an air layer that is as homogeneous as possible and which does not impair the desired deflection of the individual material sheet strips, a large number of openings should be provided within the transport contact areas in the deflection sheath surfaces of the deflection elements. The individual openings can be arranged and formed regularly or irregularly across the transport contact areas. Air pressure of the compressed air supplied to each deflection element is appropriately specified such that, on the one hand, the embodiment of a friction-reducing layer of air is achieved throughout the entire transport contact area of the deflection sheath surface and, on the other hand, the minimum possible distance is created between the deflection sheath surface and the material sheet strips being transported over it so that the deflection and lateral displacement of the material sheet strips resulting from the geometry of the deflection sheath surfaces is not impaired.

According to an advantageous embodiment of the inventive concept, the deflection sheath surfaces of the deflection elements are made of a porous and air-permeable material. A suitable porous material can, e.g., be produced from a powder or granulate by a sintering process. It is also conceivable that the porous material is produced by foaming a ceramic or a suitable plastic or metal material. One sheath element or multiple sheath elements can be manufactured from the porous and air-permeable material and provided for each deflection element, whereby an outer side of the sheath element or plurality of sheath elements forms the deflection sheath surface of the respective deflection element. The respective transport contact surface within the deflection sheath surfaces is made of the porous and air-permeable material, if, depending on the arrangement and use of the deflection elements, the material sheet strips are not in contact with the deflection element over the entire deflection sheath surface, but only in a partial area of the transport contact surface or are transported past it and thus deflected.

According to one alternative embodiment of the inventive concept, the deflection sheath surfaces or the transport contact surface of the deflection elements are made from a perforated sheet or from a perforated thin-walled material layer. There are known procedures that can be used to make or form very small holes having a small opening diameter in a sheet or in a layer of material. For example, a high-energy laser can be used to make small holes in a thin sheet of metal or a layer of plastic. Using a pulsed laser, a large number of holes can be created in a short time. Suitable laser drilling devices are known in the industry. The deflection sheath surfaces or the transport contact surfaces of the deflection elements can also be manufactured from another suitable material, such as a plastic or a composite material consisting of multiple layers of material arranged over one another or next to one another, instead of a sheet metal. This material should have as smooth and low-friction a surface as possible and create as minimal abrasion as possible during operation so that the deflection elements are operated at low wear over a long service life and the material sheet strips can glide over the deflection sheath surfaces or the transport contact surfaces at a high sheet speed.

In an advantageous manner, the deflection sheath surfaces or the transport contact surfaces of the deflection elements are optionally configured to have a number of holes having an opening diameter of less than 0.5 mm, preferably less than 0.2 mm. Evidence has demonstrated that the highest possible number of exceptionally small holes can be used to produce a particularly homogeneous and precisely controllable layer of air across the entire transport contact areas of the deflection sheath surfaces, which is used to effectively reduce the friction of the material sheet strips passing over it. The cross-sectional area of the holes can be approximately circular or oval, elliptical or polygonal. Using a suitable orientation of non-circular cross-sectional areas relative to the transport path, specified for a number of holes or for all holes, relevant characteristics of the air layer formed can be positively influenced and predetermined.

The desired shape and geometry of the deflection sheath surfaces for the deflection of the material sheet strips can either be created during the manufacture of the sheath elements or later by shaping the individual sheath elements and thus be predetermined with extreme precision. As a result of the rotationally fixed arrangement of the individual deflection elements, the arrangement and alignment of the deflection elements and consequently also of the individual deflection sheath surfaces can be specified with extreme precision so that the individual material sheet strips can be deflected by the spreading device in the most ideal, distortion-free manner possible.

According to one advantageous method, there is the option of arranging and configuring the two deflection elements such that the feed plane and the discharge plane are offset parallel to each other. The greater the offset of the feed plane and the discharge plane for the material sheet strips transported along the transport path, the greater the distance which can be specified between neighbouring material sheet strips. However, it has been demonstrated that an offset of less than 20 centimetres between the feed plane and the discharge plane is adequate to create a sufficient distance, even with a large number of material sheet strips cut from a common material sheet. The deflection elements are conveniently configured such that the material sheet strips are transported between the two deflection elements at least approximately at a right angle relative to the feed plane and the discharge plane. Depending on the original width of the material sheet and the quantity of material sheet strips separated from this material sheet, a slightly less pronounced deflection may also be sufficient and appropriate.

According to one advantageous embodiment of the inventive concept, it is provided that the deflection elements are configured in the shape of a segment of a circle in a cross-sectional area extending along the transport path. To deflect a material sheet strip by around 90 degrees, all that is needed is a correspondingly large segment of a formed deflection sheath surface, for example in the shape of a circular arc, which extends over an arc angle of slightly more than 90 degrees. As the deflection elements are arranged so that they cannot rotate, it is not necessary to make the deflection elements cylinder shaped. Only the transport contact area provided for the deflection of the material sheet strips and the necessary deflection sheath surfaces is required. The circular segment-shaped embodiment leads to a uniform deflection of the material sheet strips over the transport contact areas of the deflection sheath surfaces, resulting in the most uniform possible stress on the material sheet strips during transport by the spreading device. The circular segment-shaped formed deflection elements can also be arranged to save space within a larger system, with which a material sheet can be unwound from a material sheet roll and separated into individual material sheet strips so that the individual material sheet strips can then be rewound onto material sheet strip rolls. Instead of a deflection sheath surface curved in the shape of a circular arc, another shape such as an oval or elliptical shape may also be suitable.

It has proven to be especially advantageous for the spreading of the individual material sheet strips that a deflection sheath surface of each deflection element feature a deflection curvature along the transport path of a material sheet strip and a spreading curvature extending across all material sheet strips transversely to the transport path. The spreading curvature can be formed constant across the transport path. The deflection curvature specified along the transport path can also be constant and identical for all material sheet strips. It is also conceivable that a separate deflection curvature is specified for each material sheet strip. The deflection curvature can also be different within a material sheet strip depending on the width of the material sheet strips and the material of the material sheet strips, if this favours a reliable spreading of the individual material sheet strips relative to each other and a subsequent undesired lateral offset can be reduced. The desired geometry and shape of the deflection sheath surface can be precisely specified and produced by shaping the porous and air-permeable material, for example by manufacturing the deflection sheath surface from a porous and air-permeable material.

It is also conceivable that the spreading curvature of a deflection element, which extends across all material sheet strips, is formed by subsequently reshaping a deflection element blank that is not initially curved in a spreading direction. For many applications, a required or useful spreading curvature is relatively small and a spreading curvature radius is often orders of magnitude larger than an extension of the deflection element transverse to the transport path of the material sheet strips. Experience has demonstrated that the desired spreading curvature can be generated and specified by subsequent forming of a deflection element blank, particularly with deflection elements whose deflection sheath surface or transport contact surface is formed by a perforated sheet or a perforated material layer. The deflection element blank can initially be produced in one direction, which makes it much easier and cheaper to manufacture. Forming processes are known to exist in industry that can be used to precisely generate very large radii of expansion curvature and specify them for the formed deflection element.

It has proved to be a particularly advantageous embodiment of the inventive concept that the deflection sheath surfaces of the two deflection elements along the transport path form an equally sized wrap-around section for each material sheet strip. Using a circular segment embodiment of the deflection elements, the wrap-around section of each material sheet strip is made up of the two wrap-around brackets that are specified by the transport path for a material sheet strip along the two deflection sheath surfaces of the deflection elements. Using wrap-around sections of the same size, at least for neighbouring or all material sheet strips, promotes uniform sheet tension along the transport path and consequently also enables simple and reliable control of the sheet tension for the most uniform and reliable transport of the material sheet strips along the transport path.

Various exemplary embodiments of the inventive concept are explained in more detail hereinafter and are shown schematically and by way of example in the drawings. Shown are:

FIG. 1: a perspective view of a spreading device comprising two deflection elements, whereby multiple material sheet strips arranged adjacent to one another are guided along a transport path around the deflection elements and deflected in the process

FIG. 2: a top view of a deflection element,

FIG. 3: a sectional view through the deflection element shown in FIG. 2 along a sectional line III-III in FIG. 2,

FIG. 4: a sectional view through a differently configured deflection element,

FIG. 5: a sectional view of another differently configured deflection element, and

FIG. 6: a top view of a deflection element produced by forming and shown by way of example in FIG. 5

FIG. 1 is, by way of example, an illustration of one spreading device 1 embodiment. The spreading device 1 comprises a first deflection element 2 and a second deflection element 3. A material sheet 5 that has already been separated into multiple material sheet strips 4 is fed to the spreading device 1 at a feed plane 6. The material sheet strips 4 are each deflected by the two deflection elements 2, 3 and leave the spreading device 1 in a discharge plane 7 that is offset parallel to the feed plane 6. During transport along a transport path indicated by an arrow 8, the material sheet strips 4 are not only deflected by the deflection elements 2 and 3, but are also spread out relative to one another, so that in the discharge plane 7 a strip spacing 9 between neighbouring material sheet strips 4 is greater than the strip spacing in the feed plane 6 before entering the spreading device 1.

Each of the two deflection elements 2 and 3 extends transversely to the transport path over the entire width of the fed material sheet 5, or over the entire width of the spread material sheet strips 4. The deflection elements 2 and 3 have a circular arc segment shape in a cross-sectional area extending along the transport path, as also shown schematically in FIG. 3. Each deflection element 2 and 3 comprises a base body 10 and a sheath element 11 made of a porous and air-permeable material. An outwardly directed outer surface of the sheath element 11 forms a deflection sheath surface 12 for the material sheet strips 4 transported over the deflection elements 2 and 3, which rest against the deflection sheath surface 12 within a transport contact area 13 of the deflection sheath surface 12, separated only by a narrow air cushion, and are thus deflected. The transport contact area 13 or transport contact surface is the area of the deflection sheath surface 12 against which the material sheet strips 4 rest during transport along the transport path. The transport contact area 13 can coincide with the deflection sheath surface 12 or be a partial area of the deflection sheath surface 12.

The sheath element 11 is fixed to the base body 10 of the deflection elements 2 and 3 such that an interior space 14 is formed between the sheath element 11 and the base body 10. Compressed air can be fed into the interior space 14 and is then blown out through the large number of individual openings 15 in the porous material of the sheath element 11 and escapes. As a result, a friction-reducing layer of air is formed in the transport contact area 13 between the deflection sheath surface 12 and the material sheet strips 4 transported over it.

The deflection sheath surface 12 of the deflection elements 2 and 3 formed by the sheath element 11 features an expanding curvature extending transversely to the transport path across all material sheet strips 4, which is recognisable as the outer contour 16 of the sheath element 11 in a top view of a deflection elements 2 and 3 shown in FIG. 2. In the exemplary embodiment shown in the drawings, the spreading curvature is constant over the entire extension of the deflection elements 2 and 3 transverse to the transport path. For practical purposes, a radius of curvature of several metres is often sufficient and the splay curvature in the illustration in FIG. 2 is only shown clearly exaggerated for illustration purposes.

FIGS. 4 and 5 show examples of further variants of a deflection elements 2 and 3. In the embodiment shown in FIG. 4, the deflection elements 2 and 3 have an arc-shaped sheath element 11 made of a porous material, which is placed on the base body 10. The shape of the base body 10 is predetermined in the areas adjacent to the sheath element 11 such that a continuous and approximately stepless and seamless surface is formed at the transition from the base body 10 to the deflection sheath surface 12 formed by the sheath element 11.

Multiple funnel-shaped interior spaces 14 are formed in the base body 10 adjacent to the sheath element 11, which almost completely cover a contact surface 17 of the sheath element 11 facing the base body 10. Compressed air can be blown into the sheath element 11 over a large area through these interior spaces 14, which forms a friction-reducing air layer for the material sheet strips 4 sliding over it after exiting through the porous material of the sheath element 11. The compressed air can, for example, be supplied via compressed air lines 18, which are fitted and pressed into compressed air ducts 19 formed in the base body 10.

In an embodiment shown schematically in FIG. 5, the deflection elements 2 and 3 comprise a perforated plate 20 that is curved along the transport path along a quarter circle. The perforated plate 20 is made from a thin sheet into which a large number of spaced holes 21 were subsequently drilled using a laser drilling device. An opening diameter of the holes 21 is preferably significantly smaller than 0.5 mm. The perforated plate 20 is connected to the base body 10 along a circumferential edge 22. A transition from the base body 10 to the perforated plate 20 is specified with as little friction as possible.

The base body 10 can, for example, have a shape as illustrated schematically and by way of example in FIG. 5. It is also possible for the base body 10 to have a tubular shape, with a slot extending in the longitudinal direction, into which the perforated plate 20 is fitted.

The deflection elements 2 and 3, which are only shown schematically in FIG. 6, is formed from a straight-lined forming blank by a forming process that creates the spreading curvature. The forming blank is initially produced in a straight line in a longitudinal direction of the deflection elements 2 and 3, which extends perpendicular to a cross-sectional area of the deflection elements 2 and 3 shown in FIGS. 3 to 5, which can be achieved with regard to the base body 10, for example, by strand extrusion or by a suitable low-cost forming process. The deflection element blank, which is initially produced in a straight line, can then be deformed by a suitable forming step and provided with the required expansion curvature. This forming step can also be performed very precisely and at the same time cost-effectively, so that it is possible to manufacture the deflection elements 2 and 3 in a way that is particularly advantageous from an economic point of view.

Claims

1. A spreading device (1) for multiple material sheet strips (4) cut from a material sheet (5) by a material sheet cutting device, wherein the material sheet strips (4) are fed to the spreading device (1) along a transport path in a feed plane (6) and leave the spreading device (1) in a discharge plane (7) in order to be subsequently transported, offset parallel to one another, to a winding shaft arrangement and to be wound onto a common winding shaft, wherein the spreading device (1) comprises two deflection elements (2 and 3), which each extend transversely to the transport path and are configured and arranged such that a strip spacing (9) between two material sheet strips (4) guided adjacent to one another along a transport path in succession over the first and second deflection elements (2 and 3) is greater in the discharge plane (7) than in the feed plane (6), wherein the deflection elements (2 and 3) are arranged to be non-rotatable, and in that each deflection element (2 and 3) comprises a number of openings (15) in a transport contact area (13) of a deflection sheath surface (12) of the deflection elements (2 and 3) covered by the material sheet strips (4) transported thereover, through which compressed air can be blown in order to create a friction-reducing air layer between the material sheet strips (4) and the deflection sheath surfaces (12) of the deflection elements (2 and 3) in the transport contact area (13), wherein: the two deflection elements (2, 3) are arranged and configured such that the feed plane (6) and the discharge plane (7) are offset parallel to each other, andthe deflection elements (2, 3) are configured such that the material sheet strips (4) are transported between the two deflection elements (2, 3) at least approximately at a right angle relative to the feed plane (6) and the discharge plane (7).

2. The spreading device (1) according to claim 1, characterised in that the deflection sheath surfaces (12) or the transport contact surfaces (13) of the deflection elements (2 and 3) are made of a porous and air-permeable material.

3. The spreading device (1) according to claim 1, characterised in that the deflection sheath surfaces (12) or the transport contact surfaces (13) of the deflection elements (2 and 3) are made from a perforated sheet metal or from a perforated thin-walled material layer.

4. The spreading device (1) according to claim 3, characterised in that the deflection sheath surfaces (12) or the transport contact surfaces (13) of the deflection elements (2 and 3) have a number of holes with an opening diameter of less than 0.5 mm, preferably less than 0.2 mm.

5. The spreading device (1) according to claim 1, characterised in that the two deflection elements (2 and 3) are arranged and designed configured such that the feed plane (6) and the discharge plane (7) are offset parallel to one another.

6. The spreading device (1) according to claim 1, characterised in that the deflection elements (2 and 3) are configured in the shape of a segment of a circle in a cross-sectional area extending along the transport path.

7. The spreading device (1) according to claim 1, characterised in that a deflection sheath surface (12) of each deflection element (2 and 3) has a deflection curvature along the transport path of a material sheet strip (4) and, transversely to the transport path, a deflection curvature extending over all material sheet strips (4).

8. The spreading device (1) according to claim 7, characterised in that the spreading curvature of a deflection element (2 and 3) which extends over all material sheet strips (4) is formed by subsequent reshaping of a deflection element blank that is not initially curved in a spreading direction.

9. The spreading device (1) according to claim 1, characterised in that the deflection sheath surfaces (12) of the two deflection elements (2 and 3) form a wrap-around section of the same size for each material sheet strip (4) along the transport path.