WO2015055713A1

WO2015055713A1 - Winding shaft

Info

Publication number: WO2015055713A1
Application number: PCT/EP2014/072108
Authority: WO
Inventors: Frank Hoffmann
Original assignee: Windmöller & Hölscher Kg
Priority date: 2013-10-15
Filing date: 2014-10-15
Publication date: 2015-04-23
Also published as: EP3057897A1; US20160229662A1; CN105849021A; CN105849021B

Abstract

The invention relates to a tensioning shaft for winding a material web, in particular of plastic films, namely in particular of stretch films. In order to provide a tensioning shaft having the highest possible strength and rigidity, a tensioning shaft is provided which has a shaft body which in order to achieve the highest possible bending stiffness consists predominantly of fibre-reinforced plastic, and having cavities which are provided along the external circumference of the shaft body, wherein the cavities are delimited in the radial internal direction by a layer of the fibre-reinforced plastic are and wherein tensioning strips are expandable out of the cavities in the radial external direction.

Description

winding shaft

The invention relates to a tensioning shaft for winding a material web, in particular of plastic films, in particular of stretch films. Moreover, the invention relates to a method for producing such a tensioning shaft and a winder with such a tensioning shaft.

Winding shafts consisting of a clamping shaft and a winding tube for winding and / or unwinding of web-shaped, band-shaped or filamentary materials of various kinds, such as paper, aluminum and plastic films, textiles or non-woven fabrics or the like, are well known and specific to the particular application aligned or turned off on the specific winding technique.

The inclusion of the winding tube in a corresponding winder is usually done on expanding clamping bars or clamping jaws with a mechanical or pneumatic control, which cause a centric clamping of the winding tube and allow a drive of the winding tube, even with high torques.

Special requirements for the winding shaft in turn arise when winding so-called stretch films.

Depending on the application, stretch films - also called load unit securing foil, pallet stretch film, stretch wrap film or stretch wrapping film - have become indispensable in modern logistics when transporting palletized loading units. In addition to securing the pallets, such films also protect the pallet goods from the effects of weathering and contamination. The stretch film optimally adapts to the pallet and product shape without damaging it. For the application of Stretch film are now also various semi or fully automatic stretcher for "Einstretchen" the stacked range available.

Stretch films are produced in a wide variety of thicknesses and widths. Typically, for example, film thicknesses between 12-35 μηι with a roll width of 200 mm - 1000 mm, preferably 500 mm, which are delivered to 10 - 20 kg rolls.

With currently approx. 1.5 million tonnes per annum across Europe and approx. 3.0 million tonnes per annum worldwide, the stretch film market will continue to enjoy a significant volume share in the future. The requirements for the production of stretch films are therefore constantly increasing with regard to efficiency and output. The winder, which winds the finished stretch film onto a winding tube at the end of the production line, must also meet these increasing demands. Here, a winding tube over the entire production width can be used. Mostly, however, several cores are used side by side, the stretch film is then divided before winding on the cores then by appropriate knives in the direction of production. For example, with a production width of 1500 mm, three benefits per 500 mm are moved in parallel and wound up.

The cores themselves are usually made of a cardboard tube and can be very different depending on the application in width, inner diameter and outer diameter and thus also in terms of their wall thickness.

In order to be able to wind the produced stretch film on the winding tubes for all applications, the winder in question has a so-called tensioning shaft with controllable clamping jaws for radial clamping of the respective winding tubes. However, since it is not known in advance with which type of cores the tensioning shaft is loaded, the tensioning shaft must be designed for all possible types of operating cases. At the same time, it should be noted that due to the properties described, the stretch film to be wound up has a high extensibility of up to 400%. This leads to extreme demands on the clamping shaft. From WO2013 / 003968 A9 a winder is known in which the tensioning shaft is mounted on both sides in a double bearing in order to prevent undesired vibrations of the tensioning shaft and at the same time to permit high rotational accelerations. In order to achieve a high flexural rigidity and at the same time a small outside diameter for the tensioning shaft, it is also known to manufacture tensioning shafts completely or partially from fiber composite materials, as described, for example, in WO 2005/124212 A1 or in US Pat. No. 5,746,387. Composite fiber tensioning shafts usually consist of a plastic or crosslinked resin material (reaction resin) containing reinforcing fibers, for example natural fibers, glass fibers (GRP composite) or carbon fibers (CFRP composite material) in the form of finite-length fragments, continuous fibers, mats or fabrics. Composite materials with broken fibers are in particular extruded endlessly or processed by injection molding. Continuous fiber composites are processed into tubes or tubes, in particular by filament winding or pultrusion. Particularly suitable are so-called CFRP shafts (CFRP for carbon fiber reinforced plastic or English CFRP for carbon fiber reinforced plastic). CFRP regularly consists of oriented continuous fibers that are embedded in a plastic matrix, usually in several layers. However, the required for the clamping strips recesses undesirably reduce the strength and rigidity of the clamping shaft.

The object of the invention is therefore to provide a clamping shaft with the highest possible strength and rigidity. This object is achieved by a tensioning shaft for winding a material web, with a shaft body, which consists to achieve the highest possible bending stiffness for the most part of fiber-reinforced plastic, and with cavities, which are provided along the outer circumference of the shaft body, wherein the cavities in the radial inner direction are limited by a layer of the fiber-reinforced plastic and wherein from the cavities in the radial outer direction clamping strips are expandable. An essential finding of the invention is that the cavities for the clamping strips do not consist of radially continuous recesses, but are limited in the radial inner direction by a layer of fiber-reinforced plastic. In this way, the strength and rigidity of the tensioning shaft can be effectively increased.

According to a preferred embodiment it is provided that the fiber-reinforced plastic consists of directional continuous fibers which are connected by means of a cured resin.

According to a further preferred embodiment, it is provided that the oriented continuous fibers consist of carbon fibers.

According to a further preferred embodiment it is provided that the clamping bars have at their radial end cup-shaped elements which consist of plastic and / or a fiber composite material.

A possible method for producing the tensioning shaft according to the invention is a method in which moldings are provided for receiving radially expandable tensioning strips, around which endless fibers are layered, wherein the shaped bodies lie in radial inner direction on at least one layer with directed continuous fibers, in which the shaped bodies are joined together with the continuous fibers by means of a cured resin, and in which after curing of the resin, the radially expandable clamping strips are introduced into the moldings.

The moldings may for example consist of aluminum or plastic. Thus, the moldings sit as firmly as possible in their fits, the moldings can be glued in addition to the adhesive force on the part of the resin and / or screwed.

Another possible method for producing the tensioning shaft according to the invention is a method in which a shaft body to achieve the highest possible flexural rigidity for the most part is made of fiber-reinforced plastic, in which cavities are milled along the circumference of the shaft body, wherein the cavities in the radial inner direction by a Layer of the fiber-reinforced plastic are limited, and are introduced in the radially expandable clamping bars in the cavities. The winder for winding a material web with the tensioning shaft according to the invention is preferably a winder with a bearing arrangement arranged on at least one side of the tensioning shaft, in which the respective end of the tensioning shaft is mounted in two spaced-apart areas.

According to a preferred embodiment arranged on both sides of the tensioning shaft bearing assemblies are provided, in which the ends of the tensioning shaft are mounted, wherein each of the two bearing assemblies supports the associated end of the tensioning shaft in two spaced-apart areas.

According to a further preferred embodiment, at least one winding sleeve enclosing the clamping shaft is provided, which can be fixed by means of the expanding clamping strips relative to the clamping shaft.

The advantages of the invention are overall a higher strength and rigidity of the tensioning shaft and their storage, which permanently higher production speeds due to a higher critical bending speed are possible.

Further details and advantages of the invention will be described with reference to the accompanying drawings. In these show:

Fig. 1 shows a winding shaft with an unfavorable orientation of the cavities

Respect to the continuous fibers,

2 shows a winding shaft with an alignment of the cavities on obliquely running continuous fibers, FIG. 3 shows a winding shaft with an alignment of the cavities on axially extending

Continuous fibers,

Fig. 4, the two-sided storage of a clamping shaft with double bearings, and Fig. 5 is a section through a clamping shaft according to the invention. First, the orientation of the cavities with respect to the filaments will be described.

If the tensioning shaft is produced with endless fibers in the winding process (filament winding), then it should be noted that a parallel alignment of the endless fibers to the axis is not possible due to the machine-side limitations present during the production of the winding sleeve. Rather, only alignments up to about 7 ° to the axial direction are possible. If now - as shown in Fig. 1 - the recesses of the cavities are still aligned axially, then this has a negative impact on the strength and rigidity of the clamping shaft with respect to the intersecting endless fibers.

Fig. 1 shows the left half of a winding shaft with a tensioning shaft 101. The winding shaft has axially aligned cavities 102, in the clamping bars can be introduced, which can be pressed pneumatically to the outside and are optionally traced back by spring force. The orientation of a first layer of continuous fibers is indicated by 103 and the orientation of a second layer of continuous fibers within the tensioning shaft is indicated by 104. Since the cavities shorten the filaments 103 and 104, this alignment of the cavities has a negative influence on the strength and rigidity of the tensioning shaft.

Fig. 2 shows a winding shaft with a tensioning shaft 201 and with an alignment of the cavities on oblique continuous fibers. The reference numerals 201, 203 and 204 correspond to the reference numerals 101, 103 and 104, so that reference can be made in this regard to the description of FIG. 1. However, the cavities 202 are now aligned along the directional continuous fibers 204, so that the said negative influence on the strength and rigidity of the tensioning shaft can be reduced. FIG. 3 shows a winding shaft with a specially manufactured tensioning shaft 301, as is known, for example, from WO 2005/124212 A1. The reference numerals 301 and 302 correspond to the reference numerals 101 and 102 of FIG. 1, so that reference can be made in this regard to the description of FIG. 1. The tensioning shaft is now made so that the directed endless fibers 303 extend axially to the tensioning shaft 301 and to the axially aligned cavities 302. This is possible according to WO 2005/124212 A1 through the use of stiffening ribs, which were produced in the pultrusion process and which have a particularly high Allow fiber volume fraction. In a corresponding manner, the cavities are aligned.

Fig. 4 shows the two-sided storage of a clamping shaft with double bearings, as this is known from WO 2013/003968 A9. However, WO 2013/003968 A9 does not disclose the combination of a double bearing with a tensioning shaft made of fiber-reinforced plastic. This combination is also particularly advantageous from the point of view of the invention. The tensioning shaft 401 made of CFRP is therefore firmly clamped in the double bearing 402 on the left side. The bearing assembly 403 is also designed as a double bearing, however, this bearing assembly is detachable via a two-armed scissor unit, so that one or more cores can be pushed from the right onto the clamping shaft or removed from this again after the scissor unit has pivoted the bearing assembly 403. 5 shows a section through a tensioning shaft according to the invention on fiber-reinforced plastic. The clamping shaft 501 has five cavities along its circumference, in which pneumatic hoses 502 and movable clamping bars 503 are introduced. In the radial inner direction, the cavities are limited by a layer of fiber-reinforced plastic, so that sets the desired stiffness of the clamping shaft. Optionally - but not necessarily - the clamping bars 503 are also biased with spring elements that bring the clamping bars in the position shown in FIG. 5a, as soon as enough air has escaped from the tubes 502. As far as the clamping bars 503 are not biased, the clamping bars 503 are at escaped air in a position between the respective stops, but without a torque can be transmitted to the outer winding tube.

If, starting from the state according to FIG. 5 a, the hoses 502 are filled with compressed air, the state according to FIG. 5 b occurs, after which the clamping bars 503 are extended and can exert a radial force on the outer winding tube.

The clamping bars 503 can extend continuously in the axial direction over the entire clamping shaft. Alternatively, it is just as possible that the clamping bars of several smaller elements, the number of which is chosen so that enough torque can be transmitted to the outer winding tube. The tensioning shaft 501 itself can be made entirely of fiber-reinforced plastic or consist of a hybrid structure with a fiber-reinforced plastic and a metal.

List of Reference Strips

Cavity or clamping bar

Orientation of a first layer of continuous fibers Orientation of a second layer of continuous fibers

Cavity or clamping bar

Directed continuous fiber tensioning shaft

Bearing arrangement, fixed

Bearing arrangement, detachable tensioning shaft

pneumatic hoses

clamping bar

Claims

Winding shaft claims

1 . Tensioning shaft for winding a material web,

with a shaft body consisting to a maximum of flexural rigidity to a large extent of fiber reinforced plastic, and with cavities provided along the outer circumference of the shaft body, wherein the cavities are limited in the radial inner direction by a layer of fiber reinforced plastic and from the cavities in the radial outer direction clamping strips are expandable.

2. tensioning shaft according to claim 1, wherein the fiber-reinforced plastic consists of directed continuous fibers which are connected by means of a cured resin.

3. tensioning shaft according to one of claims 1 - 2, wherein the directional continuous fibers consist of carbon fibers.

4. tensioning shaft according to one of claims 1 - 3, wherein the clamping bars have at its radial end cup-shaped elements which consist of plastic and / or a fiber composite material.

5. A method for producing a tensioning shaft according to claim 1, wherein the shaped bodies are provided for receiving radially expandable clamping strips around which endless fibers are layered, wherein the shaped bodies lie in the radial inner direction on at least one layer with directed endless fibers, in which the shaped bodies together be connected to the continuous fibers by means of a cured resin, and in which after curing of the resin, the radially expandable clamping bars are introduced into the moldings.

6. A method for producing a tensioning shaft according to claim 1, wherein a shaft body to achieve the highest possible bending stiffness for the most part is made of fiber-reinforced plastic, in which cavities are milled along the circumference of the shaft body, wherein the cavities in the radial inner direction by a Layer of the fiber-reinforced plastic are limited, and are introduced in the radially expandable clamping bars in the cavities.

7. winder for winding a material web, with a tensioning shaft according to claim 1, with a arranged on at least one side of the tensioning shaft bearing assembly in which the respective end of the tensioning shaft is mounted in two spaced-apart areas. Winder according to claim 7, arranged on both sides of the tensioning shaft bearing assemblies in which the ends of the tensioning shaft are mounted, wherein each of the two bearing assemblies supports the associated end of the tensioning shaft in two spaced-apart areas.

Winder according to one of claims 7 - 8, with at least one winding shaft enclosing the winding sleeve, which is fixable by means of the expanding clamping strips relative to the clamping shaft.