EP1210220A1

EP1210220A1 - Method and device for guiding a web of material

Info

Publication number: EP1210220A1
Application number: EP00949476A
Authority: EP
Inventors: Dieter Mathieu; Wolfgang Rasp
Original assignee: Trespaphan GmbH and Co KG
Current assignee: Treofan Germany GmbH and Co KG
Priority date: 1999-08-16
Filing date: 2000-08-09
Publication date: 2002-06-05
Anticipated expiration: 2020-08-09
Also published as: WO2001012418A1; EP1210220B1; ZA200202138B; ATE293036T1; AU771910B2; DE50010054D1; MXPA02001673A; US6704978B1; DE19938165A1; AU6281400A

Abstract

The present invention relates to a method for guiding a flat web of material (1) in which the web of material (1) runs in an arrangement of rotating rollers at a web speed vF. The web of material is guided in its peripheral region via a spreader roll (2) which produces a tensile stress in the transverse direction, i.e. crosswise relative to the machine direction of the web of material (1), wherein this tension in the transverse direction is controlled by means of closed-loop control of the circumferential speed vR of the spreader roll (2) and/or by open-loop control of the cant angle alpha and/or of the wrap angle beta between the surface of the spreader roll (3) and the web of material (1) and wherein the circumferential speed vR is greater than the web speed vF.

Description

HOECHST TRESPAPHAN GMBH

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Method and device for guiding a material web

The invention relates to a method and a device for guiding a material web (1) which are guided and transported between rotating rollers.

In the manufacture and processing of sheet-like material webs, these webs are guided and transported between rotating rollers. A certain tensile stress is generated in the longitudinal direction of the material web for transporting the web. This tensile stress in the running direction can cause folds or warps in the longitudinal direction, which are undesirable and which later produce stretching in the winding, which can lead to the material being completely unusable. It is therefore necessary to keep the folds and distortions in the running material web caused by the tensile stress in the longitudinal direction smooth and wrinkle-free by tensile forces in the transverse direction.

Devices for keeping material webs wide are known in the prior art. US 22 89 196 describes the so-called banana roller. This cylindrical roller is at least on the surface made of a rubber-elastic material and specially shaped. The roller is bent over its entire length and is pressed against the running material web. The shape of the roller causes the width to be kept in the transverse direction when the roller is pressed into the running material web. However, the force transmission of transverse forces that can be generated and the transverse movement that can be achieved in this way is extremely low and therefore unusable for many applications.

The present invention is based on the object of a method and a device for keeping a sheet-like material web (1) wide is guided and transported over rollers. The method is intended to ensure that the material web (1) can be guided and transported in the longitudinal and transverse directions without creasing and stretching. It is particularly important here that the method can be adapted, ie the method should be used equally successfully at different speeds of the material web (1) and for different materials. In addition, the device should be low-maintenance and less prone to repairs.

This object is achieved by a method for guiding a sheet-like material web (1), in which the material web (1) runs in an arrangement of rotating rollers at a web speed v _F and the material web (1) in both edge areas via at least one spreader roll (2 ) is guided, which generates a tensile stress in the transverse direction, ie transverse to the running direction of the material web (1), this tension in the transverse direction by regulating the peripheral speed v _{R of} the spreader roll (2) and / or by controlling the angle and / or the Contact surface (3) between the roll surface (5) and the material web (1) is controlled and the peripheral speed of the spreader roll (2) is v _R > web speed v _F.

Fig. 1 shows the spreader roll (2) in a schematic cross-sectional view, wherein b _{g is} the total width of the spreader roll (2) and b is the outer surface of the roll.

Fig. 1 a shows a special embodiment of the spreader roll (2) also in a schematic cross-sectional view, in which the roll surface (5) is not rounded and is therefore particularly wide.

Fig. 2 shows the spreader roll (2) in the side view. Fig. 3 shows the spreader roll (2) from Fig. 1 in a perspective view.

3a shows the spreader roll (2) from FIG. 1a in a perspective view.

Fig. 4 shows the contact surface (3) of the spreader roll (2) to the material web (1).

Fig. 5 shows schematically the position of the spreader rolls (2) depending on the angle α to the material web (1). V _F represents the web speed and the arrow indicated the direction of travel of the material web (1).

Fig. 6 is a schematic representation in a side view of the material web (1) which is guided over the spreader roll (2). The angle ß results from the point of impact p of the material web (1) on the spreader roll (2) and the backward extension of the material web (1) behind the spreader roll (2), shown in broken lines. The immersion depth of the spreader roll (2) in the material web (1) is denoted by h. The direction of rotation of the spreader roll (2) and the running direction of the material web (1) are indicated by the arrows. V _R and V _F denote their speeds.

7 is a perspective illustration of the positioning of the spreader rolls (2) relative to the material web (1) as a function of the angle α. The arrangement of the spray electrodes (4) is also shown.

In the sense of the present invention, the longitudinal direction is the direction in which the material web (1) runs; this direction is also referred to as the machine direction. The transverse direction is that in the sense of the present invention Direction that is at an angle of 90 °, ie transverse to the machine direction.

In the manufacture and processing of sheet-like material webs, these webs are guided in an arrangement of rotating rollers. The peripheral speeds of the individual rolls are controlled and on the one hand determine the speed at which the web runs, and on the other hand the various roll speeds also specify a tensile stress which is introduced in the longitudinal direction of the material web. This tensile stress in the longitudinal direction is necessary in order to ensure trouble-free running of the material web over the rolls and the subsequent devices integrated in the roll arrangement, such as thickness measurement, corona station or the like.

The method according to the invention eliminates the disadvantages caused by the tensile stress introduced in the longitudinal direction. The method is suitable for various sheet-like material webs and can advantageously be used wherever wrinkling and / or warping occurs in the longitudinal direction of the material web when it is guided over and between rotating rollers. The method has proven itself in particular for foils made of plastics, in particular of thermoplastic plastics. Films made from thermoplastic materials are, for example, films made from polyester and polyolefins, such as polyethylenes, polypropylenes, cycloolefins, polycarbonate, polyamides, etc. Films of this type can be constructed in one or more layers. The method can also be used for webs made of other materials, such as fabric, paper or metal webs. The method is also advantageous when it comes to the production of laminates or when guiding the laminate itself. Different materials are also possible for the laminates. The method is particularly suitable for material webs with a thickness of 0.5 to 500 μm, preferably 2 to 200 μm, suitable.

The web speed v of the material web is determined by the desired production or processing speed. Depending on the type of material, usual web speeds are between 1 and 2500 m / min, preferably 5 to 1000 m / min. For films made of thermoplastic polymers, speeds of 100 to 1000 m / min are common. The longitudinal tensile stress to be introduced into the material web depends on the one hand on the material properties (e.g. material type) and their thickness or the purpose of the subsequent devices (e.g. thickness measurement, surface treatment, winding station), which are integrated or connected in the roller arrangement, and on the other hand the web speed v _F itself and the tensile stress to be applied depend on each other in the running direction. The entrained air of the material web forms air posters between the roller and the material web in front of the rollers, which must be pressed off by the tensile stress introduced into the material web. The higher the web speed, the easier it is to form undesirable air cushions and the higher the longitudinal tension generally has to be to squeeze these cushions out. Web speed and tension are thus predetermined parameters in the production and processing processes that can only be varied within a limited range, even if there are folds and warps in the longitudinal direction. These problems are effectively prevented by the method according to the invention, wherein web speed and tension can be kept in the desired range.

The method according to the invention is therefore particularly advantageous for productions or processing operations with high web speeds. According to the invention, the material web (1) is guided in its edge region over one or more spreader rolls (2). The edge area of a material web (1) is generally narrow in relation to the total width of the web. The GE- the exact width of such an edge area will depend on the type of material and the total width of the web. In general, an edge area is understood to mean the outer areas of the web, which together can make up up to 30% of the total width. In general, each edge area is 1 to 10% of the total width of the material web. It goes without saying that each endless web of material has two edges that run parallel to the direction of travel. The following information about "the edge area" naturally also applies in the same way to the opposite edge.

The material web (1) is guided in the edge area over a spreader roll (2). This spreader roll (2) is dimensioned such that its diameter is generally greater than its width b _g , so that the term "roll" characterizes the element more appropriately than the term "roller". However, it is not excluded that appropriately dimensioned rollers can also serve an equivalent purpose. The person skilled in the art will select the size of the element as a function of the material web (1), the web speed and the width of the edge area. In general, the spreader roll (2) has a width b _g of 1 to 500 mm, preferably 1 to 150 mm, in particular 1 to 50 mm. The diameter of the wide roll (2) is generally 1 to 10% of the web width (1). The material web width depends on the type of material and the specified machine dimensions and can therefore vary within a wide range. For films made of thermoplastics, the usual web widths in the production of the film before the transverse stretching are between 0.2 to 2 m, preferably 0.5 to 1 m, but after the transverse stretching 0.5 to 30 m, preferably 1 to 20 m. Accordingly, the absolute values of the roll diameter can vary within wide limits.

The spreader roll (2) can in principle be made of any material or material. composite material must be produced that meets the requirements. The surface should be designed such that a positive connection between the material web (1) and the roller surface (5) is promoted. In a special embodiment, it is necessary to apply the surface to zero electrical potential.

In a preferred embodiment, the roll is chamfered or rounded at the edges in such a way that the outer surface b _M becomes narrower, so that the contact surface (3) between the material web (1) and the roll surface (5) is ideally at one point or on a line is reduced. In general, the lateral surface b _M for beveled or rounded embodiments will have a width of 0 to 400 mm, preferably 1 to 200 mm. Rollers that are bevelled or rounded in this way are particularly advantageous since the relative movement between the outer surface b _M and the material web (1) becomes smaller and smaller as the outer surface decreases. In addition, bevelled or rounded rolls offer some protection against damage to the material web (1).

The spreader roll (2) does not necessarily need an independent drive. It can be driven via the running material web (1) and then has a peripheral speed v _R which corresponds to the web speed v _{F of} the material web (1) taking into account the angle of attack α. In a preferred embodiment, the spreader roll (2) is provided with a drive by means of which the peripheral speed of the roll V _R can be controlled or regulated. Spreader rolls driven in this way are preferred. The drive makes it possible to control or regulate the peripheral speed of the roller and also to control the tension generated in the transverse direction. For driven rollers, taking into account the angle of attack α, the peripheral speed v _R is set such that the peripheral speed v _{R is} at least as large, preferably larger than the web speed v _{F of} the material web (1). The advance of the peripheral speed v _{R of} the roll is generally set such that there is no relative movement between the roll surface (5) and the material web (1).

In a further preferred embodiment, the spreader roll (2) has an electrically conductive surface which is connected to an electrical zero potential. This surface enables a particularly advantageous embodiment of the method according to the invention, in which a non-positive connection between the contact surface of the spreader roll (2) and the material web (1) is achieved by electrostatically charging the material web (1). This embodiment of the method is explained in detail below.

To carry out the method according to the invention, the spreader rolls (2) are positioned in the two edge regions of the material web (1). The positioning of the spreader rolls (2) on the running material web (1) is chosen from a mechanical engineering and ergonomic point of view. Driven spreader rolls (2) are driven so that they rotate in the direction of travel of the material web (1). An angle of attack is set for positioning the roll in relation to the running direction of the web (see FIG. 7). This angle must be> 0 ° and <90 °. In general, you will set an angle of attack in the range of 2 to 50 °, preferably 5 to 30 °. The roller speed v _{R is} controlled or regulated by adjusting the angle. The control or regulation of the individual parameters is dependent on one another. For example, the following relationship applies between the angle of attack α to be set and the peripheral speed of the roller v _R :

v _R = v _F : cos. Thus, with a larger angle of attack α, a larger peripheral speed v _{R must be} selected if there is to be no relative movement between the material web (1) and the roller surface (5).

Finally, the spreader rolls (2) are positioned in the third possible spatial direction. First, the roll must be brought so far in the direction of the material web (1) that the roller surface (5) dips into the material web (1). This positioning is also referred to below as the installation depth h (see FIG. 6). The immersion depths of the spreader roll (2) in the running material web (1) determine how far the material web (1) wraps around the spreader roll (2). The higher the wrap angle ß, the more contact surface (3) is created between the roller surface (5) and the material web (1).

In a further, particularly advantageous embodiment of the invention, the frictional wrap around the roll is supported by an electrostatic charge on the material web (1). For this purpose, as seen in the direction of travel of the material web (1), a spray electrode (4) is attached in the region of the point of impact P of the material web (1) on the spreader roll (2) (see FIGS. 6 and 7). An electrical charge is applied to the material web (1) in a small area via this spray electrode (4). If the material web (1) thus loaded then runs over an electrically conductive spreader roller (2) which is switched to electrical zero potential, the material web (1) is attracted to the surface of the spreader roller (5). This leads to a particularly good, non-positive connection between the material web (1) and the contact surface (3), possibly also to a larger wrap angle β. This gives the person skilled in the art another parameter by means of which he can dose the force in the transverse direction. The higher the charging voltage, the greater the contact force and given If not, the wrap angle β, which ultimately eliminates the possible slippage between the material web (1) and the contact surface (3) and a transverse force can be built up by leading the spreader roll (2).

The invention opens up a simple way of introducing a tensile stress in the transverse direction of a running material web. This method is particularly advantageous since it offers various possibilities for controlling this tension in the transverse direction. The tension can be controlled by controlling the roll diameter, the angle of attack α, the immersion depth h, the design of the roll surface, the peripheral speed, the positioning of the spreader roll to the material web, and the static charge. This enables a very fine metering of the forces acting in the transverse direction via various specifications. The method according to the invention is extremely flexible and can advantageously be used for a wide variety of materials and production or processing methods. It enables material webs to be wrinkle-free between rotating rollers and to build up a controlled tensile stress in the transverse direction, so that warping or other disturbances which can arise from the tensions in the longitudinal direction can be reliably avoided.

Claims

claims

1. A method for guiding a sheet-like material web (1), in which the material web (1) runs in an arrangement of rotating rollers at a web speed v _F , characterized in that the material web (1) in its edge region via a spreader roll (2) is guided, which generates a tensile stress in the transverse direction, ie transverse to the running direction of the material web (1), this tension in the transverse direction by regulating the peripheral speed v _{R of} the spreader roller (2) and / or by controlling the angle of attack α and / or Wrap angle ß is controlled and wherein the peripheral speed v _R > web speed v _F.

2. The method according to claim 1, characterized in that the material web (1) is a material web made of a thermoplastic, preferably polyester, polyethylene, polycarbonate, polypropylene or a cycloolefin polymer.

3. The method according to claim 1 and / or 2, characterized in that the material web (1) has a thickness of 0.5 to 500 microns, preferably 2 to 200 microns.

4. The method according to one or more of claims 1 to 3, characterized in that the web speed v _{F of} the material web (1) 1 to

Is 2000 m / min.

5. The method according to one or more of claims 1 to 3, characterized in that each edge region is 1 to 10% of the total width of the material web (1).

6. The method according to one or more of claims 1 to 6, characterized in that the spreader roll (2) has a diameter in the range of 1 to 500 mm and the diameter is greater than the width of the spreader roll (2).

7. The method according to one or more of claims 1 to 7, characterized in that the surface of the spreader roll (5) consists of a metallic, conductive surface and an electrical zero potential is applied.

8. The method according to one or more of claims 1 to 8, characterized in that the spreader roll (2) has chamfered or rounded edges.

9. The method according to one or more of claims 1 to 9, characterized in that the spreader roll (2) is connected to a drive which enables regulation of the peripheral speed V _{R of} the spreader roll (2).

10. The method according to one or more of claims 1 to 10, characterized in that at least two spreader rolls (2) are positioned in the two opposite edge regions of the material web (1) and form an angle to the edge of the material web (1) which> 0 ° and <90 °, preferably 2 to 50 °.

11. The method according to one or more of claims 1 to 11, characterized in that the spreader roll (2) is immersed in the material web (1) such that the material web (1) at least partially wraps around the spreader roll (2).

12. The method according to one or more of claims 1 to 12, characterized in that a spray electrode (4) is arranged in the region of the point of impact on the spreader roll (2) such that a load is applied to the material web (1) and the Spreader roll (2) has a conductive surface (5).