METHOD FOR CROSS-CUTTING A MATERIAL WEB MOVED ALONG A DIRECTION OF MOVEMENT AND DEVICE THEREFORE

Abstract

The invention relates to a method for cross-cutting a material web (1), in particular a pulp web or the like, that is moved in a direction of movement (2), wherein the material web (1) is moved through between two axes of rotation oriented approximately perpendicularly to the direction of movement (2), about which axes of rotation cooperating blades (3, 4) are moved with a rotary movement, said blades (3, 4) cutting the material web (1) approximately perpendicularly to the direction of movement (2) as said material web (1) passes through between the axes of rotation. In order to achieve a high-quality cut edge with little noise pollution and high system availability, the invention provides that, after the material web (1) has been cut, a force is applied to a part of the material web (1) that is carried along with a blade (3, 4) and in particular a part of the material web (1) that bears against a blade (3, 4), in order to separate the material web (1) from the rotary movement of the blade (3, 4). Furthermore, the invention relates to a device for cross-cutting a material web (1) that is moved in a direction of movement (2), having at least two cooperating blades (3, 4), which are rotatable about axes of rotation arranged approximately perpendicularly to the direction of movement (2), wherein the material web (1) is movable through between the axes of rotation, such that the material web (1) is able to be cut by the blades (3, 4) approximately transversely to the direction of movement (2).

Claims

1. A method for cross-cutting a material web moved along a direction of movement, in particular a pulp web or the like, wherein the material web is moved between two rotational axes oriented roughly perpendicular to the direction of movement, wherein cooperating blades are moved around these rotational axes with a rotational movement, cutting the material web roughly perpendicular to the direction of movement as it passes through between the rotational axes, wherein, after the material web has been cut, a force is applied to a part of the material web that is carried along with a blade, in particular one that abuts against a blade, so as to detach the material web from the rotational movement of the blade, wherein the circumferential speed of the blades is less than the speed the material web along the direction of movement.

2. The method according to claim 1, wherein the force is applied with a spring.

3. The method according to claim 2, wherein the spring is tensioned by a relative movement of the two blades during each rotation of the blades before the blades cut the material web.

4. The method according to claim 1, wherein the force is pneumatically applied.

5. The method according to claim 1, wherein the force is hydraulically applied.

6. The method according to claim 1, wherein the force is applied with an apparatus connected with the blade in a corotating manner, with the part of the material web being detached from said blade.

7. The method according to claim 1, wherein the blades rotate inversely.

8. (canceled)

9. A device for cross-cutting a material web moved along a direction of movement in a method according to claim 1, with at least two cooperating blades, which can be rotated around rotational axes arranged roughly perpendicular to the direction of movement, wherein the material web can be moved through between the rotational axes, so that the material web can be out by the blades roughly transverse to the direction of movement, wherein an apparatus is provided with which a force can be applied to a part of the material web that is carried along with a blade, in particular one that abuts against a blade, so as to detach the material web moved along with the blade from the blade.

10. The device according to claim 9, wherein the apparatus has a spring, which is arranged in such a way that the spring is tensioned with the device operating as intended by a relative movement of the two blades, before the blades reach an engaged position in which the blades cut the material web.

11. The device according to claim 9, wherein the blades are arranged in such a way that the blades are spaced apart from each other in the direction of movement in an engaged position, so that one blade comprises a leading blade, and one blade comprises a trailing blade.

12. The device according to claim 11, wherein the apparatus is designed to apply a force to a part of the material web that is carried along with the leading blade.

13. The device according to claim 11, wherein, the leading blade has a roughly radially oriented rear surface.

14. The device according to claim 9, wherein the apparatus is arranged on a rear surface of the blade.

15. The device according to claim 9, wherein the blades are arranged in such a way that the blades overlap each other in a radial direction in an engaged position.

16. The device according to claim 9, wherein the apparatus has a contact element that is connected with the blade in a radial direction via a spring, and in particular consists of a wear-resistant material.

17. The device according to claim 9, wherein the apparatus has an electromechanically acting actuator.

18. The device according to claim 9, wherein, the apparatus is designed for pneumatic activation.

19. The device according to claim 9, wherein the apparatus is designed for hydraulic activation.

Description

[0033] Examples of additional features, advantages and effects may be gleaned based on the following exemplary embodiments described below. The drawings to which reference is here made show:

[0034] FIGS. 1 to 3 different procedural states of a method for cross-cutting a material web;

[0035] FIGS. 4 to 6 different procedural states of a method according to the invention for cross-cutting a material web;

[0036] FIGS. 7 to 15 various devices according to the invention in detail.

[0037] FIGS. 1 to 3 each present schematic views of a section through part of a device for cross-cutting a moved material web, wherein FIG. 1 shows a point in time before a cross-cut, FIG. 2 shows an engaged position, in which a cross-cut or separation of the material web 1 takes place, and FIG. 3 shows a point in time after a cut.

[0038] As evident, two cooperating cutting edges formed by a respective one front surface 5 and one rear surface 6 of a blade 3, 4 are arranged on two cooperating cutting rollers 10, 11, which rotate inversely around rotational axes (not depicted) and in the engaged position shown on FIG. 2 cut or separate the material web 1 transverse to the direction of movement 2 of the material web 1. The roughly parallel rotational axes are arranged above and below or on either side of the material web 1, and on the figures are oriented perpendicular to a drawing plane, so that the material web 1 usually driven by conveying means like conveyor rollers is moved through between the rotational axes.

[0039] The blades 3, 4 of the cutting rollers 10, 11 are here arranged offset, so that the blade 3 of the counterclockwise rotating, upper rotating roller 10 on FIGS. 1 to 3 forms a leading blade 3, and the blade 4 of the clockwise rotating, lower cutting roller 11 forms a trailing blade 4. This prevents the cutting edges formed by a respective front surface 5 and rear surface 6 from becoming damaged by coming into contact with each other during a cut through the material web 1.

[0040] A method described on FIGS. 1 to 3 is used to cut a pliable material web, for example which can be designed as a pulp web, transverse to the direction of movement 2, meaning perpendicular to the drawing plane, wherein the circumferential speed of the blades 3, 4 around the rotational axes roughly corresponds to the speed of the material web 1 along the direction of movement 2.

[0041] When manufacturing sheets of varying length, the rotational speed of the cutting rollers 10, 11 is usually reduced in order to cut longer sheets. As a result, the speed of the material web 1 in the direction of moment 2 is higher than the speed of the blades 3, 4 in the circumferential direction, which is why the material web 1, after making a cross-cut, slides over the inclined, rear surface 6 of the trailing blade 4 onto the rear surface 6 of the leading blade 3 oriented radially to the upper cutting roller 10, and subsequently abuts against the rear surface 6 of the leading blade 3, Because the speed of the material web 1 or the conveying means with which the material web 1 is driven before reaching the cutting rollers 10, 11 is higher by comparison with the speed of the blades 3, 4, the material web 1 is here pressed against the rear surface 6 of the leading blade 3, and owing to the resultant contact force 12 between the material web 1 and leading blade 3 can be moved along with this leading blade 3 as evident on FIG. 3. As a result, the material web 1 can become bent or curried, and a jam can form, making it necessary to stop the production process. As depicted, the contact force 12 acting on the material web 1 is oriented opposite the direction of movement 2 and toward the upper cutting roller 10.

[0042] In order to prevent the material web 1 from moving along with the leading blade 3 or to detach the material web 1 from the leading blade 3, the invention provides an apparatus, which is used to expose the material web 1 to a force, which detaches the material web 1 from the leading blade 3.

[0043] FIGS. 4 to 6 present a schematic view of a device according to the invention along with various states of a method according to the invention. As evident, the apparatus is here arranged on a rear surface 6 of the leading blade 3, and comprises a spring here exemplarily formed by a coil spring 7, which as the cutting rollers 10, 11 rotate is radially inwardly tensioned by a relative movement of the blades 3, 4. After the cutting rollers 10, 11 have reached the engagement point depicted on FIG. 5, the distance between the blades 3, 4 again increases, so that the coil spring 7 can be relaxed. The material web 1 is here pressed away from the rear surface 6 of the leading blade 3 by means of the coil spring 7 via a contact element 8 connected with the coil spring 7, and can thus continue to freely move along an ideal path after the cutting rollers 10, 11, which runs roughly in the direction of movement 2. The contact element 8 that presses the coil spring 7 onto the material web 1 and with the trailing blade 4 applies a force for tensioning the coil spring 7 usually consists of a wear-resistant material, preferably a wear-resistant plastic. Since the device according to the invention can also be used in wide pulp webs measuring several meters, several coil springs 7 can of course be arranged over the width of the device, i.e., perpendicular to the drawing plane and parallel to the rotational axis, so as to correspondingly spring load a contact element 8 designed with a corresponding length, so that a force can be applied over the entire width for detaching the material web 1.

[0044] After a cut, the material web 1 thus slides transverse to the direction of movement 2 through the rear surface 6 of the trailing blade 4 arranged at an angle a of less than 90° to the front surface 5 of the trailing blade 4 onto the roughly radially oriented rear surface 6 of the leading blade 3, from which the material web 1 is pressed radially outward with the apparatus, and thereby detached.

[0045] The apparatus can basically be designed in a variety of ways. FIG. 7 presents an exemplary embodiment of a device according to the invention, in which the apparatus has a spring formed by an elastic element 9. The elastic element 9 is here compressed up to the engagement point by the trailing blade 4 as the cutting rollers 10, 11 rotate, and relaxed after the engagement point, so as to apply a radial force to the material web 1 abutting against the rear surface 6 of the leading blade 3, and detach the material web 1 from the leading blade 3.

[0046] FIG. 8 shows another embodiment of the invention, wherein the apparatus has a hose 13 that can be filled with air. In this embodiment of the invention, the hose 13 is filled with air, so that the latter forms a spring, which is tensioned before an engaged position is reached by a cooperation between the two blades 3, 4 or a cooperation between the two cutting rollers 10, 11, and which detaches the material web 1 from the leading blade 3 after the engaged position has been reached.

[0047] FIG. 9 shows another embodiment of the invention. According to this embodiment, the apparatus has a hydraulic element 14, which can be designed to be actively activated or to be tensioned via the trailing blade 4, so as to apply a force to the material web 1 in a radial direction upon reaching the engaged position, and detach the latter from the leading blade 3.

[0048] FIG. 10 shows another embodiment of the invention. According to this embodiment, an actively activatable blade holder 15 is provided on the leading blade 3. A force for detaching the material web 1 from the leading blade 3 is thus applied upon activation of the blade holder 15 while retracting the leading blade 3 after the engaged position over a trailing part of the upper cutting roller 10, so that the material web 1 is detached from the leading blade 3 by the trailing part of the upper cutting roller 10.

[0049] FIG. 11 shows another embodiment of the invention, in which the apparatus has an elastic cover plate 18. The elastic cover plate 16 is tensioned or moved radially inward by a cooperation between the two cutting rollers 10, 11 before the engaged position is reached, and relaxed after the engaged position has been reached, so that the elastic cover plate 16 applies a radially outward force to the material web 1 as viewed from the upper cutting roller 10 that carries the leading blade 3, and the material web 1 is pressed away from the rear surface 6 of the leading blade 3.

[0050] FIG. 12 shows another embodiment of the invention, in which the apparatus has a nozzle 17 connected with a compressed air line 18, through which compressed air can be applied to the material web 1 after the engaged position has been reached. In a device designed in such a way, the material web 1 is thus detached from the leading blade 3 by compressed air.

[0051] FIG. 13 shows another embodiment of the invention, in which the apparatus comprises an element 19 which can be moved radially relative to the upper cutting roller 10 that carries the leading blade 3, and is moved radially outward after the engaged position by centrifugal force and gravitational force, so as to press the material web 1 away from the leading glade 3.

[0052] FIGS. 14 and 15 show other embodiments of the invention, in which the apparatus has a respective mechanical lever 20 mounted in the upper cutting roller 10 so that it can be rotates around a lever axis 21 for applying a force via a contact element B. As evident in the exemplary embodiments on FIGS. 14 and 15, the lever 20 can here have a varying length, so as to apply an outward radial force to the material web 1 and detach the latter from the blade.

[0053] Even though the respective apparatus in the depicted exemplary embodiments is arranged on the upper cutting roller 10, it goes without saying that it can also be positioned on the lower cutting roller 11 so as to detach the material web 1.

[0054] A method according to the invention makes it possible to cross-cut a material web 1 to varying lengths, in particular during pulp production, resulting in an advantageously smooth cut on the one hand, and a minimal risk of a jam along with a low noise generation on the other. Detaching the material web 1 from the blade 3 with an applied force reliably prevents a jamming of the material web 1, and thus a blockade of an entire system. As a consequence, the method and the device according to the invention are also suitable for wide material webs 1 with a speed in the direction of movement 2 exceeding 100 m/min. This also makes it possible to easily use a twin-screw cross-cutter for varying sheet lengths.