Device for cutting a covering and method for using

Abstract

Device for cutting a covering in a machine for producing a fibrous web, wherein the device comprises a knife holder (1) and a knife (2), and wherein the knife holder comprises means (3) for attaching a pulling device, and wherein the device comprises a spacer element (6) and a first and a second sliding plate (4, 5) each with a sliding surface, and wherein the sliding surfaces of the sliding plates are arranged parallel and facing each other, and wherein the first sliding plate is directly connected to the knife holder and the second sliding plate is connected to the knife holder by means of the spacer element, and wherein the knife comprises a blade with at least one cutting edge, and wherein the knife is connected to the knife holder such that the at least one cutting edge is at an acute angle of less than or equal to 60°,to the sliding surfaces and extends at least from the sliding surface of the first sliding plate to the sliding surface of the second sliding plate.

Description

[0001] The invention relates to a device for cutting a fabric covering. Fabric coverings are used in machines for producing fibrous webs, e.g., in paper machines, and must be replaced regularly due to wear. These fabric coverings are, in particular, forming screens, which are used in the wire section of machines for producing fibrous webs. Other examples of fabric coverings in machines for producing fibrous webs are press felts and dryer screens. The device according to the invention is described below in connection with forming screens, but this is not to be understood as a limitation. The invention further relates to a method for using such a device in a machine for producing fibrous webs.

[0002] Machines for producing fibrous webs typically include several forming screens in the forming section. These are subject to wear and tear and therefore need to be replaced every 2-5 months. Since forming screens are manufactured as an endless belt and fed into the machine, they must be cut across the web to remove them. Usually, the worn forming screens are cut by hand with a standard utility knife by the operator and, if necessary, removed from the machine in several pieces. This requires crossing the machine section, exposing the operator to a significant risk of falls, as suitable walkways or crossing points are not usually provided. To prevent this danger, the inventors set themselves the task of making the usual manual procedure safer by means of a suitable device.

[0003] Devices for cutting textile webs transversely to the web direction are known in the prior art. For example, DE 20 2006 007 293 U1 discloses such a device. The disclosed device comprises a counter-holder, which is designed as a stationary cutting strip, and a circular blade which is set into rotation solely by contact with the cutting strip when the blade holder is moved along the cutting direction. When using such a device for cutting forming screens, the cutting strip would have to be at least as long as the web width of the forming screens to be cut. Since forming screens of machines for producing fibrous webs usually have a web width of several meters, the device disclosed in DE 20 2006 007 293 U1 would be very unwieldy for mobile use.

[0004] The object of the invention is to provide a device for cutting a covering that is more convenient and simpler in design. Furthermore, the object of the invention is to provide a method for using such a device.

[0005] The problem is solved according to the invention by an embodiment according to the independent claims. Further advantageous embodiments of the present invention are found in the dependent claims.

[0006] The inventors were guided by the idea that the device should be suitable for mobile use on various fabrics of one or more machines for producing fibrous webs. Furthermore, the device should be easy to handle and ensure that no other parts of the machine are damaged during use.

[0007] The invention will be explained below with the aid of figures. The figures show, in detail: Fig. 1: Device according to the invention in a first view Fig. 2: Device according to the invention in a second view Fig. 3: Unfolded device according to the invention

[0008] The figures show a device according to the invention in a preferred embodiment. Alternative embodiments are discussed below in connection with the preferred embodiment, without explicitly mentioning further modifications that are obvious to those skilled in the art.

[0009] Fig. Figure 1 shows a device according to the invention in a first view. The upper part of Fig. 1 a side view and the lower part of Fig. 1. A view from above. The direction "from above" is indicated by the upper part of the Fig. 1 defined. The device comprises a knife holder, designated 1, and a knife, designated 2, which is connected to the knife holder 1. Preferably, the greater part of the knife 2 is arranged inside the knife holder 1. In the Fig. In the embodiment shown in Figure 1, the part of the knife 2 which is arranged inside the knife holder 1 is indicated by dashed lines.

[0010] The knife holder 1 includes means for attaching a pulling device. Advantageously, the pulling device consists of a rope. Alternatively, the pulling device could also be designed as a rod or telescopic rod. Fig. 1. These means are designed as eyelets and are labelled 3. The pulling device is used to pull the device in the cutting direction during the cut. Fig. The direction of cutting is indicated by the arrow. In the following, the terms "front" and "rear" refer to the direction of cutting. It is advantageous if the means 3 for attaching a pulling device are located at the front of the device.

[0011] The device according to the invention is designed to cut a forming screen in a section where the screen runs horizontally. The horizontal orientation of the forming screen gives rise to the terminology used below, such as "above," "below," "over," and "below," which each refer to the forming screen being cut. During cutting, the device is moved essentially transversely to the direction of travel. It is irrelevant if the actual direction of movement of the device deviates from the ideal transverse direction, since the cut forming screen must be disposed of in any case. To ensure that the device follows the forming screen during this movement, it comprises two sliding plates, each with a sliding surface. The sliding surfaces are arranged parallel to each other and facing each other. Minor deviations from parallelism are negligible.Furthermore, the term "sliding plate" should not be understood as restricting the elements in question to being strictly plate-shaped. They can also deviate from the strict plate shape, for example, by being slightly wedge-shaped or by having a curved surface opposite the sliding surface. Fig. 1 is a first sliding plate designated 4 and a second sliding plate designated 5. The sliding plates 4 and 5 are connected to the knife holder 1, with the first sliding plate 4 being directly connected to the knife holder 1, and the connection of the second sliding plate 5 to the knife holder 1 being made by a spacer element designated 6. The spacer element 6 defines the distance between the two sliding surfaces. The sliding plates 4 and 5 are designed so that the forming sieve to be cut runs between the two sliding plates 4 and 5. Therefore, the distance must be chosen so that a forming sieve has sufficient space between the sliding plates 4 and 5. On the other hand, an excessively large distance can lead to the device tilting during the cutting process.It is also conceivable to cut two forming screens simultaneously with a device according to the invention, since there are screen sections where two forming screens run close together, between which the fiber web is guided during operation. In this case, the distance between them should be chosen to be somewhat larger. However, such a cut of two forming screens only makes sense if both screens are worn out at the same time. The device according to the invention is also suitable for cutting only one of two adjacent forming screens without damaging the other forming screen.

[0012] In the embodiment shown in the figures, the sliding plate 4, which is directly connected to the knife holder 1, is larger than the sliding plate 5. The reverse could also be true, or both sliding plates could be the same size. In any case, it is advantageous if the upper sliding plate, i.e., the sliding plate intended to be guided over the top of the forming screen to be cut, has a sufficiently large size, because it is primarily responsible for stable guidance of the device during cutting, as the upper sliding plate is pressed against the forming screen by the force of gravity acting on the device.

[0013] In the embodiment shown in the figures, the first sliding plate 4 is designed to be guided over the forming screen during cutting. Therefore, the knife holder 1 is also positioned above the forming screen during cutting. This is advantageous if the forming screen to be cut is positioned at a height that allows the operator to pull the device over the forming screen in this orientation. If the forming screen is positioned very high in the area to be cut, it may be advantageous to guide the device along the forming screen in the opposite orientation, i.e., if the knife holder 1 is positioned below the forming screen during cutting. In this orientation, the second sliding plate 5 shown in the figures would be positioned on top.If a device is to be used in both orientations, it is advantageous if both sliding plates are sufficiently large to ensure stable guidance in both orientations. It is also advantageous if the corners of sliding plates 4 and 5 are rounded, as this prevents the device from easily catching on any lateral obstacles during cutting.

[0014] The knife 2 comprises a blade with at least one cutting edge. The cutting edge can be straight or slightly curved. Commercially available blades with a straight cutting edge can advantageously be used. It is further advantageous if the knife 2 consists of only one blade, so that the knife holder 1 is directly connected to the blade and functions as a blade holder. Alternatively, the knife 2 can also comprise a separate blade holder connected to the blade. In this case, the knife holder 1 can be connected to the separate blade holder. In any case, the knife 2 is connected to the knife holder 1 such that the at least one cutting edge of the knife 2 runs at an acute angle of less than or equal to 60° to the sliding surfaces of the sliding plates. Preferably, the acute angle is less than or equal to 45°. The acute angle ensures that the forming sieve is cut in a pulling motion.The cutting edge of the knife 2 extends at least from the sliding surface of the first sliding plate 4 to the sliding surface of the second sliding plate 5. It is advantageous if the cutting edge projects a short distance into the second sliding plate 5. For this purpose, a groove or a continuous slot can be provided in the sliding plate 5 at the appropriate location. To prevent the knife 2 from making unwanted cuts, the cutting edge must not project beyond the surface of the second sliding plate 5 opposite the sliding surface. The second sliding plate 5 therefore also serves as a blade guard or cutting edge protector. The blade of the knife 2 can advantageously comprise more than one cutting edge, as indicated in the figures, so that the knife can be installed in a rotated position if one of the cutting edges becomes dull.Since only a part of the cutting edge is used for cutting at any given time, the arrangement shown in the figures even allows for four times the use of the same blade until it becomes dull.

[0015] The two extended lateral surfaces of the blade define a planar space. It is advantageous if the spacer element 6 is at least partially located within this space. The spacer element 6 then fulfills a function similar to the riving knife in a table saw, i.e., it keeps the two separate areas of the forming screen apart so that the blade cannot be pinched between them. Since a forming screen is very flexible, this function is of minor importance in a device according to the invention. For the same reason, a slight displacement of the spacer element 6 from the aforementioned space is acceptable, particularly if the distance between the blade and the spacer element is large. However, to enable the smoothest possible cut, it is advantageous if the spacer element 6 is located centrally within the aforementioned space and projects only slightly beyond it laterally.In this case, it is advantageous if the spacer element 6 is wedge-shaped on the side facing the knife 2. The cutting edge of the knife 2, which extends between the sliding surfaces, is oriented towards the means 3 for attaching a pulling device. The spacer element 6 is also arranged on the side of the knife 2 facing away from the means 3 for attaching a pulling device. That is, viewed against the cutting direction, the arrangement of the device elements is as follows (from front to back): means 3 for attaching a pulling device, cutting edge of the knife 2, spacer element 6.

[0016] The dashed line in the lower part of the Fig. 1 indicates that the knife holder 1 can be made in two parts (see also Fig. 3) In this case, the knife 2 can be positioned between the two parts of the knife holder 1. A recess can be provided in one or both parts of the knife holder 1, into which the knife 2 fits and is held in the desired orientation. Alternatively, the knife holder 1 can be a single piece. In this case, it is advantageous if the knife holder 1 includes a recess for the knife. The knife holder can then also include a cover that can be attached to the knife holder and that covers most of the knife and holds it securely in the recess. The knife can also be held in the desired orientation by means of pins in the knife holder 1 that engage in corresponding holes in the knife, as indicated in the figures. These pins can also be combined with recesses. In this case, the pins perform the function of holding the knife 2 in the desired orientation.The knife holder may also include additional recesses and / or pins into which the knife can be inserted when the device is not in use, so that the cutting edge is protected and located entirely inside the knife holder. Furthermore, spare blades can be stored in another recess.

[0017] If the knife holder is made in two parts, then it is advantageous if the first sliding plate 4 is also made in two parts. Then each wing of the sliding plate 4 is connected to a part of the knife holder. In the lower part of the Fig. The wings of the sliding plate 4 are designated 4.1 and 4.2. In principle, the second sliding plate 5 could also be made in two parts. However, this would then require the spacer element 6 to also be made in two parts. Since the spacer element 6 is preferably narrow (not much thicker than the blade of the knife 2), making the spacer element 6 in two parts would compromise the stability of the device. Therefore, it is advantageous if the second sliding plate 5 and the spacer element 6 are made in one piece. The spacer element 6 is then connected to one of the parts of the knife holder 1. If the knife is arranged in a recess in a part of the knife holder 1, it is advantageous if the spacer element 6 is connected to this part of the knife holder 1, as this facilitates the alignment and centering of the spacer element 6 with the knife blade.Then this part of the knife holder 1 can also be made thicker than the other part of the knife holder 1. In . Fig. The two wings are arranged laterally on the parts of the knife holder 1, with the underside of the knife holder 1 forming part of the sliding surface of the first sliding plate. They could also be attached to the underside of these parts, in which case it is advantageous if the wings are arranged in recesses of the parts. In both cases, the part of the knife holder 1 that projects beyond the first sliding plate 4 in the cutting direction can advantageously form an enlargement of the sliding surface of the first sliding plate 4 with its underside. Fig. 2 shows the device according to the invention Fig. 1, wherein in the upper part of the Fig. 2. The device is shown viewed from the other side. The lower part of the Fig. Figure 2 shows the device from below. The second sliding plate 5 is now shown from above. Its shape resembles an iron with rounded corners. This wedge-shaped design facilitates threading the forming sieve into the space between the two sliding surfaces and makes it more difficult for it to snag on any obstacles. The recess in the second sliding plate 5 (top left) is advantageous if the knife holder 1 is made in two parts and if the two parts of the knife holder 1 can be pivoted relative to each other, as shown in Fig. 3 shown. In the upper part of the Fig. 2 indicates a rope attached to eyelet 3. Fig. Figure 3 shows a device according to the invention with a two-part knife holder in a side view. The rear (first) part of the knife holder 1 is designated 1.1 and the front (second) part of the knife holder is designated 1.2. In the Fig. In the state of the device shown in Figure 3, the two parts 1.1 and 1.2 of the knife holder are pivoted apart. This state serves for inserting, removing, or replacing the knife 2. To pivot the two parts 1.1 and 1.2 relative to each other, the device includes a pivot axis, which is designated 7. In the embodiment shown, the pivot axis 7 is located at the rear bottom of the device. It could also be located elsewhere. The knife 2, the spacer element 6, and the second sliding plate 5 connected to it are connected to the first part 1.1 of the knife holder. In this way, the second part 1.2 of the knife holder acts as a cover for the knife 2. Advantageously, the knife can be arranged in a recess in the first part 1.1 of the knife holder. Fig.3. Both parts 1.1 and 1.2 have an eyelet that comes into contact when the parts are pivoted together. The eyelet, or another means for attaching a pulling device, could just as easily be located on only one part of the knife holder 1. The other part could then be shorter. In the pivoted position, the two parts 1.1 and 1.2 can be fixed in place using a suitable fixing device. This could be done, for example, with a wing nut or a screw with a knob. Another possibility is the use of a locking bolt.

[0018] The following describes the method for using a device according to the invention in a machine for producing a fibrous web with a covering. The method comprises the following steps: - Inserting a pulling device into the machine for the production of a fibrous web; - Attaching the device to the pulling device; - Threading the covering into the space between the sliding surfaces of the device; - Moving the device with the aid of the pulling device, whereby the covering is cut by the device.

[0019] The first three steps, which prepare for the actual cutting process, can be performed in any order. The actual cutting process takes place in the fourth step.

[0020] The first step involves inserting the pulling device into the machine from one side, with one end of the device extending far enough into the machine to be grasped from the opposite side. If the pulling device is a rope, it can be thrown from one side of the machine to the other, provided there is sufficient space (e.g., a gap). Alternatively, the rope can be attached to a pole or telescopic rod and pushed through a gap in the machine. It is advantageous to have two people available to perform this step.For the fourth step, it is also advantageous to have two people available, as it facilitates the process if one person holds the device at its rear end at the beginning of the cutting process while the other person pulls the device using the pulling device. However, the procedure can also be carried out by just one person. Reference symbol list 1 knife holder 1.1 First part of the knife holder 1.2 Second part of the knife holder 2 knives 3 Means for attaching a pulling device 4 First sliding plate 4.1 Wing of the first sliding plate 4.2 Wings of the first sliding plate 5 Second sliding plate 6 spacer elements 7 Swivel axis QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] DE 20 2006 007 293 U1

[0003]

Claims

[1] Device for cutting a covering in a machine for producing a fibrous web, wherein the device comprises a knife holder (1) and a knife (2) connected to the knife holder (1), and wherein the knife holder (1) comprises means (3) for attaching a pulling device, characterized bythat the device comprises a spacer element (6) and a first and a second sliding plate (4, 5), each with a sliding surface, and wherein the sliding surfaces of the sliding plates (4, 5) are arranged parallel and facing each other, and wherein the first sliding plate (4) is directly connected to the knife holder (1) and the second sliding plate (5) is connected to the knife holder (1) by means of the spacer element (6), and wherein the knife (2) comprises a blade with at least one cutting edge, and wherein the knife (2) is connected to the knife holder (1) such that the at least one cutting edge runs at an acute angle of less than or equal to 60° to the sliding surfaces and extends at least from the sliding surface of the first sliding plate (4) to the sliding surface of the second sliding plate (5), and wherein the at least one cutting edge is oriented towards the means (3) for attaching a pulling device,and wherein the spacer element (6) is arranged behind the cutting edge when viewed from the means (3) for attaching a pulling device. [2] Device according to claim 1, wherein the acute angle is less than or equal to 45°. [3] Device according to claim 1 or 2, wherein the knife holder (1) is made in one piece and the knife (2) is arranged in a recess of the knife holder (1). [4] Device according to claim 1 or 2, wherein the knife holder (1) is made in two parts and comprises a first part (1.1) and a second part (1.2), and wherein the knife (2) is arranged between the first part (1.1) and the second part (1.2), and wherein the first sliding plate (4) comprises a first wing (4.1) and a second wing (4.2), and wherein the first wing (4.1) is connected to the first part (1.1) and the second wing (4.2) is connected to the second part (1.2). [5] Device according to claim 4, wherein the device comprises a pivot axis (7) for pivoting the second part (1.2) relative to the first part (1.1). [6] A method for using a device according to one of the preceding claims in a machine for producing a fibrous web with a covering, comprising the following steps: - Inserting a pulling device into the machine for the production of a fibrous web; - Attaching the device to the pulling device; - Threading the covering into a space between the sliding surfaces of the device; - Moving the device with the aid of the pulling device, whereby the covering is cut by the device.

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