Filter screen, tubular filter, filtering device and manufacturing method

Abstract

A filter screen for a tubular filter (2) for filtering liquids, particularly plastic melts (24), wherein the tubular filter screen (4) formed by bending a flat screen blank (19) has: a filter axis (3); a screen wall (11) having perforated regions (13) on the circumference of the screen wall, the perforated regions having densely arranged, fine through holes (14); and connecting portions (17) oriented in the axial direction. The perforated regions have region edges (15) extending in the axial direction at both ends in the circumferential direction, wherein the region edges terminate at a distance in front of the connecting portion when forming a spacer region (18), and at least one region edge has a profile geometry (16) in its axial direction, which has a varying edge distance relative to the adjacent connecting portion, wherein the profile geometry has a profile depth (t) in the circumferential direction, the profile depth being a multiple of the diameter of the through holes.

Description

Technical Field

[0001] This invention relates to a filter screen, a tubular filter, a filtration device, and a manufacturing method thereof. Background Technology

[0002] DE 10 2017 212 944 A1 discloses a cylindrical steam screen for a quick-closing valve in a steam turbine, wherein multiple perforated individual screen segments, formed by selective laser melting, are loosely arranged in an overlapping manner along the circumference and fixed with screws by support rings on the end face side. The perforated areas of the screen elements each have a straight, axially extending edge in the circumferential direction.

[0003] KR 102564334 B1, KR 100992097 B1, and KR 100988217 B1 each relate to a tubular filter for a plate heat exchanger, wherein a perforated cylindrical filter sleeve is fixed to an inner spiral filter carrier by welding, or its circumferential side edges overlap and are fixed by an inner clamp, or multiple circumferential side edges are spaced apart and movably connected by elastic connectors inserted into the gaps. The perforated areas with through holes each have a straight, axially extending edge in the circumferential direction.

[0004] WO97 / 26973A1 discloses a filtration device, a tubular filter element, a filter screen, and a scraper arranged on the filter screen for removing filter residue from the filter screen. The filter screen is formed by circularly bending a flat (flachen) screen blank or screen plate and has a screen wall with perforated areas consisting of densely arranged, laser-drilled fine through-holes. The screen plate or screen wall forms a hollow cylinder with a circular cross-section (so-called a hollow cylinder), which in practice is achieved by an axial weld. The perforated areas extend circumferentially to both sides of the weld. The filter screen and its screen wall have mechanical weak points in the weld area and adjacent perforated areas. Summary of the Invention

[0005] The purpose of this invention is to provide a filter screen technology that improves mechanical stability.

[0006] This invention achieves this objective using the technical solution according to the invention.

[0007] The aforementioned filter screen technology (i.e., filter screens, screen blanks, tubular filters, filtration devices, methods for manufacturing filter screens, and applications of filter screens, tubular filters, and filtration devices in producing filtered liquids, particularly plastic melts) offers numerous advantages. The durability, mechanical stability, and efficiency of filter screens, tubular filters equipped with filter screens, and filtration devices are all improved. This also enables the achievement of high and stable quality of the filtered liquid, particularly the plastic melt, and avoids or at least reduces wear during the filtration process.

[0008] The filter screen according to the invention has the following advantages: the edge of the perforated region, extending axially and circumferentially, terminates at a distance in front of the connection point (Verbindungsstelle, connection position) when viewed circumferentially. Thus, the perforated region and the densely arranged fine through-holes therein are spaced circumferentially from the connection (e.g., weld). The spacer region can be constructed differently from the perforated region. For example, it can be constructed as solid. Furthermore, at least one region edge can have a contour geometry in its axial direction, with a varying edge distance to the adjacent connection. The contoured region edge also has another directional component in its direction, transverse to the axial direction, particularly in the circumferential direction, through its varying edge distance.

[0009] The spacing and profile geometry of the filter screen have a favorable impact on its high mechanical load-bearing capacity and durability. During operation, the curved screen walls of the filter screen maintain shape and dimension stability throughout the entire circumference, including the connection areas. This is also advantageous for the efficient and low-load removal of filter residues, particularly scraping. The connections and curved screen walls can transition smoothly and flush with each other, at least at the screen walls where the liquid, especially the molten plastic, flows. Thus, they do not hinder the removal of filter residues, especially scraping, and reduce wear. High dimensional stability advantageously contributes to uniform and long-term high filtration quality. This is particularly advantageous for liquids, especially viscous liquids when necessary, particularly molten plastic.

[0010] The filter screen for which protection is sought can be manufactured using the method for which protection is sought. The filter screen can be a standalone product. It can be present on the tubular filter and filtration unit at initial installation. It can also be added to or retrofitted to the tubular filter and filtration unit, especially to replace another existing filter screen.

[0011] Filter screens, tubular filters, and filtration devices are designed for filtering liquids, particularly molten plastics. Filter screens, tubular filters, and filtration devices can be used to produce filtered liquids, particularly molten plastics.

[0012] The perforated area and its densely packed fine pores can be adjusted in size, structure and arrangement according to the different characteristics of the liquid to be filtered, especially the plastic melt, when necessary.

[0013] The filter screen is preferably bent from a flat screen blank, particularly into a circular shape, preferably a rounded shape. Its circumferentially oriented edges, with their axially oriented components, are preferably joined together at the connection point or so-called joint by a butt joint, and can be securely connected to each other through the joint. Other materials with axially oriented components, such as adhesive joints, can also be used instead of welds for the joint.

[0014] The axial orientation mentioned in the claims and hereinafter refers to the filter axis of a curved filter screen or tubular filter. This can be, for example, the central axis of a preferably hollow cylindrical filter screen. The filter screen can also have other tubular forms, such as a hollow truncated cone. The preferred circular cross-section can also vary. For example, a hollow cylinder is advantageous for a filter screen that rotates about the filter axis. A stationary filter screen can also have other cross-sectional shapes, such as elliptical or prismatic. The screen blank can be bent in different ways accordingly.

[0015] The axial direction component of the connecting part and / or the edge of the region and / or the edge of the blank can have a precise axial orientation. Another superimposed directional component may also exist, such as a circumferential directional component. Thus, oblique or helical extensions can be produced, for example.

[0016] The profile geometry can have different designs. It can, for example, have at least one protrusion facing the connection. Alternatively or additionally, it can have at least one recess facing away from the connection. The protrusion and / or recess can exist individually or in multiples. In the regions of the protrusion and / or recess, the profiled region edge can have another and different directional component superimposed on the axial component, particularly in the circumferential direction. In the regions of the protrusion and / or recess, the region edge can extend laterally or obliquely towards the filter axis. This improves the mechanical strength of the region.

[0017] In an advantageous implementation, there are multiple protrusions and multiple recesses, which alternate with each other, for example, in a direct sequence or other manner. A cycle may exist here. A protrusion may be followed directly by a recess, and so on. As a variation, in another alternating sequence, for example, two or more protrusions may appear consecutively, followed by one or more recesses, and so on.

[0018] One or more protrusions and one or more depressions may point toward the connecting part or away from the connecting part along the circumference of the filter screen, respectively.

[0019] In an advantageous embodiment, a plurality of through holes may be arranged successively and side-by-side circumferentially in the protrusions pointing towards the connecting portion at the edge of the region. In the recessed region facing away from the connecting portion, the through holes may be absent. Here, the screen wall may, for example, be constructed as solid. The spacing region may extend into the recess.

[0020] In an advantageous embodiment, the profile geometry is specified to have a profile depth (t) when viewed circumferentially, which is a multiple of the through-hole diameter. The profile depth (t) can refer to the direction extending transversely to the axial direction of the region edge, particularly the circumferential direction. The profile depth (t) can, for example, involve the distance between the vertices of one or more protrusions and one or more recesses in the circumferential direction. This can also be understood as the magnitude of the lateral offset of the profiled region edge relative to its axial extension.

[0021] Therefore, the outlined edge of the perforated area can vary significantly relative to its axial extension, especially with lateral or oblique offsets.

[0022] A distinctive profile geometry has proven to be particularly advantageous for the durability of filter screens.

[0023] The contour geometry may exist only on one or two circumferential edges of the perforated region. The perforated region itself may exist continuously between the edges of the region. Alternatively, the perforated region may also have one or more interruptions, which may be formed, for example, by substantially solid areas of the screen wall. The perforated region may extend axially to the curved edge of the filter screen, or may terminate at a distance in front of it on one or both sides. In the interstitial regions, the screen wall may again be constructed to be solid.

[0024] There are various possibilities for the shape design of the contour geometry. For example, the contour geometry can be wavy, with multiple protrusions pointing towards adjacent connections and multiple recesses facing away from the connections. The wavy shape can be meandering.

[0025] The wavy pattern can be, for example, uniformly formed. This can mean that the protrusions and recesses have the same configuration and / or the same size. Furthermore, a period can exist in the alternating arrangement of protrusions and recesses. Alternatively, the wavy pattern can be non-uniform, where, for example, the protrusions and recesses can have different sizes and, if necessary, different shapes.

[0026] The contour geometry may include rounded or angular protrusions and / or recesses (one or more). A mixture of rounded and angular shapes is also possible. Angular structures may be, for example, arrowhead-shaped, triangular, or dovetail-shaped rectangles. In particular, the contour geometry of the region edge may also have only a single, preferably rounded, protrusion or only a single, preferably rounded, recess. Such a single protrusion or recess may extend over the entire length of the relevant region edge.

[0027] Furthermore, the contour geometry of the region's edge may include one or more axially oriented, straight segments in its orientation. Protrusions and adjacent recesses may transition directly to each other. They may also be axially spaced apart and connected, for example, by straight, axially oriented segments of the contour geometry. Another possible design for a wavy shape may include only protrusions or only recesses, each with an axially oriented, straight segment in between.

[0028] Furthermore, protrusions and recesses can alternate in any manner, especially when inserting potentially straight and axially oriented segments of the contour geometry. In short, the contour geometry can have a wide variety of designs. Other variations are also possible besides the examples mentioned above.

[0029] At least one of the interval regions between the edge and the connecting portion can be constructed as solid. This solid construction can also surround smaller perforations and / or groove-shaped recesses on the screen wall in the interval region.

[0030] In one advantageous embodiment, the screen wall may have a thickness between 1.0 mm and 2.0 mm.

[0031] The through holes in the perforated area and the sieve wall can each have a diameter between 30 µm and 1500 µm. Preferably, the diameter is between 60 µm and 1000 µm.

[0032] Through holes can have any cross-sectional shape, such as circular or prismatic. Through holes can be constructed to be the same or different from each other.

[0033] Through holes can be arranged in any manner within the perforated region. They can be separated from each other by screen wall strips. Through holes can be arranged, for example, in multiple rows and columns, such as in a regular, preferably rectangular matrix. Adjacent rows or columns of through holes can also be staggered. The filling density of the through holes can be the same throughout the perforated region. Furthermore, the through holes may have an irregular distribution and different filling densities; the filling density may be variable or locally variable.

[0034] Through-holes penetrate the screen wall. Their shape and orientation can vary. They can, for example, have the same cross-sectional shape along their length or be conical. The through-holes can be oriented orthogonally to the screen wall surface. In curved, particularly hollow cylindrical, filter screens, they can be oriented radially relative to the filter axis. Alternatively, one or more through-holes can also have an oblique orientation.

[0035] In an advantageous embodiment, the connection point and connection portion can have a straight, axially oriented line. This can deviate from a precise axial orientation. The connection point and connection portion can also have another directional component, for example, circumferentially oriented. Thus, the connection point and connection portion can have, for example, a helical orientation. The connection portion can have a continuous line. It can also have a discontinuous line. Furthermore, other configurations of the connection point and connection portion are also feasible. Welds can be replaced by connections made of other materials, such as adhesive joints.

[0036] The screen wall can be formed from a flat, flexible metal plate. The screen wall or metal plate can have the aforementioned flat shape. The wide sides can be oriented parallel to each other. The material of the metal plate is optional. It can be matched to the requirements of the fluid to be filtered. The metal plate can be made of, for example, steel, especially stainless steel, brass, or similar materials.

[0037] Through-holes in the sieve wall can be formed using a beam technique. Alternatively, other techniques can be used to introduce through-holes, such as cutting, drilling, stamping, and etching.

[0038] In an advantageous embodiment of the filter screen, the edges of the curved screen blank can be circumferentially butted together at a connecting portion. These blank edges form the circumferential edges of the screen wall. The connecting point and the connecting portion can be located here.

[0039] The present invention also includes a screen blank. This screen blank can be designed to form the screen wall of a curved filter screen for a tubular filter. The screen blank can be constructed to be flat and flexible, and can have the perforated areas with through holes and area edges. This screen blank can be constructed according to the aforementioned embodiments of filter screens and their screen walls.

[0040] In the screen blank, the edges of the perforated areas can terminate at a certain distance in front of adjacent blank edges. These blank edges are then oriented in the axial direction component when the screen blank is bent into a filter screen. For the screen blank, the blank edges can be formed, for example, by the transverse edges of an elongated screen blank. Other blank edges, for example, oriented transversely to the area edges, can be the longitudinal edges of the screen blank. In a bent screen filter, they can form corresponding end-rounded screen edges.

[0041] The screen blank can be constructed as a preferably flat, rectangular, flat, and flexible metal plate. It can have the aforementioned type of construction. Furthermore, the screen blank can have the aforementioned embodiments regarding the screen wall, such as the thickness, the diameter of the through holes, etc.

[0042] The present invention also includes the aforementioned tubular filter. This tubular filter can also be a standalone product and can be used for the initial installation, addition, or retrofitting of a filtration device. The tubular filter is equipped with, for example, a hollow cylindrical filter screen and the aforementioned design. The tubular filter may also have multiple of the aforementioned filter screens. Furthermore, the tubular filter may include, for example, a hollow cylindrical filter carrier on which the filter screen is arranged. This arrangement is preferably circumferential, particularly on the outer side of, for example, the cylindrical filter carrier. The filter carrier may be permeable to the liquid to be filtered, particularly molten plastic. The filter screen can be replaceably and removably arranged and secured to the filter carrier.

[0043] In one advantageous embodiment, the filter carrier can be configured as a rotatable filter shaft. The filter screen can be arranged on the rotatable filter shaft and rotated therethrough during filtration operation. The filter carrier and filter screen can be rotated in a controlled manner. They can have a consistent, preferably centered, filter axis.

[0044] The invention also includes the aforementioned filtration device. This filtration device is equipped with a tubular, particularly hollow cylindrical, filter screen, which can be constructed in the manner described above. Similarly, a tubular filter can also be constructed in the manner described above.

[0045] The filter device may have a scraper for filtering residue. The scraper may be arranged on the outside or inside the circumference of the tubular filter screen. The scraper may be oriented, for example, axially with its line of action, particularly parallel to the filter axis. Alternatively, it may also have an oblique orientation, or if necessary, a helical orientation. The scraper may be arranged statically or movable and adjustable. Furthermore, the filter device may have a discharge device that works in conjunction with the scraper for discharging the scraped filter residue. This device can discharge the filter residue intermittently and quantitatively.

[0046] Furthermore, the filtration device may have a filter chamber with an inlet and an outlet for the liquid to be filtered, particularly molten plastic. A filter screen may be arranged statically or movablely, particularly driven by rotation, within the filter chamber and connected to the inlet and outlet. The liquid to be filtered, particularly molten plastic, flows through the filter screen from the outside in, wherein the filter screen, and, if necessary, the internal cavity of the filter carrier, is connected to the outlet. This connection can also be reversed.

[0047] The present invention also includes a method for manufacturing the claimed filter screen. The invention further relates to the application of the claimed filter screen in the manufacture of filtered liquids, particularly plastic melts. The application may also relate to tubular filters and / or filtration devices.

[0048] Further advantageous embodiments of the present invention will be described below.

[0049] The device features of the described and claimed filter screens, tubular filters, screen blanks, and filtering devices can be advantageously used in the claimed method. Conversely, the feature features of the described and claimed method can also be advantageously used in the claimed device. Therefore, the method features and device features are interchangeable.

[0050] The filter screen, screen blank, tubular filter and filtration device of the claimed device, as well as the method of the claimed protection, may each include the following additional features, which can be used individually or in any combination.

[0051] The perforated area may have a contour geometry, which preferably has a uniform, particularly tortuous, wavy shape.

[0052] The perforated area may have a contour geometry with one or more protrusions and / or one or more recesses, which may have rounded and / or angular shapes, respectively.

[0053] The gap between the edge of the perforated area and the connecting part, as well as the gap between the connecting points, can be constructed to be solid.

[0054] Through holes in the perforated area can be formed using jetting technology.

[0055] The connecting parts can have straight and axially oriented lines. The connection points can also have this type of line.

[0056] The screen wall of a filter screen can be formed from the screen blank.

[0057] The screen blank can be bent into a preferred circular shape, especially a round shape, and then a connecting part, especially a weld, can be provided at the connection point.

[0058] Preferably, the circumferentially oriented edges of the circularly curved, especially roundly curved, screen blank can be joined together at preferably straight connection points and connected to the joint, especially the weld.

[0059] The edges of the perforated areas can each end at a certain distance before the edges of adjacent blanks in the screen blank, especially the transverse edges.

[0060] The filter carrier of a tubular filter can be constructed as a rotatable filter shaft.

[0061] The filtration device may have a discharge device for scraping off filter residue, which works in conjunction with a scraper.

[0062] The filtration device may have a filter chamber with an inlet and an outlet for the liquid to be filtered, particularly molten plastic. A filter screen may be fixedly or movably, particularly rotary-driven, arranged within the filter chamber and connected to the inlet and outlet.

[0063] When producing filtered liquids, particularly plastic melts, using the required protected filter screen, the original liquid, particularly the plastic melt, from which particles can be filtered, can be supplied to the filter screen and discharged from it as filtered liquid, particularly the plastic melt, after flowing through the filter screen. The filtered particles, which deposit as filter residue on the filter screen, can be detached from the filter screen, particularly scraped off, and discharged. Attached Figure Description

[0064] The present invention is illustrated in the accompanying drawings by way of example and illustration. Wherein: Figure 1 The filter screen is shown in perspective view. Figure 2 The diagram shows a partial enlarged view of the screen wall and the screen blank at the connection point, including the perforated area with a connecting portion and a contoured circumferential region edge. Figure 3 A magnified detail view of the outline geometry of the area edge at the connection point is shown. Figures 4 to 8 Different design variations of the contour geometry of the perforated area's edge are shown. Figure 9 Partial cross-sectional views of the screen wall or screen blank and different design variations of the through holes in the perforated area are shown. Figure 10 The top view shows the process of forming Figure 1 The screen blank for the filter screen, Figure 10a It shows Figure 10 A flipped side view of the screen blank. Figure 11 A cross-sectional side view of a filtration device with a tubular filter and a filter screen is shown, as well as Figure 12 It shows according to Figure 11 The cross-section of the filter device along section line XII-XII.

[0065] List of reference numerals in the attached diagram: 1: Filtration device 2: Filters, tubular filters 3: Filter axis 4: Filter screen 5: Filter carrier, filter shaft 6: Filter chamber 7: Inlet 8: Outlet 9: Scraper 10: Discharge device 11: Screen wall 12: Screen edge 13: Perforated area 14: Through hole 15: The edge of the perforated area 16: Outline Geometry 16': Protrusion 16": Depression 17: Connection, weld 17': Connection point, joint point 18: Interval area 19: Screen blank 20: Edge of billet 21: Horizontal edge 22: Vertical edge 23: Metal plate 24: Filtered liquids and plastic melts 24': Original liquid, plastic melt 25: Filter residue a1: Distance a2: Distance t: Contour depth Detailed Implementation

[0066] The present invention relates to filter screens (4), screen blanks (19), tubular filters (2), filtration devices (1), methods for manufacturing filter screens (4), and applications of using filter screens (4) to manufacture filtered liquids, particularly plastic melts (24).

[0067] Figure 1 A perspective view shows a tubular, for example, hollow cylindrical filter screen (4). The filter screen (4) is formed by bending a flat screen blank (19) preferably circularly, especially rounded, and has a filter axis and a screen wall (11). The bent screen wall (11) has a perforated area (13) on its circumference, which has densely arranged fine through holes (14).

[0068] A connecting portion (17) oriented in the axial direction is also provided on the circumference. Through this connecting portion, the edges of the circumferentially mated screen walls (11), and especially the blank edges (20) of the screen blanks (19), are firmly connected to each other. The connecting portion (17) is constructed, for example, as a weld. In an embodiment, it has a straight orientation about the filter axis (3). Alternatively, the preferably linear connecting portion (17) may also have other extensions, such as a spiral shape. Figure 1 In the diagram, for clarity, only the through holes (14) of the perforated area (13) are shown on the outer side of the sieve wall (11). They are also schematic and are enlarged for better identification.

[0069] according to Figure 1 The perforated region (13) has a region edge (15) at each of its two ends along the circumferential direction, and the region edge extends in a manner having an axial component. The region edges (15) terminate circumferentially at a certain distance in front of the connecting part (17). Thus, a spacer region (18) is formed on the screen wall (11). There are no through holes (14) of the perforated region (13) in this spacer region (18). The spacer region (18) is constructed, for example, as a solid. However, it may also have isolated through holes or groove-shaped recesses.

[0070] At least one region edge (15) has a profile geometry (16) along its axial direction, the profile geometry having varying edge distances (a1, a2) from the region edge (15) to the adjacent connection (17). Figure 3 Details of the circumferentially pointing edge distances (a1, a2) are shown.

[0071] The outline geometry (16) can have different designs. Figures 2 to 8 Various variations are shown for this purpose. Figures 2 to 8In the middle, the contour geometry (16) has multiple protrusions (16') pointing towards the connecting portion (17) and multiple recesses (16") facing away from the connecting portion (17). Multiple through holes (14) are arranged in the protrusions (16') pointing towards the connecting portion (17) along the circumferential direction. Here, according to Figure 1-8 Multiple through holes (14) are arranged sequentially and side by side in the circumferential direction.

[0072] like Figure 3 As shown, the contour geometry (16) has a contour depth (t) that is a multiple of the diameter of the through hole (14). The contour depth (t) points circumferentially to the filter screen (4) and, in the illustrated embodiment, represents the distance between the apex of the protrusion (16') and the recess (16"). The spacer region (18) extends into the recess (16").

[0073] The contour geometry (16) has, for example, Figures 1 to 8 The wavy shape shown has a plurality of protrusions (16') pointing circumferentially toward the connector (17) and a plurality of recesses (16") pointing away from the connector (17). Here, the protrusions (16') and recesses (16") alternate with each other, for example, in a direct order. The configuration and size of the protrusions (16') and recesses (16") are, for example, identical to each other. These embodiments describe a preferred uniform wavy shape of the profile geometry (16). Alternatively, other and non-uniform embodiments of the profile geometry (16) different from those described above are also possible.

[0074] exist Figures 1 to 6 In one embodiment, the contour geometry (16) has angular protrusions (16') and recesses (16"), respectively. These are in Figure 2 , Figure 5 and Figure 6 The design is either sharp, arrow-shaped, or triangular. Figure 4 The diagram shows a stacked profile geometry with rectangular protrusions (16') and recesses (16"). Figure 7 and Figure 8 A variation with a rounded protrusion (16') and recess (16") configuration is shown. As shown, the number and size of the sequentially arranged protrusions (16') and recesses (16") can also vary.

[0075] also, Figure 8A variation of the contour geometry (16) is also shown in dashed lines, which has only a preferred rounded protrusion (16') and / or only a preferred rounded recess (16"). Here, for example, the two region edges (15) may each have a single protrusion (16') or a single recess (16") respectively. The aforementioned variable edge distances (a1, a2) and the contour depth (t) of the contour geometry (16) can also be generated here, for example, as the magnitude of the lateral offset of the shaped region edge (15) with its axial extension as a single protrusion (16') or recess (16").

[0076] Figure 9 An exemplary portion of the screen wall (11) or screen blank (19) is shown, wherein the through holes (14) have different design options. The through holes (14) are oriented, for example, orthogonal to the outside of the screen wall (11) or screen blank (19). In a curved filter screen (4), they are oriented radially, for example, relative to the filter axis (3).

[0077] The through-hole (14) shown in the left half of the figure has a constant cross-section along its length. The opening shape can be cylindrical. Another through-hole (14) shown is, for example, conical, which can, for example, taper towards the outside of the screen wall (11). The outside can, for example, be the inlet side during filtration.

[0078] The through hole (14) may have a cross-sectional shape, for example, a perfect circle. The cross-sectional geometry may remain constant along the length of the through hole (14), or it may vary. Alternatively, other cross-sectional shapes may be used, such as elliptical, prismatic, etc.

[0079] The screen blank (19) and the screen wall (11) formed therefrom can advantageously have a thickness between 1.0 mm and 2.0 mm.

[0080] The through-hole (14) may, for example, have a diameter between 30 µm and 1500 µm. Preferably, the diameter is between 60 µm and 1000 µm.

[0081] Through holes (14) are formed in the screen blank (19) or screen wall (11) by beam technology, for example by beam drilling.

[0082] Figure 10 and Figure 10a The top view and the flipped side view show a flat and flat screen blank (19) having a preferred cuboid shape, which is then formed from the screen blank by a preferably circular, particularly rounded, bending process. Figure 1 , Figure 11 and Figure 12The filter screen (4) and its preferably cylindrical screen wall (11) are shown. Here, at the connection point (17') or at the connection part (17), the preferably straight blank edge (20) of the curved screen blank (19) is circumferentially joined. Figure 1 and Figure 2 The butt joint, connection point (17'), and connection portion (17) therein, particularly the weld, are shown. The blank edges (20) have, for example, a flat shape and abut each other flatly, for example, in preferred full contact, wherein the connection portion (17), for example the weld, is then located at the connection point (17').

[0083] In the illustrated embodiment, the connecting portion (17) has a straight and axially oriented line. Alternatively, the connecting portion (17) may also have a deviated axial direction, such as a spiral. The connecting point (17') may have a corresponding line and a corresponding direction. Similarly, in the illustrated embodiment, one or two region edges (15) also have a generally axial orientation. The lines connecting the vertices of the protrusions (16') and the vertices of the recesses (16") also have a straight and axial orientation. In variations relative to this, a strict axial orientation may also be deviated from. Another and different directional component, particularly the circumferential directional component, may be superimposed on the axial component. This can thus form, for example, a spiral orientation of the region edges (15) and their contour geometry (16).

[0084] The screen blank (19) and the screen wall (11) formed by the curved screen blank (19) are respectively made of a flat, flat and flexible metal plate (23). The metal can be, for example, stainless steel or brass or other metals.

[0085] The screen blank (19) has, for example, Figure 10 and Figure 10a The shape shown is elongated and rectangular in the top and side views. It has a longitudinal edge (22) and a short transverse edge (21). For example, to form a filter screen (4), the screen blank (19) is formed, for example, along the longitudinal edge (22) and... Figure 10 The filter and bending axis (3) shown is bent. The transverse edge (21) forms, for example, a blank edge (20) located circumferentially and butt-jointed at the connection point (17') in the case of a bent screen wall (11). The longitudinal edge (22) forms the end face side screen edge (12) of the filter screen (4). In other embodiments, the screen blank (19) may have other shapes, such as square or rhomboid. If necessary, it may also be bent on a shorter transverse edge (21).

[0086] like Figure 1 and Figure 10As shown, the perforated area (13) may extend axially to one or both longitudinal edges (22) or to the end face side screen edge (12) formed by the longitudinal edges on the curved filter screen (4). Alternatively, the perforated area (13) may terminate at one or both longitudinal edges (22) or at a certain axial distance in front of the screen edge (12).

[0087] exist Figure 10 The through holes (14) are also shown schematically and enlarged for better identification. The shape and distribution of the through holes (14) shown here are exemplary, for example, in a regular and rectangular matrix form, wherein the through holes (14) are arranged in multiple rows and columns. Alternatively, adjacent rows of through holes (14) may also be arranged in a staggered manner. In addition, through holes (14) may also be arranged and distributed in any other form in the perforated area (13).

[0088] Figure 11 and Figure 12 A filtration device (1) is shown, comprising a tubular filter (2) and filter screens (4) arranged on the tubular filter, as well as a filter shaft (3), a scraper (9), and a discharge device (10). One or more filter screens (4) are arranged, for example, on the outer periphery of a cylindrical filter carrier (5). The filter carrier (5) may have, for example, the following features: Figure 12 The cross-section shows the permeable form of the liquid to be filtered, particularly the plastic melt (24, 24'). The filter carrier (5) is designed, for example, as a hollow body with multiple radial holes extending into the outer filter screen (4), which lead to a central borehole.

[0089] The filtration device (1) includes, for example, a housing in which a filter chamber (6) is formed, and an inlet (7) for the raw liquid containing particles to be filtered, particularly molten plastic (24'), is opened to the filter chamber, for example, on the circumferential side. A filter carrier (5) and a filter screen (4) are arranged in the filter chamber (6). The supplied raw liquid containing particles, particularly molten plastic (24'), flows through the filter screen (4) and its perforated area (13) with through-holes (14), wherein particles are filtered out and deposited on the filter screen (4) as filter residue (25). Subsequently, the filtered liquid, particularly molten plastic (24'), is discharged from the filter screen (4).

[0090] The filter carrier (5) is configured, for example, as a rotatable filter shaft, which can preferably be controllably rotated by a drive not shown. The outlet (8) for the filtered liquid, especially the plastic melt (24), can be drawn out from the internal space of the hollow cylindrical filter screen (4) and the filter carrier (5). It can be drawn outward, for example, through the shaft extension of the filter shaft.

[0091] In the diagram shown, the filter screen (4) is flowed from the outside in. Alternatively, the reverse arrangement is also possible, in which the filter screen (4) is flowed from the inside out by the raw liquid to be filtered, particularly the plastic melt (24'), where the inlet (7) extends into the hollow interior space of the filter screen (4) and the filter carrier (5), and the outlet (8) is led outward on the filter housing. Figure 11 The possibility of sealing the filter housing and the filter chamber (6) constructed therein with a removable cover on the end face side is also shown. Thus, the filter screen (4) can be replaced as needed.

[0092] A scraper (9), designed as, for example, blade-shaped, acts on the outer periphery of the filter screen (4) in the illustrated embodiment and scrapes off the filter residue (25) adhering thereto as the filter rotates. The scraper (9) is, for example, fixedly arranged. It is oriented with its working side, particularly the scraper blade axially and parallel to the filter axis (3). A preferably controllable discharge device (10) is also arranged in the area of ​​the scraper (9) to continuously or intermittently discharge the filter residue (25) scraped off and collected at the scraper (9). The discharge device (10) includes, for example, a screw-shaped conveying shaft that extends parallel to the filter axis and the axis of rotation (3) and axially conveys the filter residue (25) by rotation. Here, it can be inserted into a discharge space at the end of the screw, in which quantitative lateral discharge can be achieved at the journal by a radial receiving channel and a push rod arranged there and oscillating. The scraper (9) and the discharge device (10) can be constructed, for example, according to WO2022 / 135855A1.

[0093] There are many possible variations of the embodiments shown and described.

[0094] The filter screen (4), tubular filter (2), and filter device (1) shown in the accompanying drawings, as well as the screen blank (19), can be modified in the manner mentioned in the introduction of the specification. The features of these embodiments and modifications can also be interchanged within the scope of the claims.

Claims

1. A filter screen for a tubular filter (2), designed for filtering liquids, wherein, The filter screen (4) is tubular and is formed by bending a flat screen blank (19). The filter screen (4) has: a filter axis (3); a screen wall (11) and a perforated area (13) on the circumference of the screen wall (11), the perforated area having densely arranged, fine through holes (14); and a connecting portion (17) oriented in the axial direction. The perforated area (13) has a region edge (15) extending in the axial direction at both ends along the circumferential direction, wherein the region edge (15) terminates at a certain distance in front of the connecting portion (17) when forming a spacer area (18), and at least one of the region edges (15) has a contour geometry (16) in its axial direction, the contour geometry having a varying edge distance (a1, a2) relative to the adjacent connecting portion (17), wherein the contour geometry (16) has a contour depth (t) in the circumferential direction, the contour depth being a multiple of the diameter of the through hole (14).

2. The filter screen according to claim 1, characterized in that, The contour geometry (16) has at least one protrusion (16') pointing toward the connection (17) and / or at least one recess (16") facing away from the connection (17).

3. The filter screen according to claim 1 or 2, characterized in that, In the protrusion (16') pointing to the connecting part (17), a plurality of through holes (14) are arranged sequentially and side by side in the circumferential direction.

4. The filter screen according to claim 1 or 2, characterized in that, The contour geometry (16) has a uniform, meandering wave shape with a plurality of protrusions (16') pointing toward the connection (17) and a plurality of recesses (16") facing away from the connection (17), wherein the contour geometry (16) has rounded and / or angular protrusions (16') and / or recesses (16"), and wherein the gap region (18) between the edge of the region (15) and the connection (17) is constructed to be solid.

5. The filter screen according to claim 1 or 2, characterized in that, The sieve wall (11) has a thickness between 1.0 mm and 2.0 mm, and the through holes (14) have a diameter between 30 µm and 1500 µm.

6. The filter screen according to claim 5, characterized in that, The through holes (14) each have a diameter between 60 µm and 1000 µm.

7. The filter screen according to claim 1 or 2, characterized in that, The screen wall (11) is constructed of a flat, flexible metal plate (23).

8. The filter screen according to claim 1 or 2, characterized in that, The straight blank edge (20) of the curved screen blank (19) is joined circumferentially at the connection (17).

9. The filter screen according to claim 1 or 2, characterized in that, The filter screen (4) is designed to filter plastic melt (24), and / or the filter screen (4) has a hollow cylindrical shape, and / or the connection (17) is constructed as a weld.

10. A screen blank designed to form the screen wall (11) of a curved filter screen (4) for a tubular filter (2), characterized in that, The screen blank (19) configured as flat and flexible has perforated regions (13) with through holes (14) and region edges (15), said perforated regions being configured according to any one of claims 1 to 9.

11. The screen blank according to claim 10, characterized in that, The screen blank (19) is constructed as a rectangular, flat, flexible metal plate (23).

12. A tubular filter designed for filtering liquids (24), the tubular filter having a filter screen (4), characterized in that, The filter screen (4) is constructed according to any one of claims 1 to 9.

13. The tubular filter according to claim 12, characterized in that, The tubular filter (2) includes a filter carrier (5), wherein the filter screen (4) is preferably arranged circumferentially on the filter carrier, and wherein the filter carrier (5) is configured as a rotatable filter shaft.

14. A filtration device designed for filtering a liquid (24), wherein the filtration device (1) has a tubular filter (2) having a tubular filter screen (4), characterized in that, The filter screen (4) is constructed according to any one of claims 1 to 9, and the tubular filter (2) is constructed according to claim 12 or 13.

15. The filtration device according to claim 14, characterized in that, The filter device (1) has a scraper (9) for filtering residue (25), the scraper being arranged on the outside or inside of the circumference of the tubular filter screen (4), and the filter device (1) has a discharge device (10) that works in conjunction with the scraper (9) for discharging the scraped filter residue (25).

16. The filtration device according to claim 14 or 15, characterized in that, The filter device (1) is designed to filter plastic melt, and / or the tubular filter (2) has a hollow cylindrical filter screen (4).

17. A method for manufacturing a filter screen (4) for a tubular filter (2), the filter screen being designed for filtering a liquid (24), wherein the filter screen (4) is tubular, the filter screen (4) being formed by bending a flat screen blank (19), wherein the filter screen (4) has a filter axis (3) and a screen wall (11) formed from the screen blank (19), and wherein the screen wall (11) has a perforated area (13) with densely arranged, fine through holes (14) on its circumference and a connecting portion (17) oriented in an axial direction component, characterized in that, The perforated area (13) is formed in the flat screen blank (19) and terminates circumferentially at a certain distance in front of the connecting part (17) in the case of forming the interval area (18). The edges (15) of the areas of the perforated area (13) adjacent to the connecting part (17) have contour geometry (16) in their axial direction. The contour geometry has an edge distance (a1, a2) that varies relative to the connecting part (17). The contour geometry (16) has a contour depth (t) when viewed in the circumferential direction. The contour depth is a multiple of the diameter of the through hole (14).

18. The method according to claim 17, characterized in that, The liquid is a plastic melt, and / or the filter screen (4) has a hollow cylindrical shape, and / or the connection (17) is a weld.

19. A method for producing a filtered liquid (24), the method using a filter screen (4) according to any one of claims 1 to 9, wherein, The raw liquid (24') containing filterable particles is supplied to the filter screen (4) and discharged from the filter screen (4) as filtered liquid (24) after flowing through the filter screen (4).

20. The method according to claim 19, characterized in that, The liquid is a plastic melt.

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