METHOD FOR MANUFACTURING SCREEN BODY, AND SCREEN

Abstract

The present invention relates to a method for manufacturing a screen body having one or more openings (18) in a screen surface (5), in particular a screen body for a screen (1) to be used in a screw press (10). To achieve a particularly long service life, the present invention provides for the screen body to be formed by sintering and / or additive manufacturing, in particular by 3D printing. The present invention further relates to a screen (1), in particular a screen (1) for a screw press (10), having a screen body having one or more openings (18) in a screen surface (5).

Description

[Technical field]

[0001] The present invention relates to a method for manufacturing a screen body having one or more openings in the screen surface, in particular for a screen to be used in a screw press.

[0002] The present invention further relates to a screen, in particular a screen for a screw press, having a screen body with one or more openings in the screen surface. [Background technology]

[0003] Screw presses are well known from the prior art. Such screw presses are used, for example, for separating liquids from a material to be conveyed and have a conveying helix spirally arranged on a driven screw shaft and a housing mantle surrounding it, with a conveying passage for the material to be conveyed being formed between the screw shaft and the housing mantle, which is partially delimited by the conveying helix in order to convey the material through the conveying passage along the longitudinal axis of the screw press by the conveying helix when the screw shaft rotates. The housing mantle then usually has openings, so that the liquid is separated from the material to be conveyed through the pressure exerted on it when the material is conveyed and conveyed out of the conveying passage through the openings to dry the material during its movement through the screw press along the longitudinal axis. The openings are usually made in a thin plate acting as a screen, which is part of the housing mantle. Such a screen is produced in the prior art by drilling holes in the thin plate. Since the thin plate has a cylindrical contour, this is associated with high costs.

[0004] The function of the screw press depends on the friction between the material to be transferred and the screw shaft or the conveying helix arranged on the screw shaft, on the one hand, and on the friction between the material to be transferred and the inner surface of the housing mantle, i.e. a screen which is usually configured as a thin plate against which the screw shaft is driven in rotation during operation. If the friction between the material to be transferred and the inner surface of the housing mantle falls below a defined threshold value, when the screw shaft rotates, the material to be transferred is not conveyed along the longitudinal direction of the screw shaft, but only moves in rotation relative to the housing mantle around its longitudinal axis, including the screw shaft and the conveying helix, so that drying of the material to be transferred does not take place and the corresponding process comes to a halt.

[0005] In the prior art, the housing mantle usually has a metal screen with a defined minimum roughness when installed in a new state in order to ensure a suitable friction between the transported material and the housing mantle. However, it has been shown that during operation, the continuous sliding of the transported material, which may be made of cellulose for example, along the metal screen leads to wear of the screen, which in turn leads to a reduction in the roughness of the metal screen. Thus, the operation of the screw press, due to the surface wear of the metal screen over a long period of time, leads to malfunctions of the screw press caused by too little friction. Summary of the Invention [Problem to be solved by the invention]

[0006] The present invention addresses this issue. It is an object of the present invention to provide a method for producing a screen body of the type mentioned at the beginning, which, when used in a housing casing of a screw press, allows the screw press to function over a particularly long period of time and at the same time is easy to produce.

[0007] It is further intended to provide a screen of the type mentioned at the outset which, when used in a housing mantle of a screw press, enables the functioning of the screw press over particularly long periods of time. [Means for solving the problem]

[0008] The first problem is solved according to the invention by a method of the type mentioned at the beginning, in which the screen body is produced by sintering and / or additive manufacturing methods, in particular by 3D printing methods.

[0009] Within the scope of the present invention, it has been found that materials formed by sintering and / or by additive manufacturing methods, in particular 3D printing, have a certain surface roughness, and this holds true even if parts of the surface are removed, for example due to wear caused by friction.

[0010] It has been found that this effect is due to the manufacturing method and is not limited to a specific material, in other words, unlike a conventionally formed screen, which may be configured as a sheet, the screen body manufactured according to the invention cannot be worn down, for example by surface wear during operation, in such a way that the roughness falls below that required for function.

[0011] In addition, the preferred manufacturing method is, inter alia, because it allows a wide variety of geometries to be produced in a simple manner, whereas the geometries of the screens of the prior art are often predefined by the tool from which they are produced and are not easily changeable. This allows for the production of specifically adapted screens for different operating conditions, for example of a screw press, such as different compositions of the material to be dried, in a simple manner, so that such drying methods can be implemented in a particularly efficient manner. Furthermore, screens with different hole geometries can also be produced in a simple manner for different positions of the screw press, in order to adapt the open surface of the screen to the solids content of the material to be dried, which varies in each case over the length of the screw press.

[0012] Typically, the corresponding materials have a predefined porosity, so that as material is removed from the surface, new surface roughness is still introduced.

[0013] Moreover, such methods also allow the easy production of materials with relatively hard or relatively soft particles, through which a defined roughness can be achieved even in the event of wear. This can be achieved, for example, through different ambient conditions in the 3D printing process, in particular through different temperatures, and / or through different starting materials used during production.

[0014] It is advantageous if the screen body is made of a plastic, metal or ceramic material. Materials of this type have proven to be particularly advantageous for use in sintering or additive manufacturing processes to form the corresponding bodies. Through the material composition as well as the parameters of the manufacturing process, it is also possible to ensure in a simple manner a defined porosity or roughness of the material, which is possibly also achieved when the surface is ground away.

[0015] The use of light materials, such as plastics, also has the advantage, inter alia, that replacement of the corresponding screens in the screw press is significantly easier than in the case of heavier materials.

[0016] Additionally, plastics typically have a lower coefficient of thermal expansion than metals, which also reduces the thermal expansion or thermal stresses that occur between rest and operation due to the high operating temperatures of the screw press, typically 90° C.

[0017] If plastics are used, it is particularly preferred to use plastics having a Shore hardness of more than 50, in particular around 75, measured according to Shore D, in order to achieve a particularly long service life when used in a screw press.

[0018] In order to achieve high strength and high rigidity, it may be provided that fibers are embedded in the screen body during its formation and / or formed within the screen body, in which way, for example, glass or carbon fibers can be embedded in the screen body.

[0019] In order to achieve particularly favorable mechanical properties of the screen body and at the same time an advantageous roughness of the screen body, it may be provided that the screen body is formed of different materials across its thickness, in this way different material properties across the thickness, i.e. along the normal direction to the screen surface, can be achieved in a simple manner.

[0020] In this way, for example in areas spaced apart from the screen surface, a material having higher strength and / or higher rigidity than the screen surface can be used in order to obtain low deformations even under pressures of, for example, 1 to 10 bar, as occurs, for example, in a screw press, and at temperatures of, for example, 90°C, while at the same time ensuring the desired roughness at the screen surface.

[0021] In this connection, it is particularly advantageous if the screen body is made up of a first material forming the screen surface and a second material forming a region of the screen body spaced apart from the screen surface, the second material having a higher rigidity than the first material.

[0022] Furthermore, the screen body has a resistance of at least 45°C, particularly at least 90°C, and 1.5N / mm 2 It is preferably intended that the support be at least partially made of a material which is dimensionally stable under a pressure load of 100 MPa.

[0023] At least 800N / mm 2 and / or a tensile modulus of at least 20 N / mm 2 Preferably, a material having a tensile strength of 0.15 to 0.5 mm is used.

[0024] In order to achieve particularly low thermal stresses or thermal expansion, it is advantageous if materials are used which have a longitudinal expansion coefficient lower than 0.0005, in particular lower than 0.0002.

[0025] Typically, the screen body is formed from a material suitable for use in a wet environment having a pH value of 6 to 9 to provide exceptionally long service life when used in a screw press.

[0026] Furthermore, it is particularly advantageous for the screen body to be formed from a material suitable for a solids content of 3% to 40% of the material conveyed in the screw press, especially for use in screw presses in which cellulose, foodstuffs, and / or sludges are dried.

[0027] In principle, a wide variety of metal, plastic, and ceramic materials can be used to form the corresponding screen body. It is particularly preferred to use a plastic available as of the filing date from asetec GmbH, Rastenfeld, Austria, under the trade name aseTK49, since this plastic has favorable mechanical properties for use in a screw press.

[0028] The material aseTK49 has been shown to be particularly suitable for the corresponding screen body, mainly because it has a strength of about 1650 N / mm 2 Tensile modulus of elasticity of about 15%, elongation at break of 1.5N / mm 2 and 90°C, and 0.4N / mm 2 and dimensional stability at 150℃ and approximately 40N / mm 2 and a tensile strength of approximately 65N / mm 2 The object of the present invention is to form a structure which has a compressive strength of 0.01 to 0.01 mm and at the same time ensures a substantially constant roughness when worn down. Furthermore, the material is suitable for use in a screw press under appropriately humid conditions and at the pH values ​​which occur therein.

[0029] It has been demonstrated that the opening or openings may be formed during a sintering process and / or an additive manufacturing process.

[0030] This results in a particularly simple method compared to conventional methods for producing corresponding screens, in which a large number of holes are usually drilled into a sheet metal to form the screen. Also, in order to avoid clogging of the openings during additive manufacturing or sintering processes, hole geometries in which the cross section of the hole or opening widens from the inside to the outside can be produced in a simple manner. In addition, non-circular openings can in principle also be produced in a simple manner, so that no restrictions are imposed in this respect, although openings with a circular cross section are preferred.

[0031] Typically, a screen that can be used, for example, in a screw press is formed according to the invention using a screen body that is configured according to the invention. The screen typically has a mounting device, by means of which the screen can be connected, for example, to a frame, a screen basket, etc., in order to removably position the screen, for example, in the housing casing of a screw press. The screen can in principle be formed only by the screen body or can include the screen body as a separate body, for example together with other components that serve to mount the screen body in a screw press.

[0032] Another object is achieved according to the invention by a screen of the type mentioned at the beginning, in which the screen body consists of a material formed by a sintering process and / or an additive manufacturing process, in particular by a 3D printing process, and the screen is produced in particular by the method according to the invention.

[0033] A corresponding screen can ensure in a simple manner a particularly long-lasting operation of a screw press or other device, in which a constant friction value of the screen surface or a constant roughness of the screen surface is desirable, mainly because a corresponding roughness is still guaranteed even when parts of the surface are worn. According to the invention, at least the screen body of the screen, i.e. the part of the screen which has the screen surface with the openings, is correspondingly constructed. Of course, it is also intended in principle that the screen is entirely formed in a corresponding manner and constructed integrally with the screen body.

[0034] It is advantageous if the screen body has a defined porosity that is substantially constant up to a defined depth, in particular up to a depth of at least 1 mm. This ensures that the desired roughness is always present on the surface even when a corresponding amount of wear has occurred. Once wear has occurred beyond a defined depth, i.e. beyond a defined distance from the screen surface, it is often necessary to replace the screen or the screen body at all, since otherwise the distance between the transport spiral and the housing jacket would be too wide.

[0035] The screen is preferably intended to be constructed as part of a substantially rotationally symmetrical body, in particular as part of a cylindrical or conical mantle, so that a number of identical screens can be combined to form a substantially rotationally symmetrical body. In this way, the screen can be constructed, for example, as a tile on the inner surface of a cylindrical housing mantle, so that the housing mantle of even very large screw presses can be formed by correspondingly manufactured screens. Furthermore, in this case, replacement of defective screens is also very easily possible. The screen is usually constructed to be thin-walled.

[0036] As a complement to the screen body, the screen usually also has a device for preferably releasable connection to a frame or the like. This device can, for example, be configured as an opening through which the screen can be connected to the frame by means of a screw.

[0037] It is preferably provided that at least one side is provided with a recess, in particular a seam groove or a chamfer, in order to enable a form-fitting fastening of the screen, in particular in the direction normal to the screen surface, which allows a particularly simple fastening in the frame or support basket of the screw press. For example, a T-shaped connecting strip corresponding to the seam groove arranged on each side of the screen can be provided, so that the screen is form-fittingly connected to the frame or support basket via the screw fastening of the T-shaped attachment means.

[0038] Advantageously, a groove is provided on the first side, which is preferably arranged approximately normal to the screen surface, so that the screen can be easily connected to other screens or frames via the side.

[0039] It has proven advantageous if grooves and corresponding projections are arranged on a second side, which is preferably approximately parallel to the first side, so that two accordingly configured screens can be connected via the first and second side by means of the projections and the grooves in a form-fitting and / or friction-fitting manner, in particular by means of a click-fit. For this purpose, it may be provided that the projections are configured with an undercut, so that they can be locked in the accordingly configured grooves.

[0040] The corresponding screens are usually designed flat for use in screw presses, preferably as part of a cylindrical or conical jacket surface, so that the corresponding housing jacket of the screw press acting as a screen can be constructed by a number of screens connected to one another, which can be connected to one another in a form-locking or friction-locking manner, in particular by a click lock, making it particularly easy to mount and remove the corresponding screens.

[0041] In a screw press for separating a liquid from a transport product, which has a screw shaft, a transport helix spirally arranged on the screw shaft, and a housing mantle surrounding it, a transport passage for the transport product to be transported is formed between the screw shaft and the housing mantle, and the housing mantle has at least one screen, whereby the liquid separated from the transport product can be transported through the housing mantle, it is advantageous if the screen is configured according to the present invention.

[0042] As a result, particularly long operating periods of the screw press are possible without loss of function, primarily because function can still be guaranteed even when wear occurs on the surface of the screen body.

[0043] It is preferably provided that the screen extends over only a portion of the circumference of the housing casing which is constructed substantially rotationally symmetrically, in particular cylindrically or truncated conically, which on the one hand simplifies the manufacture of the screen, and on the other hand allows defective screens to be replaced in a simple manner without having to replace the entire housing casing.

[0044] It is preferably intended that a number of identical screens are provided which are connected to one another in a form-fitting and / or friction-fitting manner, in particular by a click-fit. In this way, the housing casing is formed essentially by a number of individual screens which are constructed as if in tiles and are therefore easily replaceable. In this way, the housing casings of even very large screw presses can also be formed by screen bodies or screens which are formed, for example, by a 3D printing method.

[0045] Since the screens constructed according to the invention can be constructed in a simple manner with a wide variety of geometries, it is also contemplated that screens with different hole geometries and / or different open areas are used over the length of the screw press, so that the geometry of the screen can be adapted, for example, to the operating conditions occurring at the respective position in the screw press, in particular to the solids content of the transport to be dried at the respective position, which makes it possible to realize a more efficient method.

[0046] The screen can in principle be arranged on the housing jacket in various ways. It is expedient if the screen is fixed to the housing jacket by means of a fastening means, preferably by means of a screw connection. The fastening means can be designed, for example, as a fastening strip.

[0047] It has proven advantageous for the housing mantle to have a support frame, in particular a support basket, to which the screen is connected in a form-fitting and / or friction-fitting manner, in particular by means of a screw connection, in which case the screen or screens, by means of which the screening function of the housing mantle is realized, can be replaced in a simple manner.

[0048] Typically, the support frame is configured as a support basket. In order to be able to retrofit existing screw presses with the screen of the invention in a particularly simple manner, it is preferably intended that the support basket is made of metal. A support basket of this kind can accommodate both conventionally manufactured screen lamellae and also screens configured according to the invention, so that existing screw presses can be retrofitted with screens configured according to the invention in a simple manner.

[0049] It is preferably provided that the screens are form-fittingly connected to the support frame by means of attachment means, which may for example be configured as attachment strips with a T-shaped cross section and positioned between two screens, so that each one of the screens is connected to the support frame by means of two attachment strips arranged on the sides of the screen.

[0050] It may further be provided that the attachment means are made of the same material as the screen body, in which case it is ensured that the attachment means are subjected to the same frictional wear as the screen body itself, thereby providing an even surface release, whereby a substantially smooth surface is maintained even when wear occurs.

[0051] Typically, the screen consists of a single component formed by a body formed by sintering and / or additive manufacturing, in particular by 3D printing. In this way, the features of the screen that serve for mounting, such as seam grooves, grooves, protrusions, etc., can also be formed in a simple manner during the additive manufacturing process.

[0052] Further features, advantages and operation of the present invention will become apparent from the following detailed description of the preferred embodiment, the drawings of which are included herein and in which: [Brief description of the drawings]

[0053] [Figure 1] FIG. 1 shows a screw press. [Diagram 2]FIG. 2 shows a portion of the housing mantle. [Diagram 3] FIG. 3 shows the screen. [Figure 4] FIG. 4 shows the screen. [Diagram 5] FIG. 5 shows the screen including the support frame and mounting means. [Figure 6] FIG. 6 shows a cross-sectional view of the screen. [Figure 7] FIG. 7 shows a detailed view of FIG. [Figure 8] FIG. 8 shows a detailed view of FIG. [Figure 9] FIG. 9 shows a detailed view of FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0054] 1 shows a screw press 10 according to the invention in a partial cross-sectional view. The screw press 10 is designed for separating liquid from a material to be conveyed, in particular from cellulose, and has a screw shaft 11 arranged in a stationary housing mantle 13 so as to be rotatable about a longitudinal axis 15 by a drive, on which a conveying helix 12 is arranged, so that a conveying passage for the material to be conveyed is formed between the screw shaft 11, the housing mantle 13 and the conveying helix 12. In this way, when the screw shaft 11 rotates about its longitudinal axis 15, the material to be conveyed is conveyed in the conveying passage along the longitudinal axis 15, and pressure is exerted on the material to be conveyed, thereby separating the liquid present in the material. The separated liquid is then conveyed out of the interior of the screw press 10 through the housing mantle 13, which acts as a screen.

[0055] The housing mantle 13 of the screw press 10 is in the illustrated embodiment formed on the inside by a substantially semi-cylindrical mantle member 16, one of which is shown in Figure 2. The mantle member 16 comprises a screen 1 attached to a support basket 14, here made of metal, having openings 18, not shown in Figure 2, for separating solids from liquids during operation of the screw press 10.

[0056] As can be clearly seen, the individual screens 1 are configured here as tiles, i.e. as parts of a cylindrical jacket surface, and are supported radially outwardly on the support basket 14, so that the housing jacket 13 is subjected to an internal pressure of, for example, 1 to 10 bar during operation of the screw press 10, without this leading to significant deformations of the screens 1. The tile-shaped screens 1 are connected in a form-fitting manner to the support basket 14 via fastening means configured as a mounting strip 19 which, when viewed in cross section, is T-shaped and which is connected to the support basket 14 via a screw connection.

[0057] The functioning of the screw press 10 depends primarily on ensuring a defined friction between the transported material and the screen surface 5, since below a defined threshold the transported material is no longer conveyed along the longitudinal axis 15 but instead rotates about its axis of rotation together with the screw shaft 11.

[0058] According to the invention, the screen body, i.e. the part of the screen 1 having the screen surface 5 with the openings 18, is formed by sintering and / or additive manufacturing methods, so that even if, when the transported object slides over the screen surface 5, parts of the surface or the screen surface 5 are worn away, for example by frictional wear, this still results in a screen surface 5 having a predefined minimum roughness, and therefore it is not possible to reach a perfectly smooth surface of the screen body, such that functionality would no longer be guaranteed.

[0059] In this embodiment, the screen 1 is formed entirely by the screen body, but of course, embodiments are also conceivable in which the screen body formed by a corresponding method is removably arranged on a frame of the screen 1, which is formed, for example, from a number of components, and which frame may be made of a different material than the screen body.

[0060] The mounting means, here configured as a mounting strip 19 with a T-shaped cross section, is made of a material corresponding to the screen body and can also be manufactured by a 3D printing method, so that wear of the mounting strip 19 corresponds to wear of the screen body and a substantially cylindrical and smooth surface of the housing mantle 13 is guaranteed on the inside, even when the screw press 10 wears or after long-term operation.

[0061] Figures 3 to 9 show a corresponding screen 1 in detail, with Figure 3 showing the screen 1 in an isometric view, Figure 4 showing the plan view of Figure 1, Figure 5 showing a side view of the screen 1 shown in Figures 3 and 4, including the support basket 14 and part of the mounting strip 19, and Figure 6 showing a cross section along the line VI-VI in Figure 4. Figure 7 shows detail VII of Figure 6, Figure 8 shows detail VIII of Figure 6 and Figure 9 shows detail IX of Figure 6.

[0062] As can be seen, the screen 1 is configured substantially like a cylindrical mantle surface, and the inner screen surface 5 of the screen 1 is provided with a number of openings 18 extending radially through the screen 1. As can be seen in Figs. 6 and 7, the cross section of the openings 18 increases from the inside to the outside or with increasing distance from the screen surface 5. This prevents the openings 18 from clogging in a simple manner and at the same time ensures that only solids having a diameter 17 smaller than the minimum diameter 17 of the openings 18, which in the illustrated embodiment can be 1.5 mm by way of example, are conveyed out of the interior. The openings 18 can be configured with an opening angle α, which can be, by way of example, between 10° and 30°, as can be seen in particular in Fig. 7.

[0063] In order to be able to join the individual screens 1 in a simple manner in the direction of the longitudinal axis 15 of the screw press 10, as can be seen in particular in Figures 6, 7 and 8, the screens 1 or screen bodies are provided with grooves 8 on a first side 6 and with projections 9 corresponding to the grooves 8 on a second side 7 opposite the first side 6. The first side 6 and the second side 7 as well as the grooves 8 and the projections 9 extend in the circumferential direction in the screen 1 shown in this example.

[0064] The projection 9 is shown in detail in Fig. 8. As can be seen, the projection 9 has an undercut 2, which allows the projection 9 to be locked in a groove 8, which is shown in detail in Fig. 9. Thereby, a click mechanism for easily connecting several screens 1 along the longitudinal axis 15 is realized in a simple manner.

[0065] The screen 1 can be attached to the support basket 14 by means of two attachment strips 19 arranged along the screen 1, as shown in Fig. 2. For this purpose, seam grooves 3 corresponding to the cross-sections of the attachment strips 19 are respectively configured on the sides of the screen body which run essentially parallel to the longitudinal axis 15 in the assembled state, so that when the attachment strips 19 are arranged between the two screens 1, a substantially cylindrical inner surface of the housing jacket 13 results, as can be seen in Fig. 5.

[0066] 5 also shows diagrammatically the support basket 14, which is arranged in the screw press 10 behind the screen 1, and the mounting strip 19. As can be seen, the mounting strip 19, which here is configured with an approximately T-shaped cross section, is connected to the support basket 14 by means of screws 4 in order to fix the screen 1 with the support basket 14 in a form-fitting manner.

[0067] Alternatively, holes may be provided in the screen 1 for screwing it directly to the support basket 14 .

[0068] In this embodiment, the screen body and the screen 1 are integrally formed from plastic by a 3D printing process, during which the openings 18 are also formed, thereby achieving a material with a roughness that remains unchanged even when wear occurs on the screen surface 5, thereby ensuring the functionality of the screw press 10 even when the screen body is worn.

[0069] When the screen 1 is formed, different materials can be used to achieve, for example, increasing stiffness and decreasing porosity with increasing distance from the screen surface 5, thereby achieving high stiffness while still achieving favorable tribological properties. In addition, fibers can be embedded in the screen 1 or in the screen body to achieve favorable mechanical properties.

[0070] Thus, the screen 1 constructed according to the invention allows the screw press 10 to operate over particularly long periods without any degradation, mainly because wear on the screen body does not result in a decrease in friction between the transported material and the screen 1. Furthermore, the screens 1 can be constructed in a simple manner, for example with different geometries, so as to be able to provide different screens 1 with different hole geometries and / or different open areas for different operating conditions, which may occur, for example, depending on the transported material to be dried but also depending on the position in the screw press, so that the corresponding drying methods can be carried out particularly efficiently.

Claims

1. A method for manufacturing a screen body for a screen to be used in a screw press, the screen body comprising one or more openings in a screen face, the screen body being formed by an additive manufacturing method, in particular by a 3D printing method, and the screen body being subjected to a pressing force of 1.5 N / mm at a temperature of at least 45° C. ２ 2. A method for manufacturing a screen body, the screen body being at least partially made of a plastic material which is dimensionally stable under a pressure load of 1000 mm.

2. The method of claim 1 , wherein fibers are embedded in and / or formed within the screen body as the screen body is formed.

3. The method of claim 1 or 2, wherein the screen body is formed of different materials across its thickness.

4. 4. The method of claim 3, wherein the screen body is formed of a first material forming the screen surface and a second material forming a region of the screen body spaced from the screen surface, the second material having a higher stiffness than the first material.

5. The screen body has a strength of at least 1.5 N / mm ２ 5. The method according to claim 1 , wherein the molded article is at least partially made of a material which is dimensionally stable under a pressure load of 0.5 to 100 .mu.m.

6. The method of claim 1 or 5, wherein the one or more openings are formed during an additive manufacturing process.

7. A screen for a screw press, comprising a screen body having one or more openings on a screen surface, the screen body being made of a material formed by additive manufacturing, in particular by 3D printing, and the screen body being capable of withstanding a compressive strength of at least 1.5 N / mm at a temperature of at least 45° C. ２ the screen being at least partially formed of a plastic material which is dimensionally stable under a pressure load of .

8. 8. The screen according to claim 7, wherein the screen body has a defined porosity that is substantially constant up to a defined depth, in particular up to a depth of at least 1 mm.

9. 9. A screen according to claim 7 or 8, wherein the screen is constructed as part of a substantially rotationally symmetric body, in particular as part of a cylindrical or conical mantle, whereby a number of identical screens can be combined to form a substantially rotationally symmetric body.

10. 10. A screen according to claim 7, wherein at least one side edge is provided with a cut-out, in particular a seam groove or a chamfer, to enable a form-fitting fixing of the screen, in particular in the direction normal to the screen surface.

11. 11. A screen according to any one of claims 7 to 10, wherein a first side, preferably arranged substantially normal to the screen surface, is provided with grooves.

12. 12. The screen according to claim 11, wherein protrusions corresponding to the grooves are arranged on a second side, which is preferably substantially parallel to the first side, so that two correspondingly configured screens can be connected in a form-fitting and / or friction-fitting manner via the first and second sides by the protrusions and the grooves.

13. A screw press for separating a liquid from a transport product, comprising a screw shaft, a transport helix spirally arranged on the screw shaft, and a housing mantle surrounding the screw shaft, a transport passage for the transport product to be transported between the screw shaft and the housing mantle, the housing mantle having at least one screen, whereby the liquid separated from the transport product can be transported through the housing mantle, the screen being configured according to any one of claims 7 to 12.

14. 14. The screw press of claim 13, wherein the screen extends over only a portion of the circumference of the substantially cylindrical or frusto-conical configured housing mantle.

15. 15. The screw press according to claim 13 or 14, wherein a plurality of identical screens are provided which are connected to one another in a form-fitting and / or friction-fitting manner, in particular by a click-fit.

16. 16. A screw press according to any one of claims 13 to 15, wherein the screen is fixed to the housing mantle by attachment means, preferably by a threaded connection.

17. 17. The screw press according to claim 13, wherein the housing mantle has a support frame, in particular a support basket, and the support frame and the screen are connected in a form-fitting and / or friction-fitting manner, in particular by a screw connection.

18. 18. A screw press according to any one of claims 13 to 17, wherein the attachment means is made of the same material as the screen body.

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