Process for the manufacture of a filter

Abstract

Process for manufacturing a filter composed of fibers for a filter element (38), comprising at least the following process steps: - providing a matrix (37); - forming a filter wall (34) having a gradually increasing wall thickness of a filter medium (35) by depositing the fibers from a suspension into the matrix (37); - stopping the deposition operation upon obtaining a hollow filter body (36) consisting of the filter medium (35) which has a specifiable wall thickness and into which the matrix (37) is at least partly embedded.

Description

[0001] Method for producing a filter

[0002] The invention relates to a method for producing a filter. DE 10 2016 013 166 A1 discloses a filter element designed as a replacement element, the filter medium of which is formed as a hollow body and extends between two end parts, particularly in the form of end caps, and is pleated with individual filter folds. This filter medium comprises a filter material made of cellulose.

[0003] The filter medium consisting of cellulose material can be used with particular advantage in the known solution for separating water from hydraulic oils, whereby the filter medium increases the volume of the water droplets in the water-oil mixture, which sink due to the density difference between water and oil and under the effect of gravity, whereby a separation process takes place under the influence of gravity.

[0004] The cellulose filter medium has a uniform thickness of more than 2 mm, with filter pleats of equal height and identical bending or folding radii on the valley and peak sides. With this uniform thickness and the uniform pleat geometry, a strong coalescence effect can be achieved, enabling particularly effective water separation with the known filter body. To produce the cellulose filter body for a filter medium, a manufacturing process is used that includes at least the following manufacturing steps:

[0005] - Moistening a flat filter mat made of cellulose material, pleating the moistened filter mat using a pleating machine, forming a cylindrical hollow body,

[0006] - Joining the two long sides of the hollow body by means of a welding and / or gluing process, and

[0007] - Drying the cellulose filter body.

[0008] DE 696 24 632 T2 discloses a filter element and a method for its production. The filter element has a cylindrical section formed from a so-called slurry of main fibers and microfibers, of which the main fibers have a fiber diameter of at least five micrometers and microfibers have a fiber diameter of less than five micrometers. A plurality of longitudinal grooves are formed in an outer and / or inner surface of the cylindrical section, whereby the cylindrical section has thin and thick sections around its circumference. The cylindrical section has a fiber density gradient in its circumferential direction, such that the thick section has a low density and the thin section, in contrast, has a high density.

[0009] The known process for producing such a filter element is characterized by the following steps:

[0010] Feeding the slurry containing the main fibers and the microfibers into a liquid container and

[0011] Drawing the slurry into a suction unit which is immersed in the slurry and has an inner mold with openings formed on its surface and a star-shaped cross-section and a suction cylinder accommodated within the inner mold and formed with a plurality of suction openings, wherein the suction openings are arranged substantially uniformly over the entire cylinder surface and the opening rate of the suction cylinder is lower than that of the inner mold.

[0012] This reduces pressure losses during filtration and increases filter efficiency accordingly. In practice, filters manufactured in this way have shown insufficient dirt absorption by the fiber material, especially cellulose, due to the insufficient wall thickness caused by the precoating process. The wall thickness is limited because the cellulose does not adhere to the tool in the form of the separator due to gravity.

[0013] US 201 7 / 0341004 A1 discloses a candle filter having a hollow cylindrical element body which is closed on one side in one piece by a curved dome part and has on its other, opposite side an annular extension relative to its other outer circumference, by means of which the respective candle filter can be suspended vertically in an exchangeable manner in a pot-shaped filter housing for the filtration of hot gas streams.

[0014] The known candle filter can be obtained by vacuum forming in a solid manufacturing mold adapted to the candle shape, into which a suspension is introduced, consisting of high-temperature-resistant inorganic fibers mixed with at least one binder and a carrier liquid, in order to obtain a green body as an intermediate product, which is then dried and further processed towards the finished filter product.

[0015] Based on this prior art, the invention seeks to provide an alternative, improved manufacturing process compared to the known processes. This object is achieved according to the content of claim 1 by a method for producing a filter from fibers for a filter element, comprising at least the following process steps:

[0016] Providing a matrix,

[0017] Construction of a filter wall with gradually increasing wall thickness of a filter medium by washing the fibers from a suspension into the matrix, and

[0018] Terminating the precoating after obtaining a hollow filter body consisting of the filter medium of a predetermined wall thickness in which the matrix is ​​at least partially embedded.

[0019] The use of a matrix creates a kind of stabilizer for the pre-coated fiber layer, particularly the cellulose layer. Thanks to the inherently stable matrix, the fiber material thickens and becomes more stable, resulting in a higher dirt-holding capacity for the element material. The use of a separate matrix structure allows for the production of filter elements with a greater wall thickness and significantly improved dirt-holding capacity compared to conventional solutions.

[0020] With the manufacturing process according to the invention, a largely undisturbed, successive build-up of the filter medium is achieved by the pre-coating of fiber material from the suspension, without the need to use fixed manufacturing molds that already define the geometry of the filter from the outset and thus restrict it.

[0021] The filter element produced by the process according to the invention consists of at least one layer of fiber material, such as cellulose, with the matrix as a stabilizer. The fiber material (cellulose) can be made more open or closed with regard to pore size by adding additional substances, for example, in the form of volatilizing spacers or by mechanical processing. The matrix can protrude visibly from the cellulose.

[0022] In a preferred embodiment of the method according to the invention, the matrix is ​​formed from individual threads and / or fibers that are loosely and / or at least partially connected to one another at nodes. A matrix is ​​understood to be a material in which other components are or can be embedded.

[0023] In a preferred embodiment of the method according to the invention, it is further provided that the threads or fibers of the matrix are randomly oriented in the manner of a nonwoven or provided with a predeterminable orientation within the framework of a woven, knitted, or warp-knitted fabric. In either case, cavities are formed between the threads or fibers, which can be occupied by the washed-up or deposited cellulose material in order to achieve an inherently stable cellulose element structure for a filter element. The structure of the matrix can also predetermine free spaces that are not filled with cellulose. In this respect, the matrix is ​​in any case provided with a predeterminable porosity, whereby the matrix can also basically be formed from a type of sponge with preferably open-pore cavities in the sponge structure for the deposition of the cellulose material during washing.

[0024] In a preferred embodiment of the method according to the invention, it is provided that the matrix is ​​subjected to a thermal treatment in the form of heating before the precoating process and that the precoating of the fibers takes place at least during the subsequent cooling. Depending on the plastic material used for the matrix, this can either contract or expand due to heat, creating additional cavities along the threads that enable a fluid to penetrate deeper into the cellulose, or the cellulose is compressed accordingly, making it more difficult for the fluid to penetrate the cellulose, thus enabling the filter fineness to be adjusted. During cooling of the matrix material, cavities can also form along the threads within the cellulose, which are then not filled with fiber material, such as cellulose, and enable further adjustment options for achieving a predeterminable filter fineness.

[0025] In a further preferred embodiment of the method according to the invention, it is provided that the filter body is subjected to further process steps during or after its production, such as

[0026] Ultrasound treatment and / or

[0027] Pressing and / or

[0028] - Drying.

[0029] Mechanical processing in particular allows the filter body to be made more open or closed in terms of its porosity.

[0030] In a further preferred embodiment of the method according to the invention, the threads and / or fibers of the matrix are made of plastic and / or metal materials. In particular, plastic materials can be used to form adhesive surfaces for the adhesion of the pre-washed fiber material, particularly in the form of cellulose fibers.

[0031] According to the invention, it is further provided that the matrix is ​​constructed as a flat strip material to form a hollow-cylindrical, inherently stable support body, so that the hollow filter body is already inherently stable during the precoating process, which benefits the further, process-reliable construction of the element material. In a preferred embodiment of the method according to the invention, it is provided that the suspension is stored in a tank in which a separation device is accommodated below a liquid level in the tank, which separation device is surrounded by the matrix, and that a pressure gradient is built up by means of a vacuum device acting on a separation device such that the fibers are deposited by precoating, building up the filter wall. This results in a homogeneous filter mat structure with even fiber distribution, which allows presetting within the framework of the desired filtration performance with regard to the filter fineness.Particularly when the separation device is segmented into different pressure ranges, different pressure gradients can be created along the outer wall of the separation device using the vacuum device, allowing a wide variety of geometries to be achieved for the filter body depending on the subsequent application. For example, a thicker wall thickness can be achieved in the base area of ​​the filter body than in the head area. In particular, when fiber material is precoated, a denser fiber material application can be achieved towards the inside of the filter body than on the opposite outside. This gradual build-up leads to favorable filtration behavior for fluid flows that pass through the element material from the outside to the inside. Instead of using a hollow cylindrical support body as a matrix or stabilizer, other geometries can also be used.For example, the matrix could be designed as a hyperboloid of revolution, which leads to increased fiber integration into the matrix at its base and head sections.

[0032] In any case, this allows for the creation of seamless or seamless filter bodies that are circumferentially closed and have a uniform wall thickness that is reinforced by the inclusion of the matrix. Depending on the selected wall thickness for the filter body, including the matrix, both the mechanical load capacity during subsequent filtration operation and the strength that ensures stability can be specified. Depending on the wall thickness, filter bodies and later filter elements can be manufactured that can be adapted to a wide variety of filtration tasks, something that has no equivalent in the state of the art.

[0033] In a further preferred embodiment of the method according to the invention, it is provided that the separation device remains in the tank and the filter body obtained is withdrawn from the separation device and removed from the tank, or that the separation device is designed in the manner of a support tube body and removed from the tank together with the filter body. Since the separation device to be arranged in the tank can be adapted in the manner of a manufacturing tool comparable to a conventional support tube body for the filter element material, the possibility is opened up of leaving the separation device as a support tube body in the filter body in order to complete the process towards a complete filter element, wherein the matrix preferably forms a reliable connection with such a support tube body.On the other hand, keeping the separation device in the tank guarantees a rapid sequence of filter bodies to be produced within the framework of rationalized production.

[0034] Preferably, a method according to the invention further provides that the precoating of the fibers from the suspension is terminated at the earliest after obtaining a filter body closed at one end, consisting of the filter medium of a predeterminable wall thickness, the integral component of which is a stable matrix. Preferably, the filter body, which is closed at the end, is cut free to obtain a hollow-cylindrical element structure with two opposite central openings, while removing the closed end. This results in a smooth cut edge geometry, which improves the bonding of an end cap to the element material, for example, during an adhesive bond.

[0035] The closed end of the filter body, which is preferably formed from a dome, in particular in the form of a shell, particularly preferably in the form of a hollow hemisphere, increases the inherent stability at a free end of the element body in addition to the embedded matrix, so that the precoating process with the fiber material can be carried out with particularly high process reliability. If the method according to the invention allows the production of a filter body that is held between two end caps, a tradable and thus replaceable filter assembly is created as a whole, which can be used for a wide variety of filtration tasks in device housings.

[0036] In this respect, it is preferably provided that at least one end cap is provided with a sealing device arranged in the direction of the adjacent central opening of the filter body. Thanks to the sealing device, the filter element can be connected to third-party components, for example, to fluid-carrying components in a device or filter housing.

[0037] In addition to the solutions described above, the method according to the invention can enable the filter body constructed from fiber material to be surrounded by a further filter medium, preferably in pleated form, in order to achieve effective particle removal in an unfiltered stream passing through the filter body or filter element by means of the further filter medium. The filter element constructed from pre-wetted fibers with a matrix can serve to separate so-called varnish or oil aging products from a fluid stream and / or, as already described in the prior art, can support water separation with regard to the coalescence effect of the fiber material used. In particular, varnish is understood to mean temperature-soluble, usually gel-like aging products of the oil or contaminants thereof.It is particularly advantageous to use cellulose fibers suspended in a large amount of water to form a suspension. This suspension may be provided with additional components, such as fillers, additives, and filter aids. However, the manufacturing process according to the invention need not be limited to cellulose fibers. Ultimately, any fiber material that can be suspended, meets the subsequent filtration requirements, and can be easily incorporated or bonded to a matrix is ​​suitable.

[0038] The manufacturing process according to the invention using the matrix as a stabilizer leads to inherently stable filter bodies and filter elements formed therefrom, the filter medium of which can be seamlessly designed in a variety of geometric shapes with a predetermined wall thickness.

[0039] In the following, the process according to the invention is explained in more detail using a manufacturing device and the products obtained therewith. The figures show, in a schematic and not to scale, the

[0040] Fig. 1 shows a highly simplified structure of the manufacturing device;

[0041] Fig. 2 shows a filter body as obtained with the manufacturing device according to Fig. 1;

[0042] Fig. 3 and 4 show the filter body according to Fig. 2, which in a further manufacturing step results in a hollow cylindrical filter body according to Fig. 4 by means of end cutting according to Fig. 3; once in longitudinal section, once in bottom view and once in perspective top view of the filter body according to Fig. 2 with inserted support tube body forming a filter element as a whole; once in longitudinal section, once in bottom view and once in perspective top view of a filter element body according to Fig. 4 with inserted support tube body to form another type of filter element; The filter element according to Figs. 8 to 10 in a corresponding representation with additional filter medium arranged on the circumference; and a section of the matrix as a fleece in plan view.

[0043] Figure 1 schematically shows a fluid tank 10 used to store a liquid suspension. A separating device 14 is accommodated below a predeterminable liquid level 12 in the tank 10. This separating device 14 has an outer wall 16 traversed by a continuous perforation, which is not shown in Figure 1 for the sake of simplicity. This outer wall 16 has a hollow cylindrical wall section 18 and an adjoining, dome-shaped wall section 20. For stiffening, the outer wall 16 can have a support device 22 constructed from longitudinal and transverse rods. Furthermore, the hollow cylindrical separating device 14, with its outer wall 16 as viewed in the direction of Figure 1, is open towards the bottom and is firmly connected to the relevant tank wall 24, particularly at the transition to the lower tank wall region.A collecting container 28 is connected to the respective fluid tank 10 as part of a vacuum device 26, which is connected on the inlet side to the lower tank wall 24 via a connection 30. The collecting container 28 is connected to a vacuum pump (not shown in detail) via a further connection 32 and connecting line 33, which can generate a negative pressure in the collecting container 28 during operation, as well as on the inside of the outer wall 16 of the separating device 14, which opens with its interior into the media-carrying connection 30. The possible flow direction from the interior of the separating device 14 via the connection 30 to the collecting container 28 and via the further connection 32 and line 33 to a vacuum pump is indicated by arrows in Figure 1.

[0044] The matrix 37, shown in detail in Figure 14, is formed in the present embodiment from a nonwoven fabric 41 with randomly distributed, individual threads 39 of predeterminable length, some of which are firmly connected to one another at nodes. Plastic threads are used, for example made of polyamide, which can be bonded to one another at the individual nodes using heat and pressure or with the use of appropriate binding agents. The production of such random fiber nonwovens is common practice, so it will not be discussed in more detail here. The matrix section according to Figure 14 can be enlarged in all three mutually perpendicular directions; in particular, the thickness of the matrix 37 can be specified within a wide range in order to later obtain cellulose filters with a correspondingly large wall thickness.

[0045] In the present case, the band-shaped matrix material is to be formed into a cylindrical hollow body and closed, in order to then be pushed onto the rod-shaped separation device 14 along its outer wall 16, as shown in Figure 1. The hollow-cylindrical matrix body, as viewed in the direction of Figure 1, ends with its underside at the top of the tank wall 24 and has a height in its axial length that corresponds to the length of the filter element 38 that will later be intended. However, the dome to be formed as the end 20 of the element material can be kept free of the matrix, since the dome-shaped end 20 in question will be cut off anyway, which will be explained in more detail below.

[0046] While the matrix starting material according to Figure 14 initially still has inherent elasticity, so that the hollow cylindrical peripheral shell of the matrix 37 can be pushed particularly well onto the outer wall 16 of the separation device 14, the matrix 37 hardens further as soon as the fiber material is washed or drawn from the suspension into the matrix cavities. Once the fiber material has hardened, usually in the form of cellulose, in the matrix during a subsequent drying process, an extremely inherently stable filter body 36 is created. Compaction of the cavities in the matrix 37 can also be achieved by using the liquid in the fluid tank 10 in a manner similar to an ultrasonic bath.Furthermore, during the production of the filter body 36, it is possible to subject the matrix 37 at the base to ultrasonic vibrations, which can be introduced into the element body, for example, via the lower tank wall 24. Furthermore, it is possible to subject the initially finished filter body 36 to the compressive force of a press (not shown), if necessary before a drying process, in order to thereby reduce the pore size.

[0047] The suspension held in the fluid or storage tank 10 comprises a liquid, for example water, which contains individual fibers not shown in detail. In addition to the respective fiber material, for example made of cellulose, other substances can be part of the suspension. These include, for example, fillers such as silicates (e.g. kaolin), carbonates (e.g. chalk), sulfates (e.g. gypsum or barium sulfate), oxides (e.g. titanium dioxide) and other fiber material, for example in the form of aramid fibers, carbon fibers, etc. Furthermore, additives can be introduced into the suspension, such as sizing agents, binder systems, dry and wet strength agents, pigments, dyes, dewatering and retention agents as well as defoamers. Diatomaceous earth, silica gel, perlite, zeolites and activated carbon, for example, have proven suitable filter aids for the suspension.

[0048] In order to maintain the liquid level 12 in the fluid tank 10, the suspension can be continuously replenished into the fluid tank 10 by means of a supply device (not shown in detail). In any case, however, the liquid level 12 of the suspension covers the separating device 14 along its upper side at a predeterminable distance during the precoating process.

[0049] When the vacuum pump of the vacuum device 26 is activated, a pressure gradient builds up on the outer wall 16 of the separation device 14, with the result that the fibers from the suspension are deposited by pre-coating in the matrix 37, forming a porous filter wall 34. The layered construction of the filter wall 34 thus occurs with a gradually increasing wall thickness of a filter medium 35 by pre-coating the fibers from the suspension. The liquid or aqueous portions of the suspension, after the fibers have deposited in the pore structure of the matrix 37, pass through the perforation in the outer wall 16 of the separation device 14 via the lower connection 30 into the collecting container 28 and from there continue towards the vacuum pump via the further connection 32 and the line 33.The precoating or separation process can continue until a filter cake is deposited in the matrix 37, with a filter wall 34 of a predeterminable wall thickness. In this way, a seamless filter cake or independent filter body 36 can be easily obtained with almost any predeterminable wall thickness. The pressure difference, i.e. the pressure gradient generated by the vacuum device 26, attracts the liquid suspension, which leads to more and more fiber material, particularly in the form of cellulose fibers, being uniformly deposited around the outer wall 16 of the separation device 14 within the matrix 37 until the desired wall thickness for the filter wall 34 is achieved. The achievable wall thickness is limited by the finite differential pressure, which arises because the pores in the matrix 37 become more or less blocked with fiber material over time.

[0050] Once a filter body 36 according to the embodiment shown in Figure 1 has been obtained using the manufacturing method shown, the filter body 36 is removed from the separation device 14 together with the matrix 37 and the separated fiber material, the filter body 36 in question being shown as an example in Figure 2. In this procedure, the separation device 14 remains in the fluid tank 10 and is available for a renewed precoating process with fiber material for the purpose of producing a new filter body 36. In an embodiment not shown in detail, it would be possible to divide the separation device 14 into individual pressure zones which build up different pressure gradients separately from one another in order to thus produce a wide variety of geometries for a filter body 36.It would thus be conceivable to build up a stronger pressure gradient in the base-side area of ​​the separation device 14, so that more fiber material is deposited on the base side and in this way a conical geometry that decreases noticeably towards the top is created on the outside of the filter body 36.

[0051] To complete and produce a filter element 38 as a whole, a support tube body 40, which is formed from longitudinal and transverse bars 42 and 44, respectively, can be introduced into the inside of the filter body 36, which is closed at the top end, as shown in Figures 5, 6, 7. The longitudinal bars 42 form, as shown in Figure 6, a three-winged flow guide body 46, which is radially enclosed at its free ends by the ring-like transverse bars 44. Between the transverse bars 44, a continuous perforation (not shown in detail) is introduced into the outer wall 48 of the support tube body 40 in question, which perforation allows the fluid to be guided downwards on the inside of the support tube body 40 towards a lower end cap 50 when flowing through the filter element 38 from the outside to the inside.The annular end cap 50 has a central opening 52, which is defined at the edge by a sealing ring 54 for sealing the filter element 38 to device parts (not shown in detail) of an associated filter housing. For this purpose, the end cap 50 has, as viewed in the direction of Figure 6 and in particular relative to the longitudinal axis of the filter element 38, two diametrically opposite projecting wings 56, which allow the filter element 38 to be connected in the manner of a bayonet lock to connecting parts of the device housing of a filter device as a whole.

[0052] As Figures 2 and 5 to 7 further show, the filter body 36 has, on its side opposite the end cap 50, a dome-shaped wall part in the form of a half-shell 58, wherein the hemispherical shape merges integrally into the rest of the filter wall 34 with the same wall thickness.

[0053] The support tube body 40 is largely similar to the separation device 14 according to Figure 1, except for the upper dome-shaped wall part 20 of the separation device 14, and in this respect it is also possible, as shown in Figure 1, to remove the filter body 36 obtained by precoating together with the separation device 14 from the tank, so that the filter element 38 according to Figure 5 is then obtained except for the end cap 50. In this case, the hollow cylindrical matrix 37 comprises, preferably in a fixed connection, the hollow cylindrical part of the separation device 16. In this solution, a corresponding separation device 14 would then have to be inserted into the tank 10 for a new separation or precoating process.

[0054] The filter body 36 according to the illustration in Fig. 2 represents a type of intermediate product for obtaining the filter element 38 according to the illustration in Fig. 8. For this purpose, according to the illustration in Fig. 3, the upper, dome-shaped wall part 20 is severed by means of a fictitiously indicated separating cut 60, and according to the illustration in Fig. 4, the hollow cylindrical wall part 18 of the filter body 36 remains, with two opposite central openings 52. According to the illustration in Fig. 8, a correspondingly adapted support tube body 40 with 3-wing geometry can then be inserted, and the end of the filter body 36 is provided with two annular end caps 50, each with a sealing ring 54, in order to complete the filter element 38 as a whole.

[0055] As shown in particular in Fig. 10, at least one of the end caps 50 can again be provided with opposing wings 56 of a bayonet lock for the purpose of connecting the filter element to the connection points of a filter housing (not shown). Furthermore, in an embodiment of a filter element 38 (not shown in detail), it is possible to design one of the two end caps 50, in particular the lower end cap 50, as closed, and in this way the lower central opening 52 in the filter body 36 is closed, so that when flow through the filter element 38 from the outside to the inside and against the supporting effect of the support tube body 40, the filtrate flow is discharged exclusively via the upper annular end cap 50.

[0056] The embodiment of a filter element according to Figs. 11 to 13 largely corresponds to the embodiment shown in Figs. 8 to 10; however, the respective filter body 36 made of fiber material is surrounded by an additional filter medium 62 which, contrary to the illustrations, can also be pleated instead of a hollow cylindrical structure. The respective filter medium 62 can then primarily serve to separate particle contamination from a fluid flow, whereas the inner filter body 36 serves as a filter medium for cleaning so-called varnish, which is not necessarily considered to be particle-contaminated. In this respect, the additional filter medium is supported on its inner circumferential side by the matrix 37. Furthermore, the inner filter body 36 can, as already explained, serve to dewater a fluid flow, since cellulose material in particular has the property of being able to absorb water.In this respect, oil-water separation can also be achieved, provided that the corresponding fluid flow is directed from the outside to the inside through the two-stage filter element 38. However, any remaining particulate contamination can then also be removed by the downstream filter body 36 in addition to the filter medium 62. In this respect, the filter body 36 made of fiber material also removes particulate contamination from a fluid flow.

Claims

Patent claims 1 . A method for producing a filter from fibers for a filter element (38) comprising at least the following method steps: Providing a matrix (37), - Construction of a filter wall (34) with gradually increasing wall thickness of a filter medium (35) by precoating the fibers from a suspension into the matrix (37), ending the precoating after obtaining a hollow filter body (36) consisting of the filter medium (35) of predeterminable wall thickness, in which the matrix (37) is at least partially embedded.

2. Method according to claim 1, characterized in that the matrix (37) is formed from individual threads (39) and / or fibers which are loosely and / or at least partially connected to one another at nodes.

3. Method according to claim 1 or 2, characterized in that the threads (39) or the fibers of the matrix (37) are randomly oriented in the manner of a nonwoven fabric (41) or are provided with a predeterminable orientation within the framework of a woven, knitted or crocheted fabric.

4. Method according to one of the preceding claims, characterized in that the matrix (37) is provided with a predeterminable porosity.

5. Method according to one of the preceding claims, characterized in that the matrix (37) is subjected to a thermal treatment in the form of heating before the precoating process and that the fibres are washed out at least during the subsequent cooling.

6. Method according to one of the preceding claims, characterized in that the filter body (36) is subjected to further process steps during or after its production, such as ultrasonic treatment and / or pressing and / or - Drying.

7. Method according to one of the preceding claims, characterized in that the threads (39) and / or fibers of the matrix (37) are obtained from plastic and / or metal materials.

8. Method according to one of the preceding claims, characterized in that the matrix (37) is set up as a flat strip material to form a hollow cylindrical, inherently stable support body.

9. Method according to one of the preceding claims, characterized in that the suspension is stored in a tank (10) in which a separating device (14) is accommodated below a liquid level (12) in the tank (10), which separating device is surrounded by the matrix (37), and in that a pressure gradient is built up by means of a vacuum device (26) acting on a separating device (14) in such a way that the fibers are deposited by precoating, with the filter wall (34) gradually building up.

10. Method according to one of the preceding claims, characterized in that the separating device (14) remains in the tank (10) and the respective filter body (36) is removed from the tank (10) by the separating device (14). or that the separating device (14) designed in the manner of a support tube body (14) is removed from the tank (10) together with the filter body (36). 1 1. Method according to one of the preceding claims, characterized in that the precoating of the fibers from the suspension is terminated at the earliest after receipt of a filter body (36) closed at one end (20), consisting of the filter medium (35) of predeterminable wall thickness, the integral component of which is the inherently stable matrix (37).

12. Method according to one of the preceding claims, characterized in that the filter body (36) which is closed at the end (20) is cut free in order to obtain a hollow cylindrical element structure with two opposite central openings (52) with the closed end (20) being omitted.

13. Method according to one of the preceding claims, characterized in that the closed end (20) of the filter body (36) is formed from a dome, in particular in the form of a shell, preferably in the form of a hollow hemisphere.

14. Method according to one of the preceding claims, characterized in that the wall thickness of the filter body (36) is formed differently by a differently acting pressure gradient on the separation device (14) and / or that differently designed filter bodies (36) with the matrix (37) as an integral component are produced by means of different geometries of the separation device (14) which are adapted accordingly.

15. Method according to one of the preceding claims, characterized in that the filter body (36) is received between two end caps (50).

16. Method according to one of the preceding claims, characterized in that at least one end cap (50) is provided with a sealing device (54) which is arranged in the direction of the adjacent central opening (52) of the filter body (36). 1 7. Method according to one of the preceding claims, characterized in that the filter body (36) constructed from fiber material in the matrix (37) is surrounded as a whole by a further filter medium (62), preferably in pleated form.

18. Process according to one of the preceding claims, characterized in that the suspension comprises cellulose fibers in plenty of water and is preferably provided with further components, such as fillers, additives and filter aids.

19. Method according to one of the preceding claims, characterized in that the matrix (37) extends over the entire length of the filter body (36) between the two end caps (50).

20. Filter element with a filter body (36), in particular produced by a method according to one of the preceding claims, characterized in that the filter body (36) contains an inherently stable matrix (37) in which fibers are embedded as a filter medium (35).

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