JPH02139010A - Filter device and manufacture of filter medium used for the same device - Google Patents

Abstract

PURPOSE:To lower required filter pressure, increase filter speed and make clogging of filter medium hard to generate by driving a cake peeling component slidable in the axial direction to an inner wall surface of a cylindrical filter medium with a driving means in the axial direction. CONSTITUTION:An inner wall surface 3 formed smoothly and a number of micro-through-holes 5 increasing their diameters from the inner wall surface 3 closer to an outer wall surface 4 are provided in a cylindrical filter medium 2. A cake peeling component 22 is installed slidable in the axial direction to an inner wall surface of said filter medium 2 with a driving means 20. As a result, required filter pressure can be lowered and filter speed can be increased, and also clogging of the filter medium can be made hard to generate, and also a cake can easily and securely be peeled off the filter medium so that said filter medium can be used continuously for a long time.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a filtration device and a method for producing P material used in the device.

[Prior Art] Conventionally, there are many types of filtration devices, and these are usually batch-type filtration devices such as pressure filters and leaf filters, vacuum rotary filters, vacuum disk filters, and gravity cylinders. The filtration devices can be broadly divided into continuous filtration devices such as shaped filters, but in any type of filtration device, the selection of the material used in the device is very important. The filter media has various characteristics such as the type of stock solution, pressure, temperature,
Depending on the filtration conditions such as viscosity, corrosion resistance, mechanical strength, durability, heat resistance, filter slag! This is because various performances such as ease of separation are required.

However, the filter media currently in use are sawa paper, furnace cloth (
(cotton cloth, synthetic fiber cloth, etc.), fibrous bodies (glass fiber, asbestos, etc.), mesh bodies (wire mesh, synthetic resin mesh, etc.), metal plates machined with minute through holes, sponge-like metal plates, porous ceramic plates, etc. There are only traditional methods available, and the reality is that among these, the one most suitable for the filtration device and filtration conditions is selected and used.

[Problems to be Solved by the Invention] Both of the above-mentioned types of filtration devices have the following problems due to the use of the above-mentioned conventional swamp material.

■ Filter media using filter paper, furnace cloth, fiber bodies, etc. are subject to severe wear and tear. In addition, filter sludge separated from the stock solution adheres to the surface of these P materials, but at the same time, undissolved solid particles that are part of this filter sludge tend to clog the microscopic holes of the filter media, so the filter sludge is removed from the P material. Even if the slag is peeled off, clogging is difficult to eliminate. Therefore, these sawn materials become disposable after a short period of time,
Continuous use for a long period of time is not possible.

■ The P material that uses the mesh has fine undulations made of thin metal wires and synthetic resin wires, and the filter slag separated from the stock solution adheres to the undulations by entering the recesses of the undulations. It is very difficult to completely remove this filter cake. Therefore, they often end up becoming severely clogged and become disposable after a relatively short period of time.

(2) In the P material using a metal plate machined with minute through-holes, the diameter of the through-holes remains small and constant throughout the entire plate thickness, so the aE dynamic resistance of the P liquid is large. Therefore, the required filtration pressure is large. There is a fatal problem of low overspeed. Further, since the through-holes are easily clogged with undissolved solid particles and difficult to remove, continuous use over a long period of time is also difficult.

■ Filter media using sponge-like metal plates or porous ceramic plates have a structure in which the numerous pores communicate in a complicated detour within the thickness of the plate, and do not penetrate through the slate, resulting in a chain. Removal of undissolved solid particles that clog the pores is nearly impossible. Therefore, it gets clogged severely and becomes disposable after a short period of time.

The present invention can lower the required filtration pressure and increase the filtration speed, and the filter material is less likely to be clogged and the filter slag can be easily and reliably peeled off from the filter material. Therefore, the filter material can be continuously used for a long period of time. It is an object of the present invention to provide a novel filtration device that can also be used and a method that allows the filter medium to be manufactured easily and efficiently.

[Means for Solving the Problems] A filtration device according to claim 1 includes a cylinder having a smooth inner wall surface and a large number of minute through holes whose diameter increases from the inner wall surface toward the outer wall surface. The filter includes a filter medium having a shape, a filter dregs peeling member that can slide in the axial direction with respect to an inner wall surface of the filter medium, and a driving means for driving the filter dregs peeling member in the axial direction.

A filtration device according to a second aspect of the present invention includes a cylindrical P material having a smoothly formed outer wall surface and a large number of minute through holes whose diameter increases from the outer wall surface toward the inner wall surface; The filter includes a slag peeling member that can slide in the axial direction with respect to the outer wall surface of the filter, and a driving means for driving the sludge peeling member in the axial direction.

The method for manufacturing R material according to claim 3 includes the steps of: smoothing the outer wall surface or inner wall surface of a mandrel formed in a columnar or cylindrical shape; providing a conductive coating on the outer wall surface or inner wall surface of the mandrel; A step of forming a large number of minute non-electroconductive parts on the conductive film, and forming a cylindrical rod material by electroforming the surface of the conductive film, and at the same time forming minute non-electrodeposited parts on the non-conductive parts. A step of forming a large number of minute through holes in the R material by growing them as electroforming progresses;
The method includes a step of removing the mandrel from the P material by melting, softening, melting, or destroying the entire or surface portion of the mandrel.

The method for producing a filter medium according to claim 4 includes the steps of: smoothing the outer wall surface or inner wall surface of a mandrel formed in a columnar or cylindrical shape; providing a conductive coating on the outer wall surface or inner wall surface of the mandrel; A process of providing a large number of minute non-electroconductive parts and forming a cylindrical filter medium by electroforming the surface of the conductive coating, and at the same time electroforming the minute non-electrodeposited parts generated in the non-conductive parts. a step of forming a large number of minute through holes in the filter medium by growing it as the process progresses;
The method includes the step of removing the mandrel from the filter medium by applying a thermal expansion difference between the filter medium and the mandrel to separate them.

[Function] In the filtration device according to the first aspect, since the diameter of the through-hole provided in the P material increases from the inner wall surface toward the outer wall surface, the flow resistance of the furnace liquid is small.

Therefore, the required filtration pressure can be reduced and the filtration rate can be increased. Further, the through holes are hardly clogged with undissolved solid particles.

Further, since the inner wall surface is formed smoothly, the filter dregs attached to the inner wall surface can be easily and reliably removed by simply sliding the filter dregs removing member, leaving almost no residue behind.

Also in the filtration device of claim 2, the diameter of the through hole provided in the p-material increases from the outer wall surface toward the inner wall surface, and furthermore, the outer wall surface is formed smooth, so that It has the same effect as a filtration device.

In the method for manufacturing R material according to claim 3, since the outer wall surface or inner wall surface of the mandrel is finished smooth, a filter medium having a smooth inner wall surface or outer wall surface can be formed by electroforming. In addition, because the through holes are formed by growing minute non-electrodeposited parts at the same time as the electroforming of the P material, the diameter increases from the inner wall surface to the outer wall surface or from the outer wall surface to the inner wall surface of the P material. Through holes can be formed easily and efficiently. In addition, after the electroforming of the filter medium, the smooth outer wall surface or inner wall surface of the mandrel and the smooth inner wall surface or outer wall surface of the filter medium strongly adhere to each other through the conductive coating, but when washing with water, the entire or surface portion of the mandrel The mandrel can be easily removed from the P material without applying great force.

Similarly to the method for manufacturing P material according to claim 4, the method for manufacturing R material according to claim 4 also has a smooth inner wall surface or outer wall surface, and a diameter that increases from the inner wall surface to the outer wall surface or from the outer wall surface to the inner wall surface. A P material having an increasing number of through holes can be easily formed. Further, after the P material is electroformed, a difference in thermal expansion is applied to the filter medium and the mandrel to separate them, so that the mandrel can be easily removed from the filter medium without applying a large force.

[Example] Hereinafter, an example of a filtration device embodying the present invention will be described with reference to FIGS. 1 to 6.

The filter medium 2 used in the filter device 1 of this embodiment is a cylindrical one formed by electroforming nickel or other metal, and has a smooth inner wall surface 3. It is equipped with an outer wall 4 that does not require an outer wall. Here, "smooth" refers to a state in which the smoothness of the portion excluding the next through hole 5 is increased to a mirror surface or a fine satin finish or a hair-like state. The dimensions of this filter medium 2 can be determined as appropriate depending on the amount of passing stock solution, filtration speed, etc., but in this example, the inner diameter is 60 mm, the outer diameter is 68 mm, and the wall thickness is 4 mm.
, the height is 75mm).

Further, a large number of fine through holes 5 whose diameter increases from the inner wall surface 3 toward the outer wall surface 4 are formed in the filter medium 2 at the same time as the electrode formation. The diameter of these through holes 5 and the number per unit area can be determined as appropriate depending on the size of the filter dregs particles, the required filtration rate, etc., but in this example, the diameter of the through holes 5 is set at the inner wall surface 3. 10 to 200 μm, and 1 to 4 mm on the outer wall surface 4 (therefore, the through holes 5 may be connected in the middle), and the number of through holes 5 per unit area is 50 to 200/cm 2 . In addition, through hole 5
Although there is no particular limitation on how the diameter of the bowl expands, in this embodiment, as shown in FIG. It is designed to expand in diameter.

A cylindrical outer cylinder 6 with an inner diameter of approximately 100 mm and a height of 75 mm is disposed coaxially around the filter medium 2 to cover it, and these filter medium 2 and outer cylinder 6 are connected to a lid body 7 and a bottom plate body described below. 8
It is clamped by. That is, the upper ends of the filter medium 2 and the outer cylinder 6 are covered with a disc-shaped lid 7 having a raised portion 9 in the center, and the inner annular groove 10 provided on the lower surface of the lid 7 is covered with the lid 7. The upper end of the r material 2 and the upper end of the outer cylinder 6 are respectively fitted into the annular groove 11 on the outside.

Further, at the lower ends of the filter medium 2 and the outer cylinder 6, an inner wall surface 3 of the filter medium 2 is provided.
A disc-shaped bottom plate body 8 with a through hole 12 in the center that is continuous with the
is arranged, and the lower end of the filter medium 2 is placed in the inner annular groove 13 provided on the upper surface of the bottom plate body 8.
The lower end portions of the outer tubes 6 are fitted into the outer tubes 4, respectively. and,
The lid body 7 and the bottom plate body 8 are fixed to the outer cylinder 6 by bolts 16 and nuts 17 inserted through them and a protruding plate 15 provided on the outer cylinder 6.

A supply plug 19 that opens into the pre-filtration chamber 18 inside the filter medium 2 is attached to the side of the raised portion 9 of the lid 7, and a supply pipe 39 for supplying the stock solution P is connected to the supply plug 19. ing. Further, a peeling cylinder 20 as a driving means for driving the next r slag peeling member 22 in the axial direction is housed downward on the upper surface of this raised portion 9.
A disk-shaped filter dregs peeling member 22 that can slide in the axial direction against the inner wall surface 3 of the filter medium 2 is attached to the rod 21 of No. 0 by bolts 23. Further, an annular furnace stagnation hole 51 is provided on the inner wall surface of the raised portion 9, in which the remainder of filter dregs R (described later) is temporarily collected, and an air passage 52 is connected to the P stagnation hole 51 from the outside of the lid body 7. is now open.

A discharge plug 25 that opens into the post-filtration chamber 24 outside the r material 2 is attached to the bottom plate 8, and a discharge pipe 40 for discharging the furnace liquid Q is connected to the discharge plug 25.

Further, a base 26 and a substrate 27 at the bottom thereof are fixed to the lower surface of the bottom plate body 8 with bolts 28.
An oblique hole 29 that is continuous with the through hole 12 of the bottom plate body 8 and a discharge hole 30 with a cylindrical surface are provided inside the base plate 527, and a discharge port 31 that is continuous with the discharge hole 30 is provided in the base plate 527. .

Further, a discharge member 32 formed by cutting out a plane part 33 in a part of a cylindrical body is slidably disposed in the discharge hole 30 of the base 26, and the discharge member 32 is attached to the base via a support shaft 34. It is rotatably pivoted to the stand 26. A pinion 35 is fixed to the end of the support shaft 34 protruding from the base 26, and a discharge cylinder 36 fixed to the base plate 27 is attached to the pinion 35.
A rack 38 provided on a rod 37 is engaged with the rack 38.

Next, a method for manufacturing the r-material 2 used in the filter device 1 will be explained with reference to FIGS. 7 to 10.

■ As shown in FIG. 7, the outer wall surface of the metal cylindrical core material 42, which is sandwiched between the flanges 43 provided on both edges of the cylindrical core material 42, can be cut or ground. A surface portion 44 is formed by applying and curing a polymeric material soluble in at least one type of solvent, and a cylindrical mandrel 41 is constructed by peeling off the cylindrical core material 42 and surface portion A4.

Examples of the polymer material include hard vinyl chloride resin,
Examples include synthetic resin materials such as polystyrene resin, AS resin, ABS resin, methacrylic resin, polyamide resin, polycarbonate resin, polyester resin, and epoxy resin, and rubber materials such as hard rubber.

■ A shaft 4 protruding from the center of both end faces of the mandrel 41
5 is chucked onto a lathe (not shown) or the like, and the cylindrical outer wall surface 46 of the mandrel 41 is smoothed using a cutting tool 47 or a grinding tool, as shown in FIG. If necessary, the mandrel 41 is washed with water, detergent, solvent, etc. to remove dust and oil adhering to the outer wall surface 46, and then dried.

(2) Spray a mixture of pasty silver lacquer, butyl acetate and vinyl chloride lacquer on the outer wall surface 46 of the mandrel 41 and dry it to form a conductive coating 48 as shown in FIGS. 8 and 9. , a large number of minute non-conductive parts 49 made of the vinyl chloride lacquer particles.
are formed in a scattered manner. The surface of this conductive coating 48 is formed to be smooth and follow the outer wall surface 46 of the mandrel 41 .

In addition, by adjusting the mixing ratio of the vinyl chloride lacquer and changing the size and number of non-conductive parts 49 per unit area, the diameter and number of through holes 5 per unit area can be adjusted arbitrarily in the next electroforming process. can be changed to

(2) Subsequently, the mandrel 41 is immersed in a special plating solution (not shown) that contains nickel sulfamate and boric acid as main components and does not contain a surfactant for suppressing pinholes. When electricity is applied between this mandrel 41 (cathode) and a nickel electrode (anode) (not shown), nickel is electrodeposited on the conductive coating 48 as shown in FIG. 9, and as shown in FIG. 2 is electroformed including unnecessary parts at both ends.

At this time, as shown in FIG.
Therefore, by growing these non-electrodeposited parts 50 as the electroforming progresses, the large number of minute through-holes 5 with the enlarged diameter can be formed. can be formed.

Further, the inner wall surface 3 of the filter medium 2 is formed to be smooth and follow the outer wall surface 46 of the mandrel 41 and the surface of the conductive coating 48 .

(2) The shaft 45 of the mandrel 41 is chucked in a lathe (not shown), and the outer wall surface 4 of the filter medium 2 is cut with a cutting tool 47 as shown in FIG. This cutting is performed to make the thickness of the filter medium 2 uniform and to remove protrusions on the edges of the through holes 5, and it is not necessarily required to finish the outer wall surface 4 smoothly.

■ Next, as shown in FIG.
Cut it off along with it.

Even if an attempt is made to remove the mandrel 41 from the filter medium 2 in this state, it is difficult to remove it with normal force. This is because the smooth outer wall surface 46 of the mandrel 41 and the smooth inner wall surface 3 of the filter medium 2 are strongly attached to each other via the similarly smooth conductive coating 48. In particular, mirror surfaces adhere strongly to each other, making it almost impossible to remove them.

However, in this embodiment, the filter medium 2 and the mandrel 41 are immersed in a solvent (not shown), and the mandrel 41 is
In order to melt the polymeric material forming the surface portion 44 of
can be easily removed.

Through the above steps, the filter medium 2 is completed.

Next, a method for filtering the stock solution P and a method for peeling off the filter dregs R using the above-mentioned filtration device 1 will be explained.

(1) First, as shown in FIG. 1, by moving the rod 37 of the discharge cylinder 36 backward, the flat portion 33 of the discharge member 32 is directed upward, and the discharge hole 30 is closed by the discharge member 32. Then, the stock solution P to be filtered is supplied to the pre-filtration chamber 18 through the flow path of a pump (not shown), a valve device (not shown), a supply pipe 39, and a supply plug 19. This stock solution P is separated into insoluble solid particles and furnace liquid Q by a large number of minute through-holes 5 provided in the filter medium 2, and the insoluble solid particles adhere to the inner wall surface 3 of the filter medium 2 and become filter dregs R. Become. Further, the furnace liquid Q flows into the post-filtration chamber 24 through the through hole 5 and is discharged through the discharge plug 25 and the discharge pipe 40.

At this time, since the diameter of the through hole 5 increases from the inner wall surface 3 toward the outer wall surface 4, the flow resistance of the furnace liquid Q is small. Therefore, the required filtration pressure can be reduced and the filtration rate can be increased. Furthermore, the through holes 5 are hardly clogged with undissolved solid particles.

(2) As the above-mentioned filtration progresses, the thickness of the filter dregs R adhering to the inner wall surface 3 of the baffle material 2 increases, and the filtration efficiency decreases.

Therefore, after a predetermined period of time has elapsed, by temporarily switching the valve device (not shown), the stock solution P is transferred to the supply pipe 3.
The water is circulated in the pipe line before 9 and is not supplied to the pre-filtration chamber 18.

Then, as shown in FIG. 2, by lowering the rod 21 of the peeling cylinder 20, the filter cake peeling member 22 is lowered while sliding on the inner wall surface 3, and the filter cake R is peeled off from the inner wall surface 3. let At this time, since the inner wall surface 3 is formed smoothly, it is possible to easily and reliably peel off the ridge R without leaving much of it on the inner wall surface 3.

In this way, according to the filtration device 1 of the present embodiment, by only taking a short time to peel off the filter slag R at predetermined intervals, the filter medium 2 can be used continuously for a long period of time without being replaced at all. be able to.

(3) The filter dregs peeling member 22 descends into the through hole 12 of the bottom plate body 8 as shown in FIG. Compress it by surrounding it with . Therefore, the liquid contained in the filter cake R is squeezed out (deliquified), and a lumpy filter cake R is obtained.

Although this compressing operation of the filter dregs R is not an essential requirement of the present invention,
By forming the filter dregs R into a lump, its volume is reduced, and the handling properties are also significantly improved. Further, in this embodiment, since the peeling and compression of the filter dregs R can be performed at the same time, the efficiency is also high.

(4) Next, as shown in FIG.
By moving the rod 37 forward, the discharge member 32 is rotated together with the lumpy slag R placed on the flat part 33, and finally the flat part 33 is directed downward and the slag R is delivered to the discharge port 31.
discharge from.

After that, the rod 21 of the peeling cylinder 20 is raised. At this time, even if a small amount of filter dregs R remains on the inner wall surface 3 of the filter medium 2, the filter dregs R is pushed up by the filter dregs peeling member 22 and accumulates in the P retention chamber 51, so that the filter dregs R remains. After the peeling member 22 is completely raised, the air passage 52
By blowing air into the slag tank 51, the filter dregs R can be dropped.

After that, switch the valve device (not shown) and perform the above (1).
What is necessary is just to repeat the process of - (4).

It should be noted that the present invention is not limited to the configuration of the above-mentioned embodiments, and may be modified and embodied as desired without departing from the spirit of the invention, for example, as described below.

(1) Contrary to the above embodiment, a cylindrical filter medium is formed with a smooth outer wall surface and a large number of minute through holes whose diameter increases from the outer wall surface toward the inner wall surface. It is also possible to filter the stock solution by flowing it from the outer wall surface to the inner wall surface. In this case, the filter dregs peeling member has a perforated disc shape that can slide in the axial direction with respect to the outer wall surface of the filter medium. As for the driving means for the filter dregs peeling member, the same one as in the above embodiment can be used.

Further, the method for manufacturing the above-mentioned sill material is the same as that of the above embodiment except that the inner wall surface of the cylindrical mandrel is smoothed and a conductive coating is provided on the inner wall surface of the mandrel.

(2) The filter medium 2 may be formed into a tubular shape other than a cylinder, for example, a square tubular shape. Accordingly, the mandrel 41 can be formed in a column shape other than a cylinder, for example, in a square gauze shape. Further, the mandrel 41 may have a hollow cylindrical shape.

(3> The drive means for the filter dregs peeling member 22 is not limited to the peeling cylinder 20, and may be an electromagnetic solenoid, for example.

(4) The method of providing the conductive film 48 on the outer wall surface 46 of the mandrel 41 is not limited to the method of the above embodiment, and for example, silver mirror reaction may be used.

(5) The method of providing a large number of minute non-conductive parts 49 on the conductive coating 48 is not limited to the method of the above embodiment, and for example, insulating particles (for example, vinyl chloride lacquer) may be sprayed on the surface of the conductive coating 48. Accordingly, a non-conductive portion 49 can also be provided.

(6) Regarding the step of fitting and removing the 'mandrel 41 from the P material 2, the following alternative example may be used.

(2) The entire mandrel 41 is formed from the polymeric material of the above embodiment, and after electroforming the P material 2, the mandrel 41 is removed from the P material 2 by dissolving the entire mandrel 41 with a solvent.

■ After forming the entire or surface portion 44 of the mandrel 41 from plaster and electroforming the filter medium 2, the mandrel 41
By dissolving the whole or surface part 44 with hydrochloric acid,
The mandrel 41 is removed from the filter medium 2. Note that when foamed gypsum is used, it can also be dissolved with water.

■ The entire or surface portion 44 of the mandrel 41 is coated with (a) a thermoplastic resin whose softening temperature is lower than the melting temperature of the finished material 2, (b)
) of a metal with a low melting temperature, (C) wax, etc., and after electroforming the P material 2, heat the entire or surface portion 44 of the mandrel 41 to soften or melt the P material 2. Remove mandrel 41.

(2) The entire mandrel 41 or the surface portion 44 is made of a material such as plaster that can be easily destroyed, and after the finished material 2 is electroformed, the entire mandrel 41 or the surface portion 44 is destroyed, so that the filter medium 2 is completely removed. Remove mandrel 41.

■ Almost all of the mandrel 41 is made of a material with a coefficient of thermal expansion different from that of the material of the filter medium 2, and after electroforming the finished material 2, a difference in thermal expansion is applied to the filter medium 2 and the mandrel 41 to separate them. By this, from the filter medium 2 to the mandrel 41
remove. This method also produces the same effects as the embodiments described above.

[Effects of the Invention] Since the present invention is configured as described above, it has the following excellent effects.

According to the filtration device of claim 1 or claim 2, the required filtration pressure can be lowered and the filtration speed can be increased, the filter material is less likely to be clogged, and the filter slag can be easily and reliably peeled off from the finished material. Therefore, the P material can be used continuously for a long period of time.

According to the method for manufacturing a filter medium according to claim 3 or 4, it is possible to easily and efficiently manufacture a filter medium used in the above-mentioned filtration device.

[Brief explanation of the drawing]

1 to 6 show examples of the filtration device embodying the present invention, FIG. 1 is a side sectional view when filtration is progressing, FIG. 2 is a side sectional view when filter dregs are peeled off, and FIG. FIG. 4 is a side sectional view when dregs are being compressed, FIG. 4 is a side sectional view when dregs are being discharged, FIG. 5 is a front sectional view when filtration is progressing, and FIG. 6 is a partially enlarged perspective view of the filter medium. 7 to 10 show examples of the method for producing filter media, FIG. 7 is a cross-sectional view when manufacturing the mandrel, FIG. 8 is an enlarged cross-sectional view of the main part when the filter media is electroformed on the mandrel, and FIG. The figure is a cross-sectional view when the outer wall surface of the filter medium is cut, and FIG. 10 is a cross-sectional view when both ends of the filter medium and the mandrel are cut off. 1... Filter device, 2... Filter medium, 3... Inner wall surface 44
... Outer wall surface, 5 ... Through hole, 20 ... Peeling cylinder, 22 ... Filter dregs peeling member,
41... Mandrel, 44... Surface portion, 46...
Outer wall surface, 48... Conductive coating, 49... Non-conductive part, 5
0...Non-electrodeposition part.

Claims (1)

[Claims] 1. Smoothly formed inner wall surface (3); and the inner wall surface (3)
A cylindrical filter medium (2) equipped with a large number of minute through holes (5) whose diameter increases as it goes toward the outer wall surface (4); A filtration device comprising: a sludge peeling member (22) that can slide in the axial direction; and a driving means (20) for driving the sludge peeling member (22) in the axial direction. 2. A cylindrical filter medium having a smoothly formed outer wall surface and a large number of minute through holes whose diameter increases from the outer wall surface toward the inner wall surface, and an axial direction with respect to the outer wall surface of the filter medium. A filtration device comprising: a filter dregs peeling member that can slide; and a driving means for driving the filter dregs peeling member in an axial direction. 3. Smoothly finishing the outer wall surface (46) or inner wall surface of the mandrel (41) formed in a columnar or cylindrical shape, and applying a conductive coating (48) on the outer wall surface (46) or the inner wall surface of the mandrel (41). In addition to providing the conductive coating (48
), forming a cylindrical filter medium (2) by electroforming the surface of the conductive coating (48), and at the same time forming a cylindrical filter medium (2).
9) forming a large number of minute through-holes (5) in the filter medium (2) by growing the minute non-electrodeposited portions (50) generated in step 9 as electroforming progresses; and the mandrel (41). By dissolving, softening, melting or destroying the whole or surface portion (44) of the filter medium (2
) removing the mandrel (41) from the filter medium. 4. Smoothly finishing the outer wall surface (46) or inner wall surface of the mandrel (41) formed in a columnar or cylindrical shape, and applying a conductive coating (48) on the outer wall surface (46) or the inner wall surface of the mandrel (41). In addition to providing the conductive coating (48
), forming a cylindrical filter medium (2) by electroforming the surface of the conductive coating (48), and at the same time forming a cylindrical filter medium (2).
forming a large number of minute through-holes (5) in the filter medium (2) by growing the minute non-electrodeposited portions (50) generated in step 9) as electroforming progresses; and a step of removing the mandrel (41) from the filter medium (2) by applying a thermal expansion difference to the mandrel (41) and peeling them apart.