JP2003024727A - Sintered filter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a sintered filter capable of enhancing pressure-resistance strength while reducing the number of parts in improving the sintered leaf filter, which is suitably employed particularly as the leaf filter. SOLUTION: The sintered filter is consisted of two thin plate filter media to be folded and forms a filtering chamber between the inner faces of these filter media by closing either one of the outer periphery or the inner periphery of them. The sintered filter is characterized by having the pressure-resistant structure which is durable for the predetermined outside filtering pressure by providing with a supporting part protruding to the opposed side in at least one of the inner faces of the filter media and bringing the supporting part in contact with the other filter medium.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sintered filter which can improve the pressure resistance while reducing the number of parts and can be suitably used as a leaf filter.

[0002]

2. Description of the Related Art Sintered filters, especially leaf filters, are often used to remove impurity particles in molten polymers, various liquids such as waste liquids, or various fluids such as gases.

[0003] This leaf filter is a filter medium combination body in which a filter medium of a thin plate-like filter medium is closed at an inner peripheral portion or an outer peripheral portion thereof, and is usually densely stacked in multiple stages around a shaft material forming an outflow passage to form a housing. It is used as a filter by storing it. As described above, the filtering device using the leaf filter has excellent filtering ability, and by increasing the number of leaf filters, it is possible to adjust the filtering ability by increasing the filtering area per installation area, and thus the handling ability is excellent. There is.

By the way, as the filtering function of the filter,
Generally, so-called "surface filtration" for removing foreign substances on the surface of the filtration surface, or "deep layer" for trapping impurity particles while the fluid is passing through the inside by making the thickness of the filter medium relatively thick Filtration "is known.

In this case, when the fluid to be treated is a low-viscosity fluid such as water or gas, it can be relatively easily filtered under a capillary phenomenon or a low pressure of about natural pressure, but a polymer or the like is used. For such high viscosity fluids,
Since the filtration holes are fine and the filtration resistance is large compared to viscosity, pressure filtration for forcibly pressurizing the fluid is required,
The pressure is about 20 MPa.

Therefore, as a filter used for such high-pressure filtration, a metal powder sintered body which is excellent in strength as a filter medium, as proposed by Japanese Utility Model Laid-Open No. 6-41840, for example, can withstand the filtration pressure. On the other hand, it is known that a pressure-resistant spacer member using, for example, a coarse mesh of about # 8 is inserted in a filter chamber formed between the filter media.

[0007]

However, in the conventional leaf filter using such a coarse mesh, although the mesh is woven by intersecting the wire rods and the cost is low and the pressure resistance is satisfactory, the wire rod of the mesh is Since the outflow of the filtrate is easily blocked and the volume ratio of the mesh in the filtration chamber is relatively large, the flow of the processing fluid is impeded, resulting in pressure loss and the retention of vortices during outflow. As a result, it tends to contribute to the generation of gel.

Further, since a narrow deep portion is formed at the intersecting portion of the wire rod, the polymer that has penetrated into the inner portion is deposited in the deep portion and, after the deposition proceeds, it flows out as a gel due to pressure, resulting in a cleaned treatment. The foreign matter is mixed again in the liquid, which deteriorates the quality of the processing fluid, and the pressure-resistant member such as the mesh increases the number of filter constituent members and hinders the productivity of the filter.

The present invention is based on the fact that the inner surface of one of the filter media is provided with a convex support portion projecting toward the opposite side.
It is an object of the present invention to provide a sintered filter that withstands filtration pressure, improves filtration accuracy, and has excellent productivity.

[0010]

According to a first aspect of the present invention, two filter media in the form of thin plates are superposed on each other, and either the outer peripheral portion or the inner peripheral portion is closed, whereby the filter medium is closed. Is a sintered filter that forms a filtration chamber between the inner surfaces of at least one of the filter media, and a support portion protruding toward the opposite side is provided on the inner surface of at least one of the filter media, and the support portion is brought into contact with the other filter media to provide a predetermined external It is characterized by a pressure resistant structure that can withstand the filtration pressure.

With such a structure, it is possible to omit a pressure-resistant member such as a mesh, suppress an increase in filtration resistance, improve filtration quality, and enhance productivity.

According to a second aspect of the present invention, in the filter medium provided with the supporting portion, the average density of the supporting portion region provided with the supporting portion is lower than the average density of the non-supporting portion region having no supporting portion. The invention according to claim 3 is characterized in that the support portion is formed by radially extending from the central portion of the filter medium in the radial direction.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of the present invention will be described below with reference to the drawings.

1 and 2 show a sintered filter 1 of the present invention.
FIG. 2 is a plan view showing a case where the leaf filter is configured as a leaf filter, and a cross-sectional view thereof, wherein the leaf filter has a thin plate shape,
In this example, two disk-shaped filter media 2a and 2b (collectively referred to as filter media 2) are stacked, and the outer peripheral portion 3 is integrally closed to form a filter chamber 12 inside,
The inner peripheral portion 4 of the filter medium 2 is integrally connected to the core metal 7 arranged in the central through hole 5. As is well known, the leaf filter is constructed as a filter device by bringing the core metal fitting 7 into watertight contact, inserting it into the shaft member 9 indicated by the alternate long and short dash line, stacking it, and housing this stack in a housing (not shown). . The pressurized fluid to be processed is filtered by the filter material 2, and the purified fluid is taken out from the flow path of the shaft material 9 through the through hole 10 of the core fitting 7.

The filter medium 2 is formed by pressing a powder of a sinterable material such as metal or ceramic, or a fiber into a predetermined shape and sintering it. In this embodiment, the disk-shaped substrate portion 1 is formed.
A flange portion 14 that is parallel to the substrate portion 13 is formed on the outer peripheral portion 3 of the sheet 3 through a curved portion that bends toward the opposite side.
In addition, on one surface side of the substrate portion 13, that is, on the inner surface that is the opposite side, a convex support portion 15 that projects toward the opposite side is integrally formed. Further, the support portion 15 continuously extends radially from a position spaced a small distance m from the inner peripheral surface of the through hole 5 in the outer peripheral direction, and has a cross section of an arcuate curved surface, for example, an elongated slanting shape. In the body, the filter medium 2 is provided with a plurality of supporting portions 15 on its inner surface at equal intervals. In this way, when the support portions 15 are radially directed toward the flow direction of the filtered liquid, the flow resistance of the filtered target fluid can be reduced,
Allows smooth outflow and reduces pressure loss.

Further, the support portion 15 has a height which comes into contact with the inner surface of the other filter medium 2 when assembled as a filter, in this example,
The height h between the base plate portion 13 and the flange portion 14 is approximately 2
It has a height H about twice as high. In this embodiment, the filter medium 2a,
2b is the same body, one filter medium 2a is the other filter medium 2
half pitch p / of the circumferential interval of the support portion 15 with respect to b
By arranging 2 so as to be displaced, the supporting portion 15 of the one filter medium 2a is made to enter the gap between the supporting portions 15 of the other filter medium 2b, and between the supporting portions 15 that are adjacent to each other. A flow passage for the fluid to be processed is formed.

When the filter 1 is for filtering molten polymer, a thin disk-shaped porous body having an inner diameter of 55 mm, an outer diameter of 140 mm and a thickness (t) of 2 mm is used as the filter medium 2. Further, in the filter medium 2 of FIG. 1, since the support portion 15 is a continuous body having substantially the same width w, the circumferential cross sections near the inner peripheral portion 4 and the outer peripheral portion 3 are shown in FIGS. The flow channel width G between the support portions 15 changes. In this embodiment, the flow channel width (spacing) (Gi) on the inner peripheral side is 1.5 mm, and the flow channel width (Go) on the outer peripheral side is about 6 mm. . 2 for each filter medium 2
In the present embodiment in which 0 support portions 15 are formed and are radial continuous bodies, the circumferential width w of the support portions 15 is, for example, 2 to 15 mm, and the height H is set to a cross-sectional dimension of about 2 to 20 mm. It is preferable to form a flow path having a thickness of at least 1 mm between the supporting portions 15.

The specific specifications of the filter medium 2 are set in consideration of the filter characteristics, the properties of the object to be treated, the filtration conditions such as the working pressure, and the supporting portion 15 has two overlapping filter mediums 2a and 2b. It is formed to have a strength capable of withstanding the external filtration pressure acting on the outer surface and retaining the shape of the filtration chamber 12.

Further, when the support portion 15 is a radial continuum, the flow passage width G between the support portions 15 becomes wider on the outer peripheral portion 3 side, so that the support strength of the support portion 15 may be insufficient. It is possible to compensate for the lack of support strength by the support portion 15 by widening the portion 15 toward the outer peripheral portion 3 side or by adding a support portion that does not collide due to the orientation in addition to the support portion formed of a continuous body. Although the inner peripheral portion 4 side becomes narrower, since the filter medium 2 is a porous sintered member, it is possible to suppress an increase in pressure loss when the fluid to be processed flows through to the center side, and for this reason, the support is provided. The density of the portion 15 can be coarse. In addition, the flow-through direction is the outer peripheral portion 3.
It is also possible to close the inner peripheral side 4 so as to face

Further, the supporting portion 15 can be, for example, meandering or curved in one direction, in addition to the linear shape as shown in FIG. 1, and instead of being continuous, for example, a hemispherical small projection is formed on the entire surface. It is possible to adopt various forms such as evenly arranging them, or to appropriately mix the long and short continuous bodies and the supporting portions 15 composed of small projections. Further, the support portion 15 can have various cross-sectional shapes such as a trapezoidal shape having a flat upper surface with a chamfered cross section.

The filter medium 2 is a porous member obtained by molding a sinterable powder material such as metal or ceramic, or a fiber material containing short fibers into a predetermined shape and sintering it, as described above, such as nickel and titanium. Of metal, their alloys, especially stainless steel and other corrosion resistant materials,
Although it has excellent strength and corrosion resistance and is relatively easy to mold, for a stainless steel filter medium, for example, Japanese Patent Publication No. 3-333.
No. 70 has a fiber diameter of 2 to 20 μm and an aspect ratio of 1 to 50.
It is proposed to press-sinter the stainless steel short fiber of (3) under pressure so as to have a predetermined characteristic. For example, as the filter medium 2 of the present invention, the proposed sintered filter medium can be used depending on the purpose.

FIG. 5 shows a porous distribution state of the support portion 15 obtained by cutting the support portion 15 of the filter medium described in (specific example) along the line AA in FIG. 1 and magnifying it 17 times. In the substrate portion 13 of the filter medium 2, the average density of the support portion region 15a in which the support portion 15 is formed is made coarser than the average density of the non-support portion region 15b in which the support portion 15 is not provided. In such a density distribution state, when the fine powder to be filled in the mold is pressed, the non-supporting portion region 15b has a larger depression rate than the supporting portion region 15a, and therefore the non-supporting portion region 15b. It can be inferred that the average density at

The stainless steel atomized powder shown in FIG. 5 is pressed at a predetermined pressure. For example, the distribution density of the powder is about 60 to 65% in the supporting portion region 15a, while it is in the non-supporting portion region 15b. It is 63 to 68%, and changes gently during that period. However, if the density difference is increased more than necessary, the instability as a filter becomes large. Therefore, it is preferable to set the density difference to about 8% or less. The average density is shown as a value measured at three points of the ratio of the pore area to the visual field area in the cross section cut at a right angle to the filter surface by a method such as image analysis with a microscope.

Therefore, when such a filter medium having filter surfaces having different distribution densities is used, the supporting portion region 15a is formed.
Although the filtrate flows through the coarse pores relatively easily in the above, the flow-through distance becomes long and acts as so-called deep layer filtration, whereas in the non-supporting portion region 15b, the pores themselves are dense. As a result, it acts as a surface filtration, a homogeneous filtration property which is well balanced as a whole is obtained, and the reduction of the effective filtration area can be prevented.

Further, by making the density of the supporting portion region 15a coarser than that of the non-supporting portion region 15b, it is assumed that when the filtered processing fluid in the filtration chamber 11 flows out, it is supposed to pass through again. However, since the pores at that portion are rough, the rise in flow resistance can be suppressed. Both filter media 2, 2
In the case of alternately arranging the supporting portions 15 of the above, the non-supporting portion region 15b of the filter medium that is in contact with the rough supporting portion region 15a is dense and excellent in strength, and even when supporting a high filtration pressure, Damage can be reduced. In addition, in order to obtain a desired pore distribution characteristic, for example, a molding die in which the pressing ratio is partially different, such as the supporting portion region 15a and the non-supporting portion region 15b, can be used.

It should be noted that the outer peripheral portion 3 is joined to the filter media 2 and 2,
The filter medium 2 and the core fitting 15 can be joined by using, for example, laser welding or electron beam welding in which the melting range is small.

FIG. 6 shows another example of the sintered filter 1 of the present invention, in which a spacer metal member 17 is interposed for joining the outer peripheral portion of the filter medium 2, and the supporting portion 15 is provided in the filter chamber 12. The filter media 2 and 2 are supported to each other by making the height smaller than the height of the filter and contacting the end faces thereof. Further, for example, only one of the filter members has such a supporting portion 15
Alternatively, the other filter medium 2 may be a flat plate having no supporting portion 15.

In the filter 1 of the present invention, the supporting portion 1
Since 5 is integrally formed of the same material as a part of the filter medium 2, the number of parts can be reduced and the process can be shortened.
It is possible to eliminate peeling of the support portion 15. Moreover, the support portion 15
Also, since the density is relatively rough together with the support portion region 15a, the flow resistance in the support portion 15 can be suppressed, and the problems of retention and pressure loss are improved. Further, the filter medium 2 has been described as a single layer integrally formed with the supporting portion, but this single layer body has a fine layer (not shown) having fine pores as necessary.
It is also possible to form a laminated structure in which It is also possible to form a rod-shaped porous body only for the support portion 15 in advance, and then stack it on a flat plate-shaped filter medium and sinter it to form an integral structure.

(Concrete example) A stainless steel atomized powder (200 mesh under) was filled in a predetermined mold, and 50
Press at 0T and sinter at 1100 ° C to obtain an outer diameter of 1
40mm, inner diameter 55mm, thickness 2mm, forming a convex filter medium with a radial support of 6mm width and 4mm height on one side,
The two pieces were made to face each other, and the outer peripheral portion was welded to produce an example product. In this filter, a total of 20 support portions are arranged at equal intervals, and the cross-sectional shape thereof has a smooth arc shape as shown in FIG.

On the other hand, the filter of the comparative example is a flat plate-like filter material molded to the same size with the above-mentioned stainless steel powder.
A conventional coarse mesh or a punching plate with concavo-convex shape is used.

The mesh structure is as follows.

Comparative Example 1 1.6φ × 4 mesh (pressurized to a thickness of 2.8 mm) Comparative Example 2 1.6φ × 7 mesh (pressurized to a thickness of 2.8 mm) Comparative Example 3 Punching plate (t: 0 .8 5φ x 8
mm pitch) embossed concavo-convex molding.

In order to compare the filtration characteristics of these four types of leaf filters, a unit resin PET resin (model number: MA-2103, melting point: 251 ° C., specific gravity: 1.
No. 38) was used and evaluated by a GT-40-24A type filtration test device manufactured by Plastic Optical Laboratory Co., Ltd.
The test conditions are such that the resin is heated and melted at 275 ° C.
The flow rate was 5 kg / Hr, and the pressure loss was measured for each flow rate.

The results are shown in FIG. 7, and as is clear from the results, the pressure loss of the filter medium of the present invention is smaller than that of the comparative filter at any flow rate, and particularly, as a conventional retainer. It was possible to achieve an improvement of about 20% compared to the coarse mesh used.

[0035]

As described above, in the invention described in claim 1, the pressure resistant member such as the mesh can be omitted, the increase of filtration resistance can be suppressed, and the filtration quality can be improved.
And productivity can be improved.

The invention according to claim 2 enables uniform filtration, and the invention according to claim 3 can prevent retention of the filtered fluid and reduce generation of gel and the like.

[Brief description of drawings]

FIG. 1 is a plan view illustrating one embodiment of the present invention.

FIG. 2 is a sectional view thereof.

FIG. 3 is a cross-sectional view of an inner peripheral portion side of the support portion of FIG.

FIG. 4 is a cross-sectional view of an outer peripheral side of the support section of FIG.

FIG. 5 is an enlarged cross-sectional view showing a support portion.

FIG. 6 is a cross-sectional view illustrating another form.

FIG. 7 is a diagram showing an example of a filtration test result.

[Explanation of symbols]

2 filter media 3 outer periphery 4 inner circumference 12 Filtration room 13 Board part 14 Flange 15 Support 15a support portion area 15b Unsupported area

Claims (3)

[Claims] 1. A sintered filter in which two thin plate-shaped filter media are superposed and one of the outer peripheral part and the inner peripheral part thereof is closed to form a filter chamber between the inner surfaces of the filter media. Sintering characterized in that a pressure-resistant structure capable of withstanding a predetermined external filtration pressure is provided by providing a support portion projecting to the opposite side on the inner surface of at least one of the filter media, and bringing the support portion into contact with the other filter media. filter. 2. The filter medium provided with the supporting portion is characterized in that the average density of the supporting portion region provided with the supporting portion is made coarser than the average density of the non-supporting portion region having no supporting portion. The sintered filter according to claim 1. 3. The sintered filter according to claim 1, wherein the support portion is formed by radially extending from a central portion of the filter medium in a radial direction.