Filter material, and filter for electric discharge machine using same, filter for wire-cut machine, electric discharge machining system, and method for manufacturing filter material

Abstract

To provide a filter medium which suppresses reduction in a life while increasing initial efficiency.SOLUTION: A filter medium includes a support layer, and a filter layer which is stacked on the support layer so that one surface is fixed to the support layer and the other surface is used as a filtration surface where a filtration object is accumulated. The filtration layer has a mesh finer than that of the support layer, the filtration layer contains a synthetic resin fiber, the support layer contains synthetic resins fiber and fibrillated lyocell fibers, a compounding amount of the lyocell fibers is 10-30 wt.%, and the above structure filters dust by the fibrillated lyocell fibers of the support layer until the dust is accumulated in the filtration layer and sufficient filtration performance is shown, and thereby can improve initial characteristics. A short life of a filter can be avoided by not increasing the compounding amount of the synthetic resin fibers of the filtration layer.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to a filter medium, a filter for an electric discharge machine using the same, a filter for a wire-cutting machine, an electric discharge machining system, and a method for manufacturing the filter medium. [Background technology]

[0002] Filter media are used for purposes such as efficiently removing and purifying solid particles contained in a medium such as a liquid. For example, in electrical discharge machines (EDMs) such as wire-cut EDMs, a filter is used to remove fine metal chips (also known as sludge or dust) from the workpiece (workpiece) during machining and mixed into the machining fluid. This filter media is made of folded synthetic fibers, cellulose, or other materials and packed into a cylindrical metal or resin container. Due to the increasingly fine cutting chips produced by these EDMs, a liquid filter with high initial efficiency (initial efficiency) is desired. To address this issue, liquid filters have been proposed with a two-layer structure consisting of a filtration layer and a support layer, with the upstream filtration layer containing fibrillated lyocell fibers (Patent Documents 1 to 6).

[0003] For example, Patent Document 2 states that by including fibrillated lyocell fibers in the filtration layer and quasi-filtration layer (support layer), high filtration performance (short filtration time until the obtained filtrate becomes transparent) can be achieved through internal filtration by the fibrillated lyocell fibers contained in the filtration layer and quasi-filtration layer until a certain amount of particles captured on the surface accumulates.

[0004] However, according to this patent document, in order to improve the initial performance of internal filtration, the filtration layer contains 40 to 90% by weight of fibrillated lyocell fibers, which causes the differential pressure to increase rapidly and shortens the lifespan of the filter material.

[0005] On the other hand, Patent Document 3 discloses a structure in which a filtration layer contains fibrillated lyocell fibers and a support layer that does not contain fibrillated lyocell fibers is provided downstream. In this case, there is a problem that the filtration function cannot be fully exerted until a certain amount of particles captured on the surface accumulates.

[0006] To address this issue, it has been considered to improve the initial performance of internal filtration by increasing the amount of fibrillated Lyocell fibers in the filtration layer. However, this approach has the problem of causing the filtration layer to become clogged, thereby shortening the filter's lifespan. In this way, improving the initial performance by increasing the amount of fibrillated Lyocell fibers and extending the filter's lifespan are contradictory properties, and it has been difficult to achieve both. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Patent No. 5727562 [Patent Document 2] Patent No. 4120737 [Patent Document 3] Patent No. 4086729 [Patent Document 4] Patent No. 5599071 [Patent Document 5] Patent No. 5599072 [Patent Document 6] Patent No. 5759435 Summary of the Invention [Problem to be solved by the invention]

[0008] An object of the present disclosure is to provide a filter medium that has high initial efficiency while suppressing a decrease in lifespan, and a filter for an electric discharge machine, a filter for a wire-cutting machine, an electric discharge machining system, and a method for manufacturing the filter medium that use the same.

[0009] According to a first aspect of the present invention, there is provided a filter medium comprising a support layer and a filtration layer laminated to the support layer so as to be fixed on one side thereof and having the other side as a filtration surface on which material to be filtered accumulates, the filtration layer having a finer mesh than the support layer, the filtration layer containing synthetic resin fibers, and the support layer containing synthetic resin fibers and fibrillated lyocell fibers, the content of the lyocell fibers being 10 to 30 wt %. With this configuration, until dust accumulates in the filtration layer and sufficient filtration performance is achieved, the fibrillated lyocell fibers in the support layer filter the dust, thereby improving the initial characteristics.

[0010] Further, according to a second aspect of the present invention, in the above-mentioned filter medium, the blending amount of the lyocell fibers is 18 to 30% by weight.

[0011] Furthermore, according to a third aspect of the present invention, in any one of the above aspects, the blending amount of the lyocell fibers is 10 to 20% by weight.

[0012] Furthermore, according to a fourth aspect of the present invention, in any one of the above aspects, the blending amount of the lyocell fibers is 18 to 20% by weight.

[0013] Furthermore, according to a fifth aspect of the present invention, there is provided a filter medium comprising a support layer and a filtration layer laminated so as to fix one surface to the support layer and having the other surface as a filtration surface on which the material to be filtered accumulates, wherein the filtration layer has a finer mesh than the support layer, the filtration layer contains synthetic resin fibers, the support layer contains synthetic resin fibers and fibrillated lyocell fibers, and the filter medium has a maximum pore size of 40 to 49 μm and a mean flow pore size of 25 to 35 μm.

[0014] Furthermore, according to a sixth aspect of the present invention, there is provided a filter medium in any one of the above aspects, wherein the filtration layer does not contain fibrillated lyocell fibers.

[0015] Furthermore, according to a seventh aspect of the present invention, in the filter medium of any one of the above aspects, the filtration layer further contains a pulp-like synthetic polymer.

[0016] Furthermore, according to the filter medium according to an eighth aspect of the present invention, in any of the above aspects, the initial efficiency is 85% or more at a particle size of 5 μm.

[0017] Furthermore, according to a ninth aspect of the present invention, in any one of the above aspects, the filter medium has a bending resistance of 700 mgf or more.

[0018] Furthermore, according to a filter for an electric discharge machine according to a tenth aspect of the present invention, the filter medium according to any one of the above aspects can be used.

[0019] Furthermore, according to a filter for a wire cut processing machine according to an eleventh aspect of the present invention, the filter medium according to any one of the above aspects can be used.

[0020] Furthermore, according to a twelfth aspect of the present invention, the electrical discharge machining system comprises a filter device having a filter material using the filter material according to any of the above aspects and a filter cartridge into which the filter material is inserted, a machining tank for storing machining fluid, an electrical discharge machining unit that performs electrical discharge machining in the machining fluid stored in the machining tank, a control unit that controls the machining operation of the electrical discharge machining unit, and a circulation path that connects the machining tank and the filter device so that the machining fluid circulates, and is configured so that the machining fluid discharged from the machining tank is filtered by the filter device and returned to the machining tank.

[0021] Furthermore, according to a thirteenth aspect of the present invention, there is provided a method for manufacturing a filter medium comprising a support layer and a filter layer laminated so as to fix one side to the support layer and having the other side as a filtering surface on which the material to be filtered accumulates, the method comprising the steps of: beating organic synthetic resin fibers and mixing them with synthetic resin fibers to form a filtering layer; mixing the synthetic resin fibers with 10 to 30% by weight of fibrillated lyocell fibers to form the supporting layer; and attaching the supporting layer to one side of the filtering layer to form an integral layer. [Brief explanation of the drawings]

[0022] [Figure 1] FIG. 2 is an enlarged cross-sectional view showing a filter medium according to an embodiment of the present invention. [Figure 2] 1 is a graph showing the relationship between the blending amount of Lyocell fiber and the initial efficiency and life of the filter media according to Examples 1 and 2 and Comparative Example 1. [Figure 3] 1 is a graph showing the relationship between the maximum pore size and the initial efficiency and life of the filter media according to Examples 1 and 2 and Comparative Example 1. [Figure 4] 1 is a graph showing the relationship between the mean flow pore size and the initial efficiency and life of the filter media according to Examples 1 and 2 and Comparative Example 1. [Figure 5] 1 is a graph showing the relationship between the amount of Lyocell fiber blended in the filter media according to Examples 3 to 7 and Comparative Example 3 and the initial efficiency. [Figure 6] FIG. 1 is a schematic diagram showing an electric discharge machining system. [Figure 7] FIG. 1 is a perspective view showing an example of a filter device. [Figure 8] FIG. 10 is a perspective view showing another example of a filter device. DETAILED DESCRIPTION OF THE INVENTION

[0023] Embodiments of the present invention will be described below with reference to the drawings. However, the embodiments described below are merely examples for embodying the technical concept of the present invention, and the present invention is not limited thereto. Furthermore, this specification in no way specifies the components set forth in the claims as components of the embodiments. The dimensions, materials, shapes, and relative positions of components described in the embodiments are not intended to limit the scope of the present invention, and are merely illustrative unless otherwise specified. The size and relative positions of components shown in the drawings may be exaggerated for clarity. Furthermore, in the following description, the same names and symbols indicate identical or similar components, and detailed descriptions will be omitted as appropriate. Furthermore, the elements constituting the present invention may be configured with the same components, so that one component serves multiple functions, or conversely, the functions of one component may be shared among multiple components.

[0024] The filter medium according to an embodiment of the present invention is a component for filtering a filtering object. Generally, it is used as a filter medium in a filter device. The filtering object varies depending on the application of the filter medium, and is called dust, sludge, or the like. The filter medium can be used, for example, in a filter device that filters wastewater in a machine tool such as a processing machine, an oil filter for an engine, or a septic tank.

[0025] Preferably, the filter is used as a filter for machinery and equipment that are subject to a certain period of downtime, such as a processing machine. For such equipment that is subject to downtime, the filter material that adheres to the filter material can be dropped by its own weight during periods when the equipment is not in use, such as at night, thereby preventing a decrease in filtering performance. That is, according to this embodiment, filtering performance can be restored during periods when equipment such as processing machines are not in use. This allows filtering performance to be restored during periods when the processing machine is not in use, without the need for a special maintenance period. Therefore, the user does not need to be particularly aware of the operation or time required for filtering performance recovery, and the filtering performance recovery process is performed autonomously. In this way, the filter's own characteristics allow dust to fall by its own weight, thereby preventing a decrease in pressure loss, extending the filter's lifespan, extending the time until replacement, and achieving the excellent effect of reducing maintenance effort and costs. According to this embodiment, the dust particles accumulated on the filter material surface can be released by promoting dust separation, restoring filtering performance, and preventing a decrease in filtering performance due to long-term use.

[0026] The filter medium according to this embodiment can be suitably used as a filter for an electric discharge machine, and in particular, as a filter for a wire-cut machine. [Embodiment 1]

[0027] A filter medium 10 according to an embodiment of the present invention is shown in the schematic cross-sectional view of Figure 1. The filter medium 10 shown in this figure includes a support layer 1 and a filtration layer 2. The support layer 1 supports the filtration layer 2. The filtration layer 2 is laminated so that one surface thereof is fixed to the support layer 1. The other surface of the filtration layer 2 serves as a filtration surface on which the material to be filtered accumulates. (Support layer)

[0028] The support layer contains synthetic resin fibers and fibrillated lyocell fibers, and the blending amount of the lyocell fibers is 10 to 30% by weight.

[0029] With this configuration, the initial characteristics can be improved by incorporating fibrillated lyocell fibers into the support layer to capture dust through internal filtration until sufficient filtration performance is achieved due to dust accumulation on the filtering surface. Furthermore, by setting the amount of lyocell fibers in the support layer to be equal to or less than the upper limit of the above range, the mesh size is not made excessively fine, and a shortened filter life can be avoided.

[0030] Specific examples of synthetic resin fibers in this specification include polyester-based resins, polyolefin-based resins, polyamide-based resins, acrylic-based resins, polyvinyl acetate-based resins, polyvinyl alcohol-based resins, polyphenylene sulfide-based resins, modified resins thereof, and mixtures thereof, and among these, polyester-based resins are preferably used.

[0031] The synthetic resin fiber may be a fiber made of a single resin, or a fiber made of two or more types of resin (composite fiber).Furthermore, a single type of fiber may be used, or a combination of multiple fibers may be used.

[0032] The synthetic resin fiber may be a fiber that functions as a heat-fusible binder. Specific examples include undrawn fibers and composite fibers such as core-sheath, sea-island, and side-by-side fibers made of multiple resins with different melting points.

[0033] The average width of the synthetic resin fibers is preferably 1.0 μm to 50 μm, more preferably 2.0 μm to 40 μm, and even more preferably 3.0 μm to 30 μm. The average fiber width can be determined, for example, by observing with a scanning electron microscope and finding the arithmetic mean value of the widths of 100 fibers randomly selected.

[0034] The blending amount of lyocell fiber is preferably 18 to 30% by weight. By making the blending amount equal to or greater than the lower limit of the above range, the initial efficiency of filtering finer particles can be improved.

[0035] Alternatively, the blending amount of lyocell fiber may be 10 to 20% by weight. By keeping the blending amount at or below the upper limit of the above range, the rigidity of the filter medium can be maintained high, and deformation and breakage during high-pressure filtration operation can be suppressed.

[0036] Alternatively, the blending amount of lyocell fiber may be 18 to 20% by weight.

[0037] The fiber length of the fibrillated lyocell fiber in the support layer is preferably about 4 mm. In this specification, the fiber length is measured using Contour (the path length of the center line of the fiber) before beating. A measuring device such as Kajaani FS300 (Metso) can be used. (filtration layer)

[0038] The filtration layer has a finer mesh than the support layer and includes synthetic resin fibers and a pulp-like synthetic polymer.

[0039] The content of synthetic resin fibers in the filtration layer 2 is not particularly limited, but is preferably 40% by mass to 90% by mass, more preferably 45% by mass to 80% by mass, and even more preferably 50% by mass to 70% by mass, which allows the filtration layer 2 to achieve both good filtering performance and strength.

[0040] The length of the synthetic resin fibers is not particularly limited, but is preferably 1.5 mm to 20 mm, more preferably 2.0 mm to 18 mm, and even more preferably 3.0 mm to 18 mm.

[0041] The filtration layer preferably further contains a pulp-like synthetic polymer. Specific examples of the pulp-like synthetic polymer include polyamide, polyimide, polyamideimide, polyacrylonitrile, polyester, polyolefin, polycarbonate, polyacetal, polybutylene terephthalate, ultra-high molecular weight polyethylene, polysulfone, polyethersulfone, polyphenylene sulfide, polyarylate, polyetherimide, polyetheretherketone, aromatic polyamide, aromatic polyimide, liquid crystal polymer, modified resins thereof, and mixtures thereof. The content of the pulp-like synthetic polymer is preferably 10 to 50%, more preferably 15 to 45%, and even more preferably 20 to 40%. This facilitates the removal of dust accumulated on the filtration surface.

[0042] The initial efficiency of the filter medium 10 is preferably 85% or more for particles of 5 μm in diameter. Here, the initial efficiency can be measured by the method specified in ISO19438:2003. Specifically, using a multi-pass filter tester conforming to the aforementioned standard, test oil and contaminant particles are passed through the filter medium, and contaminant particles of any particle size are counted upstream and downstream of the filter medium. The filtration efficiency is calculated using the following formula, and is the average value 4, 5, and 6 minutes after the start of the test. (Formula 1) (Filtration efficiency) = (Upstream count - Downstream count) / (Upstream count) x 100 (%)

[0043] This allows a clear filtrate to be obtained in a short time even when filtering a liquid containing fine dust.

[0044] The bending resistance of the filter medium 10 is preferably 700 mgf or more, and more preferably 850 mgf or more. (Other ingredients)

[0045] The filter medium 10 may contain components other than those described above. Examples of such other components include binders, flocculants, plasticizers, colorants, antioxidants, UV absorbers, light stabilizers, softeners, modifiers, rust inhibitors, fillers, surface lubricants, corrosion inhibitors, heat stabilizers, lubricants, primers, antistatic agents, polymerization inhibitors, crosslinking agents, catalysts, leveling agents, thickeners, dispersants, antioxidants, flame retardants, hydrolysis inhibitors, corrosion inhibitors, carbon fibers, carbon nanotubes, carbon nanofibers, fullerenes, metal fibers, and metal particles.

[0046] The thickness of the filter medium 10 is not particularly limited, but is preferably 50 μm to 400 μm, more preferably 55 μm to 370 μm, and even more preferably 60 μm to 350 μm.

[0047] The volume ratio of the support layer to the entire filter medium 10 is preferably 30% by volume or more and 90% by volume or less, more preferably 40% by volume or more and 85% by volume or less, and even more preferably 50% by volume or more and 82% by volume or less.

[0048] Examples of materials that can be used for the support layer 1 include dry nonwoven fabrics, wet nonwoven fabrics, woven fabrics, etc., such as meltblown, spunlace, and needle punch. Of these, wet nonwoven fabrics are preferred in terms of adhesion to the filtration layer. (Method of manufacturing filter medium 10)

[0049] Here, a method for manufacturing such a filter medium 10 will be described. However, the contents of the present invention are not limited to the following examples.

[0050] The filter layer can be preferably manufactured by a wet papermaking method. First, a pulp-like synthetic polymer and synthetic resin fibers are dispersed in water to form a papermaking slurry. Next, the water is filtered through a wire mesh of a papermaking machine and dried using a cylinder dryer or the like to obtain a filter layer. The papermaking machine can be a fourdrinier, cylinder, inclined short-wire, twin-wire, or other type.

[0051] Next, 10 to 30% by weight of fibrillated lyocell fibers are mixed with the synthetic resin fibers to form a support layer. The mixing method can be to impregnate or coat a base fabric made of synthetic resin fibers with a lyocell fiber dispersion, or it can be made into a paper similar to the filtration layer. The support layer is then attached to one side of the filtration layer to form an integrated laminate. The attachment method can be to blend a heat-sealable binder fiber into both or one of the support layer and filtration layer, and then heat and press the laminate using a cylinder dryer or the like, or to laminate a heat-sealable mesh or the like between them. This results in a filter medium 10, in which a filtration layer 2 is laminated on a support layer 1, as shown in Figure 1. [Examples 1 and 2, Comparative Examples 1 and 2]

[0052] Next, filter media according to Examples 1 and 2 and filter media according to Comparative Examples 1 and 2 were prepared, and their properties were compared. The preparation method for each sample was as follows. First, as the material for the filtration layer, core-sheath polyester fiber (2.2 dtex, 5 mm), stretched polyester fiber (0.3 dtex, 5 mm), and acrylic pulp were dispersed in water at the blending ratios shown in Table 1 to form a papermaking slurry, which was then made into paper using a cylinder paper machine. On the other hand, as the material for the support layer, core-sheath polyester fiber (2.2 dtex, 5 mm), stretched polyester fiber (0.3 dtex, 5 mm), and beaten lyocell fiber were dispersed in water at the blending ratios shown in Table 1 to form a papermaking slurry, which was then made into paper using a Fourdrinier paper machine. The filtration layer and support layer were laminated in a wet paper state and dried using a Yankee dryer to obtain the filter media according to Examples 1 and 2 and Comparative Example 1.

[0053] In Comparative Example 2, the filter layer was made of a sheath-core polyester fiber (2.2 dtex, 5 mm), a stretched polyester fiber (0.3 dtex, 5 mm), and beaten lyocell fiber in the blending ratios shown in Table 1, the support layer was made of a sheath-core polyester fiber (2.2 dtex, 5 mm) and a stretched polyester fiber (0.3 dtex, 5 mm) in the blending ratios shown in Table 1, and the support layer was made using an inclined short-wire papermaking machine. Except for this, a filter medium according to Comparative Example 2 was obtained in the same manner as in Example 1. For each sample obtained, the basis weight, paper thickness, density, air permeability, maximum and median pore size (PS), flexibility, initial efficiency, and life were measured.

[0054] The basis weight of each sample was measured in accordance with JIS P 8124:2011.

[0055] The paper thickness of each sample was measured in accordance with JIS P 8118:2014.

[0056] The maximum pore size and mean flow pore size of each sample were measured using the bubble point method (ASTM F316-86, JIS K 3832) with 2-propanol as the test liquid. The mean flow pore size was determined by measuring the relationship between the differential pressure applied to the membrane and the air flow rate through it, both when the membrane was dry and when it was wet. The resulting graphs were designated the dry and wet curves, respectively. The differential pressure at the intersection of the dry curve (half the flow rate) and the wet curve was defined as P (Pa). This is the value of d (μm), expressed as d = cγ / P (where c is a constant and γ is the surface tension of the liquid in dynes / cm). The maximum pore size was determined by defining P (Pa) as the pressure at which bubbles first began to emerge from the liquid-wet sample (the bubble point value).

[0057] The bending resistance of each sample was measured using a Gurley tester in accordance with JIS L 1096:2010, with three 88.9 x 25.4 mm samples stacked together, and the measured value (mN) was converted to the bending resistance (mgf).

[0058] The initial efficiency and life of each sample were measured using a multi-pass filter test device conforming to ISO19438:2003, with a filtration area of ​​98.5 cm. 2 Measurements were taken at an oil volume of 6 L, a test flow rate of 0.7 L / min, and a concentration of 42.9 mg / L. Here, life is defined as the test time (minutes) from the start of the test until the filter pressure loss increases by 100 kPa.

[0059] The composition and physical properties of each sample are shown in Table 1. The relationship between the amount of Lyocell fiber in each sample and the initial efficiency and lifespan is shown in the graph in Figure 2. In the figure, ● indicates initial efficiency, and ▲ indicates lifespan. Furthermore, the relationship between pore size (maximum value), initial efficiency, and lifespan is shown in Figure 3, and the relationship between mean flow pore size, initial efficiency, and lifespan is shown in Figure 4.

[0060] [Table 1]

[0061] As shown in Table 1, in Examples 1 and 2, the initial efficiency was higher than that of Comparative Examples 1 and 2 as the amount of lyocell fiber in the support layer increased for all sizes of 4 μm or more, 5 μm or more, and 6 μm or more. Furthermore, the life decreased slightly as the amount of lyocell fiber increased, but remained at a higher level than that of Comparative Example 2. This is presumably because the surface of the upstream filtration layer traps dust particles to prevent clogging of the pores in the filter medium, while the fibrillated lyocell fibers arranged on the support layer side trap particles, improving the initial properties. [Examples 3 to 7, Comparative Example 3]

[0062] In addition, filter media according to Examples 3 to 7 and filter media according to Comparative Example 3 were each produced, and their properties were compared. The production method for each sample was the same as that of Example 1 above, except that the filtration layer and support layer were each made using a square sheet machine conforming to JIS P 8222, laminated in a wet paper state, and dried at 120°C using a rotary dryer manufactured by Kumagai Riki. The basis weight, paper thickness, and initial efficiency of each obtained sample were measured in the same manner as in Example 1. The composition and physical properties of each sample are shown in Table 2. The relationship between the blending amount of lyocell fiber and initial efficiency is shown in the graph of Figure 5.

[0063] [Table 2]

[0064] As shown in these tables and graphs, in Examples 3 to 7, a high correlation was observed between the amount of lyocell fiber blended in the support layer and the initial efficiency.

[0065] The filter material of the present embodiment can be preferably used as the filter material for electric discharge machine, more preferably as the filter material for the filter device of wire-cutting machine.In particular, it can be preferably used as the filter material for the filter device of the electric discharge machine such as wire-cutting electric discharge machine, which removes the fine metal chips of the workpiece that are discharged during machining and exist in the machining fluid.In this case, the object to be filtered is the fine metal chips. (Electrical Discharge Machining System 1000)

[0066] FIG. 6 shows an electric discharge machining system 1000 in which an electric discharge machine 200 and a filter device 100 are connected. The electric discharge machining system 1000 shown in this figure is connected to the electric discharge machine 200 and the filter device 100. The electric discharge machine 200 includes a machining tank 210 for storing machining fluid, an electric discharge machining unit 220 that performs electric discharge machining in the machining fluid stored in the machining tank 210, a control unit 230 that controls the machining operation of the electric discharge machining unit 220, and a circulation path 240 that connects the machining tank 210 and the filter device 100 so that the machining fluid circulates. The electric discharge machine 200 is connected so that water is discharged through the filter device 100. The electric discharge machining system 1000 is configured so that the machining fluid discharged from the machining tank 210 is filtered by the filter device 100 and returned to the machining tank 210.

[0067] The control unit 230 also controls the electric discharge machining unit 220 to stop the machining operation for a certain period of time. With this configuration, when the electric discharge machine 200 is not in use, such as at night, the filtering object adhering to the filter for the electric discharge machine 200 falls by its own weight, thereby suppressing a decrease in filtering performance. (Filter device 100)

[0068] The filter device 100 includes a filter cartridge 120 into which a filter material 110 is inserted. The filter material 110 is held in a vertical position with the filtering surface facing upright. An example of a filter device 100 connected to an electric discharge machine 200 is shown in FIG. 7 . The filter device 100 shown in this figure has a cylindrical filter cartridge 120 into which a filter material 110, made of a filter material 10, is inserted. This filter device 100 is placed vertically and uses an out-in system, in which wastewater is taken in from the circumferential direction, filtered by the filter material 110, and discharged axially, as indicated by the band-shaped arrows. In this filter device 100, wastewater containing dust DT is circulated through a circulation path 240 while the electric discharge machine 200 is operating. The wastewater is filtered by the filter device 100, purified, and made reusable.

[0069] Meanwhile, in the filter device 100, dust DT accumulates on the filtering surface of the filter material 110 due to the circulation of wastewater. In a filter device 100 for such a processing machine, dust DT, such as processing debris, adheres to the surface of the filter material 110 and forms a cake layer, which remains and reduces filtering performance. As the processing machine is used, the amount of dust DT that adheres increases, reducing pressure loss and eventually reaching the end of the filter device 100's lifespan.

[0070] For this reason, in order to extend the life of the filter device, conventional filter devices for processing machines have adopted a structure in which dust adhering to the surface of the filter material is sifted off by mechanical action, such as blowing compressed air to cause it to fall downward or vibrating the filter itself. However, adding a compressed air blowing mechanism to the filter device requires the preparation of a compressor, piping, etc., making the configuration complicated. Furthermore, a configuration that vibrates the filter material also requires the installation of a power mechanism to generate such mechanical action, which is similarly time-consuming. Furthermore, in either case, tasks such as blowing compressed air and vibrating the filter material must be repeated regularly, which creates the problem of additional maintenance work.

[0071] In contrast, the filter medium according to this embodiment does not require such an additional mechanism; instead, the characteristics of the filter medium 110 itself allow the adhering dust DT to fall under its own weight, allowing the dust DT to fall and settle to the bottom of the filter cartridge 120 at night or during downtime, without requiring any special operations, thereby restoring the filtering performance of the filter medium 110. This method allows existing filter devices to be used as is, eliminating the cost of application. Furthermore, there is no need to perform separate, regular operations to remove dust (such as spraying compressed air or vibrating the filter), making maintenance easy.

[0072] That is, according to this embodiment, by using a filter material with a smooth surface as a filter, dust DT and other particles adhering to the filter surface fall to the bottom of the filter cartridge 120 under their own weight, which is expected to restore filtering performance. In particular, for processing machines that require operational shutdowns, the dust falls during the shutdown period, improving the filtering performance recovery effect. A temporary shutdown is sufficient. That is, dust is expected to fall over time, even if it is not a long period such as several days or months. Furthermore, after a certain period, the filtering performance recovery effect is likely to saturate, as most of the dust will have fallen. The shutdown period varies depending on the processing volume of the processing machine used, the material and size of the workpiece, the type of filtrate, the size of the filter, and other factors. Tests conducted by the inventors have found that a shutdown period of approximately five hours is sufficient to restore filtering performance.

[0073] The filter of such a processing machine is generally replaced when the pressure loss of the filter reaches a specified value (for example, 200 kPa to 300 kPa). In other words, the life of the filter is determined by the time it takes to reach the specified pressure loss.

[0074] Furthermore, according to this embodiment, dust particles accumulated on the surface of the filter material fall to the bottom of the filter cartridge 120 during periods when the processing machine is stopped, reducing the resistance to fluid flow through the filter material. This suppresses an increase in pressure loss, lengthens the period until the specified value is reached, and extends the life of the filter. In other words, the filter material according to this embodiment is suitable for use in processing machines that are shut down for a certain period of time or longer. By utilizing the machine's downtime, the amount of dust that falls under its own weight is increased compared to the amount of dust that accumulates, thereby restoring filtration performance. This method allows for a filtration performance recovery period to be set during normal operation without any special steps or treatments, thereby lengthening the replacement cycle of the filter device. (filtration method)

[0075] Here, a filtration method using a filter device that uses the filter media according to this embodiment as the filter material will be described. Machining is performed using an electric discharge machine 200 equipped with an electric discharge machine filter, and materials to be filtered contained in the machining water are allowed to adhere to the surface of the electric discharge machine filter. Then, while the machining operation of the electric discharge machine 200 is stopped for a certain period of time or longer, the materials to be filtered that have adhered to the electric discharge machine filter are allowed to fall under their own weight. This allows the materials to fall under their own weight when the electric discharge machine 200 is not in use, such as overnight, and reduces degradation of filtering performance.

[0076] The shape of the filter device is not limited to the form shown in Fig. 7, and any known form can be used as appropriate. For example, a filter device 100' according to embodiment 2 may be configured as a plurality of flat plates extending radially around the periphery, as shown in Fig. 8. The filter device 100' shown in this figure also has a filter material 110' inserted into a filter cartridge 120'. [Industrial Applicability]

[0077] The filter material according to the present invention, and the filter for an electric discharge machine, the filter for a wire-cut machine, the electric discharge machining system, and the method for manufacturing the filter material can be suitably used as a filter material for a filter device for a machine such as a wire-cut machine. [Explanation of symbols]

[0078] 1…Support layer 2…filtration layer 10...filter medium 100, 100'...filter device 110, 110'...filter material 120, 120'...Filter cartridge 200…Electric discharge machine 210…Processing tank 220…Electric discharge machining department 230...Control unit 240...Circulation route 1000... Electrical discharge machining system DT...Dust

Claims

1. The supporters and a filtration layer having one surface laminated on the support layer so as to be fixed thereto, and the other surface serving as a filtration surface on which the material to be filtered accumulates; A filter medium comprising: The filtration layer has a finer mesh than the support layer, The filtration layer contains synthetic resin fibers, The filter medium wherein the support layer contains synthetic resin fibers and fibrillated lyocell fibers, and the blending amount of the lyocell fibers is 10 to 30% by weight.

2. The filter medium according to claim 1, The filter medium has a blending amount of the lyocell fiber of 18 to 30% by weight.

3. The filter medium according to claim 1, The filter medium has a blending amount of the lyocell fiber of 10 to 20% by weight.

4. The filter medium according to claim 1, The filter medium has a blending amount of the lyocell fiber of 18 to 20% by weight.

5. The supporters and a filtration layer having one surface laminated on the support layer so as to be fixed thereto, and the other surface serving as a filtration surface on which the material to be filtered accumulates; A filter medium comprising: The filtration layer has a finer mesh than the support layer, The filtration layer contains synthetic resin fibers, The support layer includes synthetic resin fibers and fibrillated lyocell fibers, The filter medium has a maximum pore size of 40 to 49 μm and a mean flow pore size of 25 to 35 μm.

6. The filter medium according to any one of claims 1 to 5, A filter medium in which the filtration layer does not contain fibrillated lyocell fibers.

7. The filter medium according to any one of claims 1 to 6, The filter medium, wherein the filtration layer further comprises a pulp-like synthetic polymer.

8. The filter medium according to any one of claims 1 to 7, A filter medium having an initial efficiency of 85% or more at a particle size of 5 μm.

9. The filter medium according to any one of claims 1 to 8, A filter medium having a bending resistance of 700 mgf or more.

10. A filter for an electric discharge machine using the filter material according to any one of claims 1 to 9.

11. A filter for a wire cutting machine using the filter material according to any one of claims 1 to 9.

12. A filter material using the filter material according to any one of claims 1 to 9, a filter cartridge into which the filter material is inserted; a filter device comprising: a machining tank for storing machining fluid; an electric discharge machining unit that performs electric discharge machining in the machining fluid stored in the machining tank; a control unit that controls the machining operation of the electric discharge machining unit; a circulation path that connects the machining tank and the filter device so that the machining fluid circulates; Equipped with The electric discharge machining system is configured so that the machining fluid discharged from the machining tank is filtered by the filter device and returned to the machining tank.

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