Filter material, a filter for an electrical discharge machining machine using the same, a filter for a wire cutting machine, an electrical discharge machining system, a method for manufacturing the filter material, and a filtration method using an electrical discharge machining machine filter.

Abstract

To suppress degradation in filtration performance and achieve long life of a filter.SOLUTION: A filter medium 10 includes a support layer 1, and a filtration layer 2 which is laminated with one surface fixed to the support layer 1 and the other surface as a filtration surface on which a filtration object is accumulated. The filter medium 10 contains Lyocell fibers and synthetic fibers having fiber length of 1 mm to 3 mm. Due to the structure, the surface of the filter medium 10 is smoothened, particles are likely to fall from the surface of the filter medium 10 by own weight when the filter medium 10 is in a vertical attitude and an oblique attitude, and degradation in filtration performance due to accumulation of the filtration object can be suppressed.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a filter medium, a filter for an electric discharge machine using the same, a filter for a wire cut machine, an electric discharge machining system, a method for manufacturing a filter medium, and a filtering method using a filter for an electric discharge machine.

Background Art

[0002] Filter media are used for applications such as efficiently removing solid particles contained in a medium such as a liquid and purifying it. For example, in an electric discharge machine such as a wire cut electric discharge machine, fine metal chips of the workpiece (also called sludge, dust, etc.) generated during the machining of the workpiece and mixed in the machining fluid are removed. To do this, a filter medium such as synthetic fiber or cellulose is folded, and a filtering filter in which this filter medium is packed in a cylindrical metal container or a cylindrical resin container is used (see, for example, Patent Document 1).

[0003] In such a filter, dust particles adhere over time and cause clogging, resulting in a decrease in filtering performance. Therefore, it must be replaced regularly. If the filter replacement frequency is high, it takes a lot of labor. In addition, since filters are generally expensive, there is a problem that it leads to an increase in running costs.

Prior Art Documents

Patent Documents

[0006] According to the first aspect of the present invention, the filter material comprises a support layer and a filter layer laminated so as to fix one side to the support layer and the other side being a filter surface on which the material to be filtered accumulates, wherein the filter material contains lyocell fibers and synthetic fibers having a fiber length of 1 mm to 3 mm. Furthermore, the lyocell fiber exhibits a distribution of mass-weighted average fiber length, with a first peak in the range of 1 mm to 3 mm and a second peak in the range of 0 mm to 1 mm. With the above configuration, the surface of the filter media is smoothed, making it easier for particles to fall off the surface of the filter media due to their own weight when the filter media is in a vertical or oblique position, thereby suppressing the decrease in filtration performance due to the accumulation of the material to be filtered.

[0007] Furthermore, according to the second aspect of the filter material, in addition to any of the above configurations, the smoothness of the filtration surface of the filter material can be made 0.6 seconds or more. With the above configuration, the surface of the filter material is smoothed so that when the filter material is in a vertical or oblique position, particles can easily fall off the surface of the filter material due to their own weight, thereby suppressing a decrease in filtration performance due to the accumulation of the material to be filtered.

[0008] Furthermore, according to the third aspect of the filter material, in addition to any of the above configurations, the arithmetic mean roughness (Ra) of the filtration surface of the filter material can be set to 12 μm or less. With the above configuration, the density of the filter material can be adjusted, reducing the amount of fuzz on the surface of the filter material, reducing the accumulation of the material to be filtered by the fuzz, promoting the separation of dust from the surface of the filter material, and thereby suppressing a decrease in filtration performance.

[0009] Furthermore, the filter material relating to the fourth aspect can be used as a filter for a processing machine that has a certain period of downtime, in addition to any of the above configurations. With the above configuration, when the electrical discharge machining machine is not in use, such as at night, the material to be filtered that adheres to the filter can fall off by its own weight, thereby suppressing a decrease in filtration performance.

[0010] Furthermore, according to the fifth aspect of the filter for electrical discharge machining, A filter for an electrical discharge machining (EDM) machine using a filter material, wherein the filter material comprises a support layer and a filter layer laminated so that one side is fixed to the support layer and the other side is a filter surface on which the material to be filtered accumulates, and contains lyocell fibers and synthetic fibers having a fiber length of 1 mm to 3 mm, and is configured so that the material to be filtered that adheres to the EDM machine filter falls off by its own weight while the machining operation of the EDM machine is stopped for a certain period of time. With the above configuration, when the electrical discharge machining (EDM) machine is not in use, such as at night, the material to be filtered that adheres to the EDM filter can fall off by its own weight, thereby suppressing a decrease in filtration performance.

[0011] Furthermore, according to the sixth aspect of the filter for the wire cutting machine, A filter for a wire cutting machine using a filter material, wherein the filter material comprises a support layer and a filter layer which is laminated so that one side is fixed to the support layer and the other side is a filter surface on which the material to be filtered accumulates, and contains lyocell fibers and synthetic fibers having a fiber length of 1 mm to 3 mm, and is configured so that the material to be filtered that adheres to the filter for the wire cutting machine falls off by its own weight while the processing operation of the wire cutting machine is stopped for a certain period of time. With the above configuration, when the wire cutting machine is not in use, such as at night, the material to be filtered that adheres to the EDM machine filter can fall off by its own weight, thereby suppressing a decrease in filtration performance.

[0012] Furthermore, according to the seventh aspect of the electrical discharge machining system, the system comprises a filter device having a filter material using any of the above-mentioned filter materials and a filter cartridge into which the filter material is inserted, a processing tank for storing processing fluid, an electrical discharge machining unit that performs electrical discharge machining in the processing fluid stored in the processing tank, a control unit that controls the processing operation of the electrical discharge machining unit, and a circulation path connected to the processing tank and the filter device so that the processing fluid circulates, wherein the processing fluid discharged from the processing tank is filtered by the filter device and recirculated back into the processing tank, the filter material is held in a position where the filtration surface is vertical, and the control unit can control the processing operation of the electrical discharge machining unit to be stopped for a certain period of time. With the above configuration, when the electrical discharge machining machine is not in use, such as at night, the material to be filtered attached to the filter for the electrical discharge machining machine can fall off by its own weight, thereby suppressing a decrease in filtration performance.

[0013] Furthermore, according to the eighth aspect of the method for manufacturing a filter material, the method for manufacturing a filter material comprises a support layer and a filter layer which is laminated so as to fix one side to the support layer and the other side is a filter surface on which the material to be filtered accumulates, wherein the fiber length is 1 mm to 3 mm Furthermore, the distribution of mass-weighted average fiber length shows a first peak in the range of 1 mm to 3 mm and a second peak in the range of 0 mm to 1 mm. The process may include steps of beating lyocell fibers and mixing them with synthetic fibers to form a filter layer, and attaching the support layer to one surface of the filter layer to integrally laminate it. This smooths the surface of the filter material, making it easier for particles to fall off the surface of the filter material due to their own weight when the filter material is in a vertical or oblique position, thereby suppressing a decrease in filtration performance due to the accumulation of the material to be filtered.

[0014] Furthermore, according to the ninth aspect of the filter media method, a support layer and a filter media that is laminated so as to fix one side to the support layer and the other side to which the material to be filtered accumulates are It contains lyocell fibers and synthetic fibers with a fiber length of 1 mm to 3 mm. A filtration method using a filter for an electrical discharge machining (EDM) machine, comprising the steps of: performing processing with an EDM machine equipped with the EDM machine filter, thereby causing the material to be filtered contained in the processed water to adhere to the surface of the EDM machine filter; and allowing the material to be filtered to fall off the EDM machine filter by its own weight while the EDM machine's processing operation is stopped for a certain period of time or longer. This allows the material to be filtered to fall off the EDM machine filter by its own weight while the EDM machine is not in use, such as at night, thereby suppressing a decrease in filtration performance.

[0015] Furthermore, according to the filtration method relating to the tenth aspect, in addition to the above, the aforementioned period can be set to 5 hours or more. [Brief explanation of the drawing]

[0016] [Figure 1] This is an enlarged cross-sectional view showing a filter material according to an embodiment of the present invention. [Figure 2] This graph shows the fiber length distribution of lyocell fibers before beating the filter material according to Example 1. [Figure 3] Figure 2 is a graph showing the fiber length distribution of lyocell fibers after beating. [Figure 4] It is a graph showing the fiber length distribution of the lyocell fibers before beating of the filter medium according to Comparative Example 1. [Figure 5] It is a graph showing the fiber length distribution of the lyocell fibers after beating in FIG. 4. [Figure 6] It is a graph showing the coarseness curve of the lyocell fibers in FIG. 2. [Figure 7] It is a graph showing the coarseness curve of the lyocell fibers in FIG. 4. [Figure 8] It is a schematic diagram showing an electric discharge machining system. [Figure 9] It is a perspective view showing an example of a filter device. [Figure 10] It is a perspective view showing another example of the filter device.

Mode for Carrying Out the Invention

[0017] Hereinafter, embodiments of the present invention will be described based on the drawings. However, the embodiments shown below are examples for embodying the technical idea of the present invention, and the present invention is not limited to the following. Also, this specification does not in any way identify the members shown in the claims with the members of the embodiments. In particular, the dimensions, materials, shapes, relative arrangements, etc. of the components described in the embodiments are not intended to limit the scope of the present invention only to those, but are merely illustrative examples. Note that the sizes and positional relationships of the members shown in each drawing may be exaggerated for clarity of explanation. Furthermore, in the following description, the same names and reference numerals indicate the same or equivalent members, and detailed descriptions will be omitted as appropriate. Furthermore, each element constituting the present invention may be configured such that a plurality of elements are constituted by the same member and one member serves as a plurality of elements, or conversely, the function of one member may be shared by a plurality of members and realized.

[0018] The filter material according to an embodiment of the present invention is a component for filtering a substance to be filtered. Generally, it is used as a filter material in a filter device. The substance to be filtered varies depending on the application of the filter material and is called dust, sludge, etc. The filter material can be used, for example, in a filter device for filtering wastewater in machine tools such as processing machines, in an oil element for an engine, or in a septic tank.

[0019] Preferably, it is used as a filter for machinery and equipment that have a certain period of inactivity, such as a processing machine. With equipment that has such an inactivity period, the amount of material to be filtered attached to the filter material can fall off by its own weight during the time the equipment is not in use, such as at night, thereby suppressing a decrease in filtration performance. In other words, according to this embodiment, the filtration performance can be restored by utilizing the inactivity period when the processing machine or other equipment is not in use. As a result, the filtration performance is restored during the period when the processing machine or other equipment is not in use, without having to set aside a special period for maintenance, so the user does not have to be particularly aware of the operation or time required to restore the filtration performance, and the process for restoring the filtration performance is performed autonomously. In this way, the dust falls off by its own weight due to the characteristics of the filter itself, thereby suppressing a decrease in pressure loss, extending the life of the filter, shortening the period until replacement, and achieving excellent effects such as reducing the effort and cost of maintenance. Thus, according to this embodiment, the detachment of dust particles accumulated on the surface of the filter material is promoted and the filtration performance is restored, thereby suppressing the decrease in filtration performance due to aging (details will be described later). [Embodiment 1]

[0020] A schematic cross-sectional view of a filter medium 10 according to an embodiment of the present invention is shown in Figure 1. The filter medium 10 shown in this figure comprises a support layer 1 and a filtration layer 2. The support layer 1 supports the filtration layer 2. support The filtration layer 2 is laminated so that one side is fixed to the support layer 1. The other side of the filtration layer 2 serves as the filtration surface where the material to be filtered accumulates.

[0021] The filter material 10 contains lyocell fibers and synthetic fibers having a fiber length of 1 mm to 3 mm. In this caseThe fiber length is measured using the Contour (path length of the fiber's centerline) in the state before beating. By using such fibers, the surface of the filter media 10 is smoothed, making it easier for particles to fall off the surface of the filter media 10 due to their own weight when the filter media 10 is in a vertical or oblique position, thereby suppressing the decrease in filtration performance due to the accumulation of the material to be filtered. Preferably, lyocell fibers with a fiber length of about 2 mm are used.

[0022] Furthermore, it is preferable that the smoothness of the filtration surface of the filter material 10 be 0.6 seconds or more. By doing so, the surface of the filter material 10 is smoothed so that when the filter material 10 is in a vertical or oblique position, the particles can easily fall off the surface of the filter material 10 due to their own weight. In this embodiment, the smoothness of the filter material 10 can be a value measured in accordance with JAPAN TAPPI Paper Pulp Test Method No. 5-2:2000.

[0023] Furthermore, it is preferable to set the arithmetic mean roughness (Ra) of the filtration surface of the filter media 10 to 12 μm or less. This adjusts the density of the filter media 10, reduces the amount of fuzz on the surface of the filter media 10, reduces the accumulation of the material to be filtered by the fuzz, promotes the separation of the dust from the surface of the filter media 10, and thereby suppresses a decrease in filtration performance. In this embodiment, the arithmetic mean roughness of the filter media 10 can be a value measured in accordance with JIS B0601.

[0024] Examples of synthetic fiber constituent materials include polyesters such as polyethylene terephthalate (PET), polybutylene terephthalate, and polylactic acid; polyolefins such as polyethylene and polypropylene; polyamides such as aromatic polyamides (aramid resins) such as poly-p-phenylene terephthalamide, and aliphatic polyamides such as nylon 6 and nylon 6,6; polyether ketones such as polyether ether ketone; thermoplastic resins such as acrylic resin, polyvinyl acetate, polyvinyl alcohol, polyphenylene sulfide, poly-p-phenylene benzoxazole, polyimide, polycarbonate, polystyrene, acrylonitrile-butadiene-styrene resin (ABS resin), polyvinyl chloride resin, and phenoxy resin; thermosetting resins such as epoxy resin, phenolic resin, melamine resin, and unsaturated polyester; copolymers of constituent monomers of these various resins (e.g., ethylene-vinyl alcohol copolymer), modified resins (e.g., maleic acid modified resin), and polymer alloys. One or more of these can be selected and used in combination. In particular, synthetic fibers made of polyethylene terephthalate (PET) are preferred.

[0025] The average length of the synthetic 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 16 mm. This allows the lyocell fibers to be more effectively retained in the filter layer 2, improving durability and reliability. It also allows for better flexibility of the filter material 10.

[0026] In the filter material 10 according to this embodiment, the average length of the fibers can be, for example, the arithmetic mean of the lengths of 100 fibers randomly selected by observation using a scanning electron microscope.

[0027] The average width of the synthetic fibers is preferably 1.0 μm or more and 50 μm or less, more preferably 2.0 μm or more and 40 μm or less, and even more preferably 3.0 μm or more and 30 μm or less.

[0028] In the filter material 10 according to this embodiment, the average width of the fibers can be, for example, the arithmetic mean of the widths of 100 fibers randomly selected by observation with a scanning electron microscope.

[0029] The synthetic fiber content in the filtration layer 2 is not particularly limited, but is preferably 7% to 90% by mass, more preferably 12% to 70% by mass, and even more preferably 18% to 50% by mass. This allows for a balance between the filtration performance and flexibility of the filtration layer 2. (Other ingredients)

[0030] The filtration layer 2 may contain components other than those mentioned 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, anti-aging agents, flame retardants, hydrolysis inhibitors, corrosion inhibitors, carbon fibers, carbon nanotubes, carbon nanofibers, cellulose nanofibers, fullerenes, metal fibers, metal particles, etc.

[0031] The thickness of the filtration layer 2 is not particularly limited, but is preferably 50 μm or more and 300 μm or less, more preferably 55 μm or more and 270 μm or less, and even more preferably 60 μm or more and 250 μm or less.

[0032] Furthermore, the filter media 10 may consist of multiple filtration layers. In this case, the filtration layers may be made of the same material and of similar thickness. Alternatively, they may be made of different materials and of different thicknesses.

[0033] The volume percentage of the filtration layer in the entire filter material 10 is preferably 30% to 90% by volume, more preferably 40% to 85% by volume, and even more preferably 50% to 82% by volume.。 Examples of materials that can be used as the support layer 1 include meltblown, spunlace, needle-punched dry nonwoven fabrics, wet nonwoven fabrics, woven fabrics, wire mesh, and sintered metal plates. Among these, dry nonwoven fabrics are particularly suitable due to their adhesion to the filtration layer. (Method for manufacturing filter material 10)

[0034] Here, we will explain how to manufacture such a filter material 10. However, the content of the present invention is not limited in any way to the following examples. First, lyocell fibers having a fiber length of 1 mm to 3 mm are beaten using a beating machine such as a double disc refiner, and filtered onto a wire mesh or the like to form a filter layer 2. Then, a support layer 1 is attached to one surface of the filter layer 2 to form an integral laminate. As a result, a filter material 10 is obtained in which the filter layer 2 is laminated on the support layer 1, as shown in Figure 1.

[0035] Here, as Example 1, the fiber length distribution of lyocell fibers with an average fiber length of 2 mm (contour) and an average fiber width of 18 μm before beating is shown in Figure 2, and the fiber length distribution after beating is shown in Figure 3. As a comparative example, the fiber length distribution of lyocell fibers with an average fiber length of 4 mm (contour) and an average fiber width of 16 μm before beating is shown in Figure 4, and the fiber length distribution after beating is shown in Figure 5. Furthermore, the roughness curve measured from the filtration surface of Example 1 is shown in Figure 6, and the roughness curve measured from the filtration surface of Comparative Example 1 is shown in Figure 7. A Metso kajaaniFS300 was used to measure these fiber lengths and fiber diameters. In addition, the filter material according to Example 1 had a filtration surface smoothness of 0.7 sec and an arithmetic mean roughness (Ra) of 11 μm. In contrast, the filter material according to Comparative Example 1 had a filtration surface smoothness of 0.5 sec and an arithmetic mean roughness (Ra) of 13 μm.

[0036] As shown in these figures, the lyocell fiber according to Example 1 has a peak fiber length that changes from 2 mm before beating to 1.8 mm after beating. m It can be confirmed that the fiber length has shifted by approximately m. Generally, it was found that the fiber length shifts to the shorter side by about 10% of the original length due to beating. In addition to these main peaks, there is also 0.3 mA small sub-peak was observed at approximately m. The main peak and sub-peak were clearly separated into two distinct peaks, as described in 1.8 above. m m and 0.3 m The distribution was relatively uniform across the two fiber lengths of m.

[0037] On the other hand, in the lyocell fiber of Comparative Example 1, the peak was increased by beating. m m to 0.5 m It changes significantly to about m, and there are also other peaks of 2-6 m The phenomenon occurred over a wide range of m, showing considerable dispersion and confirming that the fiber length was non-uniform. Furthermore, when a filter material using these lyocell fibers was prepared and tested in the filter device of a wire-cut electrical discharge machining machine described later, the filter material according to Example 1 showed a recovery of pressure loss during the shutdown period of the wire-cut electrical discharge machining machine, whereas the filter material according to the Comparative Example showed almost no change in pressure loss. This difference in the change in pressure loss can be interpreted as follows: In other words, the filter surface obtained by including lyocell fibers that have been finely milled to a uniform fiber length in Example 1 and the filter surface obtained by including lyocell fibers that have been finely milled to a non-uniform fiber length in Comparative Example 1 differ in their smoothness, as shown by the smoothness, surface roughness, and roughness curves described above. In Example 1, which has higher smoothness, the dust adhering to the filter surface fell off by its own weight during the shutdown period without the need for the mechanical operation described later, whereas in Comparative Example 1, the dust was deeply embedded in the irregularities of the filter surface and hardly peeled off. Thus, it was found that the filter material according to Example 1 has excellent properties as a filter material for a filter device of a wire-cut electrical discharge machining machine.

[0038] The filter material according to this embodiment can be suitably used as a filter material for an electrical discharge machining (EDM) machine, and more preferably as a filter material for a wire-cutting machine's filter device. In particular, it can be suitably used as a filter material for a filter device in an EDM machine, such as a wire-cutting EDM machine, to remove fine metal shavings from the workpiece that are discharged during processing and present in the processing fluid. In this case, the material to be filtered is fine metal shavings. (Electrical discharge machining system 1000)

[0039] Figure 8 shows an electrical discharge machining (EDM) system 1000 in which an EDM machine 200 and a filter device 100 are connected. The EDM system 1000 shown in this figure connects the EDM machine 200 and the filter device 100. The EDM machine 200 includes a machining tank 210 for storing machining fluid, an EDM section 220 that performs EDM machining in the machining fluid stored in the machining tank 210, a control unit 230 that controls the machining operation of the EDM section 220, and a circulation path 240 connected to the machining tank 210 and the filter device 100 so that the machining fluid circulates. The EDM machine 200 is connected to drain wastewater through the filter device 100. The EDM system 1000 is configured to filter the machining fluid discharged from the machining tank 210 with the filter device 100 and recirculate it back into the machining tank 210.

[0040] Furthermore, the control unit 230 controls the machining operation of the electrical discharge machining unit 220 to be stopped for a certain period of time. With this configuration, when the electrical discharge machining machine 200 is not in use, such as at night, the material to be filtered attached to the filter for the electrical discharge machining machine 200 can fall off by its own weight, thereby suppressing a decrease in filtration performance. (Filter device 100)

[0041] The filter device 100 comprises a filter cartridge 120 into which a filter material 110 is inserted. The filter material 110 is held in a position where its filtration surface is vertical. An example of a filter device 100 connected to an electrical discharge machining machine 200 is shown in Figure 9. In this figure, the filter device 100 has a cylindrical filter cartridge 120 into which a filter material 110 made of filter media 10 is inserted. This filter device 100 is stationary in a vertical position and, as indicated by the strip-shaped arrow, takes in wastewater from the circumferential direction, filters it with the filter material 110, and discharges the filtered water in the axial direction, using an out-in method. In such a filter device 100, while the electrical discharge machining machine 200 is in operation, wastewater containing dust DT is circulated through the circulation path 240. The wastewater is then filtered by the filter device 100, purifying it and making it reusable.

[0042] On the other hand, in the filter device 100, dust DT accumulates on the filtration surface of the filter material 110 due to the circulation of wastewater. In such a filter device 100 for a processing machine, dust DT such as processing debris adhering to the surface of the filter material 110 forms a cake layer and remains there, reducing the filtration performance. As the processing machine is used, the amount of such dust DT that adheres increases, reducing the pressure loss and leading to the end of the lifespan of the filter device 100.

[0043] Therefore, conventional filter systems for processing machines employed a structure that shook off dust adhering to the surface of the filter material by mechanical action, such as blowing compressed air to make it fall downwards or vibrating the filter itself, in order to extend the lifespan of the filter system. However, adding a compressed air blowing mechanism to a filter system requires the preparation of a compressor and piping, which complicates the configuration. Similarly, even in configurations that vibrate the filter material, it is necessary to provide a power mechanism to produce such mechanical action, which is also time-consuming. Furthermore, in either case, the operations of blowing compressed air or vibrating the filter material must be repeated and performed periodically, which adds to the maintenance effort.

[0044] In contrast, the filter material according to this embodiment does not require such an additional mechanism. The properties of the filter material 110 itself make it easy for the attached dust DT to fall off by its own weight. This allows the dust DT to fall and settle to the bottom of the filter cartridge 120 during nighttime or downtime without any special operation, thereby restoring the filtration performance of the filter material 110. With this method, existing filter devices can be used as is, and no additional costs are incurred for implementation. Furthermore, there is no need to perform dust removal operations (such as blowing compressed air or vibrating the filter) separately on a regular basis, resulting in excellent maintainability.

[0045] In other words, according to this embodiment, by using a filter material with a smooth surface as the filter, dust DT and other particles adhering to the filter surface fall to the bottom of the filter cartridge 120 by their own weight, and the filtration performance is expected to recover. Furthermore, in order to smooth and densify the surface of the filter material, as described above, lyocell fibers are used in the filter material, and the average fiber length is set to 1 mm to 3 mm, preferably about 2 mm. The inventors have found that this has the effect of promoting so-called dust detachment, where dust is separated from the filtration surface by its own weight alone. In particular, in the case of a processing machine that has to stop operating, such dust detachment progresses during the period when the machine is stopped, and the effect of recovering filtration performance improves. The stoppage of operation only needs to be temporary. That is, even if it is not for a long period of several days or several months, dust detachment can be expected over time. Also, after a certain period, the dust will have almost completely fallen off, and the effect of recovering filtration performance is expected to saturate. The stoppage period will vary depending on the processing capacity of the processing machine used, the material and size of the workpiece, the type of filtered water, the size of the filter, etc. According to tests conducted by the inventors, it was found that a rest period of approximately 5 hours is sufficient to restore filtration performance.

[0046] The filter replacement time for such processing machines is generally when the filter's pressure loss reaches a specified value (e.g., 200kPa to 300kPa). In other words, the filter's lifespan is determined by the time it takes to reach the specified pressure loss.

[0047] Furthermore, according to this embodiment, dust particles accumulated on the surface of the filter media fall to the bottom of the filter cartridge 120 during the processing machine's downtime, reducing the airflow resistance of the filter media. This suppresses the decrease in pressure loss, extends the time it takes to reach the specified value, and thus extends the lifespan of the filter. In other words, the filter media according to this embodiment is suitable for use with processing machines that have a downtime period of a certain period or longer during which the machine's operation is stopped. By utilizing the downtime of the processing machine, the amount of dust that falls due to its own weight is greater than the amount that accumulates, thereby restoring the filtration performance. With this method, a period for restoring filtration performance can be set while normal operation is being carried out, without going through any special processes or treatments, and the replacement cycle of the filter device can be extended. (filtration method)

[0048] Here, a filtration method using a filter device that utilizes the filter material according to this embodiment will be described. Processing is performed using an electrical discharge machining (EDM) machine 200 equipped with an EDM filter, and the material to be filtered contained in the processing water adheres to the surface of the EDM filter. Then, while the EDM machine 200 is stopped for a certain period of time or longer, the material to be filtered that has adhered to the EDM filter falls off by its own weight. This allows the material to be filtered that has adhered to the EDM filter to fall off by its own weight when the EDM machine 200 is not in use, such as at night, thereby suppressing a decrease in filtration performance.

[0049] The shape of the filter device is not limited to the form shown in Figure 9, but any known form can be used as appropriate. For example, the filter device 100' according to Embodiment 2 may be a form composed of multiple flat plates extending radially around the periphery, as shown in Figure 10. In this figure as well, the filter device 100' has the filter material 110' inserted into the filter cartridge 120'. [Industrial applicability]

[0050] The filter material according to the present invention, and filters for electrical discharge machining machines, filters for wire cutting machines, electrical discharge machining systems, methods for manufacturing the filter material, and filtration methods using the electrical discharge machining machine filters, can be suitably used as filter materials for filter devices for processing machines such as wire cutting machines. [Explanation of symbols]

[0051] 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 pathway 1000...Electrical discharge machining system DT... Dust

Claims

1. Supporting layer and A filter layer is laminated so that one side is fixed to the support layer, and the other side is a filter surface on which the material to be filtered accumulates. A filter material equipped with, The aforementioned filter layer contains lyocell fibers and synthetic fibers. The lyocell fiber has a fiber length distribution with only two peaks. The first peak is at 1.8 mm. The second peak is at 0.3 mm. A filter medium having a filtration surface smoothness of 0.6 seconds or more.

2. The filter material according to Claim 1, A filter material having an arithmetic mean roughness of 12 μm or less on the filter surface of the aforementioned filter layer.

3. A filter material according to either claim 1 or 2, A filter material used as a filter for processing machines that have a certain period of downtime.

4. A filter material using the filter material described in any one of Claims 1 to 3, A filter cartridge into which the aforementioned filter material is inserted A filter device equipped with, A processing tank for storing the processing fluid, The electrical discharge machining unit performs electrical discharge machining in the machining fluid stored in the aforementioned machining tank, A control unit that controls the machining operation of the electrical discharge machining unit, The processing tank and the filter device are connected by a circulation path, which is configured such that the processing fluid circulates between them. An electrical discharge machining system configured such that the processing fluid discharged from the processing tank is filtered by the filter device and recirculated back into the processing tank, The filter material is held in a position where the filtration surface is in a vertical orientation. The control unit controls the electrical discharge machining unit to stop the machining operation for a certain period of time, thereby forming an electrical discharge machining system.

5. A support layer and A filter layer is laminated so that one side is fixed to the support layer, and the other side is a filter surface on which the material to be filtered accumulates. A method for manufacturing a filter material comprising: The distribution of fiber length has only two peaks. The first peak is at 1.8 mm. The second peak is at 0.3 mm. The process involves beating each of the lyocell fibers shown and mixing them with synthetic fibers to form a filter layer, The process involves attaching the support layer to one surface of the filtration layer and laminating them together. A method for manufacturing a filter material in which the smoothness of the filtration surface, including the material, is 0.6 seconds or more.

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