Filtration Circulation System

Abstract

To provide a filtration circulation system and a drain box in which the flow of a fluid used for backwashing is not easily hindered. [Solution] A filtration circulation system that filters and circulates a polluted fluid, which is a fluid that has become contaminated with solid foreign matter due to use in a metal processing machine, includes a filtration device that filters the polluted fluid, a drain box 3 that stores fluid discharged during backwashing of the filtration device, and a backwash liquid outlet pipe L5 that is connected to the bottom surface of the drain box 3 and allows the fluid in the drain box 3 to flow out. An outlet 33a that communicates the internal space of the drain box 3 with the backwash liquid outlet pipe L5 is formed in the bottom plate 32 of the drain box 3, and the opening area of ​​the outlet 33a is smaller than the flow path cross-sectional area of ​​the backwash liquid outlet pipe L5.

Description

[Technical field]

[0001] The present invention relates to a filtration and circulation system that filters and circulates coolant liquid used in metal processing machines and the like, and to a drain box used in the filtration and circulation system. [Background technology]

[0002] Conventionally, metal processing machines use fluids such as cutting oil, grinding oil, and coolant (hereinafter collectively referred to as coolant) for the purposes of cooling, lubrication, cleaning, etc. Therefore, particulate solid foreign matter such as cutting chips and grinding chips (hereinafter referred to as sludge) is mixed into the used coolant. Generally, this coolant is repeatedly used through a circulation device, but since using coolant containing sludge affects machining such as cutting, it is necessary to remove the sludge from the coolant once it has been used.

[0003] Various filtering devices have been proposed to remove sludge from coolant. For example, the filtering device of Patent Document 1 includes a substantially cylindrical filter and an outer shell surrounding the filter, and the sludge is filtered when the coolant containing sludge passes through the filter. The filtered sludge adheres to the filter or settles at the bottom of the outer shell. If such sludge increases, it will lead to a decrease in filtering performance, so it is necessary to perform backwashing to discharge the sludge that adheres to the filter or settles at the bottom of the outer shell to the outside.

[0004] In Patent Document 1, during backwashing, the valve of the backwash liquid discharge pipe connected to the bottom of the outer shell is opened and air is allowed to flow in from the top of the filter, thereby discharging sludge from within the filtering device to the outside.

[0005] Naturally, the coolant discharged by backwashing contains sludge, and in order to reuse this coolant, the sludge must be removed. In Patent Document 1, a magnetic separator is used for this purpose (see FIG. 5 of Patent Document 1). Specifically, an auxiliary tank is provided below the filtration device, and the auxiliary tank and the magnetic separator are connected via piping. Therefore, the coolant used for backwashing falls into the auxiliary tank together with the sludge, and is reused after the sludge is removed by the magnetic separator. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] JP 2007-038205 A Summary of the Invention [Problem to be solved by the invention]

[0007] When an auxiliary tank (corresponding to the drain box in the present invention) as in the embodiment of FIG. 5 of Patent Document 1 is used, the coolant flows out to the magnetic separator after being temporarily stored in the auxiliary tank, so that the capacity of the magnetic separator can be reduced and the inflow of the coolant into the magnetic separator becomes gentle. However, in such a configuration, sludge may accumulate on the inner wall of the pipe connecting the auxiliary tank and the magnetic separator. In addition, the sludge attached to the filter during backwashing may fall in a lump state into the auxiliary tank, and the sludge may block the opening that connects the inner space of the auxiliary tank to the pipe. In either case, the outflow of the coolant from the auxiliary tank may be hindered, and the coolant may overflow from the auxiliary tank.

[0008] The present invention has been made in consideration of the above-mentioned problems, and its object is to provide a filtration circulation system and a drain box in which the flow of fluid used for backwashing is less likely to be obstructed. [Means for solving the problem]

[0009] In order to solve the above problems, the present invention provides a filtration circulation system for filtering and circulating a polluted fluid, which is a fluid that has become contaminated with solid foreign matter due to use in a metal processing machine, comprising a filtration device for filtering the polluted fluid, a drain box for storing the fluid discharged during backwashing of the filtration device, and a backwash liquid outlet pipe connected to the underside of the drain box for discharging the fluid in the drain box, wherein an outlet is formed in a bottom plate of the drain box to communicate the internal space of the drain box with the backwash liquid outlet pipe, and the opening area of ​​the outlet is smaller than the flow path cross-sectional area of ​​the backwash liquid outlet pipe.

[0010] The inventor of the present invention (hereinafter referred to as the inventor) found that when the backwash liquid in the internal space of the drain box flows out to the backwash liquid outlet pipe through the outlet, if the flow resistance of the backwash liquid outlet pipe is large, solid foreign matter is likely to accumulate in the flow path (inner wall) of the backwash liquid outlet pipe. Based on this finding, the inventor came up with a configuration in which the opening area of ​​the outlet formed in the bottom plate of the drain box is made smaller than the flow cross-sectional area of ​​the backwash liquid outlet pipe in order to reduce the flow resistance of the backwash liquid outlet pipe. This makes it possible to suppress the accumulation of solid foreign matter in the flow path of the backwash liquid outlet pipe, so that the outflow of the backwash liquid from the drain box is less likely to be hindered.

[0013] It has been found that the backwash liquid is not only hindered from flowing out from the drain box by the accumulation of solid foreign matter in the flow path of the backwash liquid outlet pipe. For example, the backwash liquid may be contaminated with solid foreign matter in the form of a lump (plate), and if such solid foreign matter gets on top of the outlet, it may hinder the backwash liquid from flowing out from the drain box. In response to this problem, the inventors have come to the discovery, through creative ingenuity, that if the outlet is shaped like a polygon (excluding regular polygons), plate-shaped solid foreign matter will be more likely to crumble.

[0014] Therefore, the present invention Filtration Circulation System In one preferred embodiment, the outlet has a polygonal shape (excluding a regular polygon) in a plan view.

[0015] In this configuration, even if a plate-shaped solid object is placed on the outlet, the force of the liquid flowing out of the outlet acts unevenly on the solid object, making it easier for the solid object to crumble and flow out together with the fluid. This makes it easier for the flow of backwash liquid from the drain box to be blocked. [Brief description of the drawings]

[0016] [Figure 1] FIG. 2 is a block diagram of the filtration circulation system. [Diagram 2] FIG. [Diagram 3] FIG. 1A is an oblique view of the drain box, FIG. 1B is a cross-sectional view of the drain box taken along line B-B', and FIG. 1C is a cross-sectional view of the drain box taken along line CC'. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0017] An embodiment of the filtration circulation system according to the present invention will be described below with reference to the drawings. Fig. 1 is a block diagram of a filtration circulation system A in this embodiment. The filtration circulation system A circulates a coolant liquid (an example of a fluid in the present invention) used for cleaning, cooling, and lubrication in a metal processing machine B, and includes a dirty tank 1, a filtration device 2, a drain box 3, and a magnetic separator 4. The piping L having a flow path for flowing the coolant liquid includes a first dirty liquid piping L1 for flowing the coolant liquid (dirty liquid, an example of a contaminated fluid in the present invention) containing sludge (an example of a solid foreign matter in the present invention) from the metal processing machine B to the dirty tank 1, a second dirty liquid piping L2 for flowing the dirty liquid from the dirty tank 1 to the filtration device 2, a clean liquid piping L3 for flowing the coolant liquid (clean liquid, an example of a clean fluid in the present invention) from which the sludge has been filtered in the filtration device 2 to the metal processing machine B, a first backwash liquid piping L4 for flowing the coolant liquid used for backwashing (hereinafter referred to as backwash liquid) from the filtration device 2 to the drain box 3, a second backwash liquid piping L5 (an example of a backwash liquid outlet pipe in the present invention) for flowing the backwash liquid from the drain box 3 to the magnetic separator 4, and a return piping L6 for flowing the coolant liquid from which the sludge has been removed in the magnetic separator 4 to the dirty tank 1. Furthermore, as valves V for controlling the opening and closing of the flow paths of the pipes L, a valve V1 for cleaning liquid piping that controls the opening and closing of the flow path of the cleaning liquid pipe L3 and a valve V2 for backwash liquid piping that controls the opening and closing of the flow path of the first backwash liquid pipe L4 are provided. Note that in Fig. 1, the pipes L and part of the valves V, as well as a pump for circulating the coolant liquid, etc. are omitted.

[0018] Next, the flow of the coolant in the filtration circulation system A will be briefly described. First, the flow during normal circulation and filtration will be described. At this time, the valve V1 for the clean liquid pipe is "open" and the valve V2 for the backwash liquid pipe is "closed". The coolant (dirty liquid) used in the metal processing machine B and containing sludge flows into the dirty tank 1 through the first dirty liquid pipe L1. The dirty liquid in the dirty tank 1 is supplied to the filtration device 2 through the second dirty liquid pipe L2 by a pump (not shown). As will be described in detail later, a filter is provided inside the filtration device 2, and the sludge is filtered out of the dirty liquid by the filter. The coolant (clean liquid) from which the sludge has been removed is supplied again to the metal processing machine B through the clean liquid pipe L3 and used.

[0019] If this process continues, sludge will adhere to the filter of the filtration device 2 or settle at the bottom of the filtration device 2. This will lead to a decrease in the filtration performance of the filtration device 2, so it is necessary to periodically perform backwashing to remove this sludge. During backwashing, the valve V1 for the clean liquid piping is "closed" and the valve V2 for the backwash liquid piping is "open." However, as shown in Figure 3, if multiple filtration devices 2 are provided and the timing of each backwash is staggered so that any one of the filtration devices 2 can always perform filtration, the valve V1 for the clean liquid piping remains "open."

[0020] Although the details will be described later, the first backwash liquid pipe L4 is connected to the lower end of the filtration device 2 and extends straight down. In addition, the flow path of the first backwash liquid pipe L4 has a relatively large diameter. Therefore, when the backwash liquid pipe valve V2 is controlled to be "open", the coolant liquid in the filtration device 2 flows out with force. At this time, sludge adhering to the filter of the filtration device 2 or settling at the bottom of the filtration device 2 flows out together with the backwash liquid through the first backwash liquid pipe L4 to the drain box 3.

[0021] The backwash liquid flows into the drain box 3, passes through the second backwash liquid pipe L5, and flows out to the magnetic separator 4. In the magnetic separator 4, the magnetic sludge in the backwash liquid is removed. The backwash liquid from which the magnetic sludge has been removed is returned to the dirty tank 1 through the return pipe L6.

[0022] 2 is a cross-sectional view of the filtration device 2 in this embodiment. The filtration device 2 is provided with a casing consisting of an upper casing 21 that is substantially cylindrical, has a ceiling, and opens downward, and a substantially funnel-shaped lower casing 22 that opens upward. Spaces are formed inside the upper casing 21 and the lower casing 22, and are referred to as the upper space 21a and the lower space 22a, respectively. The lower end of the upper casing 21 and the upper end of the lower casing 22 are fastened watertightly using screws or the like, whereby the upper casing 21 and the lower casing 22 are connected and fixed to form a casing. At this time, the openings of the upper casing 21 and the lower casing 22 are fixed so as to coincide with each other, and the lower space 22a and the upper space 21a are communicated with each other.

[0023] The lower casing 22 is formed with an inlet through which the dirty liquid flows in, and a second dirty liquid pipe L2 is connected to the inlet. Meanwhile, the upper casing 21 is formed with an outlet through which the clean liquid flows out, and a clean liquid pipe L3 is connected to the outlet. In addition, a discharge port that opens downward is formed at the bottom end of the lower casing 22, and a first backwash liquid pipe L4 is connected to the discharge port.

[0024] The upper casing 21 is provided with a filter section for filtering sludge from the dirty liquid. The filter section includes a support 23 and a filter body (not shown) that is contained in the support 23. The support 23 is a generally cylindrical body, with the upper part closed by a top plate and the lower part open to form an inlet. A plurality of leakage holes are formed in the wall surface of the support 23. The diameter of the leakage holes is larger than the particle size of the sludge, but there is no particular limit. It is not preferable that the diameter of the leakage holes is too small, since it will hinder the outflow of the coolant liquid.

[0025] The support 23 is disposed so that an inlet coincides with the opening of the upper casing 21 and the opening of the lower casing 22. Therefore, the contaminated liquid flows from the lower space 22a to the upper space 21a, more specifically, into the internal space 23a of the support 23, through the inlet. In addition, as shown in Fig. 2, a gap is formed between the outer peripheral surface of the support 23 and the inner peripheral surface of the upper casing 21, which serves as a flow path for the filtered coolant liquid (clean liquid).

[0026] The filter body is for filtering the coolant liquid containing sludge and removing the sludge from the coolant liquid, and is a filter cloth or the like having finer mesh than the particle size of the object to be filtered. As the filter body, a single-layer or multi-layered synthetic fiber nonwoven fabric or plastic fiber fabric or the like can be used.

[0027] As such a filtration device 2, for example, the filtration device disclosed in JP 2023-025359 A can be used.

[0028] Next, the process of filtering the contaminated liquid by the filtering device 2 will be described with reference to Figure 2. Note that the arrows in the figure indicate the flow of the coolant liquid.

[0029] The coolant liquid (dirty liquid) used in the metal processing machine B and containing sludge flows from the second dirty liquid pipe L2 into the lower space 22a of the lower casing 22. At this time, the backwash liquid pipe valve V2 is closed, and the dirty liquid does not flow out from the first backwash liquid pipe L4. Therefore, if the dirty liquid continues to flow in, the level of the dirty liquid in the lower space 22a rises. Then, when the water level exceeds the upper end of the lower space 22a, the dirty liquid flows into the upper space 21a, that is, the internal space 23a of the support 23, through the inlet. The dirty liquid that has flowed into the internal space 23a of the support 23 is subjected to pressure from below due to the inflow of further dirty liquid, and when the internal space 23a of the support 23 is filled with dirty liquid, this pressure acts as a force that causes the dirty liquid in the internal space 23a of the support 23 to flow out of the support 23. At this time, because the top of the support 23 is closed, the dirty liquid in the internal space 23a of the support 23 can only flow out radially outward from the support 23. At this time, sludge with a relatively high specific gravity settles, but sludge with a low specific gravity floats inside. Pressure in the radial outward direction acts on such sludge. As mentioned above, the mesh of the filter body is finer than the grain size of the sludge, so this pressure in the radial outward direction causes the sludge to adhere to the inner surface of the filter body, and only the coolant liquid flows outward from the filter body.

[0030] In this way, the coolant liquid (clean liquid) filtered by the filter body flows out of the support body 23 through the leakage hole of the support body 23. The coolant liquid that has flowed out of the support body 23 flows through a flow path formed between the support body 23 and the upper casing 21 to the clean liquid pipe L3. The clean liquid is then reused in the metal processing machine B.

[0031] In such a filtering device 2, as described above, sludge adheres to the inner surface of the filter body or settles at the bottom of the lower casing 22. If such sludge increases inside the filtering device 2, the filtering performance decreases, so it is necessary to periodically remove the sludge, that is, perform so-called backwashing. When performing backwashing, the backwash liquid piping valve V2 is opened. Then, together with the coolant liquid that has accumulated inside the filtering device 2, the sludge that has settled at the bottom or adhered to the inner surface of the filter body is discharged through the first backwash liquid piping L4. Hereinafter, the coolant liquid discharged through the first backwash liquid piping L4 is referred to as the backwash liquid.

[0032] As described above, in the filtration circulation system A of the present invention, the drain box 3 is provided below the first backwash liquid pipe L4, so that the backwash liquid flows into the drain box 3. The backwash liquid that flows into the drain box 3 flows into the magnetic separator 4 through the second backwash liquid pipe L5. Then, the coolant liquid from which the magnetic sludge has been removed by the magnetic separator 4 flows back to the dirty tank 2 through the return pipe L6.

[0033] By providing the drain box 3 between the filtration device 2 and the magnetic separator 4, the capacity of the magnetic separator 4 can be reduced. In addition, if the backwash liquid that flows out vigorously from the first backwash liquid pipe L4 is allowed to flow directly into the magnetic separator 4, undesirable phenomena such as foaming may occur. However, by passing the backwash liquid through the drain box 3, the occurrence of such undesirable phenomena can be suppressed.

[0034] However, it has been found that sludge contained in the backwash liquid is likely to accumulate on the inner wall of the second backwash liquid pipe L5 due to piping resistance. In the drain box 3 according to the present invention, the piping resistance of the second backwash liquid pipe L5 is reduced by the following configuration, thereby suppressing the accumulation of sludge.

[0035] FIG. 3(a) is a perspective view of the drain box 3 in this embodiment, FIG. 3(b) is a B-B' cross-sectional view, and FIG. 3(c) is a C-C' cross-sectional view. Note that FIG. 3(c) does not show the top plate 31. The drain box 3 is a hollow, approximately rectangular parallelepiped shape, and is installed with a slight inclination so that the left side in FIG. 3(a) (the side where the outlet 33a is formed) is slightly downward. The top plate 31 is connected to the first backwash liquid pipe L4. Note that in this embodiment, since two filtration devices 2 are provided, two first backwash liquid pipes L4 are connected to the drain box 3. In this way, by providing a plurality of filtration devices 2 and shifting the timing of backwashing each filtration device 2, backwashing can be performed without stopping the circulation filtration process in the entire filtration circulation system A.

[0036] As shown in Fig. 3(c), an opening 32a is formed in the bottom plate 32 of the drain box 3, and the second backwash liquid pipe L5 communicates with the internal space of the drain box 3 through the opening 32a. In this embodiment, the shape of the opening 32a and the cross-sectional shape of the flow path of the second backwash liquid pipe L5 are congruent and their areas are the same, but the cross-sectional area of ​​the flow path of the second backwash liquid pipe L5 may be larger than the opening area of ​​the opening 32a. The cross-sectional area of ​​the flow path is the cross-sectional area in a plane perpendicular to the flow direction of the flow path.

[0037] In this embodiment, an elastic plate 33 having an outlet 33a formed thereon is provided above the opening 32a. The elastic plate 33 is slightly larger than the opening 32a and is arranged to cover the entire opening 32a, and its periphery is pressed and fixed by a pressing plate 34. The opening area of ​​the outlet 33a is smaller than the flow path cross-sectional area of ​​the second backwash liquid pipe L5, and the entire outlet 33a is arranged to fit inside the inner circumference of the second backwash liquid pipe L5. This reduces the piping resistance of the second backwash liquid pipe L5 and suppresses the accumulation of sludge. In this embodiment, the outlet 33a is a pentagon having two right-angled corners, so-called a home base shape.

[0038] The backwash liquid flowing out from the filtration device 2 may contain not only sludge that has settled at the bottom of the filtration device 2, but also sludge that has adhered to the filter body. In particular, in the case of a filtration device 2 having a support as disclosed in Figs. 6 and 7 of JP 2023-025359 A, sludge adheres to the filter body in a plate-like form, and this plate-like sludge may flow into the drain box 3 by backwashing. Such plate-like sludge may clog the outlet 33a and hinder the outflow of the backwash liquid from the second backwash liquid piping L5.

[0039] The inventors of the present invention, after much ingenuity, have found that if the shape of the outlet 33a is a polygon (excluding regular polygons), the plate-like sludge on the outlet 33a is likely to collapse. This is because, when the shape of the outlet 33a is a polygon (excluding regular polygons), the force of the backwash liquid trying to flow out of the outlet 33a acts unevenly on the plate-like sludge, making the plate-like sludge more likely to collapse. The inventors have also found that, among polygons, pentagons and hexagons are more preferable.

[0040] In this manner, in the circulation filtration system A and the drain box 3 according to the present invention, the opening area of ​​the outlet 33a formed in the bottom plate 33 of the drain box 3 is made smaller than the flow cross-sectional area of ​​the second backwash liquid pipe L5, thereby reducing the flow resistance of the flow path of the second backwash liquid pipe L5. This makes it possible to suppress the accumulation of sludge in the flow path of the second backwash liquid pipe L5. In addition, by making the shape of the outlet 33a polygonal (excluding a regular polygon), plate-like or other clumpy sludge that sits above the outlet 33a is made to easily collapse, thereby preventing the sludge from clogging the outlet 33a.

[0041] [Another embodiment] (1) In the above embodiment, the drain box 3 is provided with the elastic plate 33 having the outlet 33a, but the elastic plate 33 may be omitted. In this case, the opening 32a serves as the outlet, and the opening 32a may be formed so that its opening area is smaller than the flow path cross-sectional area of ​​the second backwash liquid piping L5.

[0042] (2) In the above embodiment, the opening shape of the outlet 33a and the cross-sectional shape of the second backwash liquid pipe L5 are neither congruent nor similar, but they may be similar. Even in this case, the opening area of ​​the outlet may be smaller than the cross-sectional area of ​​the second backwash liquid pipe L5. For example, both may be circular, and the diameter of the opening shape of the outlet 33a may be smaller than the diameter of the cross-sectional shape of the second backwash liquid pipe L5. [Industrial Applicability]

[0043] The present invention can be used in filtration and circulation systems that filter and circulate fluids containing solid foreign matter, such as coolant liquids used in metal processing machines, and in drain boxes used in such filtration and circulation systems. [Explanation of symbols]

[0044] A: Filtration circulation system B: Metal processing machinery L5: Backwash liquid second pipe (backwash liquid outflow pipe) 1: Dirty Tank 2:Filtration device 3: Drain box 33a: Outlet 4: Magnetic separator

Claims

1. A filtration and circulation system for filtering and circulating a contaminated fluid, which is a fluid that has become contaminated with solid foreign matter due to use in a metal processing machine, comprising: A filtration device for filtering the contaminated fluid; a drain box for accommodating the fluid discharged during backwashing of the filtration device; A backwash liquid outlet pipe connected to a lower surface of the drain box and allowing the fluid in the drain box to flow out, An outlet is formed in a bottom plate of the drain box to communicate an internal space of the drain box with the backwash liquid outlet pipe, A filtration circulation system in which the opening area of ​​the outlet is smaller than the flow path cross-sectional area of ​​the backwash liquid outlet pipe.

2. The filtration circulation system according to claim 1 , wherein the outlet has a polygonal shape (excluding a regular polygon) in a plan view.

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