Coolant tank and machine tool

Abstract

The present invention comprises: a storage tank TN2 in which a coolant, which has passed through a processing region in which a workpiece is processed, is stored; a liquid circulation pipe 1 provided with a suction port 11 for suctioning a liquid to be processed containing floating oil, a solid component, and a coolant from the liquid surface or the vicinity of the liquid surface of the coolant in the storage tank TN2, and a discharge port 12 through which the liquid to be treated is discharged; a filter 41 in which the solid component is filtered from the liquid to be processed discharged from the discharge port 12 of the liquid circulation pipe 1; and a separation tank 5 in which the liquid to be processed, which has passed through the filter 41, is separated into the floating oil and the coolant. The discharge port 12 of the liquid circulation pipe 1 is opened to the atmosphere, and the filter 41 is provided so as to be separated from the discharge port to the outside.

Description

Coolant tanks and machine tools

[0001] The present invention relates to a coolant tank for use in a machine tool.

[0002] For example, when machining metals, coolant is used to cool the workpiece during cutting, to improve lubrication between the tool and the workpiece to improve cutting performance, and to remove chips from the machining area for automation. In machine tools, coolant is supplied to the machining area and other areas by a device called a coolant tank, and the coolant used in the machining area is returned to the coolant tank. The coolant tank separates components such as chips and machine oil used in the sliding parts of the machine tool from the used coolant, turning it into clean coolant that can be reused and supplied to the machining area.

[0003] When used coolant is stored in a storage tank, some components, such as machine oil, with a light specific gravity, rise to the surface of the liquid. Such oil components are called floating oil, and a float-type recovery mechanism, such as that shown in Patent Document 1, is used to recover them. This system includes a float that floats on the surface of the stored used coolant and piping with a suction port that opens at or near the liquid surface, and uses a pump to recover the floating oil that has risen to the surface of the coolant.

[0004] Incidentally, not only floating oil but also floating sludge consisting of fine metal particles and the like is present on the surface of the coolant. As a result, the liquid to be treated, including floating oil, floating sludge, and coolant, is sucked from the suction port. These components must be separated individually and reused or disposed of. For this reason, a mechanism such as a Y-shaped strainer is installed in the liquid distribution pipe through which the liquid to be treated flows, and the floating sludge is first separated from the liquid to be treated.

[0005] Using a strainer to capture floating sludge in a liquid flow pipe like this can cause clogging, necessitating maintenance such as removing the strainer from the pipe and disposing of the trapped floating sludge. However, because the condition inside the pipe cannot be seen, it is difficult for operators to know when maintenance is required. For example, depending on the type of machining, the amount of floating sludge generated may suddenly increase. In that case, even if regular maintenance is performed, it may become difficult to collect floating oil and other substances before that time, which could result in a decline in the quality of the coolant supplied to the machining area. However, excessively frequent maintenance can also be an obstacle to automating machining using machine tools.

[0006] Japanese Patent Publication No. 2023-120506

[0007] The present invention has been made in consideration of the above-mentioned problems, and aims to provide a coolant tank that makes it easy for an operator to grasp the amount of floating oil, solid components, and solid components separated from a liquid to be treated that contains coolant, and enables disposal of the separated solid components, etc. at an appropriate time, and a machine tool that uses the same.

[0008] That is, the coolant tank of the present invention comprises a storage tank in which coolant that has passed through a processing area where workpiece processing is performed is stored, a liquid circulation pipe having a suction port for sucking the liquid to be treated, which contains floating oil, solid components, and coolant, from the liquid surface of the coolant or near the liquid surface in the storage tank, and a discharge port from which the liquid to be treated is discharged, a filter for filtering solid components from the liquid to be treated discharged from the discharge port of the liquid circulation pipe, and a separation tank in which the liquid to be treated that has passed through the filter is separated into floating oil and coolant, and is characterized in that the discharge port of the liquid circulation pipe is open to the atmosphere, and the filter is provided outside and spaced apart from the discharge port.

[0009] In this case, the filter can be installed outside the piping, and the amount of solid components on the filter that have separated from the liquid to be treated can be easily determined, allowing the operator to accurately determine whether or not maintenance of the filter is necessary and to carry out maintenance at the appropriate time.

[0010] In order to prevent the liquid to be treated that is discharged from the discharge port from scattering around and to make it easy to visually check the clogging state of the filter, the filter should be provided on the lower side and a collection container should be provided on the upper side which has an opening into which the liquid to be treated that is discharged from the discharge port of the liquid flow pipe flows.

[0011] In order to prevent the liquid to be treated from causing splashes on the liquid surface of the separation tank, to make it easier to maintain the separation state of the floating oil and coolant, and to prevent splashes from flowing into an unexpected discharge section and reducing separation accuracy, the recovery container is detachably attached to the separation tank, and a cylindrical wall is formed on the outlet side of the filter to guide the liquid to be treated that passes through the filter toward the separation tank.

[0012] When separating the liquid to be treated into floating oil and coolant after solid components have been separated, for example, the difference in their specific gravities is used to separate them. That is, a coolant outlet is formed below the boundary between the floating oil and coolant at the reference water level, and a floating oil outlet is formed above the boundary, and the two are discharged separately. Recently, the use of coolant has expanded beyond simply cooling workpieces and tools during machining to various purposes, such as removing chips, and the amount used per unit time has increased. Accordingly, the amount of liquid to be treated that is returned to the coolant tank and sucked in to separate the floating oil and solid components has also increased. This leads to greater fluctuations in the flow rate of the liquid to be treated. Therefore, if the height gap between the coolant outlet and the floating oil outlet is kept at the same level as before, coolant may also leak from the floating oil outlet. However, if the gap is too large, it will take longer for the floating oil to be separated and discharged to the outside, resulting in a longer period during which the floating oil recovery mechanism in the coolant tank appears not to be operating. In this case, even if the function of separating the floating oil and coolant is actually working properly, it may lead to suspicion that some kind of malfunction has occurred, and users may lose confidence in the coolant tank.

[0013] To solve this problem, another aspect of the coolant tank of the present invention is configured to shorten the time it takes for components to be separated and discharged from a separation tank even when the flow rate or fluctuation of the liquid to be treated is large. That is, the separation tank may include a storage section for storing the liquid to be treated that has passed through the filter, a first discharge section through which the coolant separated in the storage section flows to the outside, and a second discharge section through which the floating oil separated in the storage section flows to the outside. The first discharge section is formed to extend horizontally relative to a main partition wall forming the storage section and includes a first inlet opening through which the coolant flows in, a buffer section in which the coolant flowing in from the inlet opening accumulates, and a first discharge outlet formed on an outer partition wall forming the buffer section outside the main partition wall and through which the coolant is discharged to the outside. With this structure, even if the first discharge outlet is fixed in shape and size determined by the standards of a socket or the like for connecting piping, the height and flow rate at which the coolant is discharged to the outside can be determined by the first inlet opening. Therefore, even if the flow rate of the liquid to be treated or its fluctuations are large, it is easy to reduce the gap between the height at which the floating oil is discharged and the height at which the coolant is discharged in the separation tank.

[0014] In order to prevent the coolant level from rising suddenly even when the flow rate of the liquid to be treated is large and to make it easier to reduce the gap between the floating oil and the height at which the coolant is discharged, the flow path cross-sectional area of ​​the first inlet opening should be larger than the flow path cross-sectional area of ​​the first outlet opening.

[0015] In order to easily construct a piping configuration for reusing the separated coolant in the machining area, the first outlet may be formed by a socket to which a piping is connected.

[0016] A specific example of how floating oil is discharged from the separation tank is one in which the second discharge section is formed to extend horizontally relative to the main body partition that forms the storage section, and is equipped with a second inlet opening through which floating oil flows, and the height of the lower end of the second inlet opening is set higher than the height of the lower end of the first inlet opening.

[0017] In order to prevent a decrease in the accuracy of separation of the floating oil and the coolant by making it difficult for droplets of the liquid to be treated discharged from the discharge port of the liquid flow pipe and droplets generated on the liquid surface in the separation tank to flow into the second discharge section, the separation tank may further include a support section for supporting the recovery container, and when the recovery container is supported by the support section, the filter may be configured to be positioned closer to the first discharge section than the second discharge section.

[0018] In order to prevent the liquid to be treated from continuing to flow out of the discharge port of the liquid circulation pipe due to the hydraulic head in the tank even in the event of an emergency stop of the pump, it is sufficient to further include a pump provided in the liquid circulation pipe and an air vent pipe connecting the discharge side of the pump in the liquid circulation pipe to the upper air layer in the storage tank. In this case, air will naturally flow into the discharge side when the pump stops, preventing the liquid to be treated from flowing out by a siphon.

[0019] In order to temporarily stop the liquid to be treated from flowing out of the outlet during maintenance of the filter, etc., the liquid circulation pipe may further include an opening / closing valve provided between the pump and the outlet.

[0020] In a machine tool equipped with the coolant tank of the present invention and a splash guard with the machining area formed inside, the operator can easily see the degree of clogging of the filter, etc., and therefore perform maintenance at the appropriate time, making it easier to realize highly automated machining processes.

[0021] In this way, with the coolant tank according to the present invention, the outlet of the liquid flow pipe is open to the atmosphere, and the filter is provided at a distance from the outlet, so that the filter can be exposed to the atmosphere and the clogging state of the filter can be checked as needed. Therefore, even if there are fluctuations in the processing process, maintenance of the filter can be performed at an appropriate time, and high separation accuracy of floating oil and floating sludge can be maintained.

[0022] 1 is a schematic perspective view showing the appearance of a machine tool according to an embodiment of the present invention; 2 is a schematic configuration diagram of a machine tool and a coolant tank according to the embodiment; 3 is a schematic diagram of a floating oil separation mechanism according to the embodiment; 4 is a schematic perspective view of the floating oil separation mechanism according to the embodiment; 5 is a schematic perspective view of the floating oil separation mechanism according to the embodiment with a collection container removed;

[0023] Hereinafter, a coolant tank 100 according to one embodiment of the present invention and a machine tool 200 using the same will be described with reference to the drawings.

[0024] FIG. 1 shows the external appearance of machine tool 200. In this specification, the term "machine tool" is a concept that encompasses various devices that have the function of machining a workpiece. In this specification, a horizontal machining center is used as an example of machine tool 200, but machine tool 200 is not limited to this. For example, machine tool 200 may be a vertical machining center. Machine tool 200 may also be a turning center, a five-axis machining center, or a multi-tasking machine. In addition, machine tool 200 may be a grinding machine or other cutting machine. Furthermore, machining is a concept that does not only include subtractive machining, but may also include additive machining.

[0025] 1, machine tool 200 is equipped with a cover body that separates the inside and outside of the machine, and an operation panel. This machine tool 200 has a processing area where cutting work is performed inside the machine, which is separated by an inner door, and a waiting area where the next workpiece is placed on a pallet while waiting.

[0026] The cover body is also called a splash guard, and forms the exterior of the machine tool 200 and separates the inside and outside of the machine.

[0027] The operation panel is configured by, for example, a general-purpose computer, and includes an upper housing and a lower housing that are rotatably connected to each other by a hinge mechanism at the center.

[0028] Next, the configuration of the coolant circuit formed by the coolant tank 100 used in the machine tool 200 of this embodiment will be described with reference to FIG. 2. Note that in FIG. 2, the layout of the devices may differ from the actual layout in order to make the functional connections easier to understand. Therefore, FIG. 2 may not accurately represent the structure, size, position, etc. of each device. Also, although descriptions of mechanisms typically used in machine tools, such as the table, ATC, CNC, etc., in the machine tool 200 are omitted, existing mechanisms may be used, for example.

[0029] As shown in Figure 2, this coolant circuit circulates coolant between the inside and outside of machine tool 200, and is configured to collect coolant used inside the machine that has become contaminated with chips, lubricating oil, etc. (hereinafter also referred to as dirty coolant), convert it into coolant from which the chips and lubricating oil have been removed (hereinafter also referred to as clean coolant), and supply it back into the machine.

[0030] This coolant circuit includes a discharge mechanism 2 that discharges coolant within the machine, a chip conveyor 3 that removes chips and other contaminants from the dirty coolant used and collected within the machine and discards them externally, a flat recovery tank TN1 that stores the coolant from which chips have been removed by the chip conveyor 3, a vertical storage tank TN2 that stores the dirty coolant from which chips have been removed, and a pump unit PP that pressure-feeds clean coolant purified by the storage tank TN2 or various separation mechanisms (not shown) installed downstream of the storage tank TN2 to each discharge mechanism 2. The coolant is configured to circulate within this coolant circuit. Furthermore, the coolant tank 100 of this embodiment further includes an oil separation mechanism OS that collects and separates floating oil, such as lubricating oil or machine oil, that floats on the surface of the dirty coolant stored in the storage tank TN2.

[0031] Each component will be described in detail. The discharge mechanisms 2 installed inside the machine tool 200 are configured in various ways to accommodate various purposes. Some examples include a discharge mechanism 2 installed in the ceiling to supply shower coolant, a discharge mechanism 2 installed in the lower part of the machine tool 200 to direct chips in a chip container to the chip conveyor 3, and a discharge mechanism 2 installed in the tip of the tool TL to lubricate and cool during machining. There are various uses not described here, and the discharge mechanisms 2 are installed in positions appropriate for each. The discharge mechanism 2 is configured, for example, as a nozzle, and coolant pressurized by the pump device PP is sprayed into the machine. In the following explanation, the through-spindle coolant mechanism ST will be particularly described as an example of the discharge mechanism 2. The through-spindle coolant mechanism ST has a through-path provided in the tool TL and the spindle S, allowing coolant to be discharged directly from the tip of the tool TL to the machining point, etc. In the first embodiment, for example, an operator can adjust the pressure at which the coolant is discharged from the tip of the tool TL depending on the machining process and machining conditions.

[0032] The chip conveyor 3 is housed in a housing and scrapes out chips contained in the coolant, discharging them into a chip bucket or the like located outside the machine. A cylindrical metal drum filter 31 is also provided inside the chip conveyor 3 to filter out minute metal fragments. Coolant that passes through the drum filter 31 flows into a collection tank TN1.

[0033] The recovery tanks TN1 are arranged in a row in the width direction (toward the back of the page) of the chip conveyor 3 below the machine tool 200, but for ease of understanding, they are shown in Figure 2 as being arranged in a row in the length direction of the chip conveyor 3. The coolant recovered in the recovery tank TN1 is pumped up to the upper side of the subsequent storage tank TN2 by a transfer pump.

[0034] The storage tank TN2 functions as a buffer for the coolant, and the clean coolant that passes through this storage tank TN2 is pressure-fed by the pump device PP to each discharge mechanism 2. For ease of understanding, Fig. 2 only shows the flow path L between the through-spindle mechanism ST and the pump device PP, but the other discharge mechanisms 2 are connected to the storage tank TN2. A pressure sensor PS and a flow rate sensor FM are provided on the flow path L as fluid sensors for measuring the pressure or flow rate of the coolant being discharged as the through-spindle coolant.

[0035] The rotation speed of the pump device PP is controlled by changing the frequency of the current input from the inverter 5. In this embodiment, the frequency output by the inverter (not shown) is controlled by pressure feedback control so as to reduce the deviation between the pressure measured by the pressure sensor PS and the set pressure, which is a set value.

[0036] Next, the oil separation mechanism OS will be described in detail with reference to Figures 2 to 5. The oil separation mechanism OS sucks floating oil and floating sludge, such as fine metal powder, that rise to the surface of the dirty coolant in the storage tank TN2, and is responsible for part of the separation operation required to produce clean coolant. This oil separation mechanism OS sucks the floating oil, floating sludge, and the liquid to be treated, which contains coolant, from the liquid surface of the coolant stored in the storage tank TN2 or near the liquid surface. The oil separation mechanism OS then first separates the floating sludge, which is a solid component, from the sucked liquid to be treated, and then separates the floating oil and coolant from the liquid to be treated from which the floating sludge has been separated. More specifically, the oil separation mechanism OS is equipped with a suction port 11 that sucks the liquid to be treated from the liquid surface of the coolant in the storage tank TN2 or near it, and a discharge port 12 from which the sucked liquid to be treated is discharged, and is also equipped with a liquid circulation pipe 1 through which the liquid to be treated flows, a recovery container 4 that is provided a predetermined distance away from the discharge port 12 of the liquid circulation pipe 1 and has a filter 41 that separates solid components such as floating sludge from the liquid to be treated, and a separation tank 5 in which the liquid to be treated that has passed through the filter 41 of the recovery container 4 is stored and the floating oil and coolant are separated due to the difference in their specific gravities.

[0037] The liquid flow pipe 1 is flexible at least on the storage tank TN2 side, allowing the position of the suction port 11 to be changed depending on the level of the coolant in the storage tank TN2. A float 1F is provided near the suction port 11 of the liquid flow pipe 1, so that the suction port 11 is maintained near the liquid level of the coolant in the storage tank TN2. The discharge port 12 faces vertically downward and is open to the atmosphere, so that the liquid to be treated discharged from the discharge port 12 travels a predetermined distance through the air before entering the filter 41. A pump 13 is provided midway along the liquid flow pipe 1 to generate suction force for sucking the liquid to be treated through the suction port 11. This pump 13 is, for example, a diaphragm pump, and a predetermined amount of air is mixed into the sucked liquid to be treated.

[0038] Furthermore, a vent pipe AL is provided, the distal end of which is connected between the discharge side of the pump 13 and the discharge port 12 of the liquid distribution pipe 1, and the proximal end of which is connected to a portion of the storage tank TN2 where an upper air layer exists at a height that the coolant cannot reach. In the event of an emergency stop of the pump 13, for example, air flows into the discharge side of the pump 13 via the vent pipe AL, and thereafter air flows between the discharge port 12 of the liquid distribution pipe 1, and a siphon prevents the coolant in the storage tank TN2 from flowing out from the discharge port 12 below. In addition, a manually operable open / close valve V is provided in the liquid distribution pipe 1 between the pump 13 and the discharge port 12.

[0039] The configuration downstream of the discharge port 12 of the liquid flow pipe 1 will be described in further detail with reference to Figures 3 to 5. The liquid to be treated discharged from the discharge port 12 travels through the air and flows into the collection container 4 through an inlet opening at the top. The collection container 4 is roughly box-shaped with an open top 42, and a filter 41 made of metal mesh is provided on its bottom side. A cylindrical wall 43 extends around the lower periphery of the filter 41 toward the separation tank 5. Solid components such as floating sludge in the liquid to be treated that flow into the filter 41 are filtered by the filter 41, while liquid components such as floating oil and coolant flow down the cylindrical wall 43 into the separation tank 5. The tip of the cylindrical wall 43 is configured to be immersed near the liquid surface of the liquid to be treated when a specified amount of the liquid to be treated is stored in the separation tank 5, allowing separation of the floating oil and coolant. Furthermore, with the maintenance hatch of the coolant tank 100 open, the operator can visually check the flow of the liquid to be treated flowing out of the outlet 12 into the air, and can also visually check the condition of the filter 41 exposed to the air through the opening in the top 42 of the recovery container 4. For example, by closing the valve V and temporarily stopping the flow of the liquid to be treated, the filter 41 can be placed in a state where it is not exposed to the suspended liquid, making it easy to evaluate the clogging state of the filter 41. Therefore, before the filter 41 reaches a state where it cannot fully function, the recovery container 4 can be removed from the separation tank 5, and appropriate maintenance can be performed, such as removing and disposing of the solid components on the filter 41.

[0040] The separation tank 5 includes a storage section 5T in which the liquid to be treated that has passed through the filter 41 and from which solid components such as floating sludge have been removed is stored, a first discharge section 51 in which the coolant that separates to the bottom in the storage section 5T due to differences in specific gravity is discharged to the outside of the separation tank 5, a second discharge section 52 in which the floating oil that separates to the top in the storage section 5T due to differences in specific gravity is discharged to the outside of the separation tank 5, and a support section 53 that supports the recovery container 4. The first discharge section 51 and the second discharge section 52 are provided separately on the left and right sides of the storage section 5T, respectively.

[0041] The first discharge section 51 includes a first inlet opening 511 formed in the main body partition 5W that forms the storage section 5T and having a rectangular shape extending horizontally; a buffer section 513 in which the coolant flowing in through the first inlet opening 511 accumulates; and a first discharge port 512 formed in the outer partition BW that forms the buffer section 513. The first discharge port 512 is provided on the outside and its shape is determined by a socket for connecting a pipe for returning the coolant to the interior of the machine. In this embodiment, the opening shape is approximately circular, and its flow path area is small when the coolant level is low. The flow path cross-sectional area of ​​the first inlet opening 511 is configured to be larger than the flow path cross-sectional area of ​​the first discharge port 512. Therefore, even if the flow rate of the coolant inflow increases, the coolant level does not increase abruptly, as compared to when the coolant flows directly into the opening formed by the socket, and can increase or decrease proportionally.

[0042] The second discharge section 52 includes a second inlet opening 521, which is a slit formed in the main body partition wall 5W that forms the reservoir 5T. The horizontal length of the second inlet opening 521 is shorter than that of the first inlet opening 511. Furthermore, the lower end of the second inlet opening 521, which determines the discharge level of the floating oil, is set higher than the lower end of the first inlet opening 511, which determines the discharge level of the coolant. In this embodiment, the first inlet opening 511 is rectangular, with a larger cross-sectional flow path area than the socket. This prevents the level of the liquid to be treated in the reservoir 5T from suddenly increasing or decreasing, even when the flow rate or its fluctuations are large. This allows for a small gap between the coolant discharge level and the floating oil discharge level, thereby shortening the time required for the floating oil to be discharged from the second discharge section 52 to the oil pan 6 compared to conventional systems. This reduces the likelihood of misunderstandings that the time it takes for the floating oil to be discharged to the oil pan 6 to be long and that a malfunction or other problem has occurred.

[0043] Other embodiments will now be described. The vertical storage tank may be omitted, and the coolant may be pumped from a recovery tank to each discharge mechanism. The oil separation mechanism according to the present invention may be configured to recover floating oil from a flat recovery tank. Pumps based on various known operating principles may also be used. The filter may be something other than a metal mesh. It may be a punched plate or a nonwoven mesh. In other words, anything that can filter out solid components may be used. The liquid to be treated discharged from the discharge port does not have to flow directly into the filter. For example, it may hit the wall of the recovery container and then flow down the wall into the filter.

[0044] In addition, various modifications and combinations of parts of each embodiment may be made as long as they do not go against the spirit of the present invention.

[0045] 200 Machine tool, 100 Coolant tank, 1 Liquid circulation pipe, 11 Suction port, 12 Discharge port, 41 Filter, 5 Separation tank, 51 First discharge section, 52 Second discharge section, 5T Storage section

Claims

1. A coolant tank comprising: a storage tank for storing coolant which has passed through a machining area where workpieces are machined; a liquid circulation pipe having a suction port for sucking in the liquid to be treated, which contains floating oil, solid components and coolant, from the liquid level of the coolant or near the liquid level in the storage tank, and a discharge port from which the liquid to be treated is discharged; a filter for filtering solid components from the liquid to be treated discharged from the discharge port of the liquid circulation pipe; and a separation tank in which the liquid to be treated which has passed through the filter is separated into floating oil and coolant, wherein the discharge port of the liquid circulation pipe is open to the atmosphere, and the filter is provided at a distance from the discharge port to the outside.

2. A coolant tank as claimed in claim 1, further comprising a recovery container on an upper side thereof having an opening into which the liquid to be treated discharged from the discharge port of the liquid circulation pipe flows.

3. A coolant tank as described in claim 2, wherein the recovery container is detachably attached to the separation tank, and a cylindrical wall is formed on the outlet side of the filter to guide the liquid to be treated that passes through the filter toward the separation tank.

4. A coolant tank as described in claim 2, wherein the separation tank comprises: a storage section in which the liquid to be treated that has passed through the filter is stored; a first discharge section through which the coolant separated in the storage section flows out to the outside; and a second discharge section through which the floating oil separated in the storage section flows out to the outside, the first discharge section being formed to extend horizontally relative to a main body partition which forms the storage section, and comprising: a first inlet opening through which the coolant flows in; a buffer section in which the coolant flowing in from the inlet opening accumulates; and a first discharge outlet being formed relative to an outer partition which forms the buffer section on the outside of the main body partition, and through which the coolant is discharged to the outside.

5. A coolant tank according to claim 4, wherein a flow passage cross-sectional area of ​​said first inlet opening is larger than a flow passage cross-sectional area of ​​said first outlet opening.

6. A coolant tank according to claim 5, wherein said first outlet is formed by a socket to which a pipe is connected.

7. A coolant tank as described in claim 5, wherein the second discharge portion is formed to extend horizontally relative to the main body partition which forms the storage portion, and is provided with a second inlet opening through which floating oil flows in, and the lower end of the second inlet opening is set higher than the lower end of the first inlet opening.

8. A coolant tank as described in claim 4, wherein the separation tank further comprises a support portion for supporting the recovery container, and the filter is configured to be positioned closer to the first discharge portion than the second discharge portion when the recovery container is supported by the support portion.

9. A coolant tank as claimed in claim 1, further comprising: a pump provided in the middle of said liquid circulation piping; and a ventilation piping connecting the discharge side of said pump in said liquid circulation piping to an upper air layer in said storage tank.

10. The coolant tank according to claim 9, further comprising an opening / closing valve provided in said liquid circulation pipe between said pump and said discharge port.

11. A machine tool comprising: a coolant tank according to any one of claims 1 to 10; and a splash guard in which the machining area is formed.

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