Filtration system

Abstract

To achieve the wrapping of a filtration material around almost the entire circumference of rotating drums in a filtration unit and a backwashing unit, thereby doubling the filtration capacity compared to conventional wrapping angles.SOLUTION: A filtration system comprises a filtration unit 10 and a backwashing unit. The filtration unit wraps a filtration material F around a first rotating drum 12 inside a first tank 11, the first rotating drum allowing fluid communication between the inside and the outside. The filtration unit runs the filtration material and introduces a treated liquid outside the first rotating drum with the liquid level being above the first rotating drum 12. The filtration unit creates a negative pressure inside the rotating drum, so that the liquid is drawn through the filtration material F, thereby the filtration material F capturing solids. The backwashing unit has the same structure as the filtration unit 10, and reverses and wraps the filtration material F around a second rotating drum 22, thereby detaching the captured solids from the filtration material F so as to restore the filtration function. Wrapping guide rails 14, 14, 24, 24 are provided to ensure that the filtration material F is wrapped around almost the entire circumference of the rotating drums. Additionally, sealing members 15, 25 are mounted on the inner surface of the rotating drums to prevent the liquid from entering the rotating drums.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to a filtration system capable of removing solid and oily impurities from an aqueous liquid. [Background technology]

[0002] In grinding processes using grinding machine tools such as grinding machines that use grinding wheels to cut steel materials, coolant is supplied to prevent seizure and discoloration on the processed surface of the workpiece. The coolant after grinding contains solid matter such as cutting chips from the grinding process and abrasive grains that have come off the grinding wheel (collectively referred to as sludge below), as well as impure oils such as lubricating oil and rust-preventive oil. Continued use of coolant will cause a decrease in grinding accuracy, and ultimately a decrease in the processing quality of the workpiece.

[0003] For this reason, grinding machine tools are equipped with sludge removal equipment to separate and remove solids such as sludge contained in the coolant, and oil-water separation equipment to remove impure oil. Sludge removal equipment and oil-water separation equipment are required not only in grinding machine tools, but also in cutting machine tools.

[0004] The symbols used in the following description of Patent Document 1 are the same as those used in each patent document.

[0005] The cutting fluid impurity removal device 100 shown in Patent Document 1 includes a filtration tank unit 10, a sludge tank unit 20, a backwash tank unit 30, a two-phase separation unit 40, a filter paper supply unit (filter material traveling means) 50, a filter paper take-up unit (filter material traveling means) 60, a chamber unit 70, a water supply pump 80A and a vacuum pump 80B for supplying coolant liquid, a distribution board 81, and a frame 82 for supporting these (see Figures 1 and 2).

[0006] A roll of filter paper 200 is attached to the reel 51 of the filter paper supply unit 50. The filter paper 200 pulled out from the reel 51 passes through the filtration tank unit 10, the sludge tank unit 20, and the backwash tank unit 30, and is wound up on the reel 61 of the filter paper winding unit 60 (see FIG. 3). [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Patent No. 6865938 Summary of the Invention [Problem to be solved by the invention]

[0008] In the filtration system of Patent Document 1, the filter paper can be wound around less than half of the rotating drum of the filtration unit and backwashing unit, and therefore the filtration capacity cannot be increased.

[0009] The present invention has been made to solve the above-mentioned problems, and aims to provide a filtration system which can wrap filtration material almost entirely around the rotating drums of the filtration unit and backwash unit, and which can obtain approximately twice the filtration capacity of conventional systems when the running speed of the filtration material is the same as conventional systems, and which can halve the filtration time, becoming approximately the same as conventional systems, when the running speed of the filtration material is doubled. [Means for solving the problem]

[0010] The filtration system according to the first aspect of the present invention comprises, as main components, a filtration unit and a backwash tank unit.

[0011] The filtration unit has a first tank, and a first rotating drum within the first tank that is freely rotatable around a horizontal axis, and has a mesh and / or slits over almost the entire surface of the cylindrical portion so that flow can pass between the inside and outside of the first rotating drum, and the inside of the cylinder is made negative pressure by a negative pressure generating means outside the tank, and a continuous filter paper is wrapped around the cylindrical portion so as to cover the mesh and / or slits, and the first rotating drum is rotated together with the first rotating drum to run the filter paper, and a liquid to be treated containing solids is introduced within the first tank and outside the first rotating drum, the liquid level is raised above the first rotating drum, negative pressure is created within the cylinder by the negative pressure generating means, the liquid to be treated is passed through the filter paper by a negative pressure suction method, solids contained in the liquid to be treated are captured by the filter paper, and the liquid to be treated in the first rotating drum from which the solids have been removed is removed outside the tank.

[0012] The backwash tank unit has a second tank and a second rotating drum in the second tank that is free to rotate around a horizontal axis, and has mesh and / or slits on almost the entire surface of the cylindrical part, so that the inside and outside of the second rotating drum can flow through, and the inside of the cylindrical part is made negative pressure by a cleaning water circulating means having a negative pressure generating function outside the tank. The continuous filter paper that has captured solid matter during the filtration process in the filtration unit is turned upside down and introduced into the second tank, the filter paper is wrapped around the cylindrical part so as to cover the mesh and / or slits, and the second rotating drum is rotated together with the filter paper to run the filter paper. a cleaning water circulating means for circulating the cleaning water through the filter paper by a negative pressure suction method, and solids are separated and captured from the filter paper to regenerate the filtering function of the filter paper; the filter paper is wound up outside the second tank; and the used cleaning water containing solids in the second rotating drum is removed outside the tank, and the cleaning water from which solids have been removed is passed through a solid-liquid separator which separates the cleaning water from the solids. The cleaning water is then introduced again into the second tank.

[0013] Furthermore, in the filtration system according to the first aspect of the present invention, the filtration unit and the backwash tank unit have the following characteristic configurations.

[0014] The filtration unit has two winding guide rolls extending axially near both sides of the first rotating drum, with the center of the gap being directly above the first rotating drum, and the continuous filter paper is hung on one of the winding guide rolls, then wrapped around the outer peripheral surface of the first rotating drum and hung on the other winding guide roll, and led out of the first tank.A first blocking member having an arcuate surface identical to the inner diameter of the first rotating drum is fixedly installed inside the first tank, and the arcuate surface of the first blocking member is placed in sliding contact with the mesh and / or slit portion on the upper side of the first rotating drum around which the continuous filter paper is not wrapped, thereby preventing the intrusion of the treated liquid and maintaining a negative pressure inside the first rotating drum.

[0015] The backwash tank unit has two winding guide rolls extending axially near both sides with the center of the gap directly above the second rotating drum, and the continuous filter paper is hung on one of the winding guide rolls, then wrapped around the outer peripheral surface of the second rotating drum and hung on the other winding guide roll, and led out of the second tank.A second blocking member having an arcuate surface identical to the inner diameter of the second rotating drum is fixedly installed in the second tank, and the arcuate surface of the second blocking member is placed in sliding contact with the upper mesh and / or slit portion of the second rotating drum around which the continuous filter paper is not wrapped, thereby preventing the intrusion of the cleaning water and maintaining a negative pressure inside the first rotating drum.

[0016] The filtration system according to the second aspect of the present invention has the following characteristic features with respect to the filtration unit and the backwash tank unit in addition to the configuration of the first aspect of the present invention. That is, a first fixed shaft that passes through the center of the first rotating drum, penetrates both end faces of the first rotating drum, and is fixed at both ends to the side walls of the first tank; and the liquid to be treated in the first tank is sucked under negative pressure from outside the tank through a liquid passage formed from the middle of the first fixed shaft to the shaft end, The second tank also has a second fixed shaft that passes through the center of the second rotating drum, penetrates both end faces of the second rotating drum, and is fixed at both ends to the side walls of the second tank, and the cleaning water in the second tank is sucked under negative pressure from outside the tank through a liquid passage formed from the middle of the second fixed shaft to the shaft end.

[0017] The filtration system according to the third aspect of the present invention has the following characteristic features with respect to the filtration unit and the backwash tank unit in addition to the configuration of the second aspect of the present invention. That is, The first blocking member is supported by a first support portion provided by the first fixed shaft, and the second blocking member is supported by a second support portion provided by the second fixed shaft.

[0018] The filtration system according to the fourth aspect of the present invention has the following characteristic features with respect to the filtration unit and the backwash tank unit in addition to the configuration of the third aspect of the present invention. That is, The rotary drum has two first belt tensioning rolls extending in the axial direction at a position sandwiching the first closing member, and further has a first endless belt surrounding the first closing member and the two first belt tensioning rolls, the first endless belt contacting the inner surface of the first rotating drum and moving with the rotation of the first rotating drum and sliding against the first closing member, The drum also has two second belt tensioning rolls extending axially at a position sandwiching the second blocking member, and further has a second endless belt surrounding the second blocking member and the two second belt tensioning rolls, the second endless belt contacting the inner surface of the second rotating drum and moving as the second rotating drum rotates and sliding against the second blocking member.

[0019] The filtration system according to the fifth aspect of the present invention has the following characteristic features in addition to the features of the first aspect of the present invention. The treated liquid introduced into the filtration unit is used coolant liquid in a used coolant liquid storage tank of the machine tool, and the treated liquid from which solids have been removed and which is removed from the first rotating drum to the outside of the tank is returned to the coolant liquid supply tank of the machine tool for reuse.

[0020] The filtration system according to the sixth aspect of the present invention has the following characteristic configuration for the negative pressure generating means in addition to the configuration of the first aspect of the present invention. The negative pressure generating means includes a third tank of a sealed structure having a liquid inlet and a liquid outlet at the bottom, the liquid to be treated in the first rotating drum is introduced into the liquid inlet at the bottom, and the liquid outlet is connected to return the liquid for reuse in the machine tool. The top of the third tank is connected to a vacuum pump, and the air pressure at the top of the third tank is kept as required lower than the air pressure in the first rotating drum.

[0021] The filtration system according to the seventh aspect of the present invention has the following characteristic configuration for the cleaning water circulating means in addition to the configuration of the first aspect of the invention. The cleaning water circulating means includes a fourth tank of a sealed structure having a solid-liquid separation function for separating cleaning water from solid matter in the cleaning water, and a circulation pump for circulating the used cleaning water containing solid matter in the second rotating drum through the fourth tank and back to the second tank.

[0022] The filtration system according to the eighth aspect of the present invention has the following characteristic configuration for the fourth tank in addition to the configuration of the seventh aspect of the present invention. The fourth tank has an upper half which is a cylindrical portion and a lower half which is a conical portion with a larger diameter at the top, and has a circular plate portion which extends toward the inner circumference corresponding to the boundary between the cylindrical portion and the conical portion, and further has either a liquid inlet or a liquid outlet in the conical portion, and the other of the liquid inlet and liquid outlet has a liquid outlet at the top of the cylindrical portion, and further has the liquid inlet and liquid outlet facing in a tangential direction as components which perform the solid-liquid separation function.

[0023] The filtration system according to the ninth aspect of the present invention has the following characteristic configuration for the fourth tank in addition to the configuration of the seventh aspect of the present invention. The fourth tank has one or more mesh filters that divide the tank interior, and a liquid inlet, liquid outlet, and drain port located on both sides of the mesh filter. Used cleaning water containing solids in the second rotating drum is introduced through the liquid inlet, and the cleaning water from which solids have been removed is separated into solid and liquid by the mesh filter and flows out from the liquid outlet. When solids that cannot pass through the mesh filter and sink to the bottom of the tank have accumulated as required, they are removed from the drain port.

[0024] The filtration system according to the tenth aspect of the present invention has the following characteristic configuration for the fourth tank in addition to the configuration of the seventh aspect of the present invention. The fourth tank has a magnetic roll that rotates inside the tank, a doctor blade that slides against the magnetic roll, and a liquid inlet, liquid outlet, and drain port located on both sides of the top of the tank, and used cleaning water containing solids from the second rotating drum is introduced through the liquid inlet, the solids are magnetically attracted by the magnetic roll, the magnetically attracted solids are scraped off by the doctor blade and guided to settle to the bottom of the tank, the cleaning water flows out from the liquid outlet, and when the solids that have settled on the bottom of the tank have accumulated to the required amount, they are removed from the drain port.

[0025] The filtration system according to the eleventh aspect of the present invention has the following characteristic configuration for the fourth tank in addition to the configuration of the seventh aspect of the present invention. That is, The fourth tank has an upper half which is cylindrical and a lower half which is conical with a larger diameter at the top, and has a liquid inlet at the top of the cylindrical part, and a liquid outlet at the lower end of a short tube which penetrates the centre of the top surface of the cylindrical part and hangs down into the cylindrical part, and as a component which exerts the solid-liquid separation function, the liquid inlet is provided in the tangential direction of the cylindrical part, so that washing water flows into the tank in the inner circumferential direction and flows down in a spiral shape to the bottom of the conical part, leaving solids contained in the washing water at the bottom of the conical part, and the washing water flows out of the tank from the liquid outlet.

[0026] The filtration system according to the twelfth aspect of the present invention has a characteristic configuration in that, in addition to the configuration of the fifth aspect of the invention, the filtration system includes the following waste slag receiving tank. Prior to introducing the used coolant into the first tank, a waste slag receiving tank is provided which captures and separates solids larger than those captured by the filter paper in the filtration unit by utilizing sedimentation, and the waste slag receiving tank comprises a fifth tank and a mesh filter horizontally installed in three tiers, upper, middle and lower tiers, in close contact with the inner periphery of the fifth tank, with the mesh sizes being coarse for the upper tier, fine for the lower tier and finer for the middle tier between the upper and lower tiers, and an inlet and outlet for the used coolant are provided at two locations spaced apart from each other above the upper tier mesh filter of the fifth tank.

[0027] The filtration system according to the thirteenth aspect of the present invention has the following characteristic features regarding the mesh filter of the slag receiving tank in addition to the features of the twelfth aspect of the present invention. That is, The mesh filters arranged horizontally in a plurality of stages are provided with larger meshes at the upper positions.

[0028] The filtration system according to the fourteenth aspect of the present invention has the following characteristic features regarding the mesh filter of the slag receiving tank in addition to the features of the twelfth aspect of the present invention. That is, The mesh filters arranged in multiple tiers are arranged in three tiers, an upper tier, a middle tier, and a lower tier, with the mesh sizes being coarse for the upper tier, fine for the lower tier, and a finer grade for the middle tier that is intermediate between the upper and lower tiers, and the inlet and outlet are provided at two locations separated from each other and above the upper tier mesh filter of the fifth tank.

[0029] The filtration system according to the fifteenth aspect of the present invention has the following characteristic configuration for the slag receiving tank in addition to the configuration of the twelfth aspect of the present invention. That is, The slag receiving tank has a spray pipe located at the center of the fifth tank, and a solid capture table consisting of a mesh filter with a mesh size equal to or finer than that of the lower mesh filter, held by a frame 54b, above the upper mesh filter. The spray pipe penetrates the center of the three tiers of mesh filters, with the lower end of the pipe located near the bottom of the tank, and air is flowed into the lower part of the pipe from an air supply pipe of an air supply means provided outside the fifth tank, so that solids that settle near the bottom of the tank as the air rises are lifted up and overflow from the upper end of the pipe together with cleaning water, and the mesh filter of the fine solid capture means is arranged in a state surrounding the upper part of the spray pipe.

[0030] The filtration system according to the sixteenth aspect of the present invention has a characteristic configuration in that, in addition to the configuration of the twelfth aspect of the present invention, the filtration system includes the following magnetic adsorption type solid separation device. A magnetic adsorption type solid separation device is provided downstream of the slag receiving tank and upstream of the first tank with respect to the flow path of the used coolant liquid, and the magnetic adsorption type solid separation device has a rotating magnetic roll, a doctor blade that slides against the magnetic roll, and a solid recovery tank, and is configured to bring the coolant liquid treated in the slag receiving tank into contact with the magnetic roll to adsorb magnetically attracted solid matter to the magnetic roll, and further to scrape off the solid matter adsorbed to the magnetic roll with the doctor blade and recover it in the solid recovery tank.

[0031] The filtration system according to the seventeenth aspect of the present invention has a characteristic configuration in that, in addition to the configuration of the twelfth aspect of the invention, the filtration system is provided with the following sorting conveyor. That is, Prior to the stage of introducing the used coolant into the first tank, a separating conveyor is provided upstream of the dregs receiving tank, which can transport and separate lumpy solid matter by means of a moving conveyor belt when the used coolant flows down onto the moving conveyor belt.

[0032] The filtration system according to the eighteenth aspect of the present invention has a characteristic configuration in that, in addition to the configuration of the fifth aspect of the invention, it includes the following two-phase separation unit. If the used coolant contains oily impurities, a two-phase separation unit equipped with a hydrophilic / oleophobic filter that divides the inside of the tank into a liquid inlet side and a liquid outlet side is provided at a rear position relative to the filtration unit, and the coolant and oily impurities are separated by the two-phase separation unit. Effect of the Invention

[0033] According to the present invention, it is possible to realize a filtration system in which the filtration material can be wrapped almost entirely around the rotating drums of the filtration unit and the backwash unit, and when the running speed of the filtration material is the same as in the conventional system, a filtration capacity that is approximately twice as high as in the conventional system can be obtained, and when the running speed of the filtration material is doubled, the filtration time becomes approximately the same as in the conventional system, thereby halving the filtration time. [Brief description of the drawings]

[0034] [Figure 1] FIG. 2 is a piping diagram showing a path of a coolant liquid in the filtration system according to the embodiment of the present invention. [Diagram 2] 1 is a diagram showing a three-dimensional arrangement of a filtration unit and a backwash unit constituting a filtration system according to an embodiment of the present invention, including devices associated with both units. FIG. [Diagram 3] FIG. 2 is a diagram showing a filtration unit and a backwash unit constituting the filtration system according to the embodiment of the present invention. [Figure 4] 1 is a longitudinal sectional front view showing a filtration unit according to an embodiment of the present invention. [Diagram 5] 1 is a longitudinal sectional front view showing a backwashing unit according to an embodiment of the present invention. [Figure 6] 3 is a diagram showing the principle of a negative pressure generating means associated with a filtration unit according to an embodiment of the present invention; FIG. [Figure 7] 13 shows the external structure of a fourth tank which is a component of a wash water circulating device associated with a backwash unit according to an embodiment of the present invention. [Figure 8] FIG. 2 is a diagram showing the principle of a waste slag receiving tank disposed in front of the filtration unit according to the embodiment of the present invention. [Figure 9] FIG. 8 is a diagram showing the principle of a fourth tank of a modified example that can be substituted for the fourth tank shown in FIG. 7. [Figure 10] 8 is a diagram showing in principle a fourth tank of another modified example which can be substituted for the fourth tank shown in FIG. 7. FIG. [Figure 11] 8 is a diagram showing in principle a fourth tank of another modified example which can be substituted for the fourth tank shown in FIG. 7. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0035] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an embodiment of the filtration system of the present invention will be described in detail with reference to the drawings.

[0036] [System components] As shown in FIG. 1, the filtration system 1 of this embodiment has, as essential components, a filtration unit 10 and a backwashing unit 20, a negative pressure generating means 30 associated with the filtration unit 10, and a cleaning water circulating means 40 associated with the backwashing unit 20.

[0037] The filtration system 1 is a system in which a filtration unit 10 and a backwash unit 20 are connected by piping to a used coolant storage tank m1 of the machine tool M, and removes solid matter (sludge, etc.) from the used coolant to regenerate it into clear coolant, and returns the clear coolant to a coolant supply tank m2 of the machine tool M. The coolant here is assumed to be an aqueous coolant (a coolant used by diluting the original solution with water) that is generally used in the field of machine tools.

[0038] [Transport path of treated liquid] The used coolant stored in the used coolant storage tank m1 is sent by the first liquid feed pump 91 to the liquid inlet 51a of the fifth tank 51 of the waste slag receiving tank 50. The supernatant coolant in the fifth tank 51 flows out from the liquid outlet 51b and is sent by the second liquid feed pump 92 to the liquid inlet at the top of the magnetic adsorption type solid separation device 60. The coolant in the lower tank of the magnetic adsorption type solid separation device 60 flows out from the liquid outlet of the lower tank and is sent by the third liquid feed pump 93 to the first tank 11 of the filtration unit 10. The coolant in the first rotating drum 12 of the filtration unit 10 is sent by the fourth liquid feed pump 94 to the coolant supply tank m2 of the machine tool M via the third sealed tank 31 constituting the negative pressure generating means 30.

[0039] [Schematic configuration of the filtration unit 10 and the backwashing unit 20...Figures 2 and 3] The filtration system 1 creates negative pressure inside the first rotating drum 12 and the second rotating drum 22 to run the filtration material F, and the first rotating drum 12 and the second rotating drum 22 rotate together due to the adhesion between the filtration material F and the drum.

[0040] The particle size of the sludge contained in the coolant used in the machine tool is generally 1 μm to several hundred μm. The filter material F can be appropriately selected from filter paper, filter cloth (bag-shaped), nonwoven fabric filters formed by laminating polyester fibers using spinning and drawing techniques, sponge mats, wool mats, ceramic filters, back filters, filter media, membrane filters, and the like. The filter paper used in this filtration system 1 preferably has a retained particle size of 1 μm to several hundred μm, and more preferably 1 μm to several tens of μm. Filter materials such as filter cloth (including bag-shaped) having the same retained particle size as the above can also be used.

[0041] The nonwoven fabric filter used as the filtration material F is made of, for example, polyester fibers, and can capture 0.1 μm fine particles by combining diagonally and parallelly oriented polyester fibers, can capture 10 μm fine particles by stacking and stretching only parallel-oriented polyester fibers, can capture 10 μm fine particles by stacking polyester fibers in a random, multi-directional state and stretching them, and can capture solid matter larger than the μm order, for example, several hundred μm to 5 mm.

[0042] In the filtration unit 10, as the filtration material F wraps around the first rotating drum 12 and travels, the negative pressure inside the drum causes the coolant liquid around the drum to pass through the filtration material F, while solid particles having a size of several hundred μm or less are adsorbed by the filtration material F under the negative pressure, and the clear coolant liquid that passes through the filtration material F is extracted and returned to the machine tool M.

[0043] In the backwash unit 20, the filter material F is turned upside down and wrapped around the second rotating drum 22, and as it travels, the negative pressure inside the drum causes the cleaning water around the drum to pass through the filter material F and dislodges solid matter adhering to the filter material F, regenerating the filter material F and separating the solid matter from the cleaning water that contains the solid matter by removing it from the tank and circulating it.

[0044] The filtration system 1 is preferably provided with a filtration unit 10 in which ultrafine solids of less than 1 μm to several hundred μm in size contained in the coolant are filtered using filter paper, and a slag receiving tank 50 as a pretreatment for capturing larger solids, and further preferably provided with a magnetic adsorption type solid separator 60 disposed downstream of the slag receiving tank 50.

[0045] That is, the filtration system 1 captures solid matter and processed metal powder (polishing powder, grinding powder, or cutting powder) having a size of about 0.1 to 5 mm contained in the used coolant liquid in the slag receiving tank 50, and further captures magnetic metal powder not captured in the slag receiving tank 50 in the magnetic adsorption type solid separator 60, and captures ultrafine magnetic metal powder and abrasive powder not captured by the slag receiving tank 50 and the magnetic adsorption type solid separator 60 in the filtration unit 10. Then, the filtration system 1 passes a cleaning liquid through the filter paper in the backwashing unit 20 to separate solid matter adhering to the filter paper and to make the filter paper capable of filtering again.

[0046] The filtration system 1 holds a filter paper roll formed by winding a continuous filtration material F on a rotationally driven filter paper pay-out shaft 95, pays out the filtration material F and winds it around a guide roll 13a before introducing it into the first tank 11 of the filtration unit 10 and winding it around the first rotating drum 12 by two winding guide rolls 14, 14, then the filtration material F discharged from the first tank 11 is wound around guide rolls 13b, 13c and guide rolls 23a, 23b to be introduced inside out into the second tank 21 and wound around the second rotating drum 22 by the two winding guide rolls 24, 24, and then the filtration material F discharged from the second tank 21 is wound around the guide roll 23c and wound onto the filter paper winding shaft 96. The filtration system 1 regenerates the filtering function of the filter material F using the backwash unit 20. Therefore, by stopping the operation of the system before the filter paper roll held by the filter paper pay-out shaft 95 separates from the bobbin, the pay-out of the filter material F is stopped, and the filter paper pay-out shaft 95 rewinds the filter material F, allowing the filter paper to be used repeatedly multiple times, for example 20-30 times, without having to re-tie the filter material F.

[0047] In the filtration system 1, the continuous filtration material F is wound almost entirely around the first rotating drum 12 and the second rotating drum 22, which is approximately twice the conventional winding angle. Therefore, when the running speed of the filtration material F is the same as before (when the rotation speed of the rotating drums is the same as before), the filtration time is approximately twice as long as before, the amount of solid matter attached to the filtration material F is approximately twice as much as before, and the filtration capacity is doubled. In addition, since the winding length of the filtration material F around the first rotating drum 12 and the second rotating drum 22 is approximately twice as long as before, when the running speed of the filtration material F is doubled, the filtration time is approximately the same as before, so that the filtration time can be reduced to half of the conventional time.

[0048] The cleaning water circulation means 40 includes a fourth tank 41 having a function of separating solid matter contained in the cleaning water, but is not limited to the fourth tank 41, and may be equipped with any of fourth tanks 41A, 41B, and 41C of a different structure described below that have a function of separating solid matter contained in the cleaning water.

[0049] [Detailed configuration of the filtration unit 10...Figures 3 and 4] The filtration unit 10 has a first tank 11 consisting of a cylindrical portion and an end plate portion, and a first rotating drum 12 that is free to rotate about a horizontal axis within the first tank 11. The cylindrical portion 12a has a mesh and / or slit shape on the entire circumferential surface except for both ends, which allows flow between the inside and outside of the first rotating drum 12.

[0050] The filtration unit 10 has two winding guide rolls 14, 14 extending axially near both sides of the first rotating drum 12, with the center of the gap being directly above the first rotating drum 12. A continuous filtration material F is hung on one of the winding guide rolls 14, then wound around the outer circumferential surface of the first rotating drum 12 and hung on the other winding guide roll 14 before being discharged outside the first tank 11. A first blocking member 15 having an arcuate surface identical to the inner diameter of the first rotating drum 12 is fixedly installed inside the first tank 11, and the arcuate surface of the first blocking member 15 is brought into sliding contact with the upper mesh and / or slit portion of the first rotating drum 12 around which the continuous filtration material F is not wound, thereby preventing the intrusion of the treated liquid and maintaining a negative pressure inside the first rotating drum 12.

[0051] It has a first fixed shaft 16 that passes through the center of the first rotating drum 12, penetrates the end faces 12b, 12b at both ends of the first rotating drum 12, and is fixed at both ends to the side wall of the first tank 11, and the liquid to be treated in the first tank 11 is sucked under negative pressure from outside the tank through a liquid passage 16a formed from the middle part of the first fixed shaft 16 to the end of the shaft.

[0052] The first blocking member 15 is supported by a first support portion 16 b provided on a first fixed shaft 16 .

[0053] The roller has two first belt tensioning rolls 17, 18 extending in the axial direction at a position sandwiching the first blocking member 15, and further has a first endless belt 18 surrounding the first blocking member 15 and the two first belt tensioning rolls 17, 17, and the first endless belt 18 contacts the inner surface of the first rotating drum 12 and moves with the rotation of the first rotating drum 12, sliding against the first blocking member 15. In this case, the gap between the inner peripheral surface of the first rotating drum 12 and the cylindrical surface of the first blocking member 15 is set to the thickness of the first endless belt 18 plus, for example, 0-0.2 mm, so that the first endless belt 18 can slide against the inner surface of the first rotating drum 12. In order to set the gap between the inner surface of the first rotating drum 12 and the cylindrical surface of the first blocking member 15 to the thickness of the first endless belt 18 plus, for example, 0-0.2 mm, it is preferable that the first support portion 16b is configured so that its length can be finely adjusted.

[0054] The filtration unit 10 winds a continuous filter material F around the cylindrical portion 12a so as to cover the mesh and / or slits, rotates the first rotating drum 12 together with the filter material F, introduces the liquid to be treated (coolant liquid) containing solids into the first tank 11 and outside the first rotating drum 12, and places the liquid level above the first rotating drum 12, creates a negative pressure inside the cylinder with the negative pressure generating means 30, and passes the liquid to be treated through the filter material F by a negative pressure suction method, captures the solids contained in the liquid to be treated with the filter material F, and takes out the liquid to be treated in the first rotating drum 12 from which the solids have been removed outside the tank. The liquid level of the liquid to be treated in the first tank 11 is managed by the coordinated control of a high level sensor, a low level sensor, and the amount of liquid supplied by a pump. The mesh is a regular or oblique row of round holes, and it is preferable that the diameter of the round holes is 2 mm and the distance between the round holes is 3 mm. When slits are provided, it is preferable that they are arranged in a staggered pattern with a width of 2 mm and a length of 50 mm.

[0055] [Negative pressure generating means 30...Figure 6] The negative pressure generating means 30 comprises a third tank 31 of a sealed structure having a liquid inlet 31a and a liquid outlet 31b at the bottom, the liquid inlet 31a being adapted to introduce the liquid to be treated in the first rotating drum 12 at the bottom, and the liquid outlet 31b being connected to return the liquid for reuse in the machine tool M. The top of the third tank 31 is connected to a vacuum pump 32, and the air pressure at the top of the third tank 31 is kept as required lower than the air pressure in the first rotating drum 12.

[0056] [Details of the backwashing unit 20: Figures 3 and 5] The backwashing unit 20 has a similar structure to the filtration unit 10 . The backwash unit 20 has a second tank 21 and a second rotating drum 22 that is free to rotate around a horizontal axis within the second tank 21, and has mesh and / or slits over almost the entire surface of the cylindrical portion 22a, allowing flow between the inside and outside of the second rotating drum 22, and has a structure in which negative pressure is created inside the cylindrical body by cleaning water circulating means 40 having a negative pressure generating function outside the tank.

[0057] The backwash unit 20 has two winding guide rolls 23, 24 extending axially near both sides of the second rotating drum 22, with the center of the gap directly above the second rotating drum 22. The continuous filtration material F is hung on one of the winding guide rolls 23, then wound around the outer circumferential surface of the second rotating drum 22 and hung on the other winding guide roll 24 to be led out of the second tank 21. A second blocking member 25 having an arcuate surface identical to the inner diameter of the second rotating drum 22 is fixedly installed in the second tank 21, and the arcuate surface of the second blocking member 25 is placed in sliding contact with the upper mesh and / or slit portion of the second rotating drum 22 on which the continuous filtration material F is not wound, thereby preventing the intrusion of cleaning water and maintaining a negative pressure inside the first rotating drum 12.

[0058] It has a second fixed shaft 26 that passes through the center of the second rotating drum 22, penetrates the end face portions 22b, 22b at both ends of the second rotating drum 22, and is fixed at both ends to the side wall of the second tank 21. The cleaning water in the second tank 21 is sucked under negative pressure from outside the tank through a liquid passage 26a formed from the middle part of the second fixed shaft 26 to the shaft end.

[0059] The second blocking member 25 is supported by a second support portion 26b provided on the second fixed shaft 26.

[0060] The second closing member 25 is sandwiched between two second belt tensioning rolls 27, 28 extending in the axial direction, and further includes a second endless belt 29 surrounding the second closing member 25 and the two second belt tensioning rolls 27, 28. The second endless belt 29 contacts the inner surface of the second rotating drum 22 and moves with the rotation of the second rotating drum 22, sliding against the second closing member 25. In this case, the gap between the inner circumferential surface of the second rotating drum 12 and the cylindrical surface of the second closing member 25 is set to the thickness of the second endless belt 28 plus, for example, 0-0.2 mm, so that the second endless belt 28 can slide against the inner surface of the second rotating drum 22. In order to set the gap between the inner surface of the second rotating drum 22 and the cylindrical surface of the second blocking member 25 to the thickness of the second endless belt 28 plus, for example, 0-0.2 mm, it is preferable that the second support portion 26b is configured so that its length can be finely adjusted.

[0061] The first closing member 15 and the second closing member 25 are made of a plastic material that is flexible, has high tensile strength, and is not subject to elongation deformation, and aramid fiber is particularly preferred.

[0062] [Washing water circulating means 40...Fig. 1, Fig. 7] The cleaning water circulating means 40 includes a fourth tank 41 of a sealed structure having a solid-liquid separation function for separating the cleaning water from solid matter in the cleaning water, and a circulation pump 42 for circulating the used cleaning water containing solid matter in the second rotating drum 22 through the fourth tank 41 and returning it to the second tank 21.

[0063] The fourth tank 41 has a cylindrical portion 41a in the upper half and a conical portion 41b in the lower half, the upper side of which is a larger diameter, a circular plate portion 41c that projects to the inner circumference corresponding to the boundary between the cylindrical portion 41a and the conical portion 41b, a liquid inlet 41d in the conical portion 41b, and a liquid outlet 41e at the top of the cylindrical portion 41a. The liquid inlet 41d and the liquid outlet 41e are provided in the tangential direction as components that perform a solid-liquid separation function. As a result, the cleaning water flows from the liquid inlet 41d to the bottom of the tank in the inner circumference direction, rises in a spiral shape, and flows out of the tank from the liquid outlet 41e. The solids contained in the cleaning water rise in a spiral shape along the inner surface of the conical portion 41b, come into contact with the circular plate portion 41c, bounce back, and are left at the bottom of the tank. The solids left at the bottom of the conical portion 41b are periodically discharged as drainage. In addition, the liquid inlet 41d and the cylindrical portion 41a may be used in such a manner that the inflow and outflow are reversed. That is, the liquid inlet may be provided in the cylindrical portion 41a, the liquid outlet may be provided at the top of the conical portion 41b, and the liquid inlet and the liquid outlet may be provided in the tangential direction.

[0064] In the backwashing unit 20, the continuous filtration material F that has captured solid matter during the filtration process in the filtration unit 10 is turned upside down and introduced into the second tank 21, the filtration material F is wrapped around the cylindrical portion 22a so as to cover the mesh and / or slits, and the second rotating drum 22 is rotated together with the second rotating drum 22 to run the filtration material F. At the same time, cleaning water returning from the cleaning water circulating means 40 is introduced to the outside of the second rotating drum 22, and the liquid level is made higher than that of the first rotating drum 12, and the inside of the second rotating drum 22 is made negative pressure by the cleaning water circulating means 40 outside the tank, the cleaning water is passed through the filtration material F by a negative pressure suction method, the solid matter is separated and captured from the filtration material F, and the filtration function of the filtration material F is regenerated, the filtration material F is wound up outside the second tank 21, and the used cleaning water containing solid matter in the second rotating drum 22 is taken out of the tank, the solid matter and the cleaning water are separated, and the cleaning water from which the solid matter has been removed is introduced again into the second tank 21. The liquid level of the cleaning liquid in the second tank 21 is managed by a high level sensor, a low level sensor, and the coordinated control of the amount of liquid supplied by the pump.

[0065] [Slag receiving tank 50...Figure 8] The slag receiving tank 50 is provided to capture and separate solids larger than those captured by the filtering medium F in the filtration unit 10 by utilizing a settling action before the used coolant liquid is introduced into the first tank 11. The slag receiving tank 50 includes a fifth tank 51 and mesh filters 52a, 52b, and 52c horizontally arranged in three stages in close contact with the inner periphery of the fifth tank 51. The mesh filters may be horizontally arranged in one stage, two stages, or four or more stages.

[0066] The mesh filters 52a, 52b, and 52c are arranged in three tiers, with the mesh size increasing with increasing height. For example, the mesh filter 52a in the upper tier is a coarse grade with a mesh size of 3-5 mm that captures solid matter, the mesh filter 52b in the middle tier is a medium grade with a mesh size of 2-3 mm that captures solid matter, and the mesh filter 52c in the lower tier is a fine grade with a mesh size of 1-2 mm that captures solid matter. The mesh filters arranged in multiple tiers are arranged with the mesh size increasing with increasing height. The mesh filters may be arranged in one or two tiers.

[0067] A liquid inlet 51a for used coolant liquid is provided at a required position above the upper mesh filter 52a of the fifth tank 51, and a liquid outlet 51b is provided at the upper end of the tank on the opposite side of the liquid inlet 51a. The liquid level of the coolant liquid introduced into the fifth tank 51 is managed by the coordinated control of a high level sensor and the amount of liquid supplied by a pump so that the liquid level is above the liquid inlet 51a.

[0068] Furthermore, the fifth tank 51 has a water spout pipe 53 at the center thereof, and a solid capture table 54 consisting of a mesh filter 54a, the mesh size of which is equal to or smaller than that of the lower mesh filter 52c, held by a frame 54b above the upper mesh filter 52a, the water spout pipe 53 penetrating the center of the three mesh filters, the lower end of the pipe being located near the bottom of the tank, air being introduced into the lower part of the pipe from an air supply pipe 55 of an air supply means provided outside the fifth tank 51, so that as the air rises, solids that settle near the bottom of the tank overflow from the upper end of the suction pipe together with cleaning water, and the water spout pipe 53 is provided so as to penetrate the center of the solid capture table 54. As a result, solids that settle to the bottom of the tank and are approximately 0.5 to 1·5 mm in size are captured by the mesh filter 54a. The waste sludge receiving tank 50 cannot capture solid matter (sludge) having a size of approximately 1 μm to several hundred μm.

[0069] [Magnetic adsorption type solids separator...Figure 1] The magnetic adsorption type solid separator 60 is provided downstream of the waste slag receiving tank 50 and upstream of the first tank 10 in relation to the flow path of the used coolant. The magnetic adsorption type solid separator 60 has a rotating magnet roll 61, a doctor blade 62 in sliding contact with the magnet roll 61, and a solid recovery tank 63, and is configured to bring the coolant treated in the waste slag receiving tank 50 into contact with the magnet roll 61 to cause magnetically attractive solid matter to be attracted to the magnet roll, and further scrape off the solid matter attracted to the magnet roll 61 with the doctor blade 62 and recover it in the solid recovery tank 63. The magnetic adsorption type solid separator 60 is a commercially available product.

[0070] [Drain of each tank] A drain port is provided at the lower end of each of the first to fifth tanks 11, 21, 31, 41, and 51, and each drain port is provided with a drain valve 81, 82, 83, 84, and 85 that can be opened and closed manually. The drain pipe downstream of each drain valve is connected to a sludge tank 86 (prepared on the factory side).

[0071] [Variations] [Variation 1 regarding the fourth tank 41] A fourth tank 41A shown in Fig. 9 may be provided instead of the fourth tank 41 shown in Fig. 7. The fourth tank 41A has one or more mesh filters 41f that divide the inside of the tank, and a liquid inlet 41g, a liquid outlet 41h, and a drain port 41i located on both sides of the mesh filter 41f, and the used washing water containing solids in the second rotating drum 22 is introduced from the liquid inlet 41g and separated into solid and liquid by the mesh filter 41f, and the washing water from which the solids have been removed flows out from the liquid outlet 41h, and when the solids that cannot pass through the mesh filter 41f and settle to the bottom of the tank are accumulated as required, they are removed from the drain port 41i.

[0072] [Modification 2 regarding the fourth tank 41] A fourth tank 41B shown in Fig. 10 may be provided instead of the fourth tank 41 shown in Fig. 7. The fourth tank 41B has a magnet roll 41j rotating inside the tank, a doctor blade 41k in sliding contact with the magnet roll 41j, and a liquid inlet 41m, a liquid outlet 41n, and a drain port 41p located on both sides of the upper part of the tank, and used washing water containing solid matter in the second rotating drum 22 is introduced from the liquid inlet 41m, the solid matter is magnetically attracted by the magnet roll 41j, the magnetically attracted solid matter is scraped off by the doctor blade 41k, and guided to settle to the bottom of the tank, the washing water flows out from the liquid outlet 41n, and when the solid matter that has settled to the bottom of the tank has accumulated to a required level, it is removed from the drain port 41p.

[0073] [Variation 3 regarding the fourth tank 41] Instead of the fourth tank 41 shown in FIG. 7, a fourth tank 41C shown in FIG. 11 may be provided. The fourth tank 41C has a cylindrical portion 41a in the upper half and a conical portion 41b in the lower half, the upper half of which is a large diameter portion. The cylindrical portion 41a has a liquid inlet 41q at the top, a liquid outlet 41r at the center of the top surface of the cylindrical portion 41a, a large diameter hanging pipe 41s hanging from the top surface into the tank has an open lower end, and the liquid inlet 41q is provided in the tangential direction of the cylindrical portion 41a as a component that exerts a solid-liquid separation function. This allows the washing water to flow in the inner circumferential direction into the tank and flow down in a spiral shape to the bottom of the conical portion 41b, leaving solids contained in the washing water at the bottom of the conical portion 41b, and the washing water to flow out of the tank from the liquid outlet 41r. When the solids that settle at the bottom of the tank are accumulated as required, they are removed from the drain port 41t.

[0074] [Addition of chip separation conveyor] The piping diagram of the filtration system 1 shown in Fig. 1 does not include a chip separating conveyor. However, when a machine tool M that performs cutting discharges a large amount of chips larger than the solids of a size appropriate for capture in the waste slag receiving tank 50, the filtration system 1 is preferably configured to have a separating conveyor that separates and removes chips contained in the used coolant between the used coolant storage tank m1 and the waste slag receiving tank 50. The separating conveyor is disposed upstream of the waste slag receiving tank 50 in a stage before the used coolant is introduced into the first tank 10, and is equipped with a separating conveyor that can transport and separate clumpy solids by the conveyor belt when the used coolant flows down onto the traveling conveyor belt.

[0075] [Addition of two-phase separation unit] When oily impurities are contained in the used coolant, it is preferable that the filtration system 1 is configured such that a two-phase separation unit is disposed downstream of the filtration unit 10. Although not included in the piping diagram of Fig. 1, when oily impurities are contained in the used coolant, a two-phase separation unit is provided. The two-phase separation unit is provided with a hydrophilic / oleophobic filter disposed downstream of the filtration unit 10, which divides the inside of the tank into a liquid inlet side and a liquid outlet side in a vertical wall shape, and the coolant flows through the hydrophilic / oleophobic filter, and the oily impurities are captured by the hydrophilic / oleophobic filter.

[0076] In the above embodiment, the present invention has been described as being applied to a device for removing solid impurities from coolant liquid used in machine tools, but the filtration system of the present application can be widely used as a device for removing solid impurities and oily impurities contained in various aqueous liquids such as industrial wastewater, domestic wastewater, etc. In this case, it is only necessary to replace the filter material depending on the type of solid impurities or oily impurities, and there is no need to replace mechanical parts. [Explanation of symbols]

[0077] 1. Filtration system 10…Filtration unit 11…First tank 12…First rotating drum 12a...Cylindrical part 12b...End face part 13a, 13b, 13c...Guide rolls 14…Winding guide roll 15...First blocking member 16…First fixed axis 16a...Liquid passage 16b...First support part 17…First belt tensioning roll 18…First endless belt 20…Backwash unit 21…Second tank 22…Second rotating drum 22a...Cylindrical part 22b...end face part 23a, 23b, 23c...Guide rolls 24…Winding guide roll 25...Second blocking member 26…Second fixed axis 26a...Liquid passage 26b...Second support part 27…First belt tensioning roll 28…Second endless belt 30...Negative pressure generating means 31…Third sealed tank 31a...liquid inlet 31b…liquid outlet 32…Vacuum pump 40...Cleaning water circulation means 41, 41A, 41B, 41C...4th tank 41a...Cylindrical part 41b…cone section 41c…Annular plate section 41d...Liquid inlet 41e…Liquid outlet 41f…Mesh filter 41g…liquid inlet 41h…Liquid outlet 41i…Drain port 41j…Magnet roll 41k…Doctor Blade 41m…liquid inlet 41n…liquid outlet 41p…Drain port 41q…liquid inlet 41r…liquid outlet 42…Circulation pump 50...Slag receiving tank 51…5th tank 51a...Liquid inlet 51b…Liquid outlet 52a, 52b, 52c...Mesh filters 53…Fountain pipe 54…Solids capture table 54a…Mesh filter 54b…frame body 55…Air supply pipe 60...Magnetic adsorption type solids separator 61...Magnet roll 62...Doctor Blade 63...Solids collection tank 81, 82, 83, 84, 85...Drain valve 86…Sludge tank 91…First liquid delivery pump 92…Second liquid delivery pump 93…Third liquid delivery pump 94…Fourth liquid delivery pump 95...Filter paper feed shaft 96…Filter paper winding shaft F…filter paper M…Machine tool m1…used coolant storage tank m2…Coolant supply tank

Claims

1. a filtration unit having a structure in which a first tank, a first rotating drum which is free to rotate around a horizontal axis within the first tank, and a mesh and / or slits on substantially the entire surface of a cylindrical portion thereof, so that the inside and outside of the first rotating drum can flow through the first tank and a negative pressure is generated within the cylindrical portion by a negative pressure generating means outside the tank, a continuous filtering material is wrapped around the cylindrical portion so as to cover the mesh and / or slits, and the first rotating drum is rotated together with the first rotating drum to run the filtering material, a liquid to be treated which contains solid matter is introduced within the first tank and outside the first rotating drum, the liquid level is set above the first rotating drum, the inside of the cylinder is made negative pressure by the negative pressure generating means, the liquid to be treated is passed through the filtering material by a negative pressure suction method, solid matter contained in the liquid to be treated is captured by the filtering material, and the liquid to be treated in the first rotating drum from which the solid matter has been removed is taken out of the tank; A structure having a second tank, and a second rotating drum that is free to rotate around a horizontal axis within the second tank, and a mesh and / or slits on substantially the entire surface of a cylindrical portion to allow flow between the inside and outside of the second rotating drum, and a negative pressure is created within the cylindrical portion by a cleaning water circulating means having a negative pressure generating function outside the tank, and the continuous filtration material that has captured solid matter during the filtration process in the filtration unit is introduced into the second tank with the front and back turned over, the filtration material is wrapped around the cylindrical portion so as to cover the mesh and / or slits, and the second rotating drum is rotated together with the filtration material to run the filtration material and to rotate the filtration material forward. a backwash tank unit for introducing the washing water returning from the washing water circulation means to the outside of the second rotating drum, setting the liquid level above that of the first rotating drum, creating a negative pressure inside the second rotating drum by the washing water circulation means outside the tank, causing the washing water to flow through the filtration material by a negative pressure suction method, separating and capturing solids from the filtration material, regenerating the filtering function of the filtration material, and winding up the filtration material outside the second tank, and removing used washing water containing solids from the second rotating drum outside the tank, passing the used washing water containing solids through a solid-liquid separator that separates the solids from the washing water, and introducing the washing water from which the solids have been removed back into the second tank, Furthermore, the filtration unit has two winding guide rolls extending in the axial direction near both sides of the first rotating drum with the position directly above the first rotating drum as the center of the distance therebetween, and the continuous filtration material is hung on one of the winding guide rolls and then wound around the outer circumferential surface of the first rotating drum and then hung on the other winding guide roll to be led out of the first tank, and a first closing member having an arcuate surface identical to the inner diameter of the first rotating drum is fixedly provided in the first tank, and the arcuate surface of the first closing member is brought into sliding contact with the mesh and / or slit portion on the upper side of the first rotating drum on which the continuous filtration material is not wrapped, thereby preventing the intrusion of the treated liquid and maintaining a negative pressure inside the first rotating drum, The reverse cleaning tank unit has two winding guide rolls extending in the axial direction near both sides with the position directly above the second rotating drum as the center of the gap, and the continuous filtration material is hung on one of the winding guide rolls, then wound around the outer circumferential surface of the second rotating drum, and hung on the other winding guide roll to be led out of the second tank. In addition, a second blocking member having an arcuate surface identical to the inner diameter of the second rotating drum is fixedly installed in the second tank, and the arcuate surface of the second blocking member is brought into sliding contact with the mesh and / or slit portion on the upper side of the second rotating drum on which the continuous filtration material is not wound, thereby preventing the intrusion of the cleaning water and maintaining a negative pressure inside the first rotating drum. A filtration system characterized by:

2. a first fixed shaft that passes through the center of the first rotating drum, penetrates both end faces of the first rotating drum, and is fixed at both ends to the side walls of the first tank; and the liquid to be treated in the first tank is sucked under negative pressure from outside the tank through a liquid passage formed from a midpoint of the first fixed shaft to the shaft end, The second tank further includes a second fixed shaft that passes through the center of the second rotating drum, penetrates both end faces of the second rotating drum, and is fixed at both ends to the side walls of the second tank, and the cleaning water in the second tank is sucked under negative pressure from outside the tank through a liquid passage formed from the middle of the second fixed shaft to the shaft end. The filtration system of claim 1 .

3. the first blocking member is supported by a first support portion provided on the first fixed shaft, The second blocking member is supported by a second support portion provided on the second fixed shaft. The filtration system of claim 2.

4. the first belt tensioning rolls are arranged in a position sandwiching the first closing member and extending in an axial direction, and the first belt tensioning rolls are arranged to surround the first closing member and the two first belt tensioning rolls, the first endless belt contacting the inner surface of the first rotating drum and moving with the rotation of the first rotating drum and sliding against the first closing member; The rotary drum further includes two second belt tensioning rolls extending in the axial direction at a position sandwiching the second closing member, and further includes a second endless belt surrounding the second closing member and the two second belt tensioning rolls, the second endless belt contacting the inner surface of the second rotating drum and moving with the rotation of the second rotating drum and sliding against the second closing member. The filtration system of claim 3.

5. 2. The filtration system as described in claim 1, wherein the treated liquid introduced into the filtration unit is used coolant liquid in a used coolant liquid storage tank of a machine tool, and the treated liquid from which solids have been removed and which is removed from the first rotating drum to the outside of the tank is returned to the coolant liquid supply tank of the machine tool for reuse.

6. The filtration system described in claim 5, wherein the negative pressure generating means comprises a third tank of a sealed structure having a liquid inlet and a liquid outlet at the bottom, the liquid inlet being adapted to introduce the liquid to be treated in the first rotating drum at the bottom, and the liquid outlet being connected to return the liquid for reuse in the machine tool, the top of the third tank being connected to a vacuum pump, and the air pressure at the top of the third tank being maintained at a required level lower than the air pressure in the first rotating drum.

7. 6. The filtration system according to claim 5, wherein the cleaning water circulating means comprises a fourth tank of a sealed structure having a solid-liquid separation function for separating the cleaning water from solid matter in the cleaning water, and a circulation pump for circulating the used cleaning water containing the solid matter in the second rotating drum through the fourth tank and back to the second tank.

8. The filtration system according to claim 7, wherein the fourth tank has an upper half which is a cylindrical portion and a lower half which is a conical portion with a larger diameter at the top, and has a circular annular plate portion which protrudes toward the inner circumference corresponding to the boundary between the cylindrical portion and the conical portion, and further has either a liquid inlet or a liquid outlet in the conical portion, and the other of the liquid inlet and liquid outlet has a liquid outlet in an upper portion of the cylindrical portion, and further wherein the liquid inlet and the liquid outlet are provided in a tangential direction as components which exert the solid-liquid separation function.

9. The fourth tank has one or more mesh filters that divide the inside of the tank, and a liquid inlet, a liquid outlet, and a drain port located on both sides of the mesh filters, and the used cleaning water containing solids in the second rotating drum is introduced through the liquid inlet and separated into solid and liquid by the mesh filter, and the cleaning water from which the solids have been removed flows out from the liquid outlet, and when the solids which cannot pass through the mesh filter and settle to the bottom of the tank have accumulated as required, they are removed from the drain port.

10. The fourth tank has a magnetic roll rotating inside the tank, a doctor blade in sliding contact with the magnetic roll, and a liquid inlet, a liquid outlet, and a drain port located on both sides of the upper part of the tank, and the used cleaning water containing solids in the second rotating drum is introduced through the liquid inlet, the solids are magnetically attracted by the magnetic roll, the magnetically attracted solids are scraped off by the doctor blade and guided to settle to the bottom of the tank, the cleaning water flows out from the liquid outlet, and when the solids that have settled to the bottom of the tank have accumulated to a required amount, they are removed from the drain port.

11. 8. The filtration system according to claim 7, wherein the fourth tank has an upper half which is a cylindrical portion and a lower half which is a conical portion with a larger diameter at the top, has a liquid inlet at the top of the cylindrical portion, and has a liquid outlet at the lower end of a short tube which penetrates the center of the top surface of the cylindrical portion and hangs down into the cylindrical portion, and further, as a component which exerts the solid-liquid separation function, the liquid inlet is provided in a tangential direction of the cylindrical portion, so that the washing water flows into the tank in an inner circumferential direction and flows down in a spiral shape to the bottom of the conical portion, leaving solids contained in the washing water at the bottom of the conical portion, and the washing water flows out of the tank from the liquid outlet.

12. 6. The filtration system according to claim 5, further comprising a waste slag receiving tank which, prior to introducing the used coolant into the first tank, captures and separates solids larger than those captured by the filtering material in the filtering unit by utilizing sedimentation, the waste slag receiving tank comprising a fifth tank and a mesh filter horizontally mounted in three tiers, upper, middle and lower tiers, in close contact with the inner periphery of the fifth tank, the upper tier having a coarse mesh size, the lower tier having a fine mesh size, and the middle tier having a fine mesh size intermediate between the upper and lower tiers, and an inlet and an outlet for the used coolant are provided at two locations spaced apart from each other above the upper tier mesh filter of the fifth tank.

13. The filtration system according to claim 12, wherein the mesh filters arranged horizontally in a plurality of stages have larger meshes at higher positions.

14. The filtration system according to claim 12, wherein the mesh filters arranged horizontally in multiple stages are arranged in three stages, an upper stage, a middle stage and a lower stage, with the mesh sizes being coarse for the upper stage, fine for the lower stage and a finer grade for the middle stage which is intermediate between the upper and lower stages, and the inlet and the outlet are provided at two locations separated from each other and above the upper stage mesh filter of the fifth tank.

15. The slag receiving tank has a spray pipe located at the center of the fifth tank, and a solid capture table consisting of a mesh filter with a mesh size equal to or finer than that of the lower mesh filter, held by a frame body 54b above the upper mesh filter, the spray pipe penetrates the center of the three tiers of mesh filters, the lower end of the pipe is located near the bottom of the tank, and air is flowed into the lower part of the pipe from an air supply pipe of an air supply means provided outside the fifth tank, so that solids that settle near the bottom of the tank as the air rises are caused to overflow from the upper end of a suction pipe together with cleaning water, and the spray pipe 53 is arranged in a state where it penetrates the center of the solid capture table.

16. 13. The filtration system according to claim 12, further comprising a magnetic adsorption type solid separation device downstream of the slag receiving tank and upstream of the first tank in relation to a flow path of the used coolant liquid, the magnetic adsorption type solid separation device having a rotating magnetic roll, a doctor blade in sliding contact with the magnetic roll, and a solid recovery tank, the magnetic roll is brought into contact with the coolant liquid treated in the slag receiving tank to adsorb magnetically attracted solid matter to the magnetic roll, and the doctor blade is further used to scrape off the solid matter adsorbed to the magnetic roll and recover it in the solid recovery tank.

17. The filtration system according to claim 12, further comprising a separating conveyor arranged upstream of the slag receiving tank, which separates lumps of solid matter from the used coolant liquid by transporting the used coolant liquid onto a moving conveyor belt, prior to the introduction of the used coolant liquid into the first tank.

18. 6. The filtration system according to claim 5, wherein, when the used coolant contains oily impurities, a two-phase separation unit equipped with a hydrophilic / oleophobic filter that divides the inside of the tank into a liquid inlet side and a liquid outlet side is provided at a rear position relative to the filtration unit, and the coolant and oily impurities are separated by the two-phase separation unit.

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