JP2018130770A - Classification/recovery system, and working liquid cleaning system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a classification/recovery system capable of classifying and recovering particles contained in liquid by a comparatively simple constitution; and to provide a working liquid cleaning system.SOLUTION: A system for classifying and recovering particles contained in liquid, includes a conveyance route 111 for forming a channel of liquid (working liquid), a plurality of particle classification holes formed in a direction from the upstream to the downstream of the conveyance route 111, and a plurality of recovery parts 112 for recovering particles settling through each particle classification hole, respectively. Thus, particles are classified and recovered by each recovery part 112.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a classification / recovery device and a processing liquid purification system capable of classifying and recovering particles contained in a liquid.

The desire to remove some individual phase (particles, etc.) contained in the liquid is in various fields and aspects, and one of them is included in various processing liquids used in industrial production processes. There is a demand to remove particles (abrasive grains, cutting scraps, grinding scraps, other foreign matters, etc.).
Techniques relating to this are disclosed in Patent Documents 1 and 2.

JP-A-9-29636 JP-A-11-58235

As a method of removing particles in the liquid, there are a method of filtering with a filter as shown in Patent Document 1, a centrifugal separation, a sedimentation separation, and the like. As described in Patent Document 2, the sedimentation separation is also used for classifying particles in the liquid.
In the case of filtration using a paper filter, a cartridge filter or the like, the problem of filter clogging and the replacement of the filter are indispensable, which increases the running cost. Centrifugation requires a cyclone centrifuge and the like, so initial and running costs are required. In the sedimentation separation system, a large sedimentation tank has been conventionally required. Further, as described in FIG. 2 of Patent Document 2, when classification is performed by a sedimentation separation method, since a plurality of classification tanks are required, the apparatus becomes relatively large, and initial and running It was costly.

  In view of the above points, an object of the present invention is to provide a classification / recovery device and a processing liquid purification system capable of classifying and recovering particles contained in a liquid with a relatively simple configuration.

(Configuration 1)
An apparatus for classifying and recovering particles contained in a liquid, comprising: a transport path that forms a flow path for the liquid; a plurality of particle classification holes formed in an upstream to downstream direction of the transport path; and each of the particle classification holes A classification / collection device comprising: a plurality of recovery units for recovering the particles that have settled through each of the particles.

(Configuration 2)
The classifying / collecting apparatus according to Configuration 1, wherein the conveying path is inclined.

(Configuration 3)
The classifying / collecting apparatus according to Configuration 2, further comprising an inclination angle adjusting mechanism capable of adjusting the inclination angle.

(Configuration 4)
4. The classifying / collecting device according to any one of configurations 1 to 3, wherein a discharge port is provided at a lower portion of the recovery unit.

(Configuration 5)
5. The classification / collection device according to any one of configurations 1 to 4, further comprising a magnet for collecting magnetic particles in the vicinity of the particle classification hole.

(Configuration 6)
On the downstream side of the connection part of the particle classification hole and the recovery part, it protrudes to the upstream side substantially in parallel with the flow path direction of the transport path, and gradually decreases as the protrusion amount goes downward, and finally the recovery part. 6. The classification / collection device according to any one of configurations 1 to 5, wherein a rectifying member that is the same as the side wall is formed.

(Configuration 7)
The classification / recovery device according to any one of configurations 1 to 6, further comprising a fin member on a downstream side of a connection portion between the particle classification hole and the recovery portion.

(Configuration 8)
The classification / recovery device according to any one of configurations 1 to 7, further comprising a flow inhibition member that inhibits the flow of the liquid in the conveyance path.

(Configuration 9)
The liquid is a processing liquid used for grinding or cutting, and the classifying / collecting apparatus according to any one of configurations 1 to 8, a processing liquid tank provided downstream of the classifying / collecting apparatus, and the processing liquid A machining liquid purification system comprising: a microbubble generator that generates microbubbles in a tank.

  According to the classification / recovery device and the processing liquid purification system of the present invention, it is possible to provide a classification / recovery device having a relatively simple configuration formed on a conveyance path serving as a liquid flow path.

Schematic which shows the example of installation of the classification and collection | recovery apparatus of embodiment which concerns on this invention Schematic showing the classification and recovery device of the embodiment The figure which shows the result of the performance experiment of the classification and collection | recovery apparatus of embodiment Graph showing the sedimentation velocity of each particle (assuming chips, etc.) calculated using Stokes' formula Figure showing a modification to improve classification and collection efficiency Figure showing a modification to improve classification and collection efficiency Schematic showing an installation example of a classification / collection device using a processing fluid collection sheet Schematic diagram of the experimental apparatus regarding the relationship between the tilt angle and the machining fluid flow velocity Illustration of Manning's official setting conditions Graph showing the experimental results and the Manning formula calculation results on the relationship between the tilt angle and the machining fluid flow velocity

  Hereinafter, embodiments of the present invention will be specifically described with reference to the drawings. In addition, the following embodiment is one form at the time of actualizing this invention, Comprising: This invention is not limited within the range.

<Embodiment 1>
FIG. 1 is a schematic diagram illustrating an installation example of the classification / collection device of the present embodiment, and FIG. 2 is a schematic diagram illustrating the classification / collection device of the present embodiment.
The classification / recovery device 11 of this embodiment is installed as a processing liquid purification system 1 for removing chips and abrasive grains contained in a processing liquid used for grinding / polishing. As schematically shown in FIG. 1, “Supplying the processing fluid from the nozzle 32 to the processing point for supplying the processing fluid to the grindstone 21 (processing point) included in the grinding machine 2 → into the processing fluid tank 12. In the circulation system of “collecting the machining fluid → supplying the machining fluid from the machining fluid tank 12 to the nozzle 32 by the pump 31”, the collection path of the machining fluid (including chips and abrasive grains) after being supplied to the machining point A classification / collection device 11 is installed as a part of the system.

The classification / recovery device 11 includes a conveyance path 111 that forms a flow path for liquid (processing liquid, etc.), a plurality of particle classification holes 111h (see FIG. 5) formed in the upstream to downstream direction of the conveyance path 111, and each particle. A plurality of collection units 112 for collecting particles (such as chips and abrasive grains) that have settled through the classification holes 111h and a magnet for collecting magnetic particles 114 are provided.
The conveyance path 111 may be formed as a pipe-shaped closed flow path, or may be formed as a flow path whose upper portion is released in a bowl shape. Also, the cross-sectional shape of the flow path may be circular or rectangular. In this embodiment, the conveyance path 111 formed as a channel having a rectangular cross section with the upper part released is taken as an example.
As shown in FIG. 5, a plurality of particle classification holes 111h are formed in the conveyance path 111, and each recovery unit 112 is provided so as to be connected to each particle classification hole 111h. In the present embodiment, the particle classification hole 111h is a rectangular hole, and the collection unit 112 connected to the particle classification hole 111h also has a rectangular cross section (that is, the basic aspect is a substantially quadrangular prism). In addition, the shape of the particle classification hole 111h and the collection | recovery part 112 connected with this is not restricted to this, A round shape, a polygon, etc. may be sufficient.
Each collection part 112 is the same structure in this embodiment, and is provided with the discharge port 113 in the lower part. The recovery unit 112 in this embodiment has a lower portion tapered in a funnel shape, and a discharge cap 113 is formed by including a detachable cap at the tip.
The magnetic particle recovery magnet 114 is provided in the vicinity of the particle classification hole 111h. In the present embodiment, as shown in FIG.

As described above, the classification / recovery device 11 is installed as a part of the processing fluid recovery path after processing including chips, abrasive grains, and the like. Are filled with liquid (preferably the same as the working fluid circulating in the system). As a result, the machining fluid flowing on the conveyance path 111 flows on the particle classification hole 111h without being greatly disturbed by the flow.
As described above, the machining fluid flowing on the conveyance path 111 includes chips, abrasive grains, and the like. Chips, abrasive grains, and the like basically have a higher specific gravity than the machining fluid, and thus settle with time. However, since their sizes and specific gravity are different, there is a difference in settling speed. That is, among the chips and abrasive grains contained in the machining fluid flowing on the conveyance path 111, the heavier one settles faster, and therefore falls from the upstream particle classification hole 111h and accumulates in the upstream collection unit 112. It becomes. On the other hand, since the lighter one takes time for sedimentation, it is transported over a long distance on the conveyance path 111 by the flow of the processing liquid, and as a result, it falls from the downstream particle classification hole 111h and accumulates in the downstream collection unit 112. .
In the classification / recovery device 11, chips and abrasive grains are classified and recovered in this way.

Assuming that the flow of the machining fluid is gentle and there is no turbulence, the settling velocity v of particles (chips, abrasive grains, etc.) is Stokes, where particle density ρs, machining fluid density ρw, particle average diameter d, and machining fluid viscosity η From the equation
v = (ρs−ρw) gd ² / 18η Equation 1
The particles having a large particle size and density are first settled and collected. In addition, g is a gravitational acceleration.
Here, when the grindstone width of the grindstone 21 is B (m), the cutting depth is ap (m), and the feed rate of the workpiece is Vw (m / min), the grinding removal rate M per unit time is: It is given by
M = B · ap · Vw Equation 2
Therefore, when estimating the amount of chips per day in a general surface grinder operation, when ap = 10 μm / pass and Vw = 10 m / min with a B = 10 mm grindstone, grinding was performed continuously for 10 hours without air cut. In this case, the amount of chips is 0.6 × 10 ⁻³ m ³ , and it is sufficient that the capacity of the collection unit 112 for chip collection is about 1 to 3 L / day.

Next, as a performance experiment of the classification / recovery device 11, an experiment was conducted in which particles (dust) were mixed in the processing liquid, and this was classified and recovered by the classification / recovery device 11.
In the experiment, ground dust is assumed assuming particles having a random particle size, and 50000 mg of this dust is placed on a tray installed upstream of the classifying / collecting device 11, and a flow rate Q = 2L / The working fluid was supplied for 5 minutes at min and 10 L / min. In other words, an experiment was conducted in which a processing fluid containing dust having a flow rate substantially equal to this was supplied to the classification / recovery device 11.
As the classifying / collecting device 11, a device having five collecting parts 112 from P0 to P4 from the upstream side is used, and when the classifying / collecting device 11 is installed, it is inclined by 20 degrees to form a flow path. did.

The experimental results are shown in FIG.
The photograph of the dust collected by the collection part 112 of P0-P3 was shown under the FIG. As shown in the photograph, it was shown that fine dust was collected from the upstream collection unit 112 (P0) to the downstream collection unit 112 (P3), and classification was possible.
The dust in each recovery unit 112 was collected with a suction filter for SS measurement and dried to measure the weight, and the recovery rate was calculated. The result is the graph of FIG.
At a flow rate of 2 L / min, the recovery rate at the first recovery unit 112 (P0) was 97.0%, and the recovery rate of P0 at a flow rate of 10 L / min was 85.0%. The final collection rates of the classification / collection apparatus 11 were 97.2% and 98.0%, respectively. According to this experiment, 2 to 3% of remaining material flows into the machining fluid tank. However, in this experiment, ground dust was used, so substances with a specific gravity smaller than the machining fluid (dead leaves, etc.) May be included. In an actual grinding system, etc., the possibility of such substances being mixed is relatively small, and the particles that reach the machining liquid tank can be made so light and fine that they do not affect the processing. It is done.
In addition, by providing a microbubble generating device that generates microbubbles in the processing liquid tank 12 (or in a tank installed on the upstream side of the processing liquid tank), residual substances (fine particles and suspended matters) are provided. Can also be removed by microbubble flotation. In actual production sites, the spoilage of water-soluble processing fluid is regarded as a problem. By using such a processing fluid purification system equipped with a micro-bubble generator, bacteria that cause spoilage, their dead bodies, Since excreta and the like are also removed by microbubble flotation, it is possible to prevent malodor of the processing liquid and extend its life.

  Next, FIG. 4 shows the result of calculating the sedimentation speed of particles assuming chips and abrasive grains using Stokes' equation 1. The viscosity of water was used as the working fluid viscosity η. From the figure, the sedimentation speed is determined according to the order of material density. Moreover, since the sedimentation speed increases in proportion to the square of the particle diameter, large particles that adversely affect grinding can be removed preferentially. By utilizing the density difference, separation and recovery of abrasive grains (abrasive grains dropped from the grindstone 21) and chips can be expected.

As described above, according to this embodiment, a very compact classification / collection device that can be installed in the flow path between the grinding machine and the grinding fluid tank (can be installed as a part of the recovery path). 11 can collect chips and abrasive grains contained in the machining fluid. A classification / recovery device can be installed as part of the flow path to the machining fluid tank, and it is possible to prevent particles from reaching the machining fluid tank (pre-treatment), thus increasing the efficiency of filtration. And labor saving.
Furthermore, since it becomes possible to separate and collect the abrasive grains (the abrasive grains dropped from the grindstone 21) and the chips, it is easy to collect and reuse the abrasive grains such as diamond. In addition, since the magnetic particle collecting magnet 114 is provided in the vicinity of the particle classification hole 111h, the efficiency of collecting chips of magnetic material such as metal is improved.
According to this embodiment, although it is an apparatus having such a classification / recovery function, this can be realized with a simple configuration, no power is required in the operation of the classification / recovery apparatus 11, and A member such as a filter is also unnecessary. Therefore, the introduction cost can be reduced, energy is not required for classification / recovery processing operation, and it is not necessary to replace the filter as a consumable or to clean the filter. Useful for.
In addition, since each recovery unit 112 is provided with a discharge port 113 in the lower part, the classified particles can be easily recovered. For example, if this method is adopted at the production site, the actual amount of chips removed by the operation of the day can be grasped, so that it can be used for management of production processing and is very useful.

  In the present embodiment, the particle classification holes 111h and the collection parts 112 formed for classification are described as having the same shape and size. However, the particle classification holes 111h and the collection parts 112 may be different depending on the purpose of classification. May be. For example, the particle classification holes 111h for collecting the fine particles on the downstream side may be formed as long holes along the flow, etc. (the finer (lighter) particles have a lower sedimentation speed and fall. The error in time (= distance) is likely to increase.) Further, the capacity of the upstream collection unit 112 may be increased, and the capacity of the downstream collection unit 112 may be reduced.

Moreover, as illustrated in FIGS. 5 and 6, a configuration that further improves the recovery efficiency may be adopted.
FIG. 5 improves the classification / recovery efficiency of particles drifting in the liquid by providing a corner R in the portion of the weir downstream of each recovery unit 112. That is, on the downstream side of the connection part between the particle classification hole 111h and the recovery part 112, it protrudes to the upstream side substantially in parallel with the flow path direction of the transport path 111, and the protrusion amount gradually decreases as it goes downward, and finally the recovery part A straightening member 117 that is the same as the side wall of 112 was formed. As a result, as shown in the partially enlarged view of FIG. 5, since a substance having a large particle size and density is preferentially settled, classification accuracy is relatively small especially in the case of a laminar and stable flow. Becomes higher.
FIG. 6 shows a detachable separation fin (fin member) 115 provided on the weir portion on the downstream side of the connecting portion between the particle classification hole 111h and the recovery portion 112. FIG. The separation fin 115 can be arbitrarily set in height and shape, and has a shape that slightly protrudes into the conveyance path 111, thereby having the effect of dropping (sedimenting) particles into the particle classification hole 111h. is there. For example, the flow of the processing liquid may be controlled by forming the width of the separation fin 115 smaller than the width of the conveyance path 111 and changing the installation position in the width direction of the separation fin 115 in each recovery unit 112. Good. Further, the classification may be arranged by changing the height of the separation fin 115.
The rectifying member 117 shown in FIG. 5 may also be an attachment type.

Moreover, you may make it provide the flow inhibition member which inhibits the flow of the process liquid in the conveyance path 111. FIG. The flow rate and flow rate of the working fluid in the conveyance path 111 are factors that affect the classification ability, and are controlled by providing a flow blocking member.
The flow-inhibiting member may be any member that inhibits the flow of the processing liquid in the conveyance path 111. For example, a member in which a plurality of rod-like members are arranged at a position where the flow is to be controlled, a member in which a sponge-like member is arranged, a brush As long as it is an obstacle to the flow of the machining fluid, such as a member in which a shaped member is arranged. The separation fin 115 described above can be said to be an example of the flow blocking member. What kind of member is provided in what size and number may be appropriately set according to the flow to be controlled.

<Embodiment 2>
Next, by installing the classification / collection device according to the present invention in the cutting system, grinding can be performed without requiring a special cleaning device (centrifugation, paper filter, magnet separator, etc.). An explanation will be given of the machining fluid purification system.
In recent years, multi-axis and compounding of cutting machines have become mainstream, and the needs for grinding with cutting machines have increased. In this case, the machining fluid is common to both cutting and grinding, that is, both cutting waste and grinding waste (+ dropped abrasive grains) are stored in one working fluid tank. When cutting scraps and grinding scraps (the processing scraps generated by grinding are extremely small) are put into a large-capacity machining fluid tank, it becomes difficult to clean the machining fluid, and special cleaning is performed separately from the machining fluid tank. Devices (centrifugation, paper filter, magnet separator, etc.) need to be arranged in series.
On the other hand, during grinding, machining fluid containing machining waste is separately collected and passed through the classification / collection device according to the present invention, so that it can be easily cleaned without requiring a special cleaning device. Is.

FIG. 7 is an arrangement schematic diagram in the case of grinding with a lathe type 5-axis multi-tasking machine. In addition, the same code | symbol is used about the component similar to Embodiment 1. FIG.
When grinding is performed by attaching a grindstone 21 to a lathe type 5-axis multi-tasking machine, the working fluid collecting sheet 13 is spread at the lower part of the working area, thereby collecting the scattered working fluid and dropping it from one place. Allow to drain. An image of the flow of the machining liquid by the machining liquid collection sheet 13 is shown in FIG. The machining liquid collecting sheet 13 is stored at the time of cutting and can be expanded only at the time of grinding, so that mixing of grinding waste into the machining liquid tank 12 can be minimized.

<Embodiment 3>
In the third embodiment, the inclination angle can be adjusted in the installation of the classification / collection device 11 of the first and second embodiments.
By adjusting the inclination angle of the conveying path 111 of the classifying / collecting device 11, the flow rate of the working fluid flowing therethrough can be adjusted, and thereby the efficiency and accuracy of classification can be adjusted.
An inclination angle adjusting mechanism for adjusting the inclination angle of the conveyance path 111 of the classifying / collecting apparatus 11 is not particularly illustrated, but a known mechanism (for example, a hinge mechanism or a flexible tube) is appropriately selected and combined. And it can be realized.

Here, the flow rate of the machining fluid that changes based on the change in the gradient of apparatus installation and the supply flow rate will be examined.
FIG. 8 is a diagram showing an outline of the experimental apparatus under consideration. FIG. 9 is an explanatory diagram of Manning's official setting conditions.
The flow velocity V of the machining liquid is calculated from the set flow rate and the cross-sectional area of the actually flowing liquid.
V = Q / A Equation 3
Here, Q is the set flow rate, and A is the cross-sectional area of the flowing liquid. The water level (water height) actually flowing through the flow path was measured (see FIG. 8).
Further, when examining the flow velocity of the fluid flowing through the water channel, the Manning equation is generally used. Therefore, when the cross-sectional area is a trapezoid (see FIG. 9), the following Manning formula used for the calculation of the equal flow in the open channel is used.
A = (b + mH) H Equation 4
S = b + 2H (1 + m ² ) ^1/2 Equation 5
R = A / S Equation 6
V = (1 / n) · R ^2/3 · I ^1/2 Equation 7
Here, each symbol indicates the following.
Q: Flow rate V: Average flow velocity n: Roughness coefficient (value indicating the roughness of the channel wall surface and bottom surface, and varies depending on the material and state of the channel)
R: Depth (also known as hydraulic mean water depth. Divided product divided by Junbe)
S: Junbe (the length of water in contact with the surrounding wall and bottom in the cross section of the waterway) The length of the dotted line in FIG.
A: Cross-sectional area of flowing water in a water channel I: Hydrodynamic gradient hf / L (hf: energy loss, L: water channel extension)
In the case of uniform flow, since the hydrodynamic gradient = the water surface gradient = the water channel gradient, the water channel gradient is often used for the calculation.
FIG. 10 shows the experimental results for determining the relationship between the gradient of the flow path and the flow rate of the machining fluid with respect to the flow rate, and the calculation results based on the Manning equation (FIG. 10 (a): experimental results, FIG. 10 (b): calculation results based on the Manning equation). . As the roughness coefficient of the Manning equation, n = 0.02 was used.
It can be seen that the flow rate of the machining fluid flowing in the flow path can be changed by the gradient of the flow path.

As described above, since the inclination angle of the conveyance path 111 of the classification / collection device 11 can be adjusted, the flow rate of the working fluid flowing therethrough can be adjusted, thereby adjusting the classification ability, efficiency and accuracy. be able to.
In addition, the inclination angle of the conveyance path 111 is not limited to the same inclination throughout the entire conveyance path 111, and the inclination angle may be changed depending on the location. Thereby, for example, the inclination angle can be reduced as it goes from the upstream side to the downstream side, and the classification ability can be adjusted more closely.
In the conventional apparatus, when the collection and classification capabilities are to be changed, the apparatus itself needs to be replaced or extensively modified. However, according to the present embodiment, the classification / collection apparatus 11 is transported. This can be realized simply by adjusting the inclination angle of the path 111, which is very useful.
The adjustment of the tilt angle is not limited to the downward slope from the upstream to the downstream, but may be an upward slope from the upstream to the downstream.

The classifying / collecting apparatus according to the present invention can be installed in a space-saving manner with a simple configuration (can be installed on the flow path of the machining fluid). However, when the amount of machining fluid used is enormous, In order to secure the throughput capacity, a size corresponding to that is required.
Therefore, in the machining fluid supply method and apparatus disclosed in Japanese Patent No. 4523329 (in the machining fluid supply method using a floating nozzle, the outer layer of the machining fluid flow is more flexible than the machining fluid supply position in the tool rotation forward direction. By covering with a member, the working fluid flow is confined to the surface of the rotary tool, and by using the technology that discharges from the open end of the fluid introduction member before the processing point, the working fluid can be effectively used. Can be used as much as possible. Thereby, the classifying / collecting apparatus according to the present invention can be miniaturized as much as possible.
By combining the processing liquid supply method and apparatus disclosed in Japanese Patent No. 4523329 and the classifying / collecting apparatus according to the present invention, it is possible to obtain an extremely efficient and economical system in consideration of the environment.

  In each of the above embodiments, the case where the cross-sectional shape of the transport path 111 is constant has been described as an example, but the cross-sectional shape of the transport path 111 may be changed. For example, a configuration in which the transport path 111 becomes wider as it goes from the upstream side to the downstream side may be adopted. Also, this is combined with the adjustment of the inclination angle described above, for example, a configuration in which the inclination angle decreases as it goes from the upstream side to the downstream side, and the conveyance path 111 becomes wider as it goes from the upstream side to the downstream side (downstream) It is also possible to increase the ability to collect fine particles on the side while maintaining the processing capacity per hour).

  Further, a mechanism for dispersing the particles in the working fluid may be provided on the upstream side of the classifying / collecting device 11 in order to make the classification ability uniform. The mechanism may be anything that stirs the machining fluid containing particles, and may be agitated using power, or the power is used by forming a flow path that disturbs the flow of the machining fluid. It is also possible to stir without stirring.

11. . . Classification / collection device 111. . . Transport path 111h. . . Particle classification hole 112. . . Collection unit 113. . . Outlet 114. . . Magnetic particle recovery magnet 115. . . Separation fin (fin member)
117. . . Rectifying member 12. . . Processing fluid tank

Claims (9)

An apparatus for classifying and collecting particles contained in a liquid,
A transport path that forms a flow path for the liquid;
A plurality of particle classification holes formed in the downstream direction from the upstream of the conveying path;
A plurality of recovery portions for recovering the particles that have settled through the particle classification holes,
A classification / collection device characterized by comprising:   The classifying / collecting apparatus according to claim 1, wherein the conveyance path is inclined.   The classification / collection device according to claim 2, further comprising an inclination angle adjustment mechanism capable of adjusting the inclination angle.   The classification / collection device according to any one of claims 1 to 3, further comprising a discharge port at a lower portion of the collection unit.   The classification / recovery device according to claim 1, further comprising a magnet for collecting magnetic particles in the vicinity of the particle classification hole.   On the downstream side of the connection part of the particle classification hole and the recovery part, it protrudes to the upstream side substantially in parallel with the flow path direction of the transport path, and gradually decreases as the protrusion amount goes downward, and finally the recovery part. 6. The classifying / collecting device according to claim 1, wherein a rectifying member that is the same as the side wall is formed.   The classification / recovery device according to any one of claims 1 to 6, further comprising a fin member on a downstream side of a connection portion between the particle classification hole and the recovery portion.   The classification / recovery device according to claim 1, further comprising a flow inhibition member that inhibits the flow of the liquid in the conveyance path. The liquid is a working fluid used for grinding or cutting,
Classifying / collecting device according to any one of claims 1 to 8,
A working fluid tank provided downstream of the classifying / collecting device;
A microbubble generator for generating microbubbles in the processing liquid tank;
A machining fluid purification system comprising: