JPH11314047A - Coolant cleaning device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To remove impurities contained in a coolant stored in a coolant tank and clean the coolant. SOLUTION: A coolant from which impurities are removed as specified after passing through a first cleaning means 1 and a second cleaning means 2, is stored into the storage container 4a of a coolant tank 4 and a supernatant flows into the adjacent container 4b sectioned through a partition plate 5. In the cleaning container 4b, a third cleaning means 3 composed a magnet rotation plate 22 is arranged. The impurities of comparatively lower specific gravity which flow into the cleaning container 4b together with a coolant are adsorbed into the surface of the magnet rotation plate 22, and are removed. Further, the impurities such as oils suspended in the liquid level of the coolant is caused to stick to the rotation plate 22 through adsorbed impurities and removed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a coolant purifying apparatus for removing impurities mixed in a coolant used in a machine tool and keeping the coolant clean.

[0002]

2. Description of the Related Art In general, impurities such as chips, abrasive grains, and oil are mixed into a coolant used in a machine tool.
When reused, the coolant needs to be purified once. As typical means for purifying the coolant, there are a magnet separator method, a filtration method, and a precipitation method.

(1) Magnet separator method Chips mainly composed of a magnetic substance mixed in a coolant,
Impurities such as abrasive grains are attracted to the magnet roller and separated from the coolant, and the impurities adsorbed to the magnet roller are removed by a scraper and removed.
For example, it is disclosed in JP-A-58-174211.

(2) Filtration method A method of filtering impurities mixed in a coolant using a filter material (a paper filter, a cloth filter, a metal filter, or a porous member such as a ceramic). No. 6,086,045.

(3) Precipitation method A relatively large impurity is precipitated and separated by utilizing a difference in specific gravity with a coolant. For example, Japanese Patent Application Laid-Open No. 58-84092
In the publication, a labyrinth is formed via a partition plate in a tank for collecting the coolant used in the machine tool, and impurities are removed when the coolant flows while being alternately changed in the vertical direction in the flow path at each partition plate. Precipitation techniques are disclosed. In general, this precipitation method is often used as a pre-process for reducing the load on each of the above-mentioned purification means. For example, in Japanese Patent Application Laid-Open No. 3-213269 described above, this method is used for a machine tool. The coolant is first guided to the first tank, where large impurities mixed in the coolant are precipitated. Subsequently, the coolant overflowing from the first tank is guided to a filtration section where a paper filter is laid. The coolant is filtered to remove small impurities.

(4) Floating method Fine particles or oil and other impurities mixed in the coolant are suspended and removed by a schema or the like. For example, Japanese Unexamined Patent Publication (Kokai) No. 59-39309 discloses that the coolant is recovered. An ultrasonic oscillation plate is disposed on the side wall of the tank to be heated, and the ultrasonic wave oscillated from the ultrasonic oscillation plate vibrates the oil-based impurities mainly turbid in the coolant to cause them to coagulate and float together. There is disclosed a technique for removing impurities by a schema. Also, Japanese Patent Laid-Open No. 4-12
No. 9643 discloses that the lower side of a rotary plate having a plurality of grooves spirally or concentrically on the surface is immersed vertically in a coolant stored in a coolant tank and slowly rotated to reduce the liquid level of the coolant. A technology has been disclosed in which impurities mainly composed of floating oil are attached to the surface of the rotating plate to separate them from the coolant, and then the impurities attached to the surface of the rotating plate are wiped off with a scraper and accumulated in a predetermined manner. .

It is to be noted that the magnet roller is separated from the magnet roller,
Alternatively, the impurities deposited in the coolant tank are described in Japanese Patent Application Laid-Open No. 58-174211, or
As disclosed in Japanese Patent No. 13269 or the like, discharge is often performed by a chip conveyor disposed at the bottom of the tank.

[0008]

However, even if any of the conventional purification methods is adopted or a combination thereof, it is not possible to completely remove various impurities mixed in the coolant. . For example, if a magnet separator is used, it is possible to remove about 80 to 90% of impurities such as chips and abrasive grains mainly composed of a magnetic substance mixed in a coolant. Cannot be completely removed. Also, when a magnet separator and a filter medium such as a paper filter are used in combination, it is possible to remove to a certain extent the impurities that could not be removed by the magnet separator with the filter medium. However, if a filter medium with a fine mesh is used, clogging is likely to occur, so that the frequency of replacing the filter medium increases and the workability is poor.

Further, in the precipitation method, the coolant is separated by utilizing the difference in specific gravity between the coolant and impurities mixed in the coolant. Therefore, the coolant must be kept for a long time to completely separate the coolant. This requires a large-volume tank and a large amount of coolant, which increases equipment costs.

[0010] As a result, the impurities collected by the respective purifying means easily accumulate in the coolant tank for collecting the coolant used in the machine tool, and the accumulated impurities serve as a catalyst for bacterial growth to accelerate the deterioration of the coolant. As a result, the generation of an unpleasant odor is expedited, and the amount of waste liquid is increased, leading to a rise in running costs.

If the coolant from which the impurities have not been completely removed is sucked by the coolant pump, the impurities mixed in the coolant may damage the inside of the coolant pump and cause deterioration of the strength. The durability is reduced. Further, when the coolant from which the impurities are not completely removed is supplied to the cutting point or the grinding point of the machine tool, not only the cutting conditions are lowered, but also the life of the tool or the grindstone to be used is shortened.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and has as its object to provide a coolant purifying apparatus capable of completely removing impurities mixed in a coolant and keeping the coolant always clean. I do.

[0013]

According to a first aspect of the present invention, there is provided a coolant purifying apparatus for purifying impurities contained in a coolant used in a machine tool and storing the impurities in a coolant tank. The above-mentioned coolant tank is provided with a purifying means having a magnet rotating plate which is immersed on the lower side of the coolant liquid stored in the coolant tank and rotates to adsorb impurities floating in and on the coolant liquid on the surface. It is characterized by having been established.

A coolant purifying apparatus according to a second aspect of the present invention is the coolant purifying apparatus according to the first aspect, wherein the purifying means includes a scraper for wiping a surface of the magnet rotating plate exposed from a liquid level of the coolant. It is characterized by.

[0015] A coolant purifying apparatus according to a third aspect of the present invention is the coolant purifying apparatus according to the first or second aspect.
The magnet rotating plate is formed of a central plate on which a plurality of magnets are arranged on a circumference and a thin plate made of a non-magnetic material covering both surfaces of the central plate.

A coolant purifying apparatus according to a fourth aspect of the present invention is the coolant purifying apparatus according to the first or second aspect,
The magnet rotating plate is characterized by being formed of a magnetized center plate and a thin plate made of a non-magnetic material covering both surfaces of the center plate.

The coolant purifying apparatus according to the fifth invention is the coolant purifying apparatus according to the third or fourth invention, wherein:
The center plate is made of a non-magnetic material.

A coolant purifying apparatus according to a sixth aspect of the present invention is the coolant purifying apparatus according to any one of the third to fifth aspects, wherein the non-magnetic material is a resin material.

That is, in the coolant purifying apparatus according to the first invention, impurities floating in the coolant stored in the coolant tank and on the coolant level are immersed in the lower side of the coolant level and rotated by the magnet rotating plate. It is absorbed and removed by the surface of the magnet rotating plate.

In the coolant purifying apparatus according to the second invention,
In the coolant purifying apparatus according to the first invention, the surface of the magnet rotating plate exposed from the coolant level is wiped with a scraper, so that the magnet rotating plate is removed from the coolant level after impurities attached to the surface are removed. Since it is immersed, impurities can be efficiently attached to the surface of the magnet rotating plate.

In the coolant purifying apparatus according to the third invention,
In the coolant purifying apparatus according to the first or second aspect of the present invention, the magnet rotating plate has a three-layer structure including a central plate on which a plurality of magnets are arranged on a circumference, and a thin plate made of a non-magnetic material covering both surfaces of the central plate. By doing so, impurities attached to the surface of the magnet rotating plate can be wiped without damaging the magnet.

In the coolant purifying apparatus according to the fourth invention,
In the coolant purifying apparatus according to the first or second aspect of the present invention, the magnet rotating plate includes a magnetized center plate,
By adopting a three-layer structure including a thin plate made of a nonmagnetic material that covers both surfaces of the center plate, impurities mixed in the coolant can be attached to the entire magnet rotating plate.

In this case, preferably, the center plate is made of a non-magnetic material as in the coolant purifying apparatus according to the fifth invention.

Further, preferably, the non-magnetic material is a resin material as in the coolant purifying apparatus according to the sixth invention.

[0025]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. 1 to 13 show a first embodiment of the present invention. As shown in FIGS. 2 and 3, the coolant purifying device A in the present embodiment is disposed on a back surface R of a machine tool B that performs cutting, grinding, or the like. This coolant purifying device A purifies, collects and recirculates the coolant used in the machine tool B, and as shown in FIG. 4, a first purifying means for purifying the coolant used in the machine tool B. 1, a second purifying means 2, a third purifying means, a coolant tank 4 for collecting coolant, and the like. The coolant tank 4 is provided with an upstream storage tank 4a and a downstream clean tank via a partition plate 5. 4b.

A coolant pump 6 faces the cleaning tank 4b via a strainer 7.
The coolant staying in the space is sucked by the coolant pump 6 and supplied to a cutting point (or a grinding point) between the tool (not shown) of the machine tool B and the workpiece W via the supply pipe 8.

[0027] As shown in FIG.
Is mainly composed of a known so-called magnet separator, and a main body 10 is provided with a pocket 11 used for the machine tool B and for receiving the coolant flowing out of the drain passage 9.
A magnet roller 12 for adsorbing chips, abrasives, and the like mixed in the coolant overflowing from 1 is provided, and the magnet roller 12 is connected to a motor (not shown).

An outlet 13 is provided on the downstream side of the pocket 11 with the magnet roller 12 therebetween.
Further, a dewatering roller 14 for squeezing water mixed in the chips, abrasive grains and the like adsorbed on the magnet roller 12 is pressed against the magnet roller 12, and a scraper 15 is slidably contacted with the magnet roller 12. A sludge box 16 is provided at a lower end.

The outlet 13 of the first purifying means 1 extends to the second purifying means 2. The second purifying means 2 is provided with a tray 17, and the tray 17 is disposed on the liquid surface of the storage tank 4a. As shown in FIG. 7, the peripheral surface and the bottom surface of the tray 17 are formed by a mesh plate 17b such as an expanded metal or a punched metal, and a filter medium 18 such as a paper filter is mounted on the inner surface thereof. Further, a settling portion 19 and a magnet plate 20 are provided on the tray 17.

As shown in FIG. 8 and FIG.
Is formed in a relatively shallow box shape, and is placed with a gentle inclination with respect to the tray 17. A cushioning material 19a such as sponge or felt is loaded on the bottom of the sedimentation portion 19, and an expanded metal 19b is mounted thereon. The outlet 13 of the first purifying means 1 faces upstream of the sedimentation section 19.
The magnet plate 20 is continuously provided with a predetermined step at the downstream end. The magnet plate 20 is installed so as to be gently inclined from the upstream end to the downstream end connected to the sedimentation section 19. A plurality of magnets 21 are embedded in this magnet plate 20,
The surface of the magnet 21 is the magnet plate 2
The surface is exposed almost on the same plane as the surface of No. 0.

The cleaning tank 4b of the coolant tank 4
Is provided with a third purification means 3. The third purifying means 3 is provided with a magnet rotating plate 22, and the magnet rotating plate 22 is arranged at a predetermined interval in parallel with the partition plate 5 that partitions the coolant tank 4. An opening 5a is cut out at the center of the upper end of the partition plate 5, and a rotating shaft 23 which is pivotally mounted on the center of rotation of the magnet rotating plate 22 has a bearing slightly above the center of the opening 5a. And the lower side of the magnet rotating plate 22 is immersed in the coolant staying in the cleaning tank 4b. Therefore, the magnet rotating plate 22 is disposed with one side face facing the opening 5a.

As shown in FIGS. 11 and 12, the magnet rotating plate 22 is made of a central plate 22a formed of a non-magnetic material such as resin, and a non-magnetic material such as resin which covers both surfaces thereof. And a plurality of magnets 24 are embedded at substantially equal intervals on the circumference of the central plate 22a.
A pulley 25a is mounted on the rotary shaft 23. The pulley 25a is connected to a pulley 25b mounted on a main shaft of a motor 26 via a belt 25c.

The magnet rotating plate 22 rotates clockwise toward the paper surface of FIG. 6, and a scraper 27 for wiping the surface of the magnet rotating plate 22 is provided before the magnet rotating plate 22 is immersed in the coolant. At the lower end of the scraper 27, a fine powder accumulation box 28 is provided. As shown in FIG. 13, this fine powder accumulation box 28
A mesh plate 29 having a small hole is formed on the bottom surface of the filter, and a filter 30 is mounted thereon.

Next, the operation of the embodiment having the above configuration will be described. The coolant stored in the cleaning tank 4b of the coolant tank 4 is sucked by the coolant pump 6 via the strainer 7, and supplied to the cutting point (or grinding point) of the machine tool B via the supply pipe 8. Then, the coolant used in the machine tool B passes through the drain passage 9 and passes through the pocket 11 provided in the main body 10 of the first purifying means 1.
Flows to

Then, the coolant overflowing from the pocket 11 passes through the magnet roller 12 rotated by a motor (not shown) and is discharged from the discharge port 13. The coolant is the magnet roller 1
When passing through 2, relatively large particles mainly composed of magnetic material such as cutting chips and abrasive particles mixed in this coolant are adsorbed, and at the same time, some particles mainly composed of non-magnetic material are Attached via the particles already adsorbed.
The powder particles adsorbed and adhered to the magnet roller 12 are dewatered by the dewatering roller 14 and then peeled off by the scraper 15 to be accumulated in the sludge box 16. As a result, the first purifying means 1 removes 80% of impurities mainly composed of magnetic substances mixed in the coolant.
~ 90% are removed.

The outlet 13 of the first purifying means 1
When the coolant discharged from is dropped on the sedimentation part 19 provided in the second purification means 2, it flows down along the inclination of the sedimentation part 19. In this sedimentation section 19, expanded metal 1
9b, the coolant is diffused in the width direction along the grid of the expanded metal 19b, and at the same time, impurities having a relatively high specific gravity, such as grinding stone powder, remaining in the coolant are precipitated. It is deposited on the steps formed by the grid.

The coolant diffused in the sedimentation section 19 flows down on the entire surface of the sedimentation section 19 at a substantially constant speed and falls on the magnet plate 20. Then, when the coolant flows down the surface of the magnet plate 20, fine magnetic powder particles such as cutting chips remaining in the coolant are adsorbed on the surface of the magnet 21 embedded in the magnet plate 20, At the same time, other impurities are attached to some extent via the powder particles adsorbed by the magnet 21.

Thereafter, the coolant flowing down the magnet plate 20 is dropped on the tray 17. A filter medium 18 is laid on the tray 17, and most of the impurities that cannot be completely removed in the above-described series of purification steps are removed by the filter medium 18. In addition, the coarseness of the filter medium 18 is as follows.
An appropriate one is selected according to the flow rate of the coolant and the amount of impurities mixed at the time of cutting or grinding such as chips and abrasive grains.

The sedimentation section 19 and the magnet plate 20 can be removed. When the amount of deposited or adhering impurities reaches a predetermined amount, the sedimentation section 19 and the magnet plate 20 can be removed and cleaned. Exchange. Similarly, the filter medium 18 is appropriately replaced when a predetermined amount of impurities is deposited.

The coolant that has been filtered by the filter medium 18 is dropped and stored in the storage tank 4 a of the coolant tank 4. The first purifying means 1 and the second purifying means 2
Almost all impurities remaining in the coolant were removed by the above process, so that only a small amount of fine impurities having a low specific gravity remained in the coolant staying in the storage tank 4a. Therefore, the impurities were deposited in the storage tank 4a. Instead, the growth of bacteria is prevented, so that the decay of the coolant is prevented, the odor is not generated, and the coolant can be used for a long period of time simply by replenishing the spent coolant occasionally.

Then, of the coolant retained in the storage tank 4a, the coolant overflowing from the opening 5a of the partition plate 5 flows into the adjacent cleaning tank 4b. In this cleaning tank 4b, the magnet rotating plate 22 provided in the third purification means 3 is slowly rotated by the motor 26. A plurality of magnets 24 are mounted on the center plate 22a of the magnet rotating plate 22, and when the magnet rotating plate 22 is sequentially immersed in the coolant and moves, fine impurities floating in the coolant are removed. The magnetic force of the magnet 24 attracts the surface, and at the same time, impurities having a relatively low specific gravity such as oil floating on the liquid surface of the coolant adhere to the surface of the magnet rotating plate 22.

The impurities captured by the magnet rotating plate 22 are separated from the coolant by exposing the magnet rotating plate 22 from the liquid level of the coolant, and the scraper is removed before the magnet rotating plate 22 re-enters the coolant. It is wiped off at 27 and is accumulated in the fine powder accumulation box 28. A filter 30 is mounted on the bottom of the fine-powder accumulation box 28, and the bottom of the fine-powder accumulation box 28 is formed by a mesh plate 29 having a small hole. The coolant that has flowed in along with the coolant is dropped into the coolant tank 4 through the filter 30 and the mesh plate 29.

The amount of impurities remaining in the coolant flowing from the storage tank 4a to the cleaning tank 4b is extremely small, and the amount of impurities trapped by the magnet rotating plate 22 is a small amount of oil. Therefore, the impurities stay in the cleaning tank 4b. The coolant is always clean without rot odor,
It can be used for a long time. As a result, not only can the running cost required for coolant replacement, etc. be reduced,
Deterioration of the strength of the coolant pump 6 is prevented and durability is improved. Further, since a clean coolant can be supplied to the cutting point or the grinding point of the machine tool B, the life of the tool or the grindstone used becomes longer, and the cutting conditions in the cutting work are improved.

The center plate 22a of the magnet rotating plate 22 of the third purifying means 3 is
a itself may be a magnetized plate. Further, the magnet rotating plate 22 may be provided on the storage tank 4a side.

By the way, the flow rate of the coolant used in the machine tool B or the discharge amount of the chips, abrasive grains and the like generated by the machine tool B is relatively large, and fine chips and the like are stored in the storage tank 4a. In the case where impurities are likely to remain, a magnet conveyor 31 having a loop-shaped magnet sheet 31a is disposed at the bottom of the storage tank 4a below the second purification means 2, as shown in FIGS. , The storage tank 4
Impurities such as fine chips that float in a may be adsorbed to the magnet sheet 31a. When a predetermined amount of impurities are adsorbed on the magnet sheet 31a, or at predetermined time intervals, the magnet conveyor 31 is rotated manually or via a motor to remove the impurities adsorbed on the magnet sheet 31a from the coolant tank 4. And the impurities adsorbed on the magnet sheet 31a are separated by a scraper 32 slidingly in contact with the magnet sheet 31a and accumulated in an accumulation box.

It is convenient to arrange the magnet bar 34 as an accessory for cleaning as shown in FIG. A magnet (built-in part in the figure) 34a of the magnet bar 34 has a built-in magnet, or the tip 34a itself is magnetized and the handle 4
The inside of the coolant tank 4 is agitated by grasping 3b to adsorb impurities such as minute chips floating in the coolant. A flange 34c is removably attached to the tip 34a, and impurities attached to the tip 34a are removed by relatively sliding the collar 34c.

Further, as shown in FIG.
In the sedimentation section 19 provided in the above, instead of the cushioning material 19a and the expanded metal 19b, the lattice groove 1 as a step is provided.
A sedimentation portion 19c having 9d vertically and horizontally may be attached. In this case, the coolant flowing down the settling portion 19c is diffused along the lattice grooves 19d, and the coolant is diffused along the lattice grooves 19d.
An impurity precipitates in d. Then, when the amount of impurities deposited in the lattice groove 19d reaches a predetermined amount, it is removed and cleaned or replaced with a new one. The lattice grooves 19d of the settling portion 19c are formed in a zigzag pattern in the flow direction of the coolant indicated by the arrow as shown in FIG. 18A, or as shown in FIG. Various modes are conceivable, such as forming in such a square shape. Further, the sedimentation section 1
The same effect can be obtained by forming a stepped portion 19e having a sawtooth cross section as shown in FIG.

[0048]

As described above, according to the present invention, the following effects can be obtained. According to the first aspect of the present invention, since the purifying means having the magnet rotating plate which is immersed on the lower side of the coolant level and rotates is disposed in the coolant tank for storing the coolant, the coolant is provided in the coolant level and in the coolant level. Impurities mainly composed of floating magnetic material are adsorbed on the surface of the magnet rotating plate, and relatively light specific impurities such as oil are attached via the adsorbed impurities, so the coolant stored in the coolant tank Can be cleaned.

In this case, the surface of the magnet rotating plate exposed from the coolant level is wiped off with a scraper to remove impurities adhering to the surface. Since the surface is immersed in the coolant, impurities can be efficiently adsorbed.

According to the third aspect of the present invention, the magnet rotating plate comprises a central plate having a plurality of magnets arranged on the circumference thereof, and a three-layer coating of a thin plate made of a non-magnetic material on both sides of the central plate. By adopting the structure, in addition to the effects of the invention described in claim 1 or 2, the impurities attached to the surface of the magnet rotating plate can be easily wiped without damaging the magnet, and the durability is improved.

According to the fourth aspect of the present invention, the magnet rotating plate has a three-layer structure in which a magnetized central plate and a thin plate made of a non-magnetic material are coated on both surfaces of the central plate. Alternatively, in addition to the effect of the invention described in 2, the impurities mixed in the coolant can be adsorbed by the entire magnet rotating plate, and the impurities can be efficiently removed from the coolant.

According to the fifth aspect of the present invention, in addition to the effects of the third or fourth aspect of the present invention, impurities can be intensively attached to the magnet by using a non-magnetic material for the center plate.

According to the sixth aspect of the invention, by using a non-magnetic material as a resin material, in addition to the effects of the third to fifth aspects, processing is facilitated and the weight of the magnet rotary plate is reduced. Can be realized.

[Brief description of the drawings]

FIG. 1 is a perspective view of a first purifying unit, a second purifying unit, and a coolant tank.

FIG. 2 is a rear view showing an arrangement of a machine tool and a coolant purifying device.

FIG. 3 is a right side view of FIG. 2;

FIG. 4 is a schematic diagram of a coolant purifying device.

FIG. 5 is a plan view of a coolant tank, a second purification device, and a third purification device.

6 is a sectional view taken along the line VI-VI in FIG.

FIG. 7 is a perspective view of a tray provided in the second cleaning means.

FIG. 8 is a side cross-sectional view of a sedimentation section provided in the second purification means.

FIG. 9 is a perspective view of a settling unit provided in the second purification unit.

FIG. 10 is a perspective view of a magnet plate provided in a second purification unit.

FIG. 11 is a front view of a rotating plate provided in a third purification unit.

FIG. 12 is a sectional view taken along the line XII-XII of FIG.

FIG. 13 is an enlarged sectional view of a main part of a rotary plate provided in a third purifying means.

FIG. 14 is a partially enlarged cross-sectional view showing a mode in which a magnet conveyor is disposed below a second purifying unit.

FIG. 15 is a perspective view of a magnet conveyor.

FIG. 16 is a perspective view of a magnet bar.

FIG. 17 is a side cross-sectional view of a settling unit according to another embodiment.

FIG. 18 is an enlarged view of a part of FIG.

FIG. 19 is a side cross-sectional view of a settling section according to another embodiment.

[Explanation of symbols]

 A Coolant purification device 4 Coolant tank 15 Scraper 22 Magnet rotating plate 22a Central plate 22b Thin plate 24 Magnet

Claims (6)

[Claims] 1. A coolant purifying apparatus for purifying impurities contained in a coolant used in a machine tool and storing the impurities in a coolant tank, wherein the coolant tank is provided with a lower surface of a coolant liquid stored in the coolant tank. A cleaning device which has a magnet rotating plate for immersing and rotating the substrate and adsorbing impurities floating in the coolant and on the surface of the coolant on the surface thereof. 2. A coolant purifying apparatus according to claim 1, wherein said purifying means includes a scraper for wiping a surface of said magnet rotating plate exposed from a liquid level of said coolant. 3. The magnet rotating plate according to claim 1, wherein the magnet rotating plate is formed of a central plate on which a plurality of magnets are arranged on a circumference and a thin plate made of a non-magnetic material covering both surfaces of the central plate. The coolant purifying device according to claim 1 or 2. 4. The coolant according to claim 1, wherein the magnet rotating plate is formed by a magnetized center plate and a thin plate made of a non-magnetic material covering both surfaces of the center plate. Purification device. 5. The coolant purifying apparatus according to claim 3, wherein said center plate is made of a non-magnetic material. 6. The coolant purifying apparatus according to claim 3, wherein said non-magnetic material is a resin material.