JP2009056553A - Device for removing magnetic foreign matters in wire saw slurry - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To effectively remove magnetic foreign matters contained in slurry with an attractor with a magnet and to effectively remove the magnetic foreign matters attracted to the attracting body for a repeated use of the attractor. <P>SOLUTION: The device for removing magnetic foreign matters in wire saw slurry comprises: a slurry receiving tank 11 for storing the slurry; the attractor 19 having a magnet movably inside the outer cover composed of non-magnetic material; a fluid driving means for moving the magnet inside the outer cover to an attaching position and a retracting position by the action of the fluid; a support device 15 which supports the attractor 19, inserts the attractor 19 with its magnet moved to the attracting position into the slurry in the slurry receiving tank 11 and takes out the attractor 19 from the slurry to outside after allowing the magnetic foreign matters in the slurry to be stuck on the outer surface of the outer cover; and a cleaning unit 13 which moves the magnet inside the attractor 19 taken out of the slurry to the retracting position to clean the attractor 19 under the condition that the attracting force of the magnetic foreign matters is lost, with the magnetic foreign matters removed. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a magnetic foreign matter removing apparatus for a wire source slurry that effectively removes magnetic foreign matter contained in a slurry after a silicon ingot is cut with a wire saw.

  When manufacturing thin plates such as an IC wafer and a solar cell wafer from a silicon single crystal or silicon polycrystal ingot, an apparatus called a wire saw is generally used. For example, a wire saw is a group of wires in which a single wire is wound at a predetermined pitch between a plurality of rollers, and the ingot is pressed against the wire while the wire is traveling at a high speed by the rotation of the roller. A wafer is manufactured by slicing a silicon ingot by supplying the cutting slurry to the contact portion between the ingot and the wire.

  In the slurry used in the wire saw, the abrasive grains are collected by a slurry processing apparatus, and the collected abrasive grains are adjusted to be mixed with a cutting fluid and then supplied to the wire saw again for circulation. Things have been done. Some cutting fluids are recovered and adjusted for reuse.

  FIG. 12 is a side view schematically showing an example of a conventional slurry processing apparatus. The slurry used in the wire saw 1 is stored in the waste liquid receiving tank 2, and the slurry in the waste liquid receiving tank 2 is first guided to the centrifuge 3. After being separated into abrasive grains and waste liquid, the waste liquid is stored in the waste liquid tank 4 and then sent to and stored in the waste liquid storage tank 5. The abrasive grains are stored in the regeneration tank 6 and then stored in the regeneration supply tank 7. Sent and stored. Then, the abrasive grains in the regeneration supply tank 7 are sent to the blending tank 8 and adjusted by mixing with new abrasive grains, new cutting fluid, etc., and then supplied again to the wire saw 1 and used for cutting the silicon ingot. . In the figure, 9 is a pump for feeding slurry.

  However, as described above, when the wire saw 1 is used to cut an ingot with a wire, there is a problem that particulate magnetic foreign matters such as iron are mixed in the slurry due to factors such as the wire being scraped at the same time. Further, the specific gravity of this kind of magnetic foreign matter is equal to the specific gravity of the abrasive grains, and the slurry has a relatively high viscosity, so that it is difficult to separate by the centrifugal separator 3 of the slurry processing apparatus. They are taken out together. For this reason, when the abrasive grains are circulated and used, there is a problem that the concentration of the magnetic foreign matter in the abrasive grains gradually increases.

  When the concentration of the magnetic fluid in the abrasive grains increases, magnetic foreign matter adheres to the wire of the wire saw and forms a dump, which not only impairs the cutting ability of the wire but also reduces the quality of the wafer to be cut. This causes a problem.

  For this reason, it is conceivable to separate the magnetic foreign matter by inserting a magnet into the slurry and attracting the magnetic foreign matter to the magnet by magnetic force. It is almost impossible to reliably remove the magnetic particles from the permanent magnets. Even when the electromagnet is used, the electromagnet has residual magnetism. Therefore, there is a problem that it is difficult to remove the magnetic foreign matter adsorbed on the magnet.

  For this reason, conventionally, when the concentration of the magnetic foreign matter is increased by circulating the abrasive grains, the abrasive grains or slurry are periodically taken out of the system and disposed of.

  On the other hand, Patent Document 1 discloses a magnetic foreign matter removing device that separates magnetic foreign matters so that the magnetic foreign matters are not directly attracted to a magnet. In Patent Document 1, a bar magnet is provided inside the cylindrical body, and the bar magnet can be moved in the cylindrical body by an entry / exit tool integrally attached to the bar magnet. Furthermore, the magnetic foreign substances adsorbed on the outer surface of the cylindrical body by the magnetic force of the bar magnet are configured to be removed by a scraper.

Further, in Patent Document 2, in a configuration in which a rod-shaped magnet made of a permanent magnet is disposed in a casing, in order to improve the magnetic foreign matter removal performance, a liquid material is swirled and guided in a casing like a cyclone. The thing which raised the contact probability is shown.
JP 2006-341212 A JP 2006-326447 A

  In the apparatus of Patent Document 1, in order to effectively separate magnetic foreign substances from the raw material (slurry), a plurality of cylinders into which bar magnets are inserted are provided, and each bar magnet is attached to the cylinders with an entry / exit tool. Must be moved at the same time. Here, the magnetic force of the bar magnet is inversely proportional to the square of the distance (Coulomb's law). Therefore, in order to increase the attractive force of the magnetic foreign matter by the bar magnet, the thickness of the cylinder is made as thin as possible and the inner surface of the cylinder And the outer surface of the bar magnet are desired to be as small as possible.

  However, if the distance between the cylinder and the bar magnet is set small, the distance between each bar magnet fixed to the entry / exit tool and the distance between the cylinders are accurate so that multiple bar magnets can be moved simultaneously by the entry / exit tool. There is a concern that even if there is a slight error, there is a concern that the bar magnet and the inner surface of the cylindrical body may rub against each other, and stable movement cannot be performed. Therefore, the device of Patent Document 1 is very difficult to manufacture. There is a problem.

  Further, in Patent Document 1, magnetic foreign substances adhering to the outer surface of the cylinder are scrubbed off with a scraper. However, this method cannot remove magnetic foreign substances on the outer surface of the cylinder in a good state. Alternatively, when abrasive grains or the like are included as in the wire source slurry, there is a problem that the cylindrical body is scraped by the scraper, and particles of the shavings of the cylindrical body are newly mixed into the slurry.

  On the other hand, Patent Document 2 does not have any means for removing the magnetic foreign matter adhering to the bar-shaped magnet. Therefore, the magnetic foreign matter adhering to the bar-shaped magnet cannot be removed. However, there is a problem that the magnetic foreign matter cannot be removed again.

  The present invention has been made in view of the above circumstances, and can effectively remove magnetic foreign substances contained in a slurry generated when a silicon ingot is cut with a wire saw by an adsorbent having a magnet. It is an object of the present invention to provide a wire foreign source magnetic foreign matter removing device that can effectively remove magnetic foreign matters adhering to the surface and repeatedly use an adsorbent.

The present invention is a wire foreign source magnetic foreign matter removing apparatus that repeatedly removes magnetic foreign matter contained in a slurry from a wire saw using a magnet,
A slurry receiving tank for storing the slurry;
An adsorbent body in which a magnet can be moved inside an outer casing made of a non-magnetic material;
Fluid driving means for moving a magnet in the outer shell to an adsorption position and a withdrawal position by the action of a fluid;
Insert the adsorbent that supports the adsorbent and the magnet has moved to the adsorbing position into the slurry in the slurry receiving tank, attach the magnetic foreign matter in the slurry to the outer surface of the outer casing, and then remove the adsorbent from the slurry. A supporting device,
A cleaning device that removes the magnetic foreign matter by moving the magnet in the adsorbent taken out of the slurry to the retreat position and cleaning the adsorbent in a state where the adhesion of the magnetic foreign matter is lost. The present invention relates to a magnetic foreign matter removing device.

  In the above-described wire foreign source magnetic foreign matter removing apparatus, the magnet may be a permanent magnet.

  Moreover, in the above-mentioned wire foreign material magnetic foreign matter removing apparatus, the magnet may be an electromagnet.

  Further, in the above-mentioned wire foreign material magnetic foreign matter removing apparatus, the outer cover may be made of a nonmagnetic metal.

  Further, in the magnetic foreign matter removing apparatus of the wire source library, the outer cover body may be made of resin.

  Moreover, in the magnetic foreign matter removing apparatus of the wire source library, the cleaning device may have a water injection device for injecting water onto the adsorbent.

  Moreover, in the magnetic foreign matter removing apparatus of the wire source library, the cleaning apparatus may have a brush-like scraping device in contact with the adsorbent.

  According to the magnetic foreign material removing apparatus for a wire source slurry of the present invention, an adsorbent body having a magnet inside a jacket made of a non-magnetic material is supported by a support device so that it can be inserted into and removed from a slurry receiving tank. Then, after inserting the adsorbent with the magnet moved to the adsorbing position by the fluid driving means into the slurry of the slurry receiving tank and attaching the magnetic foreign substance of the slurry to the outer surface of the outer cover, the adsorbent is taken out from the slurry, Since the magnet inside the adsorbent taken out of the slurry is moved to the retreat position and the adsorbent is washed with a cleaning device in a state where the adhesion of the magnetic extraneous matter has disappeared, the magnetic extraneous matter is removed. The adsorbent from which the adhering magnetic foreign matter is well removed by the cleaning device is inserted into the slurry receiving tank, and the magnetic foreign matter in the slurry can be effectively removed repeatedly by the adsorbent.

  Embodiments of the present invention will be described below with reference to the accompanying drawings.

  FIG. 1 is a side view showing an outline of a slurry processing apparatus provided with a magnetic foreign material removing apparatus for a wire source slurry according to the present invention. In a configuration similar to FIG. 12, waste liquid for storing slurry used for cutting an ingot with a wire saw 1 is stored. Between the receiving tank 2 and the centrifugal separator 3 that centrifuges the slurry into abrasive grains and waste liquid, a magnetic foreign matter removing device 10 that removes magnetic foreign matters such as iron in the slurry is provided.

  FIG. 2 is a front view of the magnetic foreign substance removing device 10, FIG. 3 is a view taken in the direction of arrows III-III in FIG. 2, and 11 is a slurry receiving tank provided on the table 12. The slurry from the waste liquid receiving tank 2 is introduced through a pump 9 and a receiving pipe 9a. Two cleaning tanks 13 a and 13 b constituting the cleaning device 13 are sequentially arranged at the rear part (right side in FIG. 3) of the slurry receiving tank 11.

  As shown in FIG. 2, a support device 15 that travels along the direction in which the slurry receiving tank 11 and the cleaning device 13 are arranged by the traverse rail 14 is provided on the left side of the slurry receiving tank 11 and the cleaning device 13. Yes.

  The support device 15 is provided with a lifting platform 17 that is moved up and down along the rail 16 by a combination of a servo motor and a ball screw, or a cylinder or other driving device. Is provided with a plurality of adsorbers 19 supported vertically. In the example shown in FIGS. 2 and 3, five adsorbers 19 arranged in the left-right direction are provided in two rows in the front-rear direction so as to be evenly arranged with respect to the inside of the slurry receiving tank 11.

  An inclined surface 20 is provided at the bottom of the slurry receiving tank 11, and the slurry is taken out from the lowermost portion of the inclined surface 20 by a pipe 21 and supplied to the centrifuge 3.

  As shown in FIG. 4, the adsorbing body 19 includes a cylindrical outer casing 22 made of a nonmagnetic material, and a magnet that is inserted in the outer casing 22 so as to move up and down with a slight gap. 23. The outer shell 22 made of a non-magnetic material is strong even when processed thinly, is hard to be cut by friction, and does not adversely affect the cutting of the ingot even if it is slightly cut and mixed in the slurry. Preferably, for example, SUS, aluminum, resin (PVC), or the like can be used. The magnet 23 can be a permanent magnet or an electromagnet. In the case of using an electromagnet, the power line connected to the magnet 23 can be moved up and down with the magnet 23 in the outer casing 22.

  FIG. 5 is a cross-sectional view showing an example of the fluid driving means in the adsorbing body 19. An inner cylinder 25 is inserted into the outer casing 22 with a slight gap 24. A magnet 23 is inserted inside, and a hole 26 is formed in the bottom of the inner cylinder 25. As shown in FIG. 4, a push-down valve 27 for supplying a fluid such as compressed air to the inside of the inner cylinder 25, the jacket 22 and the inner cylinder are provided at the upper end of the adsorbent body 19. And a push-up valve 28 for supplying a fluid to the gap 24 between the magnet 25 and the magnet 23 is pushed down to the suction position 29 when the fluid is supplied into the inner cylinder 25 by the push-down valve 27. When the fluid is supplied to the gap 24 between the outer casing 22 and the inner cylinder 25 by the push-up valve 28, the magnet 23 is pushed up by the fluid supplied from the lower portion through the gap 24 and the hole 26 and moves away. The fluid driving means is configured to be held at the position 30.

  FIG. 6 is a cross-sectional view showing another example of the fluid driving means. In this example, a fluid conduit 31 in which fluid is introduced from the lower end of the outer cover 22 into the lower end of the outer cover 22 into which the magnet 23 is inserted. In this embodiment, when the fluid is supplied to the upper end of the outer casing 22 by the push-down valve 27, the magnet 23 is pushed down and held at the suction position 29, and the fluid conduit 31 is pushed by the push-up valve 28. When the fluid is supplied, the magnet 23 is pushed up and moved to the retreat position 30 by supplying the fluid from the lower part of the outer casing 22.

  As shown in FIG. 7, when the adsorber 19 with the magnet 23 held at the adsorption position 29 is inserted into the slurry receiving tank 11 so that the adsorption position 29 is immersed in the slurry, the magnetic foreign matter 32 in the slurry becomes the magnet 23. It is attached to the outer surface of the outer shell 22 by the magnetic force.

  8 to 10 show an example of the cleaning device 13. The cleaning device 13 injects cleaning water into the cleaning tanks 13a and 13b and onto the adsorbent 19 inserted into the cleaning tanks 13a and 13b. A water jet device 33 is provided for cleaning and removing the magnetic foreign matter 32 (FIG. 7) adhering to the outer surface of the jacket 22. In the embodiment shown in FIG. 8, each of the adsorbents is provided from a plurality of nozzles 36 provided in a plurality of pipes 35 branched into three so as to sandwich the adsorbents 19 provided in two rows from both sides as described above. The cleaning water is sprayed to 19 for cleaning.

  Further, instead of providing the washing tanks 13a and 13b with the water injection device 33, a brush-like scraping device 37 as shown in FIG. 11 may be provided. The device 37 may be freely rotated or rotated by a driving device. Further, the water injection device 33 and the brush-like scraping device 37 may be provided together.

  The cleaning water in the cleaning tanks 13a and 13b is taken out through the pipes 38 and 39 and purified to remove the magnetic foreign matter 32 and the like, and then guided to the water injection device 33 again for circulation.

  2 illustrates the case where the two cleaning tanks 13a and 13b are provided and the cleaning is performed twice. However, the magnetic foreign matter 32 attached to the adsorbent body 19 can be satisfactorily cleaned and removed by one cleaning. In some cases, a single washing tank may be used.

  Next, the operation of the illustrated example will be described.

  The slurry used for cutting the ingot in the wire saw 1 of FIG. 1 and stored in the waste liquid receiving tank 2 is supplied to the slurry receiving tank 11 of the magnetic foreign matter removing apparatus 10 of FIG.

  Subsequently, as shown in FIG. 2, the lifting platform 17 provided in the support device 15 is lowered to immerse the plurality of adsorbers 19 supported by the support book 18 into the slurry of the slurry receiving tank 11. At this time, the pressing valve 27 shown in FIGS. 5 and 6 is operated to supply fluid such as compressed air to the upper side of the magnet 23, so that the magnet 23 is pushed down and held at the attracting position 29.

  Then, the magnetic foreign matter 32 in the slurry is attracted to the attracting body 19 inserted into the slurry by the magnetic force of the magnet 23, and the magnetic foreign matter 32 adheres to the outer surface of the outer cover 22.

  Subsequently, the lifting platform 17 provided in the support device 15 is raised, and the plurality of adsorbers 19 are pulled out from the slurry of the slurry receiving tank 11.

  Thereafter, the support device 15 is caused to travel along the traverse rail 14 in the right direction in FIG. 3 and stopped at the position of the cleaning tank 13a.

  Further, the push-up valve 28 is operated to supply a fluid such as compressed air to the gap shown in FIG. 5 or the fluid conduit 31 shown in FIG. As described above, when the magnet 23 moves to the retreat position 30, the adhesive force of the magnetic foreign matter 32 attached to the outer cover 22 is lost.

  Therefore, the adsorbing body 19 in this state is inserted into the cleaning tank 13a by lowering the lifting platform 17, and the cleaning water is injected from the nozzle 36 of the water injection device 33 shown in FIGS. When the body 19 is washed, the magnetic foreign matter 32 adhering to the outer surface of the jacket 22 is effectively washed away. At this time, cleaning may be performed using a brush-like scraping device 37 as shown in FIG. 11, and the water jet device 33 and the brush-like scraping device 37 may be cleaned together. As a result, the cleaning effect can be further enhanced.

  When the magnetic foreign matter 32 adhering to the adsorbing body 19 is not completely removed, the support device 15 is caused to travel again in the right direction in FIG. 3 along the traverse rail 14 and stopped at the position of the cleaning tank 13b. The adsorbent 19 is washed by this method. When the magnetic foreign matter 32 adhering to the adsorbent 19 can be satisfactorily removed by a single cleaning, the cleaning in only one cleaning tank 13a may be performed.

  The adsorbent 19 from which the magnetic foreign matter 32 has been satisfactorily removed by washing is removed by inserting it again into the slurry receiving tank 11 as shown in FIG. 2 and adsorbing the magnetic foreign matter 32 in the slurry in the same manner as described above. The removal operation of the magnetic foreign matter 32 by the adsorbent 19 is performed so that the concentration of the magnetic foreign matter 32 in the slurry of the slurry receiving tank 11 becomes a predetermined value or less. If the concentration of the magnetic foreign matter 32 in the slurry can be sufficiently reduced by one adsorption, the adsorption operation may be performed once. The slurry in the slurry receiving tank 11 in which the concentration of the magnetic foreign matter 32 is lowered by the adsorption is supplied to the centrifugal separator 3 (FIG. 1) of the slurry processing apparatus and separated into abrasive grains and waste liquid.

  In addition, the magnetic foreign matter removing apparatus for the wire source slurry of the present invention is not limited to the above-described embodiment, and it is needless to say that various changes can be made without departing from the gist of the present invention.

It is a side view which shows the outline of the slurry processing apparatus provided with the magnetic foreign material removal apparatus of the wire source slurry of this invention. It is a front view of the magnetic foreign material removal apparatus of FIG. It is a III-III direction arrow directional view of FIG. It is a side view of an adsorbent. It is sectional drawing which shows an example of the fluid drive means in an adsorption body. It is sectional drawing which shows the other example of a fluid drive means. It is sectional drawing which shows the state in which a magnetic foreign material adheres to the outer surface of a jacket body by the magnetic force of a magnet when an adsorption body is inserted in a slurry. It is a top view in case a washing | cleaning apparatus is a water injection apparatus. It is the IX-IX direction arrow directional view of FIG. It is sectional drawing which has wash | cleaned the magnetic foreign material adhering to the adsorption body with the washing water. It is a side view in case a washing | cleaning apparatus is a brush-shaped scraping apparatus. It is a side view which shows the outline of an example of the conventional slurry processing apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Wire saw 10 Magnetic foreign material removal apparatus 11 Slurry receiving tank 13 Cleaning apparatus 15 Support apparatus 19 Adsorption body 22 Cover body 23 Magnet 29 Adsorption position 30 Retraction position 32 Magnetic foreign substance 33 Water injection apparatus 37 Brush-like scraping apparatus

Claims (7)

A magnetic foreign matter removing device for a wire source slurry that repeatedly removes magnetic foreign matter contained in a slurry from a wire saw using a magnet,
A slurry receiving tank for storing the slurry;
An adsorbent body in which a magnet can be moved inside an outer casing made of a non-magnetic material;
Fluid driving means for moving a magnet in the outer shell to an adsorption position and a withdrawal position by the action of a fluid;
Insert the adsorbent that supports the adsorbent and the magnet has moved to the adsorbing position into the slurry in the slurry receiving tank, attach the magnetic foreign matter in the slurry to the outer surface of the outer casing, and then remove the adsorbent from the slurry. A supporting device,
A cleaning device that removes the magnetic foreign matter by moving the magnet in the adsorbent taken out of the slurry to the retreat position and cleaning the adsorbent in a state where the adhesion of the magnetic foreign matter is lost. Magnetic foreign matter removal device.   The magnetic foreign material removing apparatus for wire source according to claim 1, wherein the magnet is a permanent magnet.   The magnetic foreign matter removing apparatus according to claim 1, wherein the magnet is an electromagnet.   The apparatus for removing a magnetic foreign material from a wire source according to any one of claims 1 to 3, wherein the outer casing is made of a nonmagnetic metal.   The magnetic foreign material removing apparatus for a wire source library according to any one of claims 1 to 3, wherein the outer casing is a resin.   The apparatus for removing magnetic foreign matter from a wire source according to any one of claims 1 to 5, wherein the cleaning device includes a water injection device for injecting water onto the adsorbent.   The apparatus for removing magnetic foreign matter from a wire source according to any one of claims 1 to 5, wherein the cleaning device has a brush-like scraping device in contact with the adsorbent.

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