JP2012125891A - Slurry control device for wire saw - Google Patents

Abstract

PROBLEM TO BE SOLVED: To facilitate adjustment of slurry supplied to a fixed abrasive grain wire saw and to enable stable cutting.SOLUTION: This slurry control device for the wire saw includes: a first tank 5A receiving slurry waste 3; a centrifugal separator 14 to which the slurry waste 3b in the first tank 5A is introduced to separate slurry 2; a second tank 5B receiving the slurry 2 in the centrifugal separator 14; a slurry supply route 26 supplying the slurry 2 in the second tank 5B to the fixed abrasive grain wire saw 1; a controller 41 detecting a slurry concentration from detection values by a gravimeter 29 and a viscometer 30 provided in a circulation flow passage 28 taking out and circulating the slurry 2 in the second tank 5B; a slurry discharge route 33 discharging part of the slurry 2 in the second tank 5B as waste slurry 31; and a new slurry supply route 38 supplying new slurry 2a to the second tank 5B. The waste slurry 31 is discharged in the slurry discharge route 33 and the new slurry 2a is supplied in the new slurry supply route 38, so that the slurry concentration detected by the controller 41 maintains a specified concentration.

Description

  The present invention relates to a slurry management device for a wire saw in which a slurry supplied to a fixed abrasive wire saw can be easily adjusted and stable cutting can be achieved.

  Conventionally, a wire saw has been used as an apparatus for forming a wafer by cutting a workpiece to be cut (for example, a silicon ingot). In this wire saw, a thin wire row to which tension is applied is run, and the object to be cut is made into a wire row while spraying abrasive containing abrasive grains for cutting on the coolant to remove cutting heat. There is a free abrasive wire saw in which an object to be cut is simultaneously cut into a plurality of wafers by pressing (see, for example, Patent Document 1).

  Further, in recent years, by using a fixed abrasive wire array in which diamond abrasive grains or the like are previously attached to the surface of a thin wire, the object to be cut is pressed against the wire array while spraying slurry as coolant on the wire array. There is a fixed abrasive wire saw that cuts an object to be cut into a plurality of wafers simultaneously (see, for example, Patent Document 2).

  In the loose abrasive wire saw and the fixed abrasive wire saw, in order to form a large number of wafers by cutting a silicon ingot, it is common to perform a single batch operation from the start to the end of the cutting operation. is there. In addition, slurry management by separating and recovering the slurry waste liquid from the wire saw by separating and recovering it is being studied for effective use of resources and volume reduction of waste.

  In the loose abrasive wire saw, the slurry in which the abrasive is mixed with the coolant is supplied to the wire to cut the silicon ingot. Therefore, the slurry waste liquid discharged from the loose abrasive wire saw is the abrasive (SiC) in the coolant. And chips (Si) are mixed. Therefore, in order to separate and recover such slurry waste liquid, the slurry waste liquid is separated into a coolant and a solid content, and the solid content is separated in two stages of abrasive grains = recovery and chips = discard. Here, when continuous separation is attempted, the slurry waste liquid is continuously withdrawn, and while monitoring the amount to be withdrawn and the amount to be collected for each, the collection of abrasive grains, the disposal of chips, the preparation of new coolant and new abrasive grains There is a problem that it is difficult to manage because it is necessary to perform complicated operations such as returning the regenerated slurry. For this reason, the batch type is generally used for slurry management of slurry waste liquid from loose abrasive wire saws.

  In the above-mentioned fixed abrasive wire saw, the slurry consisting only of coolant is supplied to the fixed abrasive wire to cut the silicon ingot. Therefore, the slurry waste liquid discharged from the fixed abrasive wire saw is cut into the coolant. Silicon particles are mixed.

Japanese Patent Laid-Open No. 11-309664 JP 2010-29998 A

  It is known that the fixed abrasive wire saw can greatly increase the cutting speed as compared to the loose abrasive wire saw. Since the cutting speed is high, the quality of the slurry (that is, the specific gravity of the solid content in the slurry). If the slurry concentration (representing the cutting property in consideration of the particle size obtained from the viscosity of the solid content) is not accurately controlled with respect to the concentration obtained from the above, the cutting quality is not stable. In batch type slurry management, the slurry concentration at the start of cutting and at the end of cutting greatly changes the cutting quality, so it is difficult to adopt the batch type for managing the slurry waste liquid of fixed abrasive wire saws. is there. In addition, in order to supply a slurry of stable quality to a fixed abrasive wire saw using a batch system, it is necessary to store a large amount of slurry, and there is a problem that equipment and cost increase.

  For this reason, it is desirable to manage the slurry waste liquid of fixed abrasive wire saws by continuously separating and reusing the slurry waste liquid cut with a small amount of slurry, but conventionally, solid particles have been easily stabilized from the slurry waste liquid. However, there is no disclosure of the management of the slurry that enables the slurry adjusted to the slurry concentration suitable for cutting to be stably supplied to the fixed abrasive wire saw.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a wire saw slurry management apparatus that can easily adjust the slurry supplied to a fixed abrasive wire saw and that can achieve stable cutting. It is in.

  In order to achieve the above object, a wire saw slurry management apparatus according to the present invention receives a slurry waste liquid from a fixed abrasive wire saw and stores the first tank, and introduces the slurry waste liquid of the first tank to obtain solid particles. A centrifuge to separate, a second tank for receiving and storing a slurry from which solid particles have been separated by the centrifuge, a slurry supply path for supplying the slurry of the second tank to the fixed abrasive wire saw, The specific gravity of the solid content in the slurry is obtained by taking in the specific gravity meter and the viscometer provided in the circulation flow path for taking out and circulating the slurry of the second tank, the specific gravity detection value by the specific gravity meter and the viscosity detection value by the viscometer. A controller for detecting the slurry concentration in consideration of the particle size obtained from the viscosity of the solid content with respect to the concentration obtained from the slurry, a slurry discharge system for discharging a part of the slurry of the second tank as waste slurry, and a new slurry Is supplied to the second tank A new slurry supply system, and the controller discharges the waste slurry by the slurry discharge system and the new slurry by the new slurry supply system so that the detected slurry concentration maintains a specified concentration. It is characterized by the fact that the supply is performed.

  In the wire saw slurry management apparatus, the first tank is provided with a cyclo separator, and the slurry waste liquid from the fixed abrasive wire saw is guided to the cyclone separator to increase the concentration of solid particles in the centrifuge. It is preferable to supply.

  In the wire saw slurry management apparatus, it is preferable that the specified concentration is a maximum concentration at which stable cutting with a fixed abrasive wire saw is possible.

  In the wire saw slurry management apparatus, it is preferable that the first tank and the second tank are integrally configured so that the slurry waste liquid in the first tank is supplied to the second tank through the overflow wall. .

  According to the slurry management device for a wire saw of the present invention, the slurry obtained by separating the solid particles by introducing the slurry waste liquid received in the first tank to the centrifuge is supplied to the second tank, The slurry is supplied to the fixed abrasive wire saw, and the slurry concentration in consideration of the viscosity indicating the particle size of the solid content with respect to the specific gravity indicating the solid content concentration of the slurry in the second tank is set to the specified concentration. Since a part of the slurry in the two tanks is discharged as waste slurry and the new slurry is supplied to the second tank, the first tank, the second tank, and the centrifuge having a relatively small volume are used to remove the slurry from the slurry waste liquid. An excellent effect that a slurry having a specified concentration can be generated and a stable cutting can always be secured by supplying the slurry having a specified concentration to the fixed abrasive wire saw can be obtained.

It is a block diagram which shows one Example of the slurry management apparatus of the wire saw in this invention. It is the diagram which compared and showed the management of the slurry by this invention, and the management at the time of batch-processing the slurry waste liquid conventionally.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a block diagram showing an embodiment of a wire saw slurry management apparatus according to the present invention. In the figure, reference numeral 1 denotes a fixed abrasive wire saw, and the fixed abrasive wire saw 1 is supplied with a slurry 2 made of coolant. The ingot is cut by the fixed abrasive wire that is not used, and the slurry waste liquid 3 discharged from the fixed abrasive wire saw 1 is received by the liquid receiving container 4.

  In the figure, reference numeral 5 denotes a storage tank, and the storage tank 5 forms a first tank 5A and a second tank 5B which are partitioned on the left and right by an overflow wall 6 provided inside, and the first tank 5A has a lower side. A cyclone separator 7 having a tapered shape is provided.

  The slurry waste liquid 3 in the liquid receiving container 4 is supplied to a cyclone separator 7 provided in the first tank 5A by a waste liquid intake system path 9 provided with a pump 8. That is, the waste liquid intake passage 9 is connected so as to introduce the slurry waste liquid 3 into the tangential inlet 10 provided in the large-diameter portion of the tapered cyclone separator 7. The slurry waste liquid 3b having an increased slurry concentration is taken out from the small diameter end 11 of the separator 7, and the slurry waste liquid 3a having a reduced slurry concentration is discharged into the first tank 5A from the central port 12 on the large diameter side. It has become so.

  The small-diameter end 11 of the cyclone separator 7 is connected to a centrifuge 14 via a take-out line 13, and the slurry waste liquid 3 b having an increased slurry concentration from the small-diameter end 11 is solidified by the centrifuge 14. It is divided into the particles 15 and the slurry 2 in which the content of solid particles is reduced. The solid particles 15 are collected in the collection container 16, and the slurry 2 is collected in the slurry tank 17.

  The slurry 2 of the slurry tank 17 is supplied to the second tank 5B through a supply pipe 19 provided with a pump 18. The take-out line 13 and the supply pipe 19 are provided with specific gravity meters 23 and 24. By measuring the specific gravity with the specific gravity meters 23 and 24, the removal rate of the solid particles in the centrifuge 14 is obtained. Yes.

  The slurry 2 inside the second tank 5B is supplied to the fixed abrasive wire saw 1 by a slurry supply system passage 26 having a pump 25. A circulation passage 28 is provided for taking out the slurry 2 inside the second tank 5B by the pump 27 and returning it to the second tank 5B. A hydrometer 29 and a thermometer 30a are provided in the circulation passage 28. An attached viscometer 30 is provided.

  The circulation channel 28 is provided with a slurry discharge system path 33 for discharging the circulating slurry 2 as a waste slurry 31 to a waste slurry tank 32, and the circulation channel 28 and the slurry discharge system path 33 are provided with the slurry channel 31. Are provided with valves 34 and 35 for switching the slurry 2 to be discharged into the waste slurry tank 32. In the above description, the case in which the slurry discharge path 33 is connected to the circulation path 28 has been described. However, the slurry discharge path 33 so as to directly discharge the slurry 2 of the second tank 5B to the waste slurry tank 32. May be provided independently.

  The second tank 5B is provided with a new slurry supply system path 38 in which the new slurry 2a stored in the new slurry tank 36 is supplied by a pump 37. In FIG. 1, reference numeral 39 denotes a stirrer provided in the second tank 5B, and 40 denotes the slurry waste liquid 3a downward when the slurry waste liquid 3a in the first tank 5A flows into the second tank 5B over the overflow wall 6. The guide wall is guided so as to be stirred by the stirrer 39.

  In FIG. 1, reference numeral 41 denotes a controller. The controller 41 inputs the specific gravity detection value by the specific gravity meter 29 and the viscosity / temperature detection value by the viscometer 30 to which the thermometer 30 a is attached. The slurry concentration (a value related to the cutting performance of the fixed abrasive wire saw 1) in consideration of the solids particle size is detected. When the slurry concentration detected by the controller 41 reaches the specified concentration, the controller 41 operates the valves 34 and 35 to remove a predetermined amount of the slurry 2 in the second tank 5B. 31 is discharged to the waste slurry tank 32, and at the same time, the pump 37 is driven to supply the new slurry 2a stored in the new slurry tank 36 to the second tank 5B in the same amount as the waste slurry 31. As a result, the slurry concentration of the slurry 2 in the second tank 5B is restored to a specified concentration or less.

  Next, the operation of the above embodiment will be described.

  The slurry waste liquid 3 discharged from the fixed abrasive wire saw 1 to the liquid receiving container 4 is supplied to the cyclone separator 7 provided in the first tank 5 </ b> A through the waste liquid intake path 9 by the operation of the pump 8. Then, the slurry waste liquid 3b having an increased slurry concentration is taken out from the small-diameter end 11 of the cyclone separator 7, and the slurry waste liquid 3a having a reduced slurry concentration is taken in the first tank 5A from the central port 12 on the large-diameter side. To be discharged.

  The slurry waste liquid 3b having a high slurry concentration from the small-diameter end 11 of the cyclone separator 7 is supplied to the centrifuge 14 via the take-out path 13, whereby the solid particles 15 and the content of the solid particles are reduced. The solid particles 15 are collected in a collection container 16 and the slurry 2 is collected in a slurry tank 17. At this time, the higher the concentration of the supplied slurry, the higher the separation performance of the centrifugal separator 14. Therefore, as described above, the slurry waste liquid 3 b whose slurry concentration is increased by the cyclone separator 7 is supplied to the centrifugal separator 14. Thus, the centrifuge 14 effectively separates the solid particles 15.

  The slurry 2 collected in the slurry tank 17 by the centrifugal separator 14 is supplied to the second tank 5B through the supply pipe 19 by the operation of the pump 18, and the slurry 2 in the second tank 5B is supplied to the pump 25. As a result of the operation, the slurry is supplied to the fixed abrasive wire saw 1 through the slurry supply system 26 and is circulated for use.

  The specific gravity detection value from the specific gravity meter 29 provided in the circulation flow path 28 provided in the second tank 5B and the viscosity / temperature detection value from the viscometer 30 to which the thermometer 30a is attached are input to the controller 41. Therefore, the controller 41 detects the slurry concentration in consideration of the particle size of the solid content in the slurry 2.

  FIG. 2 compares the management of the slurry according to the present invention with the conventional management of batch processing of the slurry waste liquid, with the horizontal axis representing time and the vertical axis representing specific gravity. Here, in the management of the present invention, the slurry concentration that affects the cutting performance of the fixed abrasive wire saw 1 is detected by detecting the viscosity together with the specific gravity. That is, in the separation by the centrifugal separator 14, solid particles having a small particle diameter accumulate due to its characteristics. For this reason, although the specific gravity is not high, the fine particles increase and the viscosity becomes high. There is a problem that the cutting performance by the abrasive wire saw 1 is lowered, and in order to solve this problem, the slurry concentration in consideration of the particle size of the solid content in the slurry 2 is obtained and controlled.

  When the slurry concentration is lower than the prescribed concentration S shown in FIG. 2, the operation of supplying the slurry 2 in the second tank 5B to the fixed abrasive wire saw 1 as it is is continued. At this time, X in FIG. 2 is a limit value at which cutting with the fixed abrasive wire saw 1 can be performed stably, and the specified concentration S is close to the limit value X and stable cutting with the fixed abrasive wire saw 1 is performed. The maximum concentration possible.

  When the slurry concentration detected by the controller 41 reaches the specified concentration S in FIG. 2, the controller 41 operates the valves 34 and 35 to provide a predetermined amount of slurry 2 in the second tank 5B. The waste slurry 31 is discharged into the waste slurry tank 32, and at the same time, the pump 37 is driven to supply the new slurry 2a of the new slurry tank 36 to the second tank 5B by the same amount as the waste slurry 31. As a result, the slurry 2 in the second tank 5B is diluted with the new slurry 2a, and the slurry concentration is restored to the specified concentration S or less.

  By the above operation, the slurry 2 in the second tank 5B is always stably held below the specified concentration S in FIG. 2, and the slurry 2 having such a stable slurry concentration is supplied to the fixed abrasive wire saw 1. By doing so, the fixed abrasive wire saw 1 always achieves stable cutting.

  On the other hand, Y in FIG. 2 shows the conventional batch processing of slurry waste liquid. In the case of batch processing like the line Y, the slurry concentration gradually increases as the cutting operation is continued. Therefore, first, the slurry concentration at the end of cutting is set to be a value immediately before the limit value X, and the slurry concentration at the start of cutting is calculated by back calculation so that the set value at the end of cutting is maintained. Therefore, in the past, it was necessary to adjust the slurry concentration at the start of cutting to a very low value, which necessitates precise separation by a separation device such as a membrane filter, resulting in an increase in cost. Had the problem of doing.

  On the other hand, in the present invention, as shown in FIG. 2, the slurry concentration of the slurry 2 is adjusted to the specified concentration S close to the limit value X. Therefore, the slurry concentration is adjusted to the specified concentration using the centrifuge 14. It is easy to maintain a value close to S. That is, since the centrifuge 14 has the performance that the recovered amount increases as the concentration of the solid particles increases, the solid particles 15 are improved by supplying the slurry waste liquid 3b concentrated in the cyclone separator 7 to the centrifuge 14. Therefore, the slurry concentration can be easily maintained below the specified concentration S. Further, if the slurry concentration becomes higher than the specified concentration S even after the separation by the centrifugal separator 14, a part of the slurry 2 in the second tank 5B is discarded and a new new slurry 2a is supplied. Therefore, the slurry 2 can be easily and inexpensively managed, and there is an advantage that the slurry 2 supplied to the fixed abrasive wire saw 1 can always be stabilized. Further, it is preferable that the waste slurry 31 discharged to the outside when the slurry concentration exceeds the specified concentration S is provided with a membrane filtration device such as a swing separator to increase the coolant recovery rate. In this case, the membrane filtration device can be drastically reduced in comparison with the conventional batch type separation device.

  In addition, when the slurry waste liquid 3 from the fixed abrasive wire saw 1 provided in plurality is introduced into the first tank 5A, the slurry waste liquid 3a in the first tank 5A is supplied to the second tank 5B over the overflow wall 6. In addition, since the slurry waste liquid 3a in the first tank 5A is separated from the slurry waste liquid 3b having a high slurry concentration by the cyclone separator 7, the slurry waste liquid 3a having a low slurry concentration is used. Is not supplied to the second tank 5B. In this way, according to the storage tank 5 in which the first tank 5A and the second tank 5B are separated from each other by the overflow wall 6, the liquid delivery is simplified, and the first tank 5A and the second tank 5B are suitably applied to the processing of a large amount of slurry waste liquid 3. be able to.

  Further, the waste slurry 31 discharged to the waste slurry tank 32 is guided to a filter or the like and separated into solid and liquid, whereby the filtrate can be recovered as slurry and used effectively.

  Further, the wire saw slurry management device of the present invention is not limited to the above-described embodiment. For example, the first tank 5A and the second tank 5B may be separately provided without being integrally provided. Of course, various modifications can be made without departing from the scope of the present invention.

DESCRIPTION OF SYMBOLS 1 Fixed abrasive wire saw 2 Slurry 2a New slurry 3 Slurry waste liquid 3a Slurry waste liquid 3b Slurry waste liquid 5A 1st tank 5B 2nd tank 6 Overflow wall 7 Cyclone separator 14 Centrifuge 15 Solid particle 23, 24 Hydrometer 26 Slurry supply system Path 28 Circulating path 29 Hydrometer 30 Viscometer 31 Waste slurry 33 Slurry discharge path 38 New slurry supply path 41 Controller S Specified concentration

Claims (4)

  The first tank for receiving and storing the slurry waste liquid from the fixed abrasive wire saw, the centrifuge for separating the solid particles by introducing the slurry waste liquid in the first tank, and the solid particles separated by the centrifuge Specific gravity provided in a second tank for receiving and storing the slurry, a slurry supply system for supplying the slurry in the second tank to the fixed abrasive wire saw, and a circulation channel for taking out and circulating the slurry in the second tank Taking into account the particle size obtained from the viscosity of the solid content with respect to the concentration obtained from the specific gravity of the solid content in the slurry by incorporating the specific gravity detection value by the hydrometer and the viscometer and the viscosity detection value by the viscometer A controller for detecting the slurry concentration, a slurry discharge passage for discharging a part of the slurry in the second tank as waste slurry, and a new slurry supply passage for supplying new slurry to the second tank, The controller is configured to detect the detected slurry. As degree retains a defined concentration, slurry management device wire saw being characterized in that to perform the supply of a new slurry by the discharge and the new slurry supply line of the waste slurry by the slurry discharge pathway.   The first tank is provided with a cyclo separator, and the slurry waste liquid from the fixed abrasive wire saw is guided to the cyclone separator to supply the centrifugal separator with the slurry waste liquid whose concentration of solid particles is increased. The slurry management device for a wire saw according to claim 1.   3. The wire saw slurry management apparatus according to claim 1, wherein the specified concentration is a maximum concentration at which stable cutting with a fixed abrasive wire saw is possible. 4.   The said 1st tank and the 2nd tank are comprised integrally, The slurry waste liquid of the 1st tank was supplied to the 2nd tank via the overflow wall, The one of Claims 1-3 characterized by the above-mentioned. The wire saw slurry management apparatus according to one.

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