JPH11114825A - Moisture adjusting device for moisture-containing grinding lubricant and system for recycling grinding lubricant - Google Patents

Abstract

PROBLEM TO BE SOLVED: To allow application to a grinding lubricant formed of a water-soluble dispersion medium having low moisture content and a water-insoluble dispersion medium. SOLUTION: This moisture adjusting device is constituted to recover an abrasive grain-containing grinding lubricant used in grinding work by means of a wire was, a band saw, or water jet and to adjust the moisture of the grinding lubricant in adjustment for recycle. This moisture adjusting device is provided with a storage tank 11 for temporarily storing the recovered grinding lubricant, a moisture make-up means 13 for supplying water in the storage tank, and a moisture content monitoring means 12 installed in the storage tank 11 and capable of calculating the moisture content in the grinding lubricant by measuring the electrostatic capacity of the grinding lubricant in the storage tank 11. The moisture content monitoring means 12 detects the moisture content in the grinding lubricant. The moisture make-up means 13 supplies moisture to the grinding lubricant to adjust the moisture content of the grinding lubricant.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a water adjusting device for reusing a cutting fluid used for cutting an ingot of, for example, single crystal silicon, polycrystalline silicon, other compound semiconductors, ceramics, and the like. Related to a cutting fluid reuse system.

[0002]

2. Description of the Related Art Conventionally, when cutting an ingot of a silicon single crystal, a slurry-like cutting fluid obtained by mixing and dispersing abrasive grains such as SiC in a water-insoluble dispersion medium mainly composed of mineral oil is used. The cutting operation is performed while supplying the blade to the cutting device. Then, the cut silicon wafer is cleaned in a cleaning process to remove chips generated by the cutting and the attached cutting fluid, and are provided to the next step. The cutting fluid supplied to the blade portion of the cutting device and used for cutting the ingot is treated as waste.

[0003] However, the above-mentioned dispersion medium containing mineral oil as a main component is a flammable dangerous substance, and the storage quantity is restricted by the Fire Service Law. And the same applies to waste. Therefore, in recent years, various water-soluble abrasive dispersion media containing 40 to 60% of water have been developed and proposed in place of the non-water-soluble dispersion media for cutting. For example, JP-A-8-
Japanese Patent No. 57847 proposes a dispersion medium of abrasive grains in which a fatty acid amine obtained by reacting an alkanolamine with a higher fatty acid is uniformly mixed with an organic or inorganic bentonite aqueous solution. This dispersion medium avoids the danger of ignition by containing 50% or more of water.

As a method for maintaining the viscosity of a cutting fluid at a predetermined value using such a water-soluble dispersion medium, Japanese Patent Application Laid-Open No. 8-
No. 243920 proposes a method in which water is added to the cutting fluid by a slurry viscosity adjusting device to maintain the viscosity at a predetermined value. This slurry viscosity controller monitors the change in the water content of the cutting fluid due to the volatilization of water by measuring the electrical conductivity of the cutting fluid, and replenishes moisture as needed to adjust the viscosity of the slurry (cutting fluid). Is what you do.

[0005]

However, in cutting of a semiconductor material such as a silicon ingot, as the processing proceeds, conductive silicon chips and metal wear powder of a cutting portion of a cutting machine (in a wire saw). A large amount of wire abrasion powder or blade abrasion powder in a band saw is mixed. Then, the electrical conductivity of the cutting fluid is greatly affected by these.

Further, the electric conductivity of the cutting fluid is greatly affected by an electrolytic inorganic substance mixed from the outside, a temperature change, and the like. For this reason, when the water content of the cutting fluid is adjusted based on the electric conductivity, there is a great possibility that the water content of the adjusted cutting fluid will vary due to such contaminants and temperature changes.

[0007] The dispersion medium composition targeted by the slurry viscosity adjusting device disclosed in the above-mentioned JP-A-8-243920 has a water content of 40 to 60%, and therefore has relatively high electric conductivity. It is presumed that even if there is an error, the purpose of adjusting the water content and thus adjusting the viscosity can be sufficiently achieved.

However, as for the water-soluble abrasive dispersion medium currently used for silicon ingots and the like, polyethylene glycol and the like are used in order to cope with difficult processing due to the increase in diameter (8 → 12 → 16 inches) of silicon ingots. Containing 70% by weight or more is becoming mainstream. Therefore, the amount of water added to the abrasive dispersion medium to reduce flammability is small.

On the other hand, the applicant of the present invention has invented a cutting fluid using a water-insoluble abrasive dispersion medium which has solved the problem of flammability, and has filed a separate application. The cutting fluid using this water-insoluble dispersion medium does not use a water-soluble abrasive dispersion medium, but rather contains a small amount of water in the water-insoluble abrasive dispersion medium mainly composed of mineral oil. This solves the problem of the flammability of the water-insoluble dispersion medium described above. The cutting fluid using the water-insoluble dispersion medium has better adhesion to the cutting member than the cutting fluid using the water-soluble dispersion medium, and the quality of the cut product when used for cutting is good. is there.

With respect to the cutting fluid using the water-soluble dispersion medium having a small water content and the cutting fluid using the water-insoluble dispersion medium containing a small amount of water, when the cutting fluid is circulated and used for cutting the silicon ingot, In order to keep the flammability low, it is important to supplement the water that evaporates from the dispersion medium by circulating use.

However, the amount of water contained in the cutting fluid is about 20
% Or less, or a non-flammable water-insoluble dispersion medium containing a mineral oil as a base oil, because of its low electric conductivity, the electric conductivity as disclosed in the above-mentioned JP-A-8-243920. The moisture adjustment based on the measurement of the conductivity is greatly affected by the measurement error, and the measurement itself may not be performed in some cases.

In other words, the above slurry viscosity adjusting device is capable of adjusting the water content of a cutting fluid using a water-soluble dispersion medium as described above. Can be used, but the cutting fluid using a water-soluble dispersion medium having a small amount of water, or the water content of the cutting fluid using a water-insoluble dispersion medium containing a small amount of water, as separately filed by the present applicant. Cannot be used for adjustment.

An object of the present invention is to adjust the water content of the collected used cutting fluid to an appropriate value. It is an object of the present invention to provide a cutting fluid moisture adjusting device which can be applied to moisture control of a cutting fluid with a water-insoluble dispersion medium which has improved the problem, and a cutting fluid reusing system using the moisture adjusting device.

[0014]

SUMMARY OF THE INVENTION According to a first aspect of the present invention, there is provided a moisture control apparatus for recovering a cutting fluid containing abrasive grains used in processing by a wire saw, a band saw or a water jet and adjusting the cutting fluid to be reusable. A water adjusting device for adjusting the water content of the liquid, a storage tank for temporarily storing the collected cutting fluid, a water supply unit for supplying water into the storage tank, A water amount monitoring means that can calculate the amount of water in the cutting fluid by measuring the capacitance of the cutting fluid in the storage tank installed, and the water amount in the cutting fluid by the water amount monitoring means. Is detected and water is supplied to the cutting fluid by the water replenishing means to adjust the water content of the cutting fluid.

[0015] The cutting fluid recycling system of the second invention recovers the cutting fluid containing abrasive grains used in machining by a wire saw, band saw or water jet, and performs the cutting so that the cutting fluid can be reused. A cutting fluid reuse system for adjusting and adjusting the water content of a cutting fluid, wherein the cutting fluid supply device supplies the cutting fluid from the storage tank to the cutting machine, and the cutting machine. And a cutting fluid collecting means for collecting the cutting fluid used in the above from the cutting machine to the storage tank.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, a moisture adjusting device of the present invention and a cutting fluid reusing system using the device will be described in detail. Example (1) Configuration of Moisture Adjusting Apparatus The cutting fluid reuse system of the present embodiment circulates a cutting fluid containing abrasive grains such as SiC used for cutting with a multi-wire saw machine, and removes used cutting fluid. The water content is adjusted and the multi-wire saw machine is used again.

This cutting fluid reuse system includes a moisture conditioning device 1, a cutting fluid recovery device 21 for sending used cutting fluid from a multi-wire saw machine M (a general commercial machine) to the moisture conditioning device 1, and a moisture conditioning device 1. Cutting fluid supply device 22 for supplying the cutting fluid adjusted in the above to the multi-wire saw machine M
And consisting of As shown in FIG. 1, the moisture adjusting device 1 of this embodiment includes a cutting fluid tank 11 and a moisture monitoring device 1.
2, a water supply device 13, and an ion exchange water tank 14.

The cutting fluid tank 11 includes a cutting fluid collecting device 21.
Is connected to the multi-wire saw machine M, and receives the cutting fluid used for cutting in the multi-wire saw machine M through the cutting fluid recovery device 21. The cutting fluid tank 11 is connected to the multi-wire saw machine M by a cutting fluid supply device 22, and the cutting fluid whose moisture is adjusted in the cutting fluid tank 11 is supplied to the multi-wire saw machine M by the cutting fluid supply device 22. You.

Water content monitoring device 12 (Washing solution moisture meter GCM
-113 [Yamamoto Electric Instruments Co., Ltd.]) is a capacitance sensor 121 for measuring the capacitance of the cutting fluid.
And a temperature sensor 122 for measuring the temperature of the cutting fluid. The capacitance sensor 121 and the temperature sensor 122 are provided in the cutting fluid tank 11 and are immersed in the cutting fluid maintained at a predetermined water level in the cutting fluid tank 11.

The water content monitoring device 12 calculates the water content of the cutting fluid from the capacitance measured by the capacitance sensor 121. And this water content monitoring device 12
Can correct the water content of the cutting fluid calculated from the capacitance based on the temperature of the cutting fluid measured by the temperature sensor 122.

The hydration device 13 (Iwaki electromagnetic metering pump EH / R type (manufactured by Iwaki Co., Ltd.)) is connected to an ion exchange water tank 14 and receives supply of ion exchange water from the ion exchange water tank 14. . On the other hand, the hydration device 1
3 is provided with a water addition pipe 131 for replenishing the cutting fluid tank 11 with an appropriate amount of the ion-exchanged water.
The water addition pipe 131 is open at a position about 10 cm above the liquid level of the cutting fluid in the cutting fluid tank 11.

The water conditioning apparatus 1 and the cutting fluid recycling system of the present invention configured as described above are, for example, S
The water content of the cutting fluid obtained by mixing a predetermined amount of abrasive grains such as iC (silicon carbide) in a dispersion medium and uniformly dispersing the same can be controlled to a predetermined value. This device can be effectively applied to a cutting device such as a wire saw or a multi-wire or a multi-band saw in which a band saw is multiplexed.

(2) Performance Evaluation of Moisture Adjustment Device for Cutting Fluid Using Water-Soluble Dispersion Medium In Performance Evaluations 1 and 2, the performance of the moisture adjustment device 1 for cutting fluid using a water-soluble dispersion medium was evaluated. Perform an evaluation. In the performance evaluation 1, the correction based on the temperature of the cutting fluid was not performed in the calculation of the water content in the water content monitoring device 12, the performance evaluation 2 was performed in the case where the temperature correction was performed, and in the comparative example 1, no water adjustment was performed. Is the case.

(I) Performance Evaluation 1 As the cutting fluid used for the evaluation, prepared product A of a water-soluble dispersion medium composition shown in Table 1 and Shinanorandom GP # 600T of GC abrasives [Shinano Electric Smelting ( 1) by weight
The water-soluble cutting fluid 1 prepared by mixing with the above was used. And
In the moisture adjusting apparatus 1 of the present embodiment, the management amount of the cutting fluid was set to 10%, and the operation was performed while controlling the cutting fluid at 25 to 28 ° C. by the heat exchanger of the multi-wire saw machine M. However, in the calculation of the water content of the cutting fluid in the water content monitoring device 12, the correction based on the temperature of the cutting fluid was not performed.

Table 2 shows the results of the capacitance value of the water-soluble cutting fluid 1 and the actual water content measured by the water content monitoring device 12 during the operation of the present device. The actual water content of the water-soluble cutting fluid 1 was sampled and measured by a dehydrated xylol method.

[0026]

[Table 1]

[0027]

[Table 2]

(Ii) Performance evaluation 2 The water content of the water-soluble cutting fluid 1 is corrected by the water content monitoring device 12 according to the temperature of the cutting fluid to calculate the water content of the cutting fluid. Was driven. Table 2 shows the results.

(Iii) Comparative Example 1 With respect to the water-soluble cutting fluid 1, the same operation as in the performance evaluation 1 was performed without operating the water supply device 13. Table 2 shows the results.
Shown in

(3) Performance Evaluation of Moisture Adjustment Device for Cutting Fluid Using Non-Water-Insoluble Dispersion Medium In Performance Evaluations 3 and 4, the moisture adjustment device 1 for cutting fluid using a non-water-soluble dispersion medium was used. Is evaluated. The performance evaluation 3 is a case where the correction based on the temperature of the cutting fluid is not performed in calculating the water content in the water content monitoring device 12, the performance evaluation 2 is a case where the temperature correction is performed, and the comparative example 2 is a case where no water adjustment is performed. It is.

(I) Performance Evaluation 3 As the cutting fluid used for the evaluation, a preparation B of a water-insoluble dispersion medium composition having the composition shown in Table 1 and a Shinanorandom GP # 600T GC abrasive [Shinano Electric Smelting & Refining Co., Ltd. Co., Ltd.]
A water-insoluble cutting fluid 2 adjusted to 1.25 was used. Then, in the moisture adjusting device 1 of the present embodiment, the control moisture amount of the cutting fluid was set to 2%, and the operation was performed in the same manner as the performance evaluation 1. However, in the calculation of the water content of the cutting fluid in the water content monitoring device 12, the correction based on the temperature of the cutting fluid was not performed. Table 2 shows the results of the capacitance value of the water-insoluble cutting fluid 2 and the actual water content measured by the water content monitoring device 12 during the operation of the present device.

(Ii) Performance evaluation 4 For the water-insoluble cutting fluid 2, the water content monitoring device 12 corrects the water content according to the temperature of the cutting fluid to calculate the water content of the cutting fluid. The same operation was performed. Table 2 shows the results.

(Iii) Comparative Example 2 With respect to the water-insoluble cutting fluid 2, the same operation as the performance evaluation 3 was performed without operating the water supply device 13. Table 2 shows the results.

(4) Effects of the water adjusting device From Table 2, it can be seen from Table 2 that the water content of the water-soluble cutting fluid 1 was reduced to 6% after 7 hours in Comparative Example 1 in which no water was supplied. When the moisture adjustment device 1 was used, the target value was 15% when the correction based on temperature was not performed (performance evaluation 1), and 11% when the correction based on temperature was performed (performance evaluation 2). It keeps the value close to%.

In the case of the water-insoluble cutting fluid 2, even when the water content was reduced to 0.1% after 7 hours in the comparative example 2, the temperature was not corrected (performance evaluation 3). ) Is 1.8%, and when correction by temperature is performed (performance evaluation 2), 1.9% is maintained at a value close to the target value of 2%.

[Other Embodiments] The present invention is not limited to the above-described specific embodiments, but takes other embodiments in which various modifications are made within the scope of the present invention in accordance with the purpose and application. be able to. For example, the shape of the capacitance sensor for detecting the capacitance of the cutting fluid and the current and voltage to be used are not particularly limited.

Further, in order to improve the accuracy of the capacitance measurement, the temperature and humidity of the outside air, the density, temperature and p
H, slurry tank capacity, machining conditions and progress of machining are also measured at the same time, and the data is subjected to a correction process using a CPU or the like, and stored and used in a ROM or the like. , Which falls within the scope of the present invention. In addition, there is no particular limitation on the installation location of the sensor portion for measuring the capacitance, as long as the sensor portion is immersed in a uniform cutting fluid.

Next, as the water supply device 13, any method capable of supplying water to the cutting fluid may be used. For example,
A method in which an electromagnetic valve or the like is directly installed and controlled in a tap water pipe or a water pressure supply pipe, or a method in which an operating state of a gear pump, a diaphragm pump, a water flow pump, a piston pump, or the like is controlled is also preferable. Tap water can be used as the water to be used, but the use of ion-exchanged water is preferred.

[0039]

As described above, the apparatus for adjusting the water content of a cutting fluid according to the present invention employs a water content monitoring device for calculating the water content through measurement of the capacitance of the cutting fluid. The water adjustment error due to the influence of cutting powder of the object to be cut, wear of the blade part of the cutting machine, electrolytic inorganic substances mixed into the cutting fluid from the outside, temperature, etc. is smaller than that of the conventional device that calculates the water content by . For this reason, not only the suppression of the onset of flash point due to the water evaporation of the cutting fluid due to the water-soluble dispersion medium and the adjustment of the viscosity are possible, but also the cutting fluid with the water-insoluble dispersion medium composition characterized by containing water. Can also be applied to the suppression of flash point development and viscosity adjustment.

Therefore, if the water adjusting device of the present invention and the cutting fluid reusing system using the water adjusting device are used, a water-soluble abrasive dispersion medium may be used instead of an oil type abrasive dispersion medium used for a wire saw or a band saw. A dispersion medium and a non-flammable water-insoluble cutting oil can be used, and the water content can be adjusted and reused.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of a moisture adjusting device and a cutting fluid reuse system using the moisture adjusting device.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1; Moisture adjustment device, 11; Cutting fluid tank, 12; Moisture amount monitoring device, 121; Capacitance sensor, 122; Temperature sensor, 13;
4; ion exchange water tank, 21; cutting fluid recovery device, 2
2: Cutting fluid supply device, M: Multi-wire saw machine.

Claims (2)

[Claims] 1. A water adjusting device for adjusting the water content of a cutting fluid including a cutting fluid containing abrasive grains used in processing by a wire saw, a band saw or a water jet when the cutting fluid is adjusted to be reusable. A storage tank for temporarily storing the collected cutting fluid,
A water supply means for supplying water into the storage tank, and a water installed in the storage tank and capable of calculating the amount of water in the cutting liquid by measuring the capacitance of the cutting fluid in the storage tank. Volume monitoring means, wherein the water content monitoring means detects the water content in the cutting fluid, and the water replenishment means supplies water to the cutting fluid to adjust the water content of the cutting fluid. Moisture controller. 2. Cutting which collects a cutting fluid containing abrasive grains used in processing by a wire saw, a band saw or a water jet, adjusts the water content of the cutting fluid so that the cutting fluid can be reused, and sends it out. A liquid recycling system, comprising: the moisture adjusting device according to claim 1; a cutting fluid supply unit configured to supply a cutting fluid from the storage tank to the cutting machine; and a cutting fluid used in the cutting machine. And a cutting fluid collecting means for collecting the cutting fluid into the storage tank.