JP6619777B2 - Generation method of water-soluble cutting and grinding fluid - Google Patents

Description

The present invention relates to a method and apparatus for producing a water-soluble cutting / grinding fluid used during cutting / grinding machining, and more particularly, by electrolyzing water having different water qualities (conductivity, total hardness, etc.). In the case of reducing water, in order to obtain a water-soluble cutting / grinding fluid that maintains sterilization and excellent machining performance by maintaining the reduction potential after electrolysis regardless of the water quality for as long as possible. it relates to the generation how.

In cutting / grinding machining, a cutting / grinding fluid is used for the purpose of cooling, lubrication, chip flow and the like.
This cutting / grinding fluid is roughly classified into oily and water-soluble. Oily liquid is mineral oil and has excellent lubricity, but there are fires, environmental pollution problems during disposal, and stickiness during use. On the other hand, most of the water-soluble liquids are water, which is advantageous with few oily problems.
However, water-soluble liquids have a certain level of stickiness, which can contaminate processing machines, cause bacteria to develop due to use for a certain period of time, cause skin irritation, and rot to produce a strange odor. There is also a negative impact on the environment at the time of disposal.

In order to make water-soluble cutting / grinding fluid with excellent properties, tap water, industrial water (groundwater) or their softened water or used liquid is subjected to electrolysis treatment to reduce water. Prevents corruption and improves processability.
A comparison of reduced water and mineral oil is as follows.
1. Heat of vaporization: reduced water 586 cal / g, mineral oil 90 cal / g or less, ethanol 93 cal / g, and reduced water is far superior.
2. Specific heat: 1.00 cal / g · deg of reduced water, 0.44 cal / g · deg of mineral oil, and 0.57 cal / g · deg of ethanol, the reduced water is most difficult to warm and hard to cool.
3. Thermal conductivity: Reduced water 0.51 W / m / K, mineral oil 0.12 W / m / K, ethanol 0.18 W / m / K, and reduced water is most easily transferred.
As described above, the reduced water has a larger value than mineral oil in any of heat of vaporization, specific heat, and thermal conductivity, and has excellent properties as a cutting / grinding fluid.

  As a method for obtaining reduced water by electrolysis, a method shown in Patent Document 1 is known. According to the method described in Patent Document 1, a pair of AC electrode plates and two ground electrode plates are inserted into a target aqueous grinding / cutting fluid, and an AC power supply is passed through the AC electrodes to generate high frequency AC. When performing electrolysis, FM modulation with a fluctuation range of ± 3 to 5 KHz is applied around an oscillation frequency of about 5 to 100 KHz, and a random signal generator is built in. Water-based grinding / cutting fluid characterized by generating electric field interference by generating a part that changes up and down, creating shock waves, increasing the amount of hydrogen generated by the electrolysis and generating oxygen reduced to nanobubbles This is an electrolysis method.

The inventors measured the time-dependent changes in redox potential in Philippine water (A), Thai water (B), and Japanese tap water (C) under the same conditions as shown in FIGS. 2 and 3. Thus, the result shown by the different characteristic curve of the Philippine water (A1: thin dotted line), the Thai water (B1: thin dotted line), and the Japanese tap water (C: thin solid line) was obtained.
Conditions / Container: Alkaline water production system / Water: Filipino water (A), Thai water (B), Japanese tap water (C)
-Water volume: 257 liters-Room temperature: 25 ° C
・ Pulse wave: 10kHz, 15V, 7A

In these characteristic curves, the time required for Philippine water (A) to reach a reduction potential of −250 mV, which is necessary as a water-soluble cutting / grinding fluid, from the initial value (+216.0 mV) is as shown by the characteristic line (A1). About 50 minutes. Thereafter, when the electrolysis treatment was stopped, as shown by the characteristic line (A1), it returned to −170 mV, which was desired as a water-soluble cutting / grinding fluid, in about 9 hours, and further returned to 0 mV in about 30 hours.
Thai water (B) takes about 80 minutes from the initial value (+147.0 mV) to the reduction potential of -250 mV required as a water-soluble cutting / grinding fluid, as shown by the characteristic line (B1). It was. Thereafter, when the electrolysis treatment was stopped, as shown by the characteristic line (B1), it returned to −170 mV, which was desired as a water-soluble cutting / grinding fluid, in about 25 hours, and further returned to 0 mV in about 40 hours.
On the other hand, the time required for Japanese water (C) to reach the reduction potential of −250 mV required as a water-soluble cutting / grinding fluid from the initial value (+521.0 mV) is about It was 120 minutes. Thereafter, when the electrolysis treatment was stopped, as shown by the characteristic line (C2), −170 mV desired as a water-soluble cutting / grinding fluid was continued for about 65 hours, and then returned to 0 mV in about 195 hours.

  Thus, Philippine water (A) and Thai water (B) have higher water quality, that is, conductivity or total hardness than Japanese water, and reach -250 mV in a short time. There was a problem that the working potential (for example, 40 hours or more) required to return to the original potential rapidly and to maintain −170 mV, which is desired as a water-soluble cutting / grinding fluid, cannot be maintained.

JP 2013-46936 A

As a result of various studies, the present inventor has made an electrolysis treatment time required to reach a reduction potential (for example, -250 mV) desired as a water-soluble cutting / grinding fluid as long as possible (for example, comparable to that of Japanese water). 120 minutes), it was found that the reduction potential desired as a water-soluble cutting / grinding fluid after the electrolysis treatment was stopped can be extended several times that of the prior art. In addition, the time for electrolyzing the target water to the reduction potential desired as the water-soluble cutting / grinding fluid should be controlled by the pulse width to be applied according to the water quality, particularly the conductivity or total hardness. There was found.
The present invention is to obtain a water-soluble cutting / grinding fluid that maintains sterilization and excellent machining performance by maintaining the reduction potential after the electrolysis treatment as long as possible regardless of the water quality. it is an object to provide a production how.

  The present invention applies water to the reducing electrode 18, applies a reducing potential to the reducing electrode 19, and applies the reducing potential to the reducing electrode 19 in a method for producing a water-soluble cutting / grinding fluid that is electrolyzed into reduced water. The pulse voltage width is adjusted according to the nature of the water to be reduced.

When the electrical conductivity as the nature of the water to be reduced is high, the pulse voltage width applied to the reducing electrode 19 is reduced according to the high electrical conductivity.
Further, when the total hardness as the nature of the water to be reduced is high, the pulse voltage width applied to the reduction electrode 19 is reduced according to the total hardness.
More specifically, the pulse voltage applied to the reduction electrode 19 is reduced in inverse proportion to the conductivity or the total hardness as the nature of the water to be reduced, so as to extend the time to reach a predetermined reduction potential. To.

An apparatus for producing a water-soluble cutting / grinding fluid that puts water into the reduction tank 18 and applies a reduction potential to the reduction electrode 19 and electrolyzes it into reduced water.
A PWM oscillation circuit 10 for oscillating a pulse signal for obtaining a pulse voltage to be applied to the reduction electrode 19;
Time to reach the predetermined reduction potential by reducing the pulse voltage width applied to the reduction electrode 19 in inverse proportion to the conductivity or the total hardness as the nature of the water to be reduced, connected to the PWM oscillation circuit 10 Memory 21 for storing data for extending
And a waveform shaping circuit 11 for shaping a pulse signal generated by the PWM oscillation circuit 10 so as to be applied to the pair of reduction electrodes 19.

According to invention of Claim 1,
In a method for producing a water-soluble cutting / grinding fluid by putting water in a reduction tank, applying a reduction potential to the reduction electrode, and electrolyzing it into reduced water,
The electric conductivity X (μs / cm) of water to be reduced is obtained, and when the pulse voltage width applied to the reducing electrode is Y (%) , it is obtained from the equation : Y = C1 / X (C1 is a constant 80 ) that is applied to the potential reduction electrode of the pulse voltage width Y, by extending the time to reach a predetermined negative reduction potential to a negative reduction potential of the electrolysis stopped after the water-soluble cutting and grinding fluid sustainability is As a result, the reduction potential after the electrolysis treatment can be maintained for as long as possible regardless of the water quality, and a water-soluble cutting / grinding fluid that maintains sterilization and excellent machining performance is obtained. be able to. Specifically, the pulse voltage applied to the reduction electrode is reduced in inverse proportion to the high conductivity as the nature of the water to be reduced, and the time to reach the reduction potential can be extended to about the same level as that of soft water. It is possible to obtain a water-soluble cutting / grinding fluid that can be sterilized and has excellent machining performance.

According to the invention of claim 2 Symbol placement,
Since the pulse voltage width to be applied to the reduction electrode is set by a method that is controlled by the duty ratio (pulse width) of the pulse signal, the driving current can be kept constant by this method.

Is a characteristic diagram showing the relationship between the pulse width to be applied with the water quality definitive water-soluble cutting and grinding fluid produced how according to the present invention (conductivity or total hardness). It is a characteristic figure of the reduction potential of three kinds of water (Philippines, Thailand, Japan). It is a figure showing the measured value of the reduction potential of three types of water (Philippines, Thailand, Japan). Examples of the water-soluble cutting and grinding fluid produced how according to the present invention is an electrical circuit block diagram showing. FIG. 4 is an output waveform diagram of each part when the pulse width is controlled by the PWM oscillation circuit 10 in FIG. 4.

The present invention
In a method for producing a water-soluble cutting / grinding fluid in which water is put into the reduction tank 18 and a reduction potential is applied to the reduction electrode 19 and electrolyzed to obtain reduced water, the pulse voltage width applied to the reduction electrode 19 is Adjust according to the nature of the water to be reduced.
The pulse voltage width applied to the reduction electrode 19 is reduced according to the high conductivity as the nature of the water to be reduced.
Further, the width of the pulse voltage applied to the reduction electrode 19 is reduced according to the total hardness as the nature of the water to be reduced.
More specifically, the pulse voltage applied to the reduction electrode 19 is reduced in inverse proportion to the conductivity or the total hardness as the nature of the water to be reduced, so as to extend the time to reach a predetermined reduction potential. To.

An apparatus for producing a water-soluble cutting / grinding fluid that puts water into the reduction tank 18 and applies a reduction potential to the reduction electrode 19 and electrolyzes it into reduced water.
A PWM oscillation circuit 10 for oscillating a pulse signal for obtaining a pulse voltage to be applied to the reduction electrode 19;
Time to reach the predetermined reduction potential by reducing the pulse voltage width applied to the reduction electrode 19 in inverse proportion to the conductivity or the total hardness as the nature of the water to be reduced, connected to the PWM oscillation circuit 10 Memory 21 for storing data for extending
It is assumed that a waveform shaping circuit 11 for shaping a pulse signal generated by the PWM oscillation circuit 10 to be applied to the pair of reduction electrodes 19 is provided.

  In FIG. 4, the apparatus for realizing the water-soluble cutting / grinding fluid generation method of the present invention includes a PWM (pulse width control) oscillation circuit 10, a waveform shaping circuit 11, a drive circuit 12, and a superimposed DC power supply 13. And a driving DC power source 14, a current detection circuit 15, an amplification circuit 16, a switching circuit 17, a reduction tank 18, and a memory 21.

The PWM oscillation circuit 10 oscillates a pulse (pulsation) signal as shown in FIG. 5A, the oscillation frequency f can be adjusted in the range of 5 kHz to 30 kHz, and the on / off duty ratio d is , And can be adjusted in the range of 0 to 100%. The memory 21 connected to the PWM oscillation circuit 10 stores water quality data of various types, each place, and each country. This water quality data includes conductivity data, total hardness data (data based on Ca ion concentration and Mg ion concentration), other metal ion concentrations, etc., and based on these data, the pulse width is controlled from the characteristic diagram in FIG. Is output to the PWM oscillation circuit 10.
As shown in FIG. 5B, the waveform shaping circuit 11 separates the pulse signal of the PWM oscillation circuit 10 into an odd-numbered pulse signal b-1 and an even-numbered pulse signal b-2.
The superimposed DC power supply 13 outputs a substantially flat DC voltage v1 to be superimposed on the pulse signal.
The drive DC power supply 14 controls the peak voltage v1 of the pulse signal.
The drive circuit 12 superimposes a substantially flat DC voltage v2 set by the superimposed DC power supply 13 on the pulse voltage v1 set by the drive DC power supply 14, and shows them as c-1 and c-2 in FIG. As described above, the signals are output as signals that are 180 degrees out of phase.

The reduction tank 18 is provided with two reduction electrodes 19 facing each other, and a common electrode 20 is provided between the reduction electrodes 19. These reduction electrodes 19 are not limited to a pair of two, but may be a plurality of pairs.
A current detection circuit 15 made of a resistor or the like is inserted between the common terminal c-0 of the drive circuit 12 and the common electrode 20, and an amplification circuit 16 is connected to both ends of the current detection circuit 15, and the amplification circuit 16 The PWM oscillation circuit 10, the superimposed DC power supply 13, and the driving DC power supply 14 are selectively connected to the output side of the memory 21 via a switching circuit 17. The duty ratio d, the voltage value v2, and the voltage value v1 are selectively switched.

First, in order to investigate the characteristics of Philippine water (A), Thai water (B), and Japanese tap water (C), water is put into the reduction tank 18 regardless of the quality of these waters. And start electrolysis under the same conditions.
Specifically, 257 liters is placed in the reduction tank 18, the circuit is switched on, and a current of 7A is supplied to start electrolysis.
For example, the PWM oscillation circuit 10 outputs a pulse signal with a duty ratio of 80% at 10 kHz. This pulse signal is separated into an odd-numbered pulse signal b-1 and an even-numbered pulse signal b-2 in FIG. 5B by the waveform shaping circuit 11, and sent to the drive circuit 12. The application of the pulse voltage is to add permeability and affinity to water.
The superimposed DC power supply 13 sets a substantially flat DC voltage v <b> 2 of 10 to 24 V and sends it to the drive circuit 12.
The drive DC power supply 14 is set so that the peak value v1 when the DC voltage v2 is superimposed on the pulse signal is 48V, and sends it to the drive circuit 12.
A voltage indicated by c-1 and c-2 in FIG. 5C in which a substantially flat DC voltage of 10 to 24 V is superimposed on the pulse signal of the drive circuit 12 is applied between the two reduction electrodes 19.

When the change over time of the oxidation-reduction potential when a voltage in which a substantially flat DC voltage of 10 to 24 V is superimposed on the pulse voltage is applied to the water-soluble cutting / grinding fluid in the reduction tank 18, Filipino water (A ), Thai water (B), Japanese tap water (C), as shown in the data shown in FIG. 3 and the line graph shown in FIG. 2, the water in the Philippines (A1), the water in Thailand (B1), and the water in Japan A characteristic curve of tap water (C) was obtained.
Specifically, the characteristic curve (A1) of water (A) in the Philippines is about 50 minutes until the initial value reaches the minus direction from +216.0 mV and reaches -250.0 mV, which is necessary as a water-soluble cutting and grinding fluid. Met. Thereafter, when the electrolysis treatment was stopped, as shown by the characteristic line (A1), it returned to −170 mV, which was desired as a water-soluble cutting / grinding fluid, in about 9 hours, and further returned to 0 mV in about 30 hours.

  The characteristic curve (B1) of water (B) in Thailand was about 80 minutes until the initial value went from -147.0 mV in the negative direction until it reached -250.0 mV, which is necessary as a water-soluble cutting / grinding fluid. Thereafter, when the electrolysis treatment was stopped, as shown by the characteristic line (B1), it returned to −170 mV, which was desired as a water-soluble cutting / grinding fluid, in about 25 hours, and further returned to 0 mV in about 40 hours.

  On the other hand, the water (C) in Japan was about 120 minutes from the initial value (+521.0 mV) until reaching -250 mV, which is necessary as a water-soluble cutting / grinding fluid, as indicated by the characteristic line (C). It was. Thereafter, when the electrolysis treatment was stopped, as shown by the characteristic line (C2), −170 mV desired as a water-soluble cutting / grinding fluid was continued for about 65 hours, and then returned to 0 mV in about 195 hours.

Next, the operation of the present invention will be described.
The cause of the above is that the water in the Philippines (A) and the water in Thailand (B) have a higher water quality, that is, conductivity or total hardness than that of Japanese water. It was found that when it was stopped, it quickly returned to its original potential and could not sustain the desired -170 mV as a water-soluble cutting and grinding fluid.
Therefore, in order to maintain the reduction potential desired as the water-soluble cutting / grinding fluid in the vicinity of −250 mV, if the electrolysis time for reaching the reduction potential to near −250 mV is lengthened, the water-soluble cutting / grinding fluid is correspondingly increased. It was found that the desired reduction potential can be sustained.

Philippine water (A) and Thai water (B) reach -250 mV in a short time because water quality, that is, conductivity or total hardness is higher than that of Japanese water. Returning to the original potential, it was found that -170 mV, which is desired as a water-soluble cutting / grinding fluid, cannot be maintained for a predetermined time (for example, 40 hours or more).
As a result of repeated experiments, as shown in FIG. 1, the conductivity (or total hardness) X and the applied pulse width Y are approximately inversely proportional to each other as shown in the following equation. By applying the electrolysis treatment time required to reach the reduction potential (for example, -250 mV) desired as a water-soluble cutting / grinding fluid, as long as possible (for example, 120 minutes, which is about the same as water in Japan) They discovered that the reduction potential desired as a water-soluble cutting / grinding fluid can be extended several times the conventional reduction potential.
XY = C1 (about 80 (1 ± 0.2) for conductivity) or XY = C2 (about 20 (1 ± 0.2) for full hardness)
It becomes.
In addition, since the property of water is not represented correctly only by electrical conductivity or total hardness, the constant C1 or C2 was set to (1 ± 0.2).

Based on this equation, the water (A) in the Philippines has a conductivity of X = 408 (μ / cm), so it is controlled by the PWM oscillation circuit 10 and applied with a potential having a pulse width of Y = about 20%. The same applies to the case of total hardness.
Further, based on this equation, Thai water (B) has a conductivity of X = 345 (μ / cm), so that it is controlled by the PWM oscillation circuit 10 to apply a potential having a pulse width of Y = about 23%. . The same applies to the case of total hardness.

Data (Fig. 3) and characteristic curve (Fig. 2) for Philippine water (A) and Thai water (B) measured under these conditions are characteristic line (A2: thick one-dot chain line) and (B2), respectively. : Thick dotted line)
As is clear from FIG. 2 and FIG. 3, in the Philippine water characteristic line (A2) after adjusting the pulse width, the time is extended to about 110 minutes until it reaches -250.0 mV required as a water-soluble cutting and grinding fluid. Then, after stopping the electrolysis process, it returns to -170 mV, which is desired as a water-soluble cutting / grinding fluid, in about 40 hours, and further returns to 0 mV in about 95 hours, and is about three times as long as the conventional method. became.
Moreover, in the characteristic line (B2) of Thailand water after the pulse width adjustment, the time is extended to about 120 minutes until it reaches -250.0 mV, which is necessary as a water-soluble cutting / grinding liquid, and then the electrolysis process is stopped. After that, in about 45 hours, it returned to -170 mV, which was desired as a water-soluble cutting / grinding fluid, and further returned to 0 mV in about 120 hours.

  In the above embodiment, in order to keep the driving current constant, the method is controlled only by the duty ratio (pulse width) of the pulse signal. However, (1) the method of controlling by the duty ratio (pulse width) of the pulse signal is superimposed. A method of combining the methods controlled by the voltage v2, (2) a method of combining the method controlled by the duty ratio (pulse width) of the pulse signal and the method controlled by the peak voltage v1, and (3) the duty ratio of the pulse signal (pulse Width), a method of controlling with the superimposed voltage v2, and a method of controlling with the peak voltage v1.

  In the above embodiment, the water is Philippine water (A), Thai water (B), Japanese tap water (C), but any water having different water quality (conductivity or total hardness), for example, current cutting -Coolant fluid used for grinding and water-soluble cutting / grinding fluid currently used (water, emulsion, soluble, solution, synthetic etc. mixed and diluted) can also be used.

  DESCRIPTION OF SYMBOLS 10 ... PWM oscillation circuit, 11 ... Waveform shaping circuit, 12 ... Drive circuit, 13 ... Superimposed DC power supply, 14 ... Drive DC power supply, 15 ... Current detection circuit, 16 ... Amplification circuit, 17 ... Switching circuit, 18 ... Reduction tank, 19 ... Reduction electrode, 20 ... Common electrode, 21 ... Memory.

Claims (2)

In a method for producing a water-soluble cutting / grinding fluid by putting water in a reduction tank, applying a reduction potential to the reduction electrode, and electrolyzing it into reduced water,
The electric conductivity X (μs / cm) of water to be reduced is obtained, and when the pulse voltage width applied to the reducing electrode is Y (%) , it is obtained from the equation : Y = C1 / X (C1 is a constant 80 ) that is applied to the potential reduction electrode of the pulse voltage width Y, by extending the time to reach a predetermined negative reduction potential to a negative reduction potential of the electrolysis stopped after the water-soluble cutting and grinding fluid sustainability is A method for producing a water-soluble cutting / grinding fluid characterized by being made as described above. Pulse voltage width to be applied to the reduction electrode, the method generates a water-soluble cutting and grinding fluid according to claim 1, characterized in that so as to set in a way that controls a duty ratio of the pulse signal (pulse width).

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