JP3093984B2 - Liquid management method of water-soluble processing fluid - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for managing a water-soluble working fluid, and more particularly to a method for maintaining the performance of a water-soluble working fluid. In particular, the present invention relates to a liquid management method for removing acidic substances generated during use by electrodialysis to prevent decay and deterioration of functions due to propagation of microorganisms or fungi.

[0002]

2. Description of the Related Art In the industrial fields such as machining, rolling, forging, and heat treatment, various working fluids are used for lubrication, cooling, and the like. In particular, water-soluble working fluids are frequently used due to their flame-retardant characteristics. ing. Specifically, water-soluble machining fluids such as water-soluble cutting oil, grinding oil, forging-type lubrication fluid, quenching fluid, and hydraulic oil are used. These water-soluble processing liquids are mainly composed of organic substances such as glycols and oils and fats, and are dissolved or dispersed in water. The pH of the liquid is generally adjusted to 9 to 11 to be weakly alkaline.

[0003] The pH of a water-soluble processing fluid gradually decreases with use, and microorganisms eventually propagate to rapidly decompose the water-soluble processing liquid, causing odors and deteriorating the function of the processing liquid. . Further, in the case of a water-soluble processing liquid, various salts are likely to accumulate due to being brought in from the outside or the like, and accordingly, corrosion of the processing apparatus and the workpiece is easily generated. Therefore, in order to use the water-soluble processing liquid stably for a long time, p
It is necessary to maintain a weak alkalinity of H and to manage the liquid to prevent accumulation of chloride ions and the like which cause corrosion.

Conventionally, electrolytic treatment has been proposed as a method for alkalizing water. For example, Japanese Patent Application Laid-Open No. 5-174242 describes that sterilization is performed simultaneously with generation of alkaline water by diaphragm electrolysis of tap water. . On the other hand, as a method for preventing salts from accumulating in water, for example, Japanese Patent Application Laid-Open No. Hei 7-091879 describes that various salts can be removed by electrodialysis of cooling water in a plant or the like with an ion exchange membrane.

[0005]

However, Japanese Patent Application Laid-Open No. Hei 5-174242 aims to reform tap water and does not treat water-soluble working fluid. Also, JP-A-7
Japanese Patent Publication No. 0991879 also manages cooling water and does not teach liquid management of a water-soluble working fluid. An object of the present invention is to provide a liquid management method of a water-soluble processing fluid that can prevent rot and deterioration of the function of the water-soluble processing liquid and can stably maintain the quality of the water-soluble processing liquid for a long period of time.

[0006]

Means for Solving the Problems The present inventor considered that the organic component contained in the water-soluble processing liquid was spoiled or oxidized to form an acidic component, which caused the pH of the water-soluble processing liquid to decrease. . Then, it was considered that the generated acidic component can be removed by electrodialysis or the like because it exists as an ion in the water-soluble processing liquid. In addition, since the corrosive component brought in from the outside with use is also a salt, it was considered that it was present as an ion in the water-soluble processing liquid and could be removed by electrodialysis or the like.

[0007] The present inventors have considered that take advantage of electrodialysis liquid management of the water-soluble working fluid, the result of trial and error, and completed the present invention. That is, the method for managing a water-soluble working fluid of the present invention uses a porous membrane or an anion exchange membrane as a dialysis membrane, and the water-soluble working fluid is supplied to a cathode chamber of an electrodialysis apparatus in which an anode chamber and a cathode chamber are separated by the dialysis membrane. Is supplied to the anode chamber, and electrodialysis is performed to weaken the pH of the water-soluble processing liquid.
It is characterized in that it is maintained at a lukety pH. When the management method of the present invention is carried out, the organic acid generated in the water-soluble processing fluid and halogen ions, sulfate ions and the like which are mixed in as corrosive components are removed from the water-soluble processing liquid, and the water-soluble processing liquid is regenerated.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION In the method for managing a water-soluble working fluid of the present invention, a porous membrane or an anion exchange membrane is used as a dialysis membrane. The porous membrane is preferably a membrane having pores having a pore size of about 0.01 to 0.1 μm. As such a membrane, a fluororesin porous membrane or the like can be used. The anion exchange membrane is a membrane through which anions can pass and cations cannot pass, and a specific membrane such as APS-3 manufactured by Asahi Glass Co., Ltd. can be used as the anion exchange membrane.

In the electrodialysis apparatus used in the present invention, the dialysis membrane is used to partition an anode chamber and a cathode chamber, and a cathode and an anode are arranged in the anode chamber and the cathode chamber, respectively. The electrodialysis apparatus can be incorporated in a tank storing a water-soluble processing liquid or in an apparatus using a water-soluble processing liquid, or can be provided independently of these apparatuses.

[0010] A water-soluble working fluid is charged into the cathode chamber of this electrodialysis apparatus, and water is charged into the anode chamber to perform electrolysis. The voltage applied between the anode and the cathode is preferably about 5 to 100 V. By this electrodialysis, anions such as organic acids and halogen elements pass through the dialysis membrane and move from the cathode compartment to the anode compartment. In addition, components other than the anion of the water-soluble processing liquid cannot pass through the dialysis membrane and remain in the cathode compartment. Therefore, components required as a water-soluble processing liquid are not lost. In this way,
Anions such as organic acids that lower the pH, anions such as halogen ions and sulfate ions that cause corrosion are removed from the water-soluble working fluid from the water-soluble working fluid. Note that anions accumulate in the water in the anode chamber. For this reason, it is preferable that the anode chamber is periodically replaced with fresh water or that fresh water is continuously circulated.

It is preferred that electrodialysis be performed when the pH of the water-soluble processing liquid has dropped to about 8 to 9. The present invention can take the following forms. The water-soluble working fluid is an alkaline water-soluble working fluid such as a cutting oil, a forging die lubricating oil, and a hydraulic oil.

The above-mentioned anion exchange membrane is a polysulfone-based anion exchange membrane.

[0013]

According to the method for controlling a water-soluble processing liquid of the present invention, a water-soluble processing liquid is supplied to a cathode chamber and water is supplied to an anode chamber to perform electrodialysis, and various salts and acidic components in the water-soluble processing liquid are dialyzed. Through the anode chamber. Thereby, the water-soluble processing liquid can be stably maintained for a long period of time.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the embodiment of the present invention, the apparatus shown in FIG. 1 was used. This device consists of a main tank 1 for working fluid, a filter 2 and an electrodialysis machine.
A tank 3, a catholyte circulation tank 4, the anolyte tank 5, a DC power source 6, the machining fluid present tank 1 catholyte circulation tank 4 sends working fluid through the filter 2 in the catholyte circulation tank 4 from more working fluid from the first pipe system 7 to the tank 1 to return the working fluid, the second piping system back into the cathode chamber 31 to feed the catholyte circulation tank 4 again electrodialysis cell 3 from the machining fluid catholyte circulation tank 4 8 And a third piping system 9 for sending water from the anolyte circulation tank 5 to the anode chamber 32 of the electrodialysis tank 3 and returning it to the anolyte circulation tank 5 again, and supplying water to the anolyte circulation tank 5.
And a fourth piping system 10 for removing waste liquid from the anolyte circulation tank 5.

The electrodialysis tank 3 comprises a cathode chamber 31 and an anode chamber 32 partitioned by a dialysis membrane 33.
A cathode and an anode (not shown) are provided in the anode chamber 32,
These cathode and anode are connected to a DC power supply. Further, a polysulfone-based anion exchange membrane was used as the dialysis membrane 33. The effective surface area of the dialysis membrane 33 is 2.08 dm ² . (Example 1) The apparatus shown in FIG. 1 was used, and a quenching liquid (polyglycol-based) used for heat treatment of a steel material was used for the processing liquid main tank 1.
The first piping system 7 was operated from the processing liquid main tank 1, and 80 liters of the quenching liquid was supplied to the catholyte circulation tank 4 through the filter 2. On the other hand, 6 liters of tap water was supplied to the anolyte circulation tank 5 through the fourth piping system 10. In this state, a DC current of 2 amps was passed between the anode and the cathode while driving the second piping system 8 and the third piping system 9. Electrodialysis was performed for 3 hours in this state.

The pH values of the catholyte circulation tank 4 and the anolyte circulation tank 5 were measured every 20 minutes. Further, water in the anolyte circulation tank 5 was sampled, and the concentration of total acid contained in the water was measured. The obtained results are shown in FIGS. As is clear from FIG. 2, the pH of the quenching solution in the catholyte circulation tank 4 before the electrodialysis was about 8.5, but the pH increased with the passage of time, and the electrodialysis was performed for 3 hours. As a result, the pH of the quenching solution in the catholyte circulation tank increased to about 9.5. The virgin quenching solution not used for quenching had a pH of about 10.0 to 10.5, indicating that the pH was considerably recovered by electrodialysis.

On the other hand, the pH of the water in the anolyte circulation tank 5 is 4.
The pH dropped from about 6 to about 3.2. As shown in FIG. 3, the total acid concentration of this water also increased with the dialysis time, and the total acid concentration increased from about 0.008 to about 0.032. In this water, acetic acid was detected as a main component as an acidic component. Also, slight hydrochloric acid was detected. When the current efficiency was calculated from the detected acidic components, the current efficiency of acid removal was 56%.

(Example 2) An emulsion type cutting fluid used for cutting was used as a water-soluble machining fluid. The cutting fluid is in the range of pH 9.5 to 9.7 in the case of a new fluid, and a chlorine-based extreme pressure additive is used. Since the cutting fluid generates chloride ions due to the oxidation of organic components and the decomposition of the extreme pressure additive with use, the fluid management of the present invention was carried out when the pH dropped to 9.0. The same dialysis apparatus and dialysis membrane as in Example 1 were used. 2 L of the used cutting fluid (used liquid) was supplied to the catholyte circulation tank 4, while 2 L of water was introduced to the anolyte circulation tank 5. The cutting fluid in the catholyte circulation tank 4 was circulated to the cathode chamber 31, and the water in the anolyte circulation tank 5 was circulated to the anode chamber 32. 1A current from DC power supply
Electricity was applied and electrodialysis was performed for 10 hours.

As a result, the cutting fluid in the catholyte circulation tank 4 has pH
Value rises to 9.6, and the pH value of the anolyte circulation tank 5 becomes 2.
To 8. As a result of analyzing and examining the acidic components dialyzed into the anolyte circulation tank 5, a small amount of hydrochloric acid was detected together with carboxylic acids such as acetic acid. Next, the corrosion of the cutting fluid to steel before and after electrodialysis was investigated. The corrosion rate was measured by the polarization resistance method. Use ordinary cast iron for steel 4
cm ² surface area. Table 1 shows the corrosion rates determined from the polarization resistance values. It was confirmed that the corrosion rate of the steel material in the cutting fluid (dialysis fluid) from which chloride ions were removed by electrodialysis was reduced to the same level as that of the new fluid. Further, in the cutting fluid which was continuously used without performing the fluid management of the present invention, the pH of the fluid eventually decreased to 8.0, and a bad smell due to rot was generated.

[0020]

[Table 1] (Example 3) As a water-soluble working fluid, a mold lubricating fluid (natural resin type) used at the time of hot forging of a steel material was used. This lubricating liquid has a pH of about 9.2 in the case of a new liquid, but with use, oxidation of the resin component occurs and the pH decreases. And pH
When the water content is reduced, rot proceeds and a bad smell is generated. Here, the liquid management of the present invention was carried out for a lubricating liquid whose pH had already been reduced to 6.3 and a malodor was generated.

Using the same dialysis apparatus as in Example 1, a porous membrane (made of fluororesin) was incorporated as a dialysis membrane. The effective surface area of one film is 2.08 dm ² . 3 liters of the used lubricating liquid were charged in the catholyte circulation tank, while 3 liters of water were charged in the anolyte circulation tank. Then, the lubricating liquid in the catholyte circulating tank is circulated to the cathode chamber, and the water in the anolyte circulating tank is circulated to the anode chamber, and a current of 1 A is supplied from a DC power supply, and the pH of the lubricating liquid in the catholyte circulating tank is adjusted. The acid component was dialyzed until the pH recovered to 9.2. The electrode used at this time is platinum.

On the way, the pH value of the lubricating fluid is 8.2 and 8.
The liquid was sampled at the time when it rose to 7. After completion of the dialysis, putrefaction odor was reduced in all the dialysis samples. Subsequently, the bacteria count of each sample was measured using Sanicheck (trade name). In addition, each sample was packed in a container and allowed to stand for 2 weeks, and the putrefaction odor was evaluated. Table 2 summarizes the results. Total number of bacteria is 1 in working solution
It was × 10 ⁷ cells / ml or more, but all of the dialysates were reduced to less than 1 × 10 ³ cells / ml. The putrefaction odor after standing was as weak as the dialysis solution at pH 8.7 and 9.2, just like immediately after dialysis. On the other hand, in the dialysate having a pH of 8.2, a strong odor similar to that of the used solution was generated, and it was found that the anaerobic bacteria could not be prevented from growing again.

[0023]

[Table 2]

[0024]

According to the present invention, acidic components and salts which increase with the use of a water-soluble processing liquid can be easily and inexpensively removed, and the pH of the processing liquid can be maintained and controlled to be slightly alkaline. . For this reason, the propagation of bacteria and the like is suppressed, the generation of offensive odor due to decay, the deterioration of the original function of the processing fluid, the corrosion of the processing equipment and the workpiece can be prevented, and the renewal period of the water-soluble processing fluid is greatly reduced. It can be extended.

[Brief description of the drawings]

FIG. 1 is a process diagram of an electrodialysis apparatus used in Examples.

FIG. 2 is a diagram showing the relationship between the electrodialysis time and the pH concentration of the liquid in the catholyte circulation tank and the anolyte circulation tank in Example 1.

FIG. 3 is a diagram showing the relationship between the electrodialysis time and the total acid concentration of the solution in the anolyte circulation tank in Example 1.

[Explanation of symbols]

1: Working fluid main tank 2: Filter 3: Electrodialysis tank 4: Working fluid main tank 5: Filter 6: Electrodialysis tank
7: First piping system 8: Second piping system 9: Third piping system 10: Fourth piping system

Continuing on the front page (72) Inventor Kazutake Takebayashi 1 Toyota Town, Toyota City, Aichi Prefecture Toyota Motor Corporation (72) Inventor Takehiko Nishiguchi 1 Toyota Town Toyota City, Aichi Prefecture Toyota Motor Corporation (56) Reference Document JP-A-63-47370 (JP, A) JP-A-51-51548 (JP, A) JP-A-4-293526 (JP, A) JP-A-1-130783 (JP, A) (58) Field (Int.Cl. ⁷ , DB name) B01D 61/44 500

Claims (3)

(57) [Claims] 1. A water-soluble working fluid is supplied to a cathode chamber of an electrodialysis apparatus in which a porous membrane or an anion exchange membrane is used as a dialysis membrane, and an anode chamber and a cathode chamber are separated by the dialysis membrane. weak Al the pH of the water-soluble working fluid performs a electrodialysis
A liquid management method for a water-soluble processing liquid, comprising maintaining a potash pH. 2. The water-soluble working fluid is an alkaline water-soluble working fluid such as a cutting oil, a forging die lubricating oil, and a hydraulic oil.
The liquid management method of the water-soluble processing liquid described in the above. 3. The method according to claim 1, wherein the anion exchange membrane is a polysulfone-based anion exchange membrane.