JPH0586385A - Nonflammable fluid for electric discharge machining - Google Patents

Abstract

PURPOSE:To attain a marked improvement in the machining rate of the subject fluid and minimize the formation of tarry substances at the time of electric discharge machining for improvement of machining efficiency by using 3- mercapto-1,2-propanediol. CONSTITUTION:The objective fluid comprises a nonflammable base fluid for electric discharge machining and 3-mercapto-1,2-propanediol added thereto.

Description

Detailed Description of the Invention

[0001]

The present invention relates to 3-mercapto-1,
The present invention relates to a non-flammable electric discharge machining fluid in which the processing speed is greatly improved by adding 2-propanediol, and the generation of tar-like substances during electric discharge machining is reduced to improve the machining efficiency.

[0002]

2. Description of the Related Art In the electrical discharge machining method, an insulating medium (aqueous electrical discharge machining fluid or oily electrical discharge machining fluid) is filled between an electrode and a conductive workpiece, and the electrode and the workpiece are interrupted. It is a method of discharging and performing high-precision processing (cutting, digging or cutting, etc.) of the work piece. In electrical discharge machining, the surface temperature of the work piece becomes high (for example, thousands of degrees), and industrial practice is often carried out by continuous operation in an unmanned factory. It is desired to use an aqueous electric discharge machining fluid which is a non-flammable electric discharge machining fluid. However, although the machining speed of the aqueous electric discharge machining liquid is generally higher than that of the oil-based electric discharge machining liquid, it is insufficient from the viewpoint of productivity because the electrode is consumed a lot. Moreover, it is known that the electric discharge machining fluid has a low machining efficiency because, for example, the tar-like substance generated during electric discharge machining causes arc discharge or the like to make it impossible to perform electric discharge machining. That is, generated substances (particularly tar-like substances) are generated by direct or indirect change (for example, chemical change) by the discharge energy, and these are dissolved and mixed in the aqueous electric discharge machining fluid, and coloring and generation of the machining fluid. Since arc discharge between electrodes due to adhesion of substances to the work piece, change in shape of the work piece, electric discharge machining impossible due to deterioration of insulation etc.
It is known that the machining efficiency of the aqueous electric discharge machining fluid is low.
In particular, when a tar-like substance is generated in the aqueous electric discharge machining liquid exposed to high temperature between the electrode and the workpiece during electric discharge machining, there is a problem that it easily falls into arc discharge. .. Then, in order to prevent a decrease in machining efficiency, the discharged electrical discharge machining fluid is filtered and treated with an ion exchange resin to remove the substances produced by the electrical discharge machining and clean it, and the machining fluid is circulated again. Although I try to use it, if there are many tar-like substances, the capture capacity of the ion exchange resin will reach the usage limit in a short time, and even if it is treated with the ion exchange resin, the aqueous EDM solution must be replaced frequently. I will not get it. On the other hand, there are cases where the factors of the aqueous electric discharge machining fluid that control the machining speed and the generation mechanism of the tar-like substance generated by electric discharge machining are substantially unknown, and thus the machining speed and machining efficiency of the aqueous electric discharge machining fluid are improved. The fact is that there is no effective proposal, even though many of the studies have been conducted from a chemical, electrical and mechanical standpoint.

[0003]

SUMMARY OF THE INVENTION It is an object of the present invention to obtain a non-flammable electric discharge machining fluid which has a significantly high machining speed and reduces the generation of tar-like substances in electric discharge machining to improve machining efficiency. To do.

[0004]

The non-combustible electric discharge machining fluid according to the present invention is characterized by comprising 3-mercapto-1,2-propanediol in a non-combustible electric discharge machining base fluid. It is a thing.

DETAILED DESCRIPTION OF THE INVENTION A large number of known and novel water-soluble organic compounds are added to a base liquid for electric discharge machining,
As a result of studying the effect of them on the machining fluid, especially the addition of 3-mercapto-1,2-propanediol significantly increased the machining speed of the non-combustible electric discharge machining fluid, and the amount of tar-like substances generated during electric discharge machining. It has been found that the processing efficiency is improved by significantly reducing the above.

<Non-flammable electric discharge machining liquid> The non-flammable electric discharge machining liquid according to the present invention comprises 3-mercapto-1,2-propanediol in a non-flammable base liquid. 3-
The addition amount (content) of mercapto-1,2-propanediol may be small. The content is 0.1 to 5.0% by weight (based on the weight of the base liquid of the nonflammable electric discharge machining liquid), and particularly preferably 1% by weight. The addition effect clearly appears at 0.1% by weight or more, and even if it exceeds 5.0% by weight, the addition effect does not increase so much. The 3-mercapto-1,2-propanediol in the non-flammable electric discharge machining liquid is typically dissolved in the base liquid, but it may be contained in a dispersed state in some cases.

<Base Liquid> The base liquid of the non-flammable electric discharge machining liquid according to the present invention is a non-flammable electric discharge machining liquid containing water. Therefore, any base liquid used for the aqueous electric discharge machining liquid can be used regardless of the type of the additive substance of the base liquid. The base liquid of the aqueous electric discharge machining liquid is composed of water and a water-soluble organic polymer, etc., but is prepared by adding an additive substance to water so as to be suitable for a predetermined electric discharge machining (for example, engraving or digging). Many things are also used. The additive substance is added in order to make the aqueous electric discharge machining liquid suitable for electric discharge machining in terms of density, electric conductivity, viscosity, pour point and the like. In some cases, a larger amount of additive substance than water may be added, but a small amount of such water may be the base liquid. In addition, if the base liquid is in a range capable of retaining nonflammability due to water,
Oil may be included. In that case, the base liquid is water or a continuous phase of oil in which oil or water is dispersed. Therefore, if the base liquid is nonflammable because it contains water, 3-mercapto-1,2-propanediol can be added to improve both processing speed and processing efficiency. In the description, the machining fluid is a non-flammable discharge machining fluid in the sense that it is a non-flammable base fluid machining fluid. Then, in a base solution in which a water-soluble organic polymer is dissolved in water as an additive substance, even when the amount of the polymer in the base solution is small or large,
By adding mercaptopropanediol to the base liquid, the processing speed of the processing liquid is increased, the amount of tar-like substances produced in the processing liquid is significantly reduced, and the processing efficiency is improved. The water-soluble organic polymer is an organic polymer having a water-soluble group in the molecule, and the water-soluble group has, for example, a group having a strong interaction with water such as a hydroxyl group and / or an ether group. Is. Examples of the water-soluble organic polymer include polyethylene glycol and its derivatives, polypropylene glycol and its derivatives, and a copolymer of ethylene oxide and propylene oxide.

<Use of Nonflammable Electric Discharge Machining> The use of the nonflammable electric discharge machining fluid of the present invention is also not limited, and the electric discharge machining can be performed by the same method of use as a normal aqueous electric discharge machining fluid. .. A typical method of using an aqueous electric discharge machining liquid is to clean the electric discharge machining by processing the electric discharge machining liquid by filtration and an ion exchange resin, and circulate and reuse. However, any other cleaning means may be provided in the path for circulating and reusing the processing liquid. However, when the non-combustible electric discharge machining fluid of the present invention is used, the amount of tar-like substances produced during electric discharge machining is significantly reduced.
Arc discharge does not occur, and the processing efficiency of the ion-exchange resin until the capping ability of the tar-like substance reaches its limit is greatly increased, thereby significantly improving the processing efficiency. The following examples serve to illustrate the invention in more detail. They are shown for illustrative purposes and do not limit the invention in any way.

[0009]

Examples Non-flammable electric discharge machining liquid Table 1 below shows the physical properties of the base liquid of the non-flammable machining liquid used in this example. This base solution is aqueous and is commercially available under the name of Baytle QL-50. Table 1 Density (g / cm ³ 25 ° C.) 1.07 Electrical conductivity (μs / cm ² ) 3.3 Kinematic viscosity (cS st 40 ° C.) 5.7 PH 5.8 Pour point (° C.) -22

Experimental Apparatus Table 2 below shows the specifications of the experimental apparatus used in this example. Table 2 Electric Discharge Machine SODIC H 3 Workpiece SKD-61 Machining depth 10mm Machining electrode Graphite ED-3 50 × 50mm square

Discharge conditions Table 3 below shows the discharge conditions. Table 3 ) Current 90 A (during short circuit) τon 140 to 550 μs τoff 14 to 60 μs

Experimental Method Processing Tank As shown in the side sectional view of FIG. 1, a processing electrode (2) is placed on the bottom of the processing tank (1), and a workpiece (3) is placed on it with a predetermined gap. The (SKD-61) is provided in such a state that it can be controlled and moved. The gap between the machining electrode (2) and the workpiece (3) is the machining tank (1).
It is insulated by the working fluid (4) that fills the inside and discharges there.

Circulation route of the working fluid The working fluid (4) is sent from the working tank (1) to a filtering device (diatomaceous earth is used as a filter material) (not shown), and mixed therewith in the working fluid (4) by electric discharge machining. Large metal powder is removed by filtration. The filtered working liquid (4) is passed through an ion exchange resin tower (not shown), and tar-like substances that have not been removed by filtration are captured by the ion exchange resin. The cleaned machining fluid (4) is sent to a machining fluid cooling device (not shown) via a temporary storage tank (not shown) to be cooled to a predetermined temperature and returned to the machining tank (1). Used for electrical discharge machining again.

Experimental Results FIG. 2 below is a graph showing the relationship between τon and the processing speed obtained in this experiment. In FIG. 2, 3-mercapto-1,2-propanediol is abbreviated as MDP. And according to FIG. 2, 3-mercapto-1,2-
The processing speed of the non-flammable processing liquid containing propanediol was improved by 15 to 20%, and the improved processing speed was maintained under a wide range of processing conditions. Moreover, it was confirmed that the tar-like substance was extremely rarely produced on the work piece.

[0015]

According to the present invention, 3-mercapto-1,2
-The machining speed can be greatly increased simply by adding propanediol to the non-flammable electric discharge machining fluid. Moreover, the amount of tar-like substances produced during electric discharge machining is extremely small, and the electric discharge machining efficiency is improved.

[Brief description of drawings]

FIG. 1 is a schematic view of a processing tank.

FIG. 2 is a graph showing a relationship between τon as an experimental result and a processing speed.

[Explanation of symbols]

 1 Processing Tank 2 Processing Electrode 3 Workpiece 4 Processing Liquid

Claims (2)

[Claims] 1. A non-combustible electric discharge machining fluid, which comprises 3-mercapto-1,2-propanediol in a non-combustible electric discharge machining base fluid. 2. The content of 3-mercapto-1,2-propanediol is 0.1 to 5.0% by weight.
The non-flammable electric discharge machining fluid described in.