JPH0683930B2 - EDM liquid - Google Patents

Description

Description: FIELD OF THE INVENTION The present invention relates to a non-combustible electric discharge machining fluid, and more particularly to a non-combustible electric discharge machining fluid that does not generate a bad odor due to a decomposed gas of the non-combustible electric discharge machining fluid generated during electric discharge machining. .

[Background of the Invention]

Conventionally, an aqueous solution of polyethylene glycol or a polyhydric alcohol has been proposed as a non-flammable electric discharge machining fluid instead of a flammable mineral oil-based electric discharge machining fluid. However, these nonflammable electric discharge machining liquids produce a bad odor due to the gas decomposed and produced from the nonflammable electric discharge machining liquid during machining. Therefore, when the above-mentioned non-flammable electric discharge machining liquid is used, there is a problem that machining cannot be performed unless a local exhaust device is installed, unlike the case where a conventional mineral oil-based electric discharge machining liquid is used.

In addition, non-combustible electrical discharge machining liquids that do not produce a foul odor when decomposed by the non-combustible electrical discharge machining liquid generated during electrical discharge machining
There is a problem that the electrical discharge machining characteristics are poor and it cannot be used in practice.

〔The invention's effect〕

It is an object of the present invention to provide a non-flammable electric discharge machining liquid which eliminates the above-mentioned problems of the prior art, has good electric discharge machining characteristics, and does not generate a bad odor during electric discharge machining.

[Outline of Invention]

In order to achieve the above-mentioned object, the inventor has conducted various studies on non-combustible electric discharge machining liquid, and found that a polyoxyalkylene alkyl ether solution is preferable. The polyoxyalkylene alkyl ether has the following general formula (1)
In those shown well RO (R'O) nOH ...... (1) where the above general formula (1), R is _{C 12 H 25 -, C 13} H 27 -, C
₁₄ H ₂₉ −, C ₁₅ H ₃₁ −, and R ′ is —CH ₂ CH ₂ —, —CH ₂ CH.
_{2 CH 2 -, - CH 2} CH 2 CH 2 CH 2 - and it is, n represents an 14 to 18. ) Among these R is C ₁₂ H ₂₅ -, R 'is -CH ₂ CH ₂ -, polyoxyethylene lauryl ether n is 17 (molecular formula C ₁₂ H ₂₅ O-
_{(CH 2 CH 2 O) 17} -OH) are preferred.

The polyoxyalkylene alkyl ether aqueous solution is preferably a solution containing 10 to 30% by weight of polyoxyalkylene alkyl ether, and 15 to 30% by weight.
Solutions are more preferred, with 20% by weight solutions being most preferred.

Further, the above polyoxyalkyl ether aqueous solution may be blended with a silicone antifoaming agent, and the blending ratio is 1 to 0.01 weight% of the silicone antifoaming agent with respect to 99 to 99.99% by weight of the polyoxyalkylene alkyl ether aqueous solution. %, Preferably 99.5 to 99.95% by weight of polyoxyalkylene alkyl ether aqueous solution, 0.5 to 0.
It is 05% by weight.

Examples of the silicone-based defoaming agent include dimethyl polysiloxane To use. This chemical compound is preferably used by adding it to a polyoxyalkylene glycol derivative.

Example of Invention

 Hereinafter, the present invention will be described in detail with reference to examples.

Example _{1 C 12 H 25 O- (CH} 2 CH 2 O) 17 -OH5g, 10g, 15g, 20g, 30g,
35g and pure water 95g, 90g, 85g, 80g, 70g with conductivity of 10μS / cm,
65g is mixed with a non-combustible electric discharge machining solution of 5% by weight, 15% by weight, 20% by weight, 30% by weight and 35% by weight of C ₁₂ H ₂₅ O- (CH ₂ CH ₂ O) ₁₇ -OH. Created.

Then, in the above 6 kinds of electric discharge machining liquids, graphite electrodes (diameter 25 mm) were used as electrodes, and electric discharge machining of SKD1 was performed with a discharge peak current of 52 A and an applied pulse width of 1000 μS. Then, the machining speed, the electrode wear rate, and the machined surface roughness were obtained, and it was examined whether or not the odor of the gas decomposed by the electric discharge machining was nonflammable.

The measurement results are as shown in Table 1, and it was found that good characteristics were exhibited in the range of 10 to 30% by weight.

Example 2 An electric discharge machining experiment of SKD1 was carried out in a 20% by weight aqueous solution of polyoxyethylene lauryl ether using a graphite electrode (diameter 25 mm) with a discharge peak current of 52 A and an applied pulse width of 30 to 1000 μS.

Also, for comparison, mineral oil-based electric discharge machining oil and conductivity 10 μS 1 cm
The electric discharge machining was performed under the same conditions as above, using 80% by weight of pure water.

FIG. 1 shows the relationship between the processing speed and the pulse width. The electric discharge machining speed 3 of pure water is 50 which is the electric discharge machining speed 2 of mineral oil type electric discharge machining oil.
%, The electric discharge machining speed 1 of the electric discharge machining fluid of the present invention is 160 to 260% of that of the mineral oil type electric discharge machining oil in the region where the pulse width is 100 μS or more. FIG. 2 shows the relationship between the electrode wear rate (volume wear ratio) and the pulse width. The electrode wear rate 6 of pure water indicates that processing with a wear rate of 15% or less is impossible. On the other hand, the electrode wear rate 4 of the electric discharge machining fluid of the present invention realizes a machining of about 1% or less, which is close to the electrode wear rate 5 of the mineral oil type electric discharge machine oil in the region of the pulse width of 100 μS or more.

The surface roughness of the workpiece when the electric discharge machining fluid of the present invention was used was equivalent to the surface roughness due to the electric discharge machining oil.

FIG. 3 and FIG. 4 show the relationship between the concentration of polyoxyethylene lauryl ether and the processing performance. The polyoxyethylene lauryl ether concentration was 0 to 30% by weight. At a concentration of 30% by weight or more, the viscosity becomes high and processing is impossible. Fig. 3 shows a peak current of 52A and a pulse width of 1000.
It is the relationship between the processing speed and the polyoxyethylene lauryl ether aqueous solution concentration when processing with μS. The processing speed increases remarkably up to a concentration of 10% by weight, and the processing speed is saturated at a concentration of 10% by weight or more. On the other hand, as for the electrode wear rate, as shown in FIG. 4, the performance is such that the wear rate is 5% or less when the concentration is 10 wt% or more, and the wear rate is 1% or less when the concentration is 15 wt% or more.

Also, during processing, a large amount of bubbles were generated on the surface of the processing liquid,
By adding 0.01 to 1% by weight of dimethylpolysiloxane as an antifoaming agent, foaming could be suppressed without changing the processing characteristics.

Comparative Example Using a conventionally proposed aqueous solution of 30% by weight of an ethylene glycol aqueous solution, processing was carried out under the same processing conditions as above with a peak current of 52 A and a pulse width of 1000 μS. As a result, the processing speed was 120 mm ³ / min and the electrode wear rate was 7.7.
%, The processed surface roughness was 75 μm Rmax.

Compared with the processing characteristics of the polyoxyethylene lauryl ether aqueous solution, the processed surface roughness is excellent, but the processing speed and electrode wear rate are considerably inferior, and the polyoxyethylene lauryl ether aqueous solution is excellent overall.
In addition, processing with an ethylene glycol aqueous solution gives a strong aldehyde odor, which significantly deteriorates the working environment.

〔The invention's effect〕

As described above, according to the nonflammable electric discharge machining liquid of the present invention, it is possible to perform electric discharge machining with a low electrode consumption rate without generating an unpleasant odor.

[Brief description of drawings]

Fig. 1 shows the relationship between the machining speed and pulse width of various EDMs, Fig. 2 shows the relationship between the electrode wear rate and pulse width of various EDMs, and Fig. 3 shows the relationship between the EDM concentration and machining speed. Figure,
FIG. 4 is a diagram showing the relationship between the electric discharge machining liquid concentration and the electrode wear rate. 1 ... EDM speed of EDM of the present invention 2 ... EDM speed of mineral oil-based EDM oil 3 ... EDM speed of pure water 4 ... Electrode wear rate of EDM of the present invention 5 ... Electrode wear rate of mineral oil-based electric discharge machining oil 6 ... Electrode wear rate of pure water

Claims (6)

[Claims] 1. An electric discharge machining fluid comprising a polyoxyalkylene alkyl ether represented by the general formula RO (R'O) nOH (where R is an alkyl group and R'is an alkylene group) and water. 2. R is a lauryl group (C ₁₂ H ₂₅ —),
_2. The electric discharge machining fluid according to claim 1, wherein R ′ is —CH ₂ CH ₂ — and n is polyoxyethylene lauryl ether. 3. The electric discharge machining fluid according to claim 2, wherein the concentration of the polyoxyalkylene alkyl ether is 10 to 30% by weight. 4. A polyoxyalkylene alkyl ether represented by the general formula RO (R′O) nOH (where R is an alkyl group and R ′ is an alkylene group), water, and a silicone antifoaming agent. A characteristic EDM fluid. 5. The electric discharge machining fluid according to claim 4, wherein the silicone antifoaming agent is 0.01 to 1% by weight. 6. The electric discharge machining fluid according to claim 4, wherein the silicone antifoaming agent is dimethylpolysiloxane.