JP2003342595A - Oil composition for electro-discharge machining - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an oil composition for electro-discharge machining excellent in machining accuracy, working speed as fundamental performance, suppressing production of tarry substance, excellent in exhausting property of rubbish made in machining, and improving workability and working environment. <P>SOLUTION: The oil composition for electro-discharge machining is obtained by adding (A) a compound having two or more hydroxyphenyl groups and (B) a polymer having kinematic-viscosity ≥30 mm<SP>2</SP>/s at 40≤, ≥10 mm<SP>2</SP>/s at 100°C, and/or a polymer having ≥500 of weight average molecular weight, to a base oil comprising a mineral oil and/or a synthetic oil having a kinematic- viscosity of 0.5-20 mm<SP>2</SP>/s at 40°C. <P>COPYRIGHT: (C)2004,JPO

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electric discharge machining oil composition, and more particularly, to a tar excellent in electric discharge machining, having excellent basic performances such as machining accuracy and machining speed. The present invention relates to an electric discharge machining oil composition capable of suppressing the generation of particulate matter, having excellent discharge properties of machining waste, and improving the working environment. 2. Description of the Related Art In the electric discharge machining method, an electrode (copper, graphite, etc.) and a conductive workpiece are opposed to each other in an insulating medium with a small interval of several to several tens of microns. When a voltage is supplied in a pulsed manner from the machining power supply through this interval, a discharge occurs when the interval between the electrode and the workpiece is the interval at which the discharge starts at that voltage, and the workpiece is machined with high precision. is there. Machining speed (machining efficiency) is a measure of how much the power source's ability can be extracted. Machining accuracy (irregularities of the machining surface, that is, surface roughness, machining surface due to adhesion of burning slag such as oil by electric discharge) This is one of the basic performances in the electric discharge machining method. The electric discharge machining oil used as an insulating medium has a great influence not only on machining accuracy but also on machining speed. For example, Japanese Patent Application Laid-Open No.
No. 7,424, JP-A-62-277220 and JP-A-6-155165 may contain a high molecular weight compound, and JP-A-2-76626 may contain an aromatic compound. Proposed. However, despite these studies, an electric discharge machining oil exhibiting a sufficient machining speed has not yet been obtained. In electric discharge machining, electric discharge is instantaneously performed through electric discharge machining oil, so that the electric discharge machining oil is locally exposed to a high temperature, a part of which is thermally decomposed, and the polycondensation of a pyrolysis product is performed. As a result, a tar-like substance is generated. Tar-like substances are usually removed by a filter, but tar-like substances generated in such a system generally contain fine (1 μm or less) particles, and the demands on filters become very strict. In addition, the equipment becomes complicated and the work becomes complicated. In addition, this tar-like substance not only deteriorates workability, but also causes a reduction in a processing speed due to a locally uneven surface of a machined surface and an unstable discharge caused by adhering to an electrode portion. . Further, the electric discharge machining oil has not only the above-mentioned machining accuracy and machining speed, but also the dischargeability (dispersibility) of machining waste, the odor due to the evaporation of the electric discharge machining oil,
It also affects various other performances such as deterioration of the working environment such as stickiness due to scattering in the machine. The present inventors have proposed an electrical discharge machining oil excellent in various performances as described above (JP-A-2001-115179).
Further improvements are desired. SUMMARY OF THE INVENTION The present invention has been made in view of such circumstances, and has as its object the basic characteristics of excellent processing accuracy and processing speed as well as suppression of the formation of tar-like substances. It is another object of the present invention to provide an electric discharge machining oil composition which is excellent in discharge of machining waste and can improve workability and work environment. The present invention comprises a mineral oil and / or a synthetic oil and has a kinematic viscosity at 40.degree.
(A) a compound having two or more hydroxyphenyl groups in a base oil of 0 mm ² / s, and (B) a kinematic viscosity at 40 ° C. of 30 mm ² / s or more and a kinematic viscosity at 100 ° C. of 1
0 mm ² / s or more polymeric materials, and / or weight-average molecular weight is in the electric discharge machining oil composition comprising 500 or more polymeric materials. BEST MODE FOR CARRYING OUT THE INVENTION As the base oil in the electric discharge machining oil composition of the present invention, mineral oil and / or synthetic oil can be mentioned. The mineral base oil and / or synthetic base oil can be used without any particular limitation as long as it is usually used as a base oil of an electric discharge machining oil. Specific examples of the mineral oil include kerosene fractions obtained by distillation of paraffinic or naphthenic crude oils; normal paraffins obtained by extraction from kerosene fractions; and distillation of paraffinic or naphthenic crude oils. The obtained lubricating oil fraction is purified by appropriately combining at least one of solvent degreasing, solvent extraction, hydrocracking, solvent dewaxing, contact dewaxing, hydrorefining, sulfuric acid washing, and purification treatment such as clay treatment. And the like. Specific examples of the synthetic oil include poly-α-olefins (propylene oligomer, isobutylene oligomer, polybutene, 1-octene oligomer,
1-decene oligomer, ethylene-propylene oligomer, etc.) or hydride thereof, alkylbenzene, alkylnaphthalene, diester (ditridecylglutarate,
Di-2-ethylhexyl adipate, diisodecyl adipate, ditridecyl adipate, di-2-ethylhexyl sebacate, etc., polyol ester (trimethylolpropane caprylate, trimethylolpropaneperargonate, pentaerythritol 2-ethylhexanoate, pentaerythritol Pelargonate, etc.),
Examples include polyglycol, silicone oil, dialkyl diphenyl ether, and polyphenyl ether.
Among these synthetic oils, propylene oligomer hydride, isobutylene oligomer hydride and polybutene hydride are usually called isoparaffins. As the alkylbenzene, any one can be used, but one or two, preferably one, of alkyl groups having 8 to 40 carbon atoms, preferably 8 to 24 carbon atoms.
It is preferable to use those having a plurality. If the alkylbenzene has less than 8 carbon atoms, the volatility may increase. On the other hand, if the alkylbenzene has more than 40 carbon atoms, the required performance may not be obtained. These alkyl groups may be linear or branched, but are preferably branched alkyl groups from the viewpoint of work safety.
As the alkylbenzene to be used, not only an alkylbenzene having a single structure but also a mixture of alkylbenzenes having different structures may be used. In the present invention, the above mineral base oil or synthetic base oil may be used alone, or a mixture of two or more kinds of mineral base oils or a mixture of two or more kinds of synthetic base oils may be used. Alternatively, a mixture of the above-described mineral base oil and synthetic oil base oil may be used. The mixing ratio of the two or more base oils in the mixture is not particularly limited and can be arbitrarily selected. In the present invention, from the viewpoint of working environment such as odor, it is preferable to use a base oil having a saturated content of 95% by volume or more, more preferably a base oil having a saturated content of 98% by volume or more.
It is more preferable to use a base oil having a saturated content of 99% by volume or more, and most preferably to use a base oil having a saturated content of 100% by volume. In addition, the saturated component mentioned here is JIS K25
36 shows the value measured by the fluorescent indicator adsorption method (FIA method) of 36 "Petroleum products-component test method". Specific examples of the base oil having a high saturated content include normal paraffin, isoparaffin and the like. When normal paraffin and / or isoparaffin is used, its content (total content) may be 40% by mass or more based on the total amount of the composition so as not to deteriorate the working environment due to odor and the like. Preferably, more preferably 50% by mass or more, most preferably 60% by mass
That is all. On the other hand, the content is improved to improve the processing speed and processing accuracy (having good surface roughness and no occurrence of stain on the processed surface) and to suppress the formation of tar-like substances. It is preferably at most 99.85% by mass, more preferably at most 99.5% by mass, most preferably at most 99.0% by mass, based on the total amount of the substance. In the present invention, it is preferable to use a naphthenic mineral oil and / or an alkylbenzene in addition to the base oil having a large amount of saturation, since the processing speed and the surface roughness can be further improved. However, when these are used in combination, the occurrence of stains may be accompanied by the occurrence of stains, and among these, it is preferable to use alkylbenzene. Examples of the naphthenic mineral oil include those obtained by appropriately purifying a lubricating oil fraction obtained by distilling the above-described naphthenic mineral oil, and more specifically, those satisfying the following properties are preferable. . Preferably 1) n-d-M analysis by resulting% C _N is 40 or more, more preferably 45 or more, more preferably 50 or more. 2) The aniline point is preferably 70 ° C. or lower;
It is more preferably at most 7 ° C, more preferably at most 65 ° C. 3) The pour point is preferably -30 ° C or lower, and -4
The temperature is more preferably 0 ° C or lower, further preferably -45 ° C or lower. When a naphthenic mineral oil and / or alkylbenzene is used, its content (total content) should be 1% by mass or more based on the total amount of the composition in order to increase the processing speed and obtain good surface roughness. Preferably, more preferably 3% by mass or more, further preferably 5% by mass or more,
Most preferably, it is at least 7% by mass. On the other hand, in order to suppress the occurrence of stains, the content is based on the total amount of the composition,
It is preferably at most 50% by mass, more preferably at most 40% by mass, most preferably at most 30% by mass. As described above, as the base oil used in the present invention, normal paraffin and / or isoparaffin are preferably used because the working environment such as odor can be further improved, and the processing speed and surface roughness can be improved. Therefore, it is preferable to use naphthenic mineral oil and / or alkylbenzene. Therefore, in the present invention, it is more preferable to use a combination of normal paraffin and / or isoparaffin and a naphthenic mineral oil and / or alkylbenzene so as to satisfy all of the above-mentioned performances, and the occurrence of stains is less likely to occur. Therefore, it is more preferable to use a combination of normal paraffin and / or isoparaffin and alkylbenzene. The total content of naphthenic mineral oil and / or alkylbenzene with respect to the total content of normal paraffins and / or isoparaffins is preferably 1 with respect to the former content of 1 in order to improve processing speed and surface roughness. It is 0.05 or more, more preferably 0.1 or more.
On the other hand, the content is preferably 0.5 or less, more preferably 0.4 or less, in order to suppress the occurrence of stains. The base used in the present invention is preferably 4 in the case of using one kind of base oil alone or in the case of using a mixture of two or more kinds of base oils, from the viewpoint of fire safety.
The kinematic viscosity at 0 ° C. is not less than 0.5 mm ² / s, while the kinematic viscosity at 40 ° C. is not more than 20 mm ² / s in order to eliminate the processing debris and maintain the cooling action of the electrodes and the like. To ensure more fire safety,
The kinematic viscosity at 40 ° C. is preferably 1 mm ² / s
The above is more preferably 1.5 mm ² / s or more. On the other hand, removal of processing dust is easy, stains are less likely to occur, the cooling action of electrodes and the like is good, and the processing speed is improved. In order to obtain better effects such as
The kinematic viscosity at 0 ° C. is preferably 15 mm ² / s or less, more preferably 10 mm ² / s or less, further preferably 5 mm ² / s or less, and most preferably 3 mm ² / s or less. When two or more base oils are used in combination, the lower limit of the kinematic viscosity at 40 ° C. of each base oil is preferably 0.5 mm ² / s or more from the viewpoint of fire safety. More preferably, it is at least 1 mm ² / s, more preferably at least 1.5 mm ² / s. On the other hand, it is easy to remove processing dust, hardly causes stains, and has a good cooling action of electrodes and the like. In order to obtain more excellent effects such as a certain and improved processing speed, the upper limit of the kinematic viscosity at 40 ° C. of each base oil is preferably 20 mm ² / s or less, more preferably 15 mm ² / s. Or less, more preferably 10 mm ² / s or less, still more preferably 5 mm ² / s or less, and most preferably 3 mm ² / s or less. The content of the base oil is 40% based on the total amount of the composition.
% By mass or more, more preferably 50% by mass or more.
% By mass, more preferably 60% by mass or more, and most preferably 70% by mass or more. On the other hand, the content of the base oil is preferably not more than 99.85% by mass, more preferably not more than 99.85% by mass, based on the total amount of the composition, in order to facilitate removal of processing waste and tar-like substances staying between the poles. 99.5% by mass
Or less, most preferably 99.0% by mass or less. The compound (A) having two or more hydroxyphenyl groups used in the present invention is a compound having two or more hydroxyphenyl groups in a molecule, and each hydroxyphenyl group has 1 to 1 carbon atoms. 4 may be substituted with an alkyl group. The compound having two or more hydroxyphenyl groups used in the present invention is preferably a compound having at least one alkyl group in each hydroxyphenyl group, and more preferably a compound having two or more hydroxyphenyl groups. The compound used in the present invention may be a compound having three or more hydroxyphenyl groups, but is preferably a compound having two hydroxyphenyl groups because the formation of tar-like substances can be further suppressed. A plurality of hydroxyphenyl groups may be directly bonded to each other, or may be bonded via a hydrocarbon group, or may be bonded via a bonding group containing an atom other than carbon and hydrogen such as oxygen and sulfur. May be combined. As the bonding group containing oxygen and / or sulfur,-
S-, -OC (= O)-, and a combination thereof with a hydrocarbon group are exemplified. Among these bonding groups, a group containing oxygen, a group containing sulfur, or a group containing oxygen and sulfur is preferable because a generation of a tar-like substance can be further suppressed, and a group containing oxygen and sulfur is preferable. Is more preferred. The hydroxyphenyl group used in the present invention is 2
The compound having at least one compound is preferably a bisphenol compound represented by the following general formula (1). Embedded image In the general formula (1), R ¹ , R ² , R ³ and R ⁴ each independently represent an alkyl group having 1 to 4 carbon atoms, and R ⁵ , R ⁶ , R ⁷ and R ⁸ are Each of them represents an alkylene group having 1 to 10 carbon atoms. The alkyl group represented by R ^{1 to} R ⁴ may be linear or branched, and specific examples thereof include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, Isobutyl group, s
Examples thereof include an ec-butyl group and a tert-butyl group. Of these, a tert-butyl group is preferred from the viewpoint of excellent suppression of tar-like substances. The alkylene group represented by R ^{5 to} R ⁸ is
It may be linear or branched, and as specific examples thereof,
Methylene group, ethylene group, propylene group, butylene group,
Examples thereof include alkylene groups such as a pentylene group, a hexylene group, a heptylene group, an octylene group, a nonylene group, and a decylene group (these alkylene groups may be linear or branched). Among these, a methylene group and an ethylene group (dimethylene group, methylmethylene group) are preferable. Preferred specific examples of the compound having two or more hydroxyphenyl groups used in the present invention are shown below. Embedded image The hydroxyphenyl group used in the present invention is 2
The content of the compound having at least one compound is arbitrary, but is usually 0.05% by mass or more, preferably 0.1% by mass or more based on the total amount of the composition. On the other hand, the content is usually 10% by mass or less, preferably 5% by mass or less based on the total amount of the composition. When the content of the compound is less than 0.05% by mass based on the total amount of the composition, the effect of suppressing the formation of tar-like substances during electric discharge machining is poor, while the content is 10% by mass based on the total amount of the composition. In the case where it exceeds, the consumption of the electrode becomes large, so that each is not preferable. 4 used as the component (B) of the present invention
Examples of a polymer substance having a kinematic viscosity at 0 ° C. of 30 mm ² / s or more and a kinematic viscosity at 100 ° C. of 10 mm ² / s or more and / or a polymer substance having a weight average molecular weight of 500 or more include, for example, And high-viscosity oils, polymers (polymers), and resins having the formula: Examples of the polymer substance having the above kinematic viscosity include mineral oil from which the kerosene fraction and the normal paraffin component have been removed from the aforementioned base oils. Specifically, for example, a lubricating oil fraction obtained by distillation of a paraffinic or naphthenic crude oil is subjected to solvent removal, solvent extraction, hydrocracking, solvent dewaxing, catalytic dewaxing, hydrorefining, sulfuric acid washing. And those obtained by appropriately combining one or more purification treatments such as clay treatment. Examples of the polymer (polymer) include poly-α-olefins (eg, polybutene, polyisobutylene, etc.) or hydrides thereof, polyamide compounds, polyalkylstyrene, polyvinyl acetate, polyalkyl (meth) acrylate, Examples include an ethylene-propylene copolymer or a hydride thereof, and a styrene-maleic anhydride copolymer. Examples of the resin include a terpene resin and a petroleum resin. Examples of the terpene resin include hemiterpenes, monoterpenes such as dipentene, sesquiterpenes, diterpenes, sesterterpenes,
Examples thereof include polymers of triterpenes, tetraterpenes, and polyterpenes, hydrides thereof, and modified resins thereof. As the petroleum resin, for example, among the cracked fractions of petroleum, a resin derived from a hydrocarbon fraction having 4 or 5 carbon atoms, a hydrocarbon fraction having 9 or 10 carbon atoms, or a fraction thereof Resin as mixed raw material,
Alternatively, these modified resins, cyclopentadiene-dicyclopentadiene copolymerized petroleum resins, hydrides thereof, and modified resins thereof can be exemplified. The component (B) of the present invention includes processing accuracy,
In addition, since the processing speed can be further increased, and an excellent effect in improving workability due to stickiness and the like can be obtained in a well-balanced manner, a polymer (polymer) is preferable, and a poly-α-olefin (for example, Polybutene, polyisobutylene, etc.), ethylene-propylene copolymer, polymethacrylate, or a hydride thereof is more preferable, and polybutene or a hydride thereof is more preferable. In addition, polybutene or its hydride is also preferable from the viewpoint that stain is hardly generated. The polymer substance (B) used in the present invention has a kinematic viscosity at 40 ° C. of preferably 100 mm ² in order to further improve processing accuracy and processing speed.
/ S, more preferably at least 500 mm ² / s, still more preferably at least 1000 mm ² / s, most preferably at least 5000 mm ² / s, and 10
The kinematic viscosity at 0 ° C. is preferably 100 mm ² / s or more, more preferably 500 mm ² / s or more, and most preferably 1000 mm ² / s or more. On the other hand, the upper limit of the kinematic viscosity at 40 ° C and 100 ° C is not particularly limited, but the kinematic viscosity at 40 ° C is usually 250,000.
mm ² / s or less, and in order not to cause deterioration of the working environment such as stickiness, preferably 200,000 mm ² / s
Or less, more preferably 180,000 mm ² / s
It is as follows. For the same reason, the kinematic viscosity at 100 ° C. is not more than 10000 mm ² / s, preferably not more than 7000 mm ² / s, more preferably, 50
00 mm ² / s or less. The polymer used as the component (B) in the present invention has a weight average molecular weight of preferably 1,000 or more, more preferably 2,000 or more, in order to obtain more excellent processing accuracy and processing speed. It is preferably one having 3,000 or more, most preferably 5,000 or more. On the other hand, the upper limit of the weight average molecular weight is
Although not particularly limited, it is usually 50,000 or less, preferably 40,000 or less, more preferably 30,000 or less, and most preferably 10,000 or less. The content of the high molecular substance as the component (B) used in the present invention is preferably at least 0.1% by mass, more preferably at least 0.3% by mass, and still more preferably, based on the total amount of the composition. Is 0.5% by mass or more, most preferably 1% by mass or more. On the other hand, the content is preferably 30% by mass or less based on the total amount of the composition, and more preferably 20% by mass.
% By mass, most preferably 15% by mass or less.
When the content of the component (B) is less than 0.1% by mass based on the total amount of the composition, it is difficult to obtain a sufficient processing speed and good processing accuracy, while the content is lower than the total amount of the composition. When the content exceeds 30% by mass, workability such as stickiness is deteriorated, and the generation of tar-like substances tends to increase, which is not preferable. The electric discharge machining oil composition of the present invention may contain a known additive, if necessary, for the purpose of further improving the performance as the electric discharge machining oil composition. Specific examples of the additive include an antioxidant, an antifoaming agent, a rust inhibitor, a metal deactivator, an oil agent, an extreme pressure agent, a detergent / dispersant, and a surfactant. The content of these additives is usually 0.005 to 10% by mass based on the total amount of the electric discharge machining oil composition. EXAMPLES The present invention will be described in more detail with reference to the following Examples and Comparative Examples, but the present invention is not limited thereto. (Examples 1 to 10 and Comparative Examples 1 and 2)
The electric discharge machining oil composition of the present invention according to (Examples 1 to 10)
And a discharge machining oil composition (Comparative Examples 1 and 2) for comparison, respectively. Using the obtained electric discharge machining oil composition (oil agent), an electric discharge machine with servo (Diax EA12E,
Using Mitsubishi Electric Corporation), imposition processing was performed under the following processing conditions. And the performance with respect to the processing oil composition was evaluated by the following evaluation methods (1) to (3). Also, (4) a stickiness test was performed to evaluate the degree of stickiness of the oil agent. Table 2 shows the evaluation results. (Processing conditions) Electrode: Copper square bar electrode (5 mm x 5 mm) Work: SKD-61 material (5 cm x 5 cm x 1 cm) Reduction allowance (clearance): 0.10 mm Processing conditions: Processing consisting of 7 steps in Table 1 Was. In addition,
When the penetration depth of the electrode reached a predetermined value, the process proceeded to the next step. Working fluid: The working tank was filled with 12 L of the working oil composition. [Table 1] (1) Evaluation of processing speed The time required for the processing (the time until the electrode penetration depth reaches a predetermined position) and the weight change of the work before and after the processing are measured, and the processing speed is calculated using the following equation. Calculated. Processing speed (mg / min) = Weight change of work before and after processing (mg) / Time required for processing (min) (2) Evaluation of surface roughness The surface roughness (Rmax) was measured using a roughness profile measuring device (Surfcom 590A, manufactured by Tokyo Seimitsu Co., Ltd.). (3) Evaluation of tar generation After the above-mentioned processing speed test, the state of tar adhesion to the electrode and the state of tar adhesion to the wall surface and the bottom surface of the processing tank were visually observed. (4) Stickiness test Put 5 mL of oil agent as a sample on an aluminum dish (100 mm x 70 mm),
After standing for a period of time, the degree of stickiness of the sample-attached portion was judged by finger touch. [Table 2] From the results shown in Table 2, when the electric discharge machining oil compositions of the present invention (Examples 1 to 10) were used, all showed excellent machining speeds and good surface conditions after machining. Further, it can be seen that no or little stain is generated on the processed surface, and further, the formation of tar-like substances and stickiness hardly occur. On the other hand, when a composition containing no component (A) is used (Comparative Example 1), a tar-like substance is generated, and when a composition containing no component (B) is used (Comparative Example 2), It can be seen that a sufficient processing speed cannot be obtained. By using the electric discharge machining oil composition of the present invention, excellent machining accuracy (good surface condition, suppression of occurrence of stain on the machined surface) and machining speed can be obtained. ,
Efficient electric discharge machining can be performed efficiently, and a highly accurate machining surface with few surface irregularities and almost no stain can be obtained. In addition, since the generation of tar-like substances is also suppressed, there is no unstable discharge due to adhesion to the electrode portion, and a reduction in the processing speed due to this can be avoided. Further, the workability and work environment can be further improved because the discharge property of the processing waste is good and the odor due to evaporation and the stickiness due to scattering in the processing machine can be reduced.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI theme coat ゛ (Reference) C10M 105/36 C10M 105/36 105/38 105/38 107/02 107/02 107/50 107/50 129 / 10 129/10 129/76 129/76 135/26 135/26 143/04 143/04 143/06 143/06 143/10 143/10 143/12 143/12 143/16 143/16 145/08 145/08 145/14 145/14 145/16 145/16 149/18 149/18 159/04 159/04 // C10N 20:02 C10N 20:02 20:04 20:04 30:00 30:00 Z 40:16 40:16 (72) Inventor Osamu Hasegawa 2-1-1, Ryugashima, Niigata City, Niigata Japan F-term within Petroleum Processing Co., Ltd. 3C059 AA01 AB00 EA03 EA09 4H104 BA04A BB05C BB33A BB35C BB41A BG14C CA01A CA01C CA07C CA08C CA12C CB04C CB08C CB09C CE13C CJ02A DA02A DA02C EA02A EA02C EA03C LA20 PA22

Claims (1)

Claims 1. It is composed of mineral oil and / or synthetic oil and has a temperature of 40 ° C.
Base oil having a kinematic viscosity of 0.5 to ²⁰ mm ² / s,
(A) a compound having two or more hydroxyphenyl groups,
And (B) a polymer substance having a kinematic viscosity at 40 ° C. of 30 mm ² / s or more and a kinematic viscosity at 100 ° C. of 10 mm ² / s or more, and / or a polymer substance having a weight average molecular weight of 500 or more. Electric discharge machining oil composition.