JP2000230616A - Ball screw - Google Patents

Abstract

PROBLEM TO BE SOLVED: To extend the lubricating life by lubricating a ball screw with a grease to which at least one compound selected from organic nickel compound and organic tellurium compound is blended. SOLUTION: This ball screw is lubricated with a grease based on mineral oil, synthetic oil, or mixed oil to which at least one compound selected from organic nickel compound and organic tellurium compound with nickel or tellurium as metal source using a metal salt compound, coordination compound, additive compound, alkyl metal compound, metal acid ester, and metal alkoxide compound of an organic acid as organic carboxylic acid compound, organic sulfur acid compound or organic phosphoric acid is blended. According to this, since the grease feeding interval can be extended without damaging the ball screw raceway, the lubricating life can be extended.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a ball screw,
More specifically, the present invention relates to, for example, a ball screw for high load use incorporated in an injection drive shaft of an electric injection molding machine, a driving mechanism of a mold clamping mechanism, or an electric press or a bender.

[0002]

2. Description of the Related Art Conventionally, an injection drive shaft of an injection molding machine and a drive unit of a mold clamping mechanism are generally driven by a hydraulic cylinder. However, due to environmental problems, the drive by a combination of an electric motor and a ball screw is performed. It is increasing. FIG. 1 shows an example of a ball screw. A ball screw 10 is one moving member, and has a screw shaft 12 having a spiral screw groove 11 formed on an outer peripheral surface serving as a guide surface thereof, and a ball screw 10 having the other moving member. A nut 15 which is a member and has a spiral screw groove 14 formed on an inner peripheral surface 13 serving as a guide surface thereof and opposed to the screw groove 11, and is rotatably interposed between the opposed screw groove. It is schematically configured to include a number of balls 16 that are rolling elements and a tubular circulation path 20 that circulates the balls 16. The tube-type circulation path 20 is formed of a tube having a substantially U-shape in outer shape, and both ends 21 thereof are respectively connected to nuts 15.
Is inserted into a ball rolling space in the nut 15 through a tube mounting hole 22 penetrating in a tangential direction of the two screw grooves 11 and 14, and is fixed to an outer surface of the nut 15 by a stopper 23.
The ball 16 rolling in the spiral ball rolling space moves around the threaded grooves 11 and 14 a plurality of times, and is then picked up at one end 21 of the tube-type circulation path 20 to form the tube-type circulation path 20. , And the circulation from the other end (not shown) to the ball rolling space in the nut 15 is repeated.

[0003]

In an injection molding machine or the like, the ball screw 10 is usually used with a small stroke, a high load, and a high speed. There is a problem that is easy to cause. Therefore, grease used for lubrication of the ball screw 10 includes:
It is common to frequently and intermittently lubricate mineral oil-lithium-based extreme pressure grease containing lithium or lithium composite soap as a thickener and further blended with an extreme pressure agent. As the extreme pressure agent used, for example, solid lubricants such as molybdenum sulfide, organic molybdenum compounds such as molybdenum dialkyldithiocarbamate and molybdenum dialkyldithiophosphate, and organic zinc compounds such as zinc dialkyldithiophosphate are generally used. . However, in recent years, the conditions of use of ball screws have become more severe, and depending on the conditions of use, some may cause damage to the ball screw raceway surface,
Frequent replacement of the ball screw is required. Also,
The greasing interval tends to be shorter, and the amount of grease used is also increasing.

The present invention has been made in view of such a situation, and an object of the present invention is to provide a ball screw having an extended lubrication life.

[0005]

Means for Solving the Problems The present inventors have conducted intensive studies to achieve the above object, and as a result, have found that it is effective to use a grease containing a specific extreme pressure agent. The present invention has been completed. That is, the above object is achieved by a ball screw according to the present invention, which is characterized in that lubrication is performed with grease containing at least one compound selected from an organic nickel compound and an organic tellurium compound.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail. As the grease base oil used in the present invention, mineral oil, synthetic oil, or a mixed oil thereof, which is usually used for grease, can be used. Specifically, mineral oils include paraffinic mineral oils and naphthenic mineral oils.Synthetic hydrocarbon oils include poly-α-olefin oils, and ether oils include dialkyl diphenyl ether oils, alkyl triphenyl ether oils, and the like. Alkyl tetraphenyl ether oils and the like, and ester oils include diester oils, polyol ester oils, and complex ester oils and aromatic ester oils thereof. Above all, in consideration of lubricating performance at high temperature and high speed and lubrication life, it is desirable to contain a synthetic oil, and particularly desirable to contain an ester oil and an ether oil.

The thickener is not particularly limited, either.
For example, metal soaps such as aluminum, barium, calcium, lithium, and sodium, lithium complex, calcium complex, complex metal soaps such as aluminum complex, urea compounds such as diurea, triurea, tetraurea, and polyurea, or inorganic systems such as silica gel and bentonite Compounds, urethane compounds, urea / urethane compounds, sodium terephthalamate compounds and the like can be used as appropriate. By using a urea compound having excellent oxidation stability, the lubricating performance and lubricating life at high temperature and high speed rotation can be further improved. The amount of the thickener is usually 5 to 35% by weight.
And the consistency is preferably about 200 to 450.

The present invention is characterized in that one or more compounds selected from organic nickel compounds and organic tellurium compounds are added to the grease. Specifically, metal salt compounds, coordination compounds, addition compounds, alkyl metal compounds, metal acid esters, metal alkoxides and the like of organic acids having nickel or tellurium as the metal species can be suitably used. As the metal salt compound of an organic acid, an organic carboxylic acid compound, an organic sulfur acid compound, and an organic phosphoric acid compound are preferable, and in particular, a dithiocarbamic acid compound represented by the following general formula (I) or (II): Dithiophosphate compounds are preferred.

[0009]

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In the above general formulas (I) and (II), M is nickel or tellurium. R ¹ and R ² may be the same or different and represent an alkyl group, a cycloalkyl group, an alkenyl group, an aryl group, an alkylaryl group or an arylalkyl group. Particularly preferred groups are 1,1,3,3-tetramethylbutyl group, 1,1,
3,3-tetramethylhexyl group, 1,1,3-trimethylhexyl group, 1,3-dimethylbutyl group, 1-methylundecane group, 1-methylhexyl group, 1-methylpentyl group, 2-ethylbutyl group, 2-ethylhexyl group, 2-methylcyclohexyl group, 3-heptyl group, 4
-Methylcyclohexyl, n-butyl, isobutyl, isopropyl, isoheptyl, isopentyl, undecyl, eicosyl, ethyl, octadecyl, octyl, cyclooctyl, cyclododecyl, cyclopentyl, dimethylcyclohexyl Group,
Decyl group, tetradecyl group, docosyl group, dodecyl group,
Tridecyl group, trimethylcyclohexyl group, nonyl group, propyl group, hexadecyl group, hexyl group, henicosyl group, heptadecyl group, heptyl group, pentadecyl group, pentyl group, methyl group, tert-butylcyclohexyl group, tert-butyl group, 2- Hexenyl group, 2-methallyl group, allyl group, undecenyl group, oleyl group, decenyl group, vinyl group, butenyl group, hexenyl group, heptadecenyl group, tolyl group, ethylphenyl group, isopropylphenyl group, tert-butylphenyl group, Dipentylphenyl group, n-hexylphenyl group, tertiary octylphenyl group, isononylphenyl group, n-dodecylphenyl group,
Phenyl group, benzyl group, 1-phenylethyl group, 2-
Phenylethyl group, 3-phenylpropyl group, 1,1-
Dimethylbenzyl group, 2-phenylisopropyl group, 2
-Phenylhexyl, benzhydryl, biphenyl and the like. Further, these groups may have an ether bond. In addition, general formulas (I) and (I
As a metal salt of an organic acid other than the compound represented by I), for example, a salt of 2-mercaptobenzothiazole with nickel or tellurium is also preferable. Further, metal salts of nickel or tellurium with naphthenic acid or fatty acid can also be preferably used.

Further, as the organic nickel compound or the organic tellurium compound, a compound represented by the following general formula (III) can also be used.

[0012]

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In the general formula (III), M is nickel or tellurium. R ³ and R ⁴ are an alkyl group or an aryl group, which may be the same or different.

The above-mentioned organic nickel compounds and organic tellurium compounds may be used as a mixture of two or more kinds. Further, an organic nickel compound and an organic tellurium compound may be used in combination. The amount of the organic nickel compound and the organic tellurium compound may be the same as the amount of the extreme pressure agent conventionally added to the grease for a ball screw, and is in the range of 0.1 to 15% by weight, preferably 0.5 to 5% by weight. It is. If it is less than this, a sufficient effect of extending the lubrication life cannot be obtained, and if it is more than this, further improvement of the effect cannot be expected. Surface can be adversely affected.

In the present invention, the action of the organonickel compound and the organotellurium compound is not clear, but when the metal contacts under boundary lubrication, the compound is decomposed by the heat generated at the contact surface to protect the heated metal surface. It is considered that a film is formed, and as a result, the load resistance of the rolling surface and the effect of suppressing heat generation are obtained, and the lubrication life is extended.

The organic nickel compound and the organic teur compound may be used in combination with the organic molybdenum compound. As the organic molybdenum compound, molybdenum dialkyldithiocarbamate represented by the following general formula (IV) or molybdenum dithiophosphate represented by the general formula (V) is preferable.

[0017]

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In the general formulas (IV) and (V), R ⁵ , R
⁶ has the same meaning as R ¹ and R ^{2 in} formulas (I) and (II).

It is also preferable to use the compound with a zinc dithiophosphate compound. As the zinc dithiophosphate compound, zinc diaryldithiophosphate, zinc alkyl-aryldithiophosphate, and zinc dialkyldithiophosphate can be suitably used.

It is also preferable to use the compound together with an ashless sulfur compound. Available ashless sulfur compounds include thiol compounds,
Thiazole, sulfenamide, sulfonamide, mercapto, mercaptobenzimidazole,
Thiourea, thiuram (thiocarbamoyl), dithiocarbamic acid, thiophthalimide, thiopropionic acid, thiadiazole, sulfide, polysulfide, thiophthalimide, thiophosphoric, dithiophosphoric, thioaldehyde, Thioketone-based, thioacetal-based, thiocarboxylic acid-based, xanthogenic-acid-based, organic sulfuric acid-based compounds containing no metal element (ashless compounds) can be preferably used. In particular, carbamic acid-based ashless sulfur compounds are preferably used. Is good. Preferred ashless sulfur compounds are shown below. For example, thiocarbanilide, 4,4'-methylenebis (cyclohexylcarbamate), 4,4 '
-Methylenebis (dibutyldithiocarbamate), pentamethylenedithiocarbamate piperazine salt, pentamethylenedithiocarbamate piperidine salt, pipecolyldithiocarbamate pipecoline salt, 2-mercaptomethylbenzimidazole, 2-mercaptotoluimidazole, N-trichloromethylthio-4- Cyclohexane-
1,2-dicarboximide, 2,5-dimercapto-
1,3,4-thiadiazole, dipentamethylenethiuram tetrasulfide, 1,3,4-thiadiazole, 4
-Morpholinyl-2-benzothiazole disulfide,
N, N'-dicyclohexyl-2-benzothiazolesulfenamide, 2- (4-morpholinyldithio) benzothiazole, 2-benzothiazolyl disulfide, N
-Tert-butylbenzothiazolesulfonamide,
N-oxydiethylene-2-benzothiazolesulfonamide, N-cyclohexyl-2-benzothiazolesulfonamide, 2-mercaptobenzothiazole sodium salt, 2- (4'-morpholinodithio) benzothiazole, 2-mercaptobenzothiazole, N -Cyclohexyl-2-benzothiazolylsulfenamide, N-
t-butyl-2-benzothiazolylsulfenamide,
N, N'-dicyclohexyl-2-benzothiazolylsulfenamide, N-tert-butyl-2-benzothiazolesulfenamide, dibenzothiazyl disulfide, tetrakis (2-ethylhexyl) thiuram disulfide, tetrabutylthiuram disulfide, tetra Methylthiuram disulfide, tetraethylthiuram disulfide, dipentamethylenethiuram tetrasulfide, tetrabenzylthiuram disulfide, tetramethylthiuram monosulfide, tetrathiuram monosulfide, diethylthiourea, dilaurylthiourea, 2
-Mercaptothiourea, dibutylthiourea, dimethylthiourea, di-o-toluylthiourea, N, N '
-Diphenylthiourea, distearyl-2,2'-thiodibutyrate, distearylthiopropionate, dilauryl-3,3'-thiopropionate, dimyristylthiopropionate, dilauryl tripropionate, distearyl -3,3'-thiopropionate, ditridecylthiopropionate, hexahydro-1,
3,5-triethyl-s-triazine, 2-hydroxy-4-methoxy-5-sulfobenzophenone trihydrate, 2,5-bis- [5'-tert-butylbenzoxazoyl- (2)] thiophene, thiobis -Methylbutylphenol, 2- (2'-hydroxy-3'-te
rt-butyl-5'-methylphenyl) -5-chlorobenzotriazole, 4,4-thiobis (6-tert-
Butyl-m-cresol), 4,4'-thiobis (6-
tert-butyl-m-cresol), 4,4'-dithiomorpholine, triphenylthiophosphite, trilaurylthiophosphite, triphenylthiophosphite, N, N'-di-sec-undecyldiaminodiphenyl sulfide, N, N'-di-sec-amyl diaminodiphenyl sulfide, N, N'-di-sec
-Dodecyldiaminodiphenyl sulfide, N, N'-
Di-sec-octyldiaminodiphenyl sulfide,
N, N'-di-sec-decyldiaminodiphenyl sulfide, N, N'-di-sec-tridecyldiaminodiphenyl sulfide, N, N'-di-sec-nonyl diaminodiphenyl sulfide, N, N'-di- sec-
Butyldiaminodiphenyl sulfide, N, N'-di-
sec-tetradecyldiaminodiphenyl sulfide,
N, N'-di-sec-heptyldiaminodiphenyl sulfide, N, N'-diisopropyldiaminodiphenyl sulfide, N, N'-di-sec-hexyldiaminodiphenyl sulfide, dibenzyl disulfide,
4,4'-thiobis (2-methyl-6-tert-butylphenol), 4,4'-thiobis (3-methyl-6
-Tert-butylphenol), 4,4'-thiobis (6-tert-butyl-3-methylphenol),
Diethyl 3,5-di-tert-butyl-4-hydroxy-benzylphosphonate, 2-n-octylthio-4,
6-di (4'-hydroxy-3 ', 5'-di-tert
-Butyl) phenoxy-1,3,5-triazine, 2,
2'-thiodiethylbis- [3- (3,5-di-ter
t-butyl-4-hydroxyphenyl) -propionate], 2,2'-thiobis (4-methyl-6-tert)
-Butylphenol), 1,3,5-tris (3,5-
Di-butyl-4-hydroxybenzyl-S-triazine- (1H, 3H, 5H) trione, 1,1'-thiobis- (2-naphthol), and the like, and derivatives of these compounds can be used.

Further, the following known additives can be blended. Further, a solid lubricant such as molybdenum disulfide or graphite may be added. [Antioxidant] rubber, plastic,
The antioxidant, antiozonant, and antioxidant to be added to the lubricating oil and the like are appropriately selected and used. For example, the following compounds can be used. That is, phenyl-1-naphthylamine, phenyl-2-naphthylamine, diphenyl-p-phenylenediamine, dipyridylamine, phenothiazine, N-methylphenothiazine, N-ethylphenothiazine, 3,7-dioctylphenothiazine,
amine compounds such as p, p'-dioctyldiphenylamine, N, N'-diisopropyl-p-phenylenediamine, N, N'-di-sec-butyl-p-phenylenediamine; 2,6-di-tert-di A phenolic compound such as butylphenol can be used.

[Rust inhibitor / metal deactivator] As the rust inhibitor, for example, the following compounds can be used. That is, an ammonium salt of an organic sulfonic acid, an alkali metal such as barium, zinc, calcium, or magnesium, an organic sulfonate or an organic carboxylate of an alkaline earth metal, a phenate, a phosphonate, or an alkyl or alkenyl such as an alkyl or alkenyl succinate. Succinic acid derivatives, partial esters of polyhydric alcohols such as sorbitan monooleate, hydroxy fatty acids such as oleoyl sarcosine, mercapto fatty acids such as 1-mercaptostearic acid or metal salts thereof, higher fatty acids such as stearic acid, Higher alcohols such as isostearyl alcohol, esters of higher alcohols and higher fatty acids, 2,5
Thiazoles such as dimercapto-1,3,4-thiadiazole and 2-mercaptothiadiazole, imidazole compounds such as 2- (decyldithio) -benzimidazole and benzimidazole, or 2,5-bis (dodecyldithio) benzimidazole Or a phosphoric acid ester such as trisnonylphenyl phosphite, or a thiocarboxylic acid ester compound such as dilauryl thiopropionate. Further, nitrite and the like can also be used. As the metal deactivator, for example, a triazole-based compound such as benzotriazole or tolyltriazole can be used.

[Oiling agent] As the oiling agent, for example, the following compounds can be used. That is, fatty acids such as oleic acid and stearic acid, fatty acid alcohols such as oleyl alcohol, fatty acid esters such as polyoxyethylene stearic acid ester and polyglyceryl oleate, phosphoric acid, tricresyl phosphate, lauric acid ester and polyoxyethylene oleyl. Phosphate esters such as ether phosphoric acid can be used.

As described above, the grease composed of each component is not only intermittently lubricated as in the past, but the lubricating life is greatly extended, and the grease is applied to the inside of the ball screw by an appropriate sealing member. It is also possible to use a so-called non-greasing sealing type for sealing. Non-greasing is the most preferable use form in terms of the amount of grease used, and the effect of the present invention is extremely large. Also, in the case of intermittent lubrication, the lubrication interval can be lengthened, so that the amount of grease used can be significantly reduced as compared with the conventional case. There is no limitation on the type of ball screw that can be applied, and the ball screw can be applied to the ball screw shown in FIG.

[0025]

The present invention will be further described below with reference to examples and comparative examples. (Examples 1 to 8 and Comparative Examples 1 to 4) Tables 1 to 3 were applied to a ball screw (nominal number: BS8020-7.5) having a shaft diameter of 80 mm.
Each of the greases prepared as shown in Table 1 was sealed, and the grease was continuously operated without lubrication, and the number of reciprocating cycles until peeling occurred and burning was measured. The lithium complex used was a lithium salt of azelaic acid and 12-hydroxystearic acid, and the urea compound was octylamine and 4,4.
Reaction product with 4'-diphenylmethane diisocyanate, organic nickel compound is nickel dibutylcarbamate, organic tellurium compound is diethyldithiocarbamate tellurium, antioxidant is phenyl-1-naphthylamine, organic molybdenum compound is "Sakura Lube 600" (Asahi Denka The measurement was performed under the conditions of a cycle time of 3 seconds, a temperature of 120 ° C., and a lead of 20 mm by pressing a disc spring so that the maximum load was 30 tons. I do.

[0026]

[Table 1]

[0027]

[Table 2]

[0028]

[Table 3]

As can be seen from Tables 1 to 3, the use of a grease containing at least one of an organic nickel compound and an organic tellurium compound significantly increases both the number of cycles of peeling and the number of cycles of seizure, and extends the lubrication life. The effect was recognized. Particularly, by using a urea compound having excellent heat resistance as a thickener, the lubrication life can be further extended.

[0030]

As described above, according to the present invention,
A ball screw having a significantly extended lubrication life is provided.

[Brief description of the drawings]

FIG. 1 is a sectional view of a main part showing an example of a ball screw.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Ball screw 11 Screw groove 12 Screw shaft 14 Screw groove 15 Nut 16 Ball 20 Tube type circulation path 22 Tube mounting hole

Continued on the front page (72) Inventor Kazuo Miyaguchi 78 Tobacho, Maebashi-shi, Gunma Nippon Seiko Co., Ltd. Inventor Michiharu Naka 1-5-50 Kugenuma Shinmei, Fujisawa-shi, Kanagawa F-term in NSK Ltd. (reference) 4H104 BB15C BB26C BG10C BG17C BH07C DA02A EB02 EB06 FA06 FA08 LA03 PA50 QA18

Claims (1)

[Claims] 1. A ball screw lubricated by grease containing at least one compound selected from an organic nickel compound and an organic tellurium compound.