Lubricant composition for speed reducer and speed reducer
By using lubricant compositions of synthetic oil, hydrocarbon-based wax and specific calcium salts in the reducer, the problems of short life at high temperatures and increased torque at low temperatures are solved, and stable performance and efficient start-up in various environments are achieved .
Patent Information
- Application Number
- CN202411286372.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Priority Date
- 2015-12-25
- Filing Date
- 2016-12-16
- Publication Date
- 2024-12-17
AI Technical Summary
The existing reducers have short life at high temperatures and the input torque at low temperatures, making it difficult to maintain stable performance in various environments.
The lubricant composition containing synthetic oil, hydrocarbon-based wax and specific calcium salts, such as calcium salts of alkyl aromatic sulfonic acid and calcium salts of oxidized wax, is used as lubricant for the eccentric oscillating planetary gear reducer, and is adjusted. Kinematic viscosity and chemical composition for improved high-temperature durability and low-temperature torque control.
It significantly extends the high temperature life of the reducer, reduces the input torque at low temperatures, improves the starting efficiency, and adapts to a variety of environmental conditions.
Smart Images
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Abstract
Description
[0001] The present invention is a divisional application of the invention application with application number 201611168208X, application date December 16, 2016, and invention name “Lubricant composition for reducer and reducer”. Technical Field
[0002] The present invention relates to a lubricant composition for an eccentric oscillating planetary gear type speed reducer, and an eccentric oscillating planetary gear type speed reducer using the lubricant composition. Background Art
[0003] The interior of the speed reducer is composed of multiple sliding parts and rolling parts. If torque is applied to the input side, it will be decelerated and high torque will be transmitted to the output side. Such speed reducers are widely used in transportation fields such as railways, aviation, and ships, as well as industrial fields such as robots.
[0004] As one of the performance characteristics of a reducer, the output torque is required to remain constant for a long time without changing. In particular, in a reducer installed on the joint of a robot (for example, the eccentric swing reducer described in Patent Document 1), in order to achieve precise movements, it is required to suppress the fluctuation of the output torque as much as possible. However, there is a problem that the shape of the internal components of the reducer changes after the operation, for example, the fluctuation of the output torque becomes larger due to damage to the metal contact part when steel slides against steel. This problem becomes particularly significant at high temperatures, and if the high temperature is reached, the life of the reducer becomes shorter.
[0005] As a lubricant composition for a speed reducer, a lubricating oil or grease having a high internal friction reduction effect and a high speed reducer efficiency improvement effect in which a calcium salt is compounded in molybdenum dithiocarbamate is proposed (for example, Patent Document 2). However, the lubricant composition containing molybdenum dithiocarbamate and a calcium salt is not sufficient in improving the life of the speed reducer at high temperatures.
[0006] In addition, as the use environment of the reducer expands, it is required to be able to use the reducer in cold regions, etc. In cold regions, at low temperatures such as winter, the input side torque (starting torque) increases, and the starting efficiency of the reducer decreases. Therefore, it is desired to develop a lubricant composition for a reducer that has not only durability at high temperatures but also reduced input torque at low temperatures.
[0007] Prior art literature
[0008] Patent Literature
[0009] Patent Document 1: Japanese Patent Application Laid-Open No. 2006-077980
[0010] Patent Document 2: Japanese Patent Application Laid-Open No. 2004-339411 Summary of the invention
[0011] Problems to be solved by the invention
[0012] Therefore, an object of the present invention is to provide a lubricant composition for an eccentric oscillating planetary gear type speed reducer having a long life at high temperatures and a low input torque at low temperatures.
[0013] Another object of the present invention is to provide an eccentric oscillating planetary gear type speed reducer having a long life at high temperatures and a low input torque at low temperatures.
[0014] Methods for solving problems
[0015] In order to achieve the above-mentioned object, the present invention provides the following.
[0016] 1. A lubricant composition for an eccentric oscillating planetary gear type reducer, characterized in that it contains the following components (a) to (c):
[0017] (a) Base oils containing synthetic oils,
[0018] (b) hydrocarbon wax, and
[0019] (c) at least one calcium salt selected from the group consisting of calcium salts of petroleum sulfonic acids, calcium salts of alkyl aromatic sulfonic acids, calcium salts of oxidized waxes, overbased calcium salts of petroleum sulfonic acids, overbased calcium salts of alkyl aromatic sulfonic acids, and overbased calcium salts of oxidized waxes.
[0020] 2. The lubricant composition for a speed reducer according to 1, wherein the (b) hydrocarbon wax is at least one selected from the group consisting of polyethylene wax and polypropylene wax.
[0021] 3. The lubricant composition for a speed reducer according to 1 or 2, wherein the content of the (b) hydrocarbon wax is 0.1 to 20% by mass in the entire composition.
[0022] 4. The lubricant composition for a reduction machine according to any one of 1 to 3, wherein the synthetic oil in the (a) base oil is a synthetic hydrocarbon oil.
[0023] 5. The lubricant composition for a speed reducer according to any one of 1 to 4, wherein (a) the base oil has a kinematic viscosity of 20 to 300 mm at 40°C. 2 / s.
[0024] 6. The lubricant composition for a reducer according to any one of 1 to 5, wherein the calcium salt (c) is a calcium salt of an alkyl aromatic sulfonic acid or a high-based calcium salt of an alkyl aromatic sulfonic acid.
[0025] 7. An eccentric oscillating planetary gear type speed reducer, wherein the speed reducer lubricant composition according to any one of 1 to 6 is enclosed.
[0026] Effects of the Invention
[0027] The lubricant composition for reducer of the present invention can improve the life of the reducer at high temperature compared with the conventional lubricant composition for reducer. Therefore, the reducer of the present invention enclosed with the lubricant composition has a long life even at high temperature. In addition, the lubricant composition for reducer of the present invention can suppress the increase of input torque at low temperature. Therefore, the reducer of the present invention enclosed with the lubricant composition can be suitable for use even in cold areas. Furthermore, the lubricant composition for reducer of the present invention can increase the starting efficiency of the reducer. DETAILED DESCRIPTION
[0028] 1. Base oil
[0029] The (a) base oil used in the present invention has synthetic oil as an essential component and may further contain other base oils such as mineral oil. As the synthetic oil, any of the synthetic oils that can be used in a common lubricant composition, such as synthetic hydrocarbon oil, ester oil, phenylene ether, polyethylene glycol, etc., can be used. One synthetic oil can be used alone, or two or more synthetic oils can be used in combination. The preferred synthetic oil is a synthetic hydrocarbon oil. As a synthetic hydrocarbon oil, specifically, a hydrocarbon oil obtained by mixing and polymerizing one or more α-olefins can be cited. As α-olefins, α-olefins produced using ethylene, propylene, butene, their derivatives, etc. as raw materials can be cited, and α-olefins with 6 to 18 carbon atoms (for example, 1-decene, 1-dodecene, etc.) can be preferably cited. The most preferred synthetic hydrocarbon oil is a poly-α-olefin (PAO) which is a oligomer of 1-decene and 1-dodecene.
[0030] The base oil is preferably a base oil containing a synthetic hydrocarbon oil (eg, PAO), and more preferably a combination of a synthetic hydrocarbon oil (eg, PAO) and a mineral oil.
[0031] The ratio of the synthetic oil (for example, synthetic hydrocarbon oil such as PAO) in the base oil is preferably 10 to 100 mass %, more preferably 10 to 50 mass % (for example, 10 to 20 mass %). If it is less than 10 mass %, the input torque at low temperature may increase.
[0032] The ratio of the base oil in the lubricant composition is preferably 50 to 99% by mass, more preferably 70 to 95% by mass.
[0033] The kinematic viscosity of the base oil used in the present invention at 40° C. is, for example, 20 to 300 mm 2 / s, preferably 30 to 220 mm 2 / s (for example, 40 to 200 mm 2 / s), more preferably 50 to 150 mm 2 / s (especially 60~100mm 2 / s). If it is less than 20mm2 / s, the service life at high temperatures tends to be insufficient. In addition, if it exceeds 300mm 2 / s, there is a tendency for a startup failure to occur at low temperatures. The kinematic viscosity at 40°C is measured by a method in accordance with JIS K 2283.
[0034] 2. Hydrocarbon wax
[0035] The (b) hydrocarbon wax used in the present invention is not particularly limited, and for example comprises at least one compound selected from the group consisting of polyolefin waxes (polyethylene wax, acidified polyethylene wax, polypropylene wax, ethylene-propylene copolymer wax, etc.), montan wax, and amide wax.
[0036] Among hydrocarbon waxes, polyolefin waxes are preferred. The weight average molecular weight of the polyolefin wax is not particularly limited, and is, for example, about 1,000 to 20,000. In addition, the melt viscosity of the polyolefin wax is not particularly limited, and may be, for example, 25,000 to 30,000 mPa·s at 140°C, or 9,000 to 10,000 mPa·s at 170°C. Furthermore, the density of the polyolefin wax is not particularly limited, and may be a high density (for example, 0.96 g / cm 3 Above), medium density (for example, 0.94-0.95 g / cm 3 ) and low density (e.g., 0.93 g / cm 3 If it is high density, it has the characteristics of high melting point, softening point, degree of crystallinity, and high hardness. If it is low density, it has the characteristics of low melting point and softening point and softness. Regarding polyolefin wax, from the viewpoint of heat resistance, the dropping point is preferably 100°C or more, more preferably 110°C or more. From the viewpoint of solubility in base oil, the dropping point is preferably 150°C or less, more preferably 135°C or less. In addition, the acid value of the polyolefin wax is preferably 0 to 10 mgKOH / g, more preferably 0 to 5 mgKOH / g. If the acid value is within such a range, the acid component has little effect on the oxidative degradation of the lubricant composition, so it is preferred.
[0037] Among the polyolefin waxes, at least one selected from the group consisting of polyethylene waxes, polypropylene waxes and ethylene-propylene copolymer waxes is preferred, and at least one selected from the group consisting of polyethylene waxes and polypropylene waxes is more preferred.
[0038] Commercially available polyethylene waxes include Licowax PE520, PE190, and PE130 manufactured by Nippon Clariant Co., Ltd. Commercially available polypropylene waxes include Licosen PP7502, PP 3602, and Ceridust 6050M manufactured by Nippon Clariant Co., Ltd. and Hi-WAX NP105 and NP500 manufactured by Mitsui Chemicals, Inc.
[0039] The most preferred hydrocarbon wax is polypropylene wax.
[0040] The proportion of the hydrocarbon wax in the lubricant composition is, for example, 0.1 to 20 mass %, preferably 0.1 to 10 mass %, more preferably 0.5 to 7 mass %, and further preferably 1 to 5 mass %.
[0041] 3. Calcium salt
[0042] The (c) calcium salt used in the present invention is at least one selected from the group consisting of calcium salts of petroleum sulfonic acids, calcium salts of alkyl aromatic sulfonic acids, calcium salts of oxidized waxes, overbased calcium salts of petroleum sulfonic acids, overbased calcium salts of alkyl aromatic sulfonic acids and overbased calcium salts of oxidized waxes.
[0043] It should be noted that, in this specification, "high alkaline calcium salt of X" refers to a calcium salt of X having an alkalinity value of 200 mgKOH / g or more as measured in accordance with JIS K 2501. In addition, when simply described as "calcium salt of X", the "calcium salt of X" refers to a calcium salt other than a high alkaline calcium salt (neutral or alkaline calcium salt), that is, a calcium salt of X having an alkalinity value of less than 200 mgKOH / g as measured in accordance with JIS K 2501.
[0044] The calcium salt is preferably at least one selected from the group consisting of calcium salts of alkyl aromatic sulfonic acids and highly basic calcium salts of alkyl aromatic sulfonic acids, and more preferably a combination of calcium salts of alkyl aromatic sulfonic acids and highly basic calcium salts of alkyl aromatic sulfonic acids. In the above combination, the proportion of highly basic calcium salts of alkyl aromatic sulfonic acids is, for example, 50 to 99% by mass, preferably 60 to 90% by mass, and more preferably 65 to 80% by mass. The above combination further improves durability at high temperatures.
[0045] The ratio of the calcium salt in the lubricant composition is preferably 0.1 to 20% by mass, more preferably 0.5 to 10% by mass (e.g., 1 to 5% by mass). When it is less than 0.1% by mass, the life at high temperatures tends to be insufficient, and when it exceeds 20% by mass, the effect corresponding to the amount added tends to be insufficient.
[0046] 4. Thickener
[0047] The lubricant composition of the present invention may contain (d) a thickener. As the thickener, all thickeners may be cited. For example, soap thickeners represented by lithium soap and complex lithium soap, urea thickeners represented by diurea, inorganic thickeners represented by organoclay and silica, organic thickeners represented by PTFE, etc., preferably lithium soap thickeners and urea thickeners, more preferably lithium soap thickeners.
[0048] The ratio of the thickener in the lubricant composition is preferably 0 to 20% by mass (e.g., 1 to 15% by mass), and more preferably 0.5 to 10% by mass (e.g., 0.5 to 3% by mass). When the ratio is less than 0.5% by mass, the thickening effect disappears, and when the ratio exceeds 20% by mass, the lubricant composition becomes too hard, and the flow into the lubricated part disappears, and there is a tendency that it is difficult to obtain a sufficient effect.
[0049] When the lubricant composition contains a thickener, the viscosity of the lubricant composition is preferably 300 to 450 (for example, 350 to 410), and more preferably 395 to 425. The viscosity is a value measured immediately after a sample is mixed 60 times in a predetermined mixer as defined in JIS K2220.
[0050] The lubricant composition of the present invention may be formulated with any other additives as required. Examples of such additives include (c) rust inhibitors or detergent dispersants other than calcium salts, extreme pressure agents, antioxidants, metal corrosion inhibitors, oiliness agents, anti-wear agents, solid lubricants, and the like.
[0051] Among them, (e) extreme pressure agents are preferred.
[0052] 5. Extreme pressure agent
[0053] The (e) extreme pressure agent arbitrarily used in the present invention is not particularly limited, and for example, at least one selected from thiophosphates and thiocarbamic acids can be used. As the thiophosphates, dithiophosphates can be cited, preferably zinc salts or molybdenum salts of dithiophosphoric acids (e.g., dialkyldithiophosphoric acids). In addition, as the thiocarbamic acids, dithiocarbamates can be cited, preferably zinc salts or molybdenum salts of dithiocarbamic acids (e.g., dialkyldithiocarbamic acids).
[0054] The preferred extreme pressure agent is at least one selected from the group consisting of molybdenum dithiocarbamate and zinc dithiophosphate, and the more preferred extreme pressure agent is a combination of molybdenum dithiocarbamate (particularly molybdenum dialkyl dithiocarbamate) and zinc dithiophosphate (particularly zinc dialkyl dithiophosphate). The ratio of molybdenum dithiocarbamate in the above combination is preferably 50 to 99% by mass, more preferably 55 to 90% by mass.
[0055] The ratio of the extreme pressure agent in the lubricant composition is preferably 0 to 1.5% by mass, more preferably 0.5 to 1% by mass. If it exceeds 1.5% by mass, the probability of vibration of the reducer due to precipitation of the additive increases.
[0056] As one of the preferred embodiments of the lubricant composition of the present invention, the following embodiments can be mentioned.
[0057] A lubricant composition for an eccentric oscillating planetary gear type reducer, comprising the following components (a) to (e):
[0058] (a) a base oil comprising a synthetic hydrocarbon oil,
[0059] (b) at least one selected from the group consisting of polyethylene wax and polypropylene wax,
[0060] (c) at least one selected from the group consisting of calcium salts of alkyl aromatic sulfonic acids and overbased calcium salts of alkyl aromatic sulfonic acids,
[0061] (d) lithium soap thickener, and
[0062] (e) At least one selected from the group consisting of molybdenum dithiocarbamate and zinc dithiophosphate.
[0063] The lubricant composition of the present invention can be used in an eccentric swing type planetary gear type reducer. In particular, from the perspective of durability at high temperatures and the ability to prevent changes in output side torque, it is preferably used in an eccentric swing type planetary gear type reducer installed on a joint portion of a robot. As a representative example of the above reducer, the following eccentric swing type reducer can be cited: comprising a first-stage reduction mechanism and a second-stage reduction mechanism, the first-stage reduction mechanism reduces the rotation of the engine and transmits it to the second-stage reduction mechanism, the second-stage reduction mechanism having an internal gear body, an external gear body meshing with the internal gear body, a crankshaft meshing with the external gear body and causing the external gear body to perform an eccentric swing motion relative to the internal gear body, and a support body that rotatably supports the crankshaft, and the output can be taken out from the internal gear body or the support body.
[0064] Example
[0065] Hereinafter, the present invention will be described in more detail based on Examples, but the present invention is not limited to these Examples.
[0066] Examples 1 to 4 and Comparative Examples 5 to 7
[0067] The components shown in Table 1 were mixed in the proportions shown in Table 1 to prepare lubricant compositions of Examples 1 to 4 and Comparative Examples 5 to 7. For these lubricant compositions, the kinematic viscosity and worked penetration of the base oil were measured by the following methods.
[0068] Kinematic viscosity of base oil: The kinematic viscosity of the base oil was measured in accordance with JIS K 2220 23 at a temperature of 40°C.
[0069] Worked cone penetration: The worked cone penetration is as defined in JIS K 2220 7 and is measured immediately after a sample has been mixed by 60 reciprocating strokes in a specified mixer.
[0070] Furthermore, the lubricant composition was sealed in an eccentric oscillating planetary gear type reducer (RV-42N3-127.15 manufactured by Nabtesco Corporation), and a life test, a torque measurement test at low temperature, and a starting efficiency test were conducted.
[0071] Life test: The prepared lubricant composition was tested under the following test conditions, and the time until the internal member was damaged was measured.
[0072] 1) Test conditions
[0073] Test temperature: 60℃
[0074] The load torque and output speed can be set arbitrarily, and the bearing life can be calculated according to the bearing life conversion formula.
[0075] Regarding high temperature durability, a relative life ratio (relative life ratio when the life of Comparative Example 6 is set to 1) was calculated and evaluated based on the following pass / fail determination.
[0076] 2) Qualification
[0077] Relative life ratio is 3.0 or more◎ (passed)
[0078] Relative life ratio is 2.5 or more and less than 3.0○ (pass)
[0079] Relative life ratio is less than 2.5× (unqualified)
[0080] Torque measurement test at low temperature: The prepared lubricant composition was tested under the following test conditions, and the torque of the input shaft required to rotate the speed reducer under no load was read to measure the input torque at low temperature.
[0081] 1) Test conditions
[0082] Test temperature: -10℃
[0083] Load torque (radial load (direction perpendicular to the axial direction)): No load
[0084] Output speed: 15.7rpm
[0085] Regarding the low temperature property, a relative torque ratio (relative torque ratio when the torque of Comparative Example 5 is set to 1) was calculated and evaluated based on the following pass / fail determination.
[0086] 2) Qualification
[0087] Relative torque ratio is 0.4 (-10℃) or less ○ (pass)
[0088] Relative torque ratio exceeds 0.4 (-10°C) × (failed)
[0089] Starting efficiency test: The prepared lubricant composition was tested under the following test conditions to measure the starting efficiency (the actual output torque when the output torque (theoretical value) with respect to the torque output of the input shaft of 100% was set as 100).
[0090] 1) Test conditions
[0091] Test temperature: 25℃
[0092] Load torque (radial load (direction perpendicular to the axial direction)): 42kgf-m
[0093] Regarding the startup efficiency, a relative efficiency ratio (relative efficiency ratio when the efficiency of Comparative Example 6 is set to 1) was calculated and evaluated based on the following criteria.
[0094] 2) Qualification or failure determination>
[0095] Relative efficiency is 1.4 or above◎(Pass)
[0096] Relative efficiency is 1.2 or more and less than 1.40 (qualified)
[0097] Relative efficiency is less than 1.2× (unqualified)
[0098] 3) Comprehensive judgment
[0099] High temperature durability, low temperature performance, and starting efficiency are all qualified○ (qualified)
[0100] Any one failed × (failed)
[0101] Table 1 shows the results of the prepared lubricant compositions.
[0102] [Table 1]
[0103]
[0104] The details of (b) hydrocarbon wax, (c) calcium salt, (d) thickener, and (e) extreme pressure agent in Table 1 are as follows.
[0105] Hydrocarbon wax
[0106] Polyethylene wax: melt viscosity about 25000mPa·s (140℃), density 0.96g / cm 3 , Dropping point 135℃ polypropylene wax: melt viscosity about 9000mPa·s (170℃), density 0.90g / cm 3 , Calcium salt with dropping point of 112℃
[0107] Calcium sulfonate A (high base): calcium salt of alkyl aromatic sulfonic acid (manufactured by The Lubrizol Corporation, trade name: LUBRIZOL 5283C, base number: 375 mgKOH / g)
[0108] Calcium sulfonate B (neutral): calcium salt of alkyl aromatic sulfonic acid (manufactured by KING INDUSTRIES, trade name: NA-SUL729, base value 1 mgKOH / g or less)
[0109] Thickener
[0110] Lithium soap thickener: Lithium hydroxystearate obtained by reacting 12-hydroxystearic acid and a lithium hydroxide aqueous solution in a base oil, heating to 225°C, and then cooling to 100°C or less.
[0111] Extreme Pressure Agents
[0112] MoDTC: Molybdenum dialkyl dithiocarbamate, manufactured by ADEKA, trade name ADEKA SAKURA-LUBE 515
[0113] ZnDTP: zinc dialkyl dithiophosphate, manufactured by Infineum Co., Ltd., trade name INFINEUM C9421
[0114] As shown in Table 1, the lubricant compositions of Examples 1 to 4 of the present invention have better low temperature properties than Comparative Example 5 which does not contain synthetic hydrocarbon oil in the base oil. In addition, the lubricant compositions of Examples 1 to 4 of the present invention have better high temperature durability and starting efficiency than Comparative Example 6 which does not contain hydrocarbon wax in the additives and Comparative Example 7 which does not contain calcium sulfonate.
[0115] It was found that Example 3 further containing calcium sulfonate B and Example 4 further containing calcium sulfonate B and zinc dialkyl disulfide had better high-temperature durability and startup efficiency.
Claims
1. A lubricant composition for an eccentric oscillating planetary gear type reducer, characterized in that: Contains the following ingredients (a) to (c): (a) Base oils containing synthetic oils, (b) hydrocarbon wax, and (c) at least one calcium salt selected from the group consisting of calcium salts of petroleum sulfonic acids, calcium salts of alkyl aromatic sulfonic acids, calcium salts of oxidized waxes, overbased calcium salts of petroleum sulfonic acids, overbased calcium salts of alkyl aromatic sulfonic acids, and overbased calcium salts of oxidized waxes.
2. The lubricant composition for a speed reducer according to claim 1, wherein (b) The hydrocarbon wax is at least one selected from the group consisting of polyethylene wax and polypropylene wax.
3. The lubricant composition for a speed reducer according to claim 1 or 2, wherein: The content of the (b) hydrocarbon wax is 0.1 to 20% by mass in the entire composition.
4. The lubricant composition for a speed reducer according to any one of claims 1 to 3, wherein (a) The synthetic oil in the base oil is a synthetic hydrocarbon oil.
5. The lubricant composition for a speed reducer according to any one of claims 1 to 4, wherein (a) The kinematic viscosity of the base oil at 40°C is 20 to 300 mm 2 / s.
6. The lubricant composition for a speed reducer according to any one of claims 1 to 5, wherein (c) The calcium salt is a calcium salt of an alkyl aromatic sulfonic acid and a highly basic calcium salt of an alkyl aromatic sulfonic acid.
7. An eccentric swing planetary gear type reducer, characterized in that: The lubricant composition for a reduction machine according to any one of claims 1 to 6 is enclosed.