Rolling bearing device

Abstract

The present invention provides a rolling bearing device capable of ensuring lubrication durability in grease lubrication even under high-speed rotation conditions and capable of suppressing temperature rise during inertial operation. A rolling bearing device (20) is provided with: a radial thrust ball bearing (1) having an inner ring (2), an outer ring (3), a plurality of balls (4) interposed between the inner ring (2) and the outer ring (3), and a grease composition (7) sealed in a bearing space between the inner ring (2) and the outer ring (3), the grease composition (7) containing a base oil having a kinematic viscosity of less than 120 mm2 / s at 40 DEG C and a thickener comprising a urea compound; and a mixture consistency of 230 to 300 as determined according to JIS K2220; and a lubricating oil supply mechanism (11) for supplying lubricating oil into the bearing space of the radial thrust ball bearing (1) and supplying the lubricating oil to the raceway surface.

Description

Technical Field

[0001] The present invention relates to a rolling bearing device having a rolling bearing and a lubricating oil supply mechanism, and particularly to a rolling bearing device for supporting a main shaft of a working machine. Background Art

[0002] In order to improve machining efficiency, the main shaft of a working machine is preferably a high-speed rotating main shaft, and various lubrication techniques are applied to the bearing. As lubrication methods suitable for high-speed rotating main shafts, for example, air-oil lubrication, oil mist lubrication, etc. are known.

[0003] In recent years, in the field of working machines, the demand for carbon neutrality and further cost reduction has also increased, and accordingly, the demand for grease lubrication has increased. Since grease lubrication does not require an air-oil supply device, which is an auxiliary device required for air-oil lubrication, and a structure for injecting air-oil into the bearing, it is environmentally friendly and can suppress initial costs and operating costs.

[0004] However, on the other hand, since grease lubrication is performed only by the initial grease sealed during bearing assembly, in high-speed rotation applications, due to the heat generation of the bearing, the grease deteriorates prematurely, and it is difficult to ensure lubrication durability. Therefore, in grease lubrication, it is required to cope with further high-speed operation (improve lubrication durability). Generally, for greases for rolling bearings in high-speed rotation applications, a urea compound is used as a thickener. Urea-based grease forms a coating film on the bearing raceway surface and assists lubrication, so it is excellent in lubrication durability under high-speed rotation compared to metal-based greases that do not form the same coating film.

[0005] In addition, although urea-based grease has the above-mentioned advantages, on the other hand, it is difficult to perform oil separation, and under further high-speed rotation conditions (for example, when the dn value [d (bearing inner diameter, mm) × n (rotation speed, min -1 is 110×10 4 above), it is possible that the oil film formation is insufficient. Therefore, when performing grease lubrication for such applications, it is preferable to add a grease that assists in oil film formation. As related prior art, for example, in Patent Document 1, a method of simultaneously using urea-based grease and a grease with good oil separation property is shown.

[0006] Prior Art Documents

[0007] Patent Documents

[0008] Patent Document 1: Japanese Patent No. 5916781 Gazette Summary of the Invention

[0009] Problems to be Solved by the Invention

[0010] However, for the technology of Patent Document 1, it is difficult to control the configuration of the two greases in the bearing space, the amount of base oil, the operation, etc., and there is room for improvement in terms of reliability.

[0011] In addition, in the case of rolling bearings used in high-speed rotation such as the bearings for the main shaft of construction machinery, since the rotational speed during inertial operation is also implemented in the high-rotation region, temporary temperature rise is likely to occur during inertial operation. Moreover, if the temporary temperature rise is large, it is necessary to stop the inertial operation each time, and from the viewpoint of workability, it is preferable to suppress such a temperature rise.

[0012] The present invention has been completed in view of such circumstances, and an object thereof is to provide a rolling bearing device that can ensure lubrication durability in grease lubrication even under high-speed rotation conditions and can suppress the temperature rise during inertial operation.

[0013] Means for Solving the Problems

[0014] The rolling bearing device of the present invention includes: a rolling bearing having an inner ring, an outer ring, a plurality of rolling elements interposed between the inner ring and the outer ring, and a grease composition sealed in the bearing space between the inner ring and the outer ring, the grease composition containing a base oil having a kinematic viscosity at 40°C of less than 120 mm 2 / s and a thickener composed of a urea compound, and having a mixed consistency of 230 to 300 as measured according to JIS K 2220; and a lubricating oil supply mechanism that supplies lubricating oil into the bearing space of the rolling bearing and supplies the lubricating oil to the raceway surface.

[0015] The rolling bearing device is characterized in that the base oil and the lubricating oil are respectively selected from the group consisting of synthetic hydrocarbon oils, ester oils, and a mixed oil of synthetic hydrocarbon oils and ester oils.

[0016] The rolling bearing device is characterized in that the base oil and the lubricating oil both have a kinematic viscosity at 40°C of 10 mm 2 / s to 50 mm 2 / s.

[0017] The rolling bearing device is characterized in that the grease composition has a mixed consistency of 250 to 280 as measured according to JIS K 2220.

[0018] The rolling bearing device is characterized in that the urea compound is a biurea compound obtained by reacting a diisocyanate component with a monoamine component, and the monoamine component includes an aliphatic monoamine.

[0019] The rolling bearing device is characterized in that the base oil and the lubricating oil are respectively selected from the group consisting of synthetic hydrocarbon oils, ester oils, and mixed oils of synthetic hydrocarbon oils and ester oils, and the kinematic viscosities of the base oil and the lubricating oil at 40 °C are both 10 mm 2 / s to 50 mm 2 / s, and the mixed consistency of the grease composition measured according to JIS K 2220 is 250 to 280.

[0020] The rolling bearing device is characterized in that the lubricating oil supply mechanism sprays lubricating oil near the raceway surface of the inner ring.

[0021] Effects of the Invention

[0022] The rolling bearing device of the present invention includes a rolling bearing in which a grease composition contains a base oil having a specified kinematic viscosity at 40 °C and a thickener composed of a urea compound and has a mixed consistency of 230 to 300, and a lubricating oil supply mechanism that supplies lubricating oil into the bearing space of the rolling bearing and supplies the lubricating oil to the raceway surface. Therefore, by supplying lubricating oil while using a urea-based grease that is more advantageous in terms of lubrication durability, oil shortage on the raceway surface is prevented, and an oil film is easily formed even under high-speed rotation conditions. In addition, as described later, by supplying lubricating oil, aggregation of the thickener is eliminated, so that the progression of deterioration of the urea-based grease can be suppressed. Thus, lubrication durability can be ensured in grease lubrication even under high-speed rotation conditions. In addition, according to the above grease composition, the temperature rise during inertial operation can also be appropriately suppressed.

[0023] Since the base oil and the lubricating oil are respectively selected from the group consisting of synthetic hydrocarbon oils, ester oils, and mixed oils of synthetic hydrocarbon oils and ester oils, and in addition, the kinematic viscosities of the base oil and the lubricating oil at 40 °C are both 10 mm 2 / s to 50 mm 2 / s, it is easy to eliminate the aggregation of the thickener, and in addition, it is easy to supply lubricating oil to the raceway surface.

[0024] Since the mixed consistency of the grease composition measured according to JIS K 2220 is 250 to 280, it is easier to eliminate the aggregation of the thickener.

[0025] Since the urea compound is a biurea compound obtained by reacting a diisocyanate component with a monoamine component, and the monoamine component contains an aliphatic monoamine, it is suitable for use under high-speed rotation conditions, and in addition, it is also advantageous in eliminating the aggregation of the thickener.

[0026] Since the lubricating oil supply mechanism sprays lubricating oil near the raceway surface of the inner ring, lubricating oil can be supplied to the raceway surface while suppressing the influence of torque fluctuation caused by oil supply. Description of the Drawings

[0027] Figure 1 This is a schematic diagram showing an example of the rolling bearing device of the present invention.

[0028] Figure 2 This is a diagram showing an outline of the calculation of the adhesion work.

[0029] Figure 3 This is a diagram showing the trace of the ester oil based on the infrared spectrum.

[0030] Figure 4 This is a diagram showing the microscopic image of the grease composition. Detailed Description of the Invention

[0031] The present inventors have conducted in-depth research in grease lubrication in order to improve the lubrication durability under high-speed rotation conditions and the like. As a result, it has been found that in the case of using urea-based grease, if the oil separation of the grease progresses and the ratio of the thickener in the grease becomes high, it is sheared as the bearing rotates and partially coagulates. And it has been found that by supplying lubricating oil in such a state, while eliminating the oil shortage on the raceway surface, the coagulation of the thickener is released. The present invention has been completed based on such an insight.

[0032] The rolling bearing device of the present invention is used for a mechanical device such as a main shaft for a working machine that is particularly used during high-speed rotation. For example, the main shaft for a working machine includes: a rotating shaft; an inner cylinder of the housing; an outer cylinder of the housing, disposed on the outer periphery of the inner cylinder of the housing; and a bearing device that rotatably holds the rotating shaft relative to the inner cylinder of the housing. Moreover, the bearing device has a rolling bearing. In this main shaft, the rolling bearing can also be positioned by an inner ring spacer and an outer ring spacer respectively interposed on the inner ring side and the outer ring side.

[0033] According to Figure 1 An example of the rolling bearing device of the present invention will be described. As Figure 1 shown, the rolling bearing device 20 includes a radial thrust ball bearing 1 and a lubricating oil supply mechanism 11 that supplies lubricating oil into the bearing space of the radial thrust ball bearing 1. In Figure 1 it, the lubricating oil supply mechanism 11 is shown in a functional block diagram.

[0034] As Figure 1As shown in the figure, the angular contact ball bearing 1 includes: an inner ring 2 having an inner ring raceway surface 2a on its outer peripheral surface; an outer ring 3 having an outer ring raceway surface 3a on its inner peripheral surface; a plurality of balls 4 interposed between the inner ring raceway surface 2a and the outer ring raceway surface 3a; and a cage 5 that holds the balls 4 at constant intervals in the circumferential direction. The inner ring 2 and the outer ring 3 are in contact with the balls 4 at a prescribed angle θ (contact angle) with respect to the radial center line, and can bear radial loads and axial loads in one direction. The cage 5 is of the outer ring guiding type and is guided by the outer ring 3 through the contact between the outer ring guiding surface 5a of the cage 5 and the inner peripheral surface of the outer ring 3. The outer ring guiding surface 5a is provided on a part of the outer peripheral surface of the cage 5 (both axial end portions).

[0035] A prescribed amount of grease composition 7 is pre-filled in the bearing space between the inner ring 2 and the outer ring 3. A sealing member 6 is installed at one axial end of the bearing space. The inner ring 2 and the outer ring 3 are made of ferrous metal materials, and the grease composition 7 is interposed between the raceway surfaces in contact with the balls 4 for lubrication.

[0036] As Figure 1 shown in the figure, the lubricating oil supply mechanism 11 has a power supply unit 12, a control unit 13, a drive unit 14, a pump 15, and a fuel tank 16. The power supply unit 12 is connected to the control unit 13 and the drive unit 14 in a manner that can supply power to each of them respectively. The control unit 13 is, for example, a microcomputer and is connected to the drive unit 14 in a manner that can send instructions. The drive unit 14 is a drive circuit for operating the pump 15.

[0037] The pump 15 may have a structure that can suck the lubricating oil in the fuel tank 16 and eject a prescribed amount of lubricating oil. As the pump 15, a piston pump driven by pneumatic or hydraulic pressure, a hydraulic pump such as a gear pump, a diaphragm pump, etc. can be used.

[0038] According to the instruction from the control unit 13, the drive unit 14 operates the pump 15, and the lubricating oil is supplied to the bearing space via the nozzle 17. The end portion of the nozzle 17 extends into the interior of the bearing space. For example, when the inner ring rotates, the lubricating oil is ejected onto the outer peripheral surface of the inner ring 2 through the nozzle 17. More specifically, the lubricating oil is ejected near the side of the inner ring raceway surface 2a (opposite to the shoulder 2b). In this case, the ejected lubricating oil moves towards the inner ring raceway surface 2a due to centrifugal force, thereby eliminating the lack of oil on this raceway surface.

[0039] The amount of lubricating oil supplied each time by the lubricating oil supply mechanism 11 is preferably an extremely small amount that does not affect the torque variation of the bearing due to oil supply, for example, 0.001 mL to 0.1 mL. For example, the amount of oil supply and the oil supply timing can also be controlled according to the lubrication state of the rolling bearing. The lubrication state can also be detected, for example, by sensors provided inside or on the periphery of the rolling bearing.

[0040] The initial grease composition sealed in the rolling bearing device of the present invention in advance is a urea-based grease containing a thickener composed of a base oil and a urea compound.

[0041] The base oil used in the above grease composition can generally be a general base oil used in the field of greases. For example, paraffinic mineral oils, naphthenic mineral oils and other mineral oils, poly-α-olefin (PAO) oils, alkylbenzene oils, alkylnaphthalene oils, polyphenylene oils, synthetic naphthenic oils, polybutene oils and other synthetic hydrocarbon oils, ester oils, ether oils, silicone oils, fluorine oils, etc. can be cited. These oils can be used alone or in combination of two or more.

[0042] Among them, the base oil is preferably selected from the group consisting of synthetic hydrocarbon oils, ester oils, and a mixed oil of synthetic hydrocarbon oil and ester oil, and more preferably a mixed oil of synthetic hydrocarbon oil and ester oil.

[0043] The PAO oil as a synthetic hydrocarbon oil is a mixture of oligomers or polymers of α-olefins or isomerized α-olefins. Specific examples of α-olefins include 1-octene, 1-nonene, 1-decene, 1-dodecene, 1-tridecene, 1-tetradecene, 1-pentadecene, 1-hexadecene, 1-heptadecene, 1-octadecene, 1-nonadecene, 1-eicosene, 1-docosene, 1-tetracosene, etc., and usually their mixtures are used.

[0044] Ester oil is a compound having an ester group in the molecule and showing a liquid state at room temperature. For example, dibutyl sebacate, di-2-ethylhexyl sebacate, dioctyl adipate and other diester oils, aromatic ester oils such as trioctyl trimellitate, tridecyl trimellitate, pyrotetraoctyl tetrabenzoate, polyol ester oils such as trimethylolpropane octanoate, trimethylolpropane veratrol ester, pentaerythritol ester oil, carbonate oil, phosphate oil, polymer ester oil, etc. can be cited.

[0045] The kinematic viscosity of the above base oil at 40 °C (in the case of a mixed oil, it is the kinematic viscosity of the mixed oil, the same hereinafter) is less than 120 mm 2 / s. Thereby, the stirring resistance can be suppressed, for example, the rising amplitude of the temporary temperature rise during inertial operation can be suppressed. The kinematic viscosity is preferably 10 mm 2 / s to 50 mm 2 / s, and more preferably 10 mm 2 / s to 40 mm 2 / s. By making the above kinematic viscosity 10 mm 2 / s or more, it is easy to prevent evaporation during operation.

[0046] The thickener used in the above grease composition is a urea compound obtained by reacting a polyisocyanate component with a monoamine component. Examples of the polyisocyanate component include phenyl diisocyanate, toluene diisocyanate, diphenyl diisocyanate, diphenylmethane diisocyanate, octadecane diisocyanate, dodecane diisocyanate, hexane diisocyanate, etc. Among them, aromatic diisocyanates are more preferred. In addition, polyisocyanates obtained by reacting diamines (ethylenediamine, propylenediamine, etc.) with diisocyanates in an amount in excess of the diamine in terms of molar ratio can be used.

[0047] In addition, as the monoamine component, aliphatic monoamines, alicyclic monoamines, and aromatic monoamines can be used. Examples of the aliphatic monoamine include hexylamine, octylamine, dodecylamine, hexadecylamine, octadecylamine, oleylamine, etc. Examples of the alicyclic monoamine include cyclohexylamine, etc. Examples of the aromatic monoamine include aniline, p-toluidine, etc.

[0048] In the present invention, as the monoamine component, aliphatic monoamines are preferably used, and more preferably 50 mol% or more of aliphatic monoamines are used relative to the total monoamines. In this case, as the monoamine component, only aliphatic monoamines can be used, or aliphatic monoamines and alicyclic monoamines can be used in combination, or aliphatic monoamines and aromatic monoamines can be used in combination. As the monoamine component, it is generally considered that the use of aliphatic monoamines makes it easy to break up aggregates.

[0049] For example, a base grease is obtained by blending a bis-urea compound as a thickener in a base oil. The base grease with a bis-urea compound as a thickener is prepared by reacting a diisocyanate component with a monoamine component in a base oil. The thickener is, for example, 5% to 30% by mass, preferably 10% to 20% by mass, more preferably more than 10% and 14% or less, and further preferably more than 10% and 13% or less based on the total amount (100% by mass) of the base oil and the thickener.

[0050] In addition, in the above grease composition, known additives can be added as needed. Examples of the additives include antioxidants such as amines, phenols, and sulfur compounds; extreme pressure agents such as trimethyl phosphate and other phosphates, trimethyl phosphite and other phosphites, thiophosphate esters, thiophosphites, zinc dialkyl dithiophosphate (ZnDTP), molybdenum dialkyl dithiophosphate (MoDTP), zinc dithiocarbamate (ZnDTC), etc.; rust inhibitors such as Ca sulfonates and Ba sulfonates, etc.

[0051] The mixed consistency (JIS K 2220) of the above grease composition ranges from 230 to 300, preferably from 250 to 280. As shown in the examples described later, if the mixed consistency is less than 230, it is difficult to eliminate the aggregation of the thickener, and in addition, due to hardening, vibration is likely to be induced. On the other hand, if the mixed consistency exceeds 300, there is a possibility of reduced inertia.

[0052] Although the above grease composition shows relatively good lubrication durability, under further high-speed rotation conditions, there may be deterioration of the grease composition, oil shortage on the raceway surface, vibration, etc. In this regard, the rolling bearing device of the present invention supplies lubricating oil to the raceway surface by oil supply, thereby eliminating the oil shortage, and by eliminating the aggregation of the thickener (for example, refer to Figure 4 ), it is possible to suppress the development of deterioration of the grease composition and vibration.

[0053] As the lubricating oil supplied by the lubricating oil supply mechanism, various oils listed in the above base oils can be used. Among them, as the lubricating oil, it is preferably selected from the group consisting of synthetic hydrocarbon oils, ester oils, and mixed oils of synthetic hydrocarbon oils and ester oils. In addition, regarding the relationship with the base oil, for example, ester oil can be used in the lubricating oil, and synthetic hydrocarbon oil or a mixed oil of synthetic hydrocarbon oil and ester oil can be used in the base oil. In addition, as the lubricating oil, the same type of oil as the base oil can be used. For example, synthetic hydrocarbon oil can be used for both the lubricating oil and the base oil.

[0054] The kinematic viscosity of the lubricating oil at 40 °C is preferably 10 mm 2 / s to 100 mm 2 / s, more preferably 10 mm 2 / s to 50 mm 2 / s. In addition, the kinematic viscosity of the lubricating oil at 40 °C is preferably within ±30 mm 2 / s of the kinematic viscosity of the base oil at 40 °C, and can be within ±20 mm 2 / s, or within ±10 mm 2 / s, or can be the same as the kinematic viscosity of the base oil at 40 °C.

[0055] Considering the compatibility with the base oil, etc., the lubricating oil is preferably an oil type with high affinity to the base oil or an oil with a kinematic viscosity close to that of the base oil. Thereby, it is easy for the lubricating oil to reach the desired position (such as the raceway surface) after oil supply, and it is easy to appropriately exert the effect based on the oil supply.

[0056] As the operating time of the rolling bearing increases, the grease composition deteriorates and the oil separation rate of the grease composition rises. If the oil separation rate of the grease composition rises, it becomes difficult to form a sufficient oil film around the rolling elements. In the present invention, by supplying lubricating oil, the rising oil separation rate of the grease composition can be reduced. For example, by oil supply, the state with an oil separation rate of 50% or more (preferably 60% or more) can be reduced to an oil separation rate of 30% or less (preferably 25% or less). In addition, the oil separation rate is calculated by the following formula (1).

[0057] Oil separation rate (wt%) = {1 - (thickener concentration of new grease) / (thickener concentration of used grease)} × 100…(1)

[0058] In addition, in the lubricating oil, additives such as those listed in the grease composition may be added as needed.

[0059] In Figure 1 a centripetal thrust ball bearing is illustrated as an example of the rolling bearing, but the rolling bearing in the rolling bearing device of the present invention can also be used as a deep groove ball bearing, a cylindrical roller bearing, a tapered roller bearing, a self-aligning roller bearing, a needle roller bearing, a thrust cylindrical roller bearing, a thrust tapered roller bearing, a thrust needle roller bearing, a thrust self-aligning roller bearing, etc.

[0060] The rolling bearing device of the present invention is not limited to Figure 1 the structure. For example, as a part of the lubricating oil supply mechanism, a pump and a fuel tank can be arranged inside the rolling bearing, for example.

[0061] The rolling bearing device of the present invention has excellent lubrication durability even under high-speed rotation conditions and can be used for a long time. As the high-speed condition, specifically, the dn value is 70×10 4 or more, preferably 110×10 4 or more. The upper limit of the dn value is not particularly limited, for example, it is 200×10 4 , or 180×10 4 .

[0062] Thus, in the above rolling bearing device, since lubricating oil can be supplied to the rolling area of the rolling bearing, it can contribute to the long-term stabilization of the rolling characteristics and the improvement of the life.

[0063] Examples

[0064] As grease compositions pre-packed in rolling bearings, grease compositions having the compositions shown in Table 1 and Table 2 were respectively prepared. In Table 1 and Table 2, the contents of the base oil and the thickener are expressed as the contents (mass %) relative to the base grease (base oil + thickener). When the monoamine component of the thickener is a combination of an aliphatic monoamine and an alicyclic monoamine, or a combination of an aliphatic monoamine and an aromatic monoamine, the molar ratio of each amine is set to 1:1. In addition, for the lubricating oil supplied by the lubricating oil supply mechanism, the oil type and the additive column used are indicated by "○". In Table 1 and Table 2, PAO oil is used as the synthetic hydrocarbon oil. In addition, 1) to 8) described below Table 1 are the same in Table 2. In addition, the results of Example 3 are also described in Table 2 as a comparison object.

[0065] For the combinations of the grease compositions and the lubricating oil shown in Table 1 and Table 2, the following tests were carried out to evaluate each item.

[0066] 1. Amount of oil supply based on the thickener

[0067] 1-1. Adhesion work

[0068] For each grease composition, the adhesion between the non-oil-soluble components (thickener, solid additives, etc.) in the grease and the steel surface was determined as the adhesion work. In addition, the adhesion work is the energy required to separate two substances when they adhere at the interface. The greater the adhesion work, the stronger the adhesion. As a technique for quantitatively and simply evaluating the adhesion between the thickener and the steel, the adhesion work was measured using a "Surface Free Energy Contact Angle Meter (LSE-B100)" manufactured by Nick. First, the residue (organic solvent-insoluble part; grease solid component) obtained by Soxhlet extraction of the oil component (organic solvent-soluble part) from the grease composition was homogenized with a homogenizer and then diluted with petroleum spirit to prepare an immersion liquid. The specimen after immersing a steel test piece (made of SUJ2, Ra = 0.1 μm) and then evaporating the petroleum spirit was used as the test piece.

[0069] Two test liquids with known surface tensions (water, diiodomethane) were respectively dropped onto the prepared test piece. After measuring the contact angle θ, according to the two-component Kaelble-Uy theory (γ total =γ d +γ p ), the binary linear simultaneous equations of the Young-Dupre equation were solved to obtain the adhesion work W 12 (refer to Figure 2 's formula (2))). Figure 2 Shows the calculation outline of the adhesion work.

[0070] 1-2. Amount of oil supply

[0071] <Grease composition without ester oil in the base oil>

[0072] Using a life tester for working machinery, for example, with a dn value of 150×10 4 After completing the inertial operation based on the grease composition, an ester oil was applied as a specified amount of lubricating oil (tracer) at a specified position of the tester, and the movement amount of the ester oil was measured by FT-IR. The absorbance of the peak ([[]] Figure 3 (dotted line area in (b)) from the ester group was obtained from the infrared spectrum, and the movement amount was calculated based on the standard curve obtained in advance. The FT-IR of each sample in which a specified amount of ester oil was added to the grease composition was measured in advance, and a standard curve showing the relationship between the addition amount of the ester oil and the absorbance ratio as shown in Figure 3 (c) was obtained.

[0073] <Grease composition with ester oil in base oil>

[0074] Using a life tester for working machinery, for example, with a dn value of 150×10 4 After completing the inertial operation based on the grease composition, a lubricating oil added with a specified amount of ZnDTP (tracer) was applied at a specified position of the tester, and the movement amount of the Zn was measured by fluorescent X-ray. In this case as well, the movement amount was calculated using the standard curve obtained in advance.

[0075] Based on the comprehensive judgment of the results of the above adhesion work and the arrival amount of oil supply, the arrival amount of oil supply based on the thickener was evaluated. The good ones are rated as "A", and the bad ones are rated as "D", which are recorded in Tables 1 and 2 together.

[0076] 2. Ease of coagulation and dissociation of thickener

[0077] Using a life tester for working machinery, starting from, for example, a dn value of 150×10 4The grease composition after the test was collected from the bearings undergoing the running test. After transferring the collected grease composition to a container, an appropriate amount of lubricating oil (an amount with an oil separation rate of 0% when it can completely absorb the lubricating oil dropped from the sample specimen) was supplied and stirred. Then, the oil separation rate of the stirred grease was analyzed, and the reduction rate of the oil separation rate before the supply of the lubricating oil was obtained. In addition, the presence or absence of refinement of the aggregates of the thickener was confirmed by microscopic observation. Based on the above reduction rate and the results of microscopic observation, the ease of disassembly was determined. Regarding this evaluation, the case where the reduction rate of the oil separation rate is 40% or more and the aggregates are refined is rated as "A", the case where the reduction rate of the oil separation rate is 10% or more and less than 40% and the aggregates are refined is rated as "B", the case where the reduction rate of the oil separation rate is 10% or more and less than 40% and the aggregates have not changed is rated as "C", and the case where the reduction rate of the oil separation rate is less than 10% and the aggregates have not changed is rated as "D", which are all recorded in Table 1 and Table 2.

[0078] Herein, Figure 4 the microscopic observation is described. Figure 4 shows the microscopic image of the grease composition. Figure 4 (a) to (d) are images of the grease composition in each state observed with an optical microscope at a magnification of 200 times. Figure 4 (a) and (b) are the grease compositions of new products (unused) and are in a state where they have not been subjected to rolling or shearing forces. In these cases, regardless of the oil separation rate, no aggregates were confirmed. On the other hand, the grease composition was sealed in a rolling bearing and run at a high speed with a dn value of 150×10 4 After that, as Figure 4 (c) shows, aggregates of the thickener fibers were confirmed. Moreover, the state after supplying lubricating oil to the grease composition in this state and stirring is shown in Figure 4 (d). As Figure 4 (d) shows, a significant reduction in the oil separation rate (reduction rate of about 48%) and refinement of the aggregates were confirmed.

[0079] 3. Inertia

[0080] For example, with a dn value of 150×10 4Perform inertial operation based on the grease composition and operate until a stable temperature is reached. Regarding the evaluation of inertia, when the temporary temperature rise (temperature bulge) during inertial operation is compared with the stable temperature (temperature after inertia) at each rotational speed, if it is 30°C or less, it is designated as "A", if it exceeds 30°C and is 40°C or less, it is designated as "B", if it exceeds 40°C and is 50°C or less, it is designated as "C", and if it exceeds 50°C, it is designated as "D", and it is recorded in Table 1 and Table 2 together. In addition, in the inertial operation mentioned here, it does not include the "short-time inertia" of rotating for about 1 minute near the maximum rotational speed and repeating this 2 to 3 times for inertial operation.

[0081] [Table 11]

[0082]

[0083] 1) 14.3 mm 2 / s @ 40°C (PAO3.5)

[0084] 2) 30.7 mm 2 / s @ 40°C (PAO6)

[0085] 3) 65.1 mm 2 / s @ 40°C (PAO10)

[0086] 4) 97.1 mm 2 / s @ 40°C (Super Oil M100)

[0087] 5) 136 mm 2 / s @ 40°C (Super Oil M150)

[0088] 6) 32.9 mm 2 / s @ 40°C (kaolube262)

[0089] 7) 45.9 mm 2 / s @ 40°C (kaolube190)

[0090] 8) 90.7 mm 2 / s @ 40°C (ADEKA PURUBAR T90)

[0091] [Table 2]

[0092]

[0093] 9) Mineral oil + PAO oil + grease oil

[0094] As shown in Table 1 and Table 2, the kinematic viscosity of the base oil at 40°C is less than 120 mm 2Examples 1 to 11, which are combinations of a grease composition having a consistency of 230 to 300 and a lubricating oil, showed good results in all evaluations. In particular, regarding the ease of disentangling the aggregation of the thickener, more excellent results were obtained by keeping the consistency of the grease composition and the kinematic viscosity of the lubricating oil at 40 °C within an appropriate range (Examples 3, 8 to 11). Generally, since the lower the consistency, the larger the amount of thickener, a tendency of easier aggregation and more difficult disentanglement was observed (Comparative Example 3). In addition, although Comparative Example 4 showed excellent evaluation results for the ease of disentangling the aggregation of the thickener, a result of reduced inertia was obtained. It is generally considered that in Comparative Example 4, since the consistency was high and soft, it was difficult to change from the stirring state to the channel state, and it was also assumed that the grease reflowed onto the raceway surface, resulting in reduced inertia.

[0095] As Figure 4 (c) shows, if aggregates of the thickener are generated by high-speed rotation, vibration may increase as the rolling elements cross over the aggregates. In this regard, by supplying the lubricating oil as described above, the aggregates are refined by the lubricating oil and agitation based on rolling, resulting in a reduction in vibration.

[0096] As described above, by combining the supply of a specified urea-based grease and a lubricating oil, the aggregation of the thickener is disentangled and the lubricating oil is supplied without retention, enabling good lubrication durability under high-speed rotation conditions even in grease lubrication.

[0097] Industrial Applicability

[0098] The rolling bearing device of the present invention can ensure lubrication durability in grease lubrication even under high-speed rotation conditions and can suppress temperature rise during inertial operation, and thus can be particularly suitably used for rolling bearing devices used in high-speed rotation such as bearings for working machine spindles.

[0099] Explanation of Reference Numerals

[0100] 1 Angular Contact Ball Bearing (Rolling Bearing)

[0101] 2 Inner Ring

[0102] 3 Outer Ring

[0103] 4 Ball (Rolling Element)

[0104] 5 Cage

[0105] 6 Sealing Member

[0106] 7 Grease Composition

[0107] 11 Lubricating Oil Supply Mechanism

[0108] 12 Power Supply Unit

[0109] 13 Control unit

[0110] 14 Driving unit

[0111] 15 Pump

[0112] 16 Fuel tank

[0113] 17 Nozzle

[0114] 20 Rolling bearing device

Claims

1. A rolling bearing device, characterized in that, the rolling bearing device comprises: A rolling bearing having an inner ring, an outer ring, a plurality of rolling elements interposed between the inner ring and the outer ring, and a grease composition enclosed in a bearing space between the inner ring and the outer ring, the grease composition comprising a base oil having a kinematic viscosity at 40 °C of less than 120 mm 2 / s and a thickener composed of a urea compound, and having a mixed consistency of 230 to 300 as measured according to JIS K 2220; and a lubricating oil supply mechanism that supplies lubricating oil into the bearing space of the rolling bearing and supplies the lubricating oil to the raceway surface.

2. The rolling bearing device according to claim 1, characterized in that, the base oil and the lubricating oil are respectively selected from the group consisting of synthetic hydrocarbon oil, ester oil, and a mixed oil of synthetic hydrocarbon oil and ester oil.

3. The rolling bearing device according to claim 1, characterized in that, The kinematic viscosities of the base oil and the lubricating oil at 40 °C are both 10 mm 2 / s to 50 mm 2 / s.

4. The rolling bearing device according to claim 1, characterized in that, the mixed consistency of the grease composition measured according to JIS K 2220 is 250 to 280.

5. The rolling bearing device according to claim 1, characterized in that, the urea compound is a biurea compound obtained by reacting a diisocyanate component with a monoamine component, and the monoamine component contains an aliphatic monoamine.

6. The rolling bearing device according to claim 1, characterized in that, the base oil and the lubricating oil are respectively selected from the group consisting of synthetic hydrocarbon oil, ester oil, and a mixed oil of synthetic hydrocarbon oil and ester oil, The kinematic viscosities of the base oil and the lubricating oil at 40 °C are both 10 mm 2 / s to 50 mm 2 / s. comprising the thickener in an amount exceeding 10% by mass and not exceeding 14% by mass based on the total amount of the base oil and the thickener, the mixed consistency of the grease composition measured according to JIS K 2220 is 250 to 280.

7. The rolling bearing device according to claim 1, characterized in that, the lubricating oil supply mechanism ejects lubricating oil near the raceway surface of the inner ring.

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